US3756304A

US3756304A - Method and apparatus for guiding continuously cast strip

Info

Publication number: US3756304A
Application number: US00243276A
Authority: US
Inventors: C Gerding
Original assignee: Jones and Laughlin Steel Corp
Current assignee: Ltv Steel Co Inc; Jones and Laughlin Steel Inc
Priority date: 1972-04-12
Filing date: 1972-04-12
Publication date: 1973-09-04
Anticipated expiration: 1990-09-04
Also published as: CA976723A; GB1421185A; FR2179755B1; DE2315306A1; FR2179755A1; IT981901B; JPS4916622A; JPS5813261B2

Abstract

Method and apparatus for guiding metal strip continuously cast on the inside surface of a rotating ring through an open end thereof with minimum twisting comprises a plurality of pairs of guide rolls positioned and adjusted to cause the strip to travel in a spiral path of decreasing curvature on the surface of an imaginary cone, the axis of which passes through the ring.

Description

United States Patent 1 191 Gerding 1 Sept. 4, 1973 [54] METHOD AND APPARATUS FOR GUIDING 2,450,428 10/1948 Hazelett 164/277 ONT CAST STRIP 2,477,030 7/1949 Wuetig 164/84 X [75] Inventor: Charles Christian Gerding, FOREIGN PATENTS OR APPLICATIONS Pittsburgh, Pa. 528,359 7/1956 Canada 164/87 22,943 8/1910 Great Britain.... 164/276 [731 Asslgneel Jflmes & Steel Corporal, 1,177,758 1/1970 Great Britain 164/87 Pittsburgh, Pa. 22 p Apt 2 19 2 Primary Examiner-R. Spencer Annear Att0rney-G. R. Harris and T. A. Zalenski [21] Appl. No.2 243,276

[57] ABSTRACT [52] U.S. Cl 164/87, 164/276, 164/282 Method and apparatus for guiding metal strip continu- [51] Int. Cl 822d 11/12 ously cast on the inside surface of a rotating ring [58] Field of Search 164/87, 276, 277, through an open end thereof with minimum twisting 164/282 comprises a plurality of pairs of guide rolls positioned and adjusted to cause the strip to travel in a spiral path [56] References Cited of decreasing curvature on the surface of an imaginary UNITED STATES PATENTS l-lazelett .1 164/277 X cone, the axis of which passes through the ring.

21 Claims, 3 Drawing Figures METHOD AND APPARATUS FOR GUIDING CONTINUOUSLY CAST STRIP This invention relates to a method and apparatus for guiding metal strip continuously cast on the inside surface of a rotating ring. It is more particularly concerned with an apparatus for guiding such strip out of the ring with minimum deformation of the cast strip.

It is known to cast metal strip continuously on the inside surface of a ring or drum which is rotated about its axis. Apparatus intended for casting flat strip in this way is disclosed in I-Iazelett US. Pat. No. 2,383,310 of Aug. 24, 1945. Apparatus intended for casting strip of channel-shaped cross-section in this way is disclosed in I-Iazelett US. Pat. No. 2,450,428 of Oct. 5, 1948. The first mentioned patent says that the solidified strip can be spiraled out through an open end of the ring but neither describes nor illustrates apparatus therefor. It shows only apparatus for coiling the strip within the circumference of the ring, which presupposes a ring of rather large diameter. Such an arrangement would allow the strip to cool in coil form, which would make straightening difficult, and would necessitate interruption of continuous casting to remove the coiled strip.

The principal problem in leading out strip through an end of the ring is to do so without excessive localized distortion of the cast metal. Although the strip is, of course, hot and can be bent to some extent without damage, its cast structure, particularly just as it separates from the ring, can tolerate deformation only at a very limited rate.

The natural tendency of the cast strip as it separates from the ring is to fall away by its own weight, bending most severely at the region of separation where it is weakest. This bending, if uncontrolled, will occur around a radius much smaller than is necessary or desirable for eductionof the strip from the ring. Even minor external mechanical forces, such as those resulting from the pull of pinch rolls, likewise tend to concentrate the bending deformation at the weakest region of the strip. Scrapers, where used, tend to do the same thing. Furthermore, any force applied outside the ring to lead the strip out of the ring tends to twist the strip, principally in its weakest region.

It is an object of my invention, therefore, to provide a method and apparatus for continuously leading strip continuously cast on the inside of a ring out of an end of the ring with minimum bending and twisting deformation of the strip. It is another object to provide such apparatus adapted to guide channel-shaped strip. It is still another object to provide apparatus as above mentioned through which the strip is easily threaded. Other objects will appear in the course of the description of my invention which follows.

