EP0141350B1 - Method of preparing work pieces from metal powder - Google Patents

Method of preparing work pieces from metal powder Download PDF

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Publication number
EP0141350B1
EP0141350B1 EP84112605A EP84112605A EP0141350B1 EP 0141350 B1 EP0141350 B1 EP 0141350B1 EP 84112605 A EP84112605 A EP 84112605A EP 84112605 A EP84112605 A EP 84112605A EP 0141350 B1 EP0141350 B1 EP 0141350B1
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EP
European Patent Office
Prior art keywords
capsule
outer shell
approximately
circumferential surface
flexibly extensible
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP84112605A
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German (de)
French (fr)
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EP0141350A1 (en
Inventor
Christer Aslund
Claes Tornberg
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nyby Uddeholm Powder AB
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Nyby Uddeholm Powder AB
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Publication of EP0141350A1 publication Critical patent/EP0141350A1/en
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/02—Compacting only
    • B22F3/04—Compacting only by applying fluid pressure, e.g. by cold isostatic pressing [CIP]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/02—Compacting only
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/12—Both compacting and sintering
    • B22F3/1208—Containers or coating used therefor
    • B22F3/1216—Container composition
    • B22F3/1233—Organic material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/12—Both compacting and sintering
    • B22F3/1208—Containers or coating used therefor
    • B22F3/1216—Container composition
    • B22F3/1241—Container composition layered
    • 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
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S29/00—Metal working
    • Y10S29/031—Pressing powder with other step
    • 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
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
    • Y10T428/1352—Polymer or resin containing [i.e., natural or synthetic]
    • Y10T428/1355—Elemental metal containing [e.g., substrate, foil, film, coating, etc.]
    • Y10T428/1359—Three or more layers [continuous layer]
    • 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
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913—Rod, strand, filament or fiber
    • Y10T428/2973—Particular cross section
    • Y10T428/2975—Tubular or cellular

