Magnetic field controlled 3D printing concrete constructability enhancement device and method

Abstract

The application relates to a magnetic field controlled 3D printing concrete constructability improving device and method, wherein the 3D printing device comprises a printing unit, a magnetic field unit and a control unit; the printing unit comprises a printing platform and a printing device body arranged above the printing platform; the magnetic field unit is used for applying a magnetic force to concrete on the printing platform; and the control unit comprises a printing control element connected with the printing unit and used for controlling the printing device body to extrude the concrete, and a magnetic field control element connected with the magnetic field unit; during printing, the control unit controls the magnetic force size according to the printing height and the concrete hardening state, so that the concrete does not deform. Compared with the prior art, the application can solve the problem that 3D printing concrete is prone to overturning and collapse, the method can obtain higher concrete constructable layers and a stable printing construction process, the 3D printing concrete constructability is improved, the printing operation is convenient, the concrete performance is excellent, and an automatic additive manufacturing process is realized.

Description

Technical Field

[0001] This invention belongs to the fields of additive manufacturing technology and electromagnetic control technology, and in particular relates to a magnetic field-controlled 3D printed concrete constructability enhancement device and method. Background Technology

[0002] 3D printed concrete technology has gradually become a new construction technology with high design freedom, high automation, low labor costs, and low environmental pollution. However, with the increasing attention and interest in this field in recent years, the key technical challenges and bottlenecks of 3D printed concrete technology have also become increasingly apparent. Achieving high constructability of 3D printed concrete under current concrete technology is not easy. This is because the required slurry properties during the pumping and extrusion stage of 3D printing are significantly different from those required in the post-extrusion construction stage. This necessitates that engineers overcome the contradiction between low viscosity and high yield stress in concrete rheology.

[0003] The development of electromagnetic physics offers a feasible solution to 3D printed concrete technology. By directly adding magnetic responsive materials to concrete or spraying them during the 3D printing process, and applying a stable, uniform magnetic field externally, the concrete material can be uniformly stressed within the magnetic field, thus addressing the problem of poor constructability in 3D printing. Furthermore, since no mechanical contact is required between the object and the electromagnetic device in the magnetic field, the non-mechanical contact provided by electromagnetic force does not cause noise or friction problems. The energy used is renewable electrical energy, offering advantages such as being green, environmentally friendly, safe, and reliable.

[0004] Chinese patent CN 113555183 B discloses a method for generating a uniform magnetic field, a magnetic field coil, a device, equipment, and a storage medium. This method uses a magnetic field coil group with two saddle-shaped coils symmetrically arranged radially along the cylindrical surface, improving the uniformity of the magnetic field. Meanwhile, Chinese patent CN 116872493 A discloses a strong magnetic field anti-gravity levitation bio-additive manufacturing device and method, providing a solution for seamless printing of complete three-dimensional biological structures in the field of magnetic field-based bio-additive manufacturing. Chinese patent CN 108621420 B discloses a magnetically assisted 3D printing device and method, which achieves unsupported 3D printing of polymer-based magnetic metal composite materials and prevents edge warping. Chinese patent CN 109605733 B discloses a magnetic material 3D printing equipment, which has a magnetization device at the lower end of the screw extrusion structure, improving the molding efficiency and magnetic properties of magnetic materials. However, the above patents do not involve solutions for intelligently adjusting the magnetic field strength based on the time-varying effect of the printed structure, nor are they applicable to 3D printed concrete structures, and cannot meet the requirements for the use of 3D printing in the field of civil engineering. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art by providing a magnetic field-controlled 3D printed concrete constructability enhancement device and method.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] The first aspect of this invention provides a magnetic field-controlled 3D printing concrete apparatus for printing concrete, the 3D printing apparatus comprising:

[0008] A printing unit includes a printing platform and a printing device body disposed above the printing platform;

[0009] A magnetic field unit for applying magnetic force to the concrete on the printing platform; and

[0010] The control unit includes a printing control component connected to the printing unit and used to control the extrusion of concrete by the printing device body, and a magnetic field control component connected to the magnetic field unit.

[0011] As the height of the concrete gradually increases, the magnetic field unit applies a magnetic force to the concrete to prevent it from overturning.

[0012] Furthermore, the magnetic field unit includes:

[0013] Roller electrode plates with adjustable height are located on both sides of the printing platform;

[0014] An identification element is provided on the upper end of the roller shutter electrode plate;

[0015] And a plurality of miniature magnetic field generating arrays disposed on the side of the roller shutter electrode plate facing the printing platform;

[0016] The identification device identifies the hardening state and deformation of the concrete and sends a signal to the magnetic field control device, which applies a magnetic force to the concrete to prevent it from overturning.

[0017] Furthermore, the height of the roller shutter electrode plate is controlled by the printing control unit to ensure that the roller shutter electrode plate is at the same height as the concrete extruded by the printing unit.

[0018] Furthermore, the micro magnetic field generating array is uniformly distributed along the height direction of the roller shutter electrode plate.

[0019] Furthermore, the identification element includes:

[0020] The movable guide rail is located at the upper end of the roller shutter electrode plate, and the movable guide rail is provided with several low-friction bearings inside.

[0021] A stabilizer located on the upper surface of the moving guide rail;

[0022] A rectangular mounting cavity located on the upper surface of the stabilizer;

[0023] A horizontal calibrator is installed inside the mounting cavity;

[0024] A laser positioning device is installed inside the mounting cavity;

[0025] A thermal imager installed inside the mounting cavity;

[0026] A high-precision camera located inside the mounting cavity and next to the thermal imager;

[0027] And a lens protection plate covering the outer surface of the thermal imager and the high-precision camera.

[0028] Furthermore, the printing unit includes:

[0029] A slurry feeding device connected to an external slurry feeding device and located on top of the printing device body includes several slurry feeding hoses connected to the external slurry feeding device and a speed controller located between the several slurry feeding hoses.

[0030] A spiral blade extrusion controller connected to the slurry feeder;

[0031] A stress sensor is located between the spiral blade extrusion controller and the slurry feeder, and is positioned at the front end of the speed controller and abuts against the spiral blade extrusion controller.

[0032] The printing nozzle is connected to the spiral blade extrusion controller;

[0033] The printing unit also includes a magnetic material feeder connected to the printing nozzle and to an external magnetic material feeding device, wherein the printing nozzle sprays magnetic material onto the concrete to satisfy the magnetic field unit applying magnetic force to the concrete.

[0034] Furthermore, the helical blade extrusion controller includes:

[0035] The transmission rod connected to the speed controller;

[0036] And helical blades that spiral around the outer surface of the transmission rod;

[0037] As the slurry is driven to the printing nozzle by the spiral blades, the stress sensor transmits the rheological parameters of the slurry and sends a signal to the printing controller to enable the printing controller to control the rotation speed of the speed controller.

[0038] This invention also provides a magnetic field-controlled method for improving the constructability of 3D-printed concrete, which is executed by the aforementioned magnetic field-controlled 3D-printed concrete constructability improvement device. The method includes the following steps:

[0039] S1: Obtain the concrete printing structure and input it into the printing control component;

[0040] S2: The slurry feeding device and the magnetic material feeding device feed the printing unit. The slurry feeding device sends a signal to the printing control device. The printing control device controls the speed controller to start printing. The stress sensor transmits the rheological parameters of the slurry and sends a signal to the printing control device. When the slurry is extruded to the printing platform, the printing nozzle sprays magnetic material onto the outer surface of the concrete.

[0041] S3: Concrete accumulates layer by layer on the printing platform, and the roller shutter electrode plate rises accordingly. The identification device identifies the concrete information and sends a signal to the magnetic field control device. The magnetic field control device controls the magnetic field strength generated by the micro magnetic field generating array to prevent the concrete from overturning.

