An analytical FEM-based study of the drawing process of an ultra-high-pressure common-rail fuel tube

The strengthening of regulations on diesel-engine exhaust emission has demanded performance improvements, including those on the pressure-enhanced common-rail fuel-injection system. The common-rail fuel-injection tube must meet the extreme fatigue reliability requirements in this system to endure the pulsations caused by the high injection pressure and repeated injections, as well as vibrations from engine operation and vehicle driving. In this work, an analytical study was conducted to investigate the drawing process used to fabricate the common-rail ultra-high-pressure tube for application in the common-rail system with fuel injection pressures over 2200 bar. For the drawing-process analysis, the finite element method was used to compose the die, plug, and tube models critical to the drawing process of the fuel-injection tube. Results were further analyzed to determine the physical changes in the fuel-injection tube drawing process that occurred as a result of varying the die semi-angle and corresponding plug angle. Based on these analyses, a numerical analysis was performed to examine the effect of the die and plug on the fuel-injection tube drawing process. A tube drawing process solution was then obtained to ensure the optimum strength for the 2200 bar ultra-high-pressure common-rail fuel-injection tube.