Aviation machining part modeling method based on CATIA

Abstract

The invention belongs to the technical field of computer aided design, and discloses a CATIA (computer aided three-dimensional interactive application)-based aircraft machining part modeling method, which comprises the following steps of: firstly, creating an external reference for the input of machine frame part modeling, then creating machining part parameters and an auxiliary surface by combining the external reference direction, and further creating feature template parameters and performing feature template calling by combining the machining part parameters and the auxiliary surface; completing the geometric construction of the machined part; and improving the attributes of the machined parts. According to the method, the machining part can be quickly modeled, and the design efficiency and stability of the machining part are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of computer-aided design and relates to a CATIA-based aviation machined parts modeling method. Background Art

[0002] With the rapid development of the aviation industry, China's investment in the manufacturing sector has continued to increase. Aircraft, particularly military aircraft, as representatives of the aviation industry, have become a key indicator of a country's scientific and technological strength, and their design and manufacturing capabilities have become a crucial indicator of national technological strength. Simultaneously, with the advancement of science and technology, companies' digital design and manufacturing capabilities are continuously improving, and computer-aided design (CAD) technology is becoming increasingly popular. Compared with traditional methods, this technology not only reduces R&D costs but also significantly improves designer efficiency.

[0003] Computer-aided design (CAD) technology has evolved from two-dimensional to three-dimensional applications, and 3D models have gained a significant presence in modern industry and design. 3D models play a key role throughout the product lifecycle, connecting design, manufacturing, process engineering, assembly, and service, serving as a bridge of communication between designers, process engineers, manufacturers, and users.

[0004] In modern aircraft design, structural component design is a highly technical and complex task. Structural components include both standard and non-standard parts. However, research on non-standard structural parts is limited, particularly aircraft machined parts. Aviation machined parts, such as connectors, stringers, and frames, play a crucial role in aircraft structural design. They are similar in appearance and structure and play a crucial role in aircraft performance, safety, and functionality. Due to the large variety and quantity of these parts, accelerating their design and manufacturing is particularly important. Relevant research shows that many companies' series products have a high degree of similarity. Overall, approximately 70%-80% of parts in mechanical product design are reused or modified from existing designs, while only approximately 20% are completely new designs. This is also true for aircraft series products. With the current proliferation of aircraft models, the development of new series requires not only short design cycles but also reliable reliability. Research has found that the design time for machined parts accounts for over 70% of the entire aircraft structural development cycle. Therefore, improving the design efficiency and reliability of aircraft machined parts, especially non-standard parts, is crucial. Summary of the Invention

[0005] The purpose of the present invention is to provide an aviation machined parts modeling method based on CATIA to address the problems of low efficiency and duplication of labor in machined parts modeling encountered in existing aircraft design, so as to achieve rapid modeling of frame parts.

[0006] In order to achieve the above objectives, the present invention adopts the following technical solutions to achieve them.

[0007] The present invention provides a CATIA-based aviation machined parts modeling method, which is characterized by comprising the following steps:

[0008] S1, creating external references for input of frame component modeling; the created external references include points, lines and / or surfaces;

[0009] S2, constructing the geometry of the machined part, which includes the following sub-steps:

[0010] S21, determine the external reference direction:

[0011] When the external reference is a line or plane, the direction of the line or / and plane is determined by the set direction parameters;

[0012] When the external reference is a surface, the direction of the surface is determined by the direction knowledge rule;

[0013] S22, creating machined part parameters; the machined part parameters include machined part size parameters;

[0014] S23, creating auxiliary surfaces: based on the direction knowledge rules, performing translation, intersection and / or splitting operations on the external reference according to the machined part parameters to obtain the auxiliary surfaces of the machined part;

[0015] S24, creating feature template parameters; the feature template parameters include auxiliary surfaces and feature parameters associated with the feature template;

[0016] S25, calling the corresponding feature template according to the feature template parameters; performing a Boolean operation on the specified entity according to the output of the feature template;

[0017] Repeat the above steps S24-S25 until the geometric structure of the frame member is achieved.

[0018] In the above step S1, an external reference is determined based on the assembly relationship of the machined part in the product. The external reference includes a point, a line, and / or a surface.

[0019] In the above step S2, constructing the geometry of the machined part is a key step, which involves key technologies such as creating directional knowledge rules, defining design parameters, and building feature templates.

