Laser electron beam composite additive manufacturing method and system

Abstract

The invention discloses a laser electron beam composite additive manufacturing method and system, and relates to the field of laser directional energy deposition, an electron beam is used as a heat source to melt metal powder, and a molten pool is formed on the surface of a substrate; three indexes including the temperature, the form and depth and the surface defect of the molten pool are obtained in real time, and when the three indexes meet preset conditions at the same time, laser serves as a main heat source, electron beams serve as an auxiliary heat source, and the metal powder continues to be molten till deposition is formed; in the cooperative working process of the laser and the electron beam, an energy distribution diagram is constructed based on multiple pieces of detection data, and temperature and form distribution of a molten pool are obtained; laser parameters and electron beam power parameters are adjusted in real time based on the temperature and form changes of the molten pool; the preset conditions are that the average temperature of the molten pool reaches a set stable temperature interval, the surface fluctuation of the molten pool is reduced to a set standard range, and the defect occurrence rate is lower than a set threshold value. The deposition precision can be improved, the thermal stress influence can be reduced, defects can be reduced, and efficient energy utilization is achieved.

Description

Technical Field

[0001] The present invention relates to the field of laser directional energy deposition, and in particular to a laser electron beam composite additive manufacturing method and system. Background Art

[0002] Generally, laser directed energy deposition (L-DED) additive manufacturing mainly relies on a single laser heat source, but a single laser heat source has some limitations. The energy distribution of the laser heat source presents a Gaussian distribution, which leads to local overheating of the molten pool and uneven temperature distribution in different areas, which easily causes defects such as cracks and deformation. In order to solve the problem of a single laser heat source, some methods of laser superimposing other heat sources are disclosed in the prior art, such as: Chinese patent (publication number CN109676138A, publication date 2019.04.26) discloses a laser-stimulated ultrasonic energy field-assisted plasma arc powder-carrying additive manufacturing method, which adopts the method of coaxial powder feeding of metal powder and plasma arc, uses plasma arc heat source as the main heat source to melt metal powder and deposit it, and uses high-frequency pulse laser energy to impact the plasma arc molten pool, stimulates the generation of molten pool ultrasonic energy field, so that the molten pool smelting process forms a dense and fine-grained deposition layer molten structure; this scheme uses laser and plasma arc heat sources, which is not suitable for complex structure workpieces required in the aerospace field. Chinese patent (publication number CN110064756A, publication date 2019.07.30) discloses a method of selective laser melting forming, which uses a first heat source to scan the powder layer; then uses a second heat source to scan the powder solid layer; wherein the energy density of the first heat source is less than the energy density of the second heat source; this scheme does not perform specific operations of the two heat sources working together.

[0003] In summary, although the above scheme involves two heat source methods, it does not take into account the rational use of energy, and cannot achieve dynamic adjustment of parameters and cannot effectively guarantee work efficiency. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a laser electron beam composite additive manufacturing method and system, which can improve deposition accuracy, reduce the impact of thermal stress and defects, and achieve efficient energy utilization.

[0005] In order to achieve the above object, the present invention is implemented through the following technical solutions: In a first aspect, an embodiment of the present invention provides a laser electron beam composite additive manufacturing method, comprising: Use electron beam as heat source to melt metal powder and form a molten pool on the substrate surface; obtain three indicators of molten pool temperature, morphology and depth, and surface defects in real time. When the three indicators meet the preset conditions at the same time, switch to laser as the main heat source and electron beam as the auxiliary heat source to continue melting the metal powder until deposition is formed; During the collaborative work of laser and electron beam, an energy distribution diagram is constructed based on multiple detection data to obtain the temperature and morphology distribution of the molten pool; based on the temperature and morphology changes of the molten pool, the laser parameters and electron beam power parameters are adjusted in real time; Among them, the preset conditions are: the average temperature of the molten pool reaches the set stable temperature range, the surface fluctuation of the molten pool is reduced to the set standard range, and the defect occurrence rate is lower than the set threshold.

[0006] As a further implementation, when the electron beam is used as an auxiliary heat source, its power is lower than the electron beam power in the molten pool formation stage.