Definitions

  • the invention relates to a process for the production of tubes in which the powder of metal and / or metal alloys is filled into a thin-walled capsule, the capsule is then closed and subjected to cold isostatic pressure, as a result of which the powder is compressed within the capsule to form a shape-retaining shape Pipe blanks, wherein the outer shell of the capsule has at least one approximately straight weld seam extending in the longitudinal direction of the pipe.
  • the weld seam extending in the longitudinal direction of the pipe represents an extremely critical area in the production of the pipe blank.
  • a longitudinal fold is formed which extends into the interior of the capsule.
  • the pipe blank must be discarded as a committee. The resulting losses in machine time and material are obvious.
  • US-A-2 932 882 discloses a method for coating a metal body with a. Layer of particularly corrosion-resistant material are removed, for this purpose the metal body, which can be made by powder metallurgy, is arranged within a deformable sleeve made of corrosion-resistant material and this arrangement is placed inside a container made of elastically stretchable material, in particular inside a rubber bag, and then exert pressure on the entire unit in the range of 1,000 to 60,000 psi. (6.9-413 N / mm2). This is intended to achieve a close connection between the metal body and the deformable sleeve made of corrosion-resistant material with corresponding deformation thereof. US-A-2 932 882 does not provide an indication of how to solve the above problem.
  • the outer shell of the capsule is provided with an elastically stretchable layer in such a way that an approximately uniform prestress is applied to the outer surface, the thickness of the elastically stretchable layer being approximately the same corresponds to one to two times the wall thickness of the capsule shell.
  • the method according to the invention for producing elongated tubes has proven to be particularly advantageous.
  • the measure according to the invention to provide the circumferential surface comprising the weld seam with an elastically stretchable layer of hard rubber or similar material in such a way that an approximately uniform prestress is applied to this surface, an approximately uniform pressure distribution is achieved over the entire circumference of the capsule shell. In this way, wrinkling along the weld seam when the cold isostatic pressure is applied is surprisingly avoided. It is.
  • an essential prerequisite for the function of the elastically stretchable layer is that it lies closely against the outer surface of the capsule shell and preferably exerts an approximately uniform surface pressure.
  • the elastically stretchable layer can be pulled or put over the outer surface of the capsule shell.
  • the elastically stretchable layer is fixed by means of hose clamps or adhesive strips in the area of the front ends of the capsule.
  • a particularly simple solution is the use of a sleeve made of elastically stretchable material, which has approximately the same length as the capsule and an inner diameter which is slightly less than the outer diameter of the capsule. This sleeve is pulled over the outer shell of the capsule before the cold isostatic pressure is applied. Due to the diameter ratio mentioned, a tight fit is guaranteed after being fitted onto the outer shell of the capsule. It is also ensured that the elastically stretchable layer formed in this way exerts an approximately uniform surface pressure on the lateral surface.
  • the front ends of the elastically stretchable and pressure-distributing layer are preferably designed to be somewhat thicker, in order in this way to compensate for the additional pressure on the capsule on the front side.
  • the tubular capsule 10 according to FIGS. 1 and 2 is filled with preferably spherical powder 13 made of metal and / or metal alloys and is closed on all sides.
  • the inner tubular jacket 11 is formed in one piece, while the outer tubular jacket 12 consists of a thin-walled sheet metal blank bent into a cylindrical sleeve, the abutting longitudinal edges of which are connected to one another by means of an approximately rectilinear weld seam 14 which extends in the longitudinal direction of the capsule.
  • the risk of wrinkles in the area of the weld seam 14 can be reliably avoided by the fact that the outer surface of the weld seam (outer tubular jacket 12) with an elastically stretchable layer 15, for. B. in the form of a sleeve made of elastically stretchable material, such as hard rubber, rubber, or the like, is surrounded ( Figures 3 and 4).
  • the sleeve 15 made of elastically stretchable material and drawn over the outer jacket 12 has a greater thickness in the region of the front ends of the capsule 10 than in the region in between. This compensates for the pressurization of the capsule 10 on the face side.
  • the inner diameter of the elastic, stretchable sleeve 15 is somewhat smaller than the outer diameter of the capsule 10 or the outer capsule shell 12, so that it is ensured that the sleeve 15 lies tightly or closely against the outer shell 12 of the capsule 10 and there is a somewhat uniform prestressing thereon exercises.
  • the sleeve 15 made of elastically stretchable material causes an approximately uniform pressure distribution when a cold isostatic pressure is applied, as a result of which the aforementioned wrinkling in the region of the longitudinal weld seam 14 is avoided. This fold is identified in FIG. 2 by reference number 16.
  • the sleeve 15 made of elastically stretchable material is fixed in the embodiment according to FIGS. 3 and 4 in the region of the front ends of the capsule 10 by means of hose bands 17 of a conventional type.
  • the elastically stretchable layer is also relatively thin-walled.
  • the wall thickness corresponds approximately to the wall thickness of the capsule skin.
  • the wall thickness of the elastically stretchable layer 15 is preferably approximately twice as large as the wall thickness of the capsule skin 11 or 12.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Powder Metallurgy (AREA)
  • Press-Shaping Or Shaping Using Conveyers (AREA)

Description

Die Erfindung betrifft ein Verfahren zur Herstellung von Rohren bei dem Pulver aus Metall und/oder Metall-Legierungen in eine dünnwandige Kapsel eingefüllt, die Kapsel anschließend verschlossen und einem kaltisostatischen Druck ausgesetzt wird, wodurch eine Verdichtung des Pulvers innerhalb des Kapsel erfolgt unter Ausbildung eines formbeständigen Rohr-Rohlings, wobei der Außenmantel der Kapsel mindestens eine sich in Rohrlängsrichtung erstreckende, etwa geradlinige Schweißnaht aufweist.The invention relates to a process for the production of tubes in which the powder of metal and / or metal alloys is filled into a thin-walled capsule, the capsule is then closed and subjected to cold isostatic pressure, as a result of which the powder is compressed within the capsule to form a shape-retaining shape Pipe blanks, wherein the outer shell of the capsule has at least one approximately straight weld seam extending in the longitudinal direction of the pipe.

