EP0081848B1 - Method and apparatus for shaping the casting region in a twin-belt continuous casting machine - Google Patents

Method and apparatus for shaping the casting region in a twin-belt continuous casting machine Download PDF

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Publication number
EP0081848B1
EP0081848B1 EP82111600A EP82111600A EP0081848B1 EP 0081848 B1 EP0081848 B1 EP 0081848B1 EP 82111600 A EP82111600 A EP 82111600A EP 82111600 A EP82111600 A EP 82111600A EP 0081848 B1 EP0081848 B1 EP 0081848B1
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EP
European Patent Office
Prior art keywords
casting
rollers
metal
molten metal
product directly
Prior art date
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EP82111600A
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German (de)
English (en)
French (fr)
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EP0081848A2 (en
EP0081848A3 (en
Inventor
Robert W. Hazelett
Samuel R. Hazelett
John F. B. Wood
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Hazelett Strip Casting Corp
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Hazelett Strip Casting Corp
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Publication of EP0081848A2 publication Critical patent/EP0081848A2/en
Publication of EP0081848A3 publication Critical patent/EP0081848A3/en
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    • 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
    • B22D11/0677—Accessories therefor for guiding, supporting or tensioning the casting belts

Definitions

  • This invention relates to continuous casting machines for continuously casting metal ingot, strip, slab or bars directly from molten metal in a casting region defined between spaced portions of a pair of revolving, flexible, endless casting belts which are moved along with the metal being cast, often called twin-belt casting machines or twin-belt casters.
  • the invention is described as embodied in the structure and operation of twin-belt casting machines in which the molten metal is fed into a casting region between opposed, portions of a pair of moving, flexible belts.
  • the moving belts confine the molten metal between them and carry the metal along as it solidifies into a bar, strip, slab, or ingot, hereinafter called the "cast product" or “product being cast” or similar words.
  • Back-up means usually rollers having narrow circumferential ridges or fins support and guide the belts while holding them accurately positioned and aligned as they move along so as to produce the cast metal product.
  • These back-up rollers are positioned across the machine carriages so as to roll passively when the casting belt grazes each of them under pressure of the head of molten metal and/or the weight of the metal.
  • Their circumferential fins permit the passage of cooling liquid along the respective casting belt without notably impeding heat transfer themselves.
  • the fins have often been made separately from the roller shafts, but in current machines the fins and shafts are now often made integrally as one piece of metal.
  • Vast quantities of heat liberated by the molten metal as it solidifies are withdrawn through the portions of the two belts which are adjacent to the metal being cast. This large amount of heat is withdrawn by cooling the reverse surfaces of the belts by means of the rapidly moving liquid coolant traveling along these surfaces.
  • the moving belts are thin and are cooled by substantial quantities of liquid coolant, usually water containing corrosion inhibitors.
  • This coolant withdraws heat through the casting belts and serves to cool the metal from its molten state as it enters at one end of the machine causing it to solidify as it passes through the machine.
  • the molten metal pushes ouwardly on the belts due to metalostatic pressure or "head".
  • Solidification of the metal product takes place from outside to inside so that, through some of its passage through the machine, it is in the form of a solidified shell having a molten, constantly decreasing, interior volume. It will also be understood that, as the metal cools and solidifies, it shrinks. The shrinkage is very slight but, nevertheless, is sufficient to cause surface regions of the metal sometimes to pull away from the moving belts or from the side dams. When this separation between areas of the metal surface and the cooling surface occurs, non-uniform cooling is caused, which results in non-uniformities in the parameters of the casting region and in non-uniformities in the cast product.
  • This invention in certain aspects is especially applicable to casting machines which produce ingot or slab of a width in excess of 25 inches (635 mm).
  • Such twin-belt casting machines are generally inclined downward in use, so as to result in a head-that is, a static pressure-of liquid metal in order to fill out the casting region, i.e. the mold cavity, and to thereby press the casting belts decisively against their back-up supports.
  • a head-that is, a static pressure-of liquid metal in order to fill out the casting region, i.e. the mold cavity, and to thereby press the casting belts decisively against their back-up supports.
  • open-or closed-pool pouring technique the entry of molten metal into the machine is facilitated by operating the machine at some downward incline.
  • the aforesaid head of molten metal depends on the angle of incline, the density of the molten metal being cast, and the distance to the point of final solidification in the machine.
  • the very rigidity of the above described prior art back-up means can combine with the shrinkage inherent in the freezing and cooling of the product being cast to allow air spaces to intervene between the freshly cast surface and the casting belts. These intruding spaces substantially reduce the rate of heat transfer and may render it non-uniform, with a corresponding effect on the rate and uniformity of product cooling and solidification.
  • the reduced rate and uniformity of cooling limits the production rate, or else it requires the use of longer casting machines than would otherwise be needed.
  • air spaces or gaps occurring between the cast metal surface and the mold surfaces defining the casting region is the consequent degradation of the desired fine, quick-chilled crystalline structure in the cast product into coarser crystals.
  • air spaces or gaps can permit the localized remelting of the cast product with consequent bleeding, or sweating of molten material from the previously cast shell itself and/or from the molten metal inside of the shell causing segregation and/or porosity in the cast product. This reheating or remelting will not occur if good mold contact is maintained.
  • Continuous casting methods and systems are advantageously provided wherein the contact pressures between the casting belts and the metal product are controlled and are maintained along the length of the metal to insure uniform heat extraction from the solidifying metal product.
