Influence of die structure design

1. Reasonable design

The mold is mainly designed according to the use requirements, and its structure sometimes can not be completely reasonable, uniform and symmetrical. This requires the designer to take some effective measures when designing the mold without affecting the performance of the mold, and try to pay attention to the manufacturability, the rationality of the structure and the symmetry of the geometry.

(1) Try to avoid sharp corners and sections with great thickness difference

Sections, thin edges and sharp corners with great thickness differences shall be avoided. Smooth transition shall be made at the junction of thickness and thickness of the die. This can effectively reduce the temperature difference of the die section and reduce the thermal stress. At the same time, it can also reduce the different timing of tissue transformation on the section and reduce the tissue stress. The transition fillet and transition cone are adopted.

(2) Properly increase process holes

For some molds whose cross-section can not be guaranteed to be uniform and symmetrical, on the premise of not affecting the service performance, the through holes should be changed into through holes, or some process holes should be added appropriately. The concave die with narrow cavity will deform after quenching. If two process holes can be added in the design, the temperature difference of the section in the quenching process is reduced, the thermal stress is reduced, and the deformation is obviously improved. Adding process holes or changing non through holes into through holes can reduce the increased cracking sensitivity due to uneven thickness.

(3) Closed and symmetrical structure shall be adopted as far as possible

When the die shape is open or asymmetric structure, the stress distribution after quenching is uneven and easy to deform. Therefore, for the grooved die that is easy to deform, the reinforcement should be reserved before quenching and then cut off after quenching. The grooved workpiece is deformed at R after quenching. After reinforcement, the quenching deformation can be effectively prevented

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(4) Adopt combined structure

For complex shapes and sizes & gt; For 400mm large concave die and punch with small thickness and large length, it is better to adopt the combined structure, which can simplify the complexity and reduce the size. The inner surface of the die can be changed into the outer surface, which is not only convenient for cold and hot processing. And it can effectively reduce deformation and cracking.

When designing the combined structure, it shall generally be decomposed according to the following principles without affecting the matching accuracy:

(1) Adjust the thickness so that the die with wide difference in section is basically uniform after decomposition.

(2) Decompose in the place where stress concentration is easy to occur, disperse its stress and prevent cracking.

(3) Cooperate with the process hole to make the structure symmetrical.

(4) It is convenient for cold and hot processing and assembly.

(5) It is important to ensure usability.

If the integral structure is adopted for the large die, it will not only be difficult for heat treatment, but also the shrinkage of the cavity after quenching is inconsistent, and even cause concave convex and plane distortion of the edge, which is difficult to remedy in the later processing. Therefore, the combined structure can be adopted. It is divided into blocks, assembled and formed after heat treatment, grinded and matched, which not only simplifies the heat treatment, but also solves the problem of deformation.