Frame assembly dimensional tolerance design method, electronic equipment and storage medium

Abstract

The invention belongs to the technical field of commercial vehicle chassis design, and discloses a vehicle frame assembly dimensional tolerance design method, electronic equipment and a storage medium, and the method comprises the steps: S1, size problem identification: decoupling the size problem affecting the whole vehicle installation and quality problem, determining the whole vehicle key size related to the quality problem, and carrying out the recognition of the size problem; identifying the key size of the frame assembly from the listed key sizes of the whole vehicle; s2, design optimization of the size precision of the frame assembly: identifying the current situation of the key size precision of the frame assembly, setting a key size precision target of the frame assembly, and analyzing and optimizing the key size of the frame assembly to achieve the precision target; and S3, completing improvement and summarization. The invention designs a method for designing the dimensional tolerance of a frame assembly, which is used for solving the problems of assembly, performance and reliability caused by unreasonable traditional tolerance design, and improves the dimensional accuracy of a frame and the structural performance and quality of a whole vehicle by optimizing the design of a frame dimensional chain.

Description

Technical Field

[0001] This invention belongs to the field of commercial vehicle chassis design technology, specifically relating to a method for designing dimensional tolerances of a vehicle frame assembly, electronic equipment, and storage medium. Background Technology

[0002] As the load-bearing base and assembly benchmark of a vehicle, the chassis's overall dimensional accuracy directly determines the installation accuracy and fit quality of key assemblies such as the suspension, cab, axles, and steering system. It is a core element in ensuring the consistency of vehicle assembly, driving stability, and reliability. Chassis dimensional deviations not only cause manufacturing problems such as component assembly interference, installation alignment difficulties, and low assembly efficiency, but also directly lead to functional failures such as vehicle misalignment, abnormal tire wear, driving vibration, and cab misalignment. These deviations significantly reduce the structural strength, durability, and service life of the vehicle, affecting driving safety and the driving experience.

[0003] With the development of lightweight, high-load-bearing, and long-life automotive technologies, vehicle frames are mostly formed by stamping and welding high-strength steel plates. The manufacturing process involves multiple steps, including stamping, welding deformation, tooling positioning, heat treatment, and machining, resulting in a long dimensional transfer chain and significant error accumulation effects. Currently, the industry's definition and allocation of tolerances for vehicle frame assemblies and components generally rely on historical experience, benchmarking data, or subjective judgment, lacking a systematic tolerance decomposition and optimization method that matches actual manufacturing processes, assembly constraints, and overall vehicle performance requirements. Existing tolerance designs suffer from problems such as tolerance redundancy, overly loose critical dimensions, overly tight non-critical dimensions, unreasonable dimensional chain closures, and mismatch with process capabilities. These issues make it difficult to control error transmission and accumulation at the source, and cannot effectively support high-precision vehicle frame manufacturing and overall vehicle performance compliance.

[0004] Therefore, there is an urgent need for a method for tolerance decomposition, allocation, and optimization to solve the assembly, performance, and reliability problems caused by unreasonable traditional tolerance design. Summary of the Invention

[0005] This invention provides a method for designing dimensional tolerances of a vehicle frame assembly, an electronic device, and a storage medium. Targeting the vehicle frame assembly and considering actual manufacturing processes, it addresses assembly, performance, and reliability issues caused by unreasonable traditional tolerance designs. By optimizing the frame dimensional chain design, it improves the dimensional accuracy of the frame and enhances the overall structural performance and quality of the vehicle.

[0006] The specific details of the plan are as follows:

[0007] A method for designing dimensional tolerances for a vehicle frame assembly, comprising the following steps:

[0008] S1. Size problem identification: Decouple size problems that affect vehicle installation and quality, identify key vehicle dimensions related to quality problems, and identify key dimensions of the chassis assembly from the identified key vehicle dimensions;

[0009] S2. Chassis assembly dimensional accuracy design optimization: Identify the current status of the critical dimension accuracy of the chassis assembly, set the critical dimension accuracy target for the chassis assembly, and analyze and optimize the critical dimensions of the chassis assembly to achieve the accuracy target;

[0010] S3. Complete the improvements and summarize.

