EP2643125B1 - Electro-hydraulic pressing device - Google Patents

Electro-hydraulic pressing device Download PDF

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Publication number
EP2643125B1
EP2643125B1 EP20120778337 EP12778337A EP2643125B1 EP 2643125 B1 EP2643125 B1 EP 2643125B1 EP 20120778337 EP20120778337 EP 20120778337 EP 12778337 A EP12778337 A EP 12778337A EP 2643125 B1 EP2643125 B1 EP 2643125B1
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EP
European Patent Office
Prior art keywords
piston
pressure
chamber
electro
pressing device
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.)
Active
Application number
EP20120778337
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German (de)
French (fr)
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EP2643125A1 (en
Inventor
Volker Reichel
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.)
Novopress GmbH Pressen und Presswerkzeuge and Co KG
Original Assignee
Novopress GmbH Pressen und Presswerkzeuge and Co KG
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Publication of EP2643125A1 publication Critical patent/EP2643125A1/en
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Publication of EP2643125B1 publication Critical patent/EP2643125B1/en
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
    • B25B27/00—Hand tools, specially adapted for fitting together or separating parts or objects whether or not involving some deformation, not otherwise provided for
    • B25B27/14—Hand tools, specially adapted for fitting together or separating parts or objects whether or not involving some deformation, not otherwise provided for for assembling objects other than by press fit or detaching same
    • B25B27/146—Clip clamping hand tools
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
    • B25B27/00—Hand tools, specially adapted for fitting together or separating parts or objects whether or not involving some deformation, not otherwise provided for
    • B25B27/02—Hand tools, specially adapted for fitting together or separating parts or objects whether or not involving some deformation, not otherwise provided for for connecting objects by press fit or detaching same
    • B25B27/10—Hand tools, specially adapted for fitting together or separating parts or objects whether or not involving some deformation, not otherwise provided for for connecting objects by press fit or detaching same inserting fittings into hoses
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25F—COMBINATION OR MULTI-PURPOSE TOOLS NOT OTHERWISE PROVIDED FOR; DETAILS OR COMPONENTS OF PORTABLE POWER-DRIVEN TOOLS NOT PARTICULARLY RELATED TO THE OPERATIONS PERFORMED AND NOT OTHERWISE PROVIDED FOR
    • B25F5/00—Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
    • B25F5/005—Hydraulic driving means
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R43/00—Apparatus or processes specially adapted for manufacturing, assembling, maintaining, or repairing of line connectors or current collectors or for joining electric conductors
    • H01R43/04—Apparatus or processes specially adapted for manufacturing, assembling, maintaining, or repairing of line connectors or current collectors or for joining electric conductors for forming connections by deformation, e.g. crimping tool
    • H01R43/042—Hand tools for crimping
    • H01R43/0428—Power-driven hand crimping tools

