3D printing equipment based on construction waste recycled aggregate and construction method

Abstract

The invention discloses 3D printing equipment based on construction waste recycled aggregate and a construction method, and belongs to the technical field of building 3D printing. According to the technical scheme, the 3D printing equipment based on the construction waste recycled aggregate comprises a vertical lifting mechanism, a containing area for containing a reinforcing mesh part is arranged in the middle of the vertical lifting mechanism, an annular frame body is slidably connected to the vertical lifting mechanism, and an annular storage mechanism is arranged above the annular frame body; an annular sliding rail is arranged below the annular frame body, and a printing assembly is slidably connected to the annular sliding rail. Through cooperative control of the vertical lifting mechanism and the annular sliding rail, in combination with the printing assembly with the switchable position and the intelligent material supplementing system, accurate printing and automatic material supplementing of the inner side and the outer side of the reinforcing mesh are achieved, the technical problems that in traditional printing, a protective layer is not uniform, and the material supplementing efficiency is low are solved, and the printing efficiency is improved. The method has the remarkable advantages of improving the structural strength, optimizing resource utilization and improving the construction efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of building 3D printing, and in particular relates to a 3D printing device and a construction method based on recycled aggregates from construction waste. Background Art

[0002] As the modern construction industry continues to boom, the amount of construction waste generated is increasing rapidly. According to relevant data, China's annual construction waste discharge exceeds 1.5 billion tons, with an average annual growth rate of 8%. By 2020, it had exceeded 3 billion tons, accounting for approximately 40% of total urban waste. However, its resource utilization rate is less than 10%. Large amounts of construction waste are not effectively treated and are often transported to suburban areas or urban areas for simple landfill or open-air storage. This not only occupies a large amount of valuable land resources but also causes serious pollution to the ecological environment.

[0003] At the same time, with the continued expansion of the construction industry, demand for sand and gravel aggregates has skyrocketed. For a long time, due to the relative ease and low price of sand and gravel aggregates, people have been indiscriminately exploiting them, leading to a series of serious ecological problems such as resource depletion, landslides, and riverbed diversion, and greatly damaging the natural environment. In this context, processing construction waste into recycled aggregates and utilizing them has become a key measure to conserve resources, protect the environment, and promote the sustainable development of the construction industry.

[0004] 3D printing, a highly innovative manufacturing technology, has been gaining prominence in the architectural field in recent years. Based on digital model files, it constructs three-dimensional objects by printing adhesive materials layer by layer. Compared with traditional manufacturing techniques, it offers significant advantages such as eliminating molds, reducing waste, and lowering inventory. It can effectively optimize building structures, conserve materials and energy, and significantly improve manufacturing efficiency, realizing the innovative concept of "design-driven manufacturing."

[0005] However, the existing 3D printing technology for construction still faces many technical bottlenecks in its application. First, when it comes to printing steel-reinforced structures, traditional equipment makes it difficult to achieve an organic combination of steel mesh and printing materials, resulting in insufficient strength of the printed structure. In particular, during the printing of concrete columns, the uniformity and integrity of the protective layer around the steel mesh cannot be guaranteed, seriously affecting the mechanical properties and durability of the components. Secondly, the material supply system of existing equipment is not intelligent enough, and cannot achieve accurate and automatic material replenishment according to the printing progress, which easily causes printing interruptions. In addition, the maintenance link after printing is completed lacks effective real-time maintenance methods, and the printed structure cannot be cured and solidified in time, affecting the final quality. These problems have seriously restricted the promotion and application of 3D printing technology for construction in engineering practice. Summary of the Invention

[0006] The present invention provides a 3D printing device and a construction method based on recycled aggregates from construction waste to solve at least one of the above technical problems.

[0007] The technical solution adopted in the present invention is: A 3D printing device based on recycled aggregates from construction waste, comprising a vertical lifting mechanism, a accommodating area for accommodating a steel mesh in the middle of the vertical lifting mechanism, a ring-shaped frame main body steel bar positioning hole slidably connected to the vertical lifting mechanism, a ring-shaped material storage mechanism is provided above the ring-shaped frame main body steel bar positioning hole, a ring-shaped slide rail steel bar positioning hole is provided below the ring-shaped frame main body steel bar positioning hole, a printing assembly is slidably connected to the ring-shaped slide rail steel bar positioning hole, a plurality of discharge port steel bar positioning holes are provided at the bottom of the material storage mechanism, a solenoid valve is provided on the discharge port steel bar positioning hole, a plurality of the discharge port steel bar positioning holes pass through the annular slide rail steel bar positioning hole and are arranged at equal intervals along the annular slide rail steel bar positioning hole, when the printing assembly slides to the discharge port steel bar positioning hole, the solenoid valve is opened to replenish material for the printing assembly, and the output end of the printing assembly is telescopically arranged so that it has a first position located outside the steel mesh and a second position located inside the steel mesh; It also includes a control system, which controls the opening or closing of the electromagnetic valve to achieve automatic material replenishment of the printing component, and the control system controls the output end of the printing component to automatically switch between a first position and a second position.

[0008] Furthermore, the present application also proposes that the printing component is initially in a first position and slides circumferentially along the steel bar positioning hole of the annular slide rail to print a protective layer on the outside of the steel mesh. When the height of the protective layer reaches a threshold, the printing component switches from the first position to the second position to pour material into the inside of the steel mesh.

[0009] Furthermore, the present application also proposes that the printing component includes a sliding part steel bar positioning hole that slides with the annular slide rail steel bar positioning hole, the upper end of the sliding part steel bar positioning hole is provided with a accommodating cavity steel bar positioning hole for accommodating materials, the lower end of the sliding part steel bar positioning hole is rotatably connected with the discharge pipe steel bar positioning hole, the side wall of the sliding part steel bar positioning hole is rotatably connected with the first telescopic cylinder steel bar positioning hole, the telescopic end of the first telescopic cylinder steel bar positioning hole is rotatably connected with the discharge pipe steel bar positioning hole, the lower end of the discharge pipe steel bar positioning hole is slidably connected with the telescopic tube steel bar positioning hole, a second telescopic cylinder steel bar positioning hole is provided between the telescopic tube steel bar positioning hole and the discharge pipe steel bar positioning hole, and the lower end of the telescopic tube steel bar positioning hole is provided with a material outlet steel bar positioning hole.

