RELATED APPLICATIONS

This application is a counterpart of U.S. Application Serial No. 08/465,856 which is a continuation- in-part of U.S. Patent Application Serial No. 08/272,678.

FIELD OF THE INVENTION

This invention relates to stationary molds for use with twin-roll casters.

BACKGROUND; PRIOR ART

There may be provided for the casting of a relatively thin steel strip, a twin-roll caster. The concept of a twin-roll caster is about a century old; variants of such casters have received attention recently for the casting of very thin steel strip not intended to be further reduced from the as-cast thickness. In a twin-roll caster, a pair of horizontally disposed casting rolls of adequately large diameter are aligned and rotatably mounted parallel to one another with a slight gap between the two rolls whose width is approximately equal to the thickness of the casting to be made. The rolls rotate in opposite senses downwardly toward the narrowest part of the gap, referred to as the "kissing point". Viewed end on, the left roll rotates clockwise and the right roll counterclockwise. Molten steel is supplied from the tundish to form a pool just above the gap between the two rolls. The molten steel solidifies as it passes towards and through the gap between the two rolls, and exits as a solid strand having a thickness predetermined by the gap between the two casting rolls.

Such twin-roll casters are illustrated and described, for example, in Japanese published patent specification 62-77151 dated 9 April 1987, Japanese published patent specification 1-249246 dated 4 October 1989, and Japanese published patent specification 3-90261 dated 16 April 1991.

Conventionally, in twin-roll casters such as the foregoing, only the twin casting rolls themselves constitute the means for defining the dimensions and particularly the thickness of the cast strand, and constitute the only means for cooling the molten steel sufficiently that it is sufficiently solid to avoid break-outs. However, this conventional arrangement permits the molten steel to be cooled only over a relatively short arcuate segment of the periphery of the twin casting rolls with which the solidifying steel comes into contact. Conventionally, downstream of the twin casting rolls, no further special cooling arrangement is provided; consequently, cooling is less rapid; furthermore, the cast strand must be solid as it leaves the twin casting rolls, and this means that the cooling imparted by the twin casting rolls is critical. Obviously, the greater the speed of longitudinal travel of the cast steel strand, the more acute the foregoing problem. This limited contact of the cast strands with the available cooling surface of the twin casting rolls can, if higher casting speeds or thicker cast strands are attempted, lead to thinner shells, and to attendant increased risk of break¬ outs. Furthermore, the absence of downstream hard reduction implies the absence of preferred dimensional, surface and metallurgical quality of the coiled strip produced from such castings. In a conventional twin-roll caster, the upper limit on the gap between the twin casting rolls, that determines the thickness of the cast strand, is relatively small - typically of the order of about 1 to 5 mm - if the

gap is made larger, the steel strand tends not to retain its shape, and break-outs can occur.

The advantage of conventional twin-roll casters has always appeared to be that they could cast steel of a dimension that is very small compared to the dimensions of conventional castings that are prepared using an oscillating mold of relatively large rectangular open area. Casting the steel in a thinner dimension using twin-roll casters has the advantage for some grades of steel of eliminating or minimizing the need for reduction rolling downstream of the caster, albeit with some loss of surface finish and less than optimum metallurgical quality, but with the benefit that much lower capital is required to build a steel-making facility than would be required for a conventional slab- casting and rolling mill.

SUMMARY OF THE INVENTION

I have discovered that twin-roll casting may be used to produce cast strands of a greater thickness range than is normal for twin-roll cast strands, that have extended metallurgical length which will allow the solidification of the strand to be continued at the twin- roll caster exit such that it retains its shape without break-out, and that in combination with suitable downstream reduction using an in-line hot rolling process, can produce a finished product of superior quality relative to the product conventionally produced by twin-roll casters.

