EP0103056B1 - Metallischer Sinterkörper und Verfahren zu seiner Herstellung - Google Patents

Metallischer Sinterkörper und Verfahren zu seiner Herstellung Download PDF

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Publication number
EP0103056B1
EP0103056B1 EP82304852A EP82304852A EP0103056B1 EP 0103056 B1 EP0103056 B1 EP 0103056B1 EP 82304852 A EP82304852 A EP 82304852A EP 82304852 A EP82304852 A EP 82304852A EP 0103056 B1 EP0103056 B1 EP 0103056B1
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EP
European Patent Office
Prior art keywords
seat
annular
polymeric material
matrix
metal matrix
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
EP82304852A
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English (en)
French (fr)
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EP0103056A1 (de
Inventor
Ricardo Gonzalez
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.)
Worcester Controls Corp
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Worcester Controls Corp
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Filing date
Publication date
Application filed by Worcester Controls Corp filed Critical Worcester Controls Corp
Priority to EP82304852A priority Critical patent/EP0103056B1/de
Priority to DE8282304852T priority patent/DE3273359D1/de
Priority to AT82304852T priority patent/ATE22242T1/de
Publication of EP0103056A1 publication Critical patent/EP0103056A1/de
Application granted granted Critical
Publication of EP0103056B1 publication Critical patent/EP0103056B1/de
Expired legal-status Critical Current

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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
    • B22F3/24—After-treatment of workpieces or articles
    • B22F3/26—Impregnating
    • 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
    • B22F3/24—After-treatment of workpieces or articles

