Shear-assisted 3d printing extrusion device for high viscosity fluids and methods of use

Abstract

The application provides a shearing-assisted 3D printing extrusion device suitable for high-viscosity fluids and a use method, and a rotatable shearing device is arranged at a material inlet part of the device. The device generates radial or rotational shearing force during material feeding, can effectively apply shearing force to the material (especially shear-thinning material), increase the flowability of the material, disturb the surface of the material, destroy the adhesion layer of the material, reduce the interfacial adhesion resistance, and thus significantly improve the feeding efficiency and flow continuity of the high-viscosity fluid. The structure is simple in design, stable in operation and low in energy consumption, does not need to additionally arrange a mixing mechanism or a complex channel, can effectively solve the problems of difficult feeding of high-viscosity fluid and serious wall sticking, and has good popularization and application value.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing of high-viscosity fluid materials, and in particular to a 3D printing extrusion device suitable for high-viscosity fluids and a method for using the same. Background Art

[0002] With the rapid development of additive manufacturing technology, high-viscosity non-Newtonian fluids with significant shear-thinning properties—especially cement-based 3D printing slurries, bio-based / natural fiber-reinforced slurries, as well as silicones, paste resins, polymer gels, etc.—are being widely used in the fields of rapid prototyping of building components, flexible electronics, and personalized biomedical scaffolds due to their excellent mechanical properties, self-supporting forming capabilities, and functional adjustability. However, in the low-shear zone of the printing device (feeding and feeding stages), such slurries have extremely high viscosity and strong adhesion, and often cause wall sticking, accumulation, flocculation, and blockage at the print head hopper and the extruder inlet. If the extrusion system cannot apply sufficient shear to trigger its shear-thinning behavior, it will lead to flow interruption, broken filaments in the print, or discontinuity between layers, seriously weakening the stability and continuity of the printing process. The main problems are as follows:

[0003] 1. Limitations of traditional feeding structure

[0004] Currently, most 3D printing equipment uses a fixed feed channel. High-viscosity materials are prone to the following problems during delivery:

[0005] 1) Adhesion to pipe wall, accumulation and blockage: Due to the high viscosity and strong adhesion of the material, it is easy to form a retention layer at the feed port, the inner wall of the hopper or the pipe wall, resulting in poor feeding or even complete blockage.

[0006] 2) High-pressure feeding and a sharp increase in energy consumption: High-viscosity fluids tend to stick to the wall, resulting in poor feeding and inability to achieve stable and continuous feeding. Because the traditional feeding structure is only a static channel structure and does not exert effective shear force on the material, when faced with high-viscosity, highly adhesive materials, the material tends to adhere and accumulate at the feed port or on the pipe wall, causing blockage or interruption of feeding. This problem is a fundamental obstacle to the efficiency and stability of high-viscosity fluid printing. To force high-viscosity fluids into the extrusion system, existing technologies often use booster pumps or mechanical propulsion to achieve forced feeding. This solution significantly increases the system's energy consumption.

[0007] To force high-viscosity fluids into the extrusion system, either a booster pump or mechanical propulsion requires the extrusion system to operate under high pressure. This places higher demands on the equipment's sealing, pressure resistance, and operational safety, leading to complex systems, frequent maintenance, and high operating costs.

[0008] 3) Unstable extrusion and poor printing quality: Due to the accumulation and intermittent feeding in the feeding stage, the extrusion rate is difficult to maintain a stable state, which can easily lead to problems such as material breakage and uneven material deposition during the printing process, thus affecting the consistency of the printed structure, the interlayer bonding quality and the mechanical properties of the final product.

[0009] 2. Deficiencies of existing improvement solutions

[0010] To improve the fluidity of high-viscosity materials, existing technologies mainly use the following methods, but they still have significant shortcomings:

[0011] (1) Vibration-assisted unloading

[0012] Disadvantage 1: Reduced printing accuracy

[0013] While vibratory feeding can promote the flow of high-viscosity fluids to a certain extent, it lacks sufficient shear force to fundamentally address the problems of sticking to the wall and poor feeding, and can also introduce additional negative impacts. Vibration is directly transmitted from the extrusion system to the print head, causing a whip effect that can lead to stronger nozzle displacement or high-frequency vibrations, reducing the positioning accuracy of the print path, resulting in interlayer misalignment and reduced print surface quality.

[0014] Disadvantage 2: Shortened mechanical life and increased structural complexity

[0015] Continuous or high-frequency vibrations can loosen connecting components, damage the overall structural rigidity of the printhead, shorten the life of the device, and further reduce printing accuracy. Typical failure rates can increase by over 40% (measured data).

[0016] In addition, in order to achieve effective vibration transmission, the vibration blanking equipment needs to add an additional vibration excitation mechanism, which not only takes up equipment space, but also brings about problems of increased energy consumption and increased maintenance complexity.

[0017] (2) Giant mixing blade design (e.g. CN202210418728, a building concrete 3D printing head and 3D printer)

[0018] Disadvantage 1: bulky structure

[0019] The use of giant stirring blades 15 to increase the shearing force results in a complex structure. The giant stirring blades are difficult to disassemble and clean, and occupy the effective volume of the hopper.

[0020] Disadvantage 2: High drive energy consumption

[0021] Driving the giant stirring blade requires a high-power motor (usually >500W), which greatly increases the energy consumption of the print head.

[0022] Existing technologies have failed to fundamentally solve the contradiction between low-shear feeding and stable extrusion of high-viscosity materials. Therefore, there is an urgent need for a shear-assisted extrusion device suitable for 3D printing of high-viscosity fluids to solve key technical problems in existing technologies such as low feeding efficiency, discontinuous extrusion, and easy adhesion and clogging of high-viscosity fluids. Summary of the Invention

[0023] The purpose of the present invention is to provide a printing extrusion device that solves key technical problems such as low feeding efficiency, discontinuous extrusion, and easy adhesion and clogging of high-viscosity fluids, specifically a 3D printing shear-assisted extrusion device suitable for high-viscosity fluids and its use method.

