EP0771598A1 - Process for reducing the friction by hydraulic forming with internal high pressure and device for hydraulic forming - Google Patents

Process for reducing the friction by hydraulic forming with internal high pressure and device for hydraulic forming Download PDF

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Publication number
EP0771598A1
EP0771598A1 EP95117680A EP95117680A EP0771598A1 EP 0771598 A1 EP0771598 A1 EP 0771598A1 EP 95117680 A EP95117680 A EP 95117680A EP 95117680 A EP95117680 A EP 95117680A EP 0771598 A1 EP0771598 A1 EP 0771598A1
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EP
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Prior art keywords
pressure
workpiece
forming
tool
hydraulic forming
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EP95117680A
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German (de)
French (fr)
Inventor
E. Olszewski
R. Hansen
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Benteler Deustchland GmbH
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Benteler Deustchland GmbH
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Application filed by Benteler Deustchland GmbH filed Critical Benteler Deustchland GmbH
Priority to EP95117680A priority Critical patent/EP0771598A1/en
Publication of EP0771598A1 publication Critical patent/EP0771598A1/en
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21DWORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D26/00Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
    • B21D26/02Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure
    • B21D26/033Deforming tubular bodies
    • B21D26/047Mould construction
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21DWORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D37/00Tools as parts of machines covered by this subclass
    • B21D37/18Lubricating, e.g. lubricating tool and workpiece simultaneously

