CN114347212B - 3D printing shell structure-oriented path generation method and system - Google Patents
3D printing shell structure-oriented path generation method and system Download PDFInfo
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Abstract
The invention provides a path generation method and system for a 3D printing shell structure. The method comprises the steps of determining a model printing and placing posture based on shell model data; slicing the shell model with the determined printing and placing posture layer by layer, taking each correspondingly obtained continuous line segment as a node, and constructing a first graph based on the dependency of the node; combining nodes on the first graph to generate a second graph; combining the nodes on the second graph to generate a third graph; merging nodes on each third graph; for two nodes trying to be merged on two third graphs with only one path, merging the corresponding child nodes of the two nodes trying to be merged in the second graph based on the layer thickness constraint, and iterating and merging until no mergeable nodes exist in the third graphs; and planning the path by taking the shortest total connection path represented by all the nodes in the third graph after the nodes are combined as a target, calculating the connection point of each layer, generating a final printing path, and outputting a printable file.
Description
Technical Field
The invention belongs to the technical field of 3D printing, and particularly relates to a path generation method and system for a 3D printing shell structure.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
The shell structure is characterized in that a layer of thin material is only arranged on the surface of an object in the volume of the object without internal fillers, and the shell structure is widely applied to the fields of rocket engine bodies, airplane bodies, boilers in the oil and gas industry, artistic crafts and the like. Extruded ceramic printing is an efficient method of manufacturing the housing structure.
The ceramic has a plurality of excellent physical and chemical properties, such as high temperature resistance, high hardness, corrosion resistance, low density and the like, and is widely applied to various fields of buildings, chemical engineering, daily use and the like. Among them, the shell ceramic products are most widely used, such as cups, vases, tiles, etc. With the development of high and new technology industry, various novel special ceramics have been developed greatly. The traditional ceramic product forming method is to adopt different methods to make blanks into blanks with certain shapes and sizes, and the blank forming method can be divided into a plastic method, a grouting method, a pressing method and the like, but the production period is long, the manual operation is more, the labor intensity is high, the occupied area is large, and the material consumption is more. As digital manufacturing has been increasingly developed, the precision and speed of 3D printing technology, which can manufacture solid objects having highly complex geometries by inputting digital files, have been gradually increased, and as a result, ceramic 3D printing technology has received extensive attention in recent years from both academic and industrial fields. Direct Ink Writing (DIW) is an extrusion-based 3D printing technique that uses clay as a printing material and forms a desired product by layering and depositing viscous paste and firing to obtain a ceramic product.
In the 3D printing process, the continuity of the printing path plays a crucial role in the quality of the product, because the clay itself has strong adhesiveness and fluidity, a small amount of residual clay is extruded when the extrusion is suspended, which causes burrs to appear, affects the surface quality of the product, and pulls the printed part, which causes deformation of the product and even printing failure. This is particularly evident in the case structure.
The inventor finds that the existing methods are mainly divided into two types, one type does not consider the continuity of the path, generates the printing path through common software slicing, and has low quality of printing results and often fails to print. Another type of model is capable of creating a strictly continuous print path, but requires additional paths to connect the model to the support structure, requires later manual removal of the supports, is extremely difficult for the shell model, is prone to model breakage, and can affect the surface quality of the model.
Disclosure of Invention
In order to solve the technical problems in the background art, the invention provides a path generation method and system for a 3D printing shell structure, which enable a model to maintain the continuity of the path as much as possible on the premise of easy removal, and greatly improve the printing quality and the printing speed of the model.
In order to achieve the purpose, the invention adopts the following technical scheme:
a first aspect of the present invention provides a path generation method for a 3D printing case structure, including:
determining a model printing and placing posture based on the shell model data;
slicing the shell model with the determined printing and placing posture layer by layer, taking each correspondingly obtained continuous line segment as a node, and constructing a first graph based on the dependency of the node;
combining nodes on the first graph to generate a second graph based on the principle that at least two edges point to the same node or at least two edges start from the same node;
combining nodes on the second graph based on a minimum path covering principle with dependency constraints to generate a third graph;
combining nodes on each third graph based on the principle that at least two paths exist between two points; for two nodes trying to be merged on two third graphs with only one path, merging the corresponding child nodes of the two nodes trying to be merged in the second graph based on the layer thickness constraint, and iterating and merging until no mergeable nodes exist in the third graphs;
and planning the path by taking the shortest total connection path represented by all the nodes in the third graph after the nodes are combined as a target, calculating the connection point of each layer, generating a final printing path, and outputting a printable file.