[0010] Furthermore, the present application also proposes that a material sensor for detecting the weight of the internal material is provided in the steel bar positioning hole of the accommodating cavity, and the displacement of the material in the sliding stroke of the steel bar positioning hole of the sliding part between two adjacent steel bar positioning holes of the discharge port is N. The material sensor detects that the material stock in the steel bar positioning hole of the accommodating cavity is M, and the maximum material capacity of the steel bar positioning hole of the accommodating cavity is 4-5N. When M=N, the steel bar positioning hole of the accommodating cavity moves to the steel bar positioning hole of the next discharge port for material replenishment.

[0011] Furthermore, the present application also proposes that it also includes a jet frame steel bar positioning hole that is slidably connected to the vertical lifting mechanism, and the jet frame steel bar positioning hole is located below the annular frame main body steel bar positioning hole, and is used to maintain and solidify the protective layer printed by the printing component. The jet frame steel bar positioning hole has an airflow cavity inside, and the inner wall of the jet frame steel bar positioning hole is provided with a jet hole, and the outer wall of the jet frame steel bar positioning hole is provided with a gas duct steel bar positioning hole for connecting to the output end of the external maintenance steam supply equipment, and the gas duct steel bar positioning hole is provided with an electric control valve.

[0012] Furthermore, the present application also proposes that the vertical lifting assembly includes a lifting guide rail steel bar positioning hole, the side wall of the annular frame main body steel bar positioning hole is provided with a first guide sliding member that slides with the lifting guide rail steel bar positioning hole, and the side wall of the jet frame steel bar positioning hole is provided with a second guide sliding member steel bar positioning hole that slides with the lifting guide rail steel bar positioning hole, and the lifting guide rail steel bar positioning hole is provided with a driving mechanism that drives the annular frame main body steel bar positioning hole and the jet frame steel bar positioning hole to rise and fall along the lifting guide rail steel bar positioning hole.

[0013] Furthermore, the present application also proposes that the annular material storage mechanism includes an annular groove steel bar positioning hole, the side wall of the annular groove steel bar positioning hole is provided with a feeding pipe steel bar positioning hole, and the top of the annular groove steel bar positioning hole is detachably connected to a cover plate steel bar positioning hole.

[0014] Furthermore, the present application also proposes that the upper end of the lifting guide rail steel bar positioning hole is slidingly connected with the vertical steel bar limiting plate steel bar positioning hole, and the vertical steel bar limiting plate steel bar positioning hole is provided with a plurality of steel bar positioning holes, and the lifting guide rail steel bar positioning hole is vertically spaced and fixedly connected with a plurality of reinforcing beam steel bar positioning holes.

[0015] A 3D printing construction method based on recycled aggregates from construction waste, specifically comprising the following steps: S1. Hoist and position the vertical lifting mechanism according to the position of the steel mesh; S2. Input the size and model parameters of the concrete column into the control system, and pour the casting material into the annular groove steel bar positioning hole; S3, the control system controls the steel bar positioning hole of the sliding part to slide to the position directly below the nearest steel bar positioning hole of the discharge port, and controls the solenoid valve of the steel bar positioning hole of the discharge port to open to fill the steel bar positioning hole of the accommodating cavity with material, and the solenoid valve closes after the filling is completed; S4. The control system controls the output end of the printing assembly to be in the first position, and the steel bar positioning holes of the sliding part slide circumferentially along the steel bar positioning holes of the annular slide rail and perform the nesting printing action, stacking the material layer by layer along the outside of the steel mesh to print the outer protective layer of the concrete column. The control system controls the steel bar positioning holes of the annular frame body to rise as the height of the protective layer increases; S5. The reinforcement positioning holes of the jet frame are connected to the output end of the external curing steam supply equipment through the gas conduit reinforcement positioning holes. The control system controls the electric control valve to open, and the jet holes of the jet frame reinforcement positioning holes spray steam of appropriate temperature to cure the protective layer; S6. The steel bar positioning hole of the sliding part slides directly below any steel bar positioning hole of the discharge port, and the control system controls the solenoid valve of the steel bar positioning hole of the discharge port to open. The control system controls the output end of the printing component to be in the second position, and the material is poured into the internal space of the protective layer; S7. After the printing height reaches the preset value, the construction of a single concrete column is completed, and the vertical lifting mechanism is hoisted to the next construction area.

[0016] Furthermore, the present application also proposes that, in step S5, a jet time threshold is set. After the threshold is reached, the control system controls the jet frame steel bar positioning holes to rise to perform jet maintenance on the upper protective layer.

[0017] Due to the adoption of the above technical solution, the beneficial effects achieved by the present invention are as follows: 1. This application provides a stable installation space for steel mesh through the design of the accommodation area of ​​the vertical lifting mechanism; the cooperation of the annular storage mechanism with the annular slide rail steel bar positioning holes and the printing assembly realizes the automatic replenishment of materials; the application of the control system realizes the automatic operation of the equipment, effectively solving the above problems.

[0018] Through the above technical solution, this application achieves precise matching of steel mesh positioning and printing path, ensuring the uniformity and integrity of the concrete cover. The automatic refill system eliminates the risk of printing interruptions, seamlessly integrating the outer protective layer printing with the internal filling process. The dual-position working mode of the retractable printing component effectively solves the problem of simultaneous forming of the inner and outer layers of reinforced structures, improving structural integrity and construction efficiency.

[0019] 2. The scheme triggers an automatic switching mechanism by setting a height threshold, enabling the printing assembly to complete the outer protective layer printing and internal material pouring in a single cycle, avoiding errors caused by multiple positioning, and ensuring the uniformity of the protective layer thickness through a closed-loop control system. The continuous automatic printing of the inner and outer layers of the reinforcement mesh is realized, solving the problem of insufficient bonding strength caused by the separate pouring of the protective layer and the internal structure in traditional processes. The position switching mechanism triggered by the height threshold ensures that the protective layer reaches the designed thickness and immediately enters the internal pouring stage, avoiding material waste or structural defects caused by human judgment errors. In addition, the coordinated control of the circumferential sliding and position switching significantly improves the forming efficiency of complex reinforcement structures, especially suitable for batch construction of large-diameter concrete columns.

