JPH095538A - 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, a supporting member 20 for horizontally supporting the device body 10 and the polymerizing pipe P 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 peripheral and longitudinal directions of the polymerizing pipe P are built in the device body 10. These electrical heaters adjacent to each other in the peripheral direction of the device body 10 are so arranged as to deviation in positions in the longitudinal direction of the device body 10. A control means 30 has plural control mechanisms to respective discretely 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. 7 (a), the apparatus main body 51 has a structure like an electric blanket having a built-in one electric heater 52 for covering the entire heating region of the polymerization tube P 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 polymerization tube P reaches the set temperature by the one electric heater 52 which is responsible for the entire heating region over substantially the entire length of the polymerization 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 be generated 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 provided with a control means for controlling the heating of the polymerization tube by the apparatus body, in the apparatus body, in a heating region divided in the circumferential direction and the longitudinal direction of the polymerization tube. There is provided a plurality of heating means that respectively bear the heating areas that are adjacent to each other in the circumferential direction and are displaced in the longitudinal direction, and the control means individually controls each of the heating means. The control mechanism to do so was provided.

Further, it is desirable that a heat insulating member for partitioning the inside and outside of the heating region of the polymerization tube be provided between the apparatus main body and the polymerization tube at both ends of the apparatus main body.

[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 circumferential direction and the longitudinal direction of the polymerization tube are individually heated in correspondence with each heating region. The temperature can be freely controlled by the means and the control mechanism.

Further, the heating means adjacent to each other in the circumferential direction are
Since they are displaced in the longitudinal direction, the gaps between the heating means arranged in the longitudinal direction are heated to some extent by the heating means adjacent in the circumferential direction.

Further, in the case where the heat insulating members are provided at both ends of the apparatus body, the heat inside the apparatus body does not escape to the outside.

[0012]

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 having a built-in electric heater as a heating means as described in the prior art, but is divided in the circumferential direction and the longitudinal direction of the polymerization tube P. 2 is different from the conventional one in that individual electric heaters are built in the areas surrounded by the one-dot chain line in FIG. 2 so as to respectively handle a plurality of heating areas.

As shown in FIGS. 2 and 3, the electrothermal heater 11 built in the apparatus main body 10 includes an electrothermal heater group 11a which is in charge of the upper half of the polymerization tube P and a lower half of the polymerization tube P. It constitutes a group of electric heaters 11b that bears the electric heaters 11a and 11b arranged in the longitudinal direction of the polymerization tube P.

Further, the electrothermal heaters 11 constituting the electrothermal heater groups 11a and 11b are arranged such that the electrothermal heater groups 11a and 11b are displaced from each other in the longitudinal direction of the polymerization tube P. Therefore, the gap between the electric heaters 11 of the one electric heater group 11a, 11b can be complemented by the electric heater 11 of the other electric heater group 11b, 11a. It should be noted that, of the electrothermal heaters 11 constituting the electrothermal heater groups 11a and 11b, one electrothermal heater 1 arranged on different end sides.
1 is larger than the other electrothermal heaters 11 in order to absorb the above-mentioned deviation.

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 22, three support rods 23 are laid around the supported polymerization P, and 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 a power supply line 12 of each electric heater 11 built in the apparatus body 10, and has a plurality of control mechanisms (not shown) for individually controlling each electric heater 11. ) Is provided. Also,
Each control mechanism feedback-controls each electrothermal heater 11 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. Is able to.

In the heating device 1 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 P are provided with individual electric heaters corresponding to the respective heating regions. 11 and the control mechanism, the temperature distribution of the polymerization tube P during heating can be controlled, for example, in a flat state as shown in i) of FIG. 4 or polymerization as shown in ii) of FIG. The central portion of the pipe P is high, and the temperature may linearly decrease as the distance from the central portion increases.

Therefore, in the 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 generation of bubbles and polymerization distortion due to polymerization shrinkage can be prevented. be able to.

Moreover, as described above, the apparatus body 1
Since the electrothermal heaters 11 constituting the electrothermal heater groups 11a and 11b built in 0 are displaced in the longitudinal direction of the polymerization tube P, a gap portion between the electrothermal heaters 11 of one electrothermal heater group 11a and 11b To the other electric heater group 11
By supplementing each of the electric heaters 11b and 11a, the entire polymerization tube P can be uniformly heated.

In this embodiment, the heating region of the polymerization tube P is divided into two parts in the circumferential direction such as the upper half part and the lower half part, but it is divided into three, four and so on. It is also possible to provide an electric heater corresponding thereto. However, even in that case, it is necessary to arrange the electric heaters in each electric heater group so that the electric heaters adjacent to each other in the circumferential direction are displaced in the longitudinal direction of the polymerization tube P.

Further, as shown in FIG.
When the heat insulating member 13 for partitioning the inside and outside of the heating region of the polymerization tube P is provided between both ends of 0 and the polymerization tube P, the apparatus main body 10
Since the heat inside does not escape to the outside, there is little heating loss and controllability is improved.

[0024]

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 circumferential direction and the longitudinal direction of the polymerization tube are provided in a plurality of corresponding heating regions. Since the temperature is controlled individually by the heating means and the control mechanism, it is possible to control the polymerization rate in each part of the polymerization tube and prevent the generation of bubbles and the polymerization distortion due to the polymerization shrinkage.

Moreover, since the heating means adjacent to each other in the circumferential direction are displaced from each other in the longitudinal direction, the gap portion between the heating means arranged in the longitudinal direction is heated to some extent by the heating means adjacent to each other in the circumferential direction, and a plurality of heating means are provided. Even if the polymerization tube is heated by the heating means, the entire polymerization tube can be heated uniformly.

Further, in the case where the heat insulating members are provided at both ends of the apparatus body, the heat inside the apparatus body does not escape to the outside, so that there is an effect that the heating loss is small and the controllability is improved.

[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 perspective view showing an arrangement of electric heaters in the above apparatus body.

FIG. 4 is a graph showing a temperature distribution of the polymerization tube when the polymerization tube is heated using the heating device for producing a preform.

FIG. 5 is a perspective view showing an apparatus main body according to another embodiment.

FIG. 6 is a perspective view showing a conventional example.

FIG. 7 is a diagram showing the details of the above apparatus body.

FIG. 8 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 Electric heaters 11a, 11b Electric heater group 12 Power supply line 13 Heat insulating 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 is a heating region divided in a circumferential direction and a longitudinal direction of the polymerization tube, and the heating regions adjacent to each other in the circumferential direction are the longitudinal regions. A plastic optical fiber, comprising: a plurality of heating means respectively responsible for respective heating regions that are deviated in a direction, wherein the control means has a control mechanism for individually controlling each of the heating means. Heating device for preform production. 2. The plastic optical fiber preform fabrication according to claim 1, wherein heat insulating members for partitioning the inside and outside of the heating region of the polymerization tube are provided between the apparatus main body and the polymerization tube at both ends of the apparatus main body. Heating device.