Semi-arc detection device

The invention relates to a semi-arc detection device. The semi-arc detection device comprises a semi-arc body, wherein a straight bar-shaped handle is arranged on a concave side of the semi-arc body; three positioning ends, namely a first positioning end, a second positioning end and a third positioning end are arranged on the semi-arc body; inspection blocks are arranged on the first positioning end and the second positioning end; bushing holes and screw holes are formed in the third positioning end; and a dial gauge is connected with the inner side of one bushing hole through a sharp-end inspection rod. The semi-arc detection device has high inspection accuracy, a long using period and a relatively large inspection range.