Definitions

  • the invention relates on the one hand to a method for reducing the friction between the outer surface of a workpiece to be formed by means of hydraulic internal pressure and the forming surface of a press tool and on the other hand to a device for the hydraulic forming of a tubular hollow body.
  • Hydraulic shaping by means of internal high pressure is used when forming at least partially hollow, metallic workpieces in presses.
  • the workpieces are usually tubular hollow bodies.
  • the method is characterized in that the optionally preformed workpiece is placed in a press tool which has the shape of the workpiece to be produced. The press tool is then closed. The front ends of the hollow body are then sealed and the workpiece is filled with a liquid, the workpiece being supplied with increasing pressure. Under the pressure of the liquid and at the same time pushing the front ends of the workpiece, the workpiece enters a plastic state. The wall sections of the workpiece then begin to deform and take on the shape predetermined by the press tool by the workpiece resting against the inner surfaces of the press tool.
  • the object of the invention is to expand the field of application of hydraulic forming by means of internal high pressure and to make it more efficient overall, the forming of longer workpieces in particular being simplified.
  • the invention further relates to a device for hydraulic forming, in which the frictional relationships between the workpiece and the tool are improved during the forming.
  • the procedural part of this object is achieved in that a lubricant is introduced at least in regions between the workpiece and the tool during the forming process with an adjustable pressure and is distributed along the contact surfaces of the workpiece and the tool.
  • This defined lubrication pressure can be specified in particular in the areas of the largest deformation.
  • the lubricant is expediently distributed over the entire surface of the tool or workpiece, so that the contact surfaces are provided with a uniform lubricating film. As a result, the forces required for the reloading operations are reduced. At the same time, the forces for deflecting the workpiece in the tool are reduced.
  • Another advantage is that the life of the tool is extended.
  • the invention enables a significantly simpler setting and control of the technological parameters in the course of the forming.
  • the force of the tool and the liquid pressure result in such a tension state that guarantees that a deformation takes place without bursting and that the formation of folds and overlaps is avoided. This ensures a high quality of the finished formed parts with reduced energy consumption.
  • the lubricant pressure can be controlled as a function of the forming pressure.
  • the fluid pressure in the workpiece is controlled in such a way that the entire length of the workpiece rests on the cavity of the press tool. Together with the axial forces acting on the end faces of the workpiece, the material flows into the contour of the press tool. At the same time, the internal pressure must prevent the formation of folds during axial feeding. In the course of the forming process, the pressure size is therefore regulated depending on the replenishment path of the forehead. Coupled with this, depending on the forming pressure, a defined lubrication pressure is built up statically and the lubricant is distributed along the contact surfaces of the workpiece and tool. The logical combination of forming pressure and lubricating pressure means that the most favorable, coordinated process parameters are available in each forming stage.
  • a further advantageous embodiment provides for the lubricant to be specified at a constant pressure. This simplifies it the control structure of a system, wherein the advantages according to the invention and described above are also realized.
  • a device According to this, at least one lubrication pocket is provided in the forming surface of the press tool, via which a static lubricating pressure can be built up between the hollow body to be deformed and the forming surface.
  • a lubrication pocket can already suffice for the specification of the lubrication pressure.
  • a plurality of lubrication pockets are advantageously arranged distributed in the forming surface. The dimensions and shape of the lubrication pockets are such that the desired contour of the deformed workpiece is not impaired.
  • the lubrication pockets are designed as a circumferential groove adapted to the die contour.
  • the lubricant can thus be distributed evenly along the forming surface of the press tool.
  • a supply line to the lubrication pocket is sufficient for the lubricant supply.
  • the device according to the invention ensures optimized frictional relationships between the workpiece and the tool during the deformation. This not only enables the shaping of longer workpieces that require larger re-feeding processes, but also the shaping of workpieces from materials with lower deformability. Accordingly, hollow bodies can also are successfully deformed from alloyed steels that are otherwise not or only partially suitable for hydraulic forming. Furthermore, the device according to the invention is characterized by a longer service life of the press tool.
  • FIG. 1 shows a technically schematic and not to scale the lower part 1 of a press tool 2, which is otherwise not shown in detail, in a top view.
  • the lower part 1 has a recess 3 which is adapted to the contour of the workpiece to be formed. Together with a recess which is matched to this, it forms a die for the workpiece to be produced in the upper part of the press tool 2 (not shown).
  • the die has the shape of the finished workpiece.
  • the lubrication pockets 5 are designed as grooves 6 adapted to the contour of the forming surface 4. Corresponding grooves are provided in the upper part of the press tool 2, so that circumferential lubrication pockets are formed.
  • the lubrication pockets 5 are supplied with lubricant via channels 7 integrated in the lower part 1.
  • a preformed tubular hollow body 8 is indicated in dashed lines in FIG. After this has been inserted into the lower part 1, the press tool 2 is closed. In the next phase the hollow body 8 is filled with a sealed end 9 with a liquid and subjected to an increasing pressure. The material of the hollow body 8 reaches a plastic state through controlled fluid pressure within the hollow body 8 with simultaneous axial pushing of the ends 9. Its wall rests on the forming surfaces of the die, creating the desired shape. Depending on the deformation, the length of the hollow body 8 is shortened.
  • the pushing process of the ends 9 is characterized by the arrows F. Basically, it does not have to be pushed on both sides.
  • a defined lubrication pressure is specified during the forming process and is controlled as a function of the forming pressure.
  • the lubrication pressure can also be specified constantly.
  • the lubrication pressure is built up statically at the locations specified by the lubrication pockets 5 and distributed along the contact surfaces 10, 11 in the gap Sp between the hollow body 8 to be deformed and the forming surface 4. This reduces the forces required for the feeding and deflection processes. This also enables a more precise coordination of the mutually influencing technological parameters during the forming process. Wrinkling or cracking is thus counteracted.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mounting, Exchange, And Manufacturing Of Dies (AREA)

Abstract

A hollow body is shaped by hydraulic forming and there is a method for friction reduction. A lubricant with an adjustable pressure is introduced during the deformation process between the workpiece (8) and the tool (2). The lubricant is distributed along the contact surfaces (10,11) of the workpiece and the tool. The lubricant pressure is controllable in relation to the deformation pressure. The lubricant pressure can also remain constant.

Description

Die Erfindung betrifft einerseits ein Verfahren zur Verminderung der Reibung zwischen der äußeren Oberfläche eines mittels hydraulischem Innendruck umzuformenden Werkstücks und der Umformfläche eines Pressenwerkzeugs und andererseits eine Vorrichtung zum hydraulischen Umformen eines rohrförmigen Hohlkörpers.The invention relates on the one hand to a method for reducing the friction between the outer surface of a workpiece to be formed by means of hydraulic internal pressure and the forming surface of a press tool and on the other hand to a device for the hydraulic forming of a tubular hollow body.

