CIRP ANNALS 1998
|
|
|
|
|
STC A |
|
Qualification of standard industrial robots to cope with sophisticated assembly tasks
|
|
G. Reinhart (2), R.-G. Gräser, R. Klingel
|
|
STC A, 47/1/1998, P.1
|
|
Keywords: assembling, on-line compensation, robot accuracy |
Abstract : New fields of application such as low-tolerance laser welding, micro and
precision assembly or measurement technology are to be achieved by
standard industrial robots for higher economic efficiency. However
actual implementation fails due to the temperature drift caused by time
variable internal and external sources of heat.
A compensation method for fast online-correction of the time variable,
thermal robot behaviour is introduced. This method is based on measuring
the temperature-caused deviations and subsequent compensation by
software during operation. The presented results show that the
temperature caused deviations are minimized to the level of the system
inherent repeatability. Hence constant position accuracy of robots can
be achieved.
|
|
Collision free control of a multi-arm testing robot
|
|
H. Terada, H. Makino (1)
|
|
STC A, 47/1/1998, P.5
|
|
Keywords: robot, circuit test, multi-arm |
Abstract : A multi-arm testing robot system has been developed in which quadruple
SCARA arms move simultaneously in a single working area. To avoid
collision, the "occupied quadrant" algorithm is developed. Every
quadrant is assigned for each arm and the testing points are selected as
there are positive margins between the quadrants. Together with the
linear continuous path control in the Cartesian space, with overlapped
horizontal and vertical motion, and with simultaneous motion control for
all arms, high speed collision-free movement was obtained. The minimum
tact time was proved to be less than 0.1 second per moving distance of 8mm.
|
|
A concept of an intelligence fuzzy control for assembly robot
|
|
P.B. Petrovic, V.R. Milacic (1)
|
|
STC A, 47/1/1998, P.9
|
|
Keywords: robotic assembly, compliance, fuzzy control |
Abstract : Active accommodation of robotic manipulator in assembly applications is
considered. Mechanical impedance control concept has been chosen for
development an intelligent controller for assembly robots, where target
impedance appears as a control variable. Basic assumption for successful
part mating process according to part mating theory is mechanical
isotropy of support system. Consequently, target impedance should be
adopted as isotropic. The main problem appearing here is complex
analytical formulation of isotropic target impedance and uncertainty of
parameters related to the robot and environment model. To overcome this
problem an adaptive fuzzy model of isotropic target impedance is
proposed. The fuzzy model is incorporated into general impedance control
law form, to obtain new fuzzy-impedance control law. Proposed control
law has been verified by computer simulation.
|
|
Dexterous assembly - manipulation of a compact array of objects
|
|
Y. Aiyama, T. Arai (1), J. Ota
|
|
STC A, 47/1/1998, P.13
|
|
Keywords: assembly machine, compliance, manipulator |
Abstract : It is often said that a product has few advantages in market if an
assembly line of the product can be easily mechanized. Operations turn
more dexterous in advanced manufacturing systems. In this paper, a
manipulator with three fingers handles a box in a compact array of six
boxes. First one of the fingers tumbles one box to make two side faces
free from the obstacles. Then the other two grasp both the sides and
pick it up. To fulfill such a sequence of dexterous manipulations onto
various objects, the design of compliance of the fingers is essential.
The paper deals with design of compliance of each finger and with
planning of its motion. The proposed methodology is experimented by the
robot with three fingers, each of which has three direct drive joints.
|
|
Multivariate analysis and evaluation of adaptive sheet metal assembly systems
|
|
D. Ceglarek / M. Szafarczyk (1)
|
|
STC A, 47/1/1998, P.17
|
|
Keywords: flexible assembly, error compensation, dimensional error |
Abstract : The flexibility of sheet metal assembly processes is one of the most
critical issues in the design stage of assembly systems. Currently in
the automotive industry, flexibility and adaptability of assembly
systems are mainly considered as the capability to assemble a family of
products. The notion of assembly system flexibility, as understood from
the point of view of error compensation by upstream processes, has not
been widely researched. This paper presents a systematic method of
flexible/adaptive assembly system evaluation, based on its ability to
compensate for part dimensional variability caused by upstream
processes. This allows for the expansion of the present design for
manufacturability approaches by applying multivariate analysis and
fixture diagnostic techniques. The proposed method was applied to
evaluate a flexible assembly system at a US manufacturing plant.
|
|
Alternative placement systems for three dimensional circuit boards
|
|
K. Feldmann (1), S. Krimi
|
|
STC A, 47/1/1998, P.23
|
|
Keywords: assembly, robotic, flexible manufacturing |
Abstract : The three dimensional circuit board technology leads to advantages and
new special challenges concerning electronics assembly. Two different
placement systems were realized at the FAPS institute. The first concept
was developed to extend the limits of a Cartesian Placement System. An
advanced module for handling the Molded-Interconnect-Device-Technology
(MID) in the working space of a SMD assembling system, as well as the
use of a pipette with an additional axis, make the 3-dimensional
assembly of components into MID possible. The second concept is a Robot
Placement System, which consists of hardware components like a six axis
robot, a tool changing system, a transport system, moving feeders and a
vision system. A critical point in surface mounted technology is the
necessary accuracy in cantering the SMD to the pipette and the accurate
placement of components. This is realized with the use of vision
systems. Thereby, a new strategy for failure compensation was developed.
A way to optimise the control structures and kinematic of MID placement
systems is the use of modern simulation based development and test
systems, which provide facilities to perform structural analysis,
collision detection, cycle time calculation as well as off-line
programming capabilities.
|
|
Simulation of the soldering process
|
|
J. Niemeier, G. Seliger (2)
|
|
STC A, 47/1/1998, P.27
|
|
Keywords: soldering, computerized simulation, thermal analysis |
Abstract : The expenditure for planning and setting-up of automated facilities for
single point soldering is currently very high, since adjusting of
process parameters is based on the operator's experience. A process
model has been developed which describes the process of single point
soldering and allows predictions of its behaviour. The model lakes into
account the heat flow into the joint and inside the joint. The model was
implemented as a software-tool for computing the temperature profiles in
different sectors of the solder joint. With this model the planning and
setup time of single point soldering facilities is significantly reduced
and control software can be developed.
|
STC C |
|
Catastrophic tool failure detection based on acoustic emission signal analysis
|
|
K. Jemielniak (2), O. Otman
|
|
STC C, 47/1/1998, P.31
|
|
Keywords: cutting, tool condition monitoring, acoustic emission |
Abstract : Acoustic emission (AE) signal analysis is considered to be a very useful
mean of on-line tool breakage detection. Many publications have
proclaimed that catastrophic tool failure (CTF) causes an eminent peak
in the AE signal. Therefore the magnitude of the AE_RMS signal has been
considered as a measure of the CTF. While strong bursts of AE signals
similar to those arising from the CTF can be generated by tool
engagement and disengagement in interrupted turning, this measure was
found to be not always sensitive to the CTF. The aim of this paper is to
present a method of the CTF detection in turning which uses symptoms
other than the direct AE_RN ,_S signal value taking into considerations
the likely bursts that can be generated due to interruption. The method
is based on the statistical analysis of the distributions of the AER_MS
signal. The kurtosis and the sum of the (3 distribution parameters r and
s were the main measures employed. They were found to be highly
sensitive to tool chipping and breakage and have given promising results
with regard to CTF detection.
|
|
An automatic system for elaboration of chip breaking diagrams
|
|
J.L. Andreasen, L. De Chiffre (2)
|
|
STC C, 47/1/1998, P.35
|
|
Keywords: turning, chip breaking, automatic recognition |
Abstract : A laboratory system for fully automatic elaboration of chip breaking
diagrams has been developed and tested. The system is based on automatic
chip breaking detection by frequency analysis of cutting forces in
connection with programming of a CNC-lathe to scan different feeds,
speeds and cutting depths. An evaluation of the system based on a total
of 1671 experiments has shown that unfavourable snarled chips can be
detected with 98%37; certainty which indeed makes the system a valuable
tool in chip breakability tests. Using the system, chip breaking
diagrams can be elaborated with a previously unattainable productivity
and objectivity.
|
|
The temperature of a single crystal diamond tool in turning
|
|
T. Ueda, M. Sato, K. Nakayama (1)
|
|
STC C, 47/1/1998, P.41
|
|
Keywords: ultra-precision turning, temperatures, single crystal diamond |
Abstract : The temperature on the rake face of a single crystal diamond tool in
precision turning is investigated experimentally and theoretically. The
infrared rays radiated from the contact area between the chip and rake
face, and transmitted through the diamond tool, are accepted by a
chalcogenide fiber and led to a two-color detector which consists of
InSb and HgCdTe detectors. The temperature distribution in the tool and
in the workpiece is calculated numerically using FEM. From these
results, the maximum temperature on the rake face is found to be
approximately 190°C for aluminum and 220°C for copper at a cutting speed
of 620 m/min. The temperature increases with the increase of cutting
speed for the range of cutting speeds investigated.
|
|
Diamond cutting of silicon with nanometric finish
|
|
F.Z. Fang, V.C. Venkatesh (1)
|
|
STC C, 47/1/1998, P.45
|
|
Keywords: mirror surface, diamond cutting, brittle material |
Abstract : Micro-cutting is a viable alternative to grinding and polishing
techniques in the fabrication of high quality brittle materials. Using
different diamond tools with rake angles of 0 degree and -25 degree at
different cutting speeds, taper cutting experiments were carried out
with increasing depth of cut on silicon. The grooves formed were
analysed by Scanning Electron Microscopy and Optical Measurement
Inspection System. Topographic details were studied using Atomic Force
Microscope. For turned silicon surfaces with roughness value of Ra=23.8
nm and Rmax=140 nm, mirror surfaces of 1 nm roughness were achieved
repeatedly by micro-cutting. The integrity of the resulting surfaces
were then studied in detail by using Atomic Force Microscopy and
Scanning Electron Microscopy. The results prove that the micro-cutting
mechanism, proposed in theory, is justified in actual material removal
in the range of nanometers.
|
|
A model for simulation of vibrations during boring operations of complex surfaces
|
|
J.F. Rigal, C. Pupaza, C. Bedrin (2)
|
|
STC C, 47/1/1998, P.51
|
|
Keywords: boring, simulation, stability |
Abstract : The dynamics of the cutting process, as well as the behaviour of the
piece and the tool, have a strong influence on the quality of the
machined surface, particularly in the boring operations of complex
surfaces with thin walls.
On the basis of a parameterised model of the tool-material interaction,
a linear FEM model describing the behaviour of the workpiece, tool and
their contact is presented. The frequency responses are processed and
the simulation extends with a mixed procedure (FEM analysis and
simulation using Matlab). The purpose is to characterize the stability
conditions of the cutting process.
|
|
On the dynamics of high-speed milling with long, slender endmills
|
|
M.A. Davies, B. Dutterer, J.R. Pratt, A.J. Schaut / J.B. Bryan (1)
|
|
STC C, 47/1/1998, P.55
|
|
Keywords: milling, vibration, modelling |
Abstract : Tool deflections of high length-to-diameter ratio endmills are measured
with capacitance probes during high-speed milling and compared with the
predictions of regenerative chatter theory. Poincaré sectioning (once
per revolution sampling) techniques are introduced as a new means of
characterizing and identifying chatter. The regenerative chatter theory
seems to accurately predict the stability of high-immersion slotting
cuts: however, undesirable vibrations observed in partial immersion cuts
seem inconsistent with existing theory. The practical utility of
in-depth knowledge of the stability behaviour of long endmills is
demonstrated by the high-speed machining of an example component using a
dynamically tuned tool.
|
|
Milling titanium compressor blades with PCD cutter
|
|
E. Kuljanic (1), M. Fioretti, L. Beltrame, F. Miani
|
|
STC C, 47/1/1998, P.61
|
|
Keywords: milling, titanium, diamond |
Abstract : This paper investigates the possibility of finishing milling of titanium
alloy TiAI6V4 compressor gas turbine blades with polycrystalline cubic
diamond POD cutter that can be used successfully for milling "slim" -
low stiffness - blades. The tool life of POD cutter was very long T=381
minutes while surface roughness of the machined surface was low and the
geometrical accuracy was satisfactory. A suitable inclination of the
cutter axis to the surface has been determined. A basic consideration of
milling titanium based alloy with PCD cutter and an analysis and
discussion of the chip formation are presented. Better results are
obtained when cooling refrigerant was applied. Finishing milling of
titanium alloy TiAI6V4 "slim" blades with PCD cutter is promising.
|
|
Improved cutting processes with adapted coating systems
|
|
F. Klocke (2), T. Krieg, K. Gerschwiler, R. Fritsch, V. Zinkann, M. Pöhls, G. Eisenblätter
|
|
STC C, 47/1/1998, P.65
|
|
Keywords: cutting, coating, process improvement |
Abstract : Since the introduction of coated metal cutting tools, there has been
continuous development and improvement of substrates and coatings.
