unit3 铸造工艺

Casting processes and cast-material technologies vary from simple to highly complex. Material and process selection depends on the part’s complexity and function, the product’s quality specifications, and the projected cost level. 铸造工艺和铸造材料技术从简单到高度复杂 变化很大。材料和工艺的选择取决于零件的复杂 性和功能、产品的质量要求以及成本预算水平。
将浇注系统的垂直部分与浇注杯连接的是浇注口浇注系统的水平部分称为浇道最后到多点把熔化金属导入型腔的称为闸道
Professional English
北华大学机械学院 王开宝
Unit 3
Casting is a manufacturing process in which molten metal is poured or injected and allowed to solidify in a suitably shaped mold cavity. During or after cooling, the cast part is removed from the mold and then processed for delivery. 铸造是一种将熔化的金属倒入或注入合适的 铸模腔并且在其中固化的制造工艺。在冷却期间 或冷却后，把铸件从铸模中取出，然后进行交付。
The vertical part of the gating system connected to the pouring cup is the sprue, and the horizontal portion is called the runners and finally to the multiple points where it is introduced to the mold cavity called the gates. 将浇注系统的垂直部分与浇ቤተ መጻሕፍቲ ባይዱ杯连接的是浇 注口，浇注系统的水平部分称为浇道，最后到多 点把熔化金属导入型腔的称为闸道。
Sand Casting
砂型铸造
Sand casting is used to make large parts (typically iron, but also bronze, brass, aluminum). Molten metal is poured into a mold cavity formed out of sand (natural or synthetic). 砂型铸造用于制造大型零件(具有代表性是 铁，除此之外还有青铜、黄铜和铝)。将熔化的 金属倒入由型砂(天然的或人造的)做成铸模腔。
The drag is first filled partially with sand, and the core print, the cores, and the gating system are placed near the parting line. The cope is then assembled to the drag, and the sand is poured on the cope half, covering the pattern, core and the gating system. 首先往下型箱里部分地填入型砂和砂芯座、 砂芯，并在靠近分型线处放置浇注系统。然后将 上型箱与下型箱装配在一起，再把型砂倒入上型 箱盖住型模、砂芯和浇注系统。
The cavity is usually made oversize to allow for the metal contraction as it cools down to room temperature. This is achieved by making the pattern oversize. To account for shrinking, the pattern must be made oversize by these factors on the average. These are linear factors and apply in each direction. 型腔通常大于所需尺寸以允许在金属冷却到室 温时收缩。这通过把型模做得大于所需尺寸来达到。 为解决收缩效应，一般而言型模做得比所需尺寸大， 必须考虑线性因素并作用于各个方向。
This is facilitated by designing a draft, a slight angular offset from the vertical to the vertical surfaces of the pattern. This is usually a minimum of 1.5mm(0.060in.), whichever is greater. The rougher the surface of the pattern, the more the draft to be provided. 通过设计拔模斜度—型模垂直相交表面的微小 角度偏移量—来使取出型模变得容易。拔模斜度最 小一般为1.5mm(0.060in.)，只能比此大。型模表 面越粗糙，则拔模斜度应越大。
In a two-part mold, which is typical of sand castings, the upper half, including the top half of the pattern, flask, and core is called cope and the lower half is called drag, as shown in Fig.3.1. The parting line or the parting surface is line or surface that separates the cope and drag. 在典型砂型铸造的两箱铸模中，上半部分(包 括型模顶半部、砂箱和砂芯)称为上型箱，下半部 分称为下型箱，见图3.1所示。分型线或分型面是 分离上下型箱的线或面。
Additionally there are extensions to the gating system called vents that provide the path for the built-up gases and the displaced air to vent to the atmosphere. 除此之外，还有称为排放口的浇注系统延长 段，它为合成气体和置换空气排放到大气提供通 道。
Castings are parts that are made close to their final dimensions by a casting process. With a history dating back 6,000 years, the various casting processes are in a state of continuous refinement and evolution as technological advances are being made. 通过铸造加工，铸件可以做成很接近它们的最 终尺寸。回溯6,000年历史，各种各样的铸造工艺 就如同科技进步一样处于一个不断改进和发展的状 态。
The cavity in the sand is formed by using a pattern (an approximate duplicate of the real part), which are typically made out of wood, sometimes metal. The cavity is contained in an aggregate housed in a box called the flask. 砂型里的型腔是采用型模(真实零件的近似复 制品)构成的，型模一般为木制，有时也用金属制 造。型腔整个包含在一个被放入称为砂箱的箱子 里的组合体内。
The molten material is poured into the pouring cup, which is part of the gating system that supplies the molten material to the mold cavity. 熔化的金属从浇注杯注入型腔，浇注杯是浇 注系统向型腔提供熔化金属的部分。
The sand is compacted by vibration and mechanical means. Next, the cope is removed from the drag, and the pattern is carefully removed. The object is to remove the pattern without breaking the mold cavity. 型砂通过振动和机械方法压实。然后从下型 箱上撤掉上型箱，小心翼翼地取出型模。其目的 是取出型模而不破坏型腔。
A riser is an extra void created in the mold to contain excessive molten material. The purpose of this is to feed the molten metal to the mold cavity as the molten metal solidifies and shrinks, and thereby prevents voids in the main casting. 冒口是在铸模内部增加的额外空间，用于容 纳过多的熔化金属。其目的是当熔化金属凝固和 收缩时往型腔里补充熔化金属，从而防止在主铸 件中产生孔隙。
The processes of sand casting are discussed in this section, including patterns, sprues and runners, design considerations, and casting allowance. 本节讨论砂型铸造工艺，包括型模、浇注口、 浇道、设计考虑因素及铸造余量。
Core is a sand shape inserted into the mold to produce the internal features of the part such as holes or internal passages. Cores are placed in the cavity to form holes of the desired shapes. Core print is the region added to the pattern, core, or mold that is used to locate and support the core within the mold. 砂芯是插入铸模的砂型，用于生成诸如孔或内 通道之类的内部特征。砂芯安放在型腔里形成所需 形状的孔洞。砂芯座是加在型模、砂芯或铸模上的 特定区域，用来在铸模内部定位和支撑砂芯。
These shrinkage allowances are only approximate, because the exact allowance is determined by the shape and size of the casting. In addition, different parts of the casting might require different shrinkage allowances. 收缩余量仅仅是近似的，因为准确的余量是 由铸件的形状和尺寸决定的。另外，铸件的不同 部分也可能需要不同的收缩余量。