The high-pressure liquid jet incremental forming for the aluminum sheet

Abstract

High-pressure liquid jet incremental forming, a new die-less forming process, utilizes liquid as a flexible tool to deform the sheet metal. In this article, an oil was used as the forming liquid. Theoretical analysis and numerical simulation were conducted to obtain the influence of jet nozzle geometry on the jetting pressure and velocity, and then, the best conic angle of the nozzle was proven to be 13°. Through analyzing the simulation results, it is found that the preferable jetting distance is between 15 and 30 mm and the dynamic pressure distribution approximately obeys a Gaussian distribution on the cross section of the oil jet. Aluminum sheets with a thickness of 0.3 mm were used in the local bulging experiment and simulation to investigate the process parameters of high-pressure oil jet forming. High-pressure liquid jet incremental forming is one of several high-speed forming methods. To obtain the precise simulation results, the dynamic effect of jetting pressure was studied by using Abaqus/Explicit. The results show that using loading time 0.02 s in the simulation is suitable for the simulation of the dynamic effect caused by the high-pressure oil jet. By comparing the deformation of the sheet under different oil pressures, it can be found that the deformation of the aluminum sheet becomes severe as the oil pressure increases, and the proper oil pressure is 15 MPa for the 0.3-mm-thick LF21 aluminum sheet. To investigate the influence of jetting path on the surface quality of the sheet metal parts, the forming processes of the 0.3-mm-thick LF21 aluminum sheets, with different path intervals, were simulated. The simulation results show that a better forming quality of the workpiece can be obtained when the jetting path interval is 4 mm.