Die sich in Rohrlängsrichtung erstreckende Schweißnaht stellt bei der Herstellung des Rohr-Rohlings einen äußerst kritischen Bereich dar. Versuche haben gezeigt, daß längs der Schweißnaht in unmittelbarer Nähe derselben beim Aufbringen des kaltisostatischen Drucks, d. h. bei der kaltisostatischen Verpressung, eine sich in das Kapselinnere ausdehenede Längsfalte entsteht. Der Rohr-Rohling muß in einem solchen Fall als Ausschuß ausgesondert werden. Die dadurch entstehenden Verluste an Maschinenzeit und Material sind augenscheinlich.The weld seam extending in the longitudinal direction of the pipe represents an extremely critical area in the production of the pipe blank. Experiments have shown that along the weld seam in the immediate vicinity thereof when the cold isostatic pressure is applied, i. H. in cold isostatic pressing, a longitudinal fold is formed which extends into the interior of the capsule. In such a case, the pipe blank must be discarded as a committee. The resulting losses in machine time and material are obvious.

Der US-A-2 932 882 kann ein Verfahren zur Beschichtung eines Metallkörpers mit einer . Schicht aus besonders korrosionsbeständigem Material entnommen werden, wobei zu diesem Zweck der Metallkörper, der pulvermetallurgisch hergestellt sein kann, innerhalb einer deformierbaren Hülse aus korrosionsbeständigem Material angeordnet und diese Anordnung innerhalb eines Behälters aus elastisch dehnbarem Material, insbesondere innerhalb eines Gummibeutels, plaziert wird, um dann auf die gesamte Einheit Druck auszuüben in der Größenordnung von 1.000 bis 60.000 psi. (6,9-413 N/mm2). Dadurch soll eine enge Verbindung zwischen dem Metallkörper und der deformierbaren Hülse aus korrosionsbeständigem Material unter entsprechender Verformung derselben erzielt werden. Einen Hinweis zur Lösung des oben dargestellten Problems vermittelt die US-A-2 932 882 nicht.US-A-2 932 882 discloses a method for coating a metal body with a. Layer of particularly corrosion-resistant material are removed, for this purpose the metal body, which can be made by powder metallurgy, is arranged within a deformable sleeve made of corrosion-resistant material and this arrangement is placed inside a container made of elastically stretchable material, in particular inside a rubber bag, and then exert pressure on the entire unit in the range of 1,000 to 60,000 psi. (6.9-413 N / mm2). This is intended to achieve a close connection between the metal body and the deformable sleeve made of corrosion-resistant material with corresponding deformation thereof. US-A-2 932 882 does not provide an indication of how to solve the above problem.

Das gleiche gilt für den aus der US-A-3 551 946 bekannten Stand der Technik. Dort ist eine Kompressionsbehälter beschrieben bestehend aus einer Papphülse, Pappdecke und Pappboden, die durch eine Gummihülse, Gummi-Deckelhaube und Gummi-Bodenhaube zusammengehalten sind, wobei die gesamte Anordnung innerhalb eines äußeren, evakuierbaren Gummibehälters plaziert ist unter Einschluß einer mit Metallpartikel gefüllten Kapsel, deren Boden und Deckel jeweils lose angeordnet sind. Der vorliegenden Erfindung liegt die Aufgabe zugrunde, bei der Herstellung eines Rohr-Rohlings nach dem eingangs genannten Verfahren die erwähnte Faltenbildung während der isostatischen Verpressung im Bereich der Schweißnaht zu vermeiden.The same applies to the prior art known from US-A-3,551,946. There a compression container is described consisting of a cardboard sleeve, cardboard cover and cardboard base, which are held together by a rubber sleeve, rubber cover hood and rubber base cover, the entire arrangement being placed within an outer, evacuable rubber container, including a capsule filled with metal particles, the Bottom and lid are loosely arranged. The present invention has for its object to avoid the aforementioned wrinkle formation during isostatic pressing in the region of the weld seam in the manufacture of a tube blank according to the aforementioned method.

