WO2005123970A1 - Procédé et dispositif pour le durcissement de pièces métalliques - Google Patents

Procédé et dispositif pour le durcissement de pièces métalliques Download PDF

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Publication number
WO2005123970A1
WO2005123970A1 PCT/IN2004/000168 IN2004000168W WO2005123970A1 WO 2005123970 A1 WO2005123970 A1 WO 2005123970A1 IN 2004000168 W IN2004000168 W IN 2004000168W WO 2005123970 A1 WO2005123970 A1 WO 2005123970A1
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WO
WIPO (PCT)
Prior art keywords
gas
chamber
quenching
recited
objects
Prior art date
Application number
PCT/IN2004/000168
Other languages
English (en)
Inventor
Narasimhan Gopinath
Original Assignee
Narasimhan Gopinath
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 Narasimhan Gopinath filed Critical Narasimhan Gopinath
Priority to PCT/IN2004/000168 priority Critical patent/WO2005123970A1/fr
Publication of WO2005123970A1 publication Critical patent/WO2005123970A1/fr

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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
    • C21D1/62—Quenching 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
    • C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
    • C21D1/613—Gases; Liquefied or solidified normally gaseous material
    • 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
    • C21D9/0062—Heat-treating apparatus with a cooling or quenching zone

Definitions

  • the present invention pertains to a method of hardening sintered objects by passing pressurised gases over them.
  • quenching a metallic object i.e., rapidly chilling the object from an elevated temperature in the austenitic range to a lower temperature usually to the bainite or martensitic range
  • quenching has been carried out using liquids such as water, oil or brine.
  • gas quenching techniques have been developed, the advantages being cleanliness, non-toxicity and elimination of residues after quenching.
  • Vacuum and batch furnaces with special atmospheres are available with pressurised gas quenching systems and a number of patents have been issued.
  • Sintering has traditionally been done in continuous as well as batch furnaces with pressed compacts of powder being sintered in various types of continuous furnaces, predominantly wire mesh belt furnaces and injection moulded powder compacts being processed predominantly in batch type vacuum or atmosphere furnaces.
  • the act of sintering involves firstly the removal of binders from the compacts and heating the compacts at a suitable temperature in an atmosphere which is neutral, reducing or vacuum, then cooling the now sintered parts in the same atmosphere before removing the sintered parts from the furnace and exposing them to air.
  • Heat treatment or hardening & tempering is traditionally done as a separate operation after the act of sintering.
  • sinter hardening was developed to eliminate the separate heat treatment operation and several devices, generally fitted to continuous mesh belt furnaces were developed essentially to increase the rate of cooling of the parts once they have been sintered so as to obtain an improvement in physical properties.
  • sinter hardening devices involve the suction of the sintering furnace atmosphere by a blower or fan through a heat exchanger and passing the cooled gas over the parts as they emerge from the sintering furnace.
  • Such systems work at atmospheric pressure or slightly above, at any rate at pressures below a maximum of 300 mm water column.
  • the heat extraction capability of such devices is significantly slower than what is obtained in conventional heat treatment and consequently the hardenability of parts to be successfully processed in this manner have to be improved by alloying the powder with elements such as M ⁇ lybdeum which increases the cost of the parts.
  • the present patent application describes the development of a device which uses recirculated gas variably between atmospheric pressure upto 20 bar which is directed on the sintered parts as they emerge from a continuous sintering furnace, in one or more layers (on trays).
  • the gas is recirculated by a fan across a heat exchanger which removes the heat from the quenching system.
  • the process of the invention can be used in conjunction with furnaces like a continuous roller hearth furnace, walking beam furnace or pusher furnace. It can also be used as a retrofit to the furnaces stated above without expensive modifications. Through exhaustive theoretical calculations and experimental analyses, the equipment has been designed to achieve cooling rates that will increase the hardness and other physical properties of sintered parts which need not use as much alloying elements to increase hardenability, thus reducing the cost of manufacturing the part.
  • Figurel A is an elevation view one type of equipment of the present invention.
  • Figurel B is a side view of the said equipment of the present invention.
  • Figure 2 is a sectional top view of the said equipment shown in figure 1A showing the guide vanes around the fan.
  • Figure 3 is an elevation view of the vestibule chamber showing the openings for issuing the gas.
  • the present invention provides a method and apparatus for metal processing.
  • a sintered part that has been subjected to high temperature processing in a continuous furnace is cooled in a pressurised gas quenching chamber in which pressurised gas at high velocity is circulated uniformly on the surface of the component to obtain improved metallurgical properties.
