Practical slicing and path planning method for 3D printing large-scale building

Abstract

The invention relates to the technical field of 3D printing, and discloses a practical slicing and path planning method for 3D printing of a large-scale building, which comprises the following steps of: performing global path planning on a building model in horizontal and vertical directions by avoiding obstacles, and dividing a printing area; the printing area is sliced; a local printing path is determined for the position of the specific wall, a printing path of walking the outer contour of the wall firstly and then walking the diagonal web member of the truss in the wall is made for the stressed wall, and a Z shape is formed in the inner part of the outer contour of the non-stressed wall firstly; the lower-layer end point is an upper-layer start point; and analyzing whether the interlayer interval time exceeds the initial setting time of the concrete. The working radius of the 3D printer is free of obstacles and covers a stress wall, and the number of moving times of the printer is minimum; continuous printing of the wall is achieved, it is guaranteed that concrete printing is not interrupted, and the idle running speed is reduced; sharp turning of the printing head can be avoided, and the printing material consumption is small; the concrete meets constructability and printing appearance quality before initial setting, and meets eccentric compressive strength, rigidity and stability after final setting.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing, and in particular to a practical slicing and path planning method for 3D printing large-scale buildings. Background Art

[0002] 3D printing technology is a technology that creates three-dimensional entities by stacking materials layer by layer. This technology uses computer-controlled printers based on digital design files to stack materials such as plastics, metals, concrete, etc. layer by layer according to a predetermined design, and finally forms a physical model or product. The application of 3D printing technology in the construction industry uses large-scale 3D printers and concrete, mortar or other building composite materials as printing materials. According to digital design drawings, the walls, structures and other components of the building are printed layer by layer, allowing architects and designers to quickly model and prototype, and realize personalized customization of architectural elements. It has the characteristics of automated operation, reduced material waste, and high efficiency, and can quickly complete complex building structures under continuous operation.

[0003] The key technical links of printing buildings with 3D printing technology include slicing, printing path planning and printing programming. Traditional slicing algorithms include fixed-thickness slicing method and variable-thickness slicing method. The principle is to use slicing software (such as Cura) to mesh the facade surface of the STL model to obtain approximate triangular facets for vertical segmentation. The intersection of the triangular facets and the horizontal section is the printing path. This slicing algorithm is more suitable for desktop printers, not for large-scale building printing and has large errors.

[0004] The print path is the moving trajectory of the three-dimensional coordinate point of the printer nozzle center. The distance between the coordinate points is the distance between the dividing points on the print path curve. The line connecting the dividing points approximates the print path curve between the start and end points. The path planning algorithms currently used in concrete 3D printing technology are: Zigzag algorithm, which is the most common printing method at present, but it has many sharp turns. For shapes with complex boundaries or hollow shapes, this disadvantage will be very obvious; Contour parallel algorithm, composed of equally spaced parallel lines, can avoid too many sharp turns, but it leads to more contours and the contours are not connected; Fermat spiral algorithm, composed of two intertwined sub-spirals, one inward and one outward, this algorithm solves the problem of avoiding too many sharp turns and the disconnection between contours, but when used for architectural 3D printing, due to the poor anisotropy of the spiral path, after the slicing of the three-dimensional model, if the two adjacent layers of cross-section use the same type of spiral path, the paths between adjacent layers will be superimposed on each other, which is not conducive to the mechanical strength of the printed model in the lateral direction; Galapagos curve genetic algorithm, which uses genetic algorithms to optimize the printing path curve, and evaluates and improves the degree of curve fit through different parameters and functions to achieve specific design or construction goals, but the actual application is very complicated.

[0005] In view of the fact that the above-mentioned architectural 3D printing path planning algorithm and path optimization algorithm are complex and each has its own advantages and disadvantages and scope of application, it is necessary to study and develop a practical slicing and path planning method for 3D printing large-scale buildings. Summary of the invention

[0006] In view of the problems raised by the background technology, the present invention discloses a practical slicing and path planning method for 3D printing large-scale buildings. By providing steps such as global path planning, slicing, and printing path planning of a building model, a complete set of practical methods for 3D printing large-scale buildings is provided, which can be applicable to buildings with complex shapes, and at the same time achieve the purposes of continuous printing path, avoiding sharp turns of the print head, reducing the amount of printing material used, and ensuring that the printed building meets the strength and stability requirements.

