Tech Tips from NB Corp

Ball screw splines are a combination of two components: a rotary ball screw nut and a ball spline nut. Both components are attached to a grooved shaft to provide linear, rotary, or spiral motion. They’re compact, reliable, and used in robot arms.

Knowing the benefits of ball screw splineswill help determine if this line suits your application.

How a ball screw spline provides smooth motion

A ball screw spline combines a driven-nut-type ball-screw assembly with a rotary ball spline. The shaft of the ball-screw spline has screw threads and spline grooves along its length, with the grooves and threads crossing each other. As the shaft rotates, the interaction between the threads on the shaft and the grooves on the nut drive it linearly. The balls trapped between the grooves and the threads allow smooth motion by reducing friction and providing rolling contact.

Two types of spline nut

NB Corp. offers two types of ball screw splines. Both have a rotary ball screw nut, which is essentially an assembly made of a ball spline nut and angular contact bearings.

The SPBR ball screw spline uses a rotary ball spline nut component, which includes a ball spline nut and angular contact bearings. The SPBF ball screw spline has a non-rotary or fixed ball spline nut on a single shaft. This lets rotary inputs on the ball screw move linearly.

Three kinds of motion

Ball screw spline assemblies constrain the ball screw nut and ball spline nut from moving linearly. By driving the ball nut and spline nut together or separately, three different types of motion can be produced: linear, rotary, and spiral.

It’s lighter so it’smore accurate

The accuracy of ball screw splines comes from precision machining and a rigid fit. A ball screw spline weighs less than a ball screw and separate shaft, so robots and other machines with a spline mounted on the end of an arm can move it with less energy and more accuracy.

Ball screw splines versus ball splines

Ball screw splines combine a rotary ball screw nut and a ball spline on a single shaft, allowing linear actuation, torque transfer, and rotational motion with a single compact assembly. They weigh less and are smaller than linear-motion assemblies made from several components, making them ideal for small spaces.

Ball splines have a spline nut riding on a shaft with grooves along its length. The spline nut consists of an outer cylinder (main body), retainer, side rings, and ball elements and is designed and manufactured to achieve a reliably smooth motion. It uses the rolling motion of ball elements to sustain loads and transfer torque. Ball splines have good load-carrying capacity but maybe not as much as that of a ball screw spline.

A rotary ball spline, used for rotational and linear motion, consists of a spline nut and a rotating portion that uses either cross rollers or balls. Ball splines transfer torque and achieve accurate positioning in the linear direction. By adding a rotating portion, rotary ball splines can achieve accurate positioning in the linear and rotational directions.

For more Information:
NB Corp.
https://www.nbcorporation.com