False tooth support node iterative compensation method based on finite element simulation

Abstract

The invention discloses a false tooth support node iterative compensation method based on finite element simulation, and belongs to the field of selective laser melting metal printing. Comprising the following steps: presenting support stress distribution based on commercial finite element simulation software and exporting a deformation result; comparing and outputting a deviation value based on three-dimensional measurement software; carrying out loop iteration on the basis of a node iterative compensation algorithm to obtain a minimum deformation amount; performing slice printing based on an inverse compensation model result; the node iteration algorithm is designed for the problem of false tooth deformation in the prior art, the minimum deviation value can be iterated in a loop mode and reversely loaded to the initial model, and therefore the effect of reducing deformation is achieved.

Description

Technical Field

[0001] The invention belongs to the field of laser selective melting metal printing, and in particular relates to a denture bracket node iterative compensation method based on finite element simulation. Background Art

[0002] SLM is a technology that uses metal powder to completely melt under the heat of a laser beam and solidify after cooling. The density of standard metal processed by the process exceeds 99%, and it has good mechanical properties. It can also process more complex structural parts with relatively low processing costs, fast molding speed and high efficiency. Nowadays, SLM technology has become mature and is widely used in the mold field, industrial field, automotive field, medical field, aerospace field, etc.

[0003] Denture brackets are common biomedical products. Their main function is to support and consolidate the denture base. Moreover, since they are made of metal, they are not easy to break, do not affect the appearance, and are relatively convenient for later maintenance. However, during the laser selective melting process, the denture brackets often deform due to their complex physical and chemical changes, which reduces the quality of the molded parts and may cause patients to feel uncomfortable or cause oral inflammation when wearing the denture brackets. Therefore, it is particularly important to control the deformation of the denture brackets. Summary of the invention

[0004] The present invention proposes a denture bracket node iterative compensation method based on finite element simulation, which can predict the deformation of the denture bracket and effectively improve its printing accuracy.

[0005] To achieve the above objectives, the present invention adopts the following technical solutions:

[0006] A denture bracket node iterative compensation method based on finite element simulation comprises the following steps:

[0007] S1. Use commercial finite element simulation software to simulate the structural stress of additive manufacturing on the STL file of the initial model, obtain the part model after simulation deformation by setting process parameters such as support structure, laser power, scanning speed, etc., and convert it into XT format for export;

[0008] S2. Compare the initial bracket model with the model after simulation deformation by the best fitting method of the three-dimensional measurement software to check the deviation of the x, y, and z coordinates of the model;

[0009] S3, the node iteration compensation method is to pre-deform the initial geometric model. The present invention adopts a cyclic compensation scheme to continuously iterate the point cloud coordinates of the target model to improve the compensation effect; specifically, the following steps are included:

[0010] S3-1. According to the finite element simulation deformation results, the deviation is output through the 3D measurement software and reversely loaded to the initial node coordinates to complete the first compensation;

[0011] S3-3. After the first compensation is completed, the inherent strain simulation of the compensation structure is performed under the same parameters. If the deformation prediction value still does not meet the forming requirements of the arc thin-walled part, the new deformation result is compensated for the second time. This cycle is repeated until the minimum deviation is found.

[0012] The kth compensation: P n C nk =P n C n(k-1) +P n B nk =P n C n(k-1) -P n A nk

[0013] Where: P n represents the initial position of a single node n on the model surface, which is the reference point; k is the number of compensations; A nk P after deformation n Position; B nk Indicates that the reverse offset is passed to the previous compensation result, corresponding to the deformation offset point A nk And the reverse direction is equidistant; C nk represents the position of node Pn after the kth compensation;

[0014] The set of average deformation values ​​of the model after each compensation, namely:

[0015] X=(x1,x 2, …x k )

[0016] S3-4. After the kth compensation, the average deformation value of the simulation prediction model no longer decreases or shows a larger result, that is: x k-1 ≤x k , where x k-1 This is the minimum deformation predicted by the model simulation;

[0017] S4. Slice and print the predicted model, use 3D scanning and reverse engineering software to export the STL file of the denture bracket model after the predicted deformation, and slice and print it.

[0018] Beneficial effects: The present invention provides a denture bracket node iterative compensation method based on finite element simulation, which has the following advantages over the prior art:

[0019] 1. Improve the accuracy of denture brackets: The two methods of finite element simulation prediction deformation and node iterative error compensation can accurately simulate the physical properties of the denture bracket and change its deformation, thereby effectively improving the molding accuracy of the denture bracket during the SLM preparation process, thereby reducing the deformation of the final molded part;

[0020] 2. Reduce manufacturing difficulty: Adopting iterative compensation method, each node can be gradually adjusted and optimized during the manufacturing process, which can reduce manufacturing difficulty, reduce the number of trial production, improve manufacturing efficiency, and reduce R&D costs;

[0021] 3. Optimized design: By predicting the deformation of the denture framework in the SLM preparation environment through finite element simulation, the design parameters can be adjusted to optimize the structure and performance of the framework, which helps to reduce the workload in the later manufacturing and testing stages and improve the quality and performance of the product;

[0022] 4. Environmental protection and sustainability: Compared with traditional physical model testing, the present invention reduces material waste and environmental pollution, and helps to achieve a more environmentally friendly and sustainable product development process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the node iterative compensation principle in a specific embodiment of the present invention;

[0024] Figure 2 A flow chart of finite element simulation of additive manufacturing in a specific embodiment of the present invention;