[0020] 3. The scheme realizes the dual adjustment of the material outlet direction and height through the rotation of the reinforcement positioning hole of the discharge pipe and the telescopic pipe reinforcement positioning hole structure, solving the technical problem of synchronous pouring of the inner and outer reinforcement mesh. The application realizes the precise positioning and pouring of the printing assembly in the inner and outer space of the reinforcement mesh, ensuring the continuous forming of the protective layer and the internal structure. The height-adjustable feature of the material outlet reinforcement positioning hole avoids the blockage of the outlet caused by the change of the printing layer height, the rotation adjustment mechanism improves the adaptability to different diameter reinforcement meshes, and the nested telescopic pipe reinforcement positioning hole structure effectively controls the material falling impact force to prevent the deformation of the poured structure.

[0021] 4. By real-time detection of inventory and dynamic adjustment of replenishment timing combined with stroke displacement, the automatic coordination of replenishment operation and printing process is realized, effectively solving the technical defects of insufficient or excessive replenishment. The application can automatically maintain the material inventory in the reinforcement positioning hole of the containing cavity within a reasonable range during printing, avoiding printing interruption or uneven protective layer thickness caused by insufficient replenishment, while reducing the frequency of manual intervention and improving the continuous operation stability of construction waste recycled aggregates in 3D printing applications.

[0022] 5. The scheme combines the reinforcement positioning hole of the liftable ring-shaped jet frame with the steam curing technology, realizing the immediate automatic curing of the printed layer after forming. The steam jet angle and flow are controllable, effectively improving the curing uniformity and efficiency. The application realizes the synchronization of printing structure and curing process, solves the problem of concrete cracking caused by curing lag in traditional 3D printing, and the circumferential uniform steam distribution of the ring-shaped jet frame reinforcement positioning hole avoids the blind area in manual curing. The electric control valve accurately adjusts the steam parameters to adapt to the curing needs of different material ratios, the overall structure is compact and highly integrated with the printing equipment, significantly improving the forming quality and construction efficiency of building components.

[0023] 6. The scheme is designed by a split drive mechanism, so that the lifting action of the annular frame body steel bar positioning hole and the jet frame steel bar positioning hole is completely decoupled, avoiding the mutual interference between the printing operation and the maintenance operation, and eliminating the unstable problem of the equipment structure caused by synchronous lifting. The independent height control of the printing frame and the maintenance frame is realized, ensuring that the material replenishment and steam maintenance can be operated in parallel during the printing process. The precise positioning of the annular frame body steel bar positioning hole in the vertical direction ensures the precision of the continuous stacking of the protective layer, and the independent lifting of the jet frame steel bar positioning hole enables timely maintenance of any height layer that has completed printing, effectively solving the problem of maintenance lag affecting the strength of concrete in traditional equipment. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a structural schematic diagram of the embodiment of the present application; Figure 2 is a structural schematic diagram of the jet frame in the embodiment of the present application; Figure 3 is a structural schematic diagram of the annular frame body in the embodiment of the present application; Figure 4 is a structural schematic diagram of the annular frame body in the embodiment of the present application; Figure 5 is a structural schematic diagram of the printing assembly in the embodiment of the present application.

[0025] The drawings described herein are used to provide further understanding of the present application, and form a part of the present application. The illustrative embodiments of the present application and their descriptions serve to explain the present application, and do not constitute an improper limitation on the present application.

[0026] In the drawings: 1, lifting guide rail; 11, reinforcing cross beam; 2, annular frame body; 21, annular groove; 211, cover plate; 22, material replenishing pipe; 3, annular slide rail; 31, material discharging port; 4, sliding part; 41, accommodating cavity; 42, material discharging pipe; 43, telescopic pipe; 44, first telescopic cylinder; 45, second telescopic cylinder; 46, material outlet; 5, jet frame; 51, second guide slide; 52, gas guide pipe; 6, vertical steel bar limiting plate; 61, steel bar positioning hole. DETAILED DESCRIPTION

[0027] In order to more clearly explain the overall concept of the present application, the following will be described in detail with reference to the drawings.

[0028] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, however, the present application can also be implemented in other ways different from those described herein, therefore, the protection scope of the present application is not limited by the specific embodiments disclosed below.

[0029] In addition, in the description of the present invention, it should be understood that the terms "top", "bottom", "inside", "outside", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0030] In the present invention, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0031] In the present invention, unless otherwise clearly specified and limited, a first feature "above" or "below" a second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "implementation method", "embodiment", "one embodiment", "example" or "specific example" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0032] Reference Figures 1 to 3, a 3D printing device based on recycled aggregate from construction waste, including a vertical lifting mechanism, a accommodating area for accommodating a steel mesh in the middle of the vertical lifting mechanism, a ring frame body 2 is slidably connected to the vertical lifting mechanism, a ring storage mechanism is provided above the ring frame body 2, a ring slide rail 3 is provided below the ring frame body 2, a printing component is slidably connected to the ring slide rail 3, a plurality of discharge ports 31 are provided at the bottom of the storage mechanism, and a solenoid valve is provided on the discharge port 31. The plurality of discharge ports 31 pass through the annular slide rail 3 and are arranged at equal intervals along the annular slide rail 3. When the printing component slides to the discharge port 31, the solenoid valve is opened to replenish material for the printing component, and the output end of the printing component can be retracted to have a first position outside the steel mesh and a second position inside the steel mesh; it also includes a control system, which controls the opening or closing of the solenoid valve to realize automatic material replenishment of the printing component, and the control system controls the output end of the printing component to automatically switch between the first position and the second position.

[0033] Among them, the vertical lifting mechanism is a supporting structure with a lifting function, which can be specifically implemented by a combination of a guide rail and a drive motor, and is used to support the annular frame body 2 and realize printing height adjustment. The annular frame body 2 can be specifically formed by welding a steel structure to support the storage mechanism and the slide rail system. The annular slide rail 3 is an annular track arranged under the frame body, and can specifically adopt an aluminum alloy track structure with rollers to guide the circumferential movement of the printing component. The retractable setting of the output end of the printing component refers to a discharge device with a position adjustment function, which can specifically adopt a telescopic tube 43 structure driven by a cylinder to realize the position switching of the discharge port 31 inside and outside the steel mesh.

[0034] During operation, the rebar mesh is fixed in the middle of the vertical lift mechanism, and the annular frame body 2 rises and falls along guide rails to adjust the printing height. As the printing assembly moves along the annular guide rails 3, the solenoid valve at the discharge port 31 activates according to position signals to replenish material, ensuring a continuous supply of materials. When printing the outer protective layer of the rebar, the output port retracts to the first position to stack the outer layer. Once the set height is reached, the output port extends to the second position to insert the inner rebar mesh for filling. The control system coordinates the movement of the lift mechanism with the position switching of the printing assembly to achieve continuous layered printing.

