Multi-field fusion monitoring external power modulation pulse laser dynamic shaping method

Abstract

The application discloses a kind of external power modulation pulse laser dynamic shaping methods of multi-field fusion monitoring, comprising: real-time acquisition thermal state information, molten pool dynamic information and shaping geometric information, after time synchronization, space registration, feature extraction and weighted fusion, construct multi-field fusion state index;According to the comparison between multi-field fusion state index and preset multi-dimensional joint determination condition, the forming state type of current scanning path section is determined;According to the forming state type, match target pulse time waveform and waveform parameters from candidate pulse waveform library, generate external power modulation signal and time sequence synchronization with scanning control signal, modulate the corresponding modulation laser output of continuous laser;In the process of continuous scanning, according to the forming state type change, dynamically correct or switch external power modulation signal, realize the multi-scale pulse time waveform dynamic regulation and control of scanning path section.The application can improve the stability and quality consistency of forming.

Description

Technical Field

[0001] This invention relates to the field of laser additive manufacturing technology, and in particular to a method for dynamic shaping of externally power modulated pulsed lasers with multi-field fusion monitoring. Background Technology

[0002] Laser Powder Bed Fusion (LPBF) is a typical laser additive manufacturing process that uses a high-energy laser beam to melt metal powder layer by layer along a preset scanning path, and then deposits the powder to form a three-dimensional metal component. This technology offers advantages such as high degree of freedom in forming and high material utilization, and has been widely applied in aerospace, mold manufacturing, medical implants, energy equipment, and the manufacturing of high-performance complex components.

[0003] In existing metal laser powder bed melting processes, continuous fiber lasers are commonly used as the laser heat source. During the forming process, parameters such as laser power, scanning speed, scanning spacing, layer thickness, and scanning strategy are typically used to control the molten pool state and part quality. However, for complex metal components, there are significant differences in the geometric characteristics and heat dissipation conditions between different structural regions. For example, bulk-filled regions have a large solid volume and a relatively continuous heat conduction path, and can usually withstand relatively high heat input; thin-walled regions have a small local cross-sectional area and low equivalent heat capacity, making them prone to local overheating, excessive wall thickness, and deformation; overhanging regions lack solid metal support below, and heat is mainly conducted through the powder layer or local connection areas, resulting in poor heat dissipation capacity and making them prone to molten pool collapse, slag adhesion, increased roughness, and warping; lattice rods and lattice nodes have small geometric dimensions, short scanning paths, and many path intersections, making them prone to heat accumulation, rod diameter deviation, and node overheating; the top surface regions of inner holes and inner flow channels often have similar thermal boundary conditions to overhanging structures, making them prone to powder adhesion, hole diameter deviation, and local collapse.

[0004] In existing technologies, some methods improve local forming quality by changing the laser power, scanning speed, or scanning path in different regions. For example, for overhanging regions, the laser power can be reduced or the scanning speed adjusted; for contour regions, contour scanning parameters can be used to improve dimensional accuracy; and for block regions, energy input can be increased to ensure forming efficiency. These methods belong to static or quasi-static process parameter allocation approaches. While they can improve the average heat input in different regions to some extent, they are difficult to control the change in laser power over short timescales. Therefore, their ability to control the molten pool heating rate, cooling interval, instantaneous thermal shock, and local heat accumulation remains limited.

[0005] On the other hand, pulsed or modulated lasers can adjust the instantaneous heat input of the molten pool by changing parameters such as peak power, average power, pulse frequency, duty cycle, pulse width, rise time, fall time, and pulse interval. Different pulse waveforms, such as square waves, sine waves, triangular waves, trapezoidal waves, rising waves, falling waves, double pulse waves, and multi-pulse waves, can create different heat input rhythms, thereby affecting the molten pool temperature field, flow behavior, solidification rate, spatter behavior, and defect formation. However, in existing metal additive manufacturing processes, pulse waveforms are often used as fixed parameters for forming entire layers or entire components, lacking control methods for dynamic matching and real-time switching based on different structural regions of complex components. Furthermore, allocating parameters only according to predefined shape regions is difficult to adapt to the state changes caused by interlayer thermal history, local remelting, powder spread fluctuations, and changes in scanning sequence during the actual printing process.

[0006] Furthermore, while using a dedicated pulsed laser can directly obtain pulsed output, the equipment is expensive and requires high system compatibility, making it difficult to perform low-cost retrofits on existing continuous laser powder bed melting equipment. However, if the external power modulation interface of the continuous laser can be used to output modulated laser with a preset time waveform via an external power modulation signal, then dynamic output of various pulse time waveforms can be achieved without replacing the dedicated pulsed laser.