Definitions

  • This invention relates to sintered metal bodies, and in particular but not exclusively, to such bodies of annular configuration suitable for use as the seat of a plug valve of the ball valve kind. It is desirable to use metal seats in such ball valves under certain conditions since the resultant valve structure can resist higher temperatures and pressures than valves which use other types of seat materials such as plastics materials, for example polytetrafluoroethylene (PTFE).
  • PTFE polytetrafluoroethylene
  • the McFarland patent discloses a metal seat for use in a floating type ball valve, the seat being formed of sintered metal of which the exterior surfaces are coated with a layer of cured polymeric material which extends to some extent into the interior pores or interstices of the sintered metal body.
  • valve seat of the McFarland patent is a porous structure which relies upon a continuous surface coating of polymeric material to provide the desired seal, or upon a caulking action of the polymeric material within the seat to effect a desired seal in the event that the polymer coating is destroyed by any means such as fire or abrasion.
  • valve seat of the McFarland patent being essentially porous throughout, tends to leak fluid through the seat when the seat is subjected to pressure if the integrity of the surface coating is impaired and the above-mentioned caulking effect is imperfect.
  • An object of the present invention is to provide a method of fabricating a leak-proof seat for use in a ball valve, together with a non-porous leak-free valve seat or seal for use in a ball valve offering improvements in relation to one or more of the shortcomings of the prior art as identified above.
  • the foregoing disadvantages of the structure disclosed in the McFarland patent are largely mitigated by providing a seat for a floating ball valve consisting of a sintered metal matrix of which the interparticulate spaces are completely filled with cured polymeric material, whereby the seat structure, in addition to being of metal construction and therefore adapted for use in those applications where metal seats are desirable, is nonporous throughout without regard to the presence or absence of a surface coating of polymeric material.
  • a surface coating can be provided to achieve additional initial lubricity
  • the provision of such a surface coating is optional only since the cured polymeric material which fills the interstices of the sintered metal matrix and in particular the portion thereof which is adjacent the surface of the seat, provides the desired lubricity. Any increase in temperature of the seat with a resultant expansion of the polymeric material within the seat, causes an extrusion or migration of said polymeric material from the interior of the seat through the surface of the seat to provide additional lubricity.
  • the expanded interior polymeric material is obliged to migrate through the matrix of sintered material towards the exterior surface of the seat and to exude from the matrix onto the seat surface thereby increasing the lubricity of the seat at the seat/ball interface of the valve.
  • a sintered metal body such as a valve member or valve seat according to the present invention can be prepared by a series of steps, and by using metal and polymeric materials in accordance with the disclosure of the above-mentioned United States patent to McFarland.
  • a sintered metal "green compact" structure is initially fabricated in the form and shape conventionally employed for ball valve seats and members, and then the green compact is sintered to fuse adjacent metal particles to each other. Then the resultant valve member or seat is impregnated with an emulsion of uncured polymeric material having lubricity, the impregnation being effected by means of a vacuum and/or positive pressure step. The liquid vehicle employed in the emulsion is then dried, and then the residual polymeric material is cured by heating.
  • a valve seat prepared by a series of steps as described above is considered to be completely fabricated except for a final surface finishing step such as grinding, to provide the seat with a desired surface accuracy, and the final seat is porous throughout except for a layer of polymeric material which covers the exterior surfaces of the seat.
  • the product of the above steps constitutes only the starting point for a further portion of the manufacturing process and, following the above-mentioned curing step, the valve seat or member is placed in a die and subjected to extremely high pressures which operate to collapse substantially all of the interparticulate cavities and voids throughout the seat onto the portions of the cured polymeric material within the sintered metal matrix.
  • the cured polymeric material within the sintered metal seat or member completely fills all of the collapsed interparticulate spaces within the seat and the seat is rendered nonporous throughout.
  • the seat can then be surface-finished, if necessary, or the seat can optionally be coated with a further layer of polymeric material which is thereafter surface-finished if necessary.
  • the sintered metal elements are proposed to be associated with a lubricant or polymeric material, see for example the United States patents: in addition to the above-discussed US patent 3,592,440 (McFarland).
  • prior workers in the field have proposed the use of a "coining" or compression of a sintered metal body-see for example the above-mentioned Chmura and Harris patents, but these proposals have been such that the resultant structure exhibits a high density or nonporous portion adjacent the surface of the body only, and a lower density porous structure underlies the surface of the body.
  • the pressure-applying step of the present invention is such that the valve seat or body so produced exhibits substantially uniform density throughout and is nonporous throughout.
