Pipe component CAD vector model sweep splicing area processing method and device based on isoparametric line intersection

Abstract

The application discloses a kind of vector model sweep splicing area processing method and equipment based on isogonic line intersection. In computer, each preliminary sweep surface is generated by traversing sweep contour and sweep path;Surface extension is carried out along tangential direction to obtain forming sweep surface, and the distribution of isogonic line u-axis coordinate is extracted according to step bisection method at sweep splicing area, curve intersection is obtained by extracting isogonic line, and surface intersection line is obtained by fitting intersection point;Forming sweep surface after geometric degeneration operation constitutes CAD sweep model by using surface splicing processing.The application can make computer generate model quickly, efficiently and accurately, can control the accuracy of intersection line, can be used to solve the problems such as long time consumption and failure in sweep modeling complex feature transition processing in prior art, reduce the complexity of calculation, improve the stability of modeling, significantly improve the performance of computer calculation and processing, the calculation efficiency is improved several times, and support real-time interaction level response.

Description

Technical Field

[0001] This invention relates to the field of computer-aided design (CAD) technology, specifically, to a method and device for processing the sweeping and splicing area of ​​a CAD vector model of a pipe component based on isoparametric line intersection. Background Technology

[0002] In computer-aided design (CAD) systems, sweeping is an important modeling method, with the handling of transition regions being the most challenging aspect. Traditional sweeping transition processing employs a method of "surface intersection + intersection line segmentation." However, surface intersection suffers from computational complexity and unstable results, leading to numerous challenges in engineering applications such as the time consumption of processing complex sweeping features potentially reaching minutes, the algorithm's complete failure in certain special cases, and the difficulty in guaranteeing result accuracy.

[0003] For example, the typical workflow of conventional sweep modeling systems such as OCCT is as follows: calculate the sweep surface, obtain the sweep topological edges, and assemble the sweep topological model. The sweep topological edges include the sweep edges along the sweep path, the sweep contour, and the intersection lines at the sweep joints. The intersection lines at the joints are usually generated by surface-to-surface intersection calculations. However, surface-to-surface intersection calculations suffer from unstable results and complex processes.

[0004] Currently, existing technologies have not yet proposed effective solutions to the aforementioned problems. Summary of the Invention

[0005] To address the problems existing in the background technology, this invention proposes a method and device for processing the sweeping and splicing region of a CAD vector model of a pipeline component based on isoparametric line intersection. By transforming the complex surface intersection problem into a simplified line intersection problem, the method achieves dimension reduction processing, thereby significantly improving the efficiency and numerical stability of computer processing.

[0006] The technical solution adopted in this invention is:

[0007] I. A method for processing swept and stitched regions of CAD vector models based on isoparametric line intersection, the method comprising the following steps:

[0008] The first step is to generate the swept surface.

[0009] In the computer, the sweep profile and sweep path are traversed, and a preliminary sweep surface is generated for each path curve along the sweep profile.

[0010] The swept splicing area is the transition region between two swept surfaces formed by sweeping the contour shape curve along two adjacent path curves in the sweeping path.

[0011] The isoparametric line is a three-dimensional curve along the path curve on the swept surface.

[0012] The second step is to extend the swept surface.

[0013] For each initial swept surface, extend the surface along the tangential direction at both ends of its own path curve to obtain the shaped swept surface; at this time, the shaped swept surfaces generated by every two adjacent path curves intersect, and the area at the intersection is taken as the swept splicing area.

[0014] In this invention, the u-axis direction is along the sweep profile, and the v-axis direction is along the sweep path.

[0015] The third step is to adaptively extract isoparametric coordinates.

[0016] At each swept splicing area, the u-axis position coordinates of the isoparametric lines of the adjacent formed swept surfaces are extracted using a stepped bisection method.

[0017] The fourth step is to generate the surface intersection line by fitting the intersection of the isoparametric lines.

[0018] For each swept splicing area, isoparametric lines are established on two adjacent swept surfaces using the u-axis position coordinates of isoparametric lines to find the intersection of curves, and a series of intersection points are obtained and fitted to obtain the surface intersection line.

