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The impacts of various thermo-mechanical process routes in forming of EN AW 7075 alloy on mechanical properties, microstructure and corrosion resistance were investigated. A simulated forming process of two very different conditions, i.e., T6 and W-Temper is the focus of the present study. Irrespective of soaking time and pre-deformation, specimens quenched in water exhibited superior mechanical properties compared to air-cooled ones. Shorter solution heat-treatment soaking time in the pre-deformed condition, i.e., T6-Temper, caused a drop in the elongation at fracture. Microstructural analysis revealed, regardless of pre-deformation and soaking time, a high fraction of fine η′ strengthening precipitates with stoichiometry close to MgZn upon artificial ageing in the specimens quenched in water. Mechanical properties and microstructural evolution indicate that pre-deformation of solution heat treated specimens before the ageing treatment, i.e., W-Temper, leads to dislocation multiplication and, eventually, further nucleation sites for precipitation. Thus, forming the W-Temper condition caused very similar resulting mechanical properties and microstructure compared to that of T6 condition. However, W-Temper forming was found to be detrimental for the stress corrosion cracking. Corrosion behaviour of air-cooled specimens was found to be very poor in general. Results obtained in the present work can facilitate the development of thermo-mechanical process routes for EN AW 7075 to eventually tailor mechanical properties, corrosion behaviour and microstructure.

Bending and other manufacturing processes are subject to uncertain process conditions like varying properties of the semi-finished parts. In order to obtain precise bending angles, these variations have to be compensated. Upstream processes often deliver valuable information about the actual part properties. This paper presents a blanking-bending process chain in which information from the blanking process is passed on to the bending process. A feed-forward bending controller uses this information as input state and compensates deviations from the nominal state. In a second instance, a closed-loop controller addresses model uncertainty of the feed-forward controller as well as unknown disturbances. A model-based closed-loop control design is shown which increases stability, stationary accuracy and time-optimality.

In sheet metal forming, the fixation of tools in presses has not been considered to be variable for process optimization yet. Every clamping point fixes the tool. Tool areas without a fixation point have a vertical degree of freedom, respectively. Against this background, it seems to be evident that the kind of tool fixation can influence its static and dynamic beahviour. In shear cutting processes, tool vibration is an important phenomenon, as it affects tool wear on the one hand and influences part quality on the other hand. In this paper, a methodology for influencing the tool vibration by specific setups of the clamping situation is introduced.

Stringer sheets are bifurcated parts that possess, compared to flat sheet metal parts, a higher stiffness due to their higher geometrical moment of inertia. Currently, the common way of forming spatially curved stringer sheets is hydroforming. This article shows the feasibility of forming stringer sheets by using solid tools with short process times, which is more relevant for the industrial application. A die-bending process with a slot in the punch for the stringer is investigated. Since buckling of the stringer is one of the occurring failure modes, depending on the stringer height, an analytical estimation of the critical stringer height is carried out while considering the bending angle, bending radius and sheet thickness. The subsequent numerical and experimental investigations show a good agreement with the analytical estimation. Finally, a stiffness test is carried out with stringer sheets of different stringer heights. The result of this test underlines the motivation of forming buckling-free stringer sheets with stringers as high as possible. The normalized stiffness increases with rising stringer height until buckling occurs. At this point the stiffness values begin to fall with growing stringer height.

Load carrying mechanical structures like trusses face uncertainty in loading along with uncertainty in their strength due to uncertainty in the development, production and usage. The uncertainty in production of function integrated rods is investigated, which allows monitoring of load and condition variations that are present in the product in every phase of its lifetime. Due to fluctuations of the semi-finished parts, uncertainty in governing geometrical, mechanical and electrical properties such as Young's moduli, lengths and piezoelectric charge constants has to be evaluated. The authors compare the different direct methodical approaches Monte-Carlo simulation, fuzzy and interval arithmetic to describe and to evaluate this uncertainty in the development phase of a simplified, linear mathematical model of a sensory rod in a consistent way. The criterion to compare the methodical approaches for uncertainty analysis is the uncertain mechanical-electrical transmission behavior of the sensory rod, which defines the sensitivity of the sensory compound.

The market pressure and the products of competitors are decreasing the duration of product life cycles. Besides that, special customer requirements and rising product complexity result in an increase of the effort and the costs of the development process. In order to minimize the effort of the development process as well as to handle the uncertainties which come along with the planning and selection of manufacturing systems a data-based configuration tool was developed for the use in the field of sheet metal forming. Based on the product data of existing press systems, the tool is able to predict the fundamental configuration of a newly developed press system. The utilization and functionality of the tool is illustrated on two exemplary press systems.