  • a quantity of powdered metal e.g. stainless steel or bronze
  • a die whose interior configuration corresponds to the configuration desired of the final structure (e.g., an annular configuration when the object being prepared is a seat for use in a ball valve)
  • the powdered metal is subjected to pressures of the order of 30 tons per square inch to form a unitary metal body having the desired configuration.
  • the individual metal particles are held together simply by interparticle friction and the structure is termed a "green compact" in the parlance of the trade.
  • the green compact is then placed in a furnace and subjected to a high temperature which is less than the melting point of the metal material in the seat but which is sufficiently high to cause a coalescing of the interfaces between the various particles in the green compact to unify the structure into a sintered metal matrix.
  • the resultant structure is porous.
  • a PTFE emulsion is formed by mixing a quantity of submicron PTFE particles in an appropriate vehicle such as water, along with some wetting agents; it must be understood, however, as discussed in the afore-mentioned US patent 3,592,440 (McFarland), that other uncured polymeric materials can be employed and entrained or suspended in other liquid vehicles.
  • the emulsion produced in step 12, and the sintered metal seat produced by step 11 are then, in a step 13, placed in a vacuum chamber, initially in spaced relation to one another, and a vacuum is applied to the chamber to remove all air from the voids or pores in the sintered metal seat.
  • the sintered metal seat is then immersed in the emulsion, and the vacuum is broken (if desired, a positive pressure may also be introduced into the chamber) to drive the emulsion into the pores of the sintered metal seat.
  • the resultant polymer impregnated seat is then removed from the chamber and permitted to dry, in a step 14, e.g., at a temperature which is below the boiling point of water or which is otherwise suitable to remove the water or other liquid vehicle constituents from the emulsion, leaving a residue of PTFE (and/or of whatever other polymer is employed) in the pores of the sintered metal seat.
  • the impregnated seat is again placed in a furnace in a step 15, and is heated to sinter and cure the PTFE at an appropriate "Teflon-sintering" temperature, i.e. one which is considerably lower than the sintering temperature previously employed for the metal seat alone.
  • step 10 By way of example, if the green compact prepared in step 10 constitutes stainless steel particles, it would be sintered at approximately 1371°C (2500°F) whereas Teflon is sintered (in step 15) at around 371°C (700°F). Sintering step 15 is needed to coalesce the Teflon particles, previously in the emulsion, with one another since, otherwise, the Teflon particles would be driven out of the pores in the sintered metal seat when the seat is later subjected to fluid pressure.
  • Step 16 the structure is then subjected, in a step 16, to extremely high pressures which collapse substantially all of the interparticulate cavities and voids throughout the seat onto the enclosed PTFE or other cured polymer within the seat, to eliminate all interparticulate voids in the sintered metal seat to the extent possible, and to render the complete seat impervious to fluid flow, i.e., to make the final product "leak free” throughout.
  • Step 16 can be effected in the manner shown in Fig.
  • annular, polymer impregnated, sintered metal seat 20, produced by method steps 10­15 described above, is placed in a die 21 which has a cooperating plunger 22 that, together, define exterior surfaces which closely conform to all of the exterior surfaces of seat 20, whereafter extremely high pressures, in the order of 40 tons per square inch (6.3 tonnes per square centimetre), are applied to the seat to collapse all voids within the seat material and to render it nonporous and of substantially uniform density throughout.
  • the seat 20 following completion of step 16, is of sintered metal construction wherein cured PTFE (or whatever other polymer having desired lubricity is employed) fills the interparticulate spaces or collapsed voids of the sintered metal matrix throughout the body of the seat.
  • the seat is, accordingly, nonporous throughout. Indeed, seats constructed in accordance with the present invention have been found to hold bubble tight on helium, which is a most stringent leakage test. Those incremental portions of the polymer material which are adjacent the surface of the seat act as a lubricant at said surface.
  • step 16 since all interparticulate voids have been collapsed by step 16, when the seat is used in an application where the temperature is higher than room temperature, the cured polymer within the seat expands but has no place to go; and the resultant expansion is therefore manifested as an increase in the internal pressure of the seat through the matrix of sintered metal material, which experiences a migration of the cured polymer toward the surface of the seat and causes some extrusion of the polymer from the seat surface to increase the lubricity of the seat at the seat/ball interface.
  • the seat may, in a step 17, be dipped in a PTFE emulsion which is much more viscous in consistency than the emulsion in steps 12 and 13, to coat the seat with a layer of Teflon® or other polymer having desired lubricity, whereafter the coating layer is again sintered and cured to provide the seat with an outer envelope which gives the seat additional initial lubricity.
  • this final step is optional.
  • the outer polymer layer if provided, may be characteristically coloured to clearly identify the type of seat which has been produced.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Powder Metallurgy (AREA)
  • Adornments (AREA)

