Computer aided mould design modification and tool path regeneration for product change

COMPUTER-AIDED MOULD DESIGN MODIFICATION AND TOOL PATH REGENERATION ZHANG LIPING (B. ENG.) A THESIS SUBMITTED FOR THE DEGREE OF PHILOSOPHY DEPARTMENT OF MECHANICAL ENGINEERING NATIONAL UNIVERSITY OF SINGAPORE 2004 ACKNOWLEDGMENTS First and foremost I would like to wholeheartedly thank my supervisors, Professor Andrew Nee Yeh Ching and Associate Professor Jerry Fuh Ying Hsi for their support (morally and academically) and for giving me invaluable guidance, suggestions, encouragement and patience throughout the duration of my graduate study in National University of Singapore. I appreciate very much all they have done for me and I will gratefully remember all forever. Sincere appreciation is expressed to Associate Professor Loh Han Tong and Associate Professor Zhang Yun Feng for their kind words of advice during my research. Thanks are conveyed to National University of Singapore for providing me with the research scholarship and to Department of Mechanical Engineering and CAD/CAM/CAE Center for the use of the facilities. Finally, I wish to express my deepest thanks to some very special people in my life: my husband, Dr. Ding Xiaoming, thank to his love, patience, understanding and great support during my graduate study, for always encouraging me to my best, for never losing faith in my abilities; my son, Ding Changzhao, of his smiles, laughter and understanding; my dear parents and in-laws, for their continuous concern, confidence and moral support. This thesis is specially dedicated to them. I There are many others who have indirectly contributed to my research and although I am not mentioning any name here, I am grateful to all of them. II TABLE OF CONTENTS Acknowledgements……………………………………………………….I Table of Contents………………………………………………………III Nomenclature…………………………………………………………VIII List of Figures………………………………………………………… IX Summary…………………………………………………………… .XIII Chapter Introduction……………………………………………… .1 1.1 Product development processes…………………………………………… .3 1.2 Mould design and modification…………………………………………… .6 1.2.1 Mould structure and subsystems……………………………………… 1.2.2 Mould design………………………………………………………… .8 1.2.3 Mould design modification……………………………………………10 1.3 Tool path generation and regeneration……………………………………11 1.3.1 CNC machines and cutters…….………………………………………11 1.3.2 Tool path generation…….…………………………………………….12 1.3.3 Tool path regeneration…….………………………………………… 13 1.4 Research objectives……………………………………………….…………14 1.5 Outline of the thesis……………………………………………….……… .15 Chapter Literature Review…………………………………………17 2.1 Mould design…………………………………………………….………….18 2.1.1 Parting direction and parting line design…………………………….18 III 2.1.2 Insert design………………………………………………………….21 2.1.3 Mould system and subsystem design……………………………… 23 2.2 Tool path generation.………………………………………………………24 2.2.1 CC-point method…………………………………………………….25 2.2.2 CL-point method…………………………………………………….29 Chapter Mathematical Background of Curves and Surfaces…….34 3.1 Curve parameters………………………………………………………… 34 3.2 Surface parameters……………………………………………………… .36 3.3 Curves on surfaces…………………………………………… .………… 40 3.4 Offset surface…………………………………………………….…………41 Chapter Mould Design Modification………………………………42 4.1 Basic concepts and principles of mould design modification……… .43 4.1.1 Concepts and assumptions of mould design modification……44 4.1.2 Principles of the insert and pocket design…………………….45 4.2 Architecture of the mould design modification system………………48 4.3 Identify the solid bodies of material to be added and removed…… .50 4.4 Identify the mould insert that material needs to be added to or removed from……………………………………………………………51 4.5 Remove material from the mould…………………………………… .53 4.6 Add material to the mould…………………………………………… .53 4.6.1 Create pocket and insert……………………………………….53 4.6.2 Detect interference…………………………………………….60 4.7 Illustrative examples……………………………………………………64 IV Chapter Tool Path Regeneration with the CL-point Method……70 5.1 Terms and notations…………………………………………………….71 5.2 Basic concepts of tool path regeneration………………………………73 5.3 Methodology for detecting affected CL-points……………………… 74 5.4 Tool path regeneration algorithms for CL-point method…………….78 5.4.1 Identifying and replacing affected CL-points…………………80 5.4.2 Calculating scallop height values and adding new CL-points to the modified region……………………………………………86 5.4.2.1 Machining scallop height and step-over size………….86 5.4.2.2 Algorithm for checking the scallop height