Calibration device and calibration method for center point of rotating shaft of five-axis numerical control machine tool

Abstract

The invention discloses a calibration device and a five-axis numerical control machine tool rotating shaft center point calibration method, and belongs to the technical field of five-axis numerical control machine tool precision calibration. The calibration device comprises a ball head detection rod, a clamp, a first measuring device and a second measuring device, the clamp is used for being installed on a workbench of a machine tool and comprises a first clamping arm and a second clamping arm, the first clamping arm clamps one of the first measuring device and the second measuring device, and the second clamping arm clamps the other one of the first measuring device and the second measuring device. The second clamping arm clamps the other one of the first measuring device and the second measuring device, and the ball head detection rod comprises a rod body and a ball body. After the calibration device is installed at the corresponding position of the machine tool, the measured values of the first measuring device and the second measuring device can be used for calibrating the center of the rotating shaft to be measured of the machine tool. Compared with the prior art in which measurement is carried out through a dial indicator, the error of the center of the rotating shaft can be analyzed more accurately through data in the two-dimensional plane, so that the calibration precision of the center of the rotating shaft is improved.

Description

Technical Field

[0001] The present application belongs to the technical field of precision calibration of five-axis CNC machine tools, and specifically relates to a calibration device and a method for calibrating the center point of a rotating axis of a five-axis CNC machine tool. Background Art

[0002] A five-axis CNC machine tool is a machine tool that has at least three moving axes (x, y, and z) plus any two rotating axes, and can perform coordinated movements under the control of a computer numerical control (CNC) system. It is generally used in the fields of aviation, aerospace, military, and high-precision medical equipment.

[0003] In order to ensure the machining accuracy of the five-axis CNC machine tool, it is necessary to calibrate the centers of the two rotating axes of the machine tool. In the related technology, a ball head check rod and a single micrometer are used for calibration. The first step is to install the ball head check rod on the tool holder and the micrometer on the workbench, and read the first value of the micrometer measuring the target position of the ball head check rod (any position on the sphere of the ball head check rod); the second step is to read the second value of the micrometer measuring the target position of the ball head check rod after the rotating axis moves to the preset position; the third step is to calibrate the coordinates of the center of the rotating axis according to the first value and the second value.

[0004] Since at least one rotating axis of a five-axis CNC machine tool has a travel limitation and cannot rotate 360°, and the micrometer measurement in the above method is a one-dimensional measurement, there will be theoretical errors, resulting in low accuracy of the above calibration method. Summary of the invention

[0005] The purpose of the embodiments of the present application is to provide a calibration device and a calibration method for the center point of the rotation axis of a five-axis CNC machine tool, which can solve the problem of low calibration accuracy of the center point of the rotation axis of a current five-axis CNC machine tool.

[0006] In a first aspect, an embodiment of the present application provides a calibration device, the calibration device comprising a ball-end test rod, a fixture, a first measuring device and a second measuring device, the fixture being used to be installed on a workbench of a machine tool, the fixture comprising a first clamping arm and a second clamping arm, the first clamping arm clamping one of the first measuring device and the second measuring device, the second clamping arm clamping the other of the first measuring device and the second measuring device, the ball-end test rod comprising a rod body and a sphere;

[0007] Wherein, when the rod body is installed on the tool holder of the machine tool, the sphere is arranged at the end of the rod body away from the tool holder, the first measuring device is used to measure a first point on the sphere, and the second measuring device is used to measure a second point on the sphere; the measurement values ​​obtained by the first measuring device measuring the first point and the second measuring device measuring the second point can be used to calibrate the rotation axis center of the rotation axis to be measured of the machine tool.

