JP7696264B2 - tool changer - Google Patents

Description

The present invention relates to a tool changer.

The tool changer for a machine tool disclosed in Patent Document 1 is equipped with a tool magazine having a disk-shaped magazine body with a central axis extending vertically and rotatable about the central axis, and a number of chucks arranged circumferentially on the outer periphery of the magazine body and configured to allow tool holders to be attached and detached. The chucks are inclined at a predetermined angle with respect to the radial direction of the magazine body in the attachment and detachment direction of the tool holders. With this configuration, it is possible to increase the outer diameter of the tool magazine without the tool magazine coming into contact with a column or the like.

JP 2013-208668 A

In order to shorten tool change time, tool holders are sometimes transferred between the spindle and the tool magazine at high speed, and the tool magazine is sometimes rotated at high speed. At this time, the tool holder may become misaligned or tilted relative to the tool magazine. Such poor positioning of the tool holder relative to the tool magazine can cause problems such as improper attachment of the tool holder to the spindle.

In more detail, many processes must be performed to produce a workpiece, and tools must be changed frequently for each workpiece. Tool change time is directly linked to productivity and has a significant impact on the overall production speed and number of pieces produced. Tool change time can sometimes account for more than half of the total production time. Therefore, reducing tool change time is extremely important from the standpoint of productivity.

To shorten tool change time, it is desirable to transfer the tool holder between the spindle and the tool magazine at high speed. However, the gripping part (chuck) of the tool holder in the tool magazine generally has a simple structure and cannot restrict the position of the tool holder.

As a result, tool holders held in the tool magazine are prone to poor posture. Poor posture of the tool holder relative to the tool magazine can cause the tool holder to be mounted improperly on the spindle (for example, poor centering or tilting), which can ultimately cause poor machining accuracy.

The present invention was made in consideration of these points, and its purpose is to more accurately detect poor posture of tool holders held in a tool magazine.

A tool changing device according to the present invention comprises a tool magazine having a tool holder removably held on its outer periphery, and an optical length measuring device arranged outer than the tool magazine, wherein the tool holder has an ellipsoidally shaped groove in a portion facing the outer periphery when held by the tool magazine, and the groove has different radii of curvature in a depth direction in the axial direction and the circumferential direction of the tool magazine, and the optical length measuring device detects a displacement of the inner surface in the depth direction by irradiating light onto an inner surface of the groove in the tool holder held by the tool magazine, and when the tool holder is displaced in at least one of the axial direction and the circumferential direction relative to the tool magazine, the inner surface is displaced in the depth direction.

With this configuration, the groove is formed in an elliptical sphere, so when the tool holder is displaced in at least one of the axial and circumferential directions relative to the tool magazine, i.e., when the tool holder is misaligned relative to the tool magazine, the inner surface of the groove is displaced in the radial direction of the tool magazine, i.e., in the depth direction of the groove.

Here, the tool holder hardly displaces in the depth direction (radial direction) relative to the tool magazine. The tool holder is usually cylindrical with a thick wall around the entire circumference, and is located at the gripping point of the tool magazine, so it is unlikely to undergo thermal deformation or gripping deformation. In addition, the tool magazine is usually disk-shaped. For this reason, the tool holder hardly displaces in the depth direction (radial direction) relative to the tool magazine.

In other words, the optical length measuring device detects the amount of displacement, including the axial and circumferential displacement, of the tool holder relative to the tool magazine by detecting the depth-wise displacement of the inner surface of the groove.

Furthermore, since the radius of curvature of the groove in the depth direction is different between the axial direction and the circumferential direction, the magnitude of the depth direction displacement detected by the optical length measuring device is different between the case where the tool holder is displaced in the axial direction and the case where the tool holder is displaced in the circumferential direction relative to the tool magazine. Specifically, when the tool holder is displaced in the axial direction or the circumferential direction in the direction with the larger radius of curvature in the depth direction, the depth direction displacement is relatively small. On the other hand, when the tool holder is displaced in the axial direction or the circumferential direction in the direction with the smaller radius of curvature in the depth direction, the depth direction displacement is relatively large.

In this way, based on the magnitude of the depth-direction displacement detected by the optical length measuring device, it is possible to estimate whether the tool holder has been displaced axially or circumferentially (or both) relative to the tool magazine.

Therefore, poor posture of the tool holder held in the tool magazine can be detected more accurately.

In one embodiment, the groove has a smaller radius of curvature in the depth direction in the circumferential direction than a radius of curvature in the depth direction in the axial direction.

