Welding gun pose planning method for additive repair in confined space

Abstract

The application discloses a welding gun posture planning method for additive repair in a limited space, relates to the technical field of additive remanufacturing, and solves the technical problem of the welding gun being prone to interference with the existing appearance of a part during additive repair under the condition of a limited space, the need to change the posture according to actual conditions, and the improvement of forming quality, and the technical solution points are as follows: S1: obtaining three-dimensional point cloud data of a model surface of a damaged part and a repair path; S2: selecting a plurality of sampling points on the repair path, and calculating a reachable interval of a stacking posture of each sampling point position; S3: calculating the best posture of the welding gun at the sampling point position according to process requirements; and S4: judging whether the best posture is located in the reachable interval, and if not, selecting a direction closest to the best posture in the reachable interval. The welding gun is prone to interference with the existing appearance of a part during the additive repair process under the condition of a limited space, and the forming quality and the automation level of the additive repair are improved.

Description

Technical Field

[0001] This application relates to the field of additive remanufacturing technology, and in particular to a welding torch posture planning method for additive repair in confined spaces. Background Technology

[0002] Modern industry and defense rely heavily on equipment, and under certain conditions, on-site repair of damaged parts is necessary. Additive remanufacturing technology can be used for on-site repair of damaged parts, enabling equipment to quickly regain operational capability, which has significant military and economic implications. Currently, additive remanufacturing technology adds material based on the existing morphology of the damaged part. This requires consideration of the existing morphology, and the welding torch trajectory planning must not only consider interference with the existing morphology but also adjust the deposition posture according to the local morphology and damage characteristics to ensure forming quality.

[0003] Although research on electric arc additive repair is extensive, research on trajectory planning for additive repair of damaged parts is still insufficient, and there is no trajectory planning algorithm applicable to complex morphologies.

[0004] To address the aforementioned issues, the article titled "Research on the Characteristics and Trajectory Planning of Conformal Additive Forming of Cavity Arc Wire for Automotive Forging Dies" proposes a method for discrete block division and global contour trajectory planning of complex surfaces based on clustering algorithms, ensuring the welding torch maintains a horizontal welding posture on the complex surface throughout the repair process. The article "Research on Path Planning for Arc Additive Remanufacturing Based on Robots" proposes and develops a path planning algorithm for the remanufacturing process. Existing research has not considered the need for the welding torch to change its posture to ensure forming quality under space-constrained conditions.

[0005] Chinese invention patent application number CN202210148211.4 discloses an intelligent additive repair system and method for damaged objects. It obtains a three-dimensional mesh model of the object to be repaired and generates a repair trajectory using a three-dimensional repair trajectory planning algorithm. However, it does not consider the problem of interference between the welding torch and the existing shape of the part under spatial constraints, and does not generate the optimal posture for the local shape.

[0006] In summary, existing literature has not yet resolved issues such as the easy interference between the additive repair welding torch and the existing shape of the part under space-constrained conditions, and the need to change the posture according to the actual situation to improve the forming quality. Summary of the Invention

[0007] This application provides a welding torch posture planning method for additive repair in confined space. Its technical purpose is to solve the problem that the welding torch is prone to interference with the existing shape of the part during additive repair under confined space conditions, and that the posture needs to be changed according to the actual situation to improve the forming quality.

[0008] The above-mentioned technical objective of this application is achieved through the following technical solution:

[0009] A welding torch attitude planning method for additive repair in confined spaces, characterized by comprising:

[0010] S1: Obtain the 3D point cloud data and repair path of the surface of the damaged part model;

[0011] S2: Select several sampling points on the repair path and calculate the reachable range of the welding gun stacking posture at each sampling point;

[0012] S3: Calculate the optimal posture of the welding torch at the sampling point according to the process requirements;

[0013] S4: Determine whether the optimal posture is within the reachable range. If so, the optimal posture is the welding torch posture. Otherwise, select the direction closest to the optimal posture within the reachable range as the welding torch posture.

[0014] S5: Repeat steps S3 to S4 until the welding gun posture planning for all sampling points is completed;

[0015] In step S2, the calculation of the reachable interval includes:

[0016] For those located in the vertical plane The three-dimensional point cloud data set is obtained from the above, and represented as: ;

[0017] For sets All points and sampling points The slope of the connecting line is calculated and expressed as:

[0018] ;

[0019] Based on the slope Final point and points , is represented as:

[0020] ;

[0021] in, Point of x, y, z coordinate; Indicates sampling point of x, y, z coordinate; ;

[0022] With sampling points Using the horizontal plane as a reference, the angle of the welding torch tilting upwards is positive, and the angle tilting downwards is negative. This applies to the intersection line. The upper limit of the actual stacking angle of the welding torch within the range and lower limit To perform the calculation, and The angular space between them is the reachable interval.

