Multiband composite laser coaxial wire feeding dissimilar material additive manufacturing system and method

Abstract

The invention belongs to the technical field of laser additive manufacturing, and particularly discloses a multiband composite laser coaxial wire feeding dissimilar material additive manufacturing system and method. Comprising a multi-band laser generation module and a multi-channel wire feeding module which are used for accommodating and conveying at least two or more different metal wires; the multi-band composite laser coaxial processing head is used for coaxially coupling laser beams with different wavelength bands in space to form composite laser and carrying out light-wire coaxial coupling on the composite laser and a conveyed metal wire; the monitoring module is used for collecting images and temperature field data in real time; and the control module is used for dynamically adjusting the power ratio of the laser beams of different wavebands in the multiband laser generation module according to the monitoring data fed back by the monitoring module. A multi-beam multi-band composite laser coupling and double-wire-feeding three-way pipe structure is adopted, and in-situ integrated printing forming of dissimilar materials through a single printing nozzle is achieved.

Description

Technical Field

[0001] This invention belongs to the field of laser additive manufacturing technology, and more specifically, relates to a multi-band composite laser coaxial wire feeding dissimilar material additive manufacturing system and method. Background Technology

[0002] Currently, most mainstream laser additive manufacturing equipment on the market uses a single infrared laser. When printing highly reflective materials such as copper and aluminum, because the material has an extremely low absorption rate of infrared light in its solid state, extremely high laser power is often required to melt the material. However, once the material melts and enters the liquid state, its absorption rate of infrared light will increase dramatically (even by an order of magnitude).

[0003] Existing multi-band composite technologies (such as blue light composite with infrared light) typically employ fixed power ratios for processing. However, this open-loop or semi-open-loop control method cannot adapt to the complex thermal accumulation effects during additive manufacturing. Maintaining high-power blue / green light at all times can easily lead to overheating of the molten pool, vaporization spatter, and even keyhole collapse in the liquid stage; insufficient power can result in incomplete fusion defects. Especially for printing with dissimilar materials, the melting points and absorptivity characteristics of different materials vary greatly, making it difficult to guarantee the quality of the bonding interface using fixed parameter methods.

[0004] Therefore, there is an urgent need for an intelligent additive manufacturing method that can dynamically adjust the energy ratio of different wavebands according to the real-time state of the molten pool and maintain a constant "effective energy absorption". Summary of the Invention

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a multi-band composite laser coaxial wire feeding dissimilar material additive manufacturing system and method. It integrates "multi-band spectral coupling," "coaxial filament delivery," and "closed-loop control of molten pool energy," overcoming the bottleneck of laser absorption rate in highly reflective metals at different phase transition stages through dynamic spectral ratios of red, blue, and green lasers. Combined with a dual-channel coaxial wire feeding structure and an equivalent constant energy control algorithm, it not only achieves in-situ seamless switching printing of dissimilar metals (such as highly reflective metals and ordinary metals) within a single nozzle but also ensures the stability of molten pool energy input during complex phase transition processes. This significantly solves industry problems in existing technologies, such as difficulty in forming highly reflective materials, weak bonding between dissimilar materials, low energy utilization, and numerous spatter defects, greatly expanding the engineering application capabilities of laser additive manufacturing in high-end fields such as aerospace and electronic packaging.

[0006] To achieve the above objectives, according to one aspect of the present invention, a multi-band composite laser coaxial wire feeding dissimilar material additive manufacturing system is proposed, comprising: A multi-band laser generating module for generating laser beams of at least two or more different wavelength bands; A multi-channel wire feeding module for accommodating and conveying at least two or more different metal wires; A multi-band composite laser coaxial processing head is connected to the multi-band laser generating module and the multi-channel wire feeding module. It is used to coaxially couple laser beams of different wavelength bands in space to form a composite laser, and to perform optical-wire coaxial coupling between the composite laser and the conveyed metal wire. The monitoring module is used to acquire real-time image data of the molten pool and temperature field data during the additive manufacturing process; and The control module is used to plan printing parameters based on the metal material model of the component to be printed, and to dynamically adjust the power ratio of different band laser beams in the multi-band laser generation module based on the monitoring data fed back by the monitoring module.

[0007] As a further preferred embodiment, the multi-band laser generating module includes a red laser, a blue laser, and a green laser. The multi-band composite laser coaxial processing head is provided with fiber optic interfaces arranged in a ring array, so that the red, blue, and green light output by the red, blue, and green lasers are uniformly and symmetrically distributed in a ring array in space and focused on the same point.

