CA1217314A - Tapered mold liner facing - Google Patents
Tapered mold liner facingInfo
- Publication number
- CA1217314A CA1217314A CA000442040A CA442040A CA1217314A CA 1217314 A CA1217314 A CA 1217314A CA 000442040 A CA000442040 A CA 000442040A CA 442040 A CA442040 A CA 442040A CA 1217314 A CA1217314 A CA 1217314A
- Authority
- CA
- Canada
- Prior art keywords
- mold
- facing
- face
- walls
- liner plate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Abstract
TAPERED MOLD LINER FACING
ABSTRACT OF THE DISCLOSURE
A continuous molten metal casting mold has front, rear and side walls and is open at the top and bottom in a box-like configuration. The mold walls define a cavity therebetween. Each mold wall comprises an outer backing plate, an intermediate liner plate and an interior facing with the interior facing being of a material having a substantially lower thermal conductivity than the material of the liner plate. The backing plate and liner plate are each of constant thickness, in cross-section, from top to bottom. The interior facing gradually increases in thickness, in cross-section, from top to bottom and the mold cavity decreases, in cross-section, from top to bottom. As the metal being cast flows downwardly through the mold and is cooled, the metal which shrinks upon cooling remains in contact with the facing. Furthermore, because of the increased thickness of the facing, the rate of cooling is reduced as the metal travels downwardly through the mold. Consequently, there is a substantial reduction in air gaps between the cooling metal and the mold walls resulting in a cast metal slab having a smoother exterior surface.
ABSTRACT OF THE DISCLOSURE
A continuous molten metal casting mold has front, rear and side walls and is open at the top and bottom in a box-like configuration. The mold walls define a cavity therebetween. Each mold wall comprises an outer backing plate, an intermediate liner plate and an interior facing with the interior facing being of a material having a substantially lower thermal conductivity than the material of the liner plate. The backing plate and liner plate are each of constant thickness, in cross-section, from top to bottom. The interior facing gradually increases in thickness, in cross-section, from top to bottom and the mold cavity decreases, in cross-section, from top to bottom. As the metal being cast flows downwardly through the mold and is cooled, the metal which shrinks upon cooling remains in contact with the facing. Furthermore, because of the increased thickness of the facing, the rate of cooling is reduced as the metal travels downwardly through the mold. Consequently, there is a substantial reduction in air gaps between the cooling metal and the mold walls resulting in a cast metal slab having a smoother exterior surface.
Description
BACKGROUND OF THE INVENTION 121~314 In the process o~ continuously casting steel strands, molten metal is poured into the open upper end o~ a hollow box-like mold. As the molten metal flows downwardly through the mold~ the metal is partiall~ cooled. The partially cooled metal continues to flow downwardly through the open bottom end of the mold in the form of a continuous slab or billet or the like. The molds used in this ~rocess generally comprise spaced apart, parallel front and rear walls and a pair of opposed side walls.
Each of the walls is made of a relatively heavy, outer back plate construction and an inner copper or copper-like plate liner. The exposed inner surfaces of the liner form the inner casting face of the mold.
Examples of types of molds used in the continuous casting process are disclosed in prior patents of Floyd R.
Gladwin: U.S. Patent No. 3,964,727 issued June 22, 1976; U.S.
Patent No. 3,978,910 issued September 7, 1976; U.S. Patent No.
4,124,058 issued November 7, 1978; and U.S. Patent No. 4,129,175 issued December 12, 1978.
1217~4 1185.0~8 In the continuous casting operation, a metal strand is produced by pouring molten metal into the open upper end of the mold so that the metal in contact with the casting surfaces is cooled or chilled. This cooling forms a thin skin on the metal which skin surrounds an interior molten core. As the metal moves downwardly through the mold, due to the gravity, the thic~ness of the skin increases until the s~in is relatively rigid and self-sustaining. Further movement of the strand downwardly, out of the bottom of the mold, produces a substantially self~ustaining form, like a sla~ or billet, etc., comprising a thick skin surrounding a still-molten core. The strand is then cooled as it travels further from the mold until the strand is completely solidified. Once solidified, the strand is cut into useful lengths.
In this type of continuous casting mold, the molten metal and the mold walls are cooled by means of passing water through passageways formed within the mold liners and backing plates. The water cooling removes heat from the molten metal which is transmitted through the liners from their inner casting or molding surfaces.