  • One preferred method of shaping the casting region by action of the back-up system is to arrange for constant parallel thickness in the upstream casting region, before the product being cast is solidified enough to retain its shape, and to allow springy bowable rollers and back-up supports to converge in the downstream portion of the casting region as the largely solid product contracts due to loss of heat.
  • the "head" of the molten metal is predetermined and is used as the driving force for bowing or deflecting the back-up rollers and their support systems in one carriage only, preferably those in the upper carriage while the back-up rollers and support systems in the other carriage are rigid; and predetermined bowability is intentionally provided in the back-up rollers and in their support systems in said one carriage for responding to this force of the head of molten metal, while the back-up rollers in the other carriage are rigidly constrained.
  • mechanical adjustment means are used for applying bending forces to the back-up rollers and/or to their support systems for producing bowing of the back-up rollers in one or both carriages for shaping the casting region.
  • remotely controllable bowing means are used for controllably applying bending forces to the bowable back-up rollers in one or both carriages for shaping the casting region.
  • a first one of the casting belts is flexibly constrained in a predetermined relationship versus the molten metal head values occurring at different locations in the downwardly inclined casting region for enabling this first belt to bow transversely away from the casting centerline due to the predetermined molten metal head values occurring at the various locations, with the second casting belt being rigidly constrained and being transversely bowed toward the casting centerline in a predetermined inward convex configuration that compensates for the various displacements of the flexibly constrained belt, resulting in a uniform transverse cross section for the cast product, while providing improved casting parameters.
  • methods and systems are provided for casting metal product directly from molten metal in order to promote uniform heat transfer from the cast metal to the belts which are continuously liquid cooled.
  • the upper back-up rollers are selectively bowed down either by manual adjustment or by remote control, and the lower back-up rollers are allowed to yield or "float", or vice versa.
  • the methods and systems as disclosed include intentionally rigidizing the upper or lower.back-up rollers or sections thereof while the back-up rollers on the other side are allowed to flex in predetermined amounts with the surface of the casting.
  • These methods and systems include bowing both sets of the back-up rollers either inwardly or outwardly; bending structural frame members which are in support relationship with the rollers for flexing the rollers to control belt contour and belt contact with the cast product, etc.
  • the maintenance of contact between the casting belts and the cast product is controlled by either manual adjustment or remote actuation.
  • the mold configuration may be tapered from the upstream to the downstream end of the continuous casting machines for compensating for shrinkage in the solidifying metal and for providing predetermined mold contact pressures and heat transfer characteristics.
  • a continuous casting machine referred to generally with the reference character 10, has molten metal fed into the upstream end or entry 11 of the machine 10 between upper and lower endless flexible casting belts 12 and 14.
  • the molten metal is solidified in a casting region C ( Figure 3) defined by the spaced parallel surfaces of the upper and lower casting belts 12 and 14.
  • Figures 1,2,3,4 and 5 show prior art structures, and it is helpful to the reader to understand these prior structures as background for the present invention.
  • the casting belts 12 and 14 are supported and driven by means of upper and lower carriage assemblies which are indicated in Figures 1, and 3 at U and L, respectively.
  • the carriage assemblies are supported in cantilever relationship from a main frame 23, as seen in Figure 1. Hence the side of each carriage assembly near this main frame 23 is referred to as being "inboard” while the other side is referred to as "outboard”.
  • the upper carriage U includes two main roll- shaped pulleys 16 and 18 ( Figures 2 and 5) around which the casting belt 12 is revolved as indicated by the arrows.
  • the pulley 16 near the input end of the machine 10 is referred to as the upstream pulley or nip pulley and the other pulley 18 is called the downstream or tension pulley.
  • the lower carriage L includes main upstream (or nip) and downstream roll-like pulleys 20 and 22, respectively, around which the lower casting belt 14 is revolved.
  • the upstream or nip pulleys 16 and 20 or both the upper and lower carriages are jointly driven through universal-coupling-connected drive shafts 24 and 25 by a mechanically synchronized drive 26 driven by an electric motor (not shown).
  • the frame 19 (Fig. 1) of the upper carriage assembly U is supported on the frame 21 of the lower carriage assembly L through gauge spacers 17 positioned along the length of the casting region on either side, and the precise thickness of these gauge spacers establishes the mold thickness dimension between.the opposed casting faces of the casting belts 12 and 14 and correspondingly the resulting thickness of the cast metal product.
  • Two edge dams 28 (only one of which is seen in Figure 2) are interposed between the opposed casting faces of the casting belts and are guided. Each edge dam is laterally constrained to establish the cast metal width at the nip or upstream end of the casting machine by an edge dam guide assembly 30.
  • edge dams are driven through frictional contact with the casting belts 12 and 14.
  • the two opposed inner casting faces of these edge dams, together with the two opposed casting faces of the upper and lower casting belts 12 and 14 form four moving casting faces of a moving mold in the casting region C having a generally rectangular cross sectional configuration as seen in Fig. 3.
  • the upper and lower carriages U and L are slightly inclined with respect to horizontal so that the casting region C slopes slightly downwardly from the upstream end 11 of the machine 10 to the downstream or exit end 31.
  • the downward inclination "A" is less than 20° from horizontal, and it can be adjusted by means of the jack mechanism 29.
