A method and system for laser additive manufacturing zoned hierarchical dynamic shaping

Abstract

The application discloses a kind of laser additive manufacturing partition grading dynamic forming method and system, by obtaining three-dimensional model and layering, division main area, key area and gradual gradient transition zone;With first layer thick slice, with second layer thick single-time powder laying twice, in sequence scanning key area lower part, main area, transition area and key area upper part;First layer thick is second layer thick twice, main body uses continuous flat top light and first light spot, transition uses quasi-pulse flat top light, first light spot and low-frequency high duty cycle, key uses quasi-pulse flat top light, second light spot and high-frequency low duty cycle;In transition zone, realize smooth transition by multi-stage multi-parameter coordination gradual change, eliminate tissue mutation and parameter step defect, unify efficiency and accuracy.

Description

Technical Field

[0001] The invention relates to the field of metal additive manufacturing technology, specifically to a laser additive manufacturing method and system for partitioned and graded dynamic forming. Background Technology

[0002] Laser powder bed melting technology has been applied in the manufacturing of critical aerospace components. To achieve a balance between efficiency and precision, existing technologies have developed various partitioned and hierarchical manufacturing strategies based on spatial beam mode switching. For example, one known approach is to analyze the component's geometric model to obtain characteristic regions and assign them beam modes with different spatial intensity distributions, such as Gaussian, toroidal, and flat-top beams. However, this approach does not deeply consider the abrupt thermodynamic changes at the transition between regions, and its mode switching is often abrupt or simple spatial light field interpolation, failing to achieve continuous evolution of the molten pool solidification behavior and microstructure. Another approach involves laser remelting of spliced ​​regions, but as a post-processing method, it cannot solve the problem of consistent performance in the transition zone during parallel forming processes. Therefore, existing technologies lack a refined transition strategy with a physical mechanism basis that can ensure seamless microstructure and performance transitions between regions with different beam modes and process parameters. Summary of the Invention

[0003] This invention proposes a laser additive manufacturing method for partitioned and graded dynamic forming, comprising: S1. Obtain the three-dimensional model of the component to be formed, and then divide the three-dimensional model into layers perpendicular to the forming direction to obtain multiple layers; S2. For each layer, identify and delineate the main area, key area, and gradient transition zone between them within that layer. S3. For the slice, the slice is divided into sections with the first layer thickness, and the powder is spread twice with the second layer thickness as the single powder spreading thickness. According to the preset scanning order, the key area, the main area, the transition area and the remaining part of the key area are scanned in sequence. The first layer thickness is twice the second layer thickness. S4. Within the gradient transition zone, a smooth transition between the main area and the key area is achieved through multi-stage, multi-parameter coordinated gradient transition.

[0004] Furthermore, S3 specifically includes: After the first layer of powder is applied, a quasi-pulse flat-top beam is used with a second spot diameter, high frequency and low duty cycle to scan the part of the key area corresponding to the second layer thickness. After the second layer of powder is applied, a continuous flat-top beam is used to scan the part of the main area corresponding to the first layer thickness with the first spot diameter. A quasi-pulse flat-top beam is used to scan the portion of the transition region corresponding to the first layer thickness with a first spot diameter, low frequency, and high duty cycle. A quasi-pulse flat-top beam was used to scan the remaining second layer thickness in the critical area with a second spot diameter, high frequency, and low duty cycle.

[0005] Furthermore, S2 also includes: based on the geometric features of the slice profile and the physical properties of the material to be formed, adaptively calculating and allocating the first spot diameter, the first layer thickness, the second spot diameter, and the second layer thickness through a preset parameter allocation model, wherein the second spot diameter is smaller than the first spot diameter and the second layer thickness is smaller than the first layer thickness.

[0006] Furthermore, the width of the gradient transition zone is determined by the parameter allocation model based on the complexity of the geometric features and material properties within the transition zone.

[0007] Furthermore, the multi-stage, multi-parameter coordinated gradual change includes at least: In the first stage, before the scanning path enters the transition zone, the parameters of the quasi-pulse flat-top beam are gradually adjusted to make its thermodynamic state approach that of the continuous flat-top beam. In the second stage, within the transition zone, at least two parameters among the laser mode, spot diameter, layer thickness, and laser power are simultaneously and continuously changed gradually. In the third stage, after the scanning path enters the main region, all parameters have stabilized at the target values ​​of the main region.

