Stamping and cold extrusion technology and die price

Because die manufacturers have a long history of stamping and technology is relatively stable, and cold extrusion is in the bottleneck stage of technology, there are some technical constraints and anti-blockade status. Today Chengda and you sum up the difficulty of stamping and cold extrusion technology:

1. Stamping

The distance between the shape and the edge of the inner hole is less than the thickness of the plate, the inner diameter is more than one-half of the outer diameter, and the height is more than 1.5 times of the inner diameter. Because of the close distance between the shape and the edge of the inner hole, the force of the punch will affect the shape and change the size of the shape. In order to prevent the change of the shape size, it is necessary to make this part of the shape in a restrained state. Because of the restraint force, the stamping part is in the state of compressive stress. In this state of pressing stress, the stamping effect of all bright bands can be obtained by taking appropriate clearance.

2. Cutting-extrusion Forming

Usually, the forming of bolt head adopts cold upsetting plastic processing, and the cutting-extrusion process has more advantages than the bulging process. Before the cutting and extrusion forming, the blank needs to be shaping, through shaping, the blank that meets the technological requirements can be obtained. The size of the blank needs to be paid attention to. The shape of the blank before extrusion should be determined according to the condition of the parts. The shape of the blank which is beneficial to material flow should be adopted. If the blank size is too large, that is, too much cutting and extrusion allowance, the required cutting and extrusion force will be larger, which will easily cause the life of the cutting and extrusion die to decrease, the possibility of accidental damage of the die will increase, and raw materials will be consumed; if the cutting and extrusion allowance is too small, the parts after cutting and extrusion are prone to corner fall, the shape is incomplete, and the appearance quality will not be satisfactory

The die structure focuses on the design and processing of the cutting and extrusion film. The working size of the cutting edge needs to be controlled in the middle and lower limits. The angle of the cutting and extrusion die should be appropriate. The cutting edge needs to be grinded and polished. The roughness of the cutting edge ranges from Ra0.025 to Ra0.050 um, which has a high life.

3. Deep drawing and forging

The cold extrusion forming bulge thick-walled parts and the deep drawing cup shaped parts are combined into one. The sheet metal is used as the material and the composite forming method of drawing and compression is used to form the fastener. Its forming characteristics are the forming of head bulge and the increase of wall thickness.

4. Local Forming

There are two concepts in upsetting forming: one is total upsetting, that is to say, it exerts force on the end face of the whole product; the other is partial upsetting, that is, it exerts pressure only on the part needed. Because of large processing area and high forming load, large tonnage stamping machine is needed for whole forming. For local forming, the required thickness change can be obtained by lower load, which is widely used in hole and groove forming.

Step Parts

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

(2) Micro Local Forming

For the need of locking and chip removal, there are 1 to 3 scraping grooves for some fastening bolts, which can be processed by extrusion technology. The representative is the formation of scraping grooves for automobile combination bolts.