JPH04220141A - Device and method for manufacturing hollow billet - Google Patents

Abstract

PURPOSE:To continuously and smoothly manufacture the hollow billet by drilling the cooling tube passage opening to one end side at the core, and inserting the coolant supplying tube which extends from one end of the cooling tube passage to the other end part and opens at the other end part. CONSTITUTION:The tubular mold 1 is cooled by supplying the coolant from the mold coolant supplying tube 7, the core 2 is arranged by the same axis in the casting mold 1. The molten metal C is supplied from one end side of the tubular space formed between the casting mold 1 and the core 2, and the hollow billet is manufactured by cooling and solidifying it in this space. Then, the cooling tube passage 21 which is entered from one end and opens to the same one end only is set in the core 2. Also, the core coolant supplying tube 23 which extends from the one end of the cooling tube passage 21 to the other end part and opens at this other end part is inserted. Therefore, the hollow billet without generating a segregating layer can be obtained.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to the manufacture of hollow billets, which are produced by continuously casting hollow billets from molten metal. The present invention relates to an apparatus and method for manufacturing hollow billets that are optimal for manufacturing hollow copper billets that serve as coating materials for superconducting wires.

0002

[Prior Art] In order to manufacture wire rods made of such superconducting materials, since superconducting materials themselves generally have poor ductility, it is necessary to first fill a cylindrical member made of a highly ductile material such as copper with the superconducting material. A method is adopted in which the entire cylindrical member is stretched to obtain a superconducting wire coated with a copper covering material.

[0003] Here, in order to create the copper cylindrical member, for example, a method can be considered that first a copper cylindrical member is formed and then a through hole is drilled along the axis of this cylindrical member. .

[0004] However, since copper generally does not have very good machinability when cutting, etc., this method requires a great deal of effort to drill through holes, and above all, the yield rate decreases because the through holes have to be removed. It has the disadvantage of causing a decrease in

[0005] Therefore, a method has been adopted in which copper is previously formed into a cylindrical hollow billet by casting or the like, and then the inner and outer peripheral surfaces of this hollow billet are processed to obtain a cylindrical member made of copper.

FIG. 2 shows a hollow billet manufacturing apparatus for manufacturing such a hollow billet from molten copper. It is generally composed of a multistage cylindrical core 2 inserted along the central axis of the mold 1.

The inner peripheral surface of the mold 1 is lined with an inner wall 4 made of graphite or the like with a refractory heat insulating material 3 in between. Moreover, the inside of the body circumference of the mold 1 forms a hollow part 5, and this hollow part 5
is communicated with the open end 6 below the inner wall 4 of the inner peripheral surface of the mold 1 through the outer periphery of the refractory heat insulating material 3, and a mold coolant supply pipe 7 is connected from the outer periphery of the mold 1. Further, a lid part 8 is provided at the upper end of the mold 1 so as to cover the upper end opening, and a supply port 9 for supplying molten copper is opened in the lid part 8.

The core 2 is made of graphite or the like like the inner wall 4, and is attached to the lid part 8 so as to hang down and be coaxial with the central axis of the mold 1. The lower part of the core 2 that is inserted into the mold 1 is tapered so that the diameter decreases slightly as it goes downward, and the upper end of the hollow part of the core 2 is connected to the upper part of the lid part 8. It extends to a cavity 10 provided in the cavity 10 , and communicates with a core coolant supply pipe 11 connected to this cavity 10 to form a cooling pipeline 12 for the core 2 .

Furthermore, a cylindrical member 13 is loosely inserted into the cooling pipe 12 through the core 2 and coaxially with the central axis, and the upper end of the cylindrical member 13 is connected to the canopy of the cavity 10. and its lower end is connected to the cooling pipe line 12.
It is shaped like a truncated cone that expands in diameter below the lower end opening.

In the hollow billet manufacturing apparatus having such a structure, the mold coolant supply pipe 7 and the core coolant supply pipe 11
A coolant such as cooling water is supplied from the mold 1 and the molten copper C is supplied from the supply port 9 to the cylindrical space formed between the mold 1 and the core 2. The molten copper C supplied to this space comes into contact with the inner wall 4 of the mold 1 and the outer peripheral surface of the core 2 cooled by the coolant, and is rapidly cooled and solidified to form a hollow billet.

