Roll diameter distribution derivation device and derivation method

Abstract

To provide a technique capable of deriving the roll diameter distribution of a rolling roll over the whole circumference and the whole width of the rolling roll.SOLUTION: A device for deriving a roll diameter distribution of a barrel portion of a hot rolling roll, the device comprising: a displacement measurement mechanism that measures surface displacement information including a distance from a detection unit facing a surface of the rolling roll to the surface of the rolling roll as information; A reciprocating mechanism capable of reciprocating in a direction parallel to an axis of the rolling mill roll and capable of detecting a movement amount, a rotation mechanism capable of relatively moving the displacement measurement mechanism in a circumferential direction along a surface of the rolling mill roll, a rotation detection mechanism capable of detecting roll rotation information including a rotation speed by the rotation mechanism and position information of the detection unit in the circumferential direction of the rolling mill roll, and a calculation device that calculates an axial roll diameter distribution of a body portion of the rolling mill roll from the measured surface displacement information and the measured roll rotation information.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an apparatus for deriving roll diameter distribution of a hot rolling roll barrel resulting from wear on the roll surface of a rolling roll such as a hot rolling roll, and a method for deriving roll diameter distribution of a hot rolling roll barrel. [Background technology]

[0002] As a conventional technique for measuring the roll diameter distribution of a hot rolling roll barrel, for example, Patent Document 1 discloses a roll profile measuring device. In this device, a distance meter is moved parallel to the roll axis to measure the distance from the distance meter to the roll surface, and the obtained measurement value is calculated to calculate the roll diameter distribution in the width direction of the hot rolling roll barrel, which is the object to be measured.

[0003] Furthermore, Patent Document 2 discloses a technique for measuring roll profiles. In this technique, a roll to be measured is set in place, and a non-contact displacement sensor is attached to a carriage that is movable freely parallel to the roll axis. This makes it possible to measure the roll diameter distribution of the barrel of a hot rolling roll more accurately without requiring a large-scale setup, by detecting the travel time from a reference position of the non-contact displacement sensor and the carriage that moves at a constant speed.

[0004] Patent Document 3 discloses a surface profile measuring device. The device is equipped with three range finders, and accurately measures the roll diameter distribution of a hot rolling roll barrel by eliminating pitching motion and translational error during movement. This prevents translational errors caused by the range finders or the object being measured moving closer to or farther from each other due to vibrations caused by the movement of the range finders or the object being measured, and prevents pitching errors caused by changes in inclination, improving measurement accuracy.

[0005] Furthermore, Patent Document 4 discloses a surface defect detection technology for mill rolls as a technology for inspecting and determining minute defects on the outermost surface layer of a roll. This technology involves a device that includes a rotation mechanism that rotates the mill roll around its axis, a displacement sensor with a detection unit facing the surface of the mill roll and measuring the distance from the detection unit to the surface of the mill roll, and a reciprocating table that supports the displacement sensor and is movable back and forth in a direction parallel to the width direction of the mill roll. This device is capable of measuring the surface condition of the entire circumference and width of the roll, and is capable of inspecting for localized, three-dimensional chipping on the roll, measuring a few millimeters in size.

[0006] Patent Document 5 discloses a roll profile measurement method. This technique involves measuring the distance to the surface of the roll to be measured at short time intervals Δt using a displacement meter while rotating the roll and moving the displacement meter relatively in parallel with the axis of the roll to be measured, and calculating the obtained distance measurements to determine the roll diameter distribution of the rotating roll to be measured. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Utility Model Application Publication No. 07-03955 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-156325 [Patent Document 3] Japanese Patent Application Publication No. 11-142137 [Patent Document 4] Japanese Patent Publication No. 2023-053825 [Patent Document 5] Japanese Patent Application Publication No. 11-125519 Summary of the Invention [Problem to be solved by the invention]

[0008] Hot rolling rolls are in direct and prolonged contact with steel products. Therefore, if a roll defect occurs or if there is an abnormality in the roll diameter distribution of the hot rolling roll barrel, it can have a significant impact, such as a deterioration in the quality of the steel products or the need to stop operations due to recovery measures.

