Factors and solutions of stamping wrinkling

The development of stamping technology has effectively promoted the development of automobile industry, but in the process of stamping production, the common problem is stamping, which will lead to more serious consequences.

Factors affecting wrinkling of stamping parts

(1) Influence of drawing depth
The distribution of material flow resistance along the die mouth is directly related to the drawing depth. In the curve position of concave and convex, excessive stretching depth can cause uneven distribution of deformation resistance and wrinkle, which should be avoided as far as possible.

(2) Adjust the BHF.
When wrinkles are evenly generated around the parts, it should be judged that the pressing force is insufficient, and the wrinkles can be eliminated by gradually increasing the pressing force. When drawing conical parts and hemispherical parts, most of the materials are suspended at the beginning of drawing. It is easy to wrinkle the side wall, so in addition to increasing the blank holder force, we should also increase the radial tensile stress in the plate to eliminate wrinkles.

(3) The influence of the radius of concave die fillet.
The radius of the fillet of the die is too large, and the bending resistance of the blank flowing into the die through the fillet of the die is smaller. The smaller the bending resistance, the easier it is to cause wrinkling. The smaller the radius of the die is, the greater the bending resistance of bending deformation is, and it is less prone to wrinkle, but it is easy to cause cracking and galling of the parts.
It has been proved by a great deal of practical production experience that the main causes of wrinkling of stamping parts are the accumulation of materials during drawing and the excessive movement speed of local materials. When making practical solutions, we should consider adjusting the corresponding mechanism of the mold from the above aspects, which will achieve good results.

Cause analysis of wrinkling of tensile parts

There are many reasons for wrinkling in the drawing process, and the main reasons are as follows:

(1) The drawing depth of stamping parts is too deep, which leads to the sheet metal flowing too fast and wrinkling.

(2) The R-angle of the female die is too large in the drawing process of stamping parts, so that the male die can’t hold down the material during the drawing process, which causes the sheet to flow too fast and wrinkle.

(3) The pressing rib of stamping parts is unreasonable, too small and the position is incorrect, which can not effectively prevent the sheet from flowing too fast and forming wrinkles.

The wrinkle of unbonded tendons is obvious.

The effect of pressing material reinforcement is obviously improved.

(4) The pressure of the ejector pin is too small, which leads to incomplete forming of stamping parts and wrinkles.

(5) The positioning design of the die is unreasonable, which leads to that the stamping parts can’t be pressed or the pressing edge is too small, which leads to that the stamping parts can’t be pressed during the stretching process, resulting in wrinkling.

(6) The gap between the convex and concave dies is too large, which leads to the failure to press the material in the drawing process, resulting in wrinkling. Or the gap between the pressing surfaces is not suitable, resulting in the problem of “Marie Laure Gigon external tightness”.

Measures to prevent wrinkling of stamping parts

The way to prevent wrinkling is to ensure that the die can hold down the material during the drawing process of metal stamping parts and ensure a reasonable sheet metal flow speed. When stamping parts are stretched, the sheet metal flows too fast, which can cause wrinkling; On the other hand, if the sheet metal flows too slowly, the stamping parts will crack.

(1) Adopt reasonable material pressing device.

When using the material pressing device, the material pressing device tightly presses the deformed part of the blank and exerts a material pressing force on it to prevent the flange part from arching and wrinkling. The size of the pressing force should be appropriate. The material pressing device is divided into elastic material pressing and rigid material pressing. The elastic device is suitable for shallow drawing and the rigid device is suitable for deep drawing.

(2) Reasonable use of drawbead

Setting drawbead on the blank holder is an effective and practical method to adjust and control the deformation resistance. The drawbead can well adjust the flow of materials, make the flow resistance of materials in all parts uniform during the drawing process, make the amount of materials flowing into the cavity meet the needs of the parts, and prevent the phenomenon of more wrinkles and less cracks. For curved surface drawing parts with complex shapes, especially those with small flanges, drawbeads should be set to improve the radial tensile stress of drawing to control wrinkling; The setting position of drawbead is in the position where the radial tensile stress is small, that is, the position where the sheet metal is easy to flow. For parts with small flanges, in order to set drawbead, some materials (process supplementary materials) can be added appropriately, and this part will be removed when trimming. For the drawing parts with large difference in drawing depth, the drawing rib should be set at the part with less feed, so that too much material in this part can be organized to be drawn into the cavity of the female die, thus preventing wrinkling.


The above are the common causes of wrinkling in the drawing process of stamping parts, which need specific analysis in specific problems. According to the specific situation of stamping parts, find the specific reasons.


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