value and adding new CL-points…………………………………90 5.5 Illustrative examples…………………………………………………….93 Chapter Tool Path Regeneration with the CC-point Method….102 6.1 Terms and basic concepts…………………………………………… 103 6.2 Methodology of identifying the affected CL-points………………….104 6.3 Tool path regeneration algorithms for the CC-point method………108 6.3.1 Identifying and replacing the affected CL-points……………109 6.3.2 Adding new CL-points for the modified region…………… 116 6.3.2.1 Calculating the CL-points with the given tolerance…116 6.3.2.2 Calculating scallop height and adding new CL-points for the modified region………………………………… 119 6.3.2.3 Detecting and removing gouging CL-points……… .119 6.4 Illustrative examples………………………………………………… .119 V Chapter System Implementation and Case Studies…………… 128 7.1 The computer-aided mould design modification and tool path regeneration system…………………………………………………… 128 7.1.1 The platform…………………………………………………….128 7.1.2 The architecture of computer-aided mould design modification and tool path regeneration system………………………………… .130 7.1.3 The user interface……………………………………………….133 7.1.4 The mould design modification module……………………… .133 7.1.5 The tool path generation and regeneration module…………… 134 7.2 Case studies…………………………………………………………… .136 7.2.1 Case 1……………………………………………………………136 7.2.2 Case 2……………………………………………………………142 Chapter Conclusions and Recommendations……………………149 8.1 Conclusions……………………………………………………………….149 8.1.1 Mould design modification…………………………………… .150 8.1.2 Tool path regeneration………………………………………… 150 8.2 Recommendations……………………………………………………… 151 8.2.1 Mould design modification…………………………………… .151 8.2.2 Tool path generation…………………………………………….152 8.2.3 Tool path regeneration………………………………………… 152 List of Publications from this Study………………………………….154 VI References…………………………………………………………… .155 VII NOMENCLATURE 2D Two Dimensional 3D Three Dimensional C The Boundary of Mould Modification Region Co The Boundary of Affected CL-points CAD Computer-Aided Design CAE Computer-Aided Engineering CAM Computer-Aided Manufacturing CAD/CAM Computer-Aided Design and Manufacturing CAD/CAM/CAE Computer-Aided Design/Manufacturing/Engineering CC Cutter Contact CC-point Cutter Contact point CL-point Cutter Location point CLSF Cutter Location Source File CNC Computer Numerical Control EDM Electrical Discharge Machining EC Engineering Change MRR Metal Removal Rate UFUN User-Function UG Unigraphics VIII List of Figures Figure 1.1 Plastic part development processes…………………… ………………4 Figure 1.2 A typical injection mould structure……………………… ……………7 Figure 1.3 A general mould design process…………………………… ……… Figure 2.1 Parting lines and parting surfaces………………………………… …19 Figure 2.2 The iso-parametric method……………………………………………26 Figure 2.3 The inverse tool offset method………………………………… …….31 Figure 3.1 The Frenet frame……………………………………… …………… 35 Figure 4.1 Different shapes of inserts and pockets…………………………… …47 Figure 4.2 Framework of the mould design modification system…… ………….49 Figure 4.3 Material to be added to or removed from designed mould……………50 Figure 4.4 Cavity and core are affected by product design modification…………51 Figure 4.5 Designed insert and pocket……………………………………… … 57 Figure 4.6 An ejector hole interferes with the pocket…………………………….58 Figure 4.7 Fix the insert with screw or welding process………………………….59 Figure 4.8 Lifter and cooling holes………….……………………………………61 Figure 4.9 Minimum distance between pocket and other holes………………… 63 Figure 4.10a Old product file……………………………………………………… 65 Figure 4.10b New product file.…………………………………………………… .65 Figure 4.10c Old cavity.…………………………………………………………… 66 Figure 4.10d Modified cavity……………………………………………………… 67 Figure 4.10e Old core .…………………………………………………………… 68 Figure 4.10f Modified core………………………………………………………….69 Figure 5.1 Cutter contact (CC) and cutter location (CL) points………………… 72 IX Chapter System Implementation and Case Studies CAM functions and with the algorithm developed in this research are 61634.2 mm and 62296.1mm, respectively. Original tool paths Figure 7.9c Tool paths with replaced points and added lines before and after modification 148 CHAPTER CONCLUSIONS AND RECOMMENDATIONS 8.1 Conclusions To shorten the new product development time, the design of a new product may be changed many times during the mould design and manufacturing processes. With the existing CAD systems, the mould design cannot be modified automatically if the design parameters are lost when the part is transferred from one CAD system to another. When the