Thread assembly connection process parameter optimization method and monitoring device based on precise digital twinning

Abstract

The invention discloses a thread assembly connection process parameter optimization method based on precise digital twinning and a monitoring device, and relates to the field of intelligent manufacturing. The method comprises the following steps: constructing a geometric distribution error model of the thread assembly contact surface based on point cloud data of the thread assembly contact surface; integrating the geometric distribution error model of the thread assembly contact surface with the three-dimensional model of the assembled part to obtain a solid model with a three-dimensional geometric error; constructing a bolt three-dimensional model with a three-dimensional geometric distribution error based on the bolt point cloud data; performing virtual assembly on the two solid models and the bolt three-dimensional model to obtain an accurate geometric digital twin model of the thread assembly connection structure; substituting the physical condition data into the precise geometric digital twinborn model to obtain a precise physical digital twinborn model; the precision and the performance of a physical system after thread fastening are taken as optimization targets, and technological parameters of thread assembly connection are optimized. According to the invention, the accuracy of threaded assembly connection process parameters can be improved, and high-precision and high-performance products can be obtained.

Description

Technical Field

[0001] This application relates to the field of intelligent manufacturing, and in particular to a method and monitoring device for optimizing process parameters of threaded assembly connections based on precise digital twins. Background Technology

[0002] Threaded connections are one of the most widely used connection methods in the assembly of electromechanical products. Optimizing and controlling threaded assembly connection process parameters, such as thread tightening force and tightening sequence, are key technological processes to ensure product accuracy and performance. Electromechanical product accuracy refers to the geometric position and dimensional accuracy of key components in static or dynamic states after assembly. Electromechanical product performance refers to the product's motion characteristics, mechanical properties, and other characteristics that fulfill the product's design functional requirements. For precision electromechanical products, the stability of accuracy and performance refers to the characteristics of accuracy and performance variation (especially deterioration) with changes in time, temperature, and environment. For electromechanical products assembled with threaded connections, accuracy, performance, and the stability of accuracy and performance are the main indicators for measuring their quality level both domestically and internationally, and the threaded connection process is the main factor affecting these indicators. It is generally believed in the industry that 60%-70% of product accuracy and performance is determined by the level of assembly process technology.

[0003] For threaded assembly connection processes, the thread tightening process for most instruments is determined by experienced workers based on their experience and intuition, resulting in products with questionable accuracy and performance. Alternatively, some manufacturers use idealized 3D design models and finite element analysis to calculate threaded assembly connection process parameters (such as thread tightening force). However, relying on these calculated parameters to guide the threaded assembly connection process often leads to significant discrepancies between the actual accuracy and performance of the resulting products and the design goals. Therefore, optimizing threaded assembly connection process parameters to obtain high-precision, high-performance products is a pressing issue that needs to be addressed. Summary of the Invention

[0004] The purpose of this application is to provide a method and monitoring device for optimizing threaded assembly connection process parameters based on precise digital twins, which can improve the accuracy of threaded assembly connection process parameters, thereby obtaining high-precision and high-performance products.

[0005] To achieve the above objectives, this application provides the following solution: Firstly, this application provides a method for optimizing process parameters of threaded assembly connections based on precise digital twins, including: Acquire point cloud data of the threaded assembly contact surface and bolt point cloud data; A geometric distribution error model of the thread assembly contact surface is constructed based on the point cloud data of the thread assembly contact surface. The geometric distribution error model is integrated with the three-dimensional model of the assembled part to obtain a three-dimensional solid model with three-dimensional geometric errors. A 3D model of the bolt with 3D geometric distribution error is constructed based on the bolt point cloud data; The two three-dimensional solid models and the three-dimensional bolt model are virtually assembled to obtain an accurate geometric digital twin model of the threaded assembly connection structure after virtual assembly. By inputting the physical condition data into the precise geometric digital twin model, a precise physical digital twin model of the threaded assembly connection structure is obtained; the physical condition data includes: static and dynamic environmental data, material data, and nonlinear characteristic data; Using the precise physical digital twin model, with the accuracy and performance of the physical system after thread fastening as the optimization target, the thread assembly connection process parameters are optimized to obtain the optimal thread assembly connection process parameters. Among them, the spatial position and orientation of the assembled parts in the physical system after thread tightening characterize the accuracy of the physical system, and the maximum stress and stress distribution uniformity inside the physical system after thread tightening characterize the performance of the physical system; the threaded assembly connection process parameters include: thread tightening force and tightening sequence.

[0006] In one embodiment, a geometric distribution error model of the threaded assembly contact surface is constructed based on the point cloud data of the threaded assembly contact surface, specifically including: Based on the point cloud data of the threaded assembly contact surface, a geometric distribution error model of the threaded assembly contact surface is constructed using the most curved surface fitting method.

[0007] In one embodiment, the two three-dimensional solid models and the bolt three-dimensional model are virtually assembled to obtain a precise geometric digital twin model of the virtually assembled threaded assembly connection structure, specifically including: A three-point solution algorithm that makes the assembly force within a triangle is used to virtually assemble the two three-dimensional solid models to obtain the virtual assembled three-dimensional solid model; the triangle is formed by three contact points determined based on the minimum contact distance between the contact surfaces of the two three-dimensional solid models; The three-dimensional solid model after virtual assembly is virtually assembled with the three-dimensional model of the bolt to obtain an accurate geometric digital twin model of the threaded assembly connection structure after virtual assembly.

