Automatic calibration and printing monitoring device and method for selective laser melting forming equipment

Abstract

The invention relates to the technical field of selective laser melting, in particular to an automatic calibration and printing monitoring device and method for selective laser melting forming equipment. The forming cylinder is arranged in the forming cavity, a scraper frame is arranged above the forming cylinder, and the scraper frame is used for installing a powder laying scraper; and the base plate is connected to the forming cylinder and can be driven by the forming cylinder, and the scraper is made to spread powder on the surface of the base plate layer by layer through layer-by-layer descending. Through automatic leveling of the integrated substrate, in-situ light path calibration based on the production substrate and a single-camera double-light-path automatic switching monitoring system, a traditional low-efficiency mode depending on manpower, external instruments and off-line operation is improved, the equipment preparation time is shortened from several hours to ten minutes, and the production efficiency is improved. The galvanometer and splicing calibration precision is stably improved to the micron level, and the consistency and traceability of the technological process are guaranteed through integrated continuous monitoring.

Description

Technical Field

[0001] This invention relates to the field of laser selective melting technology, and more specifically to an automatic calibration and printing monitoring device and method for laser selective melting forming equipment. Background Technology

[0002] Selective laser melting (SLM) technology, as a core method in high-end metal additive manufacturing, has been widely used in aerospace, medical devices, and other fields. With the increasing size and complexity of parts, multi-laser collaborative forming equipment has become mainstream, but this places higher demands on the precision, efficiency, and automation level of these devices.

[0003] Currently, the operation of such equipment still heavily relies on the experience and manual intervention of operators, as exemplified by the galvanometer dimensional accuracy calibration method disclosed in CN119714063A and the multi-laser rapid overlapping method for additive manufacturing equipment disclosed in CN119426617A. Before printing, substrate leveling and optical path calibration must be performed manually, a tedious and time-consuming process, and the accuracy is significantly affected by human factors. During printing, there are limited means to monitor powder spreading quality, molten pool state, and forming defects, or reliance on multiple independent systems, resulting in complex equipment structures, high costs, and broken data links.

[0004] In this process, because the existing equipment's monitoring cameras and optical paths are not designed for high-precision metrology, their imaging suffers from non-negligible and unstable distortion. Furthermore, the lack of a high-precision calibration target that is consistent with the printing reference and can be measured in situ makes it impossible to establish a reliable closed-loop calibration within the equipment. This forces the industry to commonly adopt an offline calibration method that involves removing a dedicated calibration board from the equipment and using an external high-precision imager for measurement. This method is not only inefficient but also introduces secondary errors during disassembly and handling, making it difficult to guarantee consistent accuracy during long-term stable operation. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing an automatic calibration and printing monitoring device for laser selective melting forming equipment, comprising: Molding chamber; A forming cylinder is disposed in the forming chamber, and a scraper frame is provided above the forming cylinder for mounting a powder spreading scraper; A substrate is connected to and driven by the molding cylinder, and the scraper spreads powder layer by layer onto the surface of the substrate by descending layer by layer. A substrate leveling component includes a substrate monitoring unit and a substrate posture adjustment unit. The substrate monitoring unit includes a first laser displacement sensor and a second laser displacement sensor mounted on a scraper holder. The substrate posture adjustment unit is connected to the bottom of the substrate and is used to adjust the posture of the substrate. A dual laser galvanometer system includes a first laser galvanometer unit acting on a first region of the substrate surface and a second laser galvanometer unit acting on a second region of the substrate surface. The first laser galvanometer unit and the second laser galvanometer unit are used to sinter metal powder of a target powder layer above the substrate. The monitoring component includes a CCD camera and a lens switching mechanism. The field of view of the CCD camera includes the entire substrate area, and the lens switching mechanism is used to switch between a high-transmittance lens and a laser protection lens in the field of view of the CCD camera. The controller is electrically connected to the substrate leveling component, the dual laser galvanometer system, and the monitoring component. The controller is configured to execute an in-situ automatic calibration process, which includes: Substrate leveling steps: Drive the scraper holder to move, so that the first laser displacement sensor and the second laser displacement sensor measure the distance to the substrate surface, and control the substrate posture adjustment unit to adjust the substrate to be horizontal; Galvanometer calibration step: After the substrate leveling step, the dual laser galvanometer system is controlled to directly print the calibration pattern on the leveled substrate surface, and the lens switching mechanism is controlled to make the high-transmittance lens enter the optical path, and the calibration pattern is captured by the CCD camera. The galvanometer calibration step includes: Single galvanometer precision calibration: Control the first laser galvanometer unit to print a first mark pattern at multiple first predetermined positions in the first region, and control the second laser galvanometer unit to print a second mark pattern at multiple first predetermined positions in the second region; Stitching accuracy calibration: Control the first laser galvanometer unit and the second laser galvanometer unit to print stitching calibration patterns at multiple second predetermined positions in the overlapping and intersecting area of ​​the first region and the second region; The controller is also configured to: analyze the images of the first marker pattern, the second marker pattern, and the stitching calibration pattern captured by the CCD camera, calculate the scanning position error of the first laser galvanometer unit and the second laser galvanometer unit and the stitching error of the two in the intersection area, and generate corresponding calibration parameters to update the galvanometer control system. The controller is also configured to execute a printing monitoring process: during the printing process in which the dual laser galvanometer system emits laser light, the controller controls the lens switching mechanism to switch the laser protective lens into the field of view optical path of the CCD camera for process monitoring; during the non-laser emission phase, the controller controls the lens switching mechanism to switch the high-transmittance lens into the optical path for image acquisition.

