Digital lofting method for hull curved surface machining template
By digitally processing the hull surface, calculating the unidirectional main twist direction, and generating digital template files, the problem of controlling the angle of the hull curved panel processing template was solved, achieving efficient and precise processing and management.
Patent Information
- Application Number
- CN202610226317.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-26
- Publication Date
- 2026-05-26
AI Technical Summary
In shipbuilding, the angle control of the processing templates for the curved hull panels is difficult and arbitrary, resulting in uncontrollable precision, easy rework, and low work efficiency.
By acquiring a three-dimensional digital model of the target hull surface, calculating the unidirectional main twist direction, defining a parallel cutting plane with an angle of 85 to 95 degrees to this direction, setting the plane interval, calculating the intersection line, and generating a digital template file, digital and automated lofting is achieved.
It reduces human error, improves processing accuracy and efficiency, lowers template making and management costs, and is suitable for processing complex and simple curved surfaces.
Smart Images
Figure CN122088099A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of shipbuilding technology, specifically to a digital lofting method for machining hull curved surfaces using templates. Background Technology
[0002] In shipbuilding, the outer plating of the bow, stern, and part of the bilge often has complex spatial curved surface shapes, many of which exhibit "unidirectional twisting" characteristics (i.e., the surface normal is systematically deflected in a certain dominant direction). The precise forming of such surfaces is a challenge in the construction process.
[0003] Traditional ship hull curved panel processing templates are made using the rib profile data. When checking the processing profile, the template and the processing plate will form a certain angle. This angle is related to the twist of the curved panel. The template must be kept at a certain angle to check the accurate profile.
[0004] However, the angle control during sample inspection is difficult, arbitrary, and the processing accuracy is uncontrollable. Errors in the sample angle can easily lead to rework, wasting time and resulting in low work efficiency.
[0005] Based on this, the present invention designs a digital lofting method for machining templates of ship hull curved surfaces to solve the above problems. Summary of the Invention
[0006] The purpose of this invention is to provide a digital lofting method for machining templates of ship hull curved surfaces, so as to solve the above-mentioned technical problems.
[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for digital lofting of a template for machining curved surfaces of a ship hull, characterized by comprising the following steps: S1. Model Acquisition and Direction Analysis: Acquire a three-dimensional digital model of the target hull surface, and calculate and determine the unidirectional main twist direction of the surface based on the model; S2. Definition of Cutting Plane Group: Define a set of virtual parallel cutting planes, wherein the angle between the common normal direction of the set of cutting planes and the unidirectional twisting main direction determined in step S1 is between 85 degrees and 95 degrees. S3. Plane spacing setting: Along the length of the ship, the spacing between each plane in the set of parallel cutting planes is determined according to a preset rule; S4. Curve Calculation and Extraction: In the three-dimensional digital model, the intersection line between each parallel cutting plane and the target hull surface is calculated to obtain a set of spatial curves, and the three-dimensional coordinate data of each spatial curve is extracted. S5. Template Data Generation: Based on the three-dimensional coordinate data, generate a digital template file for driving the processing equipment to make physical processing templates or for direct use in steel plate forming inspection.
[0008] By adopting the above technical solution, it is ensured that the cutting direction is perpendicular to the main trend of surface deformation, thereby enabling the extraction of the key profile that best controls the twisting shape of the board and reducing the error of manual drawing and layout.
[0009] Preferably, in step S1, the specific method for determining the unidirectional main twist direction includes: S1.1 On the target hull surface of the three-dimensional digital model, select a series of sampling points along the length of the ship; S1.2 Calculate the surface normal vector at each sampling point; S1.3 Analyze the trend of the change of the direction angle of the series of surface normal vectors on the horizontal projection plane, calculate its dominant direction by statistical or fitting methods, and define the dominant direction as the unidirectional twisting main direction.
[0010] By adopting the above technical solution, a specific, objective, repeatable and computationally stable technical means is provided to determine the main direction of distortion. The algorithm utilizes the differential geometry of the surface, and the results are accurate and reliable. It does not rely on human visual experience, thus ensuring the consistency of the whole method and its universality in application on different surfaces.
[0011] Preferably, in step S3, the preset rule is: the interval position of the parallel cutting plane is set to be consistent with the rib position of the hull structure.
[0012] By adopting the above technical solution, the generated processing template is naturally aligned with the actual structural frame (ribs) of the ship. When positioning, inspecting and assembling steel plates, the template reference is clear, which facilitates quick understanding and operation on site.
[0013] Preferably, in step S3, the preset rule is: to adaptively adjust according to the curvature change of the target hull surface in the length direction, reduce the cutting plane interval in the region where the curvature change rate is greater than a preset threshold, and increase the cutting plane interval in the region where the curvature change is gentle.
[0014] By adopting the above technical solution, the cutting is automatically densified in areas with complex curved shapes (large curvature changes), ensuring precise control over complex shapes; the spacing is automatically widened in flat areas, reducing unnecessary templates.