[0008] In one embodiment, the precise physical digital twin model is used to optimize the threaded assembly connection process parameters, with the accuracy and performance of the physical system after thread fastening as the optimization objective, to obtain the optimal threaded assembly connection process parameters, specifically including: Using the precise physical digital twin model, the spatial position and orientation of the assembly determined by the user according to the design and process are used as the accuracy constraint target, 60%-70% of the material yield limit is used as the maximum stress constraint target, and the uniformity requirement of stress distribution is used as the stress distribution uniformity constraint target. The threaded assembly connection process parameters are optimized to obtain the optimal threaded assembly connection process parameters.

[0009] In one embodiment, the static and dynamic environmental data includes: temperature, load, and assembly force; the material data includes: data on various material parameters in the threaded assembly connection structure; the material parameters include: elastic modulus, Poisson's ratio, and coefficient of linear expansion; the nonlinear characteristic data includes: stress relaxation data, structural creep data, and friction data within the physical system.

[0010] In one embodiment, after obtaining the optimal threaded assembly connection process parameters, the threaded assembly connection process parameter optimization method based on precise digital twins further includes: Based on the thread tightening force in the optimal thread assembly connection process parameters, determine the number of threads and the thread diameter for thread assembly tightening feed.

[0011] Secondly, this application provides a real-time monitoring device for the position and sequence of a threaded assembly process, comprising: a computer system for integrating and processing data of the threaded assembly process and a real-time monitoring device for the position and sequence of an intelligent tightening process; the computer system for integrating and processing data of the threaded assembly process and the real-time monitoring device for the position and sequence of an intelligent tightening process have a real-time data transmission function. The computer system for integrating and processing data during the thread assembly process includes: The data acquisition module is used to acquire point cloud data of the threaded assembly contact surface and bolt point cloud data; The geometric distribution error model construction module for the threaded assembly contact surface is used to construct a geometric distribution error model for the threaded assembly contact surface based on the point cloud data of the threaded assembly contact surface. A 3D model integration module is used to integrate the geometric distribution error model with the 3D model of the assembled parts to obtain a 3D solid model with 3D geometric errors. A bolt 3D model construction module is used to construct a bolt 3D model with 3D geometric distribution error based on the bolt point cloud data; The virtual assembly module is used to virtually assemble the two three-dimensional solid models and the three-dimensional bolt model to obtain a precise geometric digital twin model of the threaded assembly connection structure after virtual assembly. The precise physical digital twin model construction module is used to input physical condition data into the precise geometric digital twin model to obtain a precise physical digital twin model of the threaded assembly connection structure; the physical condition data includes: static and dynamic environmental data, material data, and nonlinear characteristic data; The parameter optimization module is used to optimize the threaded assembly connection process parameters by using the precise physical digital twin model, with the accuracy and performance of the physical system after thread fastening as the optimization target, so as to obtain the optimal threaded assembly connection process parameters. Among them, the spatial position and orientation of the assembled parts in the physical system after thread tightening characterize the accuracy of the physical system, and the maximum stress and stress distribution uniformity inside the physical system after thread tightening characterize the performance of the physical system; the threaded assembly connection process parameters include: thread tightening force and tightening sequence. The data transmission module is used to send the optimal threaded assembly connection process parameters to the intelligent tightening process position and sequence real-time monitoring device, and at the same time receive feedback data on the execution results of the intelligent tightening process position and sequence in real time. The intelligent tightening process position and sequence real-time monitoring device is used to assemble the physical object according to the optimal thread assembly connection process parameters.

[0012] In one embodiment, the intelligent tightening process position and sequence real-time monitoring device includes: an intelligent tightening tool, a tightening position indicating laser emitting device, a tool position indicating laser emitting device, and a monitoring system; the thread assembly process data integration and processing computer system further includes: a control module; the monitoring system and the intelligent tightening tool are both connected to the control module; The tightening position indicating laser emitting device is used to emit a first indicating laser to indicate the threaded hole on the assembled part; the tool position indicating laser emitting device is used to emit a second indicating laser to indicate the position of the intelligent tightening tool; the intelligent tightening tool is used to determine the tightening position according to the first indicating laser; the monitoring system is used to determine whether the intelligent tightening tool is in the tightening position according to the second indicating laser; the control module is used to control the intelligent tightening tool to perform physical assembly according to the optimal thread assembly connection process parameters when the intelligent tightening tool is in the tightening position.

[0013] In one embodiment, the monitoring system includes: a camera and a reflective surface; the camera is connected to the control module; The reflective surface is disposed on the intelligent tightening tool; the reflective surface is used to receive the second indicator laser; the camera is used to capture the light spot generated on the reflective surface when the second indicator laser shines on the reflective surface, and to determine that the intelligent tightening tool is in the tightening position when the light spot is captured.

[0014] In one embodiment, the monitoring system includes: a sensor; the sensor is connected to the control module; The sensor is mounted on the intelligent tightening tool; the sensor is used to detect the laser energy of the second indicating laser, and when the laser energy is detected, it determines that the intelligent tightening tool is in the tightening position.

