Correcting device for laser galvanometer of laser marking machine

Abstract

The utility model discloses a correcting device for a laser galvanometer of a laser marking machine, which comprises a main mounting assembly, a vertical mounting assembly is arranged on the main mounting assembly, a focusing adjustment control assembly is arranged on the vertical mounting assembly, a laser generation assembly is arranged at a moving part of the focusing adjustment control assembly, and a laser galvanometer is arranged on the laser generation assembly. A laser galvanometer is arranged at the output end of the laser generation assembly, a calibration assembly is arranged on the main installation assembly and located below the laser galvanometer, an auxiliary support is arranged on the laser galvanometer, and an image taking assembly is arranged on the auxiliary support. The beneficial effects of the device are that the device not only solves the problems of wrong input and time consumption encountered by a traditional correction mode, but also has the advantage of being comparable with high-precision measurement equipment in precision, and avoids the problem of complexity caused by manual data input in the measurement of the high-precision equipment.

Description

Technical Field

[0001] The utility model relates to the technical field of laser galvanometer correction, in particular to a correction device for a laser galvanometer of a laser marking machine. Background Art

[0002] The working principle of the galvanometer of the laser marking machine is to make the laser beam incident on two reflectors (scanning mirrors) and use a computer to control the reflection angle of the reflectors. The two reflectors can scan along the X and Y axes respectively, so as to achieve the deflection of the laser beam, so that the laser focus with a certain power density moves on the marking material as required, thereby leaving a permanent mark on the surface of the material. The laser scanner is also called a laser galvanometer, which consists of an XY optical scanning head, an electronic drive amplifier and an optical reflective lens. The signal provided by the computer controller drives the optical scanning head through the drive amplifier circuit, thereby controlling the deflection of the laser beam in the XY plane.

[0003] Industrial laser marking machine BOX calibration is usually for the laser coordinate system position calibration. After calibration, the laser marking position is consistent with the actual physical coordinate position. Now generally use ruler or vernier caliper measurement tools to measure the relative physical distance of the four corners of the laser-marked rectangular frame. When high precision is required, a three-dimensional device is used to measure the relative physical distance of the four corners of the laser-marked rectangular frame, and then the measurement results are input into the laser marking system to calibrate the laser marking coordinate system.

[0004] In summary, the above calibration methods have the following problems: 1. The calibration method is time-consuming and labor-intensive. After measuring the relative physical distance of the calibration points, the position coordinates of each point need to be manually input, which is very cumbersome. 2. Human errors often occur during the input of numbers, which is not easy for operators. 3. Accuracy and high cost issues. During manual measurement, visual errors are caused by the limitations of the human eye. When using high-precision three-dimensional measuring instruments for measurement, the purchase cost of the instrument is self-evident. Utility Model Content

[0005] The purpose of the utility model is to solve the above problems and to design a correction device for the laser galvanometer of a laser marking machine.

[0006] To achieve the above-mentioned purpose, the technical solution of the utility model is a correction device for the laser galvanometer of a laser marking machine, comprising a main mounting assembly, a vertical mounting assembly is arranged on the main mounting assembly, a focus adjustment control assembly is arranged on the vertical mounting assembly, a laser generating assembly is arranged at the moving part of the focus adjustment control assembly, a laser galvanometer is arranged at the output end of the laser generating assembly, a calibration assembly is arranged on the main mounting assembly below the laser galvanometer, an auxiliary bracket is arranged on the laser galvanometer, and a mapping assembly is arranged on the auxiliary bracket.

[0007] As a further description of the technical solution, the main installation component includes a main installation base plate, and a vertical installation component is arranged on the main installation base plate.

[0008] As a further description of the technical solution, the vertical mounting assembly includes a vertical mounting plate arranged on the main mounting assembly, and a focus adjustment control assembly is arranged on the vertical mounting plate.

[0009] As a further description of the present technical solution, the focus adjustment control component includes a focus adjustment control lifting module arranged on a vertical mounting component, and a laser generating component is arranged at a moving part of the focus adjustment control lifting module.

