An FDM ceramic 3D printing device

Abstract

The present invention relates to the technical field of 3D printing devices, and provides an FDM ceramic 3D printing device, which solves the problems of the decrease in the interlayer bonding strength and the accumulation of dimensional deviations caused by nozzle blockage in the prior art. The present invention includes a frame; an X-axis translation assembly provided at the top of the frame; a nozzle assembly provided on the X-axis translation assembly, an extrusion flow channel and a discharge port communicated with the extrusion flow channel are arranged inside the nozzle assembly; a reversible driving mechanism connected to the extrusion flow channel for driving the material in the extrusion flow channel to be extruded forward or sucked back reversely; a pressure sensor arranged on one side of the extrusion flow channel for real-time monitoring of the pressure in the extrusion flow channel; by monitoring the pressure change and the pressure change rate in the extrusion flow channel, the abnormal pressure rise before nozzle blockage can be accurately captured, and the clogging removal operation can be triggered in advance.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing devices, and in particular to an FDM ceramic 3D printing device. Background Art

[0002] FDM ceramic 3D printing is a method of 3D printing ceramic materials using Fused Deposition Modeling (FDM) technology. FDM technology heats ceramic powder or particles to a molten state, and then deposits them layer by layer through an extruder to eventually form a three-dimensional object. This technology is particularly suitable for making ceramic parts with complex shapes and can achieve high precision and details.

[0003] In the 3D printing applications of high-solid content ceramic materials (such as alumina and silicon carbide), the fused deposition modeling (FDM) technology faces the problem of nozzle clogging due to the complex rheological properties of the materials. The ceramic slurry is prone to form gradual clogging in the flow channel, resulting in a decrease in interlayer bonding strength and accumulation of dimensional deviations. Summary of the invention

[0004] Therefore, in view of the above problems, the present invention provides an FDM ceramic 3D printing device to solve the existing problems of decreased interlayer bonding strength and accumulated dimensional deviations due to nozzle clogging.

[0005] To achieve the above object, the present invention is achieved through the following technical solutions:

[0006] An FDM ceramic 3D printing device comprises a frame and an X-axis translation assembly arranged on the top of the frame, and further comprises: a nozzle assembly arranged on the X-axis translation assembly, wherein an extrusion flow channel and a discharge port communicating with the extrusion flow channel are arranged inside the nozzle assembly;

[0007] A reversible driving mechanism connected to the extrusion flow channel, used to drive the material in the extrusion flow channel to be extruded forward or sucked backward; a pressure sensor, provided on one side of the extrusion flow channel, used to monitor the pressure in the extrusion flow channel in real time;

[0008] A heater, the heater is arranged in the extrusion flow channel, the heater comprises a near-section heater and a far-section heater, and the far-section heater is arranged close to the discharge port;

[0009] A control module is electrically connected to the reversible drive mechanism, the pressure sensor and the heater, and the control module is configured as follows: when the reversible drive mechanism performs a forward extrusion operation, when the pressure sensor detects that the pressure in the extrusion flow channel exceeds a preset threshold, the remote heater is controlled to be consistent in temperature with the near heater, and the reversible drive mechanism is controlled to perform a reverse suction operation. After the reverse suction operation is completed, it is determined whether the clearing is successful based on the feedback from the pressure sensor. If successful, the remote heater is restored to an initial temperature, and the reversible drive mechanism is controlled to compensate for subsequent extrusion flow based on a pressure recovery curve in the extrusion flow channel.

[0010] Furthermore, it also includes an ultrasonic transducer, which is arranged on the outer side of the nozzle assembly or the inner wall of the extrusion flow channel, and the control module is further configured as follows:

[0011] If the pressure in the extrusion flow channel does not return to a normal range after the reversible driving mechanism performs a reverse suction operation, the ultrasonic transducer is activated to perform high-frequency vibration.

[0012] Furthermore, the working mode of the ultrasonic transducer is pulse vibration, the frequency range of which is 20-40kHz, the duration of a single vibration is at most 5 seconds, and the interval time is at least 1 second.

[0013] Furthermore, the temperature range of the near-section heater is 220-280°C, the temperature range of the far-section heater is 90-220°C, and the temperature difference between the near-section heater and the far-section heater is ≥130°C.

[0014] Furthermore, one side of the extrusion flow channel of the nozzle assembly is connected to one end of a bypass channel, and the other end of the bypass channel is connected to the outside of the nozzle assembly. The bypass channel is connected to the extrusion flow channel when the reversible driving mechanism performs reverse suction.

