IMPACT HARDNESS TESTING METHOD AND IMPACT HARDNESS TESTING DEVICE APPLIED TO THEREFOR

摘要

PURPOSE:To find proper impact hardness by processing the electromotive force of a pickup coil placed in a magnetic field and calculating indenter speeds right before collision and right after repulsion. CONSTITUTION:The coil 6 for magnetic field production is arranged around a measurement cylinder 1 and supplied with electric power from a power source 7 to produce a constant magnetic field in the space in the measurement cylinder 1. Its electromotive force is shaped by a processing circuit to obtain a voltage with a waveform (b) and frequency-divided to obtain a voltage with a waveform (c). The clock (d) of 10MHz is gated with the waveform (c) to obtain pulses proportional to the time T1 that an indenter 2 requires to pass between two pickupo coils 5 and a passing time T2 after repulsion. Those pulses are counted by two universal counters to display the times T1 and T2. The repulsion coefficient K of the identer 2 to a sample 4 is expressed as the ratio of the times T1 and T2 and the speeds of a ball before and after collision are found from the distance between the two pickup coils 5 and the times T1 and T2.