Circulating ink supply system for 3D ink-jet printing and control method thereof, and circulating ink supply device

Abstract

Disclosed in the present invention are a circulating ink supply system for 3D ink-jet printing and a control method thereof, wherein the circulating ink supply system comprises an ink-jet printing head, a circulation module, a heating element, and a power module. The circulation module is heated by the heating element to enable high-temperature phase change ink or high-viscosity ink to have better fluidity, and circulation kinetic energy is provided by the power module, so that the circulation module achieves circulation of the fluid. Also disclosed in the present invention is an integrated design of an integrated ink-jet printing circulating ink supply device, wherein most components and modules are arranged in a heating cavity having a heating function, a fluid passage is achieved by heating an internal flow channel of the heating cavity, and by means of heat conduction, it is ensured that the temperature the entire circulation system is uniform and the high-temperature phase change material is in a molten state, thereby achieving high-flow printing. Due to the integrated structural design, the structure is more compact, the cost is low, maintenance is easy, and the heating design is more concise and concentrated, thereby ensuring the temperature uniformity of fluid.

Description

Circulating ink supply system for 3D inkjet printing, control method thereof, and circulating ink supply device Technical Field

[0001] The present application belongs to the field of 3D printing, and specifically relates to a circulating ink supply system that supports high-flow, high-temperature, and high-viscosity phase change printing materials, an integrated inkjet printing circulating ink supply device, and a circulating ink supply method thereof. Background Art

[0002] 3D printers construct three-dimensional models through additive manufacturing methods. A wax 3D printer is a type of additive manufacturing equipment. It uses purple wax as the printing material and white wax as the support material. The wax material, which is heated to a high temperature and becomes liquid, is sprayed onto the printing platform. The wax material then solidifies at room temperature and is stacked layer by layer to create the model. Due to the advantages of high precision and smooth surfaces offered by wax-jet 3D printed models, wax-jet 3D printers are widely used in the jewelry, aerospace, engine, and other manufacturing industries. The printing materials used in wax-jet 3D printers are white wax and purple wax. The wax material is placed in a container, which is then loaded into an ink supply assembly. The wax in the container flows into the ink supply assembly and, after being heated at high temperature, flows into the inkjet print head. The inkjet print head prints the wax material layer by layer onto the print panel to create a three-dimensional model.

[0003] Typically, a circulation structure is provided within the ink supply system. Existing circulation structures typically include an ink supply cartridge and an ink return cartridge. The printing material in the ink supply cartridge enters the inkjet print head through a circulating ink supply pump, and then flows from the inkjet print head to the ink return cartridge, thereby achieving a circulating flow of the printing material. However, for wax-based 3D printers, the printing material is wax, which has a high viscosity. It is a high-viscosity, high-temperature phase-change material with poor fluidity. Uneven temperatures can easily cause blockages within the circulation structure, slowing the flow rate. The phase-change material will become solid at its melting point, and reheating requires a phase change process. Current circulating ink supply modules cannot support wax printing and present problems such as high cost, large space, complex connecting pipes, and low temperature uniformity. Summary of the Invention

[0004] The purpose of this application is to provide a circulating ink supply system and control method for 3D inkjet printing, particularly suitable for high-flow printing of high-temperature phase-change or high-viscosity printing materials. The integrated 3D inkjet printing circulating ink supply device within the circulating ink supply system offers advantages such as low cost, a more compact structure, ease of maintenance, and excellent temperature uniformity, making it particularly suitable for high-flow printing of high-temperature phase-change or high-viscosity printing materials.

[0005] In order to achieve the above objectives, this application adopts the following technical solutions:

[0006] The purpose of this application is to provide a circulating ink supply system suitable for 3D inkjet printing and a control method thereof, which is particularly suitable for high-flow printing of high-temperature phase change or high-viscosity printing materials.

[0007] In order to achieve the above objectives, this application adopts the following technical solutions:

[0008] In a first aspect, a circulating ink supply system suitable for 3D inkjet printing is provided, comprising:

[0009] An inkjet print head having a plurality of nozzles for ejecting ink; the ink is a high-temperature phase-change ink or a high-viscosity ink;

[0010] The circulation module is provided with an ink return chamber and an ink inlet chamber, the ink return chamber and the ink inlet chamber are connected; the ink return chamber and the ink inlet chamber are connected to the inkjet print head through an ink return pipe and an ink inlet pipe respectively;

[0011] A heating element, wherein the heating element is used to heat the circulation module;

[0012] The power module is used to provide kinetic energy to the circulating ink supply system, so that the ink circulates between the circulation module and the inkjet print head.

[0013] The circulation module is heated by the heating element, so that the high-temperature phase change ink or high-viscosity ink has better fluidity. The power module provides circulation kinetic energy, and the ink in the ink inlet chamber enters the inkjet print head through the ink inlet tube and flows to the ink return chamber through the ink return tube. The ink in the ink return chamber is transported to the connected ink inlet chamber, realizing the circulation of the fluid.

[0014] In a second aspect, the present application further provides a control method for a circulating ink supply system suitable for 3D inkjet printing. The circulating ink supply system is as described above, and the control method comprises the following steps:

[0015] (1) When the inkjet print head is in the printing state, the power module provides kinetic energy for the ink circulation;

[0016] (2) The ink in the ink inlet chamber enters the inkjet print head through the ink inlet tube and then flows from the ink return tube to the ink return chamber;

[0017] (3) When the ink in the ink return chamber reaches a certain height, the ink enters the ink inlet chamber connected to the ink return chamber, realizing the circulation of ink in the inkjet print head and the circulating ink supply structure.

[0018] Another control method for a circulating ink supply system suitable for 3D inkjet printing, the circulating ink supply system is as described above, and the control method includes the following steps:

[0019] (1) When the inkjet print head is in the printing state, the air pressure control module controls the pressure of the ink inlet chamber to make it greater than the pressure of the ink return chamber. The pressure of the ink inlet chamber is positive or negative;

[0020] (2) The ink in the ink inlet chamber enters the inkjet print head through the ink inlet tube and then flows from the ink return tube to the ink return chamber;

[0021] (3) The reflux pump is turned on, and the ink in the ink return chamber passes through the reflux valve, reflux pump, and filter to the buffer chamber in turn. When the ink in the buffer chamber reaches a certain height, the ink flows from the buffer chamber through the connecting hole to the ink inlet chamber, realizing the circulation of ink in the inkjet print head and the circulation module.

[0022] Another control method for a circulating ink supply system suitable for 3D inkjet printing, the circulating ink supply system is as described above, and the control method includes the following steps:

[0023] (1) When the inkjet print head is in the printing state, the air pressure control module controls the pressure between the ink inlet chamber and the ink return chamber, so that the pressure of the ink inlet chamber is greater than the pressure of the ink return chamber. The pressure of the ink inlet chamber is positive or negative, and the pressure of the ink return chamber is controlled to be negative;

[0024] (2) The ink in the ink inlet chamber enters the nozzle through the ink inlet tube and then flows from the ink return tube to the ink return chamber;

[0025] (3) When the ink in the ink return chamber reaches a certain height, the ink flows from the ink return chamber through the connecting hole to the ink return buffer chamber. The ink return level sensor in the ink return chamber is triggered when it detects ink when the ink return chamber liquid level reaches the set height. The reflux pump is turned on, and the ink in the ink return buffer chamber passes through the reflux valve, reflux pump, and filter in turn and flows to the ink inlet buffer chamber. When the ink in the ink inlet buffer chamber reaches a certain height, the ink flows from the ink inlet buffer chamber to the ink inlet chamber, realizing the circulation of ink in the inkjet print head and the circulation module.

