A cradle type five-axis machine rotary shaft positioning precision detection and error compensation method

Abstract

The application discloses a cradle type five-axis machine rotating shaft positioning precision detection and error compensation method, generates coordinate information of rotating circles around the C shaft under different A values in a reference coordinate system, and fits the coordinate information of the rotating circles around the A shaft from the centers of the rotating circles around the C shaft under different A values; compares actual rotating angles of the A shaft and the C shaft with mechanical coordinate change angles respectively according to the coordinate information of the rotating circles around the C shaft and the coordinate information of the rotating circles around the A shaft, and detects positioning precision of the A shaft and the C shaft; respectively compensates errors of the positioning precision of the A shaft and the C shaft, respectively converts rotating angles of mechanical coordinate systems of the A shaft and the C shaft with spatial rotating angles of the reference coordinate system, and compensates errors, wherein it is assumed that rotation between adjacent angles which have been detected is uniform during compensation, and the application improves machining precision of the five-axis machine and has good practicability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of five-axis machine precision detection and compensation, and particularly relates to a cradle type five-axis machine rotating shaft positioning precision detection and error compensation method. BACKGROUND

[0002] Compared with the traditional three-axis machine, the five-axis machine has higher machining precision, higher machining efficiency and can process more complex workpieces, and has more competitive advantages in the market. At the same time, due to the increase of two rotating shafts, the mechanical structure of the five-axis machine becomes more complex, and combined with the geometric error of the machine mechanical structure itself and the wear error caused by the machine operation, these factors pose a great challenge to calibrate the geometric structure parameters of the five-axis machine and eliminate various errors.

[0003] The five-axis machine on the market is mainly divided into three types of double-rotating table structure, single-swing table-single-rotating table structure and double-swing head structure. According to different mechanical structures, corresponding geometric mathematical models are established, and the radial, axial and tangential axis deviations of the rotating shaft are measured by instruments such as level meter and ball bar, and the eccentricity of the rotating shaft is calculated to detect the rotating shaft. The existing technology mostly uses laser interferometer, micrometer and ball bar to measure the positioning precision of the five-axis machine and calibrate the processing. The operation is complicated, the description of the rotating shaft problem is not comprehensive, the calibration precision of some five-axis machines with problems is not enough, and there is no good description and detection method for the connection rigidity problem of the rotating shaft of some five-axis machines. Therefore, the present application provides a cradle type five-axis machine rotating shaft positioning precision detection and error compensation method. The mechanical coordinates of a point on the machine table at different poses can complete the A-axis and C-axis detection and five-axis machine calibration. The A-axis and C-axis problems are detected and error compensation calibration is performed at the same time, which improves the machining precision of the five-axis machine. SUMMARY

[0004] The present application aims to provide a cradle type five-axis machine rotating shaft positioning precision detection and error compensation method to solve the above problems.

[0005] The present application is mainly realized by the following technical solutions:

[0006] A cradle type five-axis machine rotating shaft positioning precision detection and error compensation method, including a mechanical coordinate system and a reference coordinate system that can be converted to each other, and a reference coordinate system is established with the position of the laser emission at the origin of the mechanical coordinate system as the origin, including the following steps:

[0007] Step S100: generating coordinate information of a C-axis rotating circle at different A values in the reference coordinate system, and fitting the coordinate information of the A-axis rotating circle from the center of the C-axis rotating circle at different A values;

[0008] Step S200: detecting the positioning accuracy of the A-axis and the C-axis by comparing the actual rotation angle of the A-axis and the C-axis with the mechanical coordinate change angle of the A-axis and the C-axis respectively based on the coordinate information of the circle rotating around the C-axis and the coordinate information of the circle rotating around the A-axis;

[0009] Step S300: performing error compensation on the positioning accuracy of the A-axis and the C-axis respectively, and converting the rotation angle of the mechanical coordinate system of the A-axis and the C-axis with the space rotation angle of the reference coordinate system respectively to perform error compensation, and assuming that the rotation between the adjacent angles that have been measured is uniform during the compensation.

[0010] To better realize the present application, further, in the step S100, the laser range finder is used to obtain the mechanical coordinates of the sphere center, and a series of mechanical coordinates of a same point on the machine table are obtained when the C-axis rotates at different angles of the A-axis, and the mechanical coordinates of the point include the mechanical coordinates of the XYZ-axis coordXYZ M [ X i ,Y i ,Z i ] T , the mechanical coordinates of the A-axis and the C-axis coordAC M [ A i , C i ] T , and the corresponding reference system coordinates are obtained by converting the mechanical coordinates to the reference coordinate system.