[0035] Traditional 3D printing equipment struggles to efficiently integrate steel mesh with printed materials, and the material replenishment process relies on manual operation, resulting in low efficiency. This application utilizes a vertical lift mechanism with a built-in storage area to provide a stable installation space for the steel mesh. The annular material storage mechanism, combined with the annular slide rail and printing assembly, enables automatic material replenishment. The use of a control system allows for automated operation of the equipment, effectively resolving these issues.

[0036] Through the above technical solution, this application achieves precise matching of steel mesh positioning and printing path, ensuring the uniformity and integrity of the concrete cover. The automatic refill system eliminates the risk of printing interruptions, seamlessly integrating the outer protective layer printing with the internal filling process. The dual-position working mode of the retractable printing component effectively solves the problem of simultaneous forming of the inner and outer layers of reinforced structures, improving structural integrity and construction efficiency.

[0037] As a preferred embodiment of this application, refer to Figure 1-Figure 5 The printing component is initially in the first position and slides circumferentially along the annular slide rail 3 to print a protective layer on the outside of the steel mesh. When the height of the protective layer reaches a threshold, the printing component switches from the first position to the second position to pour material into the inside of the steel mesh.

[0038] In its initial operating state, the print head of the printing assembly is located outside the steel mesh. This can be achieved by setting the initial coordinate position of the print head, thereby ensuring the accuracy of the starting position of the protective layer printing. Circumferential sliding of the annular slide rail 3 refers to the circular motion of the printing assembly along the annular track. This can be achieved by using a servo motor to drive the rollers to engage with the track to ensure the continuity and stability of the printing path. The protective layer height threshold refers to the pre-set critical value of the protective layer stacking height. Specifically, the height data can be monitored in real time by a displacement sensor, a visual recognition system, or a height sensor. When the set value is reached, a position switching instruction is triggered.

[0039] The printing assembly is initially in the first position. Under the control system's instructions, it slides circumferentially along the annular slide rail 3 at a speed of 0.5 m / s, while simultaneously extruding material through the discharge pipe 42, printing a protective layer on the outside of the steel mesh layer by layer. During the printing process, a height sensor mounted on the vertical lifting mechanism monitors the printing height of the protective layer in real time. When the height of the protective layer reaches a preset threshold, the control system sends a signal to the printing assembly's telescopic cylinder, causing the printing assembly output end to switch from the first position to the second position. At this point, the telescopic tube 43 extends into the interior of the steel mesh and begins pouring material into it. Based on the overall architecture of the equipment, the height sensor is used to provide real-time feedback on the height of the protective layer. The control system controls the position switching of the printing assembly output end according to the preset threshold, thereby achieving an orderly printing process in which the protective layer is printed first and the interior is poured later.

[0040] In the initial stage, the printing assembly moves circumferentially along the annular slide 3. Material is discharged from the discharge port 31 and gradually accumulates on the outer side of the steel mesh to form a protective layer. When the displacement sensor detects that the height of the protective layer has reached a preset value, the control system sends a command to the first telescopic cylinder 44, driving the discharge tube 42 to flip inward. Simultaneously, the second telescopic cylinder 45 pushes the telescopic tube 43 downward, allowing the material outlet 46 to enter the interior of the steel mesh. At this time, the printing assembly continues to move along the slide, and the material is poured into the interior space of the steel mesh, achieving simultaneous formation of the inner and outer layers. During this process, the annular frame body 2 rises synchronously with the increase in printing height, ensuring that the printing assembly remains within the effective operating range.

[0041] This solution triggers an automatic switching mechanism through a preset height threshold, allowing the printing component to complete the printing of the outer protective layer and the pouring of the internal material in a single cycle, avoiding errors caused by multiple positioning, and at the same time ensuring the uniformity of the protective layer thickness through a closed-loop control system. Continuous automated printing of the inner and outer layers of the steel mesh is achieved, solving the problem of insufficient bonding strength caused by the layered pouring of the protective layer and the internal structure in traditional processes. The position switching mechanism triggered by the height threshold ensures that the protective layer immediately enters the internal pouring stage after reaching the designed thickness, avoiding material waste or structural defects caused by manual judgment errors. In addition, the coordinated control of circumferential sliding and position switching significantly improves the forming efficiency of complex steel structures, and is particularly suitable for the batch construction of large-diameter concrete columns.

[0042] As a specific embodiment of the printing component in this application, refer to Figure 3-Figure 5 The printing assembly includes a sliding portion 4 that slides with the annular slide rail 3. The upper end of the sliding portion 4 is provided with a accommodating cavity 41 for accommodating materials. The lower end of the sliding portion 4 is rotatably connected to a discharge pipe 42. The side wall of the sliding portion 4 is rotatably connected to a first telescopic cylinder 44. The telescopic end of the first telescopic cylinder 44 is rotatably connected to the discharge pipe 42. The lower end of the discharge pipe 42 is slidably connected to a telescopic tube 43. A second telescopic cylinder 45 is provided between the telescopic tube 43 and the discharge pipe 42. The lower end of the telescopic tube 43 is provided with a material outlet 46.

[0043] The sliding portion 4 is a hollow rectangular parallelepiped structure. The upper end of the accommodating chamber 41 is used to store materials. A material sensor is installed inside the accommodating chamber 41 to monitor the weight of the materials inside in real time. The lower end of the sliding portion 4 is rotatably connected to the discharge pipe 42 via a rotary bearing, allowing the discharge pipe 42 to rotate freely within a certain angle range. A first telescopic cylinder 44 is mounted on the side wall of the sliding portion 4. Its telescopic end is rotatably connected to the middle of the discharge pipe 42 via a hinge. The telescopic movement of the first telescopic cylinder 44 can drive the discharge pipe 42 to rotate around the rotary bearing to adjust the discharge direction. The telescopic tube 43 is slidably connected to the lower end of the discharge pipe 42, with a second telescopic cylinder 45 installed between the two. The telescopic movement of the second telescopic cylinder 45 can control the extension length of the telescopic tube 43, thereby enabling the output end of the printing component to switch between the first position and the second position. The material outlet 46 at the lower end of the telescopic tube 43 adopts a conical design to effectively control the extrusion speed and shape of the material.

