A microdroplet jetting freeform forming system and method

Abstract

This invention discloses a microdroplet jetting freeform forming system and method, comprising a forming module, a piezoelectric ceramic module with a self-sensing unit, and further including data storage, piezoelectric ceramic driving, liquid pressure feedback, data processing, and feedforward control modules. This invention utilizes the self-sensing unit in conjunction with each module to enhance the system's sensing capability, enabling real-time and accurate capture of liquid pressure changes within the guide tube, fine-tuning the droplet formation process, avoiding jetting anomalies, and improving forming stability and reliability. Based on feedforward control, the piezoelectric ceramic motion planning is reprogrammed, including curve morphology, voltage amplitude, and frequency changes. It can also sense nozzle blockage and guide tube rupture, avoiding production interruptions and quality issues, ensuring continuous and stable system operation, and improving forming quality and efficiency.

Description

Technical Field

[0001] This invention relates to the field of microdroplet jetting technology, and more specifically to a microdroplet jetting freeform shaping system and method. Background Technology

[0002] Microdroplet jetting freeform forming is a forming method based on the principle of microdroplet jetting. The forming process is as follows: the liquid in the cavity is ejected from the small holes on the cavity by the action of external force and forms droplets. Under the action of initial velocity and gravity, the droplets fly to the substrate, forming a lattice, pattern or stack and solidifying into a solid.

[0003] Typical microdroplet jetting freeform shaping systems include electric field deflection, valve-controlled, thermal bubble, piezoelectric, electrostatic, and micro-injector types, with the piezoelectric type experiencing the fastest development. A commonly used structure for a pre-piezoelectric microdroplet jetting freeform shaping system is as follows: a tubular piezoelectric ceramic is fitted into the middle of a glass tube or PVDF tube with a pointed nozzle. By applying a trapezoidal voltage across the piezoelectric ceramic, the diameter of the tubular piezoelectric ceramic changes due to the "inverse piezoelectric effect." When the diameter of the piezoelectric ceramic increases, the glass tube or PVDF tube begins to absorb liquid; when the diameter decreases, the liquid is expelled at the nozzle and forms droplets.

[0004] However, a common problem exists in all types of microdroplet jetting freeform systems: due to the lack of monitoring and planning of the droplet jetting process, tail droplets or satellite droplets are unavoidable during the replenishment process after the previous droplet is ejected, and it is difficult to ensure the consistency of the ejected droplets. Structurally, current product designs generally only involve the extrusion of liquid and nozzle structure, without considering feedback elements for the liquid state; in terms of drive, the control voltage curve in current products is generally a simple trapezoidal wave, without a reasonable drive voltage waveform based on the droplet formation process, and lacks drive planning for high-speed systems; in terms of feedback control, current products neither provide feedback on the motion state of the driven object nor utilize the self-sensing technology characteristics of the "positive piezoelectric effect" of piezoelectric ceramics, resulting in functional waste.

[0005] In summary, existing products neither adequately plan the motion state of high-speed systems nor monitor system status through feedback. Furthermore, they neglect the self-sensing function of piezoelectric ceramics as sensors, resulting in resource waste. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a microdroplet jetting freeform shaping system and method.

[0007] This invention discloses a microdroplet jetting freeform shaping system, comprising:

[0008] A forming module, comprising a guide tube and a piezoelectric ceramic module acting on the guide tube, wherein one end of the guide tube is provided with a nozzle; the piezoelectric ceramic module comprises a driving part for extruding and stretching the guide tube, a self-sensing part for monitoring the liquid pressure inside the guide tube, and a low-level part for cooperating with the driving part and the self-sensing part;

[0009] The data storage module is used to store a preset motion response, a threshold for allowing deviation between the actual motion response and the preset motion response, a baseline motion plan and a dynamic motion plan as system excitation, wherein the baseline motion plan is used to initialize the dynamic motion plan;

[0010] A piezoelectric ceramic driving module is used to read the dynamic motion plan in the data storage module, shape it into a voltage curve, amplify it, and then apply it to the driving part and the low-level part.

[0011] A liquid pressure feedback module is used to receive the voltage signal converted by the self-sensing unit, amplify it and perform analog-to-digital conversion; and to determine whether the guide tube is ruptured or the nozzle is blocked based on the voltage signal from the self-sensing unit.

[0012] The data processing module is used to convert the voltage signal after analog-to-digital conversion into an actual motion response, and compare the actual motion response with the preset motion response to determine whether it exceeds the deviation threshold. If it does not exceed the threshold, the original motion plan is followed for excitation; if it exceeds the threshold, a new motion plan is output.

[0013] A feedforward control module performs neural network training based on the new motion plan and the actual motion response to optimize the motion plan and update the dynamic motion plan in the data storage module.

