US3608614A

US3608614A - Support member for casting in continuous casting operation

Info

Publication number: US3608614A
Application number: US714313A
Authority: US
Inventors: Walter Meier; Peter J Koenig
Original assignee: Concast AG
Current assignee: SMS Concast AG
Priority date: 1967-03-22
Filing date: 1968-03-19
Publication date: 1971-09-28
Anticipated expiration: 1988-09-28
Also published as: DE1608340A1; ES352266A1; CH461713A; BE712544A; FR1556869A; GB1185255A

Abstract

In a continuous casting plant, a carrier member is positioned between and supports the casting as it passes from the outlet of the mold to the casting guideway. The carrier member is arranged to move linearly and rotatably in a plane generally normal to the longitudinal path of movement of the casting for adjusting to any uneven cooling within the mold which causes the casting to deflect from its normal path of movement. If uneven cooling exists within the mold, means are provided for displacing the carrier member to correct the uneven cooling condition.

Description

United States Patent Inventors Walter Meier Wintherthur; Peter J. Koenig, Zumikon, both of Switzerland Appl. No. 714,313

Filed Mar. 19,1968

Patented Sept. 28, 1971 Assignee A. G. Concast Zurich, Switzerland Priority Mar. 22, 1967 Switzerland 4243/67 SUPPORT MEMBER FOR CASTING IN CONTINUOUS CASTING OPERATION 3 Claims, 10 Drawing Figs.

U.S. CI. 164/83, 164/28 2 Int. Cl. 822d 11/12 Field of Search 164/82, 83, 282, 28 3 [56] References Cited UNITED STATES PATENTS 3,329,199 7/1967 Easton 164/282 X 3,339,623 9/1967 Rys et a1... 164/283 X 3,397,733 8/1968 Gricol 164/83 X 3 ,447,592 6/1969 Wertli 164/283 Primary Examiner-J. Spencer Overholser Assistant Examiner-John E. Roethel Attorney-McGlew and Toren ABSTRACT: In a continuous casting plant, a carrier member is positioned between and supports the casting as it passes from the outlet of the mold to the casting guideway. The carrier member is arranged to move linearly and rotatably in a plane generally normal to the longitudinal path of movement of the casting for adjusting to any uneven cooling within the mold which causes the casting to deflect from its normal path of movement. If uneven cooling exists within the mold, means are provided for displacing the carrier member to correct the uneven cooling condition.

PATENTEU smmsn 3,698,614

SHEH 2 [If 2 INVEVTOR. WRLTER MQER J. E 9192 m Nib SUPPORT MEMBER FOR CASTING IN CONTINUOUS CASTING OPERATION SUMMARY OF THE INVENTION The invention is directed to a support arrangement for the casting in a continuous casting plant, and, more particularly, to a support member for supporting the casting in its path of travel from the mold to the casting guideway and the support member is movably in a plane transverse to the longitudinal path of travel of the casting.

In continuous casting, a metal in the liquid state is poured into one end of a cooled open-ended mold and is continuously withdrawn from the other end of the mold and cooling of the casting continues as it passes along a guideway. Within the mold, the exterior surface of the casting solidifies forming a thin crust or skin. However, the interior of the casting still contains metal in a molten state. The metal within the interior of the casting exerts a hydrostatic pressure on the solidified exterior layer. To control the tendency of the exterior layer to bulge outwards, it is desirable to provide suitable means for supporting the sides of the casting as it passes from the mold into the guideway. A known arrangement for supporting the casting between the mold and the guideway is attached to the main structure of the continuous casting plant and consists of supporting or guide rollers mounted on carrier members which are arranged to bear against the sides of the casting as it is withdrawn from the mold. In practice, the surfaces which define the interior cavity of the mold, such as the inside lining tube or the plates forming the walls of the mold, tend to distort and change their shape under the considerable thermal stresses to which they are exposed during the casting process. This distortion or deformation also involves a lateral displacement of the surfaces within the mold which define a cross section at the outlet end of the mold. Since the supporting framework for the mold is not exposed to the same high-thermal stresses and as a result does not move in the same fashion, relative displacement occurs between the internal surfaces of the mold and the supporting rollers which are attached to the main structure of framework of the plant. As a result of this relative displacement, the contact pressure between the casing and the surfaces of the mold becomes unevenly distributed about the entire periphery of the casting. Consequently, the cooling effect on the casting within the mold also becomes nonuniform, particularly in the zone of incipient solidification of the outer layer, which within the mold still has very little strength. As a result, the outer layer of the casting may crack with a resultant liquid metal breakthrough. Moreover, when bar material is being continuously cast, the relative displacement may result in castings with rhomboidal cross sections.

