US3651857A

US3651857A - Device for supporting and cooling continuously cast strands of metal

Info

Publication number: US3651857A
Application number: US50465A
Authority: US
Inventors: Wilhelm Koch
Original assignee: Demag AG
Current assignee: Mannesmann Demag AG
Priority date: 1969-10-18
Filing date: 1970-06-29
Publication date: 1972-03-28
Anticipated expiration: 1989-03-28
Also published as: FR2064415B3; JPS4926419B1; DE1952633A1; FR2064415A7; DE1952633B2

Abstract

A supporting device for supporting cast strands of metal as they are fed from a casting mold, comprises a supporting frame which is adapted to be positioned adjacent the casting mold and which carries a plurality of longitudinally spaced rows of transversely extending cross members. Each cross member carries a plurality of supporting members in the form a rotatable rolls which are arranged in transversely spaced orientation with the supporting members of adjacent rows being laterally offset and extending between the adjacent support members of each next adjacent row. The supporting members are dimensioned as small as possible and the cross member advantageously includes means for directing a fluid spray outwardly in a pattern to provide adequate cooling for the casting which is supported on the device.

Description

O United States Patent 1 3,651,857 Koch [4 1 Mar. 28, 1972 [54] DEVICE FOR SUPPORTING AND 3,268,956 8/1966 Lemper ...l64/282 COOLING CONTINUOUSLY CAST 3,536,127 10/1970 Tafel ..164/89 X STRANDS 0F METAL FOREIGN PATENTS OR APPLICATIONS [721 Wilhelm Duisburg Germany 1,399,695 .4/1965 Great Britain ..l64/282 [73] Assignee: Demag Aktiengesellschaft, Duisburg, G 153,721 3/1956 Sweden ..l64/82 many Primary Examiner-R. Spencer Annear Flledi J 1970 Attorney-McGlew and Toren [21] App]. No.: 50,465 ABSTRACT A supporting device for supporting cast strands of metal as [30] Foreign Apphcaflon Pnomy Dam they are fed from a casting mold, comprises a supporting Oct. 18, 1969 Germany P 19 52 633,1 frame which is adapted to be positioned adjacent the casting mold and which carries a plurality of longitudinally spaced 521 U.S.Cl ..164/283, 164/89, 134/83, rows of transversely n ing ro m mbers- Each cross 134/199 member carries a plurality of supporting members in the fonn 51 Int. Cl ..B22d 11/12 a rotatable rolls which are arranged in transversely spaced [58] Field of Search ..164/82, 89, 282, 283; 134/49, Orientation with the Supporting members of adjacent rows 134/64 82 83 122, 165, 199 being laterally offset and extending between the adjacent support members of each next adjacent row. The supporting [56] References Cited members are dimensioned as small as possible and the cross member advantageously includes means for directing a fluid UNITED STATES PATENTS spray outwardly in a pattern to provide adequate cooling for the casting which is supported on the device. 2,804,663 9/1967 Harter, Jr. et al ..164/283 X 2,895,190 7/1959 Bungeroth et a1. ..l64/282 10 Claims, 5 Drawing Figures PATENTEB M828 I972 SHEET 1 BF 2 Fig. 7'

Inventor WILHELH KOCH HITD'RVEY! DEVICE FOR SUPPORTING AND COOLING CONTINUOUSLY CAST STRANDS OF METAL SUMMARY OF THE INVENTION 1 This invention relates in general to continuous casting apparatus, and in particular, to a new and useful supporting device particularly for cast steel strands which includes a plurality of supporting elements with spray means for spraying a cooling fluid in the vicinity of a casting which is supported.

Usually the cast strand solidifies in the continuous casting mold only to the extent of having, upon leaving the mold, a relatively thin skin consisting of cast metal below the point of liquidity. In this condition the strand easily tends to bulge at the supporting elements which for example, may comprise either rollers, rolls or plates. Such bulging entails the danger of the strand breaking and the bulges increase the transport resistance, the individual resistances adding up to a total resistance which must be overcome by the strength of the strand transporting machine. Therefore the greater the friction at the bulges, the greater the drawing resistance and the greater the driving output of the transporting machine. In addition, the stress on the strand skin will be great and this skin is usually weak to start with and this could produce particularly serious consequence. In practice therefore, an increase in the casting speed and an increase in output are possible in rare cases.

