Stamping and cold extrusion technology is related to die price

As the stamping history of die manufacturers is relatively long and the technology is relatively stable, and cold extrusion is in the bottleneck period of technology, there are some technical restrictions and anti blocking conditions. Today, Chengda and everyone summarize the difficulties of stamping and cold extrusion technology:

1. Stamping

If the distance between the contour and the inner hole edge is less than the plate thickness, the inner diameter is more than half of the outer diameter, and the height is more than 1.5 times of the inner diameter, the constraint punching effect is better. Due to the close distance between the profile and the edge of the inner hole, the force of the punching needle will affect the profile and change the size of the profile. In order to prevent changes in the overall dimensions, it is necessary to keep this part of the outline in a constrained state. Due to the binding force, the stamping part is in a state of compressive stress. Under this state of blanking compressive stress, the stamping effect of all bright strips can be obtained by taking appropriate clearance.

2. Cutting extrusion forming

Generally, the bolt head is formed by cold heading plastic processing, and the cutting extrusion process has more advantages than the bulging process. Before the cutting extrusion forming, the blank needs to be reshaped, and the blank meeting the process requirements can be obtained by reshaping. The size of the blank shall be paid attention to. The blank shape before extrusion shall be determined according to the conditions of the parts. The blank shape that is conducive to material flow shall be adopted. If the blank size is too large, that is, the cutting extrusion allowance is too large, the required cutting extrusion force will be large, which is likely to reduce the life of the cutting extrusion die, increase the possibility of accidental damage to the die, and consume raw materials; The cutting and extruding allowance is too small, the parts are easy to fall off corners after cutting and extruding, the shape is incomplete, and the appearance quality is not satisfactory.

The die structure focuses on the design and processing of the cutting extrusion film. The working size of the cutting edge needs to be controlled at the middle and lower limits. The angle of the cutting extrusion die needs to be appropriate. The cutting edge needs to be grinded and polished. The roughness is Ra0.025 to Ra0.050 μ m. It has a long service life.

3. Drawing and Forging

The protruding thick wall part formed by cold extrusion and the cup shaped special-shaped part formed by deep drawing are combined into one, and the fastener formed by the composite forming method of deep drawing and compression with the sheet metal as the material is characterized by the forming of the protruding head and the increase of the wall thickness.

4. Local forming

Upsetting forming has two concepts: one is all upsetting, that is, there is a force on the end faces of all products; The second is local upsetting, that is, only the required part has applied pressure. Due to large processing area and high forming load, large tonnage stamping machine is required for all forming. For local forming, lower load can be used to obtain the required thickness change, which is widely used in the forming of holes and grooves.

① Step part

Take the joint as an example to illustrate the key points and application of forming. Engineering design: turning - annealing - phosphorus saponification - extrusion (forming steps by semi closed extrusion) according to the design drawing.

② Micro local forming

For the need of locking and chip removal, there are 1~3 chip scraping grooves for some set screws, which can be processed by extrusion process. The typical one is the forming of chip scraping grooves for automobile assembly bolts.