Correction method and correction system for scanning galvanometer of laser powder bed melting equipment

Abstract

The invention relates to a method and system for correcting a scanning galvanometer of laser powder bed melting equipment, and the method comprises the steps: analyzing the image data of a camera calibration plate, and obtaining a first parameter; printing a target image on the laser printing paper according to a preset coordinate position; the transparent standard plate is placed on the laser printing paper printed with the target image, the transparent standard plate and the laser printing paper are aligned at the center point position of the original point calibration point, and the target image is obtained; calculating a second parameter in combination with the first parameter and the target image; fitting the coordinates of the target image calibration point and the calibration point of the transparent standard plate in the world coordinate system in combination with the second parameter, comparing the preset coordinate position, and calculating a fitting error; compensating the fitting error to the coordinate of the target image calibration point in the world coordinate system, comparing with the preset coordinate position, and calculating the position deviation; and correcting the galvanometer system according to the position deviation. According to the invention, the correction precision of the galvanometer system can be improved through accurate correction parameter acquisition and galvanometer module adjustment.

Description

Technical Field

[0001] The present invention relates to the technical field of laser scanning galvanometer correction, and in particular to a correction method and a correction system for a scanning galvanometer of a laser powder bed melting device. Background Art

[0002] Laser Powder Bed Fusion (LPBF) is a technology widely used in additive manufacturing. It uses a laser beam to melt the powder bed layer by layer to form a complex three-dimensional structure. The scanning galvanometer is a key component that controls the scanning path of the laser beam. Its correction accuracy directly affects the quality and manufacturing efficiency of the final product.

[0003] Existing galvanometer correction methods mainly rely on manual adjustment or simple automated correction systems. Manual adjustment often has a complex and time-consuming calibration process, while simple automated correction systems have the problem of insufficient correction accuracy, which is difficult to meet the needs of high-precision manufacturing. The Chinese invention patent with publication number CN112810137A discloses a method and system for calibrating the scanning galvanometer of a laser powder plant melting equipment. The laser prints the calibration image, aligns and compares it with the image of a transparent calibration plate with scales, obtains the position deviation of each calibration point, and calibrates the galvanometer according to the position deviation. The back end of this solution uses manual measurement of the error range. After calibration, the scanning accuracy of the galvanometer can reach 0.1mm. In actual printing, the calibration error is still too large.

[0004] Therefore, there is an urgent need for a solution that can improve the calibration accuracy of the galvanometer and simplify the calibration process. Summary of the invention

[0005] The object of the present invention is to provide a calibration method and a calibration system for a scanning galvanometer of a laser powder bed melting device, which can solve the problem of low calibration accuracy mentioned in the above background technology.

[0006] To achieve the above object, the first aspect of the present invention provides a calibration method for a scanning galvanometer of a laser powder bed melting device, comprising the following steps:

[0007] Analyze and calculate the image data of the camera calibration plate to obtain the first parameter;

[0008] Printing the target image on the laser printing paper according to the preset coordinate position;

[0009] Place the transparent standard plate on the laser printing paper on which the target image has been printed, align the transparent standard plate and the center point of the laser printing paper at the origin calibration point, and obtain the target image;

[0010] Combining the first parameter with the target image, calculating a second parameter;

[0011] In combination with the second parameter, coordinates of the calibration points of the target image and the calibration points on the transparent standard plate in the world coordinate system are fitted, the preset coordinate positions are compared, and the fitting error is calculated;

[0012] The fitting error is compensated to the coordinates of the target image calibration point in the world coordinate system, and finally compared with the preset coordinate position to calculate the position deviation of the target image mark point;

[0013] The galvanometer system is calibrated according to the position deviation.

[0014] In a preferred embodiment, during the process of acquiring the image data of the camera calibration plate, the camera calibration plate is moved along the first direction and the second direction, and its image data is collected.

[0015] In a preferred embodiment, the camera calibration plate is in a checkerboard shape or a solid circle shape, and the number of rows and columns are inconsistent.

[0016] In a preferred embodiment, the calibration points on the transparent standard plate are in the shape of a cross or a circular matrix.

