A powder feeding device for 3D printers with dynamic monitoring of powder flowability

Abstract

This invention provides a powder feeding device for a 3D printer with dynamic monitoring of powder flowability, relating to the field of selective laser melting (SLM) technology. The powder feeding device includes an SLM printer housing, an infrared temperature measurement module mounted on the top of the SLM printer housing and controlled by a multi-dimensional displacement drive mechanism, a laser printing mechanism adjacent to the infrared temperature measurement module along the laser path and used for selective laser melting, and a powder recovery mechanism built into the front side of the SLM printer housing and adapted to the front end of the laser forming area. This invention solves the problem that in scenarios where fine powder is not fully filled, fine powder particles are easily driven by gravity to settle through the pores of the coarse powder matrix, eventually forming a rich layer at the bottom of the hopper. This layer is then affected by the laser during discharge, causing splashing and damaging the parts during processing. This invention provides a new technical path for the efficient utilization of metal powder in unsaturated filling conditions.

Description

Technical Field

[0001] This invention relates to the field of selective laser melting technology, specifically to a powder feeding device for a 3D printer with dynamic monitoring of powder flowability. Background Technology

[0002] SLM (Selective Laser Melting) technology involves layering metal powder onto a forming platform, then using a high-energy laser beam to selectively melt the powder based on the part's cross-sectional information. After the molten layer solidifies, the platform descends by one layer thickness, repeating the powder layering and melting process until a three-dimensional solid is formed. Its core principle is based on discrete-stacking to achieve near-net-shape forming of materials, making it a novel industrial laser 3D printing technology. The delivery and spreading of metal powder in the SLM process lays a solid foundation for subsequent selective laser melting. Taking a quantitative powder feeder for an SLM 3D printer (authorized announcement number CN105293102B) as an example, it uses a vertical sand box, outer cylinder, and rotor in conjunction. The rotor rotation is linked by a powder scraper, causing the rotor's slots to alternately engage with the powder inlet and outlet, achieving quantitative powder feeding. This primarily solves the problem of difficult quantitative powder feeding in traditional vertical powder boxes, ensuring precise and controllable powder quantity for each layer. This provides crucial support for stable powder layering, uniform melting, and part forming quality in the SLM process.

[0003] In the SLM process, introducing fine particles to fill the gaps between coarse powder particles and reduce porosity is a key method to improve the packing density of metal powder. This is consistent with the core logic of powder particle size distribution optimization. However, the amount of fine particles added needs to be strictly controlled, which presents a significant inherent contradiction: when the proportion of fine particles is too high, due to their large specific surface area, the interfacial forces such as van der Waals forces and electrostatic forces between particles are sharply enhanced, easily forming hard agglomerates. This leads to deterioration of powder flowability during powder spreading, resulting in local voids, thickness fluctuations, and "bridging" phenomena in the powder layer. Furthermore, during the laser melting stage, agglomerated fine particles are prone to spatter due to absorbing too much energy, disrupting the stability of the molten pool. If the amount of fine particles added is insufficient, and the fine particles are easily driven by gravity through the coarse powder particles... The pores of the powder skeleton settle and eventually form an enriched layer at the bottom of the hopper. This layer cannot effectively participate in the powder layer construction, resulting in a decrease in packing efficiency. To alleviate the inherent contradiction of adding fine particles and improve part yield, existing technologies often use numerical models (such as packing simulation based on Andersen equations or response surface methodology optimization) or experimental statistical analysis to solve for the optimal ratio of fine to coarse particles under specific process conditions. However, in practical applications, the powder diameter parameter has certain part-specific characteristics. This requires existing models to be recalibrated and iteratively verified for the powder diameter of each type of part. This not only prolongs the process preparation cycle but also makes it difficult to achieve efficient adaptation across parts, ultimately leading to a significant reduction in the overall efficiency of ratio optimization.

