工件加工面之製程需求表達

Abstract

本研究提出一個以CAD邊界表示工件模型的加工面可行加工規格方法，此方法稱為製程需求表達法是延續Wu & Liu (1991)所提出的研究。本研究所探討工件主要限定每個面為平面，每個加工面與加工面間彼此正交或平行。本研究考慮工件在某一進刀方向（cutter approach direction）下，必須遵循以下三大步驟；首先，每個加工面在決定投影面有以下三個限制：(1) 投影面與進刀方向呈現正交狀態、(2) 每個加工面所投影的結果至少要有邊線、(3) 所投影的加工面皆在投影面上方。再來，將投影面上方所有加工面投影至投影面；此投影面所形成的邊界區域與投影面正交。第三，我們將投影平面上的投影結果（一個或多個有界區域）切割成矩形區塊，並確認每塊矩形的製程需求（例如：每個矩形區塊可以產生刀具規格及刀徑方向）。本研究所提出製程需求表達法可明確找尋每個面可行加工刀具規格，而鄰面與鄰面間可依其特定刀具歸為一個加工特徵；因此，本研究可以擴展到在CAD邊界表示中辨識工件加工特徵。

This research proposes a method for modeling the specification of feasible cutters for producing a machined face on a workpiece represented in a CAD boundary representation. The proposed method is an extension of the work proposed by Wu & Liu (1991). Consider a workpiece under a given cutter approach direction. The determination of the process requirement model follows three steps. Firstly, for each machined face, we determine a projection plane with three constraints: (1) the plane is orthogonal to the cutter approach direction, (2) the face at least has an edge on the plane, and (3) the face is on the top side of the plane. Secondly, for each projection plane, we project each face on the top side of the projection plane onto the plane. After projection, a face orthogonal to the projection plane becomes an edge and a face on the projection plane remains a face. Thirdly, we divide the projection result on the projection plane into a set of rectangles, and determine the process requirement of each rectangle. The proposed process requirement modeling method explicitly presents the specifications of feasible cutters of each face; neighboring faces that can be produced by a particular cutter may form a machined feature. Therefore, this research may be extended to recognize machined features from a workpiece in CAD boundary representation.