JPH0812355A - Apparatus for producing quartz glass article - Google Patents

Abstract

PURPOSE:To efficiently obtain a molding having a projection by arranging a quartz glass body between a female mold and receiving base made of porous graphite and subjecting this body to press forming at a high temp. in a molding flask made of compact graphite by a specific method. CONSTITUTION:The female mold made of the porous graphite corresponding to the projection iis arranged on a back surface side and the receiving base made of the porous graphite on an upper surface side so as to sandwich the quartz glass body in the forming space having a graphite flask 7 formed of the deuse graphite material at the circumference. The receiving base is fixed and supported on the upper surface side by a fixing press rod 19 and the molding flask 7 forming is placed on a work table 3a. The quartz glass body is heated to a high temp. by a graphite heater 2 and a hydraulic cylinder 5 is actuated to rise a work table 3a into a furnace from a lower position outside the furnace via a movable press rod 3. The quartz glass body is thus press formed under high-temp. heating and the quartz glass articles having the projection on the plane side are produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of a quartz glass article in which protrusions are formed on at least one surface of a quartz glass body, and in particular, a quartz glass member used in the semiconductor industry. , Protrusions, fitting portions, or the like, which are often used for flange parts of furnace core tubes, top and bottom plates of vertical wafer carriers, side plates of horizontal wafer carriers, quartz glass jigs such as furnace core tube caps, and parts thereof. The present invention relates to an invention for efficiently producing a quartz glass article having a flange portion and the like.

[0002]

2. Description of the Related Art Conventionally, in the case of manufacturing a quartz glass member having such a complicated shape, a welding rod of quartz glass is heated by a burner heating on a quartz glass flat plate to successively build up while melting and melting, and then a built-up portion. Was manufactured by grinding and shaping it into a predetermined shape, or shaving from a quartz block body. However, work time is extremely long in overlay processing with a welding rod, and bubbles are caught if the welding speed and heating temperature are not adjusted properly. Since it is a fire processing, there was a problem that the working time was bad. In addition, there are problems in that the material consumption is large when the block material is machined, and that it takes a long time for the grinding.

In order to solve such a drawback, a heat molding method for heating and softening the quartz glass body in the molding die to form the protrusion is being studied. In this type of molding, for example, as shown in JP-A-1-317132, after heating the quartz glass base material to a high temperature of 1600 to 1800 ° C. in a molding container, a molding pressure is applied from both directions symmetrical to the base material. In addition, it is configured to perform pressure molding, but in such a molding method, for example, in the publication, the molding pressure is 100 Kgf / cm.
^The pressure is about ² and high, and when the molding is performed at such a high pressure, the graphite and the quartz glass constituting the molding frame adhere to each other at a high pressure at a high temperature. Therefore, the reaction between the graphite and the quartz glass causes CO, CO ₂ , and Generated SiO ₂ vaporized gas and entered these softened quartz glass to generate bubbles, and the SiC produced by the reaction adhered to the surface of the quartz glass and was cooled to room temperature. At this time, a crack is generated due to the difference in thermal expansion coefficient between the two.

For this reason, for example, Japanese Patent Publication No. 62-50414.
In No. 6, the inner surface of the molding frame is lined with a graphite chamber fiber cloth so that CO ₂ escapes from the fiber layer.
This technique, according to a practical example disclosed in the specification, was held at 1850 ± 5 ° C. for 30 minutes, and an inert gas N ^{2 was used.}
The pressure molding was successful at 0.4 km / cm ² in the atmosphere. This is because the lining graphite fiber cloth is SiO ²
The vapor gas such as effluent is prevented from being mixed into the product as air bubbles to improve the yield.

[0005]

However, in the structure in which the fiber layer is lined, when the raw ingot melts and comes into close contact with the cushion material of the side wall, the exhaust gas passage becomes only the pores of the side wall cushion material, and the bottom side. In the mechanism having a projection on the bottom as in the article according to the present invention, the retention of the gas at the bottom leads not only to a very serious defect, but also to the female recess corresponding to the projection. It is virtually impossible to lay the cushion material uniformly.

In order to prevent such defects, an apparatus for setting the heating temperature as low as 1600 ° C. to 1700 ° C. and using a molding hole having a through hole having a pore size of about 3 mm and molding without pressurization is disclosed in Japanese Patent Laid-Open No. Hei 10 (1999) -31868. It is proposed in No. 5-17174.

However, in such a mechanism, the heating temperature is 1
Since the viscosity is as low as 600 ° C. to 1700 ° C. and no pressure is applied, the molten glass does not sufficiently wrap around the projection portion of the flat surface in the case of the article according to the present invention, and thus accurate processing is also impossible. It will be possible.

In view of the above-mentioned conventional drawbacks, the present invention is capable of forming a quartz glass article having no protrusions with no devitrification or cracks on the surface even when a quartz glass article having a protrusion is processed, and can be molded with high precision. It is an object of the present invention to provide an invention for producing a glass article.

[0009]

SUMMARY OF THE INVENTION The present invention relates to an apparatus for producing a quartz glass article having a projection on its flat side by press-molding a quartz glass body under high temperature heating, and its features are as follows: In a molding space having a graphite frame in the periphery, a female die corresponding to the protrusion is arranged on the lower surface side with the quartz glass body sandwiched, and a pedestal for the glass body is arranged on the upper surface side, and the female die and the pedestal are arranged. A porous graphite material, on the one hand, the graphite frames are respectively formed of a dense graphite material to form a molding mold, and a support body for fixing and supporting the pedestal on the upper surface side; and a lower surface facing the support body on the one hand. A work table placed at a position for mounting the molding frame, an elevating means for moving the work table up and down from the outside of the furnace to the inside of the furnace, and a fluid pressure energizing unit provided under the work table. Step, and preferably the upper surface of the pedestal is fixed to the support by raising of the elevating means, and then high temperature heating is performed by urging the quartz glass body with a minute pressure force through the female mold by the fluid pressure urging means. It is characterized in that pressure molding is performed below.

In this case, the fluid pressure urging means is constituted by a hydraulic cylinder via a pressure detecting means, and the minute pressure applied by the pressure detecting means to the softened quartz glass body via the female die is 0.01. It is preferable to be configured to be controllable within the range of 0.5 Kgf / cm ² . Further, it is preferable that the glass body housed in the mold is capable of generating heat by induction heating means in order to enable rapid temperature rise.

Further, in order to facilitate continuous molding, an opening is formed below a furnace space surrounded by the heating element, and the work table can be opened and closed through two shutters so that the work table can enter the furnace. In addition to the above, it is preferable that, of the two shutters, the upper shutter facing the furnace space is made of a single-layer graphite material, and the lower shutter located at the lower side is made of a laminated graphite material. Further, in order to enable more accurate molding, detection means for detecting the amount of movement of the fluid pressure urging means is provided, and the temperature in the furnace is 1700 to 1700.
After reaching the temperature range of about 2000 ° C. and detecting the deformation completion position of the quartz glass body by the detection means, holding the molding completion position for a predetermined time, and then returning the female die through the fluid pressure urging means. It is better to lower in the direction.

In order to maintain the deformation completion position with high accuracy, the moving speed of the female die is set to 2 to 10 mm / min while moving the female die in the pressing direction by the hydraulic cylinder constituting the fluid pressure urging means. Good to set.

[0013]

In order to perform accurate heating as described above,
It is necessary to perform high temperature heating at around 1700 to 2000 ° C. However, when high temperature heating is performed, as described above, due to the reaction between graphite and quartz glass, CO and C
O ₂ and further SiO ₂ vaporized gas is generated, and bubbles of quartz glass are generated, and cracks and devitrification occur. Such measures are taken from both the molding frame and the molding pressure device.

First, the molding frame will be described. In a method of molding a quartz glass article by sandwiching a quartz glass body between a female die having a graphite frame surrounding it and a pedestal,
As shown in FIG. 4, a female die and a pedestal (these are referred to as push die) are always in contact with the quartz glass body during pressure molding.
Therefore, due to the reaction with quartz glass, CO and C
O ₂ and SiC vapor are generated only on the contact surface of the pressing die. Even if SiO ₂ vaporized gas is generated at the outer periphery of the glass body due to heating of the glass body, the quartz glass body is not in contact with the surrounding graphite frame until just before the completion of the molding, so that the gas is There is no need to consider the escape. Therefore, it is sufficient to provide the gas escape path only in the pair of pressing dies, but it is impossible to deform the former graphite fiber cloth according to the shape of the female projection.

On the other hand, as in the latter prior art, when the pores of about 3 mm are perforated, the silica glass has a high viscosity.
No problem occurs at 600-1700 ℃, but 1900 ℃
When the temperature is raised to, the viscosity of the quartz glass is significantly reduced, and the molded quartz glass article has irregularities on its surface.
Therefore, according to the present invention, the pressing die is formed by using porous graphite, such as sintered graphite, in which the graphite material itself has air permeability. That is, the value of this case is preferably a gas permeability 0.1cm ² /sec(P:1.5Kgf/cm ²⁾
As described above, a pressing die having a group of fine gas permeation holes of about 0.9 cm ² / sec is more preferably used.

