JP2006193369A - Method and apparatus for processing quartz glass bar and carbon tool used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for processing a quartz glass bar and a carbon tool used for the same which can easily process the quartz glass bar at a low cost. <P>SOLUTION: The method for processing a quartz glass bar is characterized by holding a quartz glass bar 2 with one chuck 1a of a glass lathe and a carbon tool 3 with the other chuck 2b, heating the quartz glass bar 2 with an oxyhydrogen gas burner 4, and moving a lathe head to push-form the softened portion of the quartz glass bar 2 to the carbon tool 3, wherein a hemispherical protrusion is formed by pushing the softened portion. The quartz glass bar 2 can be automatically processed by automatically controlling the regulation of the movement to a predetermined position relative to the oxyhydrogen gas burner 4 and the oxygen and hydrogen gas flow rates, the temperature of the heated portion of the quartz glass bar 2, the relative movement of the carbon tool 3 toward the quartz glass bar 2, and the like, according to a preliminarily programmed condition. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to the production of a quartz glass preform for optical fibers, and more particularly to a method and apparatus for processing a quartz glass rod, and a carbon jig used therefor.

  The silica glass base material for optical fibers is a porous soot produced by hydrolyzing glass raw materials such as silicon tetrachloride in an oxyhydrogen flame, and depositing and growing the generated glass particles on a rotating quartz glass rod. Hereinafter, it is simply referred to as soot), and is further dehydrated and sintered to form a transparent glass.

The soot is handled and transferred to a sintering machine, where it is processed into a transparent vitrification, etc., but during handling and transfer, the soot is brittle and easily damaged, so the portion of the quartz glass rod on which no soot is deposited Grasping with
Conventionally, in order to facilitate the handling and transfer of soot, it has been practiced to provide protrusions or recesses at two locations near the end of the quartz glass rod.

  Conventionally, to provide protrusions or recesses in a quartz glass rod, hold both ends of the quartz glass rod with a glass lathe, heat and soften the part to be processed with an oxyhydrogen gas burner, and move and press the lathe head inward. The softened portion is swelled into a spherical shape, and the heated portion is further moved and the same operation is repeated to form several spherical portions. Thereafter, a part of the formed spherical portion is ground and processed into a hemispherical shape with a cylindrical grinder, and the ground portion is further flame-polished with an oxyhydrogen flame to be transparent.

In addition, there is a method of forming a quartz glass rod by heating and stretching with a glass lathe. For example, the protrusion can be formed by preparing a quartz glass rod having a slightly larger diameter and heating and sequentially stretching the other portions so as to leave the protrusion formation portion. In addition, it can be formed by grinding with a cylindrical grinder (see Patent Document 1).
Further, there is a method in which a preliminarily processed conveying member is inserted into a quartz glass rod and pinned to form a protrusion (see Patent Document 2).
JP 7-41330 A JP 2001-172039 A

As described above, each method requires a quartz glass rod having a large diameter and a pre-processed conveying member, or requires a plurality of processing steps to form a spherical portion, resulting in high manufacturing costs. there were.
Accordingly, an object of the present invention is to provide a method and apparatus for processing a quartz glass rod, which can easily process the quartz glass rod at low cost, and a carbon jig used therefor.

In the method for processing a quartz glass rod of the present invention, the quartz glass rod is held by one chuck of the glass lathe, the carbon jig is held by the other chuck, the quartz glass rod is heated by an oxyhydrogen gas burner, and the lathe head is moved. A carbon jig is pressed against the softened portion of the quartz glass rod, and a hemispherical protrusion is formed by pressing the softened portion.
Pre-programmed conditions such as movement to the specified position with respect to the oxyhydrogen gas burner and adjustment of the oxygen / hydrogen gas flow rate, the temperature of the heated portion of the quartz glass rod, the relative movement of the carbon jig toward the quartz glass rod, etc. The quartz glass rod can be processed automatically.

