Online nondestructive testing method and equipment for processing additive manufacturing signals by using image method

Abstract

The invention provides an on-line nondestructive testing method and equipment for processing an additive manufacturing signal by using an image method. The method comprises the following steps: installing detection equipment, and adjusting a light path of the detection equipment and a focal length of a lens; importing a required part CAD file into a program of the detection equipment, setting process parameters required by printing, and starting additive manufacturing; a controller with a signal acquisition card in the detection equipment is used for receiving the ultrasonic wave signal sent by the laser interferometer, the amplitude value of the ultrasonic surface wave signal is recorded once every set time, and the controller stores the amplitude value of the surface wave signal collected by the layer as a file every time the recording of the layer is finished until the additive manufacturing forming is finished; carrying out data processing on the recorded value of each layer and forming image analysis; the printing layer forming condition is simulated in real time through the processed data, and the defect type and size are judged. According to the method, the defects in the forming process can be displayed on line, the subsequent detection cost is reduced, the forming parameters are rapidly optimized, and the additive manufacturing efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and in particular to an online nondestructive testing method and device for processing additive manufacturing signals using an image method. Background Art

[0002] Metal additive manufacturing is one of the most cutting-edge and promising additive manufacturing technologies and an important development direction of advanced manufacturing technology.

[0003] Traditional nondestructive testing methods such as ultrasound and X-ray have many shortcomings in laser additive manufacturing quality inspection, including difficulty in detecting internal defects such as tiny cracks and pores; high cost, large investment in equipment and technology; slow detection speed, unable to meet the real-time requirements of laser additive manufacturing; difficult to deal with parts with complex shapes, and there are limitations; professional personnel are required to operate, which increases the cost and complexity of quality inspection. These shortcomings limit the application of traditional nondestructive testing methods in laser additive manufacturing quality inspection, and new technologies and methods need to be sought to overcome these problems to ensure the quality and reliability of laser additive manufacturing products. Summary of the invention

[0004] In view of the defects in the prior art, the present invention provides an online non-destructive testing method and equipment for processing additive manufacturing signals using an image method.

[0005] According to the present invention, an online nondestructive testing method and device for processing additive manufacturing signals using an image method are provided, and the scheme is as follows:

[0006] In a first aspect, an online nondestructive testing method for processing additive manufacturing signals using an image method is provided, the method comprising:

[0007] Step S1: Install the detection equipment and adjust the optical path of the detection equipment and the focal length of the lens;

[0008] Step S2: Import the required part CAD file into the program of the testing equipment, set the process parameters required for printing, and start additive manufacturing;

[0009] Step S3: using a controller with a signal acquisition card in the detection device to receive the ultrasonic signal emitted by the laser interferometer, and recording the amplitude value of the ultrasonic surface wave signal once every set time. After each layer is recorded, the controller saves the amplitude value of the surface wave signal collected in this layer as a file until the additive manufacturing is completed;

[0010] Step S4: Process the recorded values ​​of each layer and form an image analysis;

[0011] Step S5: Real-time simulation of the printing layer formation through the processed data to determine the defect type and size.

[0012] Preferably, the detection equipment in step S1 comprises: a pulse laser, a laser interferometer, a first lens, a reflector, a second lens, and a controller with a signal acquisition card; the pulse laser, the laser interferometer, the first lens, the reflector, and the second lens are all installed on a mounting platform, and the mounting platform is installed on a high-energy beam generating device of the additive manufacturing equipment;

[0013] The installation detection equipment comprises:

[0014] The first step is to install the pulse laser and laser interferometer, connect their synchronization interfaces with coaxial cables, and ensure that they are connected to the additive manufacturing equipment;

[0015] The second step is to install lens 1 under the pulse laser and lens 2 in front of the laser interferometer, ensuring the surface finish of lens 1 and lens 2, that is, no obvious scratches to the naked eye;

[0016] The third step is to install the reflector, fix the center of the reflector, and ensure that the mirror can rotate 360 ​​degrees; the pulse laser emitted by the pulse laser is focused onto the substrate through the No. 1 lens, and the pulse laser on the substrate is reflected to the No. 2 lens through the installed reflector; the No. 2 lens focuses the light signal reflected by the reflector into the laser interferometer;

[0017] The fourth step is to connect the other interface of the laser interferometer to the signal acquisition interface of the controller with the signal acquisition card using a coaxial cable.

