Arc infolding rotating mechanism with invariable tangent point

The invention discloses an arc infolding rotating mechanism with an invariable tangent point. The arc infolding rotating mechanism comprises a rotating shaft; the rotating shaft comprises a rotating mechanism; the rotating mechanism comprises two rotating frames which are transversely distributed; an arc groove movable block and two arc sliding blocks which are longitudinally distributed and rotationally connected are arranged between the rotating frames; arc sliding grooves glidingly connected with the arc sliding blocks are formed in the two sides of the arc groove movable block; the arc sliding blocks slide in the arc sliding grooves in a reciprocating mode to achieve U-shaped inward-bending rotation with the tangent point of a 0-180-degree motion trail unchanged; the rotating frames and the arc groove movable block rotate through sliding fit of a sliding column and a curved groove; rotating holes are formed in the rotating frames; rotating columns are arranged on the arc sliding blocks; and the rotating frames and the arc sliding blocks are rotationally connected through running fit of the rotating columns and the rotating holes.