EP0195077A1 - A process for heat treatment of workpieces and a heat treatment installation suitable for such a process - Google Patents

A process for heat treatment of workpieces and a heat treatment installation suitable for such a process

Info

Publication number
EP0195077A1
EP0195077A1 EP19850905006 EP85905006A EP0195077A1 EP 0195077 A1 EP0195077 A1 EP 0195077A1 EP 19850905006 EP19850905006 EP 19850905006 EP 85905006 A EP85905006 A EP 85905006A EP 0195077 A1 EP0195077 A1 EP 0195077A1
Authority
EP
European Patent Office
Prior art keywords
heat treatment
furnace
workpieces
charges
rotating hearth
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.)
Withdrawn
Application number
EP19850905006
Other languages
German (de)
French (fr)
Inventor
Tomas Barkman
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.)
Volvo AB
Original Assignee
Volvo AB
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 Volvo AB filed Critical Volvo AB
Publication of EP0195077A1 publication Critical patent/EP0195077A1/en
Withdrawn legal-status Critical Current

Links

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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • 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
    • C21D9/0037—Rotary furnaces with vertical axis; Furnaces with rotating floor

Definitions

  • the present invention relates to a process for heat treatment of workpieces of steel or of other alloys, corresponding to different heat treatment profiles, said profile being the same within each charge of workpieces, in an automatic heat treatment installation, whereby the workpieces having the same heat treatment profile are collected in workpiece charges and the workpiece charges are subjected to different heat treatment conditions in a heat treat ⁇ ment furnace, said heat treatment conditions being determined by the furnace atmosphere, the treatment temperature and the treating time.
  • the passage times for the charges are usually fixed, but can some times be adjusted for certain operating conditions.
  • the heat treatment profile determines, as is known, the depth of treatment, for example the case depth which the specifications for the workpiece require.
  • the term heat treatment encompasses both purely thermal treatment and chemical treatment with replacement of substances, in particular carbonization treatment.
  • the workpiece charges are treated in a continuous discharge furnace.
  • the varying heat treatment conditions are set by changing the furnace atmosphere and/or the treatment temperature, since the passage time is preset by the fixed speed of the charges passing in sequence.
  • the conditions are similar when a chamber furnace is used as a heat treatment furnace.
  • the workpieces are held for a predetermined period in order to achieve a given heat treatment profile. If one wishes to achieve different heat treatment profiles with a single furnace, the furnace atmosphere must be appropriately regulated or the temperature must be changed. These regulating procedures require significant down-time periods. This is especially true for carbonization treatment.
  • the heat treatment installations used in the known proces ⁇ ses have for setting the heat treatment condition regulating and control equipment for influencing the furnace atmosphere or the treatment temperature.
  • the purpose of the invention is to conduct the process of the type described, so that the setting of different heat treatment conditions for individual charges does not require changing of the furnace atmosphere and/or the treatment temperature.
  • the invention has the further purpose of providing a particularly simple and reliable heat treatment installation for the process according to the invention.
  • the invention provides a process- whereby the workpiece charges are treated in a rotating hearth furnace.
  • the differing travel paths can be achieved in a particularly simple manner if the workpiece charges are introduced into the rotating hearth furnace through an entry lock and removed from the rotating hearth furnace via at least one exit lock. It lies within the scope of the invention, however, to introduce and remove the charges via a single lock if the treatment cycles so permit.
  • the different distances travelled can be achieved with a rotating hearth rotating in one direction or with a reversible rotating hearth. It is immediately possible to carry out the process according to the invention in such a manner as to be applicable to widely varying workpiece charges and so as to be able to set the appropriate distance travelled automatically from charge to charge.
  • the distance travelled can be controlled with the aid of a computer control means in response to machine readable charge data on the workpiece charges.
  • the invention teaches the procedure of collecting the pieces requiring a particular heat treatment profile and thus a particular case depth, into a single charge and transporting them in this charge through the rotating hearth furnace.
  • the passage through the rotating hearth furnace is regulated so that the staying time to achieve a particular heat treatment profile and thus a particular treatment depth is not exceeded.
  • a workpiece charge will be removed from the furnace at the moment when the heat treatment profile has just been reached.
  • the rotating hearth furnace can then be loaded, for example, via the entry lock. Loading and unloading of the furnace can be controlled so that the turning of the turn-table is kept to a minimum. This is easily achieved by means of a computer.
