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The power train of a modern servo-screw press with low rotational moment of inertia provides higher dynamics and a new kind of flexibility in forming and stamping processes compared to conventional servo presses. In this paper a new technology for deep drawing on servo-screw presses called cushion-ram pulsation is described. It uses superimposed low-frequency vibrations between 10 Hz and 50 Hz at the cushion and the press ram. For deep drawing operations, the high tensile stresses in the frame of cylindrical cup usually lead to a reduction of material thickness. Thus, and due to the lack of work hardening, fractures frequently occur in the punch radius. The process developed here shifts critical loads to higher drawing ratios by decoupling the drawing operation and the prevention of wrinkles. A high frequency of the cushion-ram pulsation is necessary to allow high productivity. Technological results will be increasingly determined by the machine.

Joining by forming of magnesium alloys is restricted by the limited forming capability of magnesium at room temperature. To form acceptable joints without cracks usually heating of the parts to temperatures of 220°C or more is required. The application of state-of-the-art joining by forming methods (such as self-pierce-riveting or clinching with a contoured die) implicates pre-heating times of at least 3-6 s to achieve joints of acceptable quality. A new joining by forming technology, that is working with a flat anvil as a counter tool instead of the contoured die shall be introduced in this paper. This new technology is offering important advantages especially in joining Mg/Mg, Al/Mg or Fe/Mg connections, most remarkably being the reduction of pre-heating times to less than 1 s, thus allowing for the fast and reliable joining of magnesium parts. Parameter influences on the formation of the connections have been investigated and the values for the tensile strength have been determined for a wide range of connections

In this study a numerical simulation model was designed for representing the joining process of carbon fiber-reinforced plastics (CFRP) and aluminum alloy with semi-tubular self-piercing rivet. The first step towards this goal is to analyze the piercing process of CFRP numerical and experimental. Thereby the essential process parameters, tool geometries and material characteristics are determined and in finite element model represented. Subsequently the finite element model will be verified and calibrated by experimental studies. The next step is the integration of the calibrated model parameters from the piercing process in the extensive simulation model of self-piercing rivet process. The comparison between the measured and computed values, e.g. process parameters and the geometrical connection characteristics, shows the reached quality of the process model. The presented method provides an experimental reliable characterization of the damage of the composite material and an evaluation of the connection performances, regarding the anisotropic property of CFRP.

Two new joining methods for sheet metal parts, dieless clinching and dieless rivet-clinching are introduced in this paper. With these methods all formable materials can be joined. Contrary to conventional technology in joining by forming these new methods are working with a flat anvil as a counter tool instead of a contoured die, which has a number of advantages. The process has become simpler, the process reliability is increased, misalignments of the joining tools don’t effect the quality of the connection anymore and even new applications, such as the joining of materials with a limited malleability become possible. Examples of realized connections and FE-calculations of the joining processes are presented.

The numerical forecasting of car body construction processes is already being used in industry to provide support in the ramp-up process. However, long calculation times are stretching the finite element method (FEM) to the limit, in particular when analyzing the effect of the variation of an input variable on one or more dependent variables. Moreover, there is still a need for experienced users to separate relevant from irrelevant parameters and to determine their variation. This paper presents a method that makes it possible, based on stochastic experimental design (DOE) in combination with both principle component analysis (PCA) and singular value decomposition (SVD), to create mathematical models that separate relevant from irrelevant input variables and that represent the effect of individual variables on all part or assembly areas by means of a variance-based sensitivity analysis. The method is verified in a case study based on realistic front hood geometry. The study examines the deep-drawing process steps as well as the geometrical accuracy in a measuring device. It is shown that it is possible to represent the effects of the most important variables from these processes on the strain and geometry parameters of the car body part and to vary these, based on a model function, interactively

Press hardening of steels for the production of car body components is very common. The reason for this is that the process allows the use of blanks with low wall thickness and the production of ultra-high strength components with complex geometries. The Hot Metal Gas Forming (HMGF) process for closed profiles combines the advantages of hydroforming, such as increased rigidity, functional integration or elimination of joining operations, with those of press hardening. In this paper results of continuous tests with actively cooled tools are presented in combination with temperature and displacement measurement. Furthermore, test results for HMGF with tool integrated conductive heating are demonstrated. Tests were done with tube material PHS1800 by SSAB, part temperatures over the Point of austenitisation and maximum internal pressure of 70 MPa. Thermocouples recorded the heat distribution in the tools. Other measured and recorded variables were the displacement of the component wall while forming under increasing internal pressure by a tactile displacement sensor and simultaneous temperature of its surface with a thermal sensor head. For the first time, information on pressure, the corresponding deformation stage and temperature profile could be documented during an entire forming step. A close to series production geometry DP4 was used to investigate the tool-integrated conductive heating of components.

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