[0044] When the sliding part 4 moves along the annular slide rail 3, the material in the accommodating chamber 41 enters the discharge pipe 42 due to gravity. When the discharge direction needs to be adjusted, the first telescopic cylinder 44 pushes the discharge pipe 42 to rotate around the hinge point so that the material outlet 46 is aligned with the outer or inner area of ​​the steel mesh. The second telescopic cylinder 45 drives the telescopic tube 43 to extend downward so that the material outlet 46 reaches a predetermined height position. During the protective layer printing stage, the discharge pipe 42 maintains an outward tilt angle, the telescopic tube 43 is in a fully retracted state, and the material is discharged evenly along the outer side of the steel mesh. When the internal structure needs to be cast, the first telescopic cylinder 44 contracts to rotate the discharge pipe 42 inward, and at the same time, the second telescopic cylinder 45 pushes the telescopic tube 43 to extend downward, and the material outlet 46 penetrates into the interior of the steel mesh for casting.

[0045] This solution achieves dual adjustment of discharge direction and height by rotating the discharge tube 42 and telescopic tube 43, solving the technical challenge of simultaneous casting of the inner and outer parts of the steel mesh. This application achieves precise positioning and casting of the printed components within the inner and outer spaces of the steel mesh, ensuring the continuous formation of the protective layer and internal structure. The height-adjustable material outlet 46 avoids blockage caused by variations in the print layer height. The rotary adjustment mechanism improves adaptability to steel meshes of varying diameters. The nested telescopic tube 43 structure effectively controls the impact of falling materials, preventing deformation of the cast structure.

[0046] Preferably, a material sensor for detecting the weight of the internal material is provided in the accommodating chamber 41. Assume that the displacement of the material in the sliding stroke of the sliding part 4 between two adjacent discharge ports 31 is N, and the material sensor detects that the material inventory in the accommodating chamber 41 is M. The maximum material capacity of the accommodating chamber 41 is 4-5N. When M=N, the accommodating chamber 41 moves to the next discharge port 31 for material replenishment.

[0047] The material discharge N is determined by testing and calculating the material discharge of the printing assembly during the sliding stroke between two adjacent discharge ports 31. The maximum capacity of the containing cavity 41 is set to 4.5N, i.e. 22.5 kg. The material sensor uses a high-precision weighing sensor to monitor the material inventory M in the containing cavity 41 in real time. When M decreases to N, the control system controls the sliding part 4 to move directly below the next discharge port 31, opens the electromagnetic valve for material replenishment, and closes the electromagnetic valve when the replenishment amount reaches 90% of the maximum capacity. During the movement of the sliding part 4 along the annular slide rail 3 to perform the printing operation, the material sensor continuously monitors the real-time inventory in the containing cavity 41. When the inventory is detected to decrease to the single stroke discharge, the control system immediately drives the sliding part 4 to move to the position of the nearest discharge port 31 and opens the electromagnetic valve for replenishment. Since the maximum capacity of the containing cavity 41 is set to 4 to 5 times the single stroke discharge, it can not only avoid frequent replenishment causing printing interruption, but also prevent excessive replenishment causing cavity blockage or material hardening. After the replenishment is completed, the sliding part 4 continues to perform the printing operation of the subsequent stroke to form a continuous printing-replenishment cycle.

[0048] The present scheme dynamically adjusts the replenishment time by real-time detection of the inventory and combination of the stroke discharge, realizes the automatic cooperation of the replenishment operation and the printing process, and effectively solves the technical defects of insufficient or excessive replenishment. The present application can automatically maintain the material inventory in the containing cavity 41 within a reasonable range during printing, avoid printing interruption or uneven protective layer thickness caused by insufficient replenishment, reduce the frequency of manual intervention, and improve the continuous operation stability of construction waste recycled aggregate in 3D printing applications.

[0049] As another preferred embodiment of the present application, with reference to Figure 1-Figure 2 The jet frame 5 is slidably connected with the vertical lifting mechanism, located below the annular frame body 2, used for curing and solidifying the protective layer printed by the printing assembly. The jet frame 5 has an airflow cavity inside, the inner side wall of the jet frame 5 is provided with a jet hole, and the outer side wall of the jet frame 5 is provided with a gas conduit 52 connected with the output end of the external curing steam supply device, and the gas conduit 52 is provided with an electric control valve.

[0050] The jet frame 5 is an annular structure installed on the vertical lifting mechanism by a sliding connection. Specifically, it can be implemented by a combination of an aluminum alloy frame and a guide rail slider. Its annular shape matches the printing path and can rise and fall synchronously with the printing height. The airflow cavity refers to a closed channel structure arranged inside the jet frame 5. Specifically, it can be implemented by a hollow annular cavity. It is used to evenly distribute the maintenance gas and maintain stable airflow pressure. The jet hole refers to the air outlet hole distributed circumferentially along the inner wall of the jet frame 5. Specifically, it can be implemented by an array of circular holes with a diameter of 2-5 mm. The direction of the hole axis is set to be inclined 30-45 degrees to the surface of the protective layer to ensure that the steam evenly covers the surface of the printed layer. The gas duct 52 refers to a pipeline assembly connecting the external steam generating equipment and the airflow cavity. The electric control valve refers to an electromagnetic regulating valve installed on the gas duct 52. Specifically, it can be implemented by a proportional electromagnetic valve. The steam flow and pressure are controlled by adjusting the opening.

[0051] Once the printing assembly completes the protective layer buildup, the control system drives the jet frame 5 to rise synchronously along the vertical lifting mechanism to the current print layer height. Curing steam from an external steam supply is injected into the airflow cavity through the gas conduit 52 and evenly sprayed onto the protective layer surface through the jet holes. An electronically controlled valve adjusts the steam output according to preset curing parameters. The annular structure of the jet frame 5 ensures that steam covers the concrete surface from all directions, preventing localized drying or over-wetting. Vertically, the jet frame 5 rises layer by layer as the print height increases, achieving dynamic and continuous curing.

[0052] This solution combines a liftable annular jet frame 5 with steam curing technology to achieve immediate, automatic curing of the printed layer after it is formed. The steam injection angle and flow rate are controllable, effectively improving curing uniformity and efficiency. This application achieves the simultaneous printing of the structure and curing process, solving the problem of concrete cracking caused by delayed curing in traditional 3D printing. The circumferentially uniform steam distribution of the annular jet frame 5 avoids the blind spots of manual curing. The electronically controlled valve precisely adjusts the steam parameters to meet the curing requirements of different material ratios. The overall structure is compact and highly integrated with the printing equipment, significantly improving the quality of building component molding and construction efficiency.