mould design is changed, the tool path that covers the affected region needs to be regenerated. With the existing CAM systems, when the tool path is regenerated and error-prone in NC-machining, all the CL-points will need to be recalculated, which is very time-consuming. To solve these problems, this research has developed a computer-aided Mould Design Modification and Tool Path Regeneration System. With this system, when the design of a plastic part is changed, the mould design can be modified automatically with different methods according to the mould machining status. The tool path can then be regenerated efficiently by reusing the unaffected CL-points. New theories, methodologies and algorithms for mould design modification and tool path regeneration have been developed in this research. The system has been tested with several industrial parts. It is proven that the system can efficiently modify mould design and regenerate tool paths according to the mould machining status. The 149 Chapter Conclusions and Recommendations contributions of this research can be summarized into two areas: mould design modification and tool path regeneration, as will be discussed in the following subsections. 8.1.1 Mould design modification A new mould design modification module that can automatically modify the mould design for parametric and non-parametric parts according to the mould machining status has been developed in this research. With the developed module, the mould design modification does not rely on the product parameters that increase with the complexity of the product and the mould. Therefore, the developed module is not sensitive to the complexity of the plastic part and the designed mould. The mould design may need to be modified at different mould machining stages. Different methods have been developed to modify the mould design according to the mould machining status. When an insert needs to be designed to add extra material, the system automatically detects the interference between the pocket to be designed and the existing holes. Different pockets, inserts and fasteners can be designed based on the interference detection result. 8.1.2 Tool path regeneration New tool path regeneration algorithms have been developed in this research. With these algorithms, the affected and unaffected CL-points can be identified efficiently. The affected CL-points are then removed and replaced by new CL-points. Since the unaffected CL-points are used to machine the modified mould directly, the tool path regeneration time can be reduced greatly. 150 Chapter Conclusions and Recommendations Four propositions have been proposed and proven in the thesis for tool path regeneration. The propositions indicate two important properties of a gouge-free tool path: 1) the affected CL-points are enclosed by a boundary of CL-points that correspond to the interference-free boundary of the modified region; 2) when projected onto the XY-plane, if one CL-point is ‘before’ another, their corresponding CC-points follow the same topology. With these propositions, the affected CL-points can be efficiently identified by only noting their x- and y-values. The tool path regeneration algorithm is related to the tool path generation method. Since the tool path generation methods can be categorized into CC- and CL-point methods, two different tool path regeneration algorithms have been developed for them respectively. The tool path regeneration algorithms were implemented with the parallel tool path and CC-curve tool path generation methods. These algorithms can easily be applied to other tool path generation methods. 8.2 Recommendations The system developed in this research has solved some of the mould design modification and tool path regeneration problems. However, it does not cover all aspects in these areas, more research is needed in mould design modification, tool path generation and regeneration, as will be discussed in the following subsection. 8.2.1 Mould design modification This research emphasizes on modifying the mould design for the core and cavity. Sometimes, the change of the plastic part design may affect the parting line and the parting surfaces. More research is needed to develop algorithms that can efficiently 151 Chapter Conclusions and Recommendations and optimally identify the parting line for the modified profile based on the given parting direction and the unaffected parting lines. The plastic design modification may also lead to new undercuts. More research is needed to develop algorithms to automatically and optimally design sliders and lifters based on the given parting direction and the designed mould structures. When an insert is to be created, the optimal design of the insert which affects the quality of the moulded plastic part least is also an issue to be studied further. 