Diese Aufgabe wird in überraschend einfacher Weise dadurch gelöst, daß vor dem Aufbringen des kaltisostatischen Drucks der Außenmantel der Kapsel mit einer elastisch dehnbaren Schicht versehen wird derart, daß auf die Mantelfläche eine etwa gleichmäßige Vorspannung aufgebracht wird, wobei die Dicke der elastisch dehnbaren Schicht etwa der ein - bis zweifachen Wandstärke des Kapselmantels entspricht.This object is achieved in a surprisingly simple manner in that, before the cold isostatic pressure is applied, the outer shell of the capsule is provided with an elastically stretchable layer in such a way that an approximately uniform prestress is applied to the outer surface, the thickness of the elastically stretchable layer being approximately the same corresponds to one to two times the wall thickness of the capsule shell.

Bevorzugte Ausführungsformen der Erfindung sind in den Unteransprüchen beschrieben.Preferred embodiments of the invention are described in the subclaims.

Als besonders vorteilhaft hat sich das erfindungsgemäße Verfahren zur Herstellung von langgestreckten Rohren herausgestellt.The method according to the invention for producing elongated tubes has proven to be particularly advantageous.

Durch die erfindungsgemäße Maßnahme, die die Schweißnaht umfassende Mantelfläche mit einer elastisch dehnbaren Schicht aus Hartgummi oder ähnlichem Material zu versehen derart, daß diese Fläche mit einer etwa gleichmäßigen Vorspannung beaufschlagt wird, wird eine etwa gleichförmige Druckverteilung über den gesamten Umfang des Kapselmantels erzielt. Auf diese Weise wird überraschend eine Faltenbildung längs der Schweißnaht beim Aufbringen des kaltisostatischen Drucks sicher vermieden. Es ist. natürlich wesentliche Voraussetzung für die Funktion der elastisch dehnbaren Schicht daß diese dicht an der Außenfläche des Kapselmantels anliegt und vorzugsweise einen etwa gleichmaßigen Flächendruck ausübt.By the measure according to the invention, to provide the circumferential surface comprising the weld seam with an elastically stretchable layer of hard rubber or similar material in such a way that an approximately uniform prestress is applied to this surface, an approximately uniform pressure distribution is achieved over the entire circumference of the capsule shell. In this way, wrinkling along the weld seam when the cold isostatic pressure is applied is surprisingly avoided. It is. Of course, an essential prerequisite for the function of the elastically stretchable layer is that it lies closely against the outer surface of the capsule shell and preferably exerts an approximately uniform surface pressure.

Die elastisch dehnbare Schicht kann auf die Außenfläche des Kapselmantels gezogen bzw. gestülpt werden. Die Fixierung der elastisch dehnbaren Schicht erfolgt mittels Schlauchschellen oder Klebestreifen im Bereich der stirnseitigen Enden der Kapsel.The elastically stretchable layer can be pulled or put over the outer surface of the capsule shell. The elastically stretchable layer is fixed by means of hose clamps or adhesive strips in the area of the front ends of the capsule.

Eine besonders einfache Lösung stellt die Verwendung einer Hülse aus elastisch dehnbarem Material dar, die etwa dieselbe Länge wie die Kapsel und einen inneren Durchmesser aufweist, der etwas geringer ist als der Außendurchmesser der Kapsel. Diese Hülse wird vor Aufbringen des kaltisostatischen Drucks über den Außenmantel der Kapsel gezogen. Aufgrund der erwähnten Durchmesserverhäftnisse ist ein dichtes Anliegen nach dem Aufziehen auf den Außenmantel der Kapsel gewährleistet. Es ist ferner sichergestellt, daß die derart ausgebildete elastisch dehnbare Schicht auf die Mantelfläche einen etwa gleichmäßigen Flächendruck ausübt.A particularly simple solution is the use of a sleeve made of elastically stretchable material, which has approximately the same length as the capsule and an inner diameter which is slightly less than the outer diameter of the capsule. This sleeve is pulled over the outer shell of the capsule before the cold isostatic pressure is applied. Due to the diameter ratio mentioned, a tight fit is guaranteed after being fitted onto the outer shell of the capsule. It is also ensured that the elastically stretchable layer formed in this way exerts an approximately uniform surface pressure on the lateral surface.

