Composite screw tap

The utility model provides a combined type screw tap which comprises a screw tap body, and a first through cavity is formed in the screw tap body. The outer wall of the screw tap is provided with a machining part and a handle part, the machining part is provided with a plurality of oil outlet holes communicating with the first through cavity, and the oil outlet holes are distributed in the axial direction; the oil liquid shell is fixedly mounted at one end of the screw tap, and an oil storage cavity is formed in the oil liquid shell; a liquid inlet communicated with the oil storage cavity and an air outlet communicated with the oil storage cavity are formed in the oil liquid shell; a weighting piston is slidably arranged in the oil storage cavity; the oil injection assembly comprises an oil conveying pipe, and one end of the oil conveying pipe extends into the oil storage cavity; the other end of the oil conveying pipe extends into the first through cavity; the air bag ball is mounted at the handle part of th