[0026] In a third aspect, the present application further provides an integrated inkjet printing circulating ink supply device, comprising:

[0027] The heating chamber is provided with an ink return chamber, an ink return buffer chamber, an ink inlet buffer chamber and an ink inlet chamber. The ink inlet chamber and the ink inlet buffer chamber are adjacently arranged and communicated with each other through a first channel in the heating chamber. The ink return chamber and the ink return buffer chamber are adjacently arranged and communicated with each other through a communicating hole.

[0028] A heating element is provided on the periphery of the heating cavity for heating the heating cavity;

[0029] A reflux device, at least partially embedded in the heating chamber, communicating with the ink return buffer chamber and the ink inlet buffer chamber via an internal channel located in the heating chamber;

[0030] The ink inlet tube and the ink return tube are connected. The ink inlet tube connects the ink inlet cavity and the inkjet print head, and the ink return tube connects the ink return cavity and the inkjet print head.

[0031] Another integrated 3D inkjet printing circulating ink supply device includes:

[0032] The heating chamber is provided with an ink return chamber, a buffer chamber and an ink inlet chamber. The buffer chamber is located between the ink return chamber and the ink inlet chamber. The ink inlet chamber and the buffer chamber are connected through a connecting hole in the heating chamber.

[0033] A heating element is provided on the periphery of the heating cavity for heating the heating cavity;

[0034] A reflux device, at least partially embedded in the heating chamber, and connected to the ink return chamber and the buffer chamber through an internal channel located in the heating chamber;

[0035] The ink inlet tube and the ink return tube are connected. The ink inlet tube connects the ink inlet cavity and the inkjet print head, and the ink return tube connects the ink return cavity and the inkjet print head.

[0036] Due to the adoption of the above technical solution, this application has the following beneficial effects:

[0037] 1. The heating component heats the entire circulation module, keeping the ink fluid and preventing it from cooling and solidifying or becoming immobile due to high viscosity. This is particularly suitable for high-temperature phase change inks or high-viscosity inks (e.g., inks with viscosities between 1-200 cP). The power module circulates the ink within the inkjet printhead and circulation module, ensuring better temperature uniformity and removing bubbles and impurities from the printhead before filtering them out.

[0038] 2. By setting up a buffer chamber, the air pressure control module controls the pressure difference between the ink inlet chamber and the ink return chamber, allowing ink in the ink return chamber to flow through the buffer chamber to the ink inlet chamber. Ink in the ink inlet chamber enters the inkjet printhead through the ink inlet tube and flows through the ink return tube to the ink return chamber, achieving fluid circulation. The buffer chamber's first function is to eliminate bubbles mixed in the ink, a second function is to ensure smooth ink flow and eliminate flow pulses, and a third function is to ensure more uniform ink temperature. For low flow conditions, a buffer chamber is not required. For high flow conditions, the installation of a buffer chamber will make the system more stable.

[0039] 3. Under different working conditions, the flow rate of the fluid in the circulating ink supply system is different. The speed of the reflux pump in the reflux device controls the flow rate of the fluid, so that the circulating ink supply system can supply ink stably.

[0040] 4. For different working states of the inkjet print head, such as printing state, sleep state, ink pressing state, power-on state, etc., the ink supply system should have different methods to keep the ink supply system working stably.

[0041] 5. The circulation module features an integrated design. Except for the air pressure control module, ink inlet and outlet tubes, all other components and modules are housed within a heating chamber. Fluid flow is channeled through the chamber's internal flow channels. The chamber utilizes a uniform thermally conductive material, ensuring uniform temperature throughout the circulation system through heat conduction, keeping the high-temperature phase change material molten and enabling high-flow printing. This integrated design results in a more compact, low-cost, and easy-to-maintain structure. The simpler, more centralized heating design ensures uniform fluid temperature.

[0042] 6. Two-stage temperature control is implemented, with temperature sensors installed inside the ink inlet chamber and on the sidewall of the ink return chamber, to ensure uniform heating of the fluid and prevent deterioration of the fluid due to overheating during initial heating. The temperature sensor inside the ink inlet chamber directly measures the fluid temperature and provides direct feedback on the temperature of the fluid entering the printhead. Before the initial heating cycle is initiated, especially for phase-change fluids, the internal temperature of the fluid is relatively low. Therefore, a temperature sensor installed on the sidewall of the ink return chamber prevents the heating chamber from heating to excessively high temperatures, which could damage the fluid and affect printing.

[0043] 7. This circulating ink supply system supports high-flow, high-viscosity systems. High-temperature phase-change materials, such as wax, have high viscosity at certain temperatures. The heating component heats the entire circulation module to keep the ink flowing, preventing it from cooling and solidifying or becoming immobilized due to high viscosity. This system is particularly suitable for high-temperature phase-change inks or high-viscosity inks (e.g., inks with viscosities between 1 and 200 cP). The power of the entire system's circulation is determined by the pressure differential; increasing the pressure differential can increase the flow rate. Furthermore, electronic components and pumps are designed to support high-viscosity fluids. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The present application will be further described below with reference to the accompanying drawings.

[0045] FIG1 is a schematic diagram of the circulating ink supply system in Example 1.

[0046] FIG2 is a schematic structural diagram of an integrated inkjet printing circulating ink supply device from one angle.

[0047] FIG3 is a schematic structural diagram of the integrated inkjet printing circulating ink supply device from another angle.

[0048] Figure 4 is a schematic structural diagram of an ink cartridge;

[0049] FIG5 is a schematic diagram of the structure of the ink cartridge and the cover plate; wherein, the cover plate is simply indicated by dotted lines as part of the internal flow channel;

[0050] FIG6 is a right side view of the integrated inkjet printing circulating ink supply device;

[0051] FIG7 is a cross-sectional view taken along the GG plane of FIG6;

[0052] FIG8 is a cross-sectional view taken along the DD plane of FIG6;

[0053] FIG9 is a cross-sectional view taken along the FF plane of FIG6 ;

[0054] FIG10 is a schematic diagram of an inkjet print head and a circulation structure in a circulating ink supply system in Example 2;

[0055] Figure 11 is a schematic diagram of the circulating ink supply system of Example 3. DETAILED DESCRIPTION

