Free telescopic reamer while drilling and drilling and expanding tubular column

The invention discloses a free telescopic reamer while drilling and a drilling and reaming tubular column, belongs to the technical field of petroleum drilling, and aims to solve the problem that the reaming range of an existing reamer cannot be adjusted. The free telescopic reamer while drilling comprises a shell (2) and a reaming structure, an upper driving unit (21) and a lower driving unit (23) are arranged in the shell (2) in an up-down mode, and the upper driving unit (21) is connected with the lower driving unit (23). The reaming structure comprises an auxiliary rod (5), an outer rotating shaft (4) and a main scraping rod (6) which are sequentially connected from top to bottom in the axis direction of the shell (2), and in the process that the upper end of the auxiliary rod (5) moves downwards and the lower end of the main scraping rod (6) moves upwards, the outer rotating shaft (4) moves in the direction away from the axis of the shell (2) along the diameter of the shell (2). The extending distance of