[0053] As a preferred embodiment of the vertical lifting assembly, refer to Figure 1 The vertical lifting assembly includes a lifting guide rail 1, a first guide slide is provided on the side wall of the annular frame body 2 and slides with the lifting guide rail 1, and a second guide slide 51 is provided on the side wall of the jet frame 5 and slides with the lifting guide rail 1. The lifting guide rail 1 is provided with a driving mechanism for driving the annular frame body 2 and the jet frame 5 to rise and fall along the lifting guide rail 1 respectively.

[0054] The lifting guide rail 1 is a vertical support structure that supports the annular frame body 2 and the jet frame 5. Specifically, it can be made of I-beams or H-beams, and its surface is provided with grooves or guide strips to achieve sliding fit. The first guide slide 51 and the second guide slide 51 refer to the sliding parts 4 installed on the side walls of the annular frame body 2 and the jet frame 5, respectively. Specifically, they can adopt a slider or roller structure, and achieve stable sliding by being embedded in the groove of the lifting guide rail 1. The drive mechanism refers to a power device that independently controls the lifting and lowering of the annular frame body 2 and the jet frame 5. Specifically, it can adopt a servo motor with a gear rack transmission system or a hydraulic cylinder drive to achieve independent lifting control of the two frames.

[0055] The lifting rail 1 serves as the core vertical support structure, forming a sliding connection with the annular frame body 2 and the jet frame 5 via first and second guide slides 51, respectively. The drive mechanism independently controls the lifting and lowering of the two frames, allowing the annular frame body 2 to rise synchronously with the height of the protective layer during printing, while the jet frame 5 independently adjusts its height based on maintenance requirements. For example, after the annular frame body 2 prints a protective layer, the drive mechanism raises it to the next printing height. The jet frame 5 then remains at its original height to steam-cure the printed layer. Once this curing is complete, the drive mechanism raises it to the next operating position.

[0056] This solution completely decouples the lifting and lowering actions of the annular frame body 2 and the jet frame 5 through the design of a split drive mechanism, avoiding mutual interference between the printing operation and the curing operation, and eliminating the problem of unstable equipment structure caused by synchronous lifting. The present application realizes independent height control of the printing frame and the curing frame, ensuring that material replenishment and steam curing can be operated in parallel during the printing process. The precise vertical positioning of the annular frame body 2 ensures the accuracy of the continuous stacking of the protective layer, and the independent lifting of the jet frame 5 enables it to perform timely curing of any height layer that has been completed, effectively solving the problem of delayed curing affecting the strength of concrete in traditional equipment.

[0057] As a preferred example of an annular storage mechanism, refer to Figure 1 、 Figure 3 and Figure 4The annular storage mechanism includes an annular groove 21, a feeding pipe 22 is provided on the side wall of the annular groove 21, and a cover plate 211 is detachably connected to the top of the annular groove 21. The annular groove 21 is arranged along the annular frame body 2 to form a closed-loop storage space, and the construction waste recycled aggregate mixture is continuously injected into the annular groove 21 through the side wall feeding pipe 22. When the printing component moves along the annular slide rail 3, the material in the annular groove 21 is accurately supplied to the printing component through the bottom discharge port 31. The cover plate 211 is fixed to the top of the annular groove 21 by bolts. When it is necessary to clean the residual material in the groove or switch to different proportions of aggregates, the cover plate 211 can be quickly removed for manual operation. The closed-loop structure design of the annular groove 21 increases the storage capacity by about 3 times, and the side feeding method of the feeding pipe 22 effectively avoids the risk of blockage caused by material accumulation.

[0058] This solution achieves spatial coupling between the storage space and the printing path through the coordinated design of the annular groove 21 and the annular slide rail 3. The side feeding method of the feeding tube 22 is more conducive to maintaining material uniformity than top feeding. The design of the removable cover 211 breaks through the limitations of the maintenance difficulties of traditional closed silos. Compared with the welded fixed top cover, the maintenance efficiency is improved by about 60%. At the same time, it realizes the continuous and stable supply of recycled aggregates from construction waste. The annular groove 21 structure ensures the dynamic balance between material supply and consumption during the printing process. The side feeding of the feeding tube 22 effectively maintains the stability of the material ratio. The design of the removable cover 211 significantly improves the convenience of equipment maintenance and avoids printing quality defects caused by material residue.

[0059] In addition, the upper end of the lifting guide rail 1 is slidably connected to a vertical steel bar limiting plate 6, and a number of steel bar positioning holes 61 are provided on the vertical steel bar limiting plate 6. The lifting guide rail 1 is fixedly connected with a number of reinforcing beams 11 at vertical intervals. The vertical steel bar limiting plate 6 is installed on the top of the lifting guide rail 1 by a sliding connection, and its height position can be adjusted according to the layout of the steel mesh before construction. The steel bar positioning holes 61 are arranged in an array, for example, the spacing between each column of holes is 50-100 mm, which is used to insert and fix the ends of the steel bars. The reinforcing beams 11 are set in a group at intervals of 1-2 meters along the length of the guide rail, for example, I-beams or channel steels are welded to the side walls of the guide rail to form a multi-point support structure. During the printing process, after the steel mesh is fixed through the positioning holes, the lifting guide rail 1 drives the vertical steel bar limiting plate 6 to rise synchronously to ensure that the steel mesh matches the height of the printed layer, while the reinforcing beams 11 maintain the vertical stability of the guide rail.

[0060] The scheme realizes the rapid positioning and vertical synchronous lifting of the reinforcement mesh through the cooperation of the vertical reinforcement limiting plate 6 and the positioning hole, solves the problem of mispositioning of the reinforcement and the printing layer. In addition, the existing equipment lacks reinforcing structure, and the lifting guide rail 1 is easy to bend and deform under long-time high-load working conditions. The reinforcing cross beam 11 arranged at intervals significantly improves the bending resistance of the guide rail, realizes the precise positioning of the reinforcement mesh in the vertical direction, avoids the errors caused by manual adjustment, and enhances the structural stability of the guide rail through the reinforcing cross beam 11, ensuring the vertical precision of the equipment in high-strength printing operation, and meeting the continuous construction requirements of concrete columns of different heights.

