US3615382A - Production of tubular products from metallic powders - Google Patents

Production of tubular products from metallic powders Download PDF

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Publication number
US3615382A
US3615382A US756222A US3615382DA US3615382A US 3615382 A US3615382 A US 3615382A US 756222 A US756222 A US 756222A US 3615382D A US3615382D A US 3615382DA US 3615382 A US3615382 A US 3615382A
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Prior art keywords
powder
mass
tubular
mold
set forth
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US756222A
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English (en)
Inventor
Charles E Manilla
Franklin C Kelly
Richard H Hanewald
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Huntington Alloys Corp
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International Nickel Co Inc
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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
    • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
    • B22F5/10—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of articles with cavities or holes, not otherwise provided for in the preceding subgroups
    • B22F5/106—Tube or ring forms
    • 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
    • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
    • B22F5/10—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of articles with cavities or holes, not otherwise provided for in the preceding subgroups
    • 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
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • 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
    • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy

Definitions

  • Tubular-shaped powder metallurgical compacts are made by process comprising subjecting a mass of metallic powder confined in a tubular cavity to pressure directed outwardly from the interior of the cavity and progressing continuously from one end of the mass to the other.
  • the present invention relates to powder metallurgy and more particularly to powder metallurgical processes for producing tubular-shaped products and to apparatus for producing powder metallurgical compacts.
  • powder metallurgical processes comprising pressing metallic powders together at room temperature with sufficient pressure to obtain cohesion of the particles and thereby provide a compact having sufficient strength to retain its shape when the pressure is released. Frequently the compact is sintered after pressing in.order to obtain improved density, uniformity and strength in the compact. In some instances it is desirable to use sintered compacts as metal stock for making wrought products. It is also known that powder metallurgical processes frequently enable obtaining a number of economic advantages such 'as elimination of needs for melting and casting metals into ingots and working ingots down to sizes near those required for making the finished articles.
  • short tubular compacts e.g., hollow cylindrical compacts having length-to-wall thickness ratios (L:T ratios) up to about 1:1
  • L:T ratios length-to-wall thickness ratios
  • the invention also contemplates a process for production of compacted and sintered tubular products and a process for producing tubing by compaction, sintering and drawing.
  • Another object of the invention is to provide apparatus for making metallic powder compacts.
  • FIGS 1 through 3 depict, in longitudinal partial cross section, stages of an illustrative process in accordance with the invention and an embodiment of apparatus in accordance with the invention;
  • FIG. 4 shows a perspective view of a tubular-shaped powder metallurgical compact produced in accordance with the invention
  • FIGS. 5 through 7 illustrate additional embodiments of powder compaction apparatus in accordance with the invention.
  • FIG. 8 depicts in cross section a process step of drawing a compact into a tube.
  • the present invention contemplates a process for compacting a mass of metallic powder to a hollow tubular shape comprising filling a tubular cavity with a mass of metallic powder, thereby providing a tubular mass having an inner tubular surface and an external tubular surface, and then expanding the cross-sectional areas enclosed by the internal tubular surface continuously and progressively in a direction from one end of the mass to the other end of the mass while maintaining essentially constant the cross-sectional areas enclosed by the outer tubular surface and also maintaining the length of the powder mass essentially constant, to thereby compress and densify the powder mass and reduce the wall thickness thereof to produce a tubular compact.
  • a tapered mandrel is drawn small end first through the powder while it is confined in a mold so that compressive forces which are created by passage of the mandrel compact the powder between the mandrel and the inside surface of the mold.
  • the compact sometimes referred to as green compact, is usually sintered to obtain greater density and strength and can then be hot and/or cold worked into wrought products.
  • full density seamless tubing is made by powder compaction in accordance with the invention by sintering the green compact and cold forming the sintered compact using conventional tube forming apparatus, e.g., tube reducing and tube drawing.
