Degradation Phenomenon of Electrical Contacts by Using a New Micro-Sliding Mechanism - The Comparison of a New Mechanism with the Former Concerning Minimal Sliding Amplitudes Evaluated under Some Conditions

Authors have developed a mechanism which gives damping vibration to electrical contacts by periodical hammering-oscillation and another mechanism which gives reciprocal micro-sliding to electrical contacts directly driven by a magnetostrictive actuator. It is shown that each mechanism is able to make a test simulate an actual degradation phenomenon on electrical contacts by the influence of micro-oscillation. By using the above mechanisms and their models they have studied the influences of micro-oscillation on contact resistance. In this paper, first, it is shown that there is degradation phenomenon of electrical contacts by experimental results using two reciprocal micro-sliding mechanisms (MSM1 and MSM2). MSM1 is the former mechanism and causes the sliding displacements between male-pins and female-parts by a magnetostrictive actuator & four parallel leaf springs. MSM2 is a new mechanism and causes the sliding displacements by a piezo-electric actuator & four elastic hinges. And it is also shown that the phenomenon depends on contact frictional forces between male-pins and female-parts and depends on sliding amplitudes and input waveforms directly driven by the actuators. Second, it is indicated that there are the minimal sliding amplitudes under which there is rarely degradation phenomenon and over which there is mostly degradation phenomenon in the following conditions. The conditions are two types of input waveform, two levels of frictional force and the number of pins. The waveforms are sinusoidal and rectangular. The initial frictional forces between male-pins and female-parts in an actual connector are normal (1.6 N/pin) and smaller (0.3 N/pin). And the numbers of pins are 10 (in a connector) and 1(in the case of a pair of male-pin and female-part) on MSM2 only. Consequently it is indicated that there are the minimal sliding amplitudes, correlating to input waveform and contact frictional force, which are estimated at ±1.0 μm (rectangular & smaller), ±3.3 μm (rectangular & normal), ±2.5 μm (sinusoidal & smaller), ±4.8 μm (sinusoidal & normal) if the amplitudes in the case of a set of male-pin and female-part by MSM2 are most valid.