在投影仪上,用放大图比较法测量中、小尺寸零件圆弧半径,当放大图与被测件投影放大的影像半径不相等时,在两者贴合比较时,两圆弧不重合,出现缝隙f(如图2、3示)。如能用投影仪读数机构测得f值,并在放大图量出与f相对应的弧弦长L(图1、2)由已知放大图半径(R)计算出相应的中心角 In the projector, with the enlargement comparison method to measure the small and medium-sized parts arc radius, when the enlarged image and the measured projection enlarge the image radius is not equal, when the two fit comparison, the two arcs do not coincide, Appear gap f (Figure 2,3). If you can use the projector readings measured f-value, and in the enlarged view and f corresponding to the chord length L (Figure 1,2) from the known magnification radius (R) to calculate the corresponding center angle