SME021_1P0434Rolling Process.ppt

7/28/2019 SME021_1P0434Rolling Process.ppt

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Instructional Design Document

Rolling Process

STAM Interactive Solutions


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Demo Outline (For reference)

Topic Number Topic Name Page Type

1 Introduction Animated page

2 Rolling Process Animated page

3 Roll Gap Animated page

4 Neutral Point Animated page

5 Position of Neutral Point Animated page

6 Simulation Interactive page


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Changes Suggested by Prof. Ramesh Singh Changes reflected on slide no.

1 Start with photo of real roll, voiceover to outline the process Slide 5 Also refer to the notes

section

2 Follow with schematic diagram listing processparameters (slide 15 of lecture notes atme.iitb.ac.in/~ramesh/me649/rolling.pdf)

Show pressure distribution on the schematic (free body diagram /stresses and forces)

Introduce neutral point

Slides 6, 7, 8 & 9 Also refer to thenotes section

3 Voiceover to introduce objective of instruction feasibility forreduction / power

Slide 4 Text & Voice over changed

4 Interactivity / animation Fix roll radius, back height and rotational speed of roll Enter hi and obtain maximum permissible hf Also show power required (using slides 35, 36, 55 and56 of above cited lecture notes)

Allow switch between 3 values for m: low, high andmedium (use 0.1, 0.2 and 0.4) Assume steel properties (perfectly plastic)

Slide10 - Also refer to the notessection

5 References Dont cite the wikipedia Add reference books as suggested

Slide 11

6 Modify quiz question 1 - Spelling: affect vs. effect

Modify quiz question 4 - All of above should be the correct answer

Slide 12 & 15

Change Log (as per the minutes pdf)


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Rolling ProcessAdvanced Manufacturing Process I & II

This demo illustrates the procedure for a 2-high

rolling mill. Calculation of the maximumreduction that can be achieved and the powerrequired to drive the rolling mill will beexplained.


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Rolling:

Is the process of plastically deforming metal by passing it betweenrolls Is widely used to convert steel ingots into blooms, billets, and slabs,and subsequently into plates, sheets and strips

Advantages: Provides high throughput Provides good control over the dimensions

of the finished product

In Hot Rolling: Metal is rolled at a temperature above itsrecrystallization temperature Higher reduction in the cross-section isachieved

In Cold Rolling: Metal is rolled at a temperature below its recrystallizationtemperature Better strength and control of dimensions are achieved

Introduction


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Rolling Process

Rolls transfer energy to the strip through friction. As the strip is dragged by the rolls into the gap

between them, it decreases in thickness while passing from the entrance to the exit. Meanwhile its speedgradually increases from the entrance to the exit.

V0 = input velocityVf= final or output velocityR = roll radiushb = back heighthf= output or final thickness


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Roll Gap

V0 = input velocityVf= final or output velocityR = roll radiushb = back heighthf= output or final thickness= = angle of biteL = Roll Gap


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Neutral Point

V0 = input velocity

Vf= final or output velocityR = roll radiushb = back heighthf= output or final thickness= = angle of biteN-N = neutral point or no-slippointL = Roll Gap

To the left of the Neutral Point:

Velocity of the strip < Velocity of the roll

To the right of the Neutral Point:

Velocity of the strip > Velocity of the roll


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Position of the Neutral Point

As the neutral point reaches the exit, the rolls skid over the strip and the strip will stop moving.

Maximum reduction is given by:


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Simulation

Back Height (hb):

START

Enter the parameters and click START.

Sheet

Roll

NeutralPoint

hb

R

hf

Rotational speed of Roll:

Roll Radius (R):

Final sheet thickness (hf):

Roll Gap (L):

2 mm Range (0.4mm to 10mm)

Friction Coefficient (): 0.1 Constant

Flow stress of steel (Yflow) 130 Mpa Constant

Width of the Roller (W): 10 mm Constant

75 mm Constant

0.8 m/s Constant

Force/Roller (F):

Power/Roller (P):

m:0.1 0.2 0.4


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Resources

Books:

Serope Kalpakjian & Steven R. Schmid, Manufacturing Process for EngineeringMaterials, Section 6.3 Rolling Process

Ghosh & Malik, Manufacturing Science


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The effect of friction on the rolling mill is

always bad since it retards exit of reduced metal

always good since it drags metal into the gapbetween the rolls

advantageous before the neutral point

disadvantageous after the neutral point


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As compared to cold rolling, hot rolling yields

better dimensional control and higher strength

better dimensional control but poorer strength

worse dimensional control and higher strength

better dimensional control and poorer strength


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Velocity at the exit is

higher than velocity at the entry

lower than velocity at the entry

either equal to or lower than velocity at the entry,depending on the coefficient of friction

either equal to or higher than velocity at the entry,depending on the coefficient of friction


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Power required depends upon

reduction of thickness

width of metal / rolls

coefficient of friction

metal type


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Reducing the rpm of the rolls

reduces the power required

has no affect on the power required

affects the power required depending on thecoefficient of friction

affects the power required depending on theproperties of the metal

Documents

SME021_1P0434Rolling Process.ppt