JP2000214138A - Method and apparatus for ultrasonic flaw detection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an erroneous detection caused by the spray or the like of a medium liquid or a coolant to the propagation passage of surface waves when a defect such as a crack or the like on the surface of a cylindrical or columnar material to be inspected is detected by a method wherein a cover which covers the whole of a holding mechanism is installed and a gas flow toward the outside of the cover from the inside of the cover is formed. SOLUTION: A cover 10 which covers the whole of a holding mechanism part 40 in an apparatus is installed, Thereby, creeping, into the holding mechanism part 40 of the spray, of a medium liquid, generated in its removal due to a scraper 70, the spray of a coolant for grinding and the mist, of the coolant for grinding, generated at a time when the coolant for grinding comes into contact with a whetstone which is rotated at high speed is cut off. In addition, a gas pipe 12 is attached to the cover 10. When a gas flow to the outside of the cover 10 is formed it is possible to prevent the mist of the coolant, for grinding, from creeping into the holding mechanism part 40 from the gap between the cover 10 and a rolling roll 110. In addition, the liquid drop of the medium liquid which is splashed by the roll is washed away to the outside of the cover 10 by the gas flow. Thereby, it is possible to prevent the liquid drop from being dropped onto the propagation passage of surface waves.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flaw detection method for detecting defects such as cracks on the surface of a cylindrical or columnar test material such as a rolling roll or a roller, or cracks existing immediately below the surface using surface waves. Related to the device.

[0002]

2. Description of the Related Art Japanese Patent Laid-Open No. 4-276 discloses a method for detecting a defect such as a crack existing on or immediately below a surface of a rolling roll or a roller.
As can be seen from 547, an ultrasonic flaw detection method using surface waves (referred to as surface wave flaw detection) is used. In this surface wave flaw detection, a surface wave probe (also called a probe) is brought into contact with the surface of a rotating cylindrical body through a film of a couplant (also called a medium liquid) such as water, and the surface wave probe While propagating the surface wave in the direction opposite to the cylinder rotation direction,
The couplant film is removed from the surface of the cylindrical body where the surface wave propagates, and defects existing on the surface of the roll and directly below the surface are detected.

An ultrasonic flaw detector using surface wave flaw detection disclosed in Japanese Patent Laid-Open No. 4-27647 is disclosed in Japanese Patent Laid-Open No. 7-29.
4493.

[0004]

However, the flaw detection method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 4-27647 and the Japanese Patent Application Laid-Open No.
The ultrasonic flaw detector disclosed in 294493 has a problem that when a droplet (medium liquid) falls on a propagation path of a surface wave, a reflected wave having a large amplitude is generated from the droplet and is erroneously detected as a defect.

In the flaw detection method and the flaw detection apparatus, a medium liquid (contact medium) such as water as an ultrasonic transmission medium is supplied between the ultrasonic probe and the surface of the test material. After finishing its role as an ultrasonic transmission medium, it is dragged by the rotation of the test material, most of which remains on the roll surface and rotates with the test material. 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 removed by the scraper. There is a case where a reflected wave having a large amplitude is generated from the acoustic wave and jumps into the propagation path of the surface wave, and is erroneously detected as a defect.

Also, in the ultrasonic flaw detector disclosed in FIG. 1 of Japanese Patent Application Laid-Open No. 7-294493, a 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 mechanism, and this roller jumps up the medium liquid that rotates with the test material, and the jumped-up droplets fall on 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.

[0007] Japanese Patent Application Laid-Open No. 7-294493 discloses a grinding apparatus for grinding the surface of a roll to be inspected by a grindstone.
In many cases, surface wave flaw detection according to Japanese Patent Application Laid-Open No. 4-27647 is carried out on a roll which has been subjected to grinding and is equipped with an ultrasonic flaw detector as disclosed in Japanese Patent Application Laid-Open No. HEI 4-27647. For example, extra time for flaw detection is not required, and the grinding efficiency of the roll is improved. Therefore, recently, flaw detection during grinding has been studied.
However, grinding with a grinding wheel of a rolling roll is performed while supplying a liquid called a coolant between a grinding wheel rotating at a high speed and the rolling roll. Phenomena such as jumping into the path or contacting the grindstone rotating at high speed, and the mist-like coolant condensing on the holding mechanism of the flaw detector, forming droplets and falling on the surface wave propagation path, occur. It is not uncommon that erroneous detection frequently occurs due to coolant droplets that have fallen on the surface wave propagation path.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and is intended to eliminate defects such as cracks or the like existing on the surface of a cylindrical or columnar test material such as a rolling roll or a roller or a surface just below the surface. An object of the present invention is to prevent erroneous detection due to a drop of a medium liquid or a coolant onto a propagation path of a surface wave when the detection is performed by a wave.