[0015] According to the specific embodiments provided in this application, this application has the following technical effects: This application provides a method and monitoring device for optimizing threaded assembly connection process parameters based on precise digital twins. It constructs a geometric distribution error model of the threaded assembly contact surface using surface fitting based on point cloud data of the threaded assembly contact surface. This model is then integrated with the 3D model of the assembled component to obtain a 3D solid model with 3D geometric errors. Similarly, it constructs a 3D bolt model with 3D geometric distribution errors based on bolt point cloud data using surface fitting. A precise geometric digital twin model of the threaded assembly connection structure is then created through virtual assembly of the two 3D solid models and the bolt model. The threaded assembly connection process parameters are optimized based on this precise geometric digital twin model. This application considers error factors in fastening modeling and optimizes parameters through the precise geometric digital twin model of the assembly, improving the accuracy of threaded assembly connection process parameters. This results in high-precision, high-performance products and ultimately achieves industry-wide precision digital twin-based optimization, monitoring, and control of threaded assembly connection process parameters, as well as high-efficiency production. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A flowchart illustrating a method for optimizing process parameters of threaded assembly connections based on precise digital twins, provided in an embodiment of this application; Figure 2 This is a schematic diagram illustrating the integrated design of a three-dimensional geometric distribution error surface and a three-dimensional solid part, as provided in an embodiment of this application. Figure 3 A schematic diagram of error transmission and virtual assembly with geometric distribution error in a threaded assembly connection provided for an embodiment of this application; Figure 4 A schematic diagram of the calculation process for optimizing threaded assembly connection process parameters based on precise digital twins, provided for an embodiment of this application; Figure 5This is a schematic diagram of a real-time monitoring device for the position and sequence of a threaded assembly process, provided in an embodiment of this application.

[0018] Reference numerals: Intelligent tightening tool—1, Tightening position indicator laser emitter—2, Tool position indicator laser emitter—3, Mounted accessory—4, Camera—5, Reflective surface—6. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Currently, the threaded assembly connection process has the following problems: (1) The thread fastening process of most instruments is determined by the workers based on their experience and intuition.

[0022] (2) Some products determine the size of the tightening force when the threaded assembly connection is designed. However, the value is obtained by finite element calculation using an ideal three-dimensional design model. Domestic and foreign studies generally show that the calculation results are very different from the actual physical state. If the threaded assembly connection process is guided by such calculation results, the actual accuracy and performance of the product will have a large error compared with the design target.

[0023] (3) Currently, the standard for judging the magnitude of thread tightening force, both domestically and internationally, is often based on ensuring a reliable connection without material yielding. This often results in excessive tightening force, leading to severe stress concentration within the assembly. Furthermore, the geometric distribution errors that inevitably occur during processing on the assembly contact surface and threaded surface cause local maximum stresses on the assembly contact surface to approach or even exceed the material's yield limit. This problem is the main cause of structural creep and relaxation of internal stress and geometric position after assembly, which inevitably occurs with time, temperature, and external loads. This leads to significant instability in product accuracy and performance. Since current threaded connection assembly process optimization calculations are based on ideal design models and do not consider the influence of geometric distribution errors formed on the assembly contact surface and threaded surface during processing, the optimization results differ significantly from the actual state. The product accuracy, performance, and stability predicted by finite element analysis can mostly only serve as qualitative references.

[0024] (4) Currently, in the optimization process of threaded assembly connections, the recommended torque corresponding to the thread size obtained from the manual is often used as one of the target values, while the yield strength is used as the standard for judging whether the calculated maximum stress is permissible. In fact, such stress values ​​far exceed 60-70% of the stress that produces obvious relaxation, i.e., the yield strength. Therefore, according to the existing algorithm, the optimization has not solved the problem of accuracy and performance stability. A large number of implementation and simulation studies have shown that in threaded assembly connections, when the tightening force is too large and the maximum stress on the assembly contact surface far exceeds 60-70% of the stress that produces obvious relaxation, i.e., the yield strength, the thread is very easy to loosen.

[0025] In the aerospace, aviation, automotive, and machine tool industries, major accidents resulting in mechanical failure and loss of life, as well as generally low product precision and performance, caused by loose threads, are frequently reported both domestically and internationally. Therefore, establishing finite element analysis models that more closely approximate the actual geometry and physical state of electromechanical products, and quantitatively optimizing the threaded assembly connection process parameters of electromechanical products to ensure reliable connections under external loads while preventing significant creep and relaxation issues due to internal contact stress, and to quantitatively control product precision, performance, and stability, are critical bottleneck problems that urgently need to be solved in intelligent manufacturing.

[0026] Therefore, this application uses a precise digital twin model that can accurately characterize the geometry and physical state of the threaded assembly connection structure to optimize the process parameters and control the assembly, thereby solving the above problems.

[0027] In one exemplary embodiment, such as Figure 1 As shown, a method for optimizing threaded assembly connection process parameters based on precise digital twins is provided, including steps 101 to 107. Wherein: Step 101: Obtain point cloud data of the threaded assembly contact surface and bolt point cloud data.

[0028] Step 102: Construct a geometric distribution error model of the thread assembly contact surface based on the point cloud data of the thread assembly contact surface.