  • the compact can be sintered in the mold in which it is made, in which event the sintering shrinkage will enable easy removal of the compact from the mold, or the compact can be taken out of the mold before sintering.
  • the mold split longitudinally into two or more parts so that the mold can be opened after compaction.
  • a removable liner is provided in the mold.
  • the invention is generally satisfactory for compacting most metallic powder mixtures that are compactible at room temperature by other methods.
  • the invention is particularly satisfactory for compacting ductile metal powders, such as nickel powder, cobalt powder, iron powder, copper powder, aluminum powder, magnesium powder, powders of nickel-copper alloys and powders of ductile nickel-chromium alloys, e.g., alloys containing I percent to 20 percent chromium with balance essentially nickel, and also powders and powder mixtures of metals and alloys having similar ductility characteristics.
  • the metallic powder can comprise metal characteristics.
  • the metallic powder can comprise metal oxides and other metallic compounds including thorium oxide, aluminum oxide, magnesium oxide, silicon carbide and tungsten carbide, e.g., a ductile metallic powder mixture can contain small amounts up to I percent of metallic compounds with the balance being essentially ductile metal powder, e.g., one or more ductile metal powders in proportions totaling at least 90 percent of the mixture. All compositional percentages set forth herein are by weight. Average particle sizes of powders compacted by the present process are usually from about 0.01 micron, or less, to about 200 microns, advantageously, about 1 micron to about 50 microns.
  • the invention is particularly successful in providing accurately dimensioned and uniformly dense compaction of powder into tubular forms having high L:T ratios of about 5:1 and greater, e.g., 250:1 and 350:1.
  • the invention also has advantages of enabling practical production of very long tubular compacts, e.g., compacts 7 feet or feet or more in length.
  • the range of wall thicknesses which can be compacted satisfactorily of course depends somewhat on the characteristics of the powder, as will be understood by those in the art. Generally, when working with ductile metallic powders the process produces good uniform and dense compaction in cylindrical tubes of uniform annular wall thickness sizes ranging from about 0.375 inch to about 1.0 inch.
  • the invention can be employed for production of tubular compacts with other cross-sectional shapes, e.g., elliptical, rectangular, hexagonal and square configurations. It is to be especially noted that the invention provides for compaction between rigid surfaces and thus enables close control over dimensional tolerances.
  • FIGS. 1, 2 and 3 illustrate compaction of metal powder by a process according to the invention using apparatus comprising hollow cylindrical mold assembly 10, cylindrical core 11, forwardly tapered frustoconical mandrel l2 and sizing bar 13.
  • the mold assembly comprises mold shells l4 and I5, forward-end expansible seal 16, forward-end retainer clamp 17, rearward-end expansible seal I8 and rearward-end retainer clamp 19.
  • the transverse cross sections, i.e., cross sections perpendicular to the length of core II, of the core, mandrel and sizing bar are circular and the transverse cross sections of the mold assembly components are annular.
  • Shells l4 and 15 are mated along the plane which passes through the longitudinal axis of core 11 and is perpendicular to the drawing. Thus the mated shells form an annular cylinder.
  • FIG. I shows the mold assembly with the rearward seal and retainer clamp removed to enable filling the mold and with the core held in position by locator pins 20 and 21.
  • the expansible seals are of rubber. Alternatively, other resilient materials, such as silicone rubber compounds, can be used for the seals.
  • Tubular cavity 22, which is formed by inside face 23 of the mold shells and by core surface 24 and which is closed at one end by seal 16, (the other end being defined by the rearward ends of shells l4 and 15) is filled with powder 25.
  • the mold can be rapped, tamped, thumped or vibrated, e.g., vibrated by vibrator 26, to obtain advantageously uniform packing of the powder.
  • the locator pins are removed and the cavity is closed with rearward-end flexible seal 18 and rearward-end retainer clamp 19 as illustrated in FIG. 2.
  • the mold core 11 is pulled forwardly and can also be rotated, as indicated by arrows on the mandrel in FIGS. 2 and 3, by pulling and rotating means 27. In doing so, the tapered mandrel attached to the core is also rotated and is pulled into the mold cavity, thereby continuously and progressively applying outwardly and forwardly directed pressure on the powder and compacting the powder as illustrated in FIG. 2.
  • FIG. 2 shows that the transverse cross sections of concave, interior, tube surface 28 are enlarged during passage of the mandrel through the mold while the transverse cross sections of convex, exterior, tube surface 29 are maintained essentially constant during movement of the mandrel through the mold.
  • the mold shells and the mandrel are very rigid, being made of stiff metals such as high-strength steel, and thus undergo only very slight or no distortion during the process. Also, the length of the mass remains essentially constant inasmuch as the seals are rigidly supported by the retainers, which also bind together shells l4 and I5. Fig.
