Parametric sketch-driven metal tube furniture structure deconstruction and re-assembly design method

Abstract

This invention discloses a parametric sketch-driven method for the deconstruction and reassembly assembly design of metal tubular furniture, belonging to the field of digital furniture design and intelligent manufacturing technology. The method includes: decoupling the furniture structure into multiple sheet-like substructures and establishing a parametric template library; extracting primitive data and determining connection types by identifying the geometric and topological features of user-defined 2D sketches; automatically matching and driving the templates to generate 3D substructures, completing the process design of connection details; calculating assembly positioning benchmarks and contact areas based on the spatial relationships between sketches, generating connection features to achieve automatic assembly; and finally, performing dimensional verification and closed-loop updates on the assembly. The entire process requires no manual intervention and can output a production-ready digital model and processing data within minutes, significantly improving the efficiency, accuracy, and manufacturability of customized metal tubular furniture design.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary field of digital design and intelligent manufacturing, specifically involving a parametric sketch-driven structural deconstruction and reassembly method for metal tubular furniture, which can be widely applied to the rapid development and flexible production of small-batch, customized metal furniture products. Background Technology

[0002] With the increasing scarcity of global timber resources and increasingly stringent environmental policies in various countries, metal tubular furniture has rapidly emerged in the residential and commercial furniture markets due to its advantages such as high strength, flame retardancy, moisture resistance, and full recyclability. However, the current design and production models for metal tubular furniture still face significant bottlenecks, specifically manifested in the following technical issues: 1. Rigid and insufficiently standardized design patterns make it difficult to adapt to diverse customization needs: Existing design systems lack effective modular and standardized design methods, resulting in low reuse rates of design resources and slow response times. Traditional design processes rely on fixed template libraries or entirely manual modeling, failing to achieve rapid combination and adjustment of design elements. Especially in small-batch, multi-variety customization scenarios, the design iteration cycle is long, making it difficult to meet the market's demand for rapidly changing shapes and dimensions. 2. High design threshold makes it difficult for non-professional users to participate in the customization process: Current 3D modeling design tools are complex to operate, requiring professional engineering knowledge, limiting the direct participation of designers, sales consultants, and end-users. The lack of intuitive, low-threshold design input methods makes it difficult to accurately and efficiently convert user design intentions into executable engineering data, hindering the popularization of personalized customization services and user experience. 3. Low degree of automation in the design-to-manufacturing process, relying on manual intervention: Throughout the entire process from sketch to manufacturable model, geometric continuity analysis, pipe specification matching, connection node design, assembly relationship calculation, and processing feature generation still require a significant amount of manual operation. Traditional processes take hours or even days to complete, resulting in low efficiency and the potential for errors due to manual operation, making it difficult to ensure consistency between design and manufacturing data. 4. Lack of intelligent optimization in connection design leads to insufficient manufacturability and assembly precision: Existing methods lack process compensation mechanisms in connection node design, such as welding bevel reservation, tube fitting clearance control, and hole position deviation compensation. This leads to a disconnect between the design model and actual manufacturing conditions, easily causing assembly interference, springback deviation, and other problems, requiring repeated trial production and correction, increasing material waste and production costs. 5. Lack of effective dimensional verification and closed-loop optimization mechanisms: In traditional design processes, assembly dimensional verification relies on manual measurement and comparison, which is inefficient and prone to errors. After problems are discovered, the modification process is cumbersome, lacking a parameterized correlation-driven automatic update and reassembly mechanism, making it difficult to achieve rapid iterative optimization and affecting design quality and first-time success rate. 6. Disconnect between design and manufacturing systems makes it difficult to support flexible production modes: There is a gap between the data format output by existing design methods and the processing data required by automated production lines, making it impossible to achieve design-manufacturing integration. In scenarios involving small-batch, diversified orders, it is difficult to quickly generate machining instructions that can directly drive CNC equipment, hindering the deployment of flexible production lines and the improvement of production efficiency.

