An aerosol print head and a printing system having a print fluid material circulation function

Abstract

In order to solve the problem that the existing scheme of preventing the aerosol remaining in the nozzle from dropping on the substrate to contaminate the printed pattern on the surface of the substrate by setting a movable baffle, the overall printing equipment is large in size, the accessories are complex, and there is a small probability of shielding failure. Therefore, an aerosol nozzle is provided, and the improvement lies in: according to Bernoulli's principle, a high-speed airflow pipeline is arranged at the pipe section located at the front end of the nozzle upper shell on the aerosol conveying pipeline, the high-speed airflow pipeline is used for introducing high-speed compressed airflow to reduce the pressure above to form a pressure difference, one end of the high-speed airflow pipeline is a high-speed compressed airflow inlet, and the other end is connected with an aerosol recovery device or directly connected with the atmosphere.

Description

Technical Field

[0001] This invention relates to the field of rapid prototyping manufacturing technology, and specifically to a printhead and a printing system with a printing fluid material circulation function. Background Technology

[0002] Aerosol printing technology is an emerging additive manufacturing technology in recent years. Its principle is to use compressed air to impact or piezoelectric ultrasonic vibration to generate nanoscale micro aerosols from the printing fluid material. Then, the micro aerosols are sprayed onto the substrate surface by air pressure to deposit and form a shape, achieving nanoscale thickness and micrometer-level feature printing.

[0003] Currently, aerosol printing technology has the following drawbacks:

[0004] The aerosol ejected from the printhead is typically a cone-shaped mist with a circular spray point. The diameter of the aerosol is affected by the printing height, and it is easy to spray but difficult to control. When the trigger stops, the aerosol inside the printhead releases and drips.

[0005] Patent application number 200810082259.X discloses a continuous inkjet recording device that prints by ejecting ink from nozzles and recovers the ejected ink when printing is not in progress. To achieve ink recovery, this design incorporates grooves within the printhead to collect ink particles that do not participate in printing. It also includes a filter, a recovery solenoid valve, and a recovery pump in the grooves to draw residual ink from the nozzles into an ink container, thus achieving ink recovery. However, because this design uses a pump to directly draw ink from the liquid chamber to the ink dissolver, it is only suitable for non-volatile and non-diffusion fluid materials, resulting in significant limitations in ink recovery. For aerosol retraction, directly using a pump to recover aerosols from the printhead presents three problems: First, aerosol particles are randomly suspended in the air and will be drawn into the vacuum pump by negative pressure, making effective aerosol recovery impossible. Second, if the printing material is corrosive or an electrically charged printing fluid, it will corrode the pump body, posing a safety hazard. Third, directly using a pump to attract aerosol molecules to the ink collection bottle will disrupt the pressure balance of the printing fluid material in the ink collection bottle, negatively impacting the aerosol formation process. Therefore, this solution cannot be applied to the recovery of residual aerosols in the printhead.

[0006] Patent application US20090114151 A1 discloses an apparatus and method for maskless mesoscale material deposition. A computer-controlled movable baffle is installed at the nozzle exit. During printing, the baffle cuts out between the nozzle exit and the substrate, without affecting normal printing. After printing stops, the baffle cuts back into the space between the nozzle exit and the substrate, causing residual printing material inside the nozzle to drip onto the baffle, preventing it from directly falling onto the substrate surface and contaminating the printed pattern. However, this solution results in a large overall printing device size, complex components, and a small probability of baffle failure, adversely affecting printing continuity and stability. Furthermore, during the printing of nanoparticle materials, prolonged static placement can cause material agglomeration and sedimentation, affecting printing accuracy and stability, especially when using nanomaterials for printing. Summary of the Invention

[0007] One of the problems solved by this invention is that existing solutions that prevent residual aerosol in the nozzle from dripping onto the substrate and contaminating the printed pattern on the substrate surface by setting a movable baffle have the following drawbacks: the overall printing equipment is large and the accessories are complicated, and there is a small probability of occlusion failure. Therefore, an aerosol nozzle is provided.

