Three-dimensional surface roughness evaluation method and three-dimensional surface roughness evaluation device

Abstract

To provide a three-dimensional surface roughness evaluating method and a three-dimensional surface roughness evaluating device which can quickly, consecutively, extensively and directly acquire a surface roughness parameter about three-dimensional surface roughness of an object, a structure and the like that cannot be transported.SOLUTION: A three-dimensional surface roughness evaluating method comprises the steps of: specifying an effective measurement width range of a two-dimensional laser displacement meter by measuring a surface roughness parameter of a measurement object 22 while changing the measurement width of the two-dimensional laser displacement meter 12; acquiring displacement data by measuring the displacement for each fixed interval in the X-axis direction with the measurement width within the specified effective measurement width range by the two-dimensional laser displacement meter; generating reference surface data of each coordinate by averaging in the Y-axis direction the displacement data with the measurement width within the specified effective measurement width range; and generating three-dimensional surface roughness data of the measurement object by subtracting the reference surface data of each coordinate from the displacement data of each X-Y plane coordinate.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a three-dimensional surface roughness evaluation method and a three-dimensional surface roughness evaluation device for acquiring surface roughness parameters relating to the three-dimensional surface roughness of an untransportable object, structure, etc. Specifically, the present invention relates to a three-dimensional surface roughness evaluation method and a three-dimensional surface roughness evaluation device that can acquire surface roughness parameters quickly, continuously, in large quantities, and directly. [Background technology]

[0002] The surface roughness profile of an object is important in understanding the friction characteristics of that surface. In recent years, as shown in Non-Patent Document 1, the importance of measuring not only the roughness height but also shape parameters including wavelength, etc., has been shown to be important in understanding the water flow friction characteristics of an object surface.

[0003] Non-patent document 1 describes the evaluation of the surface roughness (paint surface roughness) of a ship hull, and indicates that in order to evaluate the surface roughness of non-transportable objects or structures such as a ship hull, it is necessary to measure a sufficient number of shape parameters over an extremely wide area.

[0004] In addition, it has been pointed out that when using a conventional roughness measuring device, the "BSRA HULL ROUGHNESS ANALIZER," precise measurement of the hull surface roughness and parameter analysis are not possible. In order to solve this problem, Non-Patent Document 1 creates a roughness replica of the hull surface using thermoplastic resin, and measures the surface roughness of the hull by performing surface analysis of the roughness replica in a laboratory using a point-like laser displacement meter mounted on an XY stage.

[0005] Patent Document 1 proposes a non-contact roughness measuring device for measuring the roughness of unportable objects and structures, etc., using a shadow image recording device. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 61-292509 [Non-patent literature]

[0007] [Non-Patent Document 1] Hiroo Mieno, Hiroshi Masuda, "Increased Resistance Due to Surface Roughness of Ship Bottom Paint - Reduction of Ship Hull Resistance by Painting on Ship Bottom Shell Plates", Journal of the Japan Society of Marine Engineering, Vol. 48, No. 3 (2013), p300-307 Summary of the Invention [Problem to be solved by the invention]

[0008] The method disclosed in Non-Patent Document 1 has a problem that the area that can be replicated by roughness replica is limited, and therefore excessive effort is required to evaluate a large area. In addition, the method disclosed in Patent Document 1 measures roughness based on a shadow image captured by irradiating a light source, so it is not suitable for accurately measuring the shape parameters of a relatively smooth surface.

[0009] Furthermore, when measuring the roughness parameters of minute roughness on the order of micrometers, the most accurate measurements can be achieved by traversing a laser-type optical displacement gauge on an XY stage or the like to ensure mechanical precision.

[0010] However, when such a method is used to measure a wide area such as a ship's hull, the size of the traverse device increases, and the weight of the traverse device increases, making it difficult to handle at the site for processing, painting, etc. Even if the size is increased, there are technical constraints that limit the operating range and measurement range of the traverse device.

[0011] Furthermore, when using an XY stage, it is necessary to use a precision stage and a stepping motor to perform precise movements in the XY directions. It is also necessary to have an XY stage controller to control such an XY stage, and a controller for the laser displacement meter. This makes the measuring device heavy and consumes a lot of power, making it unsuitable for carrying around.

