Gold cutting foundation: tool material and tool construction
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One type is tungsten drills (YG type) composed of WC and Co; the other is tungsten titanium drills (YT type) composed of WC, TiC and Co.
YG-based hard alloys have good toughness, but when they are used to cut tough materials, they have poor wear resistance, so they are suitable for processing brittle materials such as cast iron and bronze.
Commonly used grades are YG3, YG6, YG8, etc., where the number indicates the percentage of Co content. Less Co content, more brittle and more wear-resistant.
YT type cemented carbide has higher hardness and better heat resistance than YG type, and is more wear-resistant when cutting tough materials, but has less toughness, so it is suitable for processing steel parts.
Commonly used grades are YT5, YT15, YT30", etc., where the number indicates the percentage of TiC combination. The more TiC content, the lower the toughness, and the higher the wear resistance and heat resistance.
(5) Ceramic materials
Its main component is Al2O3. The blade has high hardness, good wear resistance and high heat resistance. It allows high cutting speed, and the price of Al2O3 is low. The raw materials are rich, so it has a promising future.
However, the ceramic material is brittle and shocked, and it is easy to chip when cutting. The cermets made in China, such as AM, AMF, AMT, AMMC, etc., contain various metal elements in addition to Al2O3, and the flexural strength is higher than that of ordinary ceramic blades.
3. Introduction of other new tool materials
(1) Improvement of high speed steel (2) Improvement of cemented carbide (3) The hardness of synthetic diamond is close to 10000 HV, and the hardness of cemented carbide is only 1000 to 2000 HV, and the heat resistance is 700 to 800 °C. The large polycrystalline diamond particles can be made into a general cutting tool, and the single crystal particles are mainly made into a grinding wheel.
In addition to processing high hardness and wear-resistant cemented carbide, ceramics, glass, etc., diamond can also process non-ferrous metals and their alloys.
Diamond is not suitable for processing iron group metals. This is due to the strong affinity of iron and carbon atoms, which tends to cause bonding to accelerate tool wear.
(4) Cubic boron nitride (CBN) hardness (7300 ~ 9000HV) is second only to diamond. However, its heat resistance and chemical stability are much higher than that of diamond, it can withstand high temperatures of 1300 to 1500 ° C, and has a low affinity with iron-based metals. Therefore, its cutting performance is good, not only suitable for the processing of non-ferrous hard-to-machine materials, but also for the processing of iron-based materials. CBN and diamond tools are brittle, so the machine tool is rigid when used, mainly for continuous cutting, to avoid shock and vibration.
Second, the tool angle
Although there are many types of cutting tools, the structural elements and geometric angles of the cutting parts have many features in common. As shown, various multi-tooth or complex tools, in terms of one tooth, are equivalent to the head of a turning tool.
Start with the turning tool for analysis and research.
1. The composition of the cutting part of the turning tool
The cutting part of the turning tool is composed of three cutting faces, namely the rake face, the main flank face and the minor flank face.
(1) The surface on which the chips flow on the rake face cutter. (2) The surface of the flank cutter opposite the surface produced in the cutting on the workpiece. Main flank face: intersects with the rake face to form the flank face of the main cutting edge. Secondary flank face: intersects with the rake face to form the flank face of the minor cutting edge. (3) Cutting edge
The cutting edge refers to the edge to be used for cutting on the rake face of the tool, and has the main cutting edge and the minor cutting edge.
The major cutting edge is the point at which the primary yaw angle at the cutting edge is zero and at least one segment of the cutting edge that the cutting edge is intended to cut the transition surface on the workpiece. When cutting, the main cutting work is borne by it.