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The metal spinning process has been observed in recent major investigations carried out using finite element analysis. One interesting idea has proposed simulating a rotating disc for the simulation of the metal spinning process to reduce computational time. The development of this concept is presented in this paper, including the formal mathematical transformation from the inertial frame to the rotating reference frame, specific FEM configurations with mesh sizes based on a minimized aspect ratio, a mesh convergence study, and the application of a feed rate scale. Furthermore, in the context of the rotating reference frame, the flange geometry after wrinkle initiation is investigated, including the number of peaks and their amplitudes. Using this new approach, it was found that the number of peaks gradually increases from two to eight peaks while their amplitude decreases. In the case of severe wrinkles, the number of peaks stays at four while the amplitude increases dramatically. The intermediate path proves capable of increasing the number of peaks while maintaining a low amplitude. These results will make it possible to design new paths, facilitating the production of defect-free spun parts. [ABSTRACT FROM AUTHOR]

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Now, metal spinning is no longer limited to axisymmetric parts. Die-less spinning for non-circular section parts is on the rise for its advantages of low cost and high flexibility. However, the wall thickness decreasing has always been the problem of die-less spinning. In view of this, the ball-crown-shape roller is adopted to form the square section cone without die. The calculation method of roller path based on the ball-crown-shape roller is proposed and carried out by a 5-axis CNC spinning machine. Meanwhile, the finite element model is established to analyze the stress and strain states during spinning. According to the results of the experiment and simulation, the wall thickness of the parts is barely reduced for the sheet under the radial compressive stress as well as circumferential compressive stress. The wall angle of the experimental part is greater than the designed cone angle. The reason for the flange wrinkling is analyzed, and some preventive measures are put forward accordingly. [ABSTRACT FROM AUTHOR]

Many equipment and devices utilized in the aerospace industry are formed as symmetric parts through high plastic deformation of high strength sheet metal alloys with low thickness. Considering the inherent advantages of the spinning process of simple tooling and concentrated deformation loading, this process can be considered as one of the main options in producing these thin-sectioned lightweight parts. In this study, a Finite Element (FE) model has been developed to simulate the formation of a stepped thin-walled cylindrical workpiece of AISI 316 stainless steel alloy by spinning process. The FE simulation results were employed to investigate the effects of process parameters, including feed rate of the roller and rotational velocity of the mandrel on the distribution of stress and strain in the sheet metal, wrinkling failure, and thinning of the sheet metal during deformation. Experiments were carried out using selective input parameters based on the results of FE simulations. The comparison between FE simulations and experiments revealed that the developed model could predict the thinning of the sheet metals with over 93 % accuracy. Additionally, a good agreement between the experimentally deformed sheet configurations with those resulting from finite element simulations has been observed.    [ABSTRACT FROM AUTHOR]

Metal spinning process is widely used because of its low power requirement to producing complex symmetry components. Spinning process parameters influence the spinning force and wall breakage or wrinkling problems of finished parts. The experimental and numerical simulation of metal sheet spinning has been applied to investigate the effect of spinning process parameters in order to achieved lower force and large deformation without the wall breakage or wrinkling failure. In the study, Taguchi method is implemented in cooperate with finite element analysis to reduce the number of numerical simulation. The spinning experiments were carried out on a modified turning lathe to accommodate a Kreisler force transducer to measure spinning forces. The three dimensional finite element model of sheet metal spinning was developed using the same spinning experiment process parameters. The SPCC sheet metal workpiece is modelled as an isotropic elastic-plastic material. The average predicted spinning force was 853 N. There is an error of 6.25% in the FE model prediction. Furthermore, the predicted thicknesses of the deformed part were compared with the measured experimental parts thickness and the error was 6.06%. It is clear that the finite element model results agreed well with the spinning experimental results. The effect of eight process parameters, i.e. roller radius, spindle speed, feed rate and feed depth, friction coefficient, width of support roller, diameter of support roller and angel of mandrel slope, on spinning force and deformation were studied. Finite element analysis of Taguchi-L18 spinning experiment were carried out. Taguchi main effect analysis and ANOVA results show that the slope of mandrel, spinning depth and support roller width are the most important factors influencing the spinning force. The slopes of mandrel, spinning depth and roller radius are the most important factors influencing the thickness variation of deformed parts. The roller radius, spinning depth and support roller width are the most important factors influencing the severity of wrinkling failure. [ABSTRACT FROM AUTHOR]

