Transmission Principle and Scope of Use of Worm Gear Reducers

1、 Basic parameters of worm gear reducer:

Module m, pressure angle, worm diameter coefficient q, lead angle, number of worm heads, number of worm gear teeth, tooth height coefficient (taken as 1), and top clearance coefficient (taken as 0.2). Among them, the modulus m and pressure angle refer to the modulus and pressure angle of the worm shaft surface, that is, the modulus and pressure angle of the worm gear shaft surface, and both are standard values; The worm diameter coefficient q is the ratio of the worm indexing circle diameter to its modulus m,

2、 The calculation of geometric dimensions is basically the same as that of cylindrical gears, but several issues that need to be noted are:

The worm lead angle () is the angle between the tangent of the helix on the worm indexing cylinder and the end face of the worm. It is related to the helix angle of the screw. If the helix angle of the worm gear is large, the transmission efficiency is high. When it is smaller than the equivalent friction angle between the meshing teeth, the mechanism locks itself.

The introduction of the worm diameter coefficient q is to limit the number of worm gear hobs and standardize the diameter of the worm indexing circle. When m is fixed, q increases, and the stiffness and strength of the worm shaft correspondingly increase; When q is small, the lead angle increases and the transmission efficiency correspondingly increases.

The recommended values for the number of worm heads are 1, 2, 4, and 6. When a small value is taken, its transmission ratio is large and it has self-locking properties; When taking a large value, the transmission efficiency is high.

Unlike cylindrical gear transmission, the transmission ratio of a worm gear mechanism is not equal to, but rather, the center distance of the worm gear mechanism is not equal to.

The determination method of worm gear rotation in worm gear transmission can be based on the direction and direction of the meshing point K (parallel to the tangent of the helix), and the speed vector triangle drawn perpendicular to the worm gear axis; It can also be determined by using the words' right-hand worm with left hand grip, left-hand worm with right hand grip, four thumbs'.

3、 Conditions for Correct Engagement of Worm Gears and Worms

1. The modulus and pressure angle of the worm and worm gear in the middle plane are equal, that is, the end face modulus of the worm gear is equal to the axial surface modulus of the worm and is the standard value; The end face pressure angle of the worm gear should be equal to the axial pressure angle of the worm and be the standard value, i.e.==m==

2. When the staggered angle of the worm gear and worm gear is, it is also necessary to ensure that the direction of rotation of the worm gear and the spiral of the worm gear must be the same.

4、 The characteristics of worm gears and worm gear mechanisms allow for a large transmission ratio, which is more compact than staggered helical gear mechanisms

The meshing tooth surfaces of the two wheels are in line contact, and their load-bearing capacity is much higher than that of the staggered helical gear mechanism

Worm drive is equivalent to screw drive, which is a multi tooth meshing transmission, so the transmission is stable and the noise is very low

It has self-locking properties. When the lead angle of the worm is smaller than the equivalent friction angle between the meshing teeth, the mechanism has self-locking and can achieve reverse self-locking, that is, the worm can only drive the worm gear, not the worm gear. If a self-locking worm mechanism is used in its heavy machinery, its reverse self-locking can provide safety protection

Low transmission efficiency and severe wear. When worm gear is engaged for transmission, the relative sliding speed between the meshing teeth is high, resulting in high friction loss and low efficiency. On the other hand, the relative sliding speed causes severe wear and heat generation on the tooth surface. In order to dissipate heat and reduce wear, expensive materials with good friction and wear resistance and good lubrication devices are often used, resulting in higher costs and higher axial force on the worm

5、 Purpose:

Worm gear and worm mechanisms are commonly used to transmit motion and power between two staggered shafts. The worm gear and worm are equivalent to gears and racks in their middle plane, and the worm is similar in shape to a screw.