Tunnel lining thickness detection device

A tunnel lining thickness detection device comprises a base, a plurality of positioning sliding rods are mounted on the upper surface of the base, a lifting plate is mounted on the outer surfaces of the positioning sliding rods, a mounting frame is mounted on the upper surface of the lifting plate, a mounting shaft is mounted on the inner surface of the mounting frame, and a rotating block is mounted on the outer surface of the mounting shaft. The mounting box is pushed to rotate around the mounting shaft by controlling the air cylinder, so that the angle of the drill bit is conveniently adjusted; then a drilling motor is controlled, and a connecting shaft is installed, so that a drill bit is driven to rotate, and drilling is facilitated; a lifting motor is controlled, meshing between a power bevel gear and a transmission bevel gear is utilized to drive a threaded rod to rotate, then connection between the outer surface of the threaded rod and the inner surface of a threaded sleeve is utilized to drive a lift