An ink circulation system for a 3D printing device and a 3D printing device

Abstract

The application discloses an ink circulating system for a 3D printing device and a 3D printing device, and aims to solve the problems of ink supply pressure fluctuation and surge. The system comprises a first ink bottle, a second ink bottle, a printing head, an ink supply and discharge system and a negative pressure device which are of the same structure. The negative pressure device provides different negative pressures for the two ink bottles, so that the pressure of the first ink bottle is higher than that of the second ink bottle, thereby driving the directional flow of the ink. Each ink bottle comprises a bottle body, a top negative pressure interface, a middle anti-surge sheet, a lower barrier sheet, a liquid level detection device, a bottom printing head connecting interface and an external ink interface. The anti-surge sheet is matched with the bottle wall gap and is provided with micropores, and the barrier sheet is also provided with micropores. Through the double damping structure in the bottle, the ink shaking and vortex caused by movement and the bubbles or oscillation generated by the flow of the ink are effectively inhibited, so that the printing head stably discharges the ink, and the system reliability, assembly convenience and operation continuity are improved.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, and more specifically to an ink circulation system for 3D printing equipment and 3D printing equipment. Background Technology

[0002] Microdroplet inkjet 3D printing is an advanced additive manufacturing technology that precisely jets materials such as liquid photosensitive resin into a forming platform in the form of micron-sized droplets, and then solidifies and deposits them layer by layer to create three-dimensional solids. The printing quality, accuracy, and reliability of this technology are highly dependent on the stability of droplet jetting, and the stable formation and jetting of droplets are closely related to the stability of the fluid pressure inside the print head.

[0003] When the printhead moves at high speed, the ink in the ink path is prone to violent shaking (surge), which causes the internal pressure of the printhead to fluctuate drastically, directly affecting the stability of droplet formation and the accuracy of jetting, resulting in a decline in print quality.

[0004] To suppress surges, existing technologies typically add accessories such as dampers and accumulators to the ink circulation system. This undoubtedly increases the complexity and assembly difficulty of the system, and occupies valuable internal space of the equipment.

[0005] To address the aforementioned issues, Chinese invention patent CN223493893U discloses an "Ink Circulation Architecture for a 3D Printer, a 3D Printer and its Control System." This solution achieves ink circulation by setting up an ink inlet chamber, an ink return chamber, a flow ink path, and a negative pressure air path, and utilizes an auxiliary negative pressure air box to buffer airflow oscillations during negative pressure adjustment. This solution improves system integration and controllability to some extent. However, by adding an auxiliary negative pressure air box to buffer airflow oscillations and air bubbles during negative pressure adjustment, it can only reduce the instability caused by negative pressure changes, but cannot alleviate ink oscillations or air bubble generation caused by the shaking of the device itself.

[0006] Therefore, there is an urgent need in the field for an ink supply circulation system that can fundamentally suppress oscillations, surges, and bubbles generated during ink circulation and is easy to assemble. Summary of the Invention

[0007] The purpose of this invention is to develop an ink circulation system for 3D printing equipment and a 3D printing equipment, thereby providing an ink supply circulation system that can fundamentally suppress vibrations and bubbles generated during ink circulation.

[0008] This invention is achieved through the following technical solution: An ink circulation system for a 3D printing device includes: First ink bottle and second ink bottle; The printhead includes an ink ejector, an inlet for communicating with the first ink bottle, and an outlet for communicating with the second ink bottle; The ink supply and discharge system includes an ink supply pump connected to the first ink bottle and an ink discharge pump connected to the second ink bottle, as well as an ink storage container for supplying ink to the ink supply pump and receiving ink discharged by the ink discharge pump. The negative pressure device provides different negative pressures to the first ink bottle and the second ink bottle respectively, so that the pressure in the first ink bottle is higher than the pressure in the second ink bottle. Both the first ink bottle and the second ink bottle include: Bottle body; A negative pressure interface is located at the top of the bottle body and is used to connect the negative pressure device; A surge protector is disposed in the middle of the inner cavity of the bottle, and a plurality of first micro-holes are distributed thereon. The diameter of the surge protector is smaller than the inner diameter of the bottle so that the surge protector fits the inner wall of the bottle with a clearance. A liquid level detection device is installed on the bottle body to detect the liquid level inside the bottle; A barrier sheet is disposed in the lower part of the inner cavity of the bottle, and multiple second micropores are distributed thereon; A printhead connection interface is located at the bottom of the bottle body and is used to connect the printhead; An external ink interface is located at the bottom of the bottle body and is used to connect the ink supply pump or the ink discharge pump.

