What Is an Involute Spline?
An involute spline is an element whose tooth profile is formed using an involute curve. It is more precise than elements using general keyways and can transmit greater torque.
Spline is a fastening element that transmits power by meshing structures with external and internal teeth cut into each other. The fundamental principle is similar to that of gears (spur gears), where external teeth mesh together.
In Japan, an involute spline is standardized by JIS. When considering the assembly of an involute spline into a mechanical device, it is necessary to confirm that it conforms to the JIS standard.
Uses for Involute Splines
Compared to other splines like square splines and serrations, involute splines are easier and more precise to manufacture, making them widely used in mechanical devices.
For example, they are used in gearboxes for automobiles and motorcycles, where gears slide along the shaft to change speeds.
On the other hand, machining involute splines require a tooth height of a certain height, so it is not suitable for thin shafts or thin-walled shafts. In such cases, using a serrated type will enable stable rotation.
Principles of Involute Splines
The characteristic tooth profile of an involute spline is formed by drawing a specific curve known as an “involute curve.”
Wrap a thread around the cylinders circumference and attach a pencil to the end of the thread. Unwind the thread from its taut state and draw the trajectory of the thread with the pencil. The curve created by repeating this process is the involute curve.
When two tooth profiles made in this way are meshed and rotated, the contact points of both tooth profiles move smoothly on the same curve. Because of these characteristics, the involute curve can be considered suitable for tooth profile curves.
Easy to manufacture and ensuring accuracy, involute splines are more versatile than conventional square splines. Since each spline type has its characteristics, selecting the appropriate type for each application is necessary.