JP2001302256A - Core shaft for producing quartz glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a core shaft which is used for producing quartz glass, has good heat resistance, excellent load resistance and excellent processability and enables the precise production of a large synthetic quartz glass article at a low cost. SOLUTION: This core shaft which is used for producing the synthetic quartz glass article comprises a member obtained by joining two or more columnar or cylindrical carbon fiber-reinforced carbon composite material members to each other at screw portions in series.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mandrel used for manufacturing a synthetic quartz glass body, and more particularly to a mandrel for manufacturing quartz glass used for a method of manufacturing a large-sized synthetic quartz glass body with high accuracy and at low cost. .

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a high-purity synthetic quartz glass body such as a base material for an optical fiber, a cylindrical or cylindrical heat-resistant substrate having a smooth outer peripheral surface is rotated, and the surface of the quartz glass is rotated. An external method (Outside Vapor Deposition) in which fine particles are sprayed and adhered to form a porous quartz glass base material, and then the porous quartz glass base material on the heat-resistant substrate or the mold is heated to be transparently vitrified.
Method (hereinafter, referred to as “external method”) or a vapor phase method (Vapor-Phase) in which fine quartz glass particles are deposited in the axial direction of a seed rod to form a porous quartz glass base material, and the glass material is heated and made transparent. Axial Deposi
Tion Method (hereinafter referred to as “axis setting method”) or the like is used. The seed rod or heat-resistant substrate used in these manufacturing methods, or a mold body (hereinafter, collectively referred to as a "mandrel") for extracting and inserting the substrate during vitrification includes quartz glass, alumina, zirconia, mullite,
Or, in addition to ceramics such as boron nitride, materials such as graphitized carbon material (graphite carbon), silicon carbide, and silicon nitride are generally used. In recent years, carbon fiber reinforced carbon composite materials are one of suitable materials. (Carbon
Fiber Reinforced Carbon C
(hereinafter referred to as “C / C composite”).

However, quartz glass bodies used for optical fiber preforms, members of semiconductor manufacturing equipment, and the like have recently been required to be further increased in size and reduced in cost. There is a need for scaling. However, in the case of the carbon-based compound, as the size of the compound increases, problems in the production and synthesis of the material, problems in processing accuracy, and the like increase. It has been said that it is very difficult to practically use one having an outer diameter exceeding this. In addition, in order to obtain a mandrel that can withstand practical use, it is necessary to secure the strength of the mandrel itself at the same time as making it longer, so that a cylindrical mandrel has a larger outer diameter and a cylindrical mandrel has a thicker The thickness of the mandrel must be increased, which inevitably increases the size of the mandrel and increases the weight, and also causes a problem of poor handling.

[0004]

As described above, when a carbon-based compound is used as a material, it is very difficult to manufacture a mandrel having a length exceeding 1000 mm. Therefore, a plurality of members such as rods are joined in series. In some cases, the entire mandrel may be lengthened. As a method of lengthening by joining, a method of connecting a plurality of members using various various jigs, such as making a hole near the end of the member and locking it with a joining pin, has been made. A mandrel made of a carbon-based compound having a certain strength has also been made possible. However, with the recent increase in the size of optical fiber preforms and other materials, the synthesis of precursors (called porous quartz glass bodies and soot bodies) of the preforms and the sintering (transparent vitrification) of the precursors are called for. In this case, the load applied at the time increases, and in the case of locking by the conventional joining pin, a situation has occurred in which the pin cannot be withstand a large load and breaks. If the pins at the joints are damaged in this way, the joining of the mandrel will be incomplete, for example, when the porous quartz glass base material is sintered, it deforms and satisfies the desired shape. A quartz glass preform for optical fibers could not be obtained, or even a facility such as a heating furnace could be destroyed due to a drop of the porous quartz glass preform to be sintered. In other words, a very large porous quartz glass member (for example, a member having a weight close to 1 t or 1 t in the future)
However, the point that there was no mandrel having a strength enough to hold the large synthetic quartz glass body was restricted to manufacture a large-sized synthetic quartz glass body with high accuracy and at low cost. Therefore, in order to realize a longer mandrel while maintaining excellent heat resistance and load resistance, it is an important issue how to join mandrel members such as rods using any means. I was

As described above, in the case of joining with a conventional pin or other locking jig, as the size of the quartz glass body increases, the jig may not be able to withstand a large load applied to the mandrel and may be damaged. It becomes inevitable.
(For example, when the locking pin is used, the load may concentrate on the pin, and the pin may be broken.) This improves the load resistance of a member such as a rod. However, this is a problem that cannot be overcome unless the fundamental strength of the joint is increased. When the locking pin is used, the diameter of the pin insertion hole 8 must be larger than the diameter of the pin 9 for handling as illustrated in FIG. Has a gap in it, which causes "lash" and causes bending of the mandrel itself. For these,
Similar problems cannot be avoided as long as a jig is used instead of the pin, and no effective means for solving the problem of how to attach the jig to the mandrel member has not been found. Therefore, in the conventional joining method using pins and other jigs, when a mandrel for holding a very large porous quartz glass base material (for example, having a weight exceeding 1 t) or the like is required in the future, if the mandrel is required, Depending on the weight of the quartz glass base material, the manner of treatment and handling in each step, etc., it is expected that the possibility of bending or breakage of the joined portion will be considerably increased. Therefore, studies have been made on a method of firmly joining members without using jigs.

