Vorrichtung zum Pressen,Druecken oder Tiefziehen duennwandiger Werkstuecke durch stossweise wirkenden hydraulischen Druck

1,105,257. Hydraulic apparatus. TOKYO SHARYO SEIZO KABUSHIKI KAISHA. Oct. 27, 1965 [Dec. 7, 1964; Jan. 14, 1965; March 2, 1965], No.45576/65. Heading F1P. [Also in Division B3] An apparatus for producing an impulsive hydraulic pressure in a liquid filled chamber 22 comprises a hammer 3 arranged to be propelled along a cylinder 1 by compressed air into direct contact with liquid in the chamber 22 or into striking engagement with the end of a plunger 21 having the other end thereof protruding into the chamber 22. The impulsive hydraulic pressure generated in the chamber 22 is utilized to expand a material 35 into the shape of a die 30 (see Division B3). To enable the forming operation to be accomplished in steps the chamber 22 may be supplied with additional liquid through a non-return valve connected to a pump. The hammer 3 is normally locked in its retracted position by a pin 5 urged by a spring 6 into engagement with a groove 4 in the hammer 3. To operate the hammer a valve 17 is opened manually, mechanically, or electromagnetically to allow compressed air supplied from an inlet 11 to each end of a spool valve 10 to escape from the lower end thereof. Hence the valve 10 moves down and air passes through an automatic cut-off valve 9 to cause the hammer to accelerate along the cylinder 1 and in the arrangement shown, strike the plunger 21. When the valve 17 is released compressed air from the inlet 11 passes through a restriction 18 to return the valve spool 10 to its original position. The hammer is then returned by compressed air from a tank 15 admitted to the cylinder 1 through a pipe 14. In the alternative arrangement, Figs. 3-7 (not shown) the hammer 3 is arranged to move vertically downwards into direct contact with liquid in a bowl-shaped container having a central bore in communication with the chamber 22.