[0011] To better realize the present application, further, the step S200 includes the following steps:

[0012] Step S210: detecting the positioning accuracy of the C-axis:

[0013] When the A-axis is at a certain angle and does not change, the C-axis is rotated, and there is a reference system coordinate every certain angle disAngleCMachine, and a space circle is fitted by using all the coordinates in the rotation process, and then the actual rotation angle disAngleC between the points can be obtained, and the positioning accuracy of the C-axis is detected by comparing disAngleCMachine and disAngleC;

[0014] Step S220: detecting the positioning accuracy of the A-axis:

[0015] The center of all the rotation circles around the C axis can be fitted with a circle rotating around the A axis, which is Circle A, the center of which is cptA, and the unit normal vector is cnA. The actual rotation angle of the A axis after the change of the center of the circle is obtained, and the actual rotation angle of the A axis and the mechanical coordinate change angle of the A axis are compared to detect the positioning accuracy of the A axis.

[0016] To better realize the present application, further, the step S300 comprises the following steps:

[0017] Step S310: error compensation of the A axis;

[0018] For the A axis, the actual rotation angle between the adjacent angles of the known A value is measured, and the mechanical coordinate of the A axis is angle M When angle M The actual rotation angle between the two mechanical coordinates angle 1 M angle 2 M , angle 1 M to angle 2 M is dAngle , and the actual rotation angle from angle 1 M to angle M is required dAngle 0:

[0019] .

[0020] To better realize the present application, further, the step S300 further comprises the following steps:

[0021] Step S320: error compensation of the C axis;

[0022] Suppose that the angles between the C axis mechanical coordinates of each rotation circle around the C axis are measured, which are 0, 60, 120, …, 300, 360; the mechanical coordinate of the A axis is angle MA , and the mechanical coordinate of the C axis is angle MC When the A axis angle MA has the known A value, the two mechanical coordinates angle 1 MA , angle 2 MA have the measured data; and the C axis angle MCbetween two mechanical coordinates of the A-axis angle 1 MC , angle 2 MC , the A-axis is angle 1 MA , the C-axis rotates dAngleC1 from angle 1 MC , angle 2 MC , the A-axis is angle 2 MA , the C-axis rotates dAngleC2 from angle 1 MC , angle 2 MC , the actual rotation angle of the C-axis from 0 to angle MC is required angle .

[0023] The step S320 includes a step S321, a step S322 and a step S323.

[0024] Step S321: the actual rotation angle of the C-axis from 0 to angle 1 MA is obtained angle MC Angle 10.

[0025] Specifically, since all angles of the C-axis from 0 to angle 1 MA have been measured and can be added to be angle 1 MC , the actual rotation angle of the C-axis from angleAdd 1 MC to angle 1 MC is angle 1, then: dAngle

[0026]

[0027] Angle 10= dAngle 1 + angleAdd 1 .

[0028] Step S322: the actual rotation angle of the C-axis from 0 to angle 2 MA is obtained angle MC Angle 20 .

[0029] Similarly, the mechanical coordinate of the A-axis is angle 2 MA All the angles of the C-axis from 0 to angle 1 MC have been measured and can be added to be angleAdd 2; the actual rotation angle of the C-axis from angle 1 MC to angle MC is dAngle 2; then:

[0030] ;

[0031] Angle 20= dAngle 2+ angleAdd 2.

[0032] Step S323: find the actual rotation angle of the C-axis from 0 to angle MC angle :

[0033] .

[0034] To better realize the present application, further comprising step S400, to keep the relative position of a certain point on the tool or workpiece in space unchanged, the real-time coordinates of the certain point with the change of the A-axis and C-axis are needed, and let the mechanical coordinates (x, y, z, a, c) of a certain mechanical coordinate system be the mechanical coordinates (x1, y1, z1, a1, c1) of another mechanical coordinate system, and the calibration steps are as follows:

[0035] Step S410: first convert the mechanical coordinates (x, y, z) into the reference system coordinates (x 参 , y 参 , z 参 );

[0036] Step S420: first get the machine table coordinate system 1 under the A-axis a, calculate the actual rotation angle of the C-axis relative to 0 as θ1, rotate the machine table coordinate system 1 by θ1 around the C-axis at this time to get the machine table coordinate system 1', and then get the coordinates (x', y', z') of (x 参 , y 参 , z 参 ) in the machine table coordinate system 1';

[0037] Step S430: get the machine table coordinate system 2 under the A-axis a1, calculate the actual rotation angle of the C-axis relative to 0 as θ2, rotate the machine table coordinate system 2 by θ2 around the C-axis at this time to get the machine table coordinate system 2', and convert the coordinates (x', y', z') under the machine table coordinate system 2' to the reference coordinate system to get (x​参1 ,y 参1 ,z 参1 );

[0038] Step S440: convert the coordinates (x 参1 ,y 参1 ,z 参1 ) in the reference coordinate system into coordinates (x1, y1, z1) in the mechanical coordinate system, that is, (x1, y1, z1, a1, c1) is obtained.

