Description

Cluster Casting Machine and Method

Technical Field:

This invention relates to high temperature metal continuous casting machines in which the mold tubes are cooled with sprayed water or other coolant and are oscill¬ ated during a casting operation. More particularly, in accordance with the present invention the molds are grouped together in clusters so that a plurality of strands can be simultaneously cast in an area required for the casting of a single strand in a conventional machine.

Background Art:

In the conventional continuous ^' steel casting method, molten steel is passed through a vertically oriented, ^• usually curved, copper mold. The mold is typically square shaped, although it may be rectangular in the event steel slabs are to be made. As the molten steel passes through the mold its outer shell hardens. As the steel strand continues to harden, it is bent through an angle of 90° so that it moves horizontally, and it is subsequently cut into individual billets.

The temperature of molten steel is typically 2950° F, although with certain grades the temperature may be as low as 2600 °F. In general, although most of the references herein are to steel casting, the invention contemplates the casting of any metal or metal alloy whose liquid temp¬ erature exceeds 2600 °F.

The mold which forms the steel strand contains the liquid steel and provides for its initial solidification, that is, hardening of the outer shell. The solidifying strand is extracted continuously from the bottom of the mold at a rate equal to that of the incoming liquid steel

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at the top, the production rate being determined by the time required for the outer shell to harden sufficiently so as to contain the inner core of liquid, solidifying steel. In conventionally designed casting machines the strand is also oscillated while casting proceeds in order to keep the solidifying strand from sticking to the cooled copper wall and thus ruining the cast product. A conven¬ tionally designed casting mold requires a baffle tube arrangement with a water-tight and pressure-tight housing in order to maintain proper heat extraction. This results in a significantly larger sized mold housing and increased weight. The larger and heavier molds thus required neces¬ sitate several additional design features in the casting machine. The large housings and oscillation frames in conven¬ tional systems are necessary due to the conventionally designed cooling oscillation systems employed on all present day designs of continuous casting machines even ; though it would be more desirable from a design standpoint to reduce the size and hence spacing of individual molds. In conventionally designed casting machines, strand centerlines must be about 24 to 40 inches apart in the case of small billet (3 to 6 inch cross-section) casting and as much as 60 to 100 inches in the case of large slab casting because of the physical size constraints related to machine oscillation lever arms and oscillation frames necessary to effect the desired oscillating motion of the heavy mold housings during casting. Since the cooling system is also integral to the operation of the strand and is incorporated into the mold housing, all convention¬ ally designed casting machines feature single strand mold housings at the centerline spacing noted above.

Disclosure of the Invention:

Many operating and metallurgical advantages can be r'ealized by grouping or clustering the strands together

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and casting several strands at once. From a production standpoint, it is more desirable since more steel per unit time can be cast through a given caster. From a metallurgical consideration, it is more desirable since total casting time can be reduced and hence less reoxi- dation of the steel and lower strand casting temperatures can be employed.

The advantages of cluster casting are readily appar¬ ent to those skilled in the art. A conventional casting machine can be reconfigured to the invention, immediately resulting in a doubling or tripling of the production capacity of the machine. This is not possible when utilizing a conventional continuous casting mold cooling and oscillating system. The present invention is made possible by utilizing the technology disclosed in United States patents 4,494,594 and 4,483,385, without which desiqn engineers could not reduce the distance betwe ^' en strand. centerlines, nor cOuld. they group individual strands together into a single housing to form a casting cluster.

By utilizing the advantages of the spray cooled mold technology as described in patent 4,494,594 and the oscillation system as described in patent 4,483,385 and by grouping the strands and cooling systems into a cluster arrangement, it is possible to design a continuous castint machine for simultaneously casting a plurality of strands in an area in which only single strands can be cast using conventional techniques and designs.

A continuous casting machine in accordance with the invention enables the size of the machine to be reduced relative to conventional machines by clustering the strands and also enables the machine around the mold system to be designed so that additional economies of size and equipment can be realized. Accordingly, it is an object of this invention to provide a continuous casting machine in which clusters of

SUBSTITUTESHEET

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strands of metal are simultaneously cast.

Another object of the invention is to provide a continuous casting machine which enables a plurality of strands of metal to be simultaneously cast in an area presently required by conventional technology to cast a single strand.

A further object is to provide a continuous casting machine in which a cluster of molds is provided in the machine for simultaneously casting a plurality;- φf strands ^"

10 in the machine, and in which a common spray cnαrlirxg- system is used to cool the molds in the- duster.