The circumferential displacement of the tool holder relative to the tool magazine is usually more difficult to detect than the axial displacement of the tool holder relative to the tool magazine. Specifically, if the rotation radius of the tool magazine is small, the rotation of the tool magazine is included in the circumferential displacement, making it difficult to detect the circumferential displacement. Also, if the tool holder is cylindrical, the R-shape of the side surface of the tool holder is included in the circumferential displacement, making it difficult to detect the circumferential displacement.

According to this configuration, the groove is formed so that the radius of curvature in the depth direction in the circumferential direction is small, so that when the tool holder is displaced in the circumferential direction relative to the tool magazine, the displacement in the depth direction detected by the optical length measuring device appears large, making it easier to detect the displacement in the circumferential direction.

In one embodiment, a control unit is provided that determines the displacement direction of the tool holder relative to the tool magazine based on the depth direction displacement.

With this configuration, the control unit can tell the user whether the tool holder has been displaced axially or circumferentially (or both) relative to the tool magazine without the user having to perform manual calculations.

In one embodiment, the control unit has a first model that represents the relationship between the depth direction displacement and the axial and circumferential displacements of the tool holder relative to the tool magazine when the center of the groove portion is used as a reference, and the control unit sets an OK zone and a judgment zone based on the first model, the OK zone is a region where the depth direction displacement includes zero, and the judgment zone is a region where the depth direction displacement is at least larger than the OK zone, and the control unit does not judge the displacement direction when the depth direction displacement is included in the OK zone, and judges the displacement direction when the depth direction displacement is included in the judgment zone.

According to this configuration, the region where the depth direction displacement detected by the optical length measuring device is near zero is set as an OK zone, and the displacement direction is not determined. This makes it possible to eliminate overlapping (interference) portions of the axial and circumferential curvature radii in the displacement direction determination. As the depth direction displacement increases , the difference between the axial and circumferential curvature radii increases, and they no longer interfere with each other (they no longer overlap). The displacement direction is determined by setting as a determination zone a region where the depth direction displacement detected by the optical length measuring device is at least larger than the OK zone, i.e., a region where the axial and circumferential curvature radii do not interfere with each other. This makes it possible to more accurately estimate whether the tool holder has been displaced in the axial or circumferential direction (or in both directions) relative to the tool magazine.

In one embodiment, the control unit further sets an NG zone based on the first model, the NG zone being an area in which the depth direction displacement is greater than the judgment zone, the control unit continues operation of the tool exchange device when the depth direction displacement is included in the OK zone, judges the displacement direction and takes action according to the displacement direction when the depth direction displacement is included in the judgment zone, and stops operation of the tool exchange device when the depth direction displacement is included in the NG zone, the action according to the displacement direction including correcting the attitude of the tool holder relative to the tool magazine.

According to this configuration, when the depth direction displacement detected by the optical length measuring device is included in the OK zone, the displacement (misalignment) of the tool holder relative to the tool magazine is small, so the tool magazine is operated as is. When the depth direction displacement detected by the optical length measuring device is included in the NG zone, the displacement (misalignment) of the tool holder relative to the tool magazine is an amount that can no longer be corrected, so the tool magazine is stopped. When the depth direction displacement detected by the optical length measuring device is included in the judgment zone, the displacement (misalignment) of the tool holder relative to the tool magazine may be an amount that can be corrected, so after the displacement direction of the tool holder relative to the tool magazine is judged, measures are taken according to the judged displacement direction, and in some cases the attitude of the tool holder is corrected. In this way, by setting each zone according to the depth direction displacement, appropriate measures can be taken according to the depth direction displacement detected by the optical length measuring device.

In one embodiment, the control unit determines the displacement direction based on a second model that represents the relationship between the rotation angle of the tool magazine and the depth direction displacement.

According to this configuration, the state of the second model differs depending on whether the tool holder is displaced axially or circumferentially relative to the tool magazine. Therefore, based on the state of the obtained second model, it is possible to easily determine whether the tool holder is displaced axially or circumferentially relative to the tool magazine (or whether it is displaced in both directions).

In one embodiment, the control unit controls the rotation of the tool magazine so that, when it is determined that the displacement direction is the axial direction, the control unit rotates the tool magazine alternately in small increments in the forward and reverse directions, whereas, when it is determined that the displacement direction is the circumferential direction, the control unit controls the rotation of the tool magazine so that the control unit rotates the tool magazine more greatly than the former direction and then stops the tool magazine.

This configuration allows the optimal posture correction (position adjustment) method to be applied depending on the displacement direction of the tool holder relative to the tool magazine.

In one embodiment, the tool magazine is provided with a reference section, the optical length measuring device detects the displacement of the reference section by irradiating light onto the reference section, and the control section zeros the depth direction displacement of the inner surface based on the displacement of the reference section.

With this configuration, the zero point for the depth direction displacement of the inner surface of the groove can be updated each time the optical length measuring device detects the displacement of the reference part as the tool magazine rotates.

