Comparison of rack drive and screw drive
June 17, 2022
The screw drive has high precision and high cost.
However, under long-distance heavy loads, the screw is liable to cause bending. The rack does not have these conditions.
In the transmission process, the rack and pinion will have their own unique movement characteristics: the gear transmission is used to transmit the motion and power between any two axes, its peripheral speed can reach 300m/s, the transmission power can reach 105KW, and the gear diameter can be Less than 1mm to 150m, it is the most widely used mechanical transmission in modern machinery.
Compared with the belt drive, the rack and pinion drive has the following advantages:
(1) The characteristics of large power transmission and effective gear transmission. Gear transmission is used to transfer the motion and power between any two axes. Its peripheral speed can reach 300m/s, transmission power can reach 105KW, and gear diameter can be from less than 1mm to more than 150m. It is the most widely used type in modern machinery. Mechanical transmission.
(2) long life, stable operation and high reliability;
(3) It can ensure a constant transmission ratio and can transmit the movement between two axes at any angle.
The main disadvantages of screw drive and gear drive are:
(1) The requirements for manufacturing and installation accuracy are high, and the cost is also high;
(2) It is not suitable for long distance transmission.
The screw transmission mechanism includes a screw rod and a jacket. A stopper pin is arranged at the end of the screw rod, a ball is embedded in the thread groove, and the ball fits tightly with the inner surface of the jacket. The inner sleeve is also sleeved between the jacket and the screw rod. Between the inner sleeve and the outer sleeve, there is only one degree of freedom of rotation around the axis of the screw rod, the inner sleeve is provided with a through hole, the inner sleeve end is provided with a rib, and the extension direction of the rib is parallel to the axis of the screw rod. The screw of the transmission mechanism can drive the outer sleeve to move axially within the normal stroke range, and after the outer sleeve moves to the end of the stroke, the screw rod can continue to rotate and the outer sleeve can automatically stop the axial movement, with simple and reliable advantages. .
Screw drive has high precision and high cost.
However, under long-distance heavy loads, the screw rod easily causes bending. The rack does not have these conditions.
Generally more than 6 meters is recommended to use the rack. The accuracy of the screw is indeed better than the rack, which depends on your load and span conditions. Now the rack also has a lot of anti-backlash means to make up for the problem of accuracy.
