JPS61232229A - Production of fluorine-doped high-purity quartz glass pipe - Google Patents

Abstract

PURPOSE:To produce the titled quartz pipe having smooth and high-accuracy inner and outer surfaces without causing cracking in the pipe, by depositing pure silica glass soot by VAD process, preliminarily sintering the deposited soot to form a porous intermediate, boring the intermediate and melting and integrating the bored intermediate. CONSTITUTION:Deposited pure silica glass soot is preliminarily sintered to obtain a porous intermediate, which is bored and integrated by melting in a furnace. The preliminary sintering or melt integration is carried out in an atmosphere (e.g. He) added at least temporarily with fluorine. It is preferable to grind the outer surface of the above porous intermediate before or after the boring process to improve the dimensional accuracy of the produced glass pipe.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for manufacturing a high-purity quartz glass pipe doped with fluorine. The present invention relates to a method for obtaining the above-mentioned glass pipe of high quality, which has smooth inner and outer surfaces and is free from cracks while achieving high dimensional accuracy.

[Conventional technology]

Conventionally, the VAD method (vapor phase axis attachment method) was used to manufacture fluorine-doped high purity quartz glass pipes that could be used as base materials for optical fibers, for example, by placing glass raw materials in a flame. The fine particulate glass (nuss) obtained by introducing K is deposited to form a glass fine particle deposit, and the deposit is heated while adding fluorine to dehydrate and sinter to form a glass rond, followed by glass grinding. There is a method in which a glass pipe is obtained by drilling a hole in the glass iron using a machine or the like.

[Problem that the invention seeks to solve]

However, the above-mentioned method has the following problems: 1) cracks tend to form from the inner surface when drilling holes, and 2) it is difficult to achieve precision when drilling holes. Special K 2) The reason why it is difficult to obtain precision when drilling holes is that the outer circumference of the sintered glass rod is not perfectly cylindrical, so it is difficult to make the holes concentric when installing the machine, and the setting of the drill position is also difficult. For example, the accuracy corresponds directly to the eccentricity of the pipe hole.

In order to solve the problem of cracking in 1) above, there is a method of grinding the outer circumference of the glass rod to make it into a perfect cylinder shape before drilling the hole. When used as a base material for a fiber, cracks occur inside the fiber, causing bubbles to form and deteriorating the properties of the fiber.

As described above, it is still difficult to manufacture a glass pipe with high precision and no cracks using conventional methods.

An object of the present invention is to solve the above-mentioned problems and provide a method for obtaining a fluorine-doped high-purity quartz glass pipe with smooth inner and outer surfaces and high dimensional accuracy without causing cracks in the pipe. There are k.

[Means for solving the problem] The present invention involves forming a pure silica glass fine particle deposit by a VAD method, pre-sintering the deposit to obtain a porous intermediate, and The holes are processed and then melted and integrated in a heating furnace, and the atmosphere during the temporary sintering or the melting and integration is made to contain fluorine for at least a period of time. This is a method for manufacturing nine high-purity quartz glass pipes.

Particularly preferred embodiments of the present invention include the methods described above.

The present invention will be explained in detail below.

As a result of various studies and discussions on the problems of the conventional method, the present inventors found that the bulk density of the glass microspore deposit obtained by the VAD method was in the range of PiO,15Ii/- to 0.61/-. Because it has a distribution in the radial direction, it is very brittle, and because it is subjected to thermal history during deposition, it retains distortion, and a small impact can cause cracks and ruptures, making it difficult to grind.
The bulk density of the deposited body (porous body) can be easily ground,
I came up with the idea of increasing the height to a level that does not cause cracks.

In order to increase the bulk density of the above-described porous body, the present invention provides K,
By pre-sintering the porous body, a porous intermediate body is obtained. The bulk density of the porous intermediate is preferably 0.7117 or more so that it can be easily ground and cracks do not occur.

In addition, if dehydration is required, if the bulk density of the porous material is too high, dehydration will take a long time, so in this case, the bulk density should be set to III/- or less. preferable.

In the pre-sintering method of the present invention, a pure glass fine particle deposit body prepared by the VAD method is heated at a temperature of 1200C to 14C.
Heating was performed for about 1 hour at 00c in a He 2 atmosphere. When fluorine is added at the same time, a fluorine compound such as carbon fluoride gas, sulfur fluoride gas, silicon fluoride, fluorine, or halogen fluoride is added to the He 2 gas mixture.

As described above, a porous intermediate 1 as shown in FIG.
can be obtained. Note that 2 in FIG. 1 is a support rod.

For drilling holes in the grinding process, #: can be used by attaching a drill of the required diameter to a drill press commonly used for machining. Preferably, a grinding blade of a grindstone layer, particularly preferably a grinding blade of an industrial diamond grindstone layer, is used to achieve highly accurate grinding.

Both the feeding type and the lathe type can be used for the outer circumference grinding process, but the latter is used when the cylindrical shape of the outer surface and the concentricity and straightness of the hole are required.

Next, an example in which a lathe is used for the above-described grinding process will be specifically described with reference to the drawings.

As shown in FIG. 2, the support rod 2 of the porous intermediate body 1 is gripped by the chuck 3 on one side of the lathe. Next, at the ninth point when the main axis of the lathe and the central axis of the porous intermediate body 1 are aligned, a part of the support rod 2 is heated and softened using an oxyhydrogen burner 4 to adjust the position of the porous intermediate body 1. Next, the rod-shaped grinding blade 5 made of a diamond grindstone is attached to the other chuck or grinding blade fixing base 6 of the lathe, and the rod-shaped grinding blade 5 is introduced into the rotating porous intermediate body 10. , open a hole. Incidentally, 1' indicates the grinding debris, and the arrows indicate the direction of rotation and the direction of approach.