[0019] Step 5: Boundary sweeping treatment

[0020] The intersection lines of the curved surfaces are used to cut and splice each pair of adjacent shaped swept surfaces. Then, each swept surface is checked for geometric degradation and geometric degradation is performed. The final shaped swept surfaces form the CAD swept model.

[0021] The sweep profile is a closed-loop or open-loop contour curve, which can be composed of multiple straight lines / curves connected end to end, with smooth or non-smooth transitions between the straight lines / curves. The sweep path is mainly composed of multiple coplanar path curves connected end to end in sequence. All path curves are coplanar.

[0022] The third step specifically involves:

[0023] T1. Initially, the entire swept profile is considered as a curve interval along the u-axis.

[0024] T2. For each curve interval along the u-axis, along the u-axis, take the two endpoints and the midpoint of the curve interval along the u-axis, establish the line connecting the two endpoints as the chord length, and calculate the vertical distance from the midpoint to the chord length as the chord height.

[0025] T3. Determine if the chord height is within the preset tolerance value and proceed accordingly:

[0026] If the chord height is within the preset tolerance (including or equal to the preset tolerance), the process ends;

[0027] If the chord height is not within the preset tolerance, the current U-axis curve interval is subdivided in a binary manner, that is, the original U-axis curve interval is divided into two U-axis curve intervals.

[0028] T4. Return to step T2 above, and repeat T2~T3 for processing until the chord height of each curve interval in the u-axis direction is within the preset tolerance.

[0029] T5. The distribution of all current curve intervals along the u-axis is used as the distribution of isoparametric lines, and the coordinate parameters of the boundary points between adjacent curve intervals along the u-axis are used as the u-axis position coordinates of the isoparametric lines.

[0030] The final judgment and processing are based on whether the preset tolerance can be met. If it can, the subdivision stops; otherwise, the subdivision continues.

[0031] The fourth step is specifically as follows:

[0032] S1. Based on the u-axis position coordinates of all isoparametric lines of the shaped swept surface obtained in step 3, establish isoparametric lines on two adjacent shaped swept surfaces. Take two isoparametric lines on adjacent shaped swept surfaces with the same u-axis position coordinates as two adjacent isoparametric lines and find the intersection point between the two adjacent isoparametric lines.

[0033] S2. The following judgment and processing are performed on the number of intersection points to be calculated:

[0034] If there is only one intersection point, then that intersection point is retained as a valid intersection point;

[0035] If there are only two intersection points, the optimal intersection point is selected by combining the tangential vector with the three-dimensional position.

[0036] S3. Use a spline curve fitting algorithm to fit all intersection points to obtain a new fitted intersection line, and use the fitted intersection line as the surface intersection line between two shaped swept surfaces.

[0037] The process of selecting the optimal intersection point based on the tangential vector and the three-dimensional position is as follows:

[0038] S21. Extract the path tangent vector v of each of the two path curves corresponding to two adjacent isoparametric lines at the connection point. c1 and v c2 , the tangent vectors of the two paths v c1 and v c2 Performing a cross product yields the first reference normal N1;

[0039] S22. Traverse each intersection point between two adjacent isoparametric lines, extract the intersection tangent vectors v1 and v2 of the two adjacent isoparametric lines at each intersection point, and perform a cross product of the two intersection tangent vectors v1 and v2 to obtain the second reference normal N2.

[0040] S23. Retain the same intersection point of the first reference normal N1 and the second reference normal N2;

[0041] S24. Finally, the following judgments and processes are performed:

[0042] If only one intersection point is retained, then that intersection point is the optimal intersection point.

[0043] If there are multiple intersection points to retain, the intersection point that is closest in three dimensions to the connection point between the two path curves corresponding to the two adjacent isoparametric lines is taken as the optimal intersection point.

[0044] The computer used is a personal computer, FPGA, microcontroller, etc.

[0045] II. A computer device, comprising a memory and a processor, wherein the memory stores a computer program, characterized in that the processor executes the computer program to implement the steps of the above-described method.

[0046] III. A computer-readable storage medium having a computer program stored thereon, characterized in that the computer program, when executed by a processor, implements the steps of the above-described method.

