Method for measuring the center position of the rotating shaft of a machine tool

Abstract

A tool (3) is mounted on the spindle (18), and a detection unit (20) capable of non-contactly detecting the position of the tool (3) is set on the rotary table (13). The tool (3) and the rotary table (13) are divided into specified angular positions about the object being measured by the C-axis, which is the axis of rotation. The detection action of detecting the position of the tool (3) relative to the rotary table (13) is repeatedly performed at each angular position using the detection unit (20). The center position of the C-axis is calculated based on the position of the tool (3) at each angular position detected by the multiple detection actions.

Description

Technical Field

[0001] This invention relates to a method for measuring the center position of a rotating shaft of a machine tool. Background Technology

[0002] In machine tools, a tool mounted on a spindle processes a workpiece placed on a worktable. During processing, by moving the tool and workpiece in three dimensions in the X, Y, and Z axes, any three-dimensional shape can be machined onto the workpiece.

[0003] To increase machining freedom, some machine tools include rotary axes that allow the tool to rotate around the translation axes, in addition to the translation axes in the XYZ directions. Examples of these additional rotary axes include an A-axis for rotation around the X-axis, a B-axis for rotation around the Y-axis, and a C-axis for rotation around the Z-axis. A multi-axis controlled machine tool can be, for example, a 5-axis machine tool with added A-axis and C-axis control for the X, Y, and Z axes.

[0004] In the aforementioned multi-axis controlled machine tools, to improve machining accuracy, it is necessary to minimize the positional error of the translation axis and minimize the angular error and positional accuracy of the rotation center of the rotation axis. Specifically, to suppress the decrease in machining accuracy caused by errors in the center position of the rotation axis, the center position of the rotation axis is measured and used as a parameter for correction control during machining (see Patent Document 1).

[0005] In Patent Document 1, as a method for measuring the center position of a rotating shaft, a target ball, which serves as a reference calibration gauge, is fixed to the worktable instead of a workpiece, and a contact probe is mounted on the spindle instead of a tool. The rotating shaft to be measured is divided into multiple angles, and the center position of the target ball is measured by contacting the contact probe with the target ball at each angle position. The center position of the rotating shaft is calculated based on the measured values ​​at multiple angle positions.

[0006] In particular, in Patent Document 1, in order to measure the center position of the rotating shaft with high accuracy even in the case of a machine in which the range of motion of the translation axis is structurally limited, the contact action between the contact probes at multiple angular positions of the rotating shaft and the target ball is performed only within the range of motion of the translation axis. No contact action is performed in the range where the movement is limited, and the center position of the rotating shaft is measured by calculation.

[0007] On the other hand, a tool position detection method was developed that can measure all error amounts in the X, Y, and Z directions using only one measuring device, even when the tool and measuring device interfere with each other and the indexing range of the rotary axis (4th axis, 5th axis) is greatly limited (Patent Document 2).

[0008] In Patent Document 2, the tool positioning error in the X, Y, and Z directions is calculated based on the error in two directions between the lowest point of the tool on the rotation axis of the rotary table and the tool center point obtained by measuring two or more points on the outer periphery of the tool in a plane orthogonal to the rotation axis of the rotary table.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: Japanese Patent Application Publication No. 2019-152574

[0012] Patent Document 2: Japanese Patent Application Publication No. 2020-28922 Summary of the Invention

[0013] The problem that the invention aims to solve

[0014] The measurement method described in Patent Document 1 enables high-precision measurement of the center position of the rotating shaft, even in machine tools where the range of motion of the translation axis is limited.

[0015] However, in the measurement method of Patent Document 1, in order to detect the position of the target ball, a contact probe is mounted on the spindle instead of a cutting tool.

[0016] Therefore, the working machine at the time of measurement is not in the actual machining state with the tool mounted on the spindle. The measured center position of the rotating shaft is different from the center position during machining, which has a limit to the measurement accuracy.

[0017] Furthermore, in working machines where a contact probe cannot be mounted on the spindle, there is a problem that the measurement method described in Patent Document 1 cannot be used.

[0018] On the other hand, Patent Document 2 suggests several methods for determining the error in both directions of the tool's center point. However, the tool type is not limited to ball end mills, and the premise is that the tool tip is treated as a "perfect circle." This method cannot be applied to tools with different tip shapes, making it difficult to measure the center position with high precision. Therefore, there is a requirement to be able to measure the center position of the rotation axis with high precision through simple calculations, even for tools with a wide variety of tip shapes.

[0019] The purpose of this invention is to provide a method for measuring the center position of a rotating shaft in a working machine that can measure the center position of the rotating shaft with high precision through simple calculation without using a contact probe.

[0020] Another objective of this invention is to provide a method for measuring the center position of a rotating shaft in a working machine that can accurately measure the center position of the rotating shaft through simple calculations, even for tools with a wide variety of front-end shapes.

[0021] Methods used to solve problems

[0022] The method for measuring the center position of the rotating shaft of a machine tool according to the present invention is characterized in that a tool is mounted on the spindle, and a detection unit capable of non-contactly detecting the position of the tool is set on the worktable; regarding the rotating shaft of the object to be measured, the tool and the worktable are divided into predetermined angular positions, and the detection action of using the detection unit to detect the position of the tool relative to the worktable at each angular position is repeatedly performed; based on the position of the tool at each angular position detected by the multiple detection actions, the center position of the rotating shaft is calculated.

[0023] In this invention, by repeatedly performing the detection action using a non-contact detection unit, and by performing geometric calculations based on the tool's position at each angular location, the center position of the rotating shaft can be measured with high precision.

[0024] During measurement, machining tools can be mounted on the spindle of the machine tool, and the spindle can be rotated and heated before measurement, allowing measurement to be performed under the same conditions as during machining. Furthermore, it can be widely used on machine tools where a contact probe cannot be mounted on the spindle.

[0025] Therefore, according to the present invention, a method for measuring the center position of a rotating shaft in a working machine can be provided, which can measure the center position of the rotating shaft with high accuracy through simple calculation without using a contact probe.

[0026] Furthermore, in this invention, as long as the position and orientation of the detection unit relative to the worktable can be determined with high precision, the rotation center of the rotating axis can be calculated with fewer calculations. However, even if the position and orientation of the detection unit relative to the worktable cannot be determined with high precision, the position of the tool at each angle position can be determined with high precision by reducing the position of the tool tip through geometric calculations by detecting the position of the tool at each angle position through multiple detection actions.

[0027] In the method for measuring the center position of the rotating shaft of the working machine of the present invention, it is preferable that the detection unit is capable of non-contactly detecting that the front end of the tool is at a specific position of the detection unit; in the detection operation, the spindle and the worktable are moved relative to each other to divide the tool and the worktable into predetermined angular positions, and the relative positions of the spindle and the worktable are adjusted at each angular position so that the tool comes to the specific position of the detection unit. In this state, the position of the tool relative to the worktable at each angular position is detected according to the relative position of the spindle and the worktable.

[0028] In this invention, when the detection unit is used to detect the position of a tool relative to the worktable as a detection action, the tool's position can be detected either within the detection unit itself or as a tool positioning fixture, obtaining control position data from the machine's control device. That is, by moving the machine under the control of the control device, the spindle is moved, positioning the tool at a specific position on the detection unit. In this state, the tool's position can be obtained by referring to the spindle position data in the machine's control device. This specific position can be the center position of the tool detection area using the detection unit, etc.

[0029] In the method for measuring the center position of the rotating shaft of the working machine of the present invention, the detection unit capable of detecting the radial position of the worktable of the tool may be used; the tool and the worktable are divided into four angular positions: two angular positions opposite each other in the first direction across the rotating shaft, and two angular positions opposite each other in the second direction intersecting the first direction across the rotating shaft; the detection operation is performed at each angular position to detect the radial position of the worktable of the tool; a first straight line passing through the midpoint of the line segment connecting the positions of the tool detected at the two angular positions opposite each other in the first direction and intersecting the first direction, and a second straight line passing through the midpoint of the line segment connecting the positions of the tool detected at the two angular positions opposite each other in the second direction and intersecting the second direction are calculated; the intersection of the first straight line and the second straight line is measured as the center position of the rotating shaft.

[0030] In this invention, as a detection unit capable of detecting the position of a tool in the radial direction of a worktable, an image sensor that detects the position of the tool in an image by detecting images from the side of the tool can be used and is positioned circumferentially toward the worktable.

[0031] As four angular positions opposite each other across the rotation axis, for example, the 0-degree and 180-degree positions of the worktable can be set as two angular positions opposite each other in the first direction, and the 90-degree and 270-degree positions can be set as two angular positions opposite each other in the second direction.

[0032] According to this invention, the range of inference for the center position that cannot be determined by detection actions at 0 degrees and 180 degrees can be reduced by the position of the tool obtained by detection actions at 90 degrees and 270 degrees, thereby determining the correct center of the rotating shaft. The center position of the rotating shaft can be measured with high precision using detection actions at a total of four angular positions.

