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This book is concerned with problems and solutions associated with the exchange of data between different computer aided design, engineering and manufacturing (CAx) systems. After an analysis of the current problems a new strategy consisting of a test methodology, check software and tools for the improvement of the data exchange process are discussed. The particular problems associated with the transfer of curve and surface data are expanded upon and new methods to overcome them presented. With all these tools a system-specific adaption of neutral files is made possible. Thus the integration of several incompatible CAx systems within devel- opment and production processes can be effectively improved. In order to exclude incorrect data a new methodology for neutral file processor tests has been worked out. Finally, the benefits resulting from this new strategy are shown by the example of data transfer not only between CAx systems but also between consecutive production processes.
List of contents
Project Overview.- 1 CAD/CAM data exchange in the industrial environment - methodology and tools.- 1.0 Introduction.- 1.1 Experiences with CAD data transfer.- 1.2 Problems caused by the specification.- 1.3 Problems regarding the processor quality.- 1.4 Problems caused by differences between CAD/CAM systems.- 1.5 Usage of CAD data exchange software in the industrial environment.- 1.6 Basis of neutral file adaption.- 1.7 Usage of neutral file adapting system NFAS.- 1.8 Summary.- 2 Exchange of curve and surface data.- 2.0 Introduction.- 2.1 Forms of representation.- 2.2 Exchange mechanisms.- 3 Neutral file interface requirements.- 3.0 Introduction.- 3.1 Design objectives.- 3.2 Neutral file entities.- 3.3 General parametric curve and surface representations.- 4 Conversions between representations.- 4.0 Introduction.- 4.1 Parametrisation.- 4.2 Degree elevation.- 4.3 Bézier ? explicit polynomial.- 4.4 B-spline ? Bézier.- 4.5 B-spline ? explicit polynomial.- Appendix 1 to Chapter 4.- Appendix 2 to Chapter 4.- 5 Degree reduction approximations.- 5.0 Introduction.- 5.1 Constrained Chebyshev polynomials.- 5.2 Parametric curve approximation using constrained Chebyshev polynomials.- 5.3 Surface approximation using constrained Chebyshev polynomials.- 6 More general curve and surface approximations.- 6.1 Parametric curve and surface approximation using orthogonal functions.- 6.2 Orthogonal polynomials and the least squares criterion.- 6.3 Constrained orthogonal polynomials.- 6.4 Curve approximation.- 6.5 Surface approximation.- 6.6 More general curve approximation problems.- 6.7 More general surface approximation problems.- References.- Appendix A: The neutral file check system.- A.1 The necessity of data exchange software.- A.2 The IGES tools.- A.2.1 The SYNTAX analysisprogram.- A.2.2 The POINTER analysis program.- A.2.3 The IGES check program.- A.2.4 The STATISTIC program.- A.2.5 The IGES statistic comparator program ISCOMP.- A.3 The VDAFS ANALYZER.- Appendix B: The neutral file adapting system NFAS.- B.0 Introduction.- B.1 System design.- B.1.1 NFAS control program.- B.1.2 Neutral file call interface.- B.1.3 Programming language and operating systems.- B.2 The performance of NFAS.- B.2.1 The NFAS command language.- B.2.2 The functionality of NFAS.- B.3 Implementation of NFAS.- List of Illustrations.- List of Tables.