[0004] Based on this, the present invention provides a new technical path for the efficient utilization of metal powder in unsaturated filling scenarios by monitoring powder flowability to determine the accumulation state of fine particles in real time, thereby enabling secondary filling of fine particles into the gaps between coarse powder. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a powder feeding device for 3D printers with dynamic monitoring of powder flowability. This solves the problem that in scenarios where fine powder is not fully filled, fine powder is easily driven by gravity to settle through the pores of the coarse powder skeleton, eventually forming an enriched layer at the bottom of the hopper. This layer is then affected by the laser during discharge, causing splashing and damaging the parts during processing. This invention provides a new technical path for the efficient utilization of metal powder in unsaturated filling conditions.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a powder feeding device for a 3D printer with dynamic monitoring of powder flowability, comprising an SLM printer housing, an infrared temperature measurement module mounted on the top of the SLM printer housing and controlled by a multi-dimensional displacement drive mechanism, a laser printing mechanism adjacent to the infrared temperature measurement module along the laser light path and used for selective laser melting and forming, a powder recovery mechanism built into the front side inside the SLM printer housing and adapted to the front end of the laser forming area, and a powder adding mechanism integrated on the top of the SLM printer housing for quantitatively supplying metal powder to the forming area, further comprising:

[0007] A powder feeding mechanism, comprising a sand box for holding metal powder and for uniformly spreading the powder in the laser forming area.

[0008] A linear conveying guide rail is arranged on the left and right sides of the laser forming area inside the SLM printer housing, and is used to drive the powder feeding mechanism to slide linearly along its preset trajectory direction.

[0009] The top of the sand box has a wide opening structure and gradually narrows from the top to the bottom. The bottom of the sand box forms a cylindrical receiving part adapted to the quantitative output of powder. The moving end of the linear conveying guide rail is provided with a mounting frame for supporting the sand box. The mounting frame is equipped with a top material assembly for driving the sand box to achieve up-and-down reciprocating vibration. The two side walls of the sand box are respectively fixed with ear hooks that cooperate with the top material assembly.

[0010] A rolling feeder is rotatably mounted on the inner wall of the cylindrical receiving part of the sand box. The outer peripheral wall of the rolling feeder is provided with several trough-shaped receiving parts for quantitatively accommodating metal powder. The opening of each trough-shaped receiving part is adapted to the feeding trough of the sand box leading to the cylindrical receiving part and the discharging trough at the bottom of the cylindrical receiving part leading to the outside.

[0011] The inner core of the rolling distributor is rotatably connected to a heat source assembly. The heat source assembly includes an air supply pipe with a built-in heating rod core. A filter screen is installed on the outer wall of the air supply pipe corresponding to the air outlet. A rotating joint is installed on the outer wall of the air supply pipe. The rotating joint is used to achieve a sealed connection with the atmospheric gas supply equipment.

[0012] The air outlet of the air supply pipe is matched with the groove-shaped receiving part of the rolling distributor. A slider is fixed to the outer wall of the air supply pipe. A matching guide groove is opened in the slider. A limiting block that slides with the guide groove is fixed to the mounting bracket near the slider. The limiting block is embedded in and limits the sliding within the guide groove of the slider.

[0013] The powder feeding mechanism also includes a powder detection component for monitoring the flowability of powder inside the sand box.

[0014] Preferably, a dustproof box is installed on the left side wall of the sand box. The dustproof box is a sealed box consisting of a box body and an outer end cover. A drive motor is installed on the top of the dustproof box. A drive bevel gear is connected to the movable end of the drive motor. A transmission bevel gear that meshes with the drive bevel gear is installed on the left end of the rolling feeder.

[0015] Preferably, both mounting brackets are equipped with dustproof guide rails, and drive cylinders are installed on the outer walls of the dustproof guide rails. Limiting slide rails are installed on the two side walls of the dustproof guide rails. A sliding support rod is slidably connected to the top of the mounting bracket. A roller is installed on the top of the sliding support rod. The movable end of the drive cylinder is connected to the sliding support rod. The bottom of the limiting slide rail has a groove structure that slopes from back to front. The top roller of the sliding support rod is rotatably connected to the groove at the bottom of the limiting slide rail.

