CIRP ANNALS 2003
|
|
|
|
|
STC A |
|
Development of new concepts and software tools for the optimization of manual assembly systems
|
|
K. Feldmann (1), S. Junker
|
|
STC A, 52/1/2003, P.1
|
|
Keywords: Assembly, Flexible Manufacturing System, Simulation |
Abstract : Due to growing numbers of differing products and variants, assembly
systems with optimized manual workstations have become an efficient
alternative to highly automated but less flexible production systems.
Especially in the final stage of the product assembly, the flexibility
of human employees enables them to meet the requirements for assembling
various products and changing volumes. In order to create highly
efficient production systems based on human work, it is necessary to
develop innovative concepts for the design and organization of manual
assembly structures. Another major issue is the development of software
tools allowing the facility planner to simulate and optimize the
complete design of the assembly structure such as the material flow or
manual workstations, e.g. with respect to ergonomics, before
construction. These requirements have led to a comprehensive research
framework for manual assembly systems.
|
|
Integrating Augmented Reality in the Assembly Domain - Fundamentals, Benefits and Applications
|
|
G. Reinhart (2), C. Patron
|
|
STC A, 52/1/2003, P.5
|
|
Keywords: Assembly, Augmented Reality, Computer-aided planning |
Abstract : Augmented Reality (AR) is a new form of human-machine interaction which
overlays computer-generated information on the real world environment,
e.g. through a semi-transparent, head-mounted display. With AR,
presented information is derived from the real environment and is thus
context-sensitive. Augmented Reality can therefore enhance a user's view
with virtual information that is sensitive to the current state of the
surrounding real world. While Virtual Reality Technology (VRT) is
commonly used in the automotive and aircraft industry, there exists few
research approaches in the field of Augmented Reality. This contribution
gives a detailed introduction to AR systems, and describes the
capabilities and benefits of AR in the field of assembly. As an
application, a modular AR system for guiding manual assembly and for use
in assembly planning is described. Furthermore, a method for integrating
AR into the planning process of manual assembly stations is presented.
|
|
Assembly Reliability Evaluation Method (AREM)
|
|
T. Suzuki, T. Ohashi, M. Asano / T. Arai (1)
|
|
STC A, 52/1/2003, P.9
|
|
Keywords: Design, Quality, Assembly |
Abstract : This paper proposes a new design system for assembly quality evaluation
called AREM. It is based on the assembly fault occurrence model
reflecting both product design and assembly shops. It prevents faults in
assembly shops related to the design of the product. The system has
three distinctive features: estimation of faults caused by design,
extraction of faulty parts or faulty operations, and analysis of fault
phenomena. AREM can distinguish the responsibility of the design and the
shop quantitatively. This method is being used for various products in
practical production lines, and has proven to be effective.
|
|
Rapid Deployment of Reconfigurable Assembly Fixtures using Workspace Synthesis and Visibility Analysis
|
|
Z. Kong, D. Ceglarek (2)
|
|
STC A, 52/1/2003, P.13
|
|
Keywords: Reconfigurable fixture, Workspace synthesis, Visibility |
Abstract : Due to rapid changes in recent market demands, shortened production
ramp-up/launch and model changeover of new products with simultaneous
manufacturing of family of products on a single production line is
becoming inevitable. This requires systematic methods for rapid design
and analysis of reconfigurable fixture workspace synthesis and
visibility. This paper presents an integrated approach for rapid
reconfigurable fixture deployment which is based on (1) the procrustes
analysis integrated with a pairwise optimization for fixture workspace
configurations synthesis; and (2) screen space transformation-based
visibility analysis for rapid fixture calibration. A case study and
simulations illustrate the proposed approach.
|
|
Self-adjustment of Micro-mechatronic Systems
|
|
M. Tichem, B. Karpuschewski (2), P.M. Sarro
|
|
STC A, 52/1/2003, P.17
|
|
Keywords: Micro-assembly, Mechatronic, Self-adjustment |
Abstract : The paper provides an introduction to various methods of creating
composed products in the micro-domain. The methods are evaluated using
different criteria, including the potential to reduce difficult handling
operations. In the second part, a case study is described on
self-adjustment. The components are coarsely aligned with respect to
each other using for instance (semi) automatic production machines. In
the second stage, the components are precisely aligned with respect to
each other using assembly functions that are integrated with the
product. The case considered is opto-electronic devices. On basis of a
MEMS device self-adjustment is used to position optical fibres.
|
|
Automated Handling of Non-Rigid Parts
|
|
G. Seliger (2), F. Szimmat, J. Niemeier, J. Stephan
|
|
STC A, 52/1/2003, P.21
|
|
Keywords: Assembly automation, Handling device, Non-rigid parts |
Abstract : Handling of non-rigid parts is a challenging and promising field of
industrial automation. Specific processes based on various material
properties of textiles, leather, paper, foils emerge into innovative
tools. Flexural rigidity, surface condition, permeability, and geometric
variance determine process requirements. The behavior of materials is
experimentally analyzed and modeled in order to increase process
reliability. Cases of ply separation, clearing of cutting tables,
positioning, and transporting of non-rigid parts are introduced. Areas
of applications in clothing, electronics, and vehicle manufacturing are
presented.
|
|
Simplified Lifecycle Assessment for the Early Design Stages of Industrial Products
|
|
H. Kaebernick (1), M. Sun, S. Kara
|
|
STC A, 52/1/2003, P.25
|
|
Keywords: Environmental design, Impact evaluation, Lifecycle assessment |
Abstract : Simplified Lifecycle Assessment (LCA) methodologies are very useful
tools in the early design stages for estimating the environmental
impacts of product alternatives and for predicting environmental costs
or burdens for manufacturers. A new methodology, presented in this
paper, is based on the analysis of full LCA case studies. It calculates
the product's Environmental Performance Indicator by using two sets of
energy-based and material-based Impact Drivers. Further simplification
can be achieved by grouping the products according to their
material/energy ratio and by using simple regression equations. A wide
range of case studies is used to compare the simplified results with the
full LCA results.
|
|
Pro-active Life Cycle Engineering Support Tools
|
|
J. Duflou, W. Dewulf, p. Sas / P. Vanherck (1)
|
|
STC A, 52/1/2003, P.29
|
|
Keywords: Environmental, Conceptual Design, Life Cycle |
Abstract : The extending responsibility of manufacturers regarding their products'
environmental impact has led to the development of a wide range of Life
Cycle Engineering tools and techniques. However, their efficiency has
yet been limited by the need for detailed input data, typically
unavailable in the early conceptual phases of design, when most
far-reaching improvements can be achieved. This problem particularly
holds true in a design environment of one-of-a-kind products, such as in
many automation and machine design projects, where no previous
generation products are available to provide the required analysis
feedback. This paper presents a set of pro-active support tools that are
specifically developed for the early design phases and cover the
analytical as well as the creative steps of design. On the one hand,
Eco-Cost Estimation Relationships form the core of the Eco-PaS system,
which estimates the technical parameters, needed as input for most
assessment tools, as a function of the functional parameters available
in the concept development phase. On the other hand, the Ecodesign
Knowledge System classifies both knowledge and user situations according
to a common set of domain models in order to supply, at any time,
adequate Life Cycle Engineering guidance, tailored to the specific user
situation.
|
|
Integration of Economics into Engineering with an Application to the Recycling Market
|
|
K. Ueda (1), N. Nishino, S.H. Oda
|
|
STC A, 52/1/2003, P.33
|
|
Keywords: Life Cycle Management, Decision Making, Economics |
Abstract : This paper describes integration of recent economics concepts into
engineering. Direct and indirect effects of new technology on its users
and society depend on the economic system in which it operates. They can
be formulated and analyzed by experimental economics, computational
economics and the market microstructure theory, which have all emerged
recently in economics. We describe how such integration can be done both
in general and with an example: a recycling economy model. An integrated
approach of engineering and economics that treats human behavior, market
structure and technology on an empirical and theoretical basis makes it
possible to describe a process whereby used product units are collected
from consumers for reuse.
|
|
Life Cycle Simulation System for Life Cycle Process Planning
|
|
S. Takata (1), T. Kimura
|
|
STC A, 52/1/2003, P.37
|
|
Keywords: Life cycle, Simulation, Reuse |
Abstract : To realize closed loop manufacturing, it is essential to design product
life cycles and to plan life cycle processes properly. Life cycle
simulation has been recognized as an effective tool in this direction.
In this paper, we present a life cycle simulation system developed as a
general tool for life cycle design and management. The system includes
functions for modelling and controlling each life cycle process in a
flexible manner. The system maintains usage history of products and
parts independently taking the reuse of parts into account. Examples of
the simulation are shown for both a rapid life cycle scenario and for a
part sharing scenario over the product generations.
|
STC C |
|
Creation of Flat-End V-Shaped Microgroove by Non-Rotational Cutting Tool
|
|
Y. Takeuchi (1), M. Murota, T. Kawai, K. Sawada
|
|
STC C, 52/1/2003, P.41
|
|
Keywords: Micromachining, Non-rotational cutting, Flat-end microgroove |
Abstract : The study deals with the creation of V-shaped microgrooves with
flat-end, which play an important role in case of generating
intermittent grooves. Microgrooves by use of rotational cutting tool
have a long radius in disengagement from the workpiece. Thus, two
cutting methods by use of non-rotational cutting tool are devised so
that V-shaped microgrooves with flat-end can be created. The first
method makes use of straight chips generated under some cutting
condition. Non-rotational cutting tool compresses the chips at the
groove end and cuts the excessive parts of chips over the plane. The
second method is to transcribe the surface of a tool sticked
perpendicularly into a workpiece. As a result, it is experimentally
found that the methods enable the creation of flat-end microgrooves.
|
|
Development of Drill Geometry for Burr Minimization in Drilling
|
|
S.L. Ko, J.E. Chang / S. Kalpakjian (1)
|
|
STC C, 52/1/2003, P.45
|
|
Keywords: Burr, Drilling, Burr Minimization |
Abstract : The researchers carried out drilling tests using drills of various
shapes to determine burr minimization. The ultimate objective of this
study was to develop a compatible drill shape to minimize burr
formation. For the experiment general carbide drills, round drills,
chamfer drills and step drills are designed and manufactured. Burrs are
generated under various cutting conditions using four different
materials. A laser sensor was used to measure the burr dimensions. As a
result of the experiments, step drill with specific step angle and step
size is suggested for burr minimization.
|
|
Theoretical Estimation of Machined Surface Profile Based on Cutting Edge Movement and Tool Orientation in Ball-nosed End Milling
|
|
Y. Mizugaki, K. Kikkawa, H. Terai, M. Hao / T. Sata (1)
|
|
STC C, 52/1/2003, P.49
|
|
Keywords: Ball end milling, Machined surface geometry, Geometric simulation |
Abstract : This paper presents the theoretical estimation method of machined
surface profile without actual machining in ball-nosed end milling. The
fundamental simultaneous equations of identifying the cusp height at any
point of a workpiece in the simulated surface have been successfully
derived from the geometric relationship between the cutting edge
movement and the normal line at the point. By the numerical calculation,
the machined surface profile can be estimated and illustrated
graphically. It was found that the maximum and minimum cusp heights
exist in a narrow range of tool orientation less than 3 degrees near the
normal direction.
|
|
Effects of Synchronizing Errors on Cutting Performance in the Ultra-High-Speed Tapping
|
|
J.H. Ahn, D.J. Lee, S.H. Kim, H.Y. Kim, K.K. Cho (1)
|
|
STC C, 52/1/2003, P.53
|
|
Keywords: Tapping Torque, Thread Quality Synchronizing Error |
Abstract : Synchronizing errors between the spindle motor and the z-axis motor
directly influences the cutting characteristics in tapping, because the
tapping process is accomplished by synchronizing the movement of the
z-axis with the revolutionary spindle motion. The excessive
synchronizing error can cause tap breakage due to the abrupt increase of
cutting torque or damage the thread accuracy by overcutting the already
cut threads. This paper describes the effects of the synchronizing
errors on the cutting performance in the ultra high-speed tapping and
presents a minimum level of synchronizing errors necessary to maintain
the quality of the cut thread.
|
|
Development of a High Performance End Mill - Based on the Analysis of Chip Flow Generated by Curved Rake
|
|
Y. Kimura / H. Takeyama (1)
|
|
STC C, 52/1/2003, P.57
|
|
Keywords: End milling, Chip, Chip flow simulation |
Abstract : To achieve high efficiency machining with end mills, the analysis of
chip flow is necessary. Firstly, the constraints which a curved rake
face gives to chip flow are analyzed, and the existence of the third
component of angular velocity of the chip, which is different from those
of up-curl and sideward curl, is found. Secondly, based on the analysis,
a simulation model of chip flow is proposed, thus leading to the
development of a high performance end mill. Finally, the chip
configurations and chip flow obtained by the simulation are compared
with those observed in actual cutting tests for verification.
|
|
Tribological Characteristics and Cutting Performance of Lubricant Esters for Semi-dry Machining
|
|
T. Wakabayashi, I. Inasaki (1), S. Suda, H. Yokota
|
|
STC C, 52/1/2003, P.61
|
|
Keywords: Machining, Fluid, Environment |
Abstract : In semi-dry machining, a very small amount of a lubricant plays an
important role to achieve a successful operation. However, there has so
far been little investigation on the tribological behavior of lubricants
for semi-dry application in connection with their cutting performance.
