JP2548696B2 - Direct casting and equipment of molten metal into continuous strips of crystalline metal - Google Patents

Description

Description: FIELD OF THE INVENTION This invention relates to a method and apparatus for casting metal alloys directly from molten metal into continuous strips. More particularly, the invention relates to feeding molten metal through an open outlet of a casting vessel onto a moving casting surface to solidify into a continuous strip of the desired thickness.

In conventional manufacture of metal strips, such methods include casting the melt in ingot or billet or slab form, typically with various steps in the process to provide the desired strip thickness and quality. Each of the steps includes one or more hot and cold rolling steps, as well as pickling and annealing steps. Especially 0.010 inch to 0.100 inch (0.0254 cm to
The production cost of continuous strips with as-cast dimensions in the range of 0.254 cm) can be reduced by omitting some of the processing steps of conventional methods. The as-cast strip is conventionally processed by cold rolling, pickling and annealing.
002 inches to 0.040 inches (0.00508 cm to 0.1016 cm)
Can be the final dimensions of

Various methods and devices for producing direct cast strips are known. To give a representative example of such a method,
To spray the melt through a metering orifice and across a gap onto a rapidly moving quench surface, such as a wheel or continuous belt: To partially submerge the rotating quench surface in the melt pool: Use a horizontal link belt as a quench substrate Then
A method of pouring a molten metal on this substrate to solidify it: and a method of casting with a twin casting roll having a molten metal pool therebetween.

For mass production of strips of good quality and texture,
Direct casting of molten metal through an orifice has long been attempted. U.S. Patent No. 112,05 dated February 21, 1871
No. 4 discloses a method for producing a flat solder wire from a molten metal that is pumped through an orifice onto a rotary casting surface. Similarly, US Pat. No. 905,758 issued Dec. 1, 1908.
U.S.A. British Patent No. 24,3 dated October 24, 1910
No. 20 discloses a method of making a sheet or strip from a melt flowing through a tube channel having at least one side in contact with a moving casting surface. A more recent example of a device is King's U.S. Pat. No. 3,522,836, issued Aug. 4, 1970, which leaves a convex meniscus protruding from the nozzle and places the surface in front of the nozzle orifice outlet. Move it and pull out the material continuously,
A method of solidifying as a continuous product is disclosed. The molten material is maintained at static equilibrium at the outlet and gravity in continuous contact with the moving surface. U.S. Pat. No. 4,221,257 issued September 9, 1980 to Narasimhan relates to a method of pumping molten metal under pressure through a slotted nozzle onto the surface of a moving chill body.

Orifice casters are generally limited to thin as-cast material, typically on the order of less than about 0.010 inch (0.0254 cm) thick. Such castings are likely to be of limited size, as moving quench surfaces are likely to be limited to those that can solidify and transfer as the melt is delivered from the nozzle orifice. Such a device functions as a melt pump, transferring excess melt from the orifice to the quench surface in a molten state with more heat than can be extracted to form the appropriate strip. By reducing the melt delivery rate and / or increasing the rate of the quench surface, such a situation can be overcome, but with a resulting reduction in thickness.

When trying to produce crystalline strips at high speeds in conjunction with orifice type casting equipment, the quality is usually poor.
When the molten metal is sprayed on a high-speed cooling surface or flowed over a horizontal belt moving at a low speed over the entire width,
The molten metal leaves the supply supply rapidly in a partially molten state. This is the case when the quality deteriorates. Because the strip rapidly solidifies from its surface
This is because contraction occurs. This shrinkage can only be moderated by a fresh supply of melt. Without such a new supply of molten metal, cracks would rapidly form in the structure of the strip, considerably impairing its physical properties. US Patent No. 4,274,473 issued June 23, 1981 and September 1981
Attempts have been made to improve nozzle geometry in order to overcome the problems associated with orifice casting as shown in U.S. Pat. No. 4,290,476, issued March 23. A disadvantage of orifice casting is that the orifice measures the amount of molten metal that effectively defines the thickness of the strip. Moreover, a relatively high pressure head used to supply sufficient melt to the orifice is used, and for containing the melt,
The relatively small spacing from the casting wheel limits the thickness of the strip.