[0008] As a further preferred embodiment, the multi-channel filament feeding module adopts a dual-filament feeding three-channel structure, which includes a mixing filament tube and at least two independently controlled filament feeding mechanisms. The control module is used to control the alternating operation, filament feeding, and retraction of the filament feeding mechanisms to achieve in-situ switching printing of dissimilar materials within a single printhead.

[0009] As a further preferred embodiment, the wire feeding mechanism is a gear-driven wire feeding mechanism.

[0010] As a further preferred embodiment, a local protective gas module is also included, which includes six protective gas outlets integrated into the multi-band composite laser coaxial processing head, and the six protective gas outlets are arranged in an array with the hybrid wire tube as the center.

[0011] As a further preferred embodiment, the system also includes a water-cooling module comprising multiple individually circulating cooling pipes arranged in a ring array uniformly around the fiber optic interface.

[0012] According to another aspect of the present invention, a method for additive manufacturing of dissimilar materials using multi-band composite laser coaxial wire feeding is also provided, comprising the following steps: Step 1: Plan the printing parameters based on the metal material model of the component to be printed; Step 2: According to the printing parameters, the multi-band laser generating module is controlled to generate at least two single laser beams of different wavelength bands, and the multiple single laser beams are transmitted to the multi-band composite laser coaxial processing head and coaxially coupled in a ring array in space to form a multi-band composite laser. Step 3: Control the multi-channel wire feeding module to select one target wire from at least two types of metal wires and feed it to the central channel of the multi-band composite laser coaxial processing head, so that the target wire is coaxially coupled with the multi-band composite laser. Step four: Use the energy of the multi-band composite laser to melt the target filament, forming a molten pool and a metal deposition layer on the substrate; Step 5: Real-time acquisition of image and temperature data of the molten pool area; the control module adjusts the output parameters of the multi-band laser generating unit based on the feedback data.

[0013] As a further preferred option, step three also includes: According to the slicing path file of the metal material model, when the printing path of the first material ends, the control module controls the wire feeding mechanism corresponding to the first material to reverse and exit the first material. Then, the other wire feeding mechanism rotates forward to transport the second material to the mixing wire tube. At the same time, the control module automatically updates the target effective absorption power and material property database according to the physical properties of the second material.

[0014] As a further preferred option, step five also includes the following steps: (51) Extract the real-time temperature and morphological features of the molten pool based on the image and temperature data of the molten pool area; (52) Determine the physical phase transition stage of the material in the current molten pool based on the extracted temperature and morphological characteristics; (53) Call the preset material property database to determine the theoretical absorption rate of the material for different wavelengths of laser at the current physical phase transition stage and the current temperature; (54) Based on the preset principle of constant effective absorption power of the target, and combined with the theoretical absorption rate, the output power value required for each band of laser is calculated in reverse. (55) Based on the calculated output power value, dynamically adjust the power ratio of the red, blue and green lasers in the multi-band laser generating unit.

[0015] As a further preferred option, in step (55), the dynamic adjustment of the power ratio follows the following strategy: When the material is in the physical phase transition stage of solid-state high reflectivity, the control module increases the weighting factor of short-wavelength laser to make the output power mainly blue or green light, with red light as a supplement or turned off. When the material is in the physical phase transition stage of liquid deep dissolution, the control module decreases the weighting factor of short-wavelength laser to reduce the output power of blue or green light and increase the output power of red light in order to maintain the depth of the molten pool and reduce energy consumption.

[0016] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages: 1. This invention integrates "multi-band spectral coupling", "coaxial filament delivery", and "closed-loop control of molten pool energy". By dynamically matching the spectra of red, blue, and green lasers, it breaks through the bottleneck of laser absorption rate of highly reflective metals at different phase transition stages from a physical mechanism perspective. Combined with a dual-channel coaxial filament feeding structure and an equivalent constant energy control algorithm, it not only realizes in-situ seamless switching printing of dissimilar metals (such as highly reflective metals and ordinary metals) within a single nozzle, but also ensures the stability of molten pool energy input during complex phase transition processes. It significantly solves industry problems such as the difficulty in forming highly reflective materials, weak bonding of dissimilar materials, low energy utilization, and numerous spatter defects in existing technologies, greatly expanding the engineering application capabilities of laser additive manufacturing in high-end fields such as aerospace and electronic packaging.

[0017] 2. In the solid, highly reflective stage, the system automatically allocates a high proportion of short-wavelength laser (blue / green light) to rapidly establish a molten pool, utilizing its high absorption characteristics for materials such as copper and aluminum. This avoids the energy waste caused by the extremely high power required by using infrared light alone. Once the material enters the deep-melting liquid stage, the system automatically reduces the proportion of short-wavelength laser and instead uses red light, which has higher electro-optical conversion efficiency and significantly increased absorption in liquid metal, to maintain the melting depth. This "state-dependent" spectral management significantly reduces overall equipment energy consumption while ensuring forming quality and effectively prevents molten pool vaporization and splashing caused by excess energy in the liquid stage.

