Helical Milling Of Difficult-to-cut Materials

Due to their high strength, good fatigue strength and corrosion resistance, more and more difficult-to-cut material such as carbon fiber reinforced plastic (CFRP), titanium alloy and aluminum alloy are used in large components in aerospace industry. The laminate component form by composite and alloy are usually assembled by rivets or bolts, thus the precision and the quality of the connecting hole determined the reliability and the life of aerospace C/A components. Because of the large quantities and high quality of the hole requirement, traditional drilling with twist drill cannot satisfy the integrate hole-making requirement of C/A components.Aim at the problem of making holes in C/A components with traditional twist drill, based on the requirements of flexible assembly technics, the paper brought helical milling in integrate high efficiently making holes in C/A components with single process and several things following were investigated:(1) Studied the tool edge path with kinematics theory and mathematical simulation software Matlab, and helical milling kinematics theoretical model was set up. The path of tool tip and cutting edges during processing were simulated and the geometry of the undeformedchip was further studied.(2) By analyzing the geometry of undeformedchip, investigated the theoretically differences between helical milling and traditional drilling, and the reason why helical milling is better than traditional drilling. Meanwhile the probable impacts on processing caused by different relative rotating direction of rotation and orbital rotation of tool has been studied, and the machine results were predicted.(3) The design plan and the optimization was completed according to the machine principle of helical milling as well as the matching connection of tool rotation, tool orbital rotation and axial feed.3D virtual prototype of helical milling device was established by using3D design software Pro/E, and finally designed helical milling device which can be used in high efficiency&precision hole-making of large components flexible assembly.(4) Technical test of C/A laminate helical milling process was carried out, the cutting force, cutting temperature, hole precision and defects under different processing parameters were measured. The law of the effect of helical milling tool rotating speed, orbital rotating speed and axial feed speed on cutting force, cutting temperature, hole quality, surface roughness, defects, and cutting efficiency. The control strategy and proper technic parameters of machining different materials (composite, alloy, transitional interfaces) of C/A components were fixed.