A laser-electron beam hybrid additive manufacturing method and system

Abstract

The present invention discloses a laser-electron beam hybrid additive manufacturing method and system, which relates to the field of laser directed energy deposition. An electron beam is used as a heat source to melt metal powder to form a molten pool on the surface of a substrate. Three indicators, namely the temperature, shape and depth of the molten pool, and surface defects, are obtained in real time. When all three meet the preset conditions, the laser is switched to be the main heat source and the electron beam is used as the auxiliary heat source to continue melting the metal powder until deposition is formed. During the collaborative work of the laser and the electron beam, an energy distribution map is constructed based on multiple detection data to obtain the temperature and shape distribution of the molten pool. Based on the temperature and shape changes of the molten pool, the laser parameters and the electron beam power parameters are adjusted in real time. The preset conditions are as follows: 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. The present invention can improve the deposition accuracy, reduce the influence of thermal stress and reduce defects, and achieve efficient energy utilization.

Description

Technical Field

[0001] The present invention relates to the field of laser directed energy deposition, and particularly to a laser-electron beam hybrid 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. However, the single laser heat source has some limitations. The energy distribution of the laser heat source presents a Gaussian distribution, resulting in local overheating of the molten pool and uneven temperature distribution in different regions, which easily causes defects such as cracks and deformations. To solve the problems of the single laser heat source, some ways of combining laser with other heat sources are disclosed in the prior art, for example:

[0003] Chinese Patent (Publication No. CN109676138A, Publication Date: April 26, 2019) discloses a laser-excited ultrasonic energy field-assisted plasma arc powder feeding additive manufacturing method. It adopts the method of coaxial powder feeding of metal powder and plasma arc, uses the plasma arc heat source as the main heat source for melting metal powder and depositing it into shape, and uses the high-frequency pulsed laser energy to impact the plasma arc molten pool to excite the ultrasonic energy field of the molten pool, so that the molten pool solidification process forms a dense and fine-grained deposited layer solidification tissue structure; this scheme combines laser and plasma arc heat sources, and it is not applicable to complex structure workpieces required in the aerospace field. Chinese Patent (Publication No. CN110064756A, Publication Date: July 30, 2019) discloses a selective laser melting forming method, which uses a first heat source to scan the powder layer; then uses a second heat source to scan the solid powder layer; wherein, the energy density of the first heat source is less than that of the second heat source; this scheme does not perform specific operations of coordinating the two heat sources.

[0004] In summary, although the above schemes involve two heat source methods, they do not consider the reasonable utilization of energy, and cannot achieve dynamic adjustment of parameters, and cannot effectively ensure work efficiency. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a laser-electron beam hybrid additive manufacturing method and system, which can improve deposition accuracy, reduce the influence of thermal stress, reduce defects, and achieve efficient energy utilization.

[0006] To achieve the above purpose, the present invention is realized through the following technical solutions:

[0007] In the first aspect, an embodiment of the present invention provides a laser-electron beam hybrid additive manufacturing method, including:

[0008] Using an electron beam as a heat source to melt metal powder and form a molten pool on the surface of a substrate; obtaining three indicators of the molten pool temperature, morphology and depth, and surface defects in real time. When all three meet the preset conditions, switch to using a laser as the main heat source and an electron beam as the auxiliary heat source, and continue to melt the metal powder until deposition is formed;

[0009] During the collaborative work of the laser and the electron beam, construct an energy distribution map 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, adjust the laser parameters and electron beam power parameters in real time;

[0010] 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.

[0011] As a further implementation method, when the electron beam is used as the auxiliary heat source, its power is lower than the electron beam power in the molten pool formation stage.

[0012] As a further implementation method, use a photodetector to obtain the laser output power in real time, use a current transformer to obtain the power output of the electron beam in real time, and use a camera to obtain the molten pool state in real time.

[0013] As a further implementation method, the stable temperature range is 1200~1400°C, the set standard range of the surface fluctuation of the molten pool is 0.2~0.5mm, and the set threshold of the defect occurrence rate is 5%.

[0014] As a further implementation method, the detection data includes the power, current, and beam morphology of the laser and the electron beam;

[0015] Establish the relationship between the power of the laser and the electron beam and the molten pool state according to the detection data, and construct a heat source input feedback model.