[0056] Example 1

[0057] As shown in Figure 1, a circulating ink supply system suitable for 3D inkjet printing comprises an inkjet printhead 1, a circulation module 2, and an air pressure control module 3. The ink flow is indicated by arrows in Figure 1. The inkjet printhead 1 has multiple nozzles for ejecting ink. The ink can be a phase change wax, adhesive, flux, fine agent, photosensitive resin, or other fluid. It is particularly suitable for high-viscosity, high-flow, high-temperature phase change wax systems. Waxes typically have a melting point of 60-90°C. This inkjet printing circulating ink supply system can support heating temperatures of 60-150°C, materials with viscosities of 1-200 cP, and a flow rate greater than 100 ml / min per inkjet printhead. The circulation module 2 is equipped with an ink return chamber 4, an ink inlet chamber 5, an ink return buffer chamber 6, and an ink inlet buffer chamber 7. The ink inlet chamber 5 is connected to the ink inlet port IN of the inkjet printhead 1 via an ink inlet tube 11, while the ink return chamber 4 is connected to the ink return port OUT of the inkjet printhead 1 via an ink return tube 10. The ink inlet chamber 5 is equipped with an ink inlet temperature sensor 8b and an ink level sensor 9b, respectively, for monitoring the temperature and level of the ink in the ink inlet chamber 5. The ink inlet temperature sensor 8b extends deep into the ink inlet chamber 5 to directly measure the material temperature. An ink return temperature sensor 8a is installed on the outer wall of the ink return chamber 4 to monitor the outer wall temperature and prevent overheating during initial heating. For phase-change fluids, the initial heating ink circulation has not yet begun, and the internal center temperature of the fluid is relatively low. Therefore, a temperature sensor mounted on the entire chamber is required to prevent the chamber from heating to a high temperature, potentially damaging the fluid adjacent to the cavity surface and affecting printing. An ink return level sensor 9a is installed in the ink return chamber 4 to monitor the liquid level. The circulation module 2 heats the ink return chamber 4, ink inlet chamber 5, ink return buffer chamber 6, and ink inlet buffer chamber 7 via a heating assembly (not shown in Figure 1, but labeled 52 in Figure 2). A connecting hole 12a is provided between the ink return chamber 4 and the ink return buffer chamber 6, connecting the two chambers. A connecting hole 12b is provided between the ink inlet chamber 5 and the ink inlet buffer chamber 7, and the connecting hole 12b connects the ink inlet chamber 5 and the ink inlet buffer chamber 7. The return ink buffer chamber 6 and the ink inlet buffer chamber 7 are connected via a reflux device. The reflux device includes a reflux valve 13, a reflux pump 14 and a filter 15a. The return ink buffer chamber 6 is connected to the reflux valve 13 via a pipeline or channel, the reflux valve 13 is connected to the reflux pump 14 via a pipeline or channel, the reflux pump 14 is connected to the filter 15a via a pipeline or channel, and the filter 15a is connected to the ink inlet buffer chamber 7. The reflux pump 14 drives the ink circulation, and the flow rate of the reflux ink is adjusted by adjusting the rotation speed of the reflux pump 14 to ensure a stable supply of fluid to the inkjet print head 1. The reflux valve 13 can be a one-way valve or a solenoid valve, so that the ink flows in one direction. The filter 15a can select a corresponding filter according to the material of the ink, so as to filter the ink flowing back to the ink inlet buffer chamber 7.

[0058] As shown in Figure 1, the air pressure control module 3 is connected to the ink inlet chamber 5 and the ink return chamber 4, and is used to control the pressure difference between the ink inlet chamber 5 and the ink return chamber 4, thereby converting it into kinetic energy for the circulating ink supply system, causing the ink to circulate between the circulation module 2 and the inkjet printhead 1. The air pressure control module 3 includes a first pressure control module and a second pressure control module. The first pressure control module is used to control the pressure of the ink return chamber 4, which is negative pressure, and the second pressure control module is used to control the pressure of the ink inlet chamber 5, which can be positive or negative pressure. The ink return buffer chamber 6 can also be connected to the first pressure control module, or it can be sealed and not connected to a separate pressure control module, or it can be connected to a third pressure control module, which is connected to the first pressure control module. The ink inlet buffer chamber 7 can also be connected to the second pressure control module, or it can be sealed and not connected to a separate pressure control module, or it can be connected to a fourth pressure control module, which is connected to the second pressure control module.

[0059] The principle of a feasible air pressure control module 3 is shown in Figure 1. It includes a first air pressure chamber 16, a second air pressure chamber 17, a first buffer air pressure chamber 18, and a second buffer air pressure chamber 19. The first air pressure chamber 16 is connected to the ink return chamber 4 via a first air pipe 20 and a first positive-negative pressure switching valve 21. The second air pressure chamber 17 is connected to the ink inlet chamber 5 via a second air pipe 22 and a second positive-negative pressure switching valve 23. The first buffer air pressure chamber 18 is connected to the ink return buffer chamber 6 via a third air pipe 24 and a third positive-negative pressure switching valve 25. The second buffer air pressure chamber 19 is connected to the ink inlet buffer chamber 7 via a fourth air pipe 26 and a fourth positive-negative pressure switching valve 27. The first and second air pressure chambers 16 and 17 are each connected to an air pressure sensor 28a and 28b. The first, second, third, and fourth positive-negative pressure switching valves 21, 23, 25, and 27 are all connected to a single positive pressure pump 37. The inlet of the positive pressure pump 37 is connected to a filter 38. Providing two buffer air pressure chambers can eliminate air pressure fluctuations and make the air pressure control system more stable.

[0060] The first air pressure chamber 16 is connected to a first air source valve 30 and a first pressure relief valve 29, respectively. The second air pressure chamber 17 is connected to a second air source valve 32 and a second pressure relief valve 31, respectively. The air source valves can increase pressure in the air pressure chambers, and the pressure relief valves can reduce pressure in the air pressure chambers. The first air pressure chamber 16 and the first buffer air pressure chamber 18 are connected by a first buffer connecting pipe 33, and the second air pressure chamber 17 and the second buffer air pressure chamber 19 are connected by a second buffer connecting pipe 34. The first pressure relief valve 29 and the second pressure relief valve 31 are each connected to a filter 15b and 15c. The first air source valve 30 and the second air source valve 32 are each connected to an air pump 35a and 35b. A balancing valve 36 is connected between the first air pressure chamber 16 and the second air pressure chamber 17. The balancing valve 36 is connected to a backup power supply 39, or the balancing valve 36 is a normally open solenoid valve connected to a pressure reduction module 39.

[0061] Based on the principle of a circulating ink supply system suitable for 3D inkjet printing shown in Figure 1, the present application also designs an integrated 3D inkjet printing circulating ink supply device, referring to Figures 2 to 9. The integrated inkjet printing circulating ink supply device includes a heating chamber, and the heating chamber includes an ink cartridge 40. The ink cartridge 40 is roughly rectangular, in which an L-shaped ink return chamber 4, an L-shaped ink inlet chamber 5, an ink return buffer chamber 6 and an ink inlet buffer chamber 7 are provided. In order to achieve a compact structure, as shown in Figure 4, the ink return buffer chamber 6 is a slightly smaller rectangular structure located in the semi-enclosed structure of the L-shaped ink return chamber 4, and the ink inlet buffer chamber 7 is a slightly smaller rectangular structure located in the semi-enclosed structure of the L-shaped ink inlet chamber 5. The short sides of the L-shaped ink inlet chamber 5 and the L-shaped ink return chamber 4 are relatively parallel and located in the middle of the rectangular parallelepiped, and the long sides are located on both sides of the rectangular parallelepiped and extend in opposite directions. A connecting hole 12a is provided in the wall separating the ink return chamber 4 from the ink return buffer chamber 6. A first channel 41 (equivalent to connecting hole 12b) is provided in the ink cartridge 40 at the bottom of the ink inlet buffer chamber 7. The other end of first channel 41 connects to the ink inlet chamber 5. Both connecting hole 12a and first channel 41 are implemented by providing channels within the ink cartridge 40, rather than through external piping, which saves space and reduces additional heating. An ink inlet temperature sensor 8b and an ink level sensor 9b are provided within the ink inlet chamber 5. An ink return level sensor 9a is provided within the ink return chamber 4. An ink return temperature sensor 8a is provided on the outer wall of the ink return chamber 4 to monitor the outer wall temperature of the ink cartridge 40. As shown in Figure 9, the ink cartridge 40 below the ink inlet buffer chamber 7 has a mounting hole, within which a filter 15a is located. A second channel 42 is also provided within the ink cartridge 40, connecting the filter 15a with the ink inlet buffer chamber 7.