Vorzugsweise sind die stirnseitigen Enden der elastisch dehnbaren und druckverteilenden Schicht etwas stärker ausgebildet, um auf diese Weise die zusätzliche stirnseitige Druckbeaufschlagung der Kapsel zu kompensieren.The front ends of the elastically stretchable and pressure-distributing layer are preferably designed to be somewhat thicker, in order in this way to compensate for the additional pressure on the capsule on the front side.

Nachstehend wird das erfindungsgemäße Verfahren anhand eines Ausführungsbeispieles, das in der anliegenden Zeichnung schematisch dargestellt ist, nochmals erläutert. Es zeigen :

  • Figur 1 eine rohrförmige und mit Metallpulver gefüllte Kapsel, die nach dem herkömmlichen Verfahren verpresst ist, im Längsschnitt,
  • Figur 2 die Kapsel nach Figur 1 im Querschnitt,
  • Figur 3 eine nach dem erfindungsgemäßen Verfahren verpresste Kapsel im Längsschnitt, und
  • Figur 4 die Kapsel nach Figur 3 im Querschnitt.
The method according to the invention is explained again below using an exemplary embodiment which is shown schematically in the accompanying drawing. Show it :
  • FIG. 1 shows a longitudinal section of a tubular capsule filled with metal powder, which is pressed by the conventional method,
  • FIG. 2 shows the capsule according to FIG. 1 in cross section,
  • 3 shows a capsule pressed according to the inventive method in longitudinal section, and
  • Figure 4 shows the capsule of Figure 3 in cross section.

Die rohrförmige Kapsel 10 nach den Figuren 1 und 2 ist mit vorzugsweise sphärischem Pulver 13 aus Metall und/oder Metallegierungen gefüllt und allseitig geschlossen. Der innere Rohrmantel 11 ist einstückig ausgebildet, während der äußere Rohrmantel 12 aus einem zu einer zylindrischen Hülse gebogenen dünnwandigen Blechzuschnitt besteht, dessen aneinanderstoßende Längskanten mittels einer etwa geradlinigen, sich in Kapsellängsrichtung erstreckenden Schweißnaht 14 miteinander verbunden sind. Beim Aufbringen eines kaltisostatischen Drucks zum Zwecke der Verpressung des Metallpulvers innerhalb der Kapsel 10 zu einem insgesamt festen bzw. formbeständigen Gegenstand (Rohrabschnitt) besteht die Gefahr, daß sich in unmittelbarer Nähe der Verbindungschweißnaht 14 eine sich in das Kapselinnere ertreckende Längsfalte bildet, die selbstverständlich unerwünscht ist. Der verpresste Gegenstand muß in einem solchen Fall als Ausschuß ausgesondert werden. Die Längsfalte entsteht offensichtlich durch eine Art Kerbwirkung der Schweißnaht 14.The tubular capsule 10 according to FIGS. 1 and 2 is filled with preferably spherical powder 13 made of metal and / or metal alloys and is closed on all sides. The inner tubular jacket 11 is formed in one piece, while the outer tubular jacket 12 consists of a thin-walled sheet metal blank bent into a cylindrical sleeve, the abutting longitudinal edges of which are connected to one another by means of an approximately rectilinear weld seam 14 which extends in the longitudinal direction of the capsule. When applying a cold isostatic pressure for the purpose of pressing the metal powder inside the capsule 10 to form an overall solid or dimensionally stable object (pipe section), there is a risk that a longitudinal fold extending into the interior of the capsule will form in the immediate vicinity of the connecting weld seam, which of course is undesirable is. In such a case, the pressed object must be discarded as a committee. The longitudinal fold obviously arises from a type of notch effect of the weld seam 14.