[0016] As a further implementation method, when the energy distribution map shows that the heat input of the laser is insufficient in the set area, automatically increase the laser power or adjust the laser focal length; when the heat input of the electron beam is too strong, automatically reduce the electron beam power or adjust the beam morphology.

[0017] As a further implementation method, the energy distribution map 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;

[0018] Combine the energy distribution map and the heat source input feedback model to obtain a collaborative optimization feedback control model.

[0019] As a further implementation method, 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.

[0020] In a second aspect, an embodiment of the present invention further provides a laser-electron beam hybrid additive manufacturing system, including:

[0021] A thermionic electron gun for emitting an electron beam;

[0022] A laser for emitting a laser;

[0023] An electron beam detection module for detecting electron beam performance parameters;

[0024] A laser detection module for detecting laser performance parameters;

[0025] A control system for automatically adjusting the electron beam and laser forms according to the electron beam performance parameters and laser performance parameters.

[0026] 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 electron beam flow state;

[0027] The laser detection module includes a photodetector and a laser focusing sensor. The photodetector is used to detect the laser output power, and the laser focusing sensor is used to detect the laser position and focus state.

[0028] The beneficial effects of the present invention are as follows:

[0029] (1) In the molten pool formation stage of the present invention, the electron beam is used as the single heat source, which can provide a wide range of heat input; in the fine deposition stage, the laser is used as the main heat source and the electron beam is used as the auxiliary heat source. The electron beam can uniformly heat a large area, and the laser can precisely control the surface morphology. The collaborative work of the two makes the control of the entire molten pool more precise, thereby improving the quality of the deposited layer; choosing a better heat source in different stages and giving full play to its comprehensive role, so as to achieve the purpose of reducing the influence of thermal stress and reducing defects.

[0030] (2) The present invention sets the switching conditions from a single heat source to a composite heat source, taking the molten pool temperature, shape and depth, and surface defects as indicators. When all three meet the set conditions, it is switched to a composite heat source to achieve the best effect. Moreover, it can dynamically adjust various parameters to ensure the optimal cooperation of the molten pool temperature and fluidity during the deposition process, thereby improving the deposition quality and efficiency and ensuring the performance and accuracy of the final part. Description of the Drawings

[0031] The specification drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0032] Figure 1It is a flowchart of the laser-electron beam hybrid additive manufacturing method according to one or more embodiments of the present invention;

[0033] Figure 2 It is a control process diagram of the laser-electron beam hybrid additive manufacturing according to one or more embodiments of the present invention;

[0034] Figure 3 It is a schematic structural diagram of the laser-electron beam hybrid additive manufacturing system according to one or more embodiments of the present invention.

[0035] Among them, 1. Powder feeding gas source, 2. Pressure valve, 3. Powder feeder, 4. Laser, 5. Substrate, 6. Protection gas source, 7. Thermal emission electron gun, 8. Electron beam, 9. Formed part, 10. Laser. Detailed implementation manners

[0036] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0037] Example 1:

[0038] This example provides a laser-electron beam hybrid additive manufacturing method, including:

[0039] Using the electron beam as a heat source to melt the metal powder and form a molten pool on the surface of the substrate; obtaining three indicators of the molten pool temperature, morphology and depth, and surface defects in real time. When all three meet the preset conditions, switch to using the laser as the main heat source and the electron beam as the auxiliary heat source, and continue to melt the metal powder until deposition is formed;

[0040] During the collaborative work of the laser and the electron beam, construct an energy distribution map 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, adjust the laser parameters and electron beam power parameters in real time;

[0041] 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.

[0042] In the initial stage (molten pool formation stage) of this example, the electron beam is used as the sole heat source, which can provide a wide range of heat input, effectively avoid local overheating problems, and at the same time help the molten pool to be heated more evenly; in the fine deposition stage, the laser is used as the main heat source and the electron beam is used as the auxiliary heat source. Under the fine processing dominated by the laser, continue to provide an appropriate amount of heat to avoid excessive local temperature difference.

[0043] Combined with Figure 1As shown in the figure, the laser-electron beam hybrid additive manufacturing method of this embodiment specifically includes the following steps:

[0044] S1: Prepare the powder and spray the powder onto the surface of the substrate.

