JP5929518B2 - Surface shape measuring method and surface shape measuring apparatus - Google Patents

Description

  The present invention relates to a surface shape measuring method and a surface shape measuring apparatus for measuring the dimensions of a groove processed on the surface of an object.

  There are many techniques for processing the surface of an object to form a concavo-convex pattern and improving the function of the object with this concavo-convex pattern. For example, in a magnetic steel sheet, a technique for reducing iron loss of the magnetic steel sheet by performing minute groove processing on the surface is known. In surface processing of an object performed to improve the function of such an object, the shape of the uneven pattern processed on the surface directly affects the quality of the object. For this reason, it is very important to accurately measure the shape of the concavo-convex pattern processed on the surface when managing the manufacturing process and guaranteeing the product quality.

  For example, Patent Document 1 describes a surface shape measurement method for continuously measuring the uneven shape of an object surface on a production line. In this surface shape measurement method, a displacement meter arranged so as to move relative to the object is used to measure the amount of displacement between the displacement meter and the object to obtain a cross-sectional shape, and thus obtained. The depth (or height) and width of the irregularities are calculated from the cross-sectional shape.

  Patent Document 2 describes a technique for measuring the depth and width of a groove based on a reflected light intensity signal in addition to a displacement signal in a surface shape measurement method using an optical displacement meter (laser displacement meter). Has been. The technique described in Patent Literature 2 is a technique for eliminating the abnormal value of the displacement signal detected at the inclined portion of the groove based on the reflected light intensity signal and measuring the depth and width of the groove.

Japanese Patent Laid-Open No. 10-89939 JP2011-99729A

  However, the surface shape measuring method described in Patent Document 2 requires a reflected light intensity signal in addition to the displacement signal as information obtained from the optical displacement meter. Therefore, the surface shape measuring method described in Patent Document 2 is an optical displacement meter that does not output a reflected light intensity signal, or a function that adjusts the intensity of the irradiated light and the light receiving gain to obtain a sufficient reflected light intensity. This type of optical displacement meter cannot be applied.

  In addition, when measuring the shape of a minute groove with a triangulation optical displacement meter, in addition to the problem that the measured value tends to become unstable due to the insufficient amount of light received at the inclined part of the groove, the irradiated light and received light In the displacement meter of the type that adjusts the gain, the amount of received light is unlikely to be insufficient, but instead of receiving the secondary reflected light in which the irradiation light to the inclined portion of the groove is reflected multiple times inside the groove, A phenomenon that the shape of the inclined portion is erroneously recognized occurs. When such misrecognition occurs, an abnormal displacement deeper than the actual groove depth is often observed, and the surface shape measuring method described in Patent Document 1 directly causes an error in the groove depth. There was a problem that would be a measurement.

  Further, when the moving average is used to remove the undulation on the displacement signal as in the surface shape measuring method described in Patent Document 2, the effect of the displacement amount of the groove portion remains on the moving average value. There was a problem that an error occurred when calculating the width and the groove depth.

  The present invention has been made in view of the above, and an object of the present invention is to process disturbances in the displacement data by using only displacement data of the object surface measured by a displacement meter and to remove the disturbance in the displacement data. It is an object of the present invention to provide a surface shape measuring method and a surface shape measuring device capable of measuring the dimension of a groove with high accuracy.

  In order to solve the above-described problems and achieve the object, the surface shape measuring method of the present invention scans the object surface with an optical displacement meter that performs measurement by irradiating the object surface with a light beam, A displacement data acquisition step of acquiring displacement data of the object surface with respect to a displacement meter; a waviness removal step of removing waviness from the displacement data to acquire correction displacement data; and searching for the correction displacement data, and the correction displacement A groove approximate position detecting step for detecting an initial position at which data is lower than a predetermined first threshold as a groove approximate position of a groove processed on the object surface; a groove start point of the groove including the groove approximate position; and A groove width calculating step for calculating a groove end point, and calculating a minimum value of the corrected displacement data limited to a range of a predetermined ratio of the groove width from a center position between the groove start point and the groove end point. A groove that calculates a difference between a minimum value of the corrected displacement data calculated in the deepest position detecting step and a displacement 0 of the corrected displacement data as the depth of the groove processed on the object surface. A depth calculating step.