  • the entire flow of workpieces through the heat treatment installation is controlled by an optimizing calculator for the rotating hearth furnace, depending on the number or workpieces to be treated and the heat treatment profile/treatment depth. If, for example, a controlling computer determines, when looking at the coming flow of materials over a long period of time, that the heat treatment temperature and composition of the furnace atmosphere should be changed to optimize energy consumption, then this should result in an operative resetting. Otherwise the process proceeds from setting to setting according to the invention.
  • the advantages achieved with regard to the process lie in the fact that the composition of the furnace atmosphere and/or the treatment temperature need not be changed in the process according to the invention, thus eliminating the disruptive down-time described above. This ineffective time is reduced almost to the turning time of the turn-table in the rotating hearth furnace.
  • An installation for carrying out the process according to the invention which works with a heat treatment furnace and equipment for setting the heat treatment conditions is characterized in that the heat treatment furnace is a rotating hearth furnace, the furnace atmosphere and the treatment temperature which can be differently adjusted during operation and can be kept constant in the thus adjusted state with the aid of control and/or regulating equipment, and that the equipment operates to set the heat treatment conditions of the rotating hearth and directs the workpiece charges having different heat treatment profiles to different travel paths.
  • the invention will be described below in more detail with reference to a drawing serving only as an example.
  • the single drawing shows an installation for carrying out the process described.
  • the example relates to a carbonization furnace, but applies correspondingly to other heat treatment installations.
  • the primary components of the carbonization installation include a carbonization furnace 1 and equipment 2 for setting the carbonization conditions.
  • the carbonization furnace 1 is a rotating hearth carbonization furnace.
  • the device is designed so that the equipment 3 in the figure adjusts the carbonization atmosphere and the carbonization temperature independently and holds the thus adjusted states constant with the aid of control and/or regulator equipment.
  • the equipment 2 for setting the carbonization conditions is indicated at the bottom of the figure and works on the turn-table. The arrangement is such that this equipment 2 directs workpiece charges with different carbonization profiles to different travel paths. This equipment detects charge data readable on the workpiece charges as indicated by the dash-dot line.
  • the turn-table 4 can rotate forwards and backwards.
  • the figure indicates that a preheating furnace 5 and a heat-up chamber 6 can be added to the rotating hearth furnace and that these two additions can be joined to each other via a lock 7 and that the rotating hearth furnace 1 and the heat-up chamber 6 are connected via an entry lock 8.
  • the example shows an exit lock 9 which is connected to a diffusion chamber 10 and which can be connected via a further lock 11 to an oil bath 12 for example.
  • a manipulator 13 and a hardening press 14 can be connected to the furnace 4.

Abstract

Dans un procédé de traitement thermique de pièces à usiner correspondant des profils divers de traitement thermique, ces profils étant les mêmes pour chaque charge de pièces à usiner, les pièces à usiner ayant le même profil de traitement thermique sont rassemblées en charges de pièces à usiner, et ses charges de pièces à usiner sont soumises à des conditions diverses de traitement thermique dans un four de traitement thermique. Les conditions de traitement thermique sont détérminées par l'atmosphère du four, par la température de traitement et par la durée du traitement. Les charges de pièces à usiner sont traitées dans un four à sole rotative (1) dans lequel l'atmosphère du four et la température de traitement sont maintenues constantes. Les différentes conditions de traitement thermique sont obtenues en variant les parcours, donc la durée du traitement, des charges de pièces à usiner dans le four à sole rotative. Un dispositif pour appliquer le procédé est pourvu de l'équipement approprié (2) pour ajuster les conditions de traitement thermique s'exerçant sur la sole rotative.In a process for the heat treatment of workpieces corresponding to various heat treatment profiles, these profiles being the same for each load of workpieces, the workpieces having the same heat treatment profile are grouped into workpiece loads , and its loads of workpieces are subjected to various heat treatment conditions in a heat treatment oven. The heat treatment conditions are determined by the atmosphere of the furnace, by the treatment temperature and by the duration of the treatment. The workpiece loads are processed in a rotary hearth furnace (1) in which the furnace atmosphere and the processing temperature are kept constant. The different heat treatment conditions are obtained by varying the paths, therefore the duration of the treatment, of the loads of workpieces in the rotary hearth furnace. A device for applying the process is provided with the appropriate equipment (2) for adjusting the heat treatment conditions exerted on the rotary floor.