[0014] As a further improvement of the present invention, the piezoelectric ceramic module includes a piezoelectric ceramic tube, which is sleeved on the guide tube;

[0015] The piezoelectric ceramic tube is composed of an inner layer and an outer layer. The inner layer is a low-level electrode, and the first high-level electrode in the middle section of the outer layer is connected to serve as the driving part. The low-level connection point at the end of the outer layer away from the nozzle is connected to the low-level electrode to form the low-level part. The second high-level electrode at the end of the outer layer near or away from the nozzle is connected to serve as the self-sensing part.

[0016] As a further improvement of the present invention, the piezoelectric ceramic module includes a driving piezoelectric ceramic tube and a self-sensing piezoelectric ceramic tube. The driving piezoelectric ceramic tube is sleeved on the end of the guide tube near the nozzle, and the self-sensing piezoelectric ceramic tube is sleeved on the end of the guide tube away from the nozzle.

[0017] Both the driving piezoelectric ceramic tube and the self-sensing piezoelectric ceramic tube are composed of an inner layer and an outer layer. The inner layer of both the driving piezoelectric ceramic tube and the self-sensing piezoelectric ceramic tube is a low-level electrode. The outer layer of the driving piezoelectric ceramic tube is composed of a low-level connection point and a first high-level electrode connection point. The outer layer of the self-sensing piezoelectric ceramic tube is composed of a low-level connection point and a second high-level electrode connection point. The first high-level electrode connection point constitutes the driving part, and the second high-level electrode connection point constitutes the self-sensing part.

[0018] As a further improvement of the present invention, the distance from the first high-level electrode wiring to the outer end face of the nozzle is the same as the distance from the first high-level electrode wiring to the second high-level electrode wiring.

[0019] As a further improvement of the present invention, the piezoelectric ceramic driving module includes:

[0020] A curve shaping unit is used to shape the dynamic motion plan read from the data storage module into a voltage curve;

[0021] The first voltage amplification unit is used to amplify the shaped voltage curve;

[0022] A voltage regulator unit is used to regulate the amplified voltage curve to form a driving voltage. The high level of the driving voltage is transmitted to the driving section, and the low level of the driving voltage is transmitted to the low level section.

[0023] As a further improvement of the present invention, the liquid pressure feedback module includes:

[0024] The second voltage amplification unit is used to amplify the voltage signal converted by the self-sensing unit;

[0025] The A / D conversion unit is used to convert the amplified voltage signal into a digital signal;

[0026] The signal processing and equivalent viscosity calculation unit is used to process the amplified voltage signal to obtain the equivalent viscosity value used to determine whether the guide tube is broken or the nozzle is blocked.

[0027] As a further improvement of the present invention, when the equivalent viscosity value suddenly increases, it is determined that the nozzle is blocked; when the equivalent viscosity value suddenly decreases, it is determined that the guide tube is ruptured or leaking.

[0028] The present invention also discloses a control method for a microdroplet jetting freeform forming device, which is applied to the above-mentioned microdroplet jetting freeform forming system, comprising:

[0029] The droplet ejection control process includes:

[0030] The piezoelectric ceramic drive module reads the dynamic motion plan stored in the data storage module and shapes it to form a voltage curve;

[0031] The voltage curve is amplified and regulated to form a piezoelectric ceramic driving voltage. The high level of the piezoelectric ceramic driving voltage is transmitted to the driving part of the piezoelectric ceramic module, and the low level is transmitted to the low level part of the piezoelectric ceramic module.

[0032] Based on the inverse piezoelectric effect, the piezoelectric ceramic module acts on the guide tube to cause the liquid in the guide tube to be ejected through the nozzle to form droplets;

[0033] The motion response deviation control process includes:

[0034] Based on the positive piezoelectric effect, the self-sensing part of the piezoelectric ceramic module converts the liquid fluctuations in the guide tube into voltage signals;

[0035] The liquid pressure feedback module amplifies and performs analog-to-digital conversion on the converted voltage signal, and then transmits the converted digital signal to the data processing module.

[0036] The data processing module converts the digital signal into an actual motion response related to the pressure fluctuations inside the guide tube, and retrieves the preset motion response and deviation threshold from the data storage module; it compares the actual motion response with the preset motion response and calculates the response deviation to determine whether the response deviation exceeds the deviation threshold; if it does not exceed the threshold, the system excites the system according to the dynamic motion plan of the original motion plan; if it exceeds the threshold, the feedforward control module is triggered.

[0037] The feedforward control module uses the collected actual motion response and dynamic motion plan as training samples to perform feedforward control training. After training, it reads the preset motion response in the data storage module, optimizes it based on the neural network, and updates the dynamic motion plan in the data storage module based on the optimized voltage curve.

[0038] As a further improvement of the present invention, a guide tube status detection process is also included, which includes:

[0039] Based on the positive piezoelectric effect, the self-sensing part of the piezoelectric ceramic module converts the liquid fluctuations in the guide tube into voltage signals;

[0040] The liquid pressure feedback module amplifies the converted voltage signal, rectifies and integrates the decay waveform of the pressure fluctuation in each cycle, and calculates its average value as the equivalent viscosity value.

