| 摘要 |
An electric bolt/nut fastener is provided to prevent an error of judging the abrupt drop of the current value immediately after the abrupt rise of the current value during start of a motor as a shearing of a shear washer. An electric bolt/nut fastener includes an inner socket to be fastened with a chip of a front end of a bolt; an outer socket engaged with a nut bolt-jointed to the bolt; a motor(15) for connected to the sockets through a decelerator for providing rotating force in the direction for oppositely rotating the sockets; and a control unit(44) for controlling rotation of the motor. The control unit includes a first rise detection unit(44a) for detecting a abruptly rising start current of a current value of the motor when a start switch is turned on; and a first fall detection unit(44b) for detecting abrupt fall and convergence of the current value immediately after detection of the abrupt rise of the current value performed by the first rise detection unit. The control unit judges that the rising of the start current is ended when the first fall detection unit detects abrupt drop and convergence of the current value, and detects abrupt rise of the current value when the start switch is turned on from the rise of the current value during fastening of a bolt/nut to be executed later.
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