CIRP ANNALS 2000
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STC A |
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Agile Assembly System by "Plug & Produce"
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T. Arai (1), Y. Aiyama, Y. Maeda, J. Ota
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STC A, 49/1/2000, P.1
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Keywords: Assembly, Holonic system, Agile system |
Abstract : Next generation assembly system is required to have high
flexibility and agility for changes in quantity of production.
For this purpose, supplement and reduction of manufacturing devices at
low setup cost should be required.
In this paper, we propose "plug & produce" concept. It is methodology to
introduce/install a new manufacturing device quickly and easily into a
manufacturing (sub-)system, and to remove it easily from the system.
It is made by analogy of "plug & play" concept in computer world.
Since our "plug & produce" works in real world, calibration among
devices is of importance.
We discuss procedures from the viewpoint of agility; set up interface
between devices and control system, calibration among devices and timing
coordination.
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Non-contact handling using high-intensity ultrasonics
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G. Reinhart (2), J. Hoeppner
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STC A, 49/1/2000, P.5
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Keywords: Non-Contact Handling, Acoustic Positioning, Ultrasonic Gripper |
Abstract : Increasing requirements placed on the handling of parts in
microsystem technology and semiconductor fabrication necessitate the
development of new innovative approaches for handling and transporting
miniaturised, fragile and surface-sensitive components. This is where
the technology of high-intensity ultrasonics offers itself as a suitable
approach for non-contact handling of parts and substrates.
While microparts can be positioned and manipulated within a standing
wave pattern, the application of the principle of near field levitation
makes it possible to design non-tactile grippers and transfer systems as
methods particularly suitable to ensure the material flow in microsystem
and semiconductor manufacturing and wafer processing.
The piezo-electric sound transducers used in this process, apart from
the non-contact application of forces, are designed to monitor these
forces by measuring the power input of the vibrators.
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New Feeding System for High Speed Assembly of Small Parts
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P.B. Petrovic (2), V.R. Milacic (1), G.M. Dzelatovic
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STC A, 49/1/2000, P.9
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Keywords: Automatic assembly, Part handling system, Axiomatic design |
Abstract : This paper presents the new general purpose automatic feeding
system, developed for high speed assembly of small parts. The new design is a result of the consequently applied Axiomatic Design Theory. The
feeding system is functionally uncoupled, leading to minimisation of
problems in system tuning, parts damage and noise emission. Moreover,
the new design gives the possibility for simple introduction of
additional functional modules such as: sensorized modules for
non-geometrical orientation of parts, or active orientation modules for
improving efficiency of the system. The proposed system is verified by
the prototype developed for feeding screws on pneumatic screwdriving
station.
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A method for sequencing the disassembly of products
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H. Kaebernick (2), B. O'Shea, S. Grewal (2)
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STC A, 49/1/2000, P.13
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Keywords: Disassembly, Sequencing, Task Allocation |
Abstract : In this paper a method for the creation of optimum disassembly
sequences is described. The method takes a graphical representation of
the product's structure and maps component disassembly cost and recovery
value, along with disassembly equipment requirements to the components
within the product. From this data the product is broken down into
sub-units of sequentially disassemblable component cells. All possible
parallel disassembly options are then displayed and the disassembly
sequence is optimised against the equipment available for the
disassembly process.
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STC C |
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Ultra-precision cutting for ZKN7 glass
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F.Z. Fang, L.J. Chen (2)
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STC C, 49/1/2000, P.17
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Keywords: Cutting, Brittle material, Surface finishing |
Abstract : ZKN7 is a silicate glass with a high softening point of 721
degrees Celsius and a Knoop Hardness of 530 kg/mm2. With this material,
there is an immense need to obtain nanometric surface finish owing to
the advantage of improved performance of the components. However, the
mere use of ultra-precision machining for this brittle material would
not yield mirror surface finish. Therefore, experiments were conducted
for the first time using diamond cutting for machining ZKN7 glass. Based
on the experimental work, a new strategy was proposed for obtaining
nanometric surface finish and the cutting mechanism was studied in
detail, where the surface roughness of Ra = 14.5 nm was achieved. The
sharpness of the cutting tools is a major factor to influence the
surface finish of workpieces. Thus, a new method for checking the
sharpness, namely tool edge radius was introduced in this study, which
is called Confocal Laser Scanning Microscopy (CLSM). Also, in this paper
an alternative approach was recommended for the fracture toughness
measurement of brittle materials.
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Suppression of tool wear in diamond turning of copper under reduced oxygen atmosphere
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S. Shimada (2), T. Inamura, M. Higuchi, H. Tanaka, N. Ikawa (1)
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STC C, 49/1/2000, P.21
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Keywords: Cutting, Diamond turning, Tool wear suppression |
Abstract : Tool wear mechanism in diamond turning of copper is
investigated by thermodynamics analysis and an erosion test which
simulates the wear process. The mechanism involves the removal of carbon
atoms on tool face due to oxidization accompanied with deoxidization of
copper oxide, which is formed with the atmospheric oxygen, by diamond.
Based on the results of the analysis and test, diamond turning of copper
under a reduced oxygen atmosphere is proposed. The cutting test results
in the decrease of tool wear to less than a few percent of that measured
under the normal one. These results suggest that the use of the reduced
oxygen atmosphere will be an effective way to supress excessive tool
wear in diamond turning of copper when large quantity production is
essential requirement.
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Predictive models for machining with multi-edge form tools based on a generalised cutting approach
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E.J.Armarego (1), A.B. Herath
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STC C, 49/1/2000, P.25
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Keywords: Cutting, Form Tool Operations, Predictive Force Modelling |
Abstract : In this paper predictive models for the force components, chip
flow and power in single and multi pass turning of helical vee grooves
as well as single pass turning at high and low feed to depth of cut
ratios with triangular profiled form tools have been developed. The
predictive models are based on generalised mechanics of cutting analyses
for machining with single and multi-edge form tools together with a
?generic? database of basic cutting quantities and edge force
coefficients found from ?classical? orthogonal cutting tests. The
mathematical models allow for all the tool and cut geometrical variables
as well as the cutting speed while the database allows for the
tool-workpiece material effects and tool coatings. The models have been
experimentally verified over a wide range of operation variables and
their predictive capabilities estimated in terms of the percentage
deviations between the measured and predicted forces. The developed
models are capable of predicting the tangential, feed and radial forces
within a deviation of 10 %37; ?on average?. This investigation has enabled
the ?Unified Mechanics of Cutting Approach? to performance prediction to
be extended to include machining with form tools.
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Improving productivity and part quality in milling of titanium based impellers by chatter suppresion and force control
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E. Budak / L. Kops (1)
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STC C, 49/1/2000, P.31
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Keywords: Milling, Chatter, Adaptive Force Control |
Abstract : Large axial depth of cuts used in the flank milling of gas
turbine impellers result in severe chatter vibrations and high cutting
forces. Variable pitch cutters can be used to suppress chatter in
milling of these extremely flexible components. A novel design method
for variable pitch cutters is presented. Cutting forces in 5-axis
milling cycles continuously vary due to changes in tool orientation and
depth of cut. Adaptive force control or milling force models can be used
to keep the forces at a constant level which reduces cycle times
significantly.
Benefits of both approaches are demonstrated through examples.
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The stability of low radial immersion
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M.A. Davies (2), J.R. Pratt, B.S. Dutterer, T.J. Burns
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STC C, 49/1/2000, P.37
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Keywords: High Speed Milling, Stability, Radial Depth |
Abstract : Traditional regenerative stability theory predicts a set of
spindle speeds with locally optimum stability at integer fractions of
the natural frequency of the most flexible mode of the system. The
assumptions of this theory become invalid for highly interrupted
machining, where the ratio of time spent cutting to not cutting (denoted
rho) is small. This paper proposes a new stability theory for
interrupted machining that predicts a doubling in the number of
optimally stable speeds as the value of rho becomes small. The
predictions are verified against experiment and numerical simulation.
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High speed ball nose end milling of Inconel 718
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E.G. Ng, D.W. Lee, A.R.C. Sharman, R.C. Dewes, D.K. Aspinwall / J. Vigneau (1)
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STC C, 49/1/2000, P.41
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Keywords: High speed machining, Inconel 718, cutting environment, tool coating |
Abstract : High speed machining (HSM) using ball nose end mills, is
attracting interest in the aerospace industry for the machining of
complex 3D aerofoil surfaces in nickel based superalloys and titanium
alloys. The paper initially reviews published data detailing the effect
of cutter/workpiece orientation (¡?BfN and ¡?Bf), tool
coatings/materials and cutting environments (spray mist, high pressure
flood, etc.) on tool performance. Experimental work is subsequently
detailed aimed at determining the effect of cutter orientation, tool
coating and cutting environment on tool life, tool wear mechanisms,
cutting forces, chip formation, cutting temperature and workpiece
surface roughness, when high speed ball nose end milling Inconel 718¢â.
A horizontal downwards cutter orientation with high pressure cutting
fluid (70 bar, 26 l/min) provided the best tool life with cut lengths of
~15 m which were twice as long as when employing a dry cutting
environment. Temperature measurements from the implanted thermocouple
technique, indicated that high pressure cutting fluid application
substantially reduced workpiece temperature from 320¢ªC when cutting
dry, to 175¢ªC.
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Identification of effective zones for high pressure coolant in milling
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M. Rahman (2), A.S. Kumar, M.R. Choudhury
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STC C, 49/1/2000, P.47
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Keywords: High pressure coolant, Tool wear, Cutting force |
Abstract : Effective zones of high pressure coolant have been identified
in milling performing a wide range of machining operations on ASSAB 718
mould steel using un-coated tungsten carbide inserts. The effects of
high pressure coolant are evaluated in terms of machining parameters by
comparing with those of conventional coolant and dry cut. Chipping and
catastrophic failure are the dominant factors of insert rejection for
dry cut and conventional coolant, whereas progressive flank wear is
observed for high pressure coolant within its effective zones at lower
depth of cut, lower feed rate and higher cutting speed. It is found that
the cutting force is reduced, surface finish is improved, chip width is
narrowed and cooling effect is better with the use of high pressure
coolant.
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Analysis of cutting fluid aerosol generation for environmentally responsible machining
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Z. Chen, A. Atmadi, D.A. Stephenson, S.Y. Liang / P.K. Venuvinod (1)
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STC C, 49/1/2000, P.53
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Keywords: Cutting Fluid, Environmental, Predictive Modeling |
Abstract : An analytical model is presented for the prediction of aerosol
generation from the use of metal cutting fluids. The model examines the
primary mechanisms of spin-off, splash, and diffusion to formulate the
airborne particulate concentration and size distribution in quantitative
terms of fluid properties, fluid application conditions, cutting process
parameters, as well as machining time. Experiments were performed with
the use of light scattering particle measurement to calibrate and verify
the analytical models. The predictive models developed herein can serve
as a basis for the control and minimization of the use of cutting fluids
in the interest of environmental consciousness.
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Comparison of methods for cutting fluid performance testing
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L. De Chiffre (1), W. Belluco
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STC C, 49/1/2000, P.57
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Keywords: Machining, Cutting fluid, Performance testing |
Abstract : A comparison is made of those methods for cutting fluid
performance evaluation that involve metal cutting operations under
controlled laboratory conditions. An analysis in terms of repeatability,
resolution and cost is carried out, based on results from comprehensive
experimental investigations in turning, drilling, milling, reaming, and
tapping. Different workpiece materials, such as carbon steels, stainless
steels, and aluminium alloys, as well as different kinds of cutting
fluids, including water based products, straight mineral oils, and
vegetable oil based formulations, are considered. The analysis is
carried out grouping the tests according to the main measurand: tool
life, cutting forces, and workpiece surface finish. The ratio
/, where  is the standard deviation of
measurements and  the range of variability of test results, was
introduced to express the relative resolution of a test, and a cost
model was developed. It was concluded from the analysis that tool life
tests are connected with limited repeatibility (=10-50%37;) and
resolution (/ ranging from 0.25-0.75), with costs
ranging from 1000? to 2000?. Tests based on cutting forces are connected
with a much better repeatibility and resolution, featuring values for
 in the range 0.5-6%37; and a / ratio of
approximately 0.2, with test costs of about 500. Surface finish tests
feature repeatabilities of approximately 50%37; and resolutions of 0.3-0.4,
with costs of approximately 1000?.
