JP5789010B2 - Surface shape measuring device and machine tool provided with the same - Google Patents

Description

  The present invention relates to a surface shape measuring device that measures a surface shape by a non-contact type displacement sensor using a light beam, and a machine tool including the surface shape measuring device.

  Conventionally, when machining with a machine tool, it is common to measure the shape of the workpiece with a non-contact sensor. In this case, the machining program for the machine tool is created using an interactive system or an external computer based on the measured shape.

  When the shape of the workpiece is measured by a non-contact sensor, the surface step (also referred to as “edge”) of the workpiece is an important part in setting the machining start point. This is because how accurately and quickly the edge is detected affects the machining accuracy and the machining time.

  Several methods for accurately detecting an edge using a non-contact sensor have been proposed. For example, in the technique described in Japanese Patent Application Laid-Open No. 2012-194085 (Patent Document 1), a laser beam from a semiconductor laser is condensed and irradiated on a surface to be measured, and the reflected light is condensed on a multi-split photodetector. . In order to focus the laser beam on the measurement surface, the distance between the laser beam and the measurement surface is adjusted so that a plurality of output signals from the photodetector have the maximum amplitude. The edge of the measurement surface is detected from the output intensity difference of each detector that constitutes the multi-split photodetector.

JP 2012-194085 A

  In the above prior art, it is necessary to focus the reflected light of the laser beam on the multi-divided photodetector, so that the apparatus configuration is complicated. Furthermore, since it is necessary to adjust the laser light source and the optical system so that the laser beam is focused on the measurement surface in order to detect the position of the edge, it takes time for measurement.

  The present invention has been made in consideration of the above-described problems, and an object of the present invention is to provide a surface shape measuring device capable of detecting the position of the surface step of the measurement object in a shorter time than in the prior art. Is to provide.

  In one aspect, the present invention is a surface shape measuring apparatus that measures a surface shape of a measurement object including a step, and includes a displacement meter, a moving mechanism, a measurement control unit, and a step specifying unit. The displacement meter includes a light emitting unit that emits a light beam toward the measurement target, an optical system that collects scattered light of the light beam from the measurement target, and a light receiving unit that detects a light collection position by the optical system. The displacement meter measures the displacement of the surface of the measurement object based on the light collection position at the light receiving unit. The moving mechanism scans the light beam by relatively moving the displacement meter and the measurement object. The measurement control unit is configured to execute a first measurement step and a second measurement step. In the first measurement step, the measurement control unit continuously measures the displacement of the surface of the measurement object with the displacement meter while scanning the light beam with the moving mechanism in the direction intersecting the step. In the second measurement step, the measurement control unit performs the first measurement in a state where the arrangement of the optical system and the light receiving unit is rotated by 180 degrees with respect to the case of the first measurement step with the light beam as the rotational symmetry axis. The same location as the step is continuously measured with a displacement meter. The step identifying unit identifies the position of the step based on the separation start point at which the measurement value from the first measurement step and the measurement value from the second measurement step start to separate.

  According to said structure, a difference arises in the measured value of the level | step-difference part in a 1st measurement step, and the measured value of a level | step-difference part in a 2nd measurement step. Therefore, the position of the step can be specified based on the position of the measurement point (separation start point) where the difference between the measurement values starts to occur.

  Preferably, the step identifying unit is separated from the separation start point by ½ of the spot size of the light beam in a section where the measurement value from the first measurement step and the measurement value from the second measurement step are separated. The point is specified as the position of the step.

  Preferably, the surface shape measuring apparatus further includes a data correction unit. The data correction unit converts the displacement value of the surface at each measurement point from the separation start point to the specified step position into an average value of the measurement value by the first measurement step and the measurement value by the second measurement step. Set.

  Preferably, when viewed in plan from the direction along the light beam, the scanning direction of the light beam is not perpendicular to the optical path surface including the light beam and the light collection position of the light receiving unit.

  Preferably, in the first measurement step, the light receiving unit is disposed either forward or backward in the scanning direction of the light beam with respect to the light beam. In the second measurement step, the light receiving portions are arranged on the other of the front and rear in the scanning direction with respect to the light beam.

  In another aspect, the present invention provides a surface shape measuring apparatus for measuring the surface shape of a measurement object including a step, a displacement meter that continuously measures the displacement of the surface of the measurement object, a moving mechanism, and a measurement A control part and a level | step difference specific part are provided. The displacement meter includes a light emitting unit that emits a light beam toward the measurement target, first and second optical systems that collect scattered light of the light beam from the measurement target, and first and second optics. And first and second light receiving portions for detecting the light collection positions by the system. The second optical system and the second light receiving unit are arranged at positions obtained by rotating the first optical system and the first light receiving unit by 180 degrees with the light beam as the rotational symmetry axis. The displacement meter measures the displacement of the surface of the measurement object based on the respective condensing positions of the first and second light receiving units. The moving mechanism scans the light beam by relatively moving the displacement meter and the measurement object. The measurement control unit is configured to continuously measure the displacement of the surface of the measurement object with a displacement meter while scanning the light beam with a moving mechanism in a direction crossing the step. The step identifying unit identifies the position of the step based on the separation start point at which the measurement value from the first light receiving unit and the measurement value from the second measurement step start to separate.

