The pendulum Hardness Tester needs to be calibrated regularly during the test to ensure the accuracy of the test results. The standard stipulates that the standard damping time of the Koenig pendulum from a displacement of 6° to a displacement of 3 ° is (250±10)s, and the swing period is (1.4 ± 0.02)s; The standard damping time is ( 430 ± 10 ) s; the standard damping time for the double pendulum from 5° displacement to 20 is ( 440 ± 6 ) s. If the damping time is not within the range specified by the standard, the instrument needs to be calibrated.
First adjust the level of the instrument, check the steel ball, and use a soft silk cloth to dip a suitable solvent (such as absolute ethanol) to wipe the supporting steel ball clean, then wipe the standard glass plate and test again. If the damping time is still not within the specified range, then the Persaz pendulum needs to be replaced, and the Koenig pendulum and double pendulum can also be calibrated by adjusting the weight.
( 1 ) Correction of konig pendulum
Among them: T-swing period;
m1 one point hem length total mass;
m2—the total mass of the pendulum length at the fulcrum;
L1 — length of the fulcrum hem ;
L2 — length of the fulcrum hem ;
g is the acceleration due to gravity.
It can be seen from the formula (1) that if the weight is moved up to increase L2, then T will increase. To increase the damping time, that is, to increase the swing period T, it is necessary to move the weight up a certain distance.
( 2 ) Correction of double pendulum
Among them: T-swing period;
L is the distance from a point to the weight ;
g is the acceleration due to gravity.
It can be seen from formula (2) that adjusting the damping time is to adjust the swing period T, and T changes with the change of distance L. When L increases, T increases, that is, the damping time increases. Therefore, to increase the damping time, it is necessary to move the weight down - a certain distance. However, it should be noted that the two weights on the pendulum should move at the same time during adjustment, so that the two weights are always at the same horizontal position.
