Automotive stamping parts are mainly classified according to process, which can be divided into two categories: separation process and forming process. Separation process is also known as blanking, its purpose is to separate the stamping parts from the sheet metal along a certain contour line, and ensure the quality requirements of separation section. The purpose of forming process is to make the sheet metal plastic deformation without breaking, and to make the workpiece with the required shape and size. In the actual production, many processes are often applied to a workpiece. Blanking, bending, shearing, stretching, bulging, spinning and straightening are the main punching separation processes.
Blanking is a basic stamping process using die to separate materials. It can be directly made into flat parts or prepared for other stamping processes, such as bending, deep drawing, forming, etc. it can also be used for cutting, trimming and so on. Blanking is widely used in automobile, household appliances, electronics, instrumentation, machinery, railway, communication, chemical, light industry, textile and aerospace industries. Blanking process accounts for about 50% - 60% of the whole stamping process. Bending in forming process: the plastic forming method of bending sheet metal, pipe fittings and profiles into a certain angle, curvature and shape. Bending is one of the main processes widely used in stamping production. The bending of metal material of automobile stamping parts is essentially an elastic-plastic deformation process. After unloading, the workpiece will produce elastic recovery deformation in the direction, which is called rebound. Springback affects the accuracy of workpiece, which is the key technology in bending process.
Drawing: drawing, also known as drawing or calendering, is a kind of stamping processing method which uses the die to turn the blank plate obtained after blanking into an open hollow part. Thin wall parts with cylinder, ladder, cone, sphere, box and other irregular shapes can be made by drawing process. If combined with other stamping processes, the parts with extremely complex shape can be manufactured. In stamping production, there are many kinds of deep drawing parts. Because of the different geometric features, the position of the deformation zone, the nature of deformation, the distribution of deformation, and the stress state and distribution of each part of the billet are quite different, even essential. Therefore, the determination methods of process parameters, number of processes and sequence, and die design principles and methods are different. According to the characteristics of deformation mechanics, various deep drawing parts can be divided into four types: straight wall revolving body (cylindrical part), straight wall non revolving body (box part), curved surface revolving body (curved surface part) and curved surface non revolving body.
Stretch forming is to apply tensile force to the sheet metal through the stretch forming die, so that the sheet metal will produce uneven tensile stress and strain, and then the sheet metal and the stretch forming die joint surface will gradually expand, and the auto parts will completely fit with the stretch forming model surface. Stretch forming is mainly used to manufacture hyperbolic skin with certain plasticity, large surface area, gentle and smooth curvature change and high quality requirements (accurate shape, smooth streamline and stable quality). Because the process equipment and equipment used in stretch forming are relatively simple, the cost is low and the flexibility is large; But the material utilization and productivity are low.
Spinning is a kind of metal rotary processing technology. In the process of machining, the blank rotates with the spinning die or the spinning head rotates around the blank and the spinning die, and the spinning head moves relative to the mandrel and the blank to produce continuous local deformation of the blank and obtain the required hollow revolving parts.
Shaping is to use the given shape of the grinding tool for the secondary finishing of the product shape. Mainly reflected in the pressure plane, spring foot and so on. In view of the elasticity of some materials, when the quality of one-time forming cannot be guaranteed, the second processing is adopted.
Bulging is a processing method to obtain parts by using die to make sheet metal thin and local surface area increase. Commonly used are relief forming, cylindrical (or tubular) blank bulging and flat blank tension forming. Bulging can be realized by different methods, such as rigid die bulging, rubber bulging and hydraulic bulging.
Flanging is a kind of plastic processing method to bend the material in the edge of thin plate blank or narrow band area of preformed hole edge into vertical edge along the curve or straight line. Flanging of automobile sheet metal parts is mainly used to strengthen the edge of the parts, remove the trimming, and make the parts assembled and connected with other parts or three-dimensional parts with complex special shape and reasonable space on the parts, and improve the stiffness of the parts at the same time. In large sheet metal forming, it can also be used as a means to control cracking or wrinkling. Therefore, it is widely used in automobile, aviation, aerospace, electronics, household appliances and other industrial sectors.
Necking is a stamping method to reduce the diameter of the open end of the drawn flange free hollow part or tube blank. Before and after necking, the change of end diameter should not be too large, otherwise the end material will wrinkle due to severe compression deformation. Therefore, necking from a larger diameter to a very small diameter often requires multiple necking.