Advantages Of Shrink Disks For Agitator And Mixer Drives

The drive systems for agitators and mixers are designed to offer high operational reliability and simplify assembly and maintenance. At least that's what users want. When designing the drive train, it must be taken into account that there can be considerable repercussions on the drive system if, for example, the agitator starts up against a highly viscous medium or the mixing tool against hard-flowing bulk materials.

This effect is often exacerbated by the fact that the agitator or mixing tool and drive are connected by a more or less long shaft, to which correspondingly high forces act. This applies in particular to the shaft-shaft or shaft-hub connections in the drive train. Here, among other things, high bending moments and high radial loads occur, for which conventional connecting elements are only suitable to a limited extent - and for several reasons. The classic positive key connection, which due to its design always has a certain amount of play, can wear out quickly under the typical alternating loads in such drives. Inner clamping sets are not a good alternative in this case because they are not suitable for high bending moments.

Secure and durable connection thanks to shrink discs

For this reason, many suppliers of mixers and agitators use a special type of frictional connection, which is known as the shrink disk. Since the shrink disks are installed outside the power flow, they are not subjected to dynamic forces when the drive is under high load. This increases the service life and the security of the connection.

In its simplest form, the connection system consists of an inner and an outer ring with opposite conical surfaces. Axial displacement (mechanical or hydraulic) of the outer ring against the inner ring creates a pressure. This compresses the inner ring inwards and presses the hollow shaft / hub onto the inner shaft. In contrast to thermally or otherwise joined frictional connections, Stüwe's frictional connections should be easy to install and, if necessary, can be dismantled without being destroyed. The clearance fits between the shaft or shaft hub and the shrink disk are intended to simplify assembly and maintenance. The shrink discs are insensitive to shocks and impacts, normal surface qualities can be used for shafts and hubs.

The series also includes stainless steel shrink discs. They are used in the drive trains of agitators and mixers that work in the pharmaceutical and food industries and are exposed to corrosive influences. (sh)