A concrete interlayer sewing weaving device for enhancing the interlayer bonding force of 3D printed concrete

Abstract

A kind of concrete interlayer sewing weaving device for enhancing the interlayer bonding force of 3D printing concrete, comprising a pitch adjusting track;A concrete 3D printer, a concrete sewing mechanism and a pre-punching mechanism are installed in order from front to back along the pitch adjusting track;Pitch adjusting stepper motor is arranged in the concrete 3D printer, the concrete sewing mechanism and the pre-punching mechanism, the power output end of each pitch adjusting stepper motor is engaged with the rack on the pitch adjusting track through the first gear, for driving the concrete 3D printer, the concrete sewing mechanism and the pre-punching mechanism to move on the track to adjust the distance between each other;Through this technology, the interfacial bonding force, crack resistance and durability of 3D printing concrete structure are significantly improved, and it can be widely used in building, infrastructure, seismic and high load structure field.

Description

Technical Field

[0001] This invention relates to the fields of building engineering and additive manufacturing technology, specifically to a concrete interlayer sewing and weaving device for enhancing the interlayer bonding strength of 3D printed concrete. Background Technology

[0002] 3D-printed concrete technology, as an innovative construction technique in the building industry, enables efficient and low-cost building manufacturing, reduces the use of formwork, and optimizes material utilization. However, because 3D-printed concrete is constructed using a layered stacking method, its interlayer bonding strength is weaker than that of traditional monolithic cast concrete, making it prone to interlayer delamination and cracking, thus limiting its application in high-load-bearing and high-durability structures. Currently, to improve interlayer bonding performance, researchers mainly focus on optimizing concrete material formulations, adjusting printing parameters (such as interlayer time intervals and nozzle pressure), or applying mechanical vibration during the printing process. However, while 3D-printed concrete offers high construction efficiency and design flexibility, the printing process, where each layer of concrete is not fully cured, results in insufficient adhesion between new and old layers, easily leading to interlayer delamination and weakened interfaces. Existing methods still struggle to completely eliminate weak interlayer bonding, especially under complex stress conditions; interlayer delamination remains one of the main causes of failure in 3D-printed concrete structures. The limitations in mechanical properties and durability urgently need to be addressed.

[0003] Patent application CN110774465A, entitled "An Interlayer Reinforcement Device and Method for 3D Printed Concrete," proposes a method to enhance the interlayer tensile and shear properties by pre-laying continuous fiber filaments (such as basalt fiber) on the surface of each concrete layer during the 3D printing process, before covering it with the next layer of concrete. The fiber bridging effect is utilized to improve the interlayer tensile and shear strength. In some embodiments, a robotic arm is used to assist in the fiber placement.

[0004] This application relies solely on interfacial bonding and lacks a physical anchoring mechanism; the fibers are merely laid flat on the interlayer surface and do not penetrate into the interior of the underlying cured concrete, thus failing to form a cross-layer mechanical interlocking or locking structure. Under high shear or impact loads, fiber pull-out or interfacial slippage is likely to occur.

[0005] It cannot adapt to complex stress paths; the fibers are laid out in a unidirectional or mesh-like manner, making it difficult to form a three-dimensional interwoven network. It has weak ability to suppress cracks in non-principal stress directions, resulting in limited overall improvement.

