Media anti-mixing switching and automatic cleaning 3D printing inkjet system and method

Abstract

The present application relates to 3D printing ink supply and nozzle cleaning technology, specifically discloses a medium anti-mixing switching and automatic cleaning 3D printing ink system and method. The system comprises resin liquid supply pipe, cleaning liquid supply pipe, common liquid supply pipe, piezoelectric nozzle, anti-mixing component, control component, resin recovery pipe, waste liquid collection pipe and controller. Anti-mixing component first cuts off common liquid supply pipe when resin liquid supply and cleaning liquid supply are switched, and residual medium in the component is discharged into waste liquid collection pipe; control component first isolates piezoelectric nozzle when switching to cleaning liquid supply, and reusable resin in common liquid supply pipe is introduced into resin recovery pipe, and the transition mixed liquid formed subsequently is introduced into waste liquid collection pipe. The controller combines cleaning liquid cumulative delivery volume and medium detection result to judge resin recovery end point and cleaning liquid reaching state, and makes cleaning liquid enter piezoelectric nozzle for replacement after the preset cleaning liquid judgment condition is met, so as to realize liquid medium anti-mixing switching, resin recovery and nozzle automatic cleaning.

Description

Technical Field

[0001] This invention belongs to the field of 3D inkjet printing technology, and specifically relates to a 3D printing inkjet system and method for media anti-mixing switching and automatic cleaning. Background Technology

[0002] 3D printing equipment for casting sand molds typically uses piezoelectric nozzles to selectively spray furan resin onto the molding sand layer, causing the sand in the corresponding areas to bond and form the desired shape. When the equipment finishes printing or needs to be shut down for an extended period, in order to prevent the furan resin from remaining inside the nozzle for a long time and causing increased viscosity, film formation, or agglomeration, it is usually necessary to clean the liquid supply pipeline and piezoelectric nozzle with a cleaning solution.

[0003] In existing liquid supply systems, when switching from resin supply to cleaning fluid supply, the resin supply pipe and the cleaning supply pipe typically switch directly. Resin remains in the switching area and in the subsequent common supply pipe. When the cleaning fluid enters, it pushes the existing resin towards the piezoelectric nozzle, forming a transitional mixture between the resin and the cleaning fluid. If this transitional mixture directly enters the piezoelectric nozzle, it increases the displacement load within the nozzle cavity and alters the composition of the medium entering the nozzle. If all the medium in the common supply pipe is discharged as waste, it results in the waste of resin that has not yet been significantly affected by mixing.

[0004] Furthermore, relying solely on fixed cleaning intervals for liquid supply switching makes it difficult to accurately determine whether the resin in the common supply pipe has been discharged and whether the cleaning fluid has reached the upstream of the printhead. Therefore, it is necessary to provide a 3D printing inkjet system that can reduce mixing during media switching, separately treat reusable resin and transition mixture, and clean the piezoelectric printhead only after confirming the arrival of the cleaning fluid. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a 3D printing inkjet system and method for media anti-mixing switching and automatic cleaning. To achieve the above objectives, this invention employs the following technical solutions:

[0006] In a first aspect, the present invention provides a 3D printing inkjet system with media anti-mixing switching and automatic cleaning, comprising a resin supply pipe for providing furan resin, a cleaning supply pipe for providing cleaning fluid, a common supply pipe connected to the resin supply pipe and the cleaning supply pipe, and a piezoelectric printhead connected to the common supply pipe. An anti-mixing component is provided between the resin supply pipe, the cleaning supply pipe and the common supply pipe, and the anti-mixing component is also connected to a waste liquid collection pipe. A control component is also provided between the common supply pipe and the piezoelectric printhead, and the control component is also connected to a resin recovery pipe and the waste liquid collection pipe. The inkjet system further includes a controller that is signal-connected to the anti-mixing component and the control component respectively.

[0007] The anti-mixing component is used to switch the connection status of the resin supply pipe and the cleaning supply pipe with the common supply pipe. When switching, it is first disconnected from the common supply pipe. After the residual medium in the anti-mixing component is introduced into the waste liquid collection pipe, it is then connected to the common supply pipe.

[0008] The control component is used to switch the connection state between the common liquid supply pipe and the piezoelectric nozzle. When switching from resin supply to cleaning liquid supply, it is first disconnected from the piezoelectric nozzle, the reusable resin is introduced into the resin recovery pipe, and the transition mixture formed by the resin and the cleaning liquid is introduced into the waste liquid collection pipe. After the flowing medium meets the preset cleaning liquid judgment conditions, it is then connected to the piezoelectric nozzle.

[0009] Furthermore, the anti-mixing component includes a mixing chamber, a first opening and closing element and a second opening and closing element for controlling the on / off state of the resin supply pipe and the cleaning supply pipe, respectively, and a third opening and closing element for controlling the on / off state of the anti-mixing component and the common supply pipe. The mixing chamber is connected to the waste liquid collection pipe, and a fourth opening and closing element is provided at the connection.

[0010] Furthermore, the control assembly includes a flow chamber communicating with the common liquid supply pipe, and a resin recovery valve, a waste liquid valve, and a nozzle isolation valve for controlling the connection and disconnection between the flow chamber and the resin recovery pipe, the waste liquid collection pipe, and the piezoelectric nozzle, respectively; the valve seat of the nozzle isolation valve is located near the piezoelectric nozzle.

[0011] Furthermore, the cleaning supply pipe is equipped with a flow detection device, and the control component also includes a medium detection device for detecting the state of the flowing medium. The flow detection device and the medium detection device are signal-connected to the controller.

[0012] Furthermore, the controller is configured to: determine the cumulative delivery amount of cleaning fluid based on the detection result of the flow detection element, and determine a preset recovery amount based on the effective volume of the flow path between the anti-mixing component and the medium detection element; when the cumulative delivery amount reaches the preset recovery amount, or when the detection value of the medium detection element leaves the preset resin characteristic range, close the resin recovery valve and open the waste liquid valve; when the detection value of the medium detection element enters the preset cleaning fluid characteristic range and remains there for a preset duration, determine that the flowing medium meets the preset cleaning fluid determination condition.

