CN113290330B - A method for calibrating the spatial position of a laser processing head for a six-axis five-linkage machine tool - Google Patents

Abstract

The invention provides a method for calibrating the spatial position of a laser processing head of a six-axis five-linkage machine tool, which solves the problems that the laser focus of the six-axis five-linkage machine tool and the C-axis rotation center coordinate are difficult to find and influence the subsequent processing precision. The method comprises the steps of arranging a detection flat plate on a C-axis rotary table, engraving a motion track of each axis on a high-precision detection flat plate by a laser focus, and capturing coordinates of each intersection point through a visual interface to obtain XYZ machine tool coordinates of the C-axis rotary table so as to establish a coordinate relation between the laser focus and the C-axis.

Description

A method for calibrating the spatial position of a laser processing head for a six-axis five-linkage machine tool

technical field

The invention belongs to the field of laser processing, in particular to a method for calibrating the spatial position of a laser processing head of a six-axis five-linkage machine tool.

Background technique

Laser processing technology has become a key processing technology for large components in aviation, aerospace and other fields due to its advantages of non-contact, approximate "cold processing", no pollution and wide material applicability. During laser processing, it is necessary to accurately calibrate the relative positional relationship between the laser focus and each axis to lay the foundation for subsequent parts processing.

In practical engineering applications, for some machine tool structures, the laser machine tool cannot drive the optical components to move the laser focus to the center of the turntable, so that the position of the laser focus does not meet the processing requirements. For example, the six-axis five-linkage laser machine tool adopts a vertical milling structure. The C axis is installed on the saddle of the X axis, and the X axis drives the C axis to perform linear motion; the Y axis and the X axis are independent, the Z axis is mounted on the Y axis saddle, and the Y axis drives the Z axis to perform linear motion; the optical transmission system passes The marble mounting plate is connected with the Z-axis saddle, and the Z-axis drives the optical transmission system to move up and down; the X/Y/Z/A/B axes of the machine tool are interpolated to achieve five-axis linkage, but the C-axis as an indexing axis is not connected with other axes. For linkage, there is a deviation between the center of the C-axis turntable and the position of the laser focus, which is difficult to find, which will affect the subsequent processing accuracy.

SUMMARY OF THE INVENTION

The invention provides a method for calibrating the spatial position of a laser processing head of a six-axis five-linkage machine tool, which solves the problem that the laser focus of the six-axis five-linkage machine tool and the C-axis rotation center coordinate are difficult to be aligned, which affects the subsequent processing accuracy.

To achieve the above object, the present invention adopts the following technical solutions:

A method for calibrating the spatial position of a laser processing head of a six-axis five-linkage machine tool, comprising the following steps:

Step 1. Set a laser focus position calibration device on the laser processing head of the six-axis five-linkage machine tool, and the laser focus position calibration device includes a ranging sensor and a vision camera;

Step 2. Set a detection plate on the C-axis turntable table of the six-axis five-linkage machine tool;

Step 3: Move the ranging sensor to adjust the spatial attitude of the detection plate so that its surface is parallel to the plane of the XY axis;

Step 4: Adjust the position of the laser processing head, make the laser beam perpendicular to the detection plate, and make the laser focus fall on the surface of the detection plate;

Step 5: Adjust the position of the imaging surface of the vision camera, so that the vision camera has a clear image at the laser focus;

Step 6: Rotate the C-axis turntable, and the laser beam emitted by the laser processing head forms a circular trajectory on the detection plate;

Step 7. Move the X-axis and Y-axis of the six-axis five-linkage machine tool, so that the laser beam forms two parallel lines on the detection plate, and the two parallel lines intersect with the circular trajectory to obtain four intersection points J1, J2, J3, J4;

Step 8. Move the X-axis and Y-axis of the six-axis five-linkage machine tool to find four intersection points through the visual camera, so that the laser focus in the visual interface coincides with the intersection points J1, J2, J3, and J4 respectively, and read the laser in the visual interface. Coordinates (x ₁ , y ₁ ), (x ₂ , y ₁ ), (x ₃ , y ₂ ), (x ₄ , y ₂ )) when the focus coincides with the intersection points J1, J2, J3, and J4;

Step 9. Obtain the X and Y coordinates of the C-axis rotation center through the coordinates of the four laser focal points;

Step 10. Adjust the position of the laser processing head so that the axis of the laser beam is parallel to the table surface of the C-axis turntable, move the Z-axis so that the laser focus in the visual interface coincides with the end face of the C-axis turntable, and obtain the z-axis coordinate of the C-axis rotation center, Then, the XYZ machine coordinates (x, y, z) of the C-axis turntable are obtained, thereby establishing the coordinate relationship between the laser focus and the C-axis.