[0008] The second problem further addressed by this invention is that existing aerosol printing equipment suffers from the technical problem that prolonged static placement during the printing of nanoparticle materials can lead to material agglomeration and sedimentation, affecting printing accuracy and stability. Therefore, this invention provides a printing system with a printing fluid material circulation function.

[0009] The technical solution of this invention is:

[0010] An aerosol printing nozzle includes an upper outer shell, a lower outer shell, and a nozzle arranged sequentially along the flow direction of the aerosol during printing; a sheath gas inlet disposed on the side wall of the upper outer shell; a focusing assembly disposed in the cavity formed by the upper outer shell and the lower outer shell; and an aerosol delivery pipeline passing through the upper outer shell, the focusing assembly, and the lower outer shell.

[0011] The focusing assembly has an air chamber and a sheath gas channel in the middle, which are used to transport the sheath gas introduced from the sheath gas inlet to the nozzle to encapsulate the aerosol that reaches the nozzle, so that it is focused into an aerosol beam and then ejected from the nozzle.

[0012] Its special feature is:

[0013] On the aerosol delivery pipeline, a high-speed airflow pipeline is provided at the pipe section at the front end of the outer shell of the nozzle. This high-speed airflow pipeline is used to introduce high-speed compressed airflow to reduce the pressure above it and form a pressure difference. One end of the pipeline is the high-speed compressed airflow inlet, and the other end is used to connect to the aerosol recovery device or directly connect to the atmosphere.

[0014] Furthermore, it also includes a filter; the filter is disposed on the aerosol delivery pipeline and located at the front end of the high-speed airflow pipeline.

[0015] Furthermore, the focusing assembly includes an upper focusing element and a lower focusing element; an inner air chamber is formed between the inner wall of the upper focusing element and the upper end of the lower focusing element, and an outer air chamber is formed between the upper focusing element, the outer shell of the nozzle head, and the lower focusing element; a plurality of air chamber holes are evenly opened on the side wall of the upper focusing element, and a pressure balancing device is installed in each air chamber hole; the middle of the outer shell of the nozzle head, the upper focusing element, the lower focusing element, and the lower shell of the nozzle head has a through hole along the axial direction for the aerosol delivery pipeline to pass through; the sheath gas channel is formed between the outer wall of the aerosol delivery pipeline and the inner wall of the middle through hole of the lower focusing element.

[0016] Furthermore, a sealing ring is installed between the inner wall of the through hole in the middle of the upper focusing component and the outer wall of the aerosol delivery pipeline.

[0017] A printing system with a printing fluid material circulation function includes an ink collector, an atomizer, a process cutoff device, and a printhead connected in sequence; its special feature is that the printhead adopts the above-mentioned aerosol printing printhead; the inlet of the aerosol delivery pipeline of the printhead is connected to the outlet of the process cutoff device.

[0018] Furthermore, it also includes an aerosol recovery device disposed between the atomizer and the nozzle; the inlet of the aerosol recovery device is connected to one end of the high-speed airflow pipeline of the nozzle, and the outlet is connected to the cavity of the atomizer, for recovering the drawn-back aerosol and rapidly releasing the high-speed airflow from the high-speed airflow pipeline to ensure its flow rate.

[0019] Furthermore, the aerosol recovery device includes an aerosol recovery pipe, an aerosol recovery box, a first printing fluid material recovery pipe, a pump, and a second printing fluid material recovery pipe arranged sequentially along the aerosol recovery flow path; one end of the aerosol recovery pipe is connected to one end of the high-speed airflow passage on the nozzle, and the other end extends into the aerosol recovery box; a recovery pressure balancing device is provided at the upper part of the aerosol recovery box to discharge the high-pressure high-speed airflow; one end of the first printing fluid material recovery pipe is located at the lower part of the aerosol recovery box, and the other end is connected to the cavity of the atomizer. When the recovered aerosol condenses into printing fluid material in the aerosol recovery box, the pump collects the printing fluid material from the aerosol recovery box into the atomizer.

[0020] Furthermore, a printing fluid material filter is provided on the second printing fluid material recovery pipe to filter impurities in the printing fluid material.

