JP2015190885A - edge detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an edge detection device capable of accurately detecting an edge of even a workpiece which has a chamfered edge to be uneven in surface height, in a small size at a low cost.SOLUTION: A floodlight (4, 5, 6, 7, 8) irradiates an upper surface of a workpiece 2 with condensed illumination light from a perpendicular direction, and a height detection part (11, 12, 13) detects a relative height of the floodlight to the upper surface on the basis of a first reflected light component having an optical axis in an oblique direction to the perpendicular direction, out of diffuse reflected light resulting from diffuse reflection on the upper surface of the illumination light, and a driving part adjusts the relative height into a prescribed range on the basis of the detection result of the height detection part and moves a relative position of the floodlight to the workpiece 2 in a view from the perpendicular direction, on a prescribed path, and an edge detection part (8, 9, 10, 13) receives, in a plurality of relative positions, a second reflected light component having an optical axis different from the optical axis of the first reflected light component, out of the diffuse reflected light and detects an edge of the workpiece 2 on the basis of variation in amount of received light.

Description

  The present invention relates to an apparatus that is mounted on a machine tool such as an electric discharge machine or a cutting machine and detects an edge of a workpiece.

  In general, before performing high-accuracy machining with a wire electric discharge machine or the like, a setup process is performed in which a reference surface of a workpiece (workpiece) is aligned with high accuracy with respect to a scanning axis of the machining machine. In the setup process, for example, the workpiece is fixed to a mounting jig on the scanning axis of the processing machine, a dial gauge is pressed against the reference surface (for example, the side surface of the workpiece) for alignment, and the reference for alignment The position of the workpiece is manually adjusted so that the dial gauge value does not change even if the scanning axis corresponding to the surface is moved. However, the manual setup process takes time, and there is a problem that the alignment result varies depending on the skill of the operator.

  Therefore, there is a method in which an on-machine measurement sensor is mounted on the processing machine and the setup is automatically performed in order to shorten the work time and reduce the variation by the worker. In general, as an on-machine measurement sensor, there is an optical sensor capable of non-contact measurement in addition to a contact sensor. The optical sensor irradiates laser light from the upper surface of the workpiece, detects reflected light, and measures the edge position in a non-contact manner. Therefore, there is an advantage that a thin reference hole and a soft workpiece can be measured. However, for example, the edge of the workpiece may be chamfered. When measuring the position of the chamfered edge, the height of the workpiece surface changes depending on the position. Therefore, if the sensor does not have a focus adjustment function, the focused spot becomes large and high-precision measurement cannot be performed.

  As a technique for measuring the edge position with high accuracy even for a chamfered workpiece, for example, a technique disclosed in Patent Document 1 has been proposed. Patent Document 1 always performs autofocus using the principle of triangulation and an actuator, and measures the edge position with high accuracy. The laser beam is irradiated obliquely to the workpiece surface, the reflected light is condensed on the optical position detection sensor, and the workpiece surface height is detected using the principle of triangulation. Furthermore, using the height information on the workpiece surface, the actuator connected to the objective lens is driven to perform autofocus so that the focus state is always maintained. A position where the height difference from the reference plane for height detection is equal to or greater than a certain threshold value ΔZ is defined as an edge position. Since edge detection is performed while performing autofocusing, even a chamfered edge can be detected with high accuracy.

JP 2000-146532 A.

  In the configuration disclosed in Patent Document 1, since the laser beam is irradiated obliquely with respect to the workpiece surface, the measurement position is shifted in the horizontal direction when the height of the workpiece surface changes. Therefore, it is necessary to always perform focus adjustment to maintain the relative positional relationship between the workpiece surface and the lens, and the lens must be continuously driven using an actuator. In order to mount a driving component such as an actuator, the configuration disclosed in Patent Document 1 has a problem that the edge detection device is large and expensive.

  The present invention has been made in order to solve the above-described problems, and is small, low-cost, and highly accurate even for a workpiece having a chamfered edge and whose surface height varies. An object of the present invention is to provide an edge detection device capable of detecting the above.

  The edge detection device according to the present invention has a light projecting unit that projects the condensed irradiation light on the upper surface of the object to be detected from the vertical direction, and the vertical direction of the diffuse reflection light in which the irradiation light is diffusely reflected on the upper surface. A height detection unit that detects the relative height of the light projecting unit with respect to the upper surface based on a first reflected light component having an optical axis in an oblique direction, and a relative value based on the detection result of the height detection unit While adjusting the height within a predetermined range and moving the relative position when viewed from the vertical direction with respect to the object to be detected of the light projecting unit, and a diffused reflected light at a plurality of relative positions An edge detector that receives a second reflected light component having an optical axis different from the optical axis of the first reflected light component and detects an edge of the detected object based on a change in the amount of received light. .

  According to the edge detection device of the present invention, the light projecting unit projects the condensed irradiation light onto the upper surface of the detection object from the vertical direction, and the height detection unit diffuses and reflects the irradiation light on the upper surface. Based on the first reflected light component having the optical axis in the oblique direction with respect to the vertical direction in the diffuse reflected light, the relative height of the light projecting unit with respect to the upper surface is detected. Based on the detection result, the relative height is adjusted within a predetermined range, and the relative position when viewed from the vertical direction with respect to the object to be detected of the light projecting unit is moved along a predetermined path. The second reflected light component having an optical axis different from the optical axis of the first reflected light component among the diffuse reflected light is received at a plurality of relative positions, and the edge of the detected object is detected based on the change in the amount of received light. Therefore, for workpieces with varying surface height such as chamfered edges Also, small, it detects edges with high accuracy at low cost.