[0061] A 3D printing construction method based on construction waste recycled aggregate, specifically comprising the following steps: According to the position of the reinforcement mesh, the vertical lifting mechanism is hoisted and positioned; the concrete column size and model parameters are input to the control system, and the pouring material is poured into the annular groove 21; the control system controls the sliding part 4 to slide to the position directly below the nearest discharge port 31, and controls the electromagnetic valve of the discharge port 31 to open to pour the material into the containing cavity 41, and after the pouring is completed, the electromagnetic valve is closed; the control system controls the output end of the printing assembly to be in the first position, the sliding part 4 slides along the annular slide rail 3 in the circumferential direction and performs the material discharging and printing action, and the material is stacked and printed on the outer protective layer of the concrete column layer by layer along the outside of the reinforcement mesh, and the control system controls the annular frame body 2 to rise with the increase of the stacking height of the protective layer; the air injection frame 5 is connected with the output end of the external curing steam supply equipment through the gas conduit 52, the control system controls the electric control valve to open, and the air injection hole of the air injection frame 5 sprays the appropriate temperature steam to cure the protective layer; the sliding part 4 slides to the position directly below any discharge port 31, the control system controls the electromagnetic valve of the discharge port 31 to open, and the control system controls the output end of the printing assembly to be in the second position to pour the material into the space inside the protective layer; after the printing height reaches the preset value, the construction of a single concrete column is completed, and the vertical lifting mechanism is hoisted to the next construction area.

[0062] The vertical lifting mechanism hoisting positioning refers to adjusting the installation position of the equipment to match the spatial position of the steel mesh. Positioning can be achieved by connecting the crane hook to the lifting ring on the top of the lifting guide rail 1. The input of concrete column size parameters refers to importing the preset column height and cross-sectional size data into the control unit. The parameter transmission can be completed through the touch screen or data interface. The filling of the annular groove 21 material refers to filling the annular storage space with recycled aggregate concrete through the feeding pipe 22. A screw conveyor can be used to achieve continuous feeding. The first position of the print head refers to the end of the discharge pipe 42 extending to the outside of the steel mesh. The length of the telescopic pipe 43 is adjusted by the second telescopic cylinder 45 so that the material outlet 46 maintains a set distance from the outer surface of the steel bar. Jet curing refers to the introduction of steam of suitable temperature into the cavity of the jet frame 5 through the gas duct 52. The steam pressure can be controlled within the range of 0.2-0.5MPa, and the jet hole diameter can be set to 2-3mm.

[0063] Specifically, during the positioning stage, a laser rangefinder is used to detect the relative position of the equipment and the steel mesh, and the positioning calibration program is triggered when the deviation exceeds 5mm. During the material replenishment process, the control system calculates the optimal material replenishment path based on the real-time position of the sliding part 4, and automatically plans to move to the nearest discharge port 31 when it detects that the material inventory in the accommodating chamber 41 is lower than the set threshold. During the printing protective layer stage, the annular frame body 2 is driven by a servo motor to synchronously rise along the lifting guide rail 1 at a speed of 0.5-2cm / min to ensure a uniform thickness of the printed layer. During steam curing, the control system dynamically adjusts the steam injection volume according to the ambient temperature and humidity, and automatically stops the injection when the concrete surface temperature reaches 60°C. During the internal pouring stage, the discharge pipe 42 is driven by the first telescopic cylinder 44 to rotate 90 degrees so that the material outlet 46 is aligned with the internal space of the steel mesh.

[0064] In some specific embodiments, a visual positioning system can be installed on the top of the lifting guide rail 1, using a CCD camera to capture the coordinates of the steel mesh's characteristic points, achieving millimeter-level positioning accuracy. A two-level warning mechanism can be implemented for material replenishment: when the remaining volume in the holding chamber 41 falls below 30%, the preparatory replenishment process is initiated; when it falls below 10%, printing is paused and replenishment is prioritized. The jet curing frame can be configured with multiple independent temperature control modules to implement differentiated curing strategies for different areas.

[0065] This method utilizes a reversible printing assembly on the annular slide 3, enabling continuous printing of the protective layer and pouring of the core, avoiding process interruptions. Compared to conventional curing methods, which require the delayed application of a curing film, the integrated jetting frame 5 allows for immediate steam curing after printing, effectively shortening the concrete strength development cycle.

[0066] Through the above technical solution, this application realizes the precise application of recycled aggregates from construction waste in 3D printing, and solves the technical problem of loose bonding between steel mesh and printing materials. Through the synergistic effect of the automatic feeding mechanism and position switching control, the synchronous forming of the concrete cover and the internal structure is ensured, thereby improving the integrity of the structure. The intervention of the real-time maintenance system effectively controls the progress of the concrete hydration reaction and avoids the occurrence of surface cracking defects. The automated control of the entire construction process reduces the manual intervention link and shortens the construction period of a single concrete column by approximately 40%.

[0067] In the above method, a jet time threshold is set. When the threshold is reached, the control system controls the jet frame 5 to rise and perform jet curing on the upper protective layer. When the protective layer is printed to the set height, the jet frame 5 starts steam jetting, and the control system starts to accumulate the jet time. When the jet time reaches the preset threshold, it indicates that the basic curing of the current height protective layer has been completed, and the control system immediately triggers the lifting mechanism to drive the jet frame 5 to rise to a new working height. During this process, the rising stroke of the jet frame 5 is synchronized with the vertical displacement of the printing component, so that the steam jet always acts on the surface of the newly formed protective layer. This technical means avoids the hysteresis that may be caused by manual adjustment of the position of the jet frame 5 through the dual control of the time threshold and position linkage, while ensuring that protective layers of different heights can obtain uniform curing conditions.

[0068] This solution uses the coordinated control of time thresholds and automatic lifting to ensure that steam curing strictly matches the height changes of the printed layer. This not only avoids the waste of curing resources but also eliminates quality problems caused by untimely curing. It realizes the automated connection between the concrete cover curing operation and the 3D printing process, ensuring that each printed layer receives targeted steam curing during the critical curing period, effectively preventing shrinkage and cracking caused by rapid evaporation of moisture on the concrete surface, and improving the overall structural uniformity of the concrete column through layered progressive curing.

[0069] Anything not described in the present invention can be achieved by adopting or drawing on existing technologies.