[0010] As a further description of the technical solution, the laser generating component includes a laser generator arranged at a moving part of the focus adjustment control component, and a laser galvanometer is arranged at the output end of the laser generator.

[0011] As a further description of the technical solution, the calibration component includes a calibration plate arranged on the main mounting component below the laser galvanometer, and the image taking component includes a shooting camera arranged on an auxiliary bracket.

[0012] A method for calibrating a laser galvanometer of a laser marking machine comprises the following steps:

[0013] Step 1: Install the industrial camera (12 megapixels) on the bracket, use the camera image acquisition software, and adjust the clarity of the camera lens (12mm) through the focus adjustment control component to make the displayed image the clearest, that is, at the camera shooting focal length;

[0014] Step 2: Place a visual calibration standard plate (e.g. a 7*7 circular calibration plate with a dot diameter of 7.5mm, a dot spacing of 15mm, and an accuracy of 0.01mm) under the industrial camera, move the calibration plate, and observe its position in the image field of view, so that it is in the center of the image and all the dots on the calibration plate are within the field of view, and fine-tune the camera focus to make the graphic features in the calibration plate clearest;

[0015] Step 3: Take a calibration plate image, use the visual algorithm to identify all the graphics in the calibration plate, and calculate the pixel coordinate values ​​of the center points of all the graphics;

[0016] Step 4: Install a fiber laser marking system platform commonly used in industrial laser marking systems; use a piece of paper that can be marked on it, use the marking effect presented on the paper, and adjust the marking focal length to achieve the best marking effect;

[0017] Step 5: Create a dot matrix image file with a dot diameter of 7*7 and a dot spacing of 15mm, for example, and use the marking system to mark the dot matrix on the marking paper;

[0018] Step 6: Place the marking paper with the dot matrix under the camera, take a picture, and identify the dots on the marking paper;

[0019] Step 7: The camera takes a picture of the laser-marked points and identifies the pixel coordinates of the laser-marked feature points. The laser coordinates of the laser-marked points are known, and the relationship R2 between the pixel coordinates and the laser coordinate system is established. According to the two coordinate relationships R1 and R2, the relationship R3 between the laser coordinate system and the physical coordinate system of the calibration plate can be obtained. R3 is input into the laser marking system to complete the laser BOX area calibration. This method eliminates the tedious steps of manual point input and avoids the tiny distance difference that cannot be distinguished by the naked eye, and can efficiently complete the laser BOX calibration. In actual industrial applications, the calibration camera can use a high-pixel camera, and the laser can be used to mark a larger number of dots with smaller diameters and smaller spacing to calibrate the BOX, and the accuracy can reach 0.01mm accuracy of the calibration plate.

[0020] As a further description of the present technical solution, in the step three, the center figure of the calibration plate, such as a circular calibration plate, is used, the center of the circle is the coordinate origin, the center of the middle row of circles is to the right in the X-axis direction, and the center of the middle column of circles is to the top in the Y-axis direction. The physical coordinates of the center of each circle of the calibration plate can be obtained from the dimensions marked on the calibration plate; according to the physical coordinates corresponding to the center coordinates of each figure of the calibration plate, the conversion relationship R1 from the pixel coordinate system of the camera to the physical coordinate system of the calibration plate is calculated.

[0021] As a further description of the technical solution, in step six, a visual algorithm is used to calculate the pixel coordinates of the center of each dot on the marking paper; the least squares method is used to fit the centers of the dots in the middle row into a straight line, and the distance from each point to the straight line is calculated. If the distance is greater than a certain set value (this set value is set with reference to the accuracy required by the customer), it can be judged that the axis accuracy corresponding to this galvanometer system is insufficient, and a perpendicular line is drawn to the fitted straight line with the center of the middle dot in the middle row, and the distance from the center of the dots in the middle column to the perpendicular line is calculated. If the distance is greater than a certain set value (this set value is set with reference to the accuracy required by the customer), it can be judged that the axis accuracy corresponding to this galvanometer system is insufficient, or the X-axis and Y-axis verticality accuracy of the galvanometer system is insufficient; in this way, it can be assisted in judging whether the control accuracy of the laser galvanometer system itself meets the standard, thereby reducing the generation of defective marking products due to problems with the laser galvanometer system.

