DE112021003435T5 - Method of measuring a rotary axis center position of a machine tool - Google Patents

Abstract

With a tool (3) attached to a spindle (18) and a detection unit (20) capable of contactlessly detecting the position of the tool (3) placed on a rotary table (13). , the tool (3) and the rotary table (13) are set at predetermined angular positions with respect to a rotation axis (C-axis) of a measurement target. Then, a detecting operation for detecting the position of the tool (3) with respect to the turntable (13) is repeatedly performed at each of the angular positions using the detecting unit (20). Then, a center position of the C-axis is calculated based on the positions of the tool (3) at the respective angular positions detected in the multiple detections.

Description

TECHNICAL AREA

The present invention relates to a method for measuring a rotation axis center position of a machine tool.

BACKGROUND

Machine tools, which include a spindle and a tool attached to the spindle, are configured to machine a workpiece placed on a table using the tool. During the machining process, the tool and the work are three-dimensionally moved in X-axis, Y-axis and Z-axis directions to provide the work with a desired cubic shape.

Some of the machine tools are provided, in addition to the translational axes in X, Y and Z directions, with rotary axes for rotating the tool around the respective translational axes in order to increase the degree of machining freedom. Examples of the additional rotation axes include an A-axis (rotation about the X-axis), B-axis (rotation about the Y-axis), and C-axis (rotation about the Z-axis). An example of a multi-axis control machine tool currently in use is a five-axis control machine tool that includes two (A and C) axes in addition to the three (X, Y, and Z) axes.

For the multi-axis control machine tool described above, in order to improve the machining accuracy, in addition to the positional errors of the translational axes, it is necessary to minimize an angular error of the rotating axes and the positional accuracy of the rotating center. In addition to the above requirements, in order to prevent a reduction in machining accuracy due to the error in the rotation axis center position, it has been proposed to measure the center position of the rotation axis and correct the rotation axis using the measured values as a parameter during the machining process (see Patent Literature 1).

In Patent Literature 1, to measure the center position of the axis of rotation, a reference master in the form of a target ball is attached to the position of a workpiece on a table, and a touch signal probe is attached to the position of a tool on a spindle. Then, the axis of rotation to be measured is set at a plurality of angles and the touch signal probe is brought into contact with the target sphere at each of the angular positions to measure the center position of the target sphere, wherein the center position of the axis of rotation is calculated based on the measurements at the plurality of angular positions.

In particular, Patent Literature 1 discloses that in order to measure the center position of the rotation axis with high accuracy, even in a machine tool whose translational axes are movable only in a limited range due to structural limitations of the machine tool, the touching operations between the touch signal probe and the target sphere at the multiple angular positions of the rotation axis performed only within the movable range of the translational axes, the touch operation is not performed in the range whose movement is restricted, and the center position of the rotational axis is measured by calculations.

Meanwhile, a method of detecting a blade edge position capable of measuring error amounts in all of the X, Y, and Z directions with a single measuring device has been developed even when adjustable ranges of rotation axes (fourth and fifth axes) are limited due to Interference between the tool to be measured and the measuring device is greatly restricted (Patent Literature 2).

Patent Literature 2 discloses that error amounts for positioning a blade edge of a tool in X, Y, and Z directions are calculated based on error amounts in two directions from the tool center point obtained by measuring the bottom point of the tool in a rotation axis of a rotary table and two or more points can be obtained on an outer periphery of the tool in a plane perpendicular to the axis of rotation of the rotary table.

CITATION LIST

PATENT LITERATURE(S)

• patent literature 1 JP 2019-152574 A
• patent literature 2 JP 2020-28922 A

SUMMARY OF THE INVENTION PROBLEM(S) INTENDED TO BE SOLVED BY THE INVENTION

According to the above-described measurement method disclosed in Patent Literature 1, the center position of the rotation axis can be measured with high accuracy even in a machine tool with a limited range of movement of the translation axes.

However, the measuring method of Patent Literature 1 requires that the touch signal probe is attached to the position of a blade on the spindle in order to detect the position of the target ball.

The state of the machine tool during the measurement is thus different from the state of the machine tool during an actual machining process (i.e. with a tool attached to the spindle), with the measured center position of the axis of rotation deviating from the center position during the machining process, which limits the measurement accuracy.

In addition, the measurement method disclosed in Patent Literature 1 is not applicable to a machine tool whose spindle is not configured to accommodate a touch signal probe.

In contrast, Patent Literature 2, which discloses some methods for calculating the error amounts of the tool center point in two directions, is applicable only to a specific type of tool (e.g., ball end mill) that has an end suitable to be treated as a "true circle". and is not applicable to tools with other tip shapes, making it difficult to measure the center position with high accuracy. It is therefore desired that the center position of the axis of rotation of tools with various tip shapes can be measured highly accurately by a simple calculation.

An object of the invention is to provide a rotating axis center position measuring method for a machine tool capable of measuring a rotating axis center position highly accurately by a simple calculation without using a touch signal probe.

Another object of the invention is to provide a rotating axis center position measuring method for a machine tool capable of highly accurately measuring a rotating axis center position of tools having various tip shapes by a simple calculation.

MEANS TO SOLVE THE PROBLEM(S)

A method of measuring a rotational axis center position of a machine tool according to an aspect of the invention includes: attaching a tool to a spindle; Placing a detection unit that is set up to detect a position of the tool without contact on a table; repeatedly performing detection operations for adjusting the tool and the table at predetermined angular positions with respect to a rotation axis of a measurement target and detecting a position of the tool with respect to the table at each of the angular positions using the detection unit; and calculating the rotation axis center position based on the positions of the tool at the angular positions detected in the plurality of detections.

In accordance with the above aspect of the invention, the detection operations using the non-contact detection unit are repeated multiple times to achieve highly accurate measurement of the center position of the rotation axis through geometric calculation based on the positions of the tool at the respective angular positions.

During the measurement, the tool used for the actual machining can be attached to the spindle of the machine tool, wherein the spindle can be optionally rotated and raised in temperature immediately before the measurement, enabling measurement under substantially the same conditions as during the actual machining process is made possible. Further, the invention is widely applicable to a machine tool incapable of attaching a touch signal probe to the spindle.

Accordingly, the above aspect of the invention can provide a rotational axis center position measuring method for a machine tool capable of measuring a center position of a rotational axis highly accurately by a simple calculation without using a touch signal probe.

It should be noted that in the above aspect of the invention, when the position and the orientation of the detection unit with respect to the table have been determined highly accurately, the rotation center of the rotation axis can be calculated with a smaller number of measurements. However, the tip position of the tool can be narrowed down so that it can be determined highly accurately by a geometric calculation by detecting the position of the tool at respective angular positions through multiple detections, even if the position and orientation of the detection unit with respect to the table are not be measured with high precision.

In the method for measuring a rotating axis center position of a machine tool according to the above aspect of the invention, it is preferable that the detecting unit is used thereto is aimed at detecting in a non-contact manner that a tip of the tool is at a certain position in the detecting unit, and in the detecting operations after the spindle and the table are relatively moved to adjust the tool and the table to the predetermined angular positions, and adjusting the relative position of the spindle and the table so that the tool is positioned at the specific position of the detection unit at each of the angular positions, detecting the position of the tool with respect to the table at each of the angular positions based on the relative position of the spindle and the table becomes.

In the above aspect of the invention, when the position of the tool relative to the table is to be detected in the detecting process using the detecting unit, the position of the tool is optionally detected by the detecting unit, or alternatively, the detecting unit is optionally used as a positioning device of the tool and controller position data is optionally received from a controller of the machine tool. In particular, when the machine tool is operated under the control of the controller to move the spindle to locate the tool at a specific position of the detection unit, the position of the tool can be obtained by referencing the position data of the spindle in the controller of the machine tool. An example of the specific position is the center position of a tool detection area of the detection unit.

In the method for measuring a rotation axis center position of a machine tool in accordance with the above aspect of the invention, it is preferable that: the detection unit is configured to detect the positions of the tool in a radial direction of the table; the tool and the table are set at four angular positions including two angular positions opposed in a first direction transverse to the axis of rotation and two angular positions opposed to each other in a second direction crossing the first direction transverse to the axis of rotation, the detecting operations are performed on the respective angular positions to detect the positions of the tool in the radial direction of the table; and a first straight line passing a midpoint of a line segment connecting the positions of the tool detected at the two angular positions facing each other in the first direction and crossing the first direction, and a second straight line the one center of a line segment connecting the positions of the tool detected at the two angular positions facing each other in the second direction and crossing the second direction are calculated, taking an intersection of the first straight line and the second straight line as the center position of the axis of rotation is determined.

An example of the detection unit capable of detecting the position of the tool in the radial direction of the table in the above aspect of the invention is an image sensor configured to detect a lateral image of the tool to measure the position of the tool in the image with the image sensor oriented in a circumferential direction of the table.

An example of the four facing angular positions transverse to the axis of rotation are the 0 degree position and the 180 degree position as the two angular positions facing in the first direction, and the 90 degree position and the 270 degree position as the two angular positions facing in the second direction.

In accordance with the above aspect of the invention, the center position within the estimated range, which cannot be determined in the detections at the angular positions at 0 and 180 degrees, can be narrowed down by the position of the tool during the detections at the angular positions at 90 and 270 degrees be used to determine the exact center of the axis of rotation. In other words, the center position of the axis of rotation can be measured with high accuracy through the detection operations at the total of four angular positions.