Profiled power spinning is a complex metal forming process as there are many factors interrelated. The spinnability plays an important role in predicting fracture and controlling the shape of the profiled component. In this paper, a 3D finite element (FE) model is established so as to investigate on the spinnability of the ellipsoidal power spinning. The variation of the equivalent stress and the equivalent plastic strain are analyzed, and the analysis of variance takes comprehensive influence on the spinnability into consideration. The fracture behaviors of the ellipsoidal components are analyzed with the Johnson-Cook fracture criterion. The results show that the equivalent stress and the equivalent plastic strain increase with the forming time. As for the mono-factor influence, the spinnability is improved when the feed rate of the rollers decreases or the friction coefficient increases. As for the multi-factor influence, the interaction between the feed rate and the friction coefficient has a significant effect on the spinnability. The initial fracture is presented in the fillet part between the blank and the mandrel where the equivalent plastic strain reaches the maximum, the stress triaxiality is the minimum, and the Johnson-Cook damage initiation criterion approach one. The simulation results using the Johnson-Cook fracture criterion are in a good agreement with the experimental results during the ellipsoidal power spinning. [ABSTRACT FROM AUTHOR]

The influence of spinning methods and the distributions of equivalent strains on grain refinement were studied to realize the overall grain refinement along the thickness direction of the cylindrical parts manufactured by spin-forming. The metal flow model of counter-roller spinning was established based on upper bound method and compared with that of the stagger spinning; the processes of the stagger and the counter-roller spinning were simulated based on the commercial FEA software, MSC.Marc. The results show that the distribution of equivalent strains of spun part obtained by counter-roller spinning is more homogeneous than that of stagger spinning; the simulation results of the equivalent strains of the counter-roller spinning conform well to the theoretical calculation results, and the relative deviations between the calculation and simulation results are less than 10 %. The corresponding metallographic analysis was further carried out to verify the theoretical analysis. The results indicate that the percentage of grain refinement on inner layer is far less than that of the outer layer during stagger spinning, whereas the percentage of grain refinement on the inner and outer layers of the spun parts are nearly the same during counter-roller spinning. [ABSTRACT FROM AUTHOR]

An investigation into material wrinkling failure mechanics of conventional metal spinning and the effects of process parameters and material properties are presented in this paper. By developing finite element (FE) models using the Box-Behnken design of experiments, the effects of six key process and material parameters on the start of material wrinkling have been investigated. These key factors include roller feed per pass, feed rate, blank thickness, tool path profile, material Young's modulus, yield stress and strain hardening exponent. The results of FE simulation are validated by comparing the modelled roller tool forces and spun part end shape with those measured during a spinning experiment. From FE simulations, large residual stresses in the form of bending moments are found to be present in the flange of the blank, induced by the roller contact. It is found that material wrinkling failure begins when a plastic hinge is formed between the roller and the edge of the blank. It is found that both roller feed per pass and feed rate produce the most significant effect on the initiation of wrinkling failure, as they increase the bending stresses causing a plastic hinge to form more rapidly, thus wrinkling to occur more quickly. [ABSTRACT FROM AUTHOR]

Wrinkling failure mechanics of conventional metal spinning is investigated by means of finite element (FE) simulation. The results of FE simulation are validated by comparing the modelled roller force with that measured during a spinning experiment. From FE simulation, large residual stresses in the form of bending moments are found to be present in the flange, induced by the roller contact. It is found that wrinkling failure begins when a plastic hinge is formed between the roller and the edge of the blank. These bending moments cause the wrinkled state of the flange to be energetically favourable, which is seen as a reduction in the magnitude of these moments and the elastic strain energy of the FE model at the point of wrinkling. [ABSTRACT FROM AUTHOR]

Conventional spinning is a widely used metal forming process to manufacture rotationally axis-symmetric and asymmetric products. Considerable efforts have been made to investigate the forming quality of spun parts using the process in recent years. However, inherent uncertainty properties involved in the spinning process are rarely considered in previous studies. In this paper, an uncertainty analysis and process optimisation procedure have been developed and implemented on conventional spinning with 3D Finite Element Method (FEM). Three process variables are randomized by Gaussian distribution to study the probabilistic characteristics of two process responses. Linear and quadratic approximate representations are constructed by Monte Carlo based Response Surface Method (RSM) with Latin Hypercube Sampling (LHS). The Most Probable Point (MPP) method, which has been widely used to estimate the failure probability in other applications, is further developed in this paper to obtain the probability distribution of the system responses. Following an evaluation of the system responses conducted by the MPP method, a control variable method is used to reduce the variance of spun part wall thickness and total roller force to satisfy the 3 σ quality requirement. This uncertainty analysis and process optimisation procedure can be easily implemented in other metal spinning processes. [ABSTRACT FROM AUTHOR]

