Research On Key Technology Of NC Machining Of The Closed Guide Impeller

The closed guide impeller is an important energy conversion component in the The reactor coolant pump(RCP).The quality of the closed guide impeller directly affects the stability and efficiency of the long-term operation of the RCP.Similar to the impeller blade,the closed guide impeller has not only the complex surface characteristics,but also the characteristics of deep flow channel,narrow space and difficult material processing.The manufacturing of the closed guide impeller has always been one of the difficult problems in the field of mechanical manufacturing.In this paper,the research object is the key technology of NC machining on closed guide impeller.We studied from technology of 3D modeling,technology of NC programming,technology of closed impeller deep flow channel processing,measures of easing tool vibration process and technology of side milling.The specific research contents are as follow:(1)3D modeling method on the closed guide impellerIn the process of engineering,3D modeling is the premise and foundation of NC machining and digital manufacturing.Once wrong,the next job will lose its value and even bring out serious economic losses.Therefore,the accuracy of 3D modeling technology is very important.On the basis of studying the modeling technology of free-form curve and surface and the modeling of B spline,this paper propose the modeling method and steps of the closed guide impeller.It has been proved by practice that this method is reasonable and effective.(2)NC programming on the closed guide impellerAccording to difficult to divide the processing area,easy to collision between with the work piece and tool,handle or NC machine head,in-depth study of tool path planning and editing,NC program simulation,etc.,put forward a regional processing boundary representation and full size NC program simulation method.(3)Processing of closed guide impeller deep flow channelIn view of the geometric characteristics of the deep channel and narrow space of the closed guide impeller,a deep flow passage machining technology is developed from the aspects of tool selection,tool compensation and optimization of cutting parameters.From the machining results,the technology can effectively solve the problem of the cutter relieving and tool vibration caused by the tool overhang.(4)Side milling of closed guide impellerThe method of point milling and the side milling are studied,and a variety of algorithms for side milling are mainly studied.A new method of flank milling suitable for the open guide impeller is proposed,namely segmented slicing flank milling method.Experiments show that this method is effective and feasible.Further,the method is extended to the closed guide impeller.After repeated analysis,there are still many problems in the application of the method to the closed guide impeller,and the practicability is poor.This paper summed up a set of effective closed guide impeller machining technology.Through the successful implementation of the whole closed guide impeller NC machining,our company's first piece of closed guide impeller was finished in DMG125 P Five-axis Machining Center.machining of closed impeller fully meet the requirements of the drawings,and passed the experimental verification of the owners.The research results of this subject can be applied to the manufacture of other closed impeller and guide impeller with similar structure.