January_2021_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | J A N U A R Y 2 0 2 1 4 0 DESIGN OPTIMIZATION Based on conclusions drawn from the defect analysis, the work plan was adjusted. To achieve better metal utili- zation, the shape of the flange groove was deepened, reducing the amount of blank metal required. In addition, the three positions of the pre-forging were adjusted (Fig. 4). With regard to the rim, the new approach minimizes the height difference between the pre-forging and final-forging of the rim, thereby reduc- ing the amount of metal flow during fi- nal forging of the spoke. For the flange, the new design ensures the correct amount of metal at the rim and reduc- es excess metal flow into the rim area during final forging. Finally, for the at- tachment face, the new design moves some of the metal from the rim area to the flange. The process steps were adjusted in accordance with the design modifi- cations and DEFORM simulation analy- sis was used to verify the effect of each change. Multiple designs were consid- ered to finalize the optimal solution. There were also problems in oth- er locations of the blank. As shown in Fig. 5, the design features a closed area in the plane of the attachment face, forming an approximate triangle. Ac- cording to long-term production experi- ence, it can be assumed that this design will produce folding defects. This exam- ple shows that any process adjustment is not confined to a certain position, but affects the entire blank. After many adjustments, the final design is shown in Fig. 6. Once the final design is imported into DEFORM for analysis, one can see that the optimized plan eliminates de- fects at the flange position as well as the tendency to form new defects at other locations (Fig. 7). During final production verifica- tion, 50 sample wheel hubs were pro- duced. Only three hubs contained significant folds and were scrapped, achieving a yield rate of 94%. Although a few of the other blanks were slight- ly folded, they could all be processed without any problems (Fig. 8). CONCLUSION Folding of the flange groove is caused by the flow of metal in differ- ent directions during forming. The flow direction of the rim is upward, while the metal flow at the flange position is downward. These two flow directions are at an angle, creating a fold. To re- duce or avoid the occurrence of groove folding, it is necessary to closely align the pre-forging and final-forging steps. The focus of the pre-forging step design is to minimize metal flow at the rim and flange position during final-forging. Be- cause forging is a complicated forming process, any local adjustment may cause defects in other locations. Simu- lation software can help eliminate de- sign errors before production begins. ~AM&P For more information: Jing Li, Qinhuangdao Discastal Xinglong Wheel Co. Ltd., Qinhuangdao 066000, Hebei, China, +8615603383770 , lijing1325285395@163.com. Selected References 1. Z. Zhang, Research on Process Characteristics and Inspection Methods of Forged Aluminum Alloy Wheels, China High-Tech Enterprises, 21:47-48, 2015. 2. A. Sun, Q. Ren, and J. Lu, Research of Faults and Inspection Method of Die Forging for Aluminum Alloy Wheel Hub, China Metalforming Equipment & Manufacturing Technology, 2: 64-66, 2013. 3. Z. Ma, Study on Closed-Die Forging Technology of Forging Aluminum Alloy Wheel, Forging & Stamping Technology, 40 (8):1-4, 2015. (a) (b) (c) (d) Fig. 7 — Analysis results of the final design using DEFORM software: (a) Flow direction is normal; (b) &(c) obvious problems with flow direction; and (d) final shape. Fig. 8 — Actual processing effect: (a) blank; and (b) finished product after processing. (a) (b)