[0042] S4: Printing complete. Curing of the concrete.

[0043] Further, in step S3, the magnetic field control component controls the micro magnetic field generating array to gradually increase the magnetic field strength generated by the printed concrete as the 3D printed concrete hardens, so as to ensure that the printed concrete does not undergo horizontal deformation. The magnetic force provided by the magnetic field strength satisfies the following formula:

[0044] ；

[0045] in, ξ k It refers to the hardening rate of 3D printed concrete. t It refers to the hardening time of 3D-printed concrete. μ 0 is the permeability in a vacuum. n It is the number of turns of the coil. I It depends on the magnitude of the coil current. b i It is the unit vector of the i-th micro magnetic field generator. r It is the distance from the magnetic field source. V Let be the volume of the magnetic material in the 3D-printed concrete, and ▽(MB) be the dot product of the magnetic moment and the gradient of the magnetic field at that point. μ s It is the static friction coefficient between 3D printed concrete and the printed working surface. F s It is the static friction between the 3D printed concrete and the printing platform. δIt refers to the horizontal deformation of 3D printed concrete.

[0046] Furthermore, the magnetic field strength generated by the micro-magnetic field generating array controlled by the magnetic field control component provides a torque balance to the lateral overturning force distributed along the printing height of the 3D printed concrete, and the relationship between the magnetic force provided by the magnetic field strength and the printing height satisfies the following formula:

[0047] ；

[0048] ;

[0049] ;

[0050] in, ξ k It refers to the hardening rate of 3D printed concrete. v It's printing speed. h It refers to the printing height of 3D printed concrete. l It is the length of a single-layer printing strip along the printing direction. μ 0 is the permeability in a vacuum. n It is the number of turns of the coil. I It depends on the magnitude of the coil current. b i It is the unit vector of the i-th micro magnetic field generator. r It is the distance from the magnetic field source. V Let be the volume of the magnetic material in the 3D-printed concrete, and ▽(MB) be the dot product of the magnetic moment and the gradient of the magnetic field at that point. μ s It is the static friction coefficient between 3D printed concrete and the printed working surface. F s It is the static friction between the 3D printed concrete and the printing surface. δ This refers to the horizontal deformation of the 3D-printed concrete, where ρ is the average density of the slurry. g It is the acceleration due to gravity. h For printing height, K This is the lateral overturning force reduction factor.

[0051] Specifically, the magnetic force analysis of concrete during the printing process is as follows:

[0052] A miniature magnetic field generating array, where the magnetic field strength of the miniature magnetic field generator is controlled by the current intensity of the energized solenoid, thereby forming a uniform magnetic field that can be intelligently adjusted according to the hardening state of the printed sample. Based on the nonlinear hardening process of the printed sample, its stiffness undergoes a time-varying evolution function. K ( t This can be represented as:

[0053] ;

[0054] in, ξ k It is the hardening rate. t It is the hardening time. K 0 represents the initial stiffness.

[0055] Regarding the magnetic field strength of the aforementioned micro-magnetic field generator, if a Cartesian coordinate system is established with the plane where the micro-magnetic field generator is located, then the magnetic field strength generated by a single micro-magnetic field generator is... B 0 can be represented as:

[0056] ;

[0057] in, μ 0 It is the magnetic permeability in a vacuum. n It is the number of turns of the coil. I It is determined by the magnitude of the coil current.

[0058] For the aforementioned micro-magnetic field generating array, the contribution of the magnetic field source array formed by the individual micro-magnetic field generators to the total magnetic field needs to be considered. Since the direction and intensity of each magnetic field source are known, the total magnetic field intensity is determined by the principle of vector addition. B s It can be represented as:

[0059] ;

[0060] Among them, B i b is the magnetic field strength of the i-th micro magnetic field generator. i It is the unit vector of the i-th micro magnetic field generator.

[0061] Concrete is subjected to magnetic force in a uniform magnetic field generated by a miniature magnetic field generator. Assume the distance between the concrete and the magnetic field generator is... r Then the magnetic field strength at that location B r With distance r The change can be represented as:

[0062] ;

[0063] in, r It is the distance from the magnetic field source.

[0064] Magnetic force on concrete at this location F m It can be represented as:

[0065] ;

[0066] in, B r It is the magnetic field strength at the location of the 3D-printed concrete. V is the volume of the magnetic material in the 3D printed sample, and ▽(MB) is the dot product of the magnetic moment and the magnetic field gradient at that point.

[0067] The forces acting on the concrete in the magnetic field should conform to Newton's second law. Therefore, the equilibrium equation satisfying Newton's second law can be expressed as:

[0068] ;

[0069] in, F m It refers to the magnetic force exerted on 3D-printed concrete at a certain location. μ s It is the static friction coefficient between 3D printed concrete and the printed working surface. F s It is the static friction between the 3D printed concrete and the printing surface. m It is the total mass of the 3D-printed concrete. a It is the acceleration of motion.

[0070] In summary, based on the aforementioned time-varying stiffness evolution function K ( t and total magnetic field strength B s It can be seen that the control system of the magnetic field generator should control the total magnetic field strength in accordance with the time-varying hardening characteristics of the printed sample. According to the equilibrium equation, the total magnetic field strength should be determined by the current passing through the coil of each miniature magnetic field generator. I Number of coil turns n The distance between the printed sample and the magnetic field source r Then, using Maxwell's equations and the Bingham fluid model, the magnetic control equations for the printed sample can be obtained. F ( I ):

[0071] ;

[0072] in, ξ k It is the hardening rate. t It is the hardening time. μ 0 is the permeability in a vacuum. n It is the number of turns of the coil. I It depends on the magnitude of the coil current. b i It is the unit vector of the i-th micro magnetic field generator. r It is the distance from the magnetic field source.V denoted as , where ▽(MB) is the volume of the magnetic material in the 3D-printed sample, and ∠(MB) is the dot product of the magnetic moment and the gradient of the magnetic field at that point. μ s It is the static friction coefficient between 3D printed concrete and the printed working surface. F s It is the static friction between the 3D printed concrete and the printing surface. δ It refers to the horizontal deformation of the printed sample.

[0073] As 3D-printed concrete accumulates layer by layer, the upper layers exert vertical pressure on the lower layers, causing the lower layers to deform horizontally. This horizontal deformation accumulates from bottom to top, eventually exceeding the lateral deformation and overturning limit of the 3D-printed concrete, leading to the collapse of the printed sample. Therefore, the aforementioned magnetic control equations... F ( I This technology can effectively prevent deformation of the underlying printing strips while applying controllable magnetic force to enhance the constructability of 3D printed concrete structures. The printing height is determined by the printing speed and strip length. h This can be expressed by a functional relationship as follows:

[0074] ;

[0075] in, t n It is the time it takes for the printing equipment to run up to time n. t 0 represents the time when the printing equipment begins to extrude concrete onto the printing platform. v It's printing speed. l It is the length of a single-layer printing strip along the printing direction.

[0076] Then the magnetic control equation F ( I It can be deformed to match the printing height. h Related functions F ( h ):

[0077] ；

[0078] Based on the relationship between lateral pressure and vertical compressive stress in the template according to Janssen's theory, the lateral overturning force of 3D-printed concrete is derived by analogy. P ( h The functional relationship between the print height and the print height is as follows:

[0079] ;

[0080] in, ρTo determine the average density of the printing paste, g It is the acceleration due to gravity. h For printing height, K This is the lateral overturning force reduction factor.

[0081] By the principle of torque balance, we can obtain:

[0082] ;

[0083] Based on the balance between the magnetic force and the lateral overturning force, the control unit can perform real-time calculations and feedback to provide a stable and controllable external magnetic field, preventing the 3D printed concrete from undergoing horizontal deformation and overturning.