[0018] Preferably, adjusting the light path in step S1 includes:

[0019] Turn on the pulse laser and adjust the relative position of its laser head on the mounting platform so that the laser emitted by the pulse laser is vertically irradiated on the forming platform of the additive manufacturing equipment;

[0020] Install lens No. 1 on the optical path of the pulse laser so that lens No. 1 is perpendicular to the beam of the pulse laser to form an excitation spot;

[0021] Adjust the position of the reflector to locate the path of the excitation light spot;

[0022] Turn on the laser interferometer and adjust the position of the laser head of the laser interferometer on the mounting platform so that it can receive the excitation light spot;

[0023] Install the second lens on the optical path of the laser interferometer so that the second lens is perpendicular to the light beam of the laser interferometer.

[0024] Preferably, the step S2 comprises:

[0025] The CAD modeling is performed using Solidworks software, and supports are required for complex components;

[0026] The set process parameters include laser power, scanning speed, scanning spacing, layer thickness, wind field size, and substrate preheating temperature;

[0027] During the additive manufacturing process, the substrate is leveled, the scraper is adjusted to spread the powder, and the oxygen content in the forming chamber is ensured to be less than or equal to 1000ppm.

[0028] Preferably, step S3 comprises:

[0029] The controller with the signal acquisition card in the detection equipment receives the ultrasonic surface wave signal given by the laser interferometer, adjusts the gain of the laser interferometer so that the amplitude value of the surface wave signal reaches 70-80% of the full screen, turns on the additive manufacturing equipment to start additive manufacturing, and records the percentage of the ultrasonic surface wave signal amplitude value occupying the full screen every 0.1-1 second during the manufacturing process. After each layer of the additive manufacturing equipment is manufactured, the controller saves the surface wave signal amplitude value collected for this layer as a file until the entire additive manufacturing process is completed;

[0030] When ≥3 consecutive surface wave signals occupy 10-60% of the screen, it is considered that there is a problem with the forming layer;

[0031] Based on the pulse width of <0.25 seconds, the recording time is set to 0.1-1 seconds to capture the shaping effect of a single pulse and the overall shaping effect after multiple pulse scans.

[0032] Preferably, the step S4 imports the recorded values ​​of each layer into MATLAB software for data processing and image analysis, including:

[0033] 1) Use MATLAB software to classify the information of the received surface ultrasonic signals, including thermal sensitivity coefficient, interlayer temperature, and stress distribution;

[0034] 2) Use MATLAB software to process the received surface ultrasonic signals and form a two-dimensional image based on the amplitude of the surface ultrasonic signals of each layer. If there are three or more consecutive amplitudes lower than 10-60% of the full screen in a file, the corresponding layer of the file will be marked as a problematic layer.

[0035] Preferably, the step S5 imports the data processed by MATLAB into Para View analysis software to simulate the printing layer formation in real time, including:

[0036] The thermal sensitivity coefficient, interlayer temperature, and physical parameters of stress distribution of the problematic layer are imported into the Para View analysis software, and the printing process parameters are input to perform real-time forming simulation on the formed layer. The type and size of defects in the layer are further determined based on the simulation results.

[0037] The defect types include: keyhole, lack of fusion, cracks and pores.

[0038] In a second aspect, an online nondestructive testing device is provided, the device comprising: a pulse laser, a laser interferometer, a first lens, a reflector, a second lens, and a controller with a signal acquisition card;

[0039] The pulse laser, laser interferometer, lens No. 1, reflector, and lens No. 2 are all mounted on a mounting platform, and the mounting platform is mounted on a high-energy beam generating device of the additive manufacturing equipment;

[0040] The pulse laser and the laser interferometer are connected to each other's synchronization interface by a coaxial cable and are simultaneously connected to the additive manufacturing equipment;

[0041] The first lens is installed below the pulse laser, and the second lens is installed in front of the laser interferometer;

[0042] The center of the reflector is fixed. When the pulse laser emitted by the pulse laser is focused onto the substrate through the first lens, the pulse laser on the substrate is reflected to the second lens through the reflector. The second lens focuses the light signal reflected by the reflector into the laser interferometer.

