15-06-2012, 05:26 PM
FLANGE COUPLING
Introduction of flange coupling.docx (Size: 252.75 KB / Downloads: 98)
Introduction to Flange Coupling
A flange coupling is a rigid assembly used to connect rotating shafts. The shape and configuration of the flange coupling may vary but the principle remains the same.
Flange couplings transmit power and torque in one of two ways.
1. Mechanically, with the use of spigots, dowel pins, special toothed systems, or fitted bolts loaded in shear.
2. Friction, due to the pressure between the mating surfaces of the flanges. The pressure is generated by the clamping force provided by bolts.
Flange couplings are used throughout industry. Typical applications include coupling shafts in power transmission systems, gearboxes and automotive drive trains.
Friction drive couplings are less costly to produce, and when correctly specified provide an extremely reliable assembly. They are therefore the most common form of coupling used. The load capacity of such conventional flange couplings is a function of the clamping force, friction between the parts and the flange dimensions.
Traditional Coupling Design
For an unbonded bolted flange coupling the static torque capacity before slippage occurs is proportional to:
• The number of bolts
• The clamping force provided by each bolt
• The coefficient of friction between the two mating surfaces
• The dimensions and stiffness of the flanges
Failure for this type of coupling occurs when relative rotational slip occurs between the two flanges. Couplings are normally manufactured so that the bolts are a clearance fit in the holes to ensure they are not loaded in shear (unless rotational slip occurs).
Checking the coupling balance
Couplings are normally balanced at the factory prior to being shipped, but they occasionally go out of balance in operation. Balancing can be difficult and expensive, and is normally done only when operating tolerances are such that the effort and the expense are justified. The amount of coupling unbalance that can be tolerated by any system is dictated by the characteristics of the specific connected machines and can be determined by detailed analysis or experience.