  According to said structure, a difference arises in the measured value of the level | step-difference part by a 1st light-receiving part, and the measured value of the level | step-difference part by a 2nd light-receiving part. Therefore, the position of the step can be specified based on the position of the measurement point (separation start point) where the difference between the measurement values starts to occur.

  In still another aspect, the present invention is a machine tool including the above surface shape measuring device.

  Therefore, according to the present invention, it is possible to detect the position of the surface step of the measurement object in a simpler and shorter time than in the past.

It is a figure which shows typically the structure of a laser displacement meter. It is a perspective view which shows typically the structure of the linear image sensor of FIG. It is a figure which shows an example of the data detected by the linear image sensor of FIG. 1 is a block diagram schematically showing a configuration example of a surface shape measuring apparatus according to Embodiment 1. FIG. It is a figure for demonstrating the error which arises at the time of the measurement of a level | step-difference part. It is a figure for demonstrating the error which arises at the time of the measurement of a level | step-difference part, when arrangement | positioning of the laser displacement meter shown in FIG. 5 is rotated 180 degree | times. It is a figure which shows typically an example of the luminance distribution of the condensing spot on a linear image sensor in the case of FIG. 5 and FIG. In the case of FIG. 5 and FIG. 6, it is a figure which shows an example of the measurement data of surface shape. It is a flowchart which shows the measurement procedure of a surface shape, and the processing procedure of the measured data. It is a figure which shows typically the structure of the laser displacement meter used with the surface shape measuring apparatus by Embodiment 2. FIG. 10 is a flowchart showing a procedure for measuring a surface shape and a processing procedure for measured data in the apparatus according to the second embodiment. FIG. 10 is a perspective view schematically showing a configuration of a machine tool according to a third embodiment. It is a block diagram which shows the functional structure of the part regarding the surface shape measuring apparatus among the machine tools of FIG.

  Hereinafter, each embodiment will be described in detail with reference to the drawings. In the following embodiments, a surface shape measuring device using a laser displacement meter will be described as an example. However, in the case of a non-contact displacement meter using a non-coherent light beam instead of a laser beam, The present invention can be applied. In the following description, the same or corresponding parts are denoted by the same reference symbols, and the description thereof may not be repeated.

<Embodiment 1>
[Outline of laser displacement meter]
FIG. 1 is a diagram schematically showing a configuration of a laser displacement meter. Referring to FIG. 1, laser displacement meter 100 includes a light emitting unit 110, a condensing lens 118 as an optical system, and a linear image sensor 120 as a light receiving unit. The light emitting unit 110 includes a laser diode 112 and a lens 114.

  The laser beam 116 emitted from the laser diode 112 is shaped into substantially parallel light by the lens 114 and is irradiated onto the measurement object 130. The spot size w (also referred to as spot diameter) of the laser beam 116 on the measurement object is, for example, 50 μm in diameter.

The light diffusely reflected on the measurement object 130 is collected by the condenser lens 118 on the linear image sensor 120 arranged in the angle direction of the laser beam 116 and γ. In FIG. 1, the focal length of the condenser lens 118 is f _0, and the distance from the irradiation position (laser spot 132) of the laser beam 116 on the surface of the measurement object 130 to the condenser lens 118 is l.

  The linear image sensor 120 is disposed at an angle based on a Scheimpflug Condition. That is, the detection surface of the linear image sensor 120 and the main surface of the condenser lens 118 intersect with each other in a straight line, and the angle formed by these surfaces is β. A surface including the laser beam 116 is a subject surface. With this arrangement, even if the distance between the measurement object 130 and the laser displacement meter 100 changes, the laser spot 132 is imaged on the linear image sensor 120 without being blurred.

  In FIG. 1, the direction of the laser beam 116 is taken as the Z-axis direction. A surface including the central axis of the laser beam 116 and the optical axis of the condenser lens 118 is referred to as an optical path surface. A direction parallel to the optical path surface and perpendicular to the Z-axis direction is taken as an X-axis direction. A direction perpendicular to both the X-axis direction and the Z-axis direction is taken as a Y-axis direction. In the case of FIG. 1, the Y-axis direction is a direction perpendicular to the paper surface, and the XZ plane is parallel to the paper surface (optical path surface).

  Here, the beam size of laser light (spot size on the measurement object) will be described. There are various definitions of the beam size of laser light. For example, in the case of a laser beam having a symmetric beam profile as in the TEM00 mode, in a plane orthogonal to the optical axis, 1 / e 2 of the peak value (where e is the base of natural logarithm) ( The beam size is defined by the width of the intensity distribution (13.5%). When the beam profile is broken, for example, a circle including 86.5% of the total beam power is included on the basis of the peak power, and the diameter of this circle is defined as the beam size. In this specification, in order to include various definitions, the range of the beam size (measurement object) from the diameter of the circle including 50% of the total power to the diameter of the circle including 95% of the total power is substantially exceeded. Equal to the spot size above).