A graphite material having a bulk density of 1.5 g / cm ³ or less may be used as the porous graphite material, but if the bulk density is too low, damage or deformation will occur during pressure molding. Therefore, 1.2 ± 0.
It is better to set it to 2 g / cm ³ . Further, in order to perform accurate molding without causing damage or deformation during pressure molding, the compressive strength is 100 Kgf / cm ² or more, preferably 150 to 6
It is necessary to set 00 Kgf / cm ² and a Shore hardness of 10 or more, preferably about 15 ± 2.

On the other hand, since the pressing die is always in contact with the quartz glass body during pressure molding, if impurities are present on the graphite side due to the contact, the semiconductor poison is proportionally produced on the surface of the quartz glass body. Also, a cristobalite layer is formed, which also causes devitrification and cracking. Therefore
It is preferable to set the metal poisons such as Na, K, Li, Ca, Mg, and Fe that cause the semiconductor poison and the cristobalite layer to 0.1 to 0.2 ppm or less.

On the other hand, in the vicinity of the completion of the molding of the quartz glass body, since the expansion output from the outer peripheral surface of the softened quartz glass body is urged to the inner wall surface of the graphite frame, the graphite frame is formed of a dense graphite material. However, it is necessary to make the bending strength several steps higher than the pressing die. Flexural strength towards the pressing mold in this case is 30kg / cm ² or more, preferably in the order may be set respectively for 50~300kg / cm ^2, bending strength of the graphite frame, more,
Specifically, it may be set to around 350 to 900 kg / cm ² . Therefore, the molding frame of the present invention is characterized in that the two types of graphite molds, that is, the female mold, the pedestal, and the graphite frame, have different compositions.

Next, the molding process will be examined. In this processing, as described above, the heating temperature is about 1700 to 2000 ° C,
Preferably, by setting it to 1840 to 1980 ° C,
Viscosity is low and molding can be facilitated. In this case, in the case of natural quartz glass produced by oxyhydrogen flame, the heating temperature is 18
About 40 to 1900 ° C, and in the case of natural quartz glass produced by the electric melting method, the heating temperature is set to about 1900 to 1960 ° C. In this case, the molding may be carried out without pressure, but if it is carried out without pressure, the pressing force changes due to the weight of the pressing die, which is not preferable. On the other hand, if the pressing force is set to a large value, the contact between the molding frame and the fused silica glass becomes too strong and the generation of reaction gas cannot be suppressed even if the molding frame is used. Therefore, in the present invention, the contact time and contact area between the molding frame and the fused silica glass in the high temperature heating region are set to be as small as possible. In addition, it is necessary to devise a device that can facilitate continuous molding.

Therefore, according to the present invention, there is provided a support body for fixedly supporting the pedestal on the upper surface side, a work table which is arranged at a lower position facing the support body and on which the molding frame is placed, and the work piece. A molding apparatus is proposed, which comprises an elevating means for elevating a table from the lower position outside the furnace to the inside of the furnace, and a fluid pressure urging means continuously provided under the work table.

That is, according to the present invention, after the upper surface of the pedestal is fixed to the support body by the elevation of the elevating means, a small pressure force is applied to the quartz glass body by the fluid pressure urging means via the female die, specifically, By performing pressure molding under high temperature heating while energizing a minute pressing force in the range of 0.01 to 0.5 Kgf / cm ² , preferably 0.02 to 0.2 Kgf / cm ² ,
It is possible to suppress the reaction by keeping the contact area between the quartz glass body and graphite as low as possible while maintaining accurate molding processing at a constant molding pressure. In this case, it is preferable to use a non-compressible hydraulic cylinder as the fluid pressure urging means, and particularly by constructing the hydraulic cylinder via the pressure detecting means, the pressing force can be maintained with high accuracy. Further, the minute pressing force applied to the quartz glass body through the female die by the fluid pressure urging means is pre-pressurized to the female die from a temperature range before the quartz glass body begins to be deformed, so that the degree of heating and softening is increased. Since it is gradually molded according to the above, it is possible to perform the molding process with high accuracy, which is preferable.

Further, according to the present invention, the structure is such that the work table arranged on the lower side pressurizes through the female die, and the female die is configured to directly bite into the softened quartz glass body. Therefore, it becomes possible to mold the projection with high accuracy. Further, since the pedestal on the upper side of the molding frame has a fixed pressure, it is sufficient to open only the lower side of the furnace where the work table moves up and down without opening the upper side of the furnace. As a result, with the conventional structure in which the upper part of the furnace is opened, the temperature inside the furnace decreases to near room temperature each time the inside of the furnace is opened, and the temperature rise time in the next molding process becomes extremely long. Since the atmosphere is left in the furnace, it is extremely advantageous as a device for continuous molding.

In this case, in order to facilitate continuous molding, the lower part of the furnace space surrounded by the heating element is opened, and two shutters are provided in the opening. The upper shutter facing the space is made of a single-layer graphite material with good heat insulation, and the lower shutter located at the lower side is made of, for example, a laminated graphite material that is alternately laminated with a quartz glass plate. The latter property can maintain the sealing property and strength. Further, the glass body is heated by the induction heating means so that the temperature can be quickly raised to the heating zone, and the molding time, in other words, the contact time between the molding frame and the fused silica glass is minimized. If the temperature rising rate is too fast, the temperature difference between the peripheral portion and the central portion of the glass body becomes large, and accurate molding cannot be performed. Therefore, in the present invention, the temperature rising rate of the glass body after heat-softening is 35 to 55 ° C / mi.
n, preferably 40 to 50 ° C./min.

The moving speed of the elevating means is to enable accurate molding even when the female projection has a complicated shape and without buckling, and to delay the molding time unnecessarily. , The moving speed of the elevating means is 2 to a slow speed.
It is set to 10 mm / min, preferably 3 to 5 mm / min. In this case, a detecting means for detecting the movement amount of the fluid pressure urging means is provided, and the temperature inside the furnace is 1700 to 20.
After reaching the temperature range of about 00 ° C. and detecting the deformation completion position of the quartz glass body by the detection means, the molding completion position is set to a predetermined time, specifically 3 to 15 depending on the projection shape.
It is preferable to hold for 5 minutes, preferably 5 to 10 minutes, and wait until the deformation of the quartz glass body is completed, and immediately after the completion of the molding, the female die is lowered in the returning direction via the fluid pressure urging means. By releasing the pressure by pressing, it is possible to prevent the reaction between the molding frame and the fused silica glass and prevent the protrusion during molding. A hydraulic cylinder is used as the fluid pressure urging means in order to maintain the deformation completion position with high accuracy and to enable accurate elevation control.

[0025]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are merely illustrative examples, without any intention of limiting the scope of the present invention thereto unless otherwise specified. Absent.

First, the molding frame used in this apparatus will be described.
FIG. 2 is an embodiment diagram showing the shape of the molding frame.
The structure of the molding frame for press-molding the side plate 51 of the horizontal boat 50 shown in FIG. 1 is disclosed. The female mold 13 has a recess 13a corresponding to the protrusion 51a of the side plate 51 of FIG. It is open to. That is, the main molding frame is shown in FIG.
As shown in FIG. 5, a concave portion 13C corresponding to the protrusion 51a with the quartz glass body 8 sandwiched between the quartz glass body 8 is formed in a rectangular graphite frame forming a molding space composed of a graphite frame 15 made of dense graphite and a bottom plate 12. Female mold 1
3 and the pedestal 10 are arranged so that the width between the pedestal 10 and the female die 13 can be reduced, and the outer shapes of the pedestal 10 and the female die 13 are slightly smaller than the inner shape of the rectangular graphite frame 15. It is set.

An arm-shaped relief portion 10a is provided at a predetermined position of the receiving base 10 corresponding to the concave portion 13a of the female die 13, and the relief portion 10a has a volume equal to or slightly larger than that of the concave portion 13a of the female die 13. Set to. And the female mold 13
The pedestal 10 is formed to be thick so as to withstand the compressive stress under the pressing load, and the graphite frame 15 is formed to be a thin rectangular frame so as to absorb heat well.

FIG. 3 is an embodiment showing another shape of the molding frame.
The quartz glass article of this example is provided with a protrusion 56 as shown in FIG. 7C and functions as, for example, a flange portion 56 of a vertical core tube 55. The recess 13a corresponding to the ring-shaped protrusion 56a is opened. As shown in (A), the main molding frame includes the quartz glass body 8 in a cylindrical graphite frame that forms a molding space 11 composed of a graphite cylinder 15 made of dense graphite and a bottom plate 12. The protrusion 1
The female die 13 having the concave portion 13c corresponding to 7c and the pedestal 10 are arranged, and the width between the pedestal 10 and the female die 13 can be reduced. The outer diameter of the female die 13 is set to be slightly small.

