EP2345747A1 - Procédé et dispositif pour la reduction du risque d'incendie et la suppression de fumée lors de la trempe en bain d'huile - Google Patents

Procédé et dispositif pour la reduction du risque d'incendie et la suppression de fumée lors de la trempe en bain d'huile Download PDF

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Publication number
EP2345747A1
EP2345747A1 EP10000364A EP10000364A EP2345747A1 EP 2345747 A1 EP2345747 A1 EP 2345747A1 EP 10000364 A EP10000364 A EP 10000364A EP 10000364 A EP10000364 A EP 10000364A EP 2345747 A1 EP2345747 A1 EP 2345747A1
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EP
European Patent Office
Prior art keywords
bath
inert gas
quenching
oil
gas flow
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Withdrawn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
EP10000364A
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German (de)
English (en)
Inventor
Tero Ristolainen
Reijo Luukkanen
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.)
Linde GmbH
Original Assignee
Linde GmbH
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 Linde GmbH filed Critical Linde GmbH
Priority to EP10000364A priority Critical patent/EP2345747A1/fr
Publication of EP2345747A1 publication Critical patent/EP2345747A1/fr
Withdrawn legal-status Critical Current

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    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING 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
    • C21D1/00General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/62Quenching devices
    • C21D1/63Quenching devices for bath quenching
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING 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
    • C21D1/00General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING 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
    • C21D9/00Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0062Heat-treating apparatus with a cooling or quenching zone

