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Features of large modulus hobbing
Hobbing accounts for a large share of gear processing. With the rapid development of gear processing technology, especially the requirements of high-speed and high-efficiency machining technology for large modulus and multi-teeth gears, it is urgently required to realize high-speed and high-efficiency in hobbing. To achieve high-speed hobbing, hobbing machines must improve the rigidity and drive power, to achieve numerical control, temperature compensation. The more important point is to use a high-speed, high-efficiency hob to make the cutting more rational.
At present, high-speed and high-efficiency cutting has shown many advantages and powerful vitality. It has become one of the main technical ways to increase processing efficiency and quality and reduce costs in the manufacturing industry.
Since the cutting amount of the hob corresponding to the large modulus gear is doubled, and because the number of conventional large hobs is small and the length of the teeth is long, the load distributed to each tooth is large. In the hobbing process of the hob machining gear, almost 75% of the cutting amount is achieved by the cutter tooth tip located at 1/3 of the entire tooth, and the entire tooth has only 2/3 of the entire tooth center and the root part only completes the cutting task. 25%. In fact, the load distribution and wear are very uneven in the blade tip. The wear at the tip fillet determines the tool life, with little wear on the center and root of the teeth.
Features of new structure efficient double-cut hob
The efficient and economical hob must have many slots, and the outer diameter of the hob must not be too large. The cutting face of the tooth top should be more than the cutting face of the center of the tooth and the root of the tooth root.
In order to comply with the above requirements, Hanjiang Tools Co., Ltd. has developed a hob. The new structure of an efficient double-cut hob has one row of teeth in each adjacent tooth with a complete tooth shape, and the effective part of the other tooth has only 1/1 of the tooth height. 3.
With the outer diameter of the hob, it can obtain about 20 rows of grooves, which is more than twice that of ordinary hobs.
According to the quality requirements of the workpiece, the new structure of high-efficiency double-cutting hob can be shoveled, but also can be polished. Since this type of hob has about 10 rows of complete teeth, this kind of hob can be used not only for rough cutting but also for gear finishing. In the case of roughing, the hob can also be provided with a rake angle, which reduces cutting forces and wear.
The new structure of an efficient double-cut hob can be sharpened on any standard hob sharpening bed. After the card is installed, the accuracy of the front blade surface can be guaranteed. All that is required is to adjust the depth of the grinding wheel into the reel groove. This hob design principle is not limited to involute hobs with modular or radial control, but also with special toothed hobs. According to different needs, the company can also do three-cut or four-cut hob, but the most used is a new structure of efficient double-cut hob.
The new structure of high-efficiency double-cutting hob is also applicable to the area where the gear root has high machining requirements. Since the top of the hob tooth has a large number of teeth (usually 20 teeth), in the gear machining, the root portion of the gear is processed many times, so With a new structure, an efficient double-cut hob machining gear can get a very good gear bottom arc.
Application of new structure efficient double-cut hob
The new structure of high-efficiency double-cut hob is mainly used for large module gear processing in many fields such as energy, shipbuilding, cement, mining, metallurgy, building materials and other machinery industries. In order to quickly occupy the market and expand the scale of production, many industrial companies have purchased large-scale high-speed gear hobbing machines, and the new structure of high-efficiency double-cutting hobs has such high-speed and high-efficiency cutting characteristics. The cutting efficiency of the new structure of high-efficiency double-cut hobs can be improved by 3 to 4 times compared with ordinary hobs of the same specifications. Therefore, the development of a new structure of efficient double-cutting hob to meet the needs of domestic tools, can replace the import, is China's industry gear processing requirements for high-speed and efficient cutting, but also give full play to the functions of numerical control equipment and accelerate the pace of advancement to high-end products, Has a very broad market prospects and social and economic benefits.
The new structure of efficient double-cut hob manufacturing
1 Applied Materials
The new structure of high-efficiency double-cut hob uses high-performance high-speed steel or powder metallurgy high-speed steel. Adjust the basic chemical composition of ordinary high-speed steel and add other alloying elements, so that its mechanical properties and cutting performance have significantly improved, that is, high-performance high-speed steel. High-performance high-speed steel can reach room temperature hardness HRC67 ~ 69, the corresponding increase in high temperature hardness, can be used for high-strength steel, high-temperature alloys, titanium alloys and other difficult-to-cut materials processing, and can increase tool life.
