Research On Hierarchical Optimization Of Milling Process For Multi-variety And Small Batch Structural Parts Based On Adaptive Clamping

Aviation small structural parts have typical characteristics of multiple branch and small batch.Basically,a certain type of aircraft has hundreds of different parts,and the processing number for each type of parts is several or only one,the structure of the aircraft is very complicated due to various and complex shapes of cavity groove,hole and reinforcing plate.High precision machining the parts faces a large challenge because of above statements.At present,the traditional "single one" CNC machining mode behaves a low efficiency of process design and programming,its process depends on the experience of the processing staff,the coordination mechanism between each process link is unperfect and other prominent problems.Which result in the low productivity and the processing quality cannot be guaranteed for current processing mode.Therefore,it is of great significance to optimize the cutting process of multi-variety and small-batch aeronautical structural parts.This paper elaborates a hierarchical optimization strategy that improves efficiency of processing and quality of structural parts to solve the problem of machining process optimization involved for multi-variety and small-batch structural parts.The main research contents descripted as follows:(1)Based on the features of flexible production unit,in order to solve "difficult clamping" problem of small structural parts,the adaptive clamping method was adopted to establish the clamping force finite element model,with its feasibility analyzed and verified.Analyzing the machining traits of various kinds of small structural parts and determining the processing methods,A hierarchical optimization scheme of machining process for small structural parts is proposed.(2)Based on adaptive clamping scheme,the overall machining procedure of structural parts is divided into three processes: top surface,side surface and bottom surface.Through the analysis of the same working condition and different routes,deformation size of the structural unit under action of cutting force is established,furthermore,setting up finite element model to decrease processing variants.Above operations optimizes the process routes of multi-variety and small-batch aeronautical structural parts.(3)In the view of the main processing features of aviation small structural parts,analyze the tool selection and tool path mode during the machining process,plan and analyze the way of advance and retreat tool paths,analyze the isometric surface tool path to generate algorithm for the cavity and groove feature processing;Planning the tool path with analyzing the influence of cutting distance on surface quality of stiffened plate.(4)Aiming at the optimization problem of small structural parts,maximize the material removal rate and minimize the cutting temperature own the priority.Setting a reasonable weight coefficient and constraint conditions,establishing process parameter optimization models based on multi-objective optimization algorithm,obtaining relatively optimal combinate of process parameter and significantly improve the efficiency in processing.Applying the above research results to the production practices of multi-variety and small batch aviation structural parts,the processing efficiency is effectively improved under the premise of ensuring the processing quality,furthermore,the time and cost of design and manufacturing for a variety of complex tooling fixtures are saved,which effectively solve the problem of low processing efficiency and difficult in guaranteeing process quality of aviation small structural under the discrete manufacturing mode.It plays a positive role in breaking through the bottleneck in the processing of aviation structural parts and improving the manufacturing level of aviation structural parts in China.