[0007] Therefore, LPBF technology urgently needs a dynamic forming method that can determine the current forming state in real time based on online multi-field monitoring results and automatically match the pulse time waveform according to heat flow distribution, molten pool state, and forming risk. This method can dynamically correct the external power modulation signal of the continuous laser within the same layer based on real-time changes in stable melting state, incomplete fusion state, heat accumulation or overheating risk state, molten pool dynamic instability state, and forming geometric deviation state, thereby improving the forming stability and quality consistency of complex metal components. Summary of the Invention

[0008] To address the technical problems existing in the prior art, this invention proposes a multi-field fusion monitoring method for dynamic forming of external power modulated pulsed lasers. This method aims to solve problems such as local overheating, insufficient fusion, dimensional deviations, slag buildup, collapse, splashing, and porosity caused by using uniform laser parameters in different regions of complex components during the existing metal laser powder bed melting process.

[0009] On the one hand, to achieve the above objectives, the present invention provides a method for dynamic shaping of externally power-modulated pulsed lasers with multi-field fusion monitoring, comprising: Obtain the three-dimensional model data of the metal component to be formed, and generate scanning path planning information based on the three-dimensional model data; During the laser scanning forming process, online monitoring information at the current scanning position is collected in real time, and the online monitoring information is synchronized in time and registered in space to construct a multi-field fusion state index for the current scanning path segment; The forming state type of the current scanning path segment is determined by comparing the multi-field fusion state index with the preset multi-dimensional joint judgment conditions. Based on the forming state type, the target pulse time waveform and its waveform parameters are matched from the candidate pulse waveform library to generate waveform control instructions; An external power modulation signal is generated according to the waveform control command, and the output power of the continuous laser is modulated by the external power modulation signal to output a modulated laser with the target pulse time waveform; During continuous scanning, the external power modulation signal is dynamically corrected or switched according to the real-time changes in the forming state type, so that the external power modulation signal is synchronized with the scanning control signal, thereby realizing dynamic forming control of the pulse laser time waveform.

[0010] Preferably, the multi-field fusion state index of the current scan path segment is constructed, including: Real-time acquisition of thermal state information, molten pool dynamic information, and forming geometry information at the current scanning position, and time synchronization and spatial registration of the thermal state information, molten pool dynamic information, and forming geometry information; The thermal state information, molten pool dynamic information, and forming geometry information after time synchronization and spatial registration are respectively processed by feature extraction and normalization, and then weighted and fused to construct the multi-field fusion state index of the current scanning path segment.

[0011] Preferably, the thermal state information includes one or more of infrared thermometry signals, pyrometer signals, thermal radiation intensity signals, and interlayer temperature recording signals, and the extracted thermal state features include one or more of peak temperature, temperature gradient, interlayer temperature, cooling rate, and thermal cycling history. The molten pool dynamic information includes one or more of the following: coaxial high-speed camera images, photodetector signals, rangefinder camera images, plume signals, and spatter signals. The extracted molten pool dynamic features include one or more of the following: molten pool length, molten pool width, molten pool area, wake length, boundary fluctuation amplitude, number of spatters, and plume intensity. The forming geometry information includes one or more of the following: online profilometer signal, visual measurement signal, layer image, and melt channel geometry detection signal. The extracted forming geometry features include one or more of the following: melt channel width, melt channel height, melt channel continuity, edge deviation, local protrusion, and local collapse.

[0012] Preferably, constructing the multi-field fusion state index includes: For thei Each scan path segment is used to calculate the multi-field fusion state index. : ; In the formula, For the first Multi-field fusion state index of each scan path segment; These are normalized values ​​representing the thermal state characteristics. This represents the normalized value of the dynamic characteristics of the molten pool. This represents the normalized value of the forming geometric deviation characteristics; , , All are weighting coefficients.

[0013] Preferably, the preset multi-dimensional joint determination conditions include: Set the first threshold for the fusion state index Second threshold , where 0.25≤ ≤0.45, 0.50≤ ≤0.75; Set the lower threshold for thermal state characteristics and upper limit threshold Dynamic lower limit threshold of molten pool and upper limit threshold Forming geometric deviation threshold ; Where, 0.20≤ ≤0.35, 0.65≤ ≤0.85, 0.20≤ ≤0.35, 0.65≤ ≤0.85, 0.50≤ ≤0.75.

[0014] Preferably, the forming state type includes: when ,and , , When the melting point is reached, it is determined to be in a stable melting state; when ,or When the continuity of the melt channel decreases, it is determined to be an insufficient fusion state; when ,or And accompanied by When the temperature rises, it is determined to be a state of heat accumulation or overheating risk. when When the molten pool exhibits enhanced spatter, enhanced plasma plume, or enhanced molten pool boundary fluctuations, it is determined to be in a state of dynamic instability of the molten pool. when When the defects are accompanied by deviations in the width of the melt channel, edge protrusions, local collapse, or increased dimensional deviations, they are judged to be in a state of forming geometric deviation.