In the method for measuring a rotation axis center position of a machine tool in accordance with the above aspect of the invention, it is preferable that: the detection unit is configured to detect the positions of the tool along a surface of the table; the tool and the table are set in two angular positions opposite each other transversely to the axis of rotation, the detection operations being carried out at the respective angular positions in order to detect the positions of the tool along the face of the table; and a center point of a line segment connecting the positions of the tool at the two detections is calculated, the center point being determined as the center position of the axis of rotation.

An example of the detection unit configured to detect the position of the tool along the surface of the table in the above aspect of the invention is a detection unit configured to detect the position of the tool in the radial direction and in the circumferential direction of the table, and which is in particular an image sensor system having an auto-focus function and which is placed on the table and aligned in the circumferential direction of the table, the image sensor system being arranged to determine the position of the tool in a lateral image of the tool as the radial position and the position of the tool in the depth direction in the image captured by the auto focus function as the circumferential position of the tool.

An example of the two angular positions that are opposite across the axis of rotation is the 0 degree position and the 180 degree position of the table.

In accordance with the above aspect of the invention, the central position of the axis of rotation can be measured highly accurately by a simple operation in terms of the detection operations at the two angular positions.

In the method for measuring a rotation axis center position of a machine tool in accordance with the above aspect of the invention, it is preferable that: the detection unit is configured to detect the positions of the tool in a radial direction of the table; the tool and the table are set at a plurality of angular positions within a predetermined angular range around the axis of rotation, the detecting operations being performed at the respective angular positions to detect the positions of the tool in the radial direction of the table; and the positions of the tool detected in the plurality of detections are plotted to calculate the center position of the axis of rotation by an approximate calculation.

According to the above aspect of the invention, even if the detecting operations cannot be performed in a part of the angular range around the axis of rotation due to structural limitations of the machine tool, the center position can be obtained by repeatedly performing the detecting operations in a limited angular range (except for the part of the above angular range) are determined to plot candidate positions of the rotation axis center position in an arc shape, for example, and apply an approximation calculation (e.g., least squares method) to the plotted candidate positions.

In the method for measuring a rotation axis center position of a machine tool in accordance with the above aspect of the invention, it is preferable that the detection unit includes a stopper to be fixed to the table.

In the above aspect of the invention, it is required that the detection unit placed on the table does not shift from the position placed on the table during the detection operations on the angular positions. If a surface of the table faces upwards, it is only necessary that the movement of the sensing unit be restricted only by being placed against the surface (i.e. by a frictional force). When the surface of the table is directed in a direction other than the upward direction, it is preferable that an additional stopper is provided to be fixed to the table so that the detection unit does not fall off the table.

Examples of the stopper, which is preferably easy to attach/detach, include an adhesion stopper using a magnet, an adhesion stopper (e.g., adhesive sheet and adhesive), and a mechanical stopper (e.g., clamp). The detection unit, which is of a non-contact type, is basically not moved by coming into contact with the tool. Accordingly, it is not necessary to rigidly fix the detection unit to the table.

In the method for measuring a rotation axis center position of a machine tool according to the above aspect of the invention, it is preferable that the detection unit includes an illuminator configured to emit a parallel beam and an image pickup device configured to illuminate the parallel beam and detecting a tip position of the tool positioned in the parallel beam based on an image captured by the imager.

Examples of the illumination suitably usable in the above aspect of the invention include an illumination having a point light source and a telecentric lens to form the parallel beam, an illumination having a linearly arranged light source to form the parallel beam , and an illuminator configured to collimate the light beam to form a pseudo parallel beam.

In the above aspect of the invention, the image pickup device is preferably an image detector (e.g., a CCD (Charge Coupled Device) camera) capable of outputting a captured image in the form of data for image processing.

According to the above aspect of the invention, to detect the tip position of the tool positioned in the parallel beam in the image captured by the imager, software is optionally used that is set up to apply known image processing to the image captured by the imager to remove the shadow of the im To detect parallel beam positioned tool, the center position is calculated by edge detection based on the contour of the tip of the tool to determine the tip position of the tool.

In accordance with the above aspect of the invention, the tip position of the tool can be detected highly accurately by the optical detection in a non-contact manner.

Furthermore, for detecting the position, it is only necessary that the tip of the tool is positioned in the parallel beam between the illuminating device and the image pickup device, thereby achieving a simple detecting operation.

In the method for measuring a rotation axis center position of a machine tool according to the above aspect of the invention, it is preferable that the image is captured by the imager while the tool is rotated with respect to the imager, a contour of the tool is captured from the image, wherein the center axis of the tool is detected based on a symmetry of the contour, and an intersection point of the center axis and the contour is determined as a tip position of the tool.

According to the above aspect of the invention, the center axis of the tool can be detected using line symmetry of the contour of the rotating tool, and the tip position of the tool can be determined as the intersection of the detected center axis and the contour of the tool. At this time, the tip shape of the tool is not limited, and the tip position can be determined on tools with different tip shapes. Furthermore, geometric arithmetic processing on the image of the tool is required only for determining the tip position, so that the tip position of the tool and/or the center position of the axis of rotation can be measured highly accurately by a simple calculation.

In the method for measuring a rotating axis center position of a machine tool according to the above aspect of the invention, it is preferable that, in a case where the intersection point of the center axis and the contour is determined as the tip position of the tool, a pair of parallel lines on respective sides of the center axis in a predetermined distance, defining an auxiliary contour line passing an intersection of the pair of parallel lines and the contour and being perpendicular to the central axis, and determining the intersection of the central axis and the auxiliary contour line as the tip position of the tool.

In accordance with the above aspect of the invention, the tip position of the tool can be determined from the center point even if the shape of the contour of the tip portion of the tool becomes blurred when the tool is rotated (e.g. tool with multiple projections on the tip and tool with an eccentric tip). , by defining the auxiliary contour line. Accordingly, the tip position and/or the center position of the axis of rotation of the tool can be measured very accurately by simple calculation for the tool having various tip shapes.

In the method for measuring a rotational axis center position of a machine tool according to the above aspect of the invention, it is preferable that a plurality of transverse lines crossing the contour are defined in an extending direction of the tool, two intersections of each transverse line with the contour and a midpoint of the two intersections for each of the transverse lines, and a straight line passing through the center of each of the transverse lines is determined as the center axis of the tool.

In accordance with the above aspect of the invention, the accurate center axis (rotational symmetry axis) of the tool can be detected using the extending direction of the tool (orientation of the tool, approximate axial direction). At this time, the tip position and/or the center position of the rotating axis of the tool can be measured highly accurately and easily by geometric arithmetic processing using the plurality of transverse lines.

In the method for measuring a rotational axis center position of a machine tool according to the above aspect of the invention, it is preferable that a shape of one side of the contour with respect to the direction of extension of the tool is detected as a reference pattern, the contour being a symmetry pattern whose shape with a inverted shape of the reference pattern is detected, with a straight line passing through a center point of the reference pattern and the symmetry pattern being determined as a center axis of the tool.

In accordance with the above aspect of the invention, the accurate center axis (rotational symmetry axis) of the tool can be detected using the extending direction of the tool (orientation of the tool, approximate axial direction). At this time, the tip position and/or the center position of the axis of rotation of the tool can be measured highly accurately and easily by the pattern recognition on the image.

According to the above aspect of the invention, a method of measuring a rotating axis center position for a machine tool capable of measuring a center position of a rotating axis highly accurately by a simple calculation without using a touch signal probe can be provided. Furthermore, a rotational axis center position measurement method for a machine tool capable of highly accurately measuring a rotational axis center position of tools having various tip shapes by a simple calculation can be provided.