[0018] 3. Compared to traditional off-axis filament feeding technology, this invention's annular laser spot ensures uniform heating of the filament in any scanning direction, eliminating the need for frequent nozzle posture adjustments and greatly simplifying path planning, supporting continuous printing of complex spatial trajectories. Simultaneously, the unique dual-channel filament feeding design allows for in-situ switching of different filament types (e.g., from structural steel to conductive copper) based on Gcode instructions during printing. Combined with the control system's adaptive parameter updates for different material physical properties, this achieves high metallurgical quality bonding of dissimilar materials or functionally graded materials (FGM), solving the problem of traditional equipment's difficulty in manufacturing complex multi-material components in a single operation.

[0019] 4. This invention adjusts the output in reverse based on a real-time calculated material absorption rate model to maintain a constant actual energy absorbed by the material per unit time. This effectively overcomes the process instability caused by heat accumulation, wire feeding fluctuations, or batch-to-batch material differences in additive manufacturing. Especially at the moment of switching between dissimilar materials, the system can quickly capture the drastic changes in the molten pool temperature field and automatically smooth the transition of laser ratios, eliminating defects such as incomplete fusion or poor bonding caused by parameter mismatch, and significantly improving the density and mechanical properties of the final formed part. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a multi-band composite laser coaxial wire feeding dissimilar material additive manufacturing system according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the "double wire feeding tee" structure involved in an embodiment of the present invention; Figure 3 This is a top view of the multi-band composite laser coaxial processing head according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the multi-band composite laser coupling and coaxial coupling principle of composite laser and wire involved in the embodiments of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0022] like Figures 1 to 4As shown, the same reference numerals are used to denote the same elements or structures. This embodiment of the invention provides a multi-band composite laser coaxial wire feeding dissimilar material additive manufacturing system. The system includes a computer system 1, red lasers 2 and 5, blue lasers 3 and 6, green lasers 4 and 7, a hybrid filament tube 8, wire feeding mechanisms 82 and 84, metal wires 81 and 83, a local protective gas module 9, a molten pool monitoring camera 10, a forming monitoring camera 11, a thermal imaging camera 12, a metal deposition layer 13, a printing substrate 14, a printing platform X / Y / Z motion mechanism 15, a multi-band composite laser coaxial processing head 16, a water cooling module 17, and a housing 18. Red laser 2 is connected to red optical fiber 21, red laser 5 is connected to red optical fiber 51, blue laser 3 is connected to blue optical fiber 31, blue laser 6 is connected to blue optical fiber 61, green optical fiber 41 is connected to green laser 4, green optical fiber 71 is connected to green laser 7, and a multi-band composite laser 20 is also present. More specifically, red optical fibers 21 and 51 are connected to red laser 2 and 5 respectively, blue optical fibers 31 and 61 are connected to blue laser 3 and 6 respectively, and green optical fibers 41 and 71 are connected to green laser 4 and 7 respectively. The six multi-band optical fibers are integrated into the multi-band composite laser coaxial processing head 16. Dissimilar metal wires 81 and 83 are fed into the print head through a "dual wire feeding tee" structure via independently controlled gear feeding mechanisms 82 and 84, ensuring that the fed wires are perpendicular to the printing substrate 14. Simultaneously, the motors of gear feeding mechanisms 82 and 84 reverse to extract the dissimilar metal wires 81 and 83. A local protective gas module 9 is also integrated into the multi-band composite laser coaxial processing head 16, providing inert gas protection during metal printing to prevent oxidation of the metal under the high temperature of the laser. The multi-band composite laser coaxial processing head 16 integrates the optical path, gas path, and wire feeding unit into a single unit.

[0023] like Figure 2 As shown, gear wire feeding mechanism 82 independently controls the feeding and unloading of metal wire 81, and gear wire feeding mechanism 84 independently controls the feeding and unloading of metal wire 83. The feeding and unloading of gear wire feeding mechanisms 82 and 84 are controlled separately and independently, and gear wire feeding mechanisms 82 and 84 cannot work simultaneously, forming a "dual wire feeding three-way tube" structure. When printing metal wire 81, the forward rotation of the motor of gear wire feeding mechanism 82 feeds the metal wire 81 into the multi-band composite laser coaxial processing head 16, and the hybrid wire tube 8 is connected to the multi-band composite laser coaxial processing head 16. Once the workpiece area to which the metal wire 81 belongs is printed, the gear wire feeding mechanism 82 reverses to remove the metal wire 81. After the metal wire 81 is removed, the gear wire feeding mechanism 84 starts working. The gear wire feeding mechanism 84 rotates forward to feed the metal wire 83 into the multi-band composite laser coaxial processing head 16, and the metal wire 83 begins to melt and print, thereby realizing the in-situ integrated printing of dissimilar materials with a single printing nozzle.

