JP7553052B2 - Cutting circumferential surface measuring device and cutting workpiece measuring method - Google Patents

Description

Article 30, paragraph 2 of the Patent Act applies (1) Publication name: Proceedings of the 2020 Japan Society for Precision Engineering Spring Meeting CD-ROM Publisher: Japan Society for Precision Engineering Publication date: March 1, 2020

The present invention relates to a cutting circumference surface measuring device and a cutting workpiece measuring method.

A conventional method for inspecting a cylinder is to detect irregularities 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 to scan the surface of the cylinder in a spiral manner in the axial direction (see, for example, Patent Document 1).

JP 2005-292539 A (particularly, claim 3)

When attempting to detect a workpiece that has multiple convex fine features periodically distributed on its circumferential surface due to low-frequency vibration cutting using the above-mentioned cylindrical body inspection method, 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.

The present invention solves the problems of the prior art as described above. In other words, the object of the present invention is to provide a cutting circumferential surface measuring device and a cutting workpiece measuring method that can accurately measure the surface shape of a cutting workpiece on which multiple convex fine parts remain distributed periodically.

First, the present invention is a cut circumferential surface measuring device that measures the surface shape of a workpiece that has been left with multiple convex fine parts periodically distributed on the circumferential surface by low-frequency vibration cutting, and is characterized by comprising a measurement probe that measures the surface shape of the workpiece along the circumferential surface of the workpiece, a workpiece rotation means that rotates at least one of the workpiece or the measurement probe around the axis of the workpiece, a measurement point moving means that moves at least one of the measurement probe or the workpiece linearly parallel to the axis of the workpiece, a measurement start point detection means that detects one of the convex fine parts of the workpiece as a measurement start point for the workpiece, a measurement direction specifying means that specifies the arrangement direction in which the convex fine parts of the workpiece are connected to each other as the measurement direction for the workpiece, and a drive control means that controls the workpiece rotation means and the measurement point moving means to move the measurement probe from the measurement start point to the measurement direction.

Secondly, the measurement start point detection means is characterized in that it scans a predetermined area of the circumferential surface of the workpiece with the measurement probe multiple times along different measurement paths to identify the convex fine portion of the workpiece.

Thirdly, the measurement direction determination means determines the measurement direction based on the results of scanning the measurement probe along the circumferential surface of the workpiece.

Fourthly, a measurement probe that measures the surface shape of a cut object along the circumferential surface of the cut object on which a plurality of convex fine parts are periodically distributed and left on the circumferential surface by low-frequency vibration cutting processing, a workpiece rotation means that rotates at least one of the workpiece or the measurement probe around the axis of the cut object, a measurement point movement means that linearly moves at least one of the measurement probe or the cut object parallel to the axis of the cut object, a measurement start point detection means that detects the measurement start point for the cut object, a measurement direction identification means that identifies the measurement direction for the cut object, the workpiece rotation means, and A method for measuring a cut object using a cutting circumferential surface measuring device that is equipped with a drive control means for controlling the measurement point moving means and measures the surface shape of the cut object, the method comprising a measurement direction specifying step in which the measurement direction specifying means specifies the arrangement direction in which the convex fine parts of the cut object are connected to each other as the measurement direction of the surface shape of the cut object, a measurement start point specifying step in which the measurement start point detection means detects one of the convex fine parts of the cut object as the measurement start point of the surface shape of the cut object, and a measurement step in which the drive control means moves the measurement probe from the measurement start point in the measurement direction.

The present invention can achieve the following effects.
(1) By comprising a measurement start point detection means for detecting one of the convex fine portions of the workpiece as the measurement start point for the workpiece, a measurement direction identification means for identifying the arrangement direction in which the convex fine portions of the workpiece are connected to each other as the measurement direction for the workpiece, and a drive control means for controlling the workpiece rotation means and the measurement point moving means to move the measurement probe from the measurement start point in the measurement direction, the measurement probe reliably passes through the convex fine portions of the workpiece, and the surface shape of the workpiece left with multiple convex fine portions periodically dispersed by low-frequency vibration cutting processing can be accurately measured.