[0023] Furthermore, in step S2, the repair path is represented as a set of sampling points. Based on the acquired 3D point cloud data, any sampling point The spatial surface normal vector at the location is represented as: According to the normal vector of the space surface The vertical plane is determined by the z-axis. Then the vertical plane Represented as: ; Obtain the vertical plane Intersection with the damaged part model Then the intersection line The angular interval between these points is the reachable interval; where, .

[0024] Furthermore, the sampling points The calculation of the normal vector of a spatial surface includes:

[0025] For sampling points Selecting nearby points is represented as ,make:

[0026] ;

[0027] ;

[0028] ;

[0029] Then the normal vector of the space surface Represented as: .

[0030] Furthermore, in step S3, for the intersection line The upper limit of the actual stacking angle of the welding torch within the range and lower limit The corresponding directions , To perform the calculation, then in and The direction between them is the optimal posture of the welding torch at the sampling point.

[0031] Furthermore, step S4 includes: determining the optimal orientation of the welding torch at the sampling point location. Normal vector of the sampling point space surface The included angle Perform calculations, based on For the best posture The welding torch posture is determined by whether it is within the reachable range. Then the welding torch posture Represented as:

[0032] .

[0033] The beneficial effects of this application are as follows: This application provides a welding torch posture planning method for additive repair in confined space, which solves the problem that the welding torch of additive repair is prone to interference with the existing shape of the part under confined space conditions, and that the posture needs to be changed according to the actual situation to improve the forming quality. It improves the automation level and forming quality of additive repair technology, and promotes the application of additive remanufacturing technology in modern industrial and military fields. Attached Figure Description

[0034] Figure 1 This is a flowchart of the welding torch posture planning method described in this application;

[0035] Figure 2 This is a schematic diagram illustrating the calculation method for the reachable range of the welding torch stacking posture at the sampling point location in this application;

[0036] Figure 3 This is a schematic diagram of the three-dimensional point cloud data and repair path of the damaged part model in the embodiments of this application;

[0037] Figure 4 This is a schematic diagram illustrating the solution of the reachable interval of the welding gun accumulation posture at the sampling point position on the repair path of the damaged part model in this application embodiment;

[0038] Figure 5 This is a simulation diagram of the additive repair welding torch posture calculation results in the embodiments of this application. Detailed Implementation

[0039] The technical solution of this application will be described in detail below with reference to the accompanying drawings.

[0040] like Figure 1 As shown, the welding torch attitude planning method for additive repair in confined spaces described in this application includes:

[0041] S1: Obtain the 3D point cloud data and repair path of the surface of the damaged part model;

[0042] S2: Select several sampling points on the repair path and calculate the reachable range of the welding gun stacking posture at each sampling point;

[0043] S3: Calculate the optimal posture of the welding torch at the sampling point according to the process requirements;

[0044] S4: Determine whether the optimal posture is within the reachable range. If so, the optimal posture is the welding torch posture. Otherwise, select the direction closest to the optimal posture within the reachable range as the welding torch posture.

[0045] S5: Repeat steps S3 to S4 until the welding gun posture planning for all sampling points is completed.

[0046] See Figure 2 In step S2, the repair path is represented as a set of sampling points. Based on the acquired 3D point cloud data, any sampling point The spatial surface normal vector at the location is represented as: According to the normal vector of the space surface The vertical plane is determined by the z-axis. Then the vertical plane Represented as: ; Obtain the vertical plane Intersection with the damaged part model Then the intersection line The angular interval between these points is the reachable interval; where, .

[0047] For sampling points Calculate the spatial surface normal vector at the location, for the sampling point. Selecting a series of nearby points, denoted as ,make:

[0048] ;

[0049] ;

[0050] ;

[0051] Then the normal vector of the space surface Represented as: .

[0052] As a specific embodiment, the intersection line The calculation is performed based on the actual stacking angle range of the welding torch, including: for those located in the vertical plane. Up or The three-dimensional point cloud data sets of small areas on both sides (the size of which is determined by the point cloud density and the welding torch size) are acquired and represented as follows: For sets All points and sampling points The slope of the connecting line is calculated and expressed as:

[0053] ;

[0054] Based on the slope Final point and points , is represented as:

[0055] ;

[0056] in, Point of x, y, z coordinate; Indicates sampling point of x, y, z coordinate; .

[0057] With sampling points Using the horizontal plane as a reference, the angle of the welding torch tilting upwards is positive, and the angle tilting downwards is negative. This applies to the intersection line. The upper limit of the actual stacking angle of the welding torch within the range and lower limit To perform the calculation, and The angular space between them is the reachable interval.