Description

A process for heat treatment of workpieces and a heat treatment installation suitable for such a process
The present invention relates to a process for heat treatment of workpieces of steel or of other alloys, corresponding to different heat treatment profiles, said profile being the same within each charge of workpieces, in an automatic heat treatment installation, whereby the workpieces having the same heat treatment profile are collected in workpiece charges and the workpiece charges are subjected to different heat treatment conditions in a heat treat¬ ment furnace, said heat treatment conditions being determined by the furnace atmosphere, the treatment temperature and the treating time. In automatic heat treatment furnaces, the passage times for the charges are usually fixed, but can some times be adjusted for certain operating conditions. The heat treatment profile determines, as is known, the depth of treatment, for example the case depth which the specifications for the workpiece require. The term heat treatment encompasses both purely thermal treatment and chemical treatment with replacement of substances, in particular carbonization treatment.
Within the scope of the known processes of this type used in practice, the workpiece charges are treated in a continuous discharge furnace. The varying heat treatment conditions are set by changing the furnace atmosphere and/or the treatment temperature, since the passage time is preset by the fixed speed of the charges passing in sequence. The conditions are similar when a chamber furnace is used as a heat treatment furnace. Within the scope of the known processes, using either a continuous discharge furnace or a chamber furnace, the workpieces are held for a predetermined period in order to achieve a given heat treatment profile. If one wishes to achieve different heat treatment profiles with a single furnace, the furnace atmosphere must be appropriately regulated or the temperature must be changed. These regulating procedures require significant down-time periods. This is especially true for carbonization treatment. The heat treatment installations used in the known proces¬ ses have for setting the heat treatment condition regulating and control equipment for influencing the furnace atmosphere or the treatment temperature.
The purpose of the invention is to conduct the process of the type described, so that the setting of different heat treatment conditions for individual charges does not require changing of the furnace atmosphere and/or the treatment temperature. The invention has the further purpose of providing a particularly simple and reliable heat treatment installation for the process according to the invention.
To achieve these purposes, the invention provides a process- whereby the workpiece charges are treated in a rotating hearth furnace. The differing travel paths can be achieved in a particularly simple manner if the workpiece charges are introduced into the rotating hearth furnace through an entry lock and removed from the rotating hearth furnace via at least one exit lock. It lies within the scope of the invention, however, to introduce and remove the charges via a single lock if the treatment cycles so permit. The different distances travelled can be achieved with a rotating hearth rotating in one direction or with a reversible rotating hearth. It is immediately possible to carry out the process according to the invention in such a manner as to be applicable to widely varying workpiece charges and so as to be able to set the appropriate distance travelled automatically from charge to charge. Furthermore, according to the invention, the distance travelled can be controlled with the aid of a computer control means in response to machine readable charge data on the workpiece charges.
In other words, the invention teaches the procedure of collecting the pieces requiring a particular heat treatment profile and thus a particular case depth, into a single charge and transporting them in this charge through the rotating hearth furnace. The passage through the rotating hearth furnace is regulated so that the staying time to achieve a particular heat treatment profile and thus a particular treatment depth is not exceeded. In other words, when there are charges in the rotating hearth furnace which require different heat treatment profiles, a workpiece charge will be removed from the furnace at the moment when the heat treatment profile has just been reached. The rotating hearth furnace can then be loaded, for example, via the entry lock. Loading and unloading of the furnace can be controlled so that the turning of the turn-table is kept to a minimum. This is easily achieved by means of a computer. The entire flow of workpieces through the heat treatment installation is controlled by an optimizing calculator for the rotating hearth furnace, depending on the number or workpieces to be treated and the heat treatment profile/treatment depth. If, for example, a controlling computer determines, when looking at the coming flow of materials over a long period of time, that the heat treatment temperature and composition of the furnace atmosphere should be changed to optimize energy consumption, then this should result in an operative resetting. Otherwise the process proceeds from setting to setting according to the invention.
The advantages achieved with regard to the process lie in the fact that the composition of the furnace atmosphere and/or the treatment temperature need not be changed in the process according to the invention, thus eliminating the disruptive down-time described above. This ineffective time is reduced almost to the turning time of the turn-table in the rotating hearth furnace. An installation for carrying out the process according to the invention which works with a heat treatment furnace and equipment for setting the heat treatment conditions is characterized in that the heat treatment furnace is a rotating hearth furnace, the furnace atmosphere and the treatment temperature which can be differently adjusted during operation and can be kept constant in the thus adjusted state with the aid of control and/or regulating equipment, and that the equipment operates to set the heat treatment conditions of the rotating hearth and directs the workpiece charges having different heat treatment profiles to different travel paths.
The invention will be described below in more detail with reference to a drawing serving only as an example. The single drawing shows an installation for carrying out the process described. The example relates to a carbonization furnace, but applies correspondingly to other heat treatment installations.
The primary components of the carbonization installation include a carbonization furnace 1 and equipment 2 for setting the carbonization conditions. The carbonization furnace 1 is a rotating hearth carbonization furnace. The device is designed so that the equipment 3 in the figure adjusts the carbonization atmosphere and the carbonization temperature independently and holds the thus adjusted states constant with the aid of control and/or regulator equipment. The equipment 2 for setting the carbonization conditions is indicated at the bottom of the figure and works on the turn-table. The arrangement is such that this equipment 2 directs workpiece charges with different carbonization profiles to different travel paths. This equipment detects charge data readable on the workpiece charges as indicated by the dash-dot line. The turn-table 4 can rotate forwards and backwards. The figure indicates that a preheating furnace 5 and a heat-up chamber 6 can be added to the rotating hearth furnace and that these two additions can be joined to each other via a lock 7 and that the rotating hearth furnace 1 and the heat-up chamber 6 are connected via an entry lock 8. On the other side the example shows an exit lock 9 which is connected to a diffusion chamber 10 and which can be connected via a further lock 11 to an oil bath 12 for example.
It is to be. understood that additional equipment can be provided. For example, a manipulator 13 and a hardening press 14 can be connected to the furnace 4.

