JPH028817B2 - - Google Patents

Abstract

An oscillating cooled mold assembly for the continuous high-speed casting of metallic strands, (12) especially upcasting strands of copper alloys such as brass, has a hollow die (112) in fluid communication with a melt (14) typically held in a casting furnace (16). coolerbody surrounds the die in a tight-fitting relationship to form a solidification front in the melt as it advances through the casting zone of the die. During assembly, the die is preferably slip fit in the coolerbody (103). A shoulder on the die engages a lower face of the coolerbody (103) and, together with a small irregularity on the upper coolerbody wall, prevents any axial movement of the die before it thermally expands against the coolerbody. An insulating member (118) located between the die and the coolerbody and below the solidification front fixes the location of the front within a dimensionally uniform area of the die. The insulating member is preferably a ring of a material such as casting silica that has a low coefficient of thermal expansion, a low porosity, and is highly resistant to thermal shock. The insulating member (118) also preferably creates a steep longitudinal temperature gradient at its upper end to promote a high cooling rate over a relatively short casting zone. An insulating hat encloses the coolerbody, allowing it to be immersed in the melt and preferably deeply immersed to a level above the casting zone The strand or rod formed from the solidified melt is pulled through the die while the mold oscillates in a direction substantially parallel to the direction of travel of the rod.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the casting of metal strands, and more particularly to a system using a cooled vibratory mold assembly for continuous high-speed casting of strands of copper and copper alloys, including brass. It is.
The present invention is disclosed in Japanese Patent Application No. 54-96647 (Japanese Patent Application No. 55-61357).
This invention relates to an improvement of the invention related to casting of metal strands described in the specification of No.

It is well known in the art to cast metal strands of variable length from a melt by drawing the melt from a cooled mold. The mold generally includes a die made of a refractory material, such as graphite, which is cooled by a surrounding water jacket. U.S. Pat. No. 3,354,936 describes a cooled mold assembly sealed to the bottom wall of a melt vessel for, for example, downcasting large billets. The melt is forced through the mold by gravity.
However, with downcasting, there is a risk of melt bulge or "breakout" and the melt vessel must be emptied or tipped in order to repair or replace the mold or casting die. It won't happen.

Horizontal casting methods using chilled molds have also been attempted. In addition to downcasting breakout and replacement problems, gravity can cause uneven solidification, which can result in uneven cross-sections or poor surface quality. This means that ivy castings can be made.

Various devices for upcasting have also been used. Early work is described in US Pat. No. 2,553,921 to Jordan and US Pat. No. 2,171,132 to Simons. Gildan's patent utilizes a water-cooled metal "molded pipe" with a ceramic exterior lining that is immersed in the melt. In practice, no suitable metal has been found for molded pipes, castings are subject to non-uniform cooling, and the gap between molded pipe and lining caused by the difference in thermal expansion coefficients allows for condensed metal vapor to form. Accumulate. The Simon patent also uses a water-cooled "casing", but the casing is mounted above the melt and a vacuum is required to draw the melt into the casing. A coaxial refractory casing extension extends into the melt. This refractory extension is necessary to prevent "pine rooming", i.e. the formation of solid lumps of metal with a diameter larger than that of the cooled casing. however,
In the Gijordan patent, condensed metal vapor accumulates in the thermally generated gap, in this case between the casing and its extension, thereby degrading the surface of the casting or Casting stoppage may occur.

U.S. Pat. No. 3,746,077 and U.S. Pat. No. 3,872,913 disclose relatively recent upcasting devices and techniques; the latter patents require only the tip of a "nozzle" to be placed in the melt. eliminates problems associated with differential thermal expansion. A water-cooled jacket surrounds the top of the nozzle. Since the surface of the melt is below the cooling zone, a vacuum chamber is required at the top of the nozzle to draw the melt into the cooling zone. However, the presence of this vacuum chamber limits the rate of strand withdrawal and requires sealing.

According to the aforementioned U.S. Pat. No. 3,746,077, the need for a vacuum chamber is eliminated by submerging the cooling jacket and a portion of the enclosed nozzle in the melt. The immersion depth is sufficient to drive the melt into the solidification zone, but it is not immersed deeply. The jacket and the interface between the jacket and the nozzle are protected against melt by a surrounding thermal insulation lining. The lower end of this lining is in contact with the lower outer surface of the nozzle;
Prevents melt from flowing directly into the cooling jacket.

All of the systems described above are generally characterized as "closed" molds that place the liquid metal in direct communication with the solidification front. The cooled mold is normally fed from an adjacent vessel filled with melt. in contrast,
In "open" mold systems, the melt is conveyed directly to the mold, usually by a delivery tube, where it is cooled very rapidly. Open mold systems are commonly used when downcasting large billets of steel and often aluminum, copper or brass. However, open mold casting has not been used to form products with small cross sections because it is very difficult to control the liquid level and thus the position of the solidification front.

A problem that occurs in closed mold casting processes is thermal expansion of the casting die bore between the beginning of the solidification front and the point of complete solidification, referred to as bellowing or "bell-mouthing." Due to this condition,
An enlargement of the cross-section of the casting takes place, which is wedged into the narrower part of the die. This wedged area can rupture or form a "skull" that is difficult to move. This skull can either stall the strand or pick up on the die and create flaws in the surface of the casting. Therefore, it is important to maintain dimensional uniformity of the die bore within the casting area. The above U.S. patent no.
In the systems of No. 3,872,913 and No. 3,746,077, these problems were partially attributable to a relatively gradual vertical temperature gradient along the nozzle that resulted in a moderate cooling rate to form a generally flat solidification front. can be controlled by With this gradual temperature gradient, castings of acceptable quality can only be produced at relatively slow speeds, typically 5 to 40 inches per second.

Another significant problem when casting with chill molds is metal vapor condensation. Condensation is particularly troublesome in the case of casting brass containing zinc or other alloys containing elements that boil at temperatures below the melting temperature of the alloy. Zinc vapor easily penetrates materials commonly used to form casting dies as well as common insulation materials and can condense into a liquid in critical ranges. Liquid zinc on the die in the vicinity of the solidification front can boil on the surface of the casting, resulting in gas-containing surface defects. These problems prevent current casting equipment and technology from commercially producing high quality brass strands at high speeds.

The method by which the casting is pulled from the chill mold is also an important aspect of the casting process. A periodized pattern of forward pull strokes followed by rest periods has been used commercially with the mold unit described in the above-mentioned U.S. Pat. No. 3,872,913. US Pat. No. 3,908,747 describes the skin of a casting.
A controlled retraction stroke is disclosed to prevent casting stoppage and to compensate for shrinkage of the casting within the die as it cools. GB 1087026 discloses a retraction step for partially remelting a casting. U.S. Pat. No. 3,354,936 discloses a relatively long advance stroke;
A pattern of subsequent stopping of the casting operation and a relatively short retraction stroke is disclosed. This pattern is used when downcasting large billets because it prevents reverse segregation. However, in both of these systems, stroke speeds and net casting speeds are slow. For example, in the system of US Pat. No. 3,354,936, the forward stroke lasts 3 to 20 seconds and the reverse stroke lasts 1 second, so the net speed is 13 to 15 inches per minute.

