Circumferential surface measuring device and circumferential surface measuring method

Abstract

To provide a circumferential surface measuring device and a circumferential surface measuring method that accurately measure the surface shape of a workpiece in which innumerable convex or concave fine portions are periodically dispersed and remain.SOLUTION: A circumferential surface measuring device includes: measurement direction identification means 162a for identifying a direction in which an arrangement cycle of a ridge line PL and a valley line VL exists for one or more cycles as a measurement direction for a cutting object W; and a drive control unit 161 that controls a motor 123 and a probe movement mechanism 150 to move a measurement probe 130 from a predetermined measurement start point in the measurement direction so as to pass through at least one concave portion V of the cutting object W and at least one convex fine portion T of the cutting object W.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a circumferential surface measuring device and a circumferential surface measuring method. [Background technology]

[0002] A conventional method for inspecting a cylindrical body is known in which unevenness is detected by measuring the circumferential runout, which is the maximum value of the radial displacement on one circumference relative to the axis of the cylinder, along the axial direction of the cylinder, and the surface of the cylinder is spirally scanned in the axial direction (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-292539 A (particularly, claim 3) Summary of the Invention [Problem to be solved by the invention]

[0004] When attempting to use the above-mentioned cylindrical inspection method to detect a workpiece that has been cut using low-frequency vibration cutting to leave countless fine convex features periodically distributed on its circumferential surface, there is a risk that the surface shape of the workpiece cannot be measured correctly if only concave features are present on the scanning path.

[0005] Therefore, the present invention is intended to solve the problems of the prior art as described above, that is, the object of the present invention is to provide a circumferential surface measuring device and a circumferential surface measuring method that can accurately measure the surface shape of a workpiece on which countless convex or concave fine portions remain distributed periodically. [Means for solving the problem]

[0006] First, the present invention is a circumferential surface measuring device for measuring the surface shape of a workpiece on which a countless number of convex fine portions and a countless number of concave portions formed between the convex fine portions remain periodically distributed on the circumferential surface, and on which linear ridge lines connecting the vicinity of the apexes of the convex fine portions and having the greatest unevenness in the height direction and linear valley lines parallel to the ridge lines and having the smallest unevenness in the height direction are periodically arranged on the circumference, the circumferential surface measuring device comprising: a measuring probe for measuring the surface shape of the workpiece along the circumferential surface of the workpiece; and a measuring device for rotating at least one of the workpiece and the measuring probe around the axis of the workpiece. the measurement probe is provided with a rotation means for rotating the measurement probe, a measurement point moving means for linearly moving at least one of the measurement probe and the workpiece parallel to the axis of the workpiece, a measurement direction identifying means for identifying a direction in which the arrangement period of the ridge lines and the valley lines exists for one or more periods as the measurement direction for the workpiece, and a drive control means for controlling the rotation means and the measurement point moving means to move the measurement probe from a predetermined measurement starting point in the measurement direction so as to pass through at least one recessed portion of the workpiece and at least one convex fine portion of the workpiece. Here, "infinite" in the present invention means "so many that it cannot be counted", but it goes without saying that it can also mean "two or more".

[0007] Secondly, when the distance between the inspection path extending from the measurement starting point in the measurement direction and the apex of the convex fine portion is arranged in ascending order, the distance between the apex of the nth (n = 1, 2, etc.) convex fine portion and the inspection path is the second smallest after the distance between the apex of the n+1th convex fine portion and the inspection path, and the difference between the distance between the apex of the nth convex fine portion and the inspection path and the distance between the apex of the n+1th convex fine portion and the inspection path is less than a predetermined interval value.

[0008] Thirdly, the measurement direction specifying means specifies the measurement direction based on a result of scanning the measurement probe along the circumferential surface of the workpiece.

[0009] Fourthly, the workpiece is characterized in that it is cut by low-frequency vibration cutting.

[0010] Fifthly, the measuring probe is provided in a plurality of locations.

[0011] Sixth, a circumferential surface measuring device for measuring the surface shape of a workpiece on which a countless number of concave fine portions and a countless number of convex portions formed between the concave fine portions remain periodically distributed on the circumferential surface, and linear valley lines that connect the vicinity of the apexes of the concave fine portions and have the greatest unevenness in the height direction and linear ridge lines that are parallel to the valley lines and have the smallest unevenness in the height direction are periodically arranged on the circumference, the circumferential surface measuring device comprising: a measuring probe that measures the surface shape of the workpiece along the circumferential surface of the workpiece; and a measuring device that rotates at least one of the workpiece and the measuring probe around the axis of the workpiece. the measurement probe and the workpiece in a linear motion parallel to the axis of the workpiece; a measurement direction determining means for determining a direction in which the arrangement period of the ridge lines and the valley lines exists for one or more periods as the measurement direction for the workpiece; and a drive control means for controlling the rotation means and the measurement point moving means to move the measurement probe from a predetermined measurement starting point in the measurement direction so as to pass through at least one convex portion of the workpiece and at least one concave fine portion of the workpiece.