[0016] Preferably, a drive gear plate is slidably connected inside the dustproof guide rail, and the drive gear plate can slide up and down inside the dustproof guide rail. Both ends of the sliding support rod are connected to transmission rods, and the other ends of the two transmission rods are rotatably connected to the outer wall of the drive gear plate. The top material assembly is rotatably connected inside the dustproof guide rail, and a gear structure that meshes with the drive gear plate is installed on the outer wall of the top material assembly.

[0017] Preferably, a water storage tank is attached to the rear side wall of the sand box, and a flat roller is connected to the inner wall of the water storage tank by a spring. The top of the flat roller and the inner wall of the water storage tank form a sealed sliding connection pair. Suspended guide tubes are attached to the two side walls of the water storage tank. A spring piston is connected to the suspended guide tube by a spring, and the top of the suspended guide tube is connected to the inside of the water storage tank by a hose.

[0018] Preferably, the movable end of the top material assembly is positioned opposite the bottom of the spring piston to drive the spring piston to slide along the inner wall of the suspended guide tube.

[0019] Preferably, the top of the sand box is slidably connected to a spring cover via a slide rail, and the spring cover is connected to the slide rail at the top of the sand box via a spring. The bottom of the powder adding mechanism is flush with the spring cover.

[0020] Preferably, the powder detection component includes a flowability sensor installed on the inner wall of the sand box. The monitoring end of the flowability sensor extends into the metal powder accumulation area inside the sand box to collect the powder's bulk density parameters in real time and transmit the monitoring data to the main control system of the 3D printer in real time.

[0021] The present invention has the following technical features and beneficial effects:

[0022] 1. It can monitor powder flowability in real time and automatically complete the secondary filling of fine particles into the gaps between coarse powder, effectively ensuring the molding quality of unsaturated filled powder, while shortening the process preparation cycle, improving the adaptation efficiency across parts, and providing a new path for the efficient utilization of metal powder in the unsaturated filled state.

[0023] 2. By leveraging the synergistic effect of the rolling feeder and the ambient gas, the powder achieves a higher initial velocity, promoting the embedding of fine particles into the deep particle gaps and preventing fine particles from accumulating on the surface of the powder layer, thereby preventing the splattering of fine powder particles during subsequent laser processing.

[0024] 3. By driving the flat roller to move up and down through the top material assembly, the powder laid in the laser processing section can be evenly distributed, improving the uniformity of powder laying and laying the foundation for subsequent processing quality. At the same time, combined with the infrared temperature measurement module to dynamically adjust the ambient gas temperature and the activity frequency of the top material assembly, the preheating temperature of the metal powder can be increased, the density of powder particles can be increased, the heat conduction efficiency can be improved, the temperature gradient can be reduced, the accumulation of thermal stress can be reduced, and the generation of cracks on the workpiece surface can be effectively avoided. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the present invention;

[0026] Figure 2 This is a schematic diagram of the linear conveying guide rail and powder feeding mechanism in this invention;

[0027] Figure 3 This is a schematic diagram of the linear conveying guide rail and the powder feeding mechanism after the spring cover is separated from the sand box in this invention.

[0028] Figure 4 This is an isometric side sectional view of the powder feeding mechanism in this invention;

[0029] Figure 5 This is a schematic diagram of the structure of the powder feeding mechanism after the dustproof guide rail is hidden on the right side in this invention;

[0030] Figure 6 for Figure 5 Enlarged view of point A in the middle;

[0031] Figure 7 This is a schematic diagram of the structure of the powder feeding mechanism in this invention, showing the hidden dustproof guide rail and the limiting slide rail on the left side after half-section.

[0032] Figure 8 for Figure 7 Enlarged view of point B in the middle;

[0033] Figure 9 This is a schematic diagram of the structure of the powder feeding mechanism in this invention after concealing the dustproof guide rail, the suspended guide tube and the water tank.

[0034] Figure 10 This is a schematic diagram of the internal structure of the dustproof box of the powder feeding mechanism in this invention after separation.

