Tool angle detection method and tool angle detection device

Abstract

To provide a technique that can detect an attachment angle of a tool to a main shaft in a short time.SOLUTION: A tool angle detection method includes the steps of: (a) determining a search range; (b) taking images of a tool when a rotation angle is a first angle and a tool when a rotation angle is a second angle;(c) calculating a first diameter and a second diameter using the images taken in step (b); and (d) changing the search range to a range of from a third angle to the second angle when the first diameter is larger than the second diameter, and changing the search range to a range of from the first angle to a fourth angle when the first diameter is smaller than the second diameter. Furthermore, the method repeatedly executes the steps (b) through (d) until a difference between the first diameter and the second diameter is less than a first value, or a difference between the first angle and the second angle is less than a second value, and detects an attachment angle of the tool to a main shaft based on the first angle and the second angle in the last step (b) executed.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a tool angle detection method and a tool angle detection device.

Background Art

[0002] Patent Document 1 discloses a cutting edge inspection method in which the cutting edge is rotated about the cutting edge, and the cutting edge is imaged at an angle at which the captured image becomes brightest for each part of the cutting edge, and the shape of the cutting edge such as the minor cutting edge length and the minor cutting edge angle is measured.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technique of Patent Document 1, the shape of the cutting edge of the tool is measured, but the attachment angle of the tool with respect to the spindle has not been studied. There is a need for a technique capable of detecting the above-described attachment angle in a short time.

Means for Solving the Problems

[0005] The present disclosure can be realized in the following forms.

[0006] (1) According to a first aspect of the present disclosure, there is provided a tool angle detection method for detecting an attachment angle of a tool with respect to a spindle. This tool angle detection method includes: (a) a step of determining a search range, which is a range of the rotation angle of the spindle, based on the number of cutting edges of the tool attached to the spindle; (b) a step of imaging the tool when the rotation angle is a first angle and the tool when the rotation angle is a second angle by an imaging unit in a direction intersecting the axis of the spindle, wherein the first angle is greater than a third angle that is the minimum angle within the search range and less than a fourth angle that is the maximum angle within the search range, and the second angle is greater than the first angle and less than the fourth angle; (c) a step of calculating, using the image captured in step (b), a first diameter that is the diameter of the tool as viewed from the imaging unit when the rotation angle is the first angle and a second diameter that is the diameter of the tool as viewed from the imaging unit when the rotation angle is the second angle; (d) a step of changing the search range to a range of greater than or equal to the third angle and less than or equal to the second angle when the first diameter is greater than the second diameter, and changing the search range to a range of greater than or equal to the first angle and less than or equal to the fourth angle when the first diameter is less than the second diameter. The steps (b) to (d) are repeatedly executed until the difference between the first diameter and the second diameter becomes less than a first value that is a predetermined value, or until the difference between the first angle and the second angle becomes less than a second value that is a predetermined value. Finally, the attachment angle of the tool with respect to the spindle is detected based on the first angle and the second angle in the last executed step (b). According to the tool angle detection method of this aspect, the attachment angle of the tool with respect to the spindle can be detected in a short time. (2) In the tool angle detection method of the above form, in the step (b), the tool when the rotation angle is the third angle and the tool when the rotation angle is the fourth angle are imaged by the imaging unit. In the step (c), using the image captured in the step (b), the third diameter which is the diameter of the tool as seen from the imaging unit when the rotation angle is the third angle and the fourth diameter which is the diameter of the tool as seen from the imaging unit when the rotation angle is the fourth angle are calculated. (e) When the third diameter and the fourth diameter are larger than the first diameter and the third diameter and the fourth diameter are larger than the second diameter, a step of shifting the search range may be further provided. According to the tool angle detection method of this form, in the initially determined search range, when the attachment angle of the tool with respect to the spindle cannot be detected even by repeating the steps (b) to (d), the attachment angle of the tool with respect to the spindle can be detected by shifting the search range. (3) In the tool angle detection method of the above form, in the step (e), the search range may be shifted by an angle that is half of the search range. According to the tool angle detection method of this form, by shifting the search range once, the search range can be changed to a range in which the attachment angle of the tool with respect to the spindle can be detected by repeating the steps (b) to (d). (4) In the tool angle detection method of the above form, (f) after the workpiece is machined using the tool, a step of rotating the tool around the axis of the spindle so that the rotation angle becomes a fifth angle at which the part of the tool that the operator desires to check faces the imaging unit, and (g) a step of imaging the tool when the rotation angle is the fifth angle by the imaging unit may be further provided. According to the tool angle detection method of this form, the state of the tool can be checked after the workpiece is machined using the tool. (5) In the tool angle detection method of the above form, the difference between the third angle and the first angle, the difference between the first angle and the second angle, and the difference between the second angle and the fourth angle may be equal. According to the tool angle detection method of this form, every time steps (b) to (d) are repeated once, the angle of the search range can be reduced to two-thirds. (6) In the tool angle detection method of the above form, the ratio of the difference between the third angle and the first angle and the difference between the first angle and the fourth angle may be the golden ratio, and the ratio of the difference between the second angle and the fourth angle and the difference between the third angle and the second angle may also be the golden ratio. According to the tool angle detection method of this form, when the search range is changed to a range greater than or equal to the third angle and less than or equal to the second angle in step (d), the second angle in the search range before the change becomes the fourth angle in the search range after the change, and the first angle in the search range before the change becomes the second angle in the search range after the change. Therefore, for the fourth angle and the second angle in the search range after the change, imaging of the tool and calculation of the diameter have already been performed. Also, when the search range is changed to a range greater than or equal to the first angle and less than or equal to the fourth angle in step (d), the first angle in the search range before the change becomes the third angle in the search range after the change, and the second angle in the search range before the change becomes the first angle in the search range after the change. Therefore, for the third angle and the first angle in the search range after the change, imaging of the tool and calculation of the diameter have already been performed. Therefore, the number of times the imaging unit images the tool and the number of times the calculation unit calculates the diameter of the tool can be reduced. (7) In the tool angle detection method of the above form, the difference between the third angle and the fourth angle is a third value that is a value included in the Fibonacci sequence, the difference between the third angle and the first angle, and the difference between the second angle and the fourth angle are values that are two smaller than the third value among the values included in the Fibonacci sequence, and the difference between the third angle and the second angle may be a value that is one smaller than the third value among the values included in the Fibonacci sequence. According to the tool angle detection method of this form, even if the search range is changed, since the first angle, the second angle, the third angle, and the fourth angle are always integers, when the angular resolution of the spindle is an integer, the mounting angle of the tool with respect to the spindle can be detected in a short time. In the tool angle detection method of the above-described embodiment, even if the steps (b) to (d) are repeated a predetermined number of times, if the difference between the first diameter and the second diameter does not become less than the first value and the difference between the first angle and the second angle does not become less than the second value, the process of detecting the mounting angle may be terminated. According to the tool angle detection method of this embodiment, it is possible to suppress the continuous execution of the tool angle detection process. (9) According to a second aspect of the present disclosure, there is provided a tool angle detection device that detects the attachment angle of a tool with respect to a spindle. This tool angle detection device includes a control unit that rotates the tool attached to the spindle around the axis of the spindle by changing the rotation angle of the spindle, an imaging unit that images the tool attached to the spindle from a direction intersecting the axis of the spindle, and an arithmetic unit. The arithmetic unit determines a search range that is the range of the rotation angle based on the number of cutting edges of the tool. The imaging unit is greater than a third angle that is the minimum angle within the search range and less than a fourth angle that is the maximum angle within the search range, and is a second angle that is greater than the first angle and less than the fourth angle. The imaging unit executes an imaging process of imaging the tool when the rotation angle is the first angle and the tool when the rotation angle is the second angle. The arithmetic unit executes an arithmetic process of calculating a first diameter that is the diameter of the tool as seen from the imaging unit when the rotation angle is the first angle and a second diameter that is the diameter of the tool as seen from the imaging unit when the rotation angle is the second angle using the image captured by the imaging unit. When the first diameter is greater than the second diameter, the arithmetic unit executes a change process of changing the search range to a range of not less than the third angle and not more than the second angle. When the first diameter is less than the second diameter, the arithmetic unit executes a change process of changing the search range to a range of not less than the first angle and not more than the fourth angle. The tool angle detection device repeatedly executes the imaging process, the arithmetic process, and the change process until the difference between the first diameter and the second diameter becomes less than a first value that is a predetermined value, or until the difference between the first angle and the second angle becomes less than a second value that is a predetermined value. The arithmetic unit detects the attachment angle of the tool with respect to the spindle based on the first angle and the second angle in the last executed imaging process. According to the tool angle detection device of this aspect, the attachment angle of the tool with respect to the spindle can be detected in a short time.