Further, the mandrel 16 has a central hole 56 in the flange 56.
Although it is planted in the female die 13 to provide d, the central hole 56d may be cut after the completion of molding, and is not always required.

[0030] Then the graphite making up the embodiments also female 13 and support 10 in any case, the gas permeability is 0.1 cm ² value of /sec(P:1.5Kgf/cm ²⁾ or more, preferably 0 It has a group of fine gas permeation holes of about 9.9 cm ² / sec, and has a bulk density of 1.5 g / cm ² or less, preferably 1.24 g / cm ² , and a compressive strength of 100 Kgf.
/ Cm ² or more, preferably about 160 Kgf / cm ² , a Shore hardness of 10 or more, preferably about 15 and a bending strength of 3
The resistance is set to 0 kg / cm ² or more, preferably about 69 kg / cm ² , and the specific resistance is set to 40 μΩ · cm.

The purity of the graphite is Na, K, Li,
Mg, Ca, Cu, Al 0.1ppm or less, Fe 0.15p
It is set to pm or less, and is manufactured at a higher purity than at least the purity of the quartz glass to be molded. The graphite material of the pedestal 10 and the female die 13 is formed by sintering or the like. In this case, the average particle diameter of graphite is 30 to 30.
The thickness is preferably set to 100 μm, preferably 40 to 100 μm.

On the other hand, the dense graphite forming the graphite frame 15 and the bottom plate 12 has a bulk density of 1.77 to.
1.90 g / cm ² , compressive strength 700 to 1050 kg
f / cm ² , Shore hardness of about 50 to 90, bending strength of 370 to 900 kg / cm ² , and specific resistance of 0.9 to 1.
Set to 8 μΩ · cm.

The protrusion 13b to be planted in the female die 13
Also, it is preferable that the mandrel 16 is also made of the same material as the female die 13, but it is not always in contact during the molding and heating, and is not necessarily limited.

Next, the basic structure of the molding apparatus using the molding frame will be described. FIG. 1 discloses a basic configuration diagram of a quartz glass article molding apparatus of the present invention. In FIG.
A graphite heater 2 that is open at the bottom and is heated by the electromagnetic induction action of an electromagnetic induction heating coil 2A disposed around the housing 1 is provided inside a graphite-made housing 1 having a gate-shaped cross section. 2, the induction heating coil 2A is power-controlled by the thermometer and other control devices shown in FIG. 6, and the room temperature is controlled to a set temperature. The movable press rod 3 having the work table 3a at the upper end is made of graphite, and the lower end is connected to the piston portion 5a of the hydraulic cylinder 5, and is vertically moved by driving the piston portion 5a via the load cell 3c. It is configured to be possible.

The molding frame 7 is placed on the work table 3a, and the molding frame 7 is pressed upward by the driving of the hydraulic cylinder 5, but the upper surface of the pedestal 10 located above the molding frame 7 is pushed. When the fixed press bar 19 comes into contact, the molding frame 7 is pressed in the vertical direction.
The fixed press bar 19 is made of graphite and is integrally fixed to the housing 1.

The load cell 3c arranged between the piston portion 5a of the hydraulic cylinder 5 and the movable press rod 3 is constructed so that the pressure during the pressing can be measured. A scale 4 is vertically installed on the side surface of the hydraulic cylinder 5, and the moving distance of the movable press rod 3 can be confirmed by a pointer 3b extending horizontally from the side face of the press rod 3. As a result, the amount of displacement of the movable press rod 3 against the molding frame 7 can be visually confirmed by observing the pointer 3b on the scale 4, and the completion of molding can be visually confirmed by confirming the rising position of the pointer 3b. .

Incidentally, this molding completion detection converts the moving amount of the pointer 3b into an electric signal such as a resistance change or a capacitor,
It is also possible to signal with a lamp or a buzzer. The lower entrance portion of the housing 1 is configured to be closed by a shutter 6, and the shutter 6 is made of heat-resistant carbon felt, and extends along the lower surface of the housing 1 by an air cylinder (not shown) or the like. It can be opened and closed. After the shutter 6 is closed, the inside of the housing 1 can be replaced with an inert gas such as N ² or Ar or He by a device (not shown). The movable press rod 3, the hydraulic cylinder 5, and the scale 4 are integrally movable up and down so that the movable press rod 3, the hydraulic cylinder 5, and the scale 4 can move in and out of the housing 1 by a ball screw or other elevating means 35 which will be described in detail later. After opening, the molding frame 7 can be replaced by lowering them through the elevating means 35 and pulling the work table 3a out of the housing 1.

Next, a hot press machine according to an embodiment of the present invention based on the above basic structure will be described with reference to FIG.
In the figure, the same reference numerals as those in FIG. 1 represent the same members.
Reference numeral 30 denotes a stainless steel molding furnace main body installed in a gate-shaped machine frame 34, in which a water cooling jacket (not shown) is wrapped around the outer peripheral side, while an opaque quartz tube 3 is provided on the inner wall side of the furnace main body 30.
An induction heating coil 2A is provided in a surrounding manner through 9,
On the inner peripheral side of the heating coil 2A, a furnace inner space 42 is formed, which is surrounded by a graphite heat insulating material 37 around the upper surface and the side wall and is open at the lower side.

A graphite heater 2 is disposed on the inner peripheral side of the side wall heat insulating material 37 and is induction-heated by high-frequency electromagnetic induction with the induction heating coil 2A. As described above, the heater 2 is configured to control the electric power of the induction heating coil 2A by the thermometer 33 outside the furnace and control the room temperature to the set temperature. On the axis of the heat insulating material 37 on the upper surface side, a fixed press rod 19 made of graphite hangs down toward the furnace space 42 side, and the upper portion of the press rod 19 is made of the heat insulating material 3.
7 is projected above. And the press rod 19 is a machine frame 3
Even if the work table 3a is fixed and the work table 3a is lifted to receive the hydraulic pressure through the pedestal 10, the fixed press rod 19 can always be held at a predetermined position.

On the other hand, below the work table 3a facing the fixed press bar 19 through the furnace space 42, the above-mentioned movable press bar 3 made of graphite, the water cooling rod 5a corresponding to the piston part of the hydraulic cylinder 5, and the Load cell 3
The hydraulic cylinders 5 are vertically connected via c, and these are connected to the nut portion 35a of the ball screw 35c via a holding frame 36.

The ball screw 35c is provided vertically along the vertical leg 34a of the machine frame 34 in parallel with the advancing / retreating direction of the hydraulic cylinder 5, and the motor 35b drives the ball screw 35c.
Is rotated to vertically move the hydraulic cylinder 5 via the nut portion 35a and the holding frame 36 that are screwed together.

The scale 4 is vertically attached to the side surface of the vertical leg 34a of the machine frame 34, the holding frame 36 is erected along the scale 4 in an L shape, and the scale 4 is erected on the erection portion 36a. Is provided with a pointer 3b that fits in the.

The shutter 6 is composed of an upper shutter 6A made of a graphite plate (single-layer graphite) and a lower shutter 6B formed by laminating a quartz glass plate and a graphite plate (laminated graphite), which are integrally formed with the air cylinder 32. Is configured so that it can move forward and backward along the horizontal direction. That is, the upper shutter 6A moves horizontally along the lower surface of the heat insulating material 38 so as to close the furnace space 50, while the lower shutter 6B horizontally moves along the lower surface of the furnace body 30 so as to close the furnace body 30. It is configured to be movable. The shutters 6A and 6B are both fitted around the axis of the movable press rod 3 so that the movable press rod 3 can move up and down even after the shutter is closed.

Next, the molding operation based on the above apparatus will be described. 6, the air cylinder 32 is driven to open the upper shutter 6A and the lower shutter 6b, and the motor 35
After the movable press rod 3, the hydraulic cylinder 5 and the holding frame 36 are integrally lowered by the rotating operation of the ball screw 35c by b, the work table 3a is lowered to the outside position of the furnace,
As shown in FIGS. 2, 4A, and 3A, the molding frame 7 on which the quartz glass body 8 is placed is placed on the work table 3a, and the work table is rotated by reversing the ball screw 35c. 3a is raised into the furnace space 50, and is raised to a position where the upper surface of the pedestal 10 almost comes into contact with the fixed press rod 19. In this state, 0.03 is applied to the quartz glass body 8 through the bottom plate 12 and the female die 13 by the hydraulic cylinder 5.
A pressing pressure of ˜0.04 Kgf / cm ² is applied. After the upper shutter 6A and the lower shutter 6B are closed by driving the air cylinder 32, when an airtight state is formed inside and outside the furnace body 30, the inert gas N ² is replaced and the pressure is set to about 1 atm.

