Binder jetting 3D printing device and printing method for low-fluidity powder
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-09-09
- Publication Date
- 2026-08-13
Smart Images
Figure CN2025120034_13082026_PF_FP_ABST
Abstract
Description
A binder jetting 3D printing device and printing method for low-flowability powder binder Technical Field
[0001] This invention relates to the field of 3D printing technology, and in particular to a binder jetting 3D printing device and printing method for low-flow powder. Background Technology
[0002] Binder jetting (BJ, also commonly known as 3DP) is an additive manufacturing technology based on inkjet technology and a powder bed 3D printing technology. It constructs three-dimensional solid products by selectively jetting binder onto a powder bed and bonding powder particles layer by layer. Using fine powder with poor flowability as the printing powder reduces surface roughness, improves dimensional accuracy and surface quality, and provides better support in the powder bed, preventing damage from shear forces introduced during powder spreading. From a post-processing perspective, it enables the production of products with uniform structure and fine grains, improving their mechanical properties and lifespan. Furthermore, it allows for higher sintering activity during sintering, achieving densification at lower temperatures and reducing sintering energy consumption. However, fine powders with poor flowability have small particle sizes and large specific surface areas. During the conveying process, they are easily attracted to the surfaces of conveying pipes, screws, valves, and filters due to van der Waals forces and electrostatic forces, resulting in uneven and discontinuous powder supply, or even blockage of the conveying device. Secondly, fine powders also adhere to the surface of the spreading roller, changing the effective cross-sectional area and surface roughness of the spreading roller, causing deviations between the actual spreading thickness and the set value. Moreover, fine powders are prone to forming powder agglomerates of varying sizes during the spreading process. Under the pushing of the spreading roller, they cannot be effectively dispersed, resulting in significant deviations in the uniformity of powder density in different areas. Summary of the Invention
[0003] The technical problem to be solved by the present invention is to provide a binder jetting 3D printing device and printing method for low flowability powder, which can improve the printing accuracy of low flowability powder and the uniformity of powder density throughout the entire area, thereby improving the consistency of printed products.
[0004] To address the aforementioned problems, this invention discloses a binder jetting 3D printing method for low-flowability powder, comprising the following steps:
[0005] (1) Control the movement of the powder forming module to reach the initial position; wherein, the powder forming module includes a powder dropping module and a powder spreading module, and the powder dropping module and the powder spreading module move synchronously;
[0006] (2) A preset amount of powder is added to the powder dispensing module through the powder replenishment module, wherein the powder dispensing module includes a powder replenishment receiving plate and a vibrating plate;
[0007] (3) Move the powder forming module to the powder spreading start position, and control the powder receiving plate to make the powder fall onto the vibrating plate;
[0008] (4) By controlling the vibration of the vibrating plate, the powder is transferred to a preset area in front of the powder spreading module, and then the powder spreading module is used to spread and compact the powder in sequence.
[0009] (5) Move the powder forming module to the initial position to complete the single-layer powder spreading;
[0010] (6) Repeat steps (1) to (5) until the base powder layer is laid;
[0011] (7) Repeat steps (1) to (5) on the base powder layer to complete the laying of the slice layer. Control the inkjet module to follow the movement of the powder forming module, spray the binder and solidify the powder in the preset area of each slice layer until the printing of the model is completed and the 3D printed product is obtained.
[0012] As an improvement to the above technical solution, the powder forming module further includes a support, the powder dropping module includes a powder receiving plate and a vibrating plate, and the powder spreading module includes a powder spreading roller and a compacting roller; the powder receiving plate, the vibrating plate, the powder spreading roller and the compacting roller are all fixed on the support, the vibrating plate is located in front of the powder spreading roller, and the compacting roller is located behind the powder spreading roller; there is a preset distance between the vibrating plate and the powder spreading roller to form a preset area for powder transfer.
[0013] As an improvement to the above technical solution, the powder spreading roller is used to sweep up the powder scattered by the powder falling module to obtain a powder spreading layer, wherein the ratio of the density of the powder spreading layer to the loose density of the powder is (0.8~1.2):1.
[0014] The compaction roller is used to compact the powder layer to obtain a compacted powder layer, and the ratio of the density of the compacted powder layer to the density of the powder is (0.8~1.2):1.
[0015] As an improvement to the above technical solution, the ratio of the thickness of the base powder layer to the thickness of each compacted powder layer is (20-40):1;
[0016] The ratio of the thickness of each compacted powder layer to the D50 of the powder is (2-10):1, and / or the ratio of the thickness of each compacted powder layer to the D90 of the powder is (1.5-10):1.
[0017] As an improvement to the above technical solution, the D50 of the powder is 10μm to 100μm, and / or the D90 of the powder is 10μm to 100μm;
[0018] The angle of repose of the powder is 35° to 60°.
[0019] As an improvement to the above technical solution, the bottom of the vibrating plate is higher than the bottom of the powder spreading roller, and the height difference between the vibrating plate and the powder spreading roller is 0.5mm to 5mm.
[0020] The compaction roller and the powder spreading roller rotate in opposite directions. The surface roughness of the compaction roller is less than that of the powder spreading roller. The bottom of the powder spreading roller is higher than the bottom of the compaction roller. The height difference between the powder spreading roller and the compaction roller is 0.01 mm to 1 mm.
[0021] Both the powder receiving plate and the vibrating plate are rotatable relative to the support; the vibration frequency of the vibrating plate is 0.1Hz to 100Hz.
[0022] During the process of adding powder from the powder replenishing module to the powder falling module, the powder replenishing receiving plate is in a horizontal position; during the powder spreading process, the powder replenishing receiving plate has an angle with the horizontal direction so that the powder on the powder replenishing receiving plate falls onto the vibrating plate.
[0023] As an improvement to the above technical solution, the diameter of the compaction roller is 25mm to 120mm and the surface roughness is Ra 0.25 to Ra 3.2, and the diameter of the powder spreading roller is 25mm to 120mm and the surface roughness is Ra 1.6 to Ra 100.
[0024] As an improvement to the above technical solution, the preset path of the inkjet module is as follows: it moves along the Y direction, sprays adhesive and cures bonding powder in a preset area, and then moves a certain distance along the X direction and moves in the opposite direction along the Y direction, sprays adhesive and cures bonding powder in the preset area, and realizes inkjet printing of each slice layer in segments.
[0025] The inkjet module moves at a speed of 100 mm / s to 400 mm / s in the X direction and at a speed of 100 mm / s to 600 mm / s in the Y direction.