Definitions

  • the invention relates to a method for cooling a metal part in a bath of a quenching medium wherein said metal part is submerged into said bath. Further the invention relates to a device for cooling a metal part comprising a tank with a bath of a quenching medium.
  • the quenching is often practiced using oil as quenching medium.
  • the hot metal part is submerged into an oil bath and rapidly cooled down.
  • oil When submerging the metal part into the oil bath there is a considerable risk that oil will flame up. Oil boiling and the risk for fire might also occur if the viscosity of the oil increases to a point where it overheats or if there is a loss of thermal stability in the oil and low flash point fractions are produced.
  • This object is achieved by a method for cooling a metal part in a bath of a quenching medium wherein said metal part is submerged into said bath, and which is characterized in that an inert gas is blown to the surface of said bath.
  • the inventive device for cooling a metal part comprising a tank with a bath of a quenching medium, is characterized in that an inert gas supply and an inert gas supply line is provided wherein said inert gas supply line comprises at least one opening for supplying inert gas to said tank.
  • the bath of the quenching medium is blanketed with an inert gas.
  • the inert gas is blown to the surface of the bath such that an inert gas layer is built up on or above the surface of the quenching medium.
  • the quenching medium is a liquid.
  • the quenching medium is an oil or comprises an oil, for example a hydrocarbon based oil or a mineral oil, or a non-aqueous fluid, especially a synthetic non-aqueous fluid.
  • nitrogen is used as inert gas.
  • Nitrogen does not react with the metal part which is cooled and nitrogen does also not effect the quenching medium.
  • the oil composition will not be effected by the nitrogen.
  • the temperature of the quenching oil raises due to the hot metal submerged into the oil the quenching oil is degraded by the oxygen present in the air. This degradation does not occur when the bath is covered by a layer of nitrogen gas according to the invention.
  • the inert gas will supersede the air normally covering the bath of quenching medium.
  • the oxygen concentration directly over the bath of quenching medium will be reduced. This will reduce the risk of fire hazards and decrease fumes at the operation site, for example in a production hall.
  • the inert gas is blown to the surface of the quenching bath in an essentially horizontal direction.
  • the atmosphere e.g. the air
  • the atmosphere above the quenching bath will be blown away by the inert gas.
  • the time for exchange of the atmosphere above the bath, from air to inert gas, is considerably reduced.
  • the inert gas can be continuously provided to the bath surface. Preferably the same flow of inert gas is applied to the quenching bath all the times. In that case the inert gas flow is preferably set to a constant value such that there is always a satisfactory inert atmosphere above the quenching bath in order to prevent ignition of the quenching medium and/or to avoid degradation of the quenching medium by a too high concentration of oxygen.
  • the flow of inert gas is changed with time.
  • the inert gas flow is changed from a lower flow rate to a higher flow rate and/or vice versa.
  • the inert gas flow can be changed several times and can vary between several flow rates.
  • the inert gas flow is preferably controlled depending on the time when the metal object is submerged into the quenching bath. Other parameters which can be used to control the inert gas flow are the oxygen concentration above the quenching bath and/or on another parameter of the quenching process.
  • the inert gas flow can be changed between zero flow and maximum flow.
  • the inert gas is controlled such that there is always a minimum inert gas flow which is temporarily increased.
  • the minimum inert gas flow is preferably set to such a value that the oxygen concentration above the quenching bath is low enough to avoid negative interactions of the oxygen with the quenching medium.
  • the flow rate of the minimum inert gas flow depends on the surface area of the quenching bath and/or on the open volume above quenching bath.
  • the gas flow is increased depending on pre-defined parameters, such as oxygen concentration above the quenching bath, temperature of the quenching bath, the temperature, size and / or heat capacity of the metal object to be cooled, or the time the metal object is lowered into the quenching bath.
  • the change of the inert gas flow can be stepwise or continuously.
  • the most critical moment is when the hot metal object is lowered into the quenching medium. Therefore, it has been found advantageous to increase the inert gas flow for a defined time period before the hot metal object is lowered into the bath. It is further advantageous to increase the inert gas flow during the time when the metal object is brought into contact with the quenching medium and/or for a defined period of time after the metal object has been submerged into the bath.
  • the inert gas flow is increased for a few minutes, preferably for 1 to 10 minutes before the hot metal is submerged into the quenching medium.
  • the inert gas layer is increased and the oxygen concentration at the surface of the quenching bath decreased and consequently the risk of fire is prevented or at least considerably reduced.
  • an increased inert gas flow for a certain period of time after the metal object has been lowered into the quenching oil. This period of time is preferably between 1 and 10 minutes.
  • the inert gas flow is increased to at least 500 Nm 3 /h, more preferred to at least 1000 Nm 3 /h, even more preferred to at least 1200 nm 3 /h.
  • the inert gas flow is again reduced to a flow rate below 300 Nm 3 /h.
  • Hot metal parts shall be cooled in a bath of quenching oil. For safety reasons, during idling the oil bath is covered with a lid which is opened or removed before quenching. The hot metal parts are lifted with a crane and then lowered into the tank with the oil bath.
  • the whole volumen of the tank with the oil bath is around 20 m 3 .
  • the open space between the lid and the oil depends on the level of the oil and is normally between 5 and 10 m 3 .
  • the inert gas flow preferably nitrogen gas, is set to a minimum flow rate of 5 to 10 Nm 3 /h which is always always blown onto or along the surface of the bath of quenching oil. This minimum inert gas flow guarantees that the atmosphere above the oil bath remains inert and that the quality of the quenching oil is good. A few minutes, preferably 5 to 10 minutes, before the metal part which shall be cooled is lowered into the oil bath the inert gas flow rate is increased.
  • the increase of flow rate could be for example to a level of about 300 m 3 /h to decrease the oxygen content in a layer above the oil bath.