[0007] The practical slicing and path planning method for 3D printing large-scale buildings of the present invention comprises the following steps: S1, prepare the building model, 3D printing equipment and digital model adaptation software: complete the in-depth design of the building design digital model, reserve and embed cable ducts for water and electricity pipes; select the 3D printing equipment and robot arm model according to the plane and facade dimensions of the project; import the building design digital model into the digital model adaptation software; S2, global path planning for the building model: global path planning is performed for the building model in the horizontal and vertical directions to avoid obstacles, and the printing area is divided. The machine position setting in each area must meet the working radius range of the robot arm, and the printing order is determined according to the position relationship of each printing area; S3, slicing each printing area: the number of slices = the printing height of a printing area / the printing layer thickness, the printing layer thickness is less than 1 / 2 the nozzle diameter; the printing order of each printing layer is determined from bottom to top according to the slices; S4, plan the printing path for each printing layer: for wall positions with specific requirements including reinforced columns and segmented printing joints, first determine the local printing path; for load-bearing walls with a thickness of ≥200mm, make a printing path that first follows the outer contour of the wall and then follows the diagonal web members of the trusses inside the wall, and connect it with the pre-determined local printing path; for non-load-bearing walls, make a Z-shaped printing path that follows the outer contour and has sufficient internal space; between the upper and lower layers of the printing layers in each printing area, the connecting path along the contour and the path along the diagonal web members correspond up and down, and the lower layer can support the upper layer; the end point of the adjacent lower layer printing of each printing layer in each printing area is the start point of the upper layer printing (that is, the coordinates x and y are the same), and each printing area forms a continuous printing path; S5, analyzing and optimizing the slices and path planning: performing statistics on the length of each printing layer line and the printing time, and analyzing whether the layer interval time exceeds the initial setting time of the concrete; if there are printing layers that do not meet the requirements, return to step S4 for adjustment; S6, input planning and output 3D printing program: summarize the global path planning, slicing and printing path planning results, use digital model adaptation software to compile printing code, and output the program for architectural 3D printing.

[0008] Preferably, in step S1, the digital model adaptation software includes Autodesk Revit 2018 three-dimensional architectural design software, Rhino 3D modeling design software, and Grasshopper visual programming plug-in, and the architectural model uses the FBX format.

[0009] Furthermore, the step S2 specifically includes the following steps: In the horizontal direction, different printing areas are divided according to the range that the robot arm can reach; in the vertical direction, different printing areas are divided according to the variable cross-section parts of the building model including the ground beam, ring beam, door and window openings; according to the positional relationship of each printing area, the printing order of each printing area is sorted, and the working position of the 3D printer and its extension stand is set at each stage to ensure that the position does not conflict with the printed wall.

[0010] Furthermore, the step S4 specifically includes the following steps: For load-bearing walls with a thickness of ≥200mm, make a printing path. First, move the coordinate points inward by 0.4-0.6 times the nozzle diameter from both sides of the outer contour. Then, make a truss diagonal web between the printing lines on both sides of the outer contour at an angle of 30º-60º to the center line of the wall. The printing starting point is determined as a directed line according to the one-stroke theorem, that is, the printing path of each printing layer is a figure with only even points, or a figure with only two odd points; A certain distance is kept between the diagonal web of the truss and the outer contour wall; a certain distance is kept between the later printed wall and the earlier printed wall.

[0011] Preferably, the step S4 also includes the following features: The printing path of each printing layer is a figure with only two singular points. The printing path starts from one singular point and ends at another singular point. The printing starting point of the first layer in each area is selected in the middle of the length direction of the printing wall, at the intersection of the internal truss line and the external wall line.

