Micro-droplet spraying free forming system and method

Abstract

The system comprises a forming module, a piezoelectric ceramic module in the forming module comprises a self-sensing part, and the system further comprises a data storage module, a piezoelectric ceramic driving module, a liquid pressure feedback module, a data processing module and a feedforward control module. The self-sensing part is matched with all the modules, the sensing capacity of the system is improved, the liquid pressure change in the guide pipe can be accurately captured in real time, the liquid drop forming process can be finely regulated and controlled, spraying abnormity is avoided, and the forming stability and reliability are improved. And re-planning motion planning of the piezoelectric ceramic based on feedforward control, wherein the motion planning comprises curve form, voltage amplitude and frequency change. And the conditions of nozzle blockage and guide pipe breakage can be sensed, production interruption and quality problems are avoided, continuous and stable operation of the system is guaranteed, and the forming quality and efficiency are improved.

Description

Technical Field

[0001] The present invention relates to the field of micro-droplet injection technology, and in particular to a micro-droplet injection free-forming system and method. Background Art

[0002] Droplet jet free forming is a forming method based on the principle of droplet jetting. The forming process is as follows: the liquid in the cavity is ejected from the small holes on the cavity through the action of external force to form droplets. The droplets fly to the substrate under the action of initial velocity and gravity to form a dot matrix, pattern or stack and solidify into a solid.

[0003] Typical droplet ejection free-forming systems include electric field deflection type, valve control type, thermal bubble type, piezoelectric type, electrostatic type and micro-injector type, among which the piezoelectric type has developed the fastest. The more commonly used structure of the front piezoelectric droplet ejection free-forming system is: a tubular piezoelectric ceramic is sheathed in the middle of a glass tube or PVDF tube with a pointed nozzle, and a trapezoidal waveform voltage is applied to both ends of the piezoelectric ceramic, and the "inverse piezoelectric effect" of the piezoelectric ceramic is used to change the diameter of the tubular piezoelectric ceramic. When the diameter of the piezoelectric ceramic becomes larger, the glass tube or PVDF tube begins to absorb liquid; when the diameter of the piezoelectric ceramic becomes smaller, the liquid is squeezed out at the pointed nozzle and forms droplets.

[0004] However, in all kinds of free-form droplet jetting systems, there are common problems: due to the lack of monitoring and planning of the droplet jetting process, it is difficult to avoid the appearance of tail droplets or satellite droplets during the refilling process after the previous droplet is ejected, and it is difficult to ensure the consistency of the ejected droplets. In terms of structure, the current product design generally only involves extrusion of liquid and nozzle structure, and does not pay attention to the feedback element of the liquid state; in terms of drive, the control voltage curve in the current product is generally a simple trapezoidal wave, and no reasonable drive voltage waveform is formulated according to the droplet formation process, and there is a lack of drive planning for high-speed systems; in terms of feedback control, the current product has neither feedback on the motion state of the driven object nor the self-sensing technology characteristics of the "positive piezoelectric effect" of piezoelectric ceramics, resulting in functional waste.

[0005] In short, existing products neither plan the motion state of high-speed systems well nor monitor the system state through feedback. At the same time, the self-sensing function of piezoelectric ceramics as sensors is ignored, resulting in a waste of resources. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a micro-droplet jetting free-forming system and method.

[0007] The present invention discloses a micro-droplet jetting free-forming system, comprising:

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

[0009] A data storage module, the data storage module is used to store a preset motion response, a threshold value allowing a deviation between an actual motion response and a preset motion response, a reference motion plan as a system excitation, and a dynamic motion plan, the reference motion plan being used to initialize the dynamic motion plan;

[0010] A piezoelectric ceramic driving module, the 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, the liquid pressure feedback module is used to receive the voltage signal converted by the self-sensing part, amplify it and perform analog-to-digital conversion; and determine whether the guide tube is broken or the nozzle is blocked according to the voltage signal of the self-sensing part;

