استفاده از سیستم برنامه ریزی عملیات به کمک کامپیوتر برای محصولات کشش عمیق غیرمتقارن

A computer-aided process planning system for rotationally symmetric deep drawing products has been developed. The application for non-axisymmetric components however has not been reported yet. Thus, this study investigates process sequence design and constructs a computer-aided process planning system for non-axisymmetric deep drawing products with elliptical shape. The system developed consists of three modules. The first one is three-dimensional modeling module to calculate surface area for non-axisymmetric products. The second one is a blank design module that creates an oval-shaped blank with the identical surface area. The third one is a process planning module based on production rules that play the best important roles in an expert system for manufacturing. The production rules are generated and upgraded by interviewing field engineers. Especially, drawing coefficient, punch and die radii for elliptical shape products are considered as main design parameters.

In general, deep drawing products have various cross-section shapes. For example, there is rotationally symmetric, which is so called cylindrical, square, rectangular and other non-axisymmetric shapes. Many researches have been carried out for cylindrical products that are considered as the fundamentals of deep drawing process. It is believed that empirical experiences and established production methods that are essentially based on trial-and-error procedures can make a successful production, causing substantial amounts of time, money and manpower. Recently, researches on the computer-aided process planning system for deep drawing process have been widely reported. Park et al. [1] constructed an automated process planning system for axisymmetric deep drawing products. Eshel et al. [2] developed the automatic generation of forming process outlines (AGFPO) system for axisymmetric and monotonic parts, produced by deep drawing. They suggested G&TR (generate and test, rectify) strategy for the process planning of axisymmetric deep drawing products. The system relies on experience-based die-design guidelines for its process sequence design. Altan and coworkers [3] and [4] developed a knowledge-based system in axisymmetric sheet metal. Tisza [5] presented a group technology and modularity in an expert system. The process planning systems for deep drawing process developed are mostly applications for axisymmetric products up to now, but research for non-axisymmetric products has not been reported. As the products tend to be various at production, however, shape of them will vary diversely. Therefore, it is necessary that application of process planning system for non-axisymmetric products be performed. This study makes researches of process sequence design and constructs a computer-aided process planning system for a non-axisymmetric product with an elliptical shape. The cross-section of product body consisting of a round in the major axis and a straight line in the minor one is defined as elliptical in the study. This study presents new recognition scheme, three-dimensional modeling technique, a modified Entity_List used to create three-dimensional part modeling, and accumulated production rules for non-axisymmetric products. The system was written in AutoLISP on the Auto CAD software (Release 14) environment.

This study had an eye to acquire and quantify process design variables containing drawing coefficient, punch and die radii for elliptical shape deep drawing products. This study expanded a domain of computer-aided process planning system, which definitely used in axisymmetric to non-axisymmetric products, and constructed a computer-aided process planning system. The three-dimensional modeling for non-axisymmetric products was used to calculate total surface area. And this study presents a modified Entity_List to make a part modeling for non-axisymmetric products. Oval-shaped blank was designed by use of the same area calculated in three-dimensional modeling module. Blank shape and dimension are verified by considering the experimental results composed of the appearance of the product and the flange shape for trimming. The designed blank was applied without defects in this process. Preform design is important to succeed in forming the elliptical shape deep drawing products. Therefore, drawing coefficient for preform process was suggested about 0.9 because the body consisting of a round in the major axis and a straight wall in the minor axis was formed simultaneously. The reasonable process based on industrial practice has been developed on production rules. The result of system in method II had a good agreement with the reasonable process. And user selecting the generated results enhanced flexibility of the system. Finally, it would be very useful ways to improve productivity, if various characteristics in elliptical shape deep drawing are reflected the system for the future.