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WO1994016278A1 - Vacuum furnace for thermal treatment - Google Patents

Vacuum furnace for thermal treatment Download PDF

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Publication number
WO1994016278A1
WO1994016278A1 PCT/PL1993/000001 PL9300001W WO9416278A1 WO 1994016278 A1 WO1994016278 A1 WO 1994016278A1 PL 9300001 W PL9300001 W PL 9300001W WO 9416278 A1 WO9416278 A1 WO 9416278A1
Authority
WO
WIPO (PCT)
Prior art keywords
furnace
elements
segments
heating chamber
vacuum furnace
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.)
Ceased
Application number
PCT/PL1993/000001
Other languages
French (fr)
Inventor
Józef OLEJNIK
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.)
Seco/warwick Spolka Z Oo (ltd)
Original Assignee
Seco/warwick Spolka Z Oo (ltd)
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Seco/warwick Spolka Z Oo (ltd) filed Critical Seco/warwick Spolka Z Oo (ltd)
Publication of WO1994016278A1 publication Critical patent/WO1994016278A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • 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
    • C21D1/773—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material under reduced pressure or vacuum
    • 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
    • F27B5/06—Details, accessories or equipment specially adapted for furnaces of these types
    • F27B5/14—Arrangements of heating devices
    • 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
    • F27B5/06—Details, accessories or equipment specially adapted for furnaces of these types
    • F27B5/16—Arrangements of air or gas supply devices
    • 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
    • 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
    • F27B5/06—Details, accessories or equipment specially adapted for furnaces of these types
    • F27B5/16—Arrangements of air or gas supply devices
    • F27B2005/161—Gas inflow or outflow
    • F27B2005/162—Gas inflow or outflow through closable or non-closable openings of the chamber walls
    • 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
    • F27B5/06—Details, accessories or equipment specially adapted for furnaces of these types
    • F27B5/16—Arrangements of air or gas supply devices
    • F27B2005/166—Means to circulate the atmosphere
    • F27B2005/167—Means to circulate the atmosphere the atmosphere being recirculated through the treatment chamber by a turbine

