Experimental investigation of friction coefficient in tube hydroforming
(1. Engineering Research Center for Net Shape and Die Manufacturing, School of Mechanical Engineering,
Pusan National University, Busan 609-735, Korea;
2. Technical Research laboratories, POSCO, Jeonnam 545-090, Korea)
Pusan National University, Busan 609-735, Korea;
2. Technical Research laboratories, POSCO, Jeonnam 545-090, Korea)
Abstract: The friction coefficient between tube and die in guide zone of tube hydroforming was obtained. In hydroforming, the tube is expanded by an internal pressure against the tool wall. By pushing the tube through tool, a friction force at the contact surface between the tube and the tool occurs. In guiding zone, the friction coefficients between tube and die can be estimated from the measured axial feeding forces. In expansion zone, the friction coefficients between tube and die can be evaluated from the measured geometries of expanded tubes and FE analysis.
Key words: tube hydroforming; friction coefficient; lubricant; axial force; internal pressure