[0039] The beneficial effects of the present application are as follows:

[0040] The present application needs to meet the mechanical coordinates and the reference system coordinates can be converted to each other, and the rotation track of a point on the machine table around the C-axis is a good circle, which is broad in premise and wide in application range. A series of mechanical coordinates of a point on the machine table in different postures are used to realize the problem detection of the A-axis and the C-axis of the mechanical structure, and the present application only needs to measure the coordinates of a point on the machine table in different postures of the A-axis and the C-axis to generate relevant information, which is more convenient.

[0041] The present application can still realize calibration for some five-axis machines with problems. The current measurement obtains the center of the ball on the machine table by using a laser range finder, and other measurement methods can also be used. With the improvement of the accuracy of the measuring instrument and the mechanical performance, the calibration accuracy will also be improved. All the above information only needs to be generated directly after the operator obtains a series of mechanical coordinates of a point on the machine table in different postures, which is simple to operate and greatly simplifies the calibration process. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is the overall flowchart of the present application.

[0043] Figure 2 is the flowchart of the mechanical calibration of the five-axis machine.

[0044] Figure 3 is the detection curve of the positioning accuracy of the A-axis of the old five-axis machine.

[0045] Figure 4 is the detection curve of the positioning accuracy of the C-axis of the old five-axis machine.

[0046] Figure 5 is the detection curve of the positioning accuracy of the A-axis of the new five-axis machine.

[0047] Figure 6 is the detection curve of the positioning accuracy of the C-axis of the new five-axis machine. DETAILED DESCRIPTION

[0048] Example 1:

[0049] A cradle type five-axis machine tool rotating shaft positioning accuracy detection and error compensation method, including mutually convertible mechanical coordinate system and reference coordinate system, the position of laser emission at the origin of the mechanical coordinate system as the origin to establish the reference coordinate system, as shown in Figure 1 The method comprises the following steps:

[0050] Step S100: generate coordinate information of the rotating circle around the C axis under different A values in the reference coordinate system, and fit the coordinate information of the rotating circle around the A axis from the center of the rotating circle around the C axis under different A values;

[0051] Step S200: compare the actual rotation angles of the A axis and the C axis with the mechanical coordinate change angles respectively based on the coordinate information of the rotating circle around the C axis and the coordinate information of the rotating circle around the A axis, and detect the positioning accuracy of the A axis and the C axis;

[0052] Step S300: error compensation is performed on the positioning accuracy of the A axis and the C axis respectively, and the rotation angles of the mechanical coordinate system of the A axis and the C axis are converted with the spatial rotation angles of the reference coordinate system for error compensation, and it is assumed that the rotation between the adjacent angles that have been measured is uniform during compensation;

[0053] Step S400: in order to keep the relative position of a specific point on a tool or a workpiece unchanged in space, the real-time coordinates of the specific point changing with the A axis and the C axis need to be obtained, and a mechanical coordinate system coordinate (x, y, z, a, c) is set to another mechanical coordinate system coordinate (x1, y1, z1, a1, c1).

[0054] Preferably, in the step S100, a laser range finder is used to obtain the mechanical coordinates of the sphere center, and a series of mechanical coordinates of a same point on the machine table are obtained by rotating the C axis at different angles of the A axis, and the mechanical coordinates of the point include the mechanical coordinates of the XYZ axis coordXYZ M [ X i ,Y i ,Z i ] T , the mechanical coordinates of the A axis and the C axis coordAC M [ A i ,C i ] T , and the corresponding reference system coordinates are obtained by converting the mechanical coordinates to the reference coordinate system.

[0055] Preferably, the step S200 comprises steps S210 and S220.

[0056] Step S210: detect the positioning accuracy of the C axis:

[0057] When the A-axis is at a certain angle, the C-axis is rotated, and a reference frame coordinate is obtained every disAngleCMachine angle. All the coordinates in the rotation process are fitted to a space circle, and the actual rotation angle disAngleC between points can be obtained. The disAngleCMachine and disAngleC are compared to detect the positioning accuracy of the C-axis;

[0058] Step S220: detecting the positioning accuracy of the A-axis:

[0059] All the centers of the circles rotated around the C-axis can be fitted to a circle rotated around the A-axis, which is set as CircleA, and the center of the circle is set as cptA and the unit normal vector is set as cnA. The actual rotation angle of the A-axis after the change of the center of the circle is obtained according to the known A value corresponding to the center of the circle rotated around the C-axis. The actual rotation angle of the A-axis is compared with the change angle of the mechanical coordinate of the A-axis to detect the positioning accuracy of the A-axis.

[0060] Preferably, the step S300 comprises a step S310 and a step S320.