[0041] When the equivalent viscosity value suddenly increases, it is determined that the nozzle is blocked; when the equivalent viscosity value suddenly decreases, it is determined that the guide tube is ruptured or leaking.

[0042] As a further improvement of the present invention, in the initial state, the dynamic motion planning in the data storage module is consistent with the baseline motion planning.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] This invention adds a self-sensing unit to the piezoelectric ceramic module in its structure, and incorporates a data storage module, a piezoelectric ceramic driving module, a liquid pressure feedback module, a data processing module, and a feedforward control module in its control system. This organically integrates the self-sensing unit with each module, fully utilizing the piezoelectric ceramic self-sensing as a sensing element. This significantly enhances the system's sensing capability, enabling it to capture subtle changes in liquid pressure within the guide tube in real time and with precision. This allows for more precise control of the droplet formation process, effectively avoiding abnormal droplet ejection due to missing or inaccurate information, thereby improving the stability and reliability of the entire microdroplet ejection and free-formation process.

[0045] This invention reprograms the motion planning of piezoelectric ceramics based on feedforward control, encompassing multiple key dimensions such as curve morphology adjustment, voltage amplitude variation, and frequency variation. Regarding curve morphology adjustment, the shape of the voltage curve can be optimized based on real-time feedback information to better meet the ideal droplet ejection requirements. Voltage amplitude variation precisely controls the intensity of the piezoelectric ceramic's action on the guide tube, ensuring the liquid is subjected to just the right amount of compression and stretching. Frequency variation adjustment further enhances the control over the droplet ejection rhythm, enabling droplets to be ejected stably at a predetermined frequency. Through these comprehensive reprogramming methods, the system can adapt to different working conditions and environmental changes, maintaining a consistently efficient and stable microdroplet ejection state, significantly improving forming quality and efficiency, and effectively avoiding the formation of stray droplets such as tail droplets and satellite droplets.

[0046] This invention, by incorporating a self-sensing unit, enables the self-sensing of whether the nozzle is clogged or the guide tube is broken, thus avoiding production interruptions and product quality issues caused by nozzle clogging or guide tube breakage, and ensuring the continuous and stable operation of the microdroplet jet free-forming system. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the forming module structure of the microdroplet jetting freeform forming system disclosed in the first embodiment of the present invention;

[0048] Figure 2 This is a structural diagram of the guide tube of the microdroplet jetting freeform shaping system disclosed in the second embodiment of the present invention;

[0049] Figure 3 This is a structural diagram of the piezoelectric ceramic module of the microdroplet jetting freeform system disclosed in one embodiment of the present invention;

[0050] Figure 4 This is a system composition and flowchart of a microdroplet jetting freeform shaping system disclosed in one embodiment of the present invention;

[0051] Figure 5 This is a schematic diagram of the forming module structure of the microdroplet jetting freeform forming system disclosed in the second embodiment of the present invention;

[0052] Figure 6 This is a side sectional view of the forming module of the microdroplet jetting freeform forming system disclosed in the second embodiment of the present invention;

[0053] Figure 7 This is a side sectional view of the guide tube of the microdroplet jetting freeform shaping system disclosed in the second embodiment of the present invention;

[0054] Figure 8 This is a structural diagram of the driving piezoelectric ceramic tube of the microdroplet jetting freeform system disclosed in the second embodiment of the present invention;

[0055] Figure 9 This is a structural diagram of the self-sensing piezoelectric ceramic tube of the microdroplet jetting freeform system disclosed in the second embodiment of the present invention;

[0056] Figure 10 The system composition and flowchart of the microdroplet jetting freeform shaping system disclosed in the second embodiment of the present invention are shown below;

[0057] Figure 11 This is a schematic diagram of the voltage curve of the microdroplet jetting freeform shaping system disclosed in this invention.

[0058] In the picture:

[0059] 1. Guide tube; 101. Guide tube body; 102. Nozzle; 2. Piezoelectric ceramic tube; 3. Drive piezoelectric ceramic tube; 4. Self-sensing piezoelectric ceramic tube; 5. Data storage module; 6. Piezoelectric ceramic drive module; 7. Liquid pressure feedback module; 8. Data processing module; 9. Feedforward control module;

[0060] 201, 301, 401, low-level electrode;

[0061] 202, 302, 402, low-level connection points;

[0062] 203, 303, Drive Unit;

[0063] 204, 403, Self-sensing unit. Detailed Implementation

[0064] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0065] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0066] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0067] The present invention will now be described in further detail with reference to the accompanying drawings:

[0068] like Figure 1-10 As shown, a microdroplet jetting freeform forming system according to the present invention includes a forming module, a data storage module 5, a piezoelectric ceramic driving module 6, a liquid pressure feedback module 7, a data processing module 8, and a feedforward control module 9. Specifically:

[0069] The forming module includes a guide tube 1 and a piezoelectric ceramic module acting on the guide tube 1. The guide tube 1 includes a guide tube body 101 and a nozzle 102 disposed at one end of the guide tube body 101. The cross-section of the guide tube body 101 is circular, but it can also be any other shape with a hole in the middle, such as a rectangular ring. The function of the guide tube body 101 is to guide and compress the liquid inside the tube; the nozzle 102 can be a conical hole or a straight hole. Its function is that when the liquid inside the glass tube body is regularly compressed, the liquid can be ejected through the nozzle and form droplets. The piezoelectric ceramic module includes a drive unit for compressing and stretching the guide tube 1, a self-sensing unit for monitoring the liquid pressure inside the guide tube 1, and a low-level unit for cooperating with the drive unit and the self-sensing unit.