8.2.2 Tool path generation With the existing algorithms, when a tool path row is to be planned, the maximum scallop height value for this row needs to be identified point by point. A challenging problem is how to identify the point with maximum scallop height value from the surface and the CC-curve information directly. This can be applied to generating tool paths efficiently and selecting cutters more accurately without generating the tool paths. 8.2.3 Tool path regeneration With the system developed in this research, as it is assumed that the original tool path has been developed by other systems (e.g., the commercial CAM software), the user needs to input the original machining parameters before the tool path can be regenerated. If these parameters can be stored in the original tool path file when it is generated, these parameters can be retrieved directly from the file, which will reduce the tool path regeneration errors caused by user input. 152 Chapter Conclusions and Recommendations In this research, tool path regeneration was focused on 3-axis machines with ball endmills. It will even be more time consuming and error-prone to generate tool paths for 4-axis and 5-axis CNC machines. More research is needed to develop algorithms that can efficiently identify and replace the affected CC-points from the generated CLpoints for them. Flat and fillet end-mills are also used in tool path generation for mould machining, especially for rough machining. New algorithms need to be developed to identify and replace the affected CL-points for these types of cutters. 153 RELATED PUBLICATIONS 1. Zhang, L. P., Fuh, J.Y.H. and Nee, A.Y. C. “Tool path regeneration for mold modification.” Computer-Aided Design, 35(9), pp.813-823, 2003. 2. Zhang, L. P., Fuh, J.Y.H. and Nee, A.Y. C. “A Tool Path Re-Generation Algorithm For Die & Mold Machining”. Proceedings of the 10th International Manufacturing Conference, Oct. 2002, Xiamen, China, Panel1-205. 3. Zhang, L. P., Nee, A.Y. C. and Fuh, J.Y.H. “An efficient CC-curve tool path regeneration algorithm for sculptured surface machining”, Journal of Engineering Manufacture, Proceedings of IMechE, Part B，218, pp. 389-402, 2004. 4. “Computer-aided mould design modification for product design change”, to be submitted to International Journal of Production Design. 154 REFERENCES [Bedi 1997] Bedi, S., Gravelle, S. and Chen, Y. H., “Principal curvature alignment technique for machining complex surfaces”, Transactions of the ASME, 119, pp.756765, 1997. [Bobrow 1985] Bobrow, J. E., “NC machine tool path generation from CSG part representations”, Computer- Aided Design, 17, pp.69-76, 1985. [Broomhead 1986] Broomhead, P. and Edkins, M., “Generating NC data at the machine tool for the manufacture of free-form surfaces”, International Journal of Production Research, 24(1), pp.1-14, 1986. [Chan 2003] Chan, W. M., Yan, L., Xiang, W. and Cheok, B. T., “A 3D CAD knowledge-based assisted injection mould design system”, International Journal of Advanced Manufacturing Technology, 22, pp.387–395, 2003. [Chen 1993] Chen, L.L., Chou, S., Y. and Woo, T. C., “Parting directions for mold and die design”, Computer-Aided Design, 25, pp.762-768, 1993. [Chen 1995] Chen, L. L., Chou, S. Y. and Woo, T. C., “Partial visibility for selecting a parting direction in mold and die design”, Journal of Manufacturing Systems, 14(5), pp.319–30, 1995. 155 References [Chin 1996] Chin, K. S. and Wong, T. N., “Knowledge-based evaluation for the conceptual design development of injection molding parts”, Engineering Applications of Artificial Intelligence, 9(4), pp.359-376, 1996. [Choi 1988] Choi, B. K., Lee, C. S., Hwang, J. S. and Jun, C. S., “Compound surface modelling and machining”, Computer-Aided Design, 20(3), pp.127-136, 1988. [Choi 1989] Choi, B. K. and Jun, C. S. “Ball-end cutter interference avoidance in NC machining of sculptured surfaces”, Computer-Aided Design, 21, pp.371-378, 1989. [Choi 1997] Choi, B. K., Kim, D. H., and Jerard, R. B., "C-space approach to tool path generation for die and mould machining", Computer-Aided Design, 29, pp.657-669, 1997. [Choi 1998] Choi, B. K. and Jerard, R. B., “Sculptured surface machining”, Kluwer Academic, The Netherlands, 1998. [Ding 2001] Ding, X. M., Fuh, J. Y. H., Lee, K. S. “Interference detection for 3-axis mold machining”, Computer-Aided Design, 33, pp.561-569, 2001. [Elber 1994] Elber, G. and Cohen, E., “Toolpath generation for freeform surface models”, Computer-Aided Design, 26 (6), pp.490–496, 1994. [Faux 1979] Faux, I. D. and Pratt, M. J., “Computational geometry for design and manufacture”, Halsted Press, New York, 1979. 