To understand the tribological characteristics of such lubricants,
therefore, fundamental examinations are made with the aid of a
controlled atmosphere machining apparatus. Some practical operations of
semi-dry machining are also carried out using several biodegradable
lubricant esters. These esters demonstrate the satisfactory cutting
performance and their effectiveness is discussed in detail with their
lubricating action.
|
|
Supernitrides: A novel generation of PVD hardcoatings to meet the requirements of high demanding cutting applications
|
|
G. Erkens, R. Cremer, T. Hamoudi, K.-D. Bouzakis (1), J. Mirisidis, S. Hadjiyiannis, G. Skordaris, A
|
|
STC C, 52/1/2003, P.65
|
|
Keywords: PVD, Milling, Supernitride coatings |
Abstract : Based on a unique sputtering technology using highly ionized plasmas a
novel grade of high performance hard coatings, the Supernitrides with
macro free morphology were developed. Within the scope of the
investigations described, a characteristic (Ti,AI)N based Supernitride
variant, with an AIN content close to the conductivity limit of
65-67mol-%37; AIN was deposited on cemented carbide inserts. The films
mechanical properties were extracted by means of nanoindentations and
impact tests and compared to the corresponding ones of an effective
state of the art (Ti46AI54)N coating. Milling investigations, conducted
with both previous mentioned coatings, demonstrated the enhanced cutting
performance of the applied Supernitride coating, especially at elevated
cutting temperatures.
|
|
Gains Achieved by Using New Generations of Plastic Injection Mold Steels
|
|
C. Le Calvez (3), G. Poulachon, B. Coulon, A. Ponsot, M. Dessoly, A. Moisan (1), J. Rech
|
|
STC C, 52/1/2003, P.69
|
|
Keywords: Mold Steel, Modelling, Milling |
Abstract : The analysis of the plastic injection mold market shows the interest of
reducing milling costs; the improvement of mold steel machinability is
one response to rough milling. The quantification of the gains offered
by new mold steels requires the development of more accurate and
suitable comparison methods to appreciate the response to rough milling
with toric milling cutters. The methods proposed in this paper take into
account more reliable tool-life criteria. Results of comparison tests
are analysed from scientific, technological and economical points of
view. Moreover, the deduced models lead to a better understanding of the
respective roles of each parameter.
|
|
Wear Mechanisms of New Tool Materials for Ti-6Al-4V High Performance Machining
|
|
N. Corduan, T. Himbert, G. Poulachon, M. Dessoly, M. Lambertin, J. Vigneau (1), B. Payoux
|
|
STC C, 52/1/2003, P.73
|
|
Keywords: Titanium-alloy, Ceramic-tools, Wear |
Abstract : Nowadays, Ti-6Al-4V turning is mastered for cutting speed lower than 60
m/min by using carbide and high-speed steel tools. At higher cutting
speed, chemical and mechanical properties of Ti-6Al-4V cause complex
wear mechanisms such as adhesion and diffusion. Thus, to machine over
100 m/min without using high-pressure cooling, new tool materials need
to be tested and their behaviour understood. This paper presents the
interactions between polycrystalline diamond (PCD), cubic crystalline
boron nitride (CBN), and TiB2 coated carbide with titanium based alloy.
The different wear patterns are not only strongly linked to the chemical
reactions, but also to the different phase changes, which occur with PCD
and CBN tools.
|
|
On the measurement and prediction of temperature fields in machining AISI 1045 steel
|
|
M.A. Davies (2), Q. Cao, A.L. Cooke, R. Ivester
|
|
STC C, 52/1/2003, P.77
|
|
Keywords: Measurement, Finite Element Method, Temperature |
Abstract : Infrared microscopic measurements of the temperature fields at the
tool-chip interface in steady-state, orthogonal, machining of AISI 1045
steel are presented for a range of chip thicknesses. The measurements
are verified using an energy balance method and simple finite difference
calculations (see [14]). These results are compared to the predictions
of a finite element calculation using a commercial package for three
different material models obtained from the literature. Results are
highly dependent on the material model and friction behavior, indicating
that caution be used when finite element analysis is to predict rather
than interpret machining temperatures.
|
|
Cross Reference Models for Estimating Unknown Principal Force
|
|
M. Dölen, B. Kaftano?lu (1), R.D. Lorenz
|
|
STC C, 52/1/2003, P.81
|
|
Keywords: Cutting, End-milling, Modeling |
Abstract : This paper focuses on the problem of estimating the unknown principal
cutting force component with the available knowledge on the other
component. The paper presents two compact (end-milling) process models.
Using these models, two cross-reference models, which explore the
functional relationships among the free parameters of these models, are
developed. Within the framework of constructing an unknown force
component, the estimation performance of the proposed models along with
their inherent limitations are assessed through rigorous experimental
study in this paper.
|
|
Development of a Five-axis Milling Tool Path Generation Algorithm based on Faceted Models
|
|
B. Lauwers (2), G. Kiswanto, J.-P. Kruth (1)
|
|
STC C, 52/1/2003, P.85
|
|
Keywords: Computer aided manufacturing (CAM), Milling, Faceted model |
Abstract : This paper describes the development of a 5-axis milling tool path
generation algorithm based on faceted or tessellated models. In a first
step, the developed algorithm optimises the tool inclination angle for
maximal material removal rate in each cutter contact point. This is
obtained by matching the tool profile of a flat end cutter with a
temporary spline representing the curvature of the part surface in the
tool contact point. In a second step, the elimination of gouging between
the tool and the surface and a smooth behaviour of the tool inclination
angle along the tool path is obtained by a combination of tool
inclination angle adaptation and tool lifting along the normal vector.
Finally, the paper describes some experimental results.
|
STC Dn |
|
Knowledge Structuring for Function Design
|
|
B.R. Meijer, T. Tomiyama (2), B.H.A. van der Holst, K. van der Werff
|
|
STC Dn, 52/1/2003, P.89
|
|
Keywords: Design, Function, Knowledge Management |
Abstract : Well-structured functional knowledge is essential to conduct function
design as stated by well-known design methods, including Suh?s axiomatic
design approach and one of Pahl and Beitz. Innovative design is a
consequence of combining different types of knowledge sources, and
obviously requires well-structured functional knowledge. The paper
focuses on Suh?s axiomatic design approach. Through a design example,
the paper shows that his first axiom (functional independence axiom)
depends on such well-structured knowledge. This confirms that good
design results not from functional independence of functional
requirements but from such well-structured functional knowledge.
|
|
Design Knowledge Management with Reconstructible Structure
|
|
H. Koh, S. Ha, T. Kim, H.M. Rho (2), S.H. Lee
|
|
STC Dn, 52/1/2003, P.93
|
|
Keywords: Knowledge, Design, Knowledge representation |
Abstract : Critical issue in knowledge management is how to increase the
adaptability of knowledge as well as how to reconstruct similar
knowledge. In order to construct the design knowledge for new products,
designers need to reconstruct the design knowledge with new
relationships. A new design knoledge expression method, Design DNA, is
proposed in this work for representing complicated relationships of
design knowledge. Design DNA facilitates rearrangement of design
knowledge and promotes the flexibility of knowledge structure. Design
DNA is based on Layout-oriented domain knowledge and Function-oriented
domain knowledge, which enables to generatee new design knowledge that
will result in new part geometries for given constraints on the part
functions.
|
|
Structure of Failure Knowledge Database and Case Expression
|
|
Y. Hatamura (1), K. iino, K. Tsuchiya, T. Hamaguchi
|
|
STC Dn, 52/1/2003, P.97
|
|
Keywords: Failure, Recognition, Knowledge |
Abstract : There are a number of failure databases that record information about
events that have made negative effects on people, organizations, and the
society. Although they serve the purpose of recording the events, they
fail to prevent similar failures from repeating. The reason is the
poorly organized information data and lack of impact on the information
receiver. This paper proposes a data structure and an effective way of
displaying the failure case information so the receiver understands the
case and makes use of the information by avoiding the failure in similar
situations and even leading the way to creation.
|
|
Biomimetics Applied to Centering in Microassembly
|
|
L.H. Shu (2), T.A. Lenau, H.N. Hansen (2), L. Alting (1)
|
|
STC Dn, 52/1/2003, P.101
|
|
Keywords: Design methodology, Microassembly, Positioning |
Abstract : This paper describes the application of a biomimetic search method to
develop ideas for centering objects in microassembly. Biomimetics
involves the imitation of biological phenomena to solve problems. An
obstacle to the use of biomimetics in engineering is knowledge of
biological phenomena that are relevant to the problem at hand. The
method described here starts with an engineering problem, and then
systematically searches for analogous biological phenomena using
functional keywords. This method is illustrated by finding and using
analogies for the problem of positioning and centering objects during
microassembly. Relevant phenomena identified involve microtubule
organizing centers, photosystems, and retinal ganglion cells.
|
|
Designing Productive Manufacturing Systems without Buffers
|
|
T. Freiheit, M. Shpitalni (1), S.J. Hu, Y. Koren (1)
|
|
STC Dn, 52/1/2003, P.105
|
|
Keywords: Productivity, Manufacturing System Performance, Reconfigurable |
Abstract : Modern industrial practice is to minimize work-in-process in order to
eliminate inventory-carrying costs and quickly detect quality problems.
Reduced work-in-process results from eliminating in-process buffers
between operations in serial lines, but is accompanied by decreased
system efficiency. Inventories are created before system expansion in
order to offset production lost during construction. Furthermore, serial
line expansion implies doubling line output. In reconfigurable
manufacturing systems, new configurations that have not yet been fully
explored by industry can be used to compensate for loss of buffered
system isolation failure, creation of inventories, and step-size
production expansion. Numerical models are applied to predict
productivity and explicitly show the equivalency of alternative
configurations to buffered serial transfer lines. Parallel-serial
configurations as well as the newly proposed reserve capacity
configurations are examined.
|
|
Integrative Design Environment to Improve Collaboration between Various Experts
|
|
F. Noel, D. Brissaud (2), S. Tichkiewitch (1)
|
|
STC Dn, 52/1/2003, P.109
|
|
Keywords: Co-operative Design, Knowledge Integration, Information Sharing |
Abstract : This paper deals with the instrumentation of the collaboration between
actors of various knowledge and know-how. Computer Aided Design
technology lead to many resources supporting the digital mock-up. The
CAD vendors answer integrates various software to deliver a single
environment for every design activity. As an alternative, the paper
describes an integrative environment. We assume that innovative design
is based on the various and heterogeneous resources. Then we propose a
common framework where any existent or future resources will connect to
share knowledge about the product. Concepts handled by the integrative
environment and technologies to support it are discussed.
|
|
Mechanical Bus for Modular Product Design
|
|
P. Gu (2), M. Slevinsky
|
|
STC Dn, 52/1/2003, P.113
|
|
Keywords: Design, Module, Mechanical Bus |
Abstract : Modular products consist of detachable modules that can be manufactured,
assembled, and serviced separately and may be reusable, recyclable, or
remanufacturable upon product retirement. Thus, modular design can
provide benefits to many aspects of product life cycle. To realize these
benefits, the connections between modules must be designed to facilitate
operations for parallel manufacturing, assembly as well as post product
life activities. This paper presents a new concept of Mechanical Bus for
facilitating modular and platform product design. The characteristics
and features of Mechanical Buses have been identified including bus
functions, locking and release mechanisms, positioning and locating
features and so on. A design method for modular platform design using
Mechanical Buses has also been developed. Examples and a case study will
be included to illustrate the Mechanical Bus and modular platform
product design method.
|
|
Product Platform Identification and Development for Evolutionary Customization
|
|
G.Q. Huang, S. Bin , G. Halevi (1)
|
|
STC Dn, 52/1/2003, P.117
|
|
Keywords: Product Development, Design Theory, Product Platform |
Abstract : This paper is mainly concerned with the identification of an embryonic
product platform from a family of products whose composition,
configuration and characteristics are represented by Attributed Graphs.
