Cutting machine and method for correcting coordinates for cutting machine

Abstract

This method for correcting coordinates for a cutting machine includes: a first contact process in which a spindle (30) is moved in an X-axis direction, whereby a detection tool (31) held by the spindle (30) is brought into contact with a pin (32) held by a clamp (50), and a first contact position is acquired; a first movement process in which the clamp (50) is moved by a first distance in a Y-axis direction; a second contact process in which, after the first movement process, the spindle (30) is moved in the X-axis direction, whereby the detection tool (31) is brought into contact with the pin (32), and a second contact position is acquired; and a correction process in which, on the basis of the first contact position, the second contact position, and the first distance, the positional coordinates are corrected so that the Y axis is perpendicular to an A axis as seen from a Z axis.

Description

Cutting machine and coordinate correction method for cutting machine

[0001] The present invention relates to a cutting machine and a coordinate correction method for the cutting machine.

[0002] Conventionally, as an apparatus for producing, for example, artificial teeth and denture bases, cutting machines have been known in which a processing tool is moved linearly relative to a workpiece in the X-axis, Y-axis, and Z-axis directions and rotated relative to the workpiece around the A-axis (see, for example, JP 2020-28966 A). Here, the X-axis, Y-axis, and Z-axis are mutually perpendicular, and the A-axis is an axis parallel to the X-axis. Moving the processing tool linearly relative to the workpiece in the X-axis, Y-axis, and Z-axis directions means moving one of the processing tool and the workpiece linearly relative to the other, or moving both linearly, in the X-axis, Y-axis, and Z-axis directions, respectively. Rotating the processing tool relative to the workpiece around the A-axis means rotating one or both of the processing tool and the workpiece around the A-axis.

[0003] Japanese Patent Application Laid-Open No. 2020-28966

[0004] In cutting machines, each axis may tilt from its normal direction due to component assembly errors, aging, and other factors. In these cutting machines, the machining tool rotates around the A-axis relative to the workpiece, so tilting an axis perpendicular to the A-axis is likely to result in machining errors. That is, as shown in FIG. 21 , if the Y-axis tilts, moving the machining tool along the Y-axis will result in the tool moving in a direction tilted from the A-axis (see dashed arrow) instead of the intended direction perpendicular to the A-axis (see solid arrow). This results in position coordinate errors. Furthermore, position coordinate errors also occur when rotating the workpiece around the A-axis. Therefore, in such cutting machines, reducing position coordinate errors caused by Y-axis tilt is effective in improving machining accuracy.

[0005] The present invention has been made in view of the above points, and an object of the present invention is to improve the machining accuracy of a cutting machine in which a machining tool is moved linearly relative to a workpiece in the directions of the X-axis, Y-axis, and Z-axis, and rotated relative to the workpiece about the A-axis.

[0006] The coordinate correction method for a cutting machine disclosed herein is a method for correcting position coordinates of a cutting machine that includes a first holding member that holds a workpiece, a second holding member that holds a processing tool that cuts the workpiece, and a drive device that drives at least one of the first holding member and the second holding member to move the processing tool straight relative to the workpiece in the directions of the X-axis, Y-axis, and Z-axis that are perpendicular to each other, and to rotate the workpiece relative to the processing tool around the A-axis that is parallel to the X-axis. The correction method includes: an attachment process for attaching a correction jig to the first holding member and attaching a detection tool to the second holding member, the detection tool detecting contact with the correction jig; a first contact process for moving the second holding member relative to the first holding member in the X-axis direction, thereby bringing the detection tool held by the second holding member into contact with the correction jig held by the first holding member, and acquiring a first contact position; a first movement process for moving the second holding member a first distance in the Y-axis direction relative to the first holding member; a second contact process for moving the second holding member relative to the first holding member in the X-axis direction, after the first movement process, thereby bringing the detection tool held by the second holding member into contact with the correction jig held by the first holding member, and acquiring a second contact position; and a correction process for correcting position coordinates based on at least the first contact position, the second contact position, and the first distance, so that the Y-axis is perpendicular to the A-axis when viewed from the Z-axis.

[0007] According to the above correction method, the position coordinates are corrected so that the Y axis is perpendicular to the A axis when viewed from the Z axis, so even if the Y axis is tilted from the correct direction due to an assembly error in the parts of the cutting machine or deterioration over time, no error in the position coordinates occurs when the processing tool is moved straight in the Y axis direction relative to the workpiece or when the processing tool is rotated around the A axis relative to the workpiece, thereby improving processing accuracy.