[0020] In the above step S21, the purpose is to determine the external reference direction. In order to ensure the reliability and stability of the three-dimensional model of aviation machine parts, it is necessary to create corresponding knowledge engineering rules to realize knowledge reuse in the modeling process. In traditional modeling, model instability is mainly concentrated on direction selection. The problem of direction involves the selection direction of features such as lines and surfaces in CATIA. During the modeling process, it is usually necessary to manually adjust the feature direction to meet the design requirements. If it does not meet the requirements, it can only be adjusted by reversing the direction command. This operation may cause inconsistent directions when using similar structural parts or feature templates, which in turn causes errors in the model.

[0021] In this step, when the external reference is a line or plane, the direction of the line and / or plane is determined by the set direction parameters. When the external reference is a surface, the direction of the surface is determined by the established direction knowledge rules. This eliminates the need to consider direction when selecting the external reference in subsequent template calls.

[0022] The direction knowledge rule includes an area-based surface direction determination method: a surface used as an external reference is offset by a specified distance, and a direction in which the surface area decreases is used as a concave direction of the surface.

[0023] The directional knowledge rules also include a distance-based target line or target plane determination method: constructing a reference point or reference line, translating the line or plane serving as an external reference by a specified distance, and using the line or plane closest to the reference point or reference line as the target line or target plane; this is to determine a target line other than the external reference direction, such as the nail point direction.

[0024] In the above step S22, the main purpose is to create machined part parameters. The designed machined part parameters determine the external geometric shape of the part model and drive the changes in the model. The correlation is reflected in the control and influence of the parameters on the model. When the designed machined part parameters change, the related geometric features of the part model will also be adjusted accordingly. In the present invention, the machined part parameters mainly include the dimensional parameters of the machined part, and also include nail point parameters. The nail point parameters mainly involve machined parts mainly riveted in the aviation field, and the rivet position is determined by the distance parameters and number between the rivets. There are many basic dimensional parameters in the model, which mainly represent the outer shape or internal geometric shape of the part. The present invention also forms a dimension chain for the associated parameters, establishes the correlation between the parameters through dimension chain analysis, and uses the parametric modeling method of knowledge engineering to realize parameter linkage.

[0025] The purpose of steps S23-S25 is to load a feature template. To do this, you first need to obtain the feature template parameters, which include auxiliary surfaces and feature parameters. Different feature templates require different feature template parameters. The feature template can be a chamfer feature template, a sink feature template, a groove feature template, or a hole feature template. All feature templates are stored in the feature template library.

[0026] For a chamfer feature template, the output is a chamfered surface. The auxiliary surfaces include the chamfered top surface, chamfered bottom surface, chamfered end surface 1, chamfered end surface 2, left plane, and right plane, determined by the designer based on the dimensional parameters of the machined part. The feature parameters include two offset parameters, which are the distances from the intersection of the chamfered surface and the intersecting auxiliary surface to the edge line parallel to the surface to be chamfered.

[0027] For the sink feature template, the output includes a generated external curved surface, a generated sink boundary 1, and a generated sink boundary 2, which are connected as one. The generated sink boundary 1 and the generated sink boundary 2 are located on both sides of the generated external curved surface. The auxiliary surface includes the auxiliary long stringer external curved surface, the auxiliary long stringer internal curved surface, the auxiliary sink boundary 1, and the auxiliary sink boundary 2 determined by the designer based on the machined part size parameters. The feature parameters include the offset parameters of the generated external curved surface of the sink feature template relative to the auxiliary long stringer external curved surface, the offset parameters of the generated sink boundary 1 relative to the auxiliary sink boundary 1, the offset parameters of the generated sink boundary 2 relative to the auxiliary sink boundary 2, and the sink corner radius formed by the generated sink boundary 1, the generated sink boundary 2, and the generated external curved surface.

