An adaptive control gas protection device for laser additive manufacturing

Abstract

The present invention relates to an adaptively controlled gas protection device for laser additive manufacturing, which is intended to provide efficient inert gas protection to reduce oxidation of the molten pool and improve the quality of the additive layer. The device is provided with a protective cover on the laser cladding head, and the inside of the protective cover is connected to the air nozzle via a spherical hinge to spray inert gas to form a protective atmosphere. In order to ensure the stability and directionality of the airflow, the protective gas disc is connected to the protective cover via a slide rail, and the distance between the protective gas disc and the substrate is adjusted in real time by a distance sensor and a servo motor drive system to maintain the optimal spacing for gas protection. At the same time, four groups of zoned air injection holes and corresponding gas pipes are provided under the disc. These gas pipes are connected to the gas solenoid valve system, which can automatically adjust the gas injection area according to the movement direction of the cladding head, ensuring dynamic protection of the additive layer and reducing oxidation. The specially designed hinge slider mechanism is linked to the air nozzle to prevent the protective airflow from disturbing the powder flow, so that stable powder delivery is maintained during the defocus adjustment process.

Description

Technical Field

[0001] The present invention relates to the field of laser additive manufacturing, and in particular to an adaptively controlled gas protection device for laser additive manufacturing. Background Art

[0002] Additive Manufacturing (AM), as an advanced manufacturing technology, has been widely adopted in recent years in a variety of high-value-added fields, including aerospace, automotive, molds, and medical. Laser AM, a key branch of this technology, uses lasers as a heat source to melt metal powder or wire on a substrate surface, then stacks them layer by layer to form the desired structure or part. This process, due to its advantages such as the ability to manufacture complex structures, high material utilization, and shortened manufacturing cycles, has gradually become an important means of manufacturing and repairing key components. However, during the laser AM process, effectively controlling the oxidation of AM products remains a challenge that affects AM quality.

[0003] The basic principle of laser additive manufacturing is to heat metal powder with a high-energy laser beam, melting it and forming an additive layer on the substrate surface. However, at high temperatures, molten metal easily undergoes oxidation reactions with ambient oxygen, leading to oxide inclusions in the additive layer, which can affect the material's mechanical properties and surface quality. Especially when manufacturing demanding structural parts or repairing critical components, oxidation can lead to material embrittlement, reduced wear resistance, and decreased corrosion resistance, thus affecting the overall component lifespan.

[0004] To address this issue, it's often necessary to create an inert gas environment around the molten pool to isolate the oxygen in the air. Common inert gases such as argon or nitrogen can effectively reduce the presence of oxygen and minimize oxidation. However, traditional gas shielding methods typically employ fixed air nozzles or simple gas hoods. These methods are unable to adjust the gas shield in real time based on dynamic operating conditions such as the laser cladding head's motion path, defocus adjustment, and the state of the molten pool, resulting in the continued risk of oxidation in localized areas.

[0005] During laser additive manufacturing (LAM), metal powder is precisely delivered to the molten pool surface via a powder delivery system. A stable and uniform powder flow is crucial for forming dense and uniform additive layers. However, conventional gas shielding systems, lacking the flexibility to adjust the nozzle angle, can disrupt the powder flow, affecting powder deposition accuracy. Excessive gas disturbance can lead to uneven powder dispersion and even flyaways, severely impacting the final build quality.

[0006] During the laser additive manufacturing process, the laser cladding head must frequently adjust its defocus according to process requirements to accommodate varying machining needs. This adjustment prevents the shielding gas jet direction and flow intensity from being synchronized, which can easily disrupt the powder delivery path, preventing accurate powder deposition in the molten pool and affecting the material's forming quality.

[0007] Traditional laser additive manufacturing gas protection devices have exposed several technical difficulties in practical applications:

[0008] (1) Uneven inert gas protection: Existing devices mostly use simple gas hoods or fixed air nozzles. The inert gas protection range is limited, and it is difficult to achieve dynamic adjustment according to the movement state of the laser cladding head, and it is impossible to provide a full range and stable protective atmosphere;

[0009] (2) The protective gas flow is unstable during the defocus adjustment process: When the laser cladding head adjusts the defocus, the fixed angle of the protective gas nozzle of the protective cover easily disturbs the powder flow and cannot be adjusted in real time with the change of defocus, causing the powder flow trajectory to deviate, thereby affecting the quality of the additive manufacturing part.