Yet another object is to provide a continuous casting machine inwhich a cluster, of molds is provided in the machine for simultaneously casting- a. plurality of

15 strands in the machine, and in which a common oscillating means is connected with the molds ^' in the cluster for oscillating them during a- casting operation.

A still further object of the invention is to provide a continuous casting machine in which a cluster of molds

20 is provided in the machine for simultaneously casting a plurality of strands in the machine, and in which individ¬ ual spray cooling systems are associated with the individual molds in the cluster for cooling the molds independently of one another.

25 An even further object of the invention is to provide a continuous castinq machine in which a cluster of molds is provided in the machine for simultaneously casting a plurality of strands in the machine, and in which individual oscillating means are connected with individual

3. molds in the cluster for oscillating the -molds independently of one another .

Another object of the invention is to provide a method of casting strands of metal wherein a plurality of strands are simultaneously cast in a cluster of such strands.

35 These and other objects and advantages of the inventio

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are accomplished by the improved structure and method discovered by applicant for the cluster casting of strands of metal in a continuous casting machine. In the invention, a plurality of mold tubes are assembled in a cluster and are mounted in a housing. The mold tubes are spaced from one another and spray means are disposed to direct sprays of a coolant, such as water, against the tubes to cool them and the metal flowing therethrough. The spray means may comprise either a common spray system for cooling all of the mold tubes or a plurality of individual systems for cooling individual tubes. Similarly, a mold tube oscillating structure is connected with the tubes to oscillate them during a casting operation, and may comprise either a common oscillating structure which is connected with all of the tubes for oscillating them together, or a plurality.of separate oscillating structures connected with individual tubes for oscillating them separately.

In one form of the invention a cluster of mold tubes are mounted near or at their upper ends in a support plate and extend downwardly therefrom into a housing. The housing is fixed to a stationary support and the support plate on- which the mold tubes are carried is connected to an oscillating means for oscillating the support plate and mold tubes carried thereby. A water supply extends into the housing for supplying coolant to a plurality of spray nozzles spaced around the mold tubes. The spray nozzles may be mounted on spray header pipes supported in the housing, or the housing itself may be formed with passages supplying coolant to the nozzles.

In another form of the invention individual mold tubes are mounted on separate support plates for oscillation independently of each other, and individual sets of spray nozzles are arranged in association with each mold tube for individual cooling of the tubes.

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A continuous casting machine constructed in accordance with the invention results in an increased production capacity over conventional machines of from about 25% to about 200% and at the same time yields an improved metallurgical -quality of the steel produced because of the reduced casting temperature permitted by the incorporation of the invention. Other advantages, such as reduced weight and space requirements, reduction in energy requirements for operation of the plant, and increased speed of production - including decreased casting time and hence less reoxidation of the steel- clearly demonstrate the significant advance of the invention over the prior art.

Brief Description of the Drawings: The foregoing objects and advantages of the inven¬ tion -will become apparent from the following detailed description and accompanying drawings, in which like reference characters designate like parts throughout the several views, and wherein: Figure 1 is a somewhat schematic top plan view of a plurality of continuous casting machines arranged side- by-side in accordance with the prior art;

Figure 2 is a somewhat schematic side view in elevation of one of the prior art machines of figure 1; Figure 3 is a somewhat schematic top plan view of a plurality of continuous casting machines arranged side- by-side and incorporating clusters of mold tubes in accordance with the invention;

Figure 4 is a perspective view of one of the machines of figure 3;

Figure 5 is a top plan view similar to figure 3 , showing a large number of mold tubes clustered together;

Figure 6 is a fragmentary perspective view of a portion of the machine of figure 3, showing a common mold

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tube oscillating structure connected with all of the mold tubes for oscillation of them as a unitary structure;

Figure 7 is a fragmentary perspective view similar to figure 6, showing a plurality of independent mold tube oscillation structures connected with the individual mold tubes for oscillation of them independently of one another; and

Figure 8 is a somewhat schematic top plan view of a portion of a continuous casting machine for casting slabs of steel, and in which the water supply for the spray nozzles comprises passages built into the housing itself.

