Multi-material 3D printing nozzle with self-cleaning function and printing method

Abstract

The invention discloses a multi-material 3D printing nozzle with a self-cleaning function and a printing method.The multi-material 3D printing nozzle comprises a motor, a nozzle mixing inner cavity, a mixing extrusion reducing screw, a discharging pipe and an ultrasonic vibrator, the nozzle mixing inner cavity is of a cylindrical structure, and a feeding port, a cleaning liquid inlet and a hot air inlet are formed in the end of the nozzle mixing inner cavity; the end part of the mixed extrusion reducing screw rod is connected with a motor, the main body part of the mixed extrusion reducing screw rod is arranged in the nozzle mixing inner cavity in a matched manner along the axial direction, and the volume of a thread groove is gradually reduced and the diameter of the screw rod is gradually increased along the direction from the feed port to the discharge pipe to form a progressive compression channel; and the ultrasonic vibrator is arranged around the outer side of the nozzle mixing inner cavity. Automatic cleaning of the spray head in the printing process is achieved, the printing efficiency and quality are improved, and the production cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of 3D printing nozzles, and specifically relates to a multi-material 3D printing nozzle with a self-cleaning function and a printing method, aiming to solve the problems of nozzle blockage and difficulty in cleaning in the event of material contamination during multi-material 3D printing. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] With the rapid development of 3D printing technology, multi-material 3D printing has shown great application prospects due to its ability to integrate multiple materials into a single build process to create complex objects. However, multi-material printing nozzles face significant challenges in practical applications, with material contamination and nozzle clogging being particularly prominent.

[0004] These challenges mainly stem from two aspects: First, the physical and chemical properties of different materials (such as viscosity and curing shrinkage / expansion rate) vary greatly. High-viscosity materials have high flow resistance in the nozzle and are prone to adhere to the inner wall; and the volume change during the curing process may cause the internal structure of the nozzle to deform, affecting the smooth extrusion of the material. When multiple materials are used alternately in the nozzle, these differences will significantly increase the risk of material residue and clogging; second, during the printing process, a small amount of material will inevitably remain inside the nozzle. If these residues are not removed in time, they will gradually accumulate. This will not only directly affect the extrusion quality of subsequent materials and lead to reduced printing accuracy, but will also induce nozzle clogging. In case of severe blockage, the nozzle may even need to be replaced, which greatly increases the printing cost and time cost.

[0005] Traditional cleaning methods generally involve manual disassembly and cleaning, which is cumbersome and time-consuming, and can easily damage precision nozzle components, making it difficult to meet the needs of efficient and continuous 3D printing production. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a multi-material 3D printing nozzle and printing method with a self-cleaning function, which realizes automatic cleaning of the nozzle during the printing process, improves printing efficiency and quality, and reduces production costs.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions: In a first aspect, the present invention provides a multi-material 3D printing nozzle with a self-cleaning function, comprising a motor, a nozzle mixing cavity, a mixing extrusion variable diameter screw, a discharge pipe and an ultrasonic vibrator, wherein: The mixing cavity of the nozzle is a cylindrical structure, and a feed port, a cleaning liquid inlet and a hot air inlet are provided at its end; The end of the mixing extrusion variable diameter screw is connected to the motor, and its main body is axially arranged in the mixing cavity of the nozzle. From the feed port to the discharge pipe, the volume of its thread groove gradually decreases and the screw diameter gradually increases, forming a progressive compression channel. The ultrasonic vibrator is arranged around the outer side of the mixing cavity of the nozzle.

[0008] In a second aspect, the present invention provides a multi-material 3D printing method with a self-cleaning function, comprising the following steps: The printing material is injected into the mixing cavity of the nozzle through the feed port, and the material is progressively compressed and mixed and extruded using a mixing extrusion variable diameter screw. At the same time, an ultrasonic vibrator is used to apply ultrasound to the mixing cavity of the nozzle to promote mixing; After printing is completed, when cleaning is required, move to the cleaning tank, introduce cleaning liquid into the mixing cavity of the nozzle through the cleaning liquid inlet, and apply ultrasound for cleaning.

[0009] The beneficial effects achieved by one or more embodiments of the present invention are as follows: The thread diameter of the variable diameter screw changes non-uniformly along the axial direction. When the variable diameter screw rotates, the volume of the thread groove gradually decreases from the feed end to the discharge end, so that the material is continuously compressed during the conveying process, thereby enhancing the driving force for high-viscosity materials.

[0010] The variable diameter structure of the variable diameter screw creates an axial extrusion force during rotation, pushing residual material toward the nozzle, eliminating dead corners. The volume of the thread groove gradually decreases from the feed end to the discharge end, creating a high-pressure zone that easily squeezes out residual material and achieves self-cleaning.