Thicker strips can be produced on a single quench surface, for example, by dipping a slow rotating quench wheel into a statically fed melt to solidify a much thicker strip. The melt solidifies on the surface of the wheel and continues to thicken at a determinable rate until it exits the bath or leaves the surface. The fresh supply of melt avoids the initiation of cracks, which is generally associated with limited layer solidification, as in orifice casting. Moreover, the extremely steep thermal gradient between the melt pool and the solidification front results in a more uniform internal structure and superior top surface quality. The disadvantage of such a dipping device is that it is difficult to prevent the molten metal from solidifying on the edge of the quench wheel which is slightly submerged,
This is due to the difficulty in having a tendency to cast channel-like structures. In addition, it is difficult to ensure uniform contact between the solidifying strip and the surface of the quench wheel as it enters the melt pool, which deteriorates the surface quality of the strip on the cast side. These problems cause variations in the thickness of the strip, resulting in thinner thicknesses where the intimate contact is reduced or eliminated.

Other direct casting methods have been proposed but have not developed into a practical method. On cooling, pouring the melt onto the top of a moving casting wheel produces strips of non-uniform thickness, weak edges and unacceptable quality. U.S. Pat. No. 9.93904, dated May 30, 1911, discloses an apparatus having a first melt vessel with a gravity outlet opening into the lower portion of a second tray-like vessel below the melt level. ing. The molten metal is second
It flows out of the container via overflow means which sends the melt to a casting wheel. US Patent No. 3381739, issued May 7, 1968
The publication discloses a method of forming a sheet or strip material by flowing a liquid around a wetted surface and filling the space to the moving casting surface for solidification with the liquid with the liquid.

What is needed is a useful method for commercial production of direct casting of strips that have surface qualities comparable to or better than conventionally produced strips. Direct casting method and apparatus are orifice type casting,
And should produce strips that are superior to other known direct manufacturing processes including dip casting, horizontal link belt quenchers and twin casting rolls. The purpose of this method and device is to overcome the drawbacks of the known direct casting processes. Further, there is a need for a method and apparatus for directly casting relatively thick strips on the order of 0.010 inches (0.0254 cm) or more and up to about 0.100 inches (0.254 cm) or less. In order to improve the surface quality and texture of the strip, it is desirable to minimize or eliminate the factors that contribute to shrinkage and cracking of direct cast strips. Further, a method and apparatus suitable for mass producing strips at low cost and facilitating the production of new alloys is desirable. Direct cast strips should have good surface quality, edges and texture and at least as good properties as conventional cast strips.

SUMMARY OF THE INVENTION The present invention is a method of casting molten metal directly into a continuous strip of crystalline metal, wherein the molten metal is drawn from a generally U-shaped structure at the exit end of a casting vessel to a continuous belt or casting adjacent to said structure. Pour on the casting surface like a wheel,
From the outlet end of the casting container, the molten metal is moved substantially upward through the outlet end at a predetermined interval, and the molten metal is a zone formed on the molten metal adjacent to the casting surface over the width of the U-shaped structure, A method of casting a molten metal directly into a continuous strip of crystalline metal, which is cooled by radiative heat transfer to a structure installed above.

The present invention also provides a casting surface for transporting the molten metal from the casting container and a U-shaped structure for flowing the molten metal to an adjacent casting surface at a predetermined distance in an apparatus for directly casting the molten metal into a continuous strip of crystalline metal. A casting vessel having an outlet end having a body and a cooling means for cooling the melt by radiative heat transfer in a zone formed over the width of the U-shaped opening and above the melt adjacent to the casting surface. Is an apparatus for directly casting a molten metal into a continuous strip of crystalline metal having a.

DESCRIPTION OF THE PREFERRED EMBODIMENTS For a better understanding of the invention, the casting apparatus on which the invention is based will first be described with reference to FIGS.

FIG. 1 shows a casting apparatus 10 in its entirety, which is used to produce a transfer vessel 12 and a casting vessel for casting molten metal directly on a casting surface 20 to produce a continuous product 15 in strip or sheet form. It has a supply tundish 14 for supplying molten metal to 18. Molten metal 19 is supplied from vessel 12 to tundish 14 and then to casting vessel 18 in a conventional manner. Hottie 16
Alternatively, any other suitable device may control the flow of the melt into the casting vessel 18, such as through the spout 17. The casting vessel 18 is shown to be substantially horizontal, with the casting vessel 18 having a receiving end and an outlet end disposed adjacent the casting surface 20.