[0009] The conventional techniques described in Patent Documents 1 to 5 have the following problems. There is a method for accurately measuring the roll diameter distribution of a hot rolling roll barrel in the width direction of the roll by eliminating translation errors due to deviations in the speed of the measuring device. There is also a method for measuring the profile of a rotating roll without being affected by roll eccentricity by separately detecting the roll rotation speed and eliminating the frequency component corresponding to this rotation speed from the distance measurement value. On the other hand, there is no method for continuously measuring the roll diameter distribution of a hot rolling roll barrel over the entire width of the roll while the roll is rotating. Therefore, there is a problem in that it is not possible to inspect or discover the roll diameter distribution over the entire circumference and width of the roll, including information on localized uneven wear, etc. Another problem with measuring a rotating roll is that roll diameter distribution plots can only be obtained for the number of rotations per unit measurement width relative to the roll width direction.

[0010] The present invention has been made in view of the above circumstances, and has an object to provide a technique for deriving the roll diameter distribution of a hot rolling roll barrel over the entire circumference and width of the roll, which enables continuous measurement in the circumferential direction and is more reliable. [Means for solving the problem]

[0011] The gist of the present invention, which advantageously solves the above problems, is as follows. [1] A device for deriving a roll diameter distribution of a barrel portion of a hot rolling roll, comprising: a displacement measuring mechanism for measuring surface displacement information having information on the distance from a detection unit facing the surface of the rolling roll to the surface of the rolling roll; a reciprocating movement mechanism for supporting the displacement measuring mechanism and capable of reciprocating in a direction parallel to the axis of the rolling roll and capable of detecting the amount of movement; a rotation mechanism for relatively moving the displacement measuring mechanism in a circumferential direction along the surface of the rolling roll; a rotation detection mechanism for detecting roll rotation information including the number of rotations by the rotation mechanism and position information of the detection unit in the circumferential direction of the rolling roll; and a calculation device for calculating the axial roll diameter distribution of the barrel portion of the rolling roll from the measured surface displacement information and the measured roll rotation information. [2] In the above [1], the calculation device is a roll diameter distribution deriving device having a first calculation unit that calculates the surface displacement information measured by the displacement measurement mechanism into roll diameter information for each rotation of the rolling roll, and a second calculation unit that evaluates the degree of wear of the part of the barrel of the rolling roll that is used to roll steel products, using the value of the part that is not used to roll steel products, as a reference value for the representative value of the roll diameter information for each rotation obtained. [3] In the above [2], the representative value of the roll diameter information is at least one of an average value in the circumferential direction and a difference between a maximum value and a minimum value, and the degree of wear to be evaluated is information on local unevenness of wear. [4] In any one of the above [1] to [3], the detection unit is a roll diameter distribution deriving device capable of measuring distances between a plurality of measurement points within a measurement range of a predetermined length in a direction parallel to the axis of the rolling roll. [5] A roll diameter distribution deriving method, comprising: using the roll diameter distribution deriving device according to any one of [1] to [4] above; relatively rotating a displacement measuring mechanism in the circumferential direction of the rolling roll; relatively moving the reciprocating mechanism in a direction parallel to the axis of the rolling roll while bringing a detection unit of the displacement measuring mechanism closely facing the surface of the rolling roll; acquiring surface displacement information over the entire circumferential length of the barrel of the rolling roll; and simultaneously acquiring roll rotation information from a rotation detection mechanism; and calculating the axial roll diameter distribution of the barrel of the rolling roll from the surface displacement information and the roll rotation information. [Effects of the Invention]

[0012] According to the present invention, the roll diameter distribution of a hot rolling roll barrel can be calculated from the results of measuring the distance between the surface of a roll to be measured and a displacement sensor while the roll is rotating. This makes it possible to obtain wear information not only in the width direction but also in the circumferential direction. Furthermore, since a plot of the roll diameter distribution can be obtained up to the minimum resolution of the displacement measurement mechanism of the present invention, the number of plots is much greater than in the past, making it possible to obtain a roll diameter distribution per width direction with higher accuracy. Measurement by rotating the roll can eliminate eccentricity, and even with a mechanism such as a roll grinding carriage that has low rigidity and is prone to roll runout, an apparatus having a mechanism such as the present invention can perform stable measurements without being affected by eccentricity.