[0045] Taking titanium alloy powder as an example, in this embodiment, Ti-6AI-4V titanium alloy powder is selected. The particle size of the powder is controlled between 50 and 150 µm. Specifically, a particle size of 100 µm is selected as the reference value. Through screening by a sieve, particles larger than 150 µm and smaller than 50 µm are removed to ensure that the particles are uniform and free of impurities.

[0046] S2: In the molten pool formation stage, use the electron beam as the only heat source. The electron beam provides sufficient heat to melt the powder and guide it to start flowing.

[0047] Among them, the electron beam power is set in the range of 4 to 10 kW 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 to 12 kW; for low thermal conductivity materials (such as titanium alloys and nickel-based alloys), the initial power is usually in the range of 4 to 8 kW.

[0048] In this embodiment, by selecting an electron beam laser power of 5KW and a scanning speed of 0.5 mm / s, the titanium alloy powder can be quickly heated and melted to 1600 °C, ensuring that the molten pool is uniformly formed throughout the working area and avoiding local overheating.

[0049] The powder delivery system precisely sprays the powder into the heating area of the electron beam through air flow. The powder spraying amount is controlled at 1 g / s to ensure uniform powder deposition and no excessive amount; at the same time, the ultrasonic vibration system starts to work, setting an ultrasonic frequency of 25 kHz and an amplitude of 20 µm. By applying high-frequency micro-vibrations in the molten pool, it helps the metal liquid to flow and reduces the generation of bubbles.

[0050] During the scanning process, the electron beam interacts with the powder, transferring the electron energy to the powder. The titanium alloy powder begins to melt, gradually fuses with the surface of the substrate, forms liquid metal, and then forms a preliminary molten pool. During the formation of the molten pool, 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 temperature of the molten pool exceeds the predetermined range of 1200 to 1400 °C, the system automatically adjusts the electron beam power to avoid quality problems caused by overheating.

[0051] As the electron beam heats and the powder gradually melts, the titanium alloy powder will be gradually guided into a stable molten pool. The shape of the molten pool should gradually become uniform and stable. Usually, in the initial stage, the depth of the molten pool is relatively shallow, approximately controlled within the range of 0.2 to 0.5 mm.

[0052] S3: Fine deposition stage, where the laser and the electron beam work together, with the laser as the main heat source and the electron beam as the auxiliary heat source.

[0053] The laser becomes the main heat source, and the power of the electron beam gradually decreases. It starts to assist in controlling the uniformity and stability of the molten pool. At this time, the laser provides a more refined heat input, while the electron beam still maintains a low power and continues to provide a uniform heat input to avoid undercooling of the molten pool. The laser focus and the scanning area of the electron beam maintain a certain overlap, but they cannot completely overlap. For example, when the electron beam scans the molten pool, its scanning area may cover an area of about 4 - 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 perform precise local heating within the scanning area of the electron beam to achieve fine control.

[0054] After the molten pool stabilizes, in order to reduce excessive melting, reduce evaporation loss, and improve the deposition quality, the power usually needs to be reduced by 30% - 50%. In this embodiment, according to the electron beam process parameters in the molten pool formation stage, the laser power is selected as 1500 W, the focal length is 7 mm, the spot size is 2 mm, and at the same time, the power of the electron beam as the auxiliary heat source is reduced to 3 Kw. The ultrasonic sound field frequency continues to be set at 25 kHz, and the amplitude is adjusted to 15 µm.

[0055] Since a single heat source of the electron beam is used in the molten pool formation stage and a composite heat source of the laser and the electron beam is used in the fine deposition stage, when switching from a single heat source to a composite heat source, the switching conditions must be met. In this embodiment, the temperature, shape and depth, and defects of the molten pool are used as three indicators in the switching conditions. When all three indicators meet the preset conditions, the switching conditions are constituted.

[0056] Furthermore, for the molten pool temperature index, since the electron beam power is set at 5 kW in the initial stage, which is mainly used to provide a large - range heat input to gradually increase and stabilize the temperature of the molten pool. At this time, the temperature of the molten pool is usually relatively high and the temperature fluctuation is large, but as the molten pool forms, the temperature gradually tends to be stable.

[0057] The average temperature of the molten pool needs to reach the set stable temperature range (1200 - 1400 °C) and remain within this range. If the temperature fluctuation is too large (exceeding the set range of ±10 °C), the switch to the laser main heat source should be delayed. In this embodiment, the temperature data at different positions on the surface of the molten pool are collected by an infrared sensor. Since the molten pool temperature varies in space and time, spatial weighting and time filtering need to be considered when calculating the average temperature.