The present invention makes it possible to more accurately detect poor posture of tool holders held in a tool magazine.

FIG. 1 is a schematic diagram showing a tool exchange device. FIG. 2 is a view taken along the line II in FIG. 1, showing a tool holder held by a tool magazine. FIG. 3 is a perspective view showing the groove portion in a three-dimensional manner. FIG. 4 is a graph showing the first model, illustrating the relationship between the depth direction displacement and the axial and circumferential displacements. FIG. 5 is a graph showing a second model when the tool holder is displaced in the axial direction relative to the tool magazine, and shows the relationship between the rotation angle of the tool magazine and the displacement in the depth direction. FIG. 6 is a graph showing a second model in the case where the tool holder is displaced in the circumferential direction relative to the tool magazine, and shows the relationship between the rotation angle of the tool magazine and the displacement in the depth direction.

The following describes in detail the embodiments of the present invention with reference to the drawings. The following description of the preferred embodiment is merely exemplary in nature and is in no way intended to limit the present invention, its applications, or its uses.

Figure 1 shows a tool exchange device 1. As shown in Figure 1, the tool exchange device 1 is applied to a machine tool such as an NC milling machine. The tool exchange device 1 includes a motor 2, a tool magazine 10, a laser length measuring device 20 as an optical length measuring device, and a control unit 21. The tool magazine 10 is disk-shaped and rotatable around a central axis C. A tool holder 30 for holding a tool T is detachably held on the outer periphery of the tool magazine 10. Hereinafter, with the tool magazine 10 as a reference, the axial direction of the tool magazine 10 is indicated as Z, the radial direction of the tool magazine 10 is indicated as R, and the circumferential direction of the tool magazine 10 is indicated as θ.

The tool magazine 10 has a magazine body 11 and a chuck 12 as a part for holding a plurality of tools. The magazine body 11 is formed in a disk shape. The magazine body 11 is connected to the drive shaft of the motor 2. The magazine body 11 can rotate around the central axis C by being driven by the motor 2.

The chucks 12 are arranged at equal intervals in the circumferential direction on the outer periphery of the magazine body 11. Each chuck 12 is formed in a roughly U-shape when viewed in the axial direction, and is fixed to the magazine body 11 with its opening facing the outer periphery. A tool holder 30 is removably held by each chuck 12.

Figure 2 is a view taken along the line II in Figure 1, showing a tool holder 30 held by a chuck 12 of a tool magazine 10. As shown in Figure 2, each chuck 12 holds the tool holder 30 by sandwiching it from both sides in the circumferential direction with a pair of arms 13. The tool holder 30 is formed, for example, in a generally cylindrical shape.

A tapered protrusion (claw) 14 is provided on the circumferential inner side of each arm 13. A tapered recess (groove) 32 corresponding to the protrusion 14 is provided on the outer circumferential surface 31 of the tool holder 30. The protrusion 14 and the recess 32 fit together.

As shown in FIG. 1, the tool spindle (main shaft) 3 of the machine tool is arranged parallel to the tool magazine 10. A tool holder 30 is removably attached to the tool spindle 3. The tool spindle 3 machines a workpiece (not shown) by rotating the tool holder 30 holding a tool T.

The tool exchange device 1 transfers the tool holder 30 between the tool magazine 10 and the tool spindle 3. In detail, the tool magazine 10 is rotated by the drive of the motor 2, and the chuck 12 moves to the transfer position P1. Meanwhile, the tool spindle 3 also moves from the processing position (not shown) to the transfer position P1 by an NC axis or the like.

The tool holder 30 is transferred between the tool magazine 10 and the tool spindle 3 at the transfer position P1. In detail, the tool holder 30 attached to the tool spindle 3 is gripped (mounted) in an empty chuck 12, and the tool holder 30 gripped (mounted) in another chuck 12 is released and mounted on the tool spindle 3.

As shown in Figures 1 and 2, the tool holder 30 has a groove 40 on a facing portion (portion) 33 that faces the outer periphery (radially outward) when held by the chuck 12 of the tool magazine 10. The facing portion 33 is finish-machined.

As shown in FIG. 2, the groove 40 is formed in an elliptical sphere shape with its depth aligned with the radial direction of the tool magazine 10. The contour of the opening edge 41 of the groove 40 is an ellipse having a major axis extending in the axial direction and a minor axis extending in the circumferential direction. In detail, the opening edge 41 of the groove 40 is composed of two R50 curves extending in the axial direction and two R12 curves extending in the circumferential direction.