character list

• 1 14 is a perspective view showing a machine tool in accordance with a first exemplary embodiment of the invention.
• 2 14 is a perspective view showing a detection unit of the first exemplary embodiment.
• 3 Fig. 12 is a schematic diagram showing the detection unit of the first exemplary embodiment.
• 4 14 is a perspective view showing a detection process of the first exemplary embodiment.
• 5 12 is a schematic diagram showing a tool tip during the detection process of the first exemplary embodiment.
• 6 Fig. 12 is a schematic diagram showing the detection process of the first exemplary embodiment.
• 7A 12 is a schematic diagram showing a C-axis position measuring process of the first exemplary embodiment.
• 7B 12 is another schematic diagram showing the C-axis position measuring process of the first exemplary embodiment.
• 7C 12 is another schematic diagram showing the C-axis position measuring process of the first exemplary embodiment.
• 8A 12 is another schematic diagram illustrating the C-axis position measuring process of the first exemplary embodiment.
• 8B 12 is another schematic diagram showing the C-axis position measuring process of the first exemplary embodiment.
• 8C 12 is another schematic diagram showing the C-axis position measuring process of the first exemplary embodiment.
• 9 12 is another schematic diagram showing the C-axis position measuring process of the first exemplary embodiment.
• 10A 12 is a schematic diagram showing a C-axis position measuring process of a second exemplary embodiment of the invention.
• 10B 12 is another schematic diagram showing the C-axis position measuring process of the second exemplary embodiment of the invention.
• 10C 12 is another schematic diagram showing the C-axis position measuring process of the second exemplary embodiment of the invention.
• 11A 12 is a schematic diagram showing a C-axis position measuring process of a third exemplary embodiment of the invention.
• 11B 12 is another schematic diagram showing the C-axis position measuring process of the third exemplary embodiment of the invention.
• 11C 12 is another schematic diagram showing the C-axis position measuring process of the third exemplary embodiment of the invention.
• 12A 12 is another schematic diagram showing the C-axis position measuring process of the third exemplary embodiment.
• 12B 12 is another schematic diagram showing the C-axis position measuring process of the third exemplary embodiment.
• 12C Fig. 12 is another schematic showing the C-axis position measurement process of the third exemplary embodiment.
• 13 Fig. 12 is a schematic diagram showing a modification of the first to third exemplary embodiments.
• 14 12 is a schematic diagram showing an A-axis position measuring process of a fourth exemplary embodiment of the invention.
• 15A 12 is another schematic diagram showing the A-axis position measuring process of the fourth exemplary embodiment.
• 15B 12 is another schematic diagram showing the A-axis position measuring process of the fourth exemplary embodiment.
• 16 12 is another schematic diagram showing the A-axis position measuring process of the fourth exemplary embodiment.
• 17 12 is a schematic diagram showing an A-axis position measuring process of a fifth exemplary embodiment of the invention.
• 18 12 is another schematic diagram showing the A-axis position measuring process of the fifth exemplary embodiment.
• 19A 12 is another schematic diagram showing the A-axis position measuring process of the fifth exemplary embodiment.
• 19B 12 is another schematic diagram showing the A-axis position measuring process of the fifth exemplary embodiment.
• 20 12 is another schematic diagram showing the A-axis position measuring process of the fifth exemplary embodiment.
• 21A 12 is a schematic diagram showing an A-axis position measuring process of a sixth exemplary embodiment of the invention.
• 21B 12 is another schematic diagram showing the A-axis position measuring process of the sixth exemplary embodiment of the invention.
• 21C 12 is another schematic diagram showing the A-axis position measuring process of the sixth exemplary embodiment of the invention.
• 22 12 is a schematic diagram showing a modification of the A-axis position measuring process of the sixth exemplary embodiment.
• 23A 12 is a schematic diagram showing a modification of the A-axis position measuring process of the sixth exemplary embodiment.
• 23B 12 is another schematic diagram showing the modification of the A-axis position measuring process of the sixth exemplary embodiment.
• 23C 12 is another schematic diagram showing the modification of the A-axis position measuring process of the sixth exemplary embodiment.
• 24A 12 is a schematic diagram showing a method for detecting a tool tip position of a seventh exemplary embodiment.
• 24B 14 is another schematic diagram showing the method for detecting the tool tip position of the seventh exemplary embodiment.
• 24C 14 is another schematic diagram showing the method for detecting the tool tip position of the seventh exemplary embodiment.
• 25A 12 is a diagram showing a position detecting method for a tool tip with different orientation of the seventh exemplary embodiment.
• 25B 12 is another schematic diagram showing the position detecting method for a tool tip with different orientation of the seventh exemplary embodiment.
• 26A 12 is a schematic diagram showing a tool tip position detection method of an eighth exemplary embodiment.
• 26B 12 is another schematic diagram showing the method for detecting the tool tip position of the eighth exemplary embodiment.
• 27A 12 is a schematic diagram showing a shape and an image of a tool tip of a ninth exemplary embodiment.
• 27B 12 is another schematic diagram showing the shape and image of the tool tip of the ninth exemplary embodiment.
• 27C 12 is another schematic diagram showing the shape and image of the tool tip of the ninth exemplary embodiment.
• 28A 12 is a schematic diagram showing a method for detecting a tool tip position of the ninth exemplary embodiment.
• 28B 12 is another schematic diagram showing the method for detecting the tool tip position of the ninth exemplary embodiment.

DESCRIPTION OF THE EMBODIMENT(S)

First exemplary embodiment

As in 1 1, a machine tool 1 includes a bed 11, a movable table 12 and a turntable 13, the movable table and the turntable 12, 13 being provided on an upper side of the bed 11. As shown in FIG.

The movable table 12 supported by the bed 11 in a manner to be movable along the upper side of the bed 11 and moved by an X-axis moving mechanism (not shown) provided on the bed 11 is capable of being arranged at a predetermined position in an X-axis direction.

The turntable 13, which is provided on an upper side of the movable table 12 in a rotatable manner, is rotatable by a C-axis rotating mechanism (not shown) provided in the movable table 12 and is capable of doing so a predetermined angular position about a C-axis.

A workpiece 2 (machining target) is fixed to an upper side of the rotary table 13 .

The machine tool 1 includes a portal-shaped column 14 on the upper side of the bed 11 .

The column 14 is a portal-shaped member that extends across a movement path of the movable table 12 in the X-axis direction. A spindle head 17 is supported on the column 14 by a saddle 15 and a slider 16 .

The saddle 15, which is movably supported along a horizontal beam of the column 14, is movable by a Y-axis moving mechanism (not shown) provided on the column 14 to be able to move at a predetermined position in the Y-axis direction to be arranged.

The slider 16, which is supported movably up and down along a vertical surface of the saddle 15, is movable by a Z-axis moving mechanism (not shown) provided on the saddle 15 to move to a predetermined position in the Z -Axis direction to be arranged.

The spindle head 17, which is supported by a lower surface of the slider 16 in a rotatable manner, is rotatable by an A-axis rotating mechanism (not shown) provided on the slider 16 to rotate at a predetermined angular position about the A -axis to be arranged.

A spindle 18 is rotatably supported by the spindle head 17 . A tool 3 is attached to one end of the spindle 18 .

The spindle 18 is rotatable by a motor provided in the spindle head 17 to rotate the tool 3 at a predetermined rotational speed and torque required for machining the workpiece 2 .

The machine tool 1 is configured to perform various machining operations on the workpiece 2 by controlling a five-axis operation involving C-axis rotation of the rotary table 13 and A-axis rotation of the spindle head 17 in addition to the X-axis movement, Y-axis movement described above and Z-axis movement caused by the movable table 12, the saddle 15 and the slider 16, respectively. In order to control these processes, the machine tool 1 is connected to a CNC (Computerized Numerical Control) controller 9 .

The rotation axis center position of the C-axis of the rotary table 13 of the machine tool 1 is measured as follows.

As in 2 1, in the present exemplary embodiment, for measuring a C-axis center position of the machine tool 1, a detection unit 20 is placed on the rotary table 13.

As in 3 As shown, the detection unit 20, which includes a housing 21 provided with legs 22 at its respective ends, is detachably attached to the surface of the turntable 13 by the legs 22. As shown in FIG. The legs 22, each containing a stopper in the form of, for example, adhesives, magnets or suction cups are attached to the surface of the Turntable 13 fixed so that they can not be moved.

The housing 21 includes an opening 23 opened upward at a central portion thereof. A first side and a second side opposite the first side across the opening 23 are defined within the housing 21, with an illuminator 24 provided on the first side, a telecentric lens 25, a CCD camera 26 (image pickup) and an arithmetic section 27 are provided on the second side.

The illumination 24 is set up to emit a parallel beam 28 through the opening 23 in the direction of the telecentric lens 25 .

The parallel beam 28 is condensed by the telecentric lens 25 to be imaged by the CCD camera 26. FIG.

The CCD camera 26 (image recorder) is set up to capture a transverse image of the parallel beam 28 from the condensed light received. When an acquisition target 29 is positioned in the aperture 23, a portion of the collimated beam 28 is blocked to form a shadow 281. FIG.

The arithmetic section 27, which is designed to process the image captured by the CCD camera 26 and measure a width and height of the shadow 281 seen in the captured image, can calculate the width and height of the capture target 29 record without contact.

As in 4 As shown, when a tip of the tool 3 is inserted into the opening 23 of the detection unit 20 described above, the position of the tip of the tool 3 positioned in the parallel beam 28 in a shape of the detection target 29 can be detected.

The detection unit 20 is placed so that the parallel beam 28 is aligned in a circumferential direction of the turntable 13 (i.e., a direction perpendicular to a radial direction of the turntable 13). In other words, the detection unit 20 is placed so that the illuminator 24 and the CCD camera 26 face each other along the circumferential direction of the turntable 13 .

The position of the detection unit 20, which is only necessary to face away from the center of the turntable 13, is not necessarily measured accurately. Furthermore, the detection unit 20 does not necessarily have to be aligned so that the parallel beam 28 is accurately aligned with the circumferential direction of the rotary table 13 . Because even if there is an inaccurate component(s), the inaccurate component is canceled at opposite positions (an angular position A0 and angular position A180, and an angular position A90 and angular position A270) in the calculation described later.

When the tool 3 is inserted into the detection unit 20, the position of the tool 3 is adjusted so that the tip position of the tool 3 is at the center of the image captured by the CCD camera 26 (an in 5 captured image shown 261).

As in 5 shown, the shadow 281 of the tip of the tool 3 appears in the captured image 261 of the CCD camera 26.

Based on a contour 282 of the shadow 281 in the captured image 261, coordinates (Tv, Th) of a tip position 283 of the tool 3 can be calculated accurately.

The vertical coordinate Tv of the coordinates (Tv, Th) measured in the captured image 261 corresponds to the Z-axis coordinate of the machine tool 1. The horizontal coordinate Th showing a radial position Rc (a distance in the radial direction) of the tool 3 with respect to the On the other hand, the center point of the turntable 13 can be projected onto the X-axis coordinate and the Y-axis coordinate of the machine tool 1 depending on the angular position of the turntable 13 . For example, if the turntable 13 is in the in 7A As shown, the captured image 261 crosses the X-axis of the machine tool 1 with the coordinate Th being read as the coordinate Ty of the Y-axis of the machine tool 1 . When the turntable 13 is in an in 8A As shown, the captured image 261 crosses the Y-axis of the machine tool 1 with the coordinate Th being read as a coordinate Tx of the X-axis of the machine tool 1 .