[0007] As a further implementation method, a photoelectric detector is used to obtain the laser output power in real time, a current transformer is used to obtain the power output of the electron beam in real time, and a camera is used to obtain the molten pool state in real time.

[0008] As a further implementation method, the stable temperature range is 1200~1400℃, the set standard range of the molten pool surface fluctuation is 0.2~0.5mm, and the set threshold value of the defect occurrence rate is 5%.

[0009] As a further implementation, the detection data includes the power, current, and beam shape of the laser and electron beam; The relationship between the power and the molten pool state corresponding to the laser and electron beam is established based on the detection data, and a heat source input feedback model is constructed.

[0010] As a further implementation method, the energy distribution diagram shows that when the laser heat input in the set area is insufficient, the laser power is automatically increased or the laser focal length is adjusted; when the electron beam heat input is too strong, the electron beam power is automatically reduced or the beam shape is adjusted.

[0011] As a further implementation, the energy distribution diagram is represented by a power density model; the heat source input feedback model includes a temperature feedback model and a heat source input adjustment model; The energy distribution diagram is combined with the heat source input feedback model to obtain a collaborative optimization feedback control model.

[0012] As a further implementation, when the laser and the electron beam work together, there is a set overlapping area between the laser focus and the electron beam scanning area.

[0013] In a second aspect, an embodiment of the present invention further provides a laser electron beam composite additive manufacturing system, comprising: A thermal emission electron gun for emitting an electron beam; Laser, used for emitting laser light; An electron beam detection module, used to detect electron beam performance parameters; Laser detection module, used to detect laser performance parameters; The control system is used to automatically adjust the electron beam and laser morphology according to the electron beam performance parameters and the laser performance parameters.

[0014] As a further implementation, the electron beam detection module includes a current transformer and a Hall sensor, the current transformer is used to detect the power output of the electron beam, and the Hall sensor is used to detect the flow state of the electron beam; The laser detection module includes a photoelectric detector and a laser focusing sensor. The photoelectric detector is used to detect the laser output power, and the laser focusing sensor is used to detect the laser position and focus state.

[0015] The beneficial effects of the present invention are as follows: (1) In the molten pool formation stage, the present invention uses electron beam as a single heat source, which can provide a wide range of heat input; in the fine deposition stage, laser is used as the main heat source and electron beam is used as the auxiliary heat source. The electron beam can heat a large range evenly, and the laser can accurately control the surface morphology. The coordinated work of the two makes the entire molten pool control more precise, thereby improving the quality of the deposited layer; a better heat source is selected at different stages to give full play to its comprehensive role, thereby achieving the purpose of reducing the impact of thermal stress and reducing defects.

[0016] (2) The present invention sets the switching conditions from a single heat source to a composite heat source, taking the molten pool temperature, morphology and depth, and surface defects as indicators. When all three meet the set conditions, the composite heat source is switched to achieve the best effect. In addition, various parameters can be dynamically adjusted to ensure the optimal combination of molten pool temperature and fluidity during the deposition process, thereby improving the deposition quality and efficiency and ensuring the performance and precision of the final product. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0018] Figure 1 is a flow chart of a laser electron beam composite additive manufacturing method according to one or more embodiments of the present invention; Figure 2 is a control process diagram of laser electron beam composite additive manufacturing according to one or more embodiments of the present invention; Figure 3 It is a schematic diagram of the structure of a laser electron beam composite additive manufacturing system according to one or more embodiments of the present invention.

[0019] Among them, 1. powder feeding gas source, 2. air pressure valve, 3. powder feeder, 4. laser, 5. substrate, 6. protective gas source, 7. thermal emission electron gun, 8. electron beam, 9. formed part, 10. laser. DETAILED DESCRIPTION It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0020] Embodiment 1: This embodiment provides a laser electron beam composite additive manufacturing method, including: Use electron beam as heat source to melt metal powder and form a molten pool on the substrate surface; obtain three indicators of molten pool temperature, morphology and depth, and surface defects in real time. When the three indicators meet the preset conditions at the same time, switch to laser as the main heat source and electron beam as the auxiliary heat source to continue melting the metal powder until deposition is formed; During the collaborative work of laser and electron beam, an energy distribution diagram is constructed based on multiple detection data to obtain the temperature and morphology distribution of the molten pool; based on the temperature and morphology changes of the molten pool, the laser parameters and electron beam power parameters are adjusted in real time; Among them, the preset conditions are: the average temperature of the molten pool reaches the set stable temperature range, the surface fluctuation of the molten pool is reduced to the set standard range, and the defect incidence rate is lower than the set threshold.