[0015] Furthermore, the algorithm for compensating the subsequent extrusion flow rate of the control module includes:

[0016] Obtain the pressure recovery curve after clearing the blockage in the time window t 0 to 1 The slope S within

[0017] According to the slope S and the preset standard slope S ref The extrusion flow rate is adjusted according to the following rules:

[0018] When S / S ref When <0.8, the compensation flow rate is 120%-150% of the theoretical extrusion volume;

[0019] When 0.8≤S / S ref When ≤1.2, the compensation flow is 100% of the theoretical extrusion volume;

[0020] When S / S ref When >1.2, the compensation flow rate is 80%-90% of the theoretical extrusion volume.

[0021] Furthermore, the reversible driving mechanism increases the reverse suction force in a step-by-step manner during the reverse suction process.

[0022] Furthermore, when the reversible driving mechanism performs a reverse suction operation, a layered suction strategy is implemented:

[0023] The first stage is to pump at a constant rate, lasting 0.5s-2s;

[0024] The second stage is pulsed suction, with a single suction volume of 0.1-0.3mm 3 After that, the pressure is kept still and the number of repetitions is dynamically adjusted based on the attenuation amplitude of the pressure change rate.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention monitors the flow channel pressure in real time through a pressure sensor, and automatically triggers reverse suction to clear the blockage when it is blocked, thereby solving the problem of printing interruption caused by clogging of ceramic materials due to high viscosity, avoiding the problem of decreased interlayer bonding strength and accumulated dimensional deviations due to nozzle blockage, and significantly reducing material loss and time cost.

[0027] 2. The present invention ensures that the ceramic slurry is fully plasticized by the near-end heater and prevents the material at the outlet from solidifying prematurely by the far-end heater. The synergistic effect of the two enables the material to form a controllable viscosity gradient in the flow channel, thereby reducing the flow channel resistance. When the risk of blockage is detected, the far-end heater is heated to the same temperature as the near-end, which can quickly eliminate the material solidification boundary layer caused by the temperature difference, making it easier for the blockage to detach from the flow channel wall during the suction operation.

[0028] 3. The present invention can accurately capture the abnormal pressure rise before the nozzle is blocked by monitoring the pressure change and the pressure change rate in the extrusion flow channel, and trigger the clearing operation in advance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the control module flow of an embodiment of the present invention;

[0030] Figure 2 It is a schematic diagram of the structure of an embodiment of the present invention;

[0031] Figure 3 It is a schematic diagram of the cross-sectional structure of the nozzle assembly according to an embodiment of the present invention.

[0032] Description of Figure Numbers

[0033] Rack 1;

[0034] X-axis translation component 2;

[0035] Nozzle assembly 3; extrusion flow channel 31; discharge port 32; bypass channel 33; solenoid valve 34;

[0036] Pressure sensor 4;

[0037] Heater 5; near section heater 51; far section heater 52;

[0038] Control module 6;

[0039] Ultrasonic transducer 7. DETAILED DESCRIPTION

[0040] The following will describe the implementation methods of the present invention in detail in conjunction with specific embodiments, so that the implementation process of how the present invention applies technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0041] Embodiment 1:

[0042] like Figures 1 to 3 As shown, an FDM ceramic 3D printing device includes a frame 1 and an X-axis translation assembly 2 arranged on the top of the frame 1, and also includes:

[0043] The nozzle assembly 3 is arranged on the X-axis translation assembly 2, and the nozzle assembly 3 is provided with an extrusion flow channel 31 and a discharge port 32 connected with the flow channel;

[0044] A reversible driving mechanism (not shown in the figure), connected to the extrusion flow channel 31, for driving the material in the extrusion flow channel 31 to be extruded forward or sucked backward;

[0045] A pressure sensor 4, disposed on one side of the extrusion flow channel 31, for real-time monitoring of the pressure in the extrusion flow channel 31;

[0046] A heater 5, wherein the heater 5 is disposed in the extrusion flow channel 31, and the heater 5 includes a near-section heater 51 and a far-section heater 52, and the far-section heater 52 is disposed close to the discharge port 32;

[0047] The control module 6 is electrically connected to the reversible driving mechanism, the pressure sensor 4 and the heater 5, and the control module 6 is configured as follows:

[0048] When the reversible drive mechanism performs a forward extrusion operation, when the pressure sensor 4 detects that the pressure in the extrusion channel 31 exceeds a preset threshold, the temperature of the distal heater 52 is controlled to be consistent with that of the proximal heater 51, and the reversible drive mechanism is controlled to perform a reverse suction operation. After the reverse suction operation is completed, it is determined whether the clearing is successful based on the feedback from the pressure sensor 4. If successful, the distal heater 52 is restored to its initial temperature, and the reversible drive mechanism is controlled to compensate for the subsequent extrusion flow based on the pressure recovery curve in the extrusion channel 31.