The present invention has been made in view of the above-mentioned problems and problems, and has as its object to provide a quartz glass manufacturing mandrel having good heat resistance, excellent load resistance and workability.

It is another object of the present invention to provide a quartz glass manufacturing mandrel capable of manufacturing a large synthetic quartz glass body with high accuracy and at low cost.

[0008]

In order to achieve the above object,
The present inventors have conducted intensive research, and as a result, a member serving as a mandrel for manufacturing quartz glass was made of a high-purity carbon fiber reinforced carbon composite material, a screw portion was formed at the end of the member, and the screw portion was used. It has been found that by joining members in series, a quartz glass manufacturing mandrel excellent in heat resistance, load resistance and workability can be obtained.

That is, the present invention that achieves the above object is
A mandrel used for manufacturing a synthetic quartz glass body, wherein the mandrel is formed of a member in which two or more cylindrical or cylindrical carbon fiber reinforced carbon composite material members are joined in series by screw portions. To a quartz glass manufacturing mandrel.

Further, the present inventors have found not only practicality excellent in joining by screws, but also improved the strength of the thread shape and the threaded portion (the portion corresponding to the thread / screw groove and its vicinity) itself, and The present invention has been completed by further study and trial and error on reinforcement of the joint portion and the like.

The present inventors adopt a "trapezoidal screw" (hereinafter, referred to as a "trapezoidal screw") having a "trapezoidal" cross-sectional shape for the shape of the threaded portion formed at the end of the mandrel member. As a result, it has been found that a mandrel for manufacturing a quartz glass body having high strength and excellent practicability has been realized, and a large synthetic quartz glass body can be manufactured more accurately and at low cost. In the present invention, it is possible to appropriately use a screw of various shapes other than a “triangular screw”, and among them, as a preferable one having excellent strength and high load resistance, in addition to the trapezoidal screw, a “square screw” and A “saw tooth screw” can be mentioned, and in practice, a trapezoidal screw can be selected as a more preferable one.

Further, the present inventors have found that by impregnating and / or coating the screw portion with carbon, the strength of the screw portion is further improved, and the screw portion can withstand a larger load. A mandrel whose body can be manufactured more accurately and at lower cost is made possible.

Further, the present inventors have found that by providing a reinforcing member on the outer periphery of the screw portion, the reinforcement of the joint portion of the screw portion can be further strengthened, and the contact area of the screw portion can be reduced and the thermal expansion of the screw portion can be suppressed. They have found that they can withstand a larger load, and have made possible a mandrel from which a large synthetic quartz glass body can be manufactured more accurately and at lower cost.

The mandrel for producing quartz glass of the present invention is a member in which two or more cylindrical or cylindrical members made of a carbon fiber reinforced carbon composite material (C / C composite) are screw-connected in series. Are generically referred to as a seed rod used in the shafting method, a substrate used in the external mounting method, and a mold used in the external mounting method.
(Of these, the “seed rod” and the “substrate” are so-called “target materials” for adhering quartz glass fine particles, and the “mold” refers to a quartz glass fine particle used for adhering. The base is extracted and inserted.)

The bulk density of the C / C composite is 1.5 g / cm ³ or more, the bending strength is 100 MPa or more,
The tensile strength is preferably in the range of 100 MPa or more. If it is less than the above range, sufficient strength cannot be obtained and the mandrel may be damaged or fall off, which is not preferable. This C / C composite is
For example, a prepreg is prepared by impregnating a carbon fiber with a pitch or a resin, and the prepreg is wound on a support and formed into a cylindrical shape, or a plurality of sheets are laminated and formed into a flat plate shape. Thereafter, a carbonization treatment, a densification treatment such as a pitch impregnation and sintering or a resin impregnation and sintering and a graphitization treatment are performed, and a halogen gas treatment is performed to obtain a highly purified product. C /
The impurities in the C composite consist of 1 pp of Na, K and Fe.
m or less. As a result, contamination by impurities can be reduced, and a high-purity synthetic quartz glass body can be obtained. For example, even when a quartz glass tube for an optical fiber preform is manufactured, a good loss of transmission characteristics is obtained. Optical fibers can be manufactured.

[0016]

FIG. 1 shows a quartz glass manufacturing mandrel in which a C / C composite member is joined by the trapezoidal screw. In FIG. 1, reference numeral 1 denotes a male screw on one of both ends. C / C composite rod provided with
Reference numeral 2 denotes a C / C composite rod provided with a female screw on one side of both ends, 3 denotes a male thread portion of the C / C composite rod 1, and 4 denotes a female thread portion of the C / C composite rod 2. Further, as shown in FIG.
When the carbon-impregnated and / or coated layer 5 is provided on the contact surface side of the thread portion of the composite rod, the strength of the thread portion is further improved, and the tensile strength of the rod having an outer diameter of 30 mm is reduced to a graphite rod. About four times as large as for that reason,
Even if the synthetic quartz glass body becomes large and long, or the diameter of the mandrel itself is reduced, the possibility of breakage at the screw portion is further reduced. Further, when a reinforcing member 6 made of a C / C composite is provided on the outer periphery of the threaded portion as shown in FIG. 3 to reinforce the threaded portion, the reinforcement of the threaded joint is further strengthened, and the thermal expansion of the threaded portion and the thread A decrease in the contact area can be suppressed, and higher load resistance can be ensured. The carbon-impregnated and / or coated layer refers to CVI treatment or CVD treatment, or resin impregnation / coating, curing,
A layer formed by impregnating or impregnating / covering a substance such as pyrolytic carbon or glassy carbon from the surface to the inside of the pores of the C / C composite by performing calcination, or pyrolytic carbon or glass A layer in which a substance such as carbonaceous carbon is coated on the surface, and a layer in which a substance such as pyrolytic carbon or glassy carbon is impregnated or impregnated and coated from the surface to the inside, and the surface is further coated with the substance, Say. In the above-mentioned "impregnation" and "coating", mechanical surface treatment and finishing as necessary before and after the step of forming these layers are generally performed industrially.