The quartz glass rod processing apparatus of the present invention is an apparatus for processing a quartz glass rod with a glass lathe, a burner positioning linear scale for moving the oxyhydrogen gas burner to a predetermined position, and oxygen / hydrogen gas to the oxyhydrogen gas burner. It is characterized by comprising a flow rate controller for adjusting the flow rate and a carbon jig for forming a quartz glass rod. An external shape measuring device may be provided to measure the outer diameter of the quartz glass rod.
Furthermore, the processing apparatus for the quartz glass rod of the present invention includes a control device that automatically controls the quartz glass rod by controlling according to a preset program.

  The carbon jig of the present invention has a cylindrical hole into which the quartz glass rod is inserted, and the cylindrical carbon jig is pressed from the axial direction to the heating / softening portion of the quartz glass rod, A hemispherical projection is formed, and an air vent hole is preferably provided in the back of the hole.

  According to the present invention, a projection suitable for handling and transport can be easily and reproducibly formed on a quartz glass rod, and further, it can be processed in a short time and at low cost by automation.

In the method for processing a quartz glass rod of the present invention, a hemispherical protrusion can be easily and automatically formed by heating and softening a predetermined position of the quartz glass rod and pressing a carbon jig. The reason for using a carbon jig to form the protrusions is:
The mold is easy to process, the glass and the jig are not fused, the contact surface is smooth, and polishing is not required. For this reason, it is preferable that the carbon material used for the carbon jig has as low an impurity content as possible. Specifically, it is preferable that the content of impurities other than carbon is 1% by weight or less.
In addition, the reason for forming the protrusions in a hemispherical shape is to make the product effective part as long as possible in the process.

  Hereinafter, although the processing method of the quartz glass rod of this invention is demonstrated in detail, it is not limited to these, Various aspects are possible.

Example 1
The quartz glass rod 2 having an outer diameter of 40 mm was held by the fixed side chuck 1a of the glass lathe shown in FIG. 1, and the carbon jig 3 was held by the movable side chuck 1b. The burner 4 is attached to the burner positioning linear scale 6 at a distance of 105 mm between its tip and the center of the quartz glass rod 2, and the motor 8 is driven by the output of the rotary encoder 7. The movement distance of the burner 4 is controlled. The burner 4 was supplied with hydrogen as the combustion gas and oxygen as the auxiliary combustion gas, and the flow rate was adjusted by the flow rate regulator 10.

In the processing of the quartz glass rod 2, the heating position of the burner 4 is determined by the diameter size of the quartz glass rod 2 measured by an outer diameter measuring device (not shown), the amount of gas supplied to the burner 4, the lathe head 11 It is controlled by the control device 12 according to preprogrammed conditions such as the moving distance and its timing.
The processing procedure for the quartz glass rod is shown below.

Procedure 1;
First, as shown in FIG. 2 (a), the free end side of the quartz glass rod 2 gripped by one chuck 1a is made into the hole (depth L) of the carbon jig 3 gripped by the other chuck 1b. The burner 4 is moved to a predetermined position while rotating the quartz glass rod 2 around its axis, and heated and softened.

Step 2;
Next, when the heating portion of the quartz glass rod 2 is softened, the burner 4 is released to the left in the drawing, and the carbon jig 3 is pressed and molded toward the softening portion by a predetermined distance. Note that the molding may be started when heated for a predetermined time or when a predetermined temperature is reached by a temperature sensor. As a result, as shown in FIG. 2B, the softened portion is deformed and a hemispherical first protrusion is formed at a position L from the free end of the quartz glass rod 2.

Step 3;
Next, a second protrusion is formed at a position away from the first protrusion by a distance A. To this end, the quartz glass rod 2 is detached from the hole of the carbon jig 3 at one end, and the carbon jig 3 After inserting the carbon piece 5 so that the depth of the hole becomes B (see FIG. 2 (c)), the quartz glass rod 2 is inserted again, and the first protrusion is A position at a distance A toward the tip is heated. When the heating portion is softened, the burner 4 is released, and the carbon jig 3 is pressed and molded toward the softened portion by a predetermined distance. Thereby, a hemispherical second protrusion is formed at a position away from the first protrusion by a distance A.
FIG. 2D shows a state (finished shape) in which the quartz glass rod 2 is detached from the hole of the carbon jig 3 after the second protrusion is formed. The positions of the first and second protrusions can be changed depending on the depth of the hole of the carbon jig 3.
In this way, a necessary number of hemispherical protrusions that do not require grinding can be automatically and easily formed at a desired position of the quartz glass rod.

