Abstract: Four-wheel alignment is a significant parameter to ensure that the vehicle has good driving performance. Testing and adjusting it effectively has important implications for improving the safety and economy of vehicles. This paper mainly analyzes the parameters of rear axle toe-in in the four-wheel alignment. In this paper, the parameters of rear axle toe-in were adjusted at the supplier first, then were tested at the vehicle factory. Due to the high adjustment rate of the rear wheel toe-in in the factory, the workload of the workers is greatly increased. This paper used 6 Sigma method to solve the actual issues of rear wheel toe-in. Through checking and analyzing the process from supplier to vehicle factory, and a series of definition, measurement, analysis, improvement and control, the several parameters causing problems were found out step by step. After improving and controlling the parameters, the adjustment rate of rear wheel toe-in was reduced, and the problem of low efficiency caused by similar reasons was reduced in the future.

Key words: Four wheel alignment; Rear axle toe-in; Tolerance adjustment; 6 Sigma

摘要： 四轮定位是确保车辆具有良好行驶性能的重要参数，对其有效地进行检测和调整，对 提高汽车的安全性和经济性有重要意义。论文主要针对四轮定位中后轮前束参数进行分析， 文中后轮前束参数会先在供应商处调整好，之后在工厂整车下线时再对其参数进行检测。由 于发现工厂后轮前束调整率高，导致生产人员工作量大增。因此，利用 6 Sigma 方法，从供 应商到整车离线的过程进行排查和分析，通过定义、测量、分析、改进和控制六个步骤逐步 找出引起问题的几个过程参数，并对其进行改善和控制，最终达到降低后轮前束调整率的目 的，并且可减少日后由于相似原因造成效率低等问题。

关键词: 四轮定位；后轮前束；公差调整；6 Sigma