EP0628730B1 - Système hydraulique, particulièrement pour une presse plieuse - Google Patents

Système hydraulique, particulièrement pour une presse plieuse Download PDF

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Publication number
EP0628730B1
EP0628730B1 EP19940106726 EP94106726A EP0628730B1 EP 0628730 B1 EP0628730 B1 EP 0628730B1 EP 19940106726 EP19940106726 EP 19940106726 EP 94106726 A EP94106726 A EP 94106726A EP 0628730 B1 EP0628730 B1 EP 0628730B1
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EP
European Patent Office
Prior art keywords
valve
chamber
differential cylinder
piston
hydraulic system
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP19940106726
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German (de)
English (en)
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EP0628730A1 (fr
Inventor
Hubert Bernd
Rudolf Stenger
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bosch Rexroth AG
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Mannesmann Rexroth AG
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Application filed by Mannesmann Rexroth AG filed Critical Mannesmann Rexroth AG
Publication of EP0628730A1 publication Critical patent/EP0628730A1/fr
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
    • B30B15/16—Control arrangements for fluid-driven presses
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D5/00—Bending sheet metal along straight lines, e.g. to form simple curves
    • B21D5/02—Bending sheet metal along straight lines, e.g. to form simple curves on press brakes without making use of clamping means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
    • B30B15/28—Arrangements for preventing distortion of, or damage to, presses or parts thereof
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B20/00—Safety arrangements for fluid actuator systems; Applications of safety devices in fluid actuator systems; Emergency measures for fluid actuator systems