As an embodiment, the process of determining the model printing pose is as follows:
searching all placing postures which accord with the support constraint based on the shell model data;
selecting the placing posture corresponding to the minimum objective function as the model printing placing posture;
wherein the objective function consists of a weighted sum of the flat region area and the support structure volume.
As an embodiment, the process of generating the third graph is:
constructing a search tree by a cluster search algorithm, wherein each node of the tree obtains a path with a set length by depth-first search, each path is used as a node, and a search range is limited by a branch-and-bound method;
after the search tree is constructed, each path from the root node to each leaf represents a solution, and the path with the minimum depth is an optimal path;
and finally, establishing a third graph correspondingly to each optimal solution, wherein each node of the third graph corresponds to one node in the optimal solution, and the edges represent the dependency relationship among the nodes.
As an embodiment, the process of merging the corresponding child nodes of the two nodes attempting to merge in the second graph based on the layer thickness constraint is:
determining the corresponding child nodes of the two nodes trying to be merged on the two third graphs with only one path in the second graph;
the child nodes are extracted to reconstruct a sub-graph in which nodes are tried to be combined two by two based on the layer thickness constraint.
As an embodiment, the process of attempting to merge two nodes based on the layer thickness constraint in this sub-graph is:
starting to connect the top sliced layer of the node positioned above with the end point at the same side of the next layer until the bottom sliced layer, and calculating two oblique lines;
when one of the two oblique lines meets the slope constraint, connecting the oblique line with the top layer of the node above and projecting the oblique line onto the surface of the model to be used as an upper boundary, and projecting the bottom slice layer of the node below onto the surface of the model to be used as a lower boundary;
and when the areas needing flattening, corresponding to the upper and lower boundaries, can be flattened successfully, the layer thickness constraint is not violated, and the areas are judged to be capable of being merged and generate the pre-path.
As an embodiment, in the process of performing path planning, the method further includes: and smoothing the total connection path characterized by all the nodes in the third graph after the nodes are merged.
A second aspect of the invention provides a path generation system for a 3D printed housing structure, comprising:
a printing and placing posture determining module for determining a model printing and placing posture based on the shell model data;
the first graph building module is used for slicing the shell model with the printing and placing posture determined layer by layer, taking each correspondingly obtained continuous line segment as a node, and building a first graph based on the dependency of the node;
the first graph node merging module is used for merging nodes on the first graph based on the principle that at least two edges point to the same node or at least two edges start from the same node to generate a second graph;
the second graph node merging module is used for merging nodes on the second graph based on the minimum path coverage principle with the dependency constraint to generate a third graph;
a third graph node merging module, configured to merge nodes on each third graph based on a principle that at least two paths exist between two points; for two nodes trying to be merged on two third graphs with only one path, merging the corresponding child nodes of the two nodes trying to be merged in the second graph based on the layer thickness constraint, and iterating and merging until no mergeable nodes exist in the third graphs;
and the printing path generating module is used for planning a path by taking the shortest total connecting path represented by all the nodes in the third graph after the nodes are combined as a target, calculating the connecting point of each layer, generating a final printing path and outputting a printable file.
As an embodiment, in the print pose determination module, the process of determining the model print pose is:
searching all placing postures which accord with the support constraint based on the shell model data;
selecting a placing posture corresponding to the minimum target function as a model printing placing posture;
wherein the objective function consists of a weighted sum of the flat region area and the support structure volume.
A third aspect of the present invention provides a computer-readable storage medium, on which a computer program is stored, which when executed by a processor implements the steps in the 3D-printing shell structure-oriented path generation method as described above.
A fourth aspect of the present invention provides an electronic device, comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor executes the program to implement the steps of the 3D printing shell structure-oriented path generation method as described above.
Compared with the prior art, the invention has the beneficial effects that:
(1) The invention provides a path generation method facing a 3D printing shell structure, which comprises the steps of slicing a shell model for determining a printing posture layer by layer, taking each corresponding continuous line segment as a node, constructing a corresponding graph structure based on the dependency of the node, sequentially combining the corresponding graph structures based on a set principle, finally performing model surface decomposition and path generation with continuity as a target, quantifying and greatly improving the continuity of the path, and obviously improving the quality of the model and shortening the printing time.
