JP2519692Y2 - heating furnace - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear body heating furnace. More specifically, a heating furnace that heats a linear body using a heating fluid that flows in a cocurrent or countercurrent direction with the linear body, for example, a plastic monofilament, a plastic multifilament, a plastic hollow fiber, a plastic optical fiber, The present invention relates to a heating furnace for drawing and heat-treating linear bodies such as glass fibers, glass optical fibers, and carbon fibers.

[0002]

2. Description of the Related Art Usually, in such a heating furnace, heating gas, air, steam, or other inert gas flowing in a cocurrent or countercurrent direction with the moving direction of the linear object to be heated. The heating fluid of is used as a heat medium to heat the linear body,
Some treatment such as baking, drying, stretching, heat setting, etc. is performed.

Conventionally, in this kind of heating furnace, the furnace inlet,
By installing a special non-contact sealing mechanism at the outlet opening and suppressing the inflow of outside air into the furnace or the outflow of the heating fluid that is the heat medium from the furnace as much as possible, the temperature distribution and flow velocity distribution in the furnace can be improved. As an example of uniformization, there is a heating furnace disclosed in Japanese Patent Laid-Open No. 62-238986 previously proposed by the present inventors.

However, the above-mentioned conventional apparatus has a heating furnace inlet,
Even if the outflow of the heating fluid such as heating gas to the outside of the furnace or the inflow of outside air into the furnace is suppressed by strengthening the non-contact sealing of the heating fluid at the outlet, the temperature distribution in the width direction at the heating fluid inlet, or The temperature distribution in the width direction of the furnace caused by the non-uniform velocity distribution or the non-uniform velocity distribution could not be suppressed. Further, the fluctuation of the flow velocity in the furnace caused by the fluid vibration generated by the collision of the heated fluid blown from above and below the furnace cannot be suppressed by the seal strengthening, and there is still room for improvement.

[0005]

DISCLOSURE OF THE INVENTION The present invention has the above-mentioned problems, namely, temperature unevenness and flow speed unevenness in the width direction of the fluid in the heating fluid blowing portion into the heating furnace, or temperature unevenness and flow unevenness over time, and Is to eliminate the disturbance of the flow velocity in the furnace due to the vibration of the fluid caused by the collision of the vertically injected fluid. Furthermore, by eliminating these spots, irregularities, etc., it is possible to obtain a linear body with a uniform thickness by reducing the variation of the wire diameter in the longitudinal direction of the linear body and the difference between the linear bodies of the diameter variation. It is intended to provide a heating furnace that can be used.

[0006]

[Means for Solving the Problems] The present invention is as follows. In a heating furnace that heats a linear body that passes continuously using a heating fluid, at least one surface of the inner wall of the heating furnace is provided with a protrusion having a continuous length over the arrangement width of the linear body. Heating furnace. 2. The heating furnace according to claim 1, wherein the height (H) of the protrusion is 0.5 times or more the distance (L) from the tip of the protrusion to the passage of the linear body. 3. The number of protrusions is 1 to 1 per 1 meter of furnace length
The heating furnace according to the above 1 or 2, wherein the number is 0. By doing so, the purpose is achieved.

A detailed description will be given below with reference to the drawings. FIG. 1 is a sectional view of a heating furnace according to an embodiment of the present invention. Figure 2
FIG. 2 is a sectional view taken along the line AA of FIG. FIG. 3 is a configuration diagram when the heating furnace of the present invention is used in an optical fiber manufacturing line having a core-sheath structure.

In the figure, 1 is a heating furnace. Heating furnace 1
Has an opening inlet 2 and an opening outlet 3 at both ends in the longitudinal direction. The linear body 4 enters the heating furnace 1 through the opening inlet 2, is heated, and is taken out of the furnace through the opening outlet 3. Reference numeral 5 is a supply roller, and 6 is a take-off roller for feeding the linear body 4 into and out of the heating furnace 1, and if necessary, the take-up roller 6
The linear body 4 is stretched by increasing the peripheral speed of the above than the peripheral speed of the supply roller 5. Reference numeral 7 is a heat retaining heater provided on the inner wall of the heating furnace 1 to prevent the temperature of the heating fluid from decreasing.

