Cemented carbide is made of high hardness, refractory metal carbide (such as WC, TiC, TaC, NbC, etc.) plus metal binders (such as cobalt, nickel, etc.) through powder metallurgy process, it is currently the world's highest strength alloy, with high hardness (89~93Hm), high strength, good hot hardness and other characteristics. Therefore, it is widely used in the manufacture of exploration drill bits, molds and tools. With the continuous development of cutting technology in the direction of high speed and high precision, the hardness, wear resistance, grinding accuracy and cutting edge quality of cemented carbide tools are required to be higher and higher. The grain size of cemented carbide has also gradually developed from the initial coarse-grained and medium-grained to fine-grained, ultra-fine-grained and nanocrystal-grained.
At present, coarse-grained cemented carbide is widely used in geological and mineral tools, stamping dies, oil drilling, large top hammers for the production of synthetic diamond, jet engine parts and other fields; fine-grained and ultra-fine-grained cemented carbide has the characteristics of high hardness and high strength, it is mainly used for the manufacture of solid carbide tools, indexable inserts and micro drills.
With the refinement of WC grains in cemented carbide, the mechanical properties such as hardness and strength increased, meanwhile the properties such as fracture toughness decreased, and the grinding performance such as wear resistance also changed.
Three different grain size diamond resin bond grinding wheels are used to carry out grinding tests under certain grinding conditions for three cemented carbides with different grain sizes: coarse, fine and ultra-fine. Through the measurement of the spindle power, grinding wheel and workpiece loss, and machining surface roughness of the surface grinder during the grinding process, the influence of the grain size change of WC in cemented carbide on the grinding performance and effect such as grinding force, grinding ratio, and surface roughness is analyzed.
Through the test, it can be known that under the condition, the grinding parameters of the surface grinder are the same, the grinding force and grinding energy consumed by grinding coarse-grained cemented carbide are greater than those of fine-grained and ultra-fine-grained, and the grinding force of the surface grinder increases with the rising of grain size. The grinding ratio of ultra-fine cemented carbide increases with the rising of grain size, indicating that the wear resistance of this kind of cemented carbide decreases with the increase of grain size, and the surface roughness of this kind of cemented carbide after fine grinding under the same grinding conditions decreases with the increase of grain size.
Using diamond grinding wheel is the main method for the production of cemented carbide tools, the grinding surface roughness has an important impact on the cutting performance and service life of cemented carbide tools, and the grinding parameters are the main factors that affected the surface roughness of cemented carbide
The WC-Co cemented carbide specimen was subjected to grinding test on a surface grinding machine, and the specimen was an ultra-fine-grained cemented carbide sintered by HIP technology.
At the same depth, the roughness of the grinding surface of the specimen increased with the rising of the particle size of the grinding wheel. Compared with the 150# grinding wheel, the surface roughness of the sample grinding varies less when grinding with a 280# grinding wheel, while the surface roughness changes more when grinding with a W20 grinding wheel.
Post time: Jan-25-2024