Then, while heating the graphite heater 2 through the dielectric heating coil 2A, while measuring the temperature raising time with the thermometer 33, the temperature raising rate of the furnace space is 35 to 55 ° C. /
When rapidly heated at a temperature of min, preferably 45 to 50 ° C / min, heating deformation starts at around 1650 ° C, and a hydraulic cylinder for following this and maintaining a press pressure of 0.03 to 0.04 Kgf / cm ² Make a climb of 5. In this case, the rate of ascent is 2 to 10 mm / min, preferably 3 to 5 mm / min, while measuring with the pointer 3b / scale 4. The pointer 3b / scale 4 may be attached to the hydraulic cylinder 5 side as shown in FIG.

After the needle 3b / scale 4 is raised to the top dead center (maximum elevated position) of the female die 13 and the temperature is raised to a molding temperature of 1850 ° C. to 1960 ° C., the predetermined molding is completed. , At that position 5min-10mi
Hold n positions. It should be noted that the amount of rise (movement stroke amount) to the maximum raised position is calculated in advance. In the molding process state, as shown in FIG. 4, the gases such as CO, CO ² , SiC ² and SiC produced by the reaction between the quartz glass body 8 and the graphite molding frames 10 and 13 are indicated by arrows. Thus, it escapes to the furnace space 50 through the ventilation part of the pedestal 10 and the ventilation part of the female die 13. At this time, female type 1
In order to make the escape from the ventilation part 3 more efficient, a large number of through holes 12a may be bored in the bottom plate 12, or the female die 13 may be used as the bottom plate 12 without providing the bottom plate 12. .

Since the pressing pressure is applied even during the position holding time, the scale of the scale 4 indicated by the pointer 3b slightly rises. Therefore, by observing the rising speed of the pointer 3b, the scale automatically increases. Moreover, the completion of the deformation of the quartz glass body 8 can be detected. When the completion of displacement of the quartz glass is detected based on an algorithm created by preliminarily calculating the displacement amount while gazing at the pointer 3b indicating the scale of the scale 4 after holding the position, the hydraulic cylinder 5 is lowered to reduce the pressure. To release.

After releasing the pressure, the shutter 6 is opened,
The work table 3a is lowered by the elevating means 35 such as the ball screw 35c, the molding frame 7 is taken out from the table 3a in the heated state, the high temperature mold is moved to a cooling table (not shown), and quartz is used as shown in FIG. The cap 23 is covered to prevent the graphite from being oxidized. Then, after deburring and performing a predetermined cutting process, the process shifts to an annealing process, and the molded product is completed by performing a predetermined annealing process by holding at 1150 ° C. for 30 minutes and then gradually cooling.

On the other hand, after moving to the cooling table, the next molding frame 7 is placed on the work table 3A, and molding is performed by the same procedure as described above. In addition, after the second time, the temperature in the furnace is
Almost 1500 ° C-1600 ° C, which is already close to the glass melting temperature
Since it is maintained at the front and rear, the preload start temperature is about 15
The temperature is about 00 ° C. to 1600 ° C., but in any case, the heating and softening start temperature of the quartz glass body 8 is preferably 1600 to 1650 ° C. or lower.

By the way, it has been found that the material of the quartz glass is slightly different from that of the oxyhydrogen melted product and the electric melted product. The conditions for forming a good quartz glass article for both are that the first heating rate is 46.5 ° C./m.
In, the second time was almost the same as 129 to 183 ° C./min, but regarding other data, the oxyhydrogen melted product had a melt press temperature: 1860 ° C., a holding time: 5 min, a deformation rate: 4 mm / min, Pressing pressure: 0.03kg / c
m ² , and the electro-melted product has a melt pressing temperature: 1950
° C, holding time: 10 min, deformation rate: 3 mm / mi
n, press pressure: 0.04 kg / cm ² , and a good molded article of quartz glass article could be obtained.

According to such an embodiment, a press pressure is applied to the side of the female die 13 and the press pressure is set to a minute pressure in the range of 0.01 to 0.1 Kgf / cm ² for accurate molding. It is possible to keep the contact area between the quartz glass body 8 and graphite as low as possible.

It is preferable that the pressing pressure is preloaded from a temperature range before the silica glass body 8 is softened and deformed, that is, before 1600 ° C., and the deformation speed of the glass depends on the pressing pressure and / or the glass melting temperature. Although different, as a result of experiments, 0.07 mm / min to 8 mm / min, preferably 0.07 mm / min to 5 mm / min is preferable.
The reason for such variations is that, in the case of continuous operation, the deformation rate of the glass is 10 times or more faster after the second time when preheating is present than in the first time when the glass is raised from room temperature. This is because after the second time, the temperature in the furnace is already maintained at around 1500 ° C to 1600 ° C, which is close to the glass melting temperature. In addition, the reason why the temperature inside the furnace is maintained in this manner is that high heat can be maintained in the molding space because the inlet side of the housing 1 is set to the lower side.

Since the graphite die itself is made of a material having air permeability, the female die 13 and the pedestal 10 which are always in contact with the quartz glass body 8 during pressure molding are made to react with each other. CO generated by
^2. Gases such as SiC can be easily escaped outside the molding space. In addition, the fact that gases such as CO, CO ² and SiC can be easily escaped to the outside of the molding space prevents generation of silicon carbide on the glass surface, and further cracks occur after cooling due to the difference in thermal expansion. In addition to eliminating the drawback of deteriorating the yield, the slippage between the mold and the glass due to the adhesion of silicon carbide is aggravated, and the defect that the glass does not penetrate into the details of the mold can be solved.

Further, in an apparatus for molding a quartz glass article having a protrusion 17a on one flat surface side, by pressing pressure from the back side of the female die 13, the concave portions 13a, 13 are formed.
It is preferable that the softened quartz glass easily flow into c. However, if such a structure is adopted, the side facing the pedestal 10 located on the back side of the recesses 13a and 13c can be dented and no one can be formed. Will end up.

Therefore, a relief portion 10a is provided at a predetermined position of the pedestal 10 corresponding to the concave portion of the female die 13, and more specifically, a relief portion 10a having a volume equal to or slightly larger than the concave portion of the female die 13 is provided. It is possible to prevent the formation of depressions on the side facing the pedestal 10 by providing the molded glass while gathering the softened quartz glass therein. In this case, the escape portion 1
0a becomes a convex portion after completion of molding, which may be cut later by cutting.

[0056]

As described above, according to the present invention, it is possible to manufacture a quartz glass article that can be molded with high accuracy even when processing a quartz glass article having a protrusion, and continuous molding is also easy. It is extremely practical because it can be performed. It has various remarkable effects.

[Brief description of drawings]

FIG. 1 is a schematic view of a quartz glass body thermoforming apparatus according to an embodiment of the present invention.

2A is a cross-sectional view of a molding frame, FIG. 2B is a perspective view showing a molded product thereof, and particularly relates to a side plate of a horizontal boat shown in FIG. 2C.

3A is a sectional view of a molding frame, FIG. 3B is a perspective view showing the molded product, and particularly relates to the flange portion of the furnace core tube shown in FIG. 3C.

FIG. 4 shows a pressed state of the molding frame in FIG.

FIG. 5 shows a state in which a quartz cap is attached to the forming frame of FIG.

FIG. 6 is a detailed view of a hot pressing apparatus according to an embodiment of the present invention based on the basic configuration of FIG.

[Explanation of symbols]

 2, 2A Induction heating means 3a Work table 3C Pressure detection means 5 Fluid pressure urging means 6A Upper shutter 6B Lower shutter 7 Forming mold 8 Quartz glass body 13 Female type 15 Graphite frame 19 Support (fixed press bar) 35 Lifting Means 35c to 35A Ball screw mechanism 50 The furnace space

[Procedure amendment]

[Submission date] May 12, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Title: Apparatus for manufacturing quartz glass articles

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of a quartz glass article in which protrusions are formed on at least one surface of a quartz glass body, and in particular, a quartz glass member used in the semiconductor industry. , Protrusions, fitting portions, or the like, which are often used for flange parts of furnace core tubes, top and bottom plates of vertical wafer carriers, side plates of horizontal wafer carriers, quartz glass jigs such as furnace core tube caps, and parts thereof. The present invention relates to an invention for efficiently producing a quartz glass article having a flange portion and the like.

[0002]

2. Description of the Related Art Conventionally, in the case of manufacturing a quartz glass member having such a complicated shape, a welding rod of quartz glass is heated by a burner heating on a quartz glass flat plate to successively build up while melting and melting, and then a built-up portion. Was manufactured by grinding and shaping it into a predetermined shape, or shaving from a quartz block body. However, work time is extremely long in overlay processing with a welding rod, and bubbles are caught if the welding speed and heating temperature are not adjusted properly. Since it is a fire processing, there was a problem that the working time was bad. In addition, there are problems in that the material consumption is large when the block material is machined, and that it takes a long time for the grinding.