  FIG. 2 is a perspective view schematically showing the configuration of the linear image sensor of FIG. Referring to FIG. 2, the linear image sensor 120 includes 1024 pixels 122 arranged in a straight line. Each pixel 122 outputs a signal with a luminance level from 0 to a maximum of 255 according to the amount of received light.

  FIG. 3 is a diagram illustrating an example of data detected by the linear image sensor of FIG. The horizontal axis in FIG. 3 indicates the pixel position, and the vertical axis indicates the luminance level. Referring to FIGS. 2 and 3, the light diffusely reflected on the measurement object 130 is condensed by the condenser lens 118 onto the spot 124 on the linear image sensor 120, whereby a Gaussian as shown in FIG. Distributed data is obtained. The distance from the center of gravity of the data in FIG. 3 to the object is calculated by triangulation. In the case of FIG. 3, the center line 180 of the luminance distribution coincides with the center of gravity.

[Configuration of surface shape measuring device]
FIG. 4 is a block diagram schematically showing a configuration example of the surface shape measuring apparatus according to the first embodiment. Referring to FIG. 4, surface shape measurement apparatus 140 includes table 144 on which measurement object 130 is placed, saddle 142, laser displacement meter 100, X-axis drive mechanism 146 </ b> X, and Y-axis drive mechanism 146 </ b> Y. , A Z-axis drive mechanism 146Z, a C-axis drive mechanism 146C, and a computer 150.

  The table 144 is disposed on the saddle 142 and is movable in the X-axis direction. The saddle 142 is movable in the Y axis direction. The X-axis drive mechanism 146X moves the table 144 in the X-axis direction. The Y-axis drive mechanism 146Y moves the saddle 142 in the Y-axis direction. The Z-axis drive mechanism 146Z moves the laser displacement meter 100 in the Z-axis direction. The C-axis drive mechanism 146C rotates the laser displacement meter 100 about a rotation axis (C-axis rotation center) parallel to the Z-axis. The C-axis drive mechanism 146C can be set to an arbitrary rotation angle with respect to the reference position.

  The X-axis drive mechanism 146X, the Y-axis drive mechanism 146Y, the Z-axis drive mechanism 146Z, and the C-axis drive mechanism 146C function as a moving mechanism 146 for relatively moving the laser displacement meter 100 and the measurement object 130. . Therefore, the laser beam 116 scans the surface of the measurement object 130 by the moving mechanism 146.

  The configuration of the moving mechanism 146 is not limited to the example of FIG. For example, the measurement object 130 may be fixed and the laser displacement meter 100 may be movable in three directions of X, Y, and Z. The laser displacement meter 100 may be fixed, and the table 144 that supports the measurement object 130 may be configured to be rotatable around the C-axis rotation center.

  The computer 150 includes a processor 152, a memory 154, a display device and an input / output device (not shown), and the like. The processor 152 functions as a measurement control unit 156 and a data processing unit 158 by executing a program stored in the memory 154.

  The measurement control unit 156 scans the laser beam 116 by controlling the laser displacement meter 100 and the moving mechanism 146. During the scanning of the laser beam 116, the measurement control unit 156 continuously measures the surface shape data 166 of the measurement object 130 using the laser displacement meter 100. The measured surface shape data 166 is stored in the memory 154. The surface shape data 166 is a data series in which a scanning position on the measurement object 130 (position where the laser beam is irradiated) and a displacement in the Z-axis direction of the surface of the measurement object 130 at the scanning position are associated with each other. is there.

  The measurement control unit 156 further controls the C-axis drive mechanism 146C to rotate the laser displacement meter 100 180 degrees around a rotation axis (C-axis rotation center) parallel to the Z-axis direction. As a result, when the C-axis rotation center and the center axis of the laser beam 116 coincide with each other, the laser displacement meter 100 rotates 180 degrees around the center axis of the laser beam 116. That is, the condenser lens 118 (optical system) and the linear image sensor 120 (light receiving unit) in FIG. 1 move to positions that are line-symmetric with respect to the central axis of the laser beam 116. When the center axis of the laser beam 116 and the C-axis rotation center do not coincide with each other, the laser displacement meter 100 is moved in the X-axis direction and the Y-axis direction along with the rotation around the C-axis rotation center, whereby the laser beam The laser displacement meter 100 can be rotated 180 degrees around the central axis of the laser beam 116 while maintaining the position 116.

  As will be described later, the measurement control unit 156 measures, after the laser displacement meter 100 is rotated 180 degrees around the central axis of the laser beam 116, the same portion as before the rotation is measured by the laser displacement meter 100. By comparing the surface shape data of the same location measured before and after the rotation, the edge position of the stepped portion of the measuring object 130 can be detected easily, accurately and in a short time.

  The data processing unit 158 performs data processing on the data (surface shape data 166) measured by the laser displacement meter 100 in order to specify the step position. The contents of the data processing will be described later with reference to FIG.

  Next, a specific method for detecting the step position will be described. In the apparatus according to the present embodiment, the step position is detected by using an error generated when the step portion is measured by a triangulation laser displacement meter. In the following, first, errors that occur during measurement of the stepped portion will be described, and then a data processing procedure for detecting the stepped position will be described.