  • Casting belts 12 and 14 are relatively thin metal belts, for example, of steel which require back-up support and an enormous amount of cooling in order to be able to handle the head liberated by the solidifying metal in the casting region C. It is desirable to maintain the casting belts 12 and 14 in intimate contact with the cast metal as it solidifies in the casting region, for avoiding air spaces or gaps between the surfaces of the solidifying metal and the casting belts 12 and 14, for reasons as discussed above in the background section. Among the problem is that the metal shrinks as it solidifies. Furthermore, such shrinkage varies somewhat in different areas of the casting region C. The molten metal is initially fed in between the casting belts 12 and 14 from a tundish 32 (Fig. 2) at the upstream end 11 of the casting region C.
  • the molten metal in the downwardly inclined casting region pushes outwardly, i.e., upwardly and downwardly, against the belts due to metalostatic "head” pressure. As it continues downstream in the casting region this "head” pressure increases. Even after a thin shell of cast metal forms around the molten core the head continues to increase, pressing this shell forcefully outward. Then, as the shell thickens and the molten core begins to solidify, the head ceases its outward pressure and thereafter shrinkage of the solidifying product becomes progressively greater in the downstream portions of the casting ' region.
  • the shrinkage tends to take place away from the upper belt 12, because the weight of the cast product rests upon the lower belt 14.
  • the conductive transfer of heat from the solidifying metal into the lower belt tends to be more uniform than the transfer of heat into the upper belt in the downstream portions of the casting region.
  • the upper belt is locally separated from the upper surface of the solidifying product there is no heat transferred by conduction and a radiant or convective heat transfer occurs. Any separation gaps or spaces between areas of the solidifying metal surface being cast and the belts to which coolant is applied creates hot spots and non-uniform heat transfer which result in crystallographic degradations, segregations, porosity, and imperfections in the cast product as discussed in the background section above.
  • the upper and lower belts 12 and 14, respectively are backed up by a plurality of upper back-up rollers 33 and lower back-up rollers 34, respectively, extending transversely above and below the casting region C.
  • the lower frame 21 in the lower carriage L includes a core section 36 therein, which may be built to be removable as a whole unit.
  • This core section 36 includes a plurality of rigid coolant headers 38 and a frame member 40 by which the lower back-up rollers 34 are supported.
  • the upper carrage U has an upper frame 19 including a similar core section 37 therein which includes a frame member 44 and a plurality of rigid coolant headers 46 which support the upper back-up rollers 33.
  • This core section 37 may be built to be removable as a whole unit.
  • the back-up rollers 33 and 34 had solid shafts 43 and 54, respectively, which were either segmented or continuous. When these shafts were segmented, their ends were mounted in bearings rigidly supported on the stringer members 50 and 54 for being as rigid as possible. The inboard and outward ends of the shafts 43 and 54 were mounted in bearing 56 and 58, respectively, so as to be freely rotatable by the moving belts 12 and 14 as they revolved in the carriages.
  • Back-up rollers 33 and 34 have narrow circumferential ridges or fins 55 which are contacted by the upper and lower belts 12 and 14.
  • the cooling fins 55 provide access around the back-up rollers 32 and 34 so that coolant from the headers 38 and 46 may he applied to and maintained traveling rapidly along the reverse surfaces of the casting belts 12 and 14.
  • the headers 38 and 46 have a series of nozzle openings 60 (Fig. 5) along the length thereof and applicator scoops 61 so that liquid coolant is continuously applied to the belts and maintained traveling rapidly along them.
  • Fig. 5 the casting machine is shown in horizontal position for convenience of illustration, but it is to be understood that the machine actually is inclined downwardly in operation as shown in Fig. 2.
  • Figs. 1 through 5 is of conventional structures which have proven to be advantageous over other types of continuous casting methods and machines.
  • a variety of methods and systems are provided for shaping the casting region in a twin-belt casting machine for improving heat transfer and product uniformity and for enhancing machine performance.
  • the belts will maintain contact with the surfaces of the metal being cast in the casting region in order to provide uninterrupted contact between the belts and the product being cast for providing a predictable heat extraction from the solidifying metal into the belts which is comparable for both the upper and lower belts.
  • the upper back-up rollers 133 are constructed to be flexible for bowing transversely to the casting region C, while the lower back-up rollers 34 are held rigidly in position.
  • the respective roller shafts 63 and 64 both are hollow. Each upper roller shaft 63 is continuous across the full width of the casting region C and is hollow and is constructed with a predetermined bowability.
  • the lower roll shafts 64 are segmented and have internal segmented shafts 66 Figs. 7 and 8 which are supported at the ends of each of their segments by the support members 50.
  • the end-supported-only upper rollers 133 have predetermined bowability and the loading against them is predetermined. Consequently, the bow which will occur in each upper back-up roller at each position along the length of the casting region is predetermined.
  • a convex back-up configuration of a rigidized belt support system in the opposing carriage is provided as shown in Fig. 6.
  • the convex configuration of the rigidized belt back-up system in this opposing carriage, for example in the lower carriage L is predetermined with a convex curvature which will approximately match the predetermined concave curvature of the bowable back-up system.
  • the cast product will generally be cast to a uniform thickness across its width and will have a slight transverse curvature.
  • the compensation for the bulge permitted by the flexible, bowable belt back-up in one carriage is built right into the machine.
  • the desired flexibility and corresponding contoured rigidity may be built into either carriage, but preferably the upper carriage belt back-up is flexible as illustrated in Fig. 6.
  • Such compensation for bulge may be made progressively greater along the direction of casting in the machine, in response to the increasing head of molten metal in that direction and the resulting progressively increasing deflection of the flexible back-up system.
  • this back-up system will not only prevent the occurrence of gaps or insulating air spaces, but the force exerted by the flexible portion of the back-up system will effectively and controllably maintain belt contact and conductive heat transfer and, moreover, render such heat transfer relatively uniform, with corresponding positive results for the progress of the casting.