[0003] In summary, there is an urgent need in this field for an innovative design methodology that can reduce design complexity through modular deconstruction, lower the barrier to entry through sketch-driven approaches, achieve full-process automation to improve efficiency, integrate intelligent process optimization to ensure manufacturability, establish closed-loop dimensional verification to ensure quality, and ultimately output data that can be directly used for flexible manufacturing, thereby systematically solving multiple technical bottlenecks in the customized design of metal tube furniture. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a rapid design method for metal tubular furniture. This method involves designing a parameterized basic tubular material database, dividing the furniture into combinations of multiple sheet-like substructures, identifying and drawing sketches of these sheet-like substructures, assigning the identified sketch information to the database, creating the sheet-like substructures through the assembly and connection of the basic tubular materials, and finally realizing the assembly and connection methods between the sheet-like substructures based on the relationships between the line segments in the drawn sketches, thereby improving design efficiency.

[0005] A rapid design method for metal furniture includes the following steps: S1. Deconstruct the furniture structure and build a parametric database; S2. Draw and recognize custom sketches; S3, Instantiate the sheet substructure; S4. Determine the assembly relationships and generate the assembly; S5. Calibrate dimensions and update the model.

[0006] Furthermore, step S1 specifically includes: S1.1 Analyze the structure of the target furniture: Perform structural analysis on the target metal tubular furniture.

[0007] S1.2, Decomposition into sheet-like substructures: Based on the principles of functional independence, manufacturing feasibility, standardization and serialization, and packaging flattening, the overall structure is decomposed into multiple sheet-like substructures M. i .

[0008] Assume that the metal tubular furniture F consists of n sheet-like substructures M i The composition is F = { M1, M2, ..., M} n}, M i Its own data structure is shown in the table below: ; S1.3 Establish a parametric basic pipe template library: Establish a parametric basic pipe database corresponding to the sheet-like substructure, including templates such as straight pipes, L-shaped bends, rounded rectangles, and right-angled rectangles. Each template is associated with adjustable parameters (length, bending radius, cross-sectional dimensions, and wall thickness).

[0009] S2. Draw and recognize custom sketches S2.1 Drawing a 2D sketch: The user draws each sheet-like substructure M on a 2D plane. i The sketch consists of geometric elements such as straight lines and arcs, representing the geometric center line of the pipe, ensuring that the geometric center of the sketch is (0,0).

[0010] S2.2 Filtering Redundant Elements and Analyzing Continuity: Traverse the sketch line segments and filter redundant elements such as auxiliary lines; perform continuity analysis based on the endpoint information of the line segments. Assume that the endpoint of one line segment is (x1, y1) and the starting point of another line segment is (x2, y2). If the two points satisfy formula (1), that is, the endpoints coincide, then it is G. 0 Continuous line segments; if satisfying G 0 Under the premise that the endpoints intersect and the tangent vectors are in the same direction, then it is G. 1 Continuous line segments. Multiple continuous line segments are merged and identified as a single geometric element, with each element corresponding to a basic pipe.

[0011] (1) (2) In the formula: ε is the tolerance threshold, which is less than 0.01mm, and t1 and t2 are the tangent vectors of (x1,y1) and (x2,y2), respectively.

[0012] S2.3 Extracting Geometric Attributes and Assigning Pipe Specifications: Extract the ID of each primitive and calculate its geometric attributes such as length and corner radius using the endpoint coordinates. i Assign pipe specification information P to the primitive according to preset or user-specified settings. i It includes the outer diameter, wall thickness and cross-sectional shape.

[0013] S2.4 Identify topological relationships and connection types: Identify connection points V based on the coincidence of primitives; define the primitives sharing connection points V as connection primitive pairs R, and calculate the included angle using formula (3) based on the vector of the primitive at connection point V; determine the connection type A (welding or pipe connection): if the pipe specifications of the connection primitive pairs are the same, it is welding; if the specifications are different and they are T-shaped connections, it is pipe connection.

[0014] (3) S2.5, Generate structured primitive data: Combine the identified primitive IDs and geometric attributes G... i Pipe specifications information P i and topology information T i (Including connection point V, connection primitive pair R, and connection type A), generate a structured primitive data structure, as shown in the table below: ; Furthermore, step S3 specifically includes: S3.1 Matching basic templates: Based on the primitive data structure generated in step S2, match the basic templates in the template library according to the primitive type (e.g., a straight primitive matches a linear template; a rounded rectangle composite primitive matches a rounded rectangle template).

