The choice of high-speed cutting tool

The high-speedcutting tools (High-Speed ​​Machining, HSM) is to move rapidly in the 1990s, the practical application of advanced processing technology, usually refers to vertical milling under high spindle speed and high feed rate, international processing industry in the aerospace manufacturing industry, mold , car zero Shijia workers, as well as precision zero Shijia workers, and other fields are widely used. High-speed milling can be used for cutting, such as aluminum, copper metal and hardened steel, titanium alloys, high temperature alloys and other difficult-to-machine materials, as well as carbon fiber, plastic and non-metallic materials processing. For example, in the processing of aluminum alloy aircraft parts, surfaces and complex structure, material removal as high as 90% -95%, the use of high-speed milling everyone to improve production efficiency and precision. The high-speed cutting tool technology is one of the key technologies to achieve high-speed machining. With the substantial increase in cutting speed cutting tool material and geometric parameters, arbor structure and cutting process parameters are different from the requirements of the traditional speed cutting right choice and optimization of the parameters of the tool, to improve processing efficiency and quality to extend tool life, reduce processing costs will play a very critical role.

1 tool material

  High-speed milling tool materials carbide coated tools, cermet, ceramics, cubic boron nitride (CBN) and diamond tools.

  Carbide: high-speed cutter usually fine grain products or ultrafine grain products Carbide the (product grain size of 0.2 ~ 1 μ m), selected according to the material to be machined tungsten cobalt carbide or tungsten titanium cobalt classes.

  Coated tools: a large number of high-speed milling of coated tools, matrix high speed steel, carbide rain I ceramic, carbide mainly. TiCN, TiAIN, TiAICN, CBN, Al2O3, CNx coating material, commonly used multi-layer composite coating, such as: TiCN + Al2O3 + TiN, TiCN + Al2O3, TiCN + Al2O3 + HfN, TiN + Al2O3, TiCN, TiB2 , TiAlN / Tin and TiAlN. Latest development TiN / AIN nano-coated tools are also suitable for high-speed cutting.

  Cermets: high wear resistance of TiC-based cermet (TiC + Ni or Mo). High toughness of TiC-based cermet (TiC + TaC + WC + Co), Enhanced TiCN based cermet (TiCN + NbC), compared Carbide improve the high temperature properties of the tool, suitable for high-speed machining alloy steel and cast iron.

  Ceramic Tool: ceramic tool is divided into alumina ceramics, silicon nitride ceramics, and composite ceramics of three types, having a high hardness, high wear resistance, thermal stability. Al2O3 ceramic accounts for about 2/3, this ceramic tools for machining steel; about 1/3of Si3N4-based ceramic, this ceramic tool is more suitable for high-speed milling of cast iron; Si3N4-Al2O3 composite ceramics with high strength and fracture toughness, is not suitable for the machining of steel, can be used for high speed roughing of cast iron and nickel-based alloys.

CBN: CBN tool has a high hardness, high heat resistance, high chemical stability and thermal conductivity, but with lower intensity. Score by weight, low content of CBN (50% ~ 65%) can be used for the finishing of hardened steel; high content of CBN (80% ~ 90%) can be just high-speed milling of cast iron, hardened steel roughing and semi-finishing .

  Diamond: points natural diamond and polycrystalline diamond, high-speed milling of polycrystalline diamond, usually used for high-speed processing of non-ferrous metals and non-metallic materials.

  High-speed milling, the most widely used solid carbide cutting tools, followed by machine clip carbide cutting tools.

2 tool structure

Figure 1 is a typical high-speed milling tool

  Figure 1 shows some typical high-speed milling cutter is divided into two types, the overall style and machine folder. Small diameter cutters generally use a whole large diameter cutter machine clip. High-speed machine tool diameter limit, the overall high-speed cutter in the factory after the balancing test, use more convenient machine clip after clamping the blade dynamic balance, so the overall style of the more common. The machine is relatively low speed, can be used to provide greater torque machine clip cutter. Balance Grade clip cutting tools in high speed machine, it should be noted that the tool, as well as the maximum allowable speed.

