EP1446245B1 - Method and device for reshaping tubes - Google Patents

Method and device for reshaping tubes Download PDF

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Publication number
EP1446245B1
EP1446245B1 EP02787390A EP02787390A EP1446245B1 EP 1446245 B1 EP1446245 B1 EP 1446245B1 EP 02787390 A EP02787390 A EP 02787390A EP 02787390 A EP02787390 A EP 02787390A EP 1446245 B1 EP1446245 B1 EP 1446245B1
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EP
European Patent Office
Prior art keywords
tube
pressure
wall thickness
length
external diameter
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EP02787390A
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German (de)
French (fr)
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EP1446245A1 (en
Inventor
Luca Schulz
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Wilhelm Schulz GmbH
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Wilhelm Schulz GmbH
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Priority claimed from DE10241641A external-priority patent/DE10241641A1/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D39/00—Application of procedures in order to connect objects or parts, e.g. coating with sheet metal otherwise than by plating; Tube expanders
    • B21D39/08—Tube expanders
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D26/00—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
    • B21D26/02—Shaping 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
    • B21D26/033—Deforming tubular bodies
    • B21D26/041—Means for controlling fluid parameters, e.g. pressure or temperature
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D26/00—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
    • B21D26/02—Shaping 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
    • B21D26/033—Deforming tubular bodies
    • B21D26/043—Means for controlling the axial pusher
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49805—Shaping by direct application of fluent pressure

Definitions

  • the present invention relates to a method for forming tubes and to an apparatus for carrying out the method.
  • the present invention has for its object to provide a method by which pipes of different outer diameter and with different wall thicknesses are easy to produce. This includes the provision of the device for carrying out the method.
  • the core of the invention is a targeted matching of the internal pressure P H and the axial pressure P M as a function of the required wall thickness and the outside diameter, taking into account the material type of the tube to be formed.
  • the invention has the advantage that pipes with a relatively large diameter / wall thickness ratio can be produced, which withstand high compressive stresses with minimal wall thickness , By cold forming by means of hydroforming hollow profiles are obtained, which meet high quality requirements and make additional quality checks unnecessary. This results from the fact that the pressure test during the forming has already taken place in principle.
  • the production times with the method according to the invention are considerably shorter compared to conventional methods for producing, for example, pipes with a larger diameter.
  • Another advantage is that even pipes made of relatively expensive materials with less material can be produced are as hitherto, because of the increased strength properties caused by the work hardening during forming or the narrower tolerable wall thickness tolerances, the tubes can now be formed relatively thin even with large diameters at constant load requirements, such as the maximum allowable voltages.
  • a particular advantage of the method according to the invention is that special customer requirements in terms of outer diameter and wall thickness can be easily and easily met by appropriately tuning the forming conditions, without the need for costly and expensive conversions.
  • the degree of deformation can be chosen such that a microstructure transformation leading to cold hardening occurs.
  • the plunger act only on the end surfaces of these facing pipe ends. This is essentially a free deformation of the clamped tube, ie, no die is used, as was used in the conventional method. This essentially also applies if no outer diameter increase is to take place, that is, only the wall thickness is to be increased. This is only initially a small support of the wall, because the thicker the wall, the more sufficient is the intrinsic strength.
  • the change in the axial distance of the plunger from each other can be done by shifting one or both plunger.
  • the size ratios of the outer diameter before and after the hydroforming are at a ratio of more than 1: 1.5 and in the respective material-dependent limits of up to 1: 3 of the output to the final diameter.
  • pipes with a large diameter can be produced from tubes or hollow profiles with relatively small diameters.
  • the process is inexpensive and easier to carry out than the conventional manufacturing processes such as e.g. rolling or hot forming for large diameter pipes.
  • Large diameters are ranges of outside diameters from 219 mm to over 1000 mm.
  • the respective process parameters particularly the spent internal pressure P H, the applied axial pressure P M and the axial path are respectively stored the plunger depending on the material and the geometry of serving as starting part pipe piece or of the finished pipe obtained.
  • These stored data can serve as reference values when making specific customer requests, ie special pipes, and can be continuously supplemented by parameters obtained. The quality and manufacturing reliability is increased or a production scrap is considerably reduced.
  • a centering device is provided, by means of which the tube to be clamped can be aligned with respect to the pressure punches.
  • sealing elements are provided on the ends of the plunger, which seal the transition to the ends of the clamped tube.
  • a support can be introduced, which defines the outer dimension of the tube to be formed.
  • This support may consist of several shell-shaped, together forming a closed shape segments.
  • the wall thicknesses are very close to the minimum wall thickness for example required by regulations BeiastungsPark. Rules may be standards, such as the ISO, EN or DIN standards for pipes. Since by means of the control device of the pressing process targeted to the final result, ie the hollow profile geometry of the tube to be produced adjustable, precision tubes can be produced in a very simple and time-saving manner
  • strain hardening can be achieved during the forming, and this is done by the structural transformation of the material caused by the stretching and stretching.
  • a tube produced in this way has a uniform, fine microstructure compared to the pipes produced by conventional methods - not treated. This finer microstructure leads to improved strength values combined with very low deadweight deviations. It is essential that all of this is achieved in the single process step, that is, the forming, and thus no further - costly - heat treatment is required.
  • the strength values of the pipe are generally increased, in particular the yield strength and the tensile strength, which is why such a pipe has higher strength properties compared to the hollow profiles produced by hot forming process with relatively thin wall thickness.
  • the hollow profile at a current wall thickness at or slightly above the mathematical minimum wall thickness is significantly below that of precision tubes, in particular with less than 5 percent tolerance deviation of the minimum wall thickness of the hollow profile to be produced for a wall thickness corresponding to the required pressure resistance.
  • the small dimensional deviation saves material compared to tubes produced by conventional methods, which is advantageous in particular for special materials and cost-intensive metal alloys or for application-related weight problems.
  • a pressing device according to the invention is shown schematically in a sectional view, in which a serving as a starting part pipe piece 1 is arranged with an initial diameter D A inside a pressing tool 2, which consists of a tool upper part 3 and a tool lower part is composed.
  • the tool halves are each provided on a machine bed 5 and a pressing device 6 acting from above, which keep the two-part mold 3, 4 closed during the expansion of the pipe section 1 by means of internal high pressure, each side plunger 7, 8 are provided, which on the one hand the front ends of the Pipe piece 1 for application of the hydraulic high pressure P H seal and on the other hand are provided to act on the pipe 1 with a mechanical axial pressure P M.
  • a central through hole 9 is provided for supplying a hydraulic pressure means of a pressure generating device, not shown in Fig. 1 in the interior of the pipe section 1.
  • the two tool halves 3, 4, the upper die 3 and the lower tool part 4 have a uniform Inner shape, according to the produced end diameter D E of the pipe section 1 and are interchangeable mounted on the device.
  • the upper tool part 3 is mounted on the upper punch 10, whereas the lower tool part 4 is mounted replaceably on the machine bed 5.
  • the metal tube 11 is massively deformed after application of the method according to the invention up to the inner surface of the upper tool part 3 and the tool rear part 4, d, h, wherein a desired wall thickness d E of the pipe section 11 to be produced deviates less than 5 percent of the minimum wall thickness to be produced.
  • the vote of the hydraulic high pressure P H and the mechanical axial pressures P M of the lateral plunger 7, 8 and the axial path a of the plunger takes place in such a way that exactly the wall thickness d E of the metal tube to be produced despite the illustrated embodiment about 2 times the diameter increase can be produced.
  • According to the required wall thickness d E and the degree of expansion of the produced tube 11 is shortened relative to the output pipe piece 1. In this way, precision tubes with a large diameter and only very small wall thickness can be produced in a single and surprisingly simple production step.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Shaping Metal By Deep-Drawing, Or The Like (AREA)
  • Forging (AREA)
  • Shaping Of Tube Ends By Bending Or Straightening (AREA)
  • Lining Or Joining Of Plastics Or The Like (AREA)

