JPS5852939B2 - coating dies - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in coating dies used in the manufacture of optical fibers.

During spinning of optical fibers, a plastic coating is applied to the outer periphery of the spun optical fibers.

Conventionally, the coating die used for this coating had a structure as shown in FIG.

That is, the coating die 1 is vertically divided into two parts and has a funnel-shaped liquid reservoir 2 and a die hole 3 connected thereto.

The optical fiber 4 is then inserted into the die 1 from above the liquid reservoir 2 and pulled out through the die hole 3.

The coating agent 5 is supplied from above the liquid reservoir 2,
There was a drawback that the liquid level within the liquid reservoir 2 fluctuated due to its supply.

Furthermore, since the volume of the liquid reservoir 2 is small, it is necessary to frequently supply the coating agent.

Furthermore, as the optical fiber runs, the coating agent 5 in the liquid reservoir 2 is drawn into the optical fiber 4 and moves downward, as shown by the arrow 6 in FIG. 1B, and along the peripheral wall of the liquid reservoir 2. This method also has the disadvantage that since it generates a kind of vortex flow including upward movement, the heat of the optical fiber is transmitted to the entire coating material, and the curing of the coating material is delayed.

The present invention has been made based on the above-mentioned circumstances, and provides a coating die that has little variation in the liquid level due to replenishment of a coating agent and is free from the risk of curing.

The invention will now be described in detail with reference to the drawings.

In FIG. 2, the coating die 7 of the present invention has an outer cylinder 8 and an inner cylinder 9 that are vertically divided into two and are concentrically arranged, and a bottom plate 10 that connects the two.

The inner cylinder 9 has a funnel-shaped liquid reservoir 10 and a dyne hole 12 communicating with the lower end thereof and penetrating the bottom plate 10.

Furthermore, the inner cylinder 9 is provided with a plurality of through holes 13 distributed in the circumferential direction, which are parallel to the bottom plate 10 and connect the outer peripheral surface of the inner cylinder 9 to the peripheral surface of the liquid reservoir 11 .

In the coating die of the present invention having the above configuration, the coating agent 14 is supplied to the annular space between the outer cylinder 8 and the inner cylinder 9.

In the above configuration, the coating agent supplied to the space enters into the liquid reservoir 11 through the through hole 13.

As the optical fiber 15 travels, it adheres to its surface and exits the liquid reservoir, and the reduced amount of coating agent is replenished from the space through the through hole 13.

Therefore, the coating agent in the liquid reservoir 11 flows through the through hole 13 as indicated by the arrow 16, in a downward direction drawn by the optical fiber 15 as indicated by the arrow 17, and on the peripheral wall of the liquid reservoir 11 as indicated by the arrow 18. This results in a movement consisting of an upward flow along the .

Since the coating agent has a considerable viscosity, the amount passing through the through hole 13 is commensurate with the reduction in the amount of the coating agent in the liquid reservoir, and the liquid level in the liquid reservoir 11 becomes approximately constant.

Further, since the coating agent constantly flows into the liquid reservoir 11, the temperature increase due to the heat of the optical fiber is minimal, and curing is not stopped.

Furthermore, since the annular space between the inner cylinder and the outer cylinder in which the coating agent is held has a large volume, there is no need to frequently replenish the coating agent.

The present invention is not limited to the above embodiments.

For example, as shown in Figure 3+4, the lower end of the liquid reservoir 11 is connected to the bottom plate 1.
The thickness may be within 0, and the lower edge of the through hole 13 may be aligned with the upper surface of the bottom plate 10.

In this case, in order to ensure the axial length of the die hole 12,
A conical protrusion 19 may be formed on the bottom surface of the bottom plate.

[Brief explanation of the drawing]

Figures 1A and B are perspective views and sectional views of conventional coating dies, Figures 2A and B are perspective views and sectional views of one embodiment of the present invention, and Figure 3 is a sectional view of another embodiment of the present invention. It is a diagram.

Claims (1)

[Claims] 1 It has a two-part structure with an inner cylinder and an outer cylinder concentrically arranged and a bottom plate connecting one end of the inner cylinder and the inner cylinder has a funnel-shaped liquid reservoir whose diameter decreases toward the bottom plate, and a funnel-shaped liquid reservoir that communicates with the lower end and penetrates the bottom plate. A coating die characterized in that a die hole is provided, and a through hole is further provided that connects the outer circumferential surface of the inner cylinder and the circumferential surface of the liquid reservoir.