Theoretical analysis of cold extrusion

Theoretical analysis of cold extrusion

Cold roll forming machine supplier shares that in the process of cold extrusion, there are many influencing factors, such as extrusion pressure, materials, molds, equipment, etc., among which extrusion pressure is a major indicator. The extrusion pressure directly affects the die force and die life, which is a very important problem in the design. The die structure and shape can be optimized by means of extrusion analysis. Conventional analysis of extrusion pressure is based on some empirical formulas, but it is difficult to calculate accurately for some complex structures. With the development of computer technology and finite element theory, numerical simulation technology has been widely used in the process of forming simulation.

This paper analyzes the influencing factors of gear cold extrusion forming process, including blank shape, die structure, etc.

The theoretical analysis

It consists of blank, punch and die. Die can be divided into two parts, up and down die. The upper die is used to guide the blank and the lower die is formed, including the inlet part, the edge belt and the cavity.

Gear is a part that contains many parameters, usually including tooth number, tooth top circle, tooth root circle, modulus and so on. The gear parameters analyzed in this paper are: tooth number 11, modulus 2.117, pressure Angle 14.5o, top circle 29.6mm, root circle 21.2mm, displacement coefficient 0.66. The mold material is 20CrMo.

The outer circle of the gear is the shape of the blank. When the blank passes through the gear mold, the software is used to calculate the area: 501.6 mm2 for the gear, 706.5 mm2 for the round area of the blank with a diameter of 30 mm, then the intersecting area S is 204.9mm2, which is the area directly acted by the force. Assuming that the force F of the punch acting on the blank is 400kN (40t), the pressure P acting on the die is close to 2000MPa. So it is very important to optimize die structure and material properties.

Die inlet Angle a is a very important index. According to the formula P=Fcosa/(Scosa), when the inlet Angle is large, the pressure on the die can be greatly reduced.

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