Atmosphere-controllable overhead online powder supply powder bed additive manufacturing equipment

Abstract

The invention discloses atmosphere-controllable top-mounted online powder supply powder bed additive manufacturing equipment. The equipment is free of a powder cylinder, comprises a powder melting or bonding working head, an x-y scanning system, a working box, a forming cylinder, a powder laying mechanism, a platform and a control system, and also adopts a top-mounted online powder recycling and feeding system to recycle and process overflowing powder on line and feed powder required by each layer to a powder bed on line in real time; smoke dust in a working cavity is removed by adopting a gas circulating filtration system, and the atmosphere in the cavity is purified; a working cavity is sealed, and a gas detection and replacement system is adopted for online monitoring and real-time adjustment of gas components and pressure in the working cavity; an atmosphere temperature measurement and control system is adopted to monitor the atmosphere temperature in the working cavity on line, water cooling is conducted timely, and the atmosphere temperature is adjusted. The device has the beneficial effects that the powder utilization rate is increased, the stability of the additive manufacturing process is improved, process interruption is avoided, the forming quality is ensured, powder combustion and explosion are prevented, the machine structure is compact, and parts are precisely matched.

Description

Technical Field

[0001] The present invention relates to a forming manufacturing device, in particular to a powder bed additive manufacturing device. Background Art

[0002] Additive manufacturing is considered to be a promising manufacturing method and is receiving widespread attention at home and abroad. More and more additive manufacturing methods and equipment have been developed. Among them, the powder bed additive manufacturing processes such as powder bed fusion and powder bed inkjet have high dimensional accuracy and complex structure of the parts formed. Therefore, the powder bed additive manufacturing process is more popular. Therefore, the powder bed additive manufacturing process has a good development momentum.

[0003] In the powder bed additive manufacturing process, before each layer of a part or model is formed, a layer of powder of appropriate thickness needs to be laid on the powder bed in advance. The powder is supplied by a powder supply mechanism. In the past, the powder supply mechanism was one or two powder supply cylinders. Before additive manufacturing, the powder supply cylinders were filled with powder; during the additive manufacturing process, before laying each layer of powder, the powder supply cylinder was raised to a height so that the upper surface of the powder was higher than the work surface, so that the powder laying device could scrape the powder onto the forming working cylinder. This powder supply method has several disadvantages: 1) One or two powder supply cylinders and the scraping area above them occupy a large space, which not only makes the machine bulky, but also is not conducive to oxygen isolation in the cavity; 2) The powder needs to fill the powder supply cylinder before each forming, so that the forming of small components also requires more powder; 3) Powder cannot be added to the powder cylinder online; 4) Components with gradient materials cannot be formed.

[0004] In addition, during the additive manufacturing process, the atmosphere in the working chamber has a huge impact on the forming and quality of the parts. For example, during the metal additive manufacturing process, oxygen will oxidize the metal to form metal oxide particles, which is not conducive to metal forming, and will form oxidized slag in the parts, which will deteriorate the performance of the parts; in the powder bed additive manufacturing process that uses a laser beam to melt the powder, the smoke and dust generated by the interaction between the laser and the powder in the working chamber will contaminate the laser projection lens; in addition, if the temperature of the atmosphere in the chamber is too high, it will increase the risk of combustion or even explosion of the powder in the chamber, and cause the temperature of the chamber to rise, the size of related parts to change, and reduce the matching accuracy. Therefore, the atmosphere in the working chamber must be regulated in real time. Summary of the invention

[0005] In order to solve the above problems, the present invention provides an atmosphere-controllable top-mounted online powder-feeding powder bed additive manufacturing equipment.

[0006] The solution to the problem provided by the present invention is as follows: in addition to comprising a powder melting high-energy beam or powder bonding work head, an xy scanning system, a work box, a forming cylinder, a powder spreading mechanism, a powder spreading platform, and a control system, the powder bed additive manufacturing equipment also adopts an upper-mounted online powder recovery and supply system to recover and process the powder overflowed during the additive manufacturing process online, and can supply recovered powder or new powder to the powder bed online and in real time according to the needs of each layer of the formed component, to ensure the appropriate type and amount of powder required for forming each layer, and to make the equipment structure compact without the need for a powder cylinder parallel to the forming cylinder; a gas circulation filtration system is adopted to remove smoke and dust generated in the working chamber during the additive manufacturing process and purify the atmosphere in the chamber; a gas detection and replacement system is adopted to monitor the gas composition and pressure in the working chamber online, adjust the gas composition in the working chamber in real time and maintain the appropriate gas pressure in the working chamber; an atmosphere temperature measurement and control system is adopted to monitor the atmosphere temperature in the working chamber online, start and stop the cooling function in time, and adjust the atmosphere temperature in the chamber; a sealed working chamber is formed, which is conducive to extracting the gas in the chamber, blocking air from penetrating into the chamber, and maintaining a suitable atmosphere in the chamber.