These improvements are invariably aimed at better resistance to the
stresses involved in specific cutting tasks like interrupted cutting,
machining of adhesive materials or hard and dry machining. Examples of
improved performance coatings include multilayer hard thin films or
composite hard/soft coatings. The paper documents fundamental research
work indicating how various advanced coatings affect contact conditions
and wear mechanisms during the machining of different ferrous and
non-ferrous metals. Layers formed during the cutting process are also
considered. Results are supplemented by application-oriented experiments
during a number of cutting processes.
|
|
Experimental and FEM analysis of the fatigue behaviour of PVD coatings on HSS substrate in milling
|
|
K.-D. Bouzakis (1), K. Efstathiou, N. Vidakis, D. Kallinikidis, S. Angos, T. Leyenderker, G. Erkens,
|
|
STC C, 47/1/1998, P.69
|
|
Keywords: PVD coatings, fatigue, HSS |
Abstract : The new generation of single and multilayer thin hard coatings ensures
the improved tool life and the enhanced superficial quality of the
workpiece material. However, in interrupted cutting processes such as in
milling, the tool coating life time may be limited by fatigue phenomena.
Nowadays, the fatigue performance of coatings is quantitatively
predictable. In the present paper, the fatigue prospects of PVD coatings
on High Speed Steel (HSS) inserts are examined experimentally and
analytically in milling. The coating failure is depicted by means of
Scan Electron Microscopy (SEM) investigations and Energy Dispersive
X-ray (EDX) microspectral analyses. The cutting process is simulated by
means of a Finite Elements Method (FEM) parametric model and the stress
results illustrate a fatigue prediction that fits to the experimental
ones. Data required for the FEM simulation, such as material properties,
cutting forces, chip compression ratio etc. are determined experimentally.
|
|
A contribution to the study of the cutting mechanisms during high speed machining of hardened steel
|
|
G. Poulachon, A. Moisan (1)
|
|
STC C, 47/1/1998, P.73
|
|
Keywords: chip formation, hard turning, modelling |
Abstract : A 1000r6 steel with a hardness HRC62 was machined. Quick stop tests were
carried out to observe the different chip formation mechanisms. A limit
was found between the shearing or cracking chip formation.
Experimentations for the selected steel at HRC62 were led at various
cutting speeds and feed rates. The "saw tooth chips" obtained were
examined geometrically and metallurgically on longitudinal midsections.
Relations have been established between the chip geometry and the
cutting conditions. A theoretical study on the chip shape was made, in
particular about its thickness. The friction stick slip velocities, as
the segment apparition frequency were calculated. Each stage of the chip
formation could be observed on each micrography of Q.S.T, especially the
crack initiation.
|
|
The mechanism of chip formation when hard turning steel
|
|
M.C. Shaw (1), A. Vyas
|
|
STC C, 47/1/1998, P.77
|
|
Keywords: cutting, chip formation, hard turning |
Abstract : Steels having a hardness of H_RC 60 or greater are presently being
finished by turning instead of grinding. This is usually done using a
polycrystalline cubic boron nitride insert having a rather large nose
radius on a very rigid machine at a relatively high cutting speed. In
order to understand this process it is important that the sequence of
events occurring in the formation of the unique type of chip involved be
correctly identified. Experimental evidence to this end is presented and
discussed in fundamental terms.
|
|
An investigation of material structure transformation in the cutting process
|
|
J. Peklenik (1), M. Kisin
|
|
STC C, 47/1/1998, P.83
|
|
Keywords: plastic deformation temperature, energy quanta, transformation of microstructures |
Abstract : An understanding of the cutting process and its mathematical modelling
requires knowledge about the material structures and their behaviours
under the mechanical and thermal loads in the transformation zone. The
tests with single and double phase microstructures - copper and carbon
steels, with preliminary deformed and undeformed structures have been
executed. The influence of various microstructures and process
conditions on the energy quanta and the plastic deformation temperature
in the transformation zone and the dislocation mechanism are better
understood. Preliminary accumulated energy in the material structure
contributed to the transformation energy and to a decrease of the
temperature. Based of these results some elements of the transfer
function of the process may contribute to a generic expression for an on
line cutting process identification.
|
STC Dn |
|
Engineering environments in the information age : research challenges and opportunities
|
|
F. Kimura (1), H. Lipson, M. Shpitalni (1)
|
|
STC Dn, 47/1/1998, P.87
|
|
Keywords: engineering environments, information technology, life cycle engineering |
Abstract : This paper examines changes to the contemporary product engineering
cycle resulting from the Information Age and identifies
information-related obstacles that correspond to the human dimension of
information overload in engineering. These obstacles may explain why
increases in productivity have been disappointing and why information
technology has not been able to satisfy the increasing demands placed on
contemporary engineers. Three productivity impeding categories are
discussed: (a) detail overload, (b) constraint overload, and (c)
versatility overload. The authors suggest how new emerging paradigms and
technologies can be harnessed to alleviate the identified difficulties.
Three directions for improvement are discussed: (a) bringing computer
tools into the engineering process earlier, permitting more extensive
exploration and informed selection of alternatives, (b) improving
human-computer interfaces towards in-context natural interaction, making
information exchange more fluent and fast, and (c) transforming
computers from passive to active self-initiated engineering aids that
can suggest alternatives and convey relevant information. The paper
discusses applications to areas such as design, manufacturing,
simulation, quality assurance, and maintenance.
|
|
3D scanning and level of detail modelling for design and manufacturing
|
|
A. Fischer (2), S. Park
|
|
STC Dn, 47/1/1998, P.91
|
|
Keywords: reverse engineering, scanning, progressive models |
Abstract : 3D scanning and modelling of manufacturing products play an important
role in the rapid prototyping cycle. In order to achieve accurate
reconstructed products, points are sampled at high density. However, for
reconstruction, conventional methods usually reduce the data
homogeneously without taking shape behavior, such as curvature and
topology, into consideration. As a result, essential characteristic
details may be lost. In this paper, an advanced method for
reconstructing progressive models is proposed. Through this method, the
reconstructed geometric model is represented by hierarchical levels of
detail. The option to explicitly control the levels of detail is
essential for design, modelling and analysis. The main advantage of the
approach is that the sampled points are significantly reduced to several
levels of abstraction, while at each level the geometric behaviour is
preserved. That is, even at lower resolution levels, critical details
are preserved. Moreover, the method has been extended to progressive
time and geometric models for simulation and is demonstrated by several
examples.
|
|
Automatic determination of 3-D parting lines and surfaces in plastic injection mould design
|
|
A.Y.C. Nee (1), M.W. Fu, J.Y.H. Fuh, K.S. Lee, Y.F. Zhang
|
|
STC Dn, 47/1/1998, P.95
|
|
Keywords: injection moulding, automated design, CAD |
Abstract : In this paper, a methodology to generate the 3-D parting lines and
parting surfaces is presented based on the optimal parting direction,
the geometrical characteristics and topological relationships of
injection moulded parts. The moulding surfaces are first classified into
three main groups according to their orientation to the parting
direction and their topological relationships. The largest edge-loop of
the surface group is then defined and the algorithm to generate the
edge-loop in different surface groups is proposed. The method to
calculate the projected area of an edge-loop on the plane perpendicular
to the optimal parting direction is also introduced. The 3-D parting
lines are generated based on the proposed criterion of considering the
above projected areas of edge-loops. After the parting lines are
determined, the parting surfaces are generated by extruding the parting
lines perpendicularly outwards to the parting direction. The case
studies show that the methodology is efficient in determining the
parting lines and the parting surfaces automatically in an intelligent
mould design system.
|
|
Integration of manufacturing processes in design
|
|
S. Tichkiewitch, M. Véron (1)
|
|
STC Dn, 47/1/1998, P.99
|
|
Keywords: design, integration, manufacturing |
Abstract : Constraints concerning the manufacturing of product parts must be
integrated as early as possible in the product design process, in order
to reduce costs and time to market. For this, a part of manufacturing
knowledge must be at the design team's disposal all through the design
process. In order to facilitate the consideration of machining and
forging capabilities by a group of designers, we have developed computer
tools. This paper describes the linkage of these tools with our CAD
system and the benefits of such integration in the form of shape and
cost evaluation.
|
|
Design by customers for mass customization products
|
|
M.M. Tseng (2), X. Du
|
|
STC Dn, 47/1/1998, P.103
|
|
Keywords: product design, requirement analysis, computer aided design |
Abstract : Producing what customers need with near mass production efficiency, or
Mass Customisation, has become a major trend in industry. Effective
definition of customer requirements is a pre-requisite for realizing
mass customisation. We propose "Design by Customers" as an approach for
companies to communicate to customers about what the company can offer,
to find out customer needs, to assist customers in making choices and to
negotiate for agreements. In this paper, the design and manufacturing
capabilities of a company are represented in a Product Family
Architecture. Adaptive Conjoint Analysis is then applied to help
customers assert their needs, define variations from base products,
visualize their options and assess alternatives.
|
|
An agent supported approach to collaborative design
|
|
Y. Jin, S.C.Y. Lu (2)
|
|
STC Dn, 47/1/1998, P.107
|
|
Keywords: design, coordination, system |
Abstract : Contemporary design problems are inherently complex and involve many
highly coupled sub-tasks that require multiple designers to work
together collaboratively. The designers' objectives are often in
conflict and activities inconsistent. How to provide effective
technology to support collaborative design has been a challenge for the
research community. This paper presents an agent-supported framework,
called ASCAD, for collaborative design. In ASCAD, a collaborative design
team is viewed as a collection of /design cells /and each design cell is
composed of a designer, a software agent, and a number of computer
tools. By monitoring designer's design activities, the agent in ASCAD
can help its designer coordinate with other designers through
identifying needs for coordination, establishing links between
designers, and providing suggestions for coordination decision-making. A
brief description and discussion of an initial demo application of ASCAD
is included to demonstrate the effectiveness of the ASCAD framework and
to illustrate future research directions.
|
|
Scheduling and coordination of distributed design projects
|
|
F. Liu, P.B. Luh, B. Moser / R.L. Kegg (1)
|
|
STC Dn, 47/1/1998, P.111
|
|
Keywords: scheduling optimization, distributed design project, coordination |
Abstract : In the era of time-based competition, companies are tending to
distribute product design across regions to cut short design cycles and
better penetrate local markets. This distributed design involves many
uncertainties and risks, and generating good decentralized schedules and
effectively coordinating distributed activities without intruding
organizations' propriety information and decision-making authorities are
important and challenging. This paper studies the scheduling and
coordination of distributed design projects with uncertainties while
managing design risks. A novel mathematical optimisation model that
balances modelling accuracy and computation complexity is presented, and
a solution methodology that combines Lagrangian relaxation and
stochastic dynamic programming is developed. Numerical results
demonstrate that near optimal solutions are obtained, and uncertainties
are effectively managed for problems of practical sizes.
