Calibration device, calibration method, and machine tool

Abstract

The correction device (10) is provided with: a shaft part (14) that can extend from the correction device (10) in the axial direction; an outer cylinder section (12) that supports the shaft section (14) therein; a coil spring (24) which is disposed inside the outer cylinder section (12) and which biases the shaft section (14) in the extension direction; temporary stop mechanisms (12a, 12b, 15) that stop the shaft section (14) at the press-fit position against the biasing force of the coil spring (24); a fixing part (16) which is arranged on the outer cylinder part (12) and can fix the shaft part (14) to the outer cylinder part (12); an XY correction section (26) formed along the outer peripheral surface of the shaft section (14); and a Z correction section (28) formed at the tip of the shaft section (14) and having a plane orthogonal to the axial direction of the shaft section (14).

Description

Technical Field

[0001] This invention relates to a calibration device, a calibration method, and a machine tool. Background Technology

[0002] For machine tools to perform high-precision machining, they require the positional information, or coordinates, of the workpiece. After the operator mounts the workpiece onto the machine tool at the machining site, positional information is obtained either manually or using a measuring device equipped with sensors mounted on the machine tool. This measuring device is a sensor-based system; therefore, gauges or similar references are needed to verify measurement errors and correct the measurement results. This correction process is also known as calibration, and the accuracy of the measurement results is highly correlated with the accuracy of the calibration.

[0003] Patent Document 1 discloses a calibration device for machine tools, which includes a base that can be mounted on the machine tool and a spherical calibration standard. However, the origin of the coordinates in the vertical direction (i.e., the Z-axis direction) needs to be manually obtained using a reference tool and a gauge block. Specifically, the measuring operator needs to manually lower the tool until the gauge block is clamped between the reference tool and the ball, making the calibration operation cumbersome even when using a calibration device. Furthermore, the calibration operations for the horizontal direction (i.e., the X-axis and Y-axis directions) and the Z-axis direction coordinates need to be performed separately. Therefore, the calibration operation time and number of steps increase. Moreover, the manual calibration operation requires skill, and the measurement accuracy can fluctuate due to differences in the measuring operator's skill level, making it difficult to teach others the skills associated with such cumbersome operations.

[0004] Therefore, for example, Patent Document 2 discloses a calibration device for a coordinate positioning machine tool, which is equipped with a base, a calibration standard, and a locking mechanism for mounting the calibration standard to the base. Here, the locking mechanism of the calibration device can be in a unlocked state where the calibration standard can be moved relative to the base by using external force; and in a locked state where the position of the calibration standard is locked relative to the base. However, when a rod (a reference tool of known length) held on the spindle of the machine tool is brought into contact with the calibration standard (calibration ball) for positioning, there is a possibility of misoperation causing the rod to move excessively towards the calibration ball. In this case, not only will the calibration device be damaged, but there is also a possibility of applying a very large load to the spindle and the machine tool via the rod.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Publication No. 2019-509902

[0008] Patent Document 2: Japanese Patent Publication No. 2023-519290 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] In view of the above, the present invention aims to provide a calibration device, calibration method, and machine tool using the device and method that are highly safe and easy to operate, which can prevent the reference tool from being excessively pressed into the calibration device during the calibration operation, and suppress the decrease in work efficiency caused by excessive caution in the calibration operation due to concerns about excessive pressing.

[0011] Methods for solving problems

[0012] According to one embodiment of the present invention, a calibration device for a probe used in a machine tool is provided, comprising: a shaft portion formed in the shape of a rod, capable of extending axially from the calibration device; an outer cylinder portion supporting the shaft portion on its inner side; a force-applying portion disposed inside the outer cylinder portion, applying force to the shaft portion in the extending direction; a temporary stop mechanism overcoming the force of the force-applying portion and stopping the shaft portion in a pressed-in position; a fixing portion disposed in the outer cylinder portion, capable of fixing the shaft portion relative to the outer cylinder portion; an XY calibration portion formed along the outer peripheral surface of the shaft portion or the outer cylinder portion; and a Z calibration portion formed at the top end of the shaft portion, having a plane orthogonal to the axial direction of the shaft portion.

[0013] Furthermore, according to one embodiment of the present invention, a machine tool capable of mounting a calibration device according to one embodiment of the present invention is provided, comprising: a spindle for mounting a machining tool, and a reference tool and a probe for mounting a reference tool instead of the machining tool; a worktable for mounting a workpiece and the calibration device; and a feed axis for moving the spindle relative to the worktable.

[0014] Furthermore, according to one embodiment of the present invention, a calibration method for a probe employing a calibration device according to an embodiment of the present invention is provided, comprising: arranging the calibration device on a machine tool; stopping the shaft portion in a press-in position using a temporary stop mechanism; mounting a reference tool on the spindle of the machine tool, causing the spindle to move relative to the shaft portion so that the tip of the reference tool is positioned axially above the Z-calibration portion of the shaft portion; releasing the temporary stop mechanism, and applying force to the shaft portion towards the reference tool using a force-applying part; fixing the shaft portion abutting against the reference tool using a fixing part; obtaining a reference coordinate in the axial direction of the fixed shaft portion; mounting the probe on the spindle of the machine tool; obtaining a reference coordinate in the direction orthogonal to the axial direction of the shaft portion; and obtaining calibration values ​​in the axial direction and in the direction orthogonal to the axial direction based on the reference coordinates.

[0015] The effects of the invention

[0016] According to one embodiment of the present invention, a calibration device includes: a shaft portion that extends axially from the calibration device; a force-applying portion that applies force to the shaft portion in the extension direction; a temporary stop mechanism that overcomes the force of the force-applying portion and stops the shaft portion in a pressed-in position; and a fixing portion that fixes the shaft portion relative to an outer cylinder portion. Therefore, since the force-applying portion can apply force to the shaft portion and fix it in the extended position, axial positioning of the shaft portion can be performed easily and quickly. Furthermore, the temporary stop mechanism can be used to temporarily stop the shaft portion in the pressed-in position. Therefore, to set the position of the fixed shaft portion, it is only necessary to move the tip of a reference tool mounted on the spindle of a machine tool to the vicinity of the shaft portion of the calibration device, and by releasing the temporary stop and bringing the shaft portion subjected to force by the force-applying portion into contact with the tip of the reference tool mounted on the spindle of the machine tool, the position can be set. Therefore, the machine tool is prevented from being overloaded due to collision between the tip of the reference tool and the shaft. Furthermore, the delicate operation of pressing the reference tool into the shaft by a specified amount is eliminated, thus suppressing a decrease in work efficiency and ensuring machine tool safety. The alignment device further includes an XY alignment section formed along the outer circumferential surface of the shaft and a Z alignment section formed at the tip of the shaft, having a plane orthogonal to the shaft's axial direction. Therefore, alignment along the shaft and in the direction orthogonal to the shaft can be easily performed using only one shaft (i.e., the alignment device). Thus, alignment operations can be performed easily and efficiently without relying on the operator's skill level, and such operations can be performed periodically without trouble, thereby ensuring stable quality (i.e., machining accuracy) of the machined products.

[0017] According to one embodiment of the present invention, a machine tool can be equipped with a calibration device according to one embodiment of the present invention, and a reference tool and a probe can be mounted on the spindle. Therefore, calibration operations can be performed easily and in a short time. Furthermore, it is possible to prevent or suppress the tip of the reference tool mounted on the spindle of the machine tool from colliding with the spindle and applying load to the machine tool, thereby ensuring the safety of the machine tool.

[0018] According to one embodiment of the present invention, the calibration method enables continuous alignment along the shaft direction and in directions orthogonal to the shaft using a single calibration device. This allows for simple and quick calibration operations. Furthermore, it prevents or suppresses the tip of a reference tool mounted on the machine tool spindle from colliding with the shaft and applying load to the machine tool, thus ensuring machine tool safety. Attached Figure Description

[0019] Figure 1 A perspective view showing the correction device according to the first embodiment.

[0020] Figure 2 A perspective view showing the state in which the shaft of the correction device is extended.

[0021] Figure 3A shows along Figure 1 Figure 3A shows a cross-sectional view of the correction device with the shaft in the raised state, taken along line 3-3; Figure 3B shows a cross-sectional view of the correction device of Figure 3A taken along line 3B-3B.

[0022] Figure 3C shows along Figure 1 The 3-3 line shows a cross-sectional view of the correction device in which the shaft is temporarily stopped in the press-in position; Figure 3D shows a cross-sectional view of the correction device of Figure 3C along the 3D-3D line.

[0023] Figure 3E shows along Figure 1 The 3-3 line shows a cross-sectional view of the correction device in the state where the temporary stop is lifted and the shaft is in contact with the tip of the reference tool; Figure 3F shows a cross-sectional view of the correction device of Figure 3E along the 3F-3F line.

[0024] Figure 3G indicates along Figure 1 The 3-3 line shows a sectional view of the correction device with the shaft fixed; Figure 3H shows a sectional view of the correction device of Figure 3G taken along the 3H-3H line.

[0025] Figure 4A A perspective view showing the correction device with the cover removed.

[0026] Figure 4B Indicates along Figure 1 The 4-4 line is a sectional view of the correction device that puts the cam rod in the loose state.

[0027] Figure 4C Indicates along Figure 1 The 4-4 line is a sectional view of the correction device that puts the cam rod in a clamped state.

[0028] Figure 5A shows a side view of the calibration device; Figure 5B shows a bottom view of the calibration device in Figure 5A.

[0029] Figure 5C shows a side view of the calibration device when it is installed on the worktable; Figure 5D shows a side view of the calibration device when it is removed from the worktable.

[0030] Figure 6 A flowchart illustrating the probe calibration process.

[0031] Figure 7 A side view showing a machine tool equipped with reference tools and calibration devices.

[0032] Figure 8This is a top view of the Z-correction section used to represent the relationship between the temporary reference coordinates and the reference coordinates.

[0033] Figure 9 A three-dimensional diagram illustrating the calibration method for the probe.

[0034] Figure 10 This is a top view illustrating the method for obtaining the reference coordinates in the X and Y directions.

[0035] Figure 11A-11B This is a diagram schematically showing the state in which the shaft is clamped by the temporary stop mechanism according to the second embodiment from both top and side views. It is a cross-sectional view taken along lines 11A-11A and 11B-11B respectively.

[0036] Figure 11C-11D This is a top and side view schematically showing the state in which the shaft is released from clamping by the temporary stop mechanism according to the second embodiment. It is a cross-sectional view cut along lines 11C-11C and 11D-11D respectively.

[0037] Figure 12 A side view showing a variant of the reference tool. Detailed Implementation

[0038] The calibration apparatus, machine tool, and calibration method according to the embodiments will now be described with reference to the accompanying drawings. The same or corresponding elements are labeled with the same reference numerals, and repeated descriptions are omitted. For ease of understanding, the scale of the drawings may be changed for illustration purposes.

[0039] (First Implementation)

[0040] The first embodiment of the present invention will now be described with reference to the accompanying drawings. Figure 1 and Figure 2 The image shows a perspective view of the calibration device 10. (See image below.) Figure 7 and Figure 9 As shown, the calibration device 10 is used to calibrate the position of the probe 60 in the machine tool 50, for example, to accurately determine the position of a workpiece (not shown). For this purpose, the calibration device 10 is mounted on the worktable 52 of the machine tool 50, which is used to mount the workpiece (not shown) to be processed. In the accompanying drawings, arrows indicate the forward / backward, left / right, and up / down directions of the device when the machine tool 50 is positioned on a horizontal surface such as the ground in a factory. In the figures, X represents the left / right direction (X-axis direction), Y represents the forward / backward direction (Y-axis direction), and Z represents the up / down direction (Z-axis direction).

[0041] like Figure 1 and Figure 2 As shown, the calibration device 10 includes an outer cylinder portion 12, a shaft portion 14, and a fixing portion 16 (see reference). Figure 4A For the calibration device 10, the outer cylinder portion 12 is positioned on the worktable 52 of the machine tool 50 (see reference). Figure 7 The upper surface of the outer cylinder 12 is such that a metal shaft 14, which is formed in the shape of a rod, extends toward the upper side of the outer cylinder 12. At this time, a fixing part 16 is formed to fix the position of the extended shaft 14.

[0042] like Figure 1 As shown in Figure 3A, the outer cylinder 12 is made of metal and has a cylindrical outer periphery. A thin-walled cylindrical portion 18, used for fastening the shaft portion 14, is integrally formed with the outer cylinder 12 at its upper center. A hole 20 is formed at the center of the thin-walled cylindrical portion 18 and the outer cylinder 12, extending along the axial direction (i.e., the Z-axis direction) of the shaft portion 14 housed within the outer cylinder 12 and the thin-walled cylindrical portion 18. The inner diameter of the hole 20 at the upper portion of the thin-walled cylindrical portion 18 and the outer cylinder 12 is formed to be substantially the same as the outer diameter of the shaft portion 14, so that the shaft portion 14 can be housed and fastened.

[0043] As shown in Figure 3A, a circular plate-shaped magnet 22 is disposed on the bottom side of the outer cylinder 12 to block the hole 20. Therefore, it is possible to block the hole 20 on the metal worktable 52 (see Figure 3A). Figure 7 The position of the calibration device 10 is stable and does not shift. A helical spring 24, serving as a force-applying component, is disposed between the lower end of the shaft 14 housed in the hole 20 and the magnet 22. Therefore, it is possible to apply force to the shaft 14 housed in the hole 20 on the upward side, i.e., the reference tool 58 and the probe 60 side (see reference 20). Figure 7 and Figure 9 Applying force. This allows the shaft portion 14 to come into contact with the tip of the reference tool 58 disposed on the upper side of the shaft portion 14. Furthermore, the tip of the reference tool 58 is preferably spherical.

[0044] An XY correction portion 26 is formed on the upper side of the shaft portion 14 that is housed in the hole portion 20. The outer periphery of the XY correction portion 26 is cylindrical. The XY correction portion 26 extends radially toward the shaft portion 14 compared to the other parts of the shaft portion 14, and its central axis is formed to coincide with the central axis of the shaft portion 14.

[0045] At the top of the shaft portion 14, a Z-correction portion 28 is formed. This Z-correction portion 28 has a plane orthogonal to the axial direction of the shaft portion 14, that is, parallel to the mounting surface AS (see Figure 5C) of the mounting correction device 10 of the worktable 52. Here, even when the reference tool 58 is in contact with the worktable 52 at any position in the X-axis or Y-axis direction, the correct Z-axis position of the XY correction portion 26 at its center axis position can be obtained by measuring the relative difference between the Z-axis position at the X-axis or Y-axis position where the reference tool 58 is in contact and the Z-axis position at the center axis position of the XY correction portion 26 on the plane of the Z-correction portion 28. Therefore, positioning in the X-axis and Y-axis directions when the reference tool 58 is in contact can be performed easily and quickly.

[0046] As shown in Figures 3A and 3B, a retaining ring 15 is installed at the lower end of the shaft portion 14. The retaining ring 15 is formed in an annular shape along the outer periphery of the shaft portion 14, constituting a temporary stopping mechanism. The retaining ring 15 has a hook portion 15a extending radially outward from a portion of its outer periphery, i.e., radially outward from the shaft portion 14. In addition, a first stepped portion 12a and a second stepped portion 12b constituting the temporary stopping mechanism are formed in a stepped manner on the lower side of the hole portion 20 of the outer cylinder portion 12. Specifically, the first stepped portion 12a is formed concentrically with the hole portion 20 and has an inner diameter larger than the inner diameter of the hole portion 20. In addition, the second stepped portion 12b is formed concentrically with the hole portion 20 and the first stepped portion 12a on the lower side of the first stepped portion 12a and has an inner diameter larger than the inner diameter of the first stepped portion 12a. Furthermore, a portion of the second stepped portion 12b is cut out so that the hook portion 15a can pass through when the shaft portion 14, on which the retaining ring 15 is mounted, moves up and down. Since the retaining ring 15 abuts against the upper end of the first stepped portion 12a that communicates with the upper side of the hole portion 20, the shaft portion 14 is restricted from moving upward in this position.

[0047] Furthermore, as shown in Figures 3C and 3D, when the force of the coil spring 24, i.e., the spring force, is overcome and the shaft 14 is pressed downwards to the second step 12b, and the shaft 14 is rotated until the hook portion 15a and the cut portion of the second step 12b do not overlap in a top view, the hook portion 15a of the retaining ring 15 abuts against the second step 12b, restricting the upward movement of the shaft 14 at this position. Therefore, the shaft 14 can be stopped and temporarily held at this position. Here, the hook portion 15a rotates 90 degrees from the cut portion of the second step 12b.

[0048] Additionally, as shown in Figures 3E and 3F, when the reference tool 58 (refer to...) Figure 7With the top end of the shaft 14 moved at a predetermined interval above the temporarily stopped shaft 14, the shaft 14 is rotated so that the hook 15a passes through the cut of the second step 12b. The shaft 14 then rises due to the spring force of the coil spring 24. Therefore, by moving the shaft 14, the Z-correction part 28 can come into contact with the top end of the reference tool 58.

[0049] Furthermore, as shown in Figures 3G and 3H, with the Z-correction part 28 abutting against the top end of the reference tool 58, the cam rod 32 is rotated to clamp the shaft part 14, as described later. This allows the height position of the shaft part 14 in the correction device 10 to be fixed.

[0050] exist Figure 4A The middle section shows a perspective view of the alignment device 10 with the shaft portion 14 and the cover portion 34 removed. The fixing portion 16 formed on the radially outer side of the thin-walled cylindrical portion 18 (see reference). Figure 4A It includes: a metal pressing part 30 serving as a clamp for pressing the thin-walled cylindrical part 18; a metal cam rod 32 for applying pressure to the pressing part 30; a hard resin covering part 34 configured to cover the outside of the pressing part 30; and a contact part 31 for contacting the cam rod 32 (see reference). Figure 4C Additionally, while the cover 34 is described here as being made of rigid resin, it is not limited to this and may also be made of other materials besides rigid resin.

[0051] like Figures 4A to 4C As shown, the pressing part 30 has an inner portion 36, which is formed to surround, i.e., clamp, the outer side of the thin-walled cylindrical part 18, and its inner width is formed to be the same as the outer diameter of the thin-walled cylindrical part 18. Furthermore, one longitudinal end of the pressing part 30 is fastened to the outer cylindrical part 12 by a bolt 29, and a gap 30a extending through to the inner portion 36 is formed at the other longitudinal end. Furthermore, a rod-shaped pin 40 is installed at the other longitudinal end of the pressing part 30, the shaft portion of which passes through the gap 30a and extends into the interior of the pressing part 30. A bushing 38 is installed on the pin 40 exposed from the pressing part 30, and a cam rod 32 is rotatably connected to the end of the pin 40 by a screw 33.

[0052] The cam rod 32 is formed rotatably in the horizontal direction about a central axis extending in the Z-axis direction. Furthermore, the cam rod 32 has a cam portion 32a formed in a cam shape on the central axis side, and a rod portion 32b extending radially (in this case, horizontally) from the cam portion 32a along the central axis. Therefore, when from... Figure 4B When the shaft portion 14 is in the released state, and the rod portion 32b is rotated toward the side that abuts against the contact portion 31, as shown... Figure 4CAs shown, the cam portion 32a pushes the pressing portion 30 via the bushing 38, causing the pressing portion 30 to elastically deform. This closes the gap 30a, and the inner portion 36 pushes the thin-walled cylindrical portion 18 evenly from both sides in the radial direction inward. As a result, the thin-walled cylindrical portion 18 elastically deforms and secures the shaft portion 14. Therefore, the position and orientation of the shaft portion 14 abutting against the reference tool 58 are not disrupted, forming a clamping state that fixes the shaft portion 14 relative to the thin-walled cylindrical portion 18. Furthermore, screws 42 and 44 are installed on the pressing portion 30 at the end of the pressing portion 30 and on the side of the pin 40 for fixing the pin 40. Therefore, when the cam rod 32 is rotated from the loosened state to the clamped state, the pressing portion 30 can be stably pulled to a degree equivalent to the lift of the cam portion 32a, and the thin-walled cylindrical portion 18 and the shaft portion 14 can be stably clamped.

[0053] Additionally, when in Figure 4C In the clamped state shown, the rod 32b is rotated toward the side separated from the contact portion 31, forming... Figure 4B In the released state shown, the bushing 38, the pressing part 30, and the thin-walled cylindrical part 18 are no longer pushed by the cam part 32a. Therefore, the thin-walled cylindrical part 18 releases the shaft part 14, and the shaft part 14 can extend upward by means of the spring force of the coil spring 24.

[0054] Figures 5A and 5B show a side view and a bottom view of the correction device 10. At the bottom of the outer cylinder 12, in a portion radially outward of the magnet 22 located at the center, an inclined surface 12d is formed. This inclined surface 12d is radially inclined upward toward the outer periphery of the outer cylinder 12 relative to the bottom surface. Additionally, bolts 35 are used to fix the cover 34 to the outer cylinder 12.

[0055] In Figures 5C and 5D, it is shown that the worktable 52 (refer to) Figure 7Figure 5C shows a side view of the alignment device 10 during installation and removal from the mounting surface AS. As shown in Figure 5C, when the alignment device 10 is installed on the mounting surface AS, it can be tilted so that the tilted surface 12d abuts against the mounting surface AS. From this position, the alignment device 10 is tilted in the direction of the arrow in the figure, using the tilted surface 12d as a fulcrum, so that the bottom surface of the outer cylinder 12 abuts against the mounting surface AS. Furthermore, as shown in Figure 5D, when removing the alignment device 10 from the mounting surface AS, it can be tilted in the direction of the arrow in the figure, and the tilted surface 12d abuts against the mounting surface AS, thereby disengaging the magnet 22 from the mounting surface AS. The alignment device 10 can be removed from the mounting surface AS without direct contact between the magnet 22 and the mounting surface AS. Therefore, it is possible to prevent or suppress the alignment device 10 from violently abutting against the mounting surface AS due to the magnetic force of the magnet 22, i.e., from colliding. Furthermore, since it is not necessary to pull the calibration device 10 along the direction of magnetic force, i.e., the up-down direction, the calibration device 10 can be easily and conveniently removed from the mounting surface AS. This prevents or suppresses damage to the mounting surface AS during the installation and removal of the calibration device 10. In addition, since the conventional magnetic frame method with a magnetic switch lever is not used, the installation and removal of the calibration device 10 relative to the worktable 52 can be performed quickly.

[0056] By means of Figure 6 The following is an explanation of the correction method described in the flowchart shown. The effects of the correction device 10, correction method, and machine tool 50 according to this embodiment will be explained below.

[0057] First, proceed to step S10, as follows: Figure 7 As shown, the calibration device 10 is mounted on the worktable 52 of the machine tool 50, which is used to calibrate the probe 60 for measuring the workpiece. Here, the calibration device 10 is configured such that the upper surface (plane) of the Z-calibration section 28 is parallel to the lower end face of the spindle 54 of the machine tool 50 for mounting tools, that is, the plane of the Z-calibration section 28 is horizontal.

[0058] Next, proceeding to step S20, as shown in Figures 3C and 3D, the shaft 14 is pushed towards the outer cylinder 12 and rotated, thereby temporarily stopping the shaft 14. Then, proceeding to step S30, the reference tool 58, mounted on the tool holder 56 of known length LT, is assembled onto the spindle 54, and proceeding to step S40, the reference tool 58 is positioned. Positioning is performed using a feed axis device (not shown) on the machine tool 50, which moves the spindle 54 along the X-axis, Y-axis, and Z-axis directions, so that the top end (in this case, the lower end) of the reference tool 58 is positioned at a predetermined distance from the upper side of the Z-correction section 28 of the shaft 14. This predetermined distance is only required to be within the range of the stroke between the temporary stop position and the rising position of the shaft 14; for example, if the stroke is 7 mm, approximately 4 mm can be selected. Since there is no need to perform the operation of bringing the reference tool 58 into contact with and pushing the shaft 14, collisions can be prevented.

[0059] If the reference tool 58 is positioned, proceed to step S50, as shown in Figures 3E and 3F, rotate the shaft 14 to release the temporary stop, and apply upward force to the shaft 14 using spring force. Thus, as... Figure 7 As shown, the Z-correction part 28 can be brought into contact with the lower end of the reference tool 58. If the Z-correction part 28 is in contact, step S60 is entered. As shown in Figures 3G and 3H, with the Z-correction part 28 in contact with the reference tool 58, the cam rod 32 is rotated toward the contact part 31 to fix the shaft part 14.

[0060] like Figure 8 As shown, the position where the top of the reference tool 58 abuts against the plane of the Z-correction unit 28 is obtained (step S70) and used as the reference Z-coordinate Zm in the Z-axis direction. Furthermore, the positions of the reference Z-coordinate Zm in the X-axis and Y-axis directions may not necessarily be the center of the Z-correction unit 28, i.e., the reference coordinates (Xm, Ym). Therefore, the position where the top of the reference tool 58 abuts against the plane of the Z-correction unit 28 is measured and used as the temporary reference coordinates (Xm1, Ym1) in the X-axis and Y-axis directions.

[0061] If a baseline Z-coordinate Zm and a temporary baseline coordinate (Xm1, Ym1) are set, proceed to step S80, replacing the baseline tool 58, and... Figure 7The probe 60 shown is mounted on the spindle 54. Next, in step S90, the probe 62, positioned at the tip of the probe 60, is positioned at temporary reference coordinates (Xm1, Ym1). Then, in step S100, the X-axis, Y-axis, and Z-axis positions are corrected using the probe 60 mounted on the spindle 54. Furthermore, the tip of the reference tool 58 can be various shapes, such as flat, pointed, spherical, or even a cutting tool. Microscopically, the plane of the Z-correction section 28 at the tip of the shaft 14 cannot be guaranteed to be perpendicular to the axis of the spindle 54 of the machine tool 50, nor can absolute flatness be guaranteed. Therefore, the tip of the reference tool 58 that abuts against the Z-correction section 28 is typically chosen to be a point-contact spherical shape. However, strictly speaking, the contact position between the reference tool 58 and the probe 62 relative to the Z-correction section 28 at the temporary reference coordinates (Xm1, Ym1) is considered to have an extremely small difference. In order to perform high-precision measurements that minimize the difference, it is preferable to form the tip of the reference tool 58 into a spherical shape with a radius R that is the same size as the radius R of the ball part of the probe 62.

[0062] The correction of the X-axis, Y-axis, and Z-axis positions in steps S90 and S100 will be explained in detail below. First, the reference coordinates (Xm, Ym) in the X-axis and Y-axis directions are acquired. Furthermore, the probe 60 can emit a signal when it comes into contact with the object being measured. The machine tool is equipped with a control device and a signal receiving device that can detect the contact between the probe 60 and the object being measured. Additionally, during the measurement in acquiring the reference coordinates (Xm, Ym), the probe 62 of the probe 60 is controlled to always face the same phase relative to the direction of movement. Figure 10 As shown, the machine tool 50 moves the spindle 54 relative to each other using the feed axis device, causing the probe 62 of the probe 60, located at the temporary reference coordinates (Xm1, Ym1), to move along path C3 (refer to...). Figure 9 The probe 62 is moved in the positive X-axis direction (X-axis + direction). At position C3P where the moved probe 62 contacts the XY correction unit 26, the X-coordinate is measured. Additionally, the probe 62 of the probe 60 is moved along path C4 (refer to...). Figure 9 The probe 62 moves in the negative X-axis direction (X-axis direction). At position C4P where the moved probe 62 contacts the XY correction unit 26, the X coordinate is measured. Here, since the Y coordinates of positions C3P and C4P are constant at Ym1, the machine tool 50 can calculate the average value of these X coordinates as the first X coordinate at the midpoint between positions C3P and C4P.

[0063] Furthermore, the machine tool 50 uses the feed axis device to move the spindle 54 relative to the probe 60, which uses the X coordinate as the first X coordinate, along path C5 (refer to...). Figure 9The probe 62 is moved in the positive Y-axis direction (Y-axis + direction). The Y-coordinate is measured at the position where the moved probe 62 contacts the XY correction unit 26. Additionally, the probe 62 of the probe 60 is moved along path C6 (refer to...). Figure 9 The probe 62 moves in the negative Y-axis direction (Y-axis direction). The Y-coordinate is measured at the position where the moved probe 62 contacts the XY correction unit 26. Since the X-coordinates of the two locations are constant at the first X-coordinate, the machine tool 50 can calculate the average of these Y-coordinates as the Y-coordinate at the intermediate position, i.e., the reference coordinate Ym.

[0064] Furthermore, the machine tool 50 uses the feed axis device to move the spindle 54 relative to the probe, and moves the probe 62 of the probe head 60, with the Y-coordinate as the reference coordinate Ym, along path C3 in the X-axis + direction. The X-coordinate is measured at the position where the moved probe 62 contacts the XY correction unit 26. Additionally, the probe 62 of the probe head 60 is moved along path C4 in the X-axis - direction. The X-coordinate is measured at the position where the moved probe 62 contacts the XY correction unit 26. Here, since the Y-coordinates of the two locations are constant at Ym, the machine tool 50 can calculate the average of these X-coordinates as the X-coordinate at the intermediate position, i.e., the reference coordinate Xm. Thus, the probe 62 of the probe head 60 is positioned at the reference coordinates (Xm, Ym).

[0065] like Figure 9 As shown, the probe 62 of the probe head 60, positioned at reference coordinates (Xm, Ym), is used to perform calibration measurements in the X-axis and Y-axis directions. First, the probe 62 of the probe head 60 is positioned in the X-axis+ direction, i.e., moved along path C3. At the point where the moved probe 62 contacts the XY calibration unit 26, a calibration measurement in the X-axis+ direction is performed to obtain the calibration values ​​(X and Y coordinates) in the X-axis+ direction. Next, the probe 62 of the probe head 60 is positioned in the X-axis negative direction (X-axis-direction), i.e., moved along path C4. At the point where the moved probe 62 contacts the XY calibration unit 26, a calibration measurement in the X-axis-direction is performed to obtain the calibration values ​​(X and Y coordinates) in the X-axis-direction.

[0066] Next, the probe 62 of the probe head 60 is positioned in the Y-axis + direction, that is, moved along path C5. A correction measurement in the Y-axis + direction is performed at the point where the moved probe 62 contacts the XY correction unit 26, obtaining the correction value (X coordinate and Y coordinate) in the Y-axis + direction. Additionally, the probe 62 of the probe head 60 is positioned in the Y-axis - direction, that is, moved along path C6. A correction measurement in the Y-axis - direction is performed at the point where the moved probe 62 contacts the XY correction unit 26, obtaining the correction value (X coordinate and Y coordinate) in the Y-axis - direction. The acquisition of correction values ​​in the X-axis + direction, X-axis - direction, Y-axis + direction, and Y-axis - direction is repeated multiple times, and the average value is stored (i.e., recorded) as the correction value in the machine tool 50.

[0067] Machine tool 50 calculates the eccentricity of probe 62 of probe 60 relative to spindle 54 from the correction values ​​in the X-axis + direction, X-axis - direction, Y-axis + direction, and Y-axis - direction, and positions it from the reference coordinate (Xm, Ym) to the reference coordinate (Xm2, Ym2) taking into account the eccentricity (C7 in the figure). Then, probe 62 of probe 60, positioned at the reference coordinate (Xm2, Ym2) taking into account the eccentricity, is further positioned in the negative Z-axis direction (Z-axis - direction), i.e., moved along path C8. At the position where the moved probe 62 contacts the Z-correction unit 28, a Z-axis - direction correction measurement is performed to obtain the Z-axis - direction correction value (Z coordinate). This operation is repeated multiple times, and the average value is stored in machine tool 50 as the correction value.

[0068] According to the calibration device 10, calibration method, and machine tool 50 of this embodiment, the shaft portion 14, on which the Z-calibration section 28 is formed, can be extended from the outer cylinder portion 12 along the Z-axis direction using the helical spring 24, and the shaft portion 14 can be fixed using the fixing part 16 at the extended position, i.e., at the position where the top end of the reference tool 58 abuts against the Z-calibration section 28. Therefore, the alignment of the reference tool 58 in the Z-axis direction can be performed easily. In addition, in order to perform the calibration operation of the probe 60, it is necessary to obtain the reference coordinates in the X-axis, Y-axis, and Z-axis directions. However, in the conventional method, the following operation needs to be performed manually: the reference tool, whose tool length LT is known, is gradually brought closer in units of several micrometers, while the gauge assembly is moved in and out to confirm contact. Therefore, alignment is very time-consuming, and there is also a risk of collision between the reference tool and the gauge block due to misoperation. However, here, the reference tool 58 only needs to be brought closer to the Z-calibration section 28 to a predetermined position before alignment in the Z-axis direction, and the alignment of the Z-calibration section can be performed with good operability and safety.

[0069] Furthermore, according to the calibration device 10, calibration method, and machine tool 50 of this embodiment, the shaft portion 14 can be temporarily stopped in the pressed-in position using the temporary stop mechanisms 12a, 12b, and 15. Therefore, in order to set the position for fixing the shaft portion 14, the reference tool 58 of the machine tool 50 only needs to be moved to the vicinity of the shaft portion 14 of the calibration device 10. By releasing the temporary stop and bringing the shaft portion 14, which is under the force of the helical spring 24, into contact with the reference tool 58 of the machine tool 50, the position can be set. As a result, it is possible to prevent or suppress the reference tool 58 from excessively pressing into the shaft portion 14 and thus applying a load to the machine tool 50, thereby ensuring the safety of the machine tool 50.

[0070] Furthermore, according to the calibration device 10, calibration method, and machine tool 50 of this embodiment, the calibration device 10 has an XY calibration section 26 formed along the outer peripheral surface of the shaft portion 14, and a Z calibration section 28 formed at the top end of the shaft portion 14 and having a plane orthogonal to the Z-axis direction. Therefore, alignment in the X-axis, Y-axis, and Z-axis directions can be easily performed using only one shaft portion 14, i.e., the calibration device 10. Thus, calibration operations can be performed without relying on the skill level of the operator. Furthermore, since such simple calibration operations can be performed periodically, the quality, i.e., the machining accuracy, of the processed products can be stabilized.

[0071] According to the machine tool 50 of this embodiment, a calibration device 10 can be installed on the machine tool 50, and a reference tool 58 and a probe 60 can be installed on the spindle 54 of the machine tool 50. Therefore, calibration operations can be performed easily, quickly, and with good operability.

[0072] According to the calibration method of this embodiment, alignment along the Z-axis direction of the shaft 14 and along the X-axis and Y-axis directions orthogonal to the axial direction can be performed continuously using a single calibration device 10. Therefore, calibration operations can be performed easily, quickly, and with good operability.

[0073] In summary, the calibration device 10, calibration method, and machine tool 50 of this embodiment can easily calibrate the probe 60 used for measuring the workpiece.

[0074] (Second Implementation)

[0075] Hereinafter, the correction device 70 according to the second embodiment will be described with reference to FIGS. 11A to 11D. The same reference numerals are used for the same or corresponding components as in the first embodiment, and repeated descriptions are omitted.

[0076] Figures 11A to 11D show schematic top and side views of the correction device 70 with temporary stop mechanisms 74a and 76. As shown in Figures 11A and 11B, the outer cylinder 72 of the correction device 70 has a rectangular groove 72a extending horizontally, in which a prism-shaped locking shaft 76 is slidably disposed. Furthermore, a recess 74a matching the outer peripheral shape of the locking shaft 76 is formed on the lower side of the shaft portion 74. Therefore, by pressing the shaft portion 74 down to a position where the recess 74a aligns with the rectangular groove 72a, as shown in Figure 11B, and in this state, as shown in Figure 11A, inserting the locking shaft 76 into the rectangular groove 72a and the recess 74a, the locking shaft 76 engages with the recess 74a, thus locking the shaft portion 74, i.e., temporarily stopping it. Furthermore, as shown in Figure 11C, when the locking shaft 76 is pushed out from the rectangular slot 72a and the arc-shaped clearance portion 76a is aligned with the shaft portion 74, the engagement between the locking shaft 76 and the shaft portion 74A is released. Therefore, the temporary stop can be released, and as shown in Figure 11D, the released shaft portion 74 can be raised by the spring force of the coil spring 24.

[0077] According to the calibration device 70 of this embodiment, the shaft 74 can be temporarily stopped in the pressed-in position using the temporary stop mechanisms 74a and 76. Therefore, in order to set the position for fixing the shaft 74, it is only necessary to move the reference tool 58 of the machine tool 50 to the vicinity of the shaft 74 of the calibration device 10, release the temporary stop, and bring the shaft 74, which is under the force of the helical spring 24, into contact with the reference tool 58 of the machine tool 50, thus setting the position. As a result, it is possible to prevent or suppress the reference tool 58 from excessively pressing into the shaft 74 and thus suppressing the load on the machine tool 50, thereby ensuring the safety of the machine tool 50.

[0078] (Variation example)

[0079] Hereinafter, variations of the machine tool 50 according to the first and second embodiments will be described. Reference numerals that are the same as or correspond to those in the first and second embodiments will be used, and repeated descriptions will be omitted.

[0080] According to this modification, the reference tool 78 of the machine tool 50 has a safety structure with one or more radially slits 79a, 79b to reduce the rigidity of the reference tool 78. Therefore, when the reference tool 78 is moved toward the shaft portions 14, 74 of the correction devices 10, 70, if the reference tool 78 is mistakenly overpressed into the shaft portions 14, 74, the reference tool 78 can be prevented or suppressed from being transmitted to the reference tool 78 side due to excessive load. Thus, it is possible to prevent or suppress the reference tool 78 from overpressing into the shaft portions 14, 74 and thus preventing the machine tool 50 from being overloaded, ensuring the safety of the machine tool 50.

[0081] Furthermore, although the fixing part 16 is described with a pushing part 30, a cam rod 32, a covering part 34, and a contact part 31, it is not limited to this. For example, the fixing part may also be configured to have: a thin-walled cylindrical part that surrounds the outer periphery of the shaft; a cam rod that, when rotated, deforms and fixes the thin-walled cylindrical part through contact with the cam portion; and a contact part that contacts the cam rod when it is rotated in the direction of fixing the shaft. The following effects can be obtained: the shaft can be fixed simply by rotating the cam rod, and torque management can be easily performed using the contact part. Alternatively, the shaft can also be fixed using a bolt-fastening type of shaft clamp or the like provided on the outer periphery of the fastening part.

[0082] Furthermore, although the description focuses on the XY correction section 26 being formed on the outer periphery of the shaft section 14, it is not limited to this and can also be formed on the outer peripheral surface of the outer cylinder section. When the XY correction section is formed on the outer peripheral surface of the outer cylinder section, although the positional relationship between the XY correction section and the Z correction section changes due to the extension of the shaft section, and correction of this change is necessary, as with the case where the XY correction section is formed on the outer peripheral surface of the shaft section, alignment in the X-axis, Y-axis, and Z-axis directions can be easily performed using a single correction device.

[0083] Furthermore, although the description focuses on the outer cylinder 12 being fixed to the metal worktable 52 by magnet 22, it is not limited to this. It can also be detachably mounted to any position on the machine tool by means of bolts or other methods, or it can be permanently fixed to a designated position on the machine tool. In the case of a detachable mounting, since it is stored outside the machine tool when not in use, it is unaffected by chips and coolant. Additionally, if it can be detached, it can be used on multiple machine tools.

[0084] Furthermore, the placement of the calibration device on the machine tool and the fixing of the shaft that abuts against the reference tool by the fixing unit can be performed by a robot arm, while the mounting of the reference tool and the probe on the machine tool spindle can be performed by a tool changing device. Calibration can be performed automatically by the robot arm without operator intervention. Additionally, a temporary reference coordinate determining unit can be provided to determine temporary reference coordinates Xm1 and Ym1 from the coordinate information of the robot arm when the calibration device is placed on the machine tool, and a camera device can be provided to confirm the contact between the reference tool and the shaft before fixing the shaft. The machine tool control unit can also control the machine tool to perform calibration according to a preset cycle.

[0085] The embodiments of the correction devices 10 and 70, the correction method, and the machine tool 50 have been described above, but the present invention is not limited to the above embodiments. For example, instead of a vertical machine tool with the spindle facing vertically, a horizontal machine tool with the spindle facing horizontally could also be used. In this case, the correction device is mounted on the vertical plane of the worktable in a manner that makes the spindle horizontal. In addition to the above, those skilled in the art should understand that various modifications of the above embodiments are possible.

[0086] Explanation of reference numerals in the attached figures

[0087] 10. Calibration device

[0088] 12 Outer cylinder part

[0089] 12a First step (temporary stop mechanism)

[0090] 12b Second step (temporary stop mechanism)

[0091] 12d inclined surface

[0092] 14 Shaft section

[0093] 15. Retaining ring (temporary stop mechanism)

[0094] 16 Fixing Part

[0095] 18 Thin-walled cylindrical section

[0096] 22 magnets

[0097] 24. Coil spring (force application part)

[0098] 26 XY Calibration Department

[0099] 28 Z Correction Department

[0100] 30. Pressing part (clamp)

[0101] 32 Cam rod

[0102] 50 machine tools

[0103] 52 workbenches

[0104] 54 Spindle

[0105] 58 Benchmark Tools

[0106] 60 probe

Claims

1. A correction device for a measuring head used in a machine tool, characterized in that, Comprising: a shaft portion formed in a bar shape and capable of being extended from a correction device in an axial direction; an outer cylinder portion that supports the shaft portion on an inner side; a force applying portion that is disposed inside the outer cylinder portion and applies a force to the shaft portion in an extending direction; a temporary stop mechanism that stops the shaft portion at a pressed-in position against an action of the force applying portion; a fixing portion that is disposed on the outer cylinder portion and is capable of fixing the shaft portion with respect to the outer cylinder portion; an XY correction portion that is formed along an outer peripheral surface of the shaft portion or the outer cylinder portion; and a Z correction portion that is formed at a top end of the shaft portion and has a plane orthogonal to an axial direction of the shaft portion. The outer cylinder portion has a magnet at a bottom portion, and an inclined surface is formed in a part of the bottom portion, the inclined surface being inclined toward an outer peripheral side with respect to a radial direction of the bottom surface.

2. The correction device of claim 1, wherein, The outer cylinder portion has a thin-walled cylinder portion that supports the shaft portion, and the fixing portion has a clamp that can releasably apply a radial pressing force to the shaft portion from an outer periphery of the thin-walled cylinder portion.

3. The correction device of claim 1 or 2, wherein, Comprising:

4. A machine tool capable of mounting the correction device of claim 1, characterized in that, a main shaft for mounting a machining tool, and capable of mounting a reference tool and the probe instead of the machining tool; a table for mounting a machining object and the correction device; and a feed shaft portion for relatively moving the main shaft and the table. A top end of the reference tool mounted to the main shaft has a spherical shape having a radius identical to that of a ball portion of a probe needle of the probe.

5. The machine tool of claim 4, wherein, The reference tool mounted to the main shaft has a safety structure that is broken when a load of a prescribed value or more is applied.

6. The machine tool of claim 4 or 5, wherein, Comprising:

7. A method of calibrating the probe of claim 1 using the calibration device, characterized by, arranging the correction device to the machine tool; stopping the shaft portion at a pressed-in position by the temporary stop mechanism; mounting a reference tool to a main shaft of the machine tool, relatively moving the main shaft so that a top end of the reference tool is positioned on an upper side in an axial direction of the Z correction portion of the shaft portion; releasing the temporary stop mechanism, and applying a force to the shaft portion by the force applying portion toward the reference tool; fixing the shaft portion abutting against the reference tool by the fixing portion; acquiring a reference coordinate in the axial direction of the fixed shaft portion; mounting the probe to the main shaft of the machine tool; acquiring a reference coordinate in a direction orthogonal to the axial direction of the shaft portion; acquiring correction values in the axial direction and the direction orthogonal to the axial direction based on the reference coordinates. ​

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