As described above, the mandrel for manufacturing quartz glass of the present invention has high heat resistance and load resistance.
Even when a large-sized porous quartz glass base material is produced, there is no center deviation during lifting and lowering or rotation during processing or transport, and a large synthetic quartz glass body can be manufactured with high accuracy and high productivity.
In particular, when the quartz glass manufacturing mandrel of the present invention is used as a mold inserted after removing the substrate from a porous quartz glass base material prepared by an external method, deterioration of the mandrel due to high heat or acid can be reduced. , Can extend the life of the mandrel itself. In addition, by using a substrate having excellent heat resistance and compressibility, such as ceramics, for forming the porous quartz glass base material, heat shrinkage during the preparation of the porous quartz glass base material can be prevented, and the base material is destroyed. Danger can be reduced.

When the mandrel of the present invention is used as a substrate or the like in an external method, the mandrel may be provided with a taper, and the mandrel may be vitrified in a vertical state with the larger taper facing downward. Thereby, shrinkage and movement of the base material which occurs when the porous quartz glass base material is turned into a transparent glass can be suppressed, and a quartz glass body with higher accuracy can be manufactured, so that cost reduction can be further developed.

Further, when the mandrel of the present invention is used as a transparent vitrifying mold or the like of a porous quartz glass base material, a pipe-shaped mandrel is formed by joining two or more cylindrical members in series. It may be formed. When a pipe-shaped mandrel is used, a high-temperature gas can flow through the hollow portion. For example, a porous quartz glass preform can be made by flowing a chlorine-containing gas (similar to the outer chlorine-containing atmosphere) also inside the mandrel. It is also possible to control the speed of the dehydration treatment and the vitrification of the transparent glass, for example, by allowing the dehydration to proceed from the inside.

The quartz glass fine particles used for producing the synthetic quartz glass body are produced by oxidizing or flame-hydrolyzing a volatile silicon compound in an oxyhydrogen flame burner. A porous quartz glass base material is formed by adhering the quartz glass fine particles to a columnar or cylindrical mandrel, and a large synthetic quartz glass body can be manufactured by heating the porous quartz glass base material to vitrify. . Examples of the method for forming the porous quartz glass base material include an axial attachment method and an external attachment method.
In particular, in the case of the external mounting method, either the horizontal type or the vertical type can be implemented. However, when manufacturing large and long synthetic quartz glass bodies, the vertical type is preferred. The volatile silicon compounds used are SiCl ₄ , SiCl ₃ (C
H ₃ ), SiMe (OCH ₃ ) ₃ , SiClF _{3 and the} like.

In order to perform dehydration treatment and sintering (transparent vitrification) of the porous quartz glass base material, a zone melt method in which the base material is held vertically and a heating zone is sequentially moved upward from below. In addition, a method in which an electric furnace having a large heating area is used and the method is performed in a stationary manner can be adopted. In particular,
The larger the quartz glass body to be manufactured, the greater the load during processing or transport, etc., so that the present invention is useful for the manufacture of large quartz glass bodies regardless of the shape and method of the electric furnace used. You can say that. FIG. 5 illustrates an embodiment in which the vitreous silica for manufacturing a quartz glass according to the present invention is used to form a transparent glass by a zone melt method. An example is shown in FIG.

[0022]

EXAMPLES The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

Example 1 A prepreg was prepared by impregnating a 6K plain weave cloth of carbon fiber (Torayca T-300) manufactured by Toray Industries Co., Ltd. with a phenol resin, cut into about 820 mm × 410 mm, and laminated.
Perform hot-press molding at 0 ° C to obtain about 820mm x 410
A compact having a size of mm × 35 mm was obtained. The molded body was heated to 800 ° C. in an electric furnace and heated to obtain a fired body. The fired body is densified by repeatedly performing pitch impregnation and firing, and then heat-treated at 2,000 ° C. to about 820 mm
A flat C / C composite of × 410 mm × 35 mm was obtained. When the physical properties of the C / C composite flat plate were measured, the bulk density was 1.62 g / cm ³ and the bending strength was 15
5 MPa and tensile strength of 220 MPa. From this flat plate, a cylindrical rod having a length of 800 mm and a diameter of 30 mm
Two rods were prepared, and of two rods, one end outer periphery was ground by 50 mm to form a trapezoidal male screw, and the other end inner periphery was ground to form a trapezoidal female screw, and high purity by halogen gas was used. After the chemical conversion treatment, the two were joined in series and joined to form a C having a length of 1550 mm and a diameter of 30 mm.
A / C composite mandrel was obtained. The obtained mandrel was attached to a tensile tester, and the breaking load was measured with a static tensile load at a transition speed of 0.5 mm / min. As a result, the thread fractured and the breaking load at that time was 14200 N
(Newton).