[0011] Furthermore, step S1 includes:

[0012] S11. Based on the DFMEA complex problem analysis approach, identify vehicle installation and quality issues and analyze the parts related to the vehicle's critical dimension chain;

[0013] S12. Identify and list all critical dimensions of the vehicle that are relevant to installation and quality issues;

[0014] S13. Based on the listed key dimensions of the whole vehicle, identify the key dimensions of the chassis assembly and classify them into two categories: Category A and Category B. Category A consists of key dimensions that need further decomposition, while Category B consists of key dimensions that do not need further decomposition.

[0015] Furthermore, step S2 includes:

[0016] S21. Identification of the current status of critical dimension accuracy of the chassis assembly: Based on the measurement of the critical dimension data of the chassis assembly of the current production model, the data is then compared with the theoretical dimensions to obtain the current status of the dimension qualification rate;

[0017] S22. Target setting for critical dimensions of the chassis assembly: Set target for the pass rate of critical dimensions of the chassis based on standards, regulations, experience, or benchmarking.

[0018] S23. Achievement of critical dimension accuracy targets for chassis assembly: Define the closed loop of the dimension chain, and analyze the achievement paths for Class A and Class B critical dimension accuracy based on experience and benchmarking methods.

[0019] Furthermore, in step S21, the identification of the current accuracy status of key dimensions of the chassis assembly includes:

[0020] In step S21, the identification of the current accuracy status of key dimensions of the chassis assembly includes:

[0021] S2111. Based on actual measurements, derive the key dimensions of the Class A frame assembly of interest;

[0022] S2112. Confirmation of theoretical tolerances for critical dimensions of chassis assembly: Based on benchmarking results, project inputs and vehicle manufacturing and assembly requirements, confirm the theoretical tolerance values ​​for critical dimensions of Class A chassis assembly.

[0023] S2113, Statistical Analysis of Critical Dimension Pass Rate of Chassis Assembly: Based on the chassis of currently produced models, the actual measurement of critical dimensions of Class A chassis assemblies is conducted to obtain all measured values. The difference between the measured values ​​and the benchmark values ​​is used to obtain the actual tolerance. The actual tolerance is then compared with the theoretical tolerance to determine the number of data that meet the theoretical tolerance. This is achieved through a formula... The pass rate is calculated.

[0024] Furthermore, in step S22, the specific method for setting the target for the pass rate of key dimensions of the chassis by benchmarking is to measure the key dimensions of the chassis of internationally advanced commercial vehicle companies, find the gaps by benchmarking, and set the target for the pass rate of key dimensions of the chassis.

[0025] Furthermore, in step S23, the path to achieve the accuracy of the critical dimension for category A includes:

[0026] S2311. Identify the closed loop of the dimensional chain that has a significant impact on the critical dimensions of the chassis assembly: By performing loop sensitivity analysis on the dimensional chain, select the closed loop of the dimensional chain that has a significant impact on the critical dimensions based on the sensitivity analysis results;

[0027] S2312, Dimensional Chain Analysis and Tolerance Allocation Verification of Chassis Assembly: Clarify the accuracy requirements of the selected dimensional chain closing loop, analyze the component loops of the dimensional chain, and verify the tolerance of the closing loop;

[0028] S2313, Measures to improve the dimensional accuracy of the frame assembly: Considering the reduction of component rings, reasonable dimension marking, process implementation capability, and hole pin floating methods, the tolerance optimization is carried out by comprehensively considering cost control and process stability during the process of achieving the tolerance of component rings, and the 3DCS dimensional engineering software is used for verification and analysis.

