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汽车冲压工艺分析Automotive Sheet Steel.pdf

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汽车 冲压 工艺 分析 AUTOMOTIVE SHEET STEEL
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AK Steel Corporation Bethlehem Steel Corporation DaimlerChrysler Corporation Dofasco Inc. Ford Motor Company General Motors Corporation Ispat/Inland Inc. LTV Steel Company National Steel Corporation Rouge Steel Company Stelco Inc. U.S. Steel Group, a Unit of USX Corporation WCI Steel, Inc. Weirton Steel Corporation Auto/Steel Partnership This publication was prepared by: Body Systems Analysis Project Team The Auto/Steel Partnership Program 2000 Town Center, Suite 320 Southfield, Michigan 48075-1123 248.356.8511 fax http://www.a-sp.org A/SP-9030-3 0100 2M PROG Printed in U.S.A. Automotive Sheet Steel Stamping Process Variation An analysis of stamping process capability and implications for design, die tryout and process control. Auto/Steel PartnershipAutomotive Sheet Steel Stamping Process Variation: An Analysis of Stamping Process Capability and Implications for Design, Die Tryout and Process Control Auto/Steel Partnership Program Body Systems Analysis Project Team 2000 Town Center - Suite 320 Southfield, MI 48075-1123 2000Auto/Steel Partnership AK Steel Corporation Bethlehem Steel Corporation DaimlerChrysler Corporation Dofasco Inc. Ford Motor Company General Motors Corporation Ispat Inland Inc. LTV Steel Company National Steel Corporation Rouge Steel Company Stelco Inc. U. S. Steel Group, a Unit of USX Corporation WCI Steel, Inc. Weirton Steel Corporation This publication is for general information only. The material contained herein should not be used without first securing competent advice with respect to its suitability for any given application. This publication is not intended as a representation or warranty on the part of The Auto/Steel Partnership – or any other person named herein – that the information is suitable for any general or particular use, or free from infringement of any patent or patents. Anyone making use of the information assumes all liability arising from such use. This publication is intended for use by Auto/Steel Partnership members only. For more information or additional copies of this publication, please contact the Auto/Steel Partnership, 2000 Town Center, Suite 320, Southfield, MI 48075-1123 or phone: 248-945-7777, fax: 248-356-8511, web site: www.a-sp.org Copyright 2000 Auto/Steel Partnership. All Rights Reserved. iiTable of Contents Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.0 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1 Motivation for Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2 Study Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.0 Stamping Variation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1 Components of Variation Explained . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.2 Calculating Components of Variation Using ANOVA . . . . . . . . . . . . . . . . . . . . . 9 2.3 Description of the Sources of Stamping Variation . . . . . . . . . . . . . . . . . . . . . . . 13 3.0 Analysis of Stamping Variation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.1 Mean Conformance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.1.1 Benchmark Comparison - Body Side Outer and Inner Panels . . . . . 14 3.1.2 Mean Bias and Part Tolerances . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 3.1.3 Benchmark Comparison - Tryout versus Production . . . . . . . . . . . . . 18 3.1.4 Mean Bias Stability over Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 3.1.5 Impact of Shipping on Mean Bias . . . . . . . . . . . . . . . . . . . . . . . . . . 21 3.2 Stamping Process Variation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 3.2.1 Benchmark Comparison - Part-to-Part Variation . . . . . . . . . . . . . . . . 21 3.2.2 Variation Over Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 3.2.3 Impact of Shipping on Variation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 3.2.4 Components of Variation: Part-to-Part, Run-to-Run, and Begin-End of Run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 3.2.5 Steel Properties and Press Setup Control and Stamping Variation . . 27 3.2.6 Effect of Mean Shifts on Statistical Process Control Techniques . . . . 29 4.0 Tolerance Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 4.1 Tolerances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 4.2 Cp and Cpk (Pp and Ppk) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 4.3 Recommended Tolerances for Sheet Metal . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 4.4 Part Tolerances and Functional Build . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 5.0 Conclusions and Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Appendix A - Part Sketches by Company . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 iiiiv List of Figures Figure 1. Body Side Components Chosen for Company C . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Figure 2. Components of Variation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Figure 3. Potential Sources of Stamping Variation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Figure 4. Total Variation Partitioned into Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Figure 5. Body Side Outer for Company A: 12 Measurement Locations . . . . . . . . . . . . . . . . . 12 Figure 6. Histogram of Mean Values across 5 Parts for Company C . . . . . . . . . . . . . . . . . . . . 15 Figure 7. Mean Conformance: Rigid vs. Non-Rigid Panels . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Figure 8. Mean Conformance: Two-Piece Body Side Panel vs. One-Piece . . . . . . . . . . . . . . . 16 Figure 9. Correlation of Mean at Part Approval vs. Production . . . . . . . . . . . . . . . . . . . . . . . . . 19 Figure 10. Effect of Stamping Mean Shift on Body Side Assembly . . . . . . . . . . . . . . . . . . . . . . 20 Figure 11. Average Variation (Standard Deviation) by Type of Part . . . . . . . . . . . . . . . . . . . . . . 23 Figure 12. Part-to-Part Variation: Home Line Tryout Approval vs. Production, by Dimension . . . 24 Figure 13. Components of Variation for Body Side Panel at Company C and Company D . . . . . 26 Figure 14. Relationship between Press Tonnage and Mean Shift Variation ( mean shift) . . . . . 29 Figure 15. X-Bar/Range Chart vs. Individuals/ Moving Range Charts . . . . . . . . . . . . . . . . . . . . 32 Figure 16. Illustration of Cp and Cpk calculations for three scenarios . . . . . . . . . . . . . . . . . . . . 