[0025] Figure 3 Flow chart of the node iterative compensation principle in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0026] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments:

[0027] like Figure 1-3 As shown in FIG. 1 , a denture bracket node iterative compensation method based on finite element simulation is shown in FIG. 1 , and the specific steps are as follows:

[0028] First, a common cobalt-chromium alloy denture framework model was selected, and the denture framework was discretized into a discrete system consisting of small units of 1 mm. A diamond support structure was set up, designed in a 3D modeling software and imported into the finite element software in the form of an STL file. The laser power was set to 130 W, the scanning speed was 1400 mm / s, the layer thickness was 0.03 mm, the scanning interval was 0.06 mm, and the substrate size was 100 mm. × 100mm × 20mm, temperature 80℃, analyze and solve, calculate the stress and displacement of each unit, use commercial finite element simulation software to present the stress distribution of the bracket and export an STL file of the deformation model;

[0029] Secondly, the structure of the simulated deformed model is compared with the initial bracket model through 3D measurement software, and the x, y, and z coordinate deviations are derived;

[0030] According to the finite element simulation deformation results, the deviation is output through the 3D measurement software and reversely loaded to the initial node coordinates to complete the first compensation;

[0031] After the first compensation is completed, the inherent strain simulation of the compensation structure is performed under the same parameters. If the deformation prediction value still does not meet the forming requirements of the arc thin-walled part, the new deformation result is compensated for the second time; Figure 1 As shown, the second compensation:

[0032] P n C n2 =P n C n1 +P n B n2

[0033] Where: P n C n2 is the position vector after the second compensation; P n C n1 Position vector after the first compensation; P n B n2 P n The position vector of the reverse isometric mapping after the second offset occurs,

[0034] And so on, the kth compensation: P n C nk =P n C n(k-1) +P n B nk =P n C n(k-1) -P n A nk

[0035] Where: P n represents the initial position of a single node n on the model surface, which is the reference point; k is the number of compensations; A nk P after deformation n Position; B nk Indicates that the reverse offset is passed to the previous compensation result, corresponding to the deformation offset point A nk And the reverse direction is equidistant; C nk represents the position of node Pn after the kth compensation;

[0036] The set of average deformation values ​​of the model after each compensation, namely:

[0037] X=(x1,x2, …x k )

[0038] After the kth compensation, the average deformation value of the simulation prediction model no longer decreases or becomes larger, that is: k-1 ≤x k , where x k-1 This is the minimum deformation predicted by the model simulation;

[0039] The predicted model was sliced ​​and printed, and the STL file of the denture bracket model after predicted deformation was exported using 3D scanning and reverse engineering software, and then sliced ​​and printed.

[0040] The above are only preferred embodiments of the present invention, which cannot limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical ideas proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A denture bracket node iterative compensation method based on finite element simulation, characterized in that: The steps include: Use commercial finite element simulation software to simulate the structural stress of the initial model, and obtain and export the deformation results by setting process parameters; The initial bracket model and the model after simulation deformation are structurally compared by the best fitting method of 3D measurement software, and the output deviation is compared; The node iterative loop compensation method is used to continuously iterate the point cloud coordinates of the target model to obtain the minimum deformation; The predicted model was sliced ​​and printed, and the STL file of the denture bracket model after predicted deformation was exported using 3D scanning and reverse engineering software, and then sliced ​​and printed.

2. The denture bracket node iterative compensation method based on finite element simulation according to claim 1, characterized in that: The process parameters are support structure, laser power, scanning speed, layer thickness, scanning spacing, substrate size, and temperature.

3. The denture bracket node iterative compensation method based on finite element simulation according to claim 2, characterized in that: The supporting structure is a diamond-shaped structure.

4. The denture bracket node iterative compensation method based on finite element simulation according to claim 1, characterized in that: The node iterative loop compensation method specifically comprises the following steps: According to the finite element simulation deformation results, the deviation is output through the 3D measurement software and reversely loaded to the initial node coordinates to complete the first compensation; After the first compensation is completed, the inherent strain simulation of the compensation structure is performed under the same parameters. If the deformation prediction value still does not meet the forming requirements, the new deformation result is compensated for the second time. After the kth compensation, the average deformation value of the simulation prediction model no longer decreases or becomes larger, and the minimum deformation is obtained.

5. The method for iterative compensation of denture bracket nodes based on finite element simulation according to claim 4, characterized in that: Second compensation: P n C n2 =P n C n1 +P n B n2 Among them, P n C n2 is the position vector after the second compensation; P n C n1 Position vector after the first compensation; P n B n2 P n The position vector of the reverse isometric mapping after the second occurrence of the offset.

6. The method for iterative compensation of denture bracket nodes based on finite element simulation according to claim 4, characterized in that: The kth compensation: P n C nk =P n C n(k-1) +P n B nk Where: P n represents the initial position of a single node n on the model surface, which is the reference point; k is the number of compensations; A nk P after deformation n Position; B nk Indicates that the reverse offset is passed to the previous compensation result, corresponding to the deformation offset point A nk And the reverse direction is equidistant; C nk Represents the position of node Pn after the kth compensation.

7. The method for iterative compensation of denture bracket nodes based on finite element simulation according to claim 6, characterized in that: The set of average deformation values ​​of the model after each compensation, that is: X = (x1, x2, ... x k ).

8. The method for iterative compensation of denture bracket nodes based on finite element simulation according to claim 7, characterized in that: After the kth compensation, when x k-1 ≤x k , x k-1 This is the minimum deformation predicted by the model simulation.

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