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Page 13
Fig. 6.3.2 (Raw data graph)
7.
ROLLER SHAFT BENDING:
7.1
Measurement Principle
On a kiln support roller, the variation of the deflection of the roller shafts show possible cranks.
Cranks are straightness errors in the kiln shell, which are affecting the loads on the roller stations
with each kiln revolution.
There are two types of cranks:
•
Permanent / Mechanical Crank:
Caused by plastic deformations in the kiln shell or errors during the kiln construction.
•
Thermal Crank:
Caused by uneven temperature distribution / thermal expansion around the kiln shell
circumference. (most severe close to the middle tire)
The load changes caused by cranks can be very strong and overload the tires and rollers, which
results in cracks in tires, rollers and roller shafts.
The crank pushes the roller down; hence the distance between the sensor and the roller surface is
reduced. Half a kiln revolution later, the crank turns up and the load gets reduced on this station;
hence the distance to the sensor is getting bigger.
7.2
Place the Sensor
To measure the effect of a crank, an inductive sensor, typically Ø12mm is placed under the support
roller in the line of force. That means on the opposite side of the contact to the kiln tire.
(See pictures below)
Due to the high stiffness of the roller shafts, these movements are very small (within tenths of
millimeter), therefore it is recommended to use the smallest sensor of the IDM Tool Kit (Ø12mm) to
have the highest accuracy
Stop Button (F6)
to generate time staps
Click mouse right to
change the X and Y axis
Set Mark (F9)
April 4, 2022
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