پرینت سه بعدی قالب شن: یک بررسی و رویکرد جدید 3D sand mould printing: a review and a new approach

1. Introduction 1.1 3D sand mould printing 3D sand mould printing, as an application of AM in foundry industry and one kind of modern mold manufacturing technologies, is based on the combination of Computer Aided Design (CAD) and digital control technology to produce sand mould without wooden pattern. And sand mould usually has complex geometry and intricate cavity as well as high accuracy [1-3]. AM is a powerful tool for manufacture molds, also known as rapid prototyping (RP) [4]. AM is a process of joining materials to make objects from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing methodologies and the ASTM F42 Committee classifies AM processes into seven areas ,as listed below[4, 5]: Stereo lithography (SL), Fused Deposition Modeling (FDM), Ink Jet Printing (IJP), Three Dimensional Printing (3DP), Selective Laser Sintering (SLS), Laminated Object Manufacturing (LOM), Selective Laser Chemical Vapor Deposition. While in terms of basic molding movement, AM relays on addition between adjacent layers and movement of point to form line, then build surface in the layer. At present, the technology of rapid sand casting is widely used in so many fields including development, research and a lot of industries, having a far-reaching influence on the development of national economy. During a long cycle of research, development and use, the prototyping industry goes through enormous scientific and technological progress. Lots of science researchers have been attracted into this field. Singh and Rupinder classified technological development of prototyping as three phases, respectively, manual prototyping by a skilled craftsman, soft prototype by aid of computer software around mid-1970s and rapid prototyping (RP) applied to casting applications in early 1980s[3]. Usually, as shown in Fig. 1, there’re two main approaches, additive manufacturing (AM) and subtractive manufacturing (SM) for the manufacture of sand mould [6, 7]. And the typical rapid sand casting approaches include: Stereo lithography (SL), Selective laser sintering (SLS), Fused deposition modelling (FDM), Laminated object manufacturing (LOM), Drop-on-powder deposition inkjet printing technology (3DP) and Drop-on-drop deposition inkjet printing technology[3, 7-9], as well as Patternless casting manufacture technology (PCM)[1-3]. While for SM, Rapid manufacturing of sand molds by direct milling on sand block with Computer Numerical Control (CNC) is one representative [10, 11]. Patternless Casting CNC Manufacturing Technology [12-14] and digital precision forming technology without pattern casting from CAMTC [15, 16] both refer to this technique whereby moulds are directly machined out of blocks of sand. The companies applying this technology include CTI in England [17] and ACTech Company in Germany [18].