[0084] Compared with the prior art, the present invention has the following beneficial effects:

[0085] (1) Existing 3D printed concrete relies mainly on the rheological properties of the material itself to balance constructability and extrudability. However, the load-bearing capacity of 3D printed concrete in its freshly mixed state is limited, making it difficult to achieve higher layers in 3D printing. The device of this invention is based on 3D printing technology and utilizes the force characteristics of magnetic materials in a magnetic field to improve the constructability of 3D printed concrete. During its construction process, it realizes the coordinated operation of digital image monitoring, artificial intelligence technology optimization control, and intelligent feedback adjustment mechanism, which greatly improves the automation level of 3D printed concrete, and produces a high number of concrete layers with excellent mechanical properties.

[0086] (2) This invention is of great significance and practical value for improving the design freedom of 3D printed concrete, using computer technology for refined and automated control, improving the timeliness and accuracy of monitoring, and reducing the safety risks of 3D printed concrete structures during the construction process. Attached Figure Description

[0087] Figure 1 This is a schematic diagram of the overall structure of the device in Example 1.

[0088] Figure 2 This is a schematic diagram of the forces acting on concrete in a magnetic field in Example 2.

[0089] Figure 3 This is a schematic diagram of the stress analysis of a single-layer strip of concrete during the 3D printing process in Example 2.

[0090] Figure 4 This is a schematic diagram of the magnetic induction lines of a single micro magnetic field generator in a planar Cartesian coordinate system in Examples 1 and 2.

[0091] Figure 5 This is a schematic diagram showing the distribution of lateral overturning force along the printing height in 3D printed concrete in Examples 1 and 2.

[0092] Figure 6 This is a schematic diagram of the micro magnetic field generating array in Examples 1 and 2.

[0093] Figure 7 This is a cross-sectional view of the identification component in Example 1.

[0094] Figure 8 This is a cross-sectional view of the printing unit in Example 1.

[0095] Figure 9 This is a schematic diagram illustrating the specific steps of the printing method in Example 2.

[0096] Numbering on the map:

[0097] 1-Printing unit, 101-Printing platform, 102-Printing equipment body, 103-Slurry feeder, 104-Spiral blade extrusion controller, 105-Stress sensor, 106-Printing nozzle, 107-Magnetic material feeder, 108-Feeding hose, 109-Speed ​​controller, 110-Drive rod, 111-Spiral blade, 2-Magnetic field unit, 201-Roller electrode plate, 202-Identifier, 203-Miniature magnetic field generating array, 204-Moving guide rail, 205-Low friction bearing, 206-Stabilizer, 207-Mounting cavity, 208-Level calibrator, 209-Laser positioning device, 210-Thermal imager, 211-High-precision camera, 212-Lens protection plate, 3-Control unit, 301-Printing control component, 302-Magnetic field control component. Detailed Implementation

[0098] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0099] Unless otherwise specified in this technical solution, the component model, material name, connection structure, control method, and other features are considered to be common technical features disclosed in the prior art.

[0100] In the description of this invention, it should be understood that the terms "upper", "lower", "vertical", "horizontal", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0101] In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integrated connection; they can refer to a bolted connection or a welded connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0102] To achieve a higher number of concrete layers without deformation and with excellent mechanical properties, the first aspect of this invention provides a magnetically controlled 3D-printed concrete constructability lifting device, the structure of which can be found in [reference needed]. Figures 1-7 As shown, it includes:

[0103] The printing unit 1 includes a printing platform 101 and a printing device body 102 disposed above the printing platform 101;

[0104] Magnetic field unit 2, which is used to apply magnetic force to the concrete on the printing platform 101; and

[0105] The control unit 3 includes a printing control component 301 connected to the printing unit 1 and used to control the extrusion of concrete by the printing device body 102, and a magnetic field control component 302 connected to the magnetic field unit 2.

[0106] As the height of the concrete gradually increases, the magnetic field unit 2 applies a magnetic force to the concrete to prevent it from overturning.

[0107] For some specific implementation methods, please refer to [link / reference]. Figures 1 to 7 As shown, the magnetic field unit 2 includes:

[0108] Roller electrode plates 201, which are height-adjustable and located on both sides of the printing platform 101;

[0109] An identification element 202 is disposed on the upper end of the roller shutter electrode plate 201;

[0110] And a plurality of miniature magnetic field generating arrays 203 disposed on the side of the roller shutter electrode plate 201 facing the printing platform 101;

[0111] The identification element 202 identifies the hardening state and deformation of the concrete and sends a signal to the magnetic field control element 302, which applies a magnetic force to the concrete to prevent it from overturning.

[0112] In this embodiment, the roller shutter electrode plate 201 has electric shock protection, and a hot-swappable circuit board is provided at one end of the roller shutter electrode plate 201 facing the printing unit 1. The hot-swappable circuit board is used to install the micro magnetic field generating array 203. The roller shutter electrode plate 201 rises with the increase of the number of concrete layers, so that the magnetic field strength can be received by concrete of different layer heights. It should be noted that in this embodiment, the roller shutter electrode plate 201 is preferred. Of course, those skilled in the art should understand that the roller shutter electrode plate 201 is only a preferred embodiment of one aspect of the magnetic field unit 2. Other existing or future components with similar functions to the roller shutter electrode plate 201 that are applicable to this application should also be included within the scope of protection of this application, and are hereby incorporated by reference.

[0113] In this embodiment, the micro magnetic field generating array 203 is composed of multiple micro magnetic field generators arranged in a row. Each micro magnetic field generator has a diameter of 1-3 mm and is made of nano-copper wire coated with an insulating coating wound around the surface of a cylinder. It is installed on a hot-swappable circuit board on the inner surface of the flexible roller shutter electrode plate according to the array arrangement position, facing the direction of the printing unit 1. The micro magnetic field generating array is connected to the hot-swappable circuit board. It should be noted that in this embodiment, the micro magnetic field generating array 203 is preferred. Of course, those skilled in the art should understand that the micro magnetic field generating array 203 is only a preferred embodiment of one aspect of the magnetic field unit 2. Other existing or future components with similar functions to the micro magnetic field generating array 203 that are applicable to this application should also be included within the scope of protection of this application, and are hereby incorporated by reference.

[0114] In this embodiment, the identification component 202 can monitor the strip hardening, strip appearance, structural deformation, structural thermal field distribution, and structural cracking defects during the concrete printing process in real time. It can also identify and process the above images to obtain the time-varying hardening state of the strip in different printing layers, and generate a photograph of the actual object and a grayscale image after binarization. After the grayscale image is converted, it is fed back to the magnetic field control component 302 to adjust the magnetic field strength at different printing layer positions so that the strip is balanced in the horizontal direction in the magnetic field and does not cause volume deformation of the strip in the horizontal direction.

[0115] For more detailed implementation methods, please refer to [link / reference]. Figure 1 As shown, the height of the roller shutter electrode plate 201 is controlled by the printing control component 301 to ensure that the roller shutter electrode plate 201 is at the same height as the concrete extruded by the printing unit 1.

[0116] For more detailed implementation methods, please refer to [link / reference]. Figure 1 As shown, the micro magnetic field generating array 203 is uniformly distributed along the height direction of the roller shutter electrode plate 201.

