JPH05200499A - Method of metal casting - Google Patents

Abstract

PURPOSE: To prevent the generation of inclusions, such as oxides, and the generation of pleats and wrinkles on an outside surface by receiving the pouring of molten metal in a flat portion and maintaining the molten metal as a liquid until vortexes disappear, then cooling the molten metal, thereby forming a solidified strip. CONSTITUTION: The molten metal 10 from a tundish 40 is poured to a moving substrate 20 lined with foil material 32. The moving substrate 20 is formed of a refractory block 22 and the length on a lining side 38 has a sufficient length, is so set that the molten metal 10 exists in the state of the liquid within the lining side 38 until the molten metal turns to the liquid static in a trough portion and attains a static state with respect to the foil material 32. The cooling is not executed during this process. The liquid is then moved into a support surface 50 and the cooling liquid is sprayed to the bottom of the foil material 32 through the net body of the support surface 50 by a cooling spray 60. The casting is detached from the support surface 50 after complete solidification and is sent to the ensuing stage. Porous cavities are not formed in the casting and the generation of the inclusions, such as the oxides, and the generation of the pleats and wrinkles on the outside surface of the strip may be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a metal casting method, and more specifically to an improved continuous casting method for a metal strip or a thin metal sheet and an apparatus therefor.

[0002]

BACKGROUND OF THE INVENTION The metalworking industry has developed methods and apparatus for producing as-cast products that require little or no additional treatment such as hot rolling to reduce the thickness of the strip. .. One of the methods resulting from this development is the single belt casting method. In this method, molten metal is caused to flow over a moving horizontal surface in the form of a continuous belt. The molten metal solidifies while moving with the belt. This elongated solid metal strip is removed from the continuous belt and sent for any subsequent processing.

Attempts have been made to increase the casting speed (inches / minute) of cast strips and to reduce the thickness of the cast alloy in order to eliminate the subsequent processing work. Several problems have arisen in relation to. This is because the relative flow between the molten metal and the belt causes splashes and vortices.

Usually, the molten metal source is arranged at a certain distance in the vertical direction from the belt. If the molten metal is allowed to flow directly over the belt from the molten metal source over the entire vertical distance, splashes will hit the belt and form a porous cavity inside the casting. .. Alternatively, a vortex is generated to generate inclusions such as oxides, or creases or wrinkles are formed on the outer surface of the solidified strip.

A typical attempt made to solve these problems has been an attempt to improve the feeding means by providing a tundish between the molten metal source and the belt. Such a supply means normally receives a metal stream emanating from a source of molten metal and pours it in the direction of belt movement. Although this method can solve the problem of splashes, it does not solve the problem of decelerating the metal flow and eliminating the vortex flow.

Another disadvantage of the belt casting method is the slow cooling rate of the molten metal on the belt. As the metal solidifies on the belt, an air gap is created between the belt and the strip. The low heat transfer rates in these air gaps result in non-uniform heat transfer from the metal. As a result, cracks and porous cavities are formed in the metal, which lowers product quality.

The following references describe studies of various pouring systems used for pouring molten metal into belt casters. J. Herbertson, P. C. Campbell, A. G. Hunt, J. Freeman (J. Herbertson, PC Cambe
ll, A. G. Hunt, J .; Freeman) "B
Strip casting research at HP Central Research Institute "(" Stripe
Casting Studies at BHP C
Entral Research Lobrator
ies ”(CCC '90 5th International Foundry Conference, 199
Linz, June 0). J. Herbertson & R.
I. L. Guthrie (J. Herbertson & R.
I. L. Guthrie) "New Invention of Metal Discharge on Thin Strip Casters" (Casting of Near)
Net Shaped Products, TMS-A
IME, 335-349). J. S. Trulove,
T. A. Gray, P.G. C. Campbell, J. Herbertson (JS Trulove, TA Gray,
P. C. Campbell, J.M. Herbertso
n) "Fluid mechanics in high speed strip casting metal discharge system" (International Conferen)
ce on New Smelting Reduct
ion of Near Net Shaped Casting Technologies of S
steel, SRNC-9, J. S. Truelove,
1/10 to 11/10).

Many attempts at developing transfer systems have been directed to producing high quality strips by reducing or minimizing eddy currents of liquid phase metals and increasing cooling rates. , Results in this direction are not entirely satisfactory.

