Hydraulic forming machine for pressing workpieces, in particular forging hammer, and method for operating a hydraulic forming machine, in particular a forging hammer

A hydraulic forming machine, in particular a forging hammer, for workpiece forming, comprising:

• a hydraulic cylinder for driving a ram configured for workpiece forming, and a hydraulic circuit configured for operation of the hydraulic cylinder, wherein the hydraulic circuit has a valve with an adjustably variable volume flow, via which valve a first hydraulic working chamber of the hydraulic cylinder, used to accelerate the ram during the execution of a working stroke (A) for workpiece forming, can be provided with hydraulic fluid,
• wherein:
• the hydraulic circuit is configured to adjust and vary the volume flow of the valve depending on a setpoint speed (Vsoll) of the ram to be achieved in an acceleration phase of a working stroke (A), and
• the hydraulic circuit comprises a suction valve connecting the first hydraulic working chamber to a reservoir for hydraulic fluid, which suction valve is configured to fill the first hydraulic working chamber with hydraulic fluid from the reservoir in a movement phase which follows the acceleration phase and in which the setpoint speed (Vsoll) is substantially maintained.

A hydraulic forming machine, in particular forging hammer, for workpiece forming, comprising:

• a hydraulic cylinder for driving a ram configured for workpiece forming, which ram is mechanically coupled to the hydraulic cylinder, and a hydraulic circuit configured to operate the hydraulic cylinder and having an actuator for setting a volume flow of hydraulic fluid for filling a first hydraulic working chamber of the hydraulic cylinder during the execution of a working stroke (A) immediately preceding the workpiece forming, with an acceleration phase for accelerating the ram to a setpoint speed (Vsoll), and a movement phase which follows the acceleration phase and in which the setpoint speed (Vsoll) is substantially maintained,
• wherein the hydraulic circuit and the actuator are configured to:
• adjust and vary the volume flow in the acceleration phase as a function of the setpoint speed (Vsoll) such that the setpoint speed (Vsoll) is reached, and
• reduce the volume flow in the subsequent movement phase to a post-flow volume flow, in such a way that the hydraulic pressure prevailing in the movement phase in the first hydraulic working chamber is substantially above the cavitation pressure of the hydraulic fluid.

A method for operating a hydraulic forming machine for workpiece forming, wherein:

• in a working stroke (A) executed for the workpiece forming, a ram provided for the workpiece forming is accelerated in an acceleration phase by a hydraulic cylinder coupled to it,
• in the working stroke (A), a first hydraulic working chamber of the hydraulic cylinder is fed with hydraulic fluid via a valve with an adjustably variable volume flow through a hydraulic circuit,
• the hydraulic circuit, in the acceleration phase, adjusts and varies the volume flow of a valve as a function of a setpoint speed (Vsoll) of the ram to be achieved in the acceleration phase, and
• the first hydraulic working chamber, in a movement or braking phase which follows the acceleration phase and in which the setpoint speed (Vsoll) is substantially maintained, is filled by a suction valve which is present in the hydraulic circuit and which connects the first hydraulic working chamber to a reservoir for hydraulic fluid.

A method for operating a hydraulic forming machine for workpiece forming, wherein:

• in a working stroke (A) executed for the workpiece forming, a ram provided for the workpiece forming is accelerated in an acceleration phase by a hydraulic cylinder mechanically coupled to it,
• in the working stroke, a first hydraulic working chamber of the hydraulic cylinder is fed with hydraulic fluid via an actuator with an adjustably variable volume flow through a hydraulic circuit, and
• the hydraulic circuit:
• (i) in the acceleration phase, adjusts and varies the volume flow through the actuator as a function of the setpoint speed (Vsoll) in such a way that the setpoint speed (Vsoll) is reached, and
• (ii) in a movement phase which directly follows the acceleration phase and in which the setpoint speed (Vsoll) is substantially maintained, reduces the volume flow to a post-flow volume flow, in particular regulates it, such that the hydraulic pressure prevailing in the movement phase in the first hydraulic working chamber is substantially above the cavitation pressure of the hydraulic fluid.