  • rigid spacers 62 (Fig. 8) of predetermined thickness are mounted between the rigid headers 38 and the intermediate supports 50 for the segmented rollers 34.
  • the adjacent ends of the adjacent sections of the segmented internal shaft 66 are held by the support member 50.
  • One shaft end has a socket 65 which receives the reduced diameter end of the adjacent section of the internal shaft 66.
  • Anti-friction bearings 67 are mounted within the ends of the adjacent sections of the hollow shafts 64 of the lower back-up rollers 34.
  • bearings 67 are retained against an internal shoulder by means of a spacer sleeve 69 held in place by a retaining snap ring 71, and there is a smaller diameter sleeve 73 providing a space 75 for holding grease.
  • a cut-out space 76 in the support 50 permits the socket end of the section of the internal shaft 66 to be removed from the support 50, and similarly in other supports 50 so that the segmented shafts 34 can be individually removed from the carriage and replaced, if desired.
  • the bowability of the end-supported-only, one-piece flexible roller 133 may be greater than the predetermined spring constant value desired, particularly at locations downstream in the machine where the metal "head" pressure is greater. It is not feasible to attempt to decrease their bowability (i.e. increase their spring constant) by increasing their hollow shaft 63 diameter beyond a modest amount, because these back-up rollers are intended to be closely spaced longitudinally along the casting region for appropriately supporting the belt. Too large a shaft diameter would interfere with close roller spacing.
  • external means 98, 100 may be employed.
  • rolling external back-up bearings 98, 100 for each said flexible back-up roller 133 may be placed close to the roller shaft 63 and external to it, said bearings being able to roll against said shaft 63 in the manner of a roller wheel, one per location (see Fig. 9).
  • the resilience of such mounting 100 may be obtained by means of grooves or castellated and bonded rubber sandwich pads, or by Belleville conical spring washers mounted on the mounting bolts for the bracket 99.
  • the external rolling back-up wheels 98 so mounted may or may not touch the shafts 63 of the respective back-up rollers 133 when the machine is empty, depending on the particular application and the downstream position of the particular back-up roller 133.
  • slightly compliant spacers 101 may be mounted between the support members 50 and the rigid lower headers 38.
  • the lower carriage frame 21 and the lower headers 38 and longitudinal stringer members 50 are constructed to be as rigid as practicable.
  • the bowable back-up rollers 133 are connected to the stub-shaft extensions 68 by a pair of axially spaced anti-friction bearings 67 located in a bearing assembly 77 located within a large end portion 79 of the roller 133.
  • the two bearings 67 are axially separated by a spacer sleeve 83 and are mounted upon an inner sleeve 85 on the stub-shaft extensions 68.
  • the space between these sleeves 83 and 85 may be used to hold grease for the two bearings 67.
  • a hardened steel collar or housing 72 seated in a drill hole in the respective carriage frame 19 (or 21 as the case may be) held by a set screw 74 and having an internal shoulder 86 which acts as a fulcrum for the stub-shaft lever 68. Therefore, adjustably moving the outer end of the stub-shaft lever 68 applies a couple-force (i.e. a bending moment) to the flexible back-up roller 133 for bowing it as desired.
  • the fulcrum is actually located at 68, the effective pivot point may be considered to be located at 86A on the axis of the stub-shaft lever.
  • the stub-shaft levers 68 for the upper bowable back-up rollers 133 have actuating levers 78 connected to their outer ends.
  • Each such actuating lever 78 is driven by adjustable means 80 shown as a horizontally positioned tightening machine screw which screws into a socket in the side of the machine frame 19.
  • the stub-shaft lever 68 has a fulcrum 86 provided by a collar or housing 72.
  • the lower back-up rollers 134 are bowable, having self-aligning bearings 59 and fixed stub shafts 70. In the downstream portion of the casting region C where the metal in the casting region C is mostly all solidified, the flexible back-up rollers 134 conform to the thickness of the cast product. Therefore, the adjustment of the adjusting means 80 will tend to establish the arc of transverse curvature of the casting region C and will cause both belts 12 and 14 to hug the product for achieving good and uniform heat transfer over the areas of both top and bottom surfaces of the solidifying product.
  • the back-up-roller-bowing adjustment means 80 therefore are initially adjusted to provide a bow in each successive upper roller 133 which will correspond with the predetermined anticipated bow of the opposed lower roller 134. During operation of the casting machine the operator may then further adjust the adjusting means 80 if desired for further modifying the shape of the casting region C at the location of each adjustable back-up roller 133.
  • the bowing of the adjustable roller 133 may, if desired, be made slightly less than the anticipated predetermined bowing of the lower rollers 134 for providing a transverse contour of the casting region C which is very slightly thicker near the middle as compared with the thickness of the margins near each edge dam 28. This slightly thicker middle then compensates for subsequent shrinkage of the middle of the cast product as it solidifies and cools below its freezing temperature.
  • the back-up roller bowing method and system of Fig. 11 are similar to those shown by Fig. 10, except that the' fulcrum 86 is formed by the juncture of a conically tapered outer section of the stub-shaft lever 68 and a cylindrical inner section of. this stub-shaft lever. Consequently, the hardened steel housing or collar 72 does not include an inner shoulder, and this housing or collar is extended out beyond the side of the frame 19.
  • the adjusting means 81 is a vertically extending machine screw whose shank extends down through a hole in the wall of the cylindrical collar or housing 72. This adjusting screw 81 screws into a threaded hole in the outer end of the conical outer section of the stub-shaft lever 68.
  • the axis of the bowable back-up roll 133 is bowed convexly down toward the casting region C.
  • Figs. 12 and 12A are similar to those of Fig. 11, except that the adjusting means 82 is a longer screw than the screw 81, so that compliance means 84 is included in the adjustment.
  • This compliance 84 is provided by a compression spring which surrounds the screw shank and is compressed between a washer beneath the head of screw 82 and a washer seated on the wall of the cylindrical housing or collar 72.