[0007] The above-mentioned atmosphere-controllable top-mounted online powder supply powder bed additive manufacturing equipment, the sealed working chamber is surrounded by a working box, a powder spreading platform, and a forming cylinder, forming a working space where powder is spread layer by layer in the powder bed and melted or bonded by 3D scanning. The side wall of the working box is connected to the pipelines of the gas circulation filtration system and the gas detection and replacement system for regulating the internal atmosphere, and is assembled and connected to the top-mounted online powder recovery and supply system on the powder spreading platform and the top of the working box. The various pipelines connected to the cavity and their electrically controlled valves have high air tightness, and each pipeline interface adopts a sealing ring or a sealing raw material tape, and each assembly surface surrounding the cavity adopts a sealing gasket or a sealing ring to achieve the sealing of the working chamber, facilitate the extraction of the gas in the cavity, block the air from penetrating into the cavity, and maintain a suitable atmosphere in the cavity.

[0008] The above-mentioned atmosphere-controllable top-mounted online powder feeding powder bed additive manufacturing equipment, the gas circulation filtration system is composed of a gas circulation pipeline, an electric control valve, a gas filter and a gas circulation pump, which together with the working box form a gas circulation flow channel. At the beginning of the additive manufacturing process, the computer sends a command to the control system to automatically open the electric control valve and start the gas circulation pump. The gas in the working chamber carries smoke and dust and forms an airflow, which enters the gas filter through the gas circulation pipe. The airflow is filtered, and the smoke and dust carried are filtered out. The filtered airflow passes through the gas circulation pump and the gas circulation pipe and returns to the working chamber to continuously purify the atmosphere in the chamber.

[0009] The above-mentioned atmosphere-controllable top-mounted online powder supply powder bed additive manufacturing equipment, the gas detection and replacement system is composed of a vacuum pump, a vacuum pipeline and its electric control valve, a protective gas pipeline and its electric control valve, a one-way valve, a pressure detector, a gas composition detector, and a gas composition sampling electric control valve. The protective gas pipeline is connected to the protective gas source, and the protective gas is supplied to the working chamber through the electric control valve to change the gas composition in the chamber and increase the atmosphere pressure in the chamber; the vacuum pipeline is connected to the vacuum pump, and when the electric control valve is opened and the vacuum pump is working, the chamber is vacuumed to reduce the gas in the chamber and reduce the atmosphere pressure in the chamber; the one-way valve automatically discharges the gas in the chamber when the lens protective gas continues to enter the working chamber and causes the pressure to be too high, so as to prevent the pressure in the chamber from continuing to rise; the pressure detector and the gas composition detector detect the gas pressure and composition in the chamber respectively, and the computer sends instructions to the control system to control the switch of the electric control valve, the start and stop of the vacuum pump, and the supply of protective gas based on the real-time detection data, so as to regulate the atmosphere pressure and composition in the working chamber.

[0010] The above-mentioned atmosphere-controllable top-mounted online powder supply powder bed additive manufacturing equipment, for additive manufacturing processes that require inert gas protection, before additive manufacturing forming, close the protective gas pipeline electric control valve, open the vacuum pipeline electric control valve, start the vacuum pump, and use the vacuum pump to evacuate the working chamber until the pressure detector shows that the working chamber has reached a suitable vacuum degree, then close the vacuum pump and the vacuum pipeline electric control valve, connect the protective gas source, open the protective gas pipeline electric control valve, fill in inert gas, until the gas pressure in the working chamber forms a slight positive pressure regulated by a one-way valve relative to the air outside the chamber, so as to prevent the air outside the chamber from infiltrating into the chamber and increasing the oxygen content, close the protective gas pipeline electric control valve, and maintain the lens protective gas delivery; if the atmosphere detector detects and shows that the oxygen content in the working chamber is too high, the additive manufacturing forming process is first suspended. Scanning, lifting and lowering of the forming cylinder piston, powder supply and powder spreading, etc., close the electronic control valves of all air inlet pipes, open the electronic control valves of the vacuum pipeline, start the vacuum pump, and after a certain amount of gas in the cavity is pumped out, stop the vacuum pump, close the electronic control valve of the vacuum pipeline, open the air inlet pipe, and fill with inert gas. Repeat this process until the oxygen content in the working chamber meets the process requirements.

