US3537507A

US3537507A - Continuous casting mold with perforated coolant distributor

Info

Publication number: US3537507A
Application number: US689968A
Authority: US
Inventors: Gunther De Rossi; Siegfried Gimmi
Original assignee: Alusuisse Holdings AG
Current assignee: Alcan Holdings Switzerland AG
Priority date: 1966-12-16
Filing date: 1967-12-12
Publication date: 1970-11-03
Anticipated expiration: 1987-11-03
Also published as: CH452121A; FR1548834A; NO118620B; NL159306B; NL6715854A; IS1702A7; SE327510B; DE1583699C3; AT278267B; BE707641A; GB1150109A; DE1583699A1; DE1583699B2; IS738B6; DK113029B

Description

atent Gunther De Rossi Singen/Hohentwiel, Germany; Siegfried Gimmi, Sierre/VS, Switzerland Inventors Appl. No. 689,968 Filed Dec. 12, 1967 Patented Nov. 3, 1970 Assignee Swiss Aluminum Ltd.

Chippis, Switzerland a corporation of Switzerland Priority Dec. 16, 1966 Switzerland 18,112/66 CONTINUOUS CASTING MOLD WITH PERFORATED COOLANT DISTRIBUTOR [56] References Cited UNITED STATES PATENTS 2,304,258 12/1942 Junghans 164/89 3,206,809 9/1965 Herrmann... 164/89 3,412,784 11/1968 Wieland 164/273X Primary Examiner-J. Spencer Overholser Assistant Examiner-R. Spencer Annear Attorney-Ernest F. Marmorek ABSTRACT: A mold for the continuous or semicontinuous casting of slabs has intercommunicating two hollow long side 10 cla'ms4nrawmg Flgs' beams and two shorter hollow end beams, and a distributor US. Cl 164/283, pipe in one or more of the beams with outlet holes that are 164/89 grouped nearer to the center than to the ends of the beam or Int. Cl 822d 11/00 beams, so that coolant in greater volume will flow from the Field ofSearch 164/82, 89, center portion of the beam out of the beam interior onto the 273, 283, slab than from the end portions ofthe beam.

Patented Nov. 3, 1970 INVENTQRS! (pad THE"? ATTORNEY.

Gunther dc P Seg/rifii Gc'mrm, BY ,M mum/ Fig.1

Fig. 4

CONTINUOUS CASTING MOLD WITH PERFORATED COOLANT DISTRIBUTOR The present invention relates to continuous or semicontinuous casting, and more particularly relates to molds of the kind used for the casting of ingot'slabs of rectangular cross section, particularly rolling mill slabs.

The instant invention is described in connection with molds that have been characterized as being for continuous or semicontinuous casting; it will be understood that wherever the term "continuous" is used it includes the term semicontinuous, and vice versa.

Molds of this kind need to be cooled. Some molds have walls formed with passages through which a coolant flows, entering through inlet pipe'connections and issuing through outlets which may be spray nozzles or slots through which the coolant is sprayed against the surface of the emerging cast slab. Other molds again have solid walls which are comparatively thin and are cooled by a spray of coolant which imp inges on the outer surface of the wall from spray nozzles arranged in a surrounding system of tubes.

in the continuous or semicontinuous casting of slabs of elongated cross section, for example rolling mill slabs, it is often an advantage to cool the wider sides of the slabs in certain regions more than in others. Usually it is desired to cool the middle part ofthe wider sides more intensively than the regions near the edges. This is particularly desirable in the casting of rolling mill slabs of which the surface is to be milled away only a little or not at all before rolling.

This desired uneven cooling has been obtained in the past by using either hollow-walled or solid-walled molds. in either it is another object ofthe invention to provide a mold of this type that is simple to manufacture, easy to assemble. and economical and reliable in use.

Further objects and advantages of the invention will be set forth in part in the following specification and in part will be obvious therefrom without being specifically referred to, the same being realized and attained as pointed out in the claims hereof.

The above mentioned disadvantages are avoided in accordance with this invention by having a mold for the continuous or semicontinuous casting of ingot slabs of substantially rectangular cross section, the mold having a side formed by a case the spray nozzles are distributed unevenly, that is to say,

where a more intensive cooling is desired, they are more closely spaced or they have larger diameters, or both. For example the spray nozzles can be grouped more closely together near the middle of the wider side of the emerging slab and/or they can have larger diameters. This solution, however, has various disadvantages and encounters certain difficulties in practice.

When a jet of water impinges on the surface of the hot slab the following effect is produced: A film of water is formed on the surface of the slab, the upper edge of the film forming a curve which is parabolic or hyperbolic, depending on the angle of the jet relative to the slab surface. When two adjacent jets impinge on the surface of the slab, the curved upper edges of the water films intersect and in order to obtain even cooling over the whole width of the slab the points of intersections of the said curves should all be substantially at the same level on the slab surface. If an intersection between the curves of the films formed by two adjacent jets is lower on the slab surface than the other intersections, the emerging slab will receive less intensive cooling at this point.

