JPH0238946A - Testing method for vibration fatigue of stranded wire - Google Patents

Abstract

PURPOSE:To accurately and easily detect the fatigue rupture of element wires constituting the stranded wire by fixing an extremely thin insulated conductor which is connected to a power source to the outer periphery of the stranded wire and detecting electrically the breaking of the extremely thin insulated conductor which is caused by the rupture of the stranded wire. CONSTITUTION:The wire 1 which is held by a metallic fixture 2 by applying a specific tensile force axially is vibrated by an exciter 3 as specified and a vibration fatigue test is conducted. Then the enamel coated conductor 4 is wound around the outer periphery of the wire nearby the holding part and connected to an applied vibration controller 5. Then the wire 1 is vibrated by the exciter 3 as specified and the applied vibration controller 5 detects electrically the breaking of the enamel coated conductor 4 which is fed with electricity according to the fatigue rupture of an element wire constituting the wire 1, thereby stopping the exciter 3. Consequently, the fatigue rupture of the element wire is accurately detected and the repetitive vibration frequency up to the fatigue rupture is accurately grasped.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a fatigue testing method for stranded wires that makes it possible to accurately detect fatigue fractures in strands constituting stranded wires. .

(Prior Art) A vibration fatigue test is one of various characteristic tests for bare stranded wires such as AC9R and OPCV.

In this vibration fatigue test, a stranded wire is held under a predetermined tension in the axial direction, and the stranded wire is vibrated with a constant stress or a constant strain using an electromagnetic vibrator, etc. A method that detects the point at which one of the strands of strands breaks due to fatigue, and determines the strength against vibration fatigue of the stranded wire based on the relationship with the repeated vibration frequency applied until the strand reaches fatigue rupture. It is.

The characteristics of stranded wire against vibration fatigue are
This is one of the very important characteristics in knowing how strong the material is against vibrations caused by snow and other factors.

By the way, in this vibration fatigue test, it is important to accurately detect when the wire breaks.

For example, in the case of a vibration fatigue test of only strands, a microvoltage is applied to the strands held in an electrically insulated manner, and vibration is automatically detected by electrically detecting when the strands break. It is possible to accurately determine the number of repetitions until failure.

However, such a method cannot be used in the case of an electric wire such as AC9R or opcw, which is made by twisting together a large number of strands. Therefore, attempts have been made to detect when any of the strands forming a stranded wire undergoes fatigue rupture using the method described below.

■ When the stranded wire is repeatedly vibrated, the wires rub against each other and powder falls, so the amount of powder is observed to detect breakage.

■ Detects the sound when a strand of stranded wire breaks and detects the break.

■During the test, XL@ photography should be available at all times, and the images should be taken several times at the appropriate time to detect breaks.

(Problems to be Solved by the Invention) However, none of the methods (1) to (4) described above are definitive methods, and it has not been possible to reliably and accurately detect the rupture time using any of the methods. For this reason,
Based on the test data of only the strands and past test data, we estimate the number of repetitions it will take to break depending on the applied stress, stop the vibration based on this assumption, and rely on the method of visually detecting the breakage. I had no choice.

However, this type of visual detection inevitably causes errors in the number of repeated vibrations until fatigue failure, and the vibration must be stopped several times for verification, which requires a lot of time and effort. There was a problem.

The present invention was made in order to address the problems of the prior art, and is a method for vibration fatigue of stranded wires that makes it possible to accurately and easily detect fatigue fractures in the strands that constitute the stranded wires. The purpose is to provide a test method.

[Structure of the Invention] (Means for Solving the Problems) That is, the present invention provides a method for applying a predetermined vibration to a stranded wire and determining the strength of the stranded wires until they reach fatigue fracture. In the vibration fatigue test method, a finely insulated conductive wire is fixed to the outer periphery of the stranded wire, and a predetermined vibration is applied to the stranded wire while the finely insulated conductive wire is energized, and the finely insulated conductive wire is The present invention is characterized in that cutting of the insulated conductive wire is electrically detected and application of vibration to the stranded wire is stopped.

(Function) When the strands constituting the strands undergo fatigue fracture due to vibrations applied to the strands, the broken strands jump slightly outward or move in the axial direction of the strands. Therefore, by fixing an energized finely insulated conductor wire around the outer periphery of the stranded wire and performing a test by applying vibration to the stranded wire in this state,
Due to the behavior of the strands when they undergo fatigue rupture, the finely insulated conductive wires fixed to the outer periphery of the stranded wires are also cut. And this m
By electrically detecting the breakage of the thin insulated conductive wire, fatigue fracture of the wire can be accurately detected. In addition, by stopping the application of vibration at the same time as the energization to the finely insulated conductive wire is stopped, it is possible to accurately grasp the repetition frequency until fatigue failure occurs.