  Cutter pitch is defined as adjacent to the periphery of the two knife between the teeth to the distance, is influenced by the number of teeth of the cutter knife. Means more short pitch cutter tooth-and middle-chip space, allowing high metal removal rate, generally used for cast iron milling and milling medium load steel, usually as a high-speed cutter preferred. Large pitch cutter teeth less chip space, commonly used for roughing and finishing of steel, and prone to vibration occasions. Small the superdense pitch chip space, can withstand very high feed rate, suitable cast iron intermittent surface processing, the small cut cast iron roughing and steel deep processing.

3 shank structure

  Usually when the maximum speed of the machine to achieve 15000r/min HSK high-speed cutter arbor, or other types of short handle Arbor. HSK shank for positioning structure, providing links to the machine tool standard machine under tension, to ensure Arbor short cone and end face close coordination with the machine.

  Arbor clamping tool side with spring clamp type, hydraulic clamping and thermal expansion type, Weldon is difficult to guarantee Cutter balance should not be used in high-speed milling. Figure 2 for the elastic clamping, hydraulic clamping and thermal expansion Arbor schematic diagram. Thermal expansion structure is simple, reliable clamping, high concentricity transfer torque and radial force, rigid foot, balancing arbor structure is currently the most development potential.

Figure 2 arbor chuck the form

  Knife hole and shank of thermal expansion Arbor chuck interference fit, to adopt the the dedicated thermal expansion device handling tool, the general use of the inductive heating or hot air heating Arbor knife holes true diameter expansion, and then insert the knife handle knife After cooling aperture contraction to grip the knife handle. The above three tool clamping manner, the clamping of the tool to the thermal expansion the highest mounting precision, while providing more fire torque. Especially in the application of a small-diameter tool for high speed machining, thermal expansion, clamping advantages.

4 processing technology and cutting parameters

  Is generally not recommended in high-speed milling end mills using flat-bottomed. This is because the flat bottom end mill cutting tool tip site to the chip flow interference chip deformation, while the shortest effective length of the cutting edge, the tool nose fire by force, cutting temperature, resulting in rapid wear. Larger tool nose radius should make salmon under the conditions of the process allows for high-speed milling, because the average cutting thickness and main angle decreased with increasing the corner radius end mill, at the same time the tool increased axial force can take full advantage of the axial stiffness of machine tools to reduce tool vibration deformation and cutting.

  Therefore, commonly used in high-speed milling larger corner radius end mills (ball end cutters or circular blade mosaic tool), and axial depth of cut is generally not to declare more than the nose radius. Related to the radial depth of cut material selection and processing can be used to improve processing efficiency, light alloy of aluminum like the larger radial milling depth, and somewhat less for steel and other processing materials should choose smaller radial The milling depth slowing tool wear.

  The determination of the amount of high-speed milling machining efficiency is the main consideration, the machined surface quality, tool wear, as well as processing costs [5]. Different tool machining different workpiece material, processing and consumption vary significantly, the No complete processing data. High-speed milling in aluminum processing technology is more mature, generally based on the actual selection of cutting tools and machining object reference tool vendor processing the amount of choice. The general election express the principles of the medium to the amount of feed per tooth fz, smaller axial depth of cut ap appropriate radial depth of cut ae maintain high cutting speed and spindle speed.

5 Conclusion

  High-speed machining is the inevitable trend of development of the mechanical manufacturing industry to accelerate its marketing application will create huge economic benefits. The high-speed cutting tools technology has decisive for the development and application of high speed cutting technology Chuan, therefore, the research and development of high-speed cutting tool technology has great significance. With the development of advanced manufacturing technology and materials technology, coated tools, superhard material tools, ceramic tools will be widely used, the system of high-speed cutting tools are maturing, becoming an important part of promoting high-speed machining.

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