3 shows the groove 40 in a three-dimensional view. The groove 40 has different radii of curvature in the depth direction (radial direction) between the axial direction and the circumferential direction. In detail, the radius of curvature of the groove 40 in the depth direction in the circumferential direction is smaller than the radius of curvature of the groove 40 in the depth direction in the axial direction.

More specifically, the radius of curvature of the groove portion 40 in the depth direction in the axial direction is R50. The radius of curvature of the groove portion 40 in the depth direction in the circumferential direction is R12. The inner surface 42 of the groove portion 40 is deepest in the central portion in the axial direction and shallowest (zero) at both ends. Similarly, the inner surface 42 of the groove portion 40 is deepest in the central portion in the circumferential direction and shallowest (zero) at both ends. Here, the inner surface 42 refers to the spherical surface that constitutes the inner side surface and inner bottom surface of the groove portion 40.

The center O of the groove portion 40 is located at the center of the groove portion 40 in the axial direction and the center of the groove portion 40 in the circumferential direction. In other words, the center O of the groove portion 40 is the intersection of the middle R50 curve and the middle R12 curve. The center O of the groove portion 40 is the innermost part of the groove portion 40.

As shown in FIG. 1, the laser length measuring device 20 is disposed on the outer periphery (radially outward) of the tool magazine 10. As shown in FIGS. 1 and 2, the laser length measuring device 20 irradiates a laser beam (indicated by L) in the radial direction (depth direction) toward the center O of the inner surface 42 of the groove portion 40 in the tool holder 30 held by the chuck 12 of the tool magazine 10.

In detail, as shown in FIG. 1, the tool magazine 10 is rotated by the drive of the motor 2, and the tool holder 30 held by the chuck 12 moves to the length measurement position P2. The facing portion 33 (groove portion 40) of the tool holder 30 faces the laser length measurement device 20 at the length measurement position P2. At the length measurement position P2, the tool holder 30 and the laser length measurement device 20 are spaced apart in the radial direction.

The laser length measuring device 20 detects the depth direction displacement (radial direction displacement) dr, which is the distance from a reference position in the depth direction (radial direction) of the inner surface 42 of the groove portion 40, based on the reflected light when a laser beam is irradiated onto the inner surface 42 of the groove portion 40. The reference position is initially set when the tool exchange device 1 is installed.

As shown in FIG. 1, a reference portion S is provided at the tip of the chuck 12 of the tool magazine 10. The laser length measuring device 20 irradiates laser light onto the reference portion S. The reference portion S is composed of a finished surface, a groove portion, a marker portion, or the like. The reference portion S may be provided on the magazine body 11 instead of the chuck 12. The reference portion S may also be provided on a measuring jig or the like attached to the tool magazine 10.

In detail, the motor 2 drives the tool magazine 10 to rotate, and the reference part S moves to the measurement position P2. The reference part S faces the laser measurement device 20 at the measurement position P2. At the measurement position P2, the direction of separation between the reference part S and the laser measurement device 20 is the radial direction.

The laser length measuring device 20 detects the depth direction displacement (radial direction displacement, not shown) of the reference portion S based on the reflected light when the reference portion S is irradiated with laser light.

The control unit 21 is composed of, for example, a microcomputer and a program. The control unit 21 is connected to the motor 2 and the laser length measuring device 20.

The control unit 21 sets the depth direction displacement (radial displacement) dr of the inner surface 42 of the groove portion 40 to zero based on the depth direction displacement (radial displacement) of the reference portion S. In other words, the control unit 21 updates the reference position (zero point) in the depth direction (radial direction) of the inner surface 42 of the groove portion 40.

Since the groove portion 40 is formed in an elliptical spherical shape, when the tool holder 30 is displaced from the reference position relative to the tool magazine 10 in at least one of the axial and circumferential directions, i.e., when the tool holder 30 is misaligned relative to the tool magazine 10, the inner surface 42 of the groove portion 40 is displaced in the depth direction (radial direction).

Here, the tool holder 30 hardly displaces in the depth direction (radial direction) relative to the tool magazine 10. The tool holder 30 is usually cylindrical with a thick wall thickness all around, and is located at the gripping point (chuck 12) of the tool magazine 10, so it is unlikely to undergo thermal deformation or gripping deformation. In addition, the tool magazine 10 is usually disk-shaped. For this reason, the tool holder 30 hardly displaces in the depth direction (radial direction) relative to the tool magazine 10.

In other words, the laser length measuring device 20 detects the amount of displacement, including the axial displacement dz and the circumferential displacement dθ of the tool holder 30 relative to the tool magazine 10, by detecting the depth displacement (radial displacement) dr of the inner surface 42 of the groove portion 40.