(2) The measurement start point detection means scans a specified area on the circumferential surface of the workpiece with the measurement probe multiple times along different measurement paths to identify the convex fine part of the workpiece, and the convex fine part of the workpiece that serves as the measurement start point is identified by scanning the workpiece to be measured, allowing the surface shape of the workpiece to be measured more accurately.

(3) The measurement direction determination means determines the measurement direction based on the results of scanning the measurement probe along the circumferential surface of the workpiece, and therefore the measurement direction is determined in accordance with the workpiece actually being measured, making it possible to measure the surface shape of the workpiece more accurately.

(4) The method includes a measurement direction determination step in which the measurement direction determination means determines the arrangement direction in which the convex fine parts of the workpiece are connected to each other as the measurement direction of the surface shape of the workpiece, a measurement start point determination step in which the measurement start point detection means detects one of the convex fine parts of the workpiece as the measurement start point of the surface shape of the workpiece, and a measurement step in which the drive control means moves the measurement probe from the measurement start point in the measurement direction. This ensures that the measurement probe passes through the convex fine parts of the workpiece, and therefore makes it possible to accurately measure the surface shape of the workpiece in which multiple convex fine parts are periodically distributed and left by the low-frequency vibration cutting process.

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; FIG. 1B is a partially enlarged view of FIG. A diagrammatic representation of FIG. 1B. Exploded view of FIG. 1B. 1 is a schematic perspective view of a cutting circumferential surface measuring device according to an embodiment of the present invention; 11 is a flowchart showing a procedure for identifying a measurement direction. FIG. 13 is a diagram showing the result of imaging three-dimensional data of the surface shape of the workpiece. FIG. 4B is a diagram showing a state in which a convex fine portion is extracted from FIG. 4A . FIG. 4C is a diagram showing a state in which candidates for the measurement direction are identified with respect to FIG. 4B . 4 is a flowchart showing a procedure for measuring a surface shape. FIG. 4 is a diagram showing a measurement path of a measurement probe for identifying a measurement start point. FIG. 4 is a diagram showing the measurement results of a measurement probe. FIG. 4 is a diagram showing the measurement direction of a measurement probe.

The present invention is a cutting circumferential surface measuring device that measures the surface shape of a workpiece in which multiple convex fine parts are periodically distributed on the circumferential surface by low-frequency vibration cutting, and includes a measurement probe that measures the surface shape of the workpiece along the circumferential surface of the workpiece, a workpiece rotation means that rotates at least one of the workpiece or the measurement probe around the axis of the workpiece, a measurement point moving means that moves at least one of the measurement probe or the workpiece linearly parallel to the axis of the workpiece, a measurement start point detection means that detects one of the convex fine parts of the workpiece as the measurement start point for the workpiece, a measurement direction specifying means that specifies the arrangement direction in which the convex fine parts of the workpiece are connected to each other as the measurement direction for the workpiece, and a drive control means that controls the workpiece rotation means and the measurement point moving means to move the measurement probe from the measurement start point in the measurement direction, and the specific embodiment may be any as long as it accurately measures the surface shape of a workpiece in which multiple convex fine parts are periodically distributed and remain.

For example, if there are at least two or more convex fine portions remaining on the circumferential surface of the workpiece to be measured by the cut circumferential surface measuring device, the surface shape of the workpiece can be measured by the cut circumferential surface measuring device. However, if an infinite number of convex fine portions remain on the circumferential surface of the workpiece (to the point where they cannot be counted), the cut circumferential surface measuring device can identify the measurement direction based on the many convex fine portions, and the surface shape of the workpiece can be accurately measured by the cut circumferential surface measuring device.

For example, the workpiece measured by the cutting circumferential surface measuring device may be of any shape, such as a cylindrical workpiece, a cylindrical workpiece, a conical workpiece, or a truncated cone-shaped workpiece, as long as it has a circumferential surface.

For example, the surface shape of the workpiece measured by the cutting circumferential surface measuring device may be anything, such as surface properties, surface roughness, flatness, straightness, cylindricity, roundness, etc.

