铸造翻译终稿(4)

或者可以准备一个如图5.27所示单独的干砂浇口杯使用。在浇注操作中，熔融的金属液应该充满浇口杯，否则易于形成一个漏斗，大气气体和渣滓会通过它进入到型腔中去。

One of the walls of the pouring basin is made inclined at about 45°to the horizontal. The molten metal is poured on this face such that metal momentum is absorbed and vortex formation is avoided. In some special cases the pouring basin may consist of partitions to allow for the trapping of the slag and maintaining constant metal height in the basin.

浇口杯的其中一个壁做成了与水平呈45度的倾斜。液态金属倾倒在这个平面上以消除

金属动量和避免形成涡流。在一些特别的情况下，浇口杯可构成允许截渣和保持杯中恒定的金属高度的部分。 5.3.3.2

Sprue

5.3.4.2 直浇道

Sprue is the channel through which the molten metal is brought into the parting plane where it enters the runners and gate to ultimately reach the mould cavity. The molten metal when moving from the top of the cope to the parting plane grains in velocity and as a consequence requires a smaller area of cross section for the same amount of metal to flow at the top. If the sprue were to be straight cylindrical as shown in Fig. 5.28(a), then the metal flow not be full at the bottom, but some low pressure area would be created around the metal in the sprue. Since the sand mould is permeable, atmospheric air would be breathed into this low pressure area which would then be carried to the mould cavity. To eliminate this problem of air aspiration the sprue is tapered to gradually reduce the cross section as it moves away from the top of the cope as shown in Fig.5.28(b).

(a)Straight sprue (b) Tapered

Fig. 5.28 Sprue

直浇道是液态金属被引入分型面的一个通道，通过分型面，液态金属进入横浇道和浇口并最终进入到型腔中。液态金属从顶端到分型面获得了一个速度，结果，当等量的金属在顶端流动时，要求一个更小的横截面即可。如果直浇道做成如图5.28（a）所示的直圆柱形，金属流在底部将不会充满，而会在直浇道中围绕金属液形成低压区。由于砂型具有渗透性，大气气体将会被吸入这个低压区，并随后进入到型腔中。为消除气体吸入的问题，直浇道做成锥形的以逐渐减少如图5.28（b）中金属从顶端往下流动的横截面积。

5.3.3.3 Sprue base well 5.3.4.3 直浇道窝

This is a reservoir for metal at the bottom of the sprue to reduce the momentum of the molten metal. The molten metal as it moves down the sprue grains in velocity, some of which is lost in the sprue base well by which the mould erosion is reduced. This molten metal changes direction and flows into the runners in a more uniform way.

这是一个为了减少熔融金属动量而设计的在直浇道底部的金属液储存器，在金属从直浇道中下降时获得速度，其中的一些在直浇道窝中失去了，从而减少了铸型的腐蚀。熔融的液态金属改变了方向并以一种更均匀的方式流进了横浇道。

5.3.4.4 Runner 5.3.4.4 横浇道

It is generally located in the horizontal plane (parting plane) which connects the sprue to its ingates, thus letting the metal enter the mould cavity. The runners are normally made trapezoidal in cross section. It is a general practice for ferrous metals to cut the runners in the cope and the ingates in the drag. The main reason for this is to trap the slag and dross which are lighter and thus trapped in the upper portion of the runners. For effective trapping of the slag, runners should flow full. When the amount of molten metal coming from the down sprue is more than the amount flowing through the ingates, the runner would always be full and thus slag trapping would take place. But when the metal flowing through the ingates is more than that flowing through the runners, then the runner would be filled only partially and the slag would then enter the mould cavity.

它通常位于连接直浇道到内浇口的水平分型面上，从而使金属进入到型腔中。直浇道横截面形状通常做成梯形。对于黑色金属，通常实际生产中在上箱开辟横浇道、在下箱开辟内浇口。主要的原因是为了阻挡较轻的位于直浇道上部的渣滓，为了有效的挡渣，横浇道应该充满，当从直浇道进入的熔融金属液量多于流经内浇口的量时，横浇道就会被充满从而实现了挡渣。但是当流经内浇口的金属多于流经横浇道的时，横浇道只有部分被填充，渣滓将会进入到型腔中去。

5.3.4.5 Runner extension 5.3.4.5 横浇口延伸端

The runner is extended a little further after it encounters the ingate. This extension is provided to trap the slag in the molten metal. The metal initially comes along with the slag floating at the top of the ladle and this flows straight, going beyond the ingate and trapped in the runner extension.

当横浇道和内浇口相交时它会有一点延伸，这个延伸是为了阻挡熔融金属液中的渣滓。最初金属和漂浮在浇包上方的渣滓向前直流，流过内浇口并在横浇口延伸端被阻挡渣滓。

5.3.4.6 Riser

5.3.4.6 冒口

Most of the foundry alloys shrink during solidification. Table 10.1 shows the various volumetric shrinkages for typical material. As a result of this volumetric shrinkage during solidification, voids are likely to form in the castings unless additional molten metal is fed into these places which are termed as hot spots since they remain hot till the end. Hence a reservoir of molten metal is to be maintained from which the metal can flow readily into the casting when the need arises. These reservoirs are called risers.

多数的铸造合金在凝固过程中收缩。表格10.1说明了典型材料的各种体积收缩量。由于这种在凝固过程中的体积收缩量，铸件就趋于形成缩孔，除非额外的液态金属进入到由于直到最后都是保持热而被术称为热节的区域内。因此一个熔融金属的储存器必须准备，通过它金属在需要时能够平稳的流入到铸件中。

As shown in Table 5.6, different materials have different shrinkages and hence the riser requirements vary for the materials. In grey cast iron, because of graphitization during solidification, there may be an increase in volume sometimes. This if course, depends on the degree of graphitization in grey cast iron which is controlled by the silicon content.

如表5.6的说明，不同的材料有不同的收缩，因此冒口的要求因材料不同而不同。在灰铸铁中，由于凝固过程中的石墨化，有时会出现体积膨胀。这种情况的出现，取决于灰铸铁中由含硅量所控制的石墨化程度。

In order to make them effective, the riser should be designed keeping the following in mind.

1. the metal in the riser should solidify in the end.

2. the riser volume should be sufficient for compensating the shrinkage in

the casting.

为了使其有效，冒口应该遵循如下规则进行设计. 1、冒口中的金属应该最后凝固。 2、冒口体积应当足够进行铸件的补缩。

Table 5.6 volumetric liquid shrinkages Material Medium carbon steel High carbon steel

Nickel Monel Aluminum

Aluminum alloy (11-13% Si)

Aluminum bronze

Copper 70-30 brass Bearing bronze Grey cast iron White cast iron Magnesium Zinc

5.3.4.7 Chill 5.3.4.7 冷铁

In a casting, metallic chills are used in order to provide progressive solidification or to avoid the shrinkage cavities. Chills are essentially, large heat sinks. Whenever , it is not possible to provide a riser for a part of the casting which is heavy, a chill is placed close to it as shown in Fig. 5.29, so that more heat is quickly absorbed by the chill from the larger mass making the cooling rate equal to that of the thin sections. Thus, this dose not permit the formation of a shrinkage cavity. But use of a chill means essentially providing higher cooling rate which is also likely to form a hard spot at the contract area with the chill and may therefore cause a problem if that area needs further processing way of machining.

Shrinkage,(%) 2.50 to 3.50

4.00 6.10 6.30 6.60 3.50 4.10 4.92 4.50 7.30 1.90 to negative 4.00 to 5.75

4.20 6.50

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