Further, for the remaining ten rods,
A trapezoidal male screw and a trapezoidal female screw were provided in the same manner as described above (here, one rod has only one male screw at one end, eight rods have one male screw at one end, and the other has a female screw at the other end). Only one female screw was provided on one end side of each of the rods), and then a high-purity treatment with a halogen gas was performed. Then, these ten rods are joined at nine places by male and female screws in the same manner as described above, and a length of 755
A C / C composite mandrel A having a diameter of 0 mm and a diameter of 30 mm was obtained.

Next, using an external method, gaseous silicon tetrachloride (SiCl ₄ ) is flame-hydrolyzed with an oxyhydrogen burner flame, and quartz glass fine particles are deposited on an alumina substrate. A porous quartz glass preform was obtained. An alumina substrate is extracted from the porous quartz glass base material, the C / C composite mandrel A is used as a mold and inserted into the extraction hole of the porous quartz glass base material, and a holding jig and the like are provided. The parent material was held vertically. In this state, the furnace was set in the upper part of the electric furnace, and the temperature of the furnace was raised to 1550 ° C., and then lowered into the furnace to form a transparent glass by a zone melt method. The obtained synthetic quartz glass hollow body did not have eccentricity, had good dimensional accuracy and good surface condition, and was also suitable as a tube for an optical fiber preform.

Example 2 As in Example 1, twelve cylindrical rods having a length of 800 mm and a diameter of 30 mm were produced. Of the two rods, the outer periphery of one end was ground by 50 mm to form a trapezoidal male screw, and the inner periphery of the other end was ground to form a trapezoidal female screw. The two rods having these threaded portions are subjected to a high-purity treatment with a halogen gas, and then put into a vapor deposition furnace, and impregnated with pyrolytic carbon by CVI treatment.
After coating, the two rods were connected in series and joined to obtain a C / C composite mandrel having a length of 1550 mm and a diameter of 30 mm. The obtained C / C composite mandrel was subjected to measurement of a breaking load by a static tensile load in the same manner as in Example 1. As a result, the thread was broken, and the breaking load at that time was 16,700 N.

Further, regarding the remaining ten rods,
After performing the purification treatment with halogen gas, the screw portion is impregnated and coated with pyrolytic carbon by the CVI treatment in the same manner as described above, and the trapezoidal male screw and the trapezoidal female screw are used in nine places as in the mandrel of Example 1. Were joined to obtain a C / C composite mandrel B having a length of 7550 mm and a diameter of 30 mm.

Next, the C / C composite mandrel B
Is used as a substrate, and gaseous silicon tetrachloride (SiCl ₄ ) is flame-hydrolyzed with an oxyhydrogen burner flame by an external method, and fine silica glass particles are deposited on a mandrel B to form a porous quartz having a weight of about 300 kg. A glass preform was obtained. It was conveyed in this state, set in a stationary electric furnace set at 1550 ° C., and vitrified. The obtained synthetic quartz glass hollow body did not have eccentricity, had good dimensional accuracy and good surface condition, and was also suitable as a tube for an optical fiber preform.

Example 3 As in Examples 1 and 2, the length was 800 mm and the diameter was 30 m.
12 cylindrical rods each having a diameter of m were prepared. Of the two rods, the outer circumference of one end was ground by 50 mm to obtain a trapezoidal male screw, and the other inner circumference was ground to obtain a trapezoidal female screw. . Next, the outer peripheral portion of the female screw portion is
mm and a length of 30 mm, a cylindrical C / C composite reinforcing member for reinforcing around the circumference is attached to the cut portion, and halogen gas is applied to the two rods formed with these threaded portions. , And then put into a vapor deposition furnace, impregnated and coated with pyrolytic carbon by CVI treatment, and connect the two rods in series to join them, length 1550 mm, diameter 30 mm C /
A C composite mandrel was obtained. The reinforcing member is formed by molding a carbon fiber (Torayca T-300) 12K filament manufactured by Toray Co., Ltd. into a cylindrical shape while impregnating a phenolic resin with a filament winding device, and repeating the pitch impregnation and firing of the molded body several times. After doing
Heat treatment was performed at 2000 ° C. Cut this cylinder-shaped product to a width of 20 mm, insert a metal jig into two parts inside,
When the tensile strength was measured by a method of pulling up and down using a tensile tester, there was a strength of 300 MPa. The reinforcing member is manufactured by processing the inner and outer diameters and the length so as to match the outer peripheral portion of the female screw portion of the C / C composite mandrel, and is fitted to the outer peripheral portion of the internal thread portion.
In the same manner as in Example 2, high purity treatment with halogen gas and impregnation and coating of pyrolytic carbon were performed. The obtained C / C composite mandrel was subjected to measurement of a breaking load by a static tensile load in the same manner as in Examples 1 and 2, and the thread was broken, and the breaking load at that time was 21000N.

