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The Processes of Metalworking Metals are by important in the industry for They Because the BE CAN Easily Into Useful deformed shapes. A lot of metalworking processes have been developed for certain applica¬tions. They can be divided into five broad groups : 1. rolling, 2. extrusion, 3. drawing, 4. forging, 5. metal-forming sheet. During working the first a four Processes metal is subjected to large Amounts of strain (deformation). But if deformation goes at a high temperature , the metal will recrystallize - that is, new strain-free grains will grow instead of deformed grains. For this reason metals are usually rolled, extruded, drawn, or forged above their recrystallization temperature. This is called hot working. For These conditions there Under the no is the limit to the compressive plastic strain to the which the metal subjected the BE CAN. Other Processes are Performed the below the recrystallization temperature. These are called cold working. Cold working hardens metal and makes the part stronger. HOWEVER, there is a the limit to the strain the before a cold part cracks. The Rolling the Rolling is the are most common all metal working process. More than 90 percent of the aluminum, steel and copper produced is rolled at least once in the course of produc¬tion. The most common rolled product is sheet. Rolling can be done either hot or cold . The rolling is the If the finished cold, the surface will of the BE smoother and stronger the product product. Extrusion Extrusion is pushing the billet to flow through the orifice of a die. Products may have either a simple or a complex cross section. The frames are window Aluminium the examples of the complex extrusions. Tubes or hollow parts OTHER CAN Also the BE extruded. Of The initial piece is a the thick format-the walled tube, and the extruded part is shaped Between a die on the outside of the tube and a mandrel Held on the inside. With In impact extrusion (Also Called back-extrusion) (extruding), the workpiece is placed in the bottom of a hole and a loosely fitting ram is pushed against it. The ram forces the metal to flow back around it, with the gap between the ram and the die determining the wall thickness. Of the this example of The process is the manufacturing of Aluminium cans of beer. Exercises Exercise 1.General Understanding: 1. Why are metals so important in industry? 2. What are the main metalworking processes? 3. Why are metals worked mostly hot? 4. What properties does cold working give to metals? 5. What is rolling? Where is it used? 6. What is extrusion? What shapes can be obtained after extrusion? For What are the 7. types of extrusion? Exercise 2. the following in the Find the the text: 1. can easily deform the desired shape 2. 3. subjected to large deformations 3. Grain-free deformation recrystallization temperature 4. 5. 6. plastic compression deformation of the most common metal processing 7. The most common product is rolled the die orifice 8. 9. 10. The original complex 11. The cross-section of the hollow parts 12 free incoming plunger 13. The gap between the plunger (punch) and a stamp of the wall thickness 14. Exercise 3. Translate into English: 1. The ability to recrystallize the metal at high temperature used in hot working. 2. Recrystallization - is the growth of new, strain-free grains. 3. During the heat treatment the metal may be exposed to very high plastic strain ratio. 4. The cold treatment makes the metal harder and more durable, but some metals have a limit of deformation. 5. Steel sheets can be made hot or cold. 6. The surface of the cold rolled sheet is smoother and stronger than he. 7. The cross-section of the die extrusion can be simple or complex. 8. Aluminum and copper alloys are the best for extrusion because of their plasticity when deformed. 9. Aluminum cans, tubes for toothpaste are examples of use extrusion forming. 10. The wall thickness of the aluminum cans defined gap between the punches and dies.
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