[0013] Based on more reliable information on the roll diameter distribution of the hot rolling roll barrel, it has become possible to take measures such as focusing on grinding the relevant areas to address quality risks and the risk of operation shutdowns. In addition, optimizing the amount of roll grinding has the effect of improving the roll consumption rate. [Brief explanation of the drawings]

[0014] [Figure 1] 1A and 1B are schematic diagrams showing an overview of a roll diameter distribution deriving device according to one embodiment of the present invention, in which (a) is a schematic side view and (b) is a schematic plan view. [Figure 2]FIG. 4 is a flowchart showing an example of a calculation process of the roll diameter distribution deriving device according to the embodiment. [Figure 3] FIG. 2 is a schematic diagram illustrating an outline of a process of a roll diameter distribution deriving method using the roll diameter distribution deriving device according to the embodiment. [Figure 4] FIG. 2 is a schematic diagram showing an example of a display of a roll diameter distribution in the width direction of a rolling roll calculated by the roll diameter distribution deriving device according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described in detail. Note that the drawings are schematic and may differ from the actual ones. Furthermore, the following embodiments exemplify equipment and methods for embodying the technical idea of ​​the present invention, and are not intended to limit the configuration to those described below. In other words, the technical idea of ​​the present invention can be modified in various ways within the technical scope described in the claims.

[0016] FIG. 1 is a schematic diagram showing an overview of a roll diameter distribution calculation device according to one embodiment of the present invention. FIG. 1(a) is a schematic side view, and FIG. 1(b) is a schematic plan view. The roll diameter distribution calculation device of this embodiment includes a rotation mechanism, a reciprocating mechanism, a displacement sensor 2 as a displacement measurement mechanism, a rotation sensor 15 as a rotation detection mechanism, and a calculation device 5 that calculates the roll diameter distribution. The calculation device 5 may further include laser distance meters 19A and 19B and a control unit 10. As shown in FIG. 2, the calculation device 5 includes a one-rotation position recording unit 5A, a calculation unit 5B for a roll diameter representative value for one rotation of the roll, a calculation unit 5C for the width direction roll diameter distribution of the roll barrel, a counting unit 5D, a visualization processing unit 5E, and a display unit 5F.

[0017] <Rotation mechanism> The rotation mechanism may take any form as long as the displacement sensor 2 can move circumferentially along the surface of the roll 1. In the example shown in FIG. 1(b), the mechanism rotates the roll 1 axially. The roll 1 is attached to a chock 12 (bearing) and installed in the roll diameter distribution calculation device. One shaft of the roll 1 is connected to a tailstock 13, and the other shaft is connected to a headstock 14. A motor 14A, such as a single-shaft servo motor, is mounted on the headstock 14 to drive the other shaft. Driving the motor 14A enables the roll 1 to rotate axially. A rotation sensor 15 is provided to detect the rotation speed and rotation angle of the motor 14A. In the example shown in FIG. 1, the rotation mechanism is described as rotating the roll 1 axially, but the mechanism may also rotate the displacement sensor 2 around the stationary roll 1.

[0018] <Reciprocating mechanism> The reciprocating mechanism may take any form as long as the carriage 4 supporting the displacement sensor 2 can reciprocate along the surface of the roll 1 in a direction parallel to the axis of the roll 1. In the example of Figures 1(a) and (b), the carriage 4 is disposed to the side of the roll 1. The carriage 4 is movable in a reciprocating direction, which is a direction parallel to the axis of the roll 1. The reason for specifying the direction as parallel to the axis is to indicate that it does not have to be completely parallel to the axis. In the example of Figure 1, the carriage 4 moves, but it is also possible to configure the roll 1 to reciprocate in the axial direction with the displacement sensor 2 fixed.

