JPH095537A - Heater for forming preform of plastic optical fiber - Google Patents

Abstract

PURPOSE: To provide a heater for forming a preform of a plastic optical fiber capable of controlling the degree of polymn of a raw material monomer in the respective parts of a polymerizing pipe by arbitrarily setting the temp. distribution of the polymerizing pipe under heating. CONSTITUTION: This heater is composed of a cylindrical device body 10 for heating the cylindrical polymerizing pipe P housing the raw material monomer therein by enclosing the polymerizing pipe P over approximately the entire length in the longitudinal direction thereof, a supporting member 20 for horizontally supporting the device body 10 and the polymerizing pipe P in the state of enclosing the polymerizing pipe P with the device body 10 and a control means 30 for controlling the heating of the polymerizing pipe P by the device body 10. Plural electric heaters respectively bearing the plural heating regions divided in the longitudinal direction of the polymerizing pipe P are built in the device body 10. The control means 30 has plural control mechanisms to respectively control the respective electric heaters.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic optical fiber in which a raw material monomer is heated and polymerized in the polymerization tube by heating a cylindrical polymerization tube containing the raw material monomer in the step of producing a plastic optical fiber preform. The present invention relates to a heating device for producing a preform.

[0002]

2. Description of the Related Art As a heating device for producing a preform of this type, there is one shown in FIG. The heating device 50 for producing a preform comprises a device main body 51 that surrounds a cylindrical polymerization tube P containing a raw material monomer over substantially the entire length of the polymerization tube P and heats it, and a polymerization tube P formed by the device main body 51. And the control means 54 for controlling the heating.

As shown in FIG. 6 (a), the main body 51 of the apparatus has a structure like an electric blanket in which one electric heater 52 which covers the entire heating region of the polymerization tube P is built in as a heating means. As shown in FIG. 2B, the roll is rolled into a cylindrical shape by fixing both ends thereof with a fixing means such as a magic tape 53.

Further, the control means 54 controls the polymerization pipe P
The temperature at one point in the longitudinal direction is measured by a temperature sensor 55 such as a thermocouple, and the heating means 52 of the apparatus main body 51 is controlled so that this temperature becomes a predetermined temperature.

[0005]

However, in the above-mentioned heating device 50 for making a preform, the above-mentioned device body 51 is used.
However, the heating control is performed so that the temperature of a part of the polymerizing tube P reaches the set temperature by one electric heater 52 which is in charge of the entire heating region over substantially the entire length of the polymerizing tube P.
As shown in, the temperature distribution generated in the polymerization tube P has no regularity, and the polymerization rate of the raw material monomer varies depending on the site of the polymerization tube P. As a result, there are problems that bubbles are likely to occur in the preform due to polymerization shrinkage, and that polymerization distortion is large.

Therefore, an object of the present invention is to preform a plastic optical fiber capable of controlling the polymerization rate of the raw material monomer in each part of the polymerization tube by arbitrarily setting the temperature distribution of the polymerization tube during heating. It is to provide a heating device for manufacturing.

[0007]

In order to solve the above-mentioned problems, the present invention relates to an apparatus main body for heating a cylindrical polymerization tube containing a raw material monomer by enclosing and heating the polymerization tube over substantially the entire length thereof. In a heating device for producing a preform of a plastic optical fiber, which comprises a control means for controlling the heating of the polymerization tube by the apparatus body, in the apparatus body, a plurality of heating regions divided in the longitudinal direction of the polymerization tube are provided. A plurality of heating means for each of them is provided, and the control means is provided with a control mechanism for individually controlling each of the heating means.

Further, it is desirable to provide a heat insulating member for partitioning between the heating means adjacent to each other between the apparatus main body and the polymerization tube.

[0009]

In the heating device for producing a preform of a plastic optical fiber having the above-mentioned structure, a plurality of heating regions divided in the longitudinal direction of the polymerizing tube are provided with individual heating means and control corresponding to the respective heating regions. The temperature can be freely controlled by each mechanism.

Further, in the case where the heat insulating member for partitioning the adjacent heating means is provided, the influence from the adjacent heating means is less likely to occur, so that the controllability is good.

[0011]

EXAMPLES Examples will be described below with reference to the drawings. As shown in FIG. 1, a heating device 1 for producing a preform for a plastic optical fiber is a device for heating a polymerization tube P by enclosing a cylindrical polymerization tube P containing a raw material monomer over substantially the entire length in the longitudinal direction. With the main body 10 and the apparatus main body 10 surrounding the polymerization tube P, the apparatus main body 1
0 and the polymerizing tube P are supported horizontally, and a control means 30 for controlling the heating of the polymerizing tube P by the apparatus body 10.