[0009]

SUMMARY OF THE INVENTION It is thus an object of the present invention to provide an improved casting system which minimizes vortexing of liquid phase metals. Yet another object of the invention is to improve the casting system so that the cooling rate of castings cast from molten metal to strips is improved.

[0010]

According to the present invention, eddies are minimized by allowing the molten metal to be cast itself to slow down and delaying solidification until it is slowed down to the desired degree. This task was achieved according to the invention by the following method. That is, the movable base was made to pass under the molten metal source, and the flat portion of the base was made to receive the molten metal at the molten metal pouring point during the passage. The molten metal is retained as a liquid on a movable substrate until the vortex slows down itself, after which it is cooled and solidified.

The cooling rate aimed at by the present invention is achieved by the following method. That is, a molten metal source is provided so that the movable base body passes under the molten metal source, and at the time of passage, the molten metal is poured into the flat portion of the base body at the pouring point,
A strip is formed on the base. The strip is transferred from the movable belt onto an open support mesh and supported on this support until it is completely solidified, before it is completely solidified over its entire thickness.

The apparatus for carrying out the method of the present invention comprises a source of molten metal, a movable base having a flat portion which passes through the molten metal casting point and on which a strip is formed, and on the movable base completely. An open support mesh through which the strip passes before it solidifies.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood by reference to the following description and the accompanying drawings. The present invention relates to the casting of strips or sheets of molten metal. Strip or sheet means a metal with a rectangular cross section whose width value is greater than its thickness value, in which case
The thickness is about 3.175 to 19.05 mm (about 1/8 to 3 /
4 inches), preferably about 6.35 to 12.7 m
m (about 1/4 to 1/2 inch). The present invention is applicable to many metals, but is particularly applicable to copper or copper alloys.

In the drawings, and in particular in FIG. 1, a casting system to which the invention is applied is schematically illustrated. Molten metal 10 is supplied to a casting apparatus 12 from a container 14 having a tap hole 16 lined with a refractory material. Inside the container 14, the plunger 1
8 is provided and cooperates with the tap 16 to control the flow of molten metal from the vessel 14. For this purpose, the plunger 18 is adapted to reciprocate vertically by any suitable mechanism (not shown).

A continuously moving substrate device 20 is a container 1
It is arranged under the tap hole 16 of No. 4. This device 20
Has a continuous belt extending between horizontally spaced rollers 24, or an endless track consisting of a plurality of segments or blocks 22 joined together. Laura 2
One of the four is connected to a suitable drive (not shown) to drive the belt of segments at a suitable speed and in the direction of the arrow. These segments or refractory blocks 22 are made of a suitable refractory material. The refractory serves as a heat insulating material that prevents heat transfer from the molten metal casting to the refractory.

As shown in FIG. 2, the refractory block 22 is
A trough portion 26 formed inside thereof and extending inward from the outer surface
Have. The gutter portion 26 comprises a flat bottom surface 28 and opposed side walls 30. The trough portion 26 also forms a continuous trough in the base device 20 and extends in the direction of movement of the base device.

A preformed foil material 32 having a bottom surface 34 and sidewalls 36 is fed to the upper side 38 of the base device 20 and adapted to move with the refractory block 22. The foil material 32 has a shape that fits within the gutter portion 26 within the refractory block 22. The foil material 32 is also made of low carbon steel, but any steel alloy from low carbon steel to stainless steel can be used. Furthermore, the foil material must have a sufficient thickness so that the molten metal does not melt the foil material through its entire thickness before it is cooled. The thickness of the foil material is preferably less than or equal to 0.254 mm (0.01 inch), but usually 0.051 to
It may be 0.254 mm (0.002-0.01 inch). The foil material is shaped so as to have a gutter-shaped cross section by suitable means (not shown) such as shaping rods or rollers. The foil material 32 is also fed from a suitable supply to the upper side 38 of the substrate device and moves therewith.

Tundish 40 lined with refractory
A supply means such as is provided between the container 14 and the continuous substrate device 20 at a position where the molten metal flow poured out from the tap hole 16 of the container 14 comes into contact. Tundish 40
Has a refractory lined gutter which has a generally flat beveled bottom surface 44 with vertically extending side edges 46. Tundish 40
Is inclined as seen in FIG. 1 so that its flat bottom surface 44 is inclined downward toward the downstream end of the upper side 38 of the continuous substrate device 20.

