A 3D concrete printing path planning method for realizing an inclined top surface

Abstract

The present invention provides a 3D concrete printing path planning method for implementing an inclined top surface, including: constructing a three-dimensional digital model of a concrete building component for 3D printing; performing equally spaced gradient slicing between the top surface and the bottom surface of the three-dimensional digital model to obtain a gradient integral layer variable plane of the entire three-dimensional digital model; vertically dividing the three-dimensional digital model along the Z-axis to obtain k + 2 slicing lines, and each of the integral layer variable planes is divided into k + 1 ranges by the slicing lines; adding a sliced sandwich layer between every two integral layer variable planes, and the sandwich layer is located in k of the ranges close to the highest point side of the three-dimensional digital model; taking the path obtained after the first slicing and the second slicing as the 3D concrete printing path. The present invention can effectively avoid the situations of insecure interlayer bonding and interlayer misalignment, and at the same time make the height distribution of each layer of concrete printing material in the 3D printing process more reasonable, the transition more uniform, and the printing finished product effect better.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing concrete, and particularly relates to a printing path planning method for 3D printing of concrete with complex shapes, specifically for realizing the planning of 3D concrete printing paths for inclined top surfaces. Background Art

[0002] A relatively common printing path planning method in the field of 3D printing concrete is the contour machining process (US5529471A), that is, the horizontal layer-by-layer printing method. That is, the three-dimensional model of the building is sliced by the method of equidistant layering, transformed into a printing path of layer-by-layer stacking, and then the printing device (such as a robotic arm, a gantry printer) is made to move along the printing path and the printing material is evenly extruded through a pumping system, thereby realizing the shaping of the concrete. However, with the increasing demand for concrete shapes in the construction field, the horizontal layer-by-layer printing method can no longer meet the forming requirements of all concrete shapes.

[0003] The horizontal layer-by-layer printing method can realize the printing of shapes with relatively gentle top surfaces, but cannot process concrete shapes with large inclined top surfaces. This is because after the inclined surface is horizontally layered, "sawteeth" of the layering will be exposed on the top surface, resulting in a poor overall effect. At the same time, for inclined surfaces with a large inclination, horizontal layering will cause the position of each layer of printing lines to change violently when cutting to the inclined surface, resulting in a situation where the overhang of the printing material between the upper and lower layers is too large or even completely separated. The technical problem that the present invention aims to solve is the problem of generating printing paths for concrete building components with inclined surfaces on the top surface.

[0004] Therefore, how to provide a printing path planning method that makes the height distribution of each layer of concrete printing material more reasonable and the transition more uniform during the 3D printing of concrete building components with inclined surfaces on the top surface is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention can solve the problem of generating printing paths for concrete building components with inclined surfaces on the top surface. It can effectively avoid the situation of insecure interlayer bonding and interlayer misalignment, and at the same time make the height distribution of each layer of concrete printing material during the 3D printing process more reasonable, the transition more uniform, and the printing finished product effect better.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for realizing the 3D concrete printing path planning of an inclined top surface, comprising the following steps;

[0008] S1. Construct a three-dimensional digital model for 3D printing of concrete building components;

[0009] S2. Primary segmentation: Perform equally spaced gradient segmentation between the top surface and the bottom surface of the three-dimensional digital model to obtain a gradient integral layer variable plane of the entire three-dimensional digital model;

[0010] S3. Vertically divide the three-dimensional digital model along the Z-axis to obtain k + 2 cutting lines, and each of the integral layer variable planes is divided into k + 1 ranges by the cutting lines;

[0011] S4. Secondary segmentation: Add a segmented interlayer between every two integral layer variable planes, and the interlayer is located in k of the ranges on the side close to the highest point of the three-dimensional digital model, where k ∈ N+;

[0012] S5. Take the path obtained after the primary segmentation and the secondary segmentation as the 3D concrete printing path.

[0013] Preferably, before the S2, it further includes: judging whether the three-dimensional digital model is applicable to the S2-S4 layering method: judging whether there is one or more inclined planes on the top surface of the model, and whether the model can be cut into two or more segments with regular plane changes along the vertical plane direction. If so, enter S2.