In addition, due to the nonuniforrnity in cooling and contact pressure within the mold, the mold itself experiences uneven wear and its useful life may be appreciably shortened.

Therefore, it is the primary object of the present invention to minimize uneven coolingof the casting within the mold in order to avoid any resulting cracks, metal breakthrough, rhomboidal distortion of the casting, and excessive wear of the mold and the like. Accordingly, in the present invention a support or carrier member is provided between the outlet end of the mold and the casting guideway and the carrier member is provided with supporting elements, the relative positions of which are substantially fixed, but the carrier member itself may be freely or controllably movable in at least one direction in a plane transverse to the longitudinal path of movement of the casting.

In a method of operating a continuous casting plant employing the present invention, the carrier member is arranged to controllably move the casting as it leaves the mold to attain a uniform cooling effect on the casting within the mold.

Another object of the invention is to provide a mold which is oscillatable in the direction of the longitudinal path of movement of the casting and in which the distance from the mold to the transversely movable carrier member is maintained fixed.

Another object of the present invention is to provide support means for the carrier member so that it is movable in all directions linearly or rotatably within a plane substantially normal to the longitudinal path of movement of the casting from the mold to the casting guideway.

A further object of the invention is to provide a simple intermediate support for the casting between the mold and the casting guideway which is simple in construction and operation and which effectively regulates uniform cooling of the casting within the mold.

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 are illustrated and described preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is an elevational sectional view of a vertically arranged continuous casting plant embodying the present invention;

FIG. 2 is a transverse sectional view of the support member disposed between the mold and the casting guideway taken along line IIII in FIG. 1;

FIG. 3 is another transverse sectional view similar to FIG. 2 showing an alternate embodiment of the supporting rollers within the support member;

FIG. 4 is a schematic representation of the relative displacement in a linear direction of a casting and the outlet from a mold;

FIG. 5 is another schematic illustration similar to that in FIG. 4 but with the mold rotatably displaced relative to the casting;

FIG. 6 is still another schematic representation combining the relative displacements illustrated in FIGS. 4 and 5;

FIG. 7 is an elevational sectional view of a continuous casting plant in which the casting moves along an arcuate path from the mold through the casting guideway;

FIG. 8 is a sectional view of a continuous casting plant similar to the one illustrated in FIG. 7 with the support member at the outlet from the mold arranged to be controllably moved in a rotary direction;

FIG. 9 is a transverse sectional view of the support member taken on line IX-IX in FIG. 8; and

FIG. 10 is a transverse sectional view of the mold shown in FIG. 8 and taken along line X-X.

DETAILED DESCRIPTION OF THE DRAWINGS In FIG. 1, a molten metal, such as steel in a liquid state, is poured from a tundish 1 into the interior 15 of an oscillatable cooled open-ended mold 2. Within the mold, as the casting is cooled, a solidified outer layer is formed. The casting 11 is withdrawn from the mold by means of the rollers 14 and passes from the lower end of the mold into a support or carrier member 7 wherein supporting elements 8 provide support between the mold and the casting guideway 12. The casting guideway is firmly secured to the structural framework of the continuous casting plant and is provided with cooling elements, not shown in the drawings, for continuing the cooling of the casting as it passes through the guideway 12.

While the casting 11 is rigidly supported by the rollers 13 within the guideway 12, the intermediate support is flexible in that the carrier member 7 is mounted in a manner which permits it to move in all directions in a plane disposed transverse ly to the longitudinal path of movement of the casting. The carrier member 7 provides support for the exterior layer of the casting which is still thin as it passes between the mold and the guideway and prevents the exterior layer from any undesirable bulging.

As shown in FIGS. 1 and 2, the supporting elements are rollers which bear against the lateral faces of the casting. As an alternative in FIG. 3, the rollers 21 are mounted in the carrier member 20 for contacting the corners of the casting. The

- roller arrangement disclosed in FIG. 3 is particularly suitable for avoiding rhomboidal distortion of the casting cross section since it constrains the diagonals of the cross section and prevents any change in their length.