[0006] Preferably, the controller is configured in the galvanometer calibration step to: After completing the single galvanometer accuracy calibration, determine whether the scanning position error is less than a first preset threshold. If so, the calibration parameters are generated based on the calculated error model, and the printing of the graphic at the first predetermined position that was not printed is skipped.

[0007] Preferably, the plurality of first predetermined positions are distributed in a rectangular array within the first region and the second region; the plurality of second predetermined positions are distributed in a rectangular array within the intersection region.

[0008] Preferably, in the substrate leveling step, the drive scraper frame moves above the substrate, causing the first laser displacement sensor and the second laser displacement sensor to form three measuring points on the surface of the substrate. The substrate attitude adjustment unit includes a first electric lifting column, a second electric lifting column, and a third electric lifting column. The first electric lifting column, the second electric lifting column, and the third electric lifting column are arranged in an isosceles right triangle and are respectively connected to the three corners of the bottom surface of the substrate. The three measuring points correspond to the positions of the first electric lifting column, the second electric lifting column, and the third electric lifting column, respectively. The attitude of the substrate is adjusted by using the first electric lifting column, the second electric lifting column, and the third electric lifting column so that the data measured by the three measuring points are at preset values.

[0009] Preferably, the substrate leveling component further includes sensor calibration plates arranged on both sides of the substrate, and the controller is further configured to: Before the galvanometer calibration step begins, the first laser displacement sensor and the second laser displacement sensor are controlled to move above the sensor calibration plate to perform a reference calibration of the sensor's own height.

[0010] Preferably, the lens switching mechanism includes a linear drive structure, the laser protective lens is connected to the linear drive structure, the linear drive structure is used to drive the laser protective lens to enter or exit the field of view of the CCD camera, and the high-transmittance lens is connected to the mounting base of the CCD camera and held in the field of view of the CCD camera.

[0011] Preferably, the high-transmittance lens is quartz glass with a transmittance of ≥95%, and the laser protective lens is OD6 grade laser protective glass for a wavelength of 1064nm.

[0012] The second aspect of this invention proposes a technical solution: an automatic calibration and printing monitoring method for a laser selective melting forming equipment, using the aforementioned automatic calibration and printing monitoring device for a laser selective melting forming equipment, comprising the following steps: Automatic substrate leveling step: In the molding chamber, the substrate surface is scanned using a laser displacement sensor installed on the scraper holder, and the substrate is leveled by the substrate posture adjustment unit; In-situ optical path calibration step: After the automatic leveling step of the substrate, the following operations are performed in the molding chamber without removing the substrate: The dual-laser galvanometer system is controlled to print an array of calibration patterns on the surface of the substrate. The control and monitoring components cut the high-transmittance lens into the optical path of the CCD camera and capture the calibration pattern; Analyze the image, calculate the galvanometer scanning error and laser stitching error, and automatically update the calibration parameters; Printing process monitoring steps: After toner application, control the high-transmittance lens to enter the optical path for toner application quality inspection; during laser melting, control the laser protective lens to enter the optical path for real-time monitoring; after printing is completed, control the high-transmittance lens to enter the optical path for finished product surface inspection.

[0013] Preferably, the in-situ optical path calibration step includes an adaptive calibration sub-step: The dual-laser galvanometer system is controlled to print and analyze the first batch of calibration patterns at all predetermined first positions. If the analysis results show that the error is lower than the preset tolerance, the subsequent graphic printing at the first predetermined position will be terminated, and calibration parameters will be generated directly based on the existing data.

[0014] Preferably, the calibration pattern printing at the first predetermined position includes multiple batches, each batch having a first mark pattern printed by a first laser galvanometer unit and a second mark pattern printed by a second laser galvanometer unit, wherein the first mark pattern and the second mark pattern are concentric circles with different diameters.

[0015] Compared with the prior art, the advantages of the present invention are as follows: In this application, a stable and reliable geometric reference plane is established for subsequent galvanometer calibration through high-precision automatic leveling. The galvanometer and splicing calibration is performed on the flat substrate as an in-situ target, and the optical path error is corrected directly on the production reference in a closed loop. The accuracy and efficiency far exceed those of traditional offline methods. At the same time, this process relies on the precise visual feedback of the same integrated camera in high-transmittance mode. The precise optical path after calibration, combined with the adaptive switching monitoring system, can ensure that the images of the entire process from powder spreading and melting to finished product can be acquired and judged with high consistency in the same coordinate system.