[0013] Furthermore, the medium detection element is positioned near the valve seat of the resin recovery valve, the waste liquid valve, and the nozzle isolation valve.

[0014] Secondly, the present invention also provides a media anti-mixing switching and automatic cleaning method for a 3D printing inkjet system applicable to the above-mentioned system. When the system switches from resin supply to cleaning fluid supply, the method includes the following steps:

[0015] The control component is used to disconnect the common liquid supply pipe from the piezoelectric nozzle.

[0016] The anti-mixing component is controlled to disconnect the resin supply pipe and the cleaning supply pipe from the common supply pipe, and the residual medium in the anti-mixing component is introduced into the waste liquid collection pipe, and then the cleaning supply pipe is connected to the common supply pipe.

[0017] With the common liquid supply pipe and the piezoelectric nozzle kept isolated, the common liquid supply pipe is connected to the resin recovery pipe, and the cleaning fluid pushes the resin in the common liquid supply pipe and introduces the reusable resin into the resin recovery pipe.

[0018] After the recycling of the reusable resin is completed based on the cumulative delivery volume of the cleaning fluid and the detection results of the flowing medium, the common supply pipe is isolated from the resin recycling pipe and connected to the waste liquid collection pipe, and the transition mixture formed by the resin and the cleaning fluid is introduced into the waste liquid collection pipe.

[0019] When the detection result of the flowing medium meets the preset cleaning fluid determination conditions, the common liquid supply pipe is isolated from the waste liquid collection pipe and connected to the piezoelectric nozzle to supply cleaning fluid to the piezoelectric nozzle to replace the residual resin in the piezoelectric nozzle.

[0020] Furthermore, determining the end of the recycling of the reusable resin based on the cumulative delivery volume of the cleaning fluid and the detection results of the flowing medium includes:

[0021] The flow rate of the cleaning fluid is detected by a flow detection device installed on the cleaning fluid supply pipe. From the time the cleaning fluid supply pipe is connected to the common fluid supply pipe, the cumulative delivery amount of the cleaning fluid is determined based on the detection result of the flow detection device. The medium flowing through the control component is detected by a medium detection device installed on the control component.

[0022] A preset recovery amount is determined based on the effective volume of the flow path between the anti-mixing component and the medium detection element. When the cumulative delivery amount reaches the preset recovery amount, or when the detection value of the medium detection element leaves the preset resin characteristic range, the recovery of the reusable resin is determined to be completed.

[0023] The preset cleaning fluid determination conditions include: the detection value of the medium detection element enters the preset cleaning fluid characteristic range and remains there for a preset duration.

[0024] Furthermore, it also includes a step of reverting from a cleaning solution supply to a resin supply:

[0025] The control component is used to disconnect the common liquid supply pipe from the piezoelectric nozzle.

[0026] The anti-mixing component is controlled to disconnect the resin supply pipe and the cleaning supply pipe from the common supply pipe, and the residual cleaning liquid in the anti-mixing component is introduced into the waste liquid collection pipe, and then the resin supply pipe is connected to the common supply pipe.

[0027] With the common liquid supply pipe and the piezoelectric nozzle kept isolated, the common liquid supply pipe is connected to the waste liquid collection pipe, so that the resin pushes the cleaning liquid in the common liquid supply pipe and the reverse transition mixture formed by the resin and the cleaning liquid into the waste liquid collection pipe.

[0028] When the detection result of the flowing medium enters the preset resin characteristic range and continues for a preset time, the common liquid supply pipe is isolated from the waste liquid collection pipe and connected to the piezoelectric nozzle to supply resin to the piezoelectric nozzle to replace the cleaning fluid in the piezoelectric nozzle.

[0029] In summary, this application has at least the following beneficial technical effects:

[0030] Compared with the existing method of directly switching between resin supply and cleaning fluid supply, the present invention sets up an anti-mixing component between the resin supply pipe, the cleaning supply pipe and the common supply pipe. When switching the supply medium, the common supply pipe is first isolated, and the residual medium in the anti-mixing component is introduced into the waste liquid collection pipe before the supply pipe is connected, thereby reducing cross-mixing caused by residual medium in the switching area from the source.

[0031] By setting up a control component between the common supply pipe and the piezoelectric nozzle, the piezoelectric nozzle is isolated first during the media switching process. The reusable resin in the common supply pipe is then introduced into the resin recovery pipe, and the subsequently formed transition mixture is introduced into the waste liquid collection pipe. This reduces the waste of usable resin while preventing a large volume of transition mixture from directly entering the piezoelectric nozzle.

[0032] Furthermore, the endpoint of resin recovery and the state of cleaning fluid arrival are determined by the cumulative delivery volume of cleaning fluid and the results of media detection. Cleaning fluid is then supplied to the piezoelectric nozzle only after the media flowing through it meets the preset cleaning fluid judgment conditions, so that the media replacement in the common supply pipe and the cleaning of the nozzle cavity form a continuous and controlled switching process.

[0033] Therefore, the present invention can improve the controllability of resin and cleaning fluid switching, reduce the displacement load of residual resin and mixed media in the nozzle, and take into account resin recycling and automatic nozzle cleaning, making it suitable for continuous operation and shutdown maintenance of 3D printing equipment. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram illustrating the working principle of a 3D printing inkjet system with media anti-mixing switching and automatic cleaning, provided in an embodiment of the present invention.

[0036] Figure 2 This is a schematic diagram of the cleaning process of a media anti-mixing switching and automatic cleaning 3D printing inkjet method provided in an embodiment of the present invention;

[0037] Figure 3 This is a schematic diagram of the recovery process of a media anti-mixing switching and automatic cleaning 3D printing inkjet method provided in an embodiment of the present invention.

