| 摘要 |
PURPOSE:To obtain a hardness high-reliability measured value by detecting the varying speed of the resonance frequency of an oscillation rod against which an indenter is pressed in its measurement object surface, and deciding on the reliability of the current hardness measured value from the value of the varying speed. CONSTITUTION:The deviation DELTAf of the resonance frequency f1 of the oscillation rod 2 from a reference frequency f2 increases gradually right after the diamond indenter 3 is pressed against the measurement object surface 5 and then enters a steady state. The frequency shift DELTAf in this steady state depends upon the hardness of a body 4 to be measure. In this measuring method, the varying speed of the resonance frequency f1 of the oscillation rod 2 within a specific time right after the indenter 3 is pressed against the measurement object surface is calculated and compared with a set value by an abnormality decision circuit 8. The abnormality decision circuit 8 evaluates the reliability of the current hardness measured value and indicates that the current hardness measured value is an abnormal value when said varying speed is larger than the set value. |