[0015] S3.2 Driving Template Parameters: Call the parameterized driving function to pass the geometric properties (length, bending radius, etc.) of the primitive to the matching template. The driving template automatically adjusts its size to ensure that the geometric center line of the pipe completely coincides with the sketch primitive.

[0016] S3.3, Design Connection Details: Design the details according to the connection type A of the primitive: For primitive pairs of pipes with a welding connection type, the shortening function is called to shorten the pipe at connection point V by an appropriate length, simulating the allowance for the weld bevel. For primitive pairs of pipes with a plug connection type: for small-sized "plug pipes," the lengthening function is used in the connection segment to increase the length of the pipe model by an appropriate length. For large-sized "socket pipes," a positioning hole is generated at connection point V, with the hole diameter increased by 0.2-0.4 mm and the hole depth half the specification of the socket pipe.

[0017] Furthermore, step S4 specifically includes: S4.1 Calculate the plane normal vector Calculate the normal vector of the plane containing each substructure sketch, for example, three contacting sheet-like substructures M. i M j and M k M i The normal vector is along the Z-axis, M j The normal vector is along the X-axis, M k If the normal vector is along the Z-axis, then M i With M j mutually perpendicular, M i With M k parallel to each other.

[0018] S4.2 Extract sketch intersections Extract the intersection points of different substructure sketch primitives (such as M). i With M j The intersection points J1 and J2 of the sketch are used as precise positioning references for cannulation connection.

[0019] S4.3 Identifying Parallel Primitive Pairs Identifying different sheet-like substructures M iParallel primitive pairs between sketch primitives are identified, and their perpendicular distance is calculated. If this distance is less than the tolerance threshold set based on the pipe specification, it is the shortest perpendicular distance parallel primitive pair Pr. The pipe surface represented by this pair of primitives is determined to be the contact surface, and this contact surface is used as the reference area for the bolt connection.

[0020] S4.4, Generate Connection Features At the identified positioning reference point, blind holes for tube connection and fixed bolt through holes are generated on the corresponding pipe. Within the identified reference area, avoiding the connection point V of the sheet-like substructure sketch primitives, bolt connection hole features are uniformly generated based on the center of the reference area.

[0021] Furthermore, step S5 specifically includes: S5.1, Check Assembly Dimensions: After furniture assembly is completed, check the overall dimensions of the assembly, such as total length, total width, and total height. If they do not match the preset furniture dimensions, locate the sheet-like substructures that caused the dimensional deviation.

[0022] S5.2 Modify Sketch and Rebuild Model: Modify the sketch dimensions of the responsible sheet substructure. After modification, the changes in sketch information are transmitted to the corresponding base pipe model through parametric association, driving its update again. The updated sheet substructure is automatically reassembled and its dimensions are recalibrated until the design requirements are met.

[0023] Compared with the prior art, this application has the following beneficial effects: 1. It enables modular and standardized rapid design of metal tubular furniture, significantly improving design reusability and response efficiency. By systematically deconstructing the overall structure of metal tubular furniture, it is broken down into multiple independently designable and manufactureable sheet-like sub-structural units, and a parametric template library containing various basic tubular material forms is established. This approach transforms the design process from traditional overall modeling to modular combination, allowing designers to quickly call, replace, and adjust different substructures, greatly improving the reusability of design resources. Simultaneously, based on the parametric-driven mechanism, modifications to design dimensions and forms can be transmitted to all related structural units in real time, achieving "one change, all changes," significantly shortening the design iteration cycle. This is particularly suitable for small-batch, multi-variety customized production scenarios, enabling rapid response to changes in market demand.

[0024] 2. Significantly lowers the design threshold, supporting non-professional users to participate in the customized design process. Users can drive the entire design process simply by drawing a 2D sketch that expresses their design intent. The system intelligently identifies the geometric and topological features of the sketch, automatically extracts geometric primitives, determines connection types, and converts them into structured engineering data, without requiring users to have professional 3D modeling knowledge. This "sketch-driven" design approach greatly lowers the technical threshold, allowing designers, sales consultants, and even end users to intuitively participate in the creation of furniture forms, truly realizing "design freedom" and broadening the user base for personalized customization.

