| 摘要 |
PROBLEM TO BE SOLVED: To provide a rotary impact tool capable of preventing occurrence of excessive impact force by reducing driving force of a motor when fastening a screw, and generating the impact without reducing the impact force in the middle of rotation prior to screw fastening such as female screw forming by a drill screw.SOLUTION: In a rotary impact tool including an impact mechanism comprising a hammer, an anvil and the like, when the signal level of a detection signal Vs from an impact detection unit exceeds an upper limit (S330-YES), generation of an impact by the hammer is determined, and the number of impacts Ci is counted (S340). When the number of impacts Ci exceeds the number of seating determination Cth (S380-YES), the head of a screw is determined to have abutted (seated) on an object, to set a seated flag Fi (S390). Meanwhile, the seated flag Fi is used for reducing driving force of a motor (consequently the rotation speed) by reducing driving duty ratio of the motor driving the impact mechanism. |