[0058] Furthermore, since the temperature at the center of the molten pool is usually higher than that in the edge region, the temperature data are weighted - averaged:

[0059] (1)

[0060] In Equation (1), T i is the temperature at the i-th measurement point; ω i is the weight of this measurement point, usually assigned according to the distance of the measurement point from the center of the molten pool (higher weight in the central area and lower weight in the edge area).

[0061] The temperature of the molten pool fluctuates within a short period of time. Therefore, a sliding window filter is used to reduce transient errors:

[0062] (2)

[0063] In Equation (2), M is the sliding window size (such as 5 - 10 groups of data), and t is the transient time; this method can smooth the temperature curve and avoid the influence of instantaneous errors of single measurements on the decision-making.

[0064] Set a stable temperature range [T min , T max . When the following conditions are met, the temperature of the molten pool is considered stable:

[0065] ;

[0066] After 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.

[0067] Regarding the shape and depth of the molten pool, in the initial stage, the depth of the molten pool is usually relatively shallow, between 0.2 - 0.5 mm. There may be slight fluctuations and irregular shapes on the surface, but these fluctuations will be improved in the subsequent stage. When the depth of the molten pool tends to be stable and the surface fluctuations are reduced to the set standard range (depth stable at 0.3 mm and surface fluctuation amplitude lower than 0.05 mm), it indicates that the molten pool has reached a state where further fine control can be carried out.

[0068] Regarding the defects of the molten pool, in the initial stage, although the molten pool starts 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, pores, etc. appear. When the defect incidence rate is lower than the set threshold of 5%, a switch can be made. In this embodiment, a high-speed camera is used to detect the surface defects of the molten pool, such as abnormal surface roughness, cracks, spatter, etc. The defect incidence rate on the surface is expressed as:

[0069] (3)

[0070] In Equation (3), N defect is the number of detected surface defects (such as the abnormal molten pool morphology identified per unit time); N total is the number of frames of the molten pool analyzed during this time period.

[0071] Therefore, when the temperature is maintained within the target range with small fluctuations (within ±10°C), the depth and surface fluctuations of the molten pool are stable, the depth is within a predetermined range (0.2 - 0.4 mm), and the defect rate (such as cracks, pores, etc.) is lower than the set tolerance value of 5%, it indicates that the molten pool has stabilized, which is the time to switch to the laser as the main heat source.

[0072] Meanwhile, in the fine deposition stage, multiple detection data are collected by multiple sensors and transmitted to the control system. An energy distribution map is constructed, and the signals are processed based on a multi-dimensional feedback control method of the molten pool morphology and temperature field. Based on the temperature and morphology changes of the molten pool, the laser power, focal length, and scanning speed are adjusted, and at the same time, the electron beam power is adjusted to avoid local overheating or uneven heat input.

[0073] Furthermore, the detection data are obtained by corresponding sensors, including photodetectors, current transformers, Hall sensors, infrared sensors, high-speed cameras, and laser focus sensors. The photodetector is used to detect the laser output power in real time. The change in laser power will affect the local temperature of the molten pool. Whether there is power fluctuation or excessive concentration is judged according to the real-time power data fed back by the photodetector; the current transformer is used to detect the power output of the electron beam. The change in current can reflect the intensity of the beam current, 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 (deviating 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.

[0074] The focal position and beam shape of the laser directly affect the formation of the molten pool. If the laser beam is not accurately focused or the light spot is shifted, the heating effect of the laser will be affected; therefore, the focal state of the laser is monitored in real time through the laser focus sensor 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.

[0075] To ensure the uniformity of heat input when the two heat sources work together, the collected data (power, current, beam morphology, etc.) need to be comprehensively analyzed through the energy distribution map and the heat source input feedback model.

[0076] Furthermore, the heat source input of the laser and the electron beam can be modeled through the power density distribution. By monitoring the power output, current, beam morphology, etc. of the laser and the electron beam in real time through sensors, the distribution of energy in the molten pool can be calculated. The energy distribution map can be represented by the power density model, that is, the non-uniform model of energy distribution:

[0077] (4)

[0078] 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 ;

[0079] P laser (t) is the laser power input, P e−beam (t) the power input of the electron beam, varying with time;

[0080] 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).

