3D printing process monitoring system and method based on high-speed two-dimensional galvanometer

Abstract

The application relates to the technical field of 3D printing, in particular to a 3D printing process monitoring system and method based on a high-speed two-dimensional swing mirror. The application sets a high-speed two-dimensional swing mirror in front of the object light path of an imaging lens group, realizes rapid optical scanning of a working surface, and controls the working surface to be divided into a target point array first, then calculates a diopter point array of a liquid zoom lens according to the current printing layer number and the object distance of each point; in the actual detection process, the controller drives the high-speed two-dimensional swing mirror to point to each target point in turn, and controls the liquid zoom lens to adjust the focal length according to the preset diopter point array in real time, so that the industrial camera can obtain a clear image at each point; the application not only solves the high-precision imaging problem in a large field of view, but also avoids the adverse effects caused by mechanical vibration through pure optical scanning; the whole detection process is more efficient, the system structure is simple, and the detection precision and reliability are improved.

Description

Technical Field

[0001] This application relates to the technical field of 3D printing, and in particular to a 3D printing process monitoring system and method based on a high-speed two-dimensional oscillating mirror. Background Technology

[0002] With the rapid development of 3D printing technology, metal 3D printing has gradually moved from the laboratory stage to industrial applications. In high-end manufacturing fields such as aerospace and medical devices, the quality requirements for 3D printed parts are becoming increasingly stringent, making real-time quality monitoring during the printing process a crucial step in ensuring product quality.

[0003] Existing 3D printing process monitoring technologies primarily employ fixed top-mounted camera imaging schemes, which use high-resolution industrial cameras installed on the top of the printing chamber to perform overall imaging and inspection of the working surface. Additionally, technologies utilizing laser contour scanning acquire the three-dimensional contour data of the printed layers through line scanning.

[0004] However, fixed top cameras must use small focal length lenses to obtain a sufficient field of view, which reduces resolution; while using mechanical displacement to expand the field of view reduces detection efficiency and introduces mechanical vibration interference; adopting a multi-camera solution will significantly increase system cost and complexity, and this situation needs further improvement. Summary of the Invention

[0005] To achieve rapid detection with a large field of view while ensuring detection accuracy, avoiding mechanical vibration interference, and maintaining a simple system structure and low cost, this application provides a 3D printing process monitoring system and method based on a high-speed two-dimensional tilting mirror, adopting the following technical solution:

[0006] In a first aspect, this application provides a 3D printing process monitoring system based on a high-speed two-dimensional tilting mirror, comprising:

[0007] Industrial camera, imaging lens group consisting of fixed-focus lens and liquid zoom lens, high-speed two-dimensional tilting mirror and controller;

[0008] The high-speed two-dimensional tilting mirror is positioned in front of the object-side optical path of the imaging lens group to receive light from the working surface of the 3D printing equipment and reflect it to the imaging lens group.

[0009] The imaging lens group is disposed between the high-speed two-dimensional oscillating mirror and the industrial camera, and is used to converge the reflected light and image it on the sensor of the industrial camera;

[0010] The controller is electrically connected to the driving unit of the industrial camera, the driving unit of the liquid zoom lens, and the driving unit of the high-speed two-dimensional tilting mirror, respectively.

[0011] The controller is configured to perform the following operations:

[0012] The working surface is divided into a target point matrix;

[0013] The diopter matrix of the liquid zoom lens is determined based on the current number of printed layers and the object distance of each point in the target matrix.

[0014] The high-speed two-dimensional swing mirror is controlled to swing sequentially so that the imaging optical path is aligned with each point in the target array;

[0015] When the high-speed two-dimensional tilting mirror reaches each point, the liquid zoom lens is controlled to adjust to the corresponding diopter according to the diopter dot matrix for focusing;

[0016] The industrial camera is controlled to acquire images at the focus point to achieve regional monitoring of the working surface.

[0017] By adopting the above technical solution, this application proposes a 3D printing process monitoring system based on a high-speed two-dimensional tilting mirror. A high-speed two-dimensional tilting mirror is placed in front of the object-side optical path of the imaging lens group to achieve rapid optical scanning of the working surface. The controller first divides the working surface into target point arrays, and then calculates the diopter array of the liquid zoom lens based on the current number of printing layers and the object distance at each point. During actual inspection, the controller drives the high-speed two-dimensional tilting mirror to point sequentially at each target point, while simultaneously controlling the liquid zoom lens to adjust its focal length in real time according to the preset diopter array, ensuring that the industrial camera can obtain a clear image at each point. This not only solves the problem of high-precision imaging over a large field of view, but also avoids the adverse effects of mechanical vibration through pure optical scanning. The entire inspection process is more efficient, the system structure is simple, and the inspection accuracy and reliability are improved.