[0038] Reference numerals: 1. Anti-mixing component; 2. Control component; 3. Resin supply pipe; 4. Cleaning supply pipe; 5. Common supply pipe; 6. Piezoelectric nozzle; 7. Controller; 8. Flow detection element; 11. First opening and closing element; 12. Second opening and closing element; 13. Mixing relief chamber; 14. Fourth opening and closing element; 15. Third opening and closing element; 16. Waste liquid collection pipe; 21. Flow chamber; 22. Nozzle isolation valve; 23. Resin recovery valve; 24. Waste liquid valve; 25. Resin recovery pipe; 26. Medium detection element. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be noted that the following embodiments are used to illustrate the technical solutions of the present invention, and not to limit the scope of protection of the present invention. Without departing from the technical concept of the present invention, equivalent substitutions or adaptive adjustments made by those skilled in the art to the specific structure, installation position, and control parameters of each component are all possible implementations of the present invention.

[0040] The resin described in this embodiment is furan resin used for bonding molding sand in 3D printing of casting sand molds. The cleaning solution is a liquid medium capable of dissolving, diluting, or displacing the furan resin and compatible with the internal flow channels, seals, and nozzle materials of the piezoelectric nozzle. The cleaning solution may also have a moisturizing effect. For ease of explanation, it will be referred to as cleaning solution below.

[0041] Example 1

[0042] like Figure 1As shown, this embodiment provides a 3D printing inkjet system with media anti-mixing switching and automatic cleaning, including a resin supply pipe 3, a cleaning supply pipe 4, a common supply pipe 5, an anti-mixing component 1, a waste liquid collection pipe 16, a control component 2, a resin recovery pipe 25, a piezoelectric printhead 6, and a controller 7.

[0043] The inlet end of the resin supply pipe 3 is connected to the resin storage container via a resin supply pump, and the inlet end of the cleaning supply pipe 4 is connected to the cleaning solution storage container via a cleaning supply pump. The resin supply pump and the cleaning supply pump are used to deliver the medium to the resin supply pipe 3 and the cleaning supply pipe 4 respectively according to their respective operating conditions.

[0044] The resin supply pipe 3 and the cleaning supply pipe 4 are respectively connected to the medium input side of the anti-mixing component 1, and the common supply pipe 5 is connected to the medium output side of the anti-mixing component 1, so that the resin supply pipe 3 or the cleaning supply pipe 4 can be connected to the common supply pipe 5 through the anti-mixing component 1. The other end of the common supply pipe 5 is connected to the piezoelectric nozzle 6 through the control component 2.

[0045] The anti-mixing component 1 is also connected to the waste liquid collection pipe 16 to discharge residual media inside the anti-mixing component 1. The control component 2 is connected to the resin recovery pipe 25 and the waste liquid collection pipe 16 respectively, and is used to guide the media in the common supply pipe 5 to the resin recovery pipe 25, the waste liquid collection pipe 16 or the piezoelectric nozzle 6 according to the media switching stage.

[0046] The outlet of the resin recovery pipe 25 can be connected to a resin recovery container. Preferably, the resin recovery container is independent of the resin storage container at the inlet of the resin supply pipe 3. The recovered resin is first stored in the resin recovery container, and after testing to ensure it meets preset reuse conditions, it is used for subsequent printing, rather than being directly returned to the resin storage container. The outlet of the waste liquid collection pipe 16 is connected to a waste liquid collection container. Residual media discharged from the anti-mixing component 1 and transition mixture discharged from the control component 2 can both enter the waste liquid collection container through the waste liquid collection pipe 16.

[0047] The controller 7 is signal-connected to both the anti-mixing component 1 and the control component 2. The controller 7 can send opening and closing commands to the anti-mixing component 1 and the control component 2 to control the opening and closing of the corresponding flow paths. In a preferred embodiment, the first opening / closing element 11, the second opening / closing element 12, the third opening / closing element 15, and the fourth opening / closing element 14, as well as the resin recovery valve 23, the waste liquid valve 24, and the nozzle isolation valve 22, are each equipped with a valve position detection element. The valve position detection element is used to send the actual opening / closing state of the corresponding valve to the controller 7.

[0048] The controller 7 can be a programmable logic controller, a microcontroller, or an industrial control computer. It internally stores the control programs and judgment parameters corresponding to normal printing, media switching, resin recovery, transition mixture discharge, printhead cleaning, and printing resumption.

[0049] The anti-mixing component 1 includes a mixing chamber 13, a first opening and closing element 11, a second opening and closing element 12, a third opening and closing element 15, and a fourth opening and closing element 14. The first opening and closing element 11 is disposed on the medium flow path corresponding to the resin supply pipe 3 and is used to control the opening and closing of the resin supply pipe 3. The second opening and closing element 12 is disposed on the medium flow path corresponding to the cleaning supply pipe 4 and is used to control the opening and closing of the cleaning supply pipe 4. The third opening and closing element 15 is disposed between the anti-mixing component 1 and the common supply pipe 5 and is used to control the opening and closing of the connection between the anti-mixing component 1 and the common supply pipe 5.

[0050] The mixing chamber 13 is disposed between the first opening and closing element 11, the second opening and closing element 12, and the third opening and closing element 15. The mixing chamber 13 is connected to the resin supply pipe 3 and the cleaning supply pipe 4 through the first opening and closing element 11 and the second opening and closing element 12, respectively, and is connected to the common supply pipe 5 through the third opening and closing element 15. The mixing chamber 13 is also connected to the waste liquid collection pipe 16. A fourth opening and closing element 14 is disposed between the mixing chamber 13 and the waste liquid collection pipe 16. The fourth opening and closing element 14 is used to control the opening and closing of the mixing chamber 13 and the waste liquid collection pipe 16.

[0051] In this embodiment, the first opening / closing element 11, the second opening / closing element 12, the third opening / closing element 15, and the fourth opening / closing element 14 can all be solenoid valves. Each opening / closing element preferably adopts a low-retention structure to reduce media residue in the valve cavity and sealing parts. Each opening / closing element can also be a pneumatic valve or a hydraulic valve, as long as it can realize the opening and closing of the corresponding flow path.

