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Shear spinning is a bulk forming technique used to produce hollow, rotationally symmetric parts. Although the shear spinning process has been used for the last six decades in numerous industries, in the literature, the understanding of the mechanics of the process is limited. This study provides insight into process mechanics using physical trials and numerical models. Modelling the process is challenging because of the incremental nature of the process; existing numerical models in the literature suffer from lengthy computational times and simplifications. In this study, two numerical models with different approaches to the kinematics of the spinning process are modelled with input from tests to determine friction coefficient and material properties. Then they are validated against physical trials by comparing both part geometry and strain distribution. Validated numerical models are then employed to investigate the fundamental aspects of shear spinning mechanics; evolution of strains, roller forces and part geometry in a broad range of process conditions. [ABSTRACT FROM AUTHOR]

In this study, the effect of alteration in the direction of forming during the shear spinning of C11000 copper metal on mechanical properties, microstructure, texture, and anisotropy was investigated. Shear spinning causes the grains stretching along the axial direction besides increasing the grain length in the circumferential direction. Strain-path change in the shear spinning specimens has somewhat resulted in finer grains, more grain refinement, and a higher percentage of high-angle boundaries. More change of strain direction in the shear spinning specimens resulted in approximately 9% to 11% reduction in strength, from 1% to 9% decrease in hardness, and increased elongation from 7% to 37% more than in the specimen without path change. Shear spinning specimens in different paths had different orientations and texture intensities. In the specimen without strain-path change, most of the texture is related to {123}〈412〉 orientation and copper texture with {112}〈111〉 orientation. In the shear spinning specimens in other paths, textures with {001}〈100〉, {011}〈011〉, and {211}〈011〉 orientations and brass texture with {110}〈112〉 orientation were strengthened. Due to the change in texture and mechanical properties, the strain-path change in the shear spinning process reduced the anisotropy in the C11000 copper metal.

Internally-spline sleeves have an increased attention since these parts serve as power transmission means in many industrial applications. This research presents using ball spinning process for producing internally-spline sleeves. The process was investigated experimentally and theoretically. The experimentally investigated variables were: the rotational speed of the mandrel 86, 604, 1146 and 1747 rpm; the axial feed, 0.3, 0.6, 0.91 and 1.21 mm/ rev; the cross in-feed 1.5, 2, 2.5, 3 and 3.5 mm. An analytical expression was derived to predict the deformation loads. The theoretically investigated variables were: the mentioned axial feed and cross in-feed at 604 mandrel rotational speed; the initial tube thickness of 3.5 to 8 mm with step 0.5 mm; the ball diameters of 16 to 32 mm with step 4 mm; the number of ribs was 4, 5, 6, 8, and 10. The effects of these variables on the forming load and the quality of formed sleeves were investigated. The results showed that, these variables affecting the forming load and product quality. The optimum values of these variables were determined. The theoretical results have been found to be in close agreement with experiment. [ABSTRACT FROM AUTHOR]

A new mandrel-free hot-spinning was developed as a new near-net-shape forming technology. Hot-spinning provides a high flexibility, because of no mandrel. This paper investigated the material properties and dimensional accuracy of mandrel-free hot-spun Ti-6Al-4V alloy conical product with a wall angle of 30°at 900°C. It was found that the deformation in the process roughly followed the sine law. It is confirmed that shape control is possible by adjusting the roller path. Product thickness tended to be thicker than the thickness predicted by the sine law and the flange part is tilted in the direction of forming progress when the initial thickness was large. It is presumed that a certain amount of bending deformation takes place in the process and strain distribution in the thickness direction was caused during forming. For the purpose of improving forming accuracy in the mandrel-free hot-spinning, reducing the strain distribution in the thickness direction, including optimization of the temperature distribution in the thickness, and optimization of the roller feed ratio, may be most effective factors. [ABSTRACT FROM AUTHOR]

In order to shorten the preparation period, dieless shear spinning is widely used in various industrial fields with advantage of economy of materials and easy control. Controlling roller path is one of the main methods for changing thickness distribution. A new discretization method is proposed by theoretical derivation in dieless shear spinning. It will generate a virtual axis by inclining the flange of the workpiece. And, the roller path is derived for spinning machine combined with the sine law in shear spinning. The derived path should be applied after the range of forming reaches the certain height. The thickness distribution of formed workpiece is basically in agreement with the theoretical value. It also illustrates that roller nose radius and axial feed will influence the surface quality. [ABSTRACT FROM AUTHOR]

