The invalidation causes of cemented carbide wire drawing dies include longitudinal cracks, transverse cracks, core removal, number running, normal wear, and damage. The analysis is as follows:
Longitudinal cracks of cemented carbide wire drawing die: the outer circle of cemented carbide die core is not processed, the processing quality of the inner hole of the die sleeve is poor, the tapered hole, trapezoidal hole, insufficient inserting interference, unreasonable geometric angle, and excessive compression , Cemented carbide defects or improper selection of grades, insufficient tensile strength of the material;
Cemented carbide wire drawing die transverse crack: the cemented carbide outer circle is unprocessed, the inner hole of the die sleeve is of poor processing quality, is stepped, the upper and lower interference of the insert is different, the defect of the cemented carbide, the improper brand selection, the material tensile strength is insufficient ；
Carbide wire drawing die run number: Carbide material is not wear-resistant, and the lubrication is not good during stretching operation;
Cemented carbide wire drawing die core removal: there is almost no interference in the insert, and the quality of the die sleeve material is poor;
The invalidation of the cemented carbide wire drawing die is summarized as the cemented carbide material, mold processing, manufacturing and die sleeve material reasons. As far as the current situation is concerned, improving the quality of carbide materials for drawing dies includes reasonable brand selection, material design, ensuring high wear resistance, high tensile strength, and reasonable pass design (lubrication area, working area, Positioning area, exit angle, size design) is the key to improving the overall level of the drawing die.
The wear problems of cemented carbide wire drawing die are as follows:
When drawing high-carbon steel, especially high-carbon steel, spring steel, extra-hard steel, high-viscosity alloy steel, etc., the currently used WC/Co cemented carbide often exhibits insufficient wear resistance or insufficient tensile strength, and has a long life. It is not ideal. When this type of material is stretched, the surface will adhere and diffuse. At the interface of this type of material, the stretched material will diffuse into the cemented carbide. The stretched material has a higher carbon content and Fe diffuses. The number rate is relatively weak, and the diffusion of Co in the alloy into the stretched material is extremely strong due to the high carbon of the material. The strong diffusion of cobalt makes the alloy wear sharply, thereby weakening the bonding of WC/Co on the surface of the cemented carbide, and the loose WC phase is quickly peeled off by the tensile material. Under dry grinding conditions without cooling, this wear tends to be accelerated due to thermal fatigue effects.
The wear problem of cemented carbide drawing die is mainly caused by the diffusion and consumption of cobalt when drawing high-carbon materials, which weakens the bonding of WC/Co. Therefore, inhibiting or preventing this Co diffusion is to solve the wear of this type of material and prolong its use. The key to longevity.
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