[0015] Preferably, matching the target pulse time waveform and its waveform parameters from the candidate pulse waveform library to generate waveform control commands includes: For the stable melting state, the current pulse time waveform and parameters are matched and maintained; For the insufficient fusion state, a pulse time waveform that increases the effective heat input is matched. The method of increasing the effective heat input includes increasing the peak power, increasing the duty cycle, shortening the pulse interval time, switching to a high duty cycle square wave, trapezoidal wave, or near-continuous waveform at least one. For the aforementioned heat accumulation or overheating risk state, a pulse time waveform is matched to reduce the average heat input or increase the cooling interval. The methods of reducing the average heat input or increasing the cooling interval include reducing the duty cycle, extending the pulse interval time, reducing the peak power, or switching to at least one of a sine wave, a triangle wave, a drooping wave, or a rising-drooping wave. For the dynamic instability state of the molten pool, the pulse time waveform of the smooth power change is matched and smoothed. The smooth power change includes at least one of the following: extending the rise time, extending the fall time, switching to a sine wave, a trapezoidal wave, or a gradually rising and falling wave. For the forming geometric deviation state, the corresponding pulse time waveform is matched according to the deviation direction and the waveform parameters are corrected. The waveform parameters include at least one of peak power, duty cycle, and pulse interval time.

[0016] Preferably, when the forming state type is insufficient fusion state and the modulated pulsed laser still cannot eliminate insufficient fusion, it further includes: reducing the scanning speed of the subsequent adjacent scanning path segments of the current scanning path segment, or performing local compensation scanning on the forming abnormal area after the current layer scanning is completed. When the forming state type is a heat accumulation or overheating risk state and the heat accumulation continues to increase, the method further includes: increasing the scanning speed of the subsequent adjacent scanning path segments of the current scanning path segment.

[0017] On the other hand, to achieve the above objectives, the present invention also provides an external power modulation pulsed laser dynamic shaping system with multi-field fusion monitoring, comprising: The model processing module is used to acquire the 3D model data of the metal component to be formed, perform slicing processing, and generate scanning path planning information. The multi-field online monitoring module is used to collect thermal state information, molten pool dynamic information, and forming geometry information at the current scanning position in real time; The fusion determination module is used to perform time synchronization, spatial registration, feature extraction and normalization processing on the thermal state information, molten pool dynamic information and forming geometry information, weighted fusion to construct a multi-field fusion state index, and determine the forming state type of the current scanning path segment based on the multi-field fusion state index and the preset multi-dimensional joint determination conditions. The waveform matching module is used to match the target pulse time waveform and waveform parameters from the candidate pulse waveform library according to the forming state type, and generate waveform control instructions; An external power modulation module is used to generate an external power modulation signal according to the waveform control command, and modulate the output power of the continuous laser. A synchronization control module is used to keep the external power modulation signal synchronized with the scanning control signal; The scanning shaping module is used to control the continuous laser to output modulated laser with a target pulse time waveform according to the synchronized scanning control signal and the external power modulation signal, and to perform scanning shaping.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects: (1) Realize the fusion analysis of multi-source monitoring information, and match the laser pulse waveform in real time according to the forming state to realize the dynamic control of energy input, thereby improving forming stability, forming quality and dimensional accuracy.

[0019] (2) The continuous laser pulsed method is achieved by using external power modulation, which can be directly integrated into the existing continuous laser additive manufacturing equipment. It has the advantages of simple equipment modification, strong compatibility and low cost, and is easy to promote and apply in engineering.

[0020] (3) The pulse frequency, duty cycle, peak power and waveform characteristics can be adjusted according to different material systems, structural characteristics and forming requirements to achieve flexible control of laser energy input.

[0021] (4) Based on the forming state feedback, the laser waveform and process parameters are adaptively adjusted, reducing manual experimentation and parameter optimization processes and improving process development efficiency. Attached Figure Description

[0022] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a flowchart of an external power-modulated pulsed laser dynamic shaping method for multi-field fusion monitoring according to an embodiment of the present invention; Figure 2This is a schematic diagram of a lightweight metal support component for aviation according to an embodiment of the present invention, wherein 1 is a mounting base, 2 is a connecting hole, 3 is a double-ear connecting plate, 4 is an inclined load-bearing arm, 5 is a thin-walled reinforcing rib, and 6 is a dot matrix weight reduction zone. Detailed Implementation

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] It should be noted that, Figure 1 The flowchart shown illustrates the overall control logic of this invention. Online monitoring, status determination, pulse waveform matching, external power modulation, and scan synchronization are executed according to their respective logical dependencies. For independent data acquisition, feature extraction, and status update processes, they can be executed in parallel or cyclically depending on the system configuration.

