US3159482A - Method of manufacturing a sintered metal tube - Google Patents

Method of manufacturing a sintered metal tube Download PDF

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US3159482A
US3159482A US91348A US9134861A US3159482A US 3159482 A US3159482 A US 3159482A US 91348 A US91348 A US 91348A US 9134861 A US9134861 A US 9134861A US 3159482 A US3159482 A US 3159482A
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tube
sintering
metal
outer tube
during
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US91348A
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Eudier Michel
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    • 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
    • B22F3/10—Sintering 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

Definitions

  • sintering devices should be designed in such a way that the tubes, while still unsintered, do not break.
  • the tube is first formed by the agglomeration of a metallic powder with a binder, and is then placed in aninclined position, rotated substantiallyabout its axis and heated starting from the lower part of the tube.
  • the invention also includes an apparatus for manufacturing tubes from sintered metal, which comprises an inclined refractory tube for containing a tube formed of a mixture of a metal powder and a binding agent, the inner diameter of the refractory tube being at least 0.5 mm. greater than the outer diameter of the metal powder tube, a motor for rotating the refractory tube about its axis and an annular furnace surrounding the refractory tube and arranged to undergo displacement upwardly along the refractory tube during the sintering process.
  • an apparatus for manufacturing tubes from sintered metal which comprises an inclined refractory tube for containing a tube formed of a mixture of a metal powder and a binding agent, the inner diameter of the refractory tube being at least 0.5 mm. greater than the outer diameter of the metal powder tube, a motor for rotating the refractory tube about its axis and an annular furnace surrounding the refractory tube and arranged to undergo displacement upwardly along the refractory tube during the sintering process.
  • the inclination of the outer tube is preferably such that the angle formed by it with the horizontal plane is between 5 and 30; in this way, the sinter tube is prevented from sliding relative to the outer tube. Moreover, since there is a clearance between the sinter tube and the outer tube and the former rests on the latter substantially along one of its generatrices, the frictional forces between the two tubes are decreased because of the inclination, although for inclinations less than 5 these frictional forces could be sufiicient to produce fracture of the tube into several pieces when the inner sinter tube shrinks.
  • the maximum angle of inclination depends principally on the nature of the surfaces in contact (the sinter tube and the outer tube). If the outer tube is ridged, for example, this maximum'angle of inclination can be increased, since there is less tendency for sliding of the sinter tube relative to the outer tube.
  • the outer diameter of the sinter tube is less than the inner diameter of the outer tube by an amount sufiicient to prevent their coincidence during sintering, and to en able the sinter tube to roll inside the outer tube during the rotation of the latter.
  • the clearance between the two positioned tubes, namely the difference between the two diameters mentioned, should be at least 0.5 mm.
  • the inner tube undergoes shrinkage during sintering and becomes oval shaped if it does not rotate, that is to say, if the outer tube does not transmit its own rotary movement thereto. Because of this rotation, the formation of an oval shape is completely prevented.
  • the speed vof rotation v of the outer tube should be a minimum of the order of l revolution during the period of sintering; since the speed can vary between 10 minutes and one hour, particularly according to the nature of'the sintering powder and temperature chosen, it can be seen that the minimum speed of rotation is of the order of l to 6 revolutions per hour; the maximum value of the speed of rotation is limited only by the resistance to vibration of the sinter tube, but there is no purpose in trying to should be a fraction (not more than half) of the length of the outer tube.