[0022] As a further description of the technical solution, the physical coordinate matrix of the calibration plate is set to S[Xs Ys], the camera pixel coordinate matrix is ​​set to P[Xp Yp], the laser coordinate matrix is ​​set to L[XL YL], and the pixel coordinate matrix corresponding to the laser point is set to M[Xm Ym]. The general form of the affine transformation of the spatial coordinate transformation is as follows:

[0023]

[0024] Where T is the transformation matrix. According to this affine transformation, it can be concluded that S=P is the transformation matrix for converting pixel coordinate space into physical coordinate space, which can be calculated through the formula S=P, from which the physical coordinate matrix M of the laser dot can be obtained; similarly, M=L is the transformation matrix for converting laser coordinate space into physical coordinates, and the transformation matrix can also be calculated, based on which the physical coordinates of any point in the laser coordinate space can be obtained.

[0025] The beneficial effect is that the present invention not only solves the problems of incorrect input and time-consuming problems encountered in traditional calibration methods, but also has advantages in accuracy comparable to high-precision measurement equipment, avoiding the tedious problems caused by manual data input in high-precision equipment measurement.

[0026] The present invention uses an industrial camera in combination with a standard calibration plate as an aid, and relies on the high precision of the calibration plate to quickly and accurately calibrate the laser scanning galvanometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall structure of the correction device of the utility model;

[0028] Figure 2 It is a schematic diagram of the overall structure of the correction device of the utility model from another perspective.

[0029] In the figure, 1. Main mounting assembly; 2. Vertical mounting assembly; 3. Focus adjustment control assembly; 4. Laser generating assembly; 5. Laser galvanometer; 6. Calibration assembly; 7. Auxiliary bracket; 8. Image acquisition assembly; 9. Main mounting base plate; 10. Vertical mounting plate; 11. Focus adjustment control lifting module; 12. Laser generator; 13. Calibration plate; 14. Shooting camera. DETAILED DESCRIPTION

[0030] The utility model is described in detail below in conjunction with the accompanying drawings. Figure 1-Figure 2 As shown, a correction device for the laser galvanometer of a laser marking machine includes a main mounting component 1. The main mounting component 1 will be described in detail below. The main mounting component 1 includes a main mounting base plate 9, and a vertical mounting component 2 is arranged on the main mounting base plate 9.

[0031] In order to facilitate the installation of the focus adjustment control component 3, a vertical installation component 2 is arranged on the main installation component 1. The vertical installation component 2 will be described in detail below. The vertical installation component 2 includes a vertical installation plate 10 arranged on the main installation component 1, and the vertical installation plate 10 is provided with the focus adjustment control component 3.

[0032] In order to facilitate the focus adjustment of the industrial camera, a focus adjustment control component 3 is arranged on the vertical mounting component 2. The focus adjustment control component 3 will be described in detail below. The focus adjustment control component 3 includes a focus adjustment control lifting module 11 arranged on the vertical mounting component 2, and the moving part of the focus adjustment control lifting module 11 is provided with a laser generating component 4.

[0033] A laser generating component 4 is arranged at the moving part of the focus adjustment control component 3 . The laser generating component 4 includes a laser generator 12 arranged at the moving part of the focus adjustment control component 3 . A laser galvanometer 5 is arranged at the output end of the laser generator 12 .

[0034] A laser galvanometer 5 is arranged at the output end of the laser generating component 4. In order to facilitate the calibration of the laser galvanometer 5, a calibration component 6 is arranged on the main mounting component 1 below the laser galvanometer 5. The calibration component 6 will be described in detail below. The calibration component 6 includes a calibration plate 13 arranged on the main mounting component 1 below the laser galvanometer 5.

