A three-dimensional winding path generation method and system based on outer contour expansion effect
By setting a sampling surface on the surface of the core mold and combining differential geometry and convex hull algorithm to design the expansion winding path, the problem of yarn deviation caused by the expansion of the outer contour during the winding process is solved, and stable and efficient three-dimensional winding path generation is achieved, which is suitable for the winding design of various core molds.
Patent Information
- Application Number
- CN202210926068.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-08-03
- Publication Date
- 2025-09-16
- Estimated Expiration
- 2042-08-03
AI Technical Summary
The existing winding path planning fails to effectively consider the yarn drop offset and part outer contour deviation caused by the outer contour expansion effect during the winding process, resulting in interruption of the winding process and part defects.
A three-dimensional winding path generation method based on the outer contour expansion effect is adopted. By setting uniformly arranged sampling surfaces on the surface of the core mold, combined with differential geometry theory and convex hull algorithm, an expanded winding path is designed, and the sampling surfaces are updated and smoothed. The influence of yarn width and height is considered to ensure the stability and accuracy of the winding process.
It effectively avoids yarn doffing deviation, improves the reliability of the winding process and the geometric shape accuracy of the workpiece, is suitable for the three-dimensional winding path design of various core molds, and can predict the wall thickness distribution.
Smart Images
Figure CN115438464B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of automated machining technology, and in particular to a method and system for generating a three-dimensional winding path based on an outer contour expansion effect. Background Art
[0002] Filament winding technology is the earliest developed and most widely used automated processing technology. Compared with other production processes, the winding rules of fiber-wound composite products can be designed according to the structural characteristics and stress conditions of the product, which can give full play to the strength of the fiber and has the characteristics of neat fiber arrangement and high accuracy. It has been widely used in aerospace and civil industries, such as rocket engine casings, aircraft fuselages, aircraft engine blades, blade rings and casings, automotive fuel cylinders, medical oxygen cylinders, oil and gas storage tanks and pipelines, etc.
[0003] Winding path planning involves designing the doffing trajectory of the yarn onto the core mold using a specific mathematical algorithm. Improper winding path planning can lead to unfavorable factors such as yarn slippage and bridging during the winding process, which can create defects such as resin-rich areas within the part and even hinder subsequent winding. Therefore, ensuring that the yarn is smoothly laid onto the core mold surface according to the predetermined doffing trajectory is a critical issue that needs to be addressed in current fiber winding technology.
[0004] Existing winding path trajectory algorithms typically use geodesic, semi-geodesic, surface spline, and other non-geodesic paths to design the winding trajectory. These algorithms treat the tape as a geometric curve without width and thickness information, and all path planning processes are performed based on the original mandrel surface. Consequently, existing algorithms ignore the part contour expansion effect caused by the continuous accumulation of tape on the mandrel surface during the winding process. Practical winding experience shows that this contour expansion effect can cause the actual doffing point to deviate from the designed value. Furthermore, this contour expansion effect is uneven, particularly pronounced in the winding turning area or at the end cap, causing the part contour to deviate significantly from the original mandrel surface. In such cases, if the winding path designed based on the initial mandrel surface is still used, the tape can easily slip from the part surface, leading to interruption of the winding process and unavailability of the subsequent designed path, ultimately wasting the entire winding process. Therefore, considering the tape thickness during the path design process to reflect the tape accumulation on the mandrel and designing the subsequent winding path based on the real-time expanded part contour can help address these issues and ensure the process feasibility of the designed path. Summary of the Invention
[0005] In order to fully consider the influence of the physical properties of the tape on the winding effect in the design of the tape winding path, the present invention proposes a three-dimensional winding path generation method based on the outer contour expansion effect, wherein, in the unwound state, the core mold surface is provided with a sampling surface composed of evenly arranged sampling points, which specifically includes the following steps:
[0006] S1: According to the initial slip coefficient and differential geometry theory, the initial winding path on the current sampling surface is obtained under the winding mechanical stability condition;
[0007] S2: Obtaining an expanded winding path by performing an offset process on the initial winding path at a preset width and a preset height;
[0008] S3: Projecting the gauze onto the current sampling surface according to the expansion winding path, and obtaining the sampling points covered by the gauze according to the geometric projection relationship;
[0009] S4: superimposing and updating the height information of the sampling points covered by the yarn tape according to the preset height, and obtaining an updated sampling surface according to the sampling point set with updated height;
[0010] S5: Determine whether the number of winding layers of the current winding path reaches the preset number of layers. If so, proceed to step S6. If not, increase the number of winding layers by one and return to step S1.