Feeding of the melt 19 through the casting vessel 18 is accomplished by any suitable conventional method and, for example, in a vessel, tundish or melt pump apparatus. Vessel 12 and feed tundish 14 may be of any known design, but should be suitable for feeding the casting vessel with the appropriate amount of melt to produce strips on the quench wheel.

Also, casting surface 20 may be conventional, but may take the form of a continuous belt or casting wheel. Preferably,
Use a casting wheel. The composition of the casting surface does not appear to be critical to the invention, although some casting surfaces provide good results. The method and apparatus of the present invention uses copper, carbon steel and stainless steel casting surfaces. It is important that the casting surface be able to pass through the casting vessel at a constant rate and provide the desired quench rate in order to remove sufficient heat to solidify the melt in strips. Casting surface 20 is 20ft / min to 50 suitable for mass production of crystalline materials
0 feet (6.096m to 152.4m) / min, preferably 50
Feet / minute to 300 feet (15.24m to 91.44m) /
The casting vessel 18 can be passed at a rate of minutes (FPM). The casting surface 20 should be sufficiently cold to quench the melt to remove heat from the melt and solidify the crystalline form of the strip. The quench rate provided by the casting surface 20 of the apparatus 10 is less than 10,000 ° C / sec, and generally preferably less than 2,000 / sec.

Two important aspects of the casting surface are that it has a direction passing upwards in front of the outlet end of vessel 18 and that it has a free surface melt pool at the outlet end. The free surface of the melt pool at the outlet end 26 is essential for good top surface quality of the cast strip. "freedom"
Means that the top surface is not constrained by construction, i.e. it is not in contact with the container structure and is free to seek its own level between the receiving portion 22 and the outlet end 26. . Generally, the flow path is in the direction of metal flow when measured between the direction of flow of metal at the free surface of the melt at the exit end and the direction of movement of the casting surface at the free surface of the exit end of the casting vessel 18. It is oriented at a tilt angle θ of about 0 ° to 135 ° from the horizontal. For a casting wheel, the flow path on the casting surface is in contact with the free surface at the outlet end of the container 18. Preferably, the angle is between 0 ° and 45 ° from the horizon. For a casting wheel, the vessel is adjacent to a position within the upper quadrant of the wheel when the free surface of the melt is near the top of the casting wheel and the angle is at about 0 °.

Casting vessel 18 is integral to the method and apparatus of the present invention and is best shown in Part 2, which is an elevational view of vessel 18.
The casting vessel 18 is located adjacent to the casting surface 20, is preferably substantially horizontal and is constructed of the following insulating and refractory materials. This configuration is necessary to provide the desired flow of uniform and well formed metal to the casting surface 20. The container 18 has a receiving end 22 in the rear portion and an outlet end 26. Preferably, the receiving end 22 and the outlet end 26 have substantially the same cross-sectional area, or, when measured perpendicular to the direction of metal flow from the receiving end 22 to the outlet end 26, the outlet end. 26 has a larger cross-sectional area. The receiving end 22 is shown as deeper than the outlet end 26, for example to facilitate the reception of the molten metal 19 from the supply spout 17 and to create a flow of the molten metal to the outlet end 26.

The outlet end 26 of the container 18 has a bottom wall portion 28 as shown in FIG.
And a generally U-shaped structure formed by the sidewall 30. The side wall portion 30 may have a vertical inner wall inner surface 31, preferably the surface of the side wall 30 of the U-shaped structure.
The 31 is flared to open upwards to facilitate the flow of metal. This slight taper tends to improve the flow of metal from the outlet end 26, but too large a taper causes surface tension control loss and melt overflow. A taper of less than 10 ° per side, preferably 1 ° to 5 ° is provided.

