At present, the tooth forming process of each company in the gear manufacturing industry is roughly the same. Most of the automobile gears adopt the hobbing and hot post-crushing process. A few enterprises and some car companies adopt the hobbing and hot post-grinding process, while the heavy-duty gear transmission industry generally adopts the hot-rolling grinding process. Hobbing accounts for more than 70% of the gear making process, and high-speed hobbing is of great significance. In order to achieve high-speed hobbing, the hobbing machine must increase the rigidity, improve the driving power of the hobbing head, improve the numerical control, servo function, achieve temperature compensation, etc., and also promote the application of high-performance, high-efficiency tools.
The hob materials currently used in production are mainly high-speed steel, and there are also carbide insert hobs or integral powder metallurgy carbide hobs.
High-speed steel hobs are mostly coated, such as commonly used tool materials such as M35, M42, A4, TiN coating, good matrix toughness, heat-resistant and wear-resistant coating, preventing chipping, and cutting speed can be increased to 120. ~150m/min. The solid carbide hob manufactured by the powder metallurgy sintering forming method also has a good effect. The tool is coated and the cutting speed can be increased to more than 250m / min, and the axial feed can reach 3 ~ 6mm / r. And as long as the equipment conditions allow, dry cut can be achieved. The use of dry cutting can reduce the environmental pollution caused by the oil mist caused by the cutting coolant, and the excellent performance of the carbide coated tool greatly prolongs the service life and reduces the processing cost.
When the hobbing, the hob and the workpiece are equivalent to a pair of intermeshing worm worm gears. According to the continuous development method, the linear toothed blade of the hob envelops the involute tooth shape of the workpiece. The hobbing process requires a suitable machining allowance for subsequent machining, such as shaving after heat treatment or grinding after heat treatment, and the root portion is machined to the workpiece in the hobbing. The higher the hob speed, the more the number of heads, the shorter the cutting time. In order to improve efficiency, in addition to increasing the hob speed and feed rate, multi-head hobs should be used whenever possible. Increasing the number of heads can significantly increase the cutting speed and reduce the number of cutting edges, which is beneficial to the cutting of the hob, reducing wear and improving tool life. Hobs are generally used in 2 to 4 heads, and there are also 5 to 7 heads.
Increasing the diameter of the hob and the number of sipe increases the chip thickness and increases productivity. However, since the diameter of the hob is limited by the structure of the machine tool, the room for increase is not large. Increasing the number of sipe affects the strength of the cutter teeth in many cases, so that a pair of two rows and three rows of cogging grooves are combined. Tooth hob or three-tooth hob. This hob can be used for both rough and fine cuts. In particular, the increase in the tooth strength can increase the amount of cutting, improve the chip formation conditions, and can properly accommodate the cutting area along the entire cutting edge to meet the requirements of heavy cutting. Compared with ordinary hobs, the efficiency is increased by 4 to 6 times, so it is often called heavy cutting hob.
During the whole hobbing process, while the hob is fed along the axial direction of the workpiece, it is also displaced along the axial direction of the hob, that is, the boring motion, so that all the teeth on the hob are involved in the cutting, and the wear of the teeth is balanced. Improve tool durability. If it is found that the tooth surface roughness of the workpiece is obviously deteriorated, there are spots, burrs, or abnormal sound, it should be sharpened in time.
The method of machining hardened gears with carbide hobs has been used in many years in the enterprise, but in most cases it is only used to replace rough grinding. This is because when the hard tooth surface is rolled, the hob of the hob is cut and cut to cause a sudden change in the tooth shape of the workpiece. In addition, the instantaneous high temperature of the workpiece causes the tooth surface of the workpiece to anneal to form a soft point, which affects the contact strength of the workpiece. The metal removal rate is higher than the grinding tooth, which has a better effect instead of the coarse grinding. An example of successful machining of a helical bevel gear with a cemented carbide framed cutter disc is also available, but the forming tool is very expensive, has a limited life, and is not widely used.
For internal, double or multiple gears, the gear shaping process is often applied. Compared with the hobbing, although both work according to the principle of development, the impact of the cutting and cutting of the tool during the gear insertion and the up and down movement of the tool spindle are affected by the inertia force, unless the hobbing is not allowed under the process conditions. It is not possible to apply the gear shaping process. Because of this, the research progress of the dry cutting and inserting method is not much progress.
