The varying related material removal rate during deep grinding of cemented carbide end mill cutters results in an unevenly wear of the grinding wheel. This study therefore presents a simulation-based model for the load-adjusted design of grinding wheels to achieve balanced radial wear, as well as an evaluation of this model. The related material removal rate along the width of the grinding wheel is determined by a Dexel based material removal simulation for different end mill geometries. Based on these results an equation is derived to adapt the abrasive layer properties to the local load differences. Three grinding wheels with different types of gradients are then manufactured by a grinding tool manufacturer based on this equation. These and two grinding wheels with constant abrasive layer properties are used for deep grinding of ten end mills each. Afterwards the radial wear of each grinding wheel is measured by a confocal microscope. An analysis of the cutting edge chipping is done to evaluate the influence on the graded grinding wheels on the cutting edge quality. It was found that a reduction of the wear difference over the grinding wheel width of 52% and an improved cutting edge quality can be achieved by using graded grinding tools. This allows the time intervals between dressing steps to be increased without compromising the accuracy of the grinding process, thus also increasing its productivity. Finally, this article shows that the presented model allows for a more balanced wear behaviour, but has to be extended by considering further factors influencing radial wear.
Grinding the flutes of cemented carbide end mill cutters results in high and uneven radial wear of the grinding wheel. This is a consequence of the varying geometrical contact conditions over the grinding wheel width. Decreased manufacturing accuracy regarding the tool target geometry is the consequence. To compensate for this, the dressing intervals must be shortened. High non-productive times and an additionally reduction of the grinding layer results from this. The higher non-productive times reduce the productivity of the grinding process and, in conjunction with the shorter lifetime of the grinding tool, thus increase the costs per work piece. It has already been shown that load-adapted grinding wheels can reduce uneven radial wear up to 50%. The adaptation of the wear behaviour to non-uniform engagement conditions causes non-uniform radial wear to occur again under uniform engagement conditions. Uniform engagement conditions occur during grinding wheel sharpening. Therefore, the present study investigates the influence of sharpening on the grinding tool topography. For this purpose, sharpening tests are carried out on four differently graded grinding wheels. For comparability, the tests are also carried out on two non-graded grinding wheels. In the present work, the surface parameters are evaluated with regard to their suitability for analysing the sharpening condition of graded grinding wheels. The grain protrusion derived from this is subsequently used for evaluation. For this, a dependency on the grain concentration is proven and the grain protrusions are shown over the grinding wheel widths. From this, sharpening parameters are determined that enable reproducible sharpening of graded grinding wheels.
Die Nutbearbeitung von Vollhartmetallfräsern ist durch variierende Eingriffsbedingungen gekennzeichnet. Daraus resultiert ein ungleichmäßiger Verschleiß der Schleifwerkzeuge. Dies bewirkt eine Reduktion der Formgenauigkeit und eine Standzeitsenkung. Durch eine simulationsgestützte, belastungsangepasste Auslegung eines Gradienten an die Schleifaufgabe kann das Einsatzverhalten deutlich optimiert werden. Für die gradierten Schleifscheiben wird ein gleichmäßigeres Verschleißverhalten und eine geringe Schneidkantenschartigkeit nachgewiesen. Deep grinding of cemented carbide end mills is accompanied by difficult process conditions. An unequal wear across the grinding wheel width is the result. That leads to a loss of precisions and limits the tool life. A simulation-based load optimized grinding wheel design can improve the operational behavior of these grinding tools. A more uniform wear behavior as well as a low chipping of the cutting edges due to the graded grinding wheels are demonstrated in this article.
The varying related material removal rate during deep grinding of cemented carbide end mill cutters results in an unevenly wear of the grinding wheel. This causes a reduced geometrical precision of the manufactured tools. Consequently, the intervals between dressing steps are reduced and the dressing infeed increases. The aim of this research project is therefore to design a tailored grinding tool with uniform wear behavior. To address this situation, the grinding tool load is determined simulatively along the width of the grinding wheel. From this an equation is derived to adapt the bonding layer properties to the local load differences. First investigations show that two different concentrations zones in the abrasive layer of the grinding wheel improves the wear behavior already. This indicates that a further reduction of the wear difference is possible by a more uniform gradient. A simulation is performed to define a knowledge based gradient with more than two concetration zones. This allows a more precise load optimized adaptation of the grinding layer properties to the geometry to be ground in terms of wear behavior. Grinding tools manufactured on this basis are used for flute grinding of end mill cutters. A reduction of the wear difference over the grindig wheel width of 52% and an improved cutting edge quality of these are demonstrated.
Aufgrund des ungleichmäßigen Verschleißes beim Nutentiefschleifen von Hartmetall-Schaftwerkzeugen sind bisher verkürzte Abrichtintervalle notwendig, um eine hohe Fertigungsgenauigkeit zu gewährleisten. Gradierte Schleifscheiben sorgen jetzt für optimierte Standzeiten und eine bessere Wirtschaftlichkeit.
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