Überraschenderweise hat sich gezeigt, daß die Gefahr einer Faltenbildung im Bereich der Schweißnaht 14 sicher dadurch vermieden werden kann, daß die die Schweißnaht umfassende Mantelfläche (äußerer Rohrmantel 12) mit einer elastisch dehnbaren Schicht 15, z. B. in Form einer Hülse aus elastisch dehnbarem Material, wie Hartgummi, Kautschuk, oder dergleichen, umgeben wird (Figuren 3 und 4). Bei der Ausführungsform nach den Figuren 3 und 4 weist die über den Außenmantel 12 gezogene Hülse 15 aus elastisch dehnbarem Material im Bereich der stirnseitigen Enden der Kapsel 10 eine größere Dicke auf als im Bereich dazwischen. Dadurch wird eine Kompensierung der stirnseitigen Druckbeaufschlagung der Kapsel 10 erreicht. Der Innendurchmesser der elastischen dehnbaren Hülse 15 ist etwas geringer als der Außendurchmesser der Kapsel 10 bzw. des äußeren Kapselmantels 12, so daß sichergestellt ist, daß die Hülse 15 dicht bzw. eng am Außenmantel 12 der Kapsel 10 anliegt und auf diesen eine etwas gleichmäßige vorspannung ausübt. Die Hülse 15 aus elastisch dehnbarem Material bewirkt eine etwa gleichförmige Druckverteilung beim Aufbringen eines kaltisostatischen Drucks, wodurch die erwähnte Faltenbildung im Bereich der Längsschweißnaht 14 vermieden wird. Diese Falte ist in Figur 2 mit der Bezugsziffer 16 gekennzeichnet.Surprisingly, it has been shown that the risk of wrinkles in the area of the weld seam 14 can be reliably avoided by the fact that the outer surface of the weld seam (outer tubular jacket 12) with an elastically stretchable layer 15, for. B. in the form of a sleeve made of elastically stretchable material, such as hard rubber, rubber, or the like, is surrounded (Figures 3 and 4). In the embodiment according to FIGS. 3 and 4, the sleeve 15 made of elastically stretchable material and drawn over the outer jacket 12 has a greater thickness in the region of the front ends of the capsule 10 than in the region in between. This compensates for the pressurization of the capsule 10 on the face side. The inner diameter of the elastic, stretchable sleeve 15 is somewhat smaller than the outer diameter of the capsule 10 or the outer capsule shell 12, so that it is ensured that the sleeve 15 lies tightly or closely against the outer shell 12 of the capsule 10 and there is a somewhat uniform prestressing thereon exercises. The sleeve 15 made of elastically stretchable material causes an approximately uniform pressure distribution when a cold isostatic pressure is applied, as a result of which the aforementioned wrinkling in the region of the longitudinal weld seam 14 is avoided. This fold is identified in FIG. 2 by reference number 16.

Die Hülse 15 aus elastisch dehnbarem Material ist bei dem Ausführungsbeispiel nach den Figuren 3 und 4 im Bereich der stirnseitigen Enden der Kapsel 10 mittels Schlauchbändern 17 herkömmlicher Art fixiert.The sleeve 15 made of elastically stretchable material is fixed in the embodiment according to FIGS. 3 and 4 in the region of the front ends of the capsule 10 by means of hose bands 17 of a conventional type.

Die elastisch dehnbare Schicht ist ebenfalls relativ dünnwandig. Die Wandstärke entspricht etwa der Wandstärke der Kapselhaut. Vorzugsweise ist die Wandstärke der elastisch dehnbaren Schicht 15 etwa doppelt so groß wie die Wandstärke der Kapselhaut 11 bzw. 12.The elastically stretchable layer is also relatively thin-walled. The wall thickness corresponds approximately to the wall thickness of the capsule skin. The wall thickness of the elastically stretchable layer 15 is preferably approximately twice as large as the wall thickness of the capsule skin 11 or 12.

Claims (4)

1. Process for the production of pipes, in which powder of metal and/or metal alloys is filled in a thinwalled capsule, the capsule is subsequently closed and exposed to a cold-isostatic pressure, a compaction of the powder taking place within the capsule and forming a dimensionally stable pipe blank, the outer shell of the capsule having at least one approximately straight weld extending in the longitudinal direction of the pipe and, before application of the cold-isostatic pressure, the outer shell of the capsule being provided with a flexibly extensible layer, such that an approximately even pretension is applied to the circumferential surface, the thickness of the flexibly extensible layer corresponding to approximately one to two times the wall thickness of the capsule shell.
2. Process according to claim 1, characterized in that the outer shell of the capsule is provided with a flexibly extensible layer, the thickness of which is greater in the region of the end faces of the capsule than in the region in between.
3. Process according to claim 1 or 2, characterized in that the outer shell of the capsule is coated with a flexibly extensible material which shrinks after application to the circumferential surface, so that an approximately even pretension is applied to the circumferential surface.
4. Process according to one of claims 1 to 5, characterized in that the flexibly extensible layer, is fixed at the end faces of the capsule to the circumferential surface of the capsule by means of hose clip-like retaining means, adhesive strips or the like.
EP84112605A 1983-10-21 1984-10-18 Method of preparing work pieces from metal powder Expired EP0141350B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3338369 1983-10-21
DE3338369A DE3338369C1 (en) 1983-10-21 1983-10-21 Process for the manufacture of powder metallurgical objects

