the first method
After grinding the two supporting surfaces and the observation surface of the diamond, the processing of each process is carried out. Its advantage is that the transparency of the diamond can be used to observe the processing processes such as open holes. Its disadvantage is that part of the diamond needs to be ground off; the diamond is small and it is inconvenient to fix it during processing. Use this method when processing small diameter die holes.
The second method
After sintering the diamond and related powders into a block and inserting the sleeve, the processing of each process is carried out. The disadvantage of this method is that it cannot directly observe the processing process of the die hole. Its advantage is that 2/3～4/5 of the diamond is less than the previous method. It is easy to determine the center, and it is convenient to process and operate the mold. It is often used for processing large diameters. Diamond die hole. When the diamond die is used for drawing, when the surface of the die hole has stripes, metal sticking, the wear of the die hole is elliptical, and the diameter of the sizing belt increases, it needs to be re-grinded and reused after increasing the diameter of the die hole. Re-grinding can be performed many times until cracks occur in the diamond.
2. Processing method of hard alloy wire drawing die
Mainly use mechanical grinding processing method, the process is as follows:
Select blank → insert sleeve → work cone polishing → lubrication cone polishing → exit cone (zone) polishing → sizing belt polishing → transition zone polishing → working cone polishing → sizing belt polishing → inspection and acceptance.
In addition, there are chemical-mechanical grinding processing method, ultrasonic processing method, electric fire processing method, electrolyte processing method and so on. In the process of drawing, the hard alloy die hole has defects such as groove marks, oval shape, and metal adhesion on the surface due to wear. It needs to be re-grinded, and the die hole diameter is enlarged to the adjacent die hole size to continue to use. Re-grinding can be performed many times until the mold wall is reduced to cause cracks.
3, the selection of the material of the drawing die and its application characteristics
Diamond and cemented carbide are the main materials for wire drawing die processing. The application of the two materials is quite different and each has its own characteristics.
Diamond is the molding material with the highest hardness, excellent wear resistance, brittle quality, and high price among the known materials. This kind of wire drawing die is difficult to process. Generally, molds with a wire diameter of less than 1.0mrn are made. At present, the diameter of the largest diamond die has reached 2.5mrn.
Cemented carbide adopts tungsten-cobalt cemented carbide, which is composed of tungsten carbide and cobalt. Tungsten carbide is hard and wear-resistant as the "skeleton" of the alloy, and cobalt is the bonding metal, which increases the toughness of the alloy. As the cobalt content increases, the density, hardness, compressive strength, elastic modulus, thermal conductivity and resistivity of the alloy decrease, while the toughness and flexural strength increase. As the content of tungsten carbide increases, the performance of the alloy is just the opposite of the above-mentioned increase in cobalt content. Cemented carbide has high wear resistance, corrosion resistance, alkali resistance, good properties of anti-emulsion and other lubricating materials. Cemented carbide wire drawing dies are widely used in the drawing production of various metals and alloy wires.
Steel drawing dies made of other molding materials have low cost, convenient processing and repair, but it has low hardness, poor wear resistance, and short service life. After the 1970s, it has actually been used as molding materials such as cemented carbide and diamond. Replaced. The hardness and wear resistance of synthetic diamond is second only to natural diamond and better than cemented carbide, and the price is significantly lower than natural diamond. It is a good material for making wire drawing dies. The polycrystalline wire drawing die made of synthetic diamond has been used in the production of rough drawing and middle drawing of copper wire and steel wire.