It is important to cool the skin rapidly in order to thicken the skin so that the skin is reliably self-sustaining. Thus as the strand exits from the bottom of the mold, the skin will not rupture or burst or distort because of the pressure from the still molten core. However, as the metal cools in the mold, the skin tends to shrink away from the mold walls. While the skin is thin and pliable, the ferrostatic pressure of the molten core forces the skin outwardly into contact with the casting surfaces of the mold. But, as the skin thickens, the skin tends to stiffen and resist the ferrostatic pressure so that it shrinks inwardly, away from the casting surface, to provide a gap. Then the ferrostatic pressure forces the skin outwardly again and the cycle repeats. This results in a roughened, corrugated or wavy surface on the metal strand and uneven wear on the mold liner casting faces.
121~31D~
1185.008 The gap, which is referred to as an air gap, is not necessarily uniform around the periphery of the strand. For example, sometimes the gap may appear more at the corner areas of the mold than at the centers of the mold walls. Such air gap, in effect, acts like an insulation between the transfer of heat from the solidifying metal skin to the casting wall surface of the liner. This reduces the amount and rate of heat which is transferred from the metal outwardly through the mold and away through the cooling fluid.
Thus, it is desirable in the casting process to ~ceep the slcin in direct contact with the casting or inner face of the mold liner, throughout the entire height of the mold and to prevent the air gap effect which may occur due to shrinkage of the skin. One prior art technique for reducing these air gaps isdescribed in my prior application. A second technique for reducing air gaps is to taper the mold walls inwardly as described in some of the prior art cited by theExaminer in the aforementioned prior application. However7 none of these techniques have been successful.
The invention herein contemplates cooling the mold liner in a manner which reduces air gaps and permits the ferrostatic pressure of the moltencore to hold the newly forming skin outwardly against the casting walls throughout the entire length of the mold.
SUMMARY OF THE INVENTION
The invention herein contemplates substantially reducing the air gaps between the mold walls and the metal strand. Specifically a thin facing is applied to the interior of the mold walls and the facing is of gradually increasing thickness from its top toward its bottom. The facing is of a material such as nickel which has a substantially lower thermal conductivity than the mold wall.
While the use of a nickel facing is old, as illustrated for example in the Von Jan ~217~1~
11B5.005 et al U.S. Patent 4,197,902 of April 15, 1980, cited by the Examiner in my prior application, the prior art does not disclose the wlique idea where a facing may be of increasing thickness for gradually reducing the size of the mold cavity and gradually reducing the rate of cooling of the molten strand, to thus provide thethree benefits of (a) reducing air gaps, (b) providing an improved ~uality metalstrand surface, and (c) providing a uniform temperature on the mdd cavity facing thus reducing excessive mold wall wear.
If the nickel facing was of uniform thickness, as in the prior art, the rate of cooling therethrough would ~e constant but the metal strand would shrink away causing both air gaps and non-uniform temperature (and hence non-uniform wear) on the mold cavity walls.
If the nickel facing was of uniform thickness, as in the prior art, but positioned at an angle inwardly and downwardly, although the rate of coolingwould be constant, the mold cavity surface temperature would vary considerably.
Therefore, too rapid cooling of the strand and thickening of the skin tend to talce place in the middle of the mold, resulting in shrinkage, air gaps, and uneven mold wear.
The invention herein further comtemplates varying the thickness of the mold cavity by downwardly and inwardly tapering only the facing but not the inner plate or the outer backing plate. Thus facings according to the present invention may be retrofit onto existing mold plates.
By varying the facing thickness and angle as descri~ed above, the skin formed on the solidifying strand within the mold tends to remain in direct contact with the facing for a longer period of time. Air gaps are substantially reduced, resulting in direct transfer of heat from the skin to the facing without an intervening air insulation. Moreover, the rate or speed of removal of the strand from the mold can be somewhat increased, thus increasing overall casting efficiency.
12~7 1~
1185.008 DESCRIPTION OF THE DRAWINGS
These and other objects and advantages of this invention will become apparent upon reading the following description t~ken in conjunction with the drawings. In the drawings, wherein like reference numerals identify corresponding components:
Figure 1 is a perspective view, schematically showing a continuous casting mold, according to the present invention;
Figure 2 is a perspective view of the liner plate illustrating the cooling channels or grooves in the outer face thereof;
Figure 3 is a perspective view of the backing plate illustrating the innner face thereof;
Figure 4 is an enlarged cross-sectional view through the mold wall taken in the direction of arrows 4 4 of Figure l;
Figure 5 is a schematic fragmentary, cross-sectional view, drawn to an enlarged scale, illustrating the problem of air gaps according to the use of the prior art; and Figure 6 is a schematic, fragmentary, cross-sectional view, drawn to an enlarged scale, showing the relationship between the skin and the mold according to the principles of the present invention.
