Research On PEI Sheet Viscous Warm Pressure Forming Process

A viscous warm pressure forming method has been proposed to reduce the cost in small batch for complex shape thin-walled parts of polyetherimide(PEI),which is based on the mechanical properties of PEI and combines with the advantages of viscous pressure forming technology.In addition,filling pure aluminum particles into viscous medium has been proposed to improve the low thermal conductivity of viscous medium during experiment process,which optimizes viscous warm pressure forming technology.Firstly,the tensile tests of PEI sheet have been carried out at different temperatures according to the thermal properties of PEI sheet.The influence of temperature and forming speed on the formability of PEI sheet has been obtained.Meanwhile,the influence of temperature on compression and fluidity properties of viscous medium have been determined by compression and fluidity experiments.Then,the limit bulging height,profile change and wall thickness distribution of PEI sheet have been obtained by viscous warm pressure bulging experiments and finite element analysis.The stress,strain and velocity field distribution of PEI sheet also have been determined during viscous warm pressure bulging process.Finally,the settlement velocity of pure aluminum particles in viscous medium and the influence of pure aluminum particles on compression property of viscous medium have been obtained by settlement and compression experiment at different temperatures,respectively.The influence of pure aluminum particle size and mass fraction on the thermal conductivity of viscous medium have been determined by experiment.In addition,the influence of filling pure aluminum particles on specimens and viscous medium heat transfer process have been determined by viscous warm pressure bulging and finite element analysis,which proved the feasibility to improve the forming efficiency of viscous warm pressure forming.