[0081] 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.

[0082] 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:

[0083] Temperature feedback model:

[0084] 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:

[0085] (5)

[0086] 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.

[0087] Heat source input adjustment model:

[0088] 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:

[0089] (6)

[0090] In Equation (6), T max (t) is the maximum temperature on 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.

[0091] Equation (6) combines the feedback of the molten pool temperature and the beam profile, and can, based on real-time monitoring of the molten pool state, maintain the uniformity of heat input by dynamically adjusting the powers of the laser and the electron beam.

[0092] The heat source input feedback model establishes the relationship between the powers of the laser and the electron beam and the molten pool state. When data such as temperature, beam state, and power change, the heat source input feedback model can provide a real-time judgment on whether the current heat input state meets the process requirements. If the heat input of a certain heat source (such as the laser or the electron beam) is insufficient, or a certain area is overheated, the output parameters of the heat source are adjusted through the control system.

[0093] For example: If the energy distribution map shows that the heat input of the laser is insufficient in some areas, the system will automatically increase the laser power or adjust the laser focal length to precisely heat these areas. If the heat input of the electron beam is too strong, causing overheating in some areas, the control system can appropriately reduce the power of the electron beam or adjust the beam profile to make the heat input distribution more uniform.

[0094] The heat input Q can be determined by factors such as the heat source power, scanning speed, spot / beam size, etc., and its calculation method is as follows:

[0095] (7)

[0096] In Equation (7), P is the heat source power (W), including the laser power P L and the electron beam power P E , A is the spot / beam coverage area (mm 2 ), v is the scanning speed (mm / s).

[0097] In this embodiment, by combining the heat source input feedback model with the energy distribution map, a collaborative optimization feedback control model is constructed to ensure the coordinated heat input of the laser and the electron beam to guarantee a stable and uniform temperature distribution of the molten pool.

[0098] The collaborative optimization feedback control model is expressed as:

[0099] (8)

[0100] In Equation (8), is the total heat input to a certain area of the molten pool, x 1~ x 2 and y 1~ y 2 ranges are the boundaries of the molten pool in the sensor detection or control area, which can be dynamically adjusted according to sensor data to ensure precise control of the heat input to the entire molten pool area. E target is the target energy density of 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 width of the molten pool, reflecting the influence of the change in the molten pool shape on the heat source adjustment; δ1 and δ2 are adjustment exponents related to the change in the molten pool shape.

[0101] Based on the above formula, in this embodiment, through the energy distribution map and the morphological characteristics of the molten pool, precise adjustment of the laser and electron beam power is achieved, and the heat input of the two can be adjusted based on real-time feedback to ensure the stability and uniformity of the molten pool.

[0102] 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:

[0103] (9)

[0104] In formula (9), is the ratio of the depth to the width of the molten pool, is the ratio of the depth to the height of the molten pool, used to describe the change in the molten pool shape; α3, α4, β3, β4 are adjustment coefficients to control the sensitivity of the system response.

[0105] S4: Later stage (forming completion and post-processing):

[0106] Deposition completion: The laser and electron beam continue to cooperate until the titanium alloy layer deposition is completed, forming the target complex structure. During each layer deposition process, a scanning speed of 0.2 mm / s is adopted to control the uniformity and defect-free of each layer deposition.

[0107] Cooling and forming: After the deposition is completed, through the automatic cooling control system, the molten pool is gradually cooled to room temperature to avoid thermal stress and deformation, and annealing heat treatment is carried out to improve the mechanical properties of the titanium alloy.

[0108] The deposited finished product is subjected to non-destructive testing by X-ray detection and ultrasonic detection to ensure no internal defects, and the dimensional accuracy of the deposited titanium alloy component is inspected to ensure that it meets the design requirements.

[0109] 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.

[0110] 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.

[0111] Embodiment 2:

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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, 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, is installed near the focusing coil of the electron beam 8, close to the path of the electron beam 8, and avoids direct bombardment of the sensor by the electron beam 8 to cause damage.

[0116] It also includes an infrared sensor and a high-speed camera. The infrared sensor is used to monitor the temperature distribution of the entire area, is installed above the molten pool, and the field of view covers the entire molten pool area; it needs to maintain 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, the field of view covers the dynamic process of the molten pool, and is designed with air cooling protection against high temperatures, equipped with a microsecond-level shutter to capture the transient changes of the molten pool.