[0012] Seventh, a measurement probe for measuring the surface shape of a workpiece along a circumferential surface of the workpiece on which an innumerable number of convex fine portions and an innumerable number of concave portions formed between the convex fine portions remain periodically distributed on the circumferential surface, and on which linear ridge lines connecting the vicinity of the apexes of the convex fine portions and having the greatest unevenness in the height direction and linear valley lines parallel to the ridge lines and having the smallest unevenness in the height direction are periodically arranged on the circumference, a rotation means for rotating at least one of the workpiece or the measurement probe around the axis of the workpiece, a measurement point moving means for linearly moving at least one of the measurement probe or the workpiece parallel to the axis of the workpiece, and a measurement point moving means for moving at least one of the measurement probe or the workpiece linearly parallel to the axis of the workpiece, and a measurement point moving means for moving the periphery of the arrangement of the ridge lines and the valley lines. a measurement step in which the measurement direction specifying means specifies a direction in which the ridge line and the valley line exist for one or more periods as the measurement direction for the workpiece; and a measurement step in which the drive control means moves the measurement probe from a predetermined measurement starting point in the measurement direction so as to pass through at least one recessed portion of the workpiece and at least one convex fine portion of the workpiece.

[0013] Eighth, a measurement probe for measuring the surface shape of a workpiece along a circumferential surface of the workpiece on which countless concave fine portions and countless recesses formed between the concave fine portions remain dispersed periodically on the circumferential surface, and linear valley lines that connect the vicinity of the apexes of the concave fine portions and have the greatest unevenness in the height direction and linear ridge lines that are parallel to the valley lines and have the smallest unevenness in the height direction are periodically arranged on the circumference, a rotation means for rotating at least one of the workpiece or the measurement probe around the axis of the workpiece, a measurement point moving means for linearly moving at least one of the measurement probe or the workpiece parallel to the axis of the workpiece, and a measurement point moving means for moving at least one of the measurement probe or the workpiece in a straight line parallel to the axis of the workpiece, and an arrangement of the ridge lines and the valley lines. A circumferential surface measuring method using a circumferential surface measuring device that measures the surface shape of the workpiece and is equipped with a measurement direction identifying means for identifying a direction in which the ridge line and the valley line have one or more periods as the measurement direction for the workpiece, and a drive control means for controlling the rotation means and the measurement point moving means, characterized in that the method includes a measurement direction identifying step in which the measurement direction identifying means identifies a direction in which the ridge line and the valley line have one or more periods as the measurement direction for the workpiece, and a measurement step in which the drive control means moves the measurement probe from a predetermined measurement starting point in the measurement direction so as to pass through at least one convex portion of the workpiece and at least one concave fine portion of the workpiece. Effect of the Invention

[0014] The present invention can achieve the following effects. (1) By providing a measurement direction identifying means for identifying a direction in which the arrangement period of ridge lines and valley lines exists for one or more periods as the measurement direction for the workpiece, and a drive control means for controlling the rotation means and the measurement point moving means to move the measurement probe from a predetermined measurement starting point in the measurement direction so as to pass through at least one concave portion of the workpiece and at least one convex fine portion of the workpiece, the measurement probe will reliably pass through the convex fine portion of the workpiece regardless of where the measurement starting point is on the circumferential surface of the workpiece. Therefore, regardless of where the measurement starting point is on the circumferential surface of the workpiece, the surface shape of the workpiece on which countless convex fine portions are periodically distributed can be accurately measured.

[0015] (2) When the distance between the inspection path extending from the measurement starting point in the measurement direction and the apex of the convex fine portion is arranged in ascending order, the distance between the apex of the nth (n = 1, 2, etc.) convex fine portion and the inspection path is the next smallest after the distance between the apex of the nth convex fine portion and the inspection path. If the difference between the distance between the apex of the nth convex fine portion and the inspection path and the distance between the apex of the nth convex fine portion and the inspection path and the distance between the apex of the n+1th convex fine portion and the inspection path is less than a predetermined interval value, the inspection direction is likely to pass near the convex fine portion regardless of the measurement starting point, and the surface shape of the workpiece on which countless convex fine portions remain distributed periodically can be measured more accurately.

[0016] (3) The measurement direction determining means determines the measurement direction based on the results of scanning the measurement probe along the circumferential surface of the workpiece. This allows the measurement direction to be determined in accordance with the workpiece actually being measured, making it possible to measure the surface shape of the workpiece more accurately.

[0017] (4) Since the workpiece is a workpiece that has been cut by low-frequency vibration cutting processing, countless convex fine portions and countless concave portions formed between these convex fine portions remain periodically distributed on the circumferential surface, and linear ridge lines that connect the vicinity of the apexes of the convex fine portions and have the greatest unevenness in the height direction, and linear valley lines that are parallel to this ridge line and have the least unevenness in the height direction, are periodically arranged on the circumference. Even if the workpiece is such a cut object, the above-mentioned configuration of the circumferential surface measuring device ensures that the measurement probe passes through the convex fine parts of the workpiece, so that regardless of where the measurement starting point is on the circumferential surface of the workpiece, it is possible to accurately measure the surface shape of the workpiece, in which countless convex fine parts are formed in a periodically dispersed manner by the low-frequency vibration cutting process.

[0018] (5) By installing multiple measurement probes, multiple points can be measured simultaneously, which increases the number of measurement points per unit time and enables the measurement data to be more densely packed. In addition, the tip shapes of multiple measurement probes can be made different from one another, so that a measurement probe with a small tip radius can be used for roughness measurement, a measurement probe with a large tip radius can be used for waviness / shape measurement, and a measurement probe with a special tip shape suitable for a specific measurement can be used in combination.