In order to calculate the coordinates (Tv, Th) of the tip position 283 of the tool 3, the tip position of the tool 3 is optionally detected by the arithmetic section 27 through image processing of the captured image 261, or alternatively by using the detection unit 20 as a positioning device of the tool 3 for determining the tip position of the tool 3 by obtaining the position data of the machine tool 1. The detection process of the tip position of the tool 3 at this time, which is optionally executed by the arithmetic section 27 provided in the detection unit 20, is alternatively performed by the controller 9 of the machine tool 1 together with the processing of the recorded th image 261 after the image is captured by the CCD camera 26 in the capturing unit 20 .

As in 6 1, the controller 9 of the machine tool 1 includes a motion controller 91 configured to control the above-described motion in the respective axis directions, and a tool position detector 92 configured to perform image processing on the captured image 261 captured by of the detecting unit 20 for detecting the tip position of the tool 3 has been obtained.

In the detection process, the machine tool 1 is operated under the control of the movement controller 91 to move the spindle 18 so that the tool 3 is inserted into the opening 23 of the detection unit 20, with a relative position between the spindle 18 and the rotary table 13 being adjusted is that the tip of the tool 3 is located at a specific position of the detection unit 20 . In this state, the tool position detector 92 receives the position data of the spindle 18 (Z-axis coordinate, X-axis coordinate and Y-axis coordinate of the machine tool 1) from the motion controller 91 to calculate the coordinates Tv, Th in the captured image 261 so as to calculate the To detect tip position of the tool 3.

An example of the specific position is the center position of the opening 23 that defines a tool detection area of the detection unit 20 . Optionally, in order to locate the tip of the tool 3 at the specific position, a mark or the like indicating the specific position is displayed in the captured image 261 of the CCD camera 26 . Alternatively, the specific position, which is optionally defined at the center position of the captured image 261 of the CCD camera 26, is determined only by visual inspection. Because even if the determined position is inaccurate, inaccurate components are canceled in the calculation at opposite positions described later (an angular position A0 and angular position A180, and an angular position A90 and angular position A270).

In the present exemplary embodiment, the center position of the C-axis of the machine tool 1 is measured using the detection unit 20 described above as follows.

As in 7A 1, the detection unit 20 is placed at a position away from the center of the turntable 13, and the turntable 13 is first set at the angular position A0.

The optical axis of the CCD camera 26 is aligned with the X-axis of the machine tool 1 at the angular position A0 of the rotary table 13 . However, it should be noted that the angular position A0 is determined at a desired angle.

After the detection unit 20 is placed, the spindle 18 (see 1 ) is lowered from above the turntable 13 to insert the tool 3 into the opening 23 of the detection unit 20. Then, the position P0 (Tx0, Ty0) of the tool 3 at the angular position A0 is picked up by the detection unit 20 .

The tool 3 is then lifted to be removed by the detection unit 20 . Then, with the detection unit 20 placed, the rotary table 13 is rotated 180 degrees from the angular position A0 to be set at the angular position A180 opposite to the angular position A0 across the C-axis in the first direction D1.

As in 7B 1, the tool 3 is reinserted into the detection unit 20 with the turntable 13 set at the angular position A180. Then, the tip position P180 (Tx180, Ty180) of the tool 3 at the angular position A180 is picked up by the detection unit 20. FIG.

As in 7C 1, when the positions P0, P180 of the tool 3 at the respective angular positions A0 and A180 are determined, the arithmetic section 27 calculates a first straight line L1 passing through the center position of the C axis and crossing the first direction D1. Specifically, the position P0 of the tool 3 at the angular position A0 and the tip position P180 of the tool 3 at the angular position A180 are connected with a line segment L01, with a straight line passing through the center of the line segment L01 and crossing the first direction D1 as the first straight line L1 is defined.

After determining the first straight line L1 by the in the 7A until 7C detection operations shown, a second straight line L2 is calculated in accordance with similar steps.

As in 8A As shown, the tool 3 is inserted into the opening 23 of the detection unit 20 with the detection unit 20 and the rotary table 13 set at an angular position A90 (ie, an angular position rotated 90 degrees from the angular position A0). Then the tip position becomes P90 (Tx90, Ty90) of the tool 3 at the angle position A90 recorded by the detection unit 20.

After the detection unit 20 and the rotary table 13 are positioned at an angular position A270 (opposite the angular position A90 across the C-axis in a second direction D2 (a direction crossing the first direction D1)) through similar operations as in FIG 8B are set, the tip position P270 (Tx270, Ty270) of the tool 3 at the angular position A270 is detected by the detecting unit 20.

As in 8C 1, after the tip positions P90, P270 of the tool 3 at the angular positions A90, A270 are determined, the second straight line L2 passing through the center position of the C axis and crossing the second direction D2 is calculated by the arithmetic section 27 . Specifically, the tip position P90 of the tool 3 at the angular position A90 and the tip position P270 of the tool 3 at the angular position A270 are connected with a line segment L02, with a straight line passing through the center of the line segment L02 and crossing the second direction D2 as the second straight line L2 is defined.

As in 9 1, after determining the first straight line L1 and the second straight line L2, an intersection point Pc of the first straight line L1 and the second straight line L2 is calculated by the arithmetic section 27. The possible range in which the center position of the C-axis can exist is thus limited to a single point (ie, the intersection point Pc), whereby the precise center position of the C-axis of the machine tool 1 is measured.

According to the present exemplary embodiment, the following advantages can be obtained.

In the present exemplary embodiment, after the tool 3 is attached to the spindle 18 and the detecting unit 20 capable of detecting the position of the tool 3 in a non-contact manner is placed on the rotary table 13, the tool 3 and the Turntable 13 set at predetermined angular positions (A0, A90, A180, A270) with respect to the C-axis of the measurement target. Then, the detecting operation for detecting the positions (P0, P90, P180, P270) of the tool 3 with respect to the turntable 13 is repeatedly performed by the detecting unit 20 at each of the angular positions. Then, the center position (Pc) of the C-axis is calculated based on the positions of the tool 3 at the respective angular positions detected by the four detections.

According to the present exemplary embodiment, the detection operations are repeated four times using the non-contact detection unit 20 to achieve highly accurate measurement of the center position (Pc) of the C-axis through geometric calculation based on the positions of the tool 3 at the respective angular positions.

During the measurement, the tool 3 for the actual machining can be attached to the spindle 18 of the machine tool 1, the spindle 18 being optionally rotated and raised in temperature immediately before the measurement in order to carry out a measurement under substantially the same conditions as during the allow the actual editing process. Further, the invention is widely applicable to the machine tool 1 in which a touch signal probe cannot be attached to the spindle 18.

Accordingly, the present exemplary embodiment enables highly accurate measurement of the center position of the C-axis by a simple calculation without using a touch signal probe.

In the present exemplary embodiment: specifically, the detection unit 20 capable of detecting the radial position of the rotary table 13 of the tool 3 is used; the tool 3 and the turntable 13 are set to four angular positions, which are the two angular positions A0, A180, which are opposite to each other in the first direction D1 transverse to the C-axis, and the two angular positions A90, A270, which are opposite to each other in the second direction D2 , which crosses the first direction D1 transverse to the C-axis; the radial positions (P0, P90, P180, P270) of the rotary table 13 of the tool 3 are detected by detecting operations at the respective angular positions; becomes the first straight line L1 passing through the midpoint of the line segment L01 connecting the positions P0, P180 of the tool 3 detected at the two angular positions A0, A180 opposed to each other in the first direction D1 and the first direction D1, and the second straight line L2 passing through the midpoint of the line segment L02 connecting the positions P90, P270 of the tool 3 detected at the two angular positions A90, A270 opposite each other in the second direction D2 and crossing the second direction D2 calculated; and the intersection point Pc of the first straight line L1 and the second straight line L2 is defined as the center position of the C axis.

Accordingly, the detection unit 20 of the present exemplary embodiment form, which only necessarily has to be able to detect the position of the tool 3 in the radial direction of the turntable 13, by an image sensor (the illumination 24 to the CCD camera 26, see 3 ) can be provided, which is set up to display the captured image 261 (see 5 ) to the side of the tool 3 to detect the position of the tool 3 in the image and to align it in the circumferential direction of the rotary table 13 .

According to the present exemplary embodiment, the center position of the C-axis within the prospective range (the straight line L1), which cannot be determined in the detecting operation at the angular positions A0, A180 at 0 and 180 degrees, can be replaced by the position (straight line L2) of the tool 3 calculated during the acquisition process at the angular positions A90, A270 at 90 and 270 degrees to determine the precise center of the C-axis. In other words, the center position of the C-axis can be measured with high precision by the detection operations at the total of four angular positions (A0, A90, A180, A270).

In the present exemplary embodiment, the detection unit 20 includes the illumination 24 set up to emit the parallel beam 28, the image pickup (the telecentric lens 25 and the CCD camera 26) set up to detect the parallel beam 28, and the arithmetic section 27 arranged to detect the tip position of the tool 3 positioned in the parallel beam 28 based on the captured image 261, wherein the captured image 261 is subjected to a known image processing in order to remove the shadow 281 of the in the parallel beam 28 positioned tool 3, the center position of the contour 282 of the tip of the tool 3 is calculated by edge detection, whereby the tip position 283 of the tool 3 is calculated.