  • the threaded lower end of the screw shank screws into a threaded hole in the outer end of the conical outer portion of the stub shaft lever 68.
  • the advantages of including this compliance 84 which modifies the adjustment effect of the screw 82 are those resulting from the fact that a smaller gradiant of adjustment is afforded than with the direct (non-compliant) adjustment means shown in Figs. 10 and 11.
  • the compliance of the springs 84 is predetermined to have a range comparable with the bowing compliance of the roller 133 as coupled through (reflected through) the stub-shaft levers 68 to the respective springs 84.
  • somewhat stiffer springs 84 may be employed.
  • compliant means 84 Another advantage of using these compliant means 84 is that they will allow the casting belt 12 to deflect or yield for avoiding damage in case a prematurely solidified chunk of metal passes through the casting region C having a size greater than the spacing between the belts 12 and 14.
  • the fulcrum 86 is provided by the conical/cylindrical junction on the stub-shaft lever 68. In Fig. 12A this fulcrum 86 is provided by an internal shoulder in the collar or housing 72, as previously described. If desired, as shown in Fig. 12A, the threaded lower end of the shank of the screw 82 is extended down through a second hole in the wall of the housing or collar 72, so that an adjustable lock nut 88 may be used to prevent inadvertent "creep" of the adjusted position of the adjusting screw 82.
  • fluid-actuated cylinder and piston units 90 whose piston rods 91 are pivotally connected to the respective outer ends of the stubshaft levers 68.
  • pipe lines 92 for fluid, connected to the upper and lower ends of the cylinder units 90 for operating the piston therein.
  • these units 90 are hydraulic units; however, pneumatic cylinder and piston units 90 may be used, if desired.
  • pneumatic units will inherently provide compliance by virtue of the compressibility of the compressed air in the cylinder 90.
  • check valves are omitted from the pressure regulating valves, which are set at the desired pressure in the cylinder and piston units 90 corresponding to the predetermined desired bowing of the back-up rollers 133.
  • a remote control console (not shown) is located near the operator's station including display meters providing a read-out of the pressure in the control units 90 for each bowable back-up roller.
  • the console display meters may also be calibrated in thousandths of an inch or hundreths of a millimeter for indicating the controlled bowing of the mid-point of the axis of each roller 133 away from a straight line.
  • the pressure in each successive pair of units 90 for each successive bowable roller 133 along the casting region C can be independently controlled, and the resultant amount of deflection of each roller can be read on the read-out displays of the console.
  • the method and system for adjustably bowing the back-up rollers 133 are similar to those shown in Figs. 12 and 12A in that compliance springs 84 are associated with the adjustment screws 82 for bowing the flexible back-up rollers 133.
  • the lower back-up rollers 34 are of rigid three-section construction with longitudinal stringer support members 50 mounted on rigid transverse frame members 38, for example, which may be the coolant headers as explained above.'The upper back-up rollers 133 are being bowed convexly toward the casting region C.
  • the diameter of the middle shaft portion 96 of the hollow bowable roll shaft is made larger than the end shaft portion 94.
  • the diameter of the bore of this hollow roller 133 is uniform. Therefore, the wall thickness of the middle shaft portion 96 is proportionately increased more than the difference in the outside diameter of the middle shaft portion 96 as compared with the outside diameter of the end shaft portions 94. (It is noted that the stiffness of a length of round solid shaft in bending varies as the fourth power of its diameter).
  • the stiffness of the hollow middle portion 96 in bending varies as a higher power function of its outside diameter than in the case of a solid shaft.
  • relatively small increases in outside diameter of the middle portion 96 of this hollow shaft will provide relatively large increases in stiffness as compared with the hollow end portions 94.
  • Fig. 16 the casting region is shown selectively tapered toward the downstream or exit end 31.
  • the casting region is labelled "C or CB" for indicating that this casting region may be relatively wide as illustrated in Figs. 6, 9-15, 17, 20-24 or may be relatively narrower and higher for casting a bar product as illustrated in Figs. 18 and 19.
  • the molten (liquid) metal is indicated dotted at 125, and the solidifed (frozen) metal is indicated by diagonal cross-hatching lines at 135.
  • the cast product P travels away from the caster exit 31 carried by appropriate conveyor means (not shown), and secondary cooling means (not shown) are often employed for further cooling of the cast product P as immediately as possible after exiting from the caster.
  • the molten interior region 125 of the solidifying product 135 continues downstream along a considerable distance approaching toward or even extending beyond the exit 31.
  • This molten interior 125 may be called the molten or "liquid core” or "liquid sump".
  • the faster the caster 10 is running the further downstream extends the interior liquid sump 125.
  • secondary cooling is employed.
  • the casting region C or CB is shown longitudinally divided into an upstream portion or zone 102, a central portion or zone 104, and a downstream portion or zone 106.
  • the rigid back-up rollers 134 and the flexible back-up rollers 133 hold the casting belts 12 and 14 generally parallel.
  • very slight excess (or bulging) in thickness may be provided in the major central transverse area of the casting region C or CB (i.e.
  • the transverse contour of the casting region C or CB may be very slightly thicker over the major central portion of its area) as compared with the margins, because the margins of the cast metal 135 adjacent to the edge dams tend to solidify and cool more quickly than the major central area of the cast metal for thereby compensating for the subsequent shrinkage in this major central area (as seen in transverse section).
  • the belts 12 and 14 begin to converge slightly downstream, i.e. the mold space is tapered by the rigid lower back-up rollers 34 or flexible lower back-up rollers 134 or 108 (Fig. 18) in cooperative action in opposition to the flexible upper rollers 133 or 107 (Fig. 18).
  • the flexible back-up rollers may be bowed, adjusted and controlled in their belt contour configuration in the respective zones 102, 104 and 106 by any one or more (singly or jointly) of the various methods and systems as described above, or as described hereinafter.
