| 摘要 |
In the case that an electric screw tightening machine has a configuration in which a speed change to a low-speed high-torque output state is automatically achieved in conjunction with increase in an external torque of a spindle, this output state is locked by a speed change lock mechanism, and this lock state is reset by an OFF operation of a switch lever, and that the tightening machine is configured such that the speed changing device is switched from a high-speed low-torque output state in which the second stage internal gear rotates together with a first stage carrier to a low-speed high-torque output state caused as the second stage internal gear is disconnected from the first stage carrier so as to be restricted from rotating, an impact produced at the time of engagement between the first stage carrier and the second stage internal gear at the time of resetting is reduced to improve the durability of the speed changing device. Timing of resetting the speed changing device is shifted relative to timing of stopping the electric motor by an OFF operation of the switch lever by a delay mechanism (D1), so that the second stage internal gear (34) is engaged with the first stage carrier (23) after the rotation through inertia is stopped, whereby its impact is reduced. |