Abstract

A method and an apparatus for reshaping a tube having an initial outside diameter, an initial wall thickness, and an initial length to form a tube have a reshaped outside diameter, a reshaped length, and a reshaped wall thickness, wherein at least one of the reshaped outside diameter, the reshaped length, and the reshaped wall thickness is different than a respective one of the initial outside diameter, the initial wall thickness, and the initial length. The method includes mounting the tube between two axially displaceable pressure rams with the ends of the tube against respective rams; applying an internal hydraulic pressure to the tube; applying an axial mechanical pressure to the tube via the rams; and simultaneously and uniformly cold-working the tube over its entire length by adjusting the internal hydraulic pressure and the axial mechanical pressure as a function of the reshaped outside diameter, the reshaped wall thickness, and the reshaped length.

Description

Die vorliegende Erfindung betrifft ein Verfahren zum Umformen von Rohren sowie eine Vorrichtung zur Durchführung des Verfahrens.The present invention relates to a method for forming tubes and to an apparatus for carrying out the method.

Zur Herstellung von Rohren, insbesondere mit einem verhältnismäßig großen Rohrdurchmesser, ist es bekannt, aus gewalzten Blechen oder Bändem Schlitzrohre zu formen und diese dann an den Längskanten zu verschweißen. Derartige Stahlrohre sind für sehr hohe Drücke geeignet und weisen eine relativ große Genauigkeit hinsichtlich ihrer Wanddicken und Oberflächenbeschaffenheit auf. Sie finden Verwendung in speziellen Anwendungsgebieten, welche hohe Belastungsgrenzen erfordern, wie zum Beispiel in Kraftwerken oder in der Petrochemie. Nachteilig ist bei diesem Verfahren, dass die Präzisionsherstellung der Rohre durch Maßwatzen äußerst zeitaufwendig und somit kostenintensiv ist.For the production of pipes, in particular with a relatively large pipe diameter, it is known to form slit pipes from rolled sheets or strips and then to weld them to the longitudinal edges. Such steel tubes are suitable for very high pressures and have a relatively high accuracy in terms of their wall thicknesses and surface finish. They are used in special fields of application which require high load limits, such as in power plants or in the petrochemical industry. A disadvantage of this method is that the precision production of the tubes by Maßwatzen extremely time consuming and thus costly.

Es ist des Weiteren bekannt, mit dem Innenhochdruckumform-Verfahren aus einem als Ausgangsteil dienenden Rohrstück komplexe Hohlbauteile einer gewünschten Bauteilgeometrie durch Kaltumformen ohne Wärmebehandlung herzustellen. In der Regel wird hierfür ein äußeres Formwerkzeug mit der gewünschten Bauteilgeometrie entsprechender Innenform verwendet, welche bei gleichzeitiger Beaufschlagung des Rohrstücks mit einem hohen hydraulischen Innendruck das Rohrstück in die gewünschte Form bringt.
Dieses auch als "Hydroforming" bezeichnete Verfahren wird beispielsweise zur Herstellung von komplexen Hohlbauteilen verwendet, wie Gehäusen für Rohrleitungsarmaturen, wie es in der veröffentlichten intemationalen Patentanmeldung WO 99/52659 beschrieben ist.It is also known to produce complex hollow components of a desired component geometry by cold forming without heat treatment using the hydroforming method from a pipe section serving as a starting part. In general, this is an external mold with the desired component geometry corresponding inner mold is used, which brings the pipe section in the desired shape with simultaneous application of pressure to the pipe section with a high hydraulic internal pressure.
This process, also referred to as "hydroforming", is used, for example, for the production of complex hollow components, such as housings for pipeline fittings, as described in published international patent application WO 99/52659.

Es ist weiterhin aus der DE-AS 1 081 856 bekannt, relativ dünnwandige Rohre durch einen hydraulischen Innendruck leicht aufzuweiten zum Zweck des Kalibrierens der Rohre, wobei ein äußeres Formgebungswerkzeug bestehend aus einer Reihe von längsgeteilten Hülsen verwendet wird, die eine Formgebungs-Matrize bilden, welche das Rohr während des Dehnungsvorgangs dicht umschließt Die Herstellung von aufgeweiteten Rohren erfordert bei diesem bekannten Verfahren aufwändige Betätigungsmechanismen für jedes Paar von Hülsenhälften der Formgebungsmatrize. Außerdem ist mit diesem Verfahren eine Aufweitung von Rohrdurchmessem nur in eingeschränktem Maße durchführbar, wie es das Kalibrieren relativ dünnwandiger Rohrstücke erfordert. Ein Herstellen von Rohren mit deutlich größerem Durchmesser ist nicht möglich.It is also known from DE-AS 1 081 856 to slightly expand relatively thin-walled tubes by an internal hydraulic pressure for the purpose of calibrating the tubes, using an external forming tool consisting of a series of longitudinally divided sleeves forming a forming die, which tightly encloses the tube during the stretching process expanded tubes in this known method requires elaborate actuating mechanisms for each pair of sleeve halves of the forming die. In addition, with this method, an expansion of pipe diameters can only be carried out to a limited extent, as it requires the calibration of relatively thin-walled pipe sections. Producing pipes with a much larger diameter is not possible.