Definitions

  • the object of the present invention is a vacuum furnace for thermal treatment, particularly for quenching metal workpieces made of various grades of steel and alloys. It may be used for annealing and soldering.
  • the objects under thermal treatment are placed in a thermally insulated heating chamber and heated by convection until they reach the temperature of 700o - 900o C; whereas in the case of the vacuum furnace - the austenitizing temperature.
  • the charge is cooled by a neutral cooling gas which is circulated under pressure through the heating chamber.
  • the process of heating cooling is performed by two independent structural elements of the furnace, namely: heating elements and gas collectors.
  • Application P 292743 presented a solution where the collectors were installed inside the heating chamber and placed evenly on the perimeter of the charge outline. As far as the heating elements are concerned, a well-known and classic solution was used.
  • the West German patent No. 3736502 presented a construction of a furnace gas collectors were thin-walled tubular heating elements of the diameter of 60 - 120 mm, made of C-C composite materials. In this solution gas collectors were placed evenly round the charge .
  • a furnace was designed in which one structural element functions as both the heating element and gas collector.
  • the vacuum furnace for thermal treatment has got on the perimeter of the heating chamber flat rectangular elements made of a resistive heating material which secures dimensional and thermal stability at temperatures up to 1 400o C.
  • the edges of these elements, escept for the one situated at the back wall of the furnace, are sealed with a ceramic material.
  • the seal is embedded on a flexible bracket made of a heating material; preferably in the form of a thin-walled channel-bar.
  • the seal serves as a current insulator at the spot where the element is fixed to the insulation wall of the furnace.
  • the elements are also connected to each other by connecting links made of materials of good electric conductivity in order to obtain an electric circuit.
  • Each of the flat elements is divided into segments of equal size so that a slot thus created between the segments would constitute an electric insulation of each individual segment.
  • the number of segments depends on the scheme of connections employed for the current supply to the heating chamber. It is advisable to assign two segments to one phase.
  • the slots between the segments constitute the collector's cooling slot nozzles.
  • the space between the internal wall of the heating chamber and the flat rectangular multi-segment elements installed there constitutes the gas collector. From the gas collector the gas is forced into the work space of the heating chamber through apertures made in individual segments and through the slot nozzles. The apertures are placed evenly on the perimeter of the charge outline.
  • a furnace equipped with an element f nctioning both as a heater and a gas collector makes it possible to increase the work space of the heating chamber without increasing the overall dimensions of the furnace.
  • a large area of the flat elements divided into segments allows us to obtain a very homogeneous thermal field.
  • the gas flowing through the nozzles in the segments and slots between the segments cools the charge quickly and evenly.
  • Fig.1 shows an end view
  • Fig.3 detail of mounting to insulation wall together with the seal.
  • the furnace for thermal treatment has in the heating chamber four flat rectangular elements 1 made of C-C composite materials.
  • the elements 1 have on their edges a seal 2 made of ceramic tubes (except for the part situated at the back wall of the furnace).
  • the seal 2 is a current insulator between the element 1 and the outer furnace body at the spot where it is fixed to the insulation wall. It is embedded on a flexible racket 3 in the form af a thin-walled channel-bar of C-C composite.
  • Elements 1 are connected with each other by electric conductors 4 in order to produce an electric circuit.
  • Each of the elements 1 is divided into six equal segments 1a which create slots 5 of the width of 2,5 mm constituting electric insulation.
  • the slot 5 nozzle of the cooling gas collestor.
  • two apertures 6 are made where the nozzles are mounted.
  • the apertures 6 are so placed as to create a uniform grid on the perimeter of the charge outline.
  • the space 7 of the width of 5 mm between the insulation wall of the furnace and elements 1 fixed to it constitutes the gas collector from which the cooling gas is forced to the charge space through slots 5 and apertures 6.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Furnace Details (AREA)

Abstract

The object of the present invention is a vacuum furnace for thermal treatment, particularly for quenching of metal workpieces made of various grades of steel and alloys. According to the invention the furnace has on the perimeter of the heating chamber flat rectangular elements (1) made of a resistive heating material which secures dimensional and thermal stability. Except for the element situated at the back wall of the furnace, the elements (1) have on their edges a seal (2) of ceramic material, being at the time a current insulator. They are connected by links (4) of a material of good electric conductivity. Each element (1) is divided into segment (1a) of equal size so that a slot (5) is created, insulating each of them electrically. Apertures (6) are made in each segment to allow the flow of gas. The space between the internal wall of the heating chamber and the elements (1) mounted on it is the gas collector (7) from which the cooling gas is forced into the work space of the heating chamber through aperture (6) and slots (5). The furnace is equipped with an element being at the same time a heater and gas collector which makes it possible to increase the work space of the heating chamber without increasing the overall dimensions of the furnace.

