Spindle power-on device for mechanical discharge compound machine tool

A spindle power-on device for a mechanical discharge compound machine tool mounted on a spindle, the spindle power-on device comprising a copper bush, a gear plate, bevel gears, electric bush assemblies, a chuck housing, a supporting plate, a mounting plate and a power device, wherein the gear plate and the bevel gears are mounted inside the chuck housing in a meshed manner, a top of the chuck housing is connected with the mounting plate, a bottom of the chuck housing is supported by the supporting plate, the supporting plate is made of insulating material to insulate the spindle power-on device from the machine tool, each of the electric brush assemblies is mounted in a groove in the chuck housing, a bottom bearing of each electric bush assembly is placed in a groove of the gear plate, the copper bush is mounted on the spindle, an electric brush of each electric brush assembly is pressed against an outer surface of the copper bush, and the copper bush, the spindle and remaining components of the power-on device are ensured to be coaxial.