  In order to solve the above-described problems and achieve the object, the surface shape measuring apparatus of the present invention scans the object surface with an optical displacement meter that performs measurement by irradiating the object surface with light, and A displacement data acquisition unit that acquires displacement data of the object surface with respect to a displacement meter, a displacement data correction unit that acquires correction displacement data by removing waviness from the displacement data, and searches for the correction displacement data to perform the correction A groove approximate position detection unit that detects an initial position at which displacement data is lower than a predetermined first threshold as a groove approximate position of a groove processed on the object surface; and a groove start point of the groove including the groove approximate position And a groove start point / end point detection unit for calculating a groove end point, and a minimum value of the corrected displacement data limited to a predetermined range of the groove width from a center position between the groove start point and the groove end point, Correction Characterized in that it comprises a position groove depth calculating unit that calculates the difference between the minimum value of the data and the correction shift displacement of a data 0 as the depth of the processed groove on the object surface.

  The surface shape measuring method and surface shape measuring apparatus according to the present invention uses only the displacement data of the object surface measured by the displacement meter, eliminates the disturbance in the displacement data, and determines the dimension of the groove processed on the object surface. There is an effect that the measurement can be performed with high accuracy.

FIG. 1 is a schematic diagram illustrating a configuration example of a surface shape measuring apparatus according to an embodiment of the present invention. FIG. 2 is a schematic diagram representing a state of reflection of laser light irradiated to an inclined portion of a groove processed on a steel plate. FIG. 3 is a functional block diagram showing internal processing of the signal processing apparatus according to the embodiment of the present invention. FIG. 4 is a flowchart showing the overall flow of the surface shape measuring method according to the embodiment of the present invention. FIG. 5 is a flowchart showing a method of removing waviness in the surface shape measuring method according to the embodiment of the present invention. FIG. 6 is a graph showing displacement data indicating the state of undulation removal in the surface shape measurement method according to the embodiment of the present invention. FIG. 7 is a flowchart showing a groove width calculation method in the surface shape measurement method according to the embodiment of the present invention. FIG. 8 is a flowchart showing a groove depth calculation method in the surface shape measurement method according to the embodiment of the present invention. FIG. 9 is a graph showing displacement data showing a state of groove width calculation and groove depth calculation in the surface shape measuring method according to the embodiment of the present invention.

  Hereinafter, a surface shape measuring method and a surface shape measuring apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments described below.

[Surface shape measuring device]
FIG. 1 is a schematic diagram illustrating a configuration example of a surface shape measuring apparatus according to an embodiment of the present invention. A surface shape measuring apparatus 1 according to an embodiment of the present invention is an apparatus that measures the shape of a groove processed on the surface of a steel sheet S conveyed on a production line. As shown in FIG. 1, a surface shape measuring apparatus 1 according to an embodiment of the present invention includes a displacement meter head 2, a displacement meter controller 3, a signal processing device 4, a roller encoder 5, and a display device 6. Prepare.

  The displacement meter head 2 is a triangulation type displacement meter having a laser light source 21, a condenser lens 22, an optical position sensor 23, and an imaging lens 24 inside. Laser light 25 emitted from the laser light source 21 is irradiated onto the surface of the steel sheet S as spot light or slit light through the condenser lens 22, and reflected light 26 from the steel sheet S is light transmitted through the imaging lens 24. An image is formed on the light receiving surface of the position sensor 23.

  As shown in FIG. 1, the displacement meter head 2 irradiates the laser beam 25 emitted from the laser light source 21 perpendicularly to the steel sheet S, and the reflected light 26 is formed at a certain angle by the optical position sensor 23. It is the structure which detects. In the case of this configuration, when the distance between the surface of the steel sheet S and the displacement meter head 2 changes, the light receiving position of the reflected light 26 imaged on the optical position sensor 23 changes. That is, the surface shape measuring apparatus 1 shown in FIG. 1 is configured to measure the distance between the surface of the steel sheet S and the displacement meter head 2 by reading the light receiving position of the reflected light 26 in the optical position sensor 23. .

  The displacement meter controller 3 reads the output signal of the optical position sensor 23 while supplying power to the displacement meter head 2 and outputting control signals to the components inside the head. The distance between is calculated. Thereafter, the displacement meter controller 3 outputs the calculated distance between the surface of the steel sheet S and the displacement meter head 2 to the signal processing device 4 as a displacement signal.

