JPS6316988B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for coating a wire with a low viscosity liquid plastic material.

Conventionally, wire rods have generally been coated using an extruder. With this method, it is difficult to directly coat a fragile wire such as an optical fiber due to frequent breakage. This type of extruder also targets thermoplastic resins such as polyethylene, nylon, and vinyl chloride. Coating optical fibers directly with plastics of this type has a negative effect on the transmission properties due to their high Young's modulus. Therefore, silicone resins with low Young's modulus are mainly used to coat optical fibers. The optical fiber is coated with silicone resin using an open crucible-shaped coating device, so as the linear speed increases, slippage occurs between the fiber and the resin, and the speed is limited to about 100 m/min at most. Ta. Further, there were drawbacks such as a large unevenness in the thickness of the coating layer. In addition, in a closed-type coating device consisting of a core and a cap, the viscosity of the silicone resin is as low as 5000 cps, so there are disadvantages such as uneven thickness and easy damage.

In order to eliminate these drawbacks, the present invention provides fins or grooves in the flow path of the plastic material formed by the base and mandrel. The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a sectional view of one embodiment of the present invention,
1 is an optical fiber, 2 is a metal core, 3 is a resin supply section, 4
5 is a base, 5 is a groove, and 6 is an opening. To coat the optical fiber 1 using this device, first insert the optical fiber 1 into the opening 6.
Run it through the Subsequently, the pressurized liquid plastic material is allowed to flow into the coating apparatus from the resin supply port 3. At this time, a groove 5 is formed on the outer periphery of the mandrel.
In some cases, grooves are also provided in the cap, so that the plastic flows in a spiral. Therefore, the plastic forms a vortex at the opening of the cap, and the vortex automatically moves the optical fiber to the center of the opening, thereby forming a coating layer with no uneven thickness. Further, due to the self-aligning effect of the optical fiber due to the vortex, the uncoated optical fiber does not come into contact with the base opening. In addition, by adjusting the supply pressure of liquid plastic, high-speed coating is possible.
Moreover, the thickness of the coating layer can be controlled.

The inner diameter of the opening is 0.5mmφ, and the outer diameter of the optical fiber is
When the coating material was a silicone resin having a viscosity of 5000 cps, coating was possible at a linear speed of up to 650 m/min at a resin supply pressure of 32 Kg/cm ² and the outer diameter of the coating layer was 375±3 μm. In addition, the breaking strength of the coated optical fiber was measured in a tensile test of 100 fibers at a gauge length of 20 m, with a minimum of 324 Kg/mm ² and a maximum of 533 Kg/mm 2 , and an average of 533 Kg/mm ² .
It was 521Kg/ ^mm2 .

Figure 2 shows the grooves on the outer periphery of the mandrel, 2 is the mandrel, 5
is a groove.

In FIG. 3, fins 7 are provided on the outer periphery of the mandrel instead of grooves.

As explained above, in the plastic coating apparatus of the present invention, a vortex is generated in the flow of liquid plastic by the grooves or fins, and the wire rod is self-centered in the opening by the action of this vortex. Therefore, a coating layer without eccentricity can be obtained. It also has the advantage of being able to coat low-viscosity materials and increasing the linear speed.

In the embodiments shown in FIGS. 1 to 3 described above, grooves or fins are provided on the outer periphery of the mandrel, but it goes without saying that grooves or fins are also provided on the mandrel and the mandrel and the mandrel are provided with grooves or fins. Similarly, a coating layer without eccentricity can be obtained by pressurizing and flowing the coating material into the voids formed by
It becomes possible to coat low-viscosity materials, and it is also possible to increase the linear speed.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a diagram showing a grooved mandrel, and FIG. 3 is a diagram showing a finned mandrel. DESCRIPTION OF SYMBOLS 1... Optical fiber, 2... Core metal, 3... Resin supply port, 4... Cap, 5... Groove, 6... Opening, 7
...Fin.

Claims (1)

[Claims] 1. A device that applies liquid plastic to the wire by passing a wire through an opening penetrating the center of the mandrel and the cap, and applying pressure to the gap formed by the mandrel and the cap. A plastic coating device characterized in that a plurality of spiral grooves or fins are provided in a gap formed by a base.