[0008] In a second aspect, an embodiment of the present application provides a method for calibrating the center point of a rotation axis of a five-axis CNC machine tool, which is applied to the calibration device as described in the first aspect, and the method includes:

[0009] When the calibration device is installed on a machine tool and the rotation axis to be measured of the machine tool is located at an initial position, obtaining a first array obtained by measurement based on the first measuring device and / or the second measuring device;

[0010] When the rotating shaft to be measured rotates by a preset angle, obtaining a second array measured by the first measuring device and / or the second measuring device;

[0011] Adjusting the position of the center of the rotation axis of the machine tool based on the first array and the second array until a third array and a fourth array measured by the first measuring device and / or the second measuring device meet a preset condition;

[0012] The third array is an array measured by the first measuring device and the second measuring device when the measured rotating axis is rotated back to the initial position after adjusting the position of the center of the rotating axis;

[0013] The fourth array is an array measured by the first measuring device and the second measuring device when the measured rotating axis is first rotated back to the initial position and then rotated by the preset angle after adjusting the position of the center of the rotating axis;

[0014] The preset conditions include:

[0015] The difference between the third array and the fourth array is smaller than a preset value.

[0016] In an embodiment of the present application, the calibration device includes a ball-end test rod, a fixture, a first measuring device and a second measuring device, the fixture is used to be installed on a workbench of a machine tool, the fixture includes a first clamping arm and a second clamping arm, the first clamping arm clamps one of the first measuring device and the second measuring device, and the second clamping arm clamps the other of the first measuring device and the second measuring device, the ball-end test rod includes a rod body and a sphere; wherein, when the rod body is installed on a tool holder of the machine tool, the sphere is arranged at an end of the rod body away from the tool holder, the first measuring device is used to measure a first point on the sphere, and the second measuring device is used to measure a second point on the sphere; the measurement values ​​obtained by the first measuring device measuring the first point and the second measuring device measuring the second point can be used to calibrate the rotation axis center of the rotation axis to be measured of the machine tool. The ball head inspection rod is measured by the first measuring device and the second measuring device to realize two-dimensional measurement. The obtained measurement data is data in a two-dimensional plane constituted by the direction corresponding to the first measuring device and the direction corresponding to the second measuring device. Compared with the method of measuring by only one micrometer in the prior art, the method of the embodiment of the present application can accurately analyze the error of the center of the rotating axis through the data in the two-dimensional plane, and calibrate the center of the rotating axis according to the more accurate error, thereby improving the calibration accuracy of the center of the rotating axis. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0018] Figure 1 One of the assembly schematic diagrams of the calibration device provided in the embodiment of the present application;

[0019] Figure 2 The second assembly diagram of the calibration device provided in the embodiment of the present application;

[0020] Figure 3 A schematic diagram of assembling the fixture, the first measuring device and the second measuring device provided in an embodiment of the present application;

[0021] Figure 4 A schematic diagram of the assembly of a clamping arm clamping measuring device provided in an embodiment of the present application;

[0022] Figure 5 One of the scene schematic diagrams of the tool front end point following characteristics provided in the embodiment of the present application;

[0023] Figure 6 The second schematic diagram of the scene of the tool front end point following characteristic provided in the embodiment of the present application;

[0024] Figure 7 This is a schematic diagram of measurement error when using a single micrometer for measurement;

[0025] Figure 8 A schematic diagram of the steps of the calibration method provided in an embodiment of the present application;

[0026] Fig. 9 One of the operation interface schematic diagrams provided in the embodiment of the present application;

[0027] Fig.10 The second schematic diagram of the operation interface provided in the embodiment of the present application;

[0028] Fig.11 The third schematic diagram of the operation interface provided in the embodiment of the present application;

[0029] Fig.12 One of the schematic diagrams of the calibration principle for a rotating axis with a rotation range less than 360° provided in an embodiment of the present application;

[0030] Fig.13 The second schematic diagram of the calibration principle for a rotating axis with a rotation range less than 360° provided in an embodiment of the present application;

[0031] Fig.14 The fourth schematic diagram of the operation interface provided in the embodiment of the present application;

[0032] Fig.15 A schematic diagram of the calibration principle for a rotating shaft with a rotation range of 360° provided in an embodiment of the present application;

[0033] Fig.16 A schematic diagram of the principle of the theoretical error of the calibration method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present application to clearly describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments in the present application belong to the scope of protection of this application.

[0035] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0036] like Figures 1 to 4 As shown, the calibration device provided in the embodiment of the present application includes: a ball head test rod, a clamp, a first measuring device and a second measuring device, the clamp is used to be installed on the workbench of a machine tool, the clamp includes a first clamping arm and a second clamping arm, the first clamping arm clamps one of the first measuring device and the second measuring device, the second clamping arm clamps the other of the first measuring device and the second measuring device, and the ball head test rod includes a rod body and a sphere.