[0035] Figure 11 This is a schematic diagram of the cooperation structure between the drive motor of the powder feeding mechanism and the rolling feeder in this invention;

[0036] Figure 12 This is a schematic diagram of the cooperation structure of the slider, limiting block and heat source assembly of the powder feeding mechanism in this invention.

[0037] The components include: 1. SLM printer housing; 2. Infrared temperature measurement module; 3. Powder recovery mechanism; 4. Laser printing mechanism; 5. Linear conveyor rail; 6. Powder feeding mechanism; 7. Powder adding mechanism.

[0038] 61. Sand box; 62. Dustproof guide rail; 63. Spring cover; 64. Mounting bracket; 65. Water tank; 66. Flat roller; 67. Powder detection assembly; 68. Top material assembly; 69. Drive toothed plate; 610. Transmission connecting rod; 611. Limit slide rail; 612. Drive cylinder; 613. Sliding support rod; 614. Rolling distributor; 615. Heat source assembly; 616. Suspended guide tube; 617. Ear hook; 618. Spring piston; 619. Dustproof box; 620. Drive motor; 621. Transmission bevel gear; 622. Drive bevel gear; 623. Slider; 624. Limit block;

[0039] 6151. Rotary joint; 6152. Filter screen; 6153. Air supply pipe. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Example 1, as Figures 1-2 As shown, this embodiment of the invention provides a powder feeding device for a 3D printer with dynamic monitoring of powder flowability. It includes an SLM printer housing 1, an infrared temperature measurement module 2 mounted on the top of the SLM printer housing 1 and controlled by a multi-dimensional displacement drive mechanism, a laser printing mechanism 4 adjacent to the infrared temperature measurement module 2 along the laser path and used for selective laser melting and forming, a powder recovery mechanism 3 built into the front side of the SLM printer housing 1 and adapted to the front end of the laser forming area, and a powder adding mechanism 7 integrated on the top of the SLM printer housing 1 for quantitatively supplying metal powder to the forming area. It also includes a powder feeding mechanism 6, which includes a sand box 61 for containing metal powder and uniformly spreading the powder in the laser forming area, and a linear conveying guide rail 5. The linear conveying guide rail 5 is arranged on the left and right sides of the laser forming area inside the SLM printer housing 1 to drive the powder feeding mechanism 6 to slide linearly along its preset trajectory direction.

[0042] like Figure 11 As shown, the powder feeding mechanism 6 also includes a powder detection component 67 for monitoring the flowability of powder inside the sand box 61. The powder detection component 67 includes a flowability sensor installed on the inner wall of the sand box 61. The monitoring end of the flowability sensor extends into the metal powder accumulation area inside the sand box 61 to collect the powder's bulk density parameter in real time and transmit the monitoring data to the main control system of the 3D printer in real time. The powder detection component 67, which is a flowability sensor, is installed at the bottom of the sand box 61 to monitor the powder stored in the sand box 61. The monitoring end of the flowability sensor extends into the metal powder accumulation area inside the sand box 61 to collect the powder's bulk density parameter in real time and transmit the monitoring data to the main control system of the printer in real time. When the bulk density of fine powder particles at the bottom of the sand box 61 is too high, the monitoring end feeds back the collected data to the main control system.

[0043] It should be noted that the powder detection component 67 used in this device is a powder flowability type, with the optional model being FlowJam-T. It mainly monitors the content of fine powder particles inside the sand box 61 by detecting the amount of deformation of the hose.

[0044] Example 2, as Figure 5-7As shown, this embodiment provides another technical solution based on embodiment one. The top of the sand box 61 has a wide opening structure and gradually narrows from the top to the bottom. Its bottom end forms a cylindrical receiving part adapted to the quantitative output of powder. The moving end of the linear conveying guide rail 5 is provided with a mounting frame 64 for supporting the sand box 61. The mounting frame 64 is equipped with a top material assembly 68 for driving the sand box 61 to achieve up and down reciprocating vibration. The two side walls of the sand box 61 are correspondingly fixed with ear hooks 617 that cooperate with the top material assembly 68.

