Assembly Accuracy Control And Optimization Of Front-body For Better Assembly Quality Of Front Suspension

The driving stability,ride comfort and safety are main aspects of car performance the study of vehicle driving performance focus on auto-body and chassis respectively.The front-body is an important part of auto-body.The assembly deviation analysis of front-body is usually as part of the auto-body,so as to make sure the shape accuracy of auto-body.But at the same time,deviations of matching points between the front-body and the front suspension will have significant influence on the alignment parameters of front wheel,and to move forward a single step affects the driving performance.Therefore,establish the relationship between the front body and the suspension,analyse the assembly deviation of matching points in the front-body,and improve the accuracy of the matching points of front suspension are key to stabilize the front wheel alignment parameters and ensure driving performance of vehicle.Based on the front suspension system,this paper creates the assembly model of the suspension structure by using Adams;Analysis the influence that the matching points have on the alignment parameters.And find out the most sensitive deviation direction by orthogonal experiment..Finally,determine the position accuracy requirement of matching points on front auto-body.Secondly,this paper analyzes the welding assembly process of the front body.Using the deviation analysis software 3DCS to analysis the causes of the maching points deviation.At the same time,this paper will verify the simulation analysis results bythe three-coordinate measurement datas.Finally,it will analyze the influence that the different assembly order have on the assembly deviation and determine the optimal assembly order.On this basis,optimizing parts tolerances according to the requirements of front suspensionThe main research of this paper as follows is:(1)Analysis the influence of matching points on positioning parameters.First of all,this paper introduces the importance of the front wheel alignment parameters to car performence.Then,it establishes the kinematic simulation model of the front suspension by using ADAMS,analyze the sensitivity of the matching points to alignment parameters,study the influence order of different deviation directions.Finally,determine the position accuracy requirement of the matching points between front suspension and car body.(2)The assembly process and quality evauation of fron-bodyThis chapter introduces the structure of the front-body,the assembly process and the method of quality evaluation.Firstly,it introduces the structure,functions,and the positioning information of the front-body and assembly process,such as the assembling sequence of the parts in detail.Then,it points out the control target and the assembly quality evaluation method of the front-body.This chapeter is the basis of the 3DCS assembly variation analysis model.The assembly deviation analysis and optimization of front-body(3)The assembly deviation analyzition and optimization of front-bodyThis chapter focus onestablishing the assembly model and optimizing assembly sequence and part tolerance Firstly,it introduces the process of building the 3DCS model and then simulates the assembly of the front body based on the assembly process.it analyze the assembly deveation of the matching points And the relationship of contribution among the vieration of parts,deviation of fixtures and matching points.At the same time,it will verify the simulation analysis sresults by using the three-coordinate measurement datas in the body-welding shop.Based on this,the chapter will analyze the influence of different assembly order on the assembly deviation of the hard points and determine the optimal one.Finaly,optimize the tolerances of hard points according to the requirements of suspension alignment parameters.