Papers by Keyword: Explosive Forming

Abstract: This study has investigated the plastic forming of magnesium alloys plate. It is not easy to perform the cold-worked with the usual plastic forming method although magnesium alloys have the advantages in terms of strength-to-weight ratio. Therefore, explosive forming method which is one of the plastic forming methods with a specific forming mechanism has been applied. At first, numerical simulations have been conducted to clarify the optimal combination conditions, and then we have verified practical effectiveness of this proposed method by using experimental study.

Abstract: In this paper design and analysis a die meant to cone explosive forming have been investigated. Since the explosive forming dies are subjected to blast loading, failure is too likely to pass. Likewise, the special geometry such as existing the several holes, sealing grooves, vacuum channel and fillets of this type of dies under explosion wave makes their analysis complicated. In the present work, the die was designed according to the final product dimension assisting a design software. In the next step the die under blast loading was analyzed using finite element method utilizing FEM software. The outcomes exhibit that the die is capable to withstand the explosion load. Besides, the trend of this paper is recommended as a routine for the designers who are going to design these types of dies.

Abstract: t is well known as an important merit of the explosive forming process that the delicate figure of the die surface is precisely transferred onto the specimen of a thin metal plate, because the plate is strongly pressed against the die by the very high pressure of underwater shock wave. However, we cannot find any examples of work pieces making the best use of the merit in literatures until now. We tried to form explosively a thin copper plate into shapes of a palm and a back of human hand, as a work piece making the best use of the merit. The palm has many small delicate lines such as fingerprints and the back has interesting figures such as loose skin at the joints of fingers and the borders of fingernails. The object of the present investigation is to make work pieces just like to a real hand. In this investigation, the following process is adopted in order to perform successfully explosive forming ; real hand plaster concave model convex model of Duplicone (material for dental impression) die of Ren Cast (a kind of epoxy resin) explosive forming. Annealed copper plates of 0.3 mm thick were used in the experiments. Since the extension limit of the plate is not so large, the plate is apt to be broken. If the plate is broken, the die is modified not to break the plate. Though the die made of epoxy resin is too hard to be modified, the plaster model can be easily modified with a cutter knife or a chisel. The modified die is obtained through model of Duplicone made by using the modified plaster model. After a few times of repeating modification, the breakage of plate was scarcely produced. On the work piece of palm, a lot of small lines including finger prints clearly appeared and the work piece of the back showed the shape just like to real human hand.

Abstract: Explosive forming is one of the unconventional techniques, in which, most commonly, the water is used as the pressure transmission medium. The explosive is set at the top of the pressure vessel filled with water, and is detonated by an electric detonator. The underwater shock wave propagates through the water medium and impinges on the metal plate, which in turn, deforms. There is another pressure pulse acting on the metal plate as the secondary by product of the expansion of the gas generated by detonation of explosive. The secondary pressure pulse duration is longer and the peak pressure is lower than the primary shock pressure. However, the intensity of these pressure pulse is based also on the conditions of a pressure vessel. In order to understand the effects of the configuration of the pressure vessel on the deformation of a metal plate, numerical simulation was performed. This paper reports those results.

Abstract: In the aerospace industry lightweight design in combination with fast and reliable manufacturing processes are key components to defend the leading position in the worldwide competition. In this frame it is an overall goal to reduce the number of process steps in order to produce parts for an aircraft to its minimum. Integral design is one way to cope with this goal but on the other hand raises a lot of problems that may occur in manufacturing or final assembly. To be able to predict potential bottlenecks or drawbacks in certain designs, finite element simulation can be helpful. Especially if it’s an early design phase and new material concepts are taking into account, the virtual manufacturing, done by finite element simulations is the only way to predict real life behavior. In this paper we will focus on the use and benefit of finite element simulations in the early design phase of very huge integral parts of a next generation aircraft. The parts do belong to the nose fuselage structure and will be manufactured from a 100-150mm thick AlMgSc plate. Two different manufacturing routes will be covered by simulation. 1. Hot forming the plates at around 300°C and machining 2. Explosive forming of the plates and machining For both routes, a complete simulation chain from forming over springback to final machining is developed and presented in detail. Special care is taken on a fully automated workflow from one step to the other to allow an easy adaptation to other part geometries in the future. To ensure a high quality of the simulation results all process steps of the hot forming route are simulated with ABAQUS implicit and approved constitutive laws. The explosive forming manufacturing route is simulated using an Eulerian-Lagrange approach taken into account the various possibilities of detonation loading. To validate the simulation results to real measurements, a scaled down version of one of the parts is manufactured in reality and each process step is compared with the simulation result.

Abstract: Explosive forming is one of the effective metal forming methods using underwater shock wave generated by the detonation of an explosive. We have done the experiment of eccentric spherical free metal forming by this method. This free metal forming process does not use require expensive metal die. We used simple metal die with only circular edges and considered the metal plate formed to required shape using this method. It was possible to change the pressure distribution applied on the metal plate by changing the set-up position of explosive and the shape of the device. We have considered this method to cause lessen cost in the small production by various types of metal forming process. In this paper, we introduce the method of eccentric spherical free metal forming using underwater shock wave and present the experimental results.