【正文】 鋼橫梁容易斷裂。鉚接工藝比較復雜。參考文獻[1]黃天佑，黃乃瑜，[M].北京:機械工業(yè)出版社，2007[2] 王峰，[M].北京:機械工業(yè)出版社，1998[3][M].北京:清華大學出版社，2007[4] 郭年琴，[J].世界有色金屬，2009[5] [J].礦山機械，2004[6] 董秀琦，[M].北京:機械工業(yè)出版社，2005[7] 吳卓，[M].北京:北京理工大學，2009[8] 聞邦春，劉鳳翔，、振動給料機、振動輸送機的設計與調試[M].北京:北京化工出版社，1989,2[9] 吳麗娟，[J].機械工程師[10] [M].北京:[11] 趙永剛，[M].北京:科學出版社，2010[12] [M].北京: 外文原文語翻譯Fluidity dan Roughness during LostFoam Casting of Abstract Lostfoam casting is a casting technique that uses expanded polystyrene (EPS) foam as a mold pattern embedded into silica sand. The EPS foam is evaporated due to contact with melts. The aim of this works is to investigate the effect of pouring temperature, polystyrene foam density and sand mesh size on fluidity and roughness during lostfoam casting of . The mold patterns of EPS foam with densities of 720 kg/m3 and the thickness of 311 mm were pacted in a box with various silica sand mesh size 2070. The aluminum alloy was melted in a crucible furnace and poured at temperatures of 680740 ℃. The experimental results show that the fluidity increases directly with the increasing of pouring temperature, the decreasing of EPS foam density and of EPS foam thickness. The roughness decreases with the increasing sand mesh size.Keywords: fluidity, roughness, lostfoam casting1. IntrodusctionLost foam casting is a casting method that uses the pattern of expandable polystyrene (EPS) foam. EPS foam will be soft at a temperature of about 95 ℃ and be a viscous liquid at 120180℃ and be diluted above 250 ℃, and then be deposed above 330 ℃. Polystyrene consists of EPS and PMMA. Both polymers have the atom C and H [1]. One of the advantages of lostfoam casting is flexibility in the design of the casting pattern. A plex shapes that are difficult to make by other methods can be made with this method. The casting method is not only speed up in making a prototype of a cast product, but also has bee a method for mass production. The process is environmentally friendly, because there are no waste products during the process. Molding sands can be used again for further casting process. Another advantage of this method is reducing additional machining process, because of the dimension of the patterns created properly and do not need the additional tolerance for machining A lower production costs is also the important feature of this casting method, because the pattern is made of EPS foam and equipment for casting is simple and inexpensive, so it can be used for small scale foundry. Researches on the lostfoam casting have been carried out by some researcher. The research on lost foam casting are mainly on aluminum alloys, such A356 [1, 2, 3, 4], [5], A319 [6]. The research of lostfoam casting on other materials is also reported, AZ91 [7], AM60B [8] and gray cast iron [9]. The fluidity of melts during lostfoam casting increases with melt temperature [1, 8]. The fluidity also increases with sand temperature [7]. Coating of pattern with ceramic improves the fluidity [7]. The thickness of mold patterns influences the fluidity [1].The foam density is also influences fluidity [8] in which the ability of the molten metal fills the mold patterns with a density of lb/ft3 better than polystyrene foam with a density of and lb/ft3. Patterns with low density polystyrene foam show a sound casting. The ability of the molten metal fills the mold pattern with a density of 26 kg/m3 is faster than that of the pattern density 21 kg/m3. Filling speed of molten metal reaches to cm/sec for the mold pattern with a density of 26 kg/m3, and reached to cm/sec in the mold pattern with a density of 21 kg/m3 [7]. The liquid metal filling rate increases with permeability of sand mold [6]. Liquid metal reached a length of 150 mm for secs for the mold sand with AFS type 20 and seconds the mold sand with AFS 55 [7]. A fluidity is obtained by coating the mold pattern 45 Bc (high density) than the pattern of the mold with coating 35 Bc (low density). The porosity in casting products increases with density of polystiren foam [5] and melts temperature [4,7]. Surface roughness is also an important issue which must be optimized in materials processing. The rough surfaces are often hindered in many structural applications. The rough surface reduces corrosion resistance and fatigue strength. The aim of this research is to investigate the effect of pouring temperature, EPS foam density and sand mesh size on fluidity and surface roughness during lostfoam casting of .2. ExperimentThe material used was aluminum alloy , with chemical positions (wt%) Si, Fe, Mg, Zn, Ti and bal Al. The pattern was prepared by a hot wire cutter from an EPS (expanded polystyrene) foam block. In order to study the effects of pouring temperature, EPS foam density, sand mesh size and pattern thickness, experiments were conducted with various pouring temperatures, EPS foam density, sand mesh size and pattern thickness. The density of pattern of the EPS was 7, 18 and 20 kg/m3. Silica sand was used with mesh 70 ( 70 mesh), mesh 35 (35 mesh up to 70 mesh) and 20 mesh (20 mesh to 35 mesh). Aluminum alloy was melted in the crucible furnace at temperature 750 ℃, and then poured at 680, 710 and 740℃. Figure 1. Patern of EPS (expandable polystyrene) foam.An engineering drawing of the test pattern used to study the fluidity characteristics is shown in Fig. 1. A strip, 180 mm long, 15 mm width and 3, 5, 7 and 11 mm thick was attached to a gating system consisting of a rectangular downsprue and apouring 25 mm in cross section. The gating system and the strip were cut from EPS foam boards. The patterns were not coated with a mercial coating. Pattern was put on the base of the flask, and the flask was filled with mold packing sand in vibration. Molten aluminum was poured into EPS foam pattern. The fluidity was determined by measuring the length of cast products at every thickness of sample.