To achieve the foregoing objectives, according to an aspect of my invention more particularly described and claimed in copending U.S. patent application Serial No. , filed on , I provide a twin-roll caster which in its simplest version is of conventional design except that the gap between the twin casting rolls at the

kissing point can be varied over a wider range than is usual in conventional twin-roll casting processes. The gap may be, for example, as wide as about 40 to 50 mm or as narrow as about 3 mm, but is preferably selected to be within the range about 5 to about 35 mm.

Immediately downstream of the twin rolls, I provide a stationary mold having a central vertical channel of rectangular cross-section through which the cast strand passes. At the point of entry of the casting into the stationary mold channel, it may lack dimensional stability and may lack sufficient shell strength that it can successfully avoid break-out of molten steel from the casting. However, the shell, in the course of passing through the stationary mold, is cooled sufficiently that the strand becomes wholly or partially solid throughout; dimensional stability is ensured by the conformation of the shell to the interior cooling faces defining the channel.

This stationary mold in a preferred embodiment is a water-cooled mold having copper cooling faces defining the central open channel structure of the mold. I use the term

"copper mold" herein to mean a copper-faced mold. The mold can be of a design essentially similar to that of conventional oscillating copper molds used in slab casters, except that the upper surfaces of my copper mold are preferably concave-shaped to mate with (but spaced from) the adjacent generally cylindrical surfaces of the twin casting rolls so that the stationary copper mold may be placed in close proximity to the twin casting rolls and immediately underneath them. The stationary copper mold is preferably provided with interior water channels of the general type used in conventional oscillating copper molds, and to be more specifically described below.

A number of variants of my stationary mold design are suitable for different casting thicknesses and casting speeds. These are described in detail below and are claimed in various of the accompanying claims.

By arranging the equipment and the processing procedure in the foregoing fashion, I am able to obtain the thin casting benefit of twin-roll casting, whilst also obtaining the benefit of dimensional uniformity and surface finish of the casting that is typical of the product of larger oscillating mold casters. Further, because such casting may be reduced by downstream reduction in thickness at least twice and preferably three or more times before being down-coiled for shipment, the metallurgical properties of the steel strip thus produced are quite superior to those obtainable from a conventional twin-roll casting facility.

My invention is particularly suitable for the manufacture of steel strip made of any of the following: carbon steel, stainless steel, high-strength low alloy (HSLA) steel, and drawing-quality steel.

SUMMARY OF THE DRAWINGS

Figure 1 is a schematic elevation view, partly in section, of a preferred embodiment of the twin-roll caster, stationary mold, tundish arrangement and downstream rolling line embodying aspects of my invention more particularly described and claimed in my aforementioned U.S. patent application Serial No.

Figure 2 is a schematic end elevation view, partly in section, of a preferred embodiment of the primary and secondary tundishes, twin rolls and stationary mold of the caster of Figure 1.

Figure 3 is a schematic detailed isometric view of the elements of Figure 2. In Figures 1-3, the stationary mold according to my invention is illustrated in simplified schematic manner.

Figure 4 is an isometric schematic view of a twin- roll caster in conjunction with a variant of a stationary mold in accordance with my invention in which the stationary mold design is for use primarily with thicker cast strands or lower casting speeds, and for that purpose includes an adjustable end-piece.

Figure 5 is a schematic plan view of the stationary mold of Figure 4 showing the gap-closing end- pieces at the ends of the gap between the stationary mold faces more closely spaced than is illustrated in Figure 4, so as to provide a narrower cast strand than would be cast by the stationary mold as it appears in Figure 4.

Figure 6 is a schematic isometric view of a twin- roll caster in combination with a second variant of a stationary mold according to my invention provided with an end water spray unit instead of an end wall suitable for use with thinner castings or higher casting speeds.

Figure 7 is a schematic isometric view of the stationary mold of Figure 6.

Figure 8 is a schematic isometric view of an alternative embodiment of a stationary mold according to my invention, provided with an end spray unit at the end of the gap between the mold faces and suitable for use with thinner mold castings or for high carbon steel castings within the casting thickness range for which my invention is suitable.

Figure 9 is a partially exploded schematic view, illustrating the cooling channel arrangement for half a stationary mold of the type generally illustrated in Figure 8.

