The competition in the current automobile market is becoming more and more fierce, and consumers are not limited to a suitable price when choosing a product, but also pay more attention to the quality and quality of the car. Stamping is the first of the four major automotive processes. The quality of stamping parts not only affects the appearance of the body, but also reduces the corrosion resistance and product service life of the parts. Therefore, it is very important to control the quality defects of sheet metal stamping parts.

Common quality problems in the forming process of stamping parts mainly include defects such as wrinkling, cracking, springback, surface quality (collapse, slip, impact). The above problems account for more than 85% of the quality rectification of sheet metal stamping parts. Repeated rectification and maintenance of molds have reduced service life, sharply increased downtime, and increased production costs due to rework and even scrapping of products. Therefore, the occurrence and solutions of key defects in stamping parts are discussed. It has important practical value to improve the forming quality and production efficiency of products.

Wrinkling and stacking

Defect description: Due to the large difference between the size in the thickness direction of the sheet and the size in the plane direction, the thickness direction is unstable. When the stress in the plane direction reaches a certain level, the thickness direction becomes unstable, resulting in wrinkling.

Causes

1. The material is piled up and wrinkled, and there is too much material entering the cavity of the die, resulting in wrinkling.

1. Unstability and wrinkling: 1) The binding force in the thickness direction of the sheet is weak, which causes the compression flange to become unstable and wrinkle; 2) Uneven force is likely to occur in the uneven deep drawing part, which leads to instability and wrinkling.

1. The R angle of the part is too large, which leads to the fact that the punch cannot press the material during the drawing process, and the material flows too fast, resulting in wrinkles.

1. The setting of the pressing rib of the workpiece is unreasonable, or the pressing rib is too small, which cannot effectively prevent the material from flowing too fast.

1. If the product needs to increase the wrinkle rib, the wrinkle rib is not added, or the wrinkle rib is too small, which will cause the part to wrinkle during the deep drawing process.

1. The gap between the upper and lower dies is too large, which leads to the fact that the die cannot press the material during the drawing process of the part, resulting in wrinkles.

Solutions

1. In terms of product design: 1) Check the rationality of the original product model design; 2) Avoid the saddle shape of the product; 3) Add suction ribs to the wrinkle-prone parts of the product.

1. Stamping process: 1) Arrange the process reasonably; 2) Check the rationality of the binder surface and the drawing supplementary surface; 3) Check the rationality of the drawing blank, blank pressure, and local material flow; 4) Use inner ribs 5) Increase the pressing force, adjust the drawing bead and stamping direction, increase the forming process, the thickness of the sheet, and change the product and process shape to absorb excess materials.

1. Material: In the case of satisfying product performance, for some parts that are prone to wrinkling, materials with better formability are used.

The general method of rectifying wrinkling is to ensure that the mold can press the material during the deep drawing process to ensure a reasonable and normal material flow rate: if the material flows too fast during the deep drawing process, it may cause the part to wrinkle ; If the material flows too slowly, it may cause the parts to crack.

Conclusion

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