CN116442527A - Flexible 3D printing forming method and printing equipment based on 3D vision - Google Patents

Abstract

The invention relates to the technical field of 3D printing, in particular to a flexible 3D printing forming method and printing equipment based on 3D vision, wherein the method comprises the following steps: obtaining a three-dimensional model file of a target object, and calculating to obtain a voxel model and a point cloud model of the target object; acquiring a three-dimensional size ratio R of an axis alignment bounding box of the voxel model, and generating a filling voxel unit a with the largest bottom on the bottom surface of the voxel model according to the three-dimensional size ratio R; dividing the voxel model according to the filling voxel unit a to generate a preset number of sub-voxel units; decomposing each sub-voxel unit until sub-voxels with bounding box sizes smaller than a preset space size exist in each decomposed sub-voxel, numbering all sub-voxels to obtain a model decomposition sequence tree, wherein the model decomposition sequence tree comprises a plurality of sub-voxel sequences; printing the target object according to the model decomposition sequence tree and the point cloud model; the stability and reliability of the printing and forming process are improved.

Description

A flexible 3D printing forming method and printing equipment based on 3D vision

technical field

The invention relates to the technical field of 3D printing, in particular to a flexible 3D printing forming method and printing equipment based on 3D vision.

Background technique

3D printing technology, also known as "additive manufacturing technology", is a new manufacturing technology based on digital models, which accumulates materials layer by layer to create entities. It embodies the integration of information network technology, advanced material technology, and digital manufacturing technology. Closely combined; Among them, the Fused Deposition Modeling (FDM) process is widely used in the consumer field due to its simple structure and high cost performance. Fast, large forming size, high material utilization rate, high strength of metal printing parts, etc., and are widely used in shipbuilding, aviation, aerospace, automobile, construction and other fields.

The above-mentioned 3D printing data processing of different process types can be summarized as two sequential and strictly related processing processes: (1) digital model dimensionality reduction discrete process; (2) forming material additive manufacturing process. Among them, the discrete process of digital model dimensionality reduction is defined as follows: first, the 3D digital model (such as STL model, OBJ model, etc.) used to represent 3D geometric information is input into the 3D printing system, and then the 3D digital model is sliced layer by layer to obtain Based on the 2D contour data (SLC model, CLI model, etc.) representing two-dimensional geometric information, this link completes the dimensionality reduction and discrete process from the three-dimensional digital model to the two-dimensional digital model; finally, path planning is performed on the 2D contour digital model to obtain the The 1D processing path data representing one-dimensional geometric information, this link completes the dimensionality reduction and discrete process from the two-dimensional digital model to the one-dimensional digital model; and the subsequent cumulative manufacturing process of forming materials can be regarded as a strict reverse of the previous process, The process is defined as follows: The 3D printing system strictly follows the reverse process of "dimension reduction and discrete" according to the 1D processing path data obtained by dimension reduction and discrete, and controls the "reverse discrete" of forming materials from point to line, line to surface, and surface to body. "Material additive manufacturing is carried out in a modernized forming method. Since the previous process is filled with various strict and rigid digital model discretization algorithms, such as two-dimensional discretization slicing algorithm, one-dimensional discretization path planning algorithm, etc., and the subsequent process is strictly dependent on the previous discretization process, thus ensuring 3D Printing technology can realize the printing and manufacturing of any complex 3D model to 3D printing entity.

However, the above-mentioned printing method, on the one hand, cannot be carried out strictly in accordance with the discrete process of digital model dimensionality reduction in the follow-up forming material accumulation process, such as the processing interference caused by the mechanical structure of the equipment during the forming process, resulting failure; on the other hand, it is necessary to ensure that each equipment component of the entire 3D printing system is functioning normally and in the best condition, so as to avoid forming defects caused by equipment component problems; therefore, the existing 3D printing forming method, subsequent forming The material additive manufacturing process requires strict and rigid dependence on the discrete process of dimensionality reduction of the preceding digital model. Such a strong dependence on the 3D printing forming method reduces the stability and reliability of the printing forming process.

Contents of the invention

Based on this, it is necessary to address the above technical problems and provide a flexible 3D printing forming method and printing equipment based on 3D vision to solve the existing 3D printing forming method. The discrete process of model dimensionality reduction severely limits the forming ability and application scenarios of 3D printing.

