3D printing concrete interface reinforcing method and system

Abstract

The invention discloses a 3D printing concrete interface reinforcing method and system, and relates to the technical field of 3D printing concrete.The 3D printing concrete interface reinforcing method comprises the following steps that the nth layer of concrete is printed, and n is an integer; placing a vibrating piece on the upper surface of the nth layer of concrete; and the (n + 1) th layer of concrete is printed on the upper surface of the nth layer of concrete, the vibration piece vibrates at the interface, and the concrete at the interface of the nth layer of concrete and the (n + 1) th layer of concrete is fluidized and can be in contact fusion after the vibration piece is removed. According to the 3D printing concrete interface reinforcing method and system, the connecting performance of the concrete interface can be improved, and then the overall performance of the structure is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing concrete, and particularly to a method and system for strengthening the interface of 3D printed concrete. Background Art

[0002] As a new building manufacturing method, 3D printing concrete technology has the advantage of precise dosage control, can effectively save the amount of concrete used, reduce carbon emissions caused by the production of concrete raw materials, bring good economic benefits to the construction industry, and also bring certain improvements to the ecological environment. However, 3D printing concrete technology forms a three-dimensional structure by composing each layer with strips of materials one by one, and then combining layers of surfaces. This manufacturing method results in a large number of interfaces between lines and between layers in the structure.

[0003] These interfaces are weakening areas of mechanical strength. At the same time, due to the lack of reinforcement by traditional steel bars, the mechanical properties of 3D printed concrete structures far from meet the requirements of engineering applications. Especially when printing large-sized structures, at the same horizontal position, the printing time interval between adjacent layers is relatively long, resulting in the preliminary curing of the lower-layer concrete. When the upper-layer concrete arrives, the bond strength between the two layers is insufficient, seriously affecting the overall performance of the structure. Summary of the Invention

[0004] The purpose of the present invention is to provide a method and system for strengthening the interface of 3D printed concrete to solve the problems existing in the above-mentioned prior art, improve the connection performance of the concrete interface, and further improve the overall performance of the structure.

[0005] To achieve the above purpose, the present invention provides the following solutions: The present invention provides a method for strengthening the interface of 3D printed concrete, including the following steps: Print the nth layer of concrete, where n is an integer; Place a vibrating member on the upper surface of the nth layer of concrete; Print the (n + 1)th layer of concrete on the upper surface of the nth layer of concrete. The vibrating member vibrates at the interface, causing the concrete at the interface between the nth layer of concrete and the (n + 1)th layer of concrete to be fluidized and able to contact and fuse after removing the vibrating member.

[0006] Preferably, when printing the (n + 1)th layer of concrete on the upper surface of the nth layer of concrete, the vibrating member moves synchronously with the printing stroke of the (n + 1)th layer of concrete at the interface and vibrates, so that the concrete at the interface between the nth layer of concrete and the (n + 1)th layer of concrete is fluidized and gradually contacts and fuses with the movement of the vibrating member.

[0007] Preferably, when printing the (n + 1)th layer of concrete on the upper surface of the nth layer of concrete and the vibrating member vibrates at the interface, a strengthening material is injected synchronously at the interface.

[0008] Preferably, the vibrating member is arranged as a vibrating plate, and the evacuation end of the vibrating plate has a wavy structure.

[0009] Preferably, reinforcing bars are left at the part of the vibrating plate where the (n + 1)-th layer of concrete is not covered, and the reinforcing bars can be separated from the vibrating plate when the vibrating plate evacuates from the interface between the n-th layer of concrete and the (n + 1)-th layer of concrete and remain at the interface.

[0010] Preferably, the reinforcing bars are arranged in a wavy shape, and the vibrating process of the vibrating plate can cause the reinforcing bars to turn over and remain at the interface at an angle relative to the horizontal plane.

[0011] Preferably, a one-way fluid channel is arranged in the vibrating member, one end of the one-way fluid channel is used to communicate with a liquid injection mechanism, and the other end extends to the evacuation end of the vibrating member and communicates with the interface, and the reinforcing material can be injected to the interface through the one-way fluid channel.

[0012] Preferably, the following steps are further included: Detect the fluidization degree at the interface where the n-th layer of concrete and the (n + 1)-th layer of concrete come into contact and fuse, and it is also possible to monitor the temperature change at the interface when the vibrating member vibrates at the interface. The vibrating parameters of the vibrating member are adjusted in real time according to the fluidization degree detection information or the temperature change information.

[0013] The present invention also provides a 3D printing concrete interface reinforcement system, including a 3D printing mechanism and a vibrating mechanism; the 3D printing mechanism is used for printing concrete layer by layer; the vibrating mechanism includes a vibrating member and a vibrating driver, the vibrating member is used to be placed on the upper surface of the n-th layer of concrete, and the vibrating member can move synchronously along with the printing path of the 3D printing mechanism; the vibrating driver is connected to the vibrating member and can drive the vibrating member to vibrate.

[0014] Preferably, it further includes a liquid injection mechanism, a layout mechanism, a detection component and a control mechanism; a one-way fluid channel is arranged in the vibrating member, one end of the one-way fluid channel communicates with the liquid injection mechanism, and the other end extends to the evacuation end of the vibrating member and communicates with the interface, and the liquid injection mechanism can inject the reinforcing material to the interface through the one-way fluid channel; the layout mechanism is used for arranging the reinforcing bars on the vibrating member; the detection component is used for detecting the fluidization degree information at the interface where they come into contact and fuse and / or monitoring the temperature change information at the interface when the vibrating member vibrates at the interface; the control mechanism is communicatively connected to the detection component and is used for receiving the detected information; the control mechanism can also be communicatively connected to the vibrating driver and can adjust the vibrating parameters of the vibrating member.