  • FIG. 3 shows mold 10 with the mandrel having passed completely through and with the sizing bar moving through the mold so as to more precisely fonn the powder mass to the desired configuration.
  • the sizing bar is of uniform circular cross section with the diameter about the same as, or about 0.010 inch less than, the maximum diameter of the mandrel.
  • FIGS. 5 and 6 show expansible sleeve 31 around mandrel 12 in mold assembly I0 and with liner 32 in the mold.
  • the expansible sleeve can be a split sleeve of a rigid material, such as spring steel or stiff resilient plastic, e.g., sleeve 31 is a split sleeve made of spring steel, that will closely conform to the surface of the mandrel when it passes through the sleeve. As illustrated in FIG. 6, sleeve 31 is longitudinally split at 33 and liner 32 is longitudinally split at 34. The expansible sleeve is initially around the core rod and remains held in place by the expansible seals, thus being disposed successively around the core, the mandrel and the sizing bar while these three components are pulled through the mold.
  • Such an expansible sleeve affords advantages of eliminating friction between the powder and the mandrel and enables lubrication of the mandrel with protection of the powder from contamination by the lubricant. in addition to providing advantages of decreased power requirements through savings in frictional losses the expansible sleeve also serves as a centering device that aids in maintaining concentricity. Furthermore, the expansible sleeve feature enables producing with the same mandrel a variety of compacts having different interior dimensions. For this object the apparatus is provided with a number of interchangeable expansible sleeves which are of different thicknesses, and which can also differ in exterior configuration, and the sleeves are interchanged according to the interior size and/or shape that is to be imparted to the compact.
  • centering contactors e.g., vanes or pins
  • FIG. 7 shows centering vanes 35, 36 and 37 attached to core 11 and in longitudinally slideable contact with shells 14 and 15 in mold assembly 10, which is illustrated without the powder.
  • Vanes 35, 36 and 37 are disposed radially at angles of 120 from each other around the core.
  • Expansible seal 38 which closes the forward end of the mold is penetrable by the contactors, e.g., seal 38 is made of a soft resilient material such as soft rubber.
  • the centering contactors slide forwardly along the mold wall when the core is drawn through the mold and thus the contactors guide the core and the mandrel accurately through the center of the mold.
  • the contactors slice through penetrable expansible seal 38.
  • the leading portions of the contactors can be provided with hard and sharp cutting edges. The penetrable seal is held in place, during compaction, by retainer ring 39 and is usually replaced after each use of the mold.
  • ultrasonic vibrations can be applied to the mandrel in order to reduce friction losses, decrease power requirements and aid in insuring a smooth, chatter-free inside surface.
  • FIG. 8 illustrates cold drawing of sintered powder compact 40 through die 41 so as to reduce the diameter and wall thickness of the tubular form and also densify the compacted and sintered metal to essentially full density metal in drawn tube portion 42.
  • the mandrel has a forward taper such that the transverse cross-sectional area of the forward end is less than that of the rearward end.
  • the forward taper is thus a longitudinally oblique slope.
  • Average forward slope (or taper) of the mandrel surface is usually at least about 0.04 inch per foot (in./ft.) and not greater than about 1.25 in./ft., i.e., a forward slope of about 0.33 percent to about 10.4 percent.
  • the forward slope e.g., the mandrel taper, along which pressure is applied be about 0.04 in./ft. to about 0.375 in./ft., in order to obtain advantages of uniformly dense compaction, low friction, rapid production and maximum utilization of available power.
  • the wall thickness of the powder mass is usually reduced about 10 percent to about 40 percent, advantageously 20 percent to about 30 percent, for obtaining particularly good strength and density in the green compact.
  • Expansion of the tubular interior should be sufficient to exert the equivalent of at least about 10,000 p.s.i. outward pressure at the interior of the compact.
  • the process progressively applies about 30,000 p.s.i., or higher, outward pressure to obtain advantageously high dense compaction of strong ductile powders, e.g., carbonyl nickel powder.
  • strong ductile powders e.g., carbonyl nickel powder.
  • Use of a tapered mandrel in expanding the cross sections of the internal surface of the tubular mass to thereby compact the powder provides advantageously good close control over the amount, rate and progress of compaction of the powder and provides good interparticle movement that is beneficial to obtaining dense and uniform compaction.
  • Rate of movement of the mandrel through the powder during compaction can be up to about 30 feet per minute, (ft./rnin.), e.g., about 5 ftJmin.
