Construction and working of Sigma comparator:
The Plunger will hold the contact with the work piece, and it is positioned in place with the help of slit diaphragms.
the plunger will have a notch at its centre as shown in the figure.
A knife Edge is attached to the plunger to magnify the linear movement of the plunger. which
is connected to the Cross strip with the help of moving the block.
The Y-shaped metallic arm is connected to the cross strip to Driving drum. This arm rotated and makes the drum to rotate and hence the pointer will move on the scale.
The first step of magnification take place at the knife edge and cross strip and the second step of magnification is done at the drum diameter and the pointer length.
Working :-
When the component which is to be inspected is kept below the plunger according to dimension w.r.t. the standard value the plunger will move upward or downward. as the plunger moves knife edge gives motion to the moving block. This motion of moving block w.r.t. fixed block and cross strip hinge , gives motion to the Y arm . As the end of Y arm moves it causes the phosper bronze wire to rotate the driving drum. Driving drum gives motion to the pointer , which shows reading on the scale. and according to the reading the size of component w.r.t. standard is compared.
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Engineering Meterology