(Example) Next, implementation of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an example of a test device to which the method of the present invention is applied, in which a stranded wire 1 is held with a predetermined tension applied in the axial direction by a fixture 2, and this stranded wire is A vibration fatigue test is performed by applying a predetermined vibration to 1 using a vibrator 3 such as an electromagnetic vibrator.

The stranded wire 1 has, for example, diameters of 0 and 1 near its holding part.
A heavily enamel-covered conducting wire 4 is wound and fixed, and this enamel-covered conducting wire 4 is connected to an applied vibration control mechanism 5.

As shown in FIGS. 2 and 3, this enamel-coated conductor wire 4 is wrapped in a single layer around the outer circumference of the stranded wire 1, and is adhesively fixed to each of the outermost layer strands 1a of the stranded wire 1. has been done.

The diameter of the enamel-coated conductor 4 used is the stranded wire 1.
Any material may be used as long as it is sufficiently thinner than the strands 1a constituting the strands and can be easily cut by fatigue fracture of the strands 1a.

Further, the applied vibration control mechanism 5 is constituted by an electric circuit as shown in FIG. 4, for example.

A low voltage direct current is applied to the enamel-coated conductor 4 via a relay 11 that can be energized by a bushing switch PS. In addition, a circuit breaker 12 is inserted in the input line to the vibrator 3, and the circuit breaker 12 is activated in accordance with the operation of the movable piece M1 of the relay 11. It is configured to operate, and to stop at the same time as the energization is stopped by cutting the enamel-coated conductor 4.

Next, a vibration fatigue testing method for stranded wire using the testing apparatus having the above configuration will be described.

First, the circuit of the relay 11 connected to the enamel-coated conductor 4 of the applied vibration control mechanism 5 is closed, and a voltage of, for example, about DC5V is applied to the enamel-coated conductor 4, while the vibrator 3 is operated. By operating the vibrator 3, the stranded wire 1
Vibration based on a predetermined stress or strain is applied to. As the number of vibrations increases, fatigue accumulates in the strands 1a constituting the strand 1, and when the accumulated fatigue value exceeds the fatigue limit strength of each strand ↓a, line 1a
leads to fatigue failure.

When any one of the strands 1a breaks, the strand 1a jumps to the outer circumference as shown in FIG.
As shown in the figure, the strands 1a are pulled in the axial direction by the tension applied to the strands 1. The enamel-covered conducting wire 4 is cut by the behavior of these strands 1a. and,
When the enamel-coated conductor 4 is cut, the applied vibration control mechanism 5
At the same time as the relay 11 is activated, the electromagnetic breaker 12 is activated, cutting off the input power to the vibrator 3 and stopping the application of vibration.

In this way, by adhering and fixing the enamel-coated conductor wire to each strand in the outermost layer of the stranded wire, the enamel-coated conductor wire is cut when the strand breaks, and the breakage of the enamel-coated conductor wire can be detected. This makes it possible to accurately detect the fatigue rupture timing of the wire.

Then, by applying a voltage to the enamel-coated conductor and controlling the operation of the vibrator in the open and closed states of the circuit that includes this enamel-coated conductor, the applied vibration is stopped almost at the same time as the wire breaks due to fatigue. This makes it possible to accurately grasp the repeated vibration frequency up to fatigue failure.

Furthermore, when a vibration fatigue test was actually conducted on wires based on the above configuration, vibrations were able to be stopped in all cases when one of the wires broke. Furthermore, the test time for one stranded wire was reduced to approximately 175 minutes compared to the conventional method of visually checking the fracture status.

[Effects of the Invention] As explained above, according to the stranded wire vibration fatigue testing method of the present invention, it is possible to accurately and easily detect the point at which one of the strands of wire ruptures due to fatigue. becomes. Therefore, the reliability of the vibration fatigue test can be greatly improved, making it possible to more accurately determine the strength against I-line vibration.In addition, the test time is shortened compared to the conventional method, making it more economical. Momukai' 2.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the configuration of a test device to which the method of one embodiment of the present invention is applied, FIGS. 2 and 3 are enlarged views of the main parts of FIG. 1, and FIG. FIG. 1 is a circuit diagram showing the configuration of the applied vibration control mechanism, and FIGS. 5 and 6 are diagrams showing a broken state of the strands constituting the stranded wire. l...... Stranded wire 1a... Element wire 3... Vibrator

Claims (1)

[Claims] (1) A vibration fatigue test method for stranded wires in which a predetermined vibration is applied to the stranded wires and the strength of the wires constituting the stranded wires is determined until fatigue rupture occurs. A predetermined vibration is applied to the stranded wire while the finely insulated conductive wire is energized, and the breakage of the finely insulated conductive wire that occurs due to fatigue rupture of the strands is electrically detected. A vibration fatigue test method for stranded wire characterized by stopping the application of vibration.