A method for 3D printing thin-walled concrete components

Abstract

A 3D printing method for thin-walled concrete components, specifically relating to the field of 3D printing concrete technology, includes the following steps: model acquisition and parameter setting; generating corresponding paths for each printing layer based on the relationship between wall thickness T and print head nozzle diameter D; and printing execution. This invention requires no changes to existing printing equipment and concrete materials. Through path planning optimization, it precisely matches suitable paths for printing layers of different wall thicknesses. This not only breaks the continuity of weak surfaces between layers formed by continuous contour path printing but also avoids defects such as slurry accumulation and incomplete compaction that occur when a layer's wall thickness is not an integer multiple of the print head nozzle diameter and is printed using an alternately assigned contour layer path. This method significantly improves the interlayer bonding strength and overall mechanical uniformity of the component. It is simple, low-cost, and highly versatile, suitable for 3D printing of thin-walled components with equal or variable wall thicknesses, effectively avoiding the drawbacks of adjusting process parameters and changing equipment.

Description

Technical Field

[0001] This invention relates to the field of 3D printing concrete technology, and more particularly to a method for 3D printing thin-walled concrete components. Background Technology

[0002] 3D printing concrete technology (concrete additive manufacturing) has shown great promise in the construction field due to its advantages such as automation, high degree of freedom, and no need for formwork. This technology constructs components by stacking concrete slurry layer by layer. However, it is precisely this layer-by-layer stacking process that leads to significant anisotropy in the mechanical properties of the components: the subsequent layer of material is stacked on the "cold joint" of the previous layer that has already partially solidified, resulting in interlayer bond strength that is much lower than that of the material itself, forming continuous weak mechanical surfaces that seriously affect the load-bearing capacity and durability of the components.

[0003] In existing path planning research, some schemes have proposed a path design that alternates orthogonally between contour layers and interlocking layers, which to some extent breaks the continuity of weak surfaces between layers. However, such methods are all general fixed designs for components with equal wall thickness and do not consider the matching between the component wall thickness and the print head nozzle diameter. When printing components with variable wall thickness, if the wall thickness of a certain printing layer is not an integer multiple of the print head nozzle diameter, printing that printing layer using the contour layer path allocated in an alternating sequence will result in defects such as slurry accumulation and incomplete molding.

[0004] Therefore, there is currently a lack of a method that can solve the interlayer weakness problem caused by using contour layer printing paths for continuous printing layers, and meet the printing requirements of printing layers with different wall thicknesses, without changing the existing 3D printing hardware, concrete materials and core process parameters. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a 3D printing method for thin-walled concrete components.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for 3D printing thin-walled concrete components includes the following steps:

[0008] Step 1: Model acquisition and parameter setting. Acquire the three-dimensional digital model of the thin-walled concrete component to be printed, extract the component wall thickness value T corresponding to the printing height of each layer in the model, and determine the nozzle diameter D of the print head of the 3D printing equipment.

[0009] Step 2: Based on the relationship between wall thickness T and printhead nozzle diameter D, generate corresponding paths for each printing layer;

[0010] Wherein, if T=n×D, where n is a positive integer, a continuous loop path is generated, and its dominant direction is the first dominant direction, which constitutes the contour layer path; if T is not a positive integer multiple of D, a reciprocating printing path is generated, and its dominant direction is the second dominant direction, which forms an angle of 80°~100° with the first dominant direction, which constitutes the interlocking layer path; if three consecutive printing layers all satisfy T=n×D and n≥2, then the contour layer path of the middle printing layer is replaced with the interlocking layer path; Step 3: Printing execution, controlling the printing equipment to print the thin-walled concrete component layer by layer according to the path generated by each printing layer.

[0011] Furthermore, in step two, if there are three consecutive printing layers with interlocked layer paths, the angle between the second dominant direction and the first dominant direction of each interlocked layer path of the consecutive printing layers is the same.

[0012] Furthermore, the interlocking layer path is a sawtooth path.