Aus der US-A-4 364 251 ist ein Verfahren zum Umformen eines zwischen zwei axial verschiebbaren Druckstempeln eingespannten Rohres, das einen Ausgangsaußendurchmesser, eine Ausgangswandstärke und eine Ausgangslänge aufweist, bekannt, wobei mittels eines in dessen Innerem erzeugbaren hydraulischen Druckes, ein Fertigrohr erzeugt wird, mit einem - gegenüber dem Ausgangsrohr - anderem Außendurchmesser, anderer Länge und anderer Wandstärke, und zwar durch gleichzeitige und gleichmäßige Kaltverformung über seine gesamte Länge.
Dabei wird ein axialer Anpressdruck der Stempel gegen die Rohrenden aufgebracht, der aber nur den Zweck hat, die dichtende Anlage der Stempel an den Rohrenden sicher zu stellen.From US-A-4 364 251 a method is known for forming a tube clamped between two axially displaceable plungers having an outlet outside diameter, an outlet wall thickness and an outlet length, wherein a finished tube is produced by means of a hydraulic pressure which can be generated in the interior thereof , with a different outside diameter, different length and wall thickness from the starting tube, by simultaneous and uniform cold working over its entire length.
In this case, an axial contact pressure of the stamp is applied against the pipe ends, but only has the purpose to make sure the sealing contact the punch at the pipe ends.

Der vorliegenden Erfindung liegt die Aufgabe zugrunde, ein Verfahren zu schaffen, mit dem Rohre unterschiedlichster Außendurchmesser sowie mit verschiedensten Wandstärken einfach herstellbar sind. Hierzu gehört auch die Bereitstellung der Vorrichtung zur Durchführung des Verfahrens.The present invention has for its object to provide a method by which pipes of different outer diameter and with different wall thicknesses are easy to produce. This includes the provision of the device for carrying out the method.

Diese Aufgabe wird erfindungsgemäß durch ein Verfahren mit den Schritten gemäß Anspruch 1 sowie eine Vorrichtung mit den Merkmalen des Anspruchs 10 gelöst. Vorteilhafte Ausgestaltungen und Weiterbildungen sind Gegenstand der jeweiligen Unteransprüche.This object is achieved by a method with the steps according to claim 1 and an apparatus having the features of claim 10. Advantageous embodiments and further developments are the subject of the respective subclaims.

Im Einzelnen betrifft die Erfindung ein Verfahren zum Umformen eines zwischen zwei axial verschiebbaren Druckstempein eingespannten Rohres , das einen Ausgangsaußendurchmesser, eine Ausgangswandstärke und eine Ausgangslänge aufweist, mittels eines in dessen Innerem erzeugbaren hydraulischen Druckes, zu einem Fertigrohr mit - gegenüber dem Ausgangsrohr - anderem Außendurchmesser oder anderer Länge und/oder anderer Wandstärke,
wobei
das Ausgangsrohr gleichzeitig und gleichmäßig über seine gesamte Länge kalt verformt wird und die Höhe des hydraulischen Innendruckes, des mechanischen Axialdruckes, die axiale Verschiebung der Druckstempel sowie deren auf die Rohrenden einwirkender Anpressdruck derart aufeinander abgestimmt werden, dass es

  • bei einer Erhöhung des hydraulischen Innendruckes und Beibehaltung des axialen Abstandes der Druckstempel zu einer Vergrößerung des Außendurchmessers bei gleichzeitiger Verringerung der Wandstärke,
  • bei einer Erhöhung des hydraulischen Innendruckes und mittels des mechanischen Axialdruckes herbeigeführter Verringerung des axialen Abstandes der Druckstempel voneinander zu einer Vergrößerung des Außendurchmessers, Beibehaltung der Wandstärke und Verringerung der
    Rohrlänge
    und
  • bei einer Aufrechterhaltung eines hydraulischen Innendruckes, einer mittels des mechanischen Axialdruckes herbeigeführten Verringerung des axialen Abstandes der Druckstempel voneinander und einer Beibehaltung des Ausgangsaußendurchmessers des Rohres zu einer Verringerung der Rohrlänge und Vergrößerung der Wandstärke kommt.
In particular, the invention relates to a method for forming a clamped between two axially displaceable Druckstempein tube having an output outer diameter, an output wall thickness and an output length, by means of a producible in its interior hydraulic pressure, to a finished tube - compared to the output tube - other outer diameter or other length and / or other wall thickness,
in which
the output tube is simultaneously cold and uniformly deformed over its entire length and the height of the hydraulic internal pressure, the mechanical axial pressure, the axial displacement of the plunger and their force acting on the pipe ends contact pressure are coordinated such that it
  • with an increase in the internal hydraulic pressure and maintaining the axial distance of the plunger to increase the outer diameter while reducing the wall thickness,
  • with an increase in the hydraulic internal pressure and by means of the mechanical thrust induced reduction in the axial distance of the plunger from each other to increase the outer diameter, maintaining the wall thickness and reducing the
    tube length
    and
  • while maintaining a hydraulic internal pressure, a reduction of the axial distance of the plungers from each other caused by the mechanical thrust and a maintenance of the Ausgangsausßendurchmessers of the tube to a reduction in the tube length and increasing the wall thickness comes.