[0033] In the method for measuring the center position of the rotating shaft of the machine tool of the present invention, the detection unit capable of detecting the position of the tool along the surface of the worktable may be used; the tool and the worktable are divided into two angular positions opposite each other across the rotating shaft, and the detection action is performed at each angular position to detect the position of the tool along the surface of the worktable; the midpoint of the line segment connecting the positions of the tool in the two detection actions is calculated, and the midpoint is measured as the center position of the rotating shaft.

[0034] In this invention, as a detection unit capable of detecting the position of a tool along the surface of a worktable, a detection unit capable of detecting the radial and circumferential positions of the tool on the worktable can be used; more specifically, an image sensor system with an autofocus function can be arranged circumferentially on the worktable, the position of the tool in an image from the side of the tool is set as the radial position, and the position of the tool in the depth direction of the image detected by the autofocus function is set as the circumferential position.

[0035] These can be two angular positions opposite each other across the rotation axis, such as the 0-degree position and the 180-degree position of the worktable.

[0036] According to this invention, the center position of a rotating shaft can be measured with high precision through a simple operation such as detection actions at two angular positions.

[0037] In the method for measuring the center position of the rotating shaft of the working machine of the present invention, the detection unit capable of detecting the radial position of the worktable of the tool may be used; the tool and the worktable may be indexed into multiple angular positions within a specified angular range centered on the rotating shaft, and the detection action may be performed at each angular position to detect the radial position of the worktable of the tool; the position of the tool obtained in multiple detection actions may be plotted, and the center position of the rotating shaft may be calculated by approximate calculation.

[0038] In this invention, even when the detection action cannot be performed within a certain angular range around the rotation axis due to the limitations of the machine's construction, by repeatedly performing the detection action within a limited angular range other than that angular range, the candidate position of the rotation axis center can be plotted as, for example, an arc shape, and the center position can be determined by approximate calculations such as the least squares method.

[0039] In the method for measuring the center position of the rotating shaft of the working machine of the present invention, it is preferable that the detection unit has a fixing mechanism relative to the worktable.

[0040] In this invention, the detection unit mounted on the worktable needs to maintain its position relative to the worktable during the detection operation at various angular positions. When the worktable is facing upwards, simply placing the unit on the worktable and using friction to restrict its movement is sufficient. When the worktable is not facing upwards, it is preferable to use other fixing mechanisms to prevent the detection unit from falling off the worktable.

[0041] As the fixing mechanism, a mechanism that is easy to assemble and disassemble is preferred. For example, it can be fixed by magnetic adsorption, adhesion by adhesive sheets or adhesives, or mechanical fixing such as clamps. Since the detection unit is non-contact, there is basically no movement due to contact with the tool, and it is not necessary to firmly fix the detection unit relative to the worktable.

[0042] In the method for measuring the center position of the rotating shaft of the working machine of the present invention, it is preferable that the detection unit has an illumination unit that illuminates a parallel light beam and an imaging unit that detects the parallel light beam; and the front end position of the tool disposed in the parallel light beam is detected based on the image detected by the imaging unit.

[0043] In this invention, as the irradiation unit, a structure that forms a parallel beam using a point light source and a focal stop lens, a structure that forms a parallel beam using light sources arranged in a straight line, or a structure that simulates forming a parallel beam by oscillating the beam in parallel can be appropriately used.

[0044] In this invention, the preferred imaging unit is an image detector that can output data of the captured image and perform image processing, such as a CCD (Charge Coupled Device) type camera.

[0045] In this invention, when detecting the position of the front end of a tool positioned in a parallel beam based on an image detected by a camera, the following software can be used: by performing existing image processing on the image detected by the camera, detecting the shadow of the tool positioned in the parallel beam, and calculating the position of the front end of the tool by calculating its center position based on the contour of the tool's front end through edge detection.

[0046] In this invention, the position of the tool's tip can be detected with high precision and without contact by performing optical detection.

[0047] Furthermore, during position detection, the tool can be positioned simply by placing the tip of the tool into the parallel beam between the illumination unit and the camera unit, making the detection operation relatively easy.

[0048] In the method for measuring the center position of the rotating shaft of the working machine of the present invention, it is preferable that the image is detected by the camera unit while the tool is rotated relative to the camera unit; the outline of the tool is detected based on the image; the central axis of the tool is detected based on the symmetry of the outline; and the intersection of the central axis and the outline is detected as the front end position of the tool.

[0049] In this invention, the central axis of the tool can be detected by utilizing the linear symmetry of its contour. Furthermore, the position of the tool's tip can be determined by finding the intersection of the detected central axis and the tool's contour. There are no restrictions on the shape of the tool's tip, allowing for the determination of the tip position for tools with a wide variety of tip shapes. Moreover, the determination of the tip position can be achieved solely through geometric calculations on the tool's image, enabling high-precision measurement of both the tip position and the center position of the rotation axis through simple calculations.

[0050] In the method for measuring the center position of the rotating shaft of the working machine of the present invention, it is preferable to detect the intersection of the central axis and the contour as the front end position of the tool; set a pair of parallel lines at a predetermined distance on both sides of the central axis, and set an auxiliary contour line that passes through the intersection of the pair of parallel lines and the contour and is orthogonal to the central axis; and detect the intersection of the central axis and the auxiliary contour line as the front end position of the tool.

[0051] In this invention, for tools with multiple protrusions at the front end or with an offset front end, where the shape of the front end becomes unclear during rotation, the front end position can be determined based on the center by setting an auxiliary contour line. Thus, the front end position and the center position of the rotation axis of tools with various front end shapes can be measured with high precision through simple calculations.

[0052] In the method for measuring the center position of the rotating shaft of the working machine of the present invention, a plurality of cross-sections that cross the contour in the extension direction of the tool can be set, and two intersection points and the midpoint of the two intersection points with each cross-section are detected. The straight line passing through the midpoint of each cross-section is taken as the central axis of the tool.

[0053] In this invention, the correct central axis (axis of rotational symmetry) of the tool can be detected using the tool's extension direction (the tool's orientation, approximate axial direction). Then, by using geometric calculations of multiple cross-sections, the position of the tool's tip and the center position of the rotation axis can be easily and accurately measured.

[0054] In the method for measuring the center position of the rotating shaft of the working machine of the present invention, the shape of one side of the profile relative to the extension direction of the tool can be detected as a reference pattern, and a symmetrical pattern that is consistent with the shape of the reference pattern is detected based on the profile. The straight line passing through the middle of the reference pattern and the symmetrical pattern is taken as the central axis of the tool.

[0055] In this invention, the correct central axis (axis of rotational symmetry) of the tool can be detected using the tool's extension direction (the tool's orientation, approximate axial direction). Then, through pattern recognition on the image, the position of the tool's tip and the center position of the rotation axis can be easily and accurately measured.

[0056] According to the present invention, a method for measuring the center position of a rotating shaft in a working machine is provided, which enables high-precision measurement of the center position of a rotating shaft through simple calculation without using a contact probe. Furthermore, a method for measuring the center position of a rotating shaft in a working machine is also provided, which enables high-precision measurement of the center position of a rotating shaft through simple calculation for tools with a wide variety of front end shapes. Attached Figure Description

[0057] Figure 1 This is a perspective view of the working machine according to the first embodiment of the present invention.

[0058] Figure 2 This is a perspective view of the detection unit of the first embodiment described above.

[0059] Figure 3 This is a schematic diagram illustrating the detection unit of the first embodiment described above.

[0060] Figure 4 This is a perspective view illustrating the detection operation of the first embodiment described above.

[0061] Figure 5 This is a schematic diagram showing the front end of the tool during the detection operation of the first embodiment described above.

[0062] Figure 6 This is a schematic diagram illustrating the detection operation of the first embodiment described above.

[0063] Figure 7A This is a schematic diagram illustrating the C-axis position measurement operation of the first embodiment described above.

[0064] Figure 7B This is a schematic diagram illustrating the C-axis position measurement operation of the first embodiment described above.

[0065] Figure 7C This is a schematic diagram illustrating the C-axis position measurement operation of the first embodiment described above.

[0066] Figure 8A This is a schematic diagram illustrating the C-axis position measurement operation of the first embodiment described above.

[0067] Figure 8B This is a schematic diagram illustrating the C-axis position measurement operation of the first embodiment described above.

[0068] Figure 8C This is a schematic diagram illustrating the C-axis position measurement operation of the first embodiment described above.

[0069] Figure 9 This is a schematic diagram illustrating the C-axis position measurement operation of the first embodiment described above.

[0070] Figure 10A This is a schematic diagram illustrating the C-axis position measurement operation according to the second embodiment of the present invention.

[0071] Figure 10B This is a schematic diagram illustrating the C-axis position measurement operation according to the second embodiment of the present invention.

[0072] Figure 10C This is a schematic diagram illustrating the C-axis position measurement operation according to the second embodiment of the present invention.

[0073] Figure 11A This is a schematic diagram illustrating the C-axis position measurement operation according to the third embodiment of the present invention.

[0074] Figure 11B This is a schematic diagram illustrating the C-axis position measurement operation according to the third embodiment of the present invention.

[0075] Figure 11C This is a schematic diagram illustrating the C-axis position measurement operation according to the third embodiment of the present invention.

[0076] Figure 12A This is a schematic diagram illustrating the C-axis position measurement operation of the third embodiment described above.