[0062] In conjunction with Figures 2-9 , the heating chamber further includes a cover plate 43, to which the ink cartridge 40 is sealed and fixedly connected. The cover plate 43 is generally L-shaped, with a reflux valve 13 embedded in one end of the cover plate 43 away from the ink inlet buffer chamber 7. The cover plate 43 has a reflux pump mounting portion 58, to which the reflux pump 14 is laterally fixed. The reflux pump 14 is arranged parallel to the length of the L-shaped cover plate 43. The reflux valve 13 is embedded in the cover plate 43 and disposed near the reflux pump mounting portion 58. The reflux pump 14 has an inlet 141 and an outlet 142. The cover plate 43 is provided with a third channel 44, which connects the inlet 141 of the reflux pump 14 with the outlet of the reflux valve 13. The cover plate 43, in conjunction with the ink cartridge 40, also features a fourth channel 56, connecting the reflux pump outlet 142 with the inlet of the filter 15a. This channel 56 is partially located within the ink cartridge 40 and partially within the cover plate 43. Since the reflux pump outlet 142 and the inlet of the filter 15a are located at opposite ends of the entire device, the fourth channel 56 spans the cover plate 43. The reflux valve 13 is located at the upper end of the ink return buffer chamber 6. The cover plate 43, in conjunction with the ink cartridge 40, also features a fifth channel 45, partially located within the ink cartridge 40 and partially within the cover plate 43. This fifth channel 45 connects the reflux valve 13 to the bottom of the ink return buffer chamber 6. Positioning the reflux valve 13 at the upper end of the ink return buffer chamber 6 reduces the length of the fifth channel 45. As shown in Figures 2, 3 and 5, both side walls of the ink cartridge 40 and the cover plate 43 extending in the longitudinal direction are provided with heating elements 52. The heating elements 52 are used to heat the entire ink cartridge 40 and the interior of the cover plate 43. A heat insulation plate can be provided on the outside of the heating element 52. The ink cartridge 40 is also provided with an ink inlet 55, which is connected to the ink return chamber 4 and is used to inject ink into the entire circulating ink supply system. The ink inlet chamber 5 and the ink return chamber 4 are connected to the inkjet print head 1 via the ink inlet tube 11 and the ink return tube 10. The outside of the ink inlet tube 11 and the ink return tube 10 are wrapped together with a heat conducting block 51. The heat conducting block 51 is in contact with the ink cartridge 40. Heat is conducted from the ink cartridge 40 to the heat conducting block 51 and then to the ink inlet tube 11 and the ink return tube 10 wrapped therein, thereby reducing the need for additional heating components and improving heat utilization. The ink return buffer chamber 6 and the ink inlet buffer chamber 7 do not need to occupy too much volume. The ink return buffer chamber 6 and the ink inlet buffer chamber 7 are designed to be located in the L-shaped semi-enclosed structure of the ink return chamber 4 and the ink inlet chamber 5, respectively. This is conducive to compact space while ensuring the volume requirements of the ink inlet chamber 5 and the ink return chamber 4. The reflux pump 14 is relatively long, and the reflux pump 14 is arranged parallel to the length direction of the L-shaped cover plate 43 to make the space compact. The reflux valve 13 is embedded in the cover plate 43 and connected to the reflux pump 14 and the ink return buffer chamber 6 through an internal channel, and then the heating chamber is heated by the heating element 52, which can reduce the additional heating of the external pipeline and improve space utilization and energy utilization.

[0063] As shown in Figures 2, 3, and 5, the cover plate 43 further comprises a first air interface 46a, a second air interface 46b, a third air interface 46c, and a fourth air interface 46d. A sixth channel 47, a seventh channel 48, an eighth channel 49, and a ninth channel 50 are provided within the cover plate 43. The sixth channel 47 connects the first air interface 46a with the ink return chamber 4, and the seventh channel 48 connects the third air interface 46c with the ink return buffer chamber 6. The first and third air interfaces 46a, 46c are located near the ink return chamber 4 and the ink return buffer chamber 6. The eighth channel 49 connects the second air interface 46b with the ink inlet chamber 5, and the ninth channel 50 connects the fourth air interface 46d with the ink inlet buffer chamber 7. The second and fourth air interfaces 46b, 46d are located on the side opposite the first and third air interfaces 46a, 46c.

[0064] The first air path interface 46a, the second air path interface 46b, the third air path interface 46c, and the fourth air path interface 46d are respectively connected to the first air pipe 20, the second air pipe 22, the third air pipe 24, and the fourth air pipe 26 of the air pressure control module 3. The specific composition of the air pressure control module 3 is shown in Figure 1 and will not be described here.

[0065] The integrated 3D inkjet printing circulating ink supply device is rationally arranged. Except for the air pressure control module 3, ink inlet tube 11, and ink return tube 10, all other components and modules are placed within the heated ink cartridge 40 and cover plate 43. The fluid channel is realized through the internal flow channels of the ink cartridge 40 and cover plate 43. The ink cartridge 40 and cover plate 43 use a uniform thermal conductive material. Through heat conduction, the temperature of the entire circulation system is uniform, ensuring that the wax material remains in a molten state, thereby achieving high-flow printing. The integrated structural design rationally utilizes internal space, facilitates space saving and facilitates miniaturization of the device, and improves heat utilization.

[0066] When the inkjet print head 1 is in the printing state, the circulating ink supply system is controlled as follows:

[0067] (1) The first air pressure chamber 16 provides pressure to the ink return chamber 4 through the first air pipe 20 so that it maintains the printing pressure P1, the second air pressure chamber 17 provides pressure to the ink inlet chamber 5 through the second air pipe 22 so that it maintains the printing pressure P2, the first buffer air pressure chamber 18 provides printing pressure P1 to the ink return buffer chamber 6 through the third air pipe 24, and the second buffer air pressure chamber 19 provides printing pressure P2 to the ink inlet buffer chamber 7 through the fourth air pipe 26, wherein P1 is a negative pressure, and there is a pressure difference between P1 and P2; the printing pressure P2 provided to the ink inlet buffer chamber 7 is greater than the printing pressure P1 provided to the ink return buffer chamber 6; P1 is a large negative pressure, and P2 is a small negative pressure or a positive pressure.

[0068] (2) The fluid (i.e., ink) in the ink inlet chamber 5 enters the inkjet print head 1 through the ink inlet tube 11 and then flows from the ink return tube 10 to the ink return chamber 4;

[0069] (3) When the fluid in the ink return chamber 4 reaches a certain height, the fluid flows from the ink return chamber 4 through the connecting hole 12a to the ink return buffer chamber 6. The ink return level sensor 9a in the ink return chamber 4 is triggered when the liquid level in the ink return chamber 4 reaches the set height, and the reflux pump 14 is turned on. The fluid in the ink return buffer chamber 6 passes through the reflux valve 13, the reflux pump 14, and the filter 15a in turn and flows to the ink inlet buffer chamber 7. When the fluid in the ink inlet buffer chamber 7 reaches a certain height, the fluid flows from the ink inlet buffer chamber 7 to the ink inlet chamber 5, realizing the circulation of the fluid in the inkjet print head 1 and the circulation module 2. The operation of the reflux pump 14 is algorithmically controlled according to the value of the liquid level sensor or the time parameter to match the corresponding material circulation speed. The circulation of the fluid in the inkjet print head 1 and the circulation module 2 can ensure better temperature uniformity of the fluid; it can support some nozzles that do not have a heating module; the circulation can take away bubbles and impurities in the nozzle and filter them out; the circulation can support the printing of some special fluids (such as those that will precipitate and have high viscosity).