As a result, the tip position of the tool 3 can be detected highly accurately by the optical detection by the detection unit 20 in a non-contact manner.

Furthermore, when the position is detected, it is only necessary that the tip of the tool 3 is in the parallel beam 28 between the illuminator 24 and the image pickup device (the telecentric lens 25 and the CCD camera 26), thereby achieving a simple detection operation .

In the present exemplary embodiment, the detecting unit 20, which includes a stopper for fixing to the turntable 13, can be prevented from shifting with respect to the placement position of the detecting unit 20 on the turntable 13 during the detecting operations at the respective angular positions.

Second exemplary embodiment

The 10A until 10C show a second exemplary embodiment of the invention.

In the first exemplary embodiment described above, to measure the center position of the C axis of the machine tool 1 (see 1 ) placed the detection unit 20 on the turntable 13 (see 2 and 3 ), the first straight line L1 is detected by the radial position detection process at the angular positions A0, A180 of the tool 3, the second straight line L2 is detected by the same detection process at the angular positions A90, A270, and the intersection point Pc of the first and second straight lines L1, L2 as the precise center position of the C-axis of the machine tool 1.

In contrast, the precise center position of the C-axis of the machine tool 1 is measured in the present exemplary embodiment by, in addition to detecting a radial position, a circumferential position of the tool 3 (i.e. a planar position along the surface of the rotary table 13) during the detection process at the Angular positions A0, A180 is detected.

As in 10A 1, a detection unit 20A is placed on the rotary table 13 set at the angular position A0.

In addition, the detecting unit 20A, whose basic structure is the same as that of the detecting unit 20 in the first exemplary embodiment, is configured to detect a coordinate in a depth direction of the image using an auto-focusing function. For example, to capture the coordinate using an auto focus function, the edge of the contour 282 of the shadow 281 of the tool 3 in the captured image 261 in 5 is detected to determine a focus position with the maximum contrast, thereby accurately detecting the coordinate in the depth direction of the image.

Accordingly, the radial position Rc and a circumferential position Cc of the tool 3 with respect to the turntable 13 can be detected by inserting the tool 3 into the detection unit 20</b>A placed on the turntable 13 . A planar position PA0 of the tool 3 on the rotary table 13 can be detected at the angular position A0 by the detection process described above.

As in 10B 1, the turntable 13 is moved to the angular position A180 after the detection operation is completed in the angular position A0, and the same detection operation is performed in the angular position A180, whereby a planar position PA180 of the tool 3 on the turntable 13 is measured.

As in 10C 1, after measuring the planar position PA0 and the planar position PA180, a center point PAc of a line segment LA connecting the planar position PA0 and the planar position PA180 is calculated by the arithmetic section 27. The exact center position of the C-axis of the machine tool 1 can be measured by the center point PAc.

According to the present exemplary embodiment, in addition to the same advantages of the first exemplary embodiment described above, since it is only necessary to perform the detecting operation for the tip of the tool 3 at the two positions (i.e., the angular positions A0, A180), work efficiency can be improved. to perform.

Further, the detection operations at the other angular positions (for example, the angular positions A90, A270) as in the first exemplary embodiment are not required in the present exemplary embodiment. Accordingly, if, for example, the angular positions A90, A270 are out of the range in which the detection operation can be performed due to structural limitations of the translational axes (X, Y, Z axes) of the machine tool 1, the precise center position of the C axis can pass through be measured during the detection process at the angular positions A0, A180.

Third exemplary embodiment

The 11A until 12C show a third exemplary embodiment of the invention.

The first and second exemplary embodiments described above, in which the detecting operations are performed at the angular positions A0, A180 and angular positions A90, A270, and the detecting operations at the angular positions A0, A180, respectively, require the detecting operations at the opposite sides across the center of the rotary table 13 Angular positions A0, A180.

In contrast, in the present exemplary embodiment, the detection operation for the tip position of the tool 3 from the angular position A0 is performed at each of a plurality of angular positions An (An < 180 degrees) as in the first exemplary embodiment, the detection results of which are calculated to center the precise position the C-axis of the machine tool 1 to measure.

It should be noted that a repeated description for the structure of the machine tool 1, the rotary table 13 and the detection unit 20, which are the same as in the first exemplary embodiment described above, will not be given in the present exemplary embodiment.

As in 11A 1, the rotary table 13 on which the detection unit 20 is placed is set at the angular position A0. Then, the tip of the tool 3 is inserted into the opening 23 of the detection unit 20, and the position of the tip is detected by the detection unit 20 to determine the position P0 of the tool 3. FIG.

As in 11B 1, the turntable 13 is then rotated 30 degrees to the next angular position A30, detecting a position P30 of the tool 3 by the same operation as performed in the angular position A0.

As in 11C As shown, the turntable 13 is further rotated 30 degrees to the next angular position A60, and a position P60 of the tool 3 is detected by the same operation as performed in the angular position A0.

As in 12A As shown, the turntable 13 is rotated to the next angular position A120, in which a position P120 of the tool 3 is detected by the same operation that was carried out in the angular position A0.

As in 12B As shown, the turntable 13 is rotated to the next angular position A150, in which a position P150 of the tool 3 is detected by the same operation that was carried out in the angular position A0.

As in 12C As shown, the positions P0 to P150 of the tool 3 detected at the above-described angular positions A0 to A150, respectively, draw an arc when plotted on a screen. For example, by applying the least squares method to the dot line of the positions P0 to P150 arranged in an arc, a position of a center point PBc of the arc can be calculated highly accurately, with the resultant center point PBc being the exact center position of the C-axis of the machine tool 1 can be determined.

The same advantages as those of the first exemplary embodiment described above can be obtained by the present exemplary embodiment. In addition, even if the range in which the detection operation can be performed is limited to less than 180 degrees due to structural limitations of the translational axes (X, Y, Z axes) of the machine tool 1, the precise center position of the C axis can be measured at the multiple positions by the detection process.

Modification(s) of the first to third exemplary embodiments

In the first to third embodiments described above, the image of the tip of the tool 3 is picked up by the detection unit 20 at the angular positions An during the detection process. However, it should be noted that the position of the tool 3 in the captured image is optionally different at each of the angular positions An.

As in 13 As shown, in the image 261 captured by the capturing unit 20, the position of the contour 282 of the shadow 281 of the tool 3 in the captured image 261 at the angular position A0 is sometimes different from the position at the angular position(s) An. However, if a displacement dc0 from the angular position A0 (double-dashed chain line) can be calculated on the captured image 261 by image processing, the coordinates of the tool 3 can be determined by compensating for the displacement. Accordingly, the position of the tool 3 in the captured image 261 may be different at each of the angular positions An.

Fourth exemplary embodiment

The 14 until 16 show a fourth exemplary embodiment of the invention.

In the present exemplary embodiment, a displacement (offset) between the center position of the A-axis of the machine tool 1 and the tip of the tool 3 is measured.

It should be noted that in the present exemplary embodiment, repeated description of the configurations of the machine tool 1 and the detection unit 20 used for measurement, which are the same as in the first exemplary embodiment described above, will be omitted.

In the present exemplary embodiment, the detection unit 20 is placed on the turntable 13 .

The detection unit 20 is arranged so that the opening 23 is located at the center of the turntable 13 (rotational center position of the C-axis). Then, the orientation of the detection unit 20 is adjusted so that the parallel beam 28 is aligned with the X-axis direction of the machine tool 1 . The orientation of the detection unit 20 is optionally adjusted by rotating the turntable 13 around the C-axis.

After the detecting unit 20 is placed, the spindle head 17 is moved near the detecting unit 20 along the respective axes by operating the machine tool 1 to insert the tip of the tool 3 attached to the spindle 18 into the opening 23 for the detecting operation.

As in 15A As shown, the tip of the tool 3 is inserted into the hole 23 by operating the machine tool 1 along the respective axes, turning the tool 3 in the direction of the Y-axis “+” direction (angular position A0 around the A-axis) through the A-axis rotation of the machine tool 1 is aligned. Further, by operating the machine tool 1 along the Y and Z axes, the peak position 283 of the shadow 281 of the tool 3 in the captured image 262 is adjusted to be positioned at the center of the image 262 captured by the capturing unit 20 . Then the Y-axis position and Z-axis position (Y1, Z1 in 16 ) of the machine tool 1 is recorded at this time.

As in 15B 1, the tool 3 is then aligned by the A-axis rotation of the machine tool 1 in the Y-axis "-" direction (angular position A180 versus angular position A0 across the A-axis). In this state, the tip of the tool 3 is inserted into the opening 23 along the respective axes by the operation of the machine tool 1 . Further, by operating the machine tool 1 along the Y and Z axes, the peak position 283 of the shadow 281 of the tool 3 in the captured image 262 is adjusted to be positioned at the center of the image 262 captured by the capturing unit 20 . Then the Y-axis position and Z-axis position (Y2, Z2 in 16 ) of the machine tool 1 is recorded at this time.

There, as in 16 As shown, the tip of tool 3 is positioned at the same points at angular positions A0 and A180, the difference between the Y-axis and Z-axis po Position Y1, Z1 at the angular position A0 and the Y-axis and Z-axis positions Y2, Z2 at the angular position A180 of the machine tool 1 are derived from the deviation of the center of rotation of the A-axis (a rotation axis 171 of the spindle head 17).

