A 3D printing method, equipment and laser position calibration method and device

Abstract

A laser position calibration method for 3D printing equipment includes the following steps: turning off the illumination light source within a working chamber; controlling at least one laser system to emit a laser according to a preset program in a working area where powder has been laid, wherein the laser energy density of the laser is lower than the unit density melting heat of the powder and can interact with the powder; using a detector to record the trajectory of the laser acting on the powder to form an image to be processed; obtaining several features of the image to be processed, and calibrating the laser system by analyzing the several features. The laser position calibration method of the present invention is performed directly within the working chamber, i.e., there is no need to open the sealed door of the working chamber and no additional calibration device is required; furthermore, there are few additional steps, a simple calibration method, high work efficiency, and high calibration accuracy.

Description

Technical Field

[0001] The present application relates to the field of additive manufacturing technology, and in particular to a 3D printing method, equipment, and a laser position calibration method and device thereof. Background Art

[0002] Additive manufacturing is an advanced manufacturing technology characterized by digital manufacturing, high flexibility and adaptability, direct CAD model-driven operation, rapid speed, and a wide variety of materials. Because it is not restricted by part shape complexity and does not require any tooling, it has a wide range of applications. Selective Laser Melting (SLM) is one of the most rapidly developing additive manufacturing technologies in recent years. Using powdered materials as raw materials, it uses a laser to scan the cross-section of a three-dimensional solid layer by layer to create prototypes. It is not restricted by part shape complexity and does not require any tooling, thus having a wide range of applications. The basic process of selective laser melting is: the powder feeding device delivers a certain amount of powder to the working platform surface, the powder spreading device spreads a layer of powder material on the bottom plate of the forming cylinder or the upper surface of the formed part, and the laser galvanometer system controls the laser to scan the solid part of the powder layer according to the cross-sectional contour of the layer with an approximately constant spot size and beam energy, so that the powder melts and bonds with the formed part below; when a layer of cross section is sintered, the working platform drops one layer of thickness, and the powder spreading device spreads a layer of uniform and dense powder on it, and scans and sinters a new layer of cross section. After several layers of scanning and superposition, the entire prototype manufacturing is completed.

[0003] Laser scanning accuracy calibration and multi-laser overlap issues are common problems faced by the industrial additive manufacturing field during its application process. Due to the nonlinear relationship between the deflection of the galvanometer angle and the coordinates of the printing plane, coupled with the manufacturing errors of the optical components themselves and the errors in the assembly process, galvanometer scanning accuracy calibration is necessary to ensure the molding accuracy. In addition, as the printing format expands, the number of lasers used in the same device is increasing. The print quality of areas where different lasers are printing together is affected by the relative positions of the different lasers. If there is a misalignment between different lasers, it will cause joint lines on the workpiece, resulting in defects in the workpiece, thereby affecting the mechanical properties of the workpiece.

[0004] Currently, the industry's galvanometer scanning accuracy calibration and multi-laser overlap calibration methods are generally offline. These methods primarily include the following: One method involves placing the printed media flat on a clean substrate after printing and sintering, keeping it in the focal plane. Laser beams are then used to print a scanning pattern at the overlap position on the media. The pattern's state determines the laser scanning accuracy and the position between the lasers. This pattern is then used to compensate for the galvanometer scanning accuracy and adjust the galvanometer rotation and deviation parameters to optimize scanning accuracy and overlap. This method's accuracy is easily affected by the placement and flatness of the printed media, resulting in inaccuracies in the printed pattern and adjustment adjustments. Another method, multi-laser overlap, uses a specific, actual overlapped part to be sintered. The resulting overlapped part's shape determines the relative position between the lasers and adjusts the galvanometer parameters. This method fully simulates actual working conditions, reducing the introduction of other errors. However, sintering actual overlapped parts is time-consuming (at least several hours), expensive, and requires highly experienced personnel to accurately determine the parameter adjustment direction, making it unsuitable for widespread use. Summary of the Invention

[0005] In order to solve the above-mentioned technical problems existing in the prior art, the present invention provides a 3D printing method, equipment and laser position calibration method and device thereof. The method is directly performed in the working chamber, that is, there is no need to open the sealed door of the working chamber, and no additional calibration devices are required; moreover, there are few additional steps, the calibration method is simple, the work efficiency is high, and the calibration accuracy is high.