(2) The method comprises the steps of determining a model printing and placing posture based on shell model data; the input shell model is subjected to selecting of a placing posture suitable for printing, the model and the support are decoupled, a printing path of the support structure is generated independently firstly, and then the printing path of the model is generated, so that the support structure is easy to remove, the printing path of the model is continuous as much as possible, namely, the number of times of disconnection is as few as possible, the printing quality and speed are improved, the support is easy to remove, the labor cost is reduced, and the quality of the model is improved.
Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
FIG. 1 is a flow chart of an example of path generation for a 3D-oriented printing housing structure of the present invention;
fig. 2 is a schematic diagram of a path generation method for a 3D-printing shell structure according to an embodiment of the present invention;
FIG. 3 (a) is a schematic diagram of a setup procedure of a first graph in an embodiment of the present invention;
FIG. 3 (b) is a diagram illustrating a second process of establishing a second graph according to an embodiment of the present invention;
FIG. 3 (c) is a schematic diagram of a third example of the establishing process in the embodiment of the present invention;
FIG. 4 (a) is a third merged schematic view in an embodiment of the present invention;
FIG. 4 (b) is a schematic diagram illustrating deadlock issues in an embodiment of the present invention;
FIG. 5 is a schematic view of an iterative merge of a third graph in an embodiment of the present invention;
FIG. 6 (a) is a schematic diagram of an exemplary embodiment of an interlayer path connection 1;
FIG. 6 (b) is a schematic diagram of an exemplary embodiment of an inter-layer path connection 2;
FIG. 7 (a) is a schematic diagram of path optimization corresponding to FIG. 6 (a);
FIG. 7 (b) is a schematic diagram of the path optimization corresponding to FIG. 6 (b);
FIG. 8 (a) is a shell model to be printed;
fig. 8 (b) is a generated 3D printing path;
fig. 8 (c) is a diagram showing a result of a model product printed based on the generated 3D printing path;
fig. 8 (d) is a diagram showing the results of the smoothed model.
Detailed Description
The invention is further described with reference to the following figures and examples.
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
Example one
As shown in fig. 1 and fig. 2, the present embodiment provides a path generating method facing a 3D printing casing structure, which specifically includes the following steps:
s101: and determining the model printing and placing posture based on the shell model data.
In a specific implementation, the shell model data is stored in the form of stl or obj files.
In step S101, the process of determining the model print pose is:
s1011: and searching all placing postures which accord with the support constraint based on the shell model data.
In the process of searching for the placing posture conforming to the support constraint, the support structures required by the model are all required to fall on the ground (the situation of falling on the model does not exist), so the posture conforming to the constraint needs to be screened out firstly.
Firstly, uniformly sampling on a Gaussian sphere, enabling each sampling point to correspond to a placing posture, horizontally slicing each posture, projecting a point downwards if the point needs to be supported, and if the point is intersected with a model, representing that constraint is violated, and abandoning the posture.
S1012: selecting the placing posture corresponding to the minimum objective function as the model printing placing posture; wherein the objective function consists of a weighted sum of the flat region area and the support structure volume.
The formula of the objective function is:
E ori ＝λ*E flat +(1-λ)*E support ；
wherein
Wherein E is flat Is the area of the flat area; e support Is the support structure volume. λ is a set parameter, and is preset by human. Is selected such that E ori The smallest pose is used as the model print pose.
S102: slicing the shell model with the determined printing and placing postures layer by layer, taking each corresponding continuous line segment as a node, and constructing a first graph based on the dependency of the node.
In step S102, let G be the first graph depend ；
The model is horizontally sliced with a constant step size, and each successive line segment obtained by slicing is used as the first graph G depend If node A depends on node B, in a first graph G depend Add an edge pointing from a to B until all nodes and edges are added, as shown in fig. 3 (a).
S103: and combining the nodes on the first graph based on the principle that at least two edges point to the same node or the principle that at least two edges start from the same node to generate a second graph.
In step S103, let G be the second graph init ；
Traverse the first graph G depend If there are two or more edges pointing to or starting from the same node, then these edges are deleted, after which connected components are calculated, each as a second graph G init A node of (2), a second graph G init Edge in (D) is from the first graph G depend FIG. 3 (b) shows the inheritance of (A).
S104: and combining the nodes on the second graph based on the minimum path coverage principle with the dependency constraint to generate a third graph.