[0012] Preferably, in step S4: The distance between the split points on the print path curve is 0.5 times the nozzle diameter + 5mm; For load-bearing walls with a thickness of ≥200mm, a printing path is made, and a directed line is formed by moving the coordinate points inward by 0.5 times the nozzle diameter from both sides of the outer contour; Make a truss diagonal web between the printed lines on both sides of the outer contour at a 45° angle to the center line of the wall; A 20mm gap is kept between the diagonal web of the truss and the outer contour wall; a 20mm gap is kept between the later printed wall and the earlier printed wall.

[0013] Furthermore, the step S5 further includes the following steps: Statistics are collected on the length of each printing layer route and the printing time, and analysis is performed to determine whether the layer interval time exceeds the initial setting time of the concrete. If there are printing layers that do not meet the requirements, return to step S4 for adjustment. If there is a situation where the initial setting time is exceeded and it is difficult to resolve the problem by returning to step S4 to adjust the individual printing layer path planning, the mix ratio of the concrete in the printing area is adjusted to change the initial setting time so as to meet the requirements.

[0014] Preferably, the step S6 specifically includes the following steps: Export the Revit2018 model that has been detailed and designed into an FBX file, open it with Rhino software, open the visual programming Grasshopper plug-in, and use the software functions to input global path planning, slicing, and printing path planning information; for each printing area, associate the printing layers to be printed, and the software automatically finds the printing start point to generate a printing program.

[0015] Compared with the prior art, the technical solution provided by the present invention can achieve the following beneficial effects: 1. Perform global path planning before slicing and printing path planning to ensure that the printer's working radius is free of obstacles and can cover the structural stress wall, with the minimum number of printer moves; 2. The one-stroke theorem is followed in the printing path planning of printing layers, and the end point of the adjacent lower layer printing is the starting point of the upper layer printing, so as to realize continuous printing of the wall, ensure uninterrupted concrete printing, and reduce the empty travel rate; 3. A truss diagonal web printing line is set inside the wall. The printing path of the layers first goes outside the wall, and then goes along the truss diagonal web inside the wall. The printing route can avoid the print head from making sharp turns, and the amount of printing material is small; 4. Take full account of the interval time between adjacent upper and lower layers to be less than the initial setting time of the material, so that the concrete can meet the requirements of constructability and printing appearance quality before initial setting, and meet the requirements of eccentric compressive strength, stiffness and stability after final setting; 5. In the preferred solution, the printing path of each printing layer is a figure with only two singular points, and the printing path starts from one singular point and ends at another singular point; the printing starting point of the first layer in each area is selected in the middle of the length direction of the printed wall, at the intersection of the internal truss line and the external wall line, so that the connecting curve between the starting point and the ending point is the shortest on the same printing layer, and at the same time, the vertical upper side of the lower layer printing ending point is the upper layer printing starting point, and a single printing area obtains the optimal printing path, so as to shorten the printing time and reduce the material waste as much as possible while improving the printing quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the main steps of the present invention; Figure 2 It is an elevation view of the building of the embodiment; Figure 3 A top view of the building of the embodiment; Figure 4 This is a schematic diagram of the global path planning of the building in the embodiment; Figure 5 This is a schematic diagram of the slice of the printing area of ​​Building A1 of the embodiment; Figure 6 This is a schematic diagram of the A2 printing area slice of the example building; Figure 7 This is a schematic diagram of the A3 printing area slice of the embodiment; Figure 8 This is a schematic diagram of the slice of the printing area of ​​Building B1 in the embodiment; Fig. 9 This is a schematic diagram of the slice of the printing area of ​​Building B2 in the embodiment; Fig.10 This is a schematic diagram of the slice of the printing area of ​​Building B3 in the embodiment; Fig.11 This is a schematic diagram of the slice of the B4 printing area of ​​the example building; Fig.12 This is a schematic diagram of a single floor and inter-floor paths of an example building; Fig.13 for Figure 7Middle M partial enlarged view; Fig.14 This is a schematic diagram of the printing path planning for the A1-1 floor of the building in the embodiment; Fig.15 This is a schematic diagram of the printing path planning for the A1-3 floors of the building in the embodiment; Fig.16 This is a schematic diagram of the printing path planning for the A3-1 floor of the building in the embodiment; Fig.17 This is a schematic diagram of the printing path planning for the B2-4 floors of the building in the embodiment; Fig.18 This is a schematic diagram of the printing path planning for the B4-2 floor of the building in the embodiment; Fig.19 This is a schematic diagram of the printing method of structural columns; Fig. 20 Schematic diagram of cavity printing method.