[0029] Step 103: Integrate the geometric distribution error model with the three-dimensional model of the assembled part to obtain a three-dimensional solid model with three-dimensional geometric errors.

[0030] Step 104: Construct a 3D model of the bolt with 3D geometric distribution error based on the bolt point cloud data.

[0031] Step 105: Virtually assemble the two three-dimensional solid models and the three-dimensional bolt model to obtain a precise geometric digital twin model of the virtually assembled threaded assembly connection structure.

[0032] Step 106: Input the physical condition data into the precise geometric digital twin model to obtain the precise physical digital twin model of the threaded assembly connection structure.

[0033] The physical condition data includes: static and dynamic environmental data, material data, and nonlinear characteristic data.

[0034] Step 107: Using the precise physical digital twin model, with the accuracy and performance of the physical system after thread fastening as the optimization target, the thread assembly connection process parameters are optimized to obtain the optimal thread assembly connection process parameters.

[0035] Among them, the spatial position and orientation of the assembled parts in the physical system after thread tightening characterize the accuracy of the physical system, and the maximum stress and stress distribution uniformity inside the physical system after thread tightening characterize the performance of the physical system; the threaded assembly connection process parameters include: thread tightening force and tightening sequence.

[0036] In another exemplary embodiment of this application, step 102 specifically includes: constructing a geometric distribution error model of the thread assembly contact surface using the most curved surface fitting method based on the point cloud data of the thread assembly contact surface.

[0037] In another exemplary embodiment of this application, step 105 specifically includes: (1) The two three-dimensional solid models are virtually assembled using a three-point solution algorithm that makes the assembly force within a triangle, resulting in a virtually assembled three-dimensional solid model. Specifically: The two three-dimensional solid models are virtually assembled using a three-point solution algorithm that makes the assembly force within a triangle, resulting in a virtually assembled three-dimensional solid model; the triangle is formed by three contact points determined based on the minimum contact distance of the contact surfaces of the two three-dimensional solid models.

[0038] Specifically, the solution method for the three contact points in the virtual assembly process of two assembly contact surfaces with geometric distribution errors is as follows: 1) Define the contact surface S The point cloud of 1 is Contact surface S The point cloud of 2 is Calculate the surface formed by the minimum distance between two surfaces. Point clouds The calculation formula is as follows: .

[0039] 2) From poor surface point clouds Solving for the contact triangle involves identifying the three contact points. These three points must satisfy two conditions: ① All other points must be below or outside the surface formed by these three points (assuming the assembly contact surface is horizontal) to ensure that the two surfaces do not interfere with each other after assembly. ② The center of gravity (or the point of application of the assembly force) of the assembled parts must be located within the triangle formed by these three points to ensure stable contact between the two assembled parts. That is, if both assembly contact surfaces are horizontal without the application of assembly force, the position of the upper part will not change on its own.

[0040] Let the three contact points be respectively P 1. P 2. P 3. The point on this triangular face where the center of gravity of the assembled part or the point of application of the assembly force is projected is... P c Then determine P c Whether it is within the triangle: as long as it satisfies θ 12 + θ 23 + θ 13 =360°, then, P c It must fall P 1. P 2. P Within the triangle formed by the three angles, the formulas for calculating the three angles are as follows: .

[0041] in, 、 All are in vector form, and their corresponding elements can be represented as , , Let be the coordinates of any point on the contact surface; P 1. P 2. P 3 is composed of , All data in the system are obtained by calculating the contact point through the minimum distance. The contact point can be represented as... , j =1,2,3; i , k =1,2,…, N , N This represents the number of point clouds.

[0042] (2) The three-dimensional solid model after virtual assembly is virtually assembled with the three-dimensional model of the bolt to obtain a precise geometric digital twin model of the threaded assembly connection structure after virtual assembly.

[0043] In another exemplary embodiment of this application, step 107 specifically includes: Using the precise physical digital twin model, the spatial position and orientation of the assembly determined by the user according to the design and process are used as the accuracy constraint target. The maximum stress constraint target is the stress that does not produce significant relaxation, i.e., 60%-70% of the material yield limit (no significant stress relaxation). The uniformity requirement of stress distribution is used as the stress distribution uniformity constraint target. The threaded assembly connection process parameters are optimized to obtain the optimal threaded assembly connection process parameters.

[0044] In another exemplary embodiment of this application, the static and dynamic environmental data includes: temperature, load, and assembly force; the material data includes: data on various material parameters in the threaded assembly connection structure; the material parameters include: elastic modulus, Poisson's ratio, and coefficient of linear expansion, etc.; the nonlinear characteristic data includes: stress relaxation data, structural creep data, and friction data within the physical system.

[0045] In another exemplary embodiment of this application, after step 107, the method for optimizing threaded assembly connection process parameters based on precise digital twins further includes: determining the number of threaded assembly fastening feed threads and the thread diameter based on the thread fastening force in the optimal threaded assembly connection process parameters.

[0046] In this embodiment, once the thread tightening force is determined, the thread tightening parameters can be selected and set by the user according to the tightening force requirements, without the need for further optimization calculations.

[0047] The following section provides a more detailed explanation of the above-mentioned method for optimizing the process parameters of threaded assembly connections based on precise digital twins.