It is a perspective view of the processing machine carrying the edge detection apparatus by Embodiment 1 of this invention. It is a figure which shows the structure of the edge detection sensor in the edge detection apparatus by Embodiment 1 of this invention. It is a figure showing an example of the result of having measured the surface of the work before processing with a three-dimensional measuring machine. It is a figure for demonstrating the height detection method in the edge detection apparatus by Embodiment 1 of this invention. It is a figure for demonstrating the detection method of the right-angled edge in the edge detection apparatus by Embodiment 1 of this invention. It is a figure showing an example of the result of having detected the edge in the different position of a workpiece | work in the edge detection apparatus by Embodiment 1 of this invention. It is a flowchart of the averaging algorithm at the time of edge detection in the edge detection apparatus by Embodiment 1 of this invention. It is a figure for demonstrating the averaging algorithm at the time of edge detection in the edge detection apparatus by Embodiment 1 of this invention. It is a figure explaining an example of the edge calculation method in the edge detection apparatus by Embodiment 1 of this invention. It is a figure explaining the subject in the case of detecting the chamfered edge. It is a figure explaining the height detection in the chamfering edge in the edge detection apparatus by Embodiment 1 of this invention. It is a figure explaining the focus adjustment method in the edge detection apparatus by Embodiment 1 of this invention. It is a figure explaining the edge detection at the time of irradiating light to the workpiece | work surface from the diagonal direction. It is a figure which shows the structure of the edge detection sensor in the edge detection apparatus by Embodiment 2 of this invention. It is a figure which shows the structure of the edge detection sensor in the edge detection apparatus by Embodiment 3 of this invention. It is a figure which shows the structure of the edge detection sensor in the edge detection apparatus by Embodiment 4 of this invention. It is a figure which shows the structure of the edge detection sensor in the edge detection apparatus by Embodiment 5 of this invention.

Embodiment 1 FIG.
FIG. 1 is a perspective view of a processing machine equipped with an edge detection device according to Embodiment 1 of the present invention. The edge detection apparatus includes an edge detection sensor 101 and a drive unit. The edge detection sensor 101 is attached to the side surface of the processing head 1 of the processing machine. The edge detection sensor 101 may be simply called a sensor. A workpiece 2 which is a workpiece and is a detection object for edge detection is fixed to a scanning unit 3 (stage) of the processing machine by an attachment jig 14. The edge detection sensor 101 irradiates light on the upper surface of the work 2 and detects the presence or absence of reflected light from the work 2 to perform edge detection.

  In the present embodiment, the processing machine operates using the three directions (X direction, Y direction, and Z direction) shown in FIG. 1 as scanning axes. In the processing machine according to the present embodiment, the scanning unit 3 moves using two directions (X direction and Y direction) that are parallel (that is, horizontal) and orthogonal to the upper surface of the scanning unit 3 as scanning axes, and the processing head 1 is Suppose that the direction of movement perpendicular to the upper surface of the scanning unit 3 (that is, the vertical direction) (Z direction) is used as the scanning axis. However, the present invention is not necessarily limited to this. For example, the scanning unit 3 may move in three directions (X direction, Y direction, and Z direction) as scanning axes. In the following description, the X direction, the Y direction, and the Z direction refer to the three directions shown in FIG. 1 unless otherwise specified.

  In the present embodiment, the edge detection device is incorporated in a processing machine, and the processing head 1 and the scanning unit 3 also function as a drive unit of the edge detection device. The drive unit of the edge detection device has a function of moving the relative position between the edge detection sensor 101 and the workpiece 2 that is the object to be detected. The drive unit of the edge detection apparatus operates under the control of a control unit (not shown), but the function of controlling the operation of the drive unit can be considered as a part of the drive unit.

  FIG. 2 is a diagram illustrating the configuration of the edge detection sensor 101, and is a configuration diagram of the configuration of the edge detection sensor 101 as viewed from the side (Y direction in FIG. 1). In FIG. 2, the solid line arrow represents the progress of light, and the alternate long and short dash line represents the optical axis. The same applies to the subsequent configuration diagrams. The light source 4 is configured by a laser, an LED, or the like, and for example, a semiconductor laser is used. The light projecting lens 5 is configured so that the light emitted from the light source 4 is parallel light. The distance between the light source 4 and the projection lens 5 is optimally set in accordance with the lens curved surface shape of the projection lens 5. In other words, the distance between the light source 4 and the projection lens 5 is optimally set in consideration of parameters such as the focal length of the projection lens 5. The light that has become parallel light through the light projection lens 5 is reduced to an appropriate size by the light projection aperture 6. The condensing spot diameter of the light irradiated onto the workpiece 2 by the light projection aperture 6 can be determined.

  Next, the beam splitter 7 has a function of turning parallel light through the light projection lens 5 and turning back the light focused by the light projection aperture 6 in the direction of the work 2, and includes a plate type and a cube type. The objective lens 8 is configured to collect the parallel light reflected by the beam splitter 7, and is adjusted so that the surface of the work 2 (work surface) is at the condensing position. The objective lens 8 is disposed so that the optical axis of the irradiation light on the workpiece surface is in a direction perpendicular to the workpiece surface. Accordingly, the work surface is irradiated with light from a direction perpendicular to the work surface. Here, the optical axis is a virtual light beam that is representative of the entire irradiated light beam or the entire received light beam, and is an axis that represents the traveling direction of the entire light beam.

  The light source 4, the projection lens 5, the projection diaphragm 6, the beam splitter 7, and the objective lens 8 constitute a projection unit. The light projecting unit has a function of irradiating (projecting) the condensed irradiation light onto the surface of the workpiece 2. The surface of the work 2 or the work surface refers to the upper surface of the work 2 unless otherwise specified. Usually, the workpiece 2 is arranged so that the surface of the workpiece is horizontal. In this case, the direction perpendicular to the surface is the vertical direction. Light irradiated on the workpiece surface through the objective lens 8 is diffusely reflected on the workpiece surface. Generally, as will be described later, the workpiece surface before processing is rough, and the irradiated light is diffusely reflected.

  Of the light diffusely reflected on the workpiece surface, the component reflected in the vicinity of the vertical direction, that is, the component having the optical axis in the vertical direction passes through the objective lens 8 again and becomes parallel light. The beam splitter 7 reflects the work 2 and transmits the light taken in from the objective lens 8. The light receiving lens 9 is configured to collect the light reflected from the work 2, taken in from the objective lens 8, and transmitted through the beam splitter 7 onto the edge detection light receiving element 10. The distance between the light receiving lens 9 and the edge detecting light receiving element 10 is optimally set according to the curved surface shape of the light receiving lens 9.

