Common PCD cutting tools grinding processes include diamond wheel mechanical grinding, EDM grinding, electrolytic grinding, etc. Among them, diamond wheel mechanical grinding is the most mature in technology and the most widely used. Although this method has a lower grinding efficiency and higher processing costs, it can obtain good tool cutting edge quality and complete, smooth front and back surfaces.
The material removal mechanism of diamond wheel mechanical grinding PCD cutting tools is relatively complex, and domestic and foreign scholars have conducted extensive research on this, and there are currently mainly the following viewpoints:
German scholar M.Kenter believes that during the grinding process of diamond wheel grinding PCD cutting tools, there is scratching and sliding action, and the material removal method mainly includes bonding, scratching, friction chemical reactions, and surface fracture. He believes that in most cases, the removal of PCD material is mainly by friction chemical reactions and surface fracture.
Since PCD material is brittle, it is prone to induce cracks under the squeezing of diamond abrasive grains, and cracks expand under mechanical and thermal stress, ultimately resulting in small pieces of PCD material peeling off. At the same time, friction heat will cause PCD to undergo graphitization and other friction chemical reactions.
K.J.Dunn and others from GE Company used scanning electron microscopy to observe the surface morphology of the ground PCD composite sheets and concluded that the destruction mechanism of PCD material was mainly micro-brittle fracture and fatigue damage.
The removal method of PCD material is: when the grinding wheel contacts with PCD, the grinding force suddenly increases, and the violent mechanical impact causes cracks or even breakage on the PCD surface. In the stable grinding period, the abrasive grains of the grinding wheel are pressed and rubbed on the PCD surface. When the pressure reaches a certain degree, cracks will form on the PCD surface. When the friction temperature reaches a certain degree, PCD will undergo graphitization and other chemical reactions.
The characteristics of PCD materials determine the requirements for PCD cutting tool grinding machines: they cannot be equivalent to ordinary tool grinders, that is, they must meet the following conditions:
The grinding wheel spindle and the machine tool as a whole must have high rigidity and stability to maintain a constant pressure of the grinding wheel on the PCD material during grinding.
The grinding wheel frame can swing laterally to ensure uniform wear of the end face of the grinding wheel. The swing frequency and amplitude of the grinding wheel frame can be adjusted.
Equipped with optical projection device and high-precision rotary worktable.
Use a special diamond grinding wheel.
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