US 3429363 A
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Feb. 25, 196% R. w. HAZELETT ET AL 3,429,363
METHOD OF COOLING THE CASTING BELT IN A CONTINUOUS METAL CASTING MACHINE OF THE DRUM AND BELT TYPE Filed April 14, 1966 Sheet T mm LL mu m A H C WR T R E w Y R B ATTORNEYS.
Feb. 25, 1969 R. w. HAZELETT E A 3,429,363 NUOUS TYPE METHOD OF COOLING THE CASTING BELT IN A CONTI METAL CASTING MACHINE OF THE DRUM AND BELT Filed April 14, 1966 Sheet INVENTOR. ROBERT WILLIAM HAZELETT RICHARD HAZELETT V ATTO/BVEYS.
Filed Apr. 14, 1966, Ser. No. 542,566 US. Cl. 164-87 4 Claims Int. Cl. B2211 11/06, 11/12 ABSTRACT OF THE DISCLOSURE Method of cooling the casting belt in a continuous metal casting machine of the drum and belt type in which the belt is bent into reverse curves so that it does not completely encircle the drum and thus the cast product can be led directly out of the machine. The coolant is flowed longitudinally at high speed along the concave portion of the rear face of the belt as the belt approaches the drum and is flowed transversely thereof at high speed along the convex portion where the belt curves around the drum. There is a transition provided between longitudinal and transverse flow.
The present invention relates to method and apparatus for cooling the belt in a metal casting machine of the drum and belt type. In this type of machine a continuously moving mold space is defined between the periphery of a revolving drum and a belt which runs partially around the drum as the drum revolves. This invention relates to method and apparatus for cooling the casting belt as it a proaches the drum and as it comes into contact with t and as it revolves with the drum to prevent buckling or Warping of the belt and to confine the molten material in the moving mold space without leakage.
In the prior art, for example as shown in United States Patent No. 2,865,067, issued to Properzi, are disclosed arrangements for cooling the drum by flowing liquid coolant through a network of interconnected passages within the drum. However, great difficulty has been experienced for many years in attempts to cool the casting belt. The prior art arrangements tended to cool the drum more efficiently than the belt. This often set up temperature differentials across the material being cast, producing uneven cooling which adversely aifected the cast product. In addition, the flexible casting belt was unevenly cooled, which set up localized stresses in the belt, caused its rapid deterioration and created localized defects in the outer surface of the product being cast. Moreover, there were problems in holding the belt firmly against the drum Without buckling and without warping or allowing the belt to separate from the drum, which would allow leakage of the molten material being cast.
In the Properzi machine the belt runs in an oblong path which completely encircles the drum. This requires that the cast product be bent sideways to clear the belt as the product is led out of the machine. In the improved type of machine as shown in FIGURE 1 herein the belt is bent into reverse curves so that it does not encircle the machine and the cast product 33 can be led directly out of the machine without bending sideways.
These problems of cooling the belt are particularly severe in the drum and belt machines of this type as shown in FIGURE 1 for casting molten metal in which the front face of the belt is curved in one direction as it approaches the drum and then passes through a transition region and curves in the opposite direction as it runs adjacent to the drum for confining the molten atent O metal against the front face of the belt. That is, the belt follows a path including concave and convex curving portions with an intermediate transition region. The molten metal is introduced into the moving mold space between the drum and the front face of the belt near the transition region, and this is the region of greatest temperature which requires very intense cooling of the rear face of the casting belt. At the same time this is the region where the belt is changing its curvature and requires accurate firm guidance and support to prevent buckling 0r warping and to prevent the belt from separating from the drum.
These problems have remained unsolved for many years and have limited the usage of this type of drum and belt machine to the casting of lower melting temperature metals.
Among the advantages provided by the present invention are those resulting from the fact that it enables intense, uniform cooling of the rear face of the casting belt all along near the moving mold space, including the input region where the belt follows a reverse curve. The more effective cooling provided by this invention allows the use of a thinner casting belt which does not deteriorate through distortion due to temperature differential between the front and rear face of the casting belt and therefore the operating life of the cooling 'belt is greatly extended.
In accordance with the cooling method of the present invention in one of its aspects the liquid coolant is impinged against the rear face of the belt near one edge where the rear face follows a convex path around the drum, and the coolant travels transversely across the convex rear face of the belt toward the other edge.
The cooling method of this invention in another of its aspects includes the steps of flowing the coolant longitudinally along a concave portion of the rear face of the belt as it approaches the drum and flowing the coolant transversely of the rear face along the convex portion of the rear space near the drum, and of making a transition from longitudinal flow to transverse flow.
It is the object of this invention to provide method and apparatus for cooling the casting belt in a drum and belt machine radically improving the performance and reliability of these machines to the end that their utilization and fields of application may become greatly widespread for continuous casting of metal.