This adverse effect occurs in particular when the two adjoining jets are spaced further apart than the other jets of the row. The resultant effect produced is that the surface crystals formed in the metal will extend deeper into the skin of the slab at this point, and when the surface of the slab is subsequently milled away a line of crystals remains at this location. The line of crystals is concealed by the lines produced by the milling tool, but reappears when the slab is rolled.

in order to reduce this effect to a minimum, the spray nozzles needed to be made very accurately, both in regard to the distance for which they are spaced apart, and in regard to direction. in those cases where it is desired to produce a differential cooling of the slab surface, the necessary changes in nozzle spacing or diameter makes it difficult to obtain this accuracy, if only because it is necessary to change drills, unless comparatively expensive machine tools are used. Moreover,

the necessarily precise machining operations must be repeatedfor each length of mold.

in the case ofa mold with a continuous spray slot instead of a row of nozzles, differential cooling is difficult if not impossible, due to the troubles of cutting a slot of varying width.

It is accordingly among the principal objects of the invention to provide a mold of this type that avoids the drawbacks of the prior art.

hollow side beam or side member which encloses a distributor pipe that extends along the interior of the side beam with a number of outlet holes grouped nearer to the center than to the ends of the side beam. A coolant is supplied to the distributor pipe and by this pipe is led into the interior of the side beam; and the side beam is provided uniformly along its length with at least one opening through which in use coolant can pass from the interior of the beam emerging from the mold in use on to a side of the slab, so that a greater volume flow of coolant is directed on to a center portion of the side of the slab than to portions ofthe side of the slab near its edges.

The side beam can be provided with either a continuous slot or a row of nozzles for directing the coolant from its hollow center onto the slab.

The distributor pipe can if desired extend over only a part of the length of the mold, in which case it is fed with coolant through pipe connections which penetrate through a wall of the hollow side beam. The distributor pipe together with the pipe connections then forms a T-shaped or L-shaped structure. After this structure has been inserted into the side beam, the openings in the side beam will be sealed, for example by covers secured to the pipe connections.

in accordance with a preferred embodiment, however, the distributor pipe projects through at least one oftwo end beams of the mold, and the projecting end serves as the inlet connection for the feed ofthc coolant.

Due to the grouping of the outlet holes near the middle of the distributor pipe, the hydraulic pressure head driving the coolant out through the regularly spaced spray nozzles, or out thiough the slot of constant width, is greater towards the middie of the side beam, and consequently the spray of coolant issues in larger volume than near the edges of the side beam.

The distributor pipe preferably extends at both ends through the end beams of the mold. The coolant can then be fed into the distributor pipe through both ends. This arrangement gives better control of the hydraulic pressure distribution behind the spray nozzles or spray slot, particularly in the case of a long mold. in the case of a long mold, feeding the.

coolant into one end only of the distributor pipe leads to difficulties because of the pressure gradient inside the distributor pipe.

A further advantage of the arrangement in which both ends of the distributor pipe projects outwards through the end members of the mold frame is that the mold, assuming it to consist of two side beams and two end beams, can be assembled by using the two distributor pipes as tie rods, the ends of the side beams forming butt joints with surfaces provided for the purpose at the ends ofthe end beams.

in this case the side beams can be manufactured in the form of long, hollow beams and be sawn off to length as required. The evenly spaced spray nozzles, or spray slots of constant width, can be machined in the side beams with sufficient accuracy, using a special machine, either before the side beam is cut to length or afterwards. The end beam can for example be molded. In this way molds of different dimensions can easily be assembled from side and end beams of different lengths. The length of each distributor pipe must of course suit the length of the corresponding side beam.

The distributor pipes are easy to manufacture because the outlet holes need not be drilled very accurately, either in diameter or in direction; the hydraulic pressure in the interior of the side beam distributes itself in any case fairly evenly between adjoining outlet holes. These outlet holes can be drilled in the distributor pipe by using an ordinary manual drill, if necessary with the help ofa ruler.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description, taken in connection with the accompanying drawings, in which:

FIG. 1 is a fragmentary plan view, partly in section, of a mold in accordance with an embodiment of the invention;

FIG. 2 is a sectional view taken on the line A-A of FIG. 1;

FIG. 3 is a sectional view taken on the line B-B of FIG. 1; and

FIG. 4 is a fragmentary end elevational view of an end beam.

In carrying the invention into effect in the embodiments which have been selected for illustration in the accompanying drawings and for description in this specification, and referring now particularly to FIG. 1, there are provided two hollow side members or side beams l, and two end members or end beams 2 which are connected to the side beams l by means of two distributor pipes 3. The distributor pipes 3 act as tie rods, giving a positive mechanical connection between the beams.

The side beams l are of rectangular cross section as is usual. Each side beam 1 has a row of spray nozzles 4 drilled at equal spacing through the lower, inner edge of the wall, and all the nozzles 4 have the same diameter. Each spray nozzle 4 is drilled through the wall of the side beam 1 at an angle of about 30 relative to the inner surface of the beam. The bore hole diameter of each nozzle 4 is constant at 2.5mm. and the nozzles 4 are spaced apart at a constant spacing of about 5mm. between the centers of the bore holes. If the spray nozzles are drilled through the wall of a side beam 1 of which the corner has already been sawn off, however, and if it is desired to produce reduced cooling near the corners of the cast slab, then if desired the first spray nozzle 4 near the corner of the slab can be spaced for a greater distance from the corner, for example for a distance of mm.

