The invention relates to a hydraulic press and a method of pressing different kinds of objects, such as briquettes. The hydraulic press comprises a body cylinder (1) housing a fluid space (2) and a working piston (3) whose rod (3a) extends to the outside of the body cylinder (1), the working piston (3) being adapted to be moved in the fluid space (2) by hydraulic pressure. The hydraulic press also comprises a pressure accumulator (4) as well as a hydraulic circuit with valves. Inside the working piston (7) moved by hydraulic pressure, a striking piston (7) moving along with the working piston (3) and quickly movable relative to the working piston (3) by means of hydraulic pressure, is provided. In addition, a separate impact body (10) is provided between the striking piston (7) and the object (14) pressed by the hydraulic press.

An apparatus for the controlled return of the stems in cylinders of the types that can be applied to a press for stamping sheet metal, comprising: at least one fluid-operated cylinder), at least one hydraulic accumulator which is fluidically connected to the at least one cylinder by means of a hydraulic circuit which comprises: a duct for the discharge of the working fluid from the at least one cylinder and a duct/branch for the intake of the working fluid in the hydraulic accumulator, a duct for loading the working fluid in the at least one cylinder and at duct/branch for the output of the working fluid from the hydraulic accumulator.

A press system providing excellent energy efficiency for a whole press system and capable of achieving low prices is provided. A die cushion apparatus constituting a press system supports a cushion pad, includes a hydraulic cylinder which generates a die cushion load on the cushion pad when a slide of a press machine descends, the press machine includes a hydraulic cylinder which generates part of a press load on the slide when the slide descends. The pressure generation chamber of the hydraulic cylinder for generating a die cushion load and the pressure generation chamber of the hydraulic cylinder for generating part of the press load can communicate with each other via pipes and a first logic valve for a period during which the die cushion load acts.

A hydraulic press includes a workbench having four corners provided with uprights. The uprights are arranged in two rows front and rear, and the tops of the uprights in each row are connected by an upper beam extending in a left-right direction. Tie rods are inserted in the front and rear of each upright. The tie rods each have an upper end protruding from the top of the upper beam and fixed to the upper beam by an upper nut and a lower end protruding from the bottom of the workbench and fixed to the workbench by a lower nut. A central cylinder is provided at the center of the upper beam. Side cylinders are symmetrically arranged on the left and right of the central cylinder. The lower ends of plungers of the central cylinder and the side cylinders are fixedly connected to a top of a slider.

An electro-hydrostatic drive for realizing a rapid movement during a rapid movement phase, a force-building movement during a force-building movement phase. The apparatus comprises a hydro-machine with variable volume and/or rotational speed, driven by an electric motor, for providing a volume-stream of a hydraulic fluid, a first cylinder with a piston chamber, an rod chamber, and a plunger rod, a reservoir, a pressure source, a relief valve, a check valve, a fluid connection between the piston chamber and the hydro-machine, a fluid connection between the rod chamber and the hydro-machine, a fluid connection between the piston chamber and the reservoir, a fluid connection between the rod-chamber-side port of the hydro-machine and the reservoir, a fluid connection, through the relief valve, between the reservoir and the pressure source. The relief valve is for pressure safety of the reservoir, and the check valve has a fluid connection from the pressure source to the rod-chamber-side port of the hydro-machine, during the rapid movement phase, a first part of the hydraulic fluid is piped through the fluid connection between the piston chamber and the hydro-machine and the fluid connection between the rod chamber and the hydro-machine, and a second part of the hydraulic fluid communicates through the fluid connection between the piston chamber and the reservoir, during the force-building movement phase, a first part of the hydraulic fluid is piped through the fluid connection between the piston chamber and the hydro-machine and the fluid connection between the rod chamber and the hydro-machine, and a second part of the hydraulic fluid is piped through the fluid connection between the rod-chamber-side port of the hydro-machine and the reservoir.

The press machine includes: a hydraulic cylinder configured to drive a slide; a plurality of hydraulic pumps/motors; a first port of each of which is connected to a first pressurizing chamber of the hydraulic cylinder; a plurality of servomotors axially connected to rotating shafts of the respective hydraulic pumps/motors respectively; a low-pressure accumulator to which second ports of the hydraulic pumps/motors are each connected; a high-pressure accumulator connected to a second pressurizing chamber of the hydraulic cylinder; and a slide position controller configured to control the servomotors so that a position of the slide matches a position corresponding to a slide position command signal based on the slide position command signal from a slide position commander and a slide position signal from a slide position detector.

A hydraulic forging press machine and a control method, whereby surging of the forging load or dead zones where the forging speed goes to zero is suppressed, and forging is performed with high precision throughout a wider range than the prior art, from low to high load. Pressure cylinders have a main pressure cylinder configured so working fluid is supplied during forging, and secondary pressure cylinders are configured so supplying and stopping of the supply of working fluid thereto are switched in response to the forging load, head-side hydraulic chambers of the secondary pressure cylinders being connected to a head-side hydraulic chamber of the main pressure cylinder via electromagnetic switching valves. Only the main pressure cylinder is used until the forging load exceeds a set load, and the number of secondary pressure cylinders used is sequentially increased as the forging load increases after the forging load exceeds the set load.

The present invention provides an improved high-low hydraulic system for compacting machinery, such as balers, horizontal balers, compactors, transfer station compactors, and the like. The high-low hydraulic system comprises at least one double rotary pump, a plurality of directional control valves, a pilot-operated back pressure reducing valve, a flow control valve, a plurality of one-way valves, and a plurality of pressure switches. The high-low hydraulic system may be regenerative or non-regenerative and provides many advantages over conventional hydraulic systems. Such advantages include greater system efficiency due to a reduced back pressure during the time of the retraction stroke and clever flow sequencing, mitigation of hydraulic shocks at the beginning and end of compaction and retraction strokes, and reduced cycle time of the cylinder during operation due to the concurrent filling of the rod end side during decompression of the blind end side after the compaction stroke. Moreover, the present high-low hydraulic system allows for the cylinder to operate at three or more independent speeds. Additionally, the present high-low hydraulic system may also comprise an accumulator and pressure transducer that further assist with substantially maintaining a predetermined hydraulic pressure on the blind end side after the completion of the compaction stroke.

A hydraulic accumulator including an energy storage apparatus with a first piston face configured to reversibly compress an energy storage medium and a second piston face forming at least part of an inner surface of a corresponding second fluid chamber reversibly expandable by movement of the second piston face. A third piston face forms at least part of an inner surface of a corresponding third fluid chamber reversibly expandable by the third piston face. The first, second and third piston faces are coupled together.

A hydraulic drive system associable with a multi-press punching apparatus for operating a plurality of punching tools includes a plurality of hydraulic cylinders provided with respective pistons defining thrust chambers and return chambers inside the hydraulic cylinders and associated with corresponding punching tools, a reversible first pump connected to the thrust chambers and arranged to send oil to, or suck oil from, at least one of the thrust chambers so as to move the respective piston, a plurality of selector valves interposed between the first pump and the thrust chambers of the hydraulic cylinders and activable to connect the first pump to the thrust chambers, and a hydraulic accumulator connected to the return chambers and arranged for maintaining in said return chambers oil at a defined preload pressure.