Applied Mechanics and Materials Vol. 794

Abstract: This paper presents a method with whose help it is possible, to quickly and precisely predict the influence that thermal spot-shaped joining processes has on the dimensional stability of complex component structures even in early planning phase. The welding distortion is calculated in the context of reduced computing time, based upon an experimentally calibrated mechanical substitute model. This expands existing approaches of substitute models and defines both an experimental and numerical procedure for creating adequate calibration samples. In turn, this makes use of the potential obt ained for standardizing the experimental basis for calculating and modelling the distortion to automatically carry out painstaking calibration processes in simulations and experiments in future based upon mathematical model functions. Finally, the limits to applying the substitute spot welding model are verified with reference to its predictability using a complex joining situation of a car body construction.

Abstract: Lithium-ion batteries have been the dominant energy storage technology in consumer electronics for several years and meanwhile advanced into e-mobility and stationary applications. The trend towards large-scale batteries presents manifold challenges to production technology. One decisive assembly process is filling electrolyte liquid into the battery case. This paper discusses the main influences and challenges for production technology concerning this crucial manufacturing process and how they are addressed. First preliminary results are presented.

Abstract: The electrification of drives is an enormous challenge as well as an opportunity for the automobile industry and its suppliers to provide competitive and affordable technologies to participate within this change. The high costs of battery systems, the range limitations of electric vehicles and the insufficient charging network are three of the main reasons, this change is still troublesome in its realization. To realize a cost-efficient production of battery systems, a high degree of automation and an increased production throughput is necessary. This paper focuses on the pouch cell with its high energy density and presents a solution, of how to significantly increase the production throughput in the z-folding of separators. The approach pursued is the assessment of shifting from discrete pick-and-place operations to a continuous process flow, enabling a cost-efficient production of electrode-separator compounds and ultimately lithium-ion batteries.

Abstract: The use of industrial grippers induces to deal with the system grippers are embedded in. Besides the gripper this includes the environment, the handling device the gripper is attached to, the task the gripper should perform and the part to be handled. All this domains form the system handling. The paper analyses this system using different methods of the field of structural complexity management. Objective is to identify the most important and most influential factors governing the system.

Abstract: Modern day production has to overcome a polylemma – the gaps between economies of scale and scope as well as between economies of plan and value. Due to shorter product lifecycles and a rising demand of customization, flexibility and adaptability of assembly processes will become key elements for a sustainable success of industrial production in high-wage countries. Self-optimization as presented in this paper has been identified as one major contributor to the enhancement of this flexibility and adaptability. After a short introduction of the historical background, the specifics of the application of self-optimization to assembly are discussed using its meta model. In the end, two application examples are presented to illustrate its industrial deployment.

Abstract: The global competitive situation and change to customer market results in shorter product life cycles and high variant diversity as a consequence of customization. Especially in assembly systems the increasing complexity forces manufacturing companies to enhance their flexibility. In manual assembly systems the worker and the use of his cognitive skills provide the required flexibility and knowledge to perform the assembly process efficiently. The presented approach deals with an integrated technology management concept for manual assembly. Thereby, a special focus is set on support technologies which are aimed to support the cognitive skills of the worker. In the first step useful technologies have to be identified on the base of a specific search strategy. As soon as a potential technology is identified, the technology investigation starts. Core element in the concept is an impact analysis to assess the benefit of new support technologies in a specific manual assembly system.

Abstract: Lubricants in sheet metal forming have to meet increasing demands resulting from political aims and ecological requirements. For that reason, industry aspires the reduction of lubrication with the long term goal of replacing conventional mineral oil based lubricants entirely. Dry metal forming to a certain limit can be achieved by using liquid CO₂ during the forming process. This lubricant vaporizes after deep drawing process and leaves a clean work piece that can be used in coating or joining processes without any subsequent cleaning. In this contribution, further development and resulting effects of numerous process parameters are evaluated and presented. Investigations of restraining forces in strip draw tests when lubricated with liquid CO₂ include different tool parameters like drilling diameters (120 and 140 µm), different numbers of drillings (25 and 49) as well as different process parameters like surface pressure (2,5 and 6,5 MPa) or drawing speed (50 and 100 mm/s). Amount of restraining forces in this paper also are compared to two different conventional mineral oil based lubricants (Wisura AK 3080 and Wisura ZO 3368). The results presented in this contribution may provide a better understanding of tribological mechanisms emerging within this new lubrication system.

Abstract: Lightweight sandwich sheets represent an alternative in the framework of body lightweight construction. They are made of metal face sheets which form a shear-resistant bond with the thermoplastic core layer. The present work describes the drawbead behavior of sandwich sheets and how it can be modelled in a numerical simulation. Drawbeads are used to control the rate of material flow into the die cavity and are located in the binder area. In the numerical simulation they are either modelled as physical drawbeads or replaced by an equivalent drawbead in which a certain drawbead restraining force (DBRF) is specified as a boundary condition. The values of DBRF can be obtained in a strip test, via numerical simulation or predicted with the aid of a drawbead model. In the current study, strip tensile tests through different physical drawbeads are conducted for sandwich materials. With the obtained variables, restraining forces and thinning values, the results from numerical simulations can be evaluated. Once an optimal simulation approach is found, a parameter study can be conducted to analyze the main influencing factors on drawbead behavior. The results from this study can be leveraged to create a semi-empirical drawbead model.

Abstract: This paper provides results from experiments to improve formability of DP 1000 steel in forming a complex profiles in single point incremental forming with induction heating. High attention is rewarded to the straight effect of induction power and tool settings, in order to determine if the heating temperature is sufficient for raising the formability. The steel sheet is formed by a punch in the upper side and synchronized by induction heating for the sheet on the lower side. Investigations show a maximum achievable wall angle of 70°, which was accomplished at 20 kW induction power for the two formed shapes pyramid and cone. The operational efficiency improved by reducing both the forming time and the induction power required obtaining an optimum heating temperature for the sheet blank. The presented method can be used to increase the formability of difficult-to-form metals by using a simple setup.