The outlet end 26 has a bottom wall 28 having a generally flat inner portion having sufficient flow to provide a substantially uniform flow of metal from the outlet. Preferably, the length of the flat wall portion, as measured in the direction of metal flow, is at least equal to the depth of the melt pool to be contained at the outlet end 26. More preferably, the length to depth ratio is at least 1: 1 or higher. The outlet end 26 has uniform width and height dimensions throughout the length of the flat inner surface of the bottom wall 28 to create a uniform cross-sectional area at the end. The width of the outlet end 26, measured between the inside of the side wall 30 along the free surface of the molten pool, is about the same width as the strip to be cast. Preferably, the outlet end 26 is positioned adjacent to the casting surface 20 and the ends or edges of the side wall 30 and bottom wall 28 forming the U-shaped structure are substantially parallel to the casting surface. is there. To facilitate transfer flow between the receiving portion 22 and the outlet end 26, an intermediate portion leading between the receiving portion 22 and the outlet end 26 such that there is a substantially uniform flow at the outlet end 26. 24 should be provided. Preferably,
The intermediate portion 24 maintains a substantially uniform cross-sectional area throughout its length from the receiving portion 22 to the outlet end 26.
The intermediate portion 24 shown in FIG. 3 is from the receiving portion 22 to the outlet end 26.
And has a gradually increasing depth to maintain a substantially uniform cross-sectional area throughout its length, as shown in FIG. The intermediate portion 24 may include a tapered bottom wall 32 that gradually increases the depth of the container 18 from the receiving portion 22 to the outlet end 26. Similarly, the intermediate portion 24 may have at least one side wall 34 that widens outwardly to provide an increasing width from the narrow receiving portion 22 to the wide outlet end 26. FIG. 2 is a plan view of the casting container 18 showing the side wall 34 of the intermediate portion 24.

Also, in order to further facilitate the formation of a uniform flow in FIG.
It is shown that a weir or dam plate 36 may be used near where the 24 merges with the outlet end 26. The dam 36 should be made of a refractory or heat resistant material that resists corrosion by the melt. Kaowool refractory boards treated with dilute colloidal silica suspension have been found to be good. The dam portion 36 may extend over the entire width of the casting container 18 or may extend over a part of the width thereof. As shown in FIG. 2, the melt level in the receiving end 22 of the casting vessel 18 is preferably about the same as the melt level in the outlet end 26. The weir portion 36 facilitates the formation of a uniform and well-formed flow and is useful in blocking or constraining the flow to control the migration of surface oxides and slag.

Figures 2a and 2b show the case where the surface tension of the flowing melt is used to form the surface of the strip being cast. FIG. 2a is a detailed partial cross-sectional assembly view of the outlet end 26 adjacent the casting surface 20. Exit end
The melt flowing from 26 forms and maintains a meniscus 35 between the inner surface of the bottom wall 28 of the U-shaped structure and the casting surface. The surface tension forming the meniscus 35 forms the bottom of the strip 15 being cast. The surface tension of the free surface of the melt pool at the outlet end 26 is such that the curved portion 39 at the top of the melt in the U-shaped structure when forming the strip product.
To form.

FIG. 2b shows the outlet end 26 adjacent to the casting surface 20, with the molten metal 19 solidifying between them as seen from below the outlet end 26.
Is shown. The surface tension of the melt 19 forms a convex surface or meniscus 37 between the outlet end 26 and the casting surface 20 on the inner surface 31 of the side wall 30 near the lower wall 28.

Preferred examples of the casting container 18 are shown in FIGS. 4 and 5 in an elevation view and a plan view, respectively. Shown is a container 18 having a metal support shell 38, a refractory insulation 40, and a liner 42, which constitutes the inner surface of the casting container 18 and contacts the molten metal during casting. The container 18 should be made of refractory material that is both heat insulating and corrosion resistant to the melt. The casting vessel may be secured to some suitable table or device for orienting and positioning it on the casting surface or wheel 20 at the desired casting location. The outlet end 26 of the casting vessel 18 should have an outer wall 30 and a front surface or edge 33 of a bottom wall 28 forming a U-shaped structure that matches the contours of the casting surface. This can be done by using a 60 to 100 grid silicon carbide grinding paper held between the casting surface and the container assembly and rubbing the container 18 with this grinding paper to create edges parallel to the wheels. .
Next, the front surface 33 of the casting container 18 is brushed with zirconia cement and dried before casting.

