Study on the forming accuracy of the three-cylinder crankshaft using a specific die with a preformed dressing

The complexity and specificity of the three-cylinder crankshaft lead to under-filling in the balance slider. Normally, way of the precision of the crankshaft is to increase the blank diameter or the bridge size of flash, which result in high forging load, low service life of die, and material utilization. Therefore, a preformed dressing is designed in the balance slider of the pre-forging die. During the pre-forging period, a dressing will be formed in the balance slider, which is used to ensure the precision of the three-cylinder crankshaft in the final forging period. First, CAD models of the die and billet are established, then which are simulated by the Deform-3D software. The forging load and die wear depth are analyzed, and the area of the balance slider is under-filling. Second, a new pre-forging die is designed with a preformed dressing by the CAD software. Third, response surface analysis (RSA) and finite element technology are combined to optimize the pre-forging die of the three-cylinder crankshaft. According to variance analysis, the preformed dressing is not a significant influence factor on the die wear depth and load. Optimized factors’ R, D, H of the pre-forging die are 19 mm, 84 mm, and 6 mm, respectively. Fourth, the flash height of the final forging die is optimized, and the balance slider is filled well, and the die wear depth is reduced. Finally, physical experiment and practice forging are carried out to verify the optimal scheme of the finite element method (FEM), and the results of the experimental and finite element have a good consistency.