Deformation mechanics and efficient force prediction in single point incremental forming

Incremental sheet forming (ISF) is a promising forming process which is able to deform a flat sheet into a complex 3D shape by using a generic moving tool. The flexibility, increased formability and the reduced forming force make the ISF process ideal for rapid prototype and small batch production. However, the effective production design and optimization in ISF require the efficient prediction of forming force, especially the tangential force which is the actual force component that does plastic work during the forming process. In this paper, in order to investigate the deformation mechanism in the ISF process, a comprehensive finite element (FE) model for the cone-forming process with fine solid elements is established which allows the quantitative study of the deformation behavior of stretching, bending and shearing during the process. Based on such analysis, an efficient model for tangential force prediction is deduced analytically in which all these three deformation modes are considered. In particular, the contribution from each deformation mode is related to the variation of forming parameters. Additionally, the proposed efficient model is comprehensively validated with both truncated cone and pyramid shapes by varying four forming parameters (i.e. step down, wall angle, tool radius and sheet thickness). In both cases, the predicted forces show good agreements with the experimental results. Furthermore, the proposed model is generalized to deal with more complex shapes (e.g. ellipsoidal cup). It is found that the trend of tangential force could be properly represented by the change of the curvature of the formed part. Considering the proposed model can be solved within only several minutes, it will guide the forming process and shorten the lead time.

[1]  Paulo A.F. Martins,et al.  Revisiting the fundamentals of single point incremental forming by means of membrane analysis , 2008 .

[2]  Joost R. Duflou,et al.  Force prediction for single point incremental forming deduced from experimental and FEM observations , 2010 .

[3]  Julian M. Allwood,et al.  The mechanics of incremental sheet forming , 2009 .

[4]  Jian Cao,et al.  Deformation mechanics in single-point and accumulative double-sided incremental forming , 2013 .

[5]  Giuseppe Ingarao,et al.  A sustainability point of view on sheet metal forming operations: material wasting and energy consumption in incremental forming and stamping processes , 2012 .

[6]  Paul A. Meehan,et al.  Efficient force prediction for incremental sheet forming and experimental validation , 2014 .

[7]  Fabrizio Micari,et al.  A force measuring based strategy for failure prevention in incremental forming , 2006 .

[8]  Paul A. Meehan,et al.  Experimental Study and Efficient Prediction on Forming Forces in Incremental Sheet Forming , 2014 .

[9]  W. Hosford,et al.  Metal Forming: Mechanics and Metallurgy , 1993 .

[10]  Karl Kuzman,et al.  Autonomous on-line system for fracture identification at incremental sheet forming , 2009 .

[11]  S. Timoshenko,et al.  THEORY OF PLATES AND SHELLS , 1959 .

[12]  P. Meehan,et al.  Experimental investigation of mechanical properties, formability and force measurement for AA7075-O aluminum alloy sheets formed by incremental forming , 2013 .

[13]  A. H. van den Boogaard,et al.  An overview of stabilizing deformation mechanisms in incremental sheet forming , 2009 .

[14]  Paul Vanherck,et al.  Experimental study on force measurements for single point incremental forming , 2007 .

[15]  Julian M. Allwood,et al.  A structured search for applications of the incremental sheet-forming process by product segmentation , 2005 .

[16]  Jian Cao,et al.  Mechanism investigation of friction-related effects in single point incremental forming using a developed oblique roller-ball tool , 2014 .

[17]  Antonio Fiorentino,et al.  Force-based failure criterion in incremental sheet forming , 2013 .

[18]  Bijan Mollaei Dariani,et al.  Analysis of incremental sheet metal forming using the upper-bound approach , 2012 .

[19]  Paul A. Meehan,et al.  Simulation and Experimental Observations of Effect of Different Contact Interfaces on the Incremental Sheet Forming Process , 2014 .

[20]  M. Muzzupappa,et al.  Application of Incremental Forming process for high customised medical product manufacturing , 2005 .

[21]  Jun Gu,et al.  Strain evolution in the single point incremental forming process: digital image correlation measurement and finite element prediction , 2011 .

[22]  Fabrizio Micari,et al.  Incremental Forming Process for the Accomplishment of Automotive Details , 2007 .

[23]  H. Iseki,et al.  An approximate deformation analysis and FEM analysis for the incremental bulging of sheet metal using a spherical roller , 2001 .

[24]  Fabrizio Micari,et al.  On-Line Control of Single Point Incremental Forming Operations through Punch Force Monitoring , 2006 .

[25]  Stephen R. Duncan,et al.  Rigid plastic model of incremental sheet deformation using second‐order cone programming , 2009 .