[0006] To achieve the above object, the present invention provides a laser position calibration method for a 3D printing device, comprising the following steps:

[0007] Step S1, turning off the lighting source in the working chamber;

[0008] Step S2, controlling at least one laser system to emit laser light according to a preset program in a working area where the powder has been laid, wherein the laser light has a laser energy density lower than the unit density melting heat of the powder and can interact with the powder;

[0009] Step S3: using a detector to record the trajectory of the laser acting on the powder to form an image to be processed;

[0010] Step S4: Acquire several features of the image to be processed, and calibrate the laser system by analyzing the several features.

[0011] As a further preferred embodiment of the present invention, the image to be processed includes at least two intersecting line segments, the features include angle features and feature position coordinates; and the detector is a camera.

[0012] As a further preferred embodiment of the present invention, when there is only one laser system, the laser system emits laser light on the powder in the working area according to a preset program to interact with the powder; when there are two or more laser systems, two adjacent laser systems emit laser light on the powder in the splicing area according to a preset program to interact with the powder, and the trajectories of the two adjacent laser systems acting on the powder correspond one to one.

[0013] As a further preferred embodiment of the present invention, when there is only one laser system, the calibration of the laser system by analyzing several features in step S4 specifically includes:

[0014] Step S411: Calculate all angle feature values ​​and feature position coordinate values ​​in the image to be processed, and calculate their deviations from the corresponding theoretical values.

[0015] Step S412 : Calculate the average value of the deviations of all angle characteristic values ​​and the average value of the deviations of all characteristic position coordinate values, and compensate the angle and offset of the galvanometer unit of the laser system according to the average values.

[0016] As a further preferred embodiment of the present invention, when there are two or more laser systems, the calibration of the laser systems by analyzing several features in step S4 specifically includes:

[0017] Step S421: Calculate all angle eigenvalues ​​in the image to be processed, and calculate the deviations of all angle eigenvalues ​​from the corresponding theoretical values. The average of all deviations is the overall angle deviation, which is the camera deflection angle.

[0018] Step S422: Rotate and correct the image to be processed according to the camera deflection angle to obtain a corrected image; and calculate all angle feature values ​​and feature position coordinate values ​​of the corrected image;

[0019] Step S423: Select one laser system as a reference laser system, and use at least one angle characteristic value and characteristic position coordinate value corresponding to the reference laser system as a reference value. Based on the reference value, theoretical angle characteristic values ​​and theoretical characteristic position coordinate values ​​corresponding to all laser systems except the reference laser system are obtained in sequence according to the overlapping principle.

[0020] Step S424, calculate the deviations of the angle characteristic values ​​and characteristic position coordinate values ​​of all laser systems except the reference laser system in the corrected image relative to the corresponding theoretical angle characteristic values ​​and theoretical characteristic position coordinate values, calculate the average value of the deviations of all angle characteristic values ​​and the average value of the deviations of all characteristic position coordinate values ​​of each laser system, and compensate for the angle and offset of the galvanometer unit of the corresponding laser system according to the average value.

[0021] As a further preferred embodiment of the present invention, the step S4 further includes the following steps:

[0022] Step S5, controlling at least one laser system to emit laser light according to a preset program in a working area where the powder has been laid, wherein the laser light has a laser energy density lower than the unit density melting heat of the powder and can interact with the powder;

[0023] Step S6: Use a camera to record the trajectory of the laser acting on the powder to form an image to be processed, and use the camera deflection angle obtained in step S421 to rotationally correct the image to be processed, and obtain at least one angle characteristic value and characteristic position coordinate value of each laser system in the corrected image as an initial reference value.

[0024] The present invention also provides a laser position calibration device for a 3D printing device, comprising a memory and a processor, wherein the memory stores a computer program, and wherein the processor implements the steps of any of the above-mentioned methods for calibrating the laser position of a 3D printing device when executing the computer program.

[0025] The present invention further provides a 3D printing method, comprising the following steps:

[0026] After the workpiece to be printed reaches a first preset number of layers, the laser position calibration method of any one of the above-mentioned 3D printing devices is started to calibrate the laser system.

[0027] The present invention further provides a 3D printing method, comprising the following steps:

[0028] Step S101: After the workpiece to be printed reaches a first preset number of layers, the laser position calibration method of the 3D printing device described above is started to calibrate the laser system;

[0029] Step S102: After the calibration is completed, the illumination light source is turned on to continue printing the workpiece to be printed. After the workpiece to be printed reaches a second preset number of layers, the illumination light source in the working chamber is turned off.