In the first aspect, an embodiment of the present invention provides a flexible 3D printing forming method based on 3D vision, the method comprising:

Step S100: Obtain the 3D model file of the target object, perform topology reconstruction on the 3D model file to obtain the mesh model of the target object; calculate and obtain the voxel model of the target object according to the mesh model and point cloud model;

Step S200: Obtain the three-dimensional size ratio R of the axis-aligned bounding box of the voxel model, and generate the largest filling voxel unit a on the bottom surface of the voxel model according to the three-dimensional size ratio R;

Step S300: segment the voxel model according to the filling voxel unit a, and generate a preset number of sub-voxel units;

Step S400: Decompose each of the sub-voxels until there are sub-voxels whose bounding box size is smaller than the preset spatial size in each decomposed sub-voxel, and number all the sub-voxels to obtain a model decomposition a sequence tree, the model decomposition sequence tree comprising a number of sub-voxel sequences;

Step S500: Print the target object according to the model decomposition sequence tree and the point cloud model to obtain a model of the target object.

Optionally, according to the three-dimensional size ratio R, generate the largest filling voxel unit a at the bottom on the bottom surface of the voxel model, including:

According to the voxel pattern shape of the bottommost layer of the voxel model, obtaining a voxel point located in the center of the voxel pattern shape of the bottommost layer of the voxel model as a seed voxel;

According to the three-dimensional size ratio R, the seed voxel is expanded proportionally until the expanded voxel touches the outermost voxel of the voxel model;

Move the expanded voxel by one voxel point in any of the four directions of the horizontal plane. If the expanded voxel does not intersect with the outermost voxel of the voxel model, the expanded voxel The expansion is continued according to the three-dimensional size ratio R, until the expanded voxel intersects the outermost voxel of the voxel model by moving one voxel point in any direction of the four horizontal planes.

Optionally, according to the filling voxel unit a, the voxel model is divided to generate a preset number of sub-voxel units, including:

Taking the plane where the remaining five faces except the bottom surface of the filling voxel unit a is used as the segmentation plane, the voxel model is divided into eighteen sub-voxel units, and the filling voxel unit a is used as the final sub-volume white.

Optionally, decomposing each sub-voxel unit includes:

For any sub-voxel unit m except the filling voxel unit a, obtain the three-dimensional size ratio Q of the axis-aligned bounding box of the sub-voxel unit m, and according to the three-dimensional size ratio Q, in the sub-voxel unit Generate the largest filling voxel unit b at the bottom on the bottom surface of m, and use the filling voxel unit b as the final sub-voxel;

The sub-voxel unit m is recursively decomposed to generate several final sub-voxels.

Optionally, number all sub-voxels to obtain a model decomposition sequence tree, including:

Obtain the first value of the top surface on the Z axis and the second value of the bottom surface on the Z axis of each final sub-voxel;

Taking each final sub-voxel with the smallest second value as the bottom-level sub-voxel, and numbering each bottom-level sub-voxel;

For any bottom sub-voxel l, associate numbering with the bottom sub-voxel whose second value is the same as the first value of the bottom sub-voxel l in the unnumbered bottom sub-voxel , to obtain the sub-voxel sequence corresponding to the underlying sub-voxel l;

A model decomposition sequence tree is obtained according to the sub-voxel sequence corresponding to each underlying sub-voxel.

Optionally, printing the target object according to the model decomposition sequence tree and the point cloud model includes:

Decomposing the sequence tree according to the model to obtain a rough model of the target object, printing the inner filling area of the rough model in a layer-by-layer printing manner from bottom to top, and setting the printing thickness of each layer to be f;

Calculate the printing height h=i*f of the i-th layer of the rough model, and obtain the slice contour where the slice position of the i-th layer intersects with the rough model of the target according to the printing height of the i-th layer, according to the Slicing the outline, filling and printing the i-th layer;

Obtain the current point cloud model of the i-th layer of the rough model, compare the current point cloud model with the point cloud model of the target object, and obtain the remaining area of the i-th layer, according to the remaining area of the i-th layer area, print the remaining area of the i-th layer according to the preset printing thickness d, where d=f/k, k is an integer greater than 1.