[0017] In a preferred embodiment, the step of obtaining the second parameter is specifically to process the target image, calculate the coordinate positions of the calibration points of the target image and the coordinate positions of the calibration points on the transparent standard plate based on the affine transformation of the dual coordinate system, and calculate the second parameter by combining the first parameter and the coordinate positions of the calibration points on the transparent standard plate.

[0018] In a preferred embodiment, the control points are selected based on the feature analysis of the covariance matrix in combination with the first parameter and the coordinate position of the calibration point of the target image:

[0019] The coordinate position of the target image calibration point is recorded as P = {p 1 , p 2 , ..., p n}, where the coordinates of each point are P i =[x i ;y i ;z i ], calculate the center point μ, and centralize the data:

[0020]

[0021] The covariance matrix ∑ reflects the distribution characteristics of the data in each direction:

[0022]

[0023] Among them, Q is the data matrix after removing the mean.

[0024] In a preferred embodiment, the calibration step of the galvanometer system includes:

[0025] The maximum value of the position deviation is compared with a preset error threshold. If the maximum value of the position deviation is greater than the preset error threshold, the galvanometer system is calibrated until the maximum value of the position deviation is no greater than the error threshold, and the correction is stopped.

[0026] A second aspect of the present invention provides a calibration system for a scanning galvanometer of a laser powder bed melting device, comprising:

[0027] A laser module, used for providing a laser beam;

[0028] The galvanometer module is used to receive the laser beam provided by the laser module and perform laser path scanning;

[0029] An image acquisition module is used to acquire the camera calibration plate image and the target image generated by the laser on the laser printing paper;

[0030] A camera calibration module, which calculates a first parameter according to the camera calibration plate image data acquired by the image acquisition module;

[0031] An image processing module, which calculates the second parameter, the fitting error and the position deviation according to the laser target image and the transparent standard plate image acquired by the image acquisition module;

[0032] The galvanometer correction module is used to calibrate the galvanometer system.

[0033] A third aspect of the present invention provides a calibration device for a scanning galvanometer of a laser powder bed melting device, the device comprising:

[0034] Memory: used to store computer programs;

[0035] Processor: used to implement the calibration method for the scanning galvanometer of the laser powder bed melting equipment described in the above scheme when executing the computer program.

[0036] A fourth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the scanning galvanometer calibration method for laser powder bed melting equipment described in the aforementioned scheme are implemented.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The correction method and correction system for the scanning galvanometer of laser powder bed melting equipment provided by the present invention are intended to improve the correction accuracy of the galvanometer system by accurately acquiring correction parameters and adjusting the galvanometer module. By acquiring the first parameter, the error of the image acquisition module can be corrected; by acquiring the first parameter, the second parameter, and the coordinate position of the calibration point on the transparent standard plate, the coordinates of the calibration point on the transparent standard plate in the world coordinate system can be fitted, and the fitting error can be obtained by comparing with the preset coordinate position. The compensation of the two errors for the calculation results can greatly improve the accuracy range of the results and greatly reduce the number of repeated corrections. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a flow chart of a scanning galvanometer calibration method for laser powder bed melting equipment in an embodiment of the present invention;

[0040] Figure 2 is a schematic diagram of a transparent standard plate in an embodiment of the present invention;

[0041] Figure 3 is a schematic diagram of a camera correction plate according to an embodiment of the present invention;

[0042] Figure 4 It is a schematic diagram of aligning a transparent standard plate with a laser printing plate in an embodiment of the present invention;

[0043] Figure 5 Schematic diagram of a calibration device for a scanning galvanometer of a laser powder bed melting device according to an embodiment of the present invention

[0044] Figure 6 Schematic diagram of error accuracy of the scanning galvanometer before correction in an embodiment of the present invention;

[0045] Figure 7 Schematic diagram of the error accuracy of the scanning galvanometer after correction in an embodiment of the present invention. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0048] See also Figure 1 The first aspect of the present invention discloses a calibration method for a scanning galvanometer of a laser powder bed melting device, comprising the following steps:

[0049] Analyze and calculate the image data of the camera calibration plate to obtain the first parameter;

[0050] Printing the target image on the laser printing paper according to the preset coordinate position;

[0051] Place the transparent standard plate on the laser printing paper on which the target image has been printed, align the transparent standard plate and the center point of the laser printing paper at the origin calibration point, and obtain the target image;

[0052] Combining the first parameter with the target image, calculating a second parameter;

[0053] In combination with the second parameter, coordinates of the calibration points of the target image and the calibration points on the transparent standard plate in the world coordinate system are fitted, the preset coordinate positions are compared, and the fitting error is calculated;

[0054] The fitting error is compensated to the coordinates of the target image calibration point in the world coordinate system, and finally compared with the preset coordinate position to calculate the position deviation of the target image mark point;

[0055] The galvanometer system is calibrated according to the position deviation.

[0056] The calculation of the first parameter is used for camera calibration, and the calculation method includes but is not limited to Zhang calibration method. Specifically, firstly, a camera calibration plate in the shape of a chessboard or a solid circle is prepared, such as Figure 3 As shown, the number of rows and columns of the camera calibration plate are inconsistent; image data of the camera calibration plate is collected to ensure that the camera calibration plate is within the field of view of the camera, the camera calibration plate is moved along a first direction and a second direction, and multiple images are collected, wherein the first direction and the second direction are perpendicular; then the collected image data of the camera calibration plate are analyzed and calculated according to Zhang's calibration method to obtain a first parameter.

[0057] The laser printing paper is pasted on the laser printing plate, which is placed under the galvanometer module to print the target image according to the preset coordinate position.

[0058] In the above step of acquiring the target image, the material of the transparent standard plate used includes but is not limited to glass, plastic, such as Figure 2 As shown, the transparent standard plate is provided with specific marks in the shape of a cross or a circular matrix, and the transparent standard plate is used as a reference for galvanometer calibration. Align the transparent standard plate and the laser printing plate at the center point of the origin calibration point, as well as the first direction and the second direction where the origin is located. The alignment state is as shown in FIG. Figure 4 As shown, the aligned transparent standard plate and the laser printed plate are imaged to obtain a target image.

[0059] The calculation method of the above-mentioned second parameter includes but is not limited to the PnP solution method. Specifically, the acquired target image is processed to obtain the image coordinate position of the center of the circular array on the target image and the image coordinate position of the center point of the cross mark. Based on the coordinates of the center point of the circle and the coordinates of the center point of the cross mark, the center position of the circular array image of the target image is mapped using the affine transformation of the dual coordinate system and the coordinates of the center point of the cross mark as the reference. At the same time, the fitting error of the camera internal parameter can be calculated and incorporated into the calculation error of the galvanometer correction to increase the accuracy of the calculation result; the second parameter is calculated by combining the first parameter and the coordinate position of the cross mark point on the target image. The specific method is as follows:

[0060] Combined with the world coordinates of the cross mark of the target image, the existing fixed selection of centroid and principal component direction method is optimized, and the control point is selected based on the characteristic analysis of the covariance matrix; the confidence weighted improvement method assigns different weights according to the 3D point measurement error or depth information, improves the accuracy in a noisy environment, and establishes a new local coordinate system;

[0061] Combined with the image coordinates of the cross mark of the target image, using the camera projection model, a linear equation group about the coordinates of the control point in the camera coordinate system is established;

[0062] Solve the system of equations to calculate the second parameter.

[0063] According to the first parameter, the second parameter, the coordinate position of the calibration point of the target image, and the coordinate position of the calibration point on the transparent standard plate, the coordinates of the calibration point of the target image in the world coordinate system and the coordinates of the calibration point on the transparent standard plate in the world coordinate system are fitted respectively; according to the world coordinate (preset coordinate position) and the world coordinate of the calibration point on the transparent standard plate, a fitting error is obtained;

[0064] The fitting error is used to compensate the coordinates of the target image calibration point in the world coordinate system, and finally compared with the world coordinates (preset coordinate position) to obtain the position deviation of the galvanometer (i.e. the position deviation between the world coordinates of the target image calibration point and the preset coordinates).