[0061] Step S310: error compensation of the A-axis;

[0062] Specifically, for the A-axis, the actual rotation angle between the adjacent angles with known A values is measured, and the mechanical coordinate of the A-axis is set as angle M , angle M The actual rotation angle from the two mechanical coordinates angle 1 M angle 2 M , angle 1 M to angle 2 M is angle , and the actual rotation angle from angle 1 M to dAngle M is required to be angle 0 :

[0063] .

[0064] Step S320: error compensation of the C-axis;

[0065] Specifically, it is assumed that the angles between the mechanical coordinates of the circles rotated around the C-axis are measured, which are 0, 60, 120, …, 300, 360; and the mechanical coordinate of the A-axis is set as angle MA, C-axis mechanical coordinate is angle MC When A-axis mechanical coordinate is angle MA , C-axis mechanical coordinate is angle 1 MA , angle 2 MA ; A-axis mechanical coordinate is angle 1 MC , C-axis mechanical coordinate is angle 1 MC , angle 2 MC ; A-axis mechanical coordinate is angle 1 MA , C-axis mechanical coordinate is angle 1 MC , angle 2 MC ; A-axis mechanical coordinate is angle 2 MA , C-axis mechanical coordinate is angle 1 MC , angle 2 MC ; A-axis mechanical coordinate is angle MC , C-axis mechanical coordinate is angle .

[0066] The step S320 comprises a step S321, a step S322 and a step S323.

[0067] Step S321: obtaining the actual rotation angle of C-axis from 0 to Angle 1 MA when A-axis mechanical coordinate is angle 1 MC ; angle 10

[0068] Specifically, since all angles of C-axis from 0 to angleAdd 1 MA when A-axis mechanical coordinate is angle 1 MC have been measured and can be added to be angle 1 , the actual rotation angle of C-axis from dAngle 1 MC to Angle MC is dAngle 1 ; then:

[0069] ;

[0070] angleAdd 10= angle 1+angle 1.

[0071] Step S322: the A-axis mechanical coordinate is obtained as Angle 2 MA When the C-axis rotates from 0 to angle MC , the actual rotation angle is angle 20;

[0072] Similarly, the A-axis mechanical coordinate is obtained as angleAdd 2 MA When the C-axis rotates from 0 to angle 1 MC , all the angles are measured and added to be angle 2; the actual rotation angle of the C-axis from dAngle 1 MC to Angle MC is dAngle 2; then:

[0073] ;

[0074] angleAdd 20= angle 2+ angle 2.

[0075] Step S323: the actual rotation angle of the C-axis from 0 to Figure 2 MC is obtained as Figure 1 :

[0076] .

[0077] Preferably, as shown in coordXYZ , the step S400 comprises the following steps:

[0078] Step S410: first convert the mechanical coordinates (x, y, z) into the reference system coordinates (x 参 , y 参 , z 参 );

[0079] Step S420: first obtain the machine coordinate system 1 under the a-axis as a pose, calculate the actual rotation angle of the C-axis relative to 0 as θ1, rotate the machine coordinate system 1 around the C-axis at this time by θ1 to obtain the machine coordinate system 1', and then obtain the coordinates (x', y', z') of (x 参 , y 参 , z 参 ) in the machine coordinate system 1';

[0080] Step S430: get the machine coordinate system 2 in the a1 posture, calculate the actual rotation angle of the C-axis as c1 relative to 0 as θ2, rotate the machine coordinate system 2 around the C-axis at this time by θ2 to get the machine coordinate system 2', and convert the coordinates (x', y', z') in the machine coordinate system 2' to the reference coordinate system to get (x 参1 ,y 参1 ,z 参1 );

[0081] Step S440: convert the coordinates (x 参1 ,y 参1 ,z 参1 ) in the reference coordinate system to the coordinates (x1, y1, z1) in the mechanical coordinate system, that is, (x1, y1, z1, a1, c1) is obtained.

[0082] The present application realizes the problem detection of the A-axis and the C-axis of the mechanical structure by a series of mechanical coordinates of a point on the machine in different postures, and the present application only needs to measure the coordinates of a point on the machine in different postures of the A-axis and the C-axis to generate relevant information, which is more convenient and greatly simplifies the calibration process.

[0083] Embodiment 2

[0084] A cradle type five-axis machine rotation axis positioning precision detection and error compensation method, the premise is that the mechanical XYZ axis and the reference coordinate system (Cartesian coordinate system) can be converted to each other, and the current measurement adopts a laser range finder to obtain the spherical center mechanical coordinate, and other measurement methods can also be adopted. The rotation track of a point on the machine around the C-axis is a good circle, the principle is to obtain the circle information of each circle of the same point rotating around the C-axis under different A values in the reference coordinate system, detect the rotation of the A-axis and the C-axis of the five-axis machine, finally perform error compensation on the positioning precision of the A-axis and the C-axis, complete five-axis machine calibration, and realize the basis of five-axis linkage machining.