[0021] Furthermore, the ink collector includes an ink collection bottle, an ink collection tube, and an overflow valve; one end of the ink collection tube extends into the ink collection bottle and communicates with it, and the other end is connected to the pressure relief pipe of the overflow valve. The air inlet of the pressure relief pipe of the overflow valve is connected to the cavity of the atomizer through a connecting pipe; the ink collection bottle, the ink collection tube, and the overflow valve together constitute a pressure relief device.

[0022] Furthermore, the process cut-off device includes a solenoid valve and a nozzle air supply pipe; the solenoid valve is a distributed direct-acting two-position three-way solenoid valve, whose two air inlets are respectively connected to the air supply pipe and the air return pipe of the atomizer, and the air outlet is connected to one end of the nozzle air supply pipe; the other end of the nozzle air supply pipe is connected to the nozzle.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. This invention utilizes Bernoulli's principle by setting a high-speed airflow pipe near the aerosol inlet on the print head for high-speed compressed airflow. After printing stops, high-speed compressed airflow is introduced into this high-speed airflow pipe to generate negative pressure. This negative pressure draws back the residual aerosol in the print head. The drawn-back aerosol enters the high-speed airflow pipe through the aerosol delivery pipe, and then enters the aerosol recovery pipe and is sprayed into the aerosol recovery tank. Finally, it condenses into printing fluid material in the aerosol recovery tank and is recovered into the atomizer. This not only avoids the aerosol remaining in the print head dripping onto the substrate surface and contaminating the printed pattern, but also enables the recycling and reuse of printing materials, reducing printing material consumption, lowering printing costs, and improving the utilization rate of aerosols.

[0025] 2. In addressing the technical problem of residual aerosol dripping from the printhead onto the substrate surface and contaminating the printed pattern, this invention only requires a high-speed airflow pipe at the aerosol inlet of the printhead. By introducing high-speed compressed airflow into this pipe to create negative pressure, the residual aerosol within the printhead can be drawn back. Compared to the technical solution disclosed in patent application number US20090114151 A1, this invention has a simpler structure and smaller size because it eliminates the need for an additional movable baffle and its control drive mechanism. Compared to the technical solution disclosed in patent application number 200810082259.X, it eliminates the need for a dedicated absorption pump and a grooved structure within the printhead, resulting in lower improvement costs.

[0026] 3. The aerosol printhead with retraction function of the present invention has universality. It can be used not only in aerosol printing systems, but also in micro-droplet ejection devices such as paint spray nozzles and single-tube piezoelectric printheads. It can directly replace the printheads of these devices, enabling the printing system to have the function of retraction of printed fluid materials at a relatively low cost without changing other components of the existing printing system.

[0027] 4. This invention has no unnecessary mechanical parts, reducing the possibility of errors and improving stability; since this invention uses the negative pressure formed by high-speed compressed airflow to recover aerosols, and controls it synchronously with the cut-off device through electronic control, the printing continuity and reliability are better.

[0028] 5. The printing system of the present invention, through the coordinated use of a specially designed print head, an aerosol recovery device, a process cut-off device, and a pressure relief and recovery device, can realize the function of printing fluid material circulation. By regularly circulating the printing fluid material, the agglomeration and sedimentation of the printing fluid material caused by long-term static placement can be effectively avoided, thus improving printing accuracy and stability.

[0029] 6. This invention eliminates redundant mechanical structures and, based on the speed of the printhead movement and the requirements of the workpiece to be coated, achieves rapid aerosol printing and cut-off response through a solenoid valve, enabling precise and controllable printing material and avoiding defects such as over-spraying and under-spraying.

[0030] 7. The present invention adds multiple honeycomb-shaped pressure balancing devices to the airflow channel area between the inner and outer air chambers of the nozzle, reducing the unidirectional impact force of air pressure, making the pressure in the inner air chamber more uniform, thereby ensuring the uniformity of sheath airflow velocity, effectively reducing aerosol splashing caused by airflow impact, and improving the accuracy of printed image morphology.

[0031] 8. The present invention incorporates a precision filter on the air supply pipe of the printhead, which can reduce the dispersion of aerosol particle size, filter out large particles in the aerosol airflow, and leave smaller particles, thereby improving printing accuracy. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the aerosol jet printing device of the present invention.

