There are three pendulum pendulums in the pendulum Hardness Tester: Koenig pendulum, Persaz pendulum and double pendulum.
(1) Koenig Pendulum
Koenig pendulum, see picture. It is supported by two separate steel ball bearings with a diameter of (5±0.005) mm, a steel ball spacing of (30 ± 0.2) mm, and a hardness of HRC (63 ± 3) or (1600 ± 32) HV30, and is used with the cross bar A sliding weight on a connected vertical rod is balanced and the natural frequency of oscillation can be adjusted by means of this weight. The oscillation period on a polished glass plate is (1.4 ± 0.02) s, and the damping time from a displacement of 6° to a displacement of 3° is (250 ± 10)s. The total mass of the pendulum is (200 ± 0.2) g.
(2) Persaz pendulum
Perthaz pendulum, see picture. It is supported by two separate stainless steel balls with a diameter of (8±0.005)mm, a steel ball spacing of (50 ± 1)mm, and a hardness of HRC (59 ± 1), without a balancer. The swing period on a polished glass plate is ( 100 ± 0.1 ) s, and the damping time from a displacement of 12° to a displacement of 4° is ( 430 ± 10) s. The total mass of the pendulum is ( 500 ± 0.1 ) g, its center of gravity at rest is ( 60 ± 0.1 ) mm below the fulcrum plane, and the tip of the pointer is ( 400 ± 0.2 ) mm below the fulcrum plane.
(3) double pendulum
Double pendulum, see picture. The total mass of the pendulum is ( 120 ± 1 ) g, and the length from the upper end to the lower end of the pendulum is ( 500 ± 1 ) mm. The two steel balls under the cross bar of the swing bar meet the specification requirements of 8C II in GB/T 308. The damping time of the pendulum swing angle from 5° to 2° on the unpainted glass plate is ( 440 ± 6 ) s.
The above are the characteristic parameters of the three different pendulum rods of the pendulum Hardness Tester.
