EP0141349B1 - Process for manufacturing tubes by powder metallurgy and tubular work pieces obtained thereby (semi-products) - Google Patents

Process for manufacturing tubes by powder metallurgy and tubular work pieces obtained thereby (semi-products) Download PDF

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Publication number
EP0141349B1
EP0141349B1 EP84112604A EP84112604A EP0141349B1 EP 0141349 B1 EP0141349 B1 EP 0141349B1 EP 84112604 A EP84112604 A EP 84112604A EP 84112604 A EP84112604 A EP 84112604A EP 0141349 B1 EP0141349 B1 EP 0141349B1
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European Patent Office
Prior art keywords
tube
bulge
inner tube
powder
tube surface
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Expired
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EP84112604A
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German (de)
French (fr)
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EP0141349A1 (en
Inventor
Christer Aslund
Claes Tornberg
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Nyby Uddeholm Powder AB
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Nyby Uddeholm Powder AB
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Publication of EP0141349A1 publication Critical patent/EP0141349A1/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25C—HAND-HELD NAILING OR STAPLING TOOLS; MANUALLY OPERATED PORTABLE STAPLING TOOLS
    • B25C1/00—Hand-held nailing tools; Nail feeding devices
    • B25C1/06—Hand-held nailing tools; Nail feeding devices operated by electric power
    • 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
    • B22F3/1258—Container manufacturing
    • 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
    • B22F3/20—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces by extruding

Definitions

  • the invention relates to a method for the powder-metallurgical production of pipes, in which powders of metal and / or metal alloys are filled into a thin-walled capsule consisting of an inner tube jacket and an outer tube jacket and a base, the capsule then on its side opposite the base with an annular cover sealed and exposed to a cold isostatic pressure, whereby the powder is compressed or compressed within the capsule, so that a solid or dimensionally stable tube blank is formed, which is then extruded under heat.
  • the object of the present invention is to avoid such a crack formation when the tube blank is heated to the hot working temperature.
  • the bulge according to the invention can compensate or neutralize thermal stresses, the bulge or bulges being formed at the locations of maximum thermal stresses, that is to say preferably at the end regions of the inner tube or inner tube jacket.
  • the bulges preferably extend radially outward and are formed by means of rollers or rollers or the like, it being possible for both male and female dies to be used.
  • the bulges have a “soft or flat” shape, particularly in the area of the transitions from the bulge to the inner tube or inner tube jacket.
  • the cross section of the bulge is thus approximately trough-shaped, the transition radii being approximately in the order of magnitude of the radius of the inner tube jacket. The formation of wrinkles must be avoided in any case.
  • the bulges allow the inner tube or inner tube shell to be easily stretched or stretched when the tube blank or compact is heated to the hot working temperature, so that the inner tube shell is smoothed.
  • a preferred embodiment of a tube blank or compact formed and used according to the invention is briefly explained below with reference to the attached drawing. This shows a cross section of a pipe blank or compact before hot machining. Mean
  • a radially outwardly extending bulge 15, 16 is formed, which allows thermal expansion of the inner tube when the tubular capsule 10 is heated to the hot working temperature, in such a way that the inner tube is smoothed jacket 12 takes place.
  • two or more bulges corresponding to the bulges 15, 16 extending over the circumference of the inner tube or inner tube shell 12 can be arranged at the front ends.
  • the bulges 15, 16 are relatively flat in cross section, ie the transition radii are relatively large and move in the order of magnitude of the radius of the inner tube shell 12.
  • the pipe blank or compact 10 heated to the hot working temperature with the smoothed inner pipe jacket 12 can then be pressed in a conventional manner to the final pipe string.
  • the depth and the transition radii r i , r 2 and r 3 depend both on the dimension of the tube blank or compact 10, the powder material used, the material of the inner tube jacket 12 and outer tube jacket 11 and the hot working temperature.
  • the base radius r 2 is preferably approximately twice as large as the transition radii r, and r 2 in the transition region between the bulge and the inner tube.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Powder Metallurgy (AREA)
  • Shaping Metal By Deep-Drawing, Or The Like (AREA)
  • Drilling And Boring (AREA)