[0047] The goal of this invention is to optimize the swept splicing area to obtain an optimized transition connection between two swept surfaces, and to obtain an accurate isoparametric intersection line between the two swept surfaces in three dimensions, which can then be used for modeling the transition area, making the model processing more efficient and accurate.

[0048] The beneficial effects of this invention are:

[0049] This invention is a solution for rapidly generating CAD sweep models based on sweep contours and sweep paths, enabling computers to generate models quickly, efficiently, and accurately. It can be used to solve problems such as long processing time and failures in the complex feature transition processing of sweep modeling in existing technologies.

[0050] This invention innovatively performs isoparametric line intersection processing on curved surfaces, transforming the intersection processing of swept splicing regions from surface-to-surface intersection to line-to-line intersection, thereby reducing computational complexity and improving modeling stability.

[0051] Compared to the sweep modeling algorithm of the open-source geometry library OCCT, this invention can significantly improve the performance of computer computing in complex curved surface scenes, increasing computational efficiency by several times and supporting real-time interactive response.

[0052] Meanwhile, the present invention can establish isoparametric lines through a bisection subdivision method, and the accuracy of the intersection line can be quickly and effectively controlled by a preset tolerance, thereby meeting the engineering accuracy requirements. Attached Figure Description

[0053] Figure 1 This is a flowchart illustrating the overall process of the method of the present invention.

[0054] Figure 2 This is a schematic diagram of the circular sweep profile sweeping along two circular arc path curves in the example.

[0055] Figure 3 This is a schematic diagram of the swept surface generated by sweeping a circular contour curve along a circular arc path curve in the example.

[0056] Figure 4 A schematic diagram showing the result of extending the swept surface along the tangential direction of the endpoint of the path curve.

[0057] Figure 5 A schematic diagram of two binary subdivision iterations for isoparametric line density control of an instance;

[0058] Figure 6 A schematic diagram of the instance sweep results and extracted isoparameter lines;

[0059] Figure 7 This is a schematic diagram of the closed sweep profile and closed sweep path for an example.

[0060] Figure 8 A schematic diagram illustrating the selection of multiple intersection points for finding intersections of isoparametric lines in an instance.

[0061] Figure 9 This is a schematic diagram of sweep degradation along the sweep path for an example closed sweep profile;

[0062] Figure 10 This is a schematic diagram of the sweeping of an example pipe component;

[0063] Figure 11 Schematic diagram of sweeping component 1;

[0064] Figure 12 This is a schematic diagram of sweeping component 2. Detailed Implementation

[0065] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0066] like Figure 1 As shown, embodiments of the present invention are as follows:

[0067] Example 1 is as follows:

[0068] Step 1: Generate the swept surface.

[0069] In the computer, the sweep profile and sweep path are traversed, and a preliminary sweep surface is generated for each path curve along the sweep profile.

[0070] The contour shape curve is swept along a sweep path composed of multiple sequentially connected path curves to form a complete swept surface model. For example, a circular arc contour shape curve along a straight path curve can generate a cylindrical surface, and a circular arc contour shape curve along a circular arc path curve can generate a surface of revolution. In specific implementations, it can be done as follows: Figure 2 As shown, the circular sweep profile sweeps along two circular arc path curves.

[0071] Sweep splicing area: When the sweep path contains multiple path curves, the transition area of ​​the sweep surfaces corresponding to the two consecutive path curves.

[0072] Isoparametric lines: In the UV parameter space of a surface, a three-dimensional curve located on the surface with a fixed parameter v is called an isoparametric line. In specific implementations, the path curve direction is used as the v parameter direction, and the contour shape curve direction is used as the u parameter direction, thus forming the UV parameter space of the surface. In the UV parameter space of the surface, the three-dimensional curve located on the surface with a fixed parameter u is called an isoparametric line. The two isoparametric lines formed by the sweeping of two adjacent path curves constitute a pair of isoparametric lines.

[0073] The input sweep profile P consists of n profile shape curves, each of which is denoted by P. i (1≤i≤n), the sweep path C consists of m path curves, let each path curve be C. j (1≤j≤m). Based on the i-th contour shape curve P i and the j-th path curve C j The definition generates the corresponding swept surface S ij Iterate through all contour shape curves and path curves to generate all swept surfaces.

