OCCT-based 3D printing support design method for interskeletal fusion cage implant

Abstract

The invention discloses a 3D printing support design method for an interbone fusion cage implant based on OCCT. The 3D printing support design method comprises the following steps that firstly, an area to be supported is detected; for the imported fusion cage implant model, traversing all surface information of the model, and finding an area needing to be added with a support; 2, projecting a to-be-supported area; projecting the to-be-supported area to a printing plane to obtain a two-dimensional projection area of the to-be-supported part; and step 3, sampling a projection area. After the to-be-supported area is projected to the XOY plane, sampling points are evenly distributed in the projection plane according to set interval parameters, and the sampling points are screened; and 4, adding a supporting structure of the to-be-supported area. And according to the screened sampling points, supporting structures in different shapes are selected to add supports to the to-be-supported area. The support structure can be automatically generated during 3D printing of the model, and the method is of great significance to the integrity and accuracy of the model after printing is completed.

Description

Technical Field

[0001] The present invention relates to a digital orthopedic technology, and in particular to an OCCT-based 3D printing support design method for an interosseous fusion device implant. The present invention belongs to the field of computer-aided design. Background Art

[0002] Interbody fusion implants, especially intervertebral fusion devices, play a vital role in the field of orthopedics, especially spinal surgery. With the aging of the population, the incidence of spinal diseases has increased year by year, placing a huge burden on medical resources and patients' families. Traditional treatments for spinal diseases can often only relieve symptoms but cannot fundamentally solve the problem. The research and application of interbody fusion devices can significantly improve the treatment effect of spinal diseases; at the same time, compared with traditional spinal fusion, the use of interbody fusion devices can reduce surgical trauma and complications. Therefore, the research on interbody fusion implants is of great significance.

[0003] Intervertebral fusion devices manufactured using 3D printing technology can create complex, porous unit cell structures, which not only improves the degree of personalization of the design, but also greatly enhances the stability during the fusion process. However, in the 3D printing process, adding support structures is crucial. The support structure can provide the necessary stability and support during the printing process, prevent deformation or collapse during printing, and ensure the accuracy and quality of the printed object. In the current 3D printing process, adding supports mainly relies on slicing software or professional software, or manual addition. These methods are cumbersome and complicated to operate, requiring a certain degree of expertise or familiarity with software operation; in particular, manual support addition is not only time-consuming and labor-intensive, but also may cause the risk of errors. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes to use OCCT technology to integrate model import, support structure generation and model export into one, which can automatically generate support structures of different shapes, greatly simplifying the operation process and reducing the error rate when manually adding supports.

[0005] The present invention proposes a 3D printing support design method for an interosseous fusion device implant based on OCCT, which can solve the problems of complex support adding operation and high error rate in existing 3D printing.

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

[0007] A 3D printing support design method for an interosseous fusion device implant based on OCCT, comprising:

[0008] Next steps:

[0009] Step 1: Detection of the area to be supported;

[0010] Based on the imported fusion device implant model and the critical angle setting, all the free information of the model is traversed to obtain the surface that needs to be supported;

[0011] Step 2: Projection of the area to be supported;

[0012] All areas that need to be supported are projected onto the printing plane to obtain a two-dimensional projection of the area to be supported, reducing the amount of calculation and complexity of sampling.

[0013] Step 3: Sampling of the projection area;

[0014] The bounding box of the obtained two-dimensional projection area is obtained, and an appropriate sampling method is used to generate sampling points in the bounding box area according to the set spacing parameters; then the sampling points are further screened by judging whether they are inside the projection area.

[0015] Step 4: Generation of support structure;

[0016] Select support structures of different shapes, and automatically generate corresponding support structures based on the coordinate information of the sampling points, the spatial distance between the sampling points and the projection points, and Boolean operations;

[0017] Preferably, the above step 1 specifically includes:

[0018] Step 1a: Import the fusion cage implant model and use the traversal container to traverse the information of each face of the model to obtain the inclination angle of the face.

[0019] Step 1b: Compare the inclination angle of the surface with the set critical angle value. If it is smaller than the critical angle, it is marked as the area to be supported.

[0020] In step 1a, the inclination angle of the surface refers to the complementary angle between the normal vector of the surface and the XOY plane; in step 1b, the critical angle refers to the self-supporting inclination angle, which is given by the formula We get: where h is the layer thickness and L is the distance that the new layer extends beyond the previous layer.