  • t is the duration of sintering (between 10 minutes and an hour).
  • the length of this zone is dependent upon the means being used to produce it and consequently has a minimum value (5 cm. in the case of a movable electric resistance furnace), there are minimum and maximum values for the speed v; the minimum value will be equal to 5 cm. per hour in the case where the furnace is 5 cm. in length; in the same case and with an outer tube of 110 cm. in length, the heating zone may have a maximum length of about 55 cms. and the value of v will be in the region of 330 cur/hour.
  • the reason for producing progressive displacement of the heating zone is that the zone in which the binding material iseliminated (in the part below the sinter zone) is of small dimensions and moves progressively in such a way that, in contrast to methods in which the binding material is eliminated simultaneously over an extended zone in the inner tube, it cannot produce fractures of the tube during sintering. Furthermore, as the zone in which a longitudinal shrinkage of the sinter tube is produced at a given moment corresponds to the sinter zone and does not cover the entire length of the inner tube, fractures are prevented which result when the shrinkage occurs at the same moment on all parts of the tube.
  • the apparatus comprises a tube 1 of stainless or re-' 1 in mesh with a pinion 5 driven by a reduction motor.
  • the speed of rotation of the tube 1 about its axis is in the region of one revolution per minute.
  • a tube 6 which is cm. long is mounted inside the tube 1, which has a length of cm., and the tube 6 is formed by metal powder agglomerated by a binder, for example collodion.
  • This tube may be formed by many different methods, for
  • a clearance of 1 mm. is left between the adjacent walls of tubes 1 and 6 to accommodate the tube 6, which has an outer diameter for example between 5 and 25 mm.
  • a conduit 7 is introduced into the upper end of the tube 1 for supplying a stream ofhydrogen into the latter or, in general, any reducing gas (or a vacuum may be provided in tube 1); the gas is burnt at the lower end of the tube 1.
  • the sintered tube is fully protected during the sintering operation (in particular mechanical protection is providedbythe outer'tube 1) thatis to'say, during'the time at which the tube is the most fragile.
  • the collodion or other binding agent is destroyed by'the heating and the metallic powder forming the tubeGbecomes sintered.
  • the gases formed by destruction of'the'binding agent are evacuated at the same time as'theexcess hydrogen.
  • the invention is not limited by the details of the method described, the expert being able to modify these methods, within thescope of the invention.
  • the nature of the metal comprising the sinter powder and the 'nature of the binding agent may be varied.
  • Such metals are, for example, iron, bronze and'nickel, and the binding agent may be collodion, polyvinyl alcohol in water orgum tragacanth in water.
  • a method of manufacturing a sintered metal tube which comprises forming a mixture of powdered metal and a binding agent into a tubular shape, locating the thus-formedmetal powder tube with a clearance in an outer tube of refractory material disposed at an angle to the horizontal, the clearance between the metal powder tube and the outer tube being sufiicient to prevent their coincidence during sintering, rotating the outer tube about its'l'ongitudinal axis at a speed of rotation corresponding'to 'at'least 'one'revolution during the period of the sintering thereby rolling the powder metal tube inside the outer tube during rotation of the latter tube, and.
  • heating step is *elfected by a heat source which is moved longitudinally along said refractory tube'fromthe lower portion thereof to the upper portion thereof during the period of sintering.

