相邻金属孔间壁厚现场检测系统关键技术的研究

Study on Key Technique of Field Inspection System of Wall Thickness Between Adjacent Metal Holes

相邻金属孔间的壁厚测量以往都是根据镗床加工过程中的进刀量计算得出 ,精度较低。本文提出了一种应用电容传感器对两个金属孔间壁厚在线检测的系统。基于电容传感器 ,研究了电容测头的电场边缘效应的影响及保护环的宽度选择 ,设计了测量孔壁的电容测厚传感器进行差动测量。系统由两个距离确定的电容差动测厚传感器、测量电路、A/D接口及软件组成的。对壁厚 2mm ,孔径 3mm的相邻金属孔壁厚的测量实验显示 ,误差达到 0 .3μm。系统属于非接触测量 ,无需修正测头及工件变形误差。此系统测量精度高 ,测量速度快 ,操作方便 ,全套仪器便携 ,是解决相关壁厚现场精密检测问题的好方法。

The measurement of wall thickness between adjacent metal holes was anciently calculated by the amount of feed, whose accuracy was very low. A field inspection system of wall thickness of two adjacent metal holes with capacitance sensors is presented. Based on the capacitance type sensor, the influence of edge effect of gauge head and the width of protecting ring are studied, two thickness-measuring capacitance sensors are introduced to measure differentially the wall thickness between two holes. The system is composed of two differential thickness capacitance sensors, the distance between gauge heads of which is determinate, measuring circuit, A/D interface and software. In laboratory experiment, the measuring error of the metal workpiece, in which there are two 3 mm adjacent holes with 2 mm wall thickness between them, is 0.3 micron. In addition, being non-contact measurement, the system dispenses with distortion error compensations of gauge head or workpiece. The system is portable, easy to manipulate, and has high measurement accuracy and fast response.