WO2013002271A1 - Method for selecting flex-resistant conductive material, and cable using same - Google Patents

Abstract

This method for selecting a flex-resistant conductive material and whereby, from an S-N curve indicating the relationship between stress amplitude and number of cycles to failure determined by performing a fatigue test of a conductive material, the conductive material withstands a dynamic driving test having least one million repetitions. In a range of the number of repetitions of stress until failure of 10⁶-10⁷ repetitions in the S-N curve of the conductive material, the selection criterion is a regression line linearly approximating the finite lifetime region of fatigue failure determined at a stress amplitude value of y MPa and a number of repetitions of stress of x repetitions being in the region indicating a lower limit value using the function formula: y = -21.5 Ln (x) + 455.

Description

Method for selecting flexible conductive material and cable using the same

The present invention uses an SN curve showing the relationship between the stress amplitude (dynamic load) applied to the conductive material and the number of stress cycles (number of times to failure) to select a conductive material having excellent flexibility. The present invention relates to a method of selecting a flexible conductive material and a cable using the same.

With the spread of industrial robots, high performance has also been required for cables used therein. Among the required characteristics for cables, bending resistance is particularly important, and in the case of wire manufacturers, development of the bending resistant cable has become a major technical issue. Until now, soft copper wire for electricity has been mainly used as a conductive material for cables, but there is a growing need for cables whose bending resistance greatly exceeds 1,000,000 times. Here, as a dynamic driving test method for evaluating the bending resistance of the bending resistant cable, for example, a left / right bending test method of ± 90 degrees is adopted.

On the other hand, it is known that metal materials fatigue even under a load in the elastic range when they are repeatedly subjected to a load and eventually break. For this reason, if a metal material is subjected to a constant cyclic stress, it is grasped how many times it can withstand, and in order not to break it a certain number of times, the range of the cyclic stress should be within Because of this, the SN curve is widely used.
Regarding the application of this SN curve, for example, Patent Document 1 discloses the fatigue life of a copper material for determining the number of repeated cycles until the copper material breaks when the copper material is subjected to repeated stress whose amplitude fluctuates. An estimation method has been proposed. Further, Patent Document 2 proposes a method of calculating and predicting the life of a shear pin by using the shear pin S-N curve corresponding to the shaft torsional torque of a gas turbine. Further, Non-Patent Document 1 proposes a method of evaluating the fatigue characteristics of a material using a thin piece.

Japanese Patent Application Laid-Open No. 11-64203 JP 2000-37095 A

When selecting a conductive material necessary to develop a cable excellent in bending resistance, the cable bending test has been performed until now. However, there is a problem that a test time exceeding several tens of days is required for a test with more than 1,000,000 bending resistances, and a test time more than several hundred days is required for a test with more than 10 million bending resistances. Frequent cable bending tests to select conductive materials have been substantially difficult.
Further, the techniques of Patent Documents 1 and 2 obtain an SN curve for a specific material, and perform life prediction (prediction of fracture timing and replacement timing) using the obtained SN curve, for example, If prediction is to be made in a range in which the number of repetitions exceeds 10 million, it is necessary to obtain an SN curve by testing up to a range in which the number of repetitions exceeds 10 million. For this reason, it takes a long time to obtain the SN curve, and it can not be said that it is an effective life prediction method.
Further, the technique of Non-Patent Document 1 is to evaluate the fatigue fracture characteristics of a material using a thin plate test, and has the advantage that the SN curve of the material constituting the thin plate can be obtained in a short time. However, the bending resistance of the cable can not be predicted directly from the obtained SN curve.

The present invention has been made in view of such circumstances, and it is possible to use the SN curve of the conductive material positively and to select the conductive material having excellent flexibility quickly and easily. An object of the present invention is to provide a method of selecting a conductive material and a cable using the same.

According to the first aspect of the present invention, there is provided a method of selecting a flexible conductive material according to the first aspect of the present invention, wherein the conductive material is 100 from the SN curve showing the relationship between the number of breaks and the stress amplitude obtained by conducting a fatigue test of the conductive material. A method of selecting a flexible conductive material that can withstand 10,000 or more dynamic drive tests, comprising:
In the range of the stress repetition number up to 10 ⁶ to 10 ⁷ breakages in the SN curve of the conductive material, the finite life region of fatigue failure obtained by setting the stress amplitude value to y MPa and the stress repetition number to x is a straight line The selection criterion is that the fitted regression line is within the range indicated by the lower limit value y = -21.5 Ln (x) +455.

According to the second aspect of the present invention, there is provided a method of selecting a flexible conductive material according to the above object, wherein the conductive material is 500 from the SN curve showing the relationship between the number of breaks and the stress amplitude obtained by conducting a fatigue test of the conductive material. A method of selecting a flexible conductive material that can withstand 10,000 or more dynamic drive tests, comprising:
In the range of the stress repetition number up to 10 ⁶ to 10 ⁷ breakages in the SN curve of the conductive material, the finite life region of fatigue failure obtained by setting the stress amplitude value to y MPa and the stress repetition number to x is a straight line The selection criterion is that the fitted regression line is within the range indicated by the lower limit value y = -21.5 Ln (x) +475.

According to the third aspect of the present invention, there is provided a method of selecting a flexible conductive material according to the above object, wherein the conductive material is 1000 from the SN curve showing the relationship between the number of breaks and the stress amplitude obtained by conducting a fatigue test of the conductive material. A method of selecting a flexible conductive material that can withstand 10,000 or more dynamic drive tests, comprising:
In the range of the stress repetition number up to 10 ⁶ to 10 ⁷ fractures in the SN curve of the conductive material, the finite life region of fatigue failure obtained by setting the stress amplitude value to y MPa and the stress repetition number to x is a straight line The selection criterion is that the fitted regression line is in the range indicated by the lower limit value y = −21.5 Ln (x) +505.

According to a fourth aspect of the present invention, there is provided a method of selecting a flexible conductive material according to the fourth aspect of the present invention, wherein the conductive material is 2500 from the SN curve showing the relationship between the number of breaks and the stress amplitude obtained by conducting a fatigue test of the conductive material. A method of selecting a flexible conductive material that can withstand 10,000 or more dynamic drive tests, comprising:
In the range of the stress repetition number up to 10 ⁶ to 10 ⁷ fractures in the SN curve of the conductive material, the finite life region of fatigue failure obtained by setting the stress amplitude value to y MPa and the stress repetition number to x is a straight line The selection criterion is that the fitted regression line is in the range indicated by the lower limit value y = −21.5 Ln (x) +560.