Further, regarding the remaining ten rods,
After high purity treatment with halogen gas, the screw portion is impregnated and coated with pyrolytic carbon by CVI treatment in the same manner as above, and a trapezoidal male screw and cylindrical C / C
Nine places were joined together with the mandrel of Examples 1 and 2 using a trapezoidal female screw to which a composite reinforcing member was attached to obtain a C / C composite mandrel C having a length of 7550 mm and a diameter of 30 mm.

Next, the C / C composite mandrel C
As a seed rod, gaseous silicon tetrachloride (SiCl ₄ ) is flame-hydrolyzed with an oxyhydrogen burner flame by a shafting method, and quartz glass fine particles are grown on a mandrel C. A quartz glass base material was obtained. It was conveyed in this state, set in a stationary electric furnace set at 1550 ° C., and vitrified. The obtained synthetic quartz glass hollow body did not have eccentricity, had good dimensional accuracy and good surface condition, and was also suitable as a tube for an optical fiber preform.

Example 4 As in Examples 1 to 3, the length was 800 mm and the diameter was 30 m.
Twelve cylindrical rods having a diameter of m were prepared, and a trapezoidal male screw and a trapezoidal female screw were formed using the twelve rods in the same manner as in Example 3, and a C / C composite reinforcing member was formed on the outer peripheral portion of the female screw portion. After purifying all rods,
Impregnation / coating of pyrolytic carbon was carried out, and eleven places were joined in the same manner as the mandrel of Example 3 with a trapezoidal male screw and a trapezoidal female screw to which a reinforcing member was attached to form a C / C having a length of 9050 mm and a diameter of 30 mm A composite mandrel D was obtained.

Next, the C / C composite mandrel D
Is used as a mold to hold a porous quartz glass base material having a large outer diameter (that is, a thick wall) and a high density and a weight of about 900 kg,
It was transported, set in an electric furnace set at 1550 ° C., and vitrified transparently. The obtained synthetic quartz glass hollow body is
There was no eccentricity, the dimensional accuracy and the surface condition were good, and the tube was suitable as a tube for an optical fiber preform. From these handling conditions and the results of the measurement of the tensile strength in Example 3, it was confirmed that the mandrel in this example was capable of holding and transporting a porous quartz glass base material exceeding 1 t sufficiently. Was.

Comparative Example 1 Twelve cylindrical rods having a length of 800 mm and a diameter of 30 mm were made of high-purity isotropic high-density graphite (trade name: ISO-630, manufactured by Toyo Carbon Co., Ltd.). Were connected in series by a trapezoidal male screw and a trapezoidal female screw to obtain a high-purity isotropic high-density graphite mandrel having a length of 1550 mm and a diameter of 30 mm. The high-purity isotropic high-density graphite used had a bulk density of 1.82 g / cm ³ and a tensile strength of 53.9 M.
Pa and the ash content was 10 ppm or less. About the obtained mandrel, when the breaking load was measured by the static tensile load in the same manner as in Examples 1 to 3, the thread was broken,
The breaking load at that time was 3900N. Furthermore, after performing a high-purification treatment on the remaining 10 rods,
Nine points were joined by a trapezoidal male screw and a trapezoidal female screw to obtain a high-purity isotropic high-density graphite mandrel E having a length of 7550 mm and a diameter of 30 mm.

Next, using an external method, gaseous silicon tetrachloride (SiCl ₄ ) is flame-hydrolyzed with an oxyhydrogen burner flame, and quartz glass fine particles are deposited on an alumina substrate. A porous quartz glass preform was obtained. Alumina substrate is extracted from the porous quartz glass base material, and the high-purity isotropic high-density graphite mandrel E is inserted into the extraction hole of the porous quartz glass base material as a mold, and a holding jig is provided. The porous quartz glass preform was held vertically. In this state, it was set on the upper part of the electric furnace, the temperature of the furnace was raised to 1550 ° C., and then lowered into the furnace to attempt to vitrify by the zone melt method. The quartz glass base material fell off, and a transparent synthetic quartz glass hollow body could not be manufactured.

Comparative Example 2 In the same manner as in Examples 1 to 4, a length of 800 mm and a diameter of 30 mm
12 cylindrical rods were manufactured. Then, using two of the rods, a slit 10 is provided at the end of one cylindrical rod 7 and inserted into another cylindrical rod, as shown in FIG. 9 was inserted and the two rods were fixed to obtain a C / C composite mandrel having a length of 1550 mm and a diameter of 30 mm. About the obtained mandrel, when the breaking load by a static tensile load was measured similarly to Examples 1-3, the pin was broken, and the breaking load at that time was 9500N. Further, after the remaining 10 rods were subjected to a high-purification treatment, 9 places were joined together by pin fixing in the same manner as described above, and the length was 7550 m.
m, a C / C composite mandrel F having a diameter of 30 mm was obtained.

Next, the C / C composite mandrel F
Is used as a substrate, and gaseous silicon tetrachloride (SiCl ₄ ) is flame-hydrolyzed by an oxyhydrogen burner flame by an external method, and fine silica glass particles are deposited on a mandrel F to obtain a porous quartz having a weight of about 300 kg. When the glass preform was obtained, the mandrel was bent at the pin fixing portion, and the porous quartz glass preform was deformed. Therefore, a synthetic quartz glass hollow body with high accuracy could not be manufactured.

