Local forming of gears by indentation of sheets

Abstract

The aim and objectives of this article are to provide an analytical model for the incremental forming of gears along the direction perpendicular to the sheet thickness. The model allows determining the influence of the major process parameters in the indentation force and in the material volume undergoing plastic deformation during indentation by means of double-wedge gear tooth punches. Special emphasis is placed on the influence of superimposing tension stresses along the in-plane direction. The analytical model is built upon the slip-line theory under plane strain deformation conditions, and results are compared against those obtained from experiments in DC04 mild steel and from numerical simulations performed with the finite element method. Results show that the indentation force can be significantly reduced by stress superposition, and that a minimum distance from previous indentations is necessary to produce a new gear tooth in a material free from residual strains and stresses.

A New Successive Forming Process for Large Modulus Gears

“…Compared with the double-wedge gear tooth punch designed by Sieczkarek et al [20], the single-tooth preforming die will put less constraints on the deformation area. At the same time, however, the forming accuracy of single-tooth die is lower than the double-wedge one, requiring multiple passes to be nished.…”

“…Sieczkarek et al [19] characterized the plastic ow and proposed a closed-form analytical framework to estimate the through-thickness pressure and force in sheet-bulk indentation. 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].…”

Flexibility in metal forming

“…27. Various types of tools can be utilized in the sheet-bulk metal forming process as shown in Fig. 27 [183]. Through the continuous and discontinuous forming process, flexible geometries can be manufactured.…”

“…29b). By processing the sheet edge, form-elements are aspired, such as gears [182]. With the forming operations on the sheet plane a locally defined material pile-up is formed which can be used as additional volume for fastening elements or as secondary design elements [205].…”

“…For the fundamental process understanding of the innovative iSBMF processes, analytical frameworks were developed to offer a physical insight at the deformation mechanics and to estimate the influence of the main process parameters on the force requirements [182,205]. Challenges during the incremental gear forming regarding a high tool wear and an insufficient form filling of the first gear element formed were faced and solved [205].…”