Metal bond diamond grinding wheel according to the different manufacturing methods are mainly two types of sintered plating. In order to give full play to the role of superhard abrasive, foreign countries began to develop a new type of grinding wheel with high-temperature brazing technology from the early 1990s, namely a single-layer high-temperature brazing superhard abrasive grinding wheel. At present, this type of grinding wheel is still in the research and development stage.
Sintered Diamond Grinding Wheel Sintered metal bonded grinding wheels are mostly made of bronze and other metals as bonding agents. They are manufactured by high-temperature sintering. They have high bonding strength, good moldability, high-temperature resistance, good thermal conductivity, and long service life. Larger load. Because the grinding wheel inevitably retains shrinkage and deformation, the wheel must be shaped prior to use, but it is difficult to dress the wheel. At present, the commonly used grinding wheel roll-to-roll shaping method not only takes time and labor to trim but also has more diamond particle shedding during the dressing process. The dressing wheel itself consumes a lot and the shaping accuracy is low.
In recent years, scholars from various countries have successively carried out research on the application of special processing methods to trim metal bonded diamond grinding wheels, mainly including electrolytic dressing and electric spark dressing and compound dressing. Electrolytic trimming method is fast, but the precision of plasticity is not high; EDM trimming method has high orthopedic precision and can be both plastic and sharp, but the shaping speed is slower; composite trimming method includes electrolytic spark composite trimming method and mechanochemical composite trimming method. Such as dressing effect is good, but the system is more complex, so the problem of sintering diamond grinding wheel dressing has not been well resolved.
In addition, because the grinding wheel manufacturing process determines the surface morphology is random, the geometry, distribution, and height of the cutting edge of each abrasive are inconsistent, so only a few high cutting edges are cut to the workpiece during grinding, which limits the grinding quality of grinding. The efficiency is further improved.
Electroplated Diamond Wheel Electroplated Diamond Wheel Advantages:
1 The plating process is simple, less investment, easy to manufacture;
2 No need to trim, easy to use;
3 The single-layer structure determines that it can achieve high working speeds, and it is currently up to 250-300 m/s in foreign countries;
4 Although there is only a single layer of diamond, there is still enough life;
5 For high precision roller wheel, the only manufacturing method of plating.
Because of these advantages, high-speed, ultra-high-speed grinding of electroplated grinding wheels occupies an undisputed dominant position. Electroplated diamond grinding wheel defects: There is no strong chemical and metallurgical bonding between the coating metal and the substrate and the abrasive bonding surface. The abrasive is actually only mechanically embedded and embedded in the plating metal, so the holding force is small, the diamond particle load is heavy and the grinding is easy and efficient. (or coating stripping off) causes overall failure; to increase the holding force, it is necessary to increase the thickness of the coating. As a result, the height of the exposed abrasive grains is reduced, the grinding wheel is easily clogged, the heat dissipation effect is poor, and the surface of the workpiece is prone to burn. At present, the domestic manufacture of electroplated grinding wheels has not been optimized to design the best geomorphology of the grinding wheel according to the processing conditions. The inherent disadvantages of single-layer electroplated diamond grinding wheels will inevitably limit its effective grinding applications.
Single-layer brazing diamond grinding wheels In order to give full play to the role of diamond, it is necessary to increase the holding power of the bonding agent to the diamond and increase the bonding strength of the grinding wheel. The single-layer high-temperature brazing superhard abrasive wheel can overcome the defects of the electroplated grinding wheel and can achieve chemical metallurgical bonding between the diamond, binder, and metal matrix, and has high bonding strength, and only needs to maintain the thickness of the bonding layer to maintain the height of the abrasive particles by 20%. ～30% can use high-speed and high-efficiency grinding to firmly hold the abrasive grains, making the exposed height of the brazed grinding wheel abrasive grains reach 70% to 80%, thus increasing the chip space, preventing the grinding wheels from clogging, and making full use of abrasive materials.
Under the same processing conditions as the electroplated grinding wheel, the single-layer high-temperature brazing super-abrasive grinding wheel has lower grinding power, power loss, and lower grinding temperature, which means that higher working speeds can be achieved. This ultra-high speed grinding of 300-500 m/s or more Has a special significance. Single-layer high-temperature brazing non-coated diamond grinding wheel plus Cr silver base brazing single-layer brazing grinding wheel using high-frequency induction brazing method, with the addition of Cr Ag-Cu alloy as the brazing material, brazing at 780°C for 35 s, natural cooling, A solid connection between the diamond and the steel substrate can be achieved. The X-ray energy spectrum and X-ray diffraction analysis showed that Cr3C2 formed between Cr and diamond and (FexCry)C formed between the steel and the matrix. The comparison experiments with and without Cr brazing showed that this achieved the alloy layer with diamond and steel. The main factors of high bonding strength between the matrix and the fact that the diamond has a high holding strength are verified through grinding experiments.
