Paper Title
INVESTIGATION OF FRICTION CHARACTERISTICS IN PRESS FORMING OF HIGH TENSILE STRENGTH STEEL SHEET

Abstract
In this study, we investigated the displacement of the coefficient of friction between the material and the mold in order to improve the current poor analysis accuracy of the forming process in which the material flows into the mold. First, a new testing machine was fabricated to measure the coefficient of friction under high-speed and high-pressure conditions that simulate actual press forming. The test specimens were coated with press oil on both sides, attached to the chuck of the testing machine, and the surface pressure was adjusted to an appropriate level by tightening a bolt. The specimen was then pulled out by the servo press at an appropriate speed after confirming that the load cell signal was displayed on the monitor. The friction coefficient was derived using the holding load and the pull-out load obtained here. As a result, a surface pressure dependence was observed under all conditions of this experiment. This is thought to be due to the fact that the lubricant is trapped in the uneven surface of the material, resulting in a smaller coefficient of friction. In addition, velocity dependence was observed in some conditions. This is considered to be due to a change in the ease of lubricant flow caused by the difference in test time. Keywords - Friction Coefficient, High Tensile Steel Sheet, Lubrication Condition, Press Forming, Sliding Friction.