Figure 10 is a schematic end section view of the outer segment of half the stationary mold of Figure 9, illustrating the internal structural reinforcing elements.

Figure 11 is a schematic end view of the outer portion of one-half of a stationary mold of the type illustrated in Figure 9.

Figure 12 is a schematic side elevation section view of the mold portion of Figure 11 taken along the line 12-12 appearing in Figure 11.

Figure 13 is a schematic end elevation section view of the portion of the half mold of Figure 11 taken along the line 13-13 of Figure 12.

Figure 14 is a front elevation view of the inner (right-hand) segment of the half mold of Figure 9 showing the water channelling arrangement appearing on the interior face of that portion of the half mold.

Figure 15 is a schematic plan section view of the segment of the mold illustrated in Figure 14 taken along the line 15-15.

Figure 16 is an end elevation section view of the segment of the mold illustrated in Figure 14 taken along the line 16-16 in Figure 14.

Figure 17 illustrates schematically in partially exploded view an alternative half mold structure generally

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similar to that of Figure 8, in which the exit port for the water channelling is varied as compared to that of Figure 9.

Figure 18 is a schematic partly exploded view of half a stationary mold constructed according to the principles of my invention differing from that of Figure 9 in that the upper-most portion of the mold face is bevelled or angled at the mouth of the mold gap.

Figure 19 is a schematic end elevation section view of the half mold of Figure 18.

Figure 20 is a schematic exploded view of an end gap closure element forming a portion of the variant of the stationary mold illustrated in Figure 4.

Figure 21 is a schematic side elevation section view of the gap closure element of Figure 20.

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

Referring to Figures 1-3, molten steel is supplied from a primary tundish 1 to a secondary tundish 3 and thence via a guiding shroud 4 to form a pool of molten steel 53 just above the gap 55 formed between a pair of parallel horizontally aligned casting rolls 57, 59 rotating in opposite senses, the roll 57 rotating clockwise, and the roll 59 counterclockwise, as seen in the drawings. Framework, bearings, mountings, etc. are omitted from the drawings for the purposes of clarity and simplicity.

The casting rolls 57 and 59 of the twin-roll caster, referred to generally by reference numeral 7, have copper peripheral cylindrical surfaces. Twin-roll casters are well-known in the industry; a useful review can be found in the paper by Kasama et al . , "Twin Drum Casting Process

for Stainless Steel Strand", Proceedings of SNRC-90 Conference, 14-19 October 1990, Pohang, Korea, held by The Korean Institute of Metals and The Institute of Metals, UK, at pp. 643-652. See also Cramb, "New Steel Casting Process for Thin Slab and Strand: A Historical Perspective", Iron and Steelmaker Vol. 20 No. 7, 1988, pp. 45-68. Such twin- roll casters preferably have slightly concave crown profiles in conformity with preferred practice so as to give the cast strand a slight convex profile (positive strand crown profile) . The convex profile is desirable for uniform deformation of the hot strand during subsequent hot rolling reduction (see, e.g. Chiang, "Development and Application of Pass Design Models at IPSCO's Steckel Hot Strand Mill" (1992), 33rd MWSP Conference Proceedings, ISS-AIME, Vol. 29. The rolls 57, 59 may be kept within profile specifications by on-line peripheral roll grinders 8 of conventional design, lubricated by lubricant injectors 6, and preheated by hot-air heaters 25 before reaching the pool of molten steel 53.

The twin-roll caster 7 is used to cast a strand ranging from about 5 mm to about 35 mm in thickness, or, less economically, sized outside these preferred dimensions to a lower limit of about 3 mm and an upper limit of about 40-50 mm. The casting may preferably be about 900 to about

1800 mm in width, or somewhat outside these dimensions.

