Chapter 3 - Rolling of metals

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h h o Example: Calculate the rolling load if steel sheet is hot rolled 30% from a 40 mm-thick slab using a 900 mm-diameter roll. The slab is 760 mm wide. Assume µµµµ = 0.30. The plane-strain flow stress is 140 MPa at entrance and 200 MPa at the exit from the roll gap due to the increasing velocity. − h h ( 40) − ( h f o ∆h = f ( 40) = 28mm h o x100 = f − h From Eq.10 ) x100 = f = P 30% ( 40) 30 − ( 28) ' ⎡ 1 P = σ o ⎢ ( e ⎣Q = 12mm Q ⎡ 1 = 170⎢ ⎣( 0. 65) −1) b _ h Q σ ⎤ R∆h⎥ ⎦ = ' o = h Suranaree University <strong>of</strong> Technology Tapany Udomphol Jan-Mar 2007 o µ L _ h σ = + h 2 p = f µ ' entrance = ( 40) + ( 28) 2 R∆h _ h + σ 2 ' exit = 34mm ( 0. 30) 450x12 = ( 34) = 0. 65 140 + 200 = = 170MPa 2 0. 65 ⎤ ( e −1) ( 0. 76) 0. 45x0. 012 = 13. 4MN ⎥ ⎦
3) Sticky friction situation What would be the rolling load if sticky friction occurs? Continuing the analogy with compression in plane strain From Eq.8, From example; ⎛ = σ ⎜ ⎜ ⎝ ' P o _ ⎛ ⎞ ' ⎛ a ⎞ ⎜ L ' p p = σ ⎜ + 1⎟ = + 1⎟ o σ 0 ⎝ 2 ⎠ ⎜ _ h ⎟ ⎝ 4h ⎠ R∆h 4 _ h P = ⎞ + 1⎟b ⎟ ⎠ ⎛ 0. 45x0. 012 P = 170⎜ ⎜ ⎝ 4x0. 034 P = 14. 6MN _ p bL p R∆h ⎞ + 1⎟ ⎟ ( 0. 76) ⎠ 0. 45x0. 012 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 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: • Frictional force is needed to p
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

Chapter 3 - Rolling of metals

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