Hydraulic fine blanking head for a press and method of its infeed

A hydraulic fine blanking head for a mechanical press that is supported by a head piece mounted on a machine frame of the press at a position above a ram, the ram supporting a table top, the ram executing a stroke movement on stroke axis, the hydraulic fine blanking head adapted for retention in the head piece and comprising

• a flange having a tube-shaped portion, the flange further having a shoulder fixed to a head piece frame on a ram-facing side of the head piece frame;
• a main cylinder positioned within the tube-shaped portion of the flange;
• a pair of pistons and piston pins positioned within the main cylinder;
• the main cylinder having pressure tight seals provided by an upper main cylinder cover and a lower main cylinder retaining plate;
• an adjusting mechanism including a cylindrical adjusting nut retained within a frame of the head piece, the cylindrical adjusting nut having an internal motion thread positioned on an interior of the cylindrical adjusting nut, the cylindrical adjusting nut being turnable around the stroke axis, a first sprocket wheel positioned on the stroke axis and being fixed to rotate at a frontal surface of the adjusting nut;
• a hydraulic motor provided with a motor shaft that is located at the head piece, a driving chain in connection with the motor shaft and the first sprocket wheel;
• a brake, positioned at a motor shaft braking position;
• an external motion thread provided on the exterior of a head portion of the main cylinder, the external motion thread of the head portion of the main cylinder being engaged with the internal motion thread positioned on the interior of the cylindrical adjusting nut;
• a conduit extending into the head piece and connected at an exterior end with a source of pressurized hydraulic fluid, the conduit delivering a flow of pressurized hydraulic fluid to a head piece position;
• whereby, when the flow of the pressurized hydraulic fluid attains a locking pressure in the head piece, the external motion thread of the head portion of the main cylinder and the internal motion thread positioned on the interior of the cylindrical adjusting nut enter a locked thread position that prohibits an axial backlash of the main cylinder, and
• when the flow of the pressurized hydraulic fluid is shut off, the external motion thread of the head portion of the main cylinder and the internal motion thread positioned on the interior of the cylindrical adjusting nut disengage from the locked thread position and enter into an unlocked position freeing the main cylinder to move through axial backlash;
• and wherein, infeed of the main cylinder with regard to the ram is adjustable by operation of the motor and the brake between on and off positions.