[0015] The present invention has achieved the following technical effects compared with the prior art: The 3D printing concrete interface reinforcement method and system provided by the present invention arrange a vibrating member between two layers of concrete interfaces during the printing process and vibrate at a specific frequency. Under the action of vibration, the semi-solid concrete on both sides of the interface is fluidized to improve fluidity. When the vibrating member moves away, the materials on both sides can fully contact and fuse due to enhanced fluidity and gradually solidify, thereby realizing interface repair, improving the connection performance of the concrete interface, and further improving the overall performance of the printed concrete structure. Brief Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 It is a schematic structural diagram of the 3D printing concrete interface reinforcement system provided in Embodiment 2; Figure 2 It is a schematic structural diagram of the vibrating member provided in Embodiment 2; Figure 3 It is a schematic diagram of the position of the reinforcing rib in the interface provided in Embodiment 2.

[0018] In the figure: 1 - 3D printing mechanism; 11 - nozzle; 2 - vibration mechanism; 21 - vibrating member; 211 - one-way fluid channel; 22 - vibration driver; 3 - liquid injection mechanism; 4 - arrangement mechanism; 41 - reinforcing rib; 5 - detection component. Detailed Embodiments

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0020] The purpose of the present invention is to provide a 3D printing concrete interface reinforcement method and system to solve the problems existing in the above-mentioned prior art, improve the connection performance of the concrete interface, and further improve the overall performance of the structure.

[0021] To make the above-mentioned objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0022] Embodiment 1 This embodiment provides a method for strengthening the interface of 3D printed concrete, including the following steps: Print the nth layer of concrete, where n is an integer, and further, n is an integer greater than 0, representing any layer; Place the vibrating member 21 on the upper surface of the nth layer of concrete; Print the (n + 1)th layer of concrete on the upper surface of the nth layer of concrete. The vibrating member 21 vibrates at the interface, causing the concrete at the interface between the nth layer of concrete and the (n + 1)th layer of concrete to become fluidized and be able to contact and fuse after the vibrating member 21 is removed.

[0023] Among them, during the printing process, a vibrating member 21 is arranged between the interfaces of two layers of concrete, as Figure 1 shown, and vibrates at a specific frequency. Under the action of vibration, the semi-solid concrete on both sides of the interface becomes fluidized and its fluidity is improved. When the vibrating member 21 is moved and removed, the materials on both sides can fully contact and fuse due to enhanced fluidity and gradually solidify, thereby realizing interface repair, improving the connection performance of the concrete interface, and further enhancing the overall performance of the printed concrete structure.

[0024] In an alternative embodiment of this embodiment, preferably, when printing the (n + 1)th layer of concrete on the upper surface of the nth layer of concrete, the vibrating member 21 moves synchronously with the printing stroke of the (n + 1)th layer of concrete at the interface and vibrates, so that the concrete at the interface between the nth layer of concrete and the (n + 1)th layer of concrete becomes fluidized and gradually contacts and fuses with the movement of the vibrating member 21.

[0025] Among them, by making the vibrating member 21 move and vibrate synchronously with the printing stroke, timely repair of the interface is achieved, avoiding delayed vibration, which may cause difficulty in solidifying and improving fluidization at the interface.

[0026] In an alternative embodiment of this embodiment, preferably, when printing the (n + 1)th layer of concrete on the upper surface of the nth layer of concrete and the vibrating member 21 vibrates at the interface, a strengthening material is injected synchronously at the interface.

[0027] Among them, by injecting the strengthening material synchronously and being vibrated and stirred by the vibrating member 21, it is fully mixed to the interface, thereby further improving the connection performance of the interface.

[0028] Further, the strengthening material is selected from common specific strengthening materials according to different performance requirements, and may include the following selection scenarios: Suitable for the case of early strength requirement: Disperse nano-silica powder (particle size 20 - 50 nm) in deionized water to prepare a suspension with a solid content of 20 - 30%; prepare an active calcium oxide solution with a concentration of 5 - 10%; use a high-speed shear mixer to mix the above two materials in a ratio of 1:1, with a mixing speed of 2000 - 3000 rpm and a mixing time of 5 - 10 minutes; add 0.2 - 0.5% of polyacrylamide as a thickener to adjust the viscosity of the mixture to 80 - 120 mPa·s; the prepared repair material should be used up within 2 hours.

[0029] Suitable for the case of improving toughness: Mix ethylene-vinyl acetate copolymer (EVA) powder and deionized water in a weight ratio of 1:4; stir in a water bath at 60 - 70 °C for 30 - 45 minutes until completely dispersed; add 0.1 - 0.3% of non-ionic surfactant to improve the dispersibility; after cooling to room temperature, filter through a 200-mesh sieve to obtain an EVA suspension with a solid content of 15 - 25%; adjust the pH value to 7.5 - 8.5 to increase the storage stability.