[0029] Furthermore, in step S23, the path to achieve the critical dimension accuracy of category B is based on the measures to achieve dimension accuracy and complete experimental verification, including benchmark standardization, improvement of part dimension accuracy, improvement of process tooling applicability, and maintenance of dimension accuracy.

[0030] Furthermore, in step S3, a comparative analysis of actual results is conducted to complete the drawing improvement and the accumulation of dimensional tolerance design for the chassis assembly.

[0031] An electronic device includes a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; the memory is used to store computer programs; and the processor is used to implement the frame assembly dimensional tolerance design method when executing the program stored in the memory.

[0032] A storage medium having a computer program stored thereon, which is executed by a processor to implement the aforementioned chassis assembly dimensional tolerance design method.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] This invention addresses the chassis assembly by designing a tolerance decomposition, allocation, and optimization method based on actual manufacturing processes. This method is used to support and resolve issues related to the overall vehicle structure and performance dimensions caused by the dimensional chain, thereby improving the chassis dimensional accuracy and enhancing the overall vehicle structural performance and quality. Attached Figure Description

[0035] Figure 1 This is a flowchart of the frame assembly dimensional tolerance design method of the present invention.

[0036] Figure 2 This is a curve obtained by fitting the simulation data record table of the front spring front bracket crossbeam welding assembly deviation in Example 2.

[0037] Figure 3 This is a curve obtained by fitting the simulation data record table of the deviation of a crossbeam assembly in the stamping process in Example 2.

[0038] Figure 4 This is a schematic diagram of the outer width design dimension chain of a crossbeam frame in Example 2 during stamping.

[0039] Figure 5 This is a schematic diagram of the dimension chain of a crossbeam structure in the optimized integral casting of Example 2. Detailed Implementation

[0040] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. Furthermore, it should be noted that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings, not all of them.

[0041] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions.

[0042] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0043] The following examples are combined Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 The present invention will be described in detail below.

[0044] Example 1:

[0045] A method for designing dimensional tolerances for a vehicle frame assembly, see Figure 1 As shown, the steps include:

[0046] S1. Size problem identification: Decouple size problems that affect vehicle installation and quality, identify key vehicle dimensions related to quality problems, and identify key dimensions of the chassis assembly from the identified key vehicle dimensions;

[0047] S2. Chassis assembly dimensional accuracy design optimization: Identify the current status of the critical dimension accuracy of the chassis assembly, set the critical dimension accuracy target for the chassis assembly, and analyze and optimize the critical dimensions of the chassis assembly to achieve the accuracy target;

[0048] S3. Complete the improvements and summarize.

[0049] Step S1 includes:

[0050] S11. Based on the DFMEA complex problem analysis approach, identify vehicle installation and quality issues and analyze the parts related to the vehicle's critical dimension chain;

[0051] S12. Identify and list all critical dimensions of the vehicle that are relevant to installation and quality issues;

[0052] S13. Based on the listed key dimensions of the whole vehicle, identify the key dimensions of the chassis assembly and classify them into two categories: Category A and Category B. Category A consists of key dimensions that need further decomposition, while Category B consists of key dimensions that do not need further decomposition.

[0053] Step S2 includes:

[0054] S21. Identification of the current status of critical dimension accuracy of the chassis assembly: Based on the measurement of the critical dimension data of the chassis assembly of the current production model, the data is then compared with the theoretical dimensions to obtain the current status of the dimension qualification rate;

[0055] S22. Target setting for critical dimensions of the chassis assembly: Set target for the pass rate of critical dimensions of the chassis based on standards, regulations, experience, or benchmarking.

[0056] S23. Achievement of critical dimension accuracy targets for chassis assembly: Define the closed loop of the dimension chain, and analyze the achievement paths for Class A and Class B critical dimension accuracy based on experience and benchmarking methods.

