JP4092722B2 - Quartz crucible manufacturing furnace - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for producing a quartz glass crucible used for pulling a silicon single crystal. More specifically, the present invention relates to a heating furnace for manufacturing a quartz glass crucible that can manufacture a high-purity quartz crucible that has a high degree of sealing and is easy to control the temperature and environment in the heating chamber, and that prevents contamination and foreign matter from entering as much as possible. .
[0002]
[Prior art]
As a technique for producing the quartz glass crucible, a rotary mold method is known. In this method, quartz powder is deposited on the inner surface of a rotating bowl-shaped mold, and the quartz powder is heated and melted by virtue of arc heating or the like to be vitrified, cooled, and then extracted from the mold. In the conventional manufacturing apparatus based on this method, the turntable on which the mold is placed and the electrode means for arc heating are often provided in a normal room that is open, and few of them form a clean room. For this reason, there exists a problem that the surrounding dust tends to mix in molten glass at the time of heat-melting, and the purity of a crucible falls. Moreover, in the conventional manufacturing apparatus, although the door etc. which shield arc discharge from the circumference | surroundings are provided, since the support structure of the electrode etc. is formed as it is exposed above the crucible, foreign matter enters the mold from here. There is a possibility that the quartz glass crucible may be contaminated, or there is a problem that the silicon dioxide compound floating above adheres to the support structure of the electrode and causes trouble in maintenance.
[0003]
[Problem to be Solved by the Invention]
The present invention solves the above-mentioned problems in the conventional manufacturing apparatus, and provides a heating furnace capable of manufacturing a high-purity quartz glass crucible while effectively preventing the introduction and contamination of foreign substances from the outside. .
[0004]
[Means for solving the problems]
The heating furnace of the present invention is (1) an apparatus for producing a quartz crucible by heating and melting quartz powder based on a rotating mold method, and an electrode provided with a rotating table on which a mold is placed and an electrode rod for arc heating the quartz powder. A quartz crucible for producing a quartz crucible, comprising a structure portion and a heating chamber, wherein an electrode rod projects toward a turntable of the heating chamber, and a support means for the electrode rod is installed outside the heating chamber It is a heating furnace. As described above, the heating furnace of the present invention accommodates only minimum means such as a mold turntable and an electrode rod in the heating chamber, and these drive mechanisms are provided outside the chamber, so that the heating chamber is hermetically sealed during melting. Thus, it is possible to effectively prevent foreign matters from being mixed in and contaminated. Therefore, the cleanliness in the heating chamber can be increased and a clean environment much higher than that of conventional manufacturing equipment can be maintained, so that a high-purity quartz glass crucible can be obtained. The electrode structure provided on the upper side of the heating chamber ceiling is a portion provided with electrode support means, electrode bar opening / closing means attached as necessary, and energization means (including these support means). .
[0005]
In the heating furnace of the present invention, preferably, (2) the heating chamber can be sealed and an intake duct and an exhaust duct for clean air are provided in the heating chamber. This is a heating furnace in which particles having a diameter of 0.5 μm or more are maintained at a cleanliness of 100,000 pieces / cf or less. As described above, the heating furnace of the present invention closes the heating chamber door during operation and seals the inside of the heating chamber, and introduces clean air into the room through the intake duct. Particles having a particle size of 0.5 μm or more can be maintained at 100,000 / cf or less, preferably 10,000 / cf or less. More preferably, a means for reducing the pressure in the heating chamber is provided, and an air filter is provided in the intake duct to increase the cleanliness.
[0006]
The heating furnace of the present invention is preferably (3) a heating furnace in which an upward air flow is formed in the heating chamber by providing an intake duct in the lower portion of the heating chamber and an exhaust duct in the upper portion of the heating chamber, (4 ) A heating furnace in which the inlet and outlet of the heating chamber are provided symmetrically with respect to the mold rotation axis. During operation, an upward air flow along the inner surface of the mold is generated inside the mold due to arc discharge. Therefore, an upward air flow that is axially symmetric with respect to the mold rotation axis is formed in the heating chamber to smoothly exhaust the air around the mold. Can be done.
