Experimental Analysis the Effect of Lubricant and Ultrasonic Excitation of Hemispherical-head Tool on the Vertical Component of Forming Force in SPIF

Aluminum alloys have been widely used in various industries, due to its special characteristics. On the other hand, due to its low formability, the forming of these alloys is difficult at room temperature. Therefore, in order to facilitate the forming, warm forming methods can be used, which will lead to the oxidation of the material. In Single Point Incremental Forming (SPIF), a sheet metal is formed by a progression of localized plastic deformation using a hemispherical-head tool. In this study, by applying ultrasonic vibration to the tool, Ultrasonic Vibration assisted SPIF (UVaSPIF) process was developed that improved the sheet formability at room temperature. In present paper, the effect of ultrasonic vibration and lubricant on behavior of the forming force has been investigated. Consequently, a hemispherical-head tool (D = 20 mm) with natural frequency of 20.4 kHz was designed and manufactured. The occurrence of longitudinal mode and resonance phenomenon has been confirmed by the results of modal analysis and experimental test. Then, Al 1050-O sheet was used as a work material. Experimental results obtained from straight groove test, indicate that in UVaSPIF, imposing of vibration without lubricant has the greatest impact on reducing the vertical component of the forming force whereas in SPIF, the lubricant has the greatest impact on reducing the vertical component of the forming force.