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
  • B22D11/0665—Accessories therefor for treating the casting surfaces, e.g. calibrating, cleaning, dressing, preheating
  • B22D11/0668—Accessories therefor for treating the casting surfaces, e.g. calibrating, cleaning, dressing, preheating for dressing, coating or lubricating

Definitions

• TITLE METHOD FOR STRIP CASTING ALUMINIUM
• the present invention is concerned with a method for strip casting of aluminium where the surface of the aluminium strip is considerably improved and adhesion problems, so called sticking, against the casting roll are minimised.
• the cast surface is often to coarse with characteristic surface defects, which leads to product defects at the following cold rolling. Aluminium flakes are also accumulated in the rolling oil, which deteriorates the oil. The surface defects also have a direct connection to the tendency for sticking, i e the aluminium strip gets stuck in one of the casting rolls, which means that the process has to be interrupted.
• a lubricant e g graphite
• a lubricant is often applied on the casting rolls to ease the separation of the aluminium strip from the casting rolls.
• a lubricant Prior to start an abundant amount of lubricant is applied to the ground surfaces of the casting rolls, which are made of a specially developed steel material.
• the casting roll normally consists of a removable shell on a core containing cooling channels which provide the necessary and effective cooling.
• a coating of aluminium with an oxidised surface is building up on the clean steel surfaces of the casting roll. This coating does not completely cover the surface of the casting roll and the adhesion to the casting roll varies. The result is an uneven and coarse surface which is replicated on the aluminium strip.
• JP-57 56141 discloses a method of coating casting rolls with relatively thick layers of oxide or metal before rapid solidification of steel. Thick layers with a low heat conductivity are not acceptable in strip casting.
• GB- 1424205 discloses a method of solving problems with adhesion against the roll surfaces by covering these surfaces with a powder which does not give adhesion to the aluminium strip at the moment of casting, e g talc. The application of the powder has to be made continuously.
• GB-1507315 discloses the application of a steel casting strip in the so called "Hazelett- process" with an adherent ceramic layer.
• the purpose of this layer is to thermally insulate the casting strip, so that it does not get too warm due to contact with the aluminium melt, which would lead to a deformation of the casting strip.
• a second layer may be applied on top of the ceramic one to decrease the adhesion to the aluminium strip.
• the properties of the layer should not change, but remain constant. This is achieved by a continuous lubrication of the casting roll during the process. It is also important that the layer is stationary, e g that it is not removed from the roll during the progress of the casting process.
• the present invention is independent of the angle of the emerging strip against the ground plane.
• the aluminisation is made by for example plasma spraying, dipping in an aluminium melt, or jet spraying of aluminium powder.
• This layer may then be oxidised, e g by thermal oxidation or by a treatment with an oxidant or by anodizing.
• the thickness of the aluminized layer is limited to 100 ⁇ m . At a thickness above 100 ⁇ m the layer is deformed during the course of the process and surface defects are formed.
• the thickness is limited to 20 ⁇ m.
• a thickness above 20 ⁇ m will aggravate the heat transfer.
• the principle for strip casting aluminium is shown in figure 1.
• the melt (3) coming from the mouthpiece (2), solidifies against two cooled rotating casting strips (1) in a casting zone (5) before the solidified material is deformed in a rolling zone (6) to form a strip (4) with a thickness between 1 and 10 mm.
• Figure 2 shows one way of executing the invention.
• the shell (1) of the casting roll is coated before starting the casting process with a layer (7) which is not wetted by the solidifying melt, nor adheres to the solid aluminium strip when deformed.
• both casting rolls are covered with a layer of aluminium by plasma spraying.
• the roll is then heated in an oven using an atmosphere with a partial pressure of oxygen to oxidise the surface of the aluminium layer.
• a continuous casting can then be made without making the aluminium strip stick to the casting rolls and the surface quality is assured by adding graphite as a supplemental lubricant.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Continuous Casting (AREA)
• Metal Rolling (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20404315

Family Applications (1)

Country Status (3)

Cited By (2)

Citations (4)

• 1996
  • 1996-10-17 SE SE9603837A patent/SE9603837L/sv not_active Application Discontinuation
• 1997
  • 1997-10-16 AU AU47332/97A patent/AU4733297A/en not_active Abandoned
  • 1997-10-16 WO PCT/SE1997/001736 patent/WO1998016335A1/en active Application Filing

Patent Citations (4)

Non-Patent Citations (1)

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