On the modern large-scale hobbing machine, the internal gear milling head can be configured according to the user's requirements. The disc-shaped milling cutter is used to insert and insert, and the internal gear ring tooth machining allowance is cut by the tooth-by-tooth division, and then the internal tooth grinding is used. The cutting method obtains the final tooth shape. The efficiency is increased several times compared to the use of the gear shaping process. Of course, the inner diameter of the workpiece is large enough due to the limitation of the internal tooth milling head. In addition, when the inner spur is milled by the milling inserting method, the cutting edge of the finishing cutter can be made into the same involute shape of the workpiece, and the margin reserved for the grinding tooth after machining can be smaller; the milling helical tooth However, although the seat can be moved at an angle according to the helix angle, the disc cutter cannot be continuously developed like the hobbing, so the cut tooth shape is approximately involute, leaving the remaining amount of grinding teeth Slightly larger. The high-power internal gear milling head is driven by a preloaded mechanical drive chain, driven by a motor or hydraulic motor, providing basic conditions for efficient machining. Coated milling cutters or carbide insert milling cutters with optimized cutting parameters provide a guarantee for improved metal removal rates and extended tool life, as well as dry cutting. For example, in the P1600/2000 high-efficiency gear hobbing machine with internal tooth milling head, it processes 107 teeth, 9-modulus, 8 degree helix angle, 210 mm tooth width, internal gear of 42CrMoS4 material, air-cooled dry cutting, total milling time For 135 minutes (one-time cutting), and the same amount of removal, using the tooth-tooth method on the ordinary machine tool, at least two or three days!
Users are increasingly demanding to reduce gear noise, and the traditional roll-to-roll enthalpy process cannot meet this requirement due to limited capabilities. If the hot-rolling process is used, the decision-makers of the enterprise will be uncertain due to the high manufacturing cost. For mass-produced vehicle transmission gears, the powerful internal tooth honing wheel boring process solves this contradictory vehicle network well and provides a feasible method for gear finishing. The traditional honing process has a maximum honing allowance of no more than 10 microns. It is only after the shaving of the heat-treated tooth surface to improve the surface quality and thus the tooth profile. The strong internal gingival is different. After the heat treatment, the larger machining allowance (20-50 microns) can be finished to meet the process requirements. Moreover, the mesh texture can be formed on the tooth surface, unlike when grinding the teeth. The periodic strip texture reduces the tooth meshing frequency and thus reduces noise. The honing tool can be made of resin bonded sand or corundum or CBN honing wheel. In order to save costs when machining external teeth, a resin-bonded honing wheel that can be trimmed is usually used, and the dressing wheel is used for dressing during dressing. The strong tooth decay process is mainly used in mass-produced automotive gears. The workpiece modulus is 0.3 to 6 mm, the diameter is 10 to 250 mm, the tooth width is 20 to 50 mm, and the final gear accuracy can reach 6 or higher. The processing cost is about For grinding half of the tooth.
The hob materials currently used in production are mainly high-speed steel, and there are also carbide insert hobs or integral powder metallurgy carbide hobs.
High-speed steel hobs are mostly coated, such as commonly used tool materials such as M35, M42, A4, TiN coating, good matrix toughness, heat-resistant and wear-resistant coating, preventing chipping, and cutting speed can be increased to 120. ~150m/min. The solid carbide hob manufactured by the powder metallurgy sintering forming method also has a good effect. The tool is coated and the cutting speed can be increased to more than 250m / min, and the axial feed can reach 3 ~ 6mm / r. And as long as the equipment conditions allow, dry cut can be achieved. The use of dry cutting can reduce the environmental pollution caused by the oil mist caused by the cutting coolant, and the excellent performance of the carbide coated tool greatly prolongs the service life and reduces the processing cost.
When the hobbing, the hob and the workpiece are equivalent to a pair of intermeshing worm worm gears. According to the continuous development method, the linear toothed blade of the hob envelops the involute tooth shape of the workpiece. The hobbing process requires a suitable machining allowance for subsequent machining, such as shaving after heat treatment or grinding after heat treatment, and the root portion is machined to the workpiece in the hobbing. The higher the hob speed, the more the number of heads, the shorter the cutting time. In order to improve efficiency, in addition to increasing the hob speed and feed rate, multi-head hobs should be used whenever possible. Increasing the number of heads can significantly increase the cutting speed and reduce the number of cutting edges, which is beneficial to the cutting of the hob, reducing wear and improving tool life. Hobs are generally used in 2 to 4 heads, and there are also 5 to 7 heads.
Increasing the diameter of the hob and the number of sipe increases the chip thickness and increases productivity. However, since the diameter of the hob is limited by the structure of the machine tool, the room for increase is not large. Increasing the number of sipe affects the strength of the cutter teeth in many cases, so that a pair of two rows and three rows of cogging grooves are combined. Tooth hob or three-tooth hob. This hob can be used for both rough and fine cuts. In particular, the increase in the tooth strength can increase the amount of cutting, improve the chip formation conditions, and can properly accommodate the cutting area along the entire cutting edge to meet the requirements of heavy cutting. Compared with ordinary hobs, the efficiency is increased by 4 to 6 times, so it is often called heavy cutting hob.
