JP2003048732A - Method for forming precision glass tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of forming precision glass tubes which is capable of forming a variety of the precision glass tubes different in the ratio of the internal to the external dimensions from a preform glass tube from the preform glass tube consisting of glass or crystallized glass of prescribed dimensions. SOLUTION: This method of forming the precision glass tube 20 comprises gripping the preform glass tube 1 consisting of the glass or crystallized glass and having the ratio of the internal to the external dimensions within a prescribed ratio in a gripping section 2a of feeding means 2 and feeding the preform glass tube into a heating furnace 4, by which the preform glass tube 1 is heated to the prescribed temperature at which the minimum viscosity thereof attains 10<3> to 10<6> Pa.s, then stretching the lower part of the preform glass tube 1 by pulling means, thereby forming the precision glass tube 20 having the ratio of the internal to the inner and extern dimensions of the prescribed range varying in the ratio of the internal to the external dimensions from the preform glass tube 1.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for molding a precision glass tube.

[0002]

2. Description of the Related Art In recent years, with the development of optical communication technology, in order to hold and fix optical fibers, lenses, etc. in optical devices, optical connectors, etc., transparency, low expansion, mass producibility, and appropriate polishing properties are achieved. Many types of precision glass tubes are used that have the advantages of.

In general, the inner and outer dimensions of a precision glass tube obtained by drawing a base material glass tube, that is, the inner dimensions such as the inner diameter and the outer dimensions such as the outer diameter, are the same as the inner and outer dimensions of the base material glass tube. It is determined by the reduction ratio. For example, JP-A-6-
No. 94944 describes that the inner-outer dimension ratio of a base glass tube and the inner-outer dimension ratio of a glass tube stretch-molded therefrom are the same.

[0004]

However, in the conventional molding technique as described above, when a precision glass tube having desired inner and outer dimensions is manufactured, it is necessary to individually manufacture a dedicated base material glass tube. . Therefore, in order to manufacture various types of precision glass tubes with different inner and outer dimension ratios, it is necessary to design and manufacture the base material glass tube in consideration of the reduction ratio for each product type, which causes a problem that the manufacturing period of the precision glass tube becomes long. is there.

Therefore, when shortening the manufacturing period of the precision glass tube, it is necessary to always prepare a dedicated base material glass tube for each type of precision glass tube, which causes a problem that the manufacturing cost becomes very high. is there.

The present invention solves the above-mentioned problems and can form a variety of precision glass tubes having a different inner / outer dimension ratio from the base material glass tube made of glass or crystallized glass having a predetermined size. It is an object of the present invention to provide a possible method for forming a precision glass tube.

[0007]

A method for forming a precision glass tube according to the present invention is such that a preform glass tube made of glass or crystallized glass having an inside-outside dimension ratio within a predetermined range is held in a holding portion of a feeding means, By sending the base material glass tube to a heating furnace, the minimum viscosity of the base material glass tube is 10 ³ to 10 ⁶ P
By heating to a predetermined temperature of a · s and stretching the lower part of the base material glass tube with a tension means, a precision glass tube having a desired range of inner and outer dimensions different from the base material glass tube is formed. It is characterized by

The minimum viscosity of the base glass tube in the heating furnace is 10
³If it is less than Pa · s, the glass tube during bending may bend.
You can pull straight through a precision glass tube of a certain size
Since it bends without being used, it cannot be used. On the other hand, the lowest viscosity
Degree 10⁶If it exceeds Pa · s, stretching is performed as before.
It is not possible to control the reduction ratio of the precision glass tube during shaping
As well as the rheology of the glass tube during stretch forming.
Behavior, it is very difficult to stretch when trying to increase the pulling speed.
Requires a large amount of force, making it difficult to manufacture the corresponding molding equipment.
Not only is it difficult, but it is stretched due to tensile stress during molding.
The glass tube in the shape often breaks. That is,
Minimum viscosity is 10⁶If it exceeds Pa · s, the precision glass tube
The pulling speed cannot be higher than a certain value,
Molding speed is very slow. In the present invention, in the heating furnace
The minimum viscosity of the base material glass tube is 10 ³-10⁶Pa · s range
It is important to be surrounded.