[0011] S6: Obtain the actual slip coefficient based on the final overall expansion winding path, and determine whether it is greater than the maximum static friction coefficient of the core mold surface. If so, adjust the initial slip coefficient and return to step S1. If not, output the program code corresponding to the overall expansion winding path.
[0012] Furthermore, in the step S1, the winding mechanical stability conditions include no bridging, no slippage and full coverage during the winding process of the yarn.
[0013] Furthermore, in the step S2, the preset width is the width of the yarn after it is flattened, and the preset height is the height of the yarn after it is flattened.
[0014] Furthermore, in step S2, the expanded winding path is represented by a discrete point set, and each discrete point is arranged equidistantly with preset row and column intervals.
[0015] Furthermore, the step S4 further includes the following steps:
[0016] S41: Based on the convex hull algorithm, a polygon consisting of several discrete points that can surround all discrete points is selected from the discrete point set;
[0017] S42: Smoothing the updated sampling surface according to the selected discrete points.
[0018] The present invention also proposes a three-dimensional winding path generation system based on the outer contour expansion effect, wherein, in the unwound state, the core mold surface is provided with a sampling surface composed of uniformly arranged sampling points, specifically including:
[0019] A path planning module is used to obtain the initial winding path on the current sampling surface under the winding mechanical stability condition according to the initial slip coefficient and differential geometry theory;
[0020] A path expansion module is used to obtain an expanded winding path by performing an offset process on the initial winding path at a preset width and a preset height;
[0021] A coverage statistics module is used to project the yarn onto the current sampling surface according to the expansion winding path, and obtain the sampling points covered by the yarn according to the geometric projection relationship;
[0022] A sampling surface updating module is used to superimpose and update the height information of the sampling points covered by the yarn tape according to a preset height, and obtain an updated sampling surface based on the sampling point set with updated height;
[0023] The slip determination module is used to obtain the actual slip coefficient based on the overall expanded winding path finally obtained when the number of winding layers reaches a preset number of layers, and to re-obtain the overall expanded winding path by adjusting the initial slip coefficient when the actual slip coefficient is greater than the maximum static friction coefficient of the core mold surface, and to output the program code corresponding to the overall expanded winding path when the actual slip coefficient is less than or equal to the maximum static friction coefficient of the core mold surface.
[0024] Furthermore, in the path planning module, the winding mechanical stability conditions include no bridging, no slippage and full coverage during the winding process of the yarn.
[0025] Furthermore, in the path expansion module, the preset width is the width of the flattened ribbon, and the preset height is the height of the flattened ribbon.
[0026] Furthermore, in the path expansion module, the expanded winding path is represented by a discrete point set, and each discrete point is arranged equidistantly with preset row and column intervals.
[0027] Furthermore, the sampling plane updating module further includes:
[0028] The smoothing processing unit is used to screen out a polygon consisting of several discrete points that can surround all discrete points from the discrete point set according to the convex hull algorithm, and to perform smoothing processing on the updated sampling surface according to the screened discrete points.
[0029] Compared with the prior art, the present invention has at least the following beneficial effects:
[0030] (1) The method and system for generating a three-dimensional winding path based on the outer contour expansion effect described in the present invention fully considers the influence of the width and height of the yarn itself on the winding effect during the design of the three-dimensional winding path of the yarn tape, and obtains the expanded winding path under the sampling surface update, thereby effectively avoiding the yarn drop deviation caused by the outer contour expansion;
[0031] (2) The updated sampling surface is smoothed based on the convex hull algorithm, so that the path design based on the sampling surface is more consistent with the yarn winding characteristics in the actual winding process;
[0032] (3) Since the winding path design is updated accordingly with the sampling surface, it can be applied to the three-dimensional winding path design of various core molds;
[0033] (4) Since the sampling surface is updated by thickness stacking, it is beneficial to predict the wall thickness distribution and final geometric shape of the wound part. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] Figure 1 A step diagram of a three-dimensional winding path generation method based on an outer contour expansion effect;
[0035] Figure 2 A structural diagram of a three-dimensional winding path generation system based on the outer contour expansion effect;
[0036] Figure 3 A schematic diagram of the shape of a cut portion of the gauze tape;
[0037] Figure 4 This is a schematic diagram of the overlapping part of the yarn before smoothing;
[0038] Figure 5 This is a schematic diagram of the overlapping part of the yarn after smoothing treatment;
[0039] Figure 6 Schematic diagram of a yarn-tape-wound product based on a core mold design. DETAILED DESCRIPTION
[0040] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.
