Investigation of deviations in SI-engine behaviour due to manufacturing tolerances in cylinder heads

Cast engine components are experiencing ever tighter tolerance requirements and at the same time a more complex cast design. The geometries, some of which are inaccessible, are tested for quality assurance on the basis of relevant component characteristics, among other things. The position check measures the actual position of a feature in a spatial dimension. Information about the alignment and geometry of the combustion chamber cannot be derived from the measurement methods applied. The use of three-dimensional measuring methods, e.g., imaging by computer tomography, can additionally record the spatial component position and the component geometry. Further measurement data can be derived from this, which serves to increase process reliability and component quality, and to increase component quality within an entire component batch. On the one hand, the cylinder head limits the working space by the roof of the combustion chamber, on the other hand, the cylinder head has a significant influence on the charge movement, especially at the beginning of the intake flow, due to the geometry of the intake ducts. On account the high demands of modern gasoline engines with tumble combustion process paired with Miller operation at partial load, variable timing, etc., mixture formation is important for efficient operation. Mixture formation in air- and wall-guided combustion processes depends on the components air duct and injection. From the point of view of cylinder head production, the mixture formation component air guiding is an elementary development approach for implementing efficient and sustainable component production while ensuring component properties. From this, the question can be derived as to what influence, for example, different dimensional tolerances in the combustion chamber size have on engine operation. To address this question, 3D simulations and physical test bench measurements were performed. With a variation of the above-mentioned intake duct and combustion chamber geometries and due to manufacturing tolerances, simulation results and measurement data were evaluated, analysed and presented in this paper. The influence of manufacturing-relevant tolerance deviations in the early process step of cylinder head production on combustion engine operation can be recognised in different ways.

Influence of the stiffness of machine axes on the formation of wrinkles during rotary draw bending

This study presents that finite element (FE) simulations of rotary draw bending are improved by taking into account the stiffnesses of the machine axes. The results show the influence of the axis stiffnesses of the bend die, the wiper die, the pressure die and the mandrel on the formation of wrinkles at the inner tube bend. For this purpose the axis stiffnesses are varied in FE-simulations and wrinkle evaluation factors of the final components are determined and compared. Low axis stiffnesses correspond to large axial displacements when force is applied and cause greater wrinkle formation. In addition, practical tests are carried out on the machine to measure the axis displacements and associated forces. The resulting axis stiffnesses are entered into the FE simulation. The final geometry of the bending component of the FE simulation is compared with the geometry of a component produced in a practical test. The consideration of the axis stiffness in the calculation in contrast to ideally stiff axes provides wrinkle heights that are closer to the wrinkle heights in the practical test. The knowledge gained improves the prediction of the component quality and allows the evaluation of axis displacements measured on bending machines. The overall aim of the project is to react to machine-specific axis stiffnesses in the form of process control.

AM-Serienproduktion für die Automobilindustrie/AM series production for the automotive industry

Die additive Fertigung schafft neue Gestaltungsfreiheiten. Im Rahmen des Prototypenbaus und der Kleinserienproduktion kann das Verfahren des selektiven Laserschmelzens genutzt werden. Die Verwendung in der Serienproduktion ist bisher aufgrund unzureichender Bauteilqualität, langen Anlaufzeiten sowie mangelnder Automatisierung nicht im wirtschaftlichen Rahmen möglich. Das Projekt „ReAddi“ möchte eine erste prototypische Serienfertigung entwickeln, mit der additiv gefertigte Bauteile für die Automobilindustrie wirtschaftlich produziert werden können. Additive manufacturing (AM) offers new freedom of design. The selective laser-powderbed fusion (L-PBF) process can be used for prototyping and small series production. So far, it has not been economical to use it on a production scale due to insufficient component quality, long start-up times and a lack of automation. The project ReAddi aims to develop a first prototype series production to cost-effectively manufacture 3D-printed components for the automotive industry.

Software Component Quality Model

In Component Based Software Development (CBSD), applications are built from existing components either by assembling or replacing software parts. Reusing components may lead to faster software development and subsequently reduce cost and provide higher product quality. In CBSD, software component models define what components are and how they compose. However, no research has been done to assess the quality of software component models, to assess the characteristics of software component design. This paper proposed a software component quality model specifically to answer the question what characteristics make good component. A Systematic Literature Review (SLR) has been conducted by defining a robust protocol that combines automatic searches from different sources. The finding of the SLR has contributed to the development of quality model for CBSD, i.e. a proposed component quality model with metrics which is specific to software component design.