[0019] (6) By providing a measurement direction identifying means for identifying a direction in which the arrangement period of ridge lines and valley lines exists for one or more periods as the measurement direction for the workpiece, and a drive control means for controlling the rotation means and the measurement point moving means to move the measurement probe from a predetermined measurement starting point in the measurement direction so as to pass through at least one convex portion of the workpiece and at least one concave fine portion of the workpiece, the measurement probe will reliably pass through the concave fine portion of the workpiece regardless of where the measurement starting point is on the circumferential surface of the workpiece. Therefore, regardless of where the measurement starting point is on the circumferential surface of the workpiece, the surface shape of the workpiece on which countless concave fine portions are periodically distributed can be accurately measured.

[0020] (7) The present invention includes a measurement direction determining step in which the measurement direction determining means determines the direction in which the arrangement period of ridge lines and valley lines has one or more periods as the measurement direction for the workpiece, and a measurement step in which the drive control means moves the measurement probe from a predetermined measurement starting point in the measurement direction so as to pass through at least one concave portion of the workpiece and at least one convex fine portion of the workpiece. Therefore, regardless of where the measurement starting point is on the circumferential surface of the workpiece, the measurement probe will reliably pass through the convex fine portion of the workpiece. Therefore, regardless of where the measurement starting point is on the circumferential surface of the workpiece, the surface shape of the workpiece on which countless convex fine portions are periodically distributed can be accurately measured.

[0021] (8) The present invention includes a measurement direction determining step in which the measurement direction determining means determines the direction in which the arrangement period of ridge lines and valley lines has one or more periods as the measurement direction for the workpiece, and a measurement step in which the drive control means moves the measurement probe from a predetermined measurement starting point in the measurement direction so as to pass through at least one convex portion of the workpiece and at least one concave fine portion of the workpiece. Therefore, regardless of where the measurement starting point is on the circumferential surface of the workpiece, the measurement probe will reliably pass through the concave fine portion of the workpiece. Therefore, regardless of where the measurement starting point is on the circumferential surface of the workpiece, the surface shape of the workpiece on which countless concave fine portions are periodically distributed can be accurately measured. [Brief description of the drawings]

[0022] [Figure 1A] 1 is a perspective view of a workpiece that is an object to be measured by a cut circumferential surface measuring device according to an embodiment of the present invention; [Figure 1B] A partial enlarged view of FIG. 1A. [Figure 1C] The diagram shown in Fig. 1B . [Figure 1D] Exploded view of Figure 1B. [Diagram 2] 1 is a schematic perspective view of a cutting circumferential surface measuring device according to an embodiment of the present invention; [Diagram 3] 11 is a flowchart showing a procedure for identifying a measurement direction. [Figure 4A] This is a diagram showing the results of imaging the 3D data of the surface shape of the workpiece. [Figure 4B] FIG. 4B shows convex fine details and feature orientation relative to FIG. 4A. [Figure 4C] FIG. 13 is a diagram showing a measurement direction range for a first feature direction. [Figure 4D] FIG. 11 is a diagram showing a measurement direction range for a second feature direction. [Figure 4E] FIG. 11 is a diagram showing a measurement direction range for a third feature direction. [Figure 4F] FIG. [Figure 4G] 11A and 11B are diagrams illustrating a method for identifying candidates for a measurement direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The present invention is a circumferential surface measuring device for measuring the surface shape of a workpiece on which a countless number of convex fine portions and a countless number of concave portions formed between these convex fine portions remain periodically distributed on the circumferential surface, and on which a linear ridge line that connects the vicinity of the apexes of the convex fine portions and has the greatest unevenness in the height direction and a linear valley line that is parallel to the ridge line and has the least unevenness in the height direction are periodically arranged on the circumference, the device comprising a measuring probe that measures the surface shape of the workpiece along the circumferential surface of the workpiece, a rotating means that rotates at least one of the workpiece or the measuring probe around the axis of the workpiece, and a measuring device that rotates at least one of the measuring probe and the workpiece around the axis of the workpiece. The specific embodiment of the measurement probe is not limited as long as it is equipped with a measurement point moving means for moving at least one of the measurement probes in a straight line parallel to the axis of the workpiece, a measurement direction identifying means for identifying a direction in which the arrangement period of ridge lines and valley lines exists at least once as the measurement direction for the workpiece, and a drive control means for controlling the rotation means and the measurement point moving means to move the measurement probe from a predetermined measurement starting point in the measurement direction so as to pass through at least one concave portion of the workpiece and at least one convex fine portion of the workpiece, and capable of accurately measuring the surface shape of a workpiece on which countless concave fine portions remain distributed periodically.