[0009] The advantages of the above technical solution are as follows: Separate first and second ink bottles are provided, allowing for independent assembly or replacement, thus improving the flexibility of the ink circulation system assembly; the ink supply and discharge system achieves cyclical ink supply and recovery; the negative pressure device provides different pressures to the two ink bottles, ensuring a stable flow of ink from the first ink bottle to the printhead, and allowing excess ink to flow smoothly back to the second ink bottle after the printhead completes ejection, effectively maintaining pressure balance inside the printhead; the surge protector inside the ink bottle is fitted with a gap (e.g., an annular gap between it and the inner wall of the bottle), and the surge protector has multiple first micro-holes distributed on it, which, when the printhead operates... During operation, the surge protector effectively suppresses the violent sloshing (surge phenomenon) of ink caused by inertia. Its microporous design allows for normal ink flow while also damping fluid movement, significantly reducing pressure fluctuations and eliminating air bubbles. The liquid level detection device monitors the liquid level in the bottle in real time, providing precise data for starting and stopping the ink supply and discharge pumps, preventing dry-running or overflowing of the ink bottle, and ensuring the safety and continuity of system operation. The baffle plate located at the bottom of the bottle slows the flow of ink into or out of the bottom area, effectively eliminating vortices, water columns, and air bubbles generated when ink enters or exits from the bottom, thus avoiding localized pressure disturbances. The first micropores on the surge protector and the second micropores on the baffle plate are densely distributed and can be formed by laser processing.

[0010] In one feasible embodiment, the first ink bottle is equipped with a heating device for heating it; the heating device can actively control the temperature of the ink in the first ink bottle. By precisely adjusting the heating power, the ink temperature can be stably controlled within its optimal operating range (25℃~35℃), effectively improving its fluidity and ensuring smooth flow of ink in the ink supply line and printhead. This avoids problems such as insufficient ink supply, broken ink lines, or nozzle clogging caused by increased viscosity, thereby ensuring the consistency and stability of droplet ejection and improving print quality. Furthermore, the heating device includes a flexible silicone heating film surrounding the outer periphery of the first ink bottle, and the flexible silicone heating film is connected to a temperature controller. In one feasible embodiment, the liquid level detection device includes a capacitive liquid level sensor or an optical liquid level sensor.

[0011] Furthermore, the liquid level detection device located in the first ink bottle is electrically connected to the ink supply pump, and the liquid level detection device located in the second ink bottle is electrically connected to the ink discharge pump. The electrical connection method includes connecting to the same controller or microprocessor via wires. This allows the start and stop of the ink supply pump and the ink discharge pump to depend on the output signal of the liquid level detection device, thereby maintaining the ink level in the ink bottle within a set range through timely ink supply and discharge. For example, when the liquid level detection device in the first ink bottle detects that the liquid level is below a set lower limit, the ink supply pump is activated to draw ink from the ink storage container to replenish the first ink bottle, stopping when the set upper limit is reached. When the liquid level in the second ink bottle reaches the upper limit, the ink discharge pump is activated to draw a portion of its ink into the ink storage container, stopping when the set lower limit is reached. This achieves automatic ink balance in the system. In one feasible embodiment, a downwardly extending connecting frame is connected to the top of the bottle body, and the radial ends of the surge protector are respectively connected to a connecting frame, so that the surge protector is suspended in the middle of the inner cavity of the bottle body. In one feasible embodiment, the total height of the bottle is H, and the height of the barrier relative to the bottom of the bottle is 0.1H-0.2H. In another feasible embodiment, the negative pressure device controls the pressure inside the first ink bottle to be between -5kPa and 0kPa, and controls the negative pressure inside the second ink bottle to be between -7kPa and -2kPa.

