• 소성∙가공
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• 제15권9호
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• pp.660-666
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• 2006

This study examined the mechanical properties and bending formability evaluation of spring strip materials(SK5 CSPH, STS 301 CSP-EH, C7701-H). The hardness test and tensile test were performed at room temperature($20^{\circ}C$) for mechanical properties. The U-bending test were carried out at various conditions of punch corner radius(Rp), ratio of punch comer radius/thickness(Rp/t) and ratio of clearance/thickness(Rp/t) and ratio of clearance/thickness(C/t) for bending formability evaluation.

• 소성∙가공
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• 제17권8호
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• pp.586-593
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• 2008

In warm press forming of magnesium alloy sheet, it is important to control the sheet temperature by heating the sheet in closed die. When forming a commercial AZ31 magnesium alloy sheets which are 0.5mm and 1.0mm thick, respectively, time arriving at target temperature and temperature variation in magnesium alloy sheet have been investigated. The deep drawing process with rectangular shape alone at the first stage and with both circular and rectangular shapes at the second stage was employed. At the first stage, through deep drawing process with rectangular shape alone according to various forming temperature($150{\sim}350^{\circ}C$) and velocity($0.1{\sim}1.0mm/s$), optimum forming condition was obtained. At the second stage, deep drawing process with the circular and rectangular shapes were performed following deep drawn square cups with Limited Drawing Height(LDH) obtained at the first stage. Here, clearance which is defined a gap between the die and the punch including sheet was set to ratio of 20, 40 and 100% to thickness in sheet. Accordingly, temperature, velocities, and clearances suitable for forming were suggested through investigating the thickness variation of the product.