1, the distance between the shape and the edge of the hole is less than the thickness of the plate punching, the inner diameter is greater than half the outer diameter, the height is more than 1.5 times the inner diameter of the punching, the cold heading processing effect is better. Due to the close distance between the shape and the edge of the inner hole, the force of the punching needle will affect the shape, and the size of the shape will also change. In order to prevent changes in the shape size, this part of the shape must be constrained. Due to the effect of binding force, the stamping part is in a state of compressive stress, in this state of punching pressure stress, take the appropriate gap can get all bright belt stamping effect.
2, cutting extrusion forming usually, the forming of the bolt head using cold heading plastic processing, cold heading forming process than the expansion process has more advantages. Before cold heading forming, the blank must be shaped, and the blank meeting the process requirements can be obtained by shaping. The size of the blank must be paid attention to, the shape of the blank before extrusion should be determined according to the situation of the part, and the shape of the blank that is conducive to the flow of the material should be used. If the blank size is too large, that is, the cutting and extrusion margin is too large, the required cutting and extrusion force is larger, which is easy to reduce the life of the cutting and extrusion die, increase the possibility of accidental damage to the die, and consume raw materials; The cutting and extrusion allowance is too small, the corners of the parts are easy to fall off after cutting and extrusion, the shape is incomplete, and the appearance quality is not satisfactory. The mold structure focuses on the design and processing of the cutting and extrusion film, the working size of the cutting edge is best controlled in the lower limit, the Angle of the cutting and extrusion die should be suitable, the cutting edge must be ground and polished, the roughness Ra0.025 to Ra0.050μm, with the highest life. Cold heading lock manufacturers
3, drawing and forging forming with cold extrusion of the raised thick wall parts and the cup shaped parts of drawing into one, to the plate as material, using the composite forming method of drawing and compression and forming fasteners, its forming characteristics are the head of the forming and wall thickness increase.
4, local forming upsetting forming has two concepts, one is all upsetting, that is, the end face of all products have a force; The second is local upsetting pressure, that is, only the necessary part has an acting pressure. Overall forming, due to the large processing area, high forming load, the need for large tonnage punching machine, for local forming, can be used lower load to get the necessary plate thickness changes, in the hole, groove forming is widely used. ① Step parts take the joint as an example to explain the main points and applications of forming, engineering design: according to the design drawing machining - annealing - phosphorus saponification - extrusion (semi-closed extrusion and forming step). For the need of locking and chip removal, some tightening screws have 1 to 3 scraping grooving, which can be processed by cold heading processing. The most representative is the cold heading processing of the scraping grooving of automotive bolt assemblies.
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