JPH0328372Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an eddy current flaw detection device for wire rods that facilitates sensitivity calibration of a flaw detection coil.

For flaw inspection in the finishing process of wire, the wire is passed through a coil through which high frequency waves are passed, and if the wire has flaws, the eddy current flowing through the wire changes, which is induced in the impedance of the detection coil or in the coil. Since changes occur in the voltage, an eddy current flaw detection method is used that captures this electrical signal and determines the presence and extent of flaws based on the amplitude and phase of this signal. However, in this method, it is necessary to calibrate the sensitivity of the detection coil frequently, for example, once every 4 to 5 hours. Products obtained in inspections with insufficient sensitivity calibration and insufficient flaw detection ability are treated as low-quality products, so it is desirable to carry out sufficient sensitivity calibration. For this purpose, it is desirable to place the calibration device near the machine side of the wire production line. However, the conventional sensitivity calibration device is a method in which a rod-shaped test piece with an artificial flaw is placed inside the through-hole coil concentrically with the through-hole coil, and this test piece is moved back and forth in the axial direction of the through-hole coil for calibration. However, due to the reciprocating motion, the device became large and it was difficult to place it near the machine side.

On the other hand, while holding one side of the bar-shaped test piece 4 with the artificial flaw shown in FIGS.
A rotary drive mechanism consisting of an electric motor 1, a speed reducer 2, and a chuck 3 that rotates the through-type eddy current detection coil 5 for eddy current flaw detection, and a through-type eddy current detection coil 5 for eddy current flaw detection so that the test piece 4 is in an eccentric state. The present applicant previously filed an application for an eccentric rotation type calibrator in which a coil holder 6 for holding an eddy current detection coil 5 is provided on a base 8 (Utility Application No. 131,683/1983). Since this calibrator is rotary, the device is compact and sensitivity calibration can be performed quickly and with high reliability. The present invention aims to facilitate sensitivity calibration and perform highly accurate flaw detection by placing an eccentric rotation type calibrator near the machine side and combining it with an eddy current detection coil.

Hereinafter, an embodiment of the present invention will be described based on FIG. The wire rod 11 passes through a finishing mill 12 and advances in the direction of arrow A. A penetrating eddy current detection coil 13 for detecting flaws in the wire is usually of a cassette type, is built into a coil holder 14, and is installed at a passing position before the wire passes through. In FIG. 3, the detection coils 13, 13 are installed before and after the finishing rolling mill 2, but it is also possible to install only one of them, especially only the finishing rolling mill 2.
A processing device 15 extracts a flaw signal from the detection signal output from the detection coil 13 and performs arithmetic processing to determine the presence or absence of a flaw and its condition. This result is displayed on the display device 16. On the other hand, the coil holder 14 is normally inserted into the drawer guide 1 in a direction substantially perpendicular to the direction in which the wire passes.
7. Arrow B indicates the direction of movement of the coil holder 14. One wire passes through the coil holder 14, and during the passage of the next wire, the coil holder 14
7. An eccentric rotation type calibrator 18 is arranged adjacent to the guide 17. The calibrator 18 is movable left and right and back and forth, for example, with respect to the wire passing direction as shown by arrows C and D, and has a structure that allows easy position adjustment for calibrating the sensitivity of the detection coil 13. The eccentric rotation type calibrator 18 is used for the test piece 4 as described above.
The center of the coil 13 is adjusted to a position where the center of the coil 13 is eccentric, and calibration is performed by rotating the test piece 4. Calibration is performed in a very short time, for example, about 10 minutes at a time. ends. After calibration, the coil holder 14 is moved to the guide 1.
7 in its original position.

As described in detail above, according to the present invention, the sensitivity calibration of the flaw detection coil can be performed easily and in an extremely short time, and the quality control of the wire material is facilitated.

[Brief explanation of the drawing]

FIG. 1 is a front view of the eccentric rotation type calibrator, and FIG. 2 is a sectional view taken along the line AA in FIG. Third
The figure is a plan view for explaining an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Electric motor, 2...Reducer, 3...Chuck, 4...Test piece, 5...Eddy current detection coil, 6...
...Coil holder, 7...Guide, 8...Base, 9
... Groove, 11 ... Wire rod, 12 ... Finishing rolling machine, 1
3... Eddy current detection coil, 14... Coil holder, 15... Processing device, 16... Display device, 17
...Drawer guide, 18...Eccentric rotation type calibrator.

Claims (1)

[Scope of utility model registration request] A coil holder with a built-in penetrating eddy current detection coil for eddy current flaw detection of wire, a drawer guide for pulling out the coil holder, and sensitivity calibration of the detection coil at the pulled out position when the coil holder is pulled out along the drawer guide. An eddy current flaw detection device for wire rods, characterized in that it is combined with an eccentric rotation type calibrator that is arranged to perform