JP2001013113A - Depth measuring method of surface damaged part of rolling roll and grinding method of rolling roll by using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure accurately the depth of a thermally or mechanically damaged part of a rolling or by rolling, and thereby to optimize always a grinding quantity of the roll. SOLUTION: A rolling roll with a thermal or mechanical damage on the surface by rolling is rotated, and simultaneously a surface wave probe is brought into contact with the surface of the rolling roll through a film of contact medium. A surface wave is propagated from the surface wave probe, and a reflected wave from a thermally or mechanically damaged part existing or remaining on the surface of the rolling roll is received, and its frequency is measured, and the depth of the thermally or mechanically damaged part is measured based thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the depth of a surface damaged portion of a rolling roll and a method for grinding a rolling roll using the same. To a method suitable for

[0002]

2. Description of the Related Art Work rolls for a stand at the front stage of a hot finishing rolling mill are subjected to large thermal and mechanical shocks by rolling, and are susceptible to thermal and mechanical damage near the surface. Referring to FIG. 8 which conceptually illustrates this, thermal damage occurs due to the high temperature of the material to be rolled, and a deep crack called a heat crack extending perpendicular to the roll surface 110. A primary crack (hereinafter, referred to as a primary crack) K is generated. On the other hand, mechanical damage
It is generated by the shear stress caused by rolling with the backup roll, and is generated in the direction along the roll surface as a secondary crack (hereinafter, referred to as a secondary crack) L starting from the primary crack K. Then, when the secondary crack L grows and is connected to the primary crack K or another secondary crack L, a minute chip M is generated on the roll surface.

[0003] When the minute chipping M is transferred to the material to be rolled, it becomes a surface defect of the material to be rolled. Therefore, after being removed by grinding to a certain depth from the surface, the roll is used again for rolling. As seen in Japanese Patent Application Laid-Open No. 4-27647, ultrasonic flaw detection using a surface wave is performed. That is, a surface wave probe (probe) is brought into contact with the surface of the rotating cylindrical body through a couplant film, and the surface wave propagates from the surface wave probe in a direction opposite to the rotating direction of the cylindrical body. Then, the couplant film in the portion of the surface of the cylindrical body where the surface wave propagates is removed to detect a defect existing on the surface of the cylindrical body or directly below the surface. If a defect is detected by this flaw detection, additional grinding is performed.

[0004] In order to prevent the generation of the minute chip M, only the secondary crack may be removed by grinding (the minute chip does not occur if there is no secondary crack).

[0005] However, the above-mentioned Japanese Patent Application Laid-Open No. Hei 4-27654.
In the ultrasonic flaw detection method using the surface wave disclosed in No. 7, it is usual to use a narrow band pulse having a pulse width of about 5 times the wavelength of the surface wave, but a minute crack called a heat crack is used. When the flaw detection method is applied to a rolling roll having a generated surface, a phenomenon occurs in which the amplitude is increased due to interference of minute reflected waves from minute heat cracks due to a long pulse. In addition, it has been found that there is a problem that the remaining portion of the primary crack which does not need to be removed is excessively detected, and the roll grinding amount becomes excessive, thereby deteriorating the basic unit of roll.

Accordingly, the present inventors have proposed in Japanese Patent Application No. Hei 10-33.
Assuming that the center frequency of the surface wave transmitted and received by the surface wave probe is fc as 5347, the frequency bandwidth in which the intensity falls within a range of −6 dB with respect to the peak value in the frequency spectrum of the surface wave is set to 0. An ultrasonic flaw detection method and apparatus characterized by being 50 fc or more,
Also, before or during grinding, the height of the reflected wave of the surface wave from the above-mentioned thermally / mechanically damaged portion is measured, and based on the measured value, grinding of the thermally / mechanically damaged portion of the roll surface is performed. This problem has been solved by proposing a roll grinding method in which grinding is performed by setting the amount of grinding in the removal by grinding.

