How to determine the dimensional accuracy of automotive stamping parts?

2019-12-25 10:32:49

In the production process of metal stamping parts, we will encounter the situation that the punch size is too large or too small and the difference between punch size and punch size is large. In order to solve this problem, we should not only consider the planning size, processing accuracy and blanking clearance of forming punch and die, but also think about the following aspects.

1. As a result of the rough edge of the punching part during blanking, it is necessary to study the cutting edge and check whether the blanking clearance is reasonable. It is mainly aimed at U-bend and V-bend. The key to solve the problem is to guide the stamping parts before bending, during bending, and to press the material to prevent the stamping parts from sliding during bending.

2. The tensile stress of the material increases, and the tendency of turning over and twisting of the stamping parts increases. When turning over occurs, the punching size tends to be smaller. The strong pressure on the material causes the deformation of the material, which will lead to the increase of the punching size. When the pressure is reduced, the punching size will be smaller.

3. If a bevel or arc is made at the end, the punching size will be larger because the punching force is relieved and the punching parts are easy to turn over and smear. When the end of the punch is flat (no bevel or arc), the punch size will be smaller.

The dimensional accuracy of automotive stamping parts is measured by tolerance registration. According to the national standard, it is divided into 20 grades. From IT01, it0, it1, it2 to it18, the larger the number is, the lower the tolerance grade (machining accuracy) is, and the larger the allowable variation range (tolerance value) is, the smaller the machining difficulty is.

The dimensional accuracy of hardware stamping parts refers to the difference between the actual size and the basic size of the stamping parts. The smaller the difference, the higher the dimensional accuracy of hardware stamping parts. The main factors that cause the dimensional error of metal stamping parts are: the manufacturing accuracy of punch and die; the gap between punch and die; the elastic recovery of materials after stamping; the accidental factors in the production process, such as inaccurate positioning, unstable material performance, etc.

The dimensional accuracy of metal stamping parts can be generally divided into two categories: ordinary level and precision level. The common level is the precision that can be achieved by more economical means. Precision level is the precision that stamping technology can achieve.