[0011] The above-mentioned atmosphere-controllable top-mounted online powder supply powder bed additive manufacturing equipment, the atmosphere temperature measurement and control system is composed of a temperature detector, a cooling water circuit and its electric control valve, a water cooling jacket and a water chiller. The temperature detector detects the atmosphere temperature in the working chamber, the water chiller provides cooling water to the water cooling jacket through the cooling water circuit and the electric control valve, and the gas circulation pipeline passes through the water cooling jacket. During the additive manufacturing process, the computer determines whether the control system opens the electric control valve and allows cooling water to enter the water cooling jacket to cool the circulating gas in the gas circulation pipeline based on whether the detected temperature data exceeds the set value. The cooled circulating gas returns to the working chamber to cool the gas, powder and inner wall of the working chamber, thereby reducing the atmosphere temperature in the chamber to a suitable temperature range.

[0012] The above-mentioned atmosphere-controllable top-mounted online powder supply powder bed additive manufacturing equipment, the top-mounted online powder recovery and supply system is composed of a powder screening and supplying machine, a powder conveying pipeline, an top-mounted quantitative powder feeding mechanism, an overflow trough, an overflow collection hopper, a manual ball valve, a powder storage tank, and an electric control valve for the powder conveying pipeline. The powder conveying pipeline and the electric control valve between the powder screening and supplying machine and the top-mounted quantitative powder feeding mechanism constitute a powder supply channel, which starts from the front and rear overflow troughs on the powder spreading platform and respectively passes through the overflow collection hopper, the manual ball valve, the powder storage tank, and the electric control valve to converge into a powder conveying pipeline, and then the channel to the powder screening and supplying machine is the powder recovery channel.

[0013] In the above-mentioned top-mounted online powder recovery and supply system, the powder screening and supplying machine can suck powder from the powder recovery channel and blow powder into the powder supply channel. The computer can command the control system to open the electric control valve on the powder supply channel, control the powder screening and supplying machine to convey the stored powder by air to the top-mounted quantitative powder feeding mechanism through the conveying pipeline, and can also open the electric control valve on the powder recovery channel, control the powder screening and supplying machine to convey the overflowed powder by air through the conveying pipeline for screening and storage.

[0014] The above-mentioned top-mounted online powder recovery and supply system, the top-mounted quantitative powder feeding mechanism is composed of a powder bin, a powder bin supporting shaft, a powder remaining amount monitoring device in the powder bin, a quantitative powder feeding motor drive system, and an impeller shaft quantitative powder feeding body. It is suspended on the working box suspension beam through the powder bin top flange and the powder bin supporting shaft. The computer calculates the powder demand according to the thickness and area of ​​the powder layer to be scanned, and sets the rotation angle of the quantitative powder feeding impeller shaft, and sends instructions to the control system to control the quantitative powder feeding motor drive system to drive the quantitative powder feeding impeller shaft to rotate to the set angle. The quantitative powder in the powder bin falls into the powder spreading mechanism located directly below the impeller shaft quantitative powder feeding body, and the powder spreading mechanism spreads a layer of powder on the surface of the powder bed.

[0015] In the above-mentioned upper-mounted online powder recovery and supply system, the powder residue monitoring device in the powder silo monitors the powder residue and stacking flatness in the silo online during the additive manufacturing process. The computer promptly sends instructions to the control system based on the requirements of part additive manufacturing and the real-time monitored powder residue and stacking flatness in the silo, and controls the powder screening and supplying machine and the powder supply channel electric control valve to transport powder to the upper-mounted quantitative powder feeding mechanism.

[0016] The beneficial effects of implementing the present invention are that it can avoid interruption of the additive manufacturing process caused by inaccurate powder quantity measurement, continuously form components of different sizes, and improve powder utilization. At the same time, the machine structure is compact due to the lack of a powder cylinder; the temperature, composition and pressure of the atmosphere in the working chamber are regulated, smoke and dust are removed, the forming quality and the stability of the forming process are ensured, powder combustion and explosion are prevented, and high-temperature deformation of the cavity and parts in the cavity is avoided, and the sealing of the working chamber and the precise fit between parts are maintained. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Front view of the laser beam powder bed fusion additive manufacturing equipment with top-mounted online powder supply and controlled atmosphere.

[0018] Figure 2 Left view of the mainframe of the atmosphere-controlled top-mounted laser beam powder bed fusion additive manufacturing equipment with online powder supply.

[0019] Figure 3 Schematic diagram of the control of the laser beam powder bed fusion additive manufacturing equipment with top-mounted online powder supply and controlled atmosphere.