4 and 5 show a preferred embodiment of the casting container 18 of the present invention, which embodiment has a width of 4 inches (10.16c).
m) and cast strips up to about 13 inches (33.02 cm), and also cast strips up to 48 inches (121.92 cm) wide. The metal support tube 38 is a heat insulating layer
It can be used depending on the type of material used for 40. Thermal insulation layer 40
Is preferably a foamed ceramic bonded insulation that requires an external support, such as a metal support tube 38. As a change example,
The barrel 38 is not required if standard refractory bricks or blocks are used and joined to the desired shape and then engraved to achieve the desired inside and outside dimensions. Alternatively, the container 18 may be a one-piece container formed from a castable ceramic material. The liner 42 provided on the inner surface of the casting container 18 is also made of a heat insulating refractory material that is resistant to the molten metal. Adiabatic blanket of high alumina fiber-silicate composition, such as a material named Fiberbex, saturated with a dilute colloidal silica suspension, formed in a casting vessel 18 and then dried prior to actual use. Was found to be useful.

4 and 5 also show a rear overflow element 44, which has a rear beveled surface 45 extending from the inner surface of the casting vessel 18 to the bottom wall of the vessel 18. Overflow element 44
The height determines the maximum depth of the molten metal contained in the receiving end 22 and thus the depth of the molten metal in the outlet end 26 of the casting vessel 18. The overflow element facilitates control of the thickness of the casting strip and the melt level of the casting vessel 18 which is essential for quality control.

Also shown in FIG. 4 is a casting container 18, which may optionally have a cover assembly 46 near its intermediate portion 24. The cover 46 has downwardly extending walls 48, 50 joined by a bottom surface 52. Wall extending downstream
48 and 50 are similar to the weir shown in FIG. The cover 46 is generally constructed of refractory insulation that is resistant to molten metal. The cover 46 includes a liner 42, a fireproof heat insulating layer 40, and a metal outer cylinder 18, and has the same configuration as the casting container 18. The presence of the cover is useful for retaining the heat of the melt in the casting vessel 18, but the presence of the cover allows the receiving end 22 and the outlet end to maintain the free surface of the pool in the outlet end 26. It is important that the molten metal in part 26 not come into contact.
Also, the cover has a rear receiving part to maintain a protective atmosphere.
It may extend over part or all of 22.

FIG. 6 shows that the outlet end 26 of the container 18 adsorbs the molten metal by radiative heat transfer in a zone adjacent to the casting surface 20 over the width of the U-shaped structure at the outlet end and above the molten metal. Figure 3 shows a direct casting device according to the invention with a device for creating a non-oxidizing atmosphere in said zone, incorporating cooling means for cooling.

Means for radiatively cooling the melt in the zone around the U-shaped structure melt at the outlet end 26 provides a coolant in the vicinity of the zone to facilitate heat removal from the top surface of the melt. It is good to include that.

Coolant may be supplied by a series of tubes 54 positioned above the melt to remove radiant heat from the melt. Water or other fluid may be used as the coolant. A cover is preferably provided having a series of water cooled tubes 54 sealed to the top of the casting vessel with refractory and cement. Radiative cooling of the top surface of the melt as it flows from the U-shaped structure in the outlet end 26 onto the casting surface enhances the cooling of the top surface of the solidifying melt to accommodate the growth of the dendrite structure of the strip. This improves the quality and texture of the as-cast strip top surface.

It should be noted that the apparatus for creating a non-oxidizing atmosphere provides a protective cover or blanket of inert or reducing gas in the zone around the melt of the U-shaped structure at the outlet end 26. These gases minimize or prevent the formation of slag and oxides (which are cast into the cast strip) on the top surface of the melt. The non-oxidizing atmosphere may be a stationary atmosphere or a recirculating atmosphere. Preferably. A non-contacting cover and at least one gas nozzle or series of nozzles across the zone above the molten pool at the outlet end 26 of the casting vessel 18 provide a continuous flow of inert or reducing gas in the direction opposite to the direction of the cast strip. Preferably, the gas is introduced so as to impinge in a zone above the top of the molten pool where strips are emerging. In this embodiment, a protective cover may be provided to seal the zone above the pool of molten metal containing the blanket of inert or reducing gas, said inert or reducing gas pushing the oxide away from the strip forming. Directed into the gas stream. A series of narrow gas nozzles 56 are positioned along the width of the cast strip so that the gas stream or jet impinges on the zone where the strip emerges from the liquid pool. The nozzle 56 is oriented at an angle to the plane of the shaped strip, preferably about 20 ° to 30 °, opposite the casting direction of the strip. The gas blanket may be a gas selected from the group consisting of hydrogen, argon, helium and nitrogen to minimize oxides formed during casting. The velocity of gas from nozzle 56 should be very low. This is because at high speeds, the top surface of the molten metal is disturbed and damages the cast strip.