Three commercial Al-Mg alloys containing 3 wt.% to 6 wt.% of Mg (AlMg3, AlMg4.5Mn and AlMg6Mn) were subjected to different forming processes: shear spinning and cold rolling. The effect of Mg content and reduction in thickness on the tensile properties and microstructure evolution of Al-Mg alloys were studied. Both optical (OM) and transmission electron microscopy (TEM) were used for the microstructure characterization. The results show that the addition of Mg in these alloys increases the yield strength (YS) and ultimate tensile strength (UTS) in both cold rolled and spun specimens. The strength of all Al-Mg alloys after shear spinning was lower compared to the strength after cold rolling for the same strain. This effect was attributed to the occurrence of dynamic recovery during shear spinning and confirmed by transmission electron microscopy. [Projekat Ministarstva nauke Republike Srbije, br. TR-34018]

To investigate the grain refinement and its mechanism in shear spinning, microstructures of shear spun parts made by aluminium alloy under different deformation conditions, induced by different shear spinning deviation ratios, are studied. The results show that, after shear spinning, the microstructure is distributed symmetrically about a zone in sheet thickness defined as the neutral zone which is located between the inner surface and the middle plane of spun sheet thickness. Various deviation ratios in shear spinning can lead to grain refinement in different regions along thickness direction of the spun part. The microstructure characteristics indicate that the mechanism of grain refinement is due to the formation of deformation bands (DBs). It is observed that in DBs, parallel geometrically necessary boundaries (GNBs) formed by a zero deviation ratio and crossed GNBs formed by positive and negative deviation ratios are due to the different stress states induced by various deviation ratios in shear spinning. Due to the influence of grain refinement, micro hardness increases with the decreasing of the deviation ratio. The average value is increased by 16.04% under a negative deviation ratio compared to the initial micro hardness of the sheet. [ABSTRACT FROM AUTHOR]

This paper presents the implementation of an external axis control system on a conventional CNC machine so that the machine can be actively controlled in response to sensors such as vision and force. The controller that runs on an external computer has direct access to the CNC controller for machine position sensing. The control signals to the machine are sent through purpose built circuitry via the machine's manual pulse generator (MPG) inputs. To demonstrate the accuracy and performance of the control system, it was used to visually track the profile of a mandrel used for shear spinning. The implemented system eliminates the parallax error and the need to use an accurate pixel resolution. The raw tracking data is processed by a curvature detection algorithm that detects linear and circular segments and segment transitions. The results show that the visual tracking system provides accurate tracking results that are well within the tolerances used in the industry.

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]

The effects of feeding ratio on flange bending of shear spinning are investigated with analytical method. Firstly, influence of feeding ratio on total energy is analyzed utilizing the formula of shear spinning force and power derived by energy method. Subsequently, the connection between the deviation ratio and the thinning ratio, and the influence of feeding ratio on the thinning ratio are researched. Finally, the conclusions about the deviation ratio and flange bending are adopted to reveal the influential tendency of feeding ratio on flange bending. The results show that the flange bending towards headstock weakens with the increase of feeding ratio, which is verified by the experimental results very well. It indicates that the calculation method in this paper is reasonable. [ABSTRACT FROM AUTHOR]

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 deformation mechanism of incremental sheet forming (ISF) is examined experimentally through forming specially prepared copper sheets. Strain distributions through the thickness of the sheets are measured for two configurations of ISF: two-point incremental forming (TPIF) and single-point incremental forming (SPIF), and a comparison is made to pressing. The measurements show that the deformation mechanisms of both SPIF and TPIF are stretching and shear in the plane perpendicular to the tool direction, with shear in the plane parallel to the tool direction. Strain components increase on successive laps, and the most significant component of strain is shear parallel to the tool direction. Increasing stretching and shear perpendicular to the tool direction account for differences between the sine law prediction and measured wall thickness for both SPIF and TPIF. The observed mechanisms of SPIF and TPIF differ from a mechanism of pure shear that has previously been assumed. [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]