[0018] Optionally, the fixed-focus lens is a telephoto lens.

[0019] By adopting the above technical solution, since the detection system needs to avoid interfering with the printing process, the monitoring equipment is usually installed at a position far away from the working surface. The telephoto lens has a large working distance and can obtain a narrow field of view and a high magnification at a distance. In combination with the high-speed two-dimensional tilting mirror, high-precision imaging can be achieved.

[0020] Optionally, the controller is further configured to:

[0021] Receive powder spreading start signal or sintering start signal from 3D printing equipment;

[0022] After receiving the powder spreading start signal, the point scanning and image acquisition will begin after a first preset time delay to perform powder spreading quality detection.

[0023] After receiving the sintering start signal, the point scanning and image acquisition are performed after a second preset time delay to detect the sintering quality.

[0024] By adopting the above technical solution, the powder spreading and sintering processes have different characteristics in actual printing: after powder spreading, it is necessary to wait for the powder layer to stabilize, and after sintering, it is necessary to wait for the molten pool to cool down, both of which affect the accuracy of detection. In this application, when the powder spreading start signal is received, the controller delays for a first preset time, waiting for the powder layer to be fully spread and stabilized before starting the point scanning and image acquisition, thereby accurately evaluating the powder spreading quality. When the sintering start signal is received, the controller delays for a second preset time, waiting for the molten pool temperature to drop to an appropriate level before detection, to ensure that the true surface state after sintering is obtained. Through the intelligent delay control strategy based on process characteristics, the accuracy of detection is improved, the detection process is automated, manual intervention is reduced, and production efficiency is improved.

[0025] Optionally, the controller is further configured to:

[0026] Based on the type of the received start signal, the target image analysis model is automatically invoked. The start signal type includes the powder spreading start signal and the sintering start signal. The target image analysis model includes the image analysis model corresponding to powder spreading detection and the image analysis model corresponding to sintering detection.

[0027] The system also includes an image processing unit that is communicatively connected to the controller, used for asynchronous detection and analysis of the acquired images.

[0028] By adopting the above technical solutions, the key points and evaluation criteria for powder spreading and sintering processes in 3D printing differ significantly: powder spreading quality mainly focuses on the uniformity and flatness of the powder layer, while sintering quality requires evaluation of the molten pool morphology and surface defects. This application calls a dedicated algorithm model for powder layer morphology analysis during powder spreading inspection, and switches to a molten pool and surface quality analysis model during sintering inspection. Simultaneously, the system introduces an independent image processing unit, employing an asynchronous processing mechanism to allow image acquisition and analysis to proceed in parallel. When the controller directs the high-speed two-dimensional tilting mirror to continue scanning the next area, previously acquired images can be analyzed synchronously in the image processing unit, effectively improving overall inspection efficiency. This not only enhances the targeting and accuracy of inspection but also improves the system's real-time performance. Notably, the high-speed two-dimensional tilting mirror used in this application scans much faster than the scraper movement speed and powder spreading speed of the 3D printing equipment. Combined with the asynchronous image processing mechanism, this allows the entire inspection process to be completed before the equipment executes the next process, without pausing or delaying the normal operating cycle of the equipment. For example, after one layer of printing is completed, the system can complete the sintering quality inspection before the scraper starts working; similarly, when the powder spreading process starts, the inspection and analysis of the previous process has already been completed; this ensures that production efficiency will not decrease due to the addition of inspection steps, making the time of the entire printing process consistent with that without the monitoring system installed, while also obtaining comprehensive quality monitoring data, thus achieving a balance between inspection efficiency and production efficiency.

[0029] Optionally, the diopter matrix of the liquid zoom lens is determined by a pre-calibrated linear relationship between object distance and diopter.

[0030] By adopting the above technical solution, during the 3D printing process, there are differences in the object distance between different positions of the working surface and the lens, requiring the liquid zoom lens to perform real-time focusing adjustment. Before use, this application conducts calibration experiments, and by measuring the corresponding optimal diopter values ​​under different known object distances, a linear function relationship between object distance and diopter is fitted. In the actual testing process, the controller can directly use this linear relationship to quickly calculate the required diopter value based on the object distance of the target point, without the need for complex iterative calculations.