Definitions

  • the invention relates to a hydraulic system which is used in particular in connection with a press brake and which has the features from the preamble of claim 1.
  • Press brakes have a top beam, which can usually be moved up and down by two synchronized differential cylinders.
  • a piston in each differential cylinder separates its interior into a piston chamber and an annular chamber and is connected to the upper cheek of the press via a piston rod.
  • the upper cheek first falls during a press cycle due to its weight in rapid traverse, with oil being metered out of the annular spaces of the differential cylinder.
  • the top beam is switched to creep speed, during which the sheet is moved and the sheet is deformed. After a decompression phase, the upper cheek is finally moved up again in rapid traverse.
  • Known hydraulic systems for press brakes include, in addition to the differential cylinders, a proportional directional control valve for each differential cylinder, with which the pressure medium paths between a pump and a tank on the one hand and the differential cylinder on the other hand can be controlled and which has a valve piston which can be moved from a rest position to a working position .
  • the position of the valve piston and thus also the rest position can usually be detected by a position transmitter in order to be able to react quickly and precisely to the respective differential cylinder.
  • the annular space and the piston space of a differential cylinder can be connected to one another via the proportional directional control valve while the upper beam is moving downwards.
  • the proportional directional control valve With this so-called differential circuit, the oil flowing out of the annulus flows through the proportional directional control valve in the piston chamber of the differential cylinder.
  • the differential circuit can be maintained not only in rapid and creep speed before touching the sheet, but also during the deformation of the sheet.
  • the ratio of the piston surface facing the annular space to the piston surface facing the piston space is namely very small and is approximately in the range of 1:10, so that at the same pressure in the annular space and in the piston space, the pressing force is only slightly smaller than in the case in which of the pressing process in the annulus tank pressure prevails (see for example FLUID, Vol. 22, September 1988, pages 37-39, "endurance run with prop technology").
  • a monitored safety valve is understood to mean a valve whose status is determined by a sensor, e.g. by an electrical limit switch, can be detected. With lower safety requirements, a single valve can be sufficient to shut off the annulus. Monitoring can then also be dispensed with. If only one of the two safety valves is in its blocking position during a stop, this can be indicated optically or acoustically. In addition, the machine cannot be started until the defect in the safety valve or in the electrical control has been remedied.
  • the invention has for its object to provide a hydraulic system with the features from the preamble of claim 1 so that the desired control of a differential cylinder and the safety requirements can be met with a few valves.
  • the proportional directional control valve has a first outlet for lifting the upper beam, which can be connected to the annulus of the differential cylinder.
  • the use of the proportional directional control valve as a safety valve is now possible in a simple manner in that the first output in the working position of the valve piston, which it assumes for the downward movement of the upper beam, can be connected to the connection between the pressure side of the pump and the piston chamber of the differential cylinder and can be shut off in the rest position of the valve piston.
  • a proportional directional control valve normally has a first chamber which can be connected to the pressure side of the pump and a second chamber which can be connected to the piston chamber of the differential cylinder.
  • the connection of the first output of the proportional directional control valve to the pressure side of the pump or to the piston chamber of the differential cylinder can now be established indirectly via a third chamber, which is permanently connected only to the first or only to the second chamber and which in the working position of the valve piston with the is connected to the first output and is blocked in the rest position towards the first output.
  • the third chamber is permanently connected to the first chamber or the third chamber within a housing of the proportional directional control valve, so that no additional output of the proportional directional control valve is necessary, which is outside the housing with the input connected to the pressure side of the pump or with the second output of the proportional directional control valve connected to the piston chamber would have to be connected.
  • a direct connection of the first outlet to the first or the third chamber can also be favorable.
  • a first chamber connectable to the pressure side of the pump and a second chamber connectable to the piston chamber of the differential cylinder and a chamber connected to the first outlet the latter being connected directly to the first or through the valve piston in the working position connected to the second chamber and locked in the rest position. It is advantageous here that it is possible to fall back on a common housing manufactured in large quantities, with which only a valve piston already known from practice is used. However, a larger nominal size of the directional control valve could be necessary in a configuration according to claim 5 than in an embodiment according to claims 3 or 4.