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An experimental investigation of air quality in wet and dry turning
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J.W. Sutherland, V.N. Kulur, N.C. King / B.F. Von Turkovich (1)
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STC C, 49/1/2000, P.61
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Keywords: Air Quality, Machining, Cutting Fluid |
Abstract : Environmental and industrial hygiene issues are receiving
increased attention by manufacturers. As a result a number of important
issues have arisen, one of which is air quality and its effect on worker
health. This paper presents the results of experiments focused on
characterizing the aerosol emissions associated with wet and dry
turning. Air quality is characterized by measuring the mass
concentration and particle size distribution of the dust and mist
created during a set of machining experiments. The relative importance
of vaporization/condensation and atomization as mist generating
mechanisms is also explored.
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Interpretation of PVD coated inserts wear phenomena in turning
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K.-D. Bouzakis (1), N. Michailidis, N. Vidakis, G. Erkens
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STC C, 49/1/2000, P.65
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Keywords: PVD coatings, HM inserts, Turning |
Abstract : PVD coatings attribute excellent cutting performance to
cemented carbide inserts. Based on the continuous chip formation,
coatings experience distinct failure mechanisms in turning. To clarify
the influencing parameters on coating wear resistance release, turning
experiments with a TiAlN derived coating, deposited on cemented carbide
inserts, have been carried out. The experimental results are explained
through analytical ones obtained by means of FEM calculations,
indicating a coating static decohesion at low cutting speeds, owing to
its overstressing. At higher cutting speeds, a coating adhesion
improvement was found out, whereas a further cutting speed increasing
reveals the dominant influence of tribomechanical abrasive phenomena and
adhesion release on the coating behavior. As the overall cutting length
increases, a progressive local coating decomposition occurs. Herewith
chip formation alterations are induced, such as a gradual increase of
the chip compression ratio and a consequent reduction of the tool
contact stresses.
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STC Dn |
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A methodology for collaborative design process and conflict analysis
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S.C.Y. Lu (2), J. Cai, W. Burkett, F. Udwadia
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STC Dn, 49/1/2000, P.69
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Keywords: Process, Engineering System, Co-operative Design |
Abstract : The process of collaborative engineering design is relatively
complex, and often results in various conflicts due to technical and
social factors. Therefore, to understand the relationships between
design process and design conflict is critical to improve the
collaborative design productivity. This paper provides a methodology for
analyzing collaborative design process and conflict based on a new
Socio-Technical design framework.
The methodology can identify the interdependencies among design tasks,
and manipulate the evolution of various design perspectives to
facilitate the management of design conflicts.
An initial computer implementation of this methodology is presented and
its features are discussed.
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Coordination between product and process deifinitions in a concurrent engineering environment
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S. Tichkiewitch (2), D. Brissaud
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STC Dn, 49/1/2000, P.75
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Keywords: Design, Product model, Process model |
Abstract : This paper deals with the necessary co-ordination among the
designing team members in a concurrent engineering environment. It
focuses on models and methods for co-ordination based on a co-operative
work.
The classical activity-based approach must be coupled with a
professional-based approach to have a co-ordination system close to
industrial practices. Then a first attempt to cluster the co-ordination
methods of the literature in a specific typology is discussed.
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Optimal combined usage of formulas, fuzzy-logic and neural networks for calculation in product development
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F.-L. Krause (1), A. Carl
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STC Dn, 49/1/2000, P.79
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Keywords: knowledge modeling; product development; neural network |
Abstract : This paper describes the optimal representation and
application of calculation-related knowledge in product development.
Classification into verified, uncertain and empirical knowledge supports
the choice of suitable representation methods: formulas, fuzzy logic and
neural networks. Potential use of neural networks will also be described
in further detail. Joint application of different knowledge types is
achieved by means of a hybrid simulation model combining the advantages
of different representation methods to provide the best possible supply
of knowledge. The modularization of knowledge components, which
significantly facilitates further use, and their representation
according to the quality of information are significant potential
applications of the hybrid simulation model.
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Design for bulk recycling: analysis of materials separation
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W.A. Knight (2), M. Sodhi
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STC Dn, 49/1/2000, P.83
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Keywords: Life Cycle Design, Product Analysis, Material Selection. |
Abstract : Increased interest in the life cycle design of products has
resulted in emphasis on the disassembly and recovery of materials at
product end-of-life. For many products the cost of disassembly will
outweigh the value of any materials recovered and such products will be
processed by bulk recycling involving shredding and mechanical material
separation. The efficiency of bulk recycling is influenced by a number
of factors including the selection of materials during product design.
This paper deals with the analysis of materials separation, which
determines the least cost or maximum profit level of materials
separation. This can be used for the evaluation of product designs for
efficient bulk recycling and the combination of disassembly and bulk
recycling.
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Waste-stream analysis of independent and original equipment automotive remanufacturers to support design for remanufacture
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M. Sherwood, L.H. Shu / R.G. Fenton (1)
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STC Dn, 49/1/2000, P.87
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Keywords: Design, Remanufacture, Waste stream |
Abstract : Waste streams of three automotive remanufacturers were
analyzed to determine factors that impede the reuse of parts. The
eventual goal of this work is to enable the design of products that
facilitate reuse. Remanufacturers disassemble and clean used products,
replace or repair failed parts, and reassemble products in a
production-batch process. Although design that facilitates any of these
steps benefits remanufacture, the essential goal of remanufacture is to
reuse parts. Parts not reused enter the waste stream. Worn parts that
could not be further refurbished were found to constitute the highest
contribution to the waste streams of the remanufacturers studied.
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The virtual maintenance system: a computer-based support tool for robust design, product monitoring, fault diagnosis and maintenance planning
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F.J.A.M. Van Houten (1), F. Kimura (1)
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STC Dn, 49/1/2000, P.91
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Keywords: Computer Aided Design, Maintenance, Simulation |
Abstract : Digital (geometric) product models can be used for
maintainability analysis and maintenance planning. It is not feasible to
build digital product models for maintenance purposes only, but if a
digital product model is available, it may be used to support many
maintenance-related engineering tasks. Examples are: Product life cycle
simulation (the influence of product use on product performance),
deterioration analysis (the influence of wear on product function),
Failure Mode Effect Analysis (FMEA), product model-based monitoring (to
relate sensor signals to failure modes), failure diagnosis,
disassemblability analysis (for repair and replacement), maintenance
ergonomic analysis (to ease the work of maintenance personnel), etc.
At the University of Tokyo, a Virtual Maintenance System has been
developed to support the activities mentioned above. The system makes it
possible to relate predicted product behaviour and specific signals,
which can be detected by sensors and can be used to avoid catastrophic
failure. This creates better possibilities for condition-based
maintenance and Design for Maintainability. Future CAD systems should
support product life cycle issues right from the start of the design
process.
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Axiomatic design of software systems
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N.P. Suh (1), S.H. Do
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STC Dn, 49/1/2000, P.95
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Keywords: software, axiomatic, design |
Abstract : Software is playing an increasingly important role in
manufacturing. Many manufacturing firms have problems with software
development. Software engineering is still labor- intensive and prone to
errors. Industrial firms are under pressure to shorten the lead-time
required in introducing new software, increase the reliability of their
software, and increase their market share. Software must be designed
correctly from the beginning to end. With this end in mind, axiomatic
design theory has been applied to software design. This paper presents
how the combination of axiomatic design has been combined with the
object-oriented programming method to create a large software system.
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Design of a microactuator array against the coupled nature of micro-electromechanical systems (MEMS) processes
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S.G. Kim (2), M.K.Koo
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STC Dn, 49/1/2000, P.101
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Keywords: micro-actuator, micro-machining, axiomatic design |
Abstract : Piezoelectric micromirror array is developed based on
microelectromechanical systems (MEMS) technology. The inherent coupled
nature of the thin-film processes generates many problems unless the
design of the microactuator is properly uncoupled or decoupled among the
functional domain, the physical domain and the process domain. The
design of the first generation microactuator array was highly coupled
between the functional domain and the physical domain, and could not be
implemented successfully over 24 months of fabrication effort. Once the
design has been uncoupled, successful arrays could be fabricated within
6 months and could be upgraded easily. The brightest projection display
system has been developed with the microactuator arrays.
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Product and assembly design for a fibre reinforced plastic track wheel
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S. Lange, H. Schmidt, G. Seliger (2)
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STC Dn, 49/1/2000, P.105
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Keywords: FRP wheel, product design, assembly process |
Abstract : The design of silent and lightweight components with minimised
life cycle costs are the main requirements for modern railroad systems.
The track wheel as the interface between railroad and vehicle offers a
high potential for optimisation. The application of fibre reinforced
plastic (frp) in the wheel body simultaneously minimises sound emissions
and reduces wear effects by lowering unsprung wheel masses. This paper
presents a new modular track wheel design with frp discs in combination
with steel flanges. Several design and assembly alternatives have been
analysed and an optimised solution based on numerical simulation and new
fibre preform technologies has been selected. With regard to the high
security requirements on track wheels, design specific quality assurance
test methods and maintenance plans and operations have been developed.
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Heterogeneous solid modeling for layered manufacturing
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D. Dutta, M. Shpitalni (1)
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STC Dn, 49/1/2000, P.109
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Keywords: images/cirpfichiers/annals/ CAD/CAM, Geometric Modeling, Rapid Prototyping |
Abstract : We consider layered manufacturing as a fabrication technique
for metallic, functional parts. While commercial machines still do not
support metals, several research systems are already in existence in
universities and research laboratories. Such systems can create
multi-material parts and can vary material composition within the layer.
A key enabling technology for the automation of such layered
manufacturing systems is heterogeneous solid modeling. Current CAD
systems do not provide the capability to deal explicitly with material
heterogeneity. We provide an overview of this new field, propose a
method for modeling and representing material in addition to geometry
and topology, and discuss some related research.
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Visibility theory applied to automatic control of 3D complex parts using plane laser sensors
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A. Bernard (2), M. Veron (1)
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STC Dn, 49/1/2000, P.113
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Keywords: Reverse engineering, Scanning, Inspection, Optimisation |
Abstract : Rapid product development is today widely developped in design
and industrialisation stages of the development of a new product. Rapid
tooling and manufacturing technologies allow to produce rapidly very
complicated parts, from a numerical model. The model is to be able to
obtain a rapid validation of the technological processes in order to
verify the conformity of the part compared to the numerical reference
model. So, the goal is to control efficiently parts that have most often
a very complex geometry. Based on our experience on laser [Veron, 99],
our paper proposes a solution in order to improve the efficiency of the
geometric and dimensionnal control process [Sidot, 99].
The proposed solution is an application and adaptation of the visibility
theory to the automatic determination of the scanning strategies for the
digitization of 3D complex parts, using a plane laser sensor.
This has been applied in different industrial fields lidke foundry,
plastic injection, etc...
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STC E |
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Development of multi-spark EDM
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M. Kunieda (2), H. Mutoh
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STC E, 49/1/2000, P.119
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Keywords: Die-sinking EDM, Multi-spark, Discharge point |
Abstract : This paper describes the Multi-spark EDM method which was
newly developed to obtain higher removal rates and lower energy
consumption compared with conventional EDM. The basic circuit of
Multi-spark EDM comprises a pulse generator, a first tool electrode, the
workpiece, and a second tool electrode that are connected serially in
the order as listed here. Accordingly, for each generator pulse, one
discharge occurs in the gap between the first tool electrode and the
workpiece, and another discharge occurs at the same time in the gap
between the other tool electrode and the workpiece. To balance the
removal rates in both gaps, the polarity of the pulse generator is
changed adaptively to equalize the gap voltages measured at both gaps.