[0024] The present invention also provides a circumferential surface measuring device for measuring the surface shape of a workpiece on which a countless number of minute concave portions and a countless number of minute convex portions formed between these minute concave portions remain periodically distributed on the circumferential surface, and on which linear valley lines connecting the vicinity of the apexes of the minute concave portions and having the greatest unevenness in the height direction and linear ridge lines parallel to the valley lines and having the smallest unevenness in the height direction are periodically arranged on the circumference, the device comprising a measuring probe for measuring the surface shape of the workpiece along the circumferential surface of the workpiece, a rotating means for rotating at least one of the workpiece or the measuring probe around the axis of the workpiece, and a measuring device for measuring the surface shape of the workpiece by rotating the measuring probe or the measuring probe by rotating the measuring probe and ... The specific embodiment of the measurement probe is not limited as long as it is equipped with a measurement point moving means for moving at least one of the measurement probes in a straight line parallel to the axis of the workpiece, a measurement direction identifying means for identifying a direction in which the arrangement period of ridge lines and valley lines exists at least once as the measurement direction for the workpiece, and a drive control means for controlling the rotation means and the measurement point moving means to move the measurement probe from a predetermined measurement starting point in the measurement direction so as to pass through at least one convex portion of the workpiece and at least one concave fine portion of the workpiece, and capable of accurately measuring the surface shape of a workpiece on which countless convex fine portions remain distributed periodically.

[0025] For example, the processing performed on the workpiece to be measured by the circumferential surface measuring device may be any processing, such as cutting using a cutting tool, tiling processing using a tiling tool, scraping processing, laser processing, etc., so long as countless island-like convex or concave fine portions remain periodically distributed on the circumferential surface.

[0026] For example, the surface shape of the workpiece measured by the circumferential surface measuring device may be any one of surface properties, surface roughness, flatness, straightness, cylindricity, roundness, and the like.

[0027] For example, the measurement probe may be one that measures the surface shape of the workpiece by contacting the workpiece, or one that measures the surface shape of the workpiece in a non-contact manner.

[0028] For example, the measurement point moving means may be one that moves the measurement probe in a straight line parallel to the axis of the workpiece, or one that moves the workpiece in a straight line parallel to the axis of the workpiece, or one that moves the measurement probe and the workpiece in a straight line parallel to the axis of the workpiece.

[0029] For example, the rotation means may be one that rotates the workpiece around its axis, one that rotates the measurement probe around its axis, or one that rotates the workpiece and the measurement probe around its axis. EXAMPLES

[0030] Hereinafter, a circumferential surface measuring device and a circumferential surface measuring method using the circumferential surface measuring device according to one embodiment of the present invention will be described with reference to Figs. 1 to 4G.

[0031] <1. Shape of workpiece> First, a workpiece that is an object to be measured by a circumferential surface measuring device according to one embodiment of the present invention will be described with reference to FIGS. 1A to 1D. FIG. 1A is a perspective view of a workpiece to be cut, which is an object to be measured by a cutting circumference surface measuring device according to one embodiment of the present invention, FIG. 1B is a partially enlarged view of FIG. 1A, FIG. 1C is a line diagram of FIG. 1B, and FIG. 1D is a development view of FIG. 1B.

[0032] The workpiece, which is the object to be measured by the circumferential surface measuring device, is a round bar machined by low-frequency vibration cutting. Therefore, the circumferential surface measuring device according to one embodiment of the present invention can also be said to be a cut circumferential surface measuring device that measures the circumferential surface of a workpiece to be cut, which is a workpiece to be machined.

[0033] Low-frequency vibration cutting is a process in which at least one of the workpiece or the cutting tool is vibrated in the cutting direction while the rotation of the spindle that grips the workpiece is synchronized with the vibration in the cutting direction. When this type of low-frequency vibration cutting is performed on a workpiece W, the cutting tool passes through a cutting path CL as shown in Figures 1B and 1C, so that the circumferential surface of the machined portion of the workpiece W is left with countless convex fine portions T that look like islands, as well as periodically distributed concave portions V that are formed between the convex fine portions T by the passage of the cutting tool, as shown in Figures 1B, 1C, and 1D. In addition, in Figs. 1B and 1D, the white areas are high and the black areas are low.

[0034] <2. Overview of cutting circumference surface measuring device> Next, an overview of a cut circumferential surface measuring device 100, which is a circumferential surface measuring device, will be described with reference to FIG. FIG. 2 is a schematic perspective view of a cut circumferential surface measuring device according to one embodiment of the present invention.

[0035] The cutting circumference surface measuring device 100, which measures the surface shape of the workpiece W, comprises a base 110 with a horizontal surface that is placed on a floor surface F that is kept level, a workpiece holding member 120 that holds the workpiece W having a circular circumference surface, a measurement probe 130 that measures the surface shape of the workpiece W, a support arm 140 that supports the measurement probe 130, a probe moving mechanism (measurement point moving means) 150 that moves the measurement probe 130, and a controller 160.

[0036] The workpiece holding member 120 has a rectangular column-shaped base 121 placed on the base 110, a chuck 122 attached to the upper part of the base 121, and a motor (rotation means) 123 built into the base 121 for rotating the chuck 122. The chuck 122 extends horizontally and rotatably holds the workpiece W. Therefore, the axis Z of the workpiece W extends horizontally, and the workpiece W rotates around the axis Z.

[0037] The measurement probe 130 is a contact type probe that faces the circumferential surface of the workpiece W to be cut.

[0038] The support arm 140 is composed of an upright portion 141 extending vertically from the base 110 and a horizontal portion 142 extending horizontally from the upright portion 141 .

[0039] The probe moving mechanism 150 is attached to the horizontal portion 142 of the support arm 140 and is movable horizontally. Furthermore, the measurement probe 130 is attached to the probe movement mechanism 150 so that the tip of the measurement probe 130 faces vertically downward. Therefore, the measurement probe 130 can move linearly parallel to the axis Z of the workpiece W along the circumferential surface of the workpiece W.

