Car body process clamping point strength analysis method

Abstract

The invention discloses a vehicle body process clamping point strength analysis method. Finite element working conditions for strength simulation analysis of a vehicle body clamping point structure on a coating and final assembly line are created, and analysis and evaluation are executed. Specifically, firstly, a basic framework of a vehicle body finite element mesh model of the coating and final assembly process is formed, clamping points are set on the basic framework and restrained, and then different attitude angles of a white vehicle body in an electrophoresis cell are simulated to load a load reflecting the actual dynamic stress condition of the vehicle body. Loading is carried out in combination with the bearing stress condition of a complete vehicle body on the final assembly line; and finally, outputting a simulation result according to the created load step by utilizing the configured vehicle body finite element mesh model, so as to determine whether the clamping point meets a preset strength target or not. According to the method, the strength performance of the clamping point of the vehicle body is comprehensively, objectively and practically analyzed and investigated, the problems of inaccuracy, insufficiency and the like caused by an existing analysis scheme are avoided, and therefore the performance index of the clamping point can be rapidly, effectively and accurately evaluated.

Description

Technical Field

[0001] The invention relates to the field of automobile manufacturing, and in particular to a method for analyzing the strength of clamping points in a vehicle body process. Background Art

[0002] Strength refers to the ability of a material to resist plastic deformation and fracture under the action of external forces. The vehicle body serves as the installation carrier for many functional parts. In addition to arranging the installation points of various components, a number of process clamping point structures will be designed on the local part of the vehicle body. During the vehicle production process, they serve as the bearing points for production processes such as transportation and flipping. If the strength of the process clamping points is insufficient, it will have a great impact on the quality of the entire vehicle.

[0003] There are many limitations in the strength analysis of traditional process clamping points. On the one hand, the painting line analyzes the state of the car body entering and exiting the electric pool, and counterweights the opening and closing parts by constraining the painting hanging points of the car body. It is divided into only three working conditions: the car body is horizontal, the car body is tilted up and down 30 degrees respectively, and 1.2 times the acceleration of gravity is applied; on the other hand, the general assembly line only intercepts part of the car body finite element model, constrains the cross-section position, and sets the load to 1.1 times the curb mass according to experience, and then analyzes the front and rear hanging points one by one according to the front and rear axle load ratio. Summary of the invention

[0004] In view of the above, the present invention aims to provide a method for analyzing the strength of clamping points in vehicle body processes to solve the above-mentioned technical problems.

[0005] The technical solution adopted by the present invention is as follows:

[0006] The present invention provides a method for analyzing the strength of a vehicle body process clamping point, which includes:

[0007] Form the basic framework of the car body finite element mesh model for the painting process and the final assembly process;

[0008] The clamping points are processed on the basic structure and constrained; wherein a plurality of skid holes of the vehicle body are used as clamping points for the painting process, and the established lifting points on the complete vehicle body are used as clamping points for the assembly process;

[0009] According to the actual clamping operation conditions, the load applied to the clamping point is determined and the load step is created to obtain the configured body finite element mesh model; when the load is applied to the clamping point of the painting process, the body posture angle change of the body in the electrothermal tank is simulated;

[0010] Perform computational analysis using the configured vehicle body finite element mesh model;

[0011] The maximum value of the model output result is read, and combined with the established strength evaluation index, it is determined whether the clamping point meets the preset target.

[0012] In at least one possible implementation, when forming the basic architecture, a vehicle body finite element mesh model of the final assembly process is set to be consistent with a total weight of the vehicle in the heaviest state established in the final assembly process.

[0013] In at least one possible implementation, the performing the clamping point processing includes:

[0014] Obtain a first rigid unit from the inner plate and the outer plate of the skid hole, wherein the main node of the first rigid unit is set as the center of the skid hole;

[0015] The second rigid unit is obtained according to the size of the contact area at the lifting point, wherein the main node of the second rigid unit is set to the center of the contact area of ​​the lifting point.

