Presentation of a Novel “Simultaneous Three Axis Turning” Process for Time and Cost Efficient Machining of Rotational Symmetric Turbomachinery Components

摘要

In this paper a turning process is presented which is enhanced by a third tool movement axis. Besides the two already existing translational X- and Z-axes an additional rotational axis is added to the process. This is realized by integrating the already existing but yet unused B-axis of 5-axis turn-/mill-centers into the turning process. By moving the B-axis simultaneously during turning operations it is possible to adapt the tool/ workpiece engagement arbitrary to the individual machining case. Thus, the flexibility and the efficiency of turning can be increased significantly. This gives major benefits regarding tool consumption and machining time when turning geometrical complex parts made of hard to machine materials such as turbomachinery components. To gain a basic understanding of simultaneous three axis turning it is investigated which effect the additional tool movement has on the turning process regarding uncut chip parameters, process forces and tool wear development. Process parameters of the B-axis like rotational speed, rotational range and direction of rotation are varied. It is shown that the uncut chip geometry in three axis turning differs from the geometry in conventional turning. Especially the rotational speed and the direction of rotation have a major effect on the shape and size of the uncut chip. Besides this, the process forces are also affected by the B-axis movement. While the process forces are constant in conventional turning, these alter over time in three axis turning. It can be observed that the process forces are significantly shifted towards higher and lower levels in dependence of the rotational speed and direction. This effect increases with decreasing tool cutting edge angles. However, the influence of the B-axis movement on the tool wear is also investigated. It is shown that the tool wear can be distributed arbitrarily over the tool edge by changing the position of the B-axis. Thus, the tool life can be more than doubled.