The

rollers

8 and 21 can yield in the

carrier members

7 and 20 to an extent limited by a stop. On the one hand, this permits a dummy casting which has a cross section exceeding that of the continuous casting by the amount of shrinkage experienced by the casting, to pass between the rollers without being jammed, whereas, on the other hand, the rollers will retain their relative positions when the carrier member is displaced transversely of the longitudinal path of the casting. Alternatively, the rollers may be replaced by supporting elements in the form of cooling plates mounted within the carrier. Such cooling plates may be provided in combination with rollers arranged to provide a constant clearance gap between the cooling plates and the casting surface within the carrier member.

In the arrangement shown in FIG. 1, the desired transverse movement of the carrier member is afforded by mounting the carrier member on a plurality of balls 9 which rest on a ring or race 10. It is also possible to slidably mount the carrier or it could be suspended in some appropriate way to provide the necessary transverse movement.

As the exterior layer 19 of the casting solidifies within the mold 2, the internal wall surfaces 16, 17 defining the interior cavity of the mold are exposed to changing thermal stresses which cannot be controlled. As a result, these inside walls tend to distort, while at the same time the casting which is being continuously withdrawn from the mold is rigidly supported in its path of movement through the guideway 12. Consequently, one side of the casting may be forced tightly against only one of the wall surfaces of the mold, in which case the cooling effect on the casting will become nonuniform. At the same time, the mold itself will be exposed to uneven wear. By providing a carrier member 7 which is movable in all directions transversely to the longitudinal path of movement of the casting, it permits the casting to be supported between the mold 2 and the guideway 12 and the thermal stresses imposed on the exterior layer 19 of the casting are reduced by increasing the distance between the outlet end of the mold and the entrance into the rigidly supported guideway.

Accordingly, the carrier member 7 affords a flexible support for the casting which avoids the likelihood of any disturbance or rupture in its exterior layer.

In FIG. 4, a casting having a square cross section is illustrated schematically by the square 30 with its center 31 disposed on the longitudinal axis of the casting. As the casting passes through the mold, its interior surfaces may distort and become displaced in the direction indicated by the reference numeral 32. Accordingly, the position of the cross section of the mold at its outlet end is then represented by the square 34. At the mold outlet, the two

squares

30, 34 are coplanar. The transversely movable carrier member 7 enables the casting to be linearly displaced without any loss of support until its cross section coincides with that of the square 34. After having passed through the carrier member, the casting enters the guideway 12 which, since it is rigidly supported on the structural framework of the casting plant, axially aligns the casting with the original position of the mold cross section. However, because of the cooling experienced by the casting between its exit from the mold and its entrance into the guideway 12 as the result of spraying devices, which are not shown in the drawing, the exterior layer of the casting, as it leaves the carrier member, has increased, and as a result is much stronger and it is not as likely to be damaged as it is forced back into alignment within the guideway 12.

In FIG. 5, the square 30 again represents the position of the casting cross section with its center indicated by reference numeral 31 at the outlet end of the mold at a particular instant in the casting operation. It has been found that sometimes the interior surfaces of the mold may undergo distortion during the casting process causing the surfaces to twist rotationally in the direction indicated by the arrows 40 and thus assume a position represented by the square 41. However, since the carrier member is capable of rotating about an axis substantially parallel to the longitudinal axis of the casting, it can be displaced in such a manner to afford support for the casting between the mold and the guideway without disturbing the exterior surface of the casting. If the carrier member were rigidly attached to the structural framework of the plant, as is the casting guideway 12, it would have to remain in the position indicated by the square 30 in FIGS. 4 and 5. This would cause the casting to twist in relationship to the mold walls and the result would be an uneven cooling effect inside the mold and the likelihood of a deformation of the cross section of the casting from a square into a rhombus.

FIG. 6 illustrates a combination of the linear and rotary motions separately illustrated in FIGS. 4 and 5. The initial position of the casting cross section at a given instant is represented by the square 30. Linear displacement is indicated by arrow 50 which shifts the cross section into the position represented by the square 52, the center of the cross section being moved from the position indicated by the reference numeral 51. Simultaneously, the cross section of the casting is turned in the direction indicated by the arrow 53 whereby its final direction is represented by the square 54. The ability of the carrier member to be displaced transversely of the longitudinal path of the casting into any position permits satisfactory support for the casting in its passage between the mold and the guideway without any of the undesirable effects which have been described above. It may be convenient to connect the carrier member 7 to the mold 2 so that the supporting element 8 closest to the outlet end of the mold will remain at a fixed distance from the mold even if the mold is oscillated, as is frequently done. The maintenance of a constant distance between the mold and the carrier member is particularly desirable when the casting rate is high. For example, when casting slabs, the lateral motions of the carrier member and its supporting elements may be controlled by a method which initially establishes the manner in which the casting makes all around contact with the interior surfaces of the mold and then corrects any developing asymmetry in the distribution of contact by appropriate displacement of the carrier member. The manner in which this operation is performed will now be described with reference to FIG. 7 in which the casting travels through the mold, the carrier member and the guideway in a circularly arcuate path.

