Abstract
To enhance stability during the forming process and improve the quality of the product, it is essential to analyze and identify the influence of the process parameters on the sheet formability. Therefore, this research investigates the influence of key process parameters, including the forming fluid pressure and the blank holding force, on the formability to produce square cup parts using an AISI 1006 STEEL alloy sheet employing hydrostatic formation technology. The formability evaluation was based on two criteria: the maximum thinning in the formed parts and the minimum achievable corner radius. For this purpose, the authors manufactured an experimental setup for hydrostatic forming and verified this setup’s capability to manufacture square cups with specific dimensions. This setup provides and controls the three process pressures (forming, holding, and closing) independently, allowing greater flexibility to maintain process stability. In this regard, a process window with optimum peak fluid pressure and holding force combinations was determined. The experimental results indicated that these combinations allow for the successful formation of cups up to the entire die depth without encountering failures (wrinkling and fracture). Additionally, increasing the peak pressures for forming and holding within the process window reduced the achievable minimum corner radius, thereby enhancing dimensional accuracy. Simultaneously, it contributed to increasing the maximum percentage of thinning at the bottom corners. In particular, the thinning measurement was 23%, near the critical limit. Therefore, this process window helps select the optimal peak pressures based on the desired corner radius and the maximum allowable thinning for a given component.
Keywords
Formability
Hydrostatic formation
Process parameters
Process window
sheet metal forming