Defects like folds can arise using forging for the production of long flat pieces made of aluminium. A special defect is the formation of inner folds. These can be seen in the grain flow. Inner folds have a negative effect on the dynamic properties of the forged part. As a production process, forging can be divided into single-directional and multi-directional forging. The formation of inner folds was observed at the single-directional forging. By using the multi-directional forging, a forming operation working from different directions, the forming can be set variably. Thus the development of folds can be prevented. A newly developed method can help in the selection of the forming process and in determining an appropriate tool geometry. Here especially the area is adapted, where the development of inner folds occur. Therefore a calculation model was developed. It integrates a computer-aided identification of the inner folds. Using this model, a correction of the parametrically constructed forging tool is possible.
multidirectional-forging, long flat pieces, aluminium, fibre orientation
The implementation of process monitoring technologies in manufacturing processes allows significant cost and time savings. An online process monitoring of die cavity filling in warm forging processes could not be realized until now. Important process parameters for example billet volume, billet temperature or lubrication could only be observed after forging. This paper describes the implementation of an online process monitoring system based on electricity.
forging, process monitoring
To produce preforms for complex long flat parts with an unsteady mass distribution along the longitudinal axis rolling processes, like cross wedge rolling, can be used. Tools for cross wedge rolling processes can be constructed as roller or flat, both with wedges. In the collaborative research project "SFB 489 - Process chain for the production of precision forged high performance parts" the subproject "Innovative machine and tool technology for precision forging" deals with the development of a flashless forging process for a two cylinder crankshaft with pin and flange. This process is developed by IPH - Institut für Integrierte Produktion Hannover. The first preform of the developed forging sequence is produced by a cross wedge rolling process on the basis of flat with wedges. To consider the mass distribution of the two cylinder crankshaft in the preform for a rolling process four mass concentrations for the crank arms and mass concentrations for pin and flange are needed.
crankshaft, cross wedge rolling (CWR), forging sequence, preform, rolling process
Lightweight design of cars is one way to reduce fuel consumption and increase the range of cars. This is an important factor to attain the EU limit values for CO2 emissions for vehicles and thus to avoid penalties for exceeding these limits as of the year 2012. The growing number of uses for high-strength steels or lightweight structures are adequate means to reduce weight. At IPH - Institut für Integrierte Produktion Hannover gGmbH a method to produce hollow profiles made of aluminum was developed. This method, called hydroforging, combines flashless forging and tube hydroforming. It allows the production of thick-walled hollow aluminum profiles with undercuts without the need for complex tool kinematics. The forging is supported by an active medium. A tool concept has been developed using the drives of a hydraulic press with die cushion. With this tool, various part geometries shall be produced and analyzed. To produce the tools' interior pressure and the forming pressure, liquid tin as an incompressible active medium is used. The forming is initiated by upsetting the aluminum profiles and supported by the active medium, so that the profile is pushed against the cavity of the dies. The process was designed based on simulations and will be verified by practical experiments. This paper describes the development of the forging process with an active medium.
hydroforming, forging, tubes, aluminium, FEA
Cross wedge rolling is a method for reshaping cylindrical billets for getting a better mass distribution. Against the backdrop of rising material costs, this method is increasingly becoming the focus of many forging companies - but the high investment costs for tools and equipment prevents the economical benefit of the process. With flat cross wedge tools and corresponding rolling machines tooling costs can be reduced and the process is therefore interesting for small batches. Moreover, studies show that CWR is also applicable in warm temperature range.
warm forging, process chain, cross wedge rolling
In this paper the development of the new production technology hybrid forging is described. Hybrid forging combines forming of bulk and sheet metal-elements including joining. Therefore the classification of hybrid party by material and by the type of the semi-finished product is discussed. In addition, the benefits of hybrid parts are explained. In experimental forging tests with simple geometries a cylindrical bulk part was joined positively with a sheet metal by form closure. A material bond was only partially achieved.
hybrid, forging, sheet metal forming, joining technology, steel, adhesive bond
Multi-directional forging enables flashless preforming for complex workpiece geometries by a cross-section formation and mass distribution in one forging stroke of the press. The process principle is based on a tool with multi-directional acting forming punches. In addition to the vertical forming by a punch a horizontal deformation is performed by horizontally arranged sliders. The drive of the sliders is performed by a redirection of the ram movement using wedges. The multi-directional forging has been studied and developed further over the past decade in a number of research projects. Starting with simple flashless, flat preforms for connecting rods made of steel, the technical feasibility of this method has been demonstrated. In subsequent steps, the principle has been transferred to crankshafts. As part of the Collaborative Research Centre 489, the crankshaft was broken down to a unit cell in order to investigate the fundamental transformation of the bearings and the crank webs. With this knowledge, forging sequences for simplified single and two-cylinder crankshafts were designed (without secondary form elements). Currently the forging sequence for a full two-cylinder crankshaft is designed with secondary design elements. The interaction of the mass distribution by cross-wedge rolling and multi-directional forging is analyzed. The flashless forging of two-cylinder crankshafts with such complicated geometries and corresponding necessary material flow is only possible using a multidirectional preforming. Finally, the applicability of the method to aluminum was investigated in the context of a DFG project – again based on a flat part long preforms. Here particularly clearly the limits of the process could be shown. Various forming directions were combined. With some of these combinations flash developed during the forming operation. Others have shown to be usable for a flashless preforming of complicated geometries.
multidirectional forging, flashless, preforming, cross-wedge rolling, connecting rod, crankshaft, st
To overcome the geometrical limitation of warm forging, in the European research project "DeVaPro - Development of a Variable warm forging Process chain" new rolling and forging processes are developed. The aim of the project is to develop a warm forging process chain by selecting the best suitable hot preforming technology to obtain the desired mass distribution before warm forging. The technology will be adapted to the specific requirements of warm forming. A warm rolling operation and an induction reheating process will be introduced within this project. A steering link and a connecting rod are used as sample parts.
warm forging, process chain, cross wedge rolling
