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
  • C21D1/673—Quenching devices for die quenching
• • 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

Definitions

• the invention relates to methods for the heat treatment of metallic material (e.g. easily distorted steel parts such as sheet metal, round blanks and the like) by means of a roller furnace and presses (so-called quenching) which interact with it, in which the material is subjected to a predetermined Bring temperature and is cooled between press parts with a predetermined cooling rate.
• metallic material e.g. easily distorted steel parts such as sheet metal, round blanks and the like
• the blanks For the thermal treatment of steels, in particular also for hardening, it has hitherto been customary for the blanks to be brought to the austenitizing temperature.
• several salt baths are used, which are set to a fixed temperature and which are passed through by a blank in succession.
• the blank which has been brought to the desired temperature is quenched, for which purpose a quenching medium is required, namely oil as well as air, water and salt baths.
• Quetten metal parts, e.g. B. cylinder blocks when it comes to hardening saw blade blanks. These metal parts press on the blank from both sides during the cooling process.
• the heat treatment process described above is not just about the hardness of a blank, it should also be aimed at a uniform structure that is distributed as evenly as possible over the cross section, so-called decarburization zones in the blanks being undesirable because they are used for large-area and thin blanks cause the blank to warp later.
• the aim is to provide a high temperature range that is significantly higher than at those temperatures at which previous heat treatment devices operate.
• a high temperature range should be avoided in connection with the heat treatment of steels, since such a temperature entails, among other things, changes in the carbon content, ignition and warping of the blanks.
• it has been recognized by the invention that such a high temperature range is not only harmless in view of the problems listed above, but also leads to considerable advantages, namely in that even such steels can now be processed and in particular hardened that have so far only led to the desired properties when quenching under oil.
• the area of particularly high temperatures is run through at a high speed, this speed being determined in a manner adapted to the other conditions, in particular the shape and shape of the blanks.
• the level of the temperature depends on the materials selected, it also depends on whether the object to be hardened has a smaller thickness in the case of large dimensions or whether it is more or less compact blanks. The same applies to the temperature.
• the aforementioned process parameters can be determined by simple tests so that optimal values are achieved.
• the blanks are arranged between press parts during cooling, the pressure of the two press parts on one another or is controlled in a time-dependent manner on the blank.
• a phase of high pressure is followed by a reduction in the pressure, so that only the dead weight of the upper press acts on the blank, and it is precisely this reduction in pressure that has led to the blanks being able to be treated without distortion even in the case of unfavorable dimensioning conditions.
• an essential finding of the present invention is that the properties of the machined blank depend on the temperature at which the blank has passed the rapid draw-off zone and the speed at which.
• At the outlet of the roller furnace there is at least one quench unit, preferably two, which are alternately fed with the blanks which are at the appropriate temperature. In this way it is possible to have sufficiently long cooling processes to perform and still work adapted to the throughput of the roller kiln.
• the method according to the invention can also be applied to blanks made from such steels which have hitherto also been able to be hardened in air. In this context, a significantly lower energy expenditure is shown for the pairs according to the invention.
• the process can be applied to blanks with a thickness of up to 20 mm and shows in this context its superiority to known processes, especially in the required energy consumption.
• roller ovens which can be used according to the invention can be adjusted to the desired conditions; roller ovens are known which master the temperature range from 850 to 1350 ° C.
• the basis for the partial hardening of flat products in this system is the requirement that a partial area be fully hardened, another area unhardened or only tempered.
• the furnace area in the area of the austenitizing zone is equipped with a cover for the roller conveyor above and below.
• the material to be hardened now passes through an area in which the material takes on the austenitizing temperature, and on the other side a shielded area in which the material is warmed a few hundred degrees Kelvin colder at the end of the austenitizing zone.
• the product is then removed very quickly and placed under the hardening press.
• the subsequent rapid cooling ensures that the material has full hardness in the fully hardened, uncovered area and shows significantly lower hardness values in the covered area. This is particularly necessary for knives that have a cutting part and a clamping part.
• the cutting part should be very hard, while the clamping part should remain soft.
• the structure also corresponds to a tough and good structure.
• the core idea is the hardening and simultaneous straightening or the distortion-free hardening of the blanks, as well as the return from hardening of round materials by introducing them into a mold to the known hardening of flat products.
• the invention relates in particular to the hardening of steel workpieces and preferably to the distortion-free hardening of flat products of whatever steel they are made of.
• the temperature in the roller furnace is controlled in such a way that the temperature of the material decreases only insignificantly in the rapid draw-off area and the material reaches the hardening presses above the austenitizing temperature.

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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 Treatment Of Articles (AREA)
• Heat Treatments In General, Especially Conveying And Cooling (AREA)
• Heat Treatment Of Strip Materials And Filament Materials (AREA)

Applications Claiming Priority (2)

Publications (2)

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Country Status (3)

Cited By (4)

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Citations (6)

• 1993
  • 1993-05-19 DE DE4316795A patent/DE4316795A1/de not_active Withdrawn
• 1994
  • 1994-05-18 DE DE59407034T patent/DE59407034D1/de not_active Expired - Lifetime
  • 1994-05-18 EP EP94107705A patent/EP0632137B1/fr not_active Expired - Lifetime
  • 1994-05-18 AT AT94107705T patent/ATE171984T1/de active

Patent Citations (6)

Non-Patent Citations (1)

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