EP1175947A1

EP1175947A1 - End wall for continuous caster mold

Info

Publication number: EP1175947A1
Application number: EP01306470A
Authority: EP
Inventors: Larry T. Birkner
Original assignee: Acme Steel Inc
Current assignee: Acme Steel Inc
Priority date: 2000-07-28
Filing date: 2001-07-27
Publication date: 2002-01-30

Abstract

An end wall for a continuous caster and method of extending the service life thereof. End walls (10) made of copper are typically used in the molds of continuous casters. The end walls wear more heavily at their lower sections because the cooling effects of the end walls on the molten material result in more abrasion at the lower sections. An end wall which can be reversibly mounted has the advantage of substantially extending the service life of the end wall.

Description

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to a mold used in a continuous caster. In particular, the invention relates to a mold design in which the service life of the end walls is substantially improved.
The use of continuous casters to make sheet steel is well known. The thin slab continuous casting process was developed several years ago (approximately 10 to 12) as an evolution of thick slab casting. In recent years, the market for sheet steel made by continuous casting processes has become highly competitive. Competition has required manufacturers to improve the efficiency of their operations and extend the service life of their equipment wherever possible.
In a continuous casting mold, molten steel is poured into a vertically oriented chamber in which the walls of the chamber are made of a material with high thermal conductance, such as copper or copper alloy. As the molten metal passes through the mold, the surface of the molten metal partially solidifies so that the material emerging from the bottom of the mold can be handled and further processed into sheet form. The solidification of the molten metal as it passes through the mold results in higher amounts of wear in the lower portions of the mold where the molten metal is more solid than at upper portions of the mold. As a result, the copper or copper alloy surfaces of the mold wear out more quickly at the lower end of the mold than at the upper end. Periodically, it is necessary to refurbish the walls of the mold by removing the face plates and end walls and machining them so that the copper surfaces of the mold components are smooth and able to efficiently remove heat from the molten steel as it passes through the mold.
Examples of patents in which continuous casters are used include the following U.S. Patents: No. 4,953,614 (Lemper), which shows a mold 39 used in conjunction with a tundish 20 in a series of rolls used to form sheet steel; No. 5,467,810 (Grove), which shows a continuous casting mold with copper facing plates and end walls which are water cooled.
The present invention is embodied in a mold for a continuous caster in which the end walls are designed so that they can be mounted in either of two alternative vertical orientations. The design allows the end walls of a continuous casting mold to be switched end-to-end in order to maximize the service life of the end walls.
The features and advantages of the present invention will become more apparent upon a reading of the following detailed descriptions read in conjunction with the accompany drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a perspective view of a typical continuous casting mold in which the present invention has application;
Figure 2 is a cross-sectional view of an end wall assembly of the prior art;
Figure 3 is a longitudinal cross-section of an end wall carrier used in accordance with the present invention;
Figure 4 is a front elevational view of the end wall carriers shown in Figures 2 and 3;
Figure 5 is a cross-section of an end wall of the present invention
Figure 6 is a rear elevational view of an end wall of the present invention;
Figure 7 is a schematic diagram showing the first step in a way of machining an end wall in accordance with the present invention;
Figure 8 is a schematic diagram showing a mounting orientation for an end wall made in accordance with the present invention;
Figure 9 is a schematic diagram showing the second step in a way of machining an end wall in accordance with the present invention;
Figure 10 is a schematic diagram showing an alternative mounting orientation for an end wall made in accordance with the present invention; and

