JP2015182111A - Casting apparatus for ingot and casting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a casting apparatus for ingots that can reduce entrainment of oxide and prepare stably a plurality of uniformly-shaped molten cast ingots at low costs and a casting method.SOLUTION: A casting apparatus 1 for ingots casts ingots by inpouring molten metal 21 produced by heating and melting a metal material 20 into a mold main body 3 through a nozzle 6 of a raw material dumping tank 2. The mold main body 3 comprises a storage chamber 31 and chambers 32 and 32 for ingot casting, where a space between bottom parts of the chambers 32 and 32 for ingot casting is communicated with the storage chamber 31 through a flowing groove 41 of a carbon sheet 4. Further, at an upper part of the mold main body 3 is formed an exhausting groove 36 that overflows the molten metal 21 flowing into the chambers 32 and 32 for ingot casting at a predetermined height.

Description

  The present invention relates to an ingot casting apparatus and a casting method apparatus capable of stably producing a plurality of melt-cast ingots with less oxide entanglement and uniform shape at low cost.

  When compound semiconductors such as bismuth tellurium and indium antimony are synthesized in large quantities at the mass production level, it is necessary to prepare a large number of metal raw materials (ingots) of a certain shape in advance in order to shorten the time for weighing the input raw materials. Is done. In order to produce a metal ingot having a fixed shape, it is necessary to provide a process such as casting. In that process, however, oxide entrainment, variation in shape, and the like may occur. For this reason, shortening of the weighing time may not be sufficiently achieved.

Further, when taking out a plurality of ingots obtained by melting and casting metal raw materials from a mold, the following problems may occur.
(1) Since the oxide adhering to the raw material is caught in the cast ingot, the oxygen concentration in the ingot does not decrease. If there is an oxygen concentrating part in part, time and labor are required because it is necessary to remove it in a later process.
(2) In order to make the sizes of the plurality of ingots the same, it is necessary to provide a molten metal through hole in the mold. However, if the through hole is large, the molten metal in the through hole is also solidified when the cast ingot is solidified. The work which cut | disconnects the solidification part of a through-hole is required after ingot casting.
(3) When the cast ingot is taken out from the mold, a part of the ingot is fixed to the mold surface, and in the case of a brittle metal, the ingot may be damaged.

  In addition, about the reduction | decrease of an impurity, it is shown by patent document 1, and in the refinement | purification method and refiner | purifier, the solution is aimed at by heating a metal in a mold in vacuum.

JP 2002-212647 A

  However, according to the conventional purification method and the purification apparatus of Patent Document 1, although the reduction of impurities is eliminated, there is a problem that other problems described above are not solved.

  Therefore, the present invention has been made in view of such problems, and provides an ingot casting apparatus and a casting method capable of stably producing a plurality of melt-cast ingots having a uniform oxide shape and a uniform shape at a low cost. The purpose is to do.

  In order to achieve the above object, the present invention according to claim 1 is an ingot casting apparatus for forming a plurality of metal ingots having a low oxygen concentration, a high purity, and a uniform shape, in order to cast the ingot. A raw material charging tank for storing the metal raw material, and a raw material charging tank, which has a storage chamber for storing molten metal obtained by heating and melting the metal raw material, and a plurality of ingot casting chambers are disposed adjacent to the storage chamber, Disposed in the upper part of the mold main body formed with a drain groove for overflowing the molten metal flowing into the ingot casting chamber to the drainage part, and arranged so that the bottom of the ingot casting chamber communicates with the bottom of the storage chamber Provided is an ingot casting apparatus comprising a carbon sheet having a formed distribution groove and a bottom plate for closely attaching the carbon sheet to a mold body. That.

  In order to achieve the above object, the present invention described in claim 2 is the ingot casting apparatus according to claim 1, wherein the raw material charging tank, the mold body, the carbon sheet and the bottom plate are formed of high purity carbon. It is characterized by.

