Self-adaptive regulation and control gas protection device for laser additive material

Abstract

The invention relates to a self-adaptive regulation and control gas protection device for laser additive materials, and aims to provide efficient inert gas protection so as to reduce oxidation of a molten pool and improve the quality of an additive material layer. According to the device, a protective cover is arranged on a laser cladding head, an air nozzle is connected into the protective cover through a spherical hinge, and inert gas is jetted to form a protective atmosphere. In order to ensure the stability and directivity of airflow, the protective gas disc is connected with the protective cover through a sliding rail, the distance between the protective gas disc and the substrate is adjusted in real time through a distance measuring sensor and a servo motor driving system, and the optimal distance of gas protection is maintained. And meanwhile, four groups of partitioned gas spraying holes and corresponding gas conveying pipes are arranged below the disc, and the gas conveying pipes are connected with a gas electromagnetic valve system, so that the gas spraying area can be automatically adjusted according to the movement direction of the cladding head, dynamic protection on an additive layer is ensured, and oxidation is reduced. And the specially designed hinge sliding block mechanism is linked with the air nozzle, so that the powder flow is prevented from being disturbed by the protective air flow, and stable powder conveying is still kept in the defocusing amount adjusting 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 used in many high value-added fields such as aerospace, automobiles, molds, and medical care in recent years. Laser additive manufacturing, as an important branch, uses laser as a heat source to melt metal powder or wire on the surface of the substrate, and stacks it layer by layer to form the required structure or parts. This process has gradually become an important means of manufacturing and repairing key components because of its advantages such as being able to manufacture complex structures, high material utilization, and shortened manufacturing cycles. However, in the laser additive process, how to effectively control the oxidation of additive parts has always been a difficult problem that affects the quality of additive manufacturing.

[0003] The basic principle of laser additive manufacturing is to heat metal powder with a high-energy laser beam to melt it and form an additive layer on the substrate surface. However, under high temperature conditions, molten metal is very likely to undergo oxidation reactions with oxygen in the environment, resulting in oxide inclusions in the additive layer, which affects the mechanical properties and surface quality of the material. Especially when manufacturing high-demand structural parts or repairing key parts, oxidation problems may lead to embrittlement of the material, a decrease in wear resistance and corrosion resistance, thereby affecting the service life of the entire part.

[0004] In order to solve this problem, it is usually necessary to establish an inert gas protection environment around the molten pool to isolate the oxygen in the air. Common inert gases such as argon or nitrogen can effectively reduce the participation of oxygen and reduce the occurrence of oxidation. However, traditional gas protection methods usually use fixed air nozzles or simple gas hoods for protection. It is impossible to adjust the gas protection in real time according to dynamic working conditions such as the movement path of the laser cladding head, defocus adjustment, and molten pool status, resulting in oxidation risks in local areas.

[0005] During the laser additive manufacturing process, metal powder is accurately delivered to the surface of the molten pool through a powder delivery system. A stable and uniform powder flow is essential for forming a dense and uniform additive layer. However, the traditional gas shielding device may disturb the powder flow and affect the deposition accuracy of the powder because it cannot flexibly adjust the angle of the air nozzle. Once the gas disturbance is too large, it may cause uneven powder dispersion and even fly powder, which seriously affects the final forming quality.

[0006] During the laser additive process, the laser cladding head needs to frequently adjust the defocus according to the process requirements to adapt to different processing requirements. When the defocus is adjusted, the spray direction and airflow intensity of the shielding gas cannot be adjusted synchronously, which can easily disrupt the powder conveying path, making it impossible for the powder to be accurately deposited into the molten pool, thus affecting the material forming effect.

[0007] Traditional laser additive 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 parts;

[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 by the present invention is as follows:

[0013] A self-adjustable gas protection device for laser additive manufacturing comprises an outer cylinder and a cladding head, wherein a laser optical path channel is arranged at 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 oxidizable metal powder; an anti-slip gun body is connected to the bottom of the outer cylinder, and a cladding head is connected to the bottom of the anti-slip gun body, and a protective gas disc is connected to the bottom of the cladding head; 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 a gas pipeline, and the other end of the gas pipeline is connected to the protective gas disc; a plurality of air inlet openings which are in two ways with the gas pipeline are arranged on the protective gas disc, and a group of inert gas pipelines are installed below each air inlet opening, and the plurality of inert gas pipelines are independently controlled by the gas solenoid valve.

