Proposed in this thesis are 1) a global strategy for mold-cavity rough-cut machining, 2) a pocketing toolpath generation method using 2D cutting-simulation, and 3) a guide surface based toolpath generation method for high-speed machining.
For mold-cavity rough-cut machining, the cavity volume is sliced into a number of cutting-layers by horizontal cutting-planes and each layer is pocket-machined using the contour-parallel offset method in which the tool-paths are obtained by repeatedly offsetting the boundary-pocketing curve. The two stage rough-cut machining consisted of rough pocketing and finish pocketing stage is generally used in mold-cavity rough-cut machining because most of row-stocks entered to molds shops are roughly pocket-machined in a outside supplier shop. The minimum number of drill-holes to be required for rough-cut machining is determined from the global die-cavity shape which is estimated from outer boundary pocket curves on each layer and the drill-holes are located at the points which have the total minimum distance from its location to the machining starting points on each layer.
The major challenges in 2D pocket machining include: 1) finding a method for obtaining the boundary-pocketing curve, 2) generating evenly spaced contour-parallel offset tool-paths, 3) detecting and removing uncut-regions, and 4) estimating chip-loads for an adaptive feed control. No systematic solution for these problems has been offered in the literature, except the offset curves. Presented in the thesis is a straightforward approach to pocket machining, in which all the four challenges are handled successfully by using the existing cutting-simulation methods.
The last part of the thesis is devoted to a new tool path generation method based on the guide surface, which takes the machining regions into consideration as well. The guide tool paths, which are parametrically defined on the guide surface directly constructed from the machining regions, are projected onto the ITO (inverse tool offset)-surface. The proposed method is also applied to generating spiral tool paths and helical tool paths which can be used for high-speed rough-cut machining.