[0021] In the initial stage (molten pool formation stage), this embodiment uses electron beam as the only heat source, which can provide a large range of heat input, effectively avoid local overheating problems, and help the molten pool to be heated more evenly; in the fine deposition stage, laser is used as the main heat source and electron beam is used as the auxiliary heat source. Under laser-dominated fine processing, it continues to provide an appropriate amount of heat to avoid excessive local temperature differences.

[0022] Combination Figure 1 As shown, the laser electron beam composite additive manufacturing method of this embodiment specifically includes the following steps: S1: Prepare powder and spray the powder onto the surface of the substrate.

[0023] Taking titanium alloy powder as an example, this embodiment selects Ti-6AI-4V titanium alloy powder, and the powder particle size is controlled between 50 and 150 µm. Specifically, a particle size of 100 µm is selected as a reference value. The particles larger than 150 µm and smaller than 50 µm are removed through sieve screening to ensure that the particles are uniform and free of impurities.

[0024] S2: The melt pool formation stage uses electron beam as the only heat source, which provides enough heat to melt the powder and guide it to start flowing.

[0025] The electron beam power is set in the range of 4~10kW to ensure sufficient energy to melt the powder and form a stable molten pool. For high thermal conductivity materials (such as aluminum alloys and copper alloys), a higher initial power is required, usually in the range of 6~12kW; for low thermal conductivity materials (such as titanium alloys and nickel-based alloys), the initial power is usually in the range of 4~8kW.

[0026] In this embodiment, an electron beam laser power of 5 kW and a scanning speed of 0.5 mm / s are selected, which can rapidly heat and melt the titanium alloy powder to 1600° C., ensuring that the molten pool is uniformly formed in the entire working area and avoiding local overheating.

[0027] The powder delivery system precisely sprays the powder into the heating area of ​​the electron beam through airflow. The powder spraying amount is controlled at 1g / s to ensure uniform and non-excessive powder deposition. At the same time, the ultrasonic vibration system starts working, setting an ultrasonic frequency of 25kHz and an amplitude of 20µm. By applying high-frequency micro-vibrations in the molten pool, it helps the metal liquid flow and reduces the generation of bubbles.

[0028] The electron beam interacts with the powder during the scanning process, transferring electron energy to the powder. The titanium alloy powder begins to melt and gradually merges with the substrate surface to form liquid metal, and then forms a preliminary molten pool. During the molten pool formation process, the temperature of the molten pool area is monitored in real time by an infrared sensor and fed back to the control system. If the molten pool temperature exceeds the predetermined range of 1200~1400℃, the system automatically adjusts the electron beam power to avoid quality problems caused by overheating.

[0029] As the electron beam heats and the powder gradually melts, the titanium alloy powder will be gradually guided into a stable molten pool. The morphology of the molten pool should gradually become uniform and stable. Usually in the initial stage, the depth of the molten pool is shallow, approximately controlled within the range of 0.2~0.5mm.

[0030] S3: In the fine deposition stage, laser and electron beam work together, with laser as the main heat source and electron beam as the auxiliary heat source.

[0031] The laser becomes the main heat source, and the electron beam power gradually decreases, starting to assist in controlling the uniformity and stability of the molten pool. At this point, the laser provides a more refined heat input, while the electron beam still maintains low power and continues to provide uniform heat input to avoid overcooling of the molten pool. The laser focus and the electron beam scanning area maintain a certain overlap, but not completely overlap; for example, when the electron beam scans the molten pool, its scanning area may cover an area of ​​about 4 to 5 mm, while the laser focus may only be 2 mm; the center of the laser focus should be located on the surface of the molten pool, and precise local heating should be performed within the scanning area of ​​the electron beam to achieve fine control.

