JPH11326290A - Method and apparatus for ultrasonic flaw detection of cylindrical body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method and an apparatus in which an erroneous detection caused by a liquid is eliminated, and in which a defect detection signal due to a change in the texture of a material to be inspected is not generated, by a method wherein a surface-wave flaw detection and an eddy-current flaw detection are performed simultansously and a cylindrical body is judged. SOLUTION: A water gap is formed between the surface of a surface-wave probe 20 and a rolling roll 110. Then, the surface-wave probe 20 propagates surface waves onto the surface of the rolling roll 110, and it detects a surface defect on the rolling roll 110. In addition, an eddy-current flaw detecting probe 30 generates an eddy current in the rolling roll 110, it detects a change in the flow of the eddy current due to a defect, and it detects a surface defect on the rolling roll 110. Then, the defect detection signal of an ultrasonic flaw detector 22 and the defect detection signal of an eddy-current flaw detector 32, which is delayed by a delay circuit 34, are ANDed by an AND circuit 40, and its output is used as a formal defect signal. As a result, the flaw detection of a cylindrical body can be performed with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for ultrasonically detecting a cylindrical body for detecting a defect such as a crack existing on the surface of the cylindrical body of a metal such as a rolling roll or a roller, or under the surface.

[0002]

2. Description of the Related Art Defects such as cracks existing on the surface of a metal cylindrical body such as a rolling roll or a roller or directly below the surface are detected as described in JP-A-4-27647 and JP-A-5-288734. An ultrasonic flaw detection method using waves (referred to as surface wave flaw detection) has been used. In this surface wave inspection,
A surface wave probe (probe) is brought into contact with the surface of the rotating cylindrical body through a couplant such as water, and the surface wave propagates from the surface wave probe in a direction opposite to the rotating direction of the cylindrical body. At the same time, the couplant film in the portion of the surface of the cylindrical body through which the surface wave propagates is removed to detect defects existing on the surface of the cylindrical body or directly below the surface.

An ultrasonic flaw detector using the flaw detection method disclosed in Japanese Patent Laid-Open No. 4-27647 is disclosed in Japanese Patent Laid-Open No. 7-294.
493.

[0004]

However, Japanese Patent Application Laid-Open Nos. Hei 4-27647, Hei 5-288734, and Hei 7
The surface wave flaw detection disclosed in -294493 and the like has a problem that when a water drop falls on a propagation path of a surface wave, a reflected wave having a large amplitude is generated from the drop and is erroneously detected as a defect.

[0005] That is, in the surface acoustic wave flaw detection, a medium liquid such as water which is a transmission medium of the ultrasonic wave is supplied between the ultrasonic probe and the surface of the test material. After finishing the role as the transmission medium, the sample is dragged by the rotation of the roll as the test material, and most of the drag remains on the roll surface and rotates with the roll. When the medium liquid enters the propagation path of the surface wave, problems such as inhibition of the propagation of the surface wave and generation of a reflected wave occur. Therefore, the medium liquid is usually removed by a scraper. As a result, it may jump into the propagation path of the surface wave, and a reflected wave having a large amplitude may be generated from this, and may be erroneously detected as a defect.

In the ultrasonic flaw detector shown in FIG. 1 of Japanese Patent Application Laid-Open No. 7-294493, the probe is held above the test material so as to maintain a constant distance from the surface of the test material. A roller that contacts the surface of the test material is used for the holding unit, and this roller jumps up the medium liquid that rotates with the test material, and the splashed droplets fall onto the propagation path of the surface wave. ,
From this, a reflected wave having a large amplitude is generated, which may be erroneously detected as a defect.

Further, the apparatus for performing the surface wave flaw detection is mounted on a grinding apparatus for grinding the surface of a roll to be inspected with a grindstone, and the flaw detection is often performed on the finished roll. However, performing flaw detection simultaneously with the finishing pass of grinding eliminates the need for extra time for flaw detection and improves the grinding efficiency of the roll. .

However, the grinding of the rolling rolls with the grindstone is performed while a liquid called a coolant is supplied between the grindstone rotating at a high speed and the rolling rolls. Phenomena such as jumping into the wave propagation path, coming into contact with the grindstone rotating at a high speed, and causing the mist-like coolant to condense on the holding portion of the flaw detector and dropping as droplets onto the surface wave propagation path occur. It is not uncommon that erroneous detection frequently occurs due to droplets or droplets that have fallen on the propagation path of this surface wave.