[0025] 3. Achieve full automation from sketch to manufacturable model, greatly improving design and production efficiency. This invention automates the entire process from sketch analysis, parametric modeling, structural assembly to manufacturing feature generation. The system automatically completes geometric continuity analysis, pipe specification matching, detailed design of connection nodes, assembly relationship calculation, and connection feature generation, all without manual intervention. The 3D modeling, assembly, and drawing processes that traditionally take hours or even days can be completed automatically in minutes, improving design efficiency by over 80%. Simultaneously, the output is a digital model and processing data that can be directly used in automated processing equipment such as CNC pipe bending and laser cutting, achieving integrated design and manufacturing.

[0026] 4. Improve structural rationality and manufacturing feasibility through intelligent connection design and process compensation. The system automatically determines the connection type (welding / insertion) based on pipe specifications and connection angles, and performs detailed manufacturing-guided design: weld joints automatically allow for beveling allowances, and insert joints automatically generate positioning holes with clearance compensation (e.g., hole diameter enlargement of 0.2–0.4 mm). Furthermore, it automatically identifies assembly datums based on sketch intersections and parallel relationships, generates bolt connection holes, and automatically avoids existing connection points. These intelligent design mechanisms effectively avoid process problems such as assembly interference and springback deviations, improving design manufacturability and assembly accuracy, and reducing the number of trial productions and material waste.

[0027] 5. Supports automatic verification and closed-loop optimization of design dimensions to ensure consistent design quality. After the assembly is generated, the system automatically detects key dimensions such as total length, total width, and total height, and compares them with user-preset values ​​to quickly locate the responsible substructure for dimensional deviations. Users can modify the corresponding sketch dimensions to drive the model to automatically update and reassemble, forming a closed-loop process of "design-verification-correction." This mechanism ensures that the final output model strictly meets design requirements, improves the first-time design success rate, and reduces rework costs caused by dimensional errors.

[0028] 6. Promote the transformation of the metal furniture industry towards digital and flexible production models. This invention deeply integrates parametric design, topology recognition, and automated assembly technologies to construct a complete digital link from user intent to processing data. It is not only suitable for single-item customization but can also seamlessly integrate with flexible production lines, supporting mixed-flow production of multiple orders. By improving design speed, accuracy, and automation levels, this method provides a systematic technical solution for the metal tubular furniture industry to address the trend of small-batch, diversified markets, demonstrating significant technological advancement and industrial application value. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the metal tubular furniture design method of the present invention; Figure 2 Custom sketch of the upper sheet-like substructure; Figure 3 Geometric primitive diagram; Figure 4 Topological relationship diagram between primitives; Figure 5 Three-dimensional model diagram of the sheet-like substructure; Figure 6 3D model diagram showing detailed design of the sheet-like substructure; Figure 7 Diagram of assembly reference points and reference areas between sheet-like substructures; Figure 8 Assembly diagram; Figure 9 A schematic diagram of the modified and reconstructed model sketch. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0031] Design a single metal tube sofa with a total length of 860mm, a total width of 720mm, a total height of 700mm, and a base 200mm off the ground.

[0032] A design method for metal tubular furniture, such as Figure 1 As shown, it includes the following steps: S1. Deconstruct the furniture structure and build a parametric database. S1.1 Analyze the structure of the target furniture: Perform structural analysis on the single metal tube sofa.

[0033] S1.2, Decompose into sheet-like substructures: Based on the four principles, deconstruct it into four sheet-like substructures M. i Its data structure is defined as shown in the table below: ; The specific definitions are as follows: ; S1.3 Establish a parametric basic pipe template library: Establish a parametric database containing templates for straight pipes, L-shaped bends, rounded rectangles, right-angled rectangles, etc.

