Analysis of the causes of deformation of aluminum alloy stamping parts

Due to the large thermal expansion coefficient of aluminum alloy stamping parts, it is easy to deform during thin-wall processing. Especially when the free forging blank is used, the machining allowance is large and the deformation problem is more prominent. There are many reasons for the deformation of aluminum alloy stamping parts, which are related to the material, the shape of the parts, the production conditions, and the performance of the cutting fluid. There are mainly the following aspects: deformation caused by internal stress of the blank, deformation caused by cutting force and cutting heat, and deformation caused by clamping force. 1. Reduce the internal stress of the blank. Natural or artificial aging and vibration treatment can partially eliminate the internal stress of the blank. Pre-processing is also an effective process method. For the blank with fat head and big ears, due to the large margin, the deformation after processing is also large. If the excess part of the blank is pre-processed and the margin of each part is reduced, not only can the processing deformation of the subsequent process be reduced, but also a part of the internal stress can be released after pre-processed for a period of time. 2. Improve the cutting ability of the tool. The material and geometric parameters of the tool have an important influence on the cutting force and cutting heat. The correct selection of the tool is very important to reduce the deformation of the parts. Reasonably select tool geometric parameters, improve tool structure, and strictly control tool wear standards. 3. Improve the clamping method of stamping parts. For thin-walled aluminum alloy workpieces with poor rigidity, the following clamping methods can be used to reduce deformation: For thin-walled bushing parts, if three-jaw self-centering chucks or spring chucks are used to clamp from the radial direction, Once loosened after processing, the workpiece will inevitably be deformed. At this time, the method of pressing the axial end face with better rigidity should be used. To locate the inner hole of the part, make a self-made threaded through mandrel, sleeve it into the inner hole of the part, press the end face with a cover plate on it, and back it with a nut. When machining the outer circle, clamping deformation can be avoided, so that satisfactory machining accuracy can be obtained. When processing thin-walled and thin-plate workpieces, it is best to choose a vacuum chuck to obtain a uniform clamping force, and then process it with a small amount of cutting, which can well prevent the deformation of the workpiece. In addition, a packing method can also be used. In order to increase the process rigidity of thin-walled workpieces, medium can be filled inside the workpiece to reduce the deformation of stamping parts during clamping and cutting. 4. Reasonable arrangement of procedures. During high-speed cutting, due to the large machining allowance and intermittent cutting, the milling process often produces vibration, which affects the machining accuracy and surface roughness. Therefore, the CNC high-speed cutting process can generally be divided into: rough machining-semi-finish machining-clear corner machining-finishing and other processes. For parts with high precision requirements, it is sometimes necessary to perform secondary semi-finishing and then finishing. After rough machining, the parts can be cooled naturally to eliminate internal stress caused by rough machining and reduce deformation. The margin left after rough machining should be greater than the amount of deformation, generally 1-2mm. During finishing, the finishing surface of the part should maintain a uniform machining allowance, generally 0.2-0.5mm is appropriate, so that the tool is in a stable state during the machining process, which can greatly reduce cutting deformation, obtain good surface machining quality, and ensure Precision of aluminum alloy stamping parts. Recommended article: Specific requirements for stamping processability of metal materials] Previous: Common quality problems of bending stamping parts and improvement countermeasures