In an apparatus and a method for controlling the primary drive of a hydraulically driven fine blanking press, the hydraulic circuit is simplified due to the elimination of hydraulic tubes, and the amount of hydraulic fluid is reduced, while increasing the number of strokes and achieving a simple design for the press.

In a machine press with a lower and an upper tool support, a closed hydraulic drive system acts upon the upper tool support. This system has at least one hydraulic drive unit, which includes at least one hydraulic cylinder-piston unit and at least one hydraulic assembly acting upon this unit and supplied from a storage reservoir. A base pressure above environmental pressure constantly prevails in the storage reservoir. The storage reservoir is designed as a cylinder store with a hydraulic chamber defined by a cylinder and a piston unit displaceably guided therein. The piston unit is acted upon on its side functionally opposite the hydraulic chamber by a hydraulic fluid chamber which for its part is connected to a high-pressure gas store. The active surface of the hydraulic fluid chamber on the piston unit is small compared to the active surface of the hydraulic chamber on the piston unit.

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.

An electrohydraulic drive unit is provided, comprising a cylinder-piston assembly having a piston-side first hydraulic working chamber and a piston-rod-side second hydraulic working chamber, a tank, a hydraulic pump, which can be driven at variable rotational speed and which has a tank connection point and a working connection point, a valve assembly, which is connected between the working connection point of the hydraulic pump and the cylinder-piston assembly, and an anti-cavitation valve, which is connected between the tank and the first hydraulic working chamber; and a machine controller. Switching valves of the valve assembly can be switched between loading of the first hydraulic working chamber and loading of the second hydraulic working chamber of the cylinder-piston assembly during pumping operation of the hydraulic pump from the working connection point of the hydraulic pump by the machine controller.

A hydraulic drive including a differential cylinder that has a first pressure chamber and a second pressure chamber and a differential piston, a first hydraulic pump that includes a pump intake and a pump outlet, a directional control valve having a first switching position and a second switching position, a high pressure tank, and an additional hydraulic cylinder that includes an additional pressure chamber hydraulically connected with the pump intake and with the high pressure tank and an additional piston limiting the additional pressure chamber, the differential piston being movably coupled with the additional piston, wherein in the first switching position of the directional control valve the first pressure chamber is hydraulically connected with the second pressure chamber, and in the second switching position of the directional control valve the second pressure chamber is not hydraulically connected with the first pressure chamber.

There is provided a press machine which can apply a large compression force to a mold as well as impart smooth vibration only in a rectilinear advancing direction to the mold, and thereby can improve the press-formability. A main slide and a sub-slide constitute a slide and at the same time a cylinder-piston mechanism. During press-forming, a compression force is transmitted to the sub-slide (an upper mold) through hydraulic pressure applied interlockingly with driving of the main slide, and the sub-slide is vibrated with the hydraulic pressure being periodically changed. Favorable press-forming can be performed even under relatively difficult press-forming conditions, by controlling the vibration such that a vibration frequency of the sub-slide (the upper mold) becomes 9 Hz or higher but 33.3 Hz or lower and a vibration amplitude of the sub-slide becomes 0.05 mm or larger but 0.5 mm or smaller.

An actuator device includes two drive units for an actuator output element. The first drive unit has a first piston chamber and a first piston displaceable therein and also first hydraulic means for displacing the piston. The second drive unit has a second piston chamber and a second piston displaceable therein and also second hydraulic or pneumatic means for displacing the piston. The second piston is joined to the actuator output element for conjoint movement therewith and can be coupled to the first piston for thrust, so that the second piston is displaceable in an outward direction by the first piston. The first drive unit is configured for a larger thrust force than the second drive unit, while the second drive unit is designed for a greater stroke speed than the first drive unit.

A high-speed hydraulic forging press is disclosed. The high-speed hydraulic forging press includes a forging hammer, a movable beam, a main hydraulic cylinder, a single-rod elevation hydraulic cylinder, a plurality of main hydraulic pumps, a high-pressure energy accumulator, an intermediate-pressure energy accumulator, an oil tank, a programmable logic controller and a valve-regulation system. During a rolling process, when a rolling resistance applied to the forging hammer increases to cause pressure in the main hydraulic cylinder to reach a predetermined value, the programmable logic controller controls the valve-regulation system so that the high-pressure energy accumulator stops supplying the hydraulic oil to the main hydraulic cylinder, and that the hydraulic oil in the main hydraulic cylinder is supplied by at least one of the plurality of main hydraulic pumps. The high-speed hydraulic forging press exhibits remarkable advantages including a reasonable resource allocation, a simple structure, low equipment investment, and high energy utilization.

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.

A part of kinetic energy during lowering of a slide of a press machine is converted into oil hydraulic energy by a first oil hydraulic cylinder, and the converted oil hydraulic energy (hydraulic oil having boosted first system pressure) is stored in a first accumulator. The hydraulic oil having the first system pressure stored in the first accumulator is discharged in knockout process, a second oil hydraulic cylinder that functions as a knockout cylinder is raised to perform knockout operation of a product worked by the press machine. Consequently, it is possible to perform knockout operation without using a dedicated driving source such as an oil pressure source and an air pressure source, and provide a low-cost hydraulic knockout device.