Cutting picks are tools used in coal mining machines and mine tunneling machinery, and their quality directly affects the efficiency of mining machines and the production cost of enterprises. With the increase in people’s demand for energy, especially coal, to improve mining efficiency, the power of the shearer is continuously increasing, and the quality requirements for the cutting pick are getting higher and higher, which requires high strength, hardness and wear resistance, high bending strength and corrosion resistance to prevent fracture, bending, deformation and early wear loss during the use of cutting picks. Since the consumption of the pick is very high, to reduce its consumption, we can study the manufacturing process of cutting picks to reduce its consumption.
The manufacturing process of cutting picks includes the production process and surface treatment, and the surface treatment of the cutting pick is an effective way to improve its service life.
Production process of cutting pick
There are two main production processes for cutting pick. One is that the rolled bar is forged into a pick blank by die-forging, machined into a skirt body, and then the cemented carbide of the pick head is brazed, followed by heat treatment. The other process can use the casting method to make a pick blank or the method of insert casting to make a pick. Casting cutting pick manufacturing process for skirt body and carbide composite casting molding, and then mechanical processing and heat treatment.
Cutting pick surface treatment
Surface treatment of the surface of the pick material in contact with the coal seam is one of the effective ways to improve the wear resistance and service life of cutting pick, and there are four methods.
Cemented carbide surfacing
According to the force situation of cutting picks, the maximum force point of cutting picks occurs at the cutter head which cuts with the coal seam. This part wears the most seriously. To improve the wear resistance of the working part of the pick cutter head, for picks with poor hardenability or hardenability of the pick material, the contact part of the pick and the coal seam is surfacing with wear-resistant alloy. The method improves the hardness and wear resistance of the working part of the pick. The surfacing welding of the wear-resistant layer of the cutting pick is to use the high hardness and high wear resistance of the surfacing material to deposit one or several layers of surfacing material on the head of the pick tooth body to form a protective belt. This layer has high excellent wear resistance and good corrosion resistance so that the tooth of the skirt body material does not directly contact the mined coal rock, reduces the friction and impact between the tooth head storage material and the coal seam, and slows down the wear loss rate of the trunnion and extending the service life of the trunnion. The advantages of overlay welding are simple equipment, low cost, flexible operation, and can adapt to the full range of overlay welding.
Surface thermal spraying
Thermal spraying technology is a method that uses a heat source to heat the wear-resistant material to be sprayed to a dissolved or semi-soluble state and to form a coating on the surface of the pretreated substrate by spray deposition at a certain speed.
Surface metallurgy method
Surface metallurgy technology uses plasma arc as the heat source to obtain a layer of uniform, dense, and firmly bonded special protective coating on the surface of the substrate to realize the metallurgical bond between the coating and the metal substrate. Plasma cladding is a rapid non-equilibrium solidification process, has multiple strengthening effects such as supersaturated solid solution strengthening, dispersion strengthening, and precipitation strengthening, and the obtained metallurgical layer has very high wear resistance, corrosion resistance, high-temperature oxidation resistance, and other properties.
Chemical heat treatment
Chemical heat treatment is to carburizing, boron, chromium, and other treatments on the surface of the cutting pick to form a compound with a higher hardness on the surface of the cutting pick and enhance the surface wear resistance. Carburization is heat preservation in a definite carbon potential environment, through the adsorption and diffusion of carbon atoms to improve the carbon content and the formation of fine carbide particles on the surface of the cutting pick, to improve the hardness of the surface of the cutting pick. Through 40CrNiMo boron and chromium treatment, a compound of boron and chromium is formed on the surface to improve the surface hardness and wear resistance to increase the service life of the cutting pick.
