Physical Performance Tungsten Carbide Drawing Dies Component Of Wolfram And Cobalt

Introduction:

The tungsten carbide drawing die is made up of highly polished, heterogeneous holes through which the wire is drawn to reduce its diameter. The choice of mold materials, i.e. natural or synthetic single crystal diamond, polycrystalline diamond, cemented carbide, etc., depends on the material and working parameters of the wire to be drawn. Cemented carbide drawing dies are used in the wire drawing industry, drawing such as low carbon steel, high carbon steel, stainless steel, brass, aluminum and other different materials.

The drawing process of the carbide drawing die, as its name indicates, is to draw the wire with large diameter through the hole of the drawing die plastic deformation under the condition of guaranteeing the overall volume unchanged.

In more technical terms, it is the process of producing multiple sizes of wires within specified tolerances. The process involves reducing the diameter of a rod or wire through a series of holes in a drawing die, where the holes in the continuous die are smaller than those in the previous die. When the thread passes through the hole of the last mold of the series, the final size of the wire is achieved.

Manufacture Processing:

Carbide drawing die blank, die sleeve processing and core assembly process should pay attention to the key points; the main four manufacturing steps:

1. die blank processing;

2. mounting interference;

3. drawing die sleeve processing;

4. mounting process.

Mould blank processing

The core of carbide drawing die will shrink in the sintering process, and the shrinkage of different batches is different because of their composition, pressing and sintering process, and the different parts of the blank often form "saddle" or "horn mouth" shape because of the different shrinkage. The fluctuation of the shape and dimension of the die blank conforms to the standard of the die blank, but it is far beyond the interference requirement of the die set, which causes the die core to bear the prestress unevenly and the service life of the die to be greatly reduced. Therefore, the die blank must be grinded in an outer circle, and special clamps and diamond grinding wheels should be used on the grinder.

Interference fit

In order to make the core get certain prestress, the diameter of the inner hole of the sleeve should be smaller than the outer diameter of the core. The difference between the two is called interference. The magnitude of interference should be determined according to the size and deviation of the die core, drawing stress and inserting method. Table 1 actual interference level for die inserting. The die set is inlaid with hot pressing method and cold pressing method. The interference of cold pressing method is small, and the prestressing stress obtained is also small. It is mostly used to manufacture wire drawing dies with small specifications and for drawing soft metals.

Die sleeve processing

The die sets are machined by lathe turning, and the main points of control are as follows:

(I) the roughness of the inner diameter of the die set must reach 0.80 I.6 m, which is beneficial to match closely with the die sleeve.

(2) the inner diameter of the die sleeve should be one-to-one corresponding to the external diameter of the die blank, so as to ensure the accuracy of each mold interference.

(3) the bottom surface of the inner hole of the mold sleeve must be parallel with the outer end of the mold, and ensure that the center of the die hole is vertical after the sleeve is installed.

(4) the ellipticity of the inner hole of the mold sleeve should be as small as possible and should not be greater than 0.02 mm. When hot loading, the outer surface of the mold sleeve should be light and ensure uniform cooling after installation.

Installation process

The cold pressing process is pressing the die blank into the mould sleeve at room temperature with a press. The cold pressing method requires accurate interference and high dimensional accuracy of die core and die sleeve. The advantages of the cold pressing method are that it does not need heating equipment, saves energy and reduces cost.