RELATED APPLICATIONS

The present application is National Phase of International Application No. PCT/JP2019/019250 filed May 15, 2019, and claims priority from Japanese Application No. 2018-231252, filed Dec. 11, 2018, the disclosure of which is hereby incorporated by reference herein in its entirety.

TECHNICAL FIELD

The present invention relates to a fastening device that fastens a bolt to a fastening target object.

BACKGROUND ART

A bolt/nut fastener is used to assemble and fix a large number of mechanical structures including an automobile as a representative example. Patent Literature 1 discloses a bolt having a male screw section formed around the outer circumferential surface of the bolt head section.

CITATION LIST

Patent Literature

Patent Literature 1: Japanese Patent No. 6,381,840

SUMMARY OF INVENTION

Technical Problem

An object of the present invention is to automate bolt fastening operation.

Solution to Problem

To achieve the object described above, the invention of the present application relates, as a viewpoint, to (1) a fastening device for fastening a bolt to a fastening target object, the bolt so configured that a bolt head section male screw section is formed around a side surface of a bolt head section and an engagement receiving section is formed at a top surface of the bolt head section, the fastening device including a tension rod including a rod female screw section that engages with the bolt head section male screw section, a bit that is so disposed inside the tension rod as to be movable in an upward/downward direction, includes an engagement section that engages with the engagement receiving section, and rotates the bolt around an axis extending in the upward/downward direction with the engagement receiving section engaging with the engagement section, a supporter that is disposed in a position where the supporter circumferentially surrounds the tension rod and has a lower end section protruding downward beyond a lower end section of the tension rod, a sensor for sensing compression force acting on the supporter in the upward/downward direction, a first motor for rotating the bit around the axis, and a second motor for rotating the tension rod around the axis.

(2) The fastening device described in item (1) above, in which a bolt shaft male screw section is formed around a shaft section of the bolt, and the rod female screw section and the bolt shaft male screw section have the same screw pitch.

(3) The fastening device described in item (1) or (2) above, in which a tubular holder is disposed inside the tension rod, and a magnet, the bit attracted by the magnet, and a spring that urges the magnet downward are disposed in the holder.

(4) The fastening device described in any one of (1) to (3) above, in which the engagement receiving section is an insertion hole, and the engagement section is a lower end section of the bit inserted into the insertion hole.

(5) The invention of the present application relates, as another viewpoint, to a fastening device for fastening a bolt to a fastening target object, the bolt so configured that a bolt head section female screw section is formed in an inner circumferential surface of a recess provided in an upper surface of a bolt head section, the fastening device including a tension rod including a rod male screw section that engages with the bolt head section female screw section, a drive socket that is disposed in a position where the drive socket circumferentially surrounds the tension rod and has a lower end section including a grasper for laterally grasping the bolt head section, a supporter that is disposed in a position where the supporter circumferentially surrounds the drive socket and has a lower end section protruding downward beyond a lower end section of the drive socket, a sensor for sensing compression force acting on the supporter in the upward/downward direction, a first motor for rotating the tension rod around an axis extending in the upward/downward direction, and a second motor for rotating the drive socket around the axis.

(6) The fastening device described in (5) above, in which a bolt shaft male screw section is formed around a shaft section of the bolt, and the rod male screw section and the bolt shaft male screw section have the same screw pitch.

(7) The fastening device described in (5) or (6) above, in which a projection is formed at a lower end section of the tension rod, and the rod male screw section is formed around an outer circumferential surface of the projection.

Advantageous Effects of Invention

The configuration of above-mentioned item (1) of the present invention allows automated tightening of a bolt so configured that a male screw section is formed around the outer circumferential surface of a bolt head section. The configuration of above-mentioned item (5) of the present invention allows automated tightening of a bolt so configured that a bolt head section female screw section is formed in the inner circumferential surface of a recess in the top surface of a bolt head section.