[0014] Preferably, the S2 includes:

[0015] Extract the lowest point A and the highest point B on the top surface of the three-dimensional digital model, and calculate the elevation H of the lowest point min 、the elevation H of the highest point max and the horizontal distance d between the two points AB ;

[0016] Judge the elevation H of the lowest point min and the elevation H of the highest point max Whether the relationship between the distance and the horizontal distance d AB meets the preset conditions. If so, perform equally spaced gradient segmentation on the three-dimensional digital model and enter S3.

[0017] Preferably, the preset conditions include: judging d AB ≥H max -H min If so, perform equally spaced gradient segmentation on the three-dimensional digital model and enter S3.

[0018] Preferably, the steps of the equally spaced gradient segmentation in the S2 include:

[0019] According to the lowest target height h of each layer of the 3D printed concrete min , through the formula n = int(H min / h min) + 1 calculates the variable planes for completely slicing the entire three-dimensional digital model, obtaining a total of n variable planes, and getting n - 2 groups of gradually changing integral layer variable planes among the two variable planes. This approach is to ensure that sufficient interlayer space can be reserved at the lowest part of the model during slicing, which can effectively avoid material accumulation caused by too small layer height during the printing process.

[0020] Preferably, judge the elevation H of the lowest point min and the elevation H of the highest point max The relationship between the distance and the horizontal distance d AB After meeting the preset conditions, calculate a = H max / H min , and make a conditional judgment If a ≥ 1.5, if the result is yes, perform equally spaced gradient slicing on the three-dimensional digital model and enter S3.

[0021] Preferably, the method for determining the number of interlayers between adjacent integral layer variable planes includes:

[0022] If a ∈ S k , satisfying S k =(k + 0.5, k + 1.5], where the maximum value that k can take is the number of additional interlayers between adjacent integral layer variable planes;

[0023] a = H max / H min , H min is the elevation of the lowest point of the three-dimensional digital model, and H max is the elevation of the highest point.

[0024] The reasonable selection of the number of interlayers is beneficial to ensuring a more appropriate number of slices at the highest part of the model and avoiding the situation of insufficient material supply due to too large interlayer height.

[0025] Preferably, the method for dividing into k + 1 ranges in S3 includes:

[0026] Vertically and equally divide the three-dimensional digital model along a plane parallel to the Z-axis, and mark them as cutting lines A,..., cutting line i,..., cutting line k, cutting line B respectively. The lowest point on the top surface of the three-dimensional digital model is A, and the highest point is B;

[0027] The plane range obtained by dividing between cutting line i and cutting line B is range i.

[0028] Preferably, in S4: The method for determining the interlayer position between every two adjacent integral layer variable planes includes:

[0029] Calculate the maximum interlayer height h between integral layer variable planes max = H max / (n - 1), shift all the integral layers to the plane downward in the normal direction k times, and the offset distance each time is m = h max / (k + 1), and sequentially label the offset intermediate layers as intermediate layer 1, ……, intermediate layer i, ……, intermediate layer k according to the offset order, so as to determine the slicing positions of each type of intermediate layer; n is the sum of the number of the top surface, bottom surface and integral layer planes of the three-dimensional digital model;

[0030] Take the spatial intersection of the range i and the intermediate layer i, determine the form of the intermediate layer slice corresponding to the spatial intersection, and use the intermediate layer slice to perform secondary slicing on the three-dimensional digital model, and take the obtained path after cutting.

[0031] The reason for choosing to offset the variable plane in the normal direction instead of directly generating a new set of variable planes between the variable planes is that the normal offset can maximize the guarantee that the distance between the integral layer plane and the intermediate layer remains constant during printing, improving the stability of the printing process.

[0032] Preferably, S5 includes: sorting the elevation of the highest points of all the extracted paths, sequentially connecting all the slice paths from low to high, and the connection positions of the paths are the highest point positions of each path, and then obtaining a continuous printing path. The reason for choosing the highest point position for path connection is that after the intermediate layer is segmented, the lowest point position of each layer slice has changed and cannot correspond to the same plane position, while their highest point positions always remain unchanged, so it is most suitable for path connection.