[0012] In view of the current situation, the present invention aims to provide a three-dimensional surface roughness evaluation method and a three-dimensional surface roughness evaluation device that can quickly, continuously, directly and in large quantities obtain surface roughness parameters relating to the three-dimensional surface roughness of objects, structures and the like that cannot be transported. [Means for solving the problem]

[0013] The present invention has been invented to solve the problems in the conventional techniques as described above. The three-dimensional surface roughness evaluation method of the present invention is a three-dimensional surface roughness evaluation method for generating three-dimensional surface roughness data of a measurement object, comprising the steps of: 2D laser displacement gauge By , Displacement data is obtained by measuring displacement at regular intervals in the X-axis direction, and the displacement data is averaged in the Y-axis direction within the measurement width of the two-dimensional laser displacement meter to generate reference plane data for each coordinate, and the reference plane data for each coordinate is subtracted from the displacement data for each XY plane coordinate. Measure the surface roughness parameters of the object. The surface roughness parameter related to the roughness height when the laser width at the reference distance of the two-dimensional laser displacement meter is taken as the measurement width is taken as 100%, and the range in which the surface roughness parameter related to the roughness height converges to approximately 100% due to the change in the measurement width in the Y-axis direction is taken as Effective measurement range and death, Within the effective measurement width range identified by the two-dimensional laser displacement meter In the Y-axis direction Displacement data is obtained by measuring the displacement at regular intervals in the X-axis direction within the measurement width. The displacement data is averaged in a Y-axis direction within the specified measurement width range to generate reference plane data for each coordinate; The method is characterized in that the reference surface data of each coordinate is subtracted from the displacement data of each XY plane coordinate to generate three-dimensional surface roughness data of the measurement object.

[0015] Furthermore, the measurement object can be a coating on an object or structure that cannot be transported, and the three-dimensional surface roughness of the coating can be measured directly. Effect of the Invention

[0019] According to the present invention, even if the object to be measured is an object or structure that cannot be transported, it is possible to quickly, continuously, directly and in large quantities obtain surface roughness parameters from the surface of the object to be measured. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic diagram for explaining the configuration of a three-dimensional surface roughness evaluation device in this embodiment. [Diagram 2] FIG. 2 is a schematic diagram for explaining the configuration of the three-dimensional surface roughness data acquisition device. [Diagram 3] FIG. 3 shows displacement data in the XY plane coordinates when measuring a coated plate 1, which is a metal plate having a surface coated with paint (covered with a dry paint film; the same applies below). [Figure 4] FIG. 4 shows reference plane data for each coordinate generated by averaging the displacement data of the XY plane coordinates in FIG. 3 in the Y-axis direction. [Diagram 5] FIG. 5 shows reference plane data in which the inclination of the reference plane data shown in FIG. 4 has been corrected by the least squares method. [Figure 6] FIG. 6 shows three-dimensional surface roughness data obtained by subtracting the reference surface data shown in FIG. 4 from the displacement data shown in FIG. [Figure 7] FIG. 7 is a graph showing the analysis results of the surface roughness parameters obtained from the three-dimensional surface roughness data in FIG. [Figure 8] FIG. 8 is a graph showing the analysis results of the surface roughness parameters obtained for the coated plate 1 as the measurement object using a laser displacement meter attached to an XY stage. [Figure 9] FIG. 9 shows a comparative example of displacement data in the XY plane coordinates when a coated plate 1 is used as a measurement object and measurements are taken over a range of 7.5 mm from the end in the Y-axis direction. [Figure 10] FIG. 10 shows reference plane data for each coordinate generated by averaging the displacement data of the XY plane coordinates in FIG. 9 in the Y-axis direction. [Figure 11] FIG. 11 shows reference plane data in which the inclination of the reference plane data shown in FIG. 10 is corrected by the least squares method. [Figure 12] FIG. 12 shows three-dimensional surface roughness data obtained by subtracting the reference surface data shown in FIG. 10 from the displacement data shown in FIG. [Figure 13] FIG. 13 is a graph showing the analysis results of the surface roughness parameters obtained from the three-dimensional surface roughness data in FIG. [Figure 14] FIG. 14 is a graph showing the relationship between the magnification of the measurement width to the average element length RSm at a measurement width of 32 mm and the ratio (%) of Rz at each measurement width to the maximum height roughness Rz at a measurement width of 32 mm for coated panels 2 to 6. [Figure 15] FIG. 15 is a histogram showing the distribution of surface roughness parameters when the three-dimensional surface roughness of a ship's hull as a measurement object is measured using the three-dimensional surface roughness evaluation device of this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, embodiments (examples) of the present invention will be described in more detail with reference to the drawings. FIG. 1 is a schematic diagram for explaining the configuration of a three-dimensional surface roughness evaluation device in this embodiment, where FIG. 1(a) is a schematic diagram viewed from the side, and FIG. 1(b) is a schematic diagram viewed from the front.