[0032] After the molten pool is stabilized, in order to reduce over-melting, reduce evaporation loss and improve deposition quality, the power usually needs to be reduced by 30% to 50%. In this embodiment, according to the electron beam process parameters in the molten pool formation stage, the laser power is selected to be 1500W, the focal length is 7 mm, and the spot size is 2mm. At the same time, the power of the electron beam as an auxiliary heat source is reduced to 3Kw, the ultrasonic sound field frequency is still set to 25kHz, and the amplitude is adjusted to 15µm.

[0033] Since the molten pool formation stage uses a single heat source of electron beam, and the fine deposition stage uses a composite heat source of laser and electron beam, when switching from a single heat source to a composite heat source, the switching condition must be met. In this embodiment, the temperature, morphology and depth, and defects of the molten pool are used as three indicators in the switching condition. When all three indicators meet the preset conditions, the switching condition is constituted.

[0034] Furthermore, for the molten pool temperature index, since the electron beam power is set to 5kW in the initial stage, it is mainly used to provide a large range of heat input, so that the molten pool temperature gradually increases and reaches stability. At this time, the temperature of the molten pool is usually high and the temperature fluctuates greatly, but as the molten pool is formed, the temperature gradually stabilizes.

[0035] The average temperature of the molten pool needs to reach the set stable temperature range (1200~1400℃) and remain within this range. If the temperature fluctuates too much (exceeding the set ±10℃ range), the switch to the laser main heat source should be delayed. In this embodiment, the temperature data of different positions on the surface of the molten pool are collected by infrared sensors. Since the temperature of the molten pool varies in space and time, spatial weighting and time filtering need to be considered when calculating the average temperature.

[0036] Furthermore, since the temperature in the center of the molten pool is usually higher than that in the edge area, the temperature data is weighted averaged: (1) In formula (1), T i is the temperature of the ith measurement point; ω i is the weight of the measurement point, which is usually assigned according to the distance of the measurement point from the center of the molten pool (the center area has a higher weight and the edge area has a lower weight).

[0037] The molten pool temperature fluctuates in a short period of time, so a sliding window filter is used to reduce transient errors: (2) In formula (2), M is the sliding window size (such as 5 to 10 sets of data), and t is the transient time. This method can smooth the temperature curve and avoid the instantaneous error of a single measurement from affecting the decision.

[0038] Set the stable temperature range [T min,T max ], the molten pool temperature is considered stable when the following conditions are met: ; When the stable conditions are met, the heat source mode can be switched or the power parameters of the laser and electron beam can be optimized.

[0039] As for the molten pool morphology and depth, in the initial stage, the depth of the molten pool is usually shallow, between 0.2 and 0.5 mm, and there may be slight fluctuations and irregular shapes on the surface, but these fluctuations will be improved in the subsequent stages. When the depth of the molten pool tends to be stable and the surface fluctuation is reduced to the set standard range (the depth is stable at 0.3 mm and the surface fluctuation amplitude is less than 0.05 mm), it indicates that the molten pool has reached a state that can be further finely controlled.

[0040] As for the molten pool defects, in the initial stage, although the molten pool begins to form under electron beam heating, there may be defects such as pores and cracks. The surface defects of the molten pool are monitored by a high-speed camera, especially whether cracks and pores appear. When the defect incidence rate is lower than the set threshold of 5%, switching can be performed. In this embodiment, a high-speed camera is used to detect surface defects of the molten pool, such as abnormal surface roughness, cracks, spatter, etc. The surface defect incidence rate is expressed as: (3) In formula (3), N defect is the number of surface defects detected (e.g., abnormal weld pool morphology identified per unit time); N total is the number of melt pool frames analyzed during this time period.

[0041] Therefore, when the temperature is kept within the target range and the fluctuation is small (within ±10°C), the molten pool depth and surface fluctuation are stable, the depth is within the predetermined range (0.2-0.4mm), and the defect rate (such as cracks, pores, etc.) is lower than the set tolerance value of 5%, it means that the molten pool has stabilized, and it is time to switch to the laser as the main heat source.