  For example, a photodiode is used as the edge detection light-receiving element 10 and has a function of converting the intensity of light reflected on the workpiece surface into an electrical signal. The converted electric signal is sent to the signal calculation unit 13. The objective lens 8, the light receiving lens 9, the edge detection light receiving element 10, and the signal calculation unit 13 constitute an edge detection unit. The edge detection unit receives a component of the diffusely reflected light diffusely reflected on the surface of the workpiece 2 that is reflected in the vicinity of the vertical direction, that is, a component having an optical axis in the vertical direction with respect to the workpiece surface. It has a function of detecting the position of the edge based on the change.

  In addition, the height detection lens 11 is a component diffused and reflected in an oblique direction with respect to the vertical direction out of the light that is irradiated on the surface of the work 2 and diffusely reflected on the surface of the work 2, that is, an optical axis in the oblique direction. It is configured to take in the component it has and condense it on the light-receiving element 12 for height detection. Here, of the diffusely reflected light, a component having an optical axis in an oblique direction with respect to the vertical direction and taken into the height detection lens 11 is a first reflected light component. Of the light diffusely reflected on the surface of the workpiece 2, a component having an optical axis in a direction perpendicular to the workpiece surface (vertical direction) is a second reflected light component. The height detection lens 11, the height detection light receiving element 12, and the signal calculation unit 13 constitute a height detection unit. The height detection unit has a function of receiving the first reflected light component and detecting the relative height of the workpiece surface based on the incident direction (direction of the optical axis) of the received light.

  For example, as shown in the area surrounded by the broken line at the lower left in FIG. 2, the height detection lens 11 is a combination of a lens and a triangular prism, or a lens divided into two at the center of the curved surface, and is incident obliquely. Any configuration can be used as long as the light thus collected can be collected on the light receiving element for height detection. From now on, for the sake of simplicity, it is described as a single lens shape. The height detecting light receiving element 12 detects that the position on the height detecting light receiving element 12 where the reflected light is condensed is changed when the height of the workpiece surface is changed according to the principle of triangulation. For example, an optical position detection element PSD (Position Sensitive Detector), a linear imager, or a two-dimensional imager is used. The electrical signal detected by the height detection light receiving element 12 is sent to the signal calculation unit 13. The optical axis of the height detection lens 11 and the optical axis of the light detection lens 9 for edge detection are shifted from each other.

  Here, the workpiece | work 2 used for a process is demonstrated. For the workpiece 2, a metal workpiece such as a super hard material, stainless steel, or copper is generally used. The surface of the workpiece 2 before processing has a minute uneven shape due to cutting marks or the like attached when it is cut out. That is, the surface of the workpiece 2 before processing is a rough surface. FIG. 3 is a diagram illustrating an example of a result of measuring the surface of the workpiece 2 before processing with a three-dimensional measuring machine, and is an example of a result of measuring the workpiece surface of the cemented carbide material. FIG. 3A is a 2D map (two-dimensional map) of the uneven shape on the workpiece surface. FIG. 3B shows a cross-sectional shape of the workpiece surface on the XZ plane at a certain position in the Y direction. The workpiece surface has minute irregularities of 2 to 3 μm and is rough.

  Therefore, when the focused beam is irradiated on the workpiece surface, the intensity distribution of the reflected light with respect to the reflection angle changes depending on the position on the workpiece 2. Therefore, the intensity of the reflected light received by the light receiving element varies greatly depending on the position on the work 2, and a stable detection signal (output of the light receiving element) cannot be obtained, resulting in variations. Therefore, it is desirable to set the aperture of the projection beam in the projection aperture 6 so that the diameter of the condensed spot irradiated on the workpiece surface includes a plurality of irregularities. Ideally, the edge detection accuracy is improved when the diameter of the focused spot irradiated onto the workpiece surface is smaller. However, if the work surface has a minute uneven shape, if the diameter of the focused spot is made too small, the intensity distribution with respect to the reflection angle of the reflected light easily changes depending on the irradiation position due to the unevenness, and the detection signal The variation of the is increased. Therefore, the focused spot diameter needs to have an appropriate size with high detection accuracy while suppressing variations in detection signals. The diameter of the focused spot is determined according to the purpose of use.

  Here, the diameter D of the airy disk of the focused spot is given by equation (1) by diffraction calculation. In equation (1), λ is the wavelength of light, f1 is the focal length of the objective lens, and d is the aperture diameter of the projection aperture 6. For example, assuming that the spot diameter D is 8 μm so that the airy disk of the condensing spot includes about 3 irregularities, the aperture diameter d of the projection aperture 6 is obtained when the wavelength λ = 660 nm and the focal length f1 of the objective lens = 18 mm. = 3.6 mm. Here, the spot diameter is determined based on the opening diameter of the projection aperture 6, but the spot diameter may be determined based on the lens diameter of the projection lens 5 without using the projection aperture 6.

  When the projection aperture diameter d and the condensing spot diameter D are determined, the focal depth ΔZ of the condensing spot of the irradiation light can be calculated. In the following description, when it is simply described as the depth of focus without any particular explanation, it indicates the depth of focus of the condensed spot of the irradiation light on the work surface. For example, in the case of the above conditions, when the defocus amount that is 1.5 times the spot diameter at the time of condensing is the depth of focus ΔZ, the depth of focus ΔZ is 120 μm. If the height of the workpiece surface can be adjusted within this depth of focus, the spot diameter changes only to the extent that there is no problem in performing edge detection, so that the edge can be detected without degrading accuracy. Here, the depth of focus ΔZ is a defocus amount that is 1.5 times the spot diameter at the time of condensing, but it may be in a range that does not actually deteriorate the accuracy at the time of edge detection. Here, the edge detection is to detect (measure) the position of the edge in addition to the presence or absence of the edge, and the accuracy at the time of edge detection is the accuracy of the position of the detected (measured) edge.

  Next, a method for detecting the height of the workpiece surface using the height detection lens 11 and the height detection light receiving element 12 will be described. FIG. 4 is a view for explaining a height detection method in the edge detection apparatus of the present embodiment, and is a view of the edge detection sensor 101 as viewed from the side. FIG. 4A shows a case where the surface of the workpiece 2 is at the focal position of the objective lens 8. The height detection lens 11 is constituted by a convex lens and a triangular prism, for example, but is shown here as one lens shape. The distance from the principal point of the height detection lens 11 to the light receiving surface of the height detecting light receiving element 12 is a, and the distance to the workpiece surface is b. Further, let c be the distance from the optical axis of the height detection lens 11 to the center of the light receiving element 12 for height detection, and d be the distance to the optical axis of the objective lens 8. At this time, the component diffused and reflected in the oblique direction out of the light scattered on the workpiece surface is condensed by the height detection lens 11 at the center of the height detection light receiving element 12, and the expressions (2) and (3) ) Is satisfied. Here, f2 is the focal length of the height detection lens 11.

