Chapter 2 Casting Processes of Metals
第二章：金属的铸造工艺
A casting may be defined as a \to solidify in a mold \the shape of the object being determined by the shape of the mold cavity. Casting is basically melting a solid material, heating to a special temperature, and pouring the molten material into a cavity or mold, which is in proper shape. Casting has been known by human being since the 4th century B.C.
铸造可以被定义为：“通过使熔融的金属液在铸型中凝固而得到金属物体”，物体的形状由型腔的形状决定。基本上来说，铸造就是将固态材料熔化、加热到一个特定的温度，然后将熔融的材料浇注到有确定形状的型腔或铸型中。早在公元前4世纪，铸造就被人类所了解。 2. 1 Casting Procedure 2．1铸造过程
In all casting processes six basic factors are involved. These are as follows: 所有的铸造工艺都包括六个基本因素。介绍如下：
1. A mold cavity, having the desired shape and size and with due allowance for shrinkage of the
solidifying metal, must be produced. Any complexity of shape desired in the finished casting must exist in the cavity. Consequently, the mold material must such as to reproduce the desired detail and also have a refractory character so that it will not be significantly affected by the molten metal that it contains. Either a new mold must be prepared for each casting, or it must be made from a material that can withstand being used for repeated castings, the latter being called permanent molds.
1．必须制作出一个具有所要求形状、大小和由于金属凝固过程收缩而造成的应有公差的型腔。在精密铸造中，所有需求形状的复杂部分都要存在于型腔中，通常，铸型材料必须是为了复制出所需要的零件，同时要有一定的耐火特性以确保它不会被所包容的熔融金属严重影响，每一次铸造都要准备一个新的铸型，或者必须使用一种能够经受重复铸造的模型材料，后者被称为金属模。
2. A suitable means must be available for melting the metal that is to be cast, providing not only adequate temperature, but also satisfactory quality and quantity at low cost.
2．与之相匹配的熔化铸造金属方法必须是有效的，其不仅要提供精确的温度，而且要在低成本的基础上提供令人满意的质量和数量。
3. The molten metal must be introduced into the mold in such a manner that all air or gases in
the mold, prior to pouring or generated by the action of the hot metal upon the mold, will escape, and the mold will be completely filled. A quality casting must be dense and free from defects such as air holes.
3．熔融的金属被引入型腔中时，必须采用这样一种方法：使在浇注或在热的金属液与型腔
发生作用之前，铸型中所有空气和气体将会逸出，并使型腔能够充满。 4. Provision must be made so that the mold will not cause too much restraint to the shrinkage
that accompanies cooling after the metal has solidified. Otherwise, the casting will crack while its strength is low. In addition, the design of the casting must be such that solidification and solidification shrinkage can occur without producing cracks and internal porosity or voids. 4．必须提供补缩以确保型腔不会产生太大由于金属凝固后随冷却收缩引起的应力。否则，
当强度太低时，铸件就会开裂且强度很低。另外，铸件设计必须确保在凝固和凝固收缩过程中不会产生裂纹、缩松和缩孔。
5．It must be possible to remove the casting from the mold so a permanent mold must be made in two or more sections.
5．必须使铸件能够从型中取出，这就要求金属模必须分为两个或两个以上的部分。
6．After removal from the mold, finishing operations may need to be performed to remove
extraneous material that is attached to the casting as the result of the method of introducing the metal into the cavity, or is picked up from the mold through contact with the metal.
6．将铸件从型腔中移出后，可能需要一些清理操作，以除去由于金属引入型腔或金属与模型接触而附属于铸件的多余部分。
2. 2 Casting Terms 2．2 铸造术语
In the following sections, the details of sand casting process which represents the basic process of casting would be seen. Because going into the details of the process, defining a number of casting vocabulary words would be appropriate. Reference may please be made to Fig. 2.1
在下面的部分，将会介绍代表着最基本铸造工艺的砂型铸造工艺细节，由于要进行工艺细节的探讨，定义一些铸造用词汇是十分必要的，参考如图2.1 Flask: A moulding flask is one which holds the sand mould intact. Depending upon the position of the flask in the mould structure it is referred to by various names such as drag-lower moulding flask, cope-upper moulding flask and cheek-intermediate moulding flask used in three-piece moulding. It is made up of wood for temporary applications and more generally of metal for long-term use.