Accordingly, the shift (offset) between the center position of the A-axis of the machine tool 1 and the tip of the tool 3 can be calculated as a half of the difference between the positions in the respective axes at the angular position A0 and the angular position A180 (Y = (Y1 -Y2)/2, Z = (Z1-Z2)/2).

According to the present exemplary embodiment, the same advantages as in the first exemplary embodiment described above can be obtained in measuring the displacement (offset) between the center position of the A-axis and the tip of the tool 3 .

Fifth exemplary embodiment

The 17 until 20 show a fifth exemplary embodiment of the invention.

In the present exemplary embodiment, the coordinates at which the center position of the A-axis coincides with the tip of the tool 3 are measured in a so-called cradle-type machine tool 1A.

In 17 is the rotary table 13 supported by the movable table 12 (see 1 ) is supported via a cradle 131 to be rotatable about the C-axis with respect to the cradle 131. The cradle 131 is rotatable about the A-axis by a pair of pivots 132 with respect to the movable table 12 .

It should be noted that the spindle head 17 of the machine tool 1A fixed to the slider 16 (see Fig 1 ) is not rotatable about the A-axis but is kept constant to face downward in the Z-axis.

In the present exemplary embodiment, the detection unit 20 is placed on the turntable 13 . A repeated description of the detection unit 20, which is the same as that in the first exemplary embodiment described above, is omitted here.

The detection unit 20 is arranged so that the opening 23 is located at the center of the turntable 13 (rotational center position of the C-axis). Then, the orientation of the detection unit 20 is adjusted so that the parallel beam 28 is aligned with the X-axis direction of the machine tool 1A. The orientation of the detection unit 20 is optionally adjusted by rotating the turntable 13 around the C-axis.

After the detecting unit 20 is placed, the spindle head 17 is moved near the detecting unit 20 along the respective axes by operating the machine tool 1A to insert the tip of the tool 3 mounted on the spindle 18 into the opening 23 for the detecting operation.

As in 18 (A) As shown, the tip of the tool 3 is inserted into the hole 23 by operating the machine tool 1A along the respective axes, rotating the rotary table 13 in the Y-axis "+" direction (angular position A0 around the A-axis) by A-axis rotation facing the cradle 131 .

Furthermore, as in 19A shown, by operating the machine tool 1A along the Y and Z axes with the cradle 131 positioned at the angular position A0, the peak position 283 of the shadow 281 of the tool 3 in the captured image 263 is adjusted to be at the center of the from of the captured image 263 obtained by the capturing unit 20 is positioned. Then the Y-axis position and Z-axis position (Y1, Z1 in 20 ) of the machine tool 1A at this time is recorded.

Then, as in 18 (B) shown, with the rotary table 13 facing the Y-axis "-" direction (angular position A180 versus angular position A0 transverse to the A-axis) by the A-axis rotation of the cradle 131, the tip of the tool 13 inserted into the opening 23 by the Machine tool 1A is operated along the respective axes.

As in 19B 1, by operating the machine tool 1A along the Y and Z axes with the cradle 131 positioned at the angular position A180, the peak position 283 of the shadow 281 of the tool 3 in the captured image 263 is adjusted to be at the center of the captured image 263 obtained by the capture unit 20 is positioned. Then the Y-axis position and Z-axis position (Y2, Z2 in 20 ) of the machine tool 1A at this time is recorded.

As in 20 shown, since the tip of the tool 3 is positioned at the same points at the angular positions A0 and A180, the difference between the Y-axis and Z-axis positions Y1, Z1 at the angular position A0 and the Y-axis and Z -Axis position Y2, Z2 at the angular position A180 of the machine tool 1A from the bore Effect of the center of rotation of the A-axis of the cradle 131 derived.

Accordingly, the coordinates at which the center position of the A-axis of the machine tool 1A coincides with the tip of the tool 3 can be calculated based on the respective axis positions at the angular positions A0 and A180 by a formula Y=(Y1+Y2)/2, Z= (Z1+Z2)/2 can be determined.

According to the present exemplary embodiment, the same advantages as in the first exemplary embodiment described above can be obtained in determining the coordinates at which the center position of the A-axis coincides with the tip of the tool 3 .

Sixth exemplary embodiment

The 21A until 23C show a sixth exemplary embodiment of the invention.

In the present exemplary embodiment, a displacement (offset) between the center position of the A-axis of the machine tool 1 and the tip of the tool 3 is measured using the same components as described in the fourth exemplary embodiment described above.

However, while in the fourth exemplary embodiment, the Y-axis positions Y1, Y2 and the Z-axis positions Z1, Z2 of the machine tool 1 are detected at two points (i.e., the angular position A0 and the angular position A180 facing the angular position A0 transverse to the A-axis (i.e., at a 180-degree interval), the detection operation for the Y-axis position and the Z-axis position is performed at a plurality of angular positions An within a 180-degree range from the angular position A0 in the present embodiment.

As in 21A shown, with the tool 3 initially aligned in the Y-axis "+" direction (angular position A0 about the A-axis) by the A-axis rotation of the machine tool 1 (ie rotation of the spindle head 17 about the rotation axis 171), the tip of the tool 3 is inserted into the opening 23 along the respective axes by operating the machine tool 1 .

Then, as in 21B 1, after the tool 3 is positioned at the angular position A0, by operating the machine tool 1 along the Y and Z axes, the peak position 283 of the shadow 281 of the tool 3 in the captured image 264 is adjusted to be at the center of the from of the captured image 264 obtained by the capturing unit 20 is positioned. Then, the Y-axis position and the Z-axis position of the machine tool 1 at that time are recorded. The recorded Y-axis position and Z-axis position define the center position of the A-axis Q0 at each of the angular positions An.

Then, with the tool 3 positioned at an angular position A30 (rotated 30 degrees from the angular position A0) by the A-axis rotation of the machine tool 1, the tip of the tool 3 is inserted into the hole 23 by operating the machine tool 1 along the respective axes . After the peak position 283 of the shadow 281 of the tool 3 in the captured image 264 is adjusted so that it is at the center of the captured image 264 obtained by the capturing unit 20, the Y-axis position and the Z-axis position (center position of the A-axis Q30) of the machine tool 1 recorded at this time.

Further, after the tool 3 is positioned at the angular position A60 (rotated by 60 degrees from the angular position A0) by the A-axis rotation of the machine tool 1, the Y-axis position and the Z-axis position (center position of the A-axis Q60) become the Machine tool 1 through the same process as recorded for angular positions A0, A30.

The Y-axis position and the Z-axis position (A-axis center position Q90, Q120, Q150, Q180) of the machine tool 1 at the angular positions A90, A120, A150, A180 are recorded in the same manner.

As in 21C 1, the center positions Qn (Q0 to Q180) of the A-axis at the angular positions An (A0 to A180) detected after repeating the above-described detecting operation draw an arcuate dotted line QC. The position of a center QCc (the tip position of the tool 3 common to the angular positions An) of the arcuate dotted line QC can be e.g. B. can be calculated with the method of least squares. From the resulting center point QCc, the displacement (offset) between the center position of the A-axis Qn of the machine tool 1 and the tip of the tool 3 can be accurately measured.

The same advantages as in the first and fourth exemplary embodiments described above can be obtained by the present exemplary embodiment. In addition, even if the possible area where the detection process is carried out can be, due to structural limitations of the translational axes (X, Y, Z axes) of the machine tool 1 is limited to less than 180 degrees, the displacement (offset) between the center position of the A-axis Qn and the tip of the tool 3 by the detecting operation at the multiple angular positions An can be accurately measured.

Modification(s) of the sixth exemplary embodiment

As in 22 shown, the shift (offset) between the center position of the A-axis Qn and the tip of the tool 3 measured in the sixth embodiment described above is recorded in an NC device of the machine tool 1 to be used as a correction value during the operation of the Machine tool 1 to be referenced.

When recorded in the NC device of the machine tool 1, a distance D (offset) from the center QCc (the tip position of the tool 3) to the actual center position of the A-axis Qn is required. By calculating the least squares method on the arcuate dotted line QC formed from the center positions of the A-axis Qn, an approximate arc radius can be obtained which is the distance D (approximate value) from the center point QCc to the center position of the A-axis Qn in addition to the position of the center QCc. The radius can be viewed as the actual distance D between the center point QCc and the center position of the A-axis Qn.

When recorded in the NC device of the machine tool 1, the distance D is to be divided into a component Dz in a Z-axis direction parallel to the tool 3 and a component Dy in a Y-axis direction perpendicular to the tool 3. An angle θ of a line segment connecting the center position of the A-axis Qn and the tip of the tool 3 (center point QCc) thus becomes required. However, the least squares method used to calculate the center point QCc does not show the angle θ of the line segment to provide the approximate arc radius (distance D).

As in 23A 1, the A-axis center positions Qn (sampling points) detected in the form of the arcuate dotted line QC at the above-described plurality of angular positions An (A0 to A180) show a deviation (radial offset) in addition to the above-described error in determining the angle θ in relation to the approximate arc of the dot line QC. Further, when reference lines Ln extending from the center QCc are drawn at angles (0 to 180 degrees) to define the angular positions An for detecting the central position of the A-axis Qn, the central position of the A-axis has Qn in each of the angles has a variation (circumferential offset) with respect to the reference lines Ln.

The following procedures are applicable to determine the most appropriate value of the above angle θ under such an error distribution.