[0042] At the same time, in the fine deposition stage, multiple detection data are collected through multiple sensors and transmitted to the control system to construct an energy distribution diagram. The signal is processed based on a multi-dimensional feedback control method of the molten pool morphology and temperature field. The laser power, focal length and scanning speed are adjusted based on the temperature and morphology changes of the molten pool, and the electron beam power is adjusted at the same time to avoid local overheating or uneven heat input.

[0043] Furthermore, the detection data is acquired by corresponding sensors, including photodetectors, current transformers, Hall sensors, infrared sensors, high-speed cameras and laser focusing sensors. The photodetector is used to detect the laser output power in real time. The change of laser power will affect the local temperature of the molten pool. The real-time power data fed back by the photodetector can be used to determine whether there is power fluctuation or excessive concentration; the current transformer is used to detect the power output of the electron beam. The change of current can reflect the intensity of the beam, which in turn affects the heat input; the Hall sensor is used to detect the beam morphology of charged particles such as electron beams. The beam morphology refers to the width, shape and focal position of the electron beam; if the beam morphology is unstable (deviates from the preset path), the heat input of the electron beam will be uneven; therefore, the stability of the beam can be monitored in real time through the Hall sensor.

[0044] The focal position and beam shape of the laser directly affect the formation of the molten pool. If the laser beam is not precisely focused or the spot is offset, the heating effect of the laser will be affected. Therefore, the laser focus sensor is used to monitor the focus state of the laser in real time to ensure that it is consistent with the predetermined position. The infrared sensor is used to monitor the temperature distribution of the entire area, and the high-speed camera captures the morphological changes of the molten pool through high-frequency images to monitor the state of the molten pool.

[0045] In order to ensure the uniformity of heat input when the two heat sources work together, the collected data (power, current, beam shape, etc.) need to be comprehensively analyzed through energy distribution diagrams and heat source input feedback models.

[0046] Furthermore, the heat source input of the laser and electron beam can be modeled by the power density distribution. By using sensors to monitor the power output, current, beam shape, etc. of the laser and electron beam in real time, the energy distribution in the molten pool can be calculated. The energy distribution diagram can be represented by the power density model, that is, the non-uniform model of energy distribution: (4) In formula (4), E(x,y,t) is the local energy density at the position (x,y) of the molten pool, and the unit is W / m 2 ; P laser (t) is the laser power input, P e−beam (t) the power input of the electron beam, varying with time; f laser (x, y) is the spatial distribution function of the laser on the molten pool surface, f e−beam (x, y) is the spatial distribution function of the electron beam on the surface of the molten pool, describing the distribution of energy on the surface of the molten pool; usually, f laser (x,y) and f e−beam (x,y) is related to the shape of the heat source (such as laser spot and electron beam shape).

[0047] In practical applications, the above function can be dynamically adjusted based on the changes in the molten pool morphology. The energy distribution of the laser is generally Gaussian, while the distribution of the electron beam depends on the geometry and focusing state of the beam.

[0048] The heat source input feedback model not only needs to consider the distribution of power density, but also needs to adjust the working parameters of the heat source according to the state of the molten pool (such as temperature and shape); by real-time monitoring of feedback signals such as temperature and shape, the system can optimize the heat input distribution. Therefore, it includes: Temperature feedback model: According to the thermal dynamic characteristics of the molten pool, the temperature change is nonlinearly related to the heat source input; the local temperature of the molten pool can be expressed as: (5) In formula (5), T(x, y, t) is the local temperature of a certain position in the molten pool, α laser is the laser heat transfer coefficient, α e−beam is the electron beam thermal conductivity coefficient, which depends on the material and thermal conductivity characteristics of the molten pool; the integral term represents the cumulative effect of the heat source input on the local temperature, which is continuously updated over time.