[0025] This embodiment proposes a method for dynamic shaping of externally power-modulated pulsed lasers with multi-field fusion monitoring, including: Obtain the three-dimensional model data of the metal component to be formed, and generate scanning path planning information based on the three-dimensional model data; During the laser scanning forming process, online monitoring information at the current scanning position is collected in real time, and the online monitoring information is synchronized in time and registered in space to construct a multi-field fusion state index for the current scanning path segment; The forming state type of the current scanning path segment is determined by comparing the multi-field fusion state index with the preset multi-dimensional joint judgment conditions. Based on the forming state type, the target pulse time waveform and its waveform parameters are matched from the candidate pulse waveform library to generate waveform control instructions; An external power modulation signal is generated according to the waveform control command, and the output power of the continuous laser is modulated by the external power modulation signal to output a modulated laser with the target pulse time waveform; During continuous scanning, the external power modulation signal is dynamically corrected or switched according to the real-time changes in the forming state type, so that the external power modulation signal is synchronized with the scanning control signal, thereby realizing dynamic forming control of the pulse laser time waveform.

[0026] Specifically, such as Figure 1 ,include: S1. Obtain or create a three-dimensional model of the metal component to be formed, and slice the three-dimensional model to obtain the slice outline, scanning path, scanning vector start and end coordinates and scanning timing information of each layer; S2. During the scanning process of metal additive manufacturing, three types of online monitoring information of the current forming area are collected, the online monitoring information is fused and analyzed to obtain the forming state characteristics of the current forming area, and the forming risk type of the current forming area is determined based on the forming state characteristics. S3. Based on the type of forming risk, automatically match the corresponding pulsed laser time waveform and its waveform parameters from the candidate pulse time waveform library, and generate waveform control instructions; S4. Generate an external power modulation signal according to the waveform control command, modulate the output power of the continuous laser, and make the output of the continuous laser match the current forming state of the modulated laser. S5. During the scanning process, the external power modulation signal is corrected or switched in real time according to the changes in the forming state characteristics and the forming risk type, and the external power modulation signal is synchronized with the scanning control signal, thereby realizing the dynamic forming control of the pulse laser time waveform.

[0027] Furthermore, a multi-field fusion state index is constructed for the current scan path segment, including: Real-time acquisition of thermal state information, molten pool dynamic information, and forming geometry information at the current scanning position, and time synchronization and spatial registration of the thermal state information, molten pool dynamic information, and forming geometry information; The thermal state information, molten pool dynamic information, and forming geometry information after time synchronization and spatial registration are respectively processed by feature extraction and normalization, and then weighted and fused to construct the multi-field fusion state index of the current scanning path segment.

[0028] Specifically, as shown in Table 1, the thermal state information includes one or more of infrared thermometry signals, pyrometer signals, thermal radiation intensity signals and interlayer temperature recording signals, and the extracted thermal state features include one or more of peak temperature, temperature gradient, interlayer temperature, cooling rate and thermal cycle history. The molten pool dynamic information includes one or more of the following: coaxial high-speed camera images, photodetector signals, rangefinder camera images, plume signals, and spatter signals. The extracted molten pool dynamic features include one or more of the following: molten pool length, molten pool width, molten pool area, wake length, boundary fluctuation amplitude, number of spatters, and plume intensity. The forming geometry information includes one or more of the following: online profilometer signal, visual measurement signal, layer image, and melt channel geometry detection signal. The extracted forming geometry features include one or more of the following: melt channel width, melt channel height, melt channel continuity, edge deviation, local protrusion, and local collapse.

[0029] Table 1 Furthermore, the multi-field fusion state index is constructed, including: For thei Each scan path segment is used to calculate the multi-field fusion state index. : ; In the formula, For the first Multi-field fusion state index of each scan path segment; These are normalized values ​​representing the thermal state characteristics. This represents the normalized value of the dynamic characteristics of the molten pool. This represents the normalized value of the forming geometric deviation characteristics; , , All are weighting coefficients.

[0030] Furthermore, the preset multi-dimensional joint determination conditions include: Set the first threshold for the fusion state index Second threshold , where 0.25≤ ≤0.45, 0.50≤ ≤0.75; Set the lower threshold for thermal state characteristics and upper limit threshold Dynamic lower limit threshold of molten pool and upper limit threshold Forming geometric deviation threshold ; Where, 0.20≤ ≤0.35, 0.65≤ ≤0.85, 0.20≤ ≤0.35, 0.65≤ ≤0.85, 0.50≤ ≤0.75.

