热加工专业英语.ppt

Induction Furnaces Because of their very rapid melting rates and relative ease of controlling pollution, the use of electric induction furnaces has increased extensively. Two types are used. The high-frequency type, or coreless induction furnace, shown in Fig.2-10-4, consists of a crucible surrounded by a water-cooled coil of copper tubing. A high-frequency electrical current passes through the coil, establishing an alternating magnetic field, which, in turn, induces secondary currents in the metal in the crucible. These secondary currents heat the metal very rapidly. 感应电炉 水冷线圈 磁场 These furnaces are used for virtually all common alloys, the maximum temperature being limited only by the refractory and efficiency of insulating against heat loss. They provide good control of temperature and composition and are available in capacities through 65 tons. Because there is no contamination from the heat source, they produce very pure metal. Low-frequency, or channel-type, induction furnaces are being used increasingly. As indicated in Fig.2-10-5, these have an ordinary alternating-current primary coil, but the secondary coil is formed by a loop, or channel, of the molten metal. Because the secondary coil has but one turn, a low voltage/high amperage current is induced in it, which provides the desired heating. Some molten metal, to form the secondary coil, must be used to start such furnaces, but their heating rate is very high, and the temperature is readily controlled. This makes them very useful, and widely used, as holding furnaces, where it is desired to maintain molten metal at a constant temperature for an extended period of time, as in die-casting machines or in mold-pouring systems. Capacities are available up to 250 tons. Fig.2-10-4 Cross-sectional view of a high-frequency induction furnace Fig.2-10-5 Principle of the low-frequency induction furnace Summary 掌握必须的专业单词（New Words） 掌握常用的专业术语（Glossary of Terms) 掌握基本的语法知识 掌握基本的翻译技巧 References 书名：热加工专业英