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安放砂芯来制成铸件的凹形结构或内部特征。为了以后铸模匹配还要用到定位销。对大质量铸件可能需要加入冷却物来使其较快冷却。
5. The patterns are removed, and the molds may be put through a baking stage to increase strength.
6. Mold halves are mated and prepared for pouring metal. 5. 取走型模，将铸模烘焙以增加强度。 6. 匹配上下铸模，做好浇铸金属的准备。
7. Metal is preheated in a furnace or crucible until is above the liquidus temperature in a suitable range (we don’t want the metal solidifying before the pour is complete). The exact temperature may be closely controlled depending upon the application.
7. 金属在熔炉或坩埚中预热到高于液化温度的一个合适范围内(不希望金属在浇铸完成前凝固)。确切的温度要根据应用场合严格控制。
Degassing, and other treatment processes may be done at this time, such as removal of impurities (i.e. slag). Some portion of this metal may be remelted scrap from previously cast parts—10% is reasonable.
在此期间还要进行排气和其它处理步骤，例如去除杂质(即熔渣)。可以加入一定量原先是这种金属铸件的废料再融化—10%是适当的。
8. The metal is poured slowly, but continuously into the mold until the mold is full. 9. As the molten metal cools (minutes to days), the metal will shrink and the volume will decrease. During this time molten metal may backflow from the molten risers to feed the part and maintain the same shape. 8. 将金属缓慢而连续地注满型模。
9. 随着熔化金属的冷却(几分钟到几天)，金属收缩体积减小。在此期间熔化金属可能从冒口回流供给零件以保持其形状不变。
10. Once the part starts to solidify small dendrites of solid material form in the part. During this time metal properties are being determined, and internal stresses are being generated. If a part is allowed to cool slowly enough at a constant rate then the final part will be relatively homogenous and stress free.
10. 在零件开始凝固其内部形成固态金属的小型树枝状结晶期间金属性能被确定，同时也产生了内应力。如果零件以恒定速率冷却得足够缓慢，最终零件将相对均质并释放内应力。
11. Once the part has completely solidified below the eutectic point it may be removed with no concern for final metal properties. At this point the sand is simply broken up, and the part removed. At this point the surface will have a quantity of sand adhering to the surface, and solid cores inside.
11. 一旦零件在共析点以下完全凝固，可以不考虑金属的最后性能而将其取出。这时可以简单地打碎砂型并取出零件，但零件表面会有大量型砂粘附着，内部还有实心的砂芯。
12. A bulk of the remaining sand and cores can be removed by mechanically striking the part.
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Other options are to use a vibrating table, sand/shot blaster, hand labor, etc.
12.大量的剩余型砂和砂芯要通过机械敲击零件来去除。其它的选择还有采用振动台、喷砂/喷丸机、手工作业等等。
13. The final part is cut off the runner gate system, and is near final shape using cutters, torches, etc. Grinding operations are used to remove any remaining bulk.
14. The part is taken down to final shape using machining operations. And cleaning operations may be used to remove oxides, etc.
13. 最后零件要用刀具、喷枪等切掉浇道闸道系统，这样就接近最终形状了。再用磨削作业去除多余的部分。
14. 通过机加工将零件切削到最终形状。可能还要用清洗作业去除氧化物等。
? Investment casting
熔模铸造
Investment casting is also known as the lost wax process. This process is one of the oldest manufacturing processes. The Egyptians used it in the time of the Pharaohs to make gold jewelry (hence the name Investment) some 5,000 years ago.
熔模铸造也称为失蜡加工。这是最古老的制造工艺之一。大约在5,000年前的法老王时代，埃及人就用它制造黄金饰品(因此而得名投资)。
Intricate shapes can be made with high accuracy. In addition, metals that are hard to machine or fabricate are good candidates for this process. It can be used to make parts that cannot be produced by normal manufacturing techniques, such as turbine blades that have complex shapes, or airplane parts that have to withstand high temperatures.
复杂的形状能被高精度地制造。另外较难机加工或制作的金属都能用此工艺。它还能用于生产一般制造技术无法生产的零件，例如有复杂形状的涡轮叶片或必须耐得住高温的飞机零件。
The mold is made by making a pattern using wax or some other material that can be melted away. This wax pattern is dipped in refractory slurry, which coats the wax pattern and forms a skin. This is dried and the process of dipping in the slurry and drying is repeated until a robust thickness is achieved.
制作铸型的型模采用石蜡或其它一些能被融化掉的材料做成。石蜡型模浸泡在耐热浆里，让它覆盖型模并形成外壳，然后使其变干。重复这个浸泡、变干的过程直至获得足够的厚度。
After this, the entire pattern is placed in an oven and the wax is melted away. This leads to a mold that can be filled with the molten metal. Because the mold is formed around a one-piece pattern (which does not have to be pulled out from the mold as in a traditional sand casting process), very intricate parts and undercuts can be made.
