JP2805281B2 - Molded frame for manufacturing quartz glass articles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of a quartz glass article having irregularities formed on at least one surface of a quartz glass body, and particularly relates to a quartz glass member used for the semiconductor industry. Projections, fittings or flanges often used for quartz glass jigs and their parts such as a furnace core tube flange portion, a vertical wafer carrier ceiling plate or bottom plate, a horizontal wafer carrier side plate, and a furnace core tube cap. The present invention relates to an invention for efficiently manufacturing a quartz glass article having a part or the like.

[0002]

2. Description of the Related Art Conventionally, when a quartz glass member having such a complicated shape is manufactured, a welding rod of quartz glass is sequentially heated and welded on a quartz glass flat plate by a burner heating, and then a welding portion is formed. It has been manufactured by grinding and molding into a predetermined shape, or by shaving from a quartz block body. However, the working time is extremely long in the overlaying process using a welding rod, and when the adjustment of the welding speed and the heating temperature is not performed properly, bubbles are chewed. There was a problem that the working environment was bad because of the fire processing. In addition, there is a problem that the material unit consumption is large in the machining of the block material and that the grinding requires a long time.

In order to solve such a drawback, a heating molding method for heating and softening the quartz glass body during molding to form the projections has been studied. In this type of molding, it is necessary to set the molding temperature to about 1750 to 1900 ° C., which is higher than the heating softening temperature (1600 ° C.) of quartz glass, in order to enable accurate molding of the uneven portion. At very high temperatures, CO and CO ₂ are generated by the reaction between graphite and quartz glass, and furthermore, SiO ₂ evaporating gas is generated, and these gases enter the softened quartz glass and generate only bubbles. Instead, the SiC generated by the above reaction adheres to the surface of the quartz glass, and when the temperature is lowered to room temperature, cracks occur due to the difference in the coefficient of thermal expansion between the two.

For this reason, for example, Japanese Patent Publication No. 62-50414
Is devised as to line the graphite fiber cloth CO and CO _2, SiO ₂ vapor from said fibrous layer escapes to the inner surface of the forming frame in No.. According to a practical example disclosed in the specification, this technique is a method in which the pressure is maintained at 1850 ± 5 ° C. for 30 minutes and the pressure molding is performed at 0.4 km / cm ² in an inert gas N ₂ atmosphere. there were. This is to improve the yield by preventing the lining graphitic fiber cloth from escaping the vapor gas such as SiO ₂ and mixing it into the product as air bubbles.

[0005]

However, in the structure in which the fiber layer is lined, if the original ingot melts and comes into close contact with the cushioning material on the side wall, the exhaust gas passage is limited to the pores of the cushioning material on the side wall, and the exhaust gas passage is limited to the bottom side. In a mechanism having a protrusion on the bottom, such as an article according to the invention, the retention of gas at the bottom leads to very serious defects.

In order to prevent such a drawback, an apparatus in which the heating temperature is set to a low temperature of 1600 ° C. to 1700 ° C., a molding hole having a through hole having a diameter of about 3 mm, and molding without pressurization is disclosed in Japanese Patent Application Laid-Open No. HEI 9-163873. 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 the pressure is not applied, in the case of the article according to the present invention, the molten glass cannot be sufficiently wrapped around the flat protruding portion, so that accurate processing is also impossible. Will be possible.

The present invention has been made in view of the above-mentioned conventional disadvantages, and even when a quartz glass article having an uneven portion is processed, the quartz can be formed with high accuracy without bubbles and without devitrification or cracks on the surface. An object of the present invention is to provide an invention for producing a glass article, particularly a molding frame.

[0009]

First, a molding method used in the present invention will be described. In this processing, the heating temperature is 175
0-2000 ° C, preferably 1840-1960 ° C
Set to. In this case, the heating temperature is set to around 1840 to 1900 ° C. for natural quartz glass manufactured by an oxyhydrogen flame, and to 1900 to 1960 ° C. for natural quartz glass manufactured by an electrofusion method. This lowers the viscosity because the heating temperature is not low as in the latter prior art. In the case of the present invention, molding may be performed without pressure, but if performed without pressure, the pressing force changes due to the weight of the pressing die, which is not preferable. On the other hand, if the pressure is set to a large value, the contact between the graphite frame and the fused silica glass becomes too strong, which causes problems due to generation of a reaction gas, devitrification due to sticking of SiC, and generation of a cristobalite layer. Therefore, in the molding method used in the present invention, pressure molding is performed under the high-temperature heating and with a pressing force in the range of 0.01 to 1 kgf / cm ² .