Brief Description of the Drawings

[0007]

Figure 1

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Figure 9

Embodiments for Carrying Out the Invention

[0008] A. First Embodiment: FIG. 1 is an explanatory diagram showing the schematic configuration of the tool angle detection device 100. In FIG. 1, arrows representing three coordinate axes X, Y, and Z that are orthogonal to each other are shown. The Z-axis and the X-axis are coordinate axes parallel to the horizontal plane. The Y-axis is a coordinate axis parallel to the vertical direction. When specifying the direction, the positive direction, which is the direction indicated by the arrow, is denoted as "+", and the negative direction, which is the direction opposite to the direction indicated by the arrow, is denoted as "-", and positive and negative signs are used in combination in the direction notation.

[0009] The tool angle detection device 100 is a device that detects the attachment angle of the tool 300 with respect to the spindle 200 provided in a machine tool such as a machining center or a lathe. In the present embodiment, the tool 300 has a blade provided in a rotationally symmetric manner about its axis. The tool 300 is an end mill, a face mill, a drill, or the like. The tool 300 is attached to the spindle 200 such that its axis coincides with the spindle rotation axis AX, which is the axis of the spindle 200. In the present embodiment, the direction along the spindle rotation axis AX is the vertical direction. The attachment angle of the tool 300 with respect to the spindle 200 means the relative angle around the spindle rotation axis AX between the spindle 200 and the tool 300 attached to the spindle 200. The spindle 200 and the tool 300 rotate around the spindle rotation axis AX by the rotational driving force of the servo motor 210. The tool angle detection device 100 includes an imaging unit 10, a control unit 20, and an arithmetic unit (to be described later).

[0010] The imaging unit 10 images the tool 300 attached to the spindle 200 from a direction intersecting the axis of the spindle 200. The imaging unit 10 includes a camera 11 and a backlight 12. In the present embodiment, the camera 11 is fixed on the +X direction side of the tool 300 attached to the spindle 200. The backlight 12 is provided on the side opposite to the camera 11 with respect to the spindle rotation axis AX. The imaging unit 10 images the cutting edge of the tool 300. Note that the imaging unit 10 may image the entire tool 300. The camera 11 is not limited to the +X direction side of the tool 300 attached to the spindle 200, and may be fixed at a position where it can image the tool 300 attached to the spindle 200 from a direction intersecting the spindle rotation axis AX.