[0085] The present application detects the rotation positioning precision of the A-axis and the C-axis of the five-axis equipment by using the geometric figure information of the point on the machine rotating around the C-axis in the reference coordinate system, and can be used for the detection of the A-axis and the C-axis of the five-axis machine in various scenes, including five-axis machine factory detection, use problem detection, repair detection, etc. Error compensation is performed on the positioning precision of the A-axis and the C-axis to realize the calibration technology, which can improve the machining precision of the five-axis machine, and the equipment with problems in the A-axis and the C-axis can still be improved for use, and can be widely applied to various five-axis equipment.

[0086] I. Calibration purpose

[0087] The position of laser emission is taken as the origin of the reference coordinate system when the mechanical coordinate is (0, 0, 0), the connection between the mechanical coordinate system and the reference coordinate system and the connection between the reference coordinate system and the workpiece coordinate system are established, and the basis for realizing five-axis linkage machining is established. According to the information obtained above, tracking conversion from one mechanical coordinate (x, y, z, a, c) to another coordinate (x1, y1, z1, a1, c1) (a→a1, c→c1, x1, y1, z1 are calculated so that the relative position of a specific point on the tool or workpiece in space remains unchanged) can be realized.

[0088] II. Mechanical structure of five-axis point glue machine

[0089] The cradle type five-axis machine mainly comprises a machine tool base, three translation axes (X axis, Y axis and Z axis) and two rotation axes (A axis and C axis). Through the linkage between the machine tool base and the axes and the connection between the axes, a machining motion chain is formed, and five-axis linkage is realized. During the motion process, the machine tool base, the motion axes, the needle valve, the workpiece and the camera of the five-axis point glue machine are all regarded as rigid bodies based on the kinematics of robots, so that the above rigid body mechanical structure is divided into two machining motion chains.

[0090] 1. Machine tool base→X axis→Z axis→needle head;

[0091] 2. Machine tool base→Y axis→A axis→C axis→workpiece coordinate system;

[0092] As shown in coordAC the present application mainly comprises the following steps:

[0093] ① Generate the rotation circle information around the C axis under different A values in the reference coordinate system, and fit the rotation circle information around the A axis from the centers of the rotation circles around the C axis under different A values;

[0094] ② Obtain the positioning accuracy of the A axis and the C axis from the rotation circle information around the C axis and the rotation circle information around the A axis;

[0095] ③ Compensate the positioning accuracy of the A axis and the C axis, and establish the connection between the machine coordinate system and the reference coordinate system;

[0096] ④ Realize mechanical calibration of the five-axis machine.

[0097] III. Detailed steps and related principles

[0098] The detailed steps are as follows.

[0099] 1. Measurement data:

[0100] The current measurement adopts a laser range finder to obtain the mechanical coordinates of the sphere center, obtains a series of mechanical coordinates of the same point on the machine at different angles of the A axis and respectively rotates the C axis, and sets the mechanical coordinates of the point to include the mechanical coordinates of the XYZ axes angleM [ X i ,Y i ,Z i ] T Mechanical coordinates of A-axis, C-axis angle M [ A i ,C i ] T Note: On the premise of establishing the relationship between the mechanical XYZ-axis coordinate system and the reference coordinate system, all measured points are converted to the reference coordinate system, and the subsequent discussion data are all reference coordinate system data.

[0101] 2. Fit to get A-axis, C-axis geometric information:

[0102] The rotation circle of A-axis rotating around C-axis in different postures can be obtained in the reference coordinate system. The information of A-axis and C-axis can be obtained from the circle information. The existing five-axis machine has been tested, and the following problems are found:

[0103] (1) A-axis positioning accuracy is not enough;

[0104] (2) C-axis positioning accuracy is not enough;

[0105] (3) A-axis and C-axis are not well connected in rigidity.

[0106] In order to facilitate the discussion of the following content, make the following specific examples:

[0107] Suppose that when A-axis is-40, -30, -20, -10, 0, 10, 20, 30, 40 degrees, the corresponding circles rotating around C-axis are set as Circle1, Circle2, Circle3, Circle4, Circle5, Circle6, Circle7, Circle8, Circle9. For each circle, there is a corresponding center cpt1, cpt2, cpt3...cpt9, and a corresponding unit normal vector cn1, cn2, cn3,...cn9.

[0108] 3. Detect the positioning accuracy of C-axis:

[0109] When the A-axis is at a certain angle, rotate the C-axis, every certain angle (set as disAngleCMachine) has a reference frame coordinate, fit a space circle with all the coordinates in the rotation process, and then the actual rotation angle between points (set as disAngleC) can be obtained. Compare disAngleCMachine and disAngleC to detect the positioning accuracy of the C-axis.

