On the Measuring Apparatus of the Eccentricity in Corered Welding Electrode and its First Tentative Model

There has recently been developed in America an electronic instrument for measuring the eccentricity of the core wire of covered arc-welding electrodes, but in Japan we have yet no such development, mechanical measurement by means of a micrometer being a general practice. We have made it possible to measure the eccentricity electrically by the application of the magnetic field. Our instrument has the important advantages that the readings can be obtained directly or by a dial indicator and its accuracy is not affected by the thickness of the welding electrode. The covered electrode is introduced into the magnetic field of an L- type coil, where inductance varies by rotating and translating the electrode, and induces the change of voltage or current in the circuit. Thus, if the proper indicator, for example, microammeter is arranged through zero-method, it indicates the eccentricity of the electrode under test. The sensibility is 9/1000mm/0.5μA, the errors being less than a few percentages.