[0022] As shown in Figure 1, the three-dimensional surface roughness evaluation device 10 of this embodiment includes a two-dimensional laser displacement meter 12, a moving mechanism 14, a travel distance reading device 16, a calculation device 18, and a portable battery 20 for operating the two-dimensional laser displacement meter 12, the travel distance reading device 16, and the calculation device 18.

[0023] In addition, when there is no need to check the calculation results at the measurement site, as shown in Figure 2, the displacement data acquired by the two-dimensional laser displacement meter 12 and the travel distance data acquired by the travel distance reading device 16 can be stored in a storage device 32 such as a hard disk drive or flash memory, or can be configured to transmit the data to an external terminal such as that described later using a communication means 34, and can be used as a three-dimensional surface roughness data acquisition device 30.

[0024] By separating the calculation device 18 in this way and using an external terminal as the calculation device 18, the device configuration at the measurement site can be simplified, and the acquired data can be calculated by an external calculation device such as a personal computer, and the calculation results can be displayed.

[0025] The two-dimensional laser displacement meter 12 is not particularly limited, but for example, a Keyence LJ-V7080 (laser width at the reference distance: 32 mm) or the like can be used. In addition, the two-dimensional laser displacement meter 12 is arranged so that the width direction of the two-dimensional laser displacement meter 12 is perpendicular to the movement direction (X-axis direction) of the movement mechanism 14, i.e., coincides with the Y-axis direction, so that displacement data of the coordinate in the Y-axis direction can be read at once at regular intervals.

[0026] In addition, in this embodiment, the moving mechanism 14 has two pairs of wheels (i.e., four wheels) that can move only in a predetermined direction (X-axis direction), but is not particularly limited to this as long as it is a mechanism that can move only in a predetermined direction, and may be, for example, a crawler.

[0027] In this embodiment, a rotary encoder is used as the travel distance reading device 16, and the number of rotations of the wheels, which are the moving mechanism 14, is read to calculate the travel distance based on the circumference and number of rotations of the wheels.

[0028] The movement distance reading device 16 is not limited to this, and may be, for example, a device that reads the movement distance with a scale sensor using a circular scale linked to the movement mechanism 14.

[0029] Furthermore, the calculation device 18 is not particularly limited as long as it can calculate surface roughness parameters and the like based on the displacement data acquired by the two-dimensional laser displacement meter 12 and the movement distance data acquired by the movement distance reading device 16, as described below. For example, it can be configured to transmit the displacement data and the movement distance data to an external terminal such as a tablet computer, a smartphone, or a personal computer, perform calculation processing, and display the calculation results on the external terminal.

[0030] When the calculation device 18 is built into the three-dimensional surface roughness evaluation device 10, a display means for displaying the calculation results such as surface roughness parameters may be provided, or a data output means may be provided and configured to, for example, transmit the calculation results to the above-mentioned external terminal and display the calculation results on the external terminal.

[0031] The portable battery 20 is not particularly limited, and may be any existing secondary battery, such as a lead-acid battery, a nickel-hydrogen secondary battery, or a lithium-ion secondary battery.

[0032] In this embodiment, the three-dimensional surface roughness evaluation device 10 is made easily portable by being equipped with a portable battery 20, but it is also possible to configure the two-dimensional laser displacement meter 12, the computing device 18, etc. to be powered by, for example, an external battery or a commercial power source.