[0031] Secondly, this application provides a 3D printing process monitoring method based on a high-speed two-dimensional oscillating mirror. The method, using the aforementioned 3D printing process monitoring system based on a high-speed two-dimensional oscillating mirror, includes the following steps:

[0032] Divide the working surface of the 3D printing equipment into a target dot matrix;

[0033] The diopter matrix of the liquid zoom lens is determined based on the current number of printed layers and the object distance of each point in the target matrix.

[0034] Control the high-speed two-dimensional tilting mirror to swing sequentially, so that the imaging optical path composed of the high-speed two-dimensional tilting mirror, the liquid zoom lens and the fixed-focus lens is aligned with each point in the target dot array.

[0035] When the high-speed two-dimensional tilting mirror reaches each point, the liquid zoom lens is controlled to adjust to the corresponding diopter according to the diopter dot matrix for focusing;

[0036] Control the industrial camera to acquire images at the focus point to achieve regional monitoring of the working surface.

[0037] Optionally, before the step of controlling the high-speed two-dimensional pendulum mirror to swing sequentially, the following steps are also included:

[0038] Receive powder spreading start signal or sintering start signal from 3D printing equipment;

[0039] If a powder spreading start signal is received, the point scanning and image acquisition process will begin after a first preset time delay to perform powder spreading quality detection.

[0040] If a sintering start signal is received, the point scanning and image acquisition process will begin after a second preset time delay to perform sintering quality inspection.

[0041] Optionally, the following steps may also be included:

[0042] Based on the type of the received start signal, the target image analysis model is automatically invoked. The start signal type includes the powder spreading start signal and the sintering start signal. The target image analysis model includes the image analysis model corresponding to powder spreading detection and the image analysis model corresponding to sintering detection.

[0043] After acquiring images, the industrial camera transmits the images to the image processing unit for asynchronous detection and analysis.

[0044] Optionally, determining the diopter grid of the liquid zoom lens includes the following steps:

[0045] By using a pre-calibrated linear relationship between object distance and diopter, the diopter corresponding to each point in the target dot matrix at the current number of printing layers is calculated to form the diopter dot matrix.

[0046] Optionally, the step of dividing the working surface into the target point matrix includes the following steps:

[0047] Based on the dimensions of the working surface and the field of view of the industrial camera, the working surface is divided into a grid of C rows and R columns, P[C][R].

[0048] The diopter matrix is ​​represented as F[C][R][N], where N is the current number of printed layers.

[0049] By adopting the above technical solution, this application first divides the entire working surface into a regular grid P[C][R] of C rows and R columns according to the actual size of the working surface and the effective field of view of the camera, ensuring that adjacent scanning areas have appropriate overlap and avoiding monitoring blind spots; then, a three-dimensional array structure F[C][R][N] is established to store diopter data, where C and R correspond to the row and column positions of the grid, respectively, and N represents the current printing layer number; this not only facilitates the controller to plan the scanning path, but also realizes the hierarchical management of diopter parameters of different printing layers.

[0050] In summary, this application includes at least one of the following beneficial technical effects:

[0051] This application achieves rapid optical scanning of the working surface by setting a high-speed two-dimensional tilting mirror in front of the object-side optical path of the imaging lens group. The controller first divides the working surface into target dot matrix, and then calculates the refractive power dot matrix of the liquid zoom lens based on the current number of printing layers and the object distance of each dot. During the actual inspection process, the controller drives the high-speed two-dimensional tilting mirror to point to each target dot in sequence, while controlling the liquid zoom lens to adjust the focal length in real time according to the preset refractive power dot matrix, ensuring that the industrial camera can obtain a clear image at each dot. This not only solves the problem of high-precision imaging over a large field of view, but also avoids the adverse effects of mechanical vibration through pure optical scanning. The entire inspection process is more efficient, the system structure is simple, and the inspection accuracy and reliability are improved.