In order to solve such a drawback, a heat molding method for heating and softening the quartz glass body in the molding die to form the protrusion is being studied. In this type of molding, for example, as shown in JP-A-1-317132, after heating the quartz glass base material to a high temperature of 1600 to 1800 ° C. in a molding container, a molding pressure is applied from both directions symmetrical to the base material. In addition, it is configured to perform pressure molding, but in such a molding method, for example, in the publication, the molding pressure is 100 Kgf / cm.
^Since the graphite and the quartz glass forming the molding frame adhere to each other at a high pressure at a high temperature when the molding is performed at such a high pressure, CO and CO ₂ are further generated by the reaction between the graphite and the quartz glass. Generated SiO ₂ vaporized gas and entered these softened quartz glass to generate bubbles, and the SiC produced by the reaction adhered to the surface of the quartz glass and was cooled to room temperature. At this time, a crack is generated due to the difference in thermal expansion coefficient between the two.

Therefore, for example, Japanese Examined Patent Publication No. 62-50414
It is devised to CO ₂ to escape from the fiber layer by lining the graphite fiber cloth to the inner surface of the forming frame in No..
This technique, according to the actual examples disclosed in the specification, was held at 1850 ± 5 ° C. for 30 minutes and the inert gas N ²
The pressure molding was successful at 0.4 km / cm ² in the atmosphere. This is because the lining graphite fiber cloth is SiO ²
The vapor gas such as effluent is prevented from being mixed into the product as air bubbles to improve the yield.

[0005]

However, in the structure in which the fiber layer is lined, when the raw ingot melts and comes into close contact with the cushion material of the side wall, the exhaust gas passage becomes only the pores of the side wall cushion material, and the bottom side. In the mechanism having a projection on the bottom as in the article according to the present invention, the retention of the gas at the bottom leads not only to a very serious defect, but also to the female recess corresponding to the projection. It is virtually impossible to lay the cushion material uniformly.

In order to prevent such defects, an apparatus for setting the heating temperature as low as 1600 ° C. to 1700 ° C. and using a molding hole having a through hole having a pore size of about 3 mm and molding without pressurization is disclosed in Japanese Patent Laid-Open No. Hei 10 (1999) -31868. It is proposed in No. 5-17174.

However, in such a mechanism, the heating temperature is 1
Since the viscosity is as low as 600 ° C. to 1700 ° C. and no pressure is applied, the molten glass does not sufficiently wrap around the projection portion of the flat surface in the case of the article according to the present invention, and thus accurate processing is also impossible. It will be possible.

In view of the above-mentioned conventional drawbacks, the present invention is capable of forming a quartz glass article having no protrusions with no devitrification or cracks on the surface even when a quartz glass article having a protrusion is processed, and can be molded with high precision. It is an object of the present invention to provide an invention for producing a glass article.

[0009]

SUMMARY OF THE INVENTION The present invention relates to an apparatus for producing a quartz glass article having a projection on its flat side by press-molding a quartz glass body under high temperature heating, and its features are as follows: In a molding space having a graphite frame in the periphery, a female die corresponding to the protrusion is arranged on the lower surface side with the quartz glass body sandwiched, and a pedestal for the glass body is arranged on the upper surface side, and the female die and the pedestal are arranged. A porous graphite material, on the one hand, the graphite frames are respectively formed of a dense graphite material to form a molding mold, and a support body for fixing and supporting the pedestal on the upper surface side; and a lower surface facing the support body on the one hand. A work table placed at a position for mounting the molding frame, an elevating means for moving the work table up and down from the outside of the furnace to the inside of the furnace, and a fluid pressure energizing unit provided under the work table. Step, and preferably the upper surface of the pedestal is fixed to the support by raising of the elevating means, and then high temperature heating is performed by urging the quartz glass body with a minute pressure force through the female mold by the fluid pressure urging means. It is characterized in that pressure molding is performed below.

In this case, the fluid pressure urging means is constituted by a hydraulic cylinder via a pressure detecting means, and the minute pressure applied by the pressure detecting means to the softened quartz glass body via the female die is 0.01. It is preferable to be configured to be controllable within the range of 0.5 Kgf / cm ² . Further, it is preferable that the glass body housed in the mold is capable of generating heat by induction heating means in order to enable rapid temperature rise.

Further, in order to facilitate continuous molding, an opening is formed below a furnace space surrounded by the heating element, and the work table can be opened and closed through two shutters so that the work table can enter the furnace. In addition to the above, it is preferable that, of the two shutters, the upper shutter facing the furnace space is made of a single-layer graphite material, and the lower shutter located at the lower side is made of a laminated graphite material. Further, in order to enable more accurate molding, detection means for detecting the amount of movement of the fluid pressure urging means is provided, and the temperature in the furnace is 1700 to 1700.
After reaching the temperature range of about 2000 ° C. and detecting the deformation completion position of the quartz glass body by the detection means, holding the molding completion position for a predetermined time, and then returning the female die through the fluid pressure urging means. It is better to lower in the direction.

In order to maintain the deformation completion position with high accuracy, the moving speed of the female die is set to 2 to 10 mm / min while moving the female die in the pressing direction by the hydraulic cylinder constituting the fluid pressure urging means. Good to set.

[0013]

In order to perform accurate heating as described above,
It is necessary to perform high temperature heating at around 1700 to 2000 ° C. However, when high temperature heating is performed, as described above, due to the reaction between graphite and quartz glass, CO and C
O ₂ and further SiO ₂ vaporized gas is generated, and bubbles of quartz glass are generated, and cracks and devitrification occur. Such measures are taken from both the molding frame and the molding pressure device.

First, the molding frame will be described. In a method of molding a quartz glass article by sandwiching a quartz glass body between a female die having a graphite frame surrounding it and a pedestal,
As shown in FIG. 4, a female die and a pedestal (these are referred to as push die) are always in contact with the quartz glass body during pressure molding.
Therefore, due to the reaction with quartz glass, CO and C
O ₂ and SiC vapor are generated only on the pressing contact surface. Further, even if SiO ₂ vaporized gas is generated at the outer periphery of the glass body by heating the glass body, since the quartz glass body is not in contact with the surrounding graphite frame until just before the completion of molding, the gas is There is no need to consider the escape. Therefore, it is sufficient to provide the gas escape path only in the pair of pressing dies, but it is impossible to deform the former graphite fiber cloth according to the shape of the female projection.

On the other hand, as in the latter prior art, when the pores of about 3 mm are perforated, the silica glass has a high viscosity.
No problem occurs at 600-1700 ℃, but 1900 ℃
When the temperature is raised to, the viscosity of the quartz glass is significantly reduced, and the molded quartz glass article has irregularities on its surface.
Therefore, according to the present invention, the pressing die is formed by using porous graphite, such as sintered graphite, in which the graphite material itself has air permeability. That is, press this case preferably the gas permeability 0.1 cm ² value of /sec(P:1.5Kgf/cm ²⁾ or more, more preferably equipped with micro gas permeation hole group of 0.9 cm ² / sec longitudinal I am using a mold.

[0016] A graphite material having a bulk density of 1.5 g / cm ³ or less may be used as the porous graphite material, but if the bulk density is too low, damage or deformation will occur during pressure molding. Therefore, 1.2 ± 0.
It is preferable to set it to 2 g / cm ³ . Further, in order to perform accurate molding without causing damage or deformation during pressure molding, the compressive strength is 100 Kgf / cm ² or more, preferably 150 to 6
It is necessary to set 00 Kgf / cm ² and a Shore hardness of 10 or more, preferably about 15 ± 2.

On the other hand, since the pressing die is always in contact with the quartz glass body during pressure molding, if impurities are present on the graphite side due to the contact, the semiconductor poison is proportionally produced on the surface of the quartz glass body. Also, a cristobalite layer is formed, which also causes devitrification and cracking. Therefore, metal elements such as Na, K, Li, Ca, Mg, and Fe which cause the semiconductor poison and the cristobalite layer are 0.1 to 0.1%, respectively.
It is preferable to set it to 0.2 ppm or less.

On the other hand, in the vicinity of the completion of the molding of the quartz glass body, since the expansion output from the outer peripheral surface of the softened quartz glass body is urged to the inner wall surface of the graphite frame, the graphite frame is formed of a dense graphite material. However, it is necessary to make the bending strength several steps higher than the pressing die. Flexural strength towards the pressing mold in this case is 30kg / cm ² or more, preferably in the order may be set respectively for 50~300kg / cm ^2, bending strength of the graphite frame, more,
Specifically, it may be set to around 350 to 900 kg / cm ² . Therefore, the molding frame of the present invention is characterized in that the two types of graphite molds, that is, the female mold, the pedestal, and the graphite frame, have different compositions.

