Application of tolerance analysis of Mpale in automotive chassis suspension system

The role of the chassis is to accept the power of the engine, so that the wheel rotates, and to ensure that the car according to the driver's control normal driving. The chassis includes the four parts of the drive system, the driving system, the steering system and the braking system, usually referred to as the driveline, drive train, steering and braking systems. The suspension is the general term of the transfer force connection between the frame and the axle, and its function is to transfer the supporting force, traction, braking force and lateral force of the road to the wheel and the torque caused by these forces to the frame (or body) to ensure the normal driving of the car. In the entire chassis suspension system, it is necessary to consider the front and outside inclination parameters, and in the tolerance modeling process, they are used as the analysis object, and the influence of each input tolerance on the analysis object is calculated.

I. Tolerance modeling process

In the three-dimensional CAD software CATIA completed modeling, open integrated in CATIA environment Cetol tolerance analysis software module, simulation of the real-state model of the Assembly process. The entire assembly is equipped with a car body as the base of the assembly, the Assembly sequence satisfies: first body-subframe-hem arm; then subframe-steering, body-damper (divided into two parts), final steering knuckle-hem arm, damper, steering machine assembly.

Two. Create assembly constraint relationships and related dimensional tolerances between parts.

Setting the assembly constraint relationship between the knuckle and the hem arm requires limiting translational degrees of freedom in the X, Y, Z directions, releasing the rotational degrees of freedom along the X, y, and z directions. The Cetol simulates the assembly constraint relationship between parts based on the actual assembly constraint state between the components.

Three. Analysis results

Enter the relevant dimensional tolerances and geometric tolerances of each part drawing, assuming that all part sizes in the processing process to meet the processing capacity cpk=1, each input size to meet the normal distribution, the passing rate of the Left front bundle is 39.35%, the Sigma value is 0.52, the value is too low, does not meet the requirements. According to the same hypothesis, the statistical distribution of the left angle is obtained, as shown in the right image, and its quality qualified rate is 100%,sigma value of 6.41.

Four. Summary

This analysis only evaluates the assembly pass rate for the left Front toe and the outside inclination of the front-Front camber of the assembly, as the entire front suspension is symmetrical, and the right front and inclination are no longer calculated. The results are obtained by analysis: The front beam left Front toe is less than 3sigma, and the external tilt-Front Camber achieves 6sigma design requirements. The results of the analysis show the ranking of the contribution of the front beam and the camber, and the location of the specific size is pointed out. The sensitivity numerical sort provides the direction for the design dimension adjustment. (More clicks:Maple)

Application of tolerance analysis of Mpale in automotive chassis suspension system