US3917238A - Oven apparatus - Google Patents

Oven apparatus Download PDF

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Publication number
US3917238A
US3917238A US397164A US39716473A US3917238A US 3917238 A US3917238 A US 3917238A US 397164 A US397164 A US 397164A US 39716473 A US39716473 A US 39716473A US 3917238 A US3917238 A US 3917238A
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United States
Prior art keywords
furnace
wall
gaseous mixture
heat
chamber
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Expired - Lifetime
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US397164A
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English (en)
Inventor
Werner Gohring
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Individual
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Individual
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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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C21D1/76—Adjusting the composition of the atmosphere
    • C21D1/763—Adjusting the composition of the atmosphere using a catalyst

Definitions

  • ABSTRACT A device, formaking a furnace atmosphere for the chemico-metallurgical influencing of workpieces during heat treatment, consisting of a reaction chamber surrounded by a heat protection jacket in which fuels, at a temperature between 750 and 1100C, react to form a gaseous mixture, the reaction chamber being arranged outside a heat-treatment furnace space and the gaseous mixture being admitted to the fumace space, is characterised in that the gaseous mixture is heated inside an opening in the wall bounding the inner chamber where heat treatment takes place, by means of a heating device, to a temperature between 750 and 1100C.
  • the invention relates to a device, for establishing a furnace atmosphere for the chemico-metallurgical influencing of workpieces during heat treatment, consisting of a reaction chamber surrounded by a heat protecting jacket, in which fuels react at a temperature between 750 and llC, the reaction chamber being arranged outside a heat treatment furnace space and the gaseous mixture is admitted to the furnace space.
  • One purpose of the invention is to prepare a gaseous mixture suitable as furnace atmosphere, with low outlay on construction, power and maintenance.
  • a further aim of the invention is to reduce the risk of explosion of furnace installations in which inflammable furnace atmospheres are used.
  • the invention furthermore sets out to improve the transfer of carbon from the furnace atmosphere to the workpieces and the ability to judge the effect of the furnace atmosphere on the workpieces undergoing heat treatment.
  • the invention is based on the task of providing a simple and economically operated device making it possible to arrive at the necessary state of reaction of the gaseous mixture in the furnace chamber without troublesome intermediate reactions, and to obtain reliable flame formation at the point where the gaseous mixture is admitted to a furnace space filed with air.
  • the gaseous mixture is heated, within an opening in the wall bounding the inner chamber of the heat treatment, with a heating device to a temperature between 750 and 1 100C.
  • the gaseous mixture passing according to the invention into the furnace chamber has a high content of perceptible heat as a result of being heated as far as the point of entry. It has been recognised that through this energy content the following advantages are obtained:
  • the hot gaseous mixture transfers more carbon to the surface of the workpiece through the cracking of carbon monoxide.
  • free oxygen penetrating into the furnace chamber reacts for preference with the hot gaseous mixture before a layer of oxide is formed on the surface of the workpiece, which also impedes the transfer of carbon.
  • the temperature of the gaseous mixture admitted to the inner chamber of the heat treatment furnace is regulated and monitored at values between 750 and 1 100C. These temperatures are above the ignition temperatures of the gaseous mixtures used as furnace atmosphere'Theassurance is therefore furnished that the hot gaseous mixture entering the furnace chamber, on coming into contact with air, at once forms a flame before an explosive mixture can be produced.
  • the sensible-heat" of the gaseous mixture imparts to the flame particularly stable combustion properties so that the flame burns for a sufficient length of time until the oxygen content in the furnace chamber is so low that there is no'longer any risk of explosion.
  • the heated spot of introduction occupies the smallest possible area of the furnace wall aand practically does not impair the temperature control of the material being heat treated in the furnace, by heat radiation.
  • the gaseous mixture is passed in a heated pipe from the reaction chamber to the opening in the furnace wall.
  • the usual cooling of the gaseous mixture to the reaction chamber is dispensed with.
  • the reaction chamber ends direct in the aperture of the furnace wall.
  • a special supply pipe between the reaction chamber and the furnace wall and its heating device, is dispensed with.
  • a catalyst bed acting as reaction chamber is arranged inside the opening of the heatinsulated wall.
  • the heat insulating wall of the heat treatment furnace is used at the same time as a heat-protecting jacket for a heated catalyst bed. Furthermore, no special chamber and no special heating device is needed for keeping the gaseous mixture warm. With this arrangement of the catalyst bed, the gas outlet points lie within the plane of the geometric shape of the inner chamber of the heat treatment furnace. The gaseous mixture thus passes directly into the inner space of the furnace at the temperature of the heated catalyst bed.
  • the thickness of the heat-insulating outer wall bounding the inner wall of a heat treatment furnace is between 25 and 35cm.
  • the usual length of heated catalyst beds is at least three times this thickness of outer wall.
  • a heating conductor consisting of an electric heating resistance material, traversed by electric current, and in contact with the pieces of catalyst and the reacting gaseous mixture.
  • Carbon passing from the gaseous mixture into the outer surface of the heating conductor quickly travels to the inner surface. There the carbon reacts with the air present and there are no concentrationsof carbon that are detrimental to the material of the heating conductor.
  • FIG. 1 shows a diagram of a heat treatment furnace with a practical form of heating according to the invention of the gaseous mixture on passing through the furnace wall.
  • FIG. 2 shows the particularly advantageous preferential form of execution with the arrangement and development of an electrically heated catalyst bed inside the furnace wall.
  • This inner space contains as necessary heating or cooling means as well as devices for circulating the gases, such,
  • the heat treatment furnace consists of an inner ch amber 1, which is bounded by a continuous heat-insulating wall 6, which at the same time also represents the outer wall of the furnace.
  • a catalyst bed 3 which is heated by electricity.
  • a heating register 8 is accommodated inside the bed and is in direct contactwith the pieces of catalyst 9. Ithas a tubular cross-section.
  • tubular connections 10 leading outwards serve to apply the electric voltage.
  • a fuel or a fuelair mixture is admitted to the heated catalyst bed.
  • the catalyst bed 3 is, according to the invention,
  • the measurement S arises from the distance of the geometric shape of the inner space 1 from that of the surface of the outer wall and is not influenced by protruding or recessed parts ofthe furnace.
  • heating takes place exclusively in the region of the wall 6 (measurement S).
  • the insulating parts (13) protruding from the wall 6 merely serve as protection against heat losses of the heated catalyst bed.
  • hydrocarbon-air mixtures are generally fed to the reaction chamber. There are then produced gaseous mixtures containing carbon monoxide which are able to influence the proportion of carbon in steel workpieces.
  • ammonia, or an ammonia-air mixture it is also possible to make mixtures of gas free from combined oxygen and from carbon.
  • the teaching of the invention is based on recognition for the first time of the advantages of passing a gaseous mixture in the hot state from a reaction chamber into a heat treatment furnace chamber.
  • the arrangement according to the invention of a catalyst bed, its size, form and nature of heating are not obvious having regard to the state of art.
  • Apparatus for the heat treatment of metal workpieces in a controlled atmosphere comprising:
  • a heat-insulating wall surrounding said furnace chamber said wall having an opening therein extending all the way through said wall from the inside of the chamber to the outside of the wall;
  • a catalyst bed disposed in said opening of said wall and extending from the inside line of the furnace wall to the outside line of the furnace wall and substantially filling the opening;
  • v. means for introducing a fuel into said catalyst bed for passage therethrough into said furnace chamber.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Furnace Details (AREA)
  • Tunnel Furnaces (AREA)
US397164A 1972-09-16 1973-09-13 Oven apparatus Expired - Lifetime US3917238A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH1353572A CH579757A5 (fr) 1972-09-16 1972-09-16