[0016] This invention reconstructs the workflow of laser selective melting forming equipment from preparation to production, integrating the traditionally fragmented and manual processes into a fully automated, closed-loop, and continuous intelligent system. This not only improves the efficiency and yield of a single operation, but also lays the foundation for large-scale, unmanned production of metal additive manufacturing. Attached Figure Description

[0017] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the automatic calibration and printing monitoring device for laser selective melting forming equipment as shown in an embodiment of the present invention; Figure 2 This is a schematic diagram of the first round of calibration pattern printing performed at a first predetermined position in the cross region of the substrate surface, as shown in an embodiment of the present invention. Figure 3 This is a schematic diagram of the second round of calibration pattern printing performed at a first predetermined position in the cross region of the substrate surface, as shown in an embodiment of the present invention. Figure 4 This is a schematic diagram of splicing calibration pattern printing at a second predetermined position in the cross region of the substrate surface shown in an embodiment of the present invention; Figure 5 This is a schematic diagram of the lens switching mechanism shown in an embodiment of the present invention. Detailed Implementation

[0018] To better understand the technical content of this invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0019] {Example 1} Combination Figure 1 As shown, the first aspect of the present invention proposes a technical solution: an automatic calibration and printing monitoring device for a laser selective melting forming equipment, comprising a forming chamber 100, a forming cylinder 10, a substrate 20, a substrate leveling component 30, a dual laser galvanometer system 40, a monitoring component 50, and a controller.

[0020] The forming chamber 100 is a closed chamber equipped with an inert gas circulation and purification system, which can provide a controllable atmosphere, relatively stable temperature and safe closed processing environment for the laser melting and solidification of metal powder, prevent the metal from oxidizing at high temperature and accommodate the powder spreading and laser processing.

[0021] Furthermore, the molding cylinder 10 is disposed within the molding chamber 100, and a scraper holder 11 is provided above the molding cylinder 10 for mounting the powder spreading scraper. The substrate 20 is connected to the molding cylinder 10 and can be driven by the molding cylinder 10 to spread powder layer by layer onto the surface of the substrate 20 by descending layer by layer.

[0022] The scraper holder 11 is installed on the side wall of the molding chamber 100 and is driven by a linear drive structure to move along the length of the molding cylinder 10. It is used to cooperate with the scraper to complete powder spreading and to cooperate with the sensor to complete substrate calibration.

[0023] The substrate leveling component 30 also includes sensor calibration plates 33 arranged on both sides of the substrate 20.

[0024] Specifically, the sensor calibration plate 33 is a flat plate structure 331, which has a calibration plane.

[0025] Furthermore, the substrate leveling component 30 includes a substrate monitoring unit and a substrate posture adjustment unit 34. The substrate monitoring unit includes a first laser displacement sensor 31 and a second laser displacement sensor 32 mounted on the scraper holder 11. The substrate posture adjustment unit 34 is connected to the bottom of the substrate 20 and is used to adjust the posture of the substrate 20.

[0026] Specifically, the first laser displacement sensor 31 and the second laser displacement sensor 32 are both connected to the scraper holder 11 through an adjustable axial spacing adjustment mechanism. When the scraper holder 11 moves above the sensor calibration plate 33, the first laser displacement sensor 31 and the second laser displacement sensor 32 respectively detect the distance from the calibration plane of the flat plate structure 331, and correct the initial position of the two sensors according to this distance.

[0027] Optionally, both the first laser displacement sensor 31 and the second laser displacement sensor 32 are KEYENCE LK-G80 type sensors with a measurement accuracy of ±0.001mm.

[0028] Furthermore, the dual laser galvanometer system 40 includes a first laser galvanometer unit 41 acting on a first region on the surface of the substrate 20, and a second laser galvanometer unit 42 acting on a second region on the surface of the substrate 20, wherein the first laser galvanometer unit 41 and the second laser galvanometer unit 42 are used to sinter the metal powder of the target powder layer above the substrate 20.

[0029] Specifically, the first laser galvanometer unit 41 and the second laser galvanometer unit 42 have the same structure, both including a laser, a beam expander, X-axis and Y-axis scanning galvanometers driven by two high-speed servo motors, and a focusing lens.

[0030] For each laser galvanometer unit, the laser beam emitted from the laser is expanded and collimated before entering the X and Y galvanometers. By controlling the reflection angles of the two galvanometer mirrors, the deflection position of the laser beam on the focal plane of the substrate 20 surface can be precisely controlled, achieving high-speed scanning. Due to factors such as mechanical assembly errors of the galvanometers, motor nonlinearity, inherent optical distortions of the lenses (such as pincushion / barrel distortion), and thermal effects, there is a nonlinear error between the theoretical coordinates commanded by the galvanometer system and the actual spot position.

[0031] For dual-laser systems, the superposition of errors from the two independent galvanometer systems can also cause scanning mismatch (stitching error) within the overlapping intersection region 202. Therefore, high-precision calibration is necessary to ensure the dimensional accuracy of the formed parts and the quality of the stitching area.

[0032] Furthermore, in order to achieve optical path calibration of the dual laser galvanometer system 40 and monitoring of the laser selective melting process, a monitoring component 50 is also provided. The monitoring component 50 includes a CCD camera 51 and a lens switching mechanism 52. The field of view of the CCD camera 51 includes the entire substrate 20 area.

[0033] In an optional embodiment, the CCD camera 51 is a Basler acA2500-14uc camera.

[0034] In this application, the CCD camera 51 serves as a precision measurement tool for optical path calibration, used to capture calibration patterns on the surface of the substrate 20. Subpixel-level center coordinates of the light spot are obtained through image analysis, providing data for calculating the galvanometer error. Simultaneously, the CCD camera 51 also serves as a visual sensor for full-process printing monitoring, used to observe powder uniformity, monitor the melt pool status in real time, and detect the surface quality of the finished product.

