JP2007333712A - Apparatus for measuring angle of inclination, machine tool having apparatus mounted, and method of calibrating angle of inclination of machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology of measuring an angle of inclination capable of taking a wide measurement range of the angle of inclination and capable of automatic or semi-automatic accurate measurement independent of a shape of a target to be measured. <P>SOLUTION: An apparatus 2 for measuring the angle of inclination includes a rotary encoder 21 whose body is fixed to the target with which the angle of inclination is to be measured, an electronic level 22 mounted on a rotary shaft of the rotary encoder 21 to integrally rotate with the rotary shaft 111, and a rotary shaft rotating mechanism 23 for rotating the rotary shaft to put the level 22 in a horizontal posture. It includes the rotary shaft rotating mechanism 23 on a table 51 of a machine tool 5. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides a tilt angle measuring device that is not complicated in structure, has a wide tilt angle measurement range, does not depend on the shape of the measurement object, and can perform automatic or semi-automatic high-precision measurement. And a tilt angle calibration method.

  Inclination angle measuring equipment is used to inspect the inclination of ground and buildings, detect attitudes of vehicles, ships, aircraft, etc., detect sluice gates of dams, lift of bridges, measure inclination angles of inclined circular tables used in machine tools, etc. It is used for various purposes.

  Conventionally, for example, (1) a technique for measuring the tilt angle of a building using a pendulum (Patent Document 1), (2) a mass body is enclosed in a cylindrical container, and a displacement in which the lower surface of the container is distorted is detected. Technology to measure the inclination angle of dams, etc. (Patent Document 2), (3) The ultrasonic waves are emitted from a plurality of locations toward the measurement object, and the delay time difference is set as a time series based on the reflected ultrasonic waves. Technology for calculating and measuring the tilt angle of the measurement object (Patent Document 3), (4) Technology for measuring the tilt angle by detecting the strain of the leaf spring by the load by the weight (Patent Document 4), (5) In the container (Patent Document 5), (6) An angle difference of 90 ° between the outer surface of a pendulum that swings in any direction. Technology to measure the tilt direction and tilt angle by arranging two displacement sensors with Documents 6), (7) Techniques for measuring the tilt direction and tilt angle of a dish by determining the position of a spherical magnetic body arranged on a non-magnetic dish with a magnetic sensor (Patent Document 7), (8) A technique (Patent Document 8) that measures a rotation angle, that is, an inclination angle of a disk by attaching a disk with an unbalanced weight to a rotating shaft of a motor and detecting a load current is known.

JP-A-2005-300196 JP 2005-233918 A JP-A-2005-233844 JP 2005-106643 A JP 2000-2633 A JP 11-94546 A JP-A-8-152321 Japanese Patent Publication No. 6-63765 JP 2001-157951 A Kunio Naito: “Angle indexing device and its inspection method, precision machine” Vol. 44, no. 5 (1978) pp. 5-7. 557-563

  In each of the above-described conventional techniques, the measurement range is at most about 0 ° ± 5 ° for the measurement range because of the configuration. In each of the above-described conventional techniques, the measurement accuracy is at most 0.1 ° to 0.01 °, and it cannot be applied to applications that require higher measurement accuracy.

  For example, in a high-resolution tilt table machine tool, the tilt angle of the table can be rotated within a range of at least 0 ° ± 90 ° (0 ° means horizontal) and has a high tilt angle resolution. ing. When calibrating the tilt angle of the table, it is necessary to measure the tilt angle of the table on the order of at least 0.0001 ° using a tilt measuring device. That is, the above-described conventional techniques cannot be used for calibration of the tilt angle of the table of this type of tilt table type machine tool.

  On the other hand, a tilt angle measurement technique combining an autocollimator and a multi-faced reflecting mirror is also known (Patent Document 9). However, this technique has a problem that the structure becomes complicated because a laser light source must be used although the tilt angle can be measured with high measurement accuracy (for example, on the order of 0.0001 °).

  In addition, a tilt angle measurement technique using a clinometer that combines a level and an angle scale plate (precision scale disk) is also known (Non-Patent Document 1). In this measurement technology, it is configured so that the level can rotate with respect to the angle scale plate fixed to the main body, and by fixing the main body to the measurement target and adjusting the level side to be always horizontal, The tilt angle of the measurement object can be measured with high accuracy in a wide tilt angle range. However, this technique requires a certain amount of familiarity with the tilt angle measurement, and the level must be visually confirmed (that is, automatic measurement is not possible), so it takes a long time to measure. There's a problem.