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A new process of additive and removal machining by EDM with a thin electrocode
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N. Mohri (2), H. Takezawa, K. Furutani, Y. Ito, T. Sata (1)
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STC E, 49/1/2000, P.123
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Keywords: Electrical discharge machining, Electrode, Surface |
Abstract : Removal machining or additive machining can be performed in
electrical discharge machining (EDM), under proper machining conditions.
In this paper, rapid accretion of a thin electrode material and rapid
manufacturing of a thin electrode are proposed. The material of a thin
electrode can be accreted onto a work piece in an instant through an
explosion process. A needle of 35mm in diameter and 300mm length can be
made under a single discharge pulse instantaneously from a tungsten wire
of 125mm in diameter. Micro drilling and rapid implantation of electrode
material onto a work piece can be performed. The machining mechanisms
are discussed taking into consideration the thermal properties of the
thin electrode and the machining conditions.
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3D Micro-EDM using CAD/CAM
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K.P. Rajurkar (2), Z.Y. Yu
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STC E, 49/1/2000, P.127
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Keywords: EDM, Micro-machining, Wear |
Abstract : It is necessary to integrate CAD/CAM systems with micro-EDM to
generate tool paths when simple shaped tools are used to machine
three-dimensional (3D) micro parts. Currently available CAD/CAM systems
cannot be directly used because of the continuous tool electrode wear
during machining. This paper proposes an approach to integrate CAD/CAM
systems with micro-EDM while accounting for tool wear using a recently
developed uniform wear method. This approach is verified by successfully
generating very complex 3D micro cavities. Additionally, the feasibility
of the approach is illustrated by generating complex macro cavities
using conventional EDM with single simple shaped electrodes.
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A quality evaluation method for laser welding of Al alloys through neural networks
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L.M. Galantucci (2), L. Tricarico, R. Spina
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STC E, 49/1/2000, P.131
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Keywords: Welding, Laser, Quality |
Abstract : The authors propose an integrated methodology to evaluate the
quality of Aluminium alloy butt joints welded by laser. The method,
starting from the observation of the results of an experimental
investigation, focuses on the definition of a omni-comprehensive quality
index for welded joints. This index is obtained using the limits of
imperfections for the quality level defined by the ISO 13919 standard. A
neural network system has been developed to classify and evaluate the
different welds.
The experiments were performed on Al 6110 T61 alloy, welded using a 6 kW
CO2 laser beam on plane sheets with a continuous butt joint.
Computerised image processing has been used to recognise and to quantify
the imperfections in the weld cross section. The defects have been
divided into groups, as required by the EN 26520 standard.
Due to the huge number of measurements required to imperfections, the
artificial neural network very greatly simplifies the relationship
between the quality index and the main process parameters.
The neural network was trained with a set of data containing very
different welding parameter choices.
Application of the system aids process parameter selection that has
proved to be in good agreement with quality levels measured on
experimental welds made under the same conditions.
Inverse calculation of power density for laser surface treatment
/G.R.B.E. Römer, J. Meijer (2)/
STC E, 49/1/2000, p. 135
Key words: Laser, Surface treatment, Heat transfer
Laser beam surface treatment requires a well defined
temperature profile. In this paper an analytic method is presented to
solve the inverse problem of heat conduction in solids, based on the
2-dimensional Fourier transform. As a result, the required power density
profile of the laser beam can be calculated for any desired temperature
field. Methods to reduce the effects of errors introduced by
calculations on a finite grid and physically impossible temperature
gradients are addressed. A software utility, which interactively
calculates the power density distribution for a user defined temperature
field, will be presented. Results are given for the laser beam hardening
process.
|
|
A new method for three dimensional excimer laser micromachining, Hole Area Modulation (HAM)
|
|
T. Masuzawa (1), J. Olde-Benneker, J.J.C. Eindhoven
|
|
STC E, 49/1/2000, P.139
|
|
Keywords: LBM, excimer laser, micromachining |
Abstract : A new excimer laser system configuration for three dimensional
(3D) micromachining, called Hole Area Modulation (HAM) method, is
proposed and the feasibility of the system is experimentally confirmed.
In this method, information on the depth of machining is converted to
the sizes of small holes in the mask. The machining is carried out with
a simple 2D movement of the workpiece. Since the total area of the
targeted cavity is machined simultaneously, a 2.5-µm-deep, 800µm x
1600µm 3D cavity was machined in about 5s. This method can be applied
for machining various kinds of microcavities in various materials. Owing
to the short machining time, the fabrication of a mold with repeated
shapes, for example a mold for a microlens array, will be a good
application in the future.
|
|
Synthesis and analysis of a digital droplet-size control system
|
|
J.H. Chun (2), J.C. Rocha, J.H. Oh
|
|
STC E, 49/1/2000, P.143
|
|
Keywords: Metal Powder, Digital Feedback Control System, On-line Monitoring |
Abstract : This paper presents a digital control system for the
production of uniformly sized molten metal droplets using laminar jet
break-up caused by Rayleigh¡¯s instability. First, the control plant is
represented as an algebraic affine nonlinear system with disturbances.
To obtain an on-line droplet diameter measurement, an imaging system was
employed and an image processing algorithm was developed. Then, a
digital integral controller was synthesized, and explicit stability
conditions were derived and incorporated in the design of the
controller. The proposed control system is shown to provide uniformly
sized droplets of molten metals with the melting temperatures of up to
1200 degrees C., with less than 3%37; variation over the diameter range of
100-800 microns, despite the existence of disturbances.
|
|
An experimental and analytical study of ice part fabrication with rapid freeze prototyping
|
|
M.C. Leu (2), W. Zhang, G. Sui
|
|
STC E, 49/1/2000, P.147
|
|
Keywords: Rapid Prototyping, Freezing, Ice Part |
Abstract : This paper will present the results of study on a novel,
environmentally conscious solid freeform fabrication process called
Rapid Freeze Prototyping. This process builds a three-dimensional ice
part by depositing and rapidly freezing water according to its CAD model
in a layer-by-layer manner. It provides a means to build a solid part
with the potential of better performance than other rapid prototyping
processes, including use of cheap and clean material, potential to build
accurate ice parts with excellent surface finish, and ease of building
color and transparent parts. An experimental system with a
low-temperature building environment, a three-axis positioning
mechanism, a water feeding and extruding subsystem, and control hardware
and software has been built. Experiments conducted on this system
demonstrate the feasibility of making three-dimensional ice parts. A
heat transfer analysis helps understand the freezing process and
provides useful information to the selection of building parameters.
|
|
Precision ECM by process characteristic modelling
|
|
A.K.M. De Silva, H.S.J. Altena, J.A. McGeough (1)
|
|
STC E, 49/1/2000, P.151
|
|
Keywords: ECM, precision, modelling |
Abstract : Electrochemical machining (ECM), which is not normally
considered as a precision process, is used to achieve accuracy better
than 5 m and surface finish 0.03 m Ra by using pulsed
power of relatively short durations (1 - 10 ms) and narrow
inter-electrode gaps (10 - 50 m). The narrow gaps, however, make
the control and prediction of the process much more complex than normal
ECM. An empirical model is developed based on the characteristic
relationships of ECM to predict and optimise the process parameters such
as dissolution efficiency, current density, electrolyte concentration
and pulse duration, in narrow gaps. This model is then used to
facilitate new applications of high precision ECM without recourse to
the lengthy trial-and-error approach, by predicting selective
dissolution of the workpiece and tool design.
|
|
Development of electroformed diamond tool with fine grains coated by metal oxide film
|
|
T. Semba, H. Sato (1)
|
|
STC E, 49/1/2000, P.157
|
|
Keywords: High speed electroforming, Fine grains, Modified grain surface |
Abstract : A high-speed electroforming technique that can produce an
electroformed tool efficiently is developed to overcome a disadvantage
of the conventional sediment codeposition technique that an extremely
long time is required for the production of thick composite coatings.
Aggregated diamond grain particles sedimented on a tool surface are
agitated at a low speed with a rubber blade to increase the electric
conductivity and to disperse the grain particles uniformly on the tool
body. The time required to produce a thick nickel-diamond coating of 1
mm thickness is successfully reduced to 2.5 hours from the minimum of 81
hours required by the conventional sediment codeposition technique.
|
STC F |
|
Fundamental study of dry metal forming with coated tools
|
|
K. Osakada (1), R. Matsumoto
|
|
STC F, 49/1/2000, P.161
|
|
Keywords: Forming, Friction, Tool |
Abstract : To realize dry metal forming processes without lubrication,
the frictional behavior of some working metals sliding over tool
surfaces without lubricant is studied. To measure the coefficient of
friction in the high friction range by the ring compression test, an
optimum shape of ring specimen is proposed. The work-metals are Al, Cu
and carbon steel, and the cemented carbide tools are coated with TiC,
TiN, TiCN, TiAlN and DLC (diamond like carbon). It is found that DLC is
effective to reduce the friction with aluminum under dry condition. The
oxide layer formed on the steel surface raises the friction to a great
extent. The coefficient of friction is sensitively affected by the
roughness of the tool surface irrespective of the coated material.
|
|
Lubricant behavior trapped within pockets on workpiece surface in lubricated upsetting by means of direct fluorescence observation technique
|
|
A. Azushima (2), T. Tanaka
|
|
STC F, 49/1/2000, P.165
|
|
Keywords: Upsetting, Tribology, Direct measurement |
Abstract : It is important to understand the trapping behavior of liquid
lubricant within pockets on the workpiece surface at the tool-workpiece
interface during metal forming in order to characterize and qualify the
surface structure of workpiece.
Therefore, it is tried to measure the lubricant behavior trapped within
pockets in lubricated upsetting. In order to measure the lubricant
behavior, a direct fluorescence observation technique which consists of
a direct observation method and a conventional fluorescence method. The
lubricant behavior and the pocket geometry are measured by means of the
technique. The volume of the oil pocket decreases with increasing
reduction in height. From these results, it is confirmed that the
lubricant trapped within the pockets is permeated into the real contact
area. The volume change of the oil pocket depends on the position on the
end surface of workpiece and the geometry of cylindrical specimen.
|
|
Prediction of dimensional difference of product from tool in cold backward extrusion
|
|
T. Ishikawa, N. Yukawa, Y. Yoshida, H. Kim, Y. Tozawa (1)
|
|
STC F, 49/1/2000, P.169
|
|
Keywords: Cold forging, Dimensional accuracy, FEM |
Abstract : The effects of forming stresses and generated heat on the
dimensional change of punch, die and work piece during forging are
discussed analytically. The change in outer and inner diameter of
backward extruded cup is investigated numerically using
thermo-elastic-plastic FEM code according to the actual forging
sequence, namely extruding, unloading of punch force, and ejection and
air cooling of extruded cup. The calculated results of outer and inner
diameters of product are in good agreement with the experimental
results. The simulation can be used to determine the initial tool
dimensions for precision parts in the tool design process of cold forging.
|
|
A development of ceramic inserts for forging tools
|
|
H.H. Kwon, A.N. Bramley (1)
|
|
STC F, 49/1/2000, P.173
|
|
Keywords: Forging, Die, Ceramic |
Abstract : The use of ceramic inserts in steel forging tools offers
significant technical and economic advantages over other materials of
manufacture.
These potential benefits can however only be realised by optimal design
of the tools so that the ceramic inserts are not subjected to stresses
that lead to their premature failure. In this paper the data on the
loading of the tools is determined from a commercial forging simulation
package as the contact stress distribution on the die-workpiece
interface and as temperature distributions in the die. This data can be
processed as load input data for a finite-element die-stress analysis.
Process simulation and stress analysis are thus combined during the
design, and a data exchange program has been developed that enables
optimal design of the dies taking into account the elastic deflections
generated in shrink fitting the die inserts and that caused by the
stresses generated in the forging process. The stress analysis of the
dies is used to determine the stress conditions on the ceramic insert by
considering contact and interference effects under both mechanical and
thermal loads.