[0026] As an improvement to the above technical solution, during the powder spreading process, the moving speed of the powder forming module in the X direction is 50mm / s to 400mm / s;
[0027] The empty travel speed of the powder forming module from the initial position to the powder spreading start position is 250 mm / s to 500 mm / s;
[0028] The powder replenishing module is equipped with a powder outlet vibrator and a powder replenishing belt. The powder replenishing in the powder replenishing module flows out under the action of the powder outlet vibrator. Through the rotation of the powder replenishing belt and the movement of the powder replenishing module in the Y direction, the preset amount of powder is evenly sprinkled on the powder replenishing receiving plate. The preset amount of powder added by the powder replenishing module to the powder falling module each time is 1 to 2 times the amount of powder required for each powder layer.
[0029] Accordingly, the present invention also discloses a binder jetting 3D printing device for low-flowability powder, for performing the above-mentioned binder jetting 3D printing method for low-flowability powder, including a powder replenishment module, a powder forming module, an inkjet module and a platform module.
[0030] The platform module includes a printing platform, which is equipped with a lifting mechanism. The lifting mechanism is connected to the printing platform and is used to drive the printing platform to move up and down in the Z direction.
[0031] The powder forming module and the inkjet module are positioned above the platform module along the X direction; the powder forming module includes a powder dropping module and a powder spreading module that move synchronously; the powder dropping module includes a powder receiving plate and a vibrating plate for vibrating and scattering powder; the powder spreading module includes a powder spreading roller and a compacting roller for spreading and compacting the powder scattered by the powder dropping module; the inkjet module is used to spray adhesive into a preset area of the slice layer;
[0032] The powder replenishment module is located on one side of the platform module and is higher than the powder dropping module, and is used to replenish the powder dropping module.
[0033] Implementing this invention has the following beneficial effects:
[0034] 1. The binder jetting 3D printing method for low-flowability powder provided by the present invention replenishes powder layer by layer through the powder dispensing module before each layer of powder is laid. This can effectively avoid the cumulative error caused by excessive low-flowability powder adhering and agglomerating on the powder dispensing module and the powder laying module, thereby improving printing accuracy. At the same time, it avoids the dependence on precise control of the amount of replenishing powder, reducing the difficulty of replenishing powder.
[0035] 2. The binder jetting 3D printing method for low-flowability powder provided by this invention, by controlling the amplitude and vibration frequency of the vibrating plate set at the powder outlet of the powder delivery module, forms a secondary disruption to the agglomeration and adhesion of the powder. On the one hand, it can improve the flowability of the low-flowability powder, and on the other hand, it can improve the uniformity of powder delivery. At the same time, the powder in the powder delivery module accumulates between the powder spreading module and the powder delivery module as the powder delivery module moves, which can restrict a large amount of powder that has not yet participated in the powder spreading to the vibrating plate, avoiding the damage to the printing area caused by excessive powder accumulation in front of the powder spreading module.
[0036] 3. The following motion of the powder spreading roller and the compaction roller can continuously and timely compact the powder to obtain a high bulk density and effectively improve the uniformity of powder density throughout the entire width, greatly improving product consistency. At the same time, the independent working mode of the powder spreading roller and the compaction roller can give them different roughness to complete different powder sweeping and pressing functions. Therefore, each roller can be designed with a larger diameter to resist deformation, which is more suitable for the needs of large-format industrial equipment. Attached Figure Description
[0037] Figure 1 is a schematic diagram of the structure of the binder jetting 3D printing equipment for low-flowability powder provided by the present invention;
[0038] Figure 2 is an enlarged view of part A in Figure 1;
[0039] Figure 3 is a top view of the binder jetting 3D printing equipment for low-flow powder provided by the present invention.
[0040] Figure 4 is a schematic diagram of the powder replenishment process for laying the base powder layer in the binder jetting 3D printing equipment for low-flow powder provided by the present invention.
[0041] Figure 5 is a schematic diagram of the powder preparation stage for laying the base powder layer in the binder jetting 3D printing equipment for low-flow powder provided by the present invention.
[0042] Figure 6 is a schematic diagram of the powder laying process of the binder jetting 3D printing equipment for low-flow powder provided by the present invention.
[0043] Figure 7 is a schematic diagram of the bottom powder layer laying completed in the binder jet 3D printing equipment for low-flow powder provided by the present invention.
[0044] Figure 8 is a schematic diagram of the powder drop and inkjet process in the printing stage of the low-flowability powder binder jet 3D printing equipment provided by the present invention.
[0045] Figure 9 is a schematic diagram of the powder replenishment stage in the printing phase of the low-flowability powder binder jet 3D printing equipment provided by the present invention.
[0046] Figure 10 is a schematic diagram of the motion control logic of the binder jetting 3D printing equipment for low-flowability powder provided by the present invention;
[0047] Figure 11 is a schematic diagram of the process of laying the base powder layer in the binder jet 3D printing method for low flowability powder provided by the present invention.
[0048] Figure 12 is a schematic diagram of the inkjet printing process of the binder jet 3D printing method for low-flowability powder provided by the present invention. Detailed Implementation
[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail below.
[0050] The present invention provides a binder jetting 3D printing device for low-flow powder, as shown in Figures 1 to 3, including a platform module 10, an inkjet module 20, a powder forming module, printing powder 50, and a powder replenishment module 60, wherein the powder forming module includes a synchronously moving powder spreading module 30 and a powder dropping module 40.
[0051] Specifically, the platform module 10 includes a base 11 and a printing platform 12. The printing platform 12 is equipped with a lifting mechanism connected to the bottom of the printing platform 12, which drives the printing platform 12 to move up and down along the Z direction. One side of the printing platform is the toner spreading start position, and the other side is the initial position. In one embodiment, the platform module 10 also includes a residual toner collection device, which includes a residual toner collection box 13 and a residual toner recovery suction pipe 14. The residual toner collection box 13 and the residual toner recovery suction pipe 14 are located on the side of the printing platform 12 away from the toner spreading start position, and are used to recycle the remaining residual toner 56.
[0052] The powder forming module and inkjet module 20 are positioned along the X-axis on the powder spreading track 15 above the platform module 10. It can be understood that "front" and "back" are defined according to the movement direction of the modules during powder spreading; the direction of movement from the powder spreading start position to the initial position is considered "front," and the opposite direction is considered "rear." The powder forming module includes a powder spreading module 30 and a powder dropping module 40. The powder spreading module 30 and the powder dropping module 40 move synchronously along the X-axis. The powder dropping module 40 is used to sprinkle powder onto the printing platform 12, and the powder spreading module 30 is used to spread the powder sprinkled by the powder dropping module 40 onto the printing platform 12.
[0053] In one embodiment, the powder forming module includes a support, a powder dropping module 40, and a powder spreading module 30. The powder dropping module 40 includes a powder receiving plate 41 and a vibrating plate 44, and the powder spreading module 30 includes a powder spreading roller 35 and a compaction roller 34. The powder receiving plate 41, the vibrating plate 44, the powder spreading roller 35, and the compaction roller 34 are all fixed on the support. The vibrating plate 44 is located in front of the powder spreading roller 35, and the compaction roller 34 is located behind the powder spreading roller 35. There is a preset gap between the vibrating plate 44 and the powder spreading roller 34, forming a preset area for powder transfer. It is understood that the vibrating plate 44, the powder spreading roller 35, and the compaction roller 34 are arranged sequentially from front to back to achieve synchronous powder dropping, spreading, and compaction.