[0020] In the figure, 1. Powder screening and feeding machine, 1-0. Powder screening and feeding machine start and stop relay, 2. Powder conveying pipeline, 2-1. Overflow collection hopper, 2-2. Manual ball valve, 2-3. Powder storage tank, 2-4. Powder conveying electric control valve, 2-4-1. Powder supply channel electric control valve 1, 2-4-1-0. Powder supply channel electric control valve relay 1, 2-4-2. Powder supply channel electric control valve 2, 2-4-2-0. Powder supply channel electric control valve relay 2, 2-4-3 .Powder recovery channel electric control valve 1, 2-4-3-0.Powder recovery channel electric control valve relay 1, 2-4-4.Powder recovery channel electric control valve 2, 2-4-4-0.Powder recovery channel electric control valve relay 2, 3.Working box, 3-1.Working box suspension beam, 4.Top-mounted quantitative powder feeding mechanism, 4-1.Quantitative powder feeding motor drive system, 4-1-1.Quantitative powder feeding motor, 4-1-1-0.Quantitative powder feeding motor driver, 4-2. Impeller shaft quantitatively feeds powder, 4-3. Powder bin, 4-4. Powder bin support shaft, 4-5. Powder residue monitoring device in powder bin, 5. Vibrating mirror system, 5-1. Lens gas protection device, 5-2. Lens protection gas pipeline, 5-3. Lens protection gas flow meter, 5-4. Lens protection gas electric control valve, 5-4-0. Lens protection gas electric control valve relay, 6. Collimating beam expander, 7. Powder spreading mechanism, 7-1. Groove-type powder spreading body, 7-2. Powder spreading guide Rail pair, 7-3. Powder spreading motor drive system, 7-3-1. Powder spreading motor, 7-3-1-0. Powder spreading motor driver, 8. Temperature detector, 9. Protective gas pipeline, 9-1. Protective gas pipeline electric control valve, 9-1-0. Protective gas pipeline electric control valve relay, 10. Pressure detector, 11. Gas composition detector, 11-1. Gas composition detection sampling electric control valve, 11-1-0. Gas composition detection sampling electric control valve relay, 11-2. Gas composition detection sampling pipeline, 12. Vacuum pipeline, 12-1. Vacuum pipeline electric control valve, 12-1-0. Vacuum pipeline electric control valve relay, 12-2. Vacuum pump, 12-2-0. Vacuum pump start-stop relay, 13. Computer, 14. Water cooling jacket, 14-1. Cooling water electric control valve, 14-1-0. Cooling water electric control valve relay, 15. Laser, 15-0. Laser start-stop relay, 15-1. Laser transmission optical fiber , 16. Gas circulation pipeline, 16-1. Gas circulation pipeline electric control valve, 16-1-0. Gas circulation pipeline electric control valve relay, 16-1-1. Gas outlet electric control valve, 16-1-2. Gas return electric control valve, 16-2. Gas circulation pump, 16-2-0. Gas circulation pump start-stop relay, 16-3. Gas filter, 17. Water cooler, 17-0. Water cooler start-stop relay, 18. Forming cylinder, 18-1. Z-axis motor in forming cylinder, 18-1-0. Z-axis motor driver in forming cylinder, 19. Powder spreading platform, 20. One-way valve, 21. Control module, 22. Electrical board, 22-1. Weak current load relay group, 22-2.High current load relay group, 22-3. Motor driver group. . Implementation

[0021] Taking the atmosphere-controllable top-mounted online powder supply laser beam metal powder bed fusion additive manufacturing equipment as an example, the powder bed additive manufacturing equipment includes not only the optical fiber transmission laser 15, the galvanometer system 5, the water cooler 17, the work box 3, the forming cylinder 18, the powder spreading mechanism 7, the powder spreading platform 19, and the control system, but also includes a top-mounted online powder recovery and supply system, a gas detection and replacement system, a gas circulation and filtration system, and an atmosphere temperature measurement and control system, and forms a sealed working chamber, which can recover powder from and add powder to the working chamber online and in real time, monitor and control the gas pressure, composition and temperature in the working chamber online and in real time, and purify the atmosphere in the chamber.

[0022] The sealed working chamber is surrounded by a working box 3, a powder spreading platform 19, and a forming cylinder 18. The side wall of the working box 3 is connected to the gas circulation pipeline 16 of the gas circulation filtration system, the protective gas pipeline 9 and the vacuum pipeline 12 of the gas detection and replacement system, as well as the lens protection gas pipeline 5-2 and the gas composition detection sampling pipeline 11-2. The top of the powder spreading platform 19 and the working box 3 is assembled and connected with the upper online powder recovery and supply system. The various pipelines connected to the cavity and their electric control valves have high air tightness. Each pipeline interface adopts a sealing ring or a sealing raw material tape, and each assembly surface surrounding the cavity adopts a sealing gasket or a sealing ring.