  In order to achieve the above object, according to a third aspect of the present invention, there is provided the ingot casting apparatus according to the first or second aspect, wherein the ingot casting chamber is tapered so as to expand toward the upper side or the bottom side. It is characterized by.

  In order to achieve the above object, the present invention according to claim 4 is an ingot casting method for forming a plurality of metal ingots having a low oxygen concentration, a high purity, and a uniform shape. A step of accommodating the metal raw material in the raw material charging tank, a step of flowing a molten metal obtained by heating and melting the metal raw material in a reducing atmosphere or an inert atmosphere into a storage chamber connected to the raw material charging tank, and so as to be adjacent to the storage chamber A step of allowing the molten metal to flow into the ingot casting chamber through a flow groove formed so as to communicate the bottom of the plurality of ingot casting chambers and the bottom of the storage chamber, and the molten metal that has flowed into the ingot casting chamber Overflowing at a predetermined height, and cooling the molten metal flowing into the ingot casting chamber to solidify it into an ingot; It provides an ingot casting method comprising configured and a retrieving ingots.

  In order to achieve the above object, according to a fifth aspect of the present invention, in the ingot casting method according to the fourth aspect of the present invention, the ingot casting chamber is formed in a tapered shape expanding toward the upper side or the bottom side. Thus, the formed ingot can be easily taken out.

  According to the ingot casting apparatus and the casting method of the present invention, the metal raw material for casting into the ingot is once introduced into the storage chamber, and the molten metal is allowed to flow into the ingot casting chamber communicated at the bottom via the storage chamber. Since the molten metal that has flowed into the ingot casting chamber is allowed to overflow at a predetermined height, the oxide contained in the molten metal floats above the molten metal and remains in the storage chamber, and is removed from the ingot casting chamber by overflow. Therefore, there is an effect that it is possible to manufacture an ingot with little oxide inclusion. Further, since the shape of the ingot casting chamber is constant, there is an effect that a large number of melting and casting ingots having a uniform shape can be stably manufactured at low cost. Furthermore, the weighing time when an alloy is synthesized using the manufactured ingot can be shortened.

  Further, since the raw material charging tank, the mold body, the carbon sheet and the bottom plate constituting the casting mold are formed of high purity carbon, there is an effect that the ingot is prevented from being contaminated.

  Furthermore, since the ingot casting chamber is formed in a tapered shape that expands toward the upper side or the bottom side, even if the formed ingot is a brittle metal, it can be easily taken out without being damaged. .

It is a longitudinal section showing one embodiment of an ingot casting device concerning the present invention. It is AA sectional drawing of the ingot casting apparatus shown in FIG. It is a flowchart which shows each process of the ingot casting method using the ingot casting apparatus shown in FIG.

  Hereinafter, an ingot casting apparatus and a casting method according to the present invention will be described in detail based on a preferred embodiment. FIG. 1 is a sectional view showing an embodiment of an ingot casting apparatus according to the present invention, and FIG. 2 is a sectional view taken along line AA of the ingot casting apparatus shown in FIG.

[Configuration of ingot casting machine]
The illustrated ingot casting apparatus 1 generally includes a raw material charging tank 2 for storing a metal raw material 20 for casting into an ingot, and a storage chamber 31 for storing a molten metal 21 obtained by heating and melting the metal raw material 20. A mold body 3 in which a plurality of (12 chambers in this embodiment) ingot casting chambers 32, 32 are disposed so as to surround 31 and a bottom surface of the storage chamber 31 and a plurality of ingot castings. The carbon sheet 4 is provided with a flow groove 41 that communicates with the bottoms of the chambers 32, 32, and a square plate-like bottom plate 5 that tightly attaches the carbon sheet 4 to the mold body 3.