[0006] The construction efficiency is low and it is difficult to integrate synchronously; an additional fiber laying process is required, which is not completely synchronized with the printing process, increasing the complexity of the process. Furthermore, the fibers are easily disturbed and displaced by the subsequent concrete flow, affecting the consistency of the reinforcement effect. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, the present invention aims to provide a concrete interlayer sewing and weaving device to enhance the interlayer bonding strength of 3D printed concrete. By introducing interlayer sewing and weaving technology, the upper and lower concrete layers can form a stronger physical connection, significantly improving the interlayer bonding strength, enhancing the overall structural stability, and improving tensile, shear, and impact resistance. This achieves integrated performance enhancement of 3D printed concrete, improves the interlayer bonding strength of 3D printed concrete, and promotes the application of 3D printed concrete technology in a wider range of engineering fields.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A concrete interlayer sewing and weaving device for enhancing the interlayer bonding strength of 3D printed concrete includes: a spacing adjustment track 4; a concrete 3D printer 1, a concrete sewing mechanism 2, and a pre-drilling mechanism 3 installed sequentially from front to back along the spacing adjustment track 4; each of the concrete 3D printer 1, the concrete sewing mechanism 2, and the pre-drilling mechanism 3 is equipped with a spacing adjustment stepper motor 23, and the power output end of each spacing adjustment stepper motor 23 meshes with a rack 19 on the spacing adjustment track 4 through a first gear 24, for driving the concrete 3D printer 1, the concrete sewing mechanism 2, and the pre-drilling mechanism 3 to move on the track to adjust their spacing. The printing driver 28 of the concrete 3D printer 1, the sewing driver 11 of the concrete sewing mechanism 2, and the hole-opening driver 12 of the pre-hole-opening mechanism 3 are electrically connected to the main controller via wires to control the operation of the spacing adjustment motor.

[0009] The concrete 3D printer 1 includes commercial and laboratory models, including HC-3DPRT / L and HC-3DPRT / C.

[0010] The concrete sewing mechanism 2 includes a sewing driver 11 and a concrete sewing needle 26. The sewing driver 11 drives the spacing adjustment stepper motor 23 of the concrete sewing mechanism 2 to work, so that the first gear 24 in the concrete sewing mechanism 2 slides relative to the rack 19 of the spacing adjustment track 4. The concrete sewing needle 26 passes through the sewing driver 11. The sewing driver 11 is equipped with a Z-axis stepper motor 20. The Z-axis stepper motor 20 meshes with the Z-axis rack 18 located on the upper outer side of the concrete sewing needle 26 through the second gear 27, driving the concrete sewing needle 26 to move up and down.

[0011] The pre-drilling mechanism 3 includes a drilling driver 12 and a round-headed insert 22. The drilling driver 12 drives the spacing adjustment stepper motor 23 of the pre-drilling mechanism 3 to work, so that the first gear 24 in the pre-drilling mechanism 3 slides relative to the rack 19 of the spacing adjustment track 4. The round-headed insert 22 passes through the drilling driver 12. The drilling driver 12 is equipped with a Z-axis stepper motor 20. The Z-axis stepper motor 20 meshes with the rack 18 located on the upper outer side of the round-headed insert 22 through the second gear 27, driving the round-headed insert 22 to move up and down.

[0012] The concrete sewing needle 26 includes a hollow needle tube 15, inside which multiple V-shaped self-fixing pins 5 are stacked. A thread guide tube 17 is symmetrically fixed on both sides of the hollow needle tube 15. The concrete sewing thread 7 passes through the thread guide tube 17, with one end wound around a thread spool 6, which is mounted on the outer wall of the sewing driver 11. The front end of the hollow needle tube 15 has an arc-shaped notch 14. The concrete sewing thread 7 is guided through the thread guide tube 17 to the needle tip, then passes around the arc-shaped notch 14 and returns to the thread guide tube 17, forming a U-shaped path. A pin-feeding port 21 is located at the top of the hollow needle tube 15. A pin-feeding spring 25 is located inside the pin-feeding port 21 to push the V-shaped self-fixing pins 5 forward.

[0013] The V-shaped self-locking pin 5 is made of spring steel. In its natural state, it is in a V-shaped open state. Inside the hollow needle tube 15, it is in a U-shaped compressed state. After being pushed out, it automatically opens and can only move in one direction. The concrete sewing thread 7 is made of high-strength fiber or steel wire with a diameter of 1–3 mm and a tensile strength ≥500 MPa.

[0014] The round-headed insertion rod 22 is made of stainless steel, with a diameter of 4–7 mm and a rounded head.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Structural performance is significantly enhanced The interwoven stitching network provides a clear mechanical transfer path between layers, which can increase interlayer shear strength by 40%-60%, flexural strength by 20%-50%, and tensile strength by 50%-100%. At the same time, the unidirectional locking effect of the V-shaped self-fixing pins effectively prevents interlayer delamination, improving the crack resistance of the structure under complex loads such as earthquakes and impacts by more than 60%, thus solving the core defects of traditional 3D printed concrete that are prone to delamination and cracking.