Die hydraulische Formgebung mittels Innenhochdruck wird beim Umformen mindestens teilweise hohler, metallischer Werkstücke in Pressen angewendet. Üblicherweise handelt es sich bei den Werkstücken um rohrförmige Hohlkörper. Das Verfahren ist dadurch gekennzeichnet, daß das gegebenenfalls vorgeformte Werkstück in ein Pressenwerkzeug gelegt wird, welches die Form des herzustellenden Werkstücks aufweist. Das Pressenwerkzeug wird dann geschlossen. Anschließend werden die Stirnenden des Hohlkörpers abgedichtet und das Werkstück mit einer Flüssigkeit gefüllt, wobei dem Werkstück ein sich steigender Druck zugeführt wird. Unter dem Druck der Flüssigkeit bei gleichzeitigem Nachschieben der Stirnenden des Werkstücks gelangt das Werkstück in einen plastischen Zustand. Die Wandabschnitte des Werkstücks beginnen sich dann zu verformen und nehmen dabei die durch das Pressenwerkzeug vorgegebene Form an, indem sich das Werkstück an die Innenflächen des Pressenwerkzeugs anlegt.Hydraulic shaping by means of internal high pressure is used when forming at least partially hollow, metallic workpieces in presses. The workpieces are usually tubular hollow bodies. The method is characterized in that the optionally preformed workpiece is placed in a press tool which has the shape of the workpiece to be produced. The press tool is then closed. The front ends of the hollow body are then sealed and the workpiece is filled with a liquid, the workpiece being supplied with increasing pressure. Under the pressure of the liquid and at the same time pushing the front ends of the workpiece, the workpiece enters a plastic state. The wall sections of the workpiece then begin to deform and take on the shape predetermined by the press tool by the workpiece resting against the inner surfaces of the press tool.

Wenn sich der Druck innerhalb des Werkstücks aufbaut, wird dessen gesamte Oberfläche der Umformung unterworfen. Die allgemeine plastische Umformung bewirkt, daß das Werkzeug praktisch an der Innenwandung des Werkzeugs haftet. Die Außenflächen des Werkstücks entwickeln dann bei der Berührung mit den Umformflächen des Werkzeugs eine starke Reibung. Diese hat zum einen einen beschleunigten Werkzeugverschleiß zur Folge. Zum anderen muß die Nachschiebekraft entsprechend vergrößert werden, die Grenze bilden dabei die mechanischen Werkstoffkennwerte. Desweiteren wird es dadurch schwieriger, den erforderlichen Flüssigkeitsdruck im Hohlraum des Werkstücks richtig einzustellen. Zu hoher Flüssigkeitsdruck kann jedoch zu Verdünnungen oder zur Bildung von Rissen in der Wand, unzureichender Druck hingegen oft zur Faltenbildung führen.When the pressure builds up inside the workpiece, its entire surface is subjected to the forming process. The general plastic deformation causes the tool to practically adhere to the inner wall of the tool. The outer surfaces of the workpiece then develop strong friction when they come into contact with the forming surfaces of the tool. On the one hand, this results in accelerated tool wear. On the other hand, the pushing force must be increased accordingly, the limit being the mechanical material parameters. Furthermore, this makes it more difficult to correctly set the required fluid pressure in the cavity of the workpiece. However, excessive fluid pressure can cause thinning or cracking of the wall, but insufficient pressure can often cause wrinkles.

Problemen dieser Art ist man bislang dadurch begegnet, daß Schmierstoffe vor dem Umformen auf die Oberflächen von Werkstück bzw. Werkzeug aufgetragen wurden. Hierbei kommen Schmierstoffe zum Einsatz, die widerstandsfähig gegen hohe spezifische Drücke sind. Dieses Vorgehen stößt jedoch an seine Grenze bei großen Umformvorgängen bzw. bei der Umformung von langen Bauteilen mit größeren Nachschiebevorgängen. Die große Oberflächenreibung zwischen dem Werkstück und dem Werkzeug führt dann zu hohen Nachschiebekräften. Hierdurch können die zulässigen Werkstoffbelastungen überschritten werden. Dies kann zu unerwünschtem Ausschuß führen. Die vorteilhafte Technik der Innenhochdruckumformung stößt damit an eine Verfahrensgrenze.Problems of this type have hitherto been countered by applying lubricants to the surfaces of the workpiece or tool before forming. Lubricants are used that are resistant to high specific pressures. However, this approach reaches its limits with large forming processes or with the forming of long components with larger reloading processes. The large surface friction between the workpiece and the tool then leads to high pushing forces. This can exceed the permissible material loads. This can lead to undesirable rejects. The advantageous technology of hydroforming thus reaches a process limit.