  • the forward progression of the compacting pressure is applied in the present process through the relative movement of the compacting surface in relation to the tubular mass of powder. Accordingly, the process can also be performed with the sloped compacting surface being held in longitudinally fixed position and with the mold containing the powder mass being moved toward the rearward end of the compacting surface. Moreover, when the sloped compacting surface is entirely of circular transverse cross section, e.g., the curved surface of a frustum of a right cone, either the compacting tool or the powder mass or both can be rotated. For obtaining accurate progress of the compacting tool and for maintaining longitudinally straight alignment of the compacting tool it is highly beneficial to maintain tension on the compacting tool while progressively compacting the powder.
  • the expansion is accomplished with pressure applied both forwardly and outwardly from a relatively forwardly moving, forwardly and inwardly sloping, rigid surface and all points along the entire interior perimeter of any given transverse cross section that is being expanded are pressed outward simultaneously.
  • EXAMPLE A hollow cylindrical mold with a cylindrical core positioned axially in the mold was filled with commercially pure carbonyl nickel powder having a Fisher subsieve size of about 5 microns. No binder material was used with the powder.
  • the core was 1.400 inches in diameter and the inside diameter of the mold was 2.625 inches.
  • the forward end of a frustoconical mandrel was fixed to the rearward end of the core, the cross section of the forward end of the mandrel being mated with and the same size as the rear end of the core.
  • the mandrel had a forward linear taper of about 0.171 inch per foot and was of circular cross section with a maximum diameter of 1.742 inch.
  • a sizing bar of uniform circular cross section and about iinches long was incorporated as an integral part of the mandrel, the cross section of the sizing bar being the same as the cross section of the larger (rear) end of the mandrel.
  • the end of the mold was closed with a flexible seal and a retainer clamp.
  • the core, the tapered mandrel and the sizing bar were then pulled forwardly in the mold to thus compact powder in the mold and provide a metal powder compact having dimensions of about 1.74 inch inside diameter, about 2.62 inch outside diameter and at least about 70 inches length.
  • the thus produced green compact had a highly satisfactory uniform density of about 60 percent.
  • the green compact was presintered in the mold for about 1 hour at 1,400 F.
  • the compact was then removed from the mold and given a final sintering treatment for about 8 hours at about 2,200 F. in an 88 percent nitrogen 12 percent hydrogen atmosphere. After final sintering the compact had a density of better than 90 percent of the theoretical density of pure nickel and was satisfactory for cold drawing to form wrought nickel tubing.
  • the sintered compact of the foregoing example was characterized by uniform sintered strength, which confinns that uniform green compaction was obtained when the powder was compacted with the mandrel.
  • the present invention is particularly applicable in the production of green powder metallurgical compacts which are useful for producing tubing by sintering and drawing the compacts, e.g., the invention is applicable in production of nickel tubing for transmitting corrosive fluids.
  • the invention is also applicable for production of powder compacts that are useful in the pressed and sintered condition, e.g., articles such as porous bearings, and is highly satisfactory for making self-supporting green compacts without need for having a binder in the powder.
  • a process for compacting a mass of metallic powder comprising filling a tubular cavity with a metallic powder mass to provide an inner tubular surface and an exterior tubular surface, closing the ends of said tubular cavity to closely confine the powder mass within the cavity, continuously progressively expanding the cross-sectional areas enclosed by said inner surface from one end of said cavity to the other end of said cavity with pressure applied slightly forwardly and mainly outwardly from a relatively forwardly moving rigid surface while maintaining essentially constant the cross-sectional areas enclosed by said exterior tubular surface and also maintaining essentially constant the length of the powder mass in said tubular cavity.
  • a process for making a tubular-shaped powder metallurgical compact having a longitudinally uniform interior cross section comprising confining amass of metallic powder in a tubular mold having a rigid inwardly facing mold wall a, core forming an interior passage through the powder mass and two rigidly supported expansible seals between the mold wall and the core, said mold wall and said seals being adapted to prevent outward and lengthwise movement 0 the powder,
  • mandrel is of circular cross section and is rotated around the axis of said circular cross section while being moved through the powder mass.
  • a process comprising sintering a tubular-shaped compact produced by the process set forth in claim 6 and thereafter mechanically working the sintered tubular compactto reduce the wall thickness thereof and form the compact into sintered and wrought tubing.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Powder Metallurgy (AREA)
  • Manufacturing Of Tubular Articles Or Embedded Moulded Articles (AREA)
US756222A 1968-08-29 1968-08-29 Production of tubular products from metallic powders Expired - Lifetime US3615382A (en)