Optionally, according to the remaining area of the i-th layer, the remaining area of the i-th layer is printed according to a preset printing thickness d, including:

Use the 3D vision module to position the nozzle of the printer to the inner edge of the remaining area, and print the remaining area of the i-th layer k times according to the flood filling algorithm until the thickness of the remaining area of the i-th layer is equal to the preset Print thickness f.

Optionally, the method also includes:

Calculate the height h1=i _max *f after the rough model is printed, and calculate the area to be printed above the height h1 according to the height h1 and the point cloud model _of the target object; The maximum number of layers corresponding to the rough model when printing the thickness of the layer, i _max *f≤p<(i _max +1)*f, p is the height of the rough model;

The area to be printed is printed according to the preset printing thickness d to obtain a model of the target object.

Optionally, printing the area to be printed according to the preset printing thickness d includes:

Obtain the point cloud model of the model whose current printing height is h1, and compare the point cloud model of the model whose current printing height is h1 with the point cloud model of the target object to obtain the set U of the region to be printed;

Calculate the current printing height h2=h1+j*d, where j is the number of printing times of the area to be printed, traverse the positions of different areas in the set U, and use the flood filling algorithm to print each area with a height of h2 in the set U until the current The printing height h2 reaches the maximum height of the point cloud model of the target.

In the second aspect, an embodiment of the present invention provides a printing device, the printing device includes a processor, a memory, and a printing device program stored in the memory and operable on the processor, and the processor executes the When the printing device program is described above, the 3D vision-based flexible 3D printing forming method as described in the first aspect is realized.

The beneficial effect that the present invention exists compared with prior art:

The 3D vision-based flexible 3D printing forming method of the present invention weakens the strict and rigid dependence between the subsequent forming manufacturing process and the previous model discrete process in the current 3D printing forming process during the execution process, and the 3D printing forming process In the process, the point cloud model of the printed entity collected through 3D vision is continuously compared and corrected with the original 3D model, so that the 3D entity in the actual printing can gradually approach the geometric size of the input 3D model space, thereby improving the printing process. stability and reliability.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the descriptions of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only of the present invention. For some embodiments, those of ordinary skill in the art can also obtain other drawings based on these drawings without paying creative efforts.

Fig. 1 is a schematic flow chart of a flexible 3D printing forming method based on 3D vision provided in an embodiment of the present invention;

Fig. 2 is a schematic diagram of voxel expansion provided in an embodiment of the present invention;

Fig. 3 is a schematic diagram of a sub-voxel unit segmentation provided in an embodiment of the present invention;

Fig. 4 is a schematic diagram of a voxel model decomposition provided in an embodiment of the present invention.

Detailed ways

In the following description, specific details such as specific system structures and technologies are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of the present invention. It will be apparent, however, to one skilled in the art that the invention may be practiced in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

It should be understood that when used in the present specification and appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and/or components, but does not exclude one or more other Presence or addition of features, wholes, steps, operations, elements, components and/or collections thereof.

It should also be understood that the term "and/or" used in the description of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

As used in this specification and the appended claims, the term "if" may be construed, depending on the context, as "when" or "once" or "in response to determining" or "in response to detecting ". Similarly, the phrase "if determined" or "if [the described condition or event] is detected" may be construed, depending on the context, to mean "once determined" or "in response to the determination" or "once detected [the described condition or event] ]” or “in response to detection of [described condition or event]”.

In addition, in the specification of the present invention and the description of the appended claims, the terms "first", "second", "third" and so on are only used to distinguish descriptions, and should not be understood as indicating or implying relative importance.

Reference to "one embodiment" or "some embodiments" or the like in the specification of the present invention means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the present invention. Thus, appearances of the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in other embodiments," etc. in various places in this specification are not necessarily All refer to the same embodiment, but mean "one or more but not all embodiments" unless specifically stated otherwise. The terms "including", "comprising", "having" and variations thereof mean "including but not limited to", unless specifically stated otherwise.

It should be understood that the sequence numbers of the steps in the following embodiments do not mean the order of execution, and the execution order of each process should be determined by its functions and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.