Definitions

  • the invention relates to an electro-hydraulic pressing device, in particular for producing pipe connections by means of press fittings and for producing crimp connections in electrical engineering.
  • Such a pressing device as for example in DE 20 2004 000 215 U is described, for example, has two pliers-like pressing jaws. These are actuated by an electro-hydraulic drive.
  • a pressure piston is provided in a piston chamber, the pressure chamber is connected to the hydraulic pump.
  • the pressure piston is moved by pumping fluid into the pressure chamber.
  • the pressing jaws are closed, wherein the pressure piston possibly actuates the pressing jaws via a roller head.
  • so-called press loops are also known pliers-like pressing devices known. These have a plurality of articulated pressing jaws, which are wrapped, for example, around a press fitting to be pressed.
  • the opening of the press sling is connected to a pressing device, so that compression takes place by contraction of the press sling.
  • the pressing device used in this case is essentially corresponding to that in the DE 20 2004 000 215 U formed pressing device described.
  • axial compression devices are known in which also the pressure buildup is electro-hydraulic to move a pressure piston.
  • a control valve In the hydraulic pump connecting to the pressure chamber flow channel, a control valve is also provided. Upon reaching the cut-off pressure decreases due to the opening of the pressure relief valve, the pressure in the pressure chamber and thus also in the connecting channel between the hydraulic pump and the pressure chamber. This leads to switching of the control valve, whereby a return flow is opened.
  • the return flow channel connects the pressure chamber with the fluid reservoir.
  • the control valve is here in DE 20 2004 000 215 such that fluid is pumped from the hydraulic pump through a narrow channel provided in the valve piston of the control valve during the injection process. Upon reaching the cut-off pressure and thus decreasing the pressure in the pressure chamber, the spring-loaded valve piston of the control valve is displaced and releases the return flow channel.
  • the pushing back of the pressure piston in the starting position is effected by a return spring disposed in the pressure chamber. This presses when resetting the fluid present in the pressure chamber through the control valve free given return flow into the reservoir.
  • a disadvantage of the in the DE 20 2004 000 215 described pressing device is that in order to carry out the pressing operation, the hydraulic fluid from the hydraulic pump must be pumped through the small cross-section opening in the control valve. This affects the efficiency. Furthermore, openings with a small cross section are susceptible to contamination.
  • an electro-hydraulic pressing device known.
  • a needle valve is arranged in the return flow. This needle valve is opened upon reaching the cut-off, so that the hydraulic fluid is pushed back from the pressure chamber by means of the return spring in the reservoir.
  • the needle valve arranged in the return flow channel has a channel with a small cross section which is closed with the valve needle during the pressing process. Since here too a channel is provided with a small cross-section, through which the fluid must be pressed through, the efficiency of the in DE 198 25 160 described pressing device when pushing back the pressure piston low. Furthermore, there is also the disadvantage that the channel provided in the needle valve slightly contaminates with a small cross section.
  • a similar electro-hydraulic pressing device is off DE 20 2006 001 889 U1 known.
  • This also has a pressing jaw acting on the pressure piston, through which a piston chamber is divided into a pressure chamber and a rear space.
  • a hydraulic pump hydraulic fluid is conveyed from a reservoir into the pressure chamber.
  • a return spring for pushing back the pressure piston is arranged after pressing.
  • a pressure relief valve is arranged in the pressure piston, which opens a connection channel between a piston interior and the rear space upon reaching a cut-off.
  • the object of the invention is to provide an electro-hydraulic pressing device, which is particularly suitable for the production of pipe connections by means of press fittings, which has a good efficiency both when opening and closing the press jaws.
  • the electrohydraulic pressing device has a pressure piston acting on pressing jaws.
  • the pressure piston can act on pressing jaws directly or through intermediary elements, such as a roller head.
  • intermediary elements such as a roller head.
  • an indirect action the pressing jaws ie a closing of the press loop done.
  • Such electro-hydraulic pressing devices are particularly suitable for the production of pipe connections by means of press fittings, but also for crimping cable lugs and the like.
  • the pressure piston is slidably disposed in a piston chamber, wherein the piston chamber is divided by the pressure piston in a pressure chamber and a rear space.
  • Hydraulic fluid can be pumped from a reservoir into the pressure chamber with the aid of a hydraulic pump.
  • a return spring is provided in the pressure chamber opposite the rear space arranged. This serves to push back the pressure piston in its initial position after pressing.
  • the pressure piston designed in particular as a needle valve pressure relief valve is arranged.
  • the pressure relief valve opens a connecting channel, which is arranged between the rear space and a piston interior.
  • the channel as well as in DE 20 2004 000 215 described, laterally past a valve piston of the pressure relief valve.
  • a balance piston is arranged in the piston interior.
  • the balance piston opens a connection opening to allow pushing back of the pressure piston after pressing into the starting position. Accordingly, the connection opening is closed by the balance piston when the pressure piston is moved from its initial position during the pressing operation.
  • the connection opening is arranged between the pressure chamber and the piston interior. Furthermore, the balance piston closes a return flow channel until reaching the cut-off pressure. Upon reaching the cut-off pressure, the balance piston is moved, whereby on the one hand the connection opening between the pressure chamber and Piston interior is opened and thereby also the return flow channel is opened.
  • the balance piston is thus arranged within the pressure piston and is moved together with the pressure piston during the compression process, during which no relative movement between the balance piston and the pressure piston takes place during the compression process. This takes place only when reaching the cut-off pressure. After reaching the cut-off pressure and thereby causing displacement of the balance piston of the pressure piston is pushed back by the return spring to its original position.
  • the fluid present in the pressure chamber flows through the connection opening into the return flow channel. Since the connecting channel is preferably arranged in the pressure piston, the fluid flows back through the pressure piston. Since the fluid flows directly into the pressure space during the compression process and no valve is arranged in the flow path, the pressing operation can be carried out by moving the pressure piston during the pressing operation with high efficiency.
  • the pushing back of the pressure piston with the return spring can be done with high efficiency, since the connection opening, which can be closed by the balance piston, must not be designed as a needle valve. As a result, problems with impurities are avoided or at least reduced.
  • the connecting piston which preferably has a relatively large cross section, is opened by the balance piston so that the working piston automatically returns to the rear end position or the starting position. This can be done very quickly due to the provision of a large cross-section of the connection opening.
  • a compression spring could be provided, which presses the balance piston in the direction of the connection opening during the Verpressvorvorgang for closing the same.
  • this spring can be omitted or at least be designed as a weak, purely supporting spring.
  • This is the piston interior is connected via a feed channel to the pressure chamber. Through this supply passage, fluid flows into the interior of the piston during the injection process onto the rear side of the balance piston and presses it into the connection opening or a valve seat surrounding the connection opening or against an edge of the connection opening. Since the supply channel is open during the entire injection process, the pressure on the back of the balance piston increases in accordance with the pressure rise in the pressure chamber. As a result, the balance piston is pressed ever more firmly against the connection opening. As a result, in spite of the increase in the pressure in the pressure chamber, a displacement of the balance piston caused thereby and thus opening of the connection opening is avoided.
  • a support of the holding of the balance piston in a closed position by a spring arranged on the back of the balance piston can be completely eliminated, in particular, if the back of the balance piston has a pressure surface whose pressure-relevant cross section is greater than the opening cross section of the connection opening.
  • the force acting on the rear side of the balance piston is greater than the force acting on a front side of the balance piston closing the connection opening.
  • the pressing device is located at the beginning of a Verpressvorgangs, ie, before the pressure piston starts to move, an end face of the pressure piston to a sealing seat of the piston chamber.
  • This is the end face of the piston in which the connection opening is arranged.
  • the sealing seat surrounds the connection opening. Since the supply of hydraulic fluid to the pressure chamber outside of this sealing seat takes place in this embodiment, thus initially no or at most a small force acts on the surface of the balance piston occluding the connection opening. Rather, the pressure is initially increased on the back of the balance piston, so that the Libra piston is pressed into the connection opening.
  • the pressure piston starts to move and thus pressure is also built up on a front side of the balance piston, the force built up on the back side of the balance piston is already higher, so that unintentional displacement of the balance piston and thus opening of the connection opening is avoided.
  • the pressure piston has a head element arranged in the pressure chamber.
  • the balance piston is arranged completely or at least partially within the head element.
  • the head element is designed such that it at least partially does not bear against the inside of the pressure chamber. This has the consequence that the hydraulic fluid flowing into the pressure chamber, in particular at the beginning of the injection process, can flow past the head element and initially flows via the feed channel into the chamber provided behind the scale piston in order to exert a corresponding force on the rear side of the balance piston.
  • the head element is cylindrical according to the pressure chamber and has a smaller diameter than the pressure chamber, so that between the inside of the pressure chamber and the head member, an annular gap is formed.
  • the return flow channel is arranged such that it connects the pressure chamber with the rear space with open balance piston.
  • the return flow channel is therefore preferably provided in the pressure piston. In this way, in particular a compact design can be realized. It is also advantageous to direct the fluid flowing back into the reservoir when the piston is pushed back into the rear space, since the rear space is preferably connected to the reservoir anyway. This is necessary because fluid, which is located in the back space, is pushed out of the back space of the piston during the injection process. This is done by a particular provided in the housing of the pressing tool return or channel that connects the back space with the reservoir.
  • the closed during the Verpressvorgangs of the pressure relief valve connecting channel is preferably arranged in a partition between the piston interior and a valve chamber.
  • the pressure relief valve is thus preferably arranged within the pressure piston.
  • the valve space is in this case that space in which the piston of the pressure relief valve is arranged.
  • opening the connecting channel by moving the piston of the pressure relief valve this is moved into the valve chamber.
  • the piston may have corresponding longitudinally extending grooves or channels or be arranged with a correspondingly large clearance or space in this space.
  • the pressure relief valve is in a preferred embodiment, a needle valve, so that a connecting channel can be provided with a small diameter. This is not detrimental here, since only small amounts of fluid have to flow through the connecting channel and, as a result, neither the efficiency is worsened nor the danger of blockage exists.
  • the balance piston has a pressure surface whose pressure-effective cross section is greater than the opening cross section of the connection opening. Due to this difference surface, the balance piston also remains in the closed position during an interruption of the pressing process.
  • FIG. 1 schematically the head portion of a forceps-like pressing tool is shown.
  • This has two pressing jaws 10, which are interconnected by a connecting element 12 and pivotable about bolts 14.
  • a connecting element 12 Depending on the configuration of the openings 16 on the two pressing jaws 10, compression of press fittings or other components can take place.
  • the recesses 16 or slightly differently shaped recesses can be used to connect them to the free end of the press loop and then to use the pressing tool to contract a press loop.
  • the closing of the pressing jaws 10 takes place with the aid of a particularly electrohydraulically driven pressure piston 18.
  • the pressure piston 18 is connected to a roller head 20.
  • the rollers of the roller head 20 come into contact with the flanks 24 of the pressing jaws 10, so that the in FIG. 1 left ends of the pressing jaws 10 are pressed apart. This results in a pivoting of the pressing jaws around the bolts 14 and thus closing the pressing jaws.
  • the pressing jaws 10 can be inserted into a housing 26 of the pressing tool and fixed by a retaining pin 28 in this.
  • the pressing jaws 10 are thus replaceable, so that different pressing jaws can be operated with the same pressing tool.
  • FIG. 2 the pressing tool is shown in longitudinal section, wherein the pressing jaws 10 are not inserted into the housing 26.
  • the piston 18 is arranged in a piston chamber 30, wherein the pressure piston 18 divides the piston chamber 30 in a pressure chamber 32 and a rear space 34.
  • the pressure chamber 32 is connected via a channel 36 with a hydraulic pump 38.
  • the hydraulic pump 38 delivers hydraulic fluid from a reservoir 40 through the channel 36 into the pressure chamber 32.
  • the hydraulic pump 38 is driven by means of a battery 42 and an intermediate gear 44.
  • the piston To divide the piston chamber 30 into the pressure chamber 32 and the pressure chamber 34, the piston has a plate-shaped projection 46, which is sealed in particular with the additional use of an annular sealing element 48 against an inner side 50 of the piston chamber 30.
  • about the channel 36 is a supply of fluid into the pressure chamber 32, so that the pressure increases therein and to carry out a pressing operation, the piston 18 from the in FIG. 3 shown initial position is moved to the right. After the conclusion of the pressing operation, the pressure piston 18 is moved back through a return spring 52 arranged in the rear space 34.
  • a designed as a needle valve pressure relief valve 54 is disposed in the interior of the piston 18.
  • a valve piston 56 of the pressure relief valve 54 has a needle 58 which closes a connecting channel 60, as long as the cut-off pressure has not yet been reached.
  • the closing of the connecting channel 60 by means of a compression spring 62, the bias can be adjusted by a screw 64.
  • a balance piston 68 is arranged inside a head element 66, which is part of the piston 18.
  • the balance piston 68 is displaceable in a piston interior 70.
  • the balance piston 60 closes a connection opening 72 and a return flow channel 74 arranged in the head element 66 and in the piston 18.
  • the head element 66 has a sealing seat 76 on an end face of the head element 66 arranged in the pressure space 32.
  • the sealing seat 76 cooperates with an annular projection 78 provided on the inner side 50 of the pressure chamber 32, so that a seal surrounding the connecting opening 32 is formed.
  • a feed channel 80 is provided through which fluid passes from the pressure chamber 32 into the piston interior 70.
  • the fluid passing through the feed channel 80 into the inner space 70 causes a pressure build-up in the inner space 70, which is on a rear side 82 of the balance piston 68 exerts a force by which the balance piston 68 closes the connection opening 72.
  • connection channel 60 of the pressure relief valve 54 is connected to the inner space 70.
  • the rear space 34 is connected in the illustrated embodiment via two returns 84 to the reservoir 40.
  • connection opening 72 since a pressure is already built up in the interior 70, this does not lead to the displacement of the balance piston 68 inwardly and thus not to open the connection opening 72. Further, since the effective pressure surface on the back of the balance piston 68 is greater than the cross section of the connection opening the force acting in the direction of the connection opening 72 is greater than the counterforce generated by the pressure in the pressure space 32, so that the connection opening 72 remains closed during the entire closing and pressing process.
  • the opening of the relief valve 54 causes a pressure drop in the piston interior 70. This reduces the force acting on the back 82, so that the now much higher, prevailing in the pressure chamber 32 pressure shifts the balance piston in the interior of the head member 66. As a result, the connection opening 72 as well as the remindströmkanale 74 is opened. Thus, hydraulic fluid can flow from the pressure chamber 32 into the back space 34 through the communication port 72 and the return flow passages 74 disposed in the head member 66 and the piston 18, respectively.
  • the pressing device is ready for the next pressing operation.
  • the position of the balance piston 68 may not yet correspond to that in FIG FIG. 3 position shown. However, this is ensured because at the beginning of the next injection process first hydraulic oil flows through the supply line 80 into the interior 70.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Press Drives And Press Lines (AREA)
  • Details Of Reciprocating Pumps (AREA)

Description

Die Erfindung betrifft ein elektrohydraulisches Pressgerät, insbesondere zum Herstellen von Rohrverbindungen mittels Pressfittings und zum Herstellen von Crimpverbindungen in der Elektrotechnik.The invention relates to an electro-hydraulic pressing device, in particular for producing pipe connections by means of press fittings and for producing crimp connections in electrical engineering.