On the other hand, for detecting defects such as cracks existing on the surface of the cylindrical body of metal such as a rolling roll or a roll or directly below the surface,
In the past, eddy current testing has been used for a long time. In the eddy current flaw detection, no abnormal signal is generated even if a droplet adheres to the test material, and there is no problem of erroneous detection due to liquid as in the flaw detection by the surface wave described above.

However, eddy current flaw detection has a problem in that a defect detection signal is generated due to a change in the structure, segregation, hardness, and magnetic properties of a test material. In recent years, eddy current flaw detection has been widely used in hot finish rolling of steel sheets. Since this phenomenon is remarkable in the flaw detection of the roll of the resulting high speed tool steel (generally referred to as high-speed roll), it has been disappearing particularly from the flaw detection of the rolling roll.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned conventional problems, and is intended for ultrasonic flaw detection of defects such as cracks existing on the surface of a cylindrical metal body such as a rolling roll or a roller or directly below the surface. It is an object of the present invention to prevent erroneous detection due to a liquid and to prevent a defect detection signal from being generated due to a change in the structure, segregation, hardness, or magnetic property of a test material.

[0012]

SUMMARY OF THE INVENTION The present invention is directed to a surface wave flaw detection method for detecting a defect by detecting a reflected wave from a defect of a surface wave propagated along the surface of the cylinder during ultrasonic flaw detection of the cylinder. And eddy current flaw detection that detects changes due to defects in the eddy current generated on the surface of the cylinder and detects defects at the same time.If both defects detect defects at the same position on the surface of the cylinder, there is a defect Thus, the above problem is solved.

In the surface acoustic wave detection, a surface wave probe for transmitting and receiving a surface wave through a couplant is brought into contact with the surface of the rotating cylindrical body, and the surface wave probe moves the cylindrical body in the direction of rotation. The ultrasonic wave is propagated in a direction opposite to the above, and the defect is detected by receiving a reflected wave from a defect existing on the surface of the cylindrical body or directly below the surface.

Further, the eddy current flaw is applied to the surface of a rotating cylindrical body with an eddy current flaw detection probe to detect a defect existing on the surface of the cylindrical body or immediately below the surface.

The present invention also provides a surface flaw detection device for a cylindrical body, in which a surface wave probe for transmitting and receiving a surface wave via a couplant is brought into contact with the surface of the rotating cylindrical body. Ultrasonic wave detection means for detecting the defect by transmitting a surface wave in a direction opposite to the rotation direction and receiving a reflected wave from a defect existing on the surface of the cylindrical body or directly below the surface, and a rotating cylinder. An eddy current probe is applied to the surface of the body, and eddy current flaw detection means for detecting a defect existing on the surface of the cylinder or directly below the surface. When the two flaw detection means detect a defect at the same position on the surface of the cylinder, the defect is detected. This problem has been solved by providing signal processing means for performing presence output.

As shown in FIG. 1, the flaw detector according to the present invention is provided with a surface wave probe 20 and an eddy current flaw detection probe 30, and an ultrasonic flaw detector 22 is connected to the surface wave probe 20, An eddy current flaw detector 32 is connected to the eddy current flaw detection probe 30.

The ultrasonic flaw detector 22 amplifies a signal captured by the surface acoustic wave probe 20 to a predetermined level, extracts a defect reflection wave, and when the defect reflection wave exceeds a predetermined level, detects the defect reflection wave. The presence signal is output.

The eddy current flaw detector 32 extracts a defect signal from the signal detected by the eddy current flaw detection probe 30,
When the defect signal exceeds a predetermined level, a signal indicating a defect is output.

In FIG. 1, the eddy current flaw detection probe 30 is located on the upstream side of the surface acoustic wave probe 20 when viewed from the rotation direction of the test material (rolling roll 110) indicated by the arrow C in the figure. Since the defect signal appears earlier in the flaw detection probe 30, this signal is delayed by the delay circuit 34, and a defect signal is generated due to a positional displacement between a position where the flaw detection is performed by the surface acoustic wave probe 20 and a position where the flaw detection is performed by the eddy current detection probe 30. Is corrected.

A defect detection signal of the ultrasonic flaw detector 22;
The defect detection signal output from the eddy current flaw detector 32 delayed by the delay circuit 34 is input to the AND circuit 40 and is ANDed, and the defect detection signal is output from both the ultrasonic flaw detector 22 and the eddy current flaw detector 32. A formal defect detection signal is output only when the signal is output.