[0023] The gas circulation filtration system is composed of a gas circulation pipeline 16, a gas circulation pipeline electric control valve 16-1, a gas filter 16-3 and a gas circulation pump 16-2, which form a gas circulation flow channel with the working box 3. When the additive manufacturing process starts, the computer 13 sends a command to the control module 21, so that the relay 16-1-0 opens the gas circulation pipeline electric control valve 16-1 and the relay 16-2-0 opens the gas circulation pump 16-2. The gas in the working chamber carries smoke and dust and forms an airflow, which enters the gas filter 16-3 through the gas circulation pipeline 16. The airflow is filtered, and the smoke and dust carried are filtered out. The filtered airflow passes through the gas circulation pump 16-2 and the gas circulation pipeline 16 and returns to the working chamber to continuously purify the atmosphere in the chamber.

[0024] The gas detection and replacement system consists of a vacuum pump 12-2, a vacuum pumping line 12 and its electric control valve 12-1, a protective gas pipeline 9 and its electric control valve 9-1, a one-way valve 20, a pressure detector 10, a gas composition detector 11, and a gas composition sampling electric control valve 11-1. The protective gas pipeline 9 is connected to the protective gas source, and provides protective gas to the working chamber through the electric control valve 12-1, changing the gas composition in the chamber and increasing the atmosphere pressure in the chamber; the vacuum pumping line 12 is connected to the vacuum pump 12-2, and when the electric control valve 12-1 is opened and the vacuum pump 12-2 is working, the chamber is evacuated to reduce the gas in the chamber and reduce the atmosphere pressure in the chamber; when the protective gas from the lens gas protection device 5-1 continues to enter the working chamber and causes the pressure to be too high, the one-way valve 20 automatically discharges the gas in the chamber to prevent the pressure in the chamber from continuing to rise. The pressure detector 10 and the gas composition detector 11 detect the gas pressure and composition in the cavity respectively. The computer 13 issues instructions to the control module 21 according to the real-time detection data, and sends control signals to the relays 12-1-0 and 9-1-0 on the electrical board 22 to control the switches of the vacuum pipeline electric control valve 12-1 and the protective gas pipeline electric control valve 9-1 respectively. It also sends signals to the relay 12-2-0 on the electrical board 22 to control the start and stop of the vacuum pump 12-2, so as to regulate the atmosphere pressure and composition in the working chamber.

[0025] Before the additive manufacturing of metal parts, close the protective gas pipeline electric control valve 9-1, open the vacuum pipeline electric control valve 12-1, start the vacuum pump 12-2, and use the vacuum pump 12-2 to evacuate the working chamber until the pressure detector 10 shows that the working chamber has reached a suitable vacuum degree, then close the vacuum pump 12-2 and the vacuum pipeline electric control valve 12-1, connect the protective gas source, open the protective gas pipeline electric control valve 9-1, fill with inert gas, until the gas pressure in the working chamber forms a slight positive pressure regulated by the one-way valve relative to the air outside the chamber, and maintain the blowing protection of the lens protective gas device 5-1; if If the gas composition detector 11 detects and displays that the oxygen content in the working chamber is too high, the operation of the additive manufacturing galvanometer system 5, the forming cylinder 18, the upper type quantitative powder feeding mechanism 4 and the powder spreading mechanism 7 are first suspended, and the electric control valves 5-4 and 9-1 of all the air inlet pipes are closed, the electric control valve 12-1 of the vacuum pipeline is opened, and the vacuum pump 12-1 is started. After a certain amount of gas in the chamber is pumped away, the vacuum pump 12-1 is stopped, the electric control valve 12-1 of the vacuum pipeline is closed, and the electric control valves 5-4 and 9-1 of the air inlet pipe are opened to fill in inert gas. The vacuuming and filling are repeated until the oxygen content in the working chamber meets the process requirements.

[0026] The atmosphere temperature measurement and control system is composed of a temperature detector 8, a cooling water circuit 14-2, a cooling water electric control valve 14-1, a water cooling jacket 14 and a water chiller 17. The temperature detector 8 detects the atmosphere temperature in the working chamber, the water chiller 17 provides cooling water to the water cooling jacket 14 through the cooling water circuit 14-2 and the cooling water electric control valve 14-1, and the gas circulation pipeline 16 passes through the water cooling jacket 14. During the additive manufacturing process, the computer 13 determines whether the control module 21 sends a signal to the relay 14-1-0 on the electrical board 22 to open the cooling water electric control valve 14-1 and allow cooling water to enter the water cooling jacket 14 to cool the circulating gas in the gas circulation pipeline 16 according to whether the detected temperature data exceeds the set value. The cooled circulating gas returns to the working chamber to cool the gas, powder and inner wall of the working chamber, thereby reducing the atmosphere temperature in the chamber to a suitable temperature range.

