A new cold precision forging technique is proposed to form a spur gear from a hollow billet, that is blocking the divided flow region and then final forging by the relief hole. 3D2FEM simulation of the whole process of a pure alu-minium spur gear is performed using DEFORM-3DTM. The load-stroke curve, effective stress distribution, effective strain distribution, velocity distribution, and so on, are achieved. These results are compared with those achieved using the conventional closed die forging in the same conditions. The results show that this new technique has many advantages over the conventional one. The deformation load is reduced by near 30% and the filling ability of the tooth profile is also improved. Precision forging experiments of spur gears with the new process were performed using material Pb. The experimental results show a good agreement with the numerical results.

The support shaft is a key part in the automobile industry. Its annual production quantity is usually very large. The current manufacturing process is conducted with much machining work including drilling the hollow, which results in a great waste of material. This paper gives a new manufacturing method by the implementation of extrusion processes. It can not only save much material but can also improve properties of the support shaft. The new manufacturing processes include a two-stage extrusion process. A reasonable preform shape was determined through finite element based simulation. Thewhole forming process is simulated and verified by the finite element method using the DEFORMTM system. The die designs of the two extrusion processes are also given. The two-stage extrusion process and related die designs were recommended to one forging company that presently manufactures the support shaft with the traditional method.

In order to obtain high property powder metallurgy products, at present rotary forging process has often been used to further densify the sintered powder compact, but the densification law and property analysis have very rarely been studied, therefore the densification laws of sintered powder compacts being composed of Fe-0.8%C-4.0%Cu-0.2% zinc stearate and formed as cylindrical shape by double action pressing, and then further densified as well in a rotary forging process was studied by orthogonal experiment and regression analysis. The experimental results show that the H/D ratio and the rotary forging force are major factors affecting the density of the sintered powder compacts in the rotary forging process. The effect of the H/D ratio and the rotary forging force on the density were discovered. By determining both the density and the hardness of compacts, it was found that the density distributions show no difference from the hardness dis-tributions and that the gradients of the density and the hardness in the axial direction are larger than those in the radial di-rection.

The deformation of a ring workpiece by the rotary forging process is analyzed using a three-dimensional rigid

The methods of dealing with some key problems in analyzing a rotary forging process with a finite element method are given. The presented mechanical model of the finite element analysis is in accordance with the actual conditions of the rotary forging process. A three-dimensional rigid–plastic finite element analysis code is developed in FORTRAN language and used to analyze the rotary forging process of a ring workpiece. Velocity fields and stress-strain fields of both contact and non-contact zones of the ring workpiece in the rotary forging are obtained. The deformation mechanism and metal flow laws of the contact zone surface of the ring workpiece in the rotary forging process are revealed. The pressure distributions of the contact surface along the radial and tangential directions and effects of rotary forging parameters on deformation characteristics are given.