完成后把整个型模放在烤箱里融化石蜡。这样就做成了能填充熔化金属的铸型。由于这种铸型是环绕整块型模形成的(无需像传统的砂型铸造工艺那样拔模)，能制作十分复杂的零件和浮雕。
The wax pattern itself is made by duplicating using a stereo lithography or similar model—which has been fabricated using a computer solid model master.
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石蜡型模本身能用立体制版或类似的模型复制—这可以采用计算机立体模型原版制作。
The materials used for the slurry are a mixture of plaster, a binder and powdered silica, a refractory, for low temperature melts. For higher temperature melts, sillimanite or alumina-silicate is used as a refractory, and silica is used as a binder.
对较低熔化温度而言，用于耐热浆的材料是石膏作粘合剂和用粉末状硅石作耐温材料的混合物。对较高熔化温度而言，则采用硅线石或氧化铝硅酸盐作耐温材料、无水硅酸作粘合剂。
Depending on the fineness of the finish desired additional coatings of sillimanite and ethyl silicate may be applied. The mold thus produced can be used directly for light castings, or be reinforced by placing it in a larger container and reinforcing it more slurry.
根据最后所需光洁度也可采用硅线石和乙烷基硅酸盐。这样生成的铸模可直接用于薄壁铸件或通过将其放在较大容器内用更多耐热浆加强。
Just before the pour, the mold is pre-heated to about 1,000℃(1,832℉) to remove any residues of wax, harden the binder. The pour in the pre-heated mold also ensures that the mold will fill completely.
在正要浇铸之前，将型模预热到约1,000℃(1,832℉)以去除剩余石蜡、硬化粘合剂。在预热的型模中浇铸也能保证型模完全充满。
Pouring can be done using gravity, pressure or vacuum conditions. Attention must be paid to mold permeability when using pressure, to allow the air to escape as the pour is done. 浇铸可采用重力、压力或真空条件来实现。当使用压力时必须注意渗透性，以便在浇铸的同时让空气逸出。
Tolerances of 0.5% of length are routinely possible, and as low as 0.15% is possible for small dimensions. Castings can weigh from a few grams to 35kg (0.1oz to 80lb), although the normal size ranges from 200g to about 8kg(7oz to 15 lb). Normal minimum wall thicknesses are about 1mm to about 0.5mm(0.040~ 0.020 in.) for alloys that can be cast easily.
一般公差可能为长度的0.5%，小尺寸可能低到0.15%。虽然通常尺寸的铸件重量范围为200g到约8kg(7oz到15lb)，但实际可从几克到35kg (0.1oz to 80lb)。对容易铸造的合金而言，通常壁厚约为1mm到0.5mm(0.040~ 0.020 in.)。
The types of materials that can be cast are aluminum alloys, bronzes, tool steels, stainless steels, stellite, hastelloys, and precious metals. Parts made with investment castings often do not require any further machining, because of the close tolerances that can be achieved.
可以用于铸造的材料类型有：铝合金、青铜、工具钢、不锈钢、钨铬钴合金、镍基合金和贵金属。采用熔模铸造的零件常常不需要进一步加工，因为熔模铸造能达到精密的公差。
? Centrifugal Casting
离心铸造
Centrifugal casting (Fig.3.3) as a category includes centrifugal casting,
semi-centrifugal casting and centrifuging. In centrifugal casting, a permanent mold is rotated
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about its axis at high speeds (300 to 3,000rpm) as the molten metal is poured.
离心铸造(图3.3)作为一个种类包括了离心铸造、半离心铸造和离心法铸造。离心铸造中，永久性的型模在熔化金属浇铸时以较高速度(300到3,000rpm)绕其轴线旋转。
The molten metal is centrifugally thrown towards the inside mold wall, where it solidifies after cooling. The casting is usually a fine grain casting with a very fine-grained outer diameter, which is resistant to atmospheric corrosion, a typical situation with pipes. The inside diameter has more impurities and inclusions, which can be machined away.
受离心力作用熔化金属被抛向型模的内壁，在那里冷却后固化。这种铸件通常为外径处晶粒非常细小的细晶粒铸件，能耐大气腐蚀，典型的情况是管子。内径处则有较多的杂质和内含物，但可用机加工去除。 Only cylindrical shapes can be produced with this process. Size limits are up to 3m(10feet) diameter and 15m(50 feet) length. Wall thickness can be 2.5mm to
125mm(0.1~5.0in.). The tolerances that can be held on the OD can be as good as 2.5mm (0.1in.) and on the ID can be 3.8mm(0.15in.). The surface finish ranges from 2.5mm to 12.5mm(0.1~0.5in.) rms(root-mean-square).