[0040] The controller 160 has a drive control unit (drive control means) 161 that controls the motor 123 and the probe moving mechanism 150, a calculation unit 162 such as a CPU, and a memory unit 163 that stores the measurement results of the surface shape of the workpiece W by the measurement probe 130 and the calculation results by the calculation unit 162. The calculation unit 162 has a measurement direction specifying means 162a that specifies the measurement direction for the workpiece W.

[0041] Because the cut circumferential surface measuring device 100 is configured as described above, the cut circumferential surface measuring device 100 is able to measure the surface shape of the surface of the workpiece W not only in the longitudinal direction and circumferential direction, but also in the spiral direction.

[0042] <3.Measuring method for cut circumference surface> Next, a cut circumferential surface measuring method using the cut circumferential surface measuring device 100 will be described with reference to Figs. 3 to 4G.

[0043] <3.1. Identifying the measurement direction> First, the specification of the measurement direction performed in advance by the cut circumferential surface measuring device 100 will be described with reference to Figs. 3 to 4G. FIG. 3 is a flowchart showing the procedure for identifying the measurement direction, FIG. 4A is a diagram showing the result of imaging three-dimensional data of the surface shape of the workpiece, FIG. 4B is a diagram showing the convex fine features and feature direction in comparison with FIG. 4A, FIG. 4C is a diagram showing the measurement direction range for the first feature direction, FIG. 4D is a diagram showing the measurement direction range for the second feature direction, FIG. 4E is a diagram showing the measurement direction range for the third feature direction, FIG. 4F is a diagram showing the measurement direction range, and FIG. 4G is a diagram showing a method of identifying candidate measurement directions.

[0044] (Step S10) The cut circumferential surface measuring device 100 first reads three-dimensional data of the surface shape of the workpiece to be cut, which is the measurement target. This three-dimensional data is simulation data based on a machining simulation under the same conditions as the machining conditions for the workpiece to be measured, and includes at least three items: position in the feed direction (longitudinal direction of the workpiece), phase (rotation angle), and height. Figure 4A is an image of the 3D data of the surface shape of the workpiece being measured, with the horizontal axis representing the phase and the vertical axis representing the feed direction position, and the height is represented by different colors, with whiter points representing higher heights and blacker points representing lower heights.

[0045] (Step S11) Then, the calculation means 162 of the cut circumferential surface measuring device 100 extracts island-shaped convex fine portions T from the three-dimensional data read in step S10. Specifically, autocorrelation function and wavelet analysis are applied to the 3D data read in step S10, and binarization, numerical differentiation and digital filters are applied to the image data as shown in Figure 4A, which is the 3D data read in step S10 converted into image data, and image processing and image recognition techniques such as pattern recognition are applied to extract convex fine parts T that appear like countless islands as shown in Figure 4B. The convex fine portion T is an area including the apex as shown in FIG. 4B.

[0046] (Step S12) Then, the measurement direction specifying means 162a of the cut circumferential surface measuring device 100 selects one convex fine portion T1 from the image data processed in step S11, as shown in FIG. 4B. Next, the arrangement direction in which the convex fine portions T1 and T are connected to each other is identified as a characteristic direction by image recognition. In the case of three-dimensional data imaged as shown in FIG. 4A, the characteristic directions are, as shown in FIG. 4B, directions extending diagonally (d1, d4), a direction extending roughly parallel to the circumferential (phase) direction (d2), and a direction extending roughly parallel to the feed direction (d3).

[0047] (Step S13) Then, the measurement direction specifying means 162a of the cut circumferential surface measuring device 100 specifies a measurement direction range A including the measurement direction when performing the measurement, based on the characteristic direction specified in step S12. Since this measurement direction range is specified for each feature direction, it will be described below for each feature direction.

[0048] First, the determination of the measurement direction range for the feature direction d1 will be described with reference to FIG. 4C. The measurement direction determination means 162a of the cutting circumferential surface measuring device 100 extracts lines that are approximately parallel to the characteristic direction d1, i.e., a straight-line ridge line PL that connects the vicinity of the apex of the convex fine portion T and has the greatest unevenness in the height direction, and a straight-line valley line VL that is parallel to the ridge line PL and has the least unevenness in the height direction. When the ridge lines PL and valley lines VL are extracted as shown in Figure 4C, since the workpiece has been machined by low-frequency vibration cutting, countless convex fine portions T and the concave portions V formed between these convex fine portions T remain periodically distributed on the circumferential surface of the workpiece, and therefore the ridge lines PL and valley lines VL are arranged periodically on the circumferential surface of the workpiece. The measurement direction specifying means 162a of the cutting circumferential surface measuring device 100 determines, by image processing, the intersection p between a straight line X extending in the phase direction passing through a position a distance D away in the feed direction from the convex fine portion T1 shown in the central region of Figure 4C and a ridge line PL one period away from the characteristic direction d1. Next, the measurement direction determination means 162a of the cutting circumferential surface measuring device 100 determines the area outward from the line connecting the convex fine portion T1 and the intersection point p (i.e., the range where the ridge line PL and the valley line VL are arranged for one or more periods from the characteristic direction d1 at a position a distance D away from the convex fine portion T1 in the feed direction) as the measurement direction range A1 through image processing. In other words, "outside the line connecting the convex fine portion T1 and the intersection point p" means the range excluding the range where the ridge line PL and the valley line VL are arranged in less than one period from the characteristic direction d1 at a position away from the convex fine portion T1 in the feed direction by a distance D.

