JPH035046A - Graphite mold device for continuously casting metal cast billet - Google Patents

Abstract

PURPOSE:To effectively remove heat, which is held in molten metal or casting metal at near casting billet solidified zone, from a graphite mold by arranging pipe passage passing cooling medium into the graphite mold for continuous casting. CONSTITUTION:Through holes having suitable diameter are bored to the graph ite mold 1 in a casting apparatus A and by passing through metal pipes of copper pipe, etc., to the holes, the pipe passages 11 for cooling medium are formed, and the cooling medium of high pressure water, etc., is passed in the pipe passages 11. It is effective that such pipe passage 11 for cooling medium is arranged at position, where heat load is largest, corresponding to solidified zone 9 in mainly the graphite mold 1 and the stickiness with contacting part with a water cooling copper block 2 caused by developing heat strain, etc., becomes insufficient. By this method, by executing direct cooling with the graph ite mold 1 together with the water cooling copper block 2, the cooling effect can be improved and the productivity of the casting can be drastically improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a graphite mold apparatus suitable for continuous casting of metal ingots, particularly horizontal continuous casting of plate-shaped ingots of copper and copper alloys.

(Prior Art) Conventionally, in order to produce metal ingots, such as plate-shaped ingots of metals such as copper and copper alloys, there has been a horizontal continuous casting graphite mold apparatus as shown in FIG. It is widely used.

That is, FIG. 2 is a side sectional view showing an outline of this type of graphite mold apparatus, in which 1 is a graphite mold, 2 is a water-cooled copper block circumscribing the graphite mold 1, and 3 is a water-cooled copper block 2. This is a steel cover plate to reinforce and protect the cover. The graphite mold 1, the water-cooled copper block 2, and the steel sheathing material 3 are tightly tightened with a plurality of bolts 4a and 4b, and then assembled together with a frame material 12 to form a mold device A,
A graphite mold 1 is connected to a lining 6 of a molten metal holding furnace B via a heat insulating material 5 and a sealing material 7 so as to be maintained horizontally. The graphite mold 1 has a top plate, a bottom plate, and both side plates facing each other at a predetermined interval and is fixed, with one end protruding from the water-cooled copper block 2 to form an inlet for the molten metal 8, and the other end being a casting hole. A hollow body is formed which is open at both ends to form an outlet of the ingot 10, and the diameter of the hollow cross section is formed to have substantially the same shape and dimensions as the cross section of the ingot to be cast. The water-cooled copper block 2 forms a passageway (not shown) for circulating cooling water therein.

Further, 9 is the solidification zone of the ingot.

The arrangement and number of connecting bolts used for joining the graphite mold 1 and the water-cooled copper block vary depending on the dimensions of the mold used.

(Problems to be Solved by the Invention) In the conventional graphite casting apparatus for horizontal continuous casting of metal ingots, as described above, a large number of bolts are used to connect the graphite mold 1.
I am trying to connect the water-cooled copper block 2 with the
Even if the connection is made using a large number of bolts in this way, the adhesion between the graphite mold 1 and the water-cooled copper block 2 cannot necessarily be said to be completely perfect. For example, during casting, strain deformation occurs in the graphite mold 1 due to the difference in thermal expansion with the water-cooled copper block 2, so the adhesion between the two is insufficient, especially near the ingot solidification zone 9 where the heat load is high. It is not rare that this is not ensured, and the only close contact is in the vicinity of the bolt fastening part, with almost all other parts leaving a gap between the two.

Therefore, in order to improve the adhesion of the contact surface between the graphite mold 1 and the water-cooled copper block 2 near the ingot solidification zone 9, an attempt was made to increase the density of bolt installation in this area, but this resulted in the graphite mold 1 As a result of drilling too many bolt holes, cracks may occur in the graphite material and, in some cases, it may become impossible to cast, so there is a limit to the installation density. An unavoidable non-adhesive area always occurs on the contact surface with the copper block 2, and the existence of an air gap due to this inevitably causes a significant decrease in cooling efficiency for the cast metal of the graphite mold 1.

According to the inventor's actual measurements, in the conventionally used graphite molding equipment as described above, for example, the casting width is 1 ann.
When copper or copper alloy is cast at a casting speed of 100 to 200 mm/min with a design cooling capacity of 40 to 60 KCal/min, the presence of an air gap will cause a drop in the temperature just below the surface of the graphite mold in the ingot solidification zone. The temperature actually reaches around 1100℃ or higher,
In an ideal mold device, the temperature is only several tens of degrees lower than the solidification temperature, and the adhesion is almost perfect over the entire contact surface (in a graphite-coated water-cooled vertical continuous casting device) , the graphite surface temperature in the vicinity of the ingot solidification zone is approximately 500°C, so the cooling efficiency is very low. I can see how.

Therefore, in the graphite mold apparatus for horizontal continuous casting having the above-described structure, how is the heat held by the molten metal or cast metal near the ingot solidification zone used to cool the graphite mold 1?
An important issue was how to effectively remove them.

