Method for manufacturing graphite electrodes, electrodes, and quartz glass crucibles

Abstract

To provide a graphite electrode capable of reusing a concave connection part for connecting the graphite electrode in a small electrode device after using and exhausting the concave connection part in a large electrode device.SOLUTION: A graphite electrode used for arc discharge for manufacturing a quartz glass crucible includes a connection part connected to an electrode device for energizing the graphite electrode through the connection part. The connection part includes a first connection part and a second connection part different from the first connection part; the second connection part is smaller than the first connection part; the first connection part has a shape connected to a first electrode device; and the second connection part has a shape connected to a second electrode device smaller than the first electrode device.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a graphite electrode, an electrode, and a quartz glass crucible.

Background Art

[0002] Many silicon single crystals used as substrates for single crystal semiconductor materials are manufactured by the so-called Czochralski method in which silicon polycrystal is melted in a quartz glass crucible, brought into contact with a seed crystal, and then crystal growth is carried out. There are several types of quartz glass crucibles used in this method for manufacturing silicon single crystals. Practically, a quartz glass crucible manufactured by filling silicon dioxide powder (raw material quartz powder) along the inner peripheral surface of a rotatable hollow mold and heating and melting the silicon dioxide powder by arc discharge using a graphite electrode while rotating the mold is used. Many aspects have been disclosed regarding the graphite electrode used for arc discharge for manufacturing a quartz glass crucible (for example, Patent Documents 1 to Patent Documents 3).

[0003] This graphite electrode is used by being connected to an electrode device (for example, made of copper) for energization, and there are a plurality of connection methods. For example, a connection portion which is a protrusion called a nipple or the like is provided on the graphite electrode and driven into the electrode device, or a male screw is provided on the graphite electrode and a female screw is provided on the electrode device and screwed together, so that the graphite electrode is connected to and supported by the electrode device.

[0004] Figure 6 shows a schematic diagram of how a graphite electrode is connected to an electrode device by being driven into it. As shown in Figure 6(a), the graphite electrode 111 has a connection part 114, which is a projection called a nipple, on the graphite electrode body 112. The graphite electrode body 112 can have various shapes, such as cylindrical. The connection part 114 can also have various shapes, such as cylindrical, conical, or polygonal prism. As shown in Figure 6(b), the electrode device 151 has a concave connection part 156 that matches the size and shape of the connection part 114 of the graphite electrode 111. The electrode device 151 can also have various shapes, such as cylindrical. As shown in Figure 6(c), the graphite electrode 111 and the electrode device 151 are connected by being driven into them by external force, with the shapes of the connection part 114 and the concave connection part 156 aligned.

[0005] Figure 7 shows a schematic diagram of how a graphite electrode is screwed into an electrode device. As shown in Figure 7(a), the graphite electrode 121 is provided with a connection portion 124 having a male screw shape on the graphite electrode body 122. The external shape of the graphite electrode body 122 can be various, such as cylindrical, as in the case of Figure 6(b). Also, as shown in Figure 7(b), the electrode device 161 has a concave connection portion 166 with a female screw shape that can be screwed into the thread of the connection portion 124 of the graphite electrode 121. The external shape of the electrode device 161 can be various, such as cylindrical, as in the case of Figure 6(b). The graphite electrode 121 and the electrode device 161 are connected by screwing them together at the connection portion 124 and the concave connection portion 166, as shown in Figure 7(c).

[0006] In both the drive-in method shown in Figure 6 and the screw-in method shown in Figure 7, the graphite electrodes used for arc discharge to manufacture quartz glass crucibles are consumed by oxidation and become smaller in size, and are therefore, in principle, discarded after use. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2016-011238 [Patent Document 2] Japanese Patent Publication No. 2017-065962 [Patent Document 3] Japanese Patent Publication No. 2009-161362 [Overview of the project] [Problems that the invention aims to solve]

[0008] The embedded method of connecting graphite electrodes to electrode devices, as shown in Figure 6, is used for relatively small graphite electrodes, while the screw-type connection method, as shown in Figure 7, is used for relatively large graphite electrodes.