In FIG. 7, between a mold 62 and a guideway 77, both of which are arranged to provide support for the casting along an arcuate path, a casting 65 is supported by a carrier member 66 having support rollers 67. The rollers 67 are mounted in the carrier so as to retain a constant relative distance. The carrier member is arranged so that it is freely movable in a plane substantially normal to the longitudinal axis of the casting. The mold 62 is mounted on the end ofa lever which is arranged to oscillate the mold in the direction of travel of the casting.

Extending from one side of the carrier 66 is a pin which is slidably positioned in a bearing member 84 secured to the framework of the mold by means of bolts 83. On its opposite side, the carrier member is secured to the piston rod of a piston 68 disposed within a cylinder 69 connected to the framework of the mold by a bracket 88. By means of the support arrangement, the carrier member oscillates with the mold 62 and the distance between the mold and the carrier member remains constant. In large-sized plants, the carrier member may be movably mounted in the structure of the casting plant as such.

The interior of the mold is bounded by

plates

86, 87 which are cooled by two separate cooling chambers 89, 91, respectively. On the longer radius side of the mold, remote from the lever fulcrum, the coolant enters the chamber 89 through inlet 63 and exits through outlet 64. On the inside of the curved path of the casting, the coolant enters the chamber 91 through inlet 90 and exits through outlet 92. If the casting inside the mold ceases to make uniform all-round contact with the walls of the mold, for instance because of uneven shrinkage of the solidifying layer of the casting or because of asymmetrical distortion of the

plates

86, 87, then the surface of the casting may lift away from the shorter radius side of the mold before it separates from the longer radius side.

In FIG 7 it is assumed that the casting 65 first loses contact with the inside wall 87 at reference numeral 75 and then with the opposite wall 86 at a slightly lower level or position indicated by the reference numeral 74. Accordingly, the casting remains in contact with the wall 86 for a longer period of time and more heat is lost to the cooling chamber 89 than to the cooling chamber 91. This difference in heat loss can be detected by suitable measuring instruments. The heat loss signals obtained from the two cooling chambers are compared and the resultant difference signal can be employed to control the movements of the carrier member 66 until the inequality in the surface contact of the casting with the interior of the mold is corrected and the two points of separation of the casting from the surfaces of the mold, indicated by the reference numerals 74 and 75, are disposed in the same horizontal plane. The movement of the carrier member transversely to the longitudinal path of travel of the casting results in a change in the cooling rates within the mold until they are the same around the circumference of the casting.

In the illustrated example, the piston 68 is intermittently displaced at short intervals of time until the rate at which heat is abstracted from the sides of the casting is equal. At this point, the error signal will discontinue and the correcting action will cease.

Since in arcuate continuous casting plants the two curved sides of the casting may be differentially cooled for purely geometrical reasons, the movement of the carrier member may be controlled to maintain a largercontact area between the casting and one side of the mold, say the wall 87, than with the other wall, thereby cooling the casting more on one side than on the other. Since secondary cooling outside the mold on the inside of the arc is in such a case less, nonuniformity in the progress solidification is compensated.

As an alternative, it would, of course, also be possible visually to compare the indicated rates of heat loss within the cooling chambers and then manually adjust the carrier by a lead screw or similar means.

Another example of control means for moving the carrier is illustrated in FIGS. 8, 9 and 10. In FIG. 8, metal in a liquid state is poured into an arcuately curved mold 198. Disposed between the mold 198 and a casting guideway, not shown in the drawings, is a carrier member 193 for supporting the casting by means of supporting elements 194. The carrier member 193 is rotatably mounted on balls 195 in a cage or race 196. In turn, the cage 196 is mounted on a ball bearing 197 which permits movement of the carrier member in the direction of the arrows 209, see FIG. 9, and which rests on a track member 199 attached to the structural framework 207 of the continuous casting plant.