The support surface 50 is provided downstream of the tight side 38 of the movable base device 20. The support surface 50 is made of a filter material such as a coarse mesh, which allows air and water to pass therethrough. This support surface 50 has the form of a continuous belt 52 wrapped around rollers 54 and has a flat tension side 56 which is flush with the bottom surface of the gutter 26. The continuous belt 52 moves in the direction indicated by the arrow in FIG. Alternatively, the support surface 50 may be in the form of a table and a pinch roller may be provided downstream of the table to grip the foil material and cast strip and pull on the table. The net body is made of steel, but may be made of other materials such as copper, copper alloy, and aluminum.

A cooling spray 60 is provided below the tight side 56 of the connecting belt 52 to cool the bottom surface of the foil material and its upper strip.

A static support surface 62 is provided in the same plane as the bottom surface of the trough side 38 of the base device 20 and the tension side 56 of the continuous belt 52 to fill the gap between the bottom surface of the trough portion and the tension side 56. Be done.

At the time of work, the molten metal is used in the tundish 40.
Is poured into the trough portion 26 lined with a preformed foil material 32. The length of the tension side 38 of the movable substrate 20 is set to have a sufficient length so that the vortex flow is naturally decelerated, and the molten metal becomes a stationary liquid in the trough portion, and becomes stationary with respect to the foil material. , Liquid side up 3
Be within 8. Fireproof block 2 during this process
2 or cooling of the molten metal is not performed. The preformed foil material 32 is induction preheated to minimize distortion during contact with the molten metal. The contact length on the tension side of the movable substrate device depends on the alloy to be cast, but in the case of a copper alloy, it is about 152.4 to 254 mm (about 6 to 10 inches).
And preferably about 20 inches (8 inches).

After the molten metal has settled, the metal and foil material are transferred onto a support surface 50 where they are cooled by a cooling spray 60. The cooling spray 60 sprays water or other cooling fluid upward through the mesh of the support surface 50 onto the bottom of the foil material. After being completely solidified, the cast metal and foil material is released from the support surface 50 and sent to the next desired step.

If the foil material is deposited on the cast metal strip, it is removed by conventional cutting. The foil material can also be coated with a suitable material such as boron nitride or graphite, after which molten metal is poured and the foil material can be separated and reused after the strip has solidified.

With the above-described structure, the molten metal vortex of the horizontal movable belt keeps the metal as a liquid on the movable belt until the vortex disappears, and when the vortex disappears, the cast metal is cooled and solidified. A board is obtained.

Referring now to the drawings, and in particular to FIGS. 3 and 4, one embodiment of the casting system used to carry out the method of the present invention will be described in detail. The casting system has a movable substrate 110 in the form of a casting drum or wheel 112 having a cylindrical outer surface 114. This outer surface 114
A groove 116 is formed in the circumferential direction. This groove 116
Are formed by the bottom surface and the side walls facing each other. The casting drum or wheel is centered on its axis
It can be rotated in the direction of the arrow in FIG. This rotation is performed by an appropriate mechanism (not shown) such as a motor.

The tundish 122, mounted in the immediate vicinity of the casting drum or wheel 112, has a supply of molten metal 124. Tundish 122
Has a tap hole or nozzle 126 at which a molten metal meniscus 128 is formed. This meniscus maintains contact with the outer surface of the casting drum or wheel 112. The tundish 122 is supported in a fixed positional relationship with the casting drum or wheel 112 by a suitable frame structure (not shown).

As the casting drum or wheel 112 rotates, its outer surface 114 passes through the tundish tap or nozzle 126 and contacts the molten metal meniscus 128. Molten metal 124 substantially wets the outer surface of the drum or wheel 112 and is dragged onto the outer surface and deposits in the groove 116. This metal moves with the drum or wheel 112 until it disengages from the drum or wheel 112 at the vertical apex as strip 130.

The tundish 122 is made of a rigid high strength material, such as a cast ceramic material, or a rigid metal frame structure lined with a suitable refractory material. By doing this, tundish 12
The heat loss of the molten metal 124 contained in 2 is minimized.

The wheel or drum 112 is made of any suitable material, for example, a metal that does not melt or break under working conditions. These suitable metals include steel, copper and copper alloys. Other materials that can be used are, for example, graphite and ceramic materials such as boron nitride.