Further, the method for forming a precision glass tube of the present invention is characterized in that a difference in pressure between the inside and outside is provided in the base glass tube heated by using the pressure difference generating means.

A glass tube being stretch-molded is provided by providing a pressure difference between the inner and outer sides of a base material glass tube in a heating furnace having a minimum viscosity in the range of 10 ³ to 10 ⁶ Pa · s by using a pressure difference generating means. It is possible to inflate and deflate, and it is possible to mainly adjust the inner dimensions of the precision glass tube.

Further, the method for molding a precision glass tube of the present invention is characterized in that the pressure difference between the inside and outside of the base glass tube is measured by a differential pressure gauge,
The internal / external pressure difference is controlled to a predetermined value by inputting a signal of the internal / external pressure difference to a differential pressure adjuster and operating a differential pressure generating means.

By measuring the pressure difference between the inside and outside of the base glass tube using a differential pressure gauge, inputting a signal of the difference between the inside and outside pressures to the controller, and operating the differential pressure generating means to perform feedback control of the inside and outside pressure difference, The minimum viscosity is 10 ³ ~ using the differential pressure generating means.
It becomes possible to stabilize the internal / external pressure difference provided in the base material glass tube in the heating furnace in the range of 10 ⁶ Pa · s.

The method for forming a precision glass tube of the present invention measures the inner size of the precision glass tube at the time of stretch forming using a laser measuring device and inputs a signal of the inner size to the inner size adjuster. It is characterized in that the pressure difference between the inside and the outside of the base material glass tube is controlled by operating the differential pressure generating means.

The inner dimension of the precision glass tube is stabilized within a desired range by measuring the inner dimension of the precision glass tube at the time of stretch forming using a laser measuring device and feedback-controlling the pressure difference between the inner and outer sides of the base material glass tube. It becomes possible.

Further, in the method for forming a precision glass tube of the present invention, the outer size of the precision glass tube at the time of stretch forming is measured by using a laser measuring device, and a signal of the outer size is input to the outer size adjuster. It is characterized in that the pulling speed of the precision glass tube is controlled by operating the pulling means.

By measuring the outer dimension of the precision glass tube at the time of stretch forming using a laser measuring instrument and feedback controlling the pulling rate, it is possible to accurately stabilize the outer dimension of the precision glass tube within a desired range. Becomes

The method of forming a precision glass tube according to the present invention measures the inner and outer dimensions of the precision glass tube at the time of stretch forming using a laser measuring device to determine the difference between the inner and outer pressures of the base glass tube and the precision glass. It is characterized by simultaneously controlling the pulling speed of the pipe.

By measuring the inner and outer dimensions of the precision glass tube at the time of stretch forming by using a laser measuring device and feedback-controlling the pressure difference between the inner and outer sides of the base glass tube and the pulling speed of the precision glass tube, the precision glass tube is controlled. It is possible to simultaneously stabilize the inner and outer dimensions that affect each other.

At this time, it is preferable to construct an outer diameter control system that operates independently of the inner diameter control system so that the outer diameter and the inner diameter can be adjusted independently of each other.

Further, the differential pressure generating means, the tensioning means, and the feeding means may be operated fully automatically by interlocking the signals of the respective regulators.

[0021]

The method of forming a precision glass tube according to the present invention has a structure having a very high degree of freedom with respect to the above-mentioned forming dimensions of the precision glass tube and a highly stable molding condition. It is possible to stably manufacture many kinds of precision glass tubes having different inner / outer dimension ratios from one kind of base glass tube made of crystallized glass.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION First, a molding apparatus used in the method for molding a precision glass tube of the present invention will be described.