[0017] Notes in the figure: 1. Equipped with reinforced steel columns. DETAILED DESCRIPTION

[0018] The technical solution of the present invention is described in detail below with reference to the accompanying drawings, and specific embodiments are provided.

[0019] See also Figure 1 The present invention discloses a practical slicing and path planning method for 3D printing large-scale buildings, comprising the following steps: S1, prepare the building model, 3D printing equipment and digital model adaptation software: complete the in-depth design of the building design digital model, reserve and embed cable ducts for water and electricity pipes; select the 3D printing equipment and robot arm model according to the plane and facade dimensions of the project; import the building design digital model into the digital model adaptation software; S2, global path planning for the building model: global path planning is performed for the building model in the horizontal and vertical directions to avoid obstacles, and the printing area is divided. The machine position setting in each area must meet the working radius range of the robot arm, and the printing order is determined according to the position relationship of each printing area; S3, slicing each printing area: the number of slices = the printing height of a printing area / the printing layer thickness, the printing layer thickness is less than 1 / 2 the nozzle diameter; the printing order of each printing layer is determined from bottom to top according to the slices; S4, plan the printing path for each printing layer: for wall positions with specific requirements including reinforced columns and segmented printing joints, first determine the local printing path; for load-bearing walls with a thickness of ≥200mm, make a printing path that first follows the outer contour of the wall and then follows the diagonal web members of the trusses inside the wall, and connect it with the pre-determined local printing path; for non-load-bearing walls, make a Z-shaped printing path that follows the outer contour and has sufficient internal space; between the upper and lower layers of the printing layers in each printing area, the connecting path along the contour and the path along the diagonal web members correspond up and down, and the lower layer can support the upper layer; the end point of the adjacent lower layer printing of each printing layer in each printing area is the start point of the upper layer printing (that is, the coordinates x and y are the same), and each printing area forms a continuous printing path; S5, analyzing and optimizing the slices and path planning: performing statistics on the length of each printing layer line and the printing time, and analyzing whether the layer interval time exceeds the initial setting time of the concrete; if there are printing layers that do not meet the requirements, return to step S4 for adjustment; S6, input planning and output 3D printing program: summarize the global path planning, slicing and printing path planning results, use digital model adaptation software to compile printing code, and output the program for architectural 3D printing.

[0020] The following provides specific embodiments of the present invention. Figure 2 , Figure 3 , Figure 4 The building elevation, top view and stereogram of a certain project with a construction area of ​​about 130 square meters is a public service city station integrating public toilets, management rooms, sanitation homes and other functions. It is designed to be built using 3D printing technology. The printed wall heights are 2.2m, 2.8m and 3.2m, the load-bearing wall thickness is 200mm, and the building width is 6.79m.

[0021] The practical slicing and path planning method for 3D printing large-scale buildings of the present invention is applied, and steps S1-6 are performed in sequence: Step S1: Use Autodesk Revit 2018 3D architectural design software to complete the in-depth design of the building design digital model, reserve pre-buried cable ducts for water and electricity pipes; export the building model file in FBX format, import it into Rhino 3D modeling design software, open the Grasshopper visual programming plug-in, and select the 3D printing equipment and robot arm model according to the project plane and facade dimensions. The robot arm model for this project is KR210 R2700-2.