The thus cast billet is sequentially pulled out from below the space, and is diffused by the mold coolant spouted from the open end 6 at the bottom of the mold 1 and by the cylindrical member 13 whose diameter expands at the lower end opening of the cooling pipe line 12. The core coolant cools the outer diameter surface and the inner diameter surface, respectively. On the other hand, molten copper C is continuously supplied to the space after the billet has been drawn, and is cooled and solidified integrally with the drawn billet, and then drawn.

Hollow billets can be continuously produced by continuously supplying molten copper C and sequentially pulling out the billets that have been cooled, solidified, and formed from below.

[0013] The manufactured hollow billet has relatively rough outer and inner diameter surfaces, so it is used after being finished.

[0014]

[Problems to be Solved by the Invention] In the hollow billet manufacturing apparatus having such a structure, the molten copper supplied into the space is cooled simultaneously from the inner circumferential surface of the mold 1 and the outer circumferential surface of the core 2. As shown in FIG. 2, the solid-liquid interface between the molten copper and the solidified copper has a downwardly convex shape with an inflection point approximately at the center in the radial direction of the thick portion of the hollow billet.

On the other hand, molten copper produced into such hollow billets generally inevitably contains some impurities. These impurities are more easily dissolved in the liquid molten copper before solidification than in the solidified copper, so as shown in Fig. It aggregates on the copper side, particularly near the point of inflection. If hollow billets are manufactured continuously under such conditions, impurities will segregate in the hollow billet to be cast in a series of points of inflection, and a cylindrical shape will be formed in the radial center of the thick part of the billet. A segregation layer P is formed.

[0016] Since the mechanical strength of a hollow billet in which impurities are segregated in the thick wall portion is extremely degraded in the segregation layer P, the inside of the billet is filled with a superconducting material and stretched as described above. At this time, shearing may occur in this segregation layer P, making it impossible to form the wire rod.

On the other hand, in the device configured as described above,
Since the coolant directly supplied from the core coolant supply pipe flows down the cooling pipe line, the area near the upper end of the core is always at a low temperature due to the freshly supplied coolant. The coolant itself is heated while flowing through the pipe to cool the core, and when it is discharged from the lower end of the cooling pipe, it reaches a high temperature, which causes the area near the lower end of the core to be relatively hot. Put it away. As a result, the temperature gradient of the core is low at the top end and high at the bottom end, and the temperature difference therebetween is relatively large.

For this reason, the molten copper supplied to the space is rapidly cooled when it comes into contact with the core, and the viscosity of the molten copper near the upper end of the space may become extremely low, resulting in what is called molten copper. There was also a risk that the continuous production of smooth hollow billets would be hindered due to poor circulation.

[0019]

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and the hollow billet manufacturing apparatus according to claim 1 has a structure in which a hollow billet is coaxially mounted in a cylindrical mold cooled by a coolant. In a hollow billet manufacturing apparatus in which a core is arranged in a hollow billet, molten metal supplied from one end side of a cylindrical space formed between the mold and the core is cooled and solidified in the space, A cooling conduit is bored in the core from the one end side and opens only to the one end, and the cooling conduit is extended from one end to the other end of the cooling conduit and at the other end. It is characterized by having an open coolant supply pipe inserted therethrough.

Further, the method for producing a hollow billet according to claim 2 includes pouring molten metal into a cylindrical space formed by a cylindrical mold cooled by a coolant and a core placed in the mold. In the method for producing a hollow billet, in which the molten metal is cooled and solidified in the space, a cooling pipe is bored from one end side of the core and opens only to the one end, and one end of the cooling pipe is A coolant supply pipe opened to the other end of the cooling pipe is inserted through the coolant supply pipe, and the coolant is supplied to the other end of the cooling pipe through the coolant supply pipe. The core is cooled by flowing the outside of the coolant supply pipe from the other end to the one end.

[0021]

[Operation] In the present invention, the cooling pipe has a structure in which only one end thereof is open, and the coolant for cooling the core is once supplied to the other end of the cooling pipe through the coolant supply pipe. . The coolant passes through the outside of the coolant supply pipe in this cooling pipe and is fed from the other end to the one end. During this time, while cooling the core, the coolant itself is heated and flows from the one end to the other end. It is discharged. As a result, the coolant flowing through the cooling pipe to cool the core is at a low temperature at the other end of the cooling pipe, and is heated to a high temperature as it moves toward one end of the cooling pipe. The temperature gradient is opposite to that in the example.

[0022] Also, a coolant flowing through the coolant supply pipe,
Heat exchange occurs between the coolant that is heated by being fed from the other end of the cooling pipe to the one end through the coolant supply pipe, so the core is cooled through the cooling pipe. Coolant temperature gradients are kept relatively small.