7 I have invented a method and apparatus for guiding continuously cast strip out throughthe end of the casting ring which minimizes localized deformation, both bending and twisting. My apparatus decreases unequally the curvatures of the two sides of the strip and so guides the solidified strip from the ring into a spiral path of gradually decreasing curvature or increasing radius on the surface of an imaginary cone. After the strip has cleared the ring, my apparatus equalizes the curvatures of the two sides of the strip, so that it is traveling in a helical path, from which it can be flattened to a horizontal plane.

My invention will be more readily understood by reference to the attached figures which illustrate an embodiment thereof presently preferred by me.

FIG. 1 is a perspective view of my apparatus, a portion of which is broken away, illustrating its essential features. 7

FIG. 2 is an end elevation ofa guide unit of my apparatus comprising a guide roll pair and its mounting.

FIG. 3 is an elevation in cross-section of the apparatus of FIG. 2 taken on the plane 3-3 thereof.

In the figures, the strip 10 is solidified between the inner surface 11 of a casting ring 12 and the outer surface 13 of a roll 14 which is positioned within ring 12 near its lowermost point. Ring 12 is caused to rotate in a clockwise direction as seen in FIG. 1 by means not shown, and its outside surface is cooled by means such as water sprays, also not shown, so as to extract heat from its inside surface 11. Likewise, a cooling medium is circulated through roll 14 so as to extract heat from its outside surface 13. Molten metal is supplied to the bottom portion of the ring 12 through flanges launder 15. Ring 12 is formed with inwardly directed inclined flanges 16 on each side so that a pool of metal is contained therebetween in its lowermost portion. Roll 14 is formed with beveled ends 17 which mate with fanges 16 so that the solidified strip 10 is of channel-shaped cross-section.

The strip 10 solidified between ring 12 and roll 13 has approximately the same curvature as inside surface 11 of ring 12, which, of course, is cylindrical. In order to get it out through the open end of ring 12, its curvature must be increased and it must be caused to move axially of ring 12. These changes in its path are brought about by passing it through successively positioned guide means or units to be described. These units are shown in perspective in FIG. 1 and in more detail in FIGS. 2 and 3.

The first guide unit 18 encountered by strip 10 as it is separated from ring 12 comprises an elongated mounting 27 from one face of which project parallel spindles 21 and 22 at its opposite ends. Spindle 21 carries a freely rotatable roll 23 formed with outwardly projecting inclined flanges 24 at each end in the same manner and shape as inside surface 11 of ring 12. Spindle 22 carries a freely rotatable roll 25 having beveled ends 26 in the same manner and shape as the outside surface 13 of roll 14. From the opposite face of mounting 27 projects a shaft 28 joumaled in a plate 29 and passing through that plate. Shaft 28 is positioned with its axis intermediate the axes of

spindles

21 and 22, but nearer the axis of spindle 21 than that of spindle 22. The projecting end of shaft 28 carries a radially extending crank arm 30. Attached to plate 29 on the same side thereof as crank arm 30 is bracket 31 in which is joumaled a trunnion ring 32 which holds a double- 'ended air cylinder 33 at one end thereof. The piston rod 34 of air cylinder 33 is attached to crank arm 30 by pivot pin 35. Compressed air from a source not shown is introduced into the trunnion end of air cylinder 33 through air line 37 and compressed air from the same'source is introduced into the opposite end of air cylinder 33 through air line 38. Those air lines are connected to a four-way valve, not shown, by means of which the air can be supplied to either end of the air cylinder as desired.

Guide unit 18 is positioned inside ring 12 with roll 23 between the inside surface 11 of ring 12 and the path of separated cast strip 10. Roll 25 is on the opposite side of cast strip 10. The guide unit 18 is positioned so as to bend the cast strip inwardly and increase its curvature. Unit 18 is also positioned so that the increase in curvature of strip 10 on its side adjacent the exit end of ring 12 is somewhat less than the increase in curvature of the strip on its other side. The second and

third guide units

19 and 20 respectively are of the same construction as guide unit 18. The three

units

18, 19 and 20, each of which is at least partially inside ring 12, are positioned so that the portions of the successive units which are inside the ring are successively smaller. They are likewise positioned so that the path they impart to the strip 10 is a spiral around an imaginary cone, the axis of which passes through ring 12. Diametrically opposite elements of this imaginary cone are shown as dotted

lines

40 and 41 in FIG. 1. The apex angle of the cone is only a few degrees and, as shown in FIG. 1, the base of the imaginary cone adjoins the exit end of ring 12. Element 40 is the first element of the cone of evolution encountered by the strip. It lies near to the inside surface 11 of ring 12 and lies on the surface of strip 10 shortly after its separation from ring 12 but is not at right angles to the edges of strip 10 by a few degrees.

