There are many types of products in the mold industry, among which the drawing die belongs to a type with higher technical content. Due to the following difficulties, it is difficult to stretch the mold: 1. Design and calculation; 2. Mold testing after mold design is completed. For designers, to design a reasonable stretching mold structure, they need to accumulate rich design experience.

Stamping conditions of the stretching die: Excessive blank holding force. When the edge pressing force is too large, wrinkling will not occur on the flange surface. The roughness of the anti wrinkle pressure plate surface, mold fit, gap, rp, rd, type and coating conditions of processing oil, and the distribution of the edge holding force caused by the buffer pin all affect the anti wrinkle pressure. If all of the above conditions for deep drawing are appropriate, the blank holder force will decrease and rupture will not occur before wrinkling. When the edge pressing force is too large, it is easy to determine because the flange surface will be fully illuminated.

Cracks at corresponding parts of punch shoulder: due to insufficient strength of the material, this defect will occur when the drawing load reaches the material breaking load. The defect occurs at the corresponding part (rp) of the shoulder R of the punch, which is closer to rp than the impact mark line. The impact mark line of the ruptured part can be observed and checked for the following situations, as it is different from other parts: or it can be extended; Or there are shiny parts above and below the flange; Or wrinkles may occur. In addition, there are sometimes shiny parts on the side walls. Initially, it ruptured laterally and presented as a tongue like shape.

After the workpiece is aligned and the program debugging is completed, it can enter the automatic processing stage. In the automatic machining process, the operator should monitor the cutting process to prevent abnormal cutting from causing workpiece quality problems and other accidents.
Monitoring the cutting process mainly considers the following aspects:

The arrangement of processing sequence should be considered based on the structure of the parts and the condition of the blank, as well as the need for positioning and clamping, with the focus on ensuring that the rigidity of the workpiece is not damaged. The sequence should generally follow the following principles: the CNC machining of the previous process should not affect the positioning and clamping of the next process, and if there are general machine tool machining processes interspersed in the middle, comprehensive consideration should also be given.

The division of CNC machining processes can generally be carried out according to the following methods: the centralized tool sorting method is to divide the processes according to the used tools, and use the same tool to CNC machine all the parts that can be completed. Using the second and third knives to complete other parts that they can complete. This can reduce the number of tool changes, compress the idle time, and reduce unnecessary positioning errors.