~Z1~3~4 1185.008 DETAILED DESCRIPTION OF THE INVENTION
Figure 1 schematically il~ustrates a continuous casting mold 10 ~ccording to the principles of the present invention. The mold is formed of a front wall 11, a rear wall 12, and a pair of opposed side walls 13 and 14. The walls are fastened together to ma~e up a rectangular shaped box-like configuration haYing an open top and an open bottom. The center portion of the box-like mold forms the casting cavity 15 into which the molten metal is poured for solidification.
The front and rear walls each include a face plate 17, which is often referred to as a sheath or liner plate, and which is usually made of copper or of a copper-like material for high heat conductivity. Each liner plate is fastened in face to face contact with an exterior, thicker, steel backing plate 18.
The steel bac~ing plate actually may be a fabricated construction comprising a relatively thick wall and an outer backing framework. However, for purposes of this diclosure, it is illustrated schematically as a relatively thick monolithic plate.
The spaced apart side walls 13 and 14 are located between the front and rear plates and are clamped in position with a suitable clamping or fastening mechanism which is not shown since it forms no part of the invention hereof. Each side wall includes a side wall interior face plate (or sheath or liner plate) 2~, which like the liner plates 17 used for the front and rear walls, are made of copper or a copper-like material. Likewise, each side wall liner plate is secured in face to face relationship to an exterior, thick, steel backing plate 21.
The liner plates 17, 20 may be bolted to their respective outer backing plates 18 or 21 with suita~le bolts or mechanical fasteners. Thus, each of the walls ~nsist of a pair of plates, i.e., the thinner copper liner and the outer, backing plate.
~2~73~
1185.008 ~ach of the liner plates 17 and 20 is provided with an outer (i.e., positioned away from the mold cavity 15) face 22 within which vertically arranged, groove-like channels 23 are formed. These channels carry & cooling fluid, such as water, which circulates through the channels for removing heat transmitted through the liner plates.
The inner (i.e., positioned toward the mold cavity 15) faces 24 of each of the backing plates 18 and 21, may ~e provided with horizontally arrangedupper and lower pockets or depressions 25 and 26 which act as headers for the passage of the cooling fluid. Conduits 27 are formed in the front and rear wall backing plates 18 and conduits 28 are formed in the backing plates 21 of the side walls. Typically, the water is circulated through the lower pockets 26, and thenthrough the channels 23, and out through the upper pockets 25.
Suitable pipes are provided to connect a source of cooling water to the conduits. However, these pipes are omitted as not ~eing part of the invention herein. Likewise, the liner plates must each ~e sealed to the backing plates to prevent water leakage between the plates. An example of a sealing system is described in the above mentioned l~.S. Patent No. 3,978,910 issued September 7,1976 to Floyd ~. Gladwin.
The inner or casting or molding surfaces of the liners 17, 20, i.e., the surfaces facing the mold cavity, are each coated with a wear resistant, thermally conductive facing or coating 29. An example of a suitable coating for this purpose is commercially available 201 type niclcel.
The invention herein contemplates first that the copper or copper-like plates 17, 20 are of uniform thickness along their vertical lengths and theinner cavity f~cing surfaces thereof are vertically oriented. By way of example,with a 3 foot high mold, each of the liners 17, 20 may be approximately one inchthick.
lZ~3~4 1185.008 The nickel facing or coating ag is tapered downwardly and inwardly of the mold cavity 15. For example, with the 3 foot high mold, the thickness of the nickel coating 29 would be about 0.125 inches at the top 33 thereof and about 0.250 inches at the bottom 34 thereof. Of course the nickel facing has a substantially lower thermal conductivity than the copper or copper-like facings.
The thinner upper edge 33 of each facing tends to transmit heat faster than the thicker lower edge portions 34 of each facing. Thus, heat transmission rate is gradually slower going from top to bottom of the facing. But the temperature of the cast metal is decreasing going from the top to the bottomof the cavity and thus less heat transmission is necessary as the strand progresses toward the bottom of the mold. Consequently, a more uniform temperature can be maintained at the mold-strand interface. Such temperature can be somewhat higher than that used in the past. Therefore, the skin formed remains pliable longer and because of the taper of the facing the skin is maintained in face to face contact with the facing by the ferrostatic pressure of the molten metal core. Thus there is a substantial reduction in air gaps.