[0010] (3) High gas consumption and low protection efficiency: Due to the lack of precise control, the traditional inert gas protection method usually requires a large amount of gas to form a sufficient protective atmosphere, resulting in serious gas waste and increased production costs. Summary of the Invention

[0011] In order to solve the technical problems existing in the prior art, the present invention discloses an adaptively adjustable gas protection device for laser additive manufacturing;

[0012] The technical solution adopted in the present invention is as follows:

[0013] An adaptively adjustable gas protection device for laser additive manufacturing comprises an outer cylinder and a cladding head, wherein a laser light path channel is provided in the center of the outer cylinder; a powder feeding pipe is fixedly installed on a platform in the middle of the outer cylinder, and the powder feeding pipe is used to transport easily oxidized metal powder; an anti-slip gun body is connected to the bottom of the outer cylinder, and the bottom of the anti-slip gun body is connected to the cladding head, and the bottom of the cladding head is connected to a protective gas disc; a driving device and a gas solenoid valve are fixed to the outer ring of the outer cylinder, and the driving device drives the protective gas disc to slide relative to the cladding head; the gas solenoid valve is connected to one end of the gas pipe, and the other end of the gas pipe is connected to the protective gas disc; a plurality of air inlet openings connected to the gas pipe are provided on the protective gas disc, and a group of inert gas pipelines are installed under each air inlet opening, and the multiple groups of inert gas pipelines are independently controlled by the gas solenoid valve.

[0014] As a further technical solution, the cladding head includes a first nozzle, a cladding head shell and a gas shield. The outer platform of the first nozzle is fixedly connected to the cladding head shell, and the gap between the two forms an inert gas channel; the lower end of the cladding head shell is fixedly connected to the gas shield; the conical inner wall of the gas shield is seamlessly matched with the outer wall of the first nozzle, and is combined with the cladding head shell to form a chamber, the chamber is connected to the inert gas channel, and the gas shield area on the lower side of the chamber is provided with square grooves distributed in a circumferential manner. The lower end of the groove is spherical, and a hemispherical hinge is arranged in the groove. A gas channel is provided in the middle of the hemispherical hinge, which forms a hemispherical hinge jet pipe with the second nozzle; the hemispherical hinge jet pipe is connected to the chamber and the inert gas channel.

[0015] As a further technical solution, a conical ring is provided on the inner side of the thin-walled ring at the upper end of the shielding gas disc, and a hinge is fixedly installed on the conical ring. The hinge and the first slider form a slider hinge structure, and the first slider is sleeved on the hemispherical hinge jet pipe of the cladding head.

[0016] As a further technical solution, two second sliders are symmetrically provided on the outer side of the thin ring wall at the upper end of the protective gas disc, and grooves are opened at corresponding positions on the inner side of the thin ring wall at the lower end of the gas protective cover, forming a slide rail structure between the protective gas disc and the gas protective cover.

[0017] As a further technical solution, the protective gas disc consists of a cover plate, a disc base and an inert gas pipeline. The cover plate and the disc base are fixedly connected by a snap buckle. The outer side of the upper end of the cover plate is connected to the driving device through a T-shaped connector and a connecting plate. An air inlet pipe opening is fixedly installed on the cover plate.

[0018] As a further technical solution, each group of inert gas pipelines consists of several interconnected radial pipelines and circumferential pipelines. A pipeline opening is provided above each group of inert gas pipelines, which is connected to the air inlet pipe port. At the same time, the bottom of the inert gas pipeline is connected to the inert gas nozzle on the disc base, forming four gas pipelines branched out by the gas solenoid valve, and the connected air inlet pipe port, pipeline opening, inert gas pipeline and inert gas nozzle form a protective gas disc gas protection path.

[0019] As a further technical solution, a water cooling pipe is provided above the disc base, and the water cooling pipe is used to cool down and protect the protective gas disc.

[0020] As a further technical solution, a distance measuring sensor is provided under the disc base. The distance measuring sensor can detect the vertical distance between the shielding gas disc and the additive area in real time. After data processing, the sensor transmits instructions to the driving device, which drives the shielding gas disc to move up and down.

