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Tubular components, such as stepped tubes, conical tubes and box-shape tubes, are mainly produced by tube hydroforming process. Obtaining a sharp corner is the main goal in some of these components. In this paper, corner filling in stepped tubes is studied using a new multistage hydroforming die. The proposed die was simulated and filling of the die cavity was investigated. The finite element software, ABAQUS 6.4, has been used for simulation. In order to verify the simulation results, the new die of stepped tube was manufactured and then experiments have been performed on it. The results of the experiments verified the simulation results. It was shown that by using the new die, parts with sharp corners could be produced. The simplicity of the die and the low internal pressure are among the advantages of this die.Thickness distribution was also examined by FE simulation and via experiments and it is shown that a better distribution could be obtained by the proposed die set.

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In recent years the use of metallic bipolar plates for fuel cells is considered. Several studies have been conducted on the various methods of forming these plates. Most of this research has been done on the serpentine flow fields. While in some cases that the pressure drop is important factor, the pin-type flow fields shows good performance. In this research, hydroforming of metallic bipolar plates with circular pin-type pattern from stainless steel 304 with 0.11mm thickness is investigated experimentally and numerically. For this purpose, the effect of geometrical parameters such as the die wall angle, the die chamfer dimension, the depth-to-width ratio of the die, and forming pressure on the profiles, filling percent, thickness distribution and thinning percent of the formed parts are investigated. In this regard, two dies with wall angle of 0 and 15 degree were prepared. Then experimental tests were done at different pressures. After performing the required tests, the results show that the die wall angle leads to a more uniform thickness distribution and higher precision of the parts profile. Also the suitable range of die geometrical parameters was determined.

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Aluminum alloys have become widespread in the various industries due to the characteristic of high strength-to-density ratio. These alloys do not have a suitable formability at ambient temperature so they formed at high temperatures. The main hot forming methods used for aluminum alloys include deep drawing and gas forming. Both of these methods have their own advantages and disadvantages. In this study, a combined process involving deep drawing and gas forming has been used. In this process, the first step is to create a pre-formed deep drawing and in the second stage, the final piece is produced by gas forming process. The purpose of this study is to optimize the levels of the main process parameters for the shaping of cubic parts of aluminum sheet 5083 sheet. These parameters include the temperature and blank-holder force of deep drawing stage and the temperature and gas pressure at the gas forming stage. The best levels of process parameters were selected using the Taguchi experimental design method. The results show that the temperature at 350 ° C and the blank-holder force of 1000 N for deep drawing, as well as the temperature of 485 ° C and the gas pressure of 0.6 MPa for the gas forming stage, can be achieved with the least degree of thinning in the specimen. The maximum thinning achieved is 22%.