[0021] Preferably, the above step three specifically includes:

[0022] Step 3a: Determine the bounding box of the two-dimensional projection area obtained in step 2, and use an appropriate sampling method to sample in the projection area according to the bounding box and the set spacing parameters.

[0023] Step 3b: After sampling, since the two-dimensional projection area of ​​the area to be supported is not necessarily a rectangle, it is necessary to determine whether the sampling point is inside the projection area and screen the sampling points.

[0024] In step 3a, the appropriate sampling method is the equidistant sampling method, that is, the projection distance of the projection area in the x and y directions is equally divided according to the sampling d1 and d2 to obtain the horizontal and vertical coordinates x of the sampling point i ,y i , where d1 and d2 refer to the distances between adjacent sampling points in the x and y axis directions respectively; in step 3b, the determination of whether the sampling point is inside the projection area refers to calculating the distance from the sampling point to the projection surface and determining whether the distance is small enough to determine whether the sampling point is inside the projection area.

[0025] Preferably, the support structures of different shapes in step 4 mentioned above mainly refer to cylindrical support structures and cubic support structures.

[0026] The benefit of the present invention lies in that the OCCT-based 3D printing support design method for interosseous fusion device implants is applied to the field of medical orthopedic implant design and manufacturing, which can simplify the operation process of the support part during model 3D printing and reduce the error rate caused by manual addition of support. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is the process of the 3D printing support design method of the interosseous fusion device implant based on OCCT in the present invention;

[0028] Figure 2 It is a schematic diagram of the detection area to be supported;

[0029] Figure 3 It is to project the area to be supported onto a two-dimensional plane schematic diagram;

[0030] Figure 4 This is a schematic diagram of the sampling points after screening;

[0031] Figure 5 It is a schematic diagram of the support generation of the interosseous fusion device. DETAILED DESCRIPTION

[0032] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] like Figure 1 As shown, a 3D printing support design method for an interosseous fusion device implant based on OCCT includes the following steps:

[0034] Step 1: Detection of the area to be supported;

[0035] Based on the imported fusion device implant model and the critical angle setting, all the free information of the model is traversed to obtain the surface that needs to be supported;

[0036] Step 1a: Import the fusion device implant model, use the traversal container to traverse the information of each face of the model, and obtain the inclination angle of the face. The specific calculation method is to first obtain the normal vector of the face, and then calculate it through the dot product formula;

[0037] Step 1b: Compare the inclination angle of the surface with the set critical angle value. If it is less than the value, it is marked as a support area, such as Figure 2 As shown;

[0038] The aforementioned inclination angle of the surface refers to the complementary angle between the normal vector of the surface and the XOY plane, which is obtained by the formula a·b=|a||b|cos(θ), where a is the normal vector of the surface, b is the normal vector of the horizontal plane, and θ is the angle; the critical angle refers to the self-supporting inclination angle, which is obtained by the formula We get: where h is the layer thickness and L is the distance that the new layer extends beyond the previous layer.

[0039] Step 2: Projection of the area to be supported;

[0040] Project all areas that need to be supported onto the printing plane to obtain a two-dimensional projection of the area to be supported, reducing the amount of calculation and complexity of sampling, such as Figure 3 As shown;

[0041] Using the projection algorithm provided by OCCT, the detected area to be supported is projected onto the printing plane, that is, the XOY horizontal plane, so as to obtain the two-dimensional projection area of ​​the part to be supported, so as to reduce the amount of calculation and complexity caused by three-dimensional space sampling.

[0042] Step 3: Sampling of the projection area;

[0043] Obtain the bounding box of the obtained two-dimensional projection area, use an appropriate sampling method, and generate sampling points in the bounding box area according to the set spacing parameters; then determine whether the sampling points are inside the projection area to further screen the sampling points;

[0044] Step 3a: Determine the bounding box of the two-dimensional projection area obtained in step 2, and use an appropriate sampling method to sample in the projection area according to the bounding box and the set spacing parameters.

[0045] The appropriate sampling method is the equidistant sampling method, which is to divide the projection distance of the projection area in the x and y directions equally according to the sampling d1 and d2 to obtain the horizontal and vertical coordinates x of the sampling point i ,y i , where d1 and d2 refer to the distances between adjacent sampling points in the x and y axis directions respectively; in step 3b, the determination of whether the sampling point is inside the projection area refers to calculating the distance from the sampling point to the projection surface and determining whether the distance is small enough to determine whether the sampling point is inside the projection area.