[0009] The degree of oxidation and wear of graphite electrodes due to arc discharge varies depending on the usage conditions, especially the usage time. After manufacturing one quartz glass crucible, depending on the shape of the graphite electrode, it may be possible to reuse it to manufacture another quartz glass crucible.

[0010] However, there was a problem in that the graphite electrodes could not be reused in electrode devices with different connection configurations between the graphite electrodes and the electrode device. For example, the screw-type graphite electrode 121 in Figure 7(a) can be applied to the electrode device 161 in Figure 7(b), but it cannot be applied to the implant-type electrode device 151 in Figure 6(b). Furthermore, the size of the connection part formed on the graphite electrode also limits the applicable electrode devices. As a result, there was a problem in that the degree of freedom in reusing graphite electrodes was low.

[0011] More specifically, the following issues arise. Graphite electrodes for arc discharge used in manufacturing quartz glass crucibles typically have a screw-threaded connector 124 (see Figure 7(a)) which allows for a relatively large graphite electrode body 122, making them suitable for manufacturing quartz glass crucibles requiring long arc discharge times. On the other hand, electrodes with a press-fit connector 114 (see Figure 6(a)) are suitable for applications requiring relatively short arc discharge times and have a relatively small graphite electrode body 112. As described above, when the graphite electrode 121 connected to the electrode device 161 shown in Figures 7(b) and (c) is used for arc discharge, the graphite electrode body 122 becomes smaller due to wear. When reusing this worn-out graphite electrode 121, even if there is still a short remaining usage time, it is sometimes necessary to discard it because the remaining usable time is too short to connect it to the electrode device 161 shown in Figure 7(b). Because the connection method is different, it is not possible to reuse the graphite electrode 121, which has been reduced in size by connecting it to an electrode device 151 as shown in Figure 6(b).

[0012] The present invention has been made in view of the above circumstances, and aims to provide a graphite electrode that can be reused in an electrode device with a small recessed coupling portion after being used and worn out in an electrode device with a large recessed coupling portion for connecting to a graphite electrode. [Means for solving the problem]

[0013] The present invention has been made to solve the above problems, and provides a graphite electrode used in arc discharge for manufacturing quartz glass crucibles, wherein the graphite electrode is equipped with a connection part and is connected via the connection part to an electrode device for supplying current to the graphite electrode, the connection part having a first connection part and a second connection part different from the first connection part, the second connection part being smaller than the first connection part, the first connection part having a shape that can be connected to a first electrode device, and the second connection part having a shape that can be connected to a second electrode device which is smaller than the first electrode device.

[0014] Since the graphite electrode of the present invention has a second connection part that is smaller than the first connection part, after the first connection part is connected to the first electrode device and an arc discharge is performed and the electrode is consumed, the second connection part can be connected to the second electrode device and an arc discharge can be performed again.

[0015] In this case, the first connecting portion and the second connecting portion may have a screw thread shape or a cylindrical shape.

[0016] The first and second connecting parts are preferably a combination of these shapes.

[0017] Furthermore, the present invention provides an electrode in which any of the above-described graphite electrodes and the first electrode device are connected, wherein the first electrode device is connected via the first connection portion of the graphite electrode and has a space capable of housing the second connection portion.

[0018] Such electrodes have space in the electrode device to accommodate the second connection portion of the graphite electrode, allowing for the connection of a graphite electrode with a second connection portion without any problems and enabling arc discharge.

[0019] Furthermore, the present invention provides a method for manufacturing a quartz glass crucible using any of the above-described graphite electrodes, comprising the steps of: connecting the graphite electrode to the first electrode device via the first connection part to constitute a first electrode; manufacturing a quartz glass crucible by arc discharge using the first electrode; removing the graphite electrode consumed by arc discharge using the first electrode from the first electrode device; connecting the graphite electrode removed from the first electrode device to the second electrode device via the second connection part to constitute a second electrode; and manufacturing one or more quartz glass crucibles by arc discharge using the second electrode.