[Errors that occur when measuring stepped parts]
FIG. 5 is a diagram for explaining an error that occurs during measurement of a stepped portion. In FIG. 5, the scanning direction of the laser beam is the + X direction. A laser beam is irradiated along a straight line 136 on the surface of the measurement object 130. The direction of the straight line 136 (scanning direction of the laser beam) intersects the edge 134 of the stepped portion (it does not need to be orthogonal). In FIG. 5, the size of the laser spot 132 is shown in an enlarged manner for easy illustration.

  In the example shown in FIG. 5, the condensing lens (optical system) 118 and the linear image sensor (light receiving unit) 120 constituting the laser displacement meter are arranged in front of the laser beam in the scanning direction. The direction is determined. In this case, when the laser spot 132 reaches the edge portion, a part of the laser spot 132 on the side close to the linear image sensor 120 is missing. As a result, the position of the center of gravity of the condensing spot 124 of the linear image sensor 120 moves, so that the surface flat portion 138 of the measurement target 130 is positioned above the actual position by ε + (closer to the light emitting unit 110). Observed at.

  FIG. 6 is a diagram for explaining an error that occurs during measurement of a step portion when the arrangement of the laser displacement meter shown in FIG. 5 is rotated by 180 degrees. Similarly to the case of FIG. 5, the scanning direction of the laser beam is the + X direction, and the laser beam is irradiated along a straight line 136 that is the same location on the surface of the measurement object 130. For ease of illustration, the size of the laser spot 132 is shown enlarged.

  The arrangement of the condensing lens 118 and the linear image sensor 120 in the case of FIG. 6 is obtained by rotating the arrangement in the case of FIG. 5 by 180 degrees around the center axis 116C of the laser beam. In other words, the orientation of the laser displacement meter is determined so that the condenser lens 118 and the linear image sensor 120 are located behind the laser beam in the scanning direction. In this case, when the laser spot 132 reaches the edge, a part of the laser spot 132 on the side far from the linear image sensor 120 is missing. As a result, the gravity center position of the condensing spot 124 of the linear image sensor 120 moves. However, the moving direction of the center of gravity of the condensing spot 124 is opposite to that in FIG. Therefore, the surface of the measurement object 130 is observed so as to be positioned lower by ε− than the actual object (distant from the light emitting unit 110).

  FIG. 7 is a diagram schematically illustrating an example of the luminance distribution of the focused spot on the linear image sensor in the case of FIGS. 5 and 6. FIG. 7A shows the luminance distribution in the case corresponding to FIG. 5, and FIG. 7B shows the luminance distribution in the case corresponding to FIG. When the laser beam is irradiated on a flat surface, the luminance distribution has a shape close to a Gaussian distribution, and the center line 180 of the luminance distribution in this case is indicated by a one-dot chain line. As shown in the figure, the barycentric position 182 of the luminance distribution in the case of FIG. 7A corresponding to FIG. 5 and the barycentric position 184 of the luminance distribution in FIG. 7B corresponding to FIG. The lines 180 are offset in opposite directions. As a result, the measured value of the laser displacement meter has an error in the opposite direction between the case of FIG. 5 and the case of FIG.

  FIG. 8 is a diagram illustrating an example of surface shape measurement data in the cases of FIGS. 5 and 6. 8A, the measurement data 186 in the case of FIG. 5 is indicated by a solid line, and the measurement data 188 in the case of FIG. 6 is indicated by a broken line. 8B shows an average value 190 of the measurement data 186 in the case of FIG. 5 and the measurement data 188 in the case of FIG.

  Referring to FIG. 8A, in the region on the left side from point P0, measurement data 186 in the case of FIG. 5 and measurement data 188 in the case of FIG. In the region on the right side of the point P0, the measurement data 186 in the case of FIG. 5 is different from the measurement data 188 in the case of FIG. Moreover, the distance between the two measurement values increases as the scanning position of the laser beam moves away from the point P0. In this specification, the measurement point P0 at which the measured value in the case of FIG. 5 and the measured value in the case of FIG. 6 start to separate is also referred to as a separation start point.

  The above measurement result can be explained by the relative relationship between the position of the laser spot on the measurement object and the position of the edge of the stepped portion. Specifically, in FIGS. 5 and 6, when the laser spot 132 is on the upper flat surface 138 of the measurement object 130 and does not hit the edge 134, the scanning position in FIG. 8A is on the left side of the point P 0. This corresponds to the case. When the right end of the laser spot 132 coincides with the edge 134 (when the laser spot 132 starts to hit the edge 134), it corresponds to the point P0 in FIG. When the center point of the laser spot 132 coincides with the edge 134, it corresponds to the point P1 moved by a half (w / 2) of the spot size from the point P0 in FIG. When the left end of the laser spot 132 coincides with the edge 134 (the moment when the laser spot 132 deviates from the upper flat surface 138), it corresponds to the point P3 moved by the spot size (w) from the point P0 in FIG. . However, since the amount of light received by the linear image sensor 120 reaches the detection limit at the point P2 before the scanning position reaches the point P3, measurement by the laser displacement meter becomes impossible.