  Furthermore, although not described in the literature, as a technique for measuring the tilt angle, a technique combining a sine bar (a rod-like body supported at both ends with rollers) and a precision level is also known. However, with this technique, it is possible to measure the tilt angle with high accuracy (for example, accuracy of the order of 0.0001 °), but the measurement range of the tilt angle is limited (measurement of 0 ° ± 90 ° is not possible). ) Problem. Further, although not mentioned in the literature, a tilt angle measurement technique is also known in which a rotary shaft of a rotary encoder is coupled to a rotation center of a measurement target. With this technique, it is possible to realize a tilt angle measuring apparatus that can measure the accuracy of the order of 0.0001 ° (that is, the resolution of the rotary encoder) and has a measurement range of 0 ° ± 90 °. However, depending on the shape of the measurement object, it is not easy to specify the rotation center, and even if the rotation center of the measurement object can be specified, the rotation axis of the rotary encoder can actually be coupled to the rotation center. In many cases, measurement is not possible.

An object of the present invention is to provide an inclination angle measuring device that is not complicated in structure, can take a wide inclination angle measurement range, does not depend on the shape of the object to be measured, and can perform automatic or semi-automatic high-precision measurement. Is to provide.
Another object of the present invention is to provide a tilting table type machine tool capable of machining while measuring a tilt angle with high accuracy.

  Still another object of the present invention is to provide a tilt angle calibration method for a tilt table type machine tool capable of correcting the tilt angle of the tilt table.

The gist of the tilt angle measuring device of the present invention is summarized as (1) to (4).
(1) “A rotary encoder whose main body is fixed to a tilt angle measurement target;
A level attached to the rotary shaft of the rotary encoder and rotating integrally with the rotary shaft;
A rotating shaft rotating mechanism that rotates the rotating shaft so that the level is in a horizontal posture;
An inclination angle measuring device comprising: "
As the rotating shaft rotating mechanism, for example, a mechanism that directly acts on the rotating shaft and rotates the rotating shaft, such as a rotary actuator, can be adopted, or it can rotate indirectly by acting on a jig for mounting the level. The shaft may be rotated.

(2) “The spirit level includes a spirit level attitude detector that detects attitude and outputs attitude information, and the rotation shaft rotation mechanism rotates the rotation axis based on the attitude information. The tilt angle measuring device according to (1). "
Specifically, an electronic level with a built-in level attitude detector can be used as the level. The spirit level only needs to be able to output at least information about whether the spirit level is in a horizontal orientation or in which direction the center of rotation is shifted from the horizontal as the orientation information. There is no need to output the value of.

(3) “The level includes a level attitude detector that detects attitude and outputs attitude information, and the rotating shaft rotation mechanism rotates the rotation axis based on the attitude information. The tilt angle measuring device according to (1). "
Specifically, a spirit level attitude detector is connected to a torsion joint by a well-known angle measurement system or a force balance servo system including a laser beam generator, a multi-faceted mirror attached to the level, and a laser beam receiver. The position of the supported pendulum can be constituted by a well-known angle measurement system that detects the position by a photo sensor or an electric gap sensor.

(4) The tilt angle measuring device according to any one of (1) to (3), wherein the level is provided with a weight portion and is biased so as to be in a horizontal posture by the weight portion. "
The machine tool of the present invention is summarized in (5).

(5) “In a machine tool provided with a tilting table tilted by a tilting mechanism,
A machine tool, wherein the table is a target for measuring the tilt angle, and the tilt angle measuring device according to any one of (1) to (4) is mounted as a device for measuring the tilt angle of the table. "
The gist of the tilt angle calibration method of the present invention is (6).

(6) “The inclination angle measuring device according to any one of (1) to (4) is attached to the table surface of the table so that the rotation axis of the rotary encoder is parallel to the rotation axis of the table, and the inclination A tilt angle calibration method for a machine tool, wherein the tilt angle of the table is calibrated based on the measurement result of the angle measuring device. "

In the tilt angle measuring apparatus of the present invention, since the level is coupled to the rotary shaft of the rotary encoder and the level is corrected horizontally by the actuator, accurate tilt angle measurement is possible.
According to the machine tool of the present invention, it is possible to work while detecting the tilt of the table with high accuracy by using the tilt angle measuring apparatus of the present invention.
According to the tilt angle calibration method of the present invention, it is possible to calibrate the indicated value of the tilt angle of the table with high accuracy by using the tilt angle measuring apparatus of the present invention.