[0008] According to the present invention, the machining accuracy of a cutting machine can be improved.

[0009] FIG. 1 is a perspective view of a cutting machine according to an embodiment. FIG. 2 is a front view of the cutting machine with the front cover open. FIG. 3 is a vertical cross-sectional view of the cutting machine. FIG. 4 is a perspective view of a clamp, a carriage, and a tool magazine. FIG. 5 is a block diagram of a control system of the cutting machine. FIG. 6 is a view of the clamp, the carriage, and the tool magazine as viewed from the Y-axis. FIG. 7 is a perspective view of a workpiece attached to a holder. FIG. 8 is a functional block diagram of a correction device according to a first embodiment. FIG. 9 is a diagram illustrating coordinate errors caused by tilt of the Y-axis. FIG. 10 is a flowchart of a coordinate correction method according to a first embodiment. FIG. 11 is a diagram illustrating contact between a detection tool and a pin in a first contact process. FIG. 12 is a diagram illustrating contact between a detection tool and a pin in a second contact process. FIG. 13 is a diagram illustrating the tilt angle of the Y-axis with respect to a line perpendicular to the A-axis. FIG. 14A is a diagram illustrating contact between a detection tool and a pin when the tip of the pin is flat. FIG. 14B is a diagram illustrating contact between a detection tool and a pin when the tip of the pin is flat. FIG. 14C is a diagram showing contact between a detection tool and a pin when the tip of the pin is curved. FIG. 14D is a diagram showing contact between a detection tool and a pin when the tip of the pin is curved. FIG. 15 is a flowchart of a coordinate correction method according to a second embodiment. FIG. 16 is a diagram explaining contact between a detection tool and a pin in the first contact process and the third contact process. FIG. 17 is a diagram explaining contact between a detection tool and a pin in the second contact process and the fourth contact process. FIG. 18 is a functional block diagram of a correction device according to the second embodiment. FIG. 19 is a diagram showing another example of a correction jig. FIG. 20 is a diagram showing another example of a correction jig. FIG. 21 is a diagram explaining a coordinate error caused by tilt of the Y-axis.

[0010] Hereinafter, an embodiment of a cutting machine and a coordinate correction method for the cutting machine will be described with reference to the drawings. The cutting machine described below is a dental cutting machine that produces dental molded products. The cutting machine cuts, for example, crown prostheses, artificial teeth, denture bases, etc.

[0011] Fig. 1 is a perspective view of a cutting machine 10 according to this embodiment. Fig. 2 is a front view of the cutting machine 10 with the front cover 20 open. Fig. 3 is a vertical cross-sectional view of the cutting machine 10. In the following description, when the cutting machine 10 is viewed from the front, the side away from the cutting machine 10 is referred to as the front, and the side approaching the cutting machine 10 is referred to as the rear. The terms left, right, top, and bottom refer to the left, right, top, and bottom, respectively, when the cutting machine 10 is viewed from the front.

[0012] The cutting machine 10 controls the cutting operation based on coordinates of the X-axis, Y-axis, Z-axis, and A-axis. As shown in FIG. 1, the X-axis, Y-axis, and Z-axis are mutually orthogonal coordinate axes. Here, the X-axis is an axis extending to the right. As shown in FIG. 3, the Y-axis is an axis extending rearward and downward, and the Z-axis is an axis extending upward and rearward. As shown in FIG. 2, the A-axis is an axis parallel to the X-axis. The A-axis is an axis orthogonal to the Y-axis and Z-axis. In this specification, the coordinate of the A-axis refers to the rotation angle around the A-axis. A position related to control in the cutting machine 10 (for example, the position of the tip of the machining tool 6 described below) is specified by four parameters: the coordinate of the X-axis, the coordinate of the Y-axis, the coordinate of the Z-axis, and the rotation angle around the A-axis.

[0013] As shown in FIG. 1 , the cutting machine 10 includes a box-shaped case 11. The case 11 includes a case main body 12 and a front cover 20 attached to the case main body 12 so as to be vertically slidable. As shown in FIG. 2 , the cutting machine 10 includes a spindle 30 that holds a processing tool 6, a clamp 50, and a drive unit 25 that drives the spindle 30 and the clamp 50. As shown in FIG. 4 , the clamp 50 is a member that holds a workpiece 5 and is an example of a "first holding member." As shown in FIG. 3 , the spindle 30 holds the processing tool 6 rotatably around the Z-axis (the Z-axis here includes an axis parallel to the Z-axis). The spindle 30 is an example of a "second holding member."