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EP0141350A1 EP0141350A1 (en) 1985-05-15
EP0141350B1 true EP0141350B1 (en) 1988-09-07

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EP84112605A Expired EP0141350B1 (en) 1983-10-21 1984-10-18 Method of preparing work pieces from metal powder

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US (1) US4565668A (en)
EP (1) EP0141350B1 (en)
JP (1) JPS60145303A (en)
KR (1) KR850004035A (en)
DE (2) DE3338369C1 (en)

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US5244623A (en) * 1991-05-10 1993-09-14 Ferro Corporation Method for isostatic pressing of formed powder, porous powder compact, and composite intermediates
AT411580B (en) * 2001-04-11 2004-03-25 Boehler Edelstahl METHOD FOR THE POWDER METALLURGICAL PRODUCTION OF OBJECTS
JP3801189B2 (en) * 2002-08-20 2006-07-26 松下電器産業株式会社 Bit reduction device
US9234610B2 (en) * 2007-11-07 2016-01-12 Parker-Hannifin Corporation Aluminum foil based hose
US9199308B2 (en) 2011-09-20 2015-12-01 GM Global Technology Operations LLC Method of producing composite articles and articles made thereby
CN109014219A (en) * 2018-09-14 2018-12-18 河南德源净化装备有限公司 A kind of production method of the powder sintered screen pipe of smooth outer surface type
CN109365824B (en) * 2018-10-25 2021-06-25 西安石油大学 Preparation method of 6.5 wt% high-silicon electrical steel thin-wall hollow pipe
CN115740448A (en) * 2022-12-02 2023-03-07 同创(丽水)特种材料有限公司 Cold isostatic pressing preparation method of metal bar
CN117947386B (en) * 2024-03-26 2024-06-25 成都晨发泰达航空科技股份有限公司 High-density EB-PVD metal coating and preparation method thereof

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US1081618A (en) * 1912-03-28 1913-12-16 Westinghouse Lamp Co Process of preparing billets of refractory materials.
US2932882A (en) * 1954-02-25 1960-04-19 Jr John C R Kelly Method of preparing powdered refractory metals for mechanical working
FR1282645A (en) * 1960-12-13 1962-01-27 Commissariat Energie Atomique Improvements to processes for the agglomeration of powders, in particular metallic, in particular uranium
US3551946A (en) * 1968-08-26 1971-01-05 Wah Chang Albany Corp Method and apparatus for compacting isostatically metal particles into solid form
US3862286A (en) * 1972-10-10 1975-01-21 Aluminum Co Of America Method of fabricating compacted powdered metal extrusion billets
US3780418A (en) * 1972-10-10 1973-12-25 Aluminum Co Of America Method of fabricating composite multi-metallic billets useful for metal working operations
US3892030A (en) * 1974-04-29 1975-07-01 Us Air Force Method of fabricating a billet from metal preforms and metal powder
US4000235A (en) * 1975-05-13 1976-12-28 National Forge Company Method for molding particulate material into rods
US4077109A (en) * 1976-05-10 1978-03-07 The International Nickel Company, Inc. Hot working of metal powders

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KR850004035A (en) 1985-07-01
DE3473840D1 (en) 1988-10-13
US4565668A (en) 1986-01-21
EP0141350A1 (en) 1985-05-15
DE3338369C1 (en) 1985-09-26
JPS60145303A (en) 1985-07-31
JPS6340843B2 (en) 1988-08-12

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