[0030] Suitable for conventional conditions: Prepare a polycarboxylate superplasticizer (solid content 30 - 40%); mix sodium silicate solution (modulus 2.0 - 2.5) and calcium chloride solution (concentration 10 - 15%) in a volume ratio of 3:1 to form a precursor of calcium silicate gel; add polycarboxylate superplasticizer to 5 - 8% of the total volume under stirring; obtain a calcium silicate hydrogel with an appropriate viscosity (150 - 200 mPa·s) by controlling the reaction time (usually 30 - 60 seconds); complete the preparation 10 - 15 minutes before use.

[0031] In the alternative solutions of this embodiment, more preferably, please refer to Figure 2 , the vibrating member 21 is set as a vibrating plate, and the evacuation end of the vibrating plate has a wavy structure.

[0032] Among them, the evacuation end of the vibrating plate is defined as the end part that is finally withdrawn from the interface during the process of the vibrating plate evacuating from the interface, that is Figure 2The left end of [it]; the structure of the vibrating plate can increase the vibration area, thereby enhancing the strengthening rate of the interface. The wavy structure can increase the fluidization rate of the interface, achieve full fusion and homogenization of the fluidized region, and compared with a flat thin sheet, it can improve the interface bonding strength, the interface microstructure is denser, and the porosity is reduced. This technology is particularly suitable for structural parts with high requirements for interface strength; further, the design and manufacture of the wavy thin sheet: the vibrating plate can use computer-aided design software (CAD) to design a thin sheet model with a wavy shape. The wave parameters are: wave period: 5 - 10 mm, preferably 7 mm; wave amplitude: 1 - 3 mm, preferably 2 mm; wave shape: select sine wave, triangular wave or composite waveform; the material is selected from high-elastic alloy materials (such as manganese copper alloy, nickel-titanium alloy, etc.) to improve the fatigue life; the basic thin sheet can be formed by laser cutting or precision stamping technology, and the accuracy is controlled within ±0.05 mm; the surface of the vibrating plate can also be polished, and the surface roughness Ra ≤ 0.4 μm to reduce the adhesion of concrete; a protective coating can also be sprayed on the surface of the vibrating plate, such as a polytetrafluoroethylene (PTFE) coating with a thickness of 0.01 - 0.02 mm to improve wear resistance and anti-adhesion.

[0033] In addition, the method of finite element analysis needs to be used to determine: the natural frequency and vibration mode of the vibrating plate, and avoid the resonance frequency; for different wave shapes, determine the optimal vibration frequency range: sine waveform: preferably the frequency is 15 - 25 Hz; triangular waveform: preferably the frequency is 20 - 30 Hz; composite waveform: preferably the frequency is 10 - 20 Hz; in addition to the conventional longitudinal vibration of the vibrating plate, a transverse micro-vibration component is added (the transverse amplitude is 10 - 20% of the longitudinal amplitude), and a dynamic balance test is carried out on the vibrating plate to ensure vibration stability; during the specific vibration process, the transverse vibration of the vibrating plate forms an angle of 15 - 30 degrees with the direction of its own linear movement, which can enhance the stirring effect; among them, the matching relationship between the moving speed of the vibrating plate and the vibration frequency: moving speed (mm / s) ≈ vibration frequency (Hz) × wave period (mm) × (0.1 - 0.2). The vibrating plate can adopt a variable-frequency vibration method, and the frequency changes from low to high and then to low within one vibration cycle to enhance the fluidization uniformity and avoid [problems]; it can also dynamically adjust the vibration intensity according to different positions of the printing path: straight section: standard vibration intensity; corner area: the vibration intensity is increased by 20 - 30%; overlapping area: the vibration intensity is increased by 10 - 20%.

[0034] In the alternative solution of this embodiment, more preferably, a reinforcing bar 41 is left at the part of the vibrating plate where the (n + 1)-th layer of concrete is not covered, and the reinforcing bar 41 can be separated from the vibrating plate and left at the interface when the vibrating plate withdraws from the interface between the n-th layer of concrete and the (n + 1)-th layer of concrete.

[0035] Among them, the reinforcing rib 41 can be separated from the vibrating piece under the resistance of the interfacial concrete as the vibrating piece is withdrawn and left at the interface. By leaving the reinforcing rib 41 at the fluidized interface and embedding it into the materials on both sides of the interface, it provides a durable interfacial connection and strengthening after curing.

[0036] In an alternative embodiment of the present example, preferably, as Figure 3 shown, the reinforcing rib 41 is arranged in a wavy shape, and the vibrating process of the vibrating piece can cause the reinforcing rib 41 to flip and be left at the interface at an angle relative to the horizontal plane.

[0037] Among them, the vibrating piece can be used as a guiding device for the reinforcing rib 41 to accurately position the reinforcing rib 41 at the center of the fluidized area as much as possible; during the vibration process of the vibrating piece, as the printing progresses, these reinforcing ribs 41 will be brought into the interface; the wavy mechanism arranged at the end of the vibrating piece can flip the reinforcing rib 41 so that the reinforcing rib 41 can be placed at the interface at a certain angle with the horizontal plane to be able to connect with the concrete on both sides. It is similar to sewing the interface with the wavy reinforcing rib 41, and the sewing-type reinforcement forms a mechanical interlocking structure at the interface, significantly improving the tensile, bending and shear resistance of the interface, effectively solving the problem of the lack of steel bars in the 3D printed concrete structure; it is suitable for the reinforcement of key parts of the structure under stress and can greatly improve the overall performance of the 3D printed concrete structure.