[0020] The graphite electrode of the present invention has a second connection portion smaller than the first connection portion as described above. After connecting the first connection portion to the first electrode device and performing arc discharge to consume it, the second connection portion can be connected to the second electrode device and arc discharge can be performed again. Therefore, it is possible to manufacture a plurality of quartz glass crucibles by reusing one graphite electrode.

Effects of the Invention

[0021] Since the graphite electrode of the present invention has a second connection portion smaller than the first connection portion, after connecting the first connection portion to the first electrode device and performing arc discharge to consume it, the second connection portion can be connected to the second electrode device and arc discharge can be performed again. As a result, it is possible to manufacture a plurality of quartz glass crucibles by reusing one graphite electrode. Therefore, the electrode cost can be significantly reduced.

Brief Description of the Drawings

[0022] [Figure 1] FIG. 15 is a schematic diagram showing a first embodiment as an example of the graphite electrode, electrode device, and electrodes connected thereto of the present invention. [Figure 2] FIG. 18 is a schematic diagram showing a second embodiment as an example of the graphite electrode, electrode device, and electrodes connected thereto of the present invention. [Figure 3] FIG. 21 is a schematic diagram showing a third embodiment as an example of the graphite electrode, electrode device, and electrodes connected thereto of the present invention. [Figure 4] FIG. 24 is a schematic diagram showing a fourth embodiment as an example of the graphite electrode, electrode device, and electrodes connected thereto of the present invention. [Figure 5] FIG. 27 is a flowchart showing an example of a method for manufacturing a quartz glass crucible of the present invention. [Figure 6] FIG. 30 is a schematic diagram showing an example of a conventional graphite electrode, electrode device, and electrodes connected thereto. [Figure 7] FIG. 33 is a schematic diagram showing another example of a conventional graphite electrode, electrode device, and electrodes connected thereto.

Embodiments for Carrying Out the Invention

[0023] The present invention will be described in more detail below.

[0024] The graphite electrode of the present invention is a graphite electrode used for arc discharge in the manufacture of quartz glass crucibles, wherein the graphite electrode is equipped with a connector and connected to an electrode device for supplying current to the graphite electrode via the connector, the connector having a first connector and a second connector different from the first connector, the second connector being smaller than the first connector, the first connector having a shape that allows connection to a first electrode device, and the second connector having a shape that allows connection to a second electrode device which is smaller than the first electrode device. In this case, the first connector and the second connector can have a screw thread shape or a cylindrical shape.

[0025] Hereinafter, specific embodiments of the graphite electrode, electrode device, and electrode connected thereto of the present invention will be described by illustrating the first to fourth embodiments. In each embodiment, the same components will be denoted by the same reference numerals.

[0026] [First aspect] Figure 1 shows a first embodiment of the graphite electrode, electrode device, and electrode connected thereto according to the present invention. In this embodiment, the first connection part of the graphite electrode has a screw thread shape, and the second connection part has a cylindrical shape. In addition to the cylindrical shape, the second connection part can also be conical or polygonal prism shape, but a cylindrical shape is preferred in terms of manufacturing cost, mechanical strength, and connection strength.

[0027] The graphite electrode 11 shown in Figure 1(a) comprises a graphite electrode body 12 with a first connection part 14 and a second connection part 16 adjacent to the first connection part 14. These first connection part 14 and second connection part 16 are connected to an electrode device (the first electrode device 51 in Figure 1(b) and the second electrode device 71 in Figure 1(e), which will be described later) for supplying current to the graphite electrode 11. Also, as shown in Figure 1(a), the second connection part 16 is smaller than the first connection part 14.

[0028] Furthermore, the first connecting portion 14 has a shape that allows it to be connected to the first electrode device 51. In the first embodiment, as shown in Figure 1(a), the first connecting portion 14 has screw threads. On the other hand, the first electrode device 51 shown in Figure 1(b) has a female screw-shaped concave connecting portion 54 formed thereon. The graphite electrode 11 and the first electrode device 51 can be connected by screwing the first connecting portion 14 and the concave connecting portion 54 together, as shown in Figure 1(c).

