7
Ultrasonic method
The principle of operation of ultrasonic probes of the hardness tester is based on the
method of measuring ultrasonic contact impedance (UCI - ultrasonic contact impedance).
At the end of the metal rod, which is part of the hardness tester probe, a diamond tip is
fixed. The rod oscillates at its own resonant frequency. When a load is created by the user's
hand, the diamond tip is embedded in the material and changes the resonant frequency of the
rod. The change in the natural resonant frequency of the rod is proportional to the depth of
penetration of the tip into the material. Since the penetration depth of the tip into the material
is an indicator of hardness, there is a relationship between the change in the resonant
frequency of rod F and the hardness of the material H: H = f ( F ).
1.3 Hardness tester functions
The control is carried out:
− according to the main scales: Rockwell (HRC), Brinell (HB), Vickers (HV), and
Shore for measuring the hardness of carbon structural steels;
− scale conversion: Rockwell (HRA), Rockwell (HRB), to control the hardness of
carbon structural steels;
− on additional scales set in the hardness tester by the manufacturer for hardness
control or scales created by the user:
− alloy, tool steels,
− aluminum alloys in Brinell units (НВ),
− brass (copper-zinc alloys) in Brinell units (НВ),
− bronzes (copper-tin, copper-aluminum) in Brinell units (НВ);
− using custom scales of hardness tester - for cases when the physical and
mechanical properties of the controlled material differ from carbon structural
steels (high-alloy steels, specialized cast irons, non-ferrous metals, alloys, etc.).
It is possible to calibrate the main scales in the event of an additional error after
prolonged use.
The hardness tester is equipped with a bright color display and a strong case for
To Next Page
Loading...
Need help?
General