[0043] Then, another interface of the laser interferometer is connected to the signal acquisition interface of the controller with the signal acquisition card by using a coaxial cable;

[0044] The laser interferometer transmits the information in the optical signal to the signal acquisition card in the controller for further information processing.

[0045] In a third aspect, a computer-readable storage medium storing a computer program is provided, and when the computer program is executed by a processor, the steps of the online non-destructive testing method for processing additive manufacturing signals using an image method are implemented.

[0046] In a fourth aspect, an electronic device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the computer program is executed by the processor, the steps of the online nondestructive testing method for processing additive manufacturing signals using an image method are implemented.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] The present invention utilizes laser ultrasound and imaging methods to perform online detection of dual-component additive manufacturing. The imaging method can intuitively and quickly display the forming quality during the forming process and identify defects, which can greatly improve the detection efficiency and greatly reduce the cost of subsequent physical detection, thus meeting the real-time requirements of laser additive manufacturing.

[0049] Other beneficial effects of the present invention will be explained in the specific implementation manner through the introduction of specific technical features and technical solutions. Through the introduction of these technical features and technical solutions, those skilled in the art should be able to understand the beneficial technical effects brought about by the technical features and technical solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0051] Figure 1 It is a diagram of the system structure of the present invention;

[0052] Figure 2 This is the distribution diagram of the laser ultrasonic signal collected by the information acquisition card during laser additive manufacturing of GH3536 nickel-based alloy after processing using METLAB. DETAILED DESCRIPTION

[0053] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0054] In order to realize real-time and efficient online quality detection of formed parts in the metal additive manufacturing process, images are used to represent the changes in the amplitude of laser-stimulated ultrasonic surface waves, and timely feedback is given to potential defects and tissue abnormalities in the forming process, so as to realize synchronous detection of part defects in the additive manufacturing process and avoid detection blind spots caused by complex shapes after the parts are manufactured. An embodiment of the present invention provides an online non-destructive detection method for processing additive manufacturing signals using an image method, with reference to Figure 1 As shown, the method specifically includes:

[0055] Step S1: Install the detection equipment, and adjust the optical path of the detection equipment and the focal length of the lens.

[0056] The detection equipment in this step includes: a pulse laser, a laser interferometer, a lens No. 1, a reflector, a lens No. 2, and a controller with a signal acquisition card; the pulse laser, the laser interferometer, the lens No. 1, the reflector, and the lens No. 2 are all installed on a mounting platform, and the mounting platform is installed on a high-energy beam generating device of the additive manufacturing equipment;

[0057] Installation and testing equipment includes:

[0058] The first step is to install the pulse laser and laser interferometer, connect their synchronization interfaces with coaxial cables, and ensure that they are connected to the additive manufacturing equipment;

[0059] The second step is to install lens 1 under the pulse laser and lens 2 in front of the laser interferometer, ensuring the surface finish of lens 1 and lens 2, that is, no obvious scratches to the naked eye;

[0060] The third step is to install the reflector, fix the center of the reflector, and ensure that the mirror can rotate 360 ​​degrees; the pulse laser emitted by the pulse laser is focused onto the substrate through the No. 1 lens, and the pulse laser on the substrate is reflected to the No. 2 lens through the installed reflector; the No. 2 lens focuses the light signal reflected by the reflector into the laser interferometer;

[0061] The fourth step is to connect the other interface of the laser interferometer to the signal acquisition interface of the controller with the signal acquisition card using a coaxial cable.

[0062] Among them, adjusting the optical path includes:

[0063] Turn on the pulse laser and adjust the relative position of its laser head on the mounting platform so that the laser emitted by the pulse laser is vertically irradiated on the forming platform of the additive manufacturing equipment;

[0064] Install lens No. 1 on the optical path of the pulse laser so that lens No. 1 is perpendicular to the beam of the pulse laser to form an excitation spot;

[0065] Adjust the position of the reflector to locate the path of the excitation light spot;

[0066] Turn on the laser interferometer and adjust the position of the laser head of the laser interferometer on the mounting platform so that it can receive the excitation light spot;

[0067] Install the second lens on the optical path of the laser interferometer so that the second lens is perpendicular to the light beam of the laser interferometer.