[0014] As shown in Fig. 2, the drive device 25 includes a carriage 38Z to which the spindle 30 is attached, and a carriage 38X to which the carriage 38Z is attached. Furthermore, as shown in Fig. 5, the drive device 25 includes a Z-axis motor 26Z that moves the carriage 38Z in the Z-axis direction, and an X-axis motor 26X that moves the carriage 38X in the X-axis direction. The Z-axis motor 26Z and the X-axis motor 26X are electrically connected to and controlled by the control device 90.

[0015] As shown in FIG. 2, the carriage 38X is slidably supported by a pair of guide shafts 39A extending in the X-axis direction. The carriage 38Z is slidably supported by a pair of guide shafts 39B extending in the Z-axis direction. The guide shafts 39B are fixed to the carriage 38X. When the carriage 38X moves in the X-axis direction, the carriage 38Z also moves in the X-axis direction. The spindle 30 is fixed to the carriage 38Z. Therefore, the spindle 30 moves in the Z-axis direction in conjunction with the movement of the carriage 38Z, and moves in the X-axis direction in conjunction with the movement of the carriage 38X.

[0016] As shown in Fig. 6, the drive device 25 includes a rotary shaft 38A extending in the A-axis direction, a rotary motor 26A (see Fig. 5) that rotates the rotary shaft 38A around the A-axis, a carriage 38Y to which the rotary shaft 38A is attached, and a Y-axis motor 26Y (see Fig. 5) that moves the carriage 38Y in the Y-axis direction. The A-axis coincides with the rotation center line of the rotary shaft 38A. The rotary motor 26A and the Y-axis motor 26Y are electrically connected to and controlled by a control device 90.

[0017] When the carriage 38Y moves in the Y-axis direction, the rotation shaft 38A also moves in the Y-axis direction. The clamp 50 is fixed to the rotation shaft 38A. Therefore, the clamp 50 moves in the Y-axis direction in conjunction with the movement of the carriage 38Y, and rotates around the A-axis in conjunction with the rotation of the rotation shaft 38A.

[0018] As shown in Fig. 4, a tool magazine 40 is provided on the carriage 38Y. The tool magazine 40 accommodates a plurality of machining tools 6. The tool magazine 40 has a plurality of holes 42 (six in this example) formed therein for accommodating the machining tools 6. The machining tools 6 are inserted into the holes 42 with their upper portions exposed.

[0019] Although the clamp 50 may be configured to directly hold the workpiece 5, in this embodiment it is configured to indirectly hold the workpiece 5. FIG. 7 is a perspective view of the workpiece 5 attached to the holder 8. The clamp 50 detachably holds the holder 8. The clamp 50 indirectly holds the workpiece 5 via the holder 8. The clamp 50 has multiple insertion holes 50A formed therein (see FIGS. 3 and 6). Here, three insertion holes 50A are aligned in the Y-axis direction. The connecting pins 8B of the holder 8 are inserted into the insertion holes 50A. The connecting pins 8B inserted into the insertion holes 50A are fixed to the clamp 50 by screws 50B.

[0020] The control device 90 is configured by a computer. The control device 90 includes, for example, a central processing unit (CPU) that executes instructions of a control program, a read-only memory (ROM) that stores programs executed by the CPU, a random access memory (RAM) used as a working area for expanding the programs, and a recording medium such as a memory that stores various data. The control device 90 is configured to control cutting processing by, for example, executing a program stored in the ROM. In this embodiment, the control device 90 is disposed inside the case 11 (see FIG. 1 ). The control device 90 is a dedicated computer built into the cutting machine 10. However, part or all of the control device 90 may be a computer disposed outside the case 11. Part or all of the control device 90 may be a general-purpose computer (e.g., a desktop computer) electrically connected to the cutting machine 10.

[0021] The position of the machining tool 6 relative to the workpiece 5 is specified by the X-axis coordinate, the Y-axis coordinate, the Z-axis coordinate, and the rotation angle around the A-axis. In this embodiment, the machining tool 6 is movable in the X-axis and Z-axis directions, and the workpiece 5 is movable in the Y-axis direction and rotatable around the A-axis. The position of the machining tool 6 can be specified by the X-axis coordinate and the Z-axis coordinate. The position of the workpiece 5 can be specified by the Y-axis coordinate and the rotation angle around the A-axis. Note that the machining tool 6 moves together with the spindle 30, and the workpiece 5 moves together with the clamp 50. Therefore, as positions related to control of the cutting machine 10, the position of the spindle 30 may be used instead of the position of the machining tool 6, and the position of the clamp 50 may be used instead of the position of the workpiece 5.