[0011] The control unit 20 rotates the tool 300 attached to the spindle 200 around the axis of the spindle 200 by changing the rotation angle of the spindle 200. The control unit 20 is, for example, a CNC (Computerized Numerical Control) device. The control unit 20 changes the rotation angle of the spindle 200 by controlling the servo motor 210 via a drive circuit 220.

[0012] FIG. 2 is a block diagram showing a schematic configuration of the arithmetic unit 30. The arithmetic unit 30 is configured as a computer including a CPU 31, a memory 32, an input / output interface 33, and an internal bus 34. The CPU 31, the memory 32, and the input / output interface 33 are connected to be communicable bidirectionally via the internal bus 34. The memory 32 includes a main storage device such as a RAM and an auxiliary storage device such as a hard disk drive. Connected to the input / output interface 33 are an imaging unit 10, a control unit 20, an input device 35 such as a keyboard and a mouse, and a display device 36 such as a liquid crystal display. Note that the input device 35 and the display device 36 may be integrated as a touch panel.

[0013] The CPU 31 includes an arithmetic unit 40. The arithmetic unit 40 is realized by the CPU 31 executing a program stored in the memory 32. Note that the arithmetic unit 40 may be realized by a circuit. The arithmetic unit 40 will be described later.

[0014] FIG. 3 is a process diagram of the tool angle detection process in the first embodiment. A tool angle detection method for detecting the attachment angle of the tool 300 with respect to the spindle 200 is realized by the tool angle detection process.

[0015] In step S10, the arithmetic unit 40 determines a search range, which is a range of the rotation angle of the spindle 200, based on the number of cutting edges of the tool 300 attached to the spindle 200. For example, when the tool 300 is a two-flute ball end mill, the number of its cutting edges is 2. Hereinafter, the number of cutting edges of the tool 300 attached to the spindle 200 will be simply referred to as the number of cutting edges. The arithmetic unit 40 first determines an initial search angle A, which is a value in the range from 0° to 360°. Then, the arithmetic unit 40 calculates an angle B using the following formula (1). Note that the angle A is determined so that the angle B calculated by formula (1) does not exceed 360°. B = A+(360° / number of cutting edges) ···(1) The calculation unit 40 determines the range of the angle greater than or equal to angle A and less than or equal to angle B as the search range. Hereinafter, the smallest angle within the search range is referred to as the third angle, and the largest angle within the search range is referred to as the fourth angle. That is, within the search range determined in step S10, the third angle is A and the fourth angle is B.

[0016] In step S20, the imaging unit 10 images the tool 300 when the rotation angle of the main shaft 200 is the first angle, the tool 300 when the rotation angle of the main shaft 200 is the second angle, the tool 300 when the rotation angle of the main shaft 200 is the third angle, and the tool 300 when the rotation angle of the main shaft 200 is the fourth angle. Here, the first angle is an angle greater than the third angle and less than the fourth angle, and the second angle is an angle greater than the first angle and less than the fourth angle. When the third angle is A and the fourth angle is B, the first angle M1 and the second angle M2 are calculated by the following formulas (2) and (3), respectively. M1 = A+(B - A) / 3 ··· (2) M2 = A+(B - A)×2 / 3 ··· (3) That is, the difference between the third angle and the first angle, the difference between the first angle and the second angle, and the difference between the second angle and the fourth angle are equal.

[0017] FIG. 4 is a diagram showing an example of the relationship between the rotation angle of the main shaft 200 and the diameter of the tool 300 as viewed from the imaging unit 10. In FIG. 4, the horizontal axis represents the rotation angle of the main shaft 200, and the vertical axis represents the diameter of the tool 300 as viewed from the imaging unit 10. In FIG. 4, the third angle is represented by A, the first angle is represented by M1, the second angle is represented by M2, and the fourth angle is represented by B. Also, in FIG. 4, the actual diameter of the tool 300 as viewed from the imaging unit 10 is indicated by a dashed line.

[0018] In step S20 of FIG. 3, first, the control unit 20 rotates the main shaft 200 so that the rotation angle becomes the first angle by outputting a drive command to the drive circuit 220. Then, with the backlight 12 lit, the imaging unit 10 images the tool 300 when the rotation angle is the first angle. Similarly, the tool 300 when the rotation angle is the second angle, the tool 300 when the rotation angle is the third angle, and the tool 300 when the rotation angle is the fourth angle are imaged. Note that the imaging order is not particularly limited.

[0019] FIG. 5 is a diagram showing an example of an image of the tool 300 imaged by the imaging unit 10. In FIG. 5, the cutting edge of the tool 300 which is a ball end mill is shown. Since the backlight 12 is lit during imaging, the tool 300 is imaged as an image darker than the background. In FIG. 5, the tool 300 is hatched with oblique lines to show that the part of the tool 300 is imaged darkly.

[0020] In step S30 of FIG. 3, the calculation unit 40 calculates a first diameter, a second diameter, a third diameter, and a fourth diameter, which are the diameters of the tool 300, using the images captured in step S20. Here, the first diameter is the diameter of the tool 300 as seen from the imaging unit 10 when the rotation angle is the first angle, the second diameter is the diameter of the tool 300 as seen from the imaging unit 10 when the rotation angle is the second angle, the third diameter is the diameter of the tool 300 as seen from the imaging unit 10 when the rotation angle is the third angle, and the fourth diameter is the diameter of the tool 300 as seen from the imaging unit 10 when the rotation angle is the fourth angle. In FIG. 4, the first diameter is represented as F(M1), the second diameter is represented as F(M2), the third diameter is represented as F(A), and the fourth diameter is represented as F(B). The calculation unit 40 calculates the first diameter, the second diameter, the third diameter, and the fourth diameter by performing image processing on the images captured by the imaging unit 10. The first diameter, the second diameter, the third diameter, and the fourth diameter are the diameters of the tool 300 at the same vertical height position. In FIG. 5, an example of the diameter of the tool 300 calculated by the calculation unit 40 is indicated by an arrow.

