Hydropunch for use in a press

A hydropunch for use in a press including a die having a working surface for receiving a piece to be worked, comprising:

• a cylinder having a wall body with two ends, a first end facing the working surface of the die, and a second end facing in the opposite direction from said first end;
• a ram accommodated within said cylinder for movement therealong so as to form therein an above the-ram chamber and a below-the-ram chamber;
• means for actuating said ram, said means being arranged on the second end of said cylinder;
• a compressed gas receiver selectively communicable with the above-the-ram chamber of said cylinder, said means for actuating controlling fluid communication between said compressed gas receiver and said above-the-ram chamber in such manner that said ram is moved from an original raised position towards the first end of said cylinder when fluid communication is established;
• a cover for closing both said cylinder and receiver;
• and means for returning the ram to said original position, said means including a closed chamber communicating with the below-the-ram chamber of said cylinder, a valve adapted to communicate the above-the-ram chamber of said cylinder with the atmosphere, said valve being built in an opening provided in said cover, and a non-return valve for admitting used gas into said closed chamber, said non-return valve being built in a wall of said cylinder at a distance, from the one end thereof facing the die, approximately equal to the height of the ram so that said above-the-ram chamber is in fluid communication with said closed chamber through said non-return valve when said ram is in the lowest position thereof, and a high pressure chamber containing an elastic fluid positioned at the end of cylinder between the ram and the working surface of the die.