Analysis of the working principle of diamond wire drawing die for drawing

China is a big country of wire rod production, and its output is among the highest in the world. Wire rods are widely used in communications, construction, power and other sectors. In wire rod production, drawing is the most commonly used processing method. The application range of drawing processing is very wide, mainly used for drawing straight materials such as bar and wire. Drawing production solves the problem of wire materials that are difficult to process by turning and other methods. Its processing accuracy is relatively high, and its processing speed is fast. The waste of the blank is low and the utilization rate is high. The drawing die is a very important consumable die in the drawing of various metal wires. The cost of the drawing die accounts for more than 50% of the drawing cost. The drawing dies that are commonly used at present include alloy steel dies, cemented carbide dies, and diamond dies. Various drawing dies have their own advantages and disadvantages during use. Now, the working principle of the drawing die and the materials of the common drawing die, the classification of the drawing die wear and the influencing factors of the drawing process are described below.

Basic structure of drawing die

The basic structure of the drawing die, the main working area of the drawing die is the inner hole, the inner hole structure can be divided into the entrance area,

, Lubrication area, sizing area, exit area and follow the "smooth transition" theory, namely the drawing die hole

The junctions of the districts must have a small rounded transition. The drawn wire enters the drawing die from the entrance and acts on the drawing force i

Pass through the drawing die, and violent friction occurs on the conical surface of the working area of the drawing die, and pull out from the exit to obtain a smaller wire.

Drawing area size selection

(1) Entrance area

The angle of the entrance of the inner hole of the drawing die is one of the important parameters. It must be ensured that the contact point when the wire enters the die occurs

At the same height position in the reduction zone of the drawing die, it should be conducive to the entry of the wire. The entrance area of the drawing die provides a smooth profile that leads to the lubrication zone and the deformation zone, so that the lubricant can reach the working surface of the drawing die.

(2) Lubrication area

The role of the lubrication area is to store lubricant and enter it into the work area. According to different lubricant viscosity, wire diameter

And the length of the lubrication area, the cone angle of the lubrication area is different, in order to make the liquid lubricant can enter the work area smoothly, lubricate

Generally, a larger value should be selected for the cone angle. If it is too small, the lubricant should not enter, and the lubricant will not flow, or even form a wedge-shaped blockage.

If the cone angle in the lubrication area is too large, it is not easy to form a fluid dynamic pressure effect. The length of the lubrication area will also affect the lubrication effect. Generally speaking, no matter what kind of lubrication method, the longer the lubrication area, the better the lubrication effect.

(3) Work area

The working area is the area where the wire is plastically deformed, and its dimensional parameters include the working area cone angle a and the working cone length h2. The working cone angle a is the parameter of the drawing die. The size of the working area cone angle a plays a role in the size and distribution of the pressure acting on the inner hole of the drawing die, the size of the drawing stress and the mechanical properties of the wire being drawn. Decisive role.

The cone angle in the working area corresponding to the lowest drawing stress varies with the drawing environment, and there is an optimal cone angle range in the working area. It is difficult to ensure that the axis of the wire is concentric with the axis of the inner hole of the drawing die during drawing. In addition, the inner hole of the drawing die was worn too much during drawing before, which led to an increase in the diameter of the wire entering the inner hole. , So the length of the working area should be greater than the length of the actual deformation area.

(4) Sizing area

The diameter size of the sizing area is determined according to the allowable tolerance of the wire and the elastic deformation of the wire during drawing, and taking into account the service life of the mold, the negative tolerance size of the wire is usually selected.

When determining the length of the sizing area, the following requirements should be met: sufficient wear resistance, energy consumed during drawing, and the possibility of breaking the wire. Although the sizing area is too long, the service life of the wire drawing die can be increased, but at the same time, it also causes friction, heat generation and energy consumption to increase, and it is easy to cause the wire diameter to be reduced or the wire to be broken. If the sizing area is too short, it will cause the wire to sway during the drawing and produce a slub shape, and also cause the inner hole of the drawing die to wear quickly, resulting in excessive size. In general, the larger the diameter of the drawn wire, the shorter the length of the sizing zone.

(5) Export zone

The exit zone forms an angle of 90 degrees in the drawing die. Such an angle facilitates a specific wider outlet, so that the drawing die can be restored to its original size multiple times without further processing. The export zone is often considered unimportant. But if the drawing die has no exit zone, the trailing edge of the sizing belt will crack or flake, resulting in damage to the drawing die