As shown in FIG. 1, the forming apparatus is connected to the feeding means 2 having a hermetically-sealed structure and a gripping portion 2a for gripping the base material glass tube 1 as a basic structural portion, and the gripping portion 2a. The differential pressure generating means 3 including the pump 3b connected to the pipe 3a and driven by the motor 3c, and the preform glass tube 1 are heated to a predetermined temperature at which the minimum viscosity is 10 ³ to 10 ⁶ Pa · s. A precision glass tube 20 having a desired range of inner and outer dimensions having a different inner-outer dimension ratio from the base material glass tube is obtained by extending the lower part of the base material glass tube 1 with a heating furnace 4 and a pair of rollers 5a and 5b. And a pulling means 5 for molding.

To further explain, in the feeding means 2,
The base material glass tube 1 held by the holding portion 2a is, for example, 1
It is sent into the heating furnace 4 at a constant speed V1 of about 100 mm / min to 100 mm / min.

Next, as shown in FIGS. 1 and 3, the differential pressure generating means 3 is connected to a pipe 3a of a vent hole provided in the grip portion 2a having an airtight structure, and is connected to the pipe 3a. A differential pressure gauge 3d is provided in the middle of the pump 3b. The differential pressure (positive pressure or negative pressure) is converted into an electric signal and input to the differential pressure adjuster 3e.
By adjusting the rotation speed of the motor 3c that drives b, the pressure difference between the inside and outside of the base glass tube 1 can be freely adjusted. In this way, by changing the pressure difference between the inside and outside of the base material glass tube 1 during the stretch molding, mainly the inner hole 20 of the precision glass tube 20.
The inner diameter of a can be freely changed.

As shown in FIG. 2, the heating furnace 4 includes a heater 4a for heating the base material glass tube 1 to a predetermined temperature having a minimum viscosity of 10 ³ to 10 ⁶ Pa · s, and a furnace temperature. The thermocouple 4b for measuring the temperature and the electric signal of the thermocouple 4b are input to the temperature controller 4c, and the power controller 4d that outputs when the temperature is lower than the target temperature is operated to operate the base glass tube 1 Is stabilized at a predetermined temperature at which the minimum viscosity of 10 ³ to 10 ⁶ Pa · s is obtained.

As shown in FIG. 4, the pulling means 5 is composed of a pair of rollers 5a and 5b and is rotationally driven by a driving means (not shown). It is necessary to rotate the rollers 5a and 5b at a constant rotation speed. Therefore, a rotary encoder 5f is installed on the rollers 5a and 5b, and a signal from the rotary encoder 5f is input to the rotation adjuster 5e to keep the rotation speed of the motor 5g for driving the rollers 5a and 5b constant.

With each of the above control loops operating individually, the inner and outer dimensions of the glass tube were measured by the laser measuring device 6 for inner and outer dimensions during stretch forming, and the electrical signals of the measured values were measured. Is input to the inner and outer size adjusters 6a and 6b.

The inner size adjuster 6a gives a command to the change in inner size to the differential pressure adjuster 3e of the differential pressure control loop described above.
The control loop after the differential pressure adjuster 3e is as described above.
In this way, the inner size can be stabilized at the target value.

The command from the external size adjuster 6b is input to the rotation adjuster 5e described above. The control loop after the rotation adjuster 5e is as described above. In this way, the outer dimension can be set to the target value.

As described above, the control loops for the inner and outer dimensions are separate, and a control system that operates independently is constructed. Therefore, the inner-outer dimension ratio is different from the base glass tube having one inner-outer dimension ratio. A wide variety of precision glass tubes can be made.

Next, an example of a method for molding a precision glass tube according to the present invention will be described using the above molding apparatus.

For example, a base material glass tube 1 made of borosilicate glass having a minimum viscosity of 10 ⁴ Pa · s and a temperature of about 1000 ° C. and having an outer diameter of 100 mm, an inner diameter of 10 mm and a length of about 1 m is prepared. If a precision glass tube having an outer diameter of 2 mm is stretch-molded as it is, using this base glass tube 1, the reduction ratio is 0.02 times, so the value of the inner diameter is 0.2 mm, and the diameter is However, it is not possible to obtain a precision glass tube that accurately holds an optical fiber of 0.125 mm.

From the above base material glass tube 1, the diameter is 0.12.
Inner diameter 0.126mm + 0.0005 / -0mm, outer diameter 2mm for holding and fixing 5mm optical fiber accurately
A case of manufacturing the precision glass tube 20 of ± 0.005 mm will be described.