[0052] The anti-mixing component 1 has at least a resin supply state, an intermediate isolation and mixing state, and a cleaning fluid supply state.

[0053] When the resin is in the supply state, the first opening and closing element 11 and the third opening and closing element 15 are open, and the second opening and closing element 12 and the fourth opening and closing element 14 are closed. The furan resin enters the mixing chamber 13 through the resin supply pipe 3 via the first opening and closing element 11, and enters the common supply pipe 5 through the third opening and closing element 15.

[0054] When in the intermediate isolation and venting state, the first opening and closing element 11, the second opening and closing element 12, and the third opening and closing element 15 are all closed, and the fourth opening and closing element 14 is open. At this time, the resin supply pipe 3 and the cleaning supply pipe 4 are both isolated from the common supply pipe 5, and a drainage passage is formed between the venting chamber 13 and the waste liquid collection pipe 16. The residual medium in the venting chamber 13 enters the waste liquid collection pipe 16 under the action of residual pressure in the chamber, gravity, or the fluid pressure difference formed by suction at the waste liquid end.

[0055] When the cleaning fluid is in the supply state, the second opening and closing element 12 and the third opening and closing element 15 are opened, and the first opening and closing element 11 and the fourth opening and closing element 14 are closed. The cleaning fluid enters the mixing chamber 13 through the second opening and closing element 12 from the cleaning supply pipe 4, and enters the common supply pipe 5 through the third opening and closing element 15.

[0056] When switching from resin supply to cleaning fluid supply, first close the first and third opening / closing components 11 and 15, and keep the second opening / closing component 12 closed. Then open the fourth opening / closing component 14 to put the anti-mixing assembly 1 into the intermediate isolation and mixing-free state. After the residual resin in the mixing-free chamber 13 is discharged into the waste liquid collection pipe 16, close the fourth opening / closing component 14, and then open the second and third opening / closing components 12 and 15 to connect the cleaning fluid supply pipe 4 with the common fluid supply pipe 5.

[0057] Accordingly, when reverting from the cleaning fluid supply state to the resin supply state, the second and third opening / closing elements 12 and 15 are closed first, while the first opening / closing element 11 remains closed. Then, the fourth opening / closing element 14 is opened to guide the residual cleaning fluid in the mixing chamber 13 into the waste fluid collection pipe 16. After the drainage is completed, the fourth opening / closing element 14 is closed, and the first and third opening / closing elements 11 and 15 are opened again to connect the resin supply pipe 3 with the common supply pipe 5.

[0058] Therefore, the supply of resin supply pipe 3 and cleaning supply pipe 4 is not directly switched. Instead, an intermediate state is formed between the two supply states, in which resin supply pipe 3, cleaning supply pipe 4 and common supply pipe 5 are isolated from each other. This prevents the residual medium inside the anti-mixing component 1 from being directly carried into the common supply pipe 5 when the new medium is introduced.

[0059] Preferably, a mechanical linkage mechanism or an electrical interlock is provided between the first opening / closing element 11 and the second opening / closing element 12 to prevent the first opening / closing element 11 and the second opening / closing element 12 from opening simultaneously. The controller 7 can also be configured to allow the fourth opening / closing element 14 to open only after detecting that the first opening / closing element 11, the second opening / closing element 12, and the third opening / closing element 15 are all closed; and to allow the third opening / closing element 15 to open only after detecting that the fourth opening / closing element 14 is closed.

[0060] The control component 2 is located between the common liquid supply pipe 5 and the piezoelectric nozzle 6, and includes a flow chamber 21, a resin recovery valve 23, a waste liquid valve 24, and a nozzle isolation valve 22.

[0061] The flow chamber 21 is connected to the common liquid supply pipe 5. The resin recovery pipe 25 is connected to the flow chamber 21 through the resin recovery valve 23, the waste liquid collection pipe 16 is connected to the flow chamber 21 through the waste liquid valve 24, and the piezoelectric nozzle 6 is connected to the flow chamber 21 through the nozzle isolation valve 22.

[0062] The resin recovery valve 23 is used to control the connection and disconnection between the flow chamber 21 and the resin recovery pipe 25; the waste liquid valve 24 is used to control the connection and disconnection between the flow chamber 21 and the waste liquid collection pipe 16; and the nozzle isolation valve 22 is used to control the connection and disconnection between the flow chamber 21 and the piezoelectric nozzle 6.

[0063] In the resin recovery state, resin recovery valve 23 is open, and waste liquid valve 24 and nozzle isolation valve 22 are closed, allowing the medium supplied by the common supply pipe 5 to enter the resin recovery pipe 25. In the transition mixture discharge state, waste liquid valve 24 is open, and resin recovery valve 23 and nozzle isolation valve 22 are closed, allowing the medium supplied by the common supply pipe 5 to enter the waste liquid collection pipe 16. In the nozzle supply state, nozzle isolation valve 22 is open, and resin recovery valve 23 and waste liquid valve 24 are closed, allowing the medium supplied by the common supply pipe 5 to enter the piezoelectric nozzle 6.

[0064] Preferably, the valve seats of the resin recovery valve 23, waste liquid valve 24 and nozzle isolation valve 22 are centrally located at the periphery of the flow chamber 21, so that the medium in the flow chamber 21 can reach each valve seat through a shorter flow path, thereby reducing the stagnation volume between the flow chamber 21 and each valve seat.

[0065] The valve seat of the nozzle isolation valve 22 is located near the inlet of the piezoelectric nozzle 6. Specifically, the valve seat of the nozzle isolation valve 22 can be located at the liquid inlet end of the inlet connector of the piezoelectric nozzle 6, so that the pipe section length between the actual cut-off position of the nozzle isolation valve 22 and the inlet of the piezoelectric nozzle 6 is relatively short. As a result, during the resin recovery and transition mixture discharge process, the flow path volume downstream of the nozzle isolation valve 22 that cannot participate in the pre-mixing is smaller, reducing the amount of residual mixing medium entering the piezoelectric nozzle 6 after the nozzle isolation valve 22 is opened.