[0037] When the rod body is installed on the tool holder of the machine tool, the sphere is arranged at the end of the rod body away from the tool holder, the first measuring device is used to measure a first point on the sphere, and the second measuring device is used to measure a second point on the sphere; the measurement values ​​obtained by the first measuring device measuring the first point and the second measuring device measuring the second point can be used to calibrate the rotation axis center of the rotation axis to be measured of the machine tool.

[0038] In the present application, the rotation axis center of the rotation axis to be measured refers to the rotation center of the rotation axis to be measured when it rotates.

[0039] In such Figures 1 to 4 In the illustrated embodiment, the first measuring device and the second measuring device use the same device, which is a micrometer. In actual application, the first measuring device and the second measuring device can select the same or different existing measuring devices according to actual conditions.

[0040] The first clamping arm clamps the first measuring device, and the second clamping arm clamps the second measuring device. The first clamping arm and the second clamping arm have the same structure, and only have different setting directions. Figure 3 In the illustrated embodiment, the arrangement direction of the first clamping arm and the arrangement direction of the second clamping arm are perpendicular to each other.

[0041] Optionally, the first clamping arm and the second clamping arm are made of aluminum alloy, which can ensure that the first clamping arm and the second clamping arm have sufficiently high rigidity. Figure 4In the illustrated embodiment, a clamping groove is provided on the second clamping arm, and a mounting frame of the second measuring device is arranged in the clamping groove and is locked by bolts. It should be noted that the mounting frame of a general measuring device, such as a dial gauge frame, cannot ensure sufficient rigidity. When the dial gauge is tilted, the dial gauge will produce a large deformation, which will reduce the measurement accuracy of the dial gauge, and the error can reach more than 0.07mm. However, after being clamped by the clamping arm with higher rigidity in this embodiment, it can be ensured that the measuring device is not affected by gravity at any measuring angle and posture, thereby improving the measurement accuracy, and also improving the calibration accuracy of the center of the rotating axis.

[0042] After the ball head inspection rod is installed on the tool holder of the machine tool, the first measuring device is used to measure the first point, and the second measuring device is used to measure the second point, which can form an array. When the rotating axis to be measured rotates to multiple different angles, multiple arrays can be obtained through the measurement of the first measuring device and the second measuring device. Through these multiple arrays, the position of the center of the rotating axis of the rotating axis to be measured can be analyzed and calibrated.

[0043] like Figure 5 and Figure 6 As shown, the five-axis CNC machine tool has the following tool tip point following characteristics: In the five-axis CNC machine tool, when the tool tip point control function is used to indicate the rotation axis command alone, the position of the tool tip point relative to the workbench can be kept unchanged according to the position of the machine tool rotation axis. In other words, whether the rotation axis to be measured is in the initial position or in different positions after rotating to different angles, although the posture of the corresponding workbench will change when the rotation axis to be measured rotates to different positions, the position of the tool tip point relative to the position of the workbench remains unchanged. It can be understood that in the embodiment of the present application, the spherical test rod replaces the tool, and the measurement of the sphere of the spherical test rod by the first measuring device and the second measuring device can be equivalent to the measurement of the tool tip point. When the rotating axis to be measured rotates to multiple different angles, although the posture of the workbench will change (for example, the workbench 51 (A) is driven to rotate by its corresponding rotating axis or the workbench 51 (B) is driven to rotate by its corresponding rotating axis), the values ​​of the multiple arrays obtained by measuring the first measuring device and the second measuring device should remain unchanged. If a change occurs, it means that there is a deviation between the position of the rotating axis center currently set to the rotating axis to be measured and the actual rotating axis center. The deviation can be calculated based on the multiple arrays and corresponding adjustments can be made.

[0044] In order to clarify the difference between the calibration of the center of the rotation axis using the calibration device of the embodiment of the present application and the existing calibration method, the existing calibration method is now described as follows:

[0045] like Figure 7As shown, the existing calibration method is to use a micrometer to measure the ball head test rod. At angles A90, A-90, and A0, although the readings measured by the micrometer are the same, the rotation center of the rotating axis to be measured is actually different from the center of the ball of the ball test rod, but this problem has not been noticed. In other words, if the rotation stroke of the rotating axis to be measured is not 360°, for example, the micrometer can only measure within the range of 0-90° and cannot achieve full rotation range measurement, the theoretical error cannot be detected, resulting in a reduction in calibration accuracy.

