砂型铸造的中英文翻译

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Sand casting

　　A sand casting or a sand molded casting is a cast part produced by forming a mold from a sand mixture and pouring molten liquid metal into the cavity in the mold. The mold is then cooled until the metal has solidified. In the last stage the casting is separated from the mold. There are six steps in this process:

　　Place a pattern in sand to create a mold. Incorporate a gating system. Remove the pattern. Fill the mold cavity with molten metal. Allow the metal to cool. Break away the s[1]and mold and remove the casting.

　　There are two main types of sand used for molding. "Green sand" is a mixture of silica sand, clay, moisture and other additives. The "air set" method uses dry sand bonded to materials other than clay, using a fast curing adhesive. When these are used, they are collectively called "air set" sand castings to distinguish these from "green sand" castings. Two types of molding sand are natural bonded (bank sand) and synthetic (lake sand), which is generally preferred due to its more consistent composition.

　　With both methods, the sand mixture is packed around a master "pattern" forming a mold cavity. If necessary, a temporary plug is placed to form a channel for pouring the fluid to be cast. Air-set molds often form a two-part mold having a top and bottom, termed Cope and drag. The sand mixture is tamped down as it is added, and the final mold assembly is sometimes vibrated to compact the sand and fill any unwanted voids in the mold. Then the pattern is removed with the channel plug, leaving the mold cavity. The casting liquid (typically molten metal) is then poured into the mold cavity. After the metal has solidified and cooled, the casting is separated from the sand mold. There is typically no mold release agent, and the mold is generally destroyed in the removal process.[1]

　　The accuracy of the casting is limited by the type of sand and the molding process. Sand castings made from coarse green sand impart a rough texture on the surface of the casting, and this makes them easy to identify. Air-set molds can produce castings with much smoother surfaces. Surfaces can also be ground and polished, for example when making a large bell. After molding, the casting is covered in a residue of oxides, silicates and other compounds. This residue can be removed by various means, such as grinding, or shot blasting.

　　During casting, some of the components of the sand mixture are lost in the thermal casting process. Green sand can be reused after adjusting its composition to replenish the lost moisture and additives. The pattern itself can be reused indefinitely to produce new sand molds. The sand molding process has been used for many centuries to produce castings manually. Since 1950, partially-automated casting processes have been developed for production lines.　　

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砂型铸造

　　以型砂和芯砂为造型材料制成铸型，液态金属在重力下充填铸型来生产铸件的铸造方法。钢、铁和大多数有色合金铸件都可用砂型铸造方法获得。由于砂型铸造所用的造型材料价廉易得，铸型制造简便，对铸件的单件生产、成批生产和大量生产均能适应，长期以来，一直是铸造生产中的基本工艺。

　　砂型铸造所用铸型一般由外砂型和型芯组合而成。为了提高铸件的表面质量，常在砂型和型芯表面刷一层涂料。涂料的主要成分是耐火度高、高温化学稳定性好的粉状材料和粘结剂，另外还加有便于施涂的载体（水或其他溶剂）和各种附加物。

　　砂型
& }# q* m, X- V3 j制造砂型的基本原材料是铸造砂和型砂粘结剂。最常用的铸造砂是硅质砂。硅砂的高温性能不能满足使用要求时则使用锆英砂、铬铁矿砂、刚玉砂等特种砂。为使制成的砂型和型芯具有一定的强度，在搬运、合型及浇注液态金属时不致变形或损坏，一般要在铸造中加入型砂粘结剂，将松散的砂粒粘结起来成为型砂。应用最广的型砂粘结剂是粘土，也可采用各种干性油或半干性油、水溶性硅酸盐或磷酸盐和各种合成树脂作型砂粘结剂。砂型铸造中所用的外砂型按型砂所用的粘结剂及其建立强度的方式不同分为粘土湿砂型、粘土干砂型和化学硬化砂型3种。

　　粘土湿砂型
0 J1 T- G  }6 t以粘土和适量的水为型砂的主要粘结剂，制成砂型后直接在湿态下合型和浇注。湿型铸造历史悠久，应用较广。湿型砂的强度取决于粘土和水按一定比例混合而成的粘土浆。型砂一经混好即具有一定的强度，经舂实制成砂型后，即可满足合型和浇注的要求。因此型砂中的粘土量和水分是十分重要的工艺因素。