[0033] It can be seen from the above technical solutions that compared with the prior art, the beneficial effects of the present invention include:

[0034] In the existing 3D printing concrete forming technology, there is no case of variable plane stratification for concrete building components with large height differences, nor is there a study on adding intermediate layers between variable planes. The present invention provides a solution to this limitation. By adding intermediate layers between variable planes with large height differences and using a slice generation method to calculate the number of intermediate layers based on the height difference, the feasibility of 3D printing concrete technology for realizing inclined and curved shapes is improved, and at the same time, the printing accuracy and stability of such concrete shapes are also improved. The specific technical effects are reflected in the following aspects:

[0035] 1. With the aid of computer-aided design software and visual programming languages, the present invention determines the planar segmentation range of the mezzanine through the horizontal spatial relationship between the highest point and the lowest point of the model, determines the number and height of the mezzanine through the vertical spatial relationship between two points, and also uses pole data to judge whether the 3D model is suitable for horizontal layer-by-layer printing, variable plane printing or inserting mezzanine printing methods for slicing. This effectively associates the actual size of the model with the generation logic of the printing path, reduces the complicated process of manually judging the printing method and calculating the position of the mezzanine, and improves the intelligence of generating the 3D concrete printing path.

[0036] 2. By inserting a mezzanine into large height difference building components, the problems of material accumulation caused by too dense printing lines at the lower part and insufficient material supply caused by too sparse printing lines at the higher part during the printing process of large height difference concrete building components are solved.

[0037] 3. The present invention locates the newly inserted mezzanine by offsetting the entire layer in the normal direction of the variable plane. This method can minimize the sudden change in height difference during the switching between the mezzanine and the entire layer, and maximize the guarantee of a constant height difference between the entire layer and the mezzanine, thus improving the printing quality of building components.

[0038] 4. The present invention first slices the model with the entire layer variable plane and then inserts a mezzanine into the entire layer, which meets the requirement that the printing path needs to be entire layer printing on the top surface and ensures the stable effect of the top surface treatment of concrete components. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] 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 the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts;

[0040] Figure 1 It is a flowchart of a method for planning a 3D concrete printing path for realizing an inclined top surface provided for an example of the present invention;

[0041] Figure 2 It is a simulation diagram of adding one mezzanine between adjacent variable planes provided for Embodiment 1 of the present invention;

[0042] Figure 3 It is a simulation diagram of adding two mezzanines between adjacent variable planes provided for Embodiment 2 of the present invention;

[0043] Figure 4 It is a simulation diagram of adding three mezzanines between adjacent variable planes provided for Embodiment 3 of the present invention;

[0044] Figure 5 This is a simulation diagram of a sandwich structure arranged in a 3D concrete structure with two inclined planes at the top provided in the fourth embodiment of the present invention. Specific implementation manners

[0045] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0046] The present invention is applicable to 3D printed concrete building components with inclined planes at the top and not suitable for slicing by the horizontal layer-by-layer printing method. Here, the horizontal layer-by-layer printing refers to slicing and printing the three-dimensional digital model layer by layer along the XY horizontal plane in the XYZ coordinate system of the three-dimensional digital model.

[0047] The present invention provides a method for real-time trajectory planning of autonomous driving vehicles at signal-controlled intersections in a mixed environment of manual and autonomous driving, including the following steps:

[0048] S1. Construct a three-dimensional digital model for 3D printed concrete building components;

[0049] S2. Primary slicing: Perform equally spaced gradient slicing between the top surface and the bottom surface of the three-dimensional digital model to obtain a gradient whole-layer variable plane of the entire three-dimensional digital model;

[0050] S3. Vertically divide the three-dimensional digital model along the Z axis to obtain k + 2 slicing lines, and each of the whole-layer variable planes is divided into k + 1 ranges by the slicing lines;

[0051] S4. Secondary slicing: Add sliced sandwich layers between every two whole-layer variable planes, and the sandwich layers are located in k of the ranges close to the highest point side of the three-dimensional digital model, where k ∈ N+;

[0052] S5. Take the path obtained after the primary slicing and the secondary slicing as the 3D concrete printing path.

[0053] It should be noted that each whole-layer variable plane obtained by equally spaced gradient slicing, and the added sliced sandwich layers are all slicing planes with an inclined angle relative to the bottom surface of the three-dimensional digital model.

[0054] As Figure 1 shown, the specific execution process of the above steps includes:

[0055] Step 1. In one embodiment, use computer-aided design software to establish a digital model of a concrete building component for 3D printing.