[0070] The data storage module 5 stores a preset motion response R0 related to pressure fluctuations within the guide tube 1, a deviation threshold H between the actual motion response R1 and the preset motion response R0, a baseline motion plan M0 obtained from motion planning based on high-speed system dynamics, and a dynamic motion plan M1 as the system excitation. Under initialization conditions, M0 = M1. When the system adjusts its own excitation, the motion plan M1 is refreshed. The baseline motion plan M0, the preset motion response R0, and the deviation threshold H remain unchanged during excitation adjustment and can only be set externally. When the system is reset, M1 is refreshed to be the same as M0. In this invention, the preset motion response R0 is an N×2 matrix, with the first column being time and the second column being the pressure value; the actual motion response R1 is an N×2 matrix, with the first column being time and the second column being the pressure value after processing the voltage value returned by the self-sensing unit; both the baseline motion plan M0 and the dynamic motion plan M1 are normalized arrays (minimum value is 0, maximum value is 1).

[0071] The piezoelectric ceramic driving module 6 includes a curve shaping unit, a first voltage amplification unit, and a voltage regulation unit. The curve shaping unit shapes the dynamic motion plan read from the data storage module into a voltage curve. For example, assuming the current operation requires 100Hz (one cycle is 0.01s), and the maximum voltage across the piezoelectric ceramic is selected as 90V, then the horizontal axis of the dynamic motion plan M1 is multiplied by a period coefficient of 0.01s, and the vertical axis is multiplied by an amplification factor of 90V. The curve showing the voltage required to be applied to the high-level electrode of the piezoelectric ceramic driving unit over time is as follows: Figure 11 As shown; the first voltage amplification unit is used to amplify the shaped voltage curve; the voltage regulation unit is used to regulate the amplified voltage curve to form a driving voltage, and the high level of the driving voltage is transmitted to the driving part; the low level of the driving voltage is transmitted to the low level part.

[0072] The liquid pressure feedback module 7 includes a second voltage amplification unit, an A / D conversion unit, and a signal processing and equivalent viscosity calculation unit. The second voltage amplification unit amplifies the voltage signal converted by the self-sensing part; the A / D conversion unit converts the amplified voltage signal into a digital signal and transmits it to the data processing module 8; the signal processing and equivalent viscosity calculation unit processes the amplified voltage signal to obtain the equivalent viscosity value used to determine whether the guide tube 1 is ruptured or the nozzle 102 is blocked. In actual calculations, based on the self-sensing technology of piezoelectric ceramics, the working status of the microdroplet jet free-forming system can be monitored. The self-sensing ceramic tube and its covered section of the guide tube 1, along with the fluid, are equivalently considered as a Newtonian fluid, and its vibration attenuation constant is:

[0073]

[0074] Where η is the viscosity, ρ is the fluid density, and k is a proportionality constant.

[0075] The attenuation envelope is:

[0076]

[0077] Envelope area:

[0078]

[0079] The product of viscosity and density:

[0080]

[0081] In the detection circuit, the attenuation waveform is amplified, rectified, integrated, and its average value is the product of viscosity and density (referred to as the equivalent viscosity value).

[0082] The data processing module 8 is used to convert the voltage signal sent by the liquid pressure feedback module 7 into the actual motion response R1, and compare the actual motion response R1 with the preset motion response R0 to determine whether the deviation threshold H is exceeded. If it is not exceeded, the excitation is carried out according to the original motion plan. If it is exceeded, the feedforward control module is triggered to quantitatively collect the actual motion response R1 and optimize and refresh the motion plan M1.

[0083] The feedforward control module 9, triggered by the data processing module 8, reads the current motion plan and collects a quantitative amount of actual motion response R1 through the data processing module 8. After training both using a neural network, the module optimizes the motion plan and sends it to the data storage module to update the dynamic motion plan M1.

[0084] Example 1

[0085] like Figure 1-4As shown, the microdroplet jetting freeform forming system provided in the first embodiment of the present invention has a forming device consisting of a guide tube 1 and a piezoelectric ceramic tube 2. The guide tube 1 is a glass tube and includes a guide tube body 101 and a nozzle 102. The piezoelectric ceramic tube 2 is provided in one unit and is sleeved on the glass tube. The end of the glass tube is provided with a nozzle 102.