[0070] In order to maintain the nozzle state of the inkjet print head 1 and ensure that the nozzles are clean, it is necessary to press the ink. When the inkjet print head 1 is in the ink pressing state, the circulating ink supply system undergoes the following control:

[0071] (1) The pressure sensor adjusts the working speed of the positive pressure pump 37 so that the positive pressure pump 37 maintains a certain pressure;

[0072] (2) The first positive-negative pressure switching valve 21, the second positive-negative pressure switching valve 23, the third positive-negative pressure switching valve 25 and the fourth positive-negative pressure switching valve 27 are all switched and connected to the positive pressure pump 37 (originally, the positive-negative pressure switching valves were all connected to the corresponding air pressure chambers above). The positive pressure pump 37 applies positive pressure to the first air pipe 20, the second air pipe 22, the third air pipe 24 and the fourth air pipe 26 to pressurize ink to the inkjet print head 1.

[0073] When the inkjet print head 1 is in a dormant state, the temperature in the heating chamber is lowered, but is higher than the freezing point of the wax material to prevent it from solidifying. The circulating ink supply system is controlled as follows: the dormant pressure P1' of the first air pipe 20 and the dormant pressure P2' of the second air pipe 22 are adjusted to be consistent.

[0074] P1' = P2' = (P1 + P2) / 2 - P0, where P0 is the corrected pressure from the dynamic to static state of the fluid; P1 is the printing pressure of the ink return chamber 4 during printing, and P2 is the printing pressure of the ink inlet chamber 5 during printing. Pressure adjustment during sleep mode prevents or slows ink circulation, preserving component life.

[0075] When the inkjet print head 1 is powered on, the ink circulation system of the inkjet print head 1 is controlled as follows: When the inkjet print head 1 is powered on, the fluid temperature T1 in the ink cartridge 40 and the temperature T2 of the inkjet print head 1 are detected. If T1>T0, T2>T0, and T0 is the liquid temperature of the fluid, the relevant protection is released (for example, the contact protection of the reflux pump 14 can be turned on and the negative pressure can take effect), and the air pressure of the first air pipe 20 and the second air pipe 22 are slowly adjusted to the printing pressure P1 and the printing pressure P2 respectively. Perform fluid circulation; if T1 or T2 ≤ T0, it means that the fluid has become solid, keep the reflux pump 14 closed, the air pressure of the first air pipe 20 and the second air pipe 22 are both 0, first heat the fluid to the set temperature Ta through the heating component to keep the fluid in liquid state, and after confirming that the fluid is liquid, adjust the air pressure of the first air pipe 20 and the second air pipe 22 to the printing pressure P1 and the printing pressure P2 respectively; here the heating time can be calculated by first calculating the temperature difference △T1=T1-T0 between the fluid temperature T1 and T0 of the ink cartridge 40, and the temperature difference △T2=T2-T0 between the temperature T2 and T0 of the inkjet print head 1, and dynamically derive the heating time required for the ink cartridge 40 and the inkjet print head 1 according to the solid-liquid heating curve of the fluid, the heating and heat transfer design of the ink cartridge 40 and the inkjet print head 1, and the relevant empirical parameters.

[0076] When the inkjet print head 1 is in a power-off state, the circulating ink supply system is controlled as follows: the reflux pump 14 is closed, the balancing valve 36 is opened, the first air pressure chamber 16 and the second air pressure chamber 17 are connected through the balancing valve 36, and finally the pressure difference between the first air pressure chamber 16 and the second air pressure chamber 17 is made 0. The first buffer air pressure chamber 18 is connected to the first air pressure chamber 16 through the first buffer tube 33, so the pressure of the first buffer air pressure chamber 18 is equal to that of the first air pressure chamber 16. Similarly, the pressure of the second buffer air pressure chamber 19 is equal to that of the second air pressure chamber 17. The pressure differences of the first air pressure chamber 16, the second air pressure chamber 17, the first buffer air pressure chamber 18, and the second buffer air pressure chamber 19 are all 0. In a conventional system, if the system suddenly loses power, the first air pressure chamber 16, the second air pressure chamber 17, the first buffer air pressure chamber 18, and the second buffer air pressure chamber 19 will maintain the current pressure, so the fluid in the ink cartridge 40 will still circulate, but the reflux pump 14 will not work. After a certain period of time, the first air pipe 20 and the third air pipe 24 will suck in the fluid, and the pre-cooling and solidification of the fluid will destroy the circulating ink supply system. Therefore, this circulating ink supply system sets a balancing valve 36 to make the pressure difference 0 to stop the circulation and perform power-off protection. The inkjet print head 1 also maintains an appropriate negative pressure to prevent leakage, thereby preventing waste of wax materials.

[0077] Example 2

[0078] Similar to the circulating ink supply system in Example 1, the circulating ink supply system in this embodiment also includes an inkjet print head 1, a circulation module 2, and an air pressure control module 3. The difference is that the circulation module 2 in this embodiment has only one buffer chamber. The inkjet print head 1 and circulation module 2 in Example 2 are shown in Figure 10.

[0079] The circulation module 2 includes an ink inlet chamber 5, an ink return chamber 4, and a buffer chamber 53. The ink inlet chamber 5 is connected to a first air pipe 20 for regulating negative pressure. The first air pipe 20 is connected to an air pressure control module 3. The air pressure control module 3 can be the same as or different from that in Figure 1, as long as any module capable of achieving air pressure control and regulation functions is acceptable. The ink return chamber 4 and the buffer chamber 53 are connected by a reflux device. A connecting hole 12 is provided between the buffer chamber 53 and the ink inlet chamber 5. The ink return chamber 4 and the ink return tube 10 are respectively connected to pressure sensors 54a and 54b. These two pressure sensors can respectively measure the air pressure above the ink return chamber 4 and the fluid pressure within the ink return tube 10. The ink inlet chamber 5 is equipped with an ink inlet temperature sensor 8b and an ink inlet level sensor 9b. The flow of fluid is shown by the arrows in Figure 10. The reflux device includes a reflux valve 13, a reflux pump 14, and a filter 15a, which are connected in sequence via pipes or channels. The outlet of the filter 15a is connected to the buffer chamber 53, and the inlet of the reflux valve 13 is connected to the ink return chamber 4. Another filter 15 d may be provided in the ink inlet tube 11 (or may not be provided).

[0080] When the inkjet print head 1 is in the printing state, the circulating ink supply system is controlled as follows:

[0081] (1) The air pressure control module 3 controls the pressure of the ink inlet chamber 5 through the first air pipe 20 so that it is greater than the pressure of the ink return chamber 4. The pressure of the ink inlet chamber 5 is positive or negative. (2) The fluid in the ink inlet chamber 5 enters the inkjet print head 1 through the ink inlet tube 11 and then flows from the ink return tube 10 to the ink return chamber 4.

[0082] (3) The reflux pump 14 is turned on, and the fluid in the ink return chamber 4 passes through the reflux valve 13, the reflux pump 14, and the filter 15a in sequence to the buffer chamber 53. When the fluid in the buffer chamber 53 reaches a certain height, the fluid flows from the buffer chamber 53 through the connecting hole 12 to the ink inlet chamber 5, thereby realizing the circulation of the fluid in the inkjet print head 1 and the circulation module 2;

[0083] (4) Monitor the values ​​of pressure sensors 54a and 54b, and adjust the speed of the return pump 14 to match the corresponding material circulation speed based on the integrated algorithm of the pressure sensors 54a and 54b, the connected system negative pressure, and the speed of the return pump 14, so as to adjust the system negative pressure to achieve the appropriate meniscus pressure. The meniscus pressure is the fluid pressure required by the inkjet print head 1. The actual parameters of different types of print heads are different. When printing, the pressure parameters are adjusted according to the actual printing effect based on whether the nozzle can maintain the fluid without dripping and the printing effect. The system negative pressure here refers to the pressure difference of the entire system, that is, the difference between the pressure of the ink return chamber 4 and the pressure of the ink inlet chamber 5. The difference is a negative value.