[0022] The cutting machine 10 is equipped with a correction device 60 that corrects the coordinates of the processing tool 6 and the workpiece 5. The correction device 60 is configured by a computer. FIG. 8 is a functional block diagram of the correction device 60. Part or all of the correction device 60 may be separate from the control device 90, or may be integrated with the control device 90. In this embodiment, the computer that constitutes the control device 90 also serves as the correction device 60. The correction device 60 is equipped with a first contact processing unit 61 that performs a first contact process, a rotation processing unit 63 that performs a rotation process, a movement processing unit 64 that performs a movement process, a second contact processing unit 62 that performs a second contact process, and a correction processing unit 65 that performs a correction process. Each of these processes will be described later.

[0023] The coordinate correction according to this embodiment corrects errors resulting from the tilt of the Y-axis relative to the Z-axis, i.e., coordinate correction in directions parallel to and perpendicular to the A-axis. The Y-axis is essentially an axis perpendicular to the X-axis. However, due to assembly errors or aging of components of the cutting machine 10, the Y-axis may tilt, as exaggeratedly shown in FIG. 9 . When the Y-axis tilts, an error occurs in the angle of the A-axis relative to the Y-axis. That is, the angle of the A-axis relative to the Y-axis deviates from 90 degrees. In the cutting machine 10 according to this embodiment, the clamp 50 rotates around the A-axis and moves linearly in the Y-axis direction. When the Y-axis tilts, for example, the coordinate of the machining position shifts from point P' in FIG. 9 to point P. Therefore, in this embodiment, the coordinate of the machining position is corrected to reduce errors resulting from the tilt of the Y-axis. For example, a process is performed to correct the coordinate of the machining position from point P to point P'. Here, the machining position is a position where the machining tool 6 cuts the workpiece 5, and where the machining tool 6 and the workpiece 5 come into contact with each other.

[0024] In the cutting machine 10, first, the tilt of the Y axis as viewed from the Z axis is detected using a correction jig and a detection tool, and then the coordinates are corrected based on the detected tilt of the Y axis. Next, the coordinate correction method will be described.

[0025] First Embodiment FIG. 10 is a flowchart of a coordinate correction method according to the first embodiment.

[0026] First, in step S1, a correction jig is attached to the clamp 50, and a detection tool is attached to the spindle 30 (attachment process). In this embodiment, as shown in FIG. 11 , a pin 32 is attached to the clamp 50 as a correction jig instead of the workpiece 5. The pin 32 is attached at a position offset in the Y-axis direction from the A-axis (i.e., the rotation center line of the clamp 50). In this embodiment, the pin 32 is a cylindrical pin with a rounded tip. The tip of the pin 32 has a curved surface that is curved at least along the Y-axis direction. Here, the tip of the pin 32 is formed into a spherical shape. The detection tool 31 is formed into a rod shape extending in the Z-axis direction.

[0027] The detection tool 31 is configured to detect contact with the pin 32. Here, the detection tool 31 and the pin 32 are made of a conductor such as iron. A voltage is applied to at least one of the detection tool 31 and the pin 32. The detection tool 31 is configured to pass a current when it comes into contact with the pin 32. The correction device 60 detects the current to detect that the detection tool 31 has come into contact with the pin 32, and detects the positions of the detection tool 31 and the pin 32 at that time. Note that if the processing tool 6 is made of a conductor, the processing tool 6 may be used as the detection tool 31. The detection tool 31 may be a dedicated tool separate from the processing tool 6, or may be the processing tool 6.

[0028] Next, the process proceeds to step S2, where a first contact process is performed. In the first contact process, the detection tool 31 is first moved in the X-axis direction to bring the detection tool 31 into contact with the pin 32 (see FIG. 11 ). Then, the position P11 (x11, y11) at this time is detected as the first contact position. Thereafter, the detection tool 31 is moved away from the pin 32.

[0029] Next, the process proceeds to step S3, where a rotation process is performed. In the rotation process, the clamp 50 is rotated 180 degrees around the A axis. Next, the process proceeds to step S4, where a movement process is performed. Here, the tip of the pin 32 is positioned at a distance L (see FIG. 11) from the A axis. Therefore, in the movement process, the clamp 50 is moved by 2L in the Y axis direction. As a result, the pin 32 is positioned to the side of the detection tool 31 (see the dashed line in FIG. 12).