[0038] In addition, according to the structural requirements of the concrete, the reinforcing rib 41 can be selected from one of the following three materials: stainless steel wire: 304 or 316L grade stainless steel is selected, with a diameter of 0.5 - 1.0 mm and a tensile strength ≥ 600 MPa; carbon fiber composite wire: the carbon fiber volume content is 40 - 60%, the diameter is 0.8 - 1.2 mm, and the tensile strength ≥ 1500 MPa; glass fiber reinforced plastic wire: the glass fiber content is 60 - 70%, the diameter is 0.8 - 1.5 mm, and the tensile strength ≥ 800 MPa; further, the surface of the reinforcing rib 41 can also be treated to improve the adhesiveness. For metal wires, pickling and passivation treatment can be used to improve the corrosion resistance and adhesiveness; for composite material wires: plasma treatment is carried out on the surface to increase the surface roughness and interfacial adhesiveness. The reinforcing rib 41 can be pre-bent into a wavy shape using a precision bending machine, and the wave parameters are: wave period: 15 - 25 mm, preferably 20 mm; wave height: 5 - 10 mm, preferably 7 mm; bending angle: 60 - 90 degrees, preferably 75 degrees.

[0039] In an alternative embodiment of the present example, preferably, a one-way fluid channel 211 is arranged inside the vibrating member 21. One end of the one-way fluid channel 211 is used to communicate with the liquid injection mechanism 3, and the other end extends to the withdrawal end of the vibrating member 21 and communicates with the interface, and the strengthening material can be injected into the interface through the one-way fluid channel 211.

[0040] Among them, by arranging the one-way fluid channel 211 on the vibrating member 21 for liquid injection, the strengthening material can be accurately injected into the fluidized area and fully integrated with the concrete on both sides. To form the one-way fluid channel 211, laser micro-hole processing technology can be used to process multiple micro-channel holes with a diameter of 0.1 - 0.3 mm on a vibrating plate with a thickness of 0.3 - 0.5 mm, and the hole pitch is 5 - 10 mm; the micro-channel holes are evenly distributed along the length direction of the vibrating plate and converge into a main channel at the edge of the thin plate. The diameter of the main channel is 1.0 - 1.5 mm, which is connected to an external repair material injection system. The main channel and multiple micro-channel holes form the one-way fluid channel 211, and the surface of the channel is treated with hydrophilicity to ensure that the strengthening material can flow smoothly; a one-way valve structure is designed inside the main channel or micro-channel holes to prevent the concrete from flowing back and blocking the channels.

[0041] In addition, by arranging the one-way fluid channel 211 on the vibrating member 21 for liquid injection, the coordinated operation of vibration and liquid injection can be realized: start the liquid injection mechanism 3 after 0.05 - 0.1 seconds of the start of vibration to ensure that the strengthening material is injected while the material is in a fluidized state; the liquid injection time is 0.05 seconds shorter than the vibration time to ensure that the repair material is completely injected into the fluidized area; after the liquid injection is completed, the vibration continues for 0.05 - 0.1 seconds to promote the full mixing of the strengthening material and the concrete; the liquid injection volume can be adjusted according to different concrete ratios: for standard ratio concrete, the dosage of the repair material is 3% (volume ratio) of the interface area; for high-performance concrete, the dosage of the repair material can be increased to 4 - 5%; for lightweight concrete, the dosage of the repair material should be controlled within 2 - 3%.

[0042] In an alternative solution of this embodiment, preferably, the 3D printing concrete interface reinforcement method provided in this embodiment further includes the following steps: detecting the degree of fluidization at the interface where the nth layer of concrete and the (n + 1)th layer of concrete come into contact and fuse, and being able to monitor the temperature change at the interface while the vibrating member 21 vibrates at the interface. Based on the degree of fluidization detection information or temperature change information, the vibration parameters of the vibrating member 21 are adjusted in real time.

[0043] Among them, by detecting the degree of fluidization and monitoring the temperature change information at the interface during vibration at the interface, the real-time monitoring of the fluidized state of the concrete interface can be realized, and the vibration parameters are intelligently adjusted accordingly to ensure the quality of interface repair and strengthening; the overall performance and reliability of the 3D printed concrete structure are improved.

[0044] A complete reinforcement method for the 3D printed concrete interface provided in this embodiment is as follows: Preliminary preparation: Determine the printing concrete mix ratio: For example, the water-cement ratio is 0.35 - 0.4, add 0.5 - 1.0% of polycarboxylate superplasticizer, 0.05 - 0.1% of hydroxypropyl methylcellulose (HPMC) as a viscosity regulator, and 0.5 - 2.0% of silica fume as a reinforcing material; Prepare the vibrating plate: Made of stainless steel or carbon fiber composite material with a thickness of 0.2 - 0.5 mm, the width should be 5 - 10 mm greater than the printing line width, and the length should be between 100 - 200 mm; Debug the vibration parameters of the vibrating plate: The frequency range is 5 - 60 Hz, and the adjustable amplitude range is 0.1 - 2.0 mm; Installation: Ensure that the vibrating plate maintains a relatively fixed distance (20 - 50 mm) from the nozzle 11 of the printing mechanism and can move with the nozzle 11.