Best Mode for Carrying Out the Invention:

Referring more specifically to the drawings, an _^ apparatus in accordance with a first form of the invention is indicated generally at 10 in figure 3 and comprises a '' plurality of mold housings -11, 12 and 13 arranged in side-, by-side relationship and each supporting a plurality of spaced apart mold tubes 14 and 15 therein. A coolant inlet 16 is connected with a spray header system 17 inside each mold housing and spray nozzles 18 are spaced along the headers for spraying a coolant fluid such as water against the outside surfaces of each mold tube.

The spray cooling system may include valves 19 and 20 for operating the spray header system 17a for one of the mold tubes 14 independently of the spray header syste 17b- for the other mold tube 15, and an oscillation table 21, as shown in dot-and-dash lines, may be connected with the mold tubes for oscillating them during a casting oper- ation.

A system constructed in accordance with the invention can provide a pair of mold tubes 14 and 15 in a mold housing 11, with the mold tubes being spaced apart only 8 to 12 inches, center-to-center, as compared with

a center-to-center spacing of 24 to 40 inches in a prior art arrangement as shown in figure 1.

A first variation of the invention is shown in figure 4, wherein three mold tubes 22, 23 and 24 are arranged in a mold housing 25 supported on a fixed mounting plate 26. Although not shown in this figure, a plurality of spray header pipes and spray nozzles are arranged around the mold tubes for spraying a coolant fluid against the mold tubes in accordance with the teaching in US patent 4,494,594. Similarly, the mold tubes may be oscillated with a structure like that shown in US patent 4,483,385. Coolant, such as water or the like, is introduced to the spray header system via inlet 27. The three strands of metal cast simultaneously with this structure are shown exiting the apparatus at 28, 29 and 30.

A -second variation of the invention is shown at 31 in figure 5, wherein a pair of mold housings 3,2 and 33 are disposed side-by-side and six mold tubes 34, 35, 36, 37, 38 and 39 are supported in spaced apart relationship in each housing. A spray header system 40 is arranged in the housing toconduct a coolant fluid to spray nozzles

41 spaced around the tubes to cool them. With this arrangement, six strands of metal can be simultaneously cast in an area 30 inches by 30 inches square (the strands having cross-sectional dimensions of 4x4 inches) .

In figure 6 a common mold tube oscillation structure

42 is connected with all three mold tubes 22, 23 and 24 for oscillating them together. The oscillation structure compris a mold tube support plate 43 fixed at or near the upper end of the mold tubes for supporting themold tubes inside the mold housing 25' , with the lower ends of the mold tubes being suspended freely inside the mold housing in alignment with openings 44, 45 and 46 in the bottom wall 47 of the housing. As shown, the mold tube support plate 43 is guided on pins 48 at the corners, and is oscillated by means of one or more pneumatic, hydraulic or electric motors 49, 50, etc. connected with the support plate 43.

A plurality of spray header pipes 51, 52, etc. extend in the housing in spaced relation to the mold tubes to spray a coolant fluid against the mold tubes to cool the metal therein as taught in US patent 4,494,594. A modification of the mold tube oscillation system is shown at 53 in figure 7, wherein a plurality of individual oscillation structures 53a, 53b, 53c are connected with the individual mold tubes to oscillate them independently of one another. In all other respects, this form of the invention is identical to that shown and described in relation to figure 6.

A variation of the invention shown in figure 4 is illustrated in figure 8 at 54. In this form of the inventio the cluster arrangement of mold tubes is used to cast slabs of metal. In other words, large flat rectangularly shaped strands of metal are cast in mold tubes 55, 56 and 57 rangin from about 2 inches by 30 inches up to about 12 inches by 100 inches in cross-sectional dimensions. The slab mold tubes are arranged with their widest faces parallel to one another and spray nozzles 58 are disposed to spray coolant fluid against the faces of the slab molds to cool metal there in.

The unique cluster mold of the invention enables a significantly increased production of cast metal in a given amount of space and time, and eliminates the use of baffle tubes and oscillation tables connected with the mold housings as shown at 59 and 60 in figures 1 and 2, depicting prior art arrangements. In these prior art structures, cooling water inlets 61 and outlets 62 are connected with the baffle tube 59 to circulate coolant around the mold tube 63. A motor 64 is connected through an oscillation arm 65 with the oscillation table 60, to which the mold housing is fixed by hold down bolts 66.

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While the invention has been illustrated and described in detail herein, it is to be understood that various changes in construction and operation can be made without departing from the spirit thereof as defined by the scope of the claims appended hereto.