JP6373471B1 - Inspection method and inspection apparatus for fiber reinforced composite cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection method and an inspection apparatus for a fiber reinforced composite material cable which can be inspected efficiently and with high accuracy while having a simple configuration.
A fiber reinforced composite cable 100 including a strand 101 made of a conductive fiber reinforced composite material is inspected for damage such as breakage of the strand 101 by measuring a value related to the capacitance. To do. The coil 2 composed of the strands 2 a disposed along the circumferential direction C of the strand 101 is disposed with a predetermined gap with respect to the outer peripheral surface of the strand 101. An alternating voltage is applied to the coil 2 to cause dielectric polarization between the coil 2 and the strand 101. A value related to the capacitance due to dielectric polarization is measured by the coil 2. Based on the measurement result, the presence or absence of damage such as breakage of the strand 101 is inspected.
[Selection] Figure 1

Description

  The present invention relates to a fiber reinforced composite cable inspection method and inspection apparatus. More specifically, a fiber-reinforced composite material for inspecting whether or not the strand is broken by measuring a value related to capacitance in a fiber-reinforced composite material cable including a strand made of a conductive fiber-reinforced composite material. The present invention relates to a cable inspection method and an inspection apparatus.

  Conventionally, as an inspection method as described above, for example, the one described in Patent Document 1 is known. In this inspection method, an alternating voltage is directly applied to the strands with adjacent strands as a set, and a value related to the capacitance between the strands is measured. Therefore, in this method, if there is an insulation failure (short circuit) between the strands, there is a possibility that capacitance does not occur between the strands and the inspection accuracy may be lowered. In addition, when the damage is large, current does not flow downstream from the damaged portion, so that the downstream inspection may be difficult. Furthermore, in order to obtain the damage result of the whole cable, the combination of the strands must be changed and measured many times, and improvement in workability has been desired. Moreover, if the strands are coated, an operation for exposing the strands is required, and the workability is further reduced.

JP 2013-167602 A

  In view of such conventional circumstances, an object of the present invention is to provide a fiber-reinforced composite cable inspection method and inspection device that can be efficiently and highly accurately inspected with a simple configuration. .

  In order to achieve the above object, the feature of the fiber reinforced composite cable inspection method according to the present invention relates to the capacitance in the fiber reinforced composite cable including strands made of conductive fiber reinforced composite. In the method for inspecting the presence or absence of damage such as breakage of the strand by measuring the value, a coil made of strands arranged along the circumferential direction of the strand is provided with a predetermined gap with respect to the outer peripheral surface of the strand. The strand is arranged over the entire circumference of the strand, and the coil is relatively moved in the axial direction of the strand while the strand is inserted, and an AC voltage is applied to the coil. Dielectric polarization is generated between the coil and the strand, and the change in the capacitance due to the dielectric polarization is measured by the coil, and the measurement result It is to inspect the presence or absence of the damage based.

  According to the above configuration, the coil composed of the strands arranged along the circumferential direction of the strand is arranged with a predetermined gap with respect to the outer peripheral surface of the strand, and an AC voltage is applied to the coil to thereby apply the coil and the strand. Since dielectric polarization is generated between the two, a capacitance can be locally generated with respect to the strand. Therefore, the entire strand (cable) can be inspected at one time regardless of the insulation state between strands and the degree of damage, and the accuracy does not deteriorate. Moreover, since inspection can be performed by generating a capacitance from the outside of the strand regardless of the presence or absence of a covering material, workability is good and inspection efficiency is good. In addition, since the strands are arranged over the entire circumference of the strand and the coil is relatively moved in the axial direction of the strand while the strand is inserted, for example, in manufacturing a fiber-reinforced composite cable, the strand (cable ) Can be inspected over the entire length of the strand, and the working efficiency is extremely high.

  A pair of the coils may be provided at an appropriate interval in the axial direction of the strand, and the presence or absence of the damage may be inspected based on an output difference between the pair of coils. Thereby, the noise (backlash noise) generated by the change in the gap (relative distance) between the coil and the strand can be suppressed, and the inspection accuracy can be further improved.

  In any one of the configurations described above, the cable may be configured by a single strand, and the cable may be configured by a plurality of the strands. In this case, the one strand may be covered with a covering material, and the gap may include the thickness of the covering material. The plurality of strands may be covered with a covering material, and the gap may include the thickness of the covering material.

