Patent Application
20070095499
The present invention relates to the continuous casting of metal strip, and more particularly, to the electromagnetic confinement of molten metal in a continuous casting system.
Continuous casting of metals is performed in twin-roll casters and belt casters or combinations thereof. Methods are available for casting both in the horizontal and in the vertical direction. In particular, the steel industry has recently developed high speed twin roll strip casters which operate in the vertically down direction.
Up to the present, the mechanical edge dams have been employed to provide containment of the molten metal in the casting zone. Such devices have included the caterpillar type edge dams that move with the strip (as in the Hazelett casters) or fixed edge dams that are pressed against the surface of the rolls. The latter is used in the twin-roll steel strip casting industry. Such fixed mechanical edge dams have a short service life as they get eroded by contact with the cold sidewall of the rolls. In addition, such mechanical edge dams provide sites for the formation of skulls that have a tendency to be sheared off and thus enter the cast strip to render the microstructure metallurgically undesirable. Caterpillar edge dams, while well proven for the thicker slab castings (10-25 mm thick), become impractical for thin strip casters or twin drum casters of the steel industry where the cross section to be contained changes sharply along the casting zone.
Electromagnetic edge dams have been employed in the prior art in the strip casting of metals in vertical twin drum (roller) casting systems. Electromagnetic edge dams of a magnetic system type use a combination of a magnet assembly and an AC coil to generate confinement forces. Electromagnetic edge dams of an induction system type rely solely on an AC coil to generate the containment forces.
The magnetic system electromagnetic edge dams use a magnetic member which comprises a yoke or core connecting two pole faces disposed on either side of the gap on which the molten metal is to be confined. The magnetic member is made of a ferromagnetic material and is surrounded over a given length of the yoke by a coil carrying an AC current. The magnetic flux generated by the flow of the current into the coil is transmitted to the poles of the magnet through the yoke and establishes containment forces at the metal surface in the gap.
Typically, in magnetic systems, part of the magnetic member is covered with an electrically conductive shield to minimize leakage of flux in a direction away from the gap. Such magnetic confinement systems have the advantage that the confinement current need not be as high as compared to those systems using solely an induction coil. If a stronger magnetic field is required, it can be achieved with the same current level by reducing the area of the pole faces to concentrate the field. However, such systems are not without disadvantages. For example, such systems typically have poor operating efficiency resulting from core losses and losses due to magnetic hysterisis when an alternating magnetic field is applied to the magnetic material. Additionally, high temperatures are typically generated that need to be dissipated by cooling in order to prevent damage to the magnetic system.
Induction confinement systems typically employ a shaped inductor positioned close to the gap in which the molten metal is to be contained. The AC current flowing in the inductor generates induced currents as well as a time-varying magnetic field on the surface of the molten metal to be contained. The interaction between the current and the magnetic field provide containment forces. To improve efficiency, a magnetic member is built around the inductor to focus the current to the inductor surface facing the molten metal. Induction coil systems are generally simpler in design than magnetic systems. However, induction systems are disadvantageously limited in terms of the maximum metallostatic head that can be contained by the system. The maximum metallostatic head that can be supported in induction coil systems is limited, because induction coil systems require very high inductor currents to provide adequate containment forces, wherein such high currents are accompanied by increased heat generation, which in turn hinders or slows the solidification process during casting.
Referring to
U.S. Pat. No. 4,936,374 describes a vertical casting system and electromagnetic confinement apparatus having the disadvantages described above. Further, U.S. Pat. No. 4,936,374 describes casting rollers having a rim portion, in which the containment magnetic field is conducted through the rim portion of the casting roll. In addition to induction heating and wave generation, the rim portions of the casting rolls disclosed in U.S. Pat. No. 4,936,374 produce a ridge in the cast product and therefore fail to provide a casting strip having uniform sidewalls (edges). The ridge formed in the casting strip produced using the apparatus and method disclosed in U.S. Pat. No. 4,936,374 must be machined prior to rolling of the casting strip. Additional machining disadvantageously adds to the cost of the production.
Accordingly, a need remains for a method of high-speed continuous casting of metals and alloys, which achieves uniformity in the cast strip surface, provides good molten metal containment in the casting zone, and results in strip edges which can be rolled without needing to be machined by trimming.