[0048] The thread assembly connection process parameter optimization method based on precise digital twin in this embodiment mainly includes: a method for integrating three-dimensional geometric distribution error surface with three-dimensional solid part, a method for error transmission and virtual assembly of thread assembly connection with geometric distribution error, and a calculation process for optimizing thread assembly connection process parameters based on precise digital twin.

[0049] The integrated method of three-dimensional geometric distribution error surface and three-dimensional solid part mainly includes three parts: geometric distribution error model of threaded assembly contact surface, ideal three-dimensional model of the assembled part, and integrated three-dimensional solid model with three-dimensional geometric error, such as... Figure 2 As shown; the three-dimensional geometric distribution error model of the assembly contact surface and threaded surface is proposed to be obtained by using point cloud data obtained from the contact surface measurement through methods such as high-order least squares surface fitting or B-spline surface fitting.

[0050] Among them, the error transmission and virtual assembly method for threaded assembly connections with geometric distribution errors mainly includes: an integrated 3D model 1 with 3D geometric errors, an integrated 3D model 2 with 3D geometric errors, an integrated 3D model of bolts with 3D geometric distribution errors, and a precise geometric digital twin model of the assembly obtained after virtual assembly of the above three types of parts on a computer, such as... Figure 3 As shown; the virtual assembly of the contact surfaces of two integrated 3D models with 3D geometric errors is to be implemented using the difference surface method by directly calculating the positive and negative height differences between the two contacting error surfaces, or the minimum potential energy principle calculated by the height of each point on the upper surface from the lower surface, as the pose algorithm after virtual assembly. The resulting 3D solid model, which is geometrically closest to the real threaded connection assembly system, is obtained by virtually assembling the integrated 3D model 1 with 3D geometric errors, the integrated 3D model 2 with 3D geometric errors, and the bolt integrated 3D model with 3D geometric distribution errors. This is the precise geometric digital twin model of the corresponding system.

[0051] Among them, such as Figure 4 As shown, the optimization calculation process for threaded assembly connection process parameters based on precise digital twins mainly includes: modeling of contact surface geometric errors, virtual assembly and geometric digital twin modeling of the assembled parts with contact surface geometric distribution errors on a computer, physical condition setting, precise physical digital twin modeling, optimization parameter setting, physical property prediction, optimization result evaluation, output, and judgment. Among these, physical condition setting refers to the variation laws of various material parameters, mechanical parameters, and working environment parameters within the threaded connection assembly, including nonlinear parameters such as creep, relaxation, and friction. These physical conditions are applied to the precise geometric digital twin model, thus obtaining the precise physical digital twin model of the corresponding physical system. One of the optimization objectives, the evaluation of the maximum stress on the assembly contact surface, uses 60-70% of the yield strength (stress that does not produce significant relaxation) as the evaluation standard.

[0052] The specific optimization process is as follows: (1) Based on the measurement and data processing of the threaded assembly contact surface, including the assembly contact surface of the connected parts, the threaded connecting parts such as the external thread surface of the bolt and the internal thread surface of the nut, the lower end face of the bolt and nut, the end face of the nut, etc., a precise three-dimensional geometric distribution error model of the measured surface is established, and it can be converted into a data format that can be integrated with various CAD systems, and integrated with the three-dimensional design model to obtain a three-dimensional solid model of the parts with real dimensions and geometric errors; (2) The three-dimensional solid model of the parts with real dimensions and errors is used to perform virtual assembly of each connected part and each threaded connecting part with errors through assembly surface error transmission calculation, to obtain a precise geometric digital twin model that is as consistent as possible with the physical system of the threaded fastening connection in terms of macro- and micro-geometric morphology; (3) The threaded fastening connection is used to perform virtual assembly of each connected part and each threaded connecting part with errors. The static and dynamic environmental data of the external environment of the physical system from assembly to use, including temperature, load, assembly force and other factors, and the nonlinear characteristics data of stress relaxation, structural creep and friction of the physical system are brought into the above-mentioned precise geometric digital twin model to obtain a precise digital twin model whose linear and nonlinear variation characteristics are as consistent as possible with the physical system of the threaded fastening connection; (4) Taking the target accuracy and performance of the physical system of the threaded fastening connection as the optimization target, the maximum internal stress of the physical system after thread fastening is one of the performance optimization targets. The threaded assembly connection process parameters (thread fastening force, tightening sequence) are used as optimization variables. The precise digital twin model of the physical system of the threaded fastening connection is used as the calculation model to perform optimization iteration calculation and complete the optimization calculation of the threaded assembly connection process parameters.

[0053] The above-mentioned method for optimizing the process parameters of threaded assembly connection based on precise digital twins mainly includes: (1) storing the three-dimensional geometric distribution error model software of the threaded assembly contact surface (including the contact surface of the connected parts, the threaded connection parts such as the external thread surface of the bolt and the internal thread surface of the nut, the lower end face of the bolt and nut, the end face of the nut, etc.) in the computer; (2) integrating the stored three-dimensional geometric distribution error model and internal and external environment model data with the three-dimensional solid model or finite element calculation model in the computer to establish and perform a precise digital twin model of the physical system of the threaded fastening connection; (3) transmitting the threaded fastening connection process parameters obtained by optimization calculation to the intelligent tightening tool on the production line through the network, and achieving precise control of the optimized parameters and process through the on-site intelligent monitoring device and the intelligent tightening tool.