One of the old forming processes in which there is ability to produce empty parts with central symmetrical axis under acting of local and circular force is called spinning process. In cases that there is no possibility to use the process of deep drawing due to size or complex structure, spinning is a good substitute process. In metal forming processes such as spinning, temperature is one of the important parameters which must be investigated. Regarding investigation of thermo-mechanical simultaneous spinning process, no work has been done to date while some studies have been done on mechanical analysis of spinning process. In this study, the finite element method and an experimental test are used for simulation and validation of spinning process parameters for aluminum sheet. The simulation is used for two different shapes such as hemisphere and semi-conic. By comparison of numerical and experimental results it is observed that these results have suitable convergence. [ABSTRACT FROM AUTHOR]

This work analyses the structural integrality for a large aspect ratio dual thrust solid rocket motor (SRM) grain of one antiaircraft missile. Various loading conditions were analyzed during spinning launching process. Based on 3D viscoelastic FEM method, the stress-strain fields were simulated. Results show that the interior pressure loads, axial inertial loads and angular acceleration loads are the primary loading factors that influence its structural integrity. The rear face of grain boss is the dangerous place and the excessive stretch of the cantilever section would lead to gas channel's congestion, which might cause the interior pressure drastic-increasing even failure of shell. It is suggested that the following measures be effective to optimize the structure of solid rocket motor, such as improving the charging tooling to avoid micro-crack, setting the fixtures or supporting mechanism to cantilever section and optimizing the ratio of burning surface to port area ratio. [ABSTRACT FROM AUTHOR]

Abstract: Tube spinning is a commonly used process for manufacturing axisymmetric parts in automotive and aerospace industries and a method for fabricating pressure vessels. Generally the studies of tube spinning process have been limited to thin wall tubes and the FE (Finite Element) simulations have usually incorporated shell elements (incapable of proper investigation of strain diversity in thickness). Therefore, the material deformation in thickness has not been properly investigated. In this paper, spinning for manufacturing a dome form on tube end is analyzed using an enhanced explicit 3-D finite element model, supported by an experiment. Adaptive meshing, mass scaling and parallel processing techniques are incorporated to obtain sound simulations, using a high temperature, strain rate sensitive material model. The strain distribution in different thickness layers and axial positions of the curved tube are studied and deformation modes are interpreted. The distribution of the axial strain along the tube axis in different thickness layers indicates the bending mode deformation at the distant positions from the free end and elongation at the free end, where shear also increases significantly. In all, a comprehensive description of the plastic deformation in tube spinning, considering the strain variation in thickness, is presented in this paper. Roller force in axial direction changes sign because of change in relative contact position of the roller and tube. The radial force is also shown to be slightly decreasing towards the end. [Copyright &y& Elsevier]

Abstract: In conventional spinning, multiple roller passes are required to prevent material failures and to minimize thinning of wall thickness of spun parts. In the present industrial practice, the process design still relies on the trial-and-error approach to determine roller path and passes. In this paper, a tool compensation technique has been proposed and employed in multiple roller passes design, to ensure the workpiece fully conforming onto the profile of a mandrel. The Taguchi method is applied to design experimental tests and analyze the effects of material type, feed ratio and spindle speed on the dimensional variations of the spun parts. Finite element simulation is conducted to investigate the variations of tool forces, wall thickness and strains in this multi-pass conventional spinning process. The results show that the tool compensation technique can effectively prevent material wrinkling failures in the process. The type of material has the most significant effects on the variations of thickness and depth of the spun parts, followed by the spindle speed and the feed ratio. High feed ratios can help to maintain the original wall thickness unchanged but cracking failures may occur if a larger feed ratio is applied. [Copyright &y& Elsevier]