[0054] Specifically, the support includes a powder-feeding mounting base 46 for fixing the powder-feeding module 40 and a powder-spreading mounting base 31 for fixing the powder-spreading module 30. The powder-feeding mounting base 46 is equipped with a powder-receiving plate 41, an eccentric wheel 42, a connecting rod 43, a vibrating plate 44, and a powder baffle 45. One end of the powder-receiving plate 41 is connected to the powder-feeding mounting base 46. The powder-receiving plate 41 can rotate counterclockwise. When rotated to a horizontal position, it receives the powder 52. When rotated to an angle with the horizontal direction, a powder-feeding channel is created, and the powder 52 falls onto the vibrating plate 44. A vibrating plate 44 is located below the powder receiving plate 41. One end of the vibrating plate 44 is hinged to the powder dropping mounting base 46. The drive mechanism 48 is fixed to the powder dropping mounting base 46. The eccentric wheel 42 is connected to the main shaft 49 of the drive mechanism 48. One end of the connecting rod 43 is sleeved on the eccentric wheel 42, and the other end is hinged to the lower surface of the vibrating plate 44. Under the drive of the eccentric wheel 42, the connecting rod 43 drives the vibrating plate 44 to vibrate back and forth along the vibration direction 47. The amplitude and vibration frequency of the vibrating plate 44 are adjusted by the eccentricity and rotation speed of the eccentric wheel 42. A powder baffle 45 is located on the side of the powder spreading module 30 near the powder dropping module 40.
[0055] The powder spreading mounting base 31 is equipped with a powder spreading roller bracket 33 and a compaction roller bracket 32. The powder spreading roller 35 is mounted on the powder spreading roller bracket 33, and the compaction roller 34 is mounted on the compaction roller bracket 32. The powder spreading roller 35 and the compaction roller 34 are arranged back and forth along the X direction. The rotation direction 36 of the compaction roller is opposite to the rotation direction 37 of the powder spreading roller. The powder spreading roller 35 is used to sweep up the powder sprinkled by the powder falling module 40 to obtain a powder spreading layer 53. The compaction roller 34 is used to compact the powder spreading layer 53 to obtain a compacted powder layer 54. The vibrating plate 44, the powder baffle 45, and the powder spreading roller 35 form a triangular area for carrying the falling powder 52.
[0056] The inkjet module 20 includes an integrated slide rail 21, an inkjet scanning track 22, an inkjet head integration mechanism 23, and an inkjet head 24. The setting direction of the inkjet scanning track 22 is perpendicular to the setting direction of the toner spreading track 15. The inkjet head integration mechanism 23 scans along the inkjet scanning track 22 in the Y direction and sprays adhesive 25 into a preset area for bonding. Then, the inkjet module 20 moves a certain distance along the X direction, and the inkjet head integration mechanism 23 moves in the opposite direction along the inkjet scanning track 22. This combination action is repeated until the entire working plane is completed for inkjet printing.
[0057] The powder replenishment module 60 includes a temporary powder hopper 61, a powder replenishment track 62, a powder outlet vibrator 63, a powder replenishment belt 64, and a belt drive shaft 65. The powder replenishment module 60 is located on the side of the platform module 10 away from the powder spreading start position and moves along the Y direction. The powder replenishment module 60 is higher than the powder dropping module 40 and is used to carry the powder replenishment powder 51 and replenish the powder dropping module 40. The powder outlet vibrator 63 vibrates at high frequency, forcing the low-flowability powder replenishment powder 51 to acquire a certain flowability. Driven by the powder replenishment belt 64, it flows out of the temporary powder hopper 61 of the powder replenishment module 60 along the movement direction 66 of the powder replenishment belt 64, and finally fills a certain amount of uniform powder on the powder replenishment receiving plate 41.
[0058] This invention also provides a binder jetting 3D printing method for low-flowability powder, comprising the following steps:
[0059] S1. Control the movement of the powder forming module to reach the initial position; wherein, the powder forming module includes a powder dropping module and a powder spreading module, and the powder dropping module and the powder spreading module move synchronously.
[0060] Specifically, when the powder forming module reaches its initial position, the powder dropping module is located below the powder replenishing module.
[0061] S2. Add a preset amount of powder to the powder dispensing module through the powder replenishment module. The powder dispensing module includes a powder replenishment receiving plate and a vibrating plate.
[0062] Specifically, the toner replenishment module moves along the Y-axis, and the powder in the module flows out under the action of the vibrator at the powder outlet. Through the rotation of the toner replenishment belt, a preset amount of powder is evenly spread onto the horizontally positioned toner receiving plate. In one embodiment, the preset amount of powder added by the toner replenishment module to the toner dispensing module each time is 1 to 2 times the amount of powder required for each layer. By controlling the amount of powder added each time, excessive powder accumulation in the toner dispensing module is avoided, reducing the layering error and improving printing accuracy.
[0063] Understandably, the amount of powder added can be adjusted by the working frequency and amplitude of the vibrator, or by the rotation speed and friction of the powder-adding belt.
[0064] S3. Move the powder forming module to the powder spreading start position, and control the powder receiving plate to make the powder fall onto the vibrating plate.
[0065] Specifically, after the powder forming module returns to the powder spreading starting position, the powder receiving plate flips over and sprinkles the powder onto the vibrating plate. At the same time, the printing platform moves downwards along the Z direction for a certain distance, leaving space for a layer of powder to spread. The moving speed of the printing platform in the Z direction is 5mm / s to 30mm / s.
[0066] S4. By controlling the vibration of the vibrating plate, the powder is transferred to the preset area in front of the powder spreading module, and then the powder spreading module is used to spread and compact it in sequence.
[0067] As the powder forming module moves along the X-axis, the vibrating plate begins to vibrate, improving the flowability of the low-flowability powder and transferring it to a preset area in front of the powder spreading module. With the vibration of the vibrating plate, the low-flowability powder, which had agglomerated under gravity, regains better flowability. At this point, the powder's flowability is insufficient to allow it to flow completely out; instead, it gradually slides down with the movement of the powder spreading module and the vibration of the vibrating plate. To avoid powder shortages or accumulation during the powder spreading process, the amplitude and / or frequency of the vibrating plate need to be adjusted appropriately. It is worth noting that although the vibrating plate provides powder flowability exceeding the minimum requirements, the powder will only flow to a limited area due to the spatial constraints of the vibrating plate and the powder bed. This feature prevents the formation of excessively large powder piles in the forward direction of the powder spreading roller due to changes in powder flowability, thus largely avoiding powder pushing problems caused by excessively large powder piles.