The process of generating the third graph is in the second graph G init Upper solving maximum with dependent constraintSmall path coverage problem (PC-MPC).
Specifically, in step S104, the third map G is generated OPP The process comprises the following steps:
s1041: constructing a search tree by a cluster search algorithm, wherein each node of the tree obtains a path with a set length by depth-first search, each path is used as a node, and a search range is limited by a branch-and-bound method; wherein the width of the bundle search is set to 10 in the present embodiment 4 To prevent the search space from being too large.
S1042: after the search tree is constructed, each path from the root node to each leaf represents a solution, and as shown in fig. 3 (c), the path with the minimum depth is the optimal path;
s1043: finally, a third graph G is correspondingly established for each optimal solution OPP Each node of the third graph corresponds to a node in the optimal solution, and the edges represent the dependency relationship between the nodes.
S105: combining nodes on each third graph based on the principle that at least two paths exist between two points; for two nodes trying to be merged on the two third graphs with only one path, merging the corresponding child nodes of the two nodes trying to be merged in the second graph based on the layer thickness constraint, and iterating and merging until no mergeable nodes exist in the third graphs, as shown in fig. 5.
Specifically, for each third graph G generated in the previous step OPP The following steps are performed for further combination. Fig. 4 (a) is a combinable schematic diagram of the third diagram in the present embodiment. Randomly selecting two points to try to merge, judging whether two or more paths exist between the two points, if so, deadlock can occur after merging, and the two points prohibit merging, as shown in fig. 4 (b).
And merging the corresponding child nodes of the two nodes trying to be merged in the second graph based on the layer thickness constraint, wherein the process of merging the corresponding child nodes of the two nodes trying to be merged in the second graph is as follows:
determining the corresponding child nodes of the two nodes trying to be merged on the two third graphs with only one path in the second graph;
the child nodes are extracted to reconstruct a sub-graph in which nodes are tried to be combined two by two based on the layer thickness constraint.
In a specific implementation, the process of attempting to merge two nodes into two based on the layer thickness constraint in this sub-graph is:
starting to connect the top sliced layer of the node positioned above with the end point at the same side of the next layer until the bottom sliced layer, and calculating two oblique lines;
when one of the two oblique lines meets the slope constraint, connecting the oblique line with the top layer of the node above and projecting the oblique line onto the surface of the model to be used as an upper boundary, and projecting the bottom slice layer of the node below onto the surface of the model to be used as a lower boundary;
and when the areas needing flattening, corresponding to the upper and lower boundaries, can be flattened successfully, the layer thickness constraint is not violated, and the areas are judged to be capable of being merged and generate the pre-path.
For example, the upper and lower boundaries are assigned to the Curvisleicer tool as areas that need to be flattened, and if flattening is successful, it indicates that the layer thickness constraint is not violated.
S106: and planning the path by taking the shortest total connection path represented by all the nodes in the third graph after the nodes are combined as a target, calculating the connection point of each layer, generating a final printing path, and outputting a printable file.
As an embodiment, in the process of performing path planning, the method further includes: and smoothing the total connection path characterized by all the nodes in the third graph after the nodes are combined.
For the third graph G after merging nodes OPP The partial surface of the hull model represented by each node in the figure generates a strictly continuous path, a path of each layer is actually generated in the previous step, the smooth function of the curvistile tool is called to smooth the path, path planning is performed by taking the shortest total connection path as a target, the connection point of each layer is calculated, the layers which are not connected end to end are connected in a Zig-zag mode, and the layers which are connected end to end are connected in a Spiral mode, as shown in fig. 6 (a) and fig. 6 (b). The print path is further optimized to make the path smoother and more uniform, as shown in fig. 7 (a)) And FIG. 7 (b).
Computing G with the same algorithm OPP And the printing sequence of the partial surface represented by each node is disconnected once after one path is printed every time, and the printing nozzle is lifted to the height of the highest point of the printed model, so that the collision between the printer and the model is avoided.
Since the position of the support structure has been detected, a path is generated for it layer by layer in a concentric circle filling manner, generating a print path for the support structure. It should be noted that a release agent (e.g., plastic film) is added manually after the support structure is printed for subsequent easy release from the mold.