The present invention overcomes the above-described obstacles and disadvantages by providing an electromagnetic confinement apparatus incorporated into a horizontal casting apparatus, wherein the positioning of the electromagnetic confinement apparatus and a magnetic field that is produced by an alternating current provides a cast metal strip having substantially uniform edges (sidewalls). The present invention further provides a method and apparatus for producing a cast metal strip, which provides a means for adjusting the profile of the cast metal strip's sidewall.
In one embodiment of the present invention, the current applied through the electromagnetic confinement apparatus, as well as, the positioning of the electromagnetic confinement apparatus to the molding zone of the horizontal casting apparatus is selected to provide a cast metal strip having substantially uniform edges, in which the sidewall of the cast metal strip edges may be substantially flat, or concave or convex in relation to the cast metal strip's centerline. The cast metal strip's substantially uniform edges allows for the cast metal strip to be rolled without further machining. Broadly, one embodiment of an apparatus of the present invention comprises:
In another embodiment of the apparatus of the present invention, a horizontal roller casting apparatus is provided in which containment of the metal through the apparatus is provided by the combination of a mechanical edge dam and an electromagnetic edge dam. Broadly, the inventive casting apparatus comprises:
In each embodiment, the vertical distance separating the horizontally disposed pair of casting rollers provides a metal head height that allows for containment of the molten metal by magnetic lines of force that are provided by an electromagnetic containment device without a substantial increase in the temperature of the molten metal. For the purposes of this disclosure, the term “positioned distal from and aligned to a sidewall of said pair of casting rollers” is intended to denote that the poles of the electromagnetic edge dam do not extend towards the casting apparatuses centerline beyond a plane defined by the sidewall of the casting rollers, but are positioned within close enough proximity to the castings roller's sidewall to provide a sufficient magnetic field to contain molten metal within the molding zone. It is noted that the poles of the electromagnetic edge dam may be adjusted from adjacent to the casting rollers sidewall to any distance from the sidewall, so long as sufficient containment forces are provided by the poles to the molding zone. In one embodiment, the sidewall of the casting roller may be substantially planar. The term “substantially planar” with respect to the casting roller's sidewall denotes that the casting roller does not incorporate a lip portion. In one embodiment, the electromagnetic lines of force are produced by an alternating current having a frequency ranging from 40 Hz to 10,000 Hz through the electromagnetic edge containment device.
In another embodiment of the present invention, a belt casting system is provided that employs electromagnetic edge containment and produces a metal strip having substantially uniform edges, wherein the substantially uniform edges allows for the cast metal strip to be rolled without further machining. Broadly, the inventive belt casting system for strip casting of molten metal comprising:
In another aspect of the present invention, a casting strip is provided that may be formed by the above casting apparatus. Broadly, the cast strip comprises:
In another aspect of the present invention, a method is provided for casting a metal strip in which a magnetic field is utilized to control the geometry of the metal strip's sidewall. Broadly, the inventive method comprises:
The magnetic field may be adjusted to provide a metal casting strip sidewall geometry that is flat or is concave or convex relative to the centerline of the cast metal strip. In one embodiment, the magnetic containment means may include an induction coil wound about a magnetic member to generate magnetic lines of force upon application of a current. The magnetic member having a first and second magnetic pole positioned distal from to adjacent to the molding zone.
The magnetic lines of force produced by the magnetic containment means may be adjusted by increasing or decreasing the current through the induction coil or by changing the positioning of the magnetic containment means relative to the molding zone. Positioning the first and second magnetic poles of the magnetic containment means adjacent to-the molding zone may produce a cast metal strip having a concave sidewall and positioning the first and second magnetic poles of the magnetic containment means distal from the molding zone may produce a cast metal strip having a convex sidewall.
a (side cross sectional view) is a schematic of one embodiment of a horizontal casting apparatus having electromagnetic edge dams in accordance with the present invention.
b (side cross sectional view) depicts one embodiment of a twin belt caster equipped with an electromagnetic edge dam apparatus in accordance with the present invention.
a-7d provide a sectional view of the electromagnetic edge dam apparatus of the present invention illustrating the path of the magnetic lines of force in relation to the roller casters of the horizontal roller caster casting apparatus.
a-c (side view) illustrate different pole face angles and orientations in accordance with the present invention.
a-c are pictorial representations of sidewall of a casting strip.
a-b are photographic representations of the edges of the strip made with a high magnetic force in the electromagnetic dam.
