US2850776A

US2850776A - Roll constructions for continuous casting machines

Info

Publication number: US2850776A
Application number: US625971A
Authority: US
Inventors: Joseph L Hunter
Original assignee: Hunter Engineering Co
Current assignee: Hunter Engineering Co
Priority date: 1956-12-03
Filing date: 1956-12-03
Publication date: 1958-09-09
Anticipated expiration: 1975-09-09

Description

Sept. 9, I958- a. L. HUNTER 2,850,776

ROLL consmucnon's FbR CONTINUOUS czsmu: MACHINES 'FiledTDep. s, 1956 2 Sheets-Sheet 1 INVENTOR. 4 .g/bas w L11? 00 72? J. L. HUNTER Sept. 9, 1958 aozpcousmucwxous FOR courmuous CASTING mxcnmzs Filed Dec. s, 1956 2 Sheets-Sheet 2 INVENTOR. I n/OSEML/fib/YEQ- Unite States Patent ROLL CONSTRUCTIONS FOR CONTINUOUS CASTING MACHINES Joseph L. Hunter, Riverside, Califl, assignor to Hunter Engineering Co., Riverside, Calif., a corporation of California Application December 3, 1956, Serial No. 625,971

Claims. (Cl. 22-575) This invention relates to roll constructions for continuous casting machines, more particularly to roll constructions wherein a pair of rolls are disposed in parallel relation and form with a molten metal supply nozzle a casting chamber, occupying a limited segment of the rolls, the solidified metal being discharged from between the rolls at the upper extremity of the casting chamber.

This invention is a continuation-in-part of the machine disclosed in the copending application Serial No. 516,621, filed June 20, 1955, now Patent No. 2,790,216, for Method and Apparatus for the Continuous Casting of Metal by Joseph L. Hunter.

Included in the objects of this invention are:

First, to provide a roll construction wherein the walls of the roll overlying the coolant passages are relatively thick, and are predesigned to have a. heat-absorbing capacity sufiicient to extract the desired heat from the metal as the roll walls progress past the casting chamber and thereafter transfer the heat to the coolant until, at the entrance region of the casting chamber, all of the previously absorbed heat has been removed by the coolant.

Second, to provide a roll construction with a multiplicity of helical coolant passages, each having one convolution from one end to the other of the roll, so that the coolant flowing in each passage crosses the hot casting chamber zone only once and continues to extract heat throughout its helical, single convolution travel, thereby providing particularly eflicient cooling means.

With the above and other objects in view, as may appear hereinafter, reference is directed to the accompanying drawings in which:

Figure l is a side view of a roll embodying the invention, with the bearing ends shown fragmentarily and with portions of the roll in section. to illustrate its internal construction;

Fig. 2 is a transverse sectional view through 22 of Fig. l, and showing a pair of rolls in their operative position in a continuous casting machine, the casting nozzle and the cast metal formed between the rolls being shown fragmentarily;

Fig. 3 is a transverse sectional view through 33 of Fig. l. v

The roll includes a cylindrical core 1 having coaxial journals 2, extending from opposite ends, which are mounted in appropriate bearings, not shown. Formed in the periphery of the core 1 is a plurality of helical channels 3 which form therebetween helical lands 4. Each helical channel 3 extends from the axial end of the core to the other and makes approximately one convolution. The axial ends of the channels 3 intersect annular channels 5 adjacent the ends of the roll.

The annular channels 5 communicate with radiating passages 6 extending to the center of the roll. Each set of radiating passages may communicate with corresponding axial passages extending through the journals 2. However, it is preferred to utilize only one of the journals so that coolant may be brought into and discharged from one end only of the core 1; therefore, the core is provided with a bore 7 extending axially therethrough from one of the journals and communicating with the remote set of radiating passages 6.

The outer end of the bore 7 is counterbored, as indicated at 8, the counterbore intersecting the second set of radiating passages 6. A tube 9 is screw-threaded into the bore 7 and extends outwardly through the counterbore 8 so that the tube and bore may form an inlet and the counterbore an outlet, or conversely.

The core 1 receives a sleeve 10 which is preferably shrunk-fitted thereon and is supported by the helical lands 4. The ends of the sleeve 10 overlie the annular channels 5. End rings 11 overlie the ends of the core 1 and close the ends of the sleeve 10. Formed between the end rings 11, core 1, and sleeve 10, at each end of the core, is an annular O-ring groove 12 which receives an O-ring 13 for the purpose of sealing the axially outer sides of the annular channels 5.

As shown in Fig. 2, a pair of rolls are mounted for rotation about parallel axes with their surfaces spaced slightly to define the thickness of the material to be cast. Mounted under the rolls is a nozzle structure 14 formed of refractory material capable of containing, in a molten state, the metal to be cast.

The nozzle structure is essentially wedge-shaped and forms, with the rolls between its upper end and the plane common to the axes of the rolls, a substantially wedgeshaped casting chamber 15. Molten metal 16 upwells through the casting chamber and is solidified by the surfaces of the rolls so as to emerge therebetween as a solidified ribbon of metal 17. The nozzle structure and the means and method of continuously casting metal The mass of metal comprising theshell or sleeve 10 Q in the region or zone confronting or forming the casting chamber 15 is predesigned to have sufficient heat-asborbing capacity as to extract the amount of heat required to solidify the metal being cast. It will be noted that this zone occupies a very small percentage of the total circumference of the roll.