Although such a processing method is also novel, the present invention particularly specifies the molding frame, surrounds the molding space for manufacturing a quartz glass article having a concave-convex portion on a flat surface side, and surrounds the molding space. Molding of a quartz glass body comprising a graphite frame and a pair of opposed graphite molds corresponding to the concave and convex portions with the quartz glass body interposed in the graphite frame, and the width between the opposed graphite molds can be reduced. In the mold, the graphite frame and the pair of graphite molds have different compositions.

[0011] That is, in the present invention is a pair of mold facing contact with the pressure molding during quartz glass body, gas permeability 0.1 cm ² value of /sec(P:1.5Kgf/cm ²⁾ or And a compressive strength of 100 kgf / cm ² or more,
It is preferably formed of a high-purity graphite material having 150 to 600 kgf / cm ² , a shore hardness of 10 or more, preferably about 15 ± 2, and having a large number of fine gas permeable holes such as sintered graphite and having air permeability. On the other hand, in the vicinity of the completion of molding of the quartz glass body, in the graphite frame pressed against the outer peripheral surface of the swollen quartz glass body, the pair of opposed graphite molds (hereinafter referred to as “push molds”).
It is characterized in that it is formed of a graphite material whose bending strength is several steps higher.

In this case, the bulk density of the pressing die is set to 1.5
g / cm ³ or less, preferably 1.2 ± 0.2 g / cm ³ ,
Flexural strength of 30 kg / cm ² or more, preferably 50 to 3
It is better to set each to 00 kg / cm ² . The graphite purity of the press mold is higher than the purity of the quartz glass body. More specifically, 0.1 to 0.1% each of metal elements that cause semiconductor poisons such as Na, K, Li, Ca, Mg, Fe and the cristobalite layer. It is preferable to set the concentration to 0.2 ppm or less.

The pressing pressure applied to the pressing die is set in the range of 0.01 to 0.1 kgf / cm ² , and the average particle size of graphite forming the pressing die is 30 to 150 μm, preferably 50 to 50 μm. It is better to set it to μ100 μm.

Further, the pressing die is composed of one or more plural combinations, and it is set so that the glass body can be easily removed from the pressing die after molding and the graphite die can be prevented from being damaged. Good.

In a molding frame used in an apparatus for molding a quartz glass article by the high-temperature pressure molding, a pressing pressure is applied from one of a pair of opposed graphite dies, and a relief portion is provided at a predetermined position on the other side. It is good to provide.

[0016]

According to the method of molding a flat article having an uneven portion while a quartz glass body is sandwiched between a pair of opposed pressing dies as in the above-mentioned molding method, and the opposed pressing dies are reduced in width, FIG. As shown in the figure, the pair of pressing dies that are always in contact with the quartz glass body during the pressure molding are a pair of pressing dies. Therefore, it is the pressing dies that generate CO, CO ₂ , SiO _2, etc. by the reaction with the quartz glass. Only the contact surface. Also, even if the SiO ₂ evaporating gas is generated around the glass body due to the heating of the glass body, the quartz glass body is not in contact with the surrounding graphite frame until immediately before the molding is completed. You don't have to worry about escape. Therefore, it is sufficient to provide a 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 concave and convex portions of the die.

On the other hand, in the case where the pores of about 3 mm are perforated as in the latter conventional technique, quartz glass having a high viscosity is used.
No problem occurs at 600 to 1700 ° C, but 1900 ° C
When the temperature is raised to such a level, the viscosity of the quartz glass is greatly reduced, and irregularities are formed on the surface of the molded quartz glass article.
Therefore, in the present invention, a stamping die is formed by using a material having a gas-permeable graphite material itself, such as sintered graphite.

That is, the gas permeability is 0.1 cm ² / sec
(P: a value of 1.5 kgf / cm ² ) or more, preferably about 0.9 cm ² / sec. And the bulk density is 1.5 g / cm
A graphite material of ³ or less may be used, but if the bulk density is too low, breakage or deformation occurs during pressure molding. Therefore, it is preferable to set the value to 1.2 ± 0.2 g / cm ³ . In order to mold with high precision without causing breakage or deformation during pressure molding, the compression strength is 100 kgf /
cm ² or more, preferably 150 to 600 kgf / c
It is necessary to set m ² and Shore hardness to 10 or more, preferably around 15 ± 2.