In order to illustrate the technical solution of the present invention, the following specific examples will be used to illustrate the 3D printing method in this embodiment, taking the FDM process as an example, but it is not limited to the FDM process, and can also be used in other 3D printing processes such as WAAM. The DOF manipulator is used as an example to illustrate, but it is not limited to the multi-DOF manipulator structure, it can be other multi-DOF structural devices; the 3D vision module in the method, also known as the 3D camera, can monitor the objects on the printing platform Perform 3D scanning to obtain the 3D spatial information of the object, the most direct one is the 3D point cloud data of the object on the printing platform; install the FDM print head module and 3D vision module at the end of the robot arm.

Referring to Fig. 1, it is a flexible 3D printing forming method based on 3D vision provided in the embodiment of the present invention, the method may include the following steps:

Step S100: Obtain the 3D model file of the target object, perform topology reconstruction on the 3D model file to obtain a mesh model of the target object, and calculate a voxel model and a point cloud model of the 3D model according to the mesh model.

First read the 3D model file of the object to be printed, the 3D model file records the 3D model data of the object, for example: STL file, the STL file is composed of the definition of a plurality of triangle faces, each triangle face Define the 3D coordinates of each fixed point of the triangle and the normal vector of the triangle patch; then perform topology reconstruction on the 3D model file to obtain the patch model G of the target object. According to the patch model G, the voxels of the 3D model can be calculated Model Mv, and the point cloud model Mp of the 3D model.

Those skilled in the art know that any method of performing topology reconstruction on a 3D model file in the prior art to obtain a mesh model falls within the protection scope of the present invention; The method of the model and the point cloud model all fall into the protection scope of the present invention.

Optionally, the volume of the bottommost sub-voxel model of the object targeted by the 3D vision-based flexible 3D printing forming method of the present invention is the largest.

Step S200: Obtain the three-dimensional size ratio R of the axis-aligned bounding box of the voxel model, and generate the largest filling voxel unit a on the bottom surface of the voxel model according to the three-dimensional size ratio R.

Referring to FIG. 2 , according to the existing axis-aligned bounding box calculation method, the axis-aligned bounding box E corresponding to the voxel model Mv is calculated, and the three-dimensional size ratio R of the axis-aligned bounding box E can be further calculated.

Calculate the voxel pattern shape of the bottom layer of the voxel model Mv, then select the voxel point located in the center of the pattern shape as the seed voxel a0, and record the current position.

According to the three-dimensional size ratio R calculated in the above steps, the seed voxel a0 is expanded proportionally until the expanded voxel touches the outer voxel of the voxel model Mv, and the expansion of the seed voxel a0 is stopped.

Then move tentatively on the horizontal plane, that is, the horizontal direction of the XOY plane, the steps are as follows:

1) Move the currently expanded voxel to four directions of X+1, X-1 on the X-axis and Y+1, Y-1 on the Y-axis in sequence;

2) Determine whether the expanded voxel after the movement intersects with the outermost voxel of the voxel model Mv; if the expanded voxel units after the four moves intersect, it means that the currently expanded voxel is the voxel model Mv the largest bottom-segmented voxel unit, the process ends; if the moved voxel unit does not intersect with the outermost voxel of the voxel model Mv, the inner dilated voxel is moved to that position, and then proceeds as described above The voxel step is expanded in equal proportion until the expanded voxel units after the four moves intersect, and the largest filled voxel unit a at the bottom is obtained.

Step S300: segment the voxel model according to the filling voxel unit a, and generate a preset number of sub-voxel units.

Referring to Fig. 3, the five planes of the largest voxel unit a in the voxel model Mv, that is, the plane where the right division plane 1, the rear division plane 2, the front division plane 3, the left division plane 4 and the upper division plane 5 are used as the division plane, and divide the voxel model Mv into 18 sub-voxel units.

Step S400: Decompose each sub-voxel unit until there are sub-voxels whose bounding box size is smaller than the preset spatial size in each decomposed sub-voxel, and number all sub-voxels to obtain a model decomposition sequence tree , the model decomposition sequence tree includes several sub-voxel sequences.

In this embodiment, the voxel model Mv of the 3D model that needs to be printed is taken as the processing object, and a stack set S for building a voxel decomposition sequence tree and a sub-voxel decomposition result set R are established, and S and R are initially Is empty.