To provide a stripping action and to facilitate the movement of the newly cast rod through the mold, and more importantly, if the advancement speed of the mold at one point in the cycle is greater than that of the rod being cast. It is known to vibrate continuous casting molds to prevent the formation of tears in the solidifying skin. Further, by vibrating the mold to effect the casting process, the rod can be withdrawn from the mold at a constant speed, thereby facilitating post-casting process operations, such as conversion of the rod into strip. A particularly preferred design of a vibratory mold assembly is disclosed in U.S. patent application Ser. has been done.

It is therefore a primary object of the present invention to continuously produce high quality metal strands, especially strands of copper and copper alloys including brass, at production rates many times faster than previously achievable in closed mold systems. An object of the present invention is to provide a cooling mold assembly and a casting method for casting.

Another object of the invention is to provide a mold assembly that vibrates in substantially the same direction as the bar being cast with little or no lateral movement.

Yet another object of the present invention is to provide a cooled mold assembly for upcasting that is vibrated and used immersed in a melt.

Yet another object of the present invention is to provide a mold assembly that balances the steep temperature gradients experienced by a casting die, particularly at the lower end of the solidification zone, thereby preventing skull formation or dimensional irregularities in the casting zone. The goal is to eliminate loss due to uniformity.

Yet another object of the invention is to provide a method of drawing castings using the mold assembly described above for producing high quality strands at extremely high speeds.

Yet another object of the present invention is to provide a mold assembly having the above-mentioned advantages of being relatively low in manufacturing cost, convenient to maintain, and durable.

A vibration-cooled mold assembly for high-speed continuous casting of metal strands has a hollow die made of refractory material. A melt, usually copper or a copper alloy such as brass, is in fluid communication with one end of the die. The cooling body, preferably of the water-cooled type, surrounds the die in a close fitting relationship. The cooling body has a high cooling rate that creates a solidification front in the casting region of the die spaced from the end of the die adjacent to the melt.
Means are provided for withdrawing the melt from the mold assembly for solidification of the rod or strand. The mold assembly is supported for vibration in a direction substantially parallel to the direction in which said rod moves through the mold and is advanced and moved by means for vibrating the mold assembly as said rod or strand is advanced. The effects of both casting processes of retraction occur. By vibrating the mold as the rod or strand is withdrawn at a constant speed, the relative movement between the mold and the rod can be controlled over a wide range. A means is provided for the chill mold to deliver cooling fluid during vibration.

The above-mentioned patent application No. 1984-96647
In the invention relating to the method for casting metal strands described in the specification of No. The formation of the epidermis is controlled. However, such a method causes distortion in the strand, and control of this distortion is extremely difficult. In the method of the present invention, by vibrating the mold when the rod or strand is pulled out of the metal melt at a constant speed, distortions in the strand, which are difficult to control, can be prevented and the entire casting process can be controlled. becomes even easier.

In a preferred embodiment of the invention, the coolant manifold extension assembly is in communication with the coolant and supplies coolant to the coolant. The manifold extension assembly is also attached to a support manifold that supplies coolant to the extension assembly. The insulating cap surrounds the cooling body and manifold extension assembly and thermally isolates them from the metal melt. The insulating cap is connected to the support manifold by spring biased attachment means. The manifold extension assembly consists of three concentric tubes forming two annular elongated passageways between them, one of which is used to supply coolant to the cooling body and the other passageway. is used to receive coolant from the cooling body. The two internal tubes are a slip fit into O-ring gland seals in the support manifold.

The means for effecting mold vibration includes at least one hydraulic actuator controlled by a servo valve and computer means. The mold vibration waveform is defined to provide unlimited variation in strip speed, return speed, and rest period. This is particularly useful in determining optimal mold motion programs for various casting alloys.

The die preferably has a longitudinally uniform cross section. The die may have a slightly upwardly tapered or stepped structure on its inner surface. Preferably, the die is a slip fit within the cooling body to facilitate replacement. Before the die thermally expands relative to the cooler body, the die has a mating coolerbody wall near the top stepped outer surface that engages the lower surface of the cooler body.
A slight upset in the center provides restraint against axial movement. In a preferred embodiment,
A metal foil sleeve is placed between the outer insulation member and the counterbore to facilitate removal of the insulation.

The cooling body preferably has a double-walled construction, between which an annular space is formed. The inner wall adjacent the die is preferably formed from a high quality ingot of age hardened chromium copper alloy, and the outer sleeve is preferably formed from stainless steel.
The inner and outer walls or "body" are preferably joined at their lower ends by copper/gold braze joints. The water is typically circulated at a temperature range and flow rate such that the melt advancing through the die is cooled at a high cooling rate while avoiding condensation of water vapor onto the mold assembly or casting. Preferably, the vapor shield and gasket are located between the immersed end of the cooling body and the surrounding insulation cap.

The above objects and configurations of the present invention will become apparent to those skilled in the art from the following description with reference to the accompanying drawings.

FIG. 1 shows a suitable installation according to the invention for the continuous production of metal strands of variable length by upward casting from a cooling mold. Four strands 12 are simultaneously cast from the molten metal contained in the casting furnace 16. The strands described above can have various cross-sectional shapes, such as square or rectangular, and various diameters; The explanation will be based on the assumption that it is a stick with a

Referring to FIG. 1, the strand 12 is
It is cast in four cooled mold assemblies 18 mounted on four vertically movable carriage devices 20. Those strands are pulled out by pulling machine 2
2 and directed from the mold assembly at a constant speed to a pair of booms 24, 24';
It is then guided by the booms 24, 24' to four injection coiler devices 26, where it is assembled into a coil. Each boom 24 is connected to the duct 2
It is hollow to guide the cooling air supplied by 8 over the length of the boom.

The melt is produced in one or more melting furnaces (not shown) or a combined melting and containment furnace (not shown). Although the present invention is suitable for producing continuous strands formed from a wide variety of metals and alloys,
In particular, it is directed to the production of strands made of copper alloys or primarily brass. The melt is transported from the melting furnace to the copper casting furnace 16 by a ladle 30 supported by an overhead crane (not shown). Preferably, the ladle has a tee-pot type flow opening or spout that supplies the melt with a minimum of foreign matter such as cover and dross. For ease of transportation, the ladle is rotatably supported on a cradle 32 on a casting platform 34. The melt is introduced into the casting furnace 16 from the ladle 30 by a ceramic casting cup 36. The outlet end of the casting cup 36 is located below the casting furnace cover and at the point of melting from the mold assembly 18. Unlike batch casting, in continuous manufacturing, additional melt is added when the melt is approximately half full in the casting furnace, and the melt is chemically and thermally mixed.