[0024] In order to achieve the above object, the present invention adopts the following technical solutions:

[0025] A shear-assisted 3D printing extrusion device suitable for high-viscosity fluids, comprising a support frame, a hopper assembly, a stirring and shearing device, a power device, a transmission device, and a screw extruder;

[0026] The support frame is a rigid structure arranged outside the hopper assembly and the transmission device, and is connected to the screw extruder at the bottom for support and connection;

[0027] The hopper assembly includes an upper hopper and a lower hopper connected coaxially, the top of the upper hopper is connected to a feeding device arranged on the top of the support frame; a stirring and shearing device is arranged in the lower hopper, and an opening is provided on one side of the lower hopper, and the bottom of the lower hopper is connected to a screw extruder;

[0028] The power device includes a servo motor 1 and a servo motor 2 fixed to the top of the support frame, and is used to output power;

[0029] The stirring and shearing device comprises three groups of rotating discs coaxially arranged from top to bottom, the three groups of rotating discs being slidably embedded in the lower hopper through three-layer slide mechanisms respectively, and each group of rotating discs being radially connected to multiple groups of baffles as stirring elements;

[0030] The transmission device is arranged at the opening of the lower hopper and is used for transmission connection with the three groups of the turntables. The output shaft of the second servo motor is connected to the transmission device through the main shaft. The transmission device is combined with the reversing assembly to drive the adjacent turntables to generate rotational motion in opposite directions, forming a heterogeneous shear flow field.

[0031] The screw extruder is fixed at the bottom of the support frame and includes a sleeve and a main screw. One end of the main screw is connected to the output shaft of a servo motor, and the other end passes through the hopper assembly and extends into the sleeve.

[0032] Preferably, the support frame includes an upper fixed plate, a lower fixed plate and fixed columns; the fixed columns are at least four and evenly distributed between the upper fixed plate and the lower fixed plate to provide space for placing the hopper assembly and the transmission device;

[0033] The feeding device is arranged on the top of the upper fixed plate and is connected to the upper hopper. The servo motor 1 and the servo motor 2 are fixed on the top of the upper fixed plate. The output shaft of the servo motor 1 is connected to the main screw and passes through the hopper assembly and then extends into the sleeve. The output shaft of the servo motor 2 passes through the main shaft and passes through the transmission device, and the bearing is installed on the lower fixed plate.

[0034] The bottom of the lower fixed plate is connected to a sleeve via screws, and the sleeve is communicated with the lower hopper.

[0035] Preferably, a partially nested and overlapping design is adopted between the three groups of turntables and their upper and lower adjacent structures, that is, the lower edge of the upper turntable covers the upper edge of the middle turntable, and the lower edge of the middle turntable covers the upper edge of the lower turntable, forming a stepped shielding area, which is used to prevent the fluid from infiltrating into the transmission mechanism due to inertial splashing during the shearing process, thereby extending the service life of the gear system and bearing components and improving maintenance convenience.

[0036] Preferably, the transmission device includes, from top to bottom, a coaxially arranged upper drive gear, a middle drive gear, a lower drive gear and a main shaft. The axes of the upper drive gear, the middle drive gear and the lower drive gear are respectively connected to the main shaft through flat keys, so that the upper drive gear, the middle drive gear and the lower drive gear are coaxially connected in series on the main shaft. The main shaft is driven to rotate by servo motor 2, thereby driving the upper drive gear, the middle drive gear and the lower drive gear to rotate in the same direction.

[0037] Preferably, the three groups of turntables include, from top to bottom, an upper turntable, a middle turntable and a lower turntable, and the upper turntable, the middle turntable and the lower turntable are slidably embedded in the lower hopper from top to bottom through a slide mechanism; the inner rings of the upper turntable, the middle turntable and the lower turntable are radially connected to the upper baffle, the middle baffle and the lower baffle, respectively, and are located in the lower hopper;

[0038] The upper turntable is engaged with the upper drive gear, the middle turntable is connected to the reversing assembly, the reversing assembly is connected to the middle drive gear, and the lower turntable is engaged with the lower drive gear; the upper turntable and the lower turntable are driven to rotate in the same direction by the upper drive gear and the lower drive gear, and the middle drive gear drives the middle turntable to rotate in different directions through the reversing assembly, thereby realizing the reverse rotation of adjacent turntables, driving the corresponding upper baffles, middle baffles and lower baffles to form disturbances in staggered directions in the lower hopper, so that the fluid located at the junction of the three groups of turntables is subjected to shear forces in opposite directions, promoting the dispersion, mixing and homogenization of high-viscosity fluids, thereby improving their fluidity.

[0039] Preferably, the lower hopper adopts a conical cylinder with a larger upper portion and a smaller lower portion, and three groups of turntables are provided and are sequentially embedded in the conical cylinder with sizes from large to small from top to bottom.

[0040] Preferably, adjacent turntables in the three groups of turntables are nested and overlapped, and the nested and overlapped arrangement includes the lower edge of the upper turntable covering the upper edge of the middle turntable, and the lower edge of the middle turntable covering the upper edge of the lower turntable, forming a stepped shielding area. The overall structure is an imbricate structure, which is used to prevent fluids, moisture impurities from infiltrating into the transmission mechanism due to inertial splashing during the shearing process, thereby extending the service life of the gear system and bearing components and improving the convenience of maintenance.

[0041] Preferably, the slide mechanism is arranged in the lower hopper, and includes three layers of annular slides, each for mounting three groups of turntables. The two sides of the three groups of turntables are respectively provided with a groove 1 and a groove 2, wherein the groove 1 is vertically grooved and the groove 2 is inner obliquely grooved.

[0042] The annular slideway on each layer includes a raised slideway 1 and a raised slideway 2, wherein the raised slideway 1 adopts a vertical raised structure, and the raised slideway 2 adopts an inclined raised structure;

[0043] The turntable is respectively plugged into the raised slideway 1 of the annular slideway through groove 1 to resist normal pressure, and the groove 2 is respectively plugged into the raised slideway 2 to resist torque caused by internal forces. The three groups of turntables are constrained in their planar rotation through three layers of annular slideways, thereby improving the stability of the turntable during axial rotation.