Hiervon ausgehend liegt der Erfindung die Aufgabe zugrunde, den Anwendungsbereich der hydraulischen Umformung mittels Innenhochdruck zu erweitern und insgesamt effizienter zu gestalten, wobei insbesondere die Umformung von längeren Werkstücken vereinfacht wird. Gegenstand der Erfindung ist weiterhin eine Vorrichtung zum hydraulischen Umformen, bei der die Reibungsverhältnisse zwischen dem Werkstück und dem Werkzeug bei der Umformung verbessert sind.Proceeding from this, the object of the invention is to expand the field of application of hydraulic forming by means of internal high pressure and to make it more efficient overall, the forming of longer workpieces in particular being simplified. The invention further relates to a device for hydraulic forming, in which the frictional relationships between the workpiece and the tool are improved during the forming.

Erfindungsgemäß wird der verfahrensmäßige Teil dieser Aufgabe nach Anspruch 1 dadurch gelöst, daß ein Schmiermittel während des Umformvorgangs mit einem einstellbaren Druck mindestens bereichsweise zwischen Werkstück und Werkzeug eingebracht und entlang der Kontaktflächen von Werkstück und Werkzeug verteilt wird.According to the invention, the procedural part of this object is achieved in that a lubricant is introduced at least in regions between the workpiece and the tool during the forming process with an adjustable pressure and is distributed along the contact surfaces of the workpiece and the tool.

Dieser definierte Schmierdruck kann insbesondere in den Bereichen der größten Umformung vorgegeben werden. Zweckmäßigerweise wird das Schmiermittel über die gesamte Werkzeug- bzw. Werkstückoberfläche verteilt, so daß die Kontaktflächen mit einem gleichmäßigen Schmierfilm versehen sind. Hierdurch werden die erforderlichen Kräfte für die Nachschiebevorgänge verringert. Gleichsam werden auch die Kräfte für Umlenkungen des Werkstücks im Werkzeug reduziert.This defined lubrication pressure can be specified in particular in the areas of the largest deformation. The lubricant is expediently distributed over the entire surface of the tool or workpiece, so that the contact surfaces are provided with a uniform lubricating film. As a result, the forces required for the reloading operations are reduced. At the same time, the forces for deflecting the workpiece in the tool are reduced.

Ein weiterer Vorteil ist, daß die Lebensdauer des Werkzeugs verlängert wird.Another advantage is that the life of the tool is extended.

Die Erfindung ermöglicht eine wesentlich einfachere Einstellung und Steuerung der technologischen Kenngrößen im Verlauf des Umformens. So wird in der Wand des umzuformenden Werkstücks durch die Kraftwirkung des Werkzeugs und des Flüssigkeitsdrucks ein solcher Spannungszustand erreicht, der garantiert, daß ein Umformen ohne ein Bersten erfolgt, und darüberhinaus das Entstehen von Falten und Überlappungen vermieden wird. Damit ist eine hohe Qualität der fertigen Umformstücke bei verringertem Energieverbrauch gewährleistet.The invention enables a significantly simpler setting and control of the technological parameters in the course of the forming. Thus, in the wall of the workpiece to be formed, the force of the tool and the liquid pressure result in such a tension state that guarantees that a deformation takes place without bursting and that the formation of folds and overlaps is avoided. This ensures a high quality of the finished formed parts with reduced energy consumption.

Nach den Merkmalen des Anspruchs 2 ist der Schmiermitteldruck in Abhängigkeit vom Umformdruck steuerbar.According to the features of claim 2, the lubricant pressure can be controlled as a function of the forming pressure.