The casting furnace is equipped with a set of load cells 38a (FIG. 10) for sensing the weight of the casting furnace and its contents.
It is supported on a vacuum type scissor type lifting/lowering dolly device 38 equipped with. The output signal of the load cell 38a is
Conditioned to control the raising and lowering of the furnace;
This allows automatic control of the level of melt to the cooling body. As best seen in FIG. 10, the casting furnace has a lower limit position with the mold assembly 18 spaced above the upper surface of the melt 14 when the furnace is full, and a lower limit position with the mold assembly 18 spaced above the upper surface of the melt 14 when the furnace is full. It is movable to and from an upper limit position (shown in phantom) adjacent to the bottom surface. The height of the casting furnace is constantly adjusted during casting to maintain a predetermined depth of immersion of the mold assembly 18 into the melt. In the lower end position, the mold assembly is accessible for replacement or repair after the casting furnace has been moved out of orbit.

It should be noted that this manufacturing equipment typically includes backup level controls such as probes, floats, etc., and manual periodic measurements made using immersion wires and the like. these,
Alternatively, other commonly used level measurement and control systems may be used as the primary system in place of the load cell.
Additionally, although the invention has been described with respect to a stationary mold assembly and a movable casting furnace, other arrangements may be used. The casting furnace can be maintained at the same level and melt may be added periodically or continuously to maintain this same level. An alternative method involves very deep immersion so that no level control is required.
An important advantage of the present invention is that this deep immersion is possible. Each of these devices has advantages and disadvantages that are readily apparent to those skilled in the art.

Casting furnace 16 is a 38 inch coreless induction electric furnace with a cast alumina lining that is heated by a power source. A furnace of this size and type can accommodate approximately 5 tons of melt. The furnace 16 has an overflow and pouring ladle 42 (first
0).

Referring again to FIG. 1, the drawing machine 22
has four pairs of opposing pinch rolls 44 each frictionally engaged with one strand 12. The rolls 44 are fixed on a common shaft driven by a servo-controlled reversible hydraulic motor 46. Motor 46 is driven by a commonly used variable displacement, constant pressure hydraulic pump system that generates pressures up to 3000 pounds per square inch. A commonly used electronic programming device (not shown) programs the signals that control the operation of the motor 46 through a conventional servo system. The program also includes a programmed startup routine that gradually increases the withdrawal speed. The drive rolls 44 can be separately spaced from selected strands 12 without interrupting the advancement of other strands.

Referring to FIG. 2, mold assembly 18 is shown in furnace 1.
6 is immersed in the melt 14 contained in the melt 14. FIG. 2 shows protective cone 48 dissolving after assembly 18 is immersed in melt 14. FIG. Protective cone 48 is typically made of copper and takes less than a minute to completely dissolve. The purpose of the protective cone is to prevent dross and other impurities from entering the die during dipping.
The purpose is to prevent the intrusion into 12. Once the assembly is immersed in the melt and the cone collapses, molten metal is drawn into the assembly 18. The process is started by first inserting a solid starter rod (with a bolt on its end) into the melt from the top of the assembly via die 112. The molten metal solidifies on the bolt and follows as the rod is pulled through the die 112, solidifying along the way. After the solidified rod or strand 12 passes through the pinch rolls 44, the starter rod (along with a small portion of the strand 12) is cut from the remaining portion of the strand 12. Once strand 12 is formed from melt 14, it is continuously drawn off at a constant speed by one or more pairs of pinch rollers 44. In this manner, strand 12 is continuously transferred from the melt in the direction indicated by arrow 52 at a constant rate (typically 200-400 inches/minute). During the migration of the strands 12, the entire assembly 18 vibrates vertically. Basically, the assembly 18 is connected to a carriage device 20 for generating controlled vibrations.

The chill mold assembly 18 is cooled during vibration by coolant supplied via a flexible tube 56 to a manifold 54 mounted to the carriage assembly 20. The coolant supply system is shown in Figures 3 and 4.
Particularly described in connection with the figures.

Although the manufacturing facility of FIG. 1 uses four independently vibrating mold assemblies 18 to produce four strands 12, other numbers of mold assemblies may be used in tandem to produce four strands 12. It should be pointed out that it can also be used without (in series).

As mold assembly 18 vibrates during the casting process, large dynamic loads are generated that must be accommodated by its support structure. A superstructure capable of withstanding this load with minimal deflection will now be described in detail in connection with FIGS. 2 and 3. Referring first to FIG. 3, the entire support structure is a rigid steel box. Vertical loads are applied to steel I-beam columnar structural members 58, 60,
62 and 64. columnar member 58,
60, 62, 64 are horizontal steel I-beams 6
6, 68, 70 and 72. Horizontal members 66, 68, 70, 72 and 7
4 is preferably welded to the columnar members 59, 60, 62 and 64. Horizontal I-beams 66, 68, and 70 are oriented so that their flange faces extend vertically for maximum strength in supporting vibration-induced loads. Beams 72 and 7
4 are further strengthened by angle beads 72a and 74a welded to these beams. Beams 66 and 70 are vertically reinforced by bracing beams 75, 76, 78 and 80, also made of steel. Steel beams 82 and 84 strengthen the structure at the bottom.

The carriage structure is mounted to angle pieces 72a and 74a which generally support the carriage via horizontal I-beams 72 and 74.
The carriage load path is the beam 86, 88, 78,
The frame base is reached via 80, 75 and 76. Steel I-beams 89 and 90 are welded between horizontal beams 68 and 72. These beams 89 and 90 are vertical I-beams 91 and 92.
and horizontal I-beams 93, 94 and 95 supporting a vibrating carriage support superstructure. Beams 93 and 95 are welded to a steel I-beam 74 that connects the tops of columnar beams 60 and 64. This structure consists of backing I-beams 86 and 8.
8 provides further rigidity.

Carriage apparatus 20 (FIG. 2) is shown in more detail in FIG. 13. This device 20 consists of steel angle plates 201 and 2 welded to a bottom plate 203 and a back plate 205.
Consists of 02. The top plate 207 is connected to the back plate 205 and the angle plate 201.
and 202 to form a structure. Approximately 1
Inch thick plates 201 and 202 are lightened by holes 209 and 210, respectively.