  On the other hand, FIG. 4B shows a case where the surface of the workpiece 2 changes by a distance L in the −Z direction of FIG. The height of the workpiece surface moves away from the focal position. For this reason, the incident angle of the reflected light component to the height detection lens 11 changes and the direction of the optical axis of the reflected light component incident to the height detection lens 11 changes, so that the light is condensed by the height detection lens. The height detection light receiving element 12 is changed by a distance ΔH in the + X direction. At this time, the relationship of Expression (4) is satisfied. Here, the intersection of the optical axis of the reflected light for height detection and the focal plane (surface at the focal position) at the time of defocusing (when the height of the surface of the workpiece 2 is changed) is defined as A. If the intersection between the optical axis of the light projected on the surface and the focal plane is B, d ′ represents the difference in position between the intersection A and the intersection B.

  Since d ′ satisfies the relationship of Expression (5), ΔH is expressed by Expression (6) from Expression (3), Expression (4), and Expression (5). For example, if a = 75 mm, b = 40 mm, and d = 21 mm, when L = 1 mm, ΔH≈1 mm, and the amount of displacement of the condensing position on the height detecting light receiving element 12 is set to the height of the workpiece surface. It can be made equal to the amount of displacement.

  FIG. 4C shows a case where the surface of the workpiece 2 changes by a distance L in the + Z direction. The height of the workpiece surface approaches the sensor side from the focal position. Therefore, since the incident angle to the height detection lens 11 changes, the condensing position on the height detection light receiving element 12 that is condensed by the height detection lens 11 is -X based on the same idea as described above. The distance ΔH changes in the direction. As described above, when the position (height) of the workpiece surface with respect to the sensor changes, the spot condensing position on the height detecting light receiving element 12 changes. When the spot position (condensing position) on the light receiving element for height detection changes by ΔH as described above, the height displacement amount L on the workpiece surface can be obtained from Expression (6) as Expression (7). it can.

  Therefore, the height of the workpiece surface can be calculated by measuring the spot position on the height detecting light receiving element 12. If the displacement L between the height of the workpiece surface and the focal position of the objective lens is 0 ≦ L ≦ ΔZ / 2 with respect to the focal depth ΔZ of the focused spot of the irradiated light, the edge can be measured with high accuracy. is there. That is, when the displacement L between the height of the workpiece surface and the focal position of the objective lens is within the depth of focus centered on the focal position of the objective lens 8, the edge can be measured with high accuracy. However, if the displacement L between the height of the workpiece surface and the focal position of the objective lens is out of the depth of focus (L> ΔZ / 2), the Z-direction position of the machining head is changed by, for example, L to change the height of the workpiece surface. Adjust so that is within the depth of focus. In this way, when the workpiece surface height is outside the depth of focus, the workpiece surface height is always adjusted within the focal depth by moving the Z-direction height of the machining head and adjusting the sensor height. can do.

  Next, an edge detection method will be described. FIG. 5 is a diagram for explaining a method for detecting a right-angled edge in the edge detection apparatus according to the present embodiment. FIG. 5 is an image view of the relative positions of the edge detection sensor 101 and the workpiece 2 at each scanning position in the X direction of the scanning unit 3 as viewed from the side, and a diagram showing the relationship between the scanning position and the output of the light receiving element 10 for edge detection. It consists of and. An edge detection sensor 101 is installed above the workpiece 2. The scanning unit 3 is moved by a distance ΔX in the X direction so that the edge detection sensor 101 crosses the edge (X = X2) of the workpiece 2, and a signal is acquired by the edge detection light receiving element 10. At the position X1, the edge detection sensor 101 is on the work 2, and the irradiation light is collected on the work 2 and reflected light is obtained. Therefore, the output V1 is obtained from the light receiving element for edge detection.

  Next, when the scanning unit 3 moves and the edge detection sensor 101 moves on the edge of the workpiece 2 (position X2), a part of the condensed spot comes out of the workpiece 2, and thus the workpiece 2 The output obtained from the edge detection light-receiving element 10 is lower than when the edge detection sensor 101 is on the top. The output at this time is V2 = α * V1 (0 <α <1). Finally, when the edge detection sensor 101 moves out of the workpiece 2, almost no reflected light from the surface of the workpiece 2 can be obtained, so that almost no output from the edge detection light receiving element 10 can be obtained. Here, the upper surface of the scanning unit 3 can be configured not to reflect light. Further, if the upper surface of the scanning unit 3 is sufficiently out of the range of the focal depth, the light is not collected, so that the edge detection light receiving element 10 hardly receives the reflected light. In this way, the position where the output of the light receiving element 10 for edge detection becomes V2 can be measured as the edge position. For example, α = 0.5.

  However, the edge of the workpiece 2 that is actually used for processing is fluctuated by a minute uneven shape of several μm. FIG. 6 is a diagram illustrating an example of a result of detecting edges at different positions Y1, Y2, and Y3 of the workpiece 2 in the Y direction in the edge detection apparatus according to the present embodiment. In FIG. 6, the horizontal axis represents the position in the X direction, and the vertical axis represents the magnitude of the output of the edge detection light receiving element 10. When the position in the Y direction is different, the edge position to be detected varies due to the influence of the unevenness of the edge portion. Therefore, variation in edge detection can be reduced by using the following averaging method.

  FIG. 7 is a flowchart of an averaging algorithm (average method) at the time of edge detection in the edge detection apparatus of the present embodiment. FIG. 8 is a diagram for explaining an averaging algorithm at the time of edge detection in the edge detection apparatus of the present embodiment. FIG. 8 shows an example of a detection path when the work 2 is viewed from the top. The averaging algorithm will be described with reference to FIGS. First, after starting edge detection, the edge detection sensor 101 moves a distance ΔX in the X direction so as to cross the edge. For example, ΔX = 50 μm. At this time, a signal of the edge detection light receiving element 10 for the position in the X direction is acquired and stored in the signal calculation unit 13. When the movement of the distance ΔX in the X direction is completed, the movement of the distance ΔY in the Y direction is performed. For example, ΔY = 10 μm. When the movement in the Y direction is completed, the edge detection sensor 101 again moves the distance ΔX in the −X direction so as to cross the edge, and then moves the distance ΔY in the Y direction. In this way, as shown in FIG. 8, the movement is performed along the zigzag route, and the measurement is finished when the movement is completed M times by the distance ΔY in the Y direction. For example, M = 40.

