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
  • B22D11/10—Supplying or treating molten metal
  • B22D11/11—Treating the molten metal
  • B22D11/114—Treating the molten metal by using agitating or vibrating means
  • B22D11/115—Treating the molten metal by using agitating or vibrating means by using magnetic fields
• • 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
  • B22D11/12—Accessories for subsequent treating or working cast stock in situ
  • B22D11/122—Accessories for subsequent treating or working cast stock in situ using magnetic fields

Definitions

• This invention relates to the continuous casting of steel, and more particularly to electromagnetic stirring of the still-molten and/or solidifying steel after pouring into a mould.
• a method of continuously downwardly casting steel including pouring the molten steel into a continuous casting mould and subjecting the still molten and/or solidifying steel after pouring to a helical electromagnetic force field.
• Such force can be upwardly helical whereby the radially outer part of the molten steel spirals upwards and the radially central portion spirals downwards relative to the metal strand, and conversely for a downward helical force.
• apparatus for the continuous downward casting of steel including a continuous casting mould and electromagnetic stirring means located about the metal strand path adjacent to the mould, the electromagnetic stirring means being adapted to subject still molten and/or solidifying steel to a helical force.
• helical force can be upwards or downwards.
• the helical stirring movement of the molten steel of the present invention has useful application with regard any continuous cast steel, and its value can be exampled by the continuous casting of aluminium treated steel.
• Two noteworthy problems in the casting of such steel are the need to avoid retaining inclusions of alumina in the steel as it is cast, and the need to ensure an outer surface layer around the strand free from included gas and entrapped slag.
• Previously proposed arrangements for horizontal, rotational, stirring of the steel suffer from the disadvantages, especially in the context of the above-mentioned aluminium treated steel, that inclusions tend to be trapped and retained below the surface of the steel by rotating stirring action.
• the helical stirring of the present invention enables all of these disadvantages to be overcome.
• the electromagnetic stirring may be provided by means of a plurality of electromagnetic coil assemblies located about the steel strand path, each being directed towards the strand path.
• the coil assemblies may be powered from a multi phased (e.g. three phased) electricity supply.
• the coil assemblies may be arranged in a series of rings about the steel strand path, adjacent assemblies in successive rings being phase shifted to provide the overall helical force field.
• the amount of phase shift between successive rings may vary axially of the arrangement so as to provide a varied angle helical field.
• the phase shift may be much greater at the upper portions of the stirring means, thereby providing a much more rotational force at the upper and a much more vertical force at the lower end of the steel being stirred.
• the series of rings may be capable of relative rotational adjustment so as to adjust the angle of the helical field.
• the coil assemblies in successive rings may be connected for switching phase sequences to provide a phase shift to adjust the angle of the helical force field.
• the electromagnetic stirring means may be disposed about the casting mould itself, or alternatively or additionally may be provided about the strand path below the mould. We believe the arrangement of the invention is particularly useful in casting steel of square sections of less than about 200mm. width.
• the helical stirring will be greatly facilitated if the electromagnetic body force can be made small on or near the strand axis by choosing an electromagnetic field configuration with a minimum of 2 pole pairs circumferentially, and the smallest pole pitch axially commensurate with achieving optimum performance.
• the relative value of input electrical energy is preferably of the order, between circumferential and axial of 0.2. This ratio preferably decreases for smaller sizes of strand and increases for larger sizes.
• Figure 1 is a diagrammatic sectional elevation of continuous steel casting apparatus according to the invention.
• Figure 2 is a section of the line II - II of Figure 1.
• 1 represents a tundish or similar vessel containing molten steel, located above and pouring steel 2 into a continuous casting mould 3.
• the mould 3 is shown, for ease of illustration, as being of circular plan. In practice, however, the mould would often be of a square or rectangular section.
• the mould is provided in the usual way with a water cooling annulus 10.
• each block 7 Located about the mould with annular end plates 8 are six sets of annular stator blocks 7 arranged one above the other, each block comprising six coil assemblies 5 disposed equi-angularly about the mould 3, each assembly 5 being provided with electrical windings (not shown). With a three-phase supply it will be appreciated that the six assemblies 5 in each block 7 may be connected to give a two pole or a four pole arrangement.
• Water cooling may be provided for the electromagnetic stirring means by means of interconnected water channels 6 disposed between and around assemblies 5. Water inlets 11 and outlets 12 are provided. Alternatively, water cooling may be provided by means of hollow windings for the assemblies 5 through which water is forced.
• a helical force field may be produced having a predetermined upward angle within the mould. Since the field is strongest adjacent the outer wall of the mould the field will have the effect of creating an upward helical stirring of metal around the radially outer portions of the liquid metal, and a returning downward helical in the radially inner portions of the liquid metal. It will be understood that any required length of stirring arrangement can be provided by using the required number of coil assemblies 5.

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

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Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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Cited By (6)

Families Citing this family (1)

Citations (3)

• 1980
  • 1980-03-20 WO PCT/GB1980/000047 patent/WO1980001999A1/en not_active Application Discontinuation
  • 1980-03-20 GB GB8037134A patent/GB2059835B/en not_active Expired
  • 1980-03-20 DE DE803038749T patent/DE3038749A1/de not_active Withdrawn
  • 1980-03-20 JP JP50062280A patent/JPS56500246A/ja active Pending
  • 1980-03-21 IT IT67434/80A patent/IT1128068B/it active
  • 1980-10-08 EP EP80900495A patent/EP0025047A1/en not_active Withdrawn
  • 1980-11-04 SE SE8007710A patent/SE8007710L/ not_active Application Discontinuation

Patent Citations (3)

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