Toyota Jidosha Kabushiki Kaisha

Norihisa Hirao

Kazunari Kirii

Munetaka Toda

A balancing apparatus for a pressing machine, including a force generating device for generating a force during a pressing operation on a blank, and a plurality of balancing hydraulic cylinders which have respective oil chambers communicating with each other and which include respective pistons that are moved to neutral positions thereof during the pressing operation, for evenly distributing said force, and where a discharge control device is connected to a connecting passage connecting the oil chambers of the balancing hydraulic cylinders to each other, so that the discharge control device inhibits a discharge flow of a working fluid from the hydraulic cylinders and thereby holding the pistons of all of the hydraulic cylinders at upper stroke ends thereof, prior to the pressing operation, and permits the discharge flow of the working fluid to thereby permit the pistons to be moved to the neutral positions during the pressing operation.

Apparatus including mutually communicating hydraulic cylinders for even

A press wherein a blank-holding force generated by cushioning cylinders is transmitted to a pressure member through cushion pins for holding a blank during a pressing operation by a die and a punch, and is controllable by a pressure adjusting device according to an optimum pattern of control by controlling a difference between fluid pressures in two pressure chambers of each cushioning cylinder whose volumes decrease and increase, respectively, as the cushion pins are lowered.

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Okazaki, Japan

Norihisa Hirao