The carriage device 20 includes a bottom plate 203
Bolt hole 211a (first hole) surrounding inner hole 213
3) by passing the bolts through the manifold 54.
(Figure 2) is supported. Holes 213 allow the casting strand to pass on its way to pinch rollers 44 (FIG. 2).

Referring to FIGS. 13 and 14, carriage apparatus 20 is moved vertically by rails 215. Referring to FIGS. These rails 215 are spaced apart from angle plates 201 and 202 by spacers 217. rail 215
and spacer 217 are bolted and joined to angle plates 201 and 202.

The rail 215 has a beveled end that closely engages a beveled idler roller 219 (FIG. 14). Roller 219 is bolted to structural assembly 221. Structural assembly 221 further includes a welded box structure 223 for added rigidity. Structural assembly 221 is bolted to the superstructure described above with reference to FIG.

14 and 15, the carriage apparatus 20 is supported by a hydraulic cylinder 225 for vertical oscillation. The piston within this hydraulic cylinder 225 is attached to the top plate of the carriage device 20 by a bracket 227. Hydraulic cylinder 225 is controlled by servo valve 229 via manifold block 231.

The hydraulic cylinder 225 itself has an arm 23 bolted to the structural assembly 221.
3 (Fig. 14). Servo valve 229 is under the control of a computer (not shown) which directs the desired relative movement between the strand and the mold to properly solidify the cast strand. In particular, the mold vibrations produce an effect on the rod or strand 12 that is identical to the pattern of forward and backward strokes of the rod or strand itself.

Figures 7-9 are presented to illustrate the effect of mold vibration on cast layer formation and to explain the "forward" and "backward" strokes. FIG. 7 shows mold assembly 18 at its lowest point within melt 14. FIG. At this point, the mold assembly has begun to accelerate upwards as indicated by small arrow 41. At this time, the rate of rise of the strand is greater than the rate of rise or advance of the mold. Note that the coagulated skin 12a of the strand 12 is extremely thin. FIG. 8 shows mold assembly 18 approximately halfway through its travel up and down the melt. At this time,
The mold assembly reaches an intermediate point and its rate of rise is greater than the rate of rise of the strands. This is due to the upward acceleration of the mold assembly, which in many applications is about 2g. It is again emphasized that the speed of the strands is constant and only the speed of the mold assembly varies. In FIG. 8, the solidification front 29 has moved closer to the top of the melt. The skin 12a is thicker than the skin shown in FIG.

Figure 9 shows the mold at the top of its travel path.
At this point in FIG. 9, the mold velocity in the upward or forward direction is zero and is just beginning to return toward the position shown in FIG. At this location the coagulation skin 12a is thickest. Advancement and retraction speeds can be adjusted separately by computer to obtain optimal surface quality and material structure.
Considering Figures 7 to 9, the "forward process" is
It is clear that movement of the mold assembly away from the melt is meant, while by "backward stroke" is meant movement of the mold assembly into the melt.

4 and 5 illustrate a preferred embodiment of the mold assembly 18 and how it is continuously supplied with coolant.
Coolant, preferably water, enters manifold 54 at inlet 100, travels down annular passage 101 in manifold extension assembly 102, and remains in cooling body 103 to cool mold 104. The coolant is returned via annular passage 105;
It flows out from the outlet 106. Passages 101 and 105
is an annular space formed by three concentric tubes 107, 108 and 109, each made of steel. External tube 107 is flanged to manifold 54. The two internal tubes 108 and 109 are connected to the manifold 54
Slide into O-ring gland seal 110 inside. This device compensates for dimensional changes caused by thermal gradients.

Manifold extension assembly 102
The concentric tube structure for allows for high coolant flow rates while minimizing the cross-sectional area of the assembly that must vibrate within the furnace melt. Minimizing cross-sectional area is important to keep hydrodynamic loads on the vibratory mold assembly low.

Referring to the detailed view of FIG. 5, the tubular die 112 is surrounded by a cooling body 103.
Die 112 has a lower end portion 112a that projects beyond the lower surface 103a of the cooling body. The die section 112a and at least a portion of the cooling body are immersed in the melt 14 during casting. The static pressure of the copper forces the liquid melt into the die towards the cooling body. At the start, a length of straight rod is inserted into the die through a graphite plug and positioned with its lower end (usually holding a bolt) somewhat above the normal solidification or casting region 114. . The immersion depth is the casting zone 11 where rapid heat transfer from the melt to the cooling body solidifies the melt to form a solid casting without passing through the starter rod.
The liquid melt is selected to reach 4. Because the melt adjacent to the die cools more quickly than the melt located in the center, an annular "skin" forms around the liquid core. The liquid-solid interface is a solidification front 114a that crosses the casting region 114.
stipulates. Preferably, the top of the solidification front 114a is always located below the surface of the melt 14. Since solidification begins within the area of die 112 lined by insulating pushing 118,
The location of the coagulation front is well defined. A basic feature of the invention is that the casting zone is characterized by a high cooling rate and a steep vertical temperature gradient at its lower end, so that the casting zone extends over a relatively short length of the die 112. It is. These features are the result of the melt starting to solidify in the area of the die lined by the insulation member or pushing 118.

Although the invention is described with respect to the preferred upward casting direction, it should be noted that the invention can also be used in horizontal casting and down casting. Thus, the term "below" means closer to the melt and the term "above" means farther from the melt. In drop casting, for example, the "lower" end of the mold assembly is actually over the "upper" end.

Die 112 is formed of a refractory material that does not substantially react with metal and other vapors present in the casting environment, particularly at temperatures above 2000°. Graphite is the commonly used die material, but good results have also been obtained using boron nitride. More specifically, it is manufactured by Poco Graphite Company under the trade name DFP.
It has been found that graphite sold with a rating of -3 exhibits uniquely good thermal properties and durability. In addition to the selection of the material for the die, it is preferable to degas the die in a vacuum furnace before installation to remove volatile matter that reacts with the melt and causes trouble at start-up or surface defects during casting. This vacuum environment also prevents the graphite from being oxidized when it is degassed at high degassing temperatures (eg, 750ⓓ) for 90 minutes in a coarse pump vacuum.
It will be appreciated by those skilled in the art that other components of the mold assembly should also be free of volatiles, especially water, before use. Components formed from Fiberfrax refractory material (a trade name for Carborundum Co.'s alumina-silica refractory paper material) have approx.
Pretreated by heating to 1500 °C, and also other components made of e.g. silica.
Usually heat treated to 350〓~400〓.

Die 112 is generally tubular in construction and has a uniform inner diameter and a substantially uniform wall thickness.
The inner surface of the die must be extremely smooth to provide low frictional resistance and reduce wear as the casting moves axially or longitudinally within the die. Similarly smooth surrounding inner surface 1 of cooling body 103
03b. Surface 103b clamps down on the die as it expands radially due to heating by the melt or casting, and the resulting compression transfers heat from the die to the cooling body very efficiently.

