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  2. 2. A typical product Powder metal filters Ceramic Spark plugs Drawn Shaped Moulded tube for Forged wind shield dash board antenna valves Cold-rolled Sheet metal or Reinforced plastic For body Stamped license plates Stamped Wheel covers Stamped Blow-moulded oil pan Windshield Washer fluid tank Injectionmoulded Tail light lens Springs Fuel tank Compression Moulded tires Fig. 1 Formed and shaped parts in a typical automobile
  3. 3. Rolling Hot strip Picking and coiling Cold strip Welded pipe Skelp Plate Slab Steel plates Continuous casting or ingots Cold drawn bars Hot-rolled bars Billet Rods Wire and wire products Tube rounds s sfft g Seamless pipe Bloom --------------- Structural shapes Rails Fig.2 Schematic outline of various flat-and shape-rolling processes
  4. 4. A few products of the rolling process Fig. 2a
  5. 5. A typical rolling process Fig. 2b
  6. 6. Flat rolling process Top roll removed Wo ho Va Vr R F Roll Work piece Vf No-roll Point Vo Wf Roll Vr hf Fig. 3a Schematic illustration of the flat-rolling processes a Vf Work piece Friction forces Entry zone Roll Gap L Exit zone Torque Fig. 3b Fig. 3c Friction forces acting Roll force F and torque on strip surfaces Acting on the rolls Note: The width of the strip usually increases during rolling
  7. 7. Roll deflections Rolls Strip thicker at entrance Fig.4a Bending of straight cylindrical rolls caused by the roll force Strip with Uniform thickness Fig. 4b Bending of rolls ground with Camber, producing a strip with uniform thickness
  8. 8. Four-high rolling-mill stand Screw or Hydraulic mechanism Housing Back-up rolls Chocks Work rolls Back-up rolls Fig.5 Schematic illustration of a four-high rolling-mill stand, showing its various features. The stiffness of the housing, rolls, and roll bearings are important in controlling and maintaining the thickness of the rolling strip.
  9. 9. Rolling Fig. 5a Schematic illustration of rolling process with axis of roller in vertical
  10. 10. Rolling Fig. 5b Schematic illustration of rolling process with axis of roller in horizontal
  11. 11. A rolling Machine Fig. 5c
  12. 12. Spreading Side view Top view Fig. 6 Increase in width (Spreading) of a strip in flat rolling. Spreading can be similarly observed when dough is rolled with two rolling pin.
  13. 13. Hot rolling Hot rolling Ingot With nonuniform grains Wrought Product with Large grains Deformed Elongated grains New grains forming New grains growing Recrystallization complete Wrought Product with Small, uniform grains Fig.7 Change in the grain structure of cast or large-grain wrought metals during hot rolling. Hot rolling is an effective way to reduce grain size in metals for improved strength and ductility. Cast structures of ingots or continuous castings are converted to a wrought structure by hot working.
  14. 14. Leveling Sheet Leveling rolls Fig. 8 A method of roller leveling to flatten rolled sheets
  15. 15. Defects in Flat rolling Fig. 9a Wavy edges Fig.9c Edge cracks Fig. 9b Zipper cracks in the center of the strip Fig. 9d alligatoring
  16. 16. Residual stresses Sheet thickness Tension Compression Fig.10a Residual stresses developed in rolling with small rolls or at small small reductions in thickness per pass Tension Compression Fig. 10b Residual stresses developed in rolling with large rolls or at high reductions per pass Note: The reversal of the residual stress patterns.
  17. 17. Surface roughness Roughness (Ra) Process Sand casting Hot rolling Average application Less frequent application Forging Permanent mould casting Investment casting Extruding Cold rolling, drawing Die casting Fig. 11 Surface roughness in various metal working and casting process. Note: The large difference in hot and cold rolling
  18. 18. Rolling mills Fig.12c Fig.12a Two-high Fig.12b four-high three-high Fig.12d Cluster (sendzimir) mill Schematic illustration of various roll arrangements
  19. 19. A tandem rolling operation Stand 1 30 2 17.7 3 10.7 4 6.6 5 4.1 m/s Take-up reel Pay-off reel 0.26 0.34 0.56 0.90 Fig. 13 1.45 2.25 mm
  20. 20. Shape-Rolling operations Stage 1 Blooming rolls Stage 4 Intermediate horizontal and vertical rolls Stage 2 Edging rolls Stage 5 Edging rolls Stage 3 Roughing horizontal and vertical rolls Stage 6 Finishing horizontal and vertical rolls Fig. 14 Stages in shape rolling of an H-section part. Various other structural sections, such as channels and I-beams, are also rolled by this process
  21. 21. Ring rolling Idler roll Work piece Main roll (driven) Fig.15b Examples of cross sections that can be formed by ring rolling Edging roll Fig. 15a Schematic illustration of a ring rolling operation Note: Thickness reduction results in an increase in the part diameter
  22. 22. A typical ring rolling process Fig. 15c
  23. 23. Production of tapered ring Step 1 Sheared to length Step 2 Pancaked Step 3 Prepunched and preformed Step 4 Punched and restruck Step 5 Ring rolled Fig 16 Stages in the production of a tapered ring, using a combination of Forming process. The sequence shown in steps 2-4 is a common method of producing holes in relatively small parts.
  24. 24. Thread rolling Moving die Threaded part Stationary die Stationary Cylindrical die Blank Fig. 17a Work Moving cylindrical die Fig. 17c Force Work rest Fig. 17b Fig. 17a &17c reciprocating flat dies Fig. 17b two-roller dies Note: Threaded fasteners, such as bolts, are made economically By these processes at high rates of production.
  25. 25. Thread rolling Diameter of blank Diameter of bar Minar Major diameter diameter Machined thread Rolled thread Fig.18a Differences in the diameters of machined and rolled threads Machined thread Rolled thread Fig.18b Grain flow in machined and rolled threads. Unlike machining, which cuts through the grains of the metal, rolled threads have improved strength because of cold working and favourable grain flow.
  26. 26. Production of seamless tubing and pipe Rolls Mandrel Tube Solid bar Fig. 19 Cavity formation in a solid round bar and its utilization in the rotary tube Piercing process for making seamless pipe and tubing Fig. (a) round bar is subjected to radial compressive forces Fig. (b) a cavity begins to form at the center of the bar Fig. (c) rotary tube pierzing is carried out using an arrangement of rotating rolls.
  27. 27. Tube rolling processes Roll Roll Mandrel Work piece Rod Work piece Mandrel rod Fig. 20a fixed mandrel Fig. 20b moving mandrel Pilger roll Roll Work piece Mandrel Work piece Fig. 20c rolling without mandrel Fig. 20d Note: tube diameters and thickness pilger rolling over a mandrel and Can also be changed by other processes a pair of shaped rolls Such as drawing, extrusion & spinning
  28. 28. Direct casting of sheet and plate steel Tundish Tundish Substrate Argon hood Water jets Mould plate Tundish Block Side dams Tundish Knife Fig.21 Examples of direct casting techniques under development for economical production of plate and sheet
  29. 29. Spray casting Induction –heated ladle Atomizer (nitrogen gas) Recipient substrate Tube Deposition chamber Fig. 22 Spray casting (osprey process) in which molten metal is spayed Over a rotating mandrel to produce seamless tubing and pipe.
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