[0016] 2. The overall structural integrity has been greatly improved. Interwoven sewing threads and V-shaped pins form an internal support structure similar to a steel mesh, transforming each layer of concrete from an independent load-bearing unit into a cohesive load-bearing whole. Under load, this structure can disperse localized concentrated stress over a wider area, avoiding structural failure caused by excessive local stress. This increases the overall load-bearing capacity of 3D-printed concrete structures by 35%-70%, meeting the requirements for high-load-bearing structures (such as bridge bearings and industrial plant columns).

[0017] 3. Improved controllability and efficiency in the printing process The printing-hole-sewing process is synchronized and linked by a controller according to a predetermined logic, avoiding the time wasted waiting for curing after printing in traditional processes, thus improving construction efficiency by 10%-30%. At the same time, the continuous sewing mechanism (pin release spring) and real-time parameter adjustment function ensure consistent sewing quality for each layer, reducing the scrap rate caused by human error.

[0018] 4. Wide range of material compatibility and engineering adaptability The concrete sewing thread uses high-strength fibers or steel wires, which can be adapted to different types of 3D printed concrete, such as ordinary concrete, high-performance concrete, and lightweight aggregate concrete, to meet the structural design requirements of different strength grades (C30-C80). In addition, this technology does not require changes to the core structure of the 3D printer. It can be modified simply by adding sewing and pre-drilling modules. It can be applied to conventional building components (walls, floors), complex irregular structures (curved shells, sculptures), and high-requirement projects (earthquake-resistant walls, bridge piers), thus expanding the application scenarios of 3D printed concrete.

[0019] In summary, this invention introduces sewing and weaving technology into the field of 3D printed concrete. By constructing a cross-layered interwoven stitching network, the bonding between upper and lower concrete layers is transformed from simple interfacial adhesion to a dual bonding mode of physical locking and interfacial adhesion, fundamentally solving the problem of weak interlayer bonding. By introducing sewing and weaving technology between concrete layers, stronger physical connections are formed, significantly improving interlayer bonding, enhancing overall structural stability, and increasing tensile, shear, and impact resistance. This achieves integrated performance enhancement of 3D printed concrete and improves its interlayer bonding. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a sewing and weaving device for concrete.

[0021] Figure 2 This is a three-dimensional schematic diagram of a concrete sewing mechanism.

[0022] Figure 3 This is a top view of a concrete sewing mechanism.

[0023] Figure 4This is a front view of a concrete sewing mechanism.

[0024] Figure 5 This is a cross-sectional view of a concrete sewing mechanism.

[0025] Figure 6 This is a top view of the structure of the sewing driver 11.

[0026] Figure 7 AA section view of sewing driver 11.

[0027] Figure 8 This is a BB cross-sectional view of the sewing driver 11.

[0028] Figure 9 This is a top view of the structure of the hole driver 12.

[0029] Figure 10 This is a cross-sectional view (AA) of the aperture actuator 12.

[0030] Figure 11 This is a BB cross-sectional view of the hole actuator 12.

[0031] Figure 12(a) is a simulation of a conventional 3D printed concrete beam.

[0032] Figure 12(b) is a simulation diagram of a 3D-printed concrete beam with sewing constraints.

[0033] In the diagram: 1. Concrete 3D printer; 2. Concrete sewing mechanism; 3. Pre-drilling mechanism; 4. Spacing adjustment track; 5. V-shaped self-locking pin; 6. Thread spool; 7. Concrete sewing thread; 8. Uncured printed concrete; 9. Cured concrete; 10. Sewing hole; 11. Sewing driver; 12. Drilling driver; 13. Released V-shaped self-locking pin; 14. Arc notch; 15. Hollow needle tube; 16. Closed V-shaped self-locking pin; 17. Thread guide tube; 18. Z-axis rack; 19. Rack; 20. Z-axis stepper motor; 21. Pin feed port; 22. Round-headed insertion rod; 23. Spacing adjustment stepper motor; 24. First gear; 25. Pin push spring; 26. Concrete sewing needle; 27. Second gear; 28. Printing driver. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the accompanying drawings.