[0014] As a further technical solution, the cladding head includes a nozzle, a cladding head shell and a gas shield, the outer platform of the 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 nozzle, and is combined with the cladding head shell to form a chamber, the chamber is communicated with the inert gas channel, and the gas shield area on the lower side of the chamber is provided with square grooves distributed in a circumference, the lower end of the groove is a spherical surface, and a hemispherical hinge is arranged in the groove, and a gas channel is opened in the middle of the hemispherical hinge to form a hemispherical hinge jet pipe with the nozzle; the hemispherical hinge jet pipe is communicated with the chamber and the inert gas channel.

[0015] As a further technical solution, a conical ring is provided inside the thin-walled annular ring at the upper end of the protective gas disc, a hinge is fixedly mounted on the conical ring, the hinge and the slider form a slider hinge structure, and the slider is sleeved on the hemispherical hinge jet pipe of the cladding head.

[0016] As a further technical solution, two 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 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 is composed 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, and an air inlet pipe opening is fixedly installed on the cover plate.

[0018] As a further technical solution, each group of inert gas pipelines is composed of a number of interconnected radial pipelines and circumferential pipelines. A pipeline opening is provided above each group of inert gas pipelines, and the pipeline opening 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 a protective gas disc gas protection path composed of four gas pipelines separated by a gas solenoid valve, and the connected air inlet pipe port, pipeline opening, inert gas pipeline and inert gas nozzle.

[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 arranged 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, and transmit instructions to the driving device after data processing. The driving device 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 hole 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 hole 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 corresponding directions.

[0022] As a further technical solution, the control valve core is composed of an electromagnet, a reset spring, a connecting shaft and a valve core, and 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, and a reset 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 the present invention can intelligently adjust the inert gas injection according to the real-time motion state of the laser cladding head, the change of defocus amount and the processing path, 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, so as to achieve the 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 provided 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, the sensor transmits instructions to the drive device. The drive device drives the shielding gas disc to move up and down. Combined with the real-time feedback from the distance sensor, the shielding gas disc and the additive area are ensured to maintain the set distance range.

[0028] In summary, the dynamic gas protection device of the present invention will significantly improve the quality of laser additive manufacturing, especially in the processing of high value-added parts and complex structural parts, and can effectively reduce oxidation and improve the mechanical properties and surface quality of the finished product. In addition, the intelligent gas control system of the device can reduce the consumption of inert gas, save resources, and improve production economy. With the further promotion of additive manufacturing technology in various industries, the present invention will provide key technical support for the process optimization of laser additive manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0030] Figure 2 A half-section diagram of a gas protection device manufactured by laser additive manufacturing;

[0031] Figure 3 It 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 a hemispherical hinged jet pipe;

[0033] Figure 5 This is a schematic diagram of the protective 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, reset spring; 24, connecting shaft; 25, airway; 26, valve core; 27, valve body; 28, air inlet; 29 chamber; 3, open 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, nozzle; 611, air inlet pipe; 612, inert gas channel; 62, cladding head shell; 63, gas shield; 631, hemispherical hinge jet pipe; 6311, hinge; 6312, slider; 6313, hemispherical hinge; 6314, nozzle; 7, protective gas disc; 71, cover plate; 711, air inlet; 712, buckle; 713, conical ring; 714, slider; 72, disc base; 721, distance sensor; 722, inert gas pipeline; 723, inert gas nozzle; 724, pipeline opening; 8, gas transmission pipe. DETAILED DESCRIPTION