[0077] Figure 12B This is a schematic diagram illustrating the C-axis position measurement operation of the third embodiment described above.

[0078] Figure 12C This is a schematic diagram illustrating the C-axis position measurement operation of the third embodiment described above.

[0079] Figure 13 This is a schematic diagram illustrating a variation of the first to third embodiments described above.

[0080] Figure 14 This is a schematic diagram illustrating the A-axis position measurement operation according to the fourth embodiment of the present invention.

[0081] Figure 15AThis is a schematic diagram illustrating the A-axis position measurement operation of the fourth embodiment described above.

[0082] Figure 15B This is a schematic diagram illustrating the A-axis position measurement operation of the fourth embodiment described above.

[0083] Figure 16 This is a schematic diagram illustrating the A-axis position measurement operation of the fourth embodiment described above.

[0084] Figure 17 This is a schematic diagram illustrating the A-axis position measurement operation according to the fifth embodiment of the present invention.

[0085] Figure 18 This is a schematic diagram illustrating the A-axis position measurement operation of the fifth embodiment described above.

[0086] Figure 19A This is a schematic diagram illustrating the A-axis position measurement operation of the fifth embodiment described above.

[0087] Figure 19B This is a schematic diagram illustrating the A-axis position measurement operation of the fifth embodiment described above.

[0088] Figure 20 This is a schematic diagram illustrating the A-axis position measurement operation of the fifth embodiment described above.

[0089] Figure 21A This is a schematic diagram illustrating the A-axis position measurement operation according to the sixth embodiment of the present invention.

[0090] Figure 21B This is a schematic diagram illustrating the A-axis position measurement operation according to the sixth embodiment of the present invention.

[0091] Figure 21C This is a schematic diagram illustrating the A-axis position measurement operation according to the sixth embodiment of the present invention.

[0092] Figure 22 This is a schematic diagram illustrating a variation of the A-axis position measurement operation of the sixth embodiment described above.

[0093] Figure 23A This is a schematic diagram illustrating a variation of the A-axis position measurement operation of the sixth embodiment described above.

[0094] Figure 23B This is a schematic diagram illustrating a variation of the A-axis position measurement operation of the sixth embodiment described above.

[0095] Figure 23C This is a schematic diagram illustrating a variation of the A-axis position measurement operation of the sixth embodiment described above.

[0096] Figure 24AThis is a schematic diagram illustrating the tool tip position detection process described in the seventh embodiment above.

[0097] Figure 24B This is a schematic diagram illustrating the tool tip position detection process described in the seventh embodiment above.

[0098] Figure 24C This is a schematic diagram illustrating the tool tip position detection process described in the seventh embodiment above.

[0099] Figure 25A This is a schematic diagram illustrating the tool tip position detection process with different orientations in the seventh embodiment described above.

[0100] Figure 25B This is a schematic diagram illustrating the tool tip position detection process with different orientations in the seventh embodiment described above.

[0101] Figure 26A This is a schematic diagram illustrating the tool tip position detection process of the eighth embodiment described above.

[0102] Figure 26B This is a schematic diagram illustrating the tool tip position detection process of the eighth embodiment described above.

[0103] Figure 27A This is a schematic diagram showing the shape of the tool tip and its image according to the ninth embodiment described above.

[0104] Figure 27B This is a schematic diagram showing the shape of the tool tip and its image according to the ninth embodiment described above.

[0105] Figure 27C This is a schematic diagram showing the shape of the tool tip and its image according to the ninth embodiment described above.

[0106] Figure 28A This is a schematic diagram illustrating the tool tip position detection process of the ninth embodiment described above.

[0107] Figure 28B This is a schematic diagram illustrating the tool tip position detection process of the ninth embodiment described above. Detailed Implementation

[0108] [First Embodiment]

[0109] exist Figure 1 In the machine tool 1, a movable worktable 12 and a rotary worktable 13 are provided on the upper surface of the bed 11.

[0110] The movable worktable 12 is supported and moves freely along the upper surface of the bed 11. It can be positioned to a specified position in the X-axis direction by moving via an X-axis moving mechanism (not shown) formed on the bed 11.

[0111] The rotary table 13 is rotatably mounted on the upper surface of the movable table 12. By rotating the C-axis rotation mechanism (not shown) formed on the movable table 12, it can be positioned at a specified angle around the C-axis.

[0112] The workpiece 2, which is to be processed, is fixed on the upper surface of the rotary table 13.

[0113] The machine tool 1 has a portal-shaped column 14 on the upper surface of the bed 11.

[0114] The column 14 is formed in a gate shape to span the movement path of the movable worktable 12 in the X-axis direction. The spindle head 17 is supported on the column 14 via the saddle 15 and the slide 16.

[0115] The saddle 15 is supported and can move freely along the horizontal bar of the column 14. It can be positioned to a specified position in the Y-axis direction by moving via the Y-axis moving mechanism (not shown) provided on the column 14.

[0116] The slide 16 is supported and can be raised and lowered freely along the vertical surface of the saddle 15. It can be positioned to a specified position in the Z-axis direction by moving via the Z-axis moving mechanism (not shown) provided on the saddle 15.

[0117] The spindle head 17 is rotatably supported by the lower surface of the slide 16, and can be positioned at a specified angle around the A-axis by rotating via the A-axis rotation mechanism (not shown) formed on the slide 16.

[0118] The spindle 18 is rotatably supported on the spindle head 17, and the tool 3 is mounted on the front end of the spindle 18.

[0119] The spindle 18 rotates via a motor mounted on the spindle head 17, enabling the tool 3 to rotate at the specified speed and torque required for the cutting of the workpiece 2.

[0120] The machine tool 1, through five-axis control (X-axis movement of the movable worktable 12, Y-axis movement of the saddle 15, Z-axis movement of the slide 16, plus C-axis rotation of the rotary worktable 13 and A-axis rotation of the spindle head 17), can perform various cutting operations on the workpiece 2. A CNC (Computer Numerical Control) type control device 9 is connected to the machine tool 1 to perform these motion controls.

[0121] In such a machine tool 1, the center position of the rotation axis of the C-axis of the rotary table 13 is measured in the following order.

[0122] exist Figure 2 In this embodiment, in order to measure the center position of the C-axis of the working machine 1, a detection unit 20 is provided on the rotary table 13.

[0123] exist Figure 3 In the process, the detection unit 20 has a housing 21, which can be attached to and detached from the surface of the rotary table 13 via feet 22 at both ends of the housing 21. The feet 22 have fixing mechanisms such as adhesive, magnets or suction cups, and are fixed to the surface of the rotary table 13 to prevent misalignment.

[0124] The housing 21 has an opening 23 on the upper surface of the middle section. Inside the housing 21, an illumination unit 24 is provided on one side through the opening 23, and a focal length lens 25, a CCD camera 26 serving as an image capture unit and a processing unit 27 are provided on the opposite side.

[0125] The illumination unit 24 can irradiate a parallel beam 28 toward the focal stop lens 25 through the opening 23.

[0126] The parallel beam 28 is focused by the focal stop lens 25 and photographed by the CCD camera 26.

[0127] The CCD camera 26, which serves as the imaging unit, detects a cross-sectional image of the parallel beam 28 based on the incident focused beam. Here, if the object 29 to be detected is placed at the opening 23, a portion of the parallel beam 28 is blocked, forming a shadow 281.

[0128] The arithmetic unit 27 processes the detection image of the CCD camera 26, and by measuring the width and height of the shadow 281 presented in the detection image, it can detect the width and height of the detection object 29 without contact.

[0129] exist Figure 4 In this process, by inserting the front end of the tool 3 into the opening 23 of the detection unit 20, the front end of the tool 3 is positioned in the parallel beam 28 as the object to be detected 29, and the position of the front end of the tool 3 can be detected.

[0130] The detection unit 20 is positioned so that the illumination unit 24 and the CCD camera 26 face each other along the circumference of the rotating stage 13, so that the parallel beam 28 is in the circumference of the rotating stage 13 (orthogonal to the radial direction of the rotating stage 13).

[0131] The position of the detection unit 20 only needs to be located away from the center of the rotary table 13; precise positioning is not required. Furthermore, the orientation of the detection unit 20 does not need to be the same as the direction in which the parallel beam 28 is correctly aligned with the circumference of the rotary table 13. This is because, even if there are incorrect components, these components will be canceled out during calculations at the opposing positions (angular positions A0 and A180, angular positions A90 and A270, as described later).

[0132] When the tool 3 is introduced into the detection unit 20, its position is adjusted so that the front end of the tool 3 is positioned relative to the detection image of the CCD camera 26. Figure 5 The center of the detected image 261).

[0133] exist Figure 5 In the image 261 detected by the CCD camera 26, the shadow 281 of the front end of the tool 3 is shown.

[0134] In the detected image 261, the coordinates (Tv, Th) of the front end position 283 of the tool 3 can be correctly calculated based on the outline 282 of the shadow 281.