On the other hand, in the vicinity of the completion of molding of the quartz glass body, since the expansion force from the softened outer peripheral surface of the quartz glass body is urged against the inner wall surface of the graphite frame, the bending strength of the graphite frame is smaller than that of the pressing die. It needs to be several steps larger. In this case push-type bending strength 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 350 It needs to be around 900 kg / cm ² .

Since the pressing die is always in contact with the quartz glass body at the time of press molding, if impurities are present on the graphite side due to the contact, the semiconductor poison will be proportionally applied to the surface of the quartz glass body. And cristobalite layer is formed,
It also causes devitrification and cracks. So N
a, K, Li, Ca, Mg, Fe, etc .;
It is better to set it to 2 ppm or less.

Even if the above configuration is adopted, the reaction always occurs at a high temperature. Therefore, in the present invention, a pressing pressure is applied to the one of the opposing pressing dies, the pressure is set to a minute pressure in the range of 0.01 to 0.1 kgf / cm ² , and the graphite forming the pressing dies is applied. By setting the average particle size to 30 to 150 μm, preferably 50 to 100 μm, the contact area between the quartz glass body and graphite is reduced as much as possible while maintaining accurate molding, thereby suppressing the reaction.

Further, in a device for molding a quartz glass article having an uneven portion on one flat surface, by applying a pressing pressure from one of a pair of pressing dies facing each other, the softened quartz glass easily flows into the recess. It is preferable, but if such a configuration is adopted, the glass body on the side located on the back side (the other side) corresponding to the flow into the graphite-type concave portion is generated, and a concave is formed. Therefore, a relief portion is provided at a predetermined position of the mold facing the press mold on the side to which the press pressure is applied, and molding is performed while collecting the softened quartz glass, thereby forming a recess on the side facing the recess of the press mold. Formation can be prevented. Note that the relief portion becomes a convex portion after the molding is completed, and it may be cut later by cutting.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not merely intended to limit the scope of the present invention, but are merely illustrative examples unless otherwise specified. Absent.

FIG. 1 is a basic configuration diagram of a quartz glass article molding apparatus according to an embodiment of the present invention. In the drawing, the lower part is opened, and a graphite casing 1 having a gate-shaped cross section is provided.
Inside, a graphite heater 2 for heating by an electromagnetic induction action of an electromagnetic induction heating coil 2A arranged around the housing 1 is provided, and the heater 2 is guided by a thermometer (not shown) and other control devices outside the housing 1. The power of the heating coil 2A is controlled, and the room temperature is controlled to the set temperature. The movable press rod 3 provided with a 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 moves up and down by driving the piston portion 5a via the load cell 3c. It is configured to be possible. The work frame 3 is mounted on the work table 3a.
Is pressed upward by the drive of the hydraulic cylinder 5, but when the fixed press rod 19 abuts on the upper surface of the pressing die 10 located above the molding frame 7, the molding frame 7 is pressed from above and below. . Note that the fixed press bar 19 is formed of graphite and is fixed to the housing 1 integrally.

The load cell 3c disposed between the piston portion 5a of the hydraulic cylinder 5 and the movable press rod 3 is configured to measure the pressure during the pressing. A scale 4 is provided vertically on the side surface of the hydraulic cylinder 5 so that the pointer 3b extending horizontally from the side surface of the press rod 3 allows a user to check the distance of movement of the movable press rod 3. As a result, the amount of displacement of the movable press rod 3 pressed against the molding frame 7 can be visually recognized 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. .

The completion of the molding is detected by converting the amount of movement 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 of the housing 1 is configured to be able to be closed by a shutter 6, and the shutter 6 is made of heat-resistant carbon felt. 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 as to be able to enter and withdraw from the housing 1 by a ball screw or other elevating mechanism (not shown). By lowering the work table via the elevating mechanism and extracting the work table out of the housing 1, the molding frame 7 can be replaced.

FIG. 2 is a view showing one embodiment of the shape of the molding frame. The side plate 5 of the horizontal boat 50 shown in FIG.
This discloses a structure of a molding frame for press-molding 1, and a concave portion 13 a corresponding to the convex portion 51 a of the side plate 51 shown in FIG. That is, as shown in FIG. 2A, the quartz glass body 8 is placed in a rectangular graphite frame which forms a molding space composed of a graphite frame 15 made of dense graphite and a bottom plate 12 as shown in FIG. the placing and pressing mold 10 facing thereto and a concave 13 having a recess 13 a corresponding to the protrusions 51a interposed therebetween, the pressing mold 10 and the concave 13 between the possible width reduction of the inner shape of rectangular graphite frame 15 Press mold 10 and concave mold 1
3 is slightly smaller.

