What Are the Basics of Worm-Gear Design?

Worm gears are commonly used to transfer motion and power between two staggered axes. Worms and worms are equivalent to gears and racks in the middle plane, and worms are similar in shape to screws.

Modulus m,

classification

There are roughly these series of worm gears: 1. WH series

Turbine shaft

I. Common problems and their causes

1. Reducer heat and oil leakage. In order to improve efficiency, worm gear reducers generally use non-ferrous metals as worm gears, and worms use harder steel. Because it is a sliding friction transmission, more heat is generated during operation, which causes differences in thermal expansion between the parts of the reducer and the seal, thereby forming gaps on each mating surface. The lubricant fluid becomes thinner due to the increase in temperature, which is likely to cause leakage . There are four main reasons for this situation. One is the unreasonable combination of materials; the other is the poor quality of the meshing friction surface; the third is the incorrect selection of the amount of lubricant added; the fourth is the poor assembly quality and the use environment. 2. Worn gear. The worm gear is generally made of tin bronze. The matched worm material is hardened with 45 steel to HRC45 ~ 55, or 40Cr hardened HRC50 ~ 55 and then ground to a roughness Ra0.8m by a worm grinding machine. Reducers wear slowly during normal operation, and some reducers can be used for more than 10 years. If the wear speed is fast, it is necessary to consider whether the selection is correct, whether it is overloaded, and the material of the worm gear, assembly quality or the use environment. 3 Worn drive pinion gear. It usually occurs on a vertically installed reducer, which is mainly related to the amount of lubricant added and the type of oil. In vertical installation, it is easy to cause insufficient lubricant quantity. When the reducer stops running, the transmission gear oil between the motor and the reducer is lost, and the gears cannot get the proper lubrication protection. When the reducer is started, the gears are mechanically worn or even damaged due to the lack of effective lubrication. 4 Worm bearing is damaged. When a failure occurs, it is often found that the gear oil in the reducer is emulsified, and the bearings are rusted, corroded, and damaged, even if the reduction box is well sealed. This is because the condensate generated after the gear oil temperature rises and cools after the reducer runs for a period of time is mixed with the oil. Of course, it is also closely related to bearing quality and assembly process. ^[1]

Solution

1. Guarantee assembly quality. You can buy or make some special tools. When removing and installing the reducer components, try to avoid hitting with other tools such as hammers. When replacing gears, worms and worms, try to use original accessories and replace them in pairs. When assembling the output shaft, pay attention to Tolerance fit; use anti-adhesive or red tan oil to protect the hollow shaft, prevent wear and rust or fit area dirt, and it is difficult to disassemble during maintenance. 2. Selection of lubricants and additives. The worm gear reducer generally uses 220 # gear oil. For heavy load, frequent startup, and poor use of the reducer, some lubricant additives can be selected to keep the gear oil on the surface of the gear when the reducer stops running, to protect Membrane to prevent direct contact between heavy loads, low speeds, high torques and metals during startup. The additives contain seal ring regulators and anti-leak agents, which keep the seal ring soft and elastic, and effectively reduce lubricant leakage. 3 Selection of installation position of reducer. Where possible, vertical installations should be avoided. In vertical installation, the amount of lubricant added is much more than in horizontal installation, which may cause heat and oil leakage of the reducer. 4 Establish a lubrication maintenance system. The reducer can be maintained according to the "five set" principle of lubrication work. Every reducer must be inspected regularly by the responsible person. It is found that the temperature rise is obvious, exceeding 40 ° C or the oil temperature exceeds 80 ° C. When more copper powder is found in the system and abnormal noise occurs, stop using it immediately, repair it in time, remove the fault, and replace the lubricant. When refueling, pay attention to the amount of oil to ensure that the reducer is properly lubricated. ^[1]