[0021] In step S40 of FIG. 3, the arithmetic unit 40 determines whether the third diameter and the fourth diameter are larger than the first diameter and whether the third diameter and the fourth diameter are larger than the second diameter. If the third diameter and the fourth diameter are larger than the first diameter and the third diameter and the fourth diameter are larger than the second diameter, step S50 is executed. If at least one of the third diameter and the fourth diameter is smaller than the first diameter, or if at least one of the third diameter and the fourth diameter is smaller than the second diameter, step S80 is executed.

[0022] In step S50, the arithmetic unit 40 shifts the search range determined in step S10 based on the number of cutting edges of the tool 300. The arithmetic unit 40 shifts the search range from the range of angle A or more and angle B or less to the range of angle A2 or more and angle B2 or less. Angle A2 and angle B2 are calculated by the following formulas (4) and (5), respectively. A2 = A + C / 2 ··· (4) B2 = A2 + C ··· (5) Here, C = 360° / number of cutting edges, and C is equal to the angle of the search range. That is, the arithmetic unit 40 shifts the search range by an angle equal to half of the search range. In the search range after being shifted in step S50, the third angle is A2 and the fourth angle is B2. When the angle B2 calculated by formula (5) exceeds 360°, the arithmetic unit 40 sets the angle A2 as the angle obtained by subtracting 360° from the angle calculated by formula (4), and sets the angle B2 as the angle obtained by subtracting 360° from the angle calculated by formula (5).

[0023] FIG. 6 is a diagram showing an example of the search range. In FIG. 6, the horizontal axis indicates the rotation angle of the main shaft 200, and the vertical axis indicates the diameter of the tool 300 as viewed from the imaging unit 10. The "search range before shift" shown in FIG. 6 is the search range determined in step S10, and the "search range after shift" is the search range after being shifted in step S50. Also, in FIG. 6, the actual diameter of the tool 300 as viewed from the imaging unit 10 is indicated by a dashed line.

[0024] In step S60 of FIG. 3, the imaging unit 10 images the tool 300 when the rotation angle of the main shaft 200 is the first angle, the tool 300 when the rotation angle of the main shaft 200 is the second angle, the tool 300 when the rotation angle of the main shaft 200 is the third angle, and the tool 300 when the rotation angle of the main shaft 200 is the fourth angle. When step S60 is executed for the first time, the third angle is A2, the fourth angle is B2, the first angle is the value obtained by substituting A2 for A and B2 for B in formula (2), and the second angle is the value obtained by substituting A2 for A and B2 for B in formula (3). When step S60 is executed two or more times, the third angle is the minimum angle within the search range changed in the last executed step S90, and the fourth angle is the maximum angle within the search range changed in the last executed step S90. The first angle is the value obtained by substituting the aforementioned third angle for A and the aforementioned fourth angle for B in formula (2), and the second angle is the value obtained by substituting the aforementioned third angle for A and the aforementioned fourth angle for B in formula (3). The imaging of the tool 300 in step S60 is executed in the same procedure as step S20. Step S60 is also called the imaging process.

[0025] In step S70, the calculation unit 40 calculates a first diameter, a second diameter, a third diameter, and a fourth diameter using the image captured in step S60. The calculation of the first diameter, the second diameter, the third diameter, and the fourth diameter is executed in the same manner as step S30. Step S70 is also called the calculation process.

[0026] In step S80, the calculation unit 40 determines whether the difference between the first diameter and the second diameter calculated in step S70 is less than a first value which is a predetermined value. The difference between the first diameter and the second diameter is represented by ΔF in FIG. 4. The first value is preferably a value close to 0. The first value is, for example, 1 μm or 10 μm. When the difference between the first diameter and the second diameter is greater than or equal to the first value, step S90 is executed. When the difference between the first diameter and the second diameter is less than the first value, step S110 is executed.

[0027] In step S90, the calculation unit 40 changes the search range. Step S90 is also called the change process.

[0028] When the first diameter is larger than the second diameter as in the example shown in FIG. 4, in step S90, the arithmetic unit 40 changes the search range from the range of the third angle or more and the fourth angle or less to the range of the third angle or more and the second angle or less. That is, the second angle in the search range before the change becomes the fourth angle in the search range after the change. The third angle does not change before and after the change of the search range.

[0029] FIG. 7 is a diagram showing an example of the relationship between the rotation angle of the main shaft 200 and the diameter of the tool 300 as seen from the imaging unit 10 when the first diameter is smaller than the second diameter. In FIG. 7, the horizontal axis represents the rotation angle of the main shaft 200, and the vertical axis represents the diameter of the tool 300 as seen from the imaging unit 10. In FIG. 7, the third angle is A, the first angle is M1, the second angle is M2, the fourth angle is B, the first diameter is F(M1), the second diameter is F(M2), the third diameter is F(A), and the fourth diameter is F(B). Further, in FIG. 7, the actual diameter of the tool 300 as seen from the imaging unit 10 is indicated by a one-dot chain line.

[0030] When the first diameter is smaller than the second diameter as in the example shown in FIG. 7, in step S90, the arithmetic unit 40 changes the search range from the range of the third angle or more and the fourth angle or less to the range of the first angle or more and the fourth angle or less. That is, the first angle in the search range before the change becomes the third angle in the search range after the change. The fourth angle does not change before and after the change of the search range.