[0110] 4. Detect the positioning accuracy of the A-axis:

[0111] From the centers of all the circles rotating around the C-axis, cpt1, cpt2, cpt3...cpt9, a circle rotating around the A-axis can be fitted, which is set as CircleA, and the center of the circle is set as cptA and the unit normal vector is set as cnA. As mentioned earlier, the A values corresponding to cpt1, cpt2, cpt3...cpt9 are -40, -30, -20,...., 40. The actual rotation angle of the A-axis from cpt1 to cpt2, cpt2 to cpt3...cpt8 to cpt9 can be obtained. Compare the actual rotation angle of the A-axis with the mechanical coordinate change angle of the A-axis to detect the positioning accuracy of the A-axis.

[0112] 5. Error compensation for the positioning accuracy of the A-axis and the C-axis, convert the mechanical coordinate change angle of the A-axis and the C-axis into the actual rotation angle:

[0113] The mutual conversion of the rotation angle of the A-axis and the C-axis and the space rotation angle of the reference coordinate system can be error compensated. When compensating, it is assumed that the rotation between the adjacent angles has been measured uniformly. Since the actual rotation angle of the C-axis may be affected by the A-axis, the error compensation method of the C-axis is different from that of the A-axis.

[0114] A-axis compensation calculation method:

[0115] For the A-axis, from the previous content, the actual rotation angle between the adjacent angles of the A mechanical -40, -30, -20,..., 30, 40 is measured, and the A mechanical coordinate is set as angle M When angle M In the two mechanical coordinates with measurement data angle 1 M 、 angle 2 M , angle 1 M to angle 2 M , the actual rotation angle is dAngle, and the requirement is dAngle 1 M to angleM actual rotation angle of C-axis angle 0:

[0116] .

[0117] Compensation calculation method of C-axis:

[0118] For C-axis, the actual rotation angle of C-axis can be affected by A-axis. Suppose the angle of each rotation around C-axis is measured between 0, 60, 120, …, 300, 360. Set the A-axis mechanical coordinate as angle MA , and the C-axis mechanical coordinate as angle MC , it is known that the A-axis angle MA between the two mechanical coordinates with measurement data angle 1 MA , angle 2 MA . The C-axis angle MC between the two mechanical coordinates with measurement data angle 1 MC , angle 2 MC , the A-axis is angle 1 MA , the C-axis rotates dAngleC1 from angle 1 MC , angle 2 MC . When the A-axis is angle 2 MA , the C-axis rotates dAngleC2 from angle 1 MC , angle 2 MC . The actual rotation angle of C-axis from 0 to angle MC is required to be obtained.

[0119] Specifically, the angle is obtained by the following steps.

[0120] (1) The actual rotation angle of C-axis from 0 to Angle 1 MA is obtained. angle MC angle 10.

[0121] Since the A-axis mechanical coordinate is angleAdd 1 MA , the C-axis rotates from 0 to angle 1 MC ​All angles between 0 and 1 are measured and can be added up to be set as angle 1 dAngle 1 MC The actual rotation angle of C-axis from 0 to 1 is Angle MC dAngle 1

[0122] ;

[0123] angleAdd 10 angle 1 angle 1

[0124] (2) When the mechanical coordinate of A-axis is 2, the actual rotation angle of C-axis from 0 to 1 is 20. Angle 2 MA angle MC angle 20

[0125] Similarly, when the mechanical coordinate of A-axis is 2, the actual rotation angle of C-axis from 0 to 1 is 20. angleAdd 2 MA angle 1 MC angle 2 dAngle 1 MC Angle MC dAngle 2

[0126] ;

[0127] angleAdd 20 angle 2 angle 2

[0128] (3) The actual rotation angle of C-axis from 0 to 1 is Figure 2 MC Figure 3 :

[0129] .

[0130] 6. Realize mechanical calibration:

[0131] ​​​​​​​​The above mechanical coordinate system and reference coordinate system can be converted to each other, realizing the conversion of the A-axis and C-axis mechanical coordinate rotation angle to the actual rotation angle of the reference coordinate system, and obtaining the real-time coordinate system of the machine coordinate system after the A-axis and C-axis change. In order to keep the relative position of a certain point on the tool or workpiece unchanged in space, the real-time coordinates of the specific point with the change of the A-axis and C-axis are needed.

[0132] (1) Set a certain mechanical coordinate from one mechanical coordinate (x, y, z, a, c) to another coordinate (x1, y1, z1, a1, c1), (a→a1, c→c1, then calculate x1, y1, z1), as shown in Figure 5 , the specific process is as follows:

[0133] (1) First, convert the mechanical coordinate (x, y, z) to the reference coordinate system (x 参 ,y 参 ,z 参 ).

