Research Of Clamping Deformation Of The Weak-rigidity Hollow Disk

Weak-rigidity workpiece is easy to deform because of structural feature, form element and material characteristics. This article takes a typical weak-rigidity structure component,a thin-wall gear ring, as research object and researches on the influence of clamping deformation to machining precision on weak-rigidity hollow disk through the method of the theoretical analysis, numerical calculation, finite element simulation and experimental verification. The purpose is to control the machining deformation of weak-rigidity hollow disk by the optimization of clamping force and clamping method. The main wok is as follows.Firstly, based on the workpiece positioning and clamping basic theory, the positioning matrix of hollow disk is deduced. Necessary and sufficient conditions are analyzed to judge poisoning accuracy and clamping stability. The methods are put forward to design the clamping of hollow disk and calculate the clamping deformation.Secondly, based on the empirical formula of cutting force, calculation model for gear ring material is established by orthogonal experiment. A function relationship between clamping force and cutting parameters is obtained when turning the gear ring workblank by analyzing the force conditions of clamping jaw. The function relationship can be used to calculate the minimum clamping force of every turning process.Thirdly, the clamping deformations, produced by three- jaw chuck and fan chuck, are calculated separately through the unit load method. A function relationship is established between clamping deformation and fixture parameters. The best fan central angle which makes clamping deformation minimum is obtained by optimizing the function.Lastly, a Johnson-Cook constitutive model of 20Gr2Ni4 A is set up through static and dynamic force experiments. Based on the model, gear ring clamping is simulated by Abaqus and the deformation effects of the two clamping methods are contrasted. A conclusion is drawed that fan chuck can decrease clamping deformation effectively. Finally,the simulation result is verified through an experiment of turning gear ring workblank.