[0031] In step S100 of FIG. 3, the arithmetic unit 40 determines whether steps S60, S70, and S90 have been executed a predetermined number of times. When the above-described three steps have been executed a predetermined number of times, the arithmetic unit 40 ends the tool angle detection process. At this time, the arithmetic unit 40 may cause the display device 36 to display an error. When the above-described three steps have not been executed a predetermined number of times, the arithmetic unit 40 returns the process to step S60. In other words, the arithmetic unit 40 ends the tool angle detection process when the difference between the first diameter and the second diameter does not become less than the first value even if the imaging process, the arithmetic process, and the change process are repeated a predetermined number of times.

[0032] In step S60 executed after the second time, the imaging unit 10 does not image the tool 300 at a rotation angle equal to the rotation angle at which the tool 300 has already been imaged. For example, if in step S90 executed immediately before, the search range is changed from the range of the third angle or more and the fourth angle or less to the range of the third angle or more and the second angle or less, the second angle in the search range before the change is equal to the fourth angle in the search range after the change. Therefore, the imaging unit 10 does not image the tool 300 when the rotation angle of the spindle 200 is the fourth angle in the search range after the change. Also, in step S70 executed after the second time, the calculation unit 40 does not calculate the diameter of the tool 300 at a rotation angle equal to the rotation angle at which the diameter of the tool 300 has already been calculated.

[0033] In step S110, the calculation unit 40 detects the attachment angle of the tool 300 with respect to the spindle 200 based on the first angle and the second angle in the last executed step S60. The calculation unit 40 determines, for example, the average value of the first angle and the second angle as the cutting edge angle, which is the rotation angle of the spindle 200 at which the diameter of the tool 300 is maximum as seen from the imaging unit 10. Note that the calculation unit 40 may determine any rotation angle within the range of the first angle or more and the second angle or less as the cutting edge angle. Thereby, the attachment angle of the tool 300 with respect to the spindle 200 is detected.

[0034] In step S120, the control unit 20 rotates the spindle 200 and the tool 300 around the spindle rotation axis AX and processes the workpiece using the tool 300.

[0035] In step S130, the control unit 20 rotates the spindle 200 so that the rotation angle of the spindle 200 becomes the fifth angle. In other words, the control unit 20 rotates the tool 300 around the spindle rotation axis AX so that the rotation angle of the spindle 200 becomes the fifth angle. The fifth angle is the rotation angle of the spindle 200 at which the part of the tool 300 that the operator desires to check faces the imaging unit 10. Specifically, the fifth angle is the rotation angle of the spindle 200 at which the part of the tool 300 that the operator desires to check faces the camera 11. For example, when the tool 300 is a two-flute ball end mill, the fifth angle is an angle equal to the cutting edge angle, an angle obtained by rotating the tool 300 by 180° from the cutting edge angle, an angle obtained by rotating the tool 300 by 90° from the cutting edge angle, and the like. The fifth angle is input to the arithmetic unit 30 by the operator via the input device 35. Note that the fifth angle may be stored in the memory 32 in advance.

[0036] In step S140, the imaging unit 10 images the tool 300 when the rotation angle is the fifth angle. At this time, the imaging unit 10 images the tool 300 without turning on the backlight 12. Thereby, the cutting edge of the tool 300 facing the camera 11 when the rotation angle is the fifth angle is imaged. Hereinafter, the case where the tool 300 is a two-flute ball end mill will be described as an example. When the fifth angle is an angle equal to the cutting edge angle, the operator can check the rake face of the first cutting edge of the tool 300 after machining the workpiece. When the fifth angle is an angle obtained by rotating the tool 300 by 180° from the cutting edge angle, the operator can check the rake face of the second cutting edge of the tool 300 after machining the workpiece. When the fifth angle is an angle obtained by rotating the tool 300 by 90° from the cutting edge angle, the operator can check the flank face of the first cutting edge of the tool 300 after machining the workpiece. As described above, the tool angle detection process is executed.

[0037] According to the first embodiment described above, the imaging process, the arithmetic process, and the change process are repeatedly executed until the difference between the first diameter and the second diameter becomes less than a first value which is a predetermined value, and based on the first angle and the second angle of the imaging process executed last, the attachment angle of the tool 300 with respect to the main shaft 200 is detected. Therefore, compared with the method of detecting the attachment angle of the tool 300 with respect to the main shaft 200 by rotating the tool 300 with a high angular resolution, imaging the tool 300 at each rotation angle, and calculating the diameter of the tool 300 as seen from the imaging unit 10 at each rotation angle, the attachment angle can be detected in a short time. For example, the case of detecting the attachment angle of a two-flute tool 300 attached to a main shaft 200 with an angular resolution of 1° will be described as an example. In this case, from Equation (1), the angle of the search range is 180°. When the tool 300 is rotated by 1° each time and the diameter of the tool 300 as seen from the imaging unit 10 at each rotation angle is calculated, 180 rotations, imaging, and diameter calculations of the tool 300 are required. In this case, the cutting edge angle is the angle at which the diameter of the tool 300 as seen from the imaging unit 10 becomes the maximum among 180 rotation angles. On the other hand, in the tool angle detection method of this embodiment, by repeating the imaging process, the arithmetic process, and the change process 13 times, the difference between the first angle and the second angle of the imaging process executed last becomes less than 1°. In this case, a total of 30 rotations, imaging, and diameter calculations of the tool 300 are performed. The cutting edge angle is, for example, the average value of the first angle and the second angle of the imaging process executed last. As described above, in the tool angle detection method of this embodiment, the attachment angle of the tool 300 with respect to the main shaft 200 can be detected in a short time. Note that the angular resolution of the main shaft 200 is also referred to as the main shaft indexing resolution.

