Worm and Wheel

Worm and Wheel

Worm transmission(Worm and Wheel) is composed of worm and worm wheel, which is used to transfer the motion and power between the two staggered shafts. Generally, the angle of the two shafts is 90°. In the general worm transmission, the worm is the driving part. In appearance, the worm is similar to the bolt, and the worm gear is similar to the helical spur gear. During work, the worm gear teeth slide and roll along the spiral surface of the worm. In order to improve the contact condition of the gear teeth, the worm gear is formed into circular arc shape along the direction of tooth width, so that it partially covers the worm. In this way, the worm and worm gear are engaged in line contact instead of point contact.

Worm and Wheel Description

If you want a larger gear reduction ratio, you need to use worm gear. The gear reduction ratio of the worm gear is generally 20:1, sometimes as high as 300: 1 or more. Many worm gears have an interesting feature not found in other gear sets: worms can easily turn the gear, but gears cannot turn worms. This is because the protruding angle on the screw is very shallow. When the gear tries to rotate the screw, the friction between the gear and the screw will keep the screw in place.

Properly Meshed

1. The module and pressure angle of the worm and the worm gear in the middle plane are equal, that is, the end module of the worm gear is equal to the axial surface module of the worm and is the standard value; the end pressure of the worm gear should be equal to the axial pressure angle of the worm gear and the worm and is standard value.
2. When the stagger angle of the worm gear is, it must be ensured, and the helical direction of the worm gear and the worm must be the same.

Material

The worm gear are usually made of cast tin bronze and aluminum iron bronze; low speed and non-critical transmissions can be made of cast iron.
1.Cast iron bronze: good friction, good anti-glue, expensive, slightly lower strength.
2.Cast aluminum, iron, bronze: it is slightly poor in friction reduction and anti-glue, but it has high strength and price.
3.Cast iron: grey; ductile. Aging treatment is required to prevent deformation.

Worm and Wheel Features

1. A large transmission ratio can be obtained, more compact than the staggered shaft helical gear mechanism
2. There is linear contact between the meshing tooth surfaces of the two wheels, and its bearing capacity is much higher than that of the staggered shaft helical gear mechanism.
3. The worm drive is equivalent to helical drive. It is a multi-tooth meshing drive, so the drive is stable and the noise is small.
4. With self-locking. When the lead angle of the worm is smaller than the equivalent friction angle between the teeth of the meshing gear, the mechanism is self-locking and can achieve reverse self-locking, that is, the worm can only be driven by the worm, but not by the worm. Such as the self-locking worm mechanism used in its heavy machinery, its reverse self-locking can play a role in safety protection.
5. The transmission efficiency is low and the wear is serious. When the worm gear is meshed and driven, the relative sliding speed between the teeth of the meshing gear is large, so the friction loss is large and the efficiency is low. On the other hand, the high relative sliding speed has serious wear on the tooth surface and severe heated. In order to dissipate heat and reduce wear, more expensive materials with good friction reduction and wear resistance and good lubrication devices are often used, so the cost is higher.
6. The axial force of the worm is large.

Products Show