The non-contact cover, which seals the zone above the melt at the outlet end 26, has cooling means for removing radiant heat from the melt and a non-oxidizing atmosphere device. Preferably, the cover is a series of water cooling tubes 54.
And a series of gas nozzles 56. The inert gas is cooled by tube 54 which further facilitates the removal of radiant heat.
The cover, which includes cooling tubes 54, seals the zones and reduces the formation of oxides or slag that adhere to the strip product.

In the operation of the casting apparatus of the present invention, the vessel 12, the tundish 14 and the casting vessel 18 are preheated to the working temperature prior to introducing the molten metal into the casting vessel for producing the strip material. Any conventional heating device is suitable and can be used. Uses an air-acetylene or air-natural gas heating lance which is positioned at the receiving end 22 and constitutes a preheat front cover for the leading edge of the casting vessel U-shaped structure located adjacent the casting surface 20. . The standard preheating temperature for casting molten stainless steel is 1900 ° F to 2000 ° F (1037.8 ° C).
To about 1093.3 ° C) is preferable. After the desired minimum preheat level is reached, the heating lance is removed and the container 18 is positioned adjacent the casting surface at a predetermined spacing, such as between 5 mils (0.0127 cm) and 20 mils (0.0508 cm).

To begin the process of casting the alloy directly from the melt into a continuous strip, the melt 19 is fed from a bulk transfer vortex or vessel 12 to a feed tundish 14 and then to a casting vessel 18 oriented substantially horizontally. The flow of molten metal from the feed tundish 14 to the casting vessel 18 may be regulated by a valve device such as a stopcock 16 via a spout 17 to the rear feeding portion or receiving end 22 of the casting vessel 18.
When the container 18 begins to fill with molten metal, the molten metal begins to flow in the direction toward the outlet end of the container and then through the intermediate portion 24 and outlet end 26 as shown in FIG. The casting vessel 18 can be flushed to supply molten metal to its outlet end 26. The casting vessel 18 has weirs 36 as shown in FIG. 2 to slow or block the flow of the melt 19 to facilitate a uniform and well-formed flow at the outlet end 26. Good. The melt is preferably the receiving end 22
To maintain a substantially uniform cross-sectional area of flow through the outlet end 26. Generally, the outlet end 26 is wider than the receiving end 22,
The figure-shaped structure has a width approximately equal to the width of the strip to be cast. The casting vessel 18 has a casting volume with a tapered and flared intermediate portion. The casting vessel 18 is designed to prevent cross flow of molten metal therein and to form a uniform turbulence from the outlet end 26 across the width of the U-shaped structure at the outlet end 26, and thus The flow formed in the stream has various streamline velocities in the direction of flow from the receiving end 22 to the outlet end 26. The melt level at the outlet end 26 is about the same as the melt level at the receiving end 22, but the depth of the melt is shallow at the outlet end. The molten metal continues to flow from the outlet end 26 onto the moving casting surface 20 so that a substantially uniform flow of molten metal is provided to the casting surface 20 across the width of the U-shaped structure at the outlet end. The melt at the outlet end 26 has a top surface tension and the melt exiting the opening has an edge surface tension, which partially forms the ends and edges of the cast strip 15, respectively. The bottom surface is formed from surface tension in the form of a meniscus between the bottom inner surface of the U-shaped structure and the casting surface.