|
|
Product design for disassembly and bulk recycling
|
|
M. Sodhi, W.A. Knight (2)
|
|
STC Dn, 47/1/1998, P.115
|
|
Keywords: design, disassembly, environmental |
Abstract : The recycling of manufactured products depends greatly on the efficiency
with which material can be separated from each other. For the long term,
recycling can be made more effective by the design of products for
greater use of disassembly and recycling. This requires the development
of suitable product analysis tools to enable design teams to evaluate
the ease of disassembly and recycling of alternative product concepts
during the early stages of design. This paper describes the development
of product analysis procedures for combined disassembly and bulk
recycling such that consequences of material selection upon the
end-of-life recovery of materials can be investigated.
|
|
Product quality evaluation based on behaviour simulation of used products
|
|
F. Kimura (1), T. Hata, H. Suzuki
|
|
STC Dn, 47/1/1998, P.119
|
|
Keywords: life cycle design, product quality evaluation, deterioration |
Abstract : For aiming at maintaining proper product functionality with reduced
disposal, a rapid product life cycle is proposed, which accelerates
product flow in product life cycle, and realizes early take-back of
obsolete products for reuse and upgrade. Commodity products, such as
household appliances and computer peripherals, are considered as target
products. As a basis for such life cycle design, a computer simulation
method is investigated for product quality evaluation under deteriorated
conditions. The proposed method has been tested for a functional
mechanism of a copying machine.
|
|
Product modelling for model-based maintenance
|
|
F.J.A.M. van Houten (1), T. Tomiyama, O.W. Salomons
|
|
STC Dn, 47/1/1998, P.123
|
|
Keywords: product, modelling, maintenance |
Abstract : The paper describes the fundamental concepts of maintenance and the role
that information technology can play in the support of maintenance
activities. Function-Behaviour-State modelling is used to describe
faults and deterioration of mechanisms in terms of user perception and
measurable quantities. Fault diagnosis, repair and maintenance
strategies are explained briefly. Model-based Maintenance is discussed
in terms of inspection, monitoring, diagnosis and planning, based on
functional, behavioural and state models. Some examples of mechanisms
illustrate the advantage of using computer-based models as a reference
for fault diagnosis. Underlying techniques like qualitative physics,
tolerance analysis, and dynamic simulation are discussed. The proposed
method is aiming at functionally robust designs, reduction of preventive
maintenance cost and more effective fault diagnosis.
|
|
Strategic planning of information technological infrastructures for life cycle management
|
|
F.-L. Krause (1), C. Kind
|
|
STC Dn, 47/1/1998, P.129
|
|
Keywords: information technology, life cycle, management |
Abstract : In parallel with the increase of the importance of life cycle management
aspects the appropriate supply of information according to specific
requirements within all life cycle phases becomes more important. By
this, an information management system is needed which has to be based
on an appropriate information technological infrastructure to secure the
information flows between life cycle phases distributed in place and
time. Within this contribution a reference model of such information
technological infrastructures will be presented, which contains the most
important elements to fulfil the complex tasks and can be used to derive
specific infrastructures. Based on this reference model a simulation
system is described which has the task to model and optimise information
technological infrastructures.
|
STC E |
|
Ways to intensify laser hardening technology
|
|
V.S. Kovalenko / D.F. Dauw (1)
|
|
STC E, 47/1/1998, P.133
|
|
Keywords: hardening laser, quality, improvement |
Abstract : At this stage of the laser material hardening development, few
techniques to intensify the process and to improve the quality of the
hardened surfaces may be proposed: 1) the development of new absorption
coatings to increase laser radiation absorption efficiency of the
surface to be hardened; 2) the development of devices to measure
material absorptivity and instant temperature in working zone at laser
irradiation to control treatment conditions; 3) the new compositions
development for alloying arid cladding; 4) the development of combined
techniques. The study results of these and other techniques are
presented and discussed.
|
|
Adaptive control for laser cutting using striation frequency analysis
|
|
H. Kaebernick (2), A. Jeromin, p. Mathew
|
|
STC E, 47/1/1998, P.137
|
|
Keywords: cutting, laser, adaptive control |
Abstract : An adaptive control system for laser cutting has been developed with the
aim to improve the productivity and the cut quality. The control
strategy is based on a set of parameters, which have an effect on the
quality of the cut, This paper focuses on one of these parameters,
namely the striations on the cut surface. A spectrum analysis technique
has been developed which allows striation frequency analysis to be used
on-line. It utilises a process monitoring system which detects light
emissions directly at the cut front. Cutting experiments with a 1.5kW
CO_2 laser using this technique have shown that it is possible to
improve the cut quality.
|
|
Excimer laser cutting : experimental characterisation and 3D numerical modelling for polyester resins
|
|
L.M. Galantucci / F. Giusti (1)
|
|
STC E, 47/1/1998, P.141
|
|
Keywords: excimer laser, cutting, modelling |
Abstract : Excimer laser has been proposed in these years as a new technology for
precision cutting of plastic materials, due to the photo ablative
mechanism and to the low thermal damage. Previous experiments, done by
the authors, on the cutting of kevlar reinforced composites with epoxy
matrix, using excimer laser, highlighted very high qualities not
attainable with other technologies. In the present work the attention
was focused on thermoset polyester resin, because of the extensive use
of this material as matrix for plastic composites.
The methodology proposed in this work allows to simulate in three
dimensions the laser cutting shape and size by means of a photo-ablation
approach, that takes also into account the thermal effects.
An experimental characterisation of the resin was performed to determine
the threshold fluence (energy surface density) and the other material
parameters needed to apply a photo-ablation model. The numerical
simulations, compared with the experimental cuts, gave results in good
accordance in terms of shape and depth of cut.
|
|
Micromachining with excimer laser
|
|
G. Ricciardi (2), M. Cantello (2), F. Mariotti, p. Castelli, p. Giacosa
|
|
STC E, 47/1/1998, P.145
|
|
Keywords: excimer laser, micro-machining, polymer |
Abstract : This paper deals with micromachining of different materials using a 100
W excimer laser at RTM laboratories. The first part of the works reports
the results of optical simulations carried out on several layouts
calculated using a sequential ray tracer in order to evaluate the
aberrations and improve the performance of the optics and masks.
Resolutions in the range of few micrometers have been achieved. The
second part of this paper deals with process testing on different base
materials such as metals, ceramics, polymers. The best results have been
achieved on polymers while metals show undesired effects of growth of
materials at the border of the processed area due to typically intense
shock waves. The reliability of polymer micromachining opens several
industrial fields of applications to the excimer laser technology. As an
example a drilling system for ink jet printer heads is briefly described.
|
|
An analysis of physico-chemical process of reactive ion etching (RIE) to adapt for three dimensional micro-machining
|
|
Y. Furukawa (1), A. Kakuta
|
|
STC E, 47/1/1998, P.149
|
|
Keywords: etching, micro-machining, single crystal silicon |
Abstract : Reactive Ion Etching (RIE) is more widely used in LSI production than
Plasma and Sputter etching for its inherent property as to act both
physically and chemically. The ratio of physical and chemical removing
reaction is not a concern so much in LSI production because of its role
to generate only surface features. However, some three dimensional micro
shapes could be generated by RIE if that ratio would be clarified. The
present study identified the RIE removing process model through a
variety of experiments by taking accounts both of physical reaction of
ions and chemical reaction of radicals to silicon, It became possible to
control an aspect ratio of micro-machined profiles by properly selecting
a condition of a Radio Frequency power and a reactor's pressure.
|
|
Removal characteristics of processing with SPM
|
|
T. Miyazaki, S. Yoshioka, Y. Shirai, T. Misu, N. Taniguchi (1)
|
|
STC E, 47/1/1998, P.153
|
|
Keywords: removal, processing, SPM |
Abstract : SPM (Scanning Probe Microscope) can be used as a processing tool. In the
present paper, process ings are carried out with AFM and STM in air at
room temperature. In case of AFM processing with silicon tips, no
depression is formed in gold workpiece; however, it is formed in silicon
workpiece, which seems to be caused by strong adhesion between the same
materials. In case of STM processing with tungsten tips, although
depressions are formed in the gold workpiece, the reproducibility is low
with hand-made tips; however, field evaporation processing is carried
out with high reproducibility.
|
|
An experimental investigation into the effect of hatch pattern in stereolithography
|
|
S.O. Onuh, K.K.B. Hon (2)
|
|
STC E, 47/1/1998, P.157
|
|
Keywords: stereolithography, rapid prototyping |
Abstract : The implementation of rapid prototyping technology in industrial and
domestic manufacturing processes has revolutionised new product
development process. The aim of this investigation is to study the
effects of layer thickness, hatch styles, hatch spacing, hatch overture
and hatch fill cure depth on specimens produced by stereolithography.
Previous investigations have shown that when layers are scanned in only
one direction, shrinkage forces occur mainly in the scanning direction.
Hence alternating the exposure of the layers will results in a more
homogeneous structure of residual stress in the part. A unique
experimental investigation has been carried out with a new hatch pattern
that has significantly improved the stereolithography product quality
adding a novel dimension to the technology.
|
|
Rapid prototyping by selective electrodeposition using electrolyte jet
|
|
M. Kunieda (2), R. Katoh, Y. Mori
|
|
STC E, 47/1/1998, P.161
|
|
Keywords: rapid prototyping, electro-deposition, micro-machining |
Abstract : This paper describes the development of a rapid prototyping technique
which can produce metal parts by electrodeposition using an electrolyte
jet. The calculated results verify that electrodeposition occurs
selectively at the spot where an electrolyte jet is impinged. To prevent
instability in electrodeposition, lapping was inserted regularly between
each deposition cycles, enabling walls to be formed without limiting the
height. Using copper nitrate aqueous solution as the electrolyte and a
round nozzle with a diameter of 0.53 mm, a copper micro-part was
fabricated successfully.
|
|
Minimization of machining allowance in electrochemical machining
|
|
K.P. Rajurkar (2), D. Zhu, B. Wei
|
|
STC E, 47/1/1998, P.165
|
|
Keywords: electro-chemical machining, environment, allowance |
Abstract : Electrochemical machining (ECM) provides one of the best alternatives
for producing complex shapes in advanced materials used in aircraft and
aerospace industries. However, the reduction of sludge and memory errors
continue to be major challenges for industries in addressing waste
generation and accuracy improvement. This study focuses on minimizing
the material to be removed by predicting minimum machining allowance and
improving the degree of localized dissolution. Experiments have been
conducted to verify the prediction results on an industrial ECM system.
The use of pulse current with passivating electrolyte has been found to
mitigate the sludge generation and improve accuracy.
|
|
Micro-EDM for three dimensional cavities - development of uniform wear method -
|
|
Z.Y. Yu, T. Masuzawa (1), M. Fujino
|
|
STC E, 47/1/1998, P.169
|
|
Keywords: EDM, Micromachining, microcavity |
Abstract : In this paper, we present a new method, called uniform wear method, for
3D micro-EDM. Simple electrodes such as with round or rectangular
section are used. Uniform wear at the end of the electrode was realized
by layer-by-layer machining. This maintains the original electrode shape
and converts the three dimensional electrode wear to a linear one. By
compensating the linear electrode wear, complicated three dimensional
cavities were successfully machined. This technique was developed for
micromolds, but the applicability for normal size molds was also confirmed.
|
|
System identification of wire electrical discharge machining
|
|
N. Mohri (2), H. Yamada, K. Furutani, T. Narikiyo, T. Magara
|
|
STC E, 47/1/1998, P.173
|
|
Keywords: wire EDM, vibration, identification |
Abstract : In wire electrical discharge machining (wire-EDM). it is very important
to restrain the vibration of the tool wire electrode for the improvement
of machining accuracy. In this paper, investigation is carried out
toward the dynamic wire vibration mechanism and a mathematical model is
derived. This model is compared with experimental results. The measured
displacement of a wire electrode in machining a thin plate is analysed
with impulsive force measured through impulse response by a single
discharge. The force acting on the wire depends on the direction of the
wire movement in vibration. A 3rd order system equation for the wire EDM
system is derived considering machining removal and vibrational features
of the system are discussed with the equation. As the discharge circuit
suddenly changes according to gap condition, this vibration system is
essentially nonlinear. Simulation of wire-EDM is performed with the
modelled system.
|
STC F |
|
On predicting the forming limit diagram for automotive aluminium sheet
|
|
S.G. Xu, K.J. Weinmann (1)
|
|
STC F, 47/1/1998, P.177
|
|
Keywords: forming limits, aluminium sheet, analysis |
Abstract : Aluminum has considerable potential as a material for automotive panels.