For the optical position sensor 23, for example, a light receiving element such as PSD (Position Sensitive Detector), CCD, or CMOS is used. When using the PSD as the light position sensor 23, the two currents I ₁ and I ₂ from both ends of the light receiving element receives the reflected light 26 is output. The displacement meter controller 3 calculates (I ₁ −I ₂ ) / (I ₁ + I ₂ ) using the _two currents I ₁ and I ₂ , and obtains the position of the center of gravity where the reflected light 26 is received from this value. Further, when a CCD or CMOS is used as the optical position sensor 23, since these light receiving elements are arrays of small photodiodes, a received light intensity distribution on the light receiving elements can be obtained. In that case, the displacement meter controller 3 calculates the distance between the surface of the steel sheet S and the displacement meter head 2 based on the barycentric position or peak position of the received light intensity distribution.

  The signal processing device 4 obtains displacement data of the steel sheet S in the entire steel sheet S from the displacement signal output from the displacement meter controller 3 and the pulse signal output from the roller encoder 5 provided on the roller carrying the steel sheet S. It is an apparatus that calculates the shape of the groove that has been restored and processed on the surface of the steel sheet S from the displacement data. The displacement data of the steel sheet S referred to here is data relating to the amount of displacement in the vertical direction on the surface of the steel sheet S. That is, the displacement data of the steel sheet S is data obtained by calculating the difference between the distance between the surface of the steel sheet S and the displacement meter head 2 from a certain reference distance.

  Although the surface shape measuring apparatus 1 shown in FIG. 1 is illustrated as including only a single displacement gauge head 2 for the sake of space, a plurality of displacement gauge heads 2 are arranged in the width direction of the steel sheet S ( If arranged in the Z direction in the figure, the signal processing device 4 can restore the displacement data in the entire steel sheet S. The signal processing device 4 can also restore the displacement data in the entire steel sheet S by configuring the single displacement meter head 2 so as to be able to scan in the width direction (Z direction in the drawing) of the steel sheet S.

  The display device 6 is a device that displays the shape (particularly the groove width and groove depth) of the grooves processed on the surface of the steel sheet S calculated by the signal processing device 4. For example, the display device 6 is a CRT screen display device, and is used by the operator to determine whether or not the shape of the groove processed on the steel plate S is as specified.

  Here, with reference to FIG. 2, a state when the laser beam 25 irradiated to the groove 11 processed on the steel sheet S is reflected will be described.

  FIG. 2 is a schematic diagram illustrating a state of reflection of the laser beam 25 irradiated to the inclined portion of the groove 11 processed on the steel sheet S. FIG. FIG. 2A is a schematic diagram representing the locus of the reflected light 26 due to multiple reflection of the laser light 25 irradiated to the inclined portion of the groove 11 processed on the steel sheet S, and FIG. FIG. 4 is a diagram viewed from the direction of arrow V in FIG. 2A, and is a schematic diagram illustrating a mechanism in which reflected light 26 due to multiple reflection causes the optical position sensor 23 to erroneously recognize the depth of the groove 11.

As shown in FIG. 2A, the laser beam 25 irradiated to the inclined portion of the groove 11 processed on the steel sheet S is reflected and reflected only at the inclined portion (position P _{1 in the} drawing) of the groove 11. The reflected light 26a incident on the position sensor 23 and the reflected light 26b reflected on the inclined portion (position P _{1 in the} figure) of the groove 11 and further reflected on the bottom (position P _{3 in the} figure) and incident on the optical position sensor 23. There is. As shown in FIG. 2A, the light receiving position (position P _{2 in the} drawing) of the reflected light 26a reflected by the inclined portion (position P _{1 in the} drawing) and the bottom (position in the drawing). The position on the optical position sensor 23 is different from the light receiving position (position P _{4 in the} figure) of the reflected light 26 b reflected by P ₃ ) in the optical position sensor 23.

As a result, as shown in FIG. 2B, in the conventional surface shape measuring apparatus, the depth of the groove 11 processed on the steel sheet S may be erroneously recognized. As shown in FIG. 2 (b), the triangulation method, when the light receiving position of the optical position sensor 23 is a diagram in position P _2, in the position in FIG. Height of the steel sheet S (or depth) position When it is recognized that it is P ₁ and the light receiving position in the optical position sensor 23 is the position P ₄ in the figure, the position of the height (or depth) of the steel sheet S is recognized as the position P ₅ in the figure. The height of the result, the triangulation method, the multiple reflection occurs, the position of the height (or depth) of the original steel sheet S despite a diagram in position P _1, the steel sheet S (or depth) position of is from being erroneously recognized as the position P ₅ in FIG.

