Member linking mechanism

A member coupling mechanism comprising:

• a first member including a cylindrical member coupling portion having an opening at a tip end face thereof, the cylindrical member coupling portion including a stepped portion inclined along a circumferential direction from a tip end side of the cylindrical member coupling portion toward a base end side thereof;
• a second member configured to be coupled to the cylindrical member coupling portion;
• and
• a coupling member configured to be engaged with the stepped portion of the cylindrical member coupling portion while holding an end portion of the second member on a side of the first member,
• wherein the coupling member is provided with a cylindrical protrusion protruding toward an outer peripheral surface or an inner peripheral surface of the cylindrical member coupling portion, the cylindrical protrusion being configured to be engaged with the stepped portion of the cylindrical member coupling portion, the cylindrical protrusion having a central axis arranged in a protruding direction of the cylindrical protrusion and being rotatable on the central axis, and
• wherein when the coupling member is rotated in a circumferential direction of the cylindrical member coupling portion, the cylindrical protrusion moves along the stepped portion while rotating on the central axis to press the first member and the second member in an approaching direction to couple them.