Types, properties and applications of wire drawing and stranding molds

Mold classification

Such molds are generally called wire molds, which can be divided into round molds and molds. Commonly used wire mold materials include diamond molds, cemented carbide molds, and polycrystalline molds.

a Diamond mold: Diamond mold, also known as diamond, has the highest hardness and wear resistance, but it is more expensive. In the drawing, it is generally used to pull small specifications of monofilament, such as Φ0.40mm and below specifications.

b Cemented carbide mold: In the production of tensile steel, the tungsten steel mold used in the past is replaced by a hard alloy mold. Because the cemented carbide die has better wear resistance, better polishing property, less adhesion to the metal to be processed, less friction coefficient, higher thermal conductivity and high corrosion resistance than the steel die. .

c Polycrystalline mold: also known as synthetic diamond, is the most commonly used mold mold, it has wear resistance, but also has the disadvantage that the surface of the product is not smooth.

d Tungsten steel mold: It is commonly used for aluminum drawing, and has a short service life. It is generally used for bridge molds. The tungsten steel mold has good wear resistance and low price. Its strength is not suitable for copper pulling. The surface of the drawn core is not smooth. .

Mold hole structure

Entrance area:

Generally, there is a circular arc, which is convenient for drawing the wire into the working area, and is not damaged by the edge of the die hole; the lubricating fluid is saved and plays the role of lubricating the drawn wire, and the part of the drawing die hole is used to increase the height of the working area. It is generally 25% of the total height H of the mold blank and the angle is 60 degrees.

Work area:

It is an important part of the entire die hole, and the metal tensile plastic deformation is the cross section of the metal material passing through this zone. The choice of this area is mainly height and cone angle. The principle of height selection is:

a) The drawn soft metal wire should be drawn with a short hard metal wire;

b) The small diameter wire should be drawn to draw a larger diameter wire;

c) wet stretching should be dry lubrication stretching to be short;

d) generally 1 to 1.4 times the diameter of the sizing zone d.

The working cone angle is selected according to the following principles:

a) The smaller the compression ratio, the smaller the working cone angle.

b) the harder the drawn material, the smaller the working cone angle,

c) The material of the small diameter material is small. Generally, when the metal and its alloy are stretched, the angle is 16 to 26°, the taper angle of the general drawn copper wire is 16-18°, and the taper angle is 20 when the aluminum wire is pulled. ~24°.

Sizing area:

Its role is to make the final size of the product, the principle of its height selection is:

a) The drawn soft metal material is shorter than the drawn metal material;

b) The drawing of large diameter materials should be shorter than the drawing of small diameters;

c) The wet stretching is shorter than the dry lubrication stretching, and h = 0.5 to 1.0 d is generally selected.

Export area:

The exit zone is the last part of the drawn material leaving the die hole. It can protect the sizing zone from cracking. The taper angle of the exit can prevent the wire from being damaged at the exit of the sizing wire and the wire is backed up when the machine is stopped. Generally, it is 45°. . The ratio of the strength limit of the metal to the tensile stress is called the safety factor of the stretch. Its system range: 1.4 ~ 2.0.