[0030] Next, the process proceeds to step S5, where a second contact process is performed. As in the first contact process, in the second contact process, the detection tool 31 is moved in the X-axis direction to contact the pin 32 (see FIG. 12). Then, the position P12 (x12, y12) at this time is detected as the second contact position. Thereafter, the detection tool 31 is moved away from the pin 32.

[0031] Next, the process proceeds to step S6, where a correction process is executed. In the correction process, the coordinates are corrected based on the first contact position P11, the second contact position P12, and the movement distance 2L in the movement process so that the tilt of the Y axis with respect to the perpendicular to the A axis as viewed from the Z axis is eliminated. For example, as shown in FIG. 13, if the tilt angle of the Y axis with respect to the perpendicular to the A axis is θ, then sin θ = (x12 - x11) / 2L. Since θ is a small angle, it can be considered that sin θ is approximately θ. Therefore, it can be calculated as θ = (x12 - x11) / 2L. In this way, the tilt of the Y axis with respect to the perpendicular to the A axis can be detected, and the position coordinates can be corrected based on the tilt of the Y axis. For example, the corrected coordinate P'(x', y') for the coordinate P(x, y) can be calculated by calculating x' = (x ２ +y ２ ) ０．５ ×sinθ,y'=(x ２ +y ２ ) ０．５ ×cos θ.

[0032] The above is the coordinate correction method for the cutting machine 10. When performing cutting, the workpiece 5 is attached to the clamp 50, and the machining tool 6 is attached to the spindle 30. The control device 90 controls the positions of the machining tool 6 and the clamp 50 based on the corrected coordinates. This allows cutting to be performed with high precision even if the Y-axis is tilted.

[0033] In the above method, the movement distance in the Y-axis direction during the movement process is calculated assuming it is equal to a predetermined distance 2L. However, the movement distance may also be detected based on contact between the detection tool 31 and the pin 32 in the Y-axis direction. For example, before or after the first contact process, the clamp 50 is moved in the Y-axis direction to bring the detection tool 31 and the pin 32 into contact, and the distance L1 between the center line of the pin 32 and the A-axis before the clamp 50 is rotated is detected. Also, before or after the second contact process, the clamp 50 is moved in the Y-axis direction to bring the detection tool 31 and the pin 32 into contact, and the distance L2 between the center line of the pin 32 and the A-axis after the clamp 50 is rotated is detected. This allows the movement distance in the Y-axis direction to be detected as L1 + L2. In this case, the tilt angle θ of the Y-axis can be calculated as θ = (x12 - x11) / (L1 + L2).

[0034] As described above, according to this embodiment, in the cutting machine 10 that controls cutting operations based on the X-, Y-, Z-, and A-axes, the tilt of the Y-axis with respect to the perpendicular to the A-axis as viewed from the Z-axis is detected, and the coordinates are corrected to eliminate the tilt. Therefore, even if the Y-axis is tilted from the correct direction due to component assembly errors or aging, no coordinate errors occur when the clamp 50 is moved in a straight line along the Y-axis or rotated around the A-axis. This improves machining accuracy.

[0035] According to this embodiment, between the first contact process and the second contact process, a rotation process is performed to rotate the clamp 50 around the A axis, and a movement process is performed to move the clamp 50 in a straight line in the Y axis direction (see FIG. 10 ). Therefore, the first contact process and the second contact process can be performed using the same pin 32 as the pin with which the detection tool 31 makes contact. If different pins are used in the first contact process and the second contact process, there is a risk of reduced correction accuracy due to dimensional errors between the pins. However, by using the same pin 32 as in this embodiment, the tilt of the Y axis can be detected more accurately.

[0036] As shown in an exaggerated manner in Figures 14A and 14B, if the tip of the pin 32 is flat, and the pin 32 is tilted, the position of the contact point between the detection tool 31 and the pin 32 in the X-axis direction may shift between the first contact process and the second contact process, even if the Y-axis is not tilted. However, according to this embodiment, the tip of the pin 32 has a curved surface that is curved at least along the Y-axis direction. Therefore, as shown in an exaggerated manner in Figures 14C and 14D, even if the pin 32 is tilted, the position of the contact point between the detection tool 31 and the pin 32 in the X-axis direction is unlikely to shift between the first contact process and the second contact process. Therefore, errors caused by the tilt of the pin 32 can be reduced, and the tilt of the Y-axis can be detected with high accuracy.

[0037] Second Embodiment The correction method according to the first embodiment is a method in which the detection tool is brought into contact with only one location on the correction jig when detecting the tilt of the Y axis. The correction method according to the second embodiment is a method in which the detection tool is brought into contact with multiple locations on the correction jig when detecting the tilt of the Y axis. Figure 15 is a flowchart of the coordinate correction method according to the second embodiment.