The problem becomes that of identifying the largest isomorphic sub-graph
with the highest similarity. An algorithm is proposed for solving this
problem together with several novel concepts.
|
|
Customizability Index Based on Information Content
|
|
J. Jiao, M.M. Tseng (1)
|
|
STC Dn, 52/1/2003, P.121
|
|
Keywords: Design, Product, Customization |
Abstract : Developing product platforms has been recognized as an effective means
to implement mass customization. This paper focuses on the
customizability issue of design, that is, to evaluate the cost
effectiveness of a design to be customized to meet individual customer
needs. A customizability index is proposed to facilitate the analysis of
customizability from both the customers and the manufacturer
perspectives. It involves two dimensions. One is about the intrinsic
nature of a design easy to be customized. The other is regarding the
customer-perceived value of customization. The utility theory is
introduced to model the customer-perceived value of each individual
product feature. Conjoint analysis is introduced to explore customer
preference for multiple product features. The customizability index is
measured based on the information content metric. Customizability
analysis manifests itself through the maximization of customer-perceived
value while exploiting the potential of design to be customized
specified by optimal customizability indices.
|
|
Reconstruction of Freeform Objects with Arbitrary Topology Using Neural Networks and Subdivision Techniques
|
|
F.-L. Krause (1), A. Fischer (2), N. Gross, J. Barhak
|
|
STC Dn, 52/1/2003, P.125
|
|
Keywords: Reverse engineering, Neural network method, Subdivision method |
Abstract : In reverse engineering, laser scanned data is reconstructed into a CAD
model. This paper presents a new reconstruction approach that integrates
neural networks with subdivision techniques. The neural network
technique creates a triangular mesh that approximates the shape of an
object and detects its topology, where the subdivision approach applies
smooth surfaces onto this mesh. The advantage of this method is that the
reconstruction can be applied on objects with arbitrary topology, and
the final model can be integrated with traditional CAD systems using a
NURBS representation that preserves continuity. The feasibility of the
method is demonstrated on freeform objects with arbitrary topology.
|
|
Geometric Simulation of NC Machining based on STL Models
|
|
Z.D. Zhou, J.D. Zhou, Y.P. Chen, S.K. Ong, A.Y.C. Nee (1)
|
|
STC Dn, 52/1/2003, P.129
|
|
Keywords: Machining simulation, Geometric modelling algorithm, STL model |
Abstract : Presently, simulation models in virtual CNC machining simulation can be
generated using commercial CAD software to provide dynamic 3D
interactive virtual environments specifically designed for visualizing
and analyzing the functionality of CNC machine tools and the material
removal processes. However, these models generated using different CAD
software have distinct individual formats, and are difficult to use in
another simulation environment. This paper proposes to use the STL
(stereolithography) models as the common models in machining simulation
for bridging the incompatibility between different CAD software systems.
The simulation results in the STL model format can be immediately used
in rapid prototyping to produce the prototype and design changes can be
reflected quickly from these prototypes. This will serve as a useful
guide for the designers to make the necessary changes along the design
process.
|
|
Integrated Tolerancing Process for Conceptual Design
|
|
J.-Y. Dantan, N. Anwer, L. Mathieu (2)
|
|
STC Dn, 52/1/2003, P.135
|
|
Keywords: Design process, Tolerancing Synthesis, Information modelling |
Abstract : For car and aircraft industries, the management of geometrical
variations has become an important issue in product design process and
concurrent engineering. Indeed, designers need to manage dimensional and
geometrical tolerances and to know information that contributed to their
determination. The goal here is to put tolerancing in a concurrent
engineering context. There are important questions that would need to be
looked upon: How to integrate the tolerance synthesis in the design
process? How to ensure the transition from function to geometrical
specifications on parts? How to keep traceability of tolerances during
the design process? Few answers exist today in academic works and there
are few supports in CAD systems. Therefore, to build a coherent data
model taken into account tolerances, we describe in this paper a
multi-level approach that enables a tolerancing process integrated with
conceptual design. The first level integrates information relating to
functional aspects of an assembly. The second describes the structure of
the assembly, and concerns the integration of functional needs and
technological solutions. The last level translates functional
requirements into geometrical requirements between/or on parts of the
products, and provides the geometrical specifications on each part
satisfying the geometrical requirements. This multi-level architecture
is represented as an object oriented data model based on UML (Unified
Modelling Language) that enable data management for functional
tolerancing in design and keeping traces when querying about data.
|
STC E |
|
New Ferro Powder for Selective Laser Sintering of Dense Parts
|
|
J.P. Kruth (1), L. Froyen, M. Rombouts, J. Van Vaerenbergh, p. Mercelis
|
|
STC E, 52/1/2003, P.139
|
|
Keywords: laser sintering, iron powder, rapid prototyping |
Abstract : The paper describes a new powder composition specially developed for
selective laser sintering (SLS). The aim is to obtain a ferro powder
that can be sintered without need for a (sacrificial) polymer binder and
that results in quasi dense parts that do not need any post-processing
like furnace sintering, infiltration or HIP. The powder is a mixture of
different types of particles (Fe, Cu, Ni and Fe3P). The composition and
mixture ratio are justified by using phase diagrams. The powder has been
tested using an own developed Nd:YAG SLS machine. The influence of
process parameters (laser power, scan velocity, scan spacing and scan
strategy) and the microstructural characteristics have been
investigated. Attention is devoted to the binding mechanism (liquid
phase sintering, through melting) and to the quality of resulting parts
(density, balling effect, ?).
|
|
Modelling and Simulation of Micro-EDM
|
|
Z.Y. Yu, J. Kozak, K.P. Rajurkar (1)
|
|
STC E, 52/1/2003, P.143
|
|
Keywords: Electrical Discharge Machining, Modelling, Simulation. |
Abstract : In micro EDM, simple-shaped tools are being used to machine complex 3D
micro features because of the cost and difficulty in fabricating
multiple complex-shaped micro electrodes. However, the tool wear
adversely affects the accuracy of machined micro features. Therefore, a
theoretical model for surface profile generation which takes into
account the effect of tool wear is needed. This paper presents such a
model and a simplified simulation algorithm. The experimental results of
micro and macro EDM generated surface profiles confirm the validity of
the proposed mathematical model and the simulation algorithm.
|
|
High Speed 3D Milling by Dry EDM
|
|
M. Kunieda (2), Y. Miyoshi, T. Takaya, N. Nakajima, Z.-B. Yu, M. Yoshida
|
|
STC E, 52/1/2003, P.147
|
|
Keywords: EDM, high speed machining, dry process |
Abstract : This paper describes the high speed EDM milling of 3D cavities using gas
as the working fluid. In this new process, the molten workpiece material
is removed and flushed out of the working gap with the help of
high-pressure gas flow. The advantages of this technique are the
remarkably small tool electrode wear and the significantly high material
removal rate especially when oxygen gas is used due to the extremely
strong oxidation of steel workpieces. Experiments showed that the
material removal rate increases dramatically when the discharge power
density on the working surface exceeds a certain threshold due to
thermally activated chemical reaction between the gas and workpiece
material. The maximum removal rate obtained was almost equal to that of
high speed milling of quenched steel by a milling machine. The machining
accuracy was considerably better when the gas was sucked through the
pipe electrode than jetted.
|
|
Electrical Discharge Surface Alloying of Ti and Fe Workpiece Materials Using Refractory Powder Compact Electrodes and Cu Wire
|
|
D.K. Aspinwall, R.C. Dewes, H.G. Lee, J. Simao / P. McKeown (1)
|
|
STC E, 52/1/2003, P.151
|
|
Keywords: Electrical discharge machining (EDM), Texture, Surface |
Abstract : The paper reviews the use of metal powders dispersed in the dielectric
fluid and refractory PM electrodes, to initiate workpiece surface
modification during EDM. Experimental work details the effects of EDM
parameters (up to 270 V) on the hardness / composition of the white
layer following die sink machining of AISI H13 tool steel and roll
texturing of 2%37; Cr steel using partially sintered PM electrodes. Similar
data are presented following EDM scanning and wire cutting of standard
Ti alloy Ti-6Al-4V and a ? TiAl. With AISI H13, recast layers were 5-20
µm thick and up to ~1350 HK0.025. When machining Ti-6Al-4V with WC/Co
electrodes, recast microhardness was 600-2900 HK0.025. Wire cutting ?
TiAl generated porous alloyed layers up to 115 µm thick with extensive
cracks and no increase in bulk hardness.
|
|
Layer Generation Process on Work-piece in Electrical Discharge Machining
|
|
N. Mohri (2), Y. Fukusima, Y. Fukuzawa, T. Tani, N. Saito
|
|
STC E, 52/1/2003, P.157
|
|
Keywords: Electrical Discharge Machining, Ceramic, Surface |
Abstract : In recent years, surface modification of metals and machining of
insulating ceramics by electrical discharge machining (EDM) have been
successfully carried out. In surface modification by EDM with
semi-sintered electrodes, worn substances in the gap region form the
material source of the layer generated on the work-piece surface. In the
machining of insulating ceramics by EDM, a crystallized carbon layer or
carbide layer from the working oil covers the surface of the insulator.
Increase in the thickness of the generated layer, however, tends to stop
at a certain maximum value in both surface modification by EDM with
semi-sintered electrodes and machining of insulating ceramics by EDM
processes. In these machining operations, accretion and removal
phenomena occur alternately. In this paper, the mechanisms of machining
insulators and the accretion process are discussed considering the
characteristics of the generated layers on the work-piece surface.
|
|
Effects of Surface Roughness on Solder Bump Formation
|
|
J.-H. Chun (2), W. Hsiao
|
|
STC E, 52/1/2003, P.161
|
|
Keywords: Surface roughness, Precision spray deposition, Electronics |
Abstract : packaging
This paper presents a study of the effects of substrate surface
roughness on droplet bouncing during direct solder bumping, a phenomenon
that strongly affects the deposition efficiency, as well as the final
bump size and shape. A theory was developed to correlate surface
roughness to the potential for droplet bouncing. In addition, an
experimental study was conducted by depositing Sn microdroplets on Au
plated substrates with different surface roughness levels. The
population densities and morphologies of the splats collected were
analyzed to determine the occurrences of bouncing. The results suggest
that a decreass in surface roughness reduces the potential for droplet
bouncing.
|
|
Influence of electrolyte concentration on copying accuracy of precision ECM
|
|
A. De Silva (2) H. Altena (3) J. McGeough (1)
|
|
STC E, 52/1/2003, P.165
|
|
Keywords: ECM accuracy, Electrolyte concentration, Localised dissolution |
Abstract : A precision ECM process, dimensional accuracy ±2 µm, surface finish
0.01 µm Ra, has been developed using narrow inter-electrode gaps (< 50
µm) for mass production of small (100 mm²) component parts. The
electrolyte properties, especially the concentration, play a significant
role in controlling the dimensional accuracy of precision-ECM. The
relationships between the electrolyte concentration and various process
parameters are derived empirically and are utilised in a graphical model
to predict the localisation effects of electrochemical dissolution. By
controlling the localisation effects significant improvements are made
to the dimensional accuracy obtained. Practical examples are used to
validate the model developed.
|
|
Design of Electrode Profile in Electrochemical Manufacturing Process
|
|
D. Zhu (2), K. Wang, J.M. Yang
|
|
STC E, 52/1/2003, P.169
|
|
Keywords: Electrode, Electro-chemical machining, Electroforming |
Abstract : Accurate prediction of electrode shapes is most important in
electrochemical manufacturing process which includes electrochemical
machining and electroforming. In the former process, the electrode
design is focused on the prediction of the cathode tool which
significantly affects the machining accuracy. In the electroforming
process, the anode electrode shape determines the current density
distribution and so the properties of the deposited metal. This paper
proposes a finite element approach to accurately determine these
electrode profiles. The proposed method does not require iterative
redesign process, therefore provides excellent convergence and efficient
computing. Close agreements between theoretical and experimental results
have been observed.
|
|
Selective laser sintering of SiC/Polyamide composites
|
|
K.K.B Hon (1), T.J. Gill
|
|
STC E, 52/1/2003, P.173
|
|
Keywords: Rapid Prototyping, Composite, Selective Laser Sintering |
Abstract : This paper presents an experimental study into the production of
particulate Silicon Carbide/ Polyamide matrix composites via the
selective laser sintering (SLS) process. FEPA standard SiC grit, F240,
was blended with the commercially available Duraform Polyamide to
produce blend compositions of 50 volume percent and 50 weight percent
SiC for direct SLS processing. A full factorial experimental approach
was applied to examine the effects and interactions of laser power, scan
speed, line spacing and layer thickness with regard to the mechanical
and physical properties of composite sintered parts. Analysis of results
and discussions of parameter interactions and individual main effects
especially with regard to part strength are also presented.