[0044] Preferably, the reversing assembly includes a lateral support fixture and a middle-layer transmission gear;

[0045] One side of the middle transmission gear is engaged with the middle turntable to provide transmission force, and the other side of the middle transmission gear is engaged with the middle drive gear to receive transmission force;

[0046] The main shaft passes through the transverse support clamp, and the transverse support clamp includes an upper clamp and a lower clamp, which are respectively fixed at the opening of the lower hopper, and the middle-layer transmission gear and the middle-layer drive gear that mesh with each other are located between the upper clamp and the lower clamp and leave a rotation gap. The upper clamp and the lower clamp are connected to the middle-layer transmission gear through independent bearings to avoid interference with the main shaft.

[0047] Preferably, the feeding device includes a plastic feed port arranged on the top of the upper fixed plate and connected to the upper hopper. The plastic feed port is provided with a threaded pressure cap or a locking ring to ensure that the interface is sealed and connected to a feed hose for introducing high viscosity fluid.

[0048] The present invention also provides a method for using a shear-assisted 3D printing extrusion device for high-viscosity fluids, comprising the following steps:

[0049] Step S1: Preparation:

[0050] Before printing, high-viscosity fluids such as bio-based or cement-based printing slurries are pre-treated through an external feeding system and then delivered to the plastic feed port via a polyurethane feed hose. The raw materials further flow into the upper hopper and flow into the lower hopper under the action of gravity, providing a stable raw material for subsequent mixing.

[0051] Step S2: Shear Mixing Start:

[0052] Start the second servo motor in the power device, which drives the main shaft to rotate. The main shaft drives the upper drive gear, middle drive gear and lower drive gear installed at different heights to rotate in sequence, thereby driving the synchronous rotation of the upper turntable, middle turntable and lower turntable.

[0053] Among them, the upper driving gear and the middle driving gear are engaged with the upper turntable and the lower turntable respectively, and drive the upper turntable and the lower turntable to rotate in the same direction;

[0054] The middle driving gear is meshed with one side of the middle transmission gear of the reversing assembly, and the other side of the middle transmission gear is meshed with the middle turntable to transmit power. The rotation of the middle driving gear drives the middle transmission gear to rotate, and the middle transmission gear drives the middle turntable to rotate in the opposite direction, that is, the rotation direction of the middle turntable is opposite to that of the upper turntable and the lower turntable, realizing the reverse rotation of adjacent turntables, thereby driving the upper baffles, middle baffles and lower baffles corresponding to the three groups of turntables to form staggered disturbances in the lower hopper, promoting the dispersion, mixing and homogenization of high-viscosity fluids;

[0055] Servo motor 1 is activated synchronously, driving the main screw. The main screw is a through-shaft structure that runs through the entire hopper assembly from top to bottom, terminating in a stainless steel sleeve. High-viscosity fluid is continuously pushed into the sleeve through the bottom outlet. The main screw steadily and evenly propels the fluid, achieving quantitative extrusion of the high-viscosity mixture. Servo motor 1's speed is adjustable from 0–80 rpm, allowing the extrusion rate to be matched to the print speed in real time. The extruded mixture is deposited directly onto the build platform through the nozzle at the end, completing the layer-by-layer deposition process.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] 1. Traditional high-pressure feeding solutions consume a lot of energy and carry heavy loads. However, the present invention utilizes a multi-layered shear disc structure to fully disturb and pre-treat the material before it enters the extrusion channel. Compared to overcoming viscous resistance through pressurization or forced pumping, the present invention utilizes multi-stage counter-rotating shear discs to apply effective shear force to the material, weakening its flow viscosity in localized areas. This significantly reduces the system's reliance on pumping pressure, fundamentally reducing energy consumption and motor load, effectively alleviating equipment operating pressure and improving system energy efficiency.

[0058] 2. High-viscosity fluids in existing technologies tend to stick to walls and accumulate during printing, causing blockages. The present invention achieves a shear-assisted extrusion mode that simultaneously feeds and stirs the material through structural innovation. Multiple turntables within the lower layer 22 of the hopper rotate in opposite directions, continuously applying disturbing and shearing forces to the material during the feeding process. This prevents the formation of stagnant areas on walls or in corners, effectively preventing the accumulation and blockage common in traditional channels and enabling stable and continuous feeding of high-viscosity fluids at low pressure.

[0059] 3. Traditional systems operate at high pressure, resulting in complex equipment and frequent maintenance. The present invention eliminates the high-pressure pump and complex boost module. All shearing, disturbance, and extrusion functions are performed through an integrated drive structure. The main drive shaft 15 is connected in series with three sets of drive gears, achieving multi-layer shear force output through simple mechanical linkage. This results in a compact structure, highly versatile components, and easy maintenance and replacement, significantly improving system reliability and reducing operating costs.

[0060] 4. While existing vibrating blanking mechanisms reduce print path accuracy and mechanical life, this invention completely eliminates excitation elements and instead achieves efficient blanking through structured shearing. The shearing disturbance of the turntable acts only on the internal material flow field, without causing mechanical impact or micro-vibration to the entire printhead. This significantly improves print path stability and inter-layer alignment accuracy, ensuring the surface quality and geometric consistency of the printed product. Furthermore, the entire transmission mechanism is equipped with bearings and rigid positioning structures, making it suitable for long-term continuous operation and thus extending the life of the entire machine.

[0061] 5. The present invention innovatively designs a multi-ring shearing mechanism, and at the same time, through the "shingled" design between adjacent turntables, blocks the fluid from entering the transmission mechanism, thereby ensuring the tightness of the complex structure in the print head. Specifically, the three groups of turntables and their upper and lower adjacent structures adopt a partially nested overlapping design, that is, the lower edge of the upper turntable covers the upper edge of the middle turntable, and the lower edge of the middle turntable (24) covers the upper edge of the lower turntable, forming a stepped shielding area ("shingled" structure), which is used to block impurities such as fluid and moisture from infiltrating into the transmission mechanism due to inertial splashing during the shearing process, thereby extending the service life of the gear system and bearing components and improving maintenance convenience. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 Schematic diagram of the three-dimensional structure of a shear-assisted 3D printing extrusion device suitable for high-viscosity fluids provided by an embodiment of the present invention Figure 1 ;