Supporting surface 13 with mesh for strip 130
2 is located downstream of the drum or wheel 112 as shown. The support surface 132 is made of a filter-like material that is permeable to air and water, for example, an open mesh. Ideally, this support surface 132 is a movable continuous belt 13 wrapped around spaced rollers 136.
It has four formats. The belt 134 moves in the direction of the arrow in FIG. 3 and has a tension side 138. But also
The support surface 132 may have the form of a stationary table such that the driven pinch rollers located downstream of the upper surface 150 move the strip across the table. The open mesh is made of steel, preferably stainless steel.

The tension side 138 is the drum or wheel 1
It is located in a plane tangential to the 12 vertical vertices. Stationary support 140 coplanar with the upper surface of tension side 138
Are located between the wheel or drum 112 and the upstream end of the tension side 138 to fill the gap between them.
A cooling spray 142 is arranged below the upholstered side 138, and a cooling fluid such as water is sprayed to the bottom surface of the strip 130 through the mesh.

The work is performed on the tap 1 of the tundish 122.
The molten metal flowing out of 26 forms a meniscus 128 for the rotating drum or wheel 112. Molten metal from meniscus 128 is dragged into the rotating drum and enters groove 116. Strip plate 13 at the vertical vertex
The length of movement of the molten metal on the drum until the zero leaves the drum is set such that the casting strip 130 can be transferred to the bearing surface 132 before it completely solidifies over its entire cross section. It Ideally, the strip 130 is an open netting as soon as the solidified shell is formed on the bottom and sides of the strip 130 and becomes sufficiently thick that there is no risk of fracture due to the weight of the remaining molten metal. 132 so that it can be moved to above.

FIG. 4 is a diagram of the second embodiment and shows a casting system to which the present invention is applied. Molten metal 150 is tap 1
A refractory lined vessel 154, having 56, is fed to the casting apparatus 152. A plunger 158 is provided inside the container 154, and the plunger 158 cooperates with the tap hole 156 to control the molten metal flow exiting the container 154. For this control purpose, the plunger 158
It reciprocates in the vertical direction by an appropriate mechanism (not shown).

A continuous belt device 160 having a flat, horizontal tensioning side 162 is located below the tap 156 of the container 154. The belt device 160 includes a flexible belt 164 that is wound around rollers 166 that are arranged at intervals in the horizontal direction and that extends between the rollers 166. One of the rollers 166 is coupled to a suitable drive means (not shown) to drive the belt 164 at the proper speed in the direction of the arrow.
To drive.

The belt 164 is made of a solid material such as steel,
It is preferably made of low carbon steel, but other materials can be used as long as they do not melt upon contact with the molten metal to be cast.

Between the container 154 and the continuous belt device 160, the molten metal stream 1 discharged from the tap hole 156 of the container 154.
A supply means, for example, a tundish 170 lined with a refractory material is arranged at a position where 66 contacts.
The tundish 170 has a gutter-shaped member lined with a refractory material. The trough has a generally flat beveled bottom surface 172 that extends vertically and has spaced side edges. The tundish 170 has a flat bottom surface 172 that slopes downwardly toward the downstream end of the tension side 162 of the continuous belt 164, as seen in FIG.
The spaced side edges 176 allow movement with the belt, or are stationary structures along each edge of the tensioning side 162 of the belt 164 and are transverse to the direction of movement of the belt 164 of molten metal. Is restricted.

A support surface 180 is provided downstream of the tension side 162 of the movable belt 160. This support surface 180
Is similar to the support surface 132 of the previous embodiment shown in FIG. 3 and is made of a filter-like material such as a mesh that is permeable to water or air. The support surface 180 also takes the form of a continuous belt 182 wrapped around spaced rollers 184 and has a tensioning side 186 that moves in the direction of the arrow in FIG. As in the previous embodiment, the support surface 180
Is configured in the form of a stationary table and the strip is
It is also possible to move it on the table by a driven pinch roller arranged downstream of 0. The open mesh is made of steel, preferably stainless steel.

The tension side 186 of the belt 182 is the belt 1
It is located on the same plane as the tension side 162 of 64. Between the downstream end of the tension side 162 of the belt 164 and the upstream end of the tension side 186 of the belt 182, both tension sides 16
Stationary support surface 1 which is flush with the upper surface of 2,186
88 is provided to fill the gap between both tension sides 162, 186.

