Analysis and improvement of wrinkling and cracking of stamping parts

This article analyzes the wrinkles and cracks of the parts, describes how to solve the wrinkles and cracks of the stamping parts during the production process and the mold manufacturing and debugging stage, and how to prevent them in the product and design stages to avoid the occurrence of the parts during production. Wrinkles and cracks can improve the quality of parts, reduce the scrap rate of parts, shorten the mold debugging cycle, and improve production efficiency. With the rapid development of the automobile industry, automobile production continues to increase, and various defects in the stamping production process of automobile parts cause parts to be scrapped, which not only increases manufacturing costs, but also causes waste of raw materials. This article analyzes various defects in the production process of automobile stamping parts, and finds that the number of scrapped parts caused by wrinkling and cracking accounts for the vast majority of the total amount of scrapped parts. By solving the problems of cracking and wrinkling of the parts, you can Effectively reduce the scrap rate of parts and save production costs. Causes of wrinkling of stamping parts 1) The drawing depth of stamping parts is too deep, which causes the sheet material to flow too fast in the process of feeding, and wrinkles are formed. 2) In the drawing process of the stamping part, the concave die R angle is too large, which causes the punch to be unable to press the material during the drawing process, causing the sheet material to flow too fast and form wrinkles. 3) The pressing ribs of the stamping parts are unreasonable, the pressing ribs are too small and the position is incorrect, which cannot effectively prevent the sheet from flowing too fast and forming wrinkles. 4) If the pressure of the ejector pin is too small, the stamping part may not be formed completely, causing wrinkles. 5) The mold positioning design is unreasonable, causing the stamping parts to be unable to hold the material or the blanking edge is too small during the drawing process, resulting in the inability to hold the material during the drawing process, resulting in wrinkles. 6) The gap between the convex and concave molds is too large, which causes the material to be unable to be pressed during the stretching process, causing wrinkles. Measures to prevent wrinkling 1) Use a reasonable material pressing device. When using a material pressing device, the material pressing device tightly presses the deformed part of the blank and exerts a pressing force on it to prevent the flange part from arching. Wrinkle. The size of the pressing force should be appropriate. The pressing device is divided into two types: elastic pressing and rigid pressing. The elastic device is suitable for shallow drawing, and the rigid device is suitable for deep drawing. 2) Reasonable use of drawbeads to set drawbeads on the pressing surface is an effective and useful method to adjust and control deformation resistance. The drawbeads can well adjust the flow of the material, and the flow resistance of each part of the material during the stretching process is uniform, so that the amount of material flowing into the cavity is suitable for the needs of the part, preventing more wrinkles and less cracking The phenomenon. For curved stretched parts with complex shapes, especially stretched parts with small flanges, drawbeads should be set to increase the radial tensile stress of stretching to control wrinkles; the setting position of the drawbeads is in the radial direction. The place where the stress is small is the place where the sheet material is easy to flow. For parts with small flanges, in order to set drawbeads, some materials (process supplementary materials) can be appropriately added, and this part will be removed when trimming. For drawn parts with a large difference in drawing depth, the draw bead should be set in the part with less feed, so that too much material in this part can be pulled into the cavity of the cavity to prevent wrinkles. Reasons for cracking of metal stamping parts: 1. Excessive local tensile stress. Due to excessive local tensile stress during processing, the metal stamping parts are affected by internal stress and external impact, resulting in local large bulging deformation and cracking. 2. The forming process parameters are not executed properly. During the forming of the part, the process requires that the die, the blanking core and the two parts must be tightly fitted together. When the slide of the machine tool slides down, the sheet material is plastically deformed to achieve forming. , The processing technicians did not adjust the pressure of the machine tool in time at this stage according to the specified requirements of the process, and the work was unstable, causing the stamping parts to crack. 3. Defects in the design of the flanging forming mold. The mold is shared for the left/right parts of a mold with two cavities. Because the content of this process is not only the flanging, but also the shape forming content. In addition, the parts are particularly complex and the curved surface is narrow. The core is consistent with the forming surface, and the dual power supply results in a large forming stroke of the mold structure, a small pressing area, and cracking. Methods of preventing cracking of metal stamping parts: 1. Deep drawing process of metal stamping parts: The drawing direction should make the contact area between the punch and the blank as large as possible, and the reasonable shape of the blanking surface and the blank holder force make the resistance of each part of the blanking surface uniform and moderate. Reduce the drawing depth, open process holes and process cuts, etc. 2. Structural design of metal stamping parts: When designing, the radius of each fillet should be larger, the actual depth of the curved surface shape in the drawing direction should be shallower, the depth of each part should be uniform, the shape should be as simple as possible, and the change should be as gentle as possible. 3. Mold design of metal stamping parts: measures such as reasonable design of deepening ribs, larger mold fillets, and reasonable clearance between punch and die can be taken. During the processing of metal stamping parts, many faults and defects such as cracks will appear. These require reasonable design and careful operation by the processing factory staff in order to prevent and reduce the occurrence of defective metal stamping parts and improve product quality. 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