[0011] For high-viscosity materials, using a variable diameter screw for progressive compression can prevent sudden solidification of the high-viscosity material under pressure and reduce the risk of adhesion to the inner wall. The increased screw diameter can provide stronger conveying force, ensuring smooth extrusion of high-viscosity materials.

[0012] Cleaning liquid can also be introduced into the cleaning liquid inlet to perform thorough cleaning.

[0013] Ultrasonic vibrators surround the nozzle's mixing chamber, applying ultrasonic force to the material during mixing and extrusion, helping to improve mixing. They can also apply ultrasonic force to the cleaning process during the injection of cleaning fluid, aiding rapid cleaning. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0015] Figure 1This is a schematic structural diagram of a multi-material 3D printer according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the 3D printing nozzle and fixture structure according to an embodiment of the present invention; Figure 3 for Figure 2 sectional view of Figure 4 This is a schematic structural diagram of the four feed ports of the nozzle according to an embodiment of the present invention.

[0016] In the figure: 1 - printer frame; 2 - X-axis motion module; 3 - Z-axis motion module; 4 - Y-axis motion module; 5 - printing platform; 6 - X-axis fixture; 7 - printhead fixing plate; 8 - printhead integral part; 9 - cleaning waste liquid tank; 7001 - printhead fixing plate inner plate; 7002 - funnel-shaped fixture; 7003 - circular fixture; 8001 - motor; 8002 - bearing housing connector; 8003 - ultrasonic vibrator; 8004-nozzle nozzle; 8005-electromagnetic heating coil; 8006-motor fixing plate; 8007-mixing extrusion reducing screw; 8008-feed port; 8009-nozzle mixing cavity; 8010-bearing jacket; 8011-bearing; 8012-bearing retaining ring; 80081-cleaning liquid inlet; 80082-first feed port; 80083-hot air inlet; 80084-second feed port. DETAILED DESCRIPTION

[0017] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0018] In a first aspect, the present invention provides a multi-material 3D printing nozzle with a self-cleaning function, comprising a motor, a nozzle mixing cavity, a mixing extrusion variable diameter screw, a discharge pipe and an ultrasonic vibrator, wherein: The mixing cavity of the nozzle is a cylindrical structure, and a feed port, a cleaning liquid inlet and a hot air inlet are provided at its end; The end of the mixing extrusion variable diameter screw is connected to the motor, and its main body is axially arranged in the mixing cavity of the nozzle. From the feed port to the discharge pipe, the volume of its thread groove gradually decreases and the screw diameter gradually increases, forming a progressive compression channel. The ultrasonic vibrator is arranged around the outer side of the mixing cavity of the nozzle.

[0019] In some embodiments, the gap between the threads of the mixing extrusion variable diameter screw and the inner wall of the mixing cavity of the nozzle is less than 0.1 mm.

[0020] The screw taper of the mixing extrusion variable diameter screw is 0.08-0.1.

[0021] The discharge end of the mixing cavity of the nozzle is connected to the discharge pipe through a conical diameter reduction structure, and the discharge end of the mixing extrusion variable diameter screw is provided with a diameter reduction structure matched therewith.

[0022] The variable-diameter screw (with gradually decreasing screw grooves) increases the flow space for slurry at the upper end. The feed end adopts a design with minimum screw diameter and maximum screw groove depth. Through negative pressure adsorption, it achieves stable introduction of high-viscosity, high-solid content slurry, effectively eliminating the problems of insufficient feeding and material slippage in conventional constant-diameter screws.

[0023] Enhanced degassing and exhaust capabilities provide more stable extrusion pressure and reduce extrusion volume changes caused by pressure fluctuations.

[0024] If the discharge end of a variable diameter screw is flat, the resulting right-angle step creates a Karman vortex street, causing material retention. Providing a matching reduced diameter structure at the discharge end of the variable diameter screw effectively eliminates the dead zone and reduces the amount of material residue.

[0025] In addition, setting the discharge end of the variable diameter screw to a reduced diameter structure can also help improve printing accuracy and is more suitable for the smooth extrusion of high-viscosity materials.

[0026] The ultrasonic vibrator is a common ultrasonic vibrator: a piezoelectric ceramic ring, an electrode sheet and a metal end cover; the installation method is: brazing installation.

[0027] In some embodiments, the discharge pipe is arranged at the discharge end of the mixing cavity of the nozzle, and the outer side of the discharge pipe is wound with an electromagnetic heating coil.