  A nozzle 6 for pouring a molten metal 21 obtained by heating and melting the metal raw material 20 into the storage chamber 31 is attached to the raw material charging tank 2. Further, on the upper side of the mold body 3, a discharge that causes a part of the molten metal 21 that has flowed from the bottom of the storage chamber 31 to the bottom of each ingot casting chamber 32, 32 through the flow groove 41 to overflow into the drainage portion 33. Grooves 36, 36 are provided. The storage chamber 31 and each ingot casting chamber 32, 32 are separated from each other except that they are communicated with each other by a flow groove 41. The drainage part 33 is arranged so as to surround the mold body 3 so as to be adjacent to the ingot casting chambers 32, 32. In the above configuration, each of the raw material charging tank 2, the mold body 3, the carbon sheet 4, and the bottom plate 5 is made of high-purity carbon in order to prevent contamination of the ingot.

  Inside the mold body 3, partition-like partition members 34, 34 for separating the storage chamber 31 and the plurality of ingot casting chambers 32, 32 are provided, and a side wall that forms a drainage portion 33 on the outer periphery. Portions 35 and 35 are erected. Further, the discharge groove 36 for overflowing the molten metal 21 to the drainage part 33 is at the same height position on the upper side of the mold body 3 in order to make the size of the ingot cast in each ingot casting chamber 32, 32 uniform. Is provided.

  The ingot casting chambers 32, 32 are provided with a taper that expands toward the bottom so that the ingot after casting can be easily taken out from the ingot casting chambers 32, 32. In addition, when the raw material charging tank 2 is formed so as to be removable, it can be formed so as to be taken out from the upper side by providing a taper that expands toward the upper side of the ingot casting chambers 32, 32.

  The carbon sheet 4 is a plate-like member formed of high-purity carbon, and opening-shaped flow grooves 41 and 41 are provided in a predetermined region of the carbon sheet 4. The carbon sheet 4 is firmly fixed to the bottom surface of the mold body 3 by a plurality of bolts (carbon bolts) 7 and 7 so that the molten metal 21 does not leak out of the mold.

[Ingot casting method]
Next, the operation of the above-described ingot casting apparatus 1 and a method for casting the ingot will be described with reference to FIG. FIG. 3 is a flowchart showing each step of the ingot casting method using the ingot casting apparatus shown in FIG.

  First, the metal raw material 20 is accommodated in the raw material charging tank 2, and the ingot casting apparatus 1 containing the metal raw material 20 is accommodated in a resistance heating furnace (not shown). After making the atmosphere in the resistance heating furnace (not shown) into a reducing atmosphere or an inert atmosphere, the ingot casting apparatus 1 is heated and melted to a temperature equal to or higher than the melting point of the metal raw material 20 (step S1).

  The molten metal raw material 20 in the raw material charging tank 2 becomes a molten metal 21 and flows into the storage chamber 31 through the nozzle 6 provided at the bottom of the raw material charging tank 2. Here, since the specific gravity of the oxide 22 contained in the molten metal 21 flowing into the storage chamber 31 is lighter than that of the molten metal, the oxide 22 floats above the storage chamber 31. Therefore, the oxide 22 does not flow out to the adjacent ingot casting chamber 32 but stays only in the storage chamber 31. At this time, since the carbon sheet 4 provided with the flow grooves 41 exists below the storage chamber 31 and the plurality of ingot casting chambers 32, 32, the molten metal 21 that does not include the oxide 22 is provided through the flow grooves 41. It flows into the ingot casting chambers 32, 32 (step S2).

  The upper side of the molten metal 21 gradually accumulated in the ingot casting chambers 32 and 32 eventually overflows into the drainage part 33 via the discharge groove 36 provided in the upper part of the ingot casting chambers 32 and 32 (step S3). The height of the molten metal 21 in the plurality of ingot casting chambers 32, 32 can be made uniform. Thereby, the size of the ingot cast can be made uniform. Even if the molten metal 21 stored in the ingot casting chambers 32 and 32 contains oxides, the upper side of the molten metal 21 is discharged to the drainage part 33 through the discharge groove 36 due to overflow. Therefore, an oxide-free ingot can be produced. Even if there is a minute gap between the bottom plate 5, the storage chamber 31, and the ingot casting chamber 32, the molten metal 21 does not leak because the carbon sheet 4 is provided.