[0054] Based on the same inventive concept, embodiments of this application also provide a real-time monitoring device for the position and sequence of a threaded assembly process, such as... Figure 5As shown, it includes: a computer system for integrating and processing data of the thread assembly process and a real-time monitoring device for the position and sequence of the intelligent tightening process; the computer system for integrating and processing data of the thread assembly process is connected to the real-time monitoring device for the position and sequence of the intelligent tightening process; the computer system for integrating and processing data of the thread assembly process and the real-time monitoring device for the position and sequence of the intelligent tightening process have a real-time data transmission function.

[0055] The computer system for integrating and processing data during the thread assembly process includes: The data acquisition module is used to acquire point cloud data of the threaded assembly contact surface and bolt point cloud data.

[0056] The module for constructing a geometric distribution error model of the threaded assembly contact surface is used to construct a geometric distribution error model of the threaded assembly contact surface based on the point cloud data of the threaded assembly contact surface.

[0057] The 3D model integration module is used to integrate the geometric distribution error model with the 3D model of the assembled parts to obtain a 3D solid model with 3D geometric errors.

[0058] The bolt 3D model construction module is used to construct a bolt 3D model with 3D geometric distribution error based on the bolt point cloud data.

[0059] The virtual assembly module is used to virtually assemble the two three-dimensional solid models and the three-dimensional bolt model to obtain a precise geometric digital twin model of the threaded assembly connection structure after virtual assembly.

[0060] The precise physical digital twin model construction module is used to input physical condition data into the precise geometric digital twin model to obtain a precise physical digital twin model of the threaded assembly connection structure; the physical condition data includes: static and dynamic environmental data, material data, and nonlinear characteristic data.

[0061] The parameter optimization module is used to optimize the threaded assembly connection process parameters by using the precise physical digital twin model, with the accuracy and performance of the physical system after thread fastening as the optimization target, so as to obtain the optimal threaded assembly connection process parameters.

[0062] Among them, the spatial position and orientation of the assembled parts in the physical system after thread tightening characterize the accuracy of the physical system, and the maximum stress and stress distribution uniformity inside the physical system after thread tightening characterize the performance of the physical system; the threaded assembly connection process parameters include: thread tightening force and tightening sequence.

[0063] The data transmission module is used to send the optimal threaded assembly connection process parameters to the intelligent tightening process position and sequence real-time monitoring device, and at the same time receive feedback data on the execution results of the intelligent tightening process position and sequence in real time.

[0064] The intelligent tightening process position and sequence real-time monitoring device is used to assemble the physical object according to the optimal thread assembly connection process parameters.

[0065] As an optional implementation, please still refer to Figure 5 The intelligent tightening process position and sequence real-time monitoring device includes: an intelligent tightening tool 1, a tightening position indicating laser emitting device 2, a tool position indicating laser emitting device 3, and a monitoring system; the thread assembly process data integration and processing computer system further includes: a control module; the monitoring system and the intelligent tightening tool 1 are both connected to the control module.

[0066] The tightening position indicating laser emitting device 2 is used to emit a first indicating laser to indicate the threaded hole on the assembled part; the tool position indicating laser emitting device 3 is used to emit a second indicating laser to indicate the position of the intelligent tightening tool 1; the intelligent tightening tool 1 is used to determine the tightening position according to the first indicating laser; the monitoring system is used to determine whether the intelligent tightening tool 1 is in the tightening position according to the second indicating laser; the control module is used to control the intelligent tightening tool 1 to perform physical assembly of the assembled part 4 according to the optimal thread assembly connection process parameters when the intelligent tightening tool 1 is in the tightening position.

[0067] As an optional implementation, please still refer to Figure 5 The monitoring system includes: a camera 5 and a reflective surface 6; the camera 5 is connected to the control module; the reflective surface 6 is disposed on the intelligent tightening tool 1; the reflective surface 6 is used to receive the second indicator laser; the camera 5 is used to capture the light spot generated on the reflective surface 6 when the second indicator laser irradiates the reflective surface 6, and to determine that the intelligent tightening tool 1 is in a tightening position when the light spot is captured.

[0068] In one embodiment, the monitoring system includes: a sensor; the sensor is connected to the control module. The sensor is mounted on the intelligent tightening tool 1, and the sensor replaces... Figure 5 The position of the reflective surface 6; the sensor is used to detect the laser energy of the second indicating laser, and when the laser energy is detected, it is determined that the intelligent tightening tool 1 is in the tightening position.

[0069] This embodiment, along with the monitoring system comprised of camera 5 and reflective surface 6, represents two different implementation methods. In practical applications, the choice can be made independently.

[0070] As an optional implementation, the intelligent tightening process position and sequence real-time monitoring device further includes: a first gimbal and a second gimbal; a tightening position indicating laser emitting device 2 is provided on the first gimbal; and a tool position indicating laser emitting device 3 is provided on the second gimbal.

