Chapter 3 - Rolling of metals

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Example: The previous example neglected the influence of roll flattening under very high rolling loads. If the deformed radius R ’ of a roll under load is given in Eq.11, using C = 2.16x10 -11 Pa -1 , P ’ =13.4 MPa from previous example. R ' ⎡ = R⎢ ⎢⎣ ( )⎥ ⎥ ' CP ⎤ + b ho − h f ⎦ 1 …Eq.11 6 ( 13. 4x10 ) ⎤ = 0. m −11 ' ⎡ 2. 16x10 R = 0. 45⎢1 + ⎥ 464 ⎣ 0. 76x0. 012 ⎦ Q P R '' '' µ R∆h = = _ h ⎡ 1 = 170⎢ ⎣0. 66 0. 30 0. 66 ( e −1) 464x12 34 0. 76 0. 66 −11 6 ⎡ 2. 16x10 ( 13. 7x10 ) ⎤ = 0. 45⎢1 + ⎥ = 0. 465m ⎣ 0. 76x0. 012 ⎦ = Where C = 16(1-νννν 2 )/ππππE ,P ’ = Rolling load based on the deformed roll radius. ⎤ 0. 464x0. 012⎥ ⎦ We now use R’ to calculate a new value of P ’ and in turn another value of R ’ 13. 7 Suranaree University of Technology Tapany Udomphol Jan-Mar 2007 = MN The difference between the two estimations of R ’ is not large, so we stop the calculation at this point.
Relationship of µµµµ, rolling load and torque x P r x N point : v roll = v sheet F N L p θ α β y y Friction acts in opposite directions Where µµµµ is obtained by measuring the torque and the rolling load at constant roll speed and reduction with the proper back tension. • We have known that the location of the neutral point N is where the direction of the friction force changes. • If back tension is applied gradually to the sheet, the neutral point N shifts toward the exit plane. • The total rolling load P and torque M T (per unit of width b) is given by P b M b = T thus µ = M ( µ pdx) Suranaree University of Technology Tapany Udomphol Jan-Mar 2007 L p ∫ 0 = PR pdx L o T p ∫ R = µ R L o p ∫ pdx = µ R P b
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 and 46: • Frictional force is needed to p
Page 47: 3) Sticky friction situation What w
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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