[0027] The upper-mounted online powder recovery and supply system consists of a powder screening and supplying machine 1, a powder conveying pipeline 2, an upper-mounted quantitative powder feeding mechanism 4, front and rear overflow troughs of a powder spreading platform 19, an overflow collecting hopper 2-1, a manual ball valve 2-2, a powder storage tank 2-3, and a powder conveying electric control valve 2-4. The powder conveying pipeline 2, the powder conveying electric control valves 2-4-1 and 2-4-2 between the powder screening and supplying machine 1 and the upper-mounted quantitative powder feeding mechanism 4 constitute a powder supply channel, which starts from the front and rear overflow troughs on the powder spreading platform 9 and respectively passes through the overflow collecting hopper 2-1, the manual ball valve 2-2, the powder storage tank 2-3, the powder conveying electric control valves 2-4-3 and 2-4-4 to converge into a powder conveying pipeline 2, and then the channel to the powder screening and supplying machine 1 is a powder recovery channel.

[0028] The powder screening and feeding machine 1 can suck powder from the powder recovery channel and blow powder to the powder supply channel. The computer 13 can command the control module 21 to make the relays 2-4-1-0 and 2-4-2-0 on the electrical board 22 open the electric control valves 2-4-1 and 2-4-2 on the powder supply channel, and the relay 1-0 to open the powder screening and feeding machine 1 to convey the stored powder to the upper quantitative powder feeding mechanism 4 through the powder conveying pipeline 2 by air; the relays 2-4-3-0 and 2-4-4-0 on the electrical board 22 can also open the electric control valves 2-4-3 and 2-4-4 on the powder recovery channel, and the relay 1-0 on the electrical board 22 to open the powder screening and feeding machine 1 to convey the overflowed powder by air through the conveying pipeline 2 for screening and storage.

[0029] The upper type quantitative powder feeding mechanism 4 is composed of a powder bin 4-3, a powder bin support shaft 4-4, a powder remaining amount monitoring device 4-5 in the powder bin, a quantitative powder feeding motor drive system 4-1, and an impeller shaft quantitative powder feeding body 4-2. The impeller shaft quantitative powder feeding body 4-2 is suspended on the working box suspension beam 3-1 through the top flange of the powder bin 4-3 and the powder bin support shaft 4-4. The impeller shaft quantitative powder feeding body 4-2 is fixed and connected to the bottom of the powder bin 4-3. The computer 13 calculates the powder demand according to the thickness and area of ​​the powder layer to be scanned, and sets the rotation angle of the impeller shaft of the impeller shaft quantitative powder feeding body 4-2, and sends a command to the control module 21 to make the electrical board 2 The driver 4-1-0 on 2 controls the quantitative powder feeding motor driving system 4-1 to drive the impeller shaft quantitative powder feeding body 4-2 to rotate a set angle, and the quantitative powder in the powder bin 4-3 falls into the trough type powder spreading body 7-1 of the powder spreading mechanism 7 located directly below the impeller shaft quantitative powder feeding body 4-2. After the driver 7-3-1-0 receives the control signal of the control module 21, it drives the powder spreading motor 7-3-1 of the powder spreading motor driving system 7-3 to work, and the trough type powder spreading body 7-1 performs powder spreading movement on the powder spreading platform 19 under the guidance of the powder spreading guide rail pair 7-2, spreads and adds an appropriate amount of powder on the surface of the powder bed.

[0030] The powder residue monitoring device 4-5 in the powder bin monitors the powder residue and stacking flatness in the powder bin 4-3 online during the additive manufacturing process. The computer 13 sends instructions to the control module 21 in time according to the requirements of part additive manufacturing and the real-time monitored powder residue and stacking flatness in the powder bin 4-3, so that the relay 1-0 starts the powder screening and feeding machine 1, and the relays 2-4-1-0 and / or 2-4-2-0 respectively open the powder conveying electric control valves 2-4-1 and / or 2-4-2 on the powder supply channel to convey powder to the upward quantitative powder feeding mechanism 4.