Therefore, in the surface shape measuring method and the surface shape measuring apparatus according to the embodiment of the present invention, the signal processing method in the signal processing device 4 is devised to eliminate erroneous recognition due to multiple reflection.
[Signal processing equipment]

  FIG. 3 is a functional block diagram showing internal processing of the signal processing device 4 according to the embodiment of the present invention. As shown in FIG. 3, the signal processing device 4 according to the embodiment of the present invention includes a displacement data acquisition unit 41, a displacement data correction unit 42, a groove approximate position detection unit 43, and a groove start / end point detection unit 44. And a groove width calculation unit 45 and a groove depth calculation unit 46.

The displacement data acquisition unit 41 receives a displacement signal from the displacement meter controller 3 and performs A / D conversion, and at the same time receives a pulse signal generated from the roller encoder 5 every time the steel sheet S travels a certain distance. The travel speed or travel position of S is analyzed. As a result, the displacement data acquisition unit 41 restores the displacement data Y ₀ (X) on the steel sheet S from the displacement signal received from the displacement meter controller 3. Here, X means position coordinates in the conveying direction on the steel sheet S, and Y means position coordinates in the height direction of the steel sheet S (see FIG. 1). In addition, although the position coordinate Z of the width direction also exists in the steel plate S, it demonstrates by fixing the position coordinate Z of the width direction to one point in the following description.

The sample point interval ΔX on the steel sheet S in the displacement data Y ₀ (X) is determined by the constant time interval of A / D conversion and the time interval of the pulse signal generated by the roller encoder 5. The interval between the pulse signals generated by the roller encoder 5 means the distance traveled by the steel sheet S during the time interval, and the A / D conversion time interval is the interval at which the sample points of the displacement data Y ₀ (X) are generated. Means. Therefore, the sample point interval ΔX on the steel sheet S is determined by the frequency of the pulse signal included during the time interval of A / D conversion. If the time interval of the pulse signal from the roller encoder 5 is sufficiently short, the displacement data acquisition unit 41 performs A / D conversion in synchronization with this pulse signal, so that sample points on the steel sheet S are obtained. The interval ΔX can also be determined.

Displacement data correction unit 42, from the displacement data acquisition unit displacement data acquired in Y _{0 (X),} displacement data Y ₀ occurring vibration, or of the steel sheet S deflection or the like of the steel sheet S and displacement gauge head 2 _(X) on the The undulation is removed, and corrected displacement data Y ₁ (X) is generated. A method of removing the undulation on the displacement data Y ₀ (X) in the displacement data correction unit 42 will be described in detail later with reference to FIGS. 5 and 6.

The displacement data correction unit 42 preferably performs further filter processing on the corrected displacement data Y ₁ (X) from which the undulation is removed as necessary. Since the corrected displacement data Y ₁ (X) includes measurement noise due to the roughness of the surface of the steel sheet S, a linear low-pass filter such as a moving average filter or a median filter is used to eliminate such noise. It is possible to apply. Note that the filter order (the range in which the average value is calculated in the moving average filter, and the range in which the median value is calculated in the median filter) is determined so that the range of influence on the steel sheet S is constant (that is, the sampling interval ΔX). Inversely proportional). By determining the filter order in this way, the effect of the filter can be kept the same even when the sampling interval ΔX is different.

The groove approximate position detection unit 43 is means for detecting the groove approximate position from the corrected displacement data Y ₁ (X) from which the undulation is removed by the displacement data correction unit 42. The groove approximate position, to search and correct the displacement data correction unit 42 corrects the displacement data Y ₁ a _(X) whereas the (e.g. transfer method of the steel sheet S), the correction displacement data Y _{1 (X)} is a predetermined threshold value L Defined as the first position smaller than ₁ (> 0). Hereinafter referred to that of the position and the groove approximate position X _a. That is, the groove approximate position detecting unit 43 searches from _{one of} the corrected displacement data Y ₁ (X) and first satisfies Y ₁ (X) <− L ₁ with respect to a predetermined threshold L ₁ (> 0). position is detected as the groove approximate position X _a.

