In this paper, the basic theory of multi-point stretching process was introduced, the process of multi-point stretching of saddle part was simulated, the generation and suppression of dimples were studied [1~3]. The results showed that dimple is specific defect in the multi-point stretching process; the dimples can be suppressed effectively by elastic cushion technology. Thicker elastic cushion is more effective to suppress dimples, but the error between formed workpiece and objective shape will get large. By adopting elastic cushion with appropriate thickness, workpiece with smooth surface can be obtained and the forming error is small.

The lateral bend forming is a new flexible forming method which bend section steel into parts with all kinds of curvature. The main principle and advantages of lateral bend forming is introduced. Mathematical model of lateral bend forming is established based on finite element method. Contact problem is treated. The law of forming force versus process parameters is analyzed by numerical simulation technology. The results shown as follows: the forming force is increased with the increment of the pressing quantity; the higher yield limit of material is, the bigger forming force is; the forming force of angle steel is bigger than sheet metal without changing other parameters.