[0016] In at least one possible implementation manner, constraining the clamping point includes: constraining the degree of freedom of the clamping point based on an actual contact area between the clamping tool and the vehicle body.

[0017] In at least one possible implementation, the method of applying a load to the clamping point includes:

[0018] For the finite element mesh model of the car body in the painting process, a gravity field with loads superimposed in the X and Z directions is applied;

[0019] For the car body finite element mesh model of the final assembly process, a gravity field with a load in the downward Z direction is applied.

[0020] In at least one possible implementation, the performing of the computational analysis includes: if it is determined that the displacement or movement of the loading point is abnormal, the configured vehicle body finite element mesh model is corrected again until the computational analysis result is correct.

[0021] Compared with the prior art, the main design concept of the present invention is to create finite element working conditions for strength simulation analysis of the clamping point structure of the vehicle body on the painting and assembly lines, and perform analysis and evaluation. Specifically, the basic framework of the vehicle body finite element mesh model of the painting process and the assembly process is first formed, and the clamping points are set and constrained thereon. Then, the different body posture angles of the body in the electrothermal pool are simulated, and the load that can reflect the actual dynamic stress condition of the vehicle body is loaded, and the load is loaded in combination with the stress condition of the complete vehicle body on the assembly line; then the configured vehicle body finite element mesh model is used to output according to the created load step, and finally, combined with the established strength evaluation index, it is determined whether the clamping point meets the preset target. The present invention conducts a comprehensive, objective and practical analysis and investigation on the strength performance of the vehicle body clamping point, avoiding the problems of inaccurate and incomplete results caused by the existing analysis scheme, so that the clamping point performance index can be quickly, effectively and accurately evaluated. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described below with reference to the accompanying drawings, in which:

[0023] Figure 1 A schematic diagram of a method for analyzing the strength of clamping points in a vehicle body process provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention.

[0025] After analyzing the existing strength analysis ideas for the clamping point structure of the body process, the present invention believes that there are at least the following defects:

[0026] (1) The analysis of the painting line only focuses on the stress conditions of the vehicle body in three states, and the dynamic stress of the vehicle body in the electrothermal tank is missing.

[0027] (2) The analysis of the final assembly line is not consistent with the actual situation because it is based on a partial model and cannot examine the stress state of the entire vehicle body.

[0028] (3) The load applied in the process clamping point strength analysis is an empirical value and is not extracted based on the actual stress conditions, which will cause the results to deviate from the actual situation.

[0029] In view of this, the present invention proposes an embodiment of a method for analyzing the strength of a clamping point in a vehicle body process. Specifically, Figure 1 shown, including:

[0030] Step S1, forming a basic framework of a vehicle body finite element mesh model;

[0031] Specifically for the painting line, a finite element mesh model can be established based on the body-in-white 3D CAD model. In actual operation, the model mainly includes: all sheet metal parts (i.e. BIW+white door+fender), and can be set as: material plasticity and no contact.

[0032] Specifically for the painting line, a finite element mesh model can be established based on the three-dimensional CAD model of the vehicle body. In actual operation, the model mainly includes: TB vehicle body + chassis counterweight + two people (i.e., the weight of one person is configured on the left and right seats in the front row), and can be set as: material plasticity, no contact. It can be emphasized here that it is preferred to make the model consistent with the total weight of the vehicle in the heaviest state in the established process of the general assembly line.

[0033] Step S2, performing clamping point processing on the infrastructure; wherein a plurality of skid holes on the vehicle body are used as clamping points for the painting process, and a predetermined lifting point on the complete vehicle body is used as a clamping point for the assembly process;

[0034] Specifically for the painting line, several skid holes on the car body can be used as clamping points for the painting process, and washers (a type of unit in finite element analysis, which constructs several layers of relatively regular quadrilateral grids with a ring structure around the hole) are established at the inner and outer panels. The two circles of washer nodes on the inner and outer panels are captured as an rbe2 rigid unit (a rigid connection unit in finite element analysis, mainly used to rigidly connect multiple slave nodes to a main node) to complete the constraint point processing, where the main node of the rbe2 rigid unit can be set to the center of the skid hole.