[0024] like Figure 3 As shown in the top view of the multi-band composite laser coaxial processing head 16, six laser beams are symmetrically distributed in a uniform ring array. At the same time, red optical fibers 21 and 51, blue optical fibers 31 and 61, and green optical fibers 41 and 71 are symmetrically distributed in pairs. With the metal wire 8 as the center, each laser beam is evenly distributed around the metal wire 8, which facilitates the focusing of the six laser beams of different wavelengths to a single point, facilitates the coaxial coupling of the optical fibers, and is beneficial for the laser energy to be focused onto the wire.

[0025] The multi-band composite laser coaxial processing head 16 consists of two red beams, two blue beams, and two green beams coaxially coupled. The red beam wavelength is 900–1100 nm, the blue beam wavelength is 400–500 nm, and the green beam wavelength is 500–550 nm. The maximum power of the laser generated by each red, blue, and green fiber laser module is 2000 W, and all six fiber laser modules can be controlled independently.

[0026] Meanwhile, the local protective gas module 9 adopts a 6-hole vent structure. The 6 protective gas vents are centered on the metal wire 8, and each vent is evenly distributed around the metal wire 8. By increasing the number of vents, the protection area is expanded, which fully and effectively protects the melting and oxidation prevention of the metal. The water-cooling module 17 is symmetrically distributed in space and adopts a single-pipe connection and circulating cooling water method to fully dissipate heat for the multi-band composite laser coaxial processing head 16.

[0027] like Figure 4 As shown, red optical fibers 22 and 52, blue optical fibers 32 and 62, and green optical fibers 42 and 72 are uniformly and symmetrically distributed in a ring array in space. Finally, the six multi-band lasers are coupled to a point to form a multi-band composite laser 20. The multi-band composite laser 20 is coaxially coupled with the metal wire 8. The multi-band composite laser 20 acts on the metal wire 8 to melt highly reflective materials such as copper and aluminum.

[0028] The multi-band composite laser coaxial processing head 16 is fixedly mounted on the top of the housing 18. During the printing process, the multi-band composite laser coaxial processing head 16 remains stationary, while the printing substrate 14 moves under the drive of the X / Y / Z motion mechanism 15 of the printing platform, thereby changing the printing path.

[0029] The system's workflow is as follows: Taking multi-band composite laser coaxial wire feeding additive manufacturing of two dissimilar materials, metal wire 81 (Ф1.2mm GH4169 wire) and metal wire 83 (Ф1.2mm Cu wire), as an example, the process includes the following steps: (1) First, the slicing path is planned for the 3D model of the dissimilar materials. In the area where the GH4169 material is to be printed, the metal wire 81 is fed into the multi-band composite laser coaxial processing head 16 by the forward rotation of the gear wire feeding mechanism 82 motor. The metal wire 81 (Ф1.2mm GH4169 wire) is melted and shaped by the multi-band composite laser coaxial coupling. After the GH4169 material area is printed, the gear wire feeding mechanism 82 motor reverses to remove the metal wire 81 from the multi-band composite laser coaxial processing head 16. The gear wire feeding mechanism 84 starts working. The gear wire feeding mechanism 84 motor rotates forward to feed the metal wire 83 (Ф1.2mm Cu wire) into the multi-band composite laser coaxial processing head 16 to start the printing of the Cu material area, completing the printing of one layer of dissimilar materials. Each layer of printing is repeated in this way to complete the printing of the entire model. The entire model uses zigzag filling paths and generates Gcode code path files.

[0030] (2) Printing parameter settings: The multi-band composite laser 20 is formed by coupling the multi-band composite laser coaxial processing head 16 to print the metal wire 81 (Ф1.2mm GH4169 wire). The parameters are: single beam red light 200W, single beam blue light 200W, single beam green light 200W, total power 1200W, wire feeding speed 16.5mm / s, printing speed 10mm / s, layer height 1.3mm, filling gap 1.2mm, defocusing amount -1mm, protective gas flow rate 20 L / min. The parameters for printing metal wire 83 (Ф1.2mm Cu wire) are: single beam red light 200W, single beam blue light 300W, single beam green light 300W, total power 2000W, wire feed speed 16.5mm / s, printing speed 10mm / s, layer height 1.3mm, fill gap 1.2mm, defocusing amount -1mm, and protective gas flow rate 20 L / min.