  In order to achieve the above object, the feature of the fiber reinforced composite cable inspection apparatus according to the present invention relates to the capacitance in the fiber reinforced composite cable including strands made of conductive fiber reinforced composite. In the configuration for inspecting the presence or absence of damage such as breakage of the strand by measuring the value, the strand consists of strands arranged along the circumferential direction of the strand, and has a predetermined gap with respect to the outer peripheral surface of the strand. And a coil that is disposed over the entire circumference of the strand, and a jig that holds the strand so as to be relatively movable in the axial direction of the strand, with the strand inserted. AC application means for applying an alternating voltage to the coil to generate dielectric polarization between the coil and the strand, and a change in the capacitance due to the dielectric polarization. Serial measured in coils, is to have a judging means for judging whether the damage on the basis of the measurement result.

  A pair of the coils may be provided at an appropriate interval in the axial direction of the strand, and the determination means may determine the presence or absence of the damage based on an output difference between the pair of coils.

  According to the characteristics of the fiber reinforced composite cable inspection method and inspection apparatus according to the present invention, it is possible to inspect efficiently and with high accuracy while having a simple configuration.

  Other objects, configurations, and effects of the present invention will become apparent from the following embodiments of the present invention.

It is the schematic which shows the inspection method of the fiber reinforced composite material cable which concerns on this invention. It is sectional drawing of the fiber reinforced composite material cable used as test object. It is a block diagram of the inspection device concerning the present invention. It is a bridge circuit diagram. It is a figure explaining dielectric polarization. It is an equivalent circuit diagram. It is a figure explaining an example of an inspection method. It is a figure which shows an example of the measurement signal of the reference | standard test body corresponding to a normal product. It is a figure which shows an example of the measurement signal of the reference | standard test body corresponding to a damaged article. It is a figure which shows an example of the coil which concerns on other embodiment of this invention. It is a figure which shows an example of the other test object of this invention.

Next, the present invention will be described in more detail with reference to FIGS.
A fiber reinforced composite cable (hereinafter simply referred to as “cable”) to be inspected according to the present invention includes a strand 101 made of a conductive fiber reinforced composite. For example, as shown in FIG. 2, the cable 100 in the present embodiment is configured as a stranded wire by arranging six strands 101 around a central strand 101 in a substantially point symmetrical manner and twisting them together. The outer periphery is covered with a covering material 102 made of a resin material such as vinyl chloride.

  The strand 101 is composed of several tens of thousands of carbon fibers 101a each having a size of about several μm, and is consolidated (impregnated) with a resin 101b such as thermoplastic resin. The thickness (wall thickness) of the covering material 102 is, for example, about 1 mm for the cable 100 having an outer diameter of φ8 mm and about 2-3 mm for the cable 100 having an outer diameter of φ12 mm. This thickness becomes a part G1 of the gap G between the outer peripheral surface 101x of the strand 101 as the inspection object and the coil 2 described later. Examples of the fiber reinforced composite material include carbon fiber reinforced plastic (CFRP). In addition, in this specification, a cable includes some flexible things, such as a wire and a rope.

  As shown in FIG. 1, an inspection device 1 for a cable 100 according to the present invention generally includes a coil 2 that is inserted through a strand 101, and an AC voltage applied to the coil 2 to generate a dielectric between the coil 2 and the strand 101. An eddy current flaw detector 3 having an oscillator 31 as an alternating current application means for generating polarization and measuring a value related to capacitance due to dielectric polarization with the coil 2 and a strand based on the measurement result of the eddy current flaw detector 3 The signal processing device 4 is provided as a determination unit that determines whether or not there is damage such as breakage of the 101.

  As shown in FIG. 1, the coil 2 is a self-inductive coil composed of a strand 2 a (winding) disposed along the circumferential direction of the strand 101. This coil generates an alternating electric field and detects a change in capacitance with the same coil. The coil 2 in the present embodiment includes a pair of first and second coils 21 and 22 that are arranged at appropriate intervals in the axial direction of the strand 101 (cable 100). When an AC voltage is applied to the first and second coils 21 and 22, the current directions are opposite to each other as shown in FIG. 5, so that the output difference can be detected. inspect. As described above, by adopting the differential method using the first and second coils 21 and 22 that make a pair, a local change such as breakage of the strand 101 can be detected with high accuracy. In addition, it is possible to cancel a gradual change such as twisting of a stranded wire as in this embodiment, and it is also possible to cancel a backlash signal of the coil 2, thereby improving detection accuracy.

