JP2000274957A - Electron beam fusion furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron beam fusion furnace which can minimize the thermal influence, and can prevent the transformation, fusion, and, damage accident of constituent parts, and further can raise the yield in manufacture of a produced ingot. SOLUTION: In an electron beam fusion furnace 1a which forms a specified dimension of ingot by accumulating metallic material 2 heated and fused by an electron beam 3 on the topside of an ingot base 5a, and cooling and solidifying the fused metallic material 2 by a cooling mold 6 arranged around the ingot base 5a, and drawing a connection metal fitting 7a mounted and fixed to the bottom of the ingot base 5a gradually in downward direction, a fixing plate 11 to fix the connection metal fitting 7a to the ingot base 5a is attached to the bottom of the ingot base 5a, and also the fixing plate 11 is fixed to the periphery of the bottom of the ingot base 5a by a plurality of fixing means 12 arranged around it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam melting furnace.
The present invention relates to an electron beam melting furnace capable of effectively preventing damage accidents and increasing the production yield of ingots to be produced.

[0002]

2. Description of the Related Art An electron beam generated from an electron gun (EB gun) is applied to a raw material which is a high melting point metal (refractory metal) such as W, Mo, Ta, Ti, Pt, etc. to heat and melt the material. BACKGROUND ART An electron beam melting furnace for cooling and solidifying to prepare a metal ingot or an alloy ingot of a predetermined size is widely used. In the melting treatment in the above-mentioned electron beam melting furnace, while preventing deterioration due to oxidation of metal, scattering of evaporated atoms by gas, mixing of impurities into an ingot, and scattering of an electron beam (EB),
In order to normally secure the path, the processing atmosphere is usually kept at a vacuum. According to the above-mentioned electron beam melting furnace, it is possible to prepare a high-purity metal or alloy ingot with less contamination particularly by impurities.

FIG. 2 is a sectional view showing a structural example of a conventional electron beam melting furnace. The electron beam melting furnace 1 includes an electron beam generator (EB gun) 4 for generating an electron beam (EB) 3 for irradiating a raw material 2, an ingot base 5 for receiving a metal material melted by the electron beam 3, A cooling die 6 made of copper, which is arranged around the ingot base 5 and cools and solidifies the melted metal material. Cooling water is supplied to the cooling die 6 to keep the surface temperature of the cooling die 6 constant. A connection fitting 7 is integrally attached to the bottom of the ingot base 5 by a screwing structure. A pin 8 is provided at a protruding end of the connection fitting 7, and an upper end of the drawing shaft 9 and a protrusion of the connection fitting 7 are connected by pin connection.

In the electron beam melting furnace 1 as described above, the raw material 2 supplied into the furnace by the side charge method is heated and melted by being irradiated with the electron beam 3 from the electron beam generator 4, and melted. The metal material is sequentially deposited on the upper surface of the ingot base 5. The deposited metal material forms a high-temperature fusion zone 10 on the upper surface of the ingot base 5. The melted portion 10 is sequentially cooled and solidified on the inner surface of the cooling mold 6 disposed around the ingot base 5, and is integrated with the ingot base 5. In parallel with this cooling / solidification operation, the drawing shaft 9 descends while rotating at a low speed. Therefore, the ingot base 5 whose axial length has been increased is pulled downward through the connection fitting 7. The ingot base 5 is removed at the time when the ingot base 5 has grown to a predetermined length by repeating the above-mentioned melting operation and cooling / solidification operation of the raw material, and cut near the upper end of the connection fitting 7 to have a predetermined diameter. Is obtained. Further, by cutting the ingot to a predetermined thickness, a plurality of metal plates such as sputtering targets are prepared.

[0005]

However, in the above-mentioned conventional electron beam melting furnace, the connection fitting is fixed to the center of the bottom of the ingot base by screwing.
Since the high-temperature metal melting part is formed deeper in the center of the ingot base, the screw part of the connection fitting fixed to the center is easily affected by heat, and is easily deformed or melted and damaged. There are disadvantages, making it difficult to attach and detach the connection fittings,
There is a problem that the connection fitting cannot be used repeatedly.

