What is Worm Gear?
What is Worm Gear?
The worm-cutting method can be divided into lathe (shaft right angle method) or milling machine cutting (tooth right angle method), which can be achieved by selecting an appropriate milling cutter or turning tool. The worm has a rod-shaped gear with single or multiple threads. The multi-head is also a type of helical gear. The gear that meshes with the worm is called a worm wheel. The modulus and pressure angle of the worm and worm gear is in the case of spur gears, the tooth right angle and the shaft right angle are equal, in the case of helical gears or (worm and worm gear), the modulus and pressure angle must add a conditional factor, which is the generation of the helix angle, the modulus and pressure angle need to be divided by cosγ as the difference between the tooth right angle and the shaft right angle, that is the projection angle γ.
A worm drive is a gear train composed of a worm gear and a worm. Worm wheels and worms are sometimes referred to as worm wheels and worm screws. Sometimes worm refers to the worm itself, sometimes it refers to the entire gear train, and the same is true for worm gears.
A transmission consisting of a worm and worm gear will be much smaller than a face gear, and the input and output shafts will be perpendicular to each other. If it is a single-thread worm, the worm wheel will only advance one step when the worm rotates 360 degrees. So regardless of the size of the worm (leaving aside practical engineering constraints). The reduction ratio is worm gear teeth: 1. Assuming a single-thread worm with a 20-tooth worm gear, the reduction ratio is 20:1. If it is a transmission mechanism composed of gears, the 12-tooth small gear must cooperate with the 240-tooth large gear to have a 20:1 deceleration. Therefore, if the diameter pitch (DP) of the gear is constant, considering the volume difference between the 240-tooth large gear and the 20-tooth worm gear, the worm drive mechanism will be much smaller than the gear drive mechanism.
The Efficiency of the Worm Gear Set:
Although the transmission efficiency of the worm gear set will vary with the assembly situation and lubricating oil, etc., However, without calculating the bearing loss and the stirring loss of lubricating oil, the worm is taken as active transmission, its efficiency is about 30~90%.
The structure and adjustment method of worm gear backlash adjustment:
The lead lengths of the left tooth surface and the right tooth surface of the worm are different, resulting in the pitch between the right tooth surface and the pitch between the left tooth surfaces being different. Therefore, due to the difference in the lead, the tooth thickness becomes non-constant fixed, which is a tooth shape with continuous change in tooth thickness. The tooth surface of the worm wheel is also made into different tooth surfaces on the left and right to cooperate with the worm.
Since the worm gear is a spur gear, all tooth surfaces have the same pitch. After the worm and worm gear like this are assembled under a certain assembly distance if the worm is along the axial direction.
When moving in the opposite direction, since the tooth thickness of the worm in the meshing part changes, the adjustment of the backlash
The advantages of using the worm and worm gear combination are:
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