The fit between the die and the cooling body is important. This is because a poor fit, or gap, severely limits heat transfer from the die to the heat sink. A tight fit is
It is also important to prevent longitudinal movement of the die relative to the heat sink due to friction or "drag" created between the casting and the die as the casting is drawn through the die. On the other hand, the die should be able to be quickly and easily removed from the cooling body when it is damaged or worn out. All of these objectives are accomplished by finishing the mating surfaces of the die and heat sink to close tolerances that allow for a "slip fit," or axial sliding insertion and removal of the die.

The dimensions forming the die and mating surface 103b are selected such that thermal expansion of the die during casting creates a tight fit. The material of the die usually has a coefficient of thermal expansion of the cooling body (10 x 10 ^-6 inch/
inch/〓) much lower coefficient of thermal expansion (5
×10 ⁻⁶ in/in/〓), but the die is much hotter than the heat sink, and the temperature difference more than compensates for the difference in coefficient of thermal expansion. The average temperature of the entire thickness of the die in the casting area is 2000 〓
It is believed to be about 1000〓 for . The temperature of a cooling body is the temperature of the coolant that circulates through it, usually
It is around 80゜~100〓.

Mechanical restraints are used to hold the die in the cooling body during low speed operation or start-up before the die undergoes thermal expansion due to the melt. Straight line restraining members, such as screws or retaining plates, have been found to be impractical because they are cooled by a cooling body and condense and collect metal vapors. That is, this metal deposit leads to surface defects during casting and/or
or welding the restraining member in place, which significantly impedes die exchange. Zinc vapors present in brass castings are particularly troublesome. An acceptable solution is to form small upsets or irregularities 103c on the inner surface 103b of the cooling body, for example by raising the burr with a nail set. formed on the outer surface of the die that engages the lower surface 103a of the heat sink (more specifically an "outer" insulating bushing or ring 118 disposed in a counterbore 103d formed in the lower end of the heat sink) The small stepped step 116 indexes the die for setup and provides an additional upward restraint against irregular large forces that may occur, for example, during start-up. It should be noted that the monolithic construction of the die eliminates the need for joints, especially joints between dissimilar materials. This joint can collect condensed vapors or facilitate their passage to other surfaces. Monolithic dies are easier to replace and lock down than multisection dies.

Another device for establishing a proper tight fitting relationship between the die and the heat sink is a conventional press fit or thermal fit. In the press fit, a molybdenum sulfide lubricant is used on the outer surface to reduce the possibility of die cracking during press fitting. This lubricant also fills in any scratches from die machining. In a thermal fit, a cooling body is expanded by heating, a die is inserted, and a tight fitting is established when the assembly cools.
However, both press fits and thermal fits require removal of the entire mold assembly 18 from the cooling water manifold to perform die changes. This is clearly more time consuming, inconvenient, and costly than a slipfit.

A preferred form of the invention uses a monolithic die with a uniform bore diameter, but with a tapered or stepped interior surface that narrows upwardly or where two or more parts are adjacent at the ends. It is also possible to use a multi-section die configured in this manner. An upwardly narrowing is desirable to compensate for shrinkage of the casting as it cools. Intimate contact of the casting along the length of the die increases cooling efficiency of the mold assembly. Increased cooling efficiency is important because it helps prevent the creation of center voids due to unfed shrinkage of the molten center of the casting.

To minimize cost, a reverse taper is cut on the outer surface of the die or on the inner surface 103b of the cooling body than on the inner surface. Thermal expansion of the die within the coolant bore during casting creates a desired upwardly narrowing taper on the highly smooth inner surface of the die. Multi-section dies can have the same bore diameter or different bore diameters with upwardly tapering steps. To avoid troublesome metal build-up between die sections, joints between sections should be made only in the upper part of the casting area. The upper section above the casting area can be press fit as the lower section is extremely susceptible to damage and requires replacement.

A monolithic die formed of Poco-type graphite suitable for casting 3/4 inch rods, including but not limited to, is approximately 101/2 inches long and approximately 1/8 inch long. Has a uniform wall thickness of ~1/5 inch. Generally, wall thickness varies with the diameter of the casting. Projecting die portion 112a typically has a length of 2 inches.

Cooling body 103 has a generally cylindrical outer shape and has a longitudinally extending central opening defined by an inner surface 103b. The inside of the cooling body contains a cooling liquid,
In particular, it has a passage designated by 120 for circulating water to the cooling body. Series of coolant inlet openings 1
20a and a coolant outlet opening 120b are formed at the upper end of the heat sink. As best seen in FIG. 6, these openings are arranged in concentric circles with openings sufficient to provide a high flow rate, typically one gallon per pound of casting per minute.
A pair of O-rings 122 and 123 are preferably formed from a durable fluoro-elastomer and are in fluid communication with the inlet and outlet openings to seal the manifold extension assembly 102 (see FIG. 5). do. Mounting flange 1 on the cooling body
24 has an opening 124a that receives a bolt (not shown) by which the mold assembly is secured to the manifold extension assembly. This flange is
It also has holes (not shown) to vent gas from the annular space between the cooling body and the insulating cap (see FIG. 4) to the atmosphere through tubes (not shown) in the manifold 54.

The cooling body has four main components. That is, the inner body 126, the outer body 128,
These include jacket closure ring 130 and mounting flange 124. The internal body is formed from a hard, wear-resistant alloy that exhibits excellent heat conduction properties and good dimensional stability. Age hardened copper, such as the CDA182 alloy, is preferred. The outer body 128, the closure ring 130 and the mounting flange 124 are preferably formed from stainless steel, and in particular the ring 130 and flange 124 are formed from stainless steel having a freely processable 30 mm diameter.
3 stainless steel, external body 128 is 304
Stainless steel is preferred. Stainless steel exhibits satisfactory resistance to mechanical abuse, has similar thermal expansion properties to chromium copper, and holds up well in casting environments. The use of stainless steel eliminates the need for a significant number of age-hardened copper components.
This makes the production of the cooling body more practical.

The internal body is constructed from a single cylindrical billet of high quality (crack-free) chrome copper. As well as advantages in cost and functional durability, composite heat sinks are recommended because of the difficulty in manufacturing good quality billets of chromium copper that are large enough to form the entire heat sink. Vertical hole 1
20c is deeply bored into the inner body and is connected to the inlet 12.
Define 0a. Hole 120c extends at least to the casting area, and preferably slightly beyond the casting area (see FIG. 5). The horizontal hole 120d is
It is bored at the bottom of the vertical hole 120c. The upper and lower ends of the inner body are 126a and 126b.
are threaded to receive a mounting flange 124 and a closure ring 130, respectively, for increased mechanical strength. The closure ring has an upwardly facing inner recess 130a that abuts an engagement step on the inner body to improve brazejoint efficiency and prevent the flow of cooling water to the joint. and align the ring with the inner body. The outer recess 130b facing upward is in a fluid-tight state.
relationship) and sits at the lower end of the outer body 128.