[0007]

SUMMARY OF THE INVENTION However, Japanese Patent Application No.
It has been found that the roll grinding method proposed in 335347 has the following problems. That is, the scanning roller used to form a predetermined gap between the surface wave probe and the rolling roll is worn out, or foreign matter adheres to the copying roller, and the surface wave probe and the rolling roll are When the value of the gap between them changes, or the parallelism between the surface wave probe and the rolling rolls deteriorates, the efficiency of transmission of ultrasonic waves from the surface wave probe to the rolling rolls decreases. The height of the reflected wave of the surface wave from the thermally and mechanically damaged part is proportional to the efficiency of the transmission of the ultrasonic wave from the surface wave probe to the rolling roll. The height of the reflected wave of the surface wave from the mechanically and mechanically damaged part is apparently low, and the amount of grinding determined based on the height of the reflected wave of the surface wave from the thermally and mechanically damaged part is too small. In some cases, thermal and mechanical damage was left uncut.

As similar to the present invention, Japanese Unexamined Patent Publication No. 60-235056 discloses that when estimating the depth of a defect by a surface wave, the depth of the defect is determined from the frequency distribution of the reflected signal reflected from the defect immediately below the surface of the object. It is described in Japanese Patent Application Laid-Open No. 4-54447 that data obtained by receiving an ultrasonic surface wave is frequency-divided to obtain a frequency representing the relationship between frequency and its intensity. It is described that a distribution curve is obtained, a frequency distribution area of a predetermined frequency region is calculated from the curve, and a damage amount of the material to be inspected is obtained by comparing with a master data. However, the configuration is complicated.
Further, no consideration is given to a method of extracting a reflected wave for performing frequency analysis. For example, when a plurality of reflected waves are present in the same received signal, there is also a problem that a frequency caused by a temporal separation between reflected waves is erroneously detected. Was.

Accordingly, the present invention provides a simple thermal and mechanical method that does not change the efficiency of transmission of ultrasonic waves from a surface wave probe to a rolling roll in a rolling roll whose surface has been thermally and mechanically damaged by rolling. A first object is to provide a method for measuring the depth of a mechanically damaged portion, and a second object is to optimize the amount of grinding in thermal and mechanical damage grinding of a rolling roll.

[0010]

SUMMARY OF THE INVENTION According to the present invention, a surface acoustic wave probe is provided on a surface of a rolling roll through a couplant film while rotating the rolling roll, the surface of which is thermally and mechanically damaged by rolling. Contact, propagate the surface wave from the surface wave probe, receive the reflected wave from the thermally or mechanically damaged portion existing or remaining on the surface of the roll, and only the reflected wave having an amplitude larger than a predetermined threshold value Is extracted, the frequency is measured, and the depth of the thermally / mechanically damaged portion is measured based on the extracted frequency, thereby solving the first problem.

The present invention also provides a method for grinding a roll having a surface which has been thermally and mechanically damaged by rolling, while rotating the roll before starting the grinding or during the grinding. A surface wave probe is brought into contact with the surface of the roll via a couplant film to propagate the surface wave from the surface wave probe and a reflected wave from a thermally or mechanically damaged portion existing or remaining on the surface of the rolling roll. And only the reflected wave having an amplitude larger than a predetermined threshold is extracted, its frequency is measured, and the depth of the thermally / mechanically damaged portion is measured based on the frequency. The second problem has been solved by setting the subsequent grinding amount in accordance with the depth of the mechanically and mechanically damaged portion and performing the grinding.

When the center frequency of the surface wave transmitted and received by the surface wave probe is fc, the frequency bandwidth of the surface wave probe (the width of the frequency spectrum whose intensity is within -6 dB with respect to the peak) is defined as It is 0.50fc or more.

[0013]

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

When the center frequency of the surface wave transmitted and received by the surface wave probe is fc, the present inventors show that in the frequency spectrum of the surface wave, the intensity is -6d higher than the peak.
Using a surface wave probe having a frequency bandwidth within the range of B within a range of 0.70 fc and a center frequency fc of the surface wave of 2 MHz, the frequency of the reflected wave from the thermally / mechanically damaged portion and the thermal wave were measured.・ The relationship between the depth of the mechanically damaged part and the frequency of the reflected wave from the thermally and mechanically damaged part is determined by grinding a small amount of the roll that has been thermally and mechanically damaged on the surface by rolling. Investigated by measuring. The amplitude of the reflected wave to be subjected to the frequency measurement is 1/1/1 of the amplitude of the reflected wave from a drill hole having a depth of 1 mm and a diameter of 1 mm formed on the roll surface.
More than 6 were selected. This is to prevent, when there are a plurality of reflected waves from the thermally / mechanically damaged portion, erroneously measuring a frequency caused by a time interval between the reflected waves. The result is shown in FIG. It can be clearly seen that as the depth of the thermally and mechanically damaged portion decreases, the frequency of the reflected wave from the thermally and mechanically damaged portion increases. From FIG.
The relationship between the amount of grinding required to remove the thermally and mechanically damaged portion and the frequency of the reflected wave from the thermally and mechanically damaged portion can be obtained, and this is shown in FIG.