[0046] Step 3b: After sampling, since the two-dimensional projection area of ​​the area to be supported is not necessarily a rectangle, it is necessary to determine whether the sampling point is inside the projection area and screen the sampling points. The results after screening are as follows: Figure 4 As shown, spheres are used here instead of sampling points for ease of observation.

[0047] The aforementioned appropriate sampling method refers to the equidistant sampling method, that is, the projection distance of the projection area in two directions is equally divided according to the sampling sum to obtain the horizontal and vertical coordinates of the sampling points; the aforementioned judgment of whether the sampling point is inside the projection area refers to calculating the distance from the sampling point to the projection surface, judging whether the distance is small enough, so as to determine whether the sampling point is inside the projection area.

[0048] Step 4: Generation of support structure;

[0049] Select support structures of different shapes, and automatically generate corresponding support structures based on the coordinate information of the sampling points, the spatial distance between the sampling points and the projection points, and Boolean operations;

[0050] According to the sampling points selected in step 3b, support structures of different shapes are selected, and the distance between the sampling points and the corresponding projection points on the supported area is calculated as the height of the final support structure. Then, the final support structure is obtained through Boolean operation, such as Figure 5 As shown, a cylindrical support structure is selected here;

[0051] The aforementioned support structures of different shapes mainly refer to cylindrical support structures and cubic support structures;

[0052] Anything not further described in the present invention is prior art.

[0053] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A 3D printing support design method for interosseous fusion device implant based on OCCT, characterized in that: The steps include: Step 1: Detection of the area to be supported; Based on the imported fusion device implant model and the critical angle setting, all the free information of the model is traversed to obtain the surface that needs to be supported; Step 2: Projection of the area to be supported; Project all areas that need to be supported onto the printing plane to obtain a two-dimensional projection of the area to be supported, reducing the amount of calculation and complexity of sampling; Step 3: Sampling of the projection area; Obtain the bounding box of the obtained two-dimensional projection area, and generate sampling points in the bounding box area according to the set spacing parameters through the sampling method; then determine whether the sampling points are inside the projection area to further screen the sampling points; Step 4: Generation of support structure; Select support structures of different shapes, and automatically generate corresponding support structures based on the coordinate information of the sampling points, the spatial distance between the sampling points and the projection points, and Boolean operations.

2. The OCCT-based 3D printing support design method for interosseous fusion device implant according to claim 1, characterized in that: The step 1 specifically includes: Step 1a: Import the fusion cage implant model, and use the traversal container to traverse the information of each face of the model to obtain the inclination angle of the face; Step 1b: Compare the inclination angle of the surface with the set critical angle value. If it is smaller than the critical angle, it is marked as the area to be supported.

3. The OCCT-based 3D printing support design method for interosseous fusion device implant according to claim 2, characterized in that: In step 1a, the inclination angle of the surface refers to the complementary angle between the normal vector of the surface and the XOY plane; in step 1b, the critical angle refers to the self-supporting inclination angle, which is given by the formula We get: where h is the layer thickness and L is the distance that the new layer extends beyond the previous layer.

4. The OCCT-based 3D printing support design method for interosseous fusion device implant according to claim 1, characterized in that: The step three specifically includes: Step 3a: Determine the bounding box of the two-dimensional projection area obtained in step 2, and sample in the projection area by a sampling method according to the bounding box and the set spacing parameters; Step 3b: After sampling, since the two-dimensional projection area of ​​the area to be supported is not necessarily a rectangle, it is necessary to determine whether the sampling point is inside the projection area and screen the sampling points.

5. The OCCT-based 3D printing support design method for interosseous fusion device implant according to claim 4, characterized in that: In step 3a, the sampling method refers to the equidistant sampling method, that is, the projection distance of the projection area in the x and y axis directions is equally divided according to the sampling d1 and d2 to obtain the horizontal and vertical coordinates x of the sampling point i ,y i , where d1 and d2 refer to the distances between adjacent sampling points in the x and y axis directions respectively; in step 3b, the determination of whether the sampling point is inside the projection area refers to calculating the distance from the sampling point to the projection surface and determining whether the distance is small enough to determine whether the sampling point is inside the projection area.

6. The OCCT-based 3D printing support design method for interosseous fusion device implant according to claim 1, characterized in that: The support structures of different shapes in step 4 refer to cylindrical support structures and cubic support structures.

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