[0049] Heat source input adjustment model: According to the local temperature and shape (such as depth and width) of the molten pool and the real-time energy distribution, the power of the laser and electron beam can be dynamically adjusted through the heat source input feedback: (6) In formula (6), T max (t) is the maximum temperature of the molten pool surface; T target (t) is the target temperature; I beam (t) is the actual beam current of the electron beam; I beam,target is the target beam current of the electron beam; β1 and β2 are adjustment coefficients that control the sensitivity of the feedback response.

[0050] Equation (6) combines the feedback of the molten pool temperature and beam morphology. It can maintain the uniformity of heat input by dynamically adjusting the power of the laser and electron beam based on real-time monitoring of the molten pool state.

[0051] The heat source input feedback model establishes the relationship between the power of the laser and electron beam and the state of the molten pool. When the temperature, beam state, power and other data change, the heat source input feedback model can provide real-time judgment whether the current heat input state meets the process requirements. If a heat source (such as a laser or electron beam) has insufficient heat input, or a certain area is overheated, the output parameters of the heat source are adjusted through the control system.

[0052] For example, if the energy distribution diagram shows that the heat input of the laser is insufficient in certain areas, the system will automatically increase the laser power or adjust the focus of the laser to precisely heat these areas. If the heat input of the electron beam is too strong, causing certain areas to overheat, the control system can appropriately reduce the power of the electron beam or adjust the beam shape to make the heat input distribution more uniform.

[0053] The heat input Q can be determined by factors such as heat source power, scanning speed, spot / beam size, etc., and is calculated as follows: (7) In formula (7), P is the heat source power (W), including the laser power P L and electron beam power P E , A is the spot / beam coverage area (mm 2 ), v is the scanning speed (mm / s).

[0054] This embodiment combines the heat source input feedback model with the energy distribution diagram to construct a collaborative optimization feedback control model to ensure that the heat input of the laser and electron beams are coordinated with each other to ensure a stable and uniform temperature distribution in the molten pool.

[0055] The collaborative optimization feedback control model is expressed as: (8) In formula (8), is the total heat input to a certain area of ​​the molten pool, x 1~ x 2 and y 1~ y The range of 2 is the boundary of the molten pool in the sensor detection or control area, which can be dynamically adjusted according to the sensor data to ensure accurate control of the heat input of the entire molten pool area. target is the target energy density in this area, γ1 and γ2 are adjustment coefficients used to adjust the power output of the laser and electron beam; d(t) is the depth of the molten pool, ω(t) is the molten pool width, reflecting the influence of the change of the molten pool morphology on the heat source adjustment; δ1 and δ2 are adjustment indexes related to the change of the molten pool morphology.

[0056] Based on the above formula, this embodiment realizes precise adjustment of laser and electron beam power through energy distribution diagram and morphological characteristics of the molten pool, and can adjust the heat input of both based on real-time feedback to ensure the stability and uniformity of the molten pool.

[0057] In order to further optimize the deposition process of the molten pool, a multi-dimensional feedback control mode can be constructed by combining multiple morphological information such as the depth, width and height of the molten pool: (9) In formula (9), is the ratio of the molten pool depth to width, It is the ratio of the molten pool depth to the height, which is used to describe the change in the molten pool morphology; α3, α4, β3, and β4 are adjustment coefficients, which control the sensitivity of the system response.

[0058] S4: Later stage (forming completion and post-processing): Deposition is completed: The laser and electron beam continue to cooperate until the titanium alloy layer is deposited and the target complex structure is formed. During the deposition of each layer, a scanning speed of 0.2mm / s is used to control the deposition of each layer to be uniform and defect-free.

[0059] Cooling and forming: After deposition is completed, the molten pool is gradually cooled to room temperature through an automatic cooling control system to avoid thermal stress and deformation, and annealing heat treatment is performed to improve the mechanical properties of the titanium alloy.

[0060] The deposited finished products are non-destructively tested through X-ray and ultrasonic testing to ensure that there are no internal defects, and the deposited titanium alloy components are inspected for dimensional accuracy to ensure that they meet the design requirements.