Each end beam 2 preferably comprises a trough-shaped casting 5 which has connecting webs 6 for connecting the end beams 2 to the two side beams l of the casting .mold. Each connecting web 6 has two contact surfaces 7 which rest against the end surfaces of the side members 1 so that a butt joint is formed. Each trough-shaped end beam 2 is closed by a cover plate 9, that is held be means of screws 8, so that the interior of the end beam 2 forms an internal chamber to contain the cooling medium.

Each end beam 2 also has spray nozzles 4. These spray nozzles may have the same diameter as for the side beams l but can, if desired, have instead different diameters from those of the side beams 1.

In the hollow interior of each side beam I there is disposed a distributor pipe 3 which, as previously indicated, not only distributes the cooling medium but also acts as a tie rod. The two ends of the distributor pipe 3 are externally threaded and project through the connecting webs 6. Nuts 10 are mounted over the projecting ends of the distributor pipe 3 and hold the entire assembly together; A watertight sealant can be applied between the contact surfaces 7.

Each distributor pipe 3 has a series of holes 11 in its middle region. These holes 11 can be arranged in one row or in several rows, and they are preferably so positioned circumferentially that the jets of coolant issuing from them do not impinge at right angles against the inner wall of the side beam 1, as this would cause excessive local cooling.

Again, to prevent excessive local cooling of the wall, the holes I] in the distributor pipe 3 have relatively large diameters, for example more than 5mm. and preferably between 8 and 10mm., to prevent the production of any rapid jet of water from the hole and any attendant shower spray.

The part of the distributor pipe 3 which is drilled in this way must be shorter than the length of the side beam 1, that is to say, shorter than the length of the mold. The length of the section of the distributor pipes 3 in which the holes 11 are concentrated is preferably between 20 percent and percent of the inner length of the side beam 1, and for most applications the length of the middle portion will be between 35 percent and 60 percent of the inner length of the side beam 1. In accordance with a preferred embodiment, the distributor pipe 3 has holes 11 along about 50 percent of the inner length of the mold.

The difference in hydraulic driving pressure along the length of the side beam 1 is of course greater if the drilled section of the distributor pipe 3 is shorter. The difference between the velocities of the water jets issuing from the spray nozzles 4 can be detected quite easily by passing a hand along the inner edge of the side beam 1. The cooling medium is fed up to the distributor pipe 3 through branched connections (not shown) attached to thetwo ends ofthe pipe 3.

For feeding the coolant to the end beams 2, there can be provided special connections. In practice, however, the narrow sides of the cast slab do not need to be cooled as much as the wide sides, and it has been found that the end beams 2 of the mold receive a sufficient flow of coolant if the connecting webs 6 are formed with passages 12. The coolant flows from the hollow interior of the side beams 1 through the passages 12 into the internal chambers ofthe end beam 2.

The passages 12 can either be drilled or be formed during the casting of the end beams; in the latter case, the passage 12 can be made large enough to supply enough coolant to the end beam 2 even if there is only one passage between the side beam 1 and the end beam 2. For adjusting the supply of coolant, a screw 13 can be provided in one or in each passage 12, the end of which projects adjustably into the passage 12.

We wish it to be understood that we do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

We claim:

1. A mold for the continuous or semicontinuous casting of ingot slabs of substantially rectangular cross section, comprismg:

two hollow longer side beams and two shorter hollow end beams;

at least one distributor pipe longitudinally disposed in the interior of said side beams and having a series of outlet holes grouped nearer to the center than to the ends of said side beams for admitting coolant supplied to the distributor pipe into the interior of said side beams;

each of said side beams,defining uniformly 'along its length near the mold bottom at least one opening through which coolant can pass from the interior of the beam on to a side of the cast slab emerging from the mold, for directing a greater volume flow of coolant on to a center portion of the side of the slab than to portions of the side of the slab near its edge.

2. A mold according to claim I, in which the outlet holes in the distributor pipe are grouped in the center section forming from about 20 percent to 80 percent of the inner length of the beam.

3. A mold according to claim 2, in which the holes in the distributor pipe are grouped in the center section forming from about 35 to 60 percent of the inner length of the beam.

4. A mold according to claim I, in which the outlet holes in the distributor pipe have a diameter of at least 5mm.

5. A mold, as claimed in claim 4, said outlet holes having diameters of from about 8mm. to about 12mm.

6. A mold according to claim 1 in which the distributor pipe is disposed in a side beam and projects beyond at least one of said two end beams, the projecting end serving as a connection for supplying the coolant.

7. A mold according to claim 1, in which a distributor pipe is disposed in each side beam, the distributor pipes projecting at either end beyond both end beams and the projecting ends of the distributor pipes serving to attach the end beams to the side beams, by a butt joint, whereby the distributor pipes function as tie rods.

beams.

10. A mold according to claim 8, in which at least some of said passages between the side and end beams are equipped with an adjustment means for adjusting the flow of cooling medium therethrough.