[0045] Printing the nth layer of concrete: Print the nth layer of concrete along the preset path, with a line width of 15 - 30 mm and a layer height of 5 - 15 mm; Precisely control the Z-axis of the printing mechanism and lift the nozzle 11 to a position 0.2 mm above the surface of the Nth layer; Insert the vibrating plate from the front end of the printing direction so that it fits perfectly with the surface of the nth layer, and control the fitting pressure within the range of 0.01 - 0.05 MPa; Synchronously carry out the printing of the (n + 1)th layer and the vibration fluidization: The printing nozzle 11 starts to extrude the concrete material, and the initial extrusion amount is 120% of the normal value to ensure full coverage of the vibrating plate; When the (n + 1)th layer of concrete is extruded and covers the vibrating plate, immediately vibrate the vibrating plate. The initial vibration frequency is set to 15 Hz, the amplitude is 0.5 mm, and the lateral vibration component is 0.1 mm; The vibrating plate adopts an intermittent working mode: Each vibration lasts for 0.1 - 0.2 seconds, with an interval of 0.1 second, and continuously conducts 3 - 5 vibration cycles; During the vibration process, monitor the temperature change at the interface in real time. If the temperature rises by more than 2℃, it indicates that the material starts to fluidize; According to the temperature change and the material state, dynamically adjust the vibration parameters: When the temperature change is not obvious (<1℃), increase the vibration frequency by 5 Hz and / or the amplitude by 0.2 mm; When the temperature change is obvious (>3℃), decrease the vibration frequency by 5 Hz and / or the amplitude by 0.2 mm to prevent excessive fluidization.

[0046] Movement of the vibrating plate and interface fusion: After the vibration is completed, the vibrating plate moves forward with the printing nozzle 11, and the moving speed is synchronized with the printing speed (usually 10 - 50 mm / s); To ensure full contact of the fluidized area, delay for 0.1 - 0.3 seconds after the vibrating plate moves before the next vibration; The moving distance of the vibrating plate should be less than 1 / 3 of the length of the fluidized area to ensure sufficient overlap of the fluidized area; For the corner area or the place where the printing direction changes, reduce the printing speed to 50 - 70% of the normal value and increase the vibration time to 0.2 - 0.3 seconds; Use a variable-frequency vibration mode with a frequency range of 15 - 25 Hz.

[0047] Interface fluidization quality monitoring and parameter adjustment: Measure the degree of fluidization every 10 - 20 mm of movement; the feedback relationship between the degree of fluidization and the vibration parameters is as follows: when the fluidization is insufficient (vibration wave attenuation ratio R value > 0.5), increase the vibration frequency by 2 - 5 Hz or the amplitude by 0.1 - 0.2 mm in the next vibration cycle; when the fluidization is moderate (vibration wave attenuation ratio R value between 0.3 - 0.5), maintain the current vibration parameters; when the fluidization is excessive (vibration wave attenuation ratio R value < 0.3), decrease the vibration frequency by 2 - 5 Hz or the amplitude by 0.1 - 0.2 mm. For different ambient temperature conditions, preset the vibration parameter adjustment range: when the ambient temperature is 10 - 20 °C, the reference vibration frequency is set to 20 - 25 Hz; when the ambient temperature is 20 - 30 °C, the reference vibration frequency is set to 15 - 20 Hz; when the ambient temperature is 30 - 40 °C, the reference vibration frequency is set to 10 - 15 Hz.

[0048] Completion of post - treatment: After the first - layer printing is completed, uniformly cure the interface, and a micro - mist spraying device can be used to provide appropriate moisture; for key structural parts, secondary vibration strengthening can be carried out after completion, and the vibration frequency is 70 - 80% of the initial vibration; a portable ultrasonic detector can also be used to sample - detect the completed interface to confirm the interface quality.

[0049] In addition, the method provided in this embodiment sets a series of corresponding relationships between vibration parameters and time according to the time - dependent performance of concrete: when the time interval between the nth layer and the (n + 1)th layer is within 10 minutes, use a frequency of 10 - 15 Hz; when the interval is 10 - 30 minutes, use a frequency of 15 - 25 Hz; when the interval is 30 - 60 minutes, use a frequency of 25 - 40 Hz; when the interval exceeds 60 minutes, use a frequency of 40 - 60 Hz and increase the vibration duration to 0.3 - 0.5 seconds.

[0050] Embodiment 2 This embodiment provides a 3D - printed concrete interface reinforcement system, please refer to Figures 1 - 3 , which includes a 3D printing mechanism 1 and a vibration mechanism 2; the 3D printing mechanism 1 is used for layer - by - layer printing of concrete; the vibration mechanism 2 includes a vibration member 21 and a vibration driver 22. The vibration member 21 is used to be placed on the upper surface of the nth - layer concrete, and the vibration member 21 can move synchronously with the printing path of the 3D printing mechanism 1; the vibration driver 22 is connected to the vibration member 21 and can drive the vibration member 21 to vibrate.

[0051] During the printing process of the 3D printing mechanism 1, a vibration member 21 is arranged between two layers of concrete interfaces, as shown in Figure 1As shown, it vibrates at a specific frequency under the drive of the vibration driver 22. Under the action of vibration, the semi-solid concrete on both sides of the interface is fluidized to improve fluidity. When the vibrating member 21 moves away, the materials on both sides can fully contact and fuse due to enhanced fluidity and gradually solidify, thereby realizing interface repair, improving the connection performance of the concrete interface, and further enhancing the overall performance of the printed concrete structure.