[0068] Step S2: Import the required part CAD file into the program of the testing equipment, set the process parameters required for printing, and start additive manufacturing.

[0069] CAD modeling uses Solidworks software for modeling, and supports are required for complex components;

[0070] The set process parameters include laser power, scanning speed, scanning spacing, layer thickness, wind field size, and substrate preheating temperature;

[0071] During the additive manufacturing process, the substrate is leveled, the scraper is adjusted to spread the powder, and the oxygen content in the forming chamber is ensured to be less than or equal to 1000ppm.

[0072] Step S3: Use the controller with a signal acquisition card in the detection equipment to receive the ultrasonic signal emitted by the laser interferometer, and record the amplitude value of the ultrasonic surface wave signal once every set time. After each layer is recorded, the controller saves the amplitude value of the surface wave signal collected in this layer as a file until the additive manufacturing is completed.

[0073] This step specifically includes: a controller with a signal acquisition card in the detection device receives an ultrasonic surface wave signal given by a laser interferometer, adjusts the gain of the laser interferometer so that the amplitude value of the surface wave signal reaches 70-80% of the full screen, turns on the additive manufacturing device to start additive manufacturing, and records the percentage of the ultrasonic surface wave signal amplitude value occupying the full screen every 0.1-1 seconds during the manufacturing process. After each layer of the additive manufacturing device is manufactured, the controller saves the surface wave signal amplitude value collected for this layer as a file until the entire additive manufacturing process is completed;

[0074] When ≥3 consecutive surface wave signals occupy 10-60% of the screen, it is considered that there is a problem with the forming layer;

[0075] Based on the pulse width of <0.25 seconds, the recording time is set to 0.1-1 seconds to capture the shaping effect of a single pulse and the overall shaping effect after multiple pulse scans.

[0076] Step S4: import the recorded values ​​of each layer into MATLAB software for data processing and image analysis;

[0077] 1) Use MATLAB software to classify the information of the received surface ultrasonic signals, including thermal sensitivity coefficient, interlayer temperature, and stress distribution;

[0078] 2) Use MATLAB software to process the received surface ultrasonic signals and form a two-dimensional image based on the amplitude of the surface ultrasonic signals of each layer. If there are three or more consecutive amplitudes lower than 10-60% of the full screen in a file, the corresponding layer of the file will be marked as a problematic layer.

[0079] Step S5: Import the data processed by MATLAB into Para View analysis software to simulate the printing layer formation in real time, including:

[0080] The thermal sensitivity coefficient, interlayer temperature, and physical parameters of stress distribution of the problematic layer are imported into the Para View analysis software, and the printing process parameters are input to perform real-time forming simulation on the formed layer. The type and size of defects in the layer are further determined based on the simulation results. The defect types include keyholes, unfused layers, cracks, and pores.

[0081] The present invention also provides an online nondestructive testing device, which specifically includes: a pulse laser, a laser interferometer, a first lens, a reflector, a second lens, and a controller with a signal acquisition card;

[0082] The pulse laser, laser interferometer, lens No. 1, reflector, and lens No. 2 are all mounted on a mounting platform, and the mounting platform is mounted on a high-energy beam generating device of the additive manufacturing equipment;

[0083] The pulse laser and laser interferometer are connected by a coaxial cable to the synchronization interface of the two and connected to the additive manufacturing equipment at the same time;

[0084] Lens No. 1 is installed below the pulse laser, and lens No. 2 is installed in front of the laser interferometer;

[0085] The center of the reflector is fixed. When the pulse laser emitted by the pulse laser is focused onto the substrate through the first lens, the pulse laser on the substrate is reflected to the second lens through the reflector. The second lens focuses the light signal reflected by the reflector into the laser interferometer.

[0086] Then, another interface of the laser interferometer is connected to the signal acquisition interface of the controller with the signal acquisition card by using a coaxial cable;

[0087] The laser interferometer transmits the information in the optical signal to the signal acquisition card in the controller for further information processing.

[0088] Next, the present invention will be described in more detail.

[0089] The present invention provides an online nondestructive testing method for processing additive manufacturing signals using an image method, referring to Figure 1 As shown, the method specifically includes the following contents:

[0090] Step 1: Install the equipment, adjust the optical path, and adjust the focal length of lens 1 and lens 2.