[0030] Step S103: Control at least one laser system to emit laser light according to a preset program in a working area where the powder has been laid, wherein the laser light has a laser energy density lower than the unit density melting heat of the powder and can interact with the powder;

[0031] Step S104: Using a detector to record the trajectory of the laser acting on the powder to form an image to be processed, and using the camera deflection angle obtained in step S421 to perform rotation correction on the image to be processed, respectively obtaining the angle characteristic value and characteristic position coordinate value of each laser system in the corrected image;

[0032] Step S105: Calculate the deviations of the angular characteristic values ​​and characteristic position coordinate values ​​of all laser systems relative to the corresponding initial reference values ​​in step S6, and calculate the average value of the deviations of all angular characteristic values ​​and the average value of the deviations of all characteristic position coordinate values ​​of each laser system;

[0033] Step S106: When the average deviations of all angle characteristic values ​​of all laser systems and the average deviations of all characteristic position coordinate values ​​are within the allowable error range, turn on the illumination light source to continue printing the workpiece to be printed; otherwise, stop printing the workpiece to be printed.

[0034] The present invention further provides a 3D printing device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the 3D printing method described above when executing the computer program.

[0035] The 3D printing method, equipment, and laser position calibration method and device of the present invention, by adopting the above-mentioned technical solution, enable the laser position calibration method of the present invention to be directly performed in the working chamber, that is, there is no need to open the sealed door of the working chamber, and no additional calibration devices are required, so the cost is low; moreover, there are few additional steps and the calibration method is simple, and it can be started at any time before or during printing as needed; in addition, the laser position calibration method of the present invention has high working efficiency and high calibration accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A method flow chart of embodiment 1 of the laser position calibration method for a 3D printing device provided by the present invention;

[0037] Figure 2 A method flow chart of embodiment 2 of the laser position calibration method for a 3D printing device provided by the present invention;

[0038] Figure 3 A graphical schematic diagram provided by the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application. Example

[0040] like Figure 1 As shown, a laser position calibration method for a 3D printing device includes the following steps:

[0041] Step 11: Turn off the lighting source in the working chamber. This means that when the lighting source is already in the off state, no action is required and the off state can be maintained. When the lighting source is in the on state, the lighting source needs to be turned off to maintain the light ratio state.

[0042] Step 12: Control at least one laser system to fire a laser according to a preset program in the powder-laid work area. The laser energy density of the laser is lower than the unit density melting heat of the powder and is capable of interacting with the powder (e.g., igniting the powder). Preferably, the laser energy density is 65%-75% of the unit density melting heat of the powder. This not only ignites the powder but also has little impact on its properties. It should be noted that, aside from keeping the illumination light source off, the working chamber's environmental factors are essentially the same as those for part printing, such as ensuring the presence of protective gas and a smooth powder surface.

[0043] When there is only one laser system, the laser system emits laser on the powder in the working area according to a preset program to ignite the powder; when there are two or more laser systems, the two adjacent laser systems emit laser on the powder in the splicing area according to a preset program to ignite the powder, and the trajectories of the powder ignited by the two adjacent laser systems correspond one to one.

[0044] Step 13. Use a detector (the detector in this embodiment can be a camera, of course, in this application, the detector can also be other devices with the function of taking pictures) to record the trajectory of the laser igniting the powder to form an image to be processed; in a specific implementation, the image to be processed includes at least two intersecting line segments. It should be noted here that the preset program is a pre-set laser printing program, through which the laser system ignites various graphics on the powder, and the graphics are photographed under long exposure of the camera to form the image to be processed. In a specific implementation, the camera can capture once, and for complex graphics, it can also capture multiple times to obtain multiple pictures, and finally obtain the final image to be processed by splicing. The features include angle features and feature position coordinates. Of course, in a specific implementation, it can also select other features and graphics of other shapes, which are not listed here one by one.

[0045] Step 14: Acquire several features of the image to be processed, and calibrate the laser system by analyzing the several features. Example

[0046] like Figure 2 As shown, the laser position calibration method of the 3D printing device of this embodiment includes the following steps:

[0047] Step 21: Turn off the lighting source in the working chamber;

[0048] Step 22: Control at least one laser system to emit laser light according to a preset program in a working area where the powder has been laid, wherein the laser energy density of the laser light is lower than the unit density melting heat of the powder and can ignite the powder; Figure 1 Shown is one of at least one pattern formed by ignition of the powder by the laser system according to a preset program;

[0049] Step 23: Using a camera to record the trajectory of the laser igniting the powder to form an image to be processed (for example, the image to be processed includes four graphics);

[0050] Step 24: Calculate all angle feature values ​​and feature position coordinate values ​​in the image to be processed, and calculate their deviations from the corresponding theoretical values.