Ein derartiges Pressgerät, wie es beispielsweise in DE 20 2004 000 215 U beschrieben ist, weist beispielsweise zwei zangenartig ausgebildete Pressbacken auf. Diese werden von einem elektrohydraulischen Antrieb betätigt. Hierzu ist in einem Kolbenraum ein Druckkolben vorgesehen, dessen Druckraum mit der Hydraulikpumpe verbunden ist. Hierbei wird durch Förderung von Fluid in den Druckraum der Druckkolben bewegt. Hierdurch erfolgt ein Schließen der Pressbacken, wobei der Druckkolben möglicherweise über einen Rollenkopf die Pressbacken betätigt. Ferner sind anstelle zangenartig ausgebildeter Pressgeräte auch sogenannte Pressschlingen bekannt. Diese weisen mehrere gelenkig miteinander verbundene Pressbacken auf, die beispielsweise um ein zu verpressendes Pressfitting herumgelegt werden. Die Öffnung der Pressschlinge wird mit einem Pressgerät verbunden, so dass durch Zusammenziehen der Pressschlinge ein Verpressen erfolgt. Das hierbei verwendete Pressgerät ist im Wesentlichen entsprechend dem in der DE 20 2004 000 215 U beschriebenen Pressgerät ausgebildet. Ferner sind auch Axial-Pressgeräte bekannt, bei denen ebenfalls der Druckaufbau elektrohydraulisch erfolgt, um einen Druckkolben zu verschieben.Such a pressing device, as for example in DE 20 2004 000 215 U is described, for example, has two pliers-like pressing jaws. These are actuated by an electro-hydraulic drive. For this purpose, a pressure piston is provided in a piston chamber, the pressure chamber is connected to the hydraulic pump. In this case, the pressure piston is moved by pumping fluid into the pressure chamber. As a result, the pressing jaws are closed, wherein the pressure piston possibly actuates the pressing jaws via a roller head. Furthermore, so-called press loops are also known pliers-like pressing devices known. These have a plurality of articulated pressing jaws, which are wrapped, for example, around a press fitting to be pressed. The opening of the press sling is connected to a pressing device, so that compression takes place by contraction of the press sling. The pressing device used in this case is essentially corresponding to that in the DE 20 2004 000 215 U formed pressing device described. Furthermore, axial compression devices are known in which also the pressure buildup is electro-hydraulic to move a pressure piston.

Zum Druckaufbau in dem Druckraum wird von der Hydraulikpumpe Hydraulikfluid in den Druckraum gefördert. Hierdurch erfolgt ein Bewegen des Druckkolbens und ein Durchführen der Verpressung. Bei zuverlässig durchgeführter Verpressung entsteht am Ende der Verpressung in dem Druckraum ein Abschaltdruck. Bei Erreichen des Abschaltdrucks erfolgt automatisch ein Beenden des Verpressvorgangs. Dies wird durch Vorsehen eines Überdruckventils in dem Druckkolben erzielt. Hierbei handelt es sich beispielsweise, wie in DE 20 2004 000 215 beschrieben um ein Nadelventil, das einen im Druckkolben vorgesehenen Verbindungskanal bei Erzielen des definierten Abschaltdrucks öffnet. Bei Erreichen des Abschaltdrucks wird der Kolben des Überdruckventils gegen die Kraft einer Vorspannfeder in den Druckkolben hineinverschoben, so dass das Fluid aus dem Druckraum durch den Verbindungskanal in einen sich dem Druckraum gegenüberliegenden Rückraum des Kolbenraums fließt. Hierbei strömt das Fluid seitlich an dem Kolben des Überdruckventils vorbei.To build up pressure in the pressure chamber, hydraulic fluid is delivered into the pressure chamber by the hydraulic pump. This results in a movement of the pressure piston and performing the compression. In reliably performed pressing creates a shut-off at the end of the compression in the pressure chamber. When the switch-off pressure is reached, the injection process is automatically stopped. This is achieved by providing a pressure relief valve in the pressure piston. These are, for example, as in DE 20 2004 000 215 described by a needle valve that opens a provided in the pressure piston connecting channel when achieving the defined cut-off pressure. Upon reaching the cut-off pressure of the piston of the pressure relief valve is moved against the force of a biasing spring into the pressure piston, so that the fluid flows from the pressure chamber through the connecting channel in a pressure chamber opposite the rear space of the piston chamber. In this case, the fluid flows laterally past the piston of the pressure relief valve.

In dem die Hydraulikpumpe mit dem Druckraum verbindenden Strömungskanal ist ferner ein Steuerventil vorgesehen. Bei Erreichen des Abschaltdrucks verringert sich aufgrund des Öffnens des Überdruckventils der Druck im Druckraum und somit auch in dem Verbindungskanal zwischen Hydraulikpumpe und Druckraum. Dies führt zum Schalten des Steuerventils, wodurch ein Rückströmkanal geöffnet wird. Der Rückströmkanal verbindet den Druckraum mit dem Fluidreservoir. Das Steuerventil ist hierbei in DE 20 2004 000 215 derart aufgebaut, dass während des Verpressvorgangs Fluid von der Hydraulikpumpe durch einen engen im Ventilkolben des Steuerventils vorgesehenen Kanal gepumpt wird. Bei Erreichen des Abschaltdrucks und somit Sinken des Drucks im Druckraum wird der federbelastete Ventilkolben des Steuerventils verschoben und gibt den Rückströmkanal frei. Das Zurückdrücken des Druckkolbens in die Ausgangsposition erfolgt durch eine im Druckraum angeordnete Rückstellfeder. Diese drückt beim Zurückstellen das in dem Druckraum vorhandene Fluid durch den vom Steuerventil frei gegebenen Rückströmkanal in das Reservoir. Nachteilig bei dem in der DE 20 2004 000 215 beschriebenen Pressgerät ist, dass zur Durchführung des Pressvorgangs das Hydraulikfluid von der Hydraulikpumpe durch die einen geringen Querschnitt aufweisende Öffnung im Steuerventil gepumpt werden muss. Dies beeinträchtigt den Wirkungsgrad. Des Weiteren sind Öffnungen mit geringem Querschnitt verschmutzungsanfällig.In the hydraulic pump connecting to the pressure chamber flow channel, a control valve is also provided. Upon reaching the cut-off pressure decreases due to the opening of the pressure relief valve, the pressure in the pressure chamber and thus also in the connecting channel between the hydraulic pump and the pressure chamber. This leads to switching of the control valve, whereby a return flow is opened. The return flow channel connects the pressure chamber with the fluid reservoir. The control valve is here in DE 20 2004 000 215 such that fluid is pumped from the hydraulic pump through a narrow channel provided in the valve piston of the control valve during the injection process. Upon reaching the cut-off pressure and thus decreasing the pressure in the pressure chamber, the spring-loaded valve piston of the control valve is displaced and releases the return flow channel. The pushing back of the pressure piston in the starting position is effected by a return spring disposed in the pressure chamber. This presses when resetting the fluid present in the pressure chamber through the control valve free given return flow into the reservoir. A disadvantage of the in the DE 20 2004 000 215 described pressing device is that in order to carry out the pressing operation, the hydraulic fluid from the hydraulic pump must be pumped through the small cross-section opening in the control valve. This affects the efficiency. Furthermore, openings with a small cross section are susceptible to contamination.

Ferner ist aus DE 198 25 160 ein elektrohydraulisches Pressgerät bekannt. Bei diesem ist im Rückströmkanal ein Nadelventil angeordnet. Dieses Nadelventil wird bei Erreichen des Abschaltdrucks geöffnet, so dass das Hydraulikfluid aus dem Druckraum mit Hilfe der Rückstellfeder in das Reservoir zurückgedrückt wird. Das im Rückströmkanal angeordnete Nadelventil weist einen mit der Ventilnadel während des Verpressvorgangs geschlossenen Kanal mit geringem Querschnitt auf. Da auch hier ein Kanal mit geringem Querschnitt vorgesehen ist, durch den das Fluid hindurchgepresst werden muss, ist der Wirkungsgrad des in DE 198 25 160 beschriebenen Pressgeräts beim Zurückdrücken des Druckkolbens gering. Ferner besteht auch hier der Nachteil, das der im Nadelventil vorgesehene Kanal mit geringem Querschnitt leicht verschmutzt.Furthermore, it is off DE 198 25 160 an electro-hydraulic pressing device known. In this, a needle valve is arranged in the return flow. This needle valve is opened upon reaching the cut-off, so that the hydraulic fluid is pushed back from the pressure chamber by means of the return spring in the reservoir. The needle valve arranged in the return flow channel has a channel with a small cross section which is closed with the valve needle during the pressing process. Since here too a channel is provided with a small cross-section, through which the fluid must be pressed through, the efficiency of the in DE 198 25 160 described pressing device when pushing back the pressure piston low. Furthermore, there is also the disadvantage that the channel provided in the needle valve slightly contaminates with a small cross section.

