In the production of spring contact metal sheet, there are many elastic sheet parts that are easy to deform, such as common washers, friction sheets, disc springs, thin sheets, flying sheets, etc. Poor rigidity, heat dissipation difficulty, easy to clamp deformation and warping during processing, seriously affect the machining accuracy of parts. It is very important to study the heat treatment process and precise clamping technology of this kind of parts, that is to reduce the heat treatment deformation and clamping deformation of parts, reduce the influence of the deformation of parts on the final precision of parts, so as to ensure the machining accuracy of elastic film parts. During the process of production, the machining accuracy of most deformable elastic sheet parts is found to meet the design requirements, but after the disassembly, it is found that the size and tolerances of shape and position have changed greatly, and some of them even exceed the allowable range of design. The reasons are as follows: the rigidity of the deformable shrapnel parts is weak, the precision of the datum of the workpiece is not high, and the flatness is poor. The workpiece deforms due to clamping forces such as atmospheric or pressure, and the workpiece is processed in a deformed state. Although the on-site inspection showed that the size and shape tolerance of the workpiece met the design requirements, the deformation of the workpiece recovered after removal, and the size and shape tolerance of the workpiece changed greatly, so that the design requirements were exceeded. When testing another part of elastic thin plate which is easy to deform, it is found that the size and shape tolerance of the workpiece are far from the normal machining accuracy of the machine tool. This is because when cutting the workpiece, the cutting force causes the workpiece to deform, and the deformed part recovers after the cutting edge leaves. Therefore, it is an important measure to improve the machining accuracy of deformable elastic sheet parts by improving the precision of parts before finishing and reducing the clamping deformation and cutting force.
For elastic metal parts which are easy to deform, the rigidity is weak and the deformation is large. To improve the machining accuracy of parts, it is necessary to reduce the deformation of heat treatment. The design of parts to reduce heat treatment deformation should be closely combined with the process, pay attention to the restrictions of process conditions, as far as possible from the structure of parts to reduce heat treatment deformation. Experimental results show that the deformation of the elastic profile parts with an outer diameter of 350 mm and a thickness of 3 mm during heat treatment is 0.20 mm. If no deformation is used, the deformation will be greater than 1mm.
A layer of rubber with a uniform thickness of 0.5 mm is placed between the workpiece and the tool positioning surface. When the workpiece is clamping force, the rubber is compressed first, the elastic deformation of the workpiece is small, the surface of high precision can be machined, and the deformation is small after loosening. This method is suitable for high precision reference machining. In a three-point clamping mode, the workpiece is positioned and clamped by three points. When the workpiece is subjected to clamping force, because the workpiece surface is not stressed, there will be no clamping deformation, the workpiece is removed after the deformation is small. If there is a gap between the support block and the workpiece, it should be filled and rubber can be used if necessary. In production practice, if the workpiece size is large, the wall is thin, and the workpiece is deformed by the cutting force when the three points are positioned, auxiliary support can be added to solve the problem. The method of workpiece bonding positioning is to use adhesive to glue the workpiece to the positioning plate in free state.
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