Further, in step ten, adjust the A-axis and B-axis to 0°, so that the axis of the focusing mirror of the laser processing head is parallel to the C-axis table, and move the Z-axis up and down to make the laser focus in the visual interface coincide with the C-axis end face, by This obtains the Z-axis coordinate value z of the C-axis end face.

Further, in step 1, the vision camera is a coaxial vision camera or a paraxial vision camera.

Further, in step 2, the flatness of the detection plate is within 0.02mm.

Further, in step 1, the ranging sensor is a rangefinder sensor.

Compared with the prior art, the method of the present invention has the following beneficial effects:

1. The method of the present invention sets a detection plate on the C-axis turntable, and the laser focus draws the motion trajectory of each axis on the high-precision detection plate, and then captures the coordinates of each intersection point through the visual interface, thereby obtaining the XYZ machine coordinates of the C-axis turntable, Thus, the coordinate relationship between the laser focus and the C-axis is established. The coordinates of each point measured by this method are the actual laser focus position, and the accuracy is high.

2. In the method of the present invention, the ranging sensor and the visual camera are detachable structures, which do not affect the optical path of laser processing. The ranging sensor can achieve high-precision alignment of the laser focus, and the laser focus can be calibrated by coaxial or paraxial vision. The position in the interface enables high-precision alignment of the laser focus.

3. The method of the present invention obtains the X and Y coordinates of the C-axis rotation center by calculating the laser marking on the detection plate. The method is direct and simple, the required device structure is simple and the cost is low, and it is very suitable for six-axis five-linkage. The calibration of the coordinates of the machine tool coordinate system of the C-axis table in the machine tool.

Description of drawings

1 is a schematic structural diagram of a six-axis five-linkage laser machine tool of the present invention;

Fig. 2 is the installation schematic diagram of the visual camera and the ranging sensor of the present invention;

FIG. 3 is a schematic diagram of the trajectory of the laser focus in the method of the present invention.

Reference numerals: 1-Z-axis, 2-Optical transmission system, 3-Z-axis saddle, 4-Y-axis saddle, 5-Y-axis, 6-X-axis, 7-X-axis saddle, 8-C-axis , 9-workpiece, 10-beam space pointing and positioning module, 21-vision camera, 22-laser focusing module, 23-ranging sensor, 24-laser focus.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

As shown in Figure 1, the six-axis five-linkage laser machine tool is mainly composed of optical transmission system 2, X-axis 6, Y-axis 5, Z-axis 1, A-axis, B-axis and C-axis 8. Optical transmission system 2 is installed on the Z-axis On the saddle 3, the Z axis 1 is installed on the Y axis saddle 4, and the movement of the Z axis 1 and the Y axis 5 can realize the movement of the optical transmission system in the Y and Z directions; the beam space in the optical transmission system 2 points to the positioning module 10 is set on the A axis and B axis, the A axis and B axis can realize the rotation of the laser beam around the X axis 6 and the Z axis 1 direction, the C axis 8 is installed on the X axis saddle 7, and the workpiece 9 can be realized by the C axis 8 Indexing processing. After the six-axis five-linkage machine tool is integrated, the machine tool coordinate system coordinates of the C-axis 8 rotation center are the key data to realize the processing of workpiece 9. The relationship between its spatial coordinates and the spatial position coordinates of the laser focus 24 is established to provide data for the establishment of the workpiece 9 coordinate system. . Based on this, the present invention provides a method for calibrating the spatial position of the laser processing head of a six-axis five-linkage machine tool, which indirectly measures the loudness displacement relationship between the laser focus 24 and the C-axis 8 turntable, and realizes the spatial positioning and focusing of the laser beam. The method is accurate High degree of precision, laying a reliable foundation for subsequent laser processing.

The method for calibrating the spatial position of the laser processing head of the six-axis five-linkage machine tool provided by the present invention is specifically a method for calibrating the mutual positional relationship between the center of rotation of the C-axis 8 and the laser focus 24 .

First, build a laser focus position calibration device on the laser processing laser focusing module 22, which is mainly composed of a coaxial or paraxial vision camera 21 and a paraxial ranging sensor 23. The vision camera 21 and the ranging sensor 23 are detachable. Does not affect the optical system;

Next, place a detection plate with good flatness on the table surface of the C-axis 8 turntable, and adjust the spatial attitude of the detection plate through the ranging sensor 23 so that its surface is parallel to the XY axis 5 motion plane with high precision. Adjust the attitude of the beam space pointing positioning module 10 so that the laser beam is perpendicular to the detection plate, calibrate the position of the laser focus 24 by the ranging sensor 23, and adjust the position of the laser focus 24 in the Z direction based on the value of the ranging sensor 23, so that The laser focus 24 is exactly in the plane of the plate. After the laser focus 24 is aligned, adjust the position of the vision camera 21 so that the vision is the clearest at the focus, and the vision camera 21 is used to zoom in and realize the position of the laser focus 24 for real-time observation; then, adjust the laser parameters so that the laser focus 24 is at The width of the engraved line on the detection plate should be kept within 0.1mm;