[0135] In the coordinates (Tv, Th) detected by the detection image 261, the vertical coordinate Tv corresponds to the Z-axis coordinate of the machine tool 1. On the other hand, the horizontal coordinate Th is the radial position Rc (radial distance) of the tool 3 relative to the center of the rotary table 13, corresponding to the angular position of the rotary table 13 projected onto the X-axis and Y-axis coordinates of the machine tool 1. For example, when the rotary table 13 is in Figure 7A When the angle position is A0, the detection image 261 intersects the X-axis of the machine tool 1, and the coordinate Th becomes the Y-axis coordinate Ty of the machine tool 1. When the rotary table 13 is at... Figure 8A When the angle position is A90, the detection image 261 intersects the Y-axis of the working machine 1, and the coordinate Th becomes the X-axis coordinate Tx of the working machine 1.

[0136] When calculating the coordinates (Tv, Th) of the front end position 283 of tool 3, the front end position detection of tool 3 can be performed either by image processing of the detected image 261 in the calculation unit 27, or by using the detection unit 20 as a positioning fixture for tool 3 to obtain the position data of the machine tool 1 as the front end position of tool 3. In this case, the detection processing of the front end position of tool 3 can be performed not only by the calculation unit 27 provided in the detection unit 20, but also by image detection performed by the CCD camera 26 in the detection unit 20. The processing of the detected image 261 and the detection of the front end position of tool 3 are performed by the control device 9 of the machine tool 1.

[0137] exist Figure 6 In the machine tool 1, the control device 9 has an action control unit 91 for controlling the movement of the aforementioned axes, and a tool position detection unit 92 for detecting the position of the front end of the tool 3 by performing image processing on the detection image 261 obtained from the detection unit 20.

[0138] During the detection process, the machine tool 1 is activated by the motion control unit 91, causing the spindle 18 to move and guide the tool 3 into the opening 23 of the detection unit 20. The relative positions of the spindle 18 and the rotary table 13 are adjusted so that the tip of the tool 3 reaches a specific position in the detection unit 20. In this state, the tool position detection unit 92 can obtain the position data of the spindle 18 (the Z-axis coordinates, X-axis coordinates, and Y-axis coordinates of the machine tool 1) from the motion control unit 91, calculate the coordinates Tv and Th in the detection image 261, and use them as the tip position of the tool 3.

[0139] As a specific position, the center position of the opening 23 of the detection unit 20, which serves as the tool detection area, can be used. To position the front end of the tool 3 at a specific position, a mark indicating the specific position can be displayed on the detection image 261 of the CCD camera 26. Alternatively, the center position of the detection image 261 of the CCD camera 26 can be used as the specific position, and the specific position can be determined solely by visual inspection. This is because even if the specific position is incorrect, the incorrect component is canceled out during calculations at the opposing positions (angle positions A0 and A180, angle positions A90 and A270, as described later).

[0140] In this embodiment, the detection unit 20 described above is used to measure the center position of the C-axis of the working machine 1 in the following order.

[0141] exist Figure 7A First, the rotary table 13 is set to angular position A0, and the detection unit 20 is placed at a position away from the center of the rotary table 13.

[0142] Assume the angular position A0 of the rotary table 13 is such that the optical axis of the CCD camera 26 is along the X-axis of the machine tool 1. However, the angular position A0 can be any angle.

[0143] Once the detection unit 20 is set, the spindle 18 (refer to...) Figure 1 The tool 3 is lowered from above the rotary table 13 and guided into the opening 23 of the detection unit 20. Then, the detection unit 20 records the position P0 (Tx0, Ty0) of the tool 3 at the angular position A0.

[0144] Next, after the tool 3 is raised and pulled out from the detection unit 20, the rotary table 13 is rotated 180 degrees from the angular position A0 while the detection unit 20 is still in place. This is set as the angular position A180, which is opposite to the angular position A0 on the first direction D1 across the C-axis.

[0145] exist Figure 7BIn the process, with the rotary table 13 at angle position A180, the tool 3 is again imported into the detection unit 20. Then, the detection unit 20 records the position P180 (Tx180, Ty180) of the front end of the tool 3 at angle position A180.

[0146] exist Figure 7C Once the positions of tool 3 at angular position A0 and angular position A180 are obtained, P0 and P180 respectively, the calculation unit 27 calculates the first straight line L1 that passes through the center of the C-axis and intersects the first direction D1. Specifically, the position P0 of tool 3 at angular position A0 and the front end position P180 of tool 3 at angular position A180 are connected by a line segment L01, and the straight line that passes through the midpoint and intersects the first direction D1 is set as the first straight line L1.

[0147] Once passed Figures 7A to 7C The detection action yields the first straight line L1, and the second straight line L2 is calculated in the same order.

[0148] exist Figure 8A In this process, the detection unit 20 and the rotary table 13 are set to angular position A90 (the angular position after rotating 90 degrees from angular position A0), and the tool 3 is inserted into the opening 23 of the detection unit 20. Then, the detection unit 20 records the front end position P90 (Tx90, Ty90) of the tool 3 at angular position A90.

[0149] exist Figure 8B In the same operation, the detection unit 20 and the rotary table 13 are set to an angular position A270 opposite to the angular position A90 in the second direction D2 (intersecting the first direction D1) across the C axis. The detection unit 20 records the front end position P270 (Tx270, Ty270) of the tool 3 at the angular position A270.

[0150] exist Figure 8C Once the positions of the tool 3's front end P90 and P270 at angular positions A90 and A270 are obtained, the calculation unit 27 calculates the second straight line L2 that passes through the center of the C-axis and intersects the second direction D2. Specifically, the tool 3's front end position P90 at angular position A90 and the tool 3's front end position P270 at angular position A270 are connected by a line segment L02, and the straight line passing through its midpoint and intersecting the second direction D2 is defined as the second straight line L2.

[0151] exist Figure 9Once the first straight line L1 and the second straight line L2 are obtained, the calculation unit 27 calculates the intersection point Pc of the first straight line L1 and the second straight line L2. As a result, the possible range of the C-axis center position is limited to point 1 of the intersection point Pc, and the correct C-axis center position of the working machine 1 can be measured.

[0152] According to this embodiment, the following effects are achieved.

[0153] In this embodiment, a tool 3 is mounted on the spindle 18, and a detection unit 20 capable of non-contactly detecting the position of the tool 3 is set on the rotary table 13. The tool 3 and the rotary table 13 are divided into predetermined angular positions (A0, A90, A180, A270) about the C-axis of the object being measured. The detection action of detecting the position of the tool 3 relative to the rotary table 13 (P0, P90, P180, P270) at each angular position by the detection unit 20 is repeatedly performed. Based on the position of the tool 3 at each angular position detected in the four detection actions, the center position (Pc) of the C-axis is calculated.

[0154] In this embodiment, by repeatedly performing the detection action using the non-contact detection unit 20 four times, and performing geometric calculations based on the position of the tool 3 at each angular position, the center position (Pc) of the C-axis can be measured with high precision.

[0155] During measurement, a machining tool 3 can be mounted on the spindle 18 of the machine tool 1. Before measurement, the spindle 18 is rotated to heat it up, and the measurement is performed under the same conditions as during machining. In addition, it can also be widely used for machine tools 1 where a contact probe cannot be mounted on the spindle 18.

[0156] Therefore, according to this embodiment, the center position of the C-axis can be measured with high accuracy through simple calculations without using a contact probe.

[0157] In this embodiment, a detection unit 20 capable of detecting the radial position of the rotary table 13 of the tool 3 is used. The tool 3 and the rotary table 13 are indexed into four angular positions: two angular positions A0 and A180 opposite each other on the first direction D1 across the C-axis, and two angular positions A90 and A270 opposite each other on the second direction D2 intersecting the first direction D1 across the C-axis. The radial position (P0, P90, P180, P270) of the rotary table 13 of the tool 3 is detected by performing detection actions at each angular position. Calculate the first straight line L1 that passes through the midpoint of the line segment L01 that connects the positions P0 and P180 of the tool 3 detected at two opposite angular positions A0 and A180 on the first direction D1 and intersects the first straight line D1, and the second straight line L2 that passes through the midpoint of the line segment L02 that connects the positions P90 and P270 of the tool 3 detected at two opposite angular positions A90 and A270 on the second direction D2 and intersects the second direction D2. Measure the intersection point Pc of the first straight line L1 and the second straight line L2 as the center position of the C-axis.

[0158] Therefore, as the detection unit 20 in this embodiment, it is sufficient to detect the position of the tool 3 radially relative to the rotary table 13. This can be achieved by utilizing the detection image 261 (refer to) that detects the side view of the tool 3. Figure 5 The image sensor (illumination unit 24 and CCD camera 26) detects the position of tool 3 on the image and refers to... Figure 3 The structure is arranged circumferentially toward the rotary table 13.

[0159] According to this embodiment, the inference range (straight line L1) of the C-axis center position that cannot be determined by the detection action at the 0-degree and 180-degree angular positions A0 and A180 can be reduced by the position (straight line L2) of the tool 3 obtained by the detection action at the 90-degree and 270-degree angular positions A90 and A270, thus determining the correct C-axis center. The C-axis center position can be measured with high precision by the detection action at a total of 4 angular positions (A0, A90, A180, A270).