[0008] Furthermore, in the parameter adjustment of the first stage, the pulse frequency of the quasi-pulse flat-top beam is gradually reduced and its duty cycle is increased until it approaches a continuous mode.

[0009] Furthermore, it also includes: within the gradient transition zone, sensors monitor the molten pool parameters in real time and feed the monitoring data back to the control unit to correct the parameter gradient curve and width within the transition zone in real time.

[0010] Furthermore, the peak-to-average power ratio of the quasi-pulse flat-top beam is adjusted in real time by a power modulator to match the gradual change of other parameters within the transition band.

[0011] Furthermore, when the main area is scanned using a continuous flat-top beam, the scanning path adopts an island-shaped partition scanning strategy; when the key area is scanned using a quasi-pulse flat-top beam, the scanning path adopts a contour offset scanning strategy.

[0012] Furthermore, a laser additive manufacturing partitioned and hierarchical dynamic forming system based on gradient transition band co-modulation is proposed, comprising: The model analysis and parameter allocation module is used to acquire the 3D model, layer it, divide it into regions, and allocate parameters for each region based on the model. The beam generation and modulation module is used to generate continuous flat-top beams and quasi-pulse flat-top beams; The path planning module is used to generate the scanning path and the powder spreading order; The gradient transition control module is used to perform multi-stage, multi-parameter coordinated gradient transitions within the gradient transition zone between the main area and the critical area, so as to achieve a smooth transition of beam mode and process parameters.

[0013] This invention proposes a laser additive manufacturing method and system for dynamic forming of partitioned and graded components. By introducing a gradual gradient transition zone and a multi-stage, multi-parameter collaborative gradual change strategy, it fundamentally solves the problem of abrupt changes in microstructure and properties caused by region switching in the prior art, eliminates defects such as microstructure delamination and interface cracks caused by parameter step changes, and ensures a high degree of consistency in microstructure and properties in different regions of the component. Attached Figure Description

[0014] Figure 1 This is a flowchart illustrating a battery swapping service scheduling method proposed in this invention. Figure 2 This is a schematic diagram of the coordinated partitioning and grading printing using continuous and quasi-pulsed lasers. Detailed Implementation

[0015] refer to Figure 1 This invention proposes a laser additive manufacturing method for partitioned and graded dynamic forming, comprising: S1. Obtain the three-dimensional model of the component to be formed, and then divide the three-dimensional model into layers perpendicular to the forming direction to obtain multiple layers.

[0016] The three-dimensional model is a digital representation of the component to be formed; the forming direction is the direction of additive manufacturing deposition; the layer is the two-dimensional cross-sectional profile of the three-dimensional model after discretization and slicing perpendicular to the forming direction. Specifically, the three-dimensional model of the component to be formed is obtained through three-dimensional modeling software or scanning equipment, the forming direction is set as the Z-axis, and the three-dimensional model is sliced ​​and discretized along the Z-axis at a set layer thickness interval to obtain a series of layer data parallel to the XY plane. In a specific implementation scenario, for a titanium alloy aerospace structural component, its CAD three-dimensional model is obtained, the forming direction is set as the height direction of the part, and layer slicing is performed to obtain multiple layer data sequences.

[0017] S2. For each layer, identify and delineate the main region, key region, and gradient transition zone between them within that layer.

[0018] The main region refers to the thicker, simpler structure; the key region refers to the thin-walled, overhanging, and finely textured areas; the gradient transition zone is a spatial buffer zone between the main region and the key region. Specifically, based on the geometric features of the slice outline, wall thickness, curvature, and overhang angle information are extracted. Areas with a wall thickness greater than a set threshold and gentle curvature are designated as the main region, while areas with a wall thickness less than the set threshold and exhibiting overhangs or fine structures are designated as key regions. A gradient transition zone is then defined between the two. In one specific implementation scenario, for a slice layer of the aforementioned titanium alloy aerospace structural component, a 5mm thick, large-volume filling portion is identified as the main region, and a 0.5mm thick reinforcing rib and a 45-degree overhang surface are identified as key regions. A gradient transition zone is then defined at the junction of these two regions.

