In grinding, the use of superhard abrasive wheels is very common. However, in order to ensure the accuracy and quality of grinding products with superhard abrasive wheels, certain requirements need to be made for superhard abrasive wheels in machining. Superhard abrasive wheels need to reduce vibration, improve machining stability, and avoid machining surface quality and dimensional accuracy errors. Then, what are the requirements for the use of superhard abrasive wheels?
Requirements for the use of superhard abrasive wheels
1. The rotation accuracy of the grinding wheel spindle is high. Generally, the axial runout is less than 0.005mm and the radial runout is less than 0.01mm.
2. The grinder should have enough rigidity, which is required to be about 50% higher than that of ordinary grinder. When the static stiffness of the machine tool is increased by 20%
The service life of the grinding wheel can be increased by more than 50%.
3. The sealing of the grinder must be reliable, especially the sealing of the headstock spindle and bearing.
4. The accuracy of the feeding mechanism of the grinder should be high, and it should ensure that it is fed evenly and accurately, stable and free of movement, with less than 0.005mm times
Feed mechanism.
5. The grinding machine shall be provided with shockproof measures.
2、 Grinding fluid selection requirements
In addition to the general grinding requirements for grinding fluid, the particularity of the grinding wheel itself should also be considered in superhard abrasive wheel grinding. Compared with ordinary grinding wheels, its hardness is high, its structure is dense, its pores are few, and it is easy to be blocked in the grinding process. It requires that the grinding fluid has good wettability and cleaning, and its viscosity is small. When using resin bonded grinding wheel, wet grinding can reduce the grinding temperature and reduce the thermal decomposition of the bond near the abrasive particles. Compared with dry grinding, wet grinding can increase the service life of the grinding wheel by about 40% and improve the quality of the machined surface.
The grinding fluid for diamond grinding wheels is usually kerosene with strong washability, or light diesel oil or a 1:10 mixture of low-grade machine oil and kerosene. Various water-soluble grinding fluids and weak alkaline emulsions can also be used. Among them, kerosene, diesel oil and water-soluble grinding fluid are better. For example, kerosene is widely used in grinding cemented carbide. If there is a large smoke during grinding, mixed aqueous solution can be used, but emulsion should not be used. Soda water and strong alkaline emulsion should not be used for resin bonded grinding wheel. Its pH should not exceed 9 and the liquid temperature should not exceed 30 ℃.
The EP oil grinding fluid used in profile grinding, thread grinding and gear grinding has good effect, which can correspondingly improve the quality of the machined surface, shallow grinding scoring lines, and increase the service life of the grinding wheel.
CBN grinding wheels generally do not use water-soluble grinding fluid, but mostly use light mineral oil (kerosene, diesel, etc.). CBN abrasive particles will react with water at high temperature, which is called hydrolysis, which intensifies the wear of abrasives. When aqueous solution is necessary, extreme pressure additives should be added to reduce hydrolysis.
If the dry grinding process is adopted for superhard abrasive wheels, the binder and particle size should be appropriately selected, and the back cutting amount and feed amount should be reduced to reduce the grinding temperature.
The use requirements of these superhard abrasive wheels need to be strictly observed during grinding. In the process of grinding, it is easy to produce errors due to some external environment. Therefore, processing according to regulations is one of the effective methods to reduce errors and ensure product accuracy.