[0049] Among them, the X-axis translation assembly 2 is realized by a slide rail and a pulley, which is a prior art procedure; the reversible drive mechanism adopts a pneumatic or hydraulic system, which is a prior art means; the heater 5 adopts a ceramic heating tube, which can be purchased on the market; the control module 6 adopts a single-chip microcomputer or a PLC (programmable logic controller), which can be purchased on the market and will not be repeated here.

[0050] It also includes an ultrasonic transducer 7, which is arranged on the outside of the nozzle assembly 3. The control module 6 is further configured as follows: if the pressure in the extrusion channel 31 does not return to the normal range after the reversible drive mechanism performs the reverse suction operation, the ultrasonic transducer 7 is activated to perform high-frequency vibration; ultrasonic high-frequency vibration is superimposed on mechanical suction to break up stubborn blockages through cavitation effect, which is particularly suitable for ceramic composite materials containing fiber-reinforced phases. Reverse suction with lower energy consumption is preferred, and ultrasonic waves are enabled only when necessary to reduce energy consumption by 20%-30%; the ultrasonic transducer 7 adopts a piezoelectric ceramic ring transducer, which can be purchased on the market and will not be repeated here.

[0051] The working mode of the ultrasonic transducer 7 is pulse vibration, and its frequency range is 20-40kHz. The corresponding vibration frequency is automatically matched according to different printing materials to improve energy utilization. The duration of a single vibration is 5 seconds and the interval time is 1 second. The pulse vibration is combined with forced interval to avoid overheating and failure of the ultrasonic transducer and extend the life of the device.

[0052] The temperature range of the near-section heater 51 is 220-280°C, the temperature range of the far-section heater 52 is 90-220°C, and the temperature difference between the near-section heater 51 and the far-section heater 52 is ≥130°C. The corresponding heater temperature is matched according to the characteristics of different printing materials, and this application does not make specific limitations.

[0053] One side of the extrusion channel 31 of the nozzle assembly 3 is connected to one end of the bypass channel 33, and the other end of the bypass channel 33 is connected to the outside of the nozzle assembly 3. The bypass channel 33 is connected to the extrusion channel 31 when the reversible driving mechanism performs reverse suction. The extrusion channel 31 and the bypass channel 33 are separated and connected by a solenoid valve 34, which is a prior art means and will not be described in detail here. The bypass channel 33 forms an auxiliary channel during suction to avoid excessive negative pressure causing an increase in the porosity of the material. At the same time, a collection box (not shown in the figure) connected to the bypass channel 33 is provided on the outside of the nozzle assembly 3 to guide the sucked semi-solidified material into the collection box to reduce the risk of channel contamination.

[0054] The algorithm of the control module 6 for compensating the subsequent extrusion flow rate includes:

[0055] Obtain the pressure recovery curve after clearing the blockage in the time window t 0 to 1 The slope S within

[0056] According to the slope S and the preset standard slope S ref The extrusion flow rate is adjusted according to the following rules:

[0057] When S / S ref When <0.8, the compensation flow rate is 120%-150% of the theoretical extrusion volume;

[0058] When 0.8≤S / S ref When ≤1.2, the compensation flow is 100% of the theoretical extrusion volume;

[0059] When S / S ref When >1.2, the compensation flow rate is 80%-90% of the theoretical extrusion volume.

[0060] The extrusion volume is calibrated in real time through the pressure recovery slope to reduce the error of the first layer printing thickness after clearing the blockage. The standard slope S ref Multiple sets of parameters can be preset according to the rheological properties of different ceramic slurries to adapt to multi-material printing scenarios.

[0061] When the reversible driving mechanism performs the reverse suction operation, a layered suction strategy is implemented:

[0062] The first stage is to pump at a constant rate, lasting 0.5s-2s;

[0063] The second stage is pulsed suction, with a single suction volume of 0.1-0.3mm 3 After that, it is kept still and the number of repetitions is dynamically adjusted based on the attenuation amplitude of the pressure change rate, that is, when the attenuation amplitude of the pressure change rate is large, the number of pulse suctions in the second stage is reduced accordingly.

[0064] The main blockage is cleared through constant suction in the first stage to improve the clearing efficiency. Part of the residue is processed through pulse suction in the second stage. The number of repetitions is dynamically adjusted based on the attenuation amplitude of the pressure change rate to avoid invalid suction operations.