Publications (1)

Publication Number Publication Date
US3917238A true US3917238A (en) 1975-11-04

Family

ID=4393264

Family Applications (1)

Application Number Title Priority Date Filing Date
US397164A Expired - Lifetime US3917238A (en) 1972-09-16 1973-09-13 Oven apparatus

Country Status (10)

Country Link
US (1) US3917238A (fr)
AT (1) AT337239B (fr)
CH (1) CH579757A5 (fr)
DD (1) DD107308A5 (fr)
DE (1) DE2346287C2 (fr)
ES (1) ES418741A1 (fr)
FR (1) FR2213352B1 (fr)
GB (1) GB1441758A (fr)
IT (1) IT993200B (fr)
SE (1) SE401935B (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3968957A (en) * 1975-04-09 1976-07-13 Kabushiki Kaisha Fujikoshi Gas carburizing furnace
US4369031A (en) * 1981-09-15 1983-01-18 Thermco Products Corporation Gas control system for chemical vapor deposition system
US20030089426A1 (en) * 2001-07-27 2003-05-15 Poor Ralph Paul Vacuum carburizing with napthene hydrocarbons
US20060180961A1 (en) * 2001-07-27 2006-08-17 Surface Combustion, Inc. Furnace for vacuum carburizing with unsaturated aromatic hydrocarbons