Bei der Verformung wird der Flüssigkeitsdruck im Werkstück wird so gesteuert, daß das Werkstück in seiner ganzen Länge am Hohlraum des Pressenwerkzeugs anliegt. Zusammen mit den an den Stirnenden des Werkstücks wirkenden Axialkräften wird das Fließen des Werkstoffs in die Kontur des Pressenwerkzeugs bewirkt. Gleichzeitig muß der Innendruck das Entstehen von Falten beim axialen Nachschieben vermeiden. Im Verlauf des Umformens wird daher die Druckgröße in Abhängigkeit vom Nachschubweg der Stirnenden reguliert. Hieran gekoppelt wird in Abhängigkeit vom Umformdruck an vorgegebenen Stellen ein definierter Schmierdruck statisch aufgebaut und das Schmiermittel entlang der Kontaktflächen von Werkstück und Werkzeug verteilt. Die logische Verknüpfung von Umformdruck und Schmierdruck bewirkt, daß in jedem Umformstadium die jeweils günstigsten aufeinander abgestimmten Verfahrensparameter vorliegen.During the deformation, the fluid pressure in the workpiece is controlled in such a way that the entire length of the workpiece rests on the cavity of the press tool. Together with the axial forces acting on the end faces of the workpiece, the material flows into the contour of the press tool. At the same time, the internal pressure must prevent the formation of folds during axial feeding. In the course of the forming process, the pressure size is therefore regulated depending on the replenishment path of the forehead. Coupled with this, depending on the forming pressure, a defined lubrication pressure is built up statically and the lubricant is distributed along the contact surfaces of the workpiece and tool. The logical combination of forming pressure and lubricating pressure means that the most favorable, coordinated process parameters are available in each forming stage.

Da eine aktive Steuerung des Schmiermitteldrucks nicht grundsätzlich nötig ist, sieht eine weitere vorteilhafte Ausführungsform gemäß Anspruch 3 vor, das Schmiermittel mit einem konstanten Druck vorzugeben. Dies vereinfacht den steuerungsmäßigen Aufbau einer Anlage, wobei die erfindungsgemaßen und vorstehend beschriebenen Vorteile ebenfalls realisiert werden.Since active control of the lubricant pressure is not fundamentally necessary, a further advantageous embodiment provides for the lubricant to be specified at a constant pressure. This simplifies it the control structure of a system, wherein the advantages according to the invention and described above are also realized.

Der gegenständliche Teil der Aufgabe wird durch eine Vorrichtung nach Anspruch 4 gelöst. Danach ist in der Umformfläche des Pressenwerkzeugs wenigstens eine Schmiertasche vorgesehen, über die ein statischer Schmierdruck zwischen dem zu verformenden Hohlkörper und der Umformfläche aufbaubar ist.The objective part of the task is solved by a device according to claim 4. According to this, at least one lubrication pocket is provided in the forming surface of the press tool, via which a static lubricating pressure can be built up between the hollow body to be deformed and the forming surface.

Grundsätzlich kann bereits eine Schmiertasche für die Schmierdruckvorgabe ausreichen. In Abhängigkeit von der Größe und Form des zu verformenden Hohlkörpers sind jedoch vorteilhaft mehrere Schmiertaschen in der Umformfläche verteilt angeordnet. Die Schmiertaschen sind in ihren Abmessungen und ihrer Form so ausgebildet, daß die gewünschte Kontur des verformten Werkstücks nicht beeinträchtigt wird.In principle, a lubrication pocket can already suffice for the specification of the lubrication pressure. Depending on the size and shape of the hollow body to be deformed, however, a plurality of lubrication pockets are advantageously arranged distributed in the forming surface. The dimensions and shape of the lubrication pockets are such that the desired contour of the deformed workpiece is not impaired.

Auch wenn unterschiedliche Konfigurationen der Schmiertaschen denkbar sind, wird eine besonders vorteilhafte Ausbildung darin gesehen, die Schmiertaschen als an die Gesenkkontur angepaßte umlaufende Nut auszubilden. Das Schmiermittel kann so gleichmäßig entlang der Umformfläche des Pressenwerkzeugs verteilt werden. Für die Schmiermittelversorgung genügt jeweils eine Zuleitung zur Schmiertasche.Even if different configurations of the lubrication pockets are conceivable, a particularly advantageous embodiment is seen in designing the lubrication pockets as a circumferential groove adapted to the die contour. The lubricant can thus be distributed evenly along the forming surface of the press tool. A supply line to the lubrication pocket is sufficient for the lubricant supply.