[0045] like Figure 4 and Figures 11-12 As shown, a rolling feeder 614 is rotatably mounted on the inner wall of the cylindrical receiving part of the sand box 61. The outer peripheral wall of the rolling feeder 614 has several groove-shaped receiving parts for quantitatively containing metal powder. The opening of each groove-shaped receiving part is adapted to the feeding trough of the sand box 61 leading to the cylindrical receiving part and the discharge trough at the bottom of the cylindrical receiving part leading to the outside. The inner core of the rolling feeder 614 is rotatably connected to a heat source assembly 615. The heat source assembly 615 includes an air supply pipe 6153 with a built-in heating rod core. A filter screen 6152 is installed on the outer wall of the air supply pipe 6153 corresponding to the air outlet. A rotating joint 6151 is installed on its outer wall. The rotating joint 6151 is used to achieve sealed communication with the atmospheric gas supply equipment.

[0046] like Figure 4 and Figure 12 As shown, the air outlet of the air supply pipe 6153 corresponds to and is adapted to the groove-shaped receiving part of the rolling distributor 614. A slider 623 is fixedly connected to the outer wall of the air supply pipe 6153. A matching guide groove is opened in the slider 623. A limiting block 624 that slides with the guide groove is fixedly provided on the mounting bracket 64 near the slider 623. The limiting block 624 is embedded in and limits the sliding within the guide groove of the slider 623.

[0047] Example 3, as Figures 10-11As shown, this embodiment provides another technical solution based on Embodiment 1 and Embodiment 2. A dustproof box 619 is installed on the left side wall of the sand box 61. The dustproof box 619 consists of a box body and an external end cover to form a sealed box. A drive motor 620 is installed on the top of the dustproof box 619. A drive bevel gear 622 is connected to the movable end of the drive motor 620. A transmission bevel gear 621 that meshes with the drive bevel gear 622 is installed on the left end of the rolling feeder 614. Dustproof guide rails 6 are installed on both mounting brackets 64. 2. A drive cylinder 612 is installed on the outer wall of the dustproof guide rail 62. Limiting slide rails 611 are installed on both side walls of the dustproof guide rail 62. A sliding support rod 613 is slidably connected to the top of the mounting bracket 64. A roller is installed on the top of the sliding support rod 613. The movable end of the drive cylinder 612 is connected to the sliding support rod 613. A groove structure with an inclination from back to front is opened at the bottom of the limiting slide rail 611. The top roller of the sliding support rod 613 is slidably connected to the groove at the bottom of the limiting slide rail 611.

[0048] like Figures 5-6 As shown, a drive toothed plate 69 is slidably connected inside the dustproof guide rail 62. The drive toothed plate 69 can slide up and down inside the dustproof guide rail 62. The two ends of the sliding support rod 613 are connected to the transmission connecting rods 610. The other ends of the two transmission connecting rods 610 are rotatably connected to the outer wall of the drive toothed plate 69. The top material assembly 68 is rotatably connected inside the dustproof guide rail 62. A gear structure that meshes with the drive toothed plate 69 is installed on the outer wall of the top material assembly 68. A water storage tank 65 is hung on the rear side wall of the sand box 61. A flat material roller 66 is connected to the inner wall of the water storage tank 65 by a spring. The top of the flat material roller 66 and the inner wall of the water storage tank 65 form a sealed sliding connection pair. Suspended guide tubes 616 are hung on the two side walls of the water storage tank 65. A spring piston 618 is connected to the suspended guide tube 616 by a spring. The top of the suspended guide tube 616 is connected to the inside of the water storage tank 65 by a hose.

[0049] like Figure 3 , Figure 5 , Figure 7 and Figure 9 As shown, the movable end of the top material assembly 68 is directly opposite the bottom of the spring piston 618 to drive the spring piston 618 to slide along the inner wall of the suspended guide tube 616. The top of the sand box 61 is slidably connected to the spring cover 63 via a slide rail. The spring cover 63 is connected to the top slide rail of the sand box 61 via a spring. The bottom of the powder adding mechanism 7 is flush with the spring cover 63.