[0033] [Example 1] A specific example of surface roughness evaluation of the measurement object 22 using the three-dimensional surface roughness evaluation apparatus 10 of this embodiment configured as described above will be described below. First, the three-dimensional surface roughness evaluation device 10 is moved over the surface of the object to be measured 22 by the moving mechanism 14, and travel distance data based on the travel distance obtained by the travel distance reading device 16 at regular intervals and displacement data obtained by the two-dimensional laser displacement meter 12 are recorded in the calculation device 18.

[0034] FIG. 3 shows displacement data in the XY plane coordinates measured for a coated plate 1, which is a metal plate having a surface coated with paint, as a measurement target 22. The displacement data shown in Fig. 3 was obtained by the three-dimensional surface roughness evaluation device 10 of this embodiment, which acquired 121 x 121 (121 points in both the X-axis direction and the Y-axis direction) data at a pitch of 250 µm in a measurement range of 30 mm x 30 mm of the coated plate 1. In this embodiment, such measurement was completed within one second.

[0035] Next, the calculation device 18 averaged the displacement data of the XY plane coordinates in the Y-axis direction to generate reference plane data for each coordinate as shown in FIG.

[0036] The reference plane data obtained by correcting the inclination of the reference plane data shown in Fig. 4 using the least squares method is shown in Fig. 5. In Fig. 5, the vertical axis is enlarged to ±30 μm. From Fig. 5, it can be seen that the reference plane data includes the eccentricity of the wheels, which are the moving mechanism 14, of about ±30 μm.

[0037] As described above, the displacement data shown in Fig. 3 contains, in addition to the surface roughness, the inclination of the measurement target 22 and the eccentricity caused by the rolling of the wheels of the moving mechanism 14, and is not suitable for surface roughness evaluation. Therefore, by using the calculation device 18 to subtract the reference surface data shown in Fig. 4 from the displacement data shown in Fig. 3, the inclination contained in the displacement data and the eccentricity caused by the rolling of the wheels of the moving mechanism 14 can be removed, and more accurate three-dimensional surface roughness data can be obtained.

[0038] The three-dimensional surface roughness data thus obtained is shown in FIG. Figure 7 shows the surface roughness parameters Rz (maximum height roughness), RSm (average element length), Rzjis (ten-point average roughness), Ra (arithmetic mean roughness), Rq (root mean square roughness), Rc (average height of the roughness curve), Rsk (skewness), and Rku (kurtosis) calculated from the three-dimensional surface roughness data shown in Figure 6, and graphed with the minimum displacement set to zero.

[0039] The Rz of the coated plate 1 was 78.9 μm, RSm was 3466 μm, Rzjis was 45.1 μm, Ra was 14.2 μm, Rq was 17.6 μm, Rc was 29.9 μm, Rsk was 0.08, and Rku was 2.7.

[0040] [Comparative Example 1] In order to verify the validity of the surface roughness parameters obtained by the three-dimensional surface roughness evaluation device 10 of this embodiment, the surface roughness parameters were measured in the same range as the measurement range of the coated plate 1 in Example 1 using a laser displacement meter (point-shaped laser displacement meter) attached to an XY stage.

[0041] When measuring the measurement range of 30 mm × 30 mm of the measurement object 22 at 250 μm pitches using a laser displacement meter attached to an XY stage, as in Example 1, it is necessary to repeat the process of measuring 121 points at 250 μm pitches in the X-axis direction, moving 250 μm in the Y-axis direction, and then measuring 121 points at 250 μm pitches in the X-axis direction again. For this reason, in this comparative example, such measurements took about 5 minutes.

[0042] FIG. 8 shows a graph of the surface roughness parameters Rz (maximum height roughness), RSm (average element length), Rzjis (ten-point mean roughness), Ra (arithmetic mean roughness), Rq (root mean square roughness), Rc (average height of the roughness curve), Rsk (skewness), and Rku (kurtosis) calculated for the coated panel 1 in Example 1, which were obtained using a laser displacement meter attached to an XY stage.