[0084] According to Figures 2 to 9 of Example 1, an integrated 3D inkjet printing circulating ink supply device is provided. This embodiment also provides an integrated 3D inkjet printing circulating ink supply device, whose structure is generally similar to the structure shown in Figures 2 to 9, including: a heating chamber, the heating chamber is provided with an ink return chamber 4, a buffer chamber 53 and an ink inlet chamber 5, the buffer chamber 53 is located between the ink return chamber 4 and the ink inlet chamber 5, and the ink inlet chamber 5 and the buffer chamber 53 are connected through a connecting hole 12 in the heating chamber; a heating element, the heating element is arranged on the periphery of the heating chamber for heating the heating chamber; a reflux device, the reflux device is at least partially embedded in the heating chamber, and the reflux device is connected to the ink return chamber 4 and the buffer chamber 53 through an internal channel located in the heating chamber; an ink inlet tube 11 and an ink return tube 10, the ink inlet tube 11 connects the ink inlet 5 chamber and the inkjet print head 1, and the ink return tube 10 connects the ink return chamber 4 and the inkjet print head 1. The reflux valve 13 is disposed above the ink return chamber 4 and communicates with the bottom of the ink return chamber 4 via an internal passage. The reflux pump 14 is fixed to the upper portion of the heating chamber, with the inlet of the reflux pump 14 communicating with the outlet of the reflux valve 13 via an internal passage. The filter 15a is disposed adjacent to the buffer chamber 53, with the outlet of the reflux pump 14 communicating with the filter 15a via an internal passage. The outlet of the filter 15a also communicates with the buffer chamber 53 via an internal passage. The filter 15a is embedded within the ink cartridge 40 and connects the reflux pump 14 to the ink inlet buffer chamber 7 via an internal passage. The heating chamber is then heated by the heating element 52, thereby reducing the need for additional heating of external piping and improving space and energy utilization.

[0085] Example 3

[0086] As shown in Figure 11, the circulating ink supply system includes an inkjet print head 1, a circulation module 2, and a circulation pump 57. The circulation module 2 includes an ink inlet chamber 5 and an ink return chamber 4. The ink inlet chamber 5 and the ink return chamber 4 are connected or integrated. The circulation pump 57 is arranged on the ink inlet tube 11 and provides the power required for the circulating ink supply system. The inlet of the circulation pump 57 is connected to the ink inlet chamber 5 via the ink inlet tube 11. The filter 15e is connected to the outlet of the circulation pump 57. The outlet of the filter 15e is connected to the ink inlet IN of the inkjet print head 1. The ink return OUT of the inkjet print head 1 is connected to the ink return chamber 4 via the ink return tube 10. The ink return tube 10 is equipped with a reflux valve 13, which can be a one-way valve or a solenoid valve. The ink inlet chamber 5 is connected to the first air pipe 20, which functions to regulate negative pressure. The first air pipe 20 is connected to the air pressure control module. The ink inlet tube 11 is equipped with a pressure sensor 54c.

[0087] When the inkjet print head 1 is in the printing state, the circulating ink supply system is controlled as follows:

[0088] (1) The first air pipe 20 provides negative pressure to the inkjet print head 1;

[0089] (2) The circulation pump 57 is turned on. The fluid in the ink inlet chamber 5 enters the inkjet print head 1 through the ink inlet tube 11 and then flows from the ink return tube 10 to the ink return chamber 4. The ink inlet chamber 5 and the ink return chamber 4 are connected. The ink flows back to the ink inlet chamber 5, realizing the circulation of the fluid in the inkjet print head 1 and the circulation module 2.

[0090] (3) Monitor the value of pressure sensor 54c, and adjust the speed of circulation pump 57 to match the corresponding material circulation speed based on the integrated algorithm of pressure sensor 54c, the connected system negative pressure, and the speed of circulation pump 57, thereby adjusting the system negative pressure to achieve the appropriate meniscus pressure. The system negative pressure here refers to the negative pressure provided by the first air pipe 20 to the inkjet print head 1.

[0091] The above are only specific embodiments of the present application, but the technical features of the present application are not limited thereto. Any simple changes, equivalent replacements, or modifications based on the present application to solve substantially the same technical problems and achieve substantially the same technical effects are all included in the scope of protection of the present application.

Claims

1. A circulating ink supply system suitable for 3D inkjet printing, characterized in that include: An inkjet print head, wherein the inkjet print head has a plurality of nozzles for ejecting ink; the ink is a high-temperature phase change ink or a high-viscosity ink; A circulation module, wherein the circulation module is provided with an ink return chamber and an ink inlet chamber, wherein the ink return chamber and the ink inlet chamber are in communication with each other; the ink return chamber and the ink inlet chamber are connected to the inkjet print head through an ink return pipe and an ink inlet pipe respectively; A heating element, the heating element is used to heat the circulation module; A power module is used to provide kinetic energy for the circulating ink supply system so that the ink circulates between the circulation module and the inkjet print head.

2. A circulating ink supply system suitable for 3D inkjet printing as claimed in claim 1, characterized in that: The power module is a circulation pump, which is arranged on the ink inlet pipe and is used to transport the ink from the ink inlet cavity to the inkjet print head.

3. A circulating ink supply system suitable for 3D inkjet printing as claimed in claim 1, characterized in that: The power module is an air pressure control module, which is connected to the ink inlet chamber or the ink return chamber and is used to control the pressure difference between the ink inlet chamber and the ink return chamber to convert it into kinetic energy of the circulating ink supply system.

4. A circulating ink supply system suitable for 3D inkjet printing as claimed in claim 2 or 3, characterized in that: The circulation module also includes a buffer chamber, which is connected to the ink return chamber and the ink inlet chamber; the heating element heats the ink return chamber, the ink inlet chamber, the buffer chamber, and a pipe or channel connecting the buffer chamber with the ink return chamber and the ink inlet chamber.

5. A circulating ink supply system suitable for 3D inkjet printing as claimed in any one of claims 1 to 4, characterized in that: The heating element can heat the circulation module to 60-150°C; an ink inlet temperature sensor and an ink inlet level sensor are provided in the ink inlet cavity for monitoring the ink temperature and level in the ink inlet cavity; an ink return level sensor is provided in the ink return cavity for monitoring the ink level in the ink return cavity; an ink return temperature sensor is provided on the side wall of the ink return cavity for monitoring the temperature of the side wall.

6. A circulating ink supply system suitable for 3D inkjet printing as claimed in claim 4, characterized in that: The buffer chamber is connected to the ink inlet chamber through a connecting hole, and the ink return chamber is connected to the buffer chamber through a reflux device; the circulating ink supply system controls the pressure of the ink inlet chamber / ink return chamber through an air pressure control module so that the ink enters the buffer chamber from the ink return chamber through the connecting hole, enters the ink inlet chamber through the reflux device, and then enters the inkjet print head through the ink inlet tube and returns to the ink return chamber through the ink return tube, forming a cycle.

7. A circulating ink supply system suitable for 3D inkjet printing as claimed in claim 6, characterized in that: The reflux device comprises a reflux valve, a reflux pump and a filter which are connected in sequence. The inlet of the reflux valve is connected to the ink return chamber, and the outlet of the filter is connected to the buffer chamber.