For example, the measurement probe may be one that contacts the workpiece to measure the surface shape of the workpiece, or one that measures the surface shape of the workpiece without contact.

For example, the measurement point moving means may be one that moves the measurement probe linearly parallel to the axis of the workpiece, or one that moves the workpiece linearly parallel to the axis of the workpiece, or one that moves the measurement probe and the workpiece linearly parallel to the axis of the workpiece.

For example, the rotating means may rotate the workpiece around its axis, may rotate the measuring probe around its axis, or may rotate the workpiece and the measuring probe around its axis.

The following describes an embodiment of the cut circumferential surface measuring device and a cut circumferential surface measuring method using the cut circumferential surface measuring device, based on Figures 1 to 6D.

<1. Shape of the workpiece>
First, a workpiece to be cut, which is an object to be measured by a cut 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 circumferential 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.

The workpiece W, which is the object to be measured by the cutting circumferential surface measuring device, is a round bar machined using low-frequency vibration cutting.

Here, 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 such low-frequency vibration cutting is performed on a workpiece W, the cutting tool passes through a cutting path L 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 shown in Figures 1B, 1C, and 1D, and recesses V that are formed between the convex fine portions T by the passage of the cutting tool, which are periodically distributed.
In addition, in Figs. 1B and 1D, the white parts are high in height, and the black parts are low in height.

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

The cutting circumferential surface measuring device 100 for measuring the surface shape of the workpiece W includes a base 110 with a horizontal surface that is placed on a floor surface F that is kept level, a workpiece holding member 120 for holding the workpiece W having a circumferential surface, a measuring probe 130 for measuring the surface shape of the workpiece W, a support arm 140 for supporting the measuring probe 130, a probe movement mechanism (measurement point movement means) 150 for moving the measuring probe 130, and a controller 160.

The workpiece holding member 120 has a rectangular columnar base 121 placed on the base 110, a chuck 122 attached to the upper part of the base 121, and a motor (workpiece rotation means) 123 built into the base 121 and rotating the chuck 122.
The chuck 122 extends horizontally and rotatably holds the workpiece W.
Therefore, the axis Z of the workpiece W extends in the horizontal direction, and the workpiece W rotates around the axis Z.

The measurement probe 130 is a contact type probe that faces the circumferential surface of the workpiece W.

The support arm 140 is composed of an upright portion 141 that extends vertically from the base 110, and a horizontal portion 142 that extends horizontally from the upright portion 141.

The probe moving mechanism 150 is attached to the horizontal portion 142 of the support arm 140 and is movable in the horizontal direction.
Furthermore, the measurement probe 130 is attached to the probe moving 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.

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, and a measurement start point detecting means 162b that detects the measurement start point for the workpiece W.

Because the cutting circumferential surface measuring device 100 is configured as described above, the cutting circumferential surface measuring device 100 is capable of measuring the surface shape of the surface of the workpiece W not only in the longitudinal and circumferential directions, but also in the spiral direction.

<3. Cutting Circumferential Surface Measurement Method>
Next, a method for measuring a cut circumferential surface using the cut circumferential surface measuring device 100 will be described with reference to FIGS. 3 to 6C.

<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 4C.
Figure 3 is a flowchart showing the procedure for identifying the measurement direction, Figure 4A is a diagram showing the result of imaging three-dimensional data of the surface shape of the workpiece, Figure 4B is a diagram showing the state in which convex fine parts have been extracted from Figure 4A, and Figure 4C is a diagram showing the state in which candidate measurement directions have been identified from Figure 4B.

(Step S10)
The cut circumferential surface measuring device 100 first reads three-dimensional data of the surface shape of the workpiece to be measured.
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.
FIG. 4A is an image of the three-dimensional data of the surface shape of the workpiece to be measured, in which the horizontal axis represents the phase and the vertical axis represents the feed direction position, and height is represented by different colors, with whiter points representing higher heights and blacker points representing lower heights.