[0041] Example 1
[0042] In order to design the yarn winding path to be more in line with the physical characteristics of the actual winding process and avoid the yarn deviation caused by not considering the outer contour expansion effect, such as Figure 1The present invention proposes a three-dimensional winding path generation method based on the outer contour expansion effect. In the path design process, sampling points are evenly arranged on the surface of the core mold, and these sampling points together constitute a sampling surface. The specific path generation steps include:
[0043] S1: According to the initial slip coefficient and differential geometry theory, the initial winding path on the current sampling surface is obtained under the winding mechanical stability condition;
[0044] S2: Obtaining an expanded winding path by performing an offset process on the initial winding path at a preset width and a preset height;
[0045] S3: Projecting the gauze onto the current sampling surface according to the expansion winding path, and obtaining the sampling points covered by the gauze according to the geometric projection relationship;
[0046] S4: superimposing and updating the height information of the sampling points covered by the yarn tape according to the preset height, and obtaining an updated sampling surface according to the sampling point set with updated height;
[0047] S5: Determine whether the number of winding layers of the current winding path reaches the preset number of layers. If so, proceed to step S6. If not, increase the number of winding layers by one and return to step S1.
[0048] S6: Obtain the actual slip coefficient based on the final overall expansion winding path, and determine whether it is greater than the maximum static friction coefficient of the core mold surface. If so, adjust the initial slip coefficient and return to step S1. If not, output the program code corresponding to the overall expansion winding path.
[0049] In the path design method proposed in the present invention, it is similar to the traditional winding path design method at the beginning, and the path is processed as a geometric curve without width and thickness. However, the difference is that the present invention designs the initial winding path under the current winding layer based on the current sampling surface, rather than just always based on the core mold surface. Then, according to the winding mechanical stability conditions, the winding path is designed by geodesics, semi-geodesics, pseudo-geodesics, surface splines, and triangular patch methods under the conditional constraints of the initial slip coefficient. Among them, the winding mechanical stability conditions include no bridging, no slip, and full coverage, ensuring that the core mold is evenly covered by the yarn. In other words, for different sampling surfaces, the winding paths obtained by design are different. In the present invention, this difference is the path design adaptability optimization for the outer contour expansion effect, and the specific optimization means are as follows.
[0050] First, considering that the yarn itself has a certain width and height (such as Figure 3(See the figure for a schematic diagram of a section of the yarn tape.) As the yarn is wound onto the core mold, the resulting workpiece diameter inevitably increases with the number of winding layers. Therefore, to account for this change in the winding path design, the present invention proposes offsetting the initial winding path in both the width and height directions based on the target winding yarn's width and height information, thereby obtaining an expanded winding path.
[0051] Then, based on the obtained expansion winding path, the tape is simulated to cover the current sampling surface. That is, the tape is gradually projected onto the current sampling surface according to the expansion winding path. The sampling points covered by the tape are then extracted based on the geometric projection relationship. The extraction of sampling points covered by the tape is based on the consideration of the impact of the tape's own height on the outer surface morphology of the workpiece, which is composed of the next layer of sampling surface. The specific optimization is as follows: based on a preset height set based on the tape's own parameters (that is, the height of the tape after flattening, or the thickness of the tape), as the tape is gradually projected onto the current sampling surface according to the expansion winding path, the height information of these sampling points is updated based on the extracted covered sampling points (based on the current height, a preset height is superimposed on the height information of the covered sampling points each time the tape is covered).
[0052] In this way, as the height information of each sampling point is updated and iterated, the sampling surface composed of the sampling point set will also be updated. In other words, as the number of yarn winding layers increases, the initial winding path obtained based on the updated sampling surface will also be adaptively optimized.
