A Hybrid Incremental Sheet Forming Process for Fabricating Functional Surface Microtextures

Metallic components with large-area functional surface microtextures like microgrooves and dimples have special functions such as drag reduction and energy efficiency enhancement. Existing forming processes are not suitable for small batch production of functional surface microtextures over large areas due to the following disadvantages: low flexibility, time consuming and high production cost. Therefore, we proposed a hybrid incremental sheet forming process which combines the excellent flexibility of incremental sheet forming process with the characteristic of high forming quality of microgrooves in rolling process to manufacture both the macroscopic geometric shape and surface microtextures on curved metal components, simultaneously. An experimental platform for the hybrid incremental sheet forming process was firstly developed and curved microgroove arrays were successfully fabricated on the surface of AA2024-T6 sheet. Then, the effect of different press-in depth (h) and different step size (∆z) on the formation of microgrooves of the formed parts were investigated. It can be found that the depth of the fabricated microgrooves shows a nonlinear growth in relation to the press-in depth (h) due to the spring-back effect. Meanwhile, increasing the step size (∆z) is conducive to improving the formation of the microgroove. Furthermore, the surface roughness (Ra) and the surface morphology of the formed parts were analyzed. This work provides an effective approach to realize low-cost and high-quality processing of functional surface microtextures over large areas on metal sheets.