Е. С. Закирова, П. А. Красавин Английский язык для технических вузов
Exercise 31. Compile information about metal forming processes and partici-
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- ROLLING, EXTRUSION, DRAWING
| Exercise 31. Compile information about metal forming processes and partici-
pate in a project. Present the project to your group. You may use the fol- lowing website: www.qcforge.info/Page.aspx/89/Forging_Questions.html ADDITIONAL READING Exercise 32. Make a summary of the text using the following phrases: 1. The title of the text is… 2. The text is about… The text deals with… 3. The text covers such points as… first… second… third… 4. It should be underlined that… 5. In conclusion, I may say that… 6. To my mind… In my opinion… 155 ROLLING, EXTRUSION, DRAWING Rolling is a metal forming process in which metal stock is passed through a pair of rolls to achieve the fixed shapes and properties. Rolls are revolving at the same speed but in opposite directions; they are spaced so that the dis- tance between them is slightly less than the thickness of the metal. Rolling is classified according to the temperature of the metal rolled. If the tempera- ture of the metal is above its recrystallization temperature, then the process is termed as hot rolling. If the temperature of the metal is below its recrystalliza- tion temperature, the process is termed as cold rolling. Rolling is particularly important in the manufacture of steel. Extrusion is a process used to create objects of a fixed cross- sectional pro- file: a material is pushed or drawn through a die of the desired cross section. The two main advantages of this process over other manufacturing processes are its ability to create very complex cross sections from materials that are brit- tle and to form finished parts with an excellent surface finish. The extrusion process can be done with the material hot or cold. Commonly extruded mate- rials embrace metals, polymers, ceramics, etc. Plastics extrusion is a high vol- ume manufacturing process in which raw plastic material is melted and formed into a continuous profile. Rolling Extrusion 156 Drawing is a metalworking process which uses tensile forces to stretch metal. For wire, bar, and tube drawing, the starting stock is drawn through a die to reduce its diameter and increase its length. Drawing is usually done at room temperature, thus classified as a cold working process; however, it may be performed at elevated temperatures in order to reduce forces. Drawing жүктеу/скачать 4,38 Mb. Достарыңызбен бөлісу:
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