[0091] The equipment includes: pulse laser, laser interferometer, lens No. 1, reflector, lens No. 2, and computer with signal acquisition card.

[0092] Pulse laser: A laser with a single laser pulse width of less than 0.25 seconds and working only once at a certain interval. It is used to provide high-power laser beams.

[0093] Laser interferometer: An instrument that uses laser beams for interference experiments and measurements. It uses the coherence and monochromaticity of lasers to achieve high-precision measurements of material surface morphology, optical films, optical components, etc. through the interference phenomenon of light.

[0094] Lens No. 1: Convex lens, used to focus the pulsed laser onto the substrate.

[0095] Reflector: A plane mirror used to reflect the pulse signal during the additive manufacturing process to the second lens.

[0096] Lens No. 2: Convex lens, used to focus the light signal reflected by the reflector into the laser interferometer.

[0097] Computer with signal acquisition card: The laser interferometer transmits the information in the optical signal to the signal acquisition card in the computer for further information processing.

[0098] Equipment installation steps: First, install the laser head of the pulse laser, the laser head of the laser interferometer, lens No. 1, reflector, and lens No. 2 at the corresponding positions on the installation platform, connect the synchronization interface of the pulse laser and the synchronization interface of the laser interferometer with a coaxial cable, and then use the coaxial cable to connect the synchronization interface and signal output interface of the laser interferometer to the synchronization interface and signal input interface of the computer with a signal acquisition card, respectively, and install the installation platform on the high-energy beam generating device of the additive manufacturing equipment.

[0099] Adjust the optical path: The optical path is the path of the laser beam signal during the entire additive manufacturing process. Adjust the laser head of the pulse laser and the focal length of the first lens at the same time so that the pulse laser beam can be focused on the forming platform; adjust the angle of the plane mirror to reflect the laser signal during the forming process; and adjust the laser head of the laser interferometer and the focal length of the second lens at the same time so that the laser signal is focused on the laser interferometer.

[0100] Focal lengths of lens No. 1 and lens No. 2: the distance between lens No. 1 and the working platform of the additive manufacturing equipment is the focal length of the first lens; the distance between lens No. 2 and the working platform of the additive manufacturing equipment is the focal length of the second lens.

[0101] Step 2: Import the CAD file of the part to be formed into the program of the corresponding equipment, set the process parameters required for printing, and start additive manufacturing.

[0102] Step 3: Use the signal acquisition card to receive the ultrasonic signal given by the laser interferometer, and record the amplitude value of the ultrasonic surface wave signal every 0.1-1 second. After each layer is recorded, the computer saves the amplitude value of the surface wave signal collected in this layer as a file (named layer1) until the additive manufacturing process is completed.

[0103] Step 4: Import the recorded values ​​of each layer into MATLAB software for data processing and image analysis.

[0104] Step 5: Import the data processed by MATLAB into the Para View analysis software to simulate the printing layer formation in real time and determine the defect type and size.

[0105] Specifically, the equipment installation in step 1 includes: the first step is to install the pulse laser and the laser interferometer, connect the synchronization interface of the two with a coaxial cable, and ensure that they are connected to the printing device (the power-on state is normal); the second step is to install lens No. 1 under the pulse laser and lens No. 2 in front of the laser interferometer, and ensure the surface finish of lens No. 1 and lens No. 2 (no obvious scratches to the naked eye); the third step is to install the reflector, fix the center of the reflector with bolts, and ensure that the mirror can rotate 360°; the fourth step is to connect the other interface of the laser interferometer to the signal acquisition interface of the computer with a signal acquisition card with a coaxial cable.

[0106] Adjust the optical path: turn on the pulse laser, adjust the relative position of its laser head on the mounting platform, so that the laser emitted by the pulse laser is vertically irradiated on the forming platform of the additive manufacturing equipment; install lens No. 1 on the optical path of the pulse laser, so that lens No. 1 is perpendicular to the beam of the pulse laser to form an excitation spot; adjust the position of the reflector to locate the path through which the excitation spot passes; turn on the laser interferometer, adjust the position of the laser head of the laser interferometer on the mounting platform, so that it can receive the excitation spot; install lens No. 2 on the optical path of the laser interferometer, so that lens No. 2 is perpendicular to the beam of the laser interferometer.

