How to deal with wrinkling in stamping forming

Stamping forming is a very important metal plastic forming method. In the actual stamping forming production process, some product defects often appear. Wrinkling is one of the typical quality defects. So what is the best way to change it? In this article, a sophisticated technician will tell you why wrinkles occur in the stamping process, what are the hazards, and how to solve them. Wrinkles will directly affect the surface quality of the product. Sometimes the wrinkles will be ironed out by the mold, damage the workpiece or even scratch the mold, which will bring great losses to production. The cause of wrinkling is the instability in the thickness direction of the sheet caused by excessive local compressive stress. This form of instability is called compression instability. When wrinkles occur, the direction of wrinkles is perpendicular to the compressive stress, but it cannot be simply considered that any wrinkles are caused by compressive stress. There are various wrinkles generated during sheet metal stamping and forming. According to the different causes, they can be divided into material accumulation wrinkles and instability wrinkles. Material accumulation wrinkles are caused by too much material entering the cavity of the cavity. Wrinkles caused by instability; and instability wrinkles refer to wrinkles caused by the instability of the compression flange with weak constraining force in the thickness direction of the sheet and the instability of the uneven stretched part. Although wrinkling does not weaken the strength and rigidity of the part like tearing, it affects the accuracy and beauty of the part. If wrinkles occur in the intermediate process, it may also affect the normal progress of the next process. When the local compressive stress of the material is too large, it is easy to cause wrinkles, especially when the material is under the action of tension and compression. Therefore, the principle of eliminating wrinkles is to accurately predict the flow of the material and increase the wrinkles. Normal contact force, engineering practices generally include: 1. Increasing blank holder force The blank holder force can increase the flow resistance of the material into the die, and can alleviate the wrinkling of the flange edge. 2. Increase the number of drawbeads or increase the height of the drawbeads, including round, square, and draw bars, and the feed resistance will increase in turn. Which drawbead to use needs to be considered from many aspects, such as the drawing depth of the workpiece. , Material properties, product shape, etc. Reasonable setting of drawbeads, scientific control of feed resistance, change of internal stress state of materials, and adjustment of material flow direction can effectively improve wrinkle defects. 3. Modify the shape of the product and mold to absorb excess material [Recommended recommendation] Learn more: What are the methods for polishing the surface of stainless steel? Learn more: Manufacturing characteristics of automotive stamping parts molds Learn more: Points to note in the design of continuous stamping dies