[0066] When the control component 2 switches from connecting to the resin recovery pipe 25 to connecting to the waste liquid collection pipe 16, or from connecting to the waste liquid collection pipe 16 to connecting to the piezoelectric nozzle 6, the controller 7 first pauses the liquid supply, then closes the currently open valve and opens the target valve. After the target valve is fully opened, the liquid supply is resumed, thereby avoiding abnormal pressure rise in the flow chamber 21 when all three outlets are closed at the same time.

[0067] A flow detection element 8 is installed on the cleaning fluid supply pipe 4. The flow detection element 8 is used to detect the real-time flow rate of the cleaning fluid and send the detection result to the controller 7. The flow detection element 8 can be a volumetric flow meter, a turbine flow meter, or a flow sensor.

[0068] The control component 2 also includes a medium detection element 26. The medium detection element 26 is disposed in the flow cavity 21 or in a detection cavity communicating with the flow cavity 21, and is used to detect medium characteristic parameters that can reflect changes in the composition of the flowing medium.

[0069] The media detection element 26 is preferably located in the common flow area at the common inlet end of the resin recovery valve 23, waste liquid valve 24, and nozzle isolation valve 22. The valve seats of the three valves are centrally located around the flow chamber 21, and the media detection element 26 is located adjacent to the three valve seats, so that the flow path between the media detection position and the actual flow path switching position is shorter.

[0070] The medium detection element 26 can detect medium characteristic parameters that characterize changes in the composition of the flowing medium based on the differences in physical properties between the furan resin and the cleaning liquid. The medium detection element 26 can be at least one of the following: optical transmission detection element, optical reflection detection element, refractive index detection element, dielectric parameter detection element, capacitance detection element, viscosity detection element, density detection element, or acoustic parameter detection element.

[0071] In one specific embodiment, the medium detection element 26 is an optical transmission detection element, including a light emitting part and a light receiving part respectively disposed on both sides of the medium flow path. The light emitting part emits detection light into the medium flowing through it, and the light receiving part receives the detection light after it has passed through the medium, and determines the corresponding detection value based on the received light intensity. Since the transmission characteristics of the detection light differ between furan resin, cleaning liquid, and the transition mixture formed by the two, the detection value changes with the composition of the medium as the medium gradually changes from furan resin to cleaning liquid.

[0072] Before the system is put into operation, furan resin and cleaning fluid are flowed through the medium detection element 26 respectively, and the detection values ​​corresponding to the two media are calibrated. The preset resin characteristic range is determined based on the detection value of furan resin and its allowable fluctuation range, and the preset cleaning fluid characteristic range is determined based on the detection value of cleaning fluid and its allowable fluctuation range.

[0073] When the detected value is within the preset resin characteristic range, it is determined that the flowing medium is in a resin state; when the detected value leaves the preset resin characteristic range and has not yet met the preset cleaning liquid determination condition, it is determined that the flowing medium is a transitional mixture formed by resin and cleaning liquid; when the detected value enters the preset cleaning liquid characteristic range and continues for a preset time, it is determined that the flowing medium meets the preset cleaning liquid determination condition.

[0074] The reusable resin referred to in this embodiment refers to the resin segment discharged from the resin recovery pipe 25 when the cumulative delivery volume of the cleaning fluid has not yet reached the preset recovery volume, and the detection value of the medium detection element 26 is still within the preset resin characteristic range, during the process of the cleaning fluid pushing the original resin in the common supply pipe 5. After this resin segment is recovered, it can also be subjected to quality testing based on viscosity, water content, medium characteristics, or storage time, and can be used for subsequent printing after meeting the preset reuse requirements.

[0075] The preset duration is used to eliminate misjudgments caused by fluid fluctuations, bubbles, or local changes in the composition of the medium. The preset duration can be calibrated through experiments based on the sampling frequency of the medium detection element 26, the length of the common liquid supply pipe 5, the flow rate of the cleaning fluid, and the mixing characteristics of the resin and the cleaning fluid.

[0076] The internal volume occupied by the flowing medium during the medium switching process, from the downstream side of the valve seat of the third opening / closing element 15 to the medium detection position of the medium detection element 26, is defined as the effective flow path volume. The effective flow path volume includes the effective valve cavity volume downstream of the valve seat of the third opening / closing element 15, the internal volume of the common liquid supply pipe 5, the internal volume of the connecting joint, and the volume from the inlet of the flow chamber 21 to the medium detection position.

[0077] The effective volume of the flow path can be calculated based on the inner diameter and length of each pipe section, or it can be calibrated after the system is assembled using quantitative filling or liquid replacement methods. The corresponding effective volume of the flow path is pre-stored in controller 7.

[0078] A preset recovery amount is determined based on the effective volume of the flow path. In one specific embodiment, the preset recovery amount satisfies:

[0079]

[0080] in, To preset the recycling amount, The effective volume of the flow path between the downstream side of the valve seat of the third opening / closing element 15 and the medium detection position of the medium detection element 26. A safety reserve volume is provided for the mixing front of the resin and cleaning solution. A safety reserve volume is provided for flow detection errors, valve action errors, and medium detection response errors. From the moment the cleaning supply pipe 4 is connected to the common supply pipe 5, the cumulative delivery volume of the cleaning fluid satisfies:

[0081]

[0082] in, This represents the cumulative volume of cleaning fluid delivered. For the flow detection device at time The real-time volumetric flow rate of the cleaning fluid was detected. The moment when the cleaning supply pipe 4 and the common supply pipe 5 begin to connect. This represents the current cumulative time.

[0083] The cumulative delivery volume begins to be calculated when the cleaning supply pipe 4 and the common supply pipe 5 are connected and the cleaning fluid begins to enter the common supply pipe 5. After the second opening and closing element 12 and the third opening and closing element 15 are opened and the fourth opening and closing element 14 is closed, the controller 7 resets the cumulative delivery volume to zero and starts to accumulate, so that the cumulative delivery volume corresponds to the actual volume of cleaning fluid entering the common supply pipe 5 and pushing the original resin to move.