[0031] Furthermore, after fusing and analyzing the online monitoring information, the forming state characteristics are determined according to the following criteria: when ,and , , When the melting point is reached, it is determined to be in a stable melting state; when ,or When the continuity of the melt channel decreases, it is determined to be an insufficient fusion state; when ,or And accompanied by When the temperature rises, it is determined to be a state of heat accumulation or overheating risk. when When the molten pool exhibits enhanced spatter, enhanced plasma plume, or enhanced molten pool boundary fluctuations, it is determined to be in a state of dynamic instability of the molten pool. when When the defects are accompanied by deviations in the width of the melt channel, edge protrusions, local collapse, or increased dimensional deviations, they are judged to be in a state of forming geometric deviation.

[0032] Further, as shown in Table 2, the target pulse time waveform and its waveform parameters are matched from the candidate pulse waveform library to generate waveform control commands, including: For the stable melting state, the current pulse time waveform and parameters are matched and maintained; For the insufficient fusion state, a pulse time waveform that increases the effective heat input is matched. The method of increasing the effective heat input includes increasing the peak power, increasing the duty cycle, shortening the pulse interval time, switching to a high duty cycle square wave, trapezoidal wave, or near-continuous waveform at least one. For the aforementioned heat accumulation or overheating risk state, a pulse time waveform is matched to reduce the average heat input or increase the cooling interval. The methods of reducing the average heat input or increasing the cooling interval include reducing the duty cycle, extending the pulse interval time, reducing the peak power, or switching to at least one of a sine wave, a triangle wave, a drooping wave, or a rising-drooping wave. For the dynamic instability state of the molten pool, the pulse time waveform of the smooth power change is matched and smoothed. The smooth power change includes at least one of the following: extending the rise time, extending the fall time, switching to a sine wave, a trapezoidal wave, or a gradually rising and falling wave. For the forming geometric deviation state, the corresponding pulse time waveform is matched according to the deviation direction and the waveform parameters are corrected. The waveform parameters include at least one of peak power, duty cycle, and pulse interval time.

[0033] Table 2 Furthermore, when the forming state type is insufficient fusion state and the modulated pulsed laser still cannot eliminate insufficient fusion, it also includes: reducing the scanning speed of the subsequent adjacent scanning path segments of the current scanning path segment, or performing local compensation scanning on the forming abnormal area after the current layer scanning is completed. When the forming state type is a heat accumulation or overheating risk state and the heat accumulation continues to increase, the method further includes: increasing the scanning speed of the subsequent adjacent scanning path segments of the current scanning path segment.

[0034] This embodiment also provides an external power-modulated pulsed laser dynamic shaping system with multi-field fusion monitoring, including: The model processing module is used to acquire the 3D model data of the metal component to be formed, perform slicing processing, and generate scanning path planning information. The multi-field online monitoring module is used to collect thermal state information, molten pool dynamic information, and forming geometry information at the current scanning position in real time; The fusion determination module is used to perform time synchronization, spatial registration, feature extraction and normalization processing on the thermal state information, molten pool dynamic information and forming geometry information, weighted fusion to construct a multi-field fusion state index, and determine the forming state type of the current scanning path segment based on the multi-field fusion state index and the preset multi-dimensional joint determination conditions. The waveform matching module is used to match the target pulse time waveform and waveform parameters from the candidate pulse waveform library according to the forming state type, and generate waveform control instructions; An external power modulation module is used to generate an external power modulation signal according to the waveform control command, and modulate the output power of the continuous laser. A synchronization control module is used to keep the external power modulation signal synchronized with the scanning control signal; The scanning shaping module is used to control the continuous laser to output modulated laser with a target pulse time waveform according to the synchronized scanning control signal and the external power modulation signal, and to perform scanning shaping.

[0035] To more clearly illustrate the technical solution of the present invention, specific embodiments are provided below for description: This embodiment employs laser powder bed melting technology, using Ti-6Al-4V titanium alloy powder as the forming material. The Ti-6Al-4V titanium alloy powder is atomized spherical powder with a particle size of 15–53 μm and a sphericity greater than 0.90. The forming process is carried out under a high-purity argon protective atmosphere, with the oxygen content in the forming chamber controlled at a low level to reduce the risk of oxidation and nitriding of the titanium alloy powder during laser melting. The forming equipment uses a continuous fiber laser as the heat source, with a laser wavelength of 1064 nm, a spot diameter of 70 μm, a layer thickness of 40 μm, a scanning interval of 100 μm, and a substrate preheating temperature of 80°C. An external power modulation module controls the continuous laser to output different pulse duration waveforms.

[0036] like Figure 2As shown, this embodiment uses aerospace lightweight metal support components as a typical complex metal component. This component includes a mounting base 1, connecting holes 2, double-ear connecting plates 3, inclined load-bearing arms 4, thin-walled reinforcing ribs 5, and a lattice weight-reduction zone 6. The mounting base 1 and connecting holes 2 simulate the connection area between the aerospace support component and the external assembly structure; the double-ear connecting plates 3 simulate pin connections, bolt connections, or other assembly connection positions; the inclined load-bearing arms 4 simulate the main load-bearing structure in the load transfer path; the thin-walled reinforcing ribs 5 improve the local structural stiffness and characterize the low-heat-capacity thin-walled region; the lattice weight-reduction zone 6 is located within the local weight-reduction area enclosed by the double-ear connecting plates 3, the inclined load-bearing arms 4, or the thin-walled reinforcing ribs 5, and is used to reduce the component's mass while ensuring structural support capacity.