Simulation results have been validated as a result of experimental
investigations. Laboratory tests on ceramic insert dies have verified
the superior performance of the Zirconia and Silicon Nitride ceramic
insert in order to prolong maintenance life.
|
|
Development of integrated and intelligent design and analysis system for forging processes
|
|
D.Y. Yang (1), Y.T. Im, Y.C. Yoo, J.J. Park, J.H. Kim, M.S. Chun, C.H. Lee, Y.K. Lee, C.H. Park, J.H
|
|
STC F, 49/1/2000, P.177
|
|
Keywords: metal forming, finite element method, expert system |
Abstract : An intelligent system for supporting the whole design
procedure of metal forming processes has been developed by integrating
the expert systems, the FEA programs and the CAD interface modules. The
system is developed to reduce the time, effort and cost in order to
establish the successful metal forming processes of planned products. In
order to promote practical applications by engineers in medium-size
enterprises who are not theoretically expertized in the FEA and the
other related knowledge, various databases and intelligent user
interface modules have been developed in PC environment.
|
|
An investigation of the pinch and roll process of compressor airfoil manufacture
|
|
J.S. Gunasekera (2), R.A. Belinski
|
|
STC F, 49/1/2000, P.181
|
|
Keywords: blade forming, fem, data acquisition |
Abstract : This paper is concerned with a scientific study of the pinch
and roll process that is currently used to produce compressor blades for
jet engines. The investigation jointly uses experimental data and
validated 3-dimensional finite element analysis to improve the process.
A unique data acquisition system was developed to gather process data as
well as to improve the press set up for production runs. The data
acquisition system provides process information such as die separation
forces and displacements, and rotational die mismatch. Designed
experiments were carried out on both the actual process and the
simulations. The process experiments identified the intricacies of this
complex process. The simulation experiments clarified the significant
factors for proper simulations of the process. All of these methods of
analysis are combined to improve the competitiveness of the pinch and
roll process by improving the quality of the product while reducing the
number of roll passes required, thus reducing the overall cost.
|
|
Manufacturing of superconducting silver/ceramic composites
|
|
B. Seifi, J.I. Bech, M. Eriksen, p. Skov-Hansen, W.G. Wang, N. Bay (1)
|
|
STC F, 49/1/2000, P.185
|
|
Keywords: Manufacturing of superconductors, Drawing and rolling, Metal/ceramic composites |
Abstract : Manufacturing of superconducting metal/ceramic composites is a
rather new discipline within materials forming processes. High
Temperature SuperConductors, HTSC, are manufactured by the
Oxid-Powder-In-Tube process, OPIT. A ceramic powder containing lead,
calcium, bismuth, strontium, and copper oxides is inserted into a silver
tube and reduced by multistep drawing. These singlefilaments are packed
in a new silver tube thus forming a multifilament containing e.g. 37
singlefilaments, which is subsequently reduced by drawing and rolling to
tapes approximately 0.2 mm thick by 3 mm wide. After the mechanical
deformation the tapes are heattreated at approximately 835C
whereby the powder-cores by phase diffusion and grain growth are
converted into superconducting, ceramic fibres. The geometry, density
and texture of the powder cores before heattreatment is essential for
the quality and current leading properties of the final superconducting
fibres. The present work describes studies on alternative packing
geometries and on process parameters in the flat rolling operations in
order to obtain homogenous filaments with advantageous geometry and good
texture while avoiding potential defects such as cracks, shear band
formation and sausaging.
|
|
Developments in powder co-injection moulding
|
|
D.J. Stephenson / P.A. Mckeown (1)
|
|
STC F, 49/1/2000, P.191
|
|
Keywords: Powder Injection Moulding, Coating, Modelling |
Abstract : Powder co-injection moulding (PCIM), is a novel technique for
the surface engineering of PIM components. The process uses two moulding
feedstocks which are injected into a mould sequentially, so that one
feedstock forms the surface layer of the component and the other forms
the core. Work to date has shown that the injection moulding time and
the viscosity ratio of the two feedstock materials are critical in
determining the surface layer profile. This has been confirmed through
finite element modelling predictions of the skin layer thickness
distribution which correlate well with experimental observations.
|
|
A new Constitutive model for hot forging of steels taking into account the thermal and mechanical history
|
|
P.F. Bariani (1), S. Bruschi, T. Dal Negro
|
|
STC F, 49/1/2000, P.195
|
|
Keywords: Hot forging, Flow stress, Thermo-mechanical cycle |
Abstract : The paper presents a new constitutive model which accurately describes
the rheological behaviour of steels in hot bulk metal forming operations
both in single- and multi-step deformation conditions. In the proposed
formulation the effects on the flow curve of all the significant
phenomena accompanying the deformation process are accommodated and the
previous thermo-mechanical history is represented through the average
austenitic grain size measured immediately before the deformation.
The number of coefficients to be evaluated is reasonably restricted and
the testing required to this aim not too complex.
|
|
Strain history curves and simulative material testing
|
|
M.S. Nielsen, T. Wanheim (1), M. Lindegren
|
|
STC F, 49/1/2000, P.199
|
|
Keywords: metal forming, non-linear strain, graphical method |
Abstract : A way of describing the deformation in a process where large
plastic deformation occurs is presented. For a point in the volume, the
total strain tensor history is viewed as a curve in the 6-dimensional
shear strain, normal strain space henceforth called a strain history
curve (SHC). This paper focuses on the SHC concept and the uniqueness of
the SHC representation.
The SHC may be used to give a useful representation of the total course
of the deformation with respect to directions and magnitudes of the
strain, and hence the development of the plastic properties, but may
also be used for developing variables describing plasticity. A direct
use of the SHC is to measure the yield surface at different points at a
SHC, thus establishing data describing the importance of strain
rotations or even strain reversals within a process. Two subcases for
displaying SHC will be mentioned: The plane strain case and the
axisymmetrical case. The origin of the SHC in this paper is to make a
method of classifying processes after strain path and hence the need for
using advanced plasticity models.
Use of the SHC is presented in the following process examples:
1) Extrusion process (numerical)
2) Simple shear followed by upsetting (experimental)
3) Plane strain upsetting with subsequent orthogonal reversals of
straining direction (experimental)
4) Upsetting with orthogonal reversals of straining direction
(experimental)
|
|
An improved relationship between vickers hardness and yield stress for cold formed materials and its experimental verification
|
|
E. Tekkaya / K. Lange (1)
|
|
STC F, 49/1/2000, P.205
|
|
Keywords: Cold forming, Vickers Hardness, Yield stress |
Abstract : Cold formed products are increasingly serving as high duty
machine parts. Designers and users need to know their properties as
accurate as possible. One such product property is the new yield stress,
which can be approximated by the final flow stress of workpiece material
during forming. Vickers hardness measurements provide an easy and
inexpensive method for evaluating the new local yield stress in cold
formed workpieces. In this study, an improved relationship for the
conversion of Vickers hardness values to yield stress is proposed. The
agreement between theoretical and experimental results is better than 4%37; error.
|
|
Overall thermal analysis of hot plate / sheet rolling
|
|
M. Kiuchi (1), J. Yanagimoto, E. Wakamatsu
|
|
STC F, 49/1/2000, P.209
|
|
Keywords: Sheet, Hot Rolling, Numerical, Thermal, FEM |
Abstract : A new scheme of three-dimensional thermal analysis of workpiece
temperature and roll temperature in hot plate/sheet rolling is proposed.
Mathematical models and numerical analysis are based on a modified
finite element method.
The results are as follows. (1) The temperature change at each portion
of workpiece during hot rolling was calculated in detail. (2) The
effects of rolling parameters on the workpiece temperature and roll
temperature were consistently clarified. (3) The calculated results were
used for process design and process control. (4)They are essential for
innovation of hot plate/sheet rolling processes as well as quality
control of rolled products.
|
|
Processing effects in plasma forming of sheet metal
|
|
T. Male, C. Pan, Y. W. Chen, p. J. Li, Y. M. Zhang / T. Altan (1)
|
|
STC F, 49/1/2000, P.213
|
|
Keywords: Hot forming, Sheet metal, Plasma |
Abstract : A non-transferred arc plasma torch has been used as a
controllable heat source to produce internal stress in sheet metals,
causing plastic deformation without the necessity of hard tooling. This
method has the potential to reduce development cost and lead time for
forming sheet metal prototype parts. Experimental work using a robotic
system has been performed on 0.8mm thick sheets of Type 304 stainless
steel and of low carbon (mild) steel. The effects of various process
parameters on the obtained shape changes and on the resulting material
microstructures has been studied. Data is presented for the development
of simple linear bends in the two materials as a function of the process
parameters which directly affect the rate of heat input.
|
|
Hydromechanical deep drawing with uniform pressure on the flange
|
|
J. Danckert (1), K.B. Nielsen
|
|
STC F, 49/1/2000, P.217
|
|
Keywords: Sheet metal, Deep drawing, FEM |
Abstract : Conventional hydromechanical deep drawing is difficult to
simulate due to difficulties regarding the determination of the pressure
distribution on the flange when leak flow occurs between the draw die
and the flange. To avoid this problem the hydromechanical deep drawing
process has been modified in such a way that the pressure on the flange
is uniform throughout the deep drawing. The uniform pressure on the
flange makes it easy to simulate the modified hydromechanical deep
drawing process.
The modified hydromechanical deep drawing process has been investigated
experimentally and the experiments show that the new concept works in
practice; cylindrical cups made from aluminium have been drawn
succesfully with a drawing ratio as high as 2.75.
The paper presents the modified hydromechanical deep drawing process and
experimental results are compared to results obtained using FEM.
|
|
An intelligent controller for improving the quality of deep drawn components
|
|
S. Hinduja (2), J. Atkinson, D.K.Y. Lau, A.W. Labib, p. Agirrezabal
|
|
STC F, 49/1/2000, P.221
|
|
Keywords: Deep Drawing, Control, Quality |
Abstract : A prototype system, which detects wrinkling and tearing in
sheet metal parts, has been developed. A spatial variation of the
blankholding force (BHF) is achieved by hydraulic adjustment of the
force in the BHF pins which are subdivided into groups.
Neural networks predict the presence of wrinkles. Tears are predicted
from the punch force signals using feature extraction techniques. A
fuzzy logic controller (FLC) recommends changes to the BHF and
lubrication to improve the quality of the next part. The results
obtained when drawing the back panel of a washing machine are discussed.
|
STC G |
|
Stability diagram for chatter free centerless grinding and its application in machine development
|
|
F. Hashimoto (2), S.S. Zhou, G.D. Lahoti (1), M. Miyashita
|
|
STC G, 49/1/2000, P.225
|
|
Keywords: Centerless Grinding, Chatter Vibration, Stability Diagram |
Abstract : Suppression of work regenerative chatter vibration is one of
the most important issues for improving centerless grinding performance.
