High-speed cutting applicability
The advantages of high-speed machining as a new technology are obvious, and it brings a revolutionary change to the traditional metal cutting theory. So, is it all-inclusive? Obviously not. At present, even in the advanced level of metal cutting machine tools in Switzerland, Germany, Japan, the United States, the research on this new technology is still in the process of continuous exploration. In fact, people have little experience in high-speed cutting, and there are still many problems to be solved: such as the dynamic and thermal characteristics of high-speed machine tools; tool materials, geometric angles and durability issues, interface technology between machine tools and tools. Dynamic balance, torque transmission, selection of cooling lubricant, post-processing problems in CAD/CAM, optimization of tool path during high-speed machining, etc. So far, the current domestic real use in the actual processing is the Swiss MIKRON company's spindle speed of 42000r / min machine tool, Nanjing University of Aeronautics and Astronautics bought MIKRON spindle 18000r / min machine tool, Shanghai Jiaotong University, Dalian University of Technology, etc. also bought For machine tools with a spindle speed of 18000r/min, Shandong University of Technology, Xi'an Jiaotong University, and Beijing Institute of Technology will purchase high-speed machine tools for corresponding research. It should be said that high-speed cutting in China has not yet officially entered the university classroom. If some professors and mentors are still blank in their minds, how can they teach students and develop corresponding technologies? Not to mention the situation of domestic machine tool manufacturers. It should be realistically said that due to the small amount of scientific research investment by state-owned enterprises over the years, the existing mechanisms cannot fully encourage innovation, the basic research and components are weak, and the development of new products lags behind, and so on. China's machine tool industry and foreign counterparts in the same industry. The gap in the level has widened, and this gap is generally more than a decade.
It now appears that high-speed cutting with a spindle speed of 10 to 42000 r/min is still subject to some limitations in practical applications:
(1) When the spindle speed is 10~42000r/min, the tool must use HSK tool holder, plus dynamic balance, the length of the tool can't exceed 120mm, the diameter can't exceed 16mm, and the imported tool must be used. This is limited when performing deep cavity machining.
(2) When the machine tool is equipped with an electric spindle with a rotational speed of 10 to 42000 r/min, the torque is extremely small, usually only a dozen N·m, and the maximum speed is only 5-6 N·m. Such high-speed cutting can generally be used for finishing graphite, aluminum alloy, and quenching materials.
(3) MIKRON developed some machine tools with spindle speeds of 12000r/min, 15000r/min, 18000r/min and 24000r/min for these situations, and tried to increase the feed rate (40000～6000mm/min) to ensure the machine tool It can carry out roughing and finishing, which saves time and efficiency.
(4) For the traditional processing methods and different materials to be cut, the appropriate tool materials should be selected to achieve high-speed machining, and high speed and high speed can not be pursued blindly. For example, in the aerospace industry in the United States, it is possible to achieve a linear speed of 7500 m/min to cut aluminum alloys; but when cutting steel and cast iron, the highest speed that can be achieved by the actual high-speed machining in the world can only reach the processed aluminum. 1/3 to 1/5 of the alloy is about 1000 to 1200 m/min. The reason is that the heat of cutting causes thermal damage to the tip. It can be seen that the heat resistance of the tool material is the key to processing ferrous metals. For superalloys, including nickel-based, cobalt-based, iron-based, and titanium-based alloys, the common feature is high strength and high corrosion resistance at high temperatures, but they are all difficult to machine materials. The current feed rate for this material is currently 500m/min, which is mainly influenced by the tool material and its geometry.
Therefore, the tool material for high-speed machining must be selected according to the material of the workpiece and the processing properties. In general, ceramic (AlO, SiN), cermet and PCBN tools are suitable for high-speed machining of ferrous metals such as steel and iron; tools such as PCD and CVD are suitable for high-speed machining of non-ferrous metals such as aluminum, magnesium and copper. .
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