Abstract: Sheet metal spinning has seen significant developments in recent years. However, in the present industrial practice, the process design still highly relies on undocumented expertise; trial-and-error approach is commonly used to design the roller path and passes. In this paper, four different roller path profiles, i.e. combined concave and convex, convex, linear, and concave, have been designed and used to carry out spinning experiments and to conduct finite element (FE) analysis. The effects of these roller paths on tool forces, part wall thickness and stress variations in conventional metal spinning have been analysed numerically. The results show that the concave path produces highest tool forces among these four roller path profiles. Using the concave roller path tends to cause higher reductions of wall thickness of the spun part and using the convex roller path helps to maintain the original wall thickness unchanged. A greater curvature of the concave path would result in more thinning in wall thickness of the spun part. [Copyright &y& Elsevier]

Tube spinning process is a metal forming process used in the manufacture of axisymmetric products and has been widely used in various applications. Finite element analysis has been successfully applied to the tube spinning processes, but no temperature effects have been considered on neck-spinning. For this reason, the aim of this research is to investigate numerically the neck-spinning process of a tube at elevated temperature. The commercial software Abaqus/Explicit was adopted in the simulation. For the construction of the material model, special uniaxial tensile tests were conducted at elevated temperature and various strain rates, since the material is sensitive to strain rates at high temperature. Comparisons between experimental and simulation results on thickness distribution and the outer contour of the spun tube are discussed. During the final stage, the average deviations between the simulation and experiment were 10.65% in thickness and 3.03% in outer contour. Good agreement was found between experimental and simulation results. The influence of the coefficient of friction, roller translation speeds, and the tip radius of the rollers were also investigated through numerical simulation. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports a study on material deformation during a multi-pass conventional spinning. A Finite Element (FE) analysis model has been developed based on a 5-pass conventional spinning experiment. The explicit Finite Element solution method has been used to model this multi-pass spinning process. Effects of mass scaling and reduced integration linear element used in the FE simulation have been evaluated by using various energy histories obtained from the FE analysis. The numerical results suggest that among three tool force components the axial force is the highest while the tangential force is the lowest. Certain correlations have been found between the FE analysis results and measured dimensions of the spun part. The blank thickness decreases after each forward pass and there are almost no thickness changes during the backward pass. Stress distributions of the local forming zone of the workpiece in both forward and backward passes have also been analysed, which gives an insight into the material deformation during the spinning process. [Copyright &y& Elsevier]

Spinning process is an advanced plastic working method, which is frequently used for manufacturing of axisymmetric shapes, especially those that cannot be easily produced with deep drawing method. In this article, a three-dimensional explicit finite-element (FE) analysis is employed to simulate the spinning process of an aluminium circular sheet. To achieve a wide range of strain distribution in different directions, a hemispherical cup has been chosen as the final product shape. In addition, a theoretical shear forming as well as a conventional model has been employed to estimate strain distribution in the spinning hemispherical cup. Experimental tests are carried out using a spinning machine and a hemispherical mandrel. Finally, FE and theoretical calculations are compared with the experimental results. A good agreement has been demonstrated between numerical and experimental results but a relative agreement with theoretical calculations. [ABSTRACT FROM AUTHOR]

Abstract: Flow forming, as a kind of metal spinning processes, is mainly used to produce thin-walled high-precision tubular components. In this study a coupled set of experiments and numerical simulations using the commercial finite element code ABAQUS/Explicit was used to study the evolution of redundant strains in a single-roller flow forming process in one pass. The modified embedded pins were used to evaluate the shear strains. It is shown that high shear strains occur not only at the longitudinal but also at the cross section. Sketched longitudinal lines also show that ɛ θz of the cylindrical coordinate system cannot be neglected. Beside of the shear strains, reversal straining is recognized as another type of redundant work. It is shown that this type of redundant strain results from the incremental nature of flow forming process in which the deformation is highly localized. Good agreements between the force measurements of frictionless model simulations with the experiment imply that the frictional work can be neglected in comparison to the redundant work. [Copyright &y& Elsevier]

Abstract: The correlations of microstructure and texture with deformation history in backward tube spinning were studied. Deformation history was calculated with initial and some intermediate configurations as reference configuration from FEM analysis. Microstructure and texture were investigated in the experimental workpiece of Ti–6Al–2Zr–1Mo–1V. The results show an obvious through-thickness inhomogeneity in deformation, microstructure and texture. Large material rotation occurs and plenty of grains are kinked and distorted in the outer layer, especially when thick-wall billet is spun. Deformation difference diminishes with wall thickness decreasing. The inhomogeneity of as-spun microstructure is reduced obviously in multi-pass and large deformation (for example, 85% total reduction) tube spinning. {0002} texture develops generally without orthotropic symmetry. Textures in the outer and inner layers evolve differently because of inhomogeneous deformation histories. [Copyright &y& Elsevier]