[0038] 16 , in this embodiment, a first pin 32A and a second pin 32B are attached to a clamp 50 as a correction jig. The first pin 32A and the second pin 32B are attached at positions offset in the Y-axis direction from the A-axis. Like the pin 32 according to the first embodiment, the first pin 32A and the second pin 32B are cylindrical, conductive pins with rounded tips.

[0039] First, in step S11, the first pin 32A and the second pin 32B are attached to the clamp 50, and the detection tool 31 is attached to the spindle 30 (attachment process).

[0040] Next, proceed to step S12, where the detection tool 31 is moved in the X-axis direction to bring the detection tool 31 into contact with the first pin 32A (first contact process; see arrow B1 in FIG. 16). Then, position P11 (x11, y11) at this time is detected as the first contact position. The first pin 32A is an example of the first part of the correction jig. Then, the detection tool 31 is moved away from the first pin 32A.

[0041] Next, the process proceeds to step S13, where the clamp 50 is moved by -2L in the Y-axis direction (first movement process). This positions the detection tool 31 to the side of the second pin 32B. Thereafter, the process proceeds to step S14, where the detection tool 31 is moved in the X-axis direction to contact the second pin 32B (third contact process; see arrow B3 in Figure 16). The position P21 (x21, y21) at this time is detected as the third contact position. The second pin 32B is an example of the second part of the correction jig. Thereafter, the detection tool 31 is moved away from the second pin 32B.

[0042] Next, the process proceeds to step S15, where the clamp 50 is rotated 180 degrees around the A axis (rotation process). Subsequently, the process proceeds to step S16, where the detection tool 31 is moved in the X-axis direction to bring the detection tool 31 into contact with the first pin 32A (second contact process; see arrow B2 in FIG. 17). The position P12 (x12, y12) at this time is detected as the second contact position. Thereafter, the detection tool 31 is moved away from the first pin 32A.

[0043] Next, the process proceeds to step S17, where the clamp 50 is moved by 2L in the Y-axis direction (second movement process). This positions the detection tool 31 to the side of the second pin 32B. After that, the process proceeds to step S18, where the detection tool 31 is moved in the X-axis direction to contact the second pin 32B (fourth contact process; see arrow B4 in FIG. 17). The position P22 (x22, y22) at this time is detected as the fourth contact position.

[0044] Then, the process proceeds to step S19, where correction processing is performed. In this embodiment, similar to the first embodiment, the tilt angle θA of the Y-axis with respect to the perpendicular to the A-axis is calculated based on contact between the detection tool 31 and the first pin 32A. The tilt angle θA is calculated based on the first contact position P11, the second contact position P12, and the movement distance 2L in the first movement processing. Also, similar to the first embodiment, the tilt angle θB of the Y-axis with respect to the perpendicular to the A-axis is calculated based on contact between the detection tool 31 and the second pin 32B. The tilt angle θB is calculated based on the third contact position P21, the fourth contact position P22, and the movement distance 2L in the second movement processing. Then, the tilt angle θ is calculated by averaging the tilt angle θA calculated based on contact with the first pin 32A and the tilt angle θB calculated based on contact with the second pin 32B. That is, θ = (θA + θB) / 2. In this embodiment, the position coordinates are corrected based on the tilt of the Y axis calculated in this manner.

[0045] In the above method, the movement distances in the first movement process (step S13) and the second movement process (step S17) are set to predetermined distances -2L and 2L, respectively. However, the movement distances may be detected based on contact between the detection tool 31 and the first pin 32A and the second pin 32B in the Y-axis direction. Note that the method for detecting the movement distance based on contact with the pins in the Y-axis direction is the same as the method described above, and therefore its description will be omitted here.

[0046] 18 , the correction device 60 according to this embodiment has processing units that perform the above-described processes. That is, the correction device 60 has a first contact processing unit 61 that performs the first contact processing, a second contact processing unit 62 that performs the second contact processing, a third contact processing unit 61A that performs the third contact processing, a fourth contact processing unit 62A that performs the fourth contact processing, a first movement processing unit 64A that performs the first movement processing, a second movement processing unit 64B that performs the second movement processing, a rotation processing unit 63 that performs the rotation processing, and a correction processing unit 65 that performs the correction processing.