Description

VACUUM FURNACE FOR THERMAL TREATMENT
The object of the present invention is a vacuum furnace for thermal treatment, particularly for quenching metal workpieces made of various grades of steel and alloys. It may be used for annealing and soldering.
In standard vacuum furnaces the objects under thermal treatment are placed in a thermally insulated heating chamber and heated by convection until they reach the temperature of 700º - 900º C; whereas in the case of the vacuum furnace - the austenitizing temperature. Next, the charge is cooled by a neutral cooling gas which is circulated under pressure through the heating chamber.
In general, the process of heating cooling is performed by two independent structural elements of the furnace, namely: heating elements and gas collectors.
Application P 292743 presented a solution where the collectors were installed inside the heating chamber and placed evenly on the perimeter of the charge outline. As far as the heating elements are concerned, a well-known and classic solution was used.
The West German patent No. 3736502 presented a construction of a furnace gas collectors were thin-walled tubular heating elements of the diameter of 60 - 120 mm, made of C-C composite materials. In this solution gas collectors were placed evenly round the charge .
The drawback of the most frequently employed solution is that independent heating elements and gas collectors increase the overail dimensions of a furnace or limit the work space of the heating chamber. Such disadvantages were partially avoided in the
Figure imgf000004_0001
of the furnace without limiting the work space of the heating chamber and obtaining an even temperature in the whole chamber as well as fast and good cooling, a furnace was designed in which one structural element functions as both the heating element and gas collector.
In the present invention the vacuum furnace for thermal treatment has got on the perimeter of the heating chamber flat rectangular elements made of a resistive heating material which secures dimensional and thermal stability at temperatures up to 1 400º C. The edges of these elements, escept for the one situated at the back wall of the furnace, are sealed with a ceramic material. The seal is embedded on a flexible bracket made of a heating material; preferably in the form of a thin-walled channel-bar.
At the same time, the seal serves as a current insulator at the spot where the element is fixed to the insulation wall of the furnace.
The elements are also connected to each other by connecting links made of materials of good electric conductivity in order to obtain an electric circuit.
Each of the flat elements is divided into segments of equal size so that a slot thus created between the segments would constitute an electric insulation of each individual segment. The number of segments depends on the scheme of connections employed for the current supply to the heating chamber. It is advisable to assign two segments to one phase. At the same time, the slots between the segments constitute the collector's cooling slot nozzles. The space between the internal wall of the heating chamber and the flat rectangular multi-segment elements installed there constitutes the gas collector. From the gas collector the gas is forced into the work space of the heating chamber through apertures made in individual segments and through the slot nozzles. The apertures are placed evenly on the perimeter of the charge outline.
A furnace equipped with an element f nctioning both as a heater and a gas collector makes it possible to increase the work space of the heating chamber without increasing the overall dimensions of the furnace. A large area of the flat elements divided into segments allows us to obtain a very homogeneous thermal field.
The gas flowing through the nozzles in the segments and slots between the segments cools the charge quickly and evenly.
The object of the present invention is shown in enclosed figures.
Fig.1 shows an end view,
Fig.2 - cross-sectional view of the furnace,
Fig.3 - detail of mounting to insulation wall together with the seal.
The furnace for thermal treatment has in the heating chamber four flat rectangular elements 1 made of C-C composite materials. The elements 1 have on their edges a seal 2 made of ceramic tubes (except for the part situated at the back wall of the furnace). At the same time, the seal 2 is a current insulator between the element 1 and the outer furnace body at the spot where it is fixed to the insulation wall. It is embedded on a flexible racket 3 in the form af a thin-walled channel-bar of C-C composite. Elements 1 are connected with each other by electric conductors 4 in order to produce an electric circuit.
Each of the elements 1 is divided into six equal segments 1a which create slots 5 of the width of 2,5 mm constituting electric insulation. At the same time, the slot 5 nozzle of the cooling gas collestor. In each of the segments 1a two apertures 6 are made where the nozzles are mounted. The apertures 6 are so placed as to create a uniform grid on the perimeter of the charge outline. The space 7 of the width of 5 mm between the insulation wall of the furnace and elements 1 fixed to it constitutes the gas collector from which the cooling gas is forced to the charge space through slots 5 and apertures 6.