[0012] A data processing module, 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 not, excite according to the original motion plan, if exceeded, output a new motion plan;

[0013] A feedforward control module is used to perform neural network training according to 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, and the piezoelectric ceramic tube 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 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 of the outer layer at the end close to or away from the nozzle is connected 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 one end of the guide tube close to the nozzle, and the self-sensing piezoelectric ceramic tube is sleeved on one end of the guide tube away from the nozzle;

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

[0018] As a further improvement of the present invention, the distance from the first high-level electrode connection to the outer end surface of the nozzle is consistent with the distance from the first high-level electrode connection to the second high-level electrode connection.

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

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

[0021] A first voltage amplifying unit, which is used to amplify the shaped voltage curve;

[0022] The voltage stabilizing unit is used to stabilize the amplified voltage curve to form a driving voltage, wherein the high level of the driving voltage is transmitted to the driving part; and the low level of the driving voltage is transmitted to the low level part.

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

[0024] A second voltage amplifying unit, used for amplifying the voltage signal converted by the self-sensing unit;

[0025] An A / D conversion unit, which 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 an equivalent viscosity value for judging 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 clogged; when the equivalent viscosity value suddenly decreases, it is determined that the guide tube is broken or leaking.

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

[0029] Droplet ejection control process, which 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] Amplifying and stabilizing the voltage curve to form a piezoelectric ceramic driving voltage, wherein a high level of the piezoelectric ceramic driving voltage is transmitted to a driving part of the piezoelectric ceramic module, and a low level is transmitted to a low level part of the piezoelectric ceramic module;

[0032] Based on the inverse piezoelectric effect, the piezoelectric ceramic module acts on the guide tube so that the liquid in the guide tube is 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 fluctuation in the guide tube into a voltage signal;

[0035] The liquid pressure feedback module amplifies and performs analog-to-digital conversion on the converted voltage signal, and 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 fluctuation in the guide tube, and retrieves the preset motion response and deviation threshold in the data storage module; compares the actual motion response with the preset motion response and solves the response deviation to determine whether the response deviation exceeds the deviation threshold; if not, the system excites according to the dynamic motion plan of the original motion plan; if exceeded, the feedforward control module is triggered;

[0037] The feedforward control module uses the collected actual motion responses and dynamic motion plans as training samples to perform feedforward control training. After the training is completed, the preset motion responses in the data storage module are read and optimized based on the neural network, and the dynamic motion plan in the data storage module is updated 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 fluctuation in the guide tube into a voltage signal;

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

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

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

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The present invention adds a self-sensing part of the piezoelectric ceramic module to the structure, and adds a data storage module, a piezoelectric ceramic drive module, a liquid pressure feedback module, a data processing module, and a feedforward control module to the control, so that the self-sensing part is organically integrated with each module, and the piezoelectric ceramic self-sensing is fully utilized as a sensing element, which greatly improves the sensing ability of the system, enables the system to capture the subtle changes in the liquid pressure in the guide tube in real time and accurately, can more finely control the droplet formation process, effectively avoids the abnormal droplet injection caused by missing or inaccurate information, and thus improves the stability and reliability of the entire droplet injection free forming process.

[0045] The present invention replans the motion planning of piezoelectric ceramics based on feedforward control, and its scope covers multiple key dimensions such as adjustment of curve morphology, voltage amplitude change, and frequency change. In terms of curve morphology adjustment, the shape of the voltage curve can be optimized based on real-time feedback information to make it more in line with ideal droplet injection requirements. The change in voltage amplitude can accurately control the intensity of the action of the piezoelectric ceramics on the guide tube to ensure that the liquid is squeezed and stretched just right. The adjustment of frequency changes further enhances the control of the droplet injection rhythm, so that the droplets can be stably ejected at a predetermined frequency. Through these comprehensive replanning methods, the system can adapt to different working conditions and environmental changes, always maintain an efficient and stable droplet injection state, greatly improve the forming quality and efficiency, and effectively avoid the appearance of stray droplets such as tail droplets and satellite droplets.