[0049] Next, measurement direction range A2 for feature direction d2, measurement direction range A3 for feature direction d3, and measurement direction range A4 for feature direction d4 are specified in the same manner as measurement direction range A1 for feature direction d1. Note that the determination of the measurement direction range A2 for the feature direction d2 is as shown in FIG. 4D, and the determination of the measurement direction range A3 for the feature direction d3 is as shown in FIG. 4E. The determination of the measurement direction range A4 for the feature direction d4 is similar to the determination of the measurement direction range for the feature direction d1, and is therefore not shown in the figures.

[0050] In the measurement direction ranges A1 to A4 for the feature directions d1 to d4 thus identified, the range where the measurement direction ranges for adjacent feature directions overlap (for example, the range where the measurement direction ranges A1 and A3 overlap) becomes the measurement direction range A for the convex fine portion T1 of the three-dimensional data read in step S10, as shown in Figure 4F. As shown in FIG. 4F, the measurement direction range A is formed to sandwich the characteristic directions d1 to d4.

[0051] (Step S14) Then, the measurement direction specifying means 162a of the cut circumferential surface measuring device 100 specifies one candidate measurement direction from each of the measurement direction ranges A. Specifically, as shown in FIG. 4G, first, a direction line M that passes through the convex fine portion T1 and is inside the measurement direction range A is set.

[0052] Next, a projection line N perpendicular to a direction line M passing through the apex of the convex fine portion T1 is set, and the apex of the convex fine portion T is projected onto this projection line N. In this case, the vertex of the convex fine portion T projected onto the projection line N is defined as a projection point i.

[0053] Next, if the n-th (n=1, 2, 3, . . . ) closest projection point to the convex fine portion T1 is tn and the distance between the projection point tn and the projection point tn+1 is δn, the measurement direction specifying means 162a of the cut circumferential surface measuring device 100 determines, for all n,

number

[0054] Then, the cut circumferential surface measuring device 100 specifies one measurement direction from the measurement directions specified in each measurement direction range A based on the measurement distance, etc.

[0055] The distance Ln between the projection point tn and the convex fine portion T1, which is necessary to calculate δn, can be calculated as follows. That is, as shown in FIG. 4G, when an orthogonal coordinate system is set with the horizontal axis (phase) as X and the vertical axis (feed direction) as Y, the coordinates of the convex fine part T1 are (x1, y1), the coordinates of the convex fine part Tn corresponding to the projection point tn are (xn, yn), the inclination angle of the direction line M with respect to the X axis is θ, and the projection line N is

number

number

number

[0056] <3.2. Surface shape measurement> Next, the measurement of the surface shape of the workpiece will be described. The cutting circumferential surface measuring device 100 measures the surface shape of the workpiece W to be cut by moving it from a measurement starting point selected by the user on the workpiece W to be measured in the measurement direction identified in step S14, passing through at least one concave portion V of the workpiece W and at least one convex fine portion T of the workpiece W. The number of scans by the measurement probe 130 from the measurement start point in the measurement direction is not limited to one, and may be multiple. Moreover, the measurement start point may be shifted slightly and the measurement probe 130 may be repeatedly scanned in the measurement direction, and the result may be used as the measurement result.

[0057] In this case, the inspection path satisfies equation (1) for all n; in other words, "when the distance between the inspection path extending from the convex fine portion T1 in the measurement direction and the apex of the convex fine portion T1 is arranged in ascending order, the distance between the apex of the nth (n = 1, 2, etc.) convex fine portion Tn and the inspection path is the next smallest after the distance between the apex of the n+1th convex fine portion Tn+1 and the inspection path, and the difference δn between the distance between the apex of the nth convex fine portion Tn and the inspection path and the distance between the apex of the n+1th convex fine portion Tn+1 and the inspection path is less than or equal to the predetermined interval value δc."

[0058] <4. Effects of the Cutting Circumferential Surface Measuring Device of the Present Invention> As described above, the cut circumferential surface measuring device 100, which is one embodiment of the present invention, is equipped with a measurement direction determining means 162a that determines the direction in which the arrangement period of the ridge lines PL and the valley lines VL exists for one or more periods as the measurement direction for the workpiece W, and a drive control unit 161 that is a drive control means that controls the motor 123, which is a rotation means, and the probe moving mechanism 150, which is a measurement point moving means, to move the measurement probe 130 from a predetermined measurement start point in the measurement direction so as to pass through at least one recess V of the workpiece W and at least one convex fine portion T of the workpiece W. Therefore, regardless of where the measurement start point is on the circumferential surface of the workpiece W, the measurement probe 130 will reliably pass through the convex fine portion T of the workpiece W. Therefore, regardless of where the measurement start point is on the circumferential surface of the workpiece W, the surface shape of the workpiece W on which countless convex fine portions T are periodically distributed can be accurately measured.

