Inner cold spiral-hole twist drill

The utility model relates to an inner cold spiral-hole twist drill. At present, the conventional twist drills in China have outer cold structures, so that the cutting temperature is high, chips cannot be removed smoothly, a drill bit is quickly worn, and the service life of a cutter is finite. The cooling and lubricating effects of a cutting fluid are poor, and the drill bit is embrittled and fractured often and the durability of the drill bit is reduced; meanwhile, water supply is not sufficient, so that the drilling speed is limited to some extent and the work efficiency is low. The inner cold spiral-hole twist drill comprises a drill stock (1), wherein the drill stock is connected with a drill body (2) which is provided with a radial through hole (3); the drill stock is provided with an axial through hole (4) communicated with the radial through hole; and the drill body is provided with two parallel spiral holes (5) communicated with the radial through hole. The inner cold spiral-hole twist drill serves as