[0068] In a preferred embodiment, the amplitude and frequency of the vibrating plate are adjusted so that the powder in the powder-feeding module accumulates between the powder-spreading module and the powder-dropping module, controlling the accumulation of powder in front of the powder-spreading module and avoiding horizontal powder pushing and vertical crushing of the printed area. The amplitude and frequency of the vibrating plate are adjusted by the eccentricity and rotation speed of the eccentric wheel. To avoid powder shortages or accumulation during powder spreading, the vibration frequency of the vibrating plate is 0.1Hz to 100Hz, exemplarily 1Hz, 5Hz, 10Hz, 30Hz, or 60Hz, but not limited to these. More preferably, the vibration frequency is 5Hz to 20Hz. The eccentricity of the eccentric wheel is 0.1mm to 5mm, exemplarily 0.4mm, 0.8mm, 1mm, 2mm, or 4mm, but not limited to these. More preferably, the eccentricity is 0.4mm to 1mm, and the specific setting is related to the powder flowability and the size of the powder outlet of the vibrating plate.
[0069] While the powder-feeding module completes the powder feeding, the powder-spreading module flattens and compacts the powder. In one embodiment, the powder-spreading speed of the powder forming module along the X direction is 50 mm / s to 400 mm / s, and the idle stroke speed of the powder forming module after replenishing powder is 250 mm / s to 500 mm / s. Correspondingly, the rotation speeds of the compaction roller and the powder-spreading roller, as well as the vibration frequency of the vibrating plate, need to be adjusted proportionally.
[0070] In the powder spreading module, the powder spreading roller and the compaction roller are arranged back and forth along the X direction. The rotation direction of the compaction roller is opposite to that of the powder spreading roller. The powder spreading roller and the compaction roller can be designed separately and driven independently, and their rotation speed and direction can be adjusted independently. It is understood that the powder spreading roller is used to level the powder scattered from the powder falling module to obtain a powder spreading layer, and the compaction roller is used to compact the powder spreading layer to obtain a compacted powder layer. Therefore, the compaction roller is closer to the powder layer than the powder spreading roller. In one embodiment, the bottom of the powder spreading roller is higher than the bottom of the compaction roller, with a height difference of 0.01mm to 1mm, exemplarily 0.05mm, 0.1mm, 0.4mm, 0.6mm, or 0.8mm, but not limited to these, depending on the compactability characteristics of the powder.
[0071] In a preferred embodiment, the compaction roller has a diameter of 25mm to 120mm and a surface roughness of Ra 0.05 to Ra 3.2, while the powder spreading roller has a diameter of 25mm to 120mm and a surface roughness of Ra 1.6 to Ra 100. The powder spreading roller has a more visible texture or unevenness on its surface. The powder spreading roller rotates counterclockwise, while the compaction roller rotates clockwise. It is understood that the compaction roller should have a smooth surface, while the powder spreading roller should have a rough surface. The powder spreading roller with a high-roughness surface generates greater shear force when rotating counterclockwise, carrying excess powder forward and avoiding excessive downward pressure. The slightly smoother compaction roller, positioned slightly lower than the powder spreading roller, rotates clockwise. The smooth compaction roller generates greater downward pressure when rotating clockwise, compacting the loose powder. This compaction avoids horizontal shear force and horizontal displacement of the powder under high compaction, thus preventing problems such as powder pushing in various directions.
[0072] In one embodiment, the ratio of the density of the powder layer to the loose powder density is 1:(0.8-1.2), and the ratio of the density of the compacted powder layer to the tapped powder density is 1:(0.8-1.2), specifically related to the compactability of the powder. This reduces the adhesion and mixing of falling powder, lowers the powder spreading shear force and downward pressure, and ensures sufficient support strength for areas where powder not used in printing or where old powder layers are bonded, preventing damage during powder pushing.
[0073] To avoid excessive powder accumulation in front of the powder spreading module, in one embodiment, the bottom of the vibrating plate is higher than the bottom of the powder spreading roller, with a height difference of 0.5mm to 5mm, exemplarily 0.8mm, 1mm, 2mm, 3mm or 4mm, but not limited thereto.
[0074] To achieve a uniform powder density, in a preferred embodiment, the ratio of the thickness of the base powder layer to the thickness of each compacted powder layer is (20-40):1, that is, the compacted powder layer is laid 20-40 times to form the base powder layer; the ratio of the thickness of each compacted powder layer to the D50 of the powder is (2-10):1, and / or, the ratio of the thickness of each compacted powder layer to the D90 of the powder is (1.5-10):1.
[0075] Optionally, the powder's D50 is 10μm to 100μm, its D90 is 10μm to 100μm, and its angle of repose, either directly or after mixing with additives, is 35° to 60°. By controlling the powder's performance parameters, the powder achieves a certain degree of flowability and can overcome the formation of internal material arches. The angle of repose can be adjusted by factors such as the content of liquid additives within the powder, the powder's particle size, moisture content, and sphericity.
[0076] S5. Move the powder forming module to the initial position to complete the single-layer powder spreading.
[0077] In a preferred embodiment, as the powder forming module moves to the initial position, the residual powder near the powder spreading roller that did not participate in powder spreading falls into the residual powder collection device, avoiding cumulative errors in the next powder replenishment and spreading stage. Moreover, residual powder recovery can also avoid the dependence on precise control of the amount of powder used for replenishment, reducing the difficulty of replenishment. Specifically, the negative pressure of the residual powder recovery suction tube is -0.4MPa to -0.6MPa.
[0078] S6. Repeat S1 to S5 until the base powder layer is completed.
[0079] The base powder layer is a powder layer of a certain thickness formed on the printing platform. The application of the base powder layer can prevent the printed parts from sticking to the printing platform, and the density of each compacted powder layer can be stabilized through multiple layers. More importantly, the compacted base powder layer can provide sufficient support for the first inkjet area, avoiding powder pushing problems caused by the loose state of natural powder accumulation.
[0080] S7. Repeat S1 to S5 on the base powder layer to complete the laying of the slice layer. Control the inkjet module to follow the movement of the powder forming module, spray the binder and solidify the powder in the preset area of each slice layer until the printing of the model is completed and the 3D printed product is obtained.
[0081] Specifically, the preset path for the inkjet module movement is as follows: it moves along the Y direction, sprays adhesive and cures bonding powder in a preset area, and then moves a certain distance along the X direction and moves in the opposite direction along the Y direction, spraying adhesive and curing bonding powder in the preset area, thus achieving inkjet printing of each slice layer in segments.
[0082] In one embodiment, the inkjet module moves at a speed of 100 mm / s to 400 mm / s in the X direction, exemplarily 150 mm / s, 200 mm / s, 250 mm / s, 300 mm / s, or 350 mm / s, but is not limited thereto; and moves at a speed of 100 mm / s to 600 mm / s in the Y direction, exemplarily 150 mm / s, 200 mm / s, 300 mm / s, 400 mm / s, or 500 mm / s, but is not limited thereto. Through continuous segmented movement and scanning, the inkjet module completes inkjet printing across the entire print area.
