Printing paper path with constant tensile force in printing system of rotary offset machine

The utility model relates to a printing paper path with constant tensile force in printing system of rotary offset machine, which comprises a paper feeding mechanism, a first printing unit, a second printing unit, a third printing unit, a fourth printing unit and a hinge mechanism; the utility model is characterized in that a front constant tension mechanism is arranged on a wallboard through a bearing component before the front half paper of the first printing unit enters a printing roller, a rear constant tension mechanism is arranged on a wallboard through a bearing component after the rearhalf paper of the fourth printing unit leaves the printing roller. The front constant tension mechanism and the rear constant tensile force mechanism respectively comprise an intermediate gear, a transmission gear, a transmission surface wallboard, a tension roller, a clutch shaft, a swing arm for controlling a press wheel, a tension press wheel, an operation surface wallboard and a cylinder component. The utility model