The ability to predict forming limit diagrams accurately for aluminum is
important for preventing failure in the forming process. A method is
proposed to develop forming limits using Hill's1993 yield criterion.
Predicted limit strains based on both Hill's 1948 and 1993 yield
criterion are compared with experimental data for Aluminum 6111-T4. It
is found that Hill's 1993 yield criterion can characterize localized
necking in aluminum sheets well, while Hill's 1948 criterion cannot.
The critical thickness rule is found useful in predicting the left hand
side of FLDs.
|
|
Enhancement of drawability by local heat treatment
|
|
F. Vollertsen, K. Lange (1)
|
|
STC F, 47/1/1998, P.181
|
|
Keywords: aluminium alloy, laser heat treatment, deep drawing |
Abstract : A method is described which can be used to increase the drawability of
aluminium alloys significantly. It is based on a local heat treatment of
the blanks, reducing the local flow stress by a restitution of the
precipitation particles. The term of homologous heat is introduced to
characterize the heat treatment parameters. Laser heat treated blanks
were deep drawn. The failure modes are discussed using an analytical
model for the drawing force of such blanks. It is shown that an increase
of the limiting drawing ratio from 2.1 for homogeneous blanks up to more
than 2.4 for inhomogeneous blanks can be reached.
|
|
Calculation of isothermal flow stress by combination of FEM and simple compression test
|
|
O. Kada, T. Miki, M. Toda, K. Osakada (1)
|
|
STC F, 47/1/1998, P.185
|
|
Keywords: forging, flow stress, finite element method |
Abstract : In forging processes, simulation by the FEM with temperature calculation
is frequently carried out to predict the forging load and others. For
the simulation, exact flow stress of the materials is essential but
almost no complete data of flow stress for temperature calculation are
available. This is because isothermal flow curve cannot be obtained
directly by simple compression test as the temperature in the specimen
is changed during deformation. The calculation method of isothermal flow
stress for the FEM with temperature calculation is proposed by removing
the effects of friction, heat generation, and heat transfer from the
results of simple compression tests.
|
|
An inverse approach for the design of the optimal preform shape in cold forging
|
|
R. Di Lorenzo, F. Micari (2)
|
|
STC F, 47/1/1998, P.189
|
|
Keywords: closed die forging, process design, statistical analysis |
Abstract : In closed die forging the preform design plays a critical role for the
success of the process: in fact it must ensure that in the finishing
step the desired product is obtained without shape defects such as
underfilling or folding and with a minimum material loss into the flash.
In the paper an inverse approach is applied to the preform shape
optimisation problem: the method permits to evaluate a response function
which links the set of parameters defining the preform shape with the
fulfilment of the product design specifications. The proposed approach
has been applied to a closed die forging process aimed to the production
of a C-shape component, and has allowed to determine the optimal preform
geometry which ensures the complete filling of the die cavity.
|
|
A new forging preform design approach using reverse simulation
|
|
C.C. Chang, A.N. Bramley (1)
|
|
STC F, 47/1/1998, P.193
|
|
Keywords: forging, upper bound, die design |
Abstract : A new reverse simulation approach for the optimal design of forging
preforms using the Tetrahedral Element Upper Bound Analysis (TEUBA) is
presented. The approach employs a criterion based on the concept of the
material distribution to determine the boundary condition and to
evaluate the complexity of the deformed shapes resulting from reverse
simulations. The approach aims to predict an initial billet section
which is close to a rectangle as ideal, or a preform shape where preform
stages are required. The produced preforms are assessed by performing
forward simulations with a commercial modelling package. The approach is
shown to have a considerable potential in preform design.
|
|
Controlled bending of aluminium extrusions
|
|
M. Geiger (1), A. Sprenger
|
|
STC F, 47/1/1998, P.197
|
|
Keywords: bending, aluminium extrusion, neural network control |
Abstract : This paper presents a control circuit for a stretch bending process of
aluminium extrusions. The control strategy is derived from an analytical
model which accounts for the process parameters allows the calculation
of springback. The first component of the control circuit is the
definition of suitable target and control values, for the later of
which tensile stresses have been qualified. Furthermore different
sources of information as for the characterisation of the workpiece are
discussed. The calculation of a new reference input variable is
executed by a neural network. Results as to the controlled bending
process will be given.
|
|
An integrated approach in design tooling, setting-up and timing of forging transfer-machines
|
|
P.F. Bariani (1), G. Berti, L. D'Angelo, J.J. Yang
|
|
STC F, 47/1/1998, P.203
|
|
Keywords: forging, tooling, press |
Abstract : Multi-station forging machines with automatic work transfer between
stations permit very high production rates to be reached, but
considerable time and effort by skilled personnel must be spent in
workplanning and their setting up and timing.
The paper presents an integrated approach to the computer-assisted
design of the tooling systems and identification of appropriate setting
conditions and timing for multi-station presses to be used in cold, warm
and hot forging.
The approach is based on (i) the classification of possible
configurations of punch- and die-side tool subassemblies, (ii) the
automatic retrieval of the tool-holder assembly configuration for the
specific station of the press, (iii) the assembly rules and automatic
scaling and fitting of individual tool components and (iv) the animation
-with check for interference- of die, punches, slugs, grippers and
ejectors according to the kinematic model of the press.
|
|
In-process punching with pressure fluids in sheet metal forming
|
|
E. Von Finckenstein (1), M. Kleiner, W. Homberg, E. Szücs
|
|
STC F, 47/1/1998, P.207
|
|
Keywords: punching with pressure fluids, process analysis |
Abstract : The economical efficiency of metal forming procedures based on pressure
fluids can be increased e. g. by integrating the additional (auxiliary)
operation of punching into the metal forming process. The potentialities
resulting from this proceeding are discussed exemplarily for a high
pressure sheet metal hydroforming process. The present investigation is
using the FE method for analysing and optimising various approaches to
in-process punching on high pressure sheet metal hydroforming.
Experimental tests are carried out in order to verify the different
approaches.
|
|
Modelling and control of hydroforming processes for flanges
|
|
J.C. Gelin (1), O. Ghouati, p. Paquier
|
|
STC F, 47/1/1998, P.213
|
|
Keywords: deep drawing, aquadraw, sensitivity |
Abstract : The modelling of hydroforming processes is studied from experiments and
numerical modelling using advanced finite element methods. The paper
demonstrates that simulation results fit well experiments. It also
demonstrates that is possible to access control of process driving
parameters, i.e. pressure in the die cavity or blank holder load in
order to achieve a specified result in term of shape or thickness
variation. The reliability and the accuracy of the proposed procedures
are illustrated in the case of flange forming for different geometries
and materials. It is demonstrated that the proposed method provides an
accurate tool to help the process designer to assess the effect of
process parameter on the final resulting sheet metal part.
|
|
Sheet metal forming of Titanium blanks using flexible media
|
|
N. Alberti (1), A. Forcellese, L. Fratini, F. Gabrielli
|
|
STC F, 47/1/1998, P.217
|
|
Keywords: sheet metal, titanium, FEM |
Abstract : Sheet metal forming processes using flexible media are increasingly
utilized in the industrial practice due to the relatively low tooling
cost. In the present investigation, a rubber forming process is applied
to the manufacturing cycle of a titanium alloy component for acoustic
tweeters. The proposed process allows a reduction in manufacturing costs
and production time since it permits the elimination of some joining
operations. The FEM analysis has permitted the definition of the optimal
process parameters and tooling geometry. Accordingly, several components
have been produced, the achieved quality level is comparable with the
one obtained utilizing the conventional technology and consistent with
the FEM predictions.
|
|
A study of mechanisms of liquid lubrication in metal forming
|
|
J. Bech, N. Bay (1), M. Eriksen
|
|
STC F, 47/1/1998, P.221
|
|
Keywords: liquid lubrication mechanisms, metal forming |
Abstract : Applying a transparent tool technique the lubrication in plane strip
drawing of aluminium sheet is studied providing the strip with surface
pockets for entrapment of lubricant. The compression and eventual escape
of trapped lubricant by Micro Plasto HydroDynamic Lubrication (MPHDL) as
well as Micro Plasto HydroStatic Lubrication (MPHSL) is observed and
quantified experimentally with varying lubricant viscosity, drawing
speed, reduction, die angle, back tension, workpiece material and
friction conditions. All these parameters are shown to influence the
mechanisms of lubricant escape in an explicable way. Theoretical models
for the two observed mechanisms of lubricant escape, i.e. backward
escape by MPHDL and forward escape by MPHSL are established combining a
continuum mechanic analysis of the pressure distribution in the
tool/workpiece interface with fluid mechanic analyses of the lubricant
escape. Experimental observations of oscillations in the drawing force
are quantitatively shown to be caused by the two mechanisms of lubricant
escape.
|
|
Mashy metal/alloy joining a new process for manufacturing new products
|
|
M. Kiuchi (1), J. Yanagimoto, S. Sugiyama
|
|
STC F, 47/1/1998, P.227
|
|
Keywords: forming, semi-solid, bonding |
Abstract : A new process to join metal and ceramics components on to aluminum,
copper and magnesium alloys was proposed. The process is based on
joinability of mashy (mushy/semi-solid) alloys. This paper shows the
obtained results regarding two types of joinings as follows. (1) Multi
wire fins (pins) were joined on to base blanks of an aluminum alloy.
(ex. Wire fin type heat- sinks were made.) (2) Multi sheet fins were
joined on to base blanks of an aluminum alloy (ex. Sheet fin type heat-
sinks were made.). The effects of process parameters on the shear
strength of interfaces between joined fins and base blanks and their
internal structures were investigated. Through the study, it is found
that the mashy- state joining makes it possible to join various
materials together which can not be joined by other processes such as
welding and soldering.
|
STC G |
|
Experimental investigation of methods to enhance stock removal for superfinishing
|
|
B. Varghese, S. Malkin (1)
|
|
STC G, 47/1/1998, P.231
|
|
Keywords: superfinishing, abrasion, loading |
Abstract : Superfinishing is widely used as a subsequent operation after grinding
to reduce surface roughness and increase bearing load capacity The
present investigation was undertaken to explore methods for enhancing
superfinishing performance. Experiments conducted on hardened bearing
steel indicate the existence of an optimal applied contact pressure
where both the stock removal and the finishing ratio are maximum and the
specific energy is minimum. Above the critical pressure, the stock
removal is adversely affected by loading of debris on the stone surface.
Applying ultrasonic vibrations normal to the surface was found to reduce
loading by promoting stone wear. Further enhancement in superfinishing
performance was achieved by providing axial grooves on the stone
surface. The use of ultrasonic vibrations together with axially grooved
stones increased the stock removal by as much as 65%37; while providing
comparable surface roughness.
|
|
Analysis on lapping and polishing pressure distribution
|
|
G.Q. Cai, Y.S. Lu, R. Cai, H.W. Zheng (1)
|
|
STC G, 47/1/1998, P.235
|
|
Keywords: lapping, polishing, pressure |
Abstract : In the processes of plane lapping and polishing, the pressure
distribution between the workpiece and the lapping plate or the
polishing pad is very important to flatness generation. This paper
presents elastic contact models for plane lapping and polishing with or
without guard ring. Based on these models. the pressure distribution has
been obtained. Furthermore, the effects of various parameters on the
pressure distribution, such as the material properties of the workpiece,
the plate and the pad, the ratio of load bearing on the guard ring to
the total load, the width of the guard ring, the gap between the
workpiece and the guard ring, and the thickness of the polishing pad,
have been discussed.
|
|
Rapidly renewable lap : theory and practice
|
|
C.J. Evans (2), R.E. Parks, D.J. Roderick, M.L. Mc Glauflin
|
|
STC G, 47/1/1998, P.239
|
|
Keywords: lapping, polishing, abrasion |
Abstract : The Rapidly Renewable Lap (RRL) uses a textured substrate over which
thin films are slumped. The substrate provides the geometry of the lap
and a localized texture, depending on the film thickness, properties,
and means by which it is deformed over and adhered to the substrate.
