Chapter 3 - Rolling of metals

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Hot-rolling Hot rolling www.msm.cam.ac.uk Plate rolling • The first hot-working operation for most steel products is done on the primary roughing mill (blooming, slabbing or cogging mills). • These mills are normally two-high reversing mills with 0.6-1.4 m diameter rolls (designated by size). • The objective is to breakdown the cast ingot into blooms or slabs for subsequent finishing into bars, plate or sheet. • In hot-rolling steel, the slabs are heated initially at 1100 -1300 o C. The temperature in the last finishing stand varies from 700 - 900 o C, but should be above the upper critical temperature to produce uniform equiaxed ferrite grains. Suranaree University <strong>of</strong> Technology Tapany Udomphol Jan-Mar 2007
Example for hot strip mill process Red hot slab 210 mm thick is ready for rolling Slab is reduced to a long strip approx 25 mm thick Slabs are organised according to rolling schedule The strip is progressively reduced to the required thicknesses Plate 12 to 30 mm thick Coiled steel 1.8 to 12 mm thk 910 mm to 1550 mm wide Mill reverses after each pass (5 or 7) and the roll gap is reduced each time Leading edge and tail end are removed Strip is coiled and up ended or passed through if heavy plate Oxidation scale is removed www.nzsteel.co.nz The strip is coiled and uncoiled to make the tail end lead Suranaree University <strong>of</strong> Technology Tapany Udomphol Jan-Mar 2007
Page 1 and 2: Rolling of metals Subjects of inter
Page 3 and 4: www.world-aluminium.org Introductio
Page 5 and 6: Sheet rolling machines Rolled strip
Page 7 and 8: Rolls Mill rolls Mill rolls Suranar
Page 9 and 10: Typical arrangement of rollers for
Page 11 and 12: Typical arrangement of rollers for
Page 13 and 14: Different types of rolling processe
Page 15 and 16: Transverse rolling • Using circul
Page 17 and 18: Shaped rolling or section rolling A
Page 19 and 20: Simulation of ring rolling Simulati
Page 21 and 22: Powder rolling Metal powder is intr
Page 23: Thread rolling Cut thread and rolle
Page 27 and 28: Cold-rolling Cold rolling www.willi
Page 29 and 30: Cold-rolling Cold rolling • Cold
Page 31 and 32: h o Forces and geometrical relation
Page 33 and 34: • At only one point along the sur
Page 35 and 36: h o v o p A R N B h f Friction hill
Page 37 and 38: Therefore Free engagement will occu
Page 39 and 40: Problem with roll flattening When h
Page 41 and 42: Simplified analysis of rolling load
Page 43 and 44: 2) Normal friction situation In the
Page 45 and 46: • Frictional force is needed to p
Page 47 and 48: 3) Sticky friction situation What w
Page 49 and 50: Relationship of µµµµ, rolling l
Page 51 and 52: Problems and defects in rolled prod
Page 53 and 54: Uniform thickness • Under high ro
Page 55 and 56: Flatness • The roll gap must be p
Page 57 and 58: • Hot mill can be provided with f
Page 59 and 60: Possible effects when rolls are ove
Page 61 and 62: • Edging can also be caused by in
Page 63 and 64: Rolling mill control • Modern con
Page 65 and 66: Rolling load P3 P2 P1 Situation whe
Page 67 and 68: Thickness measurement in continuous
Page 69 and 70: The stresses acting on an element o
Page 71 and 72: The forces acting in the vertical d
Page 73 and 74: The rolling load or total force P i
Page 75 and 76:
Torque and power Torque is the meas
Page 77 and 78:
The torque M T is equal to the tota
Page 79:
References • Dieter, G.E., Mechan
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Chapter 3 - Rolling of metals

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