First, the base material glass tube 1 is held by the holding portion 2a of the feeding means 2, and the heating furnace 4 is held at a constant speed of 10 mm / min.
Send in. At this time, the feed rate of the base glass tube 1 is measured at the time of stretch forming, and a signal of the feed rate is input to a controller (not shown) to operate the feed means to increase the feed rate of the base glass tube 1. It is possible to control with a constant accuracy.

Next, in the heating furnace 4, the base glass tube 1 is heated to about 1000 ° C. at which its minimum viscosity is 10 ⁴ Pa · s. Specifically, the electric signals of the heater 4a and the thermocouple 4b for measuring the temperature in the furnace are input to the temperature controller 4c,
By operating the power controller 4d that outputs when the temperature is low with respect to the target of about 1000 ° C., the base glass tube 1
The temperature inside the heating furnace 4 is stabilized so that the minimum viscosity of the is exactly 10 ⁴ Pa · s. When the temperature inside the heating furnace 4 is higher than the target of about 1000 ° C., the temperature inside the heating furnace 4 can be easily lowered by reducing the output of the heater 4a. Also, from that in the present invention for adjusting the temperature distribution in the heating furnace 4, than to optimally manage the temperature history received when reaching is molded from preform glass tube 1 in a precision glass tube 20, 10 ³ Pa · It is possible to stably perform stretch molding even with a very low viscosity such as s.

Next, the precision glass tube 20 extending below the base glass tube 1 in the heating furnace 4 and having a substantially predetermined size and being substantially solidified is sandwiched between the pair of rollers 5a and 5b, and a sufficient frictional force is exerted. Is exerted, and the film is stretched by pulling at a pulling speed of 24.8 m / min. As a result, a precision glass tube 20 having an inner / outer dimension ratio different from that of the base material glass tube 1 is formed.

At this time, the inner and outer diameters of the precision glass tube 20 being stretch-molded by the inner and outer laser measuring devices 6 are set to 0.0001.
The measurement is performed with an accuracy of mm, and the electric signal of the measured value is input to each of the inner size adjuster 6a and the outer size adjuster 6b.

The inner size adjuster 6a gives a command for the change of the inner diameter to the differential pressure adjuster 3e of the differential pressure control loop described above.
The differential pressure adjuster 3e adjusts the internal / external pressure difference of the preform glass tube 1 by adjusting the rotational speed of the motor 3c that drives the pump 3b in accordance with the instruction from the internal size adjuster 6a. In this way, the inner diameter of the precision glass tube 20 can be stabilized within the target range of 0.126 mm + 0.0005 / -0 mm. The actual differential pressure is -15 mm.
Although it was H ₂ O, the differential pressure is not always constant because it depends on the temperature distribution of the heating furnace 4 and the molding speed.

On the other hand, the outer size adjuster 6b is a precision glass tube 20.
In order to maintain the outer diameter of the roller at the target value, the rotation controller 5e is instructed to change the rotation speed of the rollers 5a and 5b so that the pulling speed of the precision glass tube 20 becomes a predetermined value. The rotation adjuster 5e is a motor 5 that drives the rollers 5a and 5b.
By adjusting the number of revolutions of g, the pulling speed of the precision glass tube 20 is set to a predetermined value. In this way, the outer diameter can be stabilized within the target range of 2.000 mm ± 0.005 mm.

As described above, according to the present invention, the base glass tube 1 made of glass or crystallized glass is heated and stretch-formed with a low viscosity, so that the precision glass tube 20 has an accuracy of 0.0001 mm in outer and inner diameters. It became possible to stably mold with.