An arm-shaped relief portion 10a is provided at a predetermined position of the pressing die 10 corresponding to the concave portion 13a of the concave shape 13, and the relief portion 10a is set to have a volume equal to or slightly larger than the concave portion 13a of the concave shape 13. I do. The concave mold 13 and the pressing mold 10 are formed to be thick so as to withstand the compressive stress at the time of press 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 the convex portion 56 as shown in Figure a
For example, it functions as a flange portion 56 of a vertical furnace tube 55, and a concave portion 13a corresponding to the ring-shaped convex portion 56a is opened in the concave mold 13. Then, as shown in FIG. 2A, the quartz glass body 8 is placed in a cylindrical graphite frame which forms a molding space 11 composed of a graphite cylinder 15 made of dense graphite and a bottom plate 12, as shown in FIG. The concave portion 13 corresponding to the convex portion 17c
a , and the outer diameters of the pressing mold 10 and the concave mold 13 are slightly smaller than the inner diameter of the cylindrical graphite cylinder 15 so that the width between the pressing mold 10 and the concave mold 13 can be reduced. Is set to small. In addition, the center column 16 is provided with the flange 5
The center hole 56d is implanted in the concave mold 13 in order to provide the center hole 56d, but the center hole 56d may be cut after completion of molding, and is not always required.

[0030] Then the graphite making up the embodiments also concave 13 and the push-type 10 one has a gas permeability 0.1 cm ² value of /sec(P:1.5kgf/cm ²⁾ or more, preferably 0. It has a group of small gas permeable holes of about 9 cm ² / sec, and a bulk density of 1.5 g / cm.
³ or less, preferably 1.2 g / cm ³ , and a compressive strength of 10
0 kgf / cm ² or more, preferably 160 kgf / cm
Around ² , Shore hardness of 10 or more, preferably around 15 and flexural strength of 30 kg / cm ² or more, preferably 69 kg / cm ²
cm ² , and the specific resistance is set to 40 μΩ · cm.

The purity of the graphite is Na,
0.1 ppm each of K, Li, Mg, Ca, Cu and Al
Hereinafter, Fe is set to 0.15 ppm or less, and is manufactured at a higher purity than at least the purity of quartz glass to be molded. The graphite material of the pressing mold 10 and the concave mold 13 is formed by sintering or the like. In this case, the average particle size of the graphite is 30 to 150 μm, preferably 50 to 1 μm.
It is good to set it to 00 μm.

On the other hand, the dense graphite constituting the graphite frame 15 and the bottom plate 12 has a bulk density of 1.8 to 1.
9 g / cm ³ , compressive strength is 700 to 1050 kgf / c
m ² , Shore hardness is around 50-90, flexural strength is 370
９００900 kg / cm ² , specific resistance 0.9-1.8 μΩ
・ Set to cm.

It is preferable that the center pillar 16 implanted in the concave mold 13 is formed of the same material as the concave mold 13, but it is not always in contact during molding and heating, and is not necessarily limited.

According to this embodiment, the concave mold 13 and the press mold 10 which are always in contact with the quartz glass body 8 during pressure molding are formed of a material having air permeability, and the quartz material itself is made of quartz. Gases such as CO, CO ₂ , and SiC generated by the reaction between glass and graphite can be easily released to the outside of the molding space. In addition, the fact that gases such as CO, CO ₂ , and SiC can easily escape to the outside of the molding space prevents silicon carbide from being formed on the glass surface, and furthermore, cracks occur after cooling due to differences in thermal expansion. In addition to eliminating the drawback that the yield is deteriorated, it is possible to eliminate the disadvantage that the slip between the mold and the glass due to the adhesion of silicon carbide is deteriorated and the glass does not enter the details of the mold.

When devitrification (crystallization) due to impurities occurs on the contact surface where the molds 10 and 13 and the glass body 8 are in contact with each other, slippage between the molds 10 and 13 and the glass body 8 is eliminated, and molding is difficult. However, since the purity of the concave mold 13 and the pressing mold 10 is set higher than the purity of the surface of the quartz glass body 8,
The disadvantages are prevented. Also, even if the above configuration is adopted, the reaction always occurs at a high temperature.