In the above step S300, the central voxel located in the first layer is the voxel unit a, and the remaining 17 sub-voxels are pushed into the stack set S.

Traverse each sub-voxel unit in S, calculate the three-dimensional size ratio Q of the axis-aligned bounding box of the sub-voxel unit, and generate the largest filling voxel unit b on the bottom surface of the sub-voxel unit according to the three-dimensional size ratio Q , filling the voxel unit b as the final subvoxel.

According to the filling voxel unit b, recursively decompose the sub-voxel unit to generate several final sub-voxels. The detailed steps are as follows:

According to the depth-first strategy, each sub-voxel unit is traversed and recursively decomposed, and the sub-voxel unit at the head of the stack in the stack set S is sequentially taken out, and the sub-voxel unit b is continued according to the method in the above step S200 and step S300 Decompose until the collection stack S becomes empty again, then the current given voxel model Mv is decomposed, and the decomposed sub-voxel result set R is obtained, and the result set R includes all the final sub-voxels.

In this embodiment, the voxel model Mv decomposition termination constraint is defined: calculate the axis-aligned bounding box corresponding to the decomposed voxel, if any dimension component (X, Y or Z) of the axis-aligned bounding box is smaller than the given decomposition The minimum value indicates that the voxel is no longer decomposed, otherwise the voxel needs to be further decomposed; if the sub-voxel unit generated by the sub-voxel unit after the first division is filled with any dimension component of the axis-aligned bounding box of the voxel unit a ( X, Y or Z) is less than the given decomposition minimum value, then the sub-voxel unit will not be decomposed.

Number all final subvoxels as follows:

Take the result set R as the processing object, respectively calculate the axis-aligned bounding box of each final sub-voxel in the structure set R, and traverse the maximum value (that is, the first value) and the bottom surface of the top surface of all final sub-voxels on the Z axis The minimum value (i.e. the second value) on the Z axis, and arrange the final subvoxels in R in ascending order according to the minimum value, and number the final subvoxels according to the following rules: See Figure 4, the rules are as follows:

1) If the minimum values of the final sub-voxels are all the same, assign different letters to these final sub-voxels for numbering, such as A, B, C...;

2) If the Z-axis maximum value of the numbered final sub-voxel is equal to the Z-axis minimum value of one or more unnumbered final sub-voxels, it means that the distance between the numbered final sub-voxel and the unnumbered final sub-voxel There is an up-down dependency in the Z direction, where the lower surface of the latter is closely attached to the upper surface of the former. The latter numbering method adopts the former numbering content and adds the index number value of the corresponding sub-voxel unit close to its upper surface, such as: 1, 2, 3...;

3) If there is an unnumbered sub-voxel whose minimum value is not on the surface of the formed abutment, and whose minimum value is not equal to the maximum value of the numbered final sub-voxel, then this situation is not considered within the scope of the present invention, This can be circumvented by adding support structures to the 3D model up front.

The process of numbering the final sub-voxels in the result set R is the process of constructing the decomposition sequence tree T corresponding to the voxel model Mv.

For example, see Figure 4, the bottom voxels are A1, B1, C1, D1, taking A1 as an example, the decomposed sub-voxel in contact with the upper surface of A1 is A11, and the decomposed sub-voxel in contact with the upper surface of A11 If there are two units, they are numbered A111 and A112 respectively. Continue to number the decomposed sub-voxel units in contact with the upper surface of A112, and they are numbered A1121 and A1122 respectively. Repeat the above steps until the numbering process of all decomposition sub-voxel units in the decomposition sequence tree T is completed, then a series of orderly sub-voxel decomposition sequence trees T are formed, and the contents of T are as follows:

Step S500: Print the target object according to the model decomposition sequence tree and the point cloud model to obtain a model of the target object.

The sequence tree is decomposed according to the model to obtain the rough model of the target object, and the inner filling area of the rough model is printed by the first printing method.

According to the model decomposition tree sequence T obtained by the above steps, the rough model C composed of sub-voxel sets in T is located within the patch model G, and the space within the rough model C belongs to the internal filling area M1, and the internal filling The spatial structure of the area M1 is simple and does not contain the detailed features of the 3D model. A large preset printing thickness f can be used for fast filling printing. The specific printing process is as follows:

From the inner filling area M1, decompose the sub-voxel sequence in the voxel sequence T according to the model, traverse from bottom to top, start from the first layer, and print layer by layer according to the preset printing thickness f; the current layer The height of i is h=i*f, calculate the slice outline where the slice position intersects with the rough model in T, fill it with the conventional filling path, and then use the mechanical arm to drive the print head at the end to print according to the filling path.