  A first embodiment of the present invention will be described with reference to FIGS. In FIG. 1, reference numeral 5 denotes a table tilt type 5-axis control machining center, which includes a tilt table 51 tilted by a tilt mechanism. The control mechanism of the machine tool 5 can change the tilt angle θ by rotating the table 51 around the horizontal axis L1, and rotates around the axis L2 perpendicular to the table surface (the rotation angle is indicated by φ). ), The table surface can be rotated. In FIG. 1, the machining drill 52 is configured to be movable in the X, Y, and Z axes.

The main body of the tilt angle measuring apparatus 1 is fixed to the surface (table surface) of the table 51 that is the tilt angle measurement target in a direction parallel to the axis L1.
2 is an explanatory perspective view of the tilt angle measuring apparatus 1, and FIGS. 3A to 3D are a rear view, a right side view, a front view, and a left side view of the tilt angle measuring apparatus 1 when the table is tilted.
A rotary encoder 11, a level 12, a rotating shaft rotating mechanism 13, a rotating shaft rotating mechanism control device 14, a video camera 15, and a display 16 are provided. The rotary encoder 11 has a main body fixed to a tilt angle measurement target (table 51).

  In the present embodiment, the level 12 is a bubble tube level, and is attached integrally to the rotary shaft 111 of the rotary encoder 11. Further, in the present embodiment, the level 12 includes a weight 121, and the level 12 is urged by the weight 121 so as to be in a horizontal posture. 2 and 3A to 3D, the weight 121 is made of a metal plate having an inverted L-shaped cross section. 2 and 3A to 3D, the weight 121 is separated from the rotating shaft 111 so that it functions as a mounting jig for the level 12 and further the level 12 itself functions as a weight. It is attached to the position (downward).

The rotating shaft rotating mechanism 13 is configured to rotate the rotating shaft 111 so that the level 12 is in a horizontal posture. In the present embodiment, the rotary shaft rotating mechanism 13 is a rotary actuator (motor type, piezoelectric type, etc.), and includes a mechanism that directly acts on the rotary shaft 111 to rotate it. In FIG. 2 and FIGS. 3A to 3D, for convenience of explanation, the rotating shaft rotating mechanism 13 is shown separately from the rotary encoder 11.
The video camera 15 is photographing the level 12 and displays the level 12 on the display 16.

  In this embodiment, the rotation shaft rotation mechanism control device 14 can be configured as a part of the function of the computer. Based on the image of the level 12 displayed on the display 16, the operator can rotate the rotating shaft rotation mechanism control device 14 from the computer operation device (mouse, controller, keyboard, etc.) so that the level 12 is in a horizontal posture. Send instructions to. The rotation shaft rotation mechanism control device 14 generates a control amount corresponding to this instruction and sends it to the rotation shaft rotation mechanism 13.

  For example, when the table 51 is inclined at an angle θ, since the weight unit 121 is attached to the level 12, ideally the level 12 is in a horizontal posture, and the rotary encoder 11 sets θ as the inclination angle. Should output. However, in reality, the level 12 does not become horizontal due to frictional force between the rotary shaft 111 of the rotary encoder 11 and a bearing (not shown), etc. (the weight 121 does not face in the vertical direction). To do). That is, the rotary encoder 11 outputs θ−δ as an inclination angle.

In the present embodiment, the angle δ represents a measurement error. For example, when the resolution of the rotary encoder 11 is 0.0001 ° and the δ is about ± 1 °, the actual resolution of the rotary encoder 11 is about 1/1000. To drop.
In the present embodiment, according to the detection accuracy of the level 12, the angle δ can be detected with the accuracy. The measurement range required for the level 12 is only required to be operable within the range of δ. Since the measurement result by the level 12 is used only for horizontal detection, the level 12 is not required to have a function of outputting a deviation value as long as it has high sensitivity. That is, the accuracy and linearity of the level 12 do not affect the measurement accuracy of the entire tilt angle measuring device 1. Therefore, the tilt angle measuring apparatus 1 can measure the tilt angle with accuracy depending on the resolution of the rotary encoder 11.
In the present embodiment, the level 12 that can detect the inclination with high sensitivity is employed. Since the sensitivity of the level 12 can be equal to or higher than the resolution of the rotary encoder 11 (0.0001 ° in this example), the tilt angle measurement accuracy of the tilt angle measuring device 1 is the rotary encoder 11. Can be increased according to the resolution.