[0021] As a further technical solution, the gas solenoid valve includes a valve body and multiple control valve cores; an air inlet is provided at the upper end of the valve body, which is connected to the gas cylinder through a pipeline, and the lower part of the air inlet is connected to multiple chambers in the gas solenoid valve, each chamber is connected to an airway corresponding to a different direction, and the opening and closing of different airways are controlled by independent control valve cores in the corresponding directions.

[0022] As a further technical solution, the control valve core consists of an electromagnet, a return spring, a connecting shaft and a valve core, and the valve core is provided with a vent hole parallel to the airway; the valve core and the electromagnet are connected by a connecting shaft, and a return spring is mounted on the connecting shaft.

[0023] The beneficial effects of the present invention are as follows:

[0024] The adaptive control gas protection device for laser additive manufacturing proposed in this invention can intelligently adjust the inert gas injection according to the real-time motion state of the laser cladding head, the change in defocus amount, and the processing path. The details are as follows:

[0025] (1) Dynamic airflow control can be achieved: the shielding gas device can adjust the spray direction and intensity of the inert gas according to the movement state and path change of the cladding head through the design of the gas solenoid valve, shielding gas disc and inert gas pipeline, so as to ensure that the inert gas covers the high-temperature molten pool and forms all-round protection; the gas spraying area can be reasonably allocated according to the movement trajectory of the cladding head to achieve optimal utilization of gas resources, reduce gas waste and reduce production costs.

[0026] (2) Adaptive adjustment of the defocus amount can be achieved: when the shielding gas disk moves up and down, the hinge fixed on the conical ring drives the slider to slide on the hemispherical hinge jet tube. The hemispherical hinge jet tube swings radially under the drive of the slider, changing the angle between the hemispherical hinge jet tube and the vertical direction, so that the hemispherical hinge jet tube can adjust the angle synchronously with the movement of the shielding gas disk; that is, as the defocus amount of the laser cladding head changes, the device should be able to synchronously adjust the angle and height of the gas injection to avoid the airflow disturbing the powder flow, thereby maintaining the stability of the powder flow.

[0027] (3) Accurate real-time feedback and control: A distance sensor is set under the disc base. The distance sensor can detect the vertical distance between the shielding gas disc and the additive area in real time. After data processing, it sends instructions to the drive device. The drive device drives the shielding gas disc to move up and down. Combined with the real-time feedback of the distance sensor, it ensures that the shielding gas disc and the additive area maintain the set distance range.

[0028] In summary, the dynamic gas shielding device of this invention will significantly improve the quality of laser additive manufacturing, particularly in the processing of high-value-added parts and complex structures. It can effectively reduce oxidation and enhance the mechanical properties and surface quality of the finished product. Furthermore, the device's intelligent gas control system can reduce inert gas consumption, conserve resources, and improve production economics. As additive manufacturing technology continues to expand across various industries, this invention will provide key technical support for process optimization in laser additive manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 An overall schematic diagram of the gas protection device for laser additive manufacturing;

[0030] Figure 2 A half-section diagram of a gas shielding device for laser additive manufacturing;

[0031] Figure 3 This is a half-section schematic diagram of the gas protection device of the cladding head;

[0032] Figure 4 It is a partial schematic diagram of the hemispherical hinged jet pipe;

[0033] Figure 5 This is a schematic diagram of the shielding gas disc;

[0034] Figure 6 It is a half-section view of the shielding gas disc;

[0035] Figure 7 It is a half-section schematic diagram of a gas solenoid valve;

[0036] Figure 8 Schematic diagram of the open ring.