[0009]

According to the present invention, a surface wave probe for transmitting and receiving a surface wave via a medium liquid is brought into contact with the surface of a rotating cylindrical or columnar test material. In the ultrasonic flaw detection method for detecting a defect by transmitting a surface wave from the probe to the test material and receiving a reflected wave from a defect existing directly below the surface or the test material surface, By providing a cover that covers the entire holding mechanism that holds the surface wave probe so as to maintain a constant interval with respect to the surface of the test material, by forming a gas flow from inside the cover to outside the cover, This has solved the above-mentioned problem.

[0010] The present invention also provides an ultrasonic flaw detector.
A rotating means capable of rotating a cylindrical or columnar test material in a circumferential direction thereof, and a surface wave probe capable of detecting a defect or the like by emitting a surface wave on the test material surface. A holding mechanism for holding the probe so as to maintain a constant interval with respect to the surface of the test material; and a water or coolant (a coolant can also be used as a medium liquid) serving as an ultrasonic transmission medium. A medium liquid supply unit for supplying a medium liquid between the probe and the surface of the test material, a cover covering the entire holding mechanism, and a gas flow for forming a gas flow from inside the cover to outside the cover. By providing a pipe, the above-mentioned problem is also solved.

As shown in FIGS. 1 and 2, the ultrasonic flaw detector according to the present invention has a cover 10 for covering the entire holding mechanism 40.
And a gas pipe 12 for introducing a gas such as compressed air into the cover 10 so as to form a gas flow from the inside of the cover 10 to the outside of the cover 10.

The cover 10 is formed into a mist due to contact with a high-speed rotating grindstone during splashing generated when the medium liquid is removed by the scraper (70), splashing of the coolant for grinding during flaw detection during grinding, and flawing during grinding. It has a role of blocking the intrusion of the changed grinding coolant into the holding mechanism 40. However, the test material, for example, rolling roll 1
Since the outer diameter of the cover 10 varies within a certain range, the cover 10
It is not possible to completely seal the inside of the holding mechanism 40 only by itself, and there is always a gap between the cover 10 and the surface of the rolling roll 110, and the mist-like coolant is removed from the inside of the holding mechanism 40. Invade. Therefore, the gas pipe 12 forcibly creates a gas flow from the inside of the cover 10 to the outside of the cover 10 so that the cover 10
The mist-like coolant for grinding is prevented from entering the holding mechanism section 40 from the gap between the roller and the surface of the rolling roll 110.

[0013] The gas flow also prevents the droplets jumped up by the roller from falling on the surface wave propagation path. That is, the rollers are located on both sides of the surface acoustic wave probe 20 (FIG. 2).
Is located on both sides of the surface acoustic wave probe 20 in a direction perpendicular to the paper surface, but the droplets jumped up by the roller are:
It is swept away by the gas flow from the center where the surface acoustic wave probe 20 is located toward the cover 10 and does not fall on the surface acoustic wave propagation path near the surface acoustic wave probe 20.

It is preferable that the gas pipe 12 has, for example, a U-shaped tip, and that the introduced gas is once blown to the inner surface of the cover 10 near the center of the ceiling. This makes it possible to generate a gas flow having a flow rate equal to or greater than a predetermined value in all directions from the center of the cover 10 to the outside of the cover 10.

By combining the cover 10 and the gas pipe 12 for introducing gas such as compressed air into the cover 10 as described above, it is possible to detect the droplets generated when the medium liquid is removed by the scraper and the flaw detection during grinding. The droplets of the coolant and, when performing flaw detection during grinding, it is possible to prevent the coolant of the grinding coolant coming into contact with the grindstone rotating at a high speed from entering the holding mechanism portion 40, and the roller Thus, the droplet of the medium liquid that has been splashed up can be prevented from falling on the surface propagation path.

[0016]

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

In the present embodiment, as shown in FIG. 2, a medium liquid such as water or a coolant serving as an ultrasonic wave propagation medium is supplied between the surface acoustic wave probe 20 and the rolling roll 110 as a test material. Applied to the device. In particular, a description will be given of an example suitable for performing the flaw detection by scanning and moving the surface acoustic wave probe 20 on the surface of the rolling roll 110.