[0035] Specifically for the final assembly line, the lifting points on the complete vehicle body can be determined as the clamping points of the final assembly process according to the process requirements of the final assembly line, and the rbe2 rigid unit can be grabbed according to the size of the contact area at the lifting point to complete the constraint point processing, where the main node of the rbe2 rigid unit can be set to the center of the lifting contact area.

[0036] Step S3, constraining the clamping point;

[0037] Specifically for the painting line, the freedom of the main nodes of the rbe2 rigid units at several skid holes is constrained. The clamping points of the painting process of a specific vehicle model can be constrained according to actual conditions. However, it should be emphasized that when constraining the freedom of the clamping points, the contact area between the clamping tooling and the vehicle body needs to be considered.

[0038] Specifically for the final assembly line, the degrees of freedom of the main nodes of the rbe2 rigid unit at several lifting points are constrained. Similarly, the clamping points of the final assembly process of a specific vehicle model can be constrained according to actual conditions.

[0039] Step S4, according to the working conditions of the actual clamping operation, determine the load applied to the clamping point and create a load step to obtain a configured body finite element mesh model; wherein, when the load is applied to the clamping point of the painting process, the body posture angle change of the body in the electrothermal tank is simulated;

[0040] Regarding the implementation details of loading, for the painting line, the load applied is a gravity field superimposed in the X and Z directions to simulate the body posture angle change of the body in the electrothermal tank. Specifically, the load expression can be referred to as: Fx=1.5G*sinwt, Fz=1.5G*coswt, where G is the body gravity of the painting process under the 1g gravity field of the analysis model, w=6.283, that is, the load change frequency is 1Hz, and t is the operation time; for the general assembly line, similarly, a load of -1G gravity field in the Z direction can be applied.

[0041] Regarding the implementation details of creating load steps, specifically for the clamping points of the coating process, you can set the static solution and load step, and at the same time, apply Fz (0., 0., 1. represents a 1G gravity field in the z direction) and Fx (1., 0., 0. represents a 1G gravity field in the x direction) as described above. The time interval for outputting the results can be set to 0.05s, and U (displacement) and PEEQ (plastic strain) are output accordingly; specifically for the clamping points of the assembly process, you can set the static solution and load step, and at the same time, apply a 1G gravity field downward in the z direction as described above, and the time interval for outputting the results can be set to 0.1s, and U (displacement) and S (stress) are output accordingly.

[0042] Step S5, performing calculation and analysis using the configured vehicle body finite element mesh model;

[0043] The finite element model established above can be saved as an *.INP file and submitted to Abaqus software for calculation. In the analysis process, HyperView is preferably used to check whether the displacement and animation of each loading point are continuous and reasonable. If they are correct, the next step can be executed; if the calculation and analysis determine that the loading point displacement or movement is abnormal, the configured body finite element mesh model is corrected until the calculation and analysis results are correct, and then the next step is executed:

[0044] Step S6: read the maximum value of the model output result, and determine whether the clamping point meets the preset target in combination with the established evaluation index.

[0045] It can be understood that for the painting line, the output result read is the maximum plastic strain PEEQ in all load steps; for the assembly line, the output result read is the maximum stress S in the last load step.