Again, rotate the C-axis 8 turntable to make the laser focus 24 engrave a circular trajectory on the detection plate, then move the X-axis 6 and Y-axis 5, and use the laser focus 24 to engrave two secant lines on the detection plate, thus obtaining The focus of the intersection of the two secant lines and the circular trajectory, move the X/Y axis 5 of the machine tool, and find four intersection points through the visual camera 21, so that the laser focus 24 in the visual interface coincides with the positions of the four intersection points. The machine tool coordinates of each axis of the machine tool at the intersection point. By measuring the intersection point coordinates of the secant line and the ring, the coordinates of the C-axis 8 rotation center in the XY coordinate system can be obtained;

Finally, adjust the attitude of the beam space pointing positioning module 10 so that the laser beam is parallel to the C-axis 8 table, and find the machine tool Z-axis 1 coordinate where the C-axis 8 table and the laser focus 24 coordinates are coincident through the visual camera 21 interface, so as to obtain the C-axis 8 The XYZ machine tool coordinates of the worktable establish the coordinate relationship between the laser focus 24 and the C axis 8 .

The device required by the method of the invention has a simple and cheap structure, and is very suitable for the calibration of the coordinates of the coordinate system of the C-axis and 8-table machine tool in the six-axis five-linkage machine tool.

Based on the above description, the method for calibrating the spatial position of the laser processing head of the six-axis five-linkage machine tool provided by the present invention specifically includes the following steps:

Step 1. Set a laser focus position calibration device on the laser focusing module 22 of the laser processing head of the six-axis five-linkage machine tool. The laser focus position calibration device includes a ranging sensor 23 and a visual camera 21, that is, the beam space points to the positioning module 10 head. A vision camera 21 and a ranging sensor 23 are installed in the part;

The vision camera 21 is a coaxial vision camera 21 or a rangefinder vision camera 21, and the ranging sensor 23 is a rangefinder sensor 23. The vision camera 21 and the rangefinder sensor 23 are detachable and do not affect the optical system. The rangefinder sensor 23 can be used for The laser focus 24 is repeatedly identified with high precision, and the visual camera 21 can mark the position of the laser focus 24 in the visual interface with high precision, which is convenient to use the visual interface to find the machine coordinates of the laser etching track;

Step 2. Set a detection plate on the table surface of the C-axis 8 turntable of the six-axis five-linkage machine tool, and its flatness is within 0.02mm;

Step 3: Move the distance measuring sensor 23 to detect whether the flat plate is parallel to the plane of movement of the XY axis 5, and adjust the posture of the detection plate so that its surface is parallel to the plane of the XY axis 5;

Step 4: Adjust the position of the laser processing head, make the laser beam perpendicular to the detection plate, make the laser focus 24 fall on the surface of the detection plate, calibrate the position of the laser focus 24 by the ranging sensor 23, and obtain the calibration value of the ranging sensor 23;

In this step, adjust the beam space to point to the A-axis and the B-axis in the positioning module 10, so that the axis of the focusing mirror is perpendicular to the end face of the C-axis 8, that is, when the B-axis is at the zero position, the axis of rotation of the A-axis motor is parallel to the X-axis 6; When the A-axis motor is at the zero position, the center line of the focusing mirror is parallel to the Y-axis 5; adjust the beam space to point the A-axis and B-axis in the positioning module 10 to 90° and -90°, respectively, so that the focusing mirror axis is perpendicular to the C-axis 8 end faces;

Step 5: Adjust the position of the imaging plane of the vision camera 21 so that the vision camera 21 has the clearest imaging at the focus, and at the same time calibrate the position of the laser focus 24 on the vision interface, and the measurement value of the ranging sensor 23 is now zero;

Step 6. Rotate the C-axis 8 turntable, and the laser beam emitted by the laser processing head forms a circular trajectory on the detection plate; at this time, the laser focus 24 is far away from the C-axis 8 rotation center, and the distance between the laser focus 24 and the C-axis 8 rotation center is: R, rotate the C axis 8 to form a circular track with a radius R on the plate;

Step 7. Move the X axis 6 and the Y axis 5 of the six-axis five-linkage machine tool, so that the laser beam forms two parallel lines on the detection plate, and the two parallel lines intersect with the circular trajectory to obtain four intersection points J1, J2, J3, J4;

Step 8. Move the vision camera 21 by moving the X axis 6 and the Y axis 5 of the six-axis five-linkage machine tool, and the vision camera 21 searches for four intersection points, so that the laser focus 24 in the visual interface coincides with the intersection points J1, J2, J3, and J4 respectively. , read the coordinates (X1, Y1), (X2, Y1), (X3, Y2), (X4, Y2)) when the focus of the visual interface coincides with points J1, J2, J3, and J4;