Cooling sprays 190 to 192 are arranged below the tension side 162 of the belt 164 and below the tension side 186 of the belt 182, respectively, to cool the bottom surface of the strip.

During operation of this embodiment, molten metal 166
Tundish 170 to belt 164 tension side 162
It is leaked to the top. The length (contact length) of the tension side 162 with which the metal comes into contact is such that the strip 100 is supported by the support surface 18 of the mesh body before the entire cross section of the cast metal strip 100 is completely solidified.
Set the length so that it moves to 0. On the bottom of the strip 100,
As soon as a solidified shell having a thickness sufficient to prevent breakage due to the weight of the remaining molten metal is formed, the supporting surface 18 of the mesh body is immediately
Ideally, the strip 100 is moved to zero. The contact length on the belt tension side will depend on the degree of effective cooling obtained and the alloy being cast. When the bottom surface is cooled with a copper alloy, the tension side is about 101.6 to 203.2 m.
m (about 4 to 8 inches), preferably about 15
It is 2.4 mm (about 6 inches).

With the above arrangement, the cooling rate of the casting is improved by eliminating the air gap that normally occurs between the solid substrate and the strip.

Although the present invention has been described with reference to a plurality of specific embodiments, it goes without saying that many changes, modifications and variations can be made without departing from the scope of the present invention. Therefore, all such changes, modifications, and variations included in the concept of the claims are included in the present invention.

[Brief description of drawings]

FIG. 1 is a schematic elevational view showing a partial cross-section of a casting apparatus to which the present invention is applied.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a schematic elevational view showing a first embodiment of a casting apparatus to which the present invention is applied in a partially sectional view.

FIG. 4 is a schematic elevational view showing a second embodiment of a casting apparatus to which the present invention is applied partially in section.

[Explanation of symbols]

 10 molten metal 14 container 16 tap hole 18 plunger 20 base device 22 fireproof block 24 roller 26 gutter portion 28 bottom surface 30 side wall 32 foil material 34 bottom surface 38 tension side 40 tundish 42 molten metal flow 50 support surface 60 cooling spray

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Harvey P. Ceskys 4 Country Road, North Haven, Connecticut, United States

Claims (11)

[Claims] 1. A method for casting a metal (10) into a thin plate (36) or strip, comprising: (a) providing a molten metal source (14, 16); (b) a moving substrate (20) being a molten metal source. Under the flat part of the substrate (2
6) to receive molten metal at the molten metal pouring point, (c) supply the molten metal onto the substrate, (d) maintain the molten metal as a liquid until the vortex disappears, then A method of casting a metal, which comprises cooling the metal to form a solidified strip. 2. Method according to claim 1, characterized in that the movable substrate (20) comprises a refractory material. 3. A molten metal source (1) on the substrate (20).
Method according to claim 2, characterized in that a foil material (32) is provided between the substrate (16, 16) and the substrate receiving the molten metal. 4. The substrate has a gutter (34, 36) therein, the foil material is provided on the gutter and moves with the substrate to coat the inside of the gutter, The foil material and the molten metal remain on the substrate until the molten metal rests against the foil material, after which the foil material and the molten metal from the substrate (20) onto a support surface. 4. The method of claim 3, wherein the molten metal is moved to and cooled. 5. A cooling spray () in which the support surface (50) is a mesh and the apparatus for effecting the cooling of the molten metal is directed through the mesh and towards the bottom of the foil material. 60) Method according to claim 4, characterized in that 6. A method of casting metal comprising: (a) providing a source of molten metal (14), and (b) passing a movable substrate (110) through a position associated with the source of molten metal to produce the molten metal. Receiving and forming this molten metal into a strip on the substrate (110), (c) the strip (130) to the movable substrate (110).
From above, before the band is completely solidified over its entire thickness, it is transferred onto an open support net (132), and the open support net supports the strip until completely solidified. .. 7. Method according to claim 6, characterized in that the underside of the strip facing the support net is cooled by a cooling spray (142). 8. The point at which the strip (130) is delivered from the movable substrate immediately after the solidified shell below the strip is formed to a thickness sufficient not to break due to the weight of the remaining molten metal. 7. The method of claim 6, wherein: 9. The movable base is a rotating wheel (110).
7. The method of claim 6, wherein: 10. The endless belt (160) wherein the movable substrate is an endless belt.
7. The method of claim 6, wherein: 11. The open support net is a continuous belt (13).
2, 180).