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

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

[0040] In the laser direct energy deposition additive manufacturing process, when using easily oxidizable metal powders (such as titanium, aluminum and their alloys), the molten pool is easily exposed to the air and oxidation problems occur. LDED technology uses a high-energy-density laser beam as a heat source. The high-temperature environment will cause the molten pool to form oxides with oxygen in the air. In addition, the high-temperature additive layer near the molten pool will also react with oxygen. In the subsequent deposition process, the surface oxide will also be remelted and enter the molten pool. The presence of oxides will lead to an increase in inclusions in the microstructure after solidification and reduce the mechanical properties of the material. The coaxial air blowing protection method commonly used in LDED currently has problems such as limited airflow protection range and low gas utilization efficiency. Especially when the scanning speed is fast, the protection effect is more limited. Based on this, the present invention aims to further reduce the risk of molten pool oxidation by forming a relatively closed inert atmosphere zone in the molten pool area, and design a protective gas disc to increase the protection range, thereby providing more effective protection for the high-temperature additive area, and is equipped with a gas solenoid valve to meet the protection requirements under complex paths and reduce inert gas consumption. Finally, combined with the ranging sensor, the gas protection device and the injection hole angle are regulated synchronously based on the change in laser defocus, ensuring the protection effect while avoiding disrupting the powder delivery.

[0041] Combination Figure 1 and Figure 2 As shown, in this embodiment, an improved LDED gas protection device is provided, 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 delivery pipe 8;

[0042] A laser optical path channel is arranged at the center of the outer cylinder 1; a driving device 4 is fixed to the outer ring of the outer cylinder 1 through an open ring 3; the driving device 4 drives the shielding gas disc 7 to move up and down; an anti-slip gun body 5 is connected to the bottom of the outer cylinder 1, a cladding head 6 is connected to the bottom of the anti-slip gun body 5, 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, 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 delivery pipe 11 is fixedly installed on the platform in the middle of the outer cylinder 1, and the powder delivery 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 realize 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, and the threaded interfaces are connected to the robot arm through 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 through screws, and 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, and the open ring 3 is tightened on the outer cylinder 1 by tightening the two threaded holes 31 with bolts; 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 a 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. The T-shaped connecting piece 46 connects the connecting plate 45 and the protective gas disc 7 by screws. The protective gas disc 7 can be moved up and down synchronously 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 by threads, 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 nozzle 61, a cladding head shell 62, and a gas shield 63; the 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 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 nozzle 61 is also fixedly connected to the cladding head shell 62 by screws. After the cladding head shell 62 and the nozzle 61 are fixedly connected, the pores therebetween form an inert gas channel 612, and the upper end of the inert gas channel 612 is communicated with 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, and the conical inner wall of the gas shield 63 is connected to the The outer wall of the nozzle 61 is seamlessly matched and combined with the cladding head shell 62 to form a chamber, which is communicated with 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, and the lower end of the groove is a spherical surface. A hemispherical hinge 6313 is arranged in the groove. A gas channel is opened in the middle of the hemispherical hinge 6313, which forms a hemispherical hinge jet pipe 631 with the nozzle 6314. The hemispherical hinge jet pipe 631 is communicated with the chamber and the inert gas channel 612. During laser additive manufacturing, the inert gas transported 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 jet pipe 631 to form an inert gas atmosphere, thereby protecting the molten pool.

[0047] Furthermore, two 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 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 slider 714 can avoid lateral deviation of the protective gas disc 7 and ensure the stability of movement.

