Research on the Technology of Spiral Bevel Gears of Scraper, Li Liqin (Taiyuan Mine (Group) Co., Ltd., Taiyuan 030009, Shanxi) The quality problem of gear pair meshing; satisfactory results obtained through specific tests, simple process and short production cycle , low cost, and applied in production.
1The traditional process of the spiral bevel gear of the scraper and its existing problems The unstable processing quality of the spiral bevel gear is a difficult problem in the mechanical manufacturing, especially the engineering machinery used by the factory for the scraper and other underground mining equipment. Spiral bevel gears have a large transmission ratio and require higher wear resistance, fatigue strength, core hardness and impact toughness than machine tool gears. The design requires that the material is 20CrMnTi and is subjected to carburizing (or carbonitriding) quenching. The process requires heat treatment and shot peening (cold hardening) on ​​the gear surface to eliminate the tensile stress in the dangerous zone and form a considerable compression. The stress, in order to increase the strength of the gear, but because of the large deformation of the gear in the heat treatment, the manufacturing precision of the gear is difficult to guarantee, and even the heat treatment deformation of the scrapped gear including the tooth deformation and the wheel blank deformation is severely caused. Generally, the spiral bevel gear tends to reduce its helix angle and flank clearance after heat treatment, and the pressure angle also changes, which will cause changes in the contact area of ​​the tooth surface and increase the running noise of the gear.
In order to overcome the large deformation of such gears in heat treatment and improve the manufacturing precision of the gears, it is generally controlled by trial and error in China. That is to repeat the cutting tooth adjustment and heat treatment deformation test to find the heat treatment deformation law to determine the technical requirements of the cutting teeth before heat treatment, namely: 1 first cut the gear according to the cutting tooth calculation data, and cut the good gear as a standard The pinion gear is cut, the position of the contact zone is preliminarily selected according to the change rule of the same material after heat treatment, and the tooth side clearance is also properly enlarged 2 for measurement recording. After the comparison, the initial situation of gear deformation after heat treatment can be obtained, if the heat treatment fails For technical requirements, the incisor adjustment and heat treatment deformation test should be repeated until the requirements are met.
According to this method, it is more labor-intensive and time-consuming to improve the manufacturing precision of spiral bevel gears. In the mass production of spiral bevel gears, specialized manufacturers, for a relatively simple product, spend a certain amount of energy to explore, in order to continuously improve the spiral bevel gear Manufacturing quality is worthwhile, but for manufacturers of multi-variety and small-volume production, on the one hand, the manufacturing cost is increased, on the other hand, the manufacturing time is long and the market demand cannot be met.
In particular, the delivery time of the parts is very short, and it is necessary to shorten the manufacturing time of the products.
In recent years, the processing technology of grinding and hard tooth surface scraping has been developed, but the general manufacturers do not have the equipment and conditions in this respect, and the manufacturing cost of the product is also high. There are certain difficulties, not to mention that there are still many technical problems to be further studied and resolved.
2 new technology of spiral bevel gears. There are many kinds of spiral bevel gears produced by our factory. After summarizing the advantages and disadvantages of the above various methods, after a long time of exploration and practice, we found that it is used in heavy machinery such as scrapers and mining. Spiral bevel gears on engineering machinery such as coal mining machines and other underground mining equipment, the deformation after heat treatment mainly occurs on the large gears, and the corresponding deformation of the small gears is small. These gears are gears with relatively large transmissions, and the high displacement and tangential displacement of the helical bevel gears are determined according to the transmission ratio. The larger the transmission ratio, the higher displacement coefficient and the tangential displacement of the gear teeth. The larger the coefficient, the more the teeth of the pinion are strengthened, and the smaller the deformation of the pinion teeth after heat treatment. This is because the 1 high displacement avoids the undercut of the pinion, and the undercut is most likely to cause the tooth deformation in the tooth height direction after heat treatment; 2 the positive height displacement makes the person, the deputy section chief of the technical department, the engineer, the Shanxi Mining Institute in 1989 Graduation, undergraduate.
The tooth root of the pinion becomes thicker, and the root root becomes thicker, which not only reduces the thermal deformation of the gear teeth, but also increases the bending strength of the gear; 3 positive displacement causes the radius of curvature of the pinion tooth shape to increase, and the thermal deformation is reduced. It also reduces the contact stress when the teeth are meshed, thereby improving the fatigue strength of the gear teeth; 4 using the tangential tangential correction to increase the tooth thickness of the pinion, so that the teeth of the pinion become more robust It can effectively prevent the thermal deformation of the teeth. The large gear teeth are correspondingly thin, and the deformation of the large gear teeth is large after heat treatment. In addition, when the transmission is relatively large, the shape of the large gear is mostly a thin annular structure. Therefore, the wheel blank of the large gear According to the above analysis, the new process of matching the large gears of the pinion gear and the heat-treated finished product in the process effectively overcomes the problem that the gear meshing quality is seriously degraded due to thermal deformation, and A satisfactory result has been obtained. The spiral bevel gear manufactured by this method has low cost, short production cycle and simple and easy process. The specific procedures are as follows: (1) Calculate the data according to the cutting teeth, cut the large gears, and then perform the carburizing (or carbonitriding) quenching after the large gears are processed. When quenching, the quenching die is used to control the deformation of the large gears as much as possible; After carburizing (or carbonitriding) quenching, the finished product is geared with a large gear to cut the pinion, while cutting and rolling on the rolling inspection machine, adjusting the contact area until the contact area is satisfied, regardless of the gear teeth of the large gear What kind of deformation occurs after heat treatment, because the gear teeth of the pinion are always matched with the heat-deformed finished large gear, which always ensures the meshing of the pinion and the large gear, which fundamentally eliminates the large heat treatment. The problem of the quality of the deformed large gear and the small-sized pinion mesh is reduced, thereby ensuring that the user can adjust the contact area of ​​the spiral bevel gear smoothly during assembly. This method is most suitable for the transmission and is relatively large. A spiral bevel gear pair made of carbon steel and having a large deformation after heat treatment. For example, the spiral bevel gear pair produced by our factory, the large end face modulus 9 small gear teeth Z1=14 large gear teeth Z2=46 midpoint spiral angle 35°, tooth angle T= 20 material 20Ci.MnTi, carburizing and quenching, The process route is as follows: large gear (passive spiral gear): forging - annealing - rough car - normal fire car + coarse iron tooth fine iron tooth other fine machining - carburizing - quenching - tempering - shot peening - other fine Machining - Rolling option (with pinion) and engraved pairing number paired oil seal package pinion (shaft spiral bevel gear): forging - annealing - rough car - normalizing - finishing car - coarse iron tooth - fine iron tooth ( When the fine iron is matched with the large gear of the finished product after heat treatment, and fine-milling, while rolling the contact area on the rolling inspection machine until the contact area and the tooth back gap are satisfactory) Other fine machining - carburizing - quenching - back Fire - shot peening - other precision machine processing pairing number - paired oil seal packaging 3 Conclusion We have explored the processing method of spiral bevel gear in the long-term production practice to ensure the spiral bevel gear meshing quality, and low cost Short production cycle, very suitable
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