[0029] Furthermore, the first electrode device 51 may have a space 56 capable of accommodating the second connection portion 16 of the graphite electrode 11, as shown in Figure 1(b). As shown in Figure 1(c), when the first electrode device 51 is connected via the first connection portion 14 using the recessed coupling portion 54, the second connection portion 16 of the graphite electrode 11 can be accommodated inside the space 56. Therefore, it is preferable that the space 56 be formed to be slightly larger than the second connection portion 16 of the graphite electrode 11.

[0030] As described above, the electrode (first electrode) 17 shown in Figure 1(c) is a connection between the graphite electrode 11 and the first electrode device 51. The first electrode device 51 is connected via the first connection part 14 of the graphite electrode 11 and has a space 56 capable of housing the second connection part 16. Using such an electrode (first electrode) 17, arc discharge can be performed to manufacture a quartz glass crucible. After arc discharge, the size of the graphite electrode body 12 decreases due to wear. Figure 1(d) shows the graphite electrode body 12a after it has been reduced in size. Although not shown in Figure 1(d), the shape of the graphite electrode body 12a may also change as it decreases in size.

[0031] Furthermore, the second connection portion 16 of the graphite electrode 11 has a shape that allows it to be connected to a second electrode device 71 which is smaller than the first electrode device 51, as shown in Figure 1(e). In the first embodiment, as shown in Figures 1(a) and (d), the second connection portion 16 has a cylindrical shape. Also, the second electrode device 71 shown in Figure 1(e) has a recessed coupling portion 76 into which the second connection portion 16 can be inserted. The graphite electrode 11 and the second electrode device 71 can be connected by connecting the second connection portion 16 and the recessed coupling portion 76, as shown in Figure 1(f). Using the second electrode 18 formed by connecting the graphite electrode 11 and the second electrode device 71, an arc discharge can be performed to manufacture a quartz glass crucible.

[0032] As described above, typically, the embedded method of connecting graphite electrodes to electrode devices is used for relatively small graphite electrodes, while the screw-in method of connecting graphite electrodes to electrode devices is used for relatively large graphite electrodes. Therefore, the first embodiment, in which the first connection part of the graphite electrode has a screw thread shape and the second connection part has a cylindrical shape, is preferable, but the second to fourth embodiments described below can also be adopted.

[0033] [Second aspect] Figure 2 shows a second embodiment of the graphite electrode, electrode device, and electrode connected thereto according to the present invention. In this embodiment, both the first and second connection portions of the graphite electrode have a screw thread shape.

[0034] The graphite electrode 21 shown in Figure 2(a) comprises a graphite electrode body 22 with a first connection portion 24 and a second connection portion 26 adjacent to the first connection portion 24. These first connection portion 24 and second connection portion 26 are connected to an electrode device (the first electrode device 51 in Figure 2(b) and the second electrode device 81 in Figure 2(e), which will be described later) for supplying current to the graphite electrode 21. As shown in Figure 2(a), the second connection portion 26 is smaller than the first connection portion 24.

[0035] Furthermore, the first connection portion 24 has a shape that allows it to be connected to the first electrode device 51. In the second embodiment, as shown in Figure 2(a), the first connection portion 24 has screw threads. The first electrode device 51 shown in Figure 2(b) is the same as the one shown in Figure 1(b) in the first embodiment, and has a female screw-shaped concave connection portion 54. The graphite electrode 21 and the first electrode device 51 can be connected by screwing the first connection portion 24 and the concave connection portion 54 together, as shown in Figure 2(c).

[0036] Furthermore, the first electrode device 51 may have a space 56 capable of accommodating the second connection portion 26 of the graphite electrode 21, as shown in Figure 2(b). As shown in Figure 2(c), when the first electrode device 51 is connected via the first connection portion 24 using the concave coupling portion 54, the second connection portion 26 of the graphite electrode 21 can be accommodated inside the space 56. For this reason, it is preferable that the space 56 be formed to be slightly larger than the second connection portion 26 of the graphite electrode 21. Also, even if the shape of the second connection portion 26 has screw threads, it is preferable from the standpoint of manufacturing cost and other factors that the space 56 be a simple shape, such as a cylindrical shape.