[0038]

Industrial Applicability The mandrel for manufacturing quartz glass of the present invention is a mandrel having good heat resistance, excellent load resistance, and excellent workability. The mandrel is made into a large mandrel to produce a large synthetic quartz glass body. Even when used, the mandrel is a mandrel that can be manufactured with high precision and at a low cost from a large, high-purity synthetic quartz glass body without breakage or slippage of the screw joint during manufacture.

[Brief description of the drawings]

FIG. 1 is a schematic view of a joint portion of a quartz glass manufacturing mandrel of the present invention.

FIG. 2 is a schematic illustration of a joint of a quartz glass manufacturing mandrel having a threaded layer with carbon impregnated and / or coated.

FIG. 3 is a schematic view of a joint portion of a quartz glass manufacturing mandrel in which a reinforcing member is formed on the outer periphery of a screw portion.

FIG. 4 is a schematic view of a joint portion of a quartz glass manufacturing mandrel connected in series by pin fixing.

FIG. 5 is a schematic diagram showing an embodiment in which the vitreous glass for producing quartz glass of the present invention is used to form a transparent glass by a zone melt method.

FIG. 6 is a schematic diagram showing an embodiment in which the vitreous silica for producing quartz glass of the present invention is used to make a transparent vitrification in a stationary electric furnace.

[Description of References] 1 rod (rod with male screw on one end side) 2 rod (rod with female screw on one end side) 3 male screw part of rod 1 4 female screw part of rod 2 5 carbon impregnation and // Coated layer 6 Reinforcing member made of C / C composite 7 Rod (rod with slit on one end side) 8 Pin insertion hole 9 Pin 10 Slit 11 Mandrel 12 Zone melt electric furnace 13 Pores Quartz glass base material 14 Heater 15 Stationary electric furnace

[Procedure amendment]

[Submission date] June 25, 2001 (2001.6.2)
5)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 6

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction contents]

[0004]

As described above, when a carbon-based compound is used as a material, it is very difficult to manufacture a mandrel having a length exceeding 1000 mm. Therefore, a plurality of members such as rods are joined in series. In some cases, the entire mandrel may be lengthened. As a method of lengthening by joining, a method of connecting a plurality of members using various various jigs, such as making a hole near the end of the member and locking it with a joining pin, has been made. A mandrel made of a carbon-based compound having a certain strength has also been made possible. However, with the recent increase in the size of optical fiber preforms and other materials, the synthesis of precursors (called porous quartz glass bodies and soot bodies) of the preforms and the sintering (transparent vitrification) of the precursors are called for. In this case, the load applied at the time increases, and in the case of locking by the conventional joining pin, a situation has occurred in which the pin cannot be withstand a large load and breaks. If the pins at the joints are damaged in this way, the joining of the mandrel will be incomplete, for example, when the porous quartz glass base material is sintered, it deforms and satisfies the desired shape. A quartz glass preform for optical fibers could not be obtained, or even a facility such as a heating furnace could be destroyed due to a drop of the porous quartz glass preform to be sintered. In other words, the extremely large porous quartz glass
The lack of a mandrel having sufficient strength to hold the material has been a limitation of producing a large synthetic quartz glass body with high accuracy and at low cost.
Therefore, in order to realize a longer mandrel while maintaining excellent heat resistance and load resistance, it is an important issue how to join mandrel members such as rods using any means. I was

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction contents]

The mandrel for producing quartz glass of the present invention is a member in which two or more cylindrical or cylindrical members made of a carbon fiber reinforced carbon composite material (C / C composite) are screw-connected in series. , the substrate for use with an external method to collectively mold elements for use in an external process. (Of these, the “ substrate” is a so-called “target material” for adhering quartz glass microparticles, and the “mold” refers to a substrate used for attaching and extracting quartz glass microparticles. Thing.)

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

The bulk density of the C / C composite is 1.5 g / cm ³ or more, the bending strength is 100 MPa or more,
The tensile strength is preferably in the range of 100 MPa or more. If it is less than the above range, sufficient strength cannot be obtained and the mandrel may be damaged or fall off, which is not preferable. This C / C composite is
For example, a plurality of prepregs in which a carbon fiber cloth is impregnated with a pitch or a resin are laminated and formed into a flat plate shape. afterwards,
Carbonization treatment by firing, impregnating the pitch or resin again
It is manufactured by performing a densification treatment such as firing and a graphitization treatment, and a high-purity treatment using a halogen gas. C /
The impurities in the C composite consist of 1 pp of Na, K and Fe.
m or less. As a result, contamination by impurities can be reduced, and a high-purity synthetic quartz glass body can be obtained. For example, even when a quartz glass tube for an optical fiber preform is manufactured, a good loss of transmission characteristics is obtained. Optical fibers can be manufactured.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

[0016]