[0033] Figure 2 This is a schematic diagram of the pressure relief device in the aerosol jet printing apparatus of the present invention.

[0034] Figure 3 This is a schematic diagram of the atomizer in the aerosol jet printing device of the present invention.

[0035] Figure 4 This is a schematic diagram of the process cut-off device in the aerosol jet printing apparatus of the present invention.

[0036] Figure 5 This is a schematic diagram of the nozzle structure in the aerosol jet printing device of the present invention.

[0037] Figure 6 This is a schematic diagram of the aerosol recovery device in the aerosol jet printing apparatus of the present invention.

[0038] Figure 7This is a schematic diagram of the recycling device in the aerosol jet printing apparatus of the present invention.

[0039] Figure label:

[0040] 1-Ink collector;

[0041] 11-Ink collecting bottle; 12-Ink receiving tube; 13-Overflow valve; 131-Pressure relief pipe; 14-Connecting pipe;

[0042] 2-Atomizer;

[0043] 21-Jet nozzle; 22-Left shell; 23-Guide block; 24-Fixing block; 25-Right shell; 26-Gas supply pipe; 27-Gas return pipe; 28-T-connector ink suction pipe; 281-Aerosol jet outlet; 282-Printing fluid material absorption port; 29-Bolt;

[0044] 3-Process cut-off device;

[0045] 31-Solenoid valve; 32-Nozzle air supply pipe;

[0046] 4-Sprayer head;

[0047] 41-Disc-shaped precision filter; 42-High-speed airflow channel; 43-Nozzle head outer shell; 44-Sheath gas inlet; 45-Upper focusing element; 46-Sealing ring; 47-Lower focusing element; 48-Nozzle head lower shell; 49-Bolt; 410-Sheath gas channel; 411-Nozzle; 412-Aerosol delivery pipeline; 413-Gas chamber orifice; 414-Pressure balancing device; 415-Outer gas chamber; 416-Inner gas chamber;

[0048] 5-Aerosol recovery device;

[0049] 51-Aerosol recovery tube; 52-Aerosol recovery box; 53-Recovery pressure balancing device; 54-First printing fluid material recovery tube; 55-Pump; 56-Printing fluid material filter; 57-Second printing fluid material recovery tube. Detailed Implementation

[0050] The present invention will be further described below with reference to the accompanying drawings.

[0051] like Figure 1 As shown, the printing system with printing fluid material circulation function provided by the present invention includes an ink collector 1, an atomizer 2, a process cutoff device 3 and a printhead 4 connected in sequence, and an aerosol recovery device 5 is provided between the printhead 4 and the atomizer 2.

[0052] like Figure 2As shown, the ink collector 1 includes an ink collection bottle 11, an ink collection tube 12, and an overflow valve 13; one end of the ink collection tube 12 extends into and communicates with the ink collection bottle 11, and the other end of the ink collection tube 12 is connected to the pressure relief pipe 131 of the overflow valve 13. The air inlet of the pressure relief pipe 131 of the overflow valve 13 is connected to the cavity of the atomizer 2 through a connecting pipe 14; the ink collection bottle 11, the ink collection tube 12, and the overflow valve 13 also constitute a pressure relief device. When the pressure inside the atomizer 2 chamber is less than the set pressure of the pressure relief valve 13, the pressure relief valve 13 is closed, and the pressure relief pipe 131 is not connected to the ink collection pipe 12. When the pressure inside the atomizer 2 chamber rises to the set pressure of the pressure relief valve, the overflow valve 13 opens, connecting the pressure relief pipe 131 to the ink collection pipe 12. A portion of the gas inside the atomizer 2 chamber enters the pressure relief pipe 131 first, and then enters the ink collection bottle 11 through the ink collection pipe 12. A small amount of printing fluid material carried in the gas collides with the bottom of the ink collection bottle 11 and remains in the ink collection bottle 11, thus completing the pressure relief of the printing system and the recovery of the printing fluid material.