[0053] The above description dynamically describes the process of tape stacking on the workpiece surface from step S1 to step S4, and there is no geometric interference between the tapes. However, the tape winding trajectory obtained by the above improvement alone still has some shortcomings. This is because the above steps are based on the assumption that the new tape is always close to the core mold or the previous layer of tape. Therefore, the winding path obtained based on this assumption will result in wrinkles at the intersection of the two tapes (such as Figure 4 In the actual winding process, the yarn is stretched and straightened under the winding tension (as shown in Figure 5 Therefore, the path at the intersection of the yarns does not conform to the actual situation and needs further optimization.
[0054] To address the wrinkle problem, the present invention utilizes the principle of the convex hull algorithm. First, the expanded winding path is represented as a set of discrete points arranged in preset rows and columns with equal spacing. Then, a polygon consisting of these discrete points is selected from the set of discrete points. It should be noted that this polygon must have the smallest area while containing all the discrete points (i.e., convex point selection). The polygon obtained by this method is the sampling surface after smoothing.
[0055] The above method is used to design and optimize the winding path of the yarn layer by layer, and after reaching the preset number of layers, the overall expansion winding path is obtained. In order to further ensure that the winding path finally obtained can guarantee the reliability after being put into production, the actual slip coefficient of the overall expansion winding path finally obtained is calculated. Only when it is less than or equal to the maximum static friction coefficient of the core mold surface, the path will be output to the CNC winding machine with the corresponding program code. According to the program code, the CNC winding machine can be controlled to wind the yarn (such as Figure 6 (The figure shows a product made by winding a yarn based on a core mold design). When the actual slip coefficient is greater than the maximum static friction coefficient of the core mold surface, it means that the designed winding path cannot firmly fix the yarn to the core mold surface, and there is a risk of slippage. Therefore, it is necessary to redesign the winding path by adjusting the initial slip coefficient (generally lowering it).
[0056] Example 2
[0057] In order to better understand the technical content of the present invention, this embodiment describes the present invention in the form of a system structure. Figure 2 As shown, a three-dimensional winding path generation system based on the outer contour expansion effect is provided. In the unwound state, the core mold surface is provided with a sampling surface composed of uniformly arranged sampling points, specifically including:
[0058] A path planning module is used to obtain the initial winding path on the current sampling surface under the winding mechanical stability condition according to the initial slip coefficient and differential geometry theory;
[0059] A path expansion module is used to obtain an expanded winding path by performing an offset process on the initial winding path at a preset width and a preset height;
[0060] A coverage statistics module is used to project the yarn onto the current sampling surface according to the expansion winding path, and obtain the sampling points covered by the yarn according to the geometric projection relationship;
[0061] A sampling surface updating module is used to superimpose and update the height information of the sampling points covered by the yarn tape according to a preset height, and obtain an updated sampling surface based on the sampling point set with updated height;
[0062] The slip determination module is used to obtain the actual slip coefficient based on the overall expanded winding path finally obtained when the number of winding layers reaches a preset number of layers, and to re-obtain the overall expanded winding path by adjusting the initial slip coefficient when the actual slip coefficient is greater than the maximum static friction coefficient of the core mold surface, and to output the program code corresponding to the overall expanded winding path when the actual slip coefficient is less than or equal to the maximum static friction coefficient of the core mold surface.
[0063] Furthermore, in the path planning module, the winding mechanical stability conditions include no bridging, no slippage and full coverage during the tape winding process.
[0064] Furthermore, in the path expansion module, the preset width is the width of the yarn after it is flattened, and the preset height is the height of the yarn after it is flattened.
[0065] Furthermore, in the path expansion module, the expanded winding path is represented by a discrete point set, and each discrete point is arranged equidistantly with preset row and column intervals.
[0066] Furthermore, the sampling surface update module further includes:
[0067] The smoothing processing unit is used to screen out a polygon consisting of several discrete points that can surround all discrete points from the discrete point set according to the convex hull algorithm, and to perform smoothing processing on the updated sampling surface according to the screened discrete points.
[0068] In summary, the method and system for generating a three-dimensional winding path based on the contour expansion effect described in the present invention fully considers the influence of the tape's width and height on the winding effect during the three-dimensional winding path design process. This method acquires the expanded winding path with an updated sampling surface, effectively avoiding the doffing offset caused by contour expansion. The updated sampling surface is smoothed using a convex hull algorithm, ensuring that the path design based on the sampling surface is more consistent with the tape winding characteristics during the actual winding process.
