锤子ROM智能手机操作系统发布会(完整版).ppt

毕业设计(论文)外文翻译
学生姓名:
系别: 机械工程系
专业: 机械设计制造及其自动化
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学号:
译文出处:Science and Technology Engl-
ish for Mechanical Engineering
Casting、Forging and Welding
1. Casting
Metal casting is one of the oldest of all industries, both ancient and medieval history offering examples of the manufacture and use of casting. From simple axeheads poured from copper in open moulds some 5000 years age, casting in the pre-Christian world developed to a point at which elaborate bronze statuary could be produced in two-piece and cored moulds. By the end of the medieval period, decorated bronze and pewter casting had begun to be used in European church and domestic life.
The widespread adoption of cast iron as engineering material awaited the ess of Abraham Darby in 1790 in smelting in the coke blast furnace; this paved the way for the massive use of cast iron in construction during the years following the industrial revolution.
Many foundries sprang up after the industrial revolution, the vast majority being for the manufacture of the cast iron then being used as a structural material. The quantity production of iron castings in the eenth century was not matched by a universal advance in quality and the engineering use of the products encountered more serious risks in a non-ductile material.
Despite the skill of the molder in plex forms, there was little change in the metallurgical and engineering situation until the modern era brought a better understanding of the factors determining quality. With modern techniques of process control the rudimentary judgment of the operator could give way to objective measurements of metal temperature, molding material properties and other production variables. These improvements have been applied not only to cast iron but to a wide range of cast alloys.
There are four basic casting methods: sand-casting, die-casting, investment-casting, and centrifugal casting.
Sand-casting is the most widely used method employed in foundry. In this process,