[0037] As described above, the electrode (first electrode) 27 shown in Figure 2(c) is a connection between the graphite electrode 21 and the first electrode device 51. The first electrode device 51 is connected via the first connection part 24 of the graphite electrode 21 and has a space 56 that can accommodate the second connection part 26. Using such an electrode (first electrode) 27, arc discharge can be performed to manufacture a quartz glass crucible. After arc discharge, the size of the graphite electrode body 22 decreases due to wear. Figure 2(d) shows the graphite electrode body 22a after it has been reduced in size. Although not shown in Figure 2(d), the shape of the graphite electrode body 22a may also change as it decreases in size.

[0038] Furthermore, the second connection portion 26 of the graphite electrode 21 has a shape that allows connection to a second electrode device 81 which is smaller than the first electrode device 51, as shown in Figure 2(e). In the second embodiment, as shown in Figures 2(a) and (d), the second connection portion 26 also has screw threads, similar to the first connection portion 24. The second electrode device 81 shown in Figure 2(e) has a female screw-shaped concave connection portion 86 formed therein so that the second connection portion 26 can be connected. The graphite electrode 21 and the second electrode device 81 can be connected by screwing the second connection portion 26 and the concave connection portion 86 together, as shown in Figure 2(f). Using the second electrode 28, which is formed by connecting the graphite electrode 21 and the second electrode device 81, an arc discharge can be performed to manufacture a quartz glass crucible.

[0039] [Third aspect] Figure 3 shows a third embodiment of the graphite electrode, electrode device, and electrode connected thereto according to the present invention. In this embodiment, both the first and second connection parts of the graphite electrode have a cylindrical shape. The first and second connection parts can also be conical, frustoconical, polygonal prism, etc., but a cylindrical shape is preferred in terms of manufacturing cost, mechanical strength, and connection strength.

[0040] The graphite electrode 31 shown in Figure 3(a) has a graphite electrode body 32 equipped with a first connection part 34 and a second connection part 36 adjacent to the first connection part 34. These first connection part 34 and second connection part 36 are connected to an electrode device (the first electrode device 61 in Figure 3(b) and the second electrode device 71 in Figure 3(e), which will be described later) for supplying current to the graphite electrode 31. Also, as shown in Figure 3(a), the second connection part 36 is smaller than the first connection part 34.

[0041] Furthermore, the first connecting portion 34 has a shape that allows it to be connected to the first electrode device 61. In the third embodiment, as shown in Figure 3(a), the first connecting portion 34 is cylindrical. On the other hand, the first electrode device 61 shown in Figure 3(b) has a recessed connecting portion 64 formed therein that allows the cylindrical first connecting portion 34 to be driven in (i.e., cylindrical in shape). The graphite electrode 31 and the first electrode device 61 can be connected by driving in or other means, as shown in Figure 3(c).

[0042] Furthermore, the first electrode device 61 may have a space 66 capable of accommodating the second connection portion 36 of the graphite electrode 31, as shown in Figure 3(b). As shown in Figure 3(c), when the first electrode device 61 is connected via the first connection portion 34 using the recessed coupling portion 64, the second connection portion 36 of the graphite electrode 31 can be accommodated inside the space 66. For this reason, it is preferable to form the space 66 to be slightly larger than the second connection portion 36 of the graphite electrode 31.

[0043] As described above, the electrode (first electrode) 37 shown in Figure 3(c) is a connection between the graphite electrode 31 and the first electrode device 61. The first electrode device 61 is connected via the first connection part 34 of the graphite electrode 31 and has a space 66 capable of housing the second connection part 36. Using such an electrode (first electrode) 37, arc discharge can be performed to manufacture a quartz glass crucible. After arc discharge, the size of the graphite electrode body 32 decreases due to wear. Figure 3(d) shows the graphite electrode body 32a after it has been reduced in size. Although not shown in Figure 3(d), the shape of the graphite electrode body 32a may also change as it decreases in size.