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102009038598B4 (de) * 2009-08-26 2017-06-22 Ipsen International Gmbh Verfahren und Vorrichtung zur Aufbereitung von Prozessgasen für Wärmebehandlungen von metallischen Werkstoffen/Werkstücken in Industrieöfen

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2124573A (en) * 1936-10-21 1938-07-26 Carl I Hayes Enveloping atmosphere control
US2254047A (en) * 1939-06-23 1941-08-26 Westinghouse Electric & Mfg Co Built-in gas generator for industrial furnaces
US2275106A (en) * 1939-02-20 1942-03-03 Carl I Hayes Circulation of heat treatment atmospheres
US3290030A (en) * 1963-09-21 1966-12-06 Goehring Werner Apparatus for the generation of a furnace atmosphere for the heat treatment of metals, especially of steel
US3632979A (en) * 1970-05-25 1972-01-04 Edward J Mccrink Converter for producing controlled atmosphere for heat treating
US3644099A (en) * 1969-09-15 1972-02-22 Holcroft & Co Gas atmosphere generating means for heat-treating furnaces

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE752976C (de) * 1939-04-29 1953-02-02 Westinghouse Electric & Mfg Co Gaserzeuger zur Herstellung nicht entkohlend wirkender Gase
FR1042529A (fr) * 1951-10-02 1953-11-02 Renault Procédé d'obtention d'atmosphère neutre pour le traitement thermique des métaux
FR2112825A5 (en) * 1970-11-10 1972-06-23 Inst Elektrotermicheskogo Obor Atmosphere forming cell - permits simultaneous prod of two distinct atmospheres

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2124573A (en) * 1936-10-21 1938-07-26 Carl I Hayes Enveloping atmosphere control
US2275106A (en) * 1939-02-20 1942-03-03 Carl I Hayes Circulation of heat treatment atmospheres
US2254047A (en) * 1939-06-23 1941-08-26 Westinghouse Electric & Mfg Co Built-in gas generator for industrial furnaces
US3290030A (en) * 1963-09-21 1966-12-06 Goehring Werner Apparatus for the generation of a furnace atmosphere for the heat treatment of metals, especially of steel
US3644099A (en) * 1969-09-15 1972-02-22 Holcroft & Co Gas atmosphere generating means for heat-treating furnaces
US3632979A (en) * 1970-05-25 1972-01-04 Edward J Mccrink Converter for producing controlled atmosphere for heat treating

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3968957A (en) * 1975-04-09 1976-07-13 Kabushiki Kaisha Fujikoshi Gas carburizing furnace
US4369031A (en) * 1981-09-15 1983-01-18 Thermco Products Corporation Gas control system for chemical vapor deposition system
US20030089426A1 (en) * 2001-07-27 2003-05-15 Poor Ralph Paul Vacuum carburizing with napthene hydrocarbons
US6991687B2 (en) * 2001-07-27 2006-01-31 Surface Combustion, Inc. Vacuum carburizing with napthene hydrocarbons
US20060180961A1 (en) * 2001-07-27 2006-08-17 Surface Combustion, Inc. Furnace for vacuum carburizing with unsaturated aromatic hydrocarbons
US7204952B1 (en) 2001-07-27 2007-04-17 Surface Combustion, Inc. Vacuum furnace for carburizing with hydrocarbons
US7267793B2 (en) 2001-07-27 2007-09-11 Surface Combustion, Inc. Furnace for vacuum carburizing with unsaturated aromatic hydrocarbons

Also Published As

Publication number Publication date
IT993200B (it) 1975-09-30
ATA753373A (de) 1976-10-15
ES418741A1 (es) 1976-06-16
GB1441758A (en) 1976-07-07
AT337239B (de) 1977-06-27
FR2213352B1 (fr) 1976-05-07
DE2346287C2 (de) 1984-06-14
SE401935B (sv) 1978-06-05
DE2346287A1 (de) 1974-05-02
FR2213352A1 (fr) 1974-08-02
CH579757A5 (fr) 1976-09-15
DD107308A5 (fr) 1974-07-20

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