FIG. 1 shows a quartz glass manufacturing mandrel in which a C / C composite member is joined by the trapezoidal screw. In FIG. 1, reference numeral 1 denotes a male screw on one of both ends. C / C composite rod provided with
Reference numeral 2 denotes a C / C composite rod provided with a female screw on one side of both ends, 3 denotes a male thread portion of the C / C composite rod 1, and 4 denotes a female thread portion of the C / C composite rod 2. Further, as shown in FIG.
When the carbon-impregnated and / or coated layer 5 is provided on the contact surface side of the thread portion of the composite rod, the strength of the thread portion is further improved, and the tensile strength of the rod having an outer diameter of 30 mm is reduced to a graphite rod. About four times as large as for that reason,
Even if the synthetic quartz glass body becomes large and long, or the diameter of the mandrel itself is reduced, the possibility of breakage at the screw portion is further reduced. Further, when a reinforcing member 6 made of a C / C composite is provided on the outer periphery of the threaded portion as shown in FIG. 3 to reinforce the threaded portion, the reinforcement of the threaded joint is further strengthened, and the thermal expansion of the threaded portion and the thread A decrease in the contact area can be suppressed, and higher load resistance can be ensured. Said
The C / C composite forming the reinforcing member is, for example, carbon
Cylindrical prepreg with fiber impregnated with pitch or resin
And formed into a cylindrical shape. Then before
Carbonization treatment, densification treatment, graphitization treatment, high-purification treatment
And carbon impregnation and / or coating
Manufactured with layers. The reinforcing member is also impregnated with the carbon.
And / or formed of uncoated C / C composite
You can also. Impregnated and / or coated with said carbon
The A layers, CVI treatment and / or CVD process using such hydrocarbon gas, or impregnation and coating of the resin, curing, by performing baking treatment or the like, the C / C composite, (i) CVI process From the surface to the pores
Part is impregnated and coated, or glassy by resin treatment, etc.
A layer formed by impregnating a substance such as carbon,
(Ii) pyrolytic carbon is coated on the surface by CVD treatment or
Material such as glassy carbon on the surface
(Iii) or a layer formed by being coated on
Pyrocarbon is impregnated from the surface into the pores by CVI treatment.
Materials such as glassy carbon which are coated or treated with resin
Quality is impregnated and the surface is thermally decomposed by CVD treatment
Carbon coated on the surface or glassy by resin treatment
Formed by coating the surface with a substance such as carbon
Say layer, the. In the above-mentioned "impregnation" and "coating", mechanical surface treatment or finishing is performed as necessary before and after the step of forming these layers, which is generally performed industrially.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

As described above, the mandrel for manufacturing quartz glass of the present invention has high heat resistance and load resistance.
Even when a large-sized porous quartz glass base material is produced, there is no center deviation during lifting and lowering or rotation during processing or transport, and a large synthetic quartz glass body can be manufactured with high accuracy and high productivity.
In addition, bases with excellent heat resistance and compressibility such as ceramics
A porous quartz glass preform is created on the body by an external method, and
After removing the body, the quartz glass manufacturing mandrel of the present invention is used as a mold body.
When inserted and used, it can be used to create a porous quartz glass preform.
Heat shrinkage of the substrate can be prevented, reducing the risk of breakage of the substrate.
In addition, the deterioration of the mandrel due to high heat or acid can be reduced.
The life of the device itself can be extended.

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction contents]

In order to perform dehydration treatment and sintering (transparent vitrification) of the porous quartz glass base material, a zone melt method in which the base material is held vertically and a heating zone is sequentially moved upward from below. In addition, a method in which an electric furnace having a large heating area is used and the method is performed in a stationary manner can be adopted. In particular,
The larger the size of the quartz glass body to be manufactured, the greater the load during processing or transportation, etc., so that the stationary heating method is useful regardless of the shape and method of the electric furnace used. FIG. 5 illustrates an embodiment in which the vitreous silica for manufacturing a quartz glass according to the present invention is used to form a transparent glass by a zone melt method. An example is shown in FIG. 5 and 6, 12 and 15 indicate electric furnaces, 11
Is a quartz glass manufacturing mandrel, 13 is a porous quartz glass mother
Material 14 is a heater.

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0023

[Correction method] Change

[Correction contents]

Example 1 A prepreg was manufactured by impregnating a 6K plain weave cloth of carbon fiber (Torayca T-300 ) manufactured by Toray Industries Co., Ltd. with a phenol resin, cut into about 820 mm × 410 mm, and laminated.
Performed hot press molding at 160 ° C, about 820mm x 4
A compact having a size of 10 mm × 35 mm was obtained. The molded body was heated to 800 ° C. in an electric furnace and heated to obtain a fired body. The fired body is densified by repeatedly performing pitch impregnation and firing, and then heat-treated at 2,000 ° C. to about 820 m
A flat C / C composite of mx 410 mm x 35 mm was obtained. When the physical properties of the C / C composite plate were measured, the bulk density was 1.62 g / cm ³ and the bending strength was 1
It was 55 MPa and the tensile strength was 220 MPa. Twelve cylindrical rods having a length of 800 mm and a diameter of 30 mm were prepared from this flat plate. Of the two rods, one end outer periphery was ground to a trapezoidal male screw from the end face to a length of 50 mm from the end face by grinding , and another rod was formed. The inner circumference of the end is made into a trapezoidal female screw by grinding, and after purifying with a halogen gas, the two are connected in series and joined to form a length of 155.
A C / C composite mandrel having a diameter of 0 mm and a diameter of 30 mm was obtained. The obtained mandrel was attached to a tensile tester, and the breaking load was measured with a static tensile load at a transition speed of 0.5 mm / min. As a result, the thread was broken, and the breaking load at that time was 14,200 N (Newton).