[0023] Because the coolant has such a temperature gradient, the core cooled by the coolant is also at a high temperature at one end where the molten metal is supplied, and the hollow billet that has been solidified and formed is pulled out. The temperature at the other end is low, and the temperature gradient is kept small.

[0024] The molten metal thus supplied is gradually cooled from the outer peripheral surface of the core, while it is cooled from the inner peripheral surface of the mold as usual, so that the molten metal and the solidified metal part are cooled. The cross-sectional shape of the solid-liquid interface with the metal part forms a downwardly convex curve with an eccentric point toward the core. Along with this, the segregation of impurities is also concentrated on the core side in accordance with the position of the eccentric point, and as a result, the segregation layer of the hollow billet that is cast is also formed in a state that is biased toward the inner diameter side.

[0025] Therefore, by removing this segregation layer during finishing of the inner diameter surface after manufacturing the hollow billet, it is possible to obtain a hollow billet without a segregation layer, that is, without the risk of shearing during stretching. becomes.

Furthermore, in the present invention, since the upper end of the core, which the supplied molten metal first comes into contact with, is at a high temperature, the viscosity of the molten metal is not extremely reduced and the water flow is not deteriorated. This makes it possible to perform smooth continuous molding of hollow billets.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view showing an embodiment of the present invention, and the same parts as in FIG. 2 are designated by the same reference numerals to simplify the explanation.

In this embodiment, a cylindrical mold 1 whose inner circumferential surface is lined with an inner wall 4 made of graphite or the like through a refractory heat insulating material 3, and a lid part 8 provided on the upper part of the mold 1, which hangs down A multistage cylindrical core 2 is inserted coaxially into the mold 1.

A cooling pipe passage 21 having a circular cross section is bored through the core 2 along its central axis from the upper end of the core 2 to the vicinity of the lower end. It communicates with a cavity 10 provided at a further upper part of the lid part 8 that supports the lid part 2. Additionally, a coolant discharge pipe 22 is provided in the cavity 10.
is connected.

[0030] In the cooling pipe line 21, the cooling pipe line 2
A coolant supply pipe 23 having an outer diameter smaller than the inner diameter of the cavity 10 is inserted through the canopy of the cavity 10 from the upper end side of the cooling pipe line 21 along the central axis. is extended to near the lower end of the cooling pipe 21 and opened.

[0031] In order to manufacture a hollow billet made of copper, for example, using the hollow billet manufacturing apparatus having such a configuration, a coolant such as water is supplied to the coolant supply pipes 7 and 23, as in the conventional example described above. At the same time, molten copper C is supplied to the space formed between the core 2 and the mold 1 through the supply port 9 of the lid part 8. The supplied molten copper C is cooled and solidified as it descends within the space, and is cast into a hollow shape. By pulling it out from below the space, the molten copper C that is sequentially supplied is continuously It is cooled, solidified, and drawn into the previously cast hollow copper billet. As described above, in this embodiment, a hollow billet can be continuously cast by supplying molten copper C from the supply port 9 and drawing it out below the space.

Here, the coolant supplied from the coolant supply pipe 23 passes through the coolant supply pipe 23 and is once transferred to the cooling pipe line 21.
The coolant supply pipe 2 is fed to the lower end of the cooling pipe 21 in the cooling pipe line 21.
Go up through the outside of 3. While rising through the cooling pipe 21, the coolant cools the core 2 and is heated to a high temperature, and is then discharged from the cavity 10 through the coolant discharge pipe 22. In this way, in this embodiment, the coolant that cools the core 2 is at a low temperature at the lower end of the core 2, is heated as it moves up the cooling pipe 21, and becomes high temperature at the upper end of the core 2. The temperature gradient is opposite to that of the conventional example, and the core 2 also has a similar temperature gradient.

Furthermore, the low-temperature coolant fed to the lower end side of the cooling pipe line 21 through the coolant supply pipe 23 is cooled by rising outside the coolant supply pipe 23 through the coolant supply pipe 23. heated by the agent. On the other hand, the coolant that rises through the cooling pipe line 21 to cool the core 2 and is heated to a high temperature is supplied to the lower end of the cooling pipe line 21 and flows through the coolant supply pipe 23. cooled through. In this way, the low temperature coolant supplied to the cooling pipe line 21 and the core 2
The coolant supply pipe 2
3, the cooling pipe line 2
The temperature gradient of the coolant that raises the core 1 and cools the core 2 becomes small, and accordingly, the temperature gradient of the core 2 is also kept small.

