US3361864A - Furnace for treatment of wax-bonded sinterable preforms - Google Patents

Furnace for treatment of wax-bonded sinterable preforms Download PDF

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Publication number
US3361864A
US3361864A US423509A US42350965A US3361864A US 3361864 A US3361864 A US 3361864A US 423509 A US423509 A US 423509A US 42350965 A US42350965 A US 42350965A US 3361864 A US3361864 A US 3361864A
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United States
Prior art keywords
furnace
container
housing
wax
preforms
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 - Lifetime
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US423509A
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English (en)
Inventor
Vollmer Helmut
Huchler Kurt
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Bendix Corp
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Bendix Corp
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Filing date
Publication date
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Publication of US3361864A publication Critical patent/US3361864A/en
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J6/00—Heat treatments such as Calcining; Fusing ; Pyrolysis
    • B01J6/001—Calcining
    • 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
    • B22F3/1017—Multiple heating or additional steps
    • B22F3/1021—Removal of binder or filler
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B5/00—Muffle furnaces; Retort furnaces; Other furnaces in which the charge is held completely isolated
    • F27B5/04—Muffle furnaces; Retort furnaces; Other furnaces in which the charge is held completely isolated adapted for treating the charge in vacuum or special atmosphere

Definitions

  • the first passage leads from within the container to the space between container and housing.
  • a second passage leads from the space between container and housing externally to associated condensing and pumping mechanism.
  • Externally-controllable valve means are operative to selectively interconnect the first and second passages. The arrangement permits, without handling of the wax-bonded sinterable preforms, first the wax removal and condensing in the associated mechanism, and secondly, vacuum sintering of the preforms.
  • the binding material In the sintering technique it is useful to press the powdered raw material with the use of a binding material into preforms, which then are treated in a furnace at correspondingly higher temperatures to become the end prod uct.
  • Various materials are used as the binding means among which are waxlike substances. Before or during the real sintering process the binding material must be removed.
  • One of the known processes in the case of use of wax as the binding material involves the following: after the pressing of the preforms to attain a sufficiently permanent shape, they are heated to a temperature sufficient to vaporize the wax so that the wax vapor can be pumped off or trapped with cooled condensers.
  • the use of special vacuum dewaxing furnaces with their auxiliary equipment is costly, time consuming and unsatisfactory.
  • the furnace according to the invention for the treatment of wax-bonded preforms to be sintered consists of a closed furnace housing with an evacuation connection, a container situated within it and heating means for the exposure and heating of the preforms to be dewaxed and sintered and is characterized in that the aforementioned container on the inside of the evacuable furnace housing is built with an evacuation opening which is connected to a wax vapor condenser by a second separate evacuation pipe.
  • One example of the carrying out of the invention is represented in the accompanied schematic drawing in which:
  • FIGURE 1 is a schematic view of a furnace embodying the present invention.
  • FIGURE 2 is a fragmentary view similar to FIGURE 1 but showing another embodiment of the present invention.
  • numeral 1 designates a closed furnace housing which can be evacuated by means of a high-vacuum pump (not shown) through the evacuation connection 2.
  • a heating arrangement for the container 4 such as an induction heating coil 5 surrounding the container 3.
  • Container 4 is located within container 3 and may be either metal or graphite depending on temperature requirements.
  • Container 3 is made of quartz or quartz-like material.
  • the container 4, as shown in the drawing, consists of a graphite cup 6 with a removable cover 7 embedded in carbon grit 8 which surrounds the sinter material on all sides. The carbon grit 8 above the cover 7 may be loosely packed to facilitate removal of the carbon grit 8 and allow insertion and removal of the sinter material.
  • the container 4 has an opening 11 in the bottom which is connected to a second evacuation connection 12.
  • Conduit 13 extends from connection 12 through the wall of the furnace housing in a vacuum tight manner to the wax condenser 18 which is adapted to be heated by well known means (not shown).
  • a shaft 15 is disposed within conduit 13 and is connected to a small plate valve 16 to open and close said valve and thereby respectively connect conduit 12 and the interior of container 4 to the space 9 of the evacuable furnace housing 1 or to conduit -13 as desired.
  • the shaft 15 is likewise carried out from the furnace housing in a vacuum tight manner and is provided with a hand-wheel 1'7.
  • the valve plate 16 and the hand wheel 17 are shown in the closed position of the valve in FIGURE 1.