Claims

1. An atmosphere-controllable top-mounted online powder feeding powder bed additive manufacturing equipment system, characterized in that: In addition to including a powder melting high-energy beam or powder bonding work head, an xy scanning system, a work box, a forming cylinder, a powder spreading mechanism, a powder spreading platform, and a control system, the powder bed additive manufacturing equipment also adopts an upper-mounted online powder recovery and supply system to online recover and process the powder overflowed during the additive manufacturing process, and can supply recovered powder or new powder to the powder bed online in real time according to the needs of each layer of the formed component, to ensure the appropriate type and quantity of powder required for forming each layer, and there is no need for a powder cylinder parallel to the forming cylinder, making the equipment structure compact; a gas circulation filtration system is used to remove smoke and dust generated in the working chamber during the additive manufacturing process and purify the atmosphere in the chamber; a gas detection and replacement system is used to online monitor the gas composition and pressure in the working chamber, adjust the gas composition in the working chamber in real time and maintain a suitable gas pressure in the working chamber; an atmosphere temperature measurement and control system is used to online monitor the atmosphere temperature in the working chamber, start and stop the cooling function in time, and adjust the atmosphere temperature in the chamber; a sealed working chamber is formed, which is conducive to extracting the gas in the chamber, blocking air from penetrating into the chamber, and maintaining a suitable atmosphere in the chamber.

2. The atmosphere-controlled top-mounted online powder-feeding powder bed additive manufacturing equipment according to claim 1 is also characterized by: The sealed working chamber is surrounded by a working box, a powder spreading platform, and a forming cylinder, forming a working space where powder is spread layer by layer in a powder bed and melted or bonded by 3D scanning. The side wall of the working box is connected to the pipelines of a gas circulation and filtration system for regulating the internal atmosphere and a gas detection and replacement system. The powder spreading platform and the top of the working box are assembled and connected to an upper-mounted online powder recovery and supply system. The pipelines connected to the cavity and their electrically controlled valves have high air tightness. Sealing rings or sealing raw material tapes are used on each pipeline interface, and sealing pads or sealing rings are used on each assembly surface that surrounds the cavity to achieve sealing of the working chamber, facilitate extraction of gas in the cavity, prevent air from infiltrating into the cavity, and maintain a suitable atmosphere in the cavity.

3. The atmosphere-controlled top-mounted online powder-feeding powder bed additive manufacturing equipment according to claim 1 is also characterized by: The gas circulation filtration system is composed of a gas circulation pipeline, an electric control valve, a gas filter and a gas circulation pump, which together with the working box form a gas circulation flow channel. When the additive manufacturing process begins, the computer sends a command to the control system to automatically open the electric control valve and start the gas circulation pump. The gas in the working chamber carries smoke and dust and forms an airflow, which enters the gas filter through the gas circulation pipe. The airflow is filtered, and the smoke and dust carried are filtered out. The filtered airflow passes through the gas circulation pump and the gas circulation pipe and returns to the working chamber to continuously purify the atmosphere in the chamber.

4. The atmosphere-controlled top-mounted online powder-feeding powder bed additive manufacturing equipment according to claim 1 is also characterized by: The gas detection and replacement system is composed of a vacuum pump, a vacuum pumping pipeline and its electric control valve, a protective gas pipeline and its electric control valve, a one-way valve, a pressure detector, a gas composition detector, and a gas composition sampling electric control valve. The protective gas pipeline is connected to the protective gas source, and the protective gas is provided to the working chamber through the electric control valve to change the gas composition in the chamber and increase the atmosphere pressure in the chamber; the vacuum pumping pipeline is connected to the vacuum pump, and when the electric control valve is opened and the vacuum pump is working, the chamber is vacuumed to reduce the gas in the chamber and reduce the atmosphere pressure in the chamber; when the lens protective gas continues to enter the working chamber and causes the pressure to be too high, the one-way valve automatically discharges the gas in the chamber to prevent the pressure in the chamber from continuing to rise; the pressure detector and the gas composition detector detect the gas pressure and composition in the chamber respectively, and the computer sends instructions to the control system to control the switch of the electric control valve, the start and stop of the vacuum pump, and the supply of protective gas based on the real-time detection data, so as to adjust the atmosphere pressure and composition in the working chamber.