Die erfindungsgemäße Vorrichtung gewährleistet optimierte Reibungsverhältnisse zwischen Werkstück und Werkzeug bei der Verformung. Damit wird nicht nur die Umformung von längeren Werkstücken ermöglicht, bei denen größeren Nachschiebevorgänge erforderlich sind, sondern auch das Umformen von Werkstücken aus Werkstoffen mit niedrigerer Verformbarkeit. Dementsprechend können auch Hohlkörper aus legierten Stählen erfolgreich verformt werden, die ansonsten nicht oder nur bedingt für eine hydraulische Umformung geeignet sind. Weiterhin zeichnet sich die erfindungsgemäße Vorrichtung durch eine höhere Lebensdauer des Pressenwerkzeugs aus.The device according to the invention ensures optimized frictional relationships between the workpiece and the tool during the deformation. This not only enables the shaping of longer workpieces that require larger re-feeding processes, but also the shaping of workpieces from materials with lower deformability. Accordingly, hollow bodies can also are successfully deformed from alloyed steels that are otherwise not or only partially suitable for hydraulic forming. Furthermore, the device according to the invention is characterized by a longer service life of the press tool.

Die Erfindung ist nachfolgend anhand eines in der Zeichnung dargestellten Ausführungsbeispiels näher beschrieben.The invention is described below with reference to an embodiment shown in the drawing.

Die Figur 1 zeigt technisch schematisiert und nicht maßstäblich das Unterteil 1 eines ansonsten nicht näher dargestellten Pressenwerkzeugs 2 in der Draufsicht.FIG. 1 shows a technically schematic and not to scale the lower part 1 of a press tool 2, which is otherwise not shown in detail, in a top view.

Das Unterteil 1 verfügt über eine an die Kontur des zu formenden Werkstücks angepaßte Ausnehmung 3. Diese bildet zusammen mit einer hierauf abgestimmten Ausnehmung im nicht dargestellten Oberteil des Pressenwerkzeugs 2 eine Matrize für das herzustellende Werkstück. Die Matrize hat die Form des fertigen Werkstücks.The lower part 1 has a recess 3 which is adapted to the contour of the workpiece to be formed. Together with a recess which is matched to this, it forms a die for the workpiece to be produced in the upper part of the press tool 2 (not shown). The die has the shape of the finished workpiece.

Weiterhin erkennt man, daß in der Umformfläche 4 der Ausnehmung 3 Schmiertaschen 5 vorgesehen sind. Diese sind hier zur besseren Verdeutlichung vergrößert dargestellt.Furthermore, it can be seen that 3 lubrication pockets 5 are provided in the forming surface 4 of the recess. These are shown enlarged for clarity.

Die Schmiertaschen 5 sind als an die Kontur der Umformfläche 4 angepaßte Nuten 6 ausgebildet. Im Oberteil des Pressenwerkzeugs 2 sind korrespondierende Nuten vorgesehen, so daß umlaufende Schmiertaschen entstehen. Über im Unterteil 1 integrierte Kanäle 7 werden die Schmiertaschen 5 mit Schmiermittel versorgt.The lubrication pockets 5 are designed as grooves 6 adapted to the contour of the forming surface 4. Corresponding grooves are provided in the upper part of the press tool 2, so that circumferential lubrication pockets are formed. The lubrication pockets 5 are supplied with lubricant via channels 7 integrated in the lower part 1.