(Means for Solving the Problems) The present invention aims to solve the above-mentioned problems in conventional graphite mold devices for horizontal continuous casting,
Cooling of the cast metal via the graphite mold 1, which was conventionally performed only by the water-cooled copper block 2, can now be performed directly from the graphite mold 1 by providing a conduit through which the cooling medium passes through the graphite mold 1 itself. It is designed to remove heat from the molten metal.

That is, in the present invention, a through hole of an appropriate diameter is bored in the graphite mold 1 in the molding device, a metal pipe such as a steel pipe is passed through the through hole to form a refrigerant conduit, and a cooling medium such as high pressure water is inserted into this conduit. It allows the medium to pass through. However, according to experiments conducted by the inventors, such refrigerant pipes are subject to the highest heat load, mainly in the areas corresponding to the solidification zone of the graphite mold, and the adhesion of the contact area with the water-cooled copper block may be affected due to thermal distortion. It has been found that it is effective to provide it in locations where the

Furthermore, when such a refrigerant pipe is provided in the graphite mold near the solidification zone according to the present invention, premature solidification of the molten metal due to excessive cooling near the molten metal inlet of the graphite mold,
As the viscosity increases, the flow of molten metal into the mold may become insufficient, which may impede smooth casting. It is desirable to replace the protrusion with a refractory heat insulating material to improve heat retention near the end of the graphite mold on the molten metal inlet side.

(Function) Next, an outline of the structure and function of the graphite mold device for continuous casting of metal ingots according to the present invention will be described.

FIG. 1 is a sectional side view of a main part of an apparatus shown for explaining the present invention in detail. Note that the symbols shown in FIG. 1 are the same as those shown in FIG. 2 shown above, except for those specific to the present invention.

As shown in FIG. 1, the basic structure of the molding apparatus of the present invention is the same as that of the conventional molding apparatus shown in FIG.

Therefore, in the present invention, a refrigerant pipe 11 for direct cooling is provided in a portion of the graphite mold 1 corresponding to the ingot solidification zone 9, and a portion of the graphite mold 1 protruding from the water-cooled copper block 2 in FIG. The inlet end was replaced with a refractory heat insulating material 5a.

To provide the refrigerant conduit 11, a hole with a diameter of approximately 173 mm in thickness is bored at right angles to the casting direction approximately in the center of the graphite plate constituting the graphite mold 1 in the thickness direction, and a hole approximately equal to the diameter of the hole is drilled into the hole. A relatively thin-walled steel pipe with an outer diameter of 1 was press-fitted into the hole wall so that it was in close contact with the hole wall.

By passing high-pressure water through this refrigerant conduit 11, it is possible to directly remove heat from the graphite mold near the solidification zone, which is subject to the highest thermal load during casting, so it is possible to remove heat directly from the graphite mold, compared to the case where a water-cooled copper block is used alone. Cooling efficiency can be significantly increased.

Furthermore, in the present invention, since a thin-walled, small-diameter tube is used for the refrigerant conduit 11 that penetrates the graphite mold 1, the tube body itself is extremely flexible, so that if thermal deformation occurs in the graphite mold 1, Also, since the refrigerant conduit 11 can also be deformed freely in response to the deformation of the through hole drilled in the graphite mold 1, even if deformation due to this type of thermal distortion occurs, the adhesion between the two can be maintained. It is sufficiently retained and therefore does not cause a decrease in cooling efficiency.

More importantly, as mentioned above, the refrigerant conduit 11 is placed in the graphite mold 1 near the ingot solidification zone 9, which has the highest heat load and tends to reach high temperatures, so that this area can be efficiently cooled. , the deformation of both the graphite mold 1 and the water-cooled copper block 2 due to thermal strain is reduced, and the occurrence of gaps between them, that is, air gaps, is greatly reduced, so the cooling effect of the water-cooled copper block 2 itself is also greater than before. Furthermore, compared to conventional mold equipment, it is possible to distribute cooling water more rationally, and therefore, more efficient mold design is possible, resulting in improved casting productivity. This will bring about various excellent ripple effects, such as the expected improvement in the quality of life.

Note that the installation of the refrigerant pipe 11 in the graphite mold 1 is not limited to the vicinity of the ingot solidification zone 9 described above, but may be installed in the ingot solidification zone 9 or other locations depending on the size, shape, etc. of the ingot. It goes without saying that it can be provided at any location.

In addition, the fireproof heat insulating material 5a connected to the end of the molten metal inlet of the graphite mold 1 is such that the molten metal 8 introduced into the mold during casting is cooled directly by the conduit 11 of the graphite mold 1, so that the temperature rises rapidly near the inlet. The viscosity of the molten metal decreases and partially solidifies in this area, which prevents the molten metal from decreasing in viscosity and hindering operations. Materials that do not
For example, in the case of copper and copper alloys, high alumina castable is recommended.

The structure of the continuous casting mold apparatus of the present invention other than the above is similar to that of the conventional apparatus shown in FIG. 2, and therefore a description thereof will be omitted.

Next, examples of the present invention will be described.

