Abstract: A hydraulic drive carries out a method for discretely changing a positional output on the hydraulic drive. At least one displacement cylinder incrementally supplies or discharges the cylinder volume to or from the drive by displacing the cylinder piston element from a starting to an end position depending on at least one input signal. The piston element is repeatedly displaced from starting to end position and back to discretely change the positional output correspondingly to the supplied or discharged displacement volume. The cylinder is hydraulically connected to a pressure medium source supply or return line while displacing the piston element from starting to end position. The changed positional output is restored in a successive step. The cylinder chambers of the displacement cylinder are hydraulically short-circuited by a short-circuit line hydraulically separated from the supply or return line when returning the piston element from the end to the starting position.

Abstract: A drive device for a bending press, in particular a press brake, with a press frame includes a stationary press beam and has a press beam which can be displaced relative to the press beam by a beam adjusting device formed by a closed hydraulic system including a hydraulic pump with a controllable drive motor, at least one control valve and at least one hydraulic linear actuator. The linear actuator includes a first piston arrangement with a first piston dividing a cylinder chamber into a first pressure chamber and a second pressure chamber and, in another cylinder chamber, a second piston arrangement with another piston and at least one other pressure chamber. The first piston arrangement and the second piston arrangement are coupled with one another.

Abstract: A hydraulic drive carries out a method for discretely changing a positional output on the hydraulic drive. At least one displacement cylinder incrementally supplies or discharges the cylinder volume to or from the drive by displacing the cylinder piston element from a starting to an end position depending on at least one input signal. The piston element is repeatedly displaced from starting to end position and back to discretely change the positional output correspondingly to the supplied or discharged displacement volume. The cylinder is hydraulically connected to a pressure medium source supply or return line while displacing the piston element from starting to end position. The changed positional output is restored in a successive step. The cylinder chambers of the displacement cylinder are hydraulically short-circuited by a short-circuit line hydraulically separated from the supply or return line when returning the piston element from the end to the starting position.

Abstract: The invention relates to a drive device (1) for a bending press, in particular a folding press (2), comprising a press frame (3), a press table (9) and a press beam (11) that can be adjusted relative to the press table (9) via a hydraulic system (18) comprising a hydraulic pump (47), controlled drive motor (45), switch and control means and pressure lines and at least one pressure cylinder (12) which can be supplied with at least one pressure medium. The hydraulic system (18) forms a closed system together with a ring line (44) comprising the hydraulic pump (47), control valves (39, 41, 58, 84, 86, 87, 88, 89) and a pressure store (57). The ring line comprises a first line section (51) between a pressure chamber (23) of the pressure cylinder (12) and the hydraulic pump (47) and a second line section (53) between an additional pressure chamber (22) of the pressure cylinder (12) and the hydraulic pump (47).

Abstract: The invention relates to a drive device (1) for a bending press (3), in particular a press brake, with a press frame (10) comprising a stationary press beam (2) and having a press beam (4) which can be displaced relative to the press beam (2) by means of a beam adjusting device (6) formed by a closed hydraulic system (5) comprising a hydraulic pump (46) with a controllable drive motor (47), at least one control valve (48) and at least one hydraulic linear actuator (7). The linear actuator (7) comprises a first piston arrangement (25) with a first piston (27) dividing a cylinder chamber (34) into a first pressure chamber (35) and a second pressure chamber (37) and, in another cylinder chamber (39), a second piston arrangement (26) with another piston (28) and at least one other pressure chamber (40). The first piston arrangement (25) and the second piston arrangement (26) are coupled with one another.

Abstract: The invention relates to a drive device (1) for a bending press, in particular a folding press (2), comprising a press frame (3), a press table (9) and a press beam (11) that can be adjusted relative to the press table (9) via a hydraulic system (18) comprising a hydraulic pump (47), controlled drive motor (45), switch and control means and pressure lines and at least one pressure cylinder (12) which can be supplied with at least one pressure medium. The hydraulic system (18) forms a closed system together with a ring line (44) comprising the hydraulic pump (47), control valves (39, 41, 58, 84, 86, 87, 88, 89) and a pressure store (57). The ring line comprises a first line section (51) between a pressure chamber (23) of the pressure cylinder (12) and the hydraulic pump (47) and a second line section (53) between an additional pressure chamber (22) of the pressure cylinder (12) and the hydraulic pump (47).

Abstract: A valve comprises an electromagnetic actuator including a solenoid. The solenoid includes at least one core and an anchor plate. The solenoid further comprises at least one coil disposed within the core and connected to a set of power electronics to supply current to the coils. The actuator further comprises a plunger connected to the anchor plate and at least one spring configured to guide the plunger. The actuator also includes a pressure compensation system. The opening and closing of the valve is controlled by passing current through the coil.

Abstract: An on-off valve is disclosed, especially a fast-acting on-off valve, wherein a plunger is pretensioned in a base position. The plunger has a plurality of parallel control edges via which a plurality of sectional opening cross-sections, arranged in parallel in a hydraulic manner, can be jointly actuated to open or close when the valve is switched.

