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
• • 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
  • C21D1/18—Hardening; Quenching with or without subsequent tempering
  • C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
  • C21D1/20—Isothermal quenching, e.g. bainitic hardening
• • 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

Definitions

• the invention relates to a method for the heat treatment of workpieces, in which the workpieces coming from a heating system are used for cooling in a fluidized bed which is generated by at least one gas stream guided in a main flow direction, using a fluidized bed medium which has a higher thermal conductivity than the material of the workpieces to be cooled.
• Oil or salt baths in which the workpieces are immersed are often used to cool heated workpieces.
• This conventional cooling process has the advantage of evenly and precisely controllable heat extraction even on complicated workpiece surfaces.
• a serious disadvantage of using oil or salt baths for cooling heated workpieces is that the workpieces have to be cleaned regularly after being removed from the bath. This requires a considerable amount of work.
• additional safety precautions are also required. Substantial costs also result in the loss of discharge from the baths, both for oil baths and for salt baths.
• a device for the heat treatment of coiled wire or strip is also known, in which the wire ring is either immersed in an oil or salt bath or in a fluidized bed and moved in it with the aid of an oscillation system. Moving the wire ring in relation to the bath or fluid bed improves the heat exchange between the cooling medium and the workpiece exposed to the vibration movement, but in no way offsets the better effectiveness of oil or salt baths.
• the known heat treatment device can only be used in batch operation, but not in a continuous continuous cooling process.
• the invention has for its object to improve the heat treatment method of the type mentioned, which works much more environmentally friendly than the known bath treatments with less work and energy requirement, so that a more effective and, above all, more uniform heat exchange between the workpiece surfaces and the fluidized bed medium is ensured.
• This object is achieved according to the invention in that the workpieces are moved relative to the gas stream producing the fluidized bed during cooling, while individual pulse-like gas jets are introduced into the fluidized bed essentially at right angles to the main flow direction of the gas stream, and in that the fluidized bed during the treatment period of the workpieces in the Fluidized bed is maintained at a substantially constant temperature.
• the invention enables the advantages of dry heat treatment of workpieces in a fluidized bed, i.e. less work and energy requirements as well as lower environmental impact, with those of conventional heat treatments in liquid baths, i.e. to combine more uniform and intensive heat exchange between workpieces and fluidized bed medium and better controllability of the operating parameters.
• the gas flow conducted in the main flow direction usually consists of several, essentially parallel, partial flows, which together produce the fluidized bed (also called “fluidized bed” or “fluidized bed”).
• the operating parameters of the fluidized bed are selected according to the invention in such a way that cooling conditions result which even allow relatively large workpieces with a complicated surface to be treated.
• the invention ensures that a constant particle exchange also takes place on the workpiece surfaces in the so-called slipstream zones. This ensures uniform heat transfer to the fluidized bed medium, even with complexly structured workpiece surfaces.
• the fluidized bed medium preferably consists of particles of metallic or non-metallic-inorganic character; Examples of this are aluminum alloys or carbides, insofar as they have a higher thermal conductivity than the generally metallic material of the workpieces to be treated.
• the relative movement of the workpieces can be a vibration movement or long-stroke movements.
• the direction of movement is not critical, but the movements, if they are in the direction of flow of a gas stream, must be faster than the gas flow.
• the method according to the invention is particularly well suited for the intermediate stage compensation of workpieces.
• special care had to be taken when cleaning the workpieces, especially when using oil baths, as there was otherwise a risk that oil residues in the downstream holding furnace, in which the structural change takes place, would evaporate or burn and lead to uncontrollable pollutant emissions. This danger does not exist with the invention.
• the cooling conditions in the fluidized bed can be optimally adapted to the subsequent treatment in the microstructure conversion system.
• moisture preferably as water vapor
• This enables a higher heat transfer coefficient to be set. If necessary, this can shorten the residence time of the workpieces in the fluidized bed.
• the supply of moisture as water vapor ensures that no lumps form in the fluidized bed medium.
• the fluidized bed medium preferably has a constant radiation number over a wide temperature range, for example of about 600 ° C. This ensures rapid temperature compensation within the fluidized bed.
• a gas which generates the fluidized bed and has the same electrical charge sign as the particles of the fluidized bed medium. This avoids electrostatic charges, which may lead to the fluidized bed particles sticking together.
• the fluidized bed medium is regenerated during loading and unloading of the workpieces.
• the particle size of the fluidized bed medium can be kept constant and, if necessary, the particles can also be cooled. Since the regeneration takes place during loading and unloading of the fluidized bed, disturbances in the cooling process are avoided.
• the workpieces are preferably only cooled below the intended holding temperature to such an extent that the holding temperature after removal from the fluidized bed is reached by the heat flow from the core into the edge zones of the workpieces.
• the subsequent structural transformation system no heat supply to the workpieces is required. The latter was unavoidable with the well-known bath cooling system, because precise control was prohibited because of the steep temperature gradient, and therefore, due to caution, the workpieces were forced to undercool more.
• a particularly favorable use of energy results when the method according to the invention is applied to the intermediate stage tempering in that the heat emerging from the fluidized bed with the gas stream is used to heat the structural conversion system.
• the transport duration of the workpieces from the heating system to the fluidized bed is dimensioned depending on the radiation behavior of the workpieces. The stronger the radiation, the shorter the transport time should be.
• the workpieces then always enter the fluidized bed at the same temperature. The temperature differences within a batch or between individual workpiece sections can also be controlled.
• the process according to the invention can be carried out batchwise, that is to say in individual batches, or continuously, for example in continuous operation.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Crucibles And Fluidized-Bed Furnaces (AREA)
• Heat Treatments In General, Especially Conveying And Cooling (AREA)
• Heat Treatment Of Articles (AREA)
• Manufacturing Of Magnetic Record Carriers (AREA)
• Crystals, And After-Treatments Of Crystals (AREA)
• Furnace Details (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

Family

ID=6171029

Family Applications (1)

Country Status (10)

Families Citing this family (6)

Family Cites Families (15)

• 1982
  • 1982-08-17 DE DE19823230531 patent/DE3230531A1/de not_active Withdrawn
• 1983
  • 1983-07-26 DE DE8383107322T patent/DE3366291D1/de not_active Expired
  • 1983-07-26 EP EP83107322A patent/EP0103705B1/de not_active Expired
  • 1983-07-26 AT AT83107322T patent/ATE22329T1/de not_active IP Right Cessation
  • 1983-08-11 ZA ZA835890A patent/ZA835890B/xx unknown
  • 1983-08-15 JP JP58149098A patent/JPS5947322A/ja active Pending
  • 1983-08-15 DD DD83253963A patent/DD208993A5/de unknown
  • 1983-08-16 BR BR8304420A patent/BR8304420A/pt unknown
  • 1983-08-17 IN IN1013/CAL/83A patent/IN159134B/en unknown
  • 1983-08-17 KR KR1019830003840A patent/KR840005746A/ko not_active Application Discontinuation
• 1985
  • 1985-06-14 US US06/744,656 patent/US4612065A/en not_active Expired - Fee Related

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