  • the longitudinal taper through the various zones 102, 104, 106 may be varied and may be utilized for achieving various transverse contours as desired for causing both belts to hug the solidifying metal 135 and for producing a cast product P of the desired dimensions and desired uniform metallurgical properties.
  • the belts 12 and 14 converge with an increased taper as compared with the zone 104 as achieved by the rigid lower rollers 34 or flexible lower rollers 134 or 108 (Fig. 18) in cooperative action in opposition to the flexible upper rollers 133 or 107 (Fig. 18).
  • the "head" pressure effect against the belts may be greatest in the zone 104 or in the zone 106 depending upon such factors as the amount of solidified metal 135 as compared with liquid sump 125, speed of the caster 10, density (weight per unit volume) of the molten metal 125, overall thickness of the product P.
  • the downstream taper of the longitudinal zones 104 and 106 may be accomplished in part by causing the upper carriage U to converge downstream slightly toward the lower carriage by using compliant gauge spacers 121 (Fig. 26) or 128 (Fig. 27) between the side members of the carriage frames 19 and 21 near the exit end 31 in lieu of the rigid gauge spacers 17 (Fig. 1).
  • rigid gauge spacers 17 are used nearthe upstream end 11 and compliant ones 121 or 128 (Figs. 26 or 27) are used near the downstream end 31. Therefore, the downstream end of the upper carriage U may be caused to "float" somewhat upon the "head” pressure of the liquid sump 125 acting against the area of the upper belt.
  • Fig. 17 the remotely controllable fluid-actuated cylinder and piston units 90A are connected between the stub-shaft levers 68 for applying essentially equal and opposite force-couples (bending moments) to the respective opposed bowable lower and upper rollers 134 and 133.
  • the piston rods 91 are detachably pivotally connected to the respective lower stub- shaft levers 68.
  • the circumferential ridges or fins 55 are shown more closely spaced at 55A (Fig. 17) near the margins of the casting region C, thereby providing the operator with the option of positioning the edge dams 28 closer together. It is desired that the fins 55A be relatively close together for firm back-up of the respective belts where the edge dams are located.
  • the closely spaced fins 55B opposite the edge dams 28 have a reduced diameter as compared with the other fins 55 on the same back-up roller opposite the casting region C.
  • These reduced diameter fins 55B allow the larger fins 55 to push the respective belts 12 and 14 inwardly for causing the belts to hug the solidifying shrinking metal at the margins 97 as close to the edge dams as possible.
  • This reduced diameter fin modification of Fig. 17A can be used to advantage in the zone 106 (Fig. 16) and may be used in the zone 104 (Fig. 16) if desired.
  • This reduced diameter fin modification can be used to advantage in conjunction with the increased flexibility of roller end sections 94 (Figs. 14 and 15).
  • Figures 18 and 19 show the casting of a bar product and so the casting region is labeled "CB".
  • the internal liquid sump 125 is shown, and this liquid sump is smaller in Fig. 19, because Fig. 19 is a section taken farther downstream than Fig. 18.
  • the edge dams 28 are shown higher than in previous Figures, because a bar product'is cast relatively thicker.
  • the large end portions 79A (Fig. 19) of the upper and lower bowable back-up rollers 107 and 108 are made smaller in diameter than the normal-sized fins 55.
  • These large end portions 79A may include one or more grooves 123 for allowing coolant to flow along the belt).
  • the resulting belt clearance spaces at the edge dams permit the fins 55 to deflect the belts slightly to hug the shrinking product very effectively for minimizing any shrinkage gap 97 at the margins adjacent to the edge dams 28. Indeed, such reduced-diameter techniques of relief effectively permit roller-bending or taper to be used downstream.
  • Fig. 18 the large end portions 79 are shown to have the same diameter as the fins 55.
  • the shaft housings 72 project inwardly from the side members of the respective carriage frames 19 and 21 and include internal shoulders formed by hardened steel ring inserts.
  • the remotely controllable fluid-actuated cylinder and piston units 90B for bowing the rollers 107 and 108 are pairs of cylinders located on opposite sides of the lower stub-shaft levers 68. In other words, this pair of cylinders straddles the lever 68.
  • These pairs of cylinders are mechanically interconnected by a yoke structure 127 having a hardened steel ring insert 129 forming the outer pivot fulcrum for the lower stub-shaft lever 68.
  • the pairs of piston rods 91 are also interconnected by a yoke structure 137 having a similar ring insert forming the outer pivot fulcrum for the upper stub-shaft lever 68.
  • the advantage of straddling the stub-shaft lever 68 is that longer cylinder units 90B can be employed more conveniently for a greater range of cast thicknesses.
  • the advantage of the modified design with its greater leverage and heavier parts is that it permits more effective roller-bending for narrow cast products. Equal and essentially opposite force-couples (bending moments) are advantageously being applied to both the upper and lower rollers 107 and 108 for achieving symmetrical upper and lower belt contours.
  • the belt shape and contact control has been primarily accomplished by directly bowing flexible back-up rollers 133, 134, 107, 108 in various ways.
  • Another system which is shown in Fig. 20 involves the elastic bending of a relatively rigid structural frame member 112 having relatively rigid back-up rollers 33 mounted thereto by the stringer members 52, so that these segmented rollers 33 also will be caused to assume an overall arcuate configuration.
  • the transverse frame member 112 which for example may be a header or other frame member, is stiffly bowable. It has upstanding arms 116 at either end.
  • a transverse rod 120 is mounted in the frame 19 of the upper carriage U having tightening nuts 115 on threaded end regions of this rod. In this embodiment by tightening the nuts 115, the frame member 112 is bowed and since the back-up rollers 33 are slaved to this frame member, the back-up rollers 33 also bow a corresponding amount.
  • the lower back-up rollers 134 are bowable under the pressure of the metal "head".
  • a transverse member is positioned generally parallel with the stiffly flexible frame member 112.
  • This second member 110 is more flexible than the first member 112, for example, it is a bowable leaf spring member.
  • This second member 110 is attached by bolts 119 to the ends of the first member 112 with a center spacer or block 114 positioned therebetween. By tightening the bolts 119 at the ends of the bowable leaf spring member, the first member 112 is bowed as is the segmented upper back-up roller 33 which is rigidly attached to the latter by the stringer members 52.