In this specification and in the accompanying drawings are described and shown method and apparatus embodying the invention for cooling the casting belt in a drum and belt machine for casting metal, and it is to be understood that these are given for purposes of illustrating the best mode currently contemplated for carrying out the invention in order that others skilled in the art may fully understand the invention and the manner of carrying out the invention in order that others skilled in the art may fully understand the invention and the manner of carrying out the invention in practical use and so that they will understand how to utilize equivalents of this method and apparatus as may be best suited to the conditions of various particular continuous casting installations.
The various features, aspects, and advantages of the present invention will become more fully understood from a consideration of the following specification in conjunction with the accompanying drawings, in which:
FIGURE 1 is a side elevational view of a casting machine of the drum and belt type for practising the cooling method of the invention and embodying apparatus of the invention;
FIGURE 2 is an end elevational view of the machine of FIGURE 1 as seen from the direction 2-2 in FIG- URE 1 and drawn on enlarged scale with the belt shown broken away to disclose underlying structure;
FIGURE 3 is a cross sectional view taken along the line 33 in FIGURE 1 in the input region where the molten material is introduced into the moving mold space. In this specification the molten material is shown as metal and the method and apparatus herein are the best mode currently contemplated for carrying out the invention in continuously casting metal;
FIGURE 4 is a cross section taken along the line 4-4 in FIGURE 1 illustrating the cooling method; and
FIGURE 5 is a perspective view illustrating the cooling of concave and convex portions of the rear surface of the belt and also for cooling the intermediate transition or inflection region.
As shown in FIGURES l and 2, the continuous casting machine includes a frame base 12 having a drum 14 rotatably mounted on this base. A flexible casting belt 16 runs in an arcuate path around a portion of the revolving drum and is guided and supported by three pulley wheels 17, 18 and 19. Between the periphery of the revolving drum and the belt is defined a moving mold space 20 (FIGURE 3). This mold space 20 is formed by a peripheral casting groove 22 in the drum 14 with the belt 16 pressing firmly against a pair of lands or rim portions 23 of equal diameter which straddle this groove 22.
As shown in FIGURE 3, the casting belt 16 spans across between the lands 23, and its front face F is toward the mold space, while its rear face R is cooled by fast-travelling liquid coolant 21, for example such as water which is used in this machine. In order to contain the molten material 25 within the mold space 20 and to cast a product of high quality, it is important that the casting belt 16 be held firmly against the lands 23 and that its front face F continue in a smooth curvature adjacent to them, without any warping or localized distortion.
For cooling the drum 14 there is a network of interconnected passages 24 (FIG. 3) to which liquid coolant is supplied under pressure through a hollow drum shaft 26 (FIG. 2). The coolant returning from the passages 24 is received in a chamber 27 provided by a conical end plate 28 and then flows into a return duct 29 to circulate back to a suitable reservoir for holding the coolant.
As shown in FIGURE 1 the molten material 25, is supplied from an insulated pouring container or tundish 30 and feeds down through a spout 31 into the input region or entrance 32 to the mold space 20. This machine is particularly adapted for continuously casting molten metal, such as aluminium, copper or steel. The cast prodnet 33 is led out of the machine at a point which is generally on the opposite side from the entrance 32.
Near the entrance to the mold space, the casting belt 16 runs around the pulley 17, as seen in FIGURE 1. In order to press the belt firmly against the lands 23, the entrance pulley 17 has a pair of support surfaces 36 of equal diameter, each of which is directly opposite one of the lands 23. Thus, the belt 16 and drum 14 are held together about the entrance 32 to prevent leakage of the molten metal. The sectional view of FIGURE 3 is taken directly at the entrance plane where the support surfaces 36 are pressing the respective edge areas of the belt 16 tightly against the lands 23. Also, the belt 16 is maintained under tension pulling it tightly against the drum 14 as it runs therearound.
In following the path described by the belt 16 near the entrance 32 it is seen that the rear face R describes a concave curve as it runs around the pulley 17; then the belt flexes through a reverse curve or line of inflection along a transverse line, which is indicated by dashes at 38 (FIG. 5); and then the belt describes a convex curve as it runs around the drum 14.
For providing an intense cooling of the casting belt 16 adjacent to the input region 32 where i1 6 mol en metal 25 is at its highest temperature, the entrance pulley 17 has a plurality of deep narrow grooves 40, seen most clearly in FIGURE 3. Between these grooves 40 the pulley 17 has thin knife-like fins 42 which provide support for the middle portion of the belt 16 as it runs around the pulley 17 over the grooves 40 to resist the tension force under which it operates. A plurality of long, coolant-feed nozzles 44 curve approximately half way around the pulley 17, and one of these nozzle tubes 44 nests within each groove 40 beneath the concave rear belt surface R, as shown in FIGURES l and 2. The liquid coolant is fed under high pressure through a line 46 into a manifold 47 to which the base end of each of the nozzle tubes 44 is connected. As shown in FIGURE 2, the manifold 47 is adjustably mounted by bolts 48 secured to a bracket 49, which is attached to the bearing support '50 for the shaft of the pulley 17. This adjustment enables the nozzle tubes 44 to be aligned with the grooves 40 when the machine 10 is set up for operation. High velocity jets of the coolant 21 issue from the tips 52 of the nozzle tubes 44 and impinge against the concave rear surface R to produce a film of the coolant travelling longitudinally along the belt 16. This coolant 21 travels at high speed through the grooves 40 until the line of inflection 38. As the coolant rushes along the concave surface R centrifugal force produces an intimate contact between coolant and belt to provide a highly effective heat transfer so that the belt is intensely cooled.