[0053] like Figure 3 As shown, the atomizer 2 includes a left housing 22 and a right housing 25 that are joined together. The two are connected by bolts 29 to form an atomizer cavity. A jet port 21 is provided on the left housing 22. High-speed compressed air enters the atomizer cavity through the jet port 21 to atomize the printing fluid material. A guide block 23, a fixing block 24 and a three-way ink suction tube 28 are also provided in the atomizer cavity. The three-way ink suction tube 28 is located between the guide block 23 and the fixing block 24. The lower end of the three-way ink suction tube 28 is the printing fluid material absorption port 282. One end of the upper end of the three-way ink suction tube 28 is connected to the jet port 21, and the other end is the aerosol spray outlet 281. The atomizer 2 utilizes the Venturi effect to atomize the printing fluid material using pneumatic atomization. The printing fluid material flows into the three-way ink suction tube 28 through the printing fluid material absorption port 282. A high-speed compressed airflow enters the three-way ink suction tube 28 from the jet port 21. Due to the high flow velocity, the printing fluid material in the three-way ink suction tube 28 is ejected as an aerosol from the aerosol spray outlet 281 of the three-way ink suction tube 28, completing the process of attracting and atomizing the printing fluid material. The right housing 25 of the atomizer 2 also has parallel air supply pipes 26 and 27, both connected to the atomizer cavity. The air supply pipe 26 is used to output the aerosol generated by the atomizer 2 from the atomizer cavity, and the 27 is used to return the aerosol to the atomizer 2 after printing stops.

[0054] like Figure 4As shown, the process cutoff device 3 includes a solenoid valve 31 and a nozzle air supply pipe 32. The solenoid valve 31 is used to stop the delivery of aerosol to the nozzle 4 in a timely manner after printing. Specifically, the solenoid valve 31 can be a distributed direct-acting two-position three-way solenoid valve. Its two air inlets are connected to the air supply pipe 26 and the return air pipe 27 of the atomizer 2, respectively, and its air outlet is connected to one end of the nozzle air supply pipe 32. The other end of the nozzle air supply pipe 32 is connected to the nozzle 4.

[0055] like Figure 5 As shown, the printhead 4 includes a butterfly-shaped precision filter 41, an upper outer shell 43, a lower outer shell 48, and a nozzle 411 arranged sequentially along the aerosol flow direction during printing. The precision filter 41 is installed on the air supply pipe 32 of the printhead and is used to filter impurities in the aerosol to prevent them from clogging the nozzle 411. The upper outer shell 43 and the lower outer shell 48 are joined vertically and fixedly connected by bolts 49. A sheath air inlet 44 is provided on the upper side wall of the upper outer shell 43. An upper focusing element 45 and a lower focusing element 47 are also provided in the cavity formed by the upper outer shell 43 and the lower outer shell 48. The lower end of component 45 is threadedly connected to the upper end of the lower focusing component 47, and the lower end of the lower focusing component 47 is fixedly connected to the lower housing 48 of the nozzle. An inner air chamber 416 is formed between the inner wall of the upper focusing component 45 and the upper end of the lower focusing component 47, and an outer air chamber 415 is formed between the upper focusing component 45, the upper housing 43 of the nozzle, and the lower focusing component 47. Four air chamber holes 413 are evenly opened on the side wall of the upper focusing component 45, and a honeycomb-shaped pressure balancing device 414 is installed in each air chamber hole 413, so that the sheath gas in the outer air chamber 415 can enter the inner air chamber 416 evenly, balancing the air pressure in the inner air chamber 416, which is beneficial. To prevent aerosol accumulation, the nozzle head housing 43, upper focusing element 45, lower focusing element 47, and lower nozzle housing 48 have axial through holes in their middle sections. An aerosol delivery pipe 412 is installed within these through holes, penetrating the nozzle head housing 43, upper focusing element 45, lower focusing element 47, and lower nozzle housing 48. The upper outer wall of the aerosol delivery pipe 412 is threadedly connected to the central through hole of the upper focusing element 45. The upper port of the aerosol delivery pipe 412 is connected to and communicates with the nozzle air supply pipe 32, and the lower port of the aerosol delivery pipe 412 is connected to the nozzle 411. The outer wall of the aerosol delivery pipe 412 is connected to the lower nozzle 411. A sheath gas channel is formed between the inner wall of the central through hole of the focusing element 47 and the inner wall of the central through hole of the lower outer shell of the nozzle. A high-speed airflow pipe 42 is provided on the aerosol delivery pipe 412 at the section between the precision filter 41 and the outer shell 43 of the nozzle. The high-speed airflow pipe 42 is used to introduce high-speed compressed airflow. One end of the high-speed compressed airflow is the inlet of the high-speed compressed airflow, and the other end is used to connect to the aerosol recovery device 5. In order to prevent the sheath gas from entering the disc-shaped precision filter 41 and mixing with the aerosol, a sealing ring 46 is also installed between the inner wall of the central through hole of the upper focusing element 45 and the outer wall of the aerosol delivery pipe 412.