[0074] like Figure 3 As shown, with the swept surface S 11 For example, the initial swept surface S is obtained by sweeping the swept profile P1 along the swept path C1. 11 .

[0075] Step 2: Extend the swept surface.

[0076] For each path curve, the initial swept surface generated is stretched along the tangential direction at both ends of its own path curve to obtain the shaped swept surface. At this time, the shaped swept surfaces generated by every two adjacent path curves intersect, and the area at the intersection is called the swept splicing area. That is, each swept splicing area has two intersecting shaped swept surfaces. The u-axis direction of the swept surface parameter space corresponds to the swept profile, and the v-axis direction corresponds to the swept path.

[0077] For example, each initial swept surface S ij Along the path curve C j Extend the surface along the direction of the endpoint tangent vector to obtain a new shaped swept surface TS. ij At this point, in each swept splicing region, there are two formed swept surfaces TS. ij TS i(j+1) These two formed swept surfaces intersect in an area, which is the swept splicing area. In the surface parameter space UV of each swept surface TS, the profile shape curve P... i The direction is taken as the u-axis, and the path curve is C. j The direction is taken as the v-axis.

[0078] like Figure 4 As shown, the initial swept surface S 11 The shaped swept surface TS is obtained by extending the end point of C1 tangentially. 11 Preliminary sweep of surface S 12 The shaped swept surface TS is obtained by extending the tangential direction in the opposite direction from the starting point of C2. 12 .

[0079] Step 3: Adaptive extraction of isoparametric coordinates.

[0080] T1. Initially, the entire sweep profile is treated as a single u-axis curve interval; the u-axis direction is along the sweep profile direction. Then, each u-axis curve interval is processed according to the following procedure.

[0081] T2. For each curve interval along the u-axis direction, along the u-axis direction of the swept profile of the forming swept surface, take the two endpoints and the midpoint of the curve interval along the u-axis direction. The midpoint is the middle point. Establish the line connecting the two endpoints as the chord length. Calculate the vertical distance from the midpoint to the chord length formed by the two endpoints as the chord height.

[0082] T3. Determine if the chord height is within the preset tolerance value and proceed accordingly:

[0083] If the chord height is within and equal to the preset tolerance, then the current curve interval subdivision processing in the U-axis direction ends.

[0084] Otherwise, if the chord height is not within the preset tolerance, the current curve interval in the u-axis direction will be subdivided in a binary manner, and then the curve interval will be further subdivided, that is, the original curve interval in the u-axis direction will be divided into two curve intervals in the u-axis direction.

[0085] T4. Return to step T2 above, and repeat T2~T3 for processing until the chord height of each curve interval in the u-axis direction is within the preset tolerance.

[0086] T5. The current distribution of all curve intervals in the u-axis direction is used as the distribution of isoparameter lines to be extracted. The boundary points between adjacent curve intervals in the u-axis direction (that is, the coordinate parameters of the two endpoints of the curve intervals in the u-axis direction along the u-axis direction) are used as the u-axis position coordinates of the isoparameter lines, which are also the discrete points used to obtain the curve intersection lines for the subsequent forming swept surface.

[0087] In practice, the sweep profile curve has two endpoints, and in actual settings, the two endpoints overlap, thus forming a closed loop.

[0088] In the embodiment, each swept splicing area forms a swept curved surface TS. ij TS i(j+1) The curve range in the u-axis direction is consistent.

[0089] like Figure 5 As shown, the endpoints and midpoints of the current u-axis curve interval are obtained as three-dimensional points p1, p2, and p3 on the swept surface. The chord height distance h between point p3 and the chord lengths between p1 and p2 is calculated, and it is determined whether the chord height h is within a preset tolerance range, such as whether h <= 0.001. If not, the current u-axis curve interval is further subdivided into multiple sub-curve intervals. The above judgment is repeated in each sub-curve interval until the chord height h is within the preset tolerance range. After the recursive judgment is completed, a series of discrete points of the u-axis curve interval division can be obtained, which is the u-axis position coordinate distribution of the isoparametric line.