Next, the molding process will be examined. In this processing, as described above, the heating temperature is about 1700 to 2000 ° C,
Preferably, by setting it to 1840 to 1980 ° C,
Viscosity is low and molding can be facilitated. In this case, in the case of natural quartz glass produced by oxyhydrogen flame, the heating temperature is 18
About 40 to 1900 ° C, and in the case of natural quartz glass produced by the electric melting method, the heating temperature is set to about 1900 to 1960 ° C. In this case, the molding may be carried out without pressure, but if it is carried out without pressure, the pressing force changes due to the weight of the pressing die, which is not preferable. On the other hand, if the pressing force is set to a large value, the contact between the molding frame and the fused silica glass becomes too strong and the generation of reaction gas cannot be suppressed even if the molding frame is used. Therefore, in the present invention, the contact time and contact area between the molding frame and the fused silica glass in the high temperature heating region are set to be as small as possible. In addition, it is necessary to devise a device that can facilitate continuous molding.

Therefore, according to the present invention, there is provided a support body for fixedly supporting the pedestal on the upper surface side, a work table which is arranged at a lower position facing the support body and on which the molding frame is placed, and the work piece. A molding apparatus is proposed, which comprises an elevating means for elevating a table from the lower position outside the furnace to the inside of the furnace, and a fluid pressure urging means continuously provided under the work table.

That is, according to the present invention, after the upper surface of the pedestal is fixed to the support body by the elevation of the elevating means, a small pressure force is applied to the quartz glass body by the fluid pressure urging means via the female die, specifically, By carrying out pressure molding under high temperature heating while energizing a minute pressing force in the range of 0.01 to 0.5 Kgf / cm ² , preferably 0.02 to 0.2 Kgf / cm ² ,
It is possible to suppress the reaction by keeping the contact area between the quartz glass body and graphite as low as possible while maintaining accurate molding processing at a constant molding pressure. In this case, it is preferable to use a non-compressible hydraulic cylinder as the fluid pressure urging means, and particularly by constructing the hydraulic cylinder via the pressure detecting means, the pressing force can be maintained with high accuracy. Further, the minute pressing force applied to the quartz glass body through the female die by the fluid pressure urging means is pre-pressurized to the female die from a temperature range before the quartz glass body begins to be deformed, so that the degree of heating and softening is increased. Since it is gradually molded according to the above, it is possible to perform the molding process with high accuracy, which is preferable.

Further, according to the present invention, the structure is such that the work table arranged on the lower side pressurizes through the female die, and the female die is configured to directly bite into the softened quartz glass body. Therefore, it becomes possible to mold the projection with high accuracy. Further, since the pedestal on the upper side of the molding frame has a fixed pressure, it is sufficient to open only the lower side of the furnace where the work table moves up and down without opening the upper side of the furnace. As a result, with the conventional structure in which the upper part of the furnace is opened, the temperature inside the furnace decreases to near room temperature each time the inside of the furnace is opened, and the temperature rise time in the next molding process becomes extremely long. Since the atmosphere can be left in the furnace, it is extremely advantageous as an apparatus for continuous molding.

In this case, in order to facilitate continuous molding, the lower part of the furnace space surrounded by the heating element is opened, and two shutters are provided in the opening. The upper shutter facing the space is made of a single-layer graphite material with good heat insulation, and the lower shutter located at the lower side is made of, for example, a laminated graphite material that is alternately laminated with a quartz glass plate. The latter property can maintain the sealing property and strength. Further, the glass body is heated by the induction heating means so that the temperature can be quickly raised to the heating zone, and the molding time, in other words, the contact time between the molding frame and the fused silica glass is minimized. If the temperature rising rate is too fast, the temperature difference between the peripheral portion and the central portion of the glass body becomes large, and accurate molding cannot be performed. Therefore, in the present invention, the temperature rising rate of the glass body after heat-softening is 35 to 55 ° C./mi.
n, preferably 40 to 50 ° C./min.

The moving speed of the elevating means is to enable accurate molding even when the female projection has a complicated shape and without buckling, and to delay the molding time unnecessarily. , The moving speed of the elevating means is 2 to a slow speed.
It is set to 10 mm / min, preferably 3 to 5 mm / min. In this case, a detecting means for detecting the moving amount of the fluid pressure urging means is provided, and the temperature inside the furnace is 1700.
After reaching the temperature range of about 2000 ° C. and detecting the deformation completion position of the quartz glass body by the detection means, the molding completion position depends on the projection shape for a predetermined time, specifically, the shape of the protrusion.
It is preferable to hold for 15 to 15 minutes, preferably 5 to 10 minutes, and wait until the deformation of the quartz glass body is completed, and immediately after the completion of the molding, the female die is returned to the returning direction via the fluid pressure urging means. By lowering the pressure to release the pressure, it is possible to prevent the reaction between the molding frame and the fused silica glass and prevent the protrusion during molding.
A hydraulic cylinder is used as the fluid pressure urging means in order to maintain the deformation completion position with high accuracy and to enable accurate elevation control.

[0025]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are merely illustrative examples, without any intention of limiting the scope of the present invention thereto unless otherwise specified. Absent.

First, the molding frame used in this apparatus will be described.
FIG. 2 is an embodiment diagram showing the shape of the molding frame.
In which the side plates 51 of the lateral boat 50 shown has disclosed a structure of a forming frame to pressure molding in, the female die 13 corresponding recesses 13 a are top and the projection 51a of the side plate 51 in FIG. (B) It is open to the side. That is, the main molding frame is shown in FIG.
As shown in FIG. 5, a concave portion 13a corresponding to the protrusion 51a with the quartz glass body 8 sandwiched between the quartz glass body 8 is formed in a rectangular graphite frame forming a molding space composed of a graphite frame 15 and a bottom plate 12 made of dense graphite. Female mold 1
3 and the pedestal 10 are arranged so that the width between the pedestal 10 and the female die 13 can be reduced, and the outer shapes of the pedestal 10 and the female die 13 are slightly smaller than the inner shape of the rectangular graphite frame 15. It is set.

An arm-shaped relief portion 10a is provided at a predetermined position of the receiving base 10 corresponding to the concave portion 13a of the female die 13, and the relief portion 10a has a volume equal to or slightly larger than that of the concave portion 13a of the female die 13. Set to. And the female mold 13
The pedestal 10 is formed to be thick so as to withstand the compressive stress under the pressing load, and the graphite frame 15 is formed to be a thin rectangular frame so as to absorb heat well.

FIG. 3 is an embodiment showing another shape of the molding frame.
Quartz glass article of the present embodiment is provided with a protruding portion 56a as shown in FIG. (C), for example, functions as a flange 56 of the vertical furnace tube 55, the female mold 13 in FIG. (A) The recess 13a corresponding to the ring-shaped protrusion 56a is opened. As shown in (A), the main molding frame has the quartz glass body 8 sandwiched in a cylindrical graphite frame that forms a molding space composed of a graphite cylinder 15 made of dense graphite and a bottom plate 12. And the protrusion 56
The female die 13 having the concave portion 13 a corresponding to a and the pedestal 10 are arranged so that the width between the pedestal 10 and the female die 13 can be reduced. Also, the outer diameter of the female die 13 is set to be slightly small.

Further, the mandrel 16 is planted in the female die 13 to provide a central hole ( not shown) in the flange 56, but the central hole 56d may be cut after the completion of molding, and is always required. Not something.

[0030] Then the graphite making up the embodiments also female 13 and support 10 in any case, the gas permeability is 0.1 cm ² value of /sec(P:1.5Kgf/cm ²⁾ or more, preferably 0 It has a group of minute gas permeation holes of about 9.9 cm ² / sec, and has a bulk density of 1.5 g / cm.
² or less, preferably 1.24 g / cm ² , with a compressive strength of 1
00 Kgf / cm ² or more, preferably 160 Kgf / c
m ² around, Shore hardness of 10 or more, preferably around 15
Bending strength is 30 kg / cm ² or more, preferably 69 kg
/ Cm ² and the specific resistance is set to 40 μΩ · cm.

The purity of the graphite is Na,
0.1 ppm of K, Li, Mg, Ca, Cu and Al
Hereinafter, Fe is set to 0.15 ppm or less, and is produced at a purity higher than at least the purity of the quartz glass to be molded. The pedestal 10 and the graphite material of the female die 13 are formed by sintering or the like. In this case, the average particle diameter of the graphite is 30 to 100 μm, preferably 40 to
It is preferable to set it to 100 μm.

On the other hand, the dense graphite forming the graphite frame 15 and the bottom plate 12 has a bulk density of 1.77 to.
1.90 g / cm ² , compressive strength 700 to 1050 kg
f / cm ² , Shore hardness is about 50 to 90, bending strength is 370 to 900 kg / cm ² , and specific resistance is 0.9 to 1.
Set to 8 μΩ · cm.

It is preferable that the mandrel 16 to be implanted in the female die 13 is also made of the same material as that of the female die 13, but it is not always contacted during molding and heating, and is not necessarily limited.