The manufacturing quality of high-speed steel is affected by many factors, among which the factors that have a large impact on performance and are difficult to improve are the uniformity of carbide distribution and the control of its grain size.
The segregation of carbides in high-speed steel smelting is severe, and the method of completely eliminating carbide segregation is powder metallurgy. The basic principle is that the molten steel melted by the high-frequency induction furnace is atomized into powder by high-pressure inert gas, and then heated and pressed into billets and then rolled or forged. Compared with smelting high-speed steel, powder metallurgy high-speed steel has many advantages such as high toughness and hardness, significant improvement in grinding performance, uniform material quality, small heat treatment distortion, etc. Its quality is stable and reliable, so the product has a longer service life. Powder metallurgy high-speed steel can cut a variety of difficult-to-machine materials, and is particularly suitable for the manufacture of various kinds of precision tools and tools with complex shapes.
2 Hob coating
The tool coating technology solves the contradiction between tool strength and toughness, and improves the toughness of the coating by optimizing the lattice structure of the coating, adding alloy elements, and multi-layer coating combinations to adapt to different cutting conditions and greatly improve the The tool's durability and cutting speed. The current research hotspot is the development of new tool coating materials with nano-multilayer structures and nano-composite coatings. Tool coatings with special properties will also become a new research field for tool coating materials.
Coating technologies mainly include chemical coating (CVD) and physical coating (PVD) technologies. The contemporary CVD coating is characterized by a multilayer coating whose coating structure includes TiCN, TiC, TiN, ZnCN and Al2O3. With good control of the CVD process, toolmakers can now provide stable quality coating tools with coating thicknesses from 5μm to 20μm, and single-layer coating thicknesses up to 0.2μm for high-hardness material workpieces. Multilayer coated alloy cutters.
PVD coating technology has a coating thickness of 2 to 5 μm on cermet and cemented carbide substrates, and such hard coatings have already been commercialized. Typical commercial coating methods include TiN, TiCN, TiAlN, CrN, TiB2, as well as multi-layer coatings such as TiN-TiAlN. The unique advantage of the PVD coating process is that it provides ultra-fine grain, smooth, low-friction and high-temperature hot cracking coatings on sharp cutting edges.
Newly developed cemented carbide tooling coatings include a combination of external TiN or TiA NPVD coatings and internal TiN/TiCN/TiNC VD coatings. The internal CVD coating provides excellent substrate adhesion and abrasion resistance, while the external PVD coating provides a strong, brittle, smooth, ultra-fine grain surface. This CVD-PVD bonded coating helps to extend the life of the tool in interrupted cutting of difficult-to-machine metal materials and steel processing.
Gear cutters are mainly coated with TiN, TiCN or TiAlN. Their chemical composition is stable, they have high red hardness and the ability to maintain high-speed cutting, reduce the dimensional error of the parts being processed, get a good surface quality, high efficiency and more Long tool life.
The new structure of high-efficiency double-cut hob is mainly used for high-speed cutting applications, usually should be PVD coating. The hob is currently mainly coated with T i N, TiCN, and TiAlN: TiN-coated hobs are suitable for machining gears with cutting fluids, cutting temperatures up to 300°C, and T i CN coating methods. Hobs are only suitable for cutting fluids, cutting temperatures up to 400°C. TiAlN coated hobs, cutting temperatures up to 800°C.
The new structure of high-efficiency double-cutting hobs can be used for large cutting speeds and larger feed rates compared to large-modular ordinary hobs of the same specifications. Usually 3 to 4 times the cutting speed of ordinary hobs. The cutting speed can refer to Table 1.
As the gear processing technology is developing in the direction of high speed, high efficiency and heavy load, the new structure efficient double-cut hob is a new hob product developed to meet this need. Due to the high number of teeth of the new structure and efficient double-cutting hob, high cutting speeds can be obtained (see Table 1), and large feed rates can be used. Compared with ordinary hobs, the new structure-efficient double-cut hob can increase efficiency 3 ~ 4 times. With the large-scale application of high-speed gear hobbing machines, with the demand of gear processing to improve efficiency and reduce costs, the new structure of high-efficiency double-cut hob will be widely used.