  FIG. 9 is a diagram for explaining an example of an edge calculation method in the edge detection apparatus according to the present embodiment. FIG. 9A shows an output signal from the edge detection light-receiving element 10 obtained in each of M edge detections. FIG. 9B shows a signal obtained by averaging the M output signals from the edge detection light receiving element 10. As shown in FIG. 9, the data of the output signal from the edge detection light receiving element 10 with respect to the X direction position detected (measured) M times is averaged, and the X direction position where V2 = α * V1 with respect to the maximum value V1 is signaled. By calculating by the calculation unit, the edge position can be detected (measured) with high accuracy. In this way, by averaging the results of detecting the edge a plurality of times, it is possible to reduce the influence of the variation in the edge position due to minute unevenness and detect the edge position with high accuracy. Here, the zigzag path for averaging is merely an example, and different positions in the Y direction may be detected a plurality of times, and the obtained signal outputs may be averaged to detect the edge position. Further, the number of measurement points M = 1 may be used, and if there is little variation, an edge may be detected from one signal.

  As described above, if the edge is a right angle, if the focus adjustment is performed on the upper surface of the work 2, the upper surface of the work 2 is within the depth of focus up to the edge position. Edges can be measured with high accuracy using a light spot. However, another problem occurs when the edge is chamfered. FIG. 10 is a diagram illustrating a problem in the case of detecting a chamfered edge (chamfer edge). FIG. 10 is an image view of the relative positions of the edge detection sensor 101 and the workpiece 2 at each scanning position in the X direction of the scanning unit 3 as viewed from the side. When the workpiece 2 moves in the X direction when detecting the edge, the height of the surface of the workpiece 2 at the chamfered portion (the chamfered portion) is adjusted even when the focus is adjusted on the upper surface of the workpiece 2. May change out of the depth of focus. Therefore, edge detection is performed with a spot diameter larger than that of the focused spot, and the edge position detection accuracy is lowered. In order to solve this, a height adjustment method using a height detection unit at the time of edge detection will be described.

  FIG. 11 is a diagram for explaining the height detection at the chamfered edge in the edge detection apparatus of the present embodiment. The upper part of FIG. 11 is an image view of the relative position between the edge detection sensor 101 and the workpiece 2 as viewed from the side. The middle diagram of FIG. 11 is a diagram for explaining a state of a light spot (light projection spot) irradiated on the surface (upper surface) of the workpiece 2. The lower part of FIG. 11 is a diagram for explaining the operation of the height detection unit. FIG. 11A shows a state in which the edge detection sensor 101 is positioned above the flat portion on the upper surface of the workpiece and the focus adjustment is performed on the flat portion on the upper surface of the workpiece. The light projection spot is condensed on the upper surface of the workpiece, and the light taken in by the height detection lens 11 is condensed at the center position in the X direction of the height detection light receiving element 12. Here, the flat portion refers to a portion excluding the chamfered portion of the upper surface of the work 2, and refers to an average flat region excluding minute irregularities on the upper surface.

  Here, the light projection spot is a spot of light irradiated (projected) on the surface of the work 2, and includes both cases where the surface of the work 2 is within the focal depth and outside the focal depth. Contains. On the other hand, the condensed spot refers to a spot of light irradiated on the surface of the work 2 when the surface of the work 2 is at the focal length of the objective lens 8 or within the focal depth.

  Next, as shown in FIG. 11B, it is assumed that the position in the X direction is located in the chamfered region, and the position in the Z direction on the workpiece surface is changed by Z1 (−ΔZ / 2 <Z1 <0). Since the surface of the work 2 is within the depth of focus, the projected spot diameter hardly changes. Further, the spot position on the height detecting light receiving element 12 changes by a distance ΔH1 in the + X direction. The signal calculation unit 13 calculates the workpiece height change amount Z1 from the spot position change amount ΔH1, and determines whether −ΔZ / 2 <Z1 <ΔZ / 2. Since Z1 satisfies the above condition, the detection of the edge is continued.

  FIG. 11C is a diagram when the height of the workpiece surface changes by Z2 (Z2 <−ΔZ / 2). The spot position on the height detecting light receiving element 12 changes by a distance ΔH2 (ΔH2> ΔH1). In the case of FIG. 11C, since Z2 <−ΔZ / 2, the signal calculation unit 13 detects that the height of the workpiece surface has changed outside the depth of focus.

  FIG. 12 is a diagram for explaining a focus adjustment method in the edge detection apparatus according to the present embodiment. FIG. 12 is an image view of the relative position between the edge detection sensor 101 and the workpiece 2 as viewed from the side. As shown in FIG. 12, the Z direction position of the machining head 1 is moved, and the Z direction position of the edge detection sensor 101 is brought closer to the workpiece 2 by a distance ΔZ2. As a result, the height of the workpiece surface falls within the depth of focus, and the spot position on the height detecting light receiving element 12 also moves in the center direction. Thus, if the height detection lens 11 and the height detection light receiving element 12 are used, it is possible to detect that the height of the workpiece surface has moved out of the depth of focus, and the position of the machining head 1 in the Z direction can be determined. By moving, the height of the workpiece surface can be adjusted within the depth of focus. The edge detection apparatus according to the present embodiment operates as described above.

  As described above, in the edge detection apparatus of the present embodiment, the light projection beam (irradiation light) is projected (irradiated) perpendicularly to the flat portion of the workpiece surface. That is, in the edge detection apparatus of the present embodiment, the workpiece surface is irradiated with irradiation light with the vertical direction as the optical axis. Therefore, even if the height of the workpiece surface changes at the chamfered portion, the measurement position does not shift horizontally, and if the workpiece surface position is within the focal depth of the focused spot of the irradiated light, the edge Measurement can be continued. If it is detected that the workpiece surface position is out of the depth of focus, the Z-direction position of the machining head 1 is moved, and the edge detection sensor 101 is moved to adjust the workpiece surface position to be within the depth of focus. Therefore, the edge detection apparatus according to the present embodiment does not require a driving component such as an actuator. As described above, the workpiece 2 is usually arranged so that the flat portion of the workpiece surface is horizontal. In this case, the direction perpendicular to the flat portion is the vertical direction.

