JPS5940265B2 - Thermal billet eddy current flaw detection equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal billet eddy current flaw detection device for on-line full-surface flaw detection of a cylindrical or cylindrical metal body such as a thermal billet.

Conventionally, as control data for round billet rolling, billet cracking, peeling, and poor shape were visually observed.

Because of the high rolling force and high rolling speed, it was virtually impossible to detect any flaws on the billet surface. In addition, since hot flaw detection was not possible, good materials that did not require maintenance were mistakenly passed through the refining process, which caused confusion in the flaw removal work process and caused a decline in production efficiency. I was getting used to it. In addition, as an alternative to visual inspection, a water cooling coil 1 as shown in Fig. 1 is used, and an eddy current detection circuit 2 is used to
Penetrating eddy current flaw detectors exist that detect surface flaws, but they have the following problems. That is, since a bridge balance circuit is used in the eddy current detection circuit 2, the detection ability for small defects is insufficient, and it cannot be used for sorting out good and defective materials. Furthermore, the coil 1 must be replaced every time the diameter of the material 3 to be inspected is changed, resulting in extremely poor workability. Further, as shown in FIG. 2, a probe type eddy current flaw detector is used in some cases, in which a probe coil 4 is placed close to the welded part of the welded pipe 5 and the welded part is detected by an eddy current detection circuit 6. In the conventional flaw detection circuit that also uses a bridge balanced circuit, the gap between the probe coil 4 and the material to be inspected cannot be maintained sufficiently, so the water cooling mechanism becomes extremely large, which causes problems in terms of flaw depth classification and full-surface flaw detection. There are many
In particular, it was nearly impossible to detect linear flaws and cracks in the axial direction that are unique to billets.

The purpose of this invention is to perform full-surface flaw detection of various sizes of round billets within a certain range with high sensitivity and precision, and perform online mill control based on the retrieved flaw information. The present invention provides a thermal billet eddy current flaw detection device that can significantly reduce work costs by improving flaw detection speed and accuracy and improving yield by sorting materials and marking according to the size of flaws. .

Preferred embodiments of the present invention will be described below based on the drawings.

FIG. 3 shows the basic configuration of the eddy current flaw detection device of the present invention, in which a flaw detection sensor 7 consisting of a detection coil is attached to the peripheral wall of a cylindrical rotating body 8 and rotated at a constant speed, thereby allowing heat to be transferred through the body. The entire outer peripheral surface of the billet 11 is inspected for flaws.

The signal detected by the flaw detection sensor 7 is given to a detection circuit 10 via a signal transmission device 9 using a slip ring or an electrostatic transformer, and a flaw signal is extracted. This detection circuit 10 was filed in Japanese Patent Application No. 49-1704 by the same applicant.
No. 8 and U.S. Patent No. 4,030,027, this uses the feedback amplifier circuit proposed in U.S. Patent No. 8 and U.S. Patent No. 4,030,027. , the one using the feedback amplifier circuit used in this invention has the same sensitivity of 7 to 10 m7! l
This makes it possible to eliminate the gap in temperature, thereby greatly reducing the influence of temperature caused by the thermal billet 11, and also greatly relaxing the design tolerance when attaching to the rotating body 8. Although omitted in FIG. 3, the eddy current flaw detector of the present invention transmits flaw signals to the thermal billet 1 facing the flaw detection sensor 7.
1, and automatic centering means for automatically correcting the eccentricity with respect to the axis of the rotating body 8, that is, the rotation center of the flaw detection sensor 7, due to the bending of the thermal billet 1 being transferred. It is something that you have together.

FIG. 4 shows a specific embodiment of the mechanical structure of the thermal billet eddy current flaw detection apparatus of the present invention. In FIG. 4, numeral 12 is a cylindrical body whose inner surface is coated with a heat insulating material 28, which is rotated at a constant speed by a belt hooked to a pulley 13 from a drive source such as a motor, and the thermal billet 11 is passed through the inside of the cylindrical body.

Reference numeral 14 denotes a flaw detection sensor in which a plurality of probe coils are arranged horizontally.
2, and cooling water is circulated by a water supply mechanism 26.

Furthermore, protective rolls 15 are attached to both ends of the flaw detection sensor 14 to prevent the flaw detection sensor 14 from coming into direct contact with the circumferential surface of the thermal billet 11. This flaw detection sensor 14
As shown in FIG. 5, these are attached to the cylindrical body 12 at four locations at an angle of π/2, for example. Here, if the number of flaw detection sensors 14 used is N, the feeding speed (7) of the thermal billet 11 to the flaw detector is -Nln×10-3 [m/Min] (1) However, l - flaw detection sensor Axial effective length (Mm) per probe coil constituting n-rotational speed of cylindrical body 12 (
Rpm).

Further, as is clear from FIG. 5, a first distance sensor 16 for detecting a gap between the flaw detection sensor 14 and the thermal bilge opening 1 is arranged separately, and is similarly water-cooled.

