Summary of Cutting Gear Manufacturers and Analysis of Damage Forms

Through research on the damage forms of domestic coal mining machine cutting teeth and anatomical analysis and impact resistance performance tests of some domestic and foreign excavation machine cutting teeth, manufacturers of rotary excavator cutting teeth have summarized that the main reasons for failure are as follows:
1 1. Low impact resistance
Through extensive observation of damaged cutting teeth, it was found that most of them were not normally worn and failed, especially in hard rock cutting where they were more severe. The reasons are as follows.
(1) The performance of alloy cutting heads is poor. There are graphite impurities in domestic alloys, uneven grain distribution, and cracks in some alloys, which are the main reasons for the cracking of hard alloy heads; Secondly, the domestic alloy pressing process is relatively backward, with a large density difference between the upper and lower parts of the alloy, multiple pores, and low hardness.
(2) The residual stress of alloy head brazing is high. Due to the significant difference in thermal expansion coefficients between the alloy blade and the tooth material, and the shrinkage difference during cooling increases with the increase of brazing temperature. Domestic cutting tools often use copper zinc brazing materials, with welding temperatures above 950 ℃ and high residual welding stress.
(3) The cracking and eccentric wear of the cutting tooth head cause the alloy head to lose its protective support prematurely. The main reason is that the performance of domestically produced raw materials is unstable, and some raw materials have severe looseness in the center, which leads to potential cracks inside the cutter body. Some cutting teeth cannot rotate themselves during operation, often causing eccentric wear of the tooth body.
1 2. Poor wear resistance
Wear resistance refers to the wear resistance of alloy cutting heads and tooth heads. Domestic cutting alloy generally has a high cobalt content, incomplete structure, low density, and low hardness, resulting in poor wear resistance of cutting alloy blades. However, the unstable quality and performance of raw materials, as well as improper heat treatment processes, result in cracks and low hardness on the cutting head, which affects its wear resistance.
Cutting tooth price
1 3 alloy heads removed
Cutting off the alloy head is one of the main forms of cutting failure. The phenomenon of cutting off alloy heads can be divided into early, middle, and late stages. The harm caused by the early dropping of the alloy head is significant. In a short working time, the hard alloy cutting head brazed on the cutting body will fall off the cutting body, causing the cutting teeth to be scrapped in advance. The main reasons for the alloy head dropping in the early and middle stages of the cutting process are poor weld quality, low strength, and lax control of the machining size of the cutting body, resulting in large or small weld gaps, making it difficult for the solder to flow and causing the alloy head to "squeeze" or "lack welding". For this reason, the coal industry standard MT246-1996 "Coal Mine Picks" issued by our country has put forward requirements for the welding seam of the picks, requiring the shear strength of the brazed weld seam to be ≥ 180 MPa, the shear strength of the brazed weld seam of excellent picks to be ≥ 230 MPa, and the filling degree of the welding material in the weld seam to be no less than 80%. Another reason for cutting off the alloy head is improper brazing process and poor pre welding treatment of the alloy head. The reason for the alloy head to fall off during the later stage of the cutting is due to excessive wear at the front end of the cutting body, which causes the hard alloy cutting head to protrude excessively and the weld area to decrease, resulting in insufficient weld strength and causing the alloy head to fall off. Therefore, to solve the problem of alloy head loss in the later stage of cutting, in addition to improving brazing quality and weld strength, it is more important to improve the wear resistance of the front end of the cutting body.