[0013] Furthermore, the nozzle diameter D of the printhead is 8mm~12mm.

[0014] Furthermore, the wall thickness at any position of the thin-walled concrete component to be printed is no greater than 1 / 10 of the total height of the thin-walled concrete component to be printed.

[0015] Furthermore, the thin-walled concrete component to be printed includes thin-walled concrete components with equal wall thickness and thin-walled concrete components with variable wall thickness.

[0016] Furthermore, the second dominant direction forms a 90° angle with the first dominant direction.

[0017] The beneficial effects of this invention are:

[0018] This invention proposes a 3D printing method for thin-walled concrete components. It introduces an adaptive path selection rule that matches the wall thickness with the print head nozzle diameter, and an interlocking reinforcement rule for continuous contour layers, achieving path adaptation and precise control of weak surfaces across the entire printing process. This invention requires no changes to existing printing equipment or concrete materials. Through path planning optimization, it precisely matches and adapts paths for printing layers of different wall thicknesses. This not only breaks the continuity of weak surfaces between layers formed by continuous contour path printing, but also avoids defects such as slurry accumulation and incomplete compaction that occur when a layer's wall thickness is not an integer multiple of the print head nozzle diameter and is printed using an alternately assigned contour layer path. This method significantly improves the interlayer bonding strength and overall mechanical uniformity of the components. The process is simple, low-cost, and highly versatile, suitable for 3D printing various thin-walled concrete components such as equal-thickness and variable-thickness concrete walls and columns, effectively avoiding the drawbacks of adjusting process parameters and changing equipment. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram illustrating the steps of a 3D printing method for thin-walled concrete components according to the present invention;

[0021] Figure 2 This is a schematic diagram of the contour layer path of the present invention;

[0022] Figure 3 This is a schematic diagram of the interlocking layer path of the present invention;

[0023] Figure 4 This is one of the schematic diagrams of the printing process of the present invention;

[0024] Figure 5 This is the second schematic diagram of the printing process of the present invention;

[0025] Figure 6 This is a schematic diagram of a thin-walled concrete member with variable wall thickness. Detailed Implementation

[0026] The following is combined Figure 1-6 The present invention will be described in detail below.

[0027] A method for 3D printing thin-walled concrete components includes the following steps:

[0028] Step 1: Model acquisition and parameter setting. Acquire the three-dimensional digital model of the thin-walled concrete component to be printed, extract the component wall thickness value T corresponding to the printing height of each layer in the model, and determine the nozzle diameter D of the print head of the 3D printing equipment.

[0029] Step 2: Based on the relationship between wall thickness T and printhead nozzle diameter D, generate corresponding paths for each printing layer;

[0030] Wherein, if T=n×D, where n is a positive integer, a continuous loop path is generated, and its dominant direction is the first dominant direction, which constitutes the contour layer path; if T is not a positive integer multiple of D, a reciprocating printing path is generated, and its dominant direction is the second dominant direction, which forms an angle of 80°~100° with the first dominant direction, which constitutes the interlocking layer path; if three consecutive printing layers all satisfy T=n×D and n≥2, then the contour layer path of the middle printing layer is replaced with the interlocking layer path; Step 3: Printing execution, controlling the printing equipment to print the thin-walled concrete component layer by layer according to the path generated by each printing layer.

[0031] Specifically, in step one, after extracting and determining the T and D values, it is also necessary to set basic printing parameters, including but not limited to the printing layer height, printhead running speed, material pumping speed, etc. These basic printing parameters are fixed throughout the process and do not require real-time adjustment based on the printing layer thickness. The printing layer height ranges from 6mm to 10mm, the printhead running speed ranges from 40mm / s to 60mm / s, and the material pumping speed is adjusted according to the actual conditions such as the nozzle diameter of the printhead used and the rheological properties of the concrete slurry to ensure continuous and stable extrusion of the concrete slurry.