By way of example, with the aforementioned wear material tapered facing formed of the 201 nickel, the mold cavity surface temperature can be maintained at roughly 1,500 degrees F. At this temperature, commonly used low melting point fluxes, lubricants and the like, will not deposit out upon the mold walls.
Figure 5 illustrates the prior art problem in the past where a mold wall lla, which is schematically shown as comprising an outer backing plate 18a,a uniform thickness inner liner 17a and a uniform thickness facing 29a receives the molten metal 35 ~gainst its surface. The skin 36a tends to gap away from the inner casting face of the facing 29a to produce an air gap 37, which functions lZ173~4 1185.008 as ~n insulator. ~uch an insulator actually reduces heat removal from the molten core and requires the strand to remain in the mold longer. The result is the same if the facing 29a is of uniform thickness and the inner face plate 17a is tapered inwardly and downwardly.
13y way of comparison, Figure 6 shows the improved construction herein where the facing 29 is tapered. Now, as the molten metal 35 is cooled, the skin 36 remains substantially in full contact with the casting suu face or inner wa~l surface of the facing throughout the height of the mold. The heat transfer from the molten core is at a greater rate at the top of the mold but the rate decreases along the length of the mold thus reducing the opportunity for strand shrinkage and reducing the likelihood of air gaps 37.
With this tapered facing construction, producing a more uniform temperature throughout the height of the mold, so-called "fire cracking" on the surface of the nickel facing is substantially reduced. That is, there is otherwise a tendency for cracks to form on the nickel facing at the upper part of the mold, where the free surface or meniscus of the poured molten metal is located.
Although the sizes of the molds may vary considerably, for example purposes, the mold wall could be of a height of about 30-36 inches9 withthe width of the front and rear walls being on the order of about 4 feet and thewidth of the end walls being on the order of about 9 inches, and face plates between about from 1 to 3 inches in thickness. Of course, the dimensions may change, depending upon requirements, with the dimensions set forth above being for illustrative purposes to show relative sizes of the parts.
lZ~73~L4 1185.008 With a mold of the general size and shape shown, a steel slab can be cast at a somewhat faster rate using the improved tapered facing, even though the transfer of heat from the s~in into the wall is somewhat slower overall. Because of $he greater uniformity of heat transfer, the skin tends to be thicker at the lower end of the mold than in the prior devices where air gaps appeared, so that the casting process can be speeded up while still obtaining either the same thicl~ness or a somewhat greater thiclcness skin where the sla~
emerges from the bottom of the mold.
The invention herein can be applied to existing continuous casting molds. That is, the copper liners can be removed and their outer faces can be covered with the nickel facing. This nickel facing may be secured or deposited in various ways as, for example, described in the aforementioned patent to Von Jan et al.
Having fully described an operative embodiment of this invention, I now claim:
Each of the walls is made of a relatively heavy, outer back plate construction and an inner copper or copper-like plate liner. The exposed inner surfaces of the liner form the inner casting face of the mold.
Examples of types of molds used in the continuous casting process are disclosed in prior patents of Floyd R.
Gladwin: U.S. Patent No. 3,964,727 issued June 22, 1976; U.S.
Patent No. 3,978,910 issued September 7, 1976; U.S. Patent No.
4,124,058 issued November 7, 1978; and U.S. Patent No. 4,129,175 issued December 12, 1978.
1217~4 1185.0~8 In the continuous casting operation, a metal strand is produced by pouring molten metal into the open upper end of the mold so that the metal in contact with the casting surfaces is cooled or chilled. This cooling forms a thin skin on the metal which skin surrounds an interior molten core. As the metal moves downwardly through the mold, due to the gravity, the thic~ness of the skin increases until the s~in is relatively rigid and self-sustaining. Further movement of the strand downwardly, out of the bottom of the mold, produces a substantially self~ustaining form, like a sla~ or billet, etc., comprising a thick skin surrounding a still-molten core. The strand is then cooled as it travels further from the mold until the strand is completely solidified. Once solidified, the strand is cut into useful lengths.
In this type of continuous casting mold, the molten metal and the mold walls are cooled by means of passing water through passageways formed within the mold liners and backing plates. The water cooling removes heat from the molten metal which is transmitted through the liners from their inner casting or molding surfaces.