[0056] Step 2. In one embodiment, determine whether the digital model is applicable to the interlayer stratification method according to the following criteria:

[0057] (1) One or more inclined planes are provided on the top surface of the model;

[0058] (2) The model can be cut into two or more segments with regular plane changes along the vertical plane direction.

[0059] If the above criteria are met, the model information can be further extracted;

[0060] Step 3. In one embodiment, use computer-aided design software to extract the lowest point A and the highest point B on the top surface of the digital model, and calculate the elevation H of the lowest point min , the elevation H max of the highest point and the horizontal distance d AB between the two points, and save the data for future use;

[0061] Step 4. In one embodiment, make a conditional judgment If d AB ≥H max -H min .

[0062] If the result is yes, it indicates that the inclination of the top surface of the model is relatively gentle and still within the slope range suitable for the inclined stacking of concrete materials. Therefore, it is considered that the model is suitable for continuing to use the interlayer printing method proposed by the present invention, and the process enters Step 5-1;

[0063] If the result is no, it is considered that the inclination of the top surface of the model is relatively large. Even if interlayer printing is used, the top layer may collapse due to excessive inclination, and such models are instead suitable for the method of horizontal layer-by-layer printing. The model is equally spaced and cut horizontally, and the inclined surface is printed by means of overhanging layer by layer. For this method, only the paths after slicing need to be sorted in ascending order of the Z-axis height of the plane where they are located and then connected in series, and the process can directly jump to Step 12;

[0064] Step 5-1. In one embodiment, according to the lowest target height h min (the applicable value range is 6 mm - 8 mm according to the size and shape of the building component), calculate the number n of variable plane (including the top surface, the whole layer variable plane and the bottom surface) slices for completely dividing the entire three-dimensional model through the formula n = int(H min / h min ) + 1, and save the data for future use. This approach is to ensure that a sufficiently large interlayer space can be reserved at the lowest part of the model for the slices, which can effectively avoid material accumulation caused by too small layer height during the printing process;

[0065] Step 5-2: In one embodiment, the top plane and the bottom plane of the three-dimensional model are extracted using the visual programming language Grasshopper based on the Rhino platform, and (n - 2) sets of gradually changing integral variable planes are generated in the two planes. The model is completely sliced using these n planes, and the paths obtained after slicing are reserved for later use;

[0066] Step 6: In one embodiment, calculate a = H max / H min , and make a conditional judgment If a ≥ 1.5. If the result is yes, it indicates that the ratio of the highest point to the lowest point of the model is relatively large, and the method of inserting interlayers for printing is suitable. The process proceeds to Step 7. If the result is no, it means that the ratio of the highest point to the lowest point of the model is relatively small, and high-quality printing can be achieved through the variable plane slicing method without the need to insert additional interlayers. Therefore, as long as the slicing paths in Step 5-2 are sorted in ascending order of the Z-axis height of the highest point of each layer path and the paths are concatenated, the process can jump to Step 12;

[0067] Step 7: In one embodiment, determine the number of interlayers between adjacent integral variable planes. If a ∈ (1.5, 2.5], it is recommended to add one interlayer between adjacent variable planes. If a ∈ (2.5, 3.5], it is recommended to add two interlayers, and so on. If a ∈ S k , S k =(k + 0.5, k + 1.5], then add k interlayers (k ∈ N+). The reasonable selection of the number of interlayers is beneficial to ensuring that the model obtains a more appropriate number of slices at the highest point and avoiding the situation of insufficient material supply due to excessive layer height;

[0068] Step 8-1: In one embodiment, according to the number of interlayers k determined in Step 5, divide the line segment AB into k + 1 segments, and draw vertical lines at each segmentation point in the top plane as the cutting lines for dividing the model plane. They are respectively marked as cutting line A, cutting line 1, cutting line 2,..., cutting line k, cutting line B along the ray AB direction to determine the slicing range of each type of interlayer;

[0069] Step 8-2: In one embodiment, according to Step 8-1, define the plane range between cutting line 1 and cutting line B as range 1 (that is, cut the model vertically along the Z-axis direction with cutting line 1, and keep the part close to cutting line B after cutting as range 1), define the plane range between cutting line 2 and cutting line B as range 2, and so on. Define the plane range between cutting line k and cutting line B as range k;