[0090] Extract the current swept surface TS from the discrete points of each interval on the shaped swept surface. ij TS i(j+1) The isoparametric lines make the shaped swept surface TS ij and the shaped swept surface TS i(j+1) There are the same number of isoparametric lines.

[0091] The preset tolerance determines the accuracy of the intersection line of the sweep feature transition region. It is controlled by the user. The smaller the preset tolerance, the higher the accuracy of the surface intersection line.

[0092] Step 4: Generate the surface intersection line by fitting the intersection of the isoparametric lines.

[0093] S1. Based on the u-axis position coordinates of all isoparametric lines of the shaped swept surface obtained in step 3, establish isoparametric lines on two adjacent shaped swept surfaces. Take two isoparametric lines on adjacent shaped swept surfaces with the same u-axis position coordinates (adjacent on the two shaped swept surfaces respectively) as two adjacent isoparametric lines and find the intersection point between the two adjacent isoparametric lines. That is, since the two adjacent path curves are coplanar, the two adjacent isoparametric lines will have an intersection point. Find the intersection point.

[0094] S2. There may be one or more solutions when finding the intersection of curves. The number of intersection points should be judged and processed accordingly.

[0095] As can be seen from the third step, in each swept splicing area, the formed swept surface TS ij TS i(j+1) Their respective isoparametric lines have been generated. The swept surface TS will be shaped. ij Each isoparametric line and its corresponding shape on the swept surface TS i(j+1) Intersect the isoparametric lines in the curve to obtain one or more intersection points.

[0096] The specific steps are as follows:

[0097] If there is only one intersection point between two adjacent isoparametric lines, then the intersection point is retained as a legal intersection point and as a valid intersection point.

[0098] If there are only two intersection points between two adjacent isoparametric lines, and multiple intersection points exist, then the optimal intersection point is selected by combining the tangential vector with the three-dimensional position.

[0099] S21. Extract the path tangent vectors v of the two path curves corresponding to two adjacent isoparametric lines at the path connection point using computer calculation. c1 and v c2 , the tangent vectors of the two paths v c1 and v c2 Performing a cross product yields the first reference normal N1;

[0100] S22. Traverse each intersection point between two adjacent isoparametric lines, extract the intersection tangent vectors v1 and v2 of the two adjacent isoparametric lines at each intersection point through computer calculation, and perform a cross product of the two intersection tangent vectors v1 and v2 to obtain the second reference normal N2.

[0101] S23. Retain the intersection points where the first reference normal N1 and the second reference normal N2 are the same as candidate intersection points;

[0102] S24. Finally, the following judgments and processing are performed on the candidate intersection points:

[0103] If only one intersection point is retained, then that intersection point is the optimal intersection point.

[0104] If there are multiple intersection points to retain, the intersection point that is closest in three dimensions to the path connection point between the two path curves corresponding to the two adjacent isoparametric lines is taken as the optimal intersection point.

[0105] Finally, if there are multiple candidate intersection points after filtering, select the candidate point closest to the connection point of the path curve as the valid intersection point.

[0106] After the overall calculation is completed, a series of intersection points are obtained. These intersection points are fitted with a spline curve to obtain a fitted intersection line. This intersection line serves as the surface intersection line in the current sweep feature transition region, such as... Figure 6 As shown.

[0107] like Figure 7 As shown, P represents a closed-loop sweep profile, and C1 and C2 represent two path curves, respectively.

[0108] The sweep profile P is swept along two path curves C1 and C2.

[0109] like Figure 8 As shown, there are multiple intersection points when isoparametric lines intersect. Taking the contour shape curve P8 of the 8th sweep profile as an example, a sweep surface is generated along the path curves C1 and C2 of the sweep path. When processing the transition region from path curve C1 to path curve C2, adjacent isoparametric lines IsoCurve... 8-1 and IsoCurve 8-2 After finding the intersection, we obtain two intersection points IntP1 and IntP2. The tangents of C1 and C2 at the connection point are v and v, respectively. c1 v c2 The corresponding first reference normal N points downwards; the tangents of the other two intersection points on the two isoparametric lines are v. 1-1 v 2-1 and v 1-2 v 2-2 The second reference normal v of the two intersection points on the isoparametric line can be calculated. 3-1 Opposite to N, second reference normal v 3-2 If the direction is the same as N, then the corresponding intersection point to be retained is IntP2.

