The function of the hottest dry cutting in gear ma

The role of dry cutting in gear machining

the key to the role of dry cutting in gear machining is to find a way to replace cooling and lubrication. At present, there are two successful dry cutting methods: high-speed dry cutting and low-temperature cold air cutting

I. high speed dry cutting and low temperature cold air cutting

high speed dry cutting method

this processing method uses a very high cutting speed without the action of cooling and lubricating agents. Proper cutting conditions must be selected for dry cutting. First, use a high cutting speed to minimize the contact time between the tool and the workpiece, and then remove the chips with compressed air or other similar methods to control the temperature of the working area. With the extensive use of numerical control technology, the rigidity and dynamic performance of machine tools continue to improve. It is not difficult to improve the cutting speed of machine tools. Practice has proved that when the cutting parameters are set correctly, 80% of the heat generated by cutting can be taken away by chips

high speed dry cutting method has strict requirements for the tool: ① the tool should have excellent high temperature resistance and can work without cutting fluid. New cutting materials such as cemented carbide, polycrystalline ceramics and CBN are the preferred materials for dry cutting tools; ② The friction coefficient between the chip and the tool should be as small as possible (the most effective method is the tool surface coating), supplemented by the tool structure with good chip removal to reduce heat accumulation; ③ Dry cutting tools should also have higher strength and impact toughness than wet cutting tools

low temperature cold air cutting

this cutting method in April this year is a processing method that uses -10 ~ -100 ℃ cold air and a very small amount of vegetable oil to replace cooling and lubricating agent cooling. It was first proposed by Kazuhiko Yokogawa of Meiji University in Japan. It is found that in the process of metal cutting, if only a very small amount of vegetable oil with good lubrication effect and no oxidation is provided to the processing point, the processing point will lose the lubricity of the material in addition to providing comfort due to high temperature. If cold air (-10 ~ - 100 ℃) is provided to the processing point, the high temperature of the processing point can be prevented and the above situation can be avoided

the cutting performance is greatly improved during cold air cutting. The test shows that the performance of cold air cutting and grinding is more than 2 times higher than that of oil cutting and grinding. Comparison of cutting performance with and without vegetable oil cutting agent and cold air. It can be seen that only using cold air for cutting is better than storing these data in the data memory and using plants. When cold air is used together with trace vegetable oil, the cutting performance of the tool is further enhanced. Cutting conditions during the test: workpiece diameter: F92 ~ f98mm, cutting speed: 45.1 ~ 48.0m/min, feed: 0.5mm, cutting tool: tool tip radius r0.4, equivalent to skh4 high speed steel, without regrinding the blade

▲ no precision lubricating oil, no cold air processing- There is precision lubricating oil and no cold air; ● there is precision lubricating oil and cold air; ◆ there is no precision lubricating oil, there is -16.7 ℃ cold air, there is no vegetable oil cutting agent, and the cutting performance when the cold air is used. When the strong cold air with very low temperature is used for processing, in order to prevent the oil agent from freezing and losing its lubricity, a small amount of vegetable oil can be coated on the tool surface before processing, and then the strong cold air can be supplied to the processing site. That is, the effect will be better if strong cold air is not mixed with oil. The use of trace vegetable oil not only reduces the cutting energy consumption, but also eliminates the corrosion of the workpiece

second, the application of dry cutting in the field of gear processing

the new cemented carbide coating method and the use of numerical control machine tools have led to a new trend in cylindrical gear manufacturing: high-speed cutting with cemented carbide tools without cooling. If the process parameters are set optimally, the processing time can be shortened and the tool life can be longer. Mitsubishi Corporation of Japan and Gleason Corporation of the United States have carried out fruitful research in this regard

Mitsubishi Corporation of Japan launched the world's first dry roll cutting system. The cutting speed adopted by it is times of the traditional hobbing speed, which can reach 200m/min. Dry hobbing has special requirements for hobs. The special dry hob designed by Mitsubishi adopts mach7 high-speed steel, and the surface is coated with a special coating, which helps to dissipate heat and reduce tool loss. Its service life can be extended to 5 times that of the general wet cutting method. The effect of this system in processing automobile final transmission gears, large load gears, automobile pinions and planetary gears is ideal, and the production cost is reduced by at least 40%

Gleason uses carbide hobs to process bevel gears on Phoenix machine tools by dry cutting method. Compared with the traditional high-speed steel tool wet cutting method, the cutting time is reduced by 50%. Moreover, the surface roughness of gears is significantly reduced and the geometric accuracy is greatly improved. The machining accuracy can reach agma12 ~ 13 levels. With its unique design, the GP series gear hobbing machine produced by the company makes its dry cutting quality comparable to that of wet cutting. The bed is designed into a large angle slope to facilitate the flow of chips. Circulating cooling inside the bed is beneficial to maintain heat balance. In addition, the machine tool is also equipped with a set of vacuum chip removal and dust removal system. The hobbing speed of this series of hobbing machines can reach 3000r/min

the high-speed dry cutting method has the following advantages: first, it is the future of China's high molecular material industry. Because it omits the oil chip separation process, there is no cooling lubricating oil tank, oil chip separation device and corresponding electrical equipment, so the machine tool has a compact structure. Secondly, this method greatly improves the processing environment; Processing costs are also greatly reduced. In order to further extend the service life of the tool and improve the quality of the workpiece, 10 ~ 1000ml of lubricating oil can be used for micro lubrication every hour during the dry cutting of gears. The chips produced by this method can be considered as dry chips, and the accuracy, surface quality and internal stress of the workpiece are not negatively affected by trace lubricating oil. Automatic control equipment can also be used for process monitoring

LMT fette uses cemented carbide tools to dry roll cut gears, which significantly reduces the processing time and cost of a single piece of gear. Kc250h type dry gear hobbing machine developed by Japan's Keito iron works adopts carbide hobs, cold air cooling and micro lubrication for high-speed gear hobbing. Due to the supply of cold air with stable temperature, the thermal deformation of the workpiece is very small. Compared with the traditional ka220 wet hobbing machine with high-speed steel hob, the processing speed is increased by 3.2 times, and the gear accuracy is also significantly improved

III. summary

compared with wet cutting, dry cutting not only greatly improves the production efficiency of machine tools, reduces the processing cost of workpieces, but also helps to protect the environment and save natural resources. In foreign countries, the research and application of dry cutting are relatively extensive. According to the statistics of relevant departments, nearly half of enterprises in Western Europe have adopted dry cutting. Although some domestic institutions are engaged in this research work, its application in the field of gear processing is still blank

iso and jis14000 series standards were formulated and came into force in 1996 respectively. These standards have strict regulations on environmental management and monitoring. Their implementation is undoubtedly another challenge to the export of China's machine tool products. In order to improve the technical content and process innovation ability of our products and remain invincible in the international market competition, it is very necessary and urgent to carry out the research and development of dry cutting technology