Desweiteren ist ein ähnliches elektrohydraulisches Pressgerät aus DE 20 2006 001 889 U1 bekannt. Dieses weist ebenfalls einen auf Pressbacken einwirkenden Druckkolben auf, durch den ein Kolbenraum in einen Druckraum und einen Rückraum unterteilt ist. Mittels einer Hydraulikpumpe wird Hydraulikfluid aus einem Reservoir in den Druckraum gefördert. Im Rückraum ist eine Rückstellfeder zum Zurückdrücken des Druckkolbens nach erfolgter Verpressung angeordnet. Desweiteren ist im Druckkolben ein Überdruckventil angeordnet, das bei Erreichen eines Abschaltdrucks einen Verbindungskanal zwischen einem Kolbeninnenraum und dem Rückraum öffnet.Furthermore, a similar electro-hydraulic pressing device is off DE 20 2006 001 889 U1 known. This also has a pressing jaw acting on the pressure piston, through which a piston chamber is divided into a pressure chamber and a rear space. By means of a hydraulic pump hydraulic fluid is conveyed from a reservoir into the pressure chamber. In the rear space, a return spring for pushing back the pressure piston is arranged after pressing. Furthermore, a pressure relief valve is arranged in the pressure piston, which opens a connection channel between a piston interior and the rear space upon reaching a cut-off.

Aufgabe der Erfindung ist es, ein elektrohydraulisches Pressgerät zu schaffen, das insbesondere zur Herstellung von Rohrverbindungen mittels Pressfittings geeignet ist, das sowohl beim Öffnen als auch Schließen der Pressbacken einen guten Wirkungsgrad aufweist.The object of the invention is to provide an electro-hydraulic pressing device, which is particularly suitable for the production of pipe connections by means of press fittings, which has a good efficiency both when opening and closing the press jaws.

Die Lösung der Aufgabe erfolgt erfindungsgemäß durch die Merkmale des Anspruchs 1.The object is achieved according to the invention by the features of claim 1.

Das erfindungsgemäße elektrohydraulische Pressgerät weist einen auf Pressbacken einwirkenden Druckkolben auf. Hierbei kann der Druckkolben unmittelbar oder durch zwischengeschaltete Elemente, wie einen Rollenkopf, auf Pressbacken einwirken. Auch kann durch ein mit einer Pressschlinge verbundenes Pressgerät über Zwischenelemente ein mittelbares Einwirken auf die Pressbacken, d.h. ein Schließen der Pressschlinge, erfolgen. Derartige elektrohydraulische Pressgeräte sind insbesondere zur Herstellung von Rohrverbindungen mittels Pressfittings, aber auch zum Verquetschen von Kabelschuhen und dergleichen geeignet.The electrohydraulic pressing device according to the invention has a pressure piston acting on pressing jaws. In this case, the pressure piston can act on pressing jaws directly or through intermediary elements, such as a roller head. Also, by an associated with a press sling pressing device via intermediate elements an indirect action the pressing jaws, ie a closing of the press loop done. Such electro-hydraulic pressing devices are particularly suitable for the production of pipe connections by means of press fittings, but also for crimping cable lugs and the like.

Der Druckkolben ist in einem Kolbenraum verschiebbar angeordnet, wobei der Kolbenraum durch den Druckkolben in einen Druckraum und einen Rückraum unterteilt ist. Mit Hilfe einer Hydraulikpumpe kann Hydraulikfluid aus einem Reservoir in den Druckraum gefördert werden. Hierdurch erfolgt das Bewegen des Druckkolbens, wobei der Druck in dem Druckraum bei fortschreitender Verpressung ansteigt. In dem dem Druckraum gegenüberliegend angeordneten Rückraum ist eine Rückstellfeder vorgesehen. Diese dient zum Zurückdrücken des Druckkolbens in seine Ausgangsstellung nach erfolgter Verpressung. In dem Druckkolben ist ein insbesondere als Nadelventil ausgebildetes Überdruckventil angeordnet. Bei Erreichen eines Arbeitsdrucks, der in dem Druckraum erzielt wird, wenn die Verpressung abgeschlossen ist, öffnet das Überdruckventil einen Verbindungskanal, der zwischen dem Rückraum und einem Kolbeninnenraum angeordnet ist. Hierbei kann der Kanal, wie auch in DE 20 2004 000 215 beschrieben, seitlich an einem Ventilkolben des Überdruckventils vorbeiführen.The pressure piston is slidably disposed in a piston chamber, wherein the piston chamber is divided by the pressure piston in a pressure chamber and a rear space. Hydraulic fluid can be pumped from a reservoir into the pressure chamber with the aid of a hydraulic pump. As a result, the moving of the pressure piston, wherein the pressure in the pressure chamber increases with progressive compression takes place. In the pressure chamber opposite the rear space arranged a return spring is provided. This serves to push back the pressure piston in its initial position after pressing. In the pressure piston designed in particular as a needle valve pressure relief valve is arranged. Upon reaching a working pressure, which is achieved in the pressure chamber when the compression is completed, the pressure relief valve opens a connecting channel, which is arranged between the rear space and a piston interior. Here, the channel, as well as in DE 20 2004 000 215 described, laterally past a valve piston of the pressure relief valve.

Erfindungsgemäß ist in dem Kolbeninnenraum ein Waagekolben angeordnet. Der Waagekolben öffnet eine Verbindungsöffnung, um ein Zurückdrücken des Druckkolbens nach dem Verpressen in die Ausgangsstellung zu ermöglichen. Dementsprechend ist die Verbindungsöffnung von dem Waagekolben verschlossen, wenn der Druckkolben aus seiner Ausgangsstellung während des Verpressvorgangs bewegt wird. Die Verbindungsöffnung ist zwischen dem Druckraum und dem Kolbeninnenraum angeordnet. Des Weiteren verschließt der Waagekolben bis zum Erreichen des Abschaltdrucks einen Rückströmkanal. Bei Erreichen des Abschaltdrucks erfolgt ein Bewegen des Waagekolbens, wodurch einerseits die Verbindungsöffnung zwischen Druckraum und Kolbeninnenraum geöffnet wird und hierdurch ferner auch der Rückströmkanal geöffnet wird.According to the invention, a balance piston is arranged in the piston interior. The balance piston opens a connection opening to allow pushing back of the pressure piston after pressing into the starting position. Accordingly, the connection opening is closed by the balance piston when the pressure piston is moved from its initial position during the pressing operation. The connection opening is arranged between the pressure chamber and the piston interior. Furthermore, the balance piston closes a return flow channel until reaching the cut-off pressure. Upon reaching the cut-off pressure, the balance piston is moved, whereby on the one hand the connection opening between the pressure chamber and Piston interior is opened and thereby also the return flow channel is opened.

Der Waagekolben ist somit innerhalb des Druckkolbens angeordnet und wird während des Verpressvorgangs zusammen mit dem Druckkolben bewegt, wobei während des Verpressvorgangs keine relative Bewegung zwischen dem Waagekolben und dem Druckkolben erfolgt. Diese erfolgt erst bei Erreichen des Abschaltdrucks. Nach Erreichen des Abschaltdrucks und des hierdurch bewirkten Verschiebens des Waagekolbens wird der Druckkolben durch die Rückstellfeder in seine Ausgangsposition zurückgedrückt. Hierbei strömt das im Druckraum vorhandene Fluid durch die Verbindungsöffnung in den Rückströmkanal. Da der Verbindungskanal vorzugsweise in dem Druckkolben angeordnet ist, erfolgt ein Zurückströmen des Fluids durch den Druckkolben hindurch. Da das Fluid während des Verpressvorgangs unmittelbar in den Druckraum einströmt und in dem Strömungsweg kein Ventil angeordnet ist, kann der Verpressvorgang durch das Bewegen des Druckkolbens während des Verpressvorgangs mit hohem Wirkungsgrad erfolgen. Auch das Zurückdrücken des Druckkolbens mit der Rückstellfeder kann mit hohem Wirkungsgrad erfolgen, da die Verbindungsöffnung, die durch den Waagekolben verschließbar ist, nicht als Nadelventil ausgestaltet sein muss. Hierdurch sind auch Probleme durch Verunreinigungen vermieden oder zumindest verringert. Bei Erreichen des Abschaltdrucks wird von dem Waagekolben die vorzugsweise einen verhältnismäßig großen Querschnitt aufweisende Verbindungsöffnung geöffnet, so dass der Arbeitskolben selbsttätig in die hintere Endlage bzw. die Ausgangslage zurückfährt. Dies kann aufgrund des Vorsehens eines großen Querschnitts der Verbindungsöffnung sehr schnell erfolgen.The balance piston is thus arranged within the pressure piston and is moved together with the pressure piston during the compression process, during which no relative movement between the balance piston and the pressure piston takes place during the compression process. This takes place only when reaching the cut-off pressure. After reaching the cut-off pressure and thereby causing displacement of the balance piston of the pressure piston is pushed back by the return spring to its original position. In this case, the fluid present in the pressure chamber flows through the connection opening into the return flow channel. Since the connecting channel is preferably arranged in the pressure piston, the fluid flows back through the pressure piston. Since the fluid flows directly into the pressure space during the compression process and no valve is arranged in the flow path, the pressing operation can be carried out by moving the pressure piston during the pressing operation with high efficiency. Also, the pushing back of the pressure piston with the return spring can be done with high efficiency, since the connection opening, which can be closed by the balance piston, must not be designed as a needle valve. As a result, problems with impurities are avoided or at least reduced. When the cut-off pressure is reached, the connecting piston, which preferably has a relatively large cross section, is opened by the balance piston so that the working piston automatically returns to the rear end position or the starting position. This can be done very quickly due to the provision of a large cross-section of the connection opening.