During the whole hobbing process, while the hob is fed along the axial direction of the workpiece, it is also displaced along the axial direction of the hob, that is, the boring motion, so that all the teeth on the hob are involved in the cutting, and the wear of the teeth is balanced. Improve tool durability. If it is found that the tooth surface roughness of the workpiece is obviously deteriorated, there are spots, burrs, or abnormal sound, it should be sharpened in time.
The method of machining hardened gears with carbide hobs has been used in many years in the enterprise, but in most cases it is only used to replace rough grinding. This is because when the hard tooth surface is rolled, the hob of the hob is cut and cut to cause a sudden change in the tooth shape of the workpiece. In addition, the instantaneous high temperature of the workpiece causes the tooth surface of the workpiece to anneal to form a soft point, which affects the contact strength of the workpiece. The metal removal rate is higher than the grinding tooth, which has a better effect instead of the coarse grinding. An example of successful machining of a helical bevel gear with a cemented carbide framed cutter disc is also available, but the forming tool is very expensive, has a limited life, and is not widely used.
For internal, double or multiple gears, the gear shaping process is often applied. Compared with the hobbing, although both work according to the principle of development, the impact of the cutting and cutting of the tool during the gear insertion and the up and down movement of the tool spindle are affected by the inertia force, unless the hobbing is not allowed under the process conditions. It is not possible to apply the gear shaping process. Because of this, the research progress of the dry cutting and inserting method is not much progress.
On the modern large-scale hobbing machine, the internal gear milling head can be configured according to the user's requirements. The disc-shaped milling cutter is used to insert and insert, and the internal gear ring tooth machining allowance is cut by the tooth-by-tooth division, and then the internal tooth grinding is used. The cutting method obtains the final tooth shape. The efficiency is increased several times compared to the use of the gear shaping process. Of course, the inner diameter of the workpiece is large enough due to the limitation of the internal tooth milling head. In addition, when the inner spur is milled by the milling inserting method, the cutting edge of the finishing cutter can be made into the same involute shape of the workpiece, and the margin reserved for the grinding tooth after machining can be smaller; the milling helical tooth However, although the seat can be moved at an angle according to the helix angle, the disc cutter cannot be continuously developed like the hobbing, so the cut tooth shape is approximately involute, leaving the remaining amount of grinding teeth Slightly larger. The high-power internal gear milling head is driven by a preloaded mechanical drive chain, driven by a motor or hydraulic motor, providing basic conditions for efficient machining. Coated milling cutters or carbide insert milling cutters with optimized cutting parameters provide a guarantee for improved metal removal rates and extended tool life, as well as dry cutting. For example, in the P1600/2000 high-efficiency gear hobbing machine with internal tooth milling head, it processes 107 teeth, 9-modulus, 8 degree helix angle, 210 mm tooth width, internal gear of 42CrMoS4 material, air-cooled dry cutting, total milling time For 135 minutes (one-time cutting), and the same amount of removal, using the tooth-tooth method on the ordinary machine tool, at least two or three days!
Users are increasingly demanding to reduce gear noise, and the traditional roll-to-roll enthalpy process cannot meet this requirement due to limited capabilities. If the hot-rolling process is used, the decision-makers of the enterprise will be uncertain due to the high manufacturing cost. For mass-produced vehicle transmission gears, the powerful internal tooth honing wheel boring process solves this contradictory vehicle network well and provides a feasible method for gear finishing. The traditional honing process has a maximum honing allowance of no more than 10 microns. It is only after the shaving of the heat-treated tooth surface to improve the surface quality and thus the tooth profile. The strong internal gingival is different. After the heat treatment, the larger machining allowance (20-50 microns) can be finished to meet the process requirements. Moreover, the mesh texture can be formed on the tooth surface, unlike when grinding the teeth. The periodic strip texture reduces the tooth meshing frequency and thus reduces noise. The honing tool can be made of resin bonded sand or corundum or CBN honing wheel. In order to save costs when machining external teeth, a resin-bonded honing wheel that can be trimmed is usually used, and the dressing wheel is used for dressing during dressing. The strong tooth decay process is mainly used in mass-produced automotive gears. The workpiece modulus is 0.3 to 6 mm, the diameter is 10 to 250 mm, the tooth width is 20 to 50 mm, and the final gear accuracy can reach 6 or higher. The processing cost is about For grinding half of the tooth.
Stainless Steel Welded Round Tube
Stainless Steel Welded Round Tube,Stainless Steel Sanitary Tube,Stainless Steel Sanitary Pipe,Stainless Steel Bowl With Lid
Foshan Maysky Stainless Steel Co., Limited , https://www.mayskysteel.com