Method And System Development Of The Digital Thinning For Large Thin-walled Parts

Large thin-walled parts are a kind of important structural parts in the field of national defense and aerospace in China.Lightweight and high strength are their common structural requirements,which put forward the demand for controllable residual wall thickness.In order to effectively reduce weight and ensure sufficient structural strength,the thin-walled parts need to be processed by equal wall thickness or variable wall thickness.We call it thinning processing.However,due to the blank forming error,clamping deformation and the dead weight of the parts,the thin-walled parts have the characteristics of unknown shape,uneven wall thickness distribution and weak stiffness,which leads to the remaining wall thickness of the parts is difficult to control.Therefore,for the controllable demand of the remaining wall thickness of large thin-walled parts,this paper carried out research on the digital thinning processing method of large thin-walled parts.Aiming at the problem of controlling the thickness of large thin-walled parts,a unified wall thickness error model is established,and the influence of multi-source errors on the remaining wall thickness of parts is analyzed.The wall thickness error of the thin-walled parts is attributed to the deformation problem,and the deformation problem of the thin-walled parts is divided into the integral deformation of the parts and the deformation in machining.The integral deformation compensation method based on dimension correlation is studied,and the tool position compensation model for machining deformation is established.The calculation method of compensation based on multi-wheel in-machine measurement is studied.The error model of deformation in machining is established,and the relevant parameters are estimated based on in-machine measurement and machining data.Considering the coupling effect of the compensation amount and the deformation in machining,the compensation amount satisfying the expected machining wall thickness is calculated.Based on the minimum energy method,the tool path generation method is studied.A tool path close to the compensation point and smooth enough is obtained for the single modified scattered compensating tool point,which further improve the effect of deformation compensation.It provides an important theoretical basis for the digital thinning of large thin-walled parts.In order to verify the theoretical research and realize the engineering value,based on the HNC-8 numerical control system,a software system for digital thinning and thinning of large thin-walled tube segment is developed.This paper analyzes the thinning processing requirements of large thin-wall tube segment,determines the functional requirements of thinning processing software system,and studies the secondary development technology of HNC-8 numerical control system.Aiming at the complexity problem of software system integrating measurement,data processing,deformation compensation and automatic processing,the general framework and key algorithms of software system are designed.The main functional modules of thinning processing software system are designed.The software system has the characteristics of parameterization of network connection,universality of parts,automatic generation of compensation track,automatic generation of machining code and humanization of inspection and display,etc.Based on the research theory and software system,the thinning processing technology of large thin-walled tube segment is designed,and the hardware equipment used in thinning processing is introduced.Three rounds of thinning processing experiments were carried out for a certain type of large variable wall thickness-thin wall cylinder,and the experimental results were analyzed and summarized,which verified the validity of the theory and software system studied in this paper.