[0086] like Figure 3 As shown, in the above embodiment, preferably, the piezoelectric ceramic tube 2 is composed of an inner layer and an outer layer. The inner layer is entirely a low-level electrode 201; the first high-level electrode in the middle section of the outer layer is connected as a driving part 203; the driving part 203, in cooperation with the low-level electrode 201, squeezes and stretches the guide tube body 101 through the inverse piezoelectric effect and indirectly affects the liquid inside the tube, causing the liquid to generate droplets at the nozzle 102. A low-level connection point 202 is provided at the end of the outer layer away from the nozzle 102, and the low-level connection point 202 is connected to the low-level electrode 201 to form a low-level part; when wiring, in order to more conveniently apply a low level to the inside of the piezoelectric ceramic, the low-level lead is connected to the low-level connection point 202; the second high-level electrode at the end of the outer layer near or away from the nozzle 102 is connected as a self-sensing part 204. When working in conjunction with the low-level electrode 201, the self-sensing unit 204 monitors the liquid pressure inside the guide tube body 101 based on the positive piezoelectric effect and converts its state into a voltage signal, which is then transmitted to the liquid pressure feedback module 7.

[0087] like Figure 4 As shown, in the above embodiments, preferably, the control method of the microdroplet jetting freeform shaping device of this embodiment includes:

[0088] The droplet ejection control process includes:

[0089] 1) After the microdroplet jet free forming device is started, the piezoelectric ceramic drive module 6 reads the dynamic motion plan M1 stored in the data storage module 5, and shapes it to form a voltage curve of voltage change over time.

[0090] 2) After the voltage curve is amplified and regulated by the first voltage amplification unit and the voltage regulation unit, a piezoelectric ceramic driving voltage is formed. The high level of this driving voltage is transmitted to the driving part 203 on the outer layer of the piezoelectric ceramic tube 2; the low level of the driving voltage is transmitted to the low level connection point 202 on the outer layer of the piezoelectric ceramic tube 2.

[0091] 3) Based on the inverse piezoelectric effect, the radius of the driving part 203 on the piezoelectric ceramic tube 2 changes according to the voltage magnitude. This change acts on the guide tube 1 and indirectly causes the liquid pressure inside the guide tube 1 to change in an orderly manner according to a predetermined state.

[0092] 4) Under pressure, the liquid is ejected from nozzle 102 and forms droplets.

[0093] The motion response deviation control process includes:

[0094] 1) Based on the positive piezoelectric effect, the self-sensing part 204 on the piezoelectric ceramic tube 2 converts the liquid fluctuation in the guide tube 1 into a voltage signal;

[0095] 2) The converted voltage signal is transmitted to the liquid pressure feedback module 7 and amplified, and then converted into a digital signal by the liquid pressure feedback module 7 and transmitted to the data processing module 8 in real time;

[0096] 3) The data processing module 8 converts the amplified voltage signal into an actual motion response R1 related to the pressure fluctuation inside the pipe; after retrieving the preset motion response R0 and the deviation threshold H from the data storage module 5, it compares the actual motion response R1 with the preset motion response R0, solves the response deviation ΔR = |R1 - R0|, and determines whether the response deviation ΔR exceeds the deviation threshold H.

[0097] If the deviation does not exceed the deviation threshold H, the system will be excited according to the original motion plan; if the deviation exceeds the deviation threshold H, the feedforward control module 9 will be triggered.

[0098] 4) After the feedforward control module 9 is triggered, the system triggers an alarm for abnormal pressure fluctuation and reports the fault; at the same time, the system starts voltage curve adjustment. The feedforward control module 9 uses the recently collected actual motion response R1 and dynamic motion planning M1 as training samples to perform feedforward control training. After the training is completed, the preset motion response R0 is read and the voltage curve is optimized based on the neural network.

[0099] 5) The system pauses and updates the original dynamic motion plan M1 in the data storage module 5 with the optimized voltage curve. After the replacement is completed, the system continues to execute the droplet injection control process.

[0100] During this process, the self-sensing part 204 on the piezoelectric ceramic tube 2 monitors the pressure fluctuations inside the guide tube body 101 in real time.

[0101] The status detection process for guide tube 1 includes:

[0102] 1) Based on the positive piezoelectric effect, the self-sensing part 204 on the piezoelectric ceramic tube 2 converts the liquid fluctuation in the guide tube 1 into a voltage signal;

[0103] 2) The converted voltage signal is transmitted to the liquid pressure feedback module 7 and amplified. During the attenuation period of each cycle pressure fluctuation, the amplified attenuation waveform is rectified and integrated, and its average value is used as the equivalent viscosity.

[0104] When the equivalent viscosity value suddenly increases, it is determined that the nozzle 102 is blocked; when the equivalent viscosity value suddenly decreases, it is determined that the guide tube body 101 is ruptured or leaking.

[0105] Example 2

[0106] like Figure 5-10 As shown, the microdroplet jetting freeform forming system provided according to the second embodiment of the present invention has a forming device consisting of a guide tube 1, a driving piezoelectric ceramic tube 3, and a self-sensing piezoelectric ceramic tube 4. The guide tube 1 is a glass tube and includes a guide tube body 101 and a nozzle 102. The driving piezoelectric ceramic tube is sleeved on the end of the guide tube 1 near the nozzle 102, and the self-sensing piezoelectric ceramic tube is sleeved on the end of the guide tube 1 away from the nozzle 102.

