US3850574A - Atmospheric furnace apparatus - Google Patents

Atmospheric furnace apparatus Download PDF

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Publication number
US3850574A
US3850574A US00349323A US34932373A US3850574A US 3850574 A US3850574 A US 3850574A US 00349323 A US00349323 A US 00349323A US 34932373 A US34932373 A US 34932373A US 3850574 A US3850574 A US 3850574A
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US
United States
Prior art keywords
gas
furnace
gas inlet
inlet
atmosphere
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Expired - Lifetime
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US00349323A
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English (en)
Inventor
K Namba
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.)
Tokyo Heat Treating Co
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Tokyo Heat Treating Co
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Publication date
Application filed by Tokyo Heat Treating Co filed Critical Tokyo Heat Treating Co
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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
    • C21D1/767—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material with forced gas circulation; Reheating thereof

Definitions

  • the invention relates to a gas atmosphericfurnace and more particularly to a heat treatment furnace having improved gas inlets.
  • Gas carburizing processes and gas carbonitriding processes are now well known in the art of case hardening of steel articles.
  • a carburizing gas including natural gas or propane gas is fedinto a heat treatment furnace which is hermetically sealed for carburizing an article to be treated under heat within the atmosphere.
  • Gas carbonitriding process invloves heating in a gas atmosphere which comprises the carburizing gas to which is added ammonia gas, and has been developed recently as demonstrated by the disclosure in British Pat. No. 1,034,157 published June 29, 1966.
  • furnaces have been used with the gas carburizing and gas carbonitriding treatments, and recently a continuous furnace also finds its application in these treatments.
  • These furnaces generally include a heating element disposed therein along the opposite side walls and the base, with a fan mounted on the celling.
  • An atmosphere gas is introduced in a horizontal direction toward, the blades of the fan through the fur-- nace wall.
  • the fan stirs the atmosphere gas supplied through the gas inlet while the resulting forced circulation enables heat from the heating element to be conveyed throughoutthe space within the furnace.
  • an object of the invention to provide an atmospheric furnace having improved gas inlets capable of feeding an atmosphere gas toward a stirring fan in a manner which avoids a directional flow of the gas.
  • the atmospheric furnace comprises a gas inlet which opens into the furnace from a passageway formed along and around the shaft of a fan.
  • the passageway communicated with a source of gas through a guide pipe.
  • separatev guide pipes are provided to conduct the respective gases independently and communicate with the passageway.
  • the atmosphere gas fed into the furnace through the gas inlet if diffused as the fan rotates, thereby preventing a directional flow.
  • the fan and its shaft are directly exposed to the flow of the atmosphere gas directed from the guide pipe into the passageway, but the gas in this area is under normal temperature and hence provides a cooling function, which is highly effective to prevent corrosion of these parts by hot atmosphere gas.
  • FIG. 1 is a fragmentary section of the atmospheric furnace according to the invention.
  • FIG. 2 is a fragmentarysection of a modified annospheric furnace of the invention.
  • FIG. 3 is a perspective view of a gas flow deflector shown in FIG. 1.
  • the furnace constructed in accordance with the invention is shown in a cross section through a plane which extends vertically through the center of the fan and viewing toward the discharge opening of an article being treated. While the fumace is illustrated as one used for batch operation, it should be understood that the invention is not limited to such furnace, but is equally applicable to a continuous furnace. Indeed, the illustrated furnace portion may be taken as representing one zone such as a carburizing zone of a continuous furnace.
  • the furnace is generally shown at l and is of conventional design in that it comprises a side wall la, ceiling lb and base 1c, all of which are formed of refractory brick and which are externally covered with a shaped body 2.
  • a plurality of mounts 5 formed of refractory brick are arranged on the base 10 in an array along mutually perp'endicular axes, with a constant spacing between adjacent mounts, and are adapted to carry an article to be treated thereon within the space 7 of the furnace.
  • skid rails not shown in the drawings are provided and guide a tray 16 on which is placed a basket 17 mounting the article being treated.
  • the heat source of an atmospheric furnace usually comprises an electrical heating element, which in the present example is shown at 6a and 6b positioned along the opposite side walls la and the base 1c of the furnace.
  • the heating elements 6b are located intermediate adjacent rows or columns of the mounts 5. While the invention is not lirnitedto any particular construction and lay-out of the electrical heating elements, their arrangement shown is most customary and is known to be desirable.
  • a fan 8 is mounted on the ceiling 1b so as to have its shaft 9 extending therethrough to be connected with an external electric motor 11.
  • a refractory seal 10 is provided around the shaft 9 between the shell 4 and the motor housing.
  • a gas inlet passage way 12 is formed around and along the shaft 9 of the fan, and opens into the space 7 at its one end, while its other end is blocked by the refractory seal 10.
  • a gas supply system 21 is connected with a guide pipe 13a including a gas seal 14a and which is connected with the inlet passage way 12.
  • the atmosphere gas at normal temperature has a cooling effect on the fan 8 and the shaft 9 thereof, which effect prevents corrosion of the parts upon being heated to high temperatures and results in reduced durability of these parts from occurring.
  • the atmosphere gas introduced into the furnace 7 through the gas inlet 12 is exhausted through suitably located outlets, which in the present example are shown at 15, adjacent to the discharge opening of the article being treated.
  • the fluid resistance presented by the heating elements 6 and the loaction of the gas outlets 15 must be deliberately taken into consideration when determining the gas flow, but in the atmospheric furnace of the invention, the uniform diffusion afforded by the fan 8 causes the atmosphere gas to flow toward the base 1c generally in a helical pattern. As a consequence, the speed of flow reduces as the base 1c is approached,
  • the second gas inlet 20 may directly open into the space 7 of the furnace, but preferably is provided with a gas flow deflector 18 at its inner end. As shown in FIG. 3, the deflector 18 has a notch 19 opening in a particular direction. This enables cold gas to be directed to a desired location for recovering the thermal balance within the furnace.
  • FIG. 2 shows a gas inlet arrangement useful in a carbonitriding furnace for mixing more than one .gas therein.
  • Like parts as in FIG. 1 are represented by corresponding reference characters.
  • the reference characters 13b and 14b, not appearing in FIG. 1, represent an additional guide pipe and an additional gas seal, respectively.
  • the arrangement is essentially the same as in FIG. l,'except that a pair of guide pipes 13a and 13b are provided, which are connected with the gas inlet passage way 12 for introducing different gases, for example, carburing gas and ammonia gas, into the furnace.
  • the mixing of these gases at normal temperature involves difficulties because of formation of ammonium carbonate, which are readily avoided by providing the common gas inlet 12 in the furnace.
  • the inlet passage way 12 can be maintained above the temperature at which formation of crystals of ammonium carbonate sphere gas introduced by said first gas inlet, said first gas inlet leading into a passageway formed along and around the shaft of the fan, and a second gas inlet located on the opposite side of the furnace from the first gas inlet, ,said second gas inlet introducing an atmosphere gas of normal temperature to cool the then relatively elevated gas adjacent the second gas inlet to thus maintain an even temperature of the gases within the furnace.
  • a gas atmospheric furnace according to. claim 1 further including a guide pipe connected with the passage way for conducting the atmosphere gas from the first gas inlet therethrough to the passage way.
  • a gas atmospheric furnace according to claim 1 in which said second gas inlet is connected with a gas supply system through a flow rate control valve.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Furnace Details (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Tunnel Furnaces (AREA)
US00349323A 1972-04-07 1973-04-09 Atmospheric furnace apparatus Expired - Lifetime US3850574A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP47034917A JPS5147128B2 (enrdf_load_stackoverflow) 1972-04-07 1972-04-07