The core 2 that cools the molten copper C supplied in this manner has a temperature gradient that is high at the upper end side where the molten copper C is supplied and low at the lower end side from which the molten copper C is extracted, and this temperature gradient is By keeping it small, molten copper C becomes
The inner wall 4 side of the mold 1 is cooled relatively slowly from the core 2 side. Therefore, the solid-liquid interface between the molten liquid copper and the solidified solid copper has a downwardly convex cross-sectional shape with the inflection point biased toward the core 2 side, as shown in FIG. Along with this, the impurities contained in the molten copper also aggregate intensively on the core 2 side in accordance with the position of the deflection point, so by manufacturing the billet in this state, the segregation of impurities is reduced. The layer P is formed in a cylindrical shape near the inner diameter surface of the hollow billet, as shown in FIG.

As described above, according to this embodiment, since the segregation layer P is formed near the inner diameter surface of the hollow billet, it is possible to easily remove the segregation layer by internal polishing or the like during the above-mentioned finishing process. It is. This makes it possible to obtain a hollow billet that has no segregation layer and therefore does not shear even when stretched, making it ideal as a coating material when filling the inside with superconducting material and forming superconducting wire. It becomes possible to provide

Further, in this embodiment, the upper end of the core 2, which the molten copper C supplied from the supply port 9 comes into contact with, is located at the upper end of the core 2.
The temperature is relatively high due to the temperature gradient described above. Therefore, unlike in the past, the viscosity of the supplied molten metal is not extremely reduced and the flow of the hot water becomes poor, and hollow billets can be continuously manufactured without any problems.

[0037]

As explained above, according to the present invention, the temperature of the core for cooling molten metal is high at one end where the molten metal is supplied, and low at the other end where the solidified hollow billet is extracted. Since the temperature gradient is suppressed to be small, the supplied molten metal is cooled relatively slowly on the inner diameter side than on the outer diameter side.

[0038] As a result, the solid-liquid interface between the molten metal and the solidified metal forms a downwardly convex cross-sectional curve with the point of inflection biased toward the inner diameter side, and impurities contained in the molten metal are also reduced accordingly. It aggregates along the position of the deflection point. In hollow billets manufactured under such conditions, a segregation layer of impurities is formed near the inner diameter surface, so it can be easily removed during finishing of the inner diameter surface, making it possible to create a hollow billet without a segregation layer. Obtainable. Therefore, even when the inside is filled with a superconducting material and then stretched to form a superconducting wire, shearing does not occur in the hollow billet, and in other words, it is possible to provide a hollow billet that is optimal as a coating material for a superconducting wire.

[0039] Furthermore, since the core has the above-mentioned temperature gradient, the flow of the hot water near the upper part of the core where the molten metal is supplied is improved, so that the continuous production of hollow billets can be carried out more smoothly. be able to.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a hollow billet manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a conventional example of a hollow billet manufacturing apparatus according to the present invention.

[Explanation of symbols]

1 Mold 2 Core 3 Fireproof insulation material 4 Inner wall 5 Hollow part 6 Open end 7 Mold coolant supply pipe 8 Lid part 9 Supply port 10 Cavity part 11, 23 Core coolant supply pipe 12, 21 Cooling pipe line 22 Coolant discharge pipe C Molten copper P Segregation layer

Claims (2)

[Claims] Claim 1: A core is arranged coaxially within a cylindrical mold cooled by a coolant, and the core is supplied from one end side of a cylindrical space formed between the mold and the core. In a hollow billet manufacturing apparatus in which molten metal is cooled and solidified in the space, a cooling pipe opening only to the one end is bored in the core, and a cooling pipe is opened from one end of the cooling pipe. An apparatus for manufacturing a hollow billet, characterized in that a coolant supply pipe that extends to the other end of the cooling pipe line and opens at the other end is inserted. 2. Supplying molten metal to a cylindrical space formed by a cylindrical mold cooled by a coolant and a core placed in the mold, and cooling the molten metal in the space. , in a method for manufacturing a hollow billet that is solidified,
A cooling pipe is bored from one end of the core and opens only to the one end, and a coolant supply pipe is inserted from one end of the cooling pipe to the other end of the cooling pipe. Supplying a coolant to the other end of the cooling pipe through the coolant supply pipe, and flowing the outside of the coolant supply pipe in the cooling pipe from the other end to the one end to cool the core. A method for manufacturing a hollow billet, characterized by cooling.