Description

1964- M EUDIER 3, 5 8
METHOD OF MANUFACTURING A SINTERED METAL TUBE Filed Feb. 24, 1961 IN VE N TOE MICHEL E 1/0/52 A TTOENEYS United States Patent 3,159,482 METHOD OF MANUFACTURING A SHQTERED METAL TUBE Michel Earlier, 3 Rue Andrieux, Paris, France Filed Feb. 24, 1961, Ser. No. 91,348 Claims priority, application France Mar. 11, 1960 Claims. (Cl. 75-200) The present invention concerns the manufacture of porous or non-porous tubes, having a density equal to or less than the density of the metal used, by sintering metallic powders.
The manufacture of tubes from sintered metal presents several difficult problems, particularly with regard to preserving the shape of the tube while applying heat during the sintering process.
On the other hand, sintering devices should be designed in such a way that the tubes, while still unsintered, do not break.
According to the method of the present invention, the tube is first formed by the agglomeration of a metallic powder with a binder, and is then placed in aninclined position, rotated substantiallyabout its axis and heated starting from the lower part of the tube.
The invention also includes an apparatus for manufacturing tubes from sintered metal, which comprises an inclined refractory tube for containing a tube formed of a mixture of a metal powder and a binding agent, the inner diameter of the refractory tube being at least 0.5 mm. greater than the outer diameter of the metal powder tube, a motor for rotating the refractory tube about its axis and an annular furnace surrounding the refractory tube and arranged to undergo displacement upwardly along the refractory tube during the sintering process.
The inclination of the outer tube is preferably such that the angle formed by it with the horizontal plane is between 5 and 30; in this way, the sinter tube is prevented from sliding relative to the outer tube. Moreover, since there is a clearance between the sinter tube and the outer tube and the former rests on the latter substantially along one of its generatrices, the frictional forces between the two tubes are decreased because of the inclination, although for inclinations less than 5 these frictional forces could be sufiicient to produce fracture of the tube into several pieces when the inner sinter tube shrinks. The maximum angle of inclination depends principally on the nature of the surfaces in contact (the sinter tube and the outer tube). If the outer tube is ridged, for example, this maximum'angle of inclination can be increased, since there is less tendency for sliding of the sinter tube relative to the outer tube.
The outer diameter of the sinter tube is less than the inner diameter of the outer tube by an amount sufiicient to prevent their coincidence during sintering, and to en able the sinter tube to roll inside the outer tube during the rotation of the latter. The clearance between the two positioned tubes, namely the difference between the two diameters mentioned, should be at least 0.5 mm.
The inner tube undergoes shrinkage during sintering and becomes oval shaped if it does not rotate, that is to say, if the outer tube does not transmit its own rotary movement thereto. Because of this rotation, the formation of an oval shape is completely prevented. The speed vof rotation v of the outer tube should be a minimum of the order of l revolution during the period of sintering; since the speed can vary between 10 minutes and one hour, particularly according to the nature of'the sintering powder and temperature chosen, it can be seen that the minimum speed of rotation is of the order of l to 6 revolutions per hour; the maximum value of the speed of rotation is limited only by the resistance to vibration of the sinter tube, but there is no purpose in trying to should be a fraction (not more than half) of the length of the outer tube. According to the importance of the length of this zone, its speed of displacement v will conform more or less to the formula v=L/ t, where t is the duration of sintering (between 10 minutes and an hour). As the length of this zone is dependent upon the means being used to produce it and consequently has a minimum value (5 cm. in the case of a movable electric resistance furnace), there are minimum and maximum values for the speed v; the minimum value will be equal to 5 cm. per hour in the case where the furnace is 5 cm. in length; in the same case and with an outer tube of 110 cm. in length, the heating zone may have a maximum length of about 55 cms. and the value of v will be in the region of 330 cur/hour.
The reason for producing progressive displacement of the heating zone is that the zone in which the binding material iseliminated (in the part below the sinter zone) is of small dimensions and moves progressively in such a way that, in contrast to methods in which the binding material is eliminated simultaneously over an extended zone in the inner tube, it cannot produce fractures of the tube during sintering. Furthermore, as the zone in which a longitudinal shrinkage of the sinter tube is produced at a given moment corresponds to the sinter zone and does not cover the entire length of the inner tube, fractures are prevented which result when the shrinkage occurs at the same moment on all parts of the tube. I In order that the invention may be more readily understood, the preferred embodiment thereof is described 7 below in conjunction with the accompanying drawing,
