Research On Quality Improvement And CNC Machining Technique Of Nozzles

Valve and fuel injection bar which are a series of parts in the nozzle spout subassemblies are seen as the precious parts on aero engines. In the present progress of production and development, due to the exact demands on technical requirement and dimension, particularly in the aspect of processing tiny parts and the longhole whose depth is tenfold of its diameter, parts are not qualified in technical requirement and dimension, because of insufficient tool strength and rigidity. In previous organization mode of production, this type of parts, especially the parts owning longhole, nearly depend on the operators' skill of machining on the common equipment, so the appearance quality and consistency of these parts are poor. On the contrary numerical control machining has the obvious advantage on machining precision and operating consistency.This paper is focused on the typical machining performance and quality process control of parts of grease series on aero engines, including air valve seat and afterburner performance, analyzes the main material and machining method of nozzles on aero engines, determines process route and process quality scheme of fuel injection bar and air valve seat, and gets much experience with nozzle machining. Through lots of tests and experiments, this thesis researches systematically on machining efficiency and quality management of air valve seat and fuel injection bar. The main content includes:(1)It analyses the status quo of aero engines at home and abroad, and the machining process of nozzles.(2)It researches quality improving method of nozzles, and makes process control scheme by PDCA circle.(3)It analyses the quality status quo of air valve seat, makes quality control point, implements quality improvement, analyses cutting performance of titanic materials, analyses machining path, analyses equipment ability and tool cutting capability, and resolves cutting difficulty.(4)It analyses the status quo of quality of fuel injection bar, makes quality control point, implements quality improvement, analyses tool cutting capability of high temperature alloy, analyses machining path of fuel injection bar, researches on longhole cutting of fuel injection bar, face milling, machining of fuel injection hole, optimizes machining techniques of parts as fuel injection bar, makes machining test of fuel injection bar, resolves difficulties of machining.By the research described above, this thesis analyses and improves the quality of nozzles by quality process method, analyses possibility of NC machining of nozzles, finds the most optimized technical scheme for air valve seat(Titanic alloy) and fuel injection bar(High temperature alloy), attains the goal of low cost and high efficiency on the precondition of ensuring the quality and precision, and offers one kind of solving scheme to improve the cutting efficiency of nozzle.