The change in the transmission efficiency of the ultrasonic wave from the surface wave probe to the rolling roll changes the intensity of the surface wave transmitted and received by the surface wave probe, but does not affect the frequency of the surface wave. Therefore, by measuring the frequency of the reflected wave from the thermally / mechanically damaged portion before starting the grinding or during the grinding, and determining the grinding amount using the relationship of FIG. 2,
Even if the transmission efficiency of ultrasonic waves from the surface wave probe to the rolling roll changes, grinding with the appropriate grinding amount is possible, and it is possible to prevent uncut parts from thermally and mechanically damaged parts. is there.

According to FIG. 1, when the depth of the thermally / mechanically damaged portion is 0.2 mm, the frequency of the reflected wave from the thermally / mechanically damaged portion is 1.5 MHz. In general, since the depth of the thermally / mechanically damaged portion in the work roll for hot finish rolling does not exceed 0.2 mm, the center frequency fc used for measuring the depth of the thermally / mechanically damaged portion is 2 MHz. The lower limit of the frequency band of the surface acoustic wave probe may be lower than 1.5 MHz. If this lower limit value is written using the center frequency fc, it becomes fc−0.25fc. Further, since the frequency spectrum of the surface wave is substantially symmetric with respect to the center frequency fc, the frequency bandwidth when the lower limit of the frequency band is fc−0.25fc is 0.50fc. Therefore, it can be seen that if the frequency bandwidth is 0.50 fc or more, it is possible to measure the depth of the thermally and mechanically damaged portion in the hot finish rolling work roll.

An embodiment according to the present invention will be specifically described below with reference to FIG. This embodiment shows an apparatus that measures the depth of a thermally and mechanically damaged portion due to a surface wave before the start of grinding or during the course of grinding, and transmits a set value of the grinding amount to a grinding device of a rolling roll. Further, it also serves as a flaw detection device for detecting a defect existing on the surface or immediately below the surface. As a roll roll grinding device, a conventionally well-known applicable device may be used, and illustration thereof is omitted to avoid complication of the drawing.

The measuring apparatus according to the present embodiment has a reference numeral 110 in the figure.
As a basic configuration, a rolling means for rotating the roll 110 and a surface wave probe 1 for transmitting and receiving surface waves to and from the roll 110
0, a probe holder 12 for holding the probe 10, and a holder 12 for supplying a couplant (eg, water) between the surface of the roll 110 and the surface acoustic wave probe 10.
, An ultrasonic flaw detector 70 connected to the surface acoustic wave probe 10, and A / D conversion of an ultrasonic reception signal (electric signal) from the ultrasonic flaw detector 70. An A / D converter 71, a level determiner 72 that compares the A / D-converted electric signal with a predetermined threshold, and extracts a reflected wave signal equal to or greater than the threshold, and a signal output from the level determiner 72 A frequency analyzer 73 for performing frequency analysis.

Although the illustration of the rotating means is omitted to avoid complication of the drawing, the rolling roll 10 to be inspected is not shown.
Any device can be used as long as it can rotate 0 in its circumferential direction C.

The composition of the damping material of the surface acoustic wave probe 10 is adjusted so that the frequency bandwidth becomes 0.50 fc or more and surface waves having a pulse width of 2.5 wavelengths or less can be transmitted and received.

This surface acoustic wave probe 10 is
By forming a state in which water (a couplant) is filled in the gap between the sample roll 0 and the surface of the rolling roll 110 as a test object, and transmitting ultrasonic waves to the surface of the roll 110 through the water, Propagating a surface wave to the roll 110 and receiving the reflected wave to receive a reflected signal from a thermally / mechanically damaged portion of the surface of the roll 110 and a reflected signal from a surface defect of the roll 110. Is available.