[0037] In the figure: 1. outer cylinder; 11. powder feeding pipe; 2. gas solenoid valve; 21. connecting plate; 22. electromagnet; 23. return spring; 24. connecting shaft; 25. air channel; 26. valve core; 27. valve body; 28. air inlet; 29. ​​chamber; 3. opening ring; 31. threaded hole; 4. drive device; 41. servo motor; 42. slide rail base; 43. lead screw; 44. lead screw nut; 45. connecting plate; 46. T-type connector; 5. anti-slip gun body; 6. cladding head; 61. first nozzle; 611. air inlet pipe; 61 2. Inert gas channel; 62. Cladding head housing; 63. Gas shield; 631. Hemispherical hinged jet pipe; 6311. Hinge; 6312. First slider; 6313. Hemispherical hinge; 6314. Second nozzle; 7. Shielding gas disc; 71. Cover plate; 711. Inlet pipe opening; 712. Buckle; 713. Conical ring; 714. Second slider; 72. Disc base; 721. Distance sensor; 722. Inert gas pipeline; 723. Inert gas nozzle; 724. Pipe opening; 8. Gas pipe. DETAILED DESCRIPTION

[0038] In order to better understand the technical content of the present invention, specific embodiments are given and described below with reference to the accompanying drawings.

[0039] Various aspects of the present invention are described in this disclosure with reference to the accompanying drawings, in which a number of illustrative embodiments are shown. The embodiments of the present disclosure are not necessarily intended to include all aspects of the present invention. It should be understood that the various concepts and embodiments described above, as well as those described in more detail below, can be implemented in many ways with any coaxial powder fed laser cladding head using a gas anti-slip shield protection device, as the concepts and embodiments disclosed herein are not limited to any embodiment. In addition, some aspects of the present disclosure may be used alone or in any appropriate combination with other aspects of the present disclosure.

[0040] In the laser direct energy deposition (LDED) additive manufacturing (AM) process, when using easily oxidizable metal powders (such as titanium, aluminum, and their alloys), oxidation can easily occur when the molten pool comes into contact with air. LDED technology uses a high-energy-density laser beam as a heat source. The high temperature environment causes the molten pool to form oxides with oxygen in the air. Furthermore, the high-temperature additive layer near the molten pool reacts with oxygen, and during the subsequent deposition process, surface oxides are remelted and enter the molten pool. The presence of oxides increases inclusions in the post-solidification microstructure and reduces the mechanical properties of the material. The coaxial air-blowing shielding method currently used in LDED suffers from limited airflow protection range and low gas utilization efficiency, especially at high scanning speeds. Therefore, the protection effect is further limited by creating a relatively closed inert atmosphere zone within the molten pool to further reduce the risk of molten pool oxidation. A shielding gas disc is designed to increase the protection range, thereby providing more effective protection for the high-temperature additive area. A gas solenoid valve is also included to meet the protection requirements of complex paths and reduce inert gas consumption. Finally, combined with the ranging sensor, the gas protection device and the injection hole angle are synchronously regulated based on the change in laser defocus, ensuring the protection effect while avoiding disrupting the powder feeding.

[0041] Combine Figure 1 and Figure 2 As shown, this embodiment provides an improved LDED gas protection device, including an outer cylinder 1, a gas solenoid valve 2, an open ring 3, a driving device 4, an anti-slip gun body 5, a cladding head 6, a protective gas disc 7 and a gas pipe 8;

[0042] A laser light path channel is provided at the center of the outer cylinder 1; the driving device 4 is fixed to the outer ring of the outer cylinder 1 through the open ring 3; the driving device 4 drives the shielding gas disc 7 to move up and down; the anti-slip gun body 5 is connected to the bottom of the outer cylinder 1, the bottom of the anti-slip gun body 5 is connected to the cladding head 6, and the bottom of the cladding head 6 is connected to the shielding gas disc 7; and a gas solenoid valve 2 is installed on the outside of the outer cylinder 1, and the gas solenoid valve 2 is connected to one end of the gas pipe 8, and the other end of the gas pipe 8 is connected to the shielding gas disc 7; a powder feeding pipe 11 is fixedly installed on the platform in the middle of the outer cylinder 1, and the powder feeding pipe 11 is used to transport easily oxidizable metal powder. When the powder reaches the area overlapping with the laser beam, it is melted by the high-energy laser beam to achieve material deposition.

[0043] Furthermore, a flange is provided at the upper end of the outer cylinder 1, and a plurality of threaded interfaces are opened on the flange. The threaded interfaces are connected to the robot arm via screws, so that the laser cladding head can perform additive manufacturing experiments in a follow-up manner. In addition, the side of the flange at the upper end of the outer cylinder 1 is also connected to a vertically placed connecting plate 21 via screws. The connecting plate 21 is used to install the gas solenoid valve 2.

