JP2657725B2 - Glass fiber tensile test method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for tensile testing a glass fiber, and more particularly to a fiber in which both ends of a glass fiber test piece are attached to a testing device in a tensile test of a high-strength glass fiber (large diameter). By preventing breakage (so-called chuck breakage) at the mounting portion, the true breaking strength of the test piece can be measured, and the test accuracy can be improved.

[0002]

2. Description of the Related Art A tensile test using a metal material tester is performed by attaching both ends of a test piece to a chuck of the tester, mounting the test piece on the tester, and applying tension to the test piece. In a tensile test of a metal material, stress concentration occurs on the test piece at the holding part by the chuck, that is, the mounting part, and the test piece breaks at this point, so the shape of both ends of the test piece is devised so that stress concentration does not occur as much as possible. Have been. A tensile test of a glass fiber (hereinafter, referred to as a “fiber”) is basically performed in the same manner, but a glass fiber for optical communication is a very fine wire (for example, 1 micron).
25 μm) and the fiber has low toughness and is brittle. Therefore, if the mounting method of directly gripping both ends of the test piece with a chuck is adopted, the holding portion is easily broken by the chuck (so-called chuck breakage). The conventional mounting method cannot be used as it is. For this purpose, various measures have been taken to reinforce both ends of the fiber test piece, such as coating with an epoxy resin. There is also a device in which a mounting method for the chuck is devised. This prior art will be described with reference to FIG. In this mounting method, the outer periphery of a cylindrical chuck 1 is covered with a rubber layer 2, and both ends C of a fiber F (covered) are fixed around the rubber layer. Both ends 3 of the fiber F are disposed obliquely with respect to the axis 4 of the chuck 1, and both ends C of the fiber F are wound in a coil shape from above both ends 3 to form the two ends 3.
Hold down and fix. Both ends C of the fiber are strongly wound around the rubber coating layer 2 of the chuck 1 by the tension applied to the fiber, so that both ends 3 of the fiber do not slip off the chuck. However, this mounting method has an effect of preventing the breakage of the chuck because the breaking tension is small for the small diameter fiber, but the fiber diameter of the fiber becomes large, so that when the tension applied to the fiber increases, the chuck breaks. Become. Both ends of fiber 3
Is pressed down and bites into the surface of the rubber coating layer 2, so that the fiber diameter is small (for example, a glass fiber diameter of 125 μm).
m, coating diameter 250 μm), the step between both ends 3 of the fiber and the surface of the rubber coating layer is negligible,
Stress concentration occurring at both ends C of the coil-wound fiber due to this step does not matter so much. Therefore,
By this mounting method, the fiber diameter is small and the tension is 30
Tests up to Kg are possible. However, if the fiber diameter is large (for example, glass fiber diameter 500 μm, coating diameter 60)
0 μm), the tension reaches 150 kg to 200 kg, which causes the chuck to break. As the wire diameter increases, the step between both ends 3 and the surface of the rubber layer increases, and accordingly, a strong local force acts on portions of both ends C of the fiber that press down both ends 3, and The rubber layer is wrinkled by the tightening of both ends C of the fiber, and a large local force acts on both ends C due to the wrinkle. When the fiber diameter increases, the bending moment of both ends C wound in a coil shape acts. Is considered to be a cause of the chuck breakage.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has been devised by devising a structure of a chuck.
It is an object of the present invention to prevent the local large force from acting on both ends C by devising a fixing method of the both ends 3 of the fiber, thereby effectively and surely preventing the large-diameter fiber from breaking the chuck. Things.

[0004]

[Means taken to solve the problem] The means taken to solve the above problem are composed of the following elements (a) to (c). (A) A pair of chucks is constituted by a main mandrel having three annular flanges on both sides and a center and a sub-mandrel having two annular flanges on both sides, and the diameter of the mandrel is set to 300 times the fiber wire diameter of the fiber test piece. Wound both ends of the test piece in a coil shape (spiral) around the two annular grooves of the main mandrel of the glass fiber tensile tester, and apply the adhesive tape to the inner surface of the flange on both sides of the main mandrel. Fixed by
(B) wrapping the middle of the test piece having both ends fixed to the main mandrel around the annular groove of the sub-mandrel; and (c) stretching the fiber of the test piece between both mandrels and applying tension to the fiber. A glass fiber tensile test method for measuring the breaking strength by breaking by hanging.

