Measurements unit-3

8/13/2019 Measurements unit-3

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MEASUREMENTS11 ES 102

L T P

3 0 2

M. NAGESHASSISTANT PROFESSOR

Measurement of

LINEAR DISPLAEMENT


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General objec!"e

3.0 To #n$ersan$ he %eas#re%en o& '!near (!s)lace%en #s!ng $!&&eren *)es o& %echan!cal an$ o)!cal $e"!ces

S)ec!&!c objec!"es

3.1 Inro$#c!on o (!s)lace%en %eas#re%en

3.2 (!%ens!onal %eas#re%en

3.2.1 +ern!er ,al!)ers

3.2.2 Scre- Ga#ge

3.3 Ga#ge blocs

3. Iner&ero%eer O)!cal %eho$

3. Pne#%a!c $!s)lace%en ga#ge


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INTR!DUTI!N T! DISPLAEMENT MEASUREMENT

(!s)lace%en

I !s he shores $!sance be-een -o )o!ns4 -!h a $e&!ne$ $!rec!on.

+ecor 5#an!*.

A "er* !%)oran )ara%eer o cons!$er !n !n$#sr* !n "ar!o#s a))l!ca!ons.

E6 he $!s)lace%en o& 127% be-een -o ho rollers !n )a)er !n$#sr* o

$e&!ne he h!cness o& )a)er.

One o& he %os !%)oran %echan!cal 5#an!* ha aes a "!al role!n !n$#sr*


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8 San$ar$ &or $!s)lace%en !s "en#t$an$ #n! !s metre.

1. (!sance be-een -o %ars o& a ro$ e) !n Par%s.

2. 19:0 cr*)on;: so %an* -a"elenghs < 1 %ere

3. 'aes san$ar$ !s 19;2 = "eloc!* o& he l!gh !n "ac##% &or $#ra!on

o& 1 / 299>92; secon$s


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T*)es o& !nsr#%ens

Mechan!cal *)e

+ern!er ,al!)ers Scre- ga#ge M!cro%eer

Scales Ga#ge ?locs

Pne#%a!c *)e

(!s)lace%en ga#ge Fla))er=No@@le se #)

Elecr!cal *)e

Poen!o%eers '+(T /R+(T

Elecro%agne!c $e"!ces ,a)ac!!"e )r!nc!)les

Elecron!c *)e

Enco$ers P!e@o $e"!ces

Accelero%eers

O)!cal *)e Iner&ero%er* Iner&erence


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DIMENSI!NAL MEASUREMENTS

'o- "al#e$ $!sance %eas#re%ens are calle$ $!%ens!onal %eas#re%en.

s#all* less han 1 %%.

&ern%er 'a"%(ers) m%'rometers are bes e6a%)le o %eas#re he

$!%ens!on o& a g!"en s)ec!%en acc#rael*.

&ERNIER ALIPERS*

The +ern!er cal!)ers g!"e a $!rec rea$!ng o& he $!sance %eas#re$ o h!gh

acc#rac*.

These cal!)ers co%)r!se a cal!brae$ scale -!h a &!6e$ ja-4 an$ anoherja-4 -!h a )o!ner4 ha sl!$es along he scale.

&ern%er 'a"%(ers 'an measure %nterna" +%mens%ons ,us%n# t$e u((ermost -as/

eterna" +%mens%ons , us%n# t$e "oer -as/.


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1. !uts%+e -as #se$ o %eas#re e6ernal $!a%eer or -!$h o& an objec

2. Ins%+e -as #se$ o %eas#re !nernal $!a%eer o& an objec

3. De(t$ (roe #se$ o %eas#re $e)hs o& an objec or a hole

. Ma%n s'a"e scale %are$ e"er* %%

. Ma%n s'a"e scale %are$ !n !nches an$ &rac!ons

4. &ern%er s'a"eg!"es !ner)olae$ %eas#re%ens o 0.1 %% or beer

5. &ern%er s'a"eg!"es !ner)olae$ %eas#re%ens !n &rac!ons o& an !nch

6. Reta%ner #se$ o bloc %o"able )ar o allo- he eas* rans&err!ng o& a %eas#re%en


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Scale *)e

(!al *)e (!g!al


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MIR!METER ,SRE7 GAUGE/*

M%'rometer s're #au#e)!s a $e"!ce !ncor)ora!ng a cal!brae$

scre- #se$ -!$el* &or )rec!se %eas#re%en o& s%all $!sances

!n %echan!cal eng!neer!ng an$ %ach!n!ng.

M!cro%eers #se he )r!nc!)le o& a scre- o a%)l!&* s%all $!sances

ha are oo s%all o %eas#re $!recl* !no large roa!ons o& he

scre- ha are b!g eno#gh o rea$ &ro% a scale.

Bors #n$er -o )r!nc!)les4

The a%o#n o& roa!on o& a scre- can be $!recl* relae$ o a cera!na%o#n o& a6!al %o"e%en.

A g!"en a%o#n o& a6!al %o"e%en -!ll be amplified!n he res#l!ng

c!rc#%&eren!al %o"e%en.


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rame* The ,=sha)e$ bo$* ha hol$s he an"!l an$ barrel !n consan rela!on o each oher.

n9%"* The sh!n* )ar ha he s)!n$le %o"es o-ar$4 an$ ha he sa%)le ress aga!ns.

"ee9e : arre" : sto';* The sa!onar* ro#n$ )ar -!h he l!near scale on !. So%e!%es +ern!er %ar!ngs.

o'; nut : "o';


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Three %os co%%on *)es o& %!cro%eerD

The!r na%es are base$ on he!r a))l!ca!on

1. !uts%+e m%'rometer* T*)!call* #se$ o %eas#re -!res4 s)heres4

sha&s an$ blocs.

