JPH04233434A - Optical fiber proof test - Google Patents

Abstract

PURPOSE:To enable tensile application test without accompanying a collapsing of a cover layer even with respect to an optical fiber strand with a fine diameter by specifying a tightening pressure of a belt lap pulley on incoming and outgoing sides. CONSTITUTION:Tightening pressure by a belt 6 of a belt lap pulley 5 on turn pulleys 4 and 9 on the incoming and outgoing sides is kept within a range of 0.2-1.5kg/cm<2> to run an optical fiber strand 2. When the tightening pressure is under 0.2kg/cm<2>, the belt 6 deflects too much and comes off to cause a trouble such as slipping. When the pressure exceeds 1.5kg/cm<2>, a side pressure becomes excessive to incur a collapse of a cover layer of a strand 2. The tightening pressure causes manual rotation of the pulley 5, and a film-like pressure sensor sandwiched between the pulley 5 and the belt 6 measures a pressure when positioned at the lowest point of the pulley 5 as tightening pressure to be adjusted by a tension or the like of the belt 6.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a proof test method for testing the mechanical strength of optical fibers, particularly thin optical fiber strands.

0002

2. Description of the Related Art FIG. 1 shows a testing apparatus used in a conventional proof testing method of this type, and reference numeral 1 in the figure indicates a delivery drum. An optical fiber strand 2 to be examined is wound around this delivery drum 1, and the optical fiber strand 2 is fed out at a constant speed. The optical fiber strand 2 sent out from the sending drum 1 first passes through a sending-side dancer roll 3 and then is sent to an incoming-side turn pulley 4.

The input turn pulley 4 includes a belt wrap pulley 5, a belt 6 that contacts a part of the circumferential surface of the belt wrap pulley 5 and runs while holding down the optical fiber 2, and a belt 6 that drives the belt 6 to run. Three drive pulleys 7
It consists of... The optical fiber 2 guided to the input turn pulley 4 is inserted between the belt wrap pulley 5 and the belt 6, and then sent to the tension pulley 8.

The tension pulley 8 is constantly biased in the feeding direction of the optical fiber 2 by a spring or the like, and the optical fiber 2 passes through the tension pulley 8, reverses its running direction, and moves in the winding direction. When running, tension is applied to the optical fiber 2 in its longitudinal direction.

The optical fiber 2 from the tension pulley 8 is
It is sent to the outgoing turn pulley 9, from there it is sent to the winding drum 11 via the winding dancer roll 10, and is wound up. The outgoing turn pulley 9 has the same configuration as the incoming turn pulley 4 described above. Further, the pulley group such as the tension pulley 8 is made of metal such as aluminum or stainless steel.

According to the test method using this proof test device, a constant force is applied to the optical fiber 2 running at a speed of about 200 m/min between the incoming turn pulley 4 and the outgoing turn pulley 9 by the tension pulley 8. If there is a part where the mechanical strength is reduced due to scratches, cracks, etc. on the bare optical fiber or the coating layer that makes up the optical fiber strand 2, the It breaks, making it possible to detect defective parts and conducting proof tests.

By the way, in such a proof test, due to its mechanism, tension is applied to the optical fiber strand 2 and, at the same time, a considerably large lateral pressure is applied to the portion that contacts both turn pulleys 4 and 9.

[0008] Current bare wire diameter is 125 μm, strand diameter is 250 μm.
In the optical fiber strand of m, the coating layer has a strength that is almost permissible against this lateral pressure.

However, when the wire diameter is 150 to 200μ
In the case of a thin optical fiber having a diameter of m, the thickness of the coating layer becomes thin, and the coating layer cannot withstand the above-mentioned lateral pressure and is crushed, so that the bare optical fiber becomes partially exposed. and,
If this bare optical fiber portion comes into contact with a pulley or the like of the testing device, it will easily break.

[0010] For this reason, it is not possible to measure the mechanical strength of the optical fiber itself, and the optical fiber often breaks due to crushing of the coating layer, making accurate proof testing difficult. If this process is not carried out, there are disadvantages such as a decrease in yield.

[0011]

[Problems to be Solved by the Invention] Therefore, the problem to be solved by the present invention is to provide a proof testing method that allows tension application tests to be performed on small-diameter optical fibers without crushing the coating layer. It's about getting.

In order to solve this problem, the present invention adopts a method in which the tightening pressure of the belt trap pulleys on the incoming and outgoing sides of the testing apparatus is set to 0.2 to 1.5 kg/cm2.

The present invention will be explained in detail below.