The space area between the rough model and the surface of the patch model is obtained, and the space area is printed by a second printing method.

The spatial area M2 outside the rough model C and within the patch model G belongs to the area close to the skin surface of the 3D model. This part of the spatial structure contains the surface details of the 3D model, and is processed with a smaller preset printing thickness d. Fine printing, where the value of f is generally an integer multiple of d, let f=k*d, k is the number of printing times of each layer, the specific printing process is as follows:

Use the 3D vision module to scan and collect the point cloud model Mc of the printing entity on the current printing platform. By comparing the point cloud model Mp of the target object with the current point cloud model Mc, the remaining area R of the current layer i is obtained, and the space to which this area belongs In the area M2, a layer thickness of d is used for fine printing.

When printing the remaining area R, use the 3D vision module to position the printer nozzle near the inner edge of the remaining area R, and then gradually cover the remaining area R from the current position according to the "Flood Fill Algorithm". During the printing process, it is necessary to use the 3D vision module to continuously repair the remaining region R, so as to ensure that the remaining region R in the current layer can be accurately printed through 3D vision.

Print k times on the remaining region R until the layer thickness of the remaining region R reaches f, that is, d=f/k, then all the remaining regions in the current i layer can be printed.

Perform the above printing steps on the remaining area R of all layers until the value of the height h=i*f of the current printing layer reaches the highest point position of the inner filling area M1, then the spatial area of the inner filling area M1 is printed, and the three-dimensional model slice The spatial area below the position h is also printed.

For the spatial area M2, that is, the part above the height of the rough model, the thickness of the printing layer in this area is selected as d, and the printing process for this area is as follows:

Calculate the height h1=i _max *f of the rough model after printing. According to the height h1 and the point cloud model of the target, calculate the area M2 to be printed above the height h1; where, i _max is when f is the printing thickness of each layer The maximum number of layers corresponding to the rough model, i _max *f≤p<(i _max +1)*f, p is the height of the rough model;

Use the 3D vision module to collect the point cloud model of the printing model on the printing platform to obtain the point cloud model Mc' of the current printing model, and compare the point cloud model Mp of the target object with the point cloud model Mc' of the current printing model to obtain The remaining set of regions U to be printed.

Optionally, the connected regions are regarded as the same region, and the disconnected regions are regarded as different regions.

Calculate the current printing height h2=h1+j*d, j is the printing times of the area to be printed, traverse the different area positions in the set U, and the different areas in the set U are areas that are not connected to each other; use the flood filling algorithm to Each area of height h2 in the set U is printed until the current printing height h2 reaches the maximum height of the point cloud model of the target object; at the same time, the 3D vision module is used to continuously scan and collect the remaining area during the printing process, and the original point Cloud model Mp is compared to ensure accurate printing at the edge.

For example, as shown in Figure 4, the highest ear among the two ears of the model of the cat to be printed is the maximum height of the point cloud model of the object, and the left ear and the right ear are different regions in the set U, The height of the left ear is smaller than the height of the right ear. When printing these two areas, the end condition of the left ear printing is that the left ear is printed to the maximum height of the left ear itself, and the end condition of the right ear printing is that the right ear is printed to the point cloud The maximum height of the model.

Repeat the printing steps of the above-mentioned area to be printed until the printing height h2 reaches the maximum height of the point cloud model Mp of the target object, and the process can be terminated; at this point, the space area M2 is printed above the slice height h1, and the target object is obtained. Print the model.

