17283346 Theory of Metal CuttingTheory of Chip Formation

8/12/2019 17283346 Theory of Metal CuttingTheory of Chip Formation

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LECTURE-07THEORY OF METAL CUTTING

- Theory of Chip Formation

NIHIL R! "HAR# $h! "!DEPARTMENT OF INDUSTRIAL & PRODUCTION

ENGINEERING

BUET


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%%&%"epartment of In'()tria* + $ro'(,tion Enineerin

Chip Formation

Every Machining operaion invo!ve" he #or$aion o# chip"% The nare o#'hich (i##er" #ro$ operaion o operaion) properie" o# 'or* piece $aeria!

an( he cing con(iion% Chip" are #or$e( (e o cing oo!) 'hich i"har(er an( $ore 'earer+re"i"an han he 'or* piece an( he #orce an(po'er o overco$e he re"i"ance o# 'or* $aeria!% The chip i" #or$e( ,yhe (e#or$aion o# he $ea! !ying ahea( o# he cing e(ge ,y a proce""o# "hear% For $ain caegorie" o# chip" are-

"i),ontin(o() Chip)Contin(o() or Ri..on Type Chip)

Contin(o() Chip /(i*t-(p-E'e /UE1

2errate' Chip)


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%%&3"epartment of In'()tria* + $ro'(,tion Enineerin

Type) of Chip)

"i),ontin(o() Chip)- The"e chip" are "$a!!

"eg$en") 'hich a(here !oo"e!y o each oher% Theyare #or$e( 'hen he a$on o# (e#or$aion o 'hichchip" n(ergo i" !i$ie( ,y repeae( #racring% .ar(an( ,ri!e $aeria!" !i*e ,ron/e) ,ra"" an( ca" iron'i!! pro(ce "ch chip"%

Contin(o() or Ri..on Type Chip)- In conino"chip #or$aion) he pre""re o# he 'or* piece ,i!("ni! he $aeria! #ai!" ,y "!ip a!ong he p!ane% Thein"i(e on he chip (i"p!ay" "ep" pro(ce( ,y heiner$ien "!ip) , he o"i(e i" very "$ooh% Iha" i" e!e$en" ,on(e( ogeher in he #or$ o# !ongcoi!" an( i" #or$e( ,y he conino" p!a"ic

(e#or$aion o# $aeria! 'iho #racre ahea( o# hecing e(ge o# he oo! an( i" #o!!o'e( ,y he "$ooh#!o' o# chip p he oo! #ace%


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Contin(o() Chip /(i*t Up E'e- Thi" ype o# chip i"

very "i$i!ar o ha o# conino" ype) 'ih he(i##erence ha i i" no a" "$ooh a" he previo"one% Thi" ype o# chip i" a""ociae( 'ih poor "r#ace#ini"h) , proec" he cing e(ge #ro$ 'ear (e o$ove$en o# chip" an( he acion o# hea ca"ing heincrea"e in oo! !i#e%

2errate' Chip)- The"e chip" are "e$iconino" inhe "en"e ha hey po""e"" a "a'+ooh appearanceha i" pro(ce( ,y a cyc!ica! chip #or$aion o#a!ernaing high "hear "rain #o!!o'e( ,y !o' "hear"rain% Thi" chip i" $o" c!o"e!y a""ociae( 'ih cerain(i##ic!+o+$achine $ea!" "ch a" iani$ a!!oy")nic*e!+,a"e "pera!!oy") an( a"eniic "ain!e"" "ee!"

'hen hey are $achine( a higher cing "pee("%.o'ever) he pheno$enon i" a!"o #on( 'ih $oreco$$on 'or* $ea!" 0e%g%) "ee!"1) 'hen hey are ca high "pee("%


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A,t(a* Chip Form) an' C*a))ifi,ation)

C-type an'6-type.roen ,hip)

2hort he*i,a*.roen ,hip)

Me'i(m he*i,a*

.roen ,hip)

Lon he*i,a*

.roen ,hip)

Lon he*i,a*

(n.roen,hip)

Lon an' )nar*e'(n.roen ,hip)

Desired

Not Desired


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cing con(iion" are he $ain ca"e" #or (i"conino" chip" 2ery !o' or very high cing "pee(

Large (eph o# c

Lo' ra*e ang!e

Lac* o# cing #!i(

2i,raion on he $achine oo!


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Chip Formation in Meta* Ma,hinin

Since he pracica! $achining i" co$p!e3 'e "e orhogona! cing $o(e!o e3p!ain he $echanic"%In hi" $o(e! 'e "e( 'e(ge "hape( oo!% A" he

oo! #orce( ino he $aeria! he chip i" #or$e( ,y "hear (e#or$aion%

Rake angle ()

ToolWorkpiec

e

Chip

Rough

surface

Shiny

surface

Uncut chip

Thickness

a1Sosin !