[0046] The present invention realizes self-sensing of whether the nozzle is blocked and whether the guide tube is broken by setting a self-sensing part, avoiding production interruption and product quality problems caused by nozzle blockage or guide tube rupture, and ensuring the continuous and stable operation of the droplet jet free forming system. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic structural diagram of a forming module of a micro-droplet jetting free-forming system disclosed in the first embodiment of the present invention;

[0048] Figure 2 A structural diagram of a guide tube of a micro-droplet jetting free-forming system disclosed in a second embodiment of the present invention;

[0049] Figure 3 A structural diagram of a piezoelectric ceramic module of a micro-droplet jetting free-forming system disclosed in an embodiment of the present invention;

[0050] Figure 4 The system composition and flow chart of a micro-droplet jetting free-forming system disclosed in one embodiment of the present invention;

[0051] Figure 5 A schematic diagram of the structure of a forming module of a micro-droplet jetting free-forming system disclosed in a second embodiment of the present invention;

[0052] Figure 6 A structural side sectional view of a forming module of a micro-droplet jetting free-forming system disclosed in a second embodiment of the present invention;

[0053] Figure 7 A structural side cross-sectional view of a guide tube of a micro-droplet jetting free-forming system disclosed in a second embodiment of the present invention;

[0054] Figure 8 A structural diagram of a driving piezoelectric ceramic tube of a micro-droplet jetting free-forming system disclosed in a second embodiment of the present invention;

[0055] Fig. 9 A structural diagram of a self-sensing piezoelectric ceramic tube of a micro-droplet jetting free-forming system disclosed in a second embodiment of the present invention;

[0056] Fig.10 The system composition and flow chart of the micro-droplet jetting free-forming system disclosed in the second embodiment of the present invention;

[0057] Fig.11 It is a schematic diagram of the voltage curve of the micro-droplet jetting free-forming system disclosed in the present invention.

[0058] In the figure:

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

[0060] 201, 301, 401, low level electrodes;

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

[0062] 203, 303, driving unit;

[0063] 204, 403, self-sensing department. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0066] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0067] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0068] like Figure 1-10 As shown, a micro-droplet jetting free-forming system provided 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 arranged at one end of the guide tube body 101. The cross section of the guide tube body 101 is a circular ring, or 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 squeeze the liquid in the tube; the nozzle 102 can be a tapered hole or a straight hole. Its function is that when the liquid inside the glass tube body is squeezed regularly, the liquid can be sprayed out through the nozzle and form droplets. The piezoelectric ceramic module includes a driving part for squeezing and stretching the guide tube 1, a self-sensing part for monitoring the liquid pressure in the guide tube 1, and a low-level part for cooperating with the driving part and the self-sensing part.

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

[0071] The piezoelectric ceramic driving module 6 includes a curve shaping unit, a first voltage amplifying unit and a voltage stabilizing unit: wherein the curve shaping unit is used to shape the dynamic motion plan read in the data storage module into a voltage curve. For example, assuming that the current operation requires 100Hz (the time of 1 cycle is 0.01s), the maximum voltage across the piezoelectric ceramic is selected as 90V, then the horizontal coordinate of the dynamic motion plan M1 is multiplied by the period coefficient 0.01s, and the vertical coordinate is multiplied by the amplification coefficient 90V. Then the curve of the voltage applied to the high-level electrode of the piezoelectric ceramic driving unit over time is Fig.11 As shown; the first voltage amplifying unit is used to amplify the shaped voltage curve; the voltage stabilizing unit is used to stabilize 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, wherein the second voltage amplification unit is used to amplify the voltage signal converted by the self-sensing part; the A / D conversion unit is used to convert the amplified voltage signal into a digital signal, and transmit the digital signal to the data processing module 8; the signal processing and equivalent viscosity calculation unit is used to process the amplified voltage signal to obtain an equivalent viscosity value for judging whether the guide tube 1 is broken or whether the nozzle 102 is blocked. In actual calculation, based on the self-sensing technology of piezoelectric ceramics, the working state of the droplet injection free forming system can be monitored. The self-sensing ceramic tube and the section of the guide tube 1 and the fluid coated thereon are equivalently regarded as Newtonian fluids, and the attenuation constant of their vibration is:

[0073]

[0074] Where ηfluid is the viscosity, ρ is the fluid density, and k is the 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 and integrated, and its average value is the product of viscosity and density (referred to as 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 an actual motion response R1, and compare the actual motion response R1 with the preset motion response R0 to determine whether it exceeds the deviation threshold H. If not, it is stimulated according to the original motion plan. If it exceeds, it triggers the feedforward control module to quantitatively collect the actual motion response R1 and optimize and refresh the motion plan M1.

[0083] The feedforward control module 9 is triggered by the data processing module 8, and the feedforward control module 9 reads the current motion plan and collects the quantitative actual motion response R1 through the data processing module 8. After training the two through the 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, according to the first embodiment of the present invention, the micro-droplet injection free forming system provides a forming device consisting of a guide tube 1 and a piezoelectric ceramic tube 2. The guide tube 1 is a glass tube, and the guide tube 1 includes a guide tube body 101 and a nozzle 102. The number of the piezoelectric ceramic tube 2 is 1, and the piezoelectric ceramic tube 2 is sleeved on the glass tube, and the nozzle 102 is provided at the end of the glass tube.

[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 a low-level electrode 201 as a whole; the first high-level electrode in the middle section of the outer layer is connected as a driving unit 203; the driving unit 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 in the tube, and causes the liquid to produce droplets at the nozzle 102. A low-level wiring point 202 is set at the end of the outer layer away from the nozzle 102, and the low-level wiring 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 wiring point 202; the second high-level electrode at the end of the outer layer close to or away from the nozzle 102 is connected as a self-sensing unit 204. The self-sensing unit 204 cooperates with the low-level electrode 201 to monitor the liquid pressure in the guide tube body 101 based on the positive piezoelectric effect, and converts its state into a voltage signal to transmit to the liquid pressure feedback module 7.

[0087] like Figure 4 As shown, in the above embodiment, preferably, the control method of the droplet jetting free-forming device of this embodiment includes:

[0088] Droplet ejection control process, which includes:

[0089] 1) After the micro-droplet jetting free-forming device is started, the piezoelectric ceramic driving 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 changing with time;

[0090] 2) After the voltage curve is amplified and stabilized by the first voltage amplification unit and the voltage stabilization unit, a piezoelectric ceramic driving voltage is formed. The high level of the driving voltage is transmitted to the driving part 203 of 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 of 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. This change acts on the guide tube 1 and indirectly causes the liquid pressure in the guide tube 1 to change in an orderly manner according to a predetermined state.

[0092] 4) Under the action of pressure, the liquid is sprayed out from the 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 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 in the pipe through calculation; after retrieving the preset motion response R0 and the deviation threshold H in the data storage module 5, the actual motion response R1 is compared with the preset motion response R0, the response deviation △R=|R1-R0| is solved, and it is determined whether the response deviation △R exceeds the deviation threshold H;

[0097] If the degree of deviation does not exceed the deviation threshold H, the system excites the system according to the original motion plan; if the degree of deviation exceeds the deviation threshold H, the feedforward control module 9 is triggered;

[0098] 4) After the feedforward control module 9 is triggered, the system triggers an alarm for abnormal pressure fluctuation and reports a fault; at the same time, the system starts voltage curve adjustment, and the feedforward control module 9 uses the actual motion response R1 and dynamic motion planning M1 collected recently 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 portion 204 on the piezoelectric ceramic tube 2 monitors the pressure fluctuation inside the guide tube body 101 in real time.