Hobbing accounts for a large share of gear processing. With the rapid development of gear processing technology, especially the requirements of high-speed and high-efficiency machining technology for large modulus and multi-teeth gears, it is urgently required to realize high-speed and high-efficiency in hobbing. To achieve high-speed hobbing, hobbing machines must improve the rigidity and drive power, to achieve numerical control, temperature compensation. The more important point is to use a high-speed, high-efficiency hob to make the cutting more rational.
At present, high-speed and high-efficiency cutting has shown many advantages and powerful vitality. It has become one of the main technical ways to increase processing efficiency and quality and reduce costs in the manufacturing industry.
Since the cutting amount of the hob corresponding to the large modulus gear is doubled, and because the number of conventional large hobs is small and the length of the teeth is long, the load distributed to each tooth is large. In the hobbing process of the hob machining gear, almost 75% of the cutting amount is achieved by the cutter tooth tip located at 1/3 of the entire tooth, and the entire tooth has only 2/3 of the entire tooth center and the root part only completes the cutting task. 25%. In fact, the load distribution and wear are very uneven in the blade tip. The wear at the tip fillet determines the tool life, with little wear on the center and root of the teeth.
Features of new structure efficient double-cut hob
The efficient and economical hob must have many slots, and the outer diameter of the hob must not be too large. The cutting face of the tooth top should be more than the cutting face of the center of the tooth and the root of the tooth root.
In order to comply with the above requirements, Hanjiang Tools Co., Ltd. has developed a hob. The new structure of an efficient double-cut hob has one row of teeth in each adjacent tooth with a complete tooth shape, and the effective part of the other tooth has only 1/1 of the tooth height. 3.
With the outer diameter of the hob, it can obtain about 20 rows of grooves, which is more than twice that of ordinary hobs.
According to the quality requirements of the workpiece, the new structure of high-efficiency double-cutting hob can be shoveled, but also can be polished. Since this type of hob has about 10 rows of complete teeth, this kind of hob can be used not only for rough cutting but also for gear finishing. In the case of roughing, the hob can also be provided with a rake angle, which reduces cutting forces and wear.
The new structure of an efficient double-cut hob can be sharpened on any standard hob sharpening bed. After the card is installed, the accuracy of the front blade surface can be guaranteed. All that is required is to adjust the depth of the grinding wheel into the reel groove. This hob design principle is not limited to involute hobs with modular or radial control, but also with special toothed hobs. According to different needs, the company can also do three-cut or four-cut hob, but the most used is a new structure of efficient double-cut hob.
The new structure of high-efficiency double-cutting hob is also applicable to the area where the gear root has high machining requirements. Since the top of the hob tooth has a large number of teeth (usually 20 teeth), in the gear machining, the root portion of the gear is processed many times, so With a new structure, an efficient double-cut hob machining gear can get a very good gear bottom arc.
Application of new structure efficient double-cut hob
The new structure of high-efficiency double-cut hob is mainly used for large module gear processing in many fields such as energy, shipbuilding, cement, mining, metallurgy, building materials and other machinery industries. In order to quickly occupy the market and expand the scale of production, many industrial companies have purchased large-scale high-speed gear hobbing machines, and the new structure of high-efficiency double-cutting hobs has such high-speed and high-efficiency cutting characteristics. The cutting efficiency of the new structure of high-efficiency double-cut hobs can be improved by 3 to 4 times compared with ordinary hobs of the same specifications. Therefore, the development of a new structure of efficient double-cutting hob to meet the needs of domestic tools, can replace the import, is China's industry gear processing requirements for high-speed and efficient cutting, but also give full play to the functions of numerical control equipment and accelerate the pace of advancement to high-end products, Has a very broad market prospects and social and economic benefits.
The new structure of efficient double-cut hob manufacturing
1 Applied Materials
The new structure of high-efficiency double-cut hob uses high-performance high-speed steel or powder metallurgy high-speed steel. Adjust the basic chemical composition of ordinary high-speed steel and add other alloying elements, so that its mechanical properties and cutting performance have significantly improved, that is, high-performance high-speed steel. High-performance high-speed steel can reach room temperature hardness HRC67 ~ 69, the corresponding increase in high temperature hardness, can be used for high-strength steel, high-temperature alloys, titanium alloys and other difficult-to-cut materials processing, and can increase tool life.