[0056] like Figure 6 As shown, the aerosol recovery device 5 includes an aerosol recovery pipe 51, an aerosol recovery tank 52, a first printing fluid material recovery pipe 54, a pump 55, and a second printing fluid material recovery pipe 57 arranged sequentially along the aerosol recovery flow path. One end of the aerosol recovery pipe 51 is connected to one end of the high-speed airflow passage 42 on the nozzle 4, and the other end extends into the aerosol recovery tank 52. A recovery pressure balancing device 53 is also provided at the upper part of the aerosol recovery tank 52 to discharge the high-pressure, high-speed airflow. One end of the first printing fluid material recovery pipe 54 is located at the lower part of the aerosol recovery tank 52, and the other end is connected to the cavity of the atomizer 2. When the recovered aerosol condenses into printing fluid material in the aerosol recovery tank 52, the pump 55 collects the printing fluid material from the aerosol recovery tank 52 into the atomizer 2. A printing fluid material filter 56 is also provided on the second printing fluid material recovery pipe 57 to filter impurities in the printing fluid material.

[0057] To facilitate observation of the recovery progress of the printing fluid material, as well as the amount of printing fluid material and the movement of aerosols inside the atomizer 2 housing, the ink collection bottle 11, the housing of the atomizer 2, and the aerosol recovery box 52 in the aerosol recovery device 5 are made of organic transparent glass.

[0058] The principle and working process of this invention:

[0059] Atomizer 2 utilizes the Venturi effect to atomize the printing fluid material using pneumatic atomization. A high-speed compressed airflow enters the three-way ink suction tube 28 from the jet port 21. Due to the high velocity of the compressed airflow, the pressure at the top of the three-way ink suction tube 28 decreases, creating a pressure difference that draws the printing fluid material into the three-way ink suction tube 28 through the printing fluid material absorption port 282. The printing fluid material drawn into the three-way ink suction tube 28 encounters the high-speed compressed airflow introduced from the jet port 21, which overcomes the surface tension of the printing fluid material, causing it to decompose into small droplets that are ejected from the aerosol spray outlet 281 and suspended in the air. Large droplets collide with the inner wall of the three-way ink suction tube and are returned to the printing fluid material, while small droplets, together with the carrier airflow, form an aerosol that enters the air supply pipe 26. During this process, the ink collector 1 uses an overflow valve 13 to depressurize the cavity of atomizer 2 and recover the droplets.

[0060] When the printing device is working normally, the solenoid valve 31 is not energized, and its valve core blocks the air inlet connected to the return air pipe 27. The aerosol generated by the atomizer 2 enters the air inlet of the solenoid valve 31 through the air supply pipe 26, and then enters the nozzle air supply pipe 32 through the air outlet. Then, it passes through the disc-shaped precision filter 41 to filter out large particles in the aerosol airflow, leaving smaller particles and reducing the dispersion of aerosol particle size. The filtered aerosol gas enters the aerosol channel 412 and reaches the nozzle 411 through the aerosol delivery pipeline 412.