[0019] <Rotation sensor 15> The rotation sensor 15 may be any sensor capable of recording the rotation speed of the rotation mechanism of the rolling roll 1 being measured and the position information of the displacement sensor 2 in the circumferential direction of the rolling roll 1, for example, the position information for one rotation along the roll surface. In the example shown in FIG. 1(b), the rotation sensor 15 detects the rotation speed and rotation angle of the motor 14A. It may also be capable of calculating the timing of one rotation from the roll rotation speed and period, or measuring the rotation speed and rotation timing using pulse signals or contact / non-contact sensors. The measurement accuracy of the rotation position depends on the roll diameter, i.e., the circumferential length, but can be balanced with the measurement time. For example, the measurement interval for the circumferential displacement is preferably 0.5° or less, more preferably 0.2° or less. It is preferably 0.01° or more, and even more preferably 0.05° or more.

[0020] <Displacement sensor 2> The displacement sensor 2 is supported by the carriage 4 and is positioned so that its detection part faces (opposes) the rolling roll 1. The displacement sensor 2 measures the distance to the roll surface of the rolling roll 1. Any known displacement sensor may be used for the displacement sensor 2. Since the displacement sensor 2 only needs to be able to measure the distance between the rolling roll 1 and the displacement sensor 2, it may be of either a non-contact or contact type as long as it can determine the distance. An advancing / retracting mechanism 3 is provided which moves the displacement sensor 2 toward and away from the carriage 4 towards the roll surface. The advancing / retracting mechanism 3 is made up of a linear guide device or other servo mechanism.

[0021] The displacement sensor 2 is preferably a two-dimensional distance sensor. This is particularly preferred because it can simultaneously measure the distance from the displacement sensor 2 to the surface of the opposing roll 1 for multiple measurement points within a measurement range of a predetermined length parallel to the roll axis. Therefore, the roll diameter distribution over the entire circumference of the surface of the roll 1 can be measured accurately and in a short time. The length over which the displacement sensor 2 can measure distances in the direction parallel to the roll axis is preferably approximately 20 to 240 mm. Furthermore, it is preferable that the displacement sensor 2 can simultaneously measure 64 to 512 measurement points within the measurement range. Within this range, the measurement interval accuracy in the axial direction can be approximately 0.1 to 0.3 mm, and measurement can be performed efficiently and with high precision without excessive measurement time or data processing time.

[0022] <Laser rangefinder 19A, 19B> Laser distance meters 19A and 19B are preferably installed on both the left and right sides of the carriage 4 in the direction of travel of the displacement sensor 2. With only the displacement sensor 2, there is a risk that the advancing displacement measurement mechanism may interfere with parts of the roll shaft other than the roll barrel, or that non-target areas, such as the C-chamfered portions at the widthwise ends of the roll barrel, may be detected as roll defects. Therefore, to solve these problems, the laser distance meters 19A and 19B, which have a longer measurable distance than the displacement sensor 2, are utilized. Specifically, the laser distance meters 19A and 19B are installed upstream and downstream of the displacement sensor 2's installation position in the reciprocating direction. It is sufficient to have at least the upstream laser distance meter 19A. The laser distance meters 19A and 19B constitute distance detection sensors and detect the distance to the surface of the roll shaft and barrel. Here, the displacement sensor 2 and the laser distance meters 19A and 19B are both installed on the carriage 4 and move together in the reciprocating direction. The difference in distance values ​​in the roll width direction is calculated from the measurement results of the laser rangefinders 19A and 19B, which are the distances between the rangefinders and the object being measured. Measurements by the displacement sensor 2 are not performed at the roll shaft. Instead, when the roll approaches a C-chamfered portion or the like formed at the widthwise end of the roll barrel, the advancing / retracting mechanism 3 is advanced to initiate measurement by the displacement sensor 2. If the difference in distance values ​​exceeds the threshold for a set number of consecutive points, the measurement data from that point onward is calculated as belonging to the roll barrel (measurement range). Conversely, when the roll reaches the C-chamfer at the other end of the roll barrel width direction, the difference in distance values ​​beyond the threshold is not used as measurement data, and the advancing / retracting mechanism 3 retracts the displacement sensor 2. A device other than a laser rangefinder can be used that can determine the distance between the rangefinder and the object being measured. It is preferable that the measurement resolution of the displacement sensor 2 be superior to that of the laser rangefinders 19A and 19B.