The manufacturing quality of high-speed steel is affected by many factors, among which the factors that have a large impact on performance and are difficult to improve are the uniformity of carbide distribution and the control of its grain size.
The segregation of carbides in high-speed steel smelting is severe, and the method of completely eliminating carbide segregation is powder metallurgy. The basic principle is that the molten steel melted by the high-frequency induction furnace is atomized into powder by high-pressure inert gas, and then heated and pressed into billets and then rolled or forged. Compared with smelting high-speed steel, powder metallurgy high-speed steel has many advantages such as high toughness and hardness, significant improvement in grinding performance, uniform material quality, small heat treatment distortion, etc. Its quality is stable and reliable, so the product has a longer service life. Powder metallurgy high-speed steel can cut a variety of difficult-to-machine materials, and is particularly suitable for the manufacture of various kinds of precision tools and tools with complex shapes.
2 Hob coating
The tool coating technology solves the contradiction between tool strength and toughness, and improves the toughness of the coating by optimizing the lattice structure of the coating, adding alloy elements, and multi-layer coating combinations to adapt to different cutting conditions and greatly improve the The tool's durability and cutting speed. The current research hotspot is the development of new tool coating materials with nano-multilayer structures and nano-composite coatings. Tool coatings with special properties will also become a new research field for tool coating materials.
Coating technologies mainly include chemical coating (CVD) and physical coating (PVD) technologies. The contemporary CVD coating is characterized by a multilayer coating whose coating structure includes TiCN, TiC, TiN, ZnCN and Al2O3. With good control of the CVD process, toolmakers can now provide stable quality coating tools with coating thicknesses from 5μm to 20μm, and single-layer coating thicknesses up to 0.2μm for high-hardness material workpieces. Multilayer coated alloy cutters.
PVD coating technology has a coating thickness of 2 to 5 μm on cermet and cemented carbide substrates, and such hard coatings have already been commercialized. Typical commercial coating methods include TiN, TiCN, TiAlN, CrN, TiB2, as well as multi-layer coatings such as TiN-TiAlN. The unique advantage of the PVD coating process is that it provides ultra-fine grain, smooth, low-friction and high-temperature hot cracking coatings on sharp cutting edges.
Newly developed cemented carbide tooling coatings include a combination of external TiN or TiA NPVD coatings and internal TiN/TiCN/TiNC VD coatings. The internal CVD coating provides excellent substrate adhesion and abrasion resistance, while the external PVD coating provides a strong, brittle, smooth, ultra-fine grain surface. This CVD-PVD bonded coating helps to extend the life of the tool in interrupted cutting of difficult-to-machine metal materials and steel processing.
Gear cutters are mainly coated with TiN, TiCN or TiAlN. Their chemical composition is stable, they have high red hardness and the ability to maintain high-speed cutting, reduce the dimensional error of the parts being processed, get a good surface quality, high efficiency and more Long tool life.
The new structure of high-efficiency double-cut hob is mainly used for high-speed cutting applications, usually should be PVD coating. The hob is currently mainly coated with T i N, TiCN, and TiAlN: TiN-coated hobs are suitable for machining gears with cutting fluids, cutting temperatures up to 300°C, and T i CN coating methods. Hobs are only suitable for cutting fluids, cutting temperatures up to 400°C. TiAlN coated hobs, cutting temperatures up to 800°C.
The new structure of high-efficiency double-cutting hobs can be used for large cutting speeds and larger feed rates compared to large-modular ordinary hobs of the same specifications. Usually 3 to 4 times the cutting speed of ordinary hobs. The cutting speed can refer to Table 1.
As the gear processing technology is developing in the direction of high speed, high efficiency and heavy load, the new structure efficient double-cut hob is a new hob product developed to meet this need. Due to the high number of teeth of the new structure and efficient double-cutting hob, high cutting speeds can be obtained (see Table 1), and large feed rates can be used. Compared with ordinary hobs, the new structure-efficient double-cut hob can increase efficiency 3 ~ 4 times. With the large-scale application of high-speed gear hobbing machines, with the demand of gear processing to improve efficiency and reduce costs, the new structure of high-efficiency double-cut hob will be widely used.
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