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 shows a mold frame 1 with a coolant path 2. Each side of the mold frame 1 has a broad face plate 3 carried by face plate carriers 4. The face plates 3 and face plate carriers 4 are spaced to form a cavity or chamber 5 into which molten steel is poured. Steel in thin slab form with a still molten core exits through the lower portion of the mold frame 1. As the slab moves away from the mold its skin becomes increasingly hardened as the slab cools. End walls 10 are disposed between the broad face plates 3 at the sides of the face plates 3. The end walls 10 are carried by end wall carriers 7.
Figure 2 shows an end wall carrier 7 pivotably mounted to a support 8. The end wall 10a is an example of a prior art end wall mountable to the end wall support in only one position, the position shown in Figure 2. In operation, it is important that the hot face 25 of the end wall 10a be substantially vertical. Vertical alignment is important so that the slab made with the mold is aligned with the rollers through which the slab passes later in the process. The vertical alignment of the end wall 10a is adjustable by operation of the screw and nut mechanism 9, which allows the upper part of the end wall carrier 7 to pivot about the upper pivot support 40, while the lower part of the end wall carrier 7 moves to the left or right as shown in Figure 2, and the lower part of the end wall carrier 7 pivots about the lower pivot support 41.
As can also be seen in Figure 2, seven bolts 11 are used to hold the end wall 10a to the end wall carrier 7. The bolts 11 extend through bolt holes 13 which run from the rear (or left side in Figure 2) of the carrier 7 through the carrier 7 and into the connection holes 24 in the mounting face of the end wall 10a. The carrier 7 and end wall 10a are prevented from slipping vertically relative to one another by an upper round key 17. The lower oblong key 15 prevents horizontal relative motion (i.e., slipping). In addition, the temperature of the end wall 10a is monitored by two thermocouples which extend through the thermocouple passageways 19 and 21 in the upper portion of the end wall carriers 7 and into the mounting face 23 of the end wall 10a. The thermocouples extend into thermocouple openings 29 and 31 in the upper portion of the mounting face 23 and the end wall 10a, when the end wall is mounted in a first vertical orientation. However, when the vertically interchangeable end wall 10 (shown in Figures 5 and 6) is mounted in an opposite or alternative orientation, for example after a machining in accordance with the invention, the thermocouple passageways 19 and 21 will align with openings the 39 and 41, and the thermocouples will, alternatively, extend into openings 39 and 41 (See Figure 6).
Figures 3 and 4 show an end wall carrier 7 to which an end wall 10 of the present invention may be mounted. The end wall carrier several (a total of seven holes shown in Figures 3 and 4) bolt holes 13 which allow the carrier 7 to be bolted firmly to a support 8 (as shown in Figure 2). To allow thermocouples to reach and extend into the end wall 10, the carrier 7 has two thermocouple guideways 33 and 34 which extend from the side of the end wall carrier 7 to the outer face 35 of the carrier 7 to which the end wall 10 may be mounted. The carrier 7 has an upper round key location 17 and a lower oblong key location 15. Upper and lower fluid pathways 47 and 48, respectively, allow the coolant to be passed through the carrier 7 and to the end wall 10 mounted thereto.
Figures 5 and 6 show an end wall 10 made in accordance with the present invention. The end wall 10 includes a first round key recess 18 and a second round key recess 20, which are equidistant from the neutral axis 12. Similarly, the end wall 10 includes a first oblong recess 14 and a second oblong recess 16, which are also equidistant from the neutral axis 12. Finally, the end wall 10 includes a first set of thermocouple recesses 29 and 31 and a second set of thermocouple recesses 39 and 41, the sets being equidistant from the neutral axis 12. A series of lateral strain relief notches 22 are disposed along the mounting face 23 of the end wall 10. The seven connection holes 24 are also symmetrical about the neutral axis 12. The end wall 10 of the present invention has an upper area, above the neutral axis 12, which is the mirror image of the lower area of the end wall below the neutral axis.