[0061] This embodiment uses a composite heat source of laser and electron beam. The high precision of the laser can control the surface melting, while the electron beam helps to heat a larger area, making the heat distribution of the entire molten pool more uniform; the combination of the two can play different roles at different stages to ensure the deposition quality. During the deposition process, the ultrasonic sound field is applied to generate vibrations in the deposition area, which helps to enhance the fluidity of the molten pool and promote the discharge of bubbles, thereby reducing the generation of pores.

[0062] This embodiment can effectively solve the problems of uneven heat input, unstable molten pool, cracks, pores, etc. in L-DED by combining laser and electron beam composite heat sources and ultrasonic sound field assistance; and can dynamically adjust various parameters in real time to ensure the optimal coordination of molten pool temperature and fluidity during the deposition process, thereby improving deposition quality and efficiency and ensuring the performance and precision of the final formed part.

[0063] Embodiment 2: This embodiment provides a laser electron beam composite additive manufacturing system, combined with Figure 3 As shown, it includes a thermal emission electron gun 7, a laser 4, an electron beam detection module and a laser detection module, the laser 4 is respectively connected to a protective gas source 6 and a powder conveying system, wherein the powder conveying system includes a powder feeding gas source 1 and a powder feeder 3 connected in sequence, and a pressure valve 2 is installed in the pipeline between the powder feeding gas source 1 and the powder feeder 3. In this embodiment, the protective gas source 6 and the powder feeding gas source 1 are respectively filled with argon gas.

[0064] The laser 4 is arranged above the substrate 5, and the thermal emission electron gun 7 is arranged on one side of the laser 4. The thermal emission electron gun 7 is used to emit an electron beam 8; the laser 4 is used to emit a laser 10; in the initial stage, only the thermal emission electron gun 7 works, and in the molten pool formation stage, the thermal emission electron gun 7 and the laser 4 work together, with the laser 4 as the main one and the thermal emission electron gun 7 as the auxiliary one.

[0065] The laser detection module includes a photodetector and a laser focus sensor. The photodetector is used to detect the output power of the laser 10. It is installed on the laser 4 and is set close to the output end of the laser 10. Its specific installation position should avoid blocking the light beam. The photodetector forms a 45° angle with the path of the laser 10 to capture scattered light or reflected light signals. The laser focus sensor is used to detect the position and focus state of the laser 10. It is set on the side of the head of the laser 4 and is aligned with the exit point of the laser 10.

[0066] The electron beam detection module includes a current transformer and a Hall sensor. The current transformer is used to detect the power output of the electron beam 8. It is installed on the thermal emission electron gun 7 and is electromagnetically shielded to prevent the high-frequency noise of the electron beam 8 from affecting the signal. The Hall sensor is used to detect the flow state of the electron beam 8. It is installed near the focusing coil of the electron beam 8, close to the path of the electron beam 8, and avoids damage caused by direct bombardment of the electron beam 8 on the sensor.

[0067] It also includes infrared sensors and high-speed cameras. The infrared sensor is used to monitor the temperature distribution of the entire area. It is installed above the molten pool, and its field of view covers the entire molten pool area. It needs to keep a certain distance from the molten pool to avoid high-temperature damage. In addition, a sapphire glass high-temperature protection window can be used to prevent metal vapor from contaminating the lens. The high-speed camera captures the morphological changes of the molten pool through high-frequency images and is used to monitor the state of the molten pool. It is installed on the side of the molten pool, and its field of view covers the dynamic process of the molten pool. It is designed with air cooling protection and high temperature resistance, and is equipped with a microsecond shutter to capture transient changes in the molten pool.

[0068] In this embodiment, different sensors cover key areas such as the molten pool, respectively, and avoid mutual occlusion or interference between them during use; and key data (molten pool temperature) can be cross-verified by multiple sensors (infrared + high-speed camera thermal imaging).

[0069] The timing control of multiple sensor data fusion pairs is mainly generated by the FPGA main controller to generate a synchronous pulse signal, which triggers all sensor acquisitions at the same time to ensure time synchronization to accurately reflect the transient molten pool state. This method is a prior art and will not be repeated here. The above sensors are all connected to the control system, and the control system automatically adjusts the electron beam 8 and laser 10 according to the performance parameters of the electron beam 8 and the performance parameters of the laser 10.

