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1、Rolling轧制轧制Rolling is the process of reducing the thickness(or changing the cross-section)of a long workpiece by compressive forces applied through a set of rolls(Fig.13.1);轧制是通过一些轧辊对一个长坯料进行加压使其厚度减薄或者界面形状发生变化的工艺。第1页/共57页The process is similar to the rolling of dough(面团）with a rolling pin（擀面杖）to redu
2、ce its thickness.Rolling,which accounts for about 90%of all metals produced by metalworking processes,was first developed in the late 1500s.The basic operation is flat rolling.扁平孔型轧制,or simply rolling,where the rolled products are flat plate and sheet.第2页/共57页Sheets are generally less than 6 mm thic
3、k.They are used for automobile and aircraft bodies,appliances(仪表),food and beverages(饮料）containers,and kitchen and office equipment.appliancesThe extrusion die is a steel disk with an opening,the size and shape of the intended cross-section of the final extruded product as indicated below.第3页/共57页Fl
4、at-and Shape-Rolling ProcessesFigure 13.1 Schematic outline of various flat-and shape-rolling processes.Source:American Iron and Steel Institute.Slab钢板Hot strip热轧带钢Pickling酸洗oiling润滑skelp制管钢板Pickling酸洗oling润滑bloom钢锭rail 铁轨Tube roundsPlates:t 6mmSheets:t0,and so|ex|ez|.Hence,a tension stress is gener
5、ated at the edges,to make the length at the edge equal to that at the center.This causes edge cracking,specially if ductility is low.Alligatoring occurs by a complex process.Aided by defects in the original casting.x yz第48页/共57页RESIDUAL STRESSESSmaller rolls tend to work the metal at the surfaces.Th
6、e metal extends on the surface.As the material comes out of the rolls,the central bulk region puts the extended surface in compression.This is similar to what occurs during shot peening.Large diameter rolls(often used in hot rolling)tend to work the central region more than the bulk.This is because
7、of higher friction at the surfaces.Consequently,the material is longer in the bulk than the surface,and a tension stress is generated at the surface.第49页/共57页FLAT ROLLING PRACTICEUse of Flattening RollsVarious Roll ArrangementsSendzimir Mill for Cold Rolling of Thin Sheets of High Strength Materials第50页/共57页SHAPE ROLLING 第51页/共57页RING ROLLING 第52页/共57页THREAD ROLLING 第53页/共57页计算机在塑性成形加工中的应用计算机在塑性成形加工中的应用第54页/共57页第55页/共57页第56页/共57页感谢您的观看。第57页/共57页