[0034] S2. Draw and recognize custom sketches S2.1 Draw a two-dimensional sketch Draw sketches for each sheet-like substructure. The sketch for the left sheet-like substructure M2 is 860×600mm and consists of 10 line segments (4 arcs and 6 straight lines); the sketch for the upper sheet-like substructure M1 is 708×850mm and consists of 10 straight line segments; the sketch for the rear sheet-like substructure M4 is 600×500mm and consists of 6 straight line segments, as shown below. Figure 2 As shown.

[0035] S2.2 Filter redundant elements and analyze continuity Traverse the sketch and perform continuity analysis based on endpoint coordinates and tangent vectors. In M1, the endpoint coordinates of 10 line segments do not satisfy formula (1), meaning there are no continuous line segments; in M2, line segments 1-8 satisfy formulas (1) and (2), which is G. 1 A continuous line segment of a rounded rectangle forms a basic element; in M4, line segment 1-4 satisfies formula (1) but not formula (2), which is G. 0 A continuous line segment of a right-angled rectangle constitutes a basic unit. The basic unit sketch of each sheet-like substructure is shown below. Figure 3 As shown.

[0036] S2.3 Extracting Geometric Attributes and Assigning Pipe Specifications: Extract the ID, length, and shape of each primitive and assign the corresponding pipe specifications, as shown in the example below: ; (Note: M3 is a mirror image of M2, and the template matching is the same as M2.) S2.4 Identifying Topological Relationships and Connection Types Identify the connection points V and R of each sketch primitive, and calculate the included angle of the primitives at the connection points using formula (3). For example, in M1, primitives e1 and e2 intersect at point V2 with an included angle of 90°, and the pipe specifications are the same, so it is determined to be a welded connection; primitives e2 and e5 intersect at point V3 with an included angle of 90°, the pipe specifications are different and they are connected in a T-shape, so it is determined to be an insertion connection.

[0037] S2.5. Generate structured primitive data: Transmit the identified primitive information to the database in the form of a data structure. For example, the data structure of primitive e2 in M2 is shown in the table below: ; S3, Instantiate sheet structure S3.1 Matching the basic template Based on the primitive shapes identified in step S2, the corresponding basic pipe templates are matched. The specific matching is shown in the table below: ; (Note: M3 is a mirror image of M2, and the template matching is the same as M2.) S3.2, Driver Template Parameters The cell length and pipe specification information are passed to the base template to drive its reconstruction: M1: The length of the e1 and e2 drive linear modules is 700mm (50×50×2.0mm); the length of the e2 and e4 drive modules is 800mm (50×50×2.0mm); e5-e 10 The drive length is 550mm (40×40×1.0mm).

[0038] M2: The rounded rectangular module driven by e1 is 860×600mm with a rounded corner radius of 60mm (60×60×1.5mm); the length of the linear modules driven by e2 and e4 is 540mm (40×40×1.0mm).

[0039] M4: The e1 drive right-angled rectangular module is 600×500mm (50×50×1.5mm); the e2 and e3 drive linear modules are 540mm long (40×40×1.0mm).

[0040] Place the base pipes so that their geometric centerline coincides with the sketch primitives to generate a 3D model, such as... Figure 5 .

[0041] S3.3, Design Connection Details: Design the details according to connection type A between the sketch primitives. The table below lists the connection types at the intersections of each substructure primitive: ; The design should be based on the connection type: the corresponding pipe material should be appropriately shortened at the welding point; for the insertion connection, the hole feature should be designed on the "socket" pipe based on the connection point, and the "plug" pipe material should be appropriately extended, such as... Figure 6 .

[0042] S4. Determine assembly relationships and generate the assembly. S4.1 Calculate the plane normal vector: Obtain the normal vector of the plane where the four sheet-like substructure sketches are located. M2 is in perpendicular contact with M1 and M4, and M1 and M4 are parallel.

[0043] S4.2 Extract sketch intersections: Obtain the intersections of the four sheet-like substructure sketches as assembly positioning reference points, as shown in the table below: ; The intersection location and the corresponding pipe contact area are as follows: Figure 7 As shown.

[0044] S4.3 Identify parallel primitive pairs: Obtain the shortest perpendicular distance of the parallel primitive pairs Pri in the four sheet-like substructure sketches as the reference area for bolt connections, as shown in the table below: ; The identified reference area is as follows Figure 7 As shown in C1, C2, and C3.