  When the irradiation light is irradiated from an oblique direction, the position where the light is irradiated shifts in the horizontal direction when the height of the workpiece surface changes. Therefore, the position where the edge is detected is shifted in the horizontal direction, and an error occurs in the detected edge position. FIG. 13 is a diagram for explaining edge detection when the work surface is irradiated with light from an oblique direction. The center diagram in FIG. 13 represents the case where the height of the workpiece surface is at the focal position, and the left and right diagrams in FIG. 13 represent the case where the workpiece surface height is deviated from the focal position. When the height of the workpiece surface is deviated from the focal position, the detected position is deviated in the horizontal direction. Although it is conceivable to solve this problem by adding high-response drive parts such as actuators and performing high-precision autofocusing, there arises a problem that the apparatus becomes large and expensive. On the other hand, according to the edge detection apparatus of the present embodiment, such a problem does not occur.

  Moreover, the edge detection apparatus of this Embodiment detects the edge of the workpiece | work 2 by receiving the reflected light from the light projection part which projects a projection light beam (irradiation light) to the workpiece | work 2, and irradiation of the workpiece | work 2. An edge detection unit that receives the reflected light from the workpiece 2 and detects the height of the surface of the workpiece 2, and at a position shifted from the optical axis of the light projecting unit and the edge detection unit, The optical axis of the height detector is provided. That is, the optical axis of the objective lens 8 and the optical axis of the height detection lens 11 are configured to be different. Therefore, by detecting the height of the workpiece surface and adjusting the height of the machining head so that the workpiece surface is always within the depth of focus, the edge of the workpiece where the workpiece surface height changes, such as the chamfered portion, is also high. An edge detection device capable of measuring with high accuracy can be obtained in a small size and at low cost without requiring a driving component such as an actuator.

  At the chamfered edge, the height of the workpiece surface gradually changes. Further, as described above, in the edge detection device of the present embodiment, it is only necessary to adjust the focus so that the work surface falls within the depth of focus, and high-precision (high resolution) focus adjustment is not required. Therefore, it is not necessary to adjust the chamfered edge at high speed (frequently) with the movement of the scanning unit 3, and the height adjustment function of the processing head 1 or the scanning unit 3 provided in advance in the processing machine. By adjusting the distance between the edge detection sensor 101 and the surface of the workpiece (relative height of the edge detection sensor 101 with respect to the workpiece surface) using, the focus adjustment can be performed and the edge of the workpiece 2 can be detected. Become.

  As a result, it is not necessary to newly provide a drive component such as an actuator, and it is possible to configure a small and inexpensive device. Note that, as described above, it is only necessary to adjust the focus so that the work surface falls within the depth of focus. Therefore, it is not always necessary to adjust the height of the edge detection sensor 101 as long as the height of the light projecting unit can be adjusted. When the height of the entire edge detection sensor 101 is adjusted, the configuration of the edge detection sensor 101 can be simplified, for example, the objective lens 8 can be shared by the light projection unit and the edge detection unit, and the light projection unit, the height detection unit, The relative position is fixed, and it is easy to determine whether or not the work surface is within the depth of focus.

  When the processing head 1 or the scanning unit 3 is used for height adjustment, the processing head 1 or the scanning unit 3 needs to be moved in communication with the controller of the processing machine, which increases the response time. For this reason, in the conventional edge detection device, a driving component such as an actuator is attached, and the height is adjusted with a sufficiently fast response time with respect to the moving speed in the XY plane by the scanning unit. That is, since it is practically difficult to keep the machining head 1 moving at high speed, an actuator is essential in the conventional edge detection device. On the other hand, in the edge detection device of the present embodiment, since it is not necessary to perform focus adjustment with a quick response time, there is no need to newly provide a driving component such as an actuator, and it can be configured in a small and inexpensive manner. Become.

  Note that, as described above, the surface of the workpiece 2 before processing is generally rough, but the reflected light is reflected with respect to light irradiated from the vertical direction (direction perpendicular to the flat portion of the workpiece 2). The intensity distribution is often strong in the vertical direction, and it is desirable that the edge detection unit be configured to receive the reflected light in the vertical direction. Further, as described above, when the surface of the work 2 has a minute uneven shape, the intensity distribution with respect to the reflection angle of the reflected light varies depending on the irradiation position, but it is most efficient to receive light in the vertical direction on average. .

  As described above, in the edge detection device according to the present embodiment, the light projecting unit projects the condensed irradiation light onto the upper surface of the object to be detected from the vertical direction, and the height detection unit emits the irradiation light on the upper surface. Detects the relative height of the light projecting unit with respect to the upper surface based on the first reflected light component having the optical axis in the oblique direction with respect to the vertical direction among the diffusely reflected light that is diffusely reflected, While adjusting the relative height within a predetermined range based on the detection result of the height detection unit, the relative position when viewed from the vertical direction with respect to the detected object of the light projecting unit is moved along a predetermined path, The edge detection unit receives a second reflected light component having an optical axis different from the optical axis of the first reflected light component among the diffusely reflected light at a plurality of relative positions, and is detected based on a change in the amount of received light Because the edge of an object is detected, the height of the surface with chamfered edges changes. Respect also, small, detects edges with high accuracy at low cost.

Embodiment 2. FIG.
In the second embodiment, an example will be described in which the number of parts is reduced as compared with the first embodiment, and the cost is reduced and the size is reduced. Note that the description of the same points as those in Embodiment 1 is omitted.