[0069] Since the winding path design is updated accordingly with the sampling surface, it can be applied to the three-dimensional winding path design of various core molds. Since the sampling surface is updated by thickness stacking, it is helpful to predict the wall thickness distribution of the wound part and the final geometric shape.
[0070] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.
[0071] In addition, in the present invention, descriptions such as "first," "second," and "one" are for descriptive purposes only and should not be understood to indicate or imply their relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.
[0072] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on specific circumstances.
[0073] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.
Claims
1. A three-dimensional winding path generation method based on outer contour expansion effect, characterized in that: In the unwound state, the surface of the core mold is provided with a sampling surface consisting of evenly arranged sampling points, which specifically includes the following steps: S1: Based on the initial slip coefficient and differential geometry theory, the initial winding path on the current sampling surface is obtained under the winding mechanical stability condition; S2: Obtain an expanded winding path by performing an offset process on the initial winding path at a preset width and a preset height; In the step S2, the preset width is the width of the flattened ribbon, and the preset height is the height of the flattened ribbon; S3: Projecting the gauze onto the current sampling surface according to the expansion winding path, and obtaining the sampling points covered by the gauze according to the geometric projection relationship; S4: superimposing and updating the height information of the sampling points covered by the yarn tape according to the preset height, and obtaining an updated sampling surface according to the sampling point set with updated height; The S4 step further includes the following steps: S41: Based on the convex hull algorithm, a polygon consisting of several discrete points that can surround all discrete points is selected from the discrete point set; S42: performing smoothing processing on the updated sampling surface according to the selected discrete points; S5: Determine whether the number of winding layers of the current winding path reaches the preset number of layers. If so, proceed to step S6. If not, increase the number of winding layers by one and return to step S1. S6: Obtain the actual slip coefficient based on the final overall expansion winding path, and determine whether it is greater than the maximum static friction coefficient of the core mold surface. If so, adjust the initial slip coefficient and return to step S1. If not, output the program code corresponding to the overall expansion winding path.
2. A three-dimensional winding path generation method based on outer contour expansion effect as claimed in claim 1, characterized in that: In the step S1, the winding mechanical stability conditions include no bridging, no slippage and full coverage during the winding process of the yarn.
3. The method for generating a three-dimensional winding path based on an outer contour expansion effect according to claim 1, wherein: In the step S2, the expanded winding path is represented by a discrete point set, and each discrete point is arranged equidistantly at preset row and column intervals.
4. A three-dimensional winding path generation system based on outer contour expansion effect, characterized in that: In the unwound state, the surface of the mandrel is provided with a sampling surface consisting of evenly arranged sampling points, specifically including: A path planning module is used to obtain the initial winding path on the current sampling surface under the winding mechanical stability condition according to the initial slip coefficient and differential geometry theory; A path expansion module is used to obtain an expanded winding path by performing an offset process on the initial winding path at a preset width and a preset height; In the path expansion module, the preset width is the width of the flattened ribbon, and the preset height is the height of the flattened ribbon; A coverage statistics module is used to project the yarn onto the current sampling surface according to the expansion winding path, and obtain the sampling points covered by the yarn according to the geometric projection relationship; A sampling surface updating module is used to superimpose and update the height information of the sampling points covered by the yarn tape according to a preset height, and obtain an updated sampling surface based on the sampling point set with updated height; The sampling plane updating module further includes: A smoothing processing unit is used to screen out a polygon consisting of several discrete points that can surround all discrete points from the discrete point set according to a convex hull algorithm, and to perform smoothing processing on the updated sampling surface according to the screened discrete points; The slip determination module is used to obtain the actual slip coefficient based on the overall expanded winding path finally obtained when the number of winding layers reaches a preset number of layers, and to re-obtain the overall expanded winding path by adjusting the initial slip coefficient when the actual slip coefficient is greater than the maximum static friction coefficient of the core mold surface, and to output the program code corresponding to the overall expanded winding path when the actual slip coefficient is less than or equal to the maximum static friction coefficient of the core mold surface.
5. The three-dimensional winding path generation system based on the outer contour expansion effect according to claim 4, characterized in that: In the path planning module, the winding mechanical stability conditions include no bridging, no slippage and full coverage during the yarn winding process.
6. The three-dimensional winding path generation system based on the outer contour expansion effect according to claim 4, characterized in that: In the path expansion module, the expanded winding path is represented by a discrete point set, and each discrete point is arranged equidistantly with preset row and column intervals.