In addition to the mechanical clamping and bonding method, the PCD composite sheet and the cutter body are mostly pressed on the cemented carbide substrate by brazing.
The welding methods mainly include laser welding, vacuum diffusion welding, vacuum brazing, high frequency induction brazing, etc. At present, high-frequency induction heating brazing PCD cutting tool blade welding with low investment and low cost is widely used.
The blade welding process, welding temperature, and selection of flux welding alloy will directly affect the performance of the tool after welding. In the welding process, the control of welding temperature is very important. If the welding temperature is too low, the welding strength will be insufficient; if the welding temperature is too high, the PCD will be easily graphitized, which may lead to "overburning", which will affect the combination of the PCD composite sheet and the cemented carbide substrate.
In the actual processing process, the welding temperature can be controlled according to the degree of reddening of PCD during the holding time (generally should be lower than 700 ℃). Foreign high-frequency welding mostly adopts automatic welding process, which has high welding efficiency and good quality, and can realize continuous production; in China, manual welding is mostly used, which has low production efficiency and unsatisfactory quality.
The high hardness of PCD makes its material removal rate extremely low (even only one ten thousandth of the removal rate of cemented carbide).
At present, the PCD cutting tool sharpening process mainly uses resin-bonded diamond grinding wheels for grinding. Due to the interaction between the grinding wheel abrasive and PCD grinding two materials with similar hardness, the grinding law is more complicated.
For high-grain, low-speed grinding wheels, the use of water-soluble coolant can improve PCD grinding efficiency and grinding accuracy. The choice of grinding wheel bond should depend on the type of grinding machine and processing conditions.
Since the electrical discharge grinding (EDG) technology is hardly affected by the hardness of the workpiece being ground, the use of EDG technology to grind PCD has great advantages. The grinding of certain complex-shaped PCD cutting tools, such as woodworking tools, also has a huge demand for this flexible grinding process. With the continuous development of EDM grinding technology, EDG technology will become a major development direction of PCD grinding.
PCD is not only an engineering material, but also a new type of functional material; it is a high-tech product and a high-efficiency product. With the development of modern industry and science and technology, polycrystalline diamond has been widely used in modern industry, national defense and high-tech fields due to its excellent mechanical, thermal, chemical, acoustic, optical, electrical and other properties.