[Data processing procedure]
As described above, a measurement error occurs when a step portion is measured using a triangulation laser displacement meter. If this measurement error is used, the position of the edge of the step portion can be detected easily and accurately. A specific procedure is shown in FIG.

  FIG. 9 is a flowchart showing the procedure for measuring the surface shape and the processing procedure for the measured data. 4 and 9, first, in the first measurement step, the measurement control unit 156 drives the moving mechanism 146 to measure the laser beam 116 while scanning the measurement range including the step. The surface shape of the object is continuously measured using the laser displacement meter 100 (step S100).

  Since the error at the edge portion described above appears in a range smaller than the laser spot size, the sampling interval by the laser displacement meter needs to be ½ or less of the laser spot size. In this case, the sampling interval of the laser displacement meter is desirably 1/10 or less of the spot size in order to accurately grasp the vertical change of the measured value. More preferably, the sampling interval of the laser displacement meter is set to 1/20 or less of the spot size.

  Next, the measurement controller 156 rotates the laser displacement meter 100 by 180 degrees around the central axis of the laser beam 116 by driving the C-axis drive mechanism 146C (step S105). When the C-axis rotation center of the C-axis drive mechanism 146C and the center axis of the laser beam 116 do not coincide with each other, the X-axis drive mechanism 146X and the 180-degree rotation drive using the C-axis drive mechanism 146C are performed. The laser displacement meter 100 is moved so that the position of the central axis of the laser beam 116 is maintained by at least one of the Y-axis drive mechanism 146Y.

  Next, in the second measurement step, the measurement control unit 156 continuously measures the same portion as in the first measurement step with the laser displacement meter 100 (step S110). Data (surface shape data 166) measured by the first and second measurement steps is stored in the memory 154.

  Next, data processing of the surface shape data 166 is performed by the data processing unit 158. The data processing unit 158 includes a step identification unit 160 and a data correction unit 162. First, the step identification unit 160 separates the measurement value of the first measurement step (referred to as M1) and the measurement value of the second measurement step (referred to as M2) within the measurement range of the surface shape data 166. A separation start point to be started (point P0 in FIG. 8A) is specified (step S115).

  Various methods can be conceived as methods for specifically specifying the separation start point of the measured value M1 and the measured value M2. For example, a point at which the difference M1-M2 between measured values exceeds a predetermined threshold may be set as the separation start point. Alternatively, an approximate curve representing the relationship between the measurement value difference M1-M2 and the scanning position may be obtained, and a point where the value of the approximate curve exceeds a predetermined threshold may be set as the separation start point.

  Next, the step identifying unit 160 identifies the step position based on the identified separation start point P0 (step S120). Specifically, the level difference specifying unit 160 is within the separation section in which the measurement value M1 from the first measurement step and the measurement value M2 from the second measurement step are separated (on the right side of the point P0 in FIG. 8A). ), A point P1 that is separated from the separation start point P0 by ½ of the spot size w of the laser beam is specified as a step position.

  Next, the data correction unit 162 corrects the measurement value from the separation start point P0 to the step position P1 (step S125). Specifically, the data correction unit 162 calculates the average value (190 in FIG. 8B) of the measurement value M1 from the first measurement step and the measurement value M2 from the second measurement step in the height direction in the section. Displacement. Thereafter, for example, the surface shape data may be further corrected by performing a filtering process such as a moving average.

  In the above, the scanning direction of the laser beam is an optical path surface (XZ plane) including the central axis 116C of the laser beam and the condensing spot 124 of the linear image sensor (light receiving unit) 120, as shown in FIGS. It is desirable that the directions be parallel. This is because, when the scanning direction and the optical path surface are parallel, the difference between the measured value M1 of the edge portion by the first measuring step and the measured value M2 of the edge portion by the second measuring step is the largest. In general, when viewed in plan from the direction along the laser beam (Z-axis direction), the scanning direction of the laser beam is not perpendicular to the optical path plane (if it is not parallel to the YZ plane), and at any angle. (However, the stepped portion needs to intersect the scanning direction). 5 and 6, if the scanning direction of the laser beam is not parallel to the YZ plane, there is a difference between the measured value M1 of the stepped portion by the first measuring step and the measured value M2 of the stepped portion by the second measuring step. Therefore, the step position can be specified.

[Effect of Embodiment 1]
As described above, according to the surface shape measuring apparatus 140 according to the first embodiment, after measuring the surface shape of the measurement object 130 including the stepped portion with the laser displacement meter 100, the laser displacement meter 100 is moved to the central axis of the laser beam 116. Rotate 180 degrees around the same position as before, and measure again the same location as before the rotation with the laser displacement meter 100. Then, the surface shape data of the same location measured before and after the rotation is compared, and the position of the edge is specified based on the position of the measurement point (separation start point) where the difference between the two data starts to occur. Thereby, the position of the step (edge) of the measuring object 130 can be detected easily, accurately and in a short time.

<Embodiment 2>
In the surface shape measuring apparatus according to the second embodiment, the configuration of the laser displacement meter is different from that in the first embodiment. FIG. 10 is a diagram schematically showing a configuration of a laser displacement meter used in the surface shape measuring apparatus according to the second embodiment.