[0022] Step S2: According to the 3D printing equipment and robot arm model, determine the robot arm working radius and the print head diameter to obtain the printable space size range. In the horizontal direction, the different printing areas are divided according to the range that the robot arm can reach; in the vertical direction, the different printing areas are divided according to the variable cross-section parts of the building model including the ground beam, ring beam, door and window openings; according to the position relationship of each printing area, the printing order of each printing area is sorted, and the working position of the 3D printer and its extension frame at each stage is set to ensure that the position does not conflict with the printed wall. See Figure 4 , this project is divided into 8 blocks horizontally: A1, A2, A3, A4, B1, B2, B3, B4, see Figure 5-11 , and divided them in the vertical direction, a total of 60 printing areas are obtained, including A1-1~A-17, A2-1~A2-2, A3-1~A3-12, A4-1~A4-2, B1-1~B-9, B2-1~B2-7, B3-1~B3-4, B4-1~B4-7, and the order of printing in the horizontal direction is determined as: A1, A2, A4, A3; B1, B3, B2, B4; the vertical direction is printing from bottom to top for each block.

[0023] Step S3: Slice the inner and outer walls that have been determined to be printed in sequence. The number of slices = the printing height of a certain printing area / the printing layer thickness. The printing layer thickness is 1 / 2 the nozzle diameter. The printing order of each printing layer is determined from bottom to top according to the slices. With the help of software operation, select the projection curve or control point, equidistant section line for slicing, select the slicing direction, equidistant section line spacing, and automatically generate the slice layer. The lines of each layer are composed of the coordinates of the equally divided points. After slicing of this project, the printing layer situation of each printing area can be seen in Figure 5-11 , as well as the single-layer line length and printing schedule of each printing area in the following text.

[0024] Step S4: Plan the printing path for each printing layer. The connection path along the contour and the path along the diagonal brace between the upper and lower layers of the printing layer in each printing area correspond to each other, and the lower layer can support the upper layer. The end point of the printing of the adjacent lower layer of each printing layer in each printing area is the start point of the printing of the upper layer (that is, the coordinates x and y are the same), and each printing area forms a continuous printing path. Fig.12 , the starting point of the nth layer printing is S n , the end point is E n , the starting point of the n+1th layer printing is S n+1 , the end point is E n+1 , E n With E n+1 The coordinates x and y are the same, and the continuous printing path of the nth layer and the n+1th layer is S n —E n —En+1 —S n+1 , and so on for each printing layer in the same printing area.

[0025] Specifically for the printing path within each printing layer, first determine the local printing path for the wall position with specific requirements, including the reinforced column and the segmented printing joint, see Fig.14 For the reinforced steel column 1, these positions need to determine the square path first, so that a square space can be left when printing, and then filled after printing to form a structural column.

[0026] Figure 14-18 Schematic diagrams of printing path planning for the A1-1 layer, A1-3 layer, A3-1 layer, B2-4 layer, and B4-2 layer of the building in the example are respectively shown. The printing starting point directed line is determined according to the one-stroke theorem. The printing path of each printing layer is a figure with only two singular points. The printing path starts from one singular point and ends at another singular point.

[0027] See also Fig.14 , 15 17. For the load-bearing wall with a thickness of ≥200mm, make a printing path. First, move the coordinate points inward by 0.5 times the nozzle diameter from both sides of the outer contour and connect them with the predetermined local printing path. Then, make a truss diagonal web between the printing lines on both sides of the outer contour at an angle of 30º-60º to the center line of the wall. See also Fig.16 , 18 For non-load-bearing walls, follow the outer contour and make a Z-shaped printing path if there is enough internal space.

[0028] The printing start point of the first layer of each area is selected in the middle of the length direction of the printed wall, at the intersection of the internal truss line and the external wall line. Fig.14 Schematic diagram of the printing path planning of the A1-1 layer, the printing start point is S A1-1 , the end point is E A1-1 , print start point S A1-1 Select the intersection of the interior truss line and the exterior wall line in the middle of the length of the printed wall. Fig.13 , print start point S n Midway along the length of the printed wall, at the intersection of the interior truss lines and the exterior wall lines.

[0029] See also Fig.19 The spacing h1 between the post-printing wall indicated by the dotted line and the pre-printing wall indicated by the solid line is 20 mm.

