铸造翻译终稿(3)

sand should be sufficiently porous so that the gases are allowed to escape from the mould. This gas evolution capability of the moulding sand is termed as permeability.

渗透性：在铸件的凝固过程中，大量的气体将从铸型中排出，气体包括炉中金属吸收的、从大气和水蒸气中吸收的和其他由于浇注及型芯砂产生的。它们会在铸件中聚集并形成缺陷。型砂应该充分地多孔以使气体能够从铸型中逃逸。型砂的气体逸出能力被称为渗透性。

Beside those specific properties, the moulding sand should also have collapsibility so that during the construction of the solidified casting, it dose not provide any resistance which may result in cracks in the casting, they should be reusable and should have good thermal conductivity so that heat from the casting is quickly transferred.

除了这些明确的性能，型砂应该还有溃散性以确保在铸件凝固的过程中，不会有任何在铸件中可能导致裂纹的阻力。它们应该有重复使用性及好的热传导特性，以使铸件中的热量能够快速的转移出来。 5.3.3 Coremaking 5.3.3 制芯

Cores are forms, usually made of sand, which are placed into a mold cavity to form the interior surfaces of castings. Thus the void space between the core and mold-cavity surface is what eventually becomes the casting.

芯子使用砂子制作，放于型腔中以形成铸件内表面的一种实物形态，芯子和型腔表面的空间最终形成铸件。

Cores are the materials used for making cavities and hollow projections which cannot normally be produced by the pattern alone.

Any complicated contour or cavity can be made by means of cores so that really intricate shapes can be easily obtained. These are generally made of sand and are even used in permanent moulds. In general, cores are surrounded on all sides by the molten metal and are therefore subjected to much more severe thermal and mechanical conditions and as a result, the core sand should be of higher strength than the

moulding sand.

芯子是用于制作单个模样不能生产出的空腔和中空的突起部份的材料。

所有复杂的外型或型腔都能用芯子来实现，这才使得复杂形状容易得到。它们通常使用砂子制作，即使在金属型中也会使用。通常，芯子周围被金属液所填充，所以它要承受更加剧烈的传热学和力学条件。所以，芯砂应该比型砂有更高的强度

5.3.3.3 Core prints 5.3.3.3 芯撑

The core prints are provided so that the cores are securely and correctly positioned in the mould cavity. The design of core prints is such as to take care of the weight of the core before pouring and the upward metallostatic pressure of the molten metal after pouring. The core prints should also ensure that the core is not shifted during the entry of the metal is poured into the mould cavity.

芯撑是为了使芯子在型腔中完整正确的放置。设计芯撑是为了支撑浇注前芯子的重量和浇注后熔融金属的静压力，芯撑应当确保芯子在液态金属浇入到型腔时不会被冲走。

5.3.4 Elements of Gating systems 5.3.4 浇注系统的组成

As defined earlier, gating system refer to all those elements which are connected with the flow of molten metal from the ladle to mould cavity. The various elements that are connected with a gating system are (Fig. 5.26):

就像前面所定义的，浇注系统涉及到所有与液态金属流从浇包到型腔过程相关联的结构组成，这些与浇铸系统相关联的结构包括： ? Pouring basin ? Sprue

? Sprue base well

? Runner

? Runner extension ? Riser ? Chill

Fig. 5.26 Typical gating system

浇口杯； 直浇道； 直浇道窝； 横浇道； 横浇道延伸； 冒口； 冷铁；

In this section the functions and the design of the various elements of a gating system will be discussed. Any gating system designed should aim at providing a defect free casting. This can be achieved by making provision for certain requirements while designing the gating system. These are as follows:

在这一部分，将会讨论许多浇注系统元素的设计和作用。所有浇注系统设计的目标是为了得到无缺陷铸件，在设计浇注系统时，可以通过针对特定的要求做出安排来实现。

1. the mould should be completely filled in the smallest time possible without

having to raise metal temperature nor use higher metal heads. 2. the metal should flow smoothly into the mould without any turbulence. A

turbulent metal flow tends to form dross in the mould 3. unwanted material such as slag, dross and other mould material should not be allowed enter the mould cavity

4. the metal entry into the mould cavity should be properly controlled in such a

way that aspiration of the atmospheric air is prevented 5. a proper thermal gradient should be maintained so that the casting is cooled without any shrinkage cavities or distortions 6. metal flow should be maintained in such a way that no gating or mould

erosion take place. 7. the gating system should ensure that enough molten metal reaches the mould

cavity

8. the gating system design should be economical and easy to implement and

remove after casting solidification

9. ultimately, the casting yield should be maximized

1.铸型应该在尽可能短的时间里完全充满，而不必要通过提高金属温度或使用高的金属静压头。

2.金属应该没有任何紊流的平稳流入铸型中，紊动的金属流容易在铸型中形成渣滓。

3.不期望的材料，比如熔渣、渣滓和其他模型材料不应允许进入型腔内。 4.对进入型腔中的金属液应该用一种阻止大气气体吸入的方法进行适当的控制。

5.应该保持一个适当的温度梯度以使铸件在冷却中不会出现任何的缩孔或变形。

6.金属应当保持一种不会出现浇注腐蚀或铸型腐蚀的流动方式。 7.浇铸系统应当确保足够的熔融金属到达型腔中。

8.浇注系统的设计应当经济和易于实施及在铸件凝固后移走。 9.最终，铸件应该实现大批量生产。

To have all these requirements together is a tall order, still a mould designer should strive to achieve as many of the above objectives as possible. Before going into the mechanics of gating design, let us describe some of the functions and types of various gating system elements

满足以上的需要是一个很高的要求，一个铸型设计人员应当努力去达到以上尽可能多的

目标。在进行浇注系统结构设计之前，让我们先讲述一下多种浇注系统组成的作用及分类。 5.3.3.1

Pouring basin

5.3.4.1 浇口杯

The molten metal is not directly poured into the mould cavity because it may cause mould erosion. Molten metal is poured into a pouring basin which acts as a reservoir from which it moves smoothly in to sprue. The pouring basin is also able to stop the slag from entering the mould cavity by means of a skimmer or skim core as shown in Fig.5.27. It hold back the slag sand dirt which floats on the top and only allow the clean metal underneath it into the sprue. The pouring basin may be cut into the cope portion directly or a separate dry sand pouring basin may be prepared and used as shown in Fig.5.27. the molten metal in the pouring basin should be full during the pouring operation, otherwise a funnel is likely to form through which atmospheric air and slag may enter the mould cavity.

(a) Green sand (b) Dry sand Fig. 5.27 Pouring basin

由于可能造成铸型的腐蚀，熔融的金属液并没有直接浇入到型腔中。熔融金属倒入一个有贮存作用的浇口杯并平稳的进入到直浇道中，浇口杯还有通过图5.27所示的撇渣器或撇渣芯阻挡渣子进入型腔的能力。它保留了漂浮在上层的砂污渣子，只允许其下方的洁净金属进入直浇道。浇口杯可以直接从端盖部分分开，

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