The symmetrical arrangement of the oblong key slots 14 and 16, the round key holes 18 and 20, and the thermocouple openings 29, 31, 39 and 41, is such that the end wall 10 can be mounted to the end wall carrier 7 in either of two vertical orientations. This flexibility of attachment allows the end wall 10 to be machined in such a way as to extend its service life. In particular, when the end wall 10 has been used to the point where it is in need of refurbishment, it can be removed from the carrier 7 and placed in a machine tool on an angle so that more material can be removed from one end (i.e., the worn end, typically the lower end) of the end wall 10 than from another, and the end wall 10 can be re-mounted in position on the end wall carrier 7 so that the end of the end wall 10, having more material remaining on the hot face 25 can be placed at the lower end of the end wall carrier 7. While the work face or hot face 25 of the end wall may not be perfectly parallel to the mounting face 23 of the end wall 10 after refurbishment (see Figure 7), such deviations from parallel can be accomodated by adjustment of the end wall carrier 7 by operation of the screw and nut arrangement 9. In a second refurbishment, the hot face 25 and the mounting face 23 will, by the same assymetric machining operation, be brought more closely into parallel relationship (see Figures 8 and 9). Openings 49 and 50 at the ends of the mounting frame 23 align with the fluid pathways 47 and 48 to allow cooling fluid to flow through the end wall 10. The notches 22 in the mounting face 23 are preferably symmetrically disposed along the face 23 about the neutral axis 12.
It should be noted that the thermocouple opening 39 overlaps with the oblong key slot 16 as shown in Figure 6. The overlap results from the fact that the end wall 10 shown in Figures 5 and 6 is intended for a standard end wall carrier 7 shown in Figures 2, 3 and 4, an end wall carrier not initially designed to receive an end wall mounted in alternating vertical orientation after refurbishments. However, if end wall carriers of the type generally shown in those figures were to be designed to receive an end wall which was intended to be inverted after each refurbishment, it would be preferable to locate the various surface features so that there would be no overlapping, such as that which exists between the key slot 16 and the thermocouple passageway 39.
Figures 7 through 10 show how the service life of an end wall embodying the present invention can be substantially improved. The method of the present invention entails the removal of less material from one end of an end wall than the other each time refurbishment of the end wall is performed. For example, as shown in Figure 6, after an end wall has been used to the point where it needs refurbishment, it can be removed and mounted in a support 54 where it may be machined on an angle 50. The upper or less worn end A of the end wall will have substantially less material removed than the lower end B of the end wall. Thus, in Figure 6, the material to be removed 52 from end B of the end wall 10 is greater than the amount of material removed from end A. In this machining operation, only as much material is removed as is needed to create a smooth surface, regardless of whether the hot face 25 is parallel to the mounting face 23. By using this technique, very little material needs to be machined from the less worn end of the end wall (i.e., end A in Figure 7 and end B in Figure 9). The non-parallel condition of the faces 23 and 25 can be accomodated by lateral adjustment of the thicker end A of the end wall 10 and of the lower end of the end wall carrier 7, as is shown in Figure 7. This adjustment is achieved by operation of the screw and nut assembly 9, as shown in Figure 2.
When the end wall, as oriented in Figure 8, is again in need of refurbishment, the end wall can be removed and again machined in an assymetric manner, i.e., at an angle 51 as shown in Figure 9. The material to be removed in the second machining 54 is greater at end A of the end wall 10, as shown in Figure 9. This procedure may be used as an alternative to machining the end wall 10 in such a manner whereby the work face 25 and the mounting face 23 are maintained in a parallel relationship, as has been the common practice. As a result, the service life of an end wall may be greatly improved, perhaps as much as doubled. End walls are expensive components and substantially increasing the service life of such a component can result in substantial savings to the operator of a continuous caster.
The steps illustrated in Figures 6 through 9 indicate that the end wall 10 could be used in three orientations or three wear cycles, i.e., first, with end A at the upper end of the mold and end B at the lower end (not shown); second, with end B up and end A down (see Figure 7); and third, with end A up and end B down. However, there may be more than three cycles available, depending upon the thickness of the hot face of the end wall, upon the toughness of the alloy used to form the end wall, and upon other factors. It should also be noted that the angles 50 and 51 of machining shown in Figures 6 and 8 are not to scale. A typical machining of an end wall requires removal of only a few millimeters of the hot face at the lower end, and fractional millimeters, if any, need to be removed from the upper end.
The foregoing detailed description is a description of only one example or embodiment of the present invention. It will be understood by those of skill in the art that this invention may be practiced in a number of alternative embodiments in which variations and modifications from the embodiment shown and described herein nevertheless embody the spirit and scope of the appended claims.

