Abstract: To solve the problems that traditional drilling technology is difficult to meet the damage repair requirement of new titanium alloy thin-walled and high energy technology can not adapt to the repair field, analyze the lubricant mechanism of combined mist-jet(CMJ) and its influence on drilling force, the portable pneumatic generator of CMJ and titanium alloy covering in situ drilling tools are developed. Ti6Al4V (TC4) drilling test is carried out fewer than three kinds of conditions such as dry cutting without lubrication, minimum quantity lubrication (MQL) and CMJ lubrication. Experiment results indicate that with 80 ~ 100 mL/h oil and 200 ~ 400 mL/h water consumption，the CMJ lubrication has the best effect during drilling the TC4 2 mm thickness sheet. Compared with the MQL lubricant with the same amount of oil, axial drilling force decreases 24% during CMJ lubrication; exit burr height is lower more than 29; in its usage life, the amount of whole can be drilled increase 42% than original. The results show that the designed CMJ lubricating system and its corresponding tools are useful for improving the repair efficiency and drilling quality and laid the foundation for field repair ability for titanium alloy structural damage of new type battle plane and battle damage repair.

Key words: combined mist-jet, drilling, micro-lubrication, structure repair, titanium alloy TC4