In the method of selecting a flexible conductive material according to the first to fourth inventions, the function equation corresponds to a cable in which the test body used for the dynamic drive test is made of a wire having a wire diameter of d μm. The value of the y-intercept value of the functional equation is (z−d) / 2 for the selection of the flexible conductive material that can withstand the dynamic drive test of a cable that is configured and configured by a wire with a wire diameter of z μm. Preferably, the functional equation is corrected by adding the calculated correction value.

The cable according to the fifth invention in accordance with the object uses the conductive material selected by the method of selecting a flexible conductive material according to the first to fourth inventions.

In the method of selecting a flexible conductive material according to the first to fourth inventions, the conductive material is selected based on the data of the SN curve measured in the past or the data of the newly created SN curve. The bending resistance can be estimated, and it becomes possible to select the conductive material having the bending resistance according to the application quickly and simply without actually performing the dynamic drive test.

In the method of selecting a flexible conductive material according to the first to fourth inventions, a functional equation is set corresponding to a cable in which a test body used for a dynamic drive test is constituted by a strand of wire diameter d μm. In the selection of a flexible conductive material that can withstand the dynamic drive test of a cable composed of a wire with a wire diameter of z μm, the value of y-intercept in the functional equation is calculated by (z−d) / 2. In the case where the function equation is corrected by adding the correction value to be corrected, it is possible to select the flexible conductive material which can withstand the dynamic drive test in consideration of the wire diameter of the strands constituting the cable.

In the cable according to the fifth aspect of the invention, the SN curve of the conductive material is used for the cable application without actually performing a dynamic drive test of the cable (for example, a cable bending test). It is possible to select flexible conductive materials quickly and easily, and to manufacture reliable cables quickly and at low cost.

It is a SN curve which presumes the cable bending test fracture frequency range used by the selection method of the bending-resistant conductive material concerning one example of the present invention. The cable bending test is an SN curve in consideration of a change in wire diameter used when estimating the number of breakages of 1,000,000 times or more. It is explanatory drawing of the SN curve which estimates the cable bending test fracture | rupture frequency range. It is a SN curve of the conductive material of Experimental example 1-3. It is a SN curve of the electrically-conductive material of Experimental example 4-6. It is a SN curve of the electrically-conductive material of Experimental example 7 and 8. FIG. It is a SN curve of the electrically-conductive material of Experimental example 9-12.

The present invention will now be described by way of example with reference to the accompanying drawings in order to provide an understanding of the present invention.
In the method of selecting a flexible conductive material according to the first embodiment of the present invention, as shown in FIG. 1, an SN curve showing the relationship between the number of breaks and the stress amplitude obtained by conducting a fatigue test of the conductive material From the above, it is a method of selecting a flexible conductive material that the conductive material withstands a dynamic drive test of 1,000,000 times or more, and the number of stress cycles to 10 ⁶ to 10 ⁷ breakages in the SN curve of the conductive material In the range of y, the stress amplitude value is yMPa, the regression line which linearly approximates the finite life region of fatigue failure determined with x number of stress cycles, but the lower limit is a functional equation y = −21.5Ln (x) +455 (1 )
The selection criteria is to be within the region indicated by.

When a wire is made of a flexible conductive material and a cable is made of this wire, for example, a cable bending test is adopted as a dynamic drive test (the same applies to the second to fourth embodiments). be able to. Here, in the cable bending test, a cable having a cross-sectional area of 0.2 mm ² manufactured using a wire with a wire diameter of 80 μm is used as a test body, and a bending radius of 15 mm is applied with a load of 100 g applied to the test body. The bending angle range is performed by repeatedly applying right and left bending of ± 90 degrees.

In addition, the SN curve (same for the second to fourth embodiments) is 30 mm in length, 3 mm in width, 0.3 mm in thickness, using the same flexible conductive material as the cable wire. The fatigue test (stress repeated load test) of a test piece produced by mirror finishing the surface after forming a circular hole of 0.5 mm in diameter in the width direction center position of 24 mm from one end of the member I asked. In the fatigue test, the holder is attached to the other end of the test piece so that the tip of the holder is 1 mm from the center of the circular hole, one end of the test piece is downward and the holder is the voice coil portion of the speaker for sound , And the frequency was adjusted so that the test piece was in the primary resonance state by vibrating the voice coil. Then, the maximum stress occurring at the holder root of the test piece was obtained from the equation of bending stress of the cantilever, and it was taken as the stress amplitude at the time of fatigue test.

In the method of selecting a flexible conductive material according to the second embodiment of the present invention, as shown in FIG. 1, an SN curve showing the relationship between the number of breaks and the stress amplitude obtained by conducting a fatigue test of the conductive material From the above, it is a method of selecting a flexible conductive material that the conductive material can withstand 5 million or more dynamic drive tests, and the number of stress cycles until 10 ⁶ to 10 ⁷ breakages in the SN curve of the conductive material In the range of y, the stress amplitude value is yMPa, the regression line obtained by linearly approximating the finite life region of fatigue failure determined with x number of stress cycles, but the lower limit is a functional equation y = −21.5Ln (x) +475 (2 )
The selection criteria is to be within the region indicated by.

In the method of selecting a flexible conductive material according to the third embodiment of the present invention, as shown in FIG. 1, an SN curve showing the relationship between the number of breaks and the stress amplitude obtained by conducting a fatigue test of the conductive material From the above, it is a method of selecting a flexible conductive material that the conductive material withstands 10 million dynamic drive tests or more, and the number of stress cycles until 10 ⁶ to 10 ⁷ breakages in the SN curve of the conductive material In the range of y, the stress amplitude value is yMPa, the regression line obtained by linearly approximating the finite life region of fatigue failure determined with x number of stress cycles, but the lower limit is a functional equation y = −21.5Ln (x) +505 (3 )
The selection criteria is to be within the region indicated by.

