Abstract: There is provided a relief valve capable of realizing miniaturization, weight reduction, and simplification of structure, and preventing vibration during operation. A relief valve for releasing a pressure by causing a valve body to separate from a valve seat when a pressure exceeding a set value is applied to the valve body, including an urging member that applies an urging force to the valve body to press-contact the valve body with the valve seat, the urging member being locked to a force receiving section fixedly formed in a middle portion in the axial direction of the valve body either integrally with or separately from the valve body and directly applies the urging force to the force receiving section.

Abstract: In the double-side polishing apparatus, one end part of a slurry supply hole has a female-tapered face whose inner diameter is gradually increased toward a polishing face of a polishing plate. A pad hole, which corresponds to the slurry supply hole, is formed in a polishing pad covering the slurry supply hole. An edge of the pad hole is located in the slurry supply hole. A fixation pipe, in which a flange section facing the female-tapered face is formed at one end part, is fixed in the slurry supply hole. The edge of the pad hole is sandwiched and held between the female-tapered face of the slurry supply hole and the flange section of the fixation pipe.

Abstract: In the double-side polishing apparatus, one end part of a slurry supply hole has a female-tapered face whose inner diameter is gradually increased toward a polishing face of a polishing plate. A pad hole, which corresponds to the slurry supply hole, is formed in a polishing pad covering the slurry supply hole. An edge of the pad hole is located in the slurry supply hole. A fixation pipe, in which a flange section facing the female-tapered face is formed at one end part, is fixed in the slurry supply hole. The edge of the pad hole is sandwiched and held between the female-tapered face of the slurry supply hole and the flange section of the fixation pipe.