[0035] Furthermore, the lens switching structure 52 is used to switch between a high-transmittance lens 521 and a laser protection lens 522 in the field of view of the CCD camera 51.

[0036] When the device is in a non-laser emission state, such as during optical path calibration, taking pictures after toner application, or quality inspection after printing, the controller controls the lens switching mechanism 52 to move the laser protection lens 522 out of the optical path, so that the CCD camera 51 can image through the fixed high-transmittance lens 521 to obtain the highest image clarity and transmittance. When the device is in the laser emission printing process, the controller immediately drives the lens switching mechanism 52 to switch the laser protection lens 522 into the optical path. This lens can effectively filter out or attenuate 1064nm laser radiation, prevent strong laser from damaging the camera sensor, and ensure that clear molten pool monitoring images can still be collected in the laser environment.

[0037] In an optional embodiment, the high-transmittance lens 521 is quartz glass with a transmittance of ≥95%, and the laser protective lens 522 is OD6 grade laser protective glass for a wavelength of 1064nm.

[0038] Combination Figure 5 As shown, the lens switching mechanism 52 can be selected as a linear drive structure 523. The laser protective lens 522 is connected to the linear drive structure 523. The linear drive structure 523 is used to drive the laser protective lens 522 to enter or exit the field of view of the CCD camera 51.

[0039] Specifically, the high-transmittance lens 521 is connected to the mounting base of the CCD camera 51 and remains in the field of view of the CCD camera 51.

[0040] Furthermore, the controller is electrically connected to the substrate leveling component 30, the dual laser galvanometer system 40, and the monitoring component 50, and the controller is configured to execute an in-situ automatic calibration process, which includes: Substrate leveling steps: Drive the scraper holder 11 to move, so that the first laser displacement sensor 31 and the second laser displacement sensor 32 measure the distance to the surface of the substrate 20, and control the substrate posture adjustment unit 34 to adjust the substrate 20 to be horizontal. Galvanometer calibration step: After the substrate leveling step, the dual laser galvanometer system 40 is controlled to directly print the calibration pattern on the leveled substrate 20 surface, and the lens switching mechanism 52 is controlled to make the high-transmittance lens 521 enter the optical path, and the calibration pattern is captured by the CCD camera 51.

[0041] Compared to the offline calibration mode of existing technologies that involves substrate disassembly, external inspection, and substrate reassembly, this method directly uses the leveled production substrate as the calibration target surface and utilizes the same CCD camera integrated within the device for image acquisition and analysis. This forms a closed loop of measurement, calculation, and compensation within the device, which not only improves calibration efficiency but also eliminates the reference transfer step, ensuring that calibration accuracy is no longer affected by external operations and can be maintained stably at the micrometer level for a long time. This solves the technical contradiction between the low efficiency and the difficulty in consistently guaranteeing accuracy in traditional methods.

[0042] As mentioned above, based on the in-situ automatic calibration process, the workflow of the laser selective melting forming equipment from preparation to production is reconstructed, integrating the three discrete links of traditional substrate calibration, galvanometer calibration and printing process that are mutually isolated and dependent on manual labor into a fully automatic, closed-loop and continuous intelligent system.

[0043] In an optional embodiment, combined with Figures 2 to 4 As shown, the calibration pattern consists of multiple concentric circles of different diameters, which are alternately printed at the same position by the first laser galvanometer unit 41 and the second laser galvanometer unit 42, and a maximum of six concentric circles can be printed.

[0044] In an optional embodiment, combined with Figures 2 to 4 As shown, multiple first predetermined positions 21 are distributed in a rectangular array within the first and second regions; multiple second predetermined positions 22 are distributed in a rectangular array within the intersection region 202.

[0045] Specifically, in combination Figure 2As shown, the first region excluding the intersection region 202 is the first laser region 201, which cannot be covered by the second laser galvanometer unit 42. The second region excluding the intersection region 202 is the second laser region 203, which cannot be covered by the first laser galvanometer unit 41.

[0046] As mentioned above, calibration can be performed on the entire substrate surface through a matrix arrangement of calibration positions, thereby achieving precise global compensation of the galvanometer scanning path.

[0047] The galvanometer calibration steps include: Single galvanometer precision calibration: Control the first laser galvanometer unit 41 to print the first mark pattern at multiple first predetermined positions 21 in the first area, and control the second laser galvanometer unit 42 to print the second mark pattern at multiple first predetermined positions 21 in the second area; Stitching accuracy calibration: Control the first laser galvanometer unit 41 and the second laser galvanometer unit 42 to print stitching calibration patterns at multiple second predetermined positions 22 within the overlapping area 202 of the first region and the second region.

[0048] Furthermore, the controller is also configured to: analyze the images of the first marker pattern, the second marker pattern, and the stitching calibration pattern captured by the CCD camera 51, calculate the scanning position error of the first laser galvanometer unit 41 and the second laser galvanometer unit 42, as well as the stitching error of the two in the intersection area 202, and generate corresponding calibration parameters to update the galvanometer control system.

