As a kind of transmission machinery with compact structure, large transmission ratio and self-locking function under specific conditions, the worm gear and worm reducer belongs to the list of commonly used reducers. Among them, the hollow shaft worm gear reducer not only has the above-mentioned characteristics, but also has the advantages of convenient installation and reasonable structure, so it is used more and more widely. The hollow shaft worm gear reducer adds a helical gear reducer at the input end of the worm gear and worm reducer. The multi-stage reducer composed of it can obtain extremely low output speed, which is a combination of helical gear stage and worm gear stage. Compared with the pure single-stage worm gear reducer, it has higher efficiency, less vibration, lower noise and lower energy consumption.
Common problems and their causes are as follows: First, the reducer gets hot and leaks oil; second, the worm wheel is worn; third, the small helical gear in transmission is worn; fourth, the bearing (at the worm) is damaged.
Regarding the heating and oil leakage of the reducer, since the worm gear reducer usually uses non-ferrous metals to make the worm wheel to improve efficiency, and the worm is made of harder steel, which belongs to sliding friction transmission, relatively high heat will be generated during the operation, resulting in differences between the various parts of the reducer and the seal due to thermal expansion, and then gaps are formed on the various mating surfaces, and the oil becomes thinner due to the increase in temperature, which is prone to causing leakage. The main reasons include four points: First, whether the material matching is reasonable; second, the surface quality of the meshing friction surface; third, whether the selection and addition amount of the lubricating oil are correct; fourth, the assembly quality and the use environment.
In terms of worm wheel wear, the worm wheel generally uses tin bronze, and the paired worm material usually uses 45 steel quenched to HRC45 to 55, and 40C quenched to HRC50 to 55 is also often used, and it is ground to a roughness of RaO.8fcm by a worm grinding machine. When the reducer operates normally, the worm is like a hardened “file” that continuously files the worm wheel, resulting in wear of the worm wheel. Generally speaking, this kind of wear is relatively slow, and some reducers in a certain factory can be used for more than ten years. If the wear rate is relatively fast, it is necessary to consider whether the selection of the reducer is correct, whether there is overload operation, the material of the worm and worm wheel, assembly quality or use environment and other reasons.
The wear of the small helical gear in transmission usually occurs on the reducer installed vertically, which is mainly related to the amount and choice of lubricating oil added. When installed vertically, it is very easy to cause insufficient lubricating oil. When the reducer stops operating, the transmission gear oil between the motor and the reducer flows away, and the gears cannot get the due lubrication protection. Due to the lack of effective lubrication during starting or operating, mechanical wear and even damage are caused.
When the worm bearing is damaged, even if the reducer is sealed well, it is still often found in the factory that the gear oil in the reducer has been emulsified, and the bearings have rusted, corroded and damaged. This is due to the condensation of moisture generated after the gear oil changes from hot to cold during the operation and stop process of the reducer, and of course it is also closely related to the quality of the bearings and the assembly process method.
The solutions are as follows:
First of all, it is necessary to ensure the assembly quality. To achieve this goal, the factory has purchased and fabricated some special tools. When disassembling and installing the worm wheel, worm, bearing, gear and other components of the reducer, try to avoid directly hitting with other tools such as hammers; when replacing gears, worm wheels and worms, choose original factory parts and replace them in pairs as much as possible; when assembling the output shaft, pay attention to the tolerance fit. When D≤50mm, use H7/k6, and when D＞50mm, use H7/m6. At the same time, anti-sticking agent or red lead oil should be used to protect the hollow shaft, prevent wear, rust and fouling of the mating area, and facilitate disassembly during maintenance.
Secondly, do a good job in the selection of lubricating oil and additives. Worm gear reducers generally use 220# gear oil. For some reducers with heavy loads, frequent starts, and poor use environments, the factory also uses some lubricating oil additives (such as Kejiajia of Anzhi Chemical Company), so that when the reducer stops operating, the gear oil still adheres to the gear surface to form a protective film to prevent metal-to-metal contact during heavy load, low speed, high torque and start-up. The additives also include seal regulator and anti-leakage agent, which can keep the seal soft and elastic and effectively reduce the phenomenon of lubricating oil leakage.
Furthermore, reasonably select the installation position of the reducer. When the position permits, try to avoid vertical installation as much as possible. When installed vertically, the amount of lubricating oil added is much more than that of horizontal installation, which is prone to causing the reducer to heat up and leak oil. In the 40,000 bottles/hour pure draft beer production line introduced by the factory, some are installed vertically. After running for a period of time, the transmission pinion has relatively large wear or even damage. After adjustment, the situation has been significantly improved.
Finally, establish the corresponding lubrication maintenance system. The factory maintains the reducer according to the “five fixed” principles of lubrication work, so that each reducer has a person responsible for regular inspection. When it is found in the work that the oil temperature rises significantly, the temperature rise exceeds 40°C or the oil temperature exceeds 80°C, the quality of the oil decreases or a large amount of copper powder is found in the oil and abnormal noise and other phenomena occur, it is necessary to immediately stop using and timely overhaul, troubleshoot, and use it again after replacing the lubricating oil. When refueling, pay attention to the consistency of the oil amount and the installation position to ensure that the reducer is properly lubricated.
In short, the hollow shaft type worm reducer is convenient to install, has a reasonable structure, and is reliable and durable. Of course, it is also necessary to pay attention to the selection of the model of the reducer. Strong companies will, according to the design key points such as the shape of the reducer, the layout of the cooling ribs, the calculation of the heat balance, and the design of the oil circuit, combined with the actual use and operating conditions of the reducer, adopt excellent manufacturing techniques to produce reducers with high quality, reliability and durability. As long as users use and maintain it correctly, they can obtain satisfactory results.