[0058] In step S3, for and The corresponding directions , To perform the calculation, then in and The direction between them is the optimal posture of the welding torch at the sampling point.

[0059] In a specific embodiment, step S4 includes: determining the optimal posture of the welding torch at the sampling point location. Normal vector of the sampling point space surface The included angle Perform calculations, based on For the best posture The welding torch posture is determined by whether it is within the reachable range. Then the welding torch posture Represented as:

[0060] .

[0061] The following specific examples further illustrate the effectiveness of the method for calculating the attitude of a welding torch in confined space additive repair as described in this application, and the calculation results of the welding torch attitude.

[0062] Example 1: This example illustrates a welding torch attitude planning method for additive repair in confined spaces, applicable to applications such as... Figure 3 Repair of the damaged parts shown Figure 4This is a 3D point cloud data of the damaged part model and a schematic diagram of the repair path.

[0063] The specific steps of the welding torch attitude planning method for additive repair are as follows:

[0064] (1) Read the three-dimensional point cloud data and repair path of the part to be repaired. The repair path in this embodiment is as follows: Figure 4 As shown, the total length of the repair path is 125mm, and the distance from the part surface is 2mm.

[0065] (2) Select sampling points at equidistant intervals of 5mm on the repair trajectory, for a total of 26 sampling points, and calculate the reachable range of the stacking posture at each sampling point. Figure 4 This diagram illustrates the calculation method for the reachable range of the welding torch position and attitude at a specific sampling point. Thirty-two points are selected within a 10mm*10mm*10mm radius around the sampling point to calculate the spatial surface normal vector at that position, and then the reachable range of the position and attitude is determined.

[0066] (3) Calculation findings < < Therefore, the optimal welding torch posture is selected as the final welding torch posture at that point, and then the welding torch posture at the next sampling point is calculated until all sampling points are calculated.

[0067] The additive repair welding torch attitude planning is performed using the algorithm in this embodiment, and the final repair trajectory welding torch attitude is as follows: Figure 5 As shown.

[0068] It can be seen that the results obtained from the additive repair welding torch posture calculation in this embodiment can allow the welding torch to change its posture under space-constrained conditions during the additive repair process in order to achieve the optimal welding posture and improve the forming quality.

[0069] It will be understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for torch pose planning for confined space additive repair, the method comprising: Comprise: S1: acquire the three-dimensional point cloud data of the surface of the defective part model and the repair path; S2: select a plurality of sampling points on the repair path, and calculate the reachable interval of the welding gun accumulation posture at each sampling point position; S3: calculate the best posture of the welding gun at the sampling point position according to the process requirements; S4: judge whether the best posture is located in the reachable interval, if yes, the best posture is the welding gun posture, if not, select the direction closest to the best posture in the reachable interval as the welding gun posture; S5: repeat steps S3 to S4 until the welding gun posture planning of all sampling points is completed; In step S2, the calculation of the reachable interval comprises: A set of three-dimensional point cloud data located on a vertical plane is acquired and represented as: ; On the set All points in the set and the sampling point The slope of the line connecting the two points is calculated and represented as: ； According to the slope Eventually, the point And the point Is expressed as: ； wherein representing a point of x, y, z coordinates; representing a point of x, y, z coordinates; ; With sampling points Using the horizontal plane as a reference, the angle of the welding torch tilting upwards is positive, and the angle tilting downwards is negative. This applies to the intersection line. The upper limit of the actual stacking angle of the welding torch within the range and lower limit To perform the calculation, and The angular space between them is the reachable interval.

2. The method of claim 1, wherein, The step S2 represents the repair path as a set of sampling points According to the obtained three-dimensional point cloud data, the spatial surface normal vector at any sampling point is represented as: According to the spatial surface normal vector and the vertical direction z-axis, the vertical plane is determined The vertical plane is represented as: The intersection line between the vertical plane and the damaged part model is obtained The angle interval between the intersection line is the reachable interval; wherein, 3. The method of claim 2, wherein, The sampling points The calculation of the spatial surface normal vector of the point includes: The sampling points are selected near the point and are denoted by and let ； ； ； Then the spatial surface normal vector is expressed as: .

4. The method of claim 3, wherein, In step S3, for the intersection line The upper limit of the actual stacking angle of the welding torch within the range and lower limit The corresponding directions , To perform the calculation, then in and The direction between them is the optimal posture of the welding torch at the sampling point.

5. The method of claim 4, wherein, Step S4 includes: determining the optimal posture of the welding torch at the sampling point location. Normal vector of the sampling point space surface The included angle Perform calculations, based on For the best posture The welding torch posture is determined by whether it is within the reachable range. Then the welding torch posture Represented as: 。

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