  FIG. 14 is a diagram showing a configuration of the edge detection sensor 102 in the edge detection apparatus according to the second embodiment of the present invention, and is a configuration diagram of the configuration of the edge detection sensor 102 as viewed from the side (Y direction in FIG. 1). . The configuration other than the edge detection sensor 102 is the same as that in the first embodiment. In the edge detection sensor 102 of the present embodiment, the light projecting lens 5 and the light receiving lens 9 are reduced compared to the edge detection sensor 101 of the first embodiment. The divergent light emitted from the light source 4 is condensed on the surface of the workpiece 2 by the objective lens 8. In the edge detection sensor 102 according to the present embodiment, the condensing position of the light projecting portion and the positions of the edge detection light receiving element 10 and the height detection light receiving element 12 are in an imaging relationship. In the edge detection sensor 102 according to the present embodiment, the light source 4, the light projection diaphragm 6, the beam splitter 7, and the objective lens 8 constitute a light projection unit. In the edge detection sensor 102 of the present embodiment, the objective lens 8, the edge detection light receiving element 10, and the signal calculation unit 13 constitute an edge detection unit.

  Thus, if the light source 4, the objective lens 8, and the edge detection light-receiving element 10 are arranged in an imaging relationship, edge detection can be performed in the same manner as the edge detection apparatus of the first embodiment. Further, the optical axis of the height detection lens 11 is arranged at a position shifted from the optical axis position of the objective lens 8, and the condensing position of the projection beam (irradiation light) and the position of the height detection light receiving element 12 are set. If arranged in an imaging relationship, height detection is possible as in the edge detection apparatus of the first embodiment.

  The edge detection device according to the present embodiment has the same effects as those described in the first embodiment while suppressing the number of parts. That is, when the height of the workpiece surface changes, the amount of variation is detected by the height detector, and the edge is detected while moving the machining head 1 so that the height of the workpiece surface is within the depth of focus. Further, a chamfer edge can be measured with high accuracy, and a small and inexpensive edge detection device with a small number of parts can be obtained.

  In the present embodiment, the configuration in which the light projecting lens and the light receiving lens are reduced has been described. However, the edge detecting light receiving element 10 and the height detecting light receiving element 12 are related to the condensing position of the light projecting beam and the imaging relationship. Other configurations may be used.

Embodiment 3 FIG.
In the third embodiment, an example in which the width in the X direction of the sensor is reduced by folding the height detection unit to the light source side instead of the side surface of the edge detection unit will be described. FIG. 15 is a diagram showing the configuration of the edge detection sensor 103 in the edge detection apparatus according to the third embodiment of the present invention, and is a configuration diagram of the configuration of the edge detection sensor 103 as viewed from the side (Y direction in FIG. 1). . Since the light projecting unit and the edge detecting unit are the same as those in the first embodiment, description thereof is omitted. The configuration other than the edge detection sensor 103 is the same as that in the first embodiment.

  The edge detection sensor 103 according to the present embodiment uses light that has passed through a part of the objective lens 8 to detect the height of the workpiece surface. Of the light diffusely reflected on the work surface and converted into parallel light through the objective lens 8, the position shifted by the distance T in the + X direction with respect to the optical axis of the light projecting part or the edge detecting part is the optical axis center. The light is folded back in the + X direction by the beam splitter 7 and condensed on the height detection light receiving element 12 by the height detection lens 11. When the height of the workpiece surface changes, the light condensing position on the height detecting light receiving element 12 changes, so that the height of the workpiece surface can be detected.

  According to the edge detection apparatus of the present embodiment, the same effect as described in the first embodiment is obtained while realizing a reduction in size. That is, by providing the height detection lens 11 on the light projecting lens 5 side, the width in the X direction of the edge detection sensor 103 can be reduced, and when the height of the workpiece surface changes, the amount of variation is detected by the height detection unit. Chamfering edges can be detected with high accuracy by moving the machining head 1 while moving the machining head 1 so that the height of the workpiece surface is within the depth of focus, and a small and inexpensive edge detection device can be obtained. Can do. Here, for the height detection, the light shifted by the distance T in the + X direction is used. However, the light having the optical axis at a position shifted from the optical axis of the light projecting unit and the edge detecting unit may be used in the -X direction. Just do it.

Embodiment 4 FIG.
In the fourth embodiment, a configuration in which the reliability of the height detection signal is improved by providing two or more height detection units will be described. The optical axis of the height detection unit is arranged at a position shifted from the light projecting unit or the edge detection unit. The light projecting unit projects light perpendicularly (from the vertical direction) to the flat part of the work surface, and the edge detection unit mainly uses a component that diffuses and reflects perpendicularly to the flat part of the work surface. On the other hand, since the height detection unit uses a component diffused and reflected obliquely, the utilization efficiency of light incident on the height detection lens 11 is poor. Further, if the light amount distribution with respect to the reflection angle of the light diffusely reflected varies depending on the surface shape of the workpiece, it is conceivable that the height detection signal varies. This is because the height detection unit detects the height at the light receiving position on the height detecting light receiving element 12, and it is considered that the light receiving position varies if the light amount distribution with respect to the reflection angle varies.

  As shown in the present embodiment, by providing two or more height detection units, the amount of light incident on the height detection unit can be relatively increased, and the influence of variations in the light amount distribution on the reflection angle Therefore, the reliability of the height detection result can be improved. FIG. 16 is a diagram showing a configuration of the edge detection sensor 104 in the edge detection apparatus according to the fourth embodiment of the present invention. 16 is a configuration diagram (XZ sectional view) of the configuration of the edge detection sensor 104 viewed from the Y direction in FIG. 1, and the right diagram of FIG. 16 illustrates the configuration of the edge detection sensor 104 in FIG. It is the block diagram (YZ cross section) seen from the X direction in FIG. In the XZ sectional view of FIG. 16, the height detection unit is omitted, and the light projecting unit is omitted in the YZ section. The configuration other than the edge detection sensor 104 is the same as that in the first embodiment.

  The light projecting unit and the edge detecting unit in the edge detection sensor 104 of the present embodiment are the same as those in the first embodiment, but the height configured by the height detection lens 11 and the height detection light receiving element 12 is the same. The number and position of the height detectors are different. As shown in the YZ sectional view, two height detection lenses 11 are arranged so as to sandwich the objective lens 8, and a height detection light receiving element 12 is arranged at each condensing position. Providing two height detection lenses 11 increases the amount of signal that can be captured for height detection. Further, by providing the height detection lens 11 in different directions, signal variations can be suppressed.

