Research On Key Technology Of Micro-drilling

Micro-drilling is the main processing method of tiny hole. Micro-drilling is different from conventional drilling in drilling tool structure, mechanism and other aspects. Microdrilling technology becomes the focus of study. Based on the combination of theory, simulation and test, the key technology of micro-drilling is studied. The content includes:1) The characteristic of micro-drilling is analyzed. The tool of micro-drilling is fine. The minimum cutting thickness exists in the metal cutting model because of the cutting edge arc. The strength and the rigidity of cutting tool is poor. The broken of cutting tool is the main breakage form. To increase the strength and the rigidity of the cutting tool, the core diameter ratio is big and the margin does not exist. Axial force is low under the high speed drilling. Radial force exists because of the influence of cutting tool rigidity and work piece material. Radial force is the main cutting force and the main factor of cutting tool break.2) The main geometric parameters of the tiny twist drill are analyzed. Spiral angle, apex angle and core diameter influence the size of anterior angle, chisel edge and tool cutting edge inclination to affect the cutting tool structure and drilling process indirectly. By the optimizing of orthogonal simulation test, the optimal size, the spiral angle of 25°, apex angle 130°, core diameter of 0.25 mm is found.3) The influence of drilling parameters on drilling force, drilling temperature, breakage, chip, quality of hole and other factors is analyzed. The higher the speed is, the better the quality of micro-drilling is. The low feed is favor of drilling force, temperature, wear, the quality of hole and chip. But if the feed is close to the minimum cutting thickness, the cutting force, temperature will increase and the wear, chip will be serious.In order to make tool model and drilling model in line with the real, the 3d model of tiny twist drill and the simulation model of micro-drilling are created particularly. Finally, the experimental results deviation is 12.06% from simulation. This result verifies the effectiveness of micro drilling simulation.