Main shaft unit of longitudinally cutting machine tool

The utility model relates to a main shaft unit of a longitudinally cutting machine tool. The main shaft unit is characterized by comprising three structures. The first structure is that a main shaft bearing is of a split type structure formed by a front bearing and a back bearing, the front bearing is of a fixed mode, the back bearing is of a floating mode, and the front bearing and the back bearing are installed at the front end and the back end of a sleeve respectively. The second structure is that a rod material clamping mechanism is arranged at the middle portion between the front bearing and the back bearing to reduce the length of a main shaft, the main shaft is connected with a clamping mechanism through a sliding key to achieve sliding, the clamping mechanism is composed of a clamping claw, a pin shaft, a sliding base and a clamping bearing, and the upper portion of the sleeve wall is opened to enable the clamping mechanism to be exposed. The third structure is that sealing is carried out, a front end