Description

Die Erfindung betrifft ein Verfahren zur pulvermetallurgischen Herstellung von Rohren, bei dem Pulver aus Metall und/oder Metall-Legierungen in eine dünnwandige Kapsel, bestehend aus Innenrohrmantel und Aussenrohrmantel sowie einem Boden eingefüllt, die Kapsel anschliessend an ihrer dem Boden gegenüberliegenden Seite mit einem ringförmigen Deckel verschlossen und einem kaltisostatischen Druck ausgesetzt wird, wodurch eine Verdichtung bzw. Verpressung des Pulvers innerhalb der Kapsel erfolgt, so dass ein fester bzw. formbeständiger Rohrrohling entsteht, der dann unter Wärme stranggepresst wird.The invention relates to a method for the powder-metallurgical production of pipes, in which powders of metal and / or metal alloys are filled into a thin-walled capsule consisting of an inner tube jacket and an outer tube jacket and a base, the capsule then on its side opposite the base with an annular cover sealed and exposed to a cold isostatic pressure, whereby the powder is compressed or compressed within the capsule, so that a solid or dimensionally stable tube blank is formed, which is then extruded under heat.

Ein derartiges Verfahren ist allgemein bekannt. Es hat sich jedoch gezeigt, dass sehr häufig vor allem am Innenrohr bzw. Innenrohrmantel wärmespannungs-bedingte Risse auftreten, und zwar insbesondere an den beiden stirnseitigen Endbereichen, d. h. nahe dem Kapselboden und/oder Kapseldeckel. Die Risse können sich über den gesamten Umfang des Innenrohres bzw. Innenrohrmantels erstrecken oder nur über einen Teil desselben. Dies hängt von dem Ausmass der Wärmespannungen ab.Such a method is generally known. However, it has been shown that cracks due to thermal stress occur very often, particularly on the inner tube or inner tube jacket, in particular on the two end regions, ie. H. near the capsule bottom and / or capsule lid. The cracks can extend over the entire circumference of the inner tube or inner tube shell or only over a part of the same. This depends on the extent of the thermal stress.

Es wurde festgestellt, dass die erwähnte Rissbildung ihre Ursache in einer ungleichmässigen Erwärmung der Rohr-Kapsel auf die Warmbearbeitungstemperatur hat. Eine solche ungleichmässige Erwärmung tritt insbesondere dann auf, wenn in grossen Öfen und mit relativ grossen Rohr-Rohlingen bzw. -Presslingen gearbeitet wird. Man stellte beispielsweise fest, dass die Wärmespannungen zu Dehnungen insbesondere des Innenrohres bzw. Innenrohrmantels führen können, die in der Grössenordnung von 0,5 bis 1% der Länge des Rohr-Rohlings bzw. -Presslings liegen.It was found that the above-mentioned cracking was caused by the tube capsule heating up unevenly to the hot working temperature. Such uneven heating occurs in particular when working in large furnaces and with relatively large pipe blanks or compacts. It was found, for example, that the thermal stresses can lead to expansions, in particular of the inner tube or inner tube shell, which are of the order of magnitude of 0.5 to 1% of the length of the tube blank or compact.

Der vorliegenden Erfindung liegt nun die Aufgabe zugrunde, eine derartige Rissbildung bei Erwärmung des Rohr-Rohlings auf die Warmbearbeitungstemperatur zu vermeiden.The object of the present invention is to avoid such a crack formation when the tube blank is heated to the hot working temperature.

Diese Aufgabe wird erfindungsgemäss in überraschend einfacher Weise durch die kennzeichnenden Massnahmen des Patentanspruches 1 gelöst, wobei die in den Unteransprüchen beschriebenen verfahrenstechnischen und formgebenden Merkmale sich als besonders vorteilhaft herausgestellt haben.According to the invention, this object is achieved in a surprisingly simple manner by the characterizing measures of patent claim 1, the procedural and shaping features described in the subclaims having proven to be particularly advantageous.

