Causes and countermeasures of turning and distortion of metal stamping parts

1. Reasons for turning over and twisting during stamping. In the progressive die, the shape of the stamped part is formed by punching the remaining material around the stamping part. The main reason for the turning and distortion of the punching parts is the influence of the punching force. When punching, due to the existence of the punching gap, the material is stretched on one side of the die (the material is warped upward) and compressed on the side of the male die. When using the unloading plate, use the unloading plate to compress the material to prevent the material on the die side from warping upwards. At this time, the force of the material changes accordingly. As the discharge plate increases its pressing force, the material on the punch side is stretched (compression force tends to decrease), while the material on the concave die surface is compressed (tension force tends to decrease). The overturning of the stamping part is caused by the stretching of the material on the die surface. Therefore, when punching, pressing and compressing the material is the key point to prevent the punching from turning over and twisting. 2. Methods to restrain stamping parts from turning over and twisting (1). Reasonable mold design. In the progressive die, the arrangement of the blanking sequence may affect the forming accuracy of the stamping parts. For the blanking of small parts of stamping parts, generally a larger area of u200bu200bpunching is arranged first, and then a smaller area of u200bu200bpunching is arranged to reduce the impact of the punching force on the forming of the stamping part. (2). Hold down the material. Overcome the traditional mold design structure, open a material-containing gap on the discharge plate (that is, when the mold is closed, the discharge plate is attached to the concave mold, and the gap between the discharge plate and the concave mold where the material is contained is the material thickness t-0.03 ~0.05mm). In this way, the unloading plate moves smoothly during stamping, and the material can be compressed. The key forming part, the unloading plate must be made into a block-type structure to facilitate the solution of the wear (compression) loss of the pressing part of the unloading plate caused by long-term stamping, and the material cannot be compressed. (3). Add strong pressure function. That is to increase the size of the press part of the unloading insert (normal unloading insert thickness H+0.03mm) to increase the pressure on the material on the side of the die, so as to prevent the stamping part from turning over and twisting during punching. (4). The end of the punch edge is trimmed with a bevel or arc. This is an effective way to reduce cushioning power. By reducing the buffer cutting force, the tensile force on the material on the side of the die can be reduced, so as to achieve the effect of suppressing the turning and distortion of the stamping parts. (5). In daily mold production, care should be taken to maintain the sharpness of punching convex and concave die cutting edges. When the punching edge is worn, the tensile stress on the material will increase, and the tendency of stamping parts to turn over and twist becomes greater. (6). Unreasonable or uneven blanking clearance is also the cause of turning over and twisting of stamping parts, which needs to be overcome. 3. Handling of common specific problems in production. In daily production, you will encounter situations where the punching size is too large or too small (may exceed the specification requirements) and the size of the punch is greatly different, except for the consideration of forming convex and concave molds In addition to the design dimensions, machining accuracy and blanking clearance of the dies, the following aspects should also be considered to solve the problem. (1). When the punching edge is worn, the tensile stress on the material increases, and the tendency of the stamping parts to turn over and twist increases. When turning over, the size of the punching hole will become smaller. (2). The strong pressure on the material causes plastic deformation of the material, which will cause the punching size to become larger. When the strong pressure is reduced, the punching size will become smaller. (3). The shape of the edge of the punch edge. If the end is trimmed with a bevel or arc, the punching force is not easy to turn over and twist due to the slowing of the punching force, so the punching size will become larger. When the end of the punch is flat (no bevel or arc), the punching size will be relatively smaller. In the specific production practice, specific analysis should be made for specific problems, so as to find out the methods to solve the problems. The above mainly introduces the reasons and countermeasures of turning over and twisting of the punching parts during blanking. 4. Causes and countermeasures of turning over and twisting of stamping parts during bending (1). It is caused by the burrs of stamping parts during punching. Need to study the cutting edge, and pay attention to check whether the blanking gap is reasonable. (2). Turning, distortion and deformation of the punching parts have occurred during the punching process, resulting in poor forming after bending, which needs to be solved from the punching and unloading station. (3). It is caused by the instability of stamping parts during bending. Mainly for U-shaped and V-shaped bending. To deal with this problem, guiding the stamping parts before bending, guiding during the bending process, and pressing the material during the bending process to prevent the stamping parts from slipping during bending are the key points to solve the problem.