In the method of selecting a flexible conductive material according to the fourth embodiment of the present invention, as shown in FIG. 1, an SN curve showing the relationship between the number of breaks and the stress amplitude obtained by conducting a fatigue test of the conductive material From the above, it is a method of selecting a flexible conductive material that can withstand a dynamic drive test of 25 million times or more of the conductive material, and the number of stress cycles to 10 ⁶ to 10 ⁷ times of breakage in the SN curve of the conductive material In the range of y, the stress amplitude value is yMPa, the regression line obtained by linearly approximating the finite life region of fatigue failure determined with x number of stress cycles, but the lower limit is a functional equation y = −21.5Ln (x) +560 (4 )
The selection criteria is to be within the region indicated by.

And, in the method of selecting a bending resistant conductive material according to the first to fourth embodiments, the test formulas used in the cable bending test have functional diameters of 80 μm (an example of d μm) according to the functional formulas (1) to (4). For the selection of a flexible conductive material that withstands the cable bending test of cables composed of strands of wire diameter of z μm, which are set corresponding to cables composed of strands of wire, function formulas (1) to (5) Correct the functional equation by adding the correction value calculated by (z-80) / 2 to the value of y-intercept in 4). FIG. 2 shows the relationship between the stress amplitude and the number of breaks shown by the functional equation obtained by modifying the functional equation (1) when the wire diameter of the strand is 50 and 100 μm, and the stress shown by the functional equation (1) This is shown together with the relationship between the amplitude and the number of breaks.
Hereinafter, the functional expressions (1) to (4) will be described.

Generally, in the SN curve obtained from repeated stress fatigue tests, in the finite life region where the number of stress cycles is 10 ⁶ to 10 ⁷ times, the relationship between the stress amplitude (repeated stress) and the number of breaks (number of stress cycles up to break) (Fatigue failure behavior) can be expressed by linear approximation, that is, the relationship between the stress amplitude and the number of breaks can be expressed using a linear function.
Furthermore, when a material with high fatigue resistance is selected in the repeated stress fatigue test and a cable bending test is performed using a cable composed of the selected material wires, high bending resistance is exhibited (the number of breakages is large). Results are obtained and it is known that the cyclic stress fatigue test results and the cable bending test results are in a corresponding relationship.

Therefore, in a fatigue test of a test piece made of the conductive material P using the conductive material P as a reference material, a linear function (straight line) p indicating fatigue fracture behavior in a 10 ⁶ to 10 ⁷ finite life region is determined. If the number of fractures Np is obtained from the cable bending test of a cable composed of a strand formed of the conductive material P, the fatigue test using the conductive material Q of different materials shows that 10 ⁶ to 10 ⁷ times of finite When a linear function q indicating fatigue fracture behavior in the life region is determined, if a linear function q is present on the high stress side (high breaking frequency side) from the linear function p, it is composed of strands formed of the conductive material Q It is expected that the number of breaks Nq obtained from the cable bending test of the obtained cable is larger than the number of breaks Np. On the other hand, if the linear function q is on the low stress side (low breaking frequency side) from the linear function p, the breaking frequency Nq obtained from the cable bending test of the cable composed of the strands formed of the conductive material Q is broken. It is expected to be smaller than the number Np.

Therefore, a test piece is manufactured using copper with a purity of 99.9% as a reference material, and a fatigue test is performed to obtain a linear function (straight line) indicating fatigue fracture behavior in a 10 ⁶ to 10 ⁷ finite life region. The Moreover, the cable bending test of the cable comprised from the strand formed with 99.9% of purity copper was done, and the number of times of breakage was calculated | required. An SN curve showing a fatigue fracture behavior in a 10 ⁶ to 10 ⁷ finite life region of 99.9% pure copper is shown in FIG. The linear function (regression line) showing the fatigue failure behavior in the 10 ⁶ to 10 ⁷ finite life region is y = -21.5L n (x where y is the stress amplitude value and x is the stress repetition rate (times). The number of breakages obtained in the cable bending test was 10 million.

Then, when the fatigue fracture behavior can be expressed by a linear function, if the material is a test piece of the same material, the difference in the fatigue fracture behavior can be expressed as the linear function obtained by translating the obtained linear function Be done. For this reason, the linear function representing the fatigue failure behavior in the finite life region of 10 ⁶ to 10 ⁷ times in the material of the strands constituting the cable whose number of breakages obtained in the cable bending test is 1,000,000 times is a cable The linear function showing the fatigue fracture behavior in the 10 ⁶ to 10 ⁷ finite life region of the material whose number of breakages in the bending test is 10 million times is moved to the low number of breakages side so that the number of breakages becomes 1/10 Determined by Therefore, for example, y = -21.5Ln (x) + 455 as a linear function indicating the fatigue fracture behavior of the material of the strand corresponding to 1,000,000 times of cable breakage in the 10 ⁶ to 10 ⁷ finite life region. Do.

In addition, the linear function showing the fatigue fracture behavior in the finite life region of 10 ⁶ to 10 ⁷ times in the material of the strands constituting the cable having a number of breaks of 5,000,000 obtained in the cable bending test is the cable bending. The linear function showing the fatigue failure behavior in the 10 ⁶ to 10 ⁷ finite life region of the material whose number of breakages in the test is 10,000,000 is moved to the low number of breakages so that the number of breakages becomes 1/2. Determined by. Therefore, for example, y = −21.5Ln (x) +475 that represents a linear function indicating the fatigue fracture behavior in a 10 ⁶ to 10 ⁷ finite life region of a material of a strand corresponding to 5 million cable breaks. Do.

On the other hand, the linear function showing the fatigue fracture behavior in the finite life region of 10 ⁶ to 10 ⁷ times in the material of the strands constituting the cable whose number of breakages obtained in the cable bending test is 25 million is a cable bending The high fracture frequency side is estimated by a linear function showing the fatigue fracture behavior in a 10 ⁶ to 10 ⁷ finite life region of a material whose fracture frequency in the test is 10,000,000. For this reason, in order to prevent underestimation, the linear life function showing the fatigue failure behavior in the 10 ⁶ to 10 ⁷ finite life region of the material in which the number of breakages in the cable bending test is 10 million times is 10 times the fracture life. It is determined by moving it to the high breaking frequency side so that Therefore, for example, y = -21.5Ln (x) + 560, which represents a linear function indicating the fatigue fracture behavior of the material of the strand corresponding to 25 million times of cable breakage in the 10 ⁶ to 10 ⁷ finite life region. Do.