[0048] Furthermore, a conical ring 713 is provided inside the thin-walled annular ring at the upper end of the protective gas disc 7, and a hinge 6311 is fixedly installed on the conical ring 713. The hinge 6311 and the slider 6312 form a slider hinge structure, and the slider 6312 is sleeved on the nozzle 6314 of the hemispherical hinge jet pipe 631. When the protective gas disc 7 moves up and down, the hinge 6311 fixed on the conical ring 713 drives the slider 6312 to slide on the hemispherical hinge jet pipe 631, and the hemispherical hinge jet pipe 631 swings radially under the drive of the slider 6312, changing the angle between the hemispherical hinge jet pipe 631 and the vertical direction, so that the hemispherical hinge jet pipe 631 can adjust the angle synchronously with the movement of the protective 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 protective gas disc 7 is composed of a cover plate 71, a disc base 72 and an inert gas pipeline 722. The cover plate 71 is fixedly connected to the disc base 72 by a buckle 712, and the outer side of the upper end of the cover plate 71 is connected to the driving device 4 by a T-shaped connector 46 and a connecting plate 45. In addition, an air inlet port 711 is fixedly mounted on the cover plate 71, and the air inlet port 711 is connected to the gas solenoid valve 2 through a gas delivery pipe 8 to control the supply of the inert gas. In this embodiment, the inert gas pipeline 722 is installed in the chamber of the protective gas disc 7, and is divided into four groups, which are respectively located at the "front", "rear", "left" and "right" positions of the protective gas disc 7. Each group of inert gas pipelines is composed of a number of interlinked radial pipelines and circumferential pipelines. A pipeline opening 724 is provided above each group of inert gas pipelines 722, and the pipeline opening 724 is connected to the air inlet port 711. At the same time, the bottom of the inert gas pipeline 722 is connected to the inert gas nozzle 723 on the disc base 72, forming a gas protection path of the protective gas disc 7 composed of four gas pipelines 8 separated by the gas solenoid valve 2, the connected air inlet port 711, the pipeline opening 724, the inert gas pipeline 722 and the inert gas nozzle 723. It should be noted that the inert gas pipeline 722 is not limited to the four groups of "front", "rear", "left" and "right" given in this embodiment, and five groups, six groups, seven groups, etc. can also be set, and multiple groups of inert gas pipelines 722 can be evenly distributed along the circumference of the protective 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 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 whether one chamber 29 is connected to 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 part of the air inlet hole is connected to four chambers 29 in the gas solenoid valve 2, and the four chambers are connected to the airways 25 corresponding to the "front", "rear", "left" and "right" directions respectively, and 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 through the 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 laser additive manufacturing is performed, a scanning path is set, and when the scanning path is a straight path, the corresponding "back", "front", "right" and "left" directional electromagnet 22 power-on instructions are deduced based on the "front", "back", "left" and "right" movement data of the scanning path, and the corresponding "back", "front", "right" and "left" directional electromagnet 22 is powered on to make the valve core 26 move along the connecting shaft 24, and the vent hole on the valve core 26 is in line with the airway 25 to allow the inert gas to flow and be transported to the protective gas through the gas pipe 8. The gas shielding disc 7 makes the inert gas nozzles 723 at the "rear", "front", "right" and "left" positions spray gas. In addition, when the scanning path direction changes, for example, after the scanning direction changes from "front" to "right", the electromagnet 22 at the previous "rear" position is powered off, the valve core 26 is reset under the action of the reset spring 23, the airway 25 is closed again, and the inert gas nozzle 723 at the "rear" position of the protective gas disc 7 no longer sprays, but the inert gas nozzle 723 at the "left" position starts to spray protection. The above process is realized under a straight scanning path, the molten pool is in a semi-closed inert gas atmosphere formed by the gas shield 63, and the high-temperature additive area at the rear is always in the inert protective atmosphere formed by the protective gas disc 7, so as to greatly reduce the oxidation degree of the easily oxidized area and improve the performance of the additive parts. At the same time, no protective gas will be sprayed out from other positions of the molten pool, which saves inert gas and improves the utilization rate of the inert gas. When the scanning path is a complex curve, the computer analyzes and deduce the program to simultaneously control multiple solenoid valves 22 to be energized, so that one or more groups of inert gas nozzles 723 can be sprayed to protect the additive parts under the complex path. In addition, dynamic airflow control can be achieved, that is, the protective gas device can automatically adjust the direction and intensity of the inert gas airflow according to the movement state of the cladding head, path changes and environmental parameters to ensure that the inert gas covers the high-temperature molten pool to form all-round protection; through the precise control of the gas distribution system, according to the movement trajectory of the cladding head, the gas injection area is reasonably allocated to achieve the optimal utilization of gas resources, reduce gas waste, and reduce 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 protective gas disc 7 to prevent the protective gas disc 7 from being overheated and damaging the gas protection 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 of 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 protection device designed for the above-mentioned laser cladding additive manufacturing is intended to provide efficient inert gas protection to reduce the oxidation of the molten pool and improve the quality of the additive layer. The device sets a shield on the laser cladding head, and the inside of the shield is connected to a short-tube air nozzle through a spherical hinge to spray inert gas to form a protective atmosphere. To ensure the stability and directionality of the airflow, the protective gas disc is connected to the shield through a slide rail, and the distance between the disc and the substrate is adjusted in real time through the rangefinder and the servo motor control system to maintain the optimal spacing of the gas protection layer. At the same time, four groups of partitioning holes and corresponding air pipes are provided under the disc. These air pipes are connected to the electromagnetic control system, which can automatically adjust the area of ​​gas injection 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 can be maintained during the defocus adjustment process.