  Referring to FIG. 10, a laser displacement meter 100A includes a light emitting unit 110, condensing lenses 118A and 118B as first and second optical systems, and a linear image sensor 120A as first and second light receiving units. , 120B. The condensing lens 118B and the linear image sensor 120B are disposed at positions obtained by rotating the condensing lens 118A and the linear image sensor 120A by 180 degrees around the central axis of the laser beam 116, respectively. The light emitting unit 110 includes a laser diode 112 and a lens 114.

  The laser beam 116 emitted from the laser diode 112 is shaped into substantially parallel light by the lens 114 and is irradiated onto the measurement object 130. The light diffusely reflected on the measurement object 130 is collected by the condensing lens 118A on the linear image sensor 120A arranged in the + γ angle direction with respect to the laser beam 116, and is reflected on the laser beam 116. The light is condensed by the condensing lens 118B on the linear image sensor 120B arranged in the angle direction of −γ (the direction opposite to + γ).

  A laser displacement meter 100A in FIG. 10 is attached to the surface shape measuring apparatus 140 shown in FIG. 4 in place of the laser displacement meter 100 in FIG. The displacement of the surface of the measurement object 130 is determined based on the position of the condensing spot 124A on the linear image sensor 120A and the position of the condensing spot 124B on the linear image sensor 120B. The other points in FIG. 10 are the same as those in FIG. 1, and therefore the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 11 is a flowchart showing a procedure for measuring a surface shape and a procedure for processing measured data in the apparatus according to the second embodiment. With reference to FIGS. 4, 10, and 11, first, the measurement control unit 156 drives the moving mechanism 146 to scan the laser beam 116 with respect to the measurement range including the step, while measuring the measurement object 130. Is continuously measured using the laser displacement meter 100 (step S200).

  In the second embodiment, condensing lenses 118A and 118B are provided in advance and linear image sensors 120A and 120B are provided in advance at positions that are line-symmetric with respect to the central axis of the laser beam 116. Therefore, it is not necessary to measure the same portion twice as in the first embodiment. As in the case of the first embodiment, when viewed in plan from the direction of the laser beam 116 (Z-axis direction), the scanning direction of the laser beam should not be perpendicular to the optical path surface (XZ plane) ( Do not be parallel to the YZ plane). Desirably, the scanning direction of the laser beam is parallel to the optical path plane (XZ plane).

  Next, the step identification unit 160 of the data processing unit 158 includes a measurement value (referred to as M1) by the first linear image sensor 120A and a measurement by the second linear image sensor 120B within the measurement range of the surface shape data 166. A separation start point from which the value (referred to as M2) begins to separate is identified (step S205).

  Next, the step identifying unit 160 identifies the step position based on the identified separation start point (step S210). Specifically, the step identifying unit 160 is configured to perform laser beam irradiation from the separation start point within the separation section where the measurement value M1 measured by the first linear image sensor 120A and the measurement value M2 measured by the second linear image sensor 120B are separated. A point separated by ½ of the spot size w is specified as a step position (step S210).

  Next, the data correction unit 162 corrects the measurement value from the separation start point to the step position (step S215). Specifically, the data correction unit 162 sets the average value of the measurement value M1 measured by the first linear image sensor 120A and the measurement value M2 measured by the second linear image sensor 120B as the displacement in the height direction in the section.

  As described above, according to the surface shape measurement apparatus according to the second embodiment, the first and second condenser lenses (optical systems) and the first and second condenser lenses (optical systems) disposed in line-symmetric positions with respect to the central axis of the laser beam. The surface shape of the measurement object including the stepped portion is measured using a laser displacement meter including the two linear image sensors (light receiving portions). Then, the position of the edge is specified based on the position of the measurement point (separation start point) at which the difference between the measurement values by the first and second linear image sensors starts to occur. As a result, the position of the step (edge) of the measurement object can be detected easily, accurately and in a short time.

<Embodiment 3>
The third embodiment discloses a machine tool provided with the surface shape measuring device of the first or second embodiment. Although the case where the machine tool is a vertical machining center is described below, the machine tool may be of other types such as a horizontal machining center or a lathe.

  FIG. 12 is a perspective view schematically showing the configuration of the machine tool according to the third embodiment. Referring to FIG. 12, machine tool 200 includes a machining device 10, an NC (Numerical Control) device 24, an ATC (Automatic Tool Changer) 28, and a computer 150.

  The processing apparatus 10 includes a bed 12, a column 14 installed on the bed 12, a spindle head 20 having a spindle 22, and a saddle 16 having a table 18.

  The spindle head 20 is supported on the front surface of the column 14 and is movable in the vertical direction (Z-axis direction). A tool (not shown) or a measurement head 42 is detachably attached to the tip of the main shaft 22. The main shaft 22 is supported by the main shaft head 20 so that its center axis (CL in FIG. 2) can rotate around a C-axis rotation center parallel to the Z-axis. The spindle head 20 includes a rotation drive unit 36 that rotates the spindle 22 at a high speed for machining the workpiece 2 and a rotation drive unit 38 that can control the rotation of the spindle 22 at a low speed. The latter rotation drive unit 38 corresponds to the C-axis drive mechanism 146C in FIG.

