Papers by Keyword: High Energy Rate Forming

Abstract: A frequent application of electromagnetic forming in the industry is joining by electromagnetic compression of tubular parts. The goodness of the joints is determined by the strength of the joint, and it is considered excellent if it reaches the strength of the weaker material pair. Strength of these joint are generally tested for tensile and torsion loadings. In order to increase strength, one or more horizontal and/or radial grooves can be fabricated onto the male joining pair to utilize form fitting besides interference fit. In the present paper, the strength of the joint is studied by finite element simulations.

Abstract: Electromagnetic forming is a high speed forming process, wherein the forming pressure is created by high energy density electromagnetic pulse. Besides direct shaping there are other application areas as well, so electromagnetic plastic forming is a potential field of creating joints between tube and rod-like components. Connecting components of dissimilar materials is an increasing demand in the manufacturing process of structures in the automotive industry. The application of new technologies, such as electrodynamic, especially electromagnetic forming, is a possible method to satisfy these demands. The article summarizes the most important fundamentals of electromagnetic forming; in particular, tube-rod joints, the main types of such joints; interference-fit and form-fit joints are described. Experiments, which were carried out producing tube-rod joints with electromagnetic forming, are also introduced. A new type of form-fit joints for tube-rod connections has been developed, which can withstand not only tensile loads but also torsion. Experiments and mechanical tests have proved the applicability of this kind of joints.

Abstract: Two types of electrodynamic forming process have been developed: electromagnetic and electrohydraulic forming. In the case of electromagnetic forming, the energy stored in a capacitor bank is discharged through a coil, which means that the electrical interaction between the coil and the plate or a tubular part to be formed results in deformation of the workpiece. However, in the case of electrohydraulic forming, the capacitor bank is discharged through a spark gap or filament wire; the deformation of the workpiece is due to the shockwaves, generated by the discharge process in a transmitting medium. In both processes, a large amount of energy is released in extremely short time, therefore these processes are considered to be high energy rate forming processes. These high energy rates, result in increasing the formability of the materials in many cases, and obtain significant deformations also for some materials that normally do not behave plastically. The utilization of the energy stored in the capacitor bank is significantly better in the case of electrohydraulic forming, because the released energy is converted directly to pressure waves, results in forming of higher strength materials. Both metallic and non-metallic materials can be formed by the technologies of electromagnetic and electrohydraulic technologies. In the present paper some aspects and applications of these high energy rate methods are briefly outlined mainly focusing on the automotive industry, involving expansion or compression forming of tubular parts, joining and assembly operations.

Abstract: In this paper, we describe an electromagnetic bulging for a SUS304-O stainless steel sheet (0.15 mm thick) and its experimental results. In the die forming, the flat one-turn coil is adopted for the bulging of the SUS304-O sheet, when an aluminum sheet (0.3 mm thick) as a driving plate (driver) is used together. When an impulse current from an energy-storing capacitor bank passes through the flat one-turn coil, a high-density magnetic flux is suddenly generated around the coil. Eddy currents are induced in the driver placed on the coil. The SUS304-O sheet is pressed by an electromagnetic force generated in the driver, leading to bulge into a meandering groove with small concave shape. The bank energy required for the bulging of 12mm wide, 60mm long and 0.43mm high is about 4.5 kJ, and the obtained workpiece does not almost have wrinkles and curves.

Abstract: This paper proposes a seamless microforming technique from 100 micrometer order bulging all the way down to micrometer-order embossments by using hydro spark forming method. Sub-millimeter order bulging with 300 and 100 m diameter aluminum thin foils are demonstrated to be easily available without accurate positioning as in the conventional methods. The present technique is successfully applicable also to surface embossments of micrometer order, for a coin surface, an IC chip and hologram surfaces.

Abstract: The aim of the present work is to produce new types of solid nanomaterials for different purposes (coatings, fillers, foams, bulk pieces, etc.). Technologies such as RS Al flake production, high energy mechanical milling and high energy rate forming technology (HERF) for compacting are used. The products are analyzed mainly by XRD, SEM and TEM methods. It was shown that the new-type of RS Al “flake” material is suitable not only for pigments but also for powder metallurgical purposes, i.e. Al based nanocomposites. By choosing suitable parameters for mechanical alloying with the Fritsch Planetary mill 4, very fine, alloyed and composited nanostructures can be produced (Al-4.5w%Cu- 10w%Al2O3, Al-15w%Pb) Dynamic compaction (HERF) using explosive techniques seems to offer a good way for the compaction of Al (metal) matrix nanostructured composites.