[0084] When the cumulative delivery of the cleaning fluid reaches the preset recovery amount, or when the detection value of the medium detection element 26 leaves the preset resin characteristic range, the controller 7 controls the system to end resin recovery. The first of the two conditions is met as the recovery termination condition to avoid introducing the transitional mixture into the resin recovery pipe 25.

[0085] During normal printing, the anti-mixing component 1 is in resin supply mode. The first and third opening / closing components 11 and 15 are open, while the second and fourth opening / closing components 12 and 14 are closed. In the control component 2, the printhead isolation valve 22 is open, while the resin recovery valve 23 and waste liquid valve 24 are closed.

[0086] Furan resin enters the anti-mixing component 1 through the resin supply pipe 3, and then sequentially enters the common supply pipe 5 through the first opening and closing element 11, the mixing chamber 13, and the third opening and closing element 15. Finally, it enters the piezoelectric nozzle 6 through the flow chamber 21 and the nozzle isolation valve 22. The piezoelectric nozzle 6 selectively sprays the furan resin onto the predetermined area of ​​the molding sand layer according to the printing control signal.

[0087] Example 2

[0088] like Figure 2 As shown, when the printing task ends, the device enters a long standby state, or the piezoelectric printhead 6 needs to be cleaned, the controller 7 executes the process of switching from resin supply to cleaning fluid supply.

[0089] First, stop the printing drive of the piezoelectric printhead 6, stop or reduce the resin supply, and close the printhead isolation valve 22 to isolate the common supply line 5 from the piezoelectric printhead 6. During subsequent mixing processes, including mixing by the anti-mixing component 1, reusable resin recovery, and discharge of the transition mixture, the printhead isolation valve 22 remains closed.

[0090] Subsequently, the anti-mixing component 1 is controlled to enter the intermediate isolation and mixing-free state. Specifically, the first opening and closing element 11 and the third opening and closing element 15 are closed, the second opening and closing element 12 is kept closed, and the fourth opening and closing element 14 is opened. At this time, the resin supply pipe 3 and the cleaning supply pipe 4 are both isolated from the common supply pipe 5, and the furan resin remaining in the anti-mixing component 1 enters the mixing-free chamber 13 and is discharged through the fourth opening and closing element 14 and the waste liquid collection pipe 16.

[0091] After the residual medium in the mixing chamber 13 is discharged, the fourth opening and closing element 14 is closed. In one specific embodiment, after the fourth opening and closing element 14 is opened, the controller 7 keeps the fourth opening and closing element 14 open for a preset mixing time to ensure that the residual medium in the mixing chamber 13 is fully discharged; after the preset mixing time is reached, the controller 7 closes the fourth opening and closing element 14. The preset mixing time can be predetermined based on the effective volume of the mixing chamber 13 and the flow capacity of the mixing passage.

[0092] After completing the above-mentioned mixing process, connect the cleaning supply pipe 4 to the common supply pipe 5. Open the second and third opening / closing components 12 and 15, open the resin recovery valve 23, and keep the waste liquid valve 24 and nozzle isolation valve 22 closed. After confirming that the second and third opening / closing components 12, 15, and resin recovery valve 23 are in place, start the cleaning fluid supply.

[0093] The cleaning fluid enters the common supply pipe 5, pushing the existing furan resin in the common supply pipe 5 towards the control component 2. From the time the cleaning supply pipe 4 is connected to the common supply pipe 5, the controller 7 determines the cumulative delivery volume of the cleaning fluid based on the detection result of the flow detection element 8.

[0094] The resin in the front section of the public supply pipe 5 that has not yet been significantly mixed with the cleaning fluid enters the resin recovery pipe 25 through the flow chamber 21 and the resin recovery valve 23 to complete the recovery of reusable resin.

[0095] When the cumulative delivery of cleaning fluid reaches the preset recovery amount, or when the detection value of the medium detection element 26 leaves the preset resin characteristic range, the controller 7 determines that the recovery of reusable resin has ended.

[0096] At this time, the controller 7 suspends the supply of cleaning fluid, closes the resin recovery valve 23, and opens the waste liquid valve 24. After the waste liquid valve 24 is fully open, the supply of cleaning fluid is resumed. At this time, the common supply pipe 5 is isolated from the resin recovery pipe 25 and connected to the waste liquid collection pipe 16. Subsequently, the transition mixture that reaches the control component 2 is discharged through the waste liquid valve 24 and the waste liquid collection pipe 16.

[0097] During the discharge of the transition mixture, the medium detection element 26 continuously detects the flowing medium. When the detection value of the medium detection element 26 enters the preset cleaning fluid characteristic range and remains there for a preset duration, the controller 7 determines that the flowing medium meets the preset cleaning fluid judgment conditions.

[0098] Preferably, when there is still a delayed flow path volume between the medium detection element 26 and the valve seat of the waste liquid valve 24 or the nozzle isolation valve 22, the controller 7 continues to keep the waste liquid valve 24 open after the detection value of the medium detection element 26 meets the preset cleaning liquid judgment condition, so that the amount of medium corresponding to the delayed flow path volume enters the waste liquid collection pipe 16, and then performs nozzle liquid supply switching.

[0099] After the transition mixture is discharged, the controller 7 pauses the cleaning fluid supply, closes the waste liquid valve 24, and opens the nozzle isolation valve 22. The cleaning fluid supply is resumed after the nozzle isolation valve 22 is fully open. The cleaning fluid enters the piezoelectric nozzle 6 through the common supply pipe 5, the flow chamber 21, and the nozzle isolation valve 22 to replace the residual furan resin in the internal flow channel, pressure chamber, and near the nozzle orifice of the piezoelectric nozzle 6.

[0100] The cleaning process can be performed according to a preset cleaning time or a preset cleaning fluid delivery volume. In a preferred embodiment, a maintenance cap or waste fluid receiving component is provided below the nozzle surface of the piezoelectric nozzle 6, and the cleaning fluid discharges the residual resin in the piezoelectric nozzle 6 through the nozzle into the maintenance cap or waste fluid receiving component.