[0107] Step 2 includes:

[0108] CAD modeling: Use Solidworks software for modeling. For complex components, it is necessary to consider adding supports.

[0109] Process parameters: including laser power, scanning speed, scanning spacing, layer thickness, wind field size, substrate preheating temperature. The above process parameters need to be investigated separately for different alloys, for example:

[0110] (1) Nickel-based alloy: laser power (200-250 W), scanning speed (1100-1200 mm / s), scanning spacing (0.06-0.08 mm), layer thickness (0.03-0.04 mm), wind field (0.1-0.5), substrate preheating temperature (80 °C).

[0111] (2) Stainless steel: laser power (300-400 W), scanning speed (800-900 mm / s), scanning spacing (0.1-0.12 mm), layer thickness (0.04-0.05 mm), wind field (0.1-1), substrate preheating temperature (100-200 °C).

[0112] Additive manufacturing: level the substrate, adjust the scraper to spread the powder, and ensure that the oxygen content in the forming chamber is less than or equal to 1000ppm.

[0113] Debugging the scraper powder spreading: ensuring that the amount of powder spread at different positions on the substrate is uniform during the printing process, avoiding forming defects and uneven forming structures caused by different amounts of powder spread;

[0114] Oxygen content in the forming chamber: Alloy materials are easily oxidized. Before printing begins, nitrogen / argon gas is introduced into the additive manufacturing equipment to reduce the oxygen content in the forming chamber. An oxygen content below 1000ppm is considered suitable for printing.

[0115] Step 3 includes:

[0116] A computer with a signal acquisition card is used to receive the ultrasonic surface wave signal given by the laser interferometer, and the gain of the laser interferometer is adjusted to make the surface wave signal amplitude reach 70-80% of the full screen. The additive manufacturing equipment is turned on to start additive manufacturing. During the manufacturing process, the percentage of the ultrasonic surface wave signal amplitude value occupying the full screen is recorded every 0.1-1 second. After the additive manufacturing equipment completes each layer, the computer saves the surface wave signal amplitude value collected for this layer as a file until the entire additive manufacturing process is completed.

[0117] When multiple continuous surface wave signals (≥3) occupy 10-60% of the screen, it is considered that there is a problematic forming layer.

[0118] Based on the pulse width (<0.25 seconds), the recording time should capture the shaping effect of a single pulse as much as possible and the overall shaping effect after multiple pulse scans. The recording time is set to 0.1-1 second.

[0119] Step 4 includes:

[0120] MATLAB software is used to classify the information of the received surface ultrasonic signals, including thermal sensitivity coefficient, interlayer temperature, and stress distribution.

[0121] The received surface ultrasonic signals are processed using MATLAB software, and a two-dimensional image is formed according to the amplitude of the surface ultrasonic signals of each layer. If three or more consecutive amplitudes in a file are lower than 10-60% of the full screen, the corresponding layer of the file will be marked as a problematic layer.

[0122] Step 5 includes:

[0123] The thermal sensitivity coefficient, interlayer temperature, and physical parameters of stress distribution of the problematic layer are imported into the Para View analysis software, and the printing process parameters are input to perform real-time forming simulation on the forming layer. The type and size of defects in the layer are further determined based on the simulation results. Defect types include: keyholes (large holes), unfused (irregular defects with powder inside), cracks (irregular strips), and pores (small holes).

[0124] Detection of defect size: Based on the amplitude of the ultrasonic signal of the problematic layer, the higher the ultrasonic signal amplitude, the larger the defect size.

[0125] Determination of defect type: Based on the physical parameters of the thermal sensitivity coefficient (K), interlayer temperature (T), and stress distribution (S) of the problematic layer, the real-time simulation results of the Para View analysis software can be used to observe the defects that are likely to occur in the problematic layer: (1) The thermal sensitivity coefficient is too high (K>10), the local stress value is too large (S>e 3 MPa) will lead to the formation of cracks, which appear as irregular strips; (2) the interlayer temperature is too high (T>500℃), which will cause the solidification speed of the layer to be faster (>10 4 K / s), the evaporated part of the material does not have time to solidify and forms large-sized holes, namely keyholes. The size range of keyholes is 100-1000μm; (3) The interlayer temperature is in a certain range (200-500℃) to form small-sized holes, namely pores. The size of the pores is less than 100μm; (4) The interlayer temperature is too low (<100℃), which will make the heat input of the layer insufficient, resulting in incomplete melting of the powder and the formation of unfused defects. Unfused defects have no clear size range and are characterized by irregular defect morphology and residual powder particles inside the defect.

