Conditions for correct engagement of worm:
1. The modulus and pressure Angle of worm and worm wheel in the middle plane are equal respectively, that is, the end face modulus of worm wheel is equal to the axial surface modulus of worm and is the standard value; The end pressure Angle of worm gear should be equal to the axial surface pressure Angle of worm and be the standard value.
2, when the staggered Angle of the worm gear is consistent, it needs to be guaranteed, and the spiral direction of the worm gear and the worm must be the same.
Features:
1. Large transmission ratio, compact structure. The number of worm heads is represented by Z1 (generally Z1=1~4), and the number of worm gear teeth is represented by Z2. From the transmission ratio formula I=Z2/Z1, it can be seen that when Z1=1, that is, the worm is a single head, the worm must turn Z2 to turn the worm wheel, so a large transmission ratio can be obtained, generally in the power transmission, the transmission ratio I=10-80; In the indexing mechanism, I can reach 1000. Such a large transmission such as gear transmission, you need to take multistage transmission, so worm transmission structure is compact, small size, light weight.
2. Smooth transmission, no noise. Because the worm teeth are continuous and uninterrupted spiral teeth, it is continuous when meshing with the worm gear teeth, the worm teeth do not enter and exit the meshing process, so the work is stable, impact, vibration, noise are relatively small.
3. Self-locking. The spiral Angle of the worm is very small, the worm can only drive the worm gear transmission, and the worm wheel can not drive the worm to rotate.
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Conditions for correct engagement of worm:
1. The modulus and pressure Angle of worm and worm wheel in the middle plane are equal respectively, that is, the end face modulus of worm wheel is equal to the axial surface modulus of worm and is the standard value; The end pressure Angle of worm gear should be equal to the axial surface pressure Angle of worm and be the standard value.
2, when the staggered Angle of the worm gear is consistent, it needs to be guaranteed, and the spiral direction of the worm gear and the worm must be the same.
Features:
1. Large transmission ratio, compact structure. The number of worm heads is represented by Z1 (generally Z1=1~4), and the number of worm gear teeth is represented by Z2. From the transmission ratio formula I=Z2/Z1, it can be seen that when Z1=1, that is, the worm is a single head, the worm must turn Z2 to turn the worm wheel, so a large transmission ratio can be obtained, generally in the power transmission, the transmission ratio I=10-80; In the indexing mechanism, I can reach 1000. Such a large transmission such as gear transmission, you need to take multistage transmission, so worm transmission structure is compact, small size, light weight.
2. Smooth transmission, no noise. Because the worm teeth are continuous and uninterrupted spiral teeth, it is continuous when meshing with the worm gear teeth, the worm teeth do not enter and exit the meshing process, so the work is stable, impact, vibration, noise are relatively small.
3. Self-locking. The spiral Angle of the worm is very small, the worm can only drive the worm gear transmission, and the worm wheel can not drive the worm to rotate.
4. Worm transmission efficiency is low, it is generally believed that worm transmission efficiency is lower than gear transmission. In particular, with self-locking worm drive, its efficiency is below 0.5, and the general efficiency is only 0.7 to 0.9.
5. The heat is large, the tooth surface is easy to wear and the cost is high.
Transmission application:
Worm drive is often used in two axes staggered, relatively large transmission, transmission power is not too large or intermittent work occasions. When a large power is required to be transferred, in order to improve transmission efficiency, Z1=2 ~ 4 is often used. In addition, because the drive has self-locking when γ1 is small, it is often used in lifting machinery such as winches to play a safety protection role. It is also widely used in machine tools, automobiles, instruments, metallurgical machinery and other machines or equipment, the reason is because the use of axle movement can reduce the consumption of force, so as to vigorously promote.
