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During metal forging, warping can easily occur on the edge of the thin flange, causing it to fold, affecting the sustainability of the application of the flange. This investigation proposes a chamfer design for the die and the taper design for the ring gap, to eliminate warping. First, the radial forging process of work-hardened materials is simulated, the phenomenon of flange warping is analyzed, and the accuracy of the simulation is experimentally verified. Secondly, the materials, lubricants and the height of the ring gap of the die are set as fixed parameters, and the analytical results for dies with rounded corner, chamfered and a tapered of the ring gap, are compared. The experiments and simulation confirm that the problem of flange warping can be solved effectively. The results are as follows.1. When the die has a rounded corner and R = 2 mm, serious warping and breaking creases are observed alongs the rim of the flange. 2. When the die is designed with a chamfer, experiments and simulation both demonstrate that warping is reduced slowly as the chamfer value increases. 3. When the die corner has a radius of R = 2 mm, and has a taper shape between the rounded corner and the ring gap, experiments and simulation both indicate that warping declines as the tapering increases. However, as the contact area between the raw material and the die increases, its forming load increases with the taper angle.All of these results indicate that the solution to the warping problem proposed herein is feasible and effective, and that the results of this study represent useful references for design dies for radial forging.

In this study, the finite deformation theory was used to develop a large rigid-plastic deformation finite element program which could simulate the radial forging process of work-hardening materials. First, experiments were carried out to confirm the accuracy of the program. Then we investigated the influence of each parameter on the forging process. The parameters adopted in this study are die corner radius (R), ring gap height (H), friction factor (m), and work-hardening coefficient (n). The effects of parameters on the flange thickness ratio (h/H) and the outer protruding shape ratio (D/D 0 ) are also obtained.The relationship between the process parameters and the deformation behaviours under radial forging is obtained through simulation. When the radius of die corner and the ring gap height are larger, the flange thickness ratio (h/H) becomes larger, but the outer protruding shape ratio (D/D 0 ) decreases. The value of friction factor (m) doesn't seem to affect the flange thickness ratio (h/H) much, but the outer protruding shape ratio (D/D 0 ) decreases upon increasing the friction factor. When the work-hardening coefficient (n) is larger, the flange thickness ratio (h/H) is also larger, but the outer protruding shape ratio (D/D 0 ) decreases.The results of this study offer some advanced knowledge about finding the best designs of process and die in radial forging process.

This investigation adopts the finite element method (FEM) and the artificial neural network (ANN) to plan the radial forging of work-hardened materials to yield the optimal designed die. The process parameters considered herein are die corner radius (R), ring gap height (H), friction factor (m), workhardening coefficient (n), gap between the billet and die (c) and the punch load ( f). The accuracy of the FEM model constructed herein is established. Fifty sets of processing parameters are simulated by the FEM, and the results, together with the outer rims of the flange after forming, are taken as the learning file in ANN. Then, based on the range that is set by the learning file, another 20 sets of flange with different shapes than those in the test file are selected to obtain a combination of parameters of the die, materials and lubricants and other factors. During the design of the die, many tests are conducted, and flanges of similar shapes are found to be obtained with various combinations of processing parameters. This result indicate that the learning pattern presented herein meets the needs of all types of parameter combinations. Finally, based on the required specification of the shape of the outer rim of the flange, this work uses ANN to obtain all the specified processing parameters. Finiteelement analysis is then used to confirm the accuracy of the results and further investigate the effect of the related parameters on the flange shape. The following conclusion is drawn: The design of the die can yield finished flange products with similar shapes using different parameter combinations. During the forming process, a suitable range of parameters is selected for the die, the materials and the lubricant. Then, according to the strength of their effects, their inputs and output values are appropriately adjusted and the most suitable combination of processing parameters identified according to the similarities in the flange shapes they produce.

This study investigates the formability of AZ31 and AZ61 magnesium alloy for bicycle parts under hot forging process. Firstly, finite element software DEFORM is applied to simulate the deformation behaviors of magnesium alloys bicycle parts under different process parameters. The process parameters considered in the simulation are materials heating temperatures, lubricants and punch speeds. Changes in process parameters, the forging loads and the completeness of filling of material in die cavity are discussed. The optimal forging condition can be obtained from evaluation of the completeness of filling of material in die cavity, forging load and distribution of stress and strain. The experimental conditions are set according to the optimal simulation results. Hot forging experiments are carried out under the condition of heating range from 240°C to 350°C, different kind of lubricants, constant punch speeds 0.9mm/s to study the formability of magnesium alloy for bicycle parts. The experimental results are compare with the DEFORM simulation results. The obtained forging loads and completeness of filling are in good agreement with the simulation results. The validity of the simulation model established in this study can be confirmed. Finally, from the measured result of hardness and metallographic observation of forged part, the influence of forging temperatures on the strength and microstructures of magnesium alloy for bicycle parts under forging process can be evaluated.