[0047] In this embodiment as well, when performing cutting, the workpiece 5 is attached to the clamp 50, and the machining tool 6 is attached to the spindle 30. The control device 90 controls the positions of the machining tool 6 and the clamp 50 based on the corrected coordinates. This allows for accurate cutting even when the Y-axis is tilted.

[0048] As described above, according to this embodiment, when detecting the tilt of the Y-axis, the detection tool is brought into contact with multiple locations on the correction jig. The tilt of the Y-axis is calculated for each contact with each location, and the average value of these tilts is set as the tilt of the Y-axis. Therefore, according to this embodiment, the position coordinates can be corrected with higher precision. Therefore, cutting can be performed with higher precision.

[0049] In this embodiment, a first pin 32A and a second pin 32B are used as the correction jig. Similar to the pin 32 according to the first embodiment, the tips of the first pin 32A and the second pin 32B have curved surfaces that are curved along the Y-axis direction. This reduces errors caused by the tilt of the first pin 32A and the second pin 32B, enabling the tilt of the Y-axis to be detected with high accuracy.

[0050] While the first and second embodiments of the cutting machine and coordinate correction method have been described above, these are merely examples, and various other embodiments are possible. Next, examples of other embodiments will be briefly described.

[0051] In the first embodiment, in order to bring the detection tool 31 into contact with the same pin 32 in the first contact process and the second contact process, a rotation process is performed in which the clamp 50 is rotated 180 degrees around the A axis, and a movement process is performed in which the clamp 50 is moved in the Y axis direction. That is, in order to bring the detection tool into contact with the same portion (first portion) of the correction jig, both the rotation process and the movement process are performed. However, the detection tool may be brought into contact with different portions of the correction jig in the first contact process and the second contact process. In this case, it is possible to omit either the rotation process or the movement process.

[0052] In the second embodiment, the first pin 32A and the second pin 32B are separate from each other, but they may be integrated. That is, the correction jig may be composed of multiple items or a single item. The shape of the correction jig does not have to be pin-shaped. For example, as shown in FIG. 19 , a rectangular parallelepiped correction jig 32C may be used. Furthermore, as shown in FIG. 20 , a rectangular parallelepiped correction jig 32D having a curved surface curved at least along the Y-axis direction may be used.

[0053] In each of the above embodiments, the spindle 30 moves linearly in the X-axis and Z-axis directions, and the clamp 50 moves linearly in the Y-axis direction and rotates around the A-axis. However, the cutting machine 10 only needs to be able to move the spindle 30 linearly in the X-axis, Y-axis, and Z-axis directions relative to the clamp 50 and rotate around the A-axis. For example, the cutting machine 10 may be configured so that the spindle 30 moves linearly in the X-axis, Y-axis, and Z-axis directions, and the clamp 50 rotates around the A-axis.

[0054] Although the cutting machine 10 according to the embodiment is a dental cutting machine, the use of the cutting machine is not limited to dental applications.

[0055] 5 Workpiece 6 Processing tool 10 Cutting machine 25 Drive device 30 Spindle (second holding member) 31 Detection tool 32 Pin (correction jig) 32A First pin (correction jig) 32B Second pin (correction jig) 50 Clamp (first holding member) 60 Correction device 90 Control device

Claims

1. A method for correcting position coordinates of a cutting machine equipped with a first holding member that holds a workpiece; a second holding member that holds a processing tool that cuts the workpiece; and a drive device that drives at least one of the first holding member and the second holding member to move the processing tool relatively to the workpiece in mutually perpendicular X-axis, Y-axis, and Z-axis directions and rotate the workpiece relatively to the processing tool around an A-axis that is parallel to the X-axis, the method comprising: an attachment process that attaches a correction jig to the first holding member and attaches a detection tool that detects contact with the correction jig to the second holding member; a first contact process that moves the second holding member relatively to the first holding member in the X-axis direction, thereby bringing the detection tool held by the second holding member into contact with the correction jig held by the first holding member, and acquiring a first contact position; and a first movement process that moves the second holding member a first distance relatively to the first holding member in the Y-axis direction. a second contact process of acquiring a second contact position by moving the second holding member relatively to the first holding member in the X-axis direction after the first movement process, thereby bringing the detection tool held by the second holding member into contact with the correction jig held by the first holding member; and a correction process of correcting position coordinates based on at least the first contact position, the second contact position, and the first distance so that the Y-axis is perpendicular to the A-axis when viewed from the Z-axis.