[0101] After cleaning is completed, the supply of cleaning fluid can be stopped and the nozzle isolation valve 22 can be closed, so that the cleaning fluid is retained in the piezoelectric nozzle 6, and the system enters the cleaning and moisturizing standby state.

[0102] like Figure 3 As shown, when the system needs to resume printing, first keep the printhead isolation valve 22 closed to keep the common liquid supply pipe 5 isolated from the piezoelectric printhead 6.

[0103] Stop the supply of cleaning fluid, close the second and third opening / closing components 12 and 15, keep the first opening / closing component 11 closed, and open the fourth opening / closing component 14. The cleaning fluid remaining in the anti-mixing assembly 1 enters the mixing chamber 13 and is discharged through the waste liquid collection pipe 16.

[0104] After the residual cleaning fluid is discharged, close the fourth opening and closing element 14, and open the first opening and closing element 11 and the third opening and closing element 15 to connect the resin supply pipe 3 with the common supply pipe 5.

[0105] The controller 7 opens the waste liquid valve 24, keeps the resin recovery valve 23 and the nozzle isolation valve 22 closed, and then begins to deliver furan resin. The resin enters the common supply pipe 5 and pushes the original cleaning liquid in the common supply pipe 5 towards the control component 2. The medium at the contact position between the resin and the cleaning liquid forms a reverse transition mixture, and the cleaning liquid and the reverse transition mixture are discharged sequentially through the flow chamber 21, the waste liquid valve 24, and the waste liquid collection pipe 16.

[0106] The controller 7 determines whether the preset resin determination conditions are met based on the detection result of the medium detection element 26. In one specific embodiment, the preset resin determination conditions include the detection value of the medium detection element 26 entering a preset resin characteristic range and remaining there for a preset duration.

[0107] In another preferred embodiment, the preset resin determination condition further includes: the cumulative amount of medium discharged through the waste liquid collection pipe 16 after the resin supply pipe 3 is connected to the common supply pipe 5 reaches a preset recovery discharge amount. The cumulative medium amount is determined based on the cumulative resin supply flow rate since the resin supply pipe 3 is connected to the common supply pipe 5; the preset recovery discharge amount is determined based on the effective volume of the flow path participating in medium replacement between the downstream side of the valve seat of the third opening and closing element 15 and the valve seat of the waste liquid valve 24. The effective volume of the flow path can be calculated based on the geometric dimensions of the corresponding pipe and valve cavity, or it can be calibrated through a medium replacement test.

[0108] When the cumulative amount of medium reaches the preset recovery discharge amount, and the detection value of the medium detection element 26 enters the preset resin characteristic range and continues for a preset duration, it is determined that the flowing medium meets the preset resin determination condition.

[0109] When the flowing medium meets the preset resin judgment conditions, the controller 7 suspends the resin supply, closes the waste liquid valve 24 and opens the nozzle isolation valve 22. The resin supply is restored after the nozzle isolation valve 22 is fully opened.

[0110] Resin enters the piezoelectric nozzle 6 via the common supply pipe 5, flow chamber 21, and nozzle isolation valve 22 to replace the cleaning fluid retained inside the piezoelectric nozzle 6. Preferably, a preset amount of resin is continued to be supplied while the nozzle face of the piezoelectric nozzle 6 is still aligned with the maintenance cap or waste liquid receiving part, so that the cleaning fluid and reverse transition mixture inside the piezoelectric nozzle 6 are discharged.

[0111] The preset amount is determined based on the effective wetting volume within the piezoelectric nozzle 6 that participates in media replacement. The effective wetting volume is the internal flow path volume occupied by the flowing medium within the piezoelectric nozzle 6 during the media replacement process, including the inlet flow path, internal liquid supply channel, pressure chamber, and flow path volume communicating with the nozzle orifice of the piezoelectric nozzle 6. It can be calculated based on the internal flow path dimensions of the piezoelectric nozzle 6, or it can be calibrated through a media replacement test.

[0112] The above are merely preferred embodiments of the present invention. The specific types of the first opening and closing element 11, the second opening and closing element 12, the third opening and closing element 15, the fourth opening and closing element 14, the resin recovery valve 23, the waste liquid valve 24, and the nozzle isolation valve 22, as well as the detection principles of the flow detection element 8 and the medium detection element 26, can be selected according to the furan resin, cleaning fluid, and piezoelectric nozzle 6 used. As long as the common supply pipe 5 can be isolated and the residual medium in the anti-mixing component 1 can be discharged during the medium switching process, and the reusable resin recovery and transition mixture discharge can be completed sequentially while the piezoelectric nozzle 6 remains isolated, and the cleaning fluid is supplied to the piezoelectric nozzle 6 after the flowing medium meets the preset cleaning fluid judgment conditions, the technical objective of the present invention can be achieved.

Claims

1. A 3D printing inkjet system with media anti-mixing switching and automatic cleaning, comprising a resin supply pipe for providing furan resin, a cleaning supply pipe for providing cleaning fluid, a common supply pipe connected to the resin supply pipe and the cleaning supply pipe, and a piezoelectric printhead connected to the common supply pipe, characterized in that, An anti-mixing component is provided between the resin supply pipe and the cleaning supply pipe and the common supply pipe, and the anti-mixing component is also connected to a waste liquid collection pipe; a control component is also provided between the common supply pipe and the piezoelectric printhead, and the control component is also connected to the resin recovery pipe and the waste liquid collection pipe; the inkjet system also includes a controller that is signal-connected to the anti-mixing component and the control component respectively. The anti-mixing component is used to switch the connection status of the resin supply pipe and the cleaning supply pipe with the common supply pipe. When switching, it is first disconnected from the common supply pipe. After the residual medium in the anti-mixing component is introduced into the waste liquid collection pipe, it is then connected to the common supply pipe. The control component is used to switch the connection state between the common liquid supply pipe and the piezoelectric nozzle. When switching from resin supply to cleaning liquid supply, it is first disconnected from the piezoelectric nozzle, the reusable resin is introduced into the resin recovery pipe, and the transition mixture formed by the resin and the cleaning liquid is introduced into the waste liquid collection pipe. After the flowing medium meets the preset cleaning liquid judgment conditions, it is then connected to the piezoelectric nozzle.