  • this second member 110 which has more flexibility than the first member 112, a finer, more determinate, vernier bowing adjustment can be made of the transverse frame member 112 and hence more determinate bowing of the configuration of the back-up roller 33.
  • a remotely controllable fluid-actuated cylinder and piston unit 117 is pivotally connected at 139 to a bracket 109 mounted centrally on a lower stiffly flexible transverse frame member 112, for example, which may or may not be a coolant header.
  • a remotely controllable bending moment is applied for bowing this transverse frame member 112 whose ends are captured by flanges at 113 and retainers 141 bolted to the lower frame 21.
  • the segmented, rigidly mounted back-up roller 34 is correspondingly bowed to urge the lower belt 14 against the cast metal.
  • the upper back-up roller 133 is bowable, so that the upper belt 12 stays in contact with the top surface of the cast metal.
  • a combination of the transverse frame bowing methods and systems utilized in Figs. 21 and 22 is employed. Accordingly, the upper back-up roller 133 is bowable.
  • the lower segmented back-up roller 34 which is rigidly mounted to the lower frame member 112 is also bowed by actuating the centrally located cylinder unit 117 which is secured by mounting means 143, for example bolts, upon a second, generally parallel, more flexible transverse member 110, for example, a leaf spring member, whose ends are also captured by the retainers 141.
  • the remotely controllable unit 117 is drawing a bow by pushing up on the stiffly flexible member 112 while pulling down upon the relatively more flexible second member 110. Therefore, the remotely controllable unit 117 in Fig. 23 provides an accurately determinate bowing of the first frame member 112 or precisely controlling the configuration of the roller 34 which is rigidly slaved to the member 112.
  • Fig. 24 shows a method and system for controllably bowing rollers 34 generally similar to Fig. 23, except that a pair of remotely-controllable fluid-actuated units 118 mounted on the lower carriage frame 21 are pivotally connected at 111 to the respective ends of the second member 110.
  • a spacer block 114 is located between the central regions of the first and second members 112 and 110, respectively.
  • rocker arm 136 In order to simultaneously bow a plurality of transverse frame members 140 for example, headers, there is a longitudinally positioned rocker arm 136 whose upstream end is effectively pivoted at 142 by a fulcrum connection to the frame 19 of the upper carriage U.
  • a remotely controllable fluid-actuated cylinder and piston unit 138 is secured to the frame 19 in the vicinity of the downstream end of this rocker arm 136.
  • the rocker arm 136 and the cylinder unit 138 are located midway between the inboard and outboard sides of the upper carriage U.
  • Each successive transverse frame member 140 is bowed slightly more than its upstream member, because each successive frame member 140 is being acted upon by the rocker arm 136 further downstream from its pivot fulcrum.
  • a remotely controllable taper of the casting region C is advantageously provided by actuating the unit 138 acting through the rocker arm 136.
  • the compliant gauge spacer 121 (Fig. 26) includes a head 122, a locating pin 124 which engages in a socket 144 in the side frame member of the lower carriage 21.
  • This locating pin 124 is screwed into the head 122 with a plurality of Belleville washers (conical spring washers) 126 on the shank of this pin. These spring washers are captured by a shoulder 146 on the locating pin 124.
  • the lower surface of the head 122 has a concave conical shape 148 with a pitch or slope which is more shallow than the pitch or slope of these spring washers when they are in their unloaded (relaxed) condition, and thus there is a gap 131 for permitting compliant deflection of these spring washers up to a limit when this gap 131 is closed.
  • the slope of concave surface 148 acts as a stop for limiting the deflection of these spring washers to a predetermined limit.
  • the compliant gauge spacer 128 (Fig. 27) has a head 122 and a locating pin 124 inserted into a socket 144.
  • the locating pin 124 is fastened by a small diameter stud 130 passing through a small diameter hole 150.
  • a stiffly flexible leaf spring 152 is thereby captured on the stud 130. The deflection of this leaf spring 152 is limited by the gap at 132.
  • a retainer pin 154 seated in a socket in the side frame 21 engages in a notch 156 for holding this leaf spring in longitudinal alignment with this side frame.
  • bearing assemblies 77 (Fig. 12A) can be inverted (turned inside out) by using hollow cylindrical stub shafts which encircle the bearings 67 which, in turn, encircle the end of the roller shaft 63.
  • transverse members 38 and 46 can be other members than headers.
  • Method and system are provided for continuously casting metal product directly from molten metal in which the molten metal is confined and solidified in a casting region defined above and below by upper and lower, c,ooled, endless, flexible, traveling, casting belts supported by belt support systems including back-up rollers in respective upper and lower belt carriages and laterally defined by first and second traveling side dams, in which the back-up rollers and belt support systems shape and maintain the casting region for improved heat transfer and improved product uniformity and enhanced machine performance.
  • Contact between the casting belts and the cast product is maintained at an acceptable pressure, and the cast product is produced with substantially uniform transverse cross section.
  • Methods and systems including bowing the upper back-up rollers down either by manual adjustment or remote control and at the same time allowing the lower rollers to yield; intentionally rigidizing the upper and/or lower back-up rollers or sections thereof; bowing both sets of back-up rollers in equal and opposite directions, bowing the rollers inward or outward using either manual adjustment or remote control tensioning of these rollers; bending structural frame members which are in support relationship with the rollers and thus maintaining predetermined configurations of the rollers in contact with the belts and further including downstream tapering of the casting region while also employing any of the shape and contact control methods and systems described above.
EP82111600A 1981-12-14 1982-12-14 Method and apparatus for shaping the casting region in a twin-belt continuous casting machine Expired EP0081848B1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US33072781A 1981-12-14 1981-12-14
US33072681A 1981-12-14 1981-12-14
US330727 1981-12-14
US330726 1981-12-14