[0044] Furthermore, two open rings 3 are fixed on the outer surface of the outer cylinder 1, and a threaded hole 31 is opened on each side of the opening of one side of the open ring 3. The open ring 3 is tightened on the outer cylinder 1 by screwing the two threaded holes 31; a connecting plate is provided on the other side of the open ring 3, and the connecting plate is connected to the driving device 4; specifically, the driving device 4 includes a slide rail base 42, a servo motor 41, a lead screw 43, a lead screw nut 44 and a connecting plate 45; the connecting plate is fixedly connected to the slide rail base 42 by screws; the slide rail base 42 is placed vertically The servo motor 41 is arranged on the upper platform of the slide rail base 42. The servo motor 41 is connected to the lead screw 43 that vertically passes through the circular hole of the upper platform of the slide rail base 42. The lead screw 43 is driven by the servo motor 41 to drive the lead screw nut 44 to move up and down along the guide rail. The outer side of the lead screw nut 44 is fixedly connected to the connecting plate 45 by screws, and the T-shaped connecting piece 46 connects the connecting plate 45 and the shielding gas disc 7 by screws. The shielding gas disc 7 can achieve synchronous up and down movement with the lead screw nut 44 through the connecting plate 45 and the T-shaped connecting piece 46.

[0045] Furthermore, the lower end of the outer cylinder 1 is connected to the anti-slip gun body 5 through a threaded connection, and the lower platform of the anti-slip gun body 5 is provided with a threaded hole connected to the cladding head 6;

[0046] Furthermore, the cladding head 6 includes a first nozzle 61, a cladding head shell 62, and a gas shield 63; the first nozzle 61 is fixedly connected to the lower platform of the anti-slip gun body 5 by screws, and an inert gas inlet pipe 611 is fixedly installed on the outer platform of the first nozzle 61. During laser additive manufacturing, it is connected to the gas supply mechanism through a gas pipeline to deliver inert gas (argon, etc.) to the cladding head 6. The outer platform of the first nozzle 61 is also fixedly connected to the cladding head shell 62 by screws. After the cladding head shell 62 is fixedly connected to the first nozzle 61, the gap between the two forms an inert gas channel 612. The upper end of the inert gas channel 612 is connected to the inert gas inlet pipe 611, and the lower end of the cladding head shell 62 is fixedly connected to the gas shield 63 by threads. The gas shield 63 is conical. The inner wall seamlessly matches the outer wall of the first nozzle 61 and is combined with the cladding head shell 62 to form a chamber, which is connected to the inert gas channel 612. The gas shield 63 area on the lower side of the chamber is provided with square grooves distributed in a circumference. The lower end of the groove is spherical, and a hemispherical hinge 6313 is placed in the groove. A gas channel is provided in the middle of the hemispherical hinge 6313, which forms a hemispherical hinge injection pipe 631 with the second nozzle 6314. The hemispherical hinge injection pipe 631 is connected to the chamber and the inert gas channel 612. During laser additive manufacturing, the inert gas delivered from the inert gas inlet pipe 611 passes through the inert gas channel 612 and the chamber, and is sprayed into the gas shield 63 from the hemispherical hinge injection pipe 631 to form an inert gas atmosphere, thereby protecting the molten pool.

[0047] Furthermore, two second sliders 714 are symmetrically provided on the outer side of the thin ring wall at the upper end of the protective gas disc 7, and grooves are opened at corresponding positions on the inner side of the thin ring wall at the lower end of the gas protective cover 63. A slide rail structure is formed between the protective gas disc 7 and the gas protective cover 63. At the same time, the plane where the two second sliders 714 are located is parallel to the connecting plate 45. When the driving device 4 drives the protective gas disc 7 to move up and down, the second slider 714 can avoid lateral deviation of the protective gas disc 7 and ensure the stability of the movement.