Publications (1)

Publication Number Publication Date
US3850574A true US3850574A (en) 1974-11-26

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ID=12427557

Family Applications (1)

Application Number Title Priority Date Filing Date
US00349323A Expired - Lifetime US3850574A (en) 1972-04-07 1973-04-09 Atmospheric furnace apparatus

Country Status (3)

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US (1) US3850574A (enrdf_load_stackoverflow)
JP (1) JPS5147128B2 (enrdf_load_stackoverflow)
DE (1) DE2317769C3 (enrdf_load_stackoverflow)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4086050A (en) * 1975-01-15 1978-04-25 Ipsen Industries International Method and apparatus for gas circulation in a heat treating furnace
US4770630A (en) * 1986-08-23 1988-09-13 Toray Industries, Inc. Heat treatment apparatus
US5224857A (en) * 1991-08-01 1993-07-06 Gas Research Institute Radiant tube arrangement for high temperature, industrial heat treat furnace
US20160052786A1 (en) * 2014-08-25 2016-02-25 Sunshine Pv Corporation Heat treatment method and the product prepared therefrom
US10365043B2 (en) * 2015-04-24 2019-07-30 Koyo Thermo Systems Co., Ltd. Stirring fan for heat treatment apparatus, and heat treatment apparatus including the same

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS53125915A (en) * 1977-04-11 1978-11-02 Tokyo Netsu Shiyori Kougiyou K Homogenous treating method and apparatus

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2039429A (en) * 1931-04-16 1936-05-05 Lydon Timothy Oven and the like with heat circulating means therefor
US2152154A (en) * 1935-01-19 1939-03-28 Birmingham Electr Furnaces Ltd Method of and apparatus for the heat treatment of metals and alloys
US2283982A (en) * 1939-10-07 1942-05-26 Westinghouse Electric & Mfg Co Bell type annealing furnace
US2869848A (en) * 1954-04-09 1959-01-20 British Celanese Filamentary material

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2276614A (en) * 1941-03-13 1942-03-17 Herbert L Grapp Cooling device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2039429A (en) * 1931-04-16 1936-05-05 Lydon Timothy Oven and the like with heat circulating means therefor
US2152154A (en) * 1935-01-19 1939-03-28 Birmingham Electr Furnaces Ltd Method of and apparatus for the heat treatment of metals and alloys
US2283982A (en) * 1939-10-07 1942-05-26 Westinghouse Electric & Mfg Co Bell type annealing furnace
US2869848A (en) * 1954-04-09 1959-01-20 British Celanese Filamentary material

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4086050A (en) * 1975-01-15 1978-04-25 Ipsen Industries International Method and apparatus for gas circulation in a heat treating furnace
US4770630A (en) * 1986-08-23 1988-09-13 Toray Industries, Inc. Heat treatment apparatus
US5224857A (en) * 1991-08-01 1993-07-06 Gas Research Institute Radiant tube arrangement for high temperature, industrial heat treat furnace
US20160052786A1 (en) * 2014-08-25 2016-02-25 Sunshine Pv Corporation Heat treatment method and the product prepared therefrom
US10053364B2 (en) * 2014-08-25 2018-08-21 Sunshine Pv Corporation Heat treatment method and the product prepared therefrom
US10365043B2 (en) * 2015-04-24 2019-07-30 Koyo Thermo Systems Co., Ltd. Stirring fan for heat treatment apparatus, and heat treatment apparatus including the same

Also Published As

Publication number Publication date
DE2317769A1 (de) 1973-10-18
DE2317769B2 (de) 1976-10-28
JPS5147128B2 (enrdf_load_stackoverflow) 1976-12-13
JPS48102013A (enrdf_load_stackoverflow) 1973-12-21
DE2317769C3 (de) 1982-05-06

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