Auf der Rückseite des Waagekolbens könnte eine Druckfeder vorgesehen werden, die den Waagekolben während des Verpressvorgangs in Richtung der Verbindungsöffnung zum Verschließen derselben drückt. Bei einer besonders bevorzugten Weiterbildung der Erfindung kann diese Feder entfallen oder zumindest als schwache, rein unterstützende Feder ausgebildet sein. Hierzu ist der Kolbeninnenraum über einen Zuführkanal mit dem Druckraum verbunden. Durch diesen Zuführkanal strömt während des Verpressvorgangs Fluid in den Kolbeninnenraum auf die Rückseite des Waagekolbens und drückt diesen in die Verbindungsöffnung bzw. einen die Verbindungsöffnung umgebenden Ventilsitz oder gegen einen Rand der Verbindungsöffnung. Da der Zuführkanal während des gesamten Verpressvorgangs offen ist, steigt der Druck auf der Rückseite des Waagekolbens entsprechend dem Druckanstieg in dem Druckraum. Dies hat zur Folge, dass der Waagekolben immer fester gegen die Verbindungsöffnung gedrückt wird. Hierdurch ist trotz des Erhöhens des Drucks in dem Druckraum ein hierdurch hervorgerufenes Verschieben des Waagekolbens und somit Öffnen der Verbindungsöffnung vermieden.On the back of the balance piston, a compression spring could be provided, which presses the balance piston in the direction of the connection opening during the Verpressvorvorgang for closing the same. In a particularly preferred embodiment of the invention, this spring can be omitted or at least be designed as a weak, purely supporting spring. This is the piston interior is connected via a feed channel to the pressure chamber. Through this supply passage, fluid flows into the interior of the piston during the injection process onto the rear side of the balance piston and presses it into the connection opening or a valve seat surrounding the connection opening or against an edge of the connection opening. Since the supply channel is open during the entire injection process, the pressure on the back of the balance piston increases in accordance with the pressure rise in the pressure chamber. As a result, the balance piston is pressed ever more firmly against the connection opening. As a result, in spite of the increase in the pressure in the pressure chamber, a displacement of the balance piston caused thereby and thus opening of the connection opening is avoided.

Eine Unterstützung des Haltens des Waagekolbens in einer Verschlussstellung durch ein auf der Rückseite des Waagekolbens angeordnete Feder kann insbesondere dann vollständig entfallen, wenn die Rückseite des Waagekolbens eine Druckfläche aufweist, deren druckrelevanter Querschnitt größer als der Öffnungsquerschnitt der Verbindungsöffnung ist. Diese Ausgestaltung der Flächenverhältnisse hat zur Folge, dass die auf die Rückseite des Waagekolbens wirkende Kraft größer ist als die auf eine Vorderseite des die Verbindungsöffnung verschließende Waagekolbens wirkende Kraft.A support of the holding of the balance piston in a closed position by a spring arranged on the back of the balance piston can be completely eliminated, in particular, if the back of the balance piston has a pressure surface whose pressure-relevant cross section is greater than the opening cross section of the connection opening. As a result of this configuration of the area ratios, the force acting on the rear side of the balance piston is greater than the force acting on a front side of the balance piston closing the connection opening.

Bei einer weiteren bevorzugten Weiterbildung des erfindungsgemäßen Pressgeräts liegt zu Beginn eines Verpressvorgangs, d.h. bevor sich der Druckkolben anfängt zu bewegen, eine Stirnseite des Druckkolbens an einem Dichtsitz des Kolbenraums an. Hierbei handelt es sich um diejenige Stirnseite des Kolbens, in der die Verbindungsöffnung angeordnet ist. Der Dichtsitz umgibt die Verbindungsöffnung. Da das Zuführen des Hydraulikfluids zu dem Druckraum außerhalb dieses Dichtsitzes in dieser Ausführungsform erfolgt, wirkt somit zunächst keine oder allenfalls eine geringe Kraft auf die die Verbindungsöffnung verschließende Fläche des Waagekolbens. Vielmehr wird zunächst auf der Rückseite des Waagekolbens der Druck erhöht, so dass der Waagekolben in die Verbindungsöffnung gedrückt wird. Sobald sich der Druckkolben beginnt zu bewegen und somit auch auf einer Vorderseite des Waagekolbens Druck aufgebaut wird, ist die auf der Rückseite des Waagekolbens aufgebaute Kraft bereits höher, so dass ein ungewolltes Verschieben des Waagekolbens und damit Öffnen der Verbindungsöffnung vermieden ist.In a further preferred embodiment of the pressing device according to the invention is located at the beginning of a Verpressvorgangs, ie, before the pressure piston starts to move, an end face of the pressure piston to a sealing seat of the piston chamber. This is the end face of the piston in which the connection opening is arranged. The sealing seat surrounds the connection opening. Since the supply of hydraulic fluid to the pressure chamber outside of this sealing seat takes place in this embodiment, thus initially no or at most a small force acts on the surface of the balance piston occluding the connection opening. Rather, the pressure is initially increased on the back of the balance piston, so that the Libra piston is pressed into the connection opening. As soon as the pressure piston starts to move and thus pressure is also built up on a front side of the balance piston, the force built up on the back side of the balance piston is already higher, so that unintentional displacement of the balance piston and thus opening of the connection opening is avoided.

Des Weiteren ist es bevorzugt, dass der Druckkolben ein im Druckraum angeordnetes Kopfelement aufweist. Vorzugsweise ist der Waagekolben vollständig oder zumindest teilweise innerhalb des Kopfelements angeordnet. Das Kopfelement ist derart ausgebildet, dass es zumindest teilweise nicht an der Innenseite des Druckraums anliegt. Dies hat zur Folge, dass das in dem Druckraum einströmende Hydraulikfluid, insbesondere zu Beginn des Verpressvorgangs, an dem Kopfelement vorbeiströmen kann und zunächst über den Zuführkanal in die hinter dem Waagekolben vorgesehene Kammer strömt, um auf die Rückseite des Waagekolbens eine entsprechende Kraft auszuüben. Insbesondere ist das Kopfelement entsprechend dem Druckraum zylindrisch ausgebildet und weist einen geringeren Durchmesser als der Druckraum auf, so dass zwischen der Innenseite des Druckraums und dem Kopfelement ein ringförmiger Spalt ausgebildet ist.Furthermore, it is preferred that the pressure piston has a head element arranged in the pressure chamber. Preferably, the balance piston is arranged completely or at least partially within the head element. The head element is designed such that it at least partially does not bear against the inside of the pressure chamber. This has the consequence that the hydraulic fluid flowing into the pressure chamber, in particular at the beginning of the injection process, can flow past the head element and initially flows via the feed channel into the chamber provided behind the scale piston in order to exert a corresponding force on the rear side of the balance piston. In particular, the head element is cylindrical according to the pressure chamber and has a smaller diameter than the pressure chamber, so that between the inside of the pressure chamber and the head member, an annular gap is formed.

Vorzugsweise ist der Rückströmkanal derart angeordnet, dass er bei geöffnetem Waagekolben den Druckraum mit dem Rückraum verbindet. Der Rückströmkanal ist daher vorzugsweise in dem Druckkolben vorgesehen. Hierdurch kann insbesondere eine kompakte Bauweise realisiert werden. Auch ist es vorteilhaft, das beim Zurückdrücken des Kolbens in das Reservoir zurückströmende Fluid in den Rückraum zu leiten, da der Rückraum vorzugsweise ohnehin mit dem Reservoir verbunden ist. Dies ist erforderlich, da Fluid, das sich im Rückraum befindet, während des Verpressvorgangs aus dem Rückraum von dem Kolben herausgedrückt wird. Dies erfolgt durch einen insbesondere im Gehäuse des Presswerkzeugs vorgesehenen Rücklauf bzw. Kanal, der den Rückraum mit dem Reservoir verbindet.Preferably, the return flow channel is arranged such that it connects the pressure chamber with the rear space with open balance piston. The return flow channel is therefore preferably provided in the pressure piston. In this way, in particular a compact design can be realized. It is also advantageous to direct the fluid flowing back into the reservoir when the piston is pushed back into the rear space, since the rear space is preferably connected to the reservoir anyway. This is necessary because fluid, which is located in the back space, is pushed out of the back space of the piston during the injection process. This is done by a particular provided in the housing of the pressing tool return or channel that connects the back space with the reservoir.

