With the development of numerical control technology, the machine tool has been greatly promoted to the rapid development of numerical control, high speed, high efficiency and compound direction. In order to meet the needs of high precision and high efficiency machining, in recent years, the development of gear tools at home and abroad is also related to CNC high efficiency machine tools. The development has been synchronized and made great progress. These advances mainly depend on several aspects: more advanced design techniques, more advanced CNC special processing technology and precision inspection technology, superior tool materials, advanced surface coatings. Technology, and heat treatment technology for high speed steel gear cutters is also key.
In recent years, the development trend and characteristics of gear cutters are mainly reflected in the following aspects:
Environmentally friendly dry cutting
Environmentally friendly dry cutting has been applied in gear processing. Domestic and foreign OEMs such as Gleason, Mitsubishi, and Chongqing, China have developed special dry-cut hobbing machines. Compared with the traditional wet cutting method, the dry cutting method does not require a coolant, which is environmentally friendly and reduces the cost of hobbing processing. The dry cutting method can also adopt a higher cutting speed and improve the processing efficiency. According to the processing requirements of dry-cutting machine tools, all major tool manufacturers have developed environmentally-friendly dry-cut hobs, such as Gleason, NACHI, SU, and Han tools. Environmentally-friendly dry-cut hobs are made of solid carbide hobs. , carbide indexable hob, powder metallurgy high speed steel hob. The solid carbide hob is generally used for gears with a modulus less than 2mm, the precision can reach AAA, the cutting speed can reach more than 250m/min, and the carbide indexable hob is generally used for gears with a modulus greater than 6~45mm. It is mainly used for rough cutting before grinding. The cutting speed can reach 120~150m/min. The powder metallurgy high-speed steel hob generally has a wider range of modulus, and can cover all the modulus segments. These tools are all made of high-performance powder metallurgy. High-speed steel manufacturing, good tool toughness, small processing difficulty, its structural features are small diameter and long structure, reducing the time of cutting and cutting, and the series of knives, improving tool durability and processing efficiency, using powder metallurgy materials and high-performance coating The cutting speed can reach 150~200m/min, and the precision is DINAA or GBAA. Environmentally friendly dry cutting will become the main way of cutting teeth.
Gear cutter hard alloying
In the traditional sense, gear cutter materials are generally high-speed steel (high-performance powder metallurgy high-speed steel has also been widely used). With the development of cemented carbide materials and advances in processing technology, the proportion of cemented carbide tools is getting higher and higher. In developed countries in Europe, it has reached more than 70%. In recent years, various tool manufacturers such as Gleason, Kennametal, Fette, Ingersoll and Sandvik coromant have developed various carbide indexable gear cutters, which greatly improved the efficiency of gear processing. Increased tool life! Indexable carbide gear hobs with 1 or 2 heads, inserts can be indexed 2 or 4 times, modulus range M5.5~M40, compared to high speed steel hobs Higher up to 100~150m/min (the cutting speed of similar high-speed steel insert hob is only 30m/min), dry cutting, cutting efficiency is increased by 1~3 times, except for large modulus indexable alloy hob, Sandvik Coromant has also developed a machine-clamped carbide hob in the range of M5~M8. The difference is that the hob uses one blade for each tooth, and the assembly precision is up to DIN B, and the structure is novel. In the field of small modulus (M<2) gear processing, a series of solid carbide hobs have been developed with an accuracy of AAA-A and a cutting speed of over 250m/min. At the same time, the above companies have developed hard Alloy indexable gear milling cutter can be used for both external gear processing and high-efficiency machining of internal gears, especially for the high-efficiency machining of large internal ring gears in the wind power industry. In addition to rough cutting, it can also directly cut gears. It can be stabilized to GB8 grade, which also shows the advancement of cemented carbide insert manufacturing technology. The module range is M6~M40, the cutting speed can reach 100~150m/min, and the cutting efficiency is increased by 1~3 times. It is worth mentioning that at home and abroad, CBN, PCD and other super-hard tools have also been used more and more, and will become the direction of future tool development.
Tool size is oversized
With the large-scale processing machine tools, the demand for large gears for major equipment has increased, and a variety of super-large tools have appeared. In recent years, the 40- to 50-hour arc milling cutters developed in the past are matched with large-scale arc gear machines for processing over 1600~2000mm. Spiral bevel gears, super large spiral bevel gears are mainly used in ships, metallurgy, petroleum machinery and other industries; M40～M45 super large modulus hobs are used to process large cylindrical gears with large hobbing machines, which are widely used in cement, metallurgy, lifting, shipbuilding and other industries. Application; For the processing of large internal gears, in addition to the special internal milling cutter, the special gear shaping tool has been developed from the previous modulus 18 to the current M25. The development of various oversized tools also shows the improvement of the innovation ability of the tool enterprise.
Development of coating technology and close integration of tools
In the development of modern tools, the application of coating technology plays a key role. It can be said that advanced coating technology has made modern high-efficiency cutting tools. At present, both chemical coating (CVD) and physical coating (PVD) are actively developing new coating materials; from single coating to multilayer coating, gradient coating, nano coating, nano composite coating The layer is oriented in the same direction; at the same time, the coating technology pays more attention to the combination of the pre-coating process and the post-coating process; the advanced coating technology has higher red hardness (microhardness up to 3300Hv and above), heat resistance And oxidation resistance (use temperature up to 1100 ° C); better toughness, bonding and lower friction coefficient; coating technology contribution to the tool is: significantly improve the wear resistance and use of the tool The life span has realized the high-speed and high-efficiency and dry cutting of the tool, and realized the cutting of high-hard materials and various difficult-to-machine materials, which greatly promoted the development of the machinery manufacturing industry. This promotion and impact will become more and more obvious!
With the rapid development of gear machining in the direction of numerical control, high efficiency, high precision and compound flexibility, the development of cutting tools has also developed rapidly in the direction of environmental protection, high speed and high efficiency, super large and super hard. These developments keep pace with the development of machine tools. The development benefits from the more advanced design technology of the tool, the more advanced CNC machining technology, the advanced materials with superior performance, and the more advanced coating technology. However, the overall level of domestic high-end gear cutters still has a big gap with foreign countries. Our domestic tool counterparts should catch up!
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