Custom-designed flexible beam coupling for encoder application

One of Abssac's customers recently had an application in which a precision encoder was being connected to the output shaft of a carpet manufacturing machine. This type of machine is used to manufacture man-made fibre twisted loop pile carpets for domestic use. The problem with this application was that if vibration and movement were transmitted from the output shaft to the encoder, it would cause signal errors and, ultimately, premature failure of the encoder. This would result in substandard carpet being produced due to loom operational irregularities.

While very little torque was required in this application, torsional stiffness and zero backlash were important design parameters. The customer also wanted a reliable, low-maintenance shaft coupling. From a coupling design aspect, the application required large axial motion and parallel misalignment due to the assembly tolerances of the crankshaft.

The customer was originally using a multi-part bellows shaft coupling, but the required angular and axial movements resulted in premature failure. Additionally, under certain operating conditions, the bellows coupling allowed too much vibration to reach the encoder.

Abssac solved this customer's problem by using an adapted Heli-Cal flexible beam shaft coupling. A low-inertia aluminium part was designed with two flexible beam elements in the single-piece coupling. Two integral clamps hold the shafts, with each flexible element allowing for the maximum angular and axial offsets set by the customer; importantly, this design still maintains a high degree of torsional stiffness. A 'no charge' sample was provided for test and evaluation.

Testing proved very successful and verified that the new helical coupling design provided better isolation of the encoder from the motor and better performance.

If you have a shaft coupling application for which standard couplings are not suitable, contact Abssac to find out how the company could solve the problem for you - or follow the link to read more about custom couplings.