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
  • C21D1/34—Methods of heating
  • C21D1/40—Direct resistance heating
• • 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
  • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
• • 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
  • C21D2221/00—Treating localised areas of an article
• • 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
  • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
  • C21D9/54—Furnaces for treating strips or wire
  • C21D9/56—Continuous furnaces for strip or wire
  • C21D9/62—Continuous furnaces for strip or wire with direct resistance heating

Definitions

• the present invention relates to a method and a device for partial heating of metal sheets for the purpose of establishing zones, or lines, permanently lowering the yield point of the sheets. At those zones or lines there will later on be carried out a plastic deformation subsequently to the sheets having, by hardening or cold- orking, been given an increased yield point, generally causing deteriorated ductility.
• the object of the present invention is to provide a method and a device for partial heating in the context mentioned above, and to eliminate the disadvantages enumerated here.
• the features characterizing the invention are set out in the subsequent claims .
• the invention there have now become available a method and a device which in an excellent manner satisfies its purpose.
• the method can be carried out con-veniently and the device can be manufactured at low cost .
• a resistance heating device provided with at least one electrode of carbon, graphite or a non- metallic material having similar properties and ex-hibiting low friction values when the electrode, or the elec-trodes when they are two in number, mounted one on each side of the sheet, and are displaced while pressed against it.
• the use of this method and of this device results in a heating pattern having great advantages in comparison with the previously known methods .
• the electrode points When, in the case where two electrodes are used, the current feed is initiated, the electrode points will get very hot, meaning that the sheet is heated from both sides, right out to the outermost portion, i.e. not mainly in the center, and simultaneously a resistance heating is generated due to the current passage. Thanks to the invention a very quick heating occurs and the friction between the metal sheets and the electrodes is very low. Moreover, the extension of the heated zone is precise because it is possible to complete the process very quickly and because it can be directed. There is also a possibility to influence the heating process by variation of the electrode pressure, the feeding speed and the current characteristic resulting in different balances in response to the re- sistance Cheating and to the heating emanating the hot electrodes .
• the invention is below described more in detail with reference to a preferred embodiment .
• the field of application of the invention is partial heating of metal sheets in order to establish zones which are to be plastically deformed subsequently to the sheets having, by hardening or cold working, been given a higher yield point, and hence generally a lower ductility.
• Its structure could be such that it comprises two opposite electrodes, facing each other at a variable distance between them determined by the thickness of the metal sheet which is to be used.
• the electrodes consist of carbon, graphite or of a non-metallic material with similar pro- perties. They have a low friction value when pressed against the metal sheet from opposite sides thereof. The electrodes and the sheet can be moved relatively each other during the heating process .
• the electrode diameter can vary from a few mms and upwards and the electrode pressure does not have to be higher than within the order of magnitude of 1,5 - 15 N/mm 2 . Also, the electrode diameter could be different for those above and those below the sheet, to create an unsym- metric heating.
• the current source could be constituted by a simple welding transformer. When two electrodes are used they may be mounted one on each side of the sheet making it possible for the current through the sheet to flow from the one electrode to the other. When feed current is switched on the electrode tips turn very hot, even glowing, and they heat the sheet from both sides. The current passage yields a symmetric heating of the sheet .
• the heating takes place from the one side of the sheet, where the current flows from that electrode to the sheet, which is connected to ground or in contact with an underlying, grounded metal plate, this results in a more unilateral heating, i.e. a non- symmetrical heating in the thickness direction, than what is the case in the embodiment utilizing two electrodes.

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)
• Control Of Resistance Heating (AREA)
• Heat Treatment Of Strip Materials And Filament Materials (AREA)
• Resistance Heating (AREA)

Applications Claiming Priority (3)

Publications (2)

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ID=20282260

Family Applications (1)

Country Status (6)

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Family Cites Families (6)

• 2000
  • 2000-12-15 SE SE0004665A patent/SE520369C2/sv not_active IP Right Cessation
• 2001
  • 2001-11-29 AT AT01271454T patent/ATE335858T1/de not_active IP Right Cessation
  • 2001-11-29 EP EP01271454A patent/EP1341936B1/fr not_active Expired - Lifetime
  • 2001-11-29 DE DE60122206T patent/DE60122206D1/de not_active Expired - Lifetime
  • 2001-11-29 AU AU2002218615A patent/AU2002218615A1/en not_active Abandoned
  • 2001-11-29 WO PCT/SE2001/002649 patent/WO2002050316A1/fr active IP Right Grant

Non-Patent Citations (1)

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