Claims

1. Process for heat treating of workpieces corresponding to different heat treatment profiles, said profiles being the same within each charge of workpieces, in an automatic heat treatment installa¬ tion, whereby the workpieces having the same heat treatment profile are collected in workpiece charges and the workpiece charges are subjected to different heat treatment conditions in a heat treatment furnace, said heat treatment conditions being determined by the furnace atmosphere, the treatment temperature and the treatment time, characterized in that the workpiece charges are treated in a rotating hearth furnace in which the furnace atmosphere and the treatment temperature are kept constant, and that the differing heat treatment conditions are achieved by varying the travel path and thus the treatment time of the work¬ piece charges in the rotating hearth furnace.
2. Process according to Claim 1, characterized in that the workpiece charges are introduced into the rotating hearth furnace through an entry lock and are removed from the rotating hearth furnace via at least one exit lock.
3. Process according to any one of Claims 1 or 2, characterized in that the travel paths are achieved by rotating the rotating hearth in one direction or by reversing the direction.
4. Process according to any one of Claims 1-3, characterized in that the travel path is controlled with the aid of a computer control means in response to machine readable charge data on the workpiece charges.
5. Heat treatment installation for carrying out the process according to any one of Claims 1-4., with a heat treatment, furnace and equipment for setting the heat treatment conditions, characterized in that the heat treatment furnace (1) is a rotating hearth furnace, the furnace atmosphere and the treatment temperature of which can be differently adjusted during the operation and can be kept constant in the thus adjusted state with the aid of control and/or regulating equipment, and that the equipment (2) operates to set the heat treatment conditions of the rotating hearth and direct the workpiece charges having different heat treatment profiles to different travel paths.
EP19850905006 1984-09-27 1985-09-27 A process for heat treatment of workpieces and a heat treatment installation suitable for such a process Withdrawn EP0195077A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19843435376 DE3435376C2 (en) 1984-09-27 1984-09-27 Process for heat treatment of workpieces
DE3435376 1984-09-27

