Development of Automatic Inside Diameter Gauge for Arm Vane

An automatic inside diameter gauge for arm vane has been developed. Arm vane is an important constituent part of a variable vane assembly that adjusts quantity of turbo-charger exhaust flowing. A hole is machined at the edge of the arm. It is necessary to manage the size of the hole strictly. In the gauge, two optical systems are used to measure the diameter of the hole from upper and lower sides. Diameter of a maximum inscribed and minimum circumscribed circle are calculated by an image processing to judge the quality of the hole. Part is inspected in 1.8 seconds with ±5 μm of repetition accuracy. Result of a performance test was 100 % detection of defective parts with 5 % over detection of good parts. Details are described in this article.