which shows an elevational view, partly in section of one form of apparatus for manufacturing tubes.
The apparatus comprises a tube 1 of stainless or re-' 1 in mesh with a pinion 5 driven by a reduction motor.
The speed of rotation of the tube 1 about its axis is in the region of one revolution per minute. A tube 6 which is cm. long is mounted inside the tube 1, which has a length of cm., and the tube 6 is formed by metal powder agglomerated by a binder, for example collodion.
This tube may be formed by many different methods, for
example by centrifugal action and drying or by extruson.
A clearance of 1 mm. is left between the adjacent walls of tubes 1 and 6 to accommodate the tube 6, which has an outer diameter for example between 5 and 25 mm.
When the tube 6 is located inside the tube 1, a conduit 7 is introduced into the upper end of the tube 1 for supplying a stream ofhydrogen into the latter or, in general, any reducing gas (or a vacuum may be provided in tube 1); the gas is burnt at the lower end of the tube 1.
The sintering heating is effected by a furnace 8 initially disposed at the lower end of the tube 1 and provided with driving means of a known type (endless screw for ex to the rotation (the speed of rotation v '=60 revs/hour),
formation-oftheoval shape is completely avoided. Moreover, the sintered tube is fully protected during the sintering operation (in particular mechanical protection is providedbythe outer'tube 1) thatis to'say, during'the time at which the tube is the most fragile.
The speed of displacement'v of the furnaces (length L ofthe furnace=20 cms) "is of the order of 1 metre an hour which corresponds to a duration of sintering of 12 minutes '(the fpitch of the helix described by a point on the region of the sintered'tube situated at the intersection of onegeneratrix of this tube and of the zone of sintering is'thus equal to 1.65 cm.).
During the sintering, the collodion or other binding agent is destroyed by'the heating and the metallic powder forming the tubeGbecomes sintered. The gases formed by destruction of'the'binding agent are evacuated at the same time as'theexcess hydrogen.
'Of course, the invention is not limited by the details of the method described, the expert being able to modify these methods, within thescope of the invention. The nature of the metal comprising the sinter powder and the 'nature of the binding agent may be varied. Such metals are, for example, iron, bronze and'nickel, and the binding agent may be collodion, polyvinyl alcohol in water orgum tragacanth in water.
What'I claim is:
1. A method of manufacturing a sintered metal tube, which comprises forming a mixture of powdered metal and a binding agent into a tubular shape, locating the thus-formedmetal powder tube with a clearance in an outer tube of refractory material disposed at an angle to the horizontal, the clearance between the metal powder tube and the outer tube being sufiicient to prevent their coincidence during sintering, rotating the outer tube about its'l'ongitudinal axis at a speed of rotation corresponding'to 'at'least 'one'revolution during the period of the sintering thereby rolling the powder metal tube inside the outer tube during rotation of the latter tube, and.
supplying'heat to sinter the metal powder tube.
2. A method as claimed in claim 1, in which the heating step is *elfected by a heat source which is moved longitudinally along said refractory tube'fromthe lower portion thereof to the upper portion thereof during the period of sintering.
3. A method as claimed in claim 2, in which said heat source is moved so as to provide an overall sintering time of 10 to minutes.
4. A method as claimed in claim 1, in which the refractory tube is disposed at an inclination of 5 to 30 to the horizontal.
5. A method as claimed in claim 1, in which the sintering temperature is 600 to 1200 C.
6. A method as claimed in claim 1, in which the clearance between the metal powder tube andthe refractory tube is at least 0.5mm.
7. A method as claimed in claim 1, in which the speed of rotation of the refractory tube is up to 5 revolutions per hour.
8. A method as claimed in claim 1, in which a stream of hydrogen or other.reducing'gasis'passed through'the refractory tube during sintering.
9Q A metho'd as claimed in claim 1, in which the binding agent is selected from the group consistingof collodion, polyvinyl alcohol and gum tragacanth.
10. A method as claimed in claim 1, in which the'metal powder is selected from the group consisting of iron,
bronze and nickel.
References Cited in the file of this patent UNITED STATESPATENTS 1,226,470 Coolidge May 15,1917 1,531,666 Laise Mar. 31, 1925 2,372,203 Hensel et al Mar. 27, 1945 2,431,690 Hall et al. Dec. 2, 1947 2,930,098 Emeis Mar. 29, 1960 2,936,505 \Vitucki et a1 May 17, 1960 FOREIGN PATENTS 1,077,511 Germany "Mar..10, 1960 1,237,168 France June 20, 1960 OTHER REFERENCES AEC Document TID 7546, Book 2, November 1957, pp. 532 and 533.