Groove start and end point detection unit 44 is a detecting means for detecting the groove start and groove end point corresponding to the groove approximate position X _a detected by the groove approximate position detection unit 43. The grooves start and groove end point, searches the correction displacement data Y _{1 (X)} on both sides as a starting point the groove approximate position X _a, corrected displacement data Y _{1 (X)} is a predetermined threshold value L _{2 (>} 0) Define it as the first position to be larger. Hereinafter, this position of the case of searching backward is described as grooves starting X _s, describes the position of the case of searching the front groove end point X _e. That is, the groove start point / end point detection unit 44 searches the corrected displacement data Y ₁ (X) on both sides using the groove approximate position X _a as a start point, and determines Y ₁ (> for a predetermined threshold L ₂ (> 0). X)> - the _{L 2} become the first position is detected as grooves starting point _{X s} and groove end point _{X e.}

Groove width calculating unit 45 calculates the difference between the groove start point X _s and groove end point X _e where the groove start and end points detecting section 44 detects, calculates the groove width W of the processed groove on the steel plate S . That is, the groove width calculation unit 45 calculates the groove width W of the groove processed on the steel sheet S by calculating W = X _e −X _s .

On the other hand, the groove depth calculating unit 46, calculation unit from the displacement data correction unit 42 corrects the displacement data Y ₁ obtained by removing undulation by _(X), calculates the groove depth D of the groove corresponding to the groove approximate position X _a It is. To calculate the groove depth D of the groove corresponding to the groove approximate position X _a, groove depth calculating unit 46, the center of the groove start point X _s detected by the groove start and end points detecting section 44 and the groove end point X _e A section having a predetermined ratio R (0 <R <1) of the groove width W (that is, a length of W × R) is set as a groove depth search range, and correction displacement data Y ₁ ( Search for the minimum value of X). Then, the groove depth calculation unit 46 sets the difference (that is, absolute value) between the minimum value of the corrected displacement data Y ₁ (X) and the displacement 0 as the groove depth D of the groove processed on the steel sheet S. calculate. The groove depth calculation unit 46 may calculate an average value of Y ₁ (X) in the same range, and may calculate a difference (absolute value) from the displacement 0 as the groove depth D. An appropriate calculation method can be selected depending on characteristics or the like.

  After the groove width W and the groove depth D of the groove of the steel sheet S are calculated by the groove width calculation unit 45 and the groove depth calculation unit 46, the groove width W and the groove depth D are displayed on the display device 6. .

[Surface shape measurement method]
Next, the surface shape measuring method according to the embodiment of the present invention will be described with reference to FIGS. 4 to 9.

  FIG. 4 is a flowchart showing the overall flow of the surface shape measuring method according to the embodiment of the present invention. As shown in FIG. 4, the surface shape measuring method according to the embodiment of the present invention is roughly divided into a displacement data acquisition step (step STP1), a swell removal step (step STP2), and a groove width calculation step (step). STP3) and a groove depth calculation step (step STP4). Since the displacement data acquisition step (step STP1) is a normal process as a premise of the surface shape measurement method, hereinafter, the undulation removal step (step STP2), the groove width calculation step (step STP3), and the groove depth calculation will be described. The surface shape measuring method according to the embodiment of the present invention will be described separately in steps (step STP4).

  FIG. 5 is a flowchart showing a method of removing waviness in the surface shape measuring method according to the embodiment of the present invention, and FIG. 6 is displacement data showing a state of waviness removal in the surface shape measuring method according to the embodiment of the present invention. It is a graph which shows. FIG. 7 is a flowchart showing a method for calculating the groove width in the surface shape measuring method according to the embodiment of the present invention. FIG. 8 shows a method for calculating the groove depth in the surface shape measuring method according to the embodiment of the present invention. It is a flowchart to show. FIG. 9 is a graph showing displacement data showing a state of groove width calculation and groove depth calculation in the surface shape measuring method according to the embodiment of the present invention.

Hereinafter, the swell removal step (step STP2) will be described. As shown in FIG. 5, in the method for removing waviness in the surface shape measurement method according to the embodiment of the present invention, the displacement data correction unit 42 starts by smoothing the displacement data Y ₀ (X) ( Step S1).

As shown in FIG. 6A, the displacement data Y ₀ (X) acquired by the displacement data acquisition unit 41 is large as a whole due to the vibration of the steel plate S and the displacement meter head 2 and the deflection of the steel plate S. The so-called swell component is included. Then, the displacement showing the shape of the groove indicated by Zuchu symbol a ₁ ~a ₄ is confirmed in the displacement data Y accompanied by components of waviness _{0 (X).} This undulation component is an impeding factor for accurately measuring the groove shape.