Referring again to FIG. 4, reference numeral 17 denotes a cart for rotatably supporting the cylindrical body 12, which can be moved on rails 20 by wheels 19 in a direction perpendicular to the feeding direction of the thermal billet.
2 is rotatably attached to the lifting device 18 using a bearing 25.

This trolley 10 and its elevating device 18 allow the cylindrical body 12
is movable vertically and horizontally with respect to the thermal billet 11. In this embodiment, a movable coil 21 attached to the rotating cylindrical body 12 and a support body 27 of the lifting device 18 are used as signal transmission devices for extracting the signals of the flaw detection sensor 14 and the first distance sensor 16 to the outside. Coupling means using an electrostatic transformer is used, which is comprised of a fixed coil 22 disposed with a predetermined gap to a moving coil 21.

Of course, a slip ring can also be used in place of the electrostatic transformer. 23 is a rotation angle sensor, and a lifting device 18
A pulse-like induced voltage is extracted by facing a plurality of protrusions formed at regular intervals on the circumferential side of a rotating disk 24 that is fixed to a support 27 and attached to a rotating cylindrical body 12.

That is, as shown in FIG.
A plurality of protrusions 28 and reference signal protrusions 29 are formed at zero rotation intervals, and these protrusions 28 and 29 serve as the rotation angle sensor 16.
, a voltage representing a pulsed angular position is induced. Although not shown in FIG. 4, the above-mentioned (
1) Thermal billet 1 sent at the speed (7) given by Eq.
A second distance sensor is provided to detect the flaw detection feed length of the thermal billet 11, and specifically, a pulse generator or the like may be provided in the transfer mechanism of the thermal billet 11.

Further, the water supply mechanism 26 supplies cooling water not only to the flaw detection sensor 14 but also to the cylindrical body 12 by its centrifugal force. FIG. 7 is a circuit block diagram showing an embodiment of the electrical system in the eddy current flaw detection apparatus of the present invention combined with the mechanical configuration of FIG. 4. In FIG. 7, 14 is a flaw detection sensor, 16 is a A rotation angle sensor 23 is a first distance sensor that measures the size of the rotation gap with respect to the thermal billet, and 30 is a second distance sensor that measures the flaw detection feed length of the thermal billet.

Further, 31 is an AGC circuit, 32 is a peak detector, 33 is an amplifier, 34 is an arithmetic device that takes out the flaw output together with position information, 35 is a marking device, 36 is a recording device, 37 is an automatic centering controller, and a flaw detection sensor , -14, and the eccentricity of the thermal billet with respect to the center of rotation is taken out, and the lifting device 18 of FIG.
A correction signal is sent to the vertical drive device 38 that operates the carriage 10, and the left and right drive device 39 that operates the trolley 10.

Therefore, to explain the function and operation of each circuit part, the flaw signals of the thermal billet taken out by the plurality of flaw detection sensors 14 are detected by the peak detector 32 for each flaw signal, and the peak value of the flaw signal is taken out for each flaw signal. , to the arithmetic unit 34.

On the other hand, the first distance sensor 23 detects a large gap with respect to the surface of the thermal billet, and the AGC circuit 31 detects the gap from the distance sensor 23 so that the flaw signal from the flaw detection sensor 14 does not fluctuate due to this gap variation. Automatic gain control of the peak value to be extracted by the peak detector 32 is performed based on the signal. Therefore, level fluctuations in the flaw signal caused by fluctuations in the gap between the thermal billet and the flaw detection sensor 14 are almost completely eliminated. The flaw signal extracted by the peak detector 32 is amplified to a predetermined level by an amplifier 33 and is provided to an arithmetic unit 34.

The flaw outputs input to the calculation device 34 are simply arranged on the time axis, and the positional relationship with the thermal billet is unknown. Therefore, the rotation angle sensor 16 and the second distance sensor 30
Based on the angle signal and the distance signal, the position information representing the flaw detection position at the time when the predetermined flaw signal was obtained is extracted by calculation, and the position information is sent together with the flaw output. A pen recorder or the like is used as the recording device 35, and the arithmetic device 34
By the output, the size of the flaw corresponding to the position information is displayed and recorded on a recording paper or the like. Furthermore, the marking device 36 uses a data processing device to memorize the size and position of the flaw and is activated with a predetermined time delay, marking the flaw occurrence part of the thermal billet sent after flaw detection. Mark the flaw with color-coded paint, etc. so that it can be identified according to the size of the flaw. On the other hand, the self-aligning controller 37 extracts the deviation between the distance signal from the distance sensor 23 and the distance signal determined from the angle signal from the rotation angle sensor 16 at a position 180 degrees out of phase, and this deviation is always The vertical drive device 38 and the left and right drive devices 39 are controlled so that the temperature is zero, and automatic centering control is performed so that the rotation center of the flaw detection sensor 14 always coincides with the central axis of the thermal billet even if the thermal billet is bent. ing.

