The spline connection consists of an inner spline and an outer spline. Both the inner and outer splines are multi toothed parts, with the splines on the inner cylinder surface being the inner splines and the splines on the outer cylinder surface being the outer splines. Obviously, spline connections are the numerical development of parallel key connections.

1. Classification of Splines

The types of commonly used spline shafts on the market can be roughly divided into three types: one is the rectangular spline shaft, which is widely used in machinery such as machine tools, automobiles, airplanes, etc; Another type is the involute spline shaft, which is mainly used for links with high centering accuracy requirements, large loads, and large dimensions; The third type is triangular splines, used for connecting thin-walled parts.

2. The usage characteristics of splines

Usage characteristics: Due to differences in structural form and manufacturing process, compared with flat key connections, spline connections have the following characteristics in terms of strength, process, and use:

Because more teeth and grooves are directly and uniformly produced on the shaft and hub hole, the coupling force is relatively uniform;

Due to the shallow groove, the stress concentration at the tooth root is relatively small, and the strength of the shaft and hub is weakened less;

With a larger number of teeth and a larger total contact area, it can withstand larger loads;

The alignment between the components on the shaft and the shaft is good, which is important for high-speed and precision machines;

Good guidance is important for dynamic connections;

Grinding methods can be used to improve machining accuracy and connection quality;

The manufacturing process is complex and sometimes requires specialized equipment, resulting in higher costs.

Applicable occasions: Connections that require high centering accuracy, transmit large torque, or frequently slip.

Most of the spline shafts seen on the market are made of 40Cr material, with a surface hardness requirement of HRC45-50 and requiring heat treatment.

3. Ball spline

Ball splines use balls installed inside the outer cylinder of the spline shaft to smooth the transmission torque of the rolling machine in a precision ground rolling groove. With a unique contact point design, they have a larger contact angle (40 °), which not only has high sensitivity but also greatly improves their ability to handle. They are suitable for environments with excessive vibration and impact loads, high positioning accuracy requirements, and the need for high-speed sports performance, It can also play an effective role in such environments. At the same time, even when used instead of linear ball bearings, the rated load of the ball spline is more than ten times that of the linear rail bearing due to the same shaft diameter, making the world very compact. Even under the action of cantilever load, torque, etc., it can be safely used and has high durability.

Elaborate on the advantages of ball splines

High load capacity: The rolling groove of the ball is precisely ground and formed, and adopts Goethe type 40 ° angle contact. Due to the large contact angle, it has a large load capacity in both radial and torque directions.

Zero clearance in rotation direction: By using 2-4 rows of relative ball bearings with a contact angle of 40 °, the spline is combined with the outer cylinder of the spline, and the pre pressing method can be adjusted to make the clearance in the rotation direction zero.

High sensitivity: Due to the special design of the steel ball contact point, in addition to high rigidity, it is more sensitive and can reduce capacity waste.

High rigidity: Due to the large contact angle, it has high rigidity and can achieve high torque rigidity and torque rigidity by applying appropriate preloading depending on the situation.

Easy assembly: Due to the special design, the outer cylinder of the spline is promptly detached from the spline shaft, and the steel balls will not fall off. Therefore, assembly, maintenance, and inspection are all easy to carry out.

4. The processing method of spline shaft

The spline shaft has a longitudinal keyway on the outer surface of the shaft, and the rotating parts on the shaft also have corresponding keyways to maintain synchronous rotation with the shaft. While rotating, some can also perform longitudinal sliding on the shaft, such as shifting gears in the gearbox. There are many processing methods for spline shafts, mainly using cutting methods such as rolling, milling, and grinding, as well as plastic deformation processing methods such as cold stamping and cold rolling.

Rolling cutting method: Use a spline hob to machine on a spline shaft milling machine or gear hobbing machine according to the generating method.

Milling method: On a universal milling machine, use a specialized forming milling cutter to directly mill out the contour between teeth, and use a indexing head to divide the teeth and mill them one by one; If a forming milling cutter is not used, two disc milling cutters can also be used to mill both sides of a tooth at the same time. After milling each tooth, a disc milling cutter can be used to slightly adjust the bottom diameter.

Grinding method: Use a formed grinding wheel to grind the side and bottom diameter of the spline teeth on a spline shaft grinder.