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 also easy to install and have a reasonable structure, making them one of the most commonly used reducers. A worm gear reducer is a multi-stage reducer created by adding a helical gear reducer to the input end of the worm gear reducer. It can achieve very low output speeds, has higher efficiency than a single-stage worm gear reducer, and also exhibits low vibration, low noise, and low energy consumption.
I. Common Problems and Their Causes
1. Gearbox overheating and oil leakage
To improve efficiency, worm gear reducers typically 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 heat causes differences in thermal expansion between the reducer's components and seals, creating gaps at the mating surfaces. The lubricating oil thins due to the increased temperature, making leakage more likely. There are four main reasons for this: inappropriate material combinations, poor surface quality of the meshing friction surfaces, incorrect selection of lubricating oil dosage, and poor assembly quality and operating environment.
2. Worm gear wear
Worm gears are typically made of tin bronze, while the mating worm is usually made of 45 steel hardened to HRC45-55, or often 40 steel 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 faster, 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 typically occurs in vertically mounted speed reducers, primarily related to the amount and type of lubricating oil added. Vertical mounting easily leads to insufficient lubricating oil. When the speed reducer stops, the transmission gear oil between the motor and the speed reducer leaks out, leaving the gears without proper lubrication and protection. When the speed reducer starts, the gears, lacking effective lubrication, experience mechanical wear or even damage.
4. Worm bearing damaged
When a malfunction occurs, even if the gearbox is well-sealed, it is still common to find that the gear oil inside the gearbox is emulsified, and the bearings are rusted, corroded, and damaged. This is because after the gearbox has been running for a period of time, the gear oil temperature rises and then cools down, producing condensation that mixes with water. Of course, it is also closely related to the quality of the bearings and the assembly process.
II. Solutions
1. Ensure assembly quality
You can purchase or make some special tools. When disassembling and installing reducer parts, try to avoid hitting them with hammers or other tools. When replacing gears, worm gears, or worm shafts, try to use original parts and replace them in pairs. When assembling the output shaft, pay attention to tolerance matching. Use anti-sticking agent or red lead oil to protect the hollow shaft and prevent wear, rust, or scale buildup on the mating surfaces, which would make disassembly difficult during maintenance.
2. Selection of Lubricating Oil and Additives
Worm gear reducers generally use 220# gear oil. For reducers subjected to heavy loads, frequent starts, or harsh operating environments, some lubricating oil additives can be used. These additives ensure that the gear oil remains adhered to the gear surface when the reducer stops, forming a protective film to prevent direct metal-to-metal contact under heavy loads, low speeds, high torque, and during startup. The additives contain seal conditioners and anti-leakage agents, keeping the seals soft and elastic, effectively reducing lubricating oil leakage.
3. Selection of the installation location for the speed reducer
If location permits, avoid vertical installation. Vertical installation requires more lubricating oil than horizontal installation, which can easily cause the gearbox to overheat and leak oil.
4. Establish a lubrication and maintenance system.
The reducer can be maintained according to the "five fixed points" principle of lubrication work, ensuring that each reducer has a responsible person for regular inspection. If a significant temperature rise is found, exceeding 40℃ or the oil temperature exceeds 80℃, or if the oil quality deteriorates, or if a large amount of copper powder is found in the oil, or if abnormal noise is generated, use should be stopped immediately, and timely repairs should be carried out to eliminate the fault and replace the lubricating oil. When adding oil, pay attention to the oil level to ensure that the reducer receives proper lubrication.
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