A magic carpet fix from Abssac

Abssac’s customer had an application where a precision encoder was being connected to a carpet manufacturing machine output shaft.  The machines are used to manufacture man-made fibre twisted loop pile carpets for domestic use.

If the vibration and movement present at the output shaft was transmitted to the encoder, it would cause signal errors and ultimately prematurely destroy the encoder. Ultimately this would lead to below standard carpet being produced due to loom operational irregularities.

Whilst very little torque was required in the application, torsional stiffness and zero backlash were important design parameters. The customer also wanted a low maintenance solution. 

From a coupling design aspect, the application required large axial motion and parallel misalignment because of the assembly tolerances of the crankshaft. The customer was originally using a multi- part bellows shaft coupling, but the required angular and axial movements lead to premature failure. Additionally, under certain operating conditions, the bellows coupling allowed too much vibration to reach the encoder. 

The solution was found using an adapted Heli-Cal flexible beam shaft coupling. A low inertia Aluminium part was created using two flexible beam elements in the single piece design.

Two integral clamps held the shafts, each flexible element allowed for the maximum angular and axial offsets set by the customer but maintained a high degree of torsional stiffness.  A "no charge" sample was then sent for test and evaluation.

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