[0059] Furthermore, when the distance between the inspection path extending from the measurement starting point in the measurement direction and the apex of the convex fine portion T is arranged in ascending order, the distance between the apex of the nth (n = 1, 2, etc.) convex fine portion Tn and the inspection path is the next smallest after the distance between the apex of the n+1th convex fine portion Tn+1 and the inspection path, and the difference δn between the distance between the apex of the nth convex fine portion Tn and the inspection path and the distance between the apex of the n+1th convex fine portion Tn+1 and the inspection path is less than or equal to a predetermined interval value δ, so that the inspection path is more likely to pass near the convex fine portion T regardless of the measurement starting point, and the surface shape of the workpiece W in which countless convex fine portions T are periodically dispersed and left by low-frequency vibration cutting processing can be measured more accurately.

[0060] <5. Modifications> Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments.

[0061] For example, in this embodiment, the cut circumferential surface measuring device has only one measuring probe, but the number of measuring probes that the cut circumferential surface measuring device has is not limited to one, and the cut circumferential surface measuring device may have multiple measuring probes. Furthermore, since the cut circumference surface measuring device has multiple measurement probes, multiple points can be measured simultaneously, increasing the number of measurement points per unit time and enabling measurement data to be obtained at a higher density. In addition, if each of the measurement probes is independently movable, multiple measurement directions can be measured simultaneously. In addition, the multiple measurement probes may be configured using only one of a probe that contacts the workpiece to measure the surface shape of the workpiece and a probe that measures the surface shape of the workpiece without contacting the workpiece, or a probe that uses both. Furthermore, since the tip shapes and materials of multiple measurement probes can be different, it is possible to use in combination a measurement probe with a small tip radius used for roughness measurement, a measurement probe with a large tip radius used for waviness / shape measurement, and a measurement probe with a special tip shape suitable for special measurements, such as a disk shape, knife-edge shape, wedge shape, cylindrical shape, or curved hook shape.

[0062] For example, in this embodiment, the workpiece W is a solid round bar that has been subjected to low-frequency vibration cutting, but the workpiece W is not limited to this and may be, for example, a hollow round bar that has been subjected to low-frequency vibration cutting.

[0063] For example, in this embodiment, when identifying candidate measurement directions, simulation data based on a machining simulation was used, but candidate measurement directions may also be identified based on the results of scanning a measurement probe along the circumferential surface of the workpiece to be measured. In this case, since the measurement direction is specified in accordance with the workpiece to be actually measured, the surface shape of the workpiece can be measured more accurately. Also, a table that associates cutting conditions with measurement directions may be prepared in advance, and the measurement direction may be identified from the cutting conditions by referring to the table.

[0064] For example, in the circumferential surface measurement method of this embodiment, the measurement direction is determined by performing all of steps S10 to S14, but it is also possible to perform steps S10 to S13 to determine the measurement direction range, and then identify a direction that belongs to this measurement direction range as the measurement direction.

[0065] For example, in this embodiment, when determining the measurement direction range for each feature direction, point p was the intersection of a straight line X extending in the phase direction passing through a position distance D away in the feed direction from the convex fine portion T1 shown in the central region of Figure 4C and a ridge line PL one period away from the feature direction d1, but the position of point p may also be the intersection of a ridge line PL one period or more away from the feature direction d1 and the straight line X.

[0066] For example, in this embodiment, the cutting circumferential surface measuring device measures a cutting object on which countless convex fine portions and countless concave portions formed between these convex fine portions remain periodically distributed on the circumferential surface, and on which straight ridge lines connecting the vicinity of the apexes of the convex fine portions and having the greatest unevenness in the height direction and straight valley lines parallel to this ridge line and having the least unevenness in the height direction are periodically arranged on the circumference, but the measurement object is not limited to this. For example, a cut object having countless fine concave portions and countless fine convex portions formed between these fine concave portions periodically distributed on the circumferential surface, and having linear ridge lines connecting the vicinity of the apexes of the fine concave portions and having the greatest unevenness in the height direction and linear valley lines parallel to this ridge line and having the least unevenness in the height direction periodically arranged on the circumference, may be used as the workpiece to be measured by the cut circumferential surface measuring device. In this case, regardless of where the measurement starting point is on the circumferential surface of the workpiece, the measurement probe will reliably pass through the fine concave portions of the workpiece, so that regardless of where the measurement starting point is on the circumferential surface of the workpiece, the surface shape of the workpiece, on which countless fine concave portions are periodically distributed, can be accurately measured. [Explanation of symbols]

[0067] 100 ··· Cutting circumferential surface measuring device (circumferential surface measuring device) 110 Base 120... Cutting object holding member 121 ··· Base 122 ··· Chuck 123 Motor (rotating means) 130 Measuring probe 140 ··· Support arm 141 · · Upright part 142...Horizontal part 150 Probe moving mechanism (measurement point moving means) 160 ··· Controller 161 Drive control unit (drive control means) 162... Arithmetic section 162a... Measurement direction identification means 163... Storage section F...Floor surface Z: Axial center of the workpiece W ... Workpiece T... Convex minute part V... Concave minute part CL: Cutting path PL ··· Ridge line VL... valley line A: Measurement direction range M... direction line N... Projection line