  The measurement head 42 incorporates the laser displacement meters 100 and 100A shown in FIG. 1 or FIG. 10, a control circuit for the laser displacement meter and a driving battery, and a communication device for performing wireless communication. The direction of the measurement head 42 (that is, the laser displacement meter 100, 100A) is controlled by the rotation drive unit 38 capable of low-speed feed control.

  The saddle 16 is disposed on the bed 12 and is movable in the front-rear horizontal direction (Y-axis direction). A table 18 is disposed on the saddle 16. The table 18 is movable in the left and right horizontal direction (X-axis direction). The workpiece 2 is placed on the table 18. The saddle 16 corresponds to the saddle 142 in FIG. 4, and the table 18 corresponds to the table 144 in FIG. The workpiece 2 corresponds to the measurement object 130 of FIG.

  The processing apparatus 10 linearly moves the measuring head 42 and the workpiece 2 in the three orthogonal directions of the X axis, the Y axis, and the Z axis, and measures at least about the C axis rotation center parallel to the Z axis. This is a machining center capable of rotating the head 42. Unlike the configuration of FIG. 1, the processing apparatus 10 may be configured to move the spindle head 20 that supports the measurement head 42 in the X-axis and Y-axis directions with respect to the workpiece 2. The structure which can rotate the table 18 which supports the thing 2 around the C-axis rotation center may be sufficient.

  The NC device 24 controls the overall operation of the processing device 10 including the above-described orthogonal three-axis and C-axis control. An ATC (automatic tool changer) 28 automatically changes the tool and the measuring head 42 with respect to the spindle 22. The ATC 28 is controlled by the NC device 24.

  FIG. 13 is a block diagram showing a functional configuration of a part related to the surface shape measuring apparatus in the machine tool of FIG. FIG. 13 shows a Z-axis feed mechanism 34, a Y-axis feed mechanism 32, and an X-axis feed mechanism 30 provided in the machining apparatus 10.

  12 and 13, the Z-axis feed mechanism 34 drives the spindle head 20 supported by the column 14 to move it in the Z-axis direction. The Y-axis feed mechanism 32 drives the saddle 16 disposed on the bed 12 to move in the Y-axis direction. The X-axis feed mechanism 30 drives the table 18 that is placed on the saddle 16 and supports the workpiece 2 to move in the X-axis direction. The NC device 24 controls the Z-axis feed mechanism 34, the Y-axis feed mechanism 32, and the X-axis feed mechanism 30, respectively. The X-axis feed mechanism 30, the Y-axis feed mechanism 32, and the Z-axis feed mechanism 34 respectively correspond to the X-axis drive mechanism 146X, the Y-axis drive mechanism 146Y, and the Z-axis drive mechanism 146Z in FIG.

  The computer 150 includes a processor 152, a memory 154, a communication device 168 for performing wireless communication with the measurement head 42, and the like. The processor 152 functions as the measurement control unit 156 and the data processing unit 158 described with reference to FIG. 4 by executing the program stored in the memory 154.

  The measurement control unit 156 continuously changes the relative positional relationship between the measurement head 42 and the workpiece 2 by cooperating with the NC device 24, whereby the laser beam 116 scans along the surface of the workpiece 2. To do. During the scanning of the laser beam 116, the measurement control unit 156 uses displacement data in the height direction (Z-axis direction) at a plurality of measurement points in the scanning direction of the laser beam 116 as surface shape data of the workpiece 2 from the measuring head 42. get. The specific procedure is as follows.

  First, based on the control from the measurement control unit 156, the NC device 24 is configured so that one of the X-axis feed mechanism 30 and the Y-axis feed mechanism 32, or the X-axis feed mechanism 30, the Y-axis feed mechanism 32, and the Z-axis feed mechanism. By driving at least two axes of the feed mechanism 34, the relative positional relationship between the measuring head 42 and the workpiece 2 is continuously changed.

  A PLC (Programmable Logic Controller) 26 built in the NC device 24 outputs a trigger signal to the communication device 168 in a predetermined cycle in synchronization with the driving of the feeding mechanism. When the communication device 168 receives the trigger signal, it transmits a measurement command f to the measurement head 42, and the measurement head 42 distances D from the measurement head 42 to the workpiece 2 according to the measurement command f (that is, displacement of the surface of the workpiece 2). Measure. Data F of the measured distance D is transmitted from the measurement head 42 to the measurement control unit 156 via the communication device 168.

  The PLC 26 further acquires positional information of the X-axis feed mechanism 30, the Y-axis feed mechanism 32, and the Z-axis feed mechanism 34 in accordance with the timing of distance measurement by the measurement head 42, so that the measurement head 42 Detect position data. The PLC 26 transmits the detected position data of the measurement head 42 to the measurement control unit 156.

