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이건엽(Lee Gun Yeop),최민규(Choi Min Kyu),박성필(Park Sung Pill),문영훈(Moon Young Hoon) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
Tube hydroforming is recently used in wide industrial fields as a metal forming prcess to substitute for the existing stamping process due to decrease of a general manufacturing process and cost-cutting. Parts having complex shapes sometimes require one or more pre-forming operations such as bending before the hydroforming process. At initial pre-bending stage, the variations of wall thickness and cross-section have effects on the accurracy of final products and quality. Because of a relatively excellent productive speed , geometric size precision and reliance of product qualities, rotary draw bending is widely used . This study shows the bendability in the various conditions of materials and process parameters with rotary draw bending FE Analysis.
이혜경(Hyae Kyung Yi),이건엽(Gun Yeop Lee),이성문(Sung Mun Lee),이영선(Young Seon Lee),문영훈(Young Hoon Moon) 대한기계학회 2008 大韓機械學會論文集A Vol.32 No.11
In this study, the characteristics of aluminum tube hydroformed products at different extrusion type and heat treatment conditions were investigated. For the investigation, as-extruded, full annealed and T6-treated Al 6061 tubes at different extrusion type were prepared. To evaluate the hydroformability, free bulge test was performed at room temperature to 300℃. Also mechanical properties of hydroformed products at various pre- and post-heat treatments were estimated by hexagonal prototype hydroforming test at 250℃. And the tensile test specimens were obtained from hexagonal prototype hydroformed tube. As a results, hydroformability of full annealed tube is 5~8% higher than that of extruded and T6-treated tube. The tensile strength and elongation of T6-post heat treated indirect extrusion tube were more than 330㎫ and 12%, respectively. However, T6 pre treated hydroformed product represents high strength, 330㎫ and low elongation, 8%. Therefore, Hydroformability of Al6061 tube showed similar value for both extrusion types. However flow stress of direct tube showed 20~50㎫ lower value than indirect tube.