[0019] S3. For the slice, divide it into slices with the first layer thickness, and apply powder twice with the second layer thickness as the single powder application thickness. According to the preset scanning order, perform partitioned and graded scanning on the key area, the main area, the transition area and the remaining part of the key area in sequence, wherein the first layer thickness is twice the second layer thickness.

[0020] The first layer thickness is the slice thickness of the main area and the transition area; the second layer thickness is the slice thickness of the critical area and the thickness of a single powder application; the two powder applications are the powder application operations required to complete the formation of one first layer thickness; the preset scanning sequence is the sequential scanning execution path set for different areas and their corresponding layer thicknesses. Specifically, perpendicular to the forming direction, the 3D model is sliced ​​according to the first layer thickness, but the powder application system only applies the second layer thickness (i.e., half the first layer thickness) of powder each time, requiring two applications to complete the formation of one complete first layer thickness. Within two powder application cycles, scanning is performed sequentially in the order of the lower part of the critical area, the main area, the transition area, and the upper part of the critical area. In a specific implementation scenario, the first layer thickness H1 is set to 100μm, and the second layer thickness H2 is set to 50μm. After the first 50μm powder layer, a quasi-pulsed flat-top beam is used with a second spot diameter D2 = 100μm, a high frequency (e.g., 5kHz), and a low duty cycle (e.g., 30%) to scan the critical area corresponding to 50μm. After the second 50μm powder layer, a continuous flat-top beam is used with a first spot diameter D1 = 200μm to scan the main area corresponding to 100μm. Then, a quasi-pulsed flat-top beam is used with a first spot diameter D1 = 200μm, a low frequency (e.g., 1kHz), and a high duty cycle (e.g., 80%) to scan the transition area corresponding to 100μm. Finally, a quasi-pulsed flat-top beam is used with a second spot diameter D2 = 100μm, a high frequency (e.g., 5kHz), and a low duty cycle (e.g., 30%) to scan the remaining 50μm of the critical area.

[0021] like Figure 2 As shown, the specific forming process of continuous and quasi-pulse laser co-scanning includes: First, using a quasi-pulse laser with high frequency, low duty cycle, and second spot diameter, after completely laying a second layer of thick powder on the substrate, the key area 1 is printed; Second, using a continuous laser with first spot diameter and second layer thickness, after completely laying a second layer of thick powder again, the main body area is printed; Subsequently, using a parameter combination that transforms from continuous pulse laser to quasi-pulse laser, with low frequency, high duty cycle, first spot diameter, and first layer thickness, the transition area is printed; Finally, using a quasi-pulse laser with high frequency, low duty cycle, second spot diameter, and second layer thickness, the key area 2 is printed.

[0022] The continuous and quasi-pulse laser coordinated scanning is a dynamic execution logic that achieves the partitioning and grading of different regions within a complete first layer thickness forming cycle through the timing coordination of two powder spreading actions and four parameter combinations. The transition refers to the gradual transition of the laser mode from continuous to quasi-pulse in the transition region, accompanied by the coordinated gradual change of multiple parameters such as frequency, duty cycle, spot diameter and layer thickness.

[0023] Specifically, within the first layer thickness forming cycle, the system first completes the fine scanning of the lower part of the key area 1, then completes the efficient scanning of the main body area, then crosses the transition area to complete the smooth transition of parameters, and finally completes the fine scanning of the upper part of the key area 2. The whole process strictly follows the partitioned and hierarchical sequence from the key area to the main body area, then to the transition area, and finally back to the key area.

[0024] In a specific implementation scenario, combined with Figure 2 The collaborative scanning logic shown in the diagram uses a quasi-pulse laser to precisely shape the lower part of the key area 1 after the first powder application, a continuous laser to efficiently shape the main body area after the second powder application, then changes the parameters to print the transition area, and finally uses a quasi-pulse laser to shape the upper part of the key area 2, thus achieving a balance between efficiency and precision.