Kern der Erfindung ist ein gezieltes aufeinander Abstimmen des Innendrucks PH und des Axialdruckes PM in Abhängigkeit von der geforderten Wandstärke und dem Außendurchmesser unter Berücksichtigung der Materialart des umzuformenden Rohres. Gegenüber den bisherigen Verfahren zur Herstellung von Hohlprofilen, insbesondere von Rohren eines großen Durchmessers, wie das Warmumformen oder das Präzisionswalzen, hat die Erfindung den Vorteil, dass Rohre mit relativ großem Durchmesser /Wandstärken-Verhältnis herstellbar sind, welche auch hohen Druckbeanspruchungen bei minimaler Wandstärke standhalten. Durch das Kaltumformen mittels Innenhochdruck werden Hohlprofile erhalten, die hohen Qualitätsanforderungen genügen und zusätzliche Qualitätsüberprüfungen überflüssig machen. Dies ergibt sich daraus, dass die Druckprüfung bei der Umformung im Prinzip schon stattgefunden hat. Zudem sind die Herstellungszeiten mit dem erfindungsgemäßen Verfahren erheblich kürzer gegenüber herkömmlichen Verfahren zur Herstellung von beispielsweise Rohren mit größerem Durchmesser. Ein weiterer Vorteil besteht darin, dass auch Rohre aus relativ teuren Materialien mit einem geringeren Materialaufwand herstellbar sind als bisher, da durch die erhöhten Festigkeitseigenschaften, hervorgerufen durch die Kaltverfestigung bei der Umformung bzw. die enger einhaltbaren Wandstärketoleranzen, die Rohre auch bei großen Durchmessern nun relativ dünnwandig ausgebildet sein können bei gleichbleibenden Belastungsanforderungen, wie z.B. den maximal zulässigen Spannungen.The core of the invention is a targeted matching of the internal pressure P H and the axial pressure P M as a function of the required wall thickness and the outside diameter, taking into account the material type of the tube to be formed. Compared to the previous method for the production of hollow sections, in particular of pipes of a large diameter, such as hot forming or precision rolling, the invention has the advantage that pipes with a relatively large diameter / wall thickness ratio can be produced, which withstand high compressive stresses with minimal wall thickness , By cold forming by means of hydroforming hollow profiles are obtained, which meet high quality requirements and make additional quality checks unnecessary. This results from the fact that the pressure test during the forming has already taken place in principle. In addition, the production times with the method according to the invention are considerably shorter compared to conventional methods for producing, for example, pipes with a larger diameter. Another advantage is that even pipes made of relatively expensive materials with less material can be produced are as hitherto, because of the increased strength properties caused by the work hardening during forming or the narrower tolerable wall thickness tolerances, the tubes can now be formed relatively thin even with large diameters at constant load requirements, such as the maximum allowable voltages.

Ein besonderer Vorteil des erfindungsgemäßen Verfahren liegt darin, dass spezielle Kundenwünsche hinsichtlich Außendurchmesser und Wandstärke einfach und problemlos durch entsprechendes Abstimmen der Umformbedingungen erfüllt werden können, ohne das es aufwendiger und teurer Umrüstungen bedarf.A particular advantage of the method according to the invention is that special customer requirements in terms of outer diameter and wall thickness can be easily and easily met by appropriately tuning the forming conditions, without the need for costly and expensive conversions.

Wichtig für die Umformung selbst ist, dass diese vom Ausgangsrohr zum Fertigrohr kontinuierlich und mit konstanter Geschwindigkeit erfolgt.It is important for the forming itself that this takes place from the starting tube to the finished tube continuously and at constant speed.

Hierbei kann der Grad der Umformung materialabhängig so gewählt werden, dass eine zur Kaltvertestigung führende Gefügeumwandlung eintritt.Depending on the material, the degree of deformation can be chosen such that a microstructure transformation leading to cold hardening occurs.

Um die verschiedensten Außendurchmesser, Wandstärken und letztlich Rohrlängen erreichen zu können, bedarf es der Abstimmung der einzelnen Umformbedingungen. Hierzu gehören die axiale Verschiebung der Druckstempel und die Veränderung des Innendruckes im umzuformenden Rohr. Dabei muss beispeilsweise auch berücksichtigt werden, dass während der Vergrößerung des Außendurchmessers des Rohres der Innendruck verringert und der Anpressdruck der Druckstempel an die Rohrenden angepasst wird.In order to be able to achieve a wide variety of outside diameters, wall thicknesses and ultimately tube lengths, it is necessary to coordinate the individual forming conditions. These include the axial displacement of the plunger and the change in internal pressure in the tube to be formed. It must also be taken into account, for example, that during the enlargement of the outer diameter of the tube, the internal pressure is reduced and the contact pressure of the pressure ram is adapted to the tube ends.

Für das Verfahren ist es weiterhin von Bedeutung, dass die Druckstempel nur auf die Stimflächen der diesen zugewandten Rohrenden einwirken. Damit erfolgt im wesentlichen eine freie Verformung des eingespannten Rohres, d.h. es wird kein Gesenk benutzt, wie es bei den herkömmlichen Verfahren angewandt wurde.
Dies gilt im wesentlichen auch dann, wenn keine Außendurchmesservergrößerung erfolgen soll, also nur die Wandstärke zu erhöhen ist. Hierbei erfolgt nur anfänglich eine geringe Abstützung der Wand, denn je dicker die Wand wird, desto mehr reicht die Eigenfestigkeit aus.For the method, it is also important that the plunger act only on the end surfaces of these facing pipe ends. This is essentially a free deformation of the clamped tube, ie, no die is used, as was used in the conventional method.
This essentially also applies if no outer diameter increase is to take place, that is, only the wall thickness is to be increased. This is only initially a small support of the wall, because the thicker the wall, the more sufficient is the intrinsic strength.

Die Veränderung des axialen Abstandes der Druckstempel voneinander kann durch Verschiebung eines oder beider Druckstempel erfolgt.The change in the axial distance of the plunger from each other can be done by shifting one or both plunger.

Besonders vorteilhaft ist das erfindungsgemäße Verfahren, wenn die umgeformten Rohre einen Außendurchmesser größer als 219 mm aufweisen, beim Umformen eine Vergrößerung des Außendurchmessers um mindestens das 1,5 -fache des Ausgangsaußendurchmessers in einem einzigen Arbeitsgang erfolgt und wenn ein nahtloses Rohr als Ausgangsrohr eingesetzt wird.Particularly advantageous method of the invention, when the formed tubes have an outer diameter greater than 219 mm, during forming a Increasing the outer diameter by at least 1.5 times the Ausgangsausßendurchmessers done in a single operation and when a seamless tube is used as a starting pipe.

Auf überraschend einfache Weise und mit einem hochpräzisen, d.h. in engen Maßtoleranzen liegenden Ergebnis sind mit dem erfindungsgemäßen Verfahren somit Präzisionsrohre für Sonderanwendungen herstellbar bei gleichzeitiger Einsparung von Material. Die Abstimmung des Innendrucks PH und des Axiatdrucks PM erfolgt dabei selbstverständlich in solch einer Weise, dass der Innendruck immer über
einem Wert liegt, der ein "Einknicken" des Rohres auf Grund der Stauchung verhindert und sich ein kontinuierliches Aufweiten, bzw. vergrößern des Durchmessers des Hohlprofils so einstellt, wie es eine gewünschte bzw. geforderte Wandstärke oder die Wandstärke und gleichzeitig die Profillänge erfordem.In a surprisingly simple manner and with a high-precision, ie lying in narrow dimensional tolerances thus precision tubes for special applications can be produced with the inventive method while saving material. Of course, the tuning of the internal pressure P H and the axial pressure P M takes place in such a manner that the internal pressure always exceeds
is a value that prevents "buckling" of the tube due to the compression and a continuous widening, or increase the diameter of the hollow profile sets so as required a desired or required wall thickness or the wall thickness and at the same time the profile length.