  Based on the position data of the measurement head 42 acquired from the PLC 26 and the data F of the distance D acquired from the measurement head 42, the measurement control unit 156 is in the height direction at each measurement point along the scanning direction of the laser beam 116. The displacement data in the (Z-axis direction) is stored in the memory 154 as the surface shape data 166. When the position of the step of the workpiece 2 is detected using the laser displacement meter 100 having the configuration shown in FIG. 1, before and after the direction of the laser displacement meter 100 is rotated by 180 degrees with respect to the same portion of the workpiece 2. A total of two measurements are performed.

  The processor 152 further functions as a data processing unit 158 for performing data processing of the surface shape data 166 described above. The operation of the data processing unit 158 is as described in the first and second embodiments. As a result of the data processing by the data processing unit 158, the position of the step (edge) of the workpiece 2 can be detected easily and in a short time.

  The embodiment disclosed this time must be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  2 Workpiece, 10 Processing device, 16,142 Saddle, 18,144 Table, 20 Spindle head, 22 Spindle, 24 NC device, 30 X-axis feed mechanism, 32 Y-axis feed mechanism, 34 Z-axis feed mechanism, 36, 38 Rotation drive unit, 42 Measuring head, 100, 100A Laser displacement meter, 110 Light emitting unit, 112 Laser diode, 114 Lens, 116 Laser beam, 118, 118A, 118B Condensing lens (optical system), 120, 120A, 120B Linear image Sensor (light receiving unit), 130 measurement object, 132 laser spot, 134 edge, 140 surface shape measuring device, 146 moving mechanism, 146X X-axis drive mechanism, 146Y Y-axis drive mechanism, 146Z Z-axis drive mechanism, 146C C-axis drive Mechanism, 150 computer, 152 processor, 15 Memory, 156 measurement control portion, 158 data processing unit, 160 stepped particular unit, 162 data correction unit, 166 surface shape data, 200 a machine tool, P0 separation start point, P1 step position.

Claims (7)

A surface shape measuring device for measuring the surface shape of a measurement object including a step,
Emitting unit for emitting a light beam toward the measurement object, wherein the light beam optical system for condensing the scattered light from the object to be measured, and detects the luminance distribution of the optical system thus condensed light A displacement meter that measures the displacement of the surface of the measurement object based on the barycentric position of the luminance distribution at the light receiving unit,
A moving mechanism for scanning the light beam by relatively moving the displacement meter and the measurement object;
A first measurement step of continuously measuring the displacement of the surface of the measurement object by the displacement meter while scanning the light beam by the moving mechanism in a direction intersecting the step, and rotationally symmetric the light beam The same location as the first measurement step is continuously measured by the displacement meter in a state where the arrangement of the optical system and the light receiving unit is rotated 180 degrees with respect to the case of the first measurement step. A measurement controller configured to perform a second measurement step
A surface shape measurement apparatus comprising: a step specifying unit that specifies a position of the step based on a separation start point at which a measurement value obtained by the first measurement step and a measurement value obtained by the second measurement step start to separate.   The step identifying unit is ½ of the spot size of the light beam from the separation start point in a section where the measurement value obtained by the first measurement step and the measurement value obtained by the second measurement step are separated. The surface shape measuring apparatus according to claim 1, wherein a point separated by a distance is specified as a step position.   The value of the surface displacement at each measurement point from the separation start point to the specified step position is set to the average value of the measurement value obtained by the first measurement step and the measurement value obtained by the second measurement step. The surface shape measuring apparatus according to claim 2, further comprising a data correction unit that performs the correction.   The scanning direction of the light beam is not perpendicular to an optical path surface including the light beam and a light collection position of the light receiving unit when viewed in plan from the direction along the light beam. The surface shape measuring apparatus of any one of Claims. In the first measurement step, the light receiving unit is arranged at one of the front and rear in the scanning direction of the light beam with respect to the light beam,
5. The surface shape measurement according to claim 1, wherein, in the second measurement step, the light receiving unit is disposed on the other of the front and rear in the scanning direction with respect to the light beam. apparatus. A surface shape measuring device for measuring the surface shape of a measurement object including a step,
A displacement meter that continuously measures the displacement of the surface of the measurement object;
The displacement meter is
A light emitting unit that emits a light beam toward the measurement object;
First and second optical systems for collecting scattered light of the light beam from the measurement object;
And a first and second light receiving portions for detecting respective intensity distributions of the first and the second optical system thus condensed light,
The second optical system and the second light receiving unit are arranged at positions where the first optical system and the first light receiving unit are rotated by 180 degrees with the light beam as a rotational symmetry axis, respectively.
The displacement meter measures the displacement of the surface of the measurement object based on the barycentric position of the luminance distribution of each of the first and second light receiving units,
The surface shape measuring device further includes:
A moving mechanism for scanning the light beam by relatively moving the displacement meter and the measurement object;
A measurement control unit configured to continuously measure the displacement of the surface of the measurement object by the displacement meter while scanning the light beam by the moving mechanism in a direction crossing the step;
A surface shape measuring apparatus comprising: a step specifying unit that specifies a position of the step based on a separation start point at which a measurement value by the first light receiving unit and a measurement value by the second light receiving unit start to separate.   A machine tool comprising the surface shape measuring device according to claim 1.

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