Furthermore, since the radius of curvature of the groove portion 40 in the depth direction is different in the axial and circumferential directions, the magnitude of the depth direction displacement dr detected by the laser length measuring device 20 is different when the tool holder 30 is displaced in the axial direction relative to the tool magazine 10 and when it is displaced in the circumferential direction.

Specifically, when the tool holder 30 is displaced in an axial direction having a large radius of curvature in the depth direction, the depth-direction displacement dr detected by the laser length measuring device 20 is relatively small. On the other hand, when the tool holder 30 is displaced in a circumferential direction having a small radius of curvature in the depth direction, the depth-direction displacement dr detected by the laser length measuring device 20 is relatively large.

The control unit 21 determines the displacement direction (axial or circumferential) of the tool holder 30 relative to the tool magazine 10 based on the depth displacement (radial displacement) dr detected by the laser length measuring device 20.

The control unit 21 has a first model M1. As shown in FIG. 4, the first model M1 represents the relationship between the depth displacement (radial displacement) dr of the inner surface 42 of the groove portion 40 detected by the laser length measuring device 20 and the axial displacement dz and circumferential displacement dθ of the tool holder 30 relative to the tool magazine 10, when the center (innermost part) O of the groove portion 40 is used as a reference. The first model M1 is obtained by transferring the inner surface 42 of the groove portion 40.

As shown in FIG. 4, the first model M1 includes an R50 curve and an R12 curve. The horizontal axis is the axial displacement dz [mm] and the circumferential displacement dθ [mm]. The axial displacement dz corresponds to the R50 curve. The circumferential displacement dθ corresponds to the R12 curve. The vertical axis is the depth displacement dr [μm].

As shown in FIG. 4, the control unit 21 sets an "OK zone," a "Judgment zone," and an "NG zone" according to the depth direction displacement (radial direction displacement) dr based on the first model M1.

The OK zone is a region where the depth direction displacement (radial displacement) dr includes zero. The judgment zone is a region where the depth direction displacement dr is at least greater than the OK zone. The NG zone is a region where the depth direction displacement dr is greater than the judgment zone.

In this embodiment, the depth direction displacement dr is set so that a value less than 3 μm is an OK zone, a value between 3 μm and 25 μm is a judgment zone, and a value greater than or equal to 25 μm is an NG zone.

The control unit 21 also sets an "OK zone," a "judgment (correction) zone," and an "NG zone" according to the axial displacement dz and the circumferential displacement dθ based on the first model M1. In this embodiment, the OK zone is set when the axial displacement dz and the circumferential displacement dθ are less than 0.5 mm, the judgment zone is set when the axial displacement dz and the circumferential displacement dθ are 0.5 mm or more and less than 0.8 mm, and the NG zone is set when the axial displacement dz and the circumferential displacement dθ are 0.8 mm or more.

The control unit 21 has a second model M2. As shown in Figures 5 and 6, the second model M2 represents the relationship between the rotation angle Φ of the tool magazine 10 and the depth direction displacement (radial displacement) dr.

5 shows a case where the tool holder 30 is displaced only in the axial direction relative to the tool magazine 10. The horizontal axis is the rotation angle Φ [°] of the tool magazine 10. The vertical axis is the depth direction displacement dr [μm]. As shown in FIG. 5, in the second model M2, the graph (curve) M2z obtained when the tool holder 30 is displaced only in the axial direction relative to the tool magazine 10 is merely translated in the vertical direction (the depth direction displacement dr is simply changed) compared to the graph (curve) M2o obtained when the tool holder 30 is not displaced at all relative to the tool magazine 10.

Figure 6 shows the case where the tool holder 30 is displaced only in the circumferential direction relative to the tool magazine 10. The horizontal axis is the rotation angle Φ [°] of the tool magazine 10. The vertical axis is the depth direction displacement dr [μm]. As shown in Figure 6, in the second model M2, the graph (curve) M2θ obtained when the tool holder 30 is displaced only in the circumferential direction relative to the tool magazine 10 is simply translated in the horizontal axis direction compared to the graph (curve) M2o obtained when the tool holder 30 is not displaced at all relative to the tool magazine 10.

When the tool holder 30 is displaced in both the axial and circumferential directions relative to the tool magazine 10, a graph is obtained by combining the graphs M2z and M2θ shown in Figures 5 and 6.

The control unit 21 determines the displacement direction (axial or circumferential direction) of the tool holder 30 relative to the tool magazine 10 based on the second model M2.

When the control unit 21 determines that the displacement direction is the axial direction (see FIG. 5), it controls the rotation of the tool magazine 10 (motor 2) to rotate the tool magazine 10 alternately forward and backward in small increments (e.g., about ±2°). This causes a small vibration in the entire system including the tool magazine 10 and tool holder 30, making it easier for the tapered protrusions 14 on the pair of arms 13 of the chuck 12 to fit into the tapered recesses 32 on the outer circumferential surface 31 of the tool holder 30 (see FIG. 2). The tool holder 30 is then adjusted in position in the axial direction.