The present invention provides an electromagnetic edge dam that confines molten metal to the molding zone of a horizontally disposed roller casting or belt casting system with a magnetic field that is produced by a lower AC current than was previously possible. By providing sufficient electromagnetic containment means at lower AC currents, the present invention utilizes electromagnetic confinement without creating a substantial increase in the temperature of the molten metal or producing wave generation effects.
As discussed above, in prior vertical casting methods with larger molten metal head height, larger magnetic forces are required in order to contain the greater pressure produced by the molten metal, wherein larger magnetic forces typically require higher currents that generate heat. For example, to contain molten aluminum against a 300 mm height, as representative of typical vertical casting methods, a minimum magnetic field intensity of 0.24 T would be needed. In the present invention, the metal head height is kept low, as achieved by a horizontally disposed casting system, so that the required containment can be met with relatively low magnetic field density. For example, a 50 mm head height in a horizontal casting apparatus consistent with the present invention requires a magnetic field density of only 0.055 T to contain molten aluminum in the horizontal position while casting. The present invention is now discussed in more detail referring to the drawings that accompany the present application. In the accompanying drawings, like and/or corresponding elements are referred to by like reference numbers.
Referring to
Referring to
Referring to
The molten metal M delivered from the feeding tip T directly contacts the cooled rolls R1 and R2 at regions 18 and 19, respectively. Upon contact with the rolls R1 and R2, the metal M begins to cool and solidify. The cooling metal produces an upper shell 16 of solidified metal adjacent the roll R1 and a lower shell 17 of solidified metal adjacent to the roll R2. The thickness of the shells 16 and 17 increases as the metal M advances towards the nip N. Large dendrites 21 of solidified metal (not shown to scale) are produced at the interfaces between each of the upper and lower shells 16 and 17 and the molten metal M. The large dendrites 21 are broken and dragged into a center portion 12 of the slower moving flow of the molten metal M and are carried in the direction of arrows C1 and C2.
The dragging action of the flow can cause the large dendrites 21 to be broken further into smaller dendrites 22 (not shown to scale). In the central portion 12 upstream of the nip N, the metal M is semi-solid including a solid component including solidified small dendrites 22 and a molten metal component. The metal M in the region 23 has a mushy consistency due in part to the dispersion of the small dendrites 22 therein. At the location of the nip N, some of the molten metal is squeezed backwards in a direction opposite to the arrows C1 and C2. The forward rotation of the rolls R1 and R2 at the nip N advances substantially only the solid portion of the metal (the upper and lower shells 16 and 17 and the small dendrites 22 in the central portion 12) while forcing molten metal in the central portion 12 upstream from the nip N such that the metal is completely solid as it leaves the point of the nip N.
Downstream of the nip N, the central portion 13 is a solid central layer 13 containing the small dendrites 22 sandwiched between the upper shell 16 and the lower shell 17. In the central layer 13, the small dendrites 22 may be about 20 to about 50 microns in size and have a generally equaixed (globular) shape, as opposed to having a columnar shape. The three layers of the upper and lower shells 16 and 17 and the solidified central layer 13 constitute a solid cast strip.
The rolls R1 and R2 serve as heat sinks for the heat of the molten metal M. In the present invention, heat is transferred from the molten metal M to the rolls R1 and R2 in a uniform manner to ensure uniformity in the surface of the cast strip. Surfaces D1 and D2 of the respective rolls R1 and R2 may be made from a material of good thermal conductivity such as steel or copper or other metallic materials and are textured and include surface irregularities (not shown) which contact the molten metal M. The surface irregularities may serve to increase the heat transfer from the surfaces D1 and D2. The rolls R1 and R2 may be coated with a material to enhance separation of the cast strip from the rolls R1 and R2 such as chromium or nickel. In a preferred embodiment, the rolls R1 and R2, including surfaces D1 and D2, comprise a ferromagnetic material. In the embodiments of the present invention, in which the rolls R1 and R2 do not comprise a ferromagnetic material, the casting surfaces D1, D2 of the roller as well as the roller's sidewall may be coated with a ferromagnetic materials.
