【正文】 116:357–63. [10] Hilbert D, CohnVossen S. Geometry and the imagination, New York: Chelsea, 1983 Translated by P. Nementi. 。1:317–26. [8] Hui KC. Geometric aspects of the mouldability of parts. Computer Aided Design 1997。26:68–73. [6] Ganter MA, Skoglund PA. Feature extraction for casting core development. ASME, Journal of Mechanical Design 1993。25:762–8. [4] Chen LL, Chou SY, Woo TC. Partial visibility for selecting a parting direction in mould and die design. Journal of Manufacturing Systems 1995。46/1:429–32. [2] Nee AYC, Fu MW, Fuh JYH, Lee KS, Zhang YF. Automatic determination of 3D parting lines and surfaces in plastic injection mould design. Annals of the CIRP 1998。 and 2. Same undercut volume, but the undercut directions can be different. If a pound undercut feature covers other small undercut features, they should meet the following conditions: (1) Geometrical entities condition: and (2) Undercut volume condition: If an undercut feature k meets the above conditions, it will cover undercut features i and j. In Fig. 18, as undercut feature 1 meets the above conditions, it includes undercut features 2 and 3. Undercut features 2 and 3 must therefore be removed from the undercut feature . 13 (一 ) (b) (c) (d) 圖 18 8. Blending surfaces in moulding In the moulding, the blending surfaces are often used in smoothing the junction of two surfaces. This is done for the reasons of good stress distribution, good mouldability and for certain special functions of the moulded parts. Actual and virtual edges The actual edges of the target surface form the external edgeloop of the target surface。 Injection mould design 1. Introduction Mould and die making is an important supporting industry since their related products represent more than 70% of the nonstandard ponents in consumer products. The production runs, however, are typically of small lotsize and with great varieties. The high demand for shorter design and manufacturing lead times, good dimensional and overall quality, and rapid design changes has bee the bottlenecks in die and mould industries. For mouldmaking panies wishing to maintain the petitive edge, there is the urgent need to shorten the design and manufacturing lead times by automating the design process using advanced manufacturing equipment, processes and improving the skill level of their employees. Currently, some of the mouldmaking panies use 3D mercial CAD software tools to design moulds, however, many panies are still designing moulds 9 manually, which is timeconsuming and errorprone. The development of a ComputerAided Injection Mould Design System (CAIMDS) has bee the focus of research in both industry and academia. 2. Definition and classification of undercut features In a moulding, concave regions such as local recesses, slots, pockets and holes are potential undercut features。 8 附件 2：外文原文 （復(fù)印件） Undercut feature recognition in an injection mould design system In the design of plastic injection moulds, the presence of undercut features would affect mould cost and structure. In this paper, the definition, classification of undercut features and the related notions to identify them are presented. Based on the proposed undercut feature definition and taxonomy, the relationships between the undercut featur