Worm gear reducers are a type of transmission machinery characterized by their compact structure, large transmission ratio, and self-locking function under certain conditions. They are among the most commonly used reducers. Hollow shaft worm gear reducers not only possess these characteristics but also offer convenient installation and a rational structure, leading to their increasingly widespread application. By adding a helical gear reducer to the input end of a worm gear reducer, a multi-stage reducer can achieve very low output speeds. This combination of helical and worm gear stages results in higher efficiency than a pure single-stage worm gear reducer. Furthermore, it exhibits low vibration, low noise, and low energy consumption.
Common problems and their causes. (1) Gearbox overheating and oil leakage, (2) Worm gear wear, (3) Wear of transmission small helical gear, (4) Bearing (worm) damage.
1. Gearbox overheating and oil leakage. To improve efficiency, worm gear reducers generally use non-ferrous metals for the worm wheel and harder steel for the worm. Because it's a sliding friction transmission, it generates significant heat during operation. This causes thermal expansion differences between the reducer's parts and seals, creating gaps at the mating surfaces. The oil thins due to the increased temperature, making leakage more likely. There are four main reasons for this: first, the appropriateness of the material combination; second, the surface quality of the meshing friction surfaces; third, the selection and correct dosage of the lubricating oil; and fourth, the assembly quality and the operating environment.
2. Worm Gear Wear. Worm gears are generally made of tin bronze, while the mating worm is typically made of 45 steel hardened to HRC45-55, or often 40C hardened to HRC50-55. The material is then ground to a surface roughness of Ra 0.8 cm using a worm grinder. During normal operation of the reducer, the worm acts like a hardened "file," constantly grinding against the worm gear, causing wear. Generally, this wear is slow; some reducers from certain manufacturers can last for over 10 years. If the wear rate is rapid, it's necessary to consider whether the reducer selection is correct, whether it's being overloaded, the material of the worm gear, assembly quality, or the operating environment.
3. Wear of the small helical gear in the transmission. This generally occurs in vertically mounted reducers and is mainly related to the amount of lubricating oil added and the choice of lubricating oil. When vertically mounted, it is easy to cause insufficient lubricating oil. When the reducer stops running, the transmission gear oil between the motor and the reducer leaks out, and the gears do not receive the necessary lubrication protection. Ineffective lubrication during startup or operation leads to mechanical wear or even damage.
4. Worm bearing damage. When the reducer malfunctions, even if the gearbox is well-sealed, the factory often finds that the gear oil inside the reducer has been emulsified, and the bearings have rusted, corroded, and damaged. This is because the moisture generated when the gear oil cools down during operation and shutdown causes condensation; of course, it is also closely related to the quality of the bearings and the assembly process.
Solution:
(1) Ensure assembly quality. To ensure assembly quality, the factory purchased and manufactured some special tools. When disassembling and installing components such as worm gears, worm shafts, bearings, and gears of the reducer, direct hammering with other tools should be avoided as much as possible. When replacing gears, worm gears, and worm shafts, original factory parts should be used as much as possible and they should be replaced in pairs. When assembling the output shaft, attention should be paid to tolerance matching. For D≤50mm, H7/k6 should be used, and for D>50mm, H7/m6 should be used. At the same time, anti-sticking agent or red lead oil should be used to protect the hollow shaft, prevent wear and rust, and prevent scale buildup on the mating surface, which would make disassembly difficult during maintenance.
(2) Selection of Lubricating Oil and Additives. Worm gear reducers generally use 220# gear oil. For reducers with heavy loads, frequent starts, and harsh operating environments, the factory also uses some lubricating oil additives (such as Keji from Anzhi Chemical Company). When the reducer stops running, the gear oil remains attached to the gear surface, forming a protective film to prevent metal-to-metal contact during heavy loads, low speeds, high torque, and startup. The additives also contain seal conditioners and anti-leakage agents, keeping the seals soft and elastic, effectively reducing lubricating oil leakage.
(3) Selection of the installation location of the reducer. Vertical installation should be avoided if possible. Vertical installation requires significantly more lubricating oil than horizontal installation, which can easily cause the reducer to overheat and leak oil. Some parts of the 40,000 bottles/hour pure draft beer production line introduced by this factory were vertically installed. After a period of operation, the transmission pinions showed significant wear and even damage. After adjustments, the situation was greatly improved.
(4) Establish a corresponding lubrication and maintenance system. The factory maintains the reducers according to the "five fixed points" principle of lubrication work, ensuring that each reducer is inspected regularly by a designated person. If a significant increase in oil temperature is observed during operation, exceeding 40℃ or 80℃, or if the oil quality deteriorates, excessive copper powder is found in the oil, or abnormal noise is generated, operation must be stopped immediately for timely repair, troubleshooting, and replacement of the lubricating oil before reuse. When adding oil, attention must be paid to ensuring the oil quantity and installation position are consistent to guarantee proper lubrication of the reducer.
In summary, hollow shaft worm gear reducers are easy to install, have a reasonable structure, and are reliable and durable. Of course, it's also important to choose the right reducer brand. Reputable companies will consider design considerations such as the reducer's shape, the arrangement of cooling fins, thermal balance calculations, and hydraulic circuit design, combined with the actual use and operating conditions, and employ excellent manufacturing processes to produce high-quality, reliable, and durable reducers. Users can achieve satisfactory results with proper use and maintenance.