Der während des Verpressvorgangs von dem Überdruckventil verschlossene Verbindungskanal ist vorzugsweise in einer Trennwand zwischen dem Kolbeninnenraum und einem Ventilraum angeordnet. Das Überdruckventil ist somit vorzugsweise innerhalb des Druckkolbens angeordnet. Der Ventilraum ist hierbei derjenige Raum, in dem der Kolben des Überdruckventils angeordnet ist. Bei Öffnen des Verbindungskanals durch Verschieben des Kolbens des Überdruckventils wird dieser in den Ventilraum verschoben. Hierdurch strömt zumindest eine geringe Menge an Fluid durch den Verbindungskanal in den Ventilraum und gelangt vorzugsweise aus dem Ventilraum in den Rückraum. Hierbei ist es bevorzugt, dass das Fluid seitlich an dem Kolben des Überdruckventils vorbeiströmt. Hierzu kann der Kolben entsprechende in Längsrichtung verlaufende Nuten oder Kanäle aufweisen oder mit einem entsprechend großen Spiel bzw. Zwischenraum in diesem Raum angeordnet sein. Zu berücksichtigen ist hierbei, dass es erfindungsgemäß ausreicht, dass bei Erreichen des Abschaltdrucks eine geringe Menge an Fluid durch den Verbindungskanal strömt, da hierdurch nur der Druck in dem Innenraum reduziert werden muss, so dass sich der Waagekolben bewegt und die Verbindungsöffnung geöffnet wird. Sobald die Verbindungsöffnung offen ist, erfolgt ein Zurückströmen des Mediums aus dem Druckraum über den Rückströmkanal und vorzugsweise durch den Rückraum in das Reservoir. Bei dem Überdruckventil handelt es sich in bevorzugter Ausführungsform um ein Nadelventil, so dass ein Verbindungskanal mit geringem Durchmesser vorgesehen werden kann. Dies ist hier nicht nachteilig, da durch den Verbindungskanal nur geringe Mengen an Fluid strömen müssen und insofern hierdurch weder der Wirkungsgrad verschlechtert wird noch die Gefahr von Verstopfungen besteht.The closed during the Verpressvorgangs of the pressure relief valve connecting channel is preferably arranged in a partition between the piston interior and a valve chamber. The pressure relief valve is thus preferably arranged within the pressure piston. The valve space is in this case that space in which the piston of the pressure relief valve is arranged. When opening the connecting channel by moving the piston of the pressure relief valve this is moved into the valve chamber. As a result, at least a small amount of fluid flows through the connecting channel into the valve chamber and preferably passes from the valve chamber into the rear chamber. In this case, it is preferable for the fluid to flow past the piston of the overpressure valve laterally. For this purpose, the piston may have corresponding longitudinally extending grooves or channels or be arranged with a correspondingly large clearance or space in this space. It should be noted that it is sufficient according to the invention that upon reaching the cut-off pressure, a small amount of fluid flows through the connecting channel, as this only the pressure in the interior must be reduced, so that the balance piston moves and the connection opening is opened. As soon as the connection opening is open, the medium flows back out of the pressure chamber via the return flow channel and preferably through the rear space into the reservoir. The pressure relief valve is in a preferred embodiment, a needle valve, so that a connecting channel can be provided with a small diameter. This is not detrimental here, since only small amounts of fluid have to flow through the connecting channel and, as a result, neither the efficiency is worsened nor the danger of blockage exists.

Ferner ist es bei dem erfindungsgemäßen Presswerkzeug aufgrund des Vorsehens des Waagekolbens möglich, die Hydraulikpumpe bzw. den die Hydraulikpumpe antreibenden Elektromotor auch während des Pressvorgangs abzuschalten. Der Arbeitskolben verbleibt hierbei an der jeweiligen Stelle, wobei sodann durch erneutes Einschalten der Hydraulikpumpe der Pressvorgang fortgesetzt werden kann. Es ist somit ein sogenannter "Tippbetrieb" möglich. Dies ist erfindungsgemäß dadurch möglich, da der Waagekolben eine Druckfläche aufweist, deren druckwirksamer Querschnitt größer als der Öffnungsquerschnitt der Verbindungsöffnung ist. Aufgrund dieser Differenzfläche verbleibt der Waagekolben auch während einer Unterbrechung des Pressvorgangs in geschlossener Stellung.Furthermore, it is possible in the pressing tool according to the invention due to the provision of the balance piston to turn off the hydraulic pump or the hydraulic motor driving the electric motor during the pressing operation. The working piston remains here at the respective point, wherein then by re-switching the hydraulic pump of the pressing process can be continued. It is thus a so-called "inching" possible. This is inventively possible because the balance piston has a pressure surface whose pressure-effective cross section is greater than the opening cross section of the connection opening. Due to this difference surface, the balance piston also remains in the closed position during an interruption of the pressing process.

Nachfolgend wird die Erfindung anhand einer bevorzugten Ausführungsform unter Bezugnahme auf die anliegenden Zeichnungen näher erläutert. Es zeigen:

Figur 1
eine schematische Draufsicht eines Presswerkzeugs,
Figur 2
ein schematischer Längsschnitt durch ein Presswerkzeug in bevorzugter Ausführungsform,
Figur 3
einen Ausschnitt des Druckkolbens im Längsschnitt zu Beginn eines Verpressvorgangs und
Figur 4
einen Ausschnitt des Druckkolbens im Längsschnitt bei Beendigung eines Verpressvorgangs.
The invention will be explained in more detail with reference to a preferred embodiment with reference to the accompanying drawings. Show it:
FIG. 1
a schematic plan view of a pressing tool,
FIG. 2
a schematic longitudinal section through a pressing tool in a preferred embodiment,
FIG. 3
a section of the plunger in longitudinal section at the beginning of a Verpressvorgangs and
FIG. 4
a section of the plunger in a longitudinal section at the end of a Verpressvorgangs.

In Figur 1 ist schematisch der Kopfbereich eines zangenartigen Presswerkzeugs dargestellt. Dieser weist zwei Pressbacken 10 auf, die durch ein Verbindungselement 12 miteinander verbunden und um Bolzen 14 schwenkbar sind. Je nach Ausgestaltung der Öffnungen 16 an den beiden Pressbacken 10 kann ein Verpressen von Pressfittings oder anderen Bauteilen erfolgen. Ebenso können die Ausnehmungen 16 oder geringfügig anders gestaltete Ausnehmungen genutzt werden, um diese mit dem freien Ende der Pressschlinge zu verbinden und sodann das Presswerkzeug zum Zusammenziehen einer Pressschlinge zu nutzen.In FIG. 1 schematically the head portion of a forceps-like pressing tool is shown. This has two pressing jaws 10, which are interconnected by a connecting element 12 and pivotable about bolts 14. Depending on the configuration of the openings 16 on the two pressing jaws 10, compression of press fittings or other components can take place. Similarly, the recesses 16 or slightly differently shaped recesses can be used to connect them to the free end of the press loop and then to use the pressing tool to contract a press loop.

Das Schließen der Pressbacken 10 erfolgt mit Hilfe eines insbesondere elektrohydraulisch angetriebenen Druckkolbens 18. Der Druckkolben 18 ist mit einem Rollenkopf 20 verbunden. Durch Verschieben des Druckkolbens 18 sowie des Rollenkopfes 20 in Richtung eines Pfeils 22 gelangen die Rollen des Rollenkopfes 20 in Anlage an die Flanken 24 der Pressbacken 10, so dass die in Figur 1 linken Enden der Pressbacken 10 auseinandergedrückt werden. Hierdurch erfolgt ein Schwenken der Pressbacken um die Bolzen 14 und somit ein Schließen der Pressbacken.The closing of the pressing jaws 10 takes place with the aid of a particularly electrohydraulically driven pressure piston 18. The pressure piston 18 is connected to a roller head 20. By moving the pressure piston 18 and the roller head 20 in the direction of an arrow 22, the rollers of the roller head 20 come into contact with the flanks 24 of the pressing jaws 10, so that the in FIG. 1 left ends of the pressing jaws 10 are pressed apart. This results in a pivoting of the pressing jaws around the bolts 14 and thus closing the pressing jaws.

Die Pressbacken 10 können in ein Gehäuse 26 des Presswerkzeugs eingesteckt und über einen Haltestift 28 in diesem fixiert werden. Die Pressbacken 10 sind somit auswechselbar, so dass mit demselben Presswerkzeug unterschiedliche Pressbacken betrieben werden können.The pressing jaws 10 can be inserted into a housing 26 of the pressing tool and fixed by a retaining pin 28 in this. The pressing jaws 10 are thus replaceable, so that different pressing jaws can be operated with the same pressing tool.

In Figur 2 ist das Presswerkzeug in Längsschnitt dargestellt, wobei die Pressbacken 10 nicht in das Gehäuse 26 eingesetzt sind. Der Kolben 18 ist in einem Kolbenraum 30 angeordnet, wobei der Druckkolben 18 den Kolbenraum 30 in einem Druckraum 32 sowie einen Rückraum 34 unterteilt. Der Druckraum 32 ist über einen Kanal 36 mit einer Hydraulikpumpe 38 verbunden. Die Hydraulikpumpe 38 fördert Hydraulikfluid aus einem Reservoir 40 durch den Kanal 36 in den Druckraum 32. Der Antrieb der Hydraulikpumpe 38 erfolgt mit Hilfe eines Akkus 42 sowie eines zwischengeschalteten Getriebes 44.In FIG. 2 the pressing tool is shown in longitudinal section, wherein the pressing jaws 10 are not inserted into the housing 26. The piston 18 is arranged in a piston chamber 30, wherein the pressure piston 18 divides the piston chamber 30 in a pressure chamber 32 and a rear space 34. The pressure chamber 32 is connected via a channel 36 with a hydraulic pump 38. The hydraulic pump 38 delivers hydraulic fluid from a reservoir 40 through the channel 36 into the pressure chamber 32. The hydraulic pump 38 is driven by means of a battery 42 and an intermediate gear 44.