[0038] Also, in this embodiment, when the third diameter and the fourth diameter are larger than the first diameter and the third diameter and the fourth diameter are larger than the second diameter, the search range is shifted by an angle that is half of the search range. In the "search range before shift" shown in FIG. 6, the third diameter and the fourth diameter are larger than the first diameter, and the third diameter and the fourth diameter are larger than the second diameter. In the example shown in FIG. 6, since the cutting edge angle is a value close to the fourth angle in the "search range before shift", the accurate cutting edge angle cannot be detected even if the imaging process, the arithmetic process, and the change process are repeated. However, by shifting the search range by an angle that is half of the search range, at least one of the third diameter and the fourth diameter becomes smaller than the first diameter, or at least one of the third diameter and the fourth diameter becomes smaller than the second diameter. In the "search range after shift" shown in FIG. 6, the third diameter and the fourth diameter are smaller than the first diameter, and the third diameter and the fourth diameter are smaller than the second diameter. Thereby, the cutting edge angle can be detected by repeating the imaging process, the arithmetic process, and the change process. Therefore, even if the attachment angle of the tool 300 with respect to the main shaft 200 cannot be detected by repeating the imaging process, the arithmetic process, and the change process in the initially determined search range, the attachment angle of the tool 300 with respect to the main shaft 200 can be detected by shifting the search range. Also, by shifting the search range by an angle that is half of the search range, the search range can be changed to a range in which the attachment angle of the tool 300 with respect to the main shaft 200 can be detected by repeating the imaging process, the arithmetic process, and the change process by shifting the search range once.

[0039] Also, in this embodiment, after the workpiece is machined using the tool 300 attached to the main shaft 200, the tool 300 when the rotation angle is the fifth angle is imaged by the imaging unit 10. Therefore, the state of the tool 300 can be confirmed after the workpiece is machined using the tool 300.

[0040] Also, in this embodiment, the difference between the third angle and the first angle, the difference between the first angle and the second angle, and the difference between the second angle and the fourth angle are equal. Therefore, the angle of the search range can be reduced to two-thirds each time the imaging process, the arithmetic process, and the change process are repeated once.

[0041] In addition, in the present embodiment, even when the imaging process, the arithmetic process, and the change process are repeated a predetermined number of times, if the difference between the first diameter and the second diameter does not become less than the first value, the tool angle detection process ends. Therefore, it is possible to suppress the continuous execution of the tool angle detection process.

[0042] In addition, in the present embodiment, the tool 300 has blades provided rotationally symmetrically about its axis. That is, the blades are provided periodically at substantially equal intervals on the outer periphery of the tool 300. The arithmetic unit 40 determines the search range based on the number of blades of the tool 300 attached to the main shaft 200 as shown in Equation (1). The diameter of the tool 300 as seen from the imaging unit 10 at an arbitrary rotation angle included in this search range is equal to the diameter of the tool 300 as seen from the imaging unit 10 at the rotation angle obtained by adding (360° / number of blades) to the rotation angle. In the tool angle detection process, the attachment angle of the tool 300 with respect to the main shaft 200 is detected using the diameter of the tool 300 as seen from the imaging unit 10 at the rotation angles included in the search range described above. Therefore, the attachment angle of the tool 300 with respect to the main shaft 200 can be efficiently detected.

[0043] B. Second Embodiment: In the second embodiment, the difference between the third angle and the first angle, the difference between the first angle and the second angle, and the difference between the second angle and the fourth angle are different from those in the first embodiment. The content of the tool angle detection process and the configuration of each part of the tool angle detection device 100 other than the above-described content are the same as those in the first embodiment.

[0044] FIG. 8 is a diagram showing an example of the relationship between the rotation angle of the main shaft 200 and the diameter of the tool 300 as seen from the imaging unit 10 in the second embodiment. In the second embodiment, the ratio of the difference between the third angle and the first angle and the difference between the first angle and the fourth angle is the golden ratio, and the ratio of the difference between the second angle and the fourth angle and the difference between the third angle and the second angle is the golden ratio. When the third angle is A and the fourth angle is B, the first angle M1 and the second angle M2 in the third embodiment are calculated by the following equations (6) and (7), respectively. M1=(A - B) / GoldenRatio + B ···(6) M2 = (A - B) / (1 + GoldenRatio) + B ···(7)

[0045] According to the second embodiment described above, in step S90 of the tool angle detection process, when the calculation unit 40 changes the search range from the range of the third angle or more and the fourth angle or less to the range of the third angle or more and the second angle or less, the second angle in the search range before the change becomes the fourth angle in the search range after the change, and the first angle in the search range before the change becomes the second angle in the search range after the change. The third angle does not change before and after the change of the search range. Also, when the calculation unit 40 changes the search range from the range of the third angle or more and the fourth angle or less to the range of the first angle or more and the fourth angle or less, the first angle in the search range before the change becomes the third angle in the search range after the change, and the second angle in the search range before the change becomes the first angle in the search range after the change. The fourth angle does not change before and after the change of the search range. Therefore, compared with the first embodiment, the number of times the imaging unit 10 images the tool 300 and the number of times the calculation unit 40 calculates the diameter of the tool 300 can be reduced.