[0057] In step S21, the identification of the current accuracy status of key dimensions of the chassis assembly includes:

[0058] S2111. Based on actual measurements, derive the key dimensions of the Class A frame assembly of interest;

[0059] S2112. Confirmation of theoretical tolerances for critical dimensions of chassis assembly: Based on benchmarking results, project inputs and vehicle manufacturing and assembly requirements, confirm the theoretical tolerance values ​​for critical dimensions of Class A chassis assembly.

[0060] S2113, Statistical Analysis of Critical Dimension Pass Rate of Chassis Assembly: Based on the chassis of currently produced models, the actual measurement of critical dimensions of Class A chassis assemblies is conducted to obtain all measured values. The difference between the measured values ​​and the benchmark values ​​is used to obtain the actual tolerance. The actual tolerance is then compared with the theoretical tolerance to determine the number of data that meet the theoretical tolerance. This is achieved through a formula... The pass rate is calculated.

[0061] In step S22, the specific method for setting the target for the pass rate of key dimensions of the chassis by benchmarking is to measure the key dimensions of the chassis of internationally advanced commercial vehicle companies, find the gaps by benchmarking, and set the target for the pass rate of key dimensions of the chassis.

[0062] In step S23, the path to achieving the accuracy of critical dimensions for category A includes:

[0063] S2311. Identify the closed loop of the dimensional chain that has a significant impact on the critical dimensions of the chassis assembly: By performing loop sensitivity analysis on the dimensional chain, select the closed loop of the dimensional chain that has a significant impact on the critical dimensions based on the sensitivity analysis results;

[0064] S2312, Dimensional Chain Analysis and Tolerance Allocation Verification of Chassis Assembly: Clarify the accuracy requirements of the selected dimensional chain closing loop, analyze the component loops of the dimensional chain, and verify the tolerance of the closing loop;

[0065] S2313, Measures to improve the dimensional accuracy of the frame assembly: Considering the reduction of component rings, reasonable dimension marking, process implementation capability, and hole pin floating methods, the tolerance optimization is carried out by comprehensively considering cost control and process stability during the process of achieving the tolerance of component rings, and the 3DCS dimensional engineering software is used for verification and analysis.

[0066] In step S23, the path to achieve the critical dimension accuracy of category B is based on the measures to achieve dimension accuracy and complete experimental verification, including benchmark standardization, improvement of part dimension accuracy, improvement of process tooling applicability, and maintenance of dimension accuracy.

[0067] In step S3, a comparative analysis of actual results is conducted to complete the drawing improvement and accumulate design knowledge on the dimensional tolerances of the chassis assembly.

[0068] Example 2:

[0069] This embodiment uses the frame assembly dimensional tolerance design method of the present invention to solve the problem of tire wear and vehicle misalignment.

[0070] S1, Size Problem Identification Stage:

[0071] S11. Decoupling of Dimensional Issues: Based on the DFMEA approach to complex problem analysis, analyze the dimensional issues related to tire wear and vehicle misalignment. For dimensional issues, analyze the parts related to the vehicle's key dimensional chain.

[0072] S12. Define key vehicle dimensions: The project lists 26 key vehicle dimensions related to tire wear and vehicle misalignment.

[0073] S13. Identification of Key Dimensions of the Chassis Assembly: From the 26 listed key dimensions of the entire vehicle, identify the key dimensions of the chassis assembly. These key dimensions are divided into two categories: Category A, which requires further decomposition (focusing on the outer width of the chassis), and Category B, which does not require further decomposition. Specifically, L1 at the front-end module of the chassis and L2 at the point from the front engine mount to the rear cab mount are both Category A, meaning they are key chassis dimensions requiring further decomposition.

