Abstract: A nut runner, an attachment unit, and a sliding member are provided in a second arm that is a leading arm of the robot and has a leading end shaft movable along the direction of an elevation axis. The nut runner includes a screw fastening driver, a drive shaft rotationally driven by the screw fastening driver, and an extension bar that is so connected to rotate together with the drive shaft in the circumferential direction and to move in the axial direction. The attachment unit fixedly connects the screw fastening driver to the second arm so that a screw fastening axis parallel to the elevation axis serves as a rotation axis of the screw fastening driver. The sliding member is connected to the leading end shaft and supports the extension bar so as to move together in the axial direction and are rotatable relatively in the circumferential direction.

Abstract: An object is to improve accuracy of tightening torque and to shorten time necessary for fastening a screw in an impact type screw fastening device that uses an electric motor as a rotation driving source. A control method for the impact type screw fastening device that uses an electric motor as a rotation driving source includes the steps of driving the motor to rotate by supplying current to the motor intermittently so that torque exerted on a load by rotation of the motor becomes like pulses on the time axis, and controlling the current of every time of each pulse so that an increment of every time of each pulse of the torque after the torque reaches a target approach torque TQN that is a first set value becomes smaller than that before it reaches the target approach torque TQN.

Abstract: An object is to improve accuracy of tightening torque and to shorten time necessary for fastening a screw in an impact type screw fastening device that uses an electric motor as a rotation driving source. A control method for the impact type screw fastening device that uses an electric motor as a rotation driving source includes the steps of driving the motor to rotate by supplying current to the motor intermittently so that torque exerted on a load by rotation of the motor becomes like pulses on the time axis, and controlling the current of every time of each pulse so that an increment of every time of each pulse of the torque after the torque reaches a target approach torque TQN that is a first set value becomes smaller than that before it reaches the target approach torque TQN.

Abstract: It is an object of the present invention to overcome various drawbacks of a conventional oil pulse wrench by using an electric motor, to reduce a reaction force and to fasten a screw with high precision. To achieve the object, the invention provides a control method of a screw fastening apparatus using an electric motor as a rotation driving source, the method comprising the steps of; intermittently supplying current pulse DP to the motor, detecting an actual torque at predetermined time intervals, maintaining a current value when a detected torque value does not exceed a maximum value of past detected torques value and increasing the current value by a predetermined amount when the detected torque value exceeds the maximum value of the past detected torque value, and stopping the supply of the current pulse DP when the detected torque value reaches a target value TQJ.

Abstract: It is an object of the present invention to overcome various drawbacks of a conventional oil pulse wrench by using an electric motor, to reduce a reaction force and to fasten a screw with high precision. To achieve the object, the invention provides a control method of a screw fastening apparatus using an electric motor as a rotation driving source, the method comprising the steps of; intermittently supplying current pulse DP to the motor, detecting an actual torque at predetermined time intervals, maintaining a current value when a detected torque value does not exceed a maximum value of past detected torques value and increasing the current value by a predetermined amount when the detected torque value exceeds the maximum value of the past detected torque value, and stopping the supply of the current pulse DP when the detected torque value reaches a target value TQJ.