23B Fig. 14 shows a first process in which the A-axis center position Q90 is used for the tool 3 to be aligned with the Z-axis (angular position A90). Specifically, a line segment extending from the center point QCc to the center position of the A axis Q90 is drawn, and an angle formed by the line segment and the Z axis is defined as θ.

The above operation, which does not provide full optimization, is the most appropriate as a reference value.

In a second process, which 23C As shown, the angle θ is defined by an angle subtended between a line segment extending from the center point QCc to a point (e.g. center position of the A-axis Q130 (rotated 130 degrees from the angular position A0)) where the tool 3 is oriented at a predetermined angle (eg, 40 degrees) with respect to the Z-axis, and a reference line L130 (which forms 40 degrees with respect to the Z-axis) is formed.

Further, the angles θn with respect to the respective reference lines Ln measured for the A-axis center positions Qn at the angular positions An are optionally determined and averaged.

Such a process, while complicated, can provide the angle θ that has full optimization.

The angle θ, which is optionally determined by equally dividing the entire range of the center positions Qn at the plurality of angular positions An, is alternatively determined with an increased or decreased sampling density of a part of the angular range.

When the angle θ is determined through the above-described operation, the Dz component and the Dy component in the Z-axis direction and the Y-axis direction perpendicular to the tool 3 (see FIG 22 ) can be calculated as Dz = Dcosθ and Dy = Dsinθ.

Modification(s) of the first to sixth exemplary embodiments

In the first to sixth exemplary embodiments described above, the tip position of the tool 3 is detected by the detection units 20, 20A.

For example, in the first exemplary embodiment, the tip position of the tool 3 is detected at the center of the captured image 261 of the CCD camera 26 as shown in FIG 5 12, where the coordinates (Tv, Th) of the tip position 283 of the tool 3 are determined based on the contour 282 of the shadow 281 of the tip of the tool 3 represented in the captured image 261. FIG.

At this time, depending on the shape of the tip of the tool 3, the coordinates sometimes cannot be accurately grasped, e.g. B. because of the irregular contour of the tool 3.

On the other hand, in order to easily and accurately detect the tip position (Tv, Th) of the tool 3, the following method is applicable.

Seventh exemplary embodiment

As in 24A shown, the shadow 281 of the tip of the tool 3 appears in the captured image 261 of the CCD camera 26 (see Fig 3 ) as in 5 . The tip position 283 of the tool 3 appears at a part of the contour 282 of the shadow 281 whose coordinates (Tv, Th) are to be measured.

In the present exemplary embodiment, while the tool 3 is rotated with respect to the CCD camera 26, the captured image 265 is captured by the CCD camera 26 (similar to the captured images 261 to 264 in the first to sixth exemplary embodiments) and captures the contour 282 of the tool 3 based on the captured image 265 .

In the present exemplary embodiment, as the tool 3 rotates, the contour 282 appearing in the captured image 265 is symmetrical with respect to the center of rotation such that a central axis 284 of the tool 3 can be accurately captured given the symmetrical nature of the contour 282 and the tip position 283 of the tool 3 can be detected as the intersection of the central axis 284 and the contour 282.

In the present exemplary embodiment, when detecting the center axis 284 of the tool 3 based on the contour 282, the following arithmetic processing is performed.

As in 24B shown, the tool 3 is set at a predetermined angular position (e.g. the in 21B angular position A90 shown) positioned in the captured image 265, wherein the tool 3 extends in an extension direction D90. A plurality of transverse lines 30 running perpendicularly to the direction of extent D90 and which traverse the contour 282 are then defined in parallel along the direction of extent D90 at a predetermined distance.

As in 24C As shown, the contour 282, two intersections 31, 32 and further a midpoint 33 of the two intersections 31, 32 for each of the defined plurality of transverse lines 30 are detected. Subsequently, a straight line running through the center points 33 of the transverse lines 30 and defined as the central axis 284 of the tool 3 is determined.

The present exemplary embodiment, in which the extending direction Dn (angular positions An, orientation of the tool 3, approximate axis direction) of the tool 3 is used to detect the axis of rotational symmetry, can accurately detect the central axis 284 of the tool 3 and calculate the coordinates (Th, Tv ) of the tip position 283 of the tool 3 as the intersection of the precise central axis 284 and the contour 282 with high precision.

At this time, while the center of each of the plurality of transverse lines 30 is detected to detect the central axis 284 and the intersections with the contour 282 are detected to detect the peak position 283, the centers and the intersections can be determined by geometric arithmetic, respectively Processing are determined so that the tip position 283 and the center position of the axis of rotation (A-axis or C-axis) of the tool 3 can be determined highly accurately and easily.

In the present exemplary embodiment, the orientation of the tool 3 (extension direction Dn) can be set at an arbitrary angle (angular position An).

In 25A the tool 3 is set to the angular position A150, with a plurality of transverse lines 30 being defined perpendicular to an extension direction D150.

As in 25B As shown, two intersection points 31, 32 and the center point 33 are detected for each of the transverse lines 30, the coordinates (Th, Tv) of the tip position 283 of the tool 3 as the intersection of the central axis 284 passing through the plurality of centers 33 and the contour 282 can be accurately detected.

Eighth exemplary embodiment

In the seventh exemplary embodiment described above, to detect the central axis 284 of the tool 3 based on the contour 282, the center points of the plurality of transverse lines 30 are detected.

In contrast, in the present exemplary embodiment, the central axis 284 of the tool 3 is detected by pattern recognition of each side of the contour 282 in the form of a rotationally symmetrical figure.

As in 26A shown, the tool 3 is set at a predetermined angular position (e.g. the in 21B angular position A90 shown) is positioned in the captured image 265, in which the tool 3 extends in the extension direction D90. Subsequently, a shape 41 of one side (one of two parts of the contour 282 divided into two by a line running along the extending direction D90) of the contour 282 with respect to the extending direction D90 is detected as a reference pattern 40.

As in 26B shown, after the detection of the reference pattern 40, a symmetry pattern 42 is calculated, which matches an inverted shape of the reference pattern 40, wherein a shape 43 that matches the symmetry pattern 42 is detected from the contour 282. When the symmetry pattern 42 is detected, a straight line passing through a center point of the reference pattern 40 and the symmetry pattern 42 (ie, an axis of line symmetry of the reference pattern 40 and the symmetry pattern 42) is defined as a central axis 284 of the tool 3.

The present exemplary embodiment, in which the extending direction Dn (angular positions An, orientation of the tool 3, approximate axis direction) of the tool 3 is used for pattern recognition of the contour 282 per side, can accurately detect the central axis 284 of the tool 3 and obtain the coordinates (Th , Tv) of the tip position 283 of the tool 3 based on the intersection of the precise central axis 284 and the contour 282 with high accuracy.

The pattern recognition per one side of the contour 282 can be carried out in the form of the detection of the reference pattern 40 and the symmetry pattern 42 by geometric arithmetic processing, whereby a highly precise and simple measurement of the center position of the tip position 283 and/or the axis of rotation (A-axis or C-axis) of the tool 3 is made possible.

Ninth exemplary embodiment

In the seventh exemplary embodiment described above, after detecting the central axis 284 of the tool 3 based on the contour 282, the intersection of the central axis 284 and the contour 282 is detected to determine the tip position 283 of the tool 3.

In contrast, in the present exemplary embodiment, an auxiliary contour line is defined in the contour 282 of the tip portion of the tool 3 to allow determination of the tip position of the tool 3 even if the shape of the contour 282 of the tip portion is blurred as the tool 3 rotates is, for example, due to multiple protrusions at the tip of the tool 3 and an eccentric tip shape of the tool 3.

As in the 27A and 27B 1, it is assumed that at the tip portion of the tool 3, there are provided a pair of blade edges 3T facing each other across the center of rotation. In 27B the blade edges 3T indicated by solid lines move in accordance with the rotation of the tool 3 to the respective positions indicated by double-dashed chain lines.

In the exemplary embodiments described above, the image of the tip portion of the tool 3 is picked up by the CCD camera 26 in the lateral direction of the tool 3 (in a direction crossing the axis of rotation of the tool 3).

For example, assuming that the image of the tool 3 from the CCD camera 26 is taken from a lower side in 27B is captured, both blade edge pairs 3T can be covered by a focusing range Rf0 of the CCD camera 26 when the blade edge pairs 3T face each other in a direction perpendicular to the optical axis of the CCD camera 26 (a state shown in 27B represented by solid lines). However, when the blade edge pair 3T is brought close to a state aligned with the optical axis of the CCD camera 26 in accordance with the rotation of the tool 3 (in 27B indicated by double-dashed chain lines), a difference in distance between the CCD camera 26 and the blade edges 3T increases, with one of the blade edges 3T increasing in a warp away from the CCD camera 26 depth of field Rf1 and the other of the blade edges 3T is in a depth of field Rf2 close to the CCD camera 26, so that both blade edges of the pair 3T cannot be focused by the CCD camera 26.

As described above, the distance from the pair of blade edges 3T to the CCD camera 26 changes cyclically in accordance with the rotation of the tool 3, resulting in a part of the image picked up by the CCD camera 26 being blurred.

As in 27C shown, the contour 282 of the shadow 281 of the tool 3, which is clear except for a tip thereof, has a blurred portion at the tip due to the displacement of the pair of blade edges 3T in the direction of the optical axis of the CCD camera 26. As a result, the coordinate of the Tip position 283 of the tool 3 can not be determined as the intersection of the central axis 284 and the contour 282 unlike the seventh to eighth exemplary embodiments described above.