[0032] In step two, when the wall thickness of the continuous printing layer is equal to the printhead nozzle diameter (T=D, i.e., n=1), it is not necessary to replace the outline layer path of any of the printing layers with the interlocking layer path. The outline layer interlocking reinforcement rule is only executed when three consecutive layers satisfy T=n×D (n≥2).

[0033] A print layer using a contour layer print path can be simply referred to as a contour layer, and a print layer using an interlock layer print path can be simply referred to as an interlock layer.

[0034] In this embodiment, in step two, if there are three consecutive printing layers with interlocked layer paths, the angle between the second dominant direction and the first dominant direction of each interlocked layer path in the consecutive printing layers is the same. This setting, while ensuring the core interlocking effect, eliminates the need for alternating direction modifications (i.e., angle modifications) between adjacent interlocked layers, thus simplifying the path generation algorithm.

[0035] The angle between the second dominant direction of all interlocking layers of the entire thin-walled concrete component to be printed and the first dominant direction of the contour layer only needs to be between 80° and 100°. Except for continuous contour layers, the angles do not need to be the same. For example, if layers 1-3 and layer 6 are both contour layers, then the angles corresponding to layers 1-3 can be 91°, and the angles corresponding to layer 6 can be 89°. It is not required that all of them use 91° or 89°.

[0036] In this embodiment, the interlocking layer path is a sawtooth path.

[0037] In this embodiment, the nozzle diameter D of the printhead is 8mm~12mm.

[0038] In this embodiment, the wall thickness at any position of the thin-walled concrete component to be printed is no greater than 1 / 10 of the total height of the thin-walled concrete component to be printed.

[0039] In this embodiment, the thin-walled concrete components to be printed include thin-walled concrete components with uniform wall thickness and thin-walled concrete components with variable wall thickness. For thin-walled concrete components with uniform wall thickness, for example, if the wall thickness T of a thin-walled concrete component with uniform wall thickness is 10mm, the nozzle diameter of the print head is directly set to D=10mm. According to step two, each layer adopts the contour layer path. Since T equals D, there is no problem of weak surfaces between layers.

[0040] In this embodiment, the second dominant direction forms a 90° angle with the first dominant direction.

[0041] Specifically, the contour layer printing path ensures good in-plane mechanical continuity of the printed layer. The interlocking layer printing path aims to form an interlocking structure between layers through orthogonal or approximately orthogonal interlacing with the contour layer printing path. This optimizes the overall stress mechanism of the component from a topological perspective, achieving effective stress transfer between layers. The interlayer bond strength is improved by more than 20% compared to traditional continuous contour printing, and mechanical anisotropy is significantly improved. Orthogonal interlacing refers to the second dominant direction forming a 90° angle with the first dominant direction. Approximately orthogonal interlacing refers to the second dominant direction forming an angle of 80°-100° with the first dominant direction, but not 90°. The angle range of 80°-100° considers the possible slight deviations in the path generation algorithm and the smooth transition of the path in actual printing. While ensuring the interlocking effect between layers, it also considers the feasibility of the process. The preferred angle is 90°. See [link to documentation]. Figure 3 As shown, the interlocking layer path is specifically a square zigzag path, and the arrow direction is the second dominant direction. Figure 2 The direction of the arrow in the image is the primary dominant direction. For example... Figure 4 and Figure 5 As shown, the second dominant direction forms a 90° angle with the first dominant direction.

[0042] The specific implementation steps of the 3D printing method for thin-walled concrete components proposed in this invention are as follows:

[0043] Example 1: To print a variable-thickness concrete thin-walled wall with a total height of 300mm, where the wall thickness gradually changes along the height, this is a typical variable-thickness concrete thin-walled component in building engineering. All path angles are 90° orthogonal, and the interlocking layers are square sawtooth paths.

