H. Autenrieth

3D-FEM Modeling of Gear Skiving to Investigate Kinematics and Chip Formation Mechanisms

Latest research clearly demonstrates the excellent capability of the gear skiving process. For further improvement of the process and particularly for the enhancement of the process reliability fundamental scientific research is conducted. In this paper the result of investigation of process kinematics and chip formation mechanisms are presented. First the experimental analyses will be described, which represent an essential basis for developing and validating the models. In further experiments the material behavior of the test material SAE 5120 was determined and a material model was developed. The modeling of the process represents a central aspect of the research. This includes the basic modeling of the kinematics in a 3D-model. The simulation enables analysis of the kinematical conditions as well as the chip formation mechanisms and evaluation of the effects on process reliability. The results support the tool and process design and are an important basis for the implementation of the process.

Investigation of the Surface Characteristics for the Micro-Cutting Process with Finite Element Simulation

As the service life of components is significantly influenced by the surface layer properties, namely surface roughness, surface work hardening and residual stresses, these are the focus of many investigations. As these properties can be measured experimentally in many cases only after finish of the process, simulation models can be used to explain the final process results by the interpretation of the development of the result quantities during the loading and unloading state. The developed and validated simulation model and the extended process knowledge can be used afterwards to predict process parameter combinations with optimal process results for other cutting tool-workpiece combinations without performing large and costly experimental investigations. In the present study, the dependences of surface work hardening and residual stresses on process parameters of micro-cutting, namely cutting depth, cutting velocity and cutting edge radius are investigated by 2D finite element simulations using ABAQUS/Standard. The material behaviour of normalized AISI 1045 is described in dependence of strain, strain rate, and temperature. Chip formation is modelled by continued remeshing of the work piece. The simulation results are validated by the comparison with experimentally determined integral width and residual stress depth profiles, using x-ray diffraction method. The influence of the ploughing process, characterized by the ratio of cutting edge radius to cutting depth, on surface characteristics is well described by the simulation model.

Investigation of process specific size effects by 3D-FE-simulations

The miniaturization of cutting processes into the micrometer regime shows process-specific size effects like the nonlinear increase of the specific cutting force for decreasing cutting depth. In order to investigate these size effects, the mechanics of the material as well as the operation have to be investigated. A turning process was chosen to study the influence of process parameters like cutting depth h, cutting width b, cutting edge radii r, and cutting velocity v c on the specific reaction force by 3D-Finite-Element-Simulations for normalized AISI 1045. For an adequate numeric reproduction of the material behavior, a physically based rate-dependent plasticity law was used in combination with a failure criterion describing the material damage and chip separation. The characteristics of the influences of the different parameters were analyzed mathematically precisely by similarity mechanics. The characteristics of the chip shapes determined by numerical simulations were compared with experimental results and a good correlation was found. The finite element simulations were executed on the high end mainframe XC4000 for a significant improvement of the run time of the simulations.