It is important to cool the skin rapidly in order to thicken the skin so that the skin is reliably self-sustaining. Thus as the strand exits from the bottom of the mold, the skin will not rupture or burst or distort because of the pressure from the still molten core. However, as the metal cools in the mold, the skin tends to shrink away from the mold walls. While the skin is thin and pliable, the ferrostatic pressure of the molten core forces the skin outwardly into contact with the casting surfaces of the mold. But, as the skin thickens, the skin tends to stiffen and resist the ferrostatic pressure so that it shrinks inwardly, away from the casting surface, to provide a gap. Then the ferrostatic pressure forces the skin outwardly again and the cycle repeats. This results in a roughened, corrugated or wavy surface on the metal strand and uneven wear on the mold liner casting faces.
121~31D~
1185.008 The gap, which is referred to as an air gap, is not necessarily uniform around the periphery of the strand. For example, sometimes the gap may appear more at the corner areas of the mold than at the centers of the mold walls. Such air gap, in effect, acts like an insulation between the transfer of heat from the solidifying metal skin to the casting wall surface of the liner. This reduces the amount and rate of heat which is transferred from the metal outwardly through the mold and away through the cooling fluid.
Thus, it is desirable in the casting process to ~ceep the slcin in direct contact with the casting or inner face of the mold liner, throughout the entire height of the mold and to prevent the air gap effect which may occur due to shrinkage of the skin. One prior art technique for reducing these air gaps isdescribed in my prior application. A second technique for reducing air gaps is to taper the mold walls inwardly as described in some of the prior art cited by theExaminer in the aforementioned prior application. However7 none of these techniques have been successful.
The invention herein contemplates cooling the mold liner in a manner which reduces air gaps and permits the ferrostatic pressure of the moltencore to hold the newly forming skin outwardly against the casting walls throughout the entire length of the mold.
SUMMARY OF THE INVENTION
The invention herein contemplates substantially reducing the air gaps between the mold walls and the metal strand. Specifically a thin facing is applied to the interior of the mold walls and the facing is of gradually increasing thickness from its top toward its bottom. The facing is of a material such as nickel which has a substantially lower thermal conductivity than the mold wall.
While the use of a nickel facing is old, as illustrated for example in the Von Jan ~217~1~
11B5.005 et al U.S. Patent 4,197,902 of April 15, 1980, cited by the Examiner in my prior application, the prior art does not disclose the wlique idea where a facing may be of increasing thickness for gradually reducing the size of the mold cavity and gradually reducing the rate of cooling of the molten strand, to thus provide thethree benefits of (a) reducing air gaps, (b) providing an improved ~uality metalstrand surface, and (c) providing a uniform temperature on the mdd cavity facing thus reducing excessive mold wall wear.
If the nickel facing was of uniform thickness, as in the prior art, the rate of cooling therethrough would ~e constant but the metal strand would shrink away causing both air gaps and non-uniform temperature (and hence non-uniform wear) on the mold cavity walls.
If the nickel facing was of uniform thickness, as in the prior art, but positioned at an angle inwardly and downwardly, although the rate of coolingwould be constant, the mold cavity surface temperature would vary considerably.
Therefore, too rapid cooling of the strand and thickening of the skin tend to talce place in the middle of the mold, resulting in shrinkage, air gaps, and uneven mold wear.
The invention herein further comtemplates varying the thickness of the mold cavity by downwardly and inwardly tapering only the facing but not the inner plate or the outer backing plate. Thus facings according to the present invention may be retrofit onto existing mold plates.
By varying the facing thickness and angle as descri~ed above, the skin formed on the solidifying strand within the mold tends to remain in direct contact with the facing for a longer period of time. Air gaps are substantially reduced, resulting in direct transfer of heat from the skin to the facing without an intervening air insulation. Moreover, the rate or speed of removal of the strand from the mold can be somewhat increased, thus increasing overall casting efficiency.
12~7 1~
1185.008 DESCRIPTION OF THE DRAWINGS
These and other objects and advantages of this invention will become apparent upon reading the following description t~ken in conjunction with the drawings. In the drawings, wherein like reference numerals identify corresponding components:
Figure 1 is a perspective view, schematically showing a continuous casting mold, according to the present invention;
Figure 2 is a perspective view of the liner plate illustrating the cooling channels or grooves in the outer face thereof;
Figure 3 is a perspective view of the backing plate illustrating the innner face thereof;
Figure 4 is an enlarged cross-sectional view through the mold wall taken in the direction of arrows 4 4 of Figure l;
Figure 5 is a schematic fragmentary, cross-sectional view, drawn to an enlarged scale, illustrating the problem of air gaps according to the use of the prior art; and Figure 6 is a schematic, fragmentary, cross-sectional view, drawn to an enlarged scale, showing the relationship between the skin and the mold according to the principles of the present invention.