[0028] During 3D printing, electromagnetic heating coils induce eddy current heating inside the material through a high-frequency alternating magnetic field, achieving precise and efficient material softening. This ensures the smooth flow of mixed materials and further reduces material residue.

[0029] In some embodiments, the number of the feed ports is at least two.

[0030] Preferably, the feed inlet, the cleaning liquid inlet and the hot air inlet are evenly distributed in an annular shape.

[0031] In a second aspect, the present invention provides a multi-material 3D printing method with a self-cleaning function, comprising the following steps: The printing material is injected into the mixing cavity of the nozzle through the feed port, and the material is progressively compressed and mixed and extruded using a mixing extrusion variable diameter screw. At the same time, an ultrasonic vibrator is used to apply ultrasound to the mixing cavity of the nozzle to promote mixing; After printing is completed, when cleaning is required, the cleaning liquid is introduced into the mixing cavity of the nozzle through the cleaning liquid inlet, and ultrasonic cleaning is applied.

[0032] In some embodiments, the method further includes subjecting the mixed material to electromagnetic heating and softening at the discharge pipe.

[0033] The present invention will be further described below with reference to the embodiments.

[0034] like Figure 1 As shown, a multi-material 3D printing nozzle with self-cleaning function mainly consists of a nozzle body, a material delivery system, a self-cleaning system, a temperature control system and a control system.

[0035] The printer frame 1 includes an X-axis motion module 2, a Y-axis motion module 4 and a Z-axis motion module 3. A printing platform 5 is also provided on the printer frame 1. The nozzle is fixed on the X-axis motion module 2 through an X-axis fixture 6 and a nozzle fixing plate 7.

[0036] like Figure 2 and Figure 3 As shown, the print head includes a motor 8001, a nozzle mixing cavity, a mixing extrusion variable diameter screw 8007, a discharge pipe and an ultrasonic vibrator 8003, wherein: The mixing cavity of the nozzle is a cylindrical structure, and its end is provided with a feed port 8008, a cleaning liquid inlet and a hot air inlet; The end of the mixing extrusion variable diameter screw 8007 is connected to the motor 8001. Its main body is axially arranged in the mixing cavity of the nozzle. From the feed port to the discharge pipe, the volume of its thread groove gradually decreases and the screw diameter gradually increases, forming a progressive compression channel. The ultrasonic vibrator 8003 is arranged around the outside of the nozzle mixing cavity.

[0037] The gap between the threads of the mixing and extruding variable diameter screw 8007 and the inner wall of the mixing cavity of the nozzle is less than 0.1 mm. The screw taper of the mixing and extruding variable diameter screw 8007 is 0.08-0.1.

[0038] The discharge pipe is arranged at the discharge end of the nozzle mixing cavity, and the outer side of the discharge pipe is wound with the electromagnetic heating coil 8005. The number of the feed ports is at least two. The feed port, the cleaning liquid inlet and the hot air inlet are evenly distributed in an annular manner, such as Figure 4 shown.

[0039] The nozzle body is made of high-strength, corrosion-resistant materials, with an internal material flow channel. Different printing materials are mixed and extruded through the variable-diameter mixing screw 8007. An electromagnetic heating coil is designed at the nozzle outlet to assist in material extrusion, allowing multiple materials to be evenly mixed or distributed according to a preset pattern during extrusion to meet different printing needs.

[0040] The material delivery system consists of multiple barrels, delivery pipes, and a screw extruder module. Each barrel is used to store a different printing material. The delivery pipes connect the barrels to the flow path of the printhead body. A stepper motor precisely controls the delivery speed and flow rate of each material, ensuring stable and accurate material delivery to the printhead.

[0041] The self-cleaning system includes a cleaning liquid storage tank, a cleaning liquid delivery pipeline, ultrasonic-assisted cleaning equipment, and hot air delivery and drying equipment. The cleaning liquid storage tank stores a specially configured cleaning liquid. The cleaning liquid delivery pipeline delivers the cleaning liquid from the storage tank to the nozzle cavity, and the delivery of the cleaning liquid is controlled by a solenoid valve. The ultrasonic vibrator assists in cleaning and slurry extrusion. During operation, ultrasound is used to assist in cleaning the proximal extrusion device cavity, preventing material contamination after changing between different materials.

[0042] Temperature Control System: Temperature sensors and heating elements are installed in the nozzle's flow path and at the nozzle outlet. The temperature sensor monitors the material's temperature in real time, while the heating element heats or insulates the material according to the control system's instructions, ensuring that the material is extruded at the appropriate temperature. This reduces viscosity, improves fluidity, and reduces the risk of clogging. The temperature control system also precisely controls the nozzle's overall temperature, preventing problems such as uneven curing or nozzle deformation caused by temperature fluctuations.