[0101] The guide tube 1 status detection process 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 the pressure fluctuation in each cycle, the amplified attenuation waveform is rectified and integrated, and the average value is calculated as the equivalent viscosity;

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

[0105] Example 2

[0106] like Figure 5-10 As shown, according to the second embodiment of the present invention, a droplet injection free forming system is provided, and its forming device is composed 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 the guide tube 1 includes a guide tube body 101 and a nozzle 102. The driving piezoelectric ceramic tube is sleeved at one end of the guide tube 1 close to the nozzle 102, and the self-sensing piezoelectric ceramic tube is sleeved at one 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 is composed of an inner layer and an outer layer. The inner layer is a low-level electrode 301 as a whole, and the outer layer is composed of a low-level wiring point 302 and a driving unit 303, and the driving unit 303 is composed of a first high-level electrode wiring arranged on the outer layer of the driving piezoelectric ceramic tube 3. The driving unit 303, in cooperation with the low-level electrode 301, squeezes and stretches the guide tube body 101 through the inverse piezoelectric effect and indirectly affects the liquid in the tube, and causes the liquid to produce droplets at the nozzle 102.

[0108] like Fig. 9 As shown, in the above embodiment, preferably, the self-sensing piezoelectric ceramic tube 4 is composed of an inner layer and an outer layer. The inner layer is a low-level electrode 401 as a whole, and the outer layer is composed of a low-level wiring point 402 and a self-sensing part 403, and the self-sensing part 403 is composed of a second high-level electrode wiring arranged on the outer layer of the self-sensing piezoelectric ceramic tube 4. The self-sensing part 403 cooperates with the low-level electrode 401 to monitor the liquid pressure in the guide tube body 101 based on the positive piezoelectric effect, and converts its state into a voltage signal to transmit to the liquid pressure feedback module 7.

[0109] In the above embodiment, preferably, after assembly, the distance from the length center of the driving part 303 to the outer end surface of the nozzle 102 is L1, and the distance from the length center of the driving part 303 to the length center of the self-sensing part 403 is L2. In this embodiment, L1=L2, and based on symmetry, the pressure fluctuation at the length center of the self-sensing part 403 is regarded as consistent with the pressure fluctuation at the outer end surface of the nozzle 102, so as to achieve indirect measurement and monitoring.

[0110] In the above embodiment, the self-sensing part in Embodiment 1 may also be retained on the driving piezoelectric ceramic tube 3, and the pressure fluctuation on the outer end surface of the nozzle 102 may be calculated through the fluctuation delay and position passing through each sensing part.

[0111] like Fig.10 As shown, in the above embodiment, preferably, the control method of the droplet jetting free-forming device of this embodiment includes:

[0112] Droplet ejection control process, which includes:

[0113] 1) After the micro-droplet jetting free-forming device is started, the piezoelectric ceramic driving 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 changing with time;

[0114] 2) After the voltage curve is amplified and stabilized by the first voltage amplification unit and the voltage stabilization unit, a piezoelectric ceramic driving voltage is formed. The high level of the 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 wiring 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 in the guide tube 1 to change in an orderly manner according to a predetermined state.

[0116] 4) Under the action of pressure, the liquid is sprayed out from the 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 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 in the pipe through calculation; after retrieving the preset motion response R0 and the deviation threshold H in the data storage module 5, the actual motion response R1 is compared with the preset motion response R0, the response deviation △R=|R1-R0| is solved, and it is determined whether the response deviation △R exceeds the deviation threshold H;

[0121] If the degree of deviation does not exceed the deviation threshold H, the system excites the system according to the original motion plan; if the degree of deviation exceeds the deviation threshold H, the feedforward control module 9 is triggered;

[0122] 4) After the feedforward control module 9 is triggered, the system triggers an alarm for abnormal pressure fluctuation and reports a fault; at the same time, the system starts voltage curve adjustment, and the feedforward control module 9 uses the actual motion response R1 and dynamic motion planning M1 collected recently 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 portion 403 on the self-sensing piezoelectric ceramic tube 4 monitors the pressure fluctuation inside the guide tube body 101 in real time.