[0045] S4.4, Generate Connection Features Blind holes with a diameter of 50.2×50.2mm (0.2mm larger than the plug tubing) are designed at intersections J1, J2, J3, and J4, and Φ18mm through holes are designed for bolt fixing.

[0046] Design Φ18mm through-hole features in the reference areas C1, C2, and C3, avoiding the connection points Vi between the sketch primitives, with a hole spacing of 100mm.

[0047] The effect after assembly is as follows Figure 8 As shown.

[0048] S5. Calibrate dimensions and update model. S5.1 Detect assembly dimensions: After assembly, the total width of the assembly is measured to be 718mm, which is less than the preset width of 720mm. The positioning responsibility piece substructure is M1.

[0049] S5.2 Modify the sketch and rebuild the model: Extend the width of the M1 sketch by 2mm, drive the model to rebuild and reassemble, and measure the dimensions again to ensure they meet the preset requirements (e.g., Figure 9 ).

[0050] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. All components not explicitly stated in this embodiment can be implemented using existing technology.

Claims

1. A parametric sketch-driven method for the structural deconstruction and reassembly assembly design of metal tubular furniture, characterized in that, Includes the following steps: S1. Structural Deconstruction and Template Library Construction: Decompose the target metal tubular furniture structure into multiple sheet-like substructures M i And establish a parametric template library containing various basic pipe shapes; S2, Sketch-driven and primitive recognition: For each sheet-like substructure M i Draw a 2D sketch, automatically identify the continuity between sketch line segments, merge continuous line segments into geometric primitives; extract the geometric properties G of each primitive. i With pipe specification P i It also identifies the connection points V, connection types A, and topological relationships between primitives, and generates structured primitive data. S3. Parametric Instantiation and Detailed Design: Match and drive the corresponding template according to the basic data to generate a three-dimensional pipe model; Perform automated process design on the connection node based on the connection type A, including shortening the bevel length of the welded connection and compensating for the fitting gap and generating positioning holes for the insertion connection. S4. Automatic Assembly and Feature Generation: Based on the spatial relationship between the sketches of each sheet-like substructure, automatically calculate the assembly positioning reference and contact area, and generate the corresponding connection hole features. S5. Dimension Verification and Closed-Loop Update: The generated assembly is dimensionally checked and compared with preset values. If deviations are found, the responsible substructure is located and its sketch is modified, driving the model to automatically update and reassemble until the design requirements are met.

2. The method according to claim 1, characterized in that, In step S1, the basis for the splitting includes functional independence, manufacturing process feasibility, standardization and serialization, and the principle of packaging flattening.

3. The method according to claim 1, characterized in that, In step S2, the identification of continuity includes: determining G based on the coincidence of the coordinates of the line segment endpoints. 0 Based on the continuity and the coincidence of the endpoints of the line segments, G is determined according to the consistency of the tangent vector directions at the endpoints. 1 Continuous; will satisfy G 1 Continuous line segments are merged into a composite geometric element.

4. The method according to claim 1, characterized in that, In step S2, the rule for determining connection type A is as follows: if the pipe specifications of the connection element pair are the same, it is determined to be a welded connection; if the pipe specifications are different and the included angle at the connection point is T-shaped, it is determined to be an insertion connection.

5. The method according to claim 1, characterized in that, In step S3, the gap compensation specifically involves setting the diameter of the positioning hole for the insertion tube connection to be 0.2-0.4 mm larger than the outer diameter of the plug tube.

6. The method according to claim 1, characterized in that, In step S4, the automatic calculation of assembly positioning reference and contact area includes: calculating the sketch plane normal vector to identify the parallel or perpendicular relationship between substructures; extracting the intersection points between sketch primitives of different substructures as positioning reference points; and identifying parallel primitive pairs Pr between different substructures with a distance less than the tolerance threshold as contact areas.

7. The method according to claim 6, characterized in that, In step S4, the features for generating connection holes include: generating blind holes and bolt fixing through holes on the pipe corresponding to the positioning reference point; and uniformly generating bolt connection holes on the surface of the pipe corresponding to the contact area, avoiding the original connection point V.

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