Clamping Method For Thin Shell Parts With Deformation Compliance

A kind of thin-walled rotary parts with light weight and high performance are widely used in the fields of aerospace,national defense and military industry.In view of the extreme working conditions of high speed and overload,such thin-walled rotary parts are required not only to have sufficient strength and stiffness,but also to ensure high functional requirements.In the case of material determination,the assurance of functional requirements depends on the precision of the processing.Due to the low overall rigidity and large flexibility of the thin-walled rotary parts,it is easy to produce large clamping deformation during the clamping process,and the clamping deformation has irregular characteristics.And the uncertainty and irregularity of clamping deformation become particularly prominent,which not only affects the high-quality processing of thin-walled parts,but also greatly limits the improvement of processing efficiency.Therefore,designing the reliable clamping device for such thin-walled rotary parts and the research of controlling the deformation of thin-walled rotary parts have a high theoretical and practical engineering application value.In this paper,the typical thin-walled rotary parts are taken as the research object,and the main research objective is to achieve the uniformity of workpiece clamping deformation.Through the design of stable and reliable clamping device which meets the complex processing requirements of thin-walled rotary parts,the location parameters optimization of positioning elements is determined based on position error and positioning stability constraints.Based on the finite element analysis method,a mathematical model of the uniformity coefficient of the fixture is established,and the position parameters of the clamping element under the uniform constraint are obtained.The main research contents of this paper are as follows:Firstly,a special fixture with stabilizing clamping and centering ability is designed,which can be used on two-dimensional rotary table or mechanical arm flange,in order to realize precise machining of metal coating on inner and outer surfaces of thin-walled rotary parts once installed.The special fixture uses precisely manufactured auxiliary positioning elements and flexible sliding positioning clamping components to coordinate positioning and clamping workpiece,which solves the difficult problem of centering conical thin-walled rotary parts;By contacting the workpiece with the spherical head of the sensor,the clamping force and supporting reaction are measured in real time,at the same time,the inner and outer surfaces of the workpiece are processed by the rotation of the worktable.The overall device is simple to operate and reliable in performance.Then,on the basis of the stable clamping,the location parameters of positioning elements are optimized to reduce the positioning error of thin-walled rotary parts in fixtures and improve the stability of workpieces in fixtures.By dissecting the clamping process of the workpiece in the fixture,the clamping process is divided into rigid positioning stage and flexible clamping stage.In the rigid positioning stage,the workpiece-clamp contact rigid body model is established to solve the workpiece-clamp system contact stiffness;In the flexible clamping stage,by solving the overall stiffness matrix of the workpiece-clamp system during the clamping process,the contact force solving model of the workpiece clamping stage is established,and the contact force of the workpiece after clamping is obtained.Finally,by establishing the workpiece stability coefficient model and the rigid-flexible workpiece position error solving model,the position parameters of the positioning elements which ensure the optimal positioning stability and minimize the position error of the workpiece are obtained.Finally,combined with the optimized position parameter combination of positioning elements,the parametric modeling of thin-walled rotary parts is carried out by APDL program.The objective function of uniform deformation is established by using MATLAB programming language,and the joint simulation operation of MATLAB and ANSYS is carried out by using the programming language,And the deterministic deformation of each position in the clamping process and the optimization of clamping element position parameters based on uniform deformation are obtained.The above research results provide a reference for the further study of the deterministic problem of deformation during the clamping process of thin-walled rotary parts,at the same time,also provided positive guiding significance for actual production processing.