Claims

1. A circumferential surface measuring device for measuring the surface shape of a workpiece on which a countless number of convex fine portions and a countless number of concave portions formed between the convex fine portions remain periodically distributed on the circumferential surface, and on which a linear ridge line that connects the vicinity of the apexes of the convex fine portions and has the greatest unevenness in the height direction and a linear valley line that is parallel to the ridge line and has the least unevenness in the height direction are periodically arranged on the circumference, a measurement probe for measuring a surface shape of the workpiece along a circumferential surface of the workpiece; a rotating means for rotating at least one of the workpiece and the measurement probe about an axis of the workpiece; a measurement point moving means for linearly moving at least one of the measurement probe and the workpiece parallel to an axis of the workpiece; a measurement direction specifying means for specifying a direction in which the arrangement period of the ridge lines and the valley lines exists at least once as a measurement direction for the workpiece; A circumferential surface measuring device comprising: a drive control means for controlling the rotating means and the measurement point moving means to move the measuring probe from a predetermined measurement starting point in the measurement direction so as to pass through at least one concave portion of the workpiece and at least one convex fine portion of the workpiece.

2. When the distances between the inspection path extending from the measurement start point in the measurement direction and the apex of the convex fine portion are arranged in ascending order, the distance between the apex of the n-th (n=1, 2, ...) convex fine portion and the inspection path is the second smallest after the distance between the apex of the n+1-th convex fine portion and the inspection path, 2. The circumferential surface measuring device according to claim 1, wherein the difference between the distance between the apex of the nth convex fine portion and the inspection path and the distance between the apex of the (n+1)th convex fine portion and the inspection path is less than or equal to a predetermined interval value.

3. 3. The circumferential surface measuring device according to claim 1, wherein the measurement direction specifying means specifies the measurement direction based on a result of scanning the measurement probe along the circumferential surface of the workpiece.

4. 4. The circumferential surface measuring device according to claim 1, wherein the workpiece is a workpiece cut by low-frequency vibration cutting.

5. 5. The circumferential surface measuring device according to claim 1, wherein a plurality of said measuring probes are provided.

6. A circumferential surface measuring device for measuring the surface shape of a workpiece in which a countless number of minute concave portions and a countless number of minute convex portions formed between the minute concave portions remain periodically distributed on the circumferential surface, and linear valley lines that connect the vicinity of the apexes of the minute concave portions and have the greatest unevenness in the height direction and linear ridge lines that are parallel to the valley lines and have the smallest unevenness in the height direction are periodically arranged on the circumference, a measurement probe for measuring a surface shape of the workpiece along a circumferential surface of the workpiece; a rotating means for rotating at least one of the workpiece and the measurement probe about an axis of the workpiece; a measurement point moving means for linearly moving at least one of the measurement probe and the workpiece parallel to an axis of the workpiece; a measurement direction specifying means for specifying a direction in which the arrangement period of the ridge lines and the valley lines exists at least once as a measurement direction for the workpiece; A circumferential surface measuring device comprising: a drive control means for controlling the rotation means and the measurement point moving means to move the measurement probe from a predetermined measurement starting point in the measurement direction so as to pass through at least one convex portion of the workpiece and at least one concave fine portion of the workpiece.

7. a measurement probe for measuring a surface shape of a workpiece along a circumferential surface of the workpiece on which an innumerable number of convex fine portions and an innumerable number of concave portions formed between the convex fine portions remain periodically distributed on the circumferential surface, and on which linear ridge lines connecting the vicinity of the apexes of the convex fine portions and having the greatest unevenness in the height direction and linear valley lines parallel to the ridge lines and having the smallest unevenness in the height direction are periodically arranged on the circumference; a rotation means for rotating at least one of the workpiece or the measurement probe about the axis of the workpiece; a measurement point moving means for linearly moving at least one of the measurement probe or the workpiece parallel to the axis of the workpiece; a measurement direction specifying means for specifying a direction in which the arrangement period of the ridge lines and the valley lines exists for one or more periods as a measurement direction for the workpiece; and a drive control means for controlling the rotation means and the measurement point moving means, a measurement direction specifying step in which the measurement direction specifying means specifies a direction in which the ridge line and the valley line exist for one or more periods as a measurement direction for the workpiece; and a measurement step in which the drive control means moves the measurement probe from a predetermined measurement starting point in the measurement direction so as to pass through at least one concave portion of the workpiece and at least one convex fine portion of the workpiece.

8. a measurement probe for measuring a surface shape of a workpiece along a circumferential surface of the workpiece on which an innumerable number of concave fine portions and an innumerable number of recesses formed between the concave fine portions remain periodically distributed on the circumferential surface, and on which linear valley lines connecting the vicinity of apexes of the concave fine portions and having the greatest unevenness in the height direction and linear ridge lines parallel to the valley lines and having the smallest unevenness in the height direction are periodically arranged on the circumference; a rotation means for rotating at least one of the workpiece or the measurement probe about the axis of the workpiece; a measurement point moving means for linearly moving at least one of the measurement probe or the workpiece parallel to the axis of the workpiece; a measurement direction specifying means for specifying a direction in which the arrangement period of the ridge lines and the valley lines exists for one or more periods as a measurement direction for the workpiece; and a drive control means for controlling the rotation means and the measurement point moving means, a measurement direction specifying step in which the measurement direction specifying means specifies a direction in which the ridge line and the valley line exist for one or more periods as a measurement direction for the workpiece; and a measurement step in which the drive control means moves the measurement probe from a predetermined measurement starting point in the measurement direction so as to pass through at least one convex portion of the workpiece and at least one concave fine portion of the workpiece.

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