~Z1~3~4 1185.008 DETAILED DESCRIPTION OF THE INVENTION
Figure 1 schematically il~ustrates a continuous casting mold 10 ~ccording to the principles of the present invention. The mold is formed of a front wall 11, a rear wall 12, and a pair of opposed side walls 13 and 14. The walls are fastened together to ma~e up a rectangular shaped box-like configuration haYing an open top and an open bottom. The center portion of the box-like mold forms the casting cavity 15 into which the molten metal is poured for solidification.
The front and rear walls each include a face plate 17, which is often referred to as a sheath or liner plate, and which is usually made of copper or of a copper-like material for high heat conductivity. Each liner plate is fastened in face to face contact with an exterior, thicker, steel backing plate 18.
The steel bac~ing plate actually may be a fabricated construction comprising a relatively thick wall and an outer backing framework. However, for purposes of this diclosure, it is illustrated schematically as a relatively thick monolithic plate.
The spaced apart side walls 13 and 14 are located between the front and rear plates and are clamped in position with a suitable clamping or fastening mechanism which is not shown since it forms no part of the invention hereof. Each side wall includes a side wall interior face plate (or sheath or liner plate) 2~, which like the liner plates 17 used for the front and rear walls, are made of copper or a copper-like material. Likewise, each side wall liner plate is secured in face to face relationship to an exterior, thick, steel backing plate 21.
The liner plates 17, 20 may be bolted to their respective outer backing plates 18 or 21 with suita~le bolts or mechanical fasteners. Thus, each of the walls ~nsist of a pair of plates, i.e., the thinner copper liner and the outer, backing plate.
~2~73~
1185.008 ~ach of the liner plates 17 and 20 is provided with an outer (i.e., positioned away from the mold cavity 15) face 22 within which vertically arranged, groove-like channels 23 are formed. These channels carry & cooling fluid, such as water, which circulates through the channels for removing heat transmitted through the liner plates.
The inner (i.e., positioned toward the mold cavity 15) faces 24 of each of the backing plates 18 and 21, may ~e provided with horizontally arrangedupper and lower pockets or depressions 25 and 26 which act as headers for the passage of the cooling fluid. Conduits 27 are formed in the front and rear wall backing plates 18 and conduits 28 are formed in the backing plates 21 of the side walls. Typically, the water is circulated through the lower pockets 26, and thenthrough the channels 23, and out through the upper pockets 25.
Suitable pipes are provided to connect a source of cooling water to the conduits. However, these pipes are omitted as not ~eing part of the invention herein. Likewise, the liner plates must each ~e sealed to the backing plates to prevent water leakage between the plates. An example of a sealing system is described in the above mentioned l~.S. Patent No. 3,978,910 issued September 7,1976 to Floyd ~. Gladwin.
The inner or casting or molding surfaces of the liners 17, 20, i.e., the surfaces facing the mold cavity, are each coated with a wear resistant, thermally conductive facing or coating 29. An example of a suitable coating for this purpose is commercially available 201 type niclcel.
The invention herein contemplates first that the copper or copper-like plates 17, 20 are of uniform thickness along their vertical lengths and theinner cavity f~cing surfaces thereof are vertically oriented. By way of example,with a 3 foot high mold, each of the liners 17, 20 may be approximately one inchthick.
lZ~3~4 1185.008 The nickel facing or coating ag is tapered downwardly and inwardly of the mold cavity 15. For example, with the 3 foot high mold, the thickness of the nickel coating 29 would be about 0.125 inches at the top 33 thereof and about 0.250 inches at the bottom 34 thereof. Of course the nickel facing has a substantially lower thermal conductivity than the copper or copper-like facings.
The thinner upper edge 33 of each facing tends to transmit heat faster than the thicker lower edge portions 34 of each facing. Thus, heat transmission rate is gradually slower going from top to bottom of the facing. But the temperature of the cast metal is decreasing going from the top to the bottomof the cavity and thus less heat transmission is necessary as the strand progresses toward the bottom of the mold. Consequently, a more uniform temperature can be maintained at the mold-strand interface. Such temperature can be somewhat higher than that used in the past. Therefore, the skin formed remains pliable longer and because of the taper of the facing the skin is maintained in face to face contact with the facing by the ferrostatic pressure of the molten metal core. Thus there is a substantial reduction in air gaps.
By way of example, with the aforementioned wear material tapered facing formed of the 201 nickel, the mold cavity surface temperature can be maintained at roughly 1,500 degrees F. At this temperature, commonly used low melting point fluxes, lubricants and the like, will not deposit out upon the mold walls.