[0044] Step 1: Model Acquisition and Parameter Setting

[0045] A 3D digital model of the variable-thickness concrete thin-walled wall is obtained. The 3D digital model is imported into 3D printing slicing software. The component is sliced ​​at equal intervals along the vertical direction according to the preset printing layer height of 6-10mm. The software automatically extracts the width of the wall thickness of each slice section as the wall thickness value T of the corresponding printing layer. If it is a variable-thickness layer, the average width of the section of the layer is taken as the T value. Finally, the wall thickness value T of each printing layer is extracted through model analysis: the wall thickness of the 1st to 3rd layers is T=30mm; the wall thickness of the 4th to 6th layers is T=25mm; the wall thickness of the 7th to 9th layers is T=20mm; the wall thickness of the 10th layer and thereafter is T=10mm.

[0046] Conventional 3D printing equipment for concrete was selected, and the nozzle diameter of the print head was determined to be D=10mm. The basic printing parameters were set as follows: the printing layer height was 10mm, the total number of printing layers was 30, and the print head running speed was 50mm / s. Based on the nozzle diameter and the rheological properties of C40 grade 3D printed concrete slurry, the material pumping speed was matched to 60mL / min to ensure continuous and stable extrusion of the slurry. The above basic parameters were kept fixed throughout the printing process without any adjustment.

[0047] Step 2: Path Generation

[0048] Layers 1-3: All satisfy the condition T=n×D (n≥2), which are three consecutive contour-printable layers. The continuous wrapping path of the contour layer in layer 2 is replaced with the interlocking reciprocating printing path. The contour layer is a continuous wrapping path in the horizontal direction, which is the first dominant direction. The interlocking layer is a rectangular zigzag path, which is a vertical reciprocating printing path, which is the second dominant direction.

[0049] Layers 4-6: Wall thickness T = 25mm (not a positive integer multiple of D). The unified path rule for continuous interlocking layers is executed. Layers 4-6 all adopt a reciprocating printing path orthogonal to the contour layer in this scheme. Refer to the path of layer 2 mentioned above.

[0050] Layers 7-9: All satisfy the condition T=n×D (n≥2), which are three consecutive layers that can be outlined and printed. Replace the continuous wrapping path of the outline layer in layer 8 with the interlocking reciprocating printing path, and keep the path direction consistent with layers 1-3.

[0051] Layer 10 and above: all satisfy the condition T=D (n=1), there is no need to execute the interlocking reinforcement rule, just maintain the continuous wrapping path of the contour layer, there is no need to replace it with the interlocking layer path, and both molding efficiency and interlayer performance are taken into account.

[0052] Step 3: Print Execution

[0053] The generated path code is imported into the printing control system, which controls the 3D printing equipment to print layer by layer according to the generated orthogonal alternating path. During the printing process, the basic parameters are kept fixed, and the hardware structure and printing materials are not changed.

[0054] The final printed variable-thickness concrete thin-walled wall is free from defects such as slurry accumulation, incomplete forming, and collapse. The forming accuracy of each printed layer is controlled within ±0.5mm. Due to the implementation of interlocking reinforcement rules, the weak surfaces between continuous contour printed layers (n≥2) are effectively broken. The continuous interlocking layers maintain the same path in the same direction, which simplifies the printing operation. At the same time, the positive interlocking core effect with the contour layer is not affected. The overall mechanical uniformity of the component is significantly improved, with no obvious mechanical anisotropy, which fully meets the requirements of building engineering for the load-bearing capacity, seismic resistance, and durability of concrete thin-walled components.

[0055] Example 2 (for reference):

[0056] This reference example addresses the scenario where the first six layers of a variable-thickness concrete thin-walled component continuously satisfy T=n×D (n≥2). It details the recursive reinforcement rule of "replacing the middle layer with an interlocking layer when there are three consecutive contour layers" to verify the effectiveness of this invention in controlling weak surfaces of long continuous contour layers in variable-thickness components. All path angles are 90° orthogonal, and the interlocking layer is a square sawtooth path.