8 is a heating fluid inlet, 9 is a heating fluid outlet,
In the present embodiment, the heating fluid flows countercurrent to the linear body 4. That is, the heating fluid inlet 8 and the heating fluid outlet 9
Is provided at a position close to the opening inlet 2 and the opening outlet 3 of the heating furnace 1, and is connected to a fluid heating device (not shown). The fluid flows from the fluid heating device to the heating fluid inlet, the heating furnace, and the heating fluid outlet. After that, it is circulated and used again to return to the fluid heating device. 10 is a seal which is an opening inlet 2 and an opening outlet 3
Is provided at the open end of the heating element and not in contact with the linear body, and suppresses the release of heat in the heating furnace.

Reference numeral 11 denotes a protrusion continuously provided in the heating furnace in a state of not contacting a linear object which is an object to be heated passing therethrough, in a range covering the arrangement width of the linear object. is there. The protrusions 11 are provided on the upper side or the lower side of the linear body or on both sides thereof. The shape of the protrusion is not limited. That is, the simplest form is to set the length within a range that covers the arrangement width of the linear body passing through the flat plate. The protrusion needs to have a length that covers the arrangement width of the linear body, and needs to be continuous during this period.

The distance (L) from the tip of the projection to the passage of the linear body is preferably as short as possible within the range where the linear body does not contact the tip of the projection, but generally, the material of the linear body and 0.5 to 30 m, depending on the shape and the intended treatment
m. Furthermore, the relationship between the distance (L) from the tip of the protrusion to the passage of the linear body and the distance from the wall surface of the heating furnace to the tip of the protrusion, that is, the height (H) of the protrusion is 0. It is preferable that the projection height is 5 times or more, but the moving speed is also a matter in addition to the shape and material of the linear body itself.

In FIG. 2, the heating furnace is separated into upper and lower parts, and the upper part opens the inside of the furnace by broken lines. This is very convenient when setting the filament in the heating furnace. That is, it is easy to start the operation in a state where the linear bodies in the heating furnace are uniformly arranged at the start of the operation and there is no slack or disorder between the linear objects.

FIG. 3 shows an example in which the heating furnace of the present invention is used in a production line of a core-sheath fiber such as an optical fiber. 1
2 is a mouthpiece, and the polymer sent from the gear pumps 13 and 14 is discharged as a core-sheath fiber 18. The gear pump 13 is supplied with the sheath component polymer 15, and the gear pump 14 is supplied with the core component polymer 16. Cooling air 17 is applied to the discharged core-sheath fiber 18 to cool it, and is taken up by a take-up roll 19. Subsequently, the core / sheath fiber 18 is stretched to a predetermined ratio between the take-up roll 19 and the draw roll 20, further drawn by the heat treatment roll 21, and finally wound up on the bobbin 22.

During the course of these steps, when the core-sheath fiber is stretched between the take-up roll 19 and the stretching roll 20, the heating furnace 1 is heated to heat the fiber being stretched for smooth stretching. I'm using it. The heating furnace 1 is also used when heat treatment is performed while keeping the peripheral speeds of the drawing roll 20 and the heat treatment roll 21 constant to make the fiber stable. In any case, the heating furnace of the present invention is optimal for eliminating the temperature unevenness and flow speed unevenness of the heating fluid in the width direction of the furnace, and ensures the yarn processing in each step.

[0015]

EXAMPLE A case where the heating furnace according to the present invention is used for stretching a plastic optical fiber will be described. As shown in FIGS. 1 and 2, the heating furnace used is one in which projections are provided on the upper and lower surfaces of the inner wall of the heating furnace in a direction substantially perpendicular to the yarn traveling direction and wider than the width in which the yarn is arranged. The effective length of the furnace was 2.5 m, and the number of protrusions was 3 at the upper surface and 6 at the lower surface, and were arranged at substantially equal intervals. The height in the furnace was 30 mm, the height of the protrusions was 5 mm, and the protrusions had a width of 8 mm and had a rectangular cross section, and were installed almost continuously with respect to the entire width of 430 mm in the furnace. As the yarn to be treated, a plastic optical fiber having a core-sheath structure was used. As a core component, a radical polymerization initiator and a chain transfer agent are added to commercially-purified commercially available methyl methacrylate to perform continuous bulk radical polymerization, and then monomers and the like are removed by a demonomer machine consisting of a uniaxial vent-type extruder. Then, polymethylmethacrylate having a weight average molecular weight of 83000 and a residual monomer ratio of 0.22% by weight was obtained and used. A commercially available fluorinated methacrylate was used as the sheath component.