[0028] For the groove feature template, the output includes a generated transverse input surface 1, a generated transverse input surface 2, a generated longitudinal input surface 1, a generated longitudinal input surface 2 and a generated bottom input surface, which are connected as a whole. The generated transverse input surface 1, the generated transverse input surface 2, the generated longitudinal input surface 1 and the generated longitudinal input surface 2 are sequentially spliced ​​along the circumferential direction to form a side surface, the generated transverse input surface 1 is parallel to the generated transverse input surface 2, the generated longitudinal input surface 1 is parallel to the generated longitudinal input surface 2, the generated transverse input surface 1 and the generated transverse input surface 2 are perpendicular to the generated longitudinal input surface 1 and the generated longitudinal input surface 2 respectively, and the generated bottom input surface is vertically spliced ​​at the bottom of the side surface; the auxiliary surface includes the auxiliary transverse input surface 1, the auxiliary transverse input surface 2, the auxiliary longitudinal input surface 1, the auxiliary longitudinal input surface 2 and the auxiliary bottom input surface determined by the designer according to the size parameters of the machined part, the auxiliary transverse input surface 1 and the auxiliary transverse input surface 2 parallel, the auxiliary longitudinal input surface 1 is parallel to the auxiliary longitudinal input surface 2, and the auxiliary transverse input surface 1 and the auxiliary transverse input surface 2 are perpendicular to the auxiliary longitudinal input surface 1 and the auxiliary longitudinal input surface 2 respectively; the characteristic parameters include an offset parameter of the generating transverse input surface 1 relative to the auxiliary transverse input surface 1, an offset parameter of the generating transverse input surface 2 relative to the auxiliary transverse input surface 2, an offset parameter of the generating longitudinal input surface 1 relative to the auxiliary longitudinal input surface 2, an offset parameter of the generating longitudinal input surface 2 relative to the auxiliary longitudinal input surface 2, an offset parameter of the generating bottom input surface relative to the auxiliary bottom input surface, a corner radius formed between the generating transverse input surface 1 and the generating transverse input surface 2 and the generating longitudinal input surface 1 and the generating longitudinal input surface 2 respectively, and a bottom angle radius formed between the generating transverse input surface 1, the generating transverse input surface 2, the generating longitudinal input surface 1 and the generating longitudinal input surface 2 and the generating bottom input surface;

[0029] For the hole feature template, the output is a cylindrical surface; the auxiliary surface is a plane perpendicular to the hole axis, the point is the location of the hole center; the feature parameter is the hole diameter parameter.

[0030] The above-mentioned CATIA-based aviation machined parts modeling method further includes: S3, improving the properties of the frame parts, including basic information and material information.

[0031] The basic information includes the name, type and symmetric part information of the machined part. The symmetric part information here refers to whether the part is symmetrical. If so, the symmetric part information is "symmetric part", otherwise the symmetric part information is "asymmetric part".

[0032] The material information includes material number, material specification and required material rough size. The material specification here refers to the standard number of the American aviation material specification.

[0033] The CATIA-based aviation machined parts modeling method provided by the present invention has the following beneficial effects:

[0034] (1) The present invention can realize rapid modeling of machined parts and improve the design efficiency of machined parts through the designed directional knowledge rules and feature templates;

[0035] (2) The present invention can ensure the uniqueness of directional parameters and improve the reliability of machined parts design through the designed directional knowledge rules;

[0036] (3) The present invention creates parameter associations for machined part parameters, which can improve the design efficiency of machined parts while ensuring design reliability;

[0037] (4) The present invention constrains the feature template parameters through auxiliary surfaces and parameters, ensuring the uniqueness of the feature template. By calling the feature template, the efficiency of machined parts design can be further improved, the product development cycle can be shortened, and the quality and stability of machined parts can be ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic flow chart of a CATIA-based aircraft machined parts modeling method according to embodiment 1 of the present invention;

[0039] Figure 2 Create content for a schematic diagram of a surface extruded in different directions in CATIA Knowledge Engineering (a) and knowledge engineering rules for determining surface directions (b);

[0040] Figure 3 Creating content for the original plane offset diagram (a) and distance-based direction selection rules (b);

[0041] Figure 4 This is a schematic diagram of the dimension chain of frame parts;

[0042] Figure 5 This is a schematic diagram of the chamfer feature template parameters;

[0043] Figure 6 It is a list of contents contained in the feature template;

[0044] Figure 7 This is a schematic diagram of the external parameters of the frame part;

[0045] Figure 8 It is a schematic diagram of the frame part features;

[0046] Figure 9 Schematic diagram of the constructed frame part geometry. DETAILED DESCRIPTION

[0047] To make the objectives, technical solutions, and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other implementations obtained by those of ordinary skill in the art without inventive effort are within the scope of protection of the present invention.

[0048] Example 1

[0049] This embodiment provides a CATIA-based aviation machined parts modeling method. Figure 1 As shown, it includes the following steps:

[0050] S1, create external references for input of frame component modeling;

[0051] S2, constructs the geometry of machined parts;

[0052] S3, improve the properties of the rack components.

[0053] The purpose of step S1 is to create an external reference. The external reference is determined based on the assembly relationship of the machined part in the product. The external reference includes points, lines, and / or surfaces.

[0054] The above step S2 is a key step, which involves key technologies such as direction knowledge rule creation, design parameter definition, and feature template construction.

[0055] like Figure 1 As shown, step S2 includes the following sub-steps:

[0056] S21, determining an external reference direction.

[0057] In this step, when the external reference is a line or plane, the direction of the line or plane is determined by the set direction parameters. When the external reference is a surface, the direction of the surface is determined by the established direction knowledge rules.