Abrasives, added to the film, lap or polish without touching or changing
the substrate geometry. Depending on process parameters, the RRL gives
brittle or ductile (two-body) lapping. This paper has two major themes:
it describes the RRL and some applications: and it shows that some
relatively simple lapping models predict of process characteristics.
|
|
Infeed grinding of silicon wafers applying electrophoretic deposition of ultrafine abrasives
|
|
Y. Tani (2), T. Saeki, Y. Samitsu, K. Kobayashi, Y. Sato
|
|
STC G, 47/1/1998, P.245
|
|
Keywords: surface grinding, mirror finish, silicon wafer |
Abstract : The application of electrophoretic deposition of ultrafine abrasives to
grinding cut-off of brittle materials has enabled both no chipping and a
mirror surface finish to be achieved using the developed aluminum-bonded
diamond cutoff wheels. Then we examined its application to infeed
grinding of silicon wafers to replace the lapping process. A series of
experiments clarified that desiccation due to electroosmosis caused
agglomeration of adhered abrasives onto the grinding wheel; and that
easy dropping-off of the agglomerates caused numerous scratches. Both
the increase of viscosity of grinding fluid by the addition of a
thickener and the decrease of applied voltage were performed to restrain
electroosmosis, which enabled a mirror surface finish of 23nmRt with no
scratches to be achieved.
|
|
Surface formation in creep feed grinding of advanced ceramics with and without ultrasonic assistance
|
|
E. Uhlmann / G. Spur (1)
|
|
STC G, 47/1/1998, P.249
|
|
Keywords: grinding, ceramics, surface formation |
Abstract : The process performance in grinding of advanced ceramics can be enhanced
by various kinematics of tool engagement. Based on the process
principles of creep feed grinding with and without ultrasonic
assistance, the surface formation of both methods is analysed using
analogy tests which simulate the engagement of single grains into the
surface. The ultrasonic superposition leads to altered mechanisms of
surface formation as well as wear behaviour of grains. SEM-pictures,
residual stress analyses and bending strength tests serve to evaluate
surfaces ground both with and without ultrasonic assistance. This
furnishes proof that ultrasonic assistance results in significantly
higher removal rates, but not in an additional damage of the sub-surface.
|
|
Generative precision grinding of optical glass
|
|
V. Sinhoff / W. König (1)
|
|
STC G, 47/1/1998, P.253
|
|
Keywords: grinding, glass, model |
Abstract : The deployment of cup wheels to precision-grind optical glass, offers
both considerable economic advantages and significant increases in
flexibility. In this contribution, the material removal mechanisms of
the grinding process will be analysed on the basis of material-specific
characteristics. Attention will focus on the transition phase from
brittle to ductile chip formation. The first step in which the process
model engages, is the identification of process-determining model
components. The material-specific machining characteristics are added to
the equation, permitting subsequent modelling of the interrelationships
which influence the process. By comparing the theoretical result with
the practical outcome, it is possible both to evaluate the model and to
determine which machining strategy is most suitable for the glass type
in question.
|
|
Computer-aided modelling of the fluting process for twist drill design and manufacture
|
|
E.J.A. Armarego (1), D. Kang
|
|
STC G, 47/1/1998, P.259
|
|
Keywords: twist drills, geometric modelling, CAD/CAM modules |
Abstract : Computer-aided models of a typical flute grinder, incorporating both
'forward' and 'backward' analyses, are outlined and used to simulate the
flute grinding process and study the intended or design flute profile of
twist drills. Based on recommended wheel profile and flute grinder
settings, the 'forward' analysis has shown that the generated lip flute
profile closely approximated the ideal profile for straight lip
production while the heel flute profile approximated a parabolic curve.
Furthermore the flute profile was partly generated by the 'envelope' of
the wheel profiles and partly by the locus of the point of discontinuity
on the wheel profile. The effects of the wheel profile and machine
settings on the generated flute profile have been studied. The
'backward' analysis, based on the 'contact curve' method, has shown that
only portions of the required wheel profiles to generate the given
'design' drill flute profiles were physically feasible so that the
generated flute profiles are only good approximations of the design
flute profiles. The use of these computer models in drill design and
manufacture are also discussed.
|
|
Kinematic simulation for analyzing and predicting high-performance grinding processes
|
|
G. Warnecke (2), U. Zitt
|
|
STC G, 47/1/1998, P.265
|
|
Keywords: grinding, modelling, simulation |
Abstract : In grinding technology, the application of superabrasives and increasing
demands for higher productivity and higher quality require an
appropriate selection of optimum set-up parameters. Therefore, the
development of analytical or empirical models for reliable prediction
of machining performance and work results is a key issue. This paper
presents a comprehensive concept for process modelling which provides a
software tool for analysing and designing high performance grinding
processes, using the method of kinematic simulation. On the basis of
synthetic 3D-models describing the macro- and micro-geometry of the
grinding wheel and the workpiece, together with mathematical models
describing the relative motions and kinematic engagement conditions,
grinding processes can be reproduced as the cumulation of multiple grit
engagements. The proposed simulation tool allows the generation of
optional grinding wheel topographies and the analysis and prediction of
the machining performance and work result for different grinding
techniques, taking into account thermo-mechanical and dynamic effects in
the contact area.
|
|
Development of resin -bonded diamond wheels with improved wear resistance using surface modified fine grains treated by radio-frequency magnetron sputtering
|
|
T. Semba, H. Fujiyama, H. Sato (1)
|
|
STC G, 47/1/1998, P.271
|
|
Keywords: diamond wheel, fine grain, surface modification |
Abstract : Experimental research for decreasing the wear of a resin-bonded diamond
wheel was conducted for the mirror grinding of dies and molds. The
gripping strength of diamond grains to the bond material was increased
by modifying grain surfaces with an SP_2 film using radio-frequency
sputtering. In addition, the adhesion strength in both the surfaces
between grain/S;02 film and S;02 film/bond material was increased using
the plasma activation technique and a silane coupling agent. The
grinding test revealed that the superficial area of diamond grains
increased conspicuously and chemical binding between grain surfaces and
bond material was generated, so that wear resistance superior to that
obtained using conventional nickel plated grains can be derived.
|
|
Validation of thermal properties in grinding
|
|
W.B. Rowe (1), M.N. Morgan, S.C.E. Black
|
|
STC G, 47/1/1998, P.275
|
|
Keywords: grinding, temperature, cbn |
Abstract : Thermal properties of the abrasive material are required for energy
partitioning and prediction of temperatures in grinding. Alumina and
cubic boron nitride wheels are investigated by several methods. A novel
sensor was designed to measure bulk thermal property. It is shown that
the effective thermal properties exhibited in the grinding process are
lower than the values measured directly. It is therefore concluded that
a grain model is more appropriate than a bulk property model. A case
study based on grinding AISI 52100 with cbn and alumina is used to
illustrate the sensitivity of the most significant parameters for fine
grinding.
|
|
Safe operations and friction characteristics of regulating wheel in centerless grinding
|
|
F. Hashimoto (2), G.D. Lahoti (2), M. Miyashita
|
|
STC G, 47/1/1998, P.281
|
|
Keywords: centerless, friction, safety |
Abstract : In the centerless grinding process, it happens on rare occasions that
the workpiece rotation suddenly speeds up toward the peripheral velocity
of the grinding wheel and, in the worst case, the workpiece jumps from
the grinding area. This phenomenon called "spinners" sometimes causes
the grinding wheel to burst. In this paper, the mechanism of spinner
occurrence is discussed. The existence of safeoperation zone, where
there is no risk of spinners, is presented with primary set-up
conditions. This paper also describes friction characteristics of the
regulating wheel that are the dominant factor in determining the
safe-operation zone. The test results of friction coefficients of
various regulating wheels are discussed, and the set-up guidelines to
avoid the spinner problem are proposed.
|
|
Forces in generating gear grinding-theoretical and experimental approach
|
|
B. Kruszynski, S. Midera / J. Kaczmarek (1)
|
|
STC G, 47/1/1998, P.287
|
|
Keywords: gear grinding, forces, model |
Abstract : Results of investigations carried out on the generating gear grinding
process, the so-called Niles method, are presented in the paper. A
detailed analysis of tooth profile generation shows that, due to the
complex kinematics, grinding conditions vary substantially during the
cycle of gear tooth creation which may, in turn, influence the grinding
forces. It was found that workspeed and dimensions of the layer being
removed in a particular generating stroke are the factors having the
greatest influence on the grinding forces. On the basis of extensive
analytical and experimental work the equations were proposed which allow
the calculation of the normal and tangential grinding forces in each
particular generating stroke of grinding wheel during tooth profile
generation. The analysis of maximum grinding forces in the tooth profile
grinding cycle as a function of process parameters is also presented in
the paper.
|
STC M |
|
Advantages of an open architecture structure for the design of predictive controllers for motor drives
|
|
D. Dumur (2), P. Boucher (2), J. Röder
|
|
STC M, 47/1/1998, P.291
|
|
Keywords: machine tool, CNC design, control |
Abstract : Due to the rapid innovation speed in the development of microprocessors
and communication technology, it becomes more and more necessary to
generate software in a hardware-independent /way. /The consequence of
this requirement is the introduction of a link between application
software and hardware, in an open architecture oriented structure. This
paper presents an open architecture structure of motor drives control
with a particular application to an induction machine axis control,
showing the connection between the motor (including load, PWM inverter,
current sensors, incremental encoders) and the software developments for
the end users (automatic design of the tuning parameters, design of the
controller) through a DSP based implementation of the real time part.
|
|
Open architecture modular tool kit for motion and machining process control
|
|
Y. Altintas (1), N.A. Erol
|
|
STC M, 47/1/1998, P.295
|
|
Keywords: CNC, machine tool, robot |
Abstract : An open and reconfigurable modular tool kit is presented for the design
of CNC systems for machine tools and machining process monitoring. By
selecting standard commands from the software tool kit library, the user
is able to design a new CNC system automatically. The developed system
allows integration of user developed program modules to the tool kit
library. The developed CNC is based on a fully integrated, open,
real-time, preemptive DSP operating system and a Windows NT application.
It has hardware independent architecture, and supports multiple DSP
boards and multiple host computers for machine tool and robot drive
motion control, trajectory generation and sensor based machining process
control and monitoring applications. The system can be quickly
configured to control different machine tools, robots and sensor based
processes by selecting standard script commands from the design library.
The paper contains sample applications for machine tool control and
sensor assisted machining applications.
|
|
Supervisory machining control : design approach and experiments
|
|
R.G. Landers, A. Galip Ulsoy (2)
|
|
STC M, 47/1/1998, P.301
|
|
Keywords: computer numerical control, machining module coordination, face milling |
Abstract : Monitoring and control of machining systems has been shown to
dramatically improve operation productivity and part quality; however,
very little attention has been given to the coordination of multiple
complex machining modules. The current practice is to design the module
coordination and to debug the resulting computer code in an /ad hoc
/manner. In this paper, the concept of supervisory machining control, in
the context of machining module regulation, is presented. The structure
of, and elements contained in, a supervisory controller are detailed,
and a systematic design procedure for constructing these controllers is
presented. The design procedure is utilized to construct a supervisory
machining controller which is experimentally implemented in a face
milling operation.
|
|
The effect of tool length on stable metal removal rate in high speed milling
|
|
S. Smith (2), W.R. Winfough, J. Halley
|
|
STC M, 47/1/1998, P.307
|
|
Keywords: metal removal rate, end milling, high speed machining |
Abstract : This paper describes the effect of the tool length on achievable stable
metal removal rate in high speed milling. Through finite element
computation and experiment, it is shown that the tool length most
strongly affects the natural frequency of the most flexible mode. The
change in frequency changes the most stable speed in the stability lobe
diagram. The highest metal removal rates occur when the tool length is
selected to match the stable zone to the highest spindle speed.