Claims (7)

1. Verfahren zur Herstellung eines lecksicheren Sitzes zur Verwendung in einem Kugelventil, umfassend die Stufen des Pressens einer Masse von Metallteilchen, wobei die Masse eine ringförmige Form besitzt und eine ringförmige Fläche aufweist, die geeignet ist, in Nähe einer drehbaren Kugel in einem Kugelventil angeordnet zu werden, des Sinterns der ringförmigen Masse, um benachbarte Metallteilen aneinander zu schmelzen und diese Teilchen dabei in eine poröse Metallmatrix mit ringförmiger Form zusammenfließen zu lassen, des Imprägnierens der ringförmigen Metallmatrix mit einer Emulsion, bestehend aus nicht gehärteten Teilchen eines Polymerwerkstoffes, der von einem flüssigen Mittel getragen ist, wobei der Imprägnierschritt unter Überdruckbedingungen ausgeführt wird, um die Emulsion in zwischen den Teilchen liegenden Räume der Metallmatrix hineinzudrücken und um diese zwischen den Teilchen liegenden Räume in der gesamten, ringförmigen Metallmatrix vollständig mit dieser Emulsion zu füllen, des Trocknens der mit der Emulsion imprägnierten, ringförmigen Metallmatrix, um das flüssige Mittel von dieser zu entfernen, wobei ein Rückstand aus nicht gehärteten Polymerteilchen in den zwischen den Teilchen liegenden Räumen zurückgelassen wird, und des nachfolgenden Erhitzens der ringförmigen Metallmatrix, um die Polymerteilchen, die in den zwischen den Teilchen liegenden Räumen zurückgeblieben sind, zu sintern und zu härten, gekennzeichnet durch die Stufe des Einsetzens dieser Metallmatrix in eine Form, die einen ringförmigen Hohlraum aufweist, dessen Innenform der Außenringform der mit gehärtetem Polymer imprägnierten, ringförmigen Metallmatrix eng entspricht und dann des Anlegens von Druck auf die Außenflächen der ringförmigen Metallmatrix unter Verwendung der Form in einer Größe in der Größenordnung von 30 bis 40 t je Quadratinch (463 bis 618 MPa), um das Innere der Matrix auf das gehärte Polymer in dieser Matrix zusammenzudrücken, um so alle Hohlräume im gesamten Inneren der ringförmigen Metallmatrix zu beseitigen, die nach den Stufen des Trocknens und Sinterns/Härtens verbleiben, um so die ringförmige Matrix durchgehend porenfrei zu machen, wobei die Stufe des Druckanlegens so ausgeführt wird, um einen ringförmigen Körper herzustellen, dessen Form und Abmessungen für die Verwending als Kugelsitz in einem Drehkugelventil geeignet sind, wobei der ringförmige Körper nach Beendigung der Stufe des Druckanlegens in seinem gesamten Inneren des Körpers und an den Außenflächen des Körpers eine im wesentlichen einheitliche Dichte hat.
2. Verfahren nach Anspruch 1, gekennzeichnet durch die weiteren Schritte, die nach der Druckanlegungsstufe ausgeführt werden, des Beschichtens der Außenflächen des ringförmigen Körpers mit einer weiteren Emulsion von Polymerteilchen, wobei die weitere Emulsion viskoser ist als die in der Imprägnierstufe verwendete Emulsion und des nachfolgenden Trocknens dieser Beschichtung und Sinterns und Härtens der Polymerteilchen in der Beschichtung, um den ringförmigen Körper in eine äußere Hülle aus Polymerwerkstoff einzuschließen.
3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß der Polymerwerkstoff Polytetrafluoräthylen umfaßt.
4. Porenfreier, leckfreier Ventilsitz oder Dichtung, umfassen einer ringförmigen Körper aus gesintertem, teilchenförmigen Metall, das eine Metallmatrix bildet, die eine Außenform besitzt, die für die Verwendung als Sitz in einem Kugelventil, der eine drehbare Kugel in einem solchen Ventil aufnimmt, geeignet ist und einem gehärteten Polymerwerkstoff mit Schmierfähigkeit, der in der Metallmatrix abgelegt ist, dadurch gekennzeichnet, daß alle zwischen den Teilchen liegenden Räume der Metallmatrix, umfassend das Innere des ringförmigen Körpers vollständig mit einem gehärten, polymeren Werkstoff, der Schmierfähigkeit besitzt, gefüllt sind, wobei der polymere Werkstoff die Metallmatrix über das gesamte Innere des Körpers porenfrei macht und wobei Temperaturerhöhungen des Körpers, die zu einer Ausdehnung des Polymerwerkstoffes in der Matrix führen, ein Austreiben von Teilen des gehärteten Polymerwerkstoffes vom Inneren des Körpers zu den Außenflächen des Körpers bewirken, die geeignet sind, die drehbare Kugel eines Kugelventils aufzunehmen, um so die Außenflächen zu schmieren, während die zwischen den Teilchen liegenden Räume im Inneren des Körpers vollständig mit den nicht extrudierten Anteilen des gehärteten Polymerwerkstoffes gefüllt bleiben und wobei die Außenflächenteile des Körpers im wesentlichen die gleiche Dichte besitzen, wie das Innere des Körpers.
5. Ventilsitz oder Dichtung nach Anspruch 4, dadurch gekennzeichnet, daß der Polymerwerkstoff Polytetrafluoräthylen umfaßt.
6. Ventilsatz oder Dichtung nach Anspruch 4 oder Anspruch 5, dadurch gekennzeichnet, daß das Äußere des Sitzes oder der Dichtung vollständig durch eine Lage des gehärteten Polymerwerkstoffes bedeckt ist.
7. Ventilsitz oder Dichtung, hergestellt nach dem Verfahren gemäß einem der Ansprüche 1 bis 3.
EP82304852A 1982-09-14 1982-09-14 Metallischer Sinterkörper und Verfahren zu seiner Herstellung Expired EP0103056B1 (de)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP82304852A EP0103056B1 (de) 1982-09-14 1982-09-14 Metallischer Sinterkörper und Verfahren zu seiner Herstellung
DE8282304852T DE3273359D1 (en) 1982-09-14 1982-09-14 Sintered metal body and method of making same
AT82304852T ATE22242T1 (de) 1982-09-14 1982-09-14 Metallischer sinterkoerper und verfahren zu seiner herstellung.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP82304852A EP0103056B1 (de) 1982-09-14 1982-09-14 Metallischer Sinterkörper und Verfahren zu seiner Herstellung

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EP0103056A1 EP0103056A1 (de) 1984-03-21
EP0103056B1 true EP0103056B1 (de) 1986-09-17

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AT (1) ATE22242T1 (de)
DE (1) DE3273359D1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109676141A (zh) * 2017-12-06 2019-04-26 全亿大科技（佛山）有限公司 异形复杂金属制品的制造方法及异形复杂金属制品

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2188744C2 (ru) * 2000-01-19 2002-09-10 Открытое акционерное общество "АВТОВАЗ" Способ изготовления седел клапанов для двс из порошкового материала

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB674056A (en) * 1948-11-16 1952-06-18 Edras Soc Manufacture of self-lubricating metallic bodies by sintering metallic powders
US2838829A (en) * 1956-09-05 1958-06-17 Toefco Engineering Company Method of making bearings
US3592440A (en) * 1969-10-16 1971-07-13 Hills Mccanna Co Ball valve

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109676141A (zh) * 2017-12-06 2019-04-26 全亿大科技（佛山）有限公司 异形复杂金属制品的制造方法及异形复杂金属制品

Also Published As

Publication number Publication date
DE3273359D1 (en) 1986-10-23
EP0103056A1 (de) 1984-03-21
ATE22242T1 (de) 1986-10-15

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