Method for controlling cracking and wrinkling of deep-drawn stamping parts

The occurrence of cracking and wrinkling of deep-drawn stamping parts not only easily causes stamping parts to be scrapped in the production process, wastes raw materials, and increases production costs. The welding process is also more prone to solder joint distortion and solder joint cracking. Therefore, solving the problems of cracking and wrinkling of deep-drawn stampings is of great significance for the production of deep-drawn stampings. Based on years of practical work experience, the author summarized and analyzed the methods of controlling the cracking and wrinkling of deep-drawn metal stamping parts.

 1. Reasons for cracking and wrinkling of deep-drawn stamping parts

Specifically, the reasons for the cracking and wrinkling of deep-drawn stampings mainly include the following aspects. First, the drawing depth of the deep-drawn stamping parts is too deep, so that the sheet material flows too far in the course of the part, which leads to cracks and wrinkles. Second, it is related to the stamping jade mold. The stamping mold has a concave and convex mold, and the angle of the concave mold is large, so that the convex mold can not hold the raw material at all, so that the plate will move relative to each other during the flow process, and the stretching will not Evenly. Third, the drawing depth of deep-drawing press parts is relatively large. In the process of stamping and forming, drawbeads are rarely used or no drawbeads are used. This is mainly to ensure that there is enough blank material in the process of drawing and forming. Therefore, the blank flow of deep-drawn stamping parts is mainly controlled by the middle-pressure edge sassafras force. This leads to problems such as cracks and wrinkles in the production of deep-drawn stamping parts. Fourth, the pressure of the ejector rod is too small, resulting in incomplete forming of the stamping parts and uneven stress on the stamping parts.

  2. Measures to control the cracking and wrinkling of deep-drawn stamping parts

In general, the method of controlling the cracking and wrinkling of deep-drawn stampings is to control the flow rate of the plate. Because in the final analysis, the cracks of deep-drawn stampings are caused by too slow sheet flow during stretching, and wrinkles are caused by too fast sheet material flow during stretching.

It can be seen from this that if the sheet material is well controlled to ensure that the sheet material and the die do not move relative to each other, the section can effectively control the cracking and wrinkling of the deep-drawn copper stamping parts. Specifically, we should focus on the following aspects. Practical experience in adjusting the gap of the blanking surface has found that it is very difficult to control the blanking force. Therefore, it is necessary to adjust the stretching gap to eliminate the stress and deformation of the material due to the change in the thickness of the material. Generally speaking, adjust There are two main methods for the gap of the pressing surface. The gap between the pressing surface is tight and loose on the outside. In the straight-line bending deformation zone and the extended deformation zone of the concave die, the pressing surface is allowed to be tight inside and loose outside. Because the thickness of the plate section in these two areas is unchanged or thinner, the gap between the blanking surfaces is either larger or unchanged. Relatively speaking, the blanking force is reduced.

When the sheet material flows through the tight zone, the pressing effect of the pressing surface on the sheet is weakened. The technology frontier of the pressing surface, which is tight and loose on the outside, is discussing the method of controlling the cracking and wrinkling of deep-drawn stamping parts. The quality requirements are also getting higher and higher. As an important part of the automotive stamping process, deep-drawn stamping parts are prone to cracking and wrinkling in production practice, which seriously affects the efficiency of production. Based on this, the paper is dividing On the basis of the causes of cracking and wrinkling of the deep drawing stamping parts, it is proposed to control the cracking and cracking of the drawing stamping parts by adjusting the gap of the stinging blank, the size of the blank holder force and the corner radius of the die. Wrinkle problem.

Compression deformation occurs. With the flow of the material, the thickness of the material has a tendency to increase, which will make the gap of the blanking surface relatively reduce and increase the feed force, and the material is easy to break under the action of tensile stress. Therefore, the method of loosening inside and tightening outside should be adopted when adjusting the gap of die pressing surface to eliminate the adverse effect of material deformation on the increase of material thickness. The gap adjustment method can effectively prevent wrinkling. This principle is mainly used in the compression deformation zone, where the material is under radial tension and tangential compression. The blank is loose and tight in the gap of the blanking surface in the circumferential direction. I. Punch 2 blanking ring 3. Die 22 adjust the size of blank holder force The adjustment of blank holder force is mainly based on practical operation experience to comprehensively judge. Generally speaking, when wrinkling occurs evenly around the workpiece, the operator should pay great attention to it. This shows that the pressing force is not enough, and the wrinkling can be eliminated by gradually increasing the pressing force.

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