[0007]
In the heating furnace of the present invention, preferably, (5) a part of the ceiling of the heating chamber and a part of the side wall connected to a part of the ceiling are integrally separated from the heating chamber so as to be movable. The electrode structure is mounted on the movable ceiling part, and the electrode bar can be moved in and out of the heating chamber by the movement of the ceiling part and the electrode bar is housed in the heating chamber. It is a heating furnace in which the opening portions of the ceiling and side walls are closed. With such a structure, the electrode rod can be formed in and out of the heating chamber so that the ceiling and side walls of the heating chamber are shielded from the outside while the electrode rod is housed in the heating chamber. By closing the door of the entrance / exit, the heating chamber can be easily sealed.
[0008]
In the heating furnace of the present invention, preferably, (6) heating means in which electrode rod support means are provided outside the heating chamber ceiling, and a plurality of electrode rods are supported through the ceiling so as to be opened and closed downward. Furnace, (7) A heating furnace in which cooling means are provided in the electrode structure provided on the upper side of the heating chamber ceiling. In this way, the electrode structure is provided outside the ceiling, and the electrode rod is opened and closed by penetrating the ceiling downward, so that the electrode structure is cut off from the heating chamber. Can be effectively prevented. Incidentally, when the electrode rod support means is exposed above the crucible as in the conventional electrode structure, it is exposed to a high temperature of about 600 ° C. due to arc discharge, but it deteriorates at a high temperature. Such high temperature deterioration can be prevented by providing an electrode structure portion outside the room to block radiant heat and further providing a cooling means to the electrode structure portion. Further, the electrode rod can be opened and closed in accordance with the diameter of the crucible by an opening and closing mechanism provided in the electrode rod support means, and an optimum arc can be formed.
[0009]
Further, in the heating furnace of the present invention, preferably, (8) a turntable on which a mold is placed is disposed so as to protrude into the heating chamber, and the turntable is rotated and moved up and down by a driving means provided under the floor of the heating chamber. It is a heating furnace. Thus, by providing the drive mechanism of the mold turntable outside the room, it is possible to effectively prevent foreign matters from being mixed in and contaminated from the outside.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be specifically described based on embodiments.
An outline of the heating furnace of the present invention is shown in FIG. This heating furnace is a quartz crucible manufacturing apparatus based on the rotary mold method, and heats and melts quartz powder deposited on the inner surface of the mold, or heats and melts quartz powder and deposits it on the inner surface of the mold to produce a quartz crucible. The illustrated heating furnace includes a heating chamber 10, and includes a rotating table 12 on which a mold 11 is placed and an electrode structure portion 13 including an electrode rod 14 for arc-heating quartz powder. The support means 15 is provided outside the ceiling of the heating chamber 10. Preferably, most of the ceiling wall or side wall of the heating chamber 10 is covered with a water cooling jacket.
[0011]
In the illustrated heating furnace, a part of the ceiling (top plate) 16 of the heating chamber and a part of the side wall (side plate) 18 connected to a part of the ceiling are integrally separated from the heating chamber so as to be movable. ing. Specifically, the guide rail 17 extends from the ceiling of the heating chamber 10 to the side, and the top plate 16 is slidably supported by the guide rail 17. Support means 15 for the electrode rod 14 is mounted on the top plate 16. The support means 15 is provided with cooling means (not shown). A part of the side wall (side plate) 18 connected to the top plate 16 is formed integrally with the top plate 16 so as to slide sideways along the guide rail 17.
[0012]
As described above, since the electrode structure 13 is provided on the slidable top plate, the electrode rod 14 is formed so as to be able to enter and leave the heating chamber. When the top plate 16 and the side plate 18 are separated from the heating chamber 10, a part of the ceiling and the side wall of the heating chamber 10 is opened, but the top plate 16 and the side plate 18 are integrally formed along the guide rail 17. When it moves to the heating chamber 10 and the electrode rod 14 is accommodated in the heating chamber 10, the top plate 16 closes the heating chamber ceiling and the side plate 18 seals the heating furnace side wall. Therefore, if the doorway 19 at the front of the heating chamber is closed by the door 20, the room can be easily sealed in a practical manner.
[0013]
On the other hand, a turntable 12 that supports the mold 11 is installed inside the heating chamber 10 so as to protrude into the room, and the turntable is rotated and moved up and down by driving means (not shown) provided under the floor. It is formed as follows. When the mold 11 containing quartz powder is placed on the turntable 12 by an external carry-in means, the turntable 12 is raised to a predetermined height by the driving means under the floor and is simultaneously rotated. Corresponding to this, arc discharge starts in a substantially sealed room, and the quartz powder deposited on the inner surface of the mold is heated and melted to be vitrified.