The embodiment shown in FIG. 7 shows a case where the output of the eddy current flaw detection device of the present invention is used to control a marking device, but it may also be used for positioning cutting with a hot saw, and furthermore, By using it for popping out billets that have occurred, it is possible to eliminate wasteful horizontal holding on the finishing line.

In addition, the flaw information extracted by the device of this invention, that is, the flaw occurrence position, flaw occurrence rate, flaw length and depth, etc., is used to provide feedback to the mill control, and if necessary, change the reduction schedule. It is possible to implement online control to reduce the occurrence of defects in the rolling process by changing the rolls, selecting whether to increase or decrease the number of hot scarves, etc.

As explained above, since the thermal billet eddy current flaw detection device of the present invention uses a feedback amplification type for its flaw detection circuit, it is possible to maintain a sufficient gap between the thermal billet and the probe coil. Full-surface flaw detection can be performed with high accuracy and sensitivity by rotating the sensor, and the flaw detection speed can be set arbitrarily in proportion to the rotation speed of the flaw detection sensor and the number of flaw detection sensors, and can be increased in speed. Since it has a means to automatically correct the deviation of the rotation center of the flaw detection sensor due to the bending of the thermal billet, it is possible to reliably eliminate the influence of gap fluctuations in the flaw signal, and as a result, the marking of detected flaws can be improved. It is possible to automate the corresponding finishing processes such as thermal sawing and popping out the flaw riblet, and furthermore, it is possible to perform online control to reduce the occurrence of flaws by providing feedback to the mill control that causes flaws. This resulted in labor savings and improved yields on the round billet production line, and resulted in a significant reduction in overall operating costs.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing an overview of a conventional penetrating eddy current flaw detector.
Fig. 2 is an explanatory diagram showing the outline of a conventional probe type eddy current flaw detector, Fig. 3 is an explanatory diagram showing the basic configuration of the eddy current flaw detector of the present invention, and Fig. 4 is a mechanical diagram of the eddy current flaw detector of the present invention. FIG. 5 is an explanatory diagram showing the arrangement of the flaw detection sensor in the embodiment of FIG. 4, and FIG.
FIG. 7 is an explanatory diagram showing a rotating disk for angle detection in the embodiment of FIG. 4, and FIG. 7 is a circuit showing an embodiment of the electrical system of the eddy current flaw detection apparatus of the present invention, which is combined with the embodiment of FIG. 5. It is a block diagram. 1... Water cooling coil, 2, 6... Eddy current detection circuit, 3... Test material, 4... Probe coil, 5... - Connection pipe, 7...flaw detection sensor, 8...rotating body, 9...signal transmission device, 10...detection circuit, 11...・
・Thermal billet, 12... Cylindrical body, 13...
...Pulley 1, 14...Flaw detection sensor 15.
... Protection roll, 16 ... First distance sensor, 17 ... Dolly, 18 ... Lifting device, 19 ... Wheel, 20 ·····rule,
21...Rotating coil, 22...Fixed coil, 23...Rotation angle sensor, 24...
... Rotating disk, 25 ... Bearing, 26.
... Water supply mechanism, 27 ... Sensor position adjustment mechanism, 28 ... Protrusion, 29 ... Reference protrusion, 30 ... Second Distance sensor, 31.
．． ．． ．． ．． ．． AGC circuit, 32...Peak detector, 33...Amplifier, 34...Arithmetic device, 35...Recording device, 36... Marking device, 37... Automatic alignment controller, 38...
... Vertical drive device, 39... Left and right drive device.

Claims (1)

[Scope of Claims] 1. A thermal billet eddy current flaw detection device that performs full-surface flaw detection on a cylindrical metal body such as a thermal billet, comprising a cylindrical body through which a thermal billet is transferred and rotated at a constant speed by a drive source, and the cylindrical body. a flaw detection sensor arranged on the circumference of the cylindrical body to detect flaws in the thermal billet; a first distance sensor arranged on the circumference of the cylindrical body to measure a distance from the outer peripheral surface of the thermal billet; A dolly supported so as to be movably adjustable and rotatable in vertical and horizontal directions, and a signal interposed between a support portion of the dolly and the cylindrical body to form a signal path for the flaw detection sensor and the first distance sensor. a transmission device, a rotation angle sensor that detects the rotational position of the cylindrical body, a second distance sensor that detects the flaw detection feed distance in the longitudinal direction of the thermal billet, the flaw detection sensor, first and second distance sensors, and an arithmetic unit that transmits a flaw signal on the thermal billet together with positional information on the thermal billet based on each detection signal from the rotation angle sensor; 1. A thermal billet eddy current flaw detection device comprising: an automatic centering controller that detects the eccentricity of the thermal billet with respect to the vehicle and adjusts the position of the cylindrical body supported on the trolley. 2 As a flaw detection sensor placed on the circumference of a cylindrical body,
The thermal billet eddy current flaw detection device according to claim 1, having a mounting structure that can be movably adjusted or replaced according to the outer diameter of the material to be tested.