The distortion generated when the wire diameter of a strand is z μm is R with the bending radius R in the cable bending test is (R + z / 2) / R, and the distortion generated when the wire diameter of a strand is 80 μm is , (R + 80/2) / R. Therefore, when the wire diameter of the wire is 80 μm, the strain change that occurs when the wire diameter of the wire is z μm is {(R + z / 2) / R}-{(R + 80/2) / R} = (z-80) / (2R). For this reason, when the wire diameter of the wire is larger than 80 μm, the strain generated in the cable bending test becomes larger than that in the case where the wire diameter of the wire is 80 μm, and the generated stress also becomes larger. On the other hand, when the wire diameter of the wire is smaller than 80 μm, the strain generated in the cable bending test becomes smaller than in the case where the wire diameter of the wire is 80 μm, and the generated stress also becomes smaller.

Therefore, when reflecting the difference in the wire diameter of the strands in the cable bending test on the SN curve obtained in the repeated stress fatigue test, the linear function showing the fatigue failure behavior corresponds to the generated strain change It is necessary to move along the stress axis by the value of. The stress is determined as the product of the strain and the elastic modulus of the test piece used in the repeated stress fatigue test, so the wire diameter dependent portion (z-(z-) with respect to the wire diameter of 80 μm. Incorporating only the 80) / 2 into the linear function in an independent form, the linear function representing the fatigue failure behavior when the difference in the wire diameter at the cable bending test is reflected in the SN curve is y = -21.5 Ln (x) + K + (z-80) / 2. Here, K is a y-intercept of a linear function.

A cable according to an embodiment of the present invention uses a conductive material selected by the method of selecting a flexible conductive material according to the first to fourth embodiments.
For example, in the case of producing a cable (wire diameter of 80 μm) which withstands a cable bending test of 1,000,000 times or more, first of all, an SN curve prepared in advance for various bending resistant conductive materials In the data, the lower limit of the existence range of the SN curve of the bendable conductive material that withstands a cable bending test of 1,000,000 or more times from the regression line which linearly approximated the finite life area in the range of 10 ⁶ to 10 ⁷ times Y = -21.5 Ln (x) + 455, which is higher stress side than y 455, indicates the lower limit of the existence area of the SN curve of the flexible conductive material that withstands over 5,000,000 cable bending tests y = -Select a regression line present on the lower stress side than-21.5 Ln (x) + 475. In addition, when the strand of a cable differs from 80 micrometers, it exists in the high stress side from y = -21.5Ln (x) +455+ (z-80) / 2, and y = -21.5Ln (x) +475+ ( Select a regression line that exists on the lower stress side than z-80) / 2.
Then, the flexible conductive material corresponding to the selected regression line is a candidate material for forming the strands of the cable that can withstand one million or more cable bending tests.

When producing a cable (wire diameter of 80 μm) that withstands a cable bending test of 5 million times or more, the limited life range of 10 ⁶ to 10 ⁷ times of the SN curve prepared in advance is Among the linear approximation regression lines, the presence of the SN curve of a flexible conductive material which is on the higher stress side than y = -21.5 Ln (x) +475 and withstands over 10,000,000 cable bending tests A regression line existing on the lower stress side than y = −21.5 Ln (x) +505 indicating the lower limit of the region is selected. In addition, when the strand of a cable differs from 80 micrometers, it exists in the high stress side rather than y = -21.5Ln (x) +475+ (z-80) / 2, and y = -21.5Ln (x) +505+ ( Select a regression line that exists on the lower stress side than z-80) / 2.
Then, the flexible conductive material corresponding to the selected regression line is a candidate material for forming a strand of a cable that can withstand 5 million or more cable bending tests.

When producing a cable (wire diameter of 80 μm) that withstands a cable bending test of 10 million times or more, the finite life area in the range of 10 ⁶ to 10 ⁷ times of the previously prepared SN curve is Among the linear approximation regression lines, the presence of the SN curve of a flexible conductive material which is on the higher stress side than y = -21.5 Ln (x) +505 and withstands over 25 million cable bending tests A regression line existing on the lower stress side than y = −21.5 Ln (x) +560 indicating the lower limit of the region is selected. In addition, when the strand of a cable differs from 80 micrometers, it exists in the high stress side rather than y = -21.5Ln (x) +505+ (z-80) / 2, and y = -21.5Ln (x) +560+ ( Select a regression line that exists on the lower stress side than z-80) / 2.
Then, the flexible conductive material corresponding to the selected regression line is a candidate material for forming the strands of the cable that withstands 10 million or more cable bending tests.

When producing a cable (wire diameter of 80 μm) that withstands a cable bending test of 25 million times or more, the finite life area in the range of 10 ⁶ to 10 ⁷ times of the previously prepared SN curve is From the linearly approximated regression lines, a regression line present on the higher stress side than y = −21.5 Ln (x) +560 is selected. In addition, when the strand of a cable differs from 80 micrometers, the regression line which exists in the high-stress side from y = -21.5Ln (x) +560+ (z-80) / 2 is selected. Then, the flexible conductive material corresponding to the selected regression line is a candidate material for forming a strand of a cable that can withstand 25 million or more cable bending tests.

Next, experimental examples carried out to confirm the effects of the present invention will be described below.
(Experimental example 1)
A member with a length of 30 mm, a width of 3 mm, and a thickness of 0.3 mm is manufactured from a copper material for electric wire (hereinafter referred to as copper material A), and the diameter is 0.5 mm at the widthwise center position of 24 mm from one end of the member. A circular hole was formed. Subsequently, the surface of the member in which the circular hole was formed was mirror-finished, and the test piece was produced. Subsequently, the holder was attached to the other end of the test piece such that the tip of the holder was 1 mm from the center of the circular hole, and one end of the test piece was downward and the holder was fixed to the voice coil portion of the acoustic speaker . Then, the voice coil was vibrated so that the test piece was in the primary resonance state, and the fatigue test was performed. In addition, the maximum stress occurring at the holder root of the test piece was obtained from the equation of bending stress of the cantilever, and it was taken as the stress amplitude at the time of fatigue test. The fatigue test results in a finite life region of 10 ⁶ to 10 ⁷ stress cycles are shown in FIG. Further, a regression line obtained by linearly approximating a finite life region in the range of 10 ⁶ to 10 ⁷ times was y = −21.5 Ln (x) +470.