[0043] The control system, the core of the entire printhead, receives feedback from multiple sensors, including temperature and pressure sensors, and comprehensively regulates the operating parameters of the material delivery system, self-cleaning system, and temperature control system. Based on the preset print model and material characteristics, the control system precisely controls the speed of the stepper motor to advance the cleaning fluid and slurry, the power of the heating element, and the operation of the hot air drying device, thus automating and precisely controlling the multi-material 3D printing process and ensuring that the printhead remains in optimal working condition throughout the printing process.

[0044] The cleaning liquid in the cleaning liquid storage tank is a special material dissolving liquid that can quickly dissolve various materials remaining during the printing process and has no corrosive effect on the nozzle body and internal structure.

[0045] The ventilation duct of the drying device is made of high-temperature resistant materials, such as silica gel, which not only has the function of high-temperature resistance but also can realize remote air supply.

[0046] The temperature control system has a temperature control range of 20-300℃.

[0047] Before printing, [S1] adjusts the X, Y, and Z axes, activates the electromagnetic heating coil 8005 to heat the nozzle 8004, and activates the 42° stepper motor 8001 to rotate the mixing and extrusion variable diameter screw 8007. [S2] Moves to the cleaning tank, introduces cleaning fluid into the nozzle cavity through the cleaning fluid inlet 80081, activates the ultrasonic generator, and causes the ultrasonic vibrator 8003 to clean the interior of the flow channel. After cleaning is complete, the ultrasonic generator is turned off to stop the ultrasonic vibrator 8003. After the cleaning fluid is removed, 80°C hot air is introduced through the hot air inlet 80083 to dry the flow channel cavity. Once drying is complete, the hot air generator is turned off.

[0048] Printing process [S3] Obtain the G-code file and import it into the printing device. Use CAD software to build the required three-dimensional part model, import the three-dimensional part model into the layering software, set the 3D printing process parameters in the layering software, generate a G-code file, and import the G-code file into the direct-write 3D printing device; optional CAD software includes Solidworks, ProE, UG and other three-dimensional modeling software; the three-dimensional part model imported into the layering software needs to be saved in STL format; optional layering software includes PrusaSlicer, BCN3D Cura, PreForm and other layering software; the 3D printing process parameters set in the layering software include: the vertical adjustment mechanism's starting point height, layer height, nozzle movement speed, extrusion speed, and the materials selected for different areas; the vertical adjustment mechanism's starting point height is obtained in step S1, and the layer height, nozzle movement speed, and extrusion speed are selected based on experience according to the type of slurry material; import the G-code file into the SD card, insert the SD card into the SD card slot of the direct-write 3D printing device, and import the G-code file into the direct-write 3D printing device.

[0049] [S4] performs single-layer printing, [S41] starts the 42 stepper motor 42 stepper motor 8001 to drive the mixed extrusion variable diameter screw 8007 to rotate, turns on the electromagnetic induction heating coil switch, starts the feeding system to deliver metal slurry, ceramic slurry or metal / ceramic slurry to the inner cavity through the first feed port 80082 and the second feed port 80084, and after delivering the slurry to the inner cavity for a certain period of time, starts the ultrasonic generator switch.

[0050] When only the same type of slurry with the same components is conveyed: the 42-step motor 8001 drives the mixed extrusion variable diameter screw 8007 to shear the slurry in the inner cavity of the nozzle. According to the non-Newtonian fluid characteristics of the slurry, the viscosity decreases under the shear of the variable diameter screw 8007, and the greater the shear force is, the lower the viscosity is, and the easier it is to extrude. At the same time, the ultrasonic generator drives the ultrasonic vibrator through the main board to generate transverse waves in the flow direction of the fluid in the flow channel, which promotes the slurry to be extruded downward more easily and removes the air inside the slurry.

[0051] When conveying different slurries or different components of a slurry: 42 stepper motors 8001 drive the mixing and extrusion variable diameter screw 8007. For the slurry conveyed from feed port No. 1 80082 and feed port No. 2 80084 to the inner cavity of the nozzle, it is extruded downward due to the variable diameter, and the extrusion force becomes greater the further downward it is. According to the non-Newtonian fluid properties of the slurry, the viscosity decreases under the shear of the variable diameter screw 8007, and the shear force becomes greater the further downward it is, the lower the viscosity becomes, and the easier it is to extrude. At the same time, the rotating shearing and stirring of the screw makes the slurry more evenly mixed; at the same time, the ultrasonic generator drives the ultrasonic vibrator through the mainboard to work, generating transverse waves with respect to the flow direction of the fluid in the flow channel. Due to the action of the vibration wave, the different slurries inside begin to mix together, further obtaining a uniformly mixed slurry, promoting easier downward extrusion of the slurry, and removing the air inside the slurry.