[0052] In actual printing, the powder spreading and sintering processes have different characteristics: after powder spreading, it is necessary to wait for the powder layer to stabilize, and after sintering, it is necessary to wait for the molten pool to cool down. These factors can affect the accuracy of the detection. In this application, when the powder spreading start signal is received, the controller delays for a first preset time, waiting for the powder layer to be fully spread and stabilized before starting the dot scanning and image acquisition, thereby accurately assessing the powder spreading quality. When the sintering start signal is received, the controller delays for a second preset time, waiting for the molten pool temperature to drop to an appropriate level before performing the detection, to ensure that the true surface state after sintering is obtained. Through the intelligent delay control strategy based on process characteristics, the accuracy of the detection is improved, the detection process is automated, manual intervention is reduced, and production efficiency is improved.

[0053] In the 3D printing process, the inspection focus and evaluation criteria for powder spreading and sintering processes differ significantly: powder spreading quality mainly focuses on the uniformity and flatness of the powder layer, while sintering quality requires evaluation of the molten pool morphology and surface defects. This application calls a dedicated algorithm model for powder layer morphology analysis during powder spreading inspection, and switches to a molten pool and surface quality analysis model during sintering inspection. Simultaneously, the system introduces an independent image processing unit, employing an asynchronous processing mechanism to allow image acquisition and analysis to proceed in parallel. When the controller directs the high-speed 2D pendulum mirror to continue scanning the next area, previously acquired images can be simultaneously analyzed in the image processing unit, effectively improving overall inspection efficiency. This not only enhances the targeting and accuracy of inspection but also improves the system's real-time performance. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the system structure of the 3D printing process monitoring system based on a high-speed two-dimensional oscillating mirror according to an embodiment of this application;

[0055] Figure 2 This is a system workflow diagram of the 3D printing process monitoring system based on a high-speed two-dimensional oscillating mirror according to an embodiment of this application;

[0056] Figure 3 This is a schematic diagram of the 3D printing process monitoring method based on a high-speed two-dimensional pendulum mirror according to an embodiment of this application. Detailed Implementation

[0057] The terminology used in the following embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. As used in the specification and appended claims of this application, the singular expressions “a,” “an,” “the,” “the,” “the,” and “this” are intended to include the plural expressions as well, unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this application refers to any or all possible combinations including one or more of the listed items.

[0058] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature, and in the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more.

[0059] The embodiments of this application will now be described in further detail with reference to the accompanying drawings.

[0060] In a first aspect, the 3D printing process monitoring system based on a high-speed two-dimensional tilting mirror provided in this application includes an industrial camera, an imaging lens group, a high-speed two-dimensional tilting mirror, and a controller. The high-speed two-dimensional tilting mirror is positioned in front of the object-side optical path of the imaging lens group, which is positioned between the high-speed two-dimensional tilting mirror and the industrial camera. The controller is electrically connected to the driving units of the industrial camera, the liquid zoom lens, and the high-speed two-dimensional tilting mirror. The high-speed two-dimensional tilting mirror can rapidly change the direction of light propagation, enabling the imaging optical path to be aligned with different points on the working surface. The imaging lens group can converge reflected light and image it onto the sensor of the industrial camera. The controller can control the operation of each component according to a preset program.

[0061] Specifically, the imaging lens assembly consists of a fixed-focus lens and a liquid zoom lens. The fixed-focus lens can be a telephoto lens, which offers high resolution and can capture detailed information about the working surface. Besides telephoto lenses, other types of lenses, such as standard lenses, can also be used to meet different monitoring needs. The drive unit of the liquid zoom lens can adjust its diopter to achieve focusing. Liquid zoom lenses typically consist of a liquid and a deformable diaphragm. By changing the pressure or electric field of the liquid, the shape of the diaphragm is altered, thus changing the lens's diopter. Liquid zoom lenses offer advantages such as fast focusing speed and no mechanical vibration. The drive unit of the liquid zoom lens can be an electric drive unit or a hydraulic drive unit, etc.

[0062] A high-speed 2D tilting mirror consists of a reflector and a drive mechanism. The reflector receives light from the working surface of the 3D printing equipment and reflects it to the imaging lens assembly. The reflector is typically made of a high-reflectivity material, such as silver-plated or aluminum-plated glass, to reduce light loss. The reflector can be circular, square, or other shapes. The drive mechanism drives the reflector to tilt, aligning the imaging light path with each point in the target dot matrix. The drive mechanism can be a motor drive mechanism, such as a stepper motor or servo motor, or a piezoelectric drive mechanism.