In FIG. 4, there is a regression line that linearly approximates the 10 ⁶ to 10 ⁷ finite life region in the SN curve of the flexible conductive material that withstands one million or more and five million or more cable bending tests. The functional expression which shows the lower limit of a field is shown, respectively. The regression line y = −21.5 Ln (x) +470 is the lower limit of the region of existence of the SN curve of the flexible conductive material that withstands one million or more cable bending tests. Y = −21.5 Ln (x ) + 455 (Functional equation (1)), which exists on the high stress side, but indicates the lower limit of the existence range of the SN curve of a flexible conductive material that can withstand 5 million or more cable bending tests y = -21 .5 Ln (x) + 475 (function formula (2)) exists on the low stress side. Therefore, when the cable bending test of the cable manufactured using the copper material A is performed, although it can be estimated that the number of breakages exceeds 1,000,000, it can be estimated that the number of breakages is less than 5,000,000.

On the other hand, a cable with a cross-sectional area of 0.2 mm ² made of a wire made of copper material A and having a wire diameter of 80 μm is used as a test body, and a bending radius of 15 mm with a load of 100 g applied to the test body. As a result of conducting the cable bending test by adding the left-right repeated bending whose bending angle range is ± 90 degrees, the number of breakages was 4.5 million times. Therefore, the lower limit of the region where there is a regression line that linearly approximates the 10 ⁶ to 10 ⁷ finite life region of the SN curve of a flexible conductive material that withstands one million or more and 5 million or more cable bending tests The copper material A is used by comparing functional equations (1) and (2) indicating values with regression lines that linearly approximate 10 ⁶ to 10 ⁷ finite life regions of the SN curve of the copper material A. It was confirmed that the number of breakages of the cable bending test using the cable manufactured could be predicted.

(Experimental example 2)
The same fatigue test as in Experimental Example 1 was performed using a copper material for electric wire (hereinafter referred to as copper material B) other than the copper material of Experimental Example 1. The fatigue test results in a finite life region of 10 ⁶ to 10 ⁷ stress cycles are shown in FIG. In addition, a regression line obtained by linearly approximating the finite life region in the range of 10 ⁶ to 10 ⁷ times was y = −4.8 Ln (x) +119.
The regression line y = −4.8 Ln (x) +119 of the copper material B indicates the lower limit of the existence region of the SN curve of the bending resistant conductive material that withstands one million or more cable bending tests. Y = −21. Since it exists on the low stress side according to 5Ln (x) + 455 (function formula (1)), when the cable bending test of the cable manufactured using the copper material B is performed, the number of breakages can be estimated to be less than 1,000,000 times.
On the other hand, when a cable bending test similar to Experimental Example 1 is carried out with a cable having a cross-sectional area of 0.2 mm ² made of a wire made of copper material B and having a wire diameter of 80 μm used as a test body, the number of breakages is It was 2000 times. Therefore, a functional expression indicating the lower limit value of the region where a regression line that linearly approximates the 10 ⁶ to 10 ⁷ finite life region of the SN curve of a flexible conductive material that withstands a cable bending test of 1,000,000 or more times (1) and the regression line that linearly approximates the 10 ⁶ to 10 ⁷ times finite life region of the SN curve of copper material B by comparing the regression line of the cable bending test using the cable manufactured with copper material B It was confirmed that the number of breaks can be predicted.

(Experimental example 3)
The same fatigue test as in Experimental Example 1 was performed using pure copper having a purity of 99.9% (hereinafter referred to as copper material C). A regression line which linearly approximates a finite life region of 10 ⁶ to 10 ⁷ stress cycles is shown in FIG. Further, the regression line obtained by linearly approximating the finite life region in the range of 10 ⁶ to 10 ⁷ times was y = −20.7 Ln (x) +455.
The regression line of the copper material C shows the lower limit of the existence region of the SN curve of the flexible conductive material which withstands a cable bending test of 1,000,000 times or more y = −21.5 Ln (x) +455 (function equation (1 Since it exists immediately below the low stress side of), the number of breakages is less than 1,000,000, but it can be estimated to be close to 1,000,000.
On the other hand, when a cable bending test similar to Experimental Example 1 is carried out with a cable having a cross-sectional area of 0.2 mm ² and made of a wire made of copper material C and having a wire diameter of 80 μm used as a test body, the number of breakages is It was 900,000 times. Therefore, a functional expression indicating the lower limit value of the region where a regression line that linearly approximates the 10 ⁶ to 10 ⁷ finite life region of the SN curve of a flexible conductive material that withstands a cable bending test of 1,000,000 or more times (1) and the regression line that linearly approximates the 10 ⁶ to 10 ⁷ times finite life region of the SN curve of copper material C by comparing regression lines of cable bending test using a cable manufactured with copper material C It was confirmed that the number of breaks can be predicted.

(Experimental example 4)
The same fatigue test as in Experimental Example 1 was performed using a copper material for electric wires (hereinafter referred to as copper material D) different from that of Experimental Examples 1 and 2. The fatigue test results in a finite life region of 10 ⁶ to 10 ⁷ stress cycles are shown in FIG. Further, a regression line obtained by linearly approximating a finite life region in the range of 10 ⁶ to 10 ⁷ times was y = −35 Ln (x) +700.
The regression line of the copper material D indicates the lower limit value of the existence region of the SN curve of the flexible conductive material that withstands a cable bending test of 5 million times or more. Y = −21.5 Ln (x) +475 2) shows the lower limit of the existence area of the SN curve of the bendable conductive material which exists on the high stress side and withstands the cable bending test of 10 million times or more, y = −21.5 Ln (x) +505 ( Since it intersects with the functional equation (3), the number of breakages is 5 million or more, but can be estimated to be less than 10 million.
On the other hand, when a cable bending test similar to Experimental Example 1 is performed using a cable having a cross-sectional area of 0.2 mm ² and made of a wire made of copper D and having a wire diameter of 80 μm as a test body, the number of breakages is It was six million times. ^Thus, 10 6 to 10 ⁷ times function expression showing the lower limit of the area regression line a finite lifetime region linear approximation are present (2), (3) and, of copper material D ¹⁰ 6 to 10 ⁷ times finite It was confirmed that the number of breakages in the cable bending test using a cable made of a copper material D can be predicted by comparing regression lines that linearly approximate the life region.