Durch die erfindungsgemässe Ausbuchtung können Wärmespannungen kompensiert bzw. neutralisiert werden, wobei die Ausbuchtung bzw. Ausbuchtungen an den Stellen maximaler Wärmespannungen, also vorzugsweise an den stirnseitigen Endbereichen des Innenrohres bzw. Innenrohrmantels ausgebildet werden.The bulge according to the invention can compensate or neutralize thermal stresses, the bulge or bulges being formed at the locations of maximum thermal stresses, that is to say preferably at the end regions of the inner tube or inner tube jacket.

Die Grösse der Ausbuchtung bzw. Ausbuchtungen hängt von der Abmessung des Rohr-Rohlings und natürlich der Warmbearbeitungstemperatur ab. Die Ausbuchtung bzw. Ausbuchtungen müssen so bemessen sein, dass sich das Innenrohr bzw. der Innenrohrmantel bei Erwärmung des Rohr-Rohlings bzw. -Presslings auf die Warmbearbeitungstemperatur praktisch vollständig glättet. Die durch die Temperaturunterschiede bedingten Innenrohrdehnungen bzw. -verlängerungen können von vornherein berechnet werden auf der Basis der nachstehenden Gleichung:

Figure imgb0001
wobei

  • AT die Temperaturänderung in °C
  • L die Länge des Rohr-Rohlings bzw. -Presslings in mm und
  • a der Wärmeausdehnungskoeffizient bedeuten.
The size of the bulge or bulges depends on the dimension of the tube blank and, of course, the hot working temperature. The bulge or bulges must be dimensioned such that the inner tube or the inner tube jacket practically completely smoothes out when the tube blank or compact is heated to the hot working temperature. The inner pipe expansions or extensions caused by the temperature differences can be calculated from the outset based on the following equation:
Figure imgb0001
 in which
  • AT is the temperature change in ° C
  • L the length of the pipe blank or compact in mm and
  • a mean the coefficient of thermal expansion.

Vorzugsweise erstrecken sich die Ausbuchtungen radial nach aussen und werden mittels Rollen oder Walzen oder dergleichen eingeformt, wobei sowohl Patrizen als auch Matrizen zur Anwendung gelangen können.The bulges preferably extend radially outward and are formed by means of rollers or rollers or the like, it being possible for both male and female dies to be used.

Von ganz wesentlicher Bedeutung ist, dass die Ausbuchtungen eine «weich bzw. flach verlaufende» Form, insbesondere im Bereich der Übergänge von der Ausbuchtung zum Innenrohr bzw. Innenrohrmantel, haben. Der Querschnitt der Ausbuchtung ist also etwa muldenförmig, wobei die Übergangsradien etwa in der Grössenordnung des Radius des Innenrohrmantels liegen. Die Ausbildung von Falten muss auf jeden Fall vermieden werden.It is very important that the bulges have a “soft or flat” shape, particularly in the area of the transitions from the bulge to the inner tube or inner tube jacket. The cross section of the bulge is thus approximately trough-shaped, the transition radii being approximately in the order of magnitude of the radius of the inner tube jacket. The formation of wrinkles must be avoided in any case.

Wie dargelegt, erlauben die Ausbuchtungen eine problemlose Streckung bzw. Dehnung des Innenrohres bzw. Innenrohrmantels bei Erwärmung des Rohr-Rohlings bzw. -Presslings auf die Warmbearbeitungstemperatur, so dass eine Glättung des Innenrohrmantels stattfindet.As explained, the bulges allow the inner tube or inner tube shell to be easily stretched or stretched when the tube blank or compact is heated to the hot working temperature, so that the inner tube shell is smoothed.

Bei besonders grossen Rohr-Rohlingen ist es zweckmässig, vor der Ausbildung der Ausbuchtungen die entsprechenden Stellen, z. B. die stirnseitigen Endbereiche des Innenrohres, zu glühen und von der sich ausbildenden Oxydschicht zu befreien.In the case of particularly large pipe blanks, it is expedient to have the appropriate places, for. B. the front end areas of the inner tube to glow and free of the oxide layer being formed.