  • Another aspect of the invention deals with cooling a metallic object heated in a continuous heat treatment furnace in a pressurised gas-quenching chamber to obtain higher hardness.
  • the method of the present invention is applied for 'sinter hardening' of metal parts that have been subjected to sintering in a continuous furnace.
  • the method of the present invention is applied for hardening of metal parts that have been heated in a continuous hardening (heat treatment) furnace.
  • FIG1A and FIG1B an elevation view and side view respectively of the apparatus used for pressurized gas quenching in a continuous sintering furnace.
  • the equipment mainly consists of a vestibule chamber 110, the dimensions of which are such that it can accommodate a tray coming out of the furnace.
  • the tray can be transported in the vestibule chamber by a pusher mechanism or roller mechanism or chain drive.
  • the vestibule chamber has a sealed door 109 towards the entry end and is capable of withstanding upto 20 bar pressure. The door is sealed suitably to avoid the gas in the quenching chamber from entering the furnace when the quenching apparatus is being pressurized.
  • the door is an automatic door, which operates at equal intervals to let the tray inside the vestibule chamber.
  • a shell 115 encloses the entire assembly and is capable of withstanding a pressure of 20 bar.
  • the outer shell 115 and inner plate 118 form a guide way 103 for the gas circulated by the fan to issue on the tray through the opening 117 on either side of the vestibule chamber.
  • Fig 3 shows the vestibule chamber with opening 117 on one side. The opening is present on the other side of the vestibule chamber also, opposite to the first opening and of the same size. Apart from the openings on either side of the vestibule chamber, there is an opening on the top of the vestibule chamber also, located centrally.
  • the guide way 103 has its exit merging with the opening 117 of the vestibule chamber.
  • a heat exchanger 104 is placed directly on top of the opening on top of the vestibule chamber.
  • a duct 119 which has an inlet dimension to match that of the opening in the vestibule chamber, and an exit dimension to match that of the cross section of the heat exchanger, is placed between the heat exchanger and the vestibule.
  • the heat exchanger 104 is a counter flow heat exchanger and has provisions for water entry 112 and water exit 111.
  • a duct 106 is placed on top of the heat exchanger and has entry dimensions that match the cross section of the heat exchanger and exit dimensions that match the inner diameter of the fan 102 placed directly on top of duct 106.
  • the fan is rotated by a motor 100, which is also enclosed inside a shell 107.
  • a suction line 114 is provided for the suction of gases prior to pressurising the chamber.
  • the entire apparatus is pressurized through a pressurising line 113 which has suitable means to pressurise the chamber to the desired pressure.
  • Fig 2 shows the guide vanes 116 located on either side of the fan for the uniform flow of gases.
  • a gas tight door 108 is present at the exit of the vestibule, which operates sequentially to deliver the tray periodically.
  • the shell 115 can be designed in such a way that gas impinges on all sides of the tray through nozzles/openings, to quench the sintered parts suitably.
  • the gas quenching chamber is capable of withstanding a temperature of 900°C.
  • the door 109 closes and the chamber is evacuated by suction line 114.
  • the chamber is then pressurized by the quenching gas which would be a gas that prevents the oxidation of or carbon loss from the objects being quenched and would generally but not necessarily be similar to the furnace atmosphere gas being typically Endogas and/or nitrogen or either inert gases with or without addition of other gases including hydrogen and helium through the pressurizing line 113.
  • the fan is switched on and as the fan 102 rotates, it sucks the gas through the heat exchanger 104 where the hot gases get cooled and delivers the same through the guide way 103.
  • the chamber is depressurized and the exit door 108 opens. The tray is pushed out of the vestibule chamber. And the exit door 108 closes.
  • the vestibule chamber can have either a roller mechanism or pusher mechanism or a chain drive for transportation of the objects from the sintering section or the post sintering carburising or slow cooling section to the quench chamber.
  • the quenching gas can be a gas which prevents the oxidation of or carbon loss from the objects being quenched and would generally but not necessarily be similar to the furnace atmosphere gas being typically Endogas and/or nitrogen or either inert gases with or without addition of other gases including hydrogen and helium through the pressurizing line 113.
  • the pressure required for a particular part and property will vary depending on the gas compositions selected.
  • the pressurised gas can be stored and reused for subsequent quenching.
  • the gas used for quenching can be reused in the sintering section of the furnace. 5.
  • the gas used for quenching can be reused in the dewaxing section of the furnace for the purpose of evacuating vapourised binder fumes.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Powder Metallurgy (AREA)
  • Tunnel Furnaces (AREA)