[0052] When the slurry reaches the nozzle, an electromagnetic induction coil heats it. The temperature can be set to a specific level based on the slurry's characteristics. A temperature sensor transmits temperature changes in real time, facilitating timely temperature adjustments. Heating by the electromagnetic induction coil effectively reduces the slurry's viscosity, making it easier to extrude from the nozzle. The nozzle forms a single layer on the print platform 5, following the set print path.

[0053] After printing a specific material, the ultrasonic system is turned off, the nozzle moves to the designated position, and preparations are made before changing the material. Step S2 is repeated for cleaning, and then step S41 is repeated. The nozzle completes single-layer printing according to the preset path.

[0054] [S5] Repeat step S4, and finally accumulate through layer-by-layer deposition to obtain a three-dimensional solid part intermediate with different materials in different regions of the same layer, different materials in different layers, and gradually changing gradient materials.

[0055] Advantages of the printing method: It can realize single-material and multi-material printing. The printed part intermediate can realize printing of different materials in different areas of a layer, printing of different materials in different layers, gradient printing of slurry mixtures, and various forms of gradient printing. Ultrasound is used to assist printing and cleaning, and pollution-free printing is achieved after drying. The heating of the electromagnetic induction coil, the transverse wave vibration of the ultrasonic vibrator, and the shearing of the variable diameter screw improve the 3D printing quality.

[0056] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A multi-material 3D printing nozzle with self-cleaning function, characterized by: It includes a motor, a nozzle mixing cavity, a mixing extrusion variable diameter screw, a discharge pipe and an ultrasonic vibrator, among which, The mixing cavity of the nozzle is a cylindrical structure, and a feed port, a cleaning liquid inlet and a hot air inlet are provided at its end; The end of the mixing extrusion variable diameter screw is connected to the motor, and its main body is axially arranged in the mixing cavity of the nozzle. From the feed port to the discharge pipe, the volume of its thread groove gradually decreases and the screw diameter gradually increases, forming a progressive compression channel. The ultrasonic vibrator is arranged around the outer side of the mixing cavity of the nozzle.

2. The multi-material 3D printing nozzle with self-cleaning function according to claim 1, characterized in that: The gap between the threads of the mixing extrusion variable-diameter screw and the inner wall of the mixing cavity of the nozzle is less than 0.1 mm.

3. The multi-material 3D printing nozzle with self-cleaning function according to claim 1, characterized in that: The screw taper of the mixing extrusion variable diameter screw is 0.08-0.

1.

4. The multi-material 3D printing nozzle with self-cleaning function according to claim 1, characterized in that: The screw taper of the mixing extrusion variable diameter screw is 0.

09.

5. The multi-material 3D printing nozzle with self-cleaning function according to claim 1, characterized in that: The discharge end of the mixing cavity of the nozzle is connected to the discharge pipe through a conical diameter reduction structure, and the discharge end of the mixing extrusion variable diameter screw is provided with a diameter reduction structure matched therewith.

6. The multi-material 3D printing nozzle with self-cleaning function according to claim 1, characterized in that: The discharge pipe is arranged at the discharge end of the mixing cavity of the nozzle, and the outer side of the discharge pipe is wound with an electromagnetic heating coil.

7. The multi-material 3D printing nozzle with self-cleaning function according to claim 1, characterized in that: The number of the feed ports is at least two.

8. The multi-material 3D printing nozzle with self-cleaning function according to claim 7, characterized in that: The feed inlet, cleaning liquid inlet and hot air inlet are evenly distributed in a ring.

9. A multi-material 3D printing method with self-cleaning function, characterized by: The method comprises the following steps: printing using the multi-material 3D printing nozzle with self-cleaning function according to any one of claims 1 to 8: The printing material is injected into the mixing cavity of the nozzle through the feed port, and the material is progressively compressed and mixed and extruded using a mixing extrusion variable diameter screw. At the same time, an ultrasonic vibrator is used to apply ultrasound to the mixing cavity of the nozzle to promote mixing; After printing is completed, when cleaning is required, the cleaning liquid is introduced into the mixing cavity of the nozzle through the cleaning liquid inlet, and ultrasonic cleaning is applied.

10. The multi-material 3D printing method with self-cleaning function according to claim 9, characterized in that: The method also includes the step of performing electromagnetic heating and softening on the mixed material at the discharge pipe.

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