With this configuration, when the signal detected by the surface acoustic wave probe 20 is an erroneous detection signal due to liquid, the eddy current flaw detector 32 which does not react to liquid is used.
Does not detect a defect detection signal, and as a result, no defect detection signal is output from the AND circuit 40. Therefore,
Erroneous detection due to liquid can be prevented. Further, even when the signal detected by the eddy current flaw detection probe 30 is any one of a change in the structure, a segregation, a change in the hardness, and a change in the magnetic properties of the test material, the ultrasonic flaw detection which does not react to any of these changes. The defect detection signal is not output from the circuit 22, and as a result, no defect detection signal is output from the AND circuit 40. Therefore, erroneous detection due to a change in the structure, segregation, hardness, and magnetic characteristics of the test material can be prevented.

As described above, only when there is a true defect, a defect detection signal is output from the ultrasonic flaw detector 22 and the eddy current flaw detector 32, and a defect detection signal is also output from the AND circuit 40. Therefore, by providing both the surface acoustic wave probe 20 and the eddy current flaw detection probe 30 in the flaw detection apparatus and determining that there is a defect only when a defect is detected at the same position, it is possible to eliminate erroneous detection.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings.

Referring to FIG. 1, a description will be given of an embodiment suitable for performing a flaw detection by scanning and moving a surface acoustic wave probe 20 and an eddy current detection probe 30 on the surface of a rolling roll 110.

In this embodiment, the roll rotating device, the surface wave probe 20, the ultrasonic flaw detector 22, the eddy current flaw detection probe 30, the eddy current flaw detector 32, and the surface wave probe holder 5 are provided.
0, an eddy current detection probe holder 51, and a water supply device 80 are provided.

The roll rotating device moves the rolling roll 110, which is to be inspected for surface defects, in the circumferential direction C
Rotate to. As the roll rotating device, a well-known appropriate device may be used, and in order to avoid complication of the drawing,
Illustration is omitted.

The surface wave probe 20 transmits a surface wave to the surface of the rolling roll 110 by forming a water gap between the surface of the surface wave probe 20 and the rolling roll 110 as an object. In addition, a surface defect of the rolling roll 10 is detected.

The eddy current inspection probe 30 generates an eddy current in the rolling roll 110 by forming a predetermined gap between the surface of the eddy current inspection probe 30 and the rolling roll 110 as an object to be inspected. By detecting a change in the flow of the eddy current, a surface defect of the rolling roll 110 is detected.

The holder 50 for the surface acoustic wave probe and the holder 51 for the eddy current detection probe are slidable with respect to the fixed structure 70 located above the rolling roll 110.
6 holding mechanism for surface acoustic wave probe attached to the lower part of 6
0 and the holding mechanism 61 for the eddy current detection probe. The holding mechanism 61 for the surface wave probe includes:
A pair of front and rear rollers, a total of four rollers 62, are provided.
When performing flaw detection, these rollers 62 and 63 abut against the surface of the rolling roller 110 and rotate to stabilize flaw detection scanning. The holder 50 for the surface acoustic wave probe is provided between the four rollers 62, and the holder 51 for the eddy current flaw detection probe is provided between the four rollers 63.

The fixed structure 70 includes the holding mechanism 6
A motor 72 for supplying power for raising and lowering 0 and 61 along a guide 76 and a mounting base 74 thereof are provided. As a method of transmitting the power of the motor 72, a conventionally known appropriate means may be used, and illustration is omitted to avoid complication of the drawing.

In front of the holding mechanism 61 for the eddy current flaw detection probe (right end in the figure), a scraper 90 for removing the couplant from the surface of the roll 110 so that the couplant remains on the surface wave propagation path is prevented. Is provided.

The holder 50 for the surface acoustic wave probe is supported by being urged toward the surface of the rolling roll 110 by interposing an elastic body such as a spring between the holder 50 and the holding mechanism 60. The eddy current detection probe holder 51 is also provided with an elastic body such as a spring between the holder 51 and the holding mechanism 61,
It is supported by being urged toward the surface of the rolling roll 110.

More specifically, the holding mechanism 60 for the surface acoustic wave probe
The surface wave probe holder 50 is attached to the tip of a rod-shaped body 66 that is freely slidably fitted up and down, and a spring (not shown) is provided at an appropriate position around the rod-shaped body 66 to always The wave probe holder 50 is urged downward.