[0057] The component to be printed is a variable-thickness concrete thin-walled column with a total height of 600mm. The wall thickness at any position of the component is no greater than 1 / 10 (60mm) of the total height, which meets the requirements of this invention for thin-walled concrete components. The wall thickness of the component gradually changes along the height direction (7 layers and beyond simultaneously include wall thickness segments where T is an integer multiple of D and not an integer multiple of D), with the 1st to 6th layers being of uniform thickness, with a wall thickness T=30mm. The nozzle diameter of the print head of the selected 3D printing equipment is D=10mm (i.e., T=3D, n=3≥2), the preset printing layer height is 10mm, and the total number of printing layers for the component is 60. The basic printing parameters are set as follows: print head running speed 45mm / s, concrete material pumping speed 65mL / min, and all basic parameters are fixed throughout the printing process without real-time adjustment.

[0058] Step 1: Model Acquisition and Parameter Setting

[0059] A three-dimensional digital model (STL format) of the variable wall thickness concrete thin-walled column is obtained and imported into a slicing software for building 3D printing. The component is sliced ​​at equal intervals along the vertical direction (Z-axis) according to a preset printing layer height of 10mm. The software automatically extracts the width of the cross-sectional profile of each slice. The cross-sectional width of the first to sixth layers is 30mm (equal thickness section), that is, the wall thickness value T=30mm of the sixth layer. The seventh layer and above are variable wall thickness sections (including different sections where T is an integer multiple of D and not an integer multiple of D). The specific path generation rules are executed according to the present invention, which will not be detailed here.

[0060] Parameters were verified and fixed. The nozzle diameter of the printhead was determined to be D=10mm. It was verified that the T=30mm of the first to sixth layers was not greater than 1 / 10 (60mm) of the total height of the component of 600mm, which meets the thin-walled component limit of the present invention. Basic parameters such as printhead running speed and material pumping speed were set synchronously and kept constant throughout the process without being adjusted with the change of printing layers.

[0061] Step 2: Generate paths for layers 1-6 (replace the middle layer with an interlocking layer for three consecutive contour layers).

[0062] For the scenario where layers 1 to 6 of a variable wall thickness component continuously satisfy T = n × D (n ≥ 2), the core rule of "if three consecutive layers are printable layers (T ≥ 2D), then the middle layer of those three layers is replaced with an interlocking layer" is used for recursive judgment. The specific operation is as follows:

[0063] Group 1: Judgment and reinforcement of layers 1-3

[0064] If the first to third layers are determined to be T=3D (n≥2) printable contour layers, the reinforcement rules of this invention are executed, and the continuous contour layer path of the second layer (the middle layer of the three layers) is replaced with a zigzag interlocking layer path; wherein the first and third layers retain the horizontal ring-shaped continuous contour layer path (first dominant direction), and the second layer is a vertical zigzag interlocking layer path (second dominant direction, orthogonal to the first dominant direction at 90°).

[0065] Group 2: Judgment and reinforcement of layers 3-5

[0066] Recursively judge layers 3 to 5. If the group still continuously satisfies the printable contour condition of T=3D (n≥2), execute the reinforcement rule and replace the continuous wrap-around contour path of layer 4 (the middle layer of the three layers) with a zigzag interlocking layer path. Among them, layers 3 and 5 retain the horizontal ring contour path, and layer 4 is a vertical zigzag interlocking layer path (orthogonal to the first dominant direction at 90°).

[0067] Group 3: Judgment of layers 5-6 (less than 3 layers, no reinforcement needed)

[0068] Recursively judging layers 5 and 6, only 2 layers satisfy T=3D (n≥2), which does not meet the reinforcement triggering condition of "3 consecutive layers". Therefore, there is no need to insert an interlocking layer. Layers 5 and 6 retain the continuous loop path of the horizontal ring contour layer.