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US75622268A 1968-08-29 1968-08-29

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US (1) US3615382A (de)
AT (1) AT302002B (de)
BE (1) BE738178A (de)
DE (1) DE1943238B2 (de)
FR (1) FR2016606A1 (de)
GB (1) GB1236846A (de)
NL (1) NL6913150A (de)
SE (1) SE357687B (de)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3773506A (en) * 1971-03-26 1973-11-20 Asea Ab Method of manufacturing a blade having a plurality of internal cooling channels
US4935198A (en) * 1986-09-03 1990-06-19 Avesta Nyby Powder Ab Method for the powder-metallurgical manufacture of tubes or like elongated profiles
US5314655A (en) * 1988-12-02 1994-05-24 Manganese Bronze Limited Method and apparatus for producing continuous powder metallurgy compacts
US5470527A (en) * 1992-04-21 1995-11-28 Kabushiki Kaisha Toshiba Ti-W sputtering target and method for manufacturing same
US6017489A (en) * 1999-02-17 2000-01-25 Federal-Mogul World Wide, Inc. Method of densifying powder metal preforms
US20050064221A1 (en) * 2001-05-14 2005-03-24 Lu Jyh-Woei J. Sintering process and tools for use in metal injection molding of large parts
CN102029387A (zh) * 2010-09-21 2011-04-27 重庆文理学院 一种条形样高温真空保护气氛烧结模具及工艺
US20120183637A1 (en) * 2009-09-15 2012-07-19 Sea Hoon Lee Mold for synthesizing ceramic powder by means of a spark plasma sintering method
US20140034571A1 (en) * 2011-03-31 2014-02-06 Japan Tobacco Inc. Filter manufacturing machine, filter manufacturing method using the machine, and hollow filter
US11446737B2 (en) * 2016-08-18 2022-09-20 Diamet Corporation Molding die and molding method
CN115138846A (zh) * 2022-09-02 2022-10-04 中国航发北京航空材料研究院 一种粉末冶金用包套双重型芯的制备方法

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4435359A (en) * 1982-06-21 1984-03-06 Huntington Alloys, Inc. Apparatus and method for fabricating tubes from powder
JP2707524B2 (ja) * 1986-06-17 1998-01-28 住友電気工業株式会社 長尺セラミックス製品の製造方法
US5252288A (en) * 1986-06-17 1993-10-12 Sumitomo Electric Industries, Inc. Method for producing an elongated sintered article
WO1995013158A1 (fr) * 1993-11-10 1995-05-18 Vladimir Georgievich Smelikov Procede de production d'articles a partir de metaux et d'alliages
CN115383111B (zh) * 2022-08-26 2023-12-19 山东滨州华创金属有限公司 多组元含能合金材料制备工艺及多组元含能合金材料

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3773506A (en) * 1971-03-26 1973-11-20 Asea Ab Method of manufacturing a blade having a plurality of internal cooling channels
US4935198A (en) * 1986-09-03 1990-06-19 Avesta Nyby Powder Ab Method for the powder-metallurgical manufacture of tubes or like elongated profiles
US5314655A (en) * 1988-12-02 1994-05-24 Manganese Bronze Limited Method and apparatus for producing continuous powder metallurgy compacts
US5470527A (en) * 1992-04-21 1995-11-28 Kabushiki Kaisha Toshiba Ti-W sputtering target and method for manufacturing same
US6017489A (en) * 1999-02-17 2000-01-25 Federal-Mogul World Wide, Inc. Method of densifying powder metal preforms
US7635405B2 (en) * 2001-05-14 2009-12-22 Honeywell International Inc. Sintering process and tools for use in metal injection molding of large parts
US20050064221A1 (en) * 2001-05-14 2005-03-24 Lu Jyh-Woei J. Sintering process and tools for use in metal injection molding of large parts
US20120183637A1 (en) * 2009-09-15 2012-07-19 Sea Hoon Lee Mold for synthesizing ceramic powder by means of a spark plasma sintering method
US9096474B2 (en) * 2009-09-15 2015-08-04 Korea Institute Of Machinery & Materials Mold for synthesizing ceramic powder by means of a spark plasma sintering method
CN102029387A (zh) * 2010-09-21 2011-04-27 重庆文理学院 一种条形样高温真空保护气氛烧结模具及工艺
US20140034571A1 (en) * 2011-03-31 2014-02-06 Japan Tobacco Inc. Filter manufacturing machine, filter manufacturing method using the machine, and hollow filter
US9427929B2 (en) * 2011-03-31 2016-08-30 Japan Tobacco Inc. Filter manufacturing machine, filter manufacturing method using the machine, and hollow filter
US11446737B2 (en) * 2016-08-18 2022-09-20 Diamet Corporation Molding die and molding method
CN115138846A (zh) * 2022-09-02 2022-10-04 中国航发北京航空材料研究院 一种粉末冶金用包套双重型芯的制备方法

Also Published As

Publication number Publication date
NL6913150A (de) 1970-03-03
SE357687B (de) 1973-07-09
DE1943238B2 (de) 1974-03-21
AT302002B (de) 1972-09-25
BE738178A (de) 1970-03-02
DE1943238A1 (de) 1970-03-05
FR2016606A1 (de) 1970-05-08
GB1236846A (en) 1971-06-23

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