This as-cast strand is subsequently processed by in-line hot rolling stands (to be described below) to achieve finished strand thickness ranging from about 1.5 mm to about 12 mm, assuming the conventional 3-to-l reduction of the initial casting. The speed of rotation of the casting rolls 57, 59 is selected to range from about 1.5 rpm to about 12 rpm, the latter for castings of about 5 mm thickness and the former for castings of about 35 mm thickness. Cooling water flow through the rolls 57, 59 is set at about 500 GPM to 1000 GPM per roll to provide optimum cooling effect for good strand

surface quality, and is adjusted according to the thickness of the casting.

A guiding shroud 4 of rectangular cross-section fixed to the underside of the secondary tundish 3 and communicating with the exit port 51 of the secondary tundish 3 guides the flow of steel into the pool of molten steel 53 formed immediately above the gap 55 between twin casting rolls 57 and 59. The guiding shroud 4 tends to isolate the incoming steel from ambient oxygen. Inert gas or a reducing gas or a combination of both is injected above the pool 53 to prevent oxygen from gaining access to the surface of the molten steel pool 53.

Located between the ends of the twin casting rolls

57, 59 are side dams 83 whose concave arcuate sides 85, 87 conform in shape and radial and axial dimension to the cylindrical peripheries of the rolls 57, 59. The side dams 83 serve to confine the ends of the steel pool 53. The dams 83 are preferably made of high-temperature-resistant refractory material. The top edge 89 of each of the dams 83 must be above the level of the meniscus of the steel pool 53 sufficiently to prevent any overflow, and should extend as close as feasible to the splash guard 5 so as to minimize the loss of the inert gas atmosphere. The bottom edge 91 should extend below the kissing-point gap 55 to just above the top edges of the stationary mold 10, so as to minimize the risk of any break-out between the dam 83 and the stationary mold 10. The dams 83 are designed to be movable transversely in either direction. They are illustrated in Figure 3 at the outer limit of their possible transverse movement; they may move inwardly from their positions at the ends of the rolls 57, 59 to reduce the width of the cast strand. Means (not shown) , such as a suitable conventional hydraulic piston/cylinder arrangement, may be provided to

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adjust the spacing between the dams 83 to accommodate varying widths of strand.

_t . As the molten steel passes from the top of pool 53

5 to the gap 55, it begins to solidify. If the gap 55 is very narrow, say less than about 5 mm, the steel may be completely solidified at or shortly below the kissing point between rolls 57, 59. However, at wider gap dimensions, the still hot, liquid core of the steel as it emerges downstream 10 of the gap 55 will not permit the strand reliably to retain its shape; the risk of break-out would be high. This fact has limited the use of conventional twin-roll casters to cast strand thicknesses of less than about 5 mm.

15 According to the present invention, positioned immediately downstream and underneath of the rolls 57 and 59 is a stationary mold 10 having a central channel 65 of rectangular cross-section whose narrow dimension is approximately equal to or very slightly smaller than the

20 dimension of the gap 55 between the twin casting rolls 57 and 59. The width of the channel 65 may taper very slightly inwardly from top to bottom to accommodate thermal contraction and solidification shrinkage of the steel strand as it solidifies; the gap width may receive fine adjustment

25 by machining the surfaces of the stationary copper mold 10.

The stationary mold 10 is preferably a water- cooled copper mold, i.e. its faces forming the interior channel 65 are formed of copper; the balance of the mold

30 structure may be made of steel. The mold 10 is shaped so that its upper concave surfaces 69 lie as close as possible to the casting rolls 57 and 59 above, and in particular so that the entry mouth 67 of the mold channel 65 is as close as possible to the kissing-point 55 between the casting

^* 35 rolls 57 and 59. The flow of mold cooling water through the mold 10 may be adjusted so that heat flux extraction in the

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range of about 5 to about 30 cal/cm ² /sec is obtained. This range should be satisfactory for the range of casting thicknesses for which the equipment is designed.

For the casting of very thin strands, the stationary mold 10 may not be necessary. If the strand is solid as it leaves the twin casting rolls 57, 59, there is no need for the stationary mold 10, which can be removed and/or by-passed. The stationary mold according to the invention finds its utility primarily for strands of at least about 5 mm in thickness.