In the proof test method of the present invention, the tightening pressure by the belt 6 of the belt wrap pulley 5 of the turn pulleys 4 and 9 on the incoming and outgoing sides is set to 0.2 to 1.5 kg.
This is done by running the optical fiber 2 and applying tension while maintaining the tension within the range of /cm2.

[0015] If the tightening pressure is less than 0.2 kg/cm2, the belt 6 will bend too much and may come off or slip. Also, 1.5kg/c
If it exceeds m2, the lateral pressure becomes excessive, leading to crushing of the coating layer of the optical fiber strand 2.

The tightening pressure is measured by inserting a membrane-like pressure sensor between the belt wrap pulley 5, its circumferential surface, and the belt 6.
This is done by manually rotating the belt wrap pulley 5 and using the pressure when the pressure sensor is located at the lowest point of the belt wrap pulley 5 as the tightening pressure. This pressure is adjusted by adjusting the tension of the belt 6 or the like. The belt 6 is preferably made of relatively soft polyurethane rubber or the like, and is particularly preferably made of a material having a Shore D hardness of 60 or less according to JIS-K-7215.

[0017] In such a proof test method,
Even at the curved portions of the optical fiber 2 at the incoming and outgoing turn pulleys 4 and 9, excessive lateral pressure is not applied to the coating layer. Therefore, even for a small-diameter fiber strand having a thin coating layer, the coating layer is not crushed by the lateral pressure, and breakage of the optical fiber strand due to crushing of the coating layer is prevented. Therefore, a proof test that accurately reflects the mechanical strength of the thin optical fiber strand will be performed.

[0018] A concrete explanation will be given below by showing examples.

(Example 1) Optical fiber bare wire diameter 125 μm
, 20km of optical fiber with a diameter of 180μm was manufactured, and the span length was 10m at the start and end of the fiber.
A tensile test was performed on each optical fiber, and it was confirmed that there were no low-strength portions over the entire length of the optical fiber.

[0020] Next, this optical fiber was cut into pieces of 5 km each, and repeated proof tests were conducted under the condition that the amount of strain was 1.0%. This test was conducted by repeating the proof test five times for each 5 km of optical fiber using the testing apparatus shown in FIG. 1, and recording the cumulative number of breaks per 5 km each time. This test was conducted while changing the tightening pressure, and the relationship between the tightening pressure and the cumulative number of breaks is shown in FIG.

In the graph of FIG. 2, curve A shows a case where the tightening pressure is 5 kg/cm2 on both the outgoing and incoming turn pulleys, and curve B shows a case where the deviation is also 3 kg/cm2.
kg/cm2, curve C is similarly 2k
g/cm2 and curve D are both 1.5
It is expressed in kg/cm2.

(Example 2) The tightening pressure and cumulative number of breaks were determined in the same manner as in Example 1 except that an optical fiber having a diameter of 200 μm was used and the amount of strain was 1.5%. The results are shown in Figure 3.
Indicated. In the graph of Figure 3, curve E shows the tightening pressure of 4k on both the outgoing and incoming turn pulleys.
g/cm2, curve F is similarly 3 kg.
/cm2, curve G is similarly 1.0k.
It is expressed in g/cm2.

It can be seen from the graphs in FIGS. 2 and 3 that by setting the tightening pressure to 1.5 kg/cm 2 or less, an accurate proof test that reflects the original strength of the optical fiber can be performed.

[0024]

As explained above, in the optical fiber proof testing method of the present invention, the tightening pressure of the incoming and outgoing turn pulleys is set to 0.2 to 1.5 kg/cm2, so that the coating layer Even with thin, small-diameter optical fiber strands, there is no crushing due to the lateral pressure of the coating layer, and accurate proof tests that accurately reflect the strength of the optical fiber can be performed.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a proof testing device used for optical fiber proof testing.

FIG. 2 is a graph showing results in Examples.

FIG. 3 is a graph showing results in Examples.

[Explanation of symbols]

2 Optical fiber wire 4　Incoming side turn pulley 5 Belt trap pulley 6 Belt 8 Tension pulley 9 Output side turn pulley

Claims (1)

[Claims] [Claim 1] Using a test device having a belt wrap pulley and a belt that runs the optical fiber while pressing it against the belt wrap pulley, an incoming and outgoing turn pulley, and a tension pulley, an optical fiber is strung between these pulley groups. In a proof test method in which the mechanical strength of an optical fiber is tested by applying a constant tension to the optical fiber while running the optical fiber, the tightening pressure by the belt on the surface of the belt wrap pulley on the incoming and outgoing turn pulleys is set to 0. An optical fiber proof testing method characterized in that the weight is 2 to 1.5 kg/cm2.