US3641250A - Vacuum furnace - Google Patents

Vacuum furnace Download PDF

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Publication number
US3641250A
US3641250A US38721A US3641250DA US3641250A US 3641250 A US3641250 A US 3641250A US 38721 A US38721 A US 38721A US 3641250D A US3641250D A US 3641250DA US 3641250 A US3641250 A US 3641250A
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United States
Prior art keywords
chamber
furnace
sealing plate
piston
opening
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
Application number
US38721A
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English (en)
Inventor
Karl Hintenberger
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Individual
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Individual
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Publication date
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Publication of US3641250A publication Critical patent/US3641250A/en
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Classifications

    • 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
    • F27B17/00—Furnaces of a kind not covered by any preceding group
    • F27B17/02—Furnaces of a kind not covered by any preceding group specially designed for laboratory use

Definitions

  • a heating element in the top portion of the furnace chamber bounds a firing zone much hotter than the lower portion of the chamber so that a green body freshly introduced into the chamber may be protected from the highest furnace temperature while the furnace is being evacuated, and moved into the firing zone after the furnace is fully evacuated.
  • the moving mechanism is pneumatically operated.
  • This invention relates to vacuum fumaces, and particularly to a furnace suitable for firing dental porcelain.
  • this invention is concerned with an improvement in an electrically heated furnace whose chamber is downwardly open and can be sealed by a plate connected to the work carrier as disclosed in my German Pat. No. 1,160,777 or my U.S. Pat. No. 3,128,326.
  • a green body of ceramic material may be moved for preheating into the bottom portion of the furnace chamber on the carrier, and thereafter moved into the firing zone at the top of the chamber, the chamber opening being sealed simultaneously.
  • the furnace of the invention has a shell whose chamber may be connected with the ambient atmosphere by an opening.
  • a heating device in the chamber defines a firing zone whose temperature is higher than that of the remainder of the chamber when the heating device operates.
  • a support is mounted for movement outside the chamber toward and away from an operating position adjacent the opening.
  • a sealing device responds to movement of the support into the operating position for sealing the chamber opening, whereupon air may be withdrawn from the chamber for evacuating the same.
  • a transfer mechanism is interposed between the support and a work carrier for the object to be fired and moves the carrier into the chamber when the support moves toward the operative position. The carrier may be transferred in the chamber between the firing zone and the cooler remainder of the chamber by the transfer mechanism while the support is in its operating position.
  • FIG. 1 shows a known dental vacuum furnace arrangement in front elevation, and partly in section
  • FIG. 2 shows a portion of the furnace arrangement of FIG. 1 incorporating the features of the invention in rear elevational section on a much larger scale.
  • FIG. I there is seen a generally cubical steel shell 4 which is lined with fire bricks 3.
  • the bricks enclose the furnace chamber 1 whose bottom is open and which communicates with the ambient atmosphere through a circular opening 8 in the bottom wall 17 of the shell 4 in the illustrated condition of the apparatus.
  • An annular heating element 2 bounds the topmost portion of the chamber 1, as is described in more detail in my simultaneously filed application Ser. No. 38,720, for a FUR- NACE CHAMBER.
  • a vacuum line 7 leads into the chamber through the top of the shell 4 and a bore in a brick 3.
  • Four steel columns 5 spacedly attach the shell 4 to a base 6 which carries the furnace controls and indicating instruments, conventional in themselves, and not directly relevant to this invention.
  • the base 6 also carries the operating mechanism 9 for moving workpieces into and out of the chamber 1 and for sealing the charged chamber with which this invention is more specifically concerned.
  • a ceramic carrier 15 is releasably mounted atop the mechanism 9, and carries a ceramic tooth 14 which is ready to be fired.
  • the mechanism 9 according to the invention is shown in detail in FIG. 2.
  • An upright cylinder 11 is fixedly mounted in the base 6 in axial alignment with the opening 8. Its top is open, and its bottom is connected to a supply line 12 for compressed air.
  • a hollow plunger or piston 10 is axially slidable in the cavity of the cylinder 11 in telescoping engagement. The interior of the plunger 10 communicates with the cylinder cavity through a throttling orifice 18 in the bottom wall 25 of the plunger.
  • the top end of the plunger 10 projects from the cylinder 11 in the illustrated lowermost position of the plunger and carries a circular radial plane or sealing plate 10'.
  • a flat ring 16 of asbestos composition is coaxially set into the top face of the sealing plate 10' for engagement with the bottom wall 17 about the opening 8 when the plunger 10 moves outward of the cylinder 11.
  • the bore of the plunger 10 is upwardly open and receives a telescoping transfer mechanism mainly consisting of a cylindrical driver 13 of solid metal axially slidable in the plunger 10 in sealing engagement with the latter, a rod 22 of reduced cross section extending upward from the driver 13 and out of the plunger 10, and a radial flange or mounting plate 23 on the top end of the rod 22.
  • the carrier 15, not itself seen in FIG. 2 is normally secured to the mounting plate 23 by a threaded fastener, only a threaded central opening in the plate 23 being seen in FIG. 2.
  • a bleeder valve 19 controls a radial opening in the cylinder 11 which is covered by the plunger 10 in the illustrated position of the apparatus.
  • a collar 21 fixed to the plunger 10 under the sealing plate 10 is threadedly connected to a long radial handle 20.
  • the nonillustrated vacuum pump at the end of the line 7 may then be actuated to draw the air from the chamber 1.
  • the tooth remains cool enough so that air occluded in the ceramic mass can escape and is not trapped in partly molten material.
  • the air pressure from the line 12 is increased or the bleeder valve is moved toward the closed position to raise the driver 13 whose movement is transmitted to the work carrier 15 by the rod 22 and the mounting plate 23.
  • the tooth 14 may be raised stepwise or continuously to bring it ultimately into the firing zone bounded by the heating element 2.
  • the driver 13 and associated elements When firing is completed, the driver 13 and associated elements may be lowered, the vacuum broken, and the plunger 10 and sealing plate 10 lowered to the illustrated inoperative position by venting the line 12 to atmosphere.
  • the handle 20 has been found convenient for manually expediting the rise and descent of the plunger 10 and the discharge of the carrier 15 and of its load from the chamber 1. A new cycle can begin.
  • the current to the heating element may be kept cbnstant throughout a sequence of operating cycles.
  • lt' is preferred to provide the bleeder valve 19 and the nonillustrated control valves in the vacuum line 17 and compressed air line 12 with solenoid actuators and return springs so that they can be operated remotely by pushbuttons on the base 6, as is conventional in itself.
  • a furnace for firing a ceramic object which comprises a shell defining a chamber therein, the shell having a closed top and a bottom opening connecting the chamber with the ambient atmosphere, a firing zone adjacent the closed top, a sealing plate mounted outside the chamber in alignment with the chamber opening for pneumatically actuatable movement into sealing engagement with the chamber opening, a pneumatic cylinder receiving compressed air, a piston afiixed to the sealing plate and glidable in the cylinder, the piston being actuated under the pressure of the compressed air to move the sealing plate into said sealing engagement, evacuating means for withdrawing air from the chamber when said opening is sealed, and a carrier for the object between the sealing plate and the chamber opening, the improvement of the sealing plate piston defining an axial bore, a piston glidable in the sealing plate piston bore and afiixed to the carrier, and a constricted orifice in the sealing plate piston for admitting a controlled amount of the compressed air into the axial bore to move the carrier piston in respect of the sealing
  • the sealing plate piston including a bottom closure closing the axial bore, the constricted orifice being defined in the bottom closure.