The joints are also brazed with copper/gold because the threaded connections at 126b will leak if not well sealed and are required to withstand re-solutionizing and aging of the softened coolant bore. . Although the copper/gold brazing process is a conventional technique, the following technique produces a reliable bond that will withstand a foundry environment. That is, first the contact surfaces of the closure ring and the inner body are copper plated. The plating is preferably 0.001 to 0.002 inches thick and should include threads, recesses 130a and grooves 130c. The brazing material may e.g.
Group 1 in 6c and on top of closure ring 130
It is applied by wrapping the wire material around the inner body in 30c. Diameter is 1/16
Inch, 2 turns of wire made of 60% copper and 40% gold with a clearance of 126c, Group 13
It is recommended to use 3 volumes during 0c. A brazing paste of the same alloy is then applied onto the contact surfaces. The closure ring is tightly screwed onto the inner body, and the assembly is placed in the furnace with the brazed end down, preferably using a fiber sold by Carborundum under the trade name Fiberflux. The product is located on a supported sheet of alumina-silica fireproof paper material. The brazing temperature is measured by a thermocouple located at the bottom of one vertical hole 120c. The furnace is used for short periods of time (e.g.
Braze the assembly (for 10 minutes) at a temperature slightly below the melting point of the alloy (e.g. 1760〓~1790〓)
Make it. The furnace atmosphere is protected, for example by inert gas or vacuum, to prevent oxidation. The assembly is then heated to the liquefaction temperature of the brazing alloy (1860〓~1900〓)
and immediately cooled again to room temperature under a protective atmosphere. Solution treatment of chromium copper is carried out at 1710〓~1750℃ for 15 minutes in a protective atmosphere in a separate second step.
This is best done by heating the part to 100% and then liquid cooling.

Once the closure ring has been joined to the inner body, the remaining assembly of the cooling body is assembled with parts 400〓
After preheating, type 304 to type 303 stainless steel is TIGed using a type 308 welding rod.
Including welding. The outer body 128, typically of cylindrical construction, is welded to the closure ring at 134.
The upper end of the external body has a water outlet opening 120b.
It has an inner recess 128a that aligns with the mounting flange 124 just outside the. Welds 136 hold these parts securely. The closure ring and mounting flange are spaced from the inner body to the outer body and define an annular water circulation passageway 120e extending between the transverse hole 120d and the outlet opening 120b. A helical spacer 138 is retained within the passageway 120e and provides a swirling flow of water that promotes more uniform and effective heat transfer to the water. spacer 1
Preferably, 38 is formed by 1/4 inch copper rod. The spacer coil is filed flat at point 138a, thereby providing clearance for a retaining clip 140 secured to the inner body. Both aging (quenching) treatment of chromium copper and stress relief of welded stainless steel are carried out in a protective atmosphere for at least 2 hours.
It is carried out at 900°. The cooling body is then machined and leak tested.

According to the drawing, the cooling water is supplied through the inlet 120a and the hole 12.
0c and 120d, and through a helical channel defined by passageway 120e and spacer 138 to outlet 120b. Cooling water usually has a concentration of 80~90〓 at the inlet, and about 10〓 while circulating through the cooling body.
Temperature rises ~20°. Typically, the flow rate of cooling water is about 1 gallon per minute per pound of strand solidified in the casting area. Normal flow rate is 25
gallons per minute. The suitable water temperature is limited at its lower end by water vapor condensation. On humid days, condensation can occur below 70〓, but usually does not exceed 80〓. Water temperatures above 120° are usually undesirable. Reverse the inlet hole and outlet hole, and drain water into hole 120b.
Even if it is inserted into the outer ring of the hole 120a and discharged from the inner ring of the hole 120a, there will be no significant reduction in the cooling performance of the cooling body. However, the spacing between the die and the internal set of holes is a factor that affects the efficiency of heat transfer from the casting to the water. For 3/4 inch strands 12, the spacing is typically about 5/8 inch.
This allows one inch diameter strands to be cast and the inner body re-drilled to accept the outer insulation 118 of the preferred dimensions. In general, the mold assemblies described above provide higher cooling rates than conventional water jacket coolers for chilled mold casting in closed systems.

Another important feature of the invention is that it allows the die to be dimensionally stable in the casting zone and prevents excessive outward expansion of the die below the casting zone (bell mounting) leading to stoppages, poor starting or surface defects. ) is an outer insulating bushing 118 that prevents Bushing 118 is also important when creating a steep axial die temperature gradient just below the casting zone. For example, if there is no bushing 118,
A sharp temperature gradient exists at the entrance of the die to the cooling body, resulting in the lower portion 112a of the die forming a bellmouth casting skin. The enlarged part is not drawn past the casting area into the cooling body. It wedges in during the continuation of casting and can break off from the casting and remain in place. This wedged area results in poor surface quality and stoppage of the strand. Bushing 118 prevents this problem by mechanically restraining outward expansion of the die immediately below casting region 114. This bushing effectively insulates the die from the cooling body and
A gentle thermal gradient is created in the die over a region extending from 03a to slightly below the lower end of casting region 114.

Bushing 118 is formed from a refractory material having a relatively low coefficient of thermal expansion, relatively low porosity, and good thermal shock resistance. The low coefficient of thermal expansion limits the radially outward pressure exerted by the bushings on the heat sink and suppresses the graphite to maintain a substantially uniform die inside diameter with the heat sink. The low coefficient of thermal expansion allows bushing 118 to be easily removed from the heat sink by uniformly heating the assembly to 250°. The preferred material for bushing 118 is machineable cast silica glass (SiO ₂ ).
It is.

The bushing 118 is the lower surface 1 of the cooler body.
It extends vertically from a lower end surface 118a at the same height as 03a to an upper end surface 118b slightly above the lower end of the casting area. In manufacturing 3/4 inch brass rods, bushings with a wall thickness of about 1/4 inch and a length of 1 3/8 inch give satisfactory results.

In implementation, the metal vapor is inside the insulating bushing 1
18 and the coolant counterbore 103d, condensing and bonding the ring to the coolant, making it difficult to remove. A thin steel foil shim 142 placed between the ring and the counterbore solves this problem. The bushings and shims are held in the counterbore by a special thermal fit, which allows easy assembly and removal when the bushings and cooling body are heated to 400°C.