In the above embodiment, the outer diameter is 2.0.
The differential pressure when the precision glass tube 20 having a diameter of 00 mm and an inner diameter of 0.126 mm was stretch-molded was −15 mmH ₂ O, but the inner diameter is 0.150 mm and 0.25 even when the outer diameter is 2.0 mm.
When manufacturing a 2mm precision glass tube, each is -1
0 mmH ₂ O and -5 mmH ₂ O, and by adjusting the differential pressure, the precision glass tube 20 of interest regardless of the reduction ratio.
Can be molded. When the inner diameter of the precision glass tube is larger than the target value, it is possible to obtain the precision glass tube 20 having the target inner diameter by reducing the pressure difference to a negative pressure, that is, reducing the inside.

Further, in the embodiment of the invention described above, the pulling speed of the precision glass tube during stretch forming is measured by using a speedometer,
By inputting the signal of the pulling rate to the controller and operating the pulling means to control the pulling rate of the precision glass tube, it is possible to more accurately form a precision glass tube having inner and outer dimensions within a desired range.

Further, in the embodiment of the invention described above, the concentric cylindrical precision glass tube applied to the ferrule or the like of the single-core optical connector is shown, but the present invention is not limited to this, and one having a plurality of holes,
It can be applied to the molding of various precision glass tubes, such as those with irregularly shaped holes and those with irregularly shaped outer periphery.

[0045]

According to the present invention, various kinds of precision glass tubes having high dimensional accuracy can be obtained from a base glass tube made of glass or crystallized glass having one kind of inside / outside dimension ratio. It is possible to produce various kinds of precision glass tubes in a short period of time and at low cost, and it has an excellent effect in practical use.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a molding apparatus used in the method for molding a precision glass tube of the present invention.

FIG. 2 is an explanatory diagram of a heating furnace used in the present invention.

FIG. 3 is an explanatory diagram of an internal size control system used in the present invention.

FIG. 4 is an explanatory view of an external size control system used in the present invention.

[Explanation of symbols]

1 base material glass tube 2 sending means 2a gripping part 3 Differential pressure generating means 3d differential pressure gauge 3e Differential pressure regulator 4 heating furnace 4c Temperature controller 4d power controller 5 Pulling means 5e Rotation controller 5g motor 6 Laser measuring instrument 6a Internal size adjuster 6b External size controller 20 Precision glass tube

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masanobu Minami             2-7-1, Harashira, Otsu City, Shiga Prefecture             Air Glass Co., Ltd. F term (reference) 4G015 BA01 BB01 BB02 BB05

Claims (6)

[Claims] 1. A preform glass tube by grasping a preform glass tube made of glass or crystallized glass having an inside-outside dimension ratio within a predetermined range in a grasping portion of a feeding means and feeding the preform glass tube into a heating furnace. Has a minimum viscosity of 10 ³ to 10 ⁶ Pa
Molding a precision glass tube having a desired range of inner and outer dimensions different from that of the base material glass tube by heating to a predetermined temperature of s and stretching the lower part of the base material glass tube with a tension means. A method for forming a precision glass tube, characterized by: 2. A pressure difference between the inside and outside of the glass preform heated by using the pressure difference generating means.
The method for forming a precision glass tube according to. 3. The internal / external pressure difference is measured by measuring the internal / external pressure difference of the base material glass tube with a differential pressure gauge, inputting a signal of the internal / external pressure difference to a differential pressure adjuster, and operating the differential pressure generating means. The method for molding a precision glass tube according to claim 2, wherein the method is controlled to a value of. 4. A base material is obtained by measuring the inner size of a precision glass tube at the time of stretch forming using a laser measuring device, inputting a signal of the inner size to an inner size adjuster and operating a differential pressure generating means. 2. The pressure difference between the inside and the outside of the glass tube is controlled.
4. The method for forming a precision glass tube according to any one of 3 to 3. 5. A laser measuring device is used to measure the outer dimension of a precision glass tube during stretch forming, and a signal of the outer dimension is input to the outer dimension adjusting device to operate the pulling means to measure the precision glass tube. The method for forming a precision glass tube according to claim 1, wherein the pulling speed is controlled. 6. A laser measuring device is used to measure the inner and outer dimensions of a precision glass tube during stretch forming, and to simultaneously control the pressure difference between the inner and outer sides of the base glass tube and the pulling rate of the precision glass tube. The method for molding a precision glass tube according to any one of claims 1 to 5.