【作者】 李强；

【导师】 余忠华；

【作者基本信息】 浙江大学 ， 工程管理（专业学位）， 2023， 硕士

【摘要】 现今,在全球大力发展新能源汽车的时代背景下,传统汽车制造企业纷纷进行战略转型。在转型过程中如何提升新产品的市场竞争力,优先抢占市场资源,以实现风险转化为机遇,是每一家传统汽车制造企业当前最为密切关注的问题。质量作为企业市场竞争力的重要因素,通过质量提升来降低成本,提高顾客满意,无疑是最行之有效的方法之一。本次论文研究主要通过六西格玛DMAIC的方法来提升D公司电动汽车电机转轴加工过程的产品合格率,并降低质量损失成本。在定义阶段通过SIPOC流程图展开并结合质量损失成本分析,明确了磨削过程圆度不合格、挤压花键跳动不合格和激光焊接裂缝三个待改进的质量问题。在磨削圆度不合格问题的测量和分析阶段,通过因果分析、因果矩阵分析以及全析因试验分析找到修砂轮周期和精磨进给两个关键影响因素并确定了交互效应;改进阶段通过单纯形法对关键影响因素进行优化;控制阶段对影响因素建立了过程管理控制。在花键跳动不合格问题的测量和分析阶段,通过故障树分析确定了挤压前底孔跳动大的关键影响因素,进一步通过5问分析法确定了左侧精车工序过程设计不合理的根本原因;通过散布图优化方法确定精车工序底孔跳动控制值并对车削过程进行了参数优化;在控制阶段设立了均值-极差控制图对底孔跳动进行统计过程控制。在激光焊接裂缝问题的测量和分析阶段,通过5问分析法找到了在换型过程中激光探头位置调整不正确的直接原因,和现场员工培训管理过程不完善的根本原因;通过引进工作指导四阶段法对一线班组长和员工培训过程进行优化;控制阶段使用技能矩阵图对根本原因进行控制,并对换型过程探头调整位置设定可视化控制要求。最终通过本次六西格玛质量提升项目的实施将电机转轴的合格率提升到了95.53%,可以为D公司节约275.2万元每年的预期经济效益,也提升了电机转轴产品的市场竞争力,对公司的发展意义重大。更多还原

【Abstract】 Nowadays,under the background of new energy vehicles vigorous development in the world,traditional automobile manufacturing enterprises are conducting strategic transformation.Based on the situation,improve the competitiveness of products,as earlier as seizing market,and realize the risks into opportunities are the most significant concerned issues for every traditional automobile manufacturing enterprise.As an key factor of enterprise’s competitiveness,undoubtedly quality improvement is one of the most effective methods to reduce costs and improve customer satisfaction.This thesis is focus on improving the machining process qualification rate of rotor shaft in D Company,aiming to reduce the quality cost via DMAIC method.In the define stage,identified the problem of low qualification rate of the machining process by SIPOC tool and scraping cost data statistics analysis,three major problems are detected: roundness in OP70,spline runout in OP60 and cracks in OP30.In the problem solving of OP70,the two key factors and interaction effect of wheel dressing cycle and precision feed rate are determined by causal matrix analysis and DOE;the key factors were optimized by graphic of simplex algorithm in improve stage;quality control is established for the influencing factors in control stage.In the problem solving of OP60,the key influencing factors of inner hole runout before pressing are determined through FTA,the key factor is determined and optimized;the control chart is installed to control the inner hole runout before pressing.In the problem solving of OP30,the root cause is detected by 5why analysis;the training process of front-line team leaders and employees was optimized by the four stage method of work guidance in improve stage;finally the root cause is controlled by using the employee skill matrix chart,and visualized control requirements are set for the probe adjustment position during the switch process.Through the implementation of quality improvement based on DMAIC method,the qualification rate of rotor shaft has been increased to 95.53%,which can save 2.752 million yuan as expected for D company each year.Meanwhile improved the competitiveness of this product,which has great significance for development of the D company as long-term.更多还原