This article from Abssac explains the advantages that helical beam shaft couplings offer over alternative technologies.
Helical beam flexible shaft couplings have a reputation for reliability and anti-backlash torque transmission, but some engineers are not aware of the additional advantages the product can offer for power transmission applications. When parameters such as torque and angular shaft misalignment are outside of the normal limits, the helical beam product can be very useful.
The advantages lie in the way the actual helical beam configuration, or 'flexure' as it is often termed, can be tailored. In affect, the flexure part of the shaft coupling can be tuned to suit individual application requirements.
For example, by varying the thickness of the flexure, the coupling can accommodate increasing amounts of torque and radial loads. A design engineer can specify the torsional stiffness and compression spring rates independent of other factors such as angular offset and parallelism acceptance. When the inside diameter of the flexure changes, so does the torque capacity, torsional stiffness and axial spring rates, without restricting the choice of bore sizes. When the number of coils is changed, the torque capacity remains unaffected, but all the other characteristics change. Then the option to use multiple-start coils, such a double- and triple-start coil configurations, can ultimately provide higher torsional stiffness. [In the example shown here, a steep helix angle is used to give a high torque capacity. The customer also specified a split end cap attachment design to suit the application requirements.]
An additional advantage is the fact that high-strength materials such as 17-4PH CRES steels can be used as well as 7075-T6 aluminium. Factors such as elasticity, fatigue resistance, corrosion resistance, mass, magnetic permeability and operating temperature are all affected by the material choice.
The performance and attachments available to the engineer are therefore endless but ultimately allow a bespoke shaft coupling to be supplied. However, the machine tools that manufacture the standard shaft couplings can be utilised for these bespoke designs, which ensures cost-efficiency.
So the next time you are reviewing your rotary power transmission designs, it might be worth considering the Abssac helical beam shaft coupling.