In this embodiment, a roll rotating device, a surface acoustic wave probe 20, a probe holder 30, and a medium liquid supply device 80
It has.

The roll rotating device is adapted to move a rolling roll 110, which is a material to be inspected for surface defects, in a circumferential direction S
It is possible to rotate it. A well-known appropriate device may be used as the roll rotating device, and is not illustrated in order to avoid complication of the drawing.

The surface wave probe 20 can detect a surface defect of the rolling roll 110 by transmitting a surface wave to the surface of the rolling roll 110.

The probe holder 30 includes a rolling roll 1
The holding mechanism 40 is provided below the guide 60 slidable with respect to the fixed structure 50 located above the holding mechanism 40. The holding mechanism section 40 is provided with a total of four rollers 42, one pair in front and back, and when performing flaw detection, these rollers 42 abut on the surface of the rolling roll 110 and rotate, so that flaw detection is performed. Stabilize scanning. The probe holder 30 is mounted between the four rollers 42.

The fixed structure 50 is provided with a motor 52 for supplying power for moving the holding mechanism 40 up and down along the guide 60, and a mounting base 54 for the motor 52. As a method of transmitting the power of the motor 52, a conventionally known appropriate means may be used, and illustration thereof is omitted to avoid complication of the drawing.

In front of the holding mechanism 40 (right side in FIG. 2)
Is provided with a scraper 70 for removing the medium liquid remaining on the surface of the rolling roll 110 so that the medium liquid does not flow into the surface wave propagation path. The scraper 70 is provided outside the cover 10.

The probe holder 30 includes a holding mechanism 4
By interposing an elastic body such as a spring between the rolling roll 110 and the rolling roll 110, the rolling roll 110 is urged and supported in the surface direction. More specifically, the probe holder 30 is attached to the tip of a rod 44 that is loosely fitted to the holding mechanism 40 so as to be slidable up and down, and a spring (not shown) is provided at an appropriate position around the rod 44. Therefore, the probe holder 30 is always urged downward.

The probe holder 30 is provided with the surface acoustic wave probe 20.
In order to form a predetermined gap between the rolling roll 110 and the rolling roll 110,
A pair of copying rollers 32 protruding to the 0 side are provided. Specifically, as shown in FIG. 3, the probe holder 30 is provided with a horizontal shaft 34, and the copying roller 32 is provided on the horizontal shaft 34. In this way, the copying roller 32 supported by the probe holder 30 is always in contact with the surface of the rolling roll 110 under the bias of the spring. With this configuration, the probe holder 30 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.

As shown in detail in FIG. 4, a medium liquid supply device 80 is provided inside the probe holder 30. The medium liquid supply device 80 includes a conduit 82, a housing 84,
The discharge port 86 is formed. The medium liquid supply device 80
Temporarily stores a medium liquid such as water or a coolant introduced from a conduit 82 in a housing portion 84 and discharges the medium liquid from a discharge port 86 provided at a bottom portion of the housing portion 84, so that the surface acoustic wave probe 2
A layer of the medium liquid without bubbles is formed between the rolls 0 and 110. Since the medium liquid supply device 80 may be configured by using a conventionally known appropriate means, a detailed description is omitted.

According to the present invention, the cover 10 for covering the entire holding mechanism 40 of the ultrasonic flaw detector configured as described above is provided. Spray of grinding coolant during flaw detection and intrusion of grinding coolant mist generated by the grinding coolant coming into contact with a high-speed rotating grindstone during flaw detection during grinding. Shield. Further, a gas pipe 12 is attached to the cover 10, and a gas such as compressed air is guided from an air supply device (not shown) to form a gas flow from the inside of the cover 10 to the outside of the cover 10. When performing flaw detection, cover 1
The mist of the coolant for grinding is prevented from entering the holding mechanism 40 from the gap between the roll 0 and the roll 110. Furthermore,
By the above-described gas flow, the droplets of the medium liquid that have been jumped up by the roller are pushed out of the cover 10 to prevent the droplets from falling onto the surface wave propagation path.

[0028]

EXAMPLE FIG. 5 shows the result of checking the surface defects of 100 rolling rolls after the completion of grinding using the above embodiment and confirming the presence or absence of erroneous detection. In order to examine the degree of improvement over the prior art, the same number of rolling rolls were inspected even in the conventional state without the cover and gas injection to check for erroneous detection. From FIG. 5, it can be seen that erroneous detection is significantly reduced in the ultrasonic inspection apparatus according to the present invention.