[0030] See also Fig. 20, the distance h2 between the split points on the printing path curve is 0.5 times the nozzle diameter + 5mm; the spacing h3 reserved between the truss diagonal web and the outer contour wall is 20mm; the angle θ / 2 between the truss diagonal web and the center line of the wall is preferably 45º.

[0031] Step S5: Statistical analysis of the line length and printing time of each printing layer is performed as follows: A1 single layer line length and printing time A2 single layer line length and printing time (same as A4) ; A3 single layer line length and printing time ; B1 single layer line length and printing time ; B2 single layer line length and printing time ; B3 single layer line length and printing time ; B4 single layer line length and printing time ; Analyze whether the interval time between layers exceeds the initial setting time of concrete; if there are printing layers that do not meet the requirements, return to step S4 for adjustment; if there is a situation where it is difficult to solve the problem of exceeding the initial setting time by returning to step S4 to adjust the individual printing layer path planning, then the mix ratio of the concrete in the printing area is changed to change the initial setting time so as to meet the requirements.

[0032] In this project, based on a layer thickness of 15 mm and an estimated printer speed of 0.15 m / s, the printing time for each printing layer is less than 30 min (1800 s), meeting the requirement of not exceeding the initial setting time of concrete.

[0033] Step S6: Summarize the results of global path planning, slicing and printing path planning, use digital model adaptation software to compile printing code, and output the program for architectural 3D printing. Use Rhino software and visual programming Grasshopper plug-in to summarize the global path planning, slicing and printing path planning information, associate each printing area with the printing layer to be printed, and the operating software automatically finds the printing start point to generate the printing program.

[0034] This project applies the slicing and path planning method for 3D printing large-scale buildings of the present invention, which meets the requirements that the printer's working radius is free of obstacles and can cover the structural load-bearing walls, the printer moves at a minimum number of times, the structural load-bearing walls are continuously printed, the end point of the adjacent lower layer printing is the start point of the upper layer printing, the interval time between adjacent upper and lower layers is less than the initial setting of the material, and the number of interfaces between the printed strips is the minimum, so as to achieve continuous printing of the wall, ensure uninterrupted concrete printing, reduce the idling rate, avoid sharp turns of the print head, and use a small amount of printing material, so that the concrete meets the constructability and printing appearance quality before initial setting, and meets the eccentric compressive strength, stiffness and stability after final setting.

[0035] The above description is only a preferred example of the present invention and is not any formal or substantial limitation to the present invention. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. Any equivalent changes and modifications made to the above examples based on the essential technology of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A practical slicing and path planning method for 3D printing large-scale buildings, characterized in that: The steps include: S1, prepare the building model, 3D printing equipment and digital model adaptation software: complete the in-depth design of the building design digital model, reserve and embed cable ducts for water and electricity pipes; select the 3D printing equipment and robot arm model according to the plane and facade dimensions of the project; import the building design digital model into the digital model adaptation software; S2, global path planning for the building model: global path planning is performed for the building model in the horizontal and vertical directions to avoid obstacles, and the printing area is divided. The machine position setting in each area must meet the working radius range of the robot arm, and the printing order is determined according to the position relationship of each printing area; S3, slice each printing area: the number of slices = the printing height of a printing area / the printing layer thickness, the printing layer thickness is less than 1 / 2 the nozzle diameter; Determine the printing order of each printing layer from bottom to top according to the slices; S4, planning the printing path for each printing layer: for wall positions with specific requirements including reinforced columns and segmented printing joints, first determine the local printing path; for load-bearing walls with a thickness of ≥200mm, make a printing path that first follows the outer contour of the wall and then follows the diagonal web members of the trusses inside the wall, and connect it with the pre-determined local printing path; for non-load-bearing walls, make a Z-shaped printing path that follows the outer contour and has sufficient internal space; between the upper and lower layers of the printing layers of each printing area, the connecting path along the contour and the path along the diagonal web members correspond up and down, and the lower layer can support the upper layer; the end point of the printing of the adjacent lower layer of each printing layer in each printing area is the start point of the printing of the upper layer, and each printing area forms a continuous printing path; S5, analyzing and optimizing the slicing and path planning: performing statistics on the length of each printing layer line and the printing time, and analyzing whether the layer interval time exceeds the initial setting time of the concrete; If there are printing layers that do not meet the requirements, return to step S4 for adjustment; S6, input planning and output 3D printing program: summarize the global path planning, slicing and printing path planning results, use digital model adaptation software to compile printing code, and output the program for architectural 3D printing.

