铸造工艺

Fundamental foundry process 铸造生产的主要工序

Molding造型

The product of the foundry is a casting. The first foundry process involved in the production of a casting is the construction of a suitable mold .The type of mold is governed the size and shape of the casting and the kind of metal to be used to make the casting. 铸造生产的产品是铸件。生产铸件的第一道工序是制作合适的铸型。铸型的类型是由铸件的尺寸、形状和制作铸件所用的金属种类决定的。

Green sand molds are made of sand in its green or natural state and may be poured with metal as soon as they are complete . About 85% of all mould made in the factory are of green sand. 湿型用温态（或自然状态）的砂制作成，在制作完毕后可立

即用金属浇注。铸造车间制作的全部铸型中约85%是湿型

Molding sand must be selected with great care , as much of the success or failure of casting depends on the sand mold. 必须精心地选择型砂，因为铸造的成败很在一部分

要取决于砂型

Dry sand molds are made of a special mixture of sand rammed in its damp state . When the mold has been complete , it is placed in an oven to bake. This process removes all mixture from the mold and leaves the body of the mold firm and dry

干型是用特殊的型砂混合料在温态下坚实而成，砂型制成后将其放入干燥炉中烘烤。这道工序除去铸型中所有水份，并使铸型型体坚实、干燥。

Core making 制芯

Cores are bodies of sand that form an opening or cavity in or through a casting . There are two types of cores , green sand and dry sand. The green sand core is a body of sand projecting into a mold to form a cavity or opening in the casting when the metal is poured. The green sand core is formed by the pattern during the molding process .

A dry sand core is composed of a special mixture of silica sand and a binding material. The core is rammed independently of mold and baked in an oven to remove all moisture. The bake core is placed in the finished mold before the mold is closed for pouring

制芯是在铸件中形成空腔或通孔的砂块，有两类砂芯，即湿砂芯和干砂芯。湿砂芯是向型腔内突出的砂块，当浇入金属时，在铸件内形成空腔或通孔。湿砂芯是造型过程中由模样形成。 干砂芯由硅砂和粘结剂的特殊混合组成。砂芯是与铸型分别坚实的，并在烘炉中以除去全部水分。烘烤过的砂芯在合箱前放入做好的铸型内。

Metal 熔炼

Metal used to form a casting must be in liquid form when it is poured into the mold. The kind of metal used will determine the type of furnace for the melting process. Metals with low melting point, such as lead , tin and zinc can be melted in an iron pot over an ordinary gas burner. Aluminum , brasses and bronzes require great heat and therefore are melted in gas-or oil-fired crucible furnaces. Cast iron requires the high temperature of the coke fired cupola furnace or the electric are furnace. The open hearth furnace , the converter or the electric furnace supply the high temperature necessary to metal steel.

用于构成铸件的金属，在浇铸型时必须液态。要根据所用的金属种类来确定熔炼工序所用的炉子类型

低熔点金属，如铅，锡和锌，可在铁罐中在普通的煤气炉上熔炬。铝，黄铜和青铜需要热量较多，因些要在煤气坩埚炉或燃油坩埚内熔炼铁。铸铁需燃焦碳的冲天炉或电弧炉的高温。平炉，转炉或电炉能提供熔炼铁钢所需的高温。

Pouring 浇注

The process of shaping molten metal in a mold is termed casting or pouring. The liquid metal is conveyed from the furnace to mold for this process. The containers in which the metal is carried are called ladles. The type and quantity of metal to be poured at one time will determine the kind and size of ladle used

液态金属在铸型中的成型工序称为铸造或浇注。为了进行这道工序，液态金属需从熔炉中运到铸型处。运载金属的容器叫浇包。根据金属种类和一次浇注的金属来确定所用的浇包类型和尺寸

Cleaning and finishing castings 铸件的清理和打磨

The solidified metal or castings is removed from the sand mold. The excess metal attached to the casting, in the form of gates, sprues, and rise and any sand that might be adhering to the casting is removed in the cleaning and finishing department. The cleaned castings are inspected and those requiring heat treatment are processed before they are shipped to the consumer .

凝固后的金属即铸件，从砂型中取出。与铸件连接的多余金属，如内浇口，直浇口，冒口以及粘附在铸件上的砂粒等都要在清理工序清除。清理过的铸件要经过检验，需需要专门热处理的铸件则发运经用户前进行热处理。

砂铸件铸造缺陷 sand-casting defects

Shot metal 冷豆

shot metal consits of little balls of the casting metal embedded in but not entirely fused with the castings. As the metal is poured into the mold it may spatter and spray , forming little balls which are thrown ahead of the flowing metal . This defect occurs when these little balls of metal do not fuse properly into the castings

是铸件金属小球，嵌在铸件内但未完全与铸件熔合。 当金属浇入铸型时，金属可能飞溅或喷射，形成小球，抛溅到金属流的前头。如果晕些小球未能很好地熔入铸件，就产生缺陷

Hot tears 热裂

hot tears or hot crack, are overtress failures which may occur in casting just after solidification when they are slight below the solidification temperature . in this temperature range , called the hot-short range, metals have low strengths.

是一种超应力断裂，它可能发生在刚凝固的铸件中， 铸件销低于凝固温度的时候，金属在这一称做热脆区的温度范围内强度较低。

Cold crack冷裂

a clean fresh fracture indicates a crack from external souress after cooling has been completed, this type of crack is called a cold crack.

清晰的新断口表明裂纹是在铸件完全冷却后由外部原因造成的，这样裂纹称为冷裂。 Warped 铸件变型

warped castings are deformed by internal stress which develop in a casting between

solidification and room temperatures .. Often it is design or shape of a castings that cause it to warp

是铸件在凝固温度和室温范围内由于内部应力的发展造 成翘曲变型。铸件翘曲变型常常是由于铸件设计或铸件的外型所引起的。

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