Screw fastening system and screw fastening device

A screw fastening system comprising:

• a SCARA robot having a first arm at a base and a second arm on a leading end side of the first arm that is connected in series to the first arm wherein the first arm is configured to swing around a first axis that is located on a proximal end side of the first arm, and the second arm is configured to swing around a second axis that is located on the leading end side of the first arm, the first and second axes extending in parallel;
• a leading end shaft that is provided in a leading end side of the second arm, is driven to move up and down along an elevation axis that is an output shaft of the second arm by a driving means of the second arm, and extends in parallel to the first and second axes;
• and
• a screw fastening device that is fixed to a casing of the second arm in a screw fastening axis that is different from the elevation axis and parallel to the elevation axis such that the screw fastening device is configured to swing around the second axis together with the leading end shaft when the second arm swings around the second axis;
• wherein
• the screw fastening device includes
• a screw fastening driving means that is fixed to in the casing of the second arm,
• a drive shaft that extends from the screw fastening driving means in the screw fastening axis and is rotationally driven around the screw fastening axis by the screw fastening driving means,
• an extension bar that is connected to the drive shaft to rotate together in the circumferential direction of the screw fastening axis, is configured to move up and down along an axial direction of the screw fastening axis while keeping connected to the drive shaft, and is provided with a tool at a tip of the extension bar, and
• a sliding member that is fixed to the leading end shaft to move up and down in response to an up-down movement of the leading end shaft, and supports the extension bar in a manner of allowing the extension bar rotatable relatively in the circumferential direction of the screw fastening axis wherein the extension bar moves up and down following the sliding member,
• the up-down movement of the leading end shaft causes movement drive of the extension bar in the screw fastening axis through the sliding member, and a screw of a workpiece fitted to the tool is rotated by rotation drive of the extension bar, which is derived from the screw fastening driving means through the drive shaft.