[0049] Specifically, by analyzing the shapes of the first and second marker graphics at the same predetermined position, the actual positional deviation of the printed graphics can be identified, so as to fit a high-precision full-field error mathematical model and calibrate the galvanometer scanning path. Since it is not necessary to disassemble the substrate, the marker images printed in multiple rounds at the same position can be referenced to each other, which is conducive to verifying whether the calibration results are accurate. Substrate leveling

[0050] Optionally, the controller is also configured to: before the galvanometer calibration step begins, control the first laser displacement sensor 31 and the second laser displacement sensor 32 to move above the sensor calibration plate 33 to perform a reference calibration of the sensor's own height.

[0051] Optionally, in the substrate leveling step, the drive scraper holder 11 is moved above the substrate 20, so that the first laser displacement sensor 31 and the second laser displacement sensor 32 form three measuring points on the surface of the substrate 20.

[0052] Furthermore, the substrate attitude adjustment unit 34 includes a first electric lifting column 341, a second electric lifting column 342, and a third electric lifting column 343. The first electric lifting column 341, the second electric lifting column 342, and the third electric lifting column 343 are arranged in an isosceles right triangle and are respectively connected to the three corners of the bottom surface of the substrate 20. The three measuring points correspond to the positions of the first electric lifting column 341, the second electric lifting column 342, and the third electric lifting column 343, respectively.

[0053] Thus, the attitude of the base plate 20 is adjusted by using the first electric lifting column 341, the second electric lifting column 342 and the third electric lifting column 343 until the data measured by the three ranging points are at the preset value.

[0054] During the specific leveling process, before leveling begins, the controller first drives the scraper holder 11 to move, so that the first laser displacement sensor 31 and the second laser displacement sensor 32 are aligned with the sensor calibration plates 33 on both sides in sequence to perform their own height reference calibration and eliminate sensor zero-point errors. If errors exist, the position of the first laser displacement sensor 31 or the second laser displacement sensor 32 is adjusted until the errors are eliminated.

[0055] Subsequently, the drive scraper holder 11 carries the sensor and moves above the substrate 20 to measure the height of three measuring points corresponding to the three electric lifting columns 341, 342 and 343.

[0056] Compared to existing technologies that rely on manual leveling using tools like feeler gauges and dial indicators for large substrates, this application utilizes a controller to calculate the height deviation at each of three measurement points and drive the corresponding electric lifting column to compensate for the height difference until the height difference reaches a preset accuracy (e.g., within ±0.02mm). This achieves fully automated, high-precision substrate leveling, reducing the time-consuming manual leveling process to just a few minutes. This not only improves efficiency but, more importantly, provides a stable and high-precision geometric reference plane for subsequent optical path calibration, ensuring the calibration and printing accuracy of the entire system. Galvanometer calibration

[0057] In the specific galvanometer calibration process: after obtaining the horizontal substrate, the controller executes the calibration procedure. First, single galvanometer accuracy calibration is performed: the first laser galvanometer unit 41 is controlled to print first marking patterns (innermost circles, such as...) at multiple first predetermined positions 21 within its responsible first area. Figure 2 (The red circle in the image), while simultaneously controlling the second laser galvanometer unit 42 to print the second marking pattern (the circle in the outer layer, such as the red circle in the image) at the first predetermined position 21 corresponding to its second region. Figure 2(The blue circle in the image). The CCD camera 51 captures these images through the high-transmittance lens 521.

[0058] Furthermore, in the galvanometer calibration step, if the controller determines whether the scanning position error is less than a first preset threshold after the first single galvanometer accuracy calibration is completed, and if so, it generates calibration parameters based on the calculated error model and skips printing the unprinted portion of the first predetermined position 21. If it is greater than the first preset threshold, then... Figure 3 As shown, a second marking pattern printing is performed. The first laser galvanometer unit 41 prints the first marking pattern (the outermost red circle) at multiple first predetermined positions 21 in the first area it is responsible for. At the same time, it controls the second laser galvanometer unit 42 to print the second marking pattern (the outermost blue circle) at the corresponding first predetermined position 21 in the second area. After the second single galvanometer accuracy calibration is completed, the controller determines whether the scanning position error is less than the first preset threshold. If so, it generates calibration parameters based on the calculated error model and skips the printing of the remaining unprinted first predetermined positions 21.

[0059] The controller identifies the center coordinates of each graphic using an image analysis algorithm, compares them with the theoretical coordinates, and calculates the nonlinear error model of each galvanometer.

[0060] Subsequently, splicing accuracy calibration is performed: the two galvanometer units are controlled to be at multiple second predetermined positions 22 within the intersection region 202, and specific splicing calibration patterns (such as...) are printed individually or sequentially. Figure 4 As shown, concentric circles are printed sequentially by two lasers. By analyzing the deviation between the centers of the printed graphics from the two lasers, the splicing error is calculated and compensated for.

[0061] In the galvanometer calibration process described above, if the error is found to be less than the threshold in the first batch of calibrations, the controller can intelligently decide to skip printing subsequent calibration patterns, thereby improving calibration efficiency.

[0062] It should be understood that traditional calibration processes are offline, and the calibration board is not a substrate. When calibrating the galvanometer, all preset calibration points are printed at once, and then removed for measurement, resulting in wasted time. This application, however, can analyze the image of the first batch of calibration patterns in real time and determine whether the error is below a preset threshold. If the requirement is met, it is inferred that the current galvanometer error model is sufficiently accurate, thus skipping the printing and measurement of remaining redundant calibration points and directly generating the final calibration parameters. Therefore, calibration efficiency can be improved, and full calibration can still be performed when necessary, i.e., printing all patterns, to further ensure calibration accuracy.