Sometimes longer tools can provide higher metal removal rates than
shorter tools because they utilize the stability lobe phenomenon more
effectively.
|
|
Linear magnetic bearing and levitation system for machine tools
|
|
M. Weck (1), U. Wahner
|
|
STC M, 47/1/1998, P.311
|
|
Keywords: linear magnetic bearing, linear direct drive, high-speed machining tool |
Abstract : Magnetic bearings work without abrasion, (static) friction and attrition
while providing the highest possible travel velocity and acceleration.
Consequently magnetic bearings could be ideal guideways for high-speed
machine tools. This paper describes a new linear magnetic bearing system
suitable for machine tools. Within this contribution the development of
a test bench with a linear synchronous direct drive and a magnetic
bearing and levitation system is presented. The conjunction of
electrical, electronic and mechanical components as parts of a
mechatronical system is shown. In addition, measurements of the
stiffness are presented to demonstrate the feasibility of the approach.
|
|
Analysis of thermal deformation of an ultraprecision air spindle system
|
|
T. Moriwaki (1), E. Shamoto
|
|
STC M, 47/1/1998, P.315
|
|
Keywords: thermal deformation, ultraprecision air spindle, transfer function |
Abstract : Thermal behavior of the main air spindle system of an ultraprecision
machine tool is analyzed experimentally. Influences of the heat
generated due to the spindle rotation and the temperature variation of
the ambient air are considered. It is found that the thermal deformation
due to the ambient temperature change increases with an increase in the
rotational speed, which is considered to be caused by an increase in the
heat transfer. The transfer functions between the rotational speed of
spindle and the thermal deformation and between the ambient temperature
and the thermal deformation are obtained separately. A simple method to
estimate and compensate the thermal deformation is proposed by utilizing
the measured transfer functions and the convolution integral, and
machining errors due to the above two heat sources are successfully
reduced to less than 15%37;.
|
|
Balancing requirements for fast rotating tools and spindle systems
|
|
H. Schulz (1), T. Würz
|
|
STC M, 47/1/1998, P.321
|
|
Keywords: balancing, high-speed machining, vibration |
Abstract : Technical standards as they are defined in ISO 1940 are more and more
insufficient for high-speed tools and spindle systems in order to
guarantee a stable machining process. This paper shows the
system-specific limitations of the component focused balancing. The
effects of the unbalanced tool onto the machining process as well as the
machine's behaviour can be used as system focused criteria in order to
evaluate the required balancing status. These will be discussed by means
of analytical and numerical approaches and are verified by experimental
results. The new aspect to set the balancing requirements by vibrational
loads of the spindle bearings is confirmed by simulation models.
|
|
Robust control of feed drives with linear motors
|
|
H. Van Brussel (1), P. Van Den Braembussche
|
|
STC M, 47/1/1998, P.325
|
|
Keywords: machine tool, control |
Abstract : Linear motors experience a real breakthrough for machine tool
applications. Besides their outspoken advantages, they have the
important drawback that load variations are directly felt by the motor.
Robust controllers are needed to cope with these problems. This paper
presents results obtained with two robust control schemes, one based on
H synthesis and the other on sliding mode control. Excellent robust
performance has been obtained, like e.g. load changes up to 300^0 1/.
can be dealt with and have only a negligible influence on the tracking
error.
|
|
Form-shaping system of machine tools : theory and applications
|
|
V. Portman, I. Inasaki (1), M. Sakakura, M. Iwatate
|
|
STC M, 47/1/1998, P.329
|
|
Keywords: machine tool, form generation, accuracy |
Abstract : The form-shaping process is the main functional process performed by a
machine tool. A theory of the form-shaping system (FSS) investigates
interrelationships between, on the one hand, geometry and kinematics of
the machine tool and, on the other, geometry and accuracy of the
machined part. In this paper, the FSS theory is developed in the
following ways: (1) the general approach spreads also to the FSS with
parallel-type links (previously, only chaintype systems were
discussed); (2) direct and inverse form-shaping problems are formulated.
|
|
Modular synthesis of machine tools
|
|
M. Zatarain, E. Lejardi, F. Egana / R. Bueno (1)
|
|
STC M, 47/1/1998, P.333
|
|
Keywords: machine, module, dynamics |
Abstract : In the current state of the art, calculation of static and dynamic
behaviour of machine tools requires the modelling of the complete
structure and components by the Finite Element Method. If calculation at
several machine positions is required, major adaptations of the FEM
model are needed.
The article shows a method
by means of which "precalculated structures" can be used to obtain the
complete model of the machine at any position of its axis in a very
straightforward way. Besides being a helpful tool for the analysis of a
particular machine, the method permits the organisation of a database in
which general-purpose modules can be introduced for the calculation of
the complete machine in a very short time.
The whole method and database have been programmed, and results obtained
correlate very closely with the ones obtained by the classical FEM.
|
|
Development of hexapod based machine tool
|
|
H.J. Warnecke (1), R. Neugebauer, F. Wieland
|
|
STC M, 47/1/1998, P.337
|
|
Keywords: machine, hexapod, milling |
Abstract : Machine tools with parallel structures have been the subject of
discussion for a while now. Users are still largely unaware of the
advantages offered by these new machine structures. This paper describes
the design and variants of parallel-structured machine tools. Different
design variants are compared with regard to the load of the structures
and the singularity. Starting out from the requirements of die and mold
making, this paper presents the development of an hexapod machine tool
prototype. The paper is finishing with a processing simulation and a
outlook for further investigations.
|
|
An integrated methodology for the design of parallel kinematics machines (PKMs)
|
|
L. Molinari-Tosatti, G. Bianchi, I. Fassi, C.R. Boer (2), F. Jovane (1)
|
|
STC M, 47/1/1998, P.341
|
|
Keywords: parallel kinematics machine, hexapod, virtual design |
Abstract : The paper describes an approach to Parallel Kinematics Machines design
integrating tools for machine configuration, synthesis and analysis. An
example is shown for a 6 d.o.f. hexapod prototype developed at ITIA-CNR.
|
|
The local dexterity, optimal architecture and design criteria of parallel machine tools
|
|
T. Huang, D.J. Whitehouse (1), J. Wang
|
|
STC M, 47/1/1998, P.347
|
|
Keywords: parallel machine tools, dexterity, optimum design |
Abstract : In this paper, the analytical expressions of the local dexterity loci of
parallel machine tools described by the singular values of the Jacobian
matrix are formulated. It has been proved that the different kinematic
performance indexes to evaluate the dexterity of the machine tools are
inherently identical. The parametric relationship to obtain isotropy
configurations is derived. By introducing the concept of relative
dexterity, the design criteria in conjunction with the detailed
procedure are proposed according to the specific requirements. It has
been concluded via examples that if the dimensional parameters are
designed in such a way that the local kinematic performance is
satisfactory, so is the global performance provided that the reachable
orientation of the mobile platform is limited due to the constraints of
the passive joints and actuated variables.
|
STC O |
|
Product life cycle costing applied to manufacturing systems
|
|
E. Westkämper (1), D.v.d. Osten-Sacken
|
|
STC O, 47/1/1998, P.353
|
|
Keywords: decision making, product, cost |
Abstract : Life Cycle Costing (LCC) supports the adaptation of product features,
both consumer and capital goods; to their life cycle. The costs of
production, installation. usage and disposal are analysed and allocated,
aiming at the minimum of the total cost. A new method to calculate the
life cycle costs of capital goods, such as machines and manufacturing
systems, is presented to anticipate the life cycle costs. Single
processes connected to the product's life cycle are represented and
described in a potential-, program- and process- related way by the
above mentioned life cycle costing method. Aiming on a redesign of
current product structures, it is possible to derive approaches from the
cost structures of the life cycle and also to create possibly new
operational and maintenance concepts, as well as new financing models
and cooperation forms.
|
|
Design-to-cost for production systems
|
|
W. Eversheim (1), J. Neuhausen, M. Sesterhenn
|
|
STC O, 47/1/1998, P.357
|
|
Keywords: cost modelling, system design, production system |
Abstract : The objective of cost modelling is to evaluate the costs of a product
and how these costs are likely to alter with changes to the system
design, product components and processes. Specifically, this includes
the breaking down and ranking of cost into its core elements. While
manufacturing costs are essential to product system evaluation,
performance subsequent to customer requirements needs also to be
considered. Design-to-Cost for Production Systems presents a generic
methodology to combine cost modelling and Quality Function Deployment in
order to assess the potential trade-off between cost and performance for
competing product alternatives at the early stage of the production
system design process.
|
|
Product line development with customer interaction
|
|
A. Markus (2), J. Vancza
|
|
STC O, 47/1/1998, P.361
|
|
Keywords: optimization, product development, production management |
Abstract : While customizing their products, manufacturers attempt to fulfill
specific requirements of the customers within the constraints dictated
by the manufacturing (design, planning and production) environment, and
by the economical necessity of earning profit. This paper offers a
generic framework that captures more technical features of this problem
than the marketing models: in addition to customer welfare and profit
maximization considerations, engineering aspects are made operational,
too. Driven by the interaction between customer preferences and the
reallocation of manufacturing resources, viable product families emerge
from a variety of technically feasible product alternatives.
|
|
Approaches to managing changes and uncertainties in manufacturing
|
|
L. Monostori (2), J. Hornyak, B. Kadar
|
|
STC O, 47/1/1998, P.365
|
|
Keywords: holonic manufacturing systems, dynamic scheduling, artificial intelligence |
Abstract : Today's complex manufacturing systems operate in a changing environment
rife with uncertainty. The performance of manufacturing companies
ultimately hinges on their ability to rapidly adapt their production to
current internal and external circumstances. Two main kinds of
approaches to dealing with the enumerated problems are: to enhance the
reactivity of traditionally structured (mostly hierarchical) systems by
sophisticated new control techniques, and to construct decentralised,
distributed systems. Along both of these - overlapping - lines, the
authors developed a genetic algorithm (GA) based dynamic scheduler [4]
and a distributed, agent-based shop floor control system to be
introduced here which relies on the holonic concept. The approaches are
realised by using an object-oriented framework for developing and
testing new control architectures and algorithms in the manufacturing
domain. Finally, the co-operative use of agentbased distributed control
structures and the more centralised (GA-based) scheduler is proposed
aiming at systems which can handle critical complexity, reactivity,
disturbance and optimality issues at the same time.
|
|
Impact of manufacturing system configuration on performance
|
|
Y. Koren (1), S.J. Hu, T.W. Weber
|
|
STC O, 47/1/1998, P.369
|
|
Keywords: system, quality, productivity |
Abstract : Manufacturing systems can be designed in many configurations. Different
configurations have profound impact on the performance of the system in
terms of reliability and productivity, product quality, capacity
scalability, and cost. This paper analyses these performance measures
for different system configurations assuming known machine level
reliability and process capability.