[0065] Embodiment 2:

[0066] Different from the first embodiment, the reversible driving mechanism increases the reverse suction force in a step-by-step manner during the reverse suction process, specifically:

[0067] During the first reverse suction, the reversible drive mechanism operates at 80% of the rated power;

[0068] If the pressure does not drop, the subsequent suction is increased to 100% and 120% of the rated power respectively.

[0069] The suction force increases at each level, gradually breaking through blockages with different adhesion forces. Dynamic force adjustment can avoid abnormal negative pressure in the flow channel caused by excessive suction.

[0070] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, it should be understood by those skilled in the art that various changes may be made to the present invention in form and details without departing from the spirit and scope of the present invention as defined by the appended claims, all of which are within the scope of protection of the present invention.

Claims

1. An FDM ceramic 3D printing device, comprising a frame and an X-axis translation assembly arranged on the top of the frame, characterized in that: Also includes: A nozzle assembly is arranged on the X-axis translation assembly, wherein an extrusion flow channel and a discharge port connected to the extrusion flow channel are arranged inside the nozzle assembly; A reversible driving mechanism connected to the extrusion flow channel, used to drive the material in the extrusion flow channel to be extruded forward or sucked backward; a pressure sensor, provided on one side of the extrusion flow channel, used to monitor the pressure in the extrusion flow channel in real time; A heater, the heater is arranged in the extrusion flow channel, the heater comprises a near-section heater and a far-section heater, and the far-section heater is arranged close to the discharge port; A control module is electrically connected to the reversible drive mechanism, the pressure sensor and the heater, and the control module is configured as follows: When the reversible drive mechanism performs a forward extrusion operation, when the pressure sensor detects that the pressure in the extrusion flow channel exceeds a preset threshold, the temperature of the remote heater is controlled to be consistent with that of the near heater, and the reversible drive mechanism is controlled to perform a reverse suction operation. After the reverse suction operation is completed, it is determined whether the clearing is successful based on the feedback from the pressure sensor. If successful, the remote heater is restored to the initial temperature, and the reversible drive mechanism is controlled to compensate for the subsequent extrusion flow based on the pressure recovery curve in the extrusion flow channel.

2. The FDM ceramic 3D printing device according to claim 1, characterized in that: It also includes an ultrasonic transducer, which is arranged on the outer side of the nozzle assembly or the inner wall of the extrusion flow channel. The control module is further configured as follows: If the pressure in the extrusion flow channel does not return to a normal range after the reversible driving mechanism performs a reverse suction operation, the ultrasonic transducer is activated to perform high-frequency vibration.

3. The FDM ceramic 3D printing device according to claim 2, characterized in that: The working mode of the ultrasonic transducer is pulse vibration, the frequency range of which is 20-40 kHz, the duration of a single vibration is at most 5 seconds, and the interval time is at least 1 second.

4. The FDM ceramic 3D printing device according to claim 1, characterized in that: The temperature range of the near-section heater is 220-280°C, the temperature range of the far-section heater is 90-220°C, and the temperature difference between the near-section heater and the far-section heater is greater than or equal to 130°C.

5. The FDM ceramic 3D printing device according to claim 1, characterized in that: One side of the extrusion flow channel of the nozzle assembly is connected to one end of the bypass channel, and the other end of the bypass channel is communicated with the outside of the nozzle assembly. The bypass channel is communicated with the extrusion flow channel when the reversible driving mechanism performs reverse suction.

6. The FDM ceramic 3D printing device according to claim 1, characterized in that: The reversible driving mechanism increases the reverse suction force in a step-by-step manner during the reverse suction process.

7. The FDM ceramic 3D printing device according to claim 1, characterized in that: When the reversible driving mechanism performs the reverse suction operation, a layered suction strategy is implemented: The first stage is to pump at a constant rate, lasting 0.5s-2s; The second stage is pulsed suction, with a single suction volume of 0.1-0.3mm 3 After that, the pressure is kept still and the number of repetitions is dynamically adjusted based on the attenuation amplitude of the pressure change rate.

8. The FDM ceramic 3D printing device according to claim 1, characterized in that: The algorithm of the control module to compensate for the subsequent extrusion flow rate includes: Obtain the slope S of the pressure recovery curve after the blockage is cleared within the time window t0 to t1; According to the ratio of slope S to the preset standard slope Sref, adjust the extrusion flow rate according to the following rules: When S / Sref<0.8, the compensation flow rate is 120%-150% of the theoretical extrusion amount; When 0.8≤S / Sref≤1.2, the compensation flow rate is 100% of the theoretical extrusion amount; When S / Sref>1.2, the compensation flow rate is 80%-90% of the theoretical extrusion amount.

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