|
|
Coalescence Behaviour of Two Metallic Particles as Base Mechanism of Selective Laser Sintering
|
|
F. Klocke (1), C. Wagner
|
|
STC E, 52/1/2003, P.177
|
|
Keywords: Laser Sintering, Metal Powder Processing, Rapid Manufacturing |
Abstract : In many R&D places, the process of Selective Laser Sintering (SLS) of
high performance metals is subject of investigations. An observation
often made in SLS of metals is, that certain materials show a proper
bonding behaviour while others tend to form welding pearls (?balling«
effect). This paper aims to identify and explain process mechanisms
related to this effect. The dominating physical mechanisms are
investi-gated. In addition, it is described which material properties
mainly affect the results. The attained insights are transferred to the
conditions of SLS in a powder bed layer by process modelling and
experimental testing.
|
|
Effects of Powder Geometry and Composition in Coaxial Laser Deposition of 316L Steel for Rapid Prototyping
|
|
A.J. Pinkerton, L. Li / W.S. Lau (1)
|
|
STC E, 52/1/2003, P.181
|
|
Keywords: Laser, prototyping, powder |
Abstract : Multiple layer laser powder deposition has recently been applied to
producing fully dense 3-D metallic engineering parts for rapid
prototyping and tooling. To date, however, the process has been limited
to using only gas-atomised, spherical powders. In this paper, the
feasibility of using water-atomised powders is investigated, based on an
experimental comparison of gas- and water- atomised powders in multiple
layer, laser fused deposition of 316L stainless steel. The work shows
that, despite much lower cost (approximately 25%37; of the price of
gas-atomised powders), the water-atomised, irregular powders have
superior deposition quality in terms of surface finish, deposition
uniformity, microstructures and bonding between layers, compared to the
gas-atomised powders under the same processing conditions, although
deposition rate is lower. Powder geometry and oxygen content differences
of the two powders have been found to be the principal reasons for the
observed effects. Theoretical analyses of the beam-material interaction
processes and melt pool behaviour are presented to explain the observed
phenomena. The results indicate that there are both functional and
economic reasons for using water-atomised powders for this additive
manufacturing application.
|
|
Study of Part Geometric Features and Support Materials in Rapid Freeze Prototyping
|
|
M.C. Leu (2), Q. Liu, F.D. Bryant
|
|
STC E, 52/1/2003, P.185
|
|
Keywords: Rapid, Prototyping, Freezing |
Abstract : This paper describes the investigation of part geometric features and
support materials in the fabrication of ice parts by Rapid Freeze
Prototyping (RFP). The achievable geometric features of the ice part
including the smallest thickness of a wall and the smallest diameter of
a rod are analyzed and expressed as functions of process parameters
including water pressure, nozzle diameter, valve open/close frequency
and duty cycle, and x-y table moving speed relative to the nozzle. The
validity of the predicted results of geometric features from the
analysis is verified using our experimental RFP system. In order to
realize fabricating ice parts of any complex 3-D geometry, support
materials are also studied. The experimental results showed a eutectic
mixture of dextrose and water works well as the support material while a
eutectic mixture of salt and water does not work satisfactorily.
|
|
An Investigation of the Capability Profile of the Three Dimensional Printing Process with an Emphasis on the Achievable Accuracy
|
|
D. Dimitrov, W. van Wijck, K. Schreve, N. de Beer / J. Meijer (1)
|
|
STC E, 52/1/2003, P.189
|
|
Keywords: Rapid prototyping, Accuracy, 3D Printing |
Abstract : A benchmark procedure has been designed to assess the dimensional as
well as the geometric accuracy of currently one of the most widely used
rapid prototyping processes ? the Three Dimensional Printing. It tests
not only linear accuracy but also precision, and repeatability of the
process, as well as its ability to create manufacturing features such as
fillets and draft angles. The presented research results reflect the
necessity to adequately respond to engineering requirements for clearly
meeting dimensional and geometric tolerances and root on several
in-house case studies proving the comparison with established high-end
RP processes.
|
|
Effects of Modal Interactions on Vibration Peformance in Ultrasonic Cutting
|
|
M. Lucas, A. Cardoni, F.C.N. Lim, M.P. Cartmell / J. McGeough (1)
|
|
STC E, 52/1/2003, P.193
|
|
Keywords: Ultrasonic cutting, Nonlinear responses, Vibration |
Abstract : The effects of modal interactions and nonlinear response characteristics
can hamper implementation of high power ultrasonic technologies, due to
the resulting modal coupling, increased stress, audible noise levels and
poor control of the operating response. These different adverse
responses are illustrated by characterising the vibration behaviour of
single-blade and multi-blade ultrasonic cutting systems. This paper
proposes design strategies to eliminate the effects of modal
interactions, by focusing on reducing the number of vibration modes, and
to reduce the effects of nonlinear responses, by serial coupling of
tuned components with appropriate cubic softening and hardening response
characteristics.
|
STC F |
|
A New Rolling Process for Strips With a Defined Cross Section
|
|
R. Kopp (1), P. Boehlke
|
|
STC F, 52/1/2003, P.197
|
|
Keywords: Forming, Rolling, Profile |
Abstract : A new rolling process is being developed for producing cold rolled
strips with a defined cross section. These strips feature differences in
thickness up to 50%37; perpendicular to the rolling direction. A special
roll system is used to achieve a material flow exclusively in the
direction of the strip width. As a consequence the strip width is
increased significantly. In this way a wide variety of different cross
sections can be produced. The range of application for these kind of
strips cover novel load-adapted and load-optimized struc-tures with
different thicknesses, e.g. special profiles and special section tubes.
|
|
Development of a Highly Flexible Incremental Roll Forming Process for the Manufacture of a Doubly Curved Sheet Metal
|
|
S.J. Yoon, D.Y. Yang (1)
|
|
STC F, 52/1/2003, P.201
|
|
Keywords: Sheet metal, Roll, Incremental forming |
Abstract : A flexible incremental roll forming process has been developed by
adopting the advantages of the incremental forming process and the roll
forming process: i.e., inherent flexibility of the incremental forming
process and continuous bending deformation of the roll forming process.
It has an adjustable roll set as a forming tool composed of one upper
center roll and two pairs of lower support rolls, which plays a key
role. Through the experiments, it is shown that the improved forming
method of the proposed process is effective in the manufacture of
various doubly curved sheet metals, and the proposed relationship of the
experimental parameters and the radius of curvature of the formed sheet
boundary is useful to control the final shape.
|
|
Closed loop control of the 3D bending process
|
|
K. Kuzman (3) / M. Geiger (1)
|
|
STC F, 52/1/2003, P.205
|
|
Keywords: 3D bending, process control, cold forming |
Abstract : Mechanical properties of the incoming material have a major effect on
the shape stability of 3D wire bent products. The study of the wire
straightening process prior to final bending showed that it could
efficiently be used to control the mechanical properties as well as
straightness of the wire. The core of the stabilization algorithm is a
slightly modified Prager?s flow rule considering material hardening or
softening as a result of accumulated small reverse plastic strains. Flow
stress calculation of the incoming material is based on the measured
transverse roller forces. The obtained data define the needed
repositioning of the straightening rollers. The new settings stabilize
the wire material properties, which reflect in the shape of the 3D bent
product.
|
|
A Geometric Approach to Modelling Friction in Metal Forming
|
|
P. Becker, H.J. Jeon, C.C. Chang, A.N. Bramley (1)
|
|
STC F, 52/1/2003, P.209
|
|
Keywords: Forging, Friction, Ring test |
Abstract : When simulating metal forming processes it is common practice to
describe the friction by using the Coulomb or Tresca model and to assume
that the conditions are constant throughout the process. This paper
describes an alternative approach that seeks to describe friction by
modelling the geometric surface roughness of the tools. Using the ring
test analytically a relationship has been established between surface
geometry and the friction factor. This model has been validated
experimentally also using the ring test. Such a system provides an
opportunity to model friction more flexibly and accurately.
|
|
Determination of forming limit diagrams ? a new analysis method for characterization of materials´ formability
|
|
M. Geiger (1), M. Merklein
|
|
STC F, 52/1/2003, P.213
|
|
Keywords: Forming, Sheet Metal, Failure Criterion |
Abstract : This paper introduces a new analysis method for characterization of
materials´ formability independent of individual expertise. Therefore
forming limit diagrams (FLDs) are determined using the Nakazima method.
Investigations on the influence of the analysis method and the failure
criterion in detail will be presented. The new analysis method avoids
misinterpretation of the forming limits of any material and the FLD. The
forming behavior of materials has to be recorded with a frequency up to
20 Hz, in order to detect the forming limits within a sequence of
pictures from onset of necking to failure by cracking.
|
|
Determination of True Stress-Strain-Curves and Normal Anisotropy in Tensile Tests with Optical Strain Measurement
|
|
H. Hoffmann (2), C. Vogl
|
|
STC F, 52/1/2003, P.217
|
|
Keywords: Anisotropy, FEM, Tensile test |
Abstract : This paper describes a method to measure the flow curve which undergoes
necking and normal anisotropy as a function of equivalent strain using
an optical measurement system. The flow stress was determined by
modifying Siebel and Schwaigerer?s model. Normal anisotropy was regarded
as a function of equivalent strain. Comparing with the experiment of the
stretch forming process, the simulation using improved material
properties shows the better strain distribution than the results using
conventional material properties in high strain areas.
|
|
Simultaneous Determination of Flow Stress and Interface Friction by Finite Element Based Inverse Analysis Technique
|
|
H. Cho, G. Ngaile / T. Altan (1)
|
|
STC F, 52/1/2003, P.221
|
|
Keywords: Finite element method (FEM), Material, Inverse Analysis |
Abstract : A finite element based inverse analysis technique has been developed to
determine the flow stress and friction at the tool/workpiece interface
simultaneously from one set of material tests. The inverse problem is
aimed at minimizing the error between experimental data and predictions
made by rigid-plastic finite element simulations. The ring compression
test and the modified limiting dome height test (sheet blank with a hole
at center stretched with a hemispherical punch) were selected for
evaluating the method for bulk forming and for sheet forming,
respectively. The determined flow stress data were compared with
corresponding data obtained independently using the well-lubricated
cylinder compression test and hydraulic bulge test. Results show that
the method discussed in the study is efficient and accurate.
|
|
Development of an Optical Sensor for the Measurement of the Material Flow in Deep Drawing Processes
|
|
E. Doege (1), R. Schmidt-Jürgensen, S. Huinink, J.-W. Yun
|
|
STC F, 52/1/2003, P.225
|
|
Keywords: deep drawing, sensor, control |
Abstract : In this paper a new optical sensor and its applications are presented.
The prediction of faults that occur during the layout of deep drawing
processes (e.g. cracks) remains a significant problem. Therefore, at the
IFUM a new optical sensor principle has been developed for the
contact-free recording of the material flow. The sensor recognizes
special patterns on the sheet surface. The measured material flow can be
used for the determination of local strain. The optical sensor could be
utilized instead of using expensive optical systems or manual methods
(e.g. with a measurement grid) for the deformation measurement, which
still require a special preparation of the specimen. Furthermore, the
material flow can be used as the controlled variable for the closed loop
control of deep drawing processes with varying blank holder forces along
the flange. On the one hand the data recorded with the new optical
sensor is used to increase the quality of the FE-simulation. On the
other hand a press with a multipoint drawing tool will be regulated by
the control loop. A fuzzy controller is under development for the
automatic connection between the material flow and the blank holding force.
|
|
Process Stability in the Tube Hydroforming Process
|
|
P. Groche, R. Steinheimer, D. Schmoeckel (1)
|
|
STC F, 52/1/2003, P.229
|
|
Keywords: Tube High Pressure Forming, Process Stability, Control |
Abstract : Material properties have a significant influence on the process
stability in tube hydroforming, particularly in series production.