[0070] In this embodiment, the thermal emission electron gun 7 and the laser 4 cooperate with each other. In the initial stage, only the electron gun works. In the molten pool forming stage, the thermal emission electron gun 7 and the laser 4 work together to finally form a formed part 9.

[0071] In this embodiment, through reasonable power ratio and relative position control, the laser 10 and the electron beam 8 can complement each other to achieve efficient energy utilization, making the additive manufacturing process more stable and efficient. This embodiment is particularly suitable for the processing of complex components in aerospace.

[0072] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A laser electron beam composite additive manufacturing method, characterized in that: include: The electron beam is used as a heat source to melt the metal powder and form a molten pool on the substrate surface; The three indicators of molten pool temperature, morphology and depth, and surface defects are obtained in real time. When the three indicators meet the preset conditions at the same time, the laser is switched as the main heat source and the electron beam is used as the auxiliary heat source to continue melting the metal powder until a deposit is formed. During the collaborative work of laser and electron beam, an energy distribution diagram is constructed based on multiple detection data to obtain the temperature and morphology distribution of the molten pool; based on the temperature and morphology changes of the molten pool, the laser parameters and electron beam power parameters are adjusted in real time; Among them, the preset conditions are: the molten pool temperature reaches the set stable temperature range, the molten pool surface fluctuation is reduced to the set standard range, and the defect occurrence rate is lower than the set threshold.

2. The laser electron beam composite additive manufacturing method according to claim 1, characterized in that: When the electron beam is used as an auxiliary heat source, its power is lower than the electron beam power in the molten pool forming stage.

3. A laser electron beam composite additive manufacturing method according to claim 1 or 2, characterized in that: A photoelectric detector is used to obtain the laser output power in real time, a current transformer is used to obtain the power output of the electron beam in real time, and a camera is used to obtain the molten pool state in real time.

4. The laser electron beam composite additive manufacturing method according to claim 1, characterized in that: The stable temperature range is 1200-1400°C, the set standard range of the molten pool surface fluctuation is 0.2-0.5mm, and the set threshold value of the defect occurrence rate is 5%.

5. The laser electron beam composite additive manufacturing method according to claim 1, characterized in that: The detection data includes the power, current and beam shape of the laser and electron beam; The relationship between the power and the molten pool state corresponding to the laser and electron beam is established based on the detection data, and a heat source input feedback model is constructed.

6. A laser electron beam composite additive manufacturing method according to claim 1 or 5, characterized in that: The energy distribution diagram shows that when the heat input of the laser in the set area is insufficient, the laser power is automatically increased or the laser focal length is adjusted; when the heat input of the electron beam is too strong, the electron beam power is automatically reduced or the beam shape is adjusted.

7. The laser electron beam composite additive manufacturing method according to claim 5, characterized in that: The energy distribution diagram is represented by a power density model; the heat source input feedback model includes a temperature feedback model and a heat source input adjustment model; The energy distribution diagram is combined with the heat source input feedback model to obtain a collaborative optimization feedback control model.

8. The laser electron beam composite additive manufacturing method according to claim 1, characterized in that: When the laser and the electron beam work together, there is a set overlapping area between the laser focus and the electron beam scanning area.

9. A laser electron beam composite additive manufacturing system, characterized in that: include: A thermal emission electron gun for emitting an electron beam; Laser, used for emitting laser light; An electron beam detection module, used to detect electron beam performance parameters; Laser detection module, used to detect laser performance parameters; The control system is used to automatically adjust the electron beam and laser morphology according to the electron beam performance parameters and the laser performance parameters.

10. The laser electron beam composite additive manufacturing system according to claim 9, characterized in that: The electron beam detection module includes a current transformer and a Hall sensor, wherein the current transformer is used to detect the power output of the electron beam, and the Hall sensor is used to detect the flow state of the electron beam; The laser detection module includes a photoelectric detector and a laser focusing sensor. The photoelectric detector is used to detect the laser output power, and the laser focusing sensor is used to detect the laser position and focus state.

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