Die Größenverhältnisse der Außendurchmesser vor und nach dem Innenhochdruckumformen liegen bei einem Verhältnis von mehr als 1:1,5 und in den jeweiligen materialabhängigen Grenzen von bis zu 1 : 3 des Ausgangs- zum Enddurchmesser. Hierdurch können Rohre mit großem Durchmesser aus Rohren bzw. Hohlprofilen mit relativ geringen Durchmessern hergestellt werden. Das Verfahren ist kostengünstig und leichter durchführbar, als die konventionellen Herstellungsverfahren wie z.B. das Walzen oder das Warmumformen für im Durchmesser große Rohre. Große Durchmesser sind hierbei Bereiche von Außendurchmessern von 219 mm bis über 1000mm.The size ratios of the outer diameter before and after the hydroforming are at a ratio of more than 1: 1.5 and in the respective material-dependent limits of up to 1: 3 of the output to the final diameter. As a result, pipes with a large diameter can be produced from tubes or hollow profiles with relatively small diameters. The process is inexpensive and easier to carry out than the conventional manufacturing processes such as e.g. rolling or hot forming for large diameter pipes. Large diameters are ranges of outside diameters from 219 mm to over 1000 mm.

Vorteilhaft ist es, wenn die jeweiligen Verfahrensparameter, insbesondere der aufgewendete Innendruck PH, der angewendete Axialdruck PM und der axiale Weg der Druckstempel jeweils in Abhängigkeit von dem Material und der Geometrie des als Ausgangsteil dienenden Rohrstückes bzw. des erhaltenen Fertigrohres gespeichert werden. Diese gespeicherten Daten können beim Herstellen von spezifischen Kundenwünschen, d.h. Spezialrohren als Anhaltswerte dienen und können fortlaufend durch gewonnene Parameter ergänzt werden. Die Qualität und Fertigungssicherheit wird vergrößert bzw. ein Produktionsausschuss wird erheblich reduziert.It is advantageous if the respective process parameters, particularly the spent internal pressure P H, the applied axial pressure P M and the axial path are respectively stored the plunger depending on the material and the geometry of serving as starting part pipe piece or of the finished pipe obtained. These stored data can serve as reference values when making specific customer requests, ie special pipes, and can be continuously supplemented by parameters obtained. The quality and manufacturing reliability is increased or a production scrap is considerably reduced.

Die erfindungsgemäße Vorrichtung zum Umformen eines Rohres gemäß dem Verfahren nach den Ansprüchen 1-9, umfasst

  • zwei axial zueinander ausgerichtete Druckstempel, von denen mindestens einer relativ zu dem anderen axial verschiebbar gelagert und durch einen Verschiebeantrieb stufenlos bewegbar ist,
  • wobei deren Stirnflächen als ebene Anlageflächen für das einzuspannende Rohr ausgebildet sind,
  • durch eine Druckerzeugungseinrichtung zum Aufbau eines Innendruckes in dem eingespannten Rohr und
  • eine Steuereinrichtung, mittels der die axiale Bewegung der Druckstempel, deren Anpressdruck an die Stimflächen des eingespannten Rohres und die Höhe des Innendruckes unabhängig voneinander, aber abgestimmt aufeinander, einstellbar sind.
The inventive device for forming a tube according to the method of claims 1-9, comprising
  • two axially aligned plunger, of which at least one is mounted axially displaceable relative to the other and is continuously movable by a displacement drive,
  • wherein the end faces are formed as planar contact surfaces for the pipe to be clamped,
  • by a pressure generating device for establishing an internal pressure in the clamped tube and
  • a control device, by means of which the axial movement of the plunger, the contact pressure of the end faces of the clamped tube and the height of the internal pressure independently but mutually tuned, are adjustable.

Gemäß einer vorteilhaften Ausbildung ist eine Zentriervorrichtung vorgesehen ist, mittels der das einzuspannende Rohr gegenüber den Druckstempeln ausrichtbar ist.According to an advantageous embodiment, a centering device is provided, by means of which the tube to be clamped can be aligned with respect to the pressure punches.

Femer sind an den Stimseiten der Druckstempel Abdichtelemente vorgesehen, welche den Übergang zu den Enden des eingespannten Rohres abdichten.Furthermore, sealing elements are provided on the ends of the plunger, which seal the transition to the ends of the clamped tube.

Zwischen die Druckstempel ist eine Abstützung einbringbar, die die äußere Abmessung des umzuformenden Rohres definiert.Between the plunger, a support can be introduced, which defines the outer dimension of the tube to be formed.

Diese Abstützung kann aus mehreren schalenförmigen, zusammen eine geschlossene Form bildenden Segmenten bestehen.This support may consist of several shell-shaped, together forming a closed shape segments.

Mit der Vorrichtung können im Durchmesser größere Rohre, z.B. mit einem Durchmesser von größer als 219 mm und mit sehr geringen Wandstärken durch Kaltumformen hergestellt werden, deren Wandstärken sehr nahe bei der Mindestwandstärke für einen z.B. nach Regelwerk geforderten Beiastungszustand liegen. Regelwerk können Normenwerke, wie z.B. die ISO-, die EN- oder die DIN-Normen für Rohre sein. Da mittels der Steuerungseinrichtung der Pressvorgang gezielt auf das Endergebnis, d.h. die Hohlprofilgeometrie des herzustellenden Rohres einstellbar ist, können Präzisionsrohre auf sehr einfache und zeitsparende Weise hergestellt werdenWith the device larger diameter pipes, eg with a diameter of greater than 219 mm and with very small wall thicknesses can be produced by cold forming, the wall thicknesses are very close to the minimum wall thickness for example required by regulations Beiastungszustand. Rules may be standards, such as the ISO, EN or DIN standards for pipes. Since by means of the control device of the pressing process targeted to the final result, ie the hollow profile geometry of the tube to be produced adjustable, precision tubes can be produced in a very simple and time-saving manner

Es wurde schon erwähnt, dass bei der Umformung eine Kaltverfestigung erzielbar ist, und zwar geschieht dies durch die durch die Dehnung und Streckung bewirkte Gefügeumwandlung des Materials.
Ein auf diese Weise hergestelltes Rohr weist gegenüber den mit konventionellen Verfahren hergestellten - nicht behandelten - Rohren eine gleichmäßig, feine Gefügestruktur auf. Diese feinere Gefügestruktur führt zu verbesserten Festigkeitswerten bei gleichzeitig sehr geringen Toteranzabweichungen.
Wesentlich ist, dass dies alles im einzigen Verfahrensschritt, also der Umformung, erreicht wird und es somit keiner weiteren - kostenintensiven - Wärmebehandlung bedarf.It has already been mentioned that strain hardening can be achieved during the forming, and this is done by the structural transformation of the material caused by the stretching and stretching.
A tube produced in this way has a uniform, fine microstructure compared to the pipes produced by conventional methods - not treated. This finer microstructure leads to improved strength values combined with very low deadweight deviations.
It is essential that all of this is achieved in the single process step, that is, the forming, and thus no further - costly - heat treatment is required.