[0070] Step 9. In one embodiment, according to the number of interlayers k determined in Step 5, determine the positions of the interlayers between every two adjacent integral layer change planes. The specific method is as follows: Calculate the maximum interlayer height h between the integral layer change planes max = H max / (n - 1), and offset all the integral layer change planes except the bottom surface of the model downward k times in the direction of their normal vectors. The offset distance each time is m = h max / (k + 1). According to the offset sequence, label the offset interlayer planes as Interlayer 1, Interlayer 2, ……, Interlayer k in turn, so as to determine the slicing positions of each type of interlayer. The reason for choosing to offset the change planes in the direction of the normal vector instead of directly generating a new set of change planes between the change planes is that normal offset can maximize the guarantee that the distance between the integral layer change planes and the interlayers remains constant during printing, improving the stability of the printing process;

[0071] Step 10. In one embodiment, take the spatial intersection of Range 1 and Interlayer 1, the spatial intersection of Range 2 and Interlayer 2, ……, the spatial intersection of Range k and Interlayer k to determine the morphological forms of all interlayer slices, and use these interlayer slices to perform secondary cutting on the 3D model, and take the obtained paths after cutting for standby;

[0072] Step 11. In one embodiment, sort the highest point elevations of all the paths extracted in Step 5-2 and Step 10, and offset the sorted paths inward along the planes where they are located. The offset distance is b / 2, (b is the printing width required for 3D printing concrete components, and the applicable value range is 30mm - 60mm according to the size and shape of building components), and then connect all the slice paths in sequence from low to high. The connection positions of the paths are the highest point positions of each path, and then a continuous printing path is obtained. The reason for choosing the highest point position for path connection is that after the interlayer segmentation, the lowest point positions of each layer of slices have changed and cannot correspond to the same plane position, while their highest point positions always remain unchanged, so they are most suitable for path connection;

[0073] Step 12. In one embodiment, use the method of equal-distance breakpoints to divide the printing path into continuous positioning points;

[0074] Step 13. In one embodiment, use the normal vector direction at the corresponding position in the plane where each positioning point is located as the Z direction, and the vector direction of the projection of ray AB in each plane as the Y direction to generate the three-dimensional rectangular coordinates of each point, so as to determine the initial coordinate positions of the robotic arm at each point position. This step is beneficial to ensuring that the robotic arm can run along the plane where each layer of slices is located during movement, thus ensuring the printing quality;

[0075] Step 12. In one embodiment, in a visual programming language, according to different printing environments and robotic arm models, the initial coordinate positions at each positioning point are adjusted to meet the spatial limitations of the robotic arm's operation, and then G-code (G-code) for 3D printing is generated in combination with the operating parameters of the robotic arm.

[0076] The following presents an embodiment of the path planning of the method of the present invention in the specific 3D digital model printing of concrete.

[0077] Embodiment 1: Schematic illustration of adding a sandwich layer between adjacent variable planes

[0078] See Appendix Figure 2 , this embodiment is a cylindrical concrete flowerpot with an inclined top surface. Its model structure is relatively simple, and the ratio of the highest elevation to the lowest elevation of the top surface is 2:1. Therefore, the generation of the printing path of the flowerpot can be achieved by adding a sandwich layer between adjacent variable planes. Figure 2 a- Figure 2 e shows the layering process of the flowerpot model. The steps of its path generation can all be implemented according to the process described above, where the value of a is 2 and the value of k is 1.

[0079] Figure 2 a shows the overall shape of Embodiment 1. Figure 2 b shows the top and bottom planes of the extracted 3D model. Figure 2 c shows the generation of uniformly varying full-layer variable plane slices between the top plane and the bottom plane. Figure 2 d shows the insertion of sandwich slices according to the spatial positions calculated in Step 8. Figure 2 e shows the geometric shape after slicing.