As shown in FIG. 3, the outer circumferential grinding is carried out by installing a porous intermediate support reamer 7 on a grinding blade fixing table 6, which supports the porous intermediate 1 from both sides, and 1 is rotated in the direction of the arrow, and its outer periphery is ground by a grinder 8 rotating in the direction of the arrow. 1/2 is grinding waste.

The pipe-shaped porous intermediate obtained by the above steps is placed in a furnace and melted and integrated in an atmosphere of Ha gas or a fluorine compound added thereto, as in the case of preliminary sintering. Maku,
If it is necessary to perform dehydration in an atmosphere containing chlorine gas, treatment is performed in an atmosphere containing He gas and chlorine gas in a furnace at 1000C to 1100C for about 1 hour before melting and integration.

In this way, by grinding into a glass pipe shape at the porous intermediate stage before transparent vitrification, the dimensional error during processing can be reduced by the fifth root of the relative bulk density when transparent vitrification is achieved. . Therefore, even with the conventional method of processing the transparent glass pipe after forming it, the dimensional accuracy of the glass pipe can be improved.

〔Example〕

Example 1 By VAD method) a! By adding silicon tetrachloride to a hydrogen flame, the length is 60 mm and the average bulk density is approximately 0.21.9/cI! A pure silica glass fine particle deposit body of I was prepared.

Next, this deposited body was heated to a heating furnace of JHθ5 J7 m1in.
Flowing eC1250cc/win, dehydration was performed at a temperature of 1050C1 with a descending rate of 5cm/win in a dead atmosphere, and the atmosphere was further changed to Ha 5 J3/win #13160.
-2 J/1ain #5 with furnace temperature as 155DC
Temporary sintering was performed by lowering the temperature at tm/m1n. As a result of the above, the outer diameter is 6.5 to 7.5cIII, and the length is approximately 42cnR1 flat 2
A porous body having an average bulk density of about 0.8777an3 was obtained. This porous intermediate body is mounted on a horizontal lathe as shown in Fig. 2, and the chuck 3 of the lathe is rotated while the porous body is rotated.
A part of the support rod 2 held by the support rod 2 was heated with an oxyhydrogen burner 4 to center the porous intermediate body 1. The rotation of the chuck 230 fixing the porous intermediate body 1 is stopped, and the outer diameter of the chuck 6 is 811111. A cylindrical diamond grindstone 5 having an outer diameter of 9 mm and a length of 100 mm was attached to the tip of a pipe-shaped shank having a length of 453 cm, and was rotated at 240 rpm to drill and grind the porous intermediate body 1. Next, remove the grinding blade 5 from the chuck 6 and attach the reamer 7 to it as shown in Fig. 3, thereby suppressing the wobbling of the porous body.
Outer diameter 127131 attached to the grinding blade stand of a lathe. Thickness 1
A 9tm disc-shaped grinder 8 was rotated at 45°rpm to grind the outer peripheral surface of the porous intermediate body 1 to an outer diameter of 64.0.
±0°2n. The pipe-shaped porous intermediate obtained above was heated with He 10 #'win8F60.4137
Transparent vitrification was performed by passing the sample through a furnace at a temperature of 1650 C' at a descending speed of 4 m/Win in an atmosphere of 50 min. Through the above process, a high-quality glass pipe with an outer diameter of 45.2±0°03ICI, an inner diameter of 5.9±0°03i11, a uniform wall thickness, a total length of 303, smooth on both the inner and outer surfaces, and without any air bubbles was obtained. . Also, the relative refractive index difference with pure silica glass is 0.3
OH group content measured by infrared absorption method in % 1d
O, 1 ppm+ or less, which has good characteristics for the original fiber base material.

Comparative Example 1 A glass particle deposit similar to that in Example 1 was exploded, and the deposit was dehydrated, fluoridated, and made transparent under the same conditions as in Example to produce a glass pipe with an outer diameter of about 460 mm and a total length of 30 mm. I got it.

Next, this was mounted on the same horizontal lathe as in Example 1, and an attempt was made to open a hole using the same method as in Example 1. However, during grinding, an umbrella-shaped crack of several depths was found on the inner surface of the pipe and the inner surface of the pipe, extending over the entire length. Occurred. Subsequently, the outer periphery was ground to make the outer diameter uniform in the same manner as in the example, but the wall thickness varied by 0.2111. The dimensional accuracy was poor.

〔Effect of the invention〕

As described above, the method of the present invention is more effective in that it is possible to obtain glass pipes of better quality and higher dimensional accuracy than the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a pre-sintered porous intermediate, FIG. 2 is a diagram showing hole drilling with a horizontal lathe, and FIG. 3 is a diagram showing outer periphery grinding with a horizontal lathe.

Claims (2)

[Claims] (1) A pure silica glass fine particle deposit is formed by the VAD method, the deposit is pre-sintered to obtain a porous intermediate, the porous intermediate is punched, and then placed in a heating furnace. A method for producing a high-purity quartz glass pipe doped with fluorine, characterized in that the atmosphere during the temporary sintering or the melting and integration includes fluorine at least temporarily. (2) A method for manufacturing a high-purity fluorine-doped quartz glass pipe as set forth in claim (1), wherein the porous intermediate is subjected to peripheral grinding before or after drilling.