[0025] In this embodiment, after the first powder coating, a quasi-pulsed flat-top beam is used with a second spot diameter, high frequency, and low duty cycle to scan the portion of the critical region corresponding to the second layer thickness. After the second powder coating, a continuous flat-top beam is used with a first spot diameter to scan the portion of the main region corresponding to the first layer thickness. A quasi-pulsed flat-top beam is used with a first spot diameter, low frequency, and high duty cycle to scan the portion of the transition region corresponding to the first layer thickness. A quasi-pulsed flat-top beam is used with a second spot diameter, high frequency, and low duty cycle to scan the remaining portion of the critical region with the second layer thickness. The high frequency and low duty cycle are pulse parameter combinations used in the critical region to achieve fine thermal cycle control; the low frequency and high duty cycle are pulse parameter combinations used in the transition region to approximate the continuous mode thermodynamic state. Specifically, in the two powder coating cycles, a fine scan is first performed on the lower part of the critical region with a small layer thickness, followed by an efficient scan on the main region with a large layer thickness, then a low-frequency pulse scan is performed on the transition region with a large spot diameter, and finally a fine scan is performed on the upper part of the critical region with a small layer thickness. In one specific implementation scenario, after the first layer of powder is applied, the critical area with a 50μm layer thickness is scanned using a 100μm spot, a 5kHz frequency, and a 30% duty cycle. After the second layer of powder is applied, the main area with a 100μm layer thickness is scanned using a 200μm spot continuous wave, the transition area with a 100μm layer thickness is scanned using a 200μm spot, a 1kHz frequency, and an 80% duty cycle, and the remaining 50μm layer thickness in the critical area is scanned using a 100μm spot, a 5kHz frequency, and a 30% duty cycle.

[0026] S4. Within the gradient transition zone, a smooth transition between the main area and the key area is achieved through multi-stage, multi-parameter coordinated gradient transition.

[0027] The multi-stage, multi-parameter coordinated gradual change is a control strategy that involves phased, synchronous, and continuous gradual changes in multiple parameters, including laser mode, spot diameter, layer thickness, laser power, and pulse parameters, within the transition zone. Specifically, within the gradual gradient transition zone at the boundary between the main region and the critical region, low-frequency pulse modulation is gradually introduced when transitioning from the continuous mode. The pulse frequency linearly increases from 0 to the target value, while the duty cycle gradually decreases from 100% to the target value. Simultaneously, the laser power is finely adjusted to maintain the stability of the molten pool size, ensuring a continuous and smooth spatial change in heat input density. In one specific implementation scenario, a gradual gradient transition zone with a width of 2 mm is set between the main region and the critical region. Starting from the boundary of the main region, within a path of 0 to 2 mm, the pulse frequency linearly changes from 0 to 5 kHz, and the duty cycle linearly changes from 100% to 30%, achieving continuous thermodynamic evolution.

[0028] In a further embodiment, S2 further includes: based on the geometric features of the sheet slice contour and the physical properties of the material to be formed, adaptively calculating and allocating the first spot diameter, the first layer thickness, the second spot diameter, and the second layer thickness through a preset parameter allocation model, wherein the second spot diameter is smaller than the first spot diameter, and the second layer thickness is smaller than the first layer thickness. The parameter allocation model is a calculation model constructed based on the thermal-structural coupling influence coefficient and the material weighting factor, used to automatically match optimal process parameters according to geometric and material properties; the first spot diameter and the first layer thickness are coarse standard parameters for the main region; the second spot diameter and the second layer thickness are fine standard parameters for the critical region. Specifically, the geometric feature vector of the sheet slice contour and the physical properties of the material to be formed are extracted and input into the preset parameter allocation model. The model outputs the first spot diameter (e.g., 200 micrometers) and the first layer thickness (e.g., 100 micrometers) for the main region, and the second spot diameter (e.g., 100 micrometers) and the second layer thickness (e.g., 50 micrometers) for the critical region. In a specific implementation scenario, for titanium alloy materials, the parameter allocation model calculates the first spot diameter D1=200μm and the first layer thickness H1=100μm; for the 0.5 mm thin-walled critical area, the second spot diameter D2=100μm and the second layer thickness H2=50μm are calculated to meet the requirements of fine feature forming.