Nachfolgend wird anhand der Figuren 3 und 4 der Bereich des in dem Kolbenraum 30 angeordneten Kolbens 18 näher erläutert.The following is based on the FIGS. 3 and 4 the region of the piston 18 arranged in the piston chamber 30 is explained in more detail.

Zur Unterteilung des Kolbenraums 30 in den Druckraum 32 sowie den Druckraum 34 weist der Kolben einen tellerförmigen Ansatz 46 auf, der insbesondere unter zusätzlicher Verwendung eines ringförmigen Dichtelements 48 gegenüber einer Innenseite 50 des Kolbenraums 30 abgedichtet ist. Über den Kanal 36 erfolgt eine Zufuhr von Fluid in den Druckraum 32, so dass sich der Druck hierin erhöht und zur Durchführung eines Pressvorgangs der Kolben 18 aus der in Figur 3 dargestellten Anfangsstellung nach rechts bewegt wird. Nach Abschluss des Verpressvorgangs erfolgt ein Zurückbewegen des Druckkolbens 18 durch eine in dem Rückraum 34 angeordnete Rückstellfeder 52.To divide the piston chamber 30 into the pressure chamber 32 and the pressure chamber 34, the piston has a plate-shaped projection 46, which is sealed in particular with the additional use of an annular sealing element 48 against an inner side 50 of the piston chamber 30. about the channel 36 is a supply of fluid into the pressure chamber 32, so that the pressure increases therein and to carry out a pressing operation, the piston 18 from the in FIG. 3 shown initial position is moved to the right. After the conclusion of the pressing operation, the pressure piston 18 is moved back through a return spring 52 arranged in the rear space 34.

Im dargestellten Ausführungsbeispiel ist im Inneren des Kolbens 18 ein als Nadelventil ausgebildetes Überdruckventil 54 angeordnet. Ein Ventilkolben 56 des Überdruckventils 54 weist eine Nadel 58 auf, die einen Verbindungskanal 60 verschließt, solange der Abschaltdruck noch nicht erreicht ist. Das Verschließen des Verbindungskanals 60 erfolgt mittels einer Druckfeder 62, deren Vorspannung durch ein Schraubelement 64 eingestellt werden kann.In the illustrated embodiment, a designed as a needle valve pressure relief valve 54 is disposed in the interior of the piston 18. A valve piston 56 of the pressure relief valve 54 has a needle 58 which closes a connecting channel 60, as long as the cut-off pressure has not yet been reached. The closing of the connecting channel 60 by means of a compression spring 62, the bias can be adjusted by a screw 64.

Im Inneren eines Kopfelements 66, das Teil des Kolbens 18 ist, ist ein Waagekolben 68 angeordnet. Der Waagekolben 68 ist in einem Kolbeninnenraum 70 verschiebbar. Zu Beginn des Verpressvorgangs sowie bis zum Erreichen des Abschaltdrucks verschließt der Waagekolben 60 eine Verbindungsöffnung 72 sowie einen im Kopfelement 66 und im Kolben 18 angeordneten Rückströmkanal 74.Inside a head element 66, which is part of the piston 18, a balance piston 68 is arranged. The balance piston 68 is displaceable in a piston interior 70. At the beginning of the injection process and until reaching the cut-off pressure, the balance piston 60 closes a connection opening 72 and a return flow channel 74 arranged in the head element 66 and in the piston 18.

Das Kopfelement 66 weist einen Dichtsitz 76 an einer im Druckraum 32 angeordneten Stirnseite des Kopfelements 66 auf. Der Dichtsitz 76 wirkt mit einem an der Innenseite 50 des Druckraums 32 vorgesehenen ringförmigen Ansatz 78 zusammen, so dass eine die Verbindungsöffnung 32 umgebende Dichtung ausgebildet ist.The head element 66 has a sealing seat 76 on an end face of the head element 66 arranged in the pressure space 32. The sealing seat 76 cooperates with an annular projection 78 provided on the inner side 50 of the pressure chamber 32, so that a seal surrounding the connecting opening 32 is formed.

Des Weiteren ist ein Zuführkanal 80 vorgesehen, durch den Fluid aus dem Druckraum 32 in den Kolbeninnenraum 70 gelangt. Das durch den Zuführkanal 80 in den Innenraum 70 gelangende Fluid bewirkt einen Druckaufbau im Innenraum 70, der auf eine Rückseite 82 des Waagekolbens 68 eine Kraft ausübt, durch die der Waagekolben 68 die Verbindungsöffnung 72 verschließt.Furthermore, a feed channel 80 is provided through which fluid passes from the pressure chamber 32 into the piston interior 70. The fluid passing through the feed channel 80 into the inner space 70 causes a pressure build-up in the inner space 70, which is on a rear side 82 of the balance piston 68 exerts a force by which the balance piston 68 closes the connection opening 72.

Des Weiteren ist der Verbindungskanal 60 des Überdruckventils 54 mit dem Innenraum 70 verbunden. Der Rückraum 34 ist im dargestellten Ausführungsbeispiel über zwei Rückläufe 84 mit dem Reservoir 40 verbunden.Furthermore, the connecting channel 60 of the pressure relief valve 54 is connected to the inner space 70. The rear space 34 is connected in the illustrated embodiment via two returns 84 to the reservoir 40.

Beim Starten des Verpressvorgangs wird Hydraulikfluid durch den Kanal 36 in den Druckraum 32 gepumpt. Hier gelangt es zunächst in den ringförmigen Spalt zwischen dem Kopfelement 66 und der Innenseite 50 des Druckraums 32. Aufgrund des Dichtsitzes 76, 78 gelangt zunächst kein oder nur geringe Mengen an Fluid in den Bereich der Verbindungsöffnung 72. Vielmehr gelangt Fluid zunächst durch den Zuführkanal 80 in den Innenraum 70, so dass auf der Rückseite 82 des Waagekolbens 68 Druck aufgebaut wird. Hierdurch erfolgt ein sicheres Verschließen der Verbindungsöffnung 72 durch den Waagekolben 68. Nun erfolgt ein Bewegen des Kolbens 18 in Figur 3 nach rechts. Hierbei löst sich der Dichtsitz 76, 78, so dass auch in dem Bereich der Verbindungsöffnung Fluid strömt. Da jedoch im Innenraum 70 bereits ein Druck aufgebaut ist, führt dies nicht zum Verschieben des Waagekolbens 68 nach innen und somit auch nicht zum Öffnen der Verbindungsöffnung 72. Da ferner die wirksame Druckfläche an der Rückseite des Waagekolbens 68 größer ist als der Querschnitt der Verbindungsöffnung ist die in Richtung Verbindungsöffnung 72 wirkende Kraft größer als die durch den Druck im Druckraum 32 erzeugte Gegenkraft, so dass während des gesamten Schließ-und Verpressvorgangs die Verbindungsöffnung 72 verschlossen bleibt.When starting the Verpressvorgangs hydraulic fluid is pumped through the channel 36 into the pressure chamber 32. Here, it firstly enters the annular gap between the head element 66 and the inner side 50 of the pressure chamber 32. Because of the sealing seat 76, 78, initially no or only small amounts of fluid enter the region of the connection opening 72. Rather, fluid first passes through the feed channel 80 into the interior space 70 so that 68 pressure is built up on the back 82 of the balance piston. This results in a secure closing of the connection opening 72 by the balance piston 68. Now takes place a movement of the piston 18 in FIG. 3 to the right. In this case, the sealing seat 76, 78 is released, so that fluid also flows in the area of the connection opening. However, since a pressure is already built up in the interior 70, this does not lead to the displacement of the balance piston 68 inwardly and thus not to open the connection opening 72. Further, since the effective pressure surface on the back of the balance piston 68 is greater than the cross section of the connection opening the force acting in the direction of the connection opening 72 is greater than the counterforce generated by the pressure in the pressure space 32, so that the connection opening 72 remains closed during the entire closing and pressing process.