[0058] Direction knowledge rules include a surface direction determination method based on area and a target line or target plane determination method based on distance.

[0059] Area-based surface direction determination method: The surface used as an external reference is offset by a specified distance, and the direction in which the surface area decreases is used as the concave direction of the surface.

[0060] For surfaces, the direction is determined mainly by the change in surface area. According to CATIA's internal rules, surface offset will result in area change. Figure 2As shown in (a), when the original surface is offset by 5mm and -5mm, the area of ​​the surface offset in the convex direction is significantly larger than the original surface, while the area of ​​the surface offset in the concave direction is significantly smaller than the original surface. Based on the above rules, this embodiment proposes a method for determining the surface direction based on area, and uses the internal language in the CATIA knowledge engineering module to create a knowledge engineering rule for determining the surface direction, as shown in the following example: Figure 2 As shown in (b), the part geometry is stretched according to the set stretching direction. If the surface area decreases after stretching, the concave direction of the surface is the stretching direction, otherwise the concave direction of the surface is the opposite direction of stretching to ensure the uniqueness of the surface direction.

[0061] Distance-based target line or target plane determination method: Construct a reference point or reference line, translate the line or plane used as an external reference by a specified distance, and use the line or plane closest to the reference point or reference line as the target line or target plane.

[0062] For the direction selection of lines and planes, knowledge engineering rules are mainly determined based on distance. These distances refer to the distances between the target line or target plane and the reference point or reference line, and the reference point or reference line is usually determined by external reference or machined part parameters. This embodiment uses a plane as an example to illustrate the direction selection rules based on distance. Figure 3 As shown in (a), the goal is to offset the original plane by 5mm in direction 2. When executing the offset command, the default normal direction of the original plane cannot be determined. In order to achieve the goal, it is first necessary to construct the original plane and reference point based on external references and parameters, and then create the possible target plane. Then, use the CATIA Knowledge Engineering module to create a distance-based direction selection rule, such as Figure 3 (b) shows the rule. This rule means that if the distance from the reference point to target plane 1 is greater than the distance from the reference point to target plane 2, target plane 2 is selected; otherwise, target plane 1 is selected. The line direction selection rule is similar to this method.

[0063] S22, creating machined part parameters and constructing parameter associations; the machined part parameters include machined part size parameters, and the associated parameters form a size chain.

[0064] The primary purpose of this step is to create machined part parameters. In this context, these parameters primarily include dimensional parameters and rivet point parameters. These parameters primarily relate to machined parts, primarily riveted in the aviation industry, where rivet positions are determined by the distance between rivets and their number. Basic dimensional parameters are common in models and primarily represent the part's external or internal geometry.

[0065] This embodiment also establishes the relationship between parameters through dimension chain analysis, and uses the parametric modeling method of knowledge engineering to realize parameter linkage. Figure 4 (As shown in the figure), A1 through A6 form a complete dimension chain, with the relationship A1 = A2 + A3 + A4 + A5 + A6. This relationship allows for parameter associations, achieving a parameter linkage effect. For example, if the values ​​of A1, A2, A3, A4, and A6 are known, the specific value of A5 can be determined.

[0066] An analysis of the structural characteristics of aircraft machined parts reveals four primary structural features found in current machined part models: chamfers, depressions, grooves, and holes. Based on these features, the feature templates constructed in this embodiment are chamfer, depression, groove, or hole feature templates, all of which are stored in a feature template library. The feature template-based part modeling process first determines surfaces using the feature templates. These surfaces are then used to perform Boolean operations on an initialized entity (defined by the designer, such as a cuboid) to obtain the part model.

[0067] Aircraft machined parts usually contain two or more features. In this embodiment, the modeling of such parts needs to be established through the feature templates involved in the parts. And because the structures of aircraft machined parts are mostly similar, and multi-feature parts account for a large proportion, such as long stringer connectors, frames and floors, by establishing corresponding feature templates, when establishing parts with similar structural features, especially when faced with a large number of similar structural features, modeling can be completed quickly. Studies have shown that the modeling time using structural feature templates is significantly lower than that of traditional modeling methods, thereby effectively improving modeling efficiency and shortening the product development cycle. At the same time, it avoids the failure of model size update and adjustment due to operations such as manual selection of part model edges with the mouse, thereby improving the quality of modeling and ensuring the stability of the model.

[0068] To ensure model stability and reliability, the surface defined by the feature template must be unique. To achieve this, the feature template parameters must be determined. Feature template parameters primarily refer to the parameters contained in the feature template that must be input when calling the feature template, including the auxiliary surfaces and feature parameters associated with the feature template.