Cooling of the molten steel occurs over that portion of the peripheral cylindrical surface of each of the rolls 57, 59 subtended by angle A (Figure 2) , and by the interior vertical faces 73 of the stationary mold 10. Further cooling occurs in a strand containment and secondary spray cooling station 11, to be further described below.

It can be seen from the drawing that the vertical faces 73 of the stationary mold provide a cooling area that is about equal to the cooling area provided by the cylindrical surface subtended by angle A of each of the twin casting rolls 57, 59. However, the ratio of cooling surface area of stationary mold to twin-roll caster cooling surface area, and the ratio of both to the strand containment cooling area to be described further .below, may vary considerably according to the designer's preference. In any case, the additional provision of the stationary mold to the layout can substantially increase the available primary cooling area for the molten steel being cast, as compared with conventional twin-roll caster design. This enables much wider gaps 55, 65 to be present between the twin rolls 57, 59 and the two opposed cooling blocks 64, 66 of the stationary caster 10 than is possible using conventional design.

While reference herein is made to the mold 10 as being a "stationary" mold, it is to be understood that the two opposed cooling blocks 64, 66 of the stationary mold 10 can, in fact, be moved towards and away from one another to 5 accommodate varying thicknesses of casting. The same, of course, is true for the twin rolls 57 and 59; the gap 55 may be adjusted according to the casting thickness desired. Although, as mentioned, the apparatus according to the invention can be used for making castings with a thickness 0 as thin as about 5 mm, some of the principal advantages of the invention are most markedly obtained when the thickness of the casting is relatively large, in about the 35 mm range.

5 Immediately downstream of the stationary water- cooled copper mold 10 is a strand containment stage 11 comprising opposed pairs of horizontally rotatably mounted segmented rolls 29, one in each pair on either side of the casting 31 emanating from the mold 10. These rolls 29 are 0 aligned with the exit port from the stationary mold 10 and

_*

' provide an opportunity for further cooling of the casting 31 before it reaches preferred reduction rolling temperature. The strand containment stage 11 may, for example, comprise 8 pairs of segmented rolls 29 located immediately below the 5 extended water-cooled copper mold 10. Such segmented rolls are of the same general type as used in conjunction with conventional oscillating slab casters.

The strand containment station 11 along with the 0 cooling surfaces of the stationary water-cooled mold 10 provide an effective metallurgical length (from the kissing point of the twin casting rolls 57, 59) of about 2100 mm for strand cast at 35 mm thickness. Equipment so designed will allow a calculated casting speed up to about 8 to 9 m/min 5 for cast strand 35 mm thick and up to about 1 m/sec for strand 5 mm thick.

Further details of the strand containment apparatus 11, strand redirection station 13, downstream reduction stations 15, 19, 21 and associated downstream equipment may be had by reviewing my copending U.S. patent application Serial No. , filed on

The stationary mold 10 has been presented in a very simplified schematic fashion in Figures 1, 2 and 3. A somewhat more elaborate schematic depiction of a variant of stationary mold 10 appears in Figure 4. The mold 10 may take a variety of specific forms as will be described further in this specification.

The variant of the mold 10 illustrated in Figure 4 is particularly suitable for use with cast strands of relatively large thickness (toward the upper end of the 35-

50 mm range) and particularly such castings that are moving relatively slowly. This particular variant of the stationary mold 10 is provided with opposed adjustable end- closure walls 45 each of which is water-cooled by means of an interior cooling duct arrangement (see Figures 20 and 21 and associated description below) via water conduits 195 and

203. Conduit 195 serves as an entry conduit and conduit 203 serves as an exit conduit for the cooling water supply to the interior of end piece 45.