The flexible 3D printing forming method based on 3D vision in this embodiment has the following characteristics:

(1) In the process of execution, the strict and rigid dependence between the subsequent forming manufacturing process and the previous model discrete process in the current 3D printing forming process is weakened. In the 3D printing forming process, the printed entities collected by 3D vision point cloud model, and constantly compare and correct with the original 3D model, so that the 3D entity in the actual printing can gradually approach the geometric size of the input 3D model space. Finally, the printed 3D model is from bottom to top and from inside The way to the field continues to "grow" until the printing is completed; there is no need for precise slicing of the 3D model and path planning in the early stage, and even if the printing is interrupted due to uncontrollable abnormalities during the forming process, the flexible 3D printing forming method can continue to work , so as to improve the stability and reliability of the printing forming process;

(2) The 3D model decomposition sequence tree construction method can complete the coarse-grained and orderly decomposition of the input 3D model, ensuring that the subsequent flexible 3D printing forming process is printed in an orderly manner from bottom to top and from inside to outside;

(3) A mixed layer thickness 3D printing forming method is proposed, in which the inner area is quickly printed with a large layer thickness, and the outer area is finely printed with a small layer thickness.

The present invention also provides a printing device, which includes a processor, a memory, and a printing device program stored in the memory and operable on the processor. When the processor executes the printing device program, it implements the 3D visual flexible 3D printing forming method.

The printing device also includes a 3D vision module, and the 3D vision module is used to scan the currently printed target object during the printing process, so as to generate a point cloud model.

In the above-mentioned embodiments, the descriptions of each embodiment have their own emphases, and for parts that are not detailed or recorded in a certain embodiment, refer to the relevant descriptions of other embodiments.

Those skilled in the art can appreciate that the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed by hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may use different methods to implement the described functions for each specific application, but such implementation should not be regarded as exceeding the scope of the present invention.

In the embodiments provided in the present invention, it should be understood that the disclosed device/client and method may be implemented in other ways. For example, the device/client embodiments described above are only illustrative, for example, the division of modules or units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components May be combined or may be integrated into another system, or some features may be omitted, or not implemented. In another point, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces, and the indirect coupling or communication connection of devices or units may be in electrical, mechanical or other forms.

A unit described as a separate component may or may not be physically separated, and a component displayed as a unit may or may not be a physical unit, that is, it may be located in one place, or may be distributed to multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be described in the foregoing embodiments Modifications to the technical solutions recorded, or equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of each embodiment of the present invention, and should be included in the scope of the present invention. within the scope of protection.

Claims (10)

1. A flexible 3D printing forming method based on 3D vision, comprising:

step S100: obtaining a three-dimensional model file of a target object, and performing topology reconstruction processing on the three-dimensional model file to obtain a patch model of the target object; according to the patch model, calculating to obtain a voxel model and a point cloud model of the target object;

step S200: acquiring a three-dimensional size ratio R of an axis alignment bounding box of the voxel model, and generating a filling voxel unit a with the largest bottom on the bottom surface of the voxel model according to the three-dimensional size ratio R;

step S300: dividing the voxel model according to the filling voxel unit a to generate a preset number of sub-voxel units;

step S400: decomposing each sub-voxel unit until sub-voxels with bounding box sizes smaller than a preset space size exist in each decomposed sub-voxel, numbering all the sub-voxels to obtain a model decomposition sequence tree, wherein the model decomposition sequence tree comprises a plurality of sub-voxel sequences;

step S500: and printing the target object according to the model decomposition sequence tree and the point cloud model to obtain a model of the target object.

2. The flexible 3D printing forming method based on 3D vision as claimed in claim 1, wherein generating a bottom maximum filled voxel cell a on a bottom face of the voxel model according to the three-dimensional size ratio R comprises:

according to the voxel pattern shape of the bottommost layer of the voxel model, a voxel point positioned at the center of the voxel pattern shape of the bottommost layer of the voxel model is obtained and used as a seed voxel;

according to the three-dimensional size ratio R, carrying out equal proportion expansion on the seed voxels until the expanded voxels contact the outermost voxels of the voxel model;

and moving the expanded voxel by one voxel point in any one of the four directions of the horizontal plane, if the expanded voxel does not intersect with the outermost voxel of the voxel model, continuing expanding the expanded voxel according to the three-dimensional size ratio R until the expanded voxel moves by one voxel point in any one of the four directions of the horizontal plane and intersects with the outermost voxel of the voxel model.

3. The flexible 3D printing forming method based on 3D vision according to claim 1, wherein the voxel model is segmented according to the filled voxel unit a, generating a preset number of sub-voxel units, comprising:

and taking the plane where the remaining five surfaces except the bottom surface of the filling voxel unit a are located as a segmentation plane, dividing the voxel model into eighteen sub-voxel units, and taking the filling voxel unit a as a final sub-voxel.