156 References [Glaeser 1999] Glaeser, G., Wallner, J., Pottmann, H., “Collision-free 3-axis milling and selection of cutting tools”, Computer-Aided Design, 31, pp.225-232, 1999. [Hosaka 1992] Hosaka, M., “Modeling of Curves and Surfaces in CAD/CAM”, Springer-Verlag, New York, 1992. [Huang 1994] Huang, Y. and Oliver, J. H., “Non-constant parameter NC tool path generation on sculptured surfaces”, International Journal of Advanced Manufacturing Technology, 9, pp.281-290, 1994. [Huang 1996] Huang, Y. S., Webster, P. D. and Dean, T. A., “An image detection approach to NC rough-cut milling from solid models”, International Journal of Machine Tools and Manufacturing, 36, pp.1321-1333, 1996. [Hui 1992] Hui, K.C. and Tan, S., “Mold design with sweep operation –a heuristic search approach”, Computer-Aided Design, 24, pp.81-91, 1992. [Hwang 1992] Hwang, J. S., "Interference-free tool-path generation in the NC machining of parametric compound surfaces", Computer-Aided Design, 24, pp.667676, 1992. [Jensen 1993] Jensen, C. G. and Anderson, D. C., “Accurate tool placement and orientation for finish surface machining”, Journal of Design and Manufacturing, 3, pp.251-261, 1993. 157 References [Jun 2002] Jun, C. S., Kim, D. S. and Park, S., “A new curve-based approach to polyhedral machining”, Computer-Aided Design, 34 (5), pp.379-389, 2002. [Kim 1995] Kim, K. I. and Kim, K., "A new machine strategy for sculptured surfaces using offset surface", International Journal of Production Research, 33, pp.1683-1697, 1995. [Kruth 1997] Kruth, J. P., Willems, R. and Lecluse, D., “A design support system using high level mould objects”, CIRP International Conference and Exhibition on Design and Production of Dies and Moulds, pp.39-44, Turkey, 19–21 June, 1997. [Kuragano 1992] Kuragano, T., “Fresdam system for design of aesthetically pleasing free-form objects and generation of collision-free tool path”, Computer Aided Design, 24(11), pp.573-581, 1992. [Lai 1994] Lai, J. Y. and Wang, D. J., “A strategy for finish cutting path generation of compound surfaces”, Computers in Industry, 25, pp.189-209, 1994. [Lartigue 2001] Lartigue, C., Thiebaut, F. and Maekawa, T., “CNC tool path in terms of B-spline curves”, Computer-Aided Design, 33, pp.307-319, 2001. [Lee 1997] Lee, K. S., Fuh, J. Y. H, Zhang, Y. F., Nee, A. Y. C. and Li, Z., “IMOLD: an intelligent plastic injection mold design and assembly system”, Proceedings of the 4th International Conference On Die and Mould Technology, pp.30–37, Malaysia, 4–6 June 1997. 158 References [Lee 2003] Lee, E. “Contour offset approach to spiral toolpath generation with constant scallop height”, Computer-Aided Design, 35, pp.511-518, 2003. [Lin 1998] Lin, A. C. and Liu, H. T., “Automatic generation of NC cutter path from massive data points”, Computer-Aided Design, 30, pp.79-90, 1998. [Lin 2001] Lin, J. C., “From “Optimum gate design of free form injection mould using the adductive network”, International Journal of Advanced Manufacturing Technology, 17, pp.297–304, 2001. [Loney 1987] Loney, G. C. and Ozsoy, T. M., “NC machining of free form surface”, Computer-Aided Design, 1, pp.85-90, 1987. [Maekawa 1997] Maekawa, T., Cho, W. and Patrikalakis, N. M, “Computation of selfintersection of offsets of Bezier surface patches”, Journal of Mechanical Design, 119, pp.275-283, 1997. [Maeng 2003] Maeng, S. R., Baek, N. and Choi, B. K., “A Z-map update method for linearly moving tools”, Computer-Aided Design, 35(11), pp. 995-1009, 2003 [Majhi 1999] Majhi, J, Gupta, P, Janardan, R., “Computing a flattest, undercut-free parting line for a convex polyhedron, with application to mold design”, Computer Geometry, 13(4), pp.229–52, 1999. 