By speculation, it is believed that solidification of the melt leaving the outlet end of the container 18 begins with the melt contacting the casting surface as it leaves the bottom of the U-shaped opening at the outlet end 26 of the container 18. It is solidified from the pool of molten metal available on the casting surface at the outlet end of the strip container 18, and the outlet end 26 of the container 18
The thickness of the strip, which is solidifying until leaving, is continuously imparted with excess melt. Such a melt pool forms a significant portion of the strip thickness when in contact with the moving casting surface 20, with only a small portion of the strip thickness adjacent the top curvilinear surface tension portion 39. It is believed to result from the solidified melt as it is drawn from. It is estimated that more than 70% of the thickness of the strip, and perhaps more than about 80%, originates from the melt pool supplied adjacent to the meniscus 35. The melt solidifies from the bottom of the U-shaped structure at the outlet end 26 of the vessel 18 from the bottom of the melt supplied to the casting surface.

The casting surface 20 passes in front of the casting vessel 18 upwards from the bottom of the U-shaped opening of the outlet end 26 to the top of the opening of the opening.

The position of the container 18 with respect to the casting surface 20 and the velocity of the casting surface are predetermined factors to achieve the quality and size of the cast strip. If the casting surface 20 is a casting wheel, the container 18 is preferably positioned on the upper quadrant of the casting wheel.

The method of the present invention makes important adjustments to several factors which result in 0.01 to 0.06 inch (0.0254 cm to 0.1524) with good surface quality, edges and texture.
It is possible to cast metal strips with desired dimensions in the cm) range. Adjusting the flow rate of the molten metal onto the casting surface, the speed of the casting surface, the solidification from the bottom of the molten metal pool, and the adjustment of the depth of the molten metal in the adjusting pool to maintain the surface tension of the molten metal and the distance from the casting surface Is an important correlation factor.

The following examples are presented to facilitate an understanding of the present invention.

As a whole, it has a structure as shown in FIG.
A casting container having a Kaowool refractory / alumina foam refractory insulation 40 therein was constructed. Saturated with dilute colloidal silica suspension, and then dried, prior to use, liner 42 was formed at 8 lbs / cubic foot (128.15 kg / m ³ ) to 0.5 inch (1.27 cm) thick. . The outer dimensions of container 18 were approximately 15 inches (38.1 cm) long and 18 inches (45.72 cm) wide at the exit end, with a slightly increased cross-sectional area to exit end 26. A single dam plate 36 was positioned near the outlet end 26 and joined between the sidewalls of the container 18. Each inner surface 31 of the side wall 30 was tapered by about 3 ° and was divergent. The casting vessel was set at about a 0 ° angle about a 35 mil (0.0889 cm) angle about the free surface of the melt near the top of the casting wheel.
According to the invention, Type 304 alloy 500 lbs (226.5 Kg)
Was cast on the casting surface of a low carbon steel seamless tube with an outer diameter of 12.75 inches (32.385 cm), a wall thickness of 0.375 inches (0.9525 cm) and a width of 48 inches (121.92 cm), and was internally water spray cooled. About 200 FPM at the start of casting the casting wheel
Spin at (60.96m / min) for 10 to 15 seconds to facilitate flushing of the initial hot water flow, then 100FPM of flow duration
It decelerated to (30.48m / min). Approximately 2 molten metal at the outlet end 26
Inch (5.08 cm), receiving end 22 2.75 inches (6.98c)
m) was maintained.

As shown in FIG. 6, the container 18 has a cover provided with a radiation cooling device and a helium atmosphere providing device. Cooling was provided by circulating water at approximately 3 gallons (11.3559) / min through a 0.375 inch (0.9525 cm) outer diameter copper tubing.

The as-cast strip was about 13 inches (33.02 cm) wide, had a uniform thickness of about 45 mils (114.3 cm), and had a good, smooth, crack-free top surface quality. . The as-cast strip is then pickled with nitric acid / hypofluorous acid,
Cold rolled to about 50% reduction, annealed at 1950 ° for 5 minutes,
It was pickled again in a similar manner, then conventionally processed by cold rolling to 5 mils (0.0127 cm) and annealed. The room temperature mechanical properties of the annealed as-cast samples are shown below in comparison with typical properties of conventionally manufactured type 304 alloy annealed hot rolled bands.

Type 304 alloy manufactured by conventional method has a tensile strength of 101.1KS
I, has a typical or average room temperature mechanical properties of an annealed hot-rolled band with a yield strength of 43.8 KSI and an elongation of 57% at 2 inches (5.08 cm).

