JPH0651864U - Hot wire eddy current flaw detector - Google Patents

Abstract

(57) [Summary] [Purpose] Stable flaw detection is possible in hot magnetic saturation eddy current flaw detection. [Structure] Two inspection coils 3a and 3b are arranged on a flaw detection line 1 at a predetermined interval, magnetic saturation coils 7a and 7b are provided on both sides of the inspection coil 3b on the downstream side, and an upstream side is provided. In the hot wire eddy current flaw detector of the wire having a structure capable of controlling the magnetic saturation coils 7a and 7b based on the defect detection signal of the inspection coil 3a, the inspection coil except the coil bobbin 11 in the inspection coil 3b on the downstream side. The inlet / outlet side flange portions 12a and 12b and the inlet side guide 13a and the outlet side guide 13b of the inspection coil 3b are made of a non-magnetic material. The inlet-side guide 13a is provided with an air-purging ejection hole 14 toward the inlet-side flange portion 12a.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an improvement of an apparatus for hot eddy current flaw detection of a wire rod (including a steel bar).

[0002]

[Prior art]

 When performing eddy current flaw detection on a wire rod, the temperature of the wire rod is above the magnetic transformation point and it is in a non-magnetic state, so the effect of magnetic noise is neglected and normally stable. It is possible to detect flaws.

However, in hot eddy current flaw detection at a high temperature of 1000 ° C. or higher, there is no correlation between the defect volume and the output signal regardless of the size of the defect, although the wire is non-magnetic. This means that even in the usual hot eddy current flaw detection at 1000 ° C or higher, for example, when there is a "health flaw" in the wire, the portion is cooled when the flaw surface floats from the shape of the flaw. Since it is easy, if this temperature is below the magnetic transformation point, it is magnetized.

Therefore, in the usual hot eddy current flaw detection method, the permeability changes as a result of the “health flaw”, so that the change in the electrical resistance at the original defect is not detected, but the permeability is changed. The change is detected, and a defect signal different from the actual defect is output, resulting in overestimation.

Therefore, the present applicant has proposed Japanese Patent Application No. 3-76767 as a hot eddy current flaw detection method capable of solving the above-mentioned drawbacks. In this method, two inspection coils are arranged in the axial direction at a predetermined interval, magnetic saturation coils are provided on both sides of the downstream No. 2 inspection coil, and the No. 1 inspection coil is The magnetic saturation coil is controlled based on the defect detection signal to magnetically saturate the defective portion, and then flaw detection is performed using the No. 2 inspection coil. Even if there is a magnetic field due to a local temperature drop below the magnetic transformation point, the magnetism is erased and detected as a change in electrical resistance at the original defect.

[0006]

[Problems to be solved by the device]

 The above-mentioned method previously proposed by the applicant of the present invention, in the case of hot eddy current flaw detection at 1000 ° C. or higher, even if there is a defect such as “health flaw” whose temperature is below the magnetic transformation point, the defect volume High-precision flaw detection is possible by obtaining an output signal according to the above. However, subsequent experiments by the present inventors have shown that when magnetic saturation is applied in hot eddy-current flaw detection, "Ibarari" and It has been found that there is an inherent problem that the "scale" and the like are magnetically adhered in the inspection coil, which deteriorates the wire permeability and, in the worst case, leads to a misroll.

In view of the above-mentioned problems, the present invention provides a hot wire eddy current flaw detector for a wire which can solve the problems inherent in the hot magnetic saturation eddy current flaw detection method previously proposed by the present applicant. It is an object.

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, the hot wire eddy current flaw detector of the present invention has two inspection coils arranged on the flaw detection line at a predetermined interval and also has a downstream inspection coil. In the hot eddy current flaw detector for the wire, which has magnetic saturation coils on both sides of the wire and is configured to control the magnetic saturation coil based on the defect detection signal of the upstream inspection coil, The inlet / outlet side flange of the inspection coil excluding the coil bobbin of the coil and the inlet / outlet side guide of this inspection coil are made of non-magnetic material, and the inlet side guide is provided with an air purge jet hole toward the passage part. Of.

[0009]

[Action]

 The hot eddy current flaw detection system for wire rods of the present invention has an inspection coil input / output unit except for the coil bobbin in the downstream inspection coil of the two inspection coils arranged at a predetermined distance on the flaw detection line. Since the side flange and the guide on the inlet / outlet side of this inspection coil are made of non-magnetic material, "barr", "scale", etc. are less likely to be magnetized within the inspection coil. Even if they are magnetically attached in the inspection coil, they can be easily removed by air purging.

[0010]

【Example】

 A hot eddy current flaw detector for a wire according to the present invention will be described below with reference to an embodiment shown in the accompanying drawings. FIG. 1 is a cross-sectional view showing a downstream inspection coil and an inlet / outlet side guide which are main parts of the hot wire eddy current flaw detector for a wire of the present invention, and FIG. 2 is an overall configuration of a hot wire eddy current flaw detector for a wire of the present invention. FIG.

In FIG. 2, reference numeral 1 denotes a flaw detection line provided on the downstream side of the finish rolling mill 2. Two flaw detection coils 3a and 3b are arranged on the flaw detection line 1 at a predetermined interval. ing.

