The optimization design of pre-forming for forging automobile parts using Taguchi method based grey relational analysis

Abstract

This study used finite element analysis software DEFORM-3D to analyze the preform formability and die stress in the pre-forming process of forging automobile transmission components. The preform and die materials used are AISI- 5120 alloy steel and JIS-SKD61 mould steel, respectively. This research investigated the phenomenon of folding defects in the preform at the end of the final forging process. First, as the die shape under the pre-formed channel was designed to change, its die shape was close to the final forged hole shape. Then, three quality characteristics were optimally analyzed by the Taguchi method for pre-formed passes, namely, “maximum tensile stress of the upper die, ”“maximum stretch stress of the lower die, ” and “ the degree of filling of the preform in the die cavity.” Then, this study applied grey correlation analysis to identify the experimental parameter configuration that could achieve a balance between the three quality characteristics, as compared with the results obtained by the Taguchi method. The results show that the lower die after the design change of the pre-forming pass can indeed improve the phenomenon of folding defects in the preform. In terms of the overall experimental data, the experimental data obtained by grey correlation analysis can balance the experimental results of the Taguchi method based on the optimization of the three quality characteristics. The experimental result of this set of parameters not only obtained the maximum tensile stress value of 716.614 MPa in the upper die but also considered the degree of the preform filling and maximum tensile stress in the lower die. The two values were 102.56% and 836.843 MPa. Although these two values are not optimal, compared to the data obtained by the Taguchi method, the preform was filled completely in this case. The maximum tensile stress value of the lower die is also the lowest.