[0061] When the printing system starts working, sheath gas is introduced into the outer air chamber 415 through the sheath gas inlet 44. After the outer air chamber 415 is full, the sheath gas enters the inner air chamber 416 through the air chamber hole 413 and the pressure balancing device 414. The sheath gas in the inner air chamber 416 enters the nozzle 411 along the sheath gas channel 410 formed by the aerosol delivery pipeline 412, the upper focusing element 45 and the lower focusing element 47, and surrounds the aerosol. The aerosol surrounded by sheath gas will not directly contact the inner wall of the nozzle 411 and can be focused into an aerosol beam. Finally, it is ejected through the nozzle 411 to realize the aerosol printing work.

[0062] During printing, a high-speed compressed airflow is constantly flowing into the atomizer 2 chamber, which causes the pressure inside the atomizer chamber to rise over time. When the pressure inside the atomizer chamber rises to the set pressure of the overflow valve 13, the valve of the overflow valve 13 opens, and part of the gas inside the atomizer chamber enters the pressure relief pipe 131, and then enters the ink collection bottle 11 through the ink collection pipe 12. A small amount of printing fluid material carried in the gas collides with the bottom of the bottle and remains in the bottle. The remaining gas is released into the atmosphere through the top of the ink collection bottle 11, thus completing the depressurization of the system and the recovery of droplets.

[0063] When the printing system stops printing, the sheath gas inlet 44 stops supplying sheath gas, the solenoid valve 31 is energized, and its valve core moves to block the nozzle air supply pipe 32. The solenoid valve 31 connects the air supply pipe 26 with the return air pipe 27, so that the area from the nozzle air supply pipe 32 to the nozzle 411 is in a state of no external force. The aerosol flows back to the atomizer 2 through the return air pipe 27, stopping the delivery of aerosol gas. At the same time, using Bernoulli's principle, a high-speed airflow with a pressure of more than 0.1MPa (optimal 0.15-0.25MPa) is introduced into the high-speed airflow pipe 42, bringing the aerosol above the high-speed airflow pipe 42 into the high-speed airflow pipe 42. The introduced high-speed airflow reduces the pressure above the high-speed airflow channel 42, creating a negative pressure relative to the bottom. The aerosol below the high-speed airflow channel 42 is attracted by the pressure difference and moves upward along the aerosol delivery pipe 412, finally entering the high-speed airflow channel 42, completing the stop of the printing work and avoiding over-printing. To ensure sufficient negative pressure is generated, the pressure required to generate negative pressure can be detected, and the flow rate of the high-speed airflow can be adjusted based on the detected pressure to ensure reliable recovery.

[0064] Aerosols attracted by the high-speed airflow are sprayed into the aerosol recovery tank 52 through the aerosol recovery pipe 51. The printing fluid material contained in the compressed air condenses at the bottom of the aerosol recovery tank 52 under gravity, causing the pressure in the aerosol recovery tank 52 to increase. The high-speed airflow is then quickly released by the recovery pressure balancing device 53 located at the top of the aerosol recovery tank 52, thus ensuring the airflow velocity within the high-speed airflow channel 42 and completing the aerosol retraction and collection. After the aerosols in the aerosol recovery tank 52 condense into printing fluid material, the printing fluid material is collected from the aerosol recovery tank 52 into the atomizer 2 by the pump 55, achieving aerosol interception and recycling of the printing fluid material.

Claims

1. A printing system having a function of circulating a printing fluid material, comprising, in series, an ink catcher, an atomizer, a process cut-off device, and a nozzle head; characterized in that: The nozzle comprises, in sequence along the flow direction of the aerosol during printing, a nozzle upper housing, a nozzle lower housing and a nozzle, a sheath gas inlet provided on the side wall of the nozzle upper housing, a focusing assembly provided in the cavity formed by the nozzle upper housing and the nozzle lower housing, and an aerosol delivery pipeline penetrating through the nozzle upper housing, the focusing assembly and the nozzle lower housing; The focusing assembly is provided with an air chamber and a sheath gas channel in the middle, which is used to deliver the sheath gas introduced from the sheath gas inlet to the nozzle to wrap the aerosol reaching the nozzle, so that the aerosol is focused into an aerosol beam and then sprayed from the nozzle; A high-speed airflow pipeline is provided on the aerosol delivery pipeline at the tube segment at the front end of the nozzle upper housing, which is used to introduce high-speed compressed airflow to form a pressure difference by reducing the pressure above the high-speed compressed airflow, and has one end as a high-speed compressed airflow inlet and the other end connected with an aerosol recovery device or directly connected with the atmosphere. The inlet of the aerosol delivery pipeline of the nozzle is connected with the outlet of the process cutoff device; An aerosol recovery device is provided between the atomizer and the nozzle, the inlet of the aerosol recovery device is connected with one end of the high-speed airflow pipeline of the nozzle, and the outlet is connected with the cavity of the atomizer, which is used to recover the suctioned aerosol and quickly release the high-speed airflow from the high-speed airflow pipeline to ensure the flow rate.

