Automatic replacing device applied to 3D printer test paper

The invention relates to an automatic replacing device applied to 3D printer test paper. The automatic replacing device comprises a box, bearing sets, a telescopic air cylinder, a stepping motor and a print paper supply box. The two bearing sets are fixedly arranged at the upper end of the box and provided with the telescopic air cylinder for paper penetrating. The telescopic air cylinder is provided with a large wheel of a synchronous belt wheel set in a matched manner. A small wheel of the synchronous belt wheel set is arranged at the upper end of the stepping motor. The large wheel and the small wheel of the synchronous belt wheel set are combined through a synchronous belt. The print paper supply box is arranged in the box. A baffle is vertically arranged in the middle of the box. A spring is arranged at the bottom of the print paper supply box. Test print paper cores are arranged on test print paper rolls. The test print paper rolls are arranged in the print paper supply box through the test print paper