[0125] The guide tube 1 status detection process 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 the pressure fluctuation in each cycle, the amplified attenuation waveform is rectified and integrated, and the average value is calculated as the equivalent viscosity;

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

[0129] The beneficial effects of the present invention are:

[0130] The present invention adds a self-sensing part of the piezoelectric ceramic module to the structure, and adds a data storage module 5, a piezoelectric ceramic drive module 6, a liquid pressure feedback module 7, a data processing module 8, and a feedforward control module 9 to the control, so that the self-sensing part is organically integrated with each module, and the piezoelectric ceramic self-sensing is fully utilized as a sensing element, which greatly improves the sensing ability of the system, enables the system to capture the subtle changes in the liquid pressure in the guide tube in real time and accurately, and can more finely control the droplet formation process, effectively avoid the abnormal droplet injection caused by missing or inaccurate information, and thus improve the stability and reliability of the entire droplet injection free forming process.

[0131] The present invention replans the motion planning of piezoelectric ceramics based on feedforward control, and its scope covers multiple key dimensions such as adjustment of curve morphology, voltage amplitude change, and frequency change. In terms of curve morphology adjustment, the shape of the voltage curve can be optimized based on real-time feedback information to make it more in line with ideal droplet injection requirements. The change in voltage amplitude can accurately control the intensity of the action of the piezoelectric ceramics on the guide tube to ensure that the liquid is squeezed and stretched just right. The adjustment of frequency changes further enhances the control of the droplet injection rhythm, so that the droplets can be stably ejected at a predetermined frequency. Through these comprehensive replanning methods, the system can adapt to different working conditions and environmental changes, always maintain an efficient and stable droplet injection state, greatly improve the forming quality and efficiency, and effectively avoid the appearance of stray droplets such as tail droplets and satellite droplets.

[0132] The present invention realizes self-sensing of whether the nozzle 102 is blocked and whether the guide tube 1 is broken by setting a self-sensing part, thereby avoiding production interruption and product quality problems caused by nozzle 102 blockage or guide tube 1 rupture, and ensuring the continuous and stable operation of the droplet injection free forming system.

[0133] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A droplet jetting free-forming system, characterized in that: include: A forming module, the forming module comprises a guide tube and a piezoelectric ceramic module acting on the guide tube, one end of the guide tube is provided with a nozzle; the piezoelectric ceramic module comprises a driving part for squeezing and stretching the guide tube, a self-sensing part for monitoring the liquid pressure in the guide tube, and a low-level part for cooperating with the driving part and the self-sensing part; A data storage module, the data storage module is used to store a preset motion response, a threshold value allowing a deviation between an actual motion response and a preset motion response, a reference motion plan as a system excitation, and a dynamic motion plan, the reference motion plan being used to initialize the dynamic motion plan; A piezoelectric ceramic driving module, the 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, the liquid pressure feedback module is used to receive the voltage signal converted by the self-sensing part, amplify it and perform analog-to-digital conversion; and determine whether the guide tube is broken or the nozzle is blocked according to the voltage signal of the self-sensing part; A data processing module, 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 not, excite according to the original motion plan, if exceeded, output a new motion plan; A feedforward control module is used to perform neural network training according to 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 droplet jetting free-forming system according to claim 1, characterized in that: The piezoelectric ceramic module comprises a piezoelectric ceramic tube, and the piezoelectric ceramic tube 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 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 of the outer layer at the end close to or away from the nozzle is connected as the self-sensing part.

