| 摘要 |
<p>An electrical conduction mechanism which prevents dust or the like from adhering to the inside of an electrical-conduction portion main body, so that electrical conduction efficiency cannot be reduced. In one form the electrical conduction mechanism comprises an electrical-conduction portion main body in the center of which a first through-hole to be inserted through by a shaft is formed and in which a second through-hole communicating with the first through-hole is formed in a direction perpendicular to a direction in which the first through-hole is formed; and an electrical-conduction element disposed in the second through-hole. The electrical-conduction element is configured to include an electrical-conduction chip abutting on the shaft, and a coil spring biasing the electrical-conduction chip toward the shaft, so that current is supplied to the shaft through the electrical-conduction chip to conduct electricity to the bit.</p> |
