Scalability of conventional tube hydroforming processes from macro to micro/meso

Due to the increasing demand for small, complex parts, researchers are putting a great deal of effort into applying the metal forming process to the micro and meso world. However, the tube hydroforming process is yet to be fully realized on this small scale because of the difficulties which arise in scaling the conventional tooling to the microscale. This article discusses the difficulties that arise as a result of simply shrinking the traditional hydroforming tools to the microscale. A simple mathematical model is then proposed as a way to help designers determine the limits of the conventional punch with a tapered nose commonly used in tube hydroforming. The model is then validated by performing a finite element analysis of the punch, and the results of the model are discussed in relation to the scaling concepts posed at the beginning of this article. It is determined that as the punch shrinks down, the stresses on the punch rise significantly as a result of changing aspect ratios of the workpiece and the inability to accurately machine very small holes through the punch body. A nonconventional tube hydroforming method may therefore be required to perform micro-tube hydroforming operations, especially on harder materials.

[1]  B. Guo,et al.  Flow stress and tribology size effects in scaled down cylinder compression , 2009 .

[2]  Gracious Ngaile,et al.  Database for real-time loading path prediction for tube hydroforming using multidimensional cubic spline interpolation , 2009 .

[3]  Fpt Frank Baaijens,et al.  Size effects in the processing of thin metal sheets , 2001 .

[4]  Gracious Ngaile,et al.  Applications of analytical model for characterizing the pear-shaped tribotest for tube hydroforming. Part 2 , 2008 .

[5]  Yi Qin,et al.  A Review on Micro-manufacturing, Micro-forming and Their Key Issues , 2013 .

[6]  Christoph Hartl,et al.  Investigation into reduction of die-cavity deflection in micro-hydroforming processes using FEA , 2010 .

[7]  M. Fu,et al.  A constitutive model for modeling of the deformation behavior in microforming with a consideration of grain boundary strengthening , 2012 .

[8]  Gracious Ngaile,et al.  Analytical model for characterizing the pear-shaped tribotest for tube hydroforming. Part 1 , 2008 .

[9]  Ulf Engel,et al.  Tribology in microforming , 2006 .

[10]  Gracious Ngaile,et al.  Punch design for floating based micro-tube hydroforming die assembly , 2018 .

[11]  Muammer Koç,et al.  Investigation of size effects on material behavior of thin sheet metals using hydraulic bulge testing at micro/meso-scales , 2008 .

[12]  C. Chang,et al.  Influence of grain size and temperature on micro upsetting of copper , 2012 .

[13]  Jianguo Lin,et al.  Experimental and numerical investigation of localized thinning in hydroforming of micro-tubes , 2012 .

[14]  Myoung-Gyu Lee,et al.  Recent developments in hydroforming technology , 2015 .

[15]  Miroslav Plančak,et al.  Analysis, finite element simulation and experimental investigation of friction in tube hydroforming , 2005 .

[16]  Chen Yang,et al.  Analytical Model for the Characterization of the Guiding Zone Tribotest for Tube Hydroforming , 2008 .

[17]  Manfred Geiger,et al.  Mechanical properties and bending behaviour of metal foils , 2008 .

[18]  U. Engela,et al.  Microforming at elevated temperature – forming and material behaviour , 2005 .

[19]  Jörn Lungerhausen.  Fundamental studies on tube hydroforming and laser assistance in the manufacture of micro-parts , 2012 .

[20]  Golta Khatibi,et al.  The ‘size effect’ on the stress–strain, fatigue and fracture properties of thin metallic foils , 2001 .

[21]  M. Fu,et al.  Experimental and simulation studies of micro blanking and deep drawing compound process using copper sheet , 2013 .

[22]  T. A. Kals,et al.  Miniaturization in sheet metal working , 2000 .

[23]  Taylan Altan,et al.  On the characteristics of tubular materials for hydroforming—experimentation and analysis , 2001 .

[24]  P. Groche,et al.  Fundamentals of Angular Joining by Means of Hydroforming , 2006 .

[25]  Jian Cao,et al.  Investigation of Deformation Characteristics of Micropins Fabricated Using Microextrusion , 2005 .

[26]  Ulf Engel,et al.  Microforming of titanium – forming behaviour at elevated temperature , 2006 .

[27]  M. Fu,et al.  Study of size effect in micro-extrusion process of pure copper , 2011 .

[28]  Taylan Altan,et al.  An overall review of the tube hydroforming (THF) technology , 2001 .

[29]  Sang-Moon Hwang,et al.  Finite grain-element analysis and its experimental confirmation of micro-yoke forming , 2004 .

[30]  Gracious Ngaile,et al.  New Micro Tube Hydroforming System Based on Floating Die Assembly Concept , 2014 .