[0035] In order to facilitate the installation of the image taking component 8, an auxiliary bracket 7 is arranged on the laser galvanometer 5. In order to facilitate photo recording, an image taking component 8 is arranged on the auxiliary bracket 7. The image taking component 8 will be described in detail below. The image taking component 8 includes a shooting camera 14 arranged on the auxiliary bracket 7.

[0036] The calibration device is described in detail above. The calibration method of the laser galvanometer 5 of the laser marking machine is described in detail below, including the following steps:

[0037] Step 1: Install the industrial camera (12 megapixels) on the bracket, use the camera image acquisition software, and adjust the clarity of the image taken by the camera lens (12mm) through the focus adjustment control component 3 to make the displayed image the clearest, that is, at the camera shooting focal length;

[0038] Step 2: Place a visual calibration standard calibration plate 13 (e.g., a 7*7 circular calibration plate 13 with a dot diameter of 7.5mm, a dot spacing of 15mm, and an accuracy of 0.01mm) under the industrial camera, move the calibration plate 13, and observe its position in the image field of view, so that it is in the center of the image and all the dots on the calibration plate 13 are within the field of view, and fine-tune the camera focus to make the graphic features in the calibration plate 13 clearest;

[0039] Step three: take an image of the calibration plate 13, use the visual algorithm to identify all the graphics in the calibration plate 13, and calculate the pixel coordinate values ​​of the center points of all the graphics; in the step three, the center figure of the calibration plate 13, for example, a circular calibration plate 13, the center of the circle is the origin of the coordinates, the center of the circle in the middle row is to the right in the X-axis direction, and the center of the circle in the middle column is to the top in the Y-axis direction. The physical coordinates of the center of each circle of the calibration plate 13 can be obtained from the dimensions marked on the calibration plate 13; according to the physical coordinates corresponding to the center coordinates of each graphic on the calibration plate 13, the conversion relationship R1 from the pixel coordinate system of the camera to the physical coordinate system of the calibration plate 13 is calculated;

[0040] Step 4: Install a fiber laser marking system platform commonly used in industrial laser marking systems; use a piece of paper that can be marked on it, use the marking effect presented on the paper, and adjust the marking focal length to achieve the best marking effect;

[0041] Step 5: Create a dot matrix image file with a dot diameter of 7*7 and a dot spacing of 15mm, for example, and use the marking system to mark the dot matrix on the marking paper;

[0042] Step 6: Place the marking paper with the dot matrix under the camera, take a picture, and identify the dots on the marking paper; in step 6, use the visual algorithm to calculate the pixel coordinates of the center of each dot on the marking paper; use the least squares method to fit the centers of the dots in the middle row into a straight line, and calculate the distance from each point to the straight line. If the distance is greater than a certain set value (this set value is set with reference to the accuracy required by the customer), it can be judged that the axis accuracy corresponding to this galvanometer system is insufficient; use the center of the middle dot in the middle row to make a perpendicular line to the fitted straight line, and calculate the distance from the center of the middle column of dots to the perpendicular line. If the distance is greater than a certain set value (this set value is set with reference to the accuracy required by the customer), it can be judged that the axis accuracy corresponding to this galvanometer system is insufficient, or the X-axis and Y-axis verticality accuracy of the galvanometer system is insufficient; in this way, it can be assisted in judging whether the control accuracy of the laser galvanometer system itself meets the standard, thereby reducing the generation of defective marking products due to problems with the laser galvanometer system;

[0043] Step 7: The camera takes a picture of the laser-marked point and identifies the pixel coordinates of the laser-marked feature point. The laser coordinates of the laser-marked point are known, and the relationship R2 between the pixel coordinates and the laser coordinate system is established. According to the two coordinate relationships R1 and R2, the physical coordinate system relationship R3 between the laser coordinate system and the calibration plate 13 can be obtained. R3 is input into the laser marking system to complete the laser BOX area correction. This method eliminates the tedious steps of manual point input and avoids the tiny distance difference that cannot be distinguished by the naked eye, and can efficiently complete the laser BOX correction. In actual industrial applications, a high-pixel camera can be used as the calibration camera, and a laser can be used to mark a dot matrix with a larger number, a smaller dot diameter, and a smaller spacing to calibrate the BOX, and the accuracy can reach 0.01mm accuracy of the calibration plate 13.