[0117] For more detailed implementation methods, please refer to [link / reference]. Figure 7 As shown, the identification element 202 includes:

[0118] The movable guide rail 204 is located at the upper end of the roller shutter electrode plate 201, and the movable guide rail 204 is provided with several low-friction bearings 205 inside;

[0119] Stabilizer 206 located on the upper surface of the moving guide rail 204;

[0120] A rectangular mounting cavity 207 is located on the upper surface of the stabilizer 206;

[0121] A leveling instrument 208 is installed inside the mounting cavity 207;

[0122] A laser positioning device 209 is installed inside the mounting cavity 207;

[0123] Thermal imager 210 is installed inside the mounting cavity 207;

[0124] A high-precision camera 211 is located inside the mounting cavity 207 and next to the thermal imager 210;

[0125] And a lens protection plate 212 covering the outer surface of the thermal imager 210 and the high-precision camera 211.

[0126] In this embodiment, the horizontal calibrator 208, laser positioning device 209, thermal imager 210, and high-precision camera 211 can monitor the strip hardening, strip appearance, structural deformation, structural thermal field distribution, and structural cracking defects during the concrete printing process in real time. They also identify and process the images to obtain the time-varying hardening state of the strip in different printing layers, generating both physical photographs and binarized grayscale images. After conversion processing, the grayscale images are fed back to the magnetic field control device 302 to adjust the magnetic field strength at different printing layer positions, ensuring that the strip is horizontally balanced in the magnetic field without causing volumetric deformation in the horizontal direction. It should be noted that, in this embodiment, the preferred components are a leveling device 208, a laser positioning device 209, a thermal imager 210, and a high-precision camera 211. Of course, those skilled in the art should understand that the leveling device 208, laser positioning device 209, thermal imager 210, and high-precision camera 211 are only preferred embodiments of one aspect of the identification device 202. Other existing or future components with similar functions to the leveling device 208, laser positioning device 209, thermal imager 210, and high-precision camera 211, if applicable to this application, should also be included within the scope of protection of this application, and are hereby incorporated by reference.

[0127] For some specific implementation methods, please refer to [link / reference]. Figure 1 and Figure 8 As shown, the printing unit 1 includes:

[0128] The slurry feeding component 103, which is connected to an external slurry feeding device and located on top of the printing device body 102, includes a plurality of feeding hoses 108 connected to the external slurry feeding device and a speed controller 109 located between the plurality of feeding hoses 108.

[0129] The spiral blade extrusion controller 104 is connected to the slurry feeder 103;

[0130] The stress sensor 105, located between the spiral blade extrusion controller 104 and the slurry feeder 103, is disposed at the front end of the speed controller 109 and abuts against the spiral blade extrusion controller 104.

[0131] The printing nozzle 106 is connected to the spiral blade extrusion controller 104;

[0132] The printing unit also includes a magnetic material feeder 107 connected to the printing nozzle 106 and to an external magnetic material feeding device. The printing nozzle 106 sprays magnetic material onto the concrete to satisfy the magnetic field unit 2 applying magnetic force to the concrete.

[0133] For more detailed implementation methods, please refer to [link / reference]. Figure 1 and Figure 8 As shown, the spiral blade extrusion controller 104 includes:

[0134] The transmission rod 110 is connected to the speed controller 109;

[0135] And helical blades 111 spirally surrounding the outer surface of the transmission rod 110;

[0136] As the slurry is driven to the printing nozzle 106 by the spiral blade 111, the stress sensor 105 transmits the rheological parameters of the slurry and sends a signal to the printing control unit 301 to control the rotation speed of the speed controller 109.

[0137] This invention also provides a magnetic field-controlled method for improving the constructability of 3D-printed concrete, which is executed by the aforementioned magnetic field-controlled 3D-printed concrete constructability improvement device. The steps are detailed in [link to documentation]. Figure 9 As shown, the method includes the following steps:

[0138] S1: Obtain the concrete printing structure and input it into the printing control unit 301;

[0139] S2: The slurry feeding device and the magnetic material feeding device feed the printing unit 1. The slurry feeding device 103 sends a signal to the printing control device 301. The printing control device 301 controls the speed controller 109 to start printing. The stress sensor 105 transmits the rheological parameters of the slurry and sends a signal to the printing control device 301. When the slurry is extruded to the printing platform 101, the printing nozzle 106 sprays magnetic material onto the outer surface of the concrete.

[0140] S3: Concrete accumulates layer by layer on the printing platform 101. As the roller shutter electrode plate 201 rises, the identification component 202 identifies the concrete information and sends a signal to the magnetic field control component 302. The magnetic field control component 302 controls the magnetic field strength generated by the micro magnetic field generating array 203 to prevent the concrete from overturning.

[0141] S4: Printing complete. Curing of the concrete.

[0142] For some specific implementation methods, please refer to [link / reference]. Figure 9 As shown, in step S3, the magnetic field control unit (302) controls the micro magnetic field generating array (203) to gradually increase the magnetic field strength generated by the printed concrete as the 3D printed concrete hardens, so that the printed concrete does not undergo horizontal deformation. The magnetic force provided by the magnetic field strength satisfies the following formula:

[0143] ；

[0144] in, ξ k It refers to the hardening rate of 3D printed concrete. t It refers to the hardening time of 3D-printed concrete. μ 0 is the permeability in a vacuum. n It is the number of turns of the coil. I It depends on the magnitude of the coil current. b i It is the unit vector of the i-th micro magnetic field generator. r It is the distance from the magnetic field source. V Let be the volume of the magnetic material in the 3D-printed concrete, and ▽(MB) be the dot product of the magnetic moment and the gradient of the magnetic field at that point. μ s It is the static friction coefficient between 3D printed concrete and the printed working surface. F s It is the static friction between the 3D printed concrete and the printing platform. δ It refers to the horizontal deformation of 3D printed concrete.

[0145] For some specific implementation methods, please refer to [link / reference]. Figure 9As shown, the magnetic field strength generated by the micro magnetic field generating array 203 controlled by the magnetic field control component 302 provides a torque balance to the lateral overturning force distributed along the printing height of the 3D printed concrete. The relationship between the magnetic force provided by the magnetic field strength and the printing height satisfies the following formula:

[0146] ；

[0147] ;

[0148] ;

[0149] in, ξ k It refers to the hardening rate of 3D printed concrete. v It's printing speed. h It refers to the printing height of 3D printed concrete. l It is the length of a single-layer printing strip along the printing direction. μ 0 is the permeability in a vacuum. n It is the number of turns of the coil. I It depends on the magnitude of the coil current. b i It is the unit vector of the i-th micro magnetic field generator. r It is the distance from the magnetic field source. V Let be the volume of the magnetic material in the 3D-printed concrete, and ▽(MB) be the dot product of the magnetic moment and the gradient of the magnetic field at that point. μ s It is the static friction coefficient between 3D printed concrete and the printed working surface. F s It is the static friction between the 3D printed concrete and the printing surface. δ It refers to the horizontal deformation of 3D-printed concrete. ρ The average density of the slurry, g It is the acceleration due to gravity. h For printing height, K This is the lateral overturning force reduction factor.

[0150] For details, see Figures 3 to 5 The magnetic force analysis of concrete during the printing process is as follows:

[0151] A miniature magnetic field generating array, where the magnetic field strength of the miniature magnetic field generator is controlled by the current intensity of the energized solenoid, thereby forming a uniform magnetic field that can be intelligently adjusted according to the hardening state of the printed sample. Based on the nonlinear hardening process of the printed sample, its stiffness undergoes a time-varying evolution function. K ( t This can be represented as:

[0152] ;

[0153] in, ξ k It is the hardening rate. t It is the hardening time. It is the initial stiffness.

[0154] Regarding the magnetic field strength of the aforementioned micro-magnetic field generator, if a Cartesian coordinate system is established with the plane where the micro-magnetic field generator is located, then the magnetic field strength generated by a single micro-magnetic field generator is... B 0 can be represented as:

[0155] ;

[0156] in, μ 0 is the permeability in a vacuum. n It is the number of turns of the coil. I It is determined by the magnitude of the coil current.