As shown in FIG. 10, the cooling chamber 190 of the mold 198 is subdivided into a plurality of separate axially extending cooling

channels

211 and 218 distributed around the circumference of the casting.

Due to the manner in which the carrier member 193 is mounted between the mold and the guideway, it may be controllably rotated and at the same time is free to move linearly in all directions in a plane transverse to the longitudinal path of the casting. The rotary movement of the carrier member is generated by a piston 202 which engages an arm secured to and extending outwardly from the carrier member 193, see FIG. 9. The piston 202 operates in a cylinder 208 which is rigidly secured to the structural framework 207 of the plant. If

it is found that the rate of heat transfer to the two

chambers bers

213 and 217, this would indicate that the circumferential surface of the casting has ceased to bear uniformly against the

interior walls

192, 193 of the mold, and, more particularly that contact pressure against the wall in the zones of the cooling

chambers

211 and 215 is greater while the casting tends to lift away from the

mold walls

191, 192 in the zone cooled by the

chambers

213, 217, respectively. The resultant differences in the rate of heat abstraction can be corrected by conventional means for controlling the position of the piston 202 and the resultant rotational movement of the carrier member 193.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. A method of continuously casting molten metal comprising the steps of continuously pouring molten metal into an open end mold, cooling the molten metal within the mold to form a casting having a molten metal interior and a solidified exterior layer, continuously withdrawing the casting from the mold and supporting and cooling it along a longitudinal path of movement after it has left the mold, and wherein the improvement comprises the steps of providing an arcuately curved path for the casting through the mold and along its longitudinal path of movement after it exits from the mold, forming a plurality of independent cooling chambers within the mold with the cooling chambers extending in the direction of travel of the casting and being distributed around the circumference of the mold, supporting the casting at its exit from the outlet of the mold, measuring the rate of heat removed from the individual cooling chambers within the mold, and, in response to uneven heat removal within the mold, controllably displacing the casting within the mold by moving the casting at the location of its support at the outlet from the mold in a direction transverse to its longitudinal path of movement based on the measured variations of heat transfer rates within the cooling chambers for uniformly cooling the casting within the mold.

2. A method, as set forth in claim 1, characterized by controlling the movements of the casting exteriorly of the mold in the direction transverse to its longitudinal path of movement for correcting nonuniform contact between the casting and the arcuately curved internal walls of the mold.

3. A method of continuously casting molten metal comprising the steps of continuously pouring molten metal into an open end mold, cooling the molten metal within the mold to form a casting having a molten metal interior and a solidified exterior layer, continuously withdrawing the casting from the mold and supporting and cooling it along a longitudinal path of movement after it has left the mold, and wherein the improvement comprises the steps of forming a plurality of independent cooling chambers within the mold with the cooling chambers extending in the direction of the longitudinal path of movement of the casting and being distributed about the circumference of the mold, measuring the rate at which heat is transferred into the cooling chambers from the casting passing through the mold, supporting the casting at its exit from the outlet of the mold and, at the location of its support at the outlet from the mold, moving the location of its support at the outlet from the mold, moving the casting in a direction transverse to the longitudinal path of movement of the casting for varying the cooling rates about the circumference of the casting inside the mold, and controlling the movement of the casting transverse to its longitudinal path of movement in response to the uneven heat removal within the independent cooling chambers for uniformly cooling the casting.

Claims

3. A method of continuously casting molten metal comprising the steps of continuously pouring molten metal into an open end mold, cooling the molten metal within the mold to form a casting having a molten metal interior and a solidified exterior layer, continuously withdrawing the casting from the mold and supporting and cooling it along a longitudinal path of movement after it has left the mold, and wherein the improvement comprises the steps of forming a plurality of independent cooling chambers within the mold with the cooling chambers extending in the direction of the longitudinal path of movement of the casting and being distributed about the circumference of the mold, measuring the rate at which heat is transferred into the cooling chambers from the casting passing through the mold, supporting the casting at its exit from the outlet of the mold and, at the location of its support at the outlet from the mold, moving the casting in a direction transverse to the longitudinal path of movement of the casting for varying the cooling rates about the circumference of the casting inside the mold, and controlling the movement of the casting transverse to its longitudinal path of movement in response to the uneven heat removal within the independent cooling chambers for uniformly cooling the casting.