[0126] Reference Figure 2 As shown in the figure, the laser ultrasonic signal collected by the information acquisition card during the laser additive manufacturing of GH3536 nickel-based alloy is processed into a distribution diagram using METLAB. It can be seen that during the additive manufacturing process, due to the high-power laser beam (>300W), the maximum intensity of the characteristic spectral line collected is 5.6×10 4 At high-intensity amplitude positions (>2×10 4 counts) can form defects due to heat concentration.

[0127] The embodiment of the present invention provides an online nondestructive testing method and device for processing additive manufacturing signals using an imaging method. The imaging method is used to effectively display defects in the forming process online, reduce subsequent testing costs, and quickly optimize forming parameters, thereby improving the efficiency of additive manufacturing and laying a technical foundation for the widespread use of metal additive manufacturing.

[0128] Those skilled in the art know that, in addition to realizing the system and its various devices, modules, and units provided by the present invention in a purely computer-readable program code, it is entirely possible to realize the same functions in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system and its various devices, modules, and units provided by the present invention can be considered as a hardware component, and the devices, modules, and units included therein for realizing various functions can also be regarded as structures within the hardware component; the devices, modules, and units for realizing various functions can also be regarded as both software modules for realizing the method and structures within the hardware component.

[0129] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. An online nondestructive testing method for processing additive manufacturing signals using an image method, characterized in that: include: Step S1: Install the detection equipment and adjust the optical path of the detection equipment and the focal length of the lens; Step S2: Import the required part CAD file into the program of the testing equipment, set the process parameters required for printing, and start additive manufacturing; Step S3: using a controller with a signal acquisition card in the detection device to receive the ultrasonic signal emitted by the laser interferometer, and recording the amplitude value of the ultrasonic surface wave signal once every set time. After each layer is recorded, the controller saves the amplitude value of the surface wave signal collected in this layer as a file until the additive manufacturing is completed; Step S4: Process the recorded values ​​of each layer and form an image analysis; Step S5: Real-time simulation of the printing layer formation through the processed data to determine the defect type and size.

2. The online nondestructive testing method for processing additive manufacturing signals using an image method according to claim 1, characterized in that: The detection equipment in step S1 includes: a pulse laser, a laser interferometer, a first lens, a reflector, a second lens, and a controller with a signal acquisition card; the pulse laser, the laser interferometer, the first lens, the reflector, and the second lens are all installed on a mounting platform, and the mounting platform is installed on a high-energy beam generating device of an additive manufacturing device; The installation detection equipment comprises: The first step is to install the pulse laser and laser interferometer, connect their synchronization interfaces with coaxial cables, and ensure that they are connected to the additive manufacturing equipment; The second step is to install lens 1 under the pulse laser and lens 2 in front of the laser interferometer, ensuring the surface finish of lens 1 and lens 2, that is, no obvious scratches to the naked eye; The third step is to install the reflector, fix the center of the reflector, and ensure that the mirror can rotate 360 ​​degrees; the pulse laser emitted by the pulse laser is focused onto the substrate through the No. 1 lens, and the pulse laser on the substrate is reflected to the No. 2 lens through the installed reflector; the No. 2 lens focuses the light signal reflected by the reflector into the laser interferometer; The fourth step is to connect the other interface of the laser interferometer to the signal acquisition interface of the controller with the signal acquisition card using a coaxial cable.

3. The online nondestructive testing method for processing additive manufacturing signals using an image method according to claim 2, characterized in that: The step S1 of adjusting the light path includes: Turn on the pulse laser and adjust the relative position of its laser head on the mounting platform so that the laser emitted by the pulse laser is vertically irradiated on the forming platform of the additive manufacturing equipment; Install lens No. 1 on the optical path of the pulse laser so that lens No. 1 is perpendicular to the beam of the pulse laser to form an excitation spot; Adjust the position of the reflector to locate the path of the excitation light spot; Turn on the laser interferometer and adjust the position of the laser head of the laser interferometer on the mounting platform so that it can receive the excitation light spot; Install the second lens on the optical path of the laser interferometer so that the second lens is perpendicular to the light beam of the laser interferometer.

