The requirement of cold heading is high. During cold upsetting, the deformation resistance of the blank is significantly increased due to the three-dimensional compressive stress in the die, which makes the stress of the die much larger than that of the general stamping die. When cold extruding steel, the stress of the die is usually 2000 MPa ~ 2500 MPa. For example, to make a cup-shaped piece of low carbon steel with a diameter of 38mm, a wall thickness of 5.6mm and a height of 100mm, for example, when cold heading is used, the larger deformation force is only 17T, while when cold extrusion is used, the deformation force is 132t, at this time, the unit pressure acting on the cold extrusion punch is more than 2300mpa.

1) Large tonnage press is needed. Because of the large deformation resistance of the blank during cold extrusion, hundreds of tons or even thousands of tons of press are needed.

2) Because of the high cost of cold upsetting die, it is generally only suitable for mass production of parts. It is suitable for cold heading of 50000-100000 pieces in small batch.

3) The surface of the blank needs to be treated before extrusion. This not only increases the working procedure, needs to occupy a larger production area, but also is difficult to achieve production automation.

4) It is not suitable for processing of high-strength materials.

4) The plasticity and impact toughness of the cold heading process become worse, and the residual stress of the part is large, which will cause the deformation and corrosion resistance of the part to reduce (stress corrosion).

In addition to high strength, the die also needs to have enough impact toughness and wear resistance. In addition, the strong plastic deformation of the metal blank in the mold will raise the mold temperature to about 250 ℃ ~ 300 ℃, so the mold material needs certain tempering stability. Because of the above situation, the life of cold extrusion die is far lower than that of stamping die.

More customized products, please contact us!