While Figure 4 illustrates the end pieces 45 at their maximum separation (to accommodate the largest width of strand that the caster is designed to cast) , Figure 5 illustrates the end pieces 45 spaced more closely together to accommodate a somewhat narrower width of casting. Obviously the end pieces 45 in the stationary mold would move in tandem with the dams 83 for the pool of molten steel 53, thereby conforming the strand width cooled by the stationary mold to that initially cast by the twin-roll caster 7.

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Note that the stationary mold 10 of Figure 4 is provided with upper bevelled surfaces 103 and lower bevelled surfaces 105 at the upper and lower vertical extremities of the stationary mold gap 65. These surfaces tend to 5 facilitate the passage of the cast steel strand 31 through the stationary mold gap 65, particularly for cast strand of larger thicknesses above about, say, 20 mm. The bevelling renders less sharp the corners of the stationary mold at the entry and exit points for the cast steel strand 31, and 0 consequently less likely to interfere in any way with the smooth passage of the cast steel strand 31 through mold gap 65.

Figure 4 also shows auxiliary cooling spray units 5 107 located at the outer extremities of stationary mold 10 whose nozzles 109 spray cooling water (preferably as a stream of mixed air and water) into the gap between the underside of rolls 57, 59 and the upper concave surfaces 69 of the stationary mold 10. It is important that no surface water remain on twin rolls 57, 59 when they are lubricated

_* and especially when they make contact with the pool of molten steel. Hot-air heaters 25 serve to remove any surface water from the twin rolls 57, 59.

Figure 6 illustrates an alternative structure of the stationary mold 10 in which no end-piece 45 is provided. Instead, the gap 65 between the left stationary mold block 111 and the right stationary mold block 113 is open at its ends. Furthermore, at each end of the stationary gap 65, there is provided a cooling spray unit 115 whose array of nozzles 117 provide a steady cooling spray to the side edges of the cast strand passing through the stationary mold gap 65. Again a stream of mixed air and water is preferred. The arrangement of Figure 6 is suitable where the cast strand emanating from the twin-roll caster 7 has sufficient dimensional stability that the risk of breakout

or unacceptable bulging of the strand 31 at its edges is acceptably low. Subject to the foregoing consideration, the water spray units 115 may be used in substitution for gap end-pieces 45 for almost the entirety of the range of cast strand thicknesses for which the present invention is suitable (namely from about 5 mm or somewhat less to 35 to 40 mm or somewhat more) . The water spray intensity may be varied depending upon the thickness of the cast strand passing through the stationary mold gap 65, the intensity increasing with the thickness of the casting. The water spray provided by the spray units 115 tend to suppress temperature rebound within the casting, thereby avoiding the detrimental metallurgical effects associated with temperature rebound.

For sufficiently thin castings, a gap end closure element 45 is almost never required; the use of a water spray unit 115 at each end of the mold gap 65 is preferred.

The stationary mold variant 10 of Figure 6 is illustrated in a complete isometric aspect in Figure 7 apart from the twin-roll caster 7 with which the stationary mold 10 is intended to be used. Note that in Figure 7 it can be clearly seen that both the left hand mold block 111 and the right mold block 113 are subdivided into an outer mold block segment 119, 121, respectively, and an inner mold block segment 123, 125, respectively. The respective structures of the inner and outer mold block segments will be discussed in detail below.

Figure 8 illustrates a further variant of stationary mold 10. This variant resembles that of Figure 7 but differs in that inner mold block segments (designated 123A, 125A, respectively in Figure 7) are provided not with upper bevelled surfaces 103 as shown in Figures 4, 5 and 6 but rather with sharply inclined upper concave surfaces 127

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forming a concave surface continuum with the mating upper concave surface 129 of the adjoining mold block segment 119 or 121, as the case may be. In other words, the pair of

, mating upper concave surfaces 127, 129 together constitute 5 the upper concave surfaces 69 of the stationary molds 10. While such surface pairing exists also in the stationary mold illustrated in Figure 7, it can be seen that upper concave surface 127 in Figure 7 is appreciably narrower than that appearing in Figure 8, the reason being that the

10 surface 127 of Figure 7 has been cut short by the bevelling of the upper portion of the mold block segments 111, 113 to provide bevelled upper surfaces 103 at the tops of mold blocks 111, 113. By contrast, no bevelling occurs in the stationary mold 10 of Figure 8, and the mold faces 131

15 constituting the broad faces of the stationary mold gap 65 (the faces 73 of Figure 2) continue upwards to form a sharply pointed apex 133 with adjoining concave surface 127 at the very peak of the respective mold block segments 111, 113.