Current practice to avoid such chatter vibration largely relies on a
trial-and-error method. Based on the stability diagram, this paper
introduces a systematic approach to achieving chatter free centerless
grinding. In the paper, the significance of the ratio of work rotational
speed to center-height angle is first discussed, the chatter free zones
are then identified from the diagram. The conditions for chatter free
centerless grinding are further determined by considering the effect of
lobing stability and contact filtering. Practical significance of the
approach is demonstrated with grinding test results. Further, the
performance of a high precision centerless grinding machine developed
with enhanced dynamic stability is presented.
|
|
Development of a sensor-integrated "intelligent" grinding wheel for in-process monitoring
|
|
B. Varghese, S. Pathare, R. Gao, C. Guo, S. Malkin (1)
|
|
STC G, 49/1/2000, P.231
|
|
Keywords: Grinding, Wheel, Sensor |
Abstract : A sensor integrated "intelligent" diamond grinding wheel was
developed for in-process monitoring of the wheel preparation and
grinding processes for machining of ceramics without the need for any
instrumentation of the machine tool. The "intelligent" grinding wheel
consists of an aluminum core integrated with piezo-ceramic sensors and
having diamond abrasive segments bonded on to the periphery. Multiple
sensors embedded near the wheel periphery are used to measure the
instantaneous normal force and its variation during each wheel
revolution, and additional sensors on the wheel face monitor the
acoustic emission. A DSP-based telemetric data acquisition system module
attached to the wheel face is used to acquire, process, and transmit
data from the rotating wheel to a remote receiver. Experimental results
are presented which demonstrate the performance of the intelligent wheel.
|
|
Grinding monitoring system based on power and acoustic emission sensors
|
|
B. Karpuschewski, M. Wehmeier, I. Inasaki (1)
|
|
STC G, 49/1/2000, P.235
|
|
Keywords: Grinding, Dressing, Acoustic Emission |
Abstract : Improvement of monitoring techniques is essential to make the
complex grinding and dressing process more reliable, economical and user
friendly. A system utilizing data fusion from different sensor sources
and AI methods combined with a graphical user interface has been applied
for this purpose. The main task of the grinding monitoring system is the
detection of disturbances and the grinding cycle optimization based on
the AE and power signal. The influence of different dressing parameters
on the AE-signal has been investigated and a dressing monitoring system
is proposed. Reliable data acquisition techniques, which make a
continuous scanning of such wide bandwidth signals possible, have been
applied.
|
|
Coolant induced forces in CBN high speed grinding with shoe nozzles
|
|
F. Klocke (1), A. Baus, T. Beck
|
|
STC G, 49/1/2000, P.241
|
|
Keywords: Grinding, Lubrication, Force |
Abstract : Constantly increasing cost pressures in production as well as
questions of environmental compatibility and the disposal of wastes have
motivated many producers to re-evaluate the application of cooling
lubricants over the past few years. Seen against this background, it is
understandable that industry and research should be concerned with
longer service lives and lower quantities of cooling lubricants. The use
of shoe nozzles in CBN High Speed Grinding is one possible step on the
way to coolant flow reduction in grinding. These nozzles ensure that
most of the lubricant (especially in the case of oil) reaches the
grinding gap, which is the only point where it can help to reduce friction.
Besides reducing the friction, the oil in the grinding gap leads to
coolant induced forces such as those known from hydrodynamic bearings.
These forces can lead to geometrical errors especially when grinding
small workpiece diameter. Therefore this paper starts with a calculation
of the coolant flow which can be fed to the grinding gap without
producing coolant induced forces. Following this, a model for the
coolant induced forces is presented, taking the cutting speed, the
coolant viscosity and the coolant flow into consideration. The paper
ends with results of grinding tests with different coolant flow nozzles
and coolant flow rates.
|
|
An investigation of high speed grinding with electroplated diamond wheels
|
|
T.W. Hwang, C.J. Evans (2), S. Malkin (1)
|
|
STC G, 49/1/2000, P.245
|
|
Keywords: high speed grinding, plated diamond wheel, silicon nitride |
Abstract : The more widespread utilization of ceramics materials for
mechanical components has been inhibited by the high machining cost and
the need to maintain required surface integrity. Single layer
electroplated diamond wheels offer the potential for efficient machining
of ceramics due to their good grit protrusion, safety at high wheel
speeds, and relatively low cost. An investigation was conducted of the
grinding mechanisms, wheel wear, wheel life, and surface integrity for
high speed grinding of silicon nitride using electroplated diamond
wheels at speeds of 85 m/s and 149 m/s. Experimental results are
presented for the grinding forces, radial wheel wear, and surface
roughness, together with microscopic observations of both the ground
surfaces and wheel surfaces. A statistical model is developed to
characterize the wheel topography and its effect on the grinding process
in terms of active cutting grains and wear flat area. Some preliminary
results of acoustic emission monitoring and modulus of rupture (MOR)
strength tests are presented.
|
|
Torsional vibration effects in grinding?
|
|
M.A. Mannan (2), S.J. Drew, B.J. Stone / J.G. Wager (1)
|
|
STC G, 49/1/2000, P.249
|
|
Keywords: Grinding, vibration, chatter |
Abstract : The vast majority of models of vibration in grinding assume that there
are no torsional vibration effects. In a recent doctoral study, it was
found possible to eliminate grinding chatter by changing the torsional
stiffness of the workpiece drive. In that study, a frequency domain
model for the grinding process was developed that included torsional
effects. It was concluded that for the assumed grinding force model,
chatter could be influenced by the torsional characteristics of both the
workpiece and wheel systems. This paper describes experiments conducted
to determine how the grinding force varies with oscillating workpiece
speed and oscillating chip thickness. It concludes with the description
of a time domain model of the grinding process that includes a force
model consistent with the experimental force measurements.
|
|
Simulation of tool-gringind with finite element method
|
|
K. Weinert (1), M. Schneider
|
|
STC G, 49/1/2000, P.253
|
|
Keywords: Grinding, Tool, Finite element method (FEM) |
Abstract : Thermal stress, in particular, is one of the main problems when grinding
cutting tools. If the process temperatures are too high, lasting damage
to the cutting tool can result. The thermal and thermo-mechanical stress
on tools is of major relevance when describing the influences on the
surface near-zone. In this regard the grinding of cutting tools was
modelled with the help of the finite element method (FEM). The FEM
clearly demonstrates some fundamental relationships between the
simulated thermo-mechanical stress and the wear behaviour of the tools
when being used. Furthermore, temperature measurements have shown that
the FEM represents an appropriate means for describing what is actually
going on in the tool during the grinding operation.
|
|
Fabrication of micro carbide tools by ultrasonic vibration grinding
|
|
H. Onikura, O. Ohnishi, Y. Take / A. Kobayashi (1)
|
|
STC G, 49/1/2000, P.257
|
|
Keywords: Ultrasonic vibration grinding, Micro tool, Carbide |
Abstract : This paper deals with the fabrication of micro cylindrical
tools and micro flat drills of ultra-fine grain cemented carbides by
grinding with ultrasonic vibration. The concept of this grinding is to
reduce the grinding forces such that they will not cause any breakage to
the micro tools. The grinding operations are performed using the end
face of an offset grinding wheel. In grinding with ultrasonic vibration,
better results in aspect ratio and tools of smaller diameter than
conventional grinding are obtained. Due to the lower tensile strength of
carbides, grinding under compressive force has made it possible to grind
to a diameter of 11 um with a length of 160 um.
|
|
Grinding ratio and cost issues in magnetic and non-magnetic fluid grinding
|
|
T.H.C. Childs (1), D.J. Moss
|
|
STC G, 49/1/2000, P.261
|
|
Keywords: Ceramic ball grinding, Wear, Process cost |
Abstract : Grinding rates, diamond consumption and grinding ratios are
reported for the magnetic and non-magnetic fluid grinding of silicon
nitride balls with loose grit, and resin-bonded and electro-plated
diamond drive shafts. Diamond consumables costs are assessed and the
grinding ratios are compared with those measured in surface grinding
with the same material combinations, at similar grit loadings.
Resin-bonded diamond drive shafts give the lowest diamond consumables
costs, estimated to become less than £0.05 ($0.08) per ball on process
scale-up, for 10 mm diameter balls reduced to 9.8 mm. Grinding ratios
less than 10, compared to values in surface grinding of more than 100,
are the process's weakness.
|
STC M |
|
Sliding mode controller design for high speed feed drives
|
|
Y. Altintas (1), K. Erkorkmaz, W.-H. Zhu
|
|
STC M, 49/1/2000, P.265
|
|
Keywords: Feed, Drive, Control |
Abstract : An adaptive sliding mode control technique is presented for
the control of high speed feed drives. The proposed control system is
robust against uncertainties in the drive?s parameters, maximizes the
bandwidth within physical limitations, and compensates for external
disturbances such as friction and cutting force. The algorithm is
briefly presented, followed by machining tests conducted with contour
milling of circles and diamond trajectories. The contour errors are
compared against those of a pole placement controller with feedforward
friction and servo dynamics compensation. It is shown that the sliding
mode controller has practical advantages in rapid tuning and
implementation, but requires smooth reference trajectory generation.
|
|
Direct adaptive generalized predictive control. Application to motor drives with flexible modes
|
|
D. Dumur (1), P. Boucher (2), G. Ramond
|
|
STC M, 49/1/2000, P.271
|
|
Keywords: Control, Machine tool, Drives |
Abstract : Predictive control has proved to be an efficient control
strategy, and its application in the motor drives field has provided
good results, even with small sampling rates. However, in case of
important parameters variations, a high level of performance may be
impossible to maintain with a fixed controller, so that an adaptive
version becomes necessary. This paper presents a direct adaptive
generalized predictive control structure, including a least squares-type
strategy for the controller parameters on-line identification, and a
conditional updating test. An application to motor drives with flexible
transmissions is finally developed, taking into account some variations
of inertia.
|
|
Parallel kinematic machines (PKM) ? limitations and new solutions
|
|
G. Pritschow (1)
|
|
STC M, 49/1/2000, P.275
|
|
Keywords: Parallel kinematic machines, Limitations, Improvement |
Abstract : The main advantages of parallel kinematic machines are their
simple designs and common parts. However they also possess some inherent
disadvantages which include limited orientation angles, non-linear force
transmission and stiffness characteristics, a poor ratio of working
envelope to machine size as well as mediocre accuracy. This paper
discusses the factors which contribute to these negative characteristics
and offers new ways to overcome these disadvantages.
|
|
Deterministic metrology of parallel kinematic machines
|
|
V.T. Portman (2)
|
|
STC M, 49/1/2000, P.281
|
|
Keywords: Accuracy, Parallel kinematic machine, Modelling |
Abstract : The deterministic metrology (DM) establishes links between
accuracy parameters of the machine units and a functional accuracy of
the machine itself. An interrelationship between the quasi-static errors
of the PKM and deviations of the points of the nominal surface from the
actual machined surface is considered. PKM-related mathematical models
of the DM (the matrix of the Euler angles, the inverse kinematics, the
Jacobian for a current platform position, etc.)
are formulated. The Gaussian coordinates of a current point of the
machined surface are used to set up the correspondence between the
models and to map the error distribution over the PKM working space. The
DM approach for the PKM is modeled for milling operations and ball-bar
test.
|
|
A simple yet effective approach for error compensation of a tripod-based parallel kinematic machine
|
|
T. Huang, D.J. Whitehouse (1)
|
|
STC M, 49/1/2000, P.285
|
|
Keywords: Parallel kinematic machine, Forward kinematics, Error compensation |
Abstract : This paper presents a simple yet effective approach for the error
compensation of a tripod-based parallel kinematic machine. In this
approach, the forward kinematics is formulated in such a way that the
coordinate of the tool tip in z direction can be explicitly represented
by the dimensional parameters and actuated variables. This enables one
to implement the linear least square method to estimate the kinematic
parameter errors. This approach has been successfully used for the error
compensation of a prototype. The measurements of a test workpiece show
that once the error in the z direction is properly compensated, the
errors in x and y directions can be automatically compensated.
|
|
Design of a spherical motor with three degrees of freedom
|
|
M. Weck (1), T. Reinartz, G. Henneberger, R.W. De Doncker
|
|
STC M, 49/1/2000, P.289
|
|
Keywords: Machine Tool, Drive Technology, Control Technique |
Abstract : In this paper the development of a new spherical motor which
provides multi-coordinate movements in one drive module is presented.