[0083] In one embodiment, depending on the composition of the adhesive, the adhesive can be one or more of a two-component adhesive, a multi-component adhesive, and a one-component adhesive; depending on the solvent properties of the adhesive, the adhesive can be one or more of a water-based adhesive, an oil-based adhesive, and an alcohol-based adhesive; depending on the material of the adhesive, the adhesive can be an organic adhesive and / or an inorganic adhesive; depending on the excitation source of the adhesive, the adhesive can be one or more of a dry-curing adhesive, a thermosetting adhesive, a chemically reacting curing adhesive, and a UV-curing adhesive, and the specific selection can be made according to the type of powder and the required performance of the printed product.
[0084] In summary, the motion relationships and control logic of all modules are shown in Figure 10. In the entire printing system, the motion controller 100 is responsible for receiving printing instructions from the printing software and controlling each sub-motion controller. The main modules in the system perform linear, rotational, or vibrational motions within their set degrees of freedom, specifically controlled by each sub-motion controller, including the Z-axis linear motion controller 110, X-axis linear motion controller 120, Y-axis linear motion controller 130, R-axis rotational motion controller 140, W-axis vibrational motion controller 150, and F-axis flipping motion controller 160. Finally, each module performs the designed motion pattern 170 to complete the printing process. Specifically, the platform module 10 performs a lifting motion Z1 along the Z-axis, the inkjet module 20 performs a linear reciprocating motion Y1 along the inkjet scanning track 22, and performs a segmented scanning linear motion X1 along the toner spreading track 15. The toner spreading module 30 performs a scanning linear motion X2 along the toner spreading track 15, while its internal toner spreading roller 35 and compaction roller 34 perform opposite rotational motions R1 and R2, respectively. The powder-feeding module 40, fixed together with the powder-spreading module 30, also performs a scanning linear motion X2 along the powder-spreading track 15. Its internal powder-replenishing receiving plate 41 rotates F1 to control the working position of the powder. The eccentric wheel 42 rotates R3 along its axis, driving the vibrating plate 44 via the connecting rod 43 to improve the powder's flowability. The powder-replenishing module 60 performs a powder-replenishing linear motion Y2 along the powder-replenishing track 62. Its internal powder outlet vibrator 63 vibrates at high frequency W1, which, in conjunction with the rotational motion R4 of the belt drive shaft 65, drives the powder-replenishing belt 64 to carry the powder out of the temporary powder hopper 61 and onto the powder-replenishing receiving plate 41.
[0085] The specific process and operation are as follows.
[0086] Before inkjet printing begins, a base powder layer needs to be laid. The main purpose of this step is to pre-form a certain thickness of powder beneath the printed part, preventing the part from sticking to the printing platform and stabilizing the compaction density of each powder layer through multiple layers. More importantly, the compacted base powder layer provides sufficient support for the first inkjet area, preventing powder pushing problems caused by the loose state of natural powder accumulation. A schematic diagram of the base powder layer laying process is shown in Figure 11, with the specific operation logic being steps 301-305. First, in step 301, the printing platform rises to the top, the powder delivery module moves directly below the powder delivery module, the vibrating plate shuts off, and the inkjet module returns to the powder laying starting position to wait. Then, in step 302, the powder delivery module replenishes an appropriate amount of powder to the powder delivery module. Finally, in step 303, the printing platform descends by one layer thickness. Next, in step 304, the powder spreading module and the powder dropping module return to the powder spreading starting position and begin to move horizontally to the right. The vibrating plate starts to transport the powder to the front of the powder spreading roller. Through the sweeping action of the powder spreading roller and the compaction action of the compaction roller, the powder spreading action of one layer is completed. Finally, in step 305, the actions of steps 301 to 304 are repeated to complete the powder spreading of the bottom powder layer. For details, please refer to the working diagram.
[0087] First, as shown in Figure 4, the inkjet module 20 moves along the X-direction on the toner-spreading track 15 to the left of the platform module 10 to wait. The printing platform 12 moves downwards along the Z-direction to create space for toner spreading. The toner-spreading module 30 and the toner-dropping module 40 are fixed together and move along the X-direction to the right of the platform module 10 to prepare for toner replenishment. Once the toner-dropping receiving plate 41 rotates to a horizontal position, the belt drive shaft 65 in the toner-dropping module 60 begins to rotate, causing the toner-dropping belt 64 to rotate counterclockwise. Printing powder 50 is carried out of the toner-dropping module 60 along with the movement of the toner-dropping belt 64. At this time, the toner outlet vibrator 63 vibrates at a high frequency, forcing the low-flow-rate toner powder 51 to acquire a certain flowability and flow out from the temporary toner hopper 61 of the toner-dropping module 60. As the toner-dropping module 60 moves along the toner-dropping track 62 at a certain uniform speed in the Y-direction, a certain amount of uniformly dropped toner powder 52 is finally filled onto the toner-dropping receiving plate 41. The toner-dropping module 60 then stops replenishing toner and returns to its initial position.
[0088] Subsequently, as shown in Figure 5, the printing platform descends by one layer thickness, and then the powder spreading module 30 and the powder dropping module 40 move along the X direction to the left side of the platform module 10 to prepare for powder dropping. At this time, the powder receiving plate 41 rotates counterclockwise, and the powder 52 slides into the triangular area formed by the vibrating plate 44, the powder baffle 45, and the powder spreading roller 35.
[0089] Subsequently, as shown in Figure 6, the powder spreading module 30 and the powder falling module 40 move to the right along the X direction. During this movement, the eccentric wheel 42 drives the connecting rod 43 and the vibrating plate 44, forming a back-and-forth vibration along the vibration direction 47. The amplitude and frequency of the vibration are adjusted by the eccentricity and rotation speed of the eccentric wheel 42. With the assistance of this vibration, the low-flowability powder 52, which has re-agglomerated under gravity, regains better flowability and slides evenly in front of the powder spreading roller 35. Crucially, the powder's flowability is insufficient at this point to allow it to flow completely out, and it gradually slides down as the powder spreading module 30 and the powder falling module 40 move to the right. To avoid powder shortages or accumulation during powder spreading, the amplitude and / or frequency of the vibrating plate 44 need to be adjusted appropriately.
[0090] As the powder moves to the right along the X direction, the powder 52 is transferred from below the powder distribution module 40 to the printing platform 12, forming a flat, loose powder layer 53. The powder distribution roller 35 rotates along the powder distribution roller rotation direction 37 to level the powder layer. Subsequently, the powder layer 53 passes through the compaction roller 34, which rotates clockwise along the compaction roller rotation direction 36. Since the height of the compaction roller 34 is slightly lower than that of the powder distribution roller 35, the loose powder is compacted to form a compacted powder layer 54. As the powder distribution module 30 and the powder distribution module 40 move to the right, the powder distribution action across the entire printing area is gradually completed.