The surface acoustic wave probe holder 20 is provided with the surface acoustic wave probe 20. A predetermined gap is formed between the surface acoustic wave probe 20 and the rolling roll 110. Also, a pair of copying rollers 52 projecting toward the lower rolling roll 110 is provided. Specifically, as shown in FIG. 2, a shaft 54 is provided along the horizontal direction of the surface acoustic wave probe holder 50, and the copying roller 52 is provided on the shaft 54.

As described above, the surface wave probe holder 50
The copying roller 52, which is rotatably supported by the roller, is always in contact with the surface of the rolling roll 110 under the bias of the spring. With this configuration, the holder 50 for the surface acoustic wave probe holds the surface acoustic wave probe 20 such that the gap between the surface acoustic wave probe 20 and the rolling roll 110 maintains a constant value.

The eddy current flaw detection probe holding mechanism 61
The eddy current flaw detection probe holder 51 is attached to the tip of a rod-shaped body 67 that is freely slidably fitted up and down, and a spring (not shown) is provided at an appropriate position around the rod-shaped body 67. The flaw detection probe holder 51 is urged downward.

The eddy current flaw detection probe holder 51 includes:
The eddy current flaw detection probe 30 is provided. In order to form a predetermined gap between the eddy current flaw detection probe 30 and the rolling roll 110, a pair of profilings projecting toward the rolling roll 110 below the eddy current flaw detection probe 30. Roller 53
Is provided. Specifically, similarly to the surface acoustic wave probe 20, a shaft 55 is provided along the horizontal direction of the eddy current detection probe holder 51, and the shaft 55 is provided on the shaft 55.
Are arranged.

As described above, the eddy current flaw detection probe holder 5
The copying roller 53, which is pivotally supported by 1, is always in contact with the surface of the rolling roll 110 under the bias of the spring. With this configuration, the eddy current flaw detection probe holder 51 holds the eddy current flaw detection probe 30 such that the gap between the eddy current flaw detection probe 30 and the rolling roll 110 maintains a constant value.
Hold.

As shown in detail in FIG. 3, a water supply device 80 is provided inside the holder 50 for the surface acoustic wave probe. The water supply device 80 temporarily stores the water guided from the conduit 82 in the storage portion 84, discharges the water from the discharge port 86 provided at the bottom of the storage portion 84, and connects the surface wave probe 20 with the rolling roll 110. In between, a water film without bubbles is formed.
Since the water supply device may be configured using conventionally known appropriate means, detailed description will be omitted.

An ultrasonic flaw detector 22 is connected to the surface acoustic wave probe 20, and an eddy current flaw detector 32 is connected to the eddy current flaw detection probe 30. The ultrasonic flaw detector 22 amplifies the signal captured by the surface acoustic wave probe 20 to a predetermined level, extracts a defect reflected wave, and outputs a signal indicating a defect when the defect reflected wave exceeds a predetermined level. Is output. The eddy current flaw detector 32 extracts a defect signal from the signal detected by the eddy current flaw detection probe 30 and outputs a signal indicating that there is a defect when the defect signal exceeds a predetermined level. The logical product of the defect detection signal of the ultrasonic flaw detector 22 and the defect detection signal of the eddy current flaw detector 32 delayed by the delay circuit 34 is calculated by the logical product circuit 40, and the output becomes a formal defect detection signal.

In the present embodiment, since the eddy current flaw detection probe 30 is provided on the upstream side of the surface acoustic wave probe 20,
The couplant supplied between the surface acoustic wave probe 20 and the rolling roll 110 does not adversely affect the detection of the eddy current detection probe 30. Note that, depending on the situation, the eddy current detection probe 30 may be provided downstream of the surface acoustic wave probe 20.

Further, in this embodiment, the output of the eddy current flaw detection probe arranged in advance is delayed by the delay circuit 34, so that the positional deviation from the output of the surface acoustic wave probe 20 is corrected, and the logical product of both is corrected. , A defect signal is output, and the configuration is simple. Note that the method of delaying the output of the preceding probe and the method of detecting that a defect has been detected by both the surface wave inspection and the eddy current inspection are not limited thereto.

