Sheet metal forming (SMF) is one of the most popular technologies for obtaining finished products in almost every sector of industrial production, especially in the aircraft, automotive, food and home appliance industries. Parallel to the development of new forming techniques, numerical and empirical approaches are being developed to improve existing and develop new methods of sheet metal forming. Many innovative numerical algorithms, experimental methods and theoretical contributions have recently been proposed for SMF by researchers and business research centers. These methods are mainly focused on the improvement of the formability of materials, production of complex-shaped parts with good surface quality, speeding up of the production cycle, reduction in the number of operations and the environmental performance of manufacturing. This study is intended to summarize recent development trends in both the numerical and experimental fields of conventional deep-drawing, spinning, flexible-die forming, electromagnetic forming and computer-controlled forming methods like incremental sheet forming. The review is limited to the considerable changes that have occurred in the SMF sector in the last decade, with special attention given to the 2015–2020 period. The progress observed in the last decade in the area of SMF mainly concerns the development nonconventional methods of forming difficult-to-form lightweight materials for automotive and aircraft applications. In evaluating the ecological convenience of SMF processes, the tribological aspects have also become the subject of great attention.

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Recent Developments and Trends in Sheet Metal Forming

Given their rapid development, aerospace and other high-tech industries are in urgent need of process technology for large complex thin-walled shells represented by large thin-walled parts with ring inner ribs and curvilinear generatrix. To make up for the deficiency in existing forming methods, this paper presents a compound spinning process that integrates counter-roller spinning, multi-neck spinning, and hot spinning. The finite element models for the counter-roller spinning and multi-neck spinning forming of such parts are established, and these models can simulate the influences of different spinning process parameters on workpiece maximum equivalent stress and maximum ovality. The 2A12 aluminum alloy tube blank is used in this paper. The process parameters for obtaining the counter-roller spinning for such parts are as follows: a feed ratio of 1.0 mm/r and a roller nose radius of 8 mm. The process parameters of multi-neck spinning are as follows: a feed ratio of 3.0 mm/r and a roller nose radius of 80 mm; and the forming temperature of hot spinning is 200–250 °C. Verification by a compound spinning test found that the numerical simulation results are consistent with the process test results. The process parameters can be used for guiding the actual production of large thin-walled parts with ring inner ribs and curvilinear generatrix.

Study on compound spinning technology of large thin-walled parts with ring inner ribs and curvilinear generatrix

Tube spinning technology represents a process with high forming precision and good flexibility and is increasingly being used in the manufacture of bimetal composite tubular structures. In the present study, a forming analysis of clad tube and base tube in spinning process was conducted through numerical simulations and experiments. There was an equivalent stress transition on the interface since the stress transmission was retarded from clad tube to base tube. The yield strength became a main consideration during a design bimetal composite tube. Meanwhile, the strain distributions in axial direction, tangential direction, and radial direction were also investigated to determine the deformation characteristics of each component. As the press amount increased, the strain of clad tube changed more than base tube. As the feed rate increased, the strain decreased in axial direction and tangential direction but almost unchanged in radial direction. Simultaneously, a method for controlling the wall thickness of the clad tube and the base tube is proposed. These results to guide the design of bimetal tube composite spinning process have the certain meanings.

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Analysis of the forming characteristics for Cu/Al bimetal tubes produced by the spinning process

Staggered spinning is a cost-effective method to manufacture axisymmetric components, especially for the ultrathin cylindrical parts. However, due to the complex material flow behavior during staggered spinning of Ni-based thin-walled cylindrical parts, the accurate control of geometric precision is still a great challenge. In this work, a three-dimensional (3D) finite element model (FEM) is developed to investigate the effects of staggered spinning parameters on the dimensional accuracy of a thin-walled Hastelloy C-276 cylindrical part. It is found that the deviations of wall thickness and inner diameter are sensitive to spinning parameters. Based on the results from the finite element analysis, the optimized spinning parameters are obtained for the studied thin-walled cylindrical part, i.e., an appropriate wall thickness reduction range is 30%–40% during the single pass spinning. Meanwhile, the effects of feed ratio on the uniformities of wall thickness and inner diameter are significant, and a suitable feed ratio is 0.8 mm/r. Finally, the industrial three-roller staggered spinning experiments are carried out to verify a fact that the developed FEM, as well as the optimized spinning parameters, can be effectively used for the staggered spinning of thin-walled Hastelloy C-276 cylindrical parts.

