Picks are tools used by mining machines such as coal mining machines, plows, and roadheaders to break rock and coal in coal mining, roadway excavation, and tunnel construction. In recent years, in the context of China's increasing demand for coal and the application of high-power fully mechanized mining machinery to coal mining, the demand and loss of picks are enormous. In order to improve the reliability and service life of the pick, the usual measures are:
1. New materials
In order to meet the development requirements of coal mining machinery, the problem of poor wear resistance and easy to fall off of the hard alloy picks produced by the existing technology is solved. Some new alloy steels are gradually applied to the production of picks, such as air-cooled Bayesian. Body steel, new series of quasi-bainite steel and high toughness secondary hardening steel.
2, brazing - heat treatment integration technology
Due to the small deformation and simple process of brazing, brazing is often used in the connection of the carbide tip and the tooth body. The brazing material is generally made of a high melting point brazing filler metal such as a copper base and a silver based brazing filler metal. The copper base is used as the brazing material, and the brazing temperature ranges from 880 to 950 °C, and the residual stress is large, and the second heat treatment of the tooth body is required to fully exert its comprehensive performance.
3. Surface strengthening of the pick tooth
1) Thermal spraying technology
By spraying a high-hardness wear-resistant alloy that can be combined with the tooth height in the pick body, the hardness and wear resistance of the pick are greatly improved, and the life can be improved.
2) Cladding technology
Cladding is achieved by combining the coating material with the substrate to achieve surface modification or repair. Laser cladding is the simultaneous melting of the coating material and the surface material of the substrate by high-energy laser irradiation to form a metallurgically bonded additive cladding layer.
3) Surfacing coating technology
Using surfacing technology, the alloy with Cr, W and V as the main elements in the pick head makes the coating structure similar to tungsten alloy steel, which can greatly improve the wear resistance, corrosion resistance and resistance of the pick. Impact ability.
4) Surface chemical heat treatment technology
Surface chemical heat treatment is a technique for obtaining a high-performance special composite material by different chemical reaction on the surface of the material. Since the failure and damage of the picks are mainly germinated in the surface layer, the pick-up can be greatly improved after chemical heat treatment. Anti-adhesive wear and corrosion resistance.
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