[0063] The controller can be a microcontroller, PLC, etc. The controller is configured to perform the following operations: divide the working surface into a target dot matrix; determine the diopter dot matrix of the liquid zoom lens based on the current number of printing layers and the object distance of each point in the target dot matrix; control the high-speed two-dimensional tilting mirror to swing sequentially, aligning the imaging optical path with each point in the target dot matrix; when the high-speed two-dimensional tilting mirror reaches each point, control the liquid zoom lens to adjust to the corresponding diopter according to the diopter dot matrix for focusing; and control the industrial camera to acquire images at the focus point to achieve regional monitoring of the working surface. The controller achieves precise control of the entire system through electrical connections with various components.

[0064] Reference Figure 1A high-speed two-dimensional tilting mirror is positioned at the front of the object-side optical path of the imaging lens assembly to reflect light from the working surface to the imaging lens assembly. The working surface is divided into a 3×3 grid area (points 1 to 9), and the high-speed two-dimensional tilting mirror scans each area sequentially by changing its angle. The imaging lens assembly, located between the high-speed two-dimensional tilting mirror and the industrial camera, includes a liquid zoom lens and a fixed-focus lens to converge the reflected light into an image. The controller is electrically connected to the industrial camera, the liquid zoom lens drive unit, and the high-speed two-dimensional tilting mirror drive unit to coordinate and control the operation of the entire system. The system also includes a host computer and a display. The host computer processes the acquired image data, and the display shows the detection results in real time. Control signals and data are transmitted between the various components via a control bus to achieve coordinated operation of the system.

[0065] In one embodiment, the controller is further configured to receive a powder spreading start signal or a sintering start signal from the 3D printing equipment. Upon receiving the powder spreading start signal, it initiates point scanning and image acquisition after a first preset time delay to perform powder spreading quality detection. Upon receiving the sintering start signal, it initiates point scanning and image acquisition after a second preset time delay to perform sintering quality detection. This allows for corresponding quality detection based on different printing stages, improving the targeting and accuracy of monitoring.

[0066] In one possible embodiment, the first preset time needs to consider the settling and stabilization process of the metal powder after powder spreading. The powder spreading process of different materials is observed using a high-speed camera, and the time required from the completion of powder spreading to the complete stabilization of the powder layer is recorded. For example, for titanium alloy powder with a particle size of 20-50 micrometers, experiments show that a stabilization time of 0.5-1 second is required; while for stainless steel powder with a smaller particle size, a stabilization time of 1-2 seconds may be required. The second preset time needs to be determined based on the cooling characteristics of the molten pool after laser sintering. The temperature change curves of the molten pool under different materials and different laser powers are monitored using an infrared thermal imager to determine the time required for the temperature to drop to a suitable detection range. For example, for high-temperature alloy materials, a cooling time of 2-3 seconds may be required to avoid interference from thermal radiation on the imaging. This application first establishes a material parameter data table, including physical property parameters such as powder particle size, density, and flowability of different materials. Then, powder spreading experiments are conducted for each material, and the stabilization process of the powder layer is recorded using a high-speed camera to obtain the first preset time T1; simultaneously, laser sintering experiments are conducted, and the cooling curves of the molten pool under different powers are recorded using an infrared thermal imager to obtain the second preset time T2. The acquired material parameters and their corresponding T1 and T2 values ​​are stored in a database, establishing a material-delay time correspondence. During system operation, the corresponding delay parameters are automatically retrieved from the database based on the current printing material: when a powder spreading start signal is received, the T1 value corresponding to that material is read; when a sintering start signal is received, the T2 value corresponding to that material is read. Simultaneously, the system dynamically adjusts the basic delay parameters based on the laser power and scanning speed during the actual printing process. During the detection process, the system continuously collects delay effect data to optimize and update the parameter values ​​in the database.

[0067] Furthermore, the controller is configured to automatically invoke the target image analysis model based on the type of the received start signal. The start signal types include powder spreading start signals and sintering start signals. The target image analysis models include image analysis models corresponding to powder spreading detection and sintering detection. The system also includes an image processing unit communicatively connected to the controller for asynchronous detection and analysis of the acquired images. This allows for automatic selection of the appropriate image analysis model based on different start signal types, improving the accuracy and efficiency of image analysis.