[0134] (2) First, get the machine coordinate system 1 under the A-axis a, calculate the actual rotation angle of the C-axis relative to 0 as θ1, rotate the coordinate system 1 around the C-axis (coordinate system 1 Z-axis) at this time θ1 to get the coordinate system 1', and then get the coordinates (x 参 ,y 参 ,z 参 ) in the coordinate system 1' (x', y', z').

[0135] (3) Get the machine coordinate system 2 under the a1 attitude, calculate the actual rotation angle of the C-axis relative to 0 as θ2, rotate the coordinate system 2 around the C-axis (coordinate system 3 Z-axis) at this time θ2 to get the coordinate system 2', and convert the coordinates (x', y', z') under the machine coordinate system 2' to the reference coordinate system to get (x 参1 ,y 参1 ,z 参1 ).

[0136] (4) Convert the coordinates (x 参1 ,y 参1 ,z 参1 ) in the reference coordinate system to the mechanical coordinates (x1, y1, z1), that is, (x1, y1, z1, a1, c1) is obtained.

[0137] Four, result inspection

[0138] The detection curve of the positioning accuracy of the A-axis shows the positioning accuracy of the A-axis. The horizontal coordinate represents the mechanical coordinate of the A-axis, and the vertical coordinate represents the difference between the change of the mechanical coordinate of the A-axis from the previous angle to the current angle and the actual rotation angle. The detection curve of the positioning accuracy of the C-axis shows the positioning accuracy of the C-axis, the horizontal coordinate represents the mechanical coordinate of the C-axis, and the vertical coordinate represents the difference between the change of the mechanical coordinate of the C-axis from the previous angle to the current angle and the actual rotation angle. Different broken lines represent information of the rotation circle of the C-axis at different angles of the A-axis.

[0139] It is known that the positioning accuracy of the A-axis and the C-axis of the old five-axis machine is poorer than that of the new five-axis machine. By comparing Figure 3 and Figure 4 , it is found that the positioning accuracy of the A-axis of the old five-axis machine in Figure 6 is poor; by comparing Figure 4 and ​ , it is found that the positioning accuracy of the C-axis of the old five-axis machine in ​ is poor, which verifies that the detection result of the present application is better in accuracy.

[0140] After the mechanical calibration is realized in the above manner, the relative position of a certain specific point on the tool or the workpiece in space remains unchanged from one mechanical coordinate (x, y, z, a, c) to another coordinate (x1, y1, z1, a1, c1), and for machines with better A-axis and C-axis, very high accuracy can be achieved, and for machines with poor A-axis and C-axis, the calibration accuracy can also be greatly improved.

[0141] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification or equivalent change made according to the technical essence of the present application to the above embodiment falls within the protection scope of the present application.