[0157] For the aforementioned micro-magnetic field generating array, the contribution of the magnetic field source array formed by the individual micro-magnetic field generators to the total magnetic field needs to be considered. Since the direction and intensity of each magnetic field source are known, the total magnetic field intensity is determined by the principle of vector addition. B s It can be represented as:

[0158] ;

[0159] in, B i It is the magnetic field strength of the i-th micro magnetic field generator. b i It is the unit vector of the i-th micro magnetic field generator.

[0160] Concrete is subjected to magnetic force in a uniform magnetic field generated by a miniature magnetic field generator. Assume the distance between the concrete and the magnetic field generator is... r Then the magnetic field strength at that location B r With distance r The change can be represented as:

[0161] ;

[0162] in, r It is the distance from the magnetic field source.

[0163] Magnetic force on concrete at this location F m It can be represented as:

[0164] ;

[0165] in, B r V is the magnetic field strength at the location of the 3D printed concrete, V is the volume of the magnetic material in the 3D printed sample, and ▽(MB) is the dot product of the magnetic moment and the gradient of the magnetic field at that point.

[0166] The forces acting on the concrete in the magnetic field should conform to Newton's second law. Therefore, the equilibrium equation satisfying Newton's second law can be expressed as:

[0167] ;

[0168] in, It refers to the magnetic force exerted on 3D-printed concrete at a certain location. μ s It is the static friction coefficient between 3D printed concrete and the printed working surface. F s It is the static friction between the 3D printed concrete and the printing surface. m It is the total mass of the 3D-printed concrete. a It is the acceleration of motion.

[0169] In summary, based on the aforementioned time-varying stiffness evolution function K ( t and total magnetic field strength B s It can be seen that the control system of the magnetic field generator should control the total magnetic field strength in accordance with the time-varying hardening characteristics of the printed sample. According to the equilibrium equation, the total magnetic field strength should be determined by the current I through each micro magnetic field generator coil, the number of coil turns n, the distance r between the printed sample and the magnetic field source, and so on. Then, the magnetic control equation of the printed sample can be obtained by Maxwell's equations and the fluid Bingham model. F ( I ):

[0170] ;

[0171] in, ξ k It is the hardening rate. t It is the hardening time. μ 0 is the permeability in a vacuum. n It is the number of turns of the coil. I It depends on the magnitude of the coil current. b i It is the unit vector of the i-th micro magnetic field generator. r It is the distance from the magnetic field source. V denoted as , where ▽(MB) is the volume of the magnetic material in the 3D-printed sample, and ∠(MB) is the dot product of the magnetic moment and the gradient of the magnetic field at that point. μs It is the static friction coefficient between 3D printed concrete and the printed working surface. F s It is the static friction between the 3D printed concrete and the printing surface. δ It refers to the horizontal deformation of the printed sample.

[0172] As 3D-printed concrete accumulates layer by layer, the upper layers exert vertical pressure on the lower layers, causing the lower layers to deform horizontally. This horizontal deformation accumulates from bottom to top, eventually exceeding the lateral deformation and overturning limit of the 3D-printed concrete, leading to the collapse of the printed sample. Therefore, the aforementioned magnetic control equations... F ( I This technology can effectively prevent deformation of the underlying printing strips while applying controllable magnetic force to enhance the constructability of 3D printed concrete structures. The printing height is determined by the printing speed and strip length. h This can be expressed by a functional relationship as follows:

[0173] ;

[0174] in, t n It is the time it takes for the printing equipment to run up to time n. t 0 represents the time when the printing equipment begins to extrude concrete onto the printing platform. v It's printing speed. l It is the length of a single-layer printing strip along the printing direction.

[0175] Then the magnetic control equation F ( I It can be deformed to match the printing height. h Related functions F ( h ):

[0176] ；

[0177] Based on the relationship between lateral pressure and vertical compressive stress in the template according to Janssen's theory, the lateral overturning force of 3D-printed concrete is derived by analogy. P ( h The functional relationship between the print height and the print height is as follows:

[0178] ;

[0179] in, ρ To determine the average density of the printing paste, g It is the acceleration due to gravity. h For printing height, KThis is the lateral overturning force reduction factor.

[0180] By the principle of torque balance, we can obtain:

[0181] ;

[0182] Based on the balance between the magnetic force and the lateral overturning force, the control unit can perform real-time calculations and feedback to provide a stable and controllable external magnetic field, preventing the 3D printed concrete from undergoing horizontal deformation and overturning.

[0183] Each of the above implementation methods can be implemented individually, or in any combination of two or more.

[0184] The above implementation methods will be described in more detail below with reference to specific embodiments.

[0185] Example 1

[0186] To achieve a higher number of printable concrete layers, a stable printing process, and excellent mechanical properties of concrete, this embodiment provides a magnetic field-controlled 3D concrete printing device. The structure of this device can be found in [link to relevant documentation]. Figures 1 to 8 As shown, it includes:

[0187] The printing unit 1 includes a printing platform 101 and a printing device body 102 disposed above the printing platform 101;

[0188] Magnetic field unit 2, which is used to apply magnetic force to the concrete on the printing platform 101; and

[0189] The control unit 3 includes a printing control component 301 connected to the printing unit 1 and used to control the extrusion of concrete by the printing device body 102, and a magnetic field control component 302 connected to the magnetic field unit 2.

[0190] As the height of the concrete gradually increases, magnetic field unit 2 applies magnetic force to the concrete to prevent it from overturning.

[0191] Please see again. Figures 1 to 8 As shown, magnetic field unit 2 includes:

[0192] Roller electrode plates 201 with adjustable height are located on both sides of the printing platform 101;

[0193] Identification element 202 is located at the upper end of the roller shutter electrode plate 201;

[0194] And a plurality of miniature magnetic field generating arrays 203 disposed on the side of the roller shutter electrode plate 201 facing the printing platform 101;

[0195] The identification component 202 identifies the hardening state and deformation of the concrete and sends a signal to the magnetic field control component 302. The magnetic field control component 302 applies a magnetic force to the concrete to prevent it from overturning.

[0196] The roller shutter electrode plate 201 has electric shock protection, and a hot-swappable circuit board is provided at the end of the roller shutter electrode plate 201 facing the printing unit 1. The hot-swappable circuit board is used to install the micro magnetic field generating array 203. The roller shutter electrode plate 201 rises with the increase of the number of concrete layers, so that concrete of different layer heights can be covered by a stable magnetic field.

[0197] The micro magnetic field generating array 203 is composed of multiple micro magnetic field generators arranged in a row. Each micro magnetic field generator has a diameter of 1-3 mm and is made of nano copper wire coated with an insulating coating wound around the surface of a cylinder. It is installed on a hot-swappable circuit board on the inner surface of the flexible roller shutter electrode plate according to the array arrangement position, facing the direction of the printing unit 1. The micro magnetic field generating array is connected to the hot-swappable circuit board.

[0198] The identification component 202 can monitor the strip hardening, strip appearance, structural deformation, structural thermal field distribution, and structural cracking defects in real time during the concrete printing process. It can also identify and process the above images to obtain the time-varying hardening state of the strip in different printing layers, and generate real-object photographs and binarized grayscale images. After the grayscale images are converted and processed, they are fed back to the magnetic field control component 302 to adjust the magnetic field strength at different printing layer positions, so that the strip is balanced in the horizontal direction in the magnetic field and does not cause volume deformation of the strip in the horizontal direction.

[0199] Please see again. Figure 1 As shown, the height of the roller shutter electrode plate 201 is controlled by the printing control unit 301 to ensure that the roller shutter electrode plate 201 is at the same height as the concrete extruded by the printing unit 1.

[0200] Please see again. Figure 1 As shown, the micro magnetic field generating array 203 is uniformly distributed along the height direction of the roller shutter electrode plate 201.