Therefore, in the waviness elimination method in the surface shape measuring method according to an embodiment of the present invention, the displacement data correction unit 42, as smoothing of the displacement data Y _{0 (X),} relative displacement data Y _{0 (X)} A moving average process (or other low-pass filter process) is performed (step S1). The graph shown in FIG. 6B shows smoothed data Y _m (X) obtained by the displacement data correction unit 42 performing a moving average process on the displacement data Y ₀ (X). In this moving average process, the operator can set an average width such that the shape of the groove is not visible.

Thereafter, the displacement data correction unit 42, by performing the subtraction processing from subjected to smoothing processing the smoothed data Y _{m (X)} displacement data Y _{0 (X),} a swell from the displacement data Y _{0 (X)} is removed (Step S2). FIG. 6C is a graph showing the corrected displacement data Y ₁ (X) obtained by removing the undulation from the displacement data Y ₀ (X) as described above. In the corrected displacement data Y ₁ (X), the undulation component is subtracted from the displacement data Y ₀ (X), so that the displacement (height) of the surface of the steel sheet S is normalized to 0.

By the way, paying attention to the portions indicated by b _{1 to} b ₄ in FIG. 6B, the smoothed data Y _m (X) has a wide, shallow and recessed shape. The wide and shallowly depressed shapes in b _{1 to} b ₄ are due to the influence of the grooves a _{1 to} a ₄ in the displacement data Y ₀ (X) on the moving average process. As a result, even in the shape of the corrected displacement data Y ₁ (X) shown in FIG. 6C, the displacement is slightly larger than 0 before and after the positions shown in c _{1 to} c ₄ (the shape slightly raised). And an error is generated in the evaluation of the groove depth and the groove width.

Therefore, in order to remove such influence, a weighted smoothing process described below is performed on the displacement data Y ₀ (X) (step S3), and the smoothed data Y _{m ′} ( X) is subtracted from the displacement data Y ₀ (X) (step S4).

For the weighted smoothing process in step S3, the displacement data correction unit 42 firstly has a predetermined threshold value L _m for determining a groove portion in the corrected displacement data Y ₁ (X) as shown in FIG. 6C. (> 0) is set. Then, in accordance with the threshold value L _m, a weighting function is defined as follows.
B (X) = 1 (when | Y ₁ (X) | ≦ L _m )
B (X) = 0 (when | Y ₁ (X) |> L _m )

The displacement data correction unit 42 uses the weighting function B (X), performs weighted smoothing process displacement data _Y 0 (X) (step S3). The following formula is a function of the weighted moving average shown. The calculated modified smoothed data Y _{m ′} (X) is a moving average that is not included in the moving average for the position X where B (X) = 0. However, h (> 0) is a half value of the moving average width.

FIG. 6D shows a graph of the modified smoothed data Y _{m ′} (X) when the weighted averaging process is performed on the displacement data Y ₀ (X). When attention is paid to the positions indicated by d ₁ to d ₄ in FIG. 6D, it can be seen that the wide and shallow depression shape as seen in b _{1 to} b ₄ in FIG.

As a final process of undulation removal, additional corrected displacement data Y _{1 ′} (X) is calculated by subtracting the deformed smoothed data Y _{m ′} (X) from the displacement data Y ₀ (X) (step S4).

FIG. 6E is a graph showing the corrected displacement data Y _{1 ′} (X) that has been subjected to swell removal as described above. As shown in FIG. 6E, the state where the displacement is slightly larger than 0 (the shape slightly raised) is eliminated at the positions of the grooves indicated by e _{1 to} e ₄ in the drawing. In the following description, the corrected displacement data Y ₁ (X) and the additional corrected displacement data Y _{1 ′} (X) are not distinguished from each other, and are described as corrected displacement data Y ₁ (X). The application of the additional correction is not excluded.

Hereinafter, the groove width calculating step (step STP3) will be described. As shown in FIG. 7, in the method for calculating the groove width in the surface shape measuring method according to the embodiment of the present invention, the approximate groove position of the groove first processed by the groove approximate position detection unit 43 on the surface of the steel sheet S is shown. _Xa is detected (step S5). The groove approximate position detection unit 43 searches from _{one of} the corrected displacement data Y ₁ (X) corrected by the displacement data correction unit 42 (for example, the conveyance direction of the steel plate S), and with respect to a predetermined threshold L ₁ (> 0). Then, the first position where the corrected displacement data Y ₁ (X) is Y ₁ (X) <− L ₁ is detected as the groove approximate position X _a (see FIG. 9).