  As described above, the operator who is viewing the spirit level 12 gives an instruction from the operation device to the rotation shaft rotation mechanism control device 14 so that the level 12 is in a horizontal posture. Send instructions. The rotation shaft rotation mechanism control device 14 generates a control amount corresponding to this instruction and sends it to the rotation shaft rotation mechanism 13 so that the level 12 is in a horizontal posture. The rotating shaft 111 is rotated. Since the rotating shaft rotating mechanism 13 is driven so that the level 12 is in a horizontal posture, the accuracy of the rotation depends on the accuracy of the level 12.

  As described above, the tilt angle measurement value measured by the tilt angle measuring device 1 is used to calibrate the tilt angle by the control mechanism of the machine tool 5, that is, the tilt angle indicating values at a plurality of tilt angles are measured by the tilt angle measuring device 1. Adjustments can be made to match the measured tilt angle values.

A second embodiment of the present invention will be described with reference to FIG. 4 can be applied to the machine tool 5 shown in FIG.
In FIG. 4, the main body of the tilt angle measuring apparatus 2 is fixed to the surface (table surface) of the table 51 (see FIG. 1), which is the tilt angle measurement target, in a direction parallel to the axis L1.

  The tilt angle measuring device 2 includes a rotary encoder 21, an electronic level 22, a rotating shaft rotating mechanism 23, and a rotating shaft rotating mechanism control device 24. The rotary encoder 21 has a main body fixed to a tilt angle measurement target (table 51).

In the present embodiment, the level 22 is an electronic level and is integrally attached to the rotary shaft 211 of the rotary encoder 21. In the present embodiment, the level 22 includes a weight part 221, and the level 22 is urged by the weight part 221 so as to be in a horizontal posture.
The level 22 includes a level attitude detector 222 that detects the attitude and outputs attitude information.
The rotating shaft rotating mechanism 23 rotates the rotating shaft 211 so that the level 22 is in a horizontal posture, like the rotating shaft rotating mechanism 13 shown in FIGS. 2 and 3A to 3D. It is configured. The rotating shaft rotating mechanism 23 of the present embodiment is a rotary actuator (motor type, piezoelectric type, etc.), like the rotating shaft rotating mechanism 13 of the first embodiment. The rotating shaft rotating mechanism 23 can rotate the rotating shaft based on the posture information from the level indicator posture detector 222.
In this embodiment, the rotary shaft rotation mechanism control device 24 is attached to the frame of the rotary encoder 21.
As in the first embodiment, when the table 51 is inclined at an angle θ, the level 22 is ideally in a horizontal posture, and the rotary encoder 21 should output θ as the inclination angle. However, in reality, the level 22 is stationary in a posture that does not become a horizontal posture due to frictional force between the rotary shaft 211 of the rotary encoder 21 and a bearing (not shown), and the rotary encoder 21 sets θ−δ as an inclination angle. Output.

  As in the case of the first embodiment, the angle δ represents a measurement error. For example, if the resolution of the rotary encoder 21 is 0.0001 ° and δ is about ± 1 °, the actual resolution of the rotary encoder 21 is It drops to about 1/1000.

  Also in this embodiment, according to the detection accuracy of the level 22, the angle δ can be detected with the accuracy, and the measurement range required for the level 22 may be anything that can operate within the range of δ. Since the measurement result by the level 22 is used only for horizontal detection, the level 22 is not required to have a function of outputting a deviation value as long as it has high sensitivity. Therefore, the tilt angle measuring device 2 can measure the tilt angle with accuracy depending on the resolution of the rotary encoder 21.

  In the present embodiment, the level 22 is an electronic type, and can output information on whether or not it is deviated from the horizontal with high sensitivity and in which direction around the rotation axis (for example, 0.0001). Can sense tilt of °). Since the sensitivity of the level 22 can be equal to or higher than the resolution of the rotary encoder 21 (0.0001 ° in this example), the tilt angle measurement accuracy of the tilt angle measuring device 2 is the rotary encoder 21. Can be increased according to the resolution.