[0117] In this embodiment, different sensors respectively cover key areas such as the molten pool, and avoid mutual occlusion or interference during use; moreover, key data (molten pool temperature) can be cross-validated through multiple sensors (infrared + high-speed camera thermal imaging).

[0118] The timing control of multiple sensor data fusion pairs is mainly to generate a synchronous pulse signal by the FPGA main controller, trigger all sensors to collect data simultaneously, ensure time synchronization, and accurately reflect the transient state of the molten pool. This method is a prior art and will not be elaborated here. The above sensors are all connected to the control system, and the control system automatically adjusts the shapes of the electron beam 8 and the laser 10 according to the performance parameters of the electron beam 8 and the performance parameters of the laser 10.

[0119] In this embodiment, through the cooperation of the thermal emission electron gun 7 and the laser 4, only the electron gun works in the initial stage, and in the molten pool formation stage, the thermal emission electron gun 7 and the laser 4 work together to finally form the formed part 9.

[0120] In this embodiment, through reasonable power ratio and relative position control, the laser 10 and the electron beam 8 can complement each other, achieving efficient energy utilization and making the additive manufacturing process more stable and efficient. This embodiment is particularly suitable for the processing of complex components in the aerospace field.

[0121] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A laser-electron beam hybrid additive manufacturing method, characterized in that, Including: Using an electron beam as a heat source to melt metal powder and form a molten pool on the surface of the substrate; Obtaining three indicators of the molten pool temperature, shape and depth, and surface defects in real time. When all three meet the preset conditions, switch to using a laser as the main heat source and an electron beam as the auxiliary heat source, and continue to melt the metal powder until deposition is formed; During the collaborative work of the laser and the electron beam, construct an energy distribution map based on multiple detection data to obtain the temperature and shape distribution of the molten pool; based on the temperature and shape changes of the molten pool, adjust the laser power, laser focal length, electron beam power and beam shape in real time; Among them, the preset conditions are: the molten pool temperature 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.

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

3. A laser-electron beam hybrid additive manufacturing method according to claim 1 or 2, characterized in that Use a photodetector to obtain the laser output power in real time, use a current transformer to obtain the power output of the electron beam in real time, and use a camera to obtain the molten pool state in real time.

4. A laser-electron beam hybrid additive manufacturing method according to claim 1, characterized in that The stable temperature range is 1200~1400°C, the set standard range of the surface fluctuation of the molten pool is that the depth is stable at 0.3mm, the surface fluctuation amplitude is lower than 0.05mm, and the set threshold of the defect incidence rate is 5%.

5. A laser-electron beam hybrid additive manufacturing method according to claim 1, wherein The detection data includes the laser power and the power of the electron beam, the current of the electron beam, the beam shape of the electron beam, and the focus state of the laser; Establish the relationship between the power of the laser and the electron beam and the molten pool state according to the detection data, and construct a heat source input feedback model.

6. A laser-electron beam hybrid additive manufacturing method according to claim 1 or 5, characterized in that, When the energy distribution map shows that the heat input of the laser is insufficient in the set area, automatically increase the laser power or adjust the laser focal length; when the heat input of the electron beam is too strong, automatically reduce the electron beam power or adjust the beam shape.

7. A laser-electron beam hybrid additive manufacturing method according to claim 5, characterized in that The energy distribution map 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; Combine the energy distribution map and the heat source input feedback model to obtain a collaborative optimization feedback control model.

8. A laser-electron beam hybrid additive manufacturing method according to claim 1, wherein 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 system for a laser-electron beam hybrid additive manufacturing method according to any one of claims 1-8, characterized in that, Including: A thermal emission electron gun for emitting an electron beam; A laser for emitting a laser; An electron beam detection module for detecting electron beam performance parameters; A laser detection module for detecting laser performance parameters; A control system for adjusting the laser power, laser focal length, electron beam power and beam shape in real time based on the temperature and shape changes of the molten pool.

10. The system of a laser-electron beam hybrid additive manufacturing method according to claim 9, wherein 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 electron beam flow state; The laser detection module includes a photodetector and a laser focusing sensor. The photodetector 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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