(Experimental example 5)
The same fatigue test as in Experimental Example 1 was performed using a copper material for electric wires (hereinafter referred to as copper material E) different from that of Experimental Examples 1, 2 and 4. A regression line y = −28.0 Ln (x) + 594 which linearly approximates a finite life region of 10 ⁶ to 10 ⁷ stress cycles is shown in FIG.
The regression line of copper material E shows the lower limit value of the existence area of the SN curve of a flexible conductive material that withstands a cable bending test of 5 million times or more, y = −21.5 Ln (x) +475 (function formula 2) shows the lower limit of the existence area of the SN curve of the bendable conductive material which exists on the high stress side and withstands the cable bending test of 10 million times or more, y = −21.5 Ln (x) +505 ( Since it exists immediately below the functional expression (3), it is possible to estimate that the number of breakages is close to 10 million.
On the other hand, when a cable bending test similar to Experimental Example 1 is carried out with a cable having a cross-sectional area of 0.2 mm ² made of a wire made of copper material E and having a wire diameter of 80 μm used as a test body, the number of breakages is It was nine million times. Therefore, a functional expression indicating the lower limit value of the region where a regression line that linearly approximates the 10 ⁶ to 10 ⁷ finite life region of the SN curve of a flexible conductive material that withstands a cable bending test of 10 million times or more (3) By comparing the regression line that linearly approximates the 10 ⁶ to 10 ⁷ times finite life range of the copper material E, it is possible to predict the number of breakages of the cable bending test using the cable manufactured with the copper material E Was confirmed.

(Experimental example 6)
The same fatigue test as that of Experimental Example 1 was performed using a copper material for electric wires (hereinafter referred to as copper material F) different from that of Experimental Examples 1, 2, 4, and 5. A regression line y = −29.2 Ln (x) + 535 which linearly approximates a finite life region of 10 ⁶ to 10 ⁷ stress cycles is shown in FIG.
The regression line of the copper material F shows the lower limit of the existence region of the SN curve of the flexible conductive material which withstands 10 million or more cable bending tests, y = −21.5 Ln (x) +505 (function equation (3 ) Shows the lower limit value of the SN curve presence area of the flexible conductive material that is on the high stress side and withstands over 25 million cable bending tests, y = -21.5 Ln (x) + 560 ( As it exists below the functional equation (4), the number of breakages can be estimated to be close to 25 million.
On the other hand, when a cable bending test similar to Experimental Example 1 is carried out with a cable having a cross-sectional area of 0.2 mm ² made of a wire made of copper material F and having a wire diameter of 80 μm used as a test body, the number of breakages is It was 24 million times. Therefore, the lower limit of the region where there is a regression line that linearly approximates the 10 ⁶ to 10 ⁷ finite life region of the SN curve of a flexible conductive material that withstands 10 million times or more and 25 million or more cable bending tests The cable produced with the copper material F was used by comparing the functional equations (3) and (4) showing the values with the regression line that linearly approximates the 10 ⁶ to 10 ⁷ times finite life region of the copper material F It was confirmed that the number of breaks in the cable bending test can be predicted.

(Experimental example 7)
When a cable with a cross-sectional area of 0.2 mm ² constructed using a wire made of copper material C and having a wire diameter of 100 μm is used as a test body, the same cable bending test as in Experimental Example 1 is performed with 500,000 breakages. It was times.
Here, when a cable having a wire diameter of 80 μm withstands a cable bending test of 1,000,000 times or more, the 10 ⁶ to 10 ⁷ finite life region in the SN curve of the bending resistant conductive material is linearly approximated. The lower limit value of the region where the regression line exists is y = -21.5 Ln (x) + 455. Therefore, when the wire diameter of the wire at the cable bending test is 100 μm, the function indicating the lower limit value The equation is corrected to y = -21.5 Ln (x) +455+ (100-80) /2=-21.5 Ln (x) +465. On the other hand, in the fatigue test using the copper material C, a regression line linearly approximating a finite life region of 10 ⁶ to 10 ⁷ times of stress repetition number is y = −22.8 Ln (x) +480. Then, as shown in FIG. 6, a functional expression y = −21.5 Ln (x) +465 showing the lower limit value corrected in the case of the wire diameter 100 μm and 10 ⁶ to 10 ⁷ times of the limited life region of the copper material C Comparing the fitted regression line y = -22.8Ln (x) +480, the regression line of the copper material C is a functional expression y = -21.5Ln (x) +465 indicating the lower limit value corrected in the case of the wire diameter 100 μm. Of the cable bending test can be estimated to be less than 1 million times, which is consistent with the cable bending test.

(Experimental example 8)
When a cable bending test similar to Experimental Example 1 is performed on a cable having a cross-sectional area of 0.2 mm ² and constructed using a wire made of copper material C and having a wire diameter of 50 μm, the number of breakages is It was 2 million times.
Here, when a cable having a wire diameter of 80 μm withstands a cable bending test of 1,000,000 times or more, the 10 ⁶ to 10 ⁷ finite life region in the SN curve of the bending resistant conductive material is linearly approximated. The lower limit value of the region where the regression line exists is y = -21.5 Ln (x) + 455. Therefore, if the wire diameter of the wire at the cable bending test is 50 μm, the function indicating the lower limit value The equation is corrected as y = -21.5 Ln (x) +455+ (50-80) /2=-21.5 Ln (x) +440. On the other hand, in the fatigue test using the copper material C, a regression line linearly approximating a finite life region in which the stress cycle number is 10 ⁶ to 10 ⁷ is y = −17.9 Ln (x) +392. Then, as shown in FIG. 6, a functional expression y = −21.5 Ln (x) +440 showing the lower limit value corrected in the case of a wire diameter of 50 μm and 10 ⁶ to 10 ⁷ times of the limited life region of copper material C Comparing regression line y = -17.9Ln (x) +392 to be approximated, the regression line of copper material C is a functional expression y = -21.5Ln (x) +440 indicating the lower limit value corrected in the case of the wire diameter of 50 μm. The number of breakages in the cable bending test can be estimated to be one million times or more, which is consistent with the cable bending test.