The probe holder 12 holding the surface acoustic wave probe 10 is attached to a lower portion of a guide 16 slidable in a vertical direction with respect to a fixed structure portion 14 located above a rolling roll 110. It is held by the holding mechanism 18. Four rollers 20 are attached to the holding mechanism 18, and the probe holder 12 is disposed between the rollers 20. When performing the flaw detection, these four rollers 20 are rolled by the rolling rolls 110.
By rotating in contact with the surface, it functions to stabilize flaw detection scanning. A motor 14 for supplying power for moving the holding mechanism 18 up and down along the guide 16 to the fixed structure 14 via a normal transmission means (not shown).
A is fixed to the assembly base 14B.

The probe holder 12 is attached to a lower end of a rod 12A loosely fitted to the holding mechanism 18 so as to be movable up and down, and is interposed at a predetermined position around the rod 12A. It is always supported by a spring (not shown) while being urged downward in the figure, that is, against the surface of the rolling roll 110.

In order to form a predetermined gap between the surface acoustic wave probe 10 and the rolling roll 110, the probe holder 12 has a pair of protruding parts which project downward from the surface acoustic wave probe 10 toward the rolling roll 110. Copy Roller 2
2 are provided.

FIG. 4 is an enlarged front view showing this state. A shaft 24 is provided on each of both opposing sides of the probe holder 12 along the horizontal direction (roll axis direction). Each of the copying rollers 22 is rotatably mounted. Thus, the probe holder 12
The scanning roller 22 supported by the roller receives the urging force of the spring, so that the rolling roller 110 is always used during measurement.
It comes into contact with the surface, and by this configuration,
In the probe holder 12, the surface wave probe 10 is held so that a constant gap is always maintained between the surface wave probe 10 and the rolling roll 110.

In the surface acoustic wave probe 10, as shown in FIG. 5, in which the contours of the probe holder 12 and the copying roller 22 are respectively shown by two-dot chain lines and omitted, water introduced from the conduit 28 is introduced. It is possible to form a water layer without bubbles between the surface acoustic wave probe 10 and the rolling roll 110 by temporarily storing the water in the housing portion 26A and discharging it from the discharge port 26B provided at the bottom of the housing portion 26A. I can do it.

In FIG. 3, reference numeral 30 denotes a scraper, in which the water supplied by the water supply unit 26 remains on the roll surface and flows onto the surface wave propagation path as described above. It works to remove the water so that it does not occur.

The ultrasonic flaw detector 70 supplies the surface acoustic wave probe 10 with electric pulses necessary for transmitting the surface acoustic wave, and the surface acoustic wave probe 10 receives the electric pulse and converts it into an electric signal. It has the function of amplifying the reflection signal from the thermally and mechanically damaged portion and the reflection signal from the surface defect of the rolling roll 110 to a level applicable to frequency analysis and defect detection. Further, a surface defect is detected by comparing the reflected signal with a predetermined threshold value for detecting a defect or detecting the amplitude of the reflected signal.

The A / D converter 71 connected to the ultrasonic flaw detector 70 removes the surface of the rolling roll 110 amplified to an appropriate level by the ultrasonic flaw detector 70 from a thermally and mechanically damaged portion. A / D conversion of the reflected signal is performed, and a level determination unit 72
Output to The level determiner 72 compares the input digital data with a specified threshold, and outputs only digital data of a reflected wave having an amplitude equal to or larger than the threshold to the frequency analyzer 73.

The frequency analyzer 73 analyzes the frequency of the digitized reflected wave signal by FFT or the like, or measures the period of the digitized reflected wave signal, thereby obtaining the heat on the surface of the rolling roll 110. The frequency of the reflected signal from the mechanical and mechanical damage is measured, and the measured value serves to measure the depth of the thermal and mechanical damage on the surface of the rolling roll 110. The frequency analyzer 73 can be realized by, for example, a computer that operates according to frequency analysis software and period measurement software.

The measured value of the depth of the thermal and mechanical damage on the surface of the rolling roll 110 measured by the frequency analyzer 73 is transmitted to the controller 80 of the grinding machine, and thereafter, according to the measured value, 110 grinding is performed.