  For example, as shown in FIG. 7, the first and second coils 21 and 22 are wound around the jig 10 so that the strands of the coils 21 and 22 can be disposed over the entire circumference of the cable 100 (strand 101). Yes. The jig 10 also functions as a scanning unit that holds the strand 2a of the coil 2 in a state in which the strand 101 is inserted and is relatively movable in the axial direction.

As shown in FIG. 3, the eddy current flaw detector 3 generally includes an oscillator 31 as an AC application unit, a power amplifier 32, a bridge circuit 33, an amplifier 34, a synchronous detector 35, a phase shifter 36, and a filter 37. As shown in FIG. 4, the bridge circuit 33 includes a fixed resistor 33a (resistance Z ₁ ), a variable resistor 33b (resistance Z ₂ ), a first coil 21 (impedance Z ₃ ), and a second coil 23 (impedance Z _4). ).

  The AC output from the oscillator 31 is applied to the fixed resistor 33a, the variable resistor 33b, and the self-inductive first and second coils 21 and 22 of the bridge circuit 33 via the power amplifier 32. And impedance difference (DELTA) Z (Z3-Z4) of the 1st, 2nd coils 21 and 22 is output as voltage change (DELTA) V.

  The unbalanced output between the first and second coils 21 and 22 is amplified by the amplifier 34, sent to the synchronous detectors 35a and 35b, and detected together with the outputs of the phase shifters 36a and 36b. Then, the eddy current signal is taken into the signal processing device 4 via the filters 37 a and 37 b and an A / D converter (not shown), and the measurement result is displayed on the display 5. The signal processing device 4 is configured by a personal computer (PC) connected to the eddy current flaw detector 3, for example. In the present embodiment, a recorder 7 is connected to the eddy current flaw detector 3 via a rejection means 6.

  By the way, the impedance Z of the coil 2 (first and second coils 21 and 22) is represented by the following expression in the complex number display.

Since ω = 2πf, 1 / ωC becomes extremely small when the frequency f is high, and can be ignored when the object is a conductor such as a metal material. However, the carbon fiber 101a composing the strand 101 to be inspected according to the present invention has a conductivity as small as 1/10 ^{4 in the} strand direction (axial direction) as compared with a metal. Further, the carbon fiber 101a is electrically anisotropic, and the conductivity in the direction (circumferential direction) perpendicular to the axial direction is further reduced to 1/10 ⁸ compared to metal. That is, almost no electricity flows in the circumferential direction of the carbon fiber 101a.

  As shown in FIG. 1, when the coil 2 is arranged in the cable 100 including the strand 101 constituted by the carbon fiber 101 a and an alternating current is passed, an alternating electric field and a magnetic field are generated around the coil 2. In general, when the object is a metal material, an eddy current is induced in the circumferential direction of the object by an electromagnetic induction phenomenon. However, as described above, the carbon fiber 101a is electrically anisotropic and has an extremely low circumferential conductivity, so that no current flows in the originally induced circumferential direction. Therefore, the induced current in the circumferential direction that may occur in the metal material does not flow through the strand 101 that is a conductor. Therefore, in the present invention, the impedance change only needs to take into account the resistance R and capacitance (capacitance) ωC of the winding 2a in Equation 1 above.

  As shown in FIG. 5, between the first and second coils 21 and 22 as the coil 2 and the outer peripheral surface 101x of the strand 101, a gap 102 is made of resin as a gap G and a gap made of air. G2 exists as a nonconductor (dielectric). Therefore, in the cable 100 having the covering material 102 (G1) and the gap G2 (non-conductor) around the strand 101 (conductor), when the electric fields E1 and E2 are applied by the coil 2, an induced current is generated in the circumferential direction of the strand 101. Since it does not flow, a capacitance is generated between the strand 101 and the coil 2 due to dielectric polarization.

  As exemplified by the first coil 21 on the left side of FIG. 5, when the portion of the strand 101 corresponding to the coil 2 is a healthy part without the damaged part D, the stray capacitance C1 of the first coil 21 and the inductance L1 of the first coil 21 , And the electrostatic capacitances C2 and C3 between the strand 101 and the first coil 21 are considered to form an equivalent circuit as shown in the circuit diagram on the left side of FIG.