[0074] S2. Optimize the dimensional accuracy design of the chassis assembly, specifically including:

[0075] S21. Identification of the current status of critical dimension accuracy of the chassis assembly: Based on the measurement of the critical dimension data of the chassis assembly of the current production model, the data is then compared with the theoretical dimensions to obtain the current status of the dimension qualification rate;

[0076] S2111, Key dimensions of the chassis assembly:

[0077] Based on the measurements of the frame mounting holes, the key dimensions of the frame assembly of interest are derived. Among the key dimensions of the frame at the rear cab mounting location, three key dimensions can be derived: DX0050 (X-direction two-point difference), DY0050 (Y-direction two-point difference), and DZ0050 (Z-direction two-point difference). Among them, the Class A key dimension DY0050 is the L2 frame key dimension from the front engine mount to the rear cab mounting location, which is the focus of the tire wear and lane deviation project.

[0078] S2112, Confirmation of theoretical tolerances for critical dimensions of the chassis assembly: Based on benchmarking results, project inputs, and vehicle manufacturing and assembly requirements, the Technology Development Department confirmed the theoretical tolerance values ​​for the critical dimension L2 of the chassis assembly, as shown in Table 1.

[0079] Table 1

[0080]

[0081] S2113 chassis assembly key dimension pass rate statistics:

[0082] Based on the J7 current production model chassis 2800010-2051, the coordinates of the mounting holes HILT0050 and HIRT0050 at the rear suspension of the cab were measured using a coordinate measuring machine. The measurement period was from December 2021 to November 2022; the number of measurements was 105 vehicles. Based on the mounting hole coordinates, the measured values ​​of 105 key dimensions L2 can be derived. Subtracting the measured values ​​from the baseline values ​​yields the actual tolerances of the 105 key dimensions L2. Comparing the actual tolerances with the theoretical tolerances reveals the number of data points that meet the theoretical tolerances. This can be further verified using a formula. The pass rate was calculated, and the pass rate for the critical frame dimension L2 was found to be 68.42%.

[0083] S22. Target settings for critical dimensions of the chassis assembly:

[0084] We measured the critical dimension L2 of the chassis of internationally advanced commercial vehicle manufacturers, identified gaps by benchmarking, and set targets, setting the pass rate of our company's critical dimension L2 at 98%.

[0085] S23, Key Dimensional Precision Targets for Chassis Assembly Achieved:

[0086] There are two main closed loops in the dimensional chain affecting the critical dimension L2 of the chassis assembly: one located at the welded assembly of the front spring front support crossbeam, and the other at the crossbeam assembly in the stamped part. We need to perform a sensitivity analysis, selecting the closed loop of the dimensional chain that has a greater impact on critical dimension L2 for analysis. Here, we conduct an experimental simulation to study the influence of the welded assembly of the front spring front support crossbeam and the crossbeam assembly in the stamped part on the critical dimension L2 of the chassis. The test object is the currently produced 2800010-2051 chassis (including the welded assembly of the front spring front support crossbeam 2801090-84Q and the crossbeam assembly in the stamped part 2801110-2000). The test site is the matching operation room of the Process Experiment Center of the Technical Development Department. The test fixture is a flexible PCF fixture for the chassis, which serves for positioning and support. The testing equipment is a FARO articulated arm coordinate measuring machine. The experimental method involves simulating the width deviation of the welded assembly of the front spring front bracket crossbeam and a crossbeam assembly in the stamped parts by adding or removing shims. After assembling the frame assembly, the L2 dimension at the rear suspension mounting point of the cab is measured. When simulating the deviation of a particular crossbeam, the states of other parts remain unchanged. Here, we define a variable K to characterize the degree of influence of the change in crossbeam width deviation on the change in the L2 dimension of the frame, namely:

[0087]

[0088] ① Simulation of deviation in the welding assembly of the front spring and front bracket crossbeam

[0089] The deviations within the theoretical width ranges of "0", "±0.5", "±1", and "±1.5" were simulated by adjusting the shim thickness at the Y-axis mounting surface of the front spring front bracket crossbeam assembly and the right front spring bracket. The data is recorded in Table 2 below.

[0090] Table 2 Simulation Data Recording Table of Front Spring Front Bracket Crossbeam Welding Assembly Deviation

[0091]

[0092] The curve plot fitted based on the data records in Table 2 can be found in [the table]. Figure 2 As shown, it is easy to see that the slope Kfront of the front spring front support crossbeam is 0.24.