Since the ultrasonic measuring apparatus of the present embodiment has the above-described apparatus configuration, water serving as an ultrasonic wave propagation medium is supplied between the surface acoustic wave probe 10 and the surface of the rolling roll 110 as an object. While supplying, the probe 10 scans and moves on the surface,
Work to analyze the frequency of the reflected signal from the mechanically damaged portion and measure the depth of the thermally and mechanically damaged portion, the roll 11
The operation of detecting a surface defect by catching a reflection signal from a surface defect of 0 can be performed easily and reliably. Further, the operation of grinding the surface of the rolling roll 110 can be easily and reliably performed based on the measured depth of the thermally and mechanically damaged portion.

Next, the surface acoustic wave probe 10 applied to this embodiment will be described in detail with reference to FIG.

As shown in FIG. 6, the surface acoustic wave probe 10 provided in the ultrasonic flaw detector of this embodiment mainly includes an ultrasonic vibrator 10A, a damping material 10B, and a resin wedge 1B.
With the configuration from 0C, when the center frequency of the surface wave to be transmitted and received is fc, the frequency bandwidth of the surface wave probe is 0.50 fc or more.

That is, assuming that the frequency spectrum of the surface wave transmitted and received by the surface wave probe 10 has a frequency distribution conceptually shown in FIG. 7, the peak value of the spectrum intensity (signal intensity) is- A frequency width within a range of 6 dB: fR-fL is defined as a frequency bandwidth, and the following equation (1) is satisfied.

FR−fL ≧ 0.50fc (1)

As described above, in this embodiment, the frequency bandwidth of the surface acoustic wave probe 10 is limited to 0.50 fc or more.

The specific configuration of the surface acoustic wave probe 10 will be described. The ultrasonic vibrator 10A includes a lead niobate ceramic, a 1-3 composite vibrator, a 0-3 composite vibrator, and a 3-1 composite vibrator. For example, a vibrator having a low mechanical Q value, such as a ceramic having a high mechanical Q value, or a vibrator which is easily mechanically damped, such as lead titanate-based porcelain, can be used. Here, the mechanical Q value is an amount representing the sharpness of resonance vibration, and the longer the Q value, the longer the duration of vibration.

As the damping material 10B, an object obtained by mixing a powder having a large specific gravity, such as tungsten (metal), with an epoxy resin or the like and solidifying it is used as the ultrasonic vibrator 10A.
The ultrasonic vibration generated in the ultrasonic vibrator 10A is damped by being attached to the back surface of the ultrasonic vibrator 10A. Here, the volume fraction of the tungsten powder in the damping material 10B is 4
0% or more was adequate.

Ultrasonic vibrator 10A, damping material 10B
With the above material configuration, an ultrasonic pulse having a frequency bandwidth of 0.50 fc or more can be generated (transmitted).

The resin wedge 10C is arranged so that the ultrasonic vibration satisfies the following expression (2) and the normal to the bottom surface of the wedge 10C that comes into contact with the surface of the subject via the medium so as to be incident on the subject. S
1 has an inclined surface where a normal S2 intersects at an incident angle θi, and the front surface (surface for transmitting and receiving ultrasonic waves) of the ultrasonic transducer 10A is attached to the inclined surface. And this wedge 10C is, for example, a polystyrene resin,
It is formed using a polyimide resin, an acrylic resin, a fluororesin, or the like.

Θi = sin ⁻¹ (CW / CR) (2) where CW: velocity of ultrasonic wave in resin wedge CR: velocity of surface wave on roll

Next, the ultrasonic vibrator 10 shown in FIG.
A, a damping material 10B, and a resin wedge 10C were provided with a lead niobate-based porcelain, a damping material obtained by mixing tungsten powder with an epoxy resin at a volume fraction of 60%, and a surface wave probe 10 formed of a polyimide resin. Using the apparatus of the present embodiment, the depth of the thermally / mechanically damaged portion is measured for 500 work rolls for hot finishing rolling, and the thermal / mechanical when grinding is performed based on the measurement. The frequency of occurrence of uncut material in the damaged area was investigated, but no uncut material was found. As a comparative example, when the same investigation was performed on the case where grinding was performed based on the height of the reflected wave from the thermally and mechanically damaged portion, about 10 rolls were left uncut.

