Modelling And Experimental Verification Of Forming Force,Energy And Surface Roughness Of Incremental Sheet Forming Process Based On Contact Area

Incremental sheet forming technology,as a dieless rapid prototyping technology,has broad application prospects in the field of small batch production.However,the forming mechanism of ISF is still in research stage,and the geometric accuracy of the formed parts is not perfect,which restricts its industrial application.The research on the contact area between the sheet and the forming tool in incremental sheet forming process can reveal the actual processing phenomena of incremental sheet forming process,which plays a vital role in the study of its mechanism.Research on the contact state of incremental sheet forming process was conducted in this paper,and the forming force,energy consumption and surface roughness of the workpiece of incremental sheet forming process was studied.Firstly,based on typical experimental phenomena,the contact area between the sheet and forming tool in incremental sheet forming process was analyzed in detail,according to the indentation on the plate,the contour line of the inner surface of the bottom edge on the workpiece,the wear condition of the forming tool and the erasable membrane on the forming tool.The contact area between the sheet and the forming tool was regarded as the space surface formed by the spherical surface of the forming tool intercepted by the side wall,the previous sub-cylinder surface and the unformed upper surface plane.Then,a three-dimensional model of contact area was established in MATLAB by means of Boolean operation.The change trend of the contact area with the process parameters was clarified,and the key points of the contact area was obtained through theoretical analysis.Secondly,the stress and strain analysis of the contact area between the plate and the forming tool was carried out to determine the force state of the element body.Then,the plastic deformation of this area was simplified to the plane strain problem in cylindrical coordinates.In addition,the key stress along thickness direction(?t)was obtained.Moreover,established contact area model was applied to the forming force calculation process and a complete three-dimensional forming force prediction model was established through surface integration.Afterwards,forming force experiments were carried out,the process parameters in the model were determined through exploration experiments.The accuracy of the model was verified through verification experiments.Then,according to the established model,the influence mechanism of the process parameters on the shape of the contact area and the forming force was analyzed in detail.Subsequently,the contact area model was simplified,and the energy consumption characteristics of incremental sheet forming process were studied,and the energy consumption model of the process was established.Applying the theory of energy decomposition,the processing power of incremental sheet forming process was decomposed into standby power,feed axis power and sheet forming power.The standby experiments,air forming experiments and processing experiments were carried out respectively,and the standby power,feed axis power and sheet forming power were obtained by calculating the difference among different processing stage.According to the milling process model,the standby power model and the feed axis power model were established,and the sheet forming power model was determined through the contact area between the sheet and the forming tool.The validity of the model was confirmed through verification experiments,and the influence mechanism of different process parameters on the power,power efficiency,energy,energy efficiency of incremental sheet forming process was analyzed in detail.Finally,an effective energy-saving processing strategy was obtained according to the prediction model.Finally,the contact area model was used for the surface roughness model,and the influence of the drawing and extrusion of the sheet on the surface roughness was considered.The geometric model of the surface roughness was obtained by theoretical method.On this basis,the influence of sheet thinning on the surface roughness was applied according to the forming angle of the formed sheet,and the influence of extrusion on the surface roughness was applied by the slip line method.After that,the model was optimized through experiments and simulation.Finally,the influence mechanism of the process parameters on the surface roughness was analyzed in detail and the model was developed through Genetic Algorithm.And the accuracy of model was verified.