Due to the ever increasing demands on product quality and the need to
machine free form surfaces modern machine tools and robotic devices
require five degrees of freedom. Thus there is the need for new machine
tool concepts and drive technologies. The spherical motor is able to
eliminate most disadvantages of conventional open kinematics consisting
of sequential axes. It is based on a spherical rotor, which is - like a
ball joint - guided in a sphere. Thus three-dimensional movements can be
performed. A high torque in all positions is achieved by permanent
magnets on the rotor and electromagnetic coils in the stator which are
separately controlled by single power converters. Possible applications
are the replacement of a robot hand axis unit or the inte-gration in a
machine tool to perform five axis milling operations. This paper reports
on the development of the mechanical components, the power converter and
control hardware as well as the magnetic design.
|
|
Development of 5-axis control ultraprecision milling machine for micromachining based on non-friction servomechanism
|
|
Y. Takeuchi (1), Y. Sakaida, K. Sawada, T. Sata
|
|
STC M, 49/1/2000, P.295
|
|
Keywords: Ultraprecision milling, 3-dimensional micromachining, Non-friction servomechanisms |
Abstract : The study addresses the development of a 5-axis ultraprecision
milling machine to create tiny 3-dimensional workpieces as well as
microstructures. 3-axis control ultraprecision milling machines allow
microstructures on tiny workpiece surfaces to be manufactured; however
it is difficult to create 3-dimensional workpieces such as very small
heads, statues etc., which will be important in micromanufacturing in
the future. Thus, a 5-axis milling machine consisting of three
translational and two rotational axes has been developed benefitting
from the use of non-friction servomechanisms. 5-axis micromachining was
conducted to create a half cylindrical workpiece. It was found that the
ultraprecision milling machine is accurate enough to machine tiny
3-dimensional workpieces.
|
|
Ultraprecision 6-axis table driven by means of walking drive
|
|
E. Shamoto, H. Murase, T. Moriwaki (1)
|
|
STC M, 49/1/2000, P.299
|
|
Keywords: Feed table, Piezoelectric actuator, Positioning |
Abstract : A new ultraprecision 6-axis table is developed by employing
the principle of "walking drive". The table is driven by nine pairs of
supporting and feeding piezoelectric actuators. It can travel smoothly
over a long stroke of 60 mm in X and Y directions and can also rotate
around C axis, although the stroke of each actuator is extremely small.
Furthermore, the attitude of the table can be controlled by applying
additional commands to the supporting actuators, i.e. the table can be
moved in Z direction and also around A and B axes within short strokes.
The walking table developed in the present research has 6 degrees of
freedom of motion driven simultaneously. It has unique advantages
compared to conventional tables, such as extremely high positioning
resolution, smooth motion, multi-axis motion, direct drive without
conventional guides, no use of lubricant, etc.
|
|
Predicting high-speed machining dynamics by substructure analysis
|
|
T.L. Schmitz / R.R. Donaldson (1)
|
|
STC M, 49/1/2000, P.303
|
|
Keywords: High speed machining, Sub-structure analysis |
Abstract : The practical implementation of high-speed machining (HSM)
requires accurate knowledge of the machine dynamics. We apply receptance
coupling substructure analysis to the prediction of the tool point
dynamic response, combining frequency response measurements of
individual components through appropriate connections to determine
assembly dynamics using simple vector manipulations. This paper shows
that the dynamic response before and after system changes may be
predicted, thus dramatically reducing the number of required
experimental measurements. The application of this technique to the
tuning of tool dynamics for improved stability by overhung length
variation is demonstrated.
|
|
Power and stability limits in milling
|
|
S. Smith (2), W.R. Winfough, H.J. Borchers
|
|
STC M, 49/1/2000, P.309
|
|
Keywords: Milling, Spindle Power Limit, Stability Limit |
Abstract : The metal removal rate (MRR) in milling is typically limited
by the dynamics of the
tool-spindle combination or by the power. If the tool is stiff, the
power is limiting,
and the spindle stalls before chattering. If the tool is flexible, there
is a spindle
speed range where chatter is limiting. Many tools have some spindle
speeds where chatter is limiting and others where power is limiting.
This paper presents a new "power lobe" diagram which is independent of
the workpiece material. Combined with the power curve for the spindle,
this "stable power" diagram defines the achievable MRR for the entire
machine dynamics.
|
|
Actively controlled compliance device for machining error reduction
|
|
K. Matsumoto, Y. Hatamura (1), M. Nakao
|
|
STC M, 49/1/2000, P.313
|
|
Keywords: Machining error reduction, Compliance control, Grinding |
Abstract : Deformation of the tool itself, due to cutting forces, is one
of the major causes of machining error in precision machining. The
authors propose a new solution to the problem that employs an actively
controlled compliance device. By applying 'negative' compliance of the
device, deformation of the machining tool can be compensated, and the
machining error can be reduced to zero. This paper reports our analysis
of the machining process to compensate machining error using negative
compliance. It also evaluates our method through experiments of grinding
silicon wafers and turbine blades.
|
|
A fast analytical method to compute optimum stiffness of fixturing locators
|
|
S. Jayaram, B.S. El-Khasawneh, D.E. Beutel / M.E. Merchant (1)
|
|
STC M, 49/1/2000, P.317
|
|
Keywords: Fixture, Design, Optimization |
Abstract : Machining fixtures are used to rigidly hold and support
workpieces during machining.
The quality of the machined part directly depends on the combined
stiffness of the
workpiece and the fixture. Low fixture stiffness causes poor quality
parts, while large fixture stiffness causes the fixtures to be expensive
and cumbersome. Finite
element models can be used to optimize the fixture stiffness; however
these techniques are computationally expensive for complex workpiece
geometries. This paper develops a fast analytical method for optimizing
fixture locator stiffnesses for workpieces that are more rigid than the
fixture elements. The developed methodology is validated through finite
element simulations and experiments.
|
|
Fuzzy modeling of inverse dynamics for robotic manipulators base on genetic algorithm
|
|
B. Qiao, J.Y. Zhu (1)
|
|
STC M, 49/1/2000, P.321
|
|
Keywords: Genetic algorithm, Fuzzy control, Robotic manipulator |
Abstract : Genetic Algorithm (GA) can be applied to a wide range of
unstructured and nonlinear optimization problems. In this paper a
Progressive Genetic Learning Algorithm (PGLA) is proposed. The main idea
of PGLA is to progressively change the survival environment of gene
according to the converging process of GA. In each operation the
excellent gene schemas are selected and maintained through their
fitness, while the lower fitness schemas are not discarded completely
but put into a pool where mutation is taken place with a high
probability. The proposed PGLA is used to optimize the parameter and
structure of a fuzzy control system. Simulation on a three linked
robotic manipulator. is conducted and its results are worked out.
|
STC O |
|
From a business opportunity identification up to its manufacturing in virtuel enterprises: a reference model and case study
|
|
C.F. Bremer / W. Eversheim (1)
|
|
STC O, 49/1/2000, P.325
|
|
Keywords: Virtual Manufacturing, Life Cycle, Technology Integration |
Abstract : In the recent years the model of Virtual Enterprises has been described
as a new or innovative organisation form for manufacturing enterprises.
Nevertheless there is a lack of a complete reference model of virtual
enterprises that could be largely used and applied. The present paper
describes such a reference model and its application in a project
carried out in Brazil since July 1998, with a group of nine
manufacturing and technology based Small and Medium Enterprises (SME's)
which forms a Virtual Organisation. A Framework has been developed at
the beginning of the project as a structure and guideline for its
creation. In this Framework the Virtual Organisation is considered as a
stable network of enterprises that aim to co-operate among them and
target to create several different Virtual Enterprises. Therefore a
Virtual Enterprise is defined as a Business Opportunity driven
co-operation between existing and independent enterprises. A proposed
reference model (function and information) is then described as well as
its methods, tools and infrastructures. Examples of the methods adapted
or developed are Benchmarking, Business Plan, Competence Matching and
others. In terms of tools an Internet based Competence search has been
developed. Regarding the infrastructures three of them are detailed:
legal, information and cultural.
|
|
Throughput time control in production systems supported by neural networks
|
|
B. Scholz-Reiter, St. Müller / H.P. Wiendhal (1)
|
|
STC O, 49/1/2000, P.331
|
|
Keywords: Production, Control, Neural Network |
Abstract : In addition to the developed buffer inventory control with
neural networks, the suitability of neural networks for control of
throughput time in production systems is examined. A hybrid self
controlling system was developed from this examination, which can be
used in metal-working companies, functioning according to the workshop
principle. A cascade closed loop control structure is introduced for the
control of the throughput time which is supported by the neural
networks. The neural networks influence the release time of orders and
the level of buffer inventory at the work systems, due to the difference
of set-value of throughput time.
|
|
Finite schedule monitoring and filtering in a computer integrated manufacturing environment
|
|
R.G. Wilhelm (2), R. Chandrashekar, R. Sun, M. Hegedus, B. Chu, W.J. Tolone, J. Long
|
|
STC O, 49/1/2000, P.335
|
|
Keywords: Integrated, Scheduling, Monitoring |
Abstract : An efficient and effective method of filtering is described
for reactive scheduling in an integrated manufacturing environment. The
filter evaluates the significance of schedule deviations in
near-real-time and gives a statistical estimate of the importance of
each schedule deviation; Highly important deviations being those that
prevent schedule objectives from being achieved. A typical result from
STC filtering would be an indication that there is a 95%37; probability of
failing to meet the schedule if the resource were to continue working at
the same rate. The technique is well suited for bottle-neck resources
but may be applied to all resources in an enterprise. The filter, based
on statistical throughput control (STC) is compared to past work in DEDS
and reactive scheduling. Model formulation is presented to show
extensions from previous applications of STC for short-term production
control in a CONWIP (Constant WIP) production system. Data requirements
are detailed with reference to Business Object Documents (BODs) defined
by the Open Applications Group (OAG). A summary of the CIIMPLEX
framework is presented to show how the filter is applied.
|
|
New strategies and tools for increasing simulation efficiency
|
|
H. Bley (2), C. Franke, C.C. Wuttke
|
|
STC O, 49/1/2000, P. 339
|
|
Keywords: Simulation, Multifunctional Models, Planning Tools |
Abstract : In recent years, the progress of simulation technology led to
modeling software showing a very high level of perfection and
functionality. However the expense of modeling has held the number of
users lower than original expectations. The central idea to increase
acceptance is the multiple use of simulation models.
Based on this perception, comprehensive strategies have been developed
for three different kinds of simulation projects: small/standardized,
spontaneous and large/long-running projects. These strategies are
supported by tools for planning and implementation of efficient
simulation projects. The methods and tools have been implemented to
prove their feasibility in event-driven material flow simulation.
|
|
Reinforcement learning approaches to biological manufacturing systems
|
|
K. Ueda (1), I. Hatono, N. Fujii, J. Vaario
|
|
STC O, 49/1/2000, P.343
|
|
Keywords: Manufacturing Systems, Machine Learning, Uncertain Environment |
Abstract : The concept of Biological Manufacturing System (BMS) aims at
dealing with unpredictable changes in the external and internal
environments during whole product life cycle, based on
biologically-inspired ideas such as self-organization, learning and
evolution. We previously developed evolution-based and self-organization
models of the floor level that are able to cope with environmental
changes such as system reconfiguration, machine breakdown and unforeseen
production requests. This paper describes reinforcement learning
approaches to the modeling of BMS, in order to deal with the various
kinds of complex global objectives. The effectiveness of the
proposed model is also discussed by simulation with global objectives.
|
|
Self organization of the cellular manufacturing system
|
|
S. Kondoh, Y. Umeda, T. Tomiyama, H. Yoshikawa (1)
|
|
STC O, 49/1/2000, P.347
|
|
Keywords: Cellular manufacturing system, Conceptual layout design, Reinforcement learning |
Abstract : Determining configuration of production facilities is difficult
problem. To solve this problem, the authors introduce the Cellular
Manufacturing System as a rapid prototyping and strategic
decision-making tool for configuring facilities and product task
assignment.
At the conceptual design stage of the cellular manufacturing system,
there is no decision about facility configuration and product or
machining task assignment. The configuration and assignment are
determined by self-organization at the operation stage. This makes it
possible for the cellular manufacturing system to decide strategic
facilities configuration adapting to changing manufacturing requirements.