In order to cool the belt as it runs around the drum, the coolant 21 is impinged against the rear face R near one edge, as shown in FIGURES 4 and 5 so that the coolant travels at high speed across the convex belt surface and flys off from the opposite edge to be caught in a shield 54.
A large number of nozzles 56 are connected to a header pipe 58 extending in an arc concentric with the axis of the drum 14 and located near one edge of the belt '16. In this machine there are approximately sixty of the nozzles 56 and they are uniformly spaced along the length of the header 58. Each nozzle is directed toward the face R to impinge near the edge of the belt. The axis of each nozzle 56 is aimed at a small angle to the surface R, for example this angle is in the range from 6 to 20, so that the coolant impinges to spread out and form a fast travelling film 60 (FIG. 5) moving transversely across the face R.
In order to remove the longitudinally travelling coolant beyond the line 38 of the reverse curvature, there is an initial sequence of nozzles 61, 62 and 63 which are aimed in the direction of travel at progressive-1y decreasing angles A, B, and C. Their jets effectively drive beneath the longitudinally travelling coolant so as to raise the longitudinal coolant from the face R while deflecting it and sweeping it aside. Thus, a film of high speed coolant is maintained against the face R and a transition is made from longitudinal to transverse flow. This transition is made at the beginning of the convex curvature of the face R.
The header 58 is made in three sections joined by flanges 64, and coolant i supplied under pressure to the header 58 through a plurality of lines 66. By supplying coolant at a plurality of connections 66 a substantially uni-form high pressure is provided throughout the length of the header 58, that is, internal pressure drop is minimized. Thus, the transversely flowing coolant layer 60 has substantially uniform velocity at all points along the belt. This provides a high rate of heat transfer and uniformity in cooling the solidifying metal being cast. The arcuate header 58 is mounted on the frame 12 by a plurality of supports 68.
In order to obtain the most effective cooling action the flexible metal casting belt 16 is made of metal of high tensile strength relatively thin and having good heat conductivity. For example, in the machine as shown this belt 16 is made of mild steel and is less than .060 of an inch thick. Thus, the intense cooling action along the rear face R produces a substantially uniform temperature at all points of the front face F adjacent to the molten metal 25.
The terms and expressions which we have employed are used in a descriptive and not in a limiting sense, and we have no intention of excluding such equivalents of the invention described as fall within the scope of the claims.
What is claimed is:
1. In the art of continuous casting of molten material in which the molten material is confined in a continuously moving mold provided by the periphery of a revolving drum and the front face of an endless flexible belt which curves partially around the revolving drum, and in which the belt curves in the opposite direction as it approaches the drum, causing the rear face of the belt first to assume a concave curve as it approaches toward the drum and then to assume a convex curve as it curves around the drum, the method of cooling the casting belt comprising the steps of flowing the coolant at high speed longitudinally along the concave portion of the rear face as it approaches toward the drum, and flowing the coolant at high speed transversely of the rear face along the convex portion of the rear face.
2. In the art of continuous casting of molten material as claimed in claim 1, the method of cooling the casting belt including the step of flowing the coolant diagonally across the rear face of the casting belt to provide a transition between the longitudinally flowing and transverse flowing coolant.
3. In the art of continuous casting of molten material as claimed in claim 2, the method of cooling the casting belt in which the diagonally directed coolant is impinged against the rear face of the casting belt so as to drive beneath the longitudinally flowing coolant while deflecting the longitudinally flowing coolant laterally.
4. In the art of continuous casting of molten material as claimed in claim 3, the method of cooling the casting belt in which the diagonally directed coolant drives beneath the longitudinally flowing coolant near the beginning of the convex curve after the longitudinally flowing coolant has passed the termination of the concave curve.
References Cited UNITED STATES PATENTS 3,279,000 10/1966 Cofe-r et al. 164-87 XR FOREIGN PATENTS 536,316 1/1957 Canada. 1,218,995 12/1959 France.
801,547 9/1958 Great Britain.
WILLIAM J. STEPHENSON, Primary Examiner.
R. S. ANNEAR, Assistant Examiner.
US. Cl. X.R. l64283
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