[0160] In this embodiment, the detection unit 20 includes: an illumination unit 24 that illuminates a parallel beam 28; an imaging unit (focal stop lens 25 and CCD camera 26) that detects the parallel beam 28; and a calculation unit 27 that detects the position of the front end of the tool 3 disposed in the parallel beam 28 based on the detection image 261; detects the shadow 281 of the tool 3 disposed in the parallel beam 28 by performing conventional image processing on the detection image 261; and calculates the position 283 of the front end of the tool 3 by calculating its center position based on the outline 282 of the front end of the tool 3 through edge detection.

[0161] As a result, by performing optical detection by the detection unit 20, the position of the front end of the tool 3 can be detected with high precision in a non-contact manner.

[0162] Furthermore, during position detection, the tool 3 can be positioned simply by placing the front end of the tool 3 into the parallel beam 28 between the illumination unit 24 and the imaging unit (focal stop lens 25 and CCD camera 26), making the detection operation easier.

[0163] In this embodiment, since the detection unit 20 has a fixing mechanism relative to the rotary table 13, the setting position of the detection unit 20 relative to the rotary table 13 can remain unchanged between detection actions at various angular positions.

[0164] [Second Implementation]

[0165] exist Figures 10A to 10C The second embodiment of the present invention is shown in the figure.

[0166] In the first embodiment described above, in order to perform the work machine 1 (refer to...) Figure 1 The measurement of the C-axis center position is performed by setting up a detection unit 20 on the rotary table 13 (refer to...). Figure 2 and Figure 3 The first straight line L1 is detected by the radial position detection action of tool 3 at angular positions A0 and A180, and the second straight line L2 is detected by the same detection action at angular positions A90 and A270. The intersection point Pc is measured as the correct C-axis center position of the working machine 1.

[0167] In contrast, in this embodiment, the correct C-axis center position of the machine tool 1 is measured by detecting the circumferential position, i.e., the planar position along the surface of the rotary table 13, together with the radial position of the tool 3 during the detection action at angular positions A0 and A180.

[0168] exist Figure 10A In the middle, a detection unit 20A is placed on the rotary table 13 at the angular position A0.

[0169] The detection unit 20A has the same basic structure as the detection unit 20 in the first embodiment, and therefore, it can perform coordinate detection in the depth direction of the image using the autofocus function. For example, in coordinate detection using the autofocus function... Figure 5 In the detected image 261, edge detection is performed on the outline 282 of the shadow 281 of tool 3. By detecting the focal position with the maximum contrast, the coordinates of the depth direction of the image can be correctly detected.

[0170] Therefore, by introducing tool 3 into the detection unit 20A placed on the rotary table 13, the radial position Rc and circumferential position Cc of tool 3 relative to the rotary table 13 can be detected. Through such a detection action at the angular position A0, the planar position PA0 of tool 3 relative to the rotary table 13 is measured.

[0171] exist Figure 10B Once the detection action at angle position A0 is completed, the rotary table 13 is moved to angle position A180. By performing the same detection action at angle position A180, the plane position of the measuring tool 3 relative to the rotary table 13 is PA180.

[0172] exist Figure 10C Once the planar positions PA0 and PA180 are obtained, the calculation unit 27 calculates the midpoint PAc of the line segment LA connecting the planar positions PA0 and PA180. The correct C-axis center position of the machine tool 1 can be measured through this midpoint PAc.

[0173] This embodiment achieves the same effect as the first embodiment described above, and the detection action at the front end of the tool 3 is sufficient at angle positions A0 and A180, which improves work efficiency.

[0174] Furthermore, in this embodiment, since there is no need for detection actions at other angular positions such as angular positions A90 and A270 as in the first embodiment, even if the working machine 1 is outside the scope of detection actions at angular positions A90 and A270 due to the structural constraints of the translation axis (XYZ axis), the correct C-axis center position can be measured by detection actions at angular positions A0 and A180.

[0175] [Third Implementation]

[0176] exist Figures 11A to 12C The third embodiment of the present invention is shown in the figure.

[0177] In the first embodiment described above, detection actions are performed at angle positions A0, A180 and angle positions A90, A270. In the second embodiment, detection actions are performed at angle positions A0 and A180, respectively, requiring detection actions at angle positions A0 and A180 that are opposite to the center of the rotating worktable 13.

[0178] In contrast, in this embodiment, the detection of the front end position of the tool 3 is performed at multiple angle positions An from angle position A0 to less than 180 degrees, in the same manner as in the first embodiment, and the correct C-axis center position of the working machine 1 is calculated by calculating the detection results.

[0179] In this embodiment, the working machine 1, the rotary table 13, and the detection unit 20 are the same as in the first embodiment described above, and repeated descriptions of these structures are omitted.

[0180] exist Figure 11A First, the rotary table 13 equipped with the detection unit 20 is positioned at angular position A0. The front end of the tool 3 is then inserted into the opening 23 of the detection unit 20, and the detection unit 20 detects this position as the position P0 of the tool 3.

[0181] exist Figure 11B Then, the rotary table 13 is rotated 30 degrees to the next angular position A30, and the position P30 of tool 3 is detected by the same operation as at angular position A0.

[0182] exist Figure 11C Then, rotate the rotary table 13 by 30 degrees to the next angular position A60, and use the same operation as at angular position A0 to detect the position P60 of tool 3.

[0183] exist Figure 12A In the middle, the rotary table 13 is rotated to the next angular position A120, and the position P120 of the tool 3 is detected by the same operation as at angular position A0.

[0184] exist Figure 12B In the middle, the rotary table 13 is rotated to the next angular position A150, and the position P150 of the tool 3 is detected by the same operation as at angular position A0.

[0185] exist Figure 12C In the above-mentioned angle positions A0 to A150, the positions P0 to P150 of tool 3 are arranged in an arc shape when plotted on the screen. For the point array arranged in an arc shape at positions P0 to P150, the position of the center point PBc of the arc shape can be calculated with high precision, for example, by using the least squares method. The center point PBc obtained here can be measured as the correct C-axis center position of the working machine 1.

[0186] This embodiment achieves the same effect as the first embodiment described above. Even if the range of the detection action is less than 180 degrees due to the structural limitations of the translation axis (XYZ axis) of the machine tool 1, the correct C-axis center position can be measured by the detection action at multiple positions.

[0187] [Variations on embodiments 1 to 3]

[0188] In the first to third embodiments described above, during the detection operation at the angular position An, the detection unit 20 takes an image of the front end of the tool 3, but the position on the detection image of the tool 3 can also be shifted according to the angular position An.

[0189] exist Figure 13 In the detection image 261 of the detection unit 20, the position of the outline 282 of the shadow 281 of the tool 3 on the detection image 261 is not always the same at angular position A0 and other angular positions An. However, as long as the displacement dc0 from the position of angular position A0 (double-dotted line) can be calculated through image processing of the detection image 261, the coordinates of the tool 3 can be determined through corresponding corrections, and the position of the tool 3 on the detection image 261 can also be shifted according to the angular position An.

[0190] [Fourth Implementation]

[0191] exist Figures 14 to 16 The fourth embodiment of the present invention is shown in the figure.

[0192] In this embodiment, the offset distance (offset) from the center position of the A-axis of the machine tool 1 to the front end of the tool 3 is measured.

[0193] The working machine 1 and the detection unit 20 used in the measurement in this embodiment are the same as those in the first embodiment described above, so repeated descriptions are omitted.

[0194] In this embodiment, a detection unit 20 is provided on the rotary table 13.

[0195] The detection unit 20 is configured such that the opening 23 is located at the center of the rotary table 13 (the center of rotation of the C-axis). Furthermore, the orientation of the detection unit 20 is adjusted so that the orientation of the parallel beam 28 aligns with the X-axis direction of the machine tool 1. The orientation of the detection unit 20 can also be adjusted by rotating the rotary table 13 along its C-axis.

[0196] After the detection unit 20 is set up, the spindle head 17 is brought closer to the detection unit 20 by the movement of each axis of the working machine 1, and the front end of the tool 3 mounted on the spindle 18 is guided into the opening 23 to perform the detection action.

[0197] exist Figure 15AFirst, by rotating the A-axis of the working machine 1, the tool 3 is positioned facing the Y-axis "+" direction (angle position A0 around the A-axis). In this state, the front end of the tool 3 is guided into the opening 23 by moving the axes of the working machine 1. Then, adjustments are made by moving the Y-axis and Z-axis of the working machine 1 so that the front end position 283 of the shadow 281 of the tool 3 in the detection image 262 obtained by the detection unit 20 is brought to the center of the detection image 262. The Y-axis and Z-axis positions of the working machine 1 at this time (…) Figure 16 Y1 and Z1 records.

[0198] exist Figure 15B Next, the A-axis of the working machine 1 is rotated, and the tool 3 is positioned facing the Y-axis "-" direction (angle position A180 opposite angle position A0 across the A-axis). In this state, the front end of the tool 3 is guided into the opening 23 by moving the axes of the working machine 1. Furthermore, the Y-axis and Z-axis of the working machine 1 are adjusted so that the front end position 283 of the shadow 281 of the tool 3 is in the center of the detection image 262 obtained by the detection unit 20. The Y-axis position and Z-axis position of the working machine 1 at this time are adjusted. Figure 16 The Y2 and Z2 records.

