Abstract: A method for manufacturing a gear which effectively prevent a crack from occurring inside a tooth part when rolling processing is performed on a teeth part of a gear raw material is achieved. A method according to one embodiment for manufacturing a gear by performing rolling processing on a tooth part of a sintered gear raw material. The method includes, when the rolling processing is performed on the tooth part of the gear raw material, pressing the gear raw material toward a center of rotation of the gear raw material by a rolling machine and, when at least the rolling processing is performed on the tooth part of the gear raw material toward a center of a thickness thereof by a pressing machine, pressing a region where an internal density of the tooth part of the gear raw material decreases.

Abstract: Provided is a method for producing a fuel cell that can reduce the amount of an adhesive applied to join a pair of sheet-like separators together while also avoiding failures in the conveyance of the separators. A separator, which has a bent portion on the peripheral edge thereof and has a recess and a projection formed on one surface and the other surface, respectively, of the separator by the bent portion, is used. The conveying step includes gripping the bent portion at opposite ends of each separator using grippers. The seal portion forming step includes disposing an adhesive in the recess formed by the bent portion of one of the separators, and fitting the projection formed by the bent portion of the other separator in the recess.

Abstract: A method for manufacturing a gear which effectively prevent a crack from occurring inside a tooth part when rolling processing is performed on a teeth part of a gear raw material is achieved. A method according to one embodiment for manufacturing a gear by performing rolling processing on a tooth part of a sintered gear raw material. The method includes, when the rolling processing is performed on the tooth part of the gear raw material, pressing the gear raw material toward a center of rotation of the gear raw material by a rolling machine and, when at least the rolling processing is performed on the tooth part of the gear raw material toward a center of a thickness thereof by a pressing machine, pressing a region where an internal density of the tooth part of the gear raw material decreases.

Abstract: Provided is a method for producing a fuel cell that can reduce the amount of an adhesive applied to join a pair of sheet-like separators together while also avoiding failures in the conveyance of the separators. A separator, which has a bent portion on the peripheral edge thereof and has a recess and a projection formed on one surface and the other surface, respectively, of the separator by the bent portion, is used. The conveying step includes gripping the bent portion at opposite ends of each separator using grippers. The seal portion forming step includes disposing an adhesive in the recess formed by the bent portion of one of the separators, and fitting the projection formed by the bent portion of the other separator in the recess.