[0091] Afterwards, the powder spreading module 30 and the powder dropping module 40 move to the right side of the platform module 10 to prepare for the next layer of powder replenishment. The actions shown in Figures 4 to 6 are repeated until the powder layer of the specified height is completed, as shown in Figure 7. At this time, the excess powder is concentrated into excess powder 56 when passing through the excess powder collection box 13. Through the negative pressure of the excess powder recovery suction pipe 14, the excess powder 56 is recycled.
[0092] Then, the inkjet printing process begins, with the operational logic shown in Figure 12. Similar to the powder layer application process, inkjet printing requires steps such as powder replenishment, starting point preparation, and powder application. However, unlike other processes, after completing the powder replenishment actions in steps 401 and 402, in the lifting and lowering step 403, the printing platform descends not only by the thickness of one powder layer but also by an additional safety distance. In one embodiment, this safety distance is typically 2 to 10 times the thickness of the powder layer. This is to prevent residual powder on the powder layer rollers and compaction rollers from contacting the inkjet area of the previous compacted powder layer during the movement of the powder forming module from its initial position to the powder application start position, thus avoiding damage to the printed pattern and adhesive sticking to the rollers. Next, in the powder application step 404, the printing platform needs to rise by this safety distance before powder application can proceed. Then, after powder application, the inkjet process 405 follows. Finally, in step 406, steps 401 to 405 are repeated until all models are printed, as shown in Figures 8 and 9.
[0093] Since binder jetting selectively sprays binder layer by layer onto the powder bed to bond the powder and ultimately build a three-dimensional product, after each layer of powder is laid and compacted, the inkjet module moves horizontally along the Y direction, sprays binder in a specific area, and cures the bonded powder. Subsequently, the inkjet module moves horizontally a certain distance along the X direction and then moves horizontally in the opposite direction along the Y direction, spraying binder in a specific area and curing the bonded powder, thus achieving segmented inkjet printing of each compacted powder layer. As shown in Figure 8, the powder laying module 30 and the powder falling module 40 operate normally as shown in Figure 6, except that the inkjet module 20 moves to the right along the X direction to the left boundary of the printing platform 12. The inkjet head integration mechanism 23 then moves along the inkjet scanning track 22 in the Y direction. During this process, the inkjet head 24 sprays binder 25 in the designed area, forming a new powder layer bonding area 55. After completing the printing of this area, the inkjet module 20 moves to the right along the X direction a certain distance, and the inkjet head integration mechanism 23 moves in the opposite direction along the inkjet scanning track 22 to complete the inkjet printing of this area. As it moves and scans segment by segment to the right, the inkjet module 20 will complete the inkjet printing of the entire print area.
[0094] After the powder layer is laid and inkjet printing is completed, the system will re-enter the powder replenishment stage as shown in Figure 9. Similar to Figure 4, the system will repeat the actions of powder replenishment, powder application and inkjet printing as shown in Figures 4 to 8. The new powder layer bonding area 55 will bond with the old powder layer bonding area 58, and the layers will be stacked to form a three-dimensional printed blank. The new compacted powder layer 54 will also mix with the powder 57 that did not participate in the printing before and still remain in a non-bonded loose powder state. When the printed blank is taken out later, it will be recycled together for the next printing.
[0095] The present invention will be further described below with reference to specific embodiments:
[0096] Example 1
[0097] This embodiment provides a binder jetting 3D printing method for low-flowability powder, including the following steps:
[0098] S1. Control the movement of the powder forming module to reach the initial position; wherein, the powder forming module includes a powder dropping module and a powder spreading module, and the powder dropping module and the powder spreading module move synchronously.
[0099] The powder is non-spherical alumina powder with a D50 of 30μm and a powder repose angle of 45°. The printing platform measures 1200mm × 800mm × 800mm, with a Z-axis travel speed of 20mm / s. The residual powder collection box measures 1200mm × 200mm × 800mm, the residual powder recovery suction tube has a diameter of 50mm, and the negative pressure is -0.4MPa.
[0100] S2. Add a preset amount of powder to the powder dispensing module through the powder replenishment module. The powder dispensing module includes a powder replenishment receiving plate and a vibrating plate.
[0101] In the powder replenishment module, the vibration frequency of the vibrator is 100Hz, the width of the powder replenishment belt is 300mm, the diameter of the belt drive shaft is 60mm, and the rotational speed along the direction of the powder replenishment belt is 1r / s.
[0102] In the powder receiving module, the powder receiving plate is 1200mm long and 100mm wide, the eccentricity of the eccentric wheel is 1mm, and the vibration frequency of the vibrating plate along the vibration direction is 20Hz.
[0103] The amount of supplementary powder added to the powder-feeding module each time is 1.5 times the amount of powder required for each powder layer.
[0104] S3. Move the powder forming module to the powder spreading start position, and control the powder receiving plate to make the powder fall onto the vibrating plate.
[0105] S4. By controlling the vibration of the vibrating plate, the powder is transferred to the preset area in front of the powder spreading module, and then the powder spreading module is used to spread and compact it in sequence.
[0106] In the powder spreading module, the powder spreading speed along the X direction is 200 mm / s, and the idle stroke speed is 500 mm / s. The powder spreading module includes a powder spreading roller and a compaction roller. The powder spreading roller has a diameter of 60 mm and a surface roughness of Ra 25, and the compaction roller has a diameter of 60 mm and a surface roughness of Ra 1.0. The compaction roller rotates clockwise, and the powder spreading roller rotates counterclockwise. The height difference between the compaction roller and the powder spreading roller is 0.22 mm.
[0107] S5. Move the powder forming module to the initial position to complete the single-layer powder spreading.
[0108] S6. Repeat S1 to S5 until the base powder layer is completed.
[0109] S7. Repeat S1 to S5 on the base powder layer to complete the laying of the slice layer. The powder forming module moves horizontally in the X direction, lays powder on the base powder layer and compacts it to form a slice layer with a thickness of 0.2mm. After each slice layer is formed, the inkjet module sprays binder in a specific area of the layer and cures the powder. Repeat until the 3D printed product is obtained.
[0110] In the inkjet module, the inkjet module moves at a speed of 400 mm / s in the X direction and 500 mm / s in the Y direction. There are 8 inkjet heads, and the adhesive is epoxy resin.
[0111] Example 2
[0112] This embodiment provides a binder jetting 3D printing method for low-flowability powder, including the following steps:
[0113] S1. Control the movement of the powder forming module to reach the initial position; wherein, the powder forming module includes a powder dropping module and a powder spreading module, and the powder dropping module and the powder spreading module move synchronously.