The slower that the strand is cooled the more is the danger that the strand will break off provided the casting speed is increased. In order to prevent bulges or breaks, the strand is supported, after it leaves the mold, and it is cooled at the same time. The more intensive the cooling, the more the skin growth is accelerated. Therefore, the process of supporting and cooling goes hand in hand and can methodologically not be separated. This results in problems involving the known supporting devices with which the cooling devices must be associated.

It is known to dispose through rollers at the broad side of the strand at a location below the continuous casting mold for instance, where slabbing strands are involved. The greater the roller diameter selected, the greater the distance between the several rollers. It is also known to attach one or two such rollers directly to the continuous casting mold while the others are mounted in a stationary supporting device. The roller spacings must be chosen so that there is the possibility of providing a number of spray nozzles to cool the strand appropriately between each two rollers over the entire width of the strand. It is also known to provide several metal plates below the continuous casting mold, so-called cooling shoes, which support the strand at the sides of its profile. The metal plates form closed cooling boxes with a definite system of plate arrangement in order to cool the latter as well as bring coolant to the strand in addition. However, the metal plates cover the strand to such an extent that the desired cooling effect fails to materialize for reasons of the so-called Leidenfrost phenomenon. The coolant which gets between the strand surface and the metal plate through the internal holes evaporates, thereby developing an insulation effect which is a known attribute of water vapor. Fresh coolant can flow only under difficulties and the developed vapor remains too long, therefore, to cause a cooling effect to the desired degree. Consequently, unless success is achieved in rinsing away the water vapor in time and at least to replace it by vapor of lower temperature, to effect the heat dissipation by evaporating the coolant, the cooling effect is insufficient and therefore the strand skin growth is also poor. An advantage inherent in the metal plates, namely the direct contact of the strand with the plate surface is therefore overcome by the disadvantages described.

In order to eliminate the above described disadvantages, it is now known to provide alternating rows of large and small supporting rollers on a fixed shaft member and to have each of the two neighboring rollers of larger diameter of the next adjacent shaft, in the travel direction of the strand, arranged in opposition to a smaller protective part of the proceeding shah. This is done in an attempt to support the strand on its surface by bearing points in the manner of a honey-comb pattern in order to keep the bulges small. Obviously, however, only the goal of support is achieved without giving the specialist an instruction on how also to solve the problem of better cooling because a disadvantageous covering effect respecting the coolant is inherrent with such a gridlike supporting element arrangement. Therefore, cooling water can penetrate only between the remaining gaps of the various roller diameters, that is, between the small and the big rollers. A desired cooling effect is consequently lacking. However, the configuration of the big rollers provided also brings with it the disadvantage of having to dimension the mutual spacing of the stationary shafts by a correspondingly greater amount as a function of the diameter of the big rollers. Therefore, in reality, two difficulties have not been overcome by the known solution. The one relates to the transmission of large forces to the strand skin, by the larger diameter rollers as the size of the honeycomb pattern increases and the other disadvantage relates to the possibility of cooling the strand which ultimately can only be drawn readily if the strand skin growth can be improved so that the greater resistance due to bulging disappears. Accordingly, the emphasis in the known object is on the support neglecting the cooling aspect.

In accordance with the present invention, there is provided a supporting device which is capable of distributing the supporting forces even better and above all takes into a better account the possibilities for cooling. With the inventive construction, the supporting elements are arranged on transverse members or cross shafts at definite spaced relationship in longitudinal rows of shafts with the supporting members on adjacent shafts being disposed between two adjacent supporting members of the next adjacent row. The dimensions of each supporting element is selected as small as possible and partial lengths of each cross support or shaft is kept free for the inclusion of a cooling device. This provides a close checker boardlike support and small gaps remain between the supporting elements which permit the dissipation of the steam from the cooling liquid. One advantage is that the strand is better supported by unit of area due to the more densely staggered supporting elements so that strand is subjected to less bulging than heretofore. The frequency of the points of contact of the supporting elements on the surface of the strand also permits the dissipation of a greater amount of heat.

Making the network of the supporting points or tacking points of forces denser protects the strand, particularly immediately adjacent the continuous casting mold so that surface cracks are avoided. Consequently the supporting forces may be weaker, and, despite the denser network of supporting forces, the strand is cooled better and there is also cooling of the rollers and cooling of the shafts supporting the rollers from the outside. The cooling is advantageously provided by conducting a cooling liquid through the shafts and discharging it through noules arranged between the individual supporting elements. This means that no separate nozzle system with separate conduit supplies are required and such systems are usually cumbersome particularly in case the strand breaks off and they hinder the readjustment to different casting strand dimensions. In contrast thereto a cooling device disposed on the shaft elements in the gaps between the supporting members always maintains the same spacing from the strand.