  • the increased flow rate could be held for a certain period of time, for example 10 minutes, or until the oxygen content at a certain distance above the oil bath goes below a pre-defined value.
  • One to three minutes before the metal part is lowered into the oil bath the inert gas flow is increased to roughly 1200 m 3 /h. This high inert gas flow rate will last for 3 to 4 minutes. Then the inert gas flow is lowered back to 300m 3 /h for a couple of minutes, for example 5 to 15 minutes. Finally, the inert gas flow is reduced to the minimum flow rate of 5 to 10 m 3 /h.
  • the inert gas flow is automatically controlled.
  • the inert gas flow is set to a minimum gas flow which is, according to a pre-defined schedule, increased at certain times, at certain conditions and/or when a particular variable, for example a monitored variable, meets a pre-defined value.
  • the degradation or oxidation of an oil used as quenching medium can be detected by infrared spectroscopy. It could also be measured by several other methods, including precipitation number, total acid number, sludge content and viscosity.
  • the invention also works with a zero minimum inert gas flow.
  • the inert gas flow is started before the metal to be cooled is lowered into the bath.
  • the flow rate of inert gas and / or the time period between starting of the inert gas flow and submerging the metal part into the quenching bath is in that case increased compared to a process wherein a non-zero minimum inert gas flow is used.
  • the inventive method is in particular useful for quenching objects made of iron, steel, copper, aluminium or other metals.
  • the inventive device comprises a tank with a bath of a quenching medium, an inert gas supply and an inert gas supply line wherein the inert gas supply line comprises at least one opening for supplying inert gas to the bath of a quenching medium.
  • the inventive device comprises an inert gas supply line which comprises a ring line with several openings for providing inert gas.
  • the ring line is preferably arranged along the circumference of the tank of quenching medium.
  • the ring line will be a circular line with several gas outlet openings which are preferably directed in a radial direction to the center of the ring line such that any gas provided through the gas outlet openings flows in a more or less horizontal direction.
  • the gas outlet openings are preferably in the form of bores or slots. It is also possible to provide only one slot which extends along the whole inner circumference of the ring line.
  • FIG. 1 schematically shows an inventive system for supplying inert gas to a quenching bath 1.
  • a tank 1 is filled with oil which is used as a quenching medium to rapidly cool down hot metal objects.
  • the hot metal objects are submerged into the quenching bath 1 whereby they are shock-cooled by direct heat exchange with the quenching oil.
  • an inert gas is supplied to the surface of the quenching bath 1.
  • Nitrogen is withdrawn from a nitrogen tank 2 via a nitrogen supply line 3.
  • Nitrogen supply line 3 splits up into two parallel lines 4a, 4b.
  • Each line 4a, 4b comprises a flow control unit 5a, 5b and a shut-off valve 6a, 6b arranged in series with the flow control unit 5a, 5b, respectively.
  • Each flow control unit 5a, 5b comprises two flow meters 7a, 8a, 7b, 8b also arranged in parallel.
  • Control unit 9 further comprises a timer control such that shut-off valves 6a, 6b can be controlled depending on the time and on the measured parameter.
  • the nitrogen gas flow can be controlled by opening or closing one or both of the shut-off valves 6a, 6b. It is further possible not only to control the shut-off valves 6a, 6b but also the flow control units 5a, 5b or even each of the flow meters 7a, 8a, 7b, 8b. This will allow for a more continuous variation of the nitrogen gas flow to the quenching bath 1 rather than a stepwise change of the nitrogen gas flow.
  • Figure 4 shows the correlation between the nitrogen gas flow for blanketing the bath of quenching oil 1 and time. Independent of time there is always a constant flow F1 of nitrogen gas in order to create and maintain a nitrogen gas layer above the quenching oil 1. This is achieved by leaving shut-off valve 6a open and closing shut-off valve 6b. Thus, a gas flow F1 is continuously supplied to the sprinkler system.
  • nitrogen gas flow F2 is more than double of nitrogen gas flow F1.
  • the magnitude of the gas flows F1 and F2 depends on the design and settings of flow control units 5a and 5b.
  • the magnitudes of nitrogen gas flows F1 and F2 will be set according to the requirements of the process.
  • any other ratio of F1 to F2 is also possible.
  • it is advantageous to use identical flow meters 7a, 8a, 7b, 8b. In that case by opening shut-off valve 6b the nitrogen gas flow will be doubled, that is F2 2 * F1.
  • the nitrogen gas flow is maintained at flow rate F2 until time t3.
  • the metal object has been sufficiently cooled down and oil splashs will no more occur. Therefore, there is no more risk of fire and the main task of the inventive nitrogen gas flow is to protect the quenching oil from oxygen in order to avoid degrading of the oil. So the nitrogen gas flow can be lowered to F1 again.
  • Figure 4 shows a stepwise control of the nitrogen gas flow to the quenching bath 1.
  • shut-off valves 6a, 6b depending on the time of contacting the hot metal object with the oil bath 1.
  • the nitrogen gas flow is not stepwise changed but continuously.
  • Flow meters 7a, 8a, 7b, 8b could be controlled by magnetic valves which are controlled by control unit 9. Further control parameters beside the time control already described could be the oxygen content above the oil bath 1 or the quality of the quenching oil.
  • Figures 2 and 3 show the quenching bath 1 in more detail.
  • Figure 2 shows a vertical cross section of the quenching bath 1
  • figure 3 shows a top view of the quenching bath 1.
  • the quenching bath 1 comprises an oil drum 14 which is filled with a quenching oil 11 up to a height 12. Inside the oil drum 14 there is a stainless steel annular tube or ring torus 13 which is connected to nitrogen supply line 3. The annular tube 13 is arranged near the top of the oil drum 14 at a distance between 5 and 300 mm from the top of the oil drum 14. The annular tube 13 abuts with its outer circumference on the inner wall of the oil drum 14.
  • the annular tube 13 At its inner surface - opposite to the inner wall of the oil drum 14 - the annular tube 13 comprises a number of openings 15 in the form of horizontal slots. Gaseous nitrogen supplied via nitrogen-supply line 3 to the annular tube 13 will flow out of annular tube 13 through the slots 15. The nitrogen gas flows out in an essentially horizontal direction directed to the center of the oil drum 14 (see figure 3 ). Thus the nitrogen gas will create an inert gas blanket over the oil bath 11.