  • the open position is shown by dotted lines.
  • the condenser '18 is of a well known construction and consists, in the example given, of a vessel 20, in which are arranged coolable baffie plates 21 for the condensation of the wax vapor.
  • the centrally arranged carrier 22 for the baffle plates is hollow and suitable cooling fluid can be circulated through it.
  • the described furnace is suitable for dewaxing as well as sintering.
  • the sinter material is introduced into the container 4 which is then closed.
  • the container and the furnace housing 1 are evacuated through the open valve 16 and the pump connected at 2.
  • the valve 16 is then closed and the sinter material brought to the dewaxing temperature by energizing the heater.
  • the evolving wax vapor is removed through the pipe 13 and condensed in condenser 18.
  • the non-condensable gases, which emerge at the same time from the container 4, as was previously mentioned, are removed by the pump 19.
  • the induction coil 5 may be connected to an electrical A-C current 3 source, not shown, through vacuum tight connectors, out of the plane of the drawing and therefore not shown, which are known to those skilled in the art.
  • auxiliary gas can, for example, be argon, nitrogen or hydrogen and may be admitted through the evacuated connection 2. Overpressure during the dewaxing process hinders the possible escape of the wax vapor into space 9 through the lack of thightness of the sinter material container 4.
  • An auxiliary gas atmosphere in the furnace may also be used in the sintering process itself to reduce the vaporization of components of the sinter material at the higher temperature used.
  • valve 25 After the carrying out of the dewaxing it is not necessary to remove the material from the container. In most cases the condenser can be simply shut off from the furnace by means of valve 25. The valve 16 is opened and the space 9 is well as the sinter material container .are brought to high vacuum and after increasing the heat the sintering is carried out in the usual manner.
  • the necessary reduced pressure adjusts itself after a short time to the sintering process and lies somewhere between 10 to torr.
  • the operating technique is especially advantageous if two or more of the sintering furnaces according to the present invention can be combined into a single operating unit.
  • the charge of one furnace may be dewaxed white the other is being sintered.
  • the pipe 23 in FIGURE 1 may be removable from the furnace.
  • FIGURE 2 A further possibility for such manifold arrangement is shown in FIGURE 2.
  • the same parts are designated by the same reference numbers as in FIGURE 1.
  • the connection between pipe 12 from the bottom of the sinter material container 4 and the condenser 18 is different from that in FIGURE 1.
  • connection comprises a flexible rubber tube 32 and with its connection piece 30 is detachably connected to pipe 12 through a shut-off valve 31 secured to the furnace housing 1.
  • Tube 32 is retractable from the evacuated furnace to the position (30732) as shown by the dotted lines in FIGURE 2.
  • Tube 32 may be heated in practice by suitable well known means (not shown).
  • the shut-off valve 31 is of known construction and will therefore not be further described.
  • An 0 ring gasket seal 33 prevents the entrance of atmospheric air into the furnace while the valve 31 is opened for the insertion or removal of the evacuation tube. After drawing back the pipe or tube 32 from the furnace the valve 31 can be again closed and the tube detached from the furnace. The condenser with its attached pumps is then ready for use in dewaxing of sinter material in other furnaces of the same type.
  • Wax in the sense of the present invention will be understood to mean every principle binding material of the higher hydrocarbons, which can find use in the sintering technique, especially in the production of hard metal preforms.
  • a furnace for the treatment of wax-bonded sinterable preforms comprising: a housing; an enclosed container adapted to hold sinterable preformsin the interior thereof and in said housing, defining a space adapted to be evacuated intermediate said housing and said container; induction means for heating said container; a first evacuation connection opening on one end into the interior of said container and on another end into said space intermediate housing and container; a second evacuation connection opening into said space on one end and extending exterior of said housing; valve means controllable externally of said housing for selectively interconnecting said first and second evacuation connections, condenser means exterior of said housing means and conduit means interconnecting said second evacuation connection and said condenser means.
  • conduit means is detachably connected to said second evacuation connection and a shut-off valve is connected to said second evacuation connection to close said connection when said conduit means is detached.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Manufacturing & Machinery (AREA)
  • General Engineering & Computer Science (AREA)
  • Powder Metallurgy (AREA)
  • Crucibles And Fluidized-Bed Furnaces (AREA)
US423509A 1964-01-09 1965-01-05 Furnace for treatment of wax-bonded sinterable preforms Expired - Lifetime US3361864A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH23764A CH406792A (de) 1964-01-09 1964-01-09 Ofen zur Behandlung von zu sinternden, wachsgebundenen Formkörpern

