Stamping is a kind of production technology that with the help of the power of conventional or special stamping equipment, the sheet metal is directly deformed by deformation force in the die, so as to obtain product parts with certain shape, size and performance. It is one of the main methods of metal plastic processing. The common special stamping equipment is a punching machine, which is usually called a punch. Through this die, blanking, punching, forming, stretching, trimming, fine punching, shaping, riveting and extruding parts can be carried out. Stamping is widely used in various fields, and there are a large number of stamping parts in automobile bodies, instruments, household appliances, bicycles, office machinery, household utensils and other products. The following is a brief introduction to the common technological methods of punch processing:

(1) Bending: a plastic forming method of bending metal plates, pipes and profiles into a certain angle, curvature and shape. Bending is one of the main processes widely used in stamping parts production. The bending of metal materials is essentially an elastic-plastic deformation process. After unloading, the workpiece will produce elastic recovery deformation in the direction, which is called springback. Springback affects the accuracy of the workpiece and is the technical key that must be considered in the bending process.

(2) Drawing: Drawing, also known as drawing or calendering, is a stamping method that turns blank plates into open hollow parts with dies. Thin-walled parts with irregular shapes, such as cylinder, step, cone, sphere and box, can be manufactured by deep drawing process. If combined with other stamping processes, parts with extremely complex shapes can also be manufactured. Because of its different geometric characteristics, the position, nature and distribution of deformation zone and the stress state and distribution law of each part of blank are very different, even essentially different.

(3) Stretching: the sheet is stretched by the stretching die, which causes uneven tensile stress and strain on the sheet, and then the joint surface between the sheet and the stretching die gradually expands until it completely fits with the surface of the stretching die. The application object of stretch forming is mainly to manufacture hyperbolic skin with certain plasticity, large surface area, mild and smooth curvature change and high quality requirements. The process and equipment used in stretch forming are relatively simple, but the material utilization rate and productivity are low.

(4) Spinning: it is a metal rotary processing technology. In the process of machining, the blank actively rotates with the spinning die or the spinning head actively rotates around the blank and the spinning die, and the spinning head makes feeding movement relative to the core die and the blank, so that the blank generates continuous local deformation and the required hollow rotary parts are obtained.

(5) Shaping: it is to use the established grinding tool shape to carry out secondary dressing on the product shape. Mainly reflected in the pressing surface, spring feet and so on. In view of the elasticity of some materials, secondary processing is adopted when the quality of primary molding cannot be guaranteed.

(6) Bulging: it is a processing method that the sheet metal is stretched and thinned by a die, and the local surface area is increased to obtain parts. Commonly used are wave forming, cylindrical blank bulging and flat blank drawing forming. Bulging can be achieved by different methods, such as rigid die, rubber and hydraulic pressure.

(7) Flanging: It is a plastic processing method to bend the material in the narrow-band area of the edge of the thin plate blank or the edge of the prefabricated hole on the blank into a vertical edge along a curve or a straight line. Flanging is mainly used to strengthen the edge of parts and remove trimming, so that parts assembled and connected with other parts or three-dimensional parts have complex and special shapes and reasonable space, and at the same time improve the rigidity of parts.

(8) necking: it is a stamping method to reduce the diameter of the open end of the flangeless hollow part or tube blank after stretching. Before and after necking, the end diameter of the workpiece should not change too much, otherwise the end material will wrinkle due to severe compression deformation. Therefore, it is often necessary to shrink the neck from a larger diameter to a very small diameter.

The above is the common processing technology of punching machine. Through reasonable arrangement of working procedures, various types of stamping parts can be made.