[0069] like Figure 5 and Figure 6As shown, for the chamfer feature template, the output is the chamfer generation surface; the auxiliary surface includes the chamfer top surface, chamfer bottom surface, chamfer end surface 1, chamfer end surface 2, the left plane and the right plane determined by the designer; the feature parameters include two offset parameters, which are the distances from the intersection of the chamfer generation surface and the intersecting auxiliary surface to the edge line parallel to the chamfered surface to be generated. According to the size parameters of the machined part and based on the translation of the three-dimensional coordinate system, the chamfer top surface, chamfer bottom surface, chamfer end surface 1, chamfer end surface 2, the left plane and the right plane are created, and each surface is perpendicular to the adjacent surface and parallel to the opposite surface. Offset parameter 1 represents the distance from the intersection of the chamfer generation surface and the chamfer top surface intersecting with it to the edge line parallel to the chamfer generation surface (i.e. Figure 6 The chamfer length 1 corresponding to the chamfer feature in the middle), the offset parameter 2 represents the distance from the intersection line of the chamfer generating surface and the chamfer end surface 1 intersecting with it to the edge line parallel to the chamfered surface to be generated (i.e. Figure 6 The chamfer length in 2), the specific position is as follows Figure 5 shown.

[0070] like Figure 6 As shown, for the sink feature template, the output includes a generated external surface, a generated sink boundary 1, and a generated sink boundary 2, which are connected as one. The generated sink boundary 1 and the generated sink boundary 2 are located on both sides of the generated external surface; the auxiliary surface includes the auxiliary long stringer external surface determined by the designer, the auxiliary long stringer internal surface, and the auxiliary sink boundary 1 and the auxiliary sink boundary 2 determined by the designer; the auxiliary long stringer external surface is parallel to the auxiliary long stringer internal surface; the auxiliary sink boundary 1 is parallel to the auxiliary sink boundary 2, and the auxiliary sink boundary 1 and the auxiliary sink boundary 2 are perpendicular to the auxiliary long stringer external surface; the characteristic parameters include the offset parameters of the generated external surface of the sink feature template relative to the external surface of the auxiliary long stringer (i.e. Figure 6 The external surface offset corresponding to the sink feature), generates the offset parameters of the sink boundary 1 relative to the auxiliary sink boundary 1 (i.e. Figure 6 The offset parameters of the sink boundary 1 corresponding to the sink feature in the middle sink feature are generated relative to the auxiliary sink boundary 2 (i.e. Figure 6 The sink boundary 2 offset corresponding to the sink feature in the middle) and the sink corner radius formed by generating sink boundary 1, generating sink boundary 2 and generating the external surface (i.e. Figure 6 The sink corner radius corresponding to the middle sink feature).

[0071] like Figure 6As shown, for the groove feature template, the output includes a generated transverse input surface 1, a generated transverse input surface 2, a generated longitudinal input surface 1, a generated longitudinal input surface 2, and a generated bottom input surface, which are connected as a whole. The generated transverse input surface 1, the generated transverse input surface 2, the generated longitudinal input surface 1, and the generated longitudinal input surface 2 are sequentially spliced ​​along the circumferential direction to form a side surface. The generated transverse input surface 1 is parallel to the generated transverse input surface 2, the generated longitudinal input surface 1 is parallel to the generated longitudinal input surface 2, the generated transverse input surface 1 and the generated transverse input surface 2 are perpendicular to the generated longitudinal input surface 1 and the generated longitudinal input surface 2, respectively, and the generated bottom input surface is vertically spliced ​​at the bottom of the side surface; the auxiliary The auxiliary surfaces include auxiliary transverse input surface 1, auxiliary transverse input surface 2, auxiliary longitudinal input surface 1, auxiliary longitudinal input surface 2, and auxiliary bottom input surface determined by the designer. The auxiliary transverse input surface 1 is parallel to the auxiliary transverse input surface 2, the auxiliary longitudinal input surface 1 is parallel to the auxiliary longitudinal input surface 2, the auxiliary transverse input surface 1 and the auxiliary transverse input surface 2 are perpendicular to the auxiliary longitudinal input surface 1 and the auxiliary longitudinal input surface 2 respectively, and the auxiliary bottom input surface is perpendicular to the auxiliary transverse input surface 1, the auxiliary transverse input surface 2, the auxiliary longitudinal input surface 1, and the auxiliary longitudinal input surface 2. The characteristic parameters include generating an offset parameter of the transverse input surface 1 relative to the auxiliary transverse input surface 1 (i.e., Figure 6 The external surface offset corresponding to the groove feature in the middle) generates the offset parameters of the lateral input surface 2 relative to the auxiliary lateral input surface 2 (i.e. Figure 6 The internal surface offset corresponding to the groove feature) generates the offset parameters of the longitudinal input surface 1 relative to the auxiliary longitudinal input surface 2 (i.e. Figure 6 The left plane offset corresponding to the middle groove feature) generates the offset parameters of the longitudinal input surface 2 relative to the auxiliary longitudinal input surface 2 (i.e. Figure 6 The right plane offset corresponding to the groove feature in the middle) generates the offset parameters of the bottom input surface relative to the auxiliary bottom input surface (i.e. Figure 6 The bottom surface offset corresponding to the groove feature), the corner radius formed between the generated horizontal input surface 1, the generated horizontal input surface 2 and the generated vertical input surface 1 and the generated vertical input surface 2 respectively (i.e. Figure 6 The corner radius of the frame surface groove corresponding to the groove feature) and the bottom corner radius formed between the generated horizontal input surface 1, generated horizontal input surface 2, generated vertical input surface 1, generated vertical input surface 2 and generated bottom input surface (i.e. Figure 6 The bottom corner radius of the frame surface groove corresponding to the middle groove feature).