[0012] The present invention also provides a 3D printing device, including the ink circulation system for the 3D printing device described above. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the circulation principle of the ink supply circulation system in an embodiment of the present invention; Figure 2 This is an isometric view of the first ink bottle or the second ink bottle in an embodiment of the present invention; Figure 3 This is a cross-sectional view of the first ink bottle or the second ink bottle in an embodiment of the present invention.

[0014] In the diagram: 1. First ink bottle; 2. Second ink bottle; 3. Printhead; 4. Surge protector; 41. Connector; 5. Liquid level detection device; 6. Barrier plate; 7. Negative pressure interface; 8. Printhead connection interface; 9. External ink interface; 10. Heating device; 11. Ink supply pump; 12. Ink discharge pump; 13. Negative pressure device; 14. Second micro-orifice; 15. Annular gap; 16. First micro-orifice. Detailed Implementation

[0015] First, those skilled in the art should understand that the following embodiments are merely used to explain the technical principles of the embodiments of this application and are not intended to limit the scope of protection of the embodiments of this application. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0016] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" or "linked" should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral connection; it can refer to a mechanical connection or an electrical connection; it can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0017] In the embodiments of this application, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0018] To make the objectives, features and advantages of the present invention more apparent and understandable, specific embodiments are described in detail below with reference to the accompanying drawings.

[0019] like Figures 1 to 3 As shown, this embodiment provides an ink circulation system for a 3D printing device, which mainly includes a first ink bottle 1, a second ink bottle 2, a print head 3, an ink supply and discharge system (including an ink supply pump 11, an ink discharge pump 12 and connected pipes, as well as an ink storage container for supplying ink to the ink supply pump 11 and accommodating the ink discharged by the ink discharge pump 12), and a negative pressure device 13.

[0020] The first ink bottle 1 and the second ink bottle 2 have different functions in the system (one is an ink supply bottle and the other is a recycling bottle). They are connected in series through a print head 3, which includes an ink nozzle, an inlet for communicating with the first ink bottle 1, and an outlet for communicating with the second ink bottle 2.

[0021] The ink supply and discharge system includes an ink supply pump 11 connected to the first ink bottle 1 and an ink discharge pump 12 connected to the second ink bottle 2, as well as an ink storage container that supplies ink to the ink supply pump 11 and contains the ink discharged by the ink discharge pump 12. The negative pressure device 13 provides different negative pressures to the first ink bottle 1 and the second ink bottle 2, so that the pressure inside the first ink bottle 1 is higher than the pressure inside the second ink bottle 2.

[0022] Both the first ink bottle 1 and the second ink bottle 2 have the following structure: A roughly cylindrical bottle has a negative pressure port 7 at its top, which is connected to an external negative pressure device 13 via a pipe. The negative pressure device 13 can provide independently adjustable negative pressure to the first ink bottle 1 and the second ink bottle 2 respectively. In this embodiment, the negative pressure device 13 is set to make the pressure in the first ink bottle 1 -3 kPa and the pressure in the second ink bottle 2 -4 kPa. Since the pressure in the first ink bottle 1 (-3 kPa) is higher than the pressure in the second ink bottle 2 (-4 kPa), driven by this pressure difference, ink can flow stably from the first ink bottle 1 through the printhead 3 and into the second ink bottle 2.