On the other hand, if the thickness of the ingot base is previously set to be large in order to avoid the above-mentioned thermal effects, the maximum length of the ingot in the melting furnace is restricted. , The length of the product ingot is shortened. Therefore, there is also a problem that the production yield of products such as a target plate obtained by one ingot preparation is reduced.

Further, in the conventional electron beam melting furnace, since the connecting fitting is attached to the bottom of the ingot base by screwing, the raw material is melted while rotating the drawing shaft to rotate the ingot base. When connecting, the screw connection of the connection fitting is loosened, the rotation of the ingot base does not proceed smoothly, or in the worst case, the connection fitting comes off the ingot base, making the ingot preparation operation impossible, There was also a problem that a great deal of labor was required for restoration work.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and can minimize heat effects, can effectively prevent deformation, melting, and damage of components, and furthermore, can produce ingots at a high yield. It is an object of the present invention to provide an electron beam melting furnace capable of increasing the melting point.

[0009]

In order to achieve the above object, an electron beam melting furnace according to the present invention deposits a metal material heated and melted by an electron beam on an upper surface of an ingot base and arranges the metal material around the ingot base. The molten metal material is cooled and solidified by the cooled cooling mold, and the connection fittings fixed to the bottom surface of the ingot base are sequentially pulled downward to form an ingot of a predetermined size in the electron beam melting furnace. A fixing plate for fixing a metal fitting to the ingot base is attached to the bottom surface of the ingot base, and the fixing plate is fixed at the outer peripheral portion of the bottom surface of the ingot base by a plurality of fixing means arranged on the outer peripheral portion. It is characterized by being.

The connection fitting and the fixing plate are preferably formed of a refractory metal having a higher melting point than the metal material to be heated and melted. Further, the connection fitting and the fixing plate are made of niobium (N
b), at least one refractory metal selected from molybdenum (Mo) and tungsten (W).

[0011] Further, it is possible to form the main body of the connection fitting into a prismatic shape, form a square hole in the center of the fixing plate, and fit the prismatic body of the connection fitting into the square hole. Good.

In the present invention, a heat-resistant Ni-based material such as Inconel or a Ni-based superalloy may be used as a material for forming the connection fitting and the fixing plate, but the melting point is higher than the melting point of the melting metal material. Material, preferably,
By using a refractory metal material having a high melting point of at least 1000 ° C. or more, deformation, damage, and the like due to heat can be more effectively prevented. As the refractory metal, at least one metal material selected from niobium (Nb), molybdenum (Mo), and tungsten (W) or an alloy thereof is preferable. In particular, since Nb has a property of being less likely to be cracked as compared with Mo and W, it is preferable as a constituent material of the connection fitting and the fixing plate. Ta-W
Alloys are preferred because of their excellent high-temperature strength.

Further, the main body of the connection fitting is formed, for example, in the shape of a square pole, while a square hole is formed in the center of the fixing plate, and the square pillar-shaped main body of the connection fitting is fitted into the square hole. Accordingly, even when the extraction shaft is rotated, the connection fitting is reliably rotated together with the extraction shaft, and the ingot base can be smoothly rotated.

According to the electron beam melting furnace having the above configuration, the fixing plate for fixing the connection fitting to the ingot base is fixed to the outer periphery of the bottom surface of the ingot base by a plurality of fixing means arranged on the outer periphery. Because of the fixed structure, the fixing means is disposed at a position away from the high-temperature metal fusion zone. Therefore, it is possible to minimize the influence of heat acting on the fixing means, and it is possible to effectively prevent deformation, melting and damage of the fixing means.

[0015] Further, since a fine screw portion is not formed in the connection fitting disposed at the central portion where the heat is greatly affected, it is not difficult to remove the connection fitting due to thermal damage of the screw portion. Furthermore, the connection fitting can be used repeatedly even when it is affected by heat.

Furthermore, since the fixing plate is joined to the bottom surface of the ingot base by a plurality of fixing means, the length of the fixing means inserted into the ingot base is reduced. Therefore, the initial length of the ingot base can also be minimized, and the length of the generated product ingot can be increased, and the production yield of the metal plate obtained by cutting the product ingot can be significantly increased. Also becomes possible.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be specifically described with reference to the accompanying drawings according to the following embodiments. FIG. 1 is a sectional view showing one embodiment of an electron beam melting furnace according to the present invention.

