Worm GearThe structure is often used to transmit the motion and power between two cross-axis. The worm wheel and the worm are equivalent to the gear and the rack in the middle plane, and the worm and the screw are similar in shape.

Features of worm gear mechanism:

1. A large transmission ratio can be obtained, which is more compact than the cross-shaft helical gear mechanism.

2. The worm drive is equivalent to a spiral drive, which is a multi-tooth meshing drive, so the transmission is stable and the noise is small.

3. The meshing tooth surfaces of the two wheels are in line contact, and its carrying capacity is much higher than that of the cross-axis helical gear mechanism.

4. Self-locking. When the lead angle of the worm is smaller than the equivalent friction angle between the meshing gear teeth, the mechanism is self-locking and can realize reverse self-locking, that is, only the worm can drive the worm wheel, but the worm wheel cannot drive the worm. For example, the self-locking worm mechanism used in hoisting machinery, its reverse self-locking property can play a safety protection role.

5. The axial force of the worm is large.

6. Low transmission efficiency and serious wear. When the worm gear is engaged in transmission, 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 means that the tooth surface wears seriously and heats up. In order to dissipate heat and reduce wear, more expensive materials with better anti-friction and anti-wear properties and good lubricating devices are often used, so the cost is higher. .

What materials are generally used for worms and worm wheels? Why?

Under normal circumstances, the worm is the driving wheel, and the material is high-density alloy steel, which is not easy to wear; the worm wheel is the driven wheel and the material is bronze.

The worm gear uses bronze as the raw material because:

1. Bronze has a lubricating effect, which helps reduce friction.

2. The bronze texture is relatively soft. Generally, the material of the worm is harder than the worm wheel. The worm wheel is a passive wheel. The worm is the driving wheel and is generally connected to the motor. If the equipment fails to rotate, the motor can damage the soft worm through the worm. , To protect the motor from being burnt out.