Electric principal axis with automatic loose broach

The present utility model discloses an electric principal axis with automatic loose broach, which comprises a principal axis, a stator, a rotor, a cylinder and a broach structure which is received inside the principal axis and comprises a drawing claw 2, a handspike 15, a spring 14 and an induction ring 10, wherein two ends of the handspike 15 are connected to the peripheral screw of the drawing claw 2 and the inner side screw of the induction ring 10; the spring 14 is mounted to the peripheral of the handspike 15 with its one end contacting the principal axis 16 and the other end contacting the induction ring 10. There is also provided a limit switch 3 in a position corresponding to the induction ring 10 in the inner chamber in the cylinder body 5, which is connected to the cylinder body 5 through a switch base. With such a structure in accordance with the present utility model, the loading and unloading of a tool is capable of being performed automatically. Therefore, the present utility model improves effectively the efficiency and is mainly used for loading and unloading a tool of an electric principal axis rotating with a high speed.