[0023] <Control unit 10> The control unit 10 includes an advance / retract control unit. The advance / retract control unit performs processing to advance / retract the displacement sensor 2 toward / from the roll surface via the advance / retract mechanism 3 according to the distance detected by the laser range finders 19A and 19B. For example, when the advance / retract control unit determines that the displacement sensor 2 is positioned facing the roll surface based on the detection values ​​of the laser range finders 19A and 19B, it moves the displacement sensor 2 closer to the roll surface while avoiding interference between the displacement sensor 2 and the roll surface. This approach improves the accuracy of the measurement value. Here, by inputting information such as the roll diameter and roll barrel length of the mill roll 1 into the control unit 10 in advance, the displacement sensor 2 approaches the roll surface to an appropriate distance standard.

[0024] At this time, the rolling roll 1 is attached with a chock 12, and depending on the combination of the roll diameter and the chock 12, there is a possibility that the displacement sensor 2 may interfere with the chock 12. For example, as shown in FIG. 1(b), there are cases in which the chock 12 protrudes further toward the shuttle 4 than the diameter of the rolling roll 1. In this case, if the displacement sensor 2 is brought close to the preset appropriate distance standard for the rolling roll 1, the displacement sensor 2 will interfere with the chock 12.

[0025] In response to this, the advance / retract control unit is able to detect the roll barrel end of the rolling roll 1 based on the distance detected by at least the laser range finder 19A located upstream of the displacement sensor 2, and moves the displacement sensor 2 backward until it reaches the roll barrel end position. Then, when it determines that the displacement sensor 2 has reached the roll barrel end, it performs approach / retract control to move the displacement sensor 2 closer to the roll surface. Here, during inspection, the carriage 4 moves in one of the advance / retract directions at a constant moving speed corresponding to the roll rotation speed (constant speed) based on detection by the rotation detector. Furthermore, even when the displacement sensor 2 is approaching the roll surface and measuring the distance to the roll surface, the detection information from the laser range finders 19A and 19B makes it possible to more reliably avoid interference of the displacement sensor 2 with the roll surface.

[0026] <Measurement of the distance between the displacement sensor and the rolling roll surface> In the above configuration, the roll surface of the rolling roll 1 is measured spirally by continuously measuring with the displacement sensor 2 while the rolling roll 1 rotates at a constant number of revolutions and the carriage 4 operates at a constant speed. In reality, scanning is performed in a direction slightly tilted relative to the direction of roll rotation. The displacement data (distance data) measured by the displacement sensor 2 becomes the surface displacement information. When a two-dimensional displacement sensor is used for the displacement sensor 2, the moving distance of the displacement sensor 2 in the tooth lateral movement parallel to the roll axis per rotation of the rolling roll is measured as the distance of the displacement sensor 2.

