Marking device of bending line of mining truck U-shaped part and using method

The invention discloses a marking device of a bending line of a mining truck U-shaped part. The marking device of the bending line of the mining truck U-shaped part comprises a sample plate body; a long hole is formed in the sample plate body; a plurality of linear protrusions are arranged on the side edge of the upper part of the sample plate body; the linear protrusions are in a right triangle shape; one right-angle side of each linear protrusion is connected with the side edge of the sample plate body; the edge of the other right-angle side is used as a positioning side, and the positioningside is used for drawing a marking short line of the bending line; and the side edge of the lower part of the sample plate body is a straight line edge which is used for drawing a straight line section for connecting the two marking short lines. The invention further discloses a using method of the marking device of the bending line of the mining truck U-shaped part. According to the marking device of the bending line of