[0070] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

[0071] The foregoing is merely an embodiment of the present invention and is not intended to limit the present invention. It will be apparent to those skilled in the art that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of the claims of the present invention.

Claims

1. A 3D printing device based on recycled aggregates from construction waste, characterized in that: The invention comprises a vertical lifting mechanism, wherein the middle portion of the vertical lifting mechanism has a storage area for accommodating a steel mesh, the vertical lifting mechanism is slidably connected to an annular frame body (2), an annular material storage mechanism is provided above the annular frame body (2), an annular slide rail (3) is provided below the annular frame body (2), a printing assembly is slidably connected to the annular slide rail (3), a plurality of discharge ports (31) are provided at the bottom of the storage mechanism, an electromagnetic valve is provided on the discharge port (31), the plurality of discharge ports (31) pass through the annular slide rail (3) and are arranged at equal intervals along the annular slide rail (3), when the printing assembly slides to the discharge port (31), the electromagnetic valve is opened to replenish material for the printing assembly, and the output end of the printing assembly can be telescopically arranged so that it has a first position located outside the steel mesh and a second position located inside the steel mesh; It also includes a control system, which controls the opening or closing of the electromagnetic valve to achieve automatic material replenishment of the printing component, and the control system controls the output end of the printing component to automatically switch between a first position and a second position.

2. A 3D printing device based on recycled aggregates from construction waste according to claim 1, characterized in that: The printing component is initially in a first position and slides circumferentially along the annular slide rail (3) to print a protective layer on the outside of the steel mesh. When the height of the protective layer reaches a threshold, the printing component switches from the first position to a second position to pour material into the interior of the steel mesh.

3. The 3D printing device based on recycled aggregates from construction waste according to claim 2, characterized in that: The printing assembly comprises a sliding portion (4) that is slidably engaged with the annular slide rail (3); a holding cavity (41) for holding materials is provided at the upper end of the sliding portion (4); a discharge pipe (42) is rotatably connected to the lower end of the sliding portion (4); a first telescopic cylinder (44) is rotatably connected to the side wall of the sliding portion (4); the telescopic end of the first telescopic cylinder (44) is rotatably connected to the discharge pipe (42); a telescopic tube (43) is slidably connected to the lower end of the discharge pipe (42); a second telescopic cylinder (45) is provided between the telescopic tube (43) and the discharge pipe (42); and a material outlet (46) is provided at the lower end of the telescopic tube (43).

4. The 3D printing device based on recycled aggregates from construction waste according to claim 3, characterized in that: A material sensor for detecting the weight of the material inside is provided in the accommodating chamber (41). Assuming that the displacement of the material in the sliding stroke of the sliding portion (4) between two adjacent discharge ports (31) is N, the material sensor detects that the material inventory in the accommodating chamber (41) is M. The maximum material capacity of the accommodating chamber (41) is 4-5N. When M=N, the accommodating chamber (41) moves to the next discharge port (31) for material replenishment.

5. The 3D printing device based on recycled aggregates from construction waste according to claim 3, characterized in that: The invention also includes an air jet frame (5) slidably connected to the vertical lifting mechanism, the air jet frame (5) is located below the annular frame body (2), and is used to maintain and solidify the protective layer printed by the printing component. The air jet frame (5) has an air flow cavity inside, and the inner wall of the air jet frame (5) is provided with an air jet hole. The outer wall of the air jet frame (5) is provided with a gas conduit (52) for connecting to the output end of an external maintenance steam supply device, and the gas conduit (52) is provided with an electric control valve.

6. The 3D printing device based on recycled aggregates from construction waste according to claim 5, characterized in that: The vertical lifting assembly includes a lifting guide rail (1), a first guide slide member that is slidably matched with the lifting guide rail (1) is provided on the side wall of the annular frame body (2), a second guide slide member (51) that is slidably matched with the lifting guide rail (1) is provided on the side wall of the jet frame (5), and a driving mechanism is provided on the lifting guide rail (1) for respectively driving the annular frame body (2) and the jet frame (5) to rise and fall along the lifting guide rail (1).

7. The 3D printing device based on recycled aggregates from construction waste according to claim 2, characterized in that: The annular material storage mechanism comprises an annular groove (21), a feeding pipe (22) is provided on the side wall of the annular groove (21), and a cover plate (211) is detachably connected to the top of the annular groove (21).

8. The 3D printing device based on recycled aggregates from construction waste according to claim 1, characterized in that: The upper end of the lifting guide rail (1) is slidably connected to a vertical steel bar limiting plate (6), and the vertical steel bar limiting plate (6) is provided with a plurality of steel bar positioning holes (61). The lifting guide rail (1) is fixedly connected to a plurality of reinforcing beams (11) at vertical intervals.

9. A 3D printing construction method based on recycled aggregates from construction waste, characterized in that: The specific steps include: S1. Hoist and position the vertical lifting mechanism according to the position of the steel mesh; S2, inputting the size and model parameters of the concrete column into the control system, and filling the casting material into the annular groove (21); S3, the control system controls the sliding part (4) to slide to the position directly below the nearest discharge port (31), and controls the electromagnetic valve of the discharge port (31) to open to fill the accommodating chamber (41) with materials, and the electromagnetic valve closes after the filling is completed; S4, the control system controls the output end of the printing component to be in the first position, the sliding part (4) slides circumferentially along the annular slide rail (3) and performs the material placement and printing action, stacking the material layer by layer along the outside of the steel mesh to print the outer protective layer of the concrete column, and the control system controls the annular frame body (2) to rise as the height of the protective layer stacking increases; S5, the jet frame (5) is connected to the output end of the external curing steam supply equipment through the gas conduit (52), the control system controls the electric control valve to open, and the jet holes of the jet frame (5) spray steam of suitable temperature to cure the protective layer; S6, the sliding part (4) slides directly below any discharge port (31), the control system controls the solenoid valve of the discharge port (31) to open, and the control system controls the output end of the printing component to be in the second position, so as to pour the material into the inner space of the protective layer; S7. After the printing height reaches the preset value, the construction of a single concrete column is completed, and the vertical lifting mechanism is hoisted to the next construction area.

10. A 3D printing construction method based on recycled aggregates from construction waste according to claim 9, characterized in that: In step S5, a jet time threshold is set. When the threshold is reached, the control system controls the jet frame (5) to rise to perform jet curing on the upper protective layer.

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