  • a proportional directional control valve for a fast-reacting and precise control is usually provided with a displacement sensor with which every actual position of the valve piston can be detected.
  • this displacement sensor is now used as a position sensor for the rest position of the valve piston.
  • one of these safety valves is the proportional directional valve.
  • a 2/2-way valve can be used as the second safety valve, which blocks in the rest position and is open when actuated. Since a slow downward movement of the upper cheek is permissible up to a certain speed, this second safety valve does not have to be leak-free, so that its valve element can be a slide piston.
  • the second safety valve is advantageously designed so that in the rest position it acts as a check valve opening towards the annular space and is open in the actuated position.
  • the pump can only build up pressure in the annular space or in the piston space if two, in particular, monitored safety valves have been brought from a rest position into a working position.
  • One of these two safety valves can in turn be the proportional directional control valve.
  • the other is advantageously, in particular, a pilot-controlled pressure relief valve, which is connected to the pressure side of the pump and the condition of which can be monitored.
  • this pressure relief valve is usually a pilot operated valve with a main piston and with a pilot valve.
  • Such a pressure relief valve can be easily switched to circulation in a manner known per se in that the main piston can be relieved to the tank via a directional valve with a movable valve element.
  • the position of the movable valve element of this directional control valve can now be monitored, thereby achieving the desired high safety standard. It is particularly advantageous here that regardless of the size of the press brake and the desired speeds of the upper cheek and the resulting different amounts of oil flowing into and out of the cylinder rooms, the same monitored safety valve can always be used. A safety valve upstream of the piston space or annular space would have to be adapted to the respective oil quantities.
  • two differential cylinders 10 are provided in the exemplary embodiment shown, each of which houses a piston 11, which is fixed with one emerging from an end face of the differential cylinder Piston rod 12 is connected.
  • the upper cheek of the press brake is attached to the piston rods 12.
  • the piston 11 separates the inside of a differential cylinder 10 into an annular space 13 on the piston rod side and into a cylindrical pressure space 14 away from the piston rod, the circular area of the piston 11 facing the pressure space 14 being approximately ten times as large as the annular area facing the annular space 13.
  • Each differential cylinder 10 is assigned a control block 20 which is identical to the control block of the other differential cylinder and which has a pressure connection P, a tank connection T and two control connections X1 and X2.
  • the control connection X1 is connected to the pressure chamber 14 and the control connection X2 to the annular space 13.
  • a proportional directional control valve 25 is placed on the control block 12, which is a 4/3-way valve and whose valve piston 26 can assume a spring-centered central rest position and work positions on both sides of this rest position. In one working position, the valve piston 26 is brought into operation by actuating one of two electromagnets 27.
  • valve 25 has four connections, of which a pump connection P is connected to this pump connection of the control block via a check valve 28 which blocks the pump connection of the control block 20, a tank connection T to the tank connection T of the control block and a consumer output A to the control output X1 of the control block 20 is.
  • a consumer connection B of the valve 25 can be connected to the control connection X2 of the control block 20.
  • the position of the valve piston 26 can be monitored with a displacement sensor 29 which is arranged on one side of the valve piston 26.
  • a displacement sensor is used which is based on the principle of changing an inductance and which, in a manner known per se, consists of several coils and an iron core, the axial position of which changes within the coils with the position of the valve piston.
  • the displacement sensor 29 it can also be determined whether the valve piston 26 is in the rest position or not.
  • the rest position of the valve piston 26 can also be monitored by a limit switch to comply with safety regulations.
  • a check valve 31 which can be unlocked with the aid of an electromagnet against the force of a spring and which, in its rest position, blocks the consumer outlet B of the valve 25.
  • the rest position of the valve element of the check valve 31 is monitored by a limit switch 32.
  • a pressure relief valve 33 is inserted, which has no function in normal operation, but is only intended to prevent an excessively high pressure in the annular space 13 during commissioning of the system .
  • the two pressure connections P of the two control blocks 20 are connected to a common pressure line 38, in which an oil filter 39 is installed and which is fed by a hydraulic pump 40, which sucks in oil from a tank 41.
  • the pressure line 38 is through a pilot-controlled proportional pressure relief valve 42 is secured, which is connected on the input side to the pressure connection of the hydraulic pump 40 and on the output side to the tank 41 and which is also provided with a maximum pressure protection.
