Helical Gears MIM Parts

Product Introduction

Worm gear classification
Worm gears generally have these series:
1. WH series worm gear reducer: WHT/WHX/WHS/WHC
2. CW series worm gear reducer: CWU/CWS/CWO
3. WP series worm gear reducer: WPA/WPS/WPW/WPE/WPZ/WPD
4. TP series enveloping worm gear reducer: TPU/TPS/TPA/TPG
5. PW type planar double-enveloping toroidal worm reducer In addition, according to the shape of the worm, the worm transmission can be divided into cylindrical worm transmission, toroidal worm transmission and conical worm transmission.

Characteristics of the institution
1. A large transmission ratio can be obtained, which is more compact than the cross-axis helical gear mechanism.
2. The meshing tooth surfaces of the two wheels are in line contact, and its load-carrying capacity is much higher than that of the cross-axis helical gear mechanism.
3. The worm transmission is equivalent to the screw transmission, which is a multi-teeth meshing transmission, so the transmission is stable and the noise is small.
4. Self-locking. When the lead angle of the worm is smaller than the equivalent friction angle between the meshing teeth, the mechanism is self-locking and can realize reverse self-locking, that is, only the worm can drive the worm wheel, but not the worm wheel. For example, the self-locking worm mechanism used in hoisting machinery, its reverse self-locking property can play a role of safety protection.
5. The transmission efficiency is low and the wear is serious. When the worm gear meshes and drives, the relative sliding speed between the meshing gear teeth is large, so the friction loss is large and the efficiency is low. On the other hand, the relative sliding speed causes serious wear and heat on the tooth surface. In order to dissipate heat and reduce wear, Helical Gears MIM Parts often use relatively expensive materials with good anti-friction and anti-wear properties and good lubrication devices. Therefore, the cost is higher.
6. The axial force of the worm is relatively large.

Application
Worm gears and worm mechanisms are often used in occasions where the two shafts are interlaced, the transmission ratio is large, the transmission power is not large, or the operation is intermittent.

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. Due to the sliding friction transmission, more heat will be generated during operation, which will cause differences in thermal expansion between the parts of the reducer and the seals, thus forming gaps on the mating surfaces, and the lubricating oil will become thinner due to the increase in temperature, which will easily cause leakage. . There are four main reasons for this situation. One is the unreasonable matching of materials; the other is the poor quality of the meshing friction surface; the third is the incorrect choice of lubricating oil addition; the fourth is poor assembly quality and use environment.
2. Worm gear wear. The worm wheel is generally made of tin bronze, and the paired worm material is hardened with 45 steel to HRC45~55, or 40Cr hardened to HRC50~55, and then ground to a roughness of Ra0.8μm by a worm grinder. The reducer wears very 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 use environment and other reasons.
3. Drive pinion helical gear worn. 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. In vertical installation, it is easy to cause insufficient lubricating oil. When the reducer stops running, the transmission gear oil between the motor and the reducer will be lost, and the gears will not be properly lubricated. When the reducer is started, the gears will be mechanically worn or even damaged due to lack of effective lubrication.
4. Damaged worm bearing. When a failure 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 has been running for a period of time, the condensed water produced after the temperature of the gear oil rises and cools down mixes with the oil. Of course, it is also closely related to the bearing quality and assembly process.

Solution
1. Guaranteed assembly quality. You can buy or make some special tools by yourself. When disassembling and installing parts of the reducer, try to avoid hitting with other tools such as hammers; when replacing gears and worm gears, try to use original parts and replace them in pairs; when assembling the output shaft, pay attention to Tolerance fit; anti-sticking agent or red lead oil should be used to protect the hollow shaft to prevent wear and rust or dirt on the mating area, which is difficult to disassemble during maintenance.
2. Selection of lubricants and additives. The worm gear reducer generally uses 220# gear oil. For the reducer with heavy load, frequent start-up and poor use environment, some lubricating oil additives can be used to make the gear oil still adhere to the gear surface when the reducer stops running, forming a protective Membrane to prevent direct metal-to-metal contact during heavy loads, low speeds, high torques and starting. The additive contains sealing ring regulator and anti-leakage agent to keep the sealing ring soft and elastic and effectively reduce the leakage of lubricating oil.
3. Selection of the installation location of the reducer. If the location permits, try not to use vertical installation. In vertical installation, the amount of lubricating oil added is much more than in horizontal installation, which may easily cause heat generation and oil leakage of the reducer.
4. Establish a lubrication maintenance system. The reducer can be maintained according to the "five determinations" principle of lubrication work, so that each reducer has a responsible person to check regularly, and it is found that the temperature rise is obvious, if it exceeds 40°C or the oil temperature exceeds 80°C, the quality of the oil will decline or the oil quality will decrease. When more copper powder and abnormal noise are found in the machine, stop using it immediately, repair it in time, eliminate the fault, and replace the lubricating oil. When refueling, pay attention to the amount of oil to ensure that the reducer is properly lubricated.

Metal Injection Molding Process

Detection Systems