[0114] The powder is natural quartz sand powder with a D50 of 70μm and a powder repose angle of 42°. The printing platform measures 2500mm × 1500mm × 1000mm, with a Z-axis moving speed of 20mm / s. The residual powder collection box measures 2500mm × 400mm × 400mm, the residual powder recovery suction tube has a diameter of 80mm, and the negative pressure is -0.5MPa.
[0115] S2. Add a preset amount of powder to the powder dispensing module through the powder replenishment module. The powder dispensing module includes a powder replenishment receiving plate and a vibrating plate.
[0116] In the powder replenishment module, the vibration frequency of the vibrator is 120Hz, the width of the powder replenishment belt is 400mm, the diameter of the belt drive shaft is 50mm, and the rotational speed along the direction of the powder replenishment belt is 2r / s.
[0117] In the powder receiving module, the powder receiving plate is 2500mm long and 120mm wide, the eccentricity of the eccentric wheel is 3mm, and the vibration frequency of the vibrating plate along the vibration direction is 10Hz.
[0118] The amount of supplementary powder added to the powder-feeding module each time is 1.8 times the amount of powder required for each powder layer.
[0119] S3. Move the powder forming module to the powder spreading start position, and control the powder receiving plate to make the powder fall onto the vibrating plate.
[0120] S4. By controlling the vibration of the vibrating plate, the powder is transferred to the preset area in front of the powder spreading module, and then the powder spreading module is used to spread and compact it in sequence.
[0121] In the powder spreading module, the powder spreading speed along the X direction is 300 mm / s, and the idle stroke speed is 500 mm / s. The powder spreading module includes a powder spreading roller and a compaction roller. The powder spreading roller has a diameter of 60 mm and a surface roughness of Ra 12.5, while the compaction roller has a diameter of 120 mm and a surface roughness of Ra 0.6. The compaction roller rotates clockwise, and the powder spreading roller rotates counterclockwise. The height difference between the compaction roller and the powder spreading roller is 0.3 mm.
[0122] S5. Move the powder forming module to the initial position to complete the single-layer powder spreading.
[0123] S6. Repeat S1 to S5 until the base powder layer is completed.
[0124] S7. Repeat S1 to S5 on the base powder layer to complete the laying of the slice layer. The powder forming module moves horizontally in the X direction, lays powder on the base powder layer and compacts it to form a slice layer with a thickness of 0.4mm. After each slice layer is formed, the inkjet module sprays binder in a specific area of the layer and cures the powder. Repeat until the 3D printed product is obtained.
[0125] In the inkjet module, the inkjet module moves at a speed of 400 mm / s in the X direction and 600 mm / s in the Y direction. There are 12 inkjet heads, and the adhesive is a silicate inorganic adhesive.
[0126] Example 3
[0127] This embodiment provides a binder jetting 3D printing method for low-flowability powder, including the following steps:
[0128] S1. Control the movement of the powder forming module to reach the initial position; wherein, the powder forming module includes a powder dropping module and a powder spreading module, and the powder dropping module and the powder spreading module move synchronously.
[0129] The powder is 316L stainless steel fine powder with a D50 of 10μm and a powder repose angle of 46°. The printing platform measures 800mm × 500mm × 400mm, with a Z-axis moving speed of 10mm / s. The residual powder collection box measures 800mm × 100mm × 300mm, the residual powder recovery suction tube has a diameter of 30mm, and the negative pressure is -0.5MPa.
[0130] S2. Add a preset amount of powder to the powder dispensing module through the powder replenishment module. The powder dispensing module includes a powder replenishment receiving plate and a vibrating plate.
[0131] In the powder replenishment module, the vibration frequency of the vibrator is 10Hz, the width of the powder replenishment belt is 200mm, the diameter of the belt drive shaft is 30mm, and the rotational speed along the direction of the powder replenishment belt is 3r / s.
[0132] In the powder receiving module, the powder receiving plate is 800mm long and 40mm wide, the eccentricity of the eccentric wheel is 1mm, and the vibration frequency of the vibrating plate along the vibration direction is 10Hz.
[0133] The amount of supplementary powder added to the powder-feeding module each time is twice the amount of powder required for each powder layer.
[0134] S3. Move the powder forming module to the powder spreading start position, and control the powder receiving plate to make the powder fall onto the vibrating plate.
[0135] S4. By controlling the vibration of the vibrating plate, the powder is transferred to the preset area in front of the powder spreading module, and then the powder spreading module is used to spread and compact it in sequence.
[0136] In the powder spreading module, the powder spreading speed along the X direction is 100 mm / s, and the idle stroke speed is 300 mm / s. The powder spreading module includes a powder spreading roller and a compaction roller. The powder spreading roller has a diameter of 50 mm and a surface roughness of Ra 12.5, and the compaction roller has a diameter of 50 mm and a surface roughness of Ra 0.25. The compaction roller rotates clockwise, and the powder spreading roller rotates counterclockwise. The height difference between the compaction roller and the powder spreading roller is 0.05 mm.
[0137] S5. Move the powder forming module to the initial position to complete the single-layer powder spreading.
[0138] S6. Repeat S1 to S5 until the base powder layer is completed.
[0139] S7. Repeat S1 to S5 on the base powder layer to complete the laying of the slice layer. The powder forming module moves horizontally in the X direction, lays powder on the base powder layer and compacts it to form a slice layer with a thickness of 0.1mm. After each slice layer is formed, the inkjet module sprays binder in a specific area of the layer and cures the powder. Repeat until the 3D printed product is obtained.
[0140] In the inkjet module, the inkjet module moves at a speed of 200 mm / s in the X direction and 400 mm / s in the Y direction. There are 12 inkjet heads, and the adhesive is a water-based adhesive.
[0141] Examples 1 to 3 were tested using the following methods:
[0142] (1) Powder layer density W p Take a sample from the powder layer and calculate the density of the powder layer according to the following formula;
[0143] The process involves placing the sampled product on a measuring platform and measuring its weight in the air, denoted as W1; then placing the sampled product in the measuring platform after waterproofing treatment and measuring its weight in the air, denoted as W2; and finally placing the waterproofed sampled product in water and measuring its weight in the water, denoted as W3.
[0144] (2) Density of compacted powder layer W y Take a sample from the compacted powder layer and calculate the density of the compacted powder layer according to the following formula;
[0145] The process involves placing the sampled product on a measuring platform and measuring its weight in the air, denoted as W4; then placing the sampled product in the measuring platform after waterproofing treatment and measuring its weight in the air, denoted as W5; and finally placing the waterproofed sampled product in water and measuring its weight in the water, denoted as W6.
[0146] (3) Printing efficiency: Calculate the printing efficiency according to the following formula;
[0147] (4) Printing space density difference RSD: Take samples at different positions on the printing platform (more than 9 samples), calculate the printing density at different positions, and calculate the printing space density difference according to the following formula;
[0148] The standard deviation of the printing density of products sampled from different locations is calculated and denoted as W. s Calculate the arithmetic mean of the printing density of products sampled from different locations, denoted as W. x The calculation method for the printing density of products sampled from different locations is the same as that for the density of the powder layer and the density of the compacted powder layer.