On the other hand, when the control unit 21 determines that the displacement direction is the circumferential direction (see FIG. 6), it controls the rotation of the tool magazine 10 (motor 2) to rotate the tool magazine 10 by a larger amount (e.g., 90° or more) compared to the former case (when the displacement direction is determined to be the axial direction) and then stops the tool magazine 10. This applies a circumferential inertial force to the tool holder 30, suppressing misalignment in the circumferential direction. If the tool holder 30 is misaligned in the circumferential direction, the tool holder 30 is likely to move to a position that is comfortable for being held in the tool magazine 10. Then, the position of the tool holder 30 is adjusted in the circumferential direction.

When the depth direction displacement (radial displacement) dr is included in the OK zone, that is, when the depth direction displacement dr is less than 3 μm, the axial displacement dz and the circumferential displacement dθ are included in the OK zone of less than 0.5 mm. At this time, the control unit 21 does not judge the displacement direction and continues the operation of the tool exchange device 1. Note that the inventors of the present application have confirmed that when the depth direction displacement (radial displacement) dr is included in the OK zone, there is no problem with the attitude of the tool holder 30 relative to the tool magazine 10.

When the depth direction displacement dr is included in the NG zone, that is, when the depth direction displacement dr is 25 μm or more, the axial displacement dz and the circumferential displacement dθ are included in the NG zone of 0.8 mm or more. At this time, the control unit 21 does not judge the displacement direction and stops the operation of the tool exchange device 1. Specifically, the control unit 21 stops the drive of the motor 2 to stop the rotation of the tool magazine 10.

When the depth direction displacement dr is included in the judgment zone, that is, when the depth direction displacement dr is 3 μm or more and less than 25 μm, the control unit 21 judges the displacement direction and performs a measure according to the judged displacement direction. The measure according to the displacement direction includes correcting the attitude of the tool holder 30 relative to the tool magazine 10.

When the depth direction displacement dr is 3 μm or more and less than 5 μm within the judgment zone, the control unit 21 judges that the displacement direction is axial. Then, the control unit 21 performs axial posture correction (position adjustment) of the tool holder 30 relative to the tool magazine 10 by rotating the tool magazine 10 alternately forward and backward in small increments. The control unit 21 repeats this several times until the depth direction displacement dr detected by the laser length measuring device 20 is included in the OK zone.

If the result of the repetition is that the depth direction displacement dr is within the OK zone, the system transitions to normal operation, whereas if the depth direction displacement dr is not within the OK zone (if the posture cannot be corrected), the system stops the rotation of the tool magazine 10 (stops the operation of the tool changer 1). The number of repetitions can be set arbitrarily.

When the depth direction displacement dr is 5 μm or more and less than 13 μm within the judgment zone, the control unit 21 judges that the displacement direction is the circumferential direction. Then, the control unit 21 performs circumferential posture correction (position adjustment) of the tool holder 30 relative to the tool magazine 10 by rotating the tool magazine 10 by a large amount and then stopping it. The control unit 21 repeats this several times until the depth direction displacement dr detected by the laser length measuring device 20 is included in the OK zone.

When the depth direction displacement dr is 5 μm or more and less than 13 μm, if it is assumed that the error occurs only in the circumferential direction, the maximum installation error is 0.8°, which is within a reasonable range. On the other hand, when the depth direction displacement dr is 5 μm or more and less than 13 μm, if it is assumed that the error occurs only in the axial direction, the maximum installation error is 0.8 mm, which is an unthinkable error amount from the viewpoint of the tapered fit (protrusion 14, recess 32) between the arm 13 of the chuck 12 of the tool magazine 10 and the tool holder 30. In this case, it can be concluded that dirt has adhered to one of the tapered protrusions 14 and recesses 32. At this time, the tool holder 30 is simply sandwiched between the arms 13 of the tool magazine 10, and it is considered that a considerable error occurs in the axial direction (or also in the circumferential direction).

When the depth direction displacement dr is 13 μm or more and less than 25 μm within the judgment zone, the control unit 21 first judges the displacement direction of the tool holder 30 relative to the tool magazine 10 based on the second model M2. Then, when the control unit 21 judges that the displacement direction is the circumferential direction based on the second model M2, it performs a circumferential attitude correction (position adjustment) of the tool holder 30 relative to the tool magazine 10 by rotating the tool magazine 10 significantly and then stopping it. The control unit 21 repeats this several times until the depth direction displacement dr detected by the laser length measuring device 20 is included in the OK zone. On the other hand, when the control unit 21 judges that the displacement direction is the axial direction based on the second model M2, it stops the drive of the motor 2 to stop the rotation of the tool magazine 10 (stops the operation of the tool exchange device 1).