  Note that when the thin carbon sheet 4 is used, the depth of the flow groove 41 is also shallow, and therefore it may take time to flow into the adjacent ingot casting chambers 32 and 32. Therefore, when the molten metal 21 injected from the raw material charging tank 2 into the storage chamber 31 overflows from the storage chamber 31, the diameter of the nozzle 6 of the raw material charging tank 2 is reduced or the height of the storage chamber 31 is increased. It is preferable to make adjustments as appropriate.

  Thereafter, the molten metal flowing into the ingot casting chambers 32, 32 is cooled to solidify to form an ingot (not shown) (step S4). Then, after separating the raw material charging tank 2 and the mold body 3, the mold body 3 and the ingots in the ingot casting chambers 32, 32 are pushed out by a dedicated device or manually, and the ingot is removed from the mold body 3 and the ingot casting chambers 32, 32. Remove (step S5) and move to storage location. At this time, since the ingot casting chambers 32 and 32 are provided with a taper, they can be easily taken out by pushing in the expanding direction. This completes the ingot casting. The ingot formed by the storage chamber 31 is not used as a product because the oxide in the molten metal floats on the top.

  As described above, according to the ingot casting apparatus and the casting method of the present invention, the mold body 3 is disposed in the lower part of the raw material charging tank 2, the storage chamber 31 is formed in the center of the mold body 3, and the storage chamber 31. A plurality of ingot casting chambers 32, 32 are arranged so as to surround the outside of the mold body, and the carbon sheet 4 in which the flow grooves 41 are formed on the bottom surface of the mold body 3 is detachably attached, so that the oxide is less involved. In addition, there is an effect that a large number of melt-cast ingots that are uniform in shape and easy to take out can be stably produced at low cost.

  Next, the Example which cast the ingot using the ingot casting apparatus 1 mentioned above is described. The present inventors used the ingot casting apparatus 1 shown in FIGS. 1 and 2 and made a 4N-Te raw material having a size of about 50 × about 45 × about 35 mm with a lower end of 24.8 × 24.8 and an upper end of 25 Melting casting of 12 Te ingots having a taper shape with a size of 0.0 × 25.0 and a height of 125 mm was performed. First, 16 pieces of about 500 g of 4N-Te blocks were put into the raw material charging tank 2, and the ingot casting apparatus 1 was set inside a resistance heating furnace (not shown). Then, after evacuating the inside of the furnace, 5N hydrogen gas was allowed to flow for 30 minutes to sufficiently replace the atmosphere in the furnace with hydrogen, and then the temperature was raised to 650 ° C. at a temperature rising rate of 10 ° C./1 minute. The Te block starts melting at 450 ° C. or higher during the temperature increase. The molten metal 21 flows into the storage chamber 31 through the nozzle 6 provided in the lower part of the raw material charging tank 2. Since the oxide 22 is mixed in the molten metal 21 injected from the nozzle 6, the oxide 22 having a lighter specific gravity than the molten metal floats above the molten metal 21 in the storage chamber 31.

  The molten metal 21 on which the oxide 22 floats passes through the flow grooves 41 of the carbon sheet 4 having a thickness of 0.5 mm provided in the lower portions of the ingot casting chambers 32 and 32 and flows into the adjacent ingot casting chambers 32 and 32. . Thereafter, the molten metal 21 is made to overflow into the drainage part 33 through the discharge groove 36 provided in the upper part of the ingot casting chambers 32, 32, whereby the height of the molten metal 21 in each ingot casting chamber 32, 32 is made uniform.