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  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Clinical Laboratory Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Tunnel Furnaces (AREA)
  • Furnace Details (AREA)
US38721A 1969-05-27 1970-05-19 Vacuum furnace Expired - Lifetime US3641250A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19691926874 DE1926874B1 (de) 1969-05-27 1969-05-27 Elektrisch beheizbarer Brennofen für keramisches Gut

Publications (1)

Publication Number Publication Date
US3641250A true US3641250A (en) 1972-02-08

Family

ID=5735271

Family Applications (1)

Application Number Title Priority Date Filing Date
US38721A Expired - Lifetime US3641250A (en) 1969-05-27 1970-05-19 Vacuum furnace

Country Status (4)

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US (1) US3641250A (de)
AT (1) AT311539B (de)
DE (1) DE1926874B1 (de)
GB (1) GB1301711A (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3860738A (en) * 1971-04-27 1975-01-14 Karl Hintenberger Firing oven for ceramic material
US5544194A (en) * 1993-06-09 1996-08-06 Leybold Durferrit Gmbh Apparatus for degreasing electrically conductive material
US11428469B2 (en) * 2017-02-28 2022-08-30 Labconco Corporation Fuming enclosure with selective heating apparatus

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106322983A (zh) * 2016-04-28 2017-01-11 郑州科佳电炉有限公司 一种义齿软质合金烧结炉

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2966537A (en) * 1958-07-17 1960-12-27 Curtiss Wright Corp High temperature furnace
US2996559A (en) * 1957-06-11 1961-08-15 Heraeus Gmbh W C Method and apparatus for operating a vacuum arc smelting furnace
DE1160777B (de) * 1959-05-15 1964-01-02 Dr Karl Hintenberger Elektrisch beheizbarer Vakuumbrennofen fuer keramisches Gut
US3128326A (en) * 1961-02-28 1964-04-07 Hintenberger Karl Josef Electrically heated vacuum furnace

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1081816B (de) * 1952-05-23 1960-05-12 Dr Karl Hintenberger Elektrisch beheizbarer Brennofen fuer keramisches Gut, insbesondere fuer die Herstellung kuenstlicher Zaehne

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2996559A (en) * 1957-06-11 1961-08-15 Heraeus Gmbh W C Method and apparatus for operating a vacuum arc smelting furnace
US2966537A (en) * 1958-07-17 1960-12-27 Curtiss Wright Corp High temperature furnace
DE1160777B (de) * 1959-05-15 1964-01-02 Dr Karl Hintenberger Elektrisch beheizbarer Vakuumbrennofen fuer keramisches Gut
US3128326A (en) * 1961-02-28 1964-04-07 Hintenberger Karl Josef Electrically heated vacuum furnace

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3860738A (en) * 1971-04-27 1975-01-14 Karl Hintenberger Firing oven for ceramic material
US5544194A (en) * 1993-06-09 1996-08-06 Leybold Durferrit Gmbh Apparatus for degreasing electrically conductive material
US11428469B2 (en) * 2017-02-28 2022-08-30 Labconco Corporation Fuming enclosure with selective heating apparatus

Also Published As

Publication number Publication date
GB1301711A (de) 1973-01-04
DE1926874B1 (de) 1970-04-02
AT311539B (de) 1973-11-26

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