Shape Optimization of Clutch Drum hub Preform Using Taguchi Method

摘要

A large variety of metal forming processes is required in manufacturing for automotive applications. Traditionally the design process for metal forming tools is based on trial-and-error and on the skill of experienced die-makers. This approach results in high development cost and long lead-times. Expecially the drum clutch requires tight dimensional accuracy in its inside diameter and gear shape because it is used as the main component for the automatic transmission. The drum clutch investigated in this study is formed in 5 forming steps, which are 1st deep drawing, 2nd deep drawing, restriking, embossing, and Grob™processes. Dimensional accuracy of the final products greatly depends upon how much more accurate pre-form is manufactured in the previous forming processes before the Grob M process. The deep drawing, restriking and embossing processes in which the pre-form is formed are very important and decisive steps. Thus in some cases, excessive strain by these operations causes dimensional inaccuracy and cracks initiated from the base and wall of the product.rnBased on the above background, the objective of this study is to optimize the pre-form shape and tooling so that excessive thinning and crack formation are avoided while a sharp corner radius and flatness are obtained. Process variables such as the punch shapes both of 1st and 2nd deep drawing, and punch angle were selected to evaluate the deformation characteristics. The optimum parameters were determined from forming simulations using commercial FEM codes, F0RGE-3D and DEFORM, specifically developed for metal forming simulation. Finally, experiments for the whole drum clutch forming processes were carried out to verify the optimized forming parameters and the analytical results.