In gestrichelter Linienführung ist in der Figur 1 ein vorgeformter rohrförmiger Hohlkörper 8 angedeutet. Nachdem dieser in das Unterteil 1 eingelegt worden ist, wird das Pressenwerkzeug 2 geschlossen. In der nächsten Phase wird der Hohlkörper 8 bei abgedichteten Stirnenden 9 mit einer Flüssigkeit gefüllt und mit einem steigenden Druck beaufschlagt. Durch gesteuerten Flüssigkeitsdruck innerhalb des Hohlkörpers 8 bei gleichzeitigem axialen Nachschieben der Stirnenden 9 erreicht der Werkstoff des Hohlkörpers 8 einen plastischen Zustand. Seine Wandung legt sich an die Umformflächen der Matrize an, wodurch das gewünschte Formstück entsteht. In Abhängigkeit zur Umformung ergibt sich eine Längenkürzung des Hohlkörpers 8.A preformed tubular hollow body 8 is indicated in dashed lines in FIG. After this has been inserted into the lower part 1, the press tool 2 is closed. In the next phase the hollow body 8 is filled with a sealed end 9 with a liquid and subjected to an increasing pressure. The material of the hollow body 8 reaches a plastic state through controlled fluid pressure within the hollow body 8 with simultaneous axial pushing of the ends 9. Its wall rests on the forming surfaces of the die, creating the desired shape. Depending on the deformation, the length of the hollow body 8 is shortened.

Der Nachschiebevorgang der Stirnenden 9 ist durch die Pfeile F charakterisiert. Grundsätzlich muß das Nachschieben nicht beidseitig erfolgen.The pushing process of the ends 9 is characterized by the arrows F. Basically, it does not have to be pushed on both sides.

Während des Umformvorgangs wird ein definierter Schmierdruck vorgegeben, der in Abhängigkeit vom Umformdruck gesteuert wird. Der Schmierdruck kann aber auch konstant vorgegeben werden.A defined lubrication pressure is specified during the forming process and is controlled as a function of the forming pressure. The lubrication pressure can also be specified constantly.

Der Schmierdruck wird an den durch die Schmiertaschen 5 vorgegebenen Stellen statisch aufgebaut und entlang der Kontaktflächen 10, 11 im Spalt Sp zwischen dem zu verformenden Hohlkörper 8 und der Umformfläche 4 verteilt. Hierdurch werden die erforderlichen Kräfte für die Nachschiebe- und Umlenkvorgänge reduziert. Damit ist auch eine präzisere Abstimmung der sich gegenseitig beeinflussenden technologischen Kenngrößen bei der Umformung möglich. Einer Falten- oder Rißbildung wird so entgegengewirkt.The lubrication pressure is built up statically at the locations specified by the lubrication pockets 5 and distributed along the contact surfaces 10, 11 in the gap Sp between the hollow body 8 to be deformed and the forming surface 4. This reduces the forces required for the feeding and deflection processes. This also enables a more precise coordination of the mutually influencing technological parameters during the forming process. Wrinkling or cracking is thus counteracted.

BezugszeichenaufstellungList of reference symbols

11
- Unterteil- lower part
22nd
- Pressenwerkzeug- press tool
33rd
- Ausnehmung- recess
44th
- Umformfläche- forming surface
55
- Schmiertaschen- lubrication pockets
66
- Nut- groove
77
- Kanal- Channel
88th
- Hohlkörper- hollow body
99
- Stirnenden v. 7- forehead v. 7
1010th
- Kontaktfläche- contact area
1111
- Kontaktfläche- contact area
FF
- Pfeil- arrow
SpSp
- Spalt- gap

Claims (4)

Verfahren zur Verminderung der Reibung zwischen der äußeren Oberfläche eines mittels hydraulischem Innenhochdruck umzuformenden Werkstücks (8) und der Umformfläche (4) eines Pressenwerkzeugs (2), dadurch gekennzeichnet, daß ein Schmiermittel während des Umformvorgangs mit einem einstellbaren Druck mindestens bereichsweise zwischen Werkstück (8) und Werkzeug (2) eingebracht und entlang der Kontaktflächen (10, 11) von Werkstück (8) und Werkzeug (2) verteilt wird.Method for reducing the friction between the outer surface of a workpiece (8) to be formed by means of high hydraulic pressure and the forming surface (4) of a press tool (2), characterized in that a lubricant with an adjustable pressure at least in regions between the workpiece (8) during the forming process and tool (2) is introduced and distributed along the contact surfaces (10, 11) of workpiece (8) and tool (2). Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß der Druck in Abhängigkeit vom Umformdruck steuerbar ist.Method according to claim 1, characterized in that the pressure can be controlled as a function of the forming pressure. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß der Druck konstant vorgebbar ist.A method according to claim 1, characterized in that the pressure is constant. Vorrichtung zum hydraulischen Umformen eines rohrförmigen Hohlkörpers (8) mit einem geteilten Pressenwerkzeug (2), dadurch gekennzeichnet, daß in der Umformfläche (4) des Pressenwerkzeugs (2) wenigstens eine Schmiertasche (5) vorgesehen ist, über die ein statischer Schmierdruck zwischen dem Hohlkörper (8) und der Umformfläche (4) aufbaubar ist.Device for the hydraulic forming of a tubular hollow body (8) with a divided press tool (2), characterized in that at least one lubrication pocket (5) is provided in the forming surface (4) of the press tool (2), via which a static lubricating pressure between the hollow body (8) and the forming surface (4) can be built.
EP95117680A 1995-11-09 1995-11-09 Process for reducing the friction by hydraulic forming with internal high pressure and device for hydraulic forming Pending EP0771598A1 (en)

