The invention provides a method used for drilling tool thread repair by using a numerically controlled lathe, and belongs to the field of thread
machining. The method comprises the steps that firstly,tool selection is conducted; secondly, a thread turning starting point is determined; thirdly, tool setting is completed, wherein the fact that a tool
nose does not collide with a workpiece to be repaired is used as a basis in the X direction, in the Z direction, the tool
nose is located in the middle of threads and then moved into a spiral groove of the threads, the radial X and axial Z positionof the tool
nose is slightly adjusted until the tool nose coincides with the spiral groove,
single step run is selected, reading is conducted through public variables, and tool setting operation is completed; fourthly, the tool nose is moved to the position of N thread pitches of the tool setting spiral groove to serve as an
initial point of continuous
machining; and fifthly, continuous machiningis carried out to complete thread repair. According to the method, the inaccuracy caused by human factors is eliminated, the drilling tool repair quality is improved, dimensional stability is realized after thread repair, the numerically controlled lathe runs automatically, the labor intensity is reduced, and the efficiency is high.