[0107] like Figure 8 As shown, in the above embodiment, preferably, the driving piezoelectric ceramic tube 3 consists of an inner layer and an outer layer. The inner layer is entirely composed of a low-level electrode 301, and the outer layer consists of a low-level connection point 302 and a driving part 303. The driving part 303 is formed by a first high-level electrode connection provided on the outer layer of the driving piezoelectric ceramic tube 3. In cooperation with the low-level electrode 301, the driving part 303 squeezes and stretches the guide tube body 101 through the inverse piezoelectric effect, indirectly affecting the liquid inside the tube, and causing the liquid to generate droplets at the nozzle 102.

[0108] like Figure 9 As shown, in the above embodiment, preferably, the self-sensing piezoelectric ceramic tube 4 consists of an inner layer and an outer layer. The inner layer is entirely composed of a low-level electrode 401, and the outer layer consists of a low-level connection point 402 and a self-sensing part 403. The self-sensing part 403 is formed by connecting a second high-level electrode to the outer layer of the self-sensing piezoelectric ceramic tube 4. In conjunction with the low-level electrode 401, the self-sensing part 403 monitors the liquid pressure within the guide tube body 101 based on the positive piezoelectric effect and converts its state into a voltage signal, which is then transmitted to the liquid pressure feedback module 7.

[0109] In the above embodiment, preferably, after assembly, the distance from the length center of the drive unit 303 to the outer end face of the nozzle 102 is L1, and the distance from the length center of the drive unit 303 to the length center of the self-sensing unit 403 is L2. In this embodiment, L1 = L2, and based on symmetry, the pressure fluctuation at the length center of the self-sensing unit 403 is considered to be consistent with the pressure fluctuation at the outer end face of the nozzle 102, thereby achieving indirect measurement and monitoring.

[0110] In the above embodiments, the same self-sensing part as in Embodiment 1 can also be retained on the driving piezoelectric ceramic tube 3, and the pressure fluctuation of the outer end face of the nozzle 102 can be calculated by the fluctuation delay and position of each sensing part.

[0111] like Figure 10 As shown, in the above embodiments, preferably, the control method of the microdroplet jetting freeform shaping device of this embodiment includes:

[0112] The droplet ejection control process includes:

[0113] 1) After the microdroplet jet free forming device is started, the piezoelectric ceramic drive module 6 reads the dynamic motion plan M1 stored in the data storage module 5, and shapes it to form a voltage curve of voltage change over time.

[0114] 2) After the voltage curve is amplified and regulated by the first voltage amplification unit and the voltage regulation unit, a piezoelectric ceramic driving voltage is formed. The high level of this driving voltage is transmitted to the driving part 303 of the outer layer of the driving piezoelectric ceramic tube 3; the low level of the driving voltage is transmitted to the low level connection point 302 of the outer layer of the driving piezoelectric ceramic tube 3.

[0115] 3) Based on the inverse piezoelectric effect, the radius of the driving part 303 of the outer layer of the piezoelectric ceramic tube 3 changes according to the voltage. This change acts on the guide tube 1 and indirectly causes the liquid pressure inside the guide tube 1 to change in an orderly manner according to a predetermined state.

[0116] 4) Under pressure, the liquid is ejected from nozzle 102 and forms droplets.

[0117] The motion response deviation control process includes:

[0118] 1) Based on the positive piezoelectric effect, the self-sensing part 403 on the self-sensing piezoelectric ceramic tube 4 converts the liquid fluctuation in the guide tube 1 into a voltage signal;

[0119] 2) The converted voltage signal is transmitted to the liquid pressure feedback module 7 and amplified, and then converted into a digital signal by the liquid pressure feedback module 7 and transmitted to the data processing module 8 in real time;

[0120] 3) The data processing module 8 converts the amplified voltage signal into an actual motion response R1 related to the pressure fluctuation inside the pipe; after retrieving the preset motion response R0 and the deviation threshold H from the data storage module 5, it compares the actual motion response R1 with the preset motion response R0, solves the response deviation ΔR = |R1 - R0|, and determines whether the response deviation ΔR exceeds the deviation threshold H.

[0121] If the deviation does not exceed the deviation threshold H, the system will be excited according to the original motion plan; if the deviation exceeds the deviation threshold H, the feedforward control module 9 will be triggered.

[0122] 4) After the feedforward control module 9 is triggered, the system triggers an alarm for abnormal pressure fluctuation and reports the fault; at the same time, the system starts voltage curve adjustment. The feedforward control module 9 uses the recently collected actual motion response R1 and dynamic motion planning M1 as training samples to perform feedforward control training. After the training is completed, the preset motion response R0 is read and the voltage curve is optimized based on the neural network.