[0046] In an embodiment of the present application, the ball head test rod is measured by a first measuring device and a second measuring device to achieve two-dimensional measurement. The obtained measurement data is data in a two-dimensional plane constituted by the direction corresponding to the first measuring device and the direction corresponding to the second measuring device. Compared with the method of measuring by only one micrometer in the prior art, the method of the embodiment of the present application can accurately analyze the error of the center of the rotating axis through the data in the two-dimensional plane, and calibrate the center of the rotating axis according to the more accurate error, thereby improving the calibration accuracy of the center of the rotating axis.

[0047] Optionally, the clamp further includes a support frame and a magnetic base, the magnetic base is used to be adsorbed on the workbench, the support frame is arranged on the magnetic base, and the first clamping arm and the second clamping arm are installed on the support frame.

[0048] like Figure 2 and Figure 3 As shown, the clamp includes a support frame and a magnetic base connected to each other. The magnetic base is mounted on the workbench by magnetism, and no other equipment is required for auxiliary installation, which is easy to operate. The two sides of the support frame are respectively used to connect the first clamping arm and the second clamping arm. The structure is simple, easy to produce, and low in cost.

[0049] Optionally, a weight-reducing groove is provided on the support frame, and the weight-reducing groove is used to reduce the weight of the entire clamp, so as to facilitate the use of the operator.

[0050] Optionally, the weight-reducing groove includes a first weight-reducing groove and a second weight-reducing groove, the first weight-reducing groove is located at the connection between the first clamping arm and the support frame, and the second weight-reducing groove is located at the connection between the second clamping arm and the support frame.

[0051] like Figure 3 As shown, the first weight reducing groove and the second weight reducing groove are respectively opened in the area on the support frame for connecting the first clamping arm and the second clamping arm, which further expands the range of the weight reducing groove. Combined with the first clamping arm, the second clamping arm and the support frame are made of aluminum alloy, the weight of the clamp is further reduced, which is convenient for operators to use.

[0052] The present application also provides a method for calibrating the center point of a five-axis CNC machine tool rotation axis, which can be applied to Figures 1 to 4 The calibration device shown in the embodiment, such as Figure 8 As shown, the calibration method comprises the following steps:

[0053] Step 101 : when the calibration device is installed on a machine tool and a rotating axis to be measured of the machine tool is located at an initial position, a first array obtained by measurement based on the first measuring device and / or the second measuring device is obtained.

[0054] Before calibration, you need to set the initial coordinates of the center of the rotation axis to be measured. Fig. 9 Set up in the interface shown in the figure, and enter the values ​​of "X-axis mechanical coordinate of point P, Y-axis mechanical coordinate of point P, Z-axis mechanical coordinate of point P, X-axis coordinate offset from point P to point Q, Y-axis coordinate offset from point P to point Q, Z-axis coordinate offset from point P to point Q, and ΔT tool holder offset" according to the design data or historical measurement data.

[0055] The state of the calibration device installed on the machine tool is that the fixture is installed on the workbench, the first clamping arm clamps the first measuring device, the second clamping arm clamps the second measuring device, the rod is installed on the tool holder of the machine tool, the sphere is set at the end of the rod away from the tool holder, the first measuring device is used to measure the first point on the sphere, and the second measuring device is used to measure the second point on the sphere. When installing the calibration device, it is necessary to set the tool compensation value and the workpiece coordinate system to initialize the machine tool. In this embodiment, a ball-end test rod is used instead of a tool, so the tool compensation value is set with the center position of the sphere as a reference. This can be done by Fig.10 Enter the corresponding parameters in the interface shown to set the tool compensation value ( Fig.10 Tool offset), workpiece coordinate system.

[0056] After completing the above preparations before calibration, the first array can be obtained by reading the readings of the first measuring device and / or the second measuring device.

[0057] Step 102: when the rotation axis to be measured rotates by a preset angle, obtain a second array obtained based on measurements of the first measuring device and / or the second measuring device.