Mainly tubular material with longitudinally oriented welding lines is
used in tube hydroforming. A new test method was developed to examine
the important properties of the semi-finished product, such as flow
pressure or maximum circumferential elongation during the hydroforming
process. Knowing these parameters, the process control can be adjusted
according to the differences of the varying semi-finished product
charges. Another option to improve the process stability is a new
process control strategy, which uses the volume flow instead of the
conventionally used pressure as control variable. A volume control
enables the production of sound parts made of different materials with
varying wall thicknesses without changing the process control settings.
|
|
Homogenisation of Thickness through High Viscous Fluid Flow
|
|
F. Vollertsen (2), H. Schulze Niehoff
|
|
STC F, 52/1/2003, P.233
|
|
Keywords: Sheet metal, forming, flow |
Abstract : This paper describes investigations on new ways to influence sheet metal
forming processes through a new parameter. The new adjustable parameter
is a shear stress on the surface of the sheet applied during the forming
process through high viscous fluid flows. Parallel and hourglass shaped
tensile test specimen were investigated, whereby a fluid flow was
applied from the ends to the middle of the specimens. The results
clearly show a significant influence of the high viscous fluid flows on
the specimens. For the hourglass shaped specimen it could be shown that
the inhomogeneous cross section distribution could be compensated by the
applied shear stresses, so that a homogenous sheet thickness
distribution was reached.
|
|
Multi-Stage Cold Deep Drawing of Long Pure Titanium Cups Using Coloured Sheets for Prevention of Seizure
|
|
K.I. Mori, T. Murao, Y. Harada / T. Matsuo (1)
|
|
STC F, 52/1/2003, P.237
|
|
Keywords: Forming, Titanium, Tribology |
Abstract : Long pure titanium cups were formed by multi-stage cold deep drawing
using commercial coloured titanium sheets for preventing seizing. The
titanium sheets have sufficient ductility and high r-value for the deep
drawing, whereas the seizure tends to occur during the deep drawing due
to high reactivity with die materials. The coloured pure titanium sheets
were treated by electrochemical coating so as to get oxide surface layer
effective for preventing the seizing. By the use of commercial coloured
sheets, the investment of coating machines can be avoided in sheet metal
forming makers and the quality of the oxide layer can be controlled. The
effects of the thickness of the oxide layer, die materials and
lubricants on the occurrence of seizure in multi-stage deep drawing were
examined. It was found that the coloured pure titanium sheets have
sufficient ability in preventing the seizure in multi-stage deep drawing
processes.
|
|
Pneumatic Bulging of Magnesium AZ 31 Sheet Metals at Elevated Temperatures
|
|
K. Siegert (1), S. Jäger, M. Vulcan
|
|
STC F, 52/1/2003, P.241
|
|
Keywords: Magnesium, Pneumatic, Sheet metal |
Abstract : This paper deals with forming magnesium sheet metal components like auto
body parts by pneumatic bulging. Furthermore, this paper deals with the
evaluation of true stress-true strain curves as well as with forming
limit curves determined by pneumatic bulging at temperatures up to
350°C. It can be shown that magnesium AZ31 is quite good formable at
temperatures in the range of 250°C to 350°C. Outgoing from these
fundamental investigations, an auto body sheet metal component was
formed by pneumatic bulging at a temperature of about 300°C.
Furthermore, the strains over the component were measured with an
automated grid analysis. This analysis shows a nearly equal distribution
of the strains over the component.
|
|
Reduction of blanking noise by controlling press motion
|
|
M. Otsu, C. Yamagata, K. Osakada (1)
|
|
STC F, 52/1/2003, P.245
|
|
Keywords: Blanking, Noise, Press Motion |
Abstract : To reduce blanking noise with servo controlled presses, continuous two
steps blanking, in which the punch is stopped at an intermediate
position before breakthrough and soon moved again to finish the process,
is proposed. Plates of carbon steels, 18-8 stainless steel, titanium and
copper are tested. When the punch is stopped just before breakthrough,
the noise can be reduced to a very low level especially for high
strength carbon steel plates. The mechanism of noise reduction in the
process is clarified through the measurement of sound wave and machine
vibration together with short-time FFT analysis.
|
|
On the use of SLS Tools in Sheet Metal Stamping
|
|
G.N. Levy (1), R. Schindel, p. Schleiss, F. Micari (2), L. Fratini
|
|
STC F, 52/1/2003, P.249
|
|
Keywords: Rapid, Tooling, Wear |
Abstract : A few rapid tooling technologies have been recently proposed and among
them Selective Laser Sintering is probably one of the most relevant and
promising. In the paper, the authors report some results of a wide
experimental research on the application of SLS tools in sheet metal
forming. A wear test was carried out to investigate the progressive
degradation of laser-sintered materials in comparison with traditional
cold-work steels. In particular SLS tools were utilized in a sheet metal
stamping process of S-shaped parts: their performances (in terms of tool
wear and dimensional quality of the stamped part) were compared with the
ones of traditional tools.
|
STC G |
|
Chip Formation Mechanisms in Grinding at Low Speeds
|
|
E. Brinksmeier (1), A. Giwerzew
|
|
STC G, 52/1/2003, P.253
|
|
Keywords: Grinding, Chip Formation, Cutting Speed |
Abstract : Grinding processes characterised by cutting speeds as low as 0.3...5 m/s
are becoming more and more important amongst abrasive technologies for
finishing of hardened gears. A number of research work carried out in
this area in the past few years has significantly improved the
understanding of common technological interdependencies. However, there
is still a lack of knowledge about the main chip formation mechanisms at
such low speeds. In order to investigate these mechanisms, single grit
scratching tests and grinding experiments have been performed. The
cutting speed and the chip thickness were identified as main quantities
determining the chip formation process. These results can be used for
design of grinding processes and development of suitable abrasive tools.
|
|
Optimization of Continuous Dress Creep-Feed Form Grinding Process
|
|
C. Guo (3), M. Campomanes, D. McIntosh (3), C. Becze, T. Green / S. Malkin (1)
|
|
STC G, 52/1/2003, P.259
|
|
Keywords: Grinding, Nickel Alloy, Optimization |
Abstract : This paper is concerned with optimization of continuous-dress creep-feed
grinding processes to reduce cycle time and wheel consumption by
adaptively adjusting workspeed and dress infeed based on grinding models
and in-process power monitoring. Heat flux is kept below the fluid
burnout limits to avoid thermal damage to the ground surface. Grinding
forces are controlled below the allowable values to avoid coating cracks
caused by excessive strain on the blade. By implementing this approach,
40%37; cycle time reduction was demonstrated while maintaining the heat
flux and grinding forces below their allowable critical values.
|
|
Temperatures in Grinding of Magnetic Composites - Theoretical and Experimental Approach
|
|
B.W. Kruszynski (2), J. Pazgier
|
|
STC G, 52/1/2003, P.263
|
|
Keywords: Grinding, Thermal Model, Magnetic Composite |
Abstract : The present paper is concerned with grinding temperatures and surface
integrity for grinding of magnetic composites consisting of
sandwich-like layers of brittle magnetic material and soft steel. High
temperatures which are generated during grinding of these magnetic
composites may have a detrimental effect on their magnetic properties if
the grinding temperature exceeds the Curie point of the magnetic
component. A thermal model was developed to calculate the grinding
temperatures in the magnetic composite workpiece. Temperatures measured
in the magnetic composite using embedded thermocouples were found to be
consistent with predictions from the thermal model. Crucial regions in
the magnetic composite were found where the highest temperatures and
temperature gradients occur and where surface integrity may be
destroyed. The range of grinding conditions providing both high
efficiency and good surface quality were found.
|
|
An Investigation of Grinding with Electroplated CBN Wheels
|
|
Z. Shi, S. Malkin (1)
|
|
STC G, 52/1/2003, P.267
|
|
Keywords: Grinding, Cubic boron nitride (CBN), Wear |
Abstract : Grinding of hardened bearing steel with electroplated CBN wheels was
investigated with particular attention to how the wear of the abrasive
grains affects the wheel topography and grinding performance during the
wheel life. Power, surface roughness, and wheel topography data were
obtained throughout the wheel life for internal cylindrical grinding.
Dulling of CBN grains by attrition was found to cause an increase in the
grinding power, but the degree of dulling was restricted mainly by grain
fracture and also by grain pullout. Grain fracture and pullout had a
much smaller effect on the progressive increase in active grain density,
which caused the surface roughness to progressively decrease. Wheel
failure tended to occur by stripping of the abrasive layer when the
radial wear reached about 70%37; ? 80%37; of the grain dimension
|
|
Surface Generation with Engineered Diamond Grinding Wheels: Insights from Simulation
|
|
P. Koshy, A. Iwasaki, M.A. Elbestawi (1)
|
|
STC G, 52/1/2003, P.271
|
|
Keywords: Grinding, Roughness, Simulation |
Abstract : Engineered wheels are a recent innovative development towards consistent
and exceptional performance in fine grinding operations. Abrasive grains
in an engineered wheel are positioned in a specific spatial pattern, as
opposed to random locations in a conventional wheel. The present work
relates to the formulation of a theoretical framework for the design of
engineered wheels in terms of maximizing their performance with respect
to their surface generation characteristics. Computer simulations
indicate that: (i) The distribution of abrasive protrusion height,
rather than its absolute maximum value, determines the roughness of the
ground surface and controls the associated variability, and therefore by
tailoring the distribution appropriately, the performance of the wheel
can be improved significantly, (ii) With an ordered arrangement of
abrasive grains, the finish obtained is a strong function of the axial
offset between adjacent rows of grains, but the best finish achieved
thus is only on the order of that obtained with a conventional wheel,
and (iii) The effect of grain shape on the roughness of the ground
surface is comparable to the inherent process variability.
|
|
Development of a Superabrasive Grinding Wheel with Defined Grain Structure Using Kinematic Simulation
|
|
J.C. Aurich, O. Braun, G. Warnecke / L. Cronjäger (1)
|
|
STC G, 52/1/2003, P.275
|
|
Keywords: Grinding, Simulation, Superabrasive Tool |
Abstract : This paper presents the concept of superabrasive electroplated grinding
wheels based on defined grain structures. The aim is to improve process
stability, minimize heat generation and achieve a high surface quality
while preserving a high material removal rate. Based on geometrical
models, different patterns of grit settings have been investigated by
means of kinematic simulation. Applying the results of the simulation, a
prototype grinding wheel with an optimized defined grain structure has
been constructed. The performance potential of the prototype has been
analyzed through experimental examinations.
|
|
Development of a High-Speed Manufacturing Method for Electroplated Diamond Wire Tools
|
|
Y. Chiba, Y. Tani (2), T. Enomoto, H. Sato (1)
|
|
STC G, 52/1/2003, P.281
|
|
Keywords: Grinding, Wire Tool, Electroplating |
Abstract : Fixed-abrasive multi-wire sawing processes can be used to slice silicon
and quartz crystal due to the introduction of resinoid diamond-wire or
electroplated diamond-wire tools. The latter kind have a higher wear
resistance, but have higher production costs because electroplating is
time consuming. Consequently, it is impractical to use them because they
are too expensive. In this paper, ultra high-speed electroplating using
felt brushes is proposed for manufacturing them. A series of experiments
revealed that production speed is improved 30 times and tools produced
with the new process have a higher wear resistance than commercially
produced tools.
|
|
Lapping of single crystal diamond tools
|
|
Z.J. Yuan (1), Y.X. Yao, M. Zhou, Q.S. Bai
|
|
STC G, 52/1/2003, P.285
|
|
Keywords: Diamond, Lapping, Crystal plane |
Abstract : Lapping is the key technology used in manufacturing process of diamond
tools and diamond jewels. Because of the strong anisotropism and super
hardness of diamond, the material removal rate is very small in its
lapping process. The influence of the crystal anisotropism on removal
rate in diamond lapping is discussed in this paper. A new diamond
crystal orientation method by using laser diffraction is presented,
which can not only be used for the crystal orientation, but also for the
indication of ?soft? directions on crystal planes in lapping. The
mechanism of removal rate anisotropism in diamond lapping is
investigated, and a new explanation for the reasons is proposed. It is
pointed out that the variation of inclination angle between inside (111)
plane (cleavage plane) and lapping surface causes the difference of
friction coefficient and removal rate in diamond lapping. Furthermore, a
new method using ultrasonic vibration for diamond lapping was developed
to improve the removal rate.
|
STC M |
|
Ferraris Sensor - The key for advanced dynamic Drives
|
|
G. Pritschow (1), C. Eppler, W.-D. Lehner
|
|
STC M, 52/1/2003, P.289
|
|
Keywords: Control, Drive System, Acceleration Sensor |
Abstract : The positioning features of feed drives in machine tools are nowadays
almost always guaranteed by a proportional positioning and a
proportional and integral velocity controller with an underlying fast
current controller. The achievable dynamics of the positioning control
are mainly determined by mechanical oscillations within the structure.
In this paper it is shown that the bandwidth of the positioning and
velocity controller depends also on the acquisition of the state
variables. New methods for measuring the relative acceleration according
to the Ferraris principle guarantee a velocity of low quantization
together with a conventional cascade control. Based on these
improvements it is shown that an underlying acceleration control can
increase the dynamic disturbance stiffness further. This requires new
control structures. Measuring results of single drive systems and a
milling operation with a 5-axis machine tool have shown what potential
lies in the improved acquisition of state variables by a relative
acceleration sensor to achieve highly dynamic and accurate machining
results.
|
|
Robustification of CNC Controllers for Machine Tools Motor Drives
|
|
P. Boucher (2), D. Dumur (1), P. Rodriguez
|
|
STC M, 52/1/2003, P.293
|
|
Keywords: Control, machine tool, drives |
Abstract : This paper presents a methodology for enhancing the robustness of a CNC
controlled system by convex optimisation of the Youla parameter. The
methodology requires as a first step the design of an initial polynomial
controller. This controller is then robustified considering temporal and
frequency constraints, which are formulated by means of the Youla
parameterisation within a convex optimisation framework. The optimal
Youla parameter is finally obtained by solving this optimisation
problem. In this way, a compromise between robustness and closed loop
behaviour can be easily managed. An application to the position control
of an induction motor drive is presented, where the robustness of
different controllers (PID or GPC) regarding model uncertainties in high
frequency is enhanced while respecting a temporal template for the
disturbance rejection.
|
|
Feedrate Optimization for Spline Interpolation in High Speed Machine Tools
|
|
Y. Altintas (1), K. Erkorkmaz
|
|
STC M, 52/1/2003, P.297
|
|
Keywords: Spline, CNC, Interpolator |
Abstract : A feedrate optimization technique has been developed for minimizing the
cycle time in machining spline toolpaths. Axis velocity, torque and jerk
limits are considered throughout the motion in order to ensure smooth
and linear operation of the servo drives with minimal tracking error.
