JPH07229875A - Flaw inspection device for tubular member made of carbon fiber-reinforced plastic - Google Patents

Abstract

PURPOSE:To provide a device inspecting the breakage of the fibers of a carbon fiber- reinforced plastic tubular product such as a golf shaft or a fishing rod in a non- destructive manner. CONSTITUTION:A plurality of excitation coils 9a-12a selectively allowing an induction current to flow in every direction of the reinforcing fibers of a carbon fiber-reinforced plastic tubular member 1 and a plurality of detection coils 9b-12b forming pairs with respect to the coils 9a-12a are arranged to coil bobbins 9-10 and connected to an eddy current flaw detector 8. The tubular member 1 is attached to a rotary mechanism 3 through a holding part 2 and the rotary mechanism 3 is fixed to a scanning mechanism 4. When an inspection start command is inputted to a computer part 7, the scanning mechanism 4 is operated by the command of the computer part 7 to allow the tubular member 1 to run. The impedance change of the detection coils 9b-12b is converted into voltage by the eddy current flaw detector 8 while the voltage is recorded and displayed on the computer part 7. Next, the tubular member 1 is rotated by a predetermined angle and, thereafter, the same scanning is performed and these operations are repeated until the tubular member 1 makes one revolution and whole surface inspection is automatically executed and an inspection result is displayed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber breakage inspection apparatus for carbon fiber reinforced plastic tubular bodies such as golf shafts and fishing rods.

[0002]

2. Description of the Related Art Conventionally, as a method for detecting fiber breakage of a carbon fiber reinforced plastics (hereinafter referred to as CFRP) tubular body, Japanese Patent Laid-Open No. 5-107231 discloses "a method for detecting defects in a carbon fiber reinforced tubular composite material". A method using an eddy current flaw detection method is disclosed. However, this method is limited in its ability to use a through-type coil for the excitation and detection coils and to conduct an inspection by passing an eddy current in the circumferential direction of the CFRP tubular body. That is, the CFRP tubular body is a laminated material of a plurality of prepregs in which the directions of the reinforcing fibers are different, and the electrical conductivity of the prepregs is smaller by about 3 to 4 digits in the fiber direction than in the orthogonal direction. The fiber breakage of the prepreg whose direction is the circumferential direction can be detected, but the fiber breakage of the other prepregs is difficult to detect, or the detection sensitivity is significantly reduced.

Therefore, the present inventors applied for a method for solving the above problems as Japanese Patent Application No. 5-342003. According to this method, an exciting coil wound in a rectangular shape is used, and the long side direction of the exciting coil is made to coincide with the high conductivity direction (fiber direction), whereby an induced current is selectively flown in the same direction. Can detect flaws. Therefore, in the flaw detection of the laminated material, if the long side of the exciting coil is aligned with the fiber direction for each fiber direction and the flaw is detected, the breakage can be detected with high sensitivity regardless of the fiber direction. However, when the invention of the above-mentioned prior application is applied to the CFRP tubular body and the long side direction of the exciting coil is made to coincide with each fiber direction to detect flaws over the entire length and the entire circumference, there is a problem that a considerable time is required.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and rapidly inspects the fiber breakage of the CFRP tubular body in each fiber direction over the entire length and the entire circumference with high sensitivity. An object of the present invention is to provide a defect inspection apparatus that enables the above.

[0005]

In order to solve the above problems, a defect inspection apparatus for a CFRP tubular body according to the present invention comprises a plurality of devices for selectively passing an induced current in each direction of the reinforcing fibers of the tubular body. Excitation coil, an eddy current flaw detector for flowing a high-frequency current through the excitation coil and measuring impedance change, a mechanism for holding the tubular body and rotating it in the circumferential direction, and scanning the tubular body in the longitudinal direction. And a computer unit for controlling the rotation and scanning mechanism, the eddy current flaw detector, and computing and displaying the inspection result for each direction of the reinforcing fiber. Also, a plurality of detection coils paired with the exciting coil are separately provided.

[0006]

The present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory view showing an embodiment of the device of the present invention, in which an exciting coil and a detecting coil are respectively provided. A CFRP tubular body 1 (for example, a golf shaft or a fishing rod) laminated with four types of prepregs having fiber directions of 0 °, ± 45 °, and 90 ° penetrates a cylindrical bobbin 9, 10, 11, 12, respectively. Run. The tubular body 1 is attached to the rotating mechanism 3 via the holding portion 2, and the rotating mechanism 3 is fixed to the scanning mechanism 4.

As shown in FIG. 2, on the outer peripheral surface of each of the cylindrical bobbins described above, an excitation for selectively flowing an induced current in the fiber directions of 0 °, 90 °, + 45 °, and −45 °. The coils 9a, 10a, 11a, 12a are arranged, and the detection coil 9b, on the inner peripheral surface of the cylindrical bobbin,
10b, 11b, 12b are arranged respectively. The axial direction of the tube is 0 ° and the circumferential direction is 90 °. The excitation coil and the detection coil are respectively connected to a 4-channel eddy current flaw detector 8, and the eddy current flaw detector 8 converts the impedance change of each of the detection coils into a voltage and outputs the voltage.