[0110] S3. Thus, an intersection point is obtained between each pair of adjacent isoparametric lines. Then, the existing spline curve fitting algorithm is used to fit all the intersection points to obtain a new fitted intersection line. The fitted intersection line is used as the surface intersection line between two shaped swept surfaces for subsequent model generation.

[0111] Step 5: Boundary sweeping.

[0112] The topology of the sweep model is constructed by using the intersection lines of the surfaces to cut and splice each pair of adjacent swept surfaces, and using the boundaries of the swept surfaces and the fitted intersection lines obtained in the fourth step as topological edges.

[0113] Then, check each swept surface for geometric degradation scenarios and perform geometric degradation operations to form a valid CAD swept model from the final shaped swept surfaces.

[0114] Check each swept surface for geometric degradation scenarios, such as faces degenerating into lines or edges degenerating into points. This can be achieved by deleting topological faces and adding topological edges, or deleting topological edges and adding topological points. If such scenarios exist, mark the current edge as a degenerate edge and the current face as a degenerate face to ensure the topology of the CAD swept model is valid.

[0115] like Figure 9 As shown, the sweep result of sweep profile P1 along sweep path C2 includes two points where the sweep edge degenerates and the sweep surface degenerates into a line. The current degenerate edge and degenerate surface are marked, and the topology is adjusted to ensure the topological validity of the sweep model.

[0116] It should be noted that the sweep edge corresponding to the v-axis direction of the swept surface may be a curve that degenerates into a point. When there are multiple curves that degenerate into points, there may also be a degenerate surface.

[0117] Example 2 is as follows:

[0118] like Figure 10 The image shows another example, which is a swept surface and model formed by sweeping a closed-loop swept profile along two S-shaped extended path curves.

[0119] Comparative example:

[0120] According to such Figure 11 The sweeping component 1 and shown Figure 12 The sweeping component 2 shown was fully processed using both the method of this invention and the conventional OCCT method, and the results are as follows:

[0121] Table 1 Comparison of sweeping component time

[0122] OCCT method time (ms) The time taken by the method of this invention (ms) Performance improvement factor Sweep component 1 46.5 10.5 3.4 Sweep component 2 28.7 7.1 3.0

[0123] In the table above, the performance improvement factor is calculated as: (OCCT method time - Invention method time) / Invention method time.

[0124] The isoparametric line intersection method proposed in this invention reduces the computational complexity of intersection lines from surfaces to lines, thereby improving computational stability and accuracy.

[0125] The table above lists the processing times (in ms) for "Sweep Component 1" and "Sweep Component 2" on the OCCT platform and under the method proposed in this invention. It can be seen that "Sweep Component 1" takes 46.5 ms in OCCT, while the method of this invention only requires 10.5 ms; "Sweep Component 2" takes 28.7 ms and 7.1 ms respectively. The results show that the method of this invention can significantly reduce computation time in both test scenarios.

[0126] The above specific embodiments are used to explain and illustrate the present invention, but not to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

[0127] The above description is only a preferred embodiment of the present invention. Therefore, all equivalent changes or modifications made to the structure, features and principles described in the claims of this patent application are included in the scope of this patent application.

