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We evaluated the texture distribution in the thickness direction of the spun workpieces and clarified the mechanism of the change in the crystal orientation of the texture during metal spinning. Blank aluminum disks with a thickness of 1.44 mm were deformed into circular truncated cone cups by under-, true shear, and over-spinning and into cylindrical cups by 13 passes of conventional spinning. Crystal orientation analysis using electron backscatter diffraction revealed that the calculations of the orientation densities for small Miller indices could lead to a systematic evaluation of high intensity texture. The orientation density of Cu {121}< 1 1 ¯ 1 > decreased or that of B {110}< 1 1 ¯ 2 > increased on the roller side of the shear-spun part, of the workpieces formed by shear spinning, and on the roller side of the wall part and on the mandrel side of the open-edge part, of the workpieces formed by conventional spinning. The cosine similarity and Euclidean distance showed that the texture distributions obtained by shear spinning and that of the wall part obtained by conventional spinning were similar. Based on the stress state and preferred crystal orientation in deep drawing, the mechanism of the change in crystal orientation during spinning were described. The density of the texture with {110} (corresponding to B in this study) parallel to a disk plane increased when tensile stress was applied in the circumferential direction, contrarily, when compressive stress was applied in a similar fashion the density of the texture with {112} (corresponding to Cu) parallel to the disk plane increased. [Display omitted] • Clarified the mechanism of change in crystal orientation during metal spinning. • Deriving orientation density of small Miller index systematically founds high intensity texture. • Cu density decreased or B density increased on roller side at wall and on mandrel side at open edge. • Quantitative technique evaluated similarity of textures between shear and conventional spinning. • Tensile stress in a circumferential direction decreased Cu density and increased B density. [ABSTRACT FROM AUTHOR]

Abstract: A flexible method of forming circumferentially variant wall thickness distributions on the same shape is attempted using two oblique sheet spinning processes. The fundamental strategy entails the inclination of the flange plane of the workpiece during forming. In one type of synchronous dieless spinning, edge-hemmed aluminum blanks are formed for truncated cone shells, by synchronizing the motion of the spherical head roller in the axial and radial directions with the angle of the general purpose mandrel fixed on a bidirectionally rotating spindle. On the other hand, in the other type of force-controlled shear spinning, flat aluminum discs are formed by feeding perpendicularly to the flange plane of the workpiece and maintaining the thrust force along the plane via the roller tool, exerted onto the rotating truncated-cone-shaped die. The estimated wall-thickness distribution based on a simple shear deformation model nearly conformed to the measured thickness distributions of the products formed at several inclination angles of up to 15 degrees in the forming and both spinning methods. The low-cost value-added forming method seems to be practicable not only for metal spinning but also for other incremental sheet forming processes. [Copyright &y& Elsevier]

Abstract: This review presents a thorough survey of academic work on the analysis and application of the mechanics of spinning. It surveys most literature published in English and the most important publications in German and Japanese languages. The review aims to provide insight into the mechanics of the process and act as a guide for researchers working on both metal spinning and other modern flexible forming processes. The review of existing work has revealed several gaps in current knowledge of spinning mechanics: the evolution of the stress state and the strain history of the workpiece in both conventional and shear spinning is not well understood, mainly due to the very long solution times that would occur in modelling the process throughout its duration with a sufficiently fine mesh to capture detailed behaviour through the workpiece thickness; the evolution of microstructure, residual stress and hence springback, has not been examined—either numerically or by experiment; the failure mechanisms of spinning – fracture and wrinkling – are only partially understood, through analogy with other processes, and as yet models of the process have not made use of contemporary damage mechanics; the design of toolpaths required to make particular parts without failure remains an art, and cannot currently be performed automatically with confidence. Studies on novel process configurations in spinning have shown that great potential for innovation in spinning exists. The process has the potential to be more flexible, to produce a wider range of shapes, and to form more challenging materials. [Copyright &y& Elsevier]

Abstract: The distribution of equivalent plastic strain through the thickness of several AISI 1020 steel plates formed under different conditions over a smooth cylindrical mandrel using a single-roller forward flow forming operation was studied by measuring the local micro-indentation hardness of the deformed material. The equivalent plastic strain was higher at the inner and outer surfaces and lowest at the center of the workpiece. Empirical expressions are presented which describe the contribution of the roller and mandrel to the total local equivalent plastic strain within the flow formed part. The dependence of these expressions upon the thickness reduction during flow forming is discussed. [Copyright &y& Elsevier]