  On the other hand, as exemplified by the second coil 22 on the right side of FIG. 5, when a damaged portion D such as a fold is present in a part of the strand 101 corresponding to the coil 2, there is no conductor in the damaged portion D. Dielectric polarization does not occur in the part. In such a case, as shown in the circuit diagram on the right side of FIG. 6, the capacitances C2 and C3 between the strand 101 and the first coil 21 are released by the damaged portion D, so it is estimated that an equivalent circuit is not established. . As described above, by detecting the change in the capacitance caused by the damaged portion D of the strand 101, it is possible to inspect for the presence or absence of damage such as breakage of the strand 101 in the cable 100 with high accuracy.

Here, the inspection method of the cable 100 according to the present invention will be described.
First, a normal product (only a healthy part) and a damaged product (with a damaged part D) are prepared using the same type as the cable 100 to be inspected as a reference test body, and the test frequency, phase, gain, Determine inspection conditions such as filter and flaw detection speed. The phase is adjusted so that the backlash signal and the flaw signal appear in the X direction or the Y direction. Further, the damaged product is a product in which part or all of the strand 101 in the cable 100 is broken.

  Next, a signal is measured with the reference specimen under the set inspection conditions, and a threshold value (absolute value or pp value) is set from the measurement data. For example, a signal level which is larger than the maximum value of the measurement data of the normal product illustrated in FIG. 8A and smaller than the flaw signal of the damaged product illustrated in FIG. ). Then, for example, as shown in FIG. 7, the cylindrical jigs 10, 10 around which the first and second coils 21, 22 are wound are fixed, and fixed with a gap G to the outer peripheral surface 101 x of the strand 101. The cable 100 is inserted through the coil 2, and an alternating voltage is applied to the first and second coils 21 and 22 to cause dielectric polarization between the coils 21 and 22 and the strand 101, and the cable 110 is connected in the axial direction A. The value related to the capacitance due to dielectric polarization is measured, and when the threshold value is exceeded, it is determined that damage D such as breakage exists.

Finally, reference is made to the possibilities of other embodiments of the invention. In addition, the same code | symbol is attached | subjected to the member similar to the above-mentioned embodiment.
In the said embodiment, although the strand 2a of the 1st, 2nd coils 21 and 22 was each wound around the cylindrical jig | tool 10, the 1st, 2nd coil 21 is formed in the both ends of one cylindrical jig | tool, for example. , 22 can be wound. That is, if the strand 2a of the coil 2 is disposed over the entire circumference of the strand 101 and the strand 2a is relatively movable in the axial direction of the strand 101 with the strand 101 inserted, the above-described embodiment It is not limited.

  Moreover, in the test | inspection of the cable 100 in the said embodiment, it test | inspects by inserting the cable 100 with respect to the fixed coil 2. FIG. This can be performed as an inspection process when the cable 100 is manufactured, for example. On the other hand, when the cable 100 is incorporated in the apparatus, the both ends of the cable 100 are fixed to the apparatus, and thus the cylindrical jigs 10 and 10 as described above cannot be used.

  Therefore, for example, as shown in FIG. 9, the wire 2 a of the coils 21 and 22 may be wound using a jig 10 ′ having a semicircular shape when viewed from the front. As shown in FIG. 5B, the part 2a1 of the strands of the first and second coils 21 and 22 are locked in the groove 11 ', while the other part 2a2 of the strand is loosened downward. Then, as shown in FIG. 5A, the other portion 2a2 is placed on the jig surface 12 'by passing the jig 10' away from the part 2a1 of the strand. Thereby, it can measure (maintenance inspection), without removing the cable 100 from an apparatus, and inspection efficiency is good. 9 is merely an example, and a part 2a1 of the strand is disposed so as to cover a part of the strand 101, and the other part 2a2 of the strand is the same as the part 2a1 of the strand with respect to the strand 101. If it is the aspect which is located in the side and hold | maintains the strand 2a so that relative movement is possible in the axial direction of the strand 101, it will not be restricted to this aspect.

  In the above-described embodiment, the cable 100 is configured by twisting six strands 101 around the central strand 101 and twisting them together to form a stranded wire, and the outer periphery of the stranded wire is a resin material such as vinyl chloride. It was constituted by covering with a covering material 102 made of. However, the inspection object is not limited to this. For example, as shown in FIGS. 10A and 10C, even a cable 100 made of one strand 101 or 19 strands 101 can be inspected.