[0023] A near-horizontal anti-surge plate 4 is disposed in the middle of the inner cavity of the bottle. This anti-surge plate 4 is preferably a thin, circular plate, suspended within the bottle body by a connecting frame 41. Specifically, the upper end of the connecting frame 41 is connected to the top of the bottle body, and both radial ends of the anti-surge plate 4 are connected to the lower end of the connecting frame 41 to maintain its positional stability. The anti-surge plate 4 has a densely distributed number of first micro-holes 16 processed by laser. Crucially, the diameter of the anti-surge plate 4 is smaller than the inner diameter of the bottle body, creating an annular gap 15 between its circumferential edge and the inner wall of the bottle. This composite structure of "micro-holes + annular gap" is the core of surge suppression: when the ink inside the bottle experiences violent overall shaking due to surges or equipment movement, this structure can effectively cut, dampen, and guide it, transforming large-scale liquid surface sloshing into gentle turbulence through the micro-holes and gaps, thereby greatly attenuating pressure fluctuations.

[0024] A liquid level detection device 5 (such as a capacitive liquid level sensor) is installed on the side wall of the bottle to monitor the liquid level of the ink in the bottle in real time.

[0025] A baffle plate 6 is horizontally mounted in the lower part of the bottle's inner cavity. The baffle plate 6 is located above the bottom of the bottle, and the total height of the bottle is H. The height of the baffle plate 6 relative to the bottom of the bottle is 0.1H-0.2H. The baffle plate 6 is also machined with densely distributed second micropores 14. The opening ratio and pore size of these second micropores are different from the first micropores 16 on the surge protector 4 (for example, the first micropore 16 has a pore size of 0.5-1 mm and an opening ratio of 30%-40%; the second micropore has a pore size of 1-2 mm and an opening ratio of 50%-60%), to provide a more suitable damping effect for the fluid at the bottom. The function of the baffle plate 6 is to make the ink flow into and out of the ink bottle from the bottom smoother, preventing the formation of suction vortices or direct water jets at the inlet and outlet, thereby avoiding the generation of air bubbles and additional pressure pulsations.

[0026] The bottom of the bottle has a printhead connection interface 8 facing downwards. This interface is preferably a quick-connect sealing connector, used for direct and tight connection with the inlet or outlet of the printhead 3, greatly shortening the flow channel length. An external ink interface 9 is located on the side of the bottom of the bottle. The external ink interface 9 of the first ink bottle 1 is connected to the ink supply pump 11 for replenishing new ink; the external ink interface 9 of the second ink bottle 2 is connected to an external ink discharge pump 12 for recovering excess ink.

[0027] Regarding control logic: A liquid level detection device 5 located in the first ink bottle is electrically connected to the ink supply pump 11, used to control the start and stop of the ink supply pump 11 according to the liquid level in the first ink bottle. A liquid level detection device 5 located in the second ink bottle 2 is electrically connected to the ink discharge pump 12, used to control the start and stop of the ink discharge pump 12 according to the liquid level in the second ink bottle 2. The electrical connection method includes connecting to the same controller or microprocessor via a wire. For example, when the liquid level detection device 5 in the first ink bottle 1 detects that the liquid level is below a set lower limit, the ink supply pump 11 is activated to draw ink from the ink storage container to replenish the first ink bottle 1, stopping when the set upper limit is reached. When the liquid level in the second ink bottle 2 reaches the upper limit, the ink discharge pump 12 is activated to draw out a portion of the ink and discharge it into the ink storage container, stopping when the set lower limit is reached. This achieves automatic ink balance in the system. This cycle ensures that the printhead 3 always receives a stable, continuous, and constant-pressure ink supply.

[0028] To further improve system performance, a flexible silicone heating film 10 can be wrapped around the outer periphery of the first ink bottle 1 as a heating device and connected to a temperature controller. This can precisely maintain the ink temperature at the ink supply end within the optimal operating range of 25℃~35℃, ensuring constant viscosity and good flowability.

[0029] The working process of this system: During printing, driven by negative pressure difference, ink flows from the bottom of the first ink bottle 1, enters the printhead 3 through the printhead connection interface 8, and participates in the ejection process. Residual ink flows out of the printhead 3 and enters the second ink bottle 2 through the printhead connection interface 8. Throughout this process, regardless of the movement of the printhead 3, the anti-surge plate 4 and the barrier plate 6 inside both ink bottles continuously and effectively suppress any disturbances in the ink, ensuring extremely stable pressure at the inlet of the printhead 3. The coordinated operation of the liquid level detection device 5, the ink supply pump 11, and the ink discharge pump 12 ensures stable ink volume.

