Diamond abrasives are special tools for grinding cemented carbide. Its biggest success is the diamond resin grinding wheel and bronze grinding wheel grinding carbide tools, promote the process of carbide tools; At the same time, it is also suitable for grinding cemented carbide measuring tools, molds, fixtures and other cemented carbide workpieces. The grinding ability of diamond to carbide is thousands of times higher than that of silicon carbide. When grinding carbide turning tools, each 1g of metal needs to consume 4-15g green silicon carbide abrasive, while diamond only consumes 2-4g. Diamond grinding wheel grinding cemented carbide than ordinary grinding wheel grinding ratio is thousands of times higher, the cost is reduced by more than 10%. Diamond grinding wheel grinding carbide tool, can avoid the silicon carbide grinding wheel processing prone to cracks, cracks and other defects, the machining tool roughness and accuracy is high, the tool life can be extended by 50%-100%, and can save the polishing process after grinding, production efficiency can be increased several times. When grinding alloy tool steel with diamond grinding tool, the grinding ratio is more than 10 times higher than that of ordinary grinding wheel, the cost is reduced by 10%, and the burn phenomenon easily caused by ordinary grinding wheel is avoided. However, it should be pointed out that for grinding alloy tool steel, cubic boron nitride grinding tool should be the preferred tool, it is more advantage than diamond grinding tool, for high-speed and efficient grinding and honing processing, can greatly improve the grinding efficiency, its grinding accuracy and quality improve a grade.
With the development of diamond and cubic boron nitride composite materials PCD(polycrystalline diamond tool composite sheet) and PCBN(polycrystalline cubic boron nitride), the use of PCBN tool processing hardened steel, the workpiece hardness is higher than 50HRC, the effect is better. The cutting speed is generally 80 ~ 120m/min, the higher the hardness of the workpiece, the lower the cutting speed, such as the workpiece hardness of 70HRC, the cutting speed should be selected 60 ~ 80m/min. The cutting depth of the fine turning is 0.1 ~ 0.3mm, the feed is 0.05 ~ 0.025mm/r, the surface roughness of the workpiece after the fine turning is Ra0.3 ~ 0.6μm, and the dimensional accuracy can reach 0.013mm. If the standard CNC lathe with good rigidity can be used, the rigidity of the PCBN tool is good and the cutting edge is sharp, the surface roughness of the workpiece after the fine turning can reach Ra0.3μm, the dimensional accuracy can reach 0.01mm, and the level of processing with the CNC grinder can be reached. If the machine rigidity is good and the cutting speed is low, the PCBN composite blade can be used to fine turn the interrupted surface. The fine turning processing allowance is generally about 0.3mm, and the dimensional accuracy of the workpiece before quenching is improved as much as possible and the thermal deformation is reduced, so as to ensure the uniform cutting allowance during the fine turning and extend the service life of the PCBN tool. Fine turning generally does not use cutting fluid, because at a higher cutting speed, a large amount of cutting heat is taken away by the chips, and rarely stays on the surface of the workpiece and affects the quality and accuracy of the machining surface. The fine turning blade should be 80° diamond-shaped blade with high strength and toughness, and the radius of the tip is between 0.8 and 1.2mm. In order to protect the cutting edge of the tool, it is necessary to use a fine stone chamfering before use. Fine turning hardening workpiece is a new process, before the implementation of the need to do the process test, can be used with the workpiece material, hardness and size of the same bar, in the same machine tool for finishing or roughing test, the key is to test the choice of cutting tools and cutting parameters and whether the process system has enough rigidity. The process has been adopted in China, such as FAW Group with PCBN tool processing carburized quenching (58 ~ 63HRC) 20CrMnTi transmission gear fork groove, the use of process parameters Vc=150m/min,f=0.1mm/r, ap=0.2 ~ 0.3mm, to achieve the car instead of grinding. When using PCBN tool to process hard cast iron, as long as the hardness reaches the medium hardness level (45HRC), good processing results will be achieved. Such as the exhaust valve seat on the cylinder head of the automobile engine, the valve seat is made of high chromium alloy cast iron material containing copper and molybdenum, its hardness is generally about 44HRC, and the valve seat holes are sunk (reamed) and the car two processes, mostly processed on the special automatic line, and the gun reamed pipe holes are carried out together. The cutting parameters used are: Vc=71.6m/min, Vf=26.5mm/min, ap=1.0mm, using BC broach oil, since the use of PCBN tool processing, compared with the previous use of various cemented carbide blade processing, the average durability of the tool is 1200 pieces, the machining surface roughness is Ra0.4μm, the seat surface swing difference is less than 0.05mm. Since 1988, the engine plant of Dongfeng Motor Company has used PCBN tools, and its effect has remained stable, which has better solved the problem of localization of tools introduced into the equipment. With the rapid development of China's automobile manufacturing industry, the domestic tool industry is also extremely active and thriving.
Our JMD synthetic diamond fine material, diamond crushing material, diamond micro powder, cubic boron nitride CBN, cubic boron nitride micro powder, polycrystalline diamond PCD, polycrystalline cubic boron nitride PCBN are widely used in metal processing, mechanical processing and automotive industry and other fields.