Next, the inspection procedure by the apparatus of the present invention will be described. First, after the CFRP tubular body 1 is held by the holding unit 2, when an instruction to start the inspection is input to the computer unit 7, the instruction of the computer unit 7 is added to the drive circuit 6 and the scanning mechanism 4 causes the CFRP tubular body 1 to run. After the impedance change of each detection coil 9b, 10b, 11b, 12b is converted into a voltage change by the eddy current flaw detector 8,
The result is displayed after being recorded in the computer unit 7 and subjected to a predetermined calculation.

By the way, each of the detection coils has a characteristic that the sensitivity decreases as the defect position deviates in the circumferential direction from directly below the detection coil as shown in FIG. CFRP according to the characteristics of the detection coil
It is necessary to change the angle of the tubular body 1 for inspection.

Therefore, in the apparatus of the present invention, when one scan is completed, a command from the computer section 7 is applied to the drive circuit 5 to operate the rotating mechanism 3 to rotate the CFRP tube body 1 around the axis by a predetermined angle. The same scanning as described above is performed. By repeating these operations until the CFRP pipe 1 makes one revolution, the entire surface inspection is automatically performed.

The operation of the device having both the exciting coil and the detecting coil has been described above. However, the detecting sensitivity, resolution, etc. of the device having only the exciting coil and detecting a defect from the impedance change of the exciting coil are slightly different. However, the essential effect is the same.

[0012]

EXAMPLE With the apparatus configuration shown in FIG. 1, there are two prepregs each having an outer diameter of 25 mm, a wall thickness of 1.4 mm and a length of 1000 mm, and the fiber directions are + 45 °, −45 °, 0 ° and 90 ° in this order from the inside.
CFRP tubing consisting of a total of 8 layers was examined. A 20 × 30 mm rectangular coil was used as an exciting coil, and a differential coil in which two 6 × 10 mm rectangular coils were arranged was used as an inspection coil. The circumferential detection characteristic of the inspection coil is ± 15
It is -3 dB in °.

FIG. 4 shows an example of the inspection result, which is 12 every 30 °.
The results obtained by scanning twice are shown in a bird's-eye view, and the figures (a), (b), (c), and (d) show the detection coils 9b and 1b.
The voltage output is proportional to the impedance change of each of 0b, 11b, and 12b. As shown in FIG. 4 (a), the breakage of the fiber in the 0 ° direction is about 300 mm in the longitudinal direction and about 180 ° in the circumferential direction, and +4 from (c) and (d) in the same figure.
It was estimated that the fiber breaks in the 5 ° and −45 ° directions were about 700 mm and 270 °. Then, when the above-mentioned position of this CFRP pipe body was broken and observed, it was verified that fiber breakage had occurred corresponding to the inspection result.

In the above embodiment, the case where the CFRP tube is rotated and scanned is shown. However, even if the exciting and detecting coils are moved, the same effect is obtained. It is also possible to reduce the number of rotations by providing a plurality of exciting and detecting coils for each direction.

[0015]

As described above, according to the present invention, an induced current is selectively flown in each direction of the reinforcing fiber, and the CFRP tubular body is repeatedly scanned until it makes a round by changing a predetermined angle in the circumferential direction. Since it is configured as described above, the fiber breakage of the CFRP tubular body having a plurality of fiber directions can be inspected at high speed and automatically regardless of the direction of the broken fibers, and the defect position and its size in each direction can be quantitatively inspected. Therefore, the present invention is very effective as a product inspection device for CFRP golf shafts and fishing rods.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a device of the present invention.

[FIG. 2] In the present invention, 90 °, 0 °, + 45 °, -4
FIG. 5 is an explanatory view showing a plurality of exciting coils for selectively passing an induced current through fibers in 5 ° directions and a plurality of detecting coils forming a pair with the exciting coil group.

FIG. 3 is a diagram showing an example of circumferential detection characteristics of a detection coil according to the present invention.

FIG. 4 is a diagram showing an example of an inspection result according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CFRP tubular body 2 Holding part of CFRP tubular body 3 Rotation mechanism 4 Scanning mechanism 5 Driving circuit of rotation mechanism 6 Driving circuit of scanning mechanism 7 Computer part 8 Eddy current flaw detector 9, 10, 11, 12 Coil bobbin 9a, 10a, 11a, 12a Excitation coil 9b, 10b, 11b, 12b Detection coil

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuhiro Aikawa 5-10-1, Fuchinobe, Sagamihara-shi, Kanagawa Inside the Electronics Research Laboratory, Nippon Steel Corporation (72) Inventor Tomohiro Nakanishi 15-1 Shinshin, Kisarazu-shi, Chiba New Nippon Steel Chemical Co., Ltd. Product Development Center

Claims (2)

[Claims] 1. A plurality of exciting coils for selectively passing an induced current in each direction of a reinforcing fiber of a carbon fiber reinforced plastic tubular body, an eddy current flaw detector, and the tubular body in a longitudinal direction thereof. A scanning mechanism for scanning, a rotating mechanism for rotating the tubular body in its circumferential direction, a computer for controlling the eddy current flaw detector, the scanning mechanism and the rotating mechanism and displaying an inspection result were provided. A defect inspection apparatus for a tubular body made of carbon fiber reinforced plastics, which is characterized in that 2. The defect inspection apparatus for a carbon fiber reinforced plastic tubular body according to claim 1, comprising a plurality of detection coils paired with a plurality of exciting coils.