Publications (1)

Publication Number Publication Date
US3361864A true US3361864A (en) 1968-01-02

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ID=4182404

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US423509A Expired - Lifetime US3361864A (en) 1964-01-09 1965-01-05 Furnace for treatment of wax-bonded sinterable preforms

Country Status (7)

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US (1) US3361864A (it)
BE (1) BE656841A (it)
CH (1) CH406792A (it)
DE (1) DE1265346B (it)
FR (1) FR1419364A (it)
GB (1) GB1018049A (it)
NL (1) NL6413038A (it)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3654374A (en) * 1969-07-25 1972-04-04 Adamas Carbide Corp Apparatus for and method of de-waxing, presintering and sintering powdered metal compacts
US3871630A (en) * 1972-05-05 1975-03-18 Leybold Heraeus Verwaltung Apparatus for sintering pressed powder elements containing hydrocarbons
US4321446A (en) * 1979-08-21 1982-03-23 Toho Beslon Co., Ltd. Apparatus for production of graphite fibers
US4931610A (en) * 1989-06-08 1990-06-05 Hughes William L Induction heated rotary kiln
US5272298A (en) * 1991-04-03 1993-12-21 Mitsubishi Jukogyo Kabushiki Kaisha Apparatus for vacuum deposition of sublimative substance

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2055946A5 (it) * 1969-08-08 1971-05-14 Commissariat Energie Atomique
FR2542650B1 (fr) * 1983-03-14 1985-10-25 Commissariat Energie Atomique Procede de fabrication de pieces en materiau inorganique presentant une forte porosite et pour la mise en oeuvre de ce procede
JPS63311082A (ja) * 1987-06-12 1988-12-19 日本鋼管株式会社 高密度焼結体の製造装置

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2789153A (en) * 1956-02-28 1957-04-16 Mark Albert Furnace for producing single crystals for transistors

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2789153A (en) * 1956-02-28 1957-04-16 Mark Albert Furnace for producing single crystals for transistors

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3654374A (en) * 1969-07-25 1972-04-04 Adamas Carbide Corp Apparatus for and method of de-waxing, presintering and sintering powdered metal compacts
US3871630A (en) * 1972-05-05 1975-03-18 Leybold Heraeus Verwaltung Apparatus for sintering pressed powder elements containing hydrocarbons
US4321446A (en) * 1979-08-21 1982-03-23 Toho Beslon Co., Ltd. Apparatus for production of graphite fibers
US4931610A (en) * 1989-06-08 1990-06-05 Hughes William L Induction heated rotary kiln
US5272298A (en) * 1991-04-03 1993-12-21 Mitsubishi Jukogyo Kabushiki Kaisha Apparatus for vacuum deposition of sublimative substance

Also Published As

Publication number Publication date
DE1265346B (de) 1968-04-04
NL6413038A (it) 1965-07-12
FR1419364A (fr) 1965-11-26
GB1018049A (en) 1966-01-26
BE656841A (it) 1965-04-01
CH406792A (de) 1966-01-31

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