Condition for machining feasibility for a five-axis machining center

Recently, five-axis machining centers with non-orthogonal rotation axes have been developed to achieve a high stiffness and large machinable area. Although such machine tools can expand the manufacturing field, adopting not only orthogonal axes, but also non-orthogonal axes, requires generalization of conventional form-shaping theory. Moreover, since it is not possible to imagine simultaneous five-axis movement of machine tools with non-orthogonal axes, it is important to analyze the validity of the developed machine tools with non-orthogonal axes using generalized form-shaping theory by a structure analysis method. In the present paper, generalization of the form-shaping function is first performed, and the conditions whereby machining centers with nonorthogonal axes can achieve every position and posture are clarified for an index showing the validity of the machine tool structure. Finally, the machining feasibility is verified for a machine tool structure with nonorthogonal axes using the derived conditions.