  Then, after holding the temperature of 650 ° C. for 60 minutes, the heater power supply of the resistance heating furnace is turned off and the furnace is cooled down. Removed inside. Thereafter, the bolts 7 and 7 were removed to separate the raw material charging tank 2 from the mold body 3, and the carbon sheet 4 at the lower part of the ingot casting chambers 32 and 32 was removed. At this time, the molten metal 21 accumulated in the flow groove 41 is solidified to have a convex shape, but the convex portion has a thin plate shape with a thickness of about 1 mm, and therefore can be easily removed by using a spatula. Can do. After removing the convex portions, by pushing the lower part of the ingot, the ingots (12 pieces) in the ingot casting chambers 32 and 32 could be easily taken out without being damaged.

  The casting by the above was carried out, and the measured values of 12 heights are shown in Table 1. The average value was 124.97 mm, and the variation was a standard deviation with a very small variation of 0.22 mm (the relative variation coefficient of the height of the ingot cast in this example was 0.176). %Met). As for the oxygen concentration, when a sample was cut out from the upper part of the ingot and subjected to gas analysis by the LECO method (infrared absorption spectroscopy), good results of 10 ppm or less were obtained in all cases. On the other hand, when the oxygen concentration was analyzed for the upper part of the Te ingot solidified in the storage chamber 21, it was 70 ppm, which is a higher value than the product part.

DESCRIPTION OF SYMBOLS 1 Ingot casting apparatus 2 Raw material charging tank 3 Mold body 4 Carbon sheet 5 Bottom plate 6 Nozzle 7 Bolt 10 Ingot casting apparatus 11 Raw material charging tank 12 Carbon sheet 20 Metal raw material 21 Molten metal 22 Oxide 31 Storage chamber 32 Ingot casting chamber 33 Drainage part 34 Partition member 35 Side wall 36 Discharge groove 41 Distribution groove

Claims (5)

An ingot casting apparatus for forming a plurality of metal ingots having a low oxygen concentration and high purity and uniform shape,
A raw material charging tank for storing a metal raw material for casting into an ingot;
The molten metal that is in communication with the raw material charging tank and has a storage chamber for storing a molten metal obtained by heating and melting the metal raw material, and a plurality of ingot casting chambers are disposed adjacent to the storage chamber, and flows into the ingot casting chamber A mold body with a drain groove formed on the top to overflow the drainage part,
A carbon sheet disposed on the bottom surface of the mold body, and formed with a flow groove formed to communicate the bottom of the ingot casting chamber and the bottom of the storage chamber;
A bottom plate for closely attaching the carbon sheet to the mold body;
An ingot casting apparatus comprising: In the ingot casting apparatus according to claim 1,
The ingot casting apparatus, wherein the raw material charging tank, the mold main body, the carbon sheet and the bottom plate are made of high purity carbon. In the ingot casting apparatus according to claim 1 or 2,
The ingot casting chamber is an ingot casting apparatus characterized in that the ingot casting chamber has a taper shape expanding toward the upper side or the bottom side. An ingot casting method for forming a plurality of metal ingots having a low oxygen concentration, high purity, and uniform shape,
Storing a metal raw material for casting into an ingot in a raw material charging tank;
Flowing a molten metal obtained by heating and melting the metal raw material in a reducing atmosphere or an inert atmosphere into a storage chamber communicated with the raw material charging tank;
The molten metal is allowed to flow into the ingot casting chamber through a flow groove formed so as to communicate the bottom of the plurality of ingot casting chambers arranged adjacent to the storage chamber and the bottom of the storage chamber. Steps,
Overflowing the molten metal flowing into the ingot casting chamber at a predetermined height;
Solidifying the molten metal flowing into the ingot casting chamber by cooling it into an ingot;
Removing the ingot;
An ingot casting method, comprising: In the ingot casting method according to claim 4,
An ingot casting method characterized in that the ingot casting chamber is formed in a tapered shape that expands toward the upper side or the bottom side, so that the formed ingot can be easily taken out.

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