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    What is a Worm Gearbox?

    A worm gearbox, also known as a worm gear reducer, is a power transmission mechanism that uses the speed converter of the gear to reduce the number of revolutions of the motor to the desired number of revolutions and obtain a larger torque mechanism. Worm gearboxes have various applications, from automotive and heavy machinery to industrial automation and robotics. In this blog, ATO will discuss what is a worm gearbox, its characteristics, common problems, and solutions.

    Worm gearbox

    What is the worm gearbox?

    The worm gearbox is a type of gear system used to transmit power and motion between two non-intersecting shafts. Its basic structure is mainly composed of transmission parts worm gear, shaft, bearing, box, and accessories. It can be divided into three basic structural parts: box, worm gear, bearing, and shaft combination. The box body is the base of all accessories in the worm gear reducer and is an important accessory to support the fixed shafting components, ensure the correct relative position of the transmission parts and support the load acting on the reducer. The worm gear mainly transmits the motion and power between the two staggered shafts, and the main function of the bearing and shaft is power transmission, operation, and improving efficiency. 

    In the mechanism used to transmit power and motion, the application range of reducers is quite extensive. It can be seen in the transmission system of various machinery, from ships, automobiles, locomotives, heavy machinery used in construction, processing machinery, and automatic production equipment used in the machinery industry, to common household appliances and clocks in daily life, etc. Its application can be seen in the application of reducer from the transmission work of large power to a small load and precise angle transmission. In industrial applications, the reducer has the function of deceleration and torque increase and is a widely used device for speed and torque conversion.

    The functions of the reducer mainly include: Reducing the speed while increasing the output torque, and the torque output ratio is according to the motor output multiplied by the reduction ratio, but pay attention not to exceed the rated torque of the reducer. Deceleration reduces the inertia of the load at the same time, and the reduction of inertia is the square of the reduction ratio.

    Features of the worm gearbox

    1. The structure of the worm gear reducer is very compact, its volume is also very light, and its shape is relatively ingenious. It has the characteristics of small size but high efficiency, good heat dissipation, and good heat exchange. 
    2. The worm gearbox is also relatively easy to install, it has the characteristics of flexibility, along with the benefits of easy maintenance. Its advantages also include stable transmission, low noise, and durability.
    3. The worm gearbox also has the characteristic of relatively large output torque. And the practical range is very large, which has high safety and reliability. 

    Common problems and solutions

    1. Common faults of worm gearboxes

    Heating and oil leakage of the reducer: In order to improve efficiency, worm gearboxes generally use non-ferrous metal as worm gears, and worms use harder steels. Because it is a sliding friction transmission, more heat will be generated during operation, so that the thermal expansion between the parts of the reducer and the seal is different, so as to form a gap in each mating surface, and the lubricating oil fluid becomes thinner due to the increase in temperature, which is easy to cause leakage.

    There are four main reasons for this situation, the first is the unreasonable collocation of materials; the second is the poor quality of the meshing friction surface; the third is the incorrect choice of the amount of lubricant added; the fourth is the poor quality of assembly and use of the environment.

    Wear of worm gears: The worm gear is generally made of tin bronze, and the paired worm material is generally hardened to HRC45-55 with No. 45 steel and hardened to HRC50-55 with No. 40 steel, which is ground to roughness Ra0.8μm by worm grinder. When the reducer runs normally, the worm is like a hardened "file", which keeps filing the worm gear and makes the worm gear wear. Generally speaking, this kind of wear is very slow, and some reducers can be used for more than 10 years. If the wear speed is fast, it is necessary to consider whether the type selection of reducer is correct, whether there is overload operation, the material of worm gear, assembly quality or use environment, etc. 

    Wear of transmission small helical gear: It usually occurs on a vertically installed reducer, and it is mainly related to the amount of lubricating oil added and the type of oil. When installed vertically, it is easy to cause insufficient lubricating oil. When the worm gear reducer stops running, the transmission gear oil between the motor and the reducer will be lost, and the gears will not be properly lubricated and protected. When the reducer is started, the gears will be mechanically worn or even damaged due to a lack of effective lubrication.

    Damage of worm bearing: When a fault occurs, even if the gearbox is well sealed, 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 is running for a period of time, the condensate produced after the gear oil temperature rises and cools is mixed with water. Of course, it is also closely related to bearing quality and the assembly process.

    2. Solutions to malfunctions

    Ensure assembly quality: You can buy or make some special tools. When disassembling and installing reducer parts, try to avoid knocking with other tools such as hammers; When replacing gears and worm gears, try to choose original accessories and replace them in pairs; When assembling the output shaft, pay attention to tolerance fit; To use anti-sticking agent or red lead oil antirust paint to protect the hollow shaft, to prevent wear and rust or fouling of the mating area, difficult to disassemble during maintenance. 

    Selection of lubricants and additives: 220# gear oil is generally selected for the worm gear reducer. For worm gear reducers with a heavy load, frequent start, and poor use environment, some lubricating oil additives can be selected to make the gear oil still adhere to the gear surface when the reducer stops running, forming a protective film to prevent direct contact between metals during heavy load, low speed, high torque, and start. The additive contains a sealing ring regulator and anti-leakage agent, which keeps the sealing ring soft and elastic and effectively reduces lubricating oil leakage. 

    Selection of installation position of worm gear reducer: If the location permits, try not to use vertical installation. During vertical installation, the amount of lubricating oil added is much more than that of horizontal installation, which is easy to cause heat generation and oil leakage of the reducer.

    Establish a good lubrication maintenance system: Each reducer should be regularly inspected by the responsible person, and when it is found that the temperature rise is obvious, exceeding 40 °C or the oil temperature exceeds 80 °C, the quality of the oil is reduced or more copper powder is found in the oil and abnormal noise is generated, it should be stopped immediately, overhauled in time, troubleshooting and lubricating oil should be replaced. When refueling, pay attention to the amount of oil to ensure that the worm gear reducer is properly lubricated.

    In conclusion, worm gearboxes are an essential component in many industries, providing a reliable and efficient means of transferring power and motion. With their many applications and benefits, worm gearboxes will likely continue to play an important role in a variety of industries for years to come.

    ATO industrial automation has launched different worm gearboxes with center distances as small as 30mm, 40mm, and 50mm, and as large as 130mm and 150mm, etc. A variety of options are still available for you to choose from. Contact us for purchase now.

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