That is, the electron beam melting furnace 1a according to the present embodiment uses the Ti raw material as the metal material 2 heated and melted by the electron beam 3 generated by the electron beam generator 4,
Similarly, the molten metal material 10 is deposited on the upper surface of the ingot base 5a made of Ti, and the molten metal material 10 is cooled and solidified by the copper cooling mold 6 arranged around the ingot base 5a.
Connection metal fitting 7a attached and fixed to the bottom of ingot base 5a
Are sequentially pulled downward to form an ingot of a predetermined size in the electron beam melting furnace 1a, and a fixing plate 11 for fixing the connection fitting 7a to the ingot base 5a is attached to a bottom surface of the ingot base 5a.
The fixing plate 11 is configured to be fixed at the outer peripheral portion of the bottom surface of the ingot base 5a by fixing bolts as six fixing means 12 arranged on the outer peripheral portion.

The fixed plate 11 is provided on the ingot base 5.
It is formed in a disk shape having the same diameter (80 to 230 mm) as a. Further, the connection metal 7a and the fixing plate 11 are made of a Ti material (melting point 1
It is formed of niobium (Nb) (melting point: about 2700 ° C.) as a refractory metal having a melting point higher than 677 ° C.).
The six fixing bolts 12 were made of heat-resistant Ni alloy.

The main body of the connection fitting 7a is formed in the shape of a quadrangular prism, while a square hole is formed in the center of the fixing plate 11, and the square column-shaped main body of the connection fitting 7a is fitted into the square hole. I agree. Further, the protruding portion of the connection fitting 7a and the upper end portion of the extraction shaft 9 are integrally connected by a pin 8.

The operation of preparing a large-diameter high-purity Ti ingot using the electron beam melting furnace 1a having the above-described structure is as follows. That is, the Ti raw material 2 is irradiated with the electron beam 3 generated by the electron beam generator 4 to be heated and melted. The melted Ti material is sequentially deposited on the upper surface of the ingot base 5a to form a molten portion 10. The melted portion 10 deposited on the ingot base 5a is sequentially cooled and solidified by the copper cooling mold 6 disposed therearound. At this time, in order to make the molten portion uniform, the drawing shaft 9 is rotated at a slow speed to rotate the entire ingot base 5a, and at the same time, the drawing shaft 9 is lowered to pull out the ingot portion generated downward.

According to the electron beam melting furnace 1a according to the above embodiment, the fixing plate 11 for fixing the connection fitting 7a to the ingot base 5a is fixed to the ingot base by the six fixing bolts 12 arranged on the outer periphery thereof. The fixing bolt 12 is disposed at a position distant from the high-temperature metal melting portion 10 because the fixing is performed at the outer peripheral portion of the bottom surface of the table 5a. Therefore, it is possible to minimize the thermal effect acting on the fixing bolt 12, and it is possible to effectively prevent the fixing bolt 12 from being deformed, melted, or damaged.

In particular, as shown in FIG. 1, the melted portion 10 of the ingot is deepest at the center and as the diameter of the ingot increases from 80 mm to 230 mm,
Since the fixing bolt 11 is further deepened, the fixing bolt 12 for attaching the fixing plate 11 is separated from the center position and is arranged on the outer peripheral portion, so that the influence of heat from the high-temperature melting portion 10 can be reduced.

That is, the deepest part (central part) of the fusion part 10
By maximizing the distance from the fixing bolt 12 to the fixing bolt 12, the temperature near the fixing bolt 12 decreases, and the fixing plate 11
Sufficient strength for maintaining the shape of the connection fitting 7a is obtained.

Further, since the connection fitting 7a disposed at the central portion where the thermal influence is large is not formed with a fine thread, it is not difficult to remove the connection fitting 7a due to thermal damage of the screw. . Furthermore, even when the connection fitting 7a is affected by heat, it can be used repeatedly as long as its deformation is small.

Further, the fixing plate 11 includes a plurality of fixing bolts 1.
2, the fixing bolt 12 is joined to the bottom surface of the ingot base 5a, so that the fixing force required per fixing bolt can be reduced, and the length of the fixing bolt 12 inserted into the ingot base 5a is shortened. Therefore, the initial length of the ingot base 5a can be minimized, and the length of the generated product ingot can be increased, and the production yield of the metal plate obtained by cutting the product ingot can be greatly increased. It becomes possible.

