A hybrid computer-aided engineering system for process sequence design in axisymmetric sheet-metal forming.

摘要

A Computer-Aided Engineering (CAE) system for die design would result in quantifiable cost and time savings by improved standardization and could provide a permanent and confidential source of expertise.; The objective of the current research is to develop a CAE system for automatic process sequence design for the manufacture of axisymmetric sheet metal components. The input to the CAE system is the final sheet object geometry that needs to be manufactured, and the output from the system is the process sequence with intermediate object geometries. Two main components of the hybrid CAE system are a knowledge-based expert system module (symbolic module) and a process-modeling analysis module (numeric module). The knowledge-based system module first generates an initial-guess process sequence based on experience-based die design guidelines, and this process sequence is then tested for defects and failures using the analysis module. The analysis module formulates mechanics of metal forming and predicts stresses and strains in the deformed geometry and also the punch load versus the punch displacement.; The knowledge-based system consists of a permanent knowledge base, an inference engine, and a dynamic data buffer. The knowledge base was constructed based on the information obtained from literature, industrial visits, and die design workshops. The knowledge-based system was tested against several test cases found in die design handbooks and industrial brochures.; The finite-difference based analysis module, SHEET FORM, uses incremental theory and assumes that the sheet material is rigid plastic. Hill's anisotropic yield function is used to define the yield surface, and Swift's power-law equation is used to describe the hardening curve of the material. The tool-workpiece interface friction is modeled using modified Coulomb friction theory. SHEET FORM determines strain distributions, including bending correction, in the deformed workpiece at every instant by modeling the forming process as a quasi-static process. Hemispherical punch stretching and drawing, flat-bottom cylindrical punch stretching and drawing, and ellipsoidal punch stretching were simulated, and the predicted results were compared with experimental data within reasonable engineering accuracy.; The ongoing research work aims at expanding the present capabilities to include plane-strain stretching and drawing, redrawing, reverse drawing, coining, and ironing. (Abstract shortened with permission of author.)