[0031] (3) Before additive manufacturing, the surface of the printing substrate 14 is moderately polished and cleaned with alcohol to remove the oxide film or contaminants on its surface.

[0032] (4) Import the slice design parameter file Gcode into the device and control it through the computer system 1. Combine the molten pool monitoring camera 10, the forming monitoring camera 11, and the thermal imaging camera 12 to monitor the forming process of the metal deposition layer 13 in real time and adjust the forming process parameters in a timely manner.

[0033] (5) After the last layer of printing is completed, the printing substrate 14 is removed and cooled. The workpiece is separated from the printing substrate 14 by wire cutting to complete the multi-band composite laser coaxial wire feeding additive manufacturing of two dissimilar materials, metal wire 81 (Ф1.2mm GH4169 wire) and metal wire 83 (Ф1.2mm Cu wire).

[0034] In another embodiment, taking the multi-band composite laser coaxial wire feeding additive manufacturing of highly reflective material 83 metal wire (Ф1.2mm Cu wire) as an example, the system's workflow includes the following steps: (1) First, the slicing path is planned for the three-dimensional model of the high reflectivity material. The entire model adopts the zigzag filling path and generates the Gcode code path file. The "double wire feeding tee" structure only calls the gear wire feeding mechanism 84 to work. The gear wire feeding mechanism 84 motor rotates forward to feed the metal wire 83 (Ф1.2mm Cu wire) into the multi-band composite laser coaxial processing head 16, and melts the metal wire 83 according to the printing path to stack and form the shape.

[0035] (2) Printing parameter settings: A multi-band composite laser 20 is formed by coupling the multi-band composite laser coaxial processing head 16. The parameters for printing metal wire 83 (Ф1.2mm Cu wire) are: single beam red light 0W, single beam blue light 400W, single beam green light 400W, total power 1600W, wire feeding speed 16.5mm / s, printing speed 10mm / s, layer height 1.3mm, filling gap 1.2mm, defocusing amount -1mm, protective gas flow rate 20 L / min.

[0036] (3) Before additive manufacturing, the surface of the printing substrate 14 is moderately polished and cleaned with alcohol to remove the oxide film or contaminants on its surface.

[0037] (4) Import the slice design parameter file Gcode into the device and control it through the computer system 1. Combine the molten pool monitoring camera 10, the forming monitoring camera 11, and the thermal imaging camera 12 to monitor the forming process of the metal deposition layer 13 in real time and adjust the forming process parameters in a timely manner.

[0038] (5) After the last layer of printing is completed, the printing substrate 14 is removed and cooled. The workpiece is separated from the printing substrate 14 by wire cutting to complete the multi-band composite laser coaxial wire feeding additive manufacturing of high reflective material 83 (Ф1.2mm Cu wire).

[0039] In another embodiment, taking the multi-band composite laser coaxial wire feeding additive manufacturing of ordinary material 83 metal wire (Ф1.2mm TC4 wire) as an example, the system's workflow includes the following steps: (1) First, the slicing path is planned for the three-dimensional model of ordinary metal material. The entire model adopts the filling path of zigzag and generates the Gcode code path file. The "double wire feeding tee" structure only calls the gear wire feeding mechanism 84 to work. The gear wire feeding mechanism 84 motor rotates forward to feed the metal wire 83 (Ф1.2mm TC4 wire) into the multi-band composite laser coaxial processing head 16, and melts the metal wire 83 according to the printing path to stack and form the shape.

[0040] (2) Printing parameter settings: A multi-band composite laser 20 is formed by coupling the multi-band composite laser coaxial processing head 16. The parameters for printing the metal wire 83 (Ф1.2mm TC4 wire) are: single beam red light 500W, single beam blue light 0W, single beam green light 0W, total power 1000W, wire feeding speed 14mm / s, printing speed 8mm / s, layer height 1.3mm, filling gap 1.2mm, defocusing amount -1mm, protective gas flow rate 20 L / min.

[0041] (3) Before additive manufacturing, the surface of the printing substrate 14 is moderately polished and cleaned with alcohol to remove the oxide film or contaminants on its surface.

[0042] (4) Import the slice design parameter file Gcode into the device and control it through the computer system 1. Combine the molten pool monitoring camera 10, the forming monitoring camera 11, and the thermal imaging camera 12 to monitor the forming process of the metal deposition layer 13 in real time and adjust the forming process parameters in a timely manner.

[0043] (5) After the last layer of printing is completed, the printing substrate 14 is removed and cooled. The workpiece is separated from the printing substrate 14 by wire cutting to complete the multi-band composite laser coaxial wire feeding additive manufacturing of ordinary metal materials 83 (Ф1.2mm TC4 wire).