[0044] The physical coordinate matrix of the calibration plate 13 is set to S[Xs Ys], the camera pixel coordinate matrix is ​​set to P[Xp Yp], the laser coordinate matrix is ​​set to L[XL YL], and the pixel coordinate matrix corresponding to the laser point is set to M[Xm Ym]. The general form of the affine transformation of the spatial coordinate transformation is as follows:

[0045]

[0046] Where T is the transformation matrix. According to this affine transformation, it can be concluded that S=P is the transformation matrix for converting pixel coordinate space into physical coordinate space, which can be calculated through the formula S=P, from which the physical coordinate matrix M of the laser dot can be obtained; similarly, M=L is the transformation matrix for converting laser coordinate space into physical coordinates, and the transformation matrix can also be calculated, based on which the physical coordinates of any point in the laser coordinate space can be obtained.

[0047] The above method is for the galvanometer marking range and the camera field of view in the same field of view. This method can be extended to the marking system with a paraxial installation, that is, the camera is installed outside the marking system platform. The specific steps for the galvanometer calibration of the marking system with a paraxial installation are as follows (the first six steps are similar to the above method):

[0048] Step A: Install the industrial camera (12 megapixels) on the bracket, and use the camera image acquisition software to adjust the clarity of the image taken by the camera lens (12mm) to make the displayed image the clearest, that is, at the camera shooting focal length.

[0049] Step B: Place a visual calibration standard plate (e.g. a 7*7 circular calibration plate with a dot diameter of 7.5mm, a dot spacing of 15mm, and an accuracy of 0.01mm) under the industrial camera, move the calibration plate, and observe its position in the image field of view, so that it is in the center of the image and all the dots on the calibration plate are within the field of view, and fine-tune the camera focus to make the graphic features in the calibration plate clearest.

[0050] Step C: Take an image of the calibration plate, use the visual algorithm to identify all the graphics in the calibration plate, calculate the pixel coordinate values ​​of the center points of all the graphics, and use the center graphics of the calibration plate, such as the circular calibration plate, as the coordinate origin. The center of the dots in the middle row is to the right in the X-axis direction, and the center of the dots in the middle column is to the top in the Y-axis direction. The physical coordinates of the center of each dot of the calibration plate can be obtained from the dimensions marked on the calibration plate. According to the physical coordinates corresponding to the center coordinates of each graphic on the calibration plate, calculate the conversion relationship R1 from the pixel coordinate system of the camera to the physical coordinate system of the calibration plate.

[0051] Step D: Install a fiber laser marking system platform commonly used in industrial laser marking systems. Use a piece of paper to mark on, use the marking effect presented on the paper, and adjust the marking focal length to achieve the best marking effect.

[0052] Step E: Create a dot matrix image file with, for example, 7*7 dots with a diameter of 7.5mm and a dot spacing of 15mm, and use the marking system to mark this dot matrix on the marking paper.

[0053] Step F: Place the marking paper with the dot matrix under the camera, take a picture, identify the dots on the marking paper, and use the visual algorithm to calculate the pixel coordinates of the center of each dot on the marking paper. Using the least squares method, fit the centers of the dots in the middle row into a straight line, and calculate the distance from each point to the straight line. If the distance is greater than 0.02mm, it can be determined that there is a problem with the galvanometer system in this laser marking system. Draw a perpendicular line to this fitted straight line from the center of the middle dot in the middle row, and calculate the distance from the center of the dots in the middle column to the perpendicular line. If the distance is greater than 0.02mm, it can be determined that there is a problem with the galvanometer system in this laser marking system. In this way, it can assist in determining whether there is a problem with the laser galvanometer system and reduce the production of defective marking products due to problems with the laser galvanometer system.