[0044] Furthermore, the second connection portion 36 of the graphite electrode 31 has a shape that allows it to be connected to a second electrode device 71 which is smaller than the first electrode device 61, as shown in Figure 3(e). In the third embodiment, as shown in Figures 3(a) and (d), the second connection portion 36 has a cylindrical shape. Also, the second electrode device 71 shown in Figure 3(e) has a recessed coupling portion 76 into which the second connection portion 36 can be inserted. The graphite electrode 31 and the second electrode device 71 can be connected by connecting the second connection portion 36 and the recessed coupling portion 76, as shown in Figure 3(f). Using the second electrode 38, which is formed by connecting the graphite electrode 31 and the second electrode device 71, an arc discharge can be performed to manufacture a quartz glass crucible.

[0045] [Fourth aspect] Figure 4 shows a fourth embodiment of the graphite electrode, electrode device, and electrode connected thereto according to the present invention. In this embodiment, the first connection part of the graphite electrode has a cylindrical shape, and the second connection part has a screw thread shape. In addition to the cylindrical shape, the first connection part can also be a frustoconical shape or a polygonal prism shape, but a cylindrical shape is preferred in terms of manufacturing cost, mechanical strength, and connection strength.

[0046] The graphite electrode 41 shown in Figure 4(a) has a graphite electrode body 42 equipped with a first connection part 44 and a second connection part 46 adjacent to the first connection part 44. These first connection part 44 and second connection part 46 are connected to an electrode device (the first electrode device 61 in Figure 4(b) and the second electrode device 81 in Figure 4(e), which will be described later) for supplying current to the graphite electrode 41. Also, as shown in Figure 4(a), the second connection part 46 is smaller than the first connection part 44.

[0047] Furthermore, the first connecting portion 44 has a shape that allows it to be connected to the first electrode device 61. In the fourth embodiment, as shown in Figure 4(a), the first connecting portion 44 has a cylindrical shape. The first electrode device 61 shown in Figure 4(b) is the same as the one shown in Figure 3(b) in the third embodiment, and has a concave connecting portion 64 that is shaped (i.e., cylindrical) into which the cylindrical first connecting portion 44 can be driven. The graphite electrode 41 and the first electrode device 61 can be connected by driving the first connecting portion 44 and the concave connecting portion 64 together, as shown in Figure 4(c).

[0048] Furthermore, the first electrode device 61 may have a space 66 capable of accommodating the second connection portion 46 of the graphite electrode 41, as shown in Figure 4(b). As shown in Figure 4(c), when the first electrode device 61 is connected via the first connection portion 44 using the concave coupling portion 64, the second connection portion 46 of the graphite electrode 41 can be accommodated inside the space 66. For this reason, it is preferable that the space 66 be formed to be slightly larger than the second connection portion 46 of the graphite electrode 41. Also, even if the shape of the second connection portion 46 has screw threads, it is preferable from the standpoint of manufacturing cost and other factors that the space 66 be a simple shape, such as a cylindrical shape.

[0049] As described above, the electrode (first electrode) 47 shown in Figure 4(c) is a connection between the graphite electrode 41 and the first electrode device 61. The first electrode device 61 is connected via the first connection part 44 of the graphite electrode 41 and has a space 66 capable of housing the second connection part 46. Using such an electrode (first electrode) 47, arc discharge can be performed to manufacture a quartz glass crucible. After arc discharge, the size of the graphite electrode body 42 decreases due to wear. Figure 4(d) shows the graphite electrode body 42a after it has been reduced in size. Although not shown in Figure 4(d), the shape of the graphite electrode body 42a may also change as it decreases in size.