[0050] Working Principle: This device uses a powder detection component 67 located at the bottom of the sand box 61 to monitor the powder stored inside the sand box 61. The powder detection component 67 is a flowability sensor. The monitoring end of the flowability sensor extends into the metal powder accumulation area inside the sand box 61 to collect the powder's bulk density parameter in real time and transmit the monitoring data to the printer's main control system in real time. When the bulk density of fine powder particles at the bottom of the sand box 61 is too high, the monitoring end feeds back the collected data to the main control system. After receiving the feedback data from the monitoring end, the main control system controls the drive cylinder 612 through the control module to drive the sliding support rod 613 to slide backward, so that the sliding support rod 613 moves to the limit slide rail 611. On the rear side, due to the groove shape of the limiting slide rail 611, the sand box 61 slides downward as a whole. At this time, under the guidance of the limiting block 624, the slider 623 pulls the air supply pipe 6153 to rotate as a whole. At this time, the ventilation slot of the air supply pipe 6153 is directly opposite the top groove of the rolling feeder 614, thus making the ventilation slot of the air supply pipe 6153 connected to the inner cavity of the sand box 61. While the drive cylinder 612 drives the sliding support rod 613 to slide, the drive tooth plate 69 is driven to slide downward under the drive of the transmission connecting rod 610. At this time, under the drive of the drive tooth plate 69, the top material assembly 68 flips upward as a whole. As the sand box 61 slides downward as a whole, the movable end of the top material assembly 68 presses against the bottom of the ear hooks 617 on both sides of the sand box 61.

[0051] Subsequently, the top-feeding assembly 68 is activated, which lifts the sand box 61 upwards. During this upward movement, the air supply pipe 6153 deflects under the pull of the limit block 624. The ventilation slot of the air supply pipe 6153 then turns towards the sealed port of the rolling distributor 614. At this point, the ambient gas enters the air supply pipe 6153 and, unable to escape, accumulates within it, causing the gas pressure to rise. Then, the movable end of the top-feeding assembly 68 descends rapidly. The sand box 61, now unsupported by the top-feeding assembly 68, moves downwards. The metal powder stored within the sand box 61 then moves within it, increasing the gaps between the powder particles. When the sand box 61 is reset, the vent of the air supply pipe 6153 is connected to the inner cavity of the sand box 61 again. At this time, high-pressure gas is blown into the sand box 61, causing the fine powder particles that were originally piled up at the bottom of the sand box 61 to be blown back into the gaps of the coarse powder particles. In the case of unsaturated powder filling, the fine particle accumulation state can be judged in real time by monitoring the powder flowability, and then the secondary filling of fine particles into the gaps of coarse powder can be automatically completed. While ensuring the molding quality of unsaturated filled powder, the process preparation cycle is effectively shortened and the cross-part adaptation efficiency is improved. This provides a new technical path for the efficient utilization of metal powder in the unsaturated filling state and solves the problems of low efficiency and poor adaptability of the existing ratio optimization method.

[0052] While the powder feeding mechanism 6 is conveying powder and laying it in the laser processing section, the drive motor 620 drives the drive bevel gear 622 to rotate, which in turn drives the transmission bevel gear 621 and the rolling distributor 614 to rotate together. This causes the powder in the sand box 61 to periodically fall into the trough of the rolling distributor 614. At the same time, the external air supply equipment continuously injects gas into the air supply pipe 6153. When the rolling distributor 614 rotates to connect with the ventilation slot of the air supply pipe 6153, the air enters the trough of the rolling distributor 614, thereby preheating the gas inside the trough. During the rotation of the rolling feeder 614, a seal is formed between the trough of the rolling feeder 614 and the sand box 61. At this time, the gas cannot escape after entering, which increases the air pressure inside the rolling feeder 614. When the trough of the rolling feeder 614 rotates to connect with the bottom discharge trough of the sand box 61, the powder gains a higher initial velocity under the drive of air pressure, which counteracts the obstruction of air resistance and overcomes the obstruction of the surface-laid particles. This makes it easier for fine particles to embed into the gaps between the deep particles, thus preventing fine powder particles from accumulating on the surface of the laid powder and avoiding the occurrence of fine powder splashing during subsequent laser processing.