[0035] See Figure 1A concrete interlayer sewing and weaving device for enhancing the interlayer bonding strength of 3D printed concrete includes a spacing adjustment track 4 and a main controller. A concrete 3D printer 1, a concrete sewing mechanism 2, and a pre-drilling mechanism 3 are sequentially mounted on the spacing adjustment track 4, all of which can slide left and right along the track. Each of the concrete 3D printer 1, concrete sewing mechanism 2, and pre-drilling mechanism 3 is equipped with a spacing adjustment stepper motor 23. The power output of each spacing adjustment stepper motor 23 meshes with a rack 19 on the spacing adjustment track 4 via a first gear 24 to drive the spacing adjustment between the mechanisms, thereby achieving orderly coordination of printing, drilling, and sewing operations.

[0036] The concrete 3D printer 1 includes commercial and laboratory models, including HC-3DPRT / L and HC-3DPRT / C.

[0037] See Figure 2 , Figure 5 The concrete sewing mechanism 2 includes a sewing driver 11 slidably connected to the spacing adjustment track 4. A hollow needle tube 15 is located below the sewing driver 11, and a needle delivery port 21 is located at the upper part of the hollow needle tube 15. (See also...) Figure 7 This is used to replenish the V-shaped self-locking pins 5. The hollow needle tube 15 is filled with stacked V-shaped self-locking pins 5. When the needle tube 15 is pulled out of the suture hole 10, the pin-pushing spring 25 automatically pushes the next V-shaped self-locking pin 5 to the suturing position under the action of elastic force, facilitating continuous suturing operations. The hollow needle tube 15 has symmetrically fixed thread guide tubes 17 on both sides. The concrete sewing thread 7 passes through the thread guide tubes 17, with one end wound around the thread reel 6, which is installed on the outer wall of the sewing driver 11. See also... Figure 3 The hollow needle tube 15 has an arc-shaped notch 14 at the front end. When the concrete sewing thread 7 is led to the needle position through the thread tube 17, it goes around the arc-shaped notch 14 and then goes back through the thread tube 17, thus forming a U-shaped path.

[0038] See Figure 7 The sewing driver 11 is penetrated by a concrete sewing needle 26 in the middle, and a Z-axis rack 18 is provided on the outer side of the upper part of the concrete sewing needle 26. The sewing driver 11 includes a Z-axis stepper motor 20, which meshes with the Z-axis rack 18 on the concrete sewing needle 26 through gears to drive the concrete sewing needle 26 to move up and down.

[0039] See Figure 1 , Figure 9 , Figure 10 , Figure 11The pre-drilling mechanism 3 includes a drilling driver 12 and a round-headed insertion rod 22. The upper part of the round-headed insertion rod 22 passes through the drilling driver 12, and a rack is provided on its outer side. A Z-axis stepper motor 22 is installed inside the drilling driver 12. The Z-axis stepper motor 22 meshes with the rack of the round-headed insertion rod 22 through gears, thereby driving the round-headed insertion rod 22 to move up and down. A spacing adjustment track 4 passes through the drilling driver 12. A spacing adjustment stepper motor 23 is installed inside the drilling driver 12. The spacing adjustment stepper motor 23 meshes with the rack on the spacing adjustment track 4 through gears, thereby driving the pre-drilling mechanism 3 to move left and right.

[0040] The main controller is electrically connected via wires to the printing driver of the concrete 3D printer 1, the sewing driver 11 of the concrete sewing mechanism 2, and the hole-opening driver 12 of the pre-drilling mechanism 3, controlling the operating parameters and linkage logic of the concrete 3D printer 1, the sewing driver 11, and the hole-opening driver 12. The control logic and parameters are set using conventional technical means and will not be described in detail here.

[0041] See Figure 5 The V-shaped self-fixing pin 5 is made of spring steel. In its natural state, it has a V-shaped opening structure. Inside the hollow needle tube 15, it is in a U-shaped compressed state. After being pushed out, it automatically opens and can only move in one direction.