Feed modulation is achieved by manipulating segment durations which
define the overall minimum jerk feed profile. Long toolpaths are handled
by applying a windowing technique. The optimized feed profile allows
nonzero acceleration and jerk values at segment connections, resulting
in continuous and smooth motion within the velocity, torque, and jerk
limits of the drives. The cycle time reduction obtained with the
proposed technique is demonstrated in high speed contouring experiments.
|
|
Sensor-less Monitoring of Cutting Force during Ultraprecision Machining
|
|
H. Shinno (2), H. Hashizume, H. Yoshioka
|
|
STC M, 52/1/2003, P.303
|
|
Keywords: Ultra-precision machining, In-process monitoring, Cutting force |
Abstract : Future ultreprecision machining systems will require intelligent machine
tools equipped with effective systems for in-process monitoring of
machining status. To meet the requirement, much attention has been
directed to the monitoring method of cutting force, temperature,
acoustic emission, etc. Cutting force includes useful information on
machining status, however it is difficult to apply these methods for an
ultraprecison machining environment. In this paper, a sensor-less
monitoring method has been proposed based on a new concept. In the
proposed method, a disturbance observer is installed in the position
controller for a linear motor-driven aerostatic table system. The
performance of the monitoring system has been evaluated through a series
of ultraprecison machining experiments.
|
|
An Optimized Design of the Bearing in Machines for Ultrasonic Machining Processes
|
|
U. Heisel (1), D. Klotz
|
|
STC M, 52/1/2003, P.307
|
|
Keywords: Ultrasonic manufacturing, bearing, vibration insulation |
Abstract : In high-power ultrasonic manufacturing processes, the design of the
bearing of the components transmitting ultrasound is of particular
importance, since the position of the nodal planes in the vibrating
structure is altering as a consequence of changing coupling conditions
during the process. A special bearing, which reduces the residual
vibrations at the fixing ring by a system of several resonators, has
been developed for the use in ultrasonic production processes, such as
tube drawing and wire drawing but also drilling and welding. Since the
transmitted longitudinal vibrations always involve radial components as
well, the dynamic stiffness of the coupling on the interface between the
components transferring energy and the components deleting vibration is
very important. In the method described in this paper, an optimization
of dynamic behavior is attained by stiffness-reduced coupling.
|
|
3- and 4-Contact Point Spindle Bearings - a new Approach for High Speed Spindle Systems
|
|
M. Weck (1), G. Spachtholz
|
|
STC M, 52/1/2003, P.311
|
|
Keywords: Spindle system, Ball bearing, High Speed |
Abstract : One important demand on spindle systems in modern machine tools is to
realise higher rotational speeds in order to increase the machining
efficiency. In conventional spindle bearings the contact angles on inner
and outer ring deviate extremely from one another with rising rotational
speeds due to centrifugal forces. Axial shift of the inner ring (elastic
mounted bearing) and increasing normal forces in the contact zones on
the outer ring are typical consequences leading to high internal bearing
loads and a reduced life span. Based on these problems bearings with a
new inner geometry are studied. Instead of two contact zones these
bearings have three or four contact zones to ensure constant contact
angles and reduced normal forces on the outer ring. In this paper
analytic operation studies and first experimental tests are presented.
|
|
A nanometre-precision, ultra-stiff piezostepper stage for ELID-grinding
|
|
H. Van Brussel (1), D. Reynaerts, p. Vanherck (1), M. Versteyhe, S. Devos
|
|
STC M, 52/1/2003, P.317
|
|
Keywords: Positioning, piezoelectric, ultra-precision |
Abstract : The extremely high machine stiffnesses required for a successful
implementation of ELectrolytic In-process Dressing (ELID) grinding
cannot be obtained with conventional technologies. In this paper, an
innovative drive concept is presented, where the actuation and guiding
functions in three degrees of freedom are combined in one functional
unit, using an original piezo-stepping technology. The stage is actively
positioned by a set of six ?feet? giving it an infinite static stiffness
in all six degrees of freedom. The drive motions in x-, y- and
C-directions are obtained by rolling the feet over the base surface in a
three-by-three feet gait pattern. The stepping resolution can be as low
as 2.5 nm. Hammering is avoided by force-controlled stepping. The x and
y stage positions are interferometrically measured. Thermal errors are
minimised by a symmetrical design.
|
|
Development of a 9 Axes Machine Tool for Bone Cutting
|
|
M. Mitsuishi (2), S. Warisawa, F. Tajima, M. Suzuki, K. Tanimoto, K. Kuramoto
|
|
STC M, 52/1/2003, P.323
|
|
Keywords: Machine Tool, CAD/CAM, Biomedical Application |
Abstract : The femur and the tibia must be shaped to ensure that they are fit
firmly to an artificial joint in total knee joint replacement. The
normal procedure is to manually cut the bones using a bone saw and
mechanical jigs. A 9 axes bone cutting machine tool has been developed
by the authors to increase cutting accuracy and reduce the hospital stay
required for recuperation. As developed, the cut plane is determined by
a 5 degree-of-freedom mechanism and the femur and tibia are cut by
moving two translational and one rotational degrees of freedom to avoid
the ligament. Preoperative planning system as a CAD/CAM system and
overview of the assisting system for total knee arthroplasty are also
discussed. Experimental results for bone cutting are presented.
|
|
Assessment of Force-Induced Errors in CNC Turning
|
|
S. Hinduja (1), D. Mladenov, M. Burdekin
|
|
STC M, 52/1/2003, P.329
|
|
Keywords: CNC turning, force-induced errors, spindle-bearing system |
Abstract : This paper describes a procedure to evaluate the force-induced errors
occurring in cylindrical turned components. This procedure is based on a
model which represents the real-time stiffness of the spindle-bearing
system and the rotational clamping stiffness of the component held in a
chuck. The stiffness values are determined from a single cutting test in
which the deflection of a test bar is measured. The model also takes
into account the stiffness of the component and toolpost. The model is
validated by comparing the predicted error in the cylindricity of a
machined bar with the measured value.
|
|
Assessing Thermally Induced Errors of Machine Tools by 3D Length Measurements
|
|
G.H.J. Florussen, F.L.M. Delbressine (2), P.H.J. Schellekens (1)
|
|
STC M, 52/1/2003, P.333
|
|
Keywords: Machine tool, Thermal error, Measuring instrument |
Abstract : A new measurement technique is proposed for the assessment of thermally
induced errors of machine tools. The basic idea is to measure changes of
length by a telescopic double ball bar (TDBB) at multiple locations in
the machine?s workspace while the machine is thermally excited. In
addition thermal machine error models are verified and optimised by
comparing measured and predicted TDBB length deviations. Validation
measurements reveal that more than 60 %37; of the thermally induced errors
can be described by the thermal machine error model proposed at any time
and at any position in the machine?s workspace
|
|
Kineto-static Optimisation of PKMs
|
|
L. Molinari-Tosatti (2), I. Fassi, G. Legnani
|
|
STC M, 52/1/2003, P.337
|
|
Keywords: Parallel Mechanism, Performance index, Isotropy. |
Abstract : One of the main drawbacks of PKMs is the non uniformity of force and
velocity transmission and stiffness characteristics in the workspace.
This non uniformity can be dramatically reduced and in some cases, but
the case of 6 dof PKMs, even eliminated using efficient kineto-static
optimization criteria in the design phase. In this paper new performance
indexes for the optimisation of 6 dof fully parallel PKMs, developed by
the authors, are presented. These indexes overcome the fact that the
Jacobian matrix J is not consistent in units and allow an independent
study of the linear and the angular behaviour of the machine. The well
known octahedron proposed by Duffy is analysed using the new indexes.
The first Italian PKM for 5 axis milling operations ? Celerius ?
developed by ITIA-CNR using an optimisation criteria based on the
presented indexes is introduced. This machine exhibits an isotropic
behaviour in the middle of its workspace and is almost isotropic in all
the other points of the useful workspace.
|
|
Workspace Enlargement for Parallel Kinematic Machines
|
|
J. Hesselbach, M. Helm / H. Kunzmann (1)
|
|
STC M, 52/1/2003, P.343
|
|
Keywords: Kinematic Design, Robot Control, Singularity |
Abstract : The paper presents an approach that allows parallel kinematic machines
to move through singular poses typically connected with them. Using this
the usable workspace of parallel kinematic machines can be significantly
increased. This compensates the main disadvantage of parallel kinematic
machines, i.e. the sometimes poor ratio of workspace to machine size.
Their main advantage, the higher structural stiffness, is maintained. To
efficiently apply this to the kinematic design of production machines,
different types of workspaces are defined. Finally a robot is presented
that passes through singular poses and shows the possibilities in
increasing machine performance by applying the presented method.
|
|
Design of a Parallel Mechanism Platform for Simulating Six Degrees-of-freedom General Motion Including Continuous 360-degree Spin
|
|
J. Kim, Y.M. Cho, F.C. Park, J.M. Lee (1)
|
|
STC M, 52/1/2003, P.347
|
|
Keywords: Parallel mechanism, Kinematic design, Motion simulation |
Abstract : This paper presents a new six degree-of-freedom parallel mechanism
platform, which can be used as a basis for general motion simulators.
The unique feature of the platform is that it enables unlimited
continuous 360-degree spin in any rotational axes plus finite X, Y, and
Z-axis translation motion. The first part of the paper deals with the
kinematic design issue of the platform including singularity avoidance
problems. The second part describes the design and development issues of
the working sample structure. It has been assembled and tested
successfully to verify the original idea of general motion simulators.
For demonstration purposes, the real motions of the platform are
synchronized with those of the real roller coaster in operation, whose
path contains several overturning pitching and rolling loops.
|
STC O |
|
Process management for engineering environments based on dynamic process modeling
|
|
R.J. Mentink, F.J.A.M. van Houten (1), H.J.J. Kals (1)
|
|
STC O, 52/1/2003, P.351
|
|
Keywords: Engineering, Process management, Information management |
Abstract : The research presented in this paper proposes a concept for dynamic
process management as part of an integrated approach to engineering
process support. The theory of information management is the starting
point for the development of a process management system based on
evolution of information content. The use of an ontology enables the
formalization of information content. Based on this ontology, transition
relations and task definitions can be instantiated. A methodology for
the generation of task networks is presented. From these networks,
process models can be derived in the form of task chains.
|
|
Design and Analysis of a Closed-Loop Single-Workstation PPC System
|
|
A.M. Ratering, N.A. Duffie (1)
|
|
STC O, 52/1/2003, P.355
|
|
Keywords: Production, Control, Analysis |
Abstract : Methods of control engineering can be integrated with methods of
production engineering to improve robustness and performance of
production systems, while making dynamic analysis tractable and
improving understanding of complex behavior. In this paper a discrete,
dynamic model of a single workstation is developed, including
characteristic equations of transfer functions that are useful in
choosing control parameter values according to desired dynamic
performance and response. Nonlinearities such as dependence of capacity
on WIP and delay in adjusting capacity due to work rules are modeled and
incorporated into the dynamic analysis. Examples are presented of
control parameter selection and resulting performance.
|
|
Project Scheduling Approach to Production Planning
|
|
A. Markus (2), J. Vancza, T. Kis, A. Kovacs
|
|
STC O, 52/1/2003, P.359
|
|
Keywords: production, planning, project |
Abstract : We suggest a novel approach to modelling and solving production planning
(PP) problems in make to order production environments. This approach
unifies the capacity and the material flow oriented aspects of PP.