[0029] The width of the gradient transition zone is determined by the parameter allocation model based on the complexity of the geometric features and material properties within the transition zone. Specifically, the width of the gradient transition zone determines the spatial scale of the parameter gradient. When the transition zone crosses a complex region where thin and thick walls intersect, the parameter allocation model allocates a wider transition zone (e.g., 2 mm) to accommodate a smoother parameter change; when the transition zone is located in a structurally simple region, a narrower transition zone (e.g., 0.5 mm) is allocated. In one specific implementation scenario, when transitioning from a thick-walled body to a critical 0.5 mm thin-walled region, due to the high complexity of the geometric features, the parameter allocation model sets the transition zone width to 2 mm; when transitioning to a structurally simple thick wall, the width is set to 0.5 mm.

[0030] The multi-stage, multi-parameter coordinated gradual change includes at least the following stages: First, before the scanning path enters the transition zone, the parameters of the quasi-pulsed flat-top beam are gradually adjusted to make its thermodynamic state approach that of the continuous flat-top beam; Second, within the transition zone, at least two parameters among the laser mode, spot diameter, layer thickness, and laser power are simultaneously and continuously gradually changed; Third, after the scanning path enters the main region, all parameters are stabilized at the target values ​​of the main region. Specifically, the first stage is a pre-adjustment stage used to change the thermodynamic state of the molten pool in advance; the second stage is a core transition stage, realizing the spatial continuous evolution of the multiphysics field; and the third stage is a stable execution stage. Specifically, the first stage parameter pre-adjustment is initiated before the scanning path leaves the critical region and enters the transition zone; after entering the transition zone, the second stage synchronous gradual change is executed; and after crossing the transition zone and entering the main region, the third stage parameter locking is completed. In one specific implementation scenario, the first stage is initiated 0.5 mm from the boundary of the critical area, reducing the pulse frequency and increasing the duty cycle; after entering the 2 mm wide transition zone, the second stage is executed, synchronously varying the spot diameter and layer thickness; after fully entering the main area, the third stage is executed, with the parameters stabilizing at the parameters of the continuous flat-top beam.

[0031] In the first stage of parameter adjustment, the pulse frequency of the quasi-pulsed flat-top beam is gradually reduced while its duty cycle is increased until it approaches a continuous mode. Gradually reducing the pulse frequency and increasing the duty cycle is an operation that makes the pulse energy input tend to be continuously distributed in the time domain. Specifically, the pulse frequency of the quasi-pulsed flat-top beam is gradually reduced from 5 kHz in a set step size, while the duty cycle is gradually increased from 30%. When the pulse frequency approaches 0 and the duty cycle approaches 100%, the thermodynamic state of the quasi-pulsed flat-top beam approaches that of a continuous flat-top beam. In one specific implementation scenario, within a 0.5 mm travel distance of the first stage path, the pulse frequency is linearly reduced from 5 kHz to 1 kHz, and the duty cycle is linearly increased from 30% to 80%, shortening the single-pulse energy input interval and making the thermal accumulation effect tend to be continuous.

[0032] The method in this embodiment further includes: within the gradient transition zone, monitoring the molten pool parameters in real time using sensors, and feeding the monitoring data back to the control unit to correct the parameter gradient curve and width within the transition zone in real time. The sensors are high-frequency monitoring devices used to acquire molten pool temperature, morphology, and thermal gradient; the control unit is a computational module that executes closed-loop control logic. Specifically, during the transition zone scanning process, the sensors acquire molten pool infrared radiation information and morphological images in real time, extract the molten pool width and peak temperature, and feed them back to the control unit. The control unit compares these values ​​with the target values ​​and dynamically corrects the laser power gradient curve and the actual effective width of the transition zone. In one specific implementation scenario, a coaxial pyrometer detects that the maximum width of the molten pool within the transition zone deviates from the target value by 0.1 mm. After feeding this information back to the control unit, the control unit fine-tunes the laser power gradient rate in real time to bring the molten pool width back within the target range.

