What’s the Ball Screw?
Ball screw is a component that uses balls instead of sliding. It is a transmission component of the machinery. Its main function is to convert rotary motion into linear motion, or convert torque into axial repetitive force.
As we known, the parts touch each other will generate friction, which will consume a certain amount of energy, reduce work efficiency, and damage mechanical equipment. Using balls is an effective way to reduce friction of parts. So ball screws are widely used in various industrial equipment and precision instruments, including the SMT Pick and Place Machine.
A ball screw consists primarily of a threaded rod and a nut, each with matching helical grooves, and balls that roll between these grooves, providing the only contact between the nut and the threaded rod, and when the threaded rod rotates relative to the nut, the rotation of the screw causes the balls to push the nut to move axially, and at the same time, the ball rolls along the helical groove, so that the sliding friction between the screw and the nut is transformed into the rolling friction between the ball and the screw & nut. The balls are returned from one end to the other through a return system, forming a continuous loop in a closed loop.
There are two types of ball circulation, outer circulation and inner circulation.
The outer circulation is that the balls re-enter the circulation through the spiral groove on the outer surface of the nut or the cannula return to the screw & nut, after the end of the circulation process. The structure and manufacturing process of the outer circulation are simple and widely used, but the disadvantage is that the joint of the spiral groove is difficult Do it smooth and affect the smoothness of the ball.
The inner circulation adopts the reverser to realize the ball circulation, but the outer contour of the reverser and the dimensional accuracy of the groove on the nut are relatively high, and the balls in the spiral groove reduce the mechanical contact inside the screw assembly and replace sliding friction with rolling friction. This unique design significantly reduces friction and enables efficient mechanical movement.
Compared with ordinary sliding parts, the ball screw has a more complex structure and higher cost, but it has higher precision and can improve efficiency and load, and is mainly used for precise positioning.