The control, maintenance and selection of the appropriate speed of the rolls R1 and R2 may impact the operability of the present invention. The roll speed determines the speed that the molten metal M advances towards the nip N. If the speed is too slow, the large dendrites 21 will not experience sufficient forces to become entrained in the central portion 12 and break into the small dendrites 22. Accordingly, the present invention is suited for operation at high speeds such as about 25 to about 400 feet per minute or about 100 to about 400 feet per minute or about 150 to about 300 feet per minute. The linear speed that molten aluminum is delivered to the rolls R1 and R2 may be less than the speed of the rolls R1 and R2 or about one quarter of the roll speed. High-speed continuous casting according to the present invention may be achievable in part because the textured surfaces D1 and D2 ensure uniform heat transfer from the molten metal M.
The roll separating force may be a parameter in practicing the present invention. The roll separating force is the force present between the rolls due to the presence of the strip within the roll gap. The roll force is particularly high when the strip is being plastically deformed by the rolls during roll casting. A significant benefit of the present invention is that solid strip is not produced until the metal reaches the nip N. The thickness is determined by the dimension of the nip N between the rolls R1 and R2. The roll separating force may be sufficiently great to squeeze molten metal upstream and away from the nip N. Excessive molten metal passing through the nip N may cause the layers of the upper and lower shells 16 and 17 and the solid central portion 13 to fall away from each other and become misaligned. Insufficient molten metal reaching the nip N causes the strip to form prematurely as occurs in conventional roll casting processes. A prematurely formed strip 20 may be deformed by the rolls R1 and R2 and experience centerline segregation. Suitable roll separating forces are about 25 to about 300 pounds per inch of width cast or about 100 pounds per inch of width cast. In general, slower casting speeds may be needed when casting thicker gauge aluminum alloy in order to remove the heat from the thick alloy. Unlike conventional roll casting, such slower casting speeds do not result in excessive roll separating forces in the present invention because fully solid aluminum strip is not produced upstream of the nip.
In prior applications, roll separating force has been a limiting factor in producing low gauge aluminum alloy strip product but the present invention is not so limited because the roll separating forces are orders of magnitude less than in conventional processes. Aluminum alloy strip may be produced at thicknesses of about 0.1 inch or less at casting speeds of 25 to about 400 feet per minute. Thicker gauge aluminum alloy strip may also be produced using the method of the present invention, for example at a thickness of about ¼ inch.
The aluminum alloy strip 20 continuously cast according to the present invention includes a first layer of an aluminum alloy and a second layer of the aluminum alloy (corresponding to the shells 16 and 17) with an intermediate layer (the solidified central layer 13) therebetween. The grains in the aluminum alloy strip of the present invention are substantially undeformed because the force applied by the rolls is low (300 pounds per inch of width or less). The strip is not solid until it reaches the nip N; hence it is not hot rolled in the manner of conventional twin roll casting and does not receive typical thermo-mechanical treatment. In the absence of conventional hot rolling in the caster, the grains in the strip 20 are substantially undeformed and retain their initial structure achieved upon solidification, i.e. an equiaxed structure, such as globular.
Continuous casting of aluminum alloys according to the present invention is achieved by initially selecting the desired dimension of the nip N corresponding to the desired gauge of the strip S. The speed of the rolls R1 and R2 may be increased to a desired production rate, or to a speed that is less than the speed at which the roll separating force increases to a level that indicates that plastic deformation of the casting strip is occurring between the rolls R1 and R2. Casting at the rates contemplated by the present invention (i.e. about 25 to about 400 feet per minute) solidifies the aluminum alloy strip about 1000 times faster than aluminum alloy cast as an ingot cast and improves the properties of the strip over aluminum alloys cast as an ingot.
The molten metal M being delivered from the feed tip T is confined within the molding zone 20 by at least an electromagnetic edge dam 15 that is positioned to direct magnetic lines of force perpendicular to the plane 2-2 on which the casting is being drawn. In one embodiment, an electromagnetic edge dam 15 is positioned on each side of the casting apparatus. In a preferred embodiment, the molten metal M is confined within the molding zone 20 during casting by a mechanical edge dam 55 in combination with an electromagnetic edge dam 15, wherein the mechanical edge dam 55 is positioned proximate to the feed tip T and the electromagnetic edge dam 15 is positioned overlying the terminating end of the mechanical edge dam 55 and provides confinement forces along the entire length of the molding zone 20, as depicted in
The current and/or frequency utilized by the electromagnetic edge dam 15 to maintain the molten metal M within the molding zone 20 is substantially less than typically required in prior casting apparatuses using electromagnetic edge dams. In prior casting apparatus employing electromagnetic edge dams, high magnetic force fields where required to contain the molten metal, which resulted in induction heating within the molten metal that disadvantageously effected the solidification process. In the present invention, by reducing the magnitude of the required electromagnetic force, the current and/or frequency conducted through the electromagnetic edge dam is also reduced, which in turn advantageously reduces the incidence of induction heating on the sidewall of the molten metal in the molding zone.