Publications (3)

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EP0081848A2 EP0081848A2 (en) 1983-06-22
EP0081848A3 EP0081848A3 (en) 1983-08-17
EP0081848B1 true EP0081848B1 (en) 1986-02-26

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ID=26987416

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Application Number Title Priority Date Filing Date
EP82111600A Expired EP0081848B1 (en) 1981-12-14 1982-12-14 Method and apparatus for shaping the casting region in a twin-belt continuous casting machine

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EP (1) EP0081848B1 (no)
AU (1) AU555258B2 (no)
BR (1) BR8207225A (no)
CA (1) CA1192373A (no)
DE (1) DE3269518D1 (no)
ES (1) ES518190A0 (no)
NO (1) NO157489C (no)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4614218A (en) * 1983-03-04 1986-09-30 Electric Power Research Institute Vacuum belt hugger for casting of ribbon
WO1997047414A2 (de) * 1996-06-07 1997-12-18 Salzgitter Ag Bandgiesseinrichtung
FR2775916A1 (fr) * 1998-03-13 1999-09-17 Pechiney Rhenalu Procede et dispositif de controle du profil d'epaisseur d'une bande metallique mince obtenue par coulee continue entre moules mobiles

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8561880B2 (en) * 2012-02-11 2013-10-22 International Business Machines Corporation Forming metal preforms and metal balls

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2640235A (en) * 1949-06-02 1953-06-02 Clarence W Hazelett Metal manufacturing apparatus
US3339625A (en) * 1965-01-28 1967-09-05 Armco Steel Corp Continuous casting apparatus having bent-edge belts

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4614218A (en) * 1983-03-04 1986-09-30 Electric Power Research Institute Vacuum belt hugger for casting of ribbon
WO1997047414A2 (de) * 1996-06-07 1997-12-18 Salzgitter Ag Bandgiesseinrichtung
FR2775916A1 (fr) * 1998-03-13 1999-09-17 Pechiney Rhenalu Procede et dispositif de controle du profil d'epaisseur d'une bande metallique mince obtenue par coulee continue entre moules mobiles
WO1999047293A1 (fr) * 1998-03-13 1999-09-23 Pechiney Rhenalu Procede et dispositif de controle du profil d'epaisseur d'une bande metallique mince obtenue par coulee continue entre moules mobiles

Also Published As

Publication number Publication date
EP0081848A2 (en) 1983-06-22
ES8400903A1 (es) 1983-12-01
BR8207225A (pt) 1983-10-18
NO157489B (no) 1987-12-21
NO824188L (no) 1983-06-15
AU9148182A (en) 1983-06-23
AU555258B2 (en) 1986-09-18
DE3269518D1 (en) 1986-04-03
CA1192373A (en) 1985-08-27
ES518190A0 (es) 1983-12-01
EP0081848A3 (en) 1983-08-17
NO157489C (no) 1988-03-30

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