  • a main piston 49 of the pressure relief valve 42 can be relieved by a 2/2-way valve 43, via which a control port X of the pressure relief valve 42 is connected to the tank 41 in the rest position. If the directional control valve 43 has been actuated with the aid of an electromagnet 44, the control connection X is shut off.
  • the rest position of a movable valve element 48 of the directional control valve 43 can be detected with a limit switch 45 assigned to the valve 43.
  • a suction valve 46 is placed on the control block 20 and is connected on the one hand to the control connection X1 of the control block and on the other hand to a tank line 47 leading from the tank connection of the control block 20 to the tank 41.
  • the suction valve 46 can be unlocked by pressurizing a control line 48.
  • Both control lines 48 are connected to an output of a directional valve 50, which is connected to the common pressure line 38 in the rest position of the valve 50 and is relieved towards the tank in the actuated position of the valve 50.
  • valves When the pistons 11 and with them the upper cheek of a press brake rest, the valves assume the positions shown in FIG. 1.
  • the annular space 13 of the differential cylinder 10 is blocked off from the tank by the two valves 25 and 31, which are monitored and can thus serve as safety valves.
  • a pressure build-up in the annular space 13 is not possible even when the pump is running, since in the rest position of the valve 25 all connections of this valve are blocked and since the main piston of the pressure relief valve 42 is relieved by the directional control valve 43.
  • the valve 25 and the valve 43 are used together with the valve 42 as safety valves. Both valves also serve as safety valves against pressure build-up in the pressure chamber 14.
  • valve 31 is switched to flow.
  • the valve 25 is actuated so that the consumer outlet B is connected to the connection between the pressure connection P and the consumer outlet A.
  • the amount of oil that flows out of the annular space 13 and via the valve 25 to the pressure space 14 is now metered with the valve 25.
  • the still missing amount of oil for the pressure chamber 14 is sucked out of the tank 41 via the valve 46.
  • the valve 43 is open, so that the pump 40 circulates via the pressure relief valve 42.
  • the upper cheek is stopped just above the sheet to be machined by resetting the valve 25. It should now be moved slowly to the sheet metal and then deform the sheet metal.
  • the directional valve 43 is now actuated so that the pump 40 can generate a pressure.
  • the proportional directional control valve 25 is adjusted in the same direction as during the rapid traverse so that oil conveyed by the pump 40 reaches the piston chamber 14 in a metered manner.
  • the pressure is initially e.g. about ten times as high as in the piston chamber 14 before the upper cheek hits the sheet to be deformed and a pressure determined in the pressure chamber 14 is determined by the deformation work to be performed.
  • the valve 50 was actuated during the downward movement of the upper cheek. During the subsequent upward movement, the valve 50 returns to its rest position, so that the suction valves 47 are unlocked.
  • the proportional directional control valve 25 is brought from the rest position in the other direction into a working position in which the outlet B is connected to the pressure inlet P and the outlet A is connected to the tank connection T.
  • the flow cross section between P and B can now be used to determine the speed at which the piston 11 moves upwards. Oil, which is displaced from the pressure chamber 14 and cannot flow to the tank via the valve 25, reaches the tank via the suction valve 46.
  • FIGS. 2 to 6 the housing 60 of a proportional directional control valve 25 that can be used in the system according to FIG. 1 is to be indicated by the dash-dotted line.
  • the usual switching symbol for a valve is only intended to identify the valve piston 26.
  • Such a valve piston 26 is usually located in a bore in the housing 60, this bore being provided with various annular chambers which are connected to the externally visible connections of the valve. These annular chambers are symbolized in FIGS. 2 to 6 by the U-shaped characters between the valve pistons and the housings 60.
  • valve according to FIG. 2 which is the same valve as in FIG. 1, that a total of four valve chambers are present.
  • a first valve chamber 61 is connected to the pressure connection P, a second valve chamber 62 to the outlet A, a third valve chamber 63 to the outlet B and a fourth valve chamber 64 to the tank connection T. It can be seen that in one working position of the valve 25, the chamber 63 is connected directly to the chamber 61 or the chamber 62 via the valve piston 26.
  • valve 25 in addition to the valve chambers 61 to 64, there is a further valve chamber 65 which has a connection to the valve chamber 61 within the housing 60. In one working position, the chamber 63 is connected via the piston 26 to the chamber 65 and via this to the chamber 61.
  • FIG. 4 The embodiment according to FIG. 4 is very similar to that from FIG. 3. However, the chambers 61 and 65 are connected to one another outside the housing 60.
  • valve chamber 65 which, in the embodiment according to FIG. 5, is connected inside the housing 60 and in the embodiment according to FIG. 6 outside the housing 60 with the valve chamber 62 is.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)