[0043]

FIG. 4 shows the results of checking the number of detected defects and the number of erroneous detections of 50 rolling rolls by using the above-described embodiment, after the completion of grinding, for 50 rolls. In order to investigate the degree of improvement over the prior art, the number of detected and erroneously detected defects by the surface acoustic wave probe alone and the number of detected and erroneously detected defects by the eddy current probe alone were also examined. It can be clearly seen that the flaw detector according to the present invention does not have any erroneous detection.

FIG. 5 shows the result of checking the surface defects during the grinding in the grinding finishing pass for 50 rolls by using the above embodiment and confirming the presence or absence of erroneous detection. In order to investigate the degree of improvement over the prior art, the number of detected defects and
The number of detected defects and the number of erroneous detections using only the eddy current detection probe were also examined. With the flaw detection device according to the present invention, there is no erroneous detection, and it can be clearly seen that the present invention is essential for performing flaw detection during grinding.

Although the present invention has been specifically described above, the present invention is not limited to the above-described embodiment, and can be variously modified without departing from the gist thereof.

For example, in the above embodiment, the case where water is used as the contact medium has been described, but other liquids such as oil may be used.

The application of the present invention is not limited to a rolling roll, and is not particularly limited as long as it is a cylindrical body such as a roller made of metal or the like.

[0048]

According to the present invention, when detecting defects such as cracks existing on or just below the surface of a metal cylindrical body such as a rolling roll or a roller, there is no erroneous detection caused by the liquid, and High-accuracy flaw detection can be performed without generating a defect detection signal due to a change in the structure, segregation, hardness, or magnetic property of the test material.

[Brief description of the drawings]

FIG. 1 is a front view showing an overall configuration of an embodiment of the present invention.

FIG. 2 is a side view showing a probe holder part of the embodiment.

FIG. 3 is a cross-sectional view showing the same water supply device.

FIG. 4 is a table showing the results of confirming the number of detected defects and the number of erroneous detections when flaw detection is performed after grinding is completed.

FIG. 5 shows a case where a flaw was detected during grinding in a grinding finish pass.
Chart showing the number of detected defects and the number of false detections in comparison with the conventional example

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 20 ... Surface wave probe 22 ... Ultrasonic flaw detector 30 ... Eddy current flaw detector 32 ... Eddy current flaw detector 34 ... Delay circuit 40 ... AND circuit 50 ... Surface wave probe holder 51 ... Eddy current flaw detection probe holder 60 ... Surface wave probe holding Mechanism 61: Eddy current flaw detection probe holding mechanism 70: Fixed structure 80: Water supply device 110: Rolling roll

Claims (4)

[Claims] 1. A surface wave flaw detection method for detecting a defect by capturing a reflected wave from a defect of a surface wave propagated along a surface of a cylinder, and a change due to a defect in a vortex generated on the surface of the cylinder. And an eddy current flaw detection method for detecting defects at the same time, and when both flaws detect a defect at the same position on the surface of the cylinder, it is determined that there is a defect. 2. A method for ultrasonically inspecting a cylindrical body according to claim 1, wherein said surface wave flaw detection comprises bringing a surface wave probe for transmitting and receiving a surface wave via a couplant into contact with the surface of the rotating cylindrical body. From the surface wave probe to the cylinder,
The surface wave is propagated in a direction opposite to the rotation direction, and the defect is detected by receiving a reflected wave from a defect existing immediately below the surface of the cylinder or the surface, thereby detecting the defect. Ultrasonic flaw detection method. 3. The method for ultrasonically inspecting a cylindrical body according to claim 1, wherein the eddy current flaw detection is performed by applying a eddy current flaw detection probe to the surface of the rotating cylindrical body to detect a defect existing on the surface of the cylindrical body or immediately below the surface. An ultrasonic flaw detection method for a cylindrical body, comprising: 4. A surface wave probe for transmitting and receiving a surface wave via a couplant is brought into contact with the surface of the rotating cylindrical body, and the surface wave probe is applied to the cylindrical body in a direction opposite to the rotation direction. And ultrasonic wave detection means for detecting the defect by receiving a reflected wave from a defect present on the surface of the cylindrical body or immediately below the surface, and applying an eddy current flaw detection probe to the surface of the rotating cylindrical body,
Eddy current flaw detection means for detecting a defect present on the surface of the cylinder or directly below the surface; signal processing means for outputting a defect when a defect is detected at the same position on the surface of the cylinder by the two flaw detection means; An ultrasonic flaw detector for a cylindrical body, comprising: