JPH05215656A - Method for testing tensile strength of fiber connecting section - Google Patents

Abstract

PURPOSE:To provide a method for testing tensile strength of fiber connecting sections which can accurately test the tensile strength of a fiber connecting section and, at the same time, can inspect the fracture of a multiple fiber one by one after conducting tensile strength tests. CONSTITUTION:Fibers 3 and 4 connected to each other in such a way that end faces 1 and 2 of the fibers 3 and 4 are butted to each other and the contact section between the fibers 3 and 4 is fused are respectively pulled in the opposite directions with motors 5 and the tensile strength of the connecting section 6 of the fibers 3 and 4 is tested based on the values of the electric currents flowing to the motors 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for testing the tensile strength of a spliced portion of two fibers which are made by abutting the end faces of two optical fibers against each other and by fusion splicing.

[0002]

2. Description of the Related Art It has been a conventional practice to test the tensile strength of the connecting portion after the end faces of two optical fibers are butted and connected to each other. In this case, conventionally, as shown in FIG. 3, two fibers C and D whose end faces A and B are fusion-spliced are separately held by holders E and F, and the holders E and F are springs G, The tensile strength of connection I was tested by pulling in opposite directions with H.

[0003]

When the ends of the fibers are cut to form the connection end faces of the fibers to be connected, the cut length may deviate by several mm and the fiber length may vary. If this variation occurs, the tensile force of the spring becomes weaker or stronger depending on the length of the fiber, and an accurate tensile strength test cannot be performed. Although it is possible to test the tensile strength with the conventional tensile strength test method, it is possible to detect fracture when the fracture of the multicore fiber is detected after the tensile strength test and when all the cores of the multicore fiber are fractured by the tensile strength test. However (when the light is cut off), when only some of the fibers are broken, it is difficult to detect the breakage of the individual fibers because the light is not completely cut off. When pulling with a spring, the position of the fusion splicing part shifts before and after pulling, so if the fusion splicing part is photographed with a fixed monitor camera to detect breakage, the fusion splicing part is It becomes out of sight and break detection becomes impossible. In order to confirm the breakage of each fiber, it is necessary to visually inspect each fiber one by one after conducting a tensile strength test, which is very troublesome and difficult to detect with certainty. Therefore, at present, breakage detection may not be performed in the case of a multi-core fiber. In the case of fusion splicing of optical fibers, the heated and melted optical fibers are pressed against each other and then temporarily pulled back (fusion fusion tension), but in the conventional fusion machine for multicore fibers,
It was difficult to separately set the tensile force for fusion and the tensile force for screening (tensile test).

An object of the present invention is to provide a tensile strength test method for a fiber splicing portion which can perform an accurate tensile strength test and can inspect breakage of a multicore fiber for each core after the tensile strength test.

[0005]

As shown in FIG. 1, a method for testing the tensile strength of a fiber splicing portion of the present invention uses a motor 5 for fibers 3 and 4 in which end faces 1 and 2 are abutted and fused together.
The tensile strength of the fiber connecting portion 6 is tested based on the current value flowing in the motor 5 at that time.

[0006]

According to the tensile strength test method of the fiber connecting portion of the present invention, the fusion spliced fibers 3 and 4 are pulled by the motor 5 in opposite directions to each other, and the fibers are connected based on the current value flowing in the motor 5. Since the tensile strength of the portion 6 is tested, there is no error due to the deviation of the cut length of the fiber, and an accurate tensile strength test can be performed. Further, since the fiber connecting portion 6 is not displaced during the tensile test, it is possible to photograph the connecting portion 6 with a fixed monitor camera and automatically detect the breakage of the multicore fiber for each core.

[0007]

EXAMPLES The tensile strength test method of the fiber connecting portion of the present invention will be described in detail based on the example shown in FIG.

In FIG. 1, reference numerals 3 and 4 denote fibers, which are fixed to holders 11 and 12, and feed screws 13 and 14 are attached to the jigs 11 and 12, respectively. A transmission gear 15 attached to
16 meshes with drive gears 20 and 21 attached to rotary shafts 18 and 19 of the motor 5.