20

The variant of stationary mold 10 illustrated in Figure 8 is particularly suitable for thinner cast strands 31 of less than about 20 mm in thickness, and particularly suitable for high-speed casting.

25

Figure 9 illustrates a cooling channel arrangement for the stationary mold 10 of Figure 8. In Figure 9, the two segments 119, 123A forming the left mold block 111 have been opened up to illustrate the interior cooling channel

30 arrangement. The inner mold block segment 123A provides the planar copper cooling face 131; the pair of copper faces 131 of the two mold blocks 111, 113 together define the mold channel 65. It is necessary that heat be removed quickly from the faces 131 so that these faces do not soften and so

35 that they conduct heat rapidly away from the cast steel strand 31 passing therebetween. To this purpose, an array

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of vertical channels 135 arranged in spaced groups 137 carry cooling water that maintains mold block segment 123A at an adequately cool temperature. Water is supplied to the bottom extremities of channels 135 by means of supply slots 139 communicating with the generally hollow interior entry chamber 141 (see Figure 10) of mold block segment 119. Water passing from the interior chamber 141 of mold block segment 119 passes through the slots 139 to the bases of cooling channels 135 and travels upwardly along channels 135 to the tops of the channels 135 whence the water exits via upper exit slots 143, from whence the water passes into exit chamber 145 (Figure 10) within the interior of mold block segment 119, and thence via outlet pipe 153

(Figure 12) to a drain (not shown) .

In a typical installation, channels 135 may be about 5 to 10 mm wide and about 15-35 mm deep.

By referring to Figure 12, it can be seen that the water entry chamber 141 within mold block segment 119 communicates with a water supply pipe 147 provided with a terminal coupling 149 for coupling to an external water supply pipe (not shown) . For simplification of illustration, the supply pipe 147 is not illustrated in Figures 9, 10 and 11; these figures have been prepared as if the portion of pipe 147 extending beyond the end faces 151 of mold block segment 119 were not present.

Exit pipe 153 is provided with a coupling 155 for attachment to an external exit conduit (not shown) . Exit pipe 153 communicates with exit chamber 145 and serves to drain off the heated water emanating from the tops of cooling channels 135 and thence via exit slots 143 to the exit chamber 145 within mold block segment 119.

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The pressure of the supply water entering supply pipe 147 and supply chamber 141 may be varied so that more cooling water flows in the case of thicker castings than would be required to cool the mold when thinner castings are passing through the mold gap 65. The adjustment of water pressure can be effected empirically. Water pressure of the order of 50 to 100 psi is expected to be satisfactory for most applications.

The peak portion of mold block segment 123A will not be effectively cooled by the cooling channels 135.

Accordingly, interconnected interior cooling conduits 157

(see Figures 10 and 16) may be provided in the vicinity of the peak portion 159 of mold block segment 123A in order to provide adequate cooling of this portion of segment 123A. For this purpose, protruding end conduits 161 communicating with the set of interior cooling conduits 157 are provided for coupling connection to suitable delivery and drain conduits (not shown) .

A dividing wall 163 (Figures 10, 12) separates the supply chamber 141 from the exit chamber 145. Structural strength is provided within the interior of mold block segment 119 by means of upper reinforcing elements 165 and lower reinforcing elements 167 spaced from one another across the width of mold segment 119 (Figure 13) . Furthermore, generally horizontal reinforcing bars or bolts 169 (Figure 10) are provided, whose ends 171 may be threaded to engage counterpart threaded blind holes 173 in the inner mold block segments 123A. These bolts 171 pass through holes 175 in the vertical face 177 of mold block segment 119. The holes 175 are located in an array that mates with the array of threaded blind holes 173 in the facing wall 179 that tightly and matingly engages planar wall 177 of mold block segment 119. When the bolts 169 are completely threaded into the blind holes 173, they maintain the two

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opposed faces 177, 179 in tight engagement thereby providing a closure for the vertical cooling channels 135 in the inner mold block segment 123A.