[0052] Further preferably, the 3D printing concrete interface reinforcement system provided in this embodiment further includes a liquid injection mechanism 3, a placement mechanism 4, a detection component 5, and a control mechanism; a one-way fluid channel 211 is provided in the vibrating member 21. One end of the one-way fluid channel 211 communicates with the liquid injection mechanism 3, and the other end extends to the evacuation end of the vibrating member 21 and communicates with the interface. The liquid injection mechanism 3 can inject the strengthening material into the interface through the one-way fluid channel 211; the placement mechanism 4 is used to place the reinforcing bars 41 on the vibrating member 21; the detection component 5 is used to detect the fluidization degree information at the interface where contact and fusion occur and / or monitor the temperature change information at the interface when the vibrating member 21 vibrates at the interface; the control mechanism is communicatively connected to the detection component 5 for receiving the detected information; the control mechanism can also be communicatively connected to the vibration driver 22 and can adjust the vibration parameters of the vibrating member 21.

[0053] Among them, the 3D printing mechanism 1 is set as a conventional mechanism, which can be based on a 6-degree-of-freedom industrial robot or a 3-5-axis gantry mechanical structure. Positioning accuracy: ±0.5 mm, repeat positioning accuracy: ±0.1 mm; maximum working space: not less than 5 m × 5 m × 3 m; load capacity: ≥100 kg, meeting the weight requirements of the concrete extrusion and vibration equipment; the screw extrusion device of the 3D printing mechanism 1 has a rotation speed range of 0 - 120 rpm and a step adjustment accuracy of 1 rpm; the extrusion diameter control range: 15 - 30 mm, adjustable accuracy ±1 mm; extrusion pressure: 0.5 - 2.0 MPa, pressure fluctuation controlled within ±5%; flow control accuracy: ±3%, ensuring the uniformity of the printed line.

[0054] Among them, the vibration driver 22 of the vibration mechanism 2 can be a piezoelectric or electromagnetic vibrator, with a frequency response of 5 - 100 Hz; amplitude control accuracy: ±0.05 mm; it can be fixedly sleeved on the nozzle 11 of the 3D printing mechanism 1 through a bolt fixing clamp, and can move synchronously with the nozzle 11 to drive the vibration of the vibrating part 21. Among them, the liquid injection mechanism 3 can be a micro-precision injection pump, with a flow control accuracy of up to ±0.5%, and a pressure range of 0.1 - 0.5 MPa; the liquid injection mechanism 3 can be connected to the housing of the vibration driver 22 and is integrally arranged with the vibration mechanism 2 to achieve synchronous movement with the nozzle 11 and meet the liquid injection requirements; the initial flow rate is 0.1 - 0.3 ml / s, and the liquid injection pressure is 0.2 - 0.3 MPa; in addition, the liquid injection mechanism 3 is connected to the one-way fluid channel through a liquid injection pipeline, and a pressure sensor can be installed on the liquid injection pipeline to monitor the pressure change in the one-way fluid channel. When the pressure increases by more than 20%, the pressure is increased by 0.05 MPa.

[0055] Among them, the arrangement mechanism 4 is set to include a slideway, an elastic member, and an ejecting member. Among them, a plurality of reinforcing ribs 41 are arranged side by side along the length direction inside the slideway, and each reinforcing rib 41 is arranged perpendicular to the bottom wall of the slideway; and an outlet is arranged at one end of the bottom wall of the slideway, and the outlet is set to only allow a single reinforcing rib 41 to fall each time. The ejecting member is fixedly arranged on the slideway and is close to the outlet. The ejecting member ejects the reinforcing ribs 41 through the outlet in sequence. The elastic member is arranged at the other end of the slideway and presses a plurality of reinforcing ribs 41 tightly in the slideway by its own elastic supporting force; the working principle of the arrangement mechanism 4 is similar to that of a stapler; the slideway can be surrounded by a rectangular column closed or semi-closed housing and is fixedly arranged on the outer wall of the nozzle 11 by welding or through a fixing clamp. The elastic member is set as a spring, one end of the spring is fixedly connected to the slideway, and the other end presses a plurality of reinforcing ribs 41 through a pressing plate; the ejecting member is set as an electric telescopic rod, and a ejecting rod can be fixedly arranged at the front end of the electric telescopic rod. The ejecting rod is arranged along the width direction of the slideway to increase the contact area with the reinforcing rib 41. The electric telescopic rod expands and contracts along the direction perpendicular to the bottom of the slideway to drive the reinforcing rib 41 to fall from the outlet in sequence through the ejecting rod; the electric telescopic rod can act in sequence under the control of the control mechanism to realize the sequential placement of the reinforcing ribs 41; the outlet of the slideway is located above the vibrating piece to achieve synchronous movement with the nozzle 11 and meet the requirement of placing the reinforcing ribs 41; or, it can also be done manually by placing the reinforcing ribs 41 on the vibrating piece manually following the printing of the nozzle 11.

[0056] Among them, the detection component 5 includes a vibration sensor. The vibration sensor includes a high-sensitivity piezoelectric sensing element such as a piezoelectric sheet, with a frequency response range of 5 - 100 kHz, a size of 5×5×1 mm, a sensitivity ≥ -70 dB, and a frequency response flatness of ±3 dB. When the concrete material vibrates, it will exert pressure on the piezoelectric sheet, generating a certain voltage. By collecting and analyzing the voltage signal, the vibration signal can be obtained. The piezoelectric sheet can be attached to the upper surface of the upper-layer concrete of the interface. When printing the next layer of concrete on the upper surface of the upper-layer concrete of the interface, the piezoelectric sheet can be removed from the upper surface of the concrete for the next use. Basic parameters of vibration detection: Emission vibration frequency: 10 - 50 Hz, adjustable according to the concrete mix; Vibration duration: 0.1 s; Sampling frequency: 1000 Hz; Detection interval: 5 times per second.