[0056] The present invention is used in the laser cladding additive manufacturing process, and is particularly suitable for inert gas protection of the molten pool and high-temperature additive layer. By dynamically adjusting the gas injection direction and optimizing the airflow control, it can effectively reduce the oxidation reaction, improve the stability and surface quality of the additive process, and is particularly suitable for the manufacture of large, high-value-added parts. The device solves the problems of oxidation and airflow disturbance of powder in traditional laser additive manufacturing, improves process accuracy and efficiency, has broad industrial application prospects, and promotes technological progress in the field of additive manufacturing.

Claims

1. An adaptively controlled gas protection device for laser additive manufacturing, comprising an outer cylinder and a cladding head, wherein a laser optical path is provided at the center of the outer cylinder; a powder delivery pipe is fixedly installed on a platform in the middle of the outer cylinder, and the powder delivery pipe is used to deliver easily oxidizable metal powder, characterized in that: An anti-slip gun body is connected to the bottom of the outer cylinder, a cladding head is connected to the bottom of the anti-slip gun body, a protective gas disc is connected to the bottom of the cladding head, a driving device and a gas solenoid valve are fixed to the outer ring of the outer cylinder, 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, the other end of the gas pipe is connected to the protective gas disc, a plurality of air inlet ports that are in communication with the gas pipe are arranged on the protective gas disc, a group of inert gas pipelines are installed under each air inlet port, and the plurality of inert gas pipelines are independently controlled by the gas solenoid valve.

2. The adaptive control gas protection device for laser material addition according to claim 1, characterized in that: The cladding head comprises a nozzle, a cladding head shell and a gas shield, the outer platform of the 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 nozzle, and is combined with the cladding head shell to form a chamber, the chamber is communicated with the inert gas channel, and the gas shield area on the lower side of the chamber is provided with square grooves distributed in a circumference, the lower end of the groove is a spherical surface, a hemispherical hinge is arranged in the groove, a gas channel is provided in the middle of the hemispherical hinge, and a hemispherical hinge jet pipe is formed with the nozzle; the hemispherical hinge jet pipe is communicated with the chamber and the inert gas channel.

3. The adaptive control gas protection device for laser material addition according to claim 2, characterized in that: A conical ring is arranged inside the thin-walled annular ring at the upper end of the protective gas disc, a hinge is fixedly mounted on the conical ring, the hinge and the slider form a slider hinge structure, and the slider is sleeved on the hemispherical hinge jet pipe of the cladding head.

4. The adaptive control gas protection device for laser material addition according to claim 1, characterized in that: Two 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.

5. The adaptive control gas protection device for laser material addition according to claim 1, characterized in that: The protective gas disc is composed 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. An air inlet port is fixedly installed on the cover plate.

6. The adaptive control gas protection device for laser material addition according to claim 5, characterized in that: Each group of inert gas pipelines is composed of a number of interconnected radial pipelines and circumferential pipelines. A pipeline opening is provided above each group of inert gas pipelines, and the pipeline opening 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 a protective gas disc gas protection path composed of four gas pipelines separated by a gas solenoid valve, the connected air inlet pipe port, the pipeline opening, the inert gas pipeline and the inert gas nozzle.

7. The adaptive control gas protection device for laser material addition according to claim 5, characterized in that: A water cooling pipe is arranged above the disc base, and the water cooling pipe is used to cool down and protect the protective gas disc.

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

9. The adaptive control gas protection device for laser material addition according to claim 1, characterized in that: The gas solenoid valve includes a valve body and multiple control valve cores; an air inlet hole 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 hole 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 corresponding directions.

10. The adaptive control gas protection device for laser material addition according to claim 9, characterized in that: The control valve core is composed of an electromagnet, a reset 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 through a connecting shaft, and a reset spring is mounted on the connecting shaft.

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