[0027] <Calculation section 5> When a two-dimensional displacement sensor is used, the measurement information from the displacement sensor 2 is a sequence composed of rows and columns. In this embodiment, the roll is rotated while moving axially to continuously measure the inter-roll distance in a spiral pattern. Therefore, the sequence is composed of the number of columns corresponding to the sensor measurement width and the number of rows corresponding to the total length of the continuously measured spiral. For example, for a roll diameter of 700 mm, the roll circumferential direction is measured every 0.1° over a 360° circumference. The 50 mm measurement range of the displacement sensor in the roll axial direction is divided into 257 pixels, and measurements are performed with an accuracy of approximately 0.2 mm per pixel, and the displacement data is stored. This sequence is used to calculate the roll diameter distribution in the width direction of the barrel of the rolling roll 1 according to the flow shown in Figure 2. In the flow illustrated in Figure 2, the surface displacement information, consisting of a sequence in which the measurement width of the displacement sensor 2 is the number of columns and the total length of the continuously measured spiral is the number of rows, is divided into rows for each rotation based on roll rotation information recording the position of one rotation of the roll, and the rows are joined together in the roll width direction. For example, a two-dimensional map consisting of the circumferential direction θ and the total roll width W is constructed as shown in Fig. 3. In the example of Fig. 3, the average value of the average calculation points 7 for each revolution is calculated as a representative value of the roll diameter for each range finder field of view 6. Then, the representative values ​​are tallied by the tallying unit 5D, visualized by the visualization processing unit 5E, and displayed on the display unit 5F as shown in Fig. 4.

[0028] The one-rotation position recording unit 5A records the position of the rolling roll 1 for each rotation during measurement, for example, the row number in the above number sequence, as roll rotation information. Based on this roll rotation information, the surface displacement information measured by the displacement sensor 2 is divided into rotation numbers.

[0029] The roll diameter representative value calculation unit 5B constitutes a first calculation unit that calculates the average value for each measurement circumference from the divided surface displacement information, for example, Ave1 to AveN in FIG. 3. Here, the representative value to be calculated may be the average value for each unit width ws, or the maximum or minimum value for each unit width ws. The calculation may use the entire unit width ws or a specific portion within the unit width ws. It may also be a value representing multiple circumferences rather than one circumference, or multiple points within the unit width ws. The roll rotation speed may be increased during measurement to shorten the unit width ws, allowing for a more precise roll diameter distribution to be calculated.

[0030] The width direction roll diameter distribution calculation unit 5C, as a second calculation unit, sets the average of one or more revolutions of the portion at the width direction end of the barrel of the rolling roll 1 that is not used for rolling the steel product as a reference value 8. Then, the width direction roll diameter distribution of the barrel of the rolling roll 1 is calculated by calculating the deviation 9 between the reference value 8 and the average for each unit width of the other portions.

[0031] The method of this embodiment is most effective when applied to the entire circumference of the roll, 0 to 360°. However, if the state of the roll can be determined by measuring only half the circumference, 0 to 180°, or by calculating the roll diameter distribution, this embodiment may be applied without measuring the entire circumference. [Example]

[0032] A roll to be inspected, 1780 mm wide and 781 mm in diameter, was placed on the roll table shown in Figure 1(b), and the roll was rotated at a speed of 10 revolutions per minute. In this state, the grinding table on which the displacement sensor was installed was moved back and forth in a direction parallel to the roll axis at a speed of 600 mm / min, and the distance between the roll and the displacement sensor was measured by a laser rangefinder at a distance of 120 mm.

[0033] Measurements were carried out while detecting the rotational position per roll rotation using a limit sensor installed on the roll table. Measurements were taken in 0.1° increments for the 360° circumference of the roll, and the displacement sensor's measurement range of 50 mm in the roll axis direction was divided into 257 pixels, with measurements taken with an accuracy of about 0.2 mm per pixel, and the displacement data was stored.

[0034] From the measurement results, the average value was calculated within a range of 50 mm from the end of the roll barrel and over the entire circumference of the roll, and this was used as a reference value. The deviation from the average value of the surface displacement outside this portion was calculated, and the roll diameter distribution of the hot rolling roll barrel was calculated according to the flow shown in Figure 2.