[0005]

[Operation] The main mandrel has two annular grooves formed by flanges on both sides and a central flange.
The secondary mandrel has one annular groove formed by the annular flanges on both sides. The two ends of the fiber test piece are wound around the two annular grooves of the main mandrel in a coil shape (spiral shape), and the ends are fixed to the inner surfaces of the flanges on both sides of the main mandrel with an adhesive tape. The middle of the test piece whose both ends are fixed to the main mandrel is wound around the annular groove of the sub-mandrel. As a result, the test piece is stretched between the main mandrel and the sub-mandrel. As in the conventional case, the main chuck and the sub chuck are separated from each other by the load cell, and tension is applied to the test piece. When the wire diameter of the test piece is 500 μm for the glass fiber portion and the coating diameter is 600 μm, the diameter of the mandrel is 150 mm.
Since the circumferential length of the mandrel is 471 mm, both ends of the test piece are bent with a very large radius of curvature compared to the wire diameter, and both ends are wound around the main mandrel with a very long length. Will be attached. Therefore, the total frictional force between the mandrel and both ends of the test piece is very large even if the fixing force to both ends of the test piece is small. Thereby, both ends of the test piece are firmly fixed to the main mandrel. Further, since the radius of curvature of both ends wound in a coil shape is sufficiently large with respect to the wire diameter, the bending force applied to both ends of the test piece by the bending moment is sufficiently small. Furthermore, since the two ends are fixed to the inner surfaces of the flanges on both sides of the main mandrel by the adhesive tape, the both ends C are not wrapped around the two ends 3 so that the above-mentioned problem caused by this is eliminated. Not at all. 1/2 for vice mandrel
Since it is only wound around, there is no problem that the chuck is broken. As the wire diameter of the test piece increases, the magnification of the mandrel diameter with respect to the wire diameter of the test piece is preferably larger (for example, the wire diameter of the glass fiber portion 80 is larger).
When the coating diameter is 0 μm and the coating diameter is 1000 μm, the magnification is 500.
About twice). Further, “300 times” of the above component (a) does not necessarily have a so-called critical technical significance, but has a large wire diameter (for example, a glass fiber portion 5).
When the magnification is 300 times or less, the degree of achievement of the above-mentioned problem is not particularly remarkable. When the magnification is 300 times or more, the degree of achievement of the problem becomes more remarkable. This means that the above is necessary. In the above description of the operation, it has been described that both ends of the test piece is fixed to the inner surface of the flange of the main mandrel by an adhesive tape, but this does not necessarily mean that the fixing is limited to the adhesive tape. This means fixing by a simple and convenient fixing method (locking means) using a simple clip, a set screw, or the like, which means that this is sufficient. Therefore, fixing with a clip, a set screw or the like is also included in the “fixing with an adhesive tape” in this specification. Also,
The main mandrel was provided with at least one notch in each of the annular flanges on both sides thereof, and the tip of the test piece was pulled out of the flange through the notches in the flanges on both sides of the main mandrel and pulled out. It is also possible to adopt a configuration in which both ends are fixed to the outer surfaces of the flanges on both sides by an adhesive tape.

[0006]