[0065] The calibration steps for the galvanometer system include:

[0066] The maximum value of the position deviation is compared with a preset error threshold. If the maximum value of the position deviation is greater than the preset error threshold, the galvanometer system is calibrated until the maximum value of the position deviation is no greater than the error threshold, and the correction is stopped.

[0067] The second invention of the present invention discloses a calibration system for a scanning galvanometer of a laser powder bed melting device, comprising the following modules:

[0068] Laser module: used to provide a stable laser beam and emit laser to the galvanometer module to achieve precise laser scanning;

[0069] Galvanometer module: used to receive the laser beam provided by the laser module and perform high-precision laser path scanning according to the preset calibration point coordinate position;

[0070] Image acquisition module: equipped with a high-resolution camera of more than 25 million pixels, used to acquire the camera calibration plate image and the target image generated by the laser on the laser printing paper;

[0071] Camera calibration module: calculates the first parameter according to the camera calibration plate image data acquired by the image acquisition module;

[0072] Image processing module: according to the laser target image acquired by the image acquisition module, the coordinate position of the calibration point of the target image is calculated based on the Hough transform, a cross template is established based on template matching, and convolution is performed with the laser target image to calculate the coordinate position of the calibration point on the transparent standard plate, and the second parameter is calculated based on the improved PnP solution algorithm in combination with the first parameter and the coordinate position of the calibration point on the transparent standard plate; finally, the fitting error is calculated in combination with the first parameter and the second parameter, and the coordinate of the calibration point of the target image in the world coordinate system is compensated by the fitting error to obtain the position deviation of the galvanometer;

[0073] The galvanometer correction module corrects the galvanometer system according to the position deviation.

[0074] The correction method provided by the present invention is further described in detail below in conjunction with the embodiments. It should also be understood that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by technicians in this field according to the above content of the present invention all belong to the scope of protection of the present invention.

[0075] The present embodiment discloses a method for calibrating a scanning galvanometer of a laser powder bed melting device, comprising the following steps:

[0076] S1, collect the camera calibration plate image:

[0077] Collect image data of the camera calibration plate, ensure that the camera calibration plate is within the field of view of the camera, move the camera calibration plate along a first direction and a second direction perpendicular to each other, and collect 5 images;

[0078] S2, calculate the first parameter:

[0079] Analyze and calculate the five image data of the camera calibration plate according to Zhang's calibration method to obtain the first parameter;

[0080] S3, print target image:

[0081] The laser printing paper is attached to the laser printing plate, which is placed under the galvanometer module to print the target image according to the preset coordinate position;

[0082] S4, obtain target image:

[0083] Align the transparent standard plate and the laser printing plate at the center point of the origin calibration point, collect images of the aligned transparent standard plate and the laser printing plate, and obtain a target image;

[0084] S5, calculate the second parameter:

[0085] The acquired target image is processed to obtain the image coordinate position of the center of the circle array on the target image and the image coordinate position of the center point of the cross mark, as shown in Table 1, Table 2, Table 3 and Table 4 respectively:

[0086] Table 1 X coordinates of the center position of the cross-marking point

[0087] 4599.99951195705 5307.00048828125 6013.00098667982 4607.00099403579 5314 6019.99950592885 4614.00150300601 5320.00200601805 6026.00049825610

[0088] Table 2 Y coordinate of the center position of the cross mark point

[0089] 5088.00097656250 5079.99950666009 5072.00298359025 5793.00537897311 5786 5777.99749874937 6498.00702106319 6490.00498256104 6482.00249500998

[0090] Table 3 X coordinates of the center position

[0091] 4608.44900770358 5309.38862160561 6012.37150141736 4614.71511063950 5316.63963657832 6019.07780367489 4622.03740519362 5323.24807706644 6025.47862286784

[0092] Table 4 Y coordinate of the center position

[0093] 5100.82738960173 5092.63682198036 5084.94256699547 5799.94329694843 5792.27417223737 5784.40119537569 6497.35178364609 6490.44316840542 6481.82193510499

[0094] Based on the coordinates of the center point of the circle and the center point of the cross mark, the affine transformation of the dual coordinate system is used to calculate the coordinate position of the calibration point of the target image circle array after affine transformation, and for the two-dimensional point (x, y), the homogeneous coordinates are used to represent it as (x, y, 1). The affine transformation matrix is:

[0095]

[0096] Among them, the upper left corner 2×2 matrix Represents a linear transformation (such as rotation, scaling, translation). The translation vector (t x ,t y ) represents the translation component.