Orders are modelled as projects that compete for limited resources. The
projects consist of networks of variable-intensity activities which may
require several resources at the same time. The goal is to generate
production plans that satisfy all the temporal and resource constraints
and minimize additional or external resource usage over the planning
horizon. The model is applicable at different aggregation levels of PP,
as we show with two real-life case studies. Although the capacity and
material flow aspects of PP are coupled, a special solver developed for
the project model efficiently solves problems of real-life sizes.
|
|
Modelling of Manufacturing Systems Complexity
|
|
W.H. ElMaraghy (2), R.J. Urbanic
|
|
STC O, 52/1/2003, P.363
|
|
Keywords: Product, Process, Man-Machine Systems, Manufacturing |
Abstract : This research aims at understanding the effects of human worker
attributes within the manufacturing system. The system must balance
human characteristics, needs, skills and capabilities within the
technical and business environment, in order to be effective. A model is
needed to provide insights into the sensitivities of the manufacturing
system. A methodology to systematically determine the product and
process complexity for any manufacturing environment was introduced ? a
rapid Manufacturing Complexity Assessment Tool (MCAT). The complexity
model is based on three elements: total quantity of information,
diversity of information and the information content which corresponds
to the effort to produce a feature within a product. Product and process
complexity are decoupled and treated independently in this analysis. An
example is presented to illustrate the methodology for both. The purpose
is to develop a tool that helps to identify areas of complexity that can
be simplified.
|
|
Convertibility Measures for Manufacturing Systems
|
|
V. Maier-Speredelozzi, Y. Koren (1), S.J. Hu
|
|
STC O, 52/1/2003, P.367
|
|
Keywords: Manufacturing system, Performance analysis, Convertibility |
Abstract : With increased consumer demands for a wider variety of products in
changeable, unpredicted quantities, manufacturing system responsiveness
has become increasingly important for industry competitiveness.
Manufacturers need systems that can be rapidly adjusted with regard to
both functionality and throughput capacity over the lifetime of the
system. Convertibility is defined as the capability of a system to
adjust production functionality, or change from one product to another.
End-users of manufacturing systems are struggling with the issue of how
to measure and quantify convertibility. Metrics for convertibility are
proposed in this paper so that different manufacturing systems can be
compared with respect to this area of performance. These metrics are
based on assessments of the configuration itself, and the system
components such as machines and material handling devices. Metrics for
quantifying convertibility are useful for comparing system
configurations during the early phases of design, without requiring
detailed product or process plan information.
|
|
Stochastic Optimal Capacity Management in Reconfigurable Manufacturing Systems
|
|
F.M. Asl, A.G. Ulsoy (2)
|
|
STC O, 52/1/2003, P.371
|
|
Keywords: Reconfigurable Manufacturing Systems, Capacity Management, Optimization, Feedback Control |
Abstract : This paper presents an optimal policy, based on Markov decision theory
for the capacity management problem in a firm facing stochastic market
demand. The firm implements a reconfigurable manufacturing system and
faces a delay between the times capacity changes are ordered and the
times they are delivered. Optimal policies are presented as optimal
boundaries representing the optimal capacity expansion and reduction
levels. To increase the robustness of the optimal policy to unexpected
events, the concept of feedback control is applied to address the
capacity management problem. It is shown that feedback provides
sub-optimal solutions to the capacity management problem which are more
robust under unexpected disturbances in market demand and unexpected
events.
|
|
A Systematic Approach for Ensuring the Logistic Process Reliability of Supply Chains
|
|
H-P. Wiendahl (1), G. von Cieminski, C. Begemann
|
|
STC O, 52/1/2003, P.375
|
|
Keywords: Optimisation, Production, Management |
Abstract : In the production logistics context, the process reliability of supply
chains corresponds to their ability to meet the logistic performance
expectations of customers. This ability depends on the contributions of
all supply chain members to the logistic performance of the entire
chain. The overall performance is affected by the dynamic
interrelationships between the specific logistic performances of the
separate supply chain members. Currently, however, no practical
analytical models of the logistic supply chain dynamics are available.
This paper presents an approach for modelling and analysing the logistic
interdependencies across supply chains, the understanding of which
enables supply chains to better control their process reliability.
|
|
Decision Making in Logistics: A Chaos Theory Based Analysis
|
|
S.R.T. Kumara (1), P. Ranjan, A. Surana, V. Narayanan
|
|
STC O, 52/1/2003, P.381
|
|
Keywords: Non-linear dynamics, Production, Distributed. |
Abstract : Logistics in general is a complex system. In this paper we investigate
the existence of chaos in logistics systems. Such an investigation is
necessary to use appropriate and correct methods for further analysis,
as linear systems techniques will not be useful. If a system exhibits
chaos, decision-making should consider the system characterization
parameters from a chaos theory perspective. In this paper, we consider a
non-preemptive queuing model and its extensions to the logistics domain.
A prototypical supply chain example is used and the resulting behavior
is characterized. At certain input values the behavior of the logistics
system exhibits chaos. This information is useful for further analysis
for prediction and control. The working prototype is implemented in the
DARPA Couggar agent architecture.
|
|
Using Fuzzy Multi-Agent Decision-Making in Environmentally Conscious Supplier Management
|
|
H.C. Zhang, J. Li / M.E. Merchant (1)
|
|
STC O, 52/1/2003, P.385
|
|
Keywords: Environmental Impact, Fuzzy Simulation, Multi-Criteria Decision Making |
Abstract : Abstract Integrating environmental issues into supplier management is a
challenge to manufacturers. Environmental performance is hard to
quantify and difficult to compare with other criteria such as price and
quality. This paper proposes a fuzzy multi-agent decision-making
strategy to facilitate supplier management. A fuzzy model is used to
evaluate the environmental performance of the suppliers and the life
cycle environmental impact of the purchased product. Through analyzing
manufacturer?s business strategy, combined with other decision
parameters, an optimal supplier is selected under fuzzy multi-criteria
decision analysis.
|
|
A Novel Digital Enterprise Technology Framework for the Distributed Development and Validation of Complex Products
|
|
P.G. Maropoulos (2), B.C. Rogers, p. Chapman, K.R. McKay, D.C. Bramall
|
|
STC O, 52/1/2003, P.389
|
|
Keywords: Distributed Design Manufacturing Integration, Measurement Planning |
Abstract : The development of complex products involves considerable risk in terms
of meeting target delivery dates, controlling life-cycle costs and
establishing an efficient production network. This paper describes a new
methodology for complex product design and development that utilises the
recently proposed framework of ?Digital Enterprise Technology? (DET).
The methodology involves utilising the five technical strands of DET and
in particular focuses in developing novel methods and tools for
aggregate modelling, knowledge management and laser measurement planning
to ?bridge? the gap that exists between conceptual product design and
the organisation of the corresponding manufacturing and business
operations. A pilot system has been created for simulating the
distributed development and validation of complex aerospace products.
|
|
Collaborative Production on the Basis of Object Oriented Software Engineering Principles
|
|
G. Schuh, M. Bergholz / E. Westkämper (1)
|
|
STC O, 52/1/2003, P.393
|
|
Keywords: Factory, Design, Network |
Abstract : One of the main challenges for production enterprises is succeeding in
the dynamic competitive environment with its rapidly changing
requirements. A strategy for the individual factory to cope with these
turbulent market and technological developments is to focus itself on a
specific set of competencies and capacities and to offer these within
the framework of temporary production networks which can be rapidly
configured to meet changing requirements. Therefore, the individual
factory must be able to integrate itself into temporary partnerships for
changing production tasks but at the same time retain a stable basis for
the efficient utilisation and sustainable development of its own
capacity and competence. The developed object oriented explanation model
is based on object oriented software engineering principles and
describes an approach for the initial configuration and reconfiguration
of factories within the framework of collaborative production networks.
|
|
Negotiation mechanisms for capacity allocation in distributed enterprises
|
|
M. Bruccoleri , G. Lo Nigro , F. Federico , S. Noto La Diega (1), G. Perrone (2)
|
|
STC O, 52/1/2003, P.397
|
|
Keywords: Computer aided planning, distributed manufacturing, multi-agent system |
Abstract : The paper proposes an agent based approach for the capacity allocation
in distributed enterprises, char-acterized by complex and articulated
organizations and by geographically distributed production capaci-ties
contended by many product families. In such a scenario the process of
allocating the production ca-pacity to the single customer order is one
of the major bottlenecks of the production planning activity as far as
many organizational decisional levels are involved and market turbulence
implies a continuous re-tuning of the capacity allocation plan. A high
grade of reactiveness is needed. Agent based approaches and negotiation
models, by decentralizing the decisional control and simplifying the
decision itself, make the capacity allocation process enough reactive.
Although, when the actors involved in the negotiation have different
decisional powers and different knowledge, the problem of
decentralization and specifically the design of the negotiation
mechanism become very complex. This paper proposes two negotiation
models for the capacity allocation process in distributed enterprises.
The models, rationalised by using the standard IDEF3 representation,
have been tested in the industrial environment of a primary
semicon-ductor company.
|
|
Disassembly Scheduling with Multiple Product Types
|
|
H.-J. Kim, D.-H. Lee, p. Xirouchakis, R. Züst (1)
|
|
STC O, 52/1/2003, P.403
|
|
Keywords: Disassembly, Production Planning and Scheduling, Optimization |
Abstract : We consider the problem of determining the disassembly schedules of used
products while satisfying the demand of their parts/components over a
planning horizon. The case of multiple product types with parts
commonality is considered for the objective of minimizing the sum of
setup, disassembly operation, and in-ventory holding costs. A heuristic
algorithm is proposed using the linear programming relaxation approach.
Test results of the case study on the data obtained from a disassembly
shop show that the heuristic algorithm suggested in this paper works
well for practical problems.
|
|
Grinding Wheel Management through Neuro-Fuzzy Forecasting of Dressing Cycle Time
|
|
R. Teti (2), D. D'Addona
|
|
STC O, 52/1/2003, P.407
|
|
Keywords: Tool management, Grinding Wheels, Neuro-fuzzy system |
Abstract : A multiple supplier tool management system based on reliable tool
delivery forecasting is developed for optimum tool inventory sizing. The
system is built up on the basis of historical data on tool management
comprising the series of tool shipment and delivery dates between one
manufacturing company and several external tool manufacturers in a
supply network. If historical data are highly variable due to the
incidence of uncertain but not random factors, classical time series
analysis cannot measure the imprecision deriving from events that are
neither stochastic nor casual. An alternative is given by the analysis
through intelligent computing techniques capable to deal with
deterministic events but also take into account unpredictable factors
for better results in prediction and forecast. A neuro-fuzzy system is
used in this paper to approach optimum tool inventory sizing of CBN
grinding wheels for nickel base alloy turbine blade fabrication.
|
|
Computer-Aided Planning of Laser Scanning of Complex Geometries
|
|
H. ElMaraghy (1), X. Yang
|
|
STC O, 52/1/2003, P.411
|
|
Keywords: Computer-Aided Planning, Inspection and Quality |
Abstract : A computer-aided planning method for laser scanning based on the CAD
model has been developed. It integrates three planning criteria,
visibility, accuracy, and efficiency and detects deep concave features
that would be more suitable for CMM probing. Clustering, based on the
view angle and depth of view, is used to plan an optimal scanner
placement and motion path. Simulation studies on complex auto-parts
demonstrate the effectiveness of the generated plans. The integration of
the scanning plan with CMM controls was also demonstrated. The benefits
of the CAD-based automated laser inspection planning have been demonstrated.
|
|
Designing a Turbine Blade Cooling System Using a Generalised Regression Genetic Algorithm
|
|
R. Roy, A. Tiwari, J. Corbett (1)
|
|
STC O, 52/1/2003, P.415
|
|
Keywords: Design, Optimisation, Artificial Intelligence |
Abstract : The design of a turbine blade cooling system is a multi-objective
optimisation problem involving constraints and complex interaction among
its design variables. The aim of this paper is to develop a methodology
to optimise this design using Evolutionary Computing techniques. This
paper presents Generalised Regression Genetic Algorithm (GRGA) and the
mathematical model of a real-life turbine blade cooling system. Even in
the presence of variable interaction, the methodology identifies a
number of good feasible designs from which one could be finally chosen
based on designer?s preferences. The research also demonstrates that
GRGA is capable of optimising a real-life design.
|
|
Automation of the Powder-Injection-Moulding Process for Micro-Mechanical Parts
|
|
J. Fleischer , C. Buchholz, H. Weule (1)
|
|
STC O, 52/1/2003, P.419
|
|
Keywords: Automation, Micro production, Powder Injection Moulding |
Abstract : Powder-Injection-Moulding (PIM) offers a high potential for the
fabrication of micro-mechanical parts manu-factured in wear-resistant
materials like metal or ceramics. To ensure an economic micro-PIM
production in large lot sizes and high quality, automation of the
process is a necessity. Within the field of automation research it is of
utmost importance to set up correlations between producible sizes,
microstructure geome-tries, the demoulding capability and the separation
of microstructures from sprues. The paper presents an approach of a
closed automated process chain with the focus on the demoulding,
separation and handling of fragile micro parts. The process is built up
on moulded toothed wheels with diameters of less than 1400 µm.