[0063] Figure 2 Schematic diagram of the three-dimensional structure of a shear-assisted 3D printing extrusion device suitable for high-viscosity fluids provided by an embodiment of the present invention Figure 2 ;

[0064] Figure 3 Schematic diagram of the three-dimensional structure of a shear-assisted 3D printing extrusion device suitable for high-viscosity fluids provided by an embodiment of the present invention Figure 3 ;

[0065] Figure 4 A schematic front view of a shear-assisted 3D printing extrusion device suitable for high-viscosity fluids provided by an embodiment of the present invention;

[0066] Figure 5 for Figure 4 Schematic diagram of the cross-sectional structure;

[0067] Figure 6 for Figure 5 Schematic diagram of a local enlarged structure;

[0068] Figure 7 A schematic diagram of the structure of a lower hopper in a shear-assisted 3D printing extrusion device suitable for high-viscosity fluids provided by an embodiment of the present invention;

[0069] Figure 8 Schematic diagram of the structure of a turntable in a shear-assisted 3D printing extrusion device suitable for high-viscosity fluids provided by an embodiment of the present invention Figure 1 ;

[0070] Figure 9 Schematic diagram of the structure of a turntable in a shear-assisted 3D printing extrusion device suitable for high-viscosity fluids provided by an embodiment of the present invention Figure 2 ;

[0071] Figure 10 A schematic side view of the turntable provided in an embodiment of the present invention;

[0072] Figure 11 A schematic diagram of the three-dimensional structure of the nested relationship of three groups of turntables provided in an embodiment of the present invention;

[0073] Figure 12 A partial cross-sectional enlarged structural schematic diagram of the nested relationship of three groups of turntables provided in an embodiment of the present invention.

[0074] The serial numbers in the figure are as follows:

[0075] 1. Mixing and shearing device; 2. Power device; 3. Transmission device; 4. Screw extruder; 5. Upper fixed plate; 6. Lower fixed plate; 7. Fixed column; 8. Upper baffle; 9. Middle baffle; 10. Servo motor 1; 11. Servo motor 2; 12. Robot arm connector; 13. Lower baffle; 14. Sleeve; 15. Spindle; 16. Upper fixture; 17. Main screw; 18. Lower fixture; 19. Feeding soft Tube; 20. Plastic feed port; 21. Upper hopper; 22. Lower hopper; 23. Upper turntable; 24. Middle turntable; 25. Lower turntable; 26. Upper drive gear; 27. Middle drive gear; 28. Middle transmission gear; 29. ​​Lower drive gear; 30. Raised slideway 1; 31. Raised slideway 2; 32. Flat key; 33. Groove 1; 34. Groove 2; 35. Upper edge; 36. Lower edge. DETAILED DESCRIPTION

[0076] The technical solutions 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 only part of the embodiments of the present invention, rather than all the embodiments.

[0077] like Figures 1 to 4 As shown, a shear-assisted 3D printing extrusion device suitable for high-viscosity fluids provided in this embodiment includes a support frame, a hopper assembly, a stirring and shearing device 1, a power device 2, a transmission device 3 and a screw extrusion device 4.

[0078] The support frame uses a rigid structure for support and connection, including an upper fixed plate 5, a lower fixed plate 6, and fixed columns 7. At least four fixed columns 7 are evenly distributed between the upper and lower fixed plates 5, 6, to provide space for the hopper assembly and transmission device 3. The bottom of the lower fixed plate 6 is screwed to the sleeve 14 of the screw extruder 4, and the sleeve 14 is connected to the lower hopper 22. A robotic arm connector 12 is connected between the upper and lower fixed plates 5, 6 for external connection to the robotic arm.

[0079] The feeding device includes a plastic feed port 20 arranged on the top of the upper fixed plate 5 and connected to the upper hopper 21. The lower end of the feed hose 19 is inserted into and connected to the plastic feed port 20. The top of the plastic feed port 20 is provided with a threaded pressure cap locking structure to ensure sealing. The bottom of the plastic feed port 20 leads to the interior of the upper hopper 21 for introducing high-viscosity fluid.

[0080] The hopper assembly adopts a two-stage design, including an upper hopper 21 and a lower hopper 22 that are coaxially connected. The top of the upper hopper 21 is fixed to the bottom of the upper fixed plate 5 and is connected to the plastic feed inlet 20; the lower hopper 22 is fixed to the top of the lower fixed plate 6. The lower hopper 22 adopts a 270° arc cylinder, in which a stirring and shearing device 1 is arranged, and an opening is provided on one side of the lower hopper 22. The bottom of the lower hopper 22 is connected to the screw extrusion device 4.

[0081] Furthermore, the upper hopper 21 and the lower hopper 22 are made of aluminum alloy CNC material, and the two are anchored by bolts.

[0082] Power unit 2, located above agitator and shear unit 1, comprises servo motor 10 and servo motor 2 11, secured to the top of upper fixed plate 5. Both motors 10 and 11 are anchored to upper fixed plate 5 via top contact points for power output. Cables are routed to the back of the unit for unified management within the integrated control system.

[0083] The output shaft of servo motor 10 is connected to the main screw 17, passes through the hopper assembly, and extends into the sleeve 14 to drive the high-viscosity fluid to be extruded; the output shaft of servo motor 2 11 passes through the main shaft 15, passes through the transmission device 3, and is installed on the lower fixed plate 6 through a bearing to provide power for the stirring and shearing device 1.

[0084] Furthermore, servo motor 10 and servo motor 2 11 utilize hollow servo motors. Compared to traditional motors, hollow servo motors are annular in shape and compact in structure, with a central cavity extending vertically through the motor. In this embodiment, the inner radius of servo motor 10 is larger than the outer diameter of the upper end of main screw 17, creating a moderate extrusion gap to minimize friction between hollow servo motor 10 and the outer wall of the main screw 17 during movement.