The apparatus main body 10 has a cylindrical structure in which an electric heater as a heating means is built in like the one described in the prior art, but a plurality of the polymerization tubes P are divided in the longitudinal direction. A plurality of electric heaters (not shown) are sequentially arranged in the area surrounded by the alternate long and short dash line in FIG. 2 so as to respectively cover the heating areas.

The support member 20, as shown in FIG.
The support plates 22 are provided upright on both ends of the substrate 21, and the polymerization tubes P can be horizontally supported by inserting both ends of the polymerization tubes P into the holes 22a formed in the both support plates 22. There is.

In addition, between the two support plates 12, three support rods 23 are laid around the supported polymerization interval P. The three support rods 23 support the two support plates 22. The apparatus main body 10 can be supported in a state in which the outer circumference of the formed polymerization tube P is surrounded at a constant interval.

The control means 30 is connected to the power source line 11 of each electric heater built in the apparatus main body 10, and comprises a plurality of control mechanisms (not shown) for controlling the electric heaters. There is. In addition, each control mechanism,
It is possible to perform feedback control of each electrothermal heater so that the temperature of each heating region measured by the thermocouple 31 arranged corresponding to each heating region of the above-mentioned polymerization tube P becomes the respective set temperature. ing.

In the heating device 1 for producing a preform for a plastic optical fiber having the above-mentioned structure, a plurality of heating regions divided in the longitudinal direction of the polymerizing tube P are provided with individual electric heaters corresponding to the respective heating regions. Since the temperature can be controlled respectively by the control mechanism and the control mechanism, the temperature distribution of the polymerization tube P during heating can be, for example, a flat state as shown in i) of FIG. 3 or a polymerization tube as shown in ii) of FIG. It is possible to arbitrarily set a state in which the central portion of P is high and the temperature linearly decreases with increasing distance from the central portion.

Therefore, in this heating device 1 for producing a preform for a plastic optical fiber, the polymerization rate of the raw material monomer in each part of the polymerization tube P can be controlled freely to some extent, and the generation of bubbles and the polymerization distortion due to the polymerization shrinkage can be reduced. be able to.

FIG. 4 shows another embodiment. In the above embodiment, in order to set the temperature distribution in the longitudinal direction of the polymerizing tube P to an arbitrary degree to some extent, a plurality of electric heaters corresponding to each heating region of the polymerizing tube P are built in the apparatus main body.
Since each electric heater is affected by the adjacent electric heaters, it is difficult to perform fine temperature control by each electric heater, and it is difficult to set each heating region to a stable target temperature environment.

For this reason, as shown in FIG. 4, a heat insulating member 12 for partitioning the adjacent electrothermal heaters is provided between the polymerization tube P and the apparatus main body 10 to block the influence from the adjacent electrothermal heaters. By doing so, the controllability of each electric heater can be improved.

[0020]

As described above, according to the heating apparatus for producing a preform of a plastic optical fiber of the present invention, a plurality of heating regions divided in the longitudinal direction of the polymerization tube are provided with a plurality of heating means corresponding to the respective heating regions. Further, since the temperature is individually controlled by the control mechanism, the polymerization rate at each part of the polymerization tube can be controlled, and the generation of bubbles and the polymerization distortion due to the polymerization shrinkage can be reduced.

Further, in the case where the heat insulating member for partitioning the adjacent heating means is provided, it is less susceptible to the influence of the adjacent heating means, so that the controllability is good and each part of the polymerization tube is surely secured. It can be set to the desired temperature.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment according to the present invention.

FIG. 2 is a perspective view showing the apparatus main body of the above.

FIG. 3 is a graph showing the temperature distribution of the polymerization tube when the polymerization tube is heated using the above preform-manufacturing heating device.

FIG. 4 is a partially cutaway sectional view of an apparatus body showing another embodiment.

FIG. 5 is a perspective view showing a conventional example.

FIG. 6 is a diagram showing details of the apparatus body of the above.

FIG. 7 is a graph showing a temperature distribution of a polymerization tube when the polymerization tube is heated using a conventional heating device for producing a preform.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Heating device for preform production of plastic optical fiber 10 Device body 11 Power supply line 12 Thermal insulation member 20 Support member 21 Substrate 22 Support plate 30 Control means 31 Thermocouple

Claims (2)

[Claims] 1. A device main body for heating a cylindrical polymerization tube containing a raw material monomer by surrounding the polymerization tube over substantially the entire length of the polymerization tube, and a control means for controlling heating of the polymerization tube by the device main body. In a heating device for producing a preform of a plastic optical fiber, the device body has a plurality of heating means respectively responsible for a plurality of heating regions divided in the longitudinal direction of the polymerization tube, the control means, the heating means A heating device for producing a preform of a plastic optical fiber, which has a control mechanism for individually controlling each of the means. 2. The heating device for producing a preform for a plastic optical fiber according to claim 1, further comprising a heat insulating member provided between the main body of the device and the polymerizing tube for partitioning the adjacent heating means.