The supporting elements are advantageously disk shaped supporting rollers which are arranged at spacings greater than the disk width and which extend at their outer peripheries closely to the next supporting shaft of the next row. The supporting shafts are mounted in side blocks of a machine frame and the supporting elements are thus supported almost without friction so that the drawing resistance can be kept smaller precisely at that part of the strand skin which is particularly thin. It is possible therefore according to the invention, to provide for greater casting speed.

The above implementation form operates with less friction due to the fact that the supporting elements are mounted for rolling movement. However, in certain cases in which heat dissipation should be particularly great it is especially advantageous if the supporting elements consist of plates disposed in rows, with the rows having gaps into which the plates of the adjacent support members extend. Each plate is connected to the support member by an arm. Here again, the gaps between the plates and the support members are sufficiently great so that water vapor can be dissipated readily. Consequently, a particularly advantageous motor cooling consists in providing for heat transfer to the plate solely by contact with the strand and cooling the plates externally by spraying cooling water on them. This creates similar conditions of heat dissipation as exist in the continuous casting mold except that such small plates shape supporting elements cannot be provided inside a continuous casting mold so that the specialist has so far been prevented from employing them in the lower regions of the casting mold. The multiplicity of supporting elements of plate shape therefore pennits the disposition of a relatively short frame under the continuous casting mold or of course the provision of a combination of rollers and plates. Consequently, it is desirable that the plates be arranged contiguous to the continuous casting mold and a short distance thereafter a frame with cross shafts or supports to which the disk rollers are attached.

In a further development of the invention, there are added particularly inventive measures which improve the cooling effect. The cross members of shafts are made hollow and these hollow interior shaft passages supply the coolant to nonles which are arranged thereon to discharge the coolant against the surface of the strand'and they are oriented in the gap between two supporting elements. This measure combines two advantageous measures simultaneously. The cross shafts themselves are cooled and therefore dissipate amounts of heat absorbed by heat radiation and at the same time the space still available between two supporting elements is utilized to introduce cooling water. Such a construction is superior to the state of the art because separate spray nozzle lines comprising a multiplicity of longitudinal and transverse lines are obviated, thus facilitating especially the readjustment of the supporting device to a new strand dimension. For a long time the complicated structure of the coolant supply system has been a great hinderance to the specialist in case of strand breakages which are now eliminated.

An improved cooling effect can be achieved by orienting the center line of the nozzles obliquely to the strand surface and into the space between two supporting rollers. In practice this accomplishes an adaptation of the cooling system to the checker boardlike supporting system. No longer is there a gap between the various impact areas of the jet spray nozzles. Consequently the strand is cooled more intensely than heretofore. The cooling action considered over the width of the strand is also more uniform. An area of the strand once cooled will not get into a zone which is not charged by coolant for a longer period of time.

A further improvement of the invention comprises the use of additional cooling lines between the hollow interiors of the cross shafts and an outside diameter of the supporting roller shaft which serves as a journal. These branch offs from the interior of the cross shafts serve either for the cooling of the supporting roller journal or the cooling of the bearing point itself and bring about a certain lubricating effect.

The principal of internal cooling can also be further developed by arranging a group of cross shafts with supporting elements within a frame structure with one or more frame members which themselves provide means for conducting a coolant material. Using the longitudinal means of the cross frame for the conducting of the liquid coolant also permits a connection of this cross frame member to the individual supporting shafts for conducting the coolant out to the nozzle members located along the length of the cross shafts.

In accordance with further characteristics between the upper and the lower beam parts are arranged spacers, the length of which may be varied by means of shims in accordance with different strand thicknesses. This measure serves to set up the supporting device symmetrically with the spacing, always remaining uniform and limiting the efforts and time required for changing over. The basic suggestion of the checker board-type arrangement for the supporting of the strand plus the cooling arrangement provides an improved supporting and cooling feature. The supporting elements themselves in the form of rollers supported on the cross shafts may be such that they extend at their periphery into recesses defined on the cross shafts for this purpose.