[0058] After reading the first array, the rotation axis to be measured is manipulated to rotate a preset angle, and the second array can be obtained by reading the readings of the first measuring device and / or the second measuring device. Fig.11In the interface shown, the Y-axis representation number and the Z-axis representation number corresponding to the calibration angle 1 are the measured values ​​of the first measuring device and the second measuring device when the rotating axis to be measured is in the initial position; the Y-axis representation number and the Z-axis representation number corresponding to the calibration angle 2 are the measured values ​​of the first measuring device and the second measuring device when the rotating axis to be measured rotates by a preset angle.

[0059] Step 103, adjusting the position of the center of the rotation axis of the machine tool based on the first array and the second array, until a third array and a fourth array measured by the first measuring device and / or the second measuring device meet a preset condition;

[0060] The third array is an array measured by the first measuring device and the second measuring device when the measured rotating axis is rotated back to the initial position after adjusting the position of the center of the rotating axis;

[0061] The fourth array is an array measured by the first measuring device and the second measuring device when the measured rotating axis is first rotated back to an initial position and then rotated by the preset angle after adjusting the position of the center of the rotating axis.

[0062] The preset conditions include:

[0063] The difference between the third array and the fourth array is smaller than a preset value.

[0064] Please see further Fig.11 In the interface shown, after inputting the data of the first array and the second array, the operator clicks on calculate compensation, and the computer automatically calculates the compensation value, and adjusts the initial position of the center of the rotation axis according to the compensation value. Then, the third array and the fourth array are obtained in a similar manner to the first array and the second array, and the compensation value of the center of the rotation axis is calculated based on the third array and the fourth array, and the position of the center of the rotation axis is adjusted. The above process of obtaining arrays and adjusting the position of the center of the rotation axis according to the arrays is repeated until the difference between the third array and the fourth array is less than the preset value. It can be understood that although theoretically there is no difference between the third value and the fourth value, indicating that the position of the center of the rotation axis is accurate, there will be errors in actual application anyway. Therefore, as long as the difference between the third array and the fourth array is less than the preset value, it can be determined that the position of the center of the rotation axis is accurate.

[0065] In the calibration method of the embodiment of the present application, the ball head test rod is measured by the first measuring device and the second measuring device to achieve two-dimensional measurement. The obtained measurement data is the data in the two-dimensional plane formed by the direction corresponding to the first measuring device and the direction corresponding to the second measuring device. Compared with the method of measuring by only one micrometer in the prior art, the theoretical error can be analyzed by the data in the two-dimensional plane, thereby improving the calibration accuracy of the rotation axis center. In addition, the present application also provides such Figures 9 to 11 The interface shown has automatic operation steps guidance and diagrams, so that the measurement can be completed correctly without referring to the manual or being proficient. Different measurement programs are automatically generated according to the machine tool structure and stroke, and are applicable to all five-axis machine tools with orthogonal rotating axis structures. According to the measurement value input by the operator, the algorithm is called for automatic compensation, reducing human operation and repeated adjustments.

[0066] Optionally, the first line and the second line are perpendicular to each other, wherein the first line is a line between the first point and the center of the sphere, and the second line is a line between the second point and the center of the sphere. A third line between the first point and the center of the first measuring device is perpendicular to the rotation plane of the measured rotation axis, and a fourth line between the second point and the center of the second measuring device is parallel to the rotation plane of the measured rotation axis. In this embodiment, the first point and the second point are the highest points of the respective corresponding measuring devices in the measuring direction.

[0067] Optionally, when the rotation stroke of the rotating shaft to be measured is less than 360°, the preset angle is 90°;

[0068] The first array includes: when the measured rotating axis is located at the initial position, a first measurement value of the first point measured by the first measuring device and a second measurement value of the second point measured by the second measuring device;

[0069] The second array includes: a third measurement value of the first point measured by the first measuring device and a fourth measurement value of the second point measured by the second measuring device after the measured rotation axis rotates 90°;

[0070] The adjusting the position of the center of the rotation axis based on the first array and the second array comprises:

[0071] Based on the first array and the second array, determine a first deviation value of the center of the sphere in a first direction and a second deviation value of the center of the sphere in a second direction, wherein the first direction is a direction of a line between the first point and the center of the first measuring device, and the second direction is a direction of a line between the second point and the center of the second measuring device;

[0072] Based on the first deviation value and the second deviation value, determining a first calibration parameter of the rotation axis center of the rotation axis to be measured in the first direction and a second calibration parameter of the rotation axis center in the second direction, wherein the value of the first calibration parameter is half of a first target value, the first target value is a difference between the first deviation value and the second deviation value, and the value of the second calibration parameter is consistent with an average of the first deviation value and the second deviation value;

[0073] The position of the center of the rotation axis is adjusted based on the first calibration parameter and the second calibration parameter.

[0074] Optionally, the first deviation value is the difference between the second measurement value and the fourth measurement value, and the second deviation value is the difference between the third measurement value and the first measurement value.

[0075] The rotation axis to be tested in this embodiment is a rotation axis with a rotation stroke less than 360°, for example Figure 1 The workbench 51 (B) shown in FIG. Fig.11 The rotating axis to be measured in the embodiment shown is a rotating axis with a rotation range of less than 360°. In this case, the preset angle is 90°, and the first array and the second array both include the readings of the first measuring device and the second measuring device.

[0076] The calculation principle of the first calibration parameter and the second calibration parameter for a rotation axis with a rotation stroke less than 360° is explained by the following example:

[0077] The first measuring device and the second measuring device are a Y-axis micrometer and a Z-axis micrometer respectively. Fig.12 and Fig.13 As shown, by reading the readings of the micrometer in the YZ direction at A0 and A-90, the deviation of the ball position can be obtained, and the deviation of the rotation center can be calculated based on the deviation. In this way, the problem can be simplified to the geometric problem in the figure below: Two 90-degree arcs, with the same starting point a and a known end point deviation vector In the case of (in and The length is much smaller than the arc radius R).

[0078] Assume the positions of point a and point b are:

[0079] Let point p be the midpoint between a and b, for The perpendicular bisector of . The coordinates of point p are expressed as:

[0080]

[0081] Since point d is the center of the circle and ad and bd are perpendicular, we know that the lengths of line segments ad and bd are equal. The vector is If the vector is rotated 90 degrees clockwise, then The vector is:

[0082]

[0083] Calculate the coordinates of the center point d of arc ab as:

[0084]

[0085] Set vector

[0086] Assume that the position of point c is (Yb+Ym Zb+Zm). According to the calculation formula of the center of the circle, the coordinates of point e, the center of the arc ac, are:

[0087]

[0088] Then the vector for:

[0089]

[0090] Assume that the measured values ​​of the YZ micrometer are as follows:

[0091]

[0092] Then the deviation position of the sphere center can be calculated:

[0093] Ym=m2-m4.

[0094] Zm=m3-m1.

[0095] The A-axis center point compensation formula is:

[0096]

[0097]

[0098] Among them, Ym is the first deviation value, Zm is the second deviation value, ΔY 补A is the first calibration parameter, ΔZ 补A The first calibration parameter and the second calibration parameter can be used to measure the deviation between the actual position of the center point of the rotating axis and the set value, thereby completing the compensation of the rotating axis to be measured.

[0099] Optionally, when the rotation stroke of the rotating shaft to be measured is 360°, the preset angles include at least 90°, 180° and 270°;

[0100] The first array includes: when the rotation axis to be measured is located at the initial position, the first measuring device measures a fifth measurement value of the first point position;

[0101] The second array includes:

[0102] After the rotation axis to be measured rotates 90°, the first measuring device measures a sixth measurement value of the first point;

[0103] After the rotation axis to be measured rotates 180°, the first measuring device measures a seventh measurement value of the first point;

[0104] After the rotation axis to be measured rotates 270°, the first measuring device measures an eighth measurement value of the first point;

[0105] The adjusting the position of the center of the rotation axis based on the first array and the second array comprises:

[0106] Based on the first array and the second array, determining a third calibration parameter of the rotation axis center of the rotation axis to be measured in the first direction and a fourth calibration parameter of the rotation axis center in the second direction;

[0107] adjusting the position of the center of the rotation axis based on the third calibration parameter and the fourth calibration parameter;

[0108] Among them, the first direction is the direction of the line between the first point and the center of the first measuring device, the second direction is the direction of the line between the second point and the center of the second measuring device, the value of the third calibration parameter is half of the second target value, the second target value is the difference between the sixth measurement value and the eighth measurement value, and the value of the fourth calibration parameter is half of the third target value, and the third target value is the difference between the fifth measurement value and the seventh measurement value.

