In many
practical situations, you may have come across washers that were not totally
flat, but curved in nature. These curved washers are called Belleville spring
washers.
As you
can see from the picture above, a Belleville spring washer is curved in cross
section. Apart from that' everything is similar to an ordinary washer. It has a
centre hole, through which bolt is inserted for assembling it.
A
Belleville spring washer is placed at one end of a bolted joint in place of
ordinary washer. Specific torque (depends upon the Belleville spring washer
design) should be applied for tightening the nut. After the tightening is done,
the spring action of the Belleville spring washer protects the joint from
loosening even in a rough environment.
If a
bolted joint requires multiple Belleville spring washers to be used at a place
then the washers can be assembled in two possible ways:
1.
Butting the concave surface of the top washer to the convex surface of the
bottom washer.
2.
Butting the convex surface of the top washer to the convex surface of the
bottom washer or vice versa.
The first
case is called “Parallel" stacking and the second case is
called “Series" stacking.
○ Belleville spring
washer offers continuous clamping pressure to the bolted joint, as a result the
bolted joint does not become loose while operating in
a vibration prone environment.
○ As compared to a
helical spring washer, it takes less space for installation.
○ Belleville spring
washers can be assembled in parallel to increase the load-withstanding capacity
of the joint.
○ Similarly,
deflection of the joint can be increased by assembling multiple washer in
series.
Curved
cross section of Belleville spring washer produce spring action in
the bolted joint. To get the full benefit of a Belleville spring washer,
check out the Belleville spring washer design load and apply tightening torque
accordingly.