[0093] ② Simulation of deviation of crossbeam assembly during stamping

[0094] Because the stamped parts are currently freely assembled with a 1mm gap between the pin holes, the position and angle of the crossbeam connecting plate can vary within a certain range. Utilizing this structural characteristic, two extreme states of the connecting plate—"wider at the front and narrower at the back" and "narrower at the front and wider at the back"—were simulated, as well as a "parallel inward" state where the connecting plates on both sides tighten in the Y direction. During this test, the width of the front spring front bracket crossbeam welded assembly remained constant at "0". The data is recorded in Table 3 below. The curve fitted based on the data in Table 3 can be found in [the table / reference needed]. Figure 3 As shown, taking the minimum slope, it is easy to see that the slope K of the crossbeam assembly in the stamping process is 1.05.

[0095] Table 3. Simulation Data Recording Table of Deviation of Crossbeam Assembly in Stamping

[0096]

[0097] Based on the above crossbeam deviation simulation test, it is easy to see the sensitivity analysis results: K_stamped crossbeam assembly > K_front spring front bracket crossbeam. This indicates that the width deviation of the crossbeam assembly in the stamped part has a greater impact on the critical dimension L2 of the frame assembly than the welding summary of the front spring front bracket crossbeam. Therefore, the next step is to focus on the analysis and optimization of the closed loop of the dimension chain at the crossbeam assembly in the stamped part.

[0098] (2) Dimension chain analysis and tolerance allocation verification of the frame assembly at the middle crossbeam

[0099] ① Define dimensional accuracy requirements

[0100] After the chassis assembly is assembled, to ensure the pass rate of the critical dimension L2 of the chassis assembly, it is necessary to focus on controlling the accuracy of the outer width dimension of the chassis at the middle crossbeam. Currently, the design requirement for the outer width dimension of the chassis at the middle crossbeam assembly of the stamped parts is 800±2mm.

[0101] ② Dimensional chain analysis at the middle crossbeam

[0102] 800±2mm is the size that is naturally formed after the frame assembly is assembled, so it is a closed loop.

[0103] The design dimension A0 of the outer width of the crossbeam frame during stamping is influenced by the thicknesses of the left longitudinal beam sheet (A1), right longitudinal beam sheet (A2), left longitudinal beam inner reinforcing plate sheet (A3), right longitudinal beam inner reinforcing plate sheet (A4), left connecting plate dimension (A5), right connecting plate dimension (A6), stamped crossbeam dimension (A7), left pin floating at the bolt mounting holes of the crossbeam and connecting plate (A8), and right pin floating at the bolt mounting holes of the crossbeam and connecting plate (A9). The dimensional chain consists of 9 components, see [details omitted]. Figure 4 As shown.

[0104] ③ Check the tolerance of the closed loop

[0105] I. Determine the tolerances of each component ring by checking the tolerance standards and combining them with the actual manufacturing process level;

[0106] II. Calculate the tolerance of the closed loop based on the method of large number interchange (statistical method);

[0107] The tolerance of the frame outer width closed ring A0 at the middle crossbeam assembly calculated based on the large number interchange method is ±2.15mm, which does not meet the design tolerance requirement of ±2mm. Based on this actual tolerance, the pass rate of the critical dimension L2 of the frame assembly is 68.42%, which is far from meeting the requirement of 98%.

[0108] (3) Measures to improve the dimensional accuracy of the frame assembly at the middle crossbeam

[0109] Considering that the longitudinal beams, inner reinforcing plates of the longitudinal beams, crossbeams and crossbeam connecting plates of the frame are all thick plate stamping parts, the actual process is complex and the manufacturing precision of the parts is low. It is difficult to improve the corresponding sheet thickness tolerance, blanking punching tolerance, forming bending tolerance. Therefore, the dimensional accuracy of the frame assembly at the middle crossbeam is mainly improved by reducing the floating of the hole pins and reducing the number of component rings.