[0072] like Figure 6 As shown, for the hole feature template, the output is a cylindrical surface; the auxiliary surface is perpendicular to the hole axis, and the point is the location of the hole center; the feature parameter is the hole diameter parameter (i.e. Figure 6 (diameter of the circular lightening hole corresponding to the center hole feature).

[0073] S23, creating auxiliary surfaces: based on direction knowledge rules, the external reference is translated, intersected or / and split according to the machined part parameters to obtain the auxiliary surfaces of the machined part.

[0074] In this step, based on the previously given directional rules and the dimensional parameters of the machined part to be created, the external reference is translated, intersected, and / or split to obtain the auxiliary surface of the machined part. The obtained auxiliary surface serves as the input of the feature template.

[0075] S24, creating feature template parameters; the feature template parameters include auxiliary surfaces and feature parameters associated with the feature template.

[0076] In this step, according to the design requirements of the machined part and based on the auxiliary surface of the machined part obtained above, the feature parameters associated with the feature template are determined, and then the feature template parameters associated with the feature template are obtained.

[0077] S25, calling the corresponding feature template according to the feature template parameters; performing Boolean operations on the specified entity according to the output of the feature template.

[0078] In this step, the corresponding feature template is retrieved from the feature template library based on the feature template parameters, resulting in a feature template output. The feature template output is then used to perform Boolean operations on the specified entities (e.g., the initial entities determined by the designer) to complete the geometric construction of the corresponding features of the machined part. Boolean operations include join, combine, split, intersect, and / or cut.

[0079] Repeat the above steps S24-S25 to complete the calling of all feature templates, obtain the required machined part entity, and realize the geometric structure of the frame part.

[0080] The purpose of the above step S3 is to add attribute information to the constructed machined part, including basic information and material information.

[0081] Basic information includes the name, type, and symmetric part information of the machined part. Symmetric part information here refers to whether the part is symmetrical. If so, the symmetric part information is "Symmetric Part"; otherwise, the symmetric part information is "Asymmetric Part." For example, for a constructed connecting strip, "Name" = Connecting Strip, "Type" = Sheet Metal Part, and "Symmetric Part Information" = Symmetric Part.

[0082] The material information includes the material number, material specification and the required material rough size. The material specification here refers to the standard number of the American aviation material specification.

[0083] Application Examples

[0084] The feasibility and effectiveness of the proposed method are demonstrated using a frame in the aviation field as an example. A frame is a complex component of an aircraft's structural framework and skeleton, providing the aircraft with necessary strength, rigidity, and stability. The proposed CATIA-based aircraft machined parts modeling method is used to model the frame through steps S1-S3.

[0085] S1, create external references for input of frame component modeling.

[0086] The external reference is mainly determined by the assembly relationship of the machined parts in the entire product or component. The external reference of the frame is mainly the aircraft product shape, the frame's footprint, the long stringer's footprint, and the long stringer segmentation line. Figure 7 shown.

[0087] S21, determine the external reference direction:

[0088] In this application example, the aircraft's exterior, frame footprint, and stringer footprint are all curved surfaces. Area-based surface orientation is used to determine the concave orientation of the surfaces. For stringer segment lines, their orientation parameters are directly set.

[0089] S22, create machining part parameters.

[0090] like Figure 8 As shown, the frame part contains sunken features, groove features, and hole features. For these features, the corresponding dimensional parameters can be determined. For example, for a hole feature, the corresponding dimensional parameters of the machined part include the hole position and hole diameter.