[0046] In summary, the main design concept of the present invention is to create finite element working conditions for strength simulation analysis of the clamping point structure of the vehicle body on the painting and assembly lines, and perform analysis and evaluation. Specifically, the basic framework of the vehicle body finite element mesh model of the painting process and the assembly process is first formed, and the clamping points are set and constrained thereon, and then the different body posture angles of the white body in the electrothermal pool are simulated, and the load that can reflect the actual dynamic stress condition of the vehicle body is loaded, and the load is loaded in combination with the stress condition of the complete vehicle body on the assembly line; then the configured vehicle body finite element mesh model is used to output according to the created load step, and finally combined with the established strength evaluation index, it is determined whether the clamping point meets the preset target. The present invention conducts a comprehensive, objective and practical analysis and investigation on the strength performance of the vehicle body clamping point, avoiding the problems of inaccurate and incomplete results caused by existing analysis schemes, so that the clamping point performance indicators can be quickly, effectively and accurately evaluated.

[0047] If the expressions expressing orientation are mentioned in the embodiments of the present invention, they are relative concepts based on the embodiments. In addition, "at least one" means one or more, and "plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent the existence of A alone, the existence of A and B at the same time, and the existence of B alone. Among them, A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following" and similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b and c can be represented by: a, b, c, a and b, a and c, b and c, or a and b and c, wherein a, b, c can be single or multiple.

[0048] The above describes in detail the structure, features and effects of the present invention based on the embodiments shown in the drawings, but the above is only a preferred embodiment of the present invention. It should be noted that the technical features involved in the above embodiments and their preferred methods can be reasonably combined and matched into a variety of equivalent schemes by those skilled in the art without departing from or changing the design ideas and technical effects of the present invention; therefore, the present invention is not limited to the scope of implementation shown in the drawings, and all changes made in accordance with the concept of the present invention, or modifications to equivalent embodiments with equivalent changes, which still do not exceed the spirit covered by the specification and drawings, should be within the protection scope of the present invention.

Claims

1. A method for analyzing the strength of clamping points in vehicle body processes, characterized in that: include: Form the basic framework of the car body finite element mesh model for the painting process and the final assembly process; The clamping points are processed on the basic structure and constrained; wherein a plurality of skid holes of the vehicle body are used as clamping points for the painting process, and the established lifting points on the complete vehicle body are used as clamping points for the assembly process; According to the actual clamping operation conditions, the load applied to the clamping point is determined and the load step is created to obtain the configured body finite element mesh model; when the load is applied to the clamping point of the painting process, the body posture angle change of the body in the electrothermal tank is simulated; Perform computational analysis using the configured vehicle body finite element mesh model; The maximum value of the model output result is read, and combined with the established strength evaluation index, it is determined whether the clamping point meets the preset target.

2. The method for analyzing the strength of the clamping point of the vehicle body process according to claim 1 is characterized in that: When forming the basic framework, the vehicle body finite element mesh model of the final assembly process is set to be consistent with the total weight of the vehicle in the heaviest state established in the final assembly process.

3. The method for analyzing the strength of the clamping point of the vehicle body process according to claim 1, characterized in that: The clamping point processing comprises: Obtain a first rigid unit from the inner plate and the outer plate of the skid hole, wherein the main node of the first rigid unit is set as the center of the skid hole; The second rigid unit is obtained according to the size of the contact area at the lifting point, wherein the main node of the second rigid unit is set to the center of the contact area of ​​the lifting point.

4. The method for analyzing the strength of clamping points in vehicle body processes according to claim 1, characterized in that: The constraining the clamping point includes: constraining the degree of freedom of the clamping point based on the actual contact area between the clamping tool and the vehicle body.

5. The method for analyzing the strength of clamping points in vehicle body processes according to claim 1, characterized in that: Ways to apply loads to the clamping point include: For the finite element mesh model of the car body in the painting process, a gravity field with loads superimposed in the X and Z directions is applied; For the car body finite element mesh model of the final assembly process, a gravity field with a load in the downward Z direction is applied.

6. The method for analyzing the strength of the clamping point of the vehicle body process according to any one of claims 1 to 5, characterized in that: The calculation and analysis comprises: if it is determined that the displacement or movement of the loading point is abnormal, the configured vehicle body finite element mesh model is corrected again until the calculation and analysis result is correct.

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