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Behrens B.-A.,Institute For Integrierte Produktion Hanover Iph | Nyhuis P.,Institute For Integrierte Produktion Hanover Iph | Overmeyer L.,Institute For Integrierte Produktion Hanover Iph | Bentlage A.,Institute For Integrierte Produktion Hanover Iph | And 2 more authors.
Production Engineering | Year: 2014

The range of structure sizes for industrial products produced today is increasingly expanding. This trend is evident both at the bottom end of the scale as well as the top end. Examples include the ever-smaller miniaturization of devices in the semiconductor industry and the increase in rotor diameter of wind turbines. While definitions already exist for smaller scale device structures e.g. nanotechnology, the conceptual distinction between conventional large products and large scale products is currently insufficient. In this study, we present a potential basis for the definition of large scale products. To achieve this, we first of all derive hypotheses and examine these in the context of an empirical study using the examples of threaded nuts, screw presses and passenger aircraft. The study shows that the transition from conventional products to large scale products is characterized by a disproportionate increase in product costs due to the augmentation of a characteristic product feature. Based on the findings described, we then derive a proposed definition which characterizes large scale products on the basis that man encounters his technical, organizational and economic limits with the methods and tools available at the time of observation, in the context of product creation. © 2013 German Academic Society for Production Engineering (WGP).


Langner J.,Institute For Integrierte Produktion Hanover Iph | Stonis M.,Institute For Integrierte Produktion Hanover Iph | Behrens B.-A.,Institute For Integrierte Produktion Hanover Iph
Production Engineering | Year: 2015

Closed die forging with flash is the most common method of bulk forming processes. One main property of these processes is the use of a surplus material to ensure a complete filling of the cavity of the forging die. The surplus material is driven out of the die through the flash land. The design of the flash land has a major influence on the filling of the die. Usually, the dimensions of the flash land are fixed during the manufacturing of the die and can’t be changed within the forging process. Additional machining operations are necessary to adapt to e.g. different process parameters or to occurring die wear which deteriorates the filling of the cavity. By use of a variable and moveable flash gap which can be actively changed during the forging process more material can be held in the cavity, thus permitting the improvement of the filling of the cavity. Additionally, such a system can be used to adapt to varying process parameters within the process. In this paper the investigation of a variable flash gap will be described. The influence of such a system on the filling of the die cavity is determined. This is done by comparison with a conventional forging process with a fixed flash land. Additionally, different trigger forces of the variable flash gap were investigated which also have an influence on the material flow during the forming operation. At last, the results of experimental trials are compared to results of FEA simulations. Experimental trials showed that the variable flash gap has a clear influence on the material flow. The higher the flash ratio, the bigger is the influence of the variable flash gap. Differences in height of the parts of 4.6 mm, which correspond to 17.2 %, were reached between a conventionally forged part and a part forged with a variable flash gap. Different trigger forces also have an influence on the height of the parts. The higher the trigger force, the bigger the influence of the variable flash gap. In general, the results match the predictions of FEA simulations. Experimental trials showed that a variable flash gap is able to improve the filling of the cavity. This method can be used to increase the quality of forging parts by a much easier adaption to different process parameters without additional machining operations. © 2015, German Academic Society for Production Engineering (WGP).


Langner J.,Institute For Integrierte Produktion Hanover Iph | Stonis M.,Institute For Integrierte Produktion Hanover Iph | Behrens B.-A.,Institute For Integrierte Produktion Hanover Iph
Journal of Materials Processing Technology | Year: 2016

The most common method of bulk forming processes is closed die forging with flash. In these processes a surplus of material is used to ensure a complete filling of the cavity of the forging die. The surplus material is driven out of the die through the flash land, thus the design of the flash land has a major influence on the filling of the die. All dimensions of the flash land are typically fixed during the manufacturing process of the die and can not be changed within the forging process. By use of a moveable flash gap that can be actively changed during the forging process the material flow can be altered. This permits to improve the filling of the cavity. In this paper a moveable flash gap for a hot forging process is described and the influence of such a system on the filling of the die cavity is determined. This is done by a comparison to a conventional forging process with a fixed flash land. Furthermore, the results of experimental trials are compared to results of corresponding FEA simulations. Additionally, the influence of the initial billet temperature is investigated. Experimental trials showed that the moveable flash gap has a distinct influence on the material flow. The higher the flash ratio, the bigger is the influence of the moveable flash gap. The moveable flash gap is designed as a flash brake of a height of 2 mm. Its usage lead to differences in height of the parts up to 4.5 mm, which correspond to 16.6% of the parts volume, compared to parts forged with a fixed flash land. If the forging temperature is decreased from 1200°C to 1000°C, the influence of the moveable flash gap is reduced. The average differences in height are about 0.5 mm (about 3%). © 2015 Elsevier B.V. All rights reserved.

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