159 References [Marciniak 1991] Marciniak, K., “Geometric modeling for numerically controlled machining”, Oxford University Press, Oxford, New York, 1991. [Mok 2001] Mok, C. K., Chin, K. S. and Ho, K. L., “An interactive knowledge-based CAD system for mould design in injection moulding processes”, International Journal of Advanced Manufacturing Technology, 17, pp.27–38, 2001. [Nee 1997] Nee, Y. C., Fu, M.W., Fuh, Y. H., Lee, K. S. and Zhang, Y. F., “Determination of optimal parting directions in plastic injection mold design”, Annals of CIRP, 46, pp.429-432, 1997. [Ong 1995] Ong, S. K., Prombanpong, S., Lee, K. S., “An object-oriented approach to computer-aided design of a plastic injection mould”, Journal of Intelligent Manufacturing, 6, pp.1–10, 1995. [Pottmann 1999] Pottmann, H., Wallner, J., Glaeser, G. and Ravani, B., “Geometric criteria for gouge-free three-axis milling of sculptured surfaces”, Transactions of the ASME, Journal of Mechanical Design, 121, pp.241-248, 1999. [Ravi 1990] Ravi, B. and Srinivasan, M. N., “Decision criteria for computer-aided parting surface design”, Computer-Aided Design, 22, pp.11-18, 1990. [Ravi 1997] Ravi, B, “Intelligent design of gating channels for casting”, Material Science Technology 13, pp.785–790, 1997. 160 References [Rosen 1994] Rosen, D. W., “Towards automated construction of mould and die design”, Proceedings ASME Computers in Engineering Conference, 1, pp.317-326, 1994. [Seiler 1997] Seiler, A., Balendran, V. and Sivayoganathan, K., “Tool interference detection and avoidance based on offset nets”, International Journal of Machine Tools and Manufacturing, 37, pp.717-722, 1997. [Shin 1993] Shin, K. H. and Lee, K., “Design of side cores of injection molds from automatic detection of interference faces”, Journal of Design and Manufacturing, 3, pp.225-236, 1993. [Suresh 1994] Suresh, K. and Yang, D. C. H., “Constant scallop-height machining of free-form surfaces”, Journal of Engineering for Industry, 116, pp.253-258, 1994. [Sarma 1997] Sarma, R. and Dutta, D., “An integrated system for NC machining of multi-patch surface”, Computer-Aided Design, 29, pp.741-750, 1997. [Takeuchi 1989] Takeuchi, Y., Sakamoto, M., Abe, Y. and Orita, R., “Development of a personal CAD/CAM system for mould manufacturing”, Annals of the CIRP, 38(1), pp.429-432, 1989. [Tang 1995] Tang, K., Cheng, C. C. and Dayan Y., “Offsetting surface boundaries and 3-axis gouge-free surface machining”, Computer-Aided Design, 27, pp.915-927, 1995. 161 References [Unigraphics 2000] Unigraphics on-line documentation, Version 17.0, UG Solutions Inc. Maryland Heights, 2000. [Wang 1996] Wang, Z., Lee, K. S. and Fuh J. Y. H., “Optimum ejector system design for plastic injection moulds”, International Journal of Computer Applications in Technology 9(4), pp.211–218, 1996. [Weinstein 1996] Weinstein, M. and Manoochehri, S., “Geometric influence of a mould part on the draw direction range and parting line locations”, Journal of Mechanical Design, 118 (1), pp.29–39, 1996. [Weinstein 1997] Weinstein, M., Manoochehri, S., “Optimum parting line design of moulded and cast parts for manufacturability”, Journal of Manufacturing Systems, 16(1), pp.1–12, 1997. [Willmore 1959] Willmore, T. J. “An Introduction to Differential Geometry”, Clarendon Press, Oxford, 1959. [Yang 1999] Yang, D. C. H. and Han, Z., “Interference detection and optimal tool selection in 3-axis NC machining of free-form surfaces”, Computer-Aided Design, 31, pp.303-315, 1999. [Ye 2001] Ye, X. G., Fuh, J. Y. H., Lee, K. S., “A hybrid method for recognition of undercut features from moulded parts”, Computer-Aided Design, 33, pp.1023–34, 2001. 162 References [You 1995] You, C. F. and Chu, C. H., “An automatic path generation method of NC rough cut machining from solid models”, Computers in Industry, 26(2), pp.161-173, 1995. [Yu 1996] Yu, D. Y., Duan, Z. C., Zhang, W. and Liu, J. N., “Flat-end cutter path generation for a sculptured surface for 3-axes NC machining”, Journal of Materials Processing Technology, 57, pp.65-69, 1996. [Yuan 1993] Yuan, Z. S., Li, D. Q., Chen, X. and Ye, X. G., “Integrated CAD/CAE/CAM system for injection moulding”, Computing & Control Engineering Journal, (6), pp.277-279, 1993. [Zhang 1997] Zhang, Y. F., Lee, K. S., Wang, Y., Fuh, J. Y. H. and Nee, A. Y. C., “Automatic slider core creation for designing slider/lifter of injection moulds”, CIRP International Conference and Exhibition on Design and Production of Dies and Moulds, pp.33–38, Turkey, 19–21 June 1997. [Zhang 2002] Zhang, Y. F., Liu, H. H. and Lee, K. S., “Automated Generation of Lifters for Injection Moulds”, International Journal of Advanced Manufacturing Technology, 19, pp.537–543, 2002. 163 [...]