Papers by Author: H. Haghighat

Abstract: In this paper, the process of bi-metallic tube backward extrusion through a conical punch, by means of upper bound method and finite element method is investigated. A cylindrical admissible velocity field is developed and by calculating the internal, shear and frictional powers, the extrusion force is estimated. The extrusion process is also simulated by using the finite element code, ABAQUS. Analysis and simulations are done for two types of bi-metallic tubes: aluminum as core, copper as sleeve (Al-Cu) and copper as core, aluminum as sleeve (Cu-Al). The extrusion force from the upper bound method is compared with the Finite Element results. This comparison shows that the upper bound predictions are in good agreement with the Finite Element results. The results also show that, the extrusion force in the case of Al-Cu tube is smaller than Cu-Al tube and in both types of bi-metallic tubes, the aluminum leaves the deformation zone sooner than the copper. Finally the effects of various extrusion parameters, such as the friction factor, reduction in area and semi-punch angle upon the extrusion force are investigated and the optimum semi-punch angle is determined.

Abstract: Lateral extrusion of gear- like components with radial tooth profile, has been studied in this paper. To analyze the process, the two types of theoretical approaches, i.e. the upper bound technique and the slab method of analysis have been applied and extrusion load values have been estimated. The theoretical results of load values estimated from the above approaches have been compared with theoretical and experimental results that given by a reference. Good agreement has been found among the predicted load values and those obtained from the experimental results.

Abstract: The process of lateral extrusion of gear-like components with radial tooth profile has been studied in this paper. The material flow in extrusion die cavity has been simulated using the SuperForge of FVM simulation package. The results of simulation have shown that the material fills the die cavity in two stages: Parallel movement to the end of toothed die cavity and fills the rest of shaped die cavity. Each stage of deformation has been analyzed by using slab method of analysis and the extrusion load values for each punch stroke have been estimated. Finally, comparisons between present theoretical results and experiments of other researchers’ work have been carried out to illustrate the validity of this proposed model.