[0044] In a preferred embodiment of the present invention, based on the monitoring data from the monitoring module, the control module further integrates a dynamic adjustment method for maintaining the effective absorption power of the additive material, as detailed below: During additive manufacturing, the thermal imaging camera 12 and the molten pool monitoring camera 10 simultaneously acquire visual image data of the molten pool, and the control module processes the acquired image data. More specifically, the monitoring unit uses real-time acquisition of image data and temperature data of the molten pool area and feeds it back to the control module; the control module adjusts the output parameters of the multi-band laser generation module based on the feedback data.

[0045] Based on the above embodiments, the control method of the present invention is implemented based on a multi-band composite laser coaxial wire feeding dissimilar material additive manufacturing system. The system includes a multi-band laser generation module, a multi-channel wire feeding module, a multi-band composite laser coaxial processing head, a monitoring module, and a control module, and includes the following steps: 1. Laser generation step: Control the multi-band laser generation unit to generate at least two single-beam lasers of different wavelength bands; Second, laser coupling step: The single laser beam is transmitted to the multi-band composite laser coaxial processing head and coaxially coupled in a ring array in space to form a multi-band composite laser. Third, wire feeding step: The multi-channel wire feeding unit is controlled to select a target wire from at least two types of metal wires and feed it to the central channel of the multi-band composite laser coaxial processing head, so that the target wire is coaxially coupled with the multi-band composite laser. In this step, the control module controls the wire feeding mechanism corresponding to the first material to reverse and exit the first material when the printing path of the first material ends, according to the slicing path file of the metal material model. Then, the other wire feeding mechanism rotates forward to feed the second material to the hybrid wire tube. At the same time, the control module automatically updates the target effective absorption power and material property database according to the physical properties of the second material.

[0046] Fourth, melting and forming step: using the energy of the multi-band composite laser to melt the target filament, forming a molten pool and a metal deposition layer on the substrate; Fifth, monitoring and feedback steps: The monitoring unit collects image data and temperature data of the molten pool area in real time and feeds them back to the control module; In this step: the monitoring module collects image data and temperature data of the molten pool area in real time, and then the control module extracts the real-time temperature features of the molten pool, including: performing Kalman filtering on the raw temperature data collected by the thermal imaging camera to obtain the estimated temperature; calculating the first derivative of the estimated temperature with time as the heating rate feature; the extraction of the morphological features of the molten pool includes: identifying the molten pool boundary from the image collected by the molten pool monitoring camera and calculating the molten pool area.

[0047] (51) Extract the real-time temperature and morphological features of the molten pool based on the image and temperature data of the molten pool area; in this step, the extraction of the real-time temperature features of the molten pool includes: performing Kalman filtering on the raw temperature data collected by the thermal imaging camera to obtain an estimated temperature; calculating the first derivative of the estimated temperature with time as a heating rate feature; the extraction of the morphological features of the molten pool includes: identifying the molten pool boundary from the image collected by the molten pool monitoring camera and calculating the molten pool area S. More specifically, in this embodiment, the highest temperature at the center of the molten pool is obtained, and the rate of temperature change with time (heating / cooling rate) is calculated to determine the phase transition trend. The "aspect ratio" and "area" of the molten pool are extracted by a visual algorithm to determine whether the molten pool has collapsed or failed to fuse.

[0048] More specifically, the thermal imaging data is denoised (e.g., using Kalman filtering) to remove temperature jump noise caused by smoke or splashes. The center temperature is extracted from the thermal image, the first derivative (heating rate) is calculated, and the molten pool area S is extracted from the visible light image.

[0049] In one embodiment of the invention, the center temperature is estimated. The original measured temperature was obtained through a Kalman filter model. The corrected formula includes: Where K is the Kalman gain, The measured temperature at time t To predict temperature.

[0050] (52) Based on the extracted temperature and morphological characteristics, determine the physical phase transition stage of the material in the current molten pool; in this step, the system needs to determine the physical stage of the material in the current irradiated area. For highly reflective materials, this application divides the phase transition of the physical state of the molten pool into three stages: Highly reflective heating zone (solid state), the temperature is below the melting point, the absorption rate of infrared light is extremely low, and it mainly relies on blue / green light for heating. Phase transition jump zone (solid-liquid mixture), the temperature oscillates near the melting point, the absorption rate changes abruptly, and it is easy to generate splashes, requiring precise balance of multi-band energy. Deep melting stable zone (liquid state), completely melted, the absorption rate of infrared light is significantly improved, and red light should be mainly used to obtain deep melting depth.

[0051] In this step, the control module compares the real-time state of the molten pool with the phase transition stage of the molten pool's physical state to determine the current physical phase transition stage of the molten pool.