[0149] The specific test results are as follows:
[0150] The above description is a preferred embodiment of the invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the invention, and these improvements and modifications are also considered to be within the scope of protection of the invention.
Claims
1. A binder jetting 3D printing method for low-flowability powder, characterized in that, Includes the following steps: (1) Control the movement of the powder forming module to reach the initial position; wherein, the powder forming module includes a powder dropping module and a powder spreading module, and the powder dropping module and the powder spreading module move synchronously; (2) A preset amount of powder is added to the powder dispensing module through the powder replenishment module, wherein the powder dispensing module includes a powder replenishment receiving plate and a vibrating plate; (3) Move the powder forming module to the powder spreading start position, and control the powder receiving plate to make the powder fall onto the vibrating plate; (4) By controlling the vibration of the vibrating plate, the powder is transferred to a preset area in front of the powder spreading module, and then the powder spreading module is used to spread and compact the powder in sequence. (5) Move the powder forming module to the initial position to complete the single-layer powder spreading; (6) Repeat steps (1) to (5) until the base powder layer is laid; (7) Repeat steps (1) to (5) on the base powder layer to complete the laying of the slice layer. Control the inkjet module to follow the movement of the powder forming module, spray the binder and solidify the powder in the preset area of each slice layer until the printing of the model is completed and the 3D printed product is obtained.
2. The binder jetting 3D printing method for low-flowability powder as described in claim 1, characterized in that, The powder forming module also includes a support frame, the powder dropping module includes a powder receiving plate and a vibrating plate, and the powder spreading module includes a powder spreading roller and a compacting roller. The powder receiving plate, vibrating plate, powder spreading roller and compacting roller are all fixed on the support frame. The vibrating plate is located in front of the powder spreading roller, and the compacting roller is located behind the powder spreading roller. There is a preset distance between the vibrating plate and the powder spreading roller to form a preset area for powder transfer.
3. The binder jetting 3D printing method for low-flowability powder as described in claim 2, characterized in that, The powder spreading roller is used to sweep up the powder scattered by the powder falling module to obtain a powder spreading layer. The ratio of the density of the powder spreading layer to the loose density of the powder is (0.8~1.2):
1. The compaction roller is used to compact the powder layer to obtain a compacted powder layer, and the ratio of the density of the compacted powder layer to the density of the powder is (0.8~1.2):
1.
4. The binder jetting 3D printing method for low-flowability powder as described in claim 3, characterized in that, The ratio of the thickness of the base powder layer to the thickness of each compacted powder layer is (20-40):1; The ratio of the thickness of each compacted powder layer to the D50 of the powder added by the powder replenishment module is (2-10):1, and / or the ratio of the thickness of each compacted powder layer to the D90 of the powder added by the powder replenishment module is (1.5-10):
1.
5. The binder jetting 3D printing method for low-flowability powder as described in claim 4, characterized in that, The powder has a D50 of 10 μm to 100 μm, and / or the powder has a D90 of 10 μm to 100 μm; The powder has an angle of repose of 35° to 60°.
6. The binder jetting 3D printing method for low-flowability powder as described in claim 2, characterized in that, The bottom of the vibrating plate is higher than the bottom of the powder spreading roller, and the height difference between the vibrating plate and the powder spreading roller is 0.5mm to 5mm. The compaction roller and the powder spreading roller rotate in opposite directions. The surface roughness of the compaction roller is less than that of the powder spreading roller. The bottom of the powder spreading roller is higher than the bottom of the compaction roller. The height difference between the powder spreading roller and the compaction roller is 0.01 mm to 1 mm. Both the powder receiving plate and the vibrating plate are rotatable relative to the support; the vibration frequency of the vibrating plate is 0.1Hz to 100Hz. During the process of adding powder from the powder replenishing module to the powder falling module, the powder replenishing receiving plate is in a horizontal position; during the powder spreading process, the powder replenishing receiving plate has an angle with the horizontal direction so that the powder on the powder replenishing receiving plate falls onto the vibrating plate.
7. The binder jetting 3D printing method for low-flowability powder as described in claim 6, characterized in that, The compaction roller has a diameter of 25mm to 120mm and a surface roughness of Ra 0.25 to Ra 3.
2. The powder spreading roller has a diameter of 25mm to 120mm and a surface roughness of Ra 1.6 to Ra 100.
8. The binder jetting 3D printing method for low-flowability powder as described in claim 3, characterized in that, The preset path for the movement of the inkjet module is as follows: it moves along the Y direction, sprays adhesive and cures bonding powder in a preset area, and then moves a certain distance along the X direction and moves in the opposite direction along the Y direction, sprays adhesive and cures bonding powder in the preset area, and realizes inkjet printing of each slice layer in segments. The inkjet module moves at a speed of 100 mm / s to 400 mm / s in the X direction and at a speed of 100 mm / s to 600 mm / s in the Y direction.
9. The binder jetting 3D printing method for low-flowability powder as described in claim 3, characterized in that, During the powder spreading process, the powder forming module moves at a speed of 50 mm / s to 400 mm / s in the X direction; The empty travel speed of the powder forming module from the initial position to the powder spreading start position is 250 mm / s to 500 mm / s; The powder replenishing module is equipped with a powder outlet vibrator and a powder replenishing belt. The powder replenishing in the powder replenishing module flows out under the action of the powder outlet vibrator. Through the rotation of the powder replenishing belt and the movement of the powder replenishing module in the Y direction, the preset amount of powder is evenly sprinkled on the powder replenishing receiving plate. The preset amount of powder added by the powder replenishing module to the powder falling module each time is 1 to 2 times the amount of powder required for each powder layer.
10. A binder jetting 3D printing apparatus for low-flowability powder, used to perform the binder jetting 3D printing method for low-flowability powder as described in any one of claims 1 to 9, characterized in that, It includes a powder replenishment module, a powder forming module, an inkjet module, and a platform module; The platform module includes a printing platform, and the printing platform is equipped with a lifting mechanism. The lifting mechanism is connected to the printing platform and is used to drive the printing platform to move up and down in the Z direction. The powder forming module and the inkjet module are positioned above the platform module along the X direction; the powder forming module includes a powder dropping module and a powder spreading module that move synchronously; the powder dropping module includes a powder receiving plate and a vibrating plate for vibrating and scattering powder; the powder spreading module includes a powder spreading roller and a compacting roller for spreading and compacting the powder scattered by the powder dropping module; the inkjet module is used to spray adhesive into a preset area of the slice layer; The powder replenishment module is located on one side of the platform module and is higher than the powder dropping module, and is used to replenish the powder dropping module.