Also, using the above-described embodiment, surface defects were inspected during grinding at the final finishing stage of 100 rolling rolls, and the result of checking for erroneous detection is shown in FIG.
Shown in In order to examine the degree of improvement over the prior art, the same number of rolling rolls were inspected even in the conventional state without the cover and gas injection to check for erroneous detection. As is clear from FIG. 6, in the ultrasonic flaw detector according to the present invention, there is almost no erroneous detection even during flaw detection during grinding, and particularly when flaw detection is performed during grinding, the present invention is often indispensable. I understand.

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-described embodiment, water or a coolant is used as a medium liquid, and compressed air is used as a gas for forming a gas flow from the inside of the cover to the outside of the cover.
The type of the contact medium or the gas is not limited to this, and for example, another liquid such as oil may be used as the contact medium, or nitrogen gas or the like may be used as the gas.

The object of application of the present invention is not limited to rolling rolls, but can be similarly applied to other cylinders or cylinders such as rollers made of metal or the like.

[0033]

According to the present invention, when detecting a defect such as a crack or the like existing under the surface or just below the surface of a cylindrical or columnar test material by the surface wave, the medium liquid is transmitted to the propagation path of the surface wave. Erroneous detection caused by spraying of water or coolant or dropping of liquid droplets can be prevented, and the reliability of flaw detection can be improved. or,
Surface wave flaw detection can be performed even during grinding of the rolling roll, and the grinding efficiency of the rolling roll can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main configuration of the present invention.

FIG. 2 is a front view showing the overall configuration of the embodiment of the present invention.

FIG. 3 is a side view showing a probe holder part of the embodiment.

FIG. 4 is a cross-sectional view showing the same medium liquid supply device.

FIG. 5 is a diagram comparing the presence of erroneous detection when a surface defect is inspected after the completion of grinding in the embodiment and the conventional example.

FIG. 6 is a graph comparing the presence or absence of erroneous detection when a surface defect is inspected during grinding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Cover 12 ... Gas pipe 20 ... Surface wave probe 30 ... Probe holder 32 ... Copying roller 40 ... Holding mechanism part 42 ... Roller 80 ... Medium liquid supply device 110 ... Rolling roll (test material)

Continuing from the front page (72) Inventor Kazutaka Takada 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Inside the Kawasaki Steel Research Institute (72) Inventor Ryoichi Sugimoto 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Kawasaki Steel Co., Ltd. (72) Inventor Hiroo Sakuma 1st Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Inside Kawasaki Steel Corporation Chiba Works (72) Inventor Kazuyuki 2068-3 Ooka, Numazu City, Shizuoka Prefecture Toshiba Machine Co., Ltd. (72) Inventor: Tamotsu Kanehiro 1-5-5, Sakuragawa, Itabashi-ku, Tokyo Inside of Japan Clout Kramer Co., Ltd. (72) Inventor: Masao Kyoya 1-9-29, Kakuda, Higashiosaka-shi, Osaka Japan Clout Kramer Co., Ltd. F term (reference) 2G047 AB01 AD03 BA03 BC08 CB03 EA11 GE03

Claims (2)

[Claims] 1. A surface wave probe for transmitting and receiving a surface wave through a medium liquid film is brought into contact with the surface of a rotating cylindrical or columnar test material, and the surface wave probe detects the surface wave. An ultrasonic flaw detection method for detecting a defect by transmitting a surface wave to a material and receiving a reflected wave from a defect existing directly below the surface of the test material or the surface, wherein the surface wave probe A cover for covering the entire holding mechanism for holding the probe so as to maintain a constant distance with respect to the surface of the test material, and forming a gas flow from inside the cover to outside the cover. Sonic flaw detection method. 2. A rotating means capable of rotating a cylindrical or columnar test material in a circumferential direction thereof, and a surface capable of detecting a defect or the like by emitting a surface wave on the surface of the test material. A wave probe, a holding mechanism for holding the probe so as to maintain a constant interval with respect to the surface of the test material, and a probe and a test material for transferring a liquid serving as an ultrasonic transmission medium. Medium liquid supply means for supplying between the surface and the cover, a cover covering the entire holding mechanism, and a pipe for forming a gas flow from inside the cover to outside the cover. Ultrasonic flaw detector.