Nachstehend wird eine bevorzugte Ausführungsform eines erfindungsgemäss ausgebildeten und verwendeten Rohr-Rohlings bzw. -Presslings anhand der beigefügten Zeichnung kurz erläutert. Diese zeigt einen Rohr-Rohling bzw. -Pressling vor der Warmbearbeitung im Querschnitt. Dabei bedeuten

Figure imgb0002
A preferred embodiment of a tube blank or compact formed and used according to the invention is briefly explained below with reference to the attached drawing. This shows a cross section of a pipe blank or compact before hot machining. Mean
Figure imgb0002

An den stirnseitigen Enden des Innenrohres bzw. Innenrohrmantels 12 ist jeweils eine sich radial nach aussen erstreckende Ausbuchtung 15, 16 ausgebildet, die eine Wärmedehnung des Innenrohres bei Erwärmung der rohrförmigen Kapsel 10 auf die Warmbearbeitungstemperatur erlaubt, derart, dass eine Glättung des Innenrohrmantels 12 stattfindet. Bei etwas länger und grösser dimensionierten Rohrkapseln 10 können an den stirnseitigen Enden jeweils zwei oder mehr sich über den Umfang des Innenrohres bzw. Innenrohrmantels 12 erstreckende Ausbuchtungen entsprechend den Ausbuchtungen 15, 16 angeordnet sein. Wie die anliegende Zeichnung noch erkennen lässt, verlaufen die Ausbuchtungen 15, 16 im Querschnitt relativ flach, d. h. die Übergangsradien sind relativ gross und bewegen sich in der Grössenordnung des Radius des Innenrohrmantels 12.At the front ends of the inner tube or inner tube shell 12, a radially outwardly extending bulge 15, 16 is formed, which allows thermal expansion of the inner tube when the tubular capsule 10 is heated to the hot working temperature, in such a way that the inner tube is smoothed jacket 12 takes place. In the case of tube capsules 10 of somewhat longer and larger dimensions, two or more bulges corresponding to the bulges 15, 16 extending over the circumference of the inner tube or inner tube shell 12 can be arranged at the front ends. As can be seen from the attached drawing, the bulges 15, 16 are relatively flat in cross section, ie the transition radii are relatively large and move in the order of magnitude of the radius of the inner tube shell 12.

Der auf die Warmbearbeitungstemperatur erwärmte Rohr-Rohling bzw. -Pressling 10 mit geglättetem Innenrohrmantel 12 kann dann in herkömmlicher Weise zu dem endgültigen Rohrstrang gepresst werden.The pipe blank or compact 10 heated to the hot working temperature with the smoothed inner pipe jacket 12 can then be pressed in a conventional manner to the final pipe string.

Die Tiefe und die Übergangsradien ri, r2 und r3 hängen sowohl von der Abmessung des Rohr-Rohlings bzw. -Presslings 10, des verwendeten Pulvermaterials, des Materials von Innenrohrmantel 12 und Aussenrohrmantel 11 sowie der Warmbearbeitungstemperatur ab. Vorzugsweise ist der Sohlen-Radius r2 etwa doppelt so gross wie die Übergangsradien r, und r2 im Übergangsbereich zwischen Ausbuchtung und Innenrohr.The depth and the transition radii r i , r 2 and r 3 depend both on the dimension of the tube blank or compact 10, the powder material used, the material of the inner tube jacket 12 and outer tube jacket 11 and the hot working temperature. The base radius r 2 is preferably approximately twice as large as the transition radii r, and r 2 in the transition region between the bulge and the inner tube.

Sämtliche in den Unterlagen offenbarten Merkmale werden als erfindungswesentlich beansprucht, soweit sie einzeln oder in Kombination gegenüber dem Stand der Technik neu sind.All features disclosed in the documents are claimed as essential to the invention, insofar as they are new compared to the prior art, individually or in combination.