[0110] I. Reduce pin float and decrease frame outer width closed-loop tolerance:

[0111] Without altering the structure, non-standard rivets (φ14.9 diameter with φ15 holes) are used at the connection between the crossbeams and the crossbeam connecting plates to reduce the floating of the hole pins. The non-standard rivets are installed diagonally, for a total of 8.

[0112] The floating tolerance of the pin holes using non-standard rivets was reduced from ±1mm to ±0.2mm, and the tolerance of the outer width closed ring A0 of the frame was reduced from ±2.15mm to ±1.65mm, meeting the design tolerance requirements.

[0113] For the critical dimension L2 of the existing production frame assembly after using non-standard rivets, the pass rate was 85%, an improvement from 68.42%, but still below the target requirement of 98%. Considering that the middle crossbeam assembly consists of thick plate stamping parts, on the one hand, the manufacturing precision stability is poor, and on the other hand, deformation will occur during assembly with the longitudinal beams and the internal reinforcing plates of the longitudinal beams. Therefore, it is very difficult to further improve the dimensional accuracy. Thus, further structural optimization is needed to achieve the dimensional accuracy target.

[0114] II. Reduce the number of component rings to decrease the tolerance of the closed ring of the frame outer width.

[0115] The structure of the central crossbeam was optimized by integrating six parts into one part (integrated casting structure) through integrated design.

[0116] For the optimized one-piece casting, a new dimensional chain analysis was performed on the beam structure, such as... Figure 5 As shown, there are a total of 5 constituent rings.

[0117] Determine the tolerances of each component ring by checking the tolerance standards and combining them with the actual manufacturing process level;

[0118] The closed-loop tolerance was calculated using the large number interchange method, reducing the outer width closed-loop tolerance A0 of the frame to ±0.7mm, which meets the design tolerance requirements. For the currently produced frame using a cast single-beam structure, the critical dimension L2 of the frame assembly was inspected, and the pass rate was 100%, meeting the dimensional accuracy target requirements, proving the feasibility of this dimensional accuracy optimization measure.

[0119] Improvement Summary: Through comparative analysis of actual results, we completed the improvement of drawings and accumulated experience in the design of dimensional tolerances for the chassis assembly.

[0120] Example 3:

[0121] The present invention also provides an electronic device, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; the memory is used to store computer programs; and the processor is used to implement the frame assembly dimensional tolerance design method when executing the program stored in the memory.

[0122] Example 4:

[0123] The present invention also provides a storage medium having a computer program stored thereon, which is executed by a processor to implement the aforementioned chassis assembly dimensional tolerance design method.

[0124] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for designing dimensional tolerances for a vehicle frame assembly, characterized by the following steps: include: S1. Size problem identification: Decouple size problems that affect vehicle installation and quality, identify key vehicle dimensions related to quality problems, and identify key dimensions of the chassis assembly from the identified key vehicle dimensions; S2. Chassis assembly dimensional accuracy design optimization: Identify the current status of the critical dimension accuracy of the chassis assembly, set the critical dimension accuracy target for the chassis assembly, and analyze and optimize the critical dimensions of the chassis assembly to achieve the accuracy target; S3. Complete the improvements and summarize.

2. The frame assembly dimensional tolerance design method according to claim 1, characterized in that, Step S1 includes: S11. Based on the DFMEA complex problem analysis approach, identify vehicle installation and quality issues and analyze the parts related to the vehicle's critical dimension chain; S12. Identify and list all critical dimensions of the vehicle that are relevant to installation and quality issues; S13. Based on the listed key dimensions of the whole vehicle, identify the key dimensions of the chassis assembly and classify them into two categories: Category A and Category B. Category A consists of key dimensions that need further decomposition, while Category B consists of key dimensions that do not need further decomposition.

