Papers by Keyword: Net-Shape

Abstract: Recent years have therefore seen growing interest in gear precision forging to net-shape form of forge bevel, spur and helical gears, as an alternative to conventional manufacturing. In this paper, gear precision forging processes are simulated by using metal forming finite element code DEFORM-3D. The investigations of gear precision forging processes are conducted with perform forging and final forging processes. The processes of completely closed-die forging, moving-die forging and central divided flow forging processes are investigated for spur gears. The effect of different processes on the distribution of effective stress in the workpieces and forging loads are given. The purpose of this study is to introduce a new method, a so-called floating-relief method which applied to the forging of spur gears. It indicated that the flowing properties of the gear billet have a higher improve than that of conventional forging process. And the forging load obtained by using this new precision forging technology is decline sharply. The floating-relief method for gear precision forging is a sound process in the practical application.

Abstract: In this paper, a new precision forging technique composite processing of the moving-die forging and divided flow forging process to form the spur gear is introduced. A systematic investigation of the floating-relief method process is performed by using finite element numerical simulation. The stress distributions on the workpieces were obtained. The closer the die teeth corner is, the higher stress value results can be acquired. And the effective stress is concentrated in spur gears forging die cavity corner. It was found that the floating-relief method forging process with upper and lower convex punches control the material flow effectively and the tooth cavity is filled successfully during the performing forging and final forging. The proposed method can serve as preconditions to analyze the abrasion and fatigue of spur gears forging die. The obtained results can offer valuable guidelines for gear precision forging experiments and practical process planning.

Abstract: Spark-plasma sintering (SPS) is an emerging powder consolidating technique which provides significant advantages to the processing of high temperature materials with poor deformability into configurations previously unattainable. Net-shaping capabilities of spark-plasma sintering are analyzed both theoretically and experimentally. Modeling and experimentation are conducted for cylindrical, prismatic, and complex powder specimen shapes. The impact of the “shape factor” on the non-uniformity of temperature, relative density, and grain size spatial distributions is analyzed. The modeling results are compared to the experimentally obtained data on the spark plasma sintering of high strength temperature resistant powder-based materials. The conducted research indicates the promising capabilities and addresses the challenges of spark-plasma sintering of complex-shape parts.

Abstract: To enable sintering net-shape capabilities, a novel procedure for the fabrication of net-shape functionally graded composites by electrophoretic deposition and sintering are developed. The initial shape of the green specimen produced by electrophoretic deposition is designed in such a way so that the required final shape is achieved after sintering-imposed distortions. The shaped components can be metals, ceramics, polymers, and their combination as long as the material is in the form of powders. Through adjustment of an externally applied electric field and the shielding of electrical filed, the particles in the slurry are selectively deposited onto the porous mold which defines the desired geometry. By changing the slurries’ composition, the deposited component’s composition can be precisely tailored.

Abstract: The aim of this study is to optimize the economic net-shape forming of titanium and titanium alloys for the biomedical application. The alpha-case formation reaction between titanium, and Al2O3, ZrO2, CaO stabilized ZrO2 and ZrSiO4 mold were examined in a plasma arc melting furnace. Regardless of the thermodynamic approach, α-case formation reactions still remain to be eliminated with the complex chemical milling processes. The reason why the α-case generated cannot be explained by the conventional α-case formation mechanism. However, from the experimental results and thermodynamic consideration, it can be confirmed that the α-case is formed not only by interstitial oxygen atoms but also by substitutional metal atoms dissolved from mold materials. Based on the interstitial and substitutional α-case formation mechanism, α-case controlled net-shape forming of titanium and titanium alloys can be possible for the biomedical application.

Abstract: Cost effective ceramic manufacturing with green and dense machining perspectives has been described. An advanced CNC green machining based complex shape forming technology developed at Saint-Gobain is described which has been shown to be robust and capable of rapid prototyping. Utilizing a systems approach involving green blank properties, type of cutting tools and machining parameters the procedure has been optimized. Integral Bladed Rotors (IBR) for microturbine applications have been fabricated with dimensional controls within 0.15% and successfully spin tested at 143330 rpm without failure. Following this approach, a cost effective machining and prototype fabrication procedure is under development for IBR and Vane rings for various civilian and military applications.