[0033] The peak-to-average power ratio (PAPR) of the quasi-pulse flat-top beam is controlled in real time by a power modulator to match the gradual changes in other parameters within the transition band. The PAPR is the ratio of the pulse peak power to the average power, reflecting the degree of energy concentration in the laser time domain. Specifically, during the transition band transition, the spot diameter and layer thickness change. To maintain a constant energy density, the power modulator dynamically adjusts the ratio of the peak power to the average power of the quasi-pulse flat-top beam based on real-time calculated values. In one specific implementation scenario, when the spot diameter gradually decreases from 200 micrometers to 150 micrometers, to ensure that the power density does not jump after the spot size reduction, the power modulator adjusts the PAPR from 0.6 to 0.7 in real time, achieving a smooth transition in thermal input density.

[0034] When the main area is scanned using a continuous flat-top beam, the scanning path employs an island-shaped partitioning scanning strategy; when the key area is scanned using a quasi-pulse flat-top beam, the scanning path employs a contour offset scanning strategy. The island-shaped partitioning scanning strategy divides the scanning area into several square or rectangular sub-regions and scans them sequentially in a random or specific order; the contour offset scanning strategy generates parallel scanning paths by equidistant offsets inward or outward from the contour boundary. Specifically, the main area is divided into multiple square islands, and continuous flat-top beam scanning is performed in a checkerboard jump order; for thin-walled or fine features in the key area, an offset path is generated circle by circle inward from the feature contour as the initial boundary, and a quasi-pulse flat-top beam is used to scan along the offset path. In one specific implementation scenario, a 200-micron spot continuous flat-top beam is used to scan the main area in 5 mm × 5 mm island-shaped partitions; for 0.5 mm thin-walled features, a 100-micron spot quasi-pulse flat-top beam is used to generate a scanning path by offsetting inward from the outer contour, accurately filling the thin-walled area.

[0035] This invention also proposes a laser additive manufacturing partitioned and hierarchical dynamic forming system based on gradient transition band cooperative modulation, comprising: The model analysis and parameter allocation module is used to acquire the 3D model, layer it, divide it into regions, and allocate parameters for each region based on the model. The beam generation and modulation module is used to generate continuous flat-top beams and quasi-pulse flat-top beams; The path planning module is used to generate the scanning path and the powder spreading order; The gradient transition control module is used to perform multi-stage, multi-parameter coordinated gradient transitions within the gradient transition zone between the main area and the critical area, so as to achieve a smooth transition of beam mode and process parameters.

[0036] The model analysis and parameter allocation module is a hardware and software unit that performs 3D data processing, regional feature recognition, and parameter mapping. The beam generation and modulation module is an optomechanical system including a laser, a beam shaper, and a power modulator. The path planning module is an algorithm module that generates scanning trajectory coordinate data and powder laying timing logic. The gradient transition control module is the core controller that coordinates the execution of gradient strategies by the above modules. Specifically, the model analysis and parameter allocation module reads the CAD model and outputs layer data and a list of regional parameters; the beam generation and modulation module outputs a laser beam of the corresponding mode according to the parameter list; the path planning module generates island partitions and contour offset paths, as well as two powder laying instructions; when the path crosses the transition zone, the gradient transition control module synchronously issues instructions to drive the beam generation and modulation module and the galvanometer system to achieve coordinated parameter gradient. In a specific implementation scenario, when the forming system starts working, the model analysis and parameter allocation module outputs the division results and parameters of the main body and key areas of the 100th layer, the path planning module issues the first powder laying command and the scanning path of the lower part of the key area, and the gradient transition control module synchronously controls the beam generation and modulation module to output high-frequency low duty cycle quasi-pulse light; after the second powder laying, the scanning control of the continuous light in the main body area, the low-frequency high duty cycle quasi-pulse light in the transition area and the high-frequency low duty cycle quasi-pulse light in the upper part of the key area are executed in sequence.