2. The practical slicing and path planning method for 3D printing large-scale buildings according to claim 1 is characterized in that: In step S1, the digital model adaptation software includes Autodesk Revit 2018 3D architectural design software, Rhino 3D modeling design software, and Grasshopper visual programming plug-in, and the architectural model uses the FBX format.

3. The practical slicing and path planning method for 3D printing large-scale buildings according to claim 1 is characterized in that: The step S2 specifically includes the following steps: In the horizontal direction, different printing areas are divided according to the range that the robot arm can reach; in the vertical direction, different printing areas are divided according to the variable cross-section parts of the building model including the ground beam, ring beam, door and window openings; according to the positional relationship of each printing area, the printing order of each printing area is sorted, and the working position of the 3D printer and its extension stand is set at each stage to ensure that the position does not conflict with the printed wall.

4. The practical slicing and path planning method for 3D printing large-scale buildings according to claim 1, characterized in that: The step S4 specifically includes the following steps: For load-bearing walls with a thickness of ≥200mm, make a printing path. First, move the coordinate points inward by 0.4-0.6 times the nozzle diameter from both sides of the outer contour. Then, make a truss diagonal web between the printing lines on both sides of the outer contour at an angle of 30º-60º to the center line of the wall. The printing starting point is determined as a directed line according to the one-stroke theorem, that is, the printing path of each printing layer is a figure with only even points, or a figure with only two odd points; A certain distance is kept between the diagonal web of the truss and the outer contour wall; a certain distance is kept between the later printed wall and the earlier printed wall.

5. The practical slicing and path planning method for 3D printing large-scale buildings according to claim 4, characterized in that: In step S4, the printing path of each printing layer is a figure with only two singular points, and the printing path starts from one singular point and ends at another singular point; the printing starting point position of the first layer in each area is selected in the middle of the length direction of the printed wall, at the intersection of the internal truss line and the external wall line.

6. The practical slicing and path planning method for 3D printing large-scale buildings according to claim 5, characterized in that: In the step S4, The distance between the split points on the print path curve is 0.5 times the nozzle diameter + 5mm; For load-bearing walls with a thickness of ≥200mm, a printing path is made, and a directed line is formed by moving the coordinate points inward by 0.5 times the nozzle diameter from both sides of the outer contour; Make a truss diagonal web between the printed lines on both sides of the outer contour at a 45° angle to the center line of the wall; A 20mm gap is kept between the diagonal web of the truss and the outer contour wall; a 20mm gap is kept between the later printed wall and the earlier printed wall.

7. The practical slicing and path planning method for 3D printing large-scale buildings according to claim 1, characterized in that: The step S5 further comprises the following steps: Statistics are collected on the length of each printing layer route and the printing time, and analysis is performed to determine whether the layer interval time exceeds the initial setting time of the concrete. If there are printing layers that do not meet the requirements, return to step S4 for adjustment. If there is a situation where the initial setting time is exceeded and it is difficult to resolve the problem by returning to step S4 to adjust the individual printing layer path planning, the mix ratio of the concrete in the printing area is adjusted to change the initial setting time so as to meet the requirements.

8. The practical slicing and path planning method for 3D printing large-scale buildings according to claim 1, characterized in that: The step S6 specifically includes the following steps: Export the Revit2018 model that has been detailed and designed to an FBX file, open it with Rhino software, open the visual programming Grasshopper plug-in, and use the software functions to input global path planning, slicing, and printing path planning information; For each printing area, the printing layer to be printed is associated, and the software automatically finds the printing start point and generates the printing program.

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