3. The droplet jetting free-forming 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, wherein the driving piezoelectric ceramic tube is sleeved on one end of the guide tube close to the nozzle, and the self-sensing piezoelectric ceramic tube is sleeved on one end of the guide tube away from the nozzle; The driving piezoelectric ceramic tube and the self-sensing piezoelectric ceramic tube are both composed of an inner layer and an outer layer. The inner layers of the driving piezoelectric ceramic tube and the self-sensing piezoelectric ceramic tube are both low-level electrodes. The outer layer of the driving piezoelectric ceramic tube is composed of a low-level wiring point and a first high-level electrode wiring. The outer layer of the self-sensing piezoelectric ceramic tube is composed of a low-level wiring point and a second high-level electrode wiring. The first high-level electrode wiring constitutes the driving part, and the second high-level electrode wiring constitutes the self-sensing part.

4. The droplet jetting free-forming system according to claim 3, characterized in that: The distance from the first high-level electrode connection to the outer end surface of the nozzle is consistent with the distance from the first high-level electrode connection to the second high-level electrode connection.

5. The droplet jetting free-forming system according to claim 1, characterized in that: The piezoelectric ceramic driving module comprises: A curve shaping unit, used for shaping the dynamic motion plan read from the data storage module into a voltage curve; A first voltage amplifying unit, which is used to amplify the shaped voltage curve; The voltage stabilizing unit is used to stabilize the amplified voltage curve to form a driving voltage, wherein the high level of the driving voltage is transmitted to the driving part; and the low level of the driving voltage is transmitted to the low level part.

6. The droplet jetting free-forming system according to claim 1, characterized in that: The liquid pressure feedback module comprises: A second voltage amplifying unit, used for amplifying the voltage signal converted by the self-sensing unit; An A / D conversion unit, which 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 an equivalent viscosity value for judging whether the guide tube is broken or the nozzle is blocked.

7. The droplet jetting free-forming system according to claim 6, characterized in that: When the equivalent viscosity value suddenly increases, it is determined that the nozzle is clogged; when the equivalent viscosity value suddenly decreases, it is determined that the guide tube is broken or leaking.

8. A control method for a micro-droplet jetting free-forming device, applied to the micro-droplet jetting free-forming system according to any one of claims 1 to 7, characterized in that: include: Droplet ejection control process, which 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; Amplifying and stabilizing the voltage curve to form a piezoelectric ceramic driving voltage, wherein a high level of the piezoelectric ceramic driving voltage is transmitted to a driving part of the piezoelectric ceramic module, and a low level is transmitted to a low level part of the piezoelectric ceramic module; Based on the inverse piezoelectric effect, the piezoelectric ceramic module acts on the guide tube so that the liquid in the guide tube is 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 fluctuation in the guide tube into a voltage signal; The liquid pressure feedback module amplifies and performs analog-to-digital conversion on the converted voltage signal, and 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 fluctuation in the guide tube, and retrieves the preset motion response and deviation threshold in the data storage module; compares the actual motion response with the preset motion response and solves the response deviation to determine whether the response deviation exceeds the deviation threshold; if not, the system excites according to the dynamic motion plan of the original motion plan; if exceeded, the feedforward control module is triggered; The feedforward control module uses the collected actual motion responses and dynamic motion plans as training samples to perform feedforward control training. After the training is completed, the preset motion responses in the data storage module are read and optimized based on the neural network, and the dynamic motion plan in the data storage module is updated based on the optimized voltage curve.

9. The control method according to claim 8, characterized in that: Also included is 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 fluctuation in the guide tube into a voltage signal; The liquid pressure feedback module amplifies the converted voltage signal, rectifies and integrates the decay waveform of the decay period of each cycle of pressure fluctuation, and calculates the average value as the equivalent viscosity value; When the equivalent viscosity value suddenly increases, it is determined that the nozzle is clogged; when the equivalent viscosity value suddenly decreases, it is determined that the guide tube is broken or leaking.

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

Images