[0015] Preferably, in step S3, the preset rule is: the parallel cutting planes are arranged at equal intervals along the length of the ship.
[0016] By adopting the above technical solution, it is applicable to the rapid prototyping of relatively uniform curved surfaces and the early roughing or preforming stages, demonstrating the flexibility of the method.
[0017] Preferably, in step S2, the common normal direction is perpendicular to the unidirectional twisting main direction.
[0018] By adopting the above technical solution, the cut profile can most directly and effectively constrain the torsional deformation of the sheet metal. The template made in this way provides the clearest and most effective feedback when guiding workers to use the template for bending operations. It can minimize trial and error and correction, and is the ideal mode to achieve the highest processing accuracy and efficiency.
[0019] Preferably, in step S5, generating the digital template file includes: converting the three-dimensional coordinate data into two-dimensional planar unfolded data, and outputting it as a code file or standard graphic file that can be read by a CNC cutting machine.
[0020] By adopting the above technical solution, the design data is directly converted into executable manufacturing instructions. The data can be directly imported into a laser projector to project the theoretical profile onto the steel plate for real-time comparison.
[0021] In summary, this application has the following beneficial technical effects: by identifying and cutting perpendicular to the main direction of surface twist, the obtained profile best conforms to the natural extension direction of the surface, enabling the processing template made accordingly to more accurately control the bending and twisting of the steel plate, significantly reducing forming errors and subsequent finishing work. The method is based on automatic calculation of a three-dimensional model, realizing the digitalization and automation of the layout process, reducing reliance on skilled workers. At the same time, due to the better template orientation, fewer templates can usually be used to achieve the same or even higher control accuracy, reducing the cost of template production and management. Attached Figure Description
[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0023] Figure 1 This is a flowchart of the digital lofting method for machining ship hull curved surfaces according to the present invention. Detailed Implementation
[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0025] The following is in conjunction with the appendix Figure 1 This application will be described in further detail.
[0026] A method for digitally lofting a template for machining curved surfaces of a ship's hull includes the following steps: S1. Model Acquisition and Direction Analysis: Acquire a three-dimensional digital model of the target hull surface, calculate and determine the unidirectional torsion principal direction of the surface based on the model; select a series of sampling points along the ship length direction on the target hull surface of the three-dimensional digital model, calculate the surface normal vector at each sampling point, analyze the trend of the direction angle change of the series of surface normal vectors on the horizontal projection plane, calculate its dominant direction through statistical or fitting methods, and define the dominant direction as the unidirectional torsion principal direction; S2. Definition of Cutting Plane Group: Define a set of virtual parallel cutting planes, wherein the common normal direction of the set of cutting planes is perpendicular to the unidirectional twisting main direction; S3. Plane Spacing Setting: Along the ship's length, the spacing between each plane in the set of parallel cutting planes is determined according to a preset rule. The plane spacing setting is to align the spacing of the parallel cutting planes with the hull structure ribs. S3.2. Adaptive adjustment is made based on the curvature change of the target hull surface along the ship's length. In areas where the rate of curvature change is greater than a preset threshold, the cutting plane spacing is reduced; in areas where the curvature change is gradual, the cutting plane spacing is increased. S3.3. The parallel cutting planes are arranged at equal intervals along the ship's length. S4. Curve Calculation and Extraction: In the three-dimensional digital model, the intersection line between each parallel cutting plane and the target hull surface is calculated to obtain a set of spatial curves, and the three-dimensional coordinate data of each spatial curve is extracted. S5. Template Data Generation: Based on the three-dimensional coordinate data, generate a digital template file for driving the processing equipment to make physical processing templates or for direct use in steel plate forming inspection. Convert the three-dimensional coordinate data into two-dimensional planar unfolded data and output it as a code file or standard graphic file that can be read by a CNC cutting machine.
[0027] In some embodiments, in step S1, an accurate three-dimensional model of the target outer plate surface is exported from a ship design three-dimensional CAD system (such as Tribon, NAPA, CATIA, etc.). On this surface, at least 20 sampling points are uniformly selected along the ship's length direction. Using the CAD system's API or an external mathematical library, the unit normal vector of each point is calculated. All normal vectors are projected onto the horizontal plane (i.e., the ship's waterline) to obtain a series of orientation angles. These orientation angles are fitted using linear regression or principal component analysis (PCA) methods. The direction of the fitted line is the unidirectional twisting principal direction θ of this surface in the current region. This completely replaces the traditional method of manually judging the twisting direction, eliminates human experience errors, and makes the analysis results repeatable and verifiable.
[0028] In some embodiments, in step S2, a set of parallel virtual planes are defined in three-dimensional space. The common normal direction of this set of planes is set to be perpendicular to the θ direction obtained in step S1. In actual operation, the first plane (reference plane) is created in CAD software, and then the plane group is generated by translation and copying. The geometric principle is transformed into directly executable digital instructions, realizing a smooth transition from theory to operable tool.