(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, an autocorrelation function or wavelet analysis is applied to the three-dimensional data read in step S10, and the three-dimensional data read in step S10 is converted into image data as shown in FIG. 4A, and then binarization, numerical differentiation, or a digital filter is applied to the image data, wavelet analysis is performed, or image processing techniques and image recognition techniques such as pattern recognition are applied to extract convex fine parts T that appear like countless islands as shown in FIG. 4B.
As shown in FIG. 4B, the convex fine portion T is an area including a region of the apex.

(Step S12)
Then, the measurement direction identifying means 162a of the cut circumferential surface measuring device 100 identifies the arrangement directions d1 to d4 in which the convex fine portions T of the cut workpiece are connected to each other as candidate measurement directions for the cut workpiece through image recognition from the image data processed in step S11.

Specifically, for three-dimensional data imaged as shown in FIG. 4A, the possible measurement directions are a direction (d1) extending roughly parallel to the feed direction, diagonal directions (d2, d4), and a direction (d3) extending roughly parallel to the circumferential (phase) direction, as shown in FIG. 4C.

<3.2. Measurement of surface shape>
Next, measurement of the surface shape of the workpiece will be described with reference to Figs. 5 to 6C.
FIG. 5 is a flowchart showing the procedure for measuring the surface shape, FIG. 6A is a diagram showing the measurement path of the measurement probe for identifying the measurement starting point, FIG. 6B is a diagram showing the measurement results of the measurement probe, and FIG. 6C is a diagram showing the measurement direction of the measurement probe.

(Step S20)
First, the drive control unit 161 of the cut circumferential surface measuring device 100 controls at least one of the motor 123 or the probe moving mechanism 150 to scan a predetermined measurement start point search area A of the circumferential surface of the workpiece W with the measurement probe 130 multiple times along different measurement paths S, as shown in Figure 6A.

(Step S21)
Then, the measurement start point detection means 162b of the cut circumferential surface measuring device 100 identifies the highest point (near the apex of the convex fine portion T of the workpiece W) as the measurement start point P from the measurement results by the measuring probe 130 as shown in Figure 6B.

(Step S22)
Then, the direction set by the user from among the candidate measurement directions (d1, d2, d3, d4) identified in step S12 is used as the measurement direction, and scanning is performed with the measurement probe 130 from the measurement starting point P to measure the surface shape of the workpiece W.
The number of scans by the measurement probe 130 from the measurement start point P in the measurement direction is not limited to one, but may be multiple.
Moreover, the measurement start point P 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.

In addition, based on the measurement results of the surface shape of the workpiece W when the d1 direction is selected as the measurement direction, it is possible to confirm whether the feed conditions in the low-frequency vibration cutting process are appropriate.
Furthermore, based on the measurement results of the surface shape of the workpiece W when the d2 direction, d3 direction, and d4 direction are selected as the measurement directions, it is possible to confirm whether the vibration conditions for low-frequency vibration cutting are appropriate.

4. Effects of the Cutting Circumferential Surface Measuring Device of the Present Embodiment
As described above, according to the cutting circumferential surface measuring device 100 which is one embodiment of the present invention, it is equipped with a measurement start point detection means 162b which detects one of the convex fine portions T of the workpiece W as the measurement start point P for the workpiece, a measurement direction identification means 162a which identifies the direction in which the convex fine portions T of the workpiece W are periodically connected as the measurement direction for the workpiece, and a drive control unit 161 which is a drive control means which controls the motor 123 which is the workpiece rotation means and the probe moving mechanism 150 which is the measurement point moving means to move the measurement probe 130 from the measurement start point P in the measurement direction, so that the measurement probe 130 reliably passes through the convex fine portions T of the workpiece W, and therefore it is possible to accurately measure the surface shape of the workpiece W in which countless convex fine portions T are periodically dispersed and left by the low-frequency vibration cutting process.
Furthermore, when comparing the measurement results of the surface shape of the workpiece W with the simulation data, it is possible to check for discrepancies or differences in the spacing of the convex fine features, thereby detecting the presence or absence of a phase shift or synchronization shift between the rotation speed of the spindle of the machine tool and the vibration frequency of the cutting tool, and estimating the amount of discrepancy.