[0053] While the powder feeding mechanism 6 conveys powder and lays it in the laser processing section, the movable end of the top material assembly 68 continuously extends, thereby actuating the spring piston 618 inside the suspended guide tube 616. The liquid originally stored in the suspended guide tube 616, under the pressure of the spring piston 618, flows back and forth through the hose between the suspended guide tube 616 and the water tank 65. At this time, the flat roller 66 moves up and down, pressing the powder laid in the laser processing section to ensure uniform distribution. Simultaneously, the infrared temperature measurement module 2 monitors the surface temperature of the laser processing section. When the powder feeding mechanism 6 moves near the workpiece, the infrared temperature measurement module 2 detects a significant increase in its surface temperature. The main controller at the printing end controls the heating rod in the air supply pipe 6153 to turn on, thereby increasing the temperature of the ambient gas entering the air supply pipe 6153, which in turn increases the preheating temperature of the metal powder and reduces the formation of gaps on the surface of the molded workpiece due to excessive temperature gradient difference. At the same time, the main control system controls the movement frequency of the moving end of the top material assembly 68 to increase the vibration frequency of the flat roller 66, thereby increasing the density of the powder particles in the workpiece attachment, increasing the contact area between powder particles, significantly improving the heat conduction efficiency, and allowing heat to be transferred more evenly in the powder layer. This avoids "sudden change in thermal resistance" caused by local porosity, thereby reducing the temperature gradient and comprehensively reducing the accumulation of thermal stress caused by excessive temperature gradient, thus preventing the generation of cracks on the surface of the workpiece.

[0054] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A powder feeding device for a 3D printer with dynamic monitoring of powder flowability, comprising an SLM printer housing (1), an infrared temperature measurement module (2) mounted on the top of the SLM printer housing (1) and controlled by a multi-dimensional displacement drive mechanism, a laser printing mechanism (4) configured adjacent to the infrared temperature measurement module (2) along the laser path and used for selective laser melting and forming, a powder recovery mechanism (3) built into the front side inside the SLM printer housing (1) and adapted to the front end of the laser forming area, and a powder adding mechanism (7) integrated on the top of the SLM printer housing (1) for quantitatively supplying metal powder to the forming area, characterized in that, Also includes: The powder feeding mechanism (6) includes a sand box (61) for holding metal powder and for uniformly spreading the powder in the laser forming area. Linear conveying guide (5), the linear conveying guide (5) is arranged on the left and right sides of the laser forming area inside the SLM printer box (1) to drive the powder feeding mechanism (6) to slide linearly along its preset trajectory direction. The top of the sand box (61) is a wide-mouth structure and gradually narrows from the top to the bottom. The bottom of the sand box forms a cylindrical receiving part that is adapted to the quantitative output of powder. The moving end of the linear conveying guide rail (5) is provided with a mounting frame (64) for supporting the sand box (61). The mounting frame (64) is equipped with a top material assembly (68) for driving the sand box (61) to achieve up-and-down reciprocating vibration. The two side walls of the sand box (61) are respectively fixed with ear hooks (617) that cooperate with the top material assembly (68). A rolling feeder (614) is rotatably mounted on the inner wall of the cylindrical receiving part of the sand box (61). The outer peripheral wall of the rolling feeder (614) is provided with several trough-shaped receiving parts for quantitatively containing metal powder. The opening of each trough-shaped receiving part is adapted to the feeding trough of the sand box (61) leading to the cylindrical receiving part and the discharge trough of the bottom of the cylindrical receiving part leading to the outside. The inner core of the rolling feeder (614) is rotatably connected to a heat source assembly (615). The heat source assembly (615) includes an air supply pipe (6153) with a built-in heating rod core. A filter screen (6152) is installed on the outer wall of the air supply pipe (6153) at the air outlet. A rotating joint (6151) is fitted on the outer wall of the air supply pipe. The rotating joint (6151) is used to achieve a sealed connection with the atmospheric gas supply equipment. The air outlet of the air supply pipe (6153) is matched with the groove-shaped receiving part of the rolling feeder (614). A slider (623) is fixedly connected to the outer wall of the air supply pipe (6153). A matching guide groove is opened in the slider (623). A limiting block (624) that slides with the guide groove is fixedly provided on the mounting bracket (64) near the slider (623). The limiting block (624) is embedded in and limits the sliding within the guide groove of the slider (623). The powder feeding mechanism (6) also includes a powder detection component (67) for monitoring the flowability of powder inside the sand box (61).