Figures 11 and 12 illustrate other devices for allowing casting to occur in a dimensionally uniform portion of the die and for controlling expansion of the die below the casting area. FIG. 11 shows the protruding lower end 11
Die 112' is shown identical to die 112 except that 2a has an upwardly expanding taper formed on its inner surface. The degree of taper is selected to produce a generally uniform diameter bore when the die section expands in the melt. However, although this solution is difficult to fabricate, it nevertheless uses bushing 118 (shown in phantom) and die 112' in practice to achieve the high manufacturing speed and good casting quality characteristics of the present invention. It is necessary to do so.

FIG. 12 shows an "inner" insulation 114 sliding into a die 112'' which is identical to die 112 except that it terminates at the same height as the coolant surface 103a.
It shows. Inner insulation 144 is formed from a refractory material that does not react with molten metal and has a relatively low coefficient of thermal expansion so that it does not deform the cooling body. The lower end of the insulator 144 extends slightly below the lower end of the die 112'' and the cooling body;
6 and has an enlarged outer diameter to form a step 144' similar in function to 6. This upper end is located near the lower end of the casting area, usually at bushing 118.
1/2 inch below the top edge of the If the top ends extend too high relative to the outer insulation, the strands will be cast against the insulation, leaving indentations in the strands. The bore diameter of the inner insulation is also important, especially during starting, stopping, and deceleration. This is because the melt is the inner insulator 14.
This is because it begins to coagulate on top of 4. The inner surface of the insulator 144 must be smooth and widely tapered upward to prevent stalling. Die 112'
With respect to the outer insulation or bushing 118,
Inner insulation 144 to reduce the above-mentioned difficulties
used with

Referring again to FIG. 4, ceramic cap 146 surrounds and thermally insulates heat sink 103 and manifold extension assembly 102 from the metal melt so that the heat sink accomplishes its function of cooling the mold. can occur, resulting in solidification of the rod. Cap 146 is formed from a suitable refractory material such as cast silica. hat 14
6 is connected to the manifold 54 by the spring 149.
ring 148 spring biased against
It is attached to the manifold 54 by. This attachment draws cap 146 tightly against cooling body 103 to account for dimensional changes due to differential thermal expansion. Spring 149 is preloaded to produce a total force greater than the highest G load experienced during vibration, thereby causing cap 146
A tight seal is maintained between the cooling body 103 and the cooling body 103. The cap allows the mold assembly to be immersed into the melt to a preselected depth. Immersion to a level below the casting area is functional, but
The extremely high production rate characteristics are in part a result of the relatively deep immersion, eg at least to the level of the casting zone. One advantage of this deep immersion is that it facilitates feeding the melt into the liquid core of the casting in the casting zone.

A vapor shield 150 and gasket 154 (also shown in FIG. 5) are placed in the gap between the cap and the cooling body next to the die to prevent melt and steam from entering the gap and to further heat the cooling body. Insulate properly. The gasket is preferably an annular three or four layer or "doughnut" of the fiber flux refractory fibrous material described above, while the vapor shield is a "doughnut" of molybdenum foil inserted between the gaskets 151. ” is preferable. Shield 150 and gasket 151 extend from die extension 112a to the outer diameter of the heat sink. The total thickness of these layers is sufficient to intimately engage the heat sink surface 103a and the end surface of the cap 146, and is typically 1/4 inch.

In a typical operating cycle, the casting furnace 16
is filled with molten alloy. A rigid stainless steel rod is used to start the casting. A steel bolt is screwed into the lower end of the rod. The rod has the dimensions of the strand to be cast, for example 3/4 inch in diameter, so that the rod can be fed down through the mold assembly and engageable with the drawer 22.

Whenever the mold assembly is inserted into the melt, a cone of material, preferably solid graphite, that is non-contaminating to the melt being cast covers the die portion 112a (or a refractory die extension, such as inner insulation 144). cover. An additional alloy cone 48 of a material that is non-contaminating to the melt, typically copper, covers the lower end of cap 146. These cones penetrate the dross on the surface of the cover and melt, reducing the amount of foreign particles trapped under the cooler and in the die. Melt is cone 4
8 and the starter rod bolt forces a small graphite cone into the die, which floats to the side. One advantage of the preferred form of the invention that uses a protruding die portion 112a is that it supports and keeps the small graphite cone in place during insertion into the melt. To function properly, the surface of the large cone 48 should form an angle of 45 degrees or less with respect to the vertical.

After the graphite cone is replaced, the bolt extends into the melt and the melt solidifies on the bolt. When starting and the strand is the drive wheel 4
4, the cast rod is sheared under the steel bolt and the strands are mechanically directed onto the booms 24, 24'. Short length castings and steel bolts are removed before replacing the starter rod in the storage rack for reuse. Other shapes of starter rods include
Includes a short length of rigid stainless steel rod attached to a flexible cable that is fed directly onto the boom 24 due to its flexibility. The drawer is then increased to speed to begin casting. During shifts or during temporary interruptions in operation, such as for coiler replacement, the strands are stopped and clamped. Casting is resumed by simply unclamping and increasing to full speed.

As the strand 12 is withdrawn, the forward stroke pulls the solidified casting formed in the casting or solidification region upwardly, exposing the melt to the cooled die and depositing it on this newly exposed die surface. A skin is quickly formed. In steady-state operation, the rod is pulled at a constant speed ranging from 200 to 400 inches/minute. At the same time, the entire mold assembly, including die 112, is vibrated vertically with an acceleration of about 1 g, reaching a maximum velocity of about 4 inches/second in each direction. This vibration strengthens the new skin and allows it to adhere to the previously formed casting. High cooling rate of cooling body and outer insulation 118
Solidification occurs very quickly over the relatively short length of the die due to the steep temperature gradient created by the die.
As already mentioned, typical melting temperatures for oxygen-free copper and copper alloys are between 1900 and 2300.
When carrying out the present invention, a heat insulating body (butting 1
18) insulates the melt from the cooling body and maintains the melt in a liquid state inside the die below the casting area. Near the upper end of the insulation, the melt temperature drops rapidly and solidification begins. When casting 3/4 inch brass rods at 100 ipm or higher, the casting area extends 1 to 1 1/2 inches vertically. At the top of the casting area the strand is solid. The estimated average temperature of brass castings in the solidification region is 1650〓~1750〓. The typical temperature of the brass casting as it exits the mold assembly is 1500°C. There is a clearance around the strands at the upper end of the mold assembly to allow an oxygen or water saturated atmosphere to burn off the zinc vapors before they condense and flow down to the casting area. The strands produced in this way are characterized by a fine grain size and dendrite structure, good tensile strength and good ductility.

A simple and low cost vibratory mold assembly and drawing method using the mold assembly has been described that allows high quality metal (particularly brass) strands to be produced continuously at extremely high speeds. In particular, the mold assembly and drawing method of the present invention can be applied to
It provides an advanced solution to many serious problems associated with casting atmospheres, such as foreign particles present in the casting area, differences in the coefficients of thermal expansion of the materials forming the mold assembly.