砂箱：一个造型用砂箱就是保持砂型完整无缺，依据砂箱在铸型结构中位置，其被冠以多个名字，比如在三箱造型中使用的下型砂箱、上型砂箱和中型砂箱。短期使用由木头构成；长期使用通常用金属制作。
Pattern: Pattern is a replica of the final object to be made with some modifications. The mould cavity is made with the help of the pattern.
模样：模样是经过一些修改的最终产品的复制品，型腔是在模样的帮助下制作出来的。
Parting Line: This is the dividing line between the two moulding flasks that makes up the sand mould. In split pattern it is also the dividing line between the two halves of the pattern.
分型线：它是组成砂型两砂箱之间的分离线，在劈模中，它也是模样两半型之间
的分型线。
Bottom board: This is a board normally made of wood which is used at the start of the mould making. The pattern is first kept on the bottom board, sand is sprinkled on it and then ramming is done in the drag. 底板: 它通常是一个用木头制作、用于造型开始时的平板，首先把模样放在底板上，然后将砂洒在模样上，然后在下箱中捣实。
Facing sand: The small amount of carbonaceous material sprinkled on the inner surface of the moulding cavity to give a better surface finish to the castings. 面砂：少量洒在型腔内表面以得到更好的铸件表面光洁度的含碳材料。
Fig. 2.1 Cross section of a sand mould
Moulding sand: It is the freshly prepared refractory material used for making the mould cavity. It is a mixture of silica, clay and moisture in appropriate proportions to get the desired results and it surrounds the pattern while making the mould.
型砂：用于制作型腔的新备难熔材料，它是硅石、粘土和水分为得到所需结果的适当比例的混合物。在造型过程中包围在模样的四周。
Backing sand: It is what constitutes most of the refractory material found in the mould. This is made up of used and burnt sand.
背砂：它组成了铸型中所能找到的耐火材料的绝大部分，由使用过和烧过的砂组成。
Core: It is used for making hollow cavities in castings. 芯：用于制作在铸件中的空腔。
Pouring basin: A small funnel shaped cavity at the top of the mould into which the molten metal is poured.
浇口杯：一个在铸型上端熔融金属注入的小漏斗型空腔。
Sprue: The passage through which the molten metal from the pouring basin reaches the mould cavity. In many cases it controls the flow of metal into the mould. 直浇道：熔融金属从浇口杯到达型腔的一个通道，在很多的情况下，它控制着进入型腔中的金属流。
Runner: The passageways in the parting plane through which molten metal flow is regulated before they reach the mould cavity.
横浇道：使液态金属流在到达型腔前得到调整的分型面上的通道。 Gate: The actual entry point through which molten metal enters mould cavity. 内浇口：液态金属进入型腔的实际入口点。
Chaplet: Chaplets are used to support cores inside the mould cavity to take care of its own weight and overcome the metallostatic force. 芯撑：芯撑用于支撑在型腔中的芯子，以支撑芯子本身重量和消除金属静力学应力。
chill: Chill are metallic object which are placed in the mould to increase the cooling rate of casting to provide uniform or desired cooling rate.
冷铁：冷铁是放于铸型中增加铸件冷却速度，以提供同一冷速或所需冷却速度的金属物体。
Riser: It is reservoir of molten metal provided in the casting so that hot metal can flow back into the mould cavity when there is a reduction in volume of metal due to solidification.
冒口：它是在铸造中提供液态金属的储备，目的是使热的金属在凝固过程中出现体收缩情况下能回流到型腔中。