Chip

Thickness(a")

Shear

#ngle($)

Clearanceangle ()

Shear

plane

Rake

surface

%lank

surface

Neati9e rae

$o)iti9e rae


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%%&:"epartment of In'()tria* + $ro'(,tion Enineerin

"eformation of Un,(t Layer

The pro,!e$ in he "(y o# he $echani"$ o# chip #or$aion i" he(e#or$aion proce"" o# he chip ahea( o# he cing oo!% I i" (i##ic! o

app!y e4aion o# p!a"iciy a" he (e#or$aion" in $ea! cing are very!arge% E3peri$ena! echni4e" have a!'ay" ,een re"ore( o #or ana!y/inghe (e#or$aion proce"" o# chip"% Severa! $eho(" have ,een "e(-

Ta*ing phoograph" o# he "i(e "r#ace o# he chip 'ih a high "pee($ovie ca$era #ie( 'ih $icro"cope%

O,"erving he ri' 'eformation0(irec!y1 on he "i(e "r#ace o# he 'or* piece an(

on he inner "r#ace o# a co$pon( 'or* piece%

E3a$inaion o# #ro/en chip "a$p!e" a*en ,y (rop oo! appara" an(

4ic* "op appara")


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%%&;"epartment of In'()tria* + $ro'(,tion Enineerin

Gri' "eformation Metho')

The ype o# "re""+"ae con(iion" i" eva!ae( ,y $ean" o# an an*e in'e< eo,aina,!e #ro$ Le9y-Lo'e=) theorem)

-[1]-----otan30

e)o(30tan

2e

1e

32e

2e

1e =

+

"e$i+a3e" o# he e!!ip"e a#er (e#or$aion%5r6& r7

ra(i" o# circ!e" $ar*e( on he 'or*piece5ro

800for p(re ,ompre))ion>

300for p(re )hear>

00for p(re ten)ion>

'eformation ,riteria>e?here#

-[2]---o

3

e

2

e

1

eand

or

2r

ln

2

e,

or

1r

ln

1

e =++==

ToolWorkpiece

Chip

ro

r"r1

Sche$aic repre"enaion o#

he ran"!ocaion o# circ!e" inoe!!ip"e" (ring chip #or$aion%


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%%&@0"epartment of In'()tria* + $ro'(,tion Enineerin

Fro$ E4aion 869 an( E4aion 879

]3[

2r1rln

3

2or

2r1rlnotan30

e)otan(30

=

Ca)e-@ For $(re Ten)ion Be>0

-[5]---)(1)4

2

2

2.(1

2

0r2r

and2

1

0r2r

,1or1r

[4]----------)(1or2rand)(1or1r

==+=

=+=

:here)

; 5 cing "rengh

< 5 #riciona! coe##icien5=

"ince ; i" very very "$a!! "o neg!ecing ;7


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%%&@@"epartment of In'()tria* + $ro'(,tion Enineerin

No') #ro$ e4aion 8>9

[6]-----1)(1)(12

0r

22r1r

2

0r2r

0r1r +==

Fro$ E4aion 8?9 an( E4aion 8@9

TensionPureforo0eor,

0tan30e)

0tan(30or,

-[]---1

2r1r

ln

2r1r

.60r

4

2r2

1r

ln

)

2r1r

ln(

3)20r

2r

1r

ln(

0tan30

e)0tan(30

= =

===


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%%&@%"epartment of In'()tria* + $ro'(,tion Enineerin

Ca)e-% For $(re 2hear Be>300

-[!]---1)2

3(1)

2

3(1

0r2r

0r1r

and2

31

0r2r

,2

31

or1r

["]----------)--(1or2rand)(1or1r

++==+=

=++=

Fro$ E4aion 8?9 an( E4aion 89

( )

#$earPureforo30eor,

tan(0)0e)0tan(30or,

[10]-----0

2

r1r

ln

31ln

2

r1r

ln

3

20r

2r1r

ln

0tan30

e)0tan(30

===

===


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%%&@3"epartment of In'()tria* + $ro'(,tion Enineerin

Ca)e-3 For $(re Compre))ion Be>80o

( ) ( ) ]13[---------1-11or

2r

2

or

1r

-[12]---)(1)4

22

2.(1

2

0r1r

and1

0r2r

,2

1

or1r

[11]----------)(1or2rand)(1or1r

+=

+++==+=

=+=

Fro$ E4aion 8?9 an( E4aion 86?9

n%o&'ressioPurefor60eor,

)30tan(tan30e)tan(30or,1

rrln

r

r

r

rrln

tan30

e)tan(30

o

000

2

1

1

2

2

3

0

2

2

1

0

0

=

===

=

17283346 Theory of Metal CuttingTheory of Chip Formation

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Transcript of 17283346 Theory of Metal CuttingTheory of Chip Formation