The heat absorbed by each portion of the sleeve or shell 10 as it passes the casting chamber 15 is redistributed to coolant flowing in the channels 3, during the progress of each portion of the roll from the exit region to the entrance region of the casting chamber. The particular helical, single convolution construction of each coolant channel causes the coolant flowing in each of the channels to make only one revolution, so that the bodies of coolant in all of the channels are equally exposed to the sleeve or shell and extract equal amounts of heat therefrom. As a result, the heat is etficiently extracted, as Well as uniformly extracted, from all portions of the roll. This is evidenced by the fact that the coolant may flow in either direction through the passages with equal efiiciency. While there is, of course, a slight tempera: ture gradient from one end to the other of the roll, this has no noticeable effect on the operation of the roll.

It should be observed that although the core 1 is shown as provided with helical channels 3 and the confronting surface of the shell or sleeve 10 is smooth, the channels may be formed in the shell and the surface of the core may be smooth.

The shell or sleeve 10 is formed of steel or steel alloy, or may be formed of copper-bearing alloys, or other alloys having high heat conductivity, yet is capable of withstanding at its surface the temperature shock of the molten metal. In any case, the mass of metal confronting the casting zone is sufficient to absorb the heat necessary to chill and solidify the metal for later transfer of the heat to the coolant.

The rate at which the two rolls approach each other between the point of complete solidification of the ribbon and the plane through the axes of the roll should at least equal the rate at which the metal contracts, so as to maintain the metal ribbon surfaces and the roll surfaces in good heat-transferring relation. In fact, the rate of approach of the rolls may be greater than the rate of contraction of the metal ribbon so that the metal is worked as it issues from betwen the rolls.

The working pressure may be substantial; consequently the thickness of the shell of each roll must be sulficient to bridge the channels 3 without bending. Stated otherwise, reduction in wall thickness of the shell 10 requires corresponding reduction in width of the channels 3. This cannot be compensated for by increase in depth without loss in cooling efiiciency as well as weakening of the ribs due to their increased height. Consequently, if the wall thickness is reduced, the coolant pressure must be correspondingly increased. The length of the roll is also a factor. If relatively narrow ribbons are cast, more extreme conditions may be tolerated than if wide sheets are cast.

For example, a primarily experimental machine having rolls only 8" long has been operated with a shell only ,4 thick, the grooves of which were A x A with lands between. However, the pressure required to force the coolant (water) through these small channels approached the bursting strength of the shell.

If the lengths of the rolls were increased to 3G", for example, the probable minimum thickness would be about A", however, a thickness of /2 would be preferable. In actual tests, 12" diameter, 30" long rolls having a shell thickness of l and grooves Vs" deep x A wide, and with A" lands between, have produced a fully satisfactory product.

While a particular embodiment of this invention has been shown and described, it is not intended to limit the same to the exact details of the construction set forth, and it embraces such changes, modifications, and equivalents of the parts and their formation and arrangement as come within the purview of the appended claims.

What is claimed is:

1. A roll construction for continuously casting metals wherein a pair of said rolls are disposed in parallel relation and form with a molten metal supply nozzle a casting chamber occupying a limited segment of the rolls, the solidified metal being discharged from between the rolls at the upper extremity of the casting chamber, said roll construction comprising: a cylindrical core having a multiplicity of helical coolant channels in its periphery, each helical channel having approximately one complete convolution from end to end of said core, annular passages communicating with the ends of said channels, inlet and outlet means communicating with the axial ends of all of said channels, aid helical coolant channels forming shellsupporting lands therebetween; and a thick wall shell fitted over said core supported by said lands and bridging said helical channels to form the radially outer walls thereof, said shell arranged to eX- tract heat from the metal in said casting chamber and 4 transfer said heat to coolant flowing in said helical passages.

2. A roll construction for continuously casting metals wherein a pair of said rolls are disposed in parallel relation and form with a molten metal supply nozzle a casting chamber occupying a limited segment of the rolls, the solidified metal being discharged from between the rolls at the upper extremity of the casting chamber, said roll construction comprising: a cylindrical roll member, having walls defining a multiplicity of single convolution helical coolant-circulating channels located at a uniform depth from the surface of said roll member and extending between the axial ends thereof, said roll member also having walls adjacent each end defining annular passages communicating with the ends of said channels and means defining coolant inlet and outlet passages communicating with said annular passages, the heat-absorbing capacity of the portions of said roll radially outwardly of said passages being calculated to effect solidification of metal passing through said casting chamber, and said coolant passages having sufiicient coolant capacity to extract the heat absorbed by said radially outer portions of said roll.

3. A heat-extracting roll construction, comprising: a roll member having a'cylindrical outer surface and having walls defining a multiplicity of single convolution helical coolant-circulating channels located at a uniform depth from the surface of the roll member and extending between the axial ends thereof, said roll member also having walls adjacent each end defining annular passages communicating with the ends of said channels, and said roll member also having means defining coolant inlet and outlet passages communicating with said annular passages.

4. A roll construction as set forth in claim 1, wherein: said channels and shell-supporting lands being substantially equal in width and said channels having a width approximately twice their depth, and said shell having a thickness in excess of four times the depth of said channels.

5. A heat-extracting roll construction, comprising: a roll member having a cylindrical outer surface and having walls defining a multiplicity of single convolution helical coolant-circulating channels located at a uniform depth from the surface of the roll member and extending between the axial ends thereof; means for supplying coolant simultaneously to all of said channels at one axial end of said roll; means for withdrawing coolant simultaneously from all of said channels at the other axial end of said roll whereby all of the coolant circulating through said roll makes a single convolution.

References Cited in the file of this patent UNITED STATES PATENTS Re. 21,260 Hazelett Nov. 14, 1939 544,782 Bragg Aug. 20, 1895 1,583,333 Bigum May 4, 1926 1,598,721 Hitchcock Sept. 7, 1926 2,108,070 Low Feb. 15, 1938 2,171,132 Simons Aug. 29, 1939