Causes of cracks in precision stamping and bending parts and solutions ``hardware''

The cracks of precision stamping and bending parts mostly occur when the bending radius and bending angle requirements are too strict. For products with a small bending width, the cracks are at both ends of the width; when the bending width is large, the cracks occur along the bending line and near the middle of the bending width. In addition, the bending line tends to produce cracks at the right-angled portion. Solutions for cracks in precision stamping and bending parts: 1. Measures to be taken when cracks occur along the bending line. (1) When the radius of curvature is constant, the thicker the sheet, or the longer the bending width, the easier it is to produce cracks. Using SPCC type steel plate, such as R/t<0.5, cracks will occur. Therefore, R/t is designed to be 0.5 or more to avoid cracks. (2) Make the bending line at right angles to the fiber direction. However, the bending limit of the rolled material is different in the fiber direction and the vertical direction. When the bending process is close to the limit, the relationship between the bending line and the fiber direction when the sheet is blanked must be considered. (3) The burr side is placed on the inner side of the curve. (4) Remove burrs. (5) Anneal only the burr part of the curved line. (6) Compress the cut surface of the burr to a 45 degree angle, and then bend it. (7) When the bending limit of the thick plate is exceeded and it is bent to a small R, the additional back pressure method is used. In this method, in the free bending mold, the lower mold uses a strong top material plate, which can increase the compressive stress on the deformed part of the plate during the bending process, so that the bending radius can be significantly reduced and cracks can be prevented. After completing the V-shaped bending, a platform is formed on the outside of the bending radius of the product, which is caused by the back pressure of the top material. 2. Measures to be taken when cracks occur in the part of the precision stamping bending part at right angles to the bending line. (1) Move the curve back from the end face of the blank (2t+R), or align the bending line with the end face of the blank, and then make an empty groove of (1.5-2.0t+R). (2) When performing hollow bending processing, first consider punching out a groove that is 2 to 3 times larger than the plate thickness, and then bending, or opening a circular process hole in the previous process, and then punching (notching)—— Bending.