[0052] (53) Call the preset material property database to determine the theoretical absorption rate of the material for different wavelengths of laser light at the current physical phase transition stage and current temperature; in this step, a dynamic absorption rate estimation model needs to be constructed: in, The theoretical absorption rate of red light at temperature T is obtained from a table. The values ​​are the theoretical absorption rates of blue and green light at temperature T, respectively, obtained from a table. This represents the percentage of current laser power in each wavelength band relative to the total power. This is an estimated absorption rate.

[0053] (54) Based on the preset principle of constant target effective absorption power, and combined with the theoretical absorption rate, the output power required for each band of laser is calculated in reverse. In this step, the reverse calculation of the output power required for each band of laser follows the following energy balance model: in, These are the output power commands for red, blue, and green light, respectively. These are the corresponding wavebands at temperature The absorption rate of the material.

[0054] (55) Based on the calculated output power value, dynamically adjust the power ratio of the red, blue and green lasers in the multi-band laser generating unit.

[0055] In this step, the adjustment of the output power ratio introduces a temperature-based dynamic weighting factor. This is used to smoothly switch the dominance of short-wavelength lasers and long-wavelength lasers, and the calculation formula is as follows: in, This is the critical temperature for phase transition. The smoothing coefficient is used; the output power of the blue or green light is based on... Adjustments were made.

[0056] The dynamic adjustment of power ratio follows the following strategy: when the physical phase transition stage of the material is the solid-state high-reflectivity stage, the control module increases the weighting factor of the short-wavelength laser to make the output power mainly blue or green light, with red light as a supplement or turned off. When the physical phase transition stage of the material is the liquid deep-dissolved stage, the control module decreases the weighting factor of the short-wavelength laser to reduce the output power of blue or green light and increase the output power of red light in order to maintain the depth of the molten pool and reduce energy consumption.

[0057] Sixth, Adjustment Steps: The control module adjusts the output parameters of the multi-band laser generating unit based on the feedback data. In this step, the control module adjusts the output parameters of the multi-band laser generating module based on the feedback data, including: (1) Data fusion: Simultaneously receive infrared temperature data and visible light image data collected by the monitoring unit, and extract the real-time temperature and morphological features of the molten pool; (2) State identification: Based on the extracted temperature and morphological characteristics, determine the physical phase transition stage of the material in the current molten pool; in this step, the determination logic of the physical phase transition stage is as follows: When the estimated temperature is lower than the solidus temperature of the material, it is determined to be the solid-state high-reaction stage; when the estimated temperature is between the solidus temperature and the liquidus temperature, it is determined to be the solid-liquid phase transition stage; when the estimated temperature is higher than the liquidus temperature and the molten pool area S is within the stable threshold, it is determined to be the liquid deep melting stage.

[0058] (3) Absorption rate estimation: Call the preset material property database to determine the theoretical absorption rate of the material for different wavelengths of laser at the current physical phase transition stage and the current temperature; (4) Power back calculation: Based on the preset principle of constant effective absorption power of the target, combined with the theoretical absorption rate, the output power value required for each band of laser is calculated in reverse. (5) Command execution: Based on the calculated output power value, dynamically adjust the power ratio of the red, blue, and green lasers in the multi-band laser generating unit. The dynamic adjustment of the power ratio follows the following strategy: When it is determined that the solid-state high-reflection stage, the control module increases the weighting factor of the short-wavelength laser to make the output power mainly blue or green light, with red light as a supplement or turned off; when it is determined that the liquid deep melting stage, the control module decreases the weighting factor of the short-wavelength laser to reduce the output power of blue or green light and increase the output power of red light to maintain the depth of the molten pool and reduce energy consumption.

[0059] Furthermore, in the control method of the present invention, when switching between different materials for printing, the control module controls the corresponding wire feeding mechanism to retract after the printing of the first material is completed, and starts the wire feeding mechanism for the second material, according to the slicing path planning file (Gcode); at the same time, the control module automatically updates the target effective absorption power and theoretical absorption rate database according to the physical properties of the second material, so as to realize the adaptive switching of the photothermal process parameters of different materials.

[0060] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-band composite laser coaxial wire feeding dissimilar material additive manufacturing system, characterized in that, include: A multi-band laser generating module for generating laser beams of at least two or more different wavelength bands; A multi-channel wire feeding module for accommodating and conveying at least two or more different metal wires; A multi-band composite laser coaxial processing head is connected to the multi-band laser generating module and the multi-channel wire feeding module. It is used to coaxially couple laser beams of different wavelength bands in space to form a composite laser, and to perform optical-wire coaxial coupling between the composite laser and the conveyed metal wire. The monitoring module is used to collect real-time image data of the molten pool and temperature field data during the additive manufacturing process; as well as The control module is used to plan printing parameters based on the metal material model of the component to be printed, and to dynamically adjust the power ratio of different band laser beams in the multi-band laser generation module based on the monitoring data fed back by the monitoring module.