[0057] In addition, other conventional detection components can also be used as long as they can detect the vibration frequency at the interface.

[0058] The control mechanism is set as a high-performance industrial computer, with a processor ≥ 8 cores and a main frequency ≥ 3.0 GHz; a real-time operating system with a response time < 10 ms; The control mechanism is communicatively connected to the detection component 5, and the signal of the detection component 5 is transmitted to the band-stop filter through the signal amplification circuit and then to the band-pass filter; Sampling frequency: 1000 Hz, signal resolution: 16 bits; Filter out 50 / 60 Hz power frequency interference through the band-stop filter; Retain the effective vibration signal of 5 - 100 Hz through the band-pass filter; And the adjustable gain of the signal amplification circuit is 0 - 40 dB; The processing capacity of the control mechanism ≥ 100 MIPS to ensure real-time analysis; RAM random access memory ≥ 256 MB to meet the high-speed data caching requirements; The storage medium capacity ≥ 32 GB for recording historical data; Connected to the wireless communication module of the detection component 5: Supports WiFi wireless / Bluetooth Bluetooth for real-time data transmission.

[0059] In addition, a system calibration process can also be carried out: Calibrate using a standard fluid (silicone oil with a known viscosity); Conduct vibration tests on concrete at different curing stages to establish a calibration curve; Establish the corresponding relationship between the vibration wave attenuation ratio R value and the degree of fluidization through piecewise linear fitting; After calibration, the system accuracy should reach ±5%.

[0060] Among them, the method for real-time evaluation of the degree of fluidization is as follows: Calculation of the vibration wave attenuation ratio: R = A2 / A1, where A1 is the emission amplitude and A2 is the received amplitude; Use the time-domain peak detection method to extract A1 and A2; In each detection cycle, continuously collect 10 groups of data and take the average to reduce random errors.

[0061] Fluidization degree evaluation criteria: Solid concrete: The R value is usually 0.6 - 0.8; Semi-fluidized state: The R value is usually 0.3 - 0.6; Fully fluidized state: The R value is usually 0.1 - 0.3; Preset fluidization threshold: For standard printed concrete, usually take R = 0.4; Introduce the spectrum analysis method: Perform fast Fourier transform (FFT) on the vibration signal; Analyze the spectrum characteristics and extract the characteristic frequencies; Combine the time-domain and frequency-domain information to improve the accuracy of fluidization detection.

[0062] Among them, the adaptive adjustment method of vibration parameters based on fluidization detection is as follows: When the R value > 0.5 (insufficient fluidization): Increase the vibration frequency by 2 - 5 Hz; and / or, increase the vibration amplitude by 0.1 - 0.2 mm; and / or, extend the vibration time by 0.05 - 0.1 seconds.

[0063] When 0.3 ≤ R value ≤ 0.5 (moderate fluidization): Keep the current vibration parameters unchanged.

[0064] When the R value < 0.3 (excessive fluidization): Decrease the vibration frequency by 2 - 5 Hz; and / or, decrease the vibration amplitude by 0.1 - 0.2 mm; and / or, shorten the vibration time by 0.05 seconds.

[0065] Adjustment range of vibration parameters for the vibration plate: Vibration frequency adjustment range: 5 - 60 Hz; Vibration amplitude adjustment range: 0.1 - 2.0 mm; Vibration time adjustment range: 0.05 - 0.5 seconds.

[0066] In addition, the Bayesian optimization algorithm can also be applied to predict the optimal vibration parameters based on historical data; As the printing process progresses, continuously optimize the parameter selection strategy; Establish a database of concrete types, ambient temperatures, time intervals, and optimal vibration parameters.

[0067] Furthermore, multiple detection components 5 can be set in the width direction of the vibration plate, usually 3 - 5. The control mechanism calculates the coefficient of variation of the R value at each point to evaluate the fluidization uniformity; Among them, based on the R value under the specific vibration signal emitted by the detection component 5 as the benchmark, the coefficient of variation is defined as the degree to which the R value of the detection signal of the detection component 5 deviates from the benchmark R value; Uniformity judgment criteria: Coefficient of variation < 10%: Good fluidization uniformity; Coefficient of variation 10 - 20%: General fluidization uniformity; Coefficient of variation > 20%: Poor fluidization uniformity, and the vibration parameters need to be adjusted. For the case of insufficient uniformity, adjust the vibration mode: Adopt sweep-frequency vibration (changing from low frequency to high frequency); or adopt composite vibration (simultaneously containing multiple frequency components); or adjust the vibration direction to increase the vibration component perpendicular to the interface.

[0068] Furthermore, the data recording and analysis of the control mechanism can be extended to include the following in subsequent applications: Establish a data recording system to save the following information in real time: printing coordinate positions; timestamps; ambient temperature and humidity; vibration parameters (frequency, amplitude, duration); fluidization degree R value; vibration parameter adjustment records.

[0069] Develop a data visualization interface to display: a fluidization degree heat map to intuitively show the fluidization quality distribution of the entire printing structure; a trend graph to show the change of the fluidization degree over time; and anomaly point markers to highlight the positions with insufficient or excessive fluidization. Establish a printing quality assessment report system to automatically generate: overall fluidization quality statistics (average R value, standard deviation, etc.); identification of potential risk areas; improvement suggestions, etc.