Abstract: As a successively and locally plastic deformation process, backward ball spinning is applied in order to manufacture thin-walled tubular part with longitudinal inner ribs. Based on the experiments and rigid-plastic finite element method (FEM), the influence of the ball size on deformability of thin-walled tubular part with longitudinal inner ribs during the backward ball spinning is investigated in the present study. The size of ball plays a significant role in backward ball spinning of thin-walled tubular part with longitudinal inner ribs. The size of the ball not only is a critical factor in determining the magnitude of the spinning force, but also has a great influence on the surface finish of the spun part, the steady flow of the metal material as well as the formability of the inner ribs. The results have shown that increasing the size of the balls contributes to the formability of the inner ribs as well as the steady flow of the metal material on the surface of the spun part, but too large ball size leads to poor dimensional accuracy and inferior surface quality of the spun part. [Copyright &y& Elsevier]

This paper reports the results of modelling of the spinning of thin sheet aluminium with the MSC MARC finite element (FE) package and its domain decomposition facility using Patent MPI software. The use of networked computers, both single and dual processor machines, is compared. The network used consists of over twenty computers and a 3COM switch with a nominal capacity of 100 Mbit/s. The effect of reduced network capacity is noted. The effect of increasing the number of computers involved is investigated in terms of resulting solution times. The results show the potential for large reductions in solution times. The impact of the background support of a network solution on the conventional computer user is examined.Partitioning of the model into ‘super-elements’ or separate domains is reviewed. Various partitions of the meshed geometry are compared, giving some indication of where pitfalls may lie in this critical aspect of multi-domain FE models.The results of the modelling are compared with experimental measurements of a conventional spinning operation using a CNC lathe. A flat disk is formed by a spinning operation into a dished shape. The material used is commercially pure aluminium. [Copyright &y& Elsevier]

The influences of different shape, size and number of lateral cutouts at various locations on the load-bearing capacity, buckling behaviour and energy absorption (E abs) characteristics of aluminium conical frusta under quasi-static axial loading condition were studied from both experimental and numerical procedures. In this regard, 18° semi-apical angled aluminium conical (AC18) frusta were fabricated through the metal spinning process; and circular, square, and trapezoidal shapes of cutouts with required dimensions were introduced at various lateral locations of the frustum. These conical frusta were subjected to quasi-static axial loading at a rate of 2 mm/min using a universal testing machine (UTM), and the corresponding load-deformation characteristics were recorded for axial compression of 50 mm from its original height. In addition to that, similar to experimental studies, Finite Element Analysis (FEA) was performed with conical frusta having various cutouts using ABAQUS® finite element software to study the influence of cutouts on the changes on crashworthiness performance of conical frusta. From both studies, it is observed that the energy absorption capacity of 18° semi-apical angled aluminium conical frusta was found to be decreasing in the range of 3.67%–47.60% according to the shape, size, number and location of cutouts. Further, the load resistance parameters such as first peak load (P fst), maximum peak load (P max) and average load (P avg) also are found to be decreasing with an increase of cutout size. The change of cutout location from mid-height to three-fourth from the base of the frustum also resulted in a reduction of E abs capacity, regardless of shape, size and number of cutouts. From these studies, it observed that the energy absorption characteristic of conical frusta having circular cutouts are found to be better than the conical frusta having square and trapezoidal cutouts at same locations. It is also observed that the E abs capacity of conical frusta having cutouts was found to be non-linearly decreasing with the linear increase in the number, location, shape and size of cutouts. The specimens with a large-size of cutouts had exhibited large deformation over the cutout region that led to an unstable non-linear global buckling during axial compression. Consequently, their E abs capacity was found to be decreased significantly as compared with the conical frusta with a small size of cutouts. The specimens with the small size of the cutouts exhibited progressive local buckling during axial compression, and they exhibited better energy absorption characteristics as compared with the conical frusta with large size of cutouts. Image 1 • The crashworthiness characteristics of thin-walled aluminium conical frusta with circular, square and trapezoidal shapes of cutouts are investigated under quasi-static loading conditions through ABAQUS software and validated with exprimental studies. • The influence of location, shape, and size of cutouts on crush performances 18° semi-apical angled specimens are reported elaborately. • The change of buckling modes with the change of cutout shape and location are also discussed. [ABSTRACT FROM AUTHOR]