05 Asfm questions

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DOMANDE ASMF 2023-01-20 In tube hydroforming, generally, the internal pressure vs. time and the axial punch displacement vs. time loading curves are monotonously increasing. However, there are some exceptions listed below (select the CORRECT answers, multiple choice possible): o When the process is approaching calibration, i.e. when the tube is almost completely in contact to the die, there is no need to further increase axial feed while pressure is still increasing o If the material is perfectly plastic, i.e. it has no strain hardening, there is no need to increase pressure while the two axial punches provide axial compression o In short tubes with severe protrusion (as t- and y-shapes) pressure is increased only for the first half of the process, then nearly stopped and the protrusions are formed mainly by the action of the axial punches o During the forming phase of the process it might be useful sometimes to stop increasing pressure for a little while in order to facilitate pushing the material towards the bulge area with no increase of frictional resistance Sheet metal forming processes with a flexible tool can be implemented with either a fluid or a rubber tool. The “Guerin” and the “flexforming” processes have many similarities. Select the correct sentences among the following ones: o In both processes there is no independent blank-holding action and they are potentially capable of producing small undercuts o Both processes combine a solid die with a flexible punch o In both processes there is no concern for fluid leaking nor pinching of the rubber cushion o Both process can be implemented by means of single action hydraulic presses o In both processes a pre-bulging operation is useful to pre-stretch the sheet metal 2023-07-20 Which of the following sentences…