Spline Basics

There are two basic types of spline rolling machines using flat racks in use today. These spline rolling machines are producing a variety of splines, threads, grooves, and clutch housings around the world. The main difference between the two types of rollers is the way that the main slides are driven and synchronized. One type of roller uses two hydraulic cylinders to drive the slides while, timing racks and a timing gear keep the slides synchronized. The other type of spline roller uses two hydraulic piston motors which are connected to a rack and pinion to drive the slides. These machines use a gear train to keep the slides synchronized. There are a few machines out in the world that use the hydraulic piston motors with the timing racks and gear.

Another difference between the two types of spline rollers is the hydraulic power units. The hydraulic cylinder style machines use vane pumps with large directional valves supplying the cylinders with oil to move the slides. The hydraulic piston motor style machines use a closed loop hydraulic system in which a variable pump supplies the hydraulic motors with oil to move the slides.

The slides, fixturing, and tooling on the two style machines are extremely similar. Due to the fact that the functional phases of these machines are so similar, the reference figures used in this manual will be generic.

Both style machines produce the splines, threads, etc., in the same manner. A fixture called a rack box or rack holding fixture (see fig. 2) is mounted on a slide. This fixture technique holds the tooling (commonly known as racks) which produce the splines. There are two opposing slides and rack boxes per machine. The opposing tools traverse over each other while a piece part is held on the center-line of the machine, usually between centers.

The general cycle of the two styles of spline rollers is the same also. There are three basic sequence of operations described in this technical section. The first is for a manually loaded and operated machine. The second is a manually loaded machine with a semi-automatic cycle. The third sequence of operations is for a fully automatic machine.