This paper describes a model of the cellular manufacturing system and
its self-organization algorithm through software simulations.
|
|
Prediction, optimization and functional requirements of knowledge based systems
|
|
B.N. Colding (1)
|
|
STC O, 49/1/2000, P.351
|
|
Keywords: Prediction, Requirement, Knowledge based system |
Abstract : The ability to accurately predict the performance of physical
systems across a large range, using functions of 3 variables z = f(x,y),
depends on the type of mathematical model used. Linear or nonlinear
programming, and statistical models are often inaccurate in describing
the physical problems, and require a large number of data. Forecasting
methods should be based primarily on experimental evidence, coupled with
preferably fundamental laws of nature, using proper functions with
minima and maxima, often contained in physical systems. The paper
describes a function of 3 variables with five constants, which satisfies
the minimum energy principle. It requires 5 accurate experimental or
calculated values achieving reasonable accuracy over a large range of
thefunctional variables. Starting with a brief review of past research
described in this Author's CIRP papers for temperature, tool-life and
cutting force functions, recent developments including system
optimization are reported in the paper. The accuracy of the ascribed
method is compared with the results using other mathematical and
statistical methods. Its use is demonstrated for surface finish
predictions and its relationship to tool-life, applications to
manufacturing cost relationships, to forecasting enterprise sales and
profit with intellectual capital as parameter, ending with a comparison
with a global warming forecasting model.
|
|
Business innovation - innovative teams, competence brokers and beehive structures - in a sustainable work organization
|
|
A. Kjellberg (2), A. Werneman
|
|
STC O, 49/1/2000, P.355
|
|
Keywords: Knowledge Development, Sustainable Organization, Human Factor |
Abstract : New demands on wide and deep knowledge and competence, stress
the need for teams, for 'complete' teams. Innovative teams, working in a
dynamic and temporary structure, will support one of three demands. This
demand is to quickly grasp the 'invisible' market indicators and to
chase information for the purpose of inventiveness.
Technological progress toward a communications and knowledge society is
creating new business opportunities and a future that is difficult to
predict. Increasingly open data systems allowing individuals to trace
and use information at all levels in the company, requires open and
flexible fellow-workers - and Transparency.
To handle variances in demands, products and processes we will, however,
also have to rely on a Sustainable Work Organization. The company core
excellence values and attitudes as well as the vision and the learning
of the organization are like a platform. Platforms are Sustainable Work
Elements.
This paper will also highlight the need for individual, spontaneous and
temporary acting based on Transparency.
|
|
Tolerance analysis and synthesis using Jacobian transforms
|
|
L. Laperriere, H. ElMaraghy (1)
|
|
STC O, 49/1/2000, P.359
|
|
Keywords: tolerances, synthesis, functional requirement |
Abstract : This paper presents a mathematical tool to help the designer
in the difficult task of tolerancing mechanical assemblies. It starts
with the identification of a critical tolerance chain around some
functional requirement of the assembly. A mathematical relationship
which quantifies the effects that possible small displacements of
functional elements in the chain have on the functional requirement is
obtained. This corresponds to the solution of the tolerance analysis
problem. This is expressed as a set of equations in matrix form with a
Jacobian matrix which provides the desired analysis relationship. The
solution to the tolerance synthesis problem is obtained by simply
pseudo-inverting the Jacobian matrix, where small displacements of the
functional element pairs in the chain are expressed as a function of the
desired small displacements of the functional requirement. The paper
presents the procedure for obtaining both the analysis and synthesis
equations. An example is used to illustrate the generation of tolerance
equations. The paper is concluded with a discussion of how the equations
could be used in a statistical tolerancing context using Monte Carlo
simulations.
|
|
Environmental versus conventional planning for machined components
|
|
P.S. Sheng (2) N. Krishnan
|
|
STC O, 49/1/2000, P.363
|
|
Keywords: Environment, planning, machining |
Abstract : A process planning agent is presented, that enables automatic
planning for 3 Axis CNC Machining for minimal environmental impact along
major hazard categories. Utilizing an Internet-based CAD interface, the
planner enables feature (micro) and part (macro) level planning through
the ACIS format, resident machining process models and a multi-criteria
hazard (MCH) assessment tool. The process planner is also designed to
interact with conventional generative planner (optimizing machining time
and quality factors) as an advisory environmental "agent". Remote
feedback to the designer is provided through visual coding via the CAD
interface. Application of the agent to a complex machined component is
presented.
|
|
Efficient NC-programming of multiaxes milling machines through the integration of tool path generation and NC-simulation
|
|
B. Lauwers, J.-P. Kruth (1), P. Dejonghe, R. Vreys
|
|
STC O, 49/1/2000, P.367
|
|
Keywords: Computer Aided Manufacturing (CAM), Simulation, Milling |
Abstract : This paper describes the development of an "extended CAM
system" for multi-axes milling, integrating tool path generation, axes
transformation (postprocessing) and NC-simulation. The system performs
an immediate verification of each generated cutter location and in case
a collision occurs (e.g. between machine and part), it takes the
appropriate action by applying a collision avoidance algorithm.
Different collision avoidance algorithms have been implemented: change
of tool orientation, selection of other machine axes configurations and
simple tool retract. The effect of a tool orientation change on the
quality of the machined surface has been studied in order to define the
range of tool orientations that may be used for collision avoidance.
|
|
Improving high speed flank milling operations in multi-axis machines
|
|
K. Sorby, K. Tonnessen, J.E. Torjusen / F.O. Rasch (1)
|
|
STC O, 49/1/2000, P.371
|
|
Keywords: Flank milling, High speed milling, Optimization |
Abstract : Flank milling is an efficient method for machining of ruled
surfaces generated by straight ruling lines. The method is also
interesting with respect to general free form surfaces. The geometric
cutting conditions in flank milling, characterized by a small radial
depth-of-cut to diameter ratio, leads to the possibility for use of high
speed technology.
High speed machining will give a high material removal rate and
relatively low cutting forces, which is important in order to reduce the
deflections of the cutting tool in flank milling. Typical applications
for high speed flank milling can be found in the aerospace industry
where a large amount of the components are thin-walled and complex
shaped, and have to be manufactured within narrow tolerances. Besides,
the materials are generally difficult to machine.
Introductorily, the paper presents the technological aspects of flank
milling, with focus on selection of cutting tool, cooling/lubrication,
and machining data. The approximation of general free form surfaces by
ruled surfaces is also discussed.
A new method for optimization of the economy in flank milling is
presented. The method is based on a tool life model, a cutting force
model, cost data, and machine tool limitations related to spindle speed
and feed rate. Such limitations are especially relevant for large
machine tools with rotating axes. The parameters of the models for tool
life and cutting force are experimentally determined for machining Greek
Ascoloy by use of coated carbide tools. The optimization model is
demonstrated by examples from the aerospace industry.
|
|
Incremental supervised learning of cutting conditions using the fuzzy ARTMAP neural network
|
|
M.W. Park, B.T. Park, H.M. Rho (2), S.K. Kim
|
|
STC O, 49/1/2000, P.375
|
|
Keywords: CAPP, Cutting Conditions, Neural Network |
Abstract : As a part of an effort to systematize operation planning for
cutting processes, the fuzzy ARTMAP neural network has been applied to
model the process of selecting cutting conditions and subsequently to
learn cutting conditions for training the model. The fuzzy ARTMAP neural
network is capable of incremental supervised learning, which enables the
model to be reinforced continually and efficiently. In addition, a new
algorithm called the replacement algorithm is proposed. When new cutting
conditions that are more effective for a certain circumstance are
obtained, the proposed algorithm deletes the old information learned,
and then makes the network learn the better ones. Examples of decisions
of cutting conditions using the fuzzy ARTMAP neural network and the
replacement algorithm are provided and discussed.
|
|
A concurrent-engineering approach toward the online adaptive control of injection moulding process
|
|
K.K. Wang (1), J. Zhou
|
|
STC O, 49/1/2000, P.379
|
|
Keywords: Computer Adaptive Control, Concurrent, Molding |
Abstract : Injection molding is the most effective process to produce
plastic parts of complex shape to the highest precision at the lowest
cost. Considerable progress has been made over the last two decades in
modeling and simulation of the molding dynamics. However, due to complex
material properties and other uncontrollable disturbances, consistency
of part quality cannot be assured in production. As a result, an
off-line Statistical Process Control (SPC) scheme has to be established
which can be costly. This paper presents a new approach to the problem.
Based on the concept of Concurrent Engineering, we make full use of the
power of simulation for the design of the part, the mold, and setting up
process control parameters automatically. The control system consists of
a feed-forward loop and three feedback loops with numerous associated
sensors in each loop. With an online PC and a smart part-quality sensor,
the system can control the variation of part weight (one measure of
quality) ten times better than existing methods.
|
|
Predictive monitoring and control of the cold extrusion process
|
|
S. Spiewak (2), R. Duggirala, K. Barnett
|
|
STC O, 49/1/2000, P.383
|
|
Keywords: Extrusion, Predictive Control, Press |
Abstract : Cold extrusion and forging processes require significant
improvements in productivity to ensure the continued competitiveness of
press manufacturers and users. Current average productivity rates are
less than 60 percent, while the lost production capacity is mainly due
to equipment failures and unreliable processes control. A group of
companies representing press manufacturers and users collaborated within
National Center of Manufacturing Sciences to diagnose the common
problems and recommend solutions. Major findings presented in this paper
pertain to identifying and eliminating root causes of lost production in
an automated facility running multiple high tonnage mechanical presses.
Example results that indicate the feasibility of predictive process
control are included.
|
|
Integrated condition monitoring and fault diagnosis for modern manufacturing systems
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Z.D. Zhou, Y.P. Chen, J.Y.H. Fuh, A.Y.C. Nee (1)
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STC O, 49/1/2000, P.387
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Keywords: Condition monitoring, Failure diagnostics, Intelligent manufacturing system |
Abstract : A multi-sensor and multi-parameter condition monitoring and
fault diagnosis system is designed and implemented for modern
manufacturing systems, such as flexible manufacturing cells and systems.
The overall hardware and software designs of this system, together with
the functional sub-systems, are presented. This implemented system
monitors power, vibration, temperature and pressure of the drives and
spindles with a total of 72 diagnostic features and uses a cost-weighted
function to identify diagnostic solutions with the lowest cost.
Condition monitoring, data acquisition, knowledge acquisition and
representation, as well as the diagnostic reasoning strategy of the
knowledge-base system are presented in detail. The system was
implemented and tested in a textile plant with satisfactory results.
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STC P |
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Design of a high-accuracy CMM based on multi-lateration techniques
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E.B. Hughes, A. Wilson, G.N. Peggs (1)
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STC P, 49/1/2000, P.391
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Keywords: Coordinate Measuring Machine, Laser Interferometry, Accuracy |
Abstract : To address the industrial requirement for the calibration of
two-dimensional and three-dimensional artefacts, NPL is developing a new
primary CMM with a target uncertainty of 300 nm (k = 1.96) within a
cubic working volume of side 600 mm. This CMM is based on the principle
of multi-lateration whereby spatial coordinates are determined solely
from measurements of displacement of a moving probe relative to a
number, probably as many as eight, of fixed measuring stations. A
prototype measuring station has been designed, built and tested. The
design of the measuring station has been optimised to minimise
uncertainties due to beam steering. This paper describes the design of
the measuring station, presents an evaluated uncertainty and outlines
test results obtained from the prototype system.
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Assesment of uncertainties in dimensional metrology by Monte Carlo simulation: proposal of a modular and visual software
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H. Schwenke, B.R.L. Siebert, F. Wäldele, H. Kunzmann (1)
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STC P, 49/1/2000, P.395
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Keywords: Uncertainty, Simulation, Software |
Abstract : An accurate assessment of the uncertainty associated with
measured dimensions is increasingly important in industrial routine. The
GUM [1] provides definitions and suggests a standard procedure for the
assessment of uncertainties. However, this procedure is tedious or even
impossible in the case of complex dimensional meas-urements. This paper
demonstrates, that the Monte Carlo simulation allows a straightfor-ward
and accurate as-sessment of uncertainties in complex dimensional
measurements.
A modular software concept is proposed which allows the set up of the
model function for such complex measurement processes by concatenation
of modules from a library.
A validation of the method is provided by comparison measurements.