Claims (5)

1. A process for the powder-metallurgical manufacture of tubes, in which powder of metal and/ or metal alloy is loaded into a thin-walled box consisting of an inner circumferential tube surface and an outer circumferential tube surface and a base, the box then being closed at its opposite side from the base with an annular lid and exposed to cold isostatic pressure, compression or moulding of the powder thereby being effected inside the box so that a compact or dimensionally stable tube blank is obtained, which is then extruded under heat, characterized in that before the heat treatment the inner tube is provided at at least one end area with at least one bulge (15 or 16) gentle or shallow in form and extending over the circumference, a gentle transition being formed between the bulge (15 or 16) and the rest of the inner tube.
2. A process according to claim 1, characterized in that a bulge (15, 16) extending radially outwards is formed by means of rollers, rolls, or the like at the end areas of the inner tube or inner circumferential tube surface (12).
3. A process according to claim 1 or claim 2, characterized in that at each end area of the inner tube or inner circumferential tube surface (12) at least one bulge (15, 16) is formed extending over the circumference.
4. A process according to any one of claims 1 to 3, characterized in that before formation of the bulge or bulges (15, 16) the tube blank (10) is annealed at least in the area(s) where the former is/are arranged and the oxide layer formed is then removed.
5. A tube blank for the powder-metallurgical manufacture of tubes, which blank is manufactured by the process according to any one or more of claims 1 to 4 from a thin-walled box consisting of an inner circumferential tube surface (12), an outer circumferential tube surface (11) and an annular base (13) and lid (14), into which powder (17) of metal and/or metal alloy is loaded, characterized in that the inner tube or inner circumferential tube surface (12) comprises, at at least one end area, at least one bulge (15) or (16) extending over the circumference and gentle or shallow in form, a gentle transition with correspondingly large transition radii (rl, r3) being formed between the bulge (15 or 16) and the rest of the inner tube or inner circumferential tube surface (12).
EP84112604A 1983-10-21 1984-10-18 Process for manufacturing tubes by powder metallurgy and tubular work pieces obtained thereby (semi-products) Expired EP0141349B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3338367A DE3338367C1 (en) 1983-10-21 1983-10-21 Process for the powder metallurgical production of pipes and pipe bolts (semi-finished products)
DE3338367 1983-10-21

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EP0141349A1 EP0141349A1 (en) 1985-05-15
EP0141349B1 true EP0141349B1 (en) 1987-10-07

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EP (1) EP0141349B1 (en)
JP (1) JPS60169504A (en)
KR (2) KR890004603B1 (en)
BR (1) BR8405321A (en)
CA (1) CA1228707A (en)
DE (2) DE3338367C1 (en)
ES (1) ES8600986A1 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3520910C2 (en) 1985-06-11 1987-04-02 Avesta Nyby Powder AB, Torshälla Process for the production of extrusion billets, for the powder metallurgical production of tubes
FI100422B (en) * 1994-07-11 1997-11-28 Metso Paper Inc Preparation of roller
JP6303521B2 (en) 2014-01-17 2018-04-04 株式会社ダイヤメット Rotating body, rotating body material, and manufacturing method of rotating body
KR102251808B1 (en) * 2018-08-17 2021-05-20 박성일 Trigger type hand piece

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3009916C2 (en) * 1980-03-14 1985-10-10 Nyby Uddeholm AB, Torshälla Extruded billets for the powder metallurgical production of pipes and processes for their production
FR2492291A1 (en) * 1980-10-22 1982-04-23 Uk I Sp Container for hot extrusion of metal powder - with flow-modifying profiling element(s) to improve prod. yield

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CA1228707A (en) 1987-11-03
ES536956A0 (en) 1985-11-01
KR850004036A (en) 1985-07-01
DE3338367C1 (en) 1985-09-26
KR890004604B1 (en) 1989-11-20
BR8405321A (en) 1985-09-03
KR890003494A (en) 1989-04-15
DE3466656D1 (en) 1987-11-12
KR890004603B1 (en) 1989-11-20
ES8600986A1 (en) 1985-11-01
EP0141349A1 (en) 1985-05-15
JPH0515763B2 (en) 1993-03-02
JPS60169504A (en) 1985-09-03

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