The following method can be used to determine the displacement direction (error direction) more accurately. By rotating the tool magazine 10 by a larger radius of curvature R12 in the circumferential direction of the elliptical groove 40, the elliptical shape of the groove 40 in the circumferential direction can be recognized by a line. This makes it possible to grasp the mounting position of the tool holder 30 relative to the tool magazine 10 more accurately and to specify the error direction (axial or circumferential direction).

As described above, according to this embodiment, the radius of curvature in the depth direction (radial direction) of the groove portion 40 is different between the axial direction and the circumferential direction. Therefore, as shown in FIG. 4, the magnitude of the depth direction displacement (radial displacement) dr detected by the laser length measuring device 20 is different between the case where the tool holder 30 is displaced in the axial direction relative to the tool magazine 10 and the case where the tool holder 30 is displaced in the circumferential direction.

In this way, based on the magnitude of the depth displacement dr detected by the laser length measuring device 20, it is possible to estimate whether the tool holder 30 has been displaced axially or circumferentially (or in both directions) relative to the tool magazine 10.

Therefore, poor posture of the tool holder 30 held in the tool magazine 10 can be detected more accurately.

The circumferential displacement dθ of the tool holder 30 relative to the tool magazine 10 is usually more difficult to detect than the axial displacement dz of the tool holder 30 relative to the tool magazine 10. Specifically, when the rotation radius of the tool magazine 10 is small, the rotation of the tool magazine 10 is included in the circumferential displacement dθ, making it difficult to detect the circumferential displacement dθ. In addition, when the tool holder 30 is cylindrical, the R-shape of the side surface of the tool holder 30 is included in the circumferential displacement dθ, making it difficult to detect the circumferential displacement dθ.

According to this embodiment, the groove 40 is formed so that the radius of curvature in the depth direction in the circumferential direction is small (R12). As a result, when the tool holder 30 is displaced in the circumferential direction with respect to the tool magazine 10, the depth direction displacement dz detected by the laser length measuring device 20 appears large as shown in FIG. 4, so that the circumferential direction displacement dθ can be easily detected.

The control unit 21 allows the user to know whether the tool holder 30 has been displaced axially or circumferentially (or both) relative to the tool magazine 10 without the user having to perform manual calculations.

The region where the depth direction displacement dr detected by the laser length measuring device 20 is near zero is set as an OK zone, and the displacement direction is not judged. This makes it possible to eliminate overlapping (interference) portions of the axial and circumferential curvature radii in the displacement direction judgment. As shown in FIG. 4, the difference between the axial and circumferential curvature radii increases as the depth direction displacement dr increases, and they do not interfere with each other (do not overlap). The region where the depth direction displacement dr detected by the laser length measuring device 20 is at least larger than the OK zone, i.e., the region where the axial and circumferential curvature radii do not interfere with each other, is set as a judgment zone to judge the displacement direction. This makes it possible to more accurately estimate whether the tool holder 30 has been displaced in the axial direction or the circumferential direction (or in both directions) relative to the tool magazine 10.

When the depth direction displacement dr detected by the laser length measuring device 20 is included in the OK zone, the displacement (positional deviation) of the tool holder 30 relative to the tool magazine 10 is small, so the tool exchange device 1 is operated as is. When the depth direction displacement dr detected by the laser length measuring device 20 is included in the NG zone, the displacement (positional deviation) of the tool holder 30 relative to the tool magazine 10 is an amount that can no longer be corrected, so the tool exchange device 1 is stopped. When the depth direction displacement dr detected by the laser length measuring device 20 is included in the judgment zone, the displacement (positional deviation) of the tool holder 30 relative to the tool magazine 10 may be an amount that can be corrected, so after determining the displacement direction of the tool holder 30 relative to the tool magazine 10, measures are taken according to the determined displacement direction, and in some cases, the attitude of the tool holder 30 is corrected. In this way, by setting each zone according to the depth direction displacement dr detected by the laser length measuring device 20, appropriate measures can be taken according to the depth direction displacement dr.

As shown in Figures 5 and 6, the state of the second model M2 differs depending on whether the tool holder 30 is displaced axially or circumferentially relative to the tool magazine 10. Therefore, based on the state of the obtained second model M2, it is easy to know whether the tool holder 30 is displaced axially or circumferentially relative to the tool magazine 10 (or whether it is displaced in both directions).

The optimal posture correction (position adjustment) method can be applied depending on the displacement direction of the tool holder 30 relative to the tool magazine 10.