Accordingly, it is an object of the invention to provide an improved device for supporting and cooling a strand from a continuous casting machine which includes a supporting frame having a plurality of longitudinally spaced rows of transversely extending cross members supported on the frameand a plurality of supporting members on the cross members arranged in transversely spaced orientation with the supporting members of adjacent rows being laterally offset and extending between adjacent supporting members of the next adjacent row and which further advantageously includes means for supplying a coolant at selected locations along the supporting members.

A further object of the invention is to provide a supporting structure for use in association with a continuous casting mold and which advantageously includes a cross member associated with the exit of the mold having at least one supporting member extending across the width thereof and carrying a plurality of spaced supporting members thereon, said cross member including means for directing a cooling spray from the supporting member at the locations between the supporting elements.

A further object of the invention is to provide a continuous strand supporting and cooling device which is simple in design, rugged in construction and economical to manufacture.

The various features of novelty which characterize the invention, are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described apreferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a top plan view of a supporting device for supporting cast strands of metal constructed in accordance with the invention;

FIG. 2 is a section taken along the line lI-Il of FIG. 1;

FIG. 3 is a section taken along the line IIII II of FIG. 1;

FIG. 4 is an enlarged partial sectional view of a portion of FIG. 2; and

FIG. 5 is a view of a portion of the device indicated in FIG. 1 showing the arrangement of the spray means for cooling.

GENERAL DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings in particular, the invention embodied therein comprises a supporting device generally designated 2 which is arranged adjacent the discharge of a continuous casting mold l which is filled continuously with a liquid metal. In the embodiment shown, the continuous casting mold carries projecting portions or

brackets

3 and 4 at its underside 5 which together with

intennediate projecting brackets

7 and 8 support a cross member or shaft 6. In accordance with a feature of the invention, the plurality of supporting elements in the form of plates or rollers 9 are rotatably mounted on the shaft 6 and they are arranged to engage and run with the movement of the continuous casting strand 28 which is delivered from the mold 1.

In accordance with a further feature of the invention, the supporting frame 2 is mounted at a spacing 11 away from the supporting elements 9 which are directly adjacent the discharge of the continuous mold 1. The supporting device 2 is made up as a partial section 12 which may extend for example in a slabbing machine for one or two meters below the casting mold 1 after which may be arranged the known type of supporting devices because controlled cooling is no longer required.

Each partial section 12 includes right and left longitudinal beams 13 and 13' which are interconnected by upper and lower cross beams 15 and 14, respectively. Spacer beams 16 and 17 are arranged between the cross beams 14 and 15 to form the entire frame of the partial section 12. The partial section 12 may of course be repeated several times in the travel direction of the strand 28.

In accordance with a further feature of the invention, the frames include side support blocks 22 and 23 which support cross support members generally designated 20 in the form of shafts 21 which are mounted in the

blocks

22 and 23. The shafts 21 are arranged in longitudinally spaced transverse rows and each shaft carries a plurality of supporting members 18 in the form of rotatable rollers 19 which are arranged in spaced transverse relationship. The rollers 19 are mutually spaced by a distance 24 in such a manner that a roller of each row is arranged between two adjacent rollers of the next adjacent row in the space 24 and without its circumference 25 touching the surface 26 of the shaft 21. Gaps 27 are thus created through which steam can be continuously dissipated without trouble.

In FIG. 2, it is seen that the rollers 19 are arranged as close to each other as possible and their peripheries 25 intersect. The strand 28 involves a slab profile as indicated in FIG. 3 and therefore the dimensioning factors governing the supporting device are based on a steel slab strand. The longitudinal beams 13 are hollow so that cooling water may flow through them in case no separate lines are provided for this purpose. The shafts 21 are also made hollow and are advantageously provided with a center cavity or passage 29 for a coolant such as water. Coolant nozzles 30 are arranged along the length of the shafts and they connect to the passages 29. They are oriented so that the discharge 31 extends obliquely to the surface 32 of the strand as shown in FIG. 4. In the arrangement shown in FIG. 5, however, the shape of the spray jet 33 may result in an uninterrupted spray surface over the width of the cast strand 28. Accordingly with the inventive arrangement the cooling of the strand is more uniform and it has the particular advantage that no interruptions of spray areas will occur when other strand dimensions are involved. When modifying this spacing to accommodate a new strand dimension the spacing of the nozzles from the strand will remain the same because the diameter 25 of the rollers 19 will be the same and therefore the shafts 21 will also be the same, thus preserving the spacing of the spray orifices 33.