Thereafter, the groove start and end point detection unit 44, searches the correction displacement data _Y 1 (X) on both sides from the groove approximate position _{X a} (Step S6), and detects the groove start point _{X s} and groove end point _{X e} (step S7). The groove start / end point detection unit 44 searches backward for the corrected displacement data Y ₁ (X), and the corrected displacement data Y ₁ (X) is Y ₁ (X)> with respect to a predetermined threshold L ₂ (> 0). the first position at which -L ₂ is detected as a groove starting point _{X s.} Similarly, the groove start / end point detector 44 searches forward for the corrected displacement data Y ₁ (X) and detects the first position where Y ₁ (X)> − L ₂ as the groove end point X _e (FIG. 9).

Using the detected groove starting X _s and groove end point X _e as described above, the groove width calculating unit 45 calculates the groove width W of the processed groove in the surface of the steel sheet S. That is, the groove width calculating unit 45 calculates the distance between the groove start point _{X s} and groove end point _{X e} as groove width W (step S8). That is, W = X _e −X _s is calculated.

Next, the groove depth calculation step (step STP4) will be described. As shown in FIG. 8, the groove depth calculation method in the surface shape measuring method according to an embodiment of the present invention, the groove depth calculating unit 46, and a groove start point X _s and groove end point X _e groove of the central calculating the section _{W R} (step S9) begins. Specifically, the groove depth calculation unit 46 calculates the center position between the groove start point X _s and the groove end point X _e, and a range (W × R) of a predetermined ratio R to the groove width W from the center position. the calculated as a central portion W _R of the groove (see FIG. 9).

Thereafter, the groove depth calculating unit 46 limits the corrected displacement data _Y 1 (X) in the range of the central portion _{W R} of the above-mentioned groove (step S10). Then, the groove depth calculation unit 46 calculates the minimum value of the corrected displacement data Y ₁ (X) within this limited range (step S11).

Finally, groove depth calculating unit 46, the correction displacement data Y ₁ from displacement 0 _(X), the correction displacement data Y _{1 (X} within a limited range in the central portion W _R of the groove which is calculated in step S11 The depth D of the groove is calculated by calculating the distance to the minimum value of () (step S12).

As described above, by the groove depth calculating unit 46 calculates the depth D of the groove, even when the abnormal value on the displacement data as position P ₆ in FIG. 9 is generated, the influence It is possible to accurately measure the groove depth without receiving. The ratio R of the search section width to the groove width W may be set to a size that can avoid an abnormal value at the groove inclined portion. For example, the width is preferably about 30% to 10% with respect to the groove width W.

In an example in which grooving is performed on an electromagnetic steel plate, since the grooves are continuously processed at regular intervals, the displacement data usually includes a plurality of groove cross-sectional shapes. When applying the surface shape measuring method according to an embodiment of the present invention to such an example, from the position after the end point X _e of the detected groove, repeated series of steps of further detecting and measuring a next groove-shaped portions applied By doing so, it is possible to continuously measure a large number of groove shapes included in the displacement data.

  As described above, in the surface shape measuring method according to the embodiment of the present invention, the surface of the steel plate S is scanned by the displacement meter head 2 that irradiates the steel plate S with light and performs triangulation, and the steel plate S with respect to the displacement meter head 2 is scanned. A displacement data acquisition step for acquiring the displacement data of the surface, a swell removal step for removing the undulation from the displacement data and acquiring the corrected displacement data, and searching for the corrected displacement data. The corrected displacement data is a predetermined first threshold value. A groove approximate position detecting step for detecting an initial position lower than the groove as a groove approximate position of the groove processed on the surface of the steel sheet S, and a groove width calculation for calculating a groove start point and a groove end point of the groove including the approximate groove position Calculated at the step, the deepest position detection step that calculates the minimum value of the corrected displacement data limited to the range of the width of the groove width from the center position of the groove start point and groove end point, and the deepest position detection step And a groove depth calculating step for calculating the difference between the minimum value of the corrected displacement data and the displacement 0 of the corrected displacement data as the depth of the groove processed on the surface of the steel sheet S. By using only the displacement data on the surface of the steel sheet S, the disturbance in the displacement data can be eliminated, and the dimensions of the grooves processed on the surface of the steel sheet S can be measured with high accuracy.