[0046] C. Third Embodiment: In the third embodiment, the difference between the third angle and the first angle, the difference between the first angle and the second angle, and the difference between the second angle and the fourth angle are different from those in the first embodiment. The content of the tool angle detection process and the configuration of each part of the tool angle detection device 100 other than the above-described content are the same as those in the first embodiment.

[0047] In the third embodiment, the difference between the third angle and the fourth angle is the third value that is a value included in the Fibonacci sequence, the difference between the third angle and the first angle, and the difference between the second angle and the fourth angle are values that are two smaller than the third value among the values included in the Fibonacci sequence, and the difference between the third angle and the second angle is a value that is one smaller than the third value among the values included in the Fibonacci sequence.

[0048] FIG. 9 is a diagram showing an example of the relationship between the rotation angle of the spindle 200 and the diameter of the tool 300 as viewed from the imaging unit 10 in the third embodiment. In the third embodiment, in step S10 of the tool angle detection process, the calculation unit 40 determines the search range such that the angle of the search range is the smallest value greater than (360° / number of blades) among the values included in the Fibonacci sequence. For example, when the number of blades of the tool 300 attached to the spindle 200 is 2, the calculation unit 40 determines the search range such that the difference between the third angle and the fourth angle is 233°. At this time, the difference between the third angle and the first angle, and the difference between the second angle and the fourth angle are 89°, and the difference between the third angle and the second angle is 144°. When step S90 of the tool angle detection process is executed in the above-described example and the search range is changed from the range of the third angle or more and the fourth angle or less to the range of the third angle or more and the second angle or less, the difference between the third angle and the fourth angle in the changed search range is 144°, the difference between the third angle and the first angle, and the difference between the second angle and the fourth angle are 55°, and the difference between the third angle and the second angle is 89°.

[0049] According to the third embodiment described above, even if the search range is changed, since the first angle, the second angle, the third angle, and the fourth angle are always integers, when the angular resolution of the spindle 200 is an integer, the attachment angle of the tool 300 to the spindle 200 can be detected in a short time.

[0050] D. Other Embodiments: (D-1) In the above-described embodiment, in step S80 of the tool angle detection process shown in FIG. 3, the calculation unit 40 determines whether or not the difference between the first diameter and the second diameter calculated in step S70 is less than a first value which is a predetermined value. In contrast, in step S80, the calculation unit 40 may determine whether or not the difference between the first angle and the second angle, which is the rotation angle at which the tool 300 was imaged in step S60, is less than a second value which is a predetermined value. The difference between the first angle and the second angle is represented by ΔM in FIGS. 4 and 7. The second value is preferably a value close to 0. The second value is, for example, 1° or 0.1°. When the difference between the first angle and the second angle is equal to or greater than the second value, step S90 is executed. When the difference between the first angle and the second angle is less than the second value, step S110 is executed. That is, the imaging process, the calculation process, and the change process are repeatedly executed until the difference between the first angle and the second angle becomes less than the second value.

[0051] (D-2) In the above-described embodiment, the direction along the main shaft rotation axis AX is the vertical direction. In contrast, the direction along the main shaft rotation axis AX may be a direction other than the vertical direction.

[0052] (D-3) In the above-described embodiment, in step S50 of the tool angle detection process, the calculation unit 40 shifts the search range by an angle that is half of the search range. In contrast, the calculation unit 40 may shift the search range by an arbitrary angle. In this case, the calculation unit 40 may shift the search range a plurality of times in step S50.

[0053] (D-4) In the above-described embodiment, the calculation unit 40 shifts the search range in step S50 of the tool angle detection process. In contrast, the calculation unit 40 may not shift the search range. That is, steps S20 to S50 of the tool angle detection process may not be executed.

[0054] (D-5) In the above embodiment, the control unit 20 processes the workpiece using the tool 300 in step S120 of the tool angle detection process, and rotates the spindle 200 so that the rotation angle of the spindle 200 becomes the fifth angle in step S130. Further, in step S140 of the tool angle detection process, the imaging unit 10 images the tool 300 when the rotation angle is the fifth angle. In contrast, the control unit 20 does not necessarily process the workpiece using the tool 300, nor does it necessarily rotate the spindle 200 so that the rotation angle of the spindle 200 becomes the fifth angle. Further, the imaging unit 10 does not necessarily image the tool 300 when the rotation angle is the fifth angle. That is, steps S120 to S140 of the tool angle detection process do not necessarily have to be executed.

[0055] (D-6) In the above embodiment, the calculation unit 40 ends the tool angle detection process in step S100 of the tool angle detection process when the difference between the first diameter and the second diameter does not become less than the first value even if the imaging process, the calculation process, and the change process are repeated a predetermined number of times. In contrast, the calculation unit 40 does not necessarily end the tool angle detection process when the difference between the first diameter and the second diameter does not become less than the first value even if the imaging process, the calculation process, and the change process are repeated a predetermined number of times. That is, step S100 of the tool angle detection process does not necessarily have to be executed.

[0056] (D-7) In the above embodiment, the tool 300 has blades provided rotationally symmetrically about its axis. In contrast, the tool 300 does not necessarily have blades provided rotationally symmetrically about its axis. The tool 300 may be, for example, a single-edge end mill or drill.

[0057] The present disclosure is not limited to the above-described embodiments, and can be realized in various configurations without departing from the gist thereof. For example, the technical features in the embodiments corresponding to the technical features in each form described in the summary of the invention can be appropriately replaced or combined in order to solve some or all of the above-described problems, or to achieve some or all of the above-described effects. Further, if the technical feature is not described as essential in this specification, it can be appropriately deleted.