Claims

A heat transfer and containment component of a mold for use in continuous casting of steel comprising: a pair of opposing, spaced-apart face plates, and a pair of opposing spaced-apart end walls, each of said end walls being carried by an end wall mount, each of said end walls and said end wall mounts having mating surfaces abutting one another when an end wall is mounted to a mount by which it is carried, said mating surfaces having symmetrical surface features located such that an end wall may be mounted with either of its ends adjacent to either end of the mount by which it is carried.
A component in accordance with claim 1 wherein:
said end wall mating surface has a transverse neutral axis with upper surface configurations above said neutral axis and lower surface configurations below said neutral axis, said upper and lower surface configurations being mirror images of each other.
A component in accordance with claim 1 wherein:
said end wall has at least one fluid passageway extending lengthwise within said end wall, said passageway having a first port at a first end of said end wall and a second port at a second end of said end wall, said mount having a first key location on an upper half of said mounting surface and a second key location on a lower half of said mounting surface, said end wall having two first key receiving notches, each of said key receiving notches being alignable with said first key location on said mount, said end wall having two second key receiving notches, each of said second key receiving notches being alignable with said second key location on said mount, whereby said end wall is capable of being mounted to said mount in either of two positions.
A component in accordance with claim 3 wherein:
said first key location on said mount includes a round recess for receiving cylindrical key, said end wall having a primary round key receiving notch on one side of said end wall, and a secondary round key receiving notch on an opposite side of said end wall, each of said primary and secondary round key receiving notches on said end wall being alignable with said round recess on said mount.
A component in accordance with claim 4 wherein:
said second key location on said mount includes an oblong recess for receiving a flat oblong key, said end wall having a primary flat key receiving notch on one side of said end wall, and a secondary flat key receiving notch on an opposite side of said end wall, each of said primary and secondary flat key receiving notches being alignable with said oblong recess on said mount.
A component in accordance with claim 5 wherein:
said mount includes at least one thermocouple access opening on an upper end of said mount, said end wall having at least one corresponding thermocouple recess, at least one said thermocouple recess aligning with at least one said thermocouple access opening on said mount when said end wall is mounted to said mount in a first position, and a second thermocouple recess aligning with said thermocouple access opening where said end wall is mounted to said mount in a second position.
A method of operating a mold of claim 1 wherein said end wall is first mounted to said mount in a first orientation with a first side of said end wall being attached to an upper end of said mount and a second side of said end wall being attached to a lower end of said mount, using said mold until said end wall is in need of refurbishment, removing said end wall and machining a work contacting edge of said end wall, more material being machined away from said second side of said end wall than from said first side of said end wall, mounting said end wall to said mount in a second orientation with said second side of said end wall being attached to an upper end of said mount and said first side of end wall being attached to said lower end of said mount.
A method in accordance with claim 7 wherein:
said end wall is used in its second orientation until said end wall is in need of a second refurbishment, removing said end wall a second time and machining said work contacting edge a second time, in said second machining more material being removed from said first side of said end wall than from said second side, remounting said end wall to said mount in said first orientation.
An end wall for a continuous casting mold comprising: an elongated end wall body with a mounting face and oppositely directed work face, said mounting face having a plurality of recesses and a first fluid pathway port on a first end of said end wall, and a second fluid pathway port at a second end of said end wall, said plurality of recesses including at least one piece of mounting key openings, said openings of said pair being substantially similar in size and shape, a first one of said pair being spaced from said first end of said end wall a predetermined distance, a second one of said pair being spaced from said second end of said end wall by a second predetermined distance, said first and second distances being equal.
An end wall in accordance with claim 9 wherein:
said plurality of recesses includes additional pairs of recesses, each one of said additional pairs being comprised of a first recess which is substantially similar in size and shape to a second recess of said pair, and said pairs each being symmetrically disposed on said mounting surface with respect to a point on said mounting surface midway between said ends of said end wall.