PURPOSE: To remarkably simplify a hydraulic circuit with only two conduits of pressure side and nonpressure side by obtaining pressurizing operation of a main piston through pressurizing force which is obtained by multiplying pressure of pressure medium from a pressurizing conduit and an area that is obtained through reduction of an area of a returning chamber of a stepped surface from an area of the pressurizing chamber.
CONSTITUTION: When pressure medium is flowed into a pressurizing chamber 8, a main piston 2 reciprocates and a forging tool 5 proceeds. It is thus possible to make the forging tool 5 proceed and follow-up a driving rate of a pilot piston 3 by means of a driving mechanism 4 and perform forging process on a forged material. Pressurizing force as unbalanced force is generated on a main piston 2, which force is prepared by multiplying pressure of the pressure medium from a pressurizing conduit 6 and an area obtained through reduction of an area of a returning chamber 9 of a stepped surface 2j from an area of a pressurizing chamber 8, that is, a sectional area of a small diameter cylinder 1b of a diameter D of the main piston 2. Small force due to the driving mechanism 4 is input, for generating a large load.
SATO SHUJI
SUZUKI TAKASHI
NODA TAKEHIRO