Claims (1)

1. A METHOD OF MANUFACTURING A SINTERED METAL TUBE, WHICH COMPRISES FORMING A MIXTURE OF POWDERED METAL AND A BINDER AGENT INTO A TUBULAR SHAPE, LOCATING THE THUS-FORMED METAL POWDER TUBE WITH A CLEARANCE IN AN OUTER TUBE OF REFRACTORY MATERIAL DISPOSED AT AN ANGLE TO THE HORIZONTAL, THE CLEARANCE BETWEEN THE METAL POWDER TUBE AND THE OUTER TUBE BEING SUFFICIENT TO PREVENT THEIR COINCIDENCE DURING SINTERING, ROTATING THE OUTER TUBE ABOUT ITS LONGITUDINAL AXIS AT A SPEED OF ROTATION CORRESPONDING TO AT LEAST ONE REVOLUTION DURING THE PERIOD OF THE SINTERING THEREBY ROLLING THE POWDER METAL TUBE INSIDE THE OUTER TUBE DURING ROTATION OF THE LATTER TUBE, AND SUPPLYING HEAT TO SINTER THE METAL POWDER TUBE.
US91348A 1960-03-11 1961-02-24 Method of manufacturing a sintered metal tube Expired - Lifetime US3159482A (en)

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FR820988A FR1259408A (en) 1960-03-11 1960-03-11 Process and installation of sintering for obtaining metal tubes

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BE (1) BE600608A (en)
CH (1) CH373247A (en)
DE (1) DE1289625B (en)
FR (1) FR1259408A (en)
GB (1) GB937573A (en)
LU (1) LU39834A1 (en)
NL (2) NL124042C (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3678567A (en) * 1970-06-18 1972-07-25 Int Nickel Co Production of clad metal articles
CN103231040A (en) * 2013-04-27 2013-08-07 暨南大学 Semisolid extrusion and thixomolding mould and method for degradable magnesium alloy micro cautery

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1164342B (en) * 1982-08-14 1987-04-08 Mtu Muenchen Gmbh PROCEDURE FOR JOINING IMMEDIATELY DISCRETE COMPONENTS, AS WELL AS HEAT EXCHANGER BLOCK, PRODUCED ACCORDING TO THIS PROCEDURE

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1226470A (en) * 1915-02-20 1917-05-15 Gen Electric Refractory-metal tube.
US1531666A (en) * 1922-06-12 1925-03-31 Clemens A Laise Refractory metallic body of high density and process for making the same
US2372203A (en) * 1943-09-06 1945-03-27 Mallory & Co Inc P R Sintered metal article and process of making
US2431690A (en) * 1945-02-21 1947-12-02 Westinghouse Electric Corp Consolidation of metal powder
DE1077511B (en) * 1952-10-01 1960-03-10 Plansee Metallwerk Process for sintering molded bodies produced by powder metallurgy
US2930098A (en) * 1954-06-30 1960-03-29 Siemens Ag Production of sintered bodies from powdered crystalline materials
US2936505A (en) * 1958-10-16 1960-05-17 Curtiss Wright Corp Method and apparatus for forming refractory articles
FR1237168A (en) * 1959-06-10 1960-07-29 Metallurgie Francaise Apparatus for manufacturing bars or wires by sintering

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL89230C (en) * 1952-12-17 1900-01-01
DE1056840B (en) * 1953-02-14 1959-05-06 Siemens Ag Method for distributing foreign matter components in semiconductor rods by a crucible-free zone melting method

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1226470A (en) * 1915-02-20 1917-05-15 Gen Electric Refractory-metal tube.
US1531666A (en) * 1922-06-12 1925-03-31 Clemens A Laise Refractory metallic body of high density and process for making the same
US2372203A (en) * 1943-09-06 1945-03-27 Mallory & Co Inc P R Sintered metal article and process of making
US2431690A (en) * 1945-02-21 1947-12-02 Westinghouse Electric Corp Consolidation of metal powder
DE1077511B (en) * 1952-10-01 1960-03-10 Plansee Metallwerk Process for sintering molded bodies produced by powder metallurgy
US2930098A (en) * 1954-06-30 1960-03-29 Siemens Ag Production of sintered bodies from powdered crystalline materials
US2936505A (en) * 1958-10-16 1960-05-17 Curtiss Wright Corp Method and apparatus for forming refractory articles
FR1237168A (en) * 1959-06-10 1960-07-29 Metallurgie Francaise Apparatus for manufacturing bars or wires by sintering

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3678567A (en) * 1970-06-18 1972-07-25 Int Nickel Co Production of clad metal articles
CN103231040A (en) * 2013-04-27 2013-08-07 暨南大学 Semisolid extrusion and thixomolding mould and method for degradable magnesium alloy micro cautery
CN103231040B (en) * 2013-04-27 2015-09-09 暨南大学 The micro cautery of degradable magnesium alloy microcapillary and method

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FR1259408A (en) 1961-04-28
LU39834A1 (en) 1961-04-25
CH373247A (en) 1963-11-15
NL262164A (en)
BE600608A (en) 1961-06-16
GB937573A (en) 1963-09-25
NL124042C (en)
DE1289625B (en) 1969-02-20

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