As described in detail above, according to the present embodiment,
The amount of grinding can be optimized according to the depth of the thermally and mechanically damaged portion, and it is possible to prevent uncut portions of the thermally and mechanically damaged portion.

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

For example, the specific materials of the ultrasonic vibrator 10A, the damping material 10B, and the resin wedge 10C, which are members constituting the surface acoustic wave probe, are not limited to those shown in the above embodiment, but have the same functions. Any material can be used as long as it has.

In the embodiment, the case where water is used as the couplant has been described, but other liquid substances such as oil may be used.

[0048]

As described above, according to the present invention,
It is possible to accurately measure the depth of a thermally and mechanically damaged portion of a rolling roll that has been thermally and mechanically damaged by rolling, and thereby always optimize the roll grinding amount.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the relationship between the frequency of a reflected wave of a surface wave and the depth of a thermally and mechanically damaged portion for explaining the principle of the present invention.

FIG. 2 is a graph showing a relationship between a required grinding amount and a frequency of a reflected wave from a thermally / mechanically damaged portion.

FIG. 3 is a side view showing a schematic configuration of an ultrasonic flaw detector according to an embodiment of the present invention.

FIG. 4 is an enlarged front view showing a probe holder part of the ultrasonic flaw detector.

FIG. 5 is a fragmentary side view showing a water supply unit provided in the surface acoustic wave probe of the ultrasonic flaw detector.

FIG. 6 is an enlarged sectional view schematically showing the surface acoustic wave probe.

FIG. 7 is a diagram for explaining a frequency bandwidth of the surface acoustic wave probe.

FIG. 8 is a conceptual diagram for explaining cracks generated on a circumferential surface of a rolling roll.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Surface wave probe 12 ... Probe holder 16 ... Guide 18 ... Holding mechanism part 20 ... Roller 22 ... Copying roller 28 ... Conduit 30 ... Scraper 70 ... Ultrasonic flaw detector 71 ... A / D converter 72 ... Level judging device 73 ... Frequency analyzer 80: Grinding device 110: Rolling roll

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yasuo Yarida 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Inside the Technical Research Institute of Kawasaki Steel Corporation (72) Ryoichi Sugimoto 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki F term in Chiba Works (Reference) 2F068 AA24 AA48 BB12 CC04 FF12 FF16 GG01 HH03 JJ23 KK12 NN02 QQ10 QQ45 2G047 AA07 AB01 BC03 BC04 BC10 BC18 CB03 GE03 GF11 GG09 GG33 4E016 AA08 CA08

Claims (4)

[Claims] 1. A surface wave probe is brought into contact with a surface of a rolling roll via a couplant film while rotating a rolling roll having its surface thermally and mechanically damaged by rolling. While transmitting the surface wave, it receives the reflected wave from the thermally or mechanically damaged portion existing or remaining on the surface of the rolling roll, extracts only the reflected wave having an amplitude larger than a predetermined threshold, and changes the frequency. And measuring the depth of the thermally and mechanically damaged portion based on the measured value. 2. The frequency bandwidth of the surface wave probe (where the intensity is within -6 dB relative to the peak in the frequency spectrum), where fc is the center frequency of the surface wave transmitted and received by the surface wave probe. (Width of range) is set to 0.50 fc or more. 3. The grinding of a roll having a surface thermally and mechanically damaged by rolling, while rotating the roll before starting the grinding or during the grinding, the surface of the roll is rotated. A surface wave probe is brought into contact with the couplant film, a surface wave is propagated from the surface wave probe, and a reflected wave from a thermally or mechanically damaged portion existing or remaining on the surface of the rolling roll is received, Only the reflected wave whose amplitude is larger than a predetermined threshold is extracted and its frequency is measured. Based on this, the depth of the thermally / mechanically damaged portion is measured, and the measured thermal / mechanical A grinding method for a rolling roll, characterized in that a subsequent grinding amount is set according to the depth of a damaged portion and grinding is performed. 4. The frequency band of the surface wave probe (in the frequency spectrum, the intensity is within -6 dB with respect to the peak, assuming that the center frequency of the surface wave transmitted and received by the surface wave probe is fc). A width of the range) of 0.50 fc or more.