Chapter 3 - Rolling of metals

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• Surface defects are more easily in rolling due to high surface to volume ratio. Grinding , chipping or descaling of defects on the surface of cast ingots or billets are recommended before being rolled. • Laps due to misplace of rolls can cause undesired shapes. Roll misplacement • Flakes or cooling cracks along edges result in decreased ductility in hot rolling such as blooming of extra coarse grained ingot. • Scratches due to tooling and handling. • Variation in thickness due to deflection of rolls or rolling speed. Suranaree University of Technology Tapany Udomphol Jan-Mar 2007
Rolling mill control • Modern continuous hot-strip and cold rolling mills operated under automatic control provide high throughput and production rate. • Of all the metal working processes, rolling is the best suited for the adoption of automatic control because it is an essentially steady-state process in which the tooling geometry (roll gap) may be changed readily during the process. • Automatic control in rolling such as the development of online sensors to continuously measure sheet thickness. The most widely used instruments are 1) flying micrometer 2) x-ray or isotope, gauges which measure thickness by monitoring the amount of radiation transmitted through the sheet. • More recently control procedures have been aimed at controlling strip shape as well as thickness. Suranaree University of Technology Tapany Udomphol Jan-Mar 2007
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Rolling of metals Subjects of inter
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www.world-aluminium.org Introductio
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Sheet rolling machines Rolled strip
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Rolls Mill rolls Mill rolls Suranar
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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 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: • Edging can also be caused by in
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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