8. A circulating ink supply system suitable for 3D inkjet printing as claimed in claim 4, characterized in that: The buffer chamber includes an ink return buffer chamber and an ink inlet buffer chamber, the ink return buffer chamber is connected to the ink return chamber via a connecting hole, the ink inlet buffer chamber is connected to the ink inlet chamber via another connecting hole, the ink return buffer chamber and the ink inlet buffer chamber are connected via a reflux device; the reflux device includes a reflux valve, a reflux pump, and a filter connected in sequence, the inlet of the reflux valve is connected to the ink return buffer chamber, and the outlet of the filter is connected to the ink inlet buffer chamber.

9. A circulating ink supply system suitable for 3D inkjet printing as claimed in claim 8, characterized in that: The power module is an air pressure control module, which includes a first pressure control module and a second pressure control module. The first pressure control module is connected to the ink return chamber for controlling the pressure of the ink return chamber, and the pressure of the ink return chamber is negative pressure. The second pressure control module is connected to the ink inlet chamber for controlling the pressure of the ink inlet chamber, and the pressure of the ink inlet chamber can be positive pressure or negative pressure. The circulating ink supply system uses the air pressure control module to allow the ink to enter the ink return buffer chamber from the ink return chamber through the connecting hole, and enter the ink inlet buffer chamber through the reflux device, and then enter the ink inlet chamber through the other connecting hole, and enter the ink jet print head through the ink inlet tube and then return to the ink return chamber through the ink return tube to form a cycle.

10. The circulating ink supply system suitable for 3D inkjet printing as claimed in claim 9, characterized in that: The air pressure control module includes a first air pressure chamber, a second air pressure chamber, a first buffer air pressure chamber and a second buffer air pressure chamber. The ink return chamber is connected to the first air pressure chamber through the first positive and negative pressure switching valve, the ink inlet chamber is connected to the second air pressure chamber through the second positive and negative pressure switching valve, the ink return buffer chamber is connected to the first buffer air pressure chamber through the third positive and negative pressure switching valve, and the ink inlet buffer chamber is connected to the second buffer air pressure chamber through the fourth positive and negative pressure switching valve. The first air pressure chamber and the second air pressure chamber are each connected to an air pressure sensor, and the first positive and negative pressure switching valve, the second positive and negative pressure switching valve, the third positive and negative pressure switching valve and the fourth positive and negative pressure switching valve are all connected to the same positive pressure pump.

11. The circulating ink supply system for 3D inkjet printing according to claim 9, characterized in that: The first air pressure chamber is connected to a first air source valve and a first pressure relief valve, the second air pressure chamber is connected to a second air source valve and a second pressure relief valve, the first air pressure chamber and the first buffer air pressure chamber are connected via a first buffer connecting pipe, and the second air pressure chamber and the second buffer air pressure chamber are connected via a second buffer connecting pipe; the first pressure relief valve and the second pressure relief valve are each connected to a filter, the first air source valve and the second air source valve are each connected to an air pump, and a balancing valve is connected between the first air pressure chamber and the second air pressure chamber.

12. A control method for a circulating ink supply system suitable for 3D inkjet printing, characterized in that: The circulating ink supply system is as described in any one of claims 1 to 3, and the control method comprises the following steps: (1) When the inkjet print head is in the printing state, the power module provides kinetic energy for ink circulation; (2) The ink in the ink inlet chamber enters the inkjet print head through the ink inlet tube and then flows from the ink return tube to the ink return chamber; (3) When the ink in the ink return chamber reaches a certain height, the ink enters the ink inlet chamber connected to the ink return chamber, thereby realizing the circulation of ink in the inkjet print head and the circulating ink supply structure.

13. A control method for a circulating ink supply system suitable for 3D inkjet printing, characterized in that: The circulating ink supply system is as described in claims 4-7, and the control method comprises the following steps: (1) When the inkjet print head is in the printing state, the air pressure control module controls the pressure of the ink inlet chamber to be greater than the pressure of the ink return chamber, and the pressure of the ink inlet chamber is positive pressure or negative pressure; (2) The ink in the ink inlet chamber enters the inkjet print head through the ink inlet tube and then flows from the ink return tube to the ink return chamber; (3) The reflux pump is turned on, and the ink in the ink return chamber passes through the reflux valve, reflux pump, filter and buffer chamber in turn. When the ink in the buffer chamber reaches a certain height, the ink flows from the buffer chamber through the connecting hole to the ink inlet chamber, thereby realizing the circulation of ink in the inkjet print head and circulation module.

14. The control method of the circulating ink supply system suitable for 3D inkjet printing according to claim 12, characterized in that: The control method further includes step (4), monitoring the value of the pressure sensor, such as the pressure sensor and the connected system negative pressure and the speed of the reflux pump, and adjusting the speed of the reflux pump by a comprehensive algorithm to match the corresponding material circulation speed, and adjusting the system negative pressure to achieve a suitable meniscus pressure.

15. A control method for a circulating ink supply system suitable for 3D inkjet printing, characterized in that: The circulating ink supply system is as described in claims 8-11, and the control method comprises the following steps: (1) When the inkjet print head is in the printing state, the air pressure control module controls the pressure between the ink inlet chamber and the ink return chamber, so that the pressure of the ink inlet chamber is greater than the pressure of the ink return chamber, the pressure of the ink inlet chamber is positive pressure or negative pressure, and the pressure of the ink return chamber is controlled to be negative pressure; (2) The ink in the ink inlet chamber enters the nozzle through the ink inlet tube and then flows from the ink return tube to the ink return chamber; (3) When the ink in the ink return chamber reaches a certain height, the ink flows from the ink return chamber through the connecting hole to the ink return buffer chamber. The ink return level sensor in the ink return chamber is triggered when it detects ink when the ink return chamber liquid level reaches the set height. The reflux pump is turned on, and the ink in the ink return buffer chamber is filtered through the reflux valve, reflux pump, and filter in turn and flows to the ink inlet buffer chamber. When the ink in the ink inlet buffer chamber reaches a certain height, the ink flows from the ink inlet buffer chamber to the ink inlet chamber, thereby realizing the circulation of ink in the inkjet print head and the circulation module.

16. The control method of the circulating ink supply system suitable for 3D inkjet printing according to claim 15, characterized in that: The specific operation of step (1) is as follows: the first air pressure chamber provides pressure to the ink return chamber through the first air pipe so that it maintains a printing pressure P1, the second air pressure chamber provides pressure to the ink inlet chamber through the second air pipe so that it maintains a printing pressure P2, the first buffer air pressure chamber provides printing pressure P1 to the ink return buffer chamber through the third air pipe, and the second buffer air pressure chamber provides printing pressure P2 to the ink inlet buffer chamber through the fourth air pipe, wherein P1 is a negative pressure and P2 is greater than P1.

17. The control method of the circulating ink supply system suitable for 3D inkjet printing according to claim 15, characterized in that When the inkjet print head is in the ink pressing state, the circulating ink supply system is controlled as follows: (1) The pressure sensor adjusts the working speed of the positive pressure pump to keep the positive pressure pump at a certain pressure; (2) The first positive-negative pressure switching valve, the second positive-negative pressure switching valve, the third positive-negative pressure switching valve and the fourth positive-negative pressure switching valve are all switched and connected to a positive pressure pump. The positive pressure pump applies positive pressure to the first air pipe, the second air pipe, the third air pipe and the fourth air pipe to pressurize ink to the inkjet print head.