[0199] exist Figure 16 In the middle, the difference between the Y-axis position Y1 and Z-axis position Z1 of the working machine 1 at angle position A0 and the Y-axis position Y2 and Z-axis position Z2 of the working machine 1 at angle position A180 is the oscillation of the rotation center on the A-axis (rotation axis 171 of the spindle head 17) based on the result of configuring the front end of the tool 3 to the same position respectively.

[0200] Therefore, based on half the difference between the positions of each axis at angular positions A0 and A180, the offset distance (offset) from the center position of axis A of machine tool 1 to the front end of tool 3 can be measured (Y = (Y1 - Y2) / 2, Z = (Z1 - Z2) / 2).

[0201] With this embodiment, the same effect as the first embodiment described above can be obtained in measuring the offset distance (offset) from the center position of the A-axis to the front end of the tool 3.

[0202] [Fifth Implementation]

[0203] exist Figures 17 to 20 The fifth embodiment of the present invention is shown in the figure.

[0204] In this embodiment, the coordinates of the center position of the A-axis of the so-called cradle-type working machine 1A are measured to coincide with the front end of the tool 3.

[0205] exist Figure 17 In the middle, the rotary table 13 is moved by the cradle 131 to move the table 12 (see reference). Figure 1 The support allows the cradle 131 to rotate about the C-axis relative to the cradle 131. The cradle 131 is rotatable about the A-axis relative to the movable worktable 12 via a pair of pivots 132.

[0206] Additionally, in machine tool 1A, the spindle head 17 is positioned relative to the slide 16 (see reference). Figure 1 It is fixed and does not rotate along the A-axis; it is always kept facing downwards along the Z-axis.

[0207] In this embodiment, a detection unit 20 is provided on the rotary table 13. The detection unit 20 is the same as in the first embodiment described above, so repeated descriptions are omitted.

[0208] The detection unit 20 is configured such that the opening 23 is located at the center of the rotary table 13 (the center of rotation of the C-axis). Furthermore, the orientation of the detection unit 20 is adjusted so that the orientation of the parallel beam 28 aligns with the X-axis direction of the machine tool 1A. The orientation of the detection unit 20 is adjusted by rotating the rotary table 13 along its C-axis.

[0209] After the detection unit 20 is set up, the spindle head 17 is brought closer to the detection unit 20 by the movement of each axis of the working machine 1A, and the front end of the tool 3 mounted on the spindle 18 is guided into the opening 23 to perform the detection action.

[0210] exist Figure 18 In (A), the cradle 131 is first rotated along the A-axis to set the rotary table 13 to face the Y-axis "+" direction (angle position A0 around the A-axis). In this state, the front end of the tool 3 is guided into the opening 23 by moving the axes of the working machine 1A.

[0211] exist Figure 19A In the process, with the cradle 131 set to angle position A0, adjustments are made by moving the Y-axis and Z-axis of the working machine 1A so that in the detection image 263 obtained by the detection unit 20, the front end position 283 of the shadow 281 of the tool 3 comes to the center of the detection image 263. The Y-axis and Z-axis positions of the working machine 1A at this time are... Figure 20 Y1 and Z1 records.

[0212] exist Figure 18 In (B), the cradle 131 is rotated along its A-axis to a state where the rotary table 13 faces the Y-axis "-" direction (angle position A180 opposite angle position A0 across the A-axis). In this state, the front end of the tool 3 is guided into the opening 23 by moving each axis of the machine tool 1A.

[0213] exist Figure 19B In the process, with the cradle 131 set to angle position A180, adjustments are made by moving the Y-axis and Z-axis of the working machine 1A so that in the detection image 263 obtained by the detection unit 20, the front end position 283 of the shadow 281 of the tool 3 comes to the center of the detection image 263. The Y-axis and Z-axis positions of the working machine 1A at this time are... Figure 20 The Y2 and Z2 records.

[0214] exist Figure 20 In the middle, the difference between the Y-axis position Y1 and Z-axis position Z1 of the working machine 1A at angle position A0 and the Y-axis position Y2 and Z-axis position Z2 of the working machine 1A at angle position A180 is based on the result of configuring the front end of the tool 3 to the same position, and the swing of the A-axis rotation center of the cradle 131.

[0215] Therefore, based on the positions of each axis at angular positions A0 and A180, the coordinates of the center position of the A-axis of the working machine 1A and the front end of the tool 3 can be measured by using the formula (Y=(Y1+Y2) / 2,Z=(Z1+Z2) / 2).

[0216] With this embodiment, when measuring the coordinates where the center position of the A-axis coincides with the front end of the tool 3, the same effect as the first embodiment described above can be obtained.

[0217] [Sixth Implementation]

[0218] exist Figures 21A to 23C The sixth embodiment of the present invention is shown in the figure.

[0219] This embodiment uses the same structure as the fourth embodiment described above, and measures the offset distance (offset) from the center position of the A-axis of the machine tool 1 to the front end of the tool 3.

[0220] However, compared to the fourth embodiment where the Y-axis positions Y1, Y2 and Z-axis positions Z1, Z2 of the detection machine 1 are located at two locations: angular position A0 and angular position A180, which is opposite to angular position A0 (i.e., 180 degrees apart) on the A-axis, in this embodiment, the detection of Y-axis and Z-axis positions is performed at multiple angular positions An within the range from angular position A0 to 180 degrees.

[0221] exist Figure 21A First, by rotating the A-axis of the working machine 1 (rotating the rotation axis 171 of the spindle head 17), the tool 3 is positioned in the Y-axis "+" direction (angle position A0 around the A-axis). In this state, the front end of the tool 3 is guided into the opening 23 by moving each axis of the working machine 1.

[0222] exist Figure 21BIn the process, after tool 3 is positioned at angular position A0, it is adjusted by moving the Y-axis and Z-axis of the working machine 1 so that the front end position 283 of the shadow 281 of tool 3 is in the center of the detection image 264 obtained by the detection unit 20. The Y-axis and Z-axis positions of the working machine 1 at this time are recorded. The recorded Y-axis and Z-axis positions are the A-axis center positions Q0 at each angular position An.

[0223] Next, by rotating the A-axis of the working machine 1, the tool 3 is set to the angular position A30 (rotated 30 degrees from the angular position A0). In this state, similar to the angular position A0, the front end of the tool 3 is guided into the opening 23 by moving each axis of the working machine 1. Adjustments are made so that the front end position 283 of the shadow 281 of the tool 3 in the detection image 264 obtained by the detection unit 20 comes to the center of the detection image 264. The Y-axis position and Z-axis position (A-axis center position Q30) of the working machine 1 at this time are recorded.

[0224] Then, by rotating the A-axis of the machine tool 1, the tool 3 is set to the angular position A60 (rotated 60 degrees from the angular position A0). The Y-axis position and Z-axis position (A-axis center position Q60) of the machine tool 1 are recorded in the same order as the angular positions A0 and A30.

[0225] Similarly, record the Y-axis and Z-axis positions (A-axis center positions Q90, Q120, Q150, Q180) of the working machine 1 at angle positions A90, A120, A150, and A180.

[0226] exist Figure 21C If the A-axis center positions Qn (Q0-Q180) at the angular positions An (A0-A180) obtained by repeatedly performing the above detection actions are plotted on the screen, they become a point sequence QC arranged in an arc shape. For these point sequences QC, the position of the center point QCc (the common front end position of the tool 3 for all angular positions An) of the arc-shaped point sequence QC can be calculated with high precision, for example, by using the least squares method. Using the center point QCc obtained here, the displacement distance (offset) from the A-axis center position Qn of the machine tool 1 to the front end of the tool 3 can be accurately measured.

[0227] This embodiment achieves the same effects as the first and fourth embodiments described above. Even if the range of detection actions that can be performed is less than 180 degrees due to the structural limitations of the translation axis (XYZ axis) of the machine tool 1, the distance (offset) of the misalignment from the center position Qn of the A axis to the front end of the tool 3 can be accurately measured by the detection actions at multiple angular positions An.

[0228] [Modifications of the 6th Embodiment]

[0229] exist Figure 22 In the above-described sixth embodiment, the distance (offset) of the misalignment from the center position Qn of the A-axis to the front end of the tool 3 is measured and recorded in the NC device of the machine tool 1 as a reference for the correction value when the machine tool 1 is in motion.

[0230] When registering with the NC device of machine tool 1, the distance D (offset) from the center point QCc, which is the front end position of tool 3, to the actual center position Qn of the A-axis is required. By performing a least-squares operation on the arc-shaped point sequence QC based on the center position Qn of the A-axis, together with the position of the center point QCc, an approximate arc radius representing the distance D (approximate value) from the center point QCc to the center position Qn of the A-axis can be obtained. Therefore, this radius can be set as the actual distance D between the center point QCc and the center position Qn of the A-axis.

[0231] When registering with the NC device of machine tool 1, the distance D must be separated into a component Dz in the Z-axis direction parallel to tool 3 and a component Dy in the Y-axis direction orthogonal to tool 3. Therefore, the angle θ of the line segment connecting the center position Qn of the A-axis to the front end (center point QCc) of tool 3 is required. However, the angle θ of the line segment giving an approximate radius of the arc (distance D) cannot be obtained using the least squares method used in the calculation of center point QCc.