[0091] S23, create auxiliary surface.

[0092] Based on the direction knowledge rules, the auxiliary surface of the machined part is obtained by performing translation, intersection and / or splitting operations on the external reference according to the machined part parameters.

[0093] The frame part contains different auxiliary surfaces for different features.

[0094] For the sink feature, the auxiliary surfaces include an auxiliary stringer outer surface, an auxiliary stringer inner surface, an auxiliary sink boundary 1, and an auxiliary sink boundary 2 determined by the size parameters corresponding to the sink feature of the frame part.

[0095] For the groove feature, the auxiliary surfaces include auxiliary lateral input surface 1, auxiliary lateral input surface 2, auxiliary longitudinal input surface 1, auxiliary longitudinal input surface 2 and auxiliary bottom input surface determined by the size parameters corresponding to the groove feature of the frame part.

[0096] For hole features, the auxiliary surface is a plane perpendicular to the hole axis that is determined by the size parameters corresponding to the groove feature of the frame part, and the point is the location of the hole center.

[0097] The above auxiliary surfaces and auxiliary points are based on external references and are constructed through commands such as translation, intersection, splitting and / or combining.

[0098] S24, creating feature template parameters.

[0099] Feature template parameters include auxiliary surfaces and feature parameters associated with the feature template.

[0100] As mentioned above, auxiliary surfaces for different features have been given. Combined with the corresponding dimensional parameters of each feature of the frame part, the feature parameters related to each feature template can be obtained; the auxiliary surfaces and feature parameters constitute the feature template parameters of the corresponding features.

[0101] S25, according to the feature template parameters, the corresponding feature template is called; and the loading of the feature template is completed through Boolean operation.

[0102] According to the feature template parameters of different features, use CATIA's "Instantiate from Document" command to import the feature template, select the corresponding feature template, and then perform Boolean operations on the specified entity based on the feature template output to complete the geometric construction of the corresponding features of the frame part. Repeat the above steps S24-S25 until the geometric construction of the frame part is achieved. The constructed frame part geometry is as follows Figure 9 shown.

[0103] S3, complete the properties of the frame components, including basic information and material information.

[0104] The basic information includes the name of the machined part = "frame", type "", and symmetrical part information = "asymmetric part".

[0105] The material information includes material number = "A00001", material specification = "C00001", and required material rough size = "40mm×350mm×1550mm".

[0106] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and it should be understood that the scope of protection of the present invention is not limited to such specific descriptions and embodiments. Those skilled in the art can make various other specific variations and combinations based on the technical teachings disclosed in the present invention without departing from the essence of the present invention, and such variations and combinations are still within the scope of protection of the present invention.

Claims

1. A CATIA-based aviation machined parts modeling method, characterized in that: The following steps are involved: S1, creating external references for input of frame component modeling; the created external references include points, lines and / or surfaces; S2, constructing the geometry of the machined part, which includes the following sub-steps: S21, determine the external reference direction: When the external reference is a line or plane, the direction of the line or / and plane is determined by the set direction parameters; When the external reference is a surface, the direction of the surface is determined by the direction knowledge rule; S22, creating machined part parameters; the machined part parameters include machined part size parameters; S23, creating auxiliary surfaces: based on the direction knowledge rules, performing translation, intersection and / or splitting operations on the external reference according to the machined part parameters to obtain the auxiliary surfaces of the machined part; S24, creating feature template parameters; The feature template parameters include auxiliary surfaces and feature parameters associated with the feature template; S25, calling the corresponding feature template according to the feature template parameters; performing a Boolean operation on the specified entity according to the output of the feature template; Repeat the above steps S24-S25 until the geometric structure of the frame member is achieved.

2. The CATIA-based aircraft machining part modeling method according to claim 1, characterized in that: In step S1, an external reference is determined based on the assembly relationship of the machined part in the product.

3. The CATIA-based aircraft machining part modeling method according to claim 1, characterized in that: In step S21, the direction knowledge rule includes an area-based surface direction determination method: the surface used as an external reference is offset by a specified distance, and the direction in which the surface area decreases is used as the concave direction of the surface.

4. The CATIA-based aircraft machining part modeling method according to claim 3, characterized in that: The direction knowledge rule also includes a distance-based target line or target plane determination method: constructing a reference point or reference line, translating the line or plane serving as an external reference by a specified distance, and using the line or plane closest to the reference point or reference line as the target line or target plane.

5. The CATIA-based aircraft machining part modeling method according to claim 1, characterized in that: Dimension chains are formed for parameters that are associated with each other.

