| 摘要 |
[An output axis of a motor has an eccentric portion, a vibratory arm is vibratably supported at its central portion, connecting section of said vibratory arm with the eccentric portion is formed in shape of two crotches, the eccentric portion and the vibratory arm are connected to each other in a manner that the eccentric portion is inserted between the two crotches of the vibratory arm, thereby rotational movement of the output axis of the motor is converted into vibrational movement of the vibratory arm, and at least one of contact portion formed on the outer circumfrential surface of the eccentric portion or contact portions respectively formed on the inside surface of each of two crotches is formed in shape of a curved surface.]A power tool has a drive section with a shaft having a rotational axis and an eccentric portion offset from the rotational axis. An arm drivingly connects the shaft to a tool working member. The arm has one end formed in the shape of a fork with a pair of prongs, and is pivotable about a vibrating axis generally perpendicular to the rotational axis. A first contact portion on the eccentric portion engages a second contact portion on the prongs to convert rotational movement of the shaft about the rotational axis into pivotal movement of the arm about the vibrating axis to pivot the working member about the vibrating axis. At least one of the first and second contact portions has a curved surface of which a contour curves on a plane generally perpendicular to the vibrating axis.
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