2. Ins%+e m%'rometer se$ o %eas#re he $!a%eer o& holes.

3. De(t$ m%'rometer* Meas#res $e)hs o& slos an$ se)s.

S(e'%a"%=e+ t>(es

n!"ersal %!cro%eer ?la$e %!cro%eer T#be %!cro%eer

?ench %!cro%eer '!%! %!cro%eer ?all %!cro%eer


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Objec $!a%eer "al#e< Ma!n scale (!al scale 6 ',


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GAUGE ?L!@S

Recang#lar seel blocs %ach!ne$ an$ la))e$ )ol!sh a s#r&ace #n!l

s%ooh an$ har$ene$ !ncreas!ng !n har$ness o& a %eal.

The!r s#r&aces are so h!ghl* )ol!she$ an$ r#e ha -hen r#bbe$ o"er

each oher4 hese s!c ogeher.

Ga#ge blocs are #se$ &or chec!ng he!gh ga#ges4 %!cro%eers4

+ern!er cal!)ers an$ oher )rec!s!on e5#!)%en.


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D%fferent sets


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Measurement of +%ameter

Measurement of $e%#$t

?locs are no sace$ b* s!%)l*

res!ng he% one on o) o& anoher.

The* %#s be -r#ng ogeher !n

s#ch a -a* as o el!%!nae all b#

he h!nnes o!l &!l% be-een he%.

Th!s o!l &!l%4 !nc!$enall*4 !s an!negral )ar o& he bloc !sel&D !

canno be co%)leel* el!%!nae$4

s!nce ! -as )resen e"en a

%an#&ac#re. Pro)erl* -r#ng

blocs %are$l* res!s se)ara!on

beca#se he a$hes!on be-een he

s#r&ace !s abo# 30 !%es ha $#e

o a%os)her!c )ress#re.


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?locs %a* be asse%ble$ b* WRINGING-o or %ore ogeher o

%ae #) g!"en $!%ens!on.

E6= suppose that a dimensional standard of 14.715 mm is desired.

The procedure for arriving at a suitable combination might be determined by

successive subtraction, as indicated below.

?"o';s use+

Desired Dimension = 14.715

Ten-thousandths place = 1.5 1.5

!emainder = 1".71

#undredths $lace = 1.%1 1.%1

!emainder = 1%.5

Tenths $lace = %.5 %.5

!emainder = 1.

Two wear bloc&s = 4. '%. each( 4.

!emainder = ).

*nits $lace = ). ).

!emainder = . Check. 14.715

Pro'ess of us%n# t$e #au#e "o';s for measur%n# +%mens%ons


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Meas#re%en o& angle

b* gage blocs

se o& ga#ge blocs !n !n$#sr*


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Eam("e*In he %eas#re%en o& he!gh o& a6!s conrol nob

Toal he!gh o& nob< ?ase he!gh s#% o& he !n$!"!$#al ga#ge bloc

"al#es #se$


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INTER8ER!METER ,MIHELS!NS/

Interferometr>re&ers o a &a%!l* o& echn!5#es !n -h!ch -a"es4

#s#all* elecro%agne!c4 are s#)er!%)ose$ !n or$er o e6rac !n&or%a!on

abo# he -a"es.

Iner&ero%eers are -!$el* #se$ !n sc!ence an$ !n$#sr* &or he

%eas#re%en o& s%all $!s)lace%ens4 re&rac!"e !n$e6 changes4 s#r&ace

!rreg#lar!!es ec.

(!&&erence be-een he -o -a"es-a"es ha are !n )hase -!ll

#n$ergo consr#c!"e !ner&erence -h!le -a"es ha are o# o& )hase

-!ll #n$ergo $esr#c!"e !ner&erence.

PRINIPLE


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F!g#re sho-s he

consr#c!onal &ea#res o& a

M!chelson !ner&ero%eer4

-h!ch can be #se$ o

%eas#re he %o!on o& an

objec.

The %!rror a M !s hal&

re&lec!ng an$ hal&

rans%!!ng.


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Monochro%a!c l!gh &ro% he so#rce !s coll!%ae$ b* he

lens ono he s)l!er )lae -h!ch !s hal& re&lec!ng an$ hal& rans%!!ng

o-ar$s he %!rror an$ -or )!ece.

?oh bea%s are re&lece$ bac an$ reco%b!ne$ a he s)l!er )lae an$

hen rans%!e$ o he screen.

Fr!nges %a* a))ear on he screen res#l!ng &ro% $!&&erences !n he

o)!cal )ah lenghs o& he -o bea%s.

I& he !nsr#%en !s )ro)erl* consr#ce$4 hese $!&&erences -!ll ar!se &ro%

$!%ens!onal "ar!a!ons o& he -or )!ece.

The !ner&ero%eer !s )r!%ar!l* #se$ &or cal!bra!on o& gage blocs.


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Press#r!@e$ a!r !s &e$ hro#gh he or!&!ce an$ !s ejece$ &ro% he no@@le

o-ar$s he &la))er.

The &la))er !s )os!!one$ aga!ns he no@@le o)en!ng an$ he no@@le

bac )ress#re conrolle$ b* he no@@le=&la))er $!sance.

As he &la))er a))roaches he no@@le he resr!c!on o no@@le !s !ncreases

hereb* !ncreases he bac )ress#re P0.

I& &la))er co%)leel* closes he no@@le bac )ress#re e5#al o !nle a!r

)ress#re.

I& &la))er a-a* &ro% no@@le a large $!s)lace%en hen bac )ress#re

!s e5#al o a%os)her!c "al#e.

The change !n bac )ress#re !s )ro)or!onal o $!s)lace%en.

PNEMATI, (ISP'A,EMENT GAGE


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Measurements unit-3