The inspection coil 3a and the eddy current flaw detector 4a arranged on the upstream side of the above-mentioned two inspection coils only need to confirm whether or not there is a surface defect in the wire rod in a high temperature state of 1000 ° C. or higher. The surface defect detected by the inspection coil 3a and its eddy current flaw detector 4a is detected in size and form by the inspection coil 3b and its eddy current flaw detector 4b arranged on the downstream side.

By the way, when the size and shape of the surface defect detected by the upstream inspection coil 3a is detected by the downstream inspection coil 3b, for example, a signal indicating that the surface defect is detected is detected on the upstream side. When the inspection coil 3a outputs the output to the control device 5, the control device 5 detects the rolling speed input from the rolling speed detector 6 and the distance between the inspection coils 3a and 3b, which is input in advance, from the downstream side. The DC power supply 8 is used to calculate the timing of energizing the magnetic saturation coils 7a and 7b, which are arranged close to each other on both sides of the inspection coil 3b, and to keep the surface defects whose size and shape are to be detected in a magnetically saturated state. The energization command is output to.

By detecting surface defects in this way, when hot eddy current testing is performed at 1000 ° C. or higher, there are defects such as “health flaws” that have a temperature below the magnetic transformation point. However, an output signal according to the volume of the defect can be obtained and highly accurate flaw detection can be performed. Then, after the size and form of the surface defect is detected by the downstream inspection coil 3b, the control device 5 issues a command to the DC power supply device 8 to stop energizing the magnetic saturation coils 7a and 7b. To do.

By the way, in the hot eddy current flaw detector for wire according to the present invention, as shown in FIG. 1, the inlet and outlet flange portions 12a and 12b of the inspection coil except the coil bobbin 11 in the downstream inspection coil 3b (see FIG. And the inlet side guide 13a and the outlet side guide 13b of the inspection coil 3b are made of a non-magnetic material such as austenitic stainless steel, and the inlet side guide 13a is provided with the inlet side flange portion 12a. That is, the air-purging jet holes 14 directed toward the above are provided.

Therefore, according to the present invention, even if eddy current flaw detection is carried out in a state where the surface defect is magnetized in the downstream side inspection coil 3b, "bare", "scale" and the like are less likely to be attached to the downstream side inspection coil 3c. Become. Further, the control device 5 outputs a command to stop the energization of the magnetic saturation coils 7a and 7b to the DC power supply device 8 and at the same time outputs an ON command to the ON-OFF switching valve 10 provided in the air purging pipe 9. For example, even if "bare" or "scale" is magnetically attached inside the inspection coil 3b, it can be easily removed to the outside of the inspection coil 3b by air purging. The ON-OFF switching valve 10 may be turned off after a certain period of time by a timer after the ON command.

[0017]

[Effect of device]

 As described above, the hot eddy current flaw detector for a wire according to the present invention uses the coil bobbin in the downstream inspection coil of the two inspection coils arranged at a predetermined interval on the flaw detection line. Except for the inlet / outlet side flange of the inspection coil and the inlet / outlet side guide of this inspection coil made of non-magnetic material, "bare", "scale", etc. are less likely to be magnetized in the inspection coil. Therefore, the wire passability does not deteriorate, and therefore stable flaw detection is possible for a long period of time, and the effect of hot magnetic saturation eddy current flaw detection is maximized. Even if "barr", "scale", etc. are magnetically attached in the inspection coil, they can be easily removed by air purging.

In the present embodiment, the control of the energization of the magnetic saturation coil is performed by the rolling speed or the like, but the tip of the wire is detected immediately after the upstream inspection coil, and the rear end is detected downstream. It may be detected immediately after the inspection coil on the side, and the magnetic saturation coil may be energized after the detection of the front end and before the detection of the rear end.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a downstream inspection coil and an inlet / outlet side guide which are main parts of a hot eddy current flaw detector for a wire according to the present invention.

FIG. 2 is an explanatory view showing the overall configuration of a hot eddy current flaw detector for a wire according to the present invention.

[Explanation of symbols]

 1 flaw detection line 3a upstream side inspection coil 3b downstream side inspection coil 4a upstream side eddy current flaw detector 4b downstream side eddy current flaw detector 5 controller 7a magnetic saturation coil 7b magnetic saturation coil 9 air purge pipe 11 coil bobbin 12a inlet side flange portion 12b Outlet flange portion 13a Inlet side guide 13b Outlet side guide 14 Jet hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Toshiyuki Tamai, No. 1 Konomi-cho, Kokurakita-ku, Kitakyushu, Fukuoka Prefecture Sumitomo Metal Industries, Ltd. Kokura Works

Claims (1)

[Scope of utility model registration request] 1. Two inspection coils are arranged on a flaw detection line at a predetermined interval, magnetic saturation coils are provided on both sides of the downstream inspection coil, and the upstream inspection coil is defective. In a hot wire eddy current flaw detector for a wire having a configuration capable of controlling the magnetic saturation coil based on a detection signal, an inlet / outlet side flange portion of an inspection coil excluding a coil bobbin in the downstream inspection coil and an insertion of the inspection coil. A hot eddy current flaw detector for a wire rod, characterized in that the outlet side guide is made of a non-magnetic material, and the inlet side guide is provided with an air-purging jet hole toward the passage portion.