In the arrangement shown in FIG. 4, the nozzles are oriented at an angle to each other but of course a single nozzle having a center line oriented perpendicular to the strand may also be provided or be provided alternatively if desired. A particularly intensive cooling action is obtained when perpendicular nozzles as well as oblique ones are provided and neither of these kind need necessarily be oriented in the plane of FIG. 4. In the arrangement shown in FIG. 5, such nozzles oriented obliquely against the surface of the strand form an uninterrupted spray area over the width of the strand. These nozzles are expediently designed in the form of flat jet nozzles but solid or hollow cone nozzles may also be employed.

According to FIG. 4, the coolant nozzles 30 are advantageously mounted so that their sprays will meet at the location T/2 on the strand surface. T signifies the spacing of the rollers 19 running one behind the other in one strand width sector. There are further coolant lines 33 extending from the central passage 29 and the outside of the profile 34 of the shaft 21. It is through these lines that the coolant reaches, as a lubricant, the race between the roller 19 and the shaft 21 which is not shown.

The invention is applicable quite generally to all strand thicknesses and is particularly advantageous for slab strands. Adjustment to various strand dimensions can be made due to the

spacers

16 and 17 and the shims 35 of various thickness.

It is possible to spray with traditional spray nozzles into the still remaining gaps of the checker boardlike arrangement of the rollers 19 which, however, means the application of the invention in a most simple form. Optimum cooling action is attained in that the coolant nozzles 30 and the central passage 29 are employed to distribute the coolant. This also increases the efficiency of the cooled rollers. An even closer configuration of the supporting rollers 19 can be achieved by making the outside diameter 34 of the shafts 21 with a flat 36 so that the periphery 25 of a roller 19 can be brought even closer to the shaft 21. The flat 36 need not necessarily be designed as drawn but may comprise a recess 37 produced by a tool having a slightly larger diameter than the diameter 25 of the supporting roller 19.

I claim:

1. A supporting device for supporting casting strands of metal as they are fed from a casting mold, comprising a supporting frame adapted to be positioned adjacent the casting mold, a plurality of longitudinally spaced rows of transversely extending cross members supported on said frame, a plurality of supporting members on said cross members arranged in transversely spaced orientation with the supporting members of adjacent rows being laterally offset and extending between the adjacent support members of each next adjacent row, said supporting elements being dimensioned as small as possible, and including cooling means for supplying a coolant through said cross members directly to the casting strand and for discharging the coolant between said supporting members along the length of said cross members.

2. A supporting device, according to claim 1, wherein said support members comprise disk shaped supporting rollers.

3. A supporting device, according to claim 1, wherein said supporting frame includes a bearing block at each side, said cross members being supported at each end in respective bearing blocks, said supporting members being rotatably supported on said cross members.

4. A supporting device, according to claim 1, wherein said supporting elements comprise supporting plates disposed in rows, said plates being spaced apart to define gaps into which the plates of the next adjacent rows extend with clearance.

5. A supporting device for supporting casting strands of metal as they are fed from a casting mold, comprising a supporting frame adapted to be positioned adjacent the casting mold, a plurality of longitudinally spaced rows of transversely extending cross members supported on said frame, a plurality of supporting members on said cross members arranged in transversely spaced orientation with the supporting members of adjacent rows being laterally offset and extending between the adjacent support members of each next adjacent row, said cross members comprising hollow shafts defining a passage for a coolant liquid, a plurality of cooling nozzles on said shaft communicating with said passage and arranged to discharge the liquid in a direction toward said strand and being located between said supporting members.

6. A supporting device, according to claim 5, wherein said nozzles are oriented oblique to the strand surface and directed into the space between the two adjacent supporting members of the next adjacent rows.

7. A supporting device, according to claim 1, including two supporting frames comprising an upper supporting frame and a lower supporting frame each carrying said cross members and said supporting members, and spacer means between said frames for holding said frames at a width comparable to the width of the strand to be moved between said frames.

8. A supporting device, according to claim 7, wherein said spacer means includes shims for varying the spacing between said frames to accommodate variations of strand thickness.

9. A supporting device, according to claim 1, wherein said cross members include recess portions between adjacent supporting members defining a space for receiving the supporting member of the next adjacent row.

10. A device, according to claim 9, wherein said supporting members are of circular cross section, the recess being formed by a flat portion of said cross section.

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