Therefore, in this embodiment, a pressing pressure is applied to the concave mold 13 side, and the pressing pressure is set to a minute pressure in the range of 0.01 to 0.1 kgf / cm ² so that accurate molding can be performed. The contact area between the quartz glass body 8 and the graphite can be reduced as much as possible while maintaining it.

Further, in a device for molding a quartz glass article having a convex portion 17a on one flat surface side, by applying a pressing pressure from the back side of the concave mold 13, softened quartz glass easily flows into the concave portion, It is preferable, but if such a configuration is adopted, the glass body facing the pressing die 10 located on the rear side of the scalpel portion is dripped by the flow into the scalpel portion, and a dent is formed.

Therefore, a relief portion 10a is provided at a predetermined position of the pressing die 10 corresponding to the concave portion of the concave mold 13 from the relief portion 10a, specifically, a volume set to be equal to or slightly larger than the concave portion of the concave mold 13. By molding while collecting the softened quartz glass, the dent of the glass body on the side facing the pressing die 10 can be prevented. In this case, the relief portion 10a becomes a convex portion after the completion of molding, but it may be cut later by cutting.

The molding frame is provided with a concave 13 through a bottom plate 12.
Pressing pressure is applied through the hydraulic cylinder from the back side of the, but in this case, if the pressing pressure is too high, care must be taken because the softened glass will buckle or cause abnormal deformation and entrapment of air bubbles etc. is there. In this embodiment, since the heating temperature is set to a high temperature of 1840 to 1960 ° C., when the pressing force is set to a large value, the contact between the concave mold 13 and the fused silica glass becomes too strong, and the reaction gas Problems arise due to formation and devitrification due to sticking of SiC, and formation of a cristobalite layer. Therefore, in this embodiment, the pressing pressure is set to a pressure of 0.01 kg / cm ^{2 to} 0.1 kg / cm ² .

The pressing pressure is preferably pre-pressed from a temperature range before the quartz glass body 8 softens and deforms, that is, from before 1600 ° C., and the deformation rate of the glass is determined by the pressing pressure and / or the melting pressing temperature. Although different, as a result of experiments, it is preferably from 0.07 mm / min to 8 mm / min, more preferably from 0.07 mm / min to 5 mm / min.
The reason for such variation is that in the case of continuous operation, the deformation speed of the glass is increased by 10 times or more in the second and subsequent times where the preheating is present as compared with the first time when the temperature is raised from room temperature. This is because the temperature in the furnace is already maintained at 1600 ° C., which is near the melting press temperature, after the second time. Also, the temperature in the furnace is maintained in this way by the case 1
The reason is that the high heat can be maintained in the molding space by setting the inlet side of the lower side.

Next, the operation based on the above embodiment will be described. In FIG. 1, a shutter 6 is opened, and a movable press rod 3, a hydraulic cylinder 5, and a scale 4 are lowered integrally by operating an elevating mechanism (not shown), and FIGS. 2 (A) and 3 (A).
Then, as shown in FIG. 4, the molding frame 7 on which the quartz glass body 8 is placed is placed on the work table 3a and is raised into the housing 1, and the upper surface of the pressing die 10 almost contacts the fixed press rod. And raise it to near. In this state, a hydraulic cylinder 5 applies a pressing pressure of 0.03 to 0.04 kgf / cm ² to the quartz glass body 8 via the bottom plate 12 and the concave mold 13. The trailing shutter 6 closes, the air-tight state inside and outside of the housing 1 is formed, is set to approximately 1 atmosphere replaced with an inert gas N _2.

When the graphite heater is rapidly heated through a dielectric heating coil while measuring the temperature rise time with a thermometer (not shown), heating deformation starts at about 1600 ° C. Raise the hydraulic cylinder to maintain a press pressure of 04 Kgf / cm ² . Then, after the quartz glass is sufficiently softened and filled in the molding space, in other words, at 1850 ° C. to 1960 ° C. for 5 minutes.
Hold the position for 10 to 10 minutes. In the molding state, for example, as shown in FIG. 4, CO, C generated by the reaction between the quartz glass body 8 and the graphite molds 10 and 13 are formed.
Gases such as O ₂ , SiO ₂ , and SiC escape to the molding space via the ventilation part of the pressing mold 10 and the ventilation part of the concave mold 13 as shown by arrows. At this time, in order to make the escape from the ventilation portion of the concave mold 13 more efficient, a large number of through holes 12 are formed in the bottom plate 12.
a may be perforated, or the concave mold 13 may be used as the bottom plate 12 without providing the bottom plate 12.