[0097] The transformed coordinates (x′, y′) are calculated as follows:

[0098] x′=a·x+b·y+t x

[0099] y′=c·x+d·y+t y

[0100] The results are shown in Tables 5 and 6:

[0101] Table 5 X coordinates of the center position after transformation

[0102] 4605.32365148415 5306.032541987952 6009.9513874254 4611.71511063950 5314 6016.2184896513 4619.987416124541 5320.0021456416487 6022.9410347498

[0103] Table 6 Y coordinate of the center position after transformation

[0104] 5099.56985624512 5091.1349859181354 5083.46251789415 5798.95412311514 5786 5783.12265484121 6496.23448416747 6489.84513474785 6480.15446574913

[0105] Combined with the first parameter and the coordinate position of the cross calibration point on the target image, the existing method of fixed selection of centroid and principal component direction is optimized, and control points are selected based on the characteristic analysis of the covariance matrix. This method makes the data more stable and avoids improper selection of control points caused by fixed selection of centroid, which leads to increased errors.

[0106] The coordinates of the cross-marked points on the target image are recorded as P = {p 1 , p 2 , ..., p n}, where the coordinates of each point are P i =[x i ;y i ;z i ] Calculate the center point μ and center the data:

[0107]

[0108] The covariance matrix ∑ reflects the distribution characteristics of the data in each direction:

[0109]

[0110] Where Q is the data matrix after removing the mean.

[0111] The confidence weighted improvement method assigns different weights according to the 3D point measurement error or depth information to improve the accuracy in a noisy environment and establish a new local coordinate system; combines the image coordinates of the cross mark of the target image, uses the camera projection model, and establishes a linear equation group about the coordinates of the control point in the camera coordinate system; solves the equation group and calculates the second parameter;

[0112] The camera internal parameters are as follows:

[0113]

[0114] Among them, f x and f y is the focal length, c x and c y is the offset of the camera optical axis center in the image coordinate system.

[0115] The projection equation is:

[0116]

[0117] Eliminate the scale factor s and get the image coordinate equation:

[0118]

[0119] After expansion, we get the linear equation system:

[0120]

[0121] The unknown vector is set as:

[0122]

[0123] Each control point generates two equations, which are organized into a matrix form Ax=0, where each row of the matrix A corresponds to an equation. For example, the row corresponding to the i-th control point is:

[0124]

[0125] Solve the least squares problem and orthogonalize the rotation matrix to get:

[0126]

[0127] The final second parameter formula is:

[0128]

[0129] S6, calculate the fitting error:

[0130] According to the first parameter, the second parameter, the coordinate position of the calibration point of the target image, and the coordinate position of the calibration point on the transparent standard plate, the coordinates of the calibration point of the target image in the world coordinate system are fitted, as shown in Table 7 and Table 8; the coordinates of the calibration point on the transparent standard plate in the world coordinate system; according to the world coordinates (preset coordinate positions) and the world coordinates of the calibration point on the transparent standard plate, the fitting errors are obtained as shown in Table 9 and Table 10;

[0131] Table 7 Circle center position X world coordinates

[0132] 4608.44900770358 5309.38862160561 6012.37150141736 4614.71511063950 5316.63963657832 6019.07780367489 4622.03740519362 5323.24807706644 6025.47862286784

[0133] Table 8 Y world coordinates of the center position of the circle

[0134] -19.9337009691328 -0.0191838451611242 19.9264072940370 -19.9250417783595 -0.0256652998585495 19.9201490480749 -19.9059089990738 -0.0125325117625058 19.8937528037254