[0037] In this embodiment, the overall envelope size of the test component is 80mm × 55mm × 45mm. The thickness of the mounting base 1 is 6mm, and the connecting holes 2 are distributed at the mounting base 1 and the double-ear connecting plate 3; the inclined load-bearing arm 4 extends from the mounting base 1 towards the double-ear connecting plate 3, with a maximum span of 48mm; the thin-walled reinforcing rib 5 is disposed between the mounting base 1, the double-ear connecting plate 3 and the inclined load-bearing arm 4, with a thickness of 3mm; the single projected area of ​​the lattice weight reduction zone 6 is approximately 22mm × 18mm, and its interior is provided with a rhomboid lattice structure composed of two sets of intersecting inclined rods, with an equivalent width of 0.6mm for the rods.

[0038] Before forming, the control system reads the current layer scan path file to obtain the scan vector start point, end point, scan direction, scan speed, and scan timing. This scan path information is primarily used for spatial positioning of monitoring signals and waveform switching synchronization. During forming, the multi-field online monitoring module collects thermal state information, molten pool dynamic information, and forming geometry information in real time. The fusion determination module performs time synchronization and spatial registration of the above information, unifying signals with different sampling frequencies to the coordinate system of the current scan path segment, and calculates the multi-field fusion state index. In this embodiment, take =0.40、 =0.35、 =0.25. Take... =0.35、 =0.60、 =0.30、 =0.75、 =0.30、 =0.75、 =0.60.

[0039] when < ,and , , When the pulse time is reached, it is determined to be in a stable melting state, and the control system keeps the current pulse time waveform and its parameters unchanged.

[0040] when ,or When the continuity of the melt channel decreases, it is determined to be an insufficient fusion state. At this time, the control system increases the peak power by 10-20W, increases the duty cycle by 5%-10%, shortens the pulse interval by 2-8μs, or switches the current waveform to a high duty cycle square wave, trapezoidal wave, or near-continuous waveform to increase the effective heat input and melt depth. If the insufficient fusion state is still not eliminated, the scanning speed of the subsequent adjacent scanning path segment can be reduced by 5%-10%, or a local compensation scan can be performed on the abnormal area after the current layer scan is completed.

[0041] when ,or And accompanied by When the temperature rises, it is determined to be a state of heat accumulation or overheating risk. At this time, the control system first reduces the duty cycle by 5%–15%, extends the pulse interval time by 3–10μs, or switches the current waveform to a sine wave, triangle wave, drooping wave, or rising-drooping wave to increase the cooling interval and reduce the average heat input per unit time. When the heat accumulation continues to increase, the peak power is further reduced by 10–20W, or the scanning speed of the subsequent adjacent scanning path segment is increased by 5%–10%.

[0042] when When the molten pool is in a state of dynamic instability, accompanied by increased spatter, increased plasma plume, or increased molten pool boundary fluctuations, the control system reduces the power change rate, extends the rise or fall time by 5–20 μs, or switches the current waveform to a sine wave, trapezoidal wave, or gradually rising and falling wave to reduce peak power abrupt changes and molten pool fluctuations.

[0043] when When defects are accompanied by variations in melt channel width, edge protrusion, localized collapse, or increased dimensional deviation, they are identified as forming geometric deviations. If the melt channel is too narrow or discontinuous, the control system increases the effective heat input; if the melt channel is too wide, edge protrusion, or localized collapse, the control system decreases the effective heat input and extends the pulse interval. The corrected parameters are preferentially applied to subsequent adjacent scanning path segments or the corresponding positions in the next layer.

[0044] To verify the forming effect of this embodiment, Comparative Example 1 is set up.

[0045] Comparative Example 1 uses the same materials, component sizes, and slice parameters, but employs a fixed high duty cycle square wave for full-area scanning, without multi-field fusion online monitoring or dynamic switching of pulse time waveforms.

[0046] After forming, a 3D contour scanner is used to measure the sag at the end and transition position of the inclined support arm 4, and to measure the dimensional deviation of the contour edge of the connecting hole 2 and the double-ear connecting plate 3; metallographic image analysis or industrial CT is used to statistically analyze the equivalent rod width, porosity and local defects of the lattice or truss members in the lattice weight reduction zone 6; the Archimedes method or image method is used to determine the relative density of the solid areas such as the mounting base 1 and the double-ear connecting plate 3.