(Experimental example 9)
A member with a length of 30 mm, a width of 3 mm, and a thickness of 0.3 mm from an aluminum-based material prepared by adding 0.45 mass% of zirconium, 0.2 mass% of silicon, and 0.15 mass% of iron to aluminum A circular hole with a diameter of 0.5 mm was formed at a widthwise center position of 24 mm from one end of the member. Subsequently, the surface of the member in which the circular hole was formed was mirror-finished, and the test piece was produced. Subsequently, the holder was attached to the other end of the test piece such that the tip of the holder was 1 mm from the center of the circular hole, and one end of the test piece was downward and the holder was fixed to the voice coil portion of the acoustic speaker . Then, the voice coil was vibrated so that the test piece was in the primary resonance state, and the fatigue test was performed. In addition, the maximum stress occurring at the holder root of the test piece was obtained from the equation of bending stress of the cantilever, and it was taken as the stress amplitude at the time of fatigue test. The results of the fatigue test in a finite life region of 10 ⁶ to 10 ⁷ stress cycles are shown in FIG. In addition, a regression line obtained by linearly approximating the finite life region in the range of 10 ⁶ to 10 ⁷ times was y = −11.1 Ln (x) +320.

FIG. 7 is a linear approximation of the 10 ⁶ to 10 ⁷ finite life region in the SN curve of a flexible conductive material that withstands one million or more, 5 million or more, and 10 million or more cable bending tests. The functional equation which shows the lower limit value of the field where the regression line which exists is shown, respectively is shown. The regression line y = −11.1 Ln (x) +320 of the heat-treated aluminum-based material indicates the lower limit of the region of existence of the SN curve of the flexible conductive material that withstands one million or more cable bending tests. 21.5 L n (x) + 455 (Functional expression (1)), but the lower limit of the existence area of the SN curve of the bending resistant conductive material which is on the high stress side but can withstand 5 million or more cable bending tests It intersects with y = −21.5 Ln (x) +475 (function formula (2)) shown. Therefore, when the cable bending test of the heat-treated aluminum-based material is performed, the number of breakages can be estimated to exceed 1,000,000, but it can not be estimated that the number of breakages exceeds 5,000,000.

On the other hand, a cable with a cross-sectional area of 0.2 mm ² made of a heat-treated aluminum-based material and a wire diameter of 80 μm is used as a test body, and a bending radius of 100 g is applied to the test body. As a result of conducting the cable bending test by applying 15 mm and a bending angle range to right and left repeatedly bending by +/- 90 degree, the number of times of breakage was 5 million times. Therefore, the lower limit of the region where there is a regression line that linearly approximates the 10 ⁶ to 10 ⁷ finite life region of the SN curve of a flexible conductive material that withstands one million or more and 5 million or more cable bending tests Heat-treated aluminum by comparing functional equations (1) and (2) showing the values with regression lines linearly approximating the 10 ⁶ to 10 ⁷ finite life regions of the SN curve of the heat-treated aluminum-based material It was confirmed that the number of breaks in the cable bending test using the cable of the base material can be predicted.

(Experimental example 10)
The same fatigue test as in Example 1 was performed using an aluminum material (pure aluminum material) having a purity of 99%. The regression line obtained by linearly approximating the finite life region in the range of 10 ⁶ to 10 ⁷ times was y = −4.8 Ln (x) +119.
As shown in FIG. 7, the regression line y = −4.8 Ln (x) +119 of a pure aluminum material is the lower limit of the existence region of the SN curve of a flexible conductive material that withstands one million or more cable bending tests. Since it exists on the low stress side from y = -21.5Ln (x) + 455 (function formula (1)) showing, the number of breakages can be estimated to be less than 1,000,000 times when a cable bending test of a pure aluminum material is performed .
On the other hand, when a cable bending test similar to that of Example 1 is performed on a cable having a cross-sectional area of 0.2 mm ² made of a pure aluminum material and using a wire with a wire diameter of 80 μm, the fracture occurs. The number of times was 2000 times. Therefore, a functional expression indicating the lower limit value of the region where a regression line that linearly approximates the 10 ⁶ to 10 ⁷ finite life region of the SN curve of a flexible conductive material that withstands a cable bending test of 1,000,000 or more times (1) and the number of breaks in the cable bending test using a cable of pure aluminum material by comparing the regression line that linearly approximates the 10 ⁶ to 10 ⁷ finite life region of the SN curve of the pure aluminum material It was confirmed that the can be predicted.

(Experimental example 11)
Aluminum-based material (Al-Zr-Fe-Si-Ti-based material) manufactured by adding 0.75 mass% of zirconium, 0.33 mass% of iron, 0.30 mass% of silicon, 0.04 mass% of titanium to aluminum The same fatigue test as in Example 1 was performed using A regression line obtained by linearly approximating a finite life region in the range of 10 ⁶ to 10 ⁷ times was y = −16.6 Ln (x) +460.
As shown in FIG. 7, the regression line y = −16.6 Ln (x) +460 of the Al—Zr—Fe—Si—Ti based material is S of the flexible conductive material that withstands 10 million or more cable bending tests. A flexible conductive material which is present on the high stress side from y = −21.5Ln (x) +505 (functional formula (3)) indicating the lower limit of the region where the −N curve exists, and which can withstand 25 million or more cable bending tests Of the Al-Zr-Fe-Si-Ti based material because it exists on the low stress side from y = -21.5 Ln (x) +560 (functional formula (4)) which indicates the lower limit of the existence range of the SN curve of In the cable bending test, the number of breakages can be estimated to be 10 million or more and less than 25 million.
On the other hand, a cable having a cross-sectional area of 0.2 mm ² made of a wire made of an Al-Zr-Fe-Si-Ti material and having a wire diameter of 80 μm is the same as that of Example 1. When the cable bending test was performed, the number of breakages was 20 million times. Therefore, functional equations (3) and (4) indicating the lower limit value of the region where a regression line exists that linearly approximates 10 ⁶ to 10 ⁷ finite life regions, and Al-Zr-Fe-Si-Ti materials It was confirmed that the number of breaks in the cable bending test using a cable of Al-Zr-Fe-Si-Ti material can be predicted by comparing regression lines that linearly approximate 10 ⁶ to 10 ⁷ finite life regions. The