Claims

1. A method for detecting the positioning accuracy and compensating for errors of the rotating axis of a cradle-type five-axis machine, comprising a convertible mechanical coordinate system and a reference coordinate system, wherein the reference coordinate system is established with the laser emission position at the origin of the mechanical coordinate system as the origin, characterized in that, Includes the following steps: Step S100: Generate coordinate information of the circle rotating around the C-axis under different A values ​​in the reference coordinate system, and obtain the coordinate information of the circle rotating around the A-axis by fitting the center of the circle rotating around the C-axis under different A values; In step S100, a laser rangefinder is used to obtain the mechanical coordinates of the sphere's center, and the mechanical coordinates of the same point on the machine tool are obtained at different angles along the A-axis, with the C-axis rotated. These mechanical coordinates are assumed to include the mechanical coordinates of the XYZ axes. coordXYZ M =[ X i ,Y i ,Z i ] T Mechanical coordinates of A-axis and C-axis coordAC M =[ A i ,C i ] T The mechanical coordinates are transformed into the reference coordinate system to obtain the corresponding reference coordinates. Step S200: Using the coordinate information of the circle rotating around the C-axis and the coordinate information of the circle rotating around the A-axis, compare the actual rotation angles and mechanical coordinate change angles of the A-axis and C-axis respectively to detect the positioning accuracy of the A-axis and C-axis; Specifically, step S200 includes steps S210 and S220; Step S210: Check the positioning accuracy of the C-axis: When the A-axis is at a certain fixed angle, rotate the C-axis. At certain angles, disAngleCMachine has a reference coordinate system. Fit a spatial circle with all the coordinates during the rotation process, and then obtain the actual rotation angle disAngleC between the points. Compare disAngleCMachine and disAngleC to detect the positioning accuracy of the C-axis. Step S220: Check the positioning accuracy of axis A: From the centers of all the circles rotating around the C-axis, a circle rotating around the A-axis can be fitted, denoted as CircleA, with its center denoted as cptA and its unit normal vector denoted as cnA. Since the A-values ​​corresponding to the centers of all the circles rotating around the C-axis are known, the actual rotation angle of the A-axis after the center change can be obtained. By comparing the actual rotation angle of the A-axis with the change angle of the A-axis mechanical coordinates, the positioning accuracy of the A-axis can be detected. Step S300: Perform error compensation for the positioning accuracy of the A-axis and C-axis respectively. Convert the rotation angle of the mechanical coordinate system of the A-axis and C-axis to the spatial rotation angle of the reference coordinate system respectively, and perform error compensation. During the compensation, it is assumed that the rotation between adjacent angles that have been measured is uniform. Step S300 includes steps S310 and S320; Step S310: Error compensation for the A-axis: For axis A, the actual rotation angle between adjacent angles with known A values ​​is measured. Let the mechanical coordinate of axis A be... angle M hour, angle M Two machine coordinates with measurement data angle 1 M , angle 2 M Between, from angle 1 M arrive angle 2 M The actual rotation angle is dAngle The requirement is to start from angle 1 M arrive angle M actual rotation angle dAngle 0: ； Step S320: C-axis error compensation: Assume that the mechanical coordinates of the C-axis of each rotation circle about the C-axis are measured to be between 0, 60, 120, ..., 300, 360; let the mechanical coordinates of the A-axis be... angle MA The C-axis mechanical coordinate is angle MC When, axis A is known angle MA Two machine coordinates with measurement data angle 1 MA , angle 2 MA Between, C-axis angle MC Two machine coordinates with measurement data angle 1 MC , angle 2 MC between; A-axis is angle 1 MA At that time, the C-axis from angle 1 MC arrive angle 2 MC It rotated dAngleC 1; A-axis is angle 2 MA At that time, the C-axis from angle 1 MC arrive angle 2 MC It rotated dAngleC 2; To obtain the C-axis from 0 to angle MC actual rotation angle angle ; Step S320 specifically includes steps S321, S322, and S323; Step S321: Obtain the mechanical coordinates of axis A. angle 1 MA When the C-axis is from 0 to angle MC actual rotation angle Angle 10; Specifically, since the mechanical coordinate of axis A is angle 1 MA When the C-axis is from 0 to angle 1 MC All the angles between them have been measured and can be summed up to set as... angleAdd 1. C-axis from angle 1 MC arrive angle MC The actual rotation angle is dAngle 1; then: ； Angle 10= dAngle 1+ angleAdd 1； Step S322: Obtain the mechanical coordinates of axis A. angle 2 MA When the C-axis is from 0 to angle MC actual rotation angle Angle 20; Similarly, the A-axis mechanical coordinate is angle 2 MA When the C-axis is from 0 to angle 1 MC All the angles between them have been measured and can be summed up to set as... angleAdd 2. C-axis from angle 1 MC arrive angle MC The actual rotation angle is dAngle 2; then: ； Angle 20= dAngle 2+ angleAdd 2； Step S323: Calculate the C-axis from 0 to... angle MC actual rotation angle angle : 。 2. The method for detecting and compensating for the positioning accuracy of the rotating shaft of a cradle-type five-axis machine according to claim 1, characterized in that, The process also includes step S400, which requires obtaining the real-time coordinates of a specific point on the tool or workpiece that varies with the A-axis and C-axis to ensure that the relative position of that specific point in space remains constant. Let's assume the coordinates (x, y, z, a, c) in one machine coordinate system are converted to (x1, y, z1, a1, c1) in another machine coordinate system. The calibration steps are as follows: Step S410: First, convert the machine coordinates (x, y, z) to reference coordinates (x, y, z). 参 ,y 参 ,z 参 ); Step S420: First, obtain the machine coordinate system 1 with A-axis in attitude a. Calculate the actual rotation angle of C-axis relative to 0, setting it as θ1. Rotate machine coordinate system 1 around the C-axis at this time by θ1 to obtain machine coordinate system 1'. Then obtain (x... 参 ,y 参 ,z 参 The coordinates (x', y', z') of the machine coordinate system 1'. Step S430: Obtain the machine coordinate system 2 under attitude a1, calculate the actual rotation angle of the C-axis relative to 0 and set it as θ2, rotate the machine coordinate system 2 around the C-axis at this time by θ2 to obtain the machine coordinate system 2', and transfer the coordinates (x', y', z') under the machine coordinate system 2' to the reference coordinate system to obtain (x 参1 ,y 参1 ,z 参1 ); step S440: The coordinates (x) in the reference coordinate system... 参1 ,y 参1 ,z 参1 Converting the coordinates to the machine coordinate system (x1, y1, z1) yields (x1, y, z1, a1, c1).

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