Abstract: An experimental study is conducted to survey the technological possibility of the shear spinning of truncated hemispherical shells with a cylindrical mandrel for general purposes using A1050-H and A1050-O commercially pure aluminum sheets of 1mm thickness. It is found that there exist forming limits to prevent the occurrence of wall fractures and flange wrinkles during the spinning process of truncated hemispherical shells. It is also found that the sine law is not realized exactly in shear spinning of truncated hemispherical shells with a cylindrical mandrel for general purposes due to the spring back of the workpiece. [Copyright &y& Elsevier]

The shear spinning process, where the plastic deformation zone is localized in a very small portion of the workpiece, shows a promise for increasingly broader application to the production of axially symmetric parts. In this paper, the three components of working force are calculated by the newly proposed deformation model in which the spinning process is understood as shearing deformation after uniaxial yielding by bending, and shear stress, τ rz becomes k, yield limit in pure shear, in the deformation zone. The tangential forces are first calculated and the feed forces and the normal forces are obtained by the assumption of uniform distribution of roller pressure on the contact surface. The optimum contact area is obtained by minimizing the bending energy required to get the assumed deformation of the blank. The calculated forces are compared with experimental results. A comparison shows that theoretical prediction is reasonably in good agreement with experimental results. [ABSTRACT FROM AUTHOR]

Abstract: An analytic model for calculation of shear spinning force incorporate factor of over-roll (press down) of the blank is derived. The effects of blank thickness, roller nose radius, mandrel revolution and roller feed on the spinning force are discussed. Results obtained from calculation were compared with the experiment and other theoretical predictions. It is found that the present findings yield optimum results. [Copyright &y& Elsevier]

A high quality of cone surface finish was achieved by carefully controlled over-roll thickness in the shear spinning process. In this study, blank thickness, roller nose radius, mandrel revolution, roller feed and over-roll thickness were taken as major process variables to investigate the effects of the above parameters on the surface roughness of cone shape products. From the experiment, several sets of experimental data were obtained, which in turn were used to construct regression equations for applied forces and product surface roughness. The results were verified by four extra spinning experiments. It is found that deeper over-roll combines with the thinner blank sheet, larger roller nose radius and slower roller feed, and are advantageous for obtaining smoother surface roughness. Over-roll of the blank in shear spinning is an effective way to improve the surface roughness of the product. [Copyright &y& Elsevier]

The shear spinning process, where the plastic deformation zone is localized in a very small portion of the work piece, is introduced for the manufacturing of large conical shapes. This process seemingly shows a promise for increasingly broader application to the production of axially symmetric parts. This study is to gain a better understanding of the process of shear spinning and to propose a lower upper-bound solution for shear spinning cones. Velocity fields and strain rates are derived from considering the adequate deformation mode and the contact factor is introduced to obtain the lower upper-bound power. The theoretical values are compared with the experimental results of various materials. Al-1100-0, Al-1100-H14, and Al-6061-0. A comparison shows that theoretical prediction is reasonably in good agreement with experimental results. [Copyright &y& Elsevier]

Polymeric scaffolds comprising two size scales of microfibers and submicron fibers can better support three‐dimensional (3D) cell growth in tissue engineering, making them an important class of healthcare material. However, a major manufacturing barrier hampers their translation into wider practical use: scalability. Traditional production of two‐scale scaffolds by electrospinning is slow and costly. For day‐to‐day cell cultures, the scaffolds need to be affordable, made in high yield to drive down cost. Combining expertise from academia and industry from the United Kingdom and United States, this study uses a new series of high‐yield, low‐cost scaffolds made by shear spinning for tissue engineering. The scaffolds comprise interwoven submicron fibers and microfibers throughout as observed under scanning electron microscopy and demonstrate good capability to support cell culturing for tumor modeling. Three model human cancer cell lines (HEK293, A549 and MCF‐7) with stable expression of GFP were cultured in the scaffolds and found to exhibit efficient cell attachment and sustained 3D growth and proliferation for 30 days. Cryosection and multiphoton fluorescence microscopy confirmed the formation of compact 3D cell clusters throughout the scaffolds. In addition, comparative growth curves of 2D and 3D cultures show significant cell‐type‐dependent differences. This work applies high‐yield shear‐spun scaffolds in mammalian tissue engineering and brings practical, affordable applications of multiscale scaffolds closer to reality. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2750, 2019. [ABSTRACT FROM AUTHOR]