[0123] 5) The system pauses and updates the original dynamic motion plan M1 in the data storage module 5 with the optimized voltage curve. After the replacement is completed, the system continues to execute the droplet injection control process.

[0124] During this process, the self-sensing part 403 on the self-sensing piezoelectric ceramic tube 4 monitors the pressure fluctuations in the guide tube body 101 in real time.

[0125] The status detection process for guide tube 1 includes:

[0126] 1) Based on the positive piezoelectric effect, the self-sensing part 403 on the self-sensing piezoelectric ceramic tube 4 converts the liquid fluctuation in the guide tube 1 into a voltage signal;

[0127] 2) The converted voltage signal is transmitted to the liquid pressure feedback module 7 and amplified. During the attenuation period of each cycle pressure fluctuation, the amplified attenuation waveform is rectified and integrated, and its average value is used as the equivalent viscosity.

[0128] When the equivalent viscosity value suddenly increases, it is determined that the nozzle 102 is blocked; when the equivalent viscosity value suddenly decreases, it is determined that the guide tube body 101 is ruptured or leaking.

[0129] The beneficial effects of this invention are as follows:

[0130] This invention adds a self-sensing unit to the piezoelectric ceramic module in its structure, and adds a data storage module 5, a piezoelectric ceramic driving module 6, a liquid pressure feedback module 7, a data processing module 8, and a feedforward control module 9 in its control system. This organically integrates the self-sensing unit with each module, fully utilizing the piezoelectric ceramic self-sensing as a sensing element, greatly enhancing the system's sensing capability. This allows the system to capture subtle changes in liquid pressure within the guide tube in real time and with precision, enabling more precise control of the droplet formation process. It effectively avoids abnormal droplet ejection caused by missing or inaccurate information, thereby improving the stability and reliability of the entire microdroplet ejection free-formation process.

[0131] This invention reprograms the motion planning of piezoelectric ceramics based on feedforward control, encompassing multiple key dimensions such as curve morphology adjustment, voltage amplitude variation, and frequency variation. Regarding curve morphology adjustment, the shape of the voltage curve can be optimized based on real-time feedback information to better meet the ideal droplet ejection requirements. Voltage amplitude variation precisely controls the intensity of the piezoelectric ceramic's action on the guide tube, ensuring the liquid is subjected to just the right amount of compression and stretching. Frequency variation adjustment further enhances the control over the droplet ejection rhythm, enabling droplets to be ejected stably at a predetermined frequency. Through these comprehensive reprogramming methods, the system can adapt to different working conditions and environmental changes, maintaining a consistently efficient and stable microdroplet ejection state, significantly improving forming quality and efficiency, and effectively avoiding the formation of stray droplets such as tail droplets and satellite droplets.

[0132] This invention, by setting a self-sensing unit, realizes the self-sensing of whether the nozzle 102 is blocked and whether the guide tube 1 is broken, avoiding production interruptions and product quality problems caused by nozzle 102 blockage or guide tube 1 breakage, and ensuring the continuous and stable operation of the microdroplet jet free forming system.

[0133] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A microdroplet jetting freeform shaping system, characterized in that, include: A forming module, comprising a guide tube and a piezoelectric ceramic module acting on the guide tube, wherein one end of the guide tube is provided with a nozzle; the piezoelectric ceramic module comprises a driving part for extruding and stretching the guide tube, a self-sensing part for monitoring the liquid pressure inside the guide tube, and a low-level part for cooperating with the driving part and the self-sensing part; The data storage module is used to store a preset motion response, a threshold for allowing deviation between the actual motion response and the preset motion response, a baseline motion plan and a dynamic motion plan as system excitation, wherein the baseline motion plan is used to initialize the dynamic motion plan; A piezoelectric ceramic driving module is used to read the dynamic motion plan in the data storage module, shape it into a voltage curve, amplify it, and then apply it to the driving part and the low-level part. A liquid pressure feedback module is used to receive the voltage signal converted by the self-sensing unit, amplify it and perform analog-to-digital conversion; and to determine whether the guide tube is ruptured or the nozzle is blocked based on the voltage signal from the self-sensing unit. The data processing module is used to convert the voltage signal after analog-to-digital conversion into an actual motion response, and compare the actual motion response with the preset motion response to determine whether it exceeds the deviation threshold. If it does not exceed the threshold, the original motion plan is followed for excitation; if it exceeds the threshold, a new motion plan is output. A feedforward control module performs neural network training based on the new motion plan and the actual motion response to optimize the motion plan and update the dynamic motion plan in the data storage module.

2. The microdroplet jetting freeform shaping system according to claim 1, characterized in that, The piezoelectric ceramic module includes a piezoelectric ceramic tube, which is sleeved on the guide tube; The piezoelectric ceramic tube is composed of an inner layer and an outer layer. The inner layer is a low-level electrode, and the first high-level electrode in the middle section of the outer layer is connected to serve as the driving part. The low-level connection point at the end of the outer layer away from the nozzle is connected to the low-level electrode to form the low-level part. The second high-level electrode at the end of the outer layer near or away from the nozzle is connected to serve as the self-sensing part.

