基于瑞利分布的SPC控制图应用研究

该文通过分析生产过程中印刷电路板（PCB）上元件位置偏移形成的原因，建立了元件位置偏移的数学模型，进而论证了元件位置偏移距离服从瑞利分布。由于休哈特x控制图要求所控制的质量属性服从正态分布，用其控制PCB元件位置偏移会出现误判。该文对它进行了优化改进，提出了更适合于控制元件位置偏移距离的瑞利控制图，实验结果表明瑞利控制图具有更好的效果。另外，该文也提出了一种利用数据库来构造专家系统的方法，采用该方法的控制图自动模式识别效率比一般的专家系统有所提高，这种新的思路对控制图模式的智能识别将有所帮助。

SPC Control Chart Based on Rayleigh Distribution

This paper makes a mathematical model of position displacement of components on PCB, after analyzing the causes that result in position displacement of components. Then it is proved that position displacement of components follows Rayleigh distribution. Because Shewhart X chart requires that the quality character data should follow the normal distribution, wrong conclusions will be gotten, if X chart is used to control the position displacement of components. Rayleigh chart is proposed to control the position displacement of components, which is gotten by optimized X chart. Experimental result shows that Rayleigh chart can meet the producing requirements. The paper also proposes a method for achieving an expert system by using database. It is more efficient to recognize control chart pattern than the popular expert system. The technology used in the expert system is worth spreading.