2. The printing system having a function of circulating a printing fluid material according to claim 1, characterized by: The aerosol recovery device comprises, in sequence along the aerosol recovery flow path, an aerosol recovery tube, an aerosol recovery tank, a first printing fluid material recovery tube, a pump and a second printing fluid material recovery tube; one end of the aerosol recovery tube is connected with one end of the high-speed airflow passage of the nozzle, and the other end extends into the aerosol recovery tank; a recovery pressure balancing device is provided at the upper part of the aerosol recovery tank, which is used to discharge the high-pressure high-speed airflow; one end of the first printing fluid material recovery tube is arranged at the lower part of the aerosol recovery tank, and the other end is in communication with the cavity of the atomizer, so that when the recovered aerosol condenses into printing fluid material in the aerosol recovery tank, the printing fluid material is collected from the aerosol recovery tank to the atomizer by the pump.

3. The printing system having a function of circulating a printing fluid material according to claim 2, characterized by: A printing fluid material filter is provided on the second printing fluid material recovery tube, which is used to filter impurities in the printing fluid material.

4. The printing system having a function of circulating a printing fluid material according to claim 3, characterized by: The ink collector comprises an ink collecting bottle, an ink collecting tube and an overflow valve; one end of the ink collecting tube extends into the ink collecting bottle and is in communication therewith, and the other end is connected with the pressure relief pipeline of the overflow valve; the air inlet of the pressure relief pipeline of the overflow valve is connected with the cavity of the atomizer through a connecting pipe; the ink collecting bottle, the ink collecting tube and the overflow valve constitute a cutoff pressure relief device at the same time.

5. The printing system having a function of circulating a printing fluid material according to claim 4, characterized by: The process cutoff device comprises an electromagnetic valve and a nozzle gas delivery pipeline; The electromagnetic valve is a distributed direct-acting two-position three-way electromagnetic valve, two gas inlets of which are connected with the gas delivery pipeline and the gas return pipeline of the atomizer respectively, and the gas outlet is connected with one end of the nozzle gas delivery pipeline; the other end of the nozzle gas delivery pipeline is connected with the nozzle.

6. The printing system having a function of circulating a printing fluid material according to any one of claims 1 to 5, characterized by: A filter is further provided; the filter is arranged on the aerosol delivery pipeline and located at the front end of the high-speed airflow pipeline.

7. The printing system having a function of circulating a printing fluid material according to claim 6, characterized by: The focusing assembly comprises an upper focusing member and a lower focusing member; An inner air chamber is formed between the inner wall of the upper focusing member and the upper end of the lower focusing member, and an outer air chamber is formed between the upper focusing member, the upper nozzle shell and the lower focusing member; a plurality of air chamber holes are evenly formed on the side wall of the upper focusing member, and a pressure balancing device is installed in each air chamber hole; the upper nozzle shell, the upper focusing member, the lower focusing member and the lower nozzle shell have a through hole in the middle part along the axial direction for the aerosol delivery pipeline to pass through; the outer wall of the aerosol delivery pipeline and the inner wall of the middle part through hole of the lower focusing member form the sheath gas channel.

8. The printing system having a function of circulating a printing fluid material according to claim 7, characterized by: A sealing ring is installed between the inner wall of the middle part through hole of the upper focusing member and the outer wall of the aerosol delivery pipeline.

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