In contrast, in the present exemplary embodiment, while the central axis 284 is detected in the same manner as in the seventh or eighth exemplary embodiment described above, an auxiliary contour line is defined on the contour 282 of the tip portion of the tool 3, and an intersection of the auxiliary contour line and of the central axis 284 is determined as the tip position 283 of the tool 3 . In detail, the procedure is as follows.

As in 28A 1, after the central axis 284 has been determined in the shadow 281 of the tool 3, a pair of parallel lines Ma, Mb parallel to the central axis 284 are defined on respective sides of the central axis 284 at a predetermined distance Ofs. Here, the predetermined distance Ofs is defined such that the intersections Ca, Cb between the pair of parallel lines Ma, Mb and the contour 282 are present at a non-blurred part of the contour 282 . The predetermined distance Ofs, which is optionally adjusted in view of the condition of the contour 282, is alternatively determined based on a design dimension of the blade edges 3T of the tool 3.

In 28B After the determination of the intersection points Ca, Cb between the pair of parallel lines Ma, Mb and the contour 282, an auxiliary contour 285 running through the intersection pair Ca, Cb perpendicular to the central axis 284 is defined, with the intersection of the central axis 284 and the auxiliary contour 285 as the peak position 283 of the tool 3 is determined.

In the present exemplary embodiment, the defined auxiliary contour 285 enables the determination of the tip position 283 of the tool 3 as the intersection of the central axis 284 and the auxiliary contour 285 even if the shape of the contour 282 of the tip portion is blurred during the rotation of the tool 3, for example due to several Protrusions at the tip of the tool 3 (e.g. the pair of blades 3T) and an eccentric tip shape of the tool 3. Accordingly, the tip position 283 and/or the center position of the axis of rotation (A-axis or C-axis) of the tool 3 can be obtained by simple calculation for the Tool 3 can be measured very precisely with different tip shapes.

Other Exemplary Embodiment(s)

It should be noted that the present invention is not limited to the exemplary embodiments described above, but includes modifications and the like as long as such modifications and the like are compatible with an object of the invention.

In the exemplary embodiments described above, the rotational center position of the C-axis or the A-axis of the five-axis control machine tools 1, 1A is measured. However, the machine tool and the axis for applying the invention can be selected arbitrarily.

For example, the machine tool is optionally a five-axis control machine tool that has A and B axes as rotation axes, and the rotation center position of the B axis is optionally measured. Furthermore, the machine tool, which is optionally a four-axis controlled machine tool, a six-axis controlled machine tool or the like, only has to have at least one axis of rotation whose central position is of interest.

In the exemplary embodiments described above, the detection unit 20 or 20</b>A is used to detect the tip position of the tool 3 . However, the detection units 20, 20A do not necessarily form the parallel beam 28, but are optionally set up to pivot a laser beam in parallel (pseudo-parallel beam) in order to scan a target object. Furthermore, the detection unit, which is only necessary to be contactless with the tool 3, is optionally a detector with other detection means.

INDUSTRIAL APPLICABILITY

The invention is applicable to a method of measuring a rotational axis center position of a machine tool.

Reference List

1, 1A

machine tool,

2

Workpiece,

3

Tool,

3d

blade edge,

9

Steering,

91

motion control,

92

tool position detector,

11

Bed,

12

moving table,

13

turntable,

131

cradle,

132

cones,

14

Pillar,

15

Saddle,

16

glider,

17

spindle head,

171

axis of rotation,

18

Spindle,

20.20A

registration unit,

21

Housing,

22

leg that includes a stopper,

23

Opening,

24

Lighting,

25

telecentric lens,

26

CCD camera (image capture),

261 to 265

captured image,

27

arithmetic section,

28

parallel beam,

281

The shade,

282

Contour,

283

top position,

284

central axis,

285

auxiliary contour line,

29

acquisition target,

31:32

intersection,

33

Focus,

A0 to A270,An

angular position,

Ca, Cb

intersection,

cc

perimeter position,

D

Distance,

D1

first direction

D2

second direction

dc0

Shift,

dy

y axis direction component,

dz

z-axis directional component,

L01, L02

line segment,

L1

first straight line

L130

reference line,

L2

second straight line

L.A

line segment,

Ln

reference line,

ma, mb

parallel line,

Ofs

predetermined distance,

P0 to P270

tool tip position,

PA0, PA180

planar position,

PAc

Focus,

PBc

Focus,

personal

intersection,

Q0 to Q180, Qn

A axis center position,

QC

dotted line,

QCc

Focus,

rc

radial position,

Th, TV

coordinates of the top position,

Tx0 to Tx270

x-axis coordinate,

Ty0 is Ty270

y-axis coordinate,

Y1, Y2

y-axis position,

Z1,Z2

z-axis position,

θ, θn

angle

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• JP 2019152574 A [0008]
• JP2020028922A [0008]

Claims (11)

A method of measuring a rotational axis center position of a machine tool, comprising: attaching a tool to a spindle; Placing a detection unit on a table, which is set up to detect a position of the tool without contact; repeatedly performing detection operations for adjusting the tool and the table at predetermined angular positions with respect to a rotation axis of a measurement target and detecting a position of the tool with respect to the table using the detection unit at each of the angular positions; and Calculating the rotation axis center position based on the positions of the tool at the angular positions detected in the multiple detections. Method for measuring a rotary axis center position of a machine tool claim 1 , wherein the detection unit is configured to detect without contact that a tip of the tool is at a specific position in the detection unit, and in the detection operations after the spindle and the table are relatively moved to move the tool and the table to the predetermined set angular positions, and the relative position of the spindle and the table is adjusted so that the tool is positioned at the determined position of the detection unit at each of the angular positions, the position of the tool with respect to the table at each of the angular positions based on the relative position of the spindle and the table is detected. Method for measuring a rotary axis center position of a machine tool claim 1 or 2 , wherein the detection unit is arranged to detect the positions of the tool in a radial direction of the table, the tool and the table are set in four angular positions, the two angular positions opposite to each other in a first direction transverse to the axis of rotation, and two angular positions which are opposed to each other in a second direction crossing the first direction transverse to the axis of rotation, the detection operations being carried out at the respective angular positions to detect the positions of the tool in the radial direction of the table, and a first straight line which passes a midpoint of a line segment connecting the positions of the tool detected at the two angular positions opposite to each other in the first direction and crossing the first direction, and a second straight line passing a midpoint of a line segment which the Connecting positions of the tool detected at the two angular positions opposing each other in the second direction and crossing the second direction are calculated, with an intersection point of the first straight line and the second straight line being determined as a center position of the axis of rotation. Method for measuring a rotary axis center position of a machine tool claim 1 or 2 , wherein the detection unit is arranged to detect the positions of the tool along a surface of the table, the tool and the table are set at two angular positions opposite to each other transversely to the axis of rotation, the detection operations being carried out at the respective angular positions in order to detecting positions of the tool along the surface of the table, and calculating a midpoint of a line segment connecting the positions of the tool in the two detecting operations, the midpoint being determined as a center position of the axis of rotation. Method for measuring a rotary axis center position of a machine tool claim 1 or 2 , wherein the detection unit is adapted to detect the positions of the tool in a radial direction of the table, the tool and the table are set at a plurality of angular positions within a predetermined angular range around the axis of rotation, the detection operations being carried out at the respective angular positions to detecting the positions of the tool in the radial direction of the table, and plotting the positions of the tool detected in the plurality of detections to calculate a center position of the axis of rotation by an approximate calculation. Method for measuring a rotational axis center position of a machine tool according to one of Claims 1 until 5 , wherein the detection unit has a stopper for fixing to the table. Method for measuring a rotational axis center position of a machine tool according to one of Claims 1 until 6 , wherein the detection unit comprises an illumination set up to emit a parallel beam, and an imager configured to capture the parallel beam, and a tip position of the tool positioned in the parallel beam is captured based on an image captured by the imager. Method for measuring a rotary axis center position of a machine tool claim 7 wherein the image is captured by the imager while the tool is rotated with respect to the imager, a contour of the tool is captured from the image, a central axis of the tool is captured based on a symmetry of the contour, and an intersection of the central axis and the contour is determined as the tip position of the tool. Method for measuring a rotary axis center position of a machine tool claim 8 , wherein in a case where the intersection point of the central axis and the contour is determined as the tip position of the tool, a pair of parallel lines are defined on respective sides of the central axis at a predetermined distance, an auxiliary contour line is defined which is an intersection point of the pair of parallel lines and the contour and is perpendicular to the central axis, and the intersection of the central axis and the auxiliary contour line is determined as the tip position of the tool. Method for measuring a rotary axis center position of a machine tool claim 8 or 9 , wherein a plurality of transverse lines traversing the contour are defined in an extending direction of the tool, two intersections of each of the transverse lines and the contour, and a midpoint of the two intersections being detected for each of the transverse lines, one through the midpoint each of the transversal straight lines is determined as the central axis of the tool. Method for measuring a rotary axis center position of a machine tool claim 8 or 9 , wherein a shape of one side of the contour with respect to an extending direction of the tool is detected as a reference pattern, wherein a symmetry pattern whose shape matches an inverted shape of the reference pattern is detected from the contour, with a straight line having a center point of the reference pattern and the symmetry pattern is determined as the central axis of the tool.

Images