Joint structure

A joint structure comprising:

• an articulated robot arm having an opening having a first peripheral wall comprising a first main joint surface, and a shoulder surface traversing the opening comprising a first sub joint surface that three-dimensionally intersects with the first main joint surface;
• a cover for the robot arm, the cover having a second peripheral wall corresponding to the first peripheral wall, the second peripheral wall comprising a second main joint surface opposite to the first main joint surface, and an edge surface comprising a second sub joint surface opposite to the first sub joint surface;
• a guide configured to gradually shorten a distance between the first sub joint surface and the second sub joint surface that are opposite to each other as a distance between the first main joint surface and the second main joint surface that are opposite to each other decreases, the guide enabling joining of the second sub joint surface to the first sub joint surface in a state of surface contact, upon joining of the second main joint surface to the first main joint surface in a state of surface contact, the guide being further configured to position the cover relative to the robot arm;
• and
• a fastening member configured to fasten the first main joint surface and the second main joint surface, which have been joined to each other, to each other,
• wherein the guide causes the cover to move at least in a direction parallel to the first main joint surface;
• wherein the guide comprises a guide projection provided on one of the first main joint surface and the second main joint surface, and a guide hole formed in the other of the first main joint surface and the second main joint surface, and adapted to receive the guide projection fitted therein;
• and
• wherein the guide hole and guide projection each have an inclined guide surface angled toward a respective one of the first and second sub joint surfaces that causes the cover to move toward the first sub joint surface as the guide projection is inserted deeper into the guide hole.