An optimisation algorithm for reducing the number of turns on space-filling curve toolpath for sculptured surface milling

摘要

The space-filling curve (SFC) toolpath is characterised as having shorter toolpath length and zero' number of tool retractions. It is especially suitable for machining workpieces with complex boundaries. Though it is also always criticised for the weakness of having many turns, the number of which is uncontrollable at the toolpath planning stage. This paper aims to reduce the number of turns on an existing SFC toolpath by merging the neighbouring u-turns. At first, the cutter contact (CC) net is constructed, with which the adjacent points of a given CC point can be accessed. Based on that, the u-turn recognition and merging methods are explained in details. Five cases of neighbouring u-turns are investigated. By merging a pair of these u-turns, two turns can be eliminated. The proposed turn optimisation algorithm is verified with several SFC toolpath examples. The results indicate that the number of turns can be reduced by 25-35% at the expense of a lower than 3% toolpath length increment. With the turn number decreased, the machining dynamics of the SFC toolpath can be improved.