[0232] exist Figure 23A In addition to not being able to obtain the aforementioned angle θ, the A-axis center position Qn (sampling point) detected by the arc-shaped point sequence QC at the aforementioned multiple angular positions An (A0~A180) deviates (radial displacement) from the approximate arc of the point sequence QC. Furthermore, if a reference line Ln extending from the center point QCc is drawn with the angular position An (0 degrees~180 degrees) set as the angular position for detecting the A-axis center position Qn, then the A-axis center position Qn at each angle deviates (circumferential displacement) from these reference lines Ln.

[0233] Under such an error distribution, the following operation can be used to determine the optimal value of the angle θ.

[0234] exist Figure 23B In the first operation, tool 3 is used to locate the center position Q90 of the A-axis along the Z-axis (angle position A90). Specifically, the line segment extending from the center point QCc to the center position Q90 of the A-axis is calculated, and the angle between this line segment and the Z-axis is set as θ.

[0235] Although this operation is not optimal overall, it is the most suitable benchmark.

[0236] exist Figure 23C In the second operation, the line segment extending from the center point QCc to the center position Q130 of the A-axis can also be determined with the tool 3 facing at a specified angle (e.g., 40 degrees) relative to the Z-axis (angle position A130, which is 130 degrees away from angle position A0). The angle between this line segment and the reference line L130, which is 40 degrees from the Z-axis, is set as θ.

[0237] Furthermore, the angle θn with the baseline Ln can be calculated at the center position Qn of the A-axis, which is located at multiple angular positions An, and its average value can be obtained.

[0238] Although this operation is relatively complicated, it can yield the overall optimal angle θ.

[0239] In the above-mentioned center position Qn of the A-axis at multiple angular positions An, the entire range can be equally divided to obtain the angle θ, but the sampling density of a portion of the angular range can also be increased or decreased.

[0240] After obtaining angle θ through the above operations, the Z-axis component Dz and the Y-axis component Dy, which is orthogonal to tool 3 (refer to...) Figure 22 The values ​​can be calculated using Dz = Dcosθ and Dy = Dsinθ, respectively.

[0241] [Variations of Embodiments 1 to 6]

[0242] In the first to sixth embodiments described above, the detection unit 20 and the front end of the detection tool 3 are respectively located at the front end of the detection tool 3.

[0243] For example, in the first embodiment, such as Figure 5 As shown, the front end of tool 3 is positioned at the center of the detection image 261 of CCD camera 26. Based on the outline 282 of the shadow 281 of the front end of tool 3 presented in the detection image 261, the coordinates (Tv, Th) of the front end position 283 of tool 3 are calculated.

[0244] At this time, the front end of tool 3 has a complex concave-convex shape, and the coordinates cannot be detected correctly based on the shape of the front end of tool 3.

[0245] In order to easily and accurately detect the front end position (Tv, Th) of tool 3, the following sequence can be used.

[0246] [Seventh Implementation]

[0247] like Figure 24A As shown, in the CCD camera 26 (reference) Figure 3 In the detection image 261, the shadow 281 of the tip of tool 3 is visible (and...). Figure 5 Similarly). The front end position 283 of tool 3 is presented in a portion of the outline 282 of shadow 281, requiring the measurement of the coordinates (Tv, Th).

[0248] In this embodiment, while the tool 3 is rotated relative to the CCD camera 26, the CCD camera 26 detects a detection image 265 (same as the detection images 261 to 264 in the first to sixth embodiments), and the outline 282 of the tool 3 is detected based on the detection image 265.

[0249] In this embodiment, by rotating the tool 3, the contour 282 presented in the detection image 265 is symmetrical with respect to the rotation center. Based on the symmetry of the contour 282, the central axis 284 of the tool 3 can be correctly detected, and the intersection of the central axis 284 and the contour 282 is detected as the front end position 283 of the tool 3.

[0250] In this embodiment, when the contour 282 detection tool 3 is used to detect the center axis 284, the following calculation process is performed.

[0251] like Figure 24B As shown, in the detection image 265, tool 3 is configured to a specified angular position (e.g., Figure 21B The angle position shown (A90) is set as the extension direction D90 of tool 3 at this time. Next, a plurality of cross-sections 30, which are orthogonal to the extension direction D90 and cross-sections of the contour 282, are set parallel to the extension direction D90 at a predetermined interval.

[0252] like Figure 24C As shown, for the multiple cross-sections 30 set, the two intersection points 31 and 32 with the contour 282 are detected respectively, and then the midpoint 33 of the two intersection points 31 and 32 is detected. Furthermore, by detecting the straight line passing through the midpoint 33 of each cross-section 30, the straight line can be set as the central axis 284 of the tool 3.

[0253] In this embodiment, by utilizing the extension direction Dn of tool 3 (each angular position An, orientation of tool 3, approximate axial direction) to detect the axis of rotational symmetry, the correct central axis 284 of tool 3 can be detected, and the coordinates (Th, Tv) of the front end position 283 of tool 3 can be detected with high precision based on the intersection of the correct central axis 284 and the contour 282.

[0254] At this time, by detecting the midpoints of multiple cross-sections 30 in the detection of the central axis 284, and by detecting the intersection with the contour 282 in the detection of the front end position 283, geometric calculations can be performed respectively, thereby enabling high-precision and simple measurement of the front end position 283 of the tool 3 and the center position of the rotation axis (A-axis or C-axis).

[0255] In this embodiment, the orientation (extension direction Dn) of tool 3 can be set to any angle (angle position An).

[0256] exist Figure 25A In the middle, set tool 3 to angle position A150, and set multiple transverse lines 30 that are orthogonal to the extension direction D150.

[0257] like Figure 25B As shown, by detecting two intersection points 31, 32 and midpoint 33 in each cross section 30, the coordinates (Th, Tv) of the front end position 283 of the tool 3 can be correctly detected based on the intersection of the central axis 284 passing through multiple midpoints 33 and the contour 282.

[0258] [Eighth Implementation]

[0259] In the seventh embodiment described above, the midpoint detection of multiple cross-sections 30 is performed when the central axis 284 of the contour 282 detection tool 3 is used.

[0260] In contrast, in this embodiment, the central axis 284 of the tool 3 is detected by pattern recognition on each side of the contour 282, which is a rotationally symmetric graphic.

[0261] exist Figure 26A As shown, in the detection image 265, tool 3 is positioned at a specified angular location (e.g., Figure 21B The angle position A90 shown is set as the extension direction D90 of tool 3 at this time. Next, the shape 41 of one side of the contour 282 (a part that divides the contour 282 into two parts by a straight line along the extension direction D90) is detected relative to the extension direction D90 as a reference pattern 40.

[0262] like Figure 26B As shown, after the reference pattern 40 can be detected, a symmetrical pattern 42 that is consistent with the shape of the inverted reference pattern 40 is calculated, and a shape 43 that is consistent with the symmetrical pattern 42 is detected according to the contour 282. After the symmetrical pattern 42 can be detected, the straight line passing through the middle of the reference pattern 40 and the symmetrical pattern 42 (the axis of line symmetry between the reference pattern 40 and the symmetrical pattern 42) is set as the central axis 284 of the tool 3.

[0263] In this embodiment, by utilizing the extension direction Dn of the tool 3 (each angular position An, the orientation of the tool 3, and the approximate axial direction), and through pattern recognition on each side of the contour 282, the correct central axis 284 of the tool 3 can be detected. Based on the intersection of the correct central axis 284 and the contour 282, the coordinates (Th, Tv) of the front end position 283 of the tool 3 can be detected with high precision.

[0264] At this time, as pattern recognition on each side of the contour 282, the detection of the reference pattern 40 and the symmetrical pattern 42 can be performed through geometric operations, thereby enabling high-precision and simple measurement of the front end position 283 of the tool 3 and the center position of the rotation axis (A-axis or C-axis).

[0265] [Ninth Implementation]

[0266] In the seventh embodiment described above, after the central axis 284 of the tool 3 is detected based on the contour 282, the intersection of the central axis 284 and the contour 282 is detected as the front end position 283 of the tool 3.

[0267] In contrast, in this embodiment, by setting an auxiliary contour line on the contour 282 of the front end of the tool 3, the front end position of the tool 3 can be determined even for tools 3 with multiple protrusions on the front end or tools 3 with a front end offset from the center, where the shape of the contour 282 of the front end is unclear in the rotating state.

[0268] like Figure 27A and Figure 27B As shown, assume that a pair of cutting heads 3T, facing each other across the center of rotation, are formed at the front end of tool 3. Figure 27B In the middle, the cutter head 3T, represented by the solid line, moves to the position represented by the double-dotted line by rotating the tool 3.

[0269] In each of the above embodiments, the front end of the tool 3 is photographed from the side of the tool 3 (in the direction intersecting the rotation axis of the tool 3) using a CCD camera 26.