3. The microdroplet jetting freeform shaping system according to claim 1, characterized in that, The piezoelectric ceramic module includes a driving piezoelectric ceramic tube and a self-sensing piezoelectric ceramic tube. The driving piezoelectric ceramic tube is sleeved on the end of the guide tube near the nozzle, and the self-sensing piezoelectric ceramic tube is sleeved on the end of the guide tube away from the nozzle. Both the driving piezoelectric ceramic tube and the self-sensing piezoelectric ceramic tube are composed of an inner layer and an outer layer. The inner layer of both the driving piezoelectric ceramic tube and the self-sensing piezoelectric ceramic tube is a low-level electrode. The outer layer of the driving piezoelectric ceramic tube is composed of a low-level connection point and a first high-level electrode connection point. The outer layer of the self-sensing piezoelectric ceramic tube is composed of a low-level connection point and a second high-level electrode connection point. The first high-level electrode connection point constitutes the driving part, and the second high-level electrode connection point constitutes the self-sensing part.

4. The microdroplet jetting freeform shaping system according to claim 3, characterized in that, The distance from the first high-level electrode wiring to the outer end face of the nozzle is the same as the distance from the first high-level electrode wiring to the second high-level electrode wiring.

5. The microdroplet jetting freeform shaping system according to claim 1, characterized in that, The piezoelectric ceramic driving module includes: A curve shaping unit is used to shape the dynamic motion plan read from the data storage module into a voltage curve; The first voltage amplification unit is used to amplify the shaped voltage curve; A voltage regulator unit is used to regulate the amplified voltage curve to form a driving voltage. The high level of the driving voltage is transmitted to the driving section, and the low level of the driving voltage is transmitted to the low level section.

6. The microdroplet jetting freeform shaping system according to claim 1, characterized in that, The liquid pressure feedback module includes: The second voltage amplification unit is used to amplify the voltage signal converted by the self-sensing unit; The A / D conversion unit is used to convert the amplified voltage signal into a digital signal; The signal processing and equivalent viscosity calculation unit is used to process the amplified voltage signal to obtain the equivalent viscosity value used to determine whether the guide tube is broken or the nozzle is blocked.

7. The microdroplet jetting freeform shaping system according to claim 6, characterized in that, When the equivalent viscosity value suddenly increases, it is determined that the nozzle is blocked; when the equivalent viscosity value suddenly decreases, it is determined that the guide tube is ruptured or leaking.

8. A control method for a microdroplet jetting freeform forming device, applied to the microdroplet jetting freeform forming system according to any one of claims 1-7, characterized in that, include: The droplet ejection control process includes: The piezoelectric ceramic drive module reads the dynamic motion plan stored in the data storage module and shapes it to form a voltage curve; The voltage curve is amplified and regulated to form a piezoelectric ceramic driving voltage. The high level of the piezoelectric ceramic driving voltage is transmitted to the driving part of the piezoelectric ceramic module, and the low level is transmitted to the low level part of the piezoelectric ceramic module. Based on the inverse piezoelectric effect, the piezoelectric ceramic module acts on the guide tube to cause the liquid in the guide tube to be ejected through the nozzle to form droplets; The motion response deviation control process includes: Based on the positive piezoelectric effect, the self-sensing part of the piezoelectric ceramic module converts the liquid fluctuations in the guide tube into voltage signals; The liquid pressure feedback module amplifies and performs analog-to-digital conversion on the converted voltage signal, and then transmits the converted digital signal to the data processing module. The data processing module converts the digital signal into an actual motion response related to the pressure fluctuations inside the guide tube, and retrieves the preset motion response and deviation threshold from the data storage module; it compares the actual motion response with the preset motion response and calculates the response deviation to determine whether the response deviation exceeds the deviation threshold; if it does not exceed the threshold, the system excites the system according to the dynamic motion plan of the original motion plan; if it exceeds the threshold, the feedforward control module is triggered. The feedforward control module uses the collected actual motion response and dynamic motion plan as training samples to perform feedforward control training. After training, it reads the preset motion response in the data storage module, optimizes it based on the neural network, and updates the dynamic motion plan in the data storage module based on the optimized voltage curve.

9. The control method according to claim 8, characterized in that, It also includes a guide tube status detection process, which includes: Based on the positive piezoelectric effect, the self-sensing part of the piezoelectric ceramic module converts the liquid fluctuations in the guide tube into voltage signals; The liquid pressure feedback module amplifies the converted voltage signal, rectifies and integrates the decay waveform of the pressure fluctuation in each cycle, and calculates its average value as the equivalent viscosity value. When the equivalent viscosity value suddenly increases, it is determined that the nozzle is blocked; when the equivalent viscosity value suddenly decreases, it is determined that the guide tube is ruptured or leaking.

10. The control method according to claim 8, characterized in that, In the initial state, the dynamic motion planning in the data storage module is consistent with the baseline motion planning.

Images