The core component and the sheath component were continuously supplied and melt-composited at 250 ° C. to obtain an unstretched plastic optical fiber having a diameter of 1414 μm. Subsequently, this unstretched plastic optical fiber was stretched 2.0 times in a non-contact manner while being heated to 160 ° C. using the heating furnace of the hot air circulation system as described above,
Further, the dimensional stability was improved by carrying out a constant length heat treatment while heating at 165 ° C. in the same heating furnace, and it was wound by using a constant tension winder to obtain a stretched plastic optical fiber of 1000 μmφ.

The fluctuation of the wire diameter of the obtained plastic optical fiber was measured by using a laser diode type outer diameter measuring device manufactured by Keyence, and the fluctuation width of the thread diameter was 1000 μm.
It was as small as ± 1.6% to ± 2.1%, the shrinkage rate at 80 ° C. was as low as 0.51% to 0.57%, and was in a narrow range.

Comparative Example A plastic optical fiber was manufactured using the same raw materials, spinning conditions and equipment as in the above example except that no protrusions were provided on the upper and lower surfaces of the heating furnace inner wall.
m ± 2.0% to 2.7%, the shrinkage ratio at 80 ° C. was as high as 0.55% to 0.7%, and the variation was large. The above measurement results are summarized in Table 1.

[Table 1]

Since the heating furnace of the present invention is provided with the protrusions on the inner wall surface of the heating furnace, the unevenness of the temperature and the flow velocity of the heating fluid in the width direction of the furnace becomes small, and the linear diameter of the linear body to be processed and the linear body of the physical property are The gap can be reduced. Further, fluctuations in temperature and flow velocity in the vicinity of the inlet of the heating fluid are alleviated, so fluctuations in the wire diameter and physical properties in the longitudinal direction can be reduced. In addition, fluctuations in flow velocity due to vertical interference of the heating fluid are alleviated,
Variations in the wire diameter and the physical properties in the longitudinal direction can be reduced.

Further, since it is possible to separate the accompanying flow of the linear body, the heating efficiency is improved, and the heating temperature of the heating fluid can be lowered, so that the heating energy can be saved. In addition, since it is possible to make the temperature distribution in the furnace uniform, when tension is applied to the linear object, the fluctuation of the tension becomes small, the fluctuation of the linear object becomes small, and the fusion of the linear object occurs. Since it does not exist, cutting troubles due to fusion can be reduced.

[0021]

EFFECT OF THE INVENTION The present invention is extremely practical and excellent in that it can uniformly heat a linear object, which is an object to be treated, in the longitudinal direction as described above and evenly between the linear objects. It is possible to bring about the above-mentioned effects, and it is possible to mention the excellent industrial effect of achieving the purpose with an extremely simple structure and structure for obtaining such excellent practical effects.

[0022]

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a heating furnace according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an overall configuration diagram when the heating furnace of the present invention is used in a core-sheath fiber production line.

[0023]

[Explanation of symbols]

 1: Heating furnace 2: Opening inlet 3: Opening outlet 4: Linear body 5: Supply roller 6: Take-off roller 7: Heater heater 8: Heating fluid inlet 9: Heating fluid outlet 10: Seal 11: Protrusion 12: Base 13: Gear pump 14: Gear pump 15: Sheath component polymer 16: Core component polymer 17: Cooling air 18: Core-sheath fiber 19: Take-up roll 20: Stretching roll 21: Heat treatment roll 22: Bobbin

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G02B 6/00 366 G02B 6/00 366

Claims (3)

(57) [Scope of utility model registration request] 1. A heating furnace for heating a continuously passing linear body using a heatable fluid, wherein at least one inner wall surface of the heating furnace is provided with a projection having a continuous length over the arrangement width of the linear body. A heating furnace characterized by being provided. 2. The heating furnace according to claim 1, wherein the height (H) of the protrusion is 0.5 times or more the distance (L) from the tip of the protrusion to the passage of the linear body. 3. The number of protrusions is 1 per meter of length inside the furnace.
The heating furnace according to claim 1 or 2, wherein the number is 10 to 10.