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A method for optical CMM calibration using a grid plate
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G.X. Zhang (1), J.Y. Fu
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STC P, 49/1/2000, P.399
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Keywords: Error Calibration, Optical CMM, Algorithm |
Abstract : The reduction in feature size on microchips has generated an
urgent need to improve the accuracy of lithography machines and optical
CMMs. Error calibration and compensation of these machines can meet this
need. The geometry of an optical CMM or a lithography machine can be
calibrated in two dimensions by measuring an uncalibrated reversible
grid plate in three different positions. In the initial position the
plate is aligned with the machine coordinate system. Next it is reversed
about the Y axis of the machine. In the third position the grid plate is
rotated 90 degrees about the Z axis of the machine. In order to
determine the scale error (establish the metric) one of the machine axes
should be calibrated using a stabilized laser interferometer. This paper
presents a new and simple algorithm for obtaining the compensation data
from grid plate measurements assuming that one axis has been calibrated
with a laser. Both computer simulation and experiments have been
performed to access the effectiveness of the proposed method.
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A study on the development of a three dimensional linear encoder system for in-process motion error calibration and compensation of a machine tool axes
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K. Yamazaki (2), U. Mueller, J. Liu, J. Braasch
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STC P, 49/1/2000, P.403
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Keywords: Measuring instrument, Optoelectronic sensor, Motion calibration, |
Abstract : Precision machine tools require in-process measurement of
volumetric accuracy for machining and calibration. This paper describes
the development and evaluation of a volumetric linear encoder for
measuring the on-axis volumetric motion accuracy. The encoder is based
on three cross-grid gratings as measurement bodies and a sensor-head
consisting of six optical sensing elements. The encoder uses a
non-touching interferential scanning principle that allows the
measurement of six axial displacements. The displacement information is
interpolated by an application specific integrated circuit (ASIC) and
transformed in three volumetric linear and angular displacement. The
prototype encoder was evaluated to verify its effectiveness under
laboratory conditions and in the factory.
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An advanced ceramic optical diamond turning machine ? design and prototype development
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J.P.M.B. Vermuelen, P.C.J.N. Rosielle, P.H.J. Schellekens (1)
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STC P, 49/1/2000, P.407
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Keywords: High-precision design, Ceramic laminate material, Diamond turning |
Abstract : A new high precision optical diamond turning machine was
designed and developed, having a vertical axis and all ceramic slides,
performing submicrometer accuracy (0.3 micrometer without software error
compensation) and mirror surface quality (6 nm Ra). In view of improving
repeatability, basic fundamentals like kinematic design, the Rule of
Abbe, high stiffness structural loop design, hardware compensation of
thermal expansion, force compensation and (thermal) symmetry were built
in throughout the machine. The vertical axis machine with all aerostatic
slides and linear direct drives differs significantly from conventional
lathes in both design at the component level and in material
utilisation. By the development and application of ceramic laminate
composite materials, the specific stiffness of functional moving parts
was increased by a factor of three compared to steel, aluminium and
granite, and furthermore, viscoelastic material damping was incorporated
within the structural material itself. Consequently, the dynamic
behaviour of the machine was considerably improved having the first
natural frequency at 200 Hz. The work in this paper that was carried out
in a Ph.D. project, focuses on machine design aspects showing analytical
and experimental results and design synthesis.
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Novel multi degree of freedom piezoelectric actuators
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J.A.G. Knight / J.R. Crookall (1)
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STC P, 49/1/2000, P.411
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Keywords: Actuator, Piezoelectric, Bearing |
Abstract : This paper considers the design of a piezoelectric
multi-degree-of-freedom actuator/sensor by introducing the concept of an
active kinematic pair in which one or both links are made from
piezoactive material which through the application of suitable
excitation enable the generation of static displacements, quasi-static
or resonant oscillations resulting in the generation of forces or torque
in the contact zone between links. These forces or torques lead to the
generation of motion of one link relative to the other. Several novel
actuators have been designed, developed and realised based on an active
kinematic pair. Different configurations are considered in the paper
including three arrangements for two degree of freedom active bearings
and a three degree of freedom robot eye. The performance of these
actuators has been established by testing and evaluation and the paper
presents these results in terms of number of sectioned electrodes,
voltage-angular velocity and frequency-angular velocity, response time
and accuracy, and resolution of movement. Based on the extensive
experimentation a design methodology for actuators configured from
active kinematic pairs is presented.
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Angle metrology of dispersion prisms
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W.T. Estler (2), Y.H. Queen
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STC P, 49/1/2000, P.415
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Keywords: angular measurement, index of refraction, calibration |
Abstract : We present a new technique for calibrating the apex angles of
dispersion prisms, which are used in the measurement of the index of
refraction of optical glasses. The new method requires only a phase
measuring interferometer, together with an electronic autocollimator,
and eliminates the need for a rotary or indexing ta-ble. The apex angles
of a nominally equilateral prism of fused silica were measured and the
results compare favorably with a traditional calibration using an
indexing table comparator.
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STC S |
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Comparison of conventional light scattering and speckle techniques concerning an in-process characterisation of engineered surfaces
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P. Lehmann, G. Goch (2)
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STC S, 49/1/2000, P.419
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Keywords: Scatter, Roughness, In-process |
Abstract : It is well known that several features of engineered surfaces
can be determined by light scattering techniques. However, the
characterisation of surface icrotopography by scattered light sometimes
only yields a qualitative ssessment or does not directly correspond to
common roughness parameters. The latter shortcoming may even lead to
ambiguity, so that these techniques are hardly accepted for industrial
quality inspection. Nevertheless, the technological progress in the
field of optoelectronics (laser diodes, CCD- and CMOS-cameras, digital
image processing) allows a compact realisation of novel arrangements. In
this contribution, light scattering and speckle techniques for a
measuring range from 1 nm to about 10 µm (rms-roughness) will be
introduced. Conventional light scattering methods relevant to industrial
applications are known as "angle resolved scattering" (ARS) and
diffuseness measurement. The speckle techniques include the method of
polychromatic speckle autocorrelation and the doubly scattered light
approach, which have been recently developed by the authors. The
different parametric methods will be compared with respect to their
in-process capabilities and the correlation between optical output
parameters and statistical parameters of the surface profile under
investigation. Furthermore, it will be shown that 3D-quantities of
engineered surfaces can be obtained from the measuring data.
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3D micro-profile measurement using optical inverse scattering phase method
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A. Taguchi, T. Miyochi, Y. Takaya, S. Takahashi, K. Saito (2)
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STC S, 49/1/2000, P.423
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Keywords: Micro-profile, Optical measurement, Nano-technology |
Abstract : With the advance of the nano-technology, especially
micromachining, in-process measurement techniques for micro-machined
profiles in the submicron order are increasingly required. However,
conventional Scanning Probe Microscopes (SPM) come with numerous
problems in applications to in-process measurement. In this paper, we
propose a new optical measuring method which can be applied to the
in-process measurement of three-dimensional micro-profiles with accuracy
in the nanometer order. The optical inverse scattering phase method
offers the advantage of measuring a three-dimensional profile within the
whole area illuminated by the laser beam simultaneously. No scanning
process is required. Employing Fourier phase retrieval algorithm,
three-dimensional micro-profiles are reconstructed from only the
measured Fraunhofer diffraction intensity. Computer simulations and
actual measurements were performed for the verification of the proposed
method. The result obtained in the measurement for an ultra precision
grid plate, which has rectangular pockets 44nm deep at intervals of
10mm, shows the validity of this method.
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Measurement and topography characterisation of surfaces produced by selective laser sintering
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P.M. Lonardo (1), A.A. Bruzzone
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STC S, 49/1/2000, P.427
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Keywords: Laser sintering, Optical measurement, Surface topography |
Abstract : Selective Laser Sintering (SLS) permits to manufacture
physical models, suitable to be used as sand moulds in the casting
processes. SLS presents some technological limits as regards the
dimensional precision and surface roughness, which require an accurate
assessment. Unfortunately contact methods are not able to carry out
these measurements.
This paper investigates the possibility of using a new non-contact
instrument based on conoscopic holography to measure both microgeometry
and macrogeometry of SLS samples. The reliability of measures and its
influence on roughness parameters is discussed. A procedure for
characterising and identifying the sample edges is introduced.
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Properties of honed gears during lifetime
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H.K. Tönshoff (1), T. Friemuth, C. Marzenell
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STC S, 49/1/2000, P.431
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Keywords: Gear honing, Workpiece property, Fatigue life |
Abstract : Properties of tooth flanks such as roughness, surface
topography, residual stresses, material structure and hardness influence
the lifetime of a gear running under load. These properties have been
generated by the gear's finishing process, but they do not remain
constant when the gear comes into mesh. This paper describes the
alterations of the tooth flanks' properties with the example of hardened
gears that were finished by gear honing with electroplated tools. The
results enlarge the knowledge of fatigue mechanisms that lead to
failures of gears when high loads persist over a long running time.
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Generation of reaction layers on machined surfaces
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E. Brinksmeier (1), A. Walter
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STC S, 49/1/2000, P.435
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Keywords: chemical surface integrity, cooling lubrication, machining |
Abstract : Machined surfaces are influenced by the generation of reaction
layers resulting from the formulation of the metalworking fluid.
Coolants reduce friction at the tool/surface interface and significantly
influence the heat dissipation in machining operations and the
generation of the surface layer. Nowadays, machining processes are
evaluated with respect to the forces, grinding wheel wear, surface
roughness, surface integrity, residual stresses, process stability, and
reproducibility of the work result. Considering the chemical performance
of the used coolants, it is necessary to gain additional information
about the chemical mechanisms in the contact zone in order to evaluate
the surface quality.
This paper deals with investigations of the influence of machining
processes on the generation of reaction layers. These layers were
generated by using certain coolant additives in machining. For
industrial applications it is very interesting to know which effects
different coolant additives have on the workpiece surface, because it is
well known that adsorption and reaction layers of machining processes
hinder thermochemical heat treatment.
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Nano-machining instrument for nano-cutting of brittle materials
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W. Gao, R.J. Hocken (1), J.A. Patten, J. Lovingood
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STC S, 49/1/2000, P.439
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Keywords: Nano-cutting, instrument, brittle material |
Abstract : This paper presents a nano-machining instrument, which was
developed for conducting nano-cutting experiments especially on brittle
materials.
A PZT tube scanner is employed to accomplish a maximum depth of cut of 4
micrometers with 0.1 nm resolution, and a length of cut of more than 20
micrometers. The depth of cut is feedback controlled by using the output
of a capacitance probe. The flexural stiffness and the axial stiffness
of the instrument were designed to be 6 x 106 N/m and 7 x 107 N/m,
respectively.
There are two force sensors to measure thrust and cutting forces with a
resolution of sub-milliNewtons. The sample is kinematically mounted on
the PZT scanner, and the tilt of the sample can be adjusted precisely.
Experimental results of nano-scratching and Nano-cutting on single
crystal silicon will be presented.
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Planar ion channeling study of subsurface damage in polished CdS
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D.A. Lucca (1), C.J. Maggiore, M.J. Klopfstein
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STC S, 49/1/2000, P.443
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Keywords: Surface, Polishing, Sub-surface damage |
Abstract : Planar ion channeling has been used to investigate the near
surface lattice disorder of minimally damaged surfaces of CdS produced
by polishing. Surfaces produced by mechanical and chemomechanical
polishing were examined along the { } and { } planes of (0001) oriented
crystals using incident beam energies of 1 and 2 MeV. Results were
compared to those previously obtained under axial channeling conditions.
Planar channeling was seen to exhibit increased sensitivity to near
surface damage and enabled the identification of damage beyond that
detectable with axial channeling for a 1/4 µm diamond abrasive
mechanically polished surface.
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An analysis of surface properties of hetero-epitaxially grown SiC surface on Si substrate elements
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N. Moronuki, Y. Furukawa (1)
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STC S, 49/1/2000, P.447
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Keywords: Silicon carbide, Mirror surface, Deposition process |
Abstract : The molecular beam epitaxy process can produce single crystal
and smooth surface at atomic level as well as synthesizing the desired
material by supplying the multiple materials on substrates. This paper
deals with an application of the hetero-epitaxial process of silicon
carbide (SiC) on silicon (Si) substrate, and aims to make clear the
attainable surface roughness and its properties. It was found that the
steep pits were formed during the carbonization process before the
epitaxy and that they strongly affected the final roughness. The
attainable roughness was 0.4nm rms. Finally, the applicability to
toroidal mirror optics was discussed.
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