[0043] The Rz of the painted plate 1 measured using a laser displacement meter was 78.1 μm, RSm was 3561 μm, Rzjis was 50.5 μm, Ra was 13.1 μm, Rq was 16.3 μm, Rc was 35.2 μm, Rsk was −0.11, and Rku was 2.8, which were equivalent to the surface roughness parameters obtained using the three-dimensional surface roughness evaluation device 10 of Example 1.

[0044] [Comparative Example 2] To simulate a case where a two-dimensional laser displacement meter with a laser width of 7.5 mm was used as the two-dimensional laser displacement meter 12, surface roughness parameters were measured within a range of 7.5 mm from the end in the Y-axis direction within the measurement range of the coated plate 1 in Example 1. Note that the configuration of the two-dimensional laser displacement meter 12 other than the laser width was the same as that of the three-dimensional surface roughness evaluation device 10 in Example 1.

[0045] FIG. 9 shows displacement data in the XY plane coordinates for coated plate 1, where 121×31 data (121 points in the X-axis direction and 31 points in the Y-axis direction) were obtained with a pitch of 250 μm over a measurement range of 30 mm×7.5 mm.

[0046] As in Example 1, the displacement data of the XY plane coordinates was averaged in the Y-axis direction to generate the reference plane data of each coordinate shown in Fig. 10. Fig. 11 shows the reference plane data after the inclination is corrected by the least squares method. As in Fig. 5, the eccentricity of the wheels, which are the moving mechanism 14, can be confirmed, but the range of the displacement is larger than that in Fig. 5.

[0047] FIG. 12 shows three-dimensional surface roughness data obtained by subtracting the reference surface data shown in FIG. 10 from the displacement data shown in FIG. 9 and removing the inclination contained in the displacement data and the eccentricity caused by the rolling of the wheels, which are the moving mechanism 14.

[0048] Figure 13 shows the surface roughness parameters Rz (maximum height roughness), RSm (average element length), Rzjis (ten-point average roughness), Ra (arithmetic mean roughness), Rq (root mean square roughness), Rc (average height of the roughness curve), Rsk (skewness), and Rku (kurtosis) calculated from the three-dimensional surface roughness data shown in Figure 12, and graphed with the minimum displacement point set to zero.

[0049] The coated plate 1 measured in Comparative Example 2 had Rz of 56.3 μm, RSm of 3900 μm, Rzjis of 34.9 μm, Ra of 10 μm, Rq of 12.4 μm, Rc of 24.9 μm, Rsk of 0.09, and Rku of 2.8.

[0050] In Comparative Example 2, the surface roughness parameters related to the roughness height, such as Rz, Rzjis, Ra, Rq, and Rc, are smaller than those in Example 1 and Comparative Example 1. This is because the surface roughness shape is included in the reference surface data averaged in the width direction (Y-axis direction) of the two-dimensional laser.

[0051] Furthermore, it is believed that if the measurement width of the two-dimensional laser displacement meter 12 (7.5 mm, the laser width, in Comparative Example 2), which is the length in the Y-axis direction to be averaged, is too small compared to the RSm (average element length) of the measurement object 22 (3900 μm = 3.9 mm in Comparative Example 2), the roughness height will be underestimated.

[0052] In order to properly evaluate the roughness height, it is preferable that the length in the Y-axis direction to be averaged (the measurement width of the two-dimensional laser displacement meter 12) is set to be at least twice the RSm of the measurement object 22. The relationship between the measurement width of the two-dimensional laser displacement meter 12 and the average length RSm of the elements of the measurement object 22 is examined below.

[0053] [Example 2] Table 1 shows the surface roughness parameters obtained by measuring a painted plate 2, which is a metal plate having a surface coated with paint as the measurement object 22, and varying the measurement width of the two-dimensional laser displacement meter 12 to 0.5 mm, 1 mm, 2 mm, 4 mm, 16 mm, and 32 mm, and correcting the parameters using the reference surface data averaged in the width direction (Y-axis direction) of the two-dimensional laser for each measurement width.

[0054] [Table 1]

[0055] As shown in Table 1, the surface parameters related to the roughness height, Rz, Rzjis, Ra, Rq, and Rc, become smaller as the measurement width becomes smaller. This is because the smaller the measurement width becomes, the more the amount of the surface roughness shape included in the reference surface data averaged in the width direction (Y-axis direction) of the two-dimensional laser displacement meter 12 becomes.