[0201] Please see again. Figure 8 As shown, the identification element 202 includes:

[0202] The movable guide rail 204 is located at the upper end of the roller shutter electrode plate 201, and the movable guide rail 204 is equipped with several low friction bearings 205.

[0203] Stabilizer 206 located on the upper surface of the moving guide rail 204;

[0204] A rectangular mounting cavity 207 is located on the upper surface of the stabilizer 206;

[0205] A horizontal calibrator 208 is installed inside the mounting cavity 207;

[0206] A laser positioning device 209 is installed inside the mounting cavity 207;

[0207] Thermal imager 210 is installed inside the mounting cavity 207;

[0208] A high-precision camera 211 is located inside the mounting cavity 207 and next to the thermal imager 210;

[0209] And a lens protection plate 212 that covers the outer surface of the thermal imager 210 and the high-precision camera 211.

[0210] Please see again. Figure 1 and Figure 8 As shown, printing unit 1 includes:

[0211] The slurry feeding component 103, which is connected to an external slurry feeding device and located on top of the printing device body 102, includes a plurality of feeding hoses 108 connected to the external slurry feeding device and a speed controller 109 located among the plurality of feeding hoses 108.

[0212] A spiral blade extrusion controller 104 connected to the slurry feeder 103;

[0213] The stress sensor 105 is located between the spiral blade extrusion controller 104 and the slurry feeder 103, and is located at the front end of the speed controller 109 and abuts against the spiral blade extrusion controller 104.

[0214] Printing nozzle 106 connected to spiral blade extrusion controller 104;

[0215] The printing unit also includes a magnetic material feeder 107 connected to the printing nozzle 106 and to an external magnetic material feeding device. The printing nozzle 106 sprays magnetic material onto the concrete to satisfy the magnetic field unit 2 applying magnetic force to the concrete.

[0216] Please see again. Figure 1 and Figure 8 As shown, the spiral blade extrusion controller 104 includes:

[0217] The transmission rod 110 is connected to the speed controller 109;

[0218] And the helical blades 111 that spiral around the outer surface of the transmission rod 110;

[0219] As the slurry is driven to the printing nozzle 106 by the spiral blade 111, the stress sensor 105 transmits the rheological parameters of the slurry and sends a signal to the printing control unit 301 so that the printing control unit 301 can control the rotation speed of the speed controller 109.

[0220] Example 2

[0221] This embodiment provides a printing method, which is executed by a magnetic field-controlled 3D concrete printing device as described in Embodiment 1. The steps are detailed below. Figure 8 As shown, the printing method includes the following steps:

[0222] S1: Obtain the concrete printing structure and input it into the printing control unit 301;

[0223] S2: The slurry feeding device and the magnetic material feeding device feed the printing unit 1. The slurry feeding device 103 sends a signal to the printing control device 301. The printing control device 301 controls the speed controller 109 to start printing. The stress sensor 105 transmits the rheological parameters of the slurry and sends a signal to the printing control device 301. When the slurry is extruded to the printing platform 101, the printing nozzle 106 sprays the magnetic material onto the outer surface of the concrete.

[0224] Specifically, as the printing time increases, the stress sensor 105 in the spiral blade extrusion controller 104 detects that the rheological parameters of the slurry change over time, the slurry viscosity increases, the yield stress increases, and the speed controller starts to increase the motor power to keep the spiral blade speed constant until the printed sample is prepared.

[0225] S3: Concrete accumulates layer by layer on the printing platform 101. As the roller shutter electrode plate 201 rises, the identification component 202 identifies the concrete information and sends a signal to the magnetic field control component 302. The magnetic field control component 302 controls the magnetic field strength generated by the micro magnetic field generating array 203 to prevent the concrete from overturning.

[0226] Specifically, as the concrete is accumulated layer by layer, the roller shutter electrode plate 201 changes with height. At this time, the identification component 202 provides real-time feedback of monitoring data based on the time-varying hardening state of the printed sample, and the magnetic field control component 302 gradually increases the coil current intensity of the micro magnetic field generator, so that the magnetic force on the concrete gradually increases with the increase of sample height and the extension of extrusion time, maintaining its force balance.

[0227] S4: Printing complete. Curing of the concrete.

[0228] Please see again. Figure 9 As shown, in step S3, the magnetic field control unit 302 controls the micro magnetic field generating array 203 to gradually increase the magnetic field strength generated by the printed concrete as the 3D printed concrete hardens, so as to ensure that the printed concrete does not undergo horizontal deformation. The magnetic force provided by the magnetic field strength satisfies the following formula:

[0229]

[0230] in, It refers to the hardening rate of 3D printed concrete. t It refers to the hardening time of 3D-printed concrete. μ 0 is the permeability in a vacuum. n It is the number of turns of the coil. I It depends on the magnitude of the coil current. b i It is the unit vector of the i-th micro magnetic field generator. r It is the distance from the magnetic field source. V Let be the volume of the magnetic material in the 3D-printed concrete, and ▽(MB) be the dot product of the magnetic moment and the gradient of the magnetic field at that point. μ s It is the static friction coefficient between 3D printed concrete and the printed working surface. F s It is the static friction between the 3D printed concrete and the printing platform. δ It refers to the horizontal deformation of 3D printed concrete.

[0231] Please see again. Figure 9 As shown, the magnetic field strength generated by the micro magnetic field generating array 203 controlled by the magnetic field control component 302 provides a magnetic force to the 3D printed concrete that satisfies the torque balance of the lateral overturning force distributed along the printing height of the 3D printed concrete. The relationship between the magnetic force provided by the magnetic field strength and the printing height satisfies the following formula:

[0232] ；

[0233] ;

[0234] ;

[0235] in, It refers to the hardening rate of 3D printed concrete. v It's printing speed. h It refers to the printing height of 3D printed concrete. l It is the length of a single-layer printing strip along the printing direction. μ 0 is the permeability in a vacuum. n It is the number of turns of the coil. I It depends on the magnitude of the coil current. b i It is the unit vector of the i-th micro magnetic field generator. r It is the distance from the magnetic field source. V Let be the volume of the magnetic material in the 3D-printed concrete, and ▽(MB) be the dot product of the magnetic moment and the gradient of the magnetic field at that point. μ s It is the static friction coefficient between 3D printed concrete and the printed working surface. F sIt is the static friction between the 3D printed concrete and the printing surface. δ It refers to the horizontal deformation of 3D-printed concrete. ρ The average density of the slurry, g It is the acceleration due to gravity. h For printing height, K This is the lateral overturning force reduction factor.

[0236] See Figures 3 to 5 The magnetic force analysis of concrete during the printing process is as follows:

[0237] A miniature magnetic field generating array, where the magnetic field strength of the miniature magnetic field generator is controlled by the current intensity of the energized solenoid, thereby forming a uniform magnetic field that can be intelligently adjusted according to the hardening state of the printed sample. Based on the nonlinear hardening process of the printed sample, its stiffness undergoes a time-varying evolution function. K ( t This can be represented as:

[0238] ;

[0239] in, It is the hardening rate. t It is the hardening time. It is the initial stiffness.

[0240] For the magnetic field strength of a micro magnetic field generator, if a Cartesian coordinate system is established with the plane where the micro magnetic field generator is located, then the magnetic field strength generated by a single micro magnetic field generator is... B 0 can be represented as:

[0241] ;

[0242] in, It is the magnetic permeability in a vacuum. n It is the number of turns of the coil. I It is determined by the magnitude of the coil current.