[0085] Furthermore, in this embodiment, the rotary interface between the servo motor 10 and the main screw 17 is equipped with a labyrinth dust cover or a light shaft seal ring to prevent material splashing or dust from entering the motor cavity, thereby extending the service life of the system. The hollow servo motor 10 supports a continuously adjustable speed of 0-80 rpm to meet the extrusion requirements of different material viscosities and printing rates. The hollow servo motor 2 11 is responsible for driving the operation of the entire stirring and shearing device 1, and its output shaft is connected to the main shaft 15 through an extended coupling. The main shaft 15 is a carbon steel through-type transmission shaft, the surface of which has been tempered and has good wear resistance and torsional strength. The main shaft is connected to the transmission device 3 composed of three sets of drive wheels from top to bottom, providing multi-level power output for the three-layer turntable in the stirring and shearing device 1.

[0086] The stirring and shearing device 1 comprises three groups of turntables coaxially arranged from top to bottom, and the transmission device 3 provides rotational power to drive the baffles corresponding to the three groups of turntables to rotate.

[0087] The three groups of turntables include, from top to bottom, an upper turntable 23, a middle turntable 24 and a lower turntable 25 made of high-strength POM material to form an annular shear element. The upper turntable 23, the middle turntable 24 and the lower turntable 25 are respectively slid from top to bottom through three layers of horizontal annular slides and embedded in the lower hopper 22; the inner rings of the upper turntable 23, the middle turntable 24 and the lower turntable 25 are respectively radially connected to the upper baffle 8, the middle baffle 9 and the lower baffle 13 as stirring elements, and are located in the lower hopper 22.

[0088] The upper turntable 23 is meshed with the upper drive gear 26, the middle turntable 24 is connected to the reversing assembly, the reversing assembly is connected to the middle drive gear 27, and the lower turntable 25 is meshed with the lower drive gear 29; the upper turntable 23 and the lower turntable 25 are driven to rotate in the same direction by the upper drive gear 26 and the lower drive gear 29, and the middle drive gear 27 drives the middle turntable 24 to rotate in the opposite direction through the reversing assembly, so that the rotation direction of the middle turntable 24 is the same as that of the upper turntable 23 and the lower turntable 25. The two adjacent turntables rotate in opposite directions, which can realize the reverse linkage of the three-layer shear turntable in a hopper assembly with limited space, and realize the reverse rotation of adjacent turntables. The overall structure is compact and the transmission is efficient, thereby driving the corresponding upper baffle 8, middle baffle 9 and lower baffle 13 to form a disturbance in the lower hopper 22 in an alternating direction, so that the fluid located at the junction of the three groups of turntables is subjected to shear forces in opposite directions, promoting the dispersion, mixing and homogenization of high-viscosity fluids, thereby improving their fluidity.

[0089] In this embodiment, three groups of turntables (i.e., an upper turntable 23, a middle turntable 24, and a lower turntable 25) are arranged in sequence along the vertical direction in the lower hopper 22. Each turntable is arranged in an axial plane and driven in conjunction with a servo motor through a gear transmission. Adjacent turntables rotate in opposite directions. When the material passes through the lower area of ​​the lower hopper 22, a strong shear layer is formed in the local area, causing the high-viscosity fluid to be disturbed continuously and in alternating directions during the flow process, effectively promoting dispersion, mixing, and homogenization. This structure achieves more sufficient shear treatment of the fluid through multi-layer coupled turntables rather than single-layer stirring, and is suitable for mixing processes of multi-component, high-viscosity fluids.

[0090] To further enhance the shearing effect, protrusions are provided on the inner wall of the lower hopper 22, corresponding to each of the three sets of rotating disks (i.e., upper baffles 8, middle baffles 9, and lower baffles 13). When adjacent rotating disks rotate in opposite directions, these protrusions create localized micro-turbulence zones and turbulence zones within the narrow channel, significantly increasing the local shear strength and dispersion of the fluid, thereby preventing stratification or uneven mixing of components.

[0091] In addition, if Figure 10 As shown, in this embodiment, the lower hopper 22 adopts a conical cylinder with a larger upper portion and a smaller lower portion. Based on the conical cylinder structure, three groups of turntables are arranged with sizes from large to small from top to bottom, that is, the size of the upper turntable 23 is larger than the middle turntable 24, and the middle turntable 24 is larger than the lower turntable 25. They are sequentially embedded in the conical cylinder through a slide mechanism.

[0092] Each turntable consists of a ring-shaped rotating gear with nested extension rings at the top and bottom. The top extension ring is larger than the bottom extension ring. To accommodate the conical structure of the lower hopper 22, the top and bottom extension rings are tilted relative to each other.

[0093] The edge of the extended ring adopts a stepped structure, the edge of the extended ring located at the top of the turntable is defined as the upper edge 35, and the edge of the extended ring located at the bottom of the turntable is defined as the lower edge 36. Figure 11 and Figure 12 As shown, adjacent turntables in the three groups are nested and overlapped. Specifically, the lower edge 36 of the extended ring at the bottom of the upper turntable 23 overlaps the upper edge 35 of the extended ring at the top of the middle turntable 24, and vice versa, forming a stepped shielding area. The overall structure is imbricate. Without affecting the rotational function, this structure effectively prevents fluid from infiltrating the transmission mechanism due to inertial splashing during shearing, thereby extending the service life of the gear system and bearing components. Compared to traditional fully enclosed or sealed cover designs, this nested and overlapped structure eliminates the need for additional seals, reducing manufacturing complexity and improving maintenance ease.

[0094] Furthermore, in this embodiment, Figures 7 to 9 As shown, the three groups of turntables are slidably embedded in the lower hopper 22 through three-layer slide mechanisms respectively. The lower hopper 22 serves as the installation base of the stirring and shearing device 1. The inner wall of the lower hopper 22 is provided with three layers of horizontal annular slides, which are used to install the three groups of turntables respectively. The two sides of the three groups of turntables are respectively provided with groove 1 33 and groove 2 34. Groove 1 33 adopts vertical grooves, and groove 2 34 adopts inner oblique grooves.

[0095] Each layer of the annular slideway consists of a raised slideway 1 30 and a raised slideway 2 31. Raised slideway 1 30 utilizes a vertically raised structure, while raised slideway 2 31 utilizes an inclined raised structure. The turntables engage with raised slideway 1 30 of the annular slideway via grooves 1 33 to resist normal pressure. Grooves 2 34 engage with raised slideway 2 31 to resist torque caused by internal forces. The three sets of turntables are constrained by the three layers of annular slideways to prevent planar rotation, thereby improving their stability during axial rotation.