Figure 5 illustrates the prior art problem in the past where a mold wall lla, which is schematically shown as comprising an outer backing plate 18a,a uniform thickness inner liner 17a and a uniform thickness facing 29a receives the molten metal 35 ~gainst its surface. The skin 36a tends to gap away from the inner casting face of the facing 29a to produce an air gap 37, which functions lZ173~4 1185.008 as ~n insulator. ~uch an insulator actually reduces heat removal from the molten core and requires the strand to remain in the mold longer. The result is the same if the facing 29a is of uniform thickness and the inner face plate 17a is tapered inwardly and downwardly.
13y way of comparison, Figure 6 shows the improved construction herein where the facing 29 is tapered. Now, as the molten metal 35 is cooled, the skin 36 remains substantially in full contact with the casting suu face or inner wa~l surface of the facing throughout the height of the mold. The heat transfer from the molten core is at a greater rate at the top of the mold but the rate decreases along the length of the mold thus reducing the opportunity for strand shrinkage and reducing the likelihood of air gaps 37.
With this tapered facing construction, producing a more uniform temperature throughout the height of the mold, so-called "fire cracking" on the surface of the nickel facing is substantially reduced. That is, there is otherwise a tendency for cracks to form on the nickel facing at the upper part of the mold, where the free surface or meniscus of the poured molten metal is located.
Although the sizes of the molds may vary considerably, for example purposes, the mold wall could be of a height of about 30-36 inches9 withthe width of the front and rear walls being on the order of about 4 feet and thewidth of the end walls being on the order of about 9 inches, and face plates between about from 1 to 3 inches in thickness. Of course, the dimensions may change, depending upon requirements, with the dimensions set forth above being for illustrative purposes to show relative sizes of the parts.
lZ~73~L4 1185.008 With a mold of the general size and shape shown, a steel slab can be cast at a somewhat faster rate using the improved tapered facing, even though the transfer of heat from the s~in into the wall is somewhat slower overall. Because of $he greater uniformity of heat transfer, the skin tends to be thicker at the lower end of the mold than in the prior devices where air gaps appeared, so that the casting process can be speeded up while still obtaining either the same thicl~ness or a somewhat greater thiclcness skin where the sla~
emerges from the bottom of the mold.
The invention herein can be applied to existing continuous casting molds. That is, the copper liners can be removed and their outer faces can be covered with the nickel facing. This nickel facing may be secured or deposited in various ways as, for example, described in the aforementioned patent to Von Jan et al.
Having fully described an operative embodiment of this invention, I now claim:
Claims (7)
1. In a continuous molten metal casting mold formed of opposed, vertically arranged, spaced apart walls defining an open top and bottom box-like configuration, into the top of which molten metal is poured for forming, against the interior faces of the walls a solidified metal skin which surrounds a molten metal core to provide a partially solidified metal stand which is continuously removed downwardly out of the bottom of the mold, with each of said mold walls being formed of a relatively thick, metal outer backing plate and a relatively thin, copper-like liner plate, with the two plates fastened together in face to face relationship, and with each mold wall having internal fluid cooling passageways formed therein for continuously cooling the walls the improvement comprising:
an inner facing on said liner plate, said facing having an exposed interior face forming the casting surface of the mold against which the molten metal skin is formed by solidification;
said inner facing having a substantially lower thermal conductivity than said liner plate;
the interior face of at least one of the inner facings, that is, the face arranged toward the interior of the mold, being tapered downwardly and inwardly from top to bottom of the mold so that said facing gradually increases in cross-sectional wall thickness from its top toward its bottom.
an inner facing on said liner plate, said facing having an exposed interior face forming the casting surface of the mold against which the molten metal skin is formed by solidification;
said inner facing having a substantially lower thermal conductivity than said liner plate;
the interior face of at least one of the inner facings, that is, the face arranged toward the interior of the mold, being tapered downwardly and inwardly from top to bottom of the mold so that said facing gradually increases in cross-sectional wall thickness from its top toward its bottom.
2. A mold as defined in claim 1, and including said backing plate and said liner plate each being of substantially constant thickness in cross-section, from top to bottom.
3. A mold as defined in claim 1, wherein all of the liners of all of the walls of the mold are formed with said facings for gradually increasing the mold liner cross-sectional thicknesses from top to bottom of the mold.