[0051] Step 25 : Calculate the average value of the deviations of all angle characteristic values ​​and the average value of the deviations of all characteristic position coordinate values, and compensate the angle and offset of the galvanometer unit of the laser system according to the average values. Example

[0052] The laser position calibration method for a 3D printing device of this embodiment includes the following steps:

[0053] Step 31: Turn off the lighting source in the working chamber;

[0054] Step 32: Control two adjacent laser systems to emit lasers on the powder in the splicing area according to a preset program to ignite the powder, wherein the laser energy density of the laser is lower than the unit density melting heat of the powder and can ignite the powder; Figure 3 Shown is one of at least one pattern formed by ignition of the powder by the laser system according to a preset program;

[0055] Step 33: Using a camera to record the trajectory of the laser igniting the powder to form an image to be processed (for example, in the image to be processed, the stitching area of ​​each of two adjacent laser systems includes two sets of corresponding images);

[0056] Step 34: Calculate all angle eigenvalues ​​in the image to be processed, and calculate the deviations of all angle eigenvalues ​​from the corresponding theoretical values. The average of all deviations is the overall angle deviation, which is the camera deflection angle.

[0057] Step 35: Rotate and correct the image to be processed according to the camera deflection angle to obtain a corrected image; and calculate all angle feature values ​​and feature position coordinate values ​​of the corrected image;

[0058] Step 36: Select one laser system as a reference laser system. At least one angle characteristic value and characteristic position coordinate value corresponding to the reference laser system is used as a reference value. Using this reference value as a benchmark, theoretical angle characteristic values ​​and theoretical characteristic position coordinate values ​​corresponding to all laser systems other than the reference laser system are obtained sequentially according to the overlapping principle. The overlapping principle here includes that the patterns corresponding to adjacent laser systems are spaced 0.1 mm apart and have consistent angles. Of course, other overlapping principles in the prior art can also be used. Preferably, after the reference laser system is selected and before it is used as a reference for calibration of other laser systems, the reference laser system can be calibrated using the method of Example 2 to further improve calibration accuracy.

[0059] Step 37: Calculate the deviations of the angle characteristic values ​​and characteristic position coordinate values ​​of all laser systems except the reference laser system in the corrected image relative to the corresponding theoretical angle characteristic values ​​and theoretical characteristic position coordinate values ​​(that is, one angle characteristic value corresponds to one theoretical angle characteristic value; one characteristic position coordinate value corresponds to one theoretical characteristic position coordinate value), calculate the average value of the deviations of all angle characteristic values ​​and the average value of the deviations of all characteristic position coordinate values ​​of each laser system, and compensate for the angle and offset of the galvanometer unit of the corresponding laser system based on the average values. Example

[0060] The laser position calibration method for a 3D printing device of this embodiment includes the following steps:

[0061] Step 41: Turn off the lighting source in the working chamber;

[0062] Step 42: Control two adjacent laser systems to emit lasers on the powder in the splicing area according to a preset program to ignite the powder, wherein the laser energy density of the laser is lower than the unit density melting heat of the powder and can ignite the powder;

[0063] Step 43: Using a camera to record the trajectory of the laser igniting the powder to form an image to be processed;

[0064] Step 44: Calculate all angle eigenvalues ​​in the image to be processed, and calculate the deviations of all angle eigenvalues ​​from the corresponding theoretical values. The average of all deviations is the overall angle deviation, which is the camera deflection angle.

[0065] Step 45: Rotate and correct the image to be processed according to the camera deflection angle to obtain a corrected image; and calculate all angle feature values ​​and feature position coordinate values ​​of the corrected image;

[0066] Step 46: Select one laser system as a reference laser system. Use at least one angle characteristic value and characteristic position coordinate value corresponding to the reference laser system as a reference value. Based on the reference value, obtain the theoretical angle characteristic values ​​and theoretical characteristic position coordinate values ​​corresponding to all laser systems except the reference laser system in sequence according to the overlapping principle.

[0067] Step 47: Calculate the deviations of the angle characteristic values ​​and characteristic position coordinate values ​​of all laser systems except the reference laser system in the corrected image relative to the corresponding theoretical angle characteristic values ​​and theoretical characteristic position coordinate values, respectively. Calculate the average value of the deviations of all angle characteristic values ​​and the average value of the deviations of all characteristic position coordinate values ​​of each laser system, and compensate for the angle and offset of the galvanometer unit of the corresponding laser system based on the average values.