Staggered spinning of thin-walled Hastelloy C-276 cylindrical parts: Numerical simulation and experimental investigation

Metal spinning, as a kind of rotary forming process, is widely applied in the production of various areas. In this paper, the mathematical model of the conchoid roller path is proposed based on the cylindrical part and applied in the experiments. The possible problems of the roller path and the product shape are verified by 2D simulation, while the 3D simulation is used to predict the product dimensions and defects. Based on the advantage of both 2D and 3D simulation, the flow of target product trial production is proposed. The simulation is verified by the experiments with hard-deformed superalloy GH3030. The crack mechanism of cylindrical part spinning process is studied with a combination of macro- and micro-methods. Results show that the forming effect of the conchoid roller path is good; the flow can reduce the trial production cost and time. The grain elongated obviously at the crack zone while metal accumulated at the edge of the product which is the main cause of the crack.

Numerical and experimental analysis on multi-pass conventional spinning of the cylindrical part with GH3030

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.

A research on thickness distribution of oblique cone in dieless shear spinning

Spinning process is investigated to reveal the mechanism of square cross-section spinning without mandrel. The finite element model with the roller path formula as a boundary condition is established. Forge3D software is used to simulate the spinning process, and the accuracy of the finite element model is verified through experiment. From the stress–strain field, the residual stress on the surface of the workpiece is small after square cross-section cone hollow spinning and the maximum deformation locates on the middle part of the slope surfaces of the workpiece. The strain field distribution and the same Δr in different rotation round are the cause of the slight curvature that appears on the cross-section edge. The wall thickness decreases after hollow spinning, and the upper wall thickness is larger than the lower part.

Numerical simulation and experiment study on hollow spinning process for square cross-section cone

The non-axisymmetric cone has broad application prospects and is feasible to be manufactured via die-less shear spinning process which however lacks of research. With the roller path equation and other boundary conditions, the finite element model for non-axisymmetric die-less shear spinning process is established and simulated by adopting ABAQUS/explicit software in this study. The FEM results are experimentally verified by comparing the morphology and the HCAs. The distribution of stress and strain in different working conditions and the ellipticity and the elongation of the material in different spinning process during non-axisymmetric die-less shear spinning process are analyzed. It shows that the 0° area of the flange is the position where the wrinkle occurs easily, and the elongation of the material reaches the maximum value; the larger equivalent stress and strain distribute on the conical surface with the smaller HCA. With the movement of the roller, the ellipticity of the cross section increases in the bigger HCA working conditions, but decreases in the smaller HCA working conditions due to the combined effects of the deformation and the springback.

Numerical simulation and experimental study on the non-axisymmetric die-less shear spinning

A study of asymmetric multi-pass spinning for angled-flange cylinder

In view of the importance of the surface quality in the application to the square section die-less spinning, the effects of several key parameters which include roller path, half-cone angle, and roller nose radius on the surface quality are investigated Through the geometric model of residual height, the effect law of the roller path is obtained: the surface quality increases with the decrease of the axial distance of two adjacent slices Then the finite element model of the square section die-less spinning is established, and the normal force and axial strain states in the deforming process are adopted to predict the relationship between the surface quality and the half-cone angle Combined with the residual height model and finite element analysis, the roller nose radius’ effect on the surface quality is also obtained Enlargement of the two parameters can improve the surface quality All the analysis results are verified by the surface waviness test of the specimens from the workpiece after spinning

Zhen Jia

Papers

A research on thickness distribution of oblique cone in dieless shear spinning

Numerical simulation and experiment study on hollow spinning process for square cross-section cone

Numerical simulation and experimental study on the non-axisymmetric die-less shear spinning

A study of asymmetric multi-pass spinning for angled-flange cylinder

Effects of processing parameters on the surface quality of square section die-less spinning