Then, the pulse / voltage conversion circuit (P
/ V conversion circuit) 22 is input for a certain period of time with a minimum number of palace PIs commensurate with the accuracy range of the tensile load. In response to the input, a voltage of VO∝ (PI-PF) is output from the P / V conversion circuit 22 (PI: input pulse, PF: feedback pulse), and its output causes two motors (DC motor).
5) rotate in reverse to each other by the input pulse (PI).

The rotation of the motor 5 causes the drive gear 20,
21 and the transmission gears 15 and 16 rotate, and the holders 11 and 1
2 is pulled in opposite directions, and the fibers 3, 4 held by the holders 11, 12 are also pulled in opposite directions.

When the motor 5 rotates by the input pulse (PI), the amount of rotation is detected by the encoder 23,
The feedback pulse PF for the input pulse (PI) is P
Returning to the / V conversion circuit 22, the motor 5 stops.

After that, if the input of the pulse (PI) and the feedback are repeated at a constant time interval, the fibers 3 and 4 are gradually pulled and the slack disappears, and the feedback pulse PF does not return to the P / V conversion circuit 22 ( PF becomes 0). Therefore, if the pulse PI is input at a constant time interval thereafter, the output voltage VO of the P / V conversion circuit 22 increases due to the relationship of VO∝ (PI-PF), and finally a current commensurate with the tensile force is obtained. It flows to the DC motor 5.

Output voltage V from the P / V conversion circuit 22
Although O is added to the current detection circuit 24 as well, the current detection circuit 2
Reference numeral 4 indicates that the voltage VS is not output from the comparator 25 unless a voltage higher than the reference voltage Vcc is applied.
Moreover, the reference voltage Vcc is set to the tensile test passing value. As a result, at the beginning of the tensile test, the voltage VS is not output even if the output voltage VO is applied to the current detection circuit 24 from the P / V conversion circuit 22, and then the pulse P is output at a constant time interval.
I is input to the P / V conversion circuit 22, the output voltage VO from the P / V conversion circuit 22 increases, and the voltage VS is not increased until the current corresponding to the tensile force is applied to the motor 5. It is output and judged to have passed the tensile test.

In the tensile test, when the connected fibers 3 and 4 are broken, the feedback pulse PF always returns to the P / V conversion circuit 22 (P
(F does not become 0), the output voltage VO from the P / V conversion circuit 22 does not increase forever, does not reach the reference voltage Vcc, and the tensile test is judged to have failed.

Since a large amount of current flows when the motor 17 shown in FIG. 1 is started, if the output TS of the current detection circuit 24 shown in FIG. 1 is detected at the same time when the input of the input pulse PI is started, the current at the motor start is detected. Since the pass / fail of the tensile test cannot be accurately determined, the output TS is detected after a certain time has elapsed after the input of the input pulse PI, and the rising current of the motor is cut off.

Simultaneously with the tensile test, the connection part 6 of the previously connected fibers 3 and 4 is photographed by a TV camera as shown in FIG. 2, and image processing is performed to monitor the same. It is possible to automatically detect whether or not is broken. Moreover, in this case, the breakage of the multi-core fiber can be detected for each core.

The motor 5 may be dedicated to a tensile test, but a motor used for pushing the fibers 3 and 4 when the end faces 1 and 2 of the fibers 3 and 4 are butted against each other and fused together. A motor for setting the end face of the fiber or a motor used for pushing in when the fibers 3 and 4 are fusion-spliced can also be used after being rotated in the opposite direction from the original use.

[0018]

According to the tensile strength test method of the present invention, the tensile strength test of the fiber can be accurately performed, and further, the fracture of the multi-core fiber can be automatically inspected for each core after the tensile strength test. .

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of a tensile strength test method of the present invention.

FIG. 2 is an explanatory view when a tensile strength test method of the present invention is used together with a fracture inspection method for a multicore fiber.

FIG. 3 is an explanatory diagram of a conventional tensile strength test method.

[Explanation of symbols]

 1 and 2 are end faces 3 and 4 are fibers 5 are motors 6 are fiber connecting parts

Claims (1)

[Claims] 1. Fibers 3 and 4 in which end faces 1 and 2 are butted against each other and are fusion-spliced are pulled in opposite directions by a motor 5, and a fiber connecting portion 6 is pulled based on a current value flowing in a motor 5 at that time. A method for testing tensile strength of a fiber connecting portion, which comprises testing strength.