[0029] In some embodiments, in step S3, this embodiment uses a preset rule corresponding to the rib position to query the rib distance of the hull area, and sequentially translates the reference plane created in step S2 along the ship length direction to the nearest rib line (such as Fr10, Fr11, Fr12...), thereby determining the specific position of all cutting planes, which facilitates on-site workers to quickly and accurately locate and compare on the hull frame or sections.
[0030] In some embodiments, in step S3, the preset rule consistent with the rib position ensures that the generated template is aligned with the actual structural frame (rib) of the hull, facilitating on-site workers' positioning and inspection, and can be seamlessly integrated into the existing shipbuilding process; the preset rule of adaptive spacing can dynamically adjust the accuracy according to the complexity of the curved surface, and may reduce the number of unnecessary templates while ensuring control effect, achieving the best balance between efficiency and accuracy; the preset rule of equal spacing is logically clear, easy to implement, and suitable for curved surfaces with regular shapes and uniform distortion, or preliminary lofting scenarios with extremely high efficiency requirements and slightly lower accuracy requirements.
[0031] In some embodiments, in step S4, the "surface intersection" function of the 3D CAD software is used to sequentially calculate the intersection lines between each cutting plane (located at Fr10, Fr11...) and the target outer plate surface. These intersection lines are the spatial profiles to be obtained. The discrete point coordinate sequence (x, y, z) of each spatial profile is exported as a data file. The data file containing the three-dimensional coordinate sequence is exported, and the geometry is transformed into structured digital information that can be processed by subsequent software.
[0032] In some embodiments, in step S5, since the processing template is usually a flat strip or thin plate, it is necessary to unfold the three-dimensional spatial profile into a two-dimensional plane. According to the position and direction of the cutting plane where each profile is located, its three-dimensional coordinates are converted into two-dimensional coordinates (u, v) in the plane. All two-dimensional profile data are integrated, and after layout, a DXF format file is generated. This file can be transmitted to a CNC laser cutting machine to directly cut out the physical processing template of wood or plastic.
[0033] In the description of this invention, it should be understood that the terms "coaxial," "bottom," "one end," "top," "middle," "other end," "upper," "side," "top," "inner," "front," "center," "both ends," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.
[0034] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," "fixing," "screw connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0035] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for digital lofting of a template for machining curved surfaces of a ship's hull, characterized in that, Includes the following steps: S1. Model Acquisition and Direction Analysis: Acquire a three-dimensional digital model of the target hull surface, and calculate and determine the unidirectional main twist direction of the surface based on the model; S2. Definition of Cutting Plane Group: Define a set of virtual parallel cutting planes, wherein the angle between the common normal direction of the set of cutting planes and the unidirectional twisting main direction determined in step S1 is between 85 degrees and 95 degrees. S3. Plane spacing setting: Along the length of the ship, the spacing between each plane in the set of parallel cutting planes is determined according to a preset rule; S4. Curve Calculation and Extraction: In the three-dimensional digital model, the intersection line between each parallel cutting plane and the target hull surface is calculated to obtain a set of spatial curves, and the three-dimensional coordinate data of each spatial curve is extracted. S5. Template Data Generation: Based on the three-dimensional coordinate data, generate a digital template file for driving the processing equipment to make physical processing templates or for direct use in steel plate forming inspection.
2. The method for digital lofting of a hull surface machining template according to claim 1, characterized in that: In step S1, the specific method for determining the principal direction of unidirectional twisting includes: S1.1 On the target hull surface of the three-dimensional digital model, select a series of sampling points along the length of the ship; S1.2 Calculate the surface normal vector at each sampling point; S1.3 Analyze the trend of the change of the direction angle of the series of surface normal vectors on the horizontal projection plane, calculate its dominant direction by statistical or fitting methods, and define the dominant direction as the unidirectional twisting main direction.
3. The method for digital lofting of a hull surface machining template according to claim 1, characterized in that: In step S3, the preset rule is: the interval position of the parallel cutting plane is set to be consistent with the rib position of the hull structure.
4. The method for digital lofting of a hull surface machining template according to claim 1, characterized in that: In step S3, the preset rule is as follows: adaptive adjustment is made according to the curvature change of the target hull surface in the length direction; in the region where the rate of curvature change is greater than a preset threshold, the cutting plane interval is reduced; in the region where the curvature change is gentle, the cutting plane interval is increased.
5. The method for digital lofting of a hull surface machining template according to claim 1, characterized in that: In step S3, the preset rule is: the parallel cutting planes are arranged at equal intervals along the length of the ship.
6. The method for digital lofting of a hull surface machining template according to claim 1, characterized in that: In step S2, the common normal direction is perpendicular to the unidirectional twisting main direction.
7. The method for digital lofting of a hull surface machining template according to claim 1, characterized in that: In step S5, generating the digital template file includes: converting the three-dimensional coordinate data into two-dimensional planar unfolded data, and outputting it as a code file or standard graphic file that can be read by a CNC cutting machine.