Hybrid Manufacturing of Stiffening Grooves in Additive Deposited Thin Parts

Valentino A M Cristino,João P M Pragana,Paulo A F Martins,Carlos M A Silva,Ivo M F Bragança

doi:10.3390/jmmp5040140

Valentino A M Cristino, João P M Pragana + Show 3 more

Open Access

https://doi.org/10.3390/jmmp5040140

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Abstract

This paper is focused on the hybridization of additive manufacturing with single-point incremental forming to produce stiffening grooves in thin metal parts. An analytical model built upon in-plane stretching of a membrane is provided to determine the tool force as a function of the required groove depth and to estimate the maximum allowable groove depth that can be formed without tearing. The results for additively deposited stainless-steel sheets show that the proposed analytical model can replicate incremental plastic deformation of the stiffening grooves in good agreement with experimental observations and measurements. Anisotropy and lower formability caused by the dendritic-based microstructure of the additively deposited stainless-steel sheets justifies the reason why the maximum allowable depth of the stiffening grooves is approximately 27% smaller than that obtained for the wrought commercial sheets of the same material that are used for comparison purposes.

Highlights

Stretching is a metal forming process in which an initially flat sheet, gripped along its edges, is stretched and bent simultaneously with the intention of obtaining a contoured panel by enlargement of the surface and reduction of thickness (Figure 1a)
Recent developments by Köhler et al [2], who proposed a cam-actuated mechanism to provide lateral support of stringers during forming of the panels, show potential to make the inverse approach feasible even though the suppression of buckling may lead to new failure modes, higher amounts of spring back after forming and increased tooling costs when compared with the conventional stretching and strengthening approach
It makes sense to investigate the possibility of implementing a new hybrid metal additive manufacturing approach [11] that combines additive manufacturing and in-plane stretching by SPIF to produce local, customized, stiff

Summary

Introduction

Stretching is a metal forming process in which an initially flat sheet, gripped along its edges, is stretched and bent simultaneously with the intention of obtaining a contoured panel by enlargement of the surface and reduction of thickness (Figure 1a). Is different from the classical (narrow) definition in which two or more processes factured parts, which require the use of support structures whenever complex out-ofare combined in situ at the time and has been previously utilized in a process plane-shaped features are to be included to preserve the overall geometric integrity of the sequence parts, and prevent the occurrence of defects and failures, such as deformations, dross formation or warpage [10] In such cases, it makes sense to investigate the possibility of implementing a new hybrid metal additive manufacturing approach [11] that combines additive manufacturing and in-plane stretching by SPIF to produce local, customized, stiff-. Anisotropy justify the differences in the mechanical response the additively depositedof and wrought wrought commercial stainless-steel sheets, in agreement withofprevious observations commercial stainless-steel in agreement previous observations the authors in the same material [14] andsheets, of other authors in with different materials [15]. of the authors in the same material [14] and of other authors in different materials [15]

Additively

Single-Point Incremental Forming of the Stiffening Grooves

Tool Force

Strain Paths

Influence