[0048] Furthermore, a tapered ring 713 is provided on the inner side of the thin-walled ring at the upper end of the shielding gas disc 7. A hinge 6311 is fixedly mounted on the tapered ring 713. The hinge 6311 and a first slider 6312 form a slider-hinge structure. The first slider 6312 is sleeved onto the second nozzle 6314 of the hemispherical hinged air jet 631. As the shielding gas disc 7 moves up and down, the hinge 6311 fixed to the tapered ring 713 drives the first slider 6312 to slide on the hemispherical hinged air jet 631. Driven by the first slider 6312, the hemispherical hinged air jet 631 swings radially, changing its angle with the vertical. This allows the hemispherical hinged air jet 631 to adjust its angle synchronously with the movement of the shielding gas disc 7. That is, adaptive adjustment of the defocus amount can be achieved: as the defocus amount of the laser cladding head changes, the device should be able to synchronously adjust the angle and height of the gas injection to avoid the airflow disturbing the powder flow, thereby maintaining the stability and accuracy of the powder flow.

[0049] Furthermore, the shielding gas disc 7 comprises a cover plate 71, a disc base 72, and an inert gas pipe 722. The cover plate 71 and the disc base 72 are fixedly connected by a buckle 712. The outer side of the upper end of the cover plate 71 is connected to the drive device 4 via a T-shaped connector 46 and a connecting plate 45. Furthermore, an air inlet port 711 is fixedly mounted on the cover plate 71. The air inlet port 711 is connected to the gas solenoid valve 2 via a gas pipe 8 to control the supply of inert gas. In this embodiment, the inert gas conduits 722 are installed within the chamber of the shielding gas disc 7 and are divided into four groups, located at the front, rear, left, and right of the shielding gas disc 7. Each group of inert gas conduits consists of several interconnected radial and circumferential conduits. Each group of inert gas conduits 722 has a conduit opening 724 above it, which connects to the air inlet 711. Simultaneously, the inert gas conduits 722 communicate with the inert gas nozzles 723 on the disc base 72 at their lower sides, forming a gas protection path for the shielding gas disc 7, consisting of the four gas delivery pipes 8 branching from the gas solenoid valve 2, the air inlet 711, the conduit openings 724, the inert gas conduits 722, and the inert gas nozzles 723 connected thereto. It should be noted that the inert gas conduits 722 are not limited to the four groups of "front," "rear," "left," and "right" shown in this embodiment; five, six, or seven groups, etc., may also be provided, with the multiple groups of inert gas conduits 722 uniformly distributed along the circumference of the shielding gas disc 7.

[0050] Furthermore, the inert gas pipelines 722 in the “front”, “rear”, “left” and “right” directions are connected to the four gas passages 25 of the gas solenoid valve 2 via the four groups of gas inlet ports 711 and the gas delivery pipe 8;

[0051] Further, such as Figure 7As shown, the gas solenoid valve 2 includes a valve body 27 and four control valve cores; one control valve core controls the connection between one chamber 29 and one airway; an air inlet hole 28 is provided at the upper end of the valve body 27, which is connected to the gas cylinder through a pipeline, and the lower end of the air inlet hole is connected to the four chambers 29 in the gas solenoid valve 2. The four chambers are connected to the airways 25 corresponding to the "front", "rear", "left" and "right" directions respectively. The opening and closing of the four groups of airways are controlled by independent control valve cores corresponding to the "front", "rear", "left" and "right" directions respectively.

