Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
  • B22D11/0637—Accessories therefor
  • B22D11/064—Accessories therefor for supplying molten metal
  • B22D11/0642—Nozzles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
  • B22D41/50—Pouring-nozzles
  • B22D41/60—Pouring-nozzles with heating or cooling means

Definitions

• the invention relates to a method for preheating a nozzle, in particular a nozzle for supplying metal between two belts, chains or the like.
• a mold of a casting machine with a rotating wall is a part of a casting machine with a rotating wall.
• Machines have been developed for the continuous casting, in particular of ferrous and non-ferrous metals, which have a mold with constantly moving walls. These machines include machines that are cast between two rotating steel strips. These include, in particular, the well-known Hazelett band casting machines, e.g. B. according to US-PS 2,640,235.
• Machines are also known in which the casting mold is formed by a double row of mold halves, which are combined to form two endless chains. At the end of the casting, the opposing mold halves lie against each other and move in this position over a certain distance, on which they form the actual caterpillar mold. Then they separate to meet again at the end of the pouring after a short time.
• the feed nozzle for the metal is the most problematic component. This is primarily due to the fact that there are few materials that can withstand the high temperatures of the flowing metal. Graphite is one of the few materials that meet the necessary requirements. In contrast, graphite has the disadvantage of high thermal conductivity; the heat is dissipated from the molten metal so quickly that the metal tends to solidify in the nozzle.
• the parts of the feed nozzles that come into contact with the liquid metal must be made of a refractory material, the z. B. when casting aluminum from a mixture of 30% diatomaceous earth (practically pure silica in the form of microscopic cells), 30% long asbestos fibers, 20% sodium silicate (dry weight) and 20% lime (to form calcium silicate).
• Zr0 2 in particular is available as the nozzle material or also ZrSi0 4 with different Zr0 2 content, the nozzle also being able to be designed as a two-substance nozzle for reasons of cost.
• the Zr0 2 material is a stabilized, fine ceramic material with precisely adjusted porosities. Such a structure is able to absorb the Zr0 2 volume change that occurs so that disadvantageous crack formation is avoided.
• the above-described feed nozzles made of a refractory material have good thermal insulation and a small heat capacity, their main disadvantage is that the material used is characterized by low ho homogeneity with regard to the chemical composition and mechanical properties, water absorption, irreversible changes in the chemical composition when heated to working temperature and the associated further embrittlement, or low mechanical strength, and - associated with this - generally only a single use of the feed nozzle allows.
• the nozzle is subjected to considerable thermal shock when the liquid metal is poured in for the first time, and the sudden thermal stress that occurs within the nozzle body can cause it to break apart or at least tear.
• Another problem is the so-called freezing of the nozzle when metal to be cast hits the cold inner surface of the nozzle.
• the overall nozzle consist of a plurality of hollow profiles which are fastened next to one another in a metal holder and act as outflow nozzles and consist of a difficult-to-melt, heat-resistant material, wherein in addition to the melt-guiding channels, parallel channels for heating the device are arranged.
• a heating it is possible to bring the nozzle to the required melt temperature before the start of casting. This can also happen so slowly that thermal shock does not occur or thermal chip can be derived.
• such a nozzle has a complicated structure and in particular the heating mechanism has a disruptive effect during operation, ie after the start-up process has ended.
• the inventor set himself the goal of developing a much simpler way of bringing a nozzle to the desired temperature with the metal to be cast before it actually starts up.
• At least one material with a different temperature than this metal is passed through the nozzle in front of the actual metal to be cast.
• this material (s) should have a higher temperature than the metal to be cast.
• This method has the advantage that only a small amount of "lead material” is needed, and also the contact time between the material and the nozzle can be briefly th g ehal-. However, this requires considerable experience about the thermal conductivity between the material used and the nozzle material.
• a material or materials should therefore preferably be used which have a lower temperature (t) than the metal to be cast. This prevents the nozzle from being brought to a temperature that is too high, so that the metal would also overheat and additional cooling in the mold would be necessary.
• Another metal is preferably used as the material which is to be passed through the nozzle in front of the actual metal to be cast.
• a metal is used for this, which is cheap.
• this metal Before being introduced into the nozzle, this metal can be brought to the desired temperature in a separate container, be it above or below that of the metal to be cast.
• a metal is preferably used which has a lower density than the metal to be cast. As a result, the nozzle and in particular its side delimiters are not suddenly exposed to excessive pressure when starting. If, for example, an iron metal, in particular steel, is cast, aluminum is suitable, which has a lower density than steel and whose oxide skin prevents the metal from penetrating into cracks or the like. prevented.
• the tundish upstream of the nozzle has several chambers for the different materials or metals and the metal to be cast.
• the nozzle can also be preceded by several separate pouring streams.
• This method makes it possible in a simple manner to bring already existing nozzles on casting machines to a desired temperature before starting and thus also to use a nozzle material which is relatively sensitive to thermal shock according to the methods used hitherto.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
• Continuous Casting (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=4245644

Family Applications (1)

Country Status (4)

Cited By (2)

Citations (3)

Family Cites Families (1)

• 1983
  • 1983-06-03 DE DE19833320131 patent/DE3320131A1/de active Granted
• 1984
  • 1984-05-17 EP EP84810242A patent/EP0127578A3/fr not_active Withdrawn
  • 1984-05-28 CA CA000455273A patent/CA1226418A/fr not_active Expired
  • 1984-05-31 JP JP11218084A patent/JPS606255A/ja active Pending

Patent Citations (3)

Non-Patent Citations (1)

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