How A Ball Spline Works?

Ball spline is a precision linear motion part that combines linear motion and rotary motion efficiently. Through the circulating rolling of balls between spline shaft and spline nut, it can realize high precision and low friction linear motion and torque transmission.

1. Main components:

Spline shaft: a hardened precision steel shaft, the outer surface of which is machined with several semi-circular rolling tracks along the axial direction.

Spline nut: the component mounted on the spline shaft, the inner hole surface is also machined with a rolling track corresponding to the spline shaft.

Ball: High precision steel ball, filled between the spline shaft and spline nut rolling track, as the force transmission medium and rolling body.

Returner: A key component that creates a closed-loop path for the balls within the spline nut. When a ball rolls out from one end, the returner guides it back to the starting point, enabling continuous rolling.

Sealing end cover and sealing ring: to prevent dust, chips and other foreign bodies from entering and to maintain the internal grease.

2. Work process:

Transmission torque:

When the spline nut is driven to rotate, the torque is transmitted to the ball through the spline nut.

The ball is "clamped" between the raceway of the spline shaft and the spline nut, so the torque is smoothly transmitted to the spline shaft through the rolling of the ball.

The process is like the nut part of a ball screw, but here it is transmitting pure torque, not converting rotation into linear motion.

Enable straight-line motion:

Because the spline nut is "sitting" on the spline shaft by the ball, there is a low friction rolling contact between them.

When a spline nut (or spline shaft) is subjected to an axial force, the spline nut can easily and precisely slide along the spline shaft.

This linear motion is completely independent of the above rotation and can be carried out simultaneously or separately.

3. Summary of core features:

High precision: the contact mode of the ball eliminates the back gap of the ordinary sliding spline, and the positioning accuracy and repeatability are very high.

High rigidity: can withstand large radial force, torque and bending moment, not easy to deform.

Low friction, high efficiency: rolling friction is far less than sliding friction, smooth motion, less energy loss.

Long life: low contact stress and very slow wear.

Compound movement: the ability to perform smooth rotational and linear movements simultaneously or separately.

When the equipment has high requirements for motion accuracy, efficiency, rigidity and life, and needs to process both rotation and linear motion at the same time, ball spline is a very ideal and efficient solution.

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