And finally, outputting the calculated result to a printing file. Wherein the printing file comprises three-dimensional coordinates of each sampling point in the printing path, extrusion amount of clay between every two sampling points and moving speed of a printer nozzle. Wherein fig. 8 (a) shows a shell model to be printed; fig. 8 (b) is a generated 3D printing path; fig. 8 (c) is a model product result display diagram printed based on the generated 3D printing path; fig. 8 (d) is a diagram showing the results of the smoothed model product.
As can be seen from fig. 8 (a) -8 (d), the present embodiment determines the model print pose based on the shell model data; the input shell model is subjected to selecting of a placing posture suitable for printing, the model and the support are decoupled, a printing path of the support structure is generated independently firstly, and then the printing path of the model is generated, so that the support structure is easy to remove, the printing path of the model is continuous as much as possible, namely, the number of times of disconnection is as few as possible, the printing quality and speed are improved, the support is easy to remove, the labor cost is reduced, and the quality of the model is improved.
Example two
The embodiment provides a path generating system facing a 3D printing shell structure, which specifically includes the following modules:
a printing and placing posture determining module for determining a model printing and placing posture based on the shell model data;
the first graph building module is used for slicing the shell model with the printing and placing posture determined layer by layer, taking each correspondingly obtained continuous line segment as a node, and building a first graph based on the dependency of the node;
the first graph node merging module is used for merging nodes on the first graph based on the principle that at least two edges point to the same node or at least two edges start from the same node to generate a second graph;
the second graph node merging module is used for merging nodes on the second graph based on the minimum path coverage principle with the dependency constraint to generate a third graph;
a third graph node merging module for merging nodes on each third graph based on the principle that at least two paths exist between two points; for two nodes trying to be combined on the two third graphs with only one path, combining corresponding child nodes of the two nodes trying to be combined in the second graph based on the layer thickness constraint, and iteratively combining until no combinable nodes exist in the third graphs;
and the printing path generating module is used for planning a path by taking the shortest total connecting path represented by all the nodes in the third graph after the nodes are combined as a target, calculating the connecting point of each layer, generating a final printing path and outputting a printable file.
It should be noted that, each module in the present embodiment corresponds to each step in the first embodiment one to one, and the specific implementation process is the same, which is not described again here.
EXAMPLE III
The present embodiment provides a computer-readable storage medium, on which a computer program is stored, which when executed by a processor implements the steps in the path generation method for a 3D-printing housing structure as described above.
Example four
The embodiment provides an electronic device, which includes a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the 3D printing shell structure-oriented path generating method as described above.
The present invention has been described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. A path generation method facing a 3D printing shell structure is characterized by comprising the following steps:
determining a model printing and placing posture based on the shell model data;
slicing the shell model with the determined printing and placing posture layer by layer, taking each correspondingly obtained continuous line segment as a node, and constructing a first graph based on the dependency of the nodes, specifically:
horizontally slicing the model by a constant step length, taking each continuous line segment obtained by slicing as a node of the first graph, and if the node A depends on the node B, adding an edge pointing to the node B from the node A in the first graph until all the nodes and the edges are added;
merging nodes on the first graph based on the principle that at least two edges point to the same node or at least two edges start from the same node to generate a second graph, specifically:
traversing all nodes on the first graph, if two or more edges point to the same node or start from the same node, deleting the edges, then calculating connected components, each serving as a node of the second graph, and inheriting the edges in the second graph from the first graph;
merging nodes on the second graph based on the minimum path coverage principle with the dependency constraint to generate a third graph, specifically:
constructing a search tree by a cluster search algorithm, wherein each node of the tree obtains a path with a set length by depth-first search, each path is used as a node, and a search range is limited by a branch-and-bound method;
after the search tree is constructed, each path from the root node to each leaf represents a solution, and the path with the minimum depth is an optimal path;
finally, each optimal solution is correspondingly established with a third graph, each node of the third graph is corresponding to one node in the optimal solution, and the edges represent the dependency relationship among the nodes;
combining nodes on each third graph based on the principle that at least two paths exist between two points; for two nodes trying to be merged on two third graphs with only one path, merging the corresponding child nodes of the two nodes trying to be merged in the second graph based on the layer thickness constraint, and iterating and merging until no mergeable nodes exist in the third graphs;
and planning the path by taking the shortest total connection path represented by all the nodes in the third graph after the nodes are combined as a target, calculating the connection point of each layer, generating a final printing path, and outputting a printable file.
