| 摘要 |
A material hardness testing apparatus is provided, for use in quality control of production materials and parts, in which a pneumatically actuated indenter probe, incorporating an LVDT displacement transducer, is coupled by an analog-to-digital converter to a microprocessor-based computer that controls the cyclic actuation of the indentor probe, and processes indenter measurement data received from the LVDT transducer. The pneumatically actuated indenter probe includes pneumatic control means for providing independently adjustable control over the rates of probe impact and retraction in order to achieve consistent hardness measurements from cycle to cycle, together with relatively rapid displacement cycling of the indenter probe. The microprocessor-based computer incorporates a recalibration processor which automatically causes the testing apparatus to branch into a recalibration routine after a predetermined period of operation. During such recalibration, the apparatus semi-automatically tests and compares the measured hardness of one or more reference specimens with hardness values stored in memory and either disables the testing apparatus when the measured hardness deviates from the standard by a predetermined percentage amount, or stores in memory the difference between the measured hardness and the standard and enables the apparatus to continue with further testing. In each succeeding test, the apparatus automatically subtracts or adds the magnitude of the memorized difference to the raw measured hardness value to correct the hardness reading displayed by the apparatus.
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