Abstract: An on-off valve is disclosed, especially a fast-acting on-off valve, wherein a plunger is pretensioned in a base position. The plunger has a plurality of parallel control edges via which a plurality of sectional opening cross-sections, arranged in parallel in a hydraulic manner, can be jointly actuated to open or close when the valve is switched.

Abstract: A valve comprises an electromagnetic actuator including a solenoid. The solenoid includes at least one core and an anchor plate. The solenoid further comprises at least one coil disposed within the core and connected to a set of power electronics to supply current to the coils. The actuator further comprises a plunger connected to the anchor plate and at least one spring configured to guide the plunger. The actuator also includes a pressure compensation system. The opening and closing of the valve is controlled by passing current through the coil.

Abstract: Valve drive with a first actuator (1) for opening and/or closing a gas-exchange valve (2), in particular of an internal combustion engine, and a separate second actuator (3) for the valve-play compensation of the gas-exchange valve (2), the second actuator (3) being developed as a double-action, preferably hydraulic, piston cylinder arrangement with at least two working surfaces (A1, A2) that can be subjected to pressure.

Abstract: A fully variable hydraulic valve drive comprising a hydraulic drive unit which is acted upon with hydraulic fluid for opening and closing a valve wherein the drive unit of the valve in the closing or opening stroke movement acts on an intermediate storage means with hydraulic fluid under pressure, wherein this hydraulic fluid which is stored under pressure in the intermediate storage means then drives the drive unit of the valve again in the opposite stroke movement.

Abstract: In a strand guide for a continuous casting plant comprising a plurality of strand supporting elements for supporting the strand, in particular support segments carrying supporting rollers, several support segments being fastened adjacent each other on a supporting framework designed in one piece in its longitudinal extension, each support segment is fastened to the supporting framework by a fixed bearing and a movable bearing spaced apart therefrom in the longitudinal extension of the strand guide, each support segment, by at least one bearing, is pivotally mounted to the supporting framework so as to be pivotable about an axis, the axis being oriented transversely with respect to the longitudinal extension of the strand guide and horizontally, as well as in a vertical plain passing through the longitudinal extension of the supporting framework and by at least one bearing is mounted so as to be adjustable with respect to the supporting framework in a direction toward the pivoting movement of the support segme

Abstract: An adjustment device for adjusting the position of at least one strand supporting element (5) relative to a supporting stand (9, 10) carrying at least one further strand supporting element (6), of a strand guide in a continuous casting plant comprises at least one hydraulic adjustment cylinder (12) contacting a strand supporting element (5) directly or indirectly on the one side and the supporting stand (9, 10) carrying a further strand supporting element (6) on the other side, the movement of the strand supporting element (5) being detectable via a position sensor (17) and controllable by means of an automatic controller (26). In order to safely attain the high precision in positioning the strand supporting elements (5, 6) sought for a strand guide at yet a minimum expenditure and a minimum susceptibility to failure, at least one directional control valve (21A, 21B) capable of being switched via a three-level controller (26) is provided for actuating the hydraulic adjustment cylinder (12) FIG. 2.

Abstract: A device for controlling a hydrostatic drive (1) having a resonator (2) which is connected on the one hand to the hydrostatic drive (1) and on the other hand to a pressurized-fluid supply line (4) and to a return line (5), and having a periodically actuatable switch valve (3) which connects the resonator (2) alternately with the pressurized-fluid supply line (4) and the return line (5). In order to assure advantageous control conditions, the resonator (2) has at least one pressure chamber (6) with a movable, oscillatable chamber limitation (7) for changing the chamber volume movable chamber limitation (7) form a part of a single-mass oscillator comprising mass and spring (10). The pressure chamber (6) which can be connected alternately with the pressurized-fluid supply line (4), the return line (5) and the hydrostatic drive (1) can be acted on via the switch valve (3) with a switch frequency which lies in the supraresonance region of the single-mass oscillator.

Abstract: A device for the operation of a hydrostatic drive (1) having a periodically operable switch valve (2) which connects a resonant pipe (4) connected with the hydrostatic drive (1) for the formation of standing pressure waves in the hydraulic fluid under resonant conditions alternately to a pressure-fluid supply line (5) and to a return line (6). In order to create advantageous control condition, the resonant pipe (4) has a pressure outlet (7) in an oscillation node in the standing pressure waves, and that the switch times of the switch valve (2) be controllable with constant switch frequency.

Abstract: With a continuous casting mold, the mold side walls each are formed by a supporting wall and an internal plate fastened thereto and getting into contact with the metal melt. On the side of the internal plate facing the supporting wall parallely arranged coolant channels are provided, which are designed as slits open towards the supporting wall and whose width is smaller and whose depth is larger, than the width of the ribs located between the slits. In order to render the cooling performance particularly effective, the width of the cooling ribs is smaller than, or equal to, 13 mm and the flow speed of the coolant is adjusted such that the heat transmission coefficient alpha between the internal plate and the coolant is between 20 and 70 kW/m.sup.2 K, preferably between 25 and 50 KW/m.sup.2 K, such that the heat flow density for the internal plate is larger than the heat flow density for a smooth internal plate having no ribs.