2. The multi-band composite laser coaxial wire feeding dissimilar material additive manufacturing system according to claim 1, characterized in that, The multi-band laser generating module includes a red laser, a blue laser, and a green laser. The multi-band composite laser coaxial processing head is provided with fiber optic interfaces arranged in a ring array, so that the red, blue, and green light output by the red, blue, and green lasers are uniformly and symmetrically distributed in a ring array in space and focused on the same point.

3. The multi-band composite laser coaxial wire feeding dissimilar material additive manufacturing system according to claim 2, characterized in that, The multi-channel filament feeding module adopts a dual-filament feeding three-channel structure, which includes a mixing filament tube and at least two independently controlled filament feeding mechanisms. The control module is used to control the alternating operation, filament feeding and retraction of the filament feeding mechanisms to achieve in-situ switching printing of dissimilar materials within a single print head.

4. The multi-band composite laser coaxial wire feeding dissimilar material additive manufacturing system according to claim 3, characterized in that, The wire feeding mechanism is a gear-driven wire feeding mechanism.

5. The multi-band composite laser coaxial wire feeding dissimilar material additive manufacturing system according to claim 3, characterized in that, It also includes a local protective gas module, which includes six protective gas outlets integrated into the multi-band composite laser coaxial processing head, and the six protective gas outlets are arranged in an array with the hybrid wire tube as the center.

6. The multi-band composite laser coaxial wire feeding dissimilar material additive manufacturing system according to claim 3, characterized in that, It also includes a water-cooling module, comprising multiple individually circulating cooling pipes, which are arranged in a ring array uniformly around the fiber optic interface.

7. A method for additive manufacturing of dissimilar materials using multi-band composite laser coaxial wire feeding, characterized in that, Includes the following steps: Step 1: Plan the printing parameters based on the metal material model of the component to be printed; Step 2: According to the printing parameters, the multi-band laser generating module is controlled to generate at least two single laser beams of different wavelength bands, and the multiple single laser beams are transmitted to the multi-band composite laser coaxial processing head and coaxially coupled in a ring array in space to form a multi-band composite laser. Step 3: Control the multi-channel wire feeding module to select one target wire from at least two types of metal wires and feed it to the central channel of the multi-band composite laser coaxial processing head, so that the target wire is coaxially coupled with the multi-band composite laser. Step four: Use the energy of the multi-band composite laser to melt the target filament, forming a molten pool and a metal deposition layer on the substrate; Step 5: Real-time acquisition of image and temperature data of the molten pool area; the control module adjusts the output parameters of the multi-band laser generating unit based on the feedback data.

8. The method for additive manufacturing of dissimilar materials using multi-band composite laser coaxial wire feeding according to claim 7, characterized in that, Step three also includes: According to the slicing path file of the metal material model, when the printing path of the first material ends, the control module controls the wire feeding mechanism corresponding to the first material to reverse and exit the first material. Then, the other wire feeding mechanism rotates forward to transport the second material to the mixing wire tube. At the same time, the control module automatically updates the target effective absorption power and material property database according to the physical properties of the second material.

9. The method for additive manufacturing of dissimilar materials using multi-band composite laser coaxial wire feeding according to claim 7, characterized in that, Step five also includes the following steps: (51) Extract the real-time temperature and morphological features of the molten pool based on the image and temperature data of the molten pool area; (52) Determine the physical phase transition stage of the material in the current molten pool based on the extracted temperature and morphological characteristics; (53) Call the preset material property database to determine the theoretical absorption rate of the material for different wavelengths of laser at the current physical phase transition stage and the current temperature; (54) Based on the preset principle of constant effective absorption power of the target, and combined with the theoretical absorption rate, the output power value required for each band of laser is calculated in reverse. (55) Based on the calculated output power value, dynamically adjust the power ratio of the red, blue and green lasers in the multi-band laser generating unit.

10. The method for additive manufacturing of dissimilar materials using multi-band composite laser coaxial wire feeding according to claim 8, characterized in that, In step (55), the dynamic adjustment of the power ratio follows the following strategy: When the material is in the physical phase transition stage of solid-state high reflectivity, the control module increases the weighting factor of short-wavelength laser to make the output power mainly blue or green light, with red light as a supplement or turned off. When the material is in the physical phase transition stage of liquid deep dissolution, the control module decreases the weighting factor of short-wavelength laser to reduce the output power of blue or green light and increase the output power of red light in order to maintain the depth of the molten pool and reduce energy consumption.

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