The difference between the worm gear pair and ordinary worm gear pair of planetary reducer variable lead worm gear reducer is that the left and right sides of the variable lead worm tooth have different leads, while the lead of the same side is equal. Because the tooth thickness of the worm gradually increases or decreases evenly from one end of the worm to the other end, the variable lead worm is also called the variable tooth thickness worm. Therefore, the meshing clearance of worm gear pair can be eliminated or adjusted by the method of moving the worm axially.

The working principle of variable lead worm gear pair of worm gear planetary reducer
The difference between the worm gear pair of the variable lead worm gear reducer and the common worm gear pair is that the left and right sides of the variable lead worm tooth have different leads, while the lead of the same side is equal. Because the reducer worm tooth thickness from one end to the other end of the worm evenly gradually thickening or thinning, so the variable lead worm is also known as the variable tooth thickness worm. Therefore, the meshing clearance of worm gear pair can be eliminated or adjusted by the method of moving the worm axially.

The meshing principle of double lead worm gear pair is the same as that of general worm gear reducer. The axial section of the worm acts as a basic rack, and the worm gear acts as the gear with which it engages. Although the left and right sides of the worm teeth have different pitch (that is, different modulus), the same pitch on the same side does not destroy the meshing condition. When the worm is moved axially, good meshing can be guaranteed.

Two, the characteristics of double lead worm gear pair

The double lead worm gear pair is widely used in CNC machine tools with rotating feed motion or indexing motion because it has the following outstanding advantages.
(1) Meshing clearance can be adjusted very small. According to experience, the backlash can be adjusted to 0.01~0.015mm, while the common worm gear pair can only reach 0.03~0.08mm in general, and it is easy to bite to death if it is small. Therefore, the variable lead worm gear pair can work under a smaller backlash, which is very beneficial to improve the indexing accuracy of the CNC turntable.

(2) Ordinary worm gear pairs adjust the meshing backlash by radial movement of the worm, so as to change the center distance of the transmission pair. From the perspective of the meshing principle, it is unreasonable because changing the center distance will cause worse tooth contact, or even aggravate wear, which is not conducive to maintaining the accuracy of the worm gear pair. The variable lead worm gear pair uses the worm to move axially to adjust the meshing backlash without changing the center distance.

(3) double lead worm is used to adjust the grinding ring to control the amount of adjustment, adjustment is accurate, convenient and reliable; But the radial adjustment of common worm gear pair is difficult to master, and it is easy to produce worm axis skew during adjustment.

(4) the worm of the double lead worm gear pair of planetary reducer is supported on the support, and only need to ensure that the supporting center line and the worm gear cross section overlap, and the center distance tolerance can be slightly relaxed. When assembling, the adjusting ring is used to obtain the appropriate meshing clearance, which is not possible for the ordinary worm gear pair.