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Abstract: Ever increasing demands on functional integration of high strength light weight products leads to the development of a new class of manufacturing processes. The application of bulk forming processes to sheet or plate semi-finished products, sometimes in combination with conventional sheet forming processes creates new products with the requested properties. The paper defines this new class of sheet-bulk metal forming processes, gives an overview of the existing processes belonging to this class, highlights the tooling aspects as well as the resulting product properties and presents a short summary of the relevant work that has been done towards modeling and simulation. [Copyright &y& Elsevier]

Abstract: Existing tests for assessing the formability of sheet metal samples can create strain ratios in the range from uniaxial to biaxial stretching, −1/2≤ ɛ 2/ɛ 1 ≤1. A novel sample design is proposed, with shaped cut-outs in a rectangular sheet specimen, intended to produce with strain ratios in the range, −1≤ ɛ 2/ɛ 1 ≤1/2 in a small zone, while the sample is uniaxially extended. The strain ratio is controlled by changing the geometry of the cut-outs. The behaviour of the new sample design is examined by finite element modelling showing nearly proportional behaviour in the test zone, with the best results occurring near to pure shear. Two experimental methods are considered for the validation of these predictions: measurement of the distortion of a grid of small circles created on the sample surface by laser-scribing; use of a commercial strain measurement system based on an applied speckle pattern. Both techniques demonstrate that the evolution of experimentally measured strains during the test closely follows that predicted numerically. The novel sample is applied to test the formability of a range of materials known to be difficult to form. The tests on aluminium alloys Al 2024, Al 7075, Al 2198 and commercially pure titanium demonstrate that significantly enhanced deformation prior to failure is possible with loading near to pure shear. The implication of these results is that it may be possible to design novel forming processes capable of creating more dramatic deformation in “difficult to form” materials through the creation of strain paths close to pure shear. [Copyright &y& Elsevier]

Abstract: A novel class of ‘paddle forming’ processes for forming pronounced features within sheet metal components is presented. The processes are incremental in nature and are characterised by having contact between the tool and the workpiece along a short line segment. The processes lead to high through-thickness shear strains, which have been shown to increase the possible deformation before ductile instability occurs. Paddle forming tools, which are cheap and simple to manufacture, can be applied to the faces or edges of sheets, tubes and disks. Four example processes are demonstrated, each showing high deformation and pronounced through-thickness shear strain. [Copyright &y& Elsevier]