Next, the basic structure of the molding apparatus using the molding frame will be described. FIG. 1 discloses a basic configuration diagram of a quartz glass article molding apparatus of the present invention. In FIG.
A graphite heater 2 that is open at the bottom and is heated by the electromagnetic induction action of an electromagnetic induction heating coil 2A disposed around the housing 1 is provided inside a graphite-made housing 1 having a gate-shaped cross section. 2, the induction heating coil 2A is power-controlled by the thermometer and other control devices shown in FIG. 6, and the room temperature is controlled to a set temperature. The movable press rod 3 having the work table 3a at the upper end is made of graphite, and the lower end is connected to the piston portion 5a of the hydraulic cylinder 5, and is vertically moved by driving the piston portion 5a via the load cell 3c. It is configured to be possible.

The molding frame 7 is placed on the work table 3a, and the molding frame 7 is pressed upward by the driving of the hydraulic cylinder 5, but the upper surface of the pedestal 10 located above the molding frame 7 is pushed. When the fixed press bar 19 comes into contact, the molding frame 7 is pressed in the vertical direction.
The fixed press bar 19 is made of graphite and is integrally fixed to the housing 1.

The load cell 3c arranged between the piston portion 5a of the hydraulic cylinder 5 and the movable press rod 3 is constructed so that the pressure during the pressing can be measured. A scale 4 is vertically installed on the side surface of the hydraulic cylinder 5, and the moving distance of the movable press rod 3 can be confirmed by a pointer 3b extending horizontally from the side face of the press rod 3. As a result, the amount of displacement of the movable press rod 3 against the molding frame 7 can be visually confirmed by observing the pointer 3b on the scale 4, and the completion of molding can be visually confirmed by confirming the rising position of the pointer 3b. .

Incidentally, this molding completion detection converts the moving amount of the pointer 3b into an electric signal such as a resistance change or a capacitor,
It is also possible to signal with a lamp or a buzzer. The lower entrance portion of the housing 1 is configured to be closed by a shutter 6, and the shutter 6 is made of heat-resistant carbon felt, and extends along the lower surface of the housing 1 by an air cylinder (not shown) or the like. It can be opened and closed. After the shutter 6 is closed, the inside of the housing 1 can be replaced with an inert gas such as N ² or Ar or He by a device (not shown). The movable press rod 3, the hydraulic cylinder 5, and the scale 4 are integrally movable up and down so that the movable press rod 3, the hydraulic cylinder 5, and the scale 4 can move in and out of the housing 1 by a ball screw or other elevating means 35 which will be described in detail later. After opening, the molding frame 7 can be replaced by lowering them through the elevating means 35 and pulling the work table 3a out of the housing 1.

Next, a hot press machine according to an embodiment of the present invention based on the above basic structure will be described with reference to FIG.
In the figure, the same reference numerals as those in FIG. 1 represent the same members.
Reference numeral 30 denotes a stainless steel molding furnace main body installed in a gate-shaped machine frame 34, in which a water cooling jacket (not shown) is wrapped around the outer peripheral side, while an opaque quartz tube 3 is provided on the inner wall side of the furnace main body 30.
An induction heating coil 2A is provided in a surrounding manner through 9,
On the inner peripheral side of the heating coil 2A, a furnace inner space 42 is formed, which is surrounded by a graphite heat insulating material 37 around the upper surface and the side wall and is open at the lower side.

A graphite heater 2 is disposed on the inner peripheral side of the side wall heat insulating material 37 and is induction-heated by high-frequency electromagnetic induction with the induction heating coil 2A. As described above, the heater 2 is configured to control the electric power of the induction heating coil 2A by the thermometer 33 outside the furnace and control the room temperature to the set temperature. On the axis of the heat insulating material 37 on the upper surface side, a fixed press rod 19 made of graphite hangs down toward the furnace space 42 side, and the upper portion of the press rod 19 is made of the heat insulating material 3.
7 is projected above. And the press rod 19 is a machine frame 3
Even if the work table 3a is fixed and the work table 3a is lifted to receive the hydraulic pressure through the pedestal 10, the fixed press rod 19 can always be held at a predetermined position.

On the other hand, below the work table 3a facing the fixed press bar 19 through the furnace space 42, the above-mentioned movable press bar 3 made of graphite, the water cooling rod 5a corresponding to the piston part of the hydraulic cylinder 5, and the Load cell 3
The hydraulic cylinders 5 are vertically connected via c, and these are connected to the nut portion 35a of the ball screw 35c via a holding frame 36.

The ball screw 35c is provided vertically along the vertical leg 34a of the machine frame 34 in parallel with the advancing / retreating direction of the hydraulic cylinder 5, and the motor 35b drives the ball screw 35c.
Is rotated to vertically move the hydraulic cylinder 5 via the nut portion 35a and the holding frame 36 that are screwed together.

The scale 4 is vertically attached to the side surface of the vertical leg 34a of the machine frame 34, the holding frame 36 is erected along the scale 4 in an L shape, and the scale 4 is erected on the erection portion 36a. Is provided with a pointer 3b that fits in the.

The shutter 6 is composed of an upper shutter 6A made of a graphite plate (single-layer graphite) and a lower shutter 6B formed by laminating a quartz glass plate and a graphite plate (laminated graphite), which are integrally formed with the air cylinder 32. Is configured so that it can move forward and backward along the horizontal direction. That is, the upper shutter 6A moves horizontally along the lower surface of the heat insulating material 38 so as to close the furnace space 50, while the lower shutter 6B horizontally moves along the lower surface of the furnace body 30 so as to close the furnace body 30. It is configured to be movable. The shutters 6A and 6B are both fitted around the axis of the movable press rod 3 so that the movable press rod 3 can move up and down even after the shutter is closed.

Next, the molding operation based on the above apparatus will be described. 6, the air cylinder 32 is driven to open the upper shutter 6A and the lower shutter 6b, and the motor 35
After the movable press rod 3, the hydraulic cylinder 5 and the holding frame 36 are integrally lowered by the rotating operation of the ball screw 35c by b, the work table 3a is lowered to the outside position of the furnace,
As shown in FIGS. 2, 4A, and 3A, the molding frame 7 on which the quartz glass body 8 is placed is placed on the work table 3a, and the work table is rotated by reversing the ball screw 35c. 3a is raised into the furnace space 50, and is raised to a position where the upper surface of the pedestal 10 almost comes into contact with the fixed press rod 19. In this state, 0.03 is applied to the quartz glass body 8 through the bottom plate 12 and the female die 13 by the hydraulic cylinder 5.
A pressing pressure of 0.04 Kgf / cm ² is applied. After the upper shutter 6A and the lower shutter 6B are closed by driving the air cylinder 32, when an airtight state is formed inside and outside the furnace body 30, the inert gas N ² is replaced and the pressure is set to about 1 atm.

Then, while heating the graphite heater 2 through the dielectric heating coil 2A, while measuring the temperature raising time with the thermometer 33, the temperature raising rate of the furnace space is 35 to 55 ° C. /
Upon rapid heating at a temperature of min, preferably 45 to 50 ° C./min, heating deformation starts at around 1650 ° C., and following this, a hydraulic cylinder for maintaining a press pressure of 0.03 to 0.04 Kgf / cm ^2. Make a climb of 5. The rising speed in this case is 2 to 10 mm / min, preferably 3 to 5 mm / min while measuring with the pointer 3b / scale 4.
It rises at a constant speed of min. The pointer 3b / scale 4 may be attached to the hydraulic cylinder 5 side as shown in FIG.

After the needle 3b / scale 4 is raised to the top dead center (maximum elevated position) of the female die 13 and the temperature is raised to a molding temperature of 1850 ° C. to 1960 ° C., the predetermined molding is completed. , At that position 5min-10mi
Hold n positions. It should be noted that the amount of rise (movement stroke amount) to the maximum raised position is calculated in advance. In the molding process state, as shown in FIG. 4, gases such as CO, CO ² , SiO ² and SiC produced by the reaction between the quartz glass body 8 and the graphite molding frames 10 and 13 are indicated by arrows. Thus, it escapes to the furnace space 50 through the ventilation part of the pedestal 10 and the ventilation part of the female die 13. At this time, female type 1
In order to make the escape from the ventilation part 3 more efficient, a large number of through holes 12a may be bored in the bottom plate 12, or the female die 13 may be used as the bottom plate 12 without providing the bottom plate 12. .

Since the pressing pressure is applied even during the position holding time, the scale of the scale 4 indicated by the pointer 3b slightly rises. Therefore, by observing the rising speed of the pointer 3b, the scale automatically increases. Moreover, the completion of the deformation of the quartz glass body 8 can be detected. When the completion of displacement of the quartz glass is detected based on an algorithm created by preliminarily calculating the displacement amount while gazing at the pointer 3b indicating the scale of the scale 4 after holding the position, the hydraulic cylinder 5 is lowered to reduce the pressure. To release.