[0068] Figure 2The system flowchart of an embodiment of the present invention is shown, including two main parts: initialization and initial detection. During initialization, the system first determines the size of the working surface and the camera field of view, and sets the delay parameters T1 and T2 for the powder spreading blade start signal and the laser head sintering start signal. Then, based on the working surface and camera field of view, the working surface is divided into a C×R grid P[C][R], and the number of printing layers N and the thickness of each layer are determined. After experimentally determining the linear relationship between object distance and diopter, the diopter value F[C][R][N] corresponding to each point is calculated, and finally all parameters are saved to the local database.

[0069] During the initial detection process, the system first reads relevant parameters and loads the corresponding image analysis model based on the received start signal type (powder spreading start signal or sintering start signal). For each detection point, the controller drives a high-speed two-dimensional tilting mirror to point to the target location, while simultaneously adjusting the liquid zoom lens to the corresponding diopter for focusing, and then acquires an image. The system determines whether all C×R points have been scanned; if not, it continues to the next point. The image processing unit asynchronously processes the acquired images and determines whether any anomalies exist based on the detection results. If a new start signal is received, the system waits for the corresponding preset delay time before continuing the detection process. This design not only automates the monitoring of the powder spreading and sintering processes but also improves system efficiency through an asynchronous processing mechanism.

[0070] The implementation principle of this application embodiment is as follows: the system, through the cooperation of a high-speed two-dimensional tilting mirror and a liquid zoom lens, can quickly and accurately monitor the working surface of the 3D printing equipment in different areas. The rapid tilting of the high-speed two-dimensional tilting mirror can expand the monitoring field of view, and the rapid focusing of the liquid zoom lens can ensure the clarity of the image. Compared with traditional monitoring systems, this system has the advantages of small size, low cost, high efficiency, and simple structure, and can effectively solve the problem that existing monitoring systems are difficult to balance in terms of resolution, field of view, and depth of focus. By receiving the start signal of the 3D printing equipment and performing point scanning and image acquisition at appropriate times, the system can detect the powder spreading quality and sintering quality at different printing stages, and can promptly detect problems that occur during the printing process, ensuring printing quality and improving production efficiency. In addition, the controller automatically calls the target image analysis model according to the start signal type, enabling the system to adopt different analysis methods for different printing stages. The image processing unit performs asynchronous detection and analysis on the acquired images, which can quickly and accurately analyze the images without affecting the normal operation of the system.

[0071] Secondly, this application provides a 3D printing process monitoring method based on a high-speed two-dimensional oscillating mirror. The following description of the 3D printing process monitoring method based on a high-speed two-dimensional oscillating mirror based on this application is based on the above-mentioned 3D printing process monitoring system based on a high-speed two-dimensional oscillating mirror.

[0072] Reference Figure 3 A method for monitoring the 3D printing process based on a high-speed two-dimensional swing mirror includes the following steps:

[0073] S310. Divide the working surface of the 3D printing equipment into a target dot matrix;

[0074] S320. Determine the diopter matrix of the liquid zoom lens based on the current number of printed layers and the object distance of each point in the target matrix.

[0075] S330 controls the high-speed two-dimensional tilting mirror to swing sequentially, so that the imaging optical path composed of the high-speed two-dimensional tilting mirror, the liquid zoom lens and the fixed-focus lens is aligned with each point in the target dot matrix.

[0076] S340: When the high-speed two-dimensional tilting mirror reaches each point, control the liquid zoom lens to adjust to the corresponding diopter according to the diopter dot matrix for focusing;

[0077] The S350 controls the industrial camera to acquire images at the focus point to achieve regional monitoring of the working surface.

[0078] In one embodiment, before the step of controlling the high-speed two-dimensional pendulum mirror to swing sequentially, the following step is also included:

[0079] Receive powder spreading start signal or sintering start signal from 3D printing equipment;

[0080] If a powder spreading start signal is received, the point scanning and image acquisition process will begin after a first preset time delay to perform powder spreading quality detection.

[0081] If a sintering start signal is received, the point scanning and image acquisition process will begin after a second preset time delay to perform sintering quality inspection.

[0082] In one embodiment, the following steps are also included:

[0083] Based on the type of the received start signal, the target image analysis model is automatically invoked. The start signal types include powder spreading start signal and sintering start signal, and the target image analysis model includes the image analysis model corresponding to powder spreading detection and the image analysis model corresponding to sintering detection.

[0084] After the industrial camera acquires images, it transmits the images to the image processing unit for asynchronous detection and analysis.