18. The control method of the circulating ink supply system suitable for 3D inkjet printing according to claim 16, characterized in that: When the nozzle is in a dormant state, the temperature in the heating chamber is lowered, but higher than the solidification point of the high-temperature phase change material. The dormant pressure P1' of the first air pipe and the dormant pressure P2' of the second air pipe are adjusted to be consistent, P1'= P2'=(P1+P2) / 2-P0, where P0 is the corrected pressure of the ink from dynamic to static, P1 is the printing pressure of the ink return chamber in the printing state, and P2 is the printing pressure of the ink inlet chamber in the printing state.

19. The control method of the circulating ink supply system suitable for 3D inkjet printing according to claim 14, characterized in that: When the inkjet print head is in the power-on state, the ink temperature T1 in the ink cartridge and the inkjet print head temperature T2 are detected. If T1≥T0, T2≥T0, and T0 is the liquid temperature of the ink, the relevant protection is released, and the air pressure of the first air pipe and the second air pipe are slowly adjusted to the printing pressure P1 and the printing pressure P2 respectively to circulate the ink; if T1 or T2≤T0, the reflux pump is kept closed, and the air pressure of the first air pipe and the second air pipe are both 0. The ink is first heated to the set temperature Ta by the heating component to keep the ink in liquid state. After confirming that the ink is liquid, the air pressure of the first air pipe and the second air pipe are adjusted to the printing pressure P1 and the printing pressure P2 respectively.

20. The control method of the circulating ink supply system suitable for 3D inkjet printing according to claim 14, characterized in that: When the nozzle is in a power-off state, the reflux pump is closed, the balancing valve is opened, and the pressure differences of the first air pressure chamber, the second air pressure chamber, the first buffer air pressure chamber, and the second buffer air pressure chamber are all zero.

21. An integrated 3D inkjet printing circulating ink supply device, characterized in that include: A heating chamber, wherein the heating chamber is provided with an ink return chamber and an ink inlet chamber; A heating element, the heating element being arranged at the periphery of the heating cavity for heating the heating cavity; An ink inlet tube and an ink return tube, wherein the ink inlet tube connects the ink inlet cavity and the inkjet print head, and the ink return tube connects the ink return cavity and the inkjet print head.

22. An integrated 3D inkjet printing circulating ink supply device as claimed in claim 21, characterized in that: It also includes a reflux device, which is at least partially embedded in the heating chamber, and the heating chamber is provided with an ink return buffer chamber and an ink inlet buffer chamber, the ink inlet chamber is adjacent to the ink inlet buffer chamber and is connected through a first channel in the heating chamber, the ink return chamber is adjacent to the ink return buffer chamber and is connected through a connecting hole, and the reflux device connects the ink return buffer chamber with the ink inlet buffer chamber through an internal channel located in the heating chamber.

23. An integrated 3D inkjet printing circulating ink supply device as claimed in claim 22, characterized in that: The heating chamber includes an ink cartridge and a cover plate, the ink cartridge and the cover plate are sealed and fixed, the ink return chamber, ink return buffer chamber, ink inlet buffer chamber and ink inlet chamber are arranged in the ink cartridge, the ink return chamber and the ink inlet chamber are L-shaped, the ink return buffer chamber and the ink inlet buffer chamber are respectively located in the L-shaped semi-enclosed structure of the ink return chamber and the ink inlet chamber, and the short sides of the ink return chamber and the ink inlet chamber are adjacent to each other.

24. An integrated 3D inkjet printing circulating ink supply device as claimed in claim 23, characterized in that: The cover plate is L-shaped and has a reflux pump mounting portion. The reflux device includes a reflux pump, which is transversely fixed to the reflux pump mounting portion. The reflux pump is arranged parallel to the length direction of the L-shaped cover plate.

25. An integrated 3D inkjet printing circulating ink supply device as claimed in claim 23, characterized in that: The reflux device also includes a reflux valve, which is embedded in the cover plate and located at the upper end of the ink return buffer chamber; the cover plate is provided with a third channel, which connects the inlet of the reflux pump with the outlet of the reflux valve, and the cover plate and the ink cartridge are also provided with a fifth channel, which is partially located in the ink cartridge and partially located in the cover plate, and the fifth channel connects the reflux valve and the bottom of the ink return buffer chamber; the reflux device also includes a filter, which is embedded below the ink inlet buffer chamber, and the ink cartridge is also provided with a second channel, which connects the filter with the ink inlet buffer chamber; the cover plate and the ink cartridge are also provided with a fourth channel, which connects the outlet of the reflux pump with the inlet of the filter.

26. An integrated 3D inkjet printing circulating ink supply device as claimed in claim 21, characterized in that: The integrated inkjet printing circulating ink supply device also includes an air circuit interface, which is connected to the air pressure control module. The air circuit interface is arranged on the side wall of the cover plate, and the air circuit interface is connected to the ink inlet cavity or the ink return cavity through a channel inside the cover plate.

27. An integrated 3D inkjet printing circulating ink supply device as claimed in claim 26, characterized in that: The cover plate is provided with a first air circuit interface, a second air circuit interface, a third air circuit interface, and a fourth air circuit interface, and a sixth channel, a seventh channel, an eighth channel, and a ninth channel are provided inside the cover plate, the sixth channel is connected with the first air circuit interface and the ink return chamber, the seventh channel is connected with the third air circuit interface and the ink return buffer chamber, the first air circuit interface and the third air circuit interface are arranged on the side close to the ink return chamber and the ink return buffer chamber; the eighth channel is connected with the second air circuit interface and the ink inlet chamber, and the ninth channel is connected with the fourth air circuit interface and the ink inlet buffer chamber; the second air circuit interface and the fourth air circuit interface are arranged on the other side opposite to the first air circuit interface and the third air circuit interface; The first air circuit interface, the second air circuit interface, the third air circuit interface, and the fourth air circuit interface are respectively connected to the first air pipe, the second air pipe, the third air pipe, and the fourth air pipe of the air pressure control module.

28. An integrated 3D inkjet printing circulating ink supply device according to any one of claims 21 to 27, characterized in that: The outer sides of the ink inlet tube and the ink return tube are wrapped with a heat conductive block, and the heat conductive block is in contact with the ink cartridge for heat conduction; an ink inlet temperature sensor and an ink inlet level sensor are provided in the ink inlet cavity, an ink return level sensor is provided in the ink return cavity, and an ink return temperature sensor is provided on the outer wall of the ink return cavity for monitoring the temperature of the ink cartridge.

29. An integrated 3D inkjet printing circulating ink supply device, characterized in that include: A heating chamber, wherein the heating chamber is provided with an ink return chamber, a buffer chamber and an ink inlet chamber, wherein the buffer chamber is located between the ink return chamber and the ink inlet chamber, and the ink inlet chamber is connected to the buffer chamber through a connecting hole in the heating chamber; A heating element, the heating element being arranged at the periphery of the heating cavity for heating the heating cavity; A reflux device, wherein the reflux device is at least partially embedded in the heating chamber, and the reflux device is connected to the ink return chamber and the buffer chamber through an internal channel located in the heating chamber; An ink inlet tube and an ink return tube, wherein the ink inlet tube connects the ink inlet cavity and the inkjet print head, and the ink return tube connects the ink return cavity and the inkjet print head.

30. The integrated 3D inkjet printing circulating ink supply device according to claim 29, characterized in that: The reflux device includes a reflux valve, a reflux pump and a filter. The reflux valve is arranged above the ink return chamber, and the reflux valve is connected to the bottom of the ink return chamber through an internal channel. The reflux pump is fixed to the upper part of the heating chamber, and the inlet of the reflux pump is connected to the outlet of the reflux valve through the internal channel. The filter is arranged close to the buffer chamber, and the outlet of the reflux pump is connected to the filter through the internal channel, and the outlet of the filter is connected to the buffer chamber through the internal channel.

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