Uncertainty in the properties of semi-finished parts can cause fluctuations in the product properties, especially if they have a strong effect on the process and cannot be compensated by process adjustments. Incremental forming processes have the potential to react to changing conditions by adapting the tool movement during the process. This paper analyzes the feasibility of controlling material flow in an orbital forming process in order to selectively fill those geometric elements which were specified with narrow tolerances by the designer. The effect of different process parameters on the mushroom effect and the degree of mold filling are analyzed by FEM simulations and experiments. In order to realize online monitoring and control, an estimation model is introduced, which maps signals from sensors and the process control to the geometric target values.

The magnetic hardening of ARMCO® and FeCo17 in a severe plastic deformation and an incremental forming process is presented. The enhancement of the coercivity, which depends on the strain induced by the forming process, is investigated. Strain induced during the incremental forming process are analysed in FE-simulations.

In metal forming a trend is observed towards increasing the performance of products by means of functional integration. One approach being pursued is the integration of electronic components. Multifunctional profiles with electrical conductors can transmit data and energy in addition to the mechanical function. They can be produced efficiently by roll forming. During the roll forming of multifunctional profiles wrinkles and cracks in the conductors may occur in the area of the contact of the rollers due to the contact normal stresses. In this paper, a design approach for multifunctional profiles preventing these failures in the tool contact area is presented and discussed on the basis of experimental and numerical investigations.

The application of environmentally benign tribological systems becomes more and more important in cold forging operations. However, questions regarding the performance of these systems still oppose a widespread use in industry. Due to severe loads in cold forging, high tool temperatures of up to 200°C may occur as a result of forming energy and friction in combination with a high output in a short range of time. The temperature at the tool–workpiece interface is even higher, though an exact identification proves to be difficult. Former investigations regarding the influence of the relative velocity indicated that the occurring temperatures are primarily responsible for the decrease of the friction. The paper at hand presents the results of a systematic investigation of the influence of the temperature at the tool–workpiece interface on the performance of environmentally benign tribological systems.

Continually increasing exhaust emission standards for automobiles and an increasing environmental awareness push design engineers to develop new constructive and material concepts. So-called sandwich panels, consisting of stiff facings and light-weight cores, offer the possibility to combine properties of different materials synergistically. When processing large quantities, as is the case in the automotive industry commonly used manufacturing processes for cutting sandwich panels, like sawing or milling, are not applicable. A common manufacturing process to cut metal sheets in high quantities is shear cutting. However, pre-trials of shear cutting of sandwich panels have shown that it is not possible to achieve flawless cutting surfaces with current process layouts. Characteristic types of failure like high bending of the facings, delamination effects, burr formation and an undefined cracking of the core material were ascertained. Thus, in this study, the influence of cutting parameters, such as the clearance and the punch diameter, on these types of failure is examined. Five different clearances between 0.025 mm and 0.4 mm with two punch diameters, 8 mm and 32 mm, were investigated. In order to compare the influence of different materials, three commercially available sandwich panels were studied. The chosen sandwich panels differ both in the face sheet thickness and the core material. Finally, the shear cutting force is measured to identify a possible correlation between the cutting force and the face bending. As a result, optimal clearances to minimize the face bending are derived. Additionally, the influence of the core stiffness on the cutting force is determined.

So far, determining the necessary precut dimensions of metal sheets prior to bending has been an unsolved question. During the last decades numerous calculation methods have been suggested. However, comparing these different methods indicates that different calculation methods suggest diverging precut dimensions. Especially in roll-forming, where multiple bend operations occur within the same bend part, these differences between several calculation methods can add up to some millimetres. The accuracy of presently available methods can hardly be compared. Thus an optimized method is needed. One possibility to determine the initial sheet width is identifying the position of the unlengthened layer in the bend zone. This study compares the position of the unlengthened layer determined in experiments and numerical simulations for different bend geometries and materials. The results indicate that even state of the art measuring technique is not accurate enough to determine the position of the unlengthened layer properly. Due to high measurement uncertainties, numerical simulations are required to assess the influence of geometry or material parameters on the position of the unlengthened layer. However, combining numerical and experimental results shows that the geometry of the bend part influences the position of the unlengthened layer and thus the required precut dimension. In contrast, a significant influence of material strength on the position of the unlegthened layer was not found.