[0050] Furthermore, the second connection portion 46 of the graphite electrode 41 has a shape that allows connection to a second electrode device 81 which is smaller than the first electrode device 61, as shown in Figure 4(e). In the fourth embodiment, as shown in Figures 4(a) and (d), the second connection portion 46 has screw threads. Also, the second electrode device 81 shown in Figure 4(e) has a female screw-shaped concave connection portion 86 formed therein, similar to that in Figure 2(e) of the second embodiment, so that the second connection portion 46 can be connected to it. The graphite electrode 41 and the second electrode device 81 can be connected by screwing the second connection portion 46 and the concave connection portion 86 together, as shown in Figure 4(f). Using the second electrode 48, which is formed by connecting the graphite electrode 41 and the second electrode device 81, an arc discharge can be performed to manufacture a quartz glass crucible.

[0051] Next, the method for manufacturing a quartz glass crucible using the graphite electrode of the present invention will be described in more detail. A flowchart of this method is shown in Figure 5. The following description will be based on the first embodiment shown in Figure 1, but the method is similar when using the graphite electrodes of the second to fourth embodiments, except that the combination of screw-in and drive-in connection methods differs.

[0052] First, the graphite electrode 11 shown in Figure 1(a) is connected to the first electrode device 51 shown in Figure 1(b) via the first connection part 14 to form the first electrode 17 (Figure 1(c), step S11 in Figure 5). The connection here is made by screwing, as shown in Figure 1(c). At this time, the second connection part 16 of the graphite electrode 11 is housed in the space 56 of the first electrode device 51.

[0053] Next, a quartz glass crucible is manufactured by arc discharge using the first electrode 17 (step S12 in Figure 5). The specific method for manufacturing the quartz glass crucible here is not particularly limited; the graphite electrode and electrode of the present invention can be used for manufacturing a quartz glass crucible using a graphite electrode.

[0054] Next, the graphite electrode 11, which has been worn down by the arc discharge using the first electrode 11, is removed from the first electrode device 51 (step S13 in Figure 5). At this time, as shown in Figure 1(d), the graphite electrode body 12a of the first graphite electrode 11 has been worn down and its size has decreased. In addition, the shape of the graphite electrode body 12a may have changed from that of the graphite electrode body 12 before wear due to wear.

[0055] Next, the removed graphite electrode 11 is connected to the second electrode device 71, but before that, the graphite electrode 11 may be cleaned as appropriate. Also, any deposits such as silica fine particles attached to the surface of the graphite electrode body 12a may be removed. Furthermore, if deformation of the graphite electrode body 12a is a problem, processing such as grinding the surface may be performed.

[0056] Next, the graphite electrode 11 removed from the first electrode device 51, as shown in Figure 1(d), is connected to the second electrode device 71, as shown in Figure 1(e), via the second connection part 16 to form the second electrode 18 (Figure 1(f), step S14 in Figure 5). The connection here is made by the implantation method, as shown in Figure 1(f).

[0057] Next, one or more quartz glass crucibles are manufactured by arc discharge using the second electrode 18 (step S15 in Figure 5). After manufacturing one quartz glass crucible, if there are no problems such as minimal wear on the graphite electrode 11, the graphite electrode 11 can be used as is to manufacture the next quartz glass crucible, thereby manufacturing multiple quartz glass crucibles. In this case, the diameter of the quartz glass crucible manufactured using the second electrode 18 can be smaller than the diameter of the quartz glass crucible manufactured using the first electrode 17.

[0058] Thus, since the graphite electrode of the present invention can be connected to different electrode devices and each can perform arc discharge, it is possible to manufacture multiple quartz glass crucibles by reusing a single graphite electrode. [Examples]

[0059] The present invention will be described in more detail below with reference to embodiments, but the present invention is not limited to these embodiments, and various modifications are possible as long as they do not deviate from the technical concept of the present invention.

[0060] (Examples) A quartz glass crucible was manufactured using the graphite electrode 11 of the first embodiment of the present invention shown in Figure 1, following the flow shown in Figure 5.

[0061] First, a graphite electrode 11 was prepared as shown in Figure 1(a). The graphite electrode body 12 was cylindrical in shape with a diameter of 80 mm and a length of 300 mm, with a first connection part 14 having screw threads and a second connection part 16 being cylindrical (a projection called a nipple). The second connection part 16 was made smaller than the first connection part 14, as shown in Figure 1(a).