In addition, the measurement start point detection means 162b scans a predetermined measurement start point search area A on the circumferential surface of the workpiece W with the measurement probe 130 multiple times along different measurement paths S to identify the convex fine part T of the workpiece W, and the convex fine part T of the workpiece W that is the measurement start point P is identified by scanning the workpiece W to be measured, so that the surface shape of the workpiece W can be measured more accurately.

5. Modifications
Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments.

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 measurement probes with a small tip radius for roughness measurement, measurement probes with a large tip radius for waviness/shape measurement, and measurement probes with special tip shapes suitable for special measurements such as disk-shaped, knife-edge-shaped, wedge-shaped, cylindrical, or hook-shaped with a curved tip.

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.

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.

For example, in step S20 of this embodiment, the measurement path S is a path in which only the phase is changed while the Z feed direction position is kept constant (horizontal direction in FIG. 6A), but the measurement path S is not limited to this, and may be a path in which the Z feed position is changed while the phase is kept constant within the measurement start point search area A (vertical direction in FIG. 6A), or a path in which both the measurement path S and the phase are changed (diagonal direction in FIG. 6A).

100: Cutting circumferential surface measuring device 110: Base 120: Cutting object holding member 121: Base 122: Chuck 123: Motor (cutting object rotating means)
130: Measuring probe 140: Support arm 141: Upright portion 142: Horizontal portion 150: Probe moving mechanism (measurement point moving means)
160: Controller 161: Drive control unit (drive control means)
162: Calculation section 162a: Measurement direction specification means 162b: Measurement start point detection means 163: Storage section

F: Floor surface Z: Axis of the workpiece

W: Workpiece T: Convex fine part V: Concave part P: Measurement start point L: Cutting path S: Measurement path A: Measurement start point search area

Claims (4)

A cutting circumferential surface measuring device for measuring the surface shape of a cutting workpiece having a plurality of convex fine portions periodically distributed and remaining on the circumferential surface,
a measurement probe for measuring a surface shape of the workpiece along a circumferential surface of the workpiece;
a workpiece rotating means for rotating at least one of the workpiece or the measurement probe around 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 start point detection means for detecting one of the convex fine portions of the workpiece as a measurement start point for the workpiece;
A measurement direction specifying means for specifying an arrangement direction in which the convex fine portions of the workpiece are connected to each other as a measurement direction for the workpiece;
a drive control means for controlling the workpiece rotating means and the measurement point moving means to move the measurement probe from the measurement start point in the measurement direction, The cutting circumferential surface measuring device according to claim 1, wherein the measurement start point detection means scans a predetermined area of the circumferential surface of the workpiece with the measurement probe multiple times along different measurement paths to identify the convex fine portion of the workpiece. The cutting circumferential surface measuring device according to claim 1 or 2, wherein 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. A cutting workpiece measuring method using a cutting circumferential surface measuring device that includes a measuring probe that measures a surface shape of a cutting workpiece along a circumferential surface of the cutting workpiece on which a plurality of convex fine portions are periodically distributed and left on the circumferential surface by low-frequency vibration cutting, a cutting workpiece rotating means that rotates at least one of the cutting workpiece or the measuring probe around the axis of the cutting workpiece, a measuring point moving means that moves at least one of the measuring probe or the cutting workpiece linearly parallel to the axis of the cutting workpiece, a measuring start point detecting means that detects the measuring start point for the cutting workpiece, a measuring direction specifying means that specifies the measuring direction for the cutting workpiece, and a drive control means that controls the cutting workpiece rotating means and the measuring point moving means,
a measurement direction specifying step in which the measurement direction specifying means specifies an arrangement direction in which the convex fine portions of the workpiece are connected to each other as a measurement direction of the surface shape of the workpiece;
a measurement start point specifying step in which the measurement start point detecting means detects one of the convex fine portions of the workpiece as a measurement start point of the surface shape of the workpiece;
and a measuring step in which the drive control means moves the measuring probe from the measurement start point in the measurement direction.