  Attitude information is sent from the level detector attitude detector 222 of the level 22 to the rotation axis rotation mechanism control device 24, and the rotation axis rotation mechanism control device 24 generates a control amount corresponding to the attitude information, Is sent to the rotating shaft rotating mechanism 23, and the rotating shaft rotating mechanism 23 rotates the rotating shaft 211 so that the level 22 is in a horizontal posture. Since the rotary shaft rotation mechanism 23 is driven so that the level 22 is in a horizontal posture, the accuracy of the rotation depends on the accuracy of the level 22.

As described above, the tilt angle measurement value measured by the tilt angle measuring device 2 is used to calibrate the tilt angle by the control mechanism of the machine tool 5, that is, the tilt angle indicating values at a plurality of tilt angles are measured by the tilt angle measuring device 2. Adjustments can be made to match the measured tilt angle values. In FIG. 2, the output result of the rotary encoder 21 is configured to be sent to the computer PC.
Note that the machine tool 5 can be configured such that the table 51 of the machine tool 5 shown in FIG. 1 is mounted (coupled) with the tilt angle measuring device 2 so that the machine tool can be machined while measuring the tilt angle.

"Test results"
As the processing machine 5 shown in FIG. 1, a table turning type 5-axis control machining center was used, and a positioning accuracy test of the inclined axis L1 was performed according to JISB6192.
The axis L1 was positioned 5 degrees between 0 ° and 90 °, and measurements were taken for 5 reciprocations while being horizontally adjusted at each angle. The positioning accuracy and repeatability (reproducibility) were evaluated from the target angle for positioning every 5 ° and the actual tilt angle measured by the rotary encoder 11 or 21. The measurement / evaluation results at this time are shown in FIGS.
As shown in FIG. 5A, there is a difference in the deviation between going and returning due to the influence of backlash existing in the drive mechanism of the shaft L1. FIG. 5A shows the standard deviation of the measurement results at each measured angle.
As shown in FIG. 5 (B), the measurement result varies due to the influence of the error of the measuring instrument itself and the error, but this variation was 3 ″ or less, no matter how badly estimated.

It is explanatory drawing which shows the machine tool used by embodiment of this invention. It is explanatory drawing of the inclination-angle measuring apparatus which shows 1st Embodiment of this invention. (A) is a rear view when the table of the tilt angle measuring device is tilted, (B) is a right side view, (C) is a front view, and (D) is a left side view. It is explanatory drawing of the inclination-angle measuring apparatus which shows 2nd Embodiment of this invention. (A), (B) is a graph which shows the test result of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inclination angle measuring device 5 Machine tool 11, 21 Rotary encoder 12, 22 Level 13, 23 Rotating shaft rotating mechanism 14, 24 Rotating shaft rotating mechanism control device 15 Video camera 16 Display 51 Inclining table 111, 211 Rotating shaft 121 , 221 Weight 222 Level sensor attitude detector θ Inclination angle L1 θ axis L2 φ axis

Claims (7)

A rotary encoder whose main body is fixed to the tilt angle measurement target;
A level attached to the rotary shaft of the rotary encoder and rotating integrally with the rotary shaft;
A rotating shaft rotating mechanism that rotates the rotating shaft so that the level is in a horizontal posture;
An inclination angle measuring device comprising:   2. The level device according to claim 1, wherein the level device includes a level device posture detector that detects posture and outputs posture information, and the rotation shaft rotation mechanism rotates the rotation shaft based on the posture information. The tilt angle measuring device described.   2. The level device according to claim 1, wherein the level device includes a level device posture detector that detects posture and outputs posture information, and the rotation shaft rotation mechanism rotates the rotation shaft based on the posture information. The tilt angle measuring device described.   The inclination level measuring device according to any one of claims 1 to 3, wherein the spirit level includes a weight part and is biased so as to be in a horizontal posture by the weight part. In a machine tool equipped with a tilting table tilted by a tilting mechanism,
A machine tool, wherein the table is a target for measuring the tilt angle, and the tilt angle measuring device according to any one of claims 1 to 4 is mounted as a device for measuring the tilt angle of the table. In a tilt angle calibration method for a machine tool having a tilt table tilted by a tilt mechanism,
5. The tilt angle calibration method for a machine tool, wherein the table is the tilt angle measurement object, and the tilt angle of the table is calibrated using the tilt angle measuring device according to claim 1. . The tilt angle measuring device according to any one of claims 1 to 4 is attached to a table surface of the table so that a rotary shaft of the rotary encoder is parallel to a rotary shaft of the table, and a measurement result of the tilt angle measuring device A tilt angle calibration method for a machine tool, wherein the tilt angle of the table is calibrated based on the method.

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