[0063] Furthermore, a stable and reliable geometric reference plane is established for subsequent galvanometer calibration through high-precision automatic leveling. The galvanometer and splicing calibration is performed on the flat substrate as an in-situ target, and the optical path error is corrected directly on the production reference in a closed loop. The accuracy and efficiency far exceed those of traditional offline methods. At the same time, this process relies on the precise visual feedback of the same integrated camera in high-transmittance mode. The precise optical path after calibration, combined with the adaptive switching monitoring system, can ensure that the images of the entire process from powder spreading and melting to finished product can be acquired and judged with high consistency in the same coordinate system. Print monitoring

[0064] Furthermore, the controller is also configured to execute the printing monitoring process: during the printing process in which the dual laser galvanometer system 40 emits lasers, the control lens switching mechanism 52 switches the laser protective lens 522 into the field of view optical path of the CCD camera 51 for process monitoring; during the non-laser emission stage, the control lens switching mechanism 52 switches the high-transmittance lens 521 into the optical path for image acquisition.

[0065] After entering the formal printing cycle, after each toner application, the controller switches to the high-transmittance lens 521, and the CCD camera 51 captures an image of the toner layer. The toner quality is judged by analyzing the grayscale uniformity of the image. When the laser scanning starts, the lens instantly switches to the laser protection lens 522. The CCD camera 51 can safely monitor the shape, brightness and stability of the molten pool in real time. After one layer is printed, the laser is paused, and the lens can be switched again for rapid imaging of the surface of that layer.

[0066] This process is repeated until the part is complete.

[0067] The integrated monitoring solution described above enables full-process visualization and quality traceability from powder spreading to forming, and uses only one camera to meet the conflicting requirements of high-precision measurement and strong light protection, reducing system cost and complexity.

[0068] {Example 2} The second aspect of this invention proposes a technical solution: an automatic calibration and printing monitoring method for a laser selective melting forming equipment, using the aforementioned automatic calibration and printing monitoring device for a laser selective melting forming equipment, comprising the following steps: Automatic leveling step of substrate: In the molding chamber 100, the surface of substrate 20 is scanned by a laser displacement sensor installed on the scraper holder 11, and substrate 20 is leveled by substrate posture adjustment unit 34. In-situ optical path calibration step: After the substrate automatic leveling step, within the molding chamber 100 and without removing the substrate 20, perform the following operations: The dual laser galvanometer system 40 is controlled to print an array of calibration patterns on the surface of the substrate 20. The control and monitoring unit 50 cuts the high-transmittance lens 521 into the optical path of the CCD camera 51 and captures a calibration image; Analyze the image, calculate the galvanometer scanning error and laser stitching error, and automatically update the calibration parameters; Printing process monitoring steps: After toner application, control the high-transmittance lens 521 to enter the optical path for toner application quality detection; during laser melting, control the laser protective lens 522 to enter the optical path for real-time monitoring; after printing, control the high-transmittance lens 521 to enter the optical path for finished product surface inspection.

[0069] Furthermore, the in-situ optical path calibration step includes an adaptive calibration sub-step: The dual laser galvanometer system 40 is controlled to print and analyze the first batch of calibration patterns at all first predetermined positions 21. If the analysis results show that the error is lower than the preset tolerance, the subsequent graphic printing at the first predetermined position 21 will be terminated, and calibration parameters will be generated directly based on the existing data.

[0070] In a preferred embodiment, the calibration pattern printing at the first predetermined position 21 includes multiple batches, each batch having a first mark pattern printed by the first laser galvanometer unit 41 and a second mark pattern printed by the second laser galvanometer unit 42, wherein the first mark pattern and the second mark pattern are concentric circles with different diameters.