[0069] Final path layout for layers 1-6

[0070] After recursive reinforcement, layers 1, 3, 5, and 6 are outline layers, and layers 2 and 4 are interlocking layers, forming an interlayer layout of "outline-interlocking-outline-interlocking-outline-outline"; the variable wall thickness sections from layer 7 onwards generate corresponding paths according to the rules of this invention, which will not be described in detail here.

[0071] Step 3: Print Execution

[0072] The path data of layers 1 to 6 and the path data of the remaining 54 layers are summarized, exported as path codes that can be recognized by the printing equipment, and imported into the 3D printing control system. The printing equipment is controlled to print thin-walled concrete columns layer by layer according to the generated path. During the printing process, the hardware structure of the equipment is not changed, the concrete printing material is not changed, the basic printing parameters are kept constant, and the concrete slurry is stacked layer by layer according to the layout of "contour layer-interlocking layer".

[0073] Implementation effect

[0074] The final printed variable-wall-thickness concrete thin-walled column is free from defects such as slurry accumulation and incomplete molding. The molding accuracy of the first to sixth layers of equal thickness is controlled within ±0.5mm. Due to the adoption of a progressive reinforcement design of "replacing the middle layer with an interlocking layer after three consecutive contours", the vertical through-weak surface that is easy to form in the first six layers of continuous contour printing is completely avoided. The concrete between layers is tightly bonded, the overall mechanical uniformity of the component is significantly improved, and the interlayer shear strength is improved compared with the traditional continuous contour printing scheme. The variable-wall-thickness sections from the seventh layer onwards are also accurately adapted through the path rules of this invention. The entire printing process is achieved only through path planning optimization, without the need to adjust process parameters or modify printing equipment. The process is simple and convenient to operate, and fully meets the printing quality and structural performance requirements of variable-wall-thickness thin-walled components in building engineering.

[0075] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand and implement the present invention. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for 3D printing thin-walled concrete components, characterized in that, Includes the following steps: Step 1: Model acquisition and parameter setting. Acquire the three-dimensional digital model of the thin-walled concrete component to be printed, extract the component wall thickness value T corresponding to the printing height of each layer in the model, and determine the nozzle diameter D of the print head of the 3D printing equipment. Step 2: Based on the relationship between wall thickness T and printhead nozzle diameter D, generate corresponding paths for each printing layer; Wherein, if T=n×D, where n is a positive integer, a continuous loop path is generated, and its dominant direction is the first dominant direction, which constitutes the contour layer path; if T is not a positive integer multiple of D, a reciprocating printing path is generated, and its dominant direction is the second dominant direction, which forms an angle of 80°~100° with the first dominant direction, which constitutes the interlocking layer path; if three consecutive printing layers all satisfy T=n×D and n≥2, then the contour layer path of the middle printing layer is replaced with the interlocking layer path; Step 3: Printing execution, controlling the printing equipment to print the thin-walled concrete component layer by layer according to the path generated by each printing layer.

2. The 3D printing method for thin-walled concrete components as described in claim 1, characterized in that, In step two, if there are three consecutive printing layers with interlocked layer paths, the angle between the second dominant direction and the first dominant direction of each interlocked layer path of the consecutive printing layers is the same.

3. The 3D printing method for thin-walled concrete components as described in claim 1, characterized in that, The interlocking layer path is a sawtooth path.

4. The 3D printing method for thin-walled concrete components as described in claim 1, characterized in that, The nozzle diameter D of the printhead is 8mm~12mm.

5. The 3D printing method for thin-walled concrete components as described in claim 1, characterized in that, The wall thickness at any position of the thin-walled concrete component to be printed is no greater than 1 / 10 of the total height of the thin-walled concrete component to be printed.

6. The 3D printing method for thin-walled concrete components as described in claim 1, characterized in that, The thin-walled concrete components to be printed include thin-walled concrete components with equal wall thickness and thin-walled concrete components with variable wall thickness.

7. A method for 3D printing thin-walled concrete components as described in any one of claims 1-6, characterized in that, The second dominant direction forms a 90° angle with the first dominant direction.

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