[0037] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A laser additive manufacturing method for partitioned and graded dynamic forming, characterized in that, include: S1. Obtain the three-dimensional model of the component to be formed, and then divide the three-dimensional model into layers perpendicular to the forming direction to obtain multiple layers; S2. For each layer, identify and delineate the main area, key area, and gradient transition zone between them within that layer. S3. For the slice, the slice is divided into sections with the first layer thickness, and the powder is spread twice with the second layer thickness as the single powder spreading thickness. According to the preset scanning order, the key area, the main area, the transition area and the remaining part of the key area are scanned in sequence. The first layer thickness is twice the second layer thickness. S4. Within the gradient transition zone, a smooth transition between the main area and the key area is achieved through multi-stage, multi-parameter coordinated gradient transition.

2. The laser additive manufacturing method for partitioned and graded dynamic forming as described in claim 1, characterized in that, S3 specifically includes: After the first layer of powder is applied, a quasi-pulse flat-top beam is used with a second spot diameter, high frequency and low duty cycle to scan the part of the key area corresponding to the second layer thickness. After the second layer of powder is applied, a continuous flat-top beam is used to scan the part of the main area corresponding to the first layer thickness with the first spot diameter. A quasi-pulse flat-top beam is used to scan the portion of the transition region corresponding to the first layer thickness with a first spot diameter, low frequency, and high duty cycle. A quasi-pulse flat-top beam was used to scan the remaining second layer thickness in the critical area with a second spot diameter, high frequency, and low duty cycle.

3. The laser additive manufacturing method for partitioned and graded dynamic forming as described in claim 2, characterized in that, S2 further includes: based on the geometric features of the slice profile and the physical properties of the material to be formed, adaptively calculating and allocating the first spot diameter, the first layer thickness, the second spot diameter, and the second layer thickness through a preset parameter allocation model, wherein the second spot diameter is smaller than the first spot diameter and the second layer thickness is smaller than the first layer thickness.

4. The laser additive manufacturing method for partitioned and graded dynamic forming as described in claim 1, characterized in that, The width of the gradient transition zone is determined by the parameter allocation model based on the complexity of the geometric features and material properties within the transition zone.

5. The laser additive manufacturing method for partitioned and graded dynamic forming as described in claim 1, characterized in that, The multi-stage, multi-parameter coordinated gradual change includes at least the following: In the first stage, before the scanning path enters the transition zone, the parameters of the quasi-pulse flat-top beam are gradually adjusted to make its thermodynamic state approach that of the continuous flat-top beam. In the second stage, within the transition zone, at least two parameters among the laser mode, spot diameter, layer thickness, and laser power are simultaneously and continuously changed gradually. In the third stage, after the scanning path enters the main region, all parameters have stabilized at the target values ​​of the main region.

6. The laser additive manufacturing method for partitioned and graded dynamic forming as described in claim 5, characterized in that, In the parameter adjustment of the first stage, the pulse frequency of the quasi-pulse flat-top beam is gradually reduced and its duty cycle is increased until it approaches a continuous mode.

7. The laser additive manufacturing method for partitioned and graded dynamic forming as described in claim 1, characterized in that, Also includes: Within the gradient transition zone, sensors monitor the molten pool parameters in real time and feed the monitoring data back to the control unit to correct the parameter gradient curve and width within the transition zone in real time.

8. The laser additive manufacturing method for partitioned and graded dynamic forming as described in claim 2, characterized in that, The peak-to-average power ratio of the quasi-pulse flat-top beam is controlled in real time by a power modulator to match the gradual change of other parameters in the transition band.

9. The laser additive manufacturing method for partitioned and graded dynamic forming as described in claim 1, characterized in that, When the main area is scanned using a continuous flat-top beam, the scanning path adopts an island-shaped partition scanning strategy; when the key area is scanned using a quasi-pulse flat-top beam, the scanning path adopts a contour offset scanning strategy.

10. A laser additive manufacturing partitioned and graded dynamic forming system based on gradient transition band cooperative modulation, characterized in that, include: The model analysis and parameter allocation module is used to acquire the 3D model, layer it, divide it into regions, and allocate parameters for each region based on the model. The beam generation and modulation module is used to generate continuous flat-top beams and quasi-pulse flat-top beams; The path planning module is used to generate the scanning path and the powder spreading order; The gradient transition control module is used to perform multi-stage, multi-parameter coordinated gradient transitions within the gradient transition zone between the main area and the critical area, so as to achieve a smooth transition of beam mode and process parameters.

Images