[0109] The rotation axis to be tested in this embodiment is a rotation axis with a rotation range of 360°, for example Fig.15 The workbench 51 (A) shown in FIG. Fig.14 The rotating axis to be measured in the embodiment shown is a rotating axis with a rotation range of less than 360°. In this case, the preset angles are 90°, 180°, and 270° (ie -90°), and the first array and the second array only include the readings of the first measuring device.

[0110] The calculation principle of the first calibration parameter and the second calibration parameter of the rotation axis to be measured with a rotation stroke of 360° is explained by the following example:

[0111] The rotating axis to be measured is located at the four quadrant points C0, C90, C180, and C270, and the readings of the Y micrometer (the first measuring device) are read.

[0112] Assume that the measured values ​​of the Y micrometer are as follows:

[0113]

[0114] According to the difference between the measurement results of the respective limit points of C0 and C180, C90 and C270, the center point deviation data formula can be easily obtained:

[0115]

[0116] ΔX 补C is the third calibration parameter, ΔY 补C The fourth calibration parameter can be used to measure the deviation between the actual position of the center point of the rotating axis and the set value, thereby completing the compensation of the rotating axis.

[0117] It should be noted that there is an inherent error in the calibration method of the embodiment of the present application, such as Fig.16 As shown, there may be a distance Δs between the contact point between the micrometer and the spherical surface and the highest point in the measurement direction of the micrometer, resulting in a measurement error e.

[0118] According to theoretical calculations, the relationship between Δs and e is as follows (sphere radius 15 mm):

[0119] Δs(mm) e(mm) 0.1 0.00033 0.2 0.00133 0.3 0.003 0.4 0.00533 0.5 0.00834

[0120] It can be seen that if a significant measurement error (>0.005mm) occurs, the center point has deviated by more than 0.4mm in the horizontal direction, and the horizontal sheet deviation becomes the main error. After compensation, it can be significantly reduced to within 0.1mm. If measured again, the error e is less than 0.0003mm. Therefore, in the method of the embodiment of the present application, after adjusting a single rotating axis to be measured 2 times or more, the final result is taken as the final result when the final reading remains unchanged, which can eliminate the influence of the error.

[0121] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0122] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A calibration device, characterized in that: The calibration device comprises a ball-end test rod, a fixture, a first measuring device and a second measuring device, wherein the fixture is used to be installed on a workbench of a machine tool, the fixture comprises a first clamping arm and a second clamping arm, the first clamping arm clamps one of the first measuring device and the second measuring device, and the second clamping arm clamps the other of the first measuring device and the second measuring device, and the ball-end test rod comprises a rod body and a sphere; Wherein, when the rod body is installed on the tool holder of the machine tool, the sphere is arranged at the end of the rod body away from the tool holder, the first measuring device is used to measure a first point on the sphere, and the second measuring device is used to measure a second point on the sphere; the measurement values ​​obtained by the first measuring device measuring the first point and the second measuring device measuring the second point can be used to calibrate the rotation axis center of the rotation axis to be measured of the machine tool.

2. The calibration device according to claim 1, characterized in that The clamp also includes a support frame and a magnetic base, the magnetic base is used to be adsorbed on the workbench, the support frame is arranged on the magnetic base, and the first clamping arm and the second clamping arm are installed on the support frame.

3. The calibration device according to claim 2, characterized in that The support frame is provided with a weight-reducing groove.

4. The calibration device according to claim 3, characterized in that The weight-reducing groove comprises a first weight-reducing groove and a second weight-reducing groove, wherein the first weight-reducing groove is located at the connection between the first clamping arm and the support frame, and the second weight-reducing groove is located at the connection between the second clamping arm and the support frame.