3. The frame assembly dimensional tolerance design method according to claim 1, characterized in that, Step S2 includes: S21. Identification of the current status of critical dimension accuracy of the chassis assembly: Based on the measurement of the critical dimension data of the chassis assembly of the current production model, the data is then compared with the theoretical dimensions to obtain the current status of the dimension qualification rate; S22. Target setting for critical dimensions of the chassis assembly: Set target for the pass rate of critical dimensions of the chassis based on standards, regulations, experience, or benchmarking. S23. Achievement of critical dimension accuracy targets for chassis assembly: Define the closed loop of the dimension chain, and analyze the achievement paths for Class A and Class B critical dimension accuracy based on experience and benchmarking methods.

4. The frame assembly dimensional tolerance design method according to claim 3, characterized in that, In step S21, the identification of the current accuracy status of key dimensions of the chassis assembly includes: S2111. Based on actual measurements, derive the key dimensions of the Class A frame assembly of interest; S2112. Confirmation of theoretical tolerances for critical dimensions of chassis assembly: Based on benchmarking results, project inputs and vehicle manufacturing and assembly requirements, confirm the theoretical tolerance values ​​for critical dimensions of Class A chassis assembly. S2113, Statistical Analysis of Critical Dimension Pass Rate of Chassis Assembly: Based on the chassis of currently produced models, the actual measurement of critical dimensions of Class A chassis assemblies is conducted to obtain all measured values. The difference between the measured values ​​and the benchmark values ​​is used to obtain the actual tolerance. The actual tolerance is then compared with the theoretical tolerance to determine the number of data that meet the theoretical tolerance. This is achieved through a formula... The pass rate is calculated.

5. The frame assembly dimensional tolerance design method according to claim 3, characterized in that, In step S22, the specific method for setting the target for the pass rate of key dimensions of the chassis by benchmarking is to measure the key dimensions of the chassis of internationally advanced commercial vehicle companies, find the gaps by benchmarking, and set the target for the pass rate of key dimensions of the chassis.

6. The frame assembly dimensional tolerance design method according to claim 3, characterized in that, In step S23, the path to achieving the accuracy of critical dimensions for category A includes: S2311. Identify the closed loop of the dimensional chain that has a significant impact on the critical dimensions of the chassis assembly: By performing loop sensitivity analysis on the dimensional chain, select the closed loop of the dimensional chain that has a significant impact on the critical dimensions based on the sensitivity analysis results; S2312, Dimensional Chain Analysis and Tolerance Allocation Verification of Chassis Assembly: Clarify the accuracy requirements of the selected dimensional chain closing loop, analyze the component loops of the dimensional chain, and verify the tolerance of the closing loop; S2313, Measures to improve the dimensional accuracy of the frame assembly: Considering the reduction of component rings, reasonable dimension marking, process implementation capability, and hole pin floating methods, the tolerance optimization is carried out by comprehensively considering cost control and process stability during the process of achieving the tolerance of component rings, and the 3DCS dimensional engineering software is used for verification and analysis.

7. The frame assembly dimensional tolerance design method according to claim 3, characterized in that, In step S23, the path to achieve the critical dimension accuracy of category B is based on the measures to achieve dimension accuracy and complete experimental verification, including benchmark standardization, improvement of part dimension accuracy, improvement of process tooling applicability, and maintenance of dimension accuracy.

8. The frame assembly dimensional tolerance design method according to claim 1, characterized in that, In step S3, a comparative analysis of actual results is conducted to complete the drawing improvement and accumulate design knowledge on the dimensional tolerances of the chassis assembly.

9. An electronic device, characterized in that, It includes a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; the memory is used to store computer programs; and the processor, when executing the program stored in the memory, implements the frame assembly dimensional tolerance design method as described in any one of claims 1-8.

10. A storage medium having a computer program stored thereon, characterized in that, The program is executed by the processor to implement the chassis assembly dimensional tolerance design method as described in any one of claims 1-8.

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