  Therefore, the signal detection unit 13 calculates signals detected by the two height detection light-receiving elements 12, thereby improving the reliability of height detection. That is, a highly reliable height detection result can be obtained even if the amount of light received by each height detection light-receiving element 12 is diffusely reflected by the uneven shape of the workpiece surface and varies. In addition, the same effect as that described in the first embodiment is obtained.

  In the edge detection apparatus according to the present embodiment, two height detection units are provided with the objective lens 8 sandwiched between the YZ planes. However, as shown in the third embodiment, the light returned by the beam splitter 7 is used. Of these, a configuration in which two of the light projection lenses 5 are provided may be used. And it is not necessary to arrange | position the height detection part in the form which pinches | interposes a lens, and if it arrange | positions two or more in arbitrary positions, the reliability of a height detection signal can be improved. However, from the viewpoint of suppressing the influence of variations in the amount of received light, it is desirable to provide the height detection unit in a direction as far as possible. When two height detection units are provided, it is desirable to provide them in opposite directions.

Embodiment 5 FIG.
In the fifth embodiment, a method of quickly finding a position (area) to be detected and shortening the detection time by using a configuration incorporating a camera will be described. The detection time can be shortened by detecting the edge position roughly before detecting the edge with high accuracy, and appropriately setting the region to be detected with high accuracy based on this result. When an edge is detected with high accuracy using the detection path shown in FIG. 8, it is necessary to set a position that crosses the edge while moving the distance ΔX in the X direction as a detection start point. That is, if the edge detection is started from a position slightly entering the workpiece 2 from the roughly detected edge position, ΔX can be reduced and the detection time can be shortened. However, when the position of the edge detection device is away from the edge position of the workpiece 2, it is necessary to scan the workpiece 2 until the light projection beam (irradiation light) crosses the edge, and detection takes time. If a camera is incorporated in the edge detection apparatus and the region centered on the current light projection beam condensing position can be viewed as an image, a rough edge position can be quickly found by image recognition.

  FIG. 17 is a diagram illustrating the configuration of the edge detection sensor 105 in the edge detection device according to the fifth embodiment of the present invention, and is a configuration diagram of the configuration of the edge detection sensor 105 as viewed from the side (Y direction in FIG. 1). . In the edge detection sensor 105 of the present embodiment, the light projecting unit and the height detection unit are the same as those in the first embodiment, and thus the description thereof is omitted. A camera beam splitter 17 is provided between the beam splitter 7 and the light receiving lens 9, and a part of the light is folded back. Then, an image is formed on the pixel surface of the camera 16 using the camera lens 15. As the camera 16, a CCD camera or a CMOS imager is used. The beam splitter 7 has a function of turning back the light incident from one side (projecting lens 5 side) and transmitting the light incident from the other side (object lens 8 side). A part of the light incident from the objective lens 8 side is folded back to the camera lens 15 side, and the rest is transmitted to the light receiving lens 9 side. The configuration other than the edge detection sensor 105 is the same as that in the first embodiment.

  As described above, when the camera 16 is arranged, the position where the light projection beam is currently focused can be quickly determined by image processing. Also, if an edge is visible in the field of view of the image, edge measurement can be started immediately from the position near the edge, and the detection time can be shortened. In addition, if the camera 16 is used, not only a rough edge position but also a hole shape and other detection objects can be quickly found. As described above, when the camera 16 is incorporated in the edge detection sensor 105, an edge detection region can be quickly found, and an edge detection device with a fast detection time can be obtained. In addition, the same effect as that described in the first embodiment is obtained.

  In the first to fifth embodiments described above, when the height of the workpiece surface is outside the focal depth, the height of the machining head 1 is moved so that the workpiece surface falls within the focal depth. However, the scanning unit 3 that fixes the workpiece 2 may be moved in the height direction. Further, the scanning unit 3 is moved at the time of edge detection to change the relative position of the edge detection device and the workpiece 2 in the X direction and the Y direction, but the processing head 1 may be moved. In the first to fifth embodiments described above, the chamfered edge is used as an example of changing the height of the workpiece surface. However, the height of the workpiece surface changes, for example, when detecting the edge of a workpiece with a step. It goes without saying that it can be used for other cases. In the first to fifth embodiments described above, the height of the workpiece surface may be automatically adjusted within the depth of focus before starting edge detection by using the function of the height detection unit. it can.

  DESCRIPTION OF SYMBOLS 1 Processing head, 2 Workpieces, 3 Scanning part, 4 Light source, 5 Light projection lens, 6 Light emission stop, 7 Beam splitter, 8 Objective lens, 9 Light reception lens, 10 Light detection element for edge detection, 11 Height detection lens, 12 light detection element for height detection, 13 signal calculation unit, 14 mounting jig, 15 lens for camera, 16 camera, 17 beam splitter for camera, 101-105 edge detection sensor.

Claims (7)

A light projecting unit that projects the collected irradiation light on the upper surface of the object to be detected from the vertical direction;
Relative height of the light projecting unit with respect to the upper surface based on a first reflected light component having an optical axis obliquely with respect to the vertical direction of the diffuse reflected light obtained by diffusely reflecting the irradiation light on the upper surface. A height detector for detecting
Based on the detection result of the height detection unit, the relative height is adjusted within a predetermined range, and the relative position when the light projecting unit is viewed from the vertical direction with respect to the detected object is a predetermined path. A drive unit moved by
The object to be detected is received based on a change in the amount of received light by receiving a second reflected light component having an optical axis different from the optical axis of the first reflected light component of the diffusely reflected light at the plurality of relative positions. An edge detection device comprising: an edge detection unit that detects an edge of the edge detection device.   The edge detection apparatus according to claim 1, wherein the optical axis of the second reflected light component is in a vertical direction.   The edge detection apparatus according to claim 1, wherein the predetermined range is within a range of a focal depth of the irradiation light.   The said height detection part detects the said relative height based on direction of the optical axis of a said 1st reflected light component, The any one of Claims 1-3 characterized by the above-mentioned. Edge detection device.   5. The edge detection device according to claim 1, wherein the first reflected light component is a part of the second reflected light component. 6.   The edge detection device according to claim 1, comprising a plurality of the height detection units.   7. The edge detection according to claim 1, further comprising a camera that images the object to be detected, wherein a start point of the predetermined path is determined based on an imaging result of the camera. apparatus.

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