2. The powder feeding device for a 3D printer with dynamic monitoring of powder flowability according to claim 1, characterized in that, A dustproof box (619) is installed on the left side wall of the sand box (61). The dustproof box (619) is a sealed box consisting of a box body and an outer end cover. A drive motor (620) is installed on the top of the dustproof box (619). A drive bevel gear (622) is connected to the movable end of the drive motor (620). A transmission bevel gear (621) that meshes with the drive bevel gear (622) is installed on the left end of the rolling feeder (614).

3. The powder feeding device for a 3D printer with dynamic monitoring of powder flowability according to claim 1, characterized in that, Dustproof guide rails (62) are installed on both mounting brackets (64). A drive cylinder (612) is installed on the outer wall of the dustproof guide rail (62). Limiting slide rails (611) are installed on both side walls of the dustproof guide rail (62). A sliding support rod (613) is slidably connected to the top of the mounting bracket (64). A roller is installed on the top of the sliding support rod (613). The movable end of the drive cylinder (612) is connected to the sliding support rod (613). The bottom of the limiting slide rail (611) has a groove structure that is inclined from the drive cylinder (612) to the ear hook (617). The top roller of the sliding support rod (613) is slidably connected to the groove at the bottom of the limiting slide rail (611).

4. A powder feeding device for a 3D printer with dynamic monitoring of powder flowability according to claim 3, characterized in that, The dustproof guide rail (62) is internally slidably connected to a drive toothed plate (69), which can slide up and down inside the dustproof guide rail (62). The two ends of the sliding support rod (613) are connected to transmission connecting rods (610), and the other ends of the two transmission connecting rods (610) are rotatably connected to the outer wall of the drive toothed plate (69). The top material assembly (68) is rotatably connected inside the dustproof guide rail (62), and a gear structure that meshes with the drive toothed plate (69) is installed on the outer wall of the top material assembly (68).

5. A powder feeding device for a 3D printer with dynamic monitoring of powder flowability according to claim 1, characterized in that, A water storage tank (65) is attached to the rear side wall of the sand box (61). A flat roller (66) is connected to the inner wall of the water storage tank (65) by a spring. The top of the flat roller (66) and the inner wall of the water storage tank (65) form a sealed sliding connection pair. A suspended guide tube (616) is attached to both sides of the water storage tank (65). A spring piston (618) is connected to the suspended guide tube (616) by a spring. The top of the suspended guide tube (616) is connected to the inside of the water storage tank (65) by a hose.

6. A powder feeding device for a 3D printer with dynamic monitoring of powder flowability according to claim 1, characterized in that, The movable end of the top material assembly (68) is directly opposite the bottom of the spring piston (618) and is used to drive the spring piston (618) to slide along the inner wall of the suspended guide tube (616).

7. A powder feeding device for a 3D printer with dynamic monitoring of powder flowability according to claim 1, characterized in that: The top of the sand box (61) is slidably connected to a spring cover (63) via a slide rail. The spring cover (63) is connected to the slide rail at the top of the sand box (61) via a spring. The bottom of the powder adding mechanism (7) is flush with the spring cover (63).

8. A powder feeding device for a 3D printer with dynamic monitoring of powder flowability according to claim 1, characterized in that, The powder detection component (67) includes a flowability sensor installed on the inner wall of the sand box (61). The monitoring end of the flowability sensor extends into the metal powder accumulation area inside the sand box (61) to collect the powder's bulk density parameters in real time and transmit the monitoring data to the main control system of the 3D printer in real time.

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