In the deep drawing process of 304 stainless steel stamping parts, wrinkling is a common and critical problem, which directly affects product quality and production efficiency. Here are some effective preventive measures against this problem.
First of all, it is crucial to properly design the shape and size of stamping parts. During the design stage, drastic shape changes and excessive drawing depths should be avoided as much as possible. For example, for some complex-shaped stamping parts, the transition fillet radius can be increased to enable the metal to flow more smoothly during the drawing process and reduce wrinkling caused by stress concentration. At the same time, the wall thickness distribution of the stretched parts is optimized to ensure uniform stress on each part during the stretching process to avoid wrinkling caused by excessive or too small local stress. For example, when designing deep cylindrical parts, the thickness of the upper part of the cylindrical wall can be appropriately increased so that it can better withstand radial tension during stretching and reduce the possibility of wrinkling.
Secondly, the correct selection and adjustment of stamping process parameters is a key link. The size of the blank holder force has a significant impact on the wrinkling phenomenon. Appropriate blank holder force can effectively inhibit the flow of metal during the stretching process and prevent excessive accumulation and formation of wrinkles. In actual operation, the optimal blank holder force value needs to be determined through experiments and experience based on the material characteristics of 304 stainless steel, the shape and size of stamping parts and other factors. In addition, the stretching speed cannot be ignored. Too high a stretching speed may cause uneven metal flow and increase the risk of wrinkling; while too low a speed will reduce production efficiency. Therefore, a moderate stretching speed should be selected to ensure that the metal can be deformed stably. For example, when deep drawing a 304 stainless steel plate with a thickness of 1 mm, the blank holder force can be controlled at 8 - 12 tons, and the drawing speed should be maintained at 10 - 20 mm/s.
Furthermore, optimizing the structure and surface quality of stamping dies is of great significance to prevent wrinkles. The gap between the punch and the concave mold of the mold should be set appropriately. A gap that is too small will increase the friction, making it difficult for the metal to flow and easily cause wrinkles; while a gap that is too large will not provide sufficient restraint. Generally speaking, the gap value can be selected between 1.1 - 1.3 times the thickness of the stainless steel plate. At the same time, the smoothness of the mold surface is improved, the friction resistance between the mold and the stainless steel plate is reduced, and the metal can flow more smoothly during the stretching process. For example, using polished molds for stamping can effectively reduce the incidence of wrinkles. In addition, some auxiliary anti-wrinkle structures, such as deep drawing ribs, can be considered in the mold design. Drawing ribs can increase the resistance of the metal to flow into the die, allowing the metal to be evenly distributed during the stretching process, thereby preventing wrinkling.
Finally, proper pretreatment of 304 stainless steel raw materials can also help reduce wrinkling. Annealing the stainless steel plate before stretching can eliminate the residual stress inside the material, improve its plastic deformation ability, and make it easier for the metal to deform evenly during the stretching process. At the same time, ensure the surface quality of the raw materials and avoid defects such as scratches and pits, because these defects will become stress concentration points during the stretching process and increase the possibility of wrinkles. For example, when purchasing raw materials, choose 304 stainless steel plates with high surface finish and good flatness, and conduct comprehensive inspection and necessary treatment before processing. Through the above preventive measures, the wrinkling phenomenon during the deep drawing process of 304 stainless steel stamping parts can be effectively reduced, and product quality and production efficiency can be improved.
