Solution: How to correctly select the transmission ratio i 12, the number of worm heads z 1 and the number of worm teeth z2? Briefly explain the reasons.

If i 12 is not the value of transmission ratio, your problem is to choose the appropriate transmission ratio. This problem is actually to consider how to choose Z 1 and Z2. Z 1 The main factors to be considered are: efficiency, self-locking and power transmission (of course, meeting the requirements of transmission ratio). Efficiency is usually 1, 2, 3, 4, 6. When the transmission ratio is greater than 40 or self-locking is required, take z1=1; When the transmission power is high, in order to improve the efficiency, Z 1 = 1 ~ 4 is usually taken. But the more heads there are, the more difficult it is to ensure the machining accuracy. Z2 is calculated according to the transmission ratio, which is generally taken as Z2 = 28 ~ 80. When Z2 is less than 28, undercutting is easy to occur, which affects the smooth transmission. If Z2 is too large, the length of the worm engaged with it will increase and the rigidity will deteriorate. The recommended values of Z 1 and Z2 are given in the design manual. You can check it.