Publications (1)

Publication Number Publication Date
EP0195077A1 true EP0195077A1 (en) 1986-09-24

Family

ID=6246440

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19850905006 Withdrawn EP0195077A1 (en) 1984-09-27 1985-09-27 A process for heat treatment of workpieces and a heat treatment installation suitable for such a process

Country Status (4)

Country Link
EP (1) EP0195077A1 (en)
JP (1) JPH08967B2 (en)
DE (1) DE3435376C2 (en)
WO (1) WO1986002103A1 (en)

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Publication number Priority date Publication date Assignee Title
DE3441338A1 (en) * 1984-11-13 1986-05-15 Ipsen Industries International Gmbh, 4190 Kleve Process for heat-treating metallic workpieces, using a straight-flow or continuous pusher-type furnace, and equipment for carrying out this process
DE3640325C1 (en) * 1986-11-26 1988-02-04 Ipsen Ind Internat Gmbh Device for the heat treatment of metallic workpieces in a carbonizing atmosphere
US4763880A (en) * 1987-04-03 1988-08-16 Holcroft/Loftus Inc. Rotary hearth multi-chamber, multi-purpose furnace system
US5324366A (en) * 1991-08-09 1994-06-28 Caterpillar Inc. Heat treat furnace system for performing different carburizing processes simultaneously
DE4316841A1 (en) * 1993-05-19 1994-11-24 Aichelin Gmbh Device for the heat treatment of metallic workpieces
DE29505496U1 (en) * 1995-03-31 1995-06-01 Ipsen Ind Int Gmbh Device for the heat treatment of metallic workpieces under vacuum
ES2163791T3 (en) * 1996-08-30 2002-02-01 Franz Hillingrathner ROTARY OVEN FOR THE TREATMENT OF WORK PIECES.
DE19919738A1 (en) * 1999-01-29 2000-08-03 Loi Thermprocess Gmbh Continuous furnace with a device for quenching workpieces and quenching processes
DE10310739A1 (en) * 2002-03-27 2003-10-09 Loi Thermprocess Gmbh Device for heat treating workpieces has an opening for charging/discharging in the outer wall of a rotary furnace in a last treatment zone

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US2013905A (en) * 1933-02-04 1935-09-10 Jr James L Adams Circular ingot heating furnace
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DE971225C (en) * 1943-10-13 1958-12-31 Aeg Rotary hearth furnace with attached cooling chamber
FR1072554A (en) * 1952-12-22 1954-09-14 Chaufferie Et Fumisterie Ind Improvements in rotary hearth furnaces, in particular billet reheating furnaces
DE1201380B (en) * 1958-05-07 1965-09-23 Lee Wilson Method and device for the heat treatment of loosened metal tape reels
FR1218675A (en) * 1958-12-30 1960-05-12 Salem Brosius S A Holding Rotary deck ovens
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Non-Patent Citations (1)

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Title
See references of WO8602103A1 *

Also Published As

Publication number Publication date
DE3435376A1 (en) 1986-05-15
WO1986002103A1 (en) 1986-04-10
JPS62500310A (en) 1987-02-05
DE3435376C2 (en) 1996-09-12
JPH08967B2 (en) 1996-01-10

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