Abstract

La présente invention a trait à un procédé pour la trempe d'objets frittés au sein d'un four de frittage en continu comprenant la décharge d'une pluralité de flux de gaz sous pression en provenance de conduits menant vers les objets, de sorte que les flux de gaz produisent un impact substantiel et uniforme à la surface des objets et le recyclage dudit flux de gaz sous pression à travers un échangeur de chaleur.
PCT/IN2004/000168 2004-06-15 2004-06-15 Procédé et dispositif pour le durcissement de pièces métalliques WO2005123970A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/IN2004/000168 WO2005123970A1 (fr) 2004-06-15 2004-06-15 Procédé et dispositif pour le durcissement de pièces métalliques

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/IN2004/000168 WO2005123970A1 (fr) 2004-06-15 2004-06-15 Procédé et dispositif pour le durcissement de pièces métalliques

Publications (1)

Publication Number Publication Date
WO2005123970A1 true WO2005123970A1 (fr) 2005-12-29

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Country Status (1)

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WO (1) WO2005123970A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008041117A1 (fr) * 2006-10-06 2008-04-10 Shap Solar Heat And Power S.P.A. Ensemble de trempe à haute vitesse pour produits métalliques
WO2010081587A1 (fr) * 2009-01-14 2010-07-22 Robert Bosch Gmbh Dispositif et procédé de trempe
CN112556426A (zh) * 2020-12-15 2021-03-26 江西科技学院 一种具有气相淬火功能的烧结炉及其淬火工艺

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59159926A (ja) * 1983-02-28 1984-09-10 Shimadzu Corp 熱処理装置
US4867808A (en) * 1987-10-28 1989-09-19 Degussa Aktiengesellschaft Heat treating a metallic workpiece by quenching under cooling gas under above atmospheric pressure and specified circulation rate
EP0796920A1 (fr) * 1996-02-21 1997-09-24 Ipsen International GmbH Dispositif de trempe de pièces métalliques
DE19623559A1 (de) * 1996-06-13 1997-12-18 Werner Hermann Wera Werke Vorrichtung und Verfahren zum Härten von metallischen Werkstücken
EP1154024A1 (fr) * 2000-04-14 2001-11-14 Ipsen International GmbH Procédé et dispositif pour le traitement thermique de pièces métalliques

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59159926A (ja) * 1983-02-28 1984-09-10 Shimadzu Corp 熱処理装置
US4867808A (en) * 1987-10-28 1989-09-19 Degussa Aktiengesellschaft Heat treating a metallic workpiece by quenching under cooling gas under above atmospheric pressure and specified circulation rate
US4867808B1 (fr) * 1987-10-28 1994-02-22 Leybold Durferrit Gmbh
EP0796920A1 (fr) * 1996-02-21 1997-09-24 Ipsen International GmbH Dispositif de trempe de pièces métalliques
DE19623559A1 (de) * 1996-06-13 1997-12-18 Werner Hermann Wera Werke Vorrichtung und Verfahren zum Härten von metallischen Werkstücken
EP1154024A1 (fr) * 2000-04-14 2001-11-14 Ipsen International GmbH Procédé et dispositif pour le traitement thermique de pièces métalliques

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008041117A1 (fr) * 2006-10-06 2008-04-10 Shap Solar Heat And Power S.P.A. Ensemble de trempe à haute vitesse pour produits métalliques
WO2010081587A1 (fr) * 2009-01-14 2010-07-22 Robert Bosch Gmbh Dispositif et procédé de trempe
CN112556426A (zh) * 2020-12-15 2021-03-26 江西科技学院 一种具有气相淬火功能的烧结炉及其淬火工艺
CN112556426B (zh) * 2020-12-15 2022-08-23 江西科技学院 一种具有气相淬火功能的烧结炉及其淬火工艺

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