Carbide wire drawing die manufacturing steps

       

1 The amount of interference installed

In order to obtain a certain prestress of the mold core during installation, the diameter of the inner hole of the mold sleeve must be smaller than the outer diameter of the mold core, and the difference between the two is called the interference. The amount of interference should be determined according to the die core size and deviation, drawing stress and inserting method. Table 1 shows the actual interference when the mold is installed. The die set is inlaid with two kinds of hot pressing method and cold pressing method. The cold pressing method has a small interference and a small pre-pressing stress. It is mostly used to manufacture small-sized wire drawing dies for drawing soft metals.

2 Mold blank processing

Cemented carbide wire drawing die cores will shrink during the sintering process. Different batch numbers have different shrinkage due to differences in composition, pressing and sintering processes. Each part of the die blank often forms a "saddle" or "saddle" due to the difference in shrinkage. "Bell mouth" shape. Although the fluctuation of the shape and size of the mold blank meets the standard of the mold blank, it far exceeds the interference requirement when the mold is set. This causes serious unevenness in the prestress of the mold core during installation and greatly reduces the service life of the mold. Therefore, the mold blank must be For external cylindrical grinding, a special fixture is required on the grinder and a diamond wheel is used for grinding.

3 Mold sleeve processing

The die sleeve is formed by turning on a lathe, and the main points of control during processing are as follows:

(I) The inner diameter roughness of the die sleeve must reach 0.80-I. 6 m, which is conducive to close cooperation with the mold sleeve;

(2) The inner diameter of the mold sleeve must correspond to the outer diameter of the mold blank to ensure the accuracy of the interference of each mold;

(3) The bottom surface of the inner hole of the mold sleeve and the outer end of the mold must be parallel, and ensure that it is perpendicular to the center line of the mold hole after the sleeve is installed;

(4) The ovality of the inner hole of the die sleeve should be as small as possible, and should not be greater than 0.02 mm. When hot assembling, the outer surface of the die sleeve should be polished to ensure uniform cooling after assembling.

Table 1 Mould set with interference 

4 Installation process

The cold pressing process is to press the mold blank into the mold sleeve with a press at room temperature. The cold pressing method requires accurate interference and high dimensional accuracy of the mold core and mold sleeve. The advantage is that it does not require heating equipment, saves energy and reduces costs.