calculation of % slip in mill during rolling by ajmal(10.09.2014)

7/25/2019 Calculation of % Slip in Mill During Rolling by Ajmal(10.09.2014)

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CALCULATION OF % SLIPIN MILL DURING ROLLING

02.07.2010


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Copyright 2010 Jindal Steel & Power Ltd.2

CALCULATION OF % SLIP IN MILL

DURING ROLLINGSLIPDuring rolling there is always present a fator !nown asslip.Slip is the di"erene #etween wor! roll iru$ferentialspeed and the linear speed of the #ar % it depends on

$any fators suh as entry and eit ross'setion% #a!and front $etal tension and frition ondition.

Slip are of two types1. Forward slip( if the linear speed of the $aterial is

greater than roll iru$ferential speed the slip is forwardslip.2. Backward slip( if the linear speed of the $aterial isless than roll iru$ferential speed the slip is #a!wardslip.


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CALCULATION OF % SLIP IN MILL DURING

ROLLING

1. )hat lead speed perentage should #e !ept for

inter$ediate and #ra!ing pinh rolls% so that thereshould #e no *uttering in the $aterial *ow and di+ideut should #e proper and lear.

,--

C/S

2. he rop length head ut & tail ut3 in Shear41 wasnot onsistent with respet to operator5s edita#le data

in 68 Sreen.

Slip ontinuously +aries #ased on $any types of physialondition. 9ollowing are the #roadly ategori:ed physialonditions.

1.)ear & tear of roll.2.ension in #etween stands.3.e$perature of $aterial.

EFFECT OF THE SLIP DURING ROLLING

RE!


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ROLLING

"#a$ l%ad sp%%d p%rc%&$a'% s#o(ld )% k%p$ *ori&$%r+%dia$% a&d )raki&' pi&c# rolls, so $#a$ $#%r%s#o(ld )% &o -($$%ri&' i& $#% +a$%rial -ow a&d

di.id% c($ s#o(ld )% prop%r a&d cl%ar/


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ROLLING

INTRODUCTION

Pinh rolls are pro+ided to reate proper tension in the

$aterial so that $aterial easily tra+els through water #oes

and there should #e enough proper tension for di+ide shearto

ta!e proper and lear ut.

0ESURE0ENT

)e atually alulate the atual linear +eloity of the

$aterial with the help of two 6Ds 12 and 1;3. /nd weha+e the linear +eloity of rst inter$ediatepinh roll. 9irst pinh roll after


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ROLLING

CLCULTION

Distane #etween 6D 12 to 1; ? ;@.A $ts


7/15Copyright 2010 Jindal Steel & Power Ltd.7


ROLLING

So the lead for the >rst inter$ediate pinh roll should #eslightly

greater than the alulated +alue.

Calulated is A.0@E so it should #e !ept around A.1E. 9or

net pinhroll this should slightly higher then the >rst.

his alulation is auto$atially done in the pl and displayedin the

68.

his #eo$es the referene for the operator.

8f physial ondition hanges so the slip and the lead shouldalso #e

hanged to $ath the atual speed of the $aterial.




ROLLING




ROLLING

T#% crop l%&'$# #%ad c($ $ail c($ i& S#%ar41was &o$ co&sis$%&$ wi$# r%sp%c$ $o op%ra$or5s%di$a)l% da$a i& H0I Scr%%&.




ROLLING8n S8,-LL Sie$ens rolling ehnology3 for any rolled produt the

ross setion of the $aterial at stand4F re$ains onstantirrespeti+e of any si:e $$ to ;0$$3 of $aterial to #e rolled. Gased on that S8,-LL Sie$ens rolling ehnology3has adopted a >ed slip fator of 2E in the $ill logi.)e ha+e o#ser+ed that the slip ontinuously +aries fro$ 2E'E#ased on $any types of physial ondition. 9ollowing are the#roadly ategori:ed physial onditions.1.)ear & tear of roll.2.ension in #etween stands.B.e$perature of $aterial.

"HT DONE TO 06E IT CONSISTENTCAPTURING THE ACTUAL MATERIAL

SLIP

8t was neessary to $easure the slip for e+ery #illet for utlength onsisteny.

9or this we re=uired two physial loation and the referene+eloity of stand4F% the two physial loations are Stand4F and




ROLLINGCONCEPT

Based on this slip calculation the speed of the material isdetermined at the shear. And as the HMD 05 senses thehead it calculates the time to trigger the shear. Since theslip is not the same in every billet as discussed above sothe trigger time also varies to make the head cutconsistent.




ROLLING

0a$#%+a$ical calc(la$io&onsider!elocity reference of stand"# $ !m%s &from plc'Distance bet(een stand"# to HMD 05 $ D m)ime to travel bet(een stand"# and HMD 05 $ ) sec.

*o( the slip is calculated as

Actual material velocity $ D%)$!act m%s &say'

+ slip $ &,-&!act%!'',00

)his sli is no( multi lied to stand"# velocit to make


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ROLLING

Suppose operator sets the head cut length $ mDistance bet(een HMD05 to SH 0, $1 mSo total length passed (hen shear blade bites the material to cut

2 mtr from HMD 05$ 31 m

)ime re4uired for 2 mtr material passes from the SH0, position&),'

$ &31'%/

Suppose time taken by the shear to travel from pass line positionto cut position

$ )

So Sh0, trigger time after HMD 05 head senses &)'$ ),-)


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Copyright 2010 Jindal Steel & Power Ltd.

)hank you

calculation of % slip in mill during rolling by ajmal(10.09.2014)

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