The article below shows the results of comparison between hydrostatic forming with constant blank holder force and changed blank holder force depending on stroke by experiment. Based on obtained results, it is possible to evaluate the influence of blank holder force on forming steps and product quality. | Journal of Science & Technology 122 (2017) 052-055 Research on the Influence of Varying Blank Holder Force on Product Quality in Sheet Hydrostatic Forming Nguyen Thi Thu, Nguyen Dac Trung Hanoi University of Science and Technology, No. 1, Dai Co Viet, Hai Ba Trung, Hanoi, Viet Nam Received: October 02, 2017; Accepted: November 03, 2017 Abstract Similar to conventional deep drawing, blank holder force in sheet hydrostatic forming plays an important role in avoiding instability on flange and creating good condition for forming of material into die cavity. Moreover, blank holder force also has an important function to tight material on flange in contact with die to prevent leakage of working fluid to lose high pressure of fluid in the chamber. Therefore, it is necessary to investigate the impact of blank holder force on other factors such as working pressure of fluid to achieve the best product quality. The article below shows the results of comparison between hydrostatic forming with constant blank holder force and changed blank holder force depending on stroke by experiment. Based on obtained results, it is possible to evaluate the influence of blank holder force on forming steps and product quality. Keywords: Hydrostatic forming, blank holder force, working pressure of liquid. 1. Introduction* his study on parameters in hydrostatic forming for a system of sphere part and pilar center. However, the difference of applying various graphs of blank holder force into hydrostatic forming has not been paid much attention. Blank holder force is an important factor because: it keeps workpiece stable during forming process, allows the workpiece to slide between die surface and holder to draw material into die cavity; besides, it contributes to resisting the leakage of high-pressure liquid. The blank holder force depends strongly on workpiece surface area. There is a fact that the flange area decreases when workpiece is drawn into die cavity, but the value of the blank .
