Chapter 3 - Rolling of metals

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Example for cold strip mill process. www.nzsteel.co.nz 20 tonne coils of cold rolled steel are dispatched to Metal Coating Line In batches of 9 coils, cold rolled steel is annealed to reduce work hardening The 6 roll configuration enables this high speed mill to produce steel of high quality with consistent shape and flatness Cold rolling mill Coils are transferred to and from the annealing furnace Cold rolling reduces the thickness and increases the strength of hot rolled steel. The surface finish and shape improve and work hardening results Coils up to 40 tones enter on a conveyor from the pickle line The combination mill has a dual function, cold rolling and single pass temper rolling Temper rolling improves the shape of the strip after its workability has been improved by annealing Cold rolled, annealed and tempered coils are transferred to the Cold Finishing Section Suranaree University of Technology Tapany Udomphol Jan-Mar 2007
Cold-rolling Cold rolling • Cold rolling provide products with superior surface finish (due to low temperature � no oxide scales) • Better dimensional tolerances compared with hot-rolled products due to less thermal expansion. • Cold-rolled nonferrous sheet may be produced from hot-rolled strip, or in the case of certain copper alloys it is cold-rolled directly from the cast state. Cold rolled metals are rated as ‘temper’ Cold rolled strips • Skin rolled : Metal undergoes the least rolling ~ 0.5-1% harden, still more workable. • Quarter hard : Higher amount of deformation. Can be bent normal to rolling direction without fracturing • Half hard : Can be bent up to 90 o . • Full hard : Metal is compressed by 50% with no cracking. Can be bent up to 45 o . Suranaree University of 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 and 24: Thread rolling Cut thread and rolle
Page 25 and 26: Example for hot strip mill process
Page 27: Cold-rolling Cold rolling www.willi
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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