The invention is further illustrated by the following non-limiting examples.

Strand 12 was continuously cast from a melt of free machining brass, CDA360, using the apparatus shown in FIG. 4400 pounds of molten alloy was charged into furnace 16 and maintained in a molten state. Alloy CDA36
The composition of 0 is as follows: Lead 2.5-3.7 Copper 60.0-63.0 Iron 0-0.35 Impurities 0-0.5 Zinc Balance. Die 1 a pipe with a thread at its end
12 into the melt and then withdrawing the pipe in a manner known in the art, the solidified strand 12 is passed by rollers 44 at a speed of 200 inches/minute. It gets pulled out. At the beginning of continuous drawing of strand 12, the body 18 of the vibrating mold was immersed in the melt to a depth of about 5 inches. The immersion depth of the body 18 during casting varied from about 7 inches to about 3 inches. The temperature of the melt was maintained at 1850° during mold vibration, and molten alloy was supplied to the furnace 16 as needed during casting to maintain the immersion depth of the body 18. The diameter of the die 15 was 0.75 inch, resulting in a strand 12 having a diameter of approximately 0.75 inch. Advance and retract mold speeds during vibration reached a maximum value of 4 inches/second with a mold acceleration of 1 g. The distance the mold traveled between the highest and lowest point in the melt was approximately 1.75 inches. The temperature of strand 12 exiting die 112 was approximately 1500°C.

After casting, the bar was successfully hot processed. The casting grain size was columnar and 1 mm. The fabricated structure was finely recrystallized (0.025-0.050 mm) throughout the section.

Although this invention has been described in terms of its preferred embodiments, those skilled in the art will recognize that it includes various improvements and modifications. For example, die 11
Although die 112 has been described as extending the entire length of the cooling body, in many applications die 112 may extend only a short distance above the casting area. The cooling body can also take on a variety of other configurations and dimensions. These improvements and modifications are intended to be within the scope of the claims.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view of a strand production facility employing a vibratory mold assembly and method embodying the present invention; FIG. 2 is a partially sectional side view showing the vibratory mold and support structure together with a furnace for holding the melt; 3 is a perspective view of a structure for supporting a vibratory mold; FIG. 4 is an isolated cross-sectional view of a support manifold extension assembly and mold of the structure of FIG. 2;
Figure 5 is an enlarged view of the cooling body and the mold shown in Figure 4, Figure 6 is a plan view of the cooling body shown in Figure 5, and Figures 7 to 9.
10 is a schematic vertical sectional view of the casting furnace shown in FIG. 1 in the lower and upper positions relative to the mold assembly; FIG. Figures 1 and 12 are schematic cross-sectional views showing another device for controlling the expansion of the die below the casting region;
13 is a perspective view of a carriage supporting the mold for vibration; FIG. 14 is an isolated plan view showing the carriage device of the structure of FIG. 2 for supporting and moving the mold; and FIG. FIG. 3 is a partially cutaway front view of the carriage device. 12...Metal strand, 12a...Coagulation skin,
14...Melt, 15...Die, 16...Casting furnace, 16
a... Pour spout, 18... Mold assembly, 20
...carriage device, 22...puller, 26...coiler device, 28...duct, 29...coagulation front, 30...ladle, 32...cradle, 34...casting platform, 36...casting cup, 38...lifting dolly device, 38a... Load cell, 44... Pinch roll, 46... Hydraulic motor, 48... Protective cone, 1
03... Cooling body, 104... Mold, 112, 112',
112″...Die, 114...Casting area, 114a...
Solidification front (front), 118, 144...Insulator.

Claims (1)

[Claims] 1. A casting method for continuously casting metal strands from a metal melt, in which a die having a first end is provided with a die having a first end to allow parts of the die to be cooled. a cooling body having a first end surrounding a portion of the die; and a cooling body between the portion of the die and the cooling body for insulating the portion of the die from cooling of the cooling body. an insulating member located at the first end of the cooling body and extending a first length between the die and the cooling body; immersing the end in the melt for a length greater than the first length to form a solidification front within the die below the level of the melt as the melt is drawn through the cooling body; Draw molten metal from the melt through the die while cooling the die through the cooling body, and upon cooling form the molten metal into strands within a portion of the die below the level of the melt and above the insulation member. A casting method characterized in that, upon complete solidification, the solidified strand is withdrawn from the melt at a constant speed; and the die is oscillated in a direction parallel to the direction of movement of the strand. 2. Claim 1, wherein the first end of the die extends beyond the first end of the cooling body.
The method described in section. 3. The cooling liquid is applied to the above in order to initiate the solidification of the melt into strands in the part of the die lined by the insulating member and to fully solidify the melt into strands in the part of the die above the insulating member. 2. The method of claim 1, wherein the cooling body is circulated to a point immediately above the top of the insulation member. 4. The method of claim 3, wherein the portion of the cooling body immersed in the melt is protected from the heat of the melt by an insulating material forming an insulating barrier between the melt and the cooling body. 5. The method of claim 1, wherein said strand is drawn from said die at a drawing rate of 200 to 400 inches per minute. 6. The method of claim 5, wherein the die is vibrated with an acceleration of about 1 g in each direction and reaches a maximum speed of about 4 inches per second. 7. The method according to claim 6, wherein the vibration frequency is in the range of 12 to 150 cycles/min. 8. In a casting apparatus for continuously casting metal strands from a metal melt, a generally tubular die having a first end in fluid communication with the melt; allowing parts of said die to be cooled. a cooling body having a first end surrounding a portion of the die for the purpose of insulating the portion of the die from cooling of the cooling body; a heat insulating member located at the first end of the cooling body between and extending a first length between the die and the cooling body;
The first end of the cooling body is immersed in the melt for a length greater than the first length so that the die is below the level of the melt as the melt is drawn through the cooling body. means for forming a solidification front therein; for drawing molten metal from the melt through the die while cooling the die through the cooling body, the cooling being below the level of the melt and above the insulation member; means for completely solidifying the molten metal into a strand within a portion of the die and withdrawing the solidified strand from the melt at a constant rate; and means for vibrating the casting apparatus. 9. Cooling the cooling liquid to initiate solidification of the melt into strands in the part of the die lined by the insulation and to fully solidify the melt into strands in the part of the die above the insulation. 9. The device of claim 8, which circulates through the body to a point just above the top of the insulation member. 10. The apparatus of claim 8, wherein the melt height is adjusted continuously in relation to the cooling body. 11. Apparatus according to claim 10, wherein the height of the melt is adjusted by an elevator that raises in response to a signal regarding the weight of the melt.