Claims

1. A method for processing the swept splicing area of ​​a CAD vector model of a pipe component based on isoparametric line intersection, characterized in that: The method steps are as follows: The first step is to generate the swept surface. In the computer, the sweep profile and sweep path of the pipe component are traversed, and a preliminary sweep surface is generated for each path curve along the sweep profile. The second step is to extend the swept surface. Each initial swept surface is extended to form a shaped swept surface, and a swept splicing area is established between two adjacent shaped swept surfaces; The third step is to adaptively extract isoparametric coordinates. At each swept splicing area, the u-axis position coordinates of the isoparametric lines of the adjacent formed swept surfaces are extracted using a stepped bisection method. The fourth step is to generate the surface intersection line by fitting the intersection of the isoparametric lines. For each swept splicing area, isoparametric lines are established on two adjacent swept surfaces using the u-axis position coordinates of isoparametric lines to find the intersection of curves, and a series of intersection points are obtained and fitted to obtain the surface intersection line. The fourth step is specifically as follows: S1. Based on the u-axis position coordinates of all isoparametric lines of the shaped swept surface obtained in step 3, establish isoparametric lines on two adjacent shaped swept surfaces. Take two isoparametric lines on adjacent shaped swept surfaces with the same u-axis position coordinates as two adjacent isoparametric lines and find the intersection point between the two adjacent isoparametric lines. S2. The following judgment and processing are performed on the number of intersection points to be calculated: If there is only one intersection point, then that intersection point is retained as a valid intersection point; If there are only two intersection points, the optimal intersection point is selected by combining the tangential vector with the three-dimensional position. S3. Use a spline curve fitting algorithm to fit all intersection points to obtain a new fitted intersection line, and use the fitted intersection line as the surface intersection line between two shaped swept surfaces. The process of selecting the optimal intersection point based on the tangential vector and the three-dimensional position is as follows: S21. Extract the path tangent vector v of each of the two path curves corresponding to two adjacent isoparametric lines at the connection point. c1 and v c2 , the tangent vectors of the two paths v c1 and v c2 Performing a cross product yields the first reference normal N1; S22. Traverse each intersection point between two adjacent isoparametric lines, extract the intersection tangent vectors v1 and v2 of the two adjacent isoparametric lines at each intersection point, and perform a cross product of the two intersection tangent vectors v1 and v2 to obtain the second reference normal N2. S23. Retain the same intersection point of the first reference normal N1 and the second reference normal N2; S24. Finally, the following judgments and processes are performed: If only one intersection point is retained, then that intersection point is the optimal intersection point. If there are multiple intersection points to retain, the intersection point that is closest in three dimensions to the connection point between the two path curves corresponding to the two adjacent isoparametric lines is taken as the optimal intersection point. Step 5: Boundary sweeping treatment The intersection lines of the curved surfaces are used to cut and splice two adjacent shaped swept surfaces. Then, each swept surface is checked for geometric degradation and geometric degradation is performed. The final shaped swept surfaces form a CAD swept model.

2. The method for processing the swept splicing area of ​​a CAD vector model of a pipe component based on isoparametric line intersection as described in claim 1, characterized in that: The sweep profile is a contour curve, and the sweep path is mainly composed of multiple coplanar different path curves connected end to end in sequence.

3. The method for processing the swept splicing area of ​​a CAD vector model of a pipe component based on isoparametric line intersection as described in claim 1, characterized in that: The second step is as follows: for each preliminary swept surface, extend the surface along the tangential direction at both ends of its own path curve to obtain the shaped swept surface; the shaped swept surfaces generated by every two adjacent path curves intersect, and the area at the intersection is used as the swept splicing area.

4. The method for processing the swept splicing area of ​​a CAD vector model of a pipe component based on isoparametric line intersection as described in claim 1, characterized in that: The third step specifically involves: T1. Initially, the entire swept profile is considered as a curve interval along the u-axis. T2. For each curve interval along the u-axis, along the u-axis, take the two endpoints and the midpoint of the curve interval along the u-axis, establish the line connecting the two endpoints as the chord length, and calculate the vertical distance from the midpoint to the chord length as the chord height. T3. Determine if the chord height is within the preset tolerance value and proceed accordingly: If the chord height is within the preset tolerance, the process ends; If the chord height is not within the preset tolerance, the current U-axis curve interval is subdivided in a binary manner, that is, the original U-axis curve interval is divided into two U-axis curve intervals. T4. Return to step T2 above, and repeat T2~T3 for processing until the chord height of each curve interval in the u-axis direction is within the preset tolerance. T5. The distribution of all current curve intervals along the u-axis is used as the distribution of isoparametric lines, and the coordinate parameters of the boundary points between adjacent curve intervals along the u-axis are used as the u-axis position coordinates of the isoparametric lines.

5. The method for processing the swept splicing area of ​​a CAD vector model of a pipe component based on isoparametric line intersection as described in claim 1, characterized in that: The computer used is a personal computer, FPGA, microcontroller, etc.

6. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 5.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 5.

Images