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  • 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)
  • Heat Treatments In General, Especially Conveying And Cooling (AREA)
  • Heat Treatment Of Articles (AREA)
EP10000364A 2010-01-15 2010-01-15 Procédé et dispositif pour la reduction du risque d'incendie et la suppression de fumée lors de la trempe en bain d'huile Withdrawn EP2345747A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP10000364A EP2345747A1 (fr) 2010-01-15 2010-01-15 Procédé et dispositif pour la reduction du risque d'incendie et la suppression de fumée lors de la trempe en bain d'huile

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Application Number Priority Date Filing Date Title
EP10000364A EP2345747A1 (fr) 2010-01-15 2010-01-15 Procédé et dispositif pour la reduction du risque d'incendie et la suppression de fumée lors de la trempe en bain d'huile

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EP2345747A1 true EP2345747A1 (fr) 2011-07-20

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EP10000364A Withdrawn EP2345747A1 (fr) 2010-01-15 2010-01-15 Procédé et dispositif pour la reduction du risque d'incendie et la suppression de fumée lors de la trempe en bain d'huile

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB987338A (en) * 1963-04-03 1965-03-24 Gibbons Brothers Ltd New or improved transfer devices for articles
FR1536983A (fr) * 1967-05-23 1968-08-23 Uk Nii Metallov Dispositif pour la trempe à l'huile de laminés, notamment des rails
DE3538754C1 (de) * 1985-10-31 1987-01-29 Aichelin Gmbh Verfahren und Vorrichtung zum Abschrecken von Gluehgut
JPH07331326A (ja) * 1994-06-10 1995-12-19 Fuji Denshi Kogyo Kk 無酸化焼入方法及び無酸化焼入装置
JP2005232548A (ja) * 2004-02-20 2005-09-02 Daido Steel Co Ltd 油焼入装置
JP2008208420A (ja) * 2007-02-26 2008-09-11 Dowa Thermotech Kk 熱処理方法及び熱処理設備

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB987338A (en) * 1963-04-03 1965-03-24 Gibbons Brothers Ltd New or improved transfer devices for articles
FR1536983A (fr) * 1967-05-23 1968-08-23 Uk Nii Metallov Dispositif pour la trempe à l'huile de laminés, notamment des rails
DE3538754C1 (de) * 1985-10-31 1987-01-29 Aichelin Gmbh Verfahren und Vorrichtung zum Abschrecken von Gluehgut
JPH07331326A (ja) * 1994-06-10 1995-12-19 Fuji Denshi Kogyo Kk 無酸化焼入方法及び無酸化焼入装置
JP2005232548A (ja) * 2004-02-20 2005-09-02 Daido Steel Co Ltd 油焼入装置
JP2008208420A (ja) * 2007-02-26 2008-09-11 Dowa Thermotech Kk 熱処理方法及び熱処理設備

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