Description of Reference Numerals

[0058] AX... Main spindle rotation axis, 10... Imaging unit, 11... Camera, 12... Backlight, 20... Control unit, 30... Arithmetic unit, 31... CPU, 32... Memory, 33... Input / output interface, 34... Internal bus, 35... Input device, 36... Display device, 40... Arithmetic section, 100... Tool angle detection device, 200... Main spindle, 210... Servo motor, 220... Drive circuit, 300... Tool

Claims

1. A tool angle detection method for detecting the attachment angle of a tool with respect to a spindle, comprising: (a) determining a search range, which is a range of the rotation angle of the spindle, based on the number of cutting edges of the tool attached to the spindle; (b) imaging the tool when the rotation angle is a first angle and the tool when the rotation angle is a second angle with an imaging unit from a direction intersecting the axis of the spindle, wherein the first angle is greater than a third angle that is the minimum angle within the search range and less than a fourth angle that is the maximum angle within the search range, and the second angle is greater than the first angle and less than the fourth angle; (c) calculating, using the image captured in step (b), a first diameter that is the diameter of the tool as seen from the imaging unit when the rotation angle is the first angle and a second diameter that is the diameter of the tool as seen from the imaging unit when the rotation angle is the second angle; (d) when the first diameter is greater than the second diameter, changing the search range to a range greater than or equal to the third angle and less than or equal to the second angle, and when the first diameter is less than the second diameter, changing the search range to a range greater than or equal to the first angle and less than or equal to the fourth angle; repeating steps (b) to (d) until the difference between the first diameter and the second diameter is less than a first value that is a predetermined value, or until the difference between the first angle and the second angle is less than a second value that is a predetermined value; and finally detecting the attachment angle of the tool with respect to the spindle based on the first angle and the second angle in the last-executed step (b). Tool angle detection method.

2. The tool angle detection method according to claim 1, further comprising: in step (b), imaging the tool when the rotation angle is the third angle and the tool when the rotation angle is the fourth angle with the imaging unit; in step (c), calculating, using the image captured in step (b), a third diameter that is the diameter of the tool as seen from the imaging unit when the rotation angle is the third angle and a fourth diameter that is the diameter of the tool as seen from the imaging unit when the rotation angle is the fourth angle; (e) further comprising a step of shifting the search range when the third diameter and the fourth diameter are greater than the first diameter and the third diameter and the fourth diameter are greater than the second diameter. Tool angle detection method.

3. The tool angle detection method according to claim 2, in the step (e), shifting the search range by an angle that is half of the search range; Tool angle detection method.

4. The tool angle detection method according to claim 1, (f) after the workpiece is machined using the tool, rotating the tool around the axis of the spindle so that the rotation angle becomes a fifth angle at which a part of the tool that an operator desires to check faces the imaging unit; (g) further comprising the step of imaging the tool when the rotation angle is the fifth angle by the imaging unit. Tool angle detection method.

5. The tool angle detection method according to claim 1, the difference between the third angle and the first angle, the difference between the first angle and the second angle, and the difference between the second angle and the fourth angle are equal; Tool angle detection method.

6. The tool angle detection method according to claim 1, the ratio of the difference between the third angle and the first angle to the difference between the first angle and the fourth angle is the golden ratio, and the ratio of the difference between the second angle and the fourth angle to the difference between the third angle and the second angle is the golden ratio; Tool angle detection method.

7. The tool angle detection method according to claim 1, the difference between the third angle and the fourth angle is a third value that is a value included in the Fibonacci sequence; the difference between the third angle and the first angle, and the difference between the second angle and the fourth angle are values that are two smaller than the third value among the values included in the Fibonacci sequence; the difference between the third angle and the second angle is a value that is one smaller than the third value among the values included in the Fibonacci sequence. Tool angle detection method.

8. The tool angle detection method according to claim 1, even if the steps (b) to (d) are repeated a predetermined number of times, when the difference between the first diameter and the second diameter does not become less than the first value and the difference between the first angle and the second angle does not become less than the second value, ending the process of detecting the mounting angle. Tool angle detection method.

9. A tool angle detection device for detecting the mounting angle of a tool with respect to a spindle, a control unit that rotates the tool attached to the spindle around the axis of the spindle by changing the rotation angle of the spindle; an imaging unit that images the tool attached to the spindle from a direction intersecting the axis of the spindle; and a calculation unit. The calculation unit determines a search range, which is a range of the rotation angle, based on the number of cutting edges of the tool. The imaging unit executes an imaging process of imaging the tool when the rotation angle is the first angle, which is greater than a third angle that is the minimum angle within the search range and less than a fourth angle that is the maximum angle within the search range, and the second angle, which is greater than the first angle and less than the fourth angle, and imaging the tool when the rotation angle is the second angle. The calculation unit executes a calculation process of calculating a first diameter, which is the diameter of the tool as seen from the imaging unit when the rotation angle is the first angle, and a second diameter, which is the diameter of the tool as seen from the imaging unit when the rotation angle is the second angle, using the image captured by the imaging unit. When the first diameter is larger than the second diameter, the search range is changed to a range of equal to or greater than the third angle and equal to or less than the second angle, and when the first diameter is smaller than the second diameter, a change process of changing the search range to a range of equal to or greater than the first angle and equal to or less than the fourth angle is executed. The tool angle detection device repeatedly executes the imaging process, the calculation process, and the change process until the difference between the first diameter and the second diameter becomes less than a first value that is a predetermined value, or until the difference between the first angle and the second angle becomes less than a second value that is a predetermined value. The calculation unit detects the attachment angle of the tool with respect to the main shaft based on the first angle and the second angle in the last executed imaging process. Tool angle detection device.

Images