35 Figure 17. Part Sketches at Company A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Figure 18. Part Sketches at Company B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Figure 19. Part Sketches at Company C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Figure 20. Part Sketches at Company D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Figure 21. Part Sketches at Company E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Figure 22. Part Sketches at Company F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Figure 23. Part Sketches at Company G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44v List of Tables Table 1. Participating Automotive Manufacturers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Table 2. Components Studied at Each Automotive Manufacturer . . . . . . . . . . . . . . . . . . . . . . 5 Table 3. Formulae for Calculating Components of Variation . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Table 4. 36-Data Samples for a Stamping Dimension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Table 5. SPSS Output Calculations for Mean Squared Errors (all factors) . . . . . . . . . . . . . . . . 11 Table 6. SPSS Output Calculations for Mean Squared Errors without Begin-End Factor . . . . . 11 Table 7. Summary of Components of Variation Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Table 8. Variance Summary for twelve Body Side Dimensions . . . . . . . . . . . . . . . . . . . . . . . . 12 Table 9. Mean Conformance by Company . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Table 10. Mean Bias by Type of Part . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Table 11. Mean Conformance and Tolerances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Table 12. Summary of Mean bias: Tryout vs. Production - Case Study Parts . . . . . . . . . . . . . . 18 Table 13. Comparisons of the Change in Mean Bias from Tryout to Home Line . . . . . . . . . . . . 19 Table 14. Change in Mean from Home Line to Long-term Production . . . . . . . . . . . . . . . . . . . 20 Table 15. Summary of Panels Measured Before and After Shipping . . . . . . . . . . . . . . . . . . . . . 21 Table 16. Part-to-Part Variation for the Body Side Outer Panels . . . . . . . . . . . . . . . . . . . . . . . . 22 Table 17. Effect of Dimension Location on Variation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Table 18. Part-to-Part Variation: Home Line Approval vs. Production, by Company . . . . . . . . . 24 Table 19. Summary of Remeasured Data Before and After Shipping via truck . . . . . . . . . . . . . 25 Table 20. Summary of Part-to-Part and Total Variation for the Body Side Outers . . . . . . . . . . . 25 Table 21. Sources of Variation by Part for Company A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Table 22. Sources of Variation by Part for Company C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Table 23. Summary of Product and Process Variation Compliance . . . . . . . . . . . . . . . . . . . . . 28 Table 24. Summary of Mean Shift Variation across Companies . . . . . . . . . . . . . . . . . . . . . . . . 30 Table 25. Process Control Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Table 26. Effect of Stamping Mean Shifts on Assembly Variation . . . . . . . . . . . . . . . . . . . . . . . 33 Table 27. General Recommended Tolerances for Stamped Parts Based upon Process Capability . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36Preface This report is one of a series published by the Auto/Steel Partnership Body Systems Analysis Project Team on stamping and assembly variation, body measurement systems and process valida- tion. These reports provide a summary of the proj- ect research and are not intended to be all inclu- sive of the research effort. Numerous seminars and workshops have been given to individual automotive manufacturers throughout the project to aid in implementation and provide direct techni- cal support. Proprietary observations and imple- mentation details are omitted from the reports. This automotive body development report, “Stamping Process Variation: An Analysis of Stamping Process Capability and Implications for Design, Die Tryout and Process Control,“ updates ongoing research activities by the Body Systems Analysis Team and the Manufacturing Systems staff at The University of Michigan's Office for the Study of Automotive Transportation. An over-riding goal of this research is to develop new paradigms that will drive automotive body-in- white development and production towards a total optimized processing system. Previous reports described fundamental research investigating simultaneous development systems for designing, tooling and assembling bodies, and flexible body assembly. Since the inception of this research pro- gram, considerable emphasis has been focused on benchmarking key world class body develop- ment and production processes. These bench- marks created foundation elements upon which further advances could be researched and devel- oped. This report summarizes recommendations for moving toward a new “functional build“ paradigm by tightly integrating the many individual activities ranging from body design and engineering through process and tooling engineering. Revised stamping die tryout and buyoff processes receive special emphasis, as does the launch of stamping and assembly tools. The researchers are indebted to several global automotive manufacturers for their on-going dedi- cation and participation in this research. They include DaimlerChrysler Corporation, Ford Motor Company, General Motors Corporation, Nissan, NUMMI (Toyota), Opel and Renault. Each con- ducted experiments under production conditions involving hundreds of hours of effort and often requiring the commitment of many production workers and engineering personnel. Although it may be impractical to mention each one of these people individually, we do offer our sincere appre- ciation. These reports represent a culmination of several years of effort by the Body Systems Analysis Project Team. Team membership, which has evolved over the course of this project, includes: J. Aube, General Motors Corporation H. Bell, General Motors Corporation C. Butche, General Motors Corporation G. Crisp, DaimlerChrysler Corporation T. Diewald, Auto/Steel Partnership K. Goff, Jr., Ford Motor Company T. Gonzales, National Steel Corporation R. Haan, General Motors Corporation S. Johnson, DaimlerChrysler Corporation F. Keith, Ford Motor Company T. Mancewicz, General Motors Corporation J. Naysmith, Ronart Industries J. Noel, Auto/Steel Partnership P. Peterson, USX R. Pierson, General Motors Corporation R. Rekolt, DaimlerChrysler Corporation M. Rumel, Auto/Steel Partnership M. Schmidt, Atlas Tool and Die The University of Michigan Transportation Research Institute conducted much of the research and wrote the final reports. The principal research team from the Manufacturing Systems Group was: Patrick Hammett, Ph.D. (734-936-1121/pham- mett@umich.edu) Jay Baron, Ph.D. (734-764- 4704/jaybaron@umich.edu) Donald Smith, Associate Director (734-764-5262) viExecutive Summary The Auto/Steel Partnership (A/SP) is an innovative international association th
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