After releasing the pressure, the shutter 6 is opened,
The work table 3a is lowered by the elevating means 35 such as the ball screw 35c, the molding frame 7 is taken out from the table 3a in the heated state, the high temperature mold is moved to a cooling table (not shown), and quartz is used as shown in FIG. The cap 23 is covered to prevent the graphite from being oxidized. Then, after deburring and performing a predetermined cutting process, the process shifts to an annealing process, and the molded product is completed by performing a predetermined annealing process by holding at 1150 ° C. for 30 minutes and then gradually cooling.

On the other hand, after moving to the cooling table, the next molding frame 7 is placed on the work table 3A, and molding is performed by the same procedure as described above. In addition, after the second time, the temperature in the furnace is
Almost 1500 ° C-1600 ° C, which is already close to the glass melting temperature
Since it is maintained at the front and rear, the preload start temperature is about 15
The temperature is about 00 ° C. to 1600 ° C., but in any case, the heating and softening start temperature of the quartz glass body 8 is preferably 1600 to 1650 ° C. or lower.

By the way, it has been found that the material of the quartz glass is slightly different from that of the oxyhydrogen melted product and the electric melted product. The conditions for forming a good quartz glass article for both are that the first heating rate is 46.5 ° C./m.
In, the second time was almost the same as 129 to 183 ° C./min, but regarding other data, the oxyhydrogen melted product had a melt press temperature: 1860 ° C., a holding time: 5 min, a deformation rate: 4 mm / min, Pressing pressure: 0.03kg / c
m ² , and the electro-melted product has a melt pressing temperature: 1950
° C, holding time: 10 min, deformation rate: 3 mm / mi
n, press pressure: 0.04 kg / cm ² , and thereby a good molded article of a quartz glass article could be obtained.

According to such an embodiment, a press pressure is applied to the female die 13 side, and the press pressure is set to a minute pressure in the range of 0.01 to 0.1 Kgf / cm ² for accurate molding. It is possible to keep the contact area between the quartz glass body 8 and graphite as low as possible.

It is preferable that the pressing pressure is preloaded from a temperature range before the softening deformation of the quartz glass body 8, that is, before 1600 ° C., and the deformation rate of the glass depends on the pressing pressure and / or the glass melting temperature. Although different, as a result of experiments, 0.07 mm / min to 8 mm / min, preferably 0.07 mm / min to 5 mm / min is preferable.
The reason for such variations is that, in the case of continuous operation, the deformation rate of the glass is 10 times or more faster after the second time when preheating is present than in the first time when the glass is raised from room temperature. This is because after the second time, the temperature in the furnace is already maintained at around 1500 ° C to 1600 ° C, which is close to the glass melting temperature. Further, the reason why the temperature in the furnace is maintained in this way is that the high temperature can be maintained in the molding space because the inlet side of the housing 1 is set to the lower side.

Since the graphite die itself is made of a material having air permeability, the female die 13 and the pedestal 10 which are always in contact with the quartz glass body 8 during pressure molding are made to react with each other. CO, C generated by
Gases such as O ² and SiC can easily escape to the outside of the molding space. In addition, the fact that gases such as CO, CO ² and SiC can be easily escaped to the outside of the molding space prevents generation of silicon carbide on the glass surface, and further cracks occur after cooling due to the difference in thermal expansion. In addition to eliminating the drawback of deteriorating the yield, the slippage between the mold and the glass due to the adhesion of silicon carbide is aggravated, and the defect that the glass does not penetrate into the details of the mold can be solved.

Further, in a device for molding a quartz glass article having a projection 51a on one flat surface side, by pressing pressure from the back side of the female die 13, the softened quartz glass easily flows into the concave portion 13a. However, if such a configuration is adopted, the side that faces the pedestal 10 located on the back side of the recesses 13a and 13c is recessed due to the flow into the recesses 13a and 13c, which causes drooping.

Therefore, a relief portion 10a is provided at a predetermined position of the pedestal 10 corresponding to the concave portion of the female die 13, and more specifically, a relief portion 10a having a volume equal to or slightly larger than the concave portion of the female die 13 is provided. It is possible to prevent the formation of depressions on the side facing the pedestal 10 by providing the molded glass while gathering the softened quartz glass therein. In this case, the escape portion 1
0a becomes a convex portion after completion of molding, which may be cut later by cutting.

[0056]

As described above, according to the present invention, it is possible to manufacture a quartz glass article that can be molded with high accuracy even when processing a quartz glass article having a protrusion, and continuous molding is also easy. It is extremely practical because it can be performed. It has various remarkable effects.

[Brief description of drawings]

FIG. 1 is a schematic view of a quartz glass body thermoforming apparatus according to an embodiment of the present invention.

2A is a cross-sectional view of a molding frame, FIG. 2B is a perspective view showing a molded product thereof, and particularly relates to a side plate of a horizontal boat shown in FIG. 2C.

3A is a sectional view of a molding frame, FIG. 3B is a perspective view showing the molded product, and particularly relates to the flange portion of the furnace core tube shown in FIG. 3C.

FIG. 4 shows a pressed state of the molding frame in FIG.

FIG. 5 shows a state in which a quartz cap is attached to the forming frame of FIG.

FIG. 6 is a detailed view of a hot pressing apparatus according to an embodiment of the present invention based on the basic configuration of FIG.

[Explanation of Codes] 2, 2A Induction heating means 3a Work table 3C Pressure detection means 5 Fluid pressure biasing means 6A Upper shutter 6B Lower shutter 7 Molding form 8 Quartz glass body 13 Female type 15 Graphite frame 19 Support (fixed) Press bar) 35 Elevating means 35c to 35A Ball screw mechanism 50 Space inside the furnace ────────────────────────────────── ────────────────────

[Procedure amendment]

[Submission date] May 15, 1995

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

FIG.

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

Front page continuation (72) Inventor Hiroshi Kimura 2-13-60 Kitafu, Takefu City, Fukui Prefecture Shinetsu Quartz Co., Ltd. Takefu Factory (72) Inventor Koichi Taniyama 3-1, 4 Kayayacho, Takefu City, Fukui Prefecture Fukui Shin-Etsu Quartz Co., Ltd. (72) Inventor Kiwa Fujii, No. 3 No. 3 Kayoya-cho, Takefu City, Fukui Prefecture Fukui Shin-Etsu Quartz Co., Ltd.

Claims (7)

[Claims] 1. An apparatus for producing a quartz glass article having a projection on a flat side by press-molding a quartz glass body under high temperature heating, wherein the quartz glass body is sandwiched in a molding space having a graphite frame in its periphery. A female die corresponding to the protrusion is arranged on the lower surface side, and a pedestal for the glass body is arranged on the upper surface side. The female die and the pedestal are formed of porous graphite material, while the graphite frame is formed of dense graphite material. And a support for fixedly supporting the pedestal on the upper surface side, and a work table placed on the lower side facing the support, on which the molding frame is placed. An apparatus for manufacturing a quartz glass article, comprising: an elevating means for elevating the work table from a lower position outside the furnace to an inside of the furnace; and a fluid pressure urging means continuously provided under the work table. 2. The upper surface of the pedestal is fixed to the support body by the elevation of the elevating means, and then a high pressure is applied to the quartz glass body by a fluid pressure urging means via a female die while heating the quartz glass body at a high temperature. 2. The apparatus for manufacturing a quartz glass article according to claim 1, wherein pressure molding is performed. 3. The apparatus for manufacturing a quartz glass article according to claim 1, wherein the glass body housed in the mold is configured to be capable of generating heat by induction heating means. 4. A furnace inner space surrounded by the heating element is opened below, and the work table is configured to be opened and closed through two shutters so that the work table can enter the furnace. 2. The apparatus for manufacturing a quartz glass article according to claim 1, wherein an upper shutter of the shutter facing the space in the furnace is made of a single-layer graphite material, and a lower shutter located at a lower side is made of a laminated graphite material. 5. The fluid pressure urging means is constituted by a hydraulic cylinder via a pressure detecting means, and the minute pressure applied by the pressure detecting means to the softened quartz glass body via the female die is 0.01. The apparatus for producing a quartz glass article according to claim 1, wherein the apparatus is controllable in the range of 0.5 Kgf / cm ^2. 6. A detection means for detecting the amount of movement of the fluid pressure urging means is provided, and the temperature in the furnace is 1700 to 2000 ° C.
After reaching the temperature range before and after and detecting the deformation completion position of the quartz glass body by the detection means, after holding the molding completion position for a predetermined time, the female die is returned in the returning direction via the fluid pressure urging means. The quartz glass article manufacturing apparatus according to claim 1, which is configured to be movable. 7. The quartz glass article manufacturing apparatus according to claim 1, wherein the moving speed is set to 2 to 10 mm / min while moving the female die in the pressing direction by a hydraulic cylinder that constitutes the fluid pressure urging means.