Nach erfolgter Verpressung, d.h. sobald der Abschaltdruck im Druckraum 32 erreicht ist, erfolgt ein Verschieben des Ventilkolbens 56 des Überdruckventils 54, so dass die Nadel 58 aus dem Verbindungskanal 60 herausgezogen wird und diesen öffnet. Hierdurch strömt aus dem Kolbeninnenraum 70 eine geringe Menge an Fluid durch den Verbindungskanal 60 in einen Ventilraum 86, in dem der Kolben 56 des Überdruckventils 54 verschiebbar angeordnet ist. Das Fluid kann aus dem Raum 76 seitlich neben dem Kolben 56 vorbeiströmen und gelangt durch nicht dargestellte Querbohrungen in den Rückraum 34.After pressing, ie as soon as the cut-off pressure is reached in the pressure chamber 32, there is a displacement of the valve piston 56 of the pressure relief valve 54, so that the needle 58 is pulled out of the connecting channel 60 and opens it. As a result, a small amount of fluid flows out of the piston interior 70 through the connection channel 60 into a valve chamber 86, in which the piston 56 of the pressure relief valve 54 is displaceably arranged is. The fluid can flow past from the space 76 laterally adjacent to the piston 56 and passes through transverse bores, not shown, in the rear space 34th

Das Öffnen des Überdruckventils 54 bewirkt einen Druckabfall im Kolbeninnenraum 70. Hierdurch verringert sich die auf die Rückseite 82 wirkende Kraft, so dass der nunmehr deutlich höhere, im Druckraum 32 herrschende Druck den Waagekolben in das Innere des Kopfelements 66 verschiebt. Hierdurch wird die Verbindungsöffnung 72 sowie auch der Rückströmkanale 74 geöffnet. Somit kann Hydraulikfluid aus der Druckkammer 32 durch die Verbindungsöffnung 72 und die Rückströmkanäle 74, die in dem Kopfelement 66 bzw. im Kolben 18 angeordnet sind, in den Rückraum 34 strömen.The opening of the relief valve 54 causes a pressure drop in the piston interior 70. This reduces the force acting on the back 82, so that the now much higher, prevailing in the pressure chamber 32 pressure shifts the balance piston in the interior of the head member 66. As a result, the connection opening 72 as well as the Rückströmkanale 74 is opened. Thus, hydraulic fluid can flow from the pressure chamber 32 into the back space 34 through the communication port 72 and the return flow passages 74 disposed in the head member 66 and the piston 18, respectively.

Aufgrund des hierdurch in dem Druckraum 32 sinkenden Drucks wird der gesamte Kolben 18 von der Rückstellfeder 52 in Figur 4 nach links bewegt. Hierdurch wird das Fluid aus dem Rückraum 32 durch die Verbindungsöffnung 72, die Rückströmkanäle 74 in den Rückraum 34 gefördert.Due to the sinking thereby in the pressure chamber 32 pressure of the entire piston 18 of the return spring 52 in FIG. 4 moved to the left. As a result, the fluid is conveyed from the rear space 32 through the connection opening 72, the return flow channels 74 into the rear space 34.

Sobald der Kolben 18 sich in der in Figur 3 dargestellten Stellung befindet, ist das Pressgerät bereit für den nächsten Verpressvorgang. Die Lage des Waagekolbens 68 entspricht hierbei gegebenenfalls noch nicht der in Figur 3 dargestellten Stellung. Diese wird jedoch sicher gestellt, da zu Beginn des nächsten Verpressvorgangs zunächst Hydrauliköl durch die Zuführleitung 80 in den Innenraum 70 strömt.Once the piston 18 is in the in FIG. 3 shown position, the pressing device is ready for the next pressing operation. The position of the balance piston 68 may not yet correspond to that in FIG FIG. 3 position shown. However, this is ensured because at the beginning of the next injection process first hydraulic oil flows through the supply line 80 into the interior 70.

Während des Verpressvorgangs wird das sich im Rückraum 34 befindende Hydrauliköl sodann durch die Rückläufe 84 wieder in das Reservoir 40 gepresst.During the injection process, the hydraulic oil located in the rear space 34 is then pressed back into the reservoir 40 by the returns 84.

Claims (11)

  1. An electro-hydraulic pressing device, particularly for producing tube connections by means of press fittings, and crimp connections in electrical engineering, comprising
    a pressure piston (80) acting on press jaws (10), said pressure piston being arranged in a piston chamber (30) and dividing the piston chamber (30) into a pressure chamber (32) and a return chamber (34),
    a hydraulic pump (38) for conveying hydraulic fluid from a reservoir (40) into the pressure chamber (32),
    a return spring (52) arranged in the return chamber (34) for pushing back the pressure piston (18) after completion of the pressing operation, and
    an overpressure valve (54) arranged in the pressure piston (18), which is operative to open a connection channel (60) between a piston interior (70) and the return chamber (34) when a switch-off pressure has been reached,
    characterized in that
    a balance piston (68) arranged in the piston interior (70), which is operative to close a connection opening (72) between the piston interior (70) and the pressure chamber (32) as well as a return flow channel (74) until the switch-off pressure has been reached.
  2. The electro-hydraulic pressing device according to claim 1, characterized in that the piston interior (70) is connected via a supply channel (80) to the pressure chamber (32) so that, until the switch-off pressure has been reached, a rear side (82) of the balance piston (68) facing away from said connection opening (72) is subjected to a working pressure generated by the hydraulic pump (38).
  3. The electro-hydraulic pressing device according to claim 2, characterized in that a rear side (82) of the balance piston (68) comprises a pressing face whose pressure-effective cross section is larger than the opening cross section of the connection opening (72).
  4. The electro-hydraulic pressing device according to any one of claims 1 to 3, characterized in that, prior to a pressure build-up in the pressure chamber (32), an end face (76) of the pressure piston (18) arranged in the pressure chamber (32) is in abutment on a sealing seat (78) of the pressure chamber (32), said sealing seat (78) surrounding the connection opening (72).
  5. The electro-hydraulic pressing device according to any one of claims 1 to 4, characterized in that the pressure piston (18) comprises a head element (66) arranged in the pressure chamber (32), said head element being at least partially not in abutment on an inner side (50) of the pressure chamber (32).
  6. The electro-hydraulic pressing device according to any one of claims 1 to 5, characterized in that, in the opened state of the balance piston (68), the return flow channel (74) connects the pressure chamber (32) to the return chamber (34).
  7. The electro-hydraulic pressing device according to any one of claims 1 to 6, characterized in that the return chamber (34) is connected via a return duct (84) to the reservoir (40).
  8. The electro-hydraulic pressing device according to any one of claims 1 to 7, characterized in that the connection channel (60) is arranged in a separating wall between the piston interior (70) and a valve chamber (86).
  9. The electro-hydraulic pressing device according to claim 8, characterized in that a valve piston (56) of the overpressure valve (54) is displaceably arranged in the valve chamber (86).
  10. The electro-hydraulic pressing device according to any one of claims 1 to 9, characterized in that, when the switch-off pressure has been reached, the balance piston (68) will open the connection opening (72) and the pressure piston (18) will thereby be automatically returned.
  11. The electro-hydraulic pressing device according to any one of claims 1 to 10, characterized in that, also in case of an interruption of the conveyance of hydraulic fluid, the pressure piston will during the press operation remain unchanged in the current position.
EP20120778337 2011-12-17 2012-10-24 Electro-hydraulic pressing device Active EP2643125B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE201120109251 DE202011109251U1 (en) 2011-12-17 2011-12-17 Electrohydraulic pressing device
PCT/EP2012/071040 WO2013087279A1 (en) 2011-12-17 2012-10-24 Electro-hydraulic pressing device

Publications (2)

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EP2643125A1 EP2643125A1 (en) 2013-10-02
EP2643125B1 true EP2643125B1 (en) 2014-05-14

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EP20120778337 Active EP2643125B1 (en) 2011-12-17 2012-10-24 Electro-hydraulic pressing device

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US (1) US9216501B2 (en)
EP (1) EP2643125B1 (en)
AU (1) AU2012351079B2 (en)
DE (1) DE202011109251U1 (en)
WO (1) WO2013087279A1 (en)

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CN108746414A (en) * 2018-06-01 2018-11-06 怀宁县恒源再生科技有限公司 A kind of iron and steel casting bender

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DE202011109251U1 (en) 2011-12-17 2013-03-18 Novopress Gmbh Pressen Und Presswerkzeuge & Co. Kg Electrohydraulic pressing device
DE202015105803U1 (en) * 2015-11-02 2015-11-12 Fibro Gmbh hand Press
CN118060375B (en) * 2024-04-24 2024-06-21 成都彩堂钣金有限公司 Down-pressing type rapid bending device and bending method for special-shaped steel pipe

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DE10216213A1 (en) * 2002-04-10 2003-10-23 Klauke Gmbh Gustav Electro-hydraulic pressing device and method for operating the same
US5195354A (en) * 1989-03-31 1993-03-23 Japan Storage Battery Co., Ltd. Cam crank mechanism and motor driven hydraulic tool
DE19825160A1 (en) 1997-10-15 1999-04-22 Klauke Gmbh Gustav Hydraulic press device e.g. for connecting cable shoes to electrical cables or for riveting
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DE202011109251U1 (en) 2011-12-17 2013-03-18 Novopress Gmbh Pressen Und Presswerkzeuge & Co. Kg Electrohydraulic pressing device

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Publication number Priority date Publication date Assignee Title
CN108746414A (en) * 2018-06-01 2018-11-06 怀宁县恒源再生科技有限公司 A kind of iron and steel casting bender

Also Published As

Publication number Publication date
EP2643125A1 (en) 2013-10-02
US9216501B2 (en) 2015-12-22
US20150000369A1 (en) 2015-01-01
AU2012351079B2 (en) 2016-05-19
WO2013087279A1 (en) 2013-06-20
DE202011109251U1 (en) 2013-03-18
AU2012351079A1 (en) 2014-07-03

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