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Potthast J.-M.,IPH Institute fur Integrierte Produktion Hanover gemeinnutzige GmbH | Meers S.,IPH Institute fur Integrierte Produktion Hanover gemeinnutzige GmbH
Productivity Management | Year: 2012

In this contribution characteristics of xxl goods and basic aspects of the construction of production systems (e. g. principles, methods) are discussed. In the context of an expert interview at producers of XXL goods the methods of the production systems most frequently used are identified. The contribution introduces the results of the expert interview and closes with an outlook about the further procedure. © GITO Verlag.


Ciupitu I.,Science METAV RandD Ltd. | Ioncea A.,Science METAV RandD Ltd. | Taca M.,Science METAV RandD Ltd. | Vasile E.,Science METAV RandD Ltd. | And 2 more authors.
UPB Scientific Bulletin, Series B: Chemistry and Materials Science | Year: 2015

The vanadium carbide precipitates in microalloyed steel for automotive crankshaft are investigated using High Resolution Transmission Electron Microscopy (HRTEM). The presence of cubic ordered V8C7 nanocarbide has been unequivocally highlighted, after the forging of 38MnVSi6 vanadium microalloyed steel by a new multidirectional flash reduced technology. The literature provides few data relative to the unambiguous presence of V8C7 non-stoichiometric carbide, obtained by different other methods in Fe-C-V alloying system. Nanometric carbide precipitates (〈3nm) lead to the increase of this HSLA (High-Strength Low-Alloy) steel toughness.


Kache H.,IPH Institute fur Integrierte Produktion Hanover gemeinnutzige GmbH | Stonis M.,IPH Institute fur Integrierte Produktion Hanover gemeinnutzige GmbH | Behrens B.-A.,IPH Institute fur Integrierte Produktion Hanover gemeinnutzige GmbH | Behrens B.-A.,Leibniz University of Hanover
Production Engineering | Year: 2012

Cross wedge rolling is a forming technology that offers a lot of advantages: No flash occurs, cycle times are low, lubricants are not necessary and the machines are easy to automate. Currently, cross wedge rolling is applied at hot temperatures only. An adaption of this technology to warm temperatures (about 500-950 °C) can increase the geometrical spectrum of warm forgings. The advantages of warm forged parts in comparison to hot forged parts are closer tolerances, reduced surface roughness, no scale and reduced decarburization. To apply cross wedge rolling at warm temperatures, the possibilities of defects e. g. internal voids and improper formed work pieces must be analysed. This paper describes the development of a warm cross wedge rolling process with one area reduction. The paper also includes results of finite element analysis (FEA), experimental trials with a downsized work piece and the adaption to the industrial work piece in original size. In the FEA simulations tools with serrations on the side have been used. The downsizing method is explained and the difference between FEA, downsized and originally sized work piece with the focus on forming forces, temperature distribution and defects are presented. © 2012 German Academic Society for Production Engineering (WGP).


Behrens B.-A.,IPH Institute fur Integrierte Produktion Hanover gemeinnutzige GmbH | Nickel R.,IPH Institute fur Integrierte Produktion Hanover gemeinnutzige GmbH | Stonis M.,IPH Institute fur Integrierte Produktion Hanover gemeinnutzige GmbH
Production Engineering | Year: 2012

In automotive industry, parts made of aluminum alloys are used with increasing frequency. During forging operations for the production of aluminum long flat pieces, defects like folds can appear. Especially internal folds are of interest, which are only evident in the fiber orientation and have a negative effect on the dynamic mechanical properties of the forged part. In forging, the forming operation can be realized either from one direction (uni-directional) or from several directions (multi-directional). The boundary conditions for multi-directional forging are described in this article. For a given tool geometry, multi-directional forging permits the realization of fold-free forgings, which has been shown to be not possible with uni-directional operations. A newly developed method based on finite-elements-analysis simulation helps with the design of the forming process and the determination of the appropriate tool geometry. A new algorithm integrates the computer-aided identification of internal folds. For a given process and tool geometry, the area with internal folds is adjusted, until the simulation shows no fold formation. It is shown, that by using this model, a dependable assessment and correction of forging tools and forming process and thus the realization of a fold-free forming are possible. © 2012 German Academic Society for Production Engineering (WGP).


Krause A.,IPH Institute fur Integrierte Produktion Hanover gemeinnutzige GmbH | Weirauch R.,TU Braunschweig | Brauer G.,TU Braunschweig | Stonis M.,IPH Institute fur Integrierte Produktion Hanover gemeinnutzige GmbH | Behrens B.-A.,IPH Institute fur Integrierte Produktion Hanover gemeinnutzige GmbH
Production Engineering | Year: 2014

The reduction of die wear is an effective way to decrease costs within bulk forming processes. Therefore, specific tool materials and heat treatments as well as special coatings are used to prolong the lifetime of the tools. Diamond-like carbon (DLC) coatings show high hardness and superior frictional behavior. However, these coatings seem to be inappropriate for hot forming due to degradation processes at elevated temperatures. But for warm forming, due to the lower temperature input into the cavity, DLC might be an appropriate coating. Friction influences the shear stresses on the cavity surface and is therefore an important factor for reducing die wear. Hence, the analysis of the frictional behavior of DLC coatings within warm forming by using the ring compression test will be presented within this paper. An amorphous hydrogenated carbon coating and six metallic doped amorphous hydrogenated carbon coatings (Cr, V and W each in two variants) are compared to CrN and no coating. Firstly, nomograms are graphed by the use of finite-element-analysis. Thereafter two test series are carried out varying forming temperature and lubrication. The results show that DLC coatings with and without metallic doping are able to reduce friction in warm forming. Within the investigations, an amorphous hydrogenated carbon doped with 15 % chromium shows the lowest friction factor and is able to reduce the friction factor compared to no coating by up to 64 % within warm forming. © 2014, German Academic Society for Production Engineering (WGP).

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