6. The method for modeling aircraft machined parts based on CATIA according to claim 5, characterized in that: The machined part parameters also include nail point parameters.

7. The CATIA-based aircraft machining part modeling method according to claim 1, characterized in that: In step S25, the feature template is a chamfer feature template, a sunken feature template, a groove feature template or a hole feature template.

8. The CATIA-based aircraft machined parts modeling method according to claim 7, characterized in that: In step S25, for the chamfer feature template, the output is a chamfered generating surface; the auxiliary surface includes a chamfered top surface, a chamfered bottom surface, a chamfered end surface 1, a chamfered end surface 2, a left plane, and a right plane determined by the designer based on the dimensional parameters of the machined part; the feature parameters include two offset parameters, which are the distances from the intersection of the chamfer generating surface and the intersecting auxiliary surface to the edge line parallel to the chamfer generating surface; For the sink feature template, the output includes a generated external curved surface, a generated sink boundary 1, and a generated sink boundary 2, which are connected as one. The generated sink boundary 1 and the generated sink boundary 2 are located on both sides of the generated external curved surface. The auxiliary surface includes the auxiliary long stringer external curved surface, the auxiliary long stringer internal curved surface, the auxiliary sink boundary 1, and the auxiliary sink boundary 2 determined by the designer based on the machined part size parameters. The feature parameters include the offset parameters of the generated external curved surface of the sink feature template relative to the auxiliary long stringer external curved surface, the offset parameters of the generated sink boundary 1 relative to the auxiliary sink boundary 1, the offset parameters of the generated sink boundary 2 relative to the auxiliary sink boundary 2, and the sink corner radius formed by the generated sink boundary 1, the generated sink boundary 2, and the generated external curved surface. For the groove feature template, the output includes a generated transverse input surface 1, a generated transverse input surface 2, a generated longitudinal input surface 1, a generated longitudinal input surface 2 and a generated bottom input surface, which are connected as a whole. The generated transverse input surface 1, the generated transverse input surface 2, the generated longitudinal input surface 1 and the generated longitudinal input surface 2 are sequentially spliced ​​along the circumferential direction to form a side surface, the generated transverse input surface 1 is parallel to the generated transverse input surface 2, the generated longitudinal input surface 1 is parallel to the generated longitudinal input surface 2, the generated transverse input surface 1 and the generated transverse input surface 2 are perpendicular to the generated longitudinal input surface 1 and the generated longitudinal input surface 2 respectively, and the generated bottom input surface is vertically spliced ​​at the bottom of the side surface; the auxiliary surface includes the auxiliary transverse input surface 1, the auxiliary transverse input surface 2, the auxiliary longitudinal input surface 1, the auxiliary longitudinal input surface 2 and the auxiliary bottom input surface determined by the designer according to the size parameters of the machined part, the auxiliary transverse input surface 1 and the auxiliary transverse input surface 2 parallel, the auxiliary longitudinal input surface 1 is parallel to the auxiliary longitudinal input surface 2, and the auxiliary transverse input surface 1 and the auxiliary transverse input surface 2 are perpendicular to the auxiliary longitudinal input surface 1 and the auxiliary longitudinal input surface 2 respectively; the characteristic parameters include an offset parameter of the generating transverse input surface 1 relative to the auxiliary transverse input surface 1, an offset parameter of the generating transverse input surface 2 relative to the auxiliary transverse input surface 2, an offset parameter of the generating longitudinal input surface 1 relative to the auxiliary longitudinal input surface 2, an offset parameter of the generating longitudinal input surface 2 relative to the auxiliary longitudinal input surface 2, an offset parameter of the generating bottom input surface relative to the auxiliary bottom input surface, a corner radius formed between the generating transverse input surface 1 and the generating transverse input surface 2 and the generating longitudinal input surface 1 and the generating longitudinal input surface 2 respectively, and a bottom angle radius formed between the generating transverse input surface 1, the generating transverse input surface 2, the generating longitudinal input surface 1 and the generating longitudinal input surface 2 and the generating bottom input surface; For the hole feature template, the output is a cylindrical surface; the auxiliary surface is a plane perpendicular to the hole axis, the point is the location of the hole center; the feature parameter is the hole diameter parameter.

9. The CATIA-based aircraft machined parts modeling method according to any one of claims 1 to 8, characterized in that: Also includes: S3, complete the properties of the frame components, including basic information and material information.

10. The CATIA-based aircraft machined parts modeling method according to claim 9, characterized in that: In step S3, the basic information includes the name, type and symmetrical part information of the machined part; the material information includes the material number, material specification and required material rough size.

Images