4. A flexible 3D printing forming method based on 3D vision as claimed in claim 3, wherein decomposing each of said sub-unit comprises:

for any sub-voxel unit m from which the filling voxel unit a is removed, acquiring a three-dimensional size ratio Q of an axis alignment bounding box of the sub-voxel unit m, generating a filling voxel unit b with the largest bottom on the bottom surface of the sub-voxel unit m according to the three-dimensional size ratio Q, and taking the filling voxel unit b as a final sub-voxel;

and carrying out recursion decomposition on the sub-voxel unit m to generate a plurality of final sub-voxels.

5. The flexible 3D printing forming method based on 3D vision as claimed in claim 4, wherein numbering all sub-volumes to obtain a model decomposition sequence tree, comprising:

acquiring a first value of the top surface of each final sub-voxel on the Z axis and a second value of the bottom surface of each final sub-voxel on the Z axis;

taking each final sub-voxel with the minimum second value as a bottom sub-voxel, and numbering each bottom sub-voxel;

for any bottom sub-voxel l, carrying out association numbering on the bottom sub-voxel with the second value identical to the first value of the bottom sub-voxel l in the un-numbered bottom sub-voxels and the bottom sub-voxel l to obtain a sub-voxel sequence corresponding to the bottom sub-voxel l;

and obtaining a model decomposition sequence tree according to the sub-voxel sequence corresponding to each bottom sub-voxel.

6. The flexible 3D printing forming method based on 3D vision according to claim 1, wherein printing the target object according to the model decomposition sequence tree and the point cloud model comprises:

according to the model decomposition sequence tree, a rough model of the target object is obtained, the internal filling area of the rough model is printed in a layer-by-layer printing mode from bottom to top, and the printing thickness of each layer is set to be f;

calculating the printing height h=i×f of the ith layer of the rough model, obtaining a slice contour of the ith layer, which is intersected with the rough model of the target object, according to the printing height of the ith layer, and performing filling printing on the ith layer according to the slice contour;

the method comprises the steps of obtaining a current point cloud model of an ith layer of the rough model, comparing the current point cloud model with a point cloud model of the target object to obtain a residual area of the ith layer, and printing the residual area of the ith layer according to a preset printing thickness d according to the residual area of the ith layer, wherein d=f/k, and k is an integer larger than 1.

7. The flexible 3D printing forming method based on 3D vision as claimed in claim 6, wherein printing the remaining area of the i-th layer according to a preset printing thickness D according to the remaining area of the i-th layer comprises:

and positioning the nozzle of the printer to the inner edge position of the residual area through the 3D vision module, and printing the residual area of the ith layer k times according to a flood filling algorithm until the thickness of the residual area of the ith layer is equal to the printing thickness f.

8. The 3D vision-based flexible 3D printing forming method of claim 6, further comprising:

calculating the height h1=i of the printed rough model _max * f, calculating to obtain a region to be printed above the height h1 according to the height h1 and the point cloud model of the target object; i.e _max I is the maximum layer number corresponding to the rough model when f is the printing thickness of each layer _max *f≤p<(i _max +1) f, p is the height of the asperity model;

and printing the region to be printed according to the preset printing thickness d to obtain the model of the target object.

9. The flexible 3D printing forming method based on 3D vision as claimed in claim 8, wherein printing the region to be printed according to the preset printing thickness D comprises:

acquiring a point cloud model of a model with the current printing height of h1, and comparing the point cloud model of the model with the current printing height of h1 with the point cloud model of the target object to obtain a set U of the region to be printed;

calculating the current printing height h2=h1+j d, wherein j is the printing times of the region to be printed, traversing different region positions in the set U, and printing each region with the height h2 in the set U by adopting a flood filling algorithm until the current printing height h2 reaches the maximum height of the point cloud model of the target object.

10. A printing apparatus, characterized in that the printing apparatus comprises a processor, a memory and a printing apparatus program stored in the memory and executable on the processor, the processor implementing the 3D vision-based flexible 3D printing forming method according to any one of claims 1 to 9 when executing the printing apparatus program.