[0243] For a micro magnetic field generating array, the contribution of each individual micro magnetic field generator to the total magnetic field needs to be considered. Since the direction and intensity of each magnetic field source are known, the total magnetic field strength can be calculated using the vector addition principle. B s It can be represented as:

[0244] ;

[0245] in, B i It is the magnetic field strength of the i-th micro magnetic field generator. b i It is the unit vector of the i-th micro magnetic field generator.

[0246] Concrete is subjected to magnetic force in a uniform magnetic field generated by a miniature magnetic field generator. Assume the distance between the concrete and the magnetic field generator is... r Then the magnetic field strength at that location B r With distance r The change can be represented as:

[0247] ;

[0248] Where r is the distance from the magnetic field source.

[0249] Magnetic force on concrete at this location F m It can be represented as:

[0250] ;

[0251] in, It is the magnetic field strength at the location of the 3D-printed concrete. V is the volume of the magnetic material in the 3D printed sample, and ▽(MB) is the dot product of the magnetic moment and the magnetic field gradient at that point.

[0252] The forces acting on the concrete in the magnetic field should conform to Newton's second law. Therefore, the equilibrium equation satisfying Newton's second law can be expressed as:

[0253] ;

[0254] in, F m It refers to the magnetic force exerted on 3D-printed concrete at a certain location. μ s It is the static friction coefficient between 3D printed concrete and the printed working surface. F s It is the static friction between the 3D printed concrete and the printing surface. m It is the total mass of the 3D-printed concrete. a It is the acceleration of motion.

[0255] In summary, based on the time-varying evolution function of stiffness K ( t and total magnetic field strength B s It can be seen that the control system of the magnetic field generator should control the total magnetic field strength in accordance with the time-varying hardening characteristics of the printed sample. According to the equilibrium equation, the total magnetic field strength should be determined by the current passing through the coil of each miniature magnetic field generator. I Number of coil turns n The distance between the printed sample and the magnetic field source rThen, using Maxwell's equations and the Bingham fluid model, the magnetic control equations for the printed sample can be obtained. F ( I ):

[0256] ；

[0257] in, It refers to the hardening rate of 3D printed concrete. t It refers to the hardening time of 3D-printed concrete. μ 0 is the permeability in a vacuum. n It is the number of turns of the coil. I It depends on the magnitude of the coil current. b i It is the unit vector of the i-th micro magnetic field generator. r It is the distance from the magnetic field source. V Let be the volume of the magnetic material in the 3D-printed concrete, and ▽(MB) be the dot product of the magnetic moment and the gradient of the magnetic field at that point. μ s It is the static friction coefficient between 3D printed concrete and the printed working surface. F s It is the static friction between the 3D printed concrete and the printing platform. δ It refers to the horizontal deformation of 3D printed concrete.

[0258] As 3D-printed concrete accumulates layer by layer, the upper layers exert vertical pressure on the lower layers, causing horizontal deformation. This horizontal deformation accumulates from bottom to top, eventually exceeding the lateral deformation and overturning limit of the printed concrete, leading to the collapse of the printed sample. Therefore, by using the aforementioned magnetic control equation F(t), a controllable magnetic force can be applied to improve the constructability of 3D-printed concrete structures while effectively preventing deformation of the bottom printing layers. The printing height is determined by the printing speed and the strip length. h This can be expressed by a functional relationship as follows:

[0259] ;

[0260] in, t n It is the time it takes for the printing equipment to run up to time n. t 0 represents the time when the printing equipment begins to extrude concrete onto the printing platform. l It is the length of a single-layer printing strip along the printing direction.

[0261] Then the magnetic control equation F ( I It can be deformed to match the printing height.h Related functions F ( h ):

[0262] ；

[0263] Based on the relationship between lateral pressure and vertical compressive stress in the template according to Janssen's theory, the lateral overturning force of 3D-printed concrete is derived by analogy. P ( h The functional relationship between the print height and the print height is as follows:

[0264] ;

[0265] in, ρ To determine the average density of the printing paste, g It is the acceleration due to gravity. h For printing height, K This is the lateral overturning force reduction factor.

[0266] By the principle of torque balance, we can obtain:

[0267] ;

[0268] Based on the balance between magnetic force and lateral overturning force, the control unit can perform real-time calculations and feedback to provide a stable and controllable external magnetic field, preventing 3D printed concrete from undergoing horizontal deformation and overturning.

[0269] Experimental Example 1

[0270] This Experiment 1 was performed according to Examples 1 to 2, providing a method for 3D printing concrete with sprayed magnetic material.

[0271] The 3D printed concrete, by weight, comprises the following components: 1000 parts cement, 1000 parts fine aggregate, 1.28 parts water-retaining agent, 0.31 parts water-reducing agent, 0.7 parts retarder, 5.8 parts thickener, and 536 parts water, which are mixed to obtain a slurry.

[0272] The obtained slurry is fed into the slurry feeding device and supplied to printing unit 1. Under the control of electronic equipment, printing unit 1 extrudes layer by layer according to the set method, with a horizontal printing speed of 2000 mm / min and a layer thickness of 15 mm. Meanwhile, the magnetic material feeding device supplies magnetic material to the printing nozzle 105 and sprays it onto the concrete, accumulating layer by layer to obtain sample 1#. After printing, sample 1# is coated with a protective film and, after hardening, is placed in an environment with a temperature of 20 degrees Celsius and a humidity of 95% for curing for 28 days.

[0273] Experimental Example 2

[0274] This Experiment 2 was performed according to Examples 1 to 2, and provides a 3D printed concrete with direct addition of magnetic materials. The difference between this Experiment 2 and Example 1 is the different way the magnetic materials are incorporated.

[0275] 3D printed concrete, by weight, comprises the following components: 1000 parts cement, 1000 parts fine aggregate, 30 parts magnetic material, 1.28 parts water-retaining agent, 0.31 parts water-reducing agent, 0.7 parts retarder, 5.8 parts thickener, and 536 parts water, which are mixed to obtain a slurry.

[0276] The obtained slurry is fed into the slurry feeding device and then fed to printing unit 1. Under the control of electronic equipment, printing unit 1 extrudes layer by layer according to the set method, with a layer thickness of 15mm. At this time, the printing nozzle 105 does not spray magnetic material. Through layer accumulation, sample 2# is obtained. After sample 2# is printed, it is coated with a protective film and, after hardening, placed in an environment with a temperature of 20 degrees Celsius and a curing humidity of 95% for 28 days.

[0277] Comparative Test Example 1

[0278] Compared with Test Example 1, this comparative test example 1 uses a commercially available concrete 3D printing equipment, and all other conditions are the same.

[0279] Comparative Test Example 2

[0280] Compared with Test Example 1, this comparative test example 2 uses a commercially available concrete 3D printing equipment, and all other conditions are the same except that the weight of water is 475 parts.

[0281] Comparative Test Example 3

[0282] Compared with Test Example 2, this comparative test example 3 uses a commercially available concrete 3D printing equipment, with other conditions being the same.

[0283] Comparative Test Example 4

[0284] Compared with Test Example 2, this comparative test example 4 uses a commercially available concrete 3D printing equipment, and all other conditions are the same except that the weight of water is 495 parts.

[0285] The magnetic field strength parameters, constructability, and compressive strength test results of the above-mentioned printed samples are shown in Table 1.

[0286]

[0287] As shown in the table, Experimental Examples 1 and 2, using the device and printing method of the present invention, can improve the constructability of 3D printed structures. In Experimental Examples 1 and 2, no collapse occurred after printing 50 layers. In contrast, Comparative Examples 1 and 2, which did not use the device of the present invention, collapsed at the 17th and 19th layers, respectively. Comparative Examples 3 and 4 collapsed at the 18th and 21st layers, respectively. During the testing, a Hall effect magnetometer was used to measure the magnetic field strength at the center of the printed strip. It was found that the micro-magnetic field generator in Experimental Example 2 produced a lower magnetic field strength. This is because when magnetic materials are directly added to concrete, the total volume of the magnetic material is higher than that of the spraying method. The magnetic material in Experimental Example 2 contributed a higher magnetic force. Therefore, after correction by the identification element, the current flowing through the micro-magnetic field array was reduced, balancing the forces on the concrete printed strip in the magnetic field. During the printing process, as demonstrated in Example 1, whether magnetic materials are sprayed or directly added to the concrete, the stability of the concrete construction can be achieved during the printing process, and there is no significant adverse effect on the mechanical properties of the printed sample.