[0135] Table 9 Fitting error X world coordinate

[0136] -0.0662990308672278 0.0191838451611242 0.0735927059630441 -0.0749582216405464 0.0256652998585495 0.0798509519251276 -0.0940910009261593 0.0125325117625058 0.106247196274641

[0137] Table 10 Fitting error Y world coordinate

[0138] 0.132056028227712 0.139869630828116 0.158907671836346 -0.0199347559549961 -0.0456027171168107 -0.0491798265594612 -0.213553186027404 -0.232272486943746 -0.231981400507504

[0139] S7, calculate the position deviation:

[0140] The fitting error is used to compensate the coordinates of the target image calibration points in the world coordinate system, and finally compared with the preset coordinate position to calculate the position deviation of the target image marking point as shown in Table 11 and Table 12;

[0141] Table 11 Position deviation X world coordinate

[0142] -0.0919643307257773 -0.00648145469742528 0.0479274061044946 -0.100623521499096 0 0.0541856520665781 -0.119756300784709 -0.0131327880960437 0.0805818964160912

[0143] Table 12 Position deviation world coordinates

[0144] 0.177658745344523 0.185472347944927 0.204510388953156 0.0256679611618146 0 -0.00357710944265053 -0.167950468910594 -0.186669769826935 -0.186378683390693

[0145] S8, calibration:

[0146] The galvanometer system is calibrated according to the position deviation, and the maximum value of the position deviation is compared with a preset error threshold. If the maximum value of the position deviation is greater than the preset error threshold, the galvanometer system is calibrated until the maximum value of the position deviation is no greater than the error threshold, and the correction is stopped.

[0147] In this embodiment, before calibration, the maximum error of the galvanometer is 1.752 mm. Figure 6As shown in the figure, after correction, the maximum error of the galvanometer is 0.08mm. Figure 7 shown.

[0148] The third aspect of the present invention also provides a calibration device for a scanning galvanometer of a laser powder bed melting device, Figure 5 The device may include one or more of the following components: a memory, a processor, and one or more computer programs, wherein the one or more computer programs may be stored in the memory and configured to be executed by one or more processors, and the one or more computer programs are configured to execute the aforementioned correction method for the scanning galvanometer of the laser powder bed melting device.

[0149] The memory may include a random access memory (RAM) or a read-only memory (ROM). The memory may be used to store instructions, programs, codes, code sets or instruction sets. The memory may include a program storage area and a data storage area, wherein the program storage area may store instructions for implementing an operating system, instructions for implementing at least one function, instructions for implementing the aforementioned method embodiment, etc.

[0150] The processor may include one or more processing cores. The processor uses various interfaces and lines to connect the various parts of the entire device, and executes various functions of the device and processes data by running or executing instructions, programs, code sets or instruction sets stored in the memory, and calling data stored in the memory. Optionally, the processor can be implemented in at least one hardware form of digital signal processing (DSP), field-programmable gate array (FPGA), and programmable logic array (PLA). The processor can integrate one or a combination of a central processing unit (CPU) and a modem. Among them, the CPU mainly processes the operating system and application programs; the modem is used to process wireless communications. It can be understood that the above-mentioned modem may not be integrated into the processor, but may be implemented separately through a communication chip.

[0151] The present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the calibration method for a scanning galvanometer of a laser powder bed melting device described in any of the above-mentioned embodiments of the invention is implemented. The rest of the content can refer to the prior art and will not be described in detail here.

[0152] Professionals may further appreciate that the various steps described in conjunction with the embodiments disclosed herein can be implemented with electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0153] The correction method and correction system for the scanning galvanometer of laser powder bed melting equipment provided by the present invention are intended to improve the correction accuracy of the galvanometer system by accurately acquiring correction parameters and adjusting the galvanometer module. By acquiring the first parameter, the error of the image acquisition module can be corrected; by acquiring the first parameter, the second parameter, and the coordinate position of the calibration point on the transparent standard plate, the coordinates of the calibration point on the transparent standard plate in the world coordinate system can be fitted, and the fitting error can be obtained by comparing with the preset coordinate position. The compensation of the two errors for the calculation results can greatly improve the accuracy range of the results and greatly reduce the number of repeated corrections.