[0085] In one embodiment, determining the diopter matrix of a liquid zoom lens includes the following steps:

[0086] By using the pre-calibrated linear relationship between object distance and diopter, the diopter corresponding to each point in the target dot matrix at the current number of printing layers is calculated to form a diopter dot matrix.

[0087] In one embodiment, the step of dividing the working surface into a target lattice specifically includes the following steps:

[0088] Based on the dimensions of the working surface and the field of view of the industrial camera, the working surface is divided into a grid of C rows and R columns, P[C][R].

[0089] The diopter matrix is ​​represented as F[C][R][N], where N is the current number of printed layers.

[0090] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0091] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, or optical storage, etc. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0092] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for monitoring the 3D printing process based on a high-speed two-dimensional pendulum mirror, characterized in that, The application uses a 3D printing process monitoring system based on a high-speed two-dimensional oscillating mirror. The system includes: Industrial camera, imaging lens group consisting of fixed-focus lens and liquid zoom lens, high-speed two-dimensional tilting mirror and controller; The high-speed two-dimensional tilting mirror is positioned in front of the object-side optical path of the imaging lens group to receive light from the working surface of the 3D printing equipment and reflect it to the imaging lens group. The imaging lens group is disposed between the high-speed two-dimensional oscillating mirror and the industrial camera, and is used to converge the reflected light and image it on the sensor of the industrial camera; The controller is electrically connected to the driving unit of the industrial camera, the driving unit of the liquid zoom lens, and the driving unit of the high-speed two-dimensional tilting mirror, respectively. The controller is configured to perform the following operations: The working surface is divided into a target point matrix. Based on the current number of printed layers and the object distance of each point in the target dot matrix, the diopter dot matrix of the liquid zoom lens is determined. The high-speed two-dimensional tilting mirror is controlled to swing sequentially, aligning the imaging optical path with each point in the target array. When the high-speed two-dimensional tilting mirror reaches each point, the liquid zoom lens is controlled to adjust to the corresponding diopter according to the diopter matrix for focusing. The industrial camera is controlled to acquire images at the focus point to achieve regional monitoring of the working surface; The method includes the following steps: Divide the working surface of the 3D printing equipment into a target dot matrix; The diopter matrix of the liquid zoom lens is determined based on the current number of printed layers and the object distance of each point in the target matrix. Control the high-speed two-dimensional tilting mirror to swing sequentially, so that the imaging optical path composed of the high-speed two-dimensional tilting mirror, the liquid zoom lens and the fixed-focus lens is aligned with each point in the target dot array. When the high-speed two-dimensional tilting mirror reaches each point, the liquid zoom lens is controlled to adjust to the corresponding diopter according to the diopter dot matrix for focusing; Control the industrial camera to acquire images at the focus point to achieve regional monitoring of the working surface; Prior to the step of controlling the high-speed two-dimensional pendulum mirror to swing sequentially, the following steps are also included: Receive powder spreading start signal or sintering start signal from 3D printing equipment; If a powder spreading start signal is received, the point scanning and image acquisition process will begin after a first preset time delay to perform powder spreading quality detection. If a sintering start signal is received, the point scanning and image acquisition process will begin after a second preset time delay to perform sintering quality inspection. Based on the type of the received start signal, the target image analysis model is automatically invoked. The start signal type includes the powder spreading start signal and the sintering start signal. The target image analysis model includes an image analysis model corresponding to powder spreading quality detection and an image analysis model corresponding to sintering quality detection. After the industrial camera acquires images, it transmits the images to the image processing unit for asynchronous detection and analysis. Determining the diopter grid of a liquid zoom lens includes the following steps: By using a pre-calibrated linear relationship between object distance and diopter, the diopter corresponding to each point in the target dot matrix at the current number of printing layers is calculated to form the diopter dot matrix.

2. The 3D printing process monitoring method based on a high-speed two-dimensional oscillating mirror according to claim 1, characterized in that, The fixed-focus lens is a telephoto lens.

3. The 3D printing process monitoring method based on a high-speed two-dimensional pendulum mirror according to claim 1, characterized in that, The steps involved in dividing the working surface into a target point matrix include the following: Based on the dimensions of the working surface and the field of view of the industrial camera, the working surface is divided into a grid of C rows and R columns, P[C][R]. The diopter matrix is ​​represented as F[C][R][N], where N is the current number of printed layers.

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