Durch die Kaltverfestigung werden generell die Festigkeitswerte des Rohres erhöht, insbesondere die Streckgrenze und die Zugfestigkeit, weshalb ein derartiges Rohr gegenüber den durch Warmumformverfahren hergestellten Hohlprofilen höhere Festigkeitseigenschaften bei relativ dünner Wandstärke aufweist. Gegenüber z.B. Metallrohren, die mittels Walzverfahren hergestellt wurden, weist ein erfindungsgemäßes Metallrohr den Vorteil auf, dass die Oberflächen und die Wandstärken in sehr geringen Toleranzbereichen herstellbar sind. Maßabweichungen auf Grund von Walzbearbeitungen bei der Warmumformung sind hier nicht vorhanden.By work hardening, the strength values of the pipe are generally increased, in particular the yield strength and the tensile strength, which is why such a pipe has higher strength properties compared to the hollow profiles produced by hot forming process with relatively thin wall thickness. Opposite e.g. Metal tubes, which were produced by means of rolling, has a metal tube according to the invention has the advantage that the surfaces and the wall thicknesses can be produced in very small tolerance ranges. Dimensional deviations due to rolling processing during hot forming are not present here.

Nach einer bevorzugten Ausführungsform weist das Hohlprofil eine aktuelle Wandstärke bei oder geringfügig über der rechnerischen Mindestwandstärke auf. Die Toleranzüberschreitung liegt deutlich unterhalb derjenigen von Präzisionsrohren, insbesondere bei weniger als 5 Prozent Toleranzabweichung der Mindestwandstärke des herzustellenden Hohlprofils für eine der geforderten Druckfestigkeit entsprechende Wandstärke. Durch die geringe Maßabweichung wird gegenüber mit konventionellen Verfahren hergestellten Rohren Material eingespart, was insbesondere bei Spezialmaterialien und kostenintensiven Metall-Legierungen oder bei anwendungsbezogenen Gewichtsproblemen vorteilhaft ist.According to a preferred embodiment, the hollow profile at a current wall thickness at or slightly above the mathematical minimum wall thickness. The exceeding of tolerances is significantly below that of precision tubes, in particular with less than 5 percent tolerance deviation of the minimum wall thickness of the hollow profile to be produced for a wall thickness corresponding to the required pressure resistance. The small dimensional deviation saves material compared to tubes produced by conventional methods, which is advantageous in particular for special materials and cost-intensive metal alloys or for application-related weight problems.

Ein Ausführungsbeispiel der Erfindung wird nachfolgend unter Bezugnahme auf die beiliegende Zeichnung beschrieben werden, in welcher zeigen:

  • Fig. 1 eine schematische Schnittansicht einer erfindungsgemäßen Pressvorrichtung mit einem Rohrstück geringen Durchmessers als Ausgangsteil vor Anwendung des erfindungsgemäßen Verfahrens; und
  • Fig. 2 eine schematische Schnittansicht der Pressvonichtung aus Fig. 1 mit einem Rohrstück mit großem Durchmesser nach Anwendung der erfindungsgemäßen Verfahrens.
An embodiment of the invention will now be described with reference to the accompanying drawings, in which:
  • Figure 1 is a schematic sectional view of a pressing device according to the invention with a pipe section of small diameter as an output part prior to application of the method according to the invention. and
  • Fig. 2 is a schematic sectional view of the Pressvonichtung of Fig. 1 with a pipe section with a large diameter after application of the method according to the invention.

In Fig. 1 ist zur Veranschaulichung der Erfindung eine Pressvorrichtung gemäß der Erfindung schematisch in einer Schnittansicht dargestellt, in welcher ein als Ausgangsteil dienendes Rohrstück 1 mit einem Ausgangsdurchmesser DA im Inneren eines Presswerkzeuges 2 angeordnet ist, welches aus einem Werkzeugoberteil 3 und einem Werkzeugunterteil 4 zusammengesetzt ist. Die Werkzeughälften sind jeweils auf einem Maschinenbett 5 und einer von oben angreifenden Pressvorrichtung 6 vorgesehen, welche die zweiteilige Werkzeugform 3, 4 während des Aufweitens des Rohrstückes 1 mittels Innenhochdruck geschlossen halten, Seitlich sind jeweils Druckstempel 7, 8 vorgesehen, welche einerseits die stimseitigen Enden des Rohrstückes 1 zur Anwendung des hydraulischen Innenhochdrucks PH abdichten und andererseits zur Beaufschlagung des Rohres 1 mit einem mechanischen Axialdruck PM vorgesehen sind. In dem rechten Druckstempel 8 ist eine mittige Durchgangsbohrung 9 vorgesehen zur Zufuhr eines hydraulischen Druckmittels von einer in Fig. 1 nicht dargestellten Druckerzeugungsvorrichtung in das Innere des Rohrstücks 1. - Die beiden Werkzeughälften 3, 4, das Werkzeugoberteil 3 und das Werkzeugunterteil 4 weisen eine gleichförmige Innenform auf, entsprechend dem herzustellenden Enddurchmesser DE des Rohrstücks 1 und sind auf der Vorrichtung auswechselbar montiert. Das Werkzeugoberteil 3 ist auf dem Oberstempel 10 montiert, wohingegen das Werkzeug unterteil 4 auf dem Maschinenbett 5 auswechselbar montiert ist.In Fig. 1 for illustrating the invention, a pressing device according to the invention is shown schematically in a sectional view, in which a serving as a starting part pipe piece 1 is arranged with an initial diameter D A inside a pressing tool 2, which consists of a tool upper part 3 and a tool lower part is composed. The tool halves are each provided on a machine bed 5 and a pressing device 6 acting from above, which keep the two-part mold 3, 4 closed during the expansion of the pipe section 1 by means of internal high pressure, each side plunger 7, 8 are provided, which on the one hand the front ends of the Pipe piece 1 for application of the hydraulic high pressure P H seal and on the other hand are provided to act on the pipe 1 with a mechanical axial pressure P M. In the right plunger 8, a central through hole 9 is provided for supplying a hydraulic pressure means of a pressure generating device, not shown in Fig. 1 in the interior of the pipe section 1. - The two tool halves 3, 4, the upper die 3 and the lower tool part 4 have a uniform Inner shape, according to the produced end diameter D E of the pipe section 1 and are interchangeable mounted on the device. The upper tool part 3 is mounted on the upper punch 10, whereas the lower tool part 4 is mounted replaceably on the machine bed 5.