[0154] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A calibration method for a scanning galvanometer of a laser powder bed melting device, characterized in that: The following steps are involved: Analyze and calculate the image data of the camera calibration plate to obtain the first parameter; Printing the target image on the laser printing paper according to the preset coordinate position; Place the transparent standard plate on the laser printing paper on which the target image has been printed, align the transparent standard plate and the center point of the laser printing paper at the origin calibration point, and obtain the target image; Combining the first parameter with the target image, calculating a second parameter; In combination with the second parameter, coordinates of the calibration points of the target image and the calibration points on the transparent standard plate in the world coordinate system are fitted, the preset coordinate positions are compared, and the fitting error is calculated; The fitting error is compensated to the coordinates of the target image calibration point in the world coordinate system, and finally compared with the preset coordinate position to calculate the position deviation of the target image mark point; The galvanometer system is calibrated according to the position deviation.

2. The calibration method for a scanning galvanometer of a laser powder bed melting device according to claim 1, characterized in that: The camera calibration plate is moved along the first direction and the second direction, and image data thereof is collected.

3. The calibration method for a scanning galvanometer of a laser powder bed melting device according to claim 1, characterized in that: The camera calibration plate is in a chessboard shape or a solid circle shape, and the number of rows and columns is inconsistent.

4. The calibration method for a scanning galvanometer of a laser powder bed melting device according to claim 1, characterized in that: The calibration points on the transparent standard plate are in the shape of a cross or a circular matrix.

5. The calibration method for a scanning galvanometer of a laser powder bed melting device according to claim 1, characterized in that: The step of obtaining the second parameter is specifically to process the target image, calculate the coordinate positions of the calibration points of the target image and the coordinate positions of the calibration points on the transparent standard plate based on the affine transformation of the dual coordinate system, and calculate the second parameter by combining the first parameter and the coordinate positions of the calibration points on the transparent standard plate.

6. The calibration method for a scanning galvanometer of a laser powder bed melting device according to claim 5, characterized in that: Combining the first parameter and the coordinate position of the calibration point of the target image, the control point is selected based on the characteristic analysis of the covariance matrix: The coordinate position of the target image calibration point is recorded as P = {p1, p2, ..., p n }, where the coordinates of each point are P i =[x i ;y i ; z i ], calculate the center point μ, and centralize the data: The covariance matrix ∑ reflects the distribution characteristics of the data in each direction: Among them, Q is the data matrix after removing the mean.

7. The calibration method for a scanning galvanometer of a laser powder bed melting device according to claim 1, characterized in that: The calibration steps for the galvanometer system include: The maximum value of the position deviation is compared with a preset error threshold. If the maximum value of the position deviation is greater than the preset error threshold, the galvanometer system is calibrated until the maximum value of the position deviation is no greater than the error threshold, and the correction is stopped.

8. A calibration system for a scanning galvanometer of a laser powder bed melting device, characterized in that: include: A laser module, used for providing a laser beam; The galvanometer module is used to receive the laser beam provided by the laser module and perform laser path scanning; An image acquisition module is used to acquire the camera calibration plate image and the target image generated by the laser on the laser printing paper; A camera calibration module, which calculates a first parameter according to the camera calibration plate image data acquired by the image acquisition module; An image processing module, which calculates the second parameter, the fitting error and the position deviation according to the laser target image and the transparent standard plate image acquired by the image acquisition module; The galvanometer correction module is used to calibrate the galvanometer system.

9. A calibration device for a scanning galvanometer of a laser powder bed melting device, characterized in that: The device comprises: Memory: used to store computer programs; Processor: used to implement the calibration method for the scanning galvanometer of laser powder bed melting equipment as described in any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the calibration method for a scanning galvanometer of a laser powder bed melting device as claimed in any one of claims 1 to 7 are implemented.

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