[0071] The method and monitoring device for optimizing threaded assembly connection process parameters based on precise digital twins in this application are mainly reflected in the following aspects: (1) The target accuracy index of the physical system of threaded fastening connection, the maximum stress inside the structure and the uniformity of stress distribution are used as evaluation indicators for optimizing the process parameters of threaded assembly connection. (2) Different fastening connection process parameters and fastening sequence data for each thread are obtained through the optimization calculation of threaded assembly connection process parameters based on precise digital twins. Even for threads of the same specification and accuracy grade, their fastening connection process parameters will be different. (3) The three-dimensional space of the physical system of threaded assembly connection and the different fastening connection process parameters and fastening sequence data for each thread obtained after optimization are used to construct a precise geometric digital twin model for threaded assembly connection process control in a computer. The model marks all thread fastening positions, sequences and magnitudes. (4) The precise geometric digital twin model data for threaded assembly connection process control and the physical system of threaded assembly connection constitute a pair of precise digital twins and are transmitted to the control module of the intelligent tightening tool to control all thread fastening positions, sequences and magnitudes marked in the model in real time.

[0072] The real-time monitoring device for the position and sequence of the thread assembly process in the above embodiment realizes the monitoring and control of the thread fastening force process based on precise digital twins. It is mainly reflected in: (1) The on-site intelligent monitoring and control device for the thread assembly connection process includes two or more laser beam and spot recognition cameras arranged above the physical system of the thread assembly connection, which automatically match and track the threaded hole and the intelligent tightening tool respectively. (2) A plane (i.e., a reflective surface) that can receive laser spot is installed on the body of the intelligent tightening tool. When the camera captures the spot, the control module controls the intelligent tightening tool to start, otherwise it is locked. (3) A sensor that can receive laser energy is installed on the intelligent tightening tool. When the sensor receives the tool monitoring signal, the control module controls the intelligent tightening tool to start, otherwise it is locked.

[0073] This application presents a method and monitoring device for optimizing thread assembly connection process parameters based on precise digital twins. Through an integrated method of three-dimensional geometric distribution error surface and three-dimensional solid part, a method for transmitting thread assembly connection error with geometric distribution error and virtual assembly, and a calculation process for optimizing thread assembly connection process parameters based on precise digital twins, it realizes the monitoring and control of thread fastening force process based on precise digital twins, and ultimately achieves optimized monitoring and control of thread fastening force and high-efficiency production in the industry.

[0074] The method and monitoring device for optimizing threaded assembly connection process parameters based on precise digital twins in this application builds upon previous work and integrates them into a unified whole, ultimately achieving the goal of optimizing and monitoring the threaded assembly connection process parameters based on precise digital twins.

[0075] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0076] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for optimizing process parameters of threaded assembly connections based on precise digital twins, characterized in that, include: Acquire point cloud data of the threaded assembly contact surface and bolt point cloud data; A geometric distribution error model of the thread assembly contact surface is constructed based on the point cloud data of the thread assembly contact surface. The geometric distribution error model is integrated with the three-dimensional model of the assembled part to obtain a three-dimensional solid model with three-dimensional geometric errors. A 3D model of the bolt with 3D geometric distribution error is constructed based on the bolt point cloud data; The two three-dimensional solid models and the three-dimensional bolt model are virtually assembled to obtain an accurate geometric digital twin model of the threaded assembly connection structure after virtual assembly. By inputting the physical condition data into the precise geometric digital twin model, a precise physical digital twin model of the threaded assembly connection structure is obtained; the physical condition data includes: static and dynamic environmental data, material data, and nonlinear characteristic data; Using the precise physical digital twin model, with the accuracy and performance of the physical system after thread fastening as the optimization target, the thread assembly connection process parameters are optimized to obtain the optimal thread assembly connection process parameters. Among them, the spatial position and orientation of the assembled parts in the physical system after thread tightening characterize the accuracy of the physical system, and the maximum stress and stress distribution uniformity inside the physical system after thread tightening characterize the performance of the physical system; the threaded assembly connection process parameters include: thread tightening force and tightening sequence.

2. The method for optimizing threaded assembly connection process parameters based on precise digital twins according to claim 1, characterized in that, Based on the point cloud data of the threaded assembly contact surface, a geometric distribution error model of the threaded assembly contact surface is constructed, specifically including: Based on the point cloud data of the threaded assembly contact surface, a geometric distribution error model of the threaded assembly contact surface is constructed using a surface fitting method.

3. The method for optimizing threaded assembly connection process parameters based on precise digital twins according to claim 1, characterized in that, The two 3D solid models and the bolt 3D model are virtually assembled to obtain a precise geometric digital twin model of the virtually assembled threaded connection structure, specifically including: A three-point solution algorithm that makes the assembly force within a triangle is used to virtually assemble the two three-dimensional solid models to obtain the virtual assembled three-dimensional solid model; the triangle is formed by three contact points determined based on the minimum contact distance between the contact surfaces of the two three-dimensional solid models; The three-dimensional solid model after virtual assembly is virtually assembled with the three-dimensional model of the bolt to obtain an accurate geometric digital twin model of the threaded assembly connection structure after virtual assembly.