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EP95117680A EP0771598A1 (en) 1995-11-09 1995-11-09 Process for reducing the friction by hydraulic forming with internal high pressure and device for hydraulic forming

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EP95117680A EP0771598A1 (en) 1995-11-09 1995-11-09 Process for reducing the friction by hydraulic forming with internal high pressure and device for hydraulic forming

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1197273A1 (en) * 2000-10-10 2002-04-17 Sidmar N.V. An apparatus and method to perform hydroforming, hydromechanical forming or mechanical forming
WO2005092534A1 (en) * 2004-03-20 2005-10-06 Amborn, Peter Method for shaping a metallic hollow body in a shaping tool at an elevated temperature and a certain internal pressure
DE10357341B4 (en) * 2003-12-09 2006-02-09 Daimlerchrysler Ag Apparatus and method for hydroforming a blank
CN103551472A (en) * 2013-10-25 2014-02-05 南京航空航天大学 Push-bending forming process for hollow blade
CN112496138A (en) * 2020-11-09 2021-03-16 保隆(安徽)汽车配件有限公司 Internal high-pressure forming die and forming method of workpiece
CN118143114A (en) * 2024-05-09 2024-06-07 南通大岛康晟科技有限公司 Integrated forming device and forming process for high-pressure tee joint machining
CN118143114B (en) * 2024-05-09 2024-07-02 南通大岛康晟科技有限公司 Integrated forming device and forming process for high-pressure tee joint machining

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DE2440725A1 (en) * 1974-08-24 1976-03-11 Berg Kg Tube cold forming appliance - sectional forming mould, with apertures, sealed pressure tight
EP0512131A2 (en) * 1989-06-19 1992-11-11 Aluminum Company Of America Apparatus and method for lubricating and cooling in a draw and iron press
EP0562609A1 (en) * 1992-03-26 1993-09-29 S + S ELECTRONIC GmbH & Co. KG Spray lubricating appliance for automatic punching machines

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1197273A1 (en) * 2000-10-10 2002-04-17 Sidmar N.V. An apparatus and method to perform hydroforming, hydromechanical forming or mechanical forming
DE10357341B4 (en) * 2003-12-09 2006-02-09 Daimlerchrysler Ag Apparatus and method for hydroforming a blank
WO2005092534A1 (en) * 2004-03-20 2005-10-06 Amborn, Peter Method for shaping a metallic hollow body in a shaping tool at an elevated temperature and a certain internal pressure
US7810367B2 (en) 2004-03-20 2010-10-12 Karl Kipry Method of shaping a metallic hollow member in a shaping tool at increased temperature and under internal pressure
CN103551472A (en) * 2013-10-25 2014-02-05 南京航空航天大学 Push-bending forming process for hollow blade
CN103551472B (en) * 2013-10-25 2015-09-09 南京航空航天大学 A kind of hollow blade pushes away o ing technique
CN112496138A (en) * 2020-11-09 2021-03-16 保隆(安徽)汽车配件有限公司 Internal high-pressure forming die and forming method of workpiece
CN118143114A (en) * 2024-05-09 2024-06-07 南通大岛康晟科技有限公司 Integrated forming device and forming process for high-pressure tee joint machining
CN118143114B (en) * 2024-05-09 2024-07-02 南通大岛康晟科技有限公司 Integrated forming device and forming process for high-pressure tee joint machining

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