[0288] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0289] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A magnetic field-controlled 3D-printed concrete constructability lifting device, characterized in that, include: The printing unit (1) includes a printing platform (101) and a printing device body (102) arranged above the printing platform (101). Magnetic field unit (2), which is used to apply magnetic force to the concrete on the printing platform (101); and The control unit (3) includes a printing control unit (301) connected to the printing unit (1) and used to control the printing device body (102) to extrude concrete, and a magnetic field control unit (302) connected to the magnetic field unit (2). As the height of the concrete gradually increases, the magnetic field unit (2) applies a magnetic force to the concrete to prevent it from overturning. The magnetic field unit (2) includes: Roller electrode plates (201) are located on both sides of the printing platform (101) and are height adjustable. An identification element (202) is provided on the upper end of the roller shutter electrode plate (201); And a plurality of micro magnetic field generating arrays (203) disposed on the side of the roller shutter electrode plate (201) facing the printing platform (101); The identification element (202) identifies the hardening state and deformation of the concrete and sends a signal to the magnetic field control element (302), which applies a magnetic force to the concrete to prevent it from overturning.

2. The magnetic field-controlled 3D printed concrete constructability lifting device according to claim 1, characterized in that, The height of the roller shutter electrode plate (201) is controlled by the printing control unit (301) to ensure that the roller shutter electrode plate (201) is at the same height as the concrete extruded by the printing unit (1).

3. The magnetic field-controlled 3D printed concrete constructability lifting device according to claim 2, characterized in that, The micro magnetic field generating array (203) is uniformly distributed along the height direction of the roller shutter electrode plate (201).

4. The magnetic field-controlled 3D printed concrete constructability lifting device according to claim 1, characterized in that, The identification element (202) includes: The movable guide rail (204) is located at the upper end of the roller shutter electrode plate (201), and the movable guide rail (204) is provided with several low friction bearings (205). Stabilizer (206) located on the upper surface of the moving guide rail (204); A rectangular mounting cavity (207) is located on the upper surface of the stabilizer (206). A leveling instrument (208) is installed inside the mounting cavity (207); A laser positioning device (209) is installed inside the mounting cavity (207); A thermal imager (210) is installed inside the mounting cavity (207); A high-precision camera (211) is located inside the mounting cavity (207) and next to the thermal imager (210). And a lens protection plate (212) covering the outer surface of the thermal imager (210) and the high-precision camera (211).

5. A magnetic field-controlled 3D-printed concrete constructability lifting device according to claim 1, characterized in that, The printing unit (1) includes: The slurry feeding device (103) is connected to an external slurry feeding device and located on top of the printing device body (102). It includes a plurality of feeding hoses (108) connected to the external slurry feeding device and a speed controller (109) located between the plurality of feeding hoses (108). A spiral blade extrusion controller (104) connected to the slurry feeder (103). A stress sensor (105) is located between the spiral blade extrusion controller (104) and the slurry feeder (103), and is disposed at the front end of the speed controller (109) and abuts against the spiral blade extrusion controller (104). Printing nozzle (106) connected to the spiral blade extrusion controller (104). The printing unit also includes a magnetic material feeder (107) connected to the printing nozzle (106) and to an external magnetic material feeding device, wherein the printing nozzle (106) sprays magnetic material onto the concrete to satisfy the magnetic field unit (2) applying magnetic force to the concrete.

6. The magnetic field-controlled 3D-printed concrete constructability lifting device according to claim 5, characterized in that, The spiral blade extrusion controller (104) includes: The transmission rod (110) is connected to the speed controller (109). And a helical blade (111) that spirals around the outer surface of the transmission rod (110). As the slurry is driven to the printing nozzle (106) by the spiral blade (111), the stress sensor (105) transmits the rheological parameters of the slurry and sends a signal to the printing control unit (301) so that the printing control unit (301) can control the rotation speed of the speed controller (109).

7. A magnetic field-controlled method for improving the constructability of 3D-printed concrete, performed by a magnetic field-controlled 3D-printed concrete constructability improvement device according to any one of claims 1-6, characterized in that, The method includes the following steps: S1: Obtain the concrete printing structure and input it into the printing control unit (301); S2: The slurry feeding device and the magnetic material feeding device feed the printing unit (1). The slurry feeding device (103) sends a signal to the printing control device (301). The printing control device (301) controls the speed controller (109) to start printing. The stress sensor (105) transmits the rheological parameters of the slurry and sends a signal to the printing control device (301). When the slurry is extruded to the printing platform (101), the printing nozzle (106) sprays magnetic material onto the outer surface of the concrete. S3: Concrete accumulates layer by layer on the printing platform (101). As the roller electrode plate (201) rises, the identification component (202) identifies the concrete information and sends a signal to the magnetic field control component (302). The magnetic field control component (302) controls the magnetic field strength generated by the micro magnetic field generating array (203) to prevent the concrete from overturning. S4: Printing complete. Curing of the concrete.

8. The method for improving the constructability of 3D printed concrete under magnetic field control according to claim 7, characterized in that, In step S3, the magnetic field control unit (302) controls the micro magnetic field generating array (203) to gradually increase the magnetic field strength generated in the printed concrete as the 3D printed concrete hardens, so that the printed concrete does not undergo horizontal deformation. The magnetic force provided by the magnetic field strength satisfies the following formula: ； in, It refers to the hardening rate of 3D printed concrete. t It refers to the hardening time of 3D-printed concrete. μ 0 is the permeability in a vacuum. n It is the number of turns of the coil. I It depends on the magnitude of the coil current. b i is the unit vector of the i-th micro magnetic field generator, and r is the distance from the magnetic field source. V It is the volume of the magnetic material in 3D-printed concrete. It is the dot product of the magnetic moment and the gradient of the magnetic field at that point. It is the static friction coefficient between 3D printed concrete and the printed working surface. F s It is the static friction between the 3D printed concrete and the printing platform. It refers to the horizontal deformation of 3D printed concrete.

9. The method for improving the constructability of 3D printed concrete under magnetic field control according to claim 7, characterized in that, The magnetic field control unit (302) controls the magnetic field strength generated by the micro magnetic field generating array (203) to satisfy the torque balance of the lateral overturning force distributed along the printing height of the 3D printed concrete. The relationship between the magnetic force provided by the magnetic field strength and the printing height satisfies the following formula: ； ； ； in, It refers to the hardening rate of 3D printed concrete. v It's printing speed. h It refers to the printing height of 3D printed concrete. l It is the length of a single-layer printing strip along the printing direction. μ 0 is the permeability in a vacuum. n It is the number of turns of the coil. I It depends on the magnitude of the coil current. b i It is the unit vector of the i-th micro magnetic field generator. r It is the distance from the magnetic field source. V It is the volume of the magnetic material in 3D-printed concrete. It is the dot product of the magnetic moment and the gradient of the magnetic field at that point. It is the static friction coefficient between 3D printed concrete and the printed working surface. F s It is the static friction between the 3D printed concrete and the printing surface. It refers to the horizontal deformation of 3D-printed concrete. ρ The average density of the slurry, g It is the acceleration due to gravity. h For printing height, K This is the lateral overturning force reduction factor.

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