[0080] Embodiment 2: Schematic illustration of adding two sandwich layers between adjacent variable planes

[0081] See Appendix Figure 3 , this embodiment has a relatively gentle slope, but the overall height of the model is very low. Therefore, the ratio of the highest point to the lowest point elevation of its top surface still reaches 3:1. In addition, the text part on the topmost surface of the model is a separate protruding structure. Therefore, in this embodiment, the top surface of the pattern part is considered as the top surface of the variable plane slice. See Figure 3 shown in b, and the text part is sliced with a plane parallel to the top surface of the pattern. See Figure 3 shown in e. That is to say, an additional step needs to be added between Step 8 and Step 9 to translate the top plane of the pattern part upward along the Z-axis direction n times, where n = int(H top / m), and the distance is H top / n, where H topis the height in the Z-axis direction where the text protrudes, and m is the plane offset distance calculated in step 7. This is beneficial for ensuring that the slicing height of the text part is similar to the average slicing height of the model at the higher part. The remaining steps for path generation can all be implemented according to the process described above, where the value of a is 3 and the value of k is 2.

[0082] Figure 3 a shows the overall shape of the second embodiment. Figure 3 b shows the bottom plane of the extracted three-dimensional model and the top plane of the pattern part. Figure 3 c shows generating uniformly varying full-layer variable plane slices between the top plane and the bottom plane. Figure 3 d shows inserting sandwich slices according to the spatial position calculated in step 8. Figure 3 e shows slicing the protruding text part in the model with a plane parallel to the top surface of the pattern. Figure 3 f shows the geometric shape after slicing.

[0083] Embodiment Three: Schematic illustration of adding three sandwich layers between adjacent variable planes

[0084] See the appendix Figure 4 , the feature of this embodiment is that the slope of the top surface is relatively large, and the ratio of the elevation of the highest point to the lowest point reaches 4:1, and the side surface of the shape is an arc. If the method of cutting the model along the Z-axis with the top surface as a reference in step 6 is still used, it is impossible to evenly divide this arc-shaped side surface. Therefore, in this embodiment, it is necessary to add three groups of sandwich layers between the full-layer variable planes and change the definition method of the cutting range in step 6. Specifically, step 6 will be adjusted as follows: retain the method of determining the cutting line in step 6-1, but in step 6-2, instead of cutting the model in the Z-axis direction, each cutting line is swept along the trajectory of the arc of the side surface of the model to cut the model, as Figure 4 shown in d. This cutting method can ensure that the planes within each type of slicing range have the greatest similarity, and at the same time, the layer height of each sandwich layer can also remain constant at the lowest part. The remaining steps for path generation can all be implemented according to the process described above, where the value of a is 4 and the value of k is 3.

[0085] Figure 4 a shows the overall shape of the third embodiment. Figure 4 b shows the top and bottom planes of the extracted three-dimensional model. Figure 4 c shows generating uniformly varying full-layer variable plane slices between the top plane and the bottom plane. Figure 4 d shows sweeping the cutting line obtained in step 6-1 along the arc direction of the side surface of the model to determine the slicing range of each type of sandwich layer. Figure 4 e shows inserting sandwich slices according to the spatial position calculated in step 8. Figure 4f shows the sliced geometric shape.

[0086] Example 4: Schematic illustration of a case where the top is composed of two inclined planes

[0087] See Appendix Figure 5 , the top surface of this embodiment is composed of two inclined planes. For such models, it can be divided into two along the intersection position of the two top planes and regarded as two independent models each composed of one inclined plane. Then, the slicing steps described above are implemented, and the sliced paths are connected. In this case, the value of a is 2 and the value of k is 1. The same method is also applicable to three-dimensional models with multiple inclined planes at the top.

[0088] Figure 5 a shows the overall shape of Example 4. Figure 5 b shows the top and bottom planes of the extracted three-dimensional model. Figure 5 c shows the generation of uniformly varying whole-layer variable plane slices between the top plane and the bottom plane. Figure 5 d shows the insertion of interlayer slices according to the spatial positions calculated in step 8. Figure 5 e shows the sliced geometric shape.

[0089] The above has introduced in detail the 3D concrete printing path planning method for realizing an inclined top surface provided by the present invention. In this embodiment, specific examples are used to elaborate on 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.

[0090] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined in this embodiment can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown in this embodiment, but will conform to the widest scope consistent with the principles and novel features disclosed in this embodiment.