|
|
A method for performance evaluation of automated flow lines
|
|
T. Tolio, A. Matta / F. Jovane (1)
|
|
STC O, 47/1/1998, P.373
|
|
Keywords: automated assembling, system modelling, performance evaluation |
Abstract : In order to find the optimal configuration of an automated flow line it
is necessary to compare the performance of several alternative
configurations. In this situation the use of simulation is normally not
viable given the high modelling and computational effort it would
require; on the other hand, the application of classical analytical
tools would often entail the adoption of unrealistic assumptions. To
solve this problem, the paper presents an approximate analytical method
that overcomes many of the limitations of analytical tools while
preserving good accuracy and low computational effort. In particular the
method can deal with deterministic processing times, finite buffer
capacity and multiple failure modes of the machines. This last feature
represents an important improvement over existing techniques and is very
useful when dealing with automated assembly lines where each station is
composed by different devices that have different reliability and
different ways to get repaired. The validation of the method has been
carried out by means of extensive testing and comparison with
simulation. An application to a real case is also reported.
|
|
New concepts and methods for developing shop floor control systems
|
|
H.J. Lynggaard, A. Bilberg, L. Alting (1)
|
|
STC O, 47/1/1998, P.377
|
|
Keywords: shop floor, control systems, cell control |
Abstract : An industrial research project defines models and methods for design and
implementation of computer based control and monitoring systems for
production cells. This is primarily documented within automated robot
welding cells in the shipbuilding industry. In order to support
engineering of cell control systems by the use of enablers, a generic
cell control data model and an architecture has been defined. Further an
engineering methodology is defined. It is concluded that cell control
technology provides for increased performance in production systems, and
that the cell control engineering concept reduces the effort for
providing and operating high quality and high functionality cell control
solutions for the industry. The plans for the next generation industrial
shop floor and cell controllers are to develop new concepts based on
more distributed systems, which are more robust and agile with respect
to changing demands, technological advances and daily operations. The
scope of these systems are a network of co-operating cells as opposed to
individually operated cells which are co-ordinated in a traditionally
(hierarchical planning) manner. This new approach raises new demands for
the individual cell as well as its ability to cooperate.
|
|
Development of upgradable cellular machines for environmentally conscious products
|
|
S. Kondoh, Y. Umeda, H. Yoshikawa (1)
|
|
STC O, 47/1/1998, P.381
|
|
Keywords: cellular, manufacturing, environment |
Abstract : To reduce material and energy consumption and amount of disposal,
prolongment of product's lifetime is quite promising. Such longer-life
products should have functional upgradability besides reliability and
fault-tolerance, because most customers buy a new product when the old
one is functionally out-of-date. For this purpose, this paper proposes
the upgradable cellular machine. A cellular machine is a flexible
modular machine that consists of autonomous and intelligent units
(called "cells"). This paper demonstrates the upgradability of the
cellular machine by illustrating the development of an experimental
cellular assembly system based on the cellular automatic warehouse which
the authors' group has already developed.
|
|
Competence requirements and their impact on manufacturing system performance
|
|
A. Kinnander, T. Ilar, U. Eriksson / G. Sohlenius (1)
|
|
STC O, 47/1/1998, P.385
|
|
Keywords: manufacturing, simulation, performance, evaluation |
Abstract : Research into "Next generation manufacturing systems" stresses the use
of semi-automated systems to handle short product life cycles and
customer oriented production. Despite increasing dependency on
technology, the importance of humans is expected to increase and to
provide a realistic basis for decision support, both technical and
organisational processes must be included in simulation models. In a
rapidly changing environment, skill development is also important and
should be considered when developing simulation models.
This paper describes two case studies where competence and skill
development were modelled using learning curves to obtain a more
representative simulation of system performance.
|
|
Interactive manufacturing : human aspects for biological manufacturing systems
|
|
K. Ueda (2), J. Vaario, N. Fujii
|
|
STC O, 47/1/1998, P.389
|
|
Keywords: manufacturing systems, interactive system, human |
Abstract : Interactive manufacturing is a new idea to cope with the difficulties
caused by growing complexity of manufacturing activities. By interaction
among humans such as designers, manufactures and consumers, and
artifacts throughout artifact life-cycle each participant would
iteratively improve. After classifying the problem difficulties in terms
of incompleteness of the environment description and system
specification, this study focuses on human interaction in production
domain based on Biological Manufacturing Systems. This paper shows how
the virtual space combined
with self-organization enables the human participation, and discusses
the effectiveness of interactive manufacturing to solve the
difficulties, by demonstrating an example using industry data.
|
|
Practical aspects of CALS in design and manufacturing of sheet metal products
|
|
M. Shpitalni (1), L. Alting (1), A. Bilberg
|
|
STC O, 47/1/1998, P.393
|
|
Keywords: optimization, sheet metal manufacturing, information technology |
Abstract : The transition from design to process planning and to the various stages
of manufacturing is traditionally sequential. In many cases, practical
problems associated with manufacturing cannot be resolved if only
individual processes are examined. These problems can be overcome,
however, by adopting the CALS approach. This approach requires global
observation and allows actual and current information to flow both
forward and backward. This information, regardless of the specific
process in which it has been generated, is used to improve the entire
global process. This paper is concerned with the design and manufacture
of sheet metal parts. It is demonstrated that through implementation of
the CALS approach, the overall process can be optimised and products can
be manufactured significantly more accurately, faster and less expensively.
|
|
Life cycle simulation applied to a robot manipulator - an example of aging simulation of manufacturing facilities -
|
|
S. Takata (2), A. Yamada, T. Kohda, H. Asama
|
|
STC O, 47/1/1998, P.397
|
|
Keywords: life cycle management, deterioration evaluation, robot manipulator |
Abstract : Evaluation of the aging process of manufacturing facilities is essential
for life cycle facility management, which includes such activities as
design for reliability and maintainability and maintenance planning. For
this purpose, we have developed a life cycle simulation system for robot
manipulators. The developed system car simulate the wear of gears and
bearings of joints as component deterioration and evaluate the resultant
positioning error of an end-effector as functional degradation. The
system is applied to assembly robots of a car parts manufacturing plant.
The simulation results correspond to the failure history of the robots
fairly well.
|
|
On-line simulation and control in manufacturing systems
|
|
H.A. ElMaraghy (1), I.B. Abdallah, W.H. ElMaraghy
|
|
STC O, 47/1/1998, P.401
|
|
Keywords: simulation, scheduling, flexible manufacturing system (FMS) |
Abstract : In this paper a novel on-line simulation framework for multi-resource
(i.e., machines-workers-auxiliary resources) constrained Flexible
Manufacturing Systems (FMSs) is presented. This framework is based on
combined optimisation and simulation techniques. Optimisation procedures
are used for initial off-line scheduling and on-line rescheduling (in
case of disturbance), using Petri nets, genetic algorithms and
dispatching rules. Various performance measures such as minimizing the
makespan and the mean flow time were considered. This framework is
implemented using Arena, Microsoft Access, and Microsoft Visual C/C++.
Random events are introduced on-line using a user interface provided by
Arena Real-time template. The proposed framework will be implemented for
the control of an industrial flexible printed circuit board assembly system.
|
|
A fuzzy discrete event simulator for fuzzy production environment analysis
|
|
G. Perrone, S. Noto La Diega (1), A. Zinno
|
|
STC O, 47/1/1998, P.405
|
|
Keywords: fuzzy, production systems, simulation |
Abstract : Discrete Event Simulation is a powerful tool to help production managers
in planning manufacturing systems. The necessity to rapid react to
market conditions is pushing production planners to process requirements
and information affected by vagueness. Vagueness is related with event
definition, therefore it is not manageable through statistical tools,
but more properly by using fuzzy mathematics. Production situations
where uncertainty takes body in term of vagueness are referred as /Fuzzy
//Production //Environments /Classical Discrete Event simulators are not
suitable to deal with fuzzy variables, therefore they cannot be used to
model Fuzzy Production Environments. This paper aims to fill this gap in
the production research exploring a very untouched area within this
framework, that is the development of a proper tool for Fuzzy Discrete
Event Simulation.
|
|
Environmental-based systems planning for machining
|
|
P. Sheng, D. Bennett, S. Thurwachter / B.F. von Turkovich (1)
|
|
STC O, 47/1/1998, P.409
|
|
Keywords: machining, environment, planning |
Abstract : An approach for incorporating multi-endpoint environmental effects in
manufacturing systems planning is presented. This approach combines unit
process models, hazard evaluation and systems simulation to develop a
predictive capability for energy consumption, waste flows and exposure
risks over a planning horizon. Case studies for a machining transfer
line are presented to show a hierarchy of decisions supported using this
method, including effects of production rate constraints, catalyst
selection and resource allocation.
|
|
Dynamics of real-time distributed scheduling in multiple- machine heterarchical manufacturing systems
|
|
N.A. Duffie (2), P.O. Kaltjob
|
|
STC O, 47/1/1998, P.415
|
|
Keywords: manufacturing, system, control |
Abstract : Heterarchical manufacturing systems with highly-distributed, real-time
control of arrival times of parts exhibit high levels of robustness and
adaptability to changes in machine availability, part mix, processing
times, and due dates. However, distribution of control and queuing in
these systems makes analysis and modelling difficult, particularly when
parts proceed through multiple processing steps and these processing
steps can be performed by more than one machine.
In this paper, a general approach is presented for modelling these
systems. Examples of multiple-machine and multiple-processing-step
systems are presented, illustrating their behaviour and closed-form
solutions obtained of discontinuous differential equations that
represent their dynamics.
|
|
An integrated process planning and scheduling system for block assembly in shipbuilding
|
|
K.K. Cho (1), J.S. Oh, K.R. Ryu, H.R. Choi
|
|
STC O, 47/1/1998, P.419
|
|
Keywords: assembling, process planning, scheduling |
Abstract : This paper describes an integrated process planning and scheduling
system for block assembly in shipbuilding. The system consists of
process planning module, scheduling module, bottleneck block selection
module, and process re-planning module. A rule-based reasoning
technology is applied to determine optimal assembly units and assembly
sequences in generating initial process plans. For scheduling module, a
schedule revision heuristic is developed for efficient reallocation of
blocks to alternative assembly shops. For bottleneck block selection
which plays a central role in bridging process planning and scheduling,
a powerful heuristic is developed by employing an entropy-based
partitioning method for identifying bottleneck periods. The experimental
results with data from a real shipyard show that our search heuristics
are very effective and efficient.
|
|
LP-based heuristics for the capacitated lot sizing problem
|
|
P. Brandimarte, A. Alfieri / R. Levi (1)
|
|
STC O, 47/1/1998, P.423
|
|
Keywords: production planning, optimization, material requirements planning (MRP) |
Abstract : Master Production Scheduling is a cornerstone of MRP II systems, since
it represents the link between marketing and production. To overcome the
limitations of MRP II systems, we aim at finding a good and realistic
MPS by optimisation techniques, rather than by a trial-and-error manual
procedure. Due to the complexity of the resulting mathematical model,
heuristic solution strategies must be devised. In this paper we report
computational experiments on the application of approximate solution
methods, based on Linear Programming, to a simplified version of the
problem, namely the Capacitated Lot-Sizing Problem (CLSP). We show the
usefulness of suitable model reformulations and of interior point
solution methods.
|
|
A petri net technique for process planning cost estimation
|
|
P. Xirouchakis, D. Kiritsis, J.-G. Persson (2)
|
|
STC O, 47/1/1998, P.427
|
|
Keywords: CAPP, cost, petrinet |
Abstract : The problem under consideration is the cost estimation of operation
sequencing for non-linear process planning, i.e. taking into account
processing alternatives in order to determine overall costs for feasible
process plans we take into account in our Petri net model costs caused
by machine, setup and tool changing in addition to the single operation
cost. We introduce a new Petri net model that allows the application of
cost analysis algorithms. This is a PP-net (Process Planning net) which
represents manufacturing knowledge in the form of precedence constraints
and incorporates machining cost, machine, setup and tool information in
each transition. We show that the PP-net allows the calculation of the
optimum process plan without the need to first develop all possible
solutions. We apply the developed methods and calculate the optimum
process plan to an industrial case study of a mechanical workpiece of
moderate complexity.
|
|
A systems approach for modelling mechatronics systems
|
|
B.A. Hussein / O. Bjoerke (1)
|
|
STC O, 47/1/1998, P.431
|
|
Keywords: mechatronics, system, modelling |
Abstract : This paper presents a unified approach based on utilizing
multidimensional arrays in order to model the physical and logical
properties of mechatronics systems. A mechatronics system model consists
of two interacting submodels. A submodel that describes aspects related
to energy flow in the physical system, and another submodel that
describes aspects related to information flow in the control system. The
multidimensional array based approach of modelling provides us with the
possibility to use one terminology and the same formalism for modelling
both subsystems. The consequence of using the same formalism is that
simulation of the mechatronics system can be performed using only /one
/simulation environment.
|
|
Coordinative generation of machining and fixturing plans by a modularized problem solver
|
|
K. Teramoto, M. Onosato, K. Iwata (1)
|
|
STC O, 47/1/1998, P.437
|
|
Keywords: end milling, fixture, planning |
Abstract : In the conventional end-milling research, fixturing and machining plans
in operation planning are generated separately, although those
generations are mutually dependent. Advanced machining operations are
directed to complicated and/or thin shape workpiece precision machining.