[0068] Step 48: Control two adjacent laser systems to emit laser light on the powder in the splicing area according to a preset program to ignite the powder (the preset program is the same as the preset program in step 42). The laser light has a laser energy density lower than the unit density melting heat of the powder and can ignite the powder.

[0069] Step 49: Use a camera to record the trajectory of the laser igniting the powder to form an image to be processed, and use the camera deflection angle obtained in step 44 to rotationally correct the image to be processed, and obtain at least one angle characteristic value and characteristic position coordinate value of each laser system in the corrected image as an initial reference value. Example

[0070] The laser position calibration device of the 3D printing device of this embodiment includes a memory and a processor, wherein the memory stores a computer program, wherein the processor implements the steps of the laser position calibration method of the 3D printing device described in any one of the above-mentioned embodiments 1 to 4 when executing the computer program. Example

[0071] The 3D printing method of this embodiment includes the following steps:

[0072] After the printed part reaches a first preset number of layers, the laser position calibration method for the 3D printing device described in any one of Examples 1 through 4 is initiated to calibrate the laser system. The first preset number of layers can be 0 or any other arbitrary number, and is, of course, less than the total number of layers in the printed part. In other words, the laser position calibration method for the 3D printing device described in any one of Examples 1 through 4 can be initiated at any time, as needed, before or during the sintering process of the 3D print to calibrate the laser system. Example

[0073] In a multi-laser splicing 3D printing device, in order to further verify the accuracy of calibration and better ensure the sintering quality of the printed part, the 3D printing method of this embodiment includes the following steps:

[0074] Step 71: After the workpiece to be printed reaches a first preset number of layers, the laser position calibration method of the 3D printing device described in the fourth embodiment is started to calibrate the laser system.

[0075] Step 72: After the calibration is completed, the illumination light source is turned on to continue printing the workpiece to be printed. When the workpiece to be printed reaches the second preset number of layers, the illumination light source in the working chamber is turned off. The first preset number of layers can be any number, such as 0 or 1, 2, 3, etc. The second preset number of layers can be any number, but the second preset number of layers is greater than the second preset number of layers, and can be specifically set according to design requirements.

[0076] Step 73: Two adjacent laser systems emit lasers at the powder in the splicing area according to a preset program to ignite the powder (this preset program is the same as the preset program in Example 4). The laser energy density of the laser is lower than the unit density melting heat of the powder and can ignite the powder.

[0077] Step 74: Use a detector (in this embodiment, the detector is a camera) to record the trajectory of the laser igniting the powder to form an image to be processed, and use the camera deflection angle obtained in step 44 to perform rotation correction on the image to be processed, and obtain the angular characteristic value and characteristic position coordinate value of each laser system in the corrected image.

[0078] Step 75: Calculate the deviations of the angular characteristic values ​​and characteristic position coordinate values ​​of all laser systems relative to the corresponding initial reference values ​​in step 49, and calculate the average value of the deviations of all angular characteristic values ​​and the average value of the deviations of all characteristic position coordinate values ​​of each laser system;

[0079] Step 76: When the average value of the deviation of all angle characteristic values ​​of all laser systems and the average value of the deviation of all characteristic position coordinate values ​​are both within the allowable error range (the specific value of the allowable error range can be determined by the designer or can be a well-known technology for those skilled in the art), turn on the illumination light source to continue printing the workpiece to be printed; otherwise, stop printing the workpiece to be printed. Example

[0080] This embodiment provides a 3D printing device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the 3D printing method described in the seventh embodiment are implemented.

