Research On The Accuracy Of Static Pressure Support Ultrasonic Vibration Single Point Incremental Forming

Single point incremental forming(SPIF)is a new type of sheet plastic incremental forming technology without molding.In the forming process,using the idea of "layered manufacturing"in rapid prototyping manufacturing technology,the forming tool forms the sheet metal layer by layer according to the predetermined path,making it plastic deformation and finally get the target part.This technology has the advantages of high flexibility,high efficiency,low energy consumption and low cost.However,due to the lack of specific mold constraints,the sheet material is prone to instability,springback and other defects during the partial loading of the forming tool head,making it difficult for the accuracy of the workpiece to meet the actual process requirements.In this paper,the two auxiliary technologies of static pressure support and ultrasonic vibration are simultaneously applied to the single point incremental forming process,forming a new technology of static pressure support ultrasonic vibration single point incremental forming(SPSUV-SPIF)with multi-physics simultaneous action,in order to improve the mechanism between the tool head and the sheet metal while improving the forming accuracy of the part.Using a combination of theoretical analysis,finite element simulation and experimental verification to study the effect of static pressure support and ultrasonic vibration assisted forming on the single point incremental forming process,focus on studying the effect of static pressure support and ultrasonic vibration assisted forming on the axial error of the part,and provide new methods and ideas for improving the accuracy of single point incremental forming,and is of great significance to promote single point incremental engineering applications.By analyzing the principle of static pressure support ultrasonic vibration single-point incremental forming,a micro-element mechanical model of the sheet contact area is established,the analytical model of forming force in sheet metal forming process is obtained.On this basis,the axial error of the part is defined,and the cause of the axial error of the part is analyzed.Adopt ABAQUS finite element analysis software to systematically analyze the forming process,by changing different static pressure and ultrasonic vibration parameters,the effects law of two auxiliary processes on axial error,forming force,stress and strain distribution and residual stress is studied,the improvement mechanism of static pressure and ultrasonic vibration on sheet metal forming quality is explored.Build a static pressure support-ultrasonic vibration single-point incremental forming experimental platform,combine the simulation parameters to formulate the experimental plan,collect the forming force during the experiment,measure the residual stress and axial error data of the formed part,by comparing the experimental results with the finite element analysis results,the accuracy of the simulation model and the validity of the simulation results are verified.The surface waviness of the workpiece is measured,and the influence of static pressure ultrasonic assisted forming on the surface waviness is analyzed.The Box-Behnken Design(BBD)response surface experiment is designed,and the axial error data under different static pressure and ultrasonic vibration parameters were obtained through the experiment.The influence of single factor and multi-factor interaction on the axial error of the workpiece is analyzed and revealed the static pressure value,amplitude and frequency improve the specific interaction relationship of the axial comprehensive error of the workpiece.The optimal combination of process parameters under the studied conditions is:static pressure value 0.073 MPa,amplitude 0.0203 mm,vibration frequency 17.8788 KHz,forming angle 39.0909°,from the perspective of forming parameter optimization,a method to reduce axial errors in the forming process is obtained.