[0070] In addition, fluidization detection methods under special working conditions: High-strength concrete (strength grade > C50): lower the fluidization threshold to R = 0.35; increase the detection frequency to 8 - 10 times per second. Low-temperature environment (<10°C): raise the fluidization threshold to R = 0.45; extend the sampling time to 0.15 seconds. High-temperature environment (>35°C): lower the fluidization threshold to R = 0.3; increase the vibration cooling time to prevent excessive fluidization.

[0071] Furthermore, the detection component 5 can also include a thermocouple arranged inside the vibrating plate to monitor the temperature change at the interface. If the temperature rises by more than 2°C, it indicates that the material starts to fluidize; the control mechanism dynamically adjusts the vibration parameters according to the temperature change and the material state: when the temperature change is not obvious (<1°C), increase the vibration frequency by 5 Hz and / or the amplitude by 0.2 mm; when the temperature change is obvious (>3°C), decrease the vibration frequency by 5 Hz and / or the amplitude by 0.2 mm to prevent excessive fluidization.

[0072] Specific examples are used in the present invention to illustrate the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A 3D printing concrete interface reinforcement method, characterized in that: It includes the following steps: Print the nth layer of concrete, where n is an integer; Place the vibrating member (21) on the upper surface of the nth layer of concrete; Print the (n + 1)th layer of concrete on the upper surface of the nth layer of concrete. The vibrating member (21) vibrates at the interface, causing the concrete at the interface between the nth layer of concrete and the (n + 1)th layer of concrete to be fluidized and capable of contacting and fusing after the vibrating member (21) is removed.

2. The 3D printing concrete interface reinforcement method according to claim 1, wherein: When printing the (n + 1)th layer of concrete on the upper surface of the nth layer of concrete, the vibrating member (21) moves synchronously with the printing stroke of the (n + 1)th layer of concrete at the interface and vibrates, so that the concrete at the interface between the nth layer of concrete and the (n + 1)th layer of concrete is fluidized and gradually contacts and fuses as the vibrating member (21) moves.

3. The 3D printing concrete interface reinforcement method according to claim 1, characterized in that: When printing the (n + 1)th layer of concrete on the upper surface of the nth layer of concrete and the vibrating member (21) vibrates at the interface, inject strengthening material synchronously at the interface.

4. The 3D printing concrete interface reinforcement method according to claim 1, wherein: The vibrating member (21) is set as a vibrating plate, and the evacuation end of the vibrating plate has a wavy structure.

5. The 3D printing concrete interface reinforcement method according to claim 4, characterized in that: Reinforcing bars (41) are left at the part of the vibrating plate where the (n + 1)th layer of concrete is not covered, and the reinforcing bars (41) can be separated from the vibrating plate when the vibrating plate evacuates from the interface between the nth layer of concrete and the (n + 1)th layer of concrete and are left at the interface.

6. The 3D printing concrete interface reinforcement method according to claim 5, characterized in that: The reinforcing bars (41) are set in a wavy shape, and the vibration process of the vibrating plate can cause the reinforcing bars (41) to flip and be left at the interface at an angle relative to the horizontal plane.

7. The 3D printing concrete interface reinforcement method according to claim 3, characterized in that: A one-way fluid channel (211) is arranged inside the vibrating member (21). One end of the one-way fluid channel (211) is used to communicate with the liquid injection mechanism (3), and the other end extends to the evacuation end of the vibrating member (21) and communicates with the interface. The strengthening material can be injected to the interface through the one-way fluid channel (211).

8. The 3D printing concrete interface reinforcement method according to claim 1, characterized in that: It also includes the following steps: Detect the fluidization degree at the interface where the nth layer of concrete and the (n + 1)th layer of concrete contact and fuse. It can also monitor the temperature change at the interface when the vibrating member (21) vibrates at the interface. The vibration parameters of the vibrating member (21) are adjusted in real time based on the fluidization degree detection information or temperature change information.

9. A 3D printed concrete interface reinforcement system, characterized in that: It includes: A 3D printing mechanism (1) for printing concrete layer by layer; A vibration mechanism (2), including a vibrating member (21) and a vibration driver (22). The vibrating member (21) is used to be placed on the upper surface of the nth layer of concrete, and the vibrating member (21) can move synchronously with the printing path of the 3D printing mechanism (1); the vibration driver (22) is connected to the vibrating member (21) and can drive the vibrating member (21) to vibrate.

10. The 3D printing concrete interface reinforcement system according to claim 9, wherein: It also includes: A liquid injection mechanism (3). A one-way fluid channel (211) is arranged inside the vibrating member (21). One end of the one-way fluid channel (211) communicates with the liquid injection mechanism (3), and the other end extends to the evacuation end of the vibrating member (21) and communicates with the interface. The liquid injection mechanism (3) can inject the strengthening material to the interface through the one-way fluid channel (211); An arrangement mechanism (4) for arranging the reinforcing bars (41) on the vibrating member (21); A detection component (5) for detecting the fluidization degree information at the interface of contact fusion and / or monitoring the temperature change information at the interface when the vibrating member (21) vibrates at the interface; A control mechanism, communicatively connected to the detection component (5) for receiving the detected information; the control mechanism can also be communicatively connected to the vibration driver (22) and can adjust the vibration parameters of the vibrating member (21).

Images