Bei Durchführung des erfindungsgemäßen Verfahrens werden gleichzeitig, wie in Fig. 1 durch Pfeile veranschaulicht, ein hoher hydraulischer Innendruck PH und ein mechanischer Axialdruck PM jeweils von Seiten der Druckstempel 7, 8 auf das Rohrstück 1 in abgestimmter Weise appliziert, so dass eine gewünschte Bauteilgeometrie des herzustellenden Metallrohres 11 in hochpräziser Weise, d.h. engen Maßtoleranzen, herstellbar ist, wie es in Fig. 2 dargestellt ist .When carrying out the method according to the invention are simultaneously, as illustrated in Fig. 1 by arrows, a high hydraulic pressure P H and a mechanical axial pressure P M respectively from the side of the plunger 7, 8 applied to the pipe section 1 in a coordinated manner, so that a desired Component geometry of the produced metal pipe 11 in a high-precision manner, ie narrow dimensional tolerances, can be produced, as shown in Fig. 2.

Wie aus Fig. 2 ersichtlich, ist das Metallrohr 11 nach Anwendung des erfindungsgemäßen Verfahrens bis an die Innenfläche des Werkzeugoberteils 3 und Werkzeughinterteils 4 massiv umgeformt, d,h gepresst, wobei sich eine gewünschte Wandstärke dE des herzustellenden Rohrstücks 11 in Maßabweichungen von weniger als 5 Prozent der herzustellenden Mindestwandstärke einstellt. Die Abstimmung des hydraulischen Innenhochdrucks PH sowie der mechanischen Axialdrucke PM der seitlichen Druckstempel 7, 8 sowie des axialen Weges a der Druckstempel erfolgt in einer derartigen Weise, dass genau die Wandstärke dE des herzustellenden Metallrohres trotz der im dargestellten Ausführungsbeispiel etwa 2 fachen Durchmesservergrößerung hergestellt werden können. Entsprechend der geforderten Wandstärke dE und dem Aufweitungsgrad ist das hergestellte Rohr 11 gegenüber dem Ausgangsrohrstück 1 verkürzt. Auf diese Weise lassen sich Präzisionsrohre mit großem Durchmesser und nur sehr geringen Wandstärken in nur einem einzigen und überraschend einfachen Produktionsschritt herstellen. Durch die Erfindung lassen sich somit Spezialrohre, insbesondere aus teuren Materialien auf denkbar einfache Weise herstellen,As can be seen from FIG. 2, the metal tube 11 is massively deformed after application of the method according to the invention up to the inner surface of the upper tool part 3 and the tool rear part 4, d, h, wherein a desired wall thickness d E of the pipe section 11 to be produced deviates less than 5 percent of the minimum wall thickness to be produced. The vote of the hydraulic high pressure P H and the mechanical axial pressures P M of the lateral plunger 7, 8 and the axial path a of the plunger takes place in such a way that exactly the wall thickness d E of the metal tube to be produced despite the illustrated embodiment about 2 times the diameter increase can be produced. According to the required wall thickness d E and the degree of expansion of the produced tube 11 is shortened relative to the output pipe piece 1. In this way, precision tubes with a large diameter and only very small wall thickness can be produced in a single and surprisingly simple production step. By means of the invention, it is thus possible to produce special tubes, in particular of expensive materials, in a very simple way,

Die Möglichkeiten, die das erfindungsgemäße Verfahren bietet, sollen nachfolgend an Beispielen erläutert werden.The possibilities offered by the process according to the invention will be explained below by way of examples.

Ausgangsprodukt ist jeweils ein NPS 8", Sched. 80S (12,70mm), Länge 6,00 m
1. Bei gleichbleibendem Durchmesser, zunehmender Wandstärke und verringerter Länge, lassen sich herstellen:

  • Sched. 100 (15,06 mm) Rohre der Länge 5,12 m
  • Sched. 120 (18,24 mm) Rohre der Länge 4,29 m
  • Sched. 140 (20,62 mm) Rohre der Länge 3,84 m
  • Sched. 160 (23,01 mm) Rohre der Länge 3,49 m
  • Sched. xxs (22,23 mm) Rohre der Länge 3,59 m

2. Bei vergrößertem Durchmesser, gleichbleibender Wandstärke und verringerter Länge, lassen sich herstellen: NPS 19" Sched.80 Länge 4,76 m NPS 12" Sched.80 Länge 3,98 m NPS 14" Sched.80 Länge 3,48 m NPS 16" Sched.80 Länge 3,15 m NPS 18" Sched.80 Länge 2,79 m NPS 20" Sched.80 Länge 2,50 m NPS 22" Sched.80 Länge 2,27 m NPS 24" Sched. 80 Länge 2,08 m
3. Bei vergrößertem Durchmesser, verringerter Wandstärke und gleichbleibender Länge, lassen sich Rohre herstellen: Sched. 40 S(+) NPS 10" 10,19 mm Sched. 30 (+) NPS 12" 8,59 mm Sched. 20(-) NPS 14" 7,84 mm Sched.10 (+) NPS 16" 6,86 mm Sched. 10 (-) NPS 18" 6,09 mm Sched. 10 S NPS 20" 5,48 mm Sched. 10 S(-) NPS 22" 4,99 mm NPS 24" 4,57 mm
Diese Beispiele zeigen die Vielfalt der Möglichkeiten Rohre unterschiedlichster Abmessungen - ausgehend von einer Ausgangsabmessung - herstellen zu können. The starting product is a NPS 8 ", Sched. 80S (12.70 mm), length 6.00 m
1. With constant diameter, increasing wall thickness and reduced length, can be produced:
  • Sched. 100 (15.06 mm) tubes of length 5.12 m
  • Sched. 120 (18.24 mm) pipes of length 4.29 m
  • Sched. 140 (20,62 mm) pipes of length 3,84 m
  • Sched. 160 (23.01 mm) pipes of length 3.49 m
  • Sched. xxs (22.23 mm) pipes of length 3.59 m