[0270] For example, let's say a CCD camera 26 from Figure 27B The lower part of the image shows tool 3 being photographed, with a pair of blades 3T facing each other in a direction orthogonal to the optical axis of the CCD camera 26 (in...). Figure 27B In the state of the solid line, both cutter heads 3T can be included within the focusing range Rf0 of the CCD camera 26. However, as the tool 3 rotates, the pair of cutter heads 3T approach a state along the optical axis of the CCD camera 26 (in the solid line state). Figure 27B (The middle is the state of double dotted lines), the difference in distance from the CCD camera 26 to each cutter head 3T is widened, so that one is in the focal depth range Rf1 which is farther from the CCD camera 26 and the other is in the focal depth range Rf2 which is closer to the CCD camera 26, and the CCD camera 26 cannot focus on both of the pair of cutter heads 3T.

[0271] In this way, by rotating the tool 3, the distance between the pair of blades 3T and the CCD camera 26 changes periodically, resulting in blurring in a portion of the image captured by the CCD camera 26.

[0272] like Figure 27C As shown, the outline 282 of the shadow 281 of tool 3 is clear except for the front end, but the front end is blurred because the pair of blades 3T are displaced in the optical axis direction of the CCD camera 26. As a result, the coordinates of the front end position 283 of tool 3 cannot be determined by the intersection of the central axis 284 and the outline 282 as in the 7th and 8th embodiments described above.

[0273] In contrast, in this embodiment, the central axis 284 is detected in the same manner as in the 7th or 8th embodiment described above, and an auxiliary contour line is set for the contour 282 of the front end of the tool 3. The intersection of the auxiliary contour line and the central axis 284 is detected as the front end position 283 of the tool 3. Specifically, the following order is adopted.

[0274] exist Figure 28A In the process, after detecting the central axis 284 for the shadow 281 of tool 3, a pair of parallel lines Ma and Mb, parallel to the central axis 284, are set on both sides of the central axis 284 at a predetermined distance Ofs. Here, the predetermined distance Ofs is set so that the intersection points Ca and Cb of the pair of parallel lines Ma and Mb with the contour 282 pass through the non-blurred portion of the contour 282. The predetermined distance Ofs can also be adjusted by observing the state of the contour 282, or it can be set based on the design dimensions of the tool head 3T of tool 3.

[0275] exist Figure 28B In the process, after obtaining the intersection points Ca and Cb of a pair of parallel lines Ma and Mb with the contour 282, an auxiliary contour 285 is set that passes through a pair of intersection points Ca and Cb and is orthogonal to the central axis 284. The intersection point of the central axis 284 and the auxiliary contour 285 is detected as the front end position 283 of the tool 3.

[0276] In this embodiment, by setting an auxiliary contour 285, even for tools 3 with multiple protrusions at the front end, such as a pair of cutting heads 3T, or tools 3 with an offset front end, where the shape of the front end contour 282 becomes unclear in a rotating state, the front end position 283 of the tool 3 can be determined by the intersection of the central axis 284 and the auxiliary contour 285. Therefore, for tools 3 with various front end shapes, the front end position 283 and the center position of the rotation axis (A-axis or C-axis) of the tool 3 can be measured with high precision through simple calculations.

[0277] [Other implementation methods]

[0278] Furthermore, the present invention is not limited to the embodiments described above, and variations and the like that that can achieve the purpose of the present invention are included in the present invention.

[0279] In the above embodiments, the rotation center position of the C-axis or A-axis of the 5-axis controlled working machine 1, 1A was measured, but the working machine and axis of the present invention can be arbitrarily selected.

[0280] For example, as a machine tool, it can be a 5-axis control system with an A-axis and a B-axis as rotating axes, and the rotation center position of its B-axis can be measured. Furthermore, the machine tool can also be a 4-axis or 6-axis control system, as long as it has a structure that at least has a rotating axis whose rotation center position is a problem.

[0281] In the above embodiment, detection units 20 and 20A are used to detect the position of the front end of the tool 3. However, the detection units 20 and 20A are not limited to forming a parallel beam 28. The structure of the object can also be scanned by oscillating the laser beam in parallel (simulated as a parallel beam). Furthermore, other detection methods can be used as long as it is non-contact with the tool 3.

[0282] Industrial availability

[0283] This invention can be used for measuring the center position of the rotating shaft of a machine tool.

[0284] Label Explanation

[0285] 1. 1A…Working machine; 2…Workpiece; 3…Tool; 3T…Cutting head; 9…Control device; 91…Motion control unit; 92…Tool position detection unit; 11…Bed; 12…Moving worktable; 13…Rotary worktable; 131…Rocking register; 132…Pivot; 14…Column; 15…Saddle; 16…Slide; 17…Spindle head; 171…Rotary axis; 18…Spindle; 20, 20A…Detection unit; 21…Box; 22…Including 23…foot of the fixing mechanism; 24…opening; 25…illumination unit; 26…focal stop lens; 27…CCD camera as the imaging unit; 261-265…image detection; 28…processing unit; 29…parallel beam; 281…shadow; 282…outline; 283…front end position; 284…central axis; 285…auxiliary outline line; 20…object to be detected; 31, 32…intersection point; 33…midpoint; A0-A270, An…angle Position; Ca, Cb…intersection; Cc…circumferential position; D…distance; D1…first direction; D2…second direction; dc0…displacement; Dy…Y-axis component; Dz…Z-axis component; L01, L02…line segment; L1…first straight line; L130…baseline; L2…second straight line; LA…line segment; Ln…baseline; Ma, Mb…parallel lines; Ofs…specified interval; P0~P270…tool tip position Position; PA0, PA180…planar position; PAc…midpoint; PBc…center point; Pc…intersection point; Q0~Q180, Qn…center position of A-axis; QC…point sequence; QCc…center point; Rc…radial position; Th, Tv…coordinates of the front end position; Tx0~Tx270…X-axis coordinates; Ty0~Ty270…Y-axis coordinates; Y1, Y2…Y-axis position; Z1, Z2…Z-axis position; θ, θn…angle.

Claims

1. A method for measuring the center position of a rotating shaft of a machine tool, characterized in that, A tool is mounted on the spindle, and a detection unit capable of non-contactly detecting the radial position of the worktable of the tool is set on the worktable. Regarding the rotation axis of the object being measured, the tool and the worktable are divided into four angular positions: two angular positions opposite each other in the first direction across the rotation axis, and two angular positions opposite each other in the second direction intersecting the first direction across the rotation axis. The radial position of the tool relative to the worktable is detected by repeatedly performing the detection action of using the detection unit to detect the position of the tool relative to the worktable at each angular position. The first straight line, which is detected by multiple detection actions, passes through the midpoint of the line segment connecting the positions of the tool detected at two opposite angle positions in the first direction and intersects the first direction, and the second straight line passes through the midpoint of the line segment connecting the positions of the tool detected at two opposite angle positions in the second direction and intersects the second direction. The intersection of the first straight line and the second straight line is measured as the center position of the rotation axis.

2. The method for measuring the center position of the rotating shaft of a working machine as described in claim 1, characterized in that, The aforementioned detection unit is capable of non-contactly detecting that the tip of the aforementioned tool is located at a specific position within the detection unit; In the above detection operation, the spindle and the worktable are moved relative to each other to divide the tool and the worktable into a predetermined angular position. At each of the angular positions, the relative position of the spindle and the worktable is adjusted so that the tool comes to the specific position of the detection unit. In this state, the position of the tool relative to the worktable at each of the angular positions is detected according to the relative position of the spindle and the worktable.

3. The method for measuring the center position of the rotating shaft of a working machine as described in claim 1, characterized in that, The aforementioned detection unit has a fixing mechanism relative to the aforementioned worktable.

4. The method for measuring the center position of the rotating shaft of a working machine as described in any one of claims 1 to 3, characterized in that, The detection unit described above has an illumination unit for illuminating a parallel beam of light and an imaging unit for detecting the parallel beam of light; Based on the image detected by the aforementioned camera unit, the position of the front end of the aforementioned tool disposed in the aforementioned parallel beam is detected.

5. The method for measuring the center position of the rotating shaft of a working machine as described in claim 4, characterized in that, The image is detected by the camera unit while the tool is rotated relative to the camera unit. The outline of the tool is detected based on the image above, and the central axis of the tool is detected based on the symmetry of the outline above. The intersection of the central axis and the contour is used as the front end position of the tool.

6. The method for measuring the center position of the rotating shaft of a working machine as described in claim 5, characterized in that, When the intersection of the aforementioned central axis and the aforementioned contour is used as the position of the tool's front end, A pair of parallel lines are set at a predetermined distance on both sides of the aforementioned central axis. An auxiliary contour line is set that passes through the intersection of the pair of parallel lines and the aforementioned contour and is orthogonal to the aforementioned central axis. The intersection of the central axis and the auxiliary contour line is used as the front end position of the tool.

7. The method for measuring the center position of the rotating shaft of a working machine as described in claim 5 or 6, characterized in that, Multiple transverse lines are set to intersect the contour in the extension direction of the tool. Two intersection points and the midpoint of the two intersection points with each transverse line are detected. A straight line passing through the midpoint of each transverse line is taken as the central axis of the tool.

8. The method for measuring the center position of the rotating shaft of a working machine as described in claim 5 or 6, characterized in that, The shape of one side of the profile is detected relative to the extension direction of the tool and used as a reference pattern. A symmetrical pattern that is consistent with the shape of the inverted reference pattern is detected based on the profile. The straight line passing through the middle of the reference pattern and the symmetrical pattern is used as the central axis of the tool.

Images