Each time the laser length measuring device 20 detects the displacement of the reference portion S as the tool magazine 10 rotates, the zero point (reference position) of the depth direction displacement dr of the inner surface 42 of the groove portion 40 can be updated.

The present invention has been described above using preferred embodiments, but these descriptions are not limiting and various modifications are possible.

The determination of the displacement direction of the tool holder 30 relative to the tool magazine 10, or the correction of the attitude of the tool holder 30 by controlling the rotation of the tool magazine 10 may be performed manually by the user, without following a command from the control unit 21.

In this embodiment, the radius of curvature of the groove portion 40 in the depth direction in the axial direction is R50, and the radius of curvature of the groove portion 40 in the depth direction in the circumferential direction is R12, but is not limited thereto. For example, the radius of curvature of the groove portion 40 in the depth direction in the axial direction may be R12, and the radius of curvature of the groove portion 40 in the depth direction in the circumferential direction may be R50. The values of the radii of curvature may be set arbitrarily.

The present invention is extremely useful and has high industrial applicability because it can be applied to tool change devices.

R Depth direction (radial direction)
Z Axial direction θ Circumferential direction dr Depth direction displacement (radial displacement)
dz Axial displacement dθ Circumferential displacement M1 First model M2 Second model R50 Radius of curvature (curve)
R12 Radius of curvature (curve)
Φ Rotation angle OK OK zone NG NG zone JUD Judgment zone L Laser light T Tool S Reference part O Center 1 Tool exchange device 3 Tool spindle 10 Tool magazine 11 Magazine body 12 Chuck 20 Laser length measuring device (optical length measuring device)
21 Control unit 30 Tool holder 33 Facing part (portion)
40 Groove portion 41 Opening edge 42 Inner surface

Claims (8)

a tool magazine having a tool holder detachably held on an outer periphery thereof;
an optical length measuring device disposed on an outer circumferential side of the tool magazine,
the tool holder is provided with an elliptical groove in a portion facing the outer periphery when held by the tool magazine,
The groove portion has a different radius of curvature in a depth direction in an axial direction and a circumferential direction of the tool magazine,
the optical length measuring device detects a displacement of the inner surface in a depth direction by irradiating light onto the inner surface of the groove portion of the tool holder held in the tool magazine,
A tool changing device, wherein when the tool holder is displaced in at least one of the axial direction and the circumferential direction relative to the tool magazine, the inner surface is displaced in the depth direction. 2. The tool changer according to claim 1,
A tool exchange device, wherein the groove portion has a smaller radius of curvature in the depth direction in the circumferential direction than the radius of curvature in the depth direction in the axial direction. 3. The tool exchange device according to claim 1,
a control unit that determines a displacement direction of the tool holder relative to the tool magazine based on the depth direction displacement. 4. The tool exchange device according to claim 3,
the control unit has a first model that represents a relationship between the depth direction displacement and an axial direction displacement and a circumferential direction displacement of the tool holder with respect to the tool magazine when a center of the groove is used as a reference,
The control unit sets an OK zone and a judgment zone based on the first model,
The OK zone is a region in which the depth direction displacement includes zero,
The judgment zone is a region in which the depth direction displacement is at least greater than that of the OK zone,
The control unit does not determine the displacement direction when the depth direction displacement is included in the OK zone, and determines the displacement direction when the depth direction displacement is included in the determination zone. 5. The tool exchange device according to claim 4,
The control unit further sets an NG zone based on the first model,
The NG zone is a region in which the displacement in the depth direction is larger than that of the judgment zone,
The control unit continues operation of the tool exchange device when the depth direction displacement is included in the OK zone, determines the displacement direction and takes action according to the displacement direction when the depth direction displacement is included in the judgment zone, and stops operation of the tool exchange device when the depth direction displacement is included in the NG zone.
A tool changing device, wherein the action according to the displacement direction includes correcting the attitude of the tool holder with respect to the tool magazine. A tool exchange device according to any one of claims 3 to 5,
The control unit determines the displacement direction based on a second model representing the relationship between the rotation angle of the tool magazine and the depth direction displacement. 7. The tool changer according to claim 3,
The control unit controls the rotation of the tool magazine so that, when it is determined that the displacement direction is the axial direction, the control unit rotates the tool magazine alternately in forward and reverse small increments, while, when it is determined that the displacement direction is the circumferential direction, the control unit controls the rotation of the tool magazine so that the control unit rotates the tool magazine more greatly compared to the former and then stops the tool magazine. A tool changer according to any one of claims 3 to 7,
The tool magazine is provided with a reference portion,
the optical length measuring device detects a displacement of the reference portion by irradiating the reference portion with light,
The control unit sets the depth direction displacement of the inner surface to zero based on the displacement of the reference portion.