Step 9. The X and Y coordinates of the center of rotation of the C-axis 8 can be calculated by reading the four focus coordinates;

9.1) The distance between two parallel lines obtained by reading the Y-axis 5 coordinates is △Y, and the distance between the center of the turntable and the closer secant is E; the following calculation method is used to obtain the E value;

9.2) After calculating the E value, the X and Y coordinate values of the laser focus 24 of the beam space pointing positioning module 10 in the machine tool coordinate system can be obtained according to the E value;

Step 10. Adjust the position of the laser processing head so that the axis of the laser beam is parallel to the table surface of the C-axis 8 turntable, move the Z-axis 1, so that the calibration point in the visual interface coincides with the end face of the C-axis 8 turntable, and obtain the end face of the C-axis 8 turntable. The Z axis 1 coordinate value z, and then the XYZ machine tool coordinates (x, y, z) of the C axis 8 turntable are obtained, thereby establishing the coordinate relationship between the laser focus 24 and the C axis 8, thus laying the foundation for establishing the workpiece 9 coordinate system.

In this step, adjust the A-axis and B-axis to 0°, so that the axis of the focusing mirror is parallel to the table surface of the C-axis 8, move the Z-axis 1 up and down, so that the laser focus 24 in the visual interface coincides with the end face of the C-axis 8, thus obtaining C The Z-axis 1 coordinate value z of the end face of the shaft 8.

Claims (5)

1. a laser processing head space position calibration method of a six-axis five-linkage machine tool, is characterized in that, comprises the following steps: Step 1. Set a laser focus position calibration device on the laser processing head of the six-axis five-linkage machine tool, and the laser focus position calibration device includes a ranging sensor and a vision camera; Step 2. Set a detection plate on the C-axis turntable table of the six-axis five-linkage machine tool; Step 3: Move the ranging sensor to adjust the spatial attitude of the detection plate so that its surface is parallel to the plane of the XY axis; Step 4: Adjust the position of the laser processing head, make the laser beam perpendicular to the detection plate, and make the laser focus fall on the surface of the detection plate; Step 5: Adjust the position of the imaging surface of the vision camera, so that the vision camera has a clear image at the laser focus; Step 6: Rotate the C-axis turntable, and the laser beam emitted by the laser processing head forms a circular trajectory on the detection plate; Step 7. Move the X-axis and Y-axis of the six-axis five-linkage machine tool, so that the laser beam forms two parallel lines on the detection plate, and the two parallel lines intersect with the circular trajectory to obtain four intersection points J1, J2, J3, J4, at this time, the two parallel lines are located on the same side of the C-axis rotation center; Step 8. Move the X-axis and Y-axis of the six-axis five-linkage machine tool to find four intersection points through the visual camera, so that the laser focus in the visual interface coincides with the intersection points J1, J2, J3, and J4 respectively, and read the laser in the visual interface. Coordinates (x ₁ , y ₁ ), (x ₂ , y ₁ ), (x ₃ , y ₂ ), (x ₄ , y ₂ )) when the focus coincides with the intersection points J1, J2, J3, and J4; Step 9. Obtain the X and Y coordinates of the C-axis rotation center through the coordinates of the four laser focal points;

Step 10. Adjust the position of the laser processing head so that the axis of the laser beam is parallel to the table surface of the C-axis turntable, move the Z-axis so that the laser focus in the visual interface coincides with the end face of the C-axis turntable, and obtain the z-axis coordinate of the C-axis rotation center, Then, the XYZ machine coordinates (x, y, z) of the C-axis turntable are obtained, thereby establishing the coordinate relationship between the laser focus and the C-axis. 2. The method for calibrating the spatial position of the laser processing head of a six-axis five-linkage machine tool according to claim 1, wherein in step ten, adjust the A-axis and the B-axis to 0°, so that the focusing mirror axis of the laser processing head and The C-axis table is parallel, and the Z-axis is moved up and down to make the laser focus in the visual interface coincide with the C-axis end face, thereby obtaining the Z-axis coordinate value z of the C-axis end face. 3 . The method for calibrating the spatial position of a laser processing head of a six-axis five-linkage machine tool according to claim 2 , wherein in step 1, the vision camera is a coaxial vision camera or a paraxial vision camera. 4 . 4. The method for calibrating the spatial position of a laser processing head of a six-axis five-linkage machine tool according to claim 1, 2 or 3, characterized in that: in step 2, the flatness of the detection plate is within 0.02 mm. 5 . The method for calibrating the spatial position of a laser processing head for a six-axis five-linkage machine tool according to claim 4 , wherein in step 1, the ranging sensor is a range-finder sensor. 6 .

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