The guide units l8, l9 and 20 previously mentioned are all positioned at least partially within the upper half of ring 12. The curvature imparted to the strip by those units causes it to continue to travel through a further angular distance bringing it around into an approximately horizontal plane at or near the lowermost portion of ring 12. Pinch rolls 43 and 44 disposed above and below the strip path are positioned near the lowermost portion of ring 12 so as to equalize gradually the curvatures of the two edges of the strip and change the path of travel of strip 10 gradually from a spiral on an imaginary cone to a circle. At the same time they decrease those equalized curvatures to zero, if desired, so as to produce strip the central portion of which is flat. Those pinch rolls are driven by means not shown.

The

guide units

18, 19 and 20 are mounted on a framework, not shown, which projects into the open end of ring 12 opposite the end from which the strip 10 is lead out. The

individual units

18, 19 and 20 are attached to this framework by affixing their respective mounting plates 29 to the framework at the angles required to guide the strip as has been described above. For this purpose, the framework or the mounting plates are provided with conventional adjusting means, such as adjusting screws, not shown.

At the commencement of operations of my apparatus, the

rolls

23 and 25 of each unit l8, l9 and 20 are set so that the plane common to their parallel axes is more or less at right angles to the strip path. This provides a gap between

rolls

23 and 25 to maximum width. The rolls are set in this position by admitting air to air cylinder 33 through air line 37. A dummy or starter strip approximately equal in width to strip 10 to be cast but somewhat thinner is placed with one end in ring 12 at its lowermost portion and is trained under roll 14 and through

units

18, 19 and 20 and pinch rolls 43 and 44. Molten metal is then led into the lowermost portion of ring 12 through launder and ring 12 is caused to rotate. Pinch rolls 43 and 44 are likewise started up. The first molten metal solidified between ring 12 and roll 14 freezes to the end of the dummy strip and is lead around through the guide units thereby. When solidified strip 10 is in the guide units air is admitted to air line 38 and allowed to exhaust through air line 37 so causing piston rod 34 to move to the right in FIG. 2 and rotate

rolls

23 and 25 into their position of minimum gap as shown in FIG. 1. The centerline of shaft 28 is spaced from roll 23 a distance of a little more than the thickness of cast strip 10, so that rotating shaft 28 to open or close the gap between

rolls

23 and 25 does not greatly alter the upper limit of the strip path.

As I have mentioned, the apex angle of the imaginary cone is small and desirably is as small as possible. Its minimum value is dependent on the relation between the width of the cast strip and the inside diameter of the ring through which it must be led out. I have constructed successful apparatus with values of this angle between about 6 and about 15.

It is also desirable to keep the angular path of travel of the strip on the imaginary cone as short as possible, as the angular range over which the strip will lie in full contact with a conical surface is limited. This range depends on the apex angle of the cone. It is generally desirable to bring the strip out more or less horizontally through pinch rolls 43 and 44. As the molten metal pool occupies the bottom portion of the ring 12, roll 13 must be down stream from the metal pool, clockwise in FIG. 1, and the chilled strip separates from ring 12 and roll 13 somewhat down stream of that roll. Thus the available angular path of travel is something less than 360. I find it possible to lead out the strip in the way here disclosed in an angular path of travel as short as about 315.

The path of the strip as it leaves pinch rolls 43 and 44 is not parallel to the vertical plane of the end of ring 12 but is inclined thereto at an angle which depends on the apex angle of the imaginary cone and the angular length of the strip path on the cone.

My apparatus may be modified in accordance with the requirements of the strip being cast. If a large casting ring is employed, it may be desirable to drive one or both of guide rolls 23 and 25 in some or all of the guide units. If very wide strip is to be cast, the apex angle of the cone may be somewhat larger than the values previously mentioned. It may be desirable under some conditions to use fixed auxiliary guides rather than a dummy strip to enter the cast strip into the guide units. Other modifications will occur to those skilled in the art of strip casting.