... curves and surfaces for mould design modification and tool path regeneration The mould design modification system is introduced in Chapter 4 The tool path regeneration algorithms for CL-point and CC-point tool path generation methods are introduced in Chapter 5 15 Chapter 1 Introduction and Chapter 6, respectively Chapter 7 presents the computer- aided mould design modification and tool path regeneration. .. tool path regeneration method is related to the tool path generation method, and the tool path methods can be categorized into CC- and CL-point methods, two different tool path regeneration algorithms are developed for them respectively From this research, a computer- aided Mould Design Modification and Tool Path Regeneration System has been developed to modify the mould design and regenerate tool paths... mould is modified, the entire tool path that covers the modified region will have to be recalculated This could take as much time as for generating a new tool path Therefore, the process of mould design modification and tool path regeneration in NC programming is still very tedious, time-consuming and error-prone This research aims at developing a Computer- Aided Mould Design Modification and Tool Path. .. work-piece after design modification …………….121 Figure 6.7d Regenerated tool paths with replaced points and added lines after design modification ……………………………………………………….122 Figure 6.7e Tool paths with added lines before and after design modification 123 Figure 6.8a Part surface of T-cover mould before design modification ……….124 Figure 6.8b Tool paths of T-cover mould before design modification ………... transferred from one format to another, and the design parameters may be lost during file transformation When the mould designer receives the plastic part, he/she will study and analyze the mould capability and then design the mould If the design of a plastic part is found to be not suitable for moulding, it will be returned to the product designer for modification When the mould is designed, the material... this research is to develop a mould design modification and tool path regeneration system that can solve the above two problems This research will focus on the following two issues: (1) Mould design modification Develop a mould design modification system that 14 Chapter 1 Introduction can automatically and efficiently modify a mould design based on the designed mould and the mould machining status The... 6.8c Part surface of T-cover mould after design modification …………125 Figure 6.8d Regenerated tool paths with replaced points after design modification ……………………………………………………….126 Figure 6.8e Tool paths of T-cover before and after design modification ………127 Figure 7.1 Framework of the mould modification and tool path regeneration system……………………………………………………………… 131 Figure 7.2 New product selection………………………………………………... the CAM department 1.2.3 Mould design modification When the design of a plastic part is changed, the mould design will need to be modified Since a mould has been designed and some mould inserts may have been machined, the mould design modification method is different from the mould design method Besides the geometrical and functional constraints, the structure of the designed mould also needs to be considered... work-piece after modification ………………………94 Figure 5.12d Regenerated tool paths with replaced points and added lines after modification …………………………………………….………… 95 Figure 5.12e Tool paths before and after modification with replaced points and added lines……………………………………………… ………………….96 Figure 5.13a Part surface of bezel mould before modification ………………… 98 Figure 5.13b Tool paths of bezel mould before modification …………………….98... a design tool in most mould manufacturing companies Several mould design systems have been developed to automate some of the mould design processes and shorten the design time Figure 1.3 shows a general mould design process: Upon receiving the design of the 8 Chapter 1 Designed product model Introduction Shrinkage Determine parting direction and parting line Select the mould type and mould machine Design . of T-cover mould before design modification ……….124 Figure 6.8b Tool paths of T-cover mould before design modification ……… 124 Figure 6.8c Part surface of T-cover mould after design modification …………125. developed for them respectively. From this research, a computer-aided Mould Design Modification and Tool Path Regeneration System has been developed to modify the mould design and regenerate tool. Since the tool path regeneration method is related to the tool path generation method, and the tool path methods can be categorized into CC- and CL-point methods, two different tool path regeneration