4. The online nondestructive testing method for processing additive manufacturing signals using an image method according to claim 1, characterized in that: The step S2 comprises: The CAD modeling is performed using Solidworks software, and supports are required for complex components; The set process parameters include laser power, scanning speed, scanning spacing, layer thickness, wind field size, and substrate preheating temperature; During the additive manufacturing process, the substrate is leveled, the scraper is adjusted to spread the powder, and the oxygen content in the forming chamber is ensured to be less than or equal to 1000ppm.

5. The online nondestructive testing method for processing additive manufacturing signals using an image method according to claim 1, characterized in that: The step S3 comprises: The controller with the signal acquisition card in the detection equipment receives the ultrasonic surface wave signal given by the laser interferometer, adjusts the gain of the laser interferometer so that the amplitude value of the surface wave signal reaches 70-80% of the full screen, turns on the additive manufacturing equipment to start additive manufacturing, and records the percentage of the ultrasonic surface wave signal amplitude value occupying the full screen every 0.1-1 second during the manufacturing process. After each layer of the additive manufacturing equipment is manufactured, the controller saves the surface wave signal amplitude value collected for this layer as a file until the entire additive manufacturing process is completed; When ≥3 consecutive surface wave signals occupy 10-60% of the screen, it is considered that there is a problem with the forming layer; Based on the pulse width of <0.25 seconds, the recording time is set to 0.1-1 seconds to capture the shaping effect of a single pulse and the overall shaping effect after multiple pulse scans.

6. The online nondestructive testing method for processing additive manufacturing signals using an image method according to claim 1, characterized in that: The step S4 imports the recorded values ​​of each layer into MATLAB software for data processing and image analysis, including: 1) Use MATLAB software to classify the information of the received surface ultrasonic signals, including thermal sensitivity coefficient, interlayer temperature, and stress distribution; 2) Use MATLAB software to process the received surface ultrasonic signals and form a two-dimensional image based on the amplitude of the surface ultrasonic signals of each layer. If there are three or more consecutive amplitudes lower than 10-60% of the full screen in a file, the corresponding layer of the file will be marked as a problematic layer.

7. The online nondestructive testing method for processing additive manufacturing signals using an image method according to claim 6, characterized in that: The step S5 imports the data processed by MATLAB into the Para View analysis software to simulate the printing layer formation in real time, including: The thermal sensitivity coefficient, interlayer temperature, and physical parameters of stress distribution of the problematic layer are imported into the Para View analysis software, and the printing process parameters are input to perform real-time forming simulation on the formed layer. The type and size of defects in the layer are further determined based on the simulation results. The defect types include: keyhole, lack of fusion, cracks and pores.

8. An online non-destructive testing device, based on the online non-destructive testing method for processing additive manufacturing signals using an image method according to any one of claims 1 to 7, characterized in that: include: Pulse laser, laser interferometer, lens No. 1, reflector, lens No. 2, and controller with signal acquisition card; The pulse laser, laser interferometer, lens No. 1, reflector, and lens No. 2 are all mounted on a mounting platform, and the mounting platform is mounted on a high-energy beam generating device of the additive manufacturing equipment; The pulse laser and the laser interferometer are connected to each other's synchronization interface by a coaxial cable and are simultaneously connected to the additive manufacturing equipment; The first lens is installed below the pulse laser, and the second lens is installed in front of the laser interferometer; The center of the reflector is fixed. When the pulse laser emitted by the pulse laser is focused onto the substrate through the first lens, the pulse laser on the substrate is reflected to the second lens through the reflector. The second lens focuses the light signal reflected by the reflector into the laser interferometer. Then, another interface of the laser interferometer is connected to the signal acquisition interface of the controller with the signal acquisition card by using a coaxial cable; The laser interferometer transmits the information in the optical signal to the signal acquisition card in the controller for further information processing.

9. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the online non-destructive testing method for processing additive manufacturing signals using an image method according to any one of claims 1 to 7 are implemented.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the computer program is executed by a processor, the steps of the online non-destructive testing method for processing additive manufacturing signals using an image method according to any one of claims 1 to 7 are implemented.

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