I. Basic composition:
Screw: A shaft with a precision spiral raceway. The raceway section is usually a Gothic arch, which is used to guide and carry the ball.
Nut: A spiral raceway that matches the screw is also machined inside. The nut usually contains a circulation structure.
Ball: A high-precision steel ball that rolls between the raceways of the screw and the nut to transfer load and motion. They are the core of achieving low friction.
Circulation system: The key structure inside the nut (such as the ball returner, end cap circuit, etc.), whose function is to smoothly guide the ball from the end of the raceway back to the starting end after the ball has rolled a circle, forming a continuous, closed circulation path. This is the essential feature that distinguishes the ball screw from the sliding screw.
Dust seal: Prevent external dust, chips and other contaminants from entering the raceway while maintaining internal grease.
II. Working principle:
When one of the screw or nut rotates, the ball rolls in the raceway between the two.
The rolling friction of the balls is much lower than the sliding friction, which significantly reduces the driving torque and heat generation.
The balls circulate continuously in the nut through the circulation system, so that the rotary motion can be continuously and efficiently converted into linear motion (or vice versa).