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
  • B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
• • 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
  • B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
  • B22D11/0406—Moulds with special profile

Definitions

• the invention relates to a mould for continuous casting of metals, preferably steel, according to claim 1. Since the beginning of continuous casting with through- flow moulds, professional circles have dealt with problems relating to the creation of air gaps between the strand shell and the mould wall below the surface of the molten metal.Of course, this gap formation deteriorates the heat transfer between the mould and the strand shell considerably and causes an uneven cooling of the strand, which results in deficiencies in the billet, such as rhombic shape, cracks, structural defects, etc.
• US-A-4 207 941 describes a mould for the continuous casting of steel strands with polygonal, in particular square cross-sections.
• the cross-section of the mould cavity that is open at both sides, is at the inlet side a square with corner fillets and at the outlet side an irregular dodecagon.
• a jamming of the strand may easily arise, which may lead to a tearing up of the strand and a break ⁇ through.
• a dodecagon is moulded instead of a square. It is particularly difficult to dimension such moulds for different moulding speeds during a continuous moulding, which is necessary at long sequential mouldings with many changes of ladles.
• DE-A-3 907 351 a mould for continuous casting of a bloom is described. The two longitudinal sides are provided with
• CONFIRMATION PY bulges at the inlet side of the mould, which are continuously retrograded along a part height of the mould.
• the cross-section of the mould cavity is right- angled and provided with the desired bloom cross-section.
• the only purpose of the two bulges facing each other is to provide sufficient place for a moulding pipe. There are no bulges on the two narrow sides and also no shaping of the strand shell by means of the mould walls.
• AT-B-379 093 describes a mould for the continuous casting of a bloom.
• the circumference line of the cross-section of the mould cavity at the inlet side can be divided into four circumference sections.
• At two circumference sections at the inlet side, which simultaneously form the longitudinal sides of the bloom section, are provided cross-sectional enlargements with the shape of protruding bulges in relation with the same cross-section at the outlet side of the strand.
• the measure of the bulge which in this case corresponds to the arch height, diminishes continuously in the moving direction of the strand and is nil at the exit of the mould.
• the construction shall also make possible differences in the moulding rate during the process of casting.
• EP-A-498 296 has only partly managed to fulfil the posed problems.
• the reduction of the cross-sectional area has sometimes turned out to be too big, which has caused problems of jamming of the cast strand and of an increased mould wear.
• the chosen casting rate has turned out to be too high for this mould. It has been constructed in first hand for high rates, not for freedom from cracks and a generally faultless casting. However, it does not fully compensate for corner shrinkage, wherefore the corner design leaves more to be desired.
• the strand binds or "pinches" at lower casting rates.
• a primary object of the present invention is to compensate for the corner shrinkage of the strand, both at higher and lower casting rates.
• a further object of the present invention is to simplify the design of the mould as much as possible.
• Still another object of the present invention is to obtain an optimal contact between the strand and the mould wall along the whole length of the mould.
• a further object of the present invention is to compensate for the shrinkage gradient that arises between the inlet and outlet of the mould, thereby minimizing pull and pressure stresses.
• the mould has been given a shape that corresponds to the solidification behaviour of the material. This results in a better contact and thus a better support for the strand shell, and thereby an almost tension-free shell.
• the casting of crack-sensitive sorts is simplified and the risk of corner cracks in the corner regions, such as cross cracks, corner cracks and impressions is minimized.
• the risk of a rhombic* strand-shape is decreased, a problem that often arises, e.g., when casting blooms and billets.
• the construction according to the invention exposes the shell to a minimum of external influence and causes a very small mould wear (contrary to, e.g., AT-A-379 093), by the fact that the mould has a shape that substantially follows the free dimension variations of the strand during casting.
• Figure 1 shows a mould according to the invention in a perspective obliquely from above.
• Figure 2 shows a formalized view straight from above of two moulds according to the invention.
• Reference numeral 2 designates the inlet side of the mould and 3 designates its outlet side. Between these extends the mould cavity 4. It is suitably made of one sole, straight piece, although bowed moulds and block or plate moulds are also feasible.
• the mould is shaped with inner walls 5 which bulge inwards, towards the middle of the mould. At the top, at the inlet side 2 of the mould, they have a bending radius R ref , which within given ranges increases indefinitely towards the outlet side 3 of the mould.
• R' is the dimensionless radius
• R is the radius at the height z
• R ref is the radius at the inlet side (see fig 1)
• z' is the dimensionless distance from the upper side of the mould
• z is the factual distance from the upper side of the mould
• L is the total height of the mould.
• R(z) LR ref /(L-z) , or
• R(z) LR ref /(L-z) ; or dimensionless:
• the dimensionless radius shall suitably be within the following ranges along the vertical axis of the mould:
• the dimensionless radius lies within the following ranges:
• the mould shape goes from bulging sides and corner angles ⁇ larger than 90° at the inlet side, to a substantially square or rectangular shape at the bottom side of the mould.
• the corner angles ⁇ decrease downwards in a determined way, in order to obtain further advantages with regard to a minimized formation of cracks, increased casting rate and optimized heat transfer between the strand and the mould.
• the angle alteration should suitably be between 2 and 8°, preferably between 2 and 4°.
• fig 2 shows the cross-sectional shape of the mould cavity 4 at the inlet side 2 and the outlet end 3, respectively, of the mould.
• the cross-section of the inlet side corresponds to line 6 while the cross-section of the outlet end is substantially rectangular and is depicted either by the rectangle 7 or 8.
• the corner distance of the mould in one direction may be lar,ger at the lower edge of the mould than at the upper edge, i.e. the mould may to some extent obtain an inverted conicity.
• the mould should have some conicity in order to compensate for the cooling shrinkage of the arising strand shell, and whose reduction of the corner distance may be added to the extension of the corner distance that occurs when the bulging side surface 5 is gradually straightened out.
• the bulginess of the mould walls start 5 to 40 mm from the corners 9, as measured along the substantially planar wall portion 10; preferably 10 to 30 mm.

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

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (7)

Cited By (6)

Citations (4)

• 1995
  • 1995-05-09 SE SE9501709A patent/SE516076C2/sv not_active IP Right Cessation
• 1996
  • 1996-05-07 WO PCT/SE1996/000598 patent/WO1996035533A1/en not_active Application Discontinuation
  • 1996-05-07 CA CA002219910A patent/CA2219910A1/en not_active Abandoned
  • 1996-05-07 AU AU57092/96A patent/AU5709296A/en not_active Abandoned
  • 1996-05-07 BR BR9608283A patent/BR9608283A/pt not_active Application Discontinuation
  • 1996-05-07 JP JP8533996A patent/JPH11504864A/ja active Pending
  • 1996-05-07 KR KR1019970707985A patent/KR19990008455A/ko not_active Application Discontinuation

Patent Citations (4)

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