Christoph Löpenhaus

Development of a Cutting Force Model for Generating Gear Grinding

One key component of powertrains is gears which are used in a continuously increasing quantity with improving quality. A productive process for finishing gears is the generating gear grinding process. The process is used mainly for large-batch production of small or mid-size gears after case hardening, especially in the automotive sector.Currently, the knowledge regarding the generating grinding process is limited and research is based mostly on empirical studies. The reasons for this are complex contacting conditions as well as the undetermined interactions between various process parameters.This paper focusses on current questions about generating gear grinding such as new approaches for a simulation based process design in consideration of cutting forces as well as the changing contact conditions.Copyright

Simulation des Maschinen-Verhaltens einer Verzahnungshonmaschine in MATLAB: Eine Methodik zur Umsetzung

Kurzfassung Das Verzahnungshonen ist ein Hartfeinbearbeitungsverfahren, das zum Beispiel in der produktiven Großserienfertigung von Zahnrädern für die Automobilindustrie eingesetzt wird. Hierbei ist die vollständige Ausnutzung der theoretischen Leistungsfähigkeit der Maschinen anzustreben. Dies wird jedoch durch das Auftreten selbsterregter Schwingungen und dadurch entstehende Abweichungen von der geforderten Verzahnungsqualität behindert. Daher wird am WZL der RWTH Aachen untersucht, wie die Stabilität beim Verzahnungshonen vorhergesagt werden kann. In diesem Beitrag wird ein Ansatz zur Simulation des Maschinenverhaltens einer Verzahnungshonmaschine vorgestellt.

Experimental analysis of the dynamic noise behavior of a two-stage cylindrical gearbox

There are several objectives in the design phase of gears: Besides a sufficient load capacity and a high efficiency of the gearbox, the acoustic behavior has to be taken into account. For a single-stage gearbox, several research projects have been carried out regarding the improvement of the noise behavior. Because of the mutual interactions between the gear meshes at a multi-stage gearbox, the knowledge at single-stage gearboxes cannot be transferred without restrictions. In this report, experimental investigations are carried out on a two-stage test gearbox. The experimental tests are analyzed by means of the stiffness of the intermediate shaft and the number of teeth of the two gear stages. The noise generation process will be investigated by the measured signals along the machine acoustic noise generation process. First, the excitation behavior of the gear mesh is analyzed by the detected rotational acceleration using angular rotation measurement systems. Subsequently, the transfer path between the gear meshes is determined to evaluate the mutual interactions between source and receiver. Based on the results, a guideline will be provided which stage has to be focused during the design phase.

Assessing the heterogeneity of residual stress for complementing the fatigue performance comprehension

The residual stress analysis is a well-established method for predicting fatigue failures of mechanical components. Within industrial constraints, the X-ray diffraction is a technique usually applied to measuring a small spot of the workpiece surface. This punctual and averaged outcome does not allow the proper representation of the residual stress. The objective of this study is to define a feasible method for assessing the heterogeneity of the surface residual stress state. The proposal is based on the theoretical relationship between the deviation of the residual macrostress and the intensity of the microstress. Steel shot peened gears were produced and their microstresses were assessed by means of the diffraction profiles broadening. The reference database was composed of topography measurements, metallographic analyses and residual macrostress maps. The stress heterogeneity was reasonably correlated to the intensity of the Gauss integral breadth. Applied to ground parts, the correlation’s parameter filled a comprehension gap between the measured residual stress intensity and observed contact fatigue failures. Using the same data from the macro residual stress measurement, the method proved to be feasibly applied. Moreover, by providing a deviation perspective to the residual stress state, the heterogeneity assessment enhances the analysis of a fatigue failure.

Influence of the metalworking fluid on the running behavior of gear analogy test parts

Boundary layers protect tooth flanks from solid-state contacts and, therefore, influence friction and wear. The characteristics of boundary layers (e.g. structure, chemical composition) and the running behavior of gears are determined by the manufacturing process (Klocke and Broeckmann in Prod Eng Res Dev 8(461):468, 2014; Brecher et al. in Prod Eng Res Dev 7:265–274, 2013). In this paper, the influence of the grinding fluid on the modification of boundary layers is shown. Analogy test parts are manufactured with varying fluids and additives. The differently ground test parts are measured regarding their boundary layer properties. Furthermore, the effects of the different resulting boundary layers on the running behavior are evaluated in finite life fatigue testing (pitting) on the two-disk test rig. By combining both measurement and test results, possible correlations between manufacturing and operation are investigated to establish a more sustainable and economical design of gears.

Influence of Tool Specification and Machining Parameters on the Wear Behaviour at Generating Gear Grinding

One research objective for generating gear grinding is to increase economic efficiency and productivity of the process. At the same time gear quality must be equal or higher. In addition to machining parameters, tool specification has a significant influence on process productivity, workpiece quality and the wear of the tool itself. Due to the variety of tool specifications process users have the problem of selecting the best fitting tool for their demands. Therefore, it is necessary to know how interactions of tool specification and machining parameters influence tool wear and workpiece quality. But basic experimental studies, which take different tool specifications into account, are missing today.This paper focuses on the influence of different tool specifications and machining parameters on the tool wear for generating gear grinding. With analogy trials the influence of different specifications and machining parameters on tool wear and the process is mapped. The results are analyzed, discussed and summarized in a model. Furthermore, the applicability of the findings based on analogy trials to generating gear grinding is validated.