2. The 3D printing inkjet system for media anti-mixing switching and automatic cleaning according to claim 1, characterized in that, The anti-mixing component includes a mixing chamber, a first opening and closing element and a second opening and closing element for controlling the on / off state of the resin supply pipe and the cleaning supply pipe, respectively, and a third opening and closing element for controlling the on / off state of the anti-mixing component and the common supply pipe. The mixing chamber is connected to the waste liquid collection pipe, and a fourth opening and closing element is provided at the connection.

3. The 3D printing inkjet system for media anti-mixing switching and automatic cleaning according to claim 2, characterized in that, The control assembly includes a flow chamber connected to the common liquid supply pipe, and a resin recovery valve, a waste liquid valve, and a nozzle isolation valve for controlling the connection and disconnection between the flow chamber and the resin recovery pipe, the waste liquid collection pipe, and the piezoelectric nozzle, respectively; the valve seat of the nozzle isolation valve is located near the piezoelectric nozzle.

4. The 3D printing inkjet system for media anti-mixing switching and automatic cleaning according to claim 3, characterized in that, The cleaning supply pipe is equipped with a flow detection device, and the control component also includes a medium detection device for detecting the state of the flowing medium. The flow detection device and the medium detection device are signal-connected to the controller.

5. The 3D printing inkjet system for media anti-mixing switching and automatic cleaning according to claim 4, characterized in that, The controller is configured to: determine the cumulative delivery amount of cleaning fluid based on the detection result of the flow detection element, and determine a preset recovery amount based on the effective volume of the flow path between the anti-mixing component and the medium detection element; when the cumulative delivery amount reaches the preset recovery amount, or when the detection value of the medium detection element leaves the preset resin characteristic range, close the resin recovery valve and open the waste liquid valve; when the detection value of the medium detection element enters the preset cleaning fluid characteristic range and remains there for a preset duration, determine that the flowing medium meets the preset cleaning fluid determination condition.

6. The 3D printing inkjet system for media anti-mixing switching and automatic cleaning according to claim 4, characterized in that, The medium detection element is located near the valve seat of the resin recovery valve, the waste liquid valve, and the nozzle isolation valve.

7. A method for media anti-mixing switching and automatic cleaning in a 3D printing inkjet system, characterized in that, The 3D printing inkjet system is the media anti-mixing switching and automatic cleaning 3D printing inkjet system according to any one of claims 1 to 6. When switching from resin supply to cleaning solution supply, the method includes: The control component is used to disconnect the common liquid supply pipe from the piezoelectric nozzle. The anti-mixing component is controlled to disconnect the resin supply pipe and the cleaning supply pipe from the common supply pipe, and the residual medium in the anti-mixing component is introduced into the waste liquid collection pipe, and then the cleaning supply pipe is connected to the common supply pipe. With the common liquid supply pipe and the piezoelectric nozzle kept isolated, the common liquid supply pipe is connected to the resin recovery pipe, and the cleaning fluid pushes the resin in the common liquid supply pipe and introduces the reusable resin into the resin recovery pipe. After the recycling of the reusable resin is completed based on the cumulative delivery volume of the cleaning fluid and the detection results of the flowing medium, the common supply pipe is isolated from the resin recycling pipe and connected to the waste liquid collection pipe, and the transition mixture formed by the resin and the cleaning fluid is introduced into the waste liquid collection pipe. When the detection result of the flowing medium meets the preset cleaning fluid determination conditions, the common liquid supply pipe is isolated from the waste liquid collection pipe and connected to the piezoelectric nozzle to supply cleaning fluid to the piezoelectric nozzle to replace the residual resin in the piezoelectric nozzle.

8. The media anti-mixing switching and automatic cleaning method for a 3D printing inkjet system according to claim 7, characterized in that, The step of determining the end of the recycling of the reusable resin based on the cumulative delivery volume of the cleaning fluid and the detection results of the flowing medium includes: The flow rate of the cleaning fluid is detected by a flow detection device installed on the cleaning fluid supply pipe. From the time the cleaning fluid supply pipe is connected to the common fluid supply pipe, the cumulative delivery amount of the cleaning fluid is determined based on the detection result of the flow detection device. The medium flowing through the control component is detected by a medium detection device installed on the control component. A preset recovery amount is determined based on the effective volume of the flow path between the anti-mixing component and the medium detection element. When the cumulative delivery amount reaches the preset recovery amount, or when the detection value of the medium detection element leaves the preset resin characteristic range, the recovery of the reusable resin is determined to be completed. The preset cleaning fluid determination conditions include: the detection value of the medium detection element enters the preset cleaning fluid characteristic range and remains there for a preset duration.

9. The media anti-mixing switching and automatic cleaning method for a 3D printing inkjet system according to claim 7 or 8, characterized in that, It also includes the step of reverting from the cleaning solution supply to the resin supply: The control component is used to disconnect the common liquid supply pipe from the piezoelectric nozzle. The anti-mixing component is controlled to disconnect the resin supply pipe and the cleaning supply pipe from the common supply pipe, and the residual cleaning liquid in the anti-mixing component is introduced into the waste liquid collection pipe, and then the resin supply pipe is connected to the common supply pipe. With the common liquid supply pipe and the piezoelectric nozzle kept isolated, the common liquid supply pipe is connected to the waste liquid collection pipe, so that the resin pushes the cleaning liquid in the common liquid supply pipe and the reverse transition mixture formed by the resin and the cleaning liquid into the waste liquid collection pipe. When the detection result of the flowing medium enters the preset resin characteristic range and continues for a preset time, the common liquid supply pipe is isolated from the waste liquid collection pipe and connected to the piezoelectric nozzle to supply resin to the piezoelectric nozzle to replace the cleaning fluid in the piezoelectric nozzle.

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