(Comparative Example 1)
Both ends of a quartz glass rod having an outer diameter of 40 mm were held by a chuck and set on a glass lathe. When the burner was moved to a predetermined projection formation position and heated and softened, one lathe head was moved inward to compress the softened portion to form a spherical first projection. Further, the same operation was repeated while changing the heating position to form a second protrusion. During this time, the position of the burner, adjustment of the gas flow rate, movement of the lathe head, etc. were performed while the operator visually observed the softened state and shape of the glass.
Next, remove the quartz glass rod from the glass lathe, set it on a cylindrical grinder, grind the half of the spherical part, finish the protrusions into a hemisphere, and further polish the roughened surface with an oxyhydrogen burner, transparent (See FIG. 3).

  According to the present invention, it contributes to the reduction of the processing cost of the quartz glass rod.

It is the schematic which shows an example of the processing apparatus used in the Example. (A)-(d) is a schematic sectional drawing explaining the procedure which forms a projection part in a quartz glass stick | rod by the Example of this invention. It is the schematic explaining the procedure which forms a projection part in a quartz glass rod by the conventional method.

Explanation of symbols

1a, 1b ... chuck,
2 ... Quartz glass rod,
3 …… Carbon jig,
4 ... Burna,
5 ... top,
6: Linear scale for burner positioning,
7 …… Rotary encoder,
8 …… Motor,
9 …… Chain,
10 …… Flow regulator,
11 ... Lathe head,
12: Control device.

Claims (10)

Hold the quartz glass rod with one chuck of the glass lathe and the carbon jig with the other chuck, heat the quartz glass rod with the oxyhydrogen gas burner, move the lathe head, and fix the softened part of the quartz glass rod to the carbon jig A method for processing a quartz glass rod, wherein the method is formed by pressing to a quartz glass rod. The method for processing a quartz glass rod according to claim 1, wherein the carbon jig is formed of a carbon material having an impurity content other than carbon of 1 wt% or less. The method for processing a quartz glass rod according to claim 1 or 2, wherein a hemispherical protrusion is formed by forming the softened portion. Pre-programmed conditions such as movement to the specified position with respect to the oxyhydrogen gas burner and adjustment of the oxygen / hydrogen gas flow rate, the temperature of the heated portion of the quartz glass rod, the relative movement of the carbon jig toward the quartz glass rod, etc. The method for processing a quartz glass rod according to any one of claims 1 to 3, wherein the quartz glass rod is automatically processed according to the above, and the quartz glass rod is automatically processed. An apparatus for processing a quartz glass rod by a glass lathe, a linear scale for positioning an oxyhydrogen gas burner to a predetermined position, a flow controller for adjusting an oxygen / hydrogen gas flow rate to the oxyhydrogen gas burner, and quartz glass An apparatus for processing a quartz glass rod, comprising a carbon jig for forming the rod. The quartz glass rod processing apparatus according to claim 5, wherein the carbon jig is formed of a carbon material having an impurity content other than carbon of 1 wt% or less. 6. The processing apparatus for a quartz glass rod according to claim 5, further comprising an external shape measuring device for measuring the outer diameter of the quartz glass rod. The processing apparatus for a quartz glass rod according to any one of claims 5 to 7, further comprising a control device that automatically controls the quartz glass rod by controlling according to a preset program. A carbon jig characterized in that a cylindrical carbon jig is pressed against a heating / softening portion of a quartz glass rod to form a hemispherical protrusion on the quartz glass rod. The carbon jig according to claim 9, wherein an air vent hole is provided at the back of the hole portion into which the quartz glass rod is inserted.

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