[0056] In addition, it was found that the surface parameters related to roughness height, Rz, Rzjis, Ra, Rq, and Rc, all tend to converge to the true value as the measurement width increases. This is because when the measurement width becomes sufficiently larger than RSm, the reference surface data averaged in the width direction (Y-axis direction) of the two-dimensional laser no longer includes the surface roughness shape.

[0057] The maximum height roughness Rz at a measurement width of 32 mm is 111.8 μm, and the average element length RSm is 3325 μm. Table 2 shows the magnification of each measurement width in Table 1 relative to RSm (3325 μm) at a measurement width of 32 mm, and the ratio of each surface roughness parameter at each measurement width in Table 1 to each surface roughness parameter at a measurement width of 32 mm.

[0058] [Table 2]

[0059] The ratio of Rz at each measurement width to Rz at a measurement width of 32 mm was 33.7% when the magnification of the measurement width to RSm at a measurement width of 32 mm was 0.2 times, 57.7% at 0.3 times, 81.7% at 0.6 times, 95.2% at 1.2 times, 101.2% at 2.4 times, and 104.4% at 4.8 times, and there was a clear tendency for the ratio of the measurement width to RSm to converge to 100% as it increased. In particular, it converged to almost 100% when the measurement width was about twice RSm.

[0060] When measuring an object 22 whose surface roughness shape is unknown, the measurement width of the two-dimensional laser displacement meter 12 can be varied in this manner, and a range of the measurement width in which the variation of each surface roughness parameter is small can be selected as the effective measurement width.

[0061] Below, similar measurements were taken on painted plates 3 to 6, which were metal plates with their surfaces painted with paint as the measurement objects 22, and the measurement width of the two-dimensional laser displacement meter 12 was changed to 0.5 mm, 1 mm, 2 mm, 4 mm, 16 mm, and 32 mm. The roughness evaluation results obtained by correcting the results using the reference surface data averaged in the width direction (Y-axis direction) of the two-dimensional laser for each measurement width are shown in Tables 3, 5, 7, and 9, respectively.

[0062] The maximum height roughness Rz of coated plate 3 at a measurement width of 32 mm was 60.4 μm, and the average element length RSm was 1820 μm; the maximum height roughness Rz of coated plate 4 at a measurement width of 32 mm was 146.3 μm, and the average element length RSm was 2200 μm; the maximum height roughness Rz of coated plate 5 at a measurement width of 32 mm was 76.5 μm, and the average element length RSm was 4150 μm; and the maximum height roughness Rz of coated plate 6 at a measurement width of 32 mm was 112.3 μm, and the average element length RSm was 5001 μm.

[0063] Table 4 shows the magnification of each measurement width in Table 3 to RSm (3325 μm) at a measurement width of 32 mm, and the ratio of each surface roughness parameter at each measurement width in Table 3 to each surface roughness parameter at a measurement width of 32 mm.Similarly, Table 6 is for Table 5, Table 8 is for Table 7, and Table 10 is for Table 9.

[0064] [Table 3]

[0065] [Table 4]

[0066] [Table 5]

[0067] [Table 6]

[0068] [Table 7]

[0069] [Table 8]

[0070] [Table 9]

[0071] [Table 10]

[0072] The roughness evaluation results for all of the coated panels 3 to 6 clearly tend to converge to 100% as the magnification of the measurement width relative to RSm increases, and in particular, it is clear that they converge to almost 100% when the measurement width is about twice the RSm.

[0073] FIG. 14 is a graph showing the relationship between the magnification of the measurement width to the average element length RSm at a measurement width of 32 mm and the ratio (%) of Rz at each measurement width to the maximum height roughness Rz at a measurement width of 32 mm for coated panels 2 to 6.

[0074] As shown in FIG. 14, in all of coated plates 2 to 6, when the measurement width was set to about twice RSm or more, the ratio of Rz converged to 100% and did not fluctuate significantly.

[0075] This revealed that if the measurement width of the two-dimensional laser displacement meter 12 is at least twice the average length RSm of the elements of the measurement object 22, the possibility of the surface roughness shape being included in the reference surface data averaged in the width direction (Y-axis direction) of the two-dimensional laser is reduced, and accuracy can be ensured.