  Moreover, as shown in FIG. 10, the thing without the covering material 102 may be sufficient. As described above, since the change in the capacitance between the conductor (strand 101) and the nonconductor is detected, it can be inspected as long as the gap G can be formed as a nonconductor between the strand 101 and the coil 2. It is. In the above embodiment, the carbon fiber reinforced plastic (CFRP) has been described as an example of the fiber reinforced composite material. However, the present invention is not limited to this, and for example, a fiber reinforced fiber having the above-described electrical characteristics such as silicon carbide fiber. It may be a composite material (fiber material).

  In the above embodiment, the inspection apparatus 1 is composed of the eddy current flaw detection apparatus 3, the signal treatment apparatus 4 (personal computer) as a determination means, and the display 5. However, the present invention is not limited to this mode. For example, the inspection apparatus 1 can be configured by an eddy current flaw detector including the determination unit 4 and the display unit 5. Moreover, in the said embodiment, although the self-induction type differential system was employ | adopted, it is not restricted to this. However, the differential method is superior in terms of detection accuracy. In the above embodiment, the voltage change is output as the impedance difference, but the value related to the capacitance is not limited to this.

1: inspection device, 2: coil, 2a: wire, 3: eddy current flaw detection device, 4: signal treatment device (determination means), 5: display means, 6: rejection means, 7: recorder, 10: cure 11 ': groove part, 12': surface, 21: first coil, 22: second coil, 31: oscillator (AC applying means), 32: power amplifier, 33: bridge circuit, 33a: fixed resistor, 33b : Variable resistor, 34: Amplifier, 35: Synchronous detector, 36: Phase shifter, 37: Filter, 100: High strength fiber composite cable, 101: Strand, 101a: Carbon fiber, 101b: Resin, 101x: Outer periphery Surface, 102: coating material, A: axial direction, C: circumferential direction, D: damage (folding), E: direction of electric field, G: gap (non-conductor)

Claims (8)

A fiber reinforced composite cable for inspecting the presence or absence of damage such as breakage of the strand by measuring a value related to capacitance in a fiber reinforced composite cable including a strand made of a fiber reinforced composite having conductivity. The inspection method of
A coil composed of strands arranged along the circumferential direction of the strand is arranged with a predetermined gap with respect to the outer peripheral surface of the strand,
The strands are arranged over the entire circumference of the strand,
The coil is relatively moved in the axial direction of the strand while the strand is inserted, and an alternating voltage is applied to the coil to generate dielectric polarization between the coil and the strand.
Measure the change in capacitance due to the dielectric polarization with the coil,
A method for inspecting a fiber-reinforced composite cable, wherein the presence or absence of damage is inspected based on the measurement result. 2. The method for inspecting a fiber-reinforced composite cable according to claim 1, wherein a pair of the coils are provided at an appropriate interval in the axial direction of the strand, and the presence or absence of the damage is inspected by an output difference between the pair of coils. The said cable consists of one said strand, The inspection method of the fiber reinforced composite material cable of Claim 1 or 2. The method for inspecting a fiber-reinforced composite cable according to claim 1, wherein the cable includes a plurality of the strands. The method for inspecting a fiber-reinforced composite cable according to claim 3, wherein the one strand is covered with a covering material, and the gap includes a thickness of the covering material. 5. The fiber reinforced composite cable inspection method according to claim 4, wherein the plurality of strands are covered with a covering material, and the gap includes a thickness of the covering material. A fiber reinforced composite cable for inspecting the presence or absence of damage such as breakage of the strand by measuring a value related to capacitance in a fiber reinforced composite cable including a strand made of a fiber reinforced composite having conductivity. Inspection equipment,
A coil composed of a strand disposed along the circumferential direction of the strand, and disposed with a predetermined gap with respect to the outer circumferential surface of the strand;
A jig for disposing the strands over the entire circumference of the strand and holding the strands so as to be relatively movable in the axial direction of the strands with the strands inserted;
AC application means for applying an AC voltage to the coil to generate dielectric polarization between the coil and the strand;
An inspection apparatus for a fiber-reinforced composite material cable, comprising: a determination unit that measures a change in the capacitance due to the dielectric polarization with the coil and determines the presence or absence of the damage based on the measurement result. 8. The fiber-reinforced composite cable inspection according to claim 7, wherein a pair of the coils are provided at an appropriate interval in the axial direction of the strand, and the determination means determines the presence or absence of the damage based on an output difference between the pair of coils. apparatus.

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