4. A mold as defined in claim 1, and including vertically elongated, narrow, fluid carrying channel-like grooves formed in liner plate and cooling fluid passageways formed in the backing plate to convey cooling fluid through the grooves;
and with the bases of said grooves being arranged roughly parallel to the plane of the liner plate so that the thickness of facing material between said bases of said grooves and the exposed interior casting face of the facing gradually increases from the top to the bottom of the liner.
and with the bases of said grooves being arranged roughly parallel to the plane of the liner plate so that the thickness of facing material between said bases of said grooves and the exposed interior casting face of the facing gradually increases from the top to the bottom of the liner.
5. A mold as defined in claim 1, wherein said facing is nickel.
6. In a continuous molten metal casting process, a method for reducing air gaps between the solidifying skin of a continuously cast strand and the inner casting face of the mold, in which process the mold is formed of spaced apart walls defining an open top and bottom box-like configuration, into the top of which molten metal is poured for solidification of a skin against the mold wall inner casting face, with the partially solidified strand removed downwardly from the open bottom of the mold, and with the mold walls each formed of an outer backing wall plate and an intermediate copper-like liner plate, with the two plates being arranged in general face to face contact, and with fluid cooling passageways formed within each of the walls for removing heat from the casting face, the improvement comprising:
providing an inner facing on said liner plate;
said inner facing being of substantially lower thermal conductivity then said liner plate; and reducing the rate of cooling of said cast strand from the top of the mold to the bottom of the mold.
providing an inner facing on said liner plate;
said inner facing being of substantially lower thermal conductivity then said liner plate; and reducing the rate of cooling of said cast strand from the top of the mold to the bottom of the mold.
7. A continuous molten metal casting process as defined in claim 6, and including the step of increasing the cross-sectional thickness of the facings by tapering their wall surfaces, that is, the surfaces in contact with the strand, inwardly and downwardly from top to bottom of the mold for reducing said rate of cooling.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US51901583A | 1983-08-01 | 1983-08-01 | |
| US519,015 | 1983-08-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1217314A true CA1217314A (en) | 1987-02-03 |
Family
ID=24066420
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000442040A Expired CA1217314A (en) | 1983-08-01 | 1983-11-28 | Tapered mold liner facing |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1217314A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2318314A (en) * | 1996-10-15 | 1998-04-22 | Davy Distington Ltd | Continuous casting mould with a coating of varying thickness |
-
1983
- 1983-11-28 CA CA000442040A patent/CA1217314A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2318314A (en) * | 1996-10-15 | 1998-04-22 | Davy Distington Ltd | Continuous casting mould with a coating of varying thickness |
| US6176298B1 (en) | 1996-10-15 | 2001-01-23 | Davy Distington Limited | Continuous casting mould |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0583867B1 (en) | Method and apparatus for continuous casting of metals | |
| US5176197A (en) | Continuous caster mold and continuous casting process | |
| US2956320A (en) | Casting of metal | |
| TWI268821B (en) | Adjustment of heat transfer in continuous casting molds in particular in the region of the meniscus | |
| CA2247785A1 (en) | Molds for a continuous casting system | |
| US6315030B1 (en) | High speed continuous casting device and relative method | |
| CA1217314A (en) | Tapered mold liner facing | |
| US4252178A (en) | Continuous casting mold with resiliently held graphite liner members | |
| US3339623A (en) | Thermal bending of continuous castings | |
| EP0448773B1 (en) | Continuous caster mold and continuous casting process | |
| KR20010089433A (en) | Mould plate of a continous casting plant | |
| JP2950152B2 (en) | Continuous casting mold for slab | |
| JPS62130763A (en) | Metallic mold | |
| US5299627A (en) | Continuous casting method | |
| CA1228969A (en) | Method of and apparatus for continuously casting metal in a shaping cavity having cooled rotating walls | |
| US6176298B1 (en) | Continuous casting mould | |
| US5095970A (en) | Continuous-casting mold for vertically casting metal strip | |
| US4744406A (en) | Horizontal continuous casting apparatus with break ring formed integral with mold | |
| CZ289354B6 (en) | Mould pipe for a continuous casting mould for the continuous casting of steels, especially peritectic steels | |
| AU692236B2 (en) | Method and apparatus for twin belt casting | |
| JPH0270358A (en) | Mold for continuous casting | |
| HU208268B (en) | Apparatus for continuous casting thin metal products | |
| JP2808633B2 (en) | Continuous casting mold and control method thereof | |
| CA1240819A (en) | Apparatus for closing off the sides of a shaping cavity of substantially rectangular cross-section in a continuous casting installation | |
| CA1234675A (en) | Mold wear compensator |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |