Calibration device, calibration method, and machine tool

Abstract

To provide a calibration device and a calibration method which prevent excessive pressing of a reference tool into the calibration device during the calibration work and suppress reduction in work efficiency caused by excessive caution during the calibration work by fearing the excessive pressing and have high safety and excellent operability, and a machine tool using the same.SOLUTION: A calibration device 10 comprises: a shaft part 14 which can advance from the calibration device 10 along an axial direction; an outer cylindrical part 12 which supports the shaft part 14 on an inner side; a coil spring 24 which is arranged inside the outer cylindrical part 12 and biases the shaft part 14 in the advancing direction; temporary holding mechanisms 12a, 12b, 15 which hold the shaft part 14 at a pressed position against the biasing force of the coil spring 24; a fixing part 16 which is arranged in the outer cylindrical part 12 and capable of fixing the shaft part 14 relative to the outer cylindrical part 12; an XY calibration part 26 which is formed along the outer circumferential surface of the shaft part 14; and a Z calibration part 28 which is formed at a tip of the shaft part 14 and has a plane perpendicular to the axial direction of the shaft part 14.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a calibration device, a calibration method, and a machine tool. [Background technology]

[0002] To perform machining with high accuracy, machine tools require position information, i.e., coordinates, of the workpiece to be machined. The position information is obtained by manual measurement by an operator after the operator mounts the workpiece on the machine tool at the machining site, or by measurement using a measuring device equipped with a sensor that is attached to the machine tool. The measuring device here refers to a measurement system that has a sensor, so it is necessary to recognize measurement errors using a reference gauge or the like and calibrate the measurement results. This type of calibration work is also called calibration work, and the accuracy of the measurement results strongly depends on the accuracy of the calibration work.

[0003] Patent Document 1 discloses a calibration device for a machine tool, including a base that can be attached to the machine tool and a spherical calibration artifact. However, the coordinate origin in the vertical direction, i.e., the Z-axis direction, needs to be manually acquired using a reference tool and a gauge block. Specifically, the measurer needs to manually lower the tool until the gauge block is sandwiched between the reference tool and the sphere, and the calibration work is complicated even when the calibration device is used. In addition, the calibration work in the horizontal direction, i.e., the X-axis and Y-axis coordinates and the Z-axis coordinate, needs to be performed separately. This increases the work time and labor required for the calibration work. Furthermore, since the calibration work involving manual labor requires skill, the measurement accuracy varies depending on the skill of the measurer, and it is not easy to teach the skills related to such complicated work to others.

[0004] For example, Patent Document 2 discloses a calibration device for a coordinate positioning machine, which includes a base, a calibration artifact, and a lockable mechanism for attaching the calibration artifact to the base. Here, the lockable mechanism of the calibration device can adopt an unlocked state in which the calibration artifact is movable relative to the base by application of an external force, and a locked state in which the position of the calibration artifact is locked relative to the base. However, when a bar (a reference tool with a known length) held by a spindle of a machine tool is brought into contact with a calibration artifact (calibration sphere) for alignment, a situation may occur in which the bar is moved too far toward the calibration sphere by mistake. This may not only damage the calibration device, but also place a large load on the spindle and machine tool via the bar. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2019-509902 [Patent Document 2] Special Publication No. 2023-519290 Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above circumstances, the present invention aims to provide a calibration device and calibration method that prevents a reference tool from being excessively pressed into the calibration device during calibration work and suppresses a decrease in work efficiency caused by being overly cautious during calibration work for fear of excessive pressing, thereby providing a highly safe and easy-to-use calibration device and calibration method, as well as a machine tool using these. [Means for solving the problem]

[0007] According to one aspect of the present invention, there is provided a calibration device for a touch probe used in a machine tool, the calibration device comprising: a rod-shaped shaft portion capable of advancing from the calibration device along an axial direction; an outer tube portion supporting the shaft portion on the inside; a biasing portion disposed inside the outer tube portion and biasing the shaft portion in the advancing direction; a temporary fixing mechanism for fixing the shaft portion in a position where it is pushed in against the biasing force of the biasing portion; a fixing portion disposed on the outer tube portion and capable of fixing the shaft portion to the outer tube portion; an XY calibration portion formed along the outer peripheral surface of the shaft portion or the outer tube portion; and a Z calibration portion formed at the tip of the shaft portion and having a plane perpendicular to the axial direction of the shaft portion.

[0008] Furthermore, according to one aspect of the present invention, there is provided a machine tool to which a calibration device relating to one aspect of the present invention can be attached, the machine tool comprising: a spindle for attaching a machining tool, the spindle to which a reference tool and a touch probe can be attached instead of the machining tool; a table to which the workpiece and the calibration device are attached; and a feed axis section for moving the spindle and the table relative to one another.

[0009] According to one aspect of the present invention, there is provided a method for calibrating a touch probe using a calibration device according to one aspect of the present invention, the calibration method including: placing the calibration device on a machine tool; fixing a shaft portion in a pushed-in position by a temporary fixing mechanism; attaching a reference tool to a spindle of the machine tool and relatively moving the spindle so that the tip of the reference tool is located axially above the Z calibration portion of the shaft portion; releasing the temporary fixing mechanism and biasing the shaft portion toward the reference tool by a biasing portion; fixing the shaft portion abutting against the reference tool with a fixing portion; obtaining a reference coordinate in the axial direction of the fixed shaft portion; attaching the touch probe to the spindle of the machine tool; obtaining a reference coordinate in a direction perpendicular to the axial direction of the shaft portion; and obtaining calibration values ​​in the axial direction and in a direction perpendicular to the axial direction based on the reference coordinate. Effect of the Invention

[0010] According to one aspect of the present invention, the calibration device includes a shaft portion that can be advanced from the calibration device along the axial direction, a biasing portion that biases the shaft portion in the advancing direction, a temporary locking mechanism that holds the shaft portion in a position where it is pushed in against the biasing force of the biasing portion, and a fixing portion that can fix the shaft portion to the outer tube portion. Therefore, since the shaft portion can be biased by the biasing portion and fixed in the advanced position, the positioning of the shaft portion in the axial direction can be performed easily and in a short time. In addition, the shaft portion can be temporarily fixed in the pressed-in position by the temporary locking mechanism. Therefore, in order to set the position where the shaft portion is fixed, it is sufficient that the tip portion of the reference tool attached to the spindle of the machine tool is moved to the vicinity of the shaft portion of the calibration device, and the position can be set by releasing the temporary locking and bringing the shaft portion biased by the biasing portion into contact with the tip portion of the reference tool attached to the spindle of the machine tool. This prevents the tip of the reference tool from colliding with the shaft portion and applying a load to the machine tool, and since there is no need to perform the careful task of pushing the shaft portion by a predetermined amount with the reference tool, it is possible to suppress a decrease in work efficiency and ensure the safety of the machine tool. Furthermore, the calibration device includes an XY calibration section formed along the outer circumferential surface of the shaft portion, and a Z calibration section formed at the tip of the shaft portion and having a plane perpendicular to the axial direction of the shaft portion. Therefore, alignment in the direction along the shaft portion and in the direction perpendicular to the shaft portion can be easily performed with one shaft portion, i.e., the calibration device. This allows the calibration work to be performed easily and with good operability without depending on the skill level of the operator, and such calibration work can be performed regularly without any hassle, so the quality of the processed product, i.e., the processing accuracy, can be stabilized.

[0011] According to the machine tool of one aspect of the present invention, the calibration device of one aspect of the present invention can be attached, and a reference tool and a touch probe can be attached to the spindle. Therefore, the calibration work can be performed easily and in a short time. Furthermore, it is possible to prevent or suppress the tip of the reference tool attached to the spindle of the machine tool from colliding with the shaft portion and applying a load to the machine tool, thereby ensuring the safety of the machine tool.

[0012] According to a calibration method according to one aspect of the present invention, alignment in a direction along the shaft portion and in a direction perpendicular to the shaft portion can be continuously performed by one calibration device. This allows calibration work to be performed simply and in a short time. Furthermore, it is possible to prevent or suppress the tip of a reference tool attached to the spindle of a machine tool from colliding with the shaft portion and applying a load to the machine tool, thereby ensuring the safety of the machine tool. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 shows a perspective view of a calibration device according to the first embodiment. [Diagram 2] FIG. 2 is a perspective view showing the calibration device with the shaft portion advanced. [Figure 3A-3B] 3A shows a cross-sectional view of the calibration device with the shaft raised along line 3-3 in FIG. 1, and FIG. 3B shows a cross-sectional view of the calibration device of FIG. 3A along line 3B-3B. [Figure 3C-3D] 3C shows a cross-sectional view of the calibration device taken along line 3-3 in FIG. 1 with the shaft portion temporarily fixed in the pushed-in position, and FIG. 3D shows a cross-sectional view of the calibration device taken along line 3D-3D in FIG. 3C. [Fig. 3E-3F] FIG. 3E shows a cross-sectional view of the calibration device taken along line 3-3 in FIG. 1 with the shaft portion in contact with the tip portion of the reference tool after the temporary fixation has been released, and FIG. 3F shows a cross-sectional view of the calibration device of FIG. 3E taken along line 3F-3F. [Figure 3G-3H] 3G shows a cross-sectional view of the calibration device with the shaft portion fixed, taken along line 3-3 in FIG. 1, and FIG. 3H shows a cross-sectional view of the calibration device of FIG. 3G, taken along line 3H-3H. [Figure 4A] FIG. 4A shows a perspective view of the calibration device with the cover removed. [Figure 4B] FIG. 4B shows a cross-sectional view of the calibration device with the cam lever in an unclamped state, taken along line 4-4 in FIG. [Figure 4C] FIG. 4C shows a cross-sectional view of the calibration device with the cam lever in a clamped state, taken along line 4-4 in FIG. [Figure 5A-5B] FIG. 5A shows a side view of the calibration device, and FIG. 5B shows a bottom view of the calibration device of FIG. 5A. [Fig. 5C-5D] FIG. 5C shows a side view of the calibration device when attached to a table, and FIG. 5D shows a side view of the calibration device when removed from the table. [Figure 6] Figure 6 shows a flow chart of the touch probe calibration process. [Figure 7] FIG. 7 shows a side view of a machine tool with a reference tool and a calibration fixture mounted thereon. [Figure 8] FIG. 8 shows a plan view of the Z calibration unit showing the relationship between the provisional reference coordinates and the reference coordinates. [Figure 9] FIG. 9 shows a perspective view for explaining a method for calibrating a touch probe. [Figure 10] FIG. 10 is a plan view for explaining a method of acquiring reference coordinates in the X-axis and Y-axis directions. [Figure 11A-11B] 11A-11B are schematic plan and side views of the state in which the shaft portion is clamped by the temporary fastening mechanism according to the second embodiment, and are cross-sectional views taken along lines 11A-11A and 11B-11B, respectively. [Fig. 11C-11D] 11C-11D are schematic diagrams showing the state in which the shaft portion is unclamped by the temporary fastening mechanism of the second embodiment, in plan and side views, and are cross-sectional views taken along lines 11C-11C and 11D-11D, respectively. [Figure 12] FIG. 12 shows a side view of a modified reference tool. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, a calibration device, a machine tool, and a calibration method according to embodiments will be described with reference to the accompanying drawings. Similar or corresponding elements are given the same reference numerals, and duplicated explanations will be omitted. In order to facilitate understanding, the scale of the drawings may be changed.

[0015] (First embodiment) Hereinafter, a first embodiment of the present invention will be described with reference to the accompanying drawings. Figs. 1 and 2 show perspective views of a calibration device 10. As shown in Figs. 7 and 9, the calibration device 10 is used in a machine tool 50 to calibrate the position of a touch probe 60 for the purpose of accurately measuring the position of a workpiece (not shown). For this reason, the calibration device 10 is attached to a table 52 of the machine tool 50 on which a workpiece (not shown) to be processed is attached. In the drawings, arrows indicate the front-rear direction, left-right direction, and up-down direction of the machine tool 50 when the machine tool 50 is placed on a horizontal plane such as the floor of a factory or the like. In the drawings, X indicates the left-right direction of the machine (X-axis direction), Y indicates the front-rear direction of the machine (Y-axis direction), and Z indicates the up-down direction of the machine (Z-axis direction).

[0016] 1 and 2, the calibration device 10 includes an outer cylinder portion 12, a shaft portion 14, and a fixing portion 16 (see FIG. 4A). In the calibration device 10, the outer cylinder portion 12 is placed on the upper surface of a table 52 (see FIG. 7) of a machine tool 50, and the metal shaft portion 14 formed in a rod shape is advanced toward the upper side of the outer cylinder portion 12. At this time, the fixing portion 16 is formed to fix the position of the advanced shaft portion 14.

[0017] As shown in Figures 1 and 3A, the outer cylinder 12 is made of metal and has a cylindrical outer circumferential shape. A cylindrical thin-walled cylindrical portion 18 for fastening the shaft portion 14 is formed integrally with the outer cylinder 12 at the center of the upper side of the outer cylinder 12. A hole 20 is formed penetrating the center of the thin-walled cylindrical portion 18 and the outer cylinder 12 along the axial direction of the shaft portion 14 housed in the outer cylinder 12 and the thin-walled cylindrical portion 18, i.e., the Z-axis direction. The inner diameter of the hole 20 in the upper part of the thin-walled cylindrical portion 18 and the outer cylinder 12 is formed to be approximately the same as the outer diameter of the shaft portion 14 so that the shaft portion 14 can be housed and fastened.

[0018] As shown in FIG. 3A, a disk-shaped magnet 22 is disposed on the bottom side of the outer cylinder 12 so as to close the hole 20. This makes it possible to stabilize the position of the calibration device 10 disposed on a metal table 52 (see FIG. 7) so as not to shift. A coil spring 24 is disposed between the lower end of the shaft 14 housed in the hole 20 and the magnet 22 as a biasing part. This makes it possible to bias the shaft 14 housed in the hole 20 upward, that is, toward the reference tool 58 and the touch probe 60 (see FIGS. 7 and 9). This allows the shaft 14 to abut against the tip of the reference tool 58 disposed above the shaft 14. The tip of the reference tool 58 is preferably spherical.

[0019] An XY calibration section 26 having a cylindrical outer circumferential shape is formed on the upper side of the shaft section 14 housed in the hole 20. The XY calibration section 26 extends further in the radial direction of the shaft section 14 than other parts of the shaft section 14, and is formed so that its central axis coincides with the central axis of the shaft section 14.

[0020] At the tip of the shaft 14, a Z calibration section 28 is formed having a plane perpendicular to the axial direction of the shaft 14, i.e., parallel to the mounting surface AS (see FIG. 5C) of the table 52 on which the calibration device 10 is mounted. Here, even if the reference tool 58 abuts at any position in the X-axis direction or Y-axis direction on the plane of the Z calibration section 28, the relative difference between the Z-axis direction position at the position in the X-axis direction or Y-axis direction where the reference tool 58 abuts and the Z-axis direction position at the central axis position of the XY calibration section 26 can be measured by the touch probe 60, thereby obtaining an accurate Z-axis direction position at the central axis position of the XY calibration section 26 on the plane of the Z calibration section 28. Therefore, positioning in the X-axis direction and the Y-axis direction when the reference tool 58 abuts can be performed easily and in a short time.

[0021] As shown in FIG. 3A and FIG. 3B, a retaining ring 15 is attached to the lower end of the shaft portion 14. The retaining ring 15 is formed in a ring shape along the outer peripheral shape of the shaft portion 14 and constitutes a temporary fastening mechanism. A part of the outer peripheral part of the retaining ring 15 has a hook portion 15a extending radially outward, i.e., toward the radially outer side of the shaft portion 14. In addition, a first step portion 12a and a second step portion 12b constituting the temporary fastening mechanism are formed in a stepped shape on the lower side of the hole portion 20 of the outer tube portion 12. Specifically, the first step 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 step portion 12b is formed concentrically with the hole portion 20 and the first step portion 12a on the lower side of the first step portion 12a and has an inner diameter larger than the inner diameter of the first step portion 12a. Furthermore, second step 12b is formed with a cutout in part so that hook 15a can pass when shaft 14, to which snap ring 15 is attached, moves up and down. Since snap ring 15 abuts against the upper end of first step 12a, which communicates with hole 20 toward the upper side, upward movement of shaft 14 is restricted at this position.

[0022] 3C and 3D, when the shaft portion 14 is pushed downward to the second step portion 12b against the biasing force of the coil spring 24, i.e., the spring force, and the shaft portion 14 is rotated to a position where the hook portion 15a and the cutout portion of the second step portion 12b do not overlap in a bottom view, the hook portion 15a of the retaining ring 15 abuts against the second step portion 12b, restricting the upward movement of the shaft portion 14 at this position. Therefore, the shaft portion 14 can be temporarily fixed by being stopped at this position. Here, the hook portion 15a is rotated about 90 degrees from the cutout portion of the second step portion 12b.

[0023] 3E and 3F, when the tip of the reference tool 58 (see FIG. 7) is moved a predetermined distance above the temporarily fixed shaft 14, the shaft 14 is rotated to pass the hook 15a through the notched portion of the second step 12b, and the shaft 14 is raised by the spring force of the coil spring 24. Therefore, the Z calibration part 28 can be brought into contact with the tip of the reference tool 58 by the movement of the shaft 14.

[0024] Furthermore, as shown in Figures 3G and 3H, with the Z calibration portion 28 abutting the tip of the reference tool 58, the height position of the shaft portion 14 in the calibration device 10 can be fixed by rotating the cam lever 32 to clamp the shaft portion 14, as described below.

[0025] 4A shows a perspective view of the calibration device 10 with the shaft portion 14 and the cover portion 34 removed. The fixing portion 16 (see FIG. 4A) formed on the radially outer side of the thin-walled cylindrical portion 18 has a pressing portion 30 serving as a metallic clamper for pressing the thin-walled cylindrical portion 18, a metallic cam lever 32 for applying pressure to the pressing portion 30, a hard resin covering portion 34 arranged to cover the outside of the pressing portion 30, and an abutment portion 31 (see FIG. 4C) against which the cam lever 32 abuts. Note that, although the covering portion 34 is described here as being made of hard resin, this is not limiting and the covering portion may be made of a material other than hard resin.

[0026] As shown in Fig. 4A to Fig. 4C, the pressing part 30 is formed so as to surround, i.e., to sandwich, the outside of the thin-walled cylindrical part 18, and has an inner part 36 whose inner width is formed to be the same as the outer diameter of the thin-walled cylindrical part 18. One longitudinal end of the pressing part 30 is fastened to the outer tube part 12 with a bolt 29, and the other longitudinal end is formed with a gap 30a that penetrates to the inner part 36. Furthermore, a rod-shaped pin 40 is attached to the other longitudinal end of the pressing part 30, the shaft part of which passes through the gap 30a and extends to the inside of the pressing part 30. A collar 38 is attached to the pin 40 exposed from the pressing part 30, and a cam lever 32 is rotatably connected to the end of the pin 40 with a screw 33.

[0027] The cam lever 32 is formed to be rotatable in the horizontal direction around a central axis extending along the Z-axis direction. The cam lever 32 has a cam portion 32a formed in a cam shape on the central axis side, and a lever portion 32b extending from the cam portion 32a in the radial direction of the central axis, here, in the horizontal direction. Therefore, when the lever portion 32b is rotated toward the side where it abuts against the abutment portion 31 from the unclamped state of the shaft portion 14 as shown in FIG. 4B, the cam portion 32a presses the pressing portion 30 via the collar 38 as shown in FIG. 4C, and the gap 30a is closed by elastic deformation, and the inner portion 36 presses the thin-walled cylindrical portion 18 radially inwardly from both sides evenly. As a result, the thin-walled cylindrical portion 18 is elastically crushed to tighten the shaft portion 14, and the shaft portion 14 is clamped to fix the shaft portion 14 to the thin-walled cylindrical portion 18 without losing the position and posture of the shaft portion 14 abutting against the reference tool 58. Additionally, screws 42, 44 are attached to the pressing portion 30 for fixing the end of the pin 40 on the pressing portion 30 side and the side of the pin 40. Therefore, when the cam lever 32 is rotated from the unclamped state to the clamped state, the pressing portion 30 can be stably pulled in by the lift amount of the cam portion 32a, and the thin-walled cylindrical portion 18 and the shaft portion 14 can be stably clamped.

[0028] 4C, when the lever portion 32b is rotated away from the abutment portion 31 to set the unclamped state shown in FIG. 4B, the collar 38, the pressing portion 30, and the thin-walled cylindrical portion 18 are no longer pressed by the cam portion 32a. Therefore, the thin-walled cylindrical portion 18 releases the shaft portion 14, and the shaft portion 14 can advance upward by the spring force of the coil spring 24.

[0029] 5A and 5B show a side view and a bottom view of the calibration device 10. At the bottom of the outer tubular part 12, an inclined surface 12d is formed on a part of the radially outer side of the magnet 22 arranged at the center, the inclined surface 12d being inclined radially toward the outer periphery and upward of the outer tubular part 12 with respect to the radial direction of the bottom surface. The bolt 35 is a bolt that fixes the cover part 34 to the outer tubular part 12.

[0030] 5C and 5D show side views of the calibration device 10 when it is attached to and detached from the mounting surface AS of the table 52 (see FIG. 7). As shown in FIG. 5C, when the calibration device 10 is attached to the mounting surface AS, the calibration device 10 is tilted and arranged so that the inclined surface 12d abuts against the mounting surface AS, and from this state, the calibration device 10 can be tilted in the direction of the arrow in the figure with the inclined surface 12d as a fulcrum, and the bottom surface of the outer cylinder part 12 can be abutted against the mounting surface AS. Also, as shown in FIG. 5D, when the calibration device 10 is detached from the mounting surface AS, the calibration device 10 is tilted in the direction of the arrow in the figure to abut the inclined surface 12d against the mounting surface AS, so that the magnet 22 is separated from the mounting surface AS, and the calibration device 10 can be detached from the mounting surface AS in a state where the magnet 22 is not in direct contact with the mounting surface AS. Therefore, it is possible to prevent or suppress the calibration device 10 from abutting forcefully against the mounting surface AS, that is, from colliding with it, due to the magnetic force of the magnet 22. Furthermore, since there is no need to pull up the calibration device 10 in the direction in which the magnetic force acts, i.e., in the vertical direction, the calibration device 10 can be easily and efficiently removed from the mounting surface AS. This makes it possible to prevent or suppress damage to the mounting surface AS when mounting and removing the calibration device 10. Also, since a typical magnet stand system with a magnetic force on / off switching lever is not used, the calibration device 10 can be quickly mounted on and removed from the table 52.

[0031] The effects of the calibration device 10, the calibration method, and the machine tool 50 according to this embodiment will be described below through an explanation of the calibration method following the flow chart shown in FIG.

[0032] First, proceed to step S10 and install the calibration device 10 on the table 52 of the machine tool 50 that calibrates the touch probe 60 for measuring the workpiece, as shown in Fig. 7. Here, the calibration device 10 is installed so that the upper surface (plane) of the Z calibration unit 28 is parallel to the lower end surface of the spindle 54 for mounting a tool of the machine tool 50, that is, so that the plane of the Z calibration unit 28 is horizontal.

[0033] Next, the process proceeds to step S20, where the shaft portion 14 is temporarily fixed by pushing the shaft portion 14 into the outer cylinder portion 12 and rotating it, as shown in Figs. 3C and 3D. Then, the process proceeds to step S30, where the reference tool 58 attached to the tool holder 56, whose length LT is known, is attached to the spindle 54, and the process proceeds to step S40, where the reference tool 58 is positioned. The reference tool 58 is positioned so that the tip end, here the lower end, of the reference tool 58 is positioned above the Z calibration portion 28 of the shaft portion 14 with a predetermined interval by a feed shaft device (not shown) that is disposed on the machine tool 50 and serves as a feed shaft portion for moving the spindle 54 along the X-axis, Y-axis, and Z-axis directions. The predetermined interval may be anywhere within the stroke range between the temporary fixing position and the raised position of the shaft portion 14, and for example, about 4 mm is selected if the stroke is 7 mm. Since there is no work of pushing the shaft portion 14 while the reference tool 58 is in contact with the shaft portion 14, collision can be prevented.

[0034] When the reference tool 58 is positioned, the process proceeds to step S50, where the shaft 14 is rotated to release the temporary fastening, and the spring force urges the shaft 14 upward, as shown in Figures 3E and 3F. This allows the Z calibration part 28 to abut against the lower end of the reference tool 58, as shown in Figure 7. When the Z calibration part 28 abuts, the process proceeds to step S60, where, with the Z calibration part 28 and the reference tool 58 abutting against each other, the cam lever 32 is rotated toward the abutment part 31 to fix the shaft 14, as shown in Figures 3G and 3H.

[0035] 8, the position where the tip of the reference tool 58 abuts on the plane of the Z calibration unit 28 is obtained (step S70), and is set as the reference Z coordinate Zm in the Z axis direction. Furthermore, the position in the X axis direction and the Y axis direction where the reference Z coordinate Zm is set is not necessarily the center of the Z calibration unit 28, i.e., the reference coordinate (Xm, Ym). Therefore, the position where the tip of the reference tool 58 abuts on the plane of the Z calibration unit 28 is measured, and is set as the tentative reference coordinate (Xm1, Ym1) in the X axis direction and the Y axis direction.

[0036] When the reference Z coordinate Zm and the temporary reference coordinate (Xm1, Ym1) are set, the process proceeds to step S80, where the touch probe 60 shown in FIG. 7 is attached to the spindle 54 instead of the reference tool 58. Next, the process proceeds to step S90, where the probe 62 disposed at the tip of the touch probe 60 is positioned at the temporary reference coordinate (Xm1, Ym1). Then, the process proceeds to step S100, where the position of the X-axis, Y-axis, and Z-axis is calibrated by the touch probe 60 thus attached to the spindle 54. The tip of the reference tool 58 may be of various shapes, such as flat, pointed, spherical, or an actual cutting tool. There is no guarantee that the plane of the Z calibration part 28 at the tip of the shaft part 14 is microscopically perpendicular to the axis of the spindle 54 of the machine tool 50, nor is there any guarantee that it is completely flat. Therefore, a spherical shape that provides point contact is usually selected for the tip of the reference tool 58 that contacts the Z calibration part 28. However, strictly speaking, it is considered that a very slight difference occurs in the contact position between the reference tool 58 and the probe 62 with respect to the Z calibration unit 28 in the temporary reference coordinates (Xm1, Ym1). In order to achieve high-precision measurement in which this difference is reduced to as close to zero as possible, it is preferable to form the tip of the reference tool 58 into a spherical shape with a radius R that is the same dimension as the spherical radius R of the probe 62.

[0037] The calibration of the X-axis, Y-axis, and Z-axis positions in step S90 and step S100 will be specifically described. First, the reference coordinates (Xm, Ym) in the X-axis and Y-axis directions are acquired. The touch probe 60 can emit a signal when it comes into contact with the measurement object. The machine tool is equipped with a control device and a receiving device for receiving the signal, and can detect that the touch probe 60 has come into contact with the measurement object. The measuring element 62 of the touch probe 60 is controlled so that it always faces the same phase with respect to the moving direction during measurement to acquire the reference coordinates (Xm, Ym). As shown in FIG. 10, the machine tool 50 relatively moves the spindle 54 by the feed axis device, and moves the measuring element 62 of the touch probe 60 located at the temporary reference coordinates (Xm1, Ym1) in the X-axis positive direction (X-axis + direction) along the path C3 (see FIG. 9). The X coordinate is measured at the position C3P where the moved measuring element 62 comes into contact with the XY calibration unit 26. Furthermore, the probe 62 of the touch probe 60 is moved in the negative direction of the X axis (- direction of the X axis) along path C4 (see FIG. 9). The X coordinate is measured at position C4P where the moved probe 62 comes into contact with the XY calibration unit 26. 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 a first X coordinate at the intermediate position between positions C3P and C4P.

[0038] Furthermore, the machine tool 50 relatively moves the spindle 54 by the feed axis device, and moves the probe 62 of the touch probe 60, whose X coordinate is set as the first X coordinate, in the Y-axis positive direction (Y-axis + direction) along a path C5 (see FIG. 9). The Y coordinate is measured at a position where the moved probe 62 contacts the XY calibration unit 26. The machine tool 50 also moves the probe 62 of the touch probe 60 in the Y-axis negative direction (Y-axis - direction) along a path C6 (see FIG. 9). The machine tool 50 measures the Y coordinate at a position where the moved probe 62 contacts the XY calibration unit 26. Here, since the X coordinates at the two locations are constant as the first X coordinate, the machine tool 50 can calculate the average value of these Y coordinates as the Y coordinate at the intermediate position, i.e., the reference coordinate Ym.

[0039] Furthermore, the machine tool 50 relatively moves the spindle 54 by the feed axis device, and moves the probe 62 of the touch probe 60, whose Y coordinate is the reference coordinate Ym, in the positive direction of the X axis along the path C3. The X coordinate is measured at the position where the moved probe 62 contacts the XY calibration unit 26. The machine tool 50 also moves the probe 62 of the touch probe 60 in the negative direction of the X axis along the path C4. The X coordinate is measured at the position where the moved probe 62 contacts the XY calibration unit 26. Here, since the Y coordinates of the two locations are constant at Ym, the machine tool 50 can calculate the average value of these X coordinates as the X coordinate at the intermediate position, i.e., the reference coordinate Xm. This positions the probe 62 of the touch probe 60 at the reference coordinate (Xm, Ym).

[0040] As shown in FIG. 9, the probe 62 of the touch probe 60 positioned at the reference coordinates (Xm, Ym) performs calibration measurements of the X-axis and Y-axis positions. First, the probe 62 of the touch probe 60 is positioned in the X-axis + direction, i.e., moves along the path C3. Calibration measurements are performed in the X-axis + direction at a position where the moved probe 62 comes into contact with the XY calibration unit 26, and calibration values ​​(X and Y coordinates) in the X-axis + direction are obtained. In addition, the probe 62 of the touch probe 60 is positioned in the X-axis negative direction (X-axis - direction), i.e., moves along the path C4. Calibration measurements are performed in the X-axis - direction at a position where the moved probe 62 comes into contact with the XY calibration unit 26, and calibration values ​​(X and Y coordinates) in the X-axis - direction are obtained.

[0041] Furthermore, the probe 62 of the touch probe 60 is positioned in the Y-axis + direction, i.e., it moves along the path C5. At a position where the moved probe 62 comes into contact with the XY calibration unit 26, a calibration measurement in the Y-axis + direction is performed, and a calibration value (X coordinate and Y coordinate) in the Y-axis + direction is obtained. Furthermore, the probe 62 of the touch probe 60 is positioned in the Y-axis - direction, i.e., it moves along the path C6. At a position where the moved probe 62 comes into contact with the XY calibration unit 26, a calibration measurement in the Y-axis - direction is performed, and a calibration value (X coordinate and Y coordinate) in the Y-axis - direction is obtained. The acquisition of the calibration values ​​in the X-axis + direction, the X-axis - direction, the Y-axis + direction, and the Y-axis - direction is repeated multiple times, and the average value is stored, i.e., recorded, in the machine tool 50 as the calibration value.

[0042] The machine tool 50 calculates the amount of eccentricity of the probe 62 of the touch probe 60 relative to the spindle 54 from the calibration values ​​in the positive X-axis direction, negative X-axis direction, positive Y-axis direction, and negative Y-axis direction, and positions it from the reference coordinate (Xm, Ym) to the reference coordinate (Xm2, Ym2) that takes the amount of eccentricity into consideration (C7 in the figure). The probe 62 of the touch probe 60 that has been positioned to the reference coordinate (Xm2, Ym2) that takes the amount of eccentricity into consideration in this way is further positioned in the negative Z-axis direction (Z-axis direction), that is, moved along the path C8. At the position where the moved probe 62 comes into contact with the Z calibration unit 28, a calibration measurement in the negative Z-axis direction is performed, and a calibration value (Z coordinate) in the negative Z-axis direction is obtained. This is repeated multiple times, and the average value is recorded in the machine tool 50 as the calibration value.

[0043] According to the calibration device 10, the calibration method, and the machine tool 50 of the present embodiment, the shaft portion 14 on which the Z calibration portion 28 is formed can be advanced from the outer cylinder portion 12 along the Z axis direction by the coil spring 24, and the shaft portion 14 can be fixed by the fixing portion 16 at the advanced position, i.e., the position where the tip of the reference tool 58 abuts against the Z calibration portion 28. Therefore, the reference tool 58 can be easily aligned in the Z axis direction. In addition, in order to perform the calibration work of the touch probe 60, it is necessary to obtain reference coordinates in the X axis, Y axis, and Z axis directions. However, in the existing means, it was necessary to manually perform the work of gradually approaching the reference tool, whose tool length LT is known, in units of several μm, and inserting and removing the gauge block to check the contact. Therefore, the alignment took a very long time, and there was also a risk of collision between the reference tool and the gauge block due to erroneous operation. However, in this embodiment, the reference tool 58 only needs to be brought close to the Z calibration portion 28 to a predetermined position before the alignment in the Z axis direction, and the Z calibration portion can be aligned safely and with good operability.

[0044] Moreover, according to the calibration device 10, the calibration method, and the machine tool 50 of the present embodiment, the shaft portion 14 can be temporarily fixed at a pressed-in position by the temporary fixing mechanisms 12a, 12b, and 15. Therefore, in order to set the position at which the shaft portion 14 is fixed, the reference tool 58 of the machine tool 50 only needs to be moved close to the shaft portion 14 of the calibration device 10, and the position can be set by releasing the temporary fixation and bringing the shaft portion 14 biased by the coil spring 24 into contact with the reference tool 58 of the machine tool 50. This makes it possible to prevent or suppress the reference tool 58 from pressing the shaft portion 14 too far and applying a load to the machine tool 50, thereby ensuring the safety of the machine tool 50.

[0045] Furthermore, according to the calibration device 10, the calibration method, and the machine tool 50 of the present embodiment, the calibration device 10 includes an XY calibration section 26 formed along the outer peripheral surface of the shaft section 14, and a Z calibration section 28 formed at the tip of the shaft section 14 and having a plane perpendicular to the Z-axis direction. Therefore, alignment in the X-axis direction, the Y-axis direction, and the Z-axis direction can be easily performed by one shaft section 14, i.e., the calibration device 10. This allows the calibration work to be performed without depending on the skill level of the worker. Furthermore, since such a simple calibration work can be performed periodically, the quality of the processed product, i.e., the processing accuracy, can be stabilized.

[0046] According to the machine tool 50 according to this embodiment, the calibration device 10 can be attached to the machine tool 50, and a reference tool 58 and a touch probe 60 can be attached to the spindle 54 of the machine tool 50. Therefore, the calibration work can be performed easily and quickly with good operability.

[0047] According to the calibration method of this embodiment, alignment in the Z-axis direction along the axial direction of the shaft portion 14 and in the X-axis direction and Y-axis direction perpendicular to the axial direction can be continuously performed by one calibration device 10. This allows calibration work to be performed easily and in a short time with good operability.

[0048] As described above, the calibration device 10, the calibration method, and the machine tool 50 according to the present embodiment can easily calibrate the touch probe 60 for measuring a workpiece.

[0049] Second embodiment 11A to 11D, a calibration device 70 according to the second embodiment will be described below. Elements similar to or corresponding to those in the first embodiment will be given the same reference numerals, and duplicated descriptions will be omitted.

[0050] 11A to 11D show schematic plan and side views of a calibration device 70 having temporary fastening mechanisms 74a and 76. As shown in FIGS. 11A and 11B, the outer cylinder 72 of the calibration device 70 has a square groove 72a formed penetrating along the horizontal direction, and a square column-shaped locking shaft 76 is slidably arranged in the square groove 72a. In addition, a recess 74a is formed on the lower side of the shaft 74 along the outer circumferential shape of the locking shaft 76. Therefore, as shown in FIG. 11B, the shaft 74 is pushed down to a position where the recess 74a and the square groove 72a face each other, and in that state, as shown in FIG. 11A, the locking shaft 76 is inserted into the square groove 72a and the recess 74a, so that the locking shaft 76 and the recess 74a engage with each other, thereby locking the shaft 74, i.e., temporarily fixing the shaft 74. Furthermore, as shown in FIG. 11C, when the locking shaft 76 is pushed out of the square groove 72a and the arc-shaped escape portion 76a faces the shaft portion 74, the engagement between the locking shaft 76 and the shaft portion 74A is released, so that the temporary fastening can be released. As shown in FIG. 11D, the spring force of the coil spring 24 can lift the disengaged shaft portion 74.

[0051] According to the calibration device 70 of this embodiment, the shaft portion 74 can be temporarily fixed at a pressed-in position by the temporary fixing mechanisms 74a, 76. Therefore, in order to set the position at which the shaft portion 74 is fixed, the reference tool 58 of the machine tool 50 only needs to be moved close to the shaft portion 74 of the calibration device 10, and the position can be set by releasing the temporary fixation and bringing the shaft portion 74 biased by the coil spring 24 into contact with the reference tool 58 of the machine tool 50. This makes it possible to prevent or suppress the reference tool 58 from pressing the shaft portion 74 too far and applying a load to the machine tool 50, thereby ensuring the safety of the machine tool 50.

[0052] (Modification) Modifications of the machine tool 50 according to the first and second embodiments will be described below. Elements similar to or corresponding to those in the first and second embodiments will be given the same reference numerals, and duplicated descriptions will be omitted.

[0053] The reference tool 78 of the machine tool 50 according to this modification has a fuse structure that has one or more notched portions 79a, 79b cut out along the radial direction to reduce the rigidity of the reference tool 78. Therefore, if the reference tool 78 accidentally pushes the shanks 14, 74 too far when moving the reference tool 78 toward the shanks 14, 74 of the calibration devices 10, 70, the reference tool 78 can be broken to prevent or suppress the load acting on the reference tool 78 from being transmitted to the reference tool 78 side. This makes it possible to prevent or suppress the reference tool 78 from pushing the shanks 14, 74 too far and applying a load to the machine tool 50, thereby ensuring the safety of the machine tool 50.

[0054] The fixing part 16 has been described as having the pressing part 30, the cam lever 32, the cover part 34, and the abutment part 31, but is not limited thereto. For example, the fixing part may be configured to have a thin-walled cylindrical part surrounding the outer periphery of the shaft part, a cam lever part that can deform and fix the thin-walled cylindrical part by contacting the cam part when rotated, and an abutment part against which the cam lever part abuts when the cam lever part is rotated in the direction to fix the shaft part. The shaft part can be fixed simply by rotating the cam lever part, and the torque can be easily controlled by the abutment part. Alternatively, the shaft part may be fixed by a screw-tightened round shaft clamp or the like provided on the outer periphery of the fastening part.

[0055] Also, although the XY calibration section 26 has been described as being formed on the outer periphery of the shaft section 14, this is not limiting and the XY calibration section may be formed on the outer periphery of the outer cylinder section. When the XY calibration section is formed on the outer periphery of the outer cylinder section, the positional relationship between the XY calibration section and the Z calibration section changes as the shaft section advances, and this change amount needs to be corrected. However, similar to the case where the XY calibration section is formed on the outer periphery of the shaft section, alignment in the X-axis direction, Y-axis direction, and Z-axis direction can be easily performed by one calibration device.

[0056] Furthermore, although the outer cylinder portion 12 has been described as being fixed to the metal table 52 by the magnet 22, the present invention is not limited to this, and may be detachably arranged at any position on the machine tool by means of bolt fastening or the like, or may be permanently fixed at a predetermined position on the machine tool. If it is detachably arranged, it can be stored outside the machine tool when not in use, and is therefore not affected by cutting chips or coolant. Furthermore, if it is detachable, it can be used on multiple machine tools.

[0057] In addition, the calibration device may be arranged on the machine tool and the shaft part abutting against the reference tool may be fixed by a fixing part using a manipulator, and the reference tool may be attached to the spindle of the machine tool and the touch probe may be attached to the spindle of the machine tool using a tool exchanger. Calibration can be performed automatically by the manipulator without the intervention of an operator. In addition, the machine tool may be provided with a temporary reference coordinate determination unit that determines temporary reference coordinates Xm1, Ym1 from coordinate information of the manipulator when the calibration device is arranged on the machine tool, and may be provided with an imaging device that confirms the abutment of the reference tool and the shaft part before fixing the shaft part. The control device of the machine tool may control the machine tool to perform calibration at a preset cycle.

[0058] Although the embodiments of the calibration device 10, 70, the calibration method, and the machine tool 50 have been described above, the present invention is not limited to the above embodiments. For example, instead of a vertical machine tool with a spindle oriented vertically, a horizontal machine tool with a spindle oriented horizontally may be used. In this case, the calibration device is attached to the vertical surface of the table so that the shaft is horizontal. In addition to the above, it is considered that a person skilled in the art would understand that various modifications of the above embodiments are possible. [Explanation of symbols]

[0059] 10 Calibration device 12 External cylinder 12a First step portion (temporary fastening mechanism) 12b Second step portion (temporary fastening mechanism) 12d slope 14 Shaft 15 Retaining ring (temporary locking mechanism) 16 Fixed part 18 Thin-walled cylindrical section 22 Magnet 24 Coil spring (biasing part) 26 XY calibration section 28 Z calibration section 30 Pressing part (clamper) 32 Cam lever 50 Machine tools 52 Table 54 Main axis 58 Reference tool 60 Touch Probe

Claims

1. 1. A calibration apparatus for a touch probe for use on a machine tool, comprising: a rod-shaped shaft portion that can be advanced from the calibration device along an axial direction; an outer cylinder portion that supports the shaft portion on the inside; a biasing portion disposed inside the outer cylinder portion and biasing the shaft portion in the advancing direction; a temporary locking mechanism that locks the shaft portion in a position where it is pressed against the biasing force of the biasing portion; a fixing portion disposed on the outer tubular portion and capable of fixing the shaft portion to the outer tubular portion; An XY calibration portion formed along an outer circumferential surface of the shaft portion or the outer cylinder portion; a Z calibration section formed at a tip of the shaft section and having a plane perpendicular to an axial direction of the shaft section; A calibration device comprising:

2. The calibration device according to claim 1 , wherein the outer cylinder portion has a magnet at a bottom portion, and a sloped surface that slopes outwardly relative to a radial direction of the bottom surface is formed at a portion of the bottom portion.

3. 3. The calibration device according to claim 1, wherein the outer tube portion has a thin-walled cylindrical portion that supports the shaft portion, and the fixing portion has a clamper that releasably applies a radial pressing force from an outer periphery of the thin-walled cylindrical portion toward the shaft portion.

4. A machine tool to which the calibration device according to claim 1 can be attached, a spindle for mounting a machining tool, the spindle being capable of mounting a reference tool and the touch probe in place of the machining tool; a table on which a workpiece and the calibration device are mounted; a feed shaft portion for moving the main shaft and the table relatively; A machine tool comprising:

5. 5. The machine tool according to claim 4, wherein the reference tool attached to the spindle has a tip having a spherical shape with the same radius as that of the spherical portion of the contact tip of the touch probe.

6. 6. The machine tool according to claim 4, wherein the reference tool attached to the spindle has a fuse structure that breaks when a load equal to or greater than a predetermined value is applied thereto.

7. A method for calibrating the touch probe using the calibration device according to claim 1, comprising the steps of: placing the calibration device on the machine tool; retaining the shaft portion in a pressed position by the temporary retaining mechanism; a reference tool is attached to a spindle of the machine tool, and the spindle is relatively moved so that a tip end of the reference tool is positioned axially above the Z calibration portion of the shaft portion; Releasing the temporary fastening mechanism and urging the shaft portion toward the reference tool by the urging portion; Fixing the shaft portion abutting against the reference tool with the fixing portion; Obtaining a reference coordinate in an axial direction of the fixed shaft portion; attaching the touch probe to the spindle of the machine tool; Obtaining a reference coordinate in a direction perpendicular to an axial direction of the shaft portion; acquiring calibration values ​​in the axial direction and in a direction perpendicular to the axial direction based on the reference coordinates; A calibration method comprising:

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