2. A coordinate correction method for a cutting machine as described in claim 1, wherein the first contact process includes a process of acquiring the first contact position by bringing the detection tool into contact with a first portion of the correction jig; after the first contact process and before the second contact process, a rotation process is performed to rotate the first holding member to which the correction jig is attached 180 degrees around the A axis relative to the second holding member; and the second contact process includes a process of acquiring the second contact position by bringing the detection tool into contact with the first portion of the correction jig.

3. The coordinate correction method for a cutting machine according to claim 2, wherein the first portion of the correction jig has a curved surface that is curved at least along the Y-axis direction.

4. A coordinate correction method for a cutting machine according to claim 2, further comprising: a third contact process for acquiring a third contact position by bringing the detection tool held by the second holding member into contact with a second portion of the correction jig held by the first holding member; a second movement process for moving the second holding member a second distance in the Y-axis direction relative to the first holding member; and a fourth contact process for acquiring a fourth contact position by bringing the detection tool into contact with the second portion of the correction jig after the second movement process, wherein the correction process comprises: a process for calculating a first tilt angle of the Y-axis with respect to a perpendicular line to the A-axis as viewed from the Z-axis, based on the first contact position, the second contact position, and the first distance; a process for calculating a second tilt angle of the Y-axis with respect to a perpendicular line to the A-axis as viewed from the Z-axis, based on the third contact position, the fourth contact position, and the second distance; and a process for correcting position coordinates so that the Y-axis is perpendicular to the A-axis as viewed from the Z-axis, based on the first tilt angle and the second tilt angle.

5. A coordinate correction method for a cutting machine according to claim 4, wherein the first and second parts of the correction jig have curved surfaces that are curved at least along the Y-axis direction.

6. A system comprising: a first holding member for holding a workpiece; a second holding member for holding a processing tool for cutting the workpiece; a drive device for driving at least one of the first holding member and the second holding member to move the processing tool relatively to the workpiece in the mutually orthogonal X-axis, Y-axis, and Z-axis directions and to rotate the workpiece relatively to the processing tool around an A-axis parallel to the X-axis; a correction jig held by the first holding member; a detection tool held by the second holding member; and a correction device for correcting position coordinates, wherein the correction device comprises: a first contact processing unit for performing first contact processing to bring the detection tool held by the second holding member into contact with the correction jig held by the first holding member by moving the second holding member relatively to the first holding member in the X-axis direction, thereby obtaining a first contact position; and a movement processing unit for performing movement processing to move the second holding member a first distance relatively to the first holding member in the Y-axis direction. a second contact processing unit that performs a second contact processing to acquire a second contact position by moving the second holding member relatively to the first holding member in the X-axis direction after the movement processing, thereby bringing the detection tool held by the second holding member into contact with the correction jig held by the first holding member; and a correction processing unit that corrects position coordinates based on at least the first contact position, the second contact position, and the first distance so that the Y-axis is perpendicular to the A-axis when viewed from the Z-axis.

7. A cutting machine as described in claim 6, wherein the first contact processing unit is configured to acquire the first contact position by bringing the detection tool into contact with a first portion of the correction jig, the correction device has a rotation processing unit that executes a rotation processing to rotate the first holding member to which the correction jig is attached 180 degrees around the A axis relative to the second holding member after the first contact processing and before the second contact processing, and the second contact processing unit is configured to acquire the second contact position by bringing the detection tool into contact with the first portion of the correction jig.

8. The cutting machine according to claim 6, wherein the first portion of the correction jig has a curved surface that is curved at least along the Y-axis direction.

9. The correction device further includes a third contact processing unit that performs a third contact processing to acquire a third contact position by bringing the detection tool held by the second holding member into contact with a second portion of the correction jig held by the first holding member; a second movement processing unit that performs a second movement processing to move the second holding member a second distance in the Y-axis direction relative to the first holding member; and a fourth contact processing unit that performs a fourth contact processing to acquire a fourth contact position by bringing the detection tool into contact with the second portion of the correction jig after the second movement processing, wherein the correction processing unit performs: a process of calculating a first tilt angle of the Y-axis with respect to a perpendicular line to the A-axis as viewed from the Z-axis, based on the first contact position, the second contact position, and the first distance; and a process of calculating a second tilt angle of the Y-axis with respect to a perpendicular line to the A-axis as viewed from the Z-axis, based on the third contact position, the fourth contact position, and the second distance. and correcting position coordinates based on the first tilt angle and the second tilt angle so that the Y-axis is perpendicular to the A-axis when viewed from the Z-axis.

10. The cutting machine according to claim 9, wherein the first and second parts of the correction jig have curved surfaces that are curved at least along the Y-axis direction.

Images