[0081] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0082] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A laser position calibration method for a 3D printing device, characterized in that: The following steps are involved: Step S1, turning off the lighting source in the working chamber; Step S2, controlling at least one laser system to emit laser light according to a preset program in a working area where the powder has been laid, wherein the laser light has a laser energy density lower than the unit density melting heat of the powder and can interact with the powder; Step S3: using a detector to record the trajectory of the laser acting on the powder to form an image to be processed; Step S4: obtaining several features of the image to be processed, and calibrating the laser system by analyzing the several features; The image to be processed includes at least two intersecting line segments, the features include angle features and feature position coordinates; the detector is a camera; wherein, When there is only one laser system, the step S4 of calibrating the laser system by analyzing several features specifically includes: Step S411: Calculate all angle feature values ​​and feature position coordinate values ​​in the image to be processed, and calculate their deviations from the corresponding theoretical values. Step S412, respectively calculating the average value of the deviations of all angle characteristic values ​​and the average value of the deviations of all characteristic position coordinate values, and compensating the angle and offset of the galvanometer unit of the laser system according to the average values; When there are two or more laser systems, the calibration of the laser systems by analyzing several features in step S4 specifically includes: Step S421: Calculate all angle eigenvalues ​​in the image to be processed, and calculate the deviations of all angle eigenvalues ​​from the corresponding theoretical values. The average of all deviations is the overall angle deviation, which is the camera deflection angle. Step S422: Rotate and correct the image to be processed according to the camera deflection angle to obtain a corrected image; and calculate all angle feature values ​​and feature position coordinate values ​​of the corrected image; Step S423: Select one laser system as a reference laser system, and use at least one angle characteristic value and characteristic position coordinate value corresponding to the reference laser system as a reference value. Based on the reference value, theoretical angle characteristic values ​​and theoretical characteristic position coordinate values ​​corresponding to all laser systems except the reference laser system are obtained in sequence according to the overlapping principle. Step S424, calculate the deviations of the angle characteristic values ​​and characteristic position coordinate values ​​of all laser systems except the reference laser system in the corrected image relative to the corresponding theoretical angle characteristic values ​​and theoretical characteristic position coordinate values, calculate the average value of the deviations of all angle characteristic values ​​and the average value of the deviations of all characteristic position coordinate values ​​of each laser system, and compensate for the angle and offset of the galvanometer unit of the corresponding laser system according to the average value.

2. The laser position calibration method for a 3D printing device according to claim 1, characterized in that: When there is only one laser system, the laser system emits laser on the powder in the working area according to a preset program to interact with the powder; when there are two or more laser systems, the two adjacent laser systems emit laser on the powder in the splicing area according to a preset program to interact with the powder, and the trajectories of the two adjacent laser systems acting on the powder correspond one to one.

3. The laser position calibration method for a 3D printing device according to claim 2, characterized in that: The step S4 further includes the following steps: Step S5, controlling at least one laser system to emit laser light according to a preset program in a working area where the powder has been laid, wherein the laser light has a laser energy density lower than the unit density melting heat of the powder and can interact with the powder; Step S6: Use a camera to record the trajectory of the above-mentioned laser when it acts on the powder to form an image to be processed, and use the camera deflection angle obtained in step S421 to rotationally correct the image to be processed, and obtain at least one angle characteristic value and characteristic position coordinate value of each laser system in the corrected image as an initial reference value.

4. A laser position calibration device for a 3D printing device, characterized in that: The method comprises a memory and a processor, wherein the memory stores a computer program, and is characterized in that when the processor executes the computer program, the steps of the laser position calibration method for a 3D printing device according to any one of claims 1 to 3 are implemented.

5. A 3D printing method, characterized in that: The following steps are involved: When the workpiece to be printed has been printed to a first preset number of layers, the laser position calibration method for the 3D printing device according to any one of claims 1 to 3 is started to calibrate the laser system.

6. A 3D printing method, characterized in that: The following steps are involved: Step S101: After the workpiece to be printed reaches a first preset number of layers, the laser position calibration method of the 3D printing device according to claim 3 is started to calibrate the laser system; Step S102: After the calibration is completed, the illumination light source is turned on to continue printing the workpiece to be printed. After the workpiece to be printed reaches a second preset number of layers, the illumination light source in the working chamber is turned off. Step S103: Control at least one laser system to emit laser light according to a preset program in a working area where the powder has been laid, wherein the laser light has a laser energy density lower than the unit density melting heat of the powder and can interact with the powder; Step S104: Using a detector to record the trajectory of the laser when it acts on the powder to form an image to be processed, and using the camera deflection angle obtained in step S421 to perform rotation correction on the image to be processed, respectively obtaining the angle characteristic value and characteristic position coordinate value of each laser system in the corrected image; Step S105: Calculate the deviations of the angular characteristic values ​​and characteristic position coordinate values ​​of all laser systems relative to the corresponding initial reference values ​​in step S6, and calculate the average value of the deviations of all angular characteristic values ​​and the average value of the deviations of all characteristic position coordinate values ​​of each laser system; Step S106: When the average deviations of all angle characteristic values ​​of all laser systems and the average deviations of all characteristic position coordinate values ​​are within the allowable error range, turn on the illumination light source to continue printing the workpiece to be printed; otherwise, stop printing the workpiece to be printed.

7. A 3D printing device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the 3D printing method according to claim 5 or 6 are implemented.

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