[0052] Furthermore, each control valve core includes a valve core 26, a return spring 23, an electromagnet 22 and a connecting shaft 24; the valve core 26 is horizontally arranged in the middle of the chamber 29 of the valve body 27; a vent hole parallel to the airway 25 is opened on the valve core 26; the valve core 26 and the electromagnet 22 are connected by a connecting shaft 24, and a return spring 23 is mounted on the connecting shaft 24, and the return spring 23 controls the valve core 26 to reset; when performing laser additive manufacturing, a scanning path is set. When the scanning path is a straight path, according to the "front", "back", "left" and "right" movement data of the scanning path, the corresponding "back", "front", "right" and "left" directional electromagnet 22 power-on instructions are deduced through computer analysis. After the electromagnet 22 corresponding to the "back", "front", "right" and "left" directional is energized, the valve core 26 moves along the connecting shaft 24, and the vent hole on the valve core 26 is collinear with the airway 25 to allow the inert gas to circulate and be transported to the protective gas through the gas pipe 8. The gas shielding disc 7 causes the inert gas nozzles 723 in the "rear", "front", "right" and "left" directions to spray gas. In addition, when the scanning path direction changes, for example, after the scanning direction changes from "front" to "right", the electromagnet 22 in the previous "rear" direction is powered off, and the valve core 26 is reset under the action of the reset spring 23, and the air duct 25 is closed again. The inert gas nozzle 723 in the "rear" direction of the protective gas disc 7 no longer sprays gas, but the inert gas nozzle 723 in the "left" direction starts to spray protection. The above process is realized under a straight scanning path, and the molten pool is in a semi-closed inert gas atmosphere formed by the gas shield 63, while the high-temperature additive area in the rear is always in the inert protective atmosphere formed by the protective gas disc 7, so as to greatly reduce the degree of oxidation in the easily oxidized area and improve the performance of the additive part. At the same time, no protective gas will be sprayed in other directions of the molten pool, which saves inert gas and improves the utilization rate of the inert gas. When the scanning path follows a complex curve, a computer analysis and deduction program simultaneously controls the power supply of multiple solenoid valves, enabling one or more groups of inert gas nozzles 723 to spray air, protecting the additively manufactured part along the complex path. This allows for dynamic airflow control, where the protective gas device automatically adjusts the direction and intensity of the inert gas flow based on the cladding head's motion, path changes, and environmental parameters, ensuring that the inert gas covers the entire high-temperature molten pool for all-around protection. Precise control of the gas distribution system allows the gas injection area to be rationally allocated based on the cladding head's motion trajectory, achieving optimal utilization of gas resources, minimizing gas waste, and lowering production costs.

[0053] Furthermore, a water cooling pipe (not shown) is provided above the disc base 72 , and the water cooling pipe cools down the shielding gas disc 7 to prevent the shielding gas disc 7 from being overheated and damaging the gas shielding path.

[0054] Furthermore, a distance measuring sensor 721 is provided below the disc base 72. The distance measuring sensor 721 can detect the vertical distance between the shielding gas disc 7 and the additive area in real time, and transmit a signal to the servo motor 41 after data processing to control the servo motor 41 to drive the shielding gas disc 7 to move up and down. Combined with the real-time feedback from the distance measuring sensor 721, it is ensured that the shielding gas disc 7 and the additive area maintain a set distance range.

[0055] The dynamic gas shielding device designed for laser cladding additive manufacturing is designed to provide efficient inert gas protection to reduce molten pool oxidation and improve the quality of the additive layer. The device features a shield mounted on the laser cladding head. A short-tube air nozzle is connected to the inside of the shield via a spherical hinge, spraying inert gas to create a protective atmosphere. To ensure the stability and directionality of the airflow, a shielding gas disc is connected to the shield via a slide rail. The distance between the disc and the substrate is adjusted in real time via a rangefinder and a servo motor control system to maintain the optimal spacing between the gas shield layers. Four sets of zoned air holes and corresponding air pipes are located beneath the disc. These air pipes are connected to an electromagnetic control system and can automatically adjust the gas injection area according to the direction of movement of the cladding head, ensuring dynamic protection of the additive layer and reducing oxidation. A specially designed hinged slider mechanism is linked to the air nozzle to prevent the shielding airflow from disturbing the powder flow, ensuring stable powder delivery during defocus adjustment.

[0056] This invention is used in laser cladding additive manufacturing processes and is particularly well-suited for inert gas protection of the molten pool and high-temperature additive layers. By dynamically adjusting the gas injection direction and optimizing airflow control, it can effectively reduce oxidation reactions, improve the stability and surface quality of the additive process, and is particularly suitable for the manufacture of large, high-value-added parts. This device solves the problems of oxidation and airflow disturbance of powders in traditional laser additive manufacturing, improving process precision and efficiency. It has broad industrial application prospects and will contribute to technological advancements in the field of additive manufacturing.