(Experimental example 12)
The aluminum-based material melted by adding 0.75 mass% of zirconium, 0.33 mass% of iron, 0.30 mass% of silicon, and 0.04 mass% of titanium to aluminum is quenched at a cooling rate of 10 ° C / min or more Texture-controlled Al-Zr-Fe-Si-Ti material produced by processing for 80% reduction in area, aging treatment at 350 ° C for 5 hours, and further processing for 80% reduction in area The same fatigue test as in Example 1 was performed using The regression line obtained by linearly approximating the finite life region in the range of 10 ⁶ to 10 ⁷ times was y = −14.8 Ln (x) +471.
As shown in FIG. 7, the regression line of the structure-controlled Al-Zr-Fe-Si-Ti material is the lower limit of the existence region of the SN curve of the flexible conductive material that withstands over 25 million cable bending tests. Since it exists on the high stress side of y = −21.5 Ln (x) +560 (function formula (4)) indicating, it can be estimated that the number of breakages is 25 million or more.
On the other hand, a cable having a cross-sectional area of 0.2 mm ² made of a wire having a wire diameter of 80 μm and made of a structure-controlled Al-Zr-Fe-Si-Ti material was tested using When the same cable bending test was performed, the number of breakages was 50 million times. Therefore, a functional expression that indicates the lower limit value of the region where a regression line that linearly approximates the 10 ⁶ to 10 ⁷ finite life region of the SN curve of a flexible conductive material that withstands a cable bending test of 25 million or more times (4) By comparing the regression line linearly approximating the 10 ⁶ to 10 ⁷ finite life regions of the SN curve of the structure controlled Al-Zr-Fe-Si-Ti material, the structure controlled Al- It was confirmed that the number of breaks in the cable bending test using a cable of Zr-Fe-Si-Ti material can be predicted.

Although the present invention has been described above with reference to the examples, the present invention is not limited to the configurations described in the above examples, and is within the scope of the matters described in the claims. It also includes other examples and modifications that can be considered.
Furthermore, combinations of the components included in the present embodiment and other embodiments and modifications are also included in the present invention.
For example, the method of a cable bending test can apply methods other than the method shown to the present Example.
In addition to the metal material, conductive plastic can be used as the conductive material.
Furthermore, instead of the stress amplitude shown on the vertical axis of the SN curve, a strain amplitude may be employed.

In the method of selecting a flexible conductive material according to the present invention, a test piece prepared using a conductive material used for a cable without conducting a dynamic drive test of the cable (for example, a ± 90 degree left-right bending test) Since a regression line can be obtained which linearly approximates 10 ⁶ to 10 ⁷ finite life regions in the SN curve obtained by conducting the fatigue test used, the cable life can be estimated based on this regression line. It becomes possible to search for a novel conductive material excellent in bending resistance quickly and easily. As a result, it is possible to quickly and inexpensively provide a cable that appropriately meets the required characteristics of bending resistance.

Claims (6)

1. From the SN curve showing the relationship between the number of breaks and the stress amplitude obtained by conducting a fatigue test of a conductive material, this conductive material is selected by a method of selecting a flexible conductive material that can withstand a dynamic drive test of 1,000,000 times or more. There,
   In the range of the stress repetition number up to 10 ⁶ to 10 ⁷ breakages in the SN curve of the conductive material, the finite life region of fatigue failure obtained by setting the stress amplitude value to y MPa and the stress repetition number to x is a straight line It is based on the fact that the approximated regression line is within the range indicated by the lower limit value y = -21.5 Ln (x) + 455 as a selection standard.
2. From the SN curve showing the relationship between the number of breaks and the stress amplitude obtained by conducting a fatigue test of a conductive material, this conductive material is selected by a method of selecting a flexible conductive material that can withstand 5 million or more dynamic drive tests. There,
   In the range of the stress repetition number up to 10 ⁶ to 10 ⁷ breakages in the SN curve of the conductive material, the finite life region of fatigue failure obtained by setting the stress amplitude value to y MPa and the stress repetition number to x is a straight line It is based on the fact that the approximated regression line is within the range indicated by the lower limit value y = -21.5 Ln (x) + 475 as a selection standard.
3. From the SN curve showing the relationship between the number of breaks and the stress amplitude obtained by conducting a fatigue test of a conductive material, this conductive material is selected by a method of selecting a flexible conductive material that can withstand a dynamic drive test of 10 million times or more. There,
   In the range of the stress repetition number up to 10 ⁶ to 10 ⁷ fractures in the SN curve of the conductive material, the finite life region of fatigue failure obtained by setting the stress amplitude value to y MPa and the stress repetition number to x is a straight line It is based on the fact that the approximated regression line is within the range indicated by the lower limit value y = -21.5 Ln (x) + 505 as a selection standard.
4. From the SN curve showing the relationship between the number of breaks and the stress amplitude obtained by conducting a fatigue test of a conductive material, this conductive material is selected by a method of selecting a flexible conductive material that can withstand 25 million or more dynamic drive tests. There,
   In the range of the stress repetition number up to 10 ⁶ to 10 ⁷ fractures in the SN curve of the conductive material, the finite life region of fatigue failure obtained by setting the stress amplitude value to y MPa and the stress repetition number to x is a straight line It is based on the fact that the approximated regression line is within the range indicated by the lower limit value y = -21.5 Ln (x) + 560 as a selection standard.
5. The method according to any one of claims 1 to 4, wherein the function formula is a cable in which the test body used for the dynamic drive test is a wire with a wire diameter of d μm. In the selection of the flexible conductive material that withstands the above-mentioned dynamic drive test of the cable which is set corresponding to the wire and composed of a wire with a wire diameter of z μm, A method of selecting a flexible conductive material, characterized in that the functional equation is corrected by adding a correction value calculated by 2) / 2).
6. A cable using a conductive material selected by the method of selecting a flexible conductive material according to any one of claims 1 to 5.

Images