Vacuum preloading hydrostatic support technology for mirror milling of thin-walled parts

Abstract

Abstract High quality and high efficiency machining of thin-wall, low-stiffness and large-scale skin parts with complex curved surface is in great demand in the aerospace field. Mirror milling is an efficient and green processing technology for large-scale skin parts. The support technology of mirror milling is the key technology to ensure the machining accuracy and surface quality. Aiming at the problems of poor machining accuracy and surface quality, as well as the scratches on the support surface in the sliding and rolling support modes, a new technology of vacuum preloading hydrostatic support was proposed. The machining accuracy and surface quality of thin-wall parts by mirror milling with vacuum preloading hydrostatic support are systematically studied. The main study and findings are as follows: The vacuum preloaded hydrostatic supporting head was designed. The theoretical analysis of the liquid film stiffness and thickness were carried out. The vacuum preloaded hydrostatic support system was designed and developed. Mirror milling experiments of thin-walled parts supported by vacuum preloading hydrostatic pressure was carried out to compare the surface profile and surface roughness under different fluid feed pressure and vacuum preloading. It is concluded that within a certain range: the smaller the vacuum preload and the larger the inlet pressure, the closer the milling depth is to the target depth; the larger the inlet pressure and the larger the vacuum preload, the better the consistency of workpiece thickness of the milled surface; and the presence of the liquid film effectively reduces the roughness of the milled surface.