Claims

1. The vacuum furnace for thermal treatment, particularly for quenching, with an insulated cylindrical heating chamber equipped with heating elements and cooling gas collector, is characterized in that on the perimeter of the heating chamber it has flat rectangular elements (1) made of a resistive heating material whose edges, except for the element situated at the back wall of the furnace, have a seal (2) of ceramic material being at the same time a current insulation at the spot where the element (1) is fixed to the insulation wall of the furnace and which are connected with each other by connecting links (4) of a material of good electirc conductivity; and each of the elements (1) is divided into segments (1a) of equal size so that a slot is created between them which constitutes an electric insulation of each segment (1a) and which functions at the same time as a cooling slot nozzle; the apertures (6) are made in each of the segments and the space created between the insulation wall of the furnace and the flat rectangular element (1) is a gas collector (7) from which the cooling gas is forced into the charge space through the apertures (6) and slots (5).
2. The vacuum furnace according to claim 1 is characterized in that the flat rectangular element (1) is divided into such a number of segments (1a) that each phase of current supply is assigned two segments.
3. The vacuum furnace according to claim 1 is characterized in that the apertures (6) in the segments (1a) are placed evenly on the perimeter of the charge outline.
4. The vacuum furnace according to claim 1 is characterized in that seal (2) is embedded in a flexible bracket (3) made of a resistive heating material in the form of a thin-walled channel-bar.
5. The vacuum furnace according to claim 1 is characterized in that the flat rectangular elements (1) maintain dimensional abd thermal stability at the temperature of up 1400º C.
PCT/PL1993/000001 1993-01-14 1993-03-04 Vacuum furnace for thermal treatment Ceased WO1994016278A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
PL29743993A PL170386B1 (en) 1993-01-14 1993-01-14 Vacuum-type heat treatment furnace
PLP.297439 1993-01-14

Publications (1)

Publication Number Publication Date
WO1994016278A1 true WO1994016278A1 (en) 1994-07-21

Family

ID=20059371

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/PL1993/000001 Ceased WO1994016278A1 (en) 1993-01-14 1993-03-04 Vacuum furnace for thermal treatment

Country Status (2)

Country Link
PL (1) PL170386B1 (en)
WO (1) WO1994016278A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0884547A1 (en) * 1997-05-19 1998-12-16 Ipsen International, Inc. Heating element support for an electric heat treating furnace
DE10248506A1 (en) * 2001-10-12 2003-06-26 Wems Inc Vacuum oven used in clean room, has vacuum valve which releasably couples hollow oven casing to external vacuum source and door which covers opening of oven casing

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4799881A (en) * 1986-10-16 1989-01-24 Grier-Mcguire Inc. "Twist-lock" gas nozzle for a heat treating furnace
EP0313889A1 (en) * 1987-10-28 1989-05-03 Degussa Aktiengesellschaft Vacuum furnace for the heat treatment of metallic work-pieces
DE4113458A1 (en) * 1991-04-25 1992-10-29 Iva Industrieoefen Verfahren A Vacuum furnace for heat treatment of metal parts - has cover walls inside heating chamber to confine carriage area to minimal size thereby increasing cooling effects of blown gas

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4799881A (en) * 1986-10-16 1989-01-24 Grier-Mcguire Inc. "Twist-lock" gas nozzle for a heat treating furnace
EP0313889A1 (en) * 1987-10-28 1989-05-03 Degussa Aktiengesellschaft Vacuum furnace for the heat treatment of metallic work-pieces
DE4113458A1 (en) * 1991-04-25 1992-10-29 Iva Industrieoefen Verfahren A Vacuum furnace for heat treatment of metal parts - has cover walls inside heating chamber to confine carriage area to minimal size thereby increasing cooling effects of blown gas

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0884547A1 (en) * 1997-05-19 1998-12-16 Ipsen International, Inc. Heating element support for an electric heat treating furnace
US5930285A (en) * 1997-05-19 1999-07-27 Ipsen International, Inc. Heating element support for an electric heat treating furnace
DE10248506A1 (en) * 2001-10-12 2003-06-26 Wems Inc Vacuum oven used in clean room, has vacuum valve which releasably couples hollow oven casing to external vacuum source and door which covers opening of oven casing
DE10248506B4 (en) * 2001-10-12 2005-06-23 WEMS, Inc., Howthorne Vacuum furnace, system containing it, and method of using it
US6914218B2 (en) 2001-10-12 2005-07-05 Wems, Inc. Vacuum oven, system incorporating the same and method of using the same

Also Published As

Publication number Publication date
PL170386B1 (en) 1996-12-31
PL297439A1 (en) 1994-07-25

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