Several details that are easily overlooked when designing bending molds

Bending parts are a kind of stamping parts, but because the bending parts are relatively simple, the design of the bending die is not complicated, resulting in the processing of the stamping and bending die, some details are often overlooked, (1) bending die The mold needs to design a U-shaped piece bending die with an ejector device. At the beginning of the bending, the bending punch contacts the top plate and compresses the steel plate, exerts sufficient pressing force on the steel plate, and the punch moves downward to U-fold the plate. Bending, at the end of the bending stroke, the punch and the top plate are crushed to correct the bending part, so that two corners can be bent at a time, the bottom of the workpiece is flat, and the quality is good. After bending, the part is lifted by the top plate. If there is no ejection device, the bottom of the U-shaped bending part is not flat, and it is difficult for the workpiece to be stuck in the concave mold. Therefore, the bending die cannot be without the ejection device. (2) The correction bending die needs a stroke limiting device. There are two forms of steel bending: free bending and correction bending. Compared with free bending, corrective bending causes the pressure to be concentrated on the corners, increases the deformation of the bending zone, and forces the inner metal of the bending area to produce tangential tensile strain, and the inner and outer fibers are stretched. After unloading Both have to be shortened, and the springback tendency of the inner and outer layers is opposite, so the bending springback can be reduced. Correction bending is generally at the end of the bending stroke, and the bending punch, sheet material, and top plate are in an 'upsetting' state. At this time, the correction force is very large. If the stroke of the punch is not accurately controlled, the mold may be crushed. Therefore, generally for safety reasons, a stroke limiting device should be installed on the bending die. (3) The bending die must be able to be positioned in actual production. The quality problems of the bending parts include springback, cracking and offset. In order to improve the accuracy of the bending parts, the steel plate should be accurately positioned on the mold, and the deviation of the steel plate should be overcome. It is necessary to design a reasonable positioning plate (shape positioning) or positioning pin (inner hole positioning). The principle of designing the positioning device is: First, the holes on the workpiece should be used as much as possible to locate, the positioning is simple and reliable, and it can also prevent the deviation of the steel plate. Secondly, the shape of the steel plate can be used for positioning. If the material is thin or the shape positioning is difficult, the guide pins on the top plate should be used for positioning. (4) When designing the bending die, take into account the deviation of the steel plate. In the bending process, the deviation is an important factor affecting the accuracy of the workpiece. The reason for the deviation is the asymmetric shape of the steel plate or the inconsistent fillet of the die. When the steel plate slides toward the die, the frictional resistance on both sides is not equal, resulting in deviation. Therefore, the use of a die with a blanking top plate, or the use of holes or process holes on the parts for positioning the steel plate in the die, can effectively reduce the deviation of the steel plate. When possible, the bending parts should be bent in pairs, with symmetrical shapes and balanced lateral forces, so that the movement of the steel plate is minimized. In V-shaped bending, in order to overcome the deviation when the steel plate is bent, a pressing ejector (top plate) is used in the mold. (5) The structure of the bending mold should not hinder and prevent the rotation and movement of the steel plate during the mold clamping process. The bending deformation zone is very concentrated, located at the corner of the bending, and the rest is only for rigid rotation. Therefore, the structure of the bending mold is not only To consider the deformation of the deformation zone, the rotation space of the steel plate during bending should also be considered. When designing the structure of the bending die, the steel plate cannot be hindered and prevented from moving and rotating, otherwise it will cause the workpiece to be deformed and affect the shape and dimensional accuracy of the workpiece. This is particularly important for complex shapes of multi-angle bending. Previous post: Several common mistakes in stamping processing, see if you have ever occurred