2. The 3D-printing-housing-structure-oriented path generation method of claim 1, wherein determining the model printing pose is by:
searching all placing postures which accord with the support constraint based on the shell model data;
selecting the placing posture corresponding to the minimum objective function as the model printing placing posture;
wherein the objective function consists of a weighted sum of the flat region area and the support structure volume.
3. The 3D-printing-housing-structure-oriented path generation method according to claim 1, wherein the process of merging the corresponding child nodes of the two nodes attempting to merge in the second graph based on the layer thickness constraint is:
determining the corresponding child nodes of the two nodes trying to be merged on the two third graphs with only one path in the second graph;
the child nodes are extracted to reconstruct a sub-graph, and the nodes are tried to be combined two by two in the sub-graph based on the layer thickness constraint.
4. The method for generating a path to a 3D-printing housing structure as claimed in claim 3, wherein the attempt to merge nodes two by two based on layer thickness constraint in this sub-graph is:
connecting the top sliced layer of the node positioned above with the end point at the same side of the next layer until the bottom sliced layer, and calculating two oblique lines;
when one of the two oblique lines meets the slope constraint, connecting the oblique line with the top layer of the node above and projecting the oblique line onto the surface of the model to be used as an upper boundary, and projecting the bottom slice layer of the node below onto the surface of the model to be used as a lower boundary;
and when the areas needing flattening corresponding to the upper and lower boundaries can be flattened successfully, the layer thickness constraint is not violated, and the areas are judged to be combinable and generate the pre-path.
5. The 3D-printing-oriented path generation method of a housing structure according to claim 1, wherein in the process of performing path planning, the method further comprises: and smoothing the total connection path characterized by all the nodes in the third graph after the nodes are combined.
6. A 3D printing shell structure oriented path generation system, comprising:
a printing and placing posture determining module for determining a model printing and placing posture based on the shell model data;
the first graph building module is used for slicing the shell model with the determined printing and placing posture layer by layer, taking each correspondingly obtained continuous line segment as a node, and building a first graph based on the dependency of the nodes, specifically:
horizontally slicing the model by a constant step length, taking each continuous line segment obtained by slicing as a node of the first graph, and if the node A depends on the node B, adding an edge pointing to the node B from the node A in the first graph until all the nodes and the edges are added;
a first graph node merging module, configured to merge nodes on a first graph based on a principle that at least two edges point to a same node or at least two edges start from the same node, to generate a second graph, specifically:
traversing all nodes on the first graph, if two or more edges point to the same node or start from the same node, deleting the edges, then calculating connected components, each serving as a node of the second graph, and inheriting the edges in the second graph from the first graph;
a second graph node merging module, configured to merge nodes on the second graph based on a minimum path coverage principle with dependency constraint to generate a third graph, specifically:
constructing a search tree by a cluster search algorithm, wherein each node of the tree obtains a path with a set length by depth-first search, each path is used as a node, and a search range is limited by a branch-and-bound method;
after the search tree is constructed, each path from the root node to each leaf represents a solution, and the path with the minimum depth is an optimal path;
finally, each optimal solution is correspondingly established with a third graph, each node of the third graph is corresponding to one node in the optimal solution, and the edges represent the dependency relationship among the nodes;
a third graph node merging module for merging nodes on each third graph based on the principle that at least two paths exist between two points; for two nodes trying to be combined on the two third graphs with only one path, combining corresponding child nodes of the two nodes trying to be combined in the second graph based on the layer thickness constraint, and iteratively combining until no combinable nodes exist in the third graphs;
and the printing path generating module is used for planning a path by taking the shortest total connecting path represented by all the nodes in the third graph after the nodes are combined as a target, calculating the connecting point of each layer, generating a final printing path and outputting a printable file.
7. The 3D printing housing structure-oriented path generation system of claim 6, wherein in the print pose determination module, the process of determining a model print pose is:
searching all placing postures which accord with the support constraint based on the shell model data;
selecting a placing posture corresponding to the minimum target function as a model printing placing posture;
wherein the objective function consists of a weighted sum of the flat region area and the support structure volume.
8. A computer-readable storage medium, on which a computer program is stored, which program, when being executed by a processor, carries out the steps of the method for generating a path oriented to a 3D printing shell structure according to any one of claims 1 to 5.
9. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the steps in the method of generating a path to a 3D printed housing structure according to any of claims 1-5 when executing the program.
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| CN105711102B (en) * | 2016-04-19 | 2018-01-02 | 山东大学 | A kind of 3D printing paths planning method based on your helix of Fermat |
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