(Example) When casting a plate-shaped continuous casting ingot of pure copper with a thickness of 18 mm and a width of 550 mm using a graphite mold device for horizontal continuous casting as shown in FIG. Using a graphite plate with a thickness of 30 mm, a predetermined cooling water flow path (not shown) is provided in the water-cooled copper block 2, and the thickness direction at positions 25 m and 75 mm from the molten metal inflow side end of the graphite mold 1 is approximately in the center. A thin-walled steel pipe with a wall thickness of 1.0 m, which has a diameter of 10 nmφ and a diameter slightly longer than the width of the mold, is drilled at right angles to the casting direction, that is, in the width direction, and has an outer diameter that is inscribed in the through hole. Push it in and insert it so that it protrudes from both ends of the mold in the width direction, each several tens of meters long, and connect each end to cooling water supply and drainage pipes (not shown).
Do not connect to The cooling water system in this case may be the same as the cooling water system for the conventional water-cooled copper block 2, but it should be an independent system in order to prevent conduit buckling and crushing due to thermal deformation of the mold during operation. It is desirable to use high pressure water.

Using the graphite mold apparatus A in which the graphite mold 1 is provided with the refrigerant pipe 11 in this way, the refrigerant is supplied to the pipe 11 at a temperature of 26
℃, pressure cuff kg/Cxn was supplied, pure copper molten metal at 1180℃ was charged into holding furnace B and introduced into graphite mold 1, and casting was performed at an average casting speed of 380 mm/min. Successful continuous casting was possible. This casting speed is an average casting speed of 100 to 20 when using a conventional mold device that relies only on the water-cooled copper block 2 for cooling.
0 ITffn/'m! It is about 21 to 3 times as large as n, indicating that the present invention can significantly improve casting productivity. The quality of the obtained plate-shaped ingot 10 was the same as that obtained by the conventional method, and no defects were observed.

Also, just to be sure, we measured the mold cooling capacity of the mold apparatus of the present invention and found that the mold surface temperature at the location where the refrigerant pipe 11 of the graphite mold 1 was installed was approximately 700°C, and the heat removal effect was extremely high. In addition, the amount of heat removed by the cooling water in the refrigerant pipe 11 is approximately 40 KCal/mark per width of the cast plate...
In, and when this is combined with the 40 to 60 Kcal/in of the heat carried away by the cooling water in the water-cooled copper block, it is found that the molding device according to the present invention has approximately twice the cooling capacity compared to the conventional molding device. That's right.

In addition, in this example, a fireproof insulation material 5a made of high alumina castable was continuously applied to the end face of the graphite mold 1 on the molten metal inlet side over a length of 50 mm in a tapered shape that expanded toward the holding furnace B side. By doing this, even if cooling water is introduced into the refrigerant pipe 11 of the graphite mold 1 before the start of casting, the molten metal near the molten metal inlet of the graphite mold 1 will solidify prematurely and enter the mold. It was confirmed that insufficient hot water supply was prevented and smooth casting could be performed. Moreover, no adverse effect on the graphite plate constituting the mold was observed due to cooling by the refrigerant pipe #111 in the graphite mold 1.

(Effects of the Invention) As described above, in the graphite mold apparatus for continuous casting of the present invention, by arranging a conduit through which a cooling medium flows in the graphite mold itself, in addition to cooling by a conventional water-cooled copper block, the graphite mold is Since we have made it possible to perform direct cooling, we are able to provide a molding device with high cooling efficiency not seen in conventional devices of this type, and its structure requires no major changes to the basic structure of the molding device. The graphite plate, which is a consumable material as a constituent material of the graphite mold, needs to be simply modified by machining and inserting a metal tube. Moreover, it is economical because the casting productivity can be greatly improved. It can be said that Invention 3 is extremely effective.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a main part showing one embodiment of the graphite mold device for continuous casting of metal ingots of the present invention, and FIG. 2 is a conceptual side sectional view of a conventional graphite mold device for continuous casting. be. 1...Graphite mold, 2...Water-cooled copper block, 3...
Steel covering material, 4a, 4b... Bolt, 5.5a...
Fireproof insulation material, 6... Holding furnace lining, 7... Sealing material, 8... Molten metal, 9... Solidification zone, 10...
Ingot, 11... refrigerant pipe, 12... frame material,
A... Mold equipment, B... Molten metal holding furnace

Claims (3)

[Claims] (1) Integrating a graphite mold for horizontal continuous casting to obtain a metal ingot, a water-cooled copper block that circumscribes the graphite mold to cool the mold, and a copper covering plate that reinforces the water-cooled copper block from the outside. A graphite mold device for continuous casting of metal ingots, which comprises a graphite mold and a pipe line for passing a cooling medium through the graphite mold. (2) The graphite mold apparatus for continuous casting of metal ingots according to claim 1, wherein the pipe line for passing the cooling medium is provided in a portion corresponding to the molten metal solidification zone of the graphite mold. (3) The graphite mold device for continuous casting of metal ingots according to claim 1 or 2, wherein a fireproof heat insulating material is continuously provided at the end of the graphite mold on the molten metal inflow side.