After the position is held, the pointer 3b indicating the scale of the scale 4 is watched, and when the completion of the displacement of the quartz glass is detected based on an algorithm which is calculated in advance, the shutter 6 is opened. Then, the work table 3a is lowered by a lifting mechanism (not shown), the molding frame 7 is taken out from the table 3a, and covered with a quartz cap 23 as shown in FIG. 5 to prevent oxidation of carbon. Thereafter, after holding at 1150 ° C. for 30 minutes, the molded product can be formed by performing annealing treatment by slow cooling, and it is completed by removing the burrs or the like by appropriate cutting processing. 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, the scale of the quartz glass is automatically adjusted. It is possible to detect the completion of the deformation.

By the way, as for the material of quartz glass, experimental results slightly different from those of the oxyhydrogen-melted product and the electro-melted product have been found. The conditions for molding the quartz glass article, which are good in both cases, are as follows: the first heating rate is 46.5 ° C./m
in, the second time was the same as 129 to 183 ° C./min, but for the other data, the oxyhydrogen melt was melt-pressed at 1860 ° C., holding time: 5 min, deformation speed: 4 mm / min, pressed Pressure: 0.03 kg / cm
² , and the electro-melted product has a melting press temperature of 1950
° C, holding time: 10 min, deformation speed: 3 mm / mi
n, the pressing pressure was 0.04 kg / cm ² , whereby a good molded quartz glass article could be obtained.

[0045]

As described above, according to the present invention, even in the case of processing a quartz glass article having an uneven portion, it is possible to perform a molding process with no bubbles, no devitrification or cracks on the surface, and high precision. In addition to being able to manufacture various quartz glass articles,
It is very practical because continuous molding can be easily performed. And so on.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an apparatus for heating and forming a quartz glass body according to an embodiment of the present invention.

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

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

FIG. 4 shows a pressed state of the molding frame of FIG. 2;

FIG. 5 shows a state in which a quartz cap is attached to the molding frame of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 2 Heater 7 Mold 8 Quartz glass body 10 Push mold 13 Recess 112,15 Cylindrical graphite frame

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C03B 20/00 C03B 11/00

Claims (6)

(57) [Claims] 1. A mold for manufacturing a quartz glass article by press-molding a quartz glass body under high-temperature heating of about 1750 to 2000 ° C. and at a pressure of 0.01 to 1 kgf / cm ² . A pair of graphite molds are arranged in a graphite frame surrounding a molding space at positions opposed to each other with the quartz glass body interposed therebetween, and they are formed of a quartz glass body mold that can be reduced in width. A pair of opposed graphite molds, which are subjected to pressure molding while contacting the body, have a gas permeability of 0.1 cm ² / sec.
c (P: a value of 1.5 kgf / cm ² ) or more, a compressive strength of 100 kgf / cm ² or more, and a Shore hardness of 10 or more, which is made of a high-purity graphite material having a group of fine gas permeable holes. A molding frame for molding a quartz glass body, characterized in that the graphite frame is formed of a graphite material whose bending strength is several steps higher than a pair of graphite molds facing each other. 2. The pair of graphite molds facing each other have a bulk density of 1.5 g / cm ³ or less and a bending strength of 30 kgf.
The molding frame according to claim 1, wherein each of the molding frames is set to at least / cm ^2. 3. The molding frame according to claim 1, wherein the purity of said pair of opposed graphite types is set higher than the purity of the quartz glass body. 4. The molding frame according to claim 1, wherein one or more of the pair of opposed graphite dies are set in combination. 5. The pressing pressure applied to the pair of opposed graphite molds is set in a range of 0.01 to 0.1 kgf / cm ² , and the average particle size of the graphite forming the opposed graphite molds is 30. The molding frame according to claim 1, which is set to be from 150 to 150 m, preferably from 50 to 100 m. 6. A molding frame for use in an apparatus for molding a quartz glass article by high-temperature press molding, wherein a pressing pressure is applied from one of a pair of opposed graphite dies and a relief portion is provided at a predetermined position on the other side. The molded frame according to claim 1,