How can the cutter manufacturer improve the performance of the excavator cutter?

How can the excavator cutter manufacturer improve the performance of the cutter?
The shearer cutter is a tool that directly crushes coal and is the main equipment for achieving modern coal construction. It is often subjected to strong impacts and wear during work, and the replacement of cutting teeth is also frequent. In the process of use, it can reduce labor and improve employee safety. As the main load-bearing force in the construction process of the coal mining machine, the consumption of cutting teeth directly affects the cost of coal mining. Therefore, designing a cutting tooth with a reasonable structure and correct material selection is of great significance.
During the process of hitting the coal rock mass with a pickaxe shaped pick, the tip of the pick is wedged into the coal rock mass at a certain angle, gradually crushing the compressed part of the coal rock mass. As the depth of the cutting teeth increases, the compressive tension inside the coal rock mass gradually increases, causing the cross-section of the crushed coal rock mass to continuously expand. At the same time, the surface of the compressed area will undergo significant elastic deformation, causing the coal rock mass to fracture and forming a fan-shaped coal fall.
Technical approaches to improve the performance of cutting teeth
1. Development of impact resistant, wear-resistant, and crack free hard alloy cutting heads. In the field of hard alloy research, we collaborated with Zhuzhou Hard Alloy Factory to conduct research on hard alloys. Through anatomical analysis of domestic and foreign hard alloy cutting heads, it is found that the three properties (magnetic force, specific gravity, and hardness) of foreign alloys and domestic alloys are basically similar. It is also difficult to see a significant difference between the two in the microstructure of the alloy. However, the impact resistance and wear resistance of foreign cutting heads are significantly better than those of domestic cutting head alloys, mainly due to the low purity of domestic cutting head alloy raw materials and outdated powder forming processes. Therefore, research was conducted on new materials and processes for hard alloys. The developed cutter head uses raw materials, improves the forming process and alloy production process (high-purity tungsten powder, high-temperature reduction, high-temperature carbonization), and other three technical measures to improve the service life of the cutter head. The developed alloy has high toughness, wear resistance, and impact resistance.
Hardfacing of 2 wear-resistant layers
In order to solve the problem of rapid wear and failure of the cutting teeth during the coal mining process, a welding method (or other metallurgical methods) is used to weld a circular belt with a width of about 20-30mm and a thickness of 2-3mm along the circumferential direction below the tooth body of the cutting tooth cone (hard alloy cutting head). This annular strip is called a wear-resistant overlay layer. Common wear-resistant welding materials include martensitic welding alloys (D317, D327, DG7, etc.), high chromium Fe-Cr-C alloy systems (D688, D638, etc.), tungsten carbide, niobium carbide (Beijing Guben brand KB515), etc. Mechanistically speaking, the function of the wear-resistant welding layer on the cutting edge is to compensate for or change the performance degradation phenomenon formed by the brazing process of the hard alloy cutting edge on the circumference of the tooth body (referring to the cutting edge produced by the first heat treatment and then brazing process). 2. Further optimize or enhance the performance of the blade section. Of course, when using the manufacturing process of brazing the cutting head first and then overall heat treatment of the cutting teeth, the latter plays a more prominent role. However, the actual situation is not simple. The emergence and use of wear-resistant welding layers on cutting teeth convert the friction and impact between the cutting edge and the cut coal rock into or partially into the friction and impact between the welding layer and the cut coal rock. The friction, wear, and impact damage between them not only depend on the characteristics and matching behavior of the two contact materials, but also are influenced by many factors during the coal mining process.
Research on the Material of Three Knife Bodies
At present, the material used for the cutter body of domestic tunneling machines is mostly alloy structural steel 35CrMnSiA. This material has high comprehensive mechanical properties after quenching and low-temperature tempering or isothermal quenching, but its transverse performance is worse than its longitudinal performance, and it has obvious defects such as tempering brittleness. For this purpose, research was conducted on using 42CrMo alloy structural steel as the cutting material. 42CrMo also belongs to medium quenched and tempered alloy steel, which has no tempering brittleness. After quenching and tempering, it has higher fatigue and resistance to multiple impacts. Compared with 35CrMnSiA alloy steel, it is more suitable for the stress characteristics of cutting teeth. The test results show that the crack resistance and impact toughness of the tooth body head made of this steel are better than those of 35CrMnSiA steel. Therefore, 42CrMo alloy structural steel is more suitable as a cutting material than 35CrMnSiA alloy structural steel.
Research on the gap between 4 weld seams
The size of the gap between the cutting teeth brazed weld seam is a key factor affecting the density and strength of the weld seam. The gap is too small, which hinders the flow of brazing material; Excessive gap disrupts the capillary action of the brazing seam, preventing the brazing material from filling the gap of the weld seam. The brazing of cutting teeth is a welding of dissimilar materials between steel and hard alloy, considering that the linear expansion coefficient of hard alloy is 1 of steel Π 2~1 Π 3. Therefore, the gap between brazing seams should be slightly smaller than when welding steel to steel.