[0035] Through the calculation processing flow of Fig. 2, it was possible to display the roll diameter distribution of the hot rolling roll barrel as shown in Fig. 4. Fig. 4 shows a display area 20 for the distance data of the entire circumference and width, and a display area 21 for the roll diameter distribution in the width direction of the hot rolling roll barrel.

[0036] While existing technologies and measurement methods could only measure and evaluate specific circumferential and widthwise positions on the roll, it has become possible to measure the roll diameter distribution on the entire circumference and width of the hot rolling roll barrel. This has made it easier to determine defective parts of the roll and the completion of grinding during normal grinding, and it has been found to be effective in optimizing the amount of roll grinding that was excessive, reducing the amount of roll grinding while improving product quality and suppressing the risk of operation shutdowns. [Explanation of symbols]

[0037] 1. Rolling mill 2. Displacement sensor (displacement measurement mechanism) 3 Advancement / retraction mechanism 4 Reciprocating table (reciprocating mechanism) 5 (Roll diameter distribution) calculation unit 5A 1 rotation position recording unit 5B Calculation section for representative roll diameter (per roll rotation) 5C (roll barrel width direction) roll diameter distribution calculation section 5D tallying section 5E Visualization processing section 5F display section 6 (1 lap) Rangefinder field of view (unit width) 7 (1 lap) average calculation points 8 Reference value (average of one or more revolutions of the roll at the end of the roll) 9 Deviation (from the average of each unit range to the reference value) 10 Control Unit 12 Chock 13 Tailstock 14 Headstock 14A motor (rotating mechanism) 15 Rotation Sensor 19A, 19B Laser rangefinder (distance detection sensor) 20 Distance data display area 21. Display area for roll diameter distribution (of hot rolling roll barrel)

Claims

1. An apparatus for deriving a roll diameter distribution of a barrel portion of a hot rolling roll, comprising: a displacement measuring mechanism that measures surface displacement information having information indicating the distance from a detection unit facing the surface of the rolling roll to the surface of the rolling roll; a reciprocating mechanism that supports the displacement measuring mechanism, is reciprocating in a direction parallel to the axis of the rolling roll, and is capable of detecting the amount of movement; a rotation mechanism that allows the displacement measuring mechanism to move in a circumferential direction along the surface of the rolling roll; a rotation detection mechanism capable of detecting roll rotation information including the number of rotations by the rotation mechanism and position information of the detection unit in the circumferential direction of the rolling roll; a calculation device that calculates the axial roll diameter distribution of the barrel portion of the rolling roll from the measured surface displacement information and the measured roll rotation information.

2. The computing device a first calculation unit that calculates the surface displacement information measured by the displacement measuring mechanism into roll diameter information for each rotation of the rolling roll; and a second calculation unit that evaluates the degree of wear of a portion of the barrel of the rolling roll that is used to roll the steel product, using the value of the portion of the barrel of the rolling roll that is not used to roll the steel product as a reference for the representative value of the roll diameter information obtained for each rotation.

3. the representative value of the roll diameter information is at least one of an average value in a circumferential direction and a difference between a maximum value and a minimum value, The roll diameter distribution deriving device according to claim 2 , wherein the degree of wear to be evaluated is information on unevenness of local wear.

4. 2. The roll diameter distribution deriving device according to claim 1, wherein the detection unit is capable of measuring distances to a plurality of measurement points within a measurement range of a predetermined length in a direction parallel to the axis of the reduction roll.

5. Using the roll diameter distribution deriving device according to any one of claims 1 to 4, a displacement measuring mechanism is rotated relatively in the circumferential direction of the rolling roll, and while a detection unit of the displacement measuring mechanism is positioned close to and facing the surface of the rolling roll, the reciprocating mechanism is moved relatively in a direction parallel to the axis of the rolling roll, Acquire surface displacement information over the entire circumference of the barrel portion of the rolling roll, At the same time, roll rotation information is acquired from the rotation detection mechanism, A roll diameter distribution deriving method for calculating an axial roll diameter distribution of the barrel portion of the rolling roll from the surface displacement information and the roll rotation information.

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