Do you encounter the following situations in metal wire production?
1. The wire diameter fluctuates greatly during wire drawing.
2. The drawing die cracks soon.
3. The service life of drawing die is too short.
4. The surface of wire is cracked and rough.
Let's take a look. Why?
Drawing die is a very important consumable die in various metal wire drawing production. The cost of drawing die accounts for a large proportion of drawing cost. As a wire rod production enterprise, how to reduce the cost, obtain stable and long-time drawing, accurate size and better surface quality is very important.
But how? Of course, it is difficult to achieve without high quality drawing die. Under the condition of certain die material, the pass structure is the key factor to determine the quality of drawing die, because different drawing conditions need different pass structure to adapt to it. Only in this way can the service life of the drawing die be prolonged and great economic benefits be created. Therefore, the wire drawing die is very important to the enterprise.
Today we will focus on the two most important areas of the lower drawing die - compression zone and sizing zone.
1. Compression zone
The compression zone is the area of wire drawing deformation, and the angle of compression zone (compression angle) is the main parameter of the compression zone of wire drawing die. The size of compression angle plays a decisive role in the size and distribution of the pressure acting on the inner hole of the drawing die, the size of drawing stress and the mechanical properties of the drawn wire rod.
If the angle of the compression zone is too large, the deformation rate will increase and the deformation zone will become smaller when the metal material is in the control process, which will make the drawing die produce a lot of heat, scorch the lubricating powder and make it invalid, thus seriously affecting the wire drawing effect. At this time, if the compression zone is not cooled, the drawing quality of the metal wire will be directly affected; if the angle of the compression zone is larger or the compression rate is smaller, the metal material will be closer to the sizing belt during drawing, and the deformation will be greater, so that it is difficult to reach the specified area of the sizing belt, and the concave convex phenomenon will be formed on its surface. If the material texture is soft, it will occur in the drawing process Ellipse phenomenon.
At this time, the area of the lubrication area increases, which can reasonably provide better lubrication effect, but it is not the case in practice. On the contrary, due to the increase of the surface relief area, the lubricating powder will flow out of the mold hole in reverse direction, thus reducing the lubrication effect, and finally leading to the formation of cracks on the surface of metal wire, or the appearance of scratch marks. Therefore, the angle of the compression zone should not be too large, which will easily make the lubricating powder lose the lubrication effect, and then affect the wire drawing quality.
What happens if the compression zone angle is too small? When the angle of the compression zone becomes smaller, the drawing die will produce a lot of heat, which will lead to the failure of lubricating powder. Because when the angle is too small, the contact point of the metal material is close to the top of the compression zone, which makes the deformation area larger, which leads to the increase of the useless power of the drawing die and a large amount of heat. In addition, when the area of the lubrication area is reduced, the lubrication function decreases because of the decrease of the lubrication amount. And then affect the wire drawing quality. When the tensile stress increases, the diameter of the sizing belt will become larger, which makes the ellipse phenomenon easy to appear, which will lead to the wire breaking and shrinkage.
2. Sizing area
The sizing area is the control part of the die aperture size, through which the metal wire can get the final size. Reasonable sizing zone length can improve flatness, dimensional accuracy, surface roughness quality and die life.
The longer the sizing zone is, the larger the contact area between the wire and the die hole, and the friction force will also increase greatly. Therefore, the long sizing zone will increase the tensile force. However, the tensile stress must be greater than the tensile strength limit of the wire rod before the stretching process can be carried out. Otherwise, the wire breaking phenomenon will be caused and the drawing cannot be carried out. Therefore, it is very important to find a suitable sizing zone length for drawing different grades of metal wire.
The sizing zone must be straight and reasonable in length. If the sizing area is too long, the pulling wire friction force will increase. When the wire rod is pulled out of the die hole, it is easy to cause diameter reduction or wire breakage. If the sizing area is too short, it is difficult to obtain the wire rod with stable shape, accurate size and good surface quality, and the die hole will wear out of tolerance quickly.
To sum up, as a wire rod production enterprise, in order to obtain stable long-time drawing, accurate size, good surface quality, reduce cost and create large economic benefits, it is necessary to detect the groove structure of wire drawing die. |
