一、 外文原文A Parametric-Controlled Cavity Layout Design System for a Plastic Injection MouldM. L. H. Low and K. S. LeeDepartment of Mechanical Engineering, National University of Singapore, SingaporeToday, the time-to-market for plastic products is becoming shorter, thus the lead time available for making the injection mould is decreasing. There is potential for timesaving in the mould design stage because a design process that is repeatable for every mould design can be standardised. This paper presents a methodology for designing the cavity layout for plastic injection moulds by controlling the geometrical parameters using a standardisation template. The standardization template for the cavity layout design consists of the configurations for the possible layouts. Each configuration of the layout design has its own layout design table of all the geometrical parameters. This standardisation template is pre-defined at the layout design level of the mould assembly design. This ensures that the required configuration can be loaded into the mould assembly design very quickly, without the need to redesign the layout. This makes it useful in technical discussions between the product designers and mould designers prior to the manufacture of the mould. Changes can be made to the 3D cavity layout design immediately during the discussions, thus saving time and avoiding miscommunication. This standardisation template for the cavity layout design can be customised easily for each mould making company to their own standards.Keywords: Cavity layout design; Geometrical parameters;Mould assembly; Plastic injection mould design; Standardisationtemplate1. IntroductionPlastic injection moulding is a common method for the mass production of plastic parts with good tolerances. There are two main items that are required for plastic injection moulding. They are the injection-moulding machine and the injection mould. The injection-moulding machine has the mould mountedon it and provides the mechanism for molten plastic transfer from the machine to the mould, clamping the mould by the application of pressure and the ejection of the formed plastic part. The injection mould is a tool for transforming the molten plastic into the final shape and dimensional details of the plastic part. Today, as the time-to-market for plastic parts is becoming shorter, it is essential to produce the injection mould in a shorter time.Much work had been done on applying computer technologies to injection mould design and the related field. Knowledge-based systems (KBS) such as IMOLD 1,2, IKMOULD3, ESMOLD 4, the KBS of the National Cheng Kang University, Taiwan 5, the KBS of Drexel University 6, etc. were developed for injection mould design. Systems such as HyperQ/Plastic 7, CIMP 8, FIT 9, etc. are developed for the selection of plastic materials using a knowledge-based approach. Techniques have also been developed for parting design in injection moulding 1012.It has been observed that although mould-making industries are using 3D CAD software for mould design, much time is wasted in going through the same design processes for every project. There is great potential for timesaving at the mould design stage if the repeatable design processes can be standardized to avoid routine tasks. A well-organised hierarchical design tree in the mould assembly is also an important factor 13,14.However, little work has been done in controlling the parameters in the cavity layout design; thus this area will be our main focus. Although there are many ways of designing the cavity layout 15,16, mould designers tend to use only conventional designs, thus there is a need to apply standardisation at the cavity layout design level.This paper presents a methodology for designing the cavity layout for plastic injection moulds by controlling the parameters based on a standardisation template. First, a well-organised mould assembly hierarchy design tree had to be established. Then, the classification of the cavity layout configuration had to be made to differentiate between those with standard configurations and those with non-standard configurations. The standard configurations will be listed in a configuration database and each configuration has its own layout design table that controls its own geometrical parameters. This standardization template is pre-defined at the layout design level of the mould assembly design.2. Cavity Layout Design for a Plastic Injection MouldAn injection mould is a tool for transforming molten plastic into the final shape and dimensional details of a plastic part. Thus, a mould contains an inverse impression of the final part. Most of the moulds are built up of two halves: the front insert and the back insert. In certain mould-making industries, the front insert is also known as the cavity and the back insert is known as the core. Figure 1 shows a front insert (cavity) and a back insert (core). Molten p