[0054] Step G: Based on the straight line fitted by the center of the middle row of dots obtained in step 6, calculate the rotation angle A of this straight line, rotate the physical coordinate system established in step 3 to be parallel to the X-axis and the fitted straight line, and then translate the origin of the physical coordinate system to the center of the middle dot in the middle row of step 6. After rotation and translation, the physical coordinate system and the laser coordinate system are consistent. Assume that the conversion relationship of this rotation and translation is R4.

[0055] Step H: The camera takes a picture of the laser-marked point, identifies the pixel coordinates of the laser-marked feature point, and establishes the relationship R2 between the pixel coordinates and the laser coordinate system, given the laser coordinates of the laser-marked point. Based on the two coordinate relationships R1 and R2, the relationship R3 between the laser coordinate system and the physical coordinate system of the calibration plate can be obtained. Then, the center coordinates of each dot in the dot matrix obtained from R3 and R4 are input into the laser marking system to complete the calibration of the galvanometer BOX area of ​​the paraxial laser marking system.

[0056] The present invention not only solves the problems of erroneous input and time-consuming problems encountered in traditional calibration methods, but also has advantages in accuracy comparable to high-precision measurement equipment, avoiding the cumbersome problems caused by manual data input in high-precision equipment measurement.

[0057] The present invention uses an industrial camera in combination with a standard calibration plate as an aid, and relies on the high precision of the calibration plate to quickly and accurately calibrate the laser scanning galvanometer.

[0058] The above technical solutions only reflect the preferred technical solutions of the technical solutions of the utility model. Some changes that may be made to certain parts thereof by technicians in this technical field all reflect the principles of the utility model and fall within the protection scope of the utility model.

Claims

1. A calibration device for a laser galvanometer of a laser marking machine, characterized in that: The invention comprises a main mounting component (1), wherein a vertical mounting component (2) is arranged on the main mounting component (1), wherein a focus adjustment control component (3) is arranged on the vertical mounting component (2), wherein a laser generating component (4) is arranged at a movable part of the focus adjustment control component (3), wherein a laser galvanometer (5) is arranged at an output end of the laser generating component (4), wherein a calibration component (6) is arranged on the main mounting component (1) below the laser galvanometer (5), wherein an auxiliary bracket (7) is arranged on the laser galvanometer (5), and wherein an image taking component (8) is arranged on the auxiliary bracket (7).

2. The calibration device for the laser galvanometer of a laser marking machine according to claim 1, characterized in that: The main installation component (1) comprises a main installation base plate (9), and a vertical installation component (2) is arranged on the main installation base plate (9).

3. The calibration device for a laser galvanometer of a laser marking machine according to claim 1, characterized in that: The vertical mounting assembly (2) comprises a vertical mounting plate (10) arranged on the main mounting assembly (1), and a focus adjustment control assembly (3) is arranged on the vertical mounting plate (10).

4. The calibration device for a laser galvanometer of a laser marking machine according to claim 1, characterized in that: The focus adjustment control component (3) comprises a focus adjustment control lifting module (11) arranged on a vertical mounting component (2), and a laser generating component (4) is arranged at a moving part of the focus adjustment control lifting module (11).

5. The calibration device for the laser galvanometer of a laser marking machine according to claim 1, characterized in that: The laser generating component (4) comprises a laser generator (12) arranged at a moving part of the focus adjustment control component (3), and a laser galvanometer (5) is arranged at the output end of the laser generator (12).

6. The calibration device for a laser galvanometer of a laser marking machine according to claim 1, characterized in that: The calibration component (6) comprises a calibration plate (13) arranged on the main mounting component (1) below the laser galvanometer (5), and the image acquisition component (8) comprises a shooting camera (14) arranged on the auxiliary bracket (7).

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