只有圆柱形才能用此工艺生产。尺寸限制为直径大到3m(10feet)、长度大到15m(50feet)。壁厚为2.5mm到125mm(0.1~5.0in.)。外径公差保持在2.5mm(0.1in.)以内，内径公差保持在3.8mm(0.15in.)以内。表面粗糙度的有效值(均方根)范围为2.5mm到12.5mm(0.1~0.5in.)。
Typical materials that can be cast with this process are iron, steel, stainless steels, and alloys of aluminum, copper and nickel. Two materials can be cast by introducing a second material during the process. Typical parts made by this process are pipes, boilers, pressure vessels, flywheels, cylinder liners and other parts that are axis-symmetric.
可用此工艺铸造的典型材料有：铁、钢、不锈钢以及铝、铜和镍的合金。通过在生产过程中加入第二种材料能进行两种材料铸造。采用这种工艺制造的典型零件有：管子、锅炉、压力容器、飞轮、汽缸衬垫和其它轴对称零件。
Semi-centrifugal casting. The molds used can be permanent or expendable, can be stacked as necessary. The rotational speeds are lower than those used in centrifugal casting. 半离心铸造：型模可以是永久性的或是消耗性的，可根据需要叠加。它的旋转速度比离心铸造低。 The center axis of the part has inclusion defects as well as porosity and thus is suitable only for parts where this can be machined away. This process is used for making wheels, nozzles and similar parts where the axis of the part is removed by subsequent machining.
零件的中心轴附近存在缺陷和孔隙，因此仅适用于能将这些机加工去除的零件。这种工艺被用于制造车轮、管嘴及类似的随后可用机加工去除中心轴部分的零件。
Centrifuging. Centrifuging is used for forcing metal from a central axis of the equipment into individual mold cavities that are placed on the circumference. This provides a means of increasing the filling pressure within each mold and allows for reproduction of intricate details. This method is often used for the pouring of investment casting pattern.
离心法铸造：离心法铸造用于迫使金属从设备的中心轴进入分布在圆周上的单独型腔。它为每个
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型腔提供了一种增加填充压力方法并允许再现复杂细节。这种方法常用于浇铸熔模铸型。
Full-mold casting is a technique similar to investment casting, but instead of wax as the expendable material, polystyrene foam is used as the pattern. The foam pattern is coated with a refractory material. The pattern is encased in a one-piece sand mold. As the metal is poured, the foam vaporizes, and the metal takes its place.
实型铸造是与熔模铸造类似的技术，但它用做型模的消耗材料是聚苯乙烯泡沫而不是石蜡。泡沫型模用难熔材料覆盖。型模装入整体砂模中。当金属浇入时，泡沫材料蒸发，金属取代其位置。 This can make complex shaped castings without any draft or flash. However, the pattern cost can be high due to the expendable nature of the pattern. Minimum wall thicknesses are 2.5mm, tolerances can be held to 0.3% on dimensions. Surface finish can be held from 2.5μm to 25μm(0.1μin. to 1.0μin.) rms(root-mean-square).
它能制造没有拔模斜度和缝脊的复杂形状铸件。然而由于型模的消耗特性，型模成本可能较高。最小壁厚为2.5mm，公差能保持在尺寸的0.3% 之内。表面粗糙度的有效值(均方根)能保持在2.5μm至25μm(0.1μin.至1.0μin.)之间。
Size limits are from 400g(1lb) to several tons. No draft allowance is required. Typical materials that can be cast with this process are aluminum, iron, steel, nickel alloys, copper alloys. Types of parts that can be made using these processes are pump housings, manifolds, and auto brake components.
重量限制从400g(1lb)到数吨。无需留拔模余量。这种工艺所用的典型材料有：铝、铁、钢、镍合金、铜合金。可以采用这些工艺制造的零件类型有泵壳、复式接头和自动刹车部件。
第四单元
? Introduction 引言
Forging is an important hot-forming process. It is used in producing components of all shapes and sizes, from quite small items to large units weighing several tons.
锻造是一种重要的热成型工艺。它能用于生产各种形状和尺寸、从很小到重量数吨的零件。 Forging is the process by which metal is heated and is shaped by plastic deformation by suitably applying compressive force. Usually the compressive force is in the form of hammer blows using a power hammer or a press, as shown in Fig.4.1.
在锻造过程中先将金属加热，然后施加合适的压力使其塑性变形。通常压力都是以由如图4.1所示
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机械工程英语第二版全本书中英对照翻译