2. With increased diameter, constant wall thickness and reduced length, can be produced: NPS 19 " Sched.80 Length 4.76 m NPS 12 " Sched.80 Length 3.98 m NPS 14 " Sched.80 Length 3.48 m NPS 16 " Sched.80 Length 3.15 m NPS 18 " Sched.80 Length 2.79 m NPS 20 " Sched.80 Length 2.50 m NPS 22 " Sched.80 Length 2.27 m NPS 24 " Sched. 80 Length 2.08 m
3. With increased diameter, reduced wall thickness and consistent length, pipes can be manufactured: Sched. 40s (+) NPS 10 " 10.19 mm Sched. 30 (+) NPS 12 " 8,59 mm Sched. 20 (-) NPS 14 " 7.84 mm Sched.10 (+) NPS 16 " 6.86 mm Sched. 10 (-) NPS 18 " 6.09 mm Sched. 10 s NPS 20 " 5.48 mm Sched. 10 S (-) NPS 22 " 4.99 mm NPS 24 " 4.57 mm
These examples show the variety of possibilities of producing tubes of different dimensions - starting from an initial dimension.

Claims (15)

  1. Method for reshaping a tube (1) gripped between two pressing dies (7, 8) which can be moved axially, which tube has an original external diameter (DA), an original wall thickness and an original length, by means of hydraulic pressure formed in its interior, into a finished tube which has a different external diameter or a different length and / or a different wall thickness in comparison with the original tube, wherein the original tube is cold-formed simultaneously and evenly over its entire length,
    characterised in that
    the amount of the hydraulic internal pressure (PH), of the mechanical axial pressure (PM), the axial movement of the pressing dies and their contact pressure acting on the ends of the tube are coordinated with each other in such a way that
    - when the hydraulic internal pressure is increased and the axial distance between the pressing dies is kept the same, the external diameter is increased while the wall thickness is reduced,
    - when the hydraulic internal pressure is increased and the axial distance between the pressing dies is reduced by the application of mechanical axial pressure, the external diameter is increased, the wall thickness stays the same and the length of the tube is reduced, and
    - where the hydraulic internal pressure is kept at the same level, a decrease in the axial distance between the pressing dies effected by mechanical axial pressure, and the original external diameter of the tube remains the same, the length of the tube is reduced and the wall thickness is increased.
  2. Method as in claim 1,
    characterised in that
    the reshaping of the original tube to form the finished tube is effected continuously and at a constant speed.
  3. Method as in one of the preceding claims,
    characterised in that
    the degree of reshaping is chosen, depending on the material, so that a structural conversion leading to strain hardening sets in.
  4. Method as in one of the preceding claims,
    characterised in that
    while the external diameter of the tube is increasing, the internal pressure is reduced and the contact pressure of the pressing dies on the ends of the tubes is adjusted.
  5. Method as in one of the preceding claims,
    characterised in that
    the pressing dies act only on the end faces of the ends of the tubes that are facing towards them.
  6. Method as in one of the preceding claims,
    characterised in that
    the axial spacing between the pressing dies is changed by moving one or both pressing dies.
  7. Method as in one of the preceding claims,
    characterised in that
    the reshaped tubes have an external diameter of more than 219 mm.
  8. Method as in one of the preceding claims,
    characterised in that
    during the reshaping process, the external diameter is increased by a minimum of 1.5 times the original external diameter in a single operation.
  9. Method as in one of the preceding claims,
    characterised in that
    a seamless tube is used as the original tube.
  10. Device for reshaping a tube in accordance with the method as given in claims 1 to 9,
    characterised
    - by two pressure dies (7, 8) in axial alignment with each other, of which at least one is positioned so that it can be moved axially in relation to the other one and can be moved in an infinitely variable manner by means of a sliding drive unit,
    - wherein its end faces are made to form flat bearing surfaces for the tube (1) that is to be gripped,
    - by an apparatus to generate pressure in order to create internal pressure inside the gripped tube, and
    characterised by
    - a control facility by means of which the axial movement of the pressing dies (7, 8), their contact pressure on the end faces of the gripped tube, and the level of the internal pressure can be adjusted independently of each other but coordinated with each other.
  11. Device as in claim 10,
    characterised in that
    there is a centring device by means of which the gripped tube can be aligned in relation to the pressure dies (7, 8).
  12. Device as in one of the preceding claims,
    characterised in that
    there are sealing elements on the end faces of the pressure dies (7, 8), which elements seal off the changeover to the ends of the gripped tube.
  13. Device as in one of the preceding claims,
    characterised in that
    a support can be put in place between the pressure dies (7, 8), which support defines the external dimensions of the tube that is to be reshaped.
  14. Device as in claim 13,
    characterised in that
    the support is made up of a closed template.
  15. Device as in claim 13,
    characterised in that
    the support is made up of a number of saucer-shaped segments which combine to form a closed template.
EP02787390A 2001-11-21 2002-11-19 Method and device for reshaping tubes Revoked EP1446245B1 (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
DE10156978 2001-11-21
DE10156978 2001-11-21
DE10241641 2002-09-05
DE10241641A DE10241641A1 (en) 2001-11-21 2002-09-05 Tube deforming process involves cold-deforming tube blank simultaneously and uniformly over its entire length at specified internal, axial and end pressures
PCT/DE2002/004310 WO2003045604A1 (en) 2001-11-21 2002-11-19 Method and device for reshaping tubes

Publications (2)

Publication Number Publication Date
EP1446245A1 EP1446245A1 (en) 2004-08-18
EP1446245B1 true EP1446245B1 (en) 2006-03-08

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JP (1) JP2005510363A (en)
AT (1) ATE319526T1 (en)
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DE (1) DE50206047D1 (en)
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US6446476B1 (en) * 2001-11-30 2002-09-10 General Motors Corporation Hydroforming method and apparatus

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JP2005510363A (en) 2005-04-21
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WO2003045604A1 (en) 2003-06-05
US7251972B2 (en) 2007-08-07
EP1446245A1 (en) 2004-08-18
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DE50206047D1 (en) 2006-05-04
US20050000259A1 (en) 2005-01-06

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