[0096] like Figure 5 and Figure 6 As shown, the transmission device 3 is the core transmission structure that drives the stirring and shearing device. It is located between the power unit 2 and the stirring and shearing device 1. It is arranged on the side of the opening of the lower hopper 22 and is used for driving connection with the three sets of turntables. The output shaft of the servo motor 11 is connected in series with the transmission device 3 through the main shaft 15.

[0097] From top to bottom, the transmission device 3 comprises a coaxially arranged upper drive gear 26, a middle drive gear 27, and a lower drive gear 29, as well as a main shaft 15. The axes of the upper drive gear 26, middle drive gear 27, and lower drive gear 29 are connected to the main shaft 15 via flat keys 32, achieving a meshing accuracy of DIN 6. The upper drive gear 26, middle drive gear 27, and lower drive gear 29 are coaxially connected in series on the main shaft 15. The main shaft 15 is driven to rotate by the servo motor 2 11, which stably distributes the rotational motion of the servo motor 2 11 to the upper drive gear 26, middle drive gear 27, and lower drive gear 29 of the stirring and shearing device, achieving multi-layer rotary stirring and, in conjunction with the reversing assembly, a multi-directional shearing and stirring effect.

[0098] Because the transmission device 3 is fixed in a nested manner between the upper fixing plate 5 and the lower fixing plate 6, the transmission device 3 adopts an open layout, which is easy to maintain and clean. A lightweight protective cover can also be optionally installed to adapt to harsh conditions and prevent foreign matter from entering.

[0099] Furthermore, in this embodiment, the main shaft 15 is made of high-strength carbon steel, with a surface tempered to enhance its fatigue resistance. The upper end of the main shaft 15 is connected to the servo motor 2 11 via an extended coupling. The main shaft 15 is supported by bearings at three ends: the upper end passes through the upper fixed plate 5 and is positioned by an integrated bearing. The middle end passes through a transverse support fixture and is also equipped with an integrated bearing. The lower end passes through the lower fixed plate 6 and is equipped with a sealed bearing to ensure smooth rotation and high coaxiality.

[0100] The transmission device 3, in conjunction with a reversing assembly, drives adjacent rotating discs to generate opposite rotational motion, creating a counter-directional shear flow field. The reversing assembly includes a lateral support fixture and a middle-layer transmission gear 28. One side of the middle-layer transmission gear 28 engages with the middle-layer rotating disc 24 to provide transmission force, while the other side of the middle-layer transmission gear 28 engages with the middle-layer drive gear 27 to receive transmission force.

[0101] The main shaft 15 passes through the transverse support fixture, which includes an upper fixture 16 and a lower fixture 18, each anchored at the opening of the lower hopper 22, ensuring a tight connection between the turntable and the drive gear. The intermeshing middle transmission gear 28 and middle drive gear 27 are located between the upper fixture 16 and the lower fixture 18, with rotational clearance. The upper fixture 16 and the lower fixture 18 are connected to the middle transmission gear 28 via independent bearings to prevent interference with the main shaft 15.

[0102] The screw extruder 4 is located at the bottom of the entire system and is used to stably extrude the high-viscosity fluid after shear mixing. The screw extruder 4 includes a sleeve 14 and a main screw 17. The sleeve 14 is made of stainless steel and is coaxially fixed to the bottom of the lower fixed plate 6 by screws, forming a closed feeding structure.

[0103] The main screw 17 is a through-type structure, with its upper end connected to the motor output shaft via a rigid coupling. The surface of the main screw 17 is electropolished to reduce flow resistance. The screw diameter is φ20 mm, and the pitch and lead can be adjusted according to material properties, generally between 10-16 mm. One end of the main screw 17 is connected to the output shaft of servo motor 10, and the other end extends through the hopper assembly and into the sleeve 14.

[0104] This embodiment also provides a method for using a shear-assisted 3D printing extrusion device for high-viscosity fluids, comprising the following steps:

[0105] Step S1: Preparation:

[0106] Before printing, high-viscosity fluids such as bio-based printing slurry or cement-based printing slurry are pre-treated by an external feeding system and then delivered to the plastic feed port 20 via a polyurethane feed hose 19. The raw material further flows into the upper hopper 21 and, under the action of gravity, flows into the lower hopper 22, providing a stable raw material for subsequent mixing.

[0107] Step S2: Shear Mixing Start:

[0108] The servo motor 2 11 in the power device 2 is started, and the servo motor 2 11 drives the main shaft 15 to rotate. The main shaft 15 sequentially drives the upper drive gear 26, the middle drive gear 27 and the lower drive gear 29 installed at different heights to rotate, thereby driving the synchronous rotation of the upper turntable 23, the middle turntable 24 and the lower turntable 25;

[0109] Among them, the upper driving gear 26 and the middle driving gear 27 are respectively engaged with the upper turntable 23 and the lower turntable 25, and drive the upper turntable 23 and the lower turntable 25 to rotate in the same direction;

[0110] The middle-layer driving gear 27 is meshed with one side of the middle-layer transmission gear 28 of the reversing assembly, and the other side of the middle-layer transmission gear 28 is meshed with the middle-layer turntable 24 to transmit power. The rotation of the middle-layer driving gear 27 drives the middle-layer transmission gear 28 to rotate, so that the middle-layer transmission gear 28 indirectly transmits power to the middle-layer turntable 24 for counter-rotation, that is, the rotation direction of the middle-layer turntable 24 is opposite to that of the upper turntable 23 and the lower turntable 25, realizing the reverse rotation of adjacent turntables, forming a composite power diversion structure, and making the reduction ratio of the middle-layer turntable 24 higher.

[0111] This in turn drives the upper baffle 8, the middle baffle 9 and the lower baffle 13 corresponding to the three groups of turntables to form disturbances in staggered directions in the lower hopper 22, thereby promoting dispersion, mixing and homogenization of high-viscosity fluids.

[0112] Since the rotation direction of the middle turntable 24 is opposite to that of the upper and lower turntables, the higher reduction ratio of the middle turntable 24 is conducive to the reasonable distribution of torque, thereby increasing the shear force.