Claims (10)

  1. Une installation hydraulique pour une presse, en particulier pour une presse-plieuse, muni d'un vérin différentiel (10), lequel présente un piston (11) qui sépare une chambre du piston (14) d'une chambre annulaire (13) et qui est relié à une mâchoire supérieure de la presse, laquelle mâchoire peut être mue vers le haut et en avance rapide et en course de presse mue vers le bas, muni également d'un distributeur à action proportionnelle (25), lequel permet de commander les voies véhiculant la pression entre une pompe (40), un réservoir (41) et les chambres (13, 14) du vérin différentiel (10), et lequel présente un tiroir de distributeur (26) qui peut coulisser d'une position de repos vers une position de travail, la position de repos pouvant en particulier être saisie par un capteur de position (29), cependant que, pendant l'avance rapide de la mâchoire supérieure, la pompe (40) alimente le réservoir (41) en circulation, que le fluide véhiculant la pression peut être refoulé de manière dosée, à partir de la chambre annulaire (13) du vérin différentiel (10) vers la chambre du piston (14) du vérin différentiel (10) au travers du distributeur à action proportionnelle (25), lequel se trouve dans sa position de travail, et qu'il peut être réaspiré, à partir du réservoir (41) vers la chambre du piston (14) du vérin différentiel (10) au travers d'une valve de réaspiration (46), et cependant que, pendant la course de presse de la mâchoire supérieure, le fluide véhiculant la pression alimenté par la pompe (40) et celui refoulé de la chambre annulaire (13) peuvent être amenés de manière dosée vers la chambre du piston (14) du vérin différentiel (10) au travers du distributeur à action proportionnelle (25), caractérisée en ce que la chambre annulaire (13) du vérin différentiel (10) peut être isolée sans fuite de la pompe (40) et du réservoir (41) par le distributeur à action proportionnelle (25) dans la position de repos de celui-ci.
  2. Une installation hydraulique conforme à la revendication n° 1, caractérisée en ce que un premier port (B) du distributeur à action proportionnelle (25), pouvant être connecté à la chambre annulaire (13) du vérin différentiel (10), peut être relié à la connexion entre le côté pression de la pompe (40) et la chambre du piston (14) du vérin différentiel (10) dans la position de travail du tiroir du distributeur (26) et peut être isolé dans la position de repos du tiroir du distributeur (26).
  3. Une installation hydraulique conforme à la revendication n° 2, caractérisée en ce que le distributeur à action proportionnelle (25) présente une première chambre de valve (61), qui peut être reliée au côté pression de la pompe (40), une deuxième chambre de valve (62), qui peut être reliée à la chambre du piston (14) du vérin différentiel (10), et une troisième chambre de valve (65), qui en permanence n'est reliée qu'à la première chambre de valve (61) ou qu'à la deuxième chambre de valve (62), et que la troisième chambre de valve (65) au travers du tiroir du distributeur (26) est reliée au premier port (B) dans sa position de travail et est isolée du premier port (B) dans sa position de repos.
  4. Une installation hydraulique conforme à la revendication n° 3, caractérisée en ce que la troisième chambre de valve (65) dans un corps (60) du distributeur à action proportionnelle (25) est reliée en permanence à la première chambre de valve (61) ou à la deuxième chambre de valve (62).
  5. Une installation hydraulique conforme à la revendication n° 2, caractérisée en ce que le distributeur à action proportionnelle (25) présente une première chambre de valve (61), qui peut être reliée au côté pression de la pompe (40), une deuxième chambre de valve (62), qui peut être reliée à la chambre du piston (14) du vérin différentiel (10), ainsi qu'une chambre de valve (63) reliée au premier port (B) et que cette dernière au travers du tiroir du distributeur (26) est reliée directement à la première chambre de valve (61) ou la deuxième chambre de valve (62) dans sa position de travail et est isolée dans sa position de repos.
  6. Une installation hydraulique conforme à une des revendications précédentes, caractérisée en ce que le distributeur à action proportionnelle (25) est muni d'un capteur de position (29) pour le tiroir du distributeur (26) et que ce capteur de position (29) est utilisé pour indiquer la position de repos du tiroir du distributeur (26).
  7. Une installation hydraulique conforme à une des revendications précédentes, caractérisée en ce que entre le distributeur à action proportionnelle (25) et la chambre annulaire (13) du vérin différentiel (10) est disposé un distributeur (31) particulièrement surveillé, qui dans sa position de repos isole le distributeur à action proportionnelle (25) de la chambre annulaire (13), à la manière d'un clapet anti-retour, et dans sa position de travail est ouvert.
  8. Une installation hydraulique conforme à une des revendications précédentes, caractérisée en ce que un limiteur de pression en particulier piloté (42) est relié côté pression à la pompe (40), cependant que son état peut en particulier être surveillé.
  9. Une installation hydraulique conforme à la revendication n° 8, caractérisée en ce que le limiteur de pression piloté (42) comporte un tiroir principal (49), lequel peut être déchargé au travers d'un distributeur (43) avec un élément de distributeur (48) mobile, qu'en particulier la position de l'élément de distributeur (48) peut être saisie par un capteur de position (45) et que le distributeur (43) est ouvert dans sa position de repos.
  10. Une installation hydraulique conforme aux revendications nos 8 et 9, caractérisée en ce que sont prévus deux vérins différentiels (10), commandés de manière synchrone, qui peuvent être reliés à une tuyauterie de pression (38) commune, et que le limiteur de pression piloté (42) est raccordé à la tuyauterie de pression (38) commune.
EP19940106726 1993-05-05 1994-04-29 Système hydraulique, particulièrement pour une presse plieuse Expired - Lifetime EP0628730B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4314801 1993-05-05
DE4314801A DE4314801B4 (de) 1993-05-05 1993-05-05 Hydraulische Anlage, insbesondere für eine Abkantpresse