Next, an embodiment of the present invention will be described with reference to FIGS. The main mandrel 11 attached to the load cell 10 has an annular flange 12 on both sides and a central annular flange 13, and has two annular grooves 14, 15 formed by these flanges. The sub-mandrel 21 has annular flanges 22 at both ends,
An annular groove 23 is formed by the two flanges. The fiber test piece F is wound in a coil shape so that one end of the fiber test piece F does not overlap the annular groove 14, and the tip end f is fixed to the inner surface of the flange 12 with an adhesive tape 17. After fixing one end, the fiber test piece F is wound around the annular groove 23 of the sub-mandrel 21 and the other end is returned to the main mandrel again.
Similarly, the other end is wound around the annular groove 15 of the main mandrel 11, and the end is fixed to the inner surface of the flange 12 with an adhesive tape. Next, another embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. The main mandrel 11 in the above embodiment of the present invention is replaced with annular flanges 12 on both sides thereof.
Is provided with at least one notch 16 respectively, and the tip f of the fiber test piece is pulled out of the flange 12 through the notch 16 of the flanges 12 on both sides of the main mandrel, and both ends are drawn out. It is fixed to the outer surfaces of the flanges 12 on both sides by an adhesive tape 17. It is desirable to increase the circumferential length L of the notch 16 to minimize the bending of the fiber at the notch 16 as much as possible. The other configuration of this embodiment is the same as the configuration of the above embodiment. In this embodiment, since the main mandrel has the above-described structure, the tip f of the fiber test piece f
Can be more easily, easily and reliably attached to the main mandrel. The fiber wire diameter is 80
0 μm, coating diameter 1000 μm, diameter of main and sub mandrels is 640 mm, width B of main mandrel is 29 mm, width b of annular grooves 14 and 15 is 10 mm, diameter of annular flange 12 is 660 mm, thickness t of annular flange is 3 mm It is.
The number of windings n around the main mandrel at both ends of the fiber test piece is four. According to the above embodiment, the number of test pieces is 50.
FIG. 5 shows the results of a tensile test performed on the sample, and the breaking load was constant at 400 kg. Note that the horizontal axis in FIG. 5 indicates the measured breaking strength, and the vertical axis indicates the cumulative breaking probability. The above test results prove that the present invention does not cause any chuck breakage and measures the breaking strength of a true fiber due to tensile breaking.

[0007]

The object of the present invention is novel, and by solving this new problem, even in a tensile test on a fiber having a wire diameter of several hundreds of μm, it is possible to reliably prevent the chuck from being broken, and to achieve a stable and high performance. The greatest unique effect of the present invention is that the accuracy of the test results can be reliably obtained. Further, the present invention can sufficiently cope with an increase in the fiber diameter by increasing the chuck diameter by increasing the magnification with respect to the fiber diameter. Has the great advantage that it can be performed. Furthermore, even though the test apparatus applies a large tensile force to the test piece, the mechanism for mounting the test piece using the chuck does not use a special tightening mechanism, so the mechanism structure is extremely simple. The removal operation is extremely simple and easy.

[Brief description of the drawings]

FIG. 1 is a plan view of an embodiment of the present invention.

FIG. 2 is a side view of the embodiment of FIG.

FIG. 3 is a plan view of a main mandrel according to another embodiment of the present invention.

FIG. 4 is a side view of the main mandrel of the embodiment of FIG.

FIG. 5 is a table showing the results of a tensile test according to an example of the present invention.

FIG. 6 is a front view of the prior art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cylindrical chuck 2 ... Rubber layer 3, f ... Fiber tip 4 ... Axis 10 ... Load cell 11 ... Main mandrel 12, 22 ... Both side annular flange 13 ... Central annular flanges 14, 15, 23 ... Circular grooves 16 ... Notches 17 ... Adhesive tape 21 ... Submandrel F ... Fiber C ... Fiber both ends B ...・ Width of main mandrel b ・ ・ ・ Width of annular groove t ・ ・ ・ Thickness of annular flange L ・ ・ ・ Length of notch 16 in circumferential direction

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A 60-37848 (JP, U) JP-A 62-86537 (JP, U) JP-A 55-170650 (JP, U)

Claims (2)

(57) [Claims] 1. A pair of chucks is constituted by a main mandrel having three annular flanges on both sides and a center and a sub-mandrel having two annular flanges on both sides, and the diameter of the mandrel is set to the fiber diameter of the fiber specimen. Of 30
In a glass fiber tensile tester, at least 0 times, both ends of a test piece are respectively wound in a coil shape (spiral shape) around two annular grooves of the main mandrel, and the front ends thereof are inside surfaces of flanges on both sides of the main mandrel. To the main mandrel, wrap the middle of the test piece around the annular groove of the sub-mandrel, wrap it between both mandrels, stretch the fiber of the test piece, and tension the fiber. Glass fiber tensile test method to break by applying 2. The main mandrel according to claim 1, wherein at least one notch is provided in each of the annular flanges on both sides of the main mandrel, and the tip of the fiber test piece is passed through the notches in the flanges on both sides of the main mandrel. Pull out of the flange,
2. The glass fiber tensile test method according to claim 1, wherein the drawn out ends are fixed to the outer surfaces of the flanges on both sides by an adhesive tape.