Claims

1. A 3D concrete printing path planning method for realizing an inclined top surface, characterized in that, It includes the following steps; S1. Construct a three-dimensional digital model of a 3D printed concrete building component; judge whether the three-dimensional digital model is applicable to the layering method of S2 - S4: judge whether the top surface of the model has one or more inclined planes, and whether the model can be cut into two or more segments with regular plane changes along the vertical plane direction. If so, enter S2; S2. Primary cutting: Perform equally spaced gradient cutting between the top surface and the bottom surface of the three-dimensional digital model to obtain a gradient whole-layer variable plane of the entire three-dimensional digital model, including: Extract the lowest point A and the highest point B on the top surface of the 3D digital model, and calculate the elevation H of the lowest point min , the elevation H of the highest point max and the horizontal distance d between the two points AB ; Judge the elevation H of the lowest point min and the elevation H of the highest point max The relationship between the distance and the horizontal distance d AB meets the preset conditions. If so, perform equally spaced gradual slicing on the three-dimensional digital model and enter S3; The steps of the equally spaced gradient cutting include: According to the minimum target height h of the printing path for each layer of 3D printed concrete min , through the formula n = int(H min / h min ), calculate the variable planes used to completely divide the entire three-dimensional digital model, obtain the total number of variable planes as n, and obtain n - 2 groups of gradually changing integral variable planes in the two variable planes; S3. Vertically divide the three-dimensional digital model along the Z-axis to obtain k + 2 cutting lines, and each of the whole-layer variable planes is divided into k + 1 ranges by the cutting lines; S4. Secondary cutting: Add an interlayer for cutting in the middle of every two adjacent whole-layer variable planes. The interlayer is located in k of the ranges on the side close to the highest point of the three-dimensional digital model, where k ∈ N+; S5. Take the path obtained after the primary cutting and the secondary cutting as the 3D concrete printing path.

2. The 3D concrete printing path planning method for implementing an inclined top surface according to claim 1, wherein, The preset conditions include: determining that d AB ≥H max -H min , if so, perform equally spaced gradient slicing on the three-dimensional digital model and proceed to S3.

3. The 3D concrete printing path planning method for realizing an inclined top surface according to claim 1, wherein, Judge the elevation H of the lowest point min and the elevation H of the highest point max The relationship between the distance and the horizontal distance d AB After meeting the preset conditions, calculate a = H max / H min , and make a conditional judgment If a ≥ 1.

5. If the result is yes, perform equally spaced gradient slicing on the three-dimensional digital model and enter S3.

4. The 3D concrete printing path planning method for realizing an inclined top surface according to claim 1, wherein The method for determining the number of interlayers between adjacent whole-layer variable planes includes: If a ∈ S k , satisfying S k =(k + 0.5, k + 1.5], where the maximum value that k can take is the number of additional interlayers between adjacent integral variable planes; a = H max / H min , H min is the elevation of the lowest point of the 3D digital model, and H max is the elevation of the highest point.

5. The 3D concrete printing path planning method for implementing an inclined top surface according to claim 4, characterized in that, The method for dividing into k + 1 ranges in S3 includes: Vertically and equally divide the three-dimensional digital model along a plane parallel to the Z-axis, and mark them as cutting line A,..., cutting line i,..., cutting line k, cutting line B. The lowest point of the top surface of the three-dimensional digital model is A, and the highest point is B; The plane range obtained by dividing between cutting line i and cutting line B is range i.

6. The 3D concrete printing path planning method for realizing an inclined top surface according to claim 5, wherein In S4: The method for determining the position of the interlayer between every two adjacent whole-layer variable planes includes: Calculate the maximum interlayer height h between the entire floors with variable planes max = H max / (n - 1). Offset all the entire floors with variable planes downward k times in their normal directions, and the offset distance each time is m = h max / (k + 1). According to the offset sequence, mark the offset mezzanine planes as Mezzanine 1, ……, Mezzanine i, ……, Mezzanine k in turn to determine the slice positions of each type of mezzanine; n is the sum of the number of the top surface, bottom surface and entire floors with variable planes of the three-dimensional digital model Take the spatial intersection of range i and interlayer i, determine the morphological form of the interlayer slice corresponding to the spatial intersection, and use the interlayer slice to perform secondary cutting on the three-dimensional digital model, and take the path obtained after cutting.

7. The 3D concrete printing path planning method for implementing an inclined top surface according to claim 1, characterized in that, S5 includes: Sort the elevation of the highest points of all the extracted paths, and sequentially connect all the slice paths from low to high. The connection position of the paths is the highest point position of each path, and then a continuous printing path is obtained.

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