[0042] The concrete sewing thread 7 is made of high-strength fiber or steel wire, with a diameter of 1-3mm and a tensile strength ≥500MPa.

[0043] The round-headed insertion rod 22 is made of stainless steel, with a diameter of 4-7mm and a rounded head.

[0044] The working principle of this invention is as follows: Under the control of the main controller, the device is started and the concrete 3D printer 1 prints a layer of uncured concrete and uses the pre-drilling mechanism 3 to pre-drill stitching holes 10. On the newly printed uncured concrete 8, the concrete sewing mechanism 2 is used by the concrete interlayer sewing weaving device to pass the concrete stitching thread 7 through the newly printed concrete and insert it into the pre-drilling hole 10 of the lower concrete. During the sewing process, the V-shaped self-fixing pin 5 enters the pre-drilling hole 10 of the lower concrete and is automatically fixed. The concrete stitching thread 7 passes around the V-shaped self-fixing pin 5 and returns to the other side of the uncured concrete 8, forming an interwoven sewing network. The pre-drilling mechanism 3 squeezes the upper concrete, causing some of the uncured concrete 8 to flow into the lower sewing hole 10, improving the interlayer density. The main controller adjusts the positioning of the concrete sewing mechanism 2, the arrangement of the concrete stitching thread 7, and the operation of the pre-drilling mechanism 3 in real time to ensure the sewing accuracy and interlayer bonding strength.

[0045] Implementation Examples I. Device Assembly and Parameter Setting Component selection and assembly Concrete 3D Printer 1: Screw extrusion printer (nozzle diameter 20mm); Concrete sewing mechanism 2: needle tube inner diameter 6mm, outer diameter 10mm, V-shaped self-fixing needle material is 65Mn spring steel (opening angle 60°, diameter 5mm), thread tube inner diameter 4mm, arc concave thread fixer concave surface radius 1.5mm; Pre-drilled hole mechanism 3: The diameter of the round-headed insertion rod is 6.5mm, and the material is 304 stainless steel; Concrete sewing thread 7: Aramid fiber thread (2mm diameter, tensile strength 800MPa) is selected. Main controller: A PLC controller (model S7-200SMART) is selected to connect the stepper motors of each driver.

[0046] Parameter settings: Printing parameters: layer height 20mm, printing speed 30mm / s; Spacing parameters: 50mm between the 3D printer and the sewing needle; 50mm between the concrete sewing mechanism 2 and the pre-drilling mechanism 3. Sewing parameters: Concrete sewing mechanism 2, Y-axis step distance 30mm, lifting speed 0.5m / s; Hole parameters: 22mm round head insert, 20mm hole depth, 1kN downward pressure.

[0047] II. Simulation Experiment Verification and Results The flexural mechanical properties of ordinary 3D-printed concrete beams and stitch-constrained concrete beams were verified using simulation software. C50 concrete was used as the material, and the interlayer bond performance of the 3D-printed concrete was simulated using the strength reduction method. Simulation results show that under the same loading conditions, there are significant differences in the flexural properties of ordinary 3D-printed concrete beams (Figure 12(a)) and stitch-constrained 3D-printed concrete beams (Figure 12(b)): In terms of load-bearing capacity: as the mid-span load gradually increases, the load-displacement curve of the ordinary 3D-printed concrete beam drops rapidly after the yield point, indicating a lower ultimate load-bearing capacity; while the load-displacement curve of the stitch-constrained beam has a higher peak value, with an ultimate load-bearing capacity increased by approximately 28%. In terms of stiffness retention: the stiffness of the ordinary beam decreases significantly after yielding, while the stitch-constrained beam maintains a certain load-bearing stiffness after yielding, exhibiting better stress stability. In terms of plastic deformation capacity: the maximum plastic strain of the stitch-constrained beam is about 35% higher than that of the ordinary beam, indicating a significant enhancement in its ductility and energy dissipation capacity. In terms of overall structural performance: the sewing constraint effectively improves the interlayer bonding effect, making the 3D printed concrete beam closer to the integral cast concrete beam in terms of macroscopic mechanical properties, exhibiting better integrity and safety.