4. The method for optimizing threaded assembly connection process parameters based on precise digital twins according to claim 1, characterized in that, Using the aforementioned precise physical digital twin model, and taking the accuracy and performance of the physical system after thread fastening as the optimization objective, the threaded assembly connection process parameters are optimized to obtain the optimal threaded assembly connection process parameters, specifically including: Using the precise physical digital twin model, the spatial position and orientation of the assembly determined by the user according to the design and process are used as the accuracy constraint target, 60%-70% of the material yield limit is used as the maximum stress constraint target, and the uniformity requirement of stress distribution is used as the stress distribution uniformity constraint target. The threaded assembly connection process parameters are optimized to obtain the optimal threaded assembly connection process parameters.

5. The method for optimizing threaded assembly connection process parameters based on precise digital twins according to claim 1, characterized in that, The static and dynamic environmental data include: temperature, load, and assembly force; the material data includes: data on various material parameters in the threaded assembly connection structure; the material parameters include: elastic modulus, Poisson's ratio, and coefficient of linear expansion; the nonlinear characteristic data includes: stress relaxation data, structural creep data, and friction data within the physical system.

6. The method for optimizing threaded assembly connection process parameters based on precise digital twins according to claim 1, characterized in that, After obtaining the optimal threaded assembly connection process parameters, the threaded assembly connection process parameter optimization method based on accurate digital twins further includes: Based on the thread tightening force in the optimal thread assembly connection process parameters, determine the number of threads and the thread diameter for thread assembly tightening feed.

7. A real-time monitoring device for the position and sequence of a threaded assembly process, characterized in that, The real-time monitoring device for the position and sequence of the thread assembly process includes: a computer system for integrating and processing data of the thread assembly process and a real-time monitoring device for the position and sequence of the intelligent tightening process; the computer system for integrating and processing data of the thread assembly process and the real-time monitoring device for the position and sequence of the intelligent tightening process have real-time data transmission capabilities. The computer system for integrating and processing data during the thread assembly process includes: The data acquisition module is used to acquire point cloud data of the threaded assembly contact surface and bolt point cloud data; The geometric distribution error model construction module for the threaded assembly contact surface is used to construct a geometric distribution error model for the threaded assembly contact surface based on the point cloud data of the threaded assembly contact surface. A 3D model integration module is used to integrate the geometric distribution error model with the 3D model of the assembled parts to obtain a 3D solid model with 3D geometric errors. A bolt 3D model construction module is used to construct a bolt 3D model with 3D geometric distribution error based on the bolt point cloud data; The virtual assembly module is used to virtually assemble the two three-dimensional solid models and the three-dimensional bolt model to obtain a precise geometric digital twin model of the threaded assembly connection structure after virtual assembly. The precise physical digital twin model construction module is used to input physical condition data into the precise geometric digital twin model to obtain a precise physical digital twin model of the threaded assembly connection structure; the physical condition data includes: static and dynamic environmental data, material data, and nonlinear characteristic data; The parameter optimization module is used to optimize the threaded assembly connection process parameters by using the precise physical digital twin model, with the accuracy and performance of the physical system after thread fastening as the optimization target, so as to obtain the optimal threaded assembly connection process parameters. Among them, the spatial position and orientation of the assembled parts in the physical system after thread tightening characterize the accuracy of the physical system, and the maximum stress and stress distribution uniformity inside the physical system after thread tightening characterize the performance of the physical system; the threaded assembly connection process parameters include: thread tightening force and tightening sequence. The data transmission module is used to send the optimal threaded assembly connection process parameters to the intelligent tightening process position and sequence real-time monitoring device, and at the same time receive feedback data on the execution results of the intelligent tightening process position and sequence in real time. The intelligent tightening process position and sequence real-time monitoring device is used to assemble the physical object according to the optimal thread assembly connection process parameters.

8. The real-time monitoring device for the position and sequence of the thread assembly process according to claim 7, characterized in that, The intelligent tightening process position and sequence real-time monitoring device includes: an intelligent tightening tool, a tightening position indicating laser emitting device, a tool position indicating laser emitting device, and a monitoring system; the thread assembly process data integration and processing computer system further includes: a control module; the monitoring system and the intelligent tightening tool are both connected to the control module; The tightening position indicating laser emitting device is used to emit a first indicating laser to indicate the threaded hole on the assembled part; the tool position indicating laser emitting device is used to emit a second indicating laser to indicate the position of the intelligent tightening tool; the intelligent tightening tool is used to determine the tightening position according to the first indicating laser; the monitoring system is used to determine whether the intelligent tightening tool is in the tightening position according to the second indicating laser; the control module is used to control the intelligent tightening tool to perform physical assembly according to the optimal thread assembly connection process parameters when the intelligent tightening tool is in the tightening position.

9. The real-time monitoring device for the position and sequence of the thread assembly process according to claim 8, characterized in that, The monitoring system includes: a camera and a reflective surface; the camera is connected to the control module; The reflective surface is disposed on the intelligent tightening tool; the reflective surface is used to receive the second indicator laser; the camera is used to capture the light spot generated on the reflective surface when the second indicator laser shines on the reflective surface, and to determine that the intelligent tightening tool is in the tightening position when the light spot is captured.

10. The real-time monitoring device for the position and sequence of the thread assembly process according to claim 8, characterized in that, The monitoring system includes: a sensor; the sensor is connected to the control module; The sensor is mounted on the intelligent tightening tool; the sensor is used to detect the laser energy of the second indicating laser, and when the laser energy is detected, it determines that the intelligent tightening tool is in the tightening position.

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