Further, since the main body of the connection fitting 7a is formed in the shape of a quadrangular prism and is fixed so as to fit into the square hole formed in the fixing plate 11, the drawing shaft 9 is rotated to move the ingot base 5a. Even when the metal material is melted while being rotated, there is no possibility that the connection fitting 7 will be disengaged or the transmission of the rotational force for rotating the ingot base 5a becomes difficult as in the related art.

Using the melting furnace of this embodiment, the diameter is 80 mm.
~ 230mm Ti ingot was manufactured respectively,
Except for slight damage to the fixing bolts 12 as consumables, no deformation or damage occurred to the connection fitting 7a and the fixing plate 11. In particular, according to the melting furnace according to the present embodiment, in addition to being able to prevent an accident related to the connection structure between the ingot base and the furnace body, the initial length of the ingot can be minimized, and the ingot can be manufactured by one ingot preparation. The number of possible metal plates could be greatly increased, and the production yield of metal plates could be increased. In addition, in handling ingot replacement and the like, the labor load and the risk of the operator could be reduced.

In the above embodiment, the connection fitting 7
Although an example is shown in which a and the fixing plate 11 are formed of niobium (Nb), which is a refractory metal, it is confirmed that substantially the same effect can be obtained when molybdenum (Mo) and tungsten (W) are formed. did it.

[0030]

As described above, according to the electron beam melting furnace of the present invention, the fixing plate for fixing the connection fitting to the ingot base is fixed to the ingot base by a plurality of fixing means arranged on the outer peripheral portion thereof. Since the structure is fixed at the outer peripheral portion of the base surface, the fixing means is arranged at a position away from the high-temperature metal melting portion. Therefore, it is possible to minimize the influence of heat acting on the fixing means, and it is possible to effectively prevent deformation, melting and damage of the fixing means.

Further, since a fine screw portion is not formed in the connection fitting disposed at the central portion where the heat is greatly affected, it is not difficult to remove the connection fitting due to thermal damage of the screw portion. Furthermore, the connection fitting can be used repeatedly even when it is affected by heat.

Further, since the fixing plate is joined to the bottom surface of the ingot base by a plurality of fixing means, the length of the fixing means inserted into the ingot base is reduced. Therefore, the initial length of the ingot base can also be minimized, and the length of the generated product ingot can be increased, and the production yield of the metal plate obtained by cutting the product ingot can be significantly increased. Also becomes possible.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of an electron beam melting furnace according to the present invention.

FIG. 2 is a sectional view showing a structural example of a conventional electron beam melting furnace.

[Explanation of symbols]

 1,1a Electron beam melting furnace 2 Raw material 3 Electron beam (EB) 4 Electron beam generator (EB gun) 5,5a Ingot base 6 Cooling type (copper cooling type) 7,7a Connection metal 8 Pin 9 Pulling shaft 10 Melting Part 11 Fixing plate 12 Fixing means (fixing bolt)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C22B 9/22 C22B 9/22

Claims (4)

[Claims] 1. A metal material heated and melted by an electron beam is deposited on an upper surface of an ingot base, and the molten metal material is cooled and solidified by a cooling mold disposed around the ingot base, and the metal material is formed on the bottom surface of the ingot base. In an electron beam melting furnace for forming an ingot of a predetermined size by sequentially pulling the attached and fixed connecting fittings downward, while attaching a fixing plate for fixing the connecting fitting to the ingot base to the bottom surface of the ingot base, An electron beam melting furnace characterized in that the fixing plate is fixed at the outer peripheral portion of the bottom surface of the ingot base by a plurality of fixing means arranged at the outer peripheral portion. 2. The electron beam melting furnace according to claim 1, wherein the connection fitting and the fixing plate are formed of a refractory metal having a higher melting point than the metal material to be heated and melted. 3. The connecting fitting and the fixing plate are made of niobium (N
2. An electron beam melting furnace according to claim 1, wherein said furnace is made of at least one refractory metal selected from b), molybdenum (Mo) and tungsten (W). 4. A main body of the connection fitting is formed in a prismatic shape, while a square hole is formed in a central portion of the fixing plate, and the prismatic body of the connection fitting is fitted into the square hole. The electron beam melting furnace according to claim 1, wherein