Without wishing to be bound, but in the interest of further describing the present invention, applicants' believe that the reduction in the electromagnetic force that is required to contain the metal within the molding zone is related to the decreased head height H2 of the molten metal from the feed tip T, as depicted in
The relationship between the height of the molten metal head H2 and the magnetic field density required for containing molten aluminum at different head levels is best described through the following equations. First, the pressure exterted by the molten metal head, which the magnetic field must contain within the molding zone 20 is calculated from:
p=ρgH2
The pressure required to contain the molten metal head H2 within the molding zone 20 is then used in the following equation to determine the required magnetic field density (B):
p=B2/2μo
In another aspect of the present invention, the physical positioning of the electromagnetic edge dam, the molten metal head height and the strength of the magnetic field can be varied to control the positioning of the edge of the molten metal within the molding zone with respect to the roller casters R1, R2 sidewall. The strength of the magnetic field at different distances from the face (edge) of the roller casters may be calculated by the following equation:
BL=(μo nI/1)/{(2D/H)sin h(L/1)+(w/1)cos h(L/1)}
Referring to
The edge of the casting strip can therefore be contained inwards from the casting roll R1, R2 face (sidewall), if desired, by increasing the current in the edge dam. It is noted that the field density decreases rapidly at longer distances from the roll face and only small metal head heights, on the order of 50 mm, can be contained in distances 40 mm or greater by the operation of this edge dam at 2000 amp turns. The range of containment can be extended further, if needed, by increasing the magnetomotive force (nI) on the edge dam. When increasing the electromagnetic force, due consideration need to be given to the heating effect of the edge dam.
It is further noted that the plot depicted in
In addition to the height of the molten metal head and the magnetic field density, the positioning of the electromagnetic edge dam with respect to casting rollers may also be adjusted to provide electromagnetic force lines to confine the molten metal M within the molding zone 20. Referring to
The inventive electromagnetic edge dam will also perform in casters with rolls made from a non-magnetic (non-ferromagnetic) material, such as copper. However, when the rollers comprise a non-magnetic material, the penetration of the magnetic field into the roll gap may be limited and thus containment will typically occur on a plane close to the end of of the rolls. It may be possible to obtain penetration into the gap by coating with a ferromagnetic material (such as iron, nickel or cobalt) the end faces and casting surfaces 200 of such rolls to the required depth of containment, as depicted in
It is noted that prior casting apparatuses typically shape the magnetic poles of the electromagnetic devices and the casting rolls to focus the magnetic field towards the molding zone. In one example, prior casting rollers employ lips extending from the sidewall of each roller and may have further included magnetic poles having a geometry corresponding to the extending lips of prior casting rollers. Contrary to prior casting apparatuses, the present invention does not require specially configured casting rollers to facilitate the focus of the magnetic field produced by the electromagnetic edge dam. In one embodiment of the present invention, the sidewalls 113 of the casting rollers R1, R2 may be substantially planar. Further, the electromagnetic edge dam 15 of the present invention may be positioned so that the face of the electromagnetic edge containment device is aligned to the face of the casting roller's planar sidewall 113, wherein the electromagnetic edge dam 15 is in close proximity to the casting rollers R1, R2. The electromagnetic edge dam 15 may also be positioned distal from the casting roller's sidewall 113. Regardless of the positioning of the electromagnetic edge dam 15, the electromagnetic edge dam 15 is positioned to provide sufficient electromagnetic force to contain the molten metal M within the molding zone 20.
The positioning of the edge dams 15 may be dependent on the current or frequency utilized in the edge dam. For example, lower currents may provide lower magnitude electromagnetic force line and therefore be more likely to require that the edge dam 15 be positioned in closer proximity to the molding zone 20. The higher the current conducted through the electromagnetic edge dam the greater the magnitude of the electromagnetic force lines and hence the father away the electromagnetic edge dams may be positioned from the molding zone.