[0014]
Further, in the illustrated heating furnace, an intake duct 21 and an exhaust duct 22 for clean air are provided in communication with the heating chamber. Clean air can be introduced into the sealed heating chamber through the intake duct 21 to maintain the cleanliness of particles having a particle size of 0.5 μm or more of 100,000 / cf or less, preferably 10,000 / cf or less. Incidentally, the cleanliness in the conventional quartz crucible manufacturing furnace is about 500,000 to 1 million particles / cf of particles of 0.5 μm or more, and the heating furnace of the present invention is much higher than the conventional heating furnace. Cleanliness can be achieved. The heating chamber may be provided with means for reducing the pressure inside the chamber (not shown), and the intake duct 21 may be further provided with an air filter (not shown) to further increase the cleanliness.
[0015]
The intake duct 21 is provided in the lower part of the heating chamber, and the exhaust duct 22 is provided in the upper part of the heating chamber. Further, a plurality of intake ports of the intake duct 21 and exhaust ports of the exhaust duct 22 are provided. These intake ports 21a and exhaust ports 22a are respectively connected to the rotating shaft 30 of the mold as shown in FIG. Are provided symmetrically about the axis. By forming such an upward air flow in the heating chamber so as to be axisymmetric with respect to the mold rotation axis, it is possible to smoothly exhaust the air around the mold.
[0016]
【The invention's effect】
Since the hermetic heating furnace of the present invention has the above-described structure, the hermetic degree in the heating chamber is high, and the indoor cleanliness can be improved by effectively preventing contamination from outside and mixing of foreign substances. Therefore, it is suitable for producing a high-purity quartz glass crucible. In addition, since the volume in the heating chamber is smaller than that of an open-type manufacturing apparatus, it is easy to control the furnace temperature, and a high-quality quartz glass crucible can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view of a heating furnace of the present invention. FIG. 2 is an explanatory view showing intake and exhaust ports of the heating furnace of the present invention. 10—heating chamber, 11-mold, 12-rotary table, 13-electrode structure, 14-electrode rod, 15-support means, 16-top plate, 17-guide rail, 18-side plate, 19-entrance / exit, 20-door, 21-intake duct, 21a-intake port, 22-exhaust duct, 22a-exhaust mouth.

Claims (8)

An apparatus for producing a quartz crucible by heating and melting quartz powder based on the rotating mold method, having a rotating table on which a mold is placed, an electrode structure unit having an electrode rod for arc-heating quartz powder, and a heating chamber, A heating furnace for producing a quartz crucible, wherein an electrode rod protrudes toward a turntable of a heating chamber, and a support means for the electrode rod is installed outside the heating chamber. The heating chamber can be sealed and an intake duct and an exhaust duct for clean air are provided in the heating chamber, and clean air is introduced into the room, and 100,000 particles / cf. The heating furnace of Claim 1 maintained at the following cleanliness. The heating furnace according to claim 1 or 2, wherein an upward air flow is formed in the heating chamber by providing an intake duct at a lower portion of the heating chamber and an exhaust duct at an upper portion of the heating chamber. The heating furnace according to claim 2 or 3, wherein the intake port and the exhaust port of the heating chamber are provided symmetrically with respect to the mold rotation axis. A part of the ceiling of the heating chamber and a part of the side wall connected to the part of the ceiling are formed so as to be movable separately from the heating chamber, and the electrode structure part is mounted on the movable ceiling part. And the opening of the heating chamber and the side wall is closed while the electrode rod can be moved in and out of the heating chamber by the movement of the ceiling portion and the electrode rod is housed in the heating chamber. The heating furnace in any one of Claims 1-4. The heating furnace according to any one of claims 1 to 5, wherein a support means for the electrode rod is provided outside the ceiling of the heating chamber, and the plurality of electrode rods are supported so as to be openable and closable downward through the ceiling. . The heating furnace according to any one of claims 1 to 6, wherein a cooling means is provided on a support means of the electrode rod provided on the upper side of the heating chamber ceiling. The heating device according to any one of claims 1 to 7, wherein a turntable on which the mold is placed is slidably installed in the heating chamber, and the turntable is rotated and moved up and down by driving means provided under the floor of the heating chamber. Furnace.

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