[0047] The test results show that in Comparative Example 1, the average forming thickness of the thin-walled reinforcing rib 5 is 3.16 mm, the thickness deviation is +0.16 mm, the maximum sag in the free extension area of ​​the inclined load-bearing arm 4 is 0.42 mm, the average equivalent rod width of the lattice or truss members in the lattice weight reduction zone 6 is 0.78 mm, the porosity of the process defects in the lattice weight reduction zone 6 is 2.8%, the maximum contour deviation of the contour area of ​​the connecting hole 2 and the double-ear connecting plate 3 is 0.15 mm, and obvious rounding and local overmelting phenomena appear at the edge of the hole and the edge of the double-ear connecting plate 3. After adopting the dynamic control method of this embodiment, the average forming thickness of the thin-walled reinforcing rib 5 is reduced to 3.02 mm, the thickness deviation is reduced to +0.02 mm, the maximum sag at the end of the inclined load-bearing arm 4 is reduced to 0.16 mm, the average equivalent rod width of the lattice or truss members in the lattice weight reduction zone 6 is reduced to 0.63 mm, the porosity of the process defects at the members and connections in the lattice weight reduction zone 6 is reduced to 0.9%, the maximum contour deviation of the contour area of ​​the connecting hole 2 and the double-ear connecting plate 3 is reduced to 0.05 mm, the hole edge and the contour of the double-ear connecting plate 3 remain relatively clear, and the edge over-melting phenomenon is significantly reduced. At the same time, the relative density of the solid areas such as the mounting base 1 and the double-ear connecting plate 3 is increased from 99.1% to 99.3%, indicating that this technical solution can improve the dimensional accuracy, local stability and forming consistency of complex components such as Ti-6Al-4V titanium alloy lightweight lattice brackets in different forming states through multi-field fusion online monitoring and real-time control of external power modulation waveforms.

[0048] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for dynamic shaping of externally powered modulated pulsed lasers based on multi-field fusion monitoring, characterized in that, include: Obtain the three-dimensional model data of the metal component to be formed, and generate scanning path planning information based on the three-dimensional model data; During the laser scanning forming process, online monitoring information at the current scanning position is collected in real time, and the online monitoring information is synchronized in time and registered in space to construct a multi-field fusion state index for the current scanning path segment; The forming state type of the current scanning path segment is determined by comparing the multi-field fusion state index with the preset multi-dimensional joint judgment conditions. Based on the forming state type, the target pulse time waveform and its waveform parameters are matched from the candidate pulse waveform library to generate waveform control instructions; An external power modulation signal is generated according to the waveform control command, and the output power of the continuous laser is modulated by the external power modulation signal to output a modulated laser with the target pulse time waveform; During continuous scanning, the external power modulation signal is dynamically corrected or switched according to the real-time changes in the forming state type, so that the external power modulation signal is synchronized with the scanning control signal, thereby realizing dynamic forming control of the pulse laser time waveform.

2. The method for dynamic shaping of external power-modulated pulsed lasers with multi-field fusion monitoring according to claim 1, characterized in that, Construct the multi-field fusion state index for the current scan path segment, including: Real-time acquisition of thermal state information, molten pool dynamic information, and forming geometry information at the current scanning position, and time synchronization and spatial registration of the thermal state information, molten pool dynamic information, and forming geometry information; The thermal state information, molten pool dynamic information, and forming geometry information after time synchronization and spatial registration are respectively processed by feature extraction and normalization, and then weighted and fused to construct the multi-field fusion state index of the current scanning path segment.

3. The method for dynamic shaping of external power-modulated pulsed lasers with multi-field fusion monitoring according to claim 2, characterized in that, The thermal state information includes one or more of infrared thermometry signals, pyrometer signals, thermal radiation intensity signals, and interlayer temperature recording signals. The extracted thermal state features include one or more of peak temperature, temperature gradient, interlayer temperature, cooling rate, and thermal cycling history. The molten pool dynamic information includes one or more of the following: coaxial high-speed camera images, photodetector signals, rangefinder camera images, plume signals, and spatter signals. The extracted molten pool dynamic features include one or more of the following: molten pool length, molten pool width, molten pool area, wake length, boundary fluctuation amplitude, number of spatters, and plume intensity. The forming geometry information includes one or more of the following: online profilometer signal, visual measurement signal, layer image, and melt channel geometry detection signal. The extracted forming geometry features include one or more of the following: melt channel width, melt channel height, melt channel continuity, edge deviation, local protrusion, and local collapse.

4. The method for dynamic shaping of external power-modulated pulsed lasers with multi-field fusion monitoring according to claim 2, characterized in that, Constructing the multi-field fusion state index includes: For the first i Each scan path segment is used to calculate the multi-field fusion state index. : ； In the formula, For the first Multi-field fusion state index of each scan path segment; These are normalized values ​​representing the thermal state characteristics. This represents the normalized value of the dynamic characteristics of the molten pool. This represents the normalized value of the forming geometric deviation characteristics; , , All are weighting coefficients.