This trend requires to consider the interdependency between machining
and fixturing. This interdependency is dealt with in the newly developed
coordination cycle where physical consistency and evaluation coherence
are managed. This research paper presents a basic framework and
procedure of the problem solving for coordinative generation of
machining and fixturing plans. This paper also describes an example to
demonstrate the effectiveness of the method.
|
|
Simulation of NC machining with cutter deflection by modelling deformed swept volumes
|
|
M.C. Leu (2), F. Lu, D. Blackmore
|
|
STC O, 47/1/1998, P.441
|
|
Keywords: numerical control (NC), machining, simulation |
Abstract : Most research on the representation of swept volumes has been limited to
motion of rigid objects. In this study, a Sweep Differential Equation
(SDE) approach is presented for the representation of deformed swept
volumes associated with flexible objects. The deformed swept volume
analysis is integrated with machining mechanics to account for cutter
deflection in NC simulation. End milling is modelled and analysed and
the cutter deflections are computed and integrated with an SDE based
software program which is developed in C++ for the generation of
deformed swept volumes. It is shown that this approach constitutes an
effective NC simulation technique with capabilities for geometric
verification and machining tolerance checking.
|
STC P |
|
Design of a high-precision 3D-Coordinate Measuring Machine
|
|
M.M.P.A. Vermeulen, P.C.J.N. Rosielle, P.H.J. Schellekens (2)
|
|
STC P, 47/1/1998, P.447
|
|
Keywords: coordinate measuring machine, high-precision design |
Abstract : In Precision Engineering components are getting smaller and tolerances
become tighter, so demands for accuracy are increasing. To improve the
precision of Coordinate Measuring Machines (CMMs) we designed an
alternative high precision 3D-CMM with measuring uncertainty beneath 0.1
µm in a measuring volume of 1 dm'. The machine design is based on the
Abbe and Bryan principle, thus smaller measuring errors are feasible
with less effort on software compensation. Application of a light and
stiff construction, compensated air bearings and well-positioned linear
motors result in high stiffness and favourable dynamic behaviour. A
statically determined design, extensive use of aluminium and mechanical
thermal length compensation make the machine less sensitive to
temperature changes. To prevent mechanical disturbances an active
vibration isolation system was designed. This paper focuses on machine
design aspects showing analytical- and experimental results and design
synthesis.
|
|
The influence of measurement strategy on the uncertainty of CMM- measurements
|
|
A. Weckenmann, M. Knauer / H. Kunzmann (1)
|
|
STC P, 47/1/1998, P.451
|
|
Keywords: coordinate measuring machine (CMM), uncertainty |
Abstract : The accuracy of the results from coordinate measurements depends on the
accuracy of the measuring device, workpiece properties, environmental
conditions, and especially operator procedures. For the last, and
usually most important factor, neither are proven facts known about the
combined effects of the various influences nor do any general
quantitative statements exist.
A proposal is made for structuring the area "operator influence" with
special focus on measuring strategy with the components sampling
strategy (number and distribution of sampled points), evaluation
criteria, and filters, Design and function of a software system to
simulate measurements of workpieces with typical deviations are described.
|
|
Autonomous coordinate measurement planning with work-in-progress measurement for TRUE-CNC
|
|
H. Ng, J. Liu, K. Yamazaki (2), K. Nakanishi, K. Tezuka, S.K. Lee
|
|
STC P, 47/1/1998, P.455
|
|
Keywords: CMM part programming, dimensional inspection, in-process measurement |
Abstract : The paper deals with the autonomous programming technology for the high
speed coordinate measuring machine (CMM). In order to provide the
breakthrough technology to enhance the operability of CMMs to be used
for in-line measurement of mechanical parts, a new autonomous
programming method which automatically generates a CMM program from the
CNC program used for machining of the part is proposed. The developed
technology can provide new functionality such as efficient
work-in-progress measurement capability without using the CAD product
model based approach.
|
|
In-process measurement method for detection and discrimination of silicon wafer surface defects by laser scattered defect pattern
|
|
S. Takahashi, T. Miyoshi, Y. Takaya, K. Saito (2)
|
|
STC P, 47/1/1998, P.459
|
|
Keywords: optical measurement, surface defect, ultra-precision |
Abstract : A new optical measurement method for evaluating the defects on a silicon
wafer surface quantitatively, which will be able to be applied to
in-process measurement, is presented. The experimental system for
measuring the defects consists of the Fourier transform optical system
using of a high-power objective. In order to verify the feasibility of
application of this method to in-process measurement, scanning
experiments for small particles, which are typical defects on the
silicon wafer surface, are carried out. It is shown that the proposed
method is effective for detecting and discriminating the small defects
with the size of sub micrometer order.
|
|
On the gap between design and implementation of MEMS
|
|
D. Seter, M. Hershkovitz, S. Kaldor (1)
|
|
STC P, 47/1/1998, P.463
|
|
Keywords: precision, micro-machining, silicon |
Abstract : The paper discusses implementation problems, adopted during development
and fabrication, of Silicon micro-sensors. For example, the paper refers
to a micro rate sensor (Micro Gyroscope) under development. Two types of
problems are highlighted, in view of their critical effect on sensor
performance: fabrication sizes control, and the selection
considerations, for the sensor displacement detection mechanism. The
influence of foreseen deviations and errors, on sensor performance is
shown and compared with relevant data, published during the last years
on micro sensors. Some problematic points are discussed, concerning
micromachining, in future manufacturing environments, of Micro Electro
Mechanical and Optical Systems.
|
|
Porous ceramic water hydrostatic bearings for improved accuracy and performance
|
|
J. Corbett (2), R.J. Almond, D.J. Stephenson, Y.B.B. Kwan
|
|
STC P, 47/1/1998, P.467
|
|
Keywords: water hydrostatic, bearing, ceramic, precision |
Abstract : Demand continues for the supply of machine tools with improved accuracy
and productivity. This necessitates machine structures and spindle
assemblies with much higher static and dynamic stiffness than are
currently available, together with very low levels of thermal drift. The
medium term accuracy of oil hydrostatic bearings has traditionally been
limited by the thermal effects and although aerostatic bearings have
relatively good thermal characteristics they suffer from a low relative
stiffness and load capacity. New concepts are therefore required, and
the authors describe a programme which is using fundamental principles
to develop a new improved generation of porous bearings.
|
STC S |
|
Surface modification of ceramics by laser machining
|
|
H.K. Tönshoff (1), H. Kappel
|
|
STC S, 47/1/1998, P.471
|
|
Keywords: surface treatment, laser, ceramic |
Abstract : To complement diamond based machining processes, laser beam machining
offers new ways in surface modification of ceramics. An excimer laser
has been used to study the basic mechanism roughening the surface of
silicon carbide. Investigations on different surfaces (lapped, polished)
show a minor influence of the initial topography on the development of a
characteristic cone structure. Microscopic studies identify the crystal
structure and the melting phase as the main influence. The combination
of these effects is responsible for the formation of a regular cone like
structure ('microspherical caps'). A promising application of this
roughening-phenomena is the improvement of adhesive bonding.
|
|
Effect of tool edge geometry on the nanometric cutting of Ge
|
|
D.A. Lucca (2), P. Chou, R.J. Hocken (1)
|
|
STC S, 47/1/1998, P.475
|
|
Keywords: cutting, surface, force |
Abstract : A specially designed ultraprecision instrument for nanometric cutting
was used to investigate the cutting and thrust forces and the surfaces
generated in the orthogonal cutting of Ge. Single crystal diamond tools
with rake angles of 0°, -15°, -30°, and -45° were used over a range of
depths of cut below 500 nanometers. Tool edge geometry and the resulting
workpiece surfaces were characterized with the use of atomic force
microscopy. A significant increase in thrust to cutting force ratio was
observed for decreasing depth of cut and for increasing negative rake
angle. The depth of cut for onset of significant surface fracture also
increased with increasing negative rake angle.
|
|
Effect of surface topography of workpiece on pressure dependence of coefficient of friction in sheet metal forming
|
|
A. Azushima, J. Miyamoto, H. Kudo (1)
|
|
STC S, 47/1/1998, P.479
|
|
Keywords: tribology, sheet metal, topography |
Abstract : In the previous sheet draw tests of AI-Si alloy and aluminum having a
dull surface, the authors found that the coefficient of friction was
constant in the lower pressure range, whilst in the higher pressure
range, it decreased with increasing pressure and the relationship was
qualitatively interpreted from results of the direct observation of
contact behaviour. In the present work, the pressure dependence is
examined, changing the surface topography of workpiece by pre-rolling to
different flattening degrees of surface asperities. From the results of
direct observation of contact behaviour obtained by making use of a
newly developed fluorescence measurement method, the contact model can
be interpreted 3-dimensionally for better surface control.
|
|
Reconstruction of depth-dependent parameter profiles based on photothermal measurements
|
|
G. Goch, H.G. Walther / E.G. Thwaite (1)
|
|
STC S, 47/1/1998, P.483
|
|
Keywords: hardness, non-destructive, sub-surface |
Abstract : Microstructural changes in a near-surface zone, as they appear at the
hardening of steel, machining of ceramics, laser treatments or wear,
occur together with modifications of their thermal properties.
Therefore, the influences of such processes on the surface layer become
detectable non-destructively by photo-thermal means. Today, the
thickness determination of the affected zone via calibration curves is
regarded as state of the art, whereas an increasing attention is focused
on the numerical evaluation of the depth-dependent parameter profile,
i.e. the material changes as a function of depth, mostly obtained by
destructive tests, as yet. This paper presents the theoretical basics of
a parameter profile reconstruction, based on photo-thermally measured
data. It compares analytical solutions, derived directly from the
thermal diffusion equation (TDE), with numerical approaches using the
Finite Difference Method (FDM), both aiming at a quick and
non-destructive control of near-edge affecting processes. Both models
are applied to photo-thermal measurements, leading to calculated depth
profiles of hardness in steel. which are compared with data,
destructively obtained from the same samples using Vickers indentation
techniques.
|
|
Adaptive control for the optimized adjustment of imaging parameters for surface inspection using machine vision
|
|
T. Pfeifer (2), L. Wiegers
|
|
STC S, 47/1/1998, P.487
|
|
Keywords: adaptive control, surface inspection, machine vision |
Abstract : This paper describes a new method for the adaptive control of imaging
parameters in automized machine vision systems. By these new methods
even in case of critical objects, which show metal and specular
reflections or having polished surfaces, the imaging parameters like
illumination are adjusted optimally without any prior knowledge about
the surface characteristics. As a result, an image is generated, which
is almost free of irrelevant information in the image. This optimised
image only contains the ?real" edges actually found on the object's
surface and is free of effects resulting from specular reflections or
shadows. Surface inspection for scratches, texture analysis or for
dimensional measurements becomes much more reliable now.
|
