Incipient and repeatable plastic flow in incremental sheet-bulk forming of gears

Abstract

This paper analyses the differences between incipient and repeatable material flow in the incremental sheet-bulk metal forming (SBMF) of gears produced by indentation along the direction perpendicular to the sheet thickness. The underfilling of the punch cavity during the first indentation, which prevents the production of sound disk gears, is explained on the basis of constrained material flow under material strain hardening. A solution based on the utilization of a tailored disk blank is proposed to overcome this defect. The geometry of the tailored disk blank is determined by means of finite element analysis, and the overall methodology involved material characterization and experimentation with DC04 mild steel. The discussion on the extent of the plastic deformation region under constrained and free-material flow during indentation is complemented by experimental results obtained with a flat punch in rectangular sheet blanks of aluminium EN AW-1050A.

A New Successive Forming Process for Large Modulus Gears

“…The teeth are evenly distributed basically. The incremental SBMF of gears designed by Sieczkarek et al [21] was focused on evaluating the in uence of material sideway spread on the evolution of the load with displacement, so its blank holders were used to position the sheet but didn't impose constraints on the forming area of the edge of the blank, however, the ba es here are designed to prevent the widening of end faces. Due to the restriction of experimental conditions, the ba es are not thick enough to work effectively.…”

“…An incremental gear forming process by means of double-wedge gear tooth punch was provided [20]. Then, his group analyzed the differences between incipient and repeatable material ow in incremental SBMF of gears, and investigated three in uencing factors aiming for a form lling progress of the rst tooth element and an improvement of the teeth heights [21,22].…”

A non-invasive node-based form finding approach with discretization-independent target configuration

“…A challenge arises from the dependence of the spatial position of a design node on its target spatial position that restricts the final material position of the design node. This problem becomes obvious by comparing the optimal material configuration of a simulation of the notch stamping process, outlined in [6,12], for using two differently discretized target spatial configurations. The target configurations to which the respective optimization was aimed are depicted in Fig.…”

“…12 Experimental observed grain structure of a bended blank after upsetting with the detailed views of two cavity defects [2] the second stage of the forming process, the upsetting. During the upsetting the teeth are getting impressed into the deep-drawing ring to end up with the demonstrator displayed in Fig.…”

Sheet-bulk forming of three-dimensional features in metal and polymer blanks

“…The first step in this direction was given by Sieczkarek et al, 8 who proposed the fabrication of functional features in sheet metal parts by incremental compression in the direction perpendicular to thickness. The deformation mechanics of this process and its application to the fabrication of disk gears made from DC04 steel were subsequently investigated by Sieczkarek et al 9,10 This paper revisits the incremental sheet-bulk forming of metals by investigating material flow and force requirements in the indentation of rectangular and circular aluminum blanks by flat, curved, and gear tooth punches, and gives the first step towards the extension of sheet-bulk forming to polymers. The potential of producing polymer gears by incremental sheet-bulk forming is investigated and comparisons are made with gears fabricated in aluminum.…”