|
STC P |
|
Uncertainties in CMM Measurements, Control of ISO Specifications
|
|
J.M. Sprauel, J.M.. Linares, J. Bachmann, p. Bourdet (1)
|
|
STC P, 52/1/2003, P.423
|
|
Keywords: Coordinate measuring machine, Uncertainty, Statistical |
Abstract : In the scope of quality control, accurate evaluation of measurement
uncertainties is a real challenge to im-prove the use of Coordinate
Measuring Machines (CMM). In our work, a new method, based on a
statistical approach of the problem, was therefore developed, to deduce
instantaneous measurement uncertainties di-rectly from the set of
acquired coordinates. The covariance matrix of the intrinsic parameters
which charac-terize each analyzed surface is also evaluated, thus
allowing an accurate propagation of the measurement uncertainties to the
ISO specifications to be controlled. The experiments carried out in our
study illustrate this new statistical approach and demonstrate its
relevance.
|
|
A Study on the Optimal Design of Laser-based Multilateration System
|
|
G.X. Zhang (1), X.H. Li, Y.B. Lin, S.G. Liu, X.L. Liu, X.F. Li, J.B. Guo, Z.R. Qiu, S.Z. Zhao, C.Z,
|
|
STC P, 52/1/2003, P.427
|
|
Keywords: Measurement, Optimization, Flexible Coordinate Measuring System |
Abstract : A flexible coordinate measuring system based on multi-lateration with
tracking laser interferometers has been built. The problems related to
the optimal design of the system are studied. The principle of
redundancy and its application in self-calibration, error compensation,
system optimization, lost information recovery, and measuring range
extension are discussed. A new tracking system with independent drives
and a new design of the cat?s eye are proposed. The optimal arrangement
of the multi-lateration system, which is essential for improving its
accuracy, is studied in detail. All the studies combine computer
simulations and experiments.
|
|
Strain-tuning of Optical Devices with Nanometer resolution
|
|
S.G. Kim (2), C.W. Wong, Y.B. Jeon
|
|
STC P, 52/1/2003, P.431
|
|
Keywords: Optical, Nanometer resolution, Strain-tuning |
Abstract : We stretched diffractive gratings by thin-film piezoelectric actuators,
and demonstrated observable changes in grating period with sub-nanometer
resolution. Characterization of fabricated MEMS devices suggests that
strain-tuning can be widely used to make silicon optical devices
tunable. Due to the virtual absence of electro-optic and charge carrier
effects in silicon, thermo-optics has been the only means so far to
achieve tunability. Mechanical strain-tuning would provide a faster
response time, a lower power consumption and better localization of
tunability, permitting fine tuning to fabrication mismatches, and active
compensation to external disturbances. A first tunable microcavity
photonic crystal is developed with a maximum strain of 0.21%37; to achieve
12 nm tuning of the resonant wavelength for C-band optical signals.
|
|
Precision Measurement of Two-Axis Positions and Tilt Motions
|
|
W. Gao, S. Dejima, Y. Shimizu, S. Kiyono / H. Yoshikawa (1)
|
|
STC P, 52/1/2003, P.435
|
|
Keywords: Metrology, Sensor, Positioning |
Abstract : A prototype surface encoder consisting of a sinusoidal angle grid and a
two-dimensional slope sensor is developed for two-axis position
measurement. The angle grid has a three dimensional micro-structured
surface, which is a superposition of periodic sinusoidal waves in the X-
and Y-directions with spatial wavelengths of 150 µm and amplitudes of
100 nm over an area of up to 150 mm in diameter. The laser-based slope
sensor is used to read local slope profiles of the grid surface. The X-
and Y-positions together with tilt motions about the X-, Y- and Z-axes
can be detected with resolutions of 0.1 µm and 1 arc-second through
scanning a multi-spot laser beam across the grid surface at a constant
speed.
|
|
Laser Polarization State Measurement in Heterodyne Interferometry
|
|
D.J. Lorier, B.A.W.H. Knarren, S.J.A.G. Cosijns, H. Haitjema, P.H.J. Schellekens (1)
|
|
STC P, 52/1/2003, P.439
|
|
Keywords: interferometry, measurement, non-linearity errors |
Abstract : In heterodyne interferometry the accuracy is partly limited by
non-linearity errors. These errors are caused by laser polarization
state errors and errors of optical components, including alignment. In
this paper we present two independent methods to measure the actual
polarization state properties of the laser beam. Uncertainties and
differences between the methods are discussed. Measurement of a
commercially available laser source show ellipticity up to 1:170 in the
E-fields and 0,3 ° deviation of orthogonality. This may cause a
non-linearity calculated in a heterodyne interferometer of 0,6 nm.
|
|
Precision Measurement of Cutting Tools with two Matched Optical 3D-Sensors
|
|
A. Weckenmann (2), K. Nalbantic
|
|
STC P, 52/1/2003, P.443
|
|
Keywords: Metrology, Tool, Wear |
Abstract : When economically evaluating production systems, it is important to also
take the applied tools (cutting inserts, milling cutters, drills etc.)
into consideration, as their costs within the life cycle of machine
tools are higher than the costs of the actual machines. It is necessary
to look holistically at the tool and to measure in detail the geometry
of the cutting zone. To ensure this, we propose a new measurement
approach with excellent capabilities, based on the combined use of two
optical sensors. This approach can be applied to the measurement of tool
inserts, which will be the base of further applications on complex
cutting tools.
|
|
A New Method for Thread Calibration on Coordinate Measuring Machines
|
|
S. Carmignato, L. De Chiffre (1)
|
|
STC P, 52/1/2003, P.447
|
|
Keywords: Thread, Calibration, Coordinate Measuring Machine (CMM) |
Abstract : This paper presents a new method for the calibration of thread gauges on
coordinate measuring machines. The procedure involves scanning of thread
profiles using a needle-like probe, achieving traceability by
substitution of different thread portions with corresponding paths on a
calibrated sphere. The feasibility of applying the method to calibrate a
parallel thread gauge with respect to all the relevant thread parameters
was demonstrated experimentally using a precision CMM. Application of
the comparator approach as described in ISO DTS 15530-3 gave measuring
uncertainties comparable to the values from usual calibration methods on
dedicated equipment, e.g. a measuring uncertainty of 1.8 µm was achieved
for measurement of the pitch, and 2-2.5 µm for diameter measurements.
|
|
Locally Controlling Heat Flux for Preventing Micrometre-Order Deformation with Injection Molding of Miniature Products
|
|
M. Nakao, M. Yoda, T. Nagao (1)
|
|
STC P, 52/1/2003, P.451
|
|
Keywords: miniaturization, injection molding, heat control |
Abstract : This study introduces a method of locally controlling heat flux for
preventing micrometre-order deformation with injection molding of
miniature products. The experiment used a 98?98?117 mm size mold
assembly to produce a box-shaped product of 30?15?6 mm with 1 mm thick
walls. The mold had heat flux sensors with thermocouples embedded at
depths of 0.3 mm and 0.6 mm from the surface, a sensor to measure the
pressure on the ?1 mm ejecting pin, ?1 mm double wall pipe coolers, and
?1 mm bar-shaped heaters. The mold locally controlled the heat flux for
each injection cycle or mold zone. The control improved the straightness
of the miniature product from 20 ?m to 3 ?m.
|
STC S |
|
Super Bright Light-Emitting Diode for Optical Roughness Characterization
|
|
G. Goch (2), S. Patzelt, M. Dressen
|
|
STC S, 52/1/2003, P.455
|
|
Keywords: Roughness, Optical-Measurement, Polychromatic Speckle Pattern |
Abstract : A promising in-process roughness measuring technique is based on the
detection of polychromatic scat-tered light distributions and speckle
correlation algorithms. The spectral light properties mainly influence
the measuring range and the resolution. Further approaches use lasers,
laser diodes, or a superlumi-nescent diode (SLD), to produce light beams
with a discrete or continuous spectrum and a sufficient temporal
coherence to generate speckles. The presented approach investigates the
suitability of a low-cost super bright light-emitting diode (SLED) for
roughness characterization.
|
|
Detection of machine lead in ground sealing surfaces
|
|
F. Puente Leon, N. Rau / G. Spur (1)
|
|
STC S, 52/1/2003, P.459
|
|
Keywords: Machine lead, Surface texture, Automated visual inspection |
Abstract : During the finishing of contact surfaces of rotary shaft lip type seals,
unwanted lead patterns may appear. Depending on the direction of
rotation, these spiral marks may lead to early leakage or dry run, which
may affect directly the longevity of the parts. New methods for
satisfying the high requirements of the automotive industry are
presented to determine the lead angle, the period length, and the number
of starts. In contrast to earlier approaches, with a new fusion
strategy, a robust extraction of the parameters of interest is attained
even in the case of slightly pronounced lead structures. Moreover, by
enhancing the measurement set-up with additional optical components, an
in-line inspection becomes possible.
|
|
Potentials of Different Process Kinematics in Micro Grinding
|
|
B. Denkena, T. Friemuth, M. Reichstein / H.K. Tönshoff (1)
|
|
STC S, 52/1/2003, P.463
|
|
Keywords: Grinding, Surface, Ultrasonic |
Abstract : The work described in this paper evaluates the potentials of different
process kinematics in micro grinding. First investigations in peripheral
and face grinding pointed to specific characteristics of these
processes. The machining process can be characterised by the surface
quality of the parts. Based on these results improvements for highest
surface quality and the reduction of thermal loads are developed. One
possibility to minimize the influence of the micro geometry of the
grinding tool is the application of ultrasonic grinding. By using an
ultra precision machine tool and fine grained grinding wheels high
surface qualities can be achieved.
|
|
Improvement of Mechanical Strength of Micro Tools by Controlling Surface Characteristics
|
|
H. Ohmori (2), K. Katahira, Y. Uehara, Y. Watanabe, W. Lin
|
|
STC S, 52/1/2003, P.467
|
|
Keywords: Micro tool, Surface quality, Mechanical strength |
Abstract : Micro tools require exceptionally high surface characteristics,
controllable to the nanometer level. In this research, a desk-top
machine capable of achieving excellent surface quality and machining
accuracy in micro machining was developed, and micro tools of various
shapes were prepared using the newly developed machine. The machine
successfully prepared pyramidal micro tools with tips of 2µm. The
surface of the prepared micro tools was observed closely using some
advanced instruments, and the fracture strength of the micro tools was
evaluated by indentation tests using a nano-indentation testing
instrument. These observations showed a clear and quantitative
correlation between the nanometer-level surface quality and mechanical
strength. In another test, thin metal sheets were punched using the
fabricated micro tool. The resulting holes were found to be of
exceptionally high quality.
|
|
Frictional Properties of the Micro-Textured Surface of Anisotropically Etched Silicon
|
|
N. Moronuki, Y. Furukawa (1)
|
|
STC S, 52/1/2003, P.471
|
|
Keywords: Texture, Friction, Anisotropic etching |
Abstract : Anisotropic etching of silicon produces regular shapes that consist of
{111} crystal planes. Applying a line-and-space mask pattern, textured
surfaces with periodic regular shapes such as V-grooves are easily
obtained. This paper first describes the design principle for such
textures. By choosing an appropriate crystal orientation, symmetric or
asymmetric grooves can be obtained. Variation of the texture profile is
also discussed. The frictional properties are then examined. The effects
of the texture were: (1) friction could be decreased, and (2) frictional
directionality could be obtained with a combination of asymmetric
texture and softer materials.
|
|
Optical Surface Generation of Organic Nonlinear Crystals by Single-Point Diamond Turning
|
|
Y. Namba, M. Saeki / N. Ikawa (1)
|
|
STC S, 52/1/2003, P.475
|
|
Keywords: Optical surface, Diamond turning, Organic nonlinear crystal. |
Abstract : Organic nonlinear crystals that are very soft and brittle have been
machined into optical surfaces by single-point diamond turning using
special machining conditions. The crystallographic orientations of
materials to be cut and rake angles of diamond tools strongly affect the
cutting mode. The surface roughness depends upon the cutting direction,
rake angle and nose radius of the diamond tool, feed rate and lubricant.
The surface roughness is not a factor in the depth of cut or cutting
speed. The machined surfaces of 23nm p-v in flatness and less than 1nm
rms in surface roughness were obtained.
|
|
Analysis of Tool and Workpiece Interaction in Diamond Turning
|
|
D.A. Dornfeld (1), J.F.G. Oliveira (2), D. Lee, C.M.O. Valente
|
|
STC S, 52/1/2003, P.479
|
|
Keywords: Precision turning, Monitoring, Acoustic emission |
Abstract : The surface quality obtained in diamond turning operations is highly
influenced by the interaction between the tool and workpiece. These
influences include changes in cutting forces, chip formation phenomena,
microstructure of workpiece and others. Local changes in the depth of
cut and material properties lead to variable cutting forces that may
result in unacceptable form errors. This research proposes an innovative
approach for mapping the AE RMS generated during diamond turning able to
graphically represent several features of the interaction between tool
and workpiece related to instant depth of cut distribution, grain
boundaries and grain orientation.
|