5. The atmosphere-controlled top-mounted online powder-feeding powder bed additive manufacturing equipment according to claim 1 is also characterized by: For additive manufacturing processes that require inert gas protection, before additive manufacturing, close the protective gas pipeline electronic control valve, open the vacuum pipeline electronic control valve, start the vacuum pump, and use the vacuum pump to evacuate the working chamber until the pressure detector shows that the working chamber has reached a suitable vacuum degree. Then close the vacuum pump and the vacuum pipeline electronic control valve, connect the protective gas source, open the protective gas pipeline electronic control valve, and fill the inert gas until the gas pressure in the working chamber forms a slight positive pressure regulated by a one-way valve relative to the air outside the chamber, so as to prevent the air outside the chamber from infiltrating into the chamber and increasing the pressure. Oxygen content, close the electric control valve of the protective gas pipeline to maintain the lens protective gas delivery; if the atmosphere detector detects and shows that the oxygen content in the working chamber is too high, first suspend the XY scanning of the additive manufacturing, the lifting of the forming cylinder piston, the powder supply and powder spreading, etc., close the electric control valves of all air inlet pipes, open the electric control valve of the vacuum pipeline, start the vacuum pump, and after a certain amount of gas in the cavity is pumped away, stop the vacuum pump, close the electric control valve of the vacuum pipeline, open the air inlet pipe, and fill it with inert gas. Pump and fill in this way until the oxygen content in the working chamber meets the process requirements.

6. The atmosphere-controlled top-mounted online powder-feeding powder bed additive manufacturing equipment according to claim 1 is also characterized by: The atmosphere temperature measurement and control system is composed of a temperature detector, a cooling water circuit and its electric control valve, a water cooling jacket and a water cooling machine. The temperature detector detects the atmosphere temperature in the working chamber, the water cooling machine provides cooling water to the water cooling jacket through the cooling water circuit and the electric control valve, and the gas circulation pipeline passes through the water cooling jacket. During the additive manufacturing process, the computer decides whether the control system opens the electric control valve and allows cooling water to enter the water-cooling jacket to cool the circulating gas in the gas circulation pipeline based on whether the detected temperature data exceeds the set value. The cooled circulating gas returns to the working chamber to cool the gas, powder and the inner wall of the working chamber, thereby reducing the atmosphere temperature in the chamber to an appropriate temperature range.

7. The atmosphere-controlled top-mounted online powder-feeding powder bed additive manufacturing equipment according to claim 1 is also characterized by: The upper-mounted online powder recovery and supply system consists of a powder screening and supplying machine, a powder conveying pipeline, an upper-mounted quantitative powder feeding mechanism, an overflow trough, an overflow collecting hopper, a manual ball valve, a powder storage tank, and an electric-controlled valve for the powder conveying pipeline. The powder conveying pipeline and the electric-controlled valve between the powder screening and supplying machine and the upper-mounted quantitative powder feeding mechanism constitute a powder supply channel, which starts from the front and rear overflow troughs on the powder spreading platform and respectively passes through the overflow collecting hopper, the manual ball valve, the powder storage tank, and the electric-controlled valve to converge into a powder conveying pipeline, and then the channel to the powder screening and supplying machine is the powder recovery channel.

8. The top-mounted online powder recovery and supply system according to claim 7 is also characterized by: The powder screening and feeding machine can suck powder from the powder recovery channel and blow powder to the powder supply channel. The computer can command the control system to open the electric control valve on the powder supply channel, control the powder screening and feeding machine to convey the stored powder to the upper quantitative powder feeding mechanism through the conveying pipeline by air, and can also open the electric control valve on the powder recovery channel, control the powder screening and feeding machine to convey the overflowed powder to the upper quantitative powder feeding mechanism by air through the conveying pipeline for screening and storage.

9. The top-mounted online powder recovery and supply system according to claim 7 is also characterized by: The upper-mounted quantitative powder feeding mechanism consists of a powder bin, a powder bin supporting shaft, a powder remaining amount monitoring device in the powder bin, a quantitative powder feeding motor drive system, and an impeller shaft quantitative powder feeding body. The mechanism is suspended on a suspension beam of a working box through a flange on the top of the powder bin and the powder bin supporting shaft. A computer calculates the powder demand according to the thickness and area of ​​a powder layer to be scanned, sets the rotation angle of the quantitative powder feeding impeller shaft, and issues a command to a control system to control the quantitative powder feeding motor drive system to drive the quantitative powder feeding impeller shaft to rotate to a set angle. The quantitative powder in the powder bin falls into a powder spreading mechanism located directly below the impeller shaft quantitative powder feeding body, and the powder spreading mechanism spreads a layer of powder on the surface of the powder bed.

10. The top-mounted online powder recovery and supply system according to claim 7, further characterized by: The powder residue monitoring device in the powder bin monitors the powder residue and stacking flatness in the bin online during the additive manufacturing process. The computer promptly sends instructions to the control system based on the requirements of the additive manufacturing of the parts and the real-time monitored powder residue and stacking flatness in the bin, and controls the powder screening and feeding machine and the electric control valve of the powder feeding channel to convey powder to the upward quantitative powder feeding mechanism.

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