Monday, July 18, 2016

What are bellows couplings?

A bellows coupling is a type of coupling design which consists of a thin walled, flexible corrugation (bellows) that is connected between two clamping hubs.  They are traditionally used for servo motion control applications that have high positioning accuracy, speed, and torque requirements.

Cross Section View of Bellows Coupling

What makes bellows couplings unique?
Bellows couplings are unique because of the construction of the bellows which can flex and compensate for minor shaft misalignments (axial, lateral, radial), while still providing a zero backlash and torsionally rigid connection.  They are a unique blend of rigidity and flexibility.

How to specify bellows couplings
To specify a bellows coupling, the first parameters we typically look at are the torque and connecting shaft sizes which will help to give a general sense of the coupling size.  The nominal torque rating (continuous torque transmission)  of the coupling should be greater than the peak torque of the application to ensure a secure connection.  We then check the connecting shaft sizes which  must also be within the acceptable range of the coupling.  If the shaft diameter is smaller than the specified range on the coupling, the torque transmission value of the coupling can decrease.  From there, we check other application specific parameters which include the speed, shaft alignment, temperature, and drive resonance.  We need to make sure they are within the coupling specifications, if not, we look to apply a safety factor when applicable; otherwise we select a different coupling size, or design. 

Bellows couplings applications examples
When introduced, bellows couplings were first widely accepted in the Machine Tool industry for spindle drives.  Since then usage has expanded to a vast number of industries including Automotive, General Automation & Assembly, Material Handling, Medical, Packaging, Robotics, to name a few.

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