5. The method for dynamic shaping of external power-modulated pulsed lasers with multi-field fusion monitoring according to claim 4, characterized in that, The preset multi-dimensional joint judgment conditions include: Set the first threshold for the fusion state index Second threshold , where 0.25≤ ≤0.45, 0.50≤ ≤0.75; Set the lower threshold for thermal state characteristics and upper limit threshold Dynamic lower limit threshold of molten pool and upper limit threshold Forming geometric deviation threshold ; Where, 0.20≤ ≤0.35, 0.65≤ ≤0.85, 0.20≤ ≤0.35, 0.65≤ ≤0.85, 0.50≤ ≤0.

75.

6. The method for dynamic shaping of external power-modulated pulsed lasers with multi-field fusion monitoring according to claim 5, characterized in that, The forming state types include: when ,and , , When the melting point is reached, it is determined to be in a stable melting state; when ,or When the continuity of the melt channel decreases, it is determined to be an insufficient fusion state; when ,or And accompanied by When the temperature rises, it is determined to be a state of heat accumulation or overheating risk. when When the molten pool exhibits enhanced spatter, enhanced plasma plume, or enhanced molten pool boundary fluctuations, it is determined to be in a state of dynamic instability of the molten pool. when When the defects are accompanied by deviations in the width of the melt channel, edge protrusions, local collapse, or increased dimensional deviations, they are judged to be in a state of forming geometric deviation.

7. The method for dynamic shaping of external power-modulated pulsed lasers with multi-field fusion monitoring according to claim 6, characterized in that, Match the target pulse time waveform and its waveform parameters from the candidate pulse waveform library to generate waveform control commands, including: For the stable melting state, the current pulse time waveform and parameters are matched and maintained; For the insufficient fusion state, a pulse time waveform that increases the effective heat input is matched. The method of increasing the effective heat input includes increasing the peak power, increasing the duty cycle, shortening the pulse interval time, switching to a high duty cycle square wave, trapezoidal wave, or near-continuous waveform at least one. For the aforementioned heat accumulation or overheating risk state, a pulse time waveform is matched to reduce the average heat input or increase the cooling interval. The methods of reducing the average heat input or increasing the cooling interval include reducing the duty cycle, extending the pulse interval time, reducing the peak power, or switching to at least one of a sine wave, a triangle wave, a drooping wave, or a rising-drooping wave. For the dynamic instability state of the molten pool, the pulse time waveform of the smooth power change is matched and smoothed. The smooth power change includes at least one of the following: extending the rise time, extending the fall time, switching to a sine wave, a trapezoidal wave, or a gradually rising and falling wave. For the forming geometric deviation state, the corresponding pulse time waveform is matched according to the deviation direction and the waveform parameters are corrected. The waveform parameters include at least one of peak power, duty cycle, and pulse interval time.

8. The method for dynamic shaping of external power-modulated pulsed lasers with multi-field fusion monitoring according to claim 1, characterized in that, When the forming state type is insufficient fusion state and the modulated pulsed laser still cannot eliminate insufficient fusion, it also includes: reducing the scanning speed of the subsequent adjacent scanning path segments of the current scanning path segment, or performing local compensation scanning on the forming abnormal area after the current layer scanning is completed. When the forming state type is a heat accumulation or overheating risk state and the heat accumulation continues to increase, the method further includes: increasing the scanning speed of the subsequent adjacent scanning path segments of the current scanning path segment.

9. An external power-modulated pulsed laser dynamic shaping system employing the method described in any one of claims 1-8 with multi-field fusion monitoring, characterized in that, include: The model processing module is used to acquire the 3D model data of the metal component to be formed, perform slicing processing, and generate scanning path planning information. The multi-field online monitoring module is used to collect thermal state information, molten pool dynamic information, and forming geometry information at the current scanning position in real time; The fusion determination module is used to perform time synchronization, spatial registration, feature extraction and normalization processing on the thermal state information, molten pool dynamic information and forming geometry information, weighted fusion to construct a multi-field fusion state index, and determine the forming state type of the current scanning path segment based on the multi-field fusion state index and the preset multi-dimensional joint determination conditions. The waveform matching module is used to match the target pulse time waveform and waveform parameters from the candidate pulse waveform library according to the forming state type, and generate waveform control instructions; An external power modulation module is used to generate an external power modulation signal according to the waveform control command, and modulate the output power of the continuous laser. A synchronization control module is used to keep the external power modulation signal synchronized with the scanning control signal; The scanning shaping module is used to control the continuous laser to output modulated laser with a target pulse time waveform according to the synchronized scanning control signal and the external power modulation signal, and to perform scanning shaping.

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