[0113] In addition, different speed ratios can be set by the control system to adapt to different viscosities and mixing requirements.

[0114] Servo motor 10 is activated synchronously, driving main screw 17. Main screw 17 is a through-shaft structure that extends from top to bottom through the entire hopper assembly, terminating in stainless steel sleeve 14. High-viscosity fluid is continuously pushed into sleeve 14 through the bottom outlet. Main screw 17 steadily and evenly propels the fluid, achieving quantitative extrusion of the high-viscosity mixture. Servo motor 10 offers adjustable speeds from 0–80 rpm, enabling real-time matching of the extrusion rate to the printing speed. The extruded mixture is deposited directly onto the build platform through the nozzle at the end, completing the layer-by-layer deposition process.

[0115] In summary, this embodiment sets a shear structure at the feed port, and applies shear disturbance to the material before it enters the extrusion mechanism through multiple rotatable and relatively reverse-moving annular shear elements, effectively destroying the boundary layer adhesion and improving the fluidity and uniformity during the feeding process. Compared with the existing method of forcibly pushing the material through a booster pump or a vibrating structure, the present invention solves the feeding bottleneck problem at the source in a low-energy manner through structural optimization, and has the advantages of stable operation, low equipment load, and simple control. At the same time, it avoids the problems of reduced printing accuracy and structural fatigue caused by high-frequency vibration. This embodiment is suitable for 3D printing processes that require high-viscosity fluids. It solves the problems of high-viscosity fluids sticking to the wall and poor extrusion before being fully stirred in traditional 3D printing processes; it significantly improves the feeding efficiency and flow stability of high-viscosity fluids, and avoids material accumulation and blockage problems; through this structural improvement, the system can achieve continuous and stable extrusion while ensuring mixing uniformity, further improving the reliability and printing quality of the high-viscosity fluid 3D printing process.

[0116] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying 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 should not be understood as limiting the present invention.

[0117] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0118] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A shear-assisted 3D printing extrusion device suitable for high-viscosity fluids, characterized in that: It comprises a supporting frame, a hopper assembly, a stirring and shearing device (1), a power device (2), a transmission device (3) and a screw extrusion device (4); The support frame is a rigid structure arranged outside the hopper assembly and the transmission device (3), and is connected to the screw extrusion device (4) at the bottom for support and connection; The hopper assembly comprises an upper hopper (21) and a lower hopper (22) that are coaxially connected, wherein the top of the upper hopper (21) is connected to a feeding device arranged on the top of a support frame; a stirring and shearing device (1) is arranged in the lower hopper (22), and an opening is provided on one side of the lower hopper (22); and the bottom of the lower hopper (22) is connected to a screw extrusion device (4); The power device (2) includes a servo motor 1 (10) and a servo motor 2 (11), which are used to output power; The stirring and shearing device (1) comprises three groups of rotating discs coaxially arranged from top to bottom, the three groups of rotating discs being slidably embedded in the lower hopper (22) through slide mechanisms respectively, and each group of rotating discs being radially connected to a plurality of baffles as stirring elements; The transmission device (3) is arranged at the opening of the lower hopper (22) and is used for transmission connection with the three groups of the turntables. The output shaft of the second servo motor (11) is connected to the transmission device (3) through the main shaft (15); the transmission device (3) is combined with the reversing component to drive the adjacent turntables to generate rotational motion in opposite directions, and through the multiple groups of baffles arranged on the turntables, the fluid material inside the lower hopper (22) is exerted with forces in opposite directions, thereby forming a heterogeneous shear flow field; The screw extruder (4) is fixed to the bottom of the support frame and comprises a sleeve (14) and a main screw (17). One end of the main screw (17) is connected to the output shaft of servo motor 1 (10), and the other end passes through the hopper assembly and extends into the sleeve (14).

2. A shear-assisted 3D printing extrusion device suitable for high-viscosity fluids according to claim 1, characterized in that: The support frame comprises an upper fixed plate (5), a lower fixed plate (6) and fixed columns (7); at least four fixed columns (7) are uniformly distributed between the upper fixed plate (5) and the lower fixed plate (6) to provide space for placing the hopper assembly and the transmission device (3); The feeding device is provided on the top of the upper fixed plate (5) and is connected to the upper hopper (21). The servo motor 1 (10) and the servo motor 2 (11) are fixed on the top of the upper fixed plate (5). The output shaft of the servo motor 1 (10) is connected to the main screw (17) and extends into the sleeve (14) after passing through the hopper assembly. The output shaft of the servo motor 2 (11) passes through the main shaft (15) and passes through the transmission device (3). The bearing is then installed on the lower fixed plate (6). The bottom of the lower fixed plate (6) is connected to a sleeve (14) via screws, and the sleeve (14) is communicated with the lower hopper (22).

3. A shear-assisted 3D printing extrusion device suitable for high-viscosity fluids according to claim 2, characterized in that: The transmission device (3) includes, from top to bottom, an upper driving gear (26), a middle driving gear (27) and a lower driving gear (29) arranged coaxially, and a main shaft (15). The axes of the upper driving gear (26), the middle driving gear (27) and the lower driving gear (29) are connected to the main shaft (15) through flat keys (32) respectively, so that the upper driving gear (26), the middle driving gear (27) and the lower driving gear (29) are coaxially connected in series on the main shaft (15). The main shaft (15) is driven to rotate by the servo motor 2 (11), thereby driving the upper driving gear (26), the middle driving gear (27) and the lower driving gear (29) to rotate in the same direction.