[0076] In addition, when using the three-dimensional surface roughness evaluation device 10 of the present invention to measure the surface roughness parameters of a measurement object 22 having unknown roughness, it is also effective to evaluate in advance the average length RSm of the elements of the measurement object 22, for example, using a conventional technology method such as that described above.

[0077] Furthermore, when the average length RSm of the elements of the measurement object 22 cannot be evaluated in advance, as described above, the measurement width of the two-dimensional laser displacement meter 12 can be changed and the range in which there is no significant variation in each surface roughness parameter can be set as the effective measurement width range, thereby enabling highly accurate surface roughness evaluation.

[0078] [Example 3] Using a three-dimensional surface roughness data acquisition device 30 and a computing device 18, which is an external terminal, the three-dimensional surface roughness of a ship's hull was measured as a measurement object 22. The configuration of the three-dimensional surface roughness data acquisition device 30 of Example 3 is similar to that of the three-dimensional surface roughness evaluation device 10 of Example 1, with the computing device 18 omitted. Figure 15(a) is a three-dimensional histogram showing the distribution of Rz (maximum height roughness) and RSm (average element length), which are surface roughness parameters of the hull measured using a three-dimensional surface roughness data acquisition device 30, Figure 15(b) is a histogram showing the distribution of the RSm component of Figure 15(a), and Figure 15(c) is a histogram showing the distribution of the Rz component of Figure 15(a).

[0079] After the hull painting was completed, the three-dimensional surface roughness data acquisition device 30 was used to scan 27 cm in the X-axis direction, acquiring nine pieces of data measuring 30 mm x 30 mm. This process was repeated until 100 measurements were taken across the entire hull, and 900 pieces of data were acquired.

[0080] The measurements of 100 locations were completed in about 2 hours. Of the total 900 measurement points, 620 points were valid data excluding measurement errors, etc., and the acquired data was processed by the external terminal, arithmetic device 18, and the surface roughness parameters Rz (maximum height roughness) was 50.7 μm and RSm (average element length) was 3187 μm.

[0081] In addition, the Rz distribution in the three-dimensional histogram shown in FIG. 15 was from 20 μm to 140 μm, and the RSm distribution was from 1750 μm to 7500 μm. [Explanation of symbols]

[0082] 10 Three-dimensional surface roughness evaluation device 12. Two-dimensional laser displacement gauge 14 Moving mechanism 16 Travel distance reading device 18 Arithmetic unit 20 Portable Battery 22 Measurement Object 30 Three-dimensional surface roughness data acquisition device 32 Storage device 34 Means of communication

Claims

1. A three-dimensional surface roughness evaluation method for generating three-dimensional surface roughness data of a measurement object, comprising the steps of: a two-dimensional laser displacement meter is used to measure displacement at regular intervals in the X-axis direction to obtain displacement data, the displacement data is averaged in the Y-axis direction within the measurement width of the two-dimensional laser displacement meter to generate reference plane data for each coordinate, and the reference plane data for each coordinate is subtracted from the displacement data for each X-Y plane coordinate to measure the surface roughness parameters of the object to be measured; the surface roughness parameter relating to the roughness height when the laser width at the reference distance of the two-dimensional laser displacement meter is taken as the measurement width is set to 100%, and the range in which the surface roughness parameter relating to the roughness height converges to approximately 100% due to a change in the measurement width in the Y-axis direction is taken as the effective measurement width range; The two-dimensional laser displacement meter measures displacement at regular intervals in the X-axis direction within a measurement width in the Y-axis direction within the specified effective measurement width range to obtain displacement data; The displacement data is averaged in a Y-axis direction within the specified measurement width range to generate reference surface data for each coordinate; A three-dimensional surface roughness evaluation method, comprising: subtracting reference surface data of each coordinate from the displacement data of each XY plane coordinate to generate three-dimensional surface roughness data of the measurement object.

2. 2. The three-dimensional surface roughness evaluation method according to claim 1, wherein the measurement object is a coating film on an object or structure that cannot be transported, and the three-dimensional surface roughness of the coating film is directly measured.

Images