DESCRIPTION OF SYMBOLS 1 Surface shape measuring device 2 Displacement meter head 3 Displacement meter controller 4 Signal processing device 5 Roller encoder 6 Display device 11 Groove 21 Laser light source 22 Condensing lens 23 Optical position sensor 24 Imaging lens 25 Laser beam 26 Reflected light 41 Acquisition of displacement data Unit 42 Displacement data correction unit 43 Groove approximate position detection unit 44 Groove start / end point detection unit 45 Groove width calculation unit 46 Groove depth calculation unit

Claims (6)

Displacement data acquisition step of scanning the object surface with an optical displacement meter that performs measurement by irradiating the object surface with light, and acquiring displacement data of the object surface with respect to the optical displacement meter;
A waviness removing step of removing waviness from the displacement data and obtaining corrected displacement data;
A groove approximate position detecting step of searching the corrected displacement data and detecting a first position where the corrected displacement data is lower than a predetermined first threshold as a groove approximate position of a groove processed on the object surface;
A groove width calculating step for calculating a groove start point and a groove end point of the groove including the groove approximate position;
A deepest position detecting step for calculating a minimum value of the corrected displacement data limited to a range of a predetermined width of the groove width from a center position between the groove start point and the groove end point;
A groove depth calculating step for calculating a difference between a minimum value of the corrected displacement data calculated in the deepest position detecting step and a displacement 0 of the corrected displacement data as a depth of a groove processed on the object surface;
A surface shape measuring method comprising: The groove width calculating step includes:
A groove start point detecting step of searching the corrected displacement data backward from the groove approximate position and detecting, as a groove start point of the groove, an initial position where the corrected displacement data is larger than a predetermined second threshold;
A groove end point detecting step of searching the corrected displacement data forward from the groove approximate position and detecting a first position where the corrected displacement data is greater than a predetermined second threshold as a groove end point of the groove;
A difference calculating step of calculating a distance between a groove start point and a groove end point of the groove as a width of the groove processed on the object surface;
The surface shape measuring method according to claim 1, comprising: The swell removal step includes:
A smoothing step of smoothing the displacement data to obtain temporary smoothed data;
A first subtraction step of subtracting the temporary smoothing data from the displacement data to obtain temporary correction displacement data;
Weighted smoothing that obtains smoothed data by performing weighted moving average processing on the displacement data using a weighting function that performs case classification depending on whether or not the absolute value of the provisionally corrected displacement data is equal to or less than a predetermined third threshold value Steps,
A second subtraction step of subtracting the smoothed data from the displacement data to obtain the corrected displacement data;
The surface shape measuring method according to claim 1 or 2, characterized by comprising: A displacement data acquisition unit that scans the object surface with an optical displacement meter that performs measurement by irradiating the object surface with light, and acquires displacement data of the object surface with respect to the optical displacement meter;
A displacement data correction unit that obtains corrected displacement data by removing waviness from the displacement data;
A groove approximate position detection unit that searches the corrected displacement data and detects an initial position at which the corrected displacement data is lower than a predetermined first threshold as a groove approximate position of a groove processed on the object surface;
A groove start point / end point detector for calculating a groove start point and a groove end point of the groove including the groove approximate position;
A minimum value of the corrected displacement data limited to a range of a predetermined ratio of the groove width is calculated from a center position between the groove start point and the groove end point, and the minimum value of the corrected displacement data and the displacement of the corrected displacement data are calculated. A groove depth calculation unit for calculating a difference from 0 as a depth of a groove processed on the object surface;
A surface shape measuring apparatus comprising: The groove start / end point detector
Searching for the corrected displacement data backward from the groove approximate position, and detecting a first position at which the corrected displacement data is greater than a predetermined second threshold as a groove start point of the groove;
A groove end point detecting means for searching the corrected displacement data forward from the groove approximate position and detecting, as a groove end point of the groove, a first position where the corrected displacement data is larger than a predetermined second threshold;
A difference calculating means for calculating a distance between a groove start point and a groove end point of the groove as a width of the groove processed on the object surface;
The surface shape measuring apparatus according to claim 4, comprising: The displacement data correction unit is
Smoothing means for smoothing the displacement data to obtain temporary smoothed data;
First subtraction means for subtracting the temporary smoothing data from the displacement data to obtain temporary correction displacement data;
Weighted smoothing that obtains smoothed data by performing weighted moving average processing on the displacement data using a weighting function that performs case classification depending on whether or not the absolute value of the provisionally corrected displacement data is equal to or less than a predetermined third threshold value Means,
Second subtracting means for subtracting the smoothed data from the displacement data to obtain the corrected displacement data;
The surface shape measuring device according to claim 4 or 5, characterized by comprising:

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