Abstract

Regeneration is a major mechanism to generate self-excited chatter vibration in cutting. Variable helix cutters are useful to suppress regeneration. Although simultaneous optimization of pitch/helix angles is significantly important, there is no practical design methodology to optimize the variable helix cutter geometry so far. In order to attain robust regeneration suppression, a new design method of variable helix cutters is proposed in the present study. The pitch angles vary along axial position due to disagreement of the helix angles. Because of this nature, regeneration can be suppressed in a robust manner with respect to changes of chatter frequency and/or spindle speed. The proposed design satisfies robustness against axial depth of cut variations. Optimal pitch/helix angles are formulated on the basis of distinctive relationship between the cutter geometry and “Regeneration Factor (RF)”, which is an index to quantify influence of regeneration in the process. Through analytical investigations, it is confirmed that regeneration can be suppressed effectively by the proposed method, resulting in significant chatter stability increase. Low immersion milling experiment verified significant stability and robustness of the proposed variable helix design.

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