[0030] The present invention also provides an embodiment of a 3D printing apparatus, which includes an ink circulation system for a 3D printing apparatus as described above.

[0031] In the description of the embodiments of this application, it should be noted that the terms "inner" and "outer" and other terms indicating direction or positional relationship are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and does not indicate or imply that the device or component must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this application.

[0032] In the description of this application, the terms "this embodiment" or "an embodiment," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, mechanisms, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0033] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An ink circulation system for a 3D printing device, characterized in that, include: First ink bottle (1) and second ink bottle (2); The printhead (3) includes an ink nozzle, an inlet for communicating with a first ink bottle (1), and an outlet for communicating with a second ink bottle (2). The ink supply and discharge system includes an ink supply pump (11) connected to the first ink bottle (1) and an ink discharge pump (12) connected to the second ink bottle (2), as well as an ink storage container for supplying ink to the ink supply pump (11) and accommodating the ink discharged by the ink discharge pump (12); The negative pressure device (13) provides different negative pressures to the first ink bottle (1) and the second ink bottle (2) respectively, so that the pressure inside the first ink bottle (1) is higher than the pressure inside the second ink bottle (2); Both the first ink bottle (1) and the second ink bottle (2) include: Bottle body; A negative pressure port (7) is located at the top of the bottle and is used to connect the negative pressure device (13). Surge protector (4) is located in the middle of the inner cavity of the bottle, and has a plurality of first microholes (16) distributed thereon. The diameter of the surge protector (4) is smaller than the inner diameter of the bottle so that the surge protector (4) fits the inner wall of the bottle with a gap. A liquid level detection device (5) is installed on the bottle body and is used to detect the liquid level inside the bottle; A barrier sheet (6) is provided in the lower part of the inner cavity of the bottle, and a plurality of second micropores (14) are distributed thereon. A printhead connection interface (8) is located at the bottom of the bottle body and is used to connect the printhead (3). An external ink interface (9) is located at the bottom of the bottle body and is used to connect the ink supply pump (11) or the ink discharge pump (12).

2. The ink circulation system for 3D printing equipment according to claim 1, characterized in that: The first ink bottle (1) is equipped with a heating device for heating it.

3. The ink circulation system for 3D printing equipment according to claim 2, characterized in that: The heating device includes a flexible silicone heating film (10) surrounding the outer periphery of the first ink bottle (1), and the flexible silicone heating film (10) is connected to a temperature controller.

4. The ink circulation system for 3D printing equipment according to claim 1, characterized in that: The liquid level detection device (5) includes a capacitive liquid level sensor or an optical liquid level sensor.

5. The ink circulation system for a 3D printing device according to claim 1 or 4, characterized in that: The liquid level detection device located in the first ink bottle (1) is electrically connected to the ink supply pump (11), and the liquid level detection device located in the second ink bottle (2) is electrically connected to the ink discharge pump (12).

6. The ink circulation system for a 3D printing device according to claim 1, characterized in that: The top of the bottle is connected to a downwardly extending connecting frame (41), and the two radial ends of the anti-surge plate (4) are respectively connected to a connecting frame (41), so that the anti-surge plate (4) is suspended in the middle of the inner cavity of the bottle.

7. The ink circulation system for a 3D printing device according to claim 1, characterized in that: The total height of the bottle is H, and the height of the barrier (6) relative to the bottom of the bottle is 0.1H-0.2H.

8. The ink circulation system for a 3D printing device according to claim 1, characterized in that: The negative pressure device (13) controls the pressure in the first ink bottle (1) to be from -5kPa to 0kPa, and controls the negative pressure in the second ink bottle (2) to be from -7kPa to -2kPa.

9. A 3D printing device, characterized in that: Includes an ink circulation system for a 3D printing device as described in any one of claims 1-8.

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