[0071] Based on the apparatus of Embodiment 1, taking the printing of 316L stainless steel parts as an example, the usage method is as follows: S1: The device is powered on and started. The controller automatically detects the status of each module. The laser displacement sensor is preheated for 5 minutes. The laser protective lens 522 cuts out the optical path of the CCD camera 31. The high-transmittance lens 521 is located directly below the optical path of the CCD camera 31. S2: Fix the 316L stainless steel base plate to the base plate connecting plate above the electric lifting column. The two laser displacement sensors first move to the sensor calibration plates 33 on both sides of the forming cylinder through the powder spreading shaft. The distance data is required to meet 50±0.01mm. If it does not meet the requirement, readjust the assembly height of the laser displacement sensor 1 until it meets the requirement. Then, collect the initial distance data of the three detection points above the three electric lifting columns, which are 50.123mm, 50.345mm and 50.089mm respectively. The main control unit calculates that the adjustment amount required for each point is -0.103mm, -0.325mm and -0.069mm. After driving the three electric lifting columns to complete the adjustment, the secondary detection data are 50.03mm, 50.04mm and 50.04mm. The leveling accuracy meets the tolerance requirement of 0~+0.04mm. S3: The dual-laser galvanometer system 40 prints calibration patterns (galvanometer calibration standard circles) at first predetermined positions 21 on the surface of the substrate 20. Each first predetermined position 21 can print up to six concentric circles, with adjacent circles printed by different laser galvanometer units. First, the first laser galvanometer unit 41 prints the innermost circle, then the second laser galvanometer unit 42 prints the next innermost circle. Then, the CCD camera 51 captures images of the printed circular light spots. The main control unit identifies the deviations between the center coordinates of the light spots and the given theoretical coordinates as (+0.01 mm, -0.02 mm) and (-0.01 mm, +0.01 mm), respectively. (mm), meeting the requirement that the deviation after galvanometer calibration is better than ±0.02mm, the galvanometer calibration is completed, and the remaining 4 sets of concentric circles do not need to be printed again; print the splicing calibration pattern (two concentric circles) at each of the second predetermined positions 22 in the intersection area 202 of the dual laser splicing; firstly, the first laser galvanometer unit 41 prints the inner circle, then the second laser galvanometer unit 42 prints the outer circle, and then the CCD camera 51 captures the image of the printed circle spot, automatically generates calibration parameters and updates them to the galvanometer control system, and the deviation after calibration is ≤±0.05mm; S4: The powder spreading mechanism spreads 316L stainless steel powder to a thickness of 0.04mm. The CCD camera 51 captures the powder spreading image, and the main control unit analyzes the grayscale value to determine that the powder spreading uniformity is 98.5%, which meets the printing requirements. S5: Start the printing program. The linear drive structure 523 completes the switching of the laser protective lens 522 into the area directly below the CCD camera 51 within 100ms. The CCD camera 51 captures the printing process in real time. S6: After printing is completed, the laser stops, and the linear drive structure 523 automatically cuts the laser protective lens 522 to a position away from the CCD camera 51. The CCD camera 51 then captures an image of the finished product surface. S7: Repeat S4-S6 until the entire part is printed, remove the printed product, and reset the equipment.

[0072] The aforementioned automatic calibration and print monitoring methods provide a unique and stable physical reference for all subsequent steps through high-precision automatic leveling. In-situ calibration based on the same reference plane utilizes this reference, along with integrated visual feedback, to complete the calibration work that traditionally takes hours, within minutes. Single-camera dual-path switching monitoring relies on the precise coordinate system established in the preceding steps to achieve seamless and highly consistent observation of the entire production process. This process integration reduces the time from standby preparation to stable printing from several hours to tens of minutes, achieving fully automated printing operations.

[0073] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. An automatic calibration and printing monitoring device for laser selective melting forming equipment, characterized in that, include: Molding chamber (100); A forming cylinder (10) is disposed in the forming chamber (100), and a scraper holder (11) is provided above the forming cylinder (10). The scraper holder (11) is used to install a powder spreading scraper. The substrate (20) is connected to the molding cylinder (10) and can be driven by the molding cylinder (10) to spread powder layer by layer onto the surface of the substrate (20) by the scraper as it descends layer by layer. The substrate leveling component (30) includes a substrate monitoring unit and a substrate posture adjustment unit (34). The substrate monitoring unit includes a first laser displacement sensor (31) and a second laser displacement sensor (32) mounted on the scraper holder (11). The substrate posture adjustment unit (34) is connected to the bottom of the substrate (20) and is used to adjust the posture of the substrate (20). The dual laser galvanometer system (40) includes a first laser galvanometer unit (41) acting on a first region on the surface of the substrate (20) and a second laser galvanometer unit (42) acting on a second region on the surface of the substrate (20). The first laser galvanometer unit (41) and the second laser galvanometer unit (42) are used to sinter the metal powder of the target powder layer above the substrate (20). The monitoring component (50) includes a CCD camera (51) and a lens switching mechanism (52). The field of view of the CCD camera (51) includes the entire substrate (20) area. The lens switching mechanism (52) is used to switch between a high-transmittance lens (521) or a laser protection lens (522) in the field of view of the CCD camera (51). The controller is electrically connected to the substrate leveling component (30), the dual laser galvanometer system (40), and the monitoring component (50); The controller is configured to execute an in-situ automatic calibration process, which includes: Substrate leveling steps: Drive the scraper holder (11) to move, so that the first laser displacement sensor (31) and the second laser displacement sensor (32) measure the distance on the surface of the substrate (20), and control the substrate posture adjustment unit (34) to adjust the substrate (20) to be horizontal; Galvanometer calibration step: After the substrate leveling step, the dual laser galvanometer system (40) is controlled to directly print the calibration pattern on the leveled substrate (20) surface, and the lens switching mechanism (52) is controlled to make the high-transmittance lens (521) cut into the optical path, and the calibration pattern is captured by the CCD camera (51). The galvanometer calibration step includes: Single galvanometer precision calibration: Control the first laser galvanometer unit (41) to print a first mark pattern at multiple first predetermined positions (21) in the first region, and control the second laser galvanometer unit (42) to print a second mark pattern at multiple first predetermined positions (21) in the second region; Splicing accuracy calibration: Control the first laser galvanometer unit (41) and the second laser galvanometer unit (42) to print splicing calibration patterns at multiple second predetermined positions (22) within the overlapping and intersecting area (202) of the first region and the second region; The controller is also configured to: analyze the images of the first marker pattern, the second marker pattern and the stitching calibration pattern captured by the CCD camera (51), calculate the scanning position error of the first laser galvanometer unit (41) and the second laser galvanometer unit (42) and the stitching error of the two in the intersection area (202) respectively, and generate corresponding calibration parameters to update the galvanometer control system. The controller is also configured to execute a printing monitoring process: during the printing process in which the dual laser galvanometer system (40) emits lasers, the controller controls the lens switching mechanism (52) to switch the laser protective lens (522) into the field of view optical path of the CCD camera (51) for process monitoring; during the non-laser emission stage, the controller controls the lens switching mechanism (52) to switch the high-transmittance lens (521) into the optical path for image acquisition.