Referring to
In another embodiment, the electromagnetic edge dam 15 may be configured to provide molten metal within the molding zone having a convex sidewall relative to the centerline of the molten metal M within the molding zone 20. Preferably, the sidewall of the molten metal within the molding zone is substantially aligned to the planar surface of the roller casters, as depicted in
The electromagnetic edge dam's 15 structure is illustrated in detail in
Still referring to
a-9c illustrate different pole face 44 angles and orientations in accordance with the present invention. It will be appreciated by those skilled in the art that as the inter-pole-face gap 43 increases, the strength of the field across the gap decreases.
In one embodiment of the present invention, the magnetic member 30 is formed from a ferromagnetic material such as silicon steel, and can be formed from a solid piece of such ferromagnetic material. Alternatively, the magnetic member 30 can be formed from multiple ferromagnetic materials, such as the split core design depicted in
Referring back to
The electromagnetic edge dam employed in the practice of the present invention also includes an inner shield 56 dimensioned to fit within the C-shaped configuration of the magnetic member 30. The inner shield 56 likewise serves to contain the magnetic lines of force generated by the coil 38 of the magnetic member 30, insuring that the magnetic lines of force are maintained within the magnetic member 30. In addition, it is also possible, and some times desirable, to include within the inner shield conduit means for the passage of a cooling fluid therethrough where it is desired to increase the ability to dissipate heat from the magnet. It is also possible to do away with the inner shield; especially so when using grain oriented silicon steel laminates where the field lines prefer to flow within the laminates.
The path of the magnetic field of the present invention is indicated in
In designing the electromagnetic containment apparatus employed in the practice of this invention, a number of different techniques can be used in dissipating heat generated by the electromagnetic field. As shown in
The following examples are provided to further illustrate the present invention and demonstrate some advantages that arise therefrom. It is not intended that the invention be limited to the specific examples disclosed.
Aluminum strip was cast in accordance with the present invention using a caster with steel rolls. The strip was then metallographically tested to confirm the effect of the electromagnetic force on the molten metal within the molding zone. Test specimens were formed using a horizontal roller caster and a combination of electromagnetic and mechanical edge dams consistent with the present disclosure. Casting strips of three different thicknesses (2.44 mm, 2.29 mm, and 2.16 mm) were then cast operating the electromagnetic edge dam at 2180 A turns. Samples were then cut from the edges of the strips and were prepared for metallographic examination. It was observed that the center part of the casting strip was pushed inwards as compared to the outer surfaces of the strip, as shown in
The depth of the confinement effect into the roll gap was estimated by first measuring the width of the casting strip at room temperature, wherein the width of the casting strip was approximately 400.5 mm. From this measurement, the width of the strip within the molding zone can be estimated as 406 mm by adding the contraction that occurred during solidification and cooling to room temperature.
Taking into account that the width of the casting roll is approximately 432 mm, it is evident that the magnetic field pushed the molten center of the casting strip a distance of approximately 13 mm (13 mm=(432(width of roller caster)−406)/2) from the casting roll face on each side of the casting roll. More specifically, by subtracting the calculated width of the casting strip in the molding zone from the width of the casting roller the total displacement produced by the electromagnetic edge dams is calculated. The amount of displacement produced by a single edge dam is calculated by the number of edge dams employed, which in this experiment consisted of two electromagnetic edge dams positioned at opposing ends of the casting rollers.
Similar electromagnetic push effects were observed for all three different strip thickness (strip gauge), as summarized in the Table depicted in
The edge profile of the as-cast strip was checked for operation at different magnetomotive force levels in the electromagnet. The edge profile obtained at 2180 A turn operation shown in
A flat edge profile was obtained in the casting strip at a current level of 180 A (or 1620 A turns) being applied to the electromagnet. To obtain a flat edge profile, the magnetic field should be selected to just offset the pressure produced by the molten metal in the molding zone, which is produced by the metal head with a minor contribution small roll pressure. Referring to
This strip was rolled in-line successfully through four stands of rolling mills. The casting strip was rolled from a 2.7 mm (0.107 inch) as-cast thickness to a thickness of approximately 0.36 mm (0.014 inch), which corresponded to an 87% reduction in thickness. Referring to
Following proper adjustment of the electromagnetic edge dam, high quality edges are obtained in the as-cast strip which permits rolling to high reduction ratios saving materials and improving the efficiency of the process.
While the present invention has been particularly shown and described with respect to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in forms and details may be made without departing from the spirit and scope of the present invention. It is therefore intended that the present invention not be limited to the exact forms and details described and illustrated, but fall within the scope of the appended claims.