Figure 17 illustrates a mold segment configuration generally similar to that of Figure 9, the principal difference being that each of the connecting pipes 161 functions as an inlet pipe. The outlet for the interior channels 157 at the peak portion 159 of mold block segment 123B is provided by means of a collector conduit within the interior of mold block 123B, whose outlet is illustrated as outlet port 181 in Figure 17. This outlet port 181 mates with a counterpart outlet port 183 in mold segment 119B that communicates with the exit chamber 145 within the interior of mold block segment 119B. The slot 185 immediately underneath aperture 183 acts as a collector for the array of cooling channels 135X located immediately underneath port 181.

Figure 18 illustrates a mold block arrangement generally similar to that of Figure 9, except that the top portion of each of the mold block segments 119C, 123C is bevelled as illustrated in Figure 7, for example, to provide an upper bevelled surface 103 instead of a sharp peak 133 (compare Figure 8, for example) . Otherwise the channel reinforcement and interior arrangement of Figure 9 (as developed in Figures 10 through 15) is generally similar to that of the mold block of Figure 9.

Figure 19 illustrates the modified interior structural arrangement of the mold block half of Figure 18, which arrangement differs from that illustrated in Figure 10 primarily in the omission of transverse cooling channels 157 from the structure of Figure 19 and the inclination of the connecting bolt 169C at the top of the structure illustrated in Figure 19, the inclination serving to provide a more

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effective joinder between the two mating surfaces of the two segments 119C, 123C at the top of the structure.

Figures 20 and 21 illustrate in more detail the structure of a suitable end-piece 45 for closing at each end of the gap 65 between the mold blocks forming stationary mold 10. It can be seen that the end-piece 45 is preferably formed as two discrete component elements 187, 189, component 189 being the inner-most component whose inside copper surface 191 makes cooling contact with the side edges of the steel strand 31 passing through the stationary mold gap 65. Inner end-piece component 189 is cooled by means of vertically extending cooling channels 193. An inlet pipe 195 is coupled to an external supply of cooling water (not shown) and provides a constant flow of water via interior chamber 205 and outlet port 197 to the bases of the cooling channels 193. Water flows up the cooling channels 193 and is collected by an exit port 199 in component 187, which exit port 199 mates with and is opposite the upper extremity of the cooling channels 193 in component 189. Water flows from outlet port 199 through interior conduit 201 within component 187 and thence to an output pipe 203 that may be coupled to a suitable external outlet drain pipe (not shown) .

The width of any given end-piece 45 will of course be fixed but the user of the stationary mold 10 would expect to have on hand a number of end-pieces 45 of varying widths, so that the spacing between the two opposed mold blocks forming the stationary mold could be varied, since the width of the gap 65 should preferably accommodate the thickness of cast strand 31 passing therethrough. It is contemplated that the space in between twin rolls 57 and 59 will be varied to permit the user to manufacture strands of different thicknesses and, consequently, the number of different thicknesses that are expected to be cast would

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require at least the same number of pairs of end-pieces 45 to be available, so that the width of the stationary mold gap 65 could always be accommodated to the width between the casting rolls 57 and 59.

It will be understood that all of the components of Figure 9 through 21 represent the components for use on one side or one end (as the case may be) of the stationary mold 10 and that counterpart elements having essentially a mirror image structure will be provided on the other side or the other end, as the case may be, of the stationary mold ^* 10, as the case may be.

Further variants, modifications and improvements will readily occur to those skilled in the art; the scope of the invention is as defined in the appended claims.