Research on sheet-metal flexible-die forming using a magnetorheological fluid

• Published in: Journal of materials processing technology 2014-11, Vol.214 (11), p.2200-2211
• Main Authors: Wang, Zhong-jin, Wang, Peng-yi, Song, Hui
• Format: Article
• Language: English
• Subjects: Aluminum base alloys; Density; Formability; Forming; Magnetic fields; Magnetorheological fluids; Magnetorheological pressure forming (MRPF); Rheological properties; Sheet metal; Strain; Viscosity
• ISSN: 0924-0136
• DOI: 10.1016/j.jmatprotec.2014.04.016

•A new flexible-die forming method for sheet metal based on magnetorheological (MR) fluids, magnetorheological pressure forming (MRPF), is proposed.•Magnetorheological pressure bulging tests of Al1060 sheet under different conditions are conducted on the self-designed experimental apparatus.•Effect of MR fluid's rheological behavior under different magnetic fields, especially viscosity, on sheet's formability is evaluated. Related studies showed that viscosity has a great effect on the formability of sheet metal in viscous pressure forming. However, the viscosity of viscous medium keeps constant in VPF. In this paper, a new flexible-die forming method for sheet metal using magnetorheological (MR) fluids, magnetorheological pressure forming (MRPF), is proposed, which enables the viscosity of flexible-die medium adjustable by changing the magnetic fields during the forming process. Squeezing tests of MR fluid show that its rheological behavior can be changed greatly under different magnetic fields. Magnetorheological pressure bulging tests of Al1060 sheet are conducted on the self-designed experimental apparatus. Experimental results show that MR fluids can be used effectively as a flexible-die medium to form the parts and its rheological behavior can be adjusted during bulging process. Variation of MR fluid's rheological behavior can lead to different forming pressure load paths and have an effect on sheet metal formability. For the same piston stroke of 8.0mm, when the magnetic flux density is 0.180T and 0.318T, average dome height of bulging specimen is 8.71mm and 10.61mm, respectively. The value increases significantly by 21.8%. At the same time, the maximum thickness strain increases from −9.2% to −23.0%.