FIG. 7 is a micrograph of a cast strip of the present invention showing a typical internal structure of a type 304 alloy. Type 30
The 4 alloy is shown at 100 times and shows a typical cast structure of small cylindrical cells oriented in the thickness direction of the strip, ie from the top surface to the bottom surface. This direction corresponds approximately with the direction that heat is taken from the strip as it solidifies. The method and apparatus of the present invention can control the growth of dendrite texture in strips and process conventional strips into finished strips that have properties comparable or better than conventional manufactured strip products. Produce as-cast strip that can.

FIG. 8 shows a typical structure of a conventionally produced hot rolling band of type 304 alloy at 100 times magnification.

It can be seen that with the method and apparatus of the present invention, as the strip product size increases and the strip width increases, the strip structure and quality become uniformly better. Edge curl tendency in strip products cast from 4 to 6 inches (10.16 cm to 15.02 cm) wide no longer appears to exist at widths as wide as 13 inches (33.02 cm). The method and apparatus of the present invention provides a simple, direct method of casting a continuous strip or sheet of crystalline metal from the melt. The problems of solidification shrinkage and cracking of the strips are eliminated, resulting in relatively thick strips of quality comparable to or better than conventional manufacturing methods.

The method and apparatus are useful with a variety of metals and alloys, including stainless steel and silicon steel.

[Brief description of drawings]

1 is a schematic view of a strip casting apparatus; FIG. 2 is a cross-sectional elevation view of a casting container; FIG. 2a is a detailed elevation view of FIG. 2;
Figure is another detail of Figure 2; Figure 3 is a plan view of the casting vessel of Figure 2; Figure 3a is an end view of the casting vessel of Figure 3; Figure 4 is a cross-section of another casting vessel. FIG. 5 is a plan view of a preferred embodiment of the casting vessel of FIG. 4; FIG. 6 is an enlarged elevation view of a preferred embodiment of the outlet end of the casting vessel of the present invention; Photomicrograph of a typical Type 304 alloy as-cast strip of the invention; FIG. 8 is a photomicrograph of a conventional process hot-rolled band of a typical Type 304 alloy. 10 …… Casting device, 12 …… Transfer container 14 …… Supply tundish, 16 …… Hottie bar 18 …… Casting container, 19 …… Melting surface 20 …… Casting surface, 22 …… Receiving end 24 …… Intermediate Portion, 26 …… Exit end 28 …… Bottom wall portion, 30 …… Sidewall portion 32 …… Tapered bottom wall, 36 …… Weir portion 38 …… Outer cylinder, 40 …… Fireproof insulation 42 …… Liner

Front Page Continuation (72) Inventor Jiyon Dana Naumann Pennsylvania, USA 15065 Natrona Heights Kingston Drive 2737 (56) References JP-A-4-62824 (JP, A) JP-A-6-41019 (JP, A)

Claims (5)

(57) [Claims] 1. A method of casting molten metal directly into a continuous strip of crystalline metal, the molten metal being from a substantially U-shaped structure at the outlet end of a casting vessel,
It is poured onto a casting surface such as a continuous belt or a casting wheel adjacent to the structure, and the casting surface is moved substantially upward from the outlet end of the casting container through the outlet end at a predetermined interval, and the molten metal is U-shaped. Over the width of the structure, in the zone formed on the molten metal adjacent to the casting surface, installed above the molten metal,
A method of casting a molten metal directly into a continuous strip of crystalline metal, cooling by radiative heat transfer to a cooling structure having at least one tube supplying a circulating coolant. 2. A method according to claim 1, wherein a non-oxidizing atmosphere is created in the zone. 3. A device for directly casting molten metal into a continuous strip of crystalline metal, a casting surface for transporting the molten metal from the casting vessel, and a U-shaped structure for flowing the molten metal to an adjacent casting surface at a predetermined distance. A casting vessel having an outlet end with a body and a circulation for cooling the melt by radiative heat transfer in a zone formed over the width of the U-shaped opening and above the melt adjacent to the casting surface An apparatus for directly casting a molten metal into a continuous strip of crystalline metal, the cooling means having at least one tube supplying a coolant. 4. Having means for sealing said zone,
The device according to claim 3. 5. An apparatus according to claim 3 including means for creating a non-oxidizing atmosphere in said zone.