Claims

1. An adaptively controlled gas shielding device for laser additive manufacturing, comprising an outer cylinder and a cladding head, wherein a laser light path is provided in the center of the outer cylinder; a powder feeding pipe is fixedly mounted on a platform in the middle of the outer cylinder, and the powder feeding pipe is used to transport easily oxidizable metal powder, characterized in that: The bottom of the outer cylinder is connected to an anti-slip gun body, the bottom of the anti-slip gun body is connected to a cladding head, the bottom of the cladding head is connected to a shielding gas disc, a driving device and a gas solenoid valve are fixed to the outer ring of the outer cylinder, the driving device drives the shielding gas disc to slide relative to the cladding head, the gas solenoid valve is connected to one end of the gas supply pipe, the other end of the gas supply pipe is connected to the shielding gas disc, the shielding gas disc is provided with a plurality of air inlet ports connected to the gas supply pipe, a group of inert gas pipelines are installed under each air inlet port, and the multiple groups of inert gas pipelines are independently controlled by the gas solenoid valve; The cladding head includes a first nozzle, a cladding head housing, and a gas shield. The outer platform of the first nozzle is fixedly connected to the cladding head housing, and the gap between the two forms an inert gas channel. The lower end of the cladding head housing is fixedly connected to the gas shield. The conical inner wall of the gas shield seamlessly matches the outer wall of the first nozzle and is combined with the cladding head housing to form a chamber. The chamber is connected to the inert gas channel. The gas shield area on the lower side of the chamber is provided with square grooves distributed in a circumferential manner. The lower end of the groove is spherical, and a hemispherical hinge is arranged in the groove. The gas channel is provided in the middle of the hemispherical hinge, which forms a hemispherical hinge injection pipe with the second nozzle. The hemispherical hinge injection pipe is connected to the chamber and the inert gas channel. A conical ring is provided on the inner side of the thin-walled ring at the upper end of the shielding gas disc, and a hinge is fixedly mounted on the conical ring. The hinge and the first slider form a slider hinge structure, and the first slider is sleeved on the hemispherical hinge jet pipe of the cladding head; Two second sliding blocks are symmetrically arranged on the outer side of the thin ring wall at the upper end of the protective gas disc, and grooves are opened on the inner side of the thin ring wall at the lower end of the gas protective cover at corresponding positions, forming a slide rail structure between the protective gas disc and the gas protective cover.

2. The adaptive control gas protection device for laser additive manufacturing according to claim 1, characterized in that: The protective gas disc consists of a cover plate, a disc base and an inert gas pipeline. The cover plate and the disc base are fixedly connected by a buckle. The outer side of the upper end of the cover plate is connected to the driving device through a T-shaped connector and a connecting plate. The cover plate is fixedly installed with an air inlet pipe.

3. The adaptive control gas protection device for laser material addition according to claim 2, characterized in that: Each group of inert gas pipelines consists of several interconnected radial pipelines and circumferential pipelines. A pipeline opening is provided above each group of inert gas pipelines, which is connected to the air inlet pipe port. At the same time, the bottom of the inert gas pipeline is connected to the inert gas nozzle on the disc base, forming four gas pipelines branched by the gas solenoid valve, and the connected air inlet pipe port, pipeline opening, inert gas pipeline and inert gas nozzle form a gas protection path for the protective gas disc.

4. The adaptive control gas protection device for laser additive manufacturing according to claim 2, characterized in that: A water cooling pipe is provided above the disc base, and the water cooling pipe is used to cool down and protect the protective gas disc.

5. The adaptive control gas protection device for laser material addition according to claim 2, characterized in that: A distance measuring sensor is provided under the disc base. The distance measuring sensor can detect the vertical distance between the shielding gas disc and the additive area in real time. After data processing, the sensor transmits instructions to the driving device, which drives the shielding gas disc to move up and down.

6. The adaptive control gas protection device for laser additive manufacturing according to claim 1, characterized in that: The gas solenoid valve includes a valve body and multiple control valve cores; an air inlet is provided at the upper end of the valve body, which is connected to the gas cylinder through a pipeline, and the lower part of the air inlet is connected to multiple chambers in the gas solenoid valve, each chamber is connected to an airway corresponding to a different direction, and the opening and closing of different airways are controlled by independent control valve cores in the corresponding directions.

7. The adaptive control gas protection device for laser additive manufacturing according to claim 6, characterized in that: The control valve core is composed of an electromagnet, a return spring, a connecting shaft and a valve core. The valve core is provided with an air vent parallel to the airway. The valve core and the electromagnet are connected by a connecting shaft, on which a return spring is mounted.

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