Fastening device for air cylinder

A fastening device for an air cylinder, the fastening device comprising:

• a belt including a first end portion and a second end portion;
• a coupling ring attached to the first end portion of the belt;
• and
• a buckle to which the second end portion of the belt is attached,
• the buckle including a front face and a rear face, a distal end edge, base end edges, base end portions, and locking grooves that are disposed in the base end portions and in which locking portions of the coupling ring are releasably locked,
• the locking grooves including openings that gradually widen toward a rear face side,
• the front face of the buckle including bent portions that are brought into contact with an outer circumferential face of the air cylinder when coupling between the belt and the coupling ring is released,
• wherein
• an inner circumferential face of the locking groove includes an inclined wall face disposed on a distal end side of the buckle, a first wall face extending from the inclined wall face toward a front face side, and a second wall face disposed on a base end side and a bottom wall connecting the first wall face and the second wall face,
• a corner is disposed between the inclined wall face and the first wall face, and
• a spacing dimension between the bottom wall and the corner is larger than a radius of the locking portion.