Sebastian Schumann

Modelling, simulation and experimental investigation of chip formation in internal traverse grinding

We present recent developments in modelling and simulation of internal traverse grinding, a high speed machining process which enables both a large material removal rate and high surface quality. We invoke a hybrid modelling framework, including a process scale model, simulations on a mesoscale capturing the proximity of a single cBN grain and an analysis framework to investigate the grinding wheel topography. Moreover, we perform experiments to verify our simulations. Focus in this context is the influence of the cutting speed variation on the grain specific heat generation.

Modelling and simulation of Internal Traverse Grinding: bridging meso- and macro-scale simulations

Abstract In this work, we focus on the computational bridging between the meso- and macro-scale in the context of the hybrid modelling of Internal Traverse Grinding with electro-plated cBN wheels. This grinding process satisfies the manufacturing industry demands for a high rate of material removal along with a high surface quality while minimising the number of manufacturing processes invoked. To overcome the major problem of the present machining process, namely a highly concentrated thermal load which can result in micro-structural damage and dimension errors of the workpiece, a hybrid simulation framework is currently under development. The latter consists of three components. First, a kinematic simulation that models the grinding wheel surface based on experimentally determined measurements is used to calculate the transient penetration history of every grain intersecting with the workpiece. Secondly, an h-adaptive, plane-strain finite element model incorporating elasto-plastic work hardening, thermal softening and ductile damage is used to simulate the proximity of one cBN grain during grinding and to capture the complex thermo-mechanical material response on a meso-scale. For the third component of the framework, the results from the preceding two simulation steps are combined into a macro-scale process model that shall in the future be used to improve manufacturing accuracy and to develop error compensation strategies accordingly. To achieve this objective, a regression analysis scheme is incorporated to approximate the influence of the several cutting mechanisms on the meso-scale and to transfer the homogenisation-based thermo-mechanical results to the macro-scale.

Modelling and Simulation of Internal Traverse Grinding—From Micro-thermo-mechanical Mechanisms to Process Models

This contribution deals with the modelling and simulation of Internal Traverse Grinding (ITG) using electroplated cubic Boron Nitride (cBN) wheels. This abrasive process fulfils the industrial demands for an extensive rate of material removal along with a good surface quality while minimising the number of manufacturing processes. To overcome one drawback of ITG in terms of a highly concentrated thermal load on the workpiece surface, a multi-scale simulation framework that combines different modelling methods in a hybrid framework is presented. In this context, a geometric-kinematic simulation is combined with a finite element analysis which focuses on the thermo-mechanical response of a single cBN grain being in contact with a hardened workpiece. Via a special scale-bridging scheme, the results of both the former simulations are used to compute a thermo-mechanical load compound acting as a boundary condition in a process-scale finite element model. The latter is then used to capture thermally induced geometrical errors during ITG and to develop compensation strategies accordingly.

Modellierung des Nassstrahlspanprozesses zur Präparation von Zerspanungswerkzeugen

KurzfassungDie Einrichtung von Nassstrahlspanprozessen zur Präparation von Schneidkanten erfordert ein hohes Maß an Prozesswissen und kommt aufgrund der komplexen Prozesssteuerung nicht ohne die Durchführung von Einrichtungsversuchen aus. Durch die Simulation des Nassstrahlspanens soll der Einrichtungsaufwand deutlich reduziert werden. Der folgende Beitrag stellt einen neuartigen Ansatz vor, bei dem der Materialabtrag beim Nassstrahlspanen zur Schneidkantenpräparation modelliert und die resultierende Schneidkantengestalt in Abhängigkeit der Strahldauer simuliert werden kann.AbstractCutting edge preparation via wet abrasive jet machining is a flexible but complex process. Experiments are often required when setting up new processes due to the complex control. The effort for setting up new preparation tasks can be distinctly reduced if simulating the preparation process in advance. In this article, a novel approach for the numerical simulation of the material removal at cutting edges is introduced considering the applied blasting time. The investigations show that a prediction of the resulting cutting edge shape is feasible.