[0048] The above simulations verified the effectiveness of the present invention. The sewing constraint technology can significantly improve the flexural bearing capacity, plastic deformation capacity and overall structural performance of 3D printed concrete beams, providing technical support for improving the reliability of engineering applications of 3D printed concrete components.

Claims

1. A concrete interlayer sewing and weaving device for enhancing the interlayer bonding strength of 3D printed concrete, characterized in that, include: Spacing adjustment track (4); a concrete 3D printer (1), a concrete sewing mechanism (2) and a pre-drilling mechanism (3) are installed sequentially from front to back along the spacing adjustment track (4); the concrete 3D printer (1), the concrete sewing mechanism (2) and the pre-drilling mechanism (3) are all equipped with a spacing adjustment stepper motor (23), and the power output end of each spacing adjustment stepper motor (23) is engaged with the rack (19) on the spacing adjustment track (4) through the first gear (24) to drive the concrete 3D printer (1), the concrete sewing mechanism (2) and the pre-drilling mechanism (3) to move on the track to adjust the spacing between them; The printing driver (28) of the concrete 3D printer (1), the sewing driver (11) of the concrete sewing mechanism (2) and the hole-opening driver (12) of the pre-hole-opening mechanism (3) are electrically connected to the main controller via wires to control the operation of the spacing adjustment motor.

2. The apparatus according to claim 1, characterized in that, The concrete sewing mechanism (2) includes a sewing driver (11) and a concrete sewing needle (26). The sewing driver (11) drives the spacing adjustment stepper motor (23) of the concrete sewing mechanism (2) to work, so that the first gear 24 in the concrete sewing mechanism (2) slides relative to the rack 19 of the spacing adjustment track (4). The concrete sewing needle (26) passes through the sewing driver (11). The sewing driver (11) is equipped with a Z-axis stepper motor (20). The Z-axis stepper motor (20) meshes with the Z-axis rack (18) located on the upper outer side of the concrete sewing needle (26) through the second gear 27, driving the concrete sewing needle (26) to move up and down.

3. The apparatus according to claim 1, characterized in that, The pre-drilling mechanism (3) includes a drilling driver (12) and a round-headed insert (22). The drilling driver (12) drives the spacing adjustment stepper motor (23) of the pre-drilling mechanism (3) to work, so that the first gear 24 in the pre-drilling mechanism (3) slides relative to the rack 19 of the spacing adjustment track (4). The round-headed insert (22) passes through the drilling driver (12). The drilling driver (12) is equipped with a Z-axis stepper motor (20). The Z-axis stepper motor (20) meshes with the rack (18) located on the upper outer side of the round-headed insert (22) through the second gear 27, driving the round-headed insert (22) to move up and down.

4. The apparatus according to claim 2, characterized in that, The concrete sewing needle (26) includes a hollow needle tube (15), inside which are stacked multiple V-shaped self-fixing pins (5); the hollow needle tube (15) is symmetrically fixed with thread tubes (17) on both sides, and the concrete sewing thread (7) passes through the thread tube (17), with one end wound on the thread spool (6), which is installed on the outer wall of the sewing driver (11); the front end of the hollow needle tube (15) is provided with an arc notch (14), and the concrete sewing thread (7) is led to the needle head position through the thread tube (17), then passes around the arc notch (14) and passes back through the thread tube (17), forming a U-shaped path; the upper part of the hollow needle tube (15) is provided with a pin feeding port (21), and a pin pushing spring (25) is provided in the pin feeding port (21) to push the V-shaped self-fixing pins (5) forward.

5. The apparatus according to claim 4, characterized in that, The V-shaped self-fixing pin (5) is made of spring steel. In its natural state, it is in a V-shaped open state. In the hollow needle tube (15), it is in a U-shaped compressed state. After being pushed out, it automatically opens and can only move in one direction.

6. The apparatus according to claim 3, characterized in that, The round-headed insert (22) is made of stainless steel, with a diameter of 4–7 mm and a rounded head.

7. The apparatus according to claim 4, characterized in that, The concrete sewing thread (7) is made of high-strength fiber or steel wire with a diameter of 1–3 mm and a tensile strength of ≥500 MPa.

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