[Procedure amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction contents]

Example 2 As in Example 1, twelve cylindrical rods having a length of 800 mm and a diameter of 30 mm were produced. For them two rods, 50 mm length from the end face by grinding the one end portion outer periphery
While a trapezoidal male screw was used, the inside of the other end was ground to form a trapezoidal female screw. The two rods on which these threaded portions are formed are subjected to a high-purity treatment with a halogen gas, then put into a vapor deposition furnace, and impregnated and coated with pyrolytic carbon by CVI treatment. The rods were connected in series and joined to obtain a C / C composite mandrel having a length of 1550 mm and a diameter of 30 mm. The obtained C / C composite mandrel was subjected to measurement of a breaking load by a static tensile load in the same manner as in Example 1. As a result, the thread was broken, and the breaking load at that time was 16700 N.
Met.

[Procedure amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0029

[Correction method] Change

[Correction contents]

Example 3 As in Examples 1 and 2, the length was 800 mm and the diameter was 30 m.
12 cylindrical rods having a diameter of m were prepared, and two rods of which were ground 50 m from the end face by grinding the outer periphery of one end.
While a trapezoidal male screw was formed up to the length of m, the inner circumference of the other end was ground to form a trapezoidal female screw. Next, the outer peripheral portion of the female screw portion was cut by a depth of 1 mm and a length of 30 mm . This is the cutting portion, because attaching the C / C composite-made reinforcing member of cylindrical shape for reinforcing the circumferential
It is . The two rods on which these threaded portions are formed are subjected to a high-purity treatment with a halogen gas, then put into a vapor deposition furnace, and impregnated and coated with pyrolytic carbon by CVI treatment. Rods are connected in series and joined to form a 1550 mm long, 30 mm diameter C /
A C composite mandrel was obtained. The reinforcing member is
A carbon fiber (Treca T-300) 12K filament manufactured by Co., Ltd. is formed into a cylinder shape while impregnating a phenolic resin with a filament winding device, and the molded product is densified by repeating pitch impregnation and firing several times. , 2000 ° C. This cylinder-shaped product was cut into a width of 20 mm, and a metal jig divided into two was inserted therein. The tensile strength was measured by a method of pulling up and down using a tensile tester. The tensile strength was 300 MPa. this
The reinforcing member is provided around the internal thread of the C / C composite mandrel.
The inner and outer diameters and lengths are machined to fit the cutting part, as shown in Fig. 3.
As described above, it was fitted to the cut portion on the outer periphery of the female screw portion . The supplement
The strong member was further subjected to high-purity treatment with a halogen gas and impregnation / coating with pyrolytic carbon, as in Example 2. The obtained C / C composite mandrel was subjected to measurement of a breaking load by a static tensile load in the same manner as in Examples 1 and 2, and the thread was broken, and the breaking load at that time was 21000N.

[Procedure amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction contents]

Next, the C / C composite mandrel D
Is used as a mold to hold a porous quartz glass base material having a large outer diameter (that is, a thick wall) and a high density and a weight of about 900 kg,
It was transported, set in an electric furnace set at 1550 ° C., and vitrified transparently. The obtained synthetic quartz glass hollow body is
There was no eccentricity, the dimensional accuracy and the surface condition were good, and the tube was suitable as a tube for an optical fiber preform. From the handling conditions and the measurement results of the tensile strength in Example 3, the mandrel in this example was 900 kg.
Holding the porous quartz glass preform say, it was confirmed transported like is sufficient available.

[Procedure amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction contents]

[0038]

Industrial Applicability The mandrel for manufacturing quartz glass of the present invention is a mandrel having good heat resistance, excellent load resistance and workability, and is used, for example , for manufacturing large synthetic quartz glass bodies exceeding 1 t. This is a mandrel that can be manufactured with high precision and at a low cost from a large, high-purity synthetic quartz glass body without breakage or slippage of the screw joint during manufacturing.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Atsuyuki Shimada 88, Kawakubo, Kanaya, Tamura-cho, Koriyama-shi, Fukushima Prefecture Inside the Koriyama Plant, Shin-Etsu Quartz Co., Ltd. Toyo Carbon Co., Ltd. F term (reference) 4G014 AH15 4G032 AA09 AA14 AA52 BA00 GA20 4G062 AA07 BB02 CC07 NN01

Claims (6)

[Claims] 1. A mandrel for use in the production of a synthetic quartz glass body, wherein the mandrel is formed from a member in which two or more cylindrical or cylindrical carbon fiber reinforced carbon composite material members are joined in series by a screw portion. A quartz glass manufacturing mandrel characterized by the following. 2. A quartz glass manufacturing mandrel according to claim 1, wherein the screw portion for joining the members made of carbon fiber reinforced carbon composite material is a trapezoidal screw. 3. The mandrel for quartz glass production according to claim 1, wherein carbon is impregnated and / or coated on the thread portion. 4. A reinforcing member made of carbon fiber reinforced carbon composite material is provided on an outer periphery of the screw portion.
4. The mandrel for manufacturing quartz glass according to any one of items 1 to 3. 5. The quartz glass manufacturing mandrel according to claim 1, wherein the mandrel is made of a porous quartz glass base material obtained by an external method and then inserted. For manufacturing quartz glass. 6. The quartz glass producing mandrel according to claim 1, wherein the quartz glass producing mandrel is a seed rod for attaching a shaft or a base for external attachment.