I claim:

1. Apparatus for guiding metal strip continuously cast on the inside surface of a rotating ring out of the ring through an open end thereof comprising guide means positioned circumferentially of the ring and adjusted to increase gradually the curvature of the strip as it is separated from the ring, the curvature of the inside edge being increased more than the curvature of the outside edge, then to decrease gradually those curvatures so that the strip is caused to travel in a spiral path disposed on the surface of an imaginary cone the axis of which passes through the ring.

2. Apparatus of claim 1 including guide means positioned and adjusted to reduce gradually and equalize those curvatures as the strip passes out of the ring.

3. Apparatus of claim 1 including guide means positioned and adjusted to reduce the curvature of the strip to zero after the strip has passed out of the ring.

4. Apparatus of claim 1 in which the guide means are positioned and adjusted to lead the strip from contact with the ring surface out of the ring in an angular travel of less than about 360.

5. Apparatus of claim 1 in which the apex angle of the cone is between about 6 and about 6. Apparatus of claim 1 in which an element of the imaginary cone lies on the surface of the strip approximately where it is being separated from the ring.

7. Apparatus of claim 1 in which the guide means comprise a plurality of pairs of rotatable rolls, each pair being mounted with the roll axes parallel to and spaced from each other so that the strip passes between the rolls of a pair.

8. Apparatus of claim 7 including at least three pairs of rolls.

9. Apparatus of claim 7 in which at least the first pair of rolls is positioned at least partially within the rotating ring.

10. Apparatus of claim 7 in which the first and second pairs of rolls are positioned at least partially within the rotating ring, with the second pair being positioned inside the ring to a lesser extent than the first pair.

11. Apparatus of claim 7 in which one guide roll is provided with flanges and the other guide roll is provided with beveled ends.

12. Apparatus of claim 7 in which at least one pair of rolls is cantilevered from a mounting which is adjustable pivotally about an axis parallel to the roll axes and positioned therebetween.

13. Apparatus of claim 12 including remotely controllable means for rotating the mounting about its pivot.

14. Apparatus of claim 12 in which the axis of the mounting pivot is closer to one roll of the pair than it is to the other roll of the pair.

15. Apparatus of claim 14 in which the uppermost roll is closer to the axis of the mounting pivot.

16. A method for removing metal strip continuously cast on the inside surface of a rotating ring from the ring through an open end thereof which comprises separating the strip from the ring, increasing the curvature of the strip as it is separated from the ring in a manner such that the curvature of the strip edge furthest away from said open end of the ring is increased more than the curvature of the strip edge nearest said open end of the ring and gradually decreasing said curvatures so that the strip travels in a spiral path disposed on the surface of an imaginary cone having an axis which passes through the ring 17. The method of claim 16 which includes gradually both reducing and equalizing said curvatures as the strip passes out of the ring.

18. The method of claim 16 which includes reducing the curvature of the strip to zero after the strip has passed out of the ring.

19. The method of claim 16 which includes leading the strip from contact with the ring surface out of the ring in an angular travel of less than about 360.

20. The method of claim 16 in which the apex angle of the imaginary cone is between about 6 and about 15.

21. The method of claim 16 in which an element of the imaginary cone lies on the surface of the strip approximately where it is being separated from the ring.

Claims

4. Apparatus of claim 1 in which the guide means are positioned and adjusted to lead the strip from contact with the ring surface out of the ring in an angular travel of less than about 360* .

5. Apparatus of claim 1 in which the apex angle of the cone is between about 6* and about 15* .

6. Apparatus of claim 1 in which an element of the imaginary cone lies on the surface of the strip approximately where it is being separated from the ring.

8. Apparatus of claim 7 including at least three pairs of rolls.

16. A method for removing metal strip continuously cast on the inside surface of a rotating ring from the ring through an open end thereof which comprises separating the strip from the ring, increasing the curvature of the strip as it is separated from the ring in a manner such that the curvature of the strip edge furthest away from said open end of the ring is increased more than the curvature of the strip edge nearest said open end of the ring and gradually decreasing said curvatures so that the strip travels in a spiral path disposed on the surface of an imaginary cone having an axis which passes through the ring.

17. The method of claim 16 which includes gradually both reducing and equalizing said curvatures as the strip passes out of the ring.

19. The method of claim 16 which includes leading the strip from contact with the ring surface out of the ring in an angular travel of less than about 360* .

20. The method of claim 16 in which the apex angle of the imaginary cone is between about 6* and about 15*.