[0062] Furthermore, a first electrode device 51 as shown in Figure 1(b) was prepared. This first electrode device 51 has a female screw-shaped concave coupling portion 54 and a space 56 adjacent to the concave coupling portion 54.

[0063] Next, as shown in Figure 1(c), the graphite electrode 11 was connected to the first electrode device 51 by screwing it in via the first connection part 14 and the recessed coupling part 54 to form the first electrode 17 (step S11 in Figure 5).

[0064] Next, a quartz glass crucible (800 mm diameter, 32 inches) was manufactured by arc discharge using the first electrode 17 (step S12 in Figure 5).

[0065] Next, the graphite electrode 11, which had been worn down by the arc discharge, was removed from the first electrode device 51 (step S13 in Figure 5). After the arc discharge, the size of the graphite electrode body 12a decreased due to wear, as shown in Figure 1(d). The size of the graphite electrode body 12a was approximately 60 mm in diameter and 200 mm in height.

[0066] The removed graphite electrode 11 was too small to use in the first electrode device 51, so it was decided to use it in the second electrode device 71. The removed graphite electrode 11 was cleaned to remove any attached substances.

[0067] Next, the graphite electrode 11 was connected to the second electrode device 71 as shown in Figure 1(e) via a second connection part 16 and a recessed coupling part 76 using a pressing method to form a second electrode 18 as shown in Figure 1(f) (step S14 in Figure 5).

[0068] Next, a quartz glass crucible (600 mm diameter, 24 inches) was manufactured by arc discharge using the second electrode 18 (step S15 in Figure 5).

[0069] In this way, one graphite electrode 11 could be connected to a different electrode device than the initial electrode device and reused in the manufacture of a quartz glass crucible.

[0070] It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are merely illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention. [Explanation of Symbols]

[0071] 11, 21, 31, 41... Graphite electrodes, 12, 22, 32, 42... Graphite electrode body, 12a, 22a, 32a, 42a... Used graphite electrode body, 14, 24, 34, 44... First connection point, 16, 26, 36, 46... Second connection point, 17, 27, 37, 47...the first electrode, 18, 28, 38, 48... Second electrode, 51, 61... First electrode device, 54, 64... Concave coupling portion of the first electrode device, 56, 66...Spaces capable of housing the second connection point of the graphite electrode, 71, 81... Second electrode device, 76, 86... Concave coupling portion of the second electrode device.

Claims

1. A graphite electrode used in arc discharge for manufacturing quartz glass crucibles, The graphite electrode is equipped with a connecting portion and is connected via the connecting portion to an electrode device for supplying current to the graphite electrode. The aforementioned connection portion has a first connection portion and a second connection portion that is different from the first connection portion. The second connection part is smaller than the first connection part. The first connection portion has a shape that allows it to be connected to the first electrode device. The graphite electrode is characterized in that the second connection portion has a shape that allows it to be connected to a second electrode device which is smaller than the first electrode device.

2. The graphite electrode according to claim 1, characterized in that the first connecting portion and the second connecting portion have a screw thread shape or a cylindrical shape.

3. An electrode in which the graphite electrode according to claim 1 or claim 2 is connected to the first electrode device, The electrode is characterized in that the first electrode device is connected to the graphite electrode via the first connection portion and has a space capable of housing the second connection portion.

4. A method for manufacturing a quartz glass crucible using a graphite electrode according to claim 1 or claim 2, The steps include: connecting the graphite electrode to the first electrode device via the first connection part to constitute the first electrode; A step of manufacturing a quartz glass crucible by arc discharge using the first electrode, The steps include removing the graphite electrode, which has been consumed by arc discharge using the first electrode, from the first electrode device, The steps include: connecting the graphite electrode removed from the first electrode device to the second electrode device via the second connection part to constitute a second electrode; The steps include manufacturing one or more quartz glass crucibles by arc discharge using the second electrode, and A method for manufacturing a quartz glass crucible, characterized by having the following features.

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