2. The automatic calibration and printing monitoring device for laser selective melting forming equipment according to claim 1, characterized in that, The controller is configured in the galvanometer calibration step as follows: After completing the single galvanometer accuracy calibration, determine whether the scanning position error is less than a first preset threshold. If so, the calibration parameters are generated based on the calculated error model, and the graphic printing of the first predetermined position (21) that was not printed is skipped.

3. The automatic calibration and printing monitoring device for laser selective melting forming equipment according to claim 1 or 2, characterized in that, Multiple first predetermined positions (21) are distributed in a rectangular array within the first region and the second region; multiple second predetermined positions (22) are distributed in a rectangular array within the intersection region (202).

4. The automatic calibration and printing monitoring device for laser selective melting forming equipment according to claim 1, characterized in that, In the substrate leveling step, the drive scraper holder (11) moves above the substrate (20), so that the first laser displacement sensor (31) and the second laser displacement sensor (32) form three measuring points on the surface of the substrate (20). The substrate attitude adjustment unit (34) includes a first electric lifting column (341), a second electric lifting column (342) and a third electric lifting column (343). The first electric lifting column (341), the second electric lifting column (342) and the third electric lifting column (343) are arranged in an isosceles right triangle and are respectively connected to the three corners of the bottom surface of the substrate (20). The three measuring points correspond to the positions of the first electric lifting column (341), the second electric lifting column (342) and the third electric lifting column (343). The attitude of the substrate (20) is adjusted by the first electric lifting column (341), the second electric lifting column (342) and the third electric lifting column (343) so that the data measured by the three measuring points are at the preset value.

5. The automatic calibration and printing monitoring device for laser selective melting forming equipment according to claim 1, characterized in that, The substrate leveling component (30) further includes sensor calibration plates (33) arranged on both sides of the substrate (20), and the controller is further configured to: Before the galvanometer calibration step begins, the first laser displacement sensor (31) and the second laser displacement sensor (32) are controlled to move above the sensor calibration plate (33) to perform a reference calibration of the sensor's own height.

6. The automatic calibration and printing monitoring device for laser selective melting forming equipment according to claim 1, characterized in that, The lens switching mechanism (52) includes a linear drive structure (523), the laser protective lens (522) is connected to the linear drive structure (23), the linear drive structure (523) is used to drive the laser protective lens (522) to enter or exit the field of view of the CCD camera (51), and the high-transmittance lens (521) is connected to the mounting base of the CCD camera (51) and held in the field of view of the CCD camera (51).

7. The automatic calibration and printing monitoring device for laser selective melting forming equipment according to claim 1, characterized in that, The high-transmittance lens (521) is quartz glass with a transmittance of ≥95%, and the laser protective lens (522) is OD6 grade laser protective glass for a wavelength of 1064nm.

8. An automatic calibration and printing monitoring method for a laser selective melting forming equipment, characterized in that, The automatic calibration and printing monitoring device for laser selective melting forming equipment according to any one of claims 1-7 includes the following steps: Automatic leveling step of substrate: In the molding chamber (100), the surface of the substrate (20) is scanned by a laser displacement sensor installed on the scraper holder (11), and the substrate (20) is leveled by the substrate posture adjustment unit (34). In-situ optical path calibration step: After the automatic leveling step of the substrate, within the molding chamber (100) and without removing the substrate (20), the following operations are performed: The dual laser galvanometer system (40) is controlled to print an array of calibration patterns on the surface of the substrate (20); The control and monitoring unit (50) cuts the high-transmittance lens (521) into the optical path of the CCD camera (51) and captures the calibration pattern; Analyze the image, calculate the galvanometer scanning error and laser stitching error, and automatically update the calibration parameters; Printing process monitoring steps: After powder spreading, control the high-transmittance lens (521) to enter the optical path for powder spreading quality detection; during laser melting, control the laser protective lens (522) to enter the optical path for real-time monitoring; after printing is completed, control the high-transmittance lens (521) to enter the optical path for finished product surface detection.

9. The automatic calibration and printing monitoring method for laser selective melting forming equipment according to claim 8, characterized in that, The in-situ optical path calibration step includes an adaptive calibration sub-step: The dual laser galvanometer system (40) is controlled to print and analyze the first batch of calibration patterns at all first predetermined positions (21); If the analysis results show that the error is lower than the preset tolerance, the subsequent graphic printing at the first predetermined position (21) will be terminated, and calibration parameters will be generated directly based on the existing data.

10. The automatic calibration and printing monitoring method for laser selective melting forming equipment according to claim 9, characterized in that, The calibration pattern printing performed at the first predetermined position (21) includes multiple batches, each batch having a first mark pattern printed by a first laser galvanometer unit (41) and a second mark pattern printed by a second laser galvanometer unit (42), wherein the first mark pattern and the second mark pattern are concentric circles with different diameters.

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