4. A shear-assisted 3D printing extrusion device suitable for high-viscosity fluids according to claim 3, characterized in that: The three groups of turntables include, from top to bottom, an upper turntable (23), a middle turntable (24), and a lower turntable (25), wherein the upper turntable (23), the middle turntable (24), and the lower turntable (25) are slidably embedded in the lower hopper (22) from top to bottom via a slide mechanism; the inner rings of the upper turntable (23), the middle turntable (24), and the lower turntable (25) are radially connected to the upper baffle (8), the middle baffle (9), and the lower baffle (13), respectively; The upper turntable (23) is meshed with the upper drive gear (26), the middle turntable (24) is connected to the reversing assembly, the reversing assembly is connected to the middle drive gear (27), and the lower turntable (25) is meshed with the lower drive gear (29); the upper turntable (23) and the lower turntable (25) are driven to rotate in the same direction by the upper drive gear (26) and the lower drive gear (29), and the middle drive gear (27) drives the middle turntable (24) to rotate in different directions through the reversing assembly, thereby realizing the reverse rotation of adjacent turntables, driving the corresponding upper baffle (8), middle baffle (9) and lower baffle (13) to form staggered direction movement in the lower hopper (22), so that the fluid located at the intersection of the three groups of turntables is subjected to shear forces in opposite directions, promoting the dispersion, mixing and homogenization of high-viscosity fluids, thereby improving their fluidity.

5. A shear-assisted 3D printing extrusion device suitable for high-viscosity fluids according to claim 4, characterized in that: The lower hopper (22) adopts a conical cylinder with a larger upper portion and a smaller lower portion, and three groups of turntables are provided, which are sequentially embedded in the conical cylinder in descending order of size from top to bottom.

6. A shear-assisted 3D printing extrusion device suitable for high-viscosity fluids according to claim 5, characterized in that: Adjacent turntables in the three groups of turntables are nested and overlapped, and the nested overlap includes the lower edge of the upper turntable (23) covering the upper edge of the middle turntable (24), and the lower edge of the middle turntable (24) covering the upper edge of the lower turntable (25), forming a stepped shielding area. The overall structure is an imbricate structure, which is used to prevent fluid, moisture and impurities from infiltrating into the transmission mechanism due to inertial splashing during the shearing process, thereby extending the service life of the gear system and bearing components and improving the convenience of maintenance.

7. A shear-assisted 3D printing extrusion device suitable for high-viscosity fluids according to claim 5, characterized in that: The slide mechanism is arranged in the lower hopper (22), and includes three layers of annular slides, each used to install three groups of turntables. The two sides of the three groups of turntables are respectively provided with groove 1 (33) and groove 2 (34). The groove 1 (33) is vertically grooved, and the groove 2 (34) is inner obliquely grooved. Each layer of the annular slide includes a raised slideway 1 (30) and a raised slideway 2 (31), wherein the raised slideway 1 (30) adopts a vertical raised structure, and the raised slideway 2 (31) adopts an inclined raised structure; The turntable is respectively connected to the raised slideway 1 (30) of the annular slideway through the groove 1 (33) to resist the normal pressure, and the groove 2 (34) is respectively connected to the raised slideway 2 (31) to resist the torque caused by the internal force. The three groups of turntables are constrained to rotate in the plane through the three layers of annular slideways, thereby improving the stability of the turntable during axial rotation.

8. A shear-assisted 3D printing extrusion device suitable for high-viscosity fluids according to claim 5, characterized in that: The reversing assembly includes a lateral support fixture and a middle transmission gear (28); One side of the middle-layer transmission gear (28) meshes with the middle-layer turntable (24) to provide transmission force, and the other side of the middle-layer transmission gear (28) meshes with the middle-layer drive gear (27) to receive transmission force; The main shaft (15) passes through the transverse support fixture, and the transverse support fixture includes an upper fixture (16) and a lower fixture (18), which are respectively fixed at the opening of the lower hopper (22), and the middle layer transmission gear (28) and the middle layer drive gear (27) that are meshed with each other are located between the upper fixture (16) and the lower fixture (18) and leave a rotation gap. The upper fixture (16) and the lower fixture (18) are connected to the middle layer transmission gear (28) through an independent bearing to avoid interference with the main shaft (15).

9. A shear-assisted 3D printing extrusion device suitable for high-viscosity fluids according to claim 8, characterized in that: The feeding device comprises a plastic feed port (20) arranged on the top of the upper fixed plate (5) and connected to the upper hopper (21); a threaded pressure cap or a locking ring is provided on the plastic feed port (20) to ensure that the interface is sealed and connected to a feed hose (19) for introducing high-viscosity fluid.

10. The method for using the shear-assisted 3D printing extruder for high-viscosity fluids according to claim 9, characterized in that: The steps include: Step S1: Preparation: Before printing, the high-viscosity fluid is pre-processed through an external feeding system and then transported to the plastic feed port (20) via a polyurethane feed hose (19); the raw material further flows into an upper hopper (21) and flows into a lower hopper (22) under the action of gravity, thereby preparing a stable raw material for subsequent mixing; Step S2: Shear Mixing Start: The servo motor 2 (11) in the power device (2) is started, and the servo motor 2 (11) drives the main shaft (15) to rotate, and the main shaft (15) sequentially drives the upper driving gear (26), the middle driving gear (27) and the lower driving gear (29) installed at different heights to rotate, thereby driving the upper turntable (23), the middle turntable (24) and the lower turntable (25) to rotate synchronously; The upper driving gear (26) and the middle driving gear (27) are respectively engaged with the upper rotating disc (23) and the lower rotating disc (25), and drive the upper rotating disc (23) and the lower rotating disc (25) to rotate in the same direction; The middle driving gear (27) is meshed with one side of the middle transmission gear (28) of the reversing assembly, and the other side of the middle transmission gear (28) is meshed with the middle turntable (24) to transmit power. The rotation of the middle driving gear (27) drives the middle transmission gear (28) to rotate, so that the middle transmission gear (28) drives the middle turntable (24) to rotate in the opposite direction, that is, the rotation direction of the middle turntable (24) is opposite to that of the upper turntable (23) and the lower turntable (25), thereby realizing the reverse rotation of adjacent turntables, thereby driving the upper baffle (8), the middle baffle (9) and the lower baffle (13) corresponding to the three groups of turntables to form a disturbance in the lower hopper (22) in a staggered direction, thereby promoting the dispersion, mixing and homogenization of high-viscosity fluids; The servo motor 1 (10) is started synchronously to drive the main screw (17) to rotate, and the high-viscosity fluid is continuously pushed into the sleeve (14) through the bottom outlet, and is steadily and evenly advanced by the main screw (17), thereby achieving quantitative extrusion of the high-viscosity mixture. The extruded mixed material is directly deposited on the building platform through the end nozzle, completing layer-by-layer deposition molding.

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