5. A method for calibrating the center point of a rotating axis of a five-axis CNC machine tool, applied to a calibration device as claimed in any one of claims 1 to 4, characterized in that: The method comprises: When the calibration device is installed on a machine tool and the rotation axis to be measured of the machine tool is located at an initial position, obtaining a first array obtained by measurement based on the first measuring device and / or the second measuring device; When the rotating shaft to be measured rotates by a preset angle, obtaining a second array measured by the first measuring device and / or the second measuring device; Adjusting the position of the center of the rotation axis of the machine tool based on the first array and the second array until a third array and a fourth array measured by the first measuring device and / or the second measuring device meet a preset condition; The third array is an array measured by the first measuring device and the second measuring device when the measured rotating axis is rotated back to the initial position after adjusting the position of the center of the rotating axis; The fourth array is an array measured by the first measuring device and the second measuring device when the measured rotating axis is first rotated back to the initial position and then rotated by the preset angle after adjusting the position of the center of the rotating axis; The preset conditions include: The difference between the third array and the fourth array is smaller than a preset value.

6. The method according to claim 5, characterized in that When the rotation stroke of the rotating shaft to be measured is less than 360°, the preset angle is 90°; The first array includes: when the measured rotating axis is located at the initial position, a first measurement value of the first point measured by the first measuring device and a second measurement value of the second point measured by the second measuring device; The second array includes: a third measurement value of the first point measured by the first measuring device and a fourth measurement value of the second point measured by the second measuring device after the measured rotation axis rotates 90°; The adjusting the position of the center of the rotation axis based on the first array and the second array comprises: Based on the first array and the second array, determine a first deviation value of the center of the sphere in a first direction and a second deviation value of the center of the sphere in a second direction, wherein the first direction is a direction of a line between the first point and the center of the first measuring device, and the second direction is a direction of a line between the second point and the center of the second measuring device; Based on the first deviation value and the second deviation value, determining a first calibration parameter of the rotation axis center of the rotation axis to be measured in the first direction and a second calibration parameter of the rotation axis center in the second direction, wherein the value of the first calibration parameter is half of a first target value, the first target value is a difference between the first deviation value and the second deviation value, and the value of the second calibration parameter is consistent with an average of the first deviation value and the second deviation value; The position of the center of the rotation axis is adjusted based on the first calibration parameter and the second calibration parameter.

7. The method according to claim 6, characterized in that The method further comprises: The first deviation value is the difference between the second measurement value and the fourth measurement value, and the second deviation value is the difference between the third measurement value and the first measurement value.

8. The method according to claim 5, characterized in that When the rotation stroke of the rotating shaft to be measured is 360°, the preset angles include at least 90°, 180° and 270°; The first array includes: when the rotation axis to be measured is located at the initial position, the first measuring device measures a fifth measurement value of the first point position; The second array includes: After the rotation axis to be measured rotates 90°, the first measuring device measures a sixth measurement value of the first point; After the rotation axis to be measured rotates 180°, the first measuring device measures a seventh measurement value of the first point; After the rotation axis to be measured rotates 270°, the first measuring device measures an eighth measurement value of the first point; The adjusting the position of the center of the rotation axis based on the first array and the second array comprises: Based on the first array and the second array, determining a third calibration parameter of the rotation axis center of the rotation axis to be measured in the first direction and a fourth calibration parameter of the rotation axis center in the second direction; adjusting the position of the center of the rotation axis based on the third calibration parameter and the fourth calibration parameter; Among them, the first direction is the direction of the line between the first point and the center of the first measuring device, the second direction is the direction of the line between the second point and the center of the second measuring device, the value of the third calibration parameter is half of the second target value, the second target value is the difference between the sixth measurement value and the eighth measurement value, and the value of the fourth calibration parameter is half of the third target value, and the third target value is the difference between the fifth measurement value and the seventh measurement value.

9. The method according to any one of claims 5 to 8, characterized in that The first connecting line and the second connecting line are perpendicular to each other, wherein the first connecting line is a connecting line between the first point and the center of the sphere, and the second connecting line is a connecting line between the second point and the center of the sphere.

10. The method according to claim 9, characterized in that A third line between the first point and the center of the first measuring device is perpendicular to the rotation plane of the rotation axis to be measured, and a fourth line between the second point and the center of the second measuring device is parallel to the rotation plane of the rotation axis to be measured.

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