1) Trapezoidal thread - The tooth profile is an isosceles trapezoid with a tooth angle of 30°. It is the most commonly used transmission thread.
Compared with rectangular thread, the transmission efficiency is slightly lower, but the processability is good, the root strength is high, and the centering is good. The lead screw of the machine tool uses trapezoidal thread to transmit power in both directions. The thread code is represented by T r.
(2) Sawtooth thread - A transmission thread subjected to unidirectional force, the tooth profile is an isosceles trapezoid, the angle between one side and the plumb line is 30°, and the other side is 3°, forming a tooth angle of 33°. Its tooth profile is a sawtooth shape, code B. It is only used to bear unidirectional power. Because its transmission efficiency and strength are higher than those of trapezoidal thread, it is often used in screw presses and hydraulic presses and other unidirectional force-bearing mechanism threads.
(3) Rectangular thread: mainly used for force transmission, its characteristic is that the transmission efficiency is higher than other threads, but the strength is greater, so its application is subject to certain restrictions
(4) Modulus thread: that is, the worm thread, its tooth shape is 40 degrees, it has the characteristics of large transmission ratio, compact structure, stable transmission, good self-locking performance, etc. It is mainly used in reduction devices.