(Worm gear and worm reducer) is a kind of transmission machinery with a compact structure and a large transmission ratio. Under specific conditions, it also has a self-locking function. Among them, the hollow shaft type worm gear reducer not only has the above advantages, but also is convenient to install and has a reasonable structure, and thus has been increasingly widely used. It is a multi-stage reducer formed by adding a helical gear reducer at the input end of the worm gear and worm reducer. It can obtain an extremely low output speed. Compared with a single-stage worm reducer, it has higher efficiency, less vibration, lower noise and less energy consumption.
I. Common problems and their causes
1. Heating and oil leakage of the reducer
To improve efficiency, the worm gear is usually made of non-ferrous metals, while the worm is made of steel with higher hardness. Due to its transmission mode of sliding friction, a large amount of heat is generated during operation, resulting in gaps in the mating surfaces due to different degrees of thermal expansion of various components and seals of the reducer. As the temperature rises, the lubricating oil becomes thinner, which easily leads to leakage.
The main reasons for this situation include the following: First, the material combination is inappropriate; second, the surface quality of the meshing friction surface is poor; third, the selection of the amount of lubricating oil added is inaccurate; finally, the assembly quality is poor and the use environment is not ideal.
Personal understanding: This means that in the design and manufacturing process of the reducer, a deep understanding of the characteristics of the materials is required to ensure that they can match each other in terms of friction and thermal expansion. At the same time, optimizing the assembly process and improving the use environment are also the key to solving the problem.
2. Worm gear wear
The worm gear is generally made of tin bronze, and the paired worm material is often 45 steel quenched to HRC45 – 55, or 40Cr quenched to HRC50 – 55 and then ground on a worm grinding machine to a roughness of Ra0.8μm. During the normal operation of the reducer, the wear of the worm gear is extremely slow, and some reducers can even be used for more than ten years. However, if the wear rate is fast, factors such as whether the selection is appropriate, whether there is overload operation, the material of the worm gear and worm, the assembly quality or the use environment need to be considered.
Personal understanding: This indicates that correct selection and reasonable use are crucial for extending the life of the worm gear. In addition, high-quality materials and exquisite assembly technology can significantly reduce wear and improve the service life of the reducer.
3. Wear of the transmission pinion gear
Such wear usually occurs on vertically installed reducers and is mainly related to the amount of lubricating oil added and the type of oil. When installed vertically, it is very easy to cause insufficient lubricating oil. When the reducer stops running, the transmission gear oil between the motor and the reducer will be lost, making the gears unable to obtain the due lubrication protection. When the reducer starts, the gears may suffer mechanical wear or even damage due to lack of effective lubrication.
Personal understanding: This reminds us to be extremely cautious when choosing the installation method and lubricating oil to ensure continuous and sufficient lubrication for the gears to reduce wear and failure.
4. Worm bearing damage
Even if the gearbox is well sealed, when a fault occurs, it is often found that the gear oil in the reducer is emulsified, and the bearings are rusted, corroded and damaged. This is because after the reducer operates for a period of time, the temperature of the gear oil first rises and then cools, resulting in the mixture of condensed water and water. Of course, this is also closely related to the quality of the bearings and the assembly process.
Personal understanding: This emphasizes the importance of focusing on the quality when choosing bearings and strictly following the process requirements during the assembly process to ensure the normal operation and service life of the bearings.
II. Solutions
1. Ensure assembly quality
Some special tools can be purchased or made by oneself. When disassembling and installing the components of the reducer, tools such as hammers should be avoided as much as possible; when replacing gears, worm gears and worms, original factory parts should be selected as much as possible and replaced in pairs; when assembling the output shaft, pay attention to the tolerance fit; anti-sticking agent or red lead oil can be used to protect the hollow shaft to prevent wear, rust or fouling of the mating area, and avoid difficulty in disassembly during maintenance.
Personal understanding: A meticulous assembly process and the selection of high-quality accessories can effectively improve the performance and stability of the reducer and reduce problems caused by improper assembly.
2. Selection of lubricating oil and additives
Worm gear reducers usually use 220# gear oil. For reducers with heavy loads, frequent starts and harsh use environments, some lubricating oil additives can be selected. In this way, when the reducer stops operating, the gear oil can still adhere to the gear surface to form a protective film to prevent direct contact between metals during heavy loads, low speeds, high torques and starts. The seal ring regulators and anti-leakage agents contained in the additives can keep the seal ring soft and elastic, effectively reducing the leakage of lubricating oil.
Personal understanding: Appropriate lubricating oil and additives can not only protect the components of the reducer, but also improve its sealing performance and reduce leakage and wear.
3. Selection of the installation position of the reducer
When the position permits, try to avoid vertical installation. Because when installed vertically, the amount of lubricating oil added needs to be much more than that of horizontal installation, which easily causes the reducer to heat up and leak oil.
Personal understanding: A reasonable choice of installation position can reduce the operational risk of the reducer and improve its working efficiency and service life.
4. Establish a lubrication maintenance system
The reducer can be maintained according to the “five fixed” principle of lubrication work to ensure that each reducer has a dedicated person responsible for regular inspection. Once it is found that the temperature rise is significantly more than 40℃ or the oil temperature exceeds 80℃, the quality of the oil deteriorates, there is a lot of copper powder in the oil, or abnormal noise occurs, etc., the use should be stopped immediately, and timely maintenance and troubleshooting should be carried out, and the lubricating oil should be replaced. When refueling, pay attention to the amount of oil to ensure that the reducer is properly lubricated.
Personal understanding: Regular inspection and maintenance are important measures to prevent faults of the reducer, which can detect problems in time and take corresponding solutions to extend the service life of the reducer.