Publications (2)

Publication Number Publication Date
EP0628730A1 EP0628730A1 (fr) 1994-12-14
EP0628730B1 true EP0628730B1 (fr) 1997-06-25

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Families Citing this family (10)

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Publication number Priority date Publication date Assignee Title
DE29710127U1 (de) 1997-06-10 1997-08-14 Heilmeier & Weinlein Fabrik für Oel-Hydraulik GmbH & Co KG, 81673 München Elektrohydraulische Spannvorrichtung
EP1211059B1 (fr) * 2000-12-02 2006-08-16 Bosch Rexroth AG Commande hydraulique pour combinaison embrayage-frein à actionnement hydraulique en particulier pour l'arbre excentrique d'une presse mécanique
DE10344480B3 (de) 2003-09-24 2005-06-16 Sauer-Danfoss Aps Hydraulische Ventilanordnung
CN102852905B (zh) * 2012-07-25 2015-01-28 浙江工业大学 气马达比例调速实验系统
CN102854805B (zh) * 2012-07-25 2014-11-12 浙江工业大学 气动马达的比例调速系统
ES2839073T3 (es) * 2015-07-06 2021-07-05 Feintool Int Holding Ag Dispositivo y procedimiento para el control del accionamiento principal de una prensa troqueladora de precisión
DE102016118854A1 (de) 2016-10-05 2018-04-05 Hoerbiger Automatisierungstechnik Holding Gmbh Elektrohydraulische Antriebseinheit
DE102016118853B3 (de) * 2016-10-05 2017-10-26 Hoerbiger Automatisierungstechnik Holding Gmbh Elektrohydraulische Antriebseinheit
RU2731468C1 (ru) * 2019-11-21 2020-09-03 Федеральное государственное бюджетное образовательное учреждение высшего образования "Норильский государственный индустриальный институт" Гидравлический пресс
CN114718921B (zh) * 2022-02-15 2025-06-17 北京航天发射技术研究所 一种高可靠后倒式火箭摆杆液压系统及控制方法

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SE316379B (fr) * 1965-05-20 1969-10-20 Trima Ab
DE3121340A1 (de) * 1981-05-29 1982-12-16 Wabco Steuerungstechnik GmbH & Co, 3000 Hannover Druckmittelbetaetigte steuereinrichtung
DE3219730A1 (de) * 1982-05-26 1983-12-01 Robert Bosch Gmbh, 7000 Stuttgart Einrichtung zur steuerung eines hydraulischen servomotors
DE3631104A1 (de) * 1986-09-12 1988-03-24 Rexroth Mannesmann Gmbh Sicherheitsschaltung, insbesondere fuer eine presse
DE3732717A1 (de) * 1987-09-29 1989-04-06 Smg Sueddeutsche Maschinenbau Sicherheitssteuerung fuer hydraulische pressen
FR2674460A1 (fr) * 1991-03-27 1992-10-02 Mercier J Perfectionnements aux presses hydrauliques, en particulier aux presses-plieuses a tole.

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DE4314801B4 (de) 2004-09-09
DE4314801A1 (de) 1994-11-10
EP0628730A1 (fr) 1994-12-14

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