CSVTU Code: ME 10611

B.Tech. (Sixth Semester) Examination (April-May) 2010

Subject: Machine Design ll.Branch : Mechanical Engineering

Time: Four Hours Max. Marks: 80

Min. Pass Marks: 28

NOTE: (i) Aftempt "r)

r,r" questions.Assume suitabte data if required.

(ii) Use of PSG Design Data book is permifted.

.Y A helical compression spring is made of cold drawn steel wires of Grade 2 and is/ axially loaded by a force of 450 N. The spring index is 5 and the number of active coils is 6. '

The permissible shear stress for the spring wire is 3?t "

the ultimate tensile strength.

Design the spring and specify the dimensions.

(16)

,e Design a spur gear drive to transmit 5 kW at 1440 rpm. Speed reduction is 3.5, with,/' other specifications as follows:

(i) Material for pinion is C 45 steel and for gear is 1SNi 2 Cr 1 Mo15 steel.

(ii) The gears are ground gears used in gear boxes with sliding gears.

(iii) Both matbrials are surface hardened with Rockwell l.rardness in range of 40 to 55.

(16)

.gl A pair-ofXeliealgearsloJransmitSS kW at 1500 rpm. The spbed reduction is 5 and.-rz'-

the helix angle is 15 degrees. The gear drive is occasionally subjected to pronounced

dynamic loads, Design the gear drive selecting suitable material having life of 10,000 hours.

(16)

Q4 A pair of bevel gears has a velocity ratio of 2'.1. The pitch circle diameter of the pinion

is 80 mm at the large end of the tooth. 5 kW power is supplied to the pinion that rotates at

800 rpm. The face width is 40 mm and the pressure angle is 200. The gear is supported on

two bearings on either side at equal distance of 100 mm from the plane containing large end

of tooth. Find the tangential, radial and axial components of the resultant tooth force acting

on the gear. Find also bearing reactions assuming the bearing near the meeting point of

center lines of both pinion and gear to take thrust also.

(16)

a5 (af The radial load acting on a ball bearing is 2500 N for the first five revolutions and

reduces to 1500 N for the next ten revolutions. The load variation then repeats itself. The

expected life of the bearing is 20 million revolutions. Determine the dynamic load carrying

capacity of the bearing.

(08)

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05 (b) A system involves four identical ball bearings each subjected to a radial load of

2500 N. The reliability of the system, i.e. one out of four bearings failing during the lifetime of

five million revolutions, is 82%. Determine the dynamic load carrying Capacity of the bearing,

so as to select it from the manufacturer's catalogue based on g0% reliability.

(08)

QO A fulljournal bearing operates with following data:

Length of bearing = 0.15 m, Diameter of journal = 0.10 m, Radial load on bearing = 22.7 kN

Speed of journal = 250 rev/min, Radialclearance = 0.045 mm.

It is desired to limit the minimum oil film thickness to 0.025 mm. determine a suitable value

for the viscosity of the lubricant and the power loss due to friction.

(16)

Q7 A single plate clutch consists of only one pair of contacting surfaces. lt is used for an

engine that develops a maximum torque o'f 120 N-m. Assume a factor of safety of 1.5 to

account for slippage at full engine torque. The permissible intensity of pressure is 350 kPa

and the coefficient of friction is 0.35. Calculate the inner and outer diameters of the friction

lining assuming

(i) uniform wear theory, and

(ii) uniform pressure theory.

(16)

Q8 Design a flat leather belt drive to transmit 10 kW at 1440 rprn. The speed of driven

shaft is 480 rpm. The center distance is two times the diameter of larger pulley. The belt

should operate at a velocity of 20 m/s approximately, the stresses in the belt should not

exceed 0.95 gm/cubic cm and the coefficient of friction is 0.35. The thickness of belt is 5

mm. determine

(i) the diameter of pulleys

(ii) the length and width of the belt and

(iii) the belt tension.

(16)

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B.Tedh'{Sixth Sdb'ester} Exanrii#'*ion .(April-May} 2009-,' . S*bJeet:,FtLnefouneiDmffi.{f

B raneh : Mechani,eal ffingilicerfrngTinne FourHgfiqs"

NorE; r4nempt aryfive questiow" ,4,ssume suitabtre datg t{yequiredUlqe of PSG Dcsign data bookis permfttefl.

Ql (af Design a helical spring for a spring loaded safety valve from the following data: Valvediameter = 65 mm, Maximum pressure when the valve blo\trs off freely = 0.25 Nlmmr, Valve lift

'1: when pressure rises fiom 0.7 te 0.75 N/mmz = 3 Fnmo Maximum permissible stress tn th;matenal of the spring = 500 N/mmz, spring index = 6, Modulus of rigidity of the spring material =1x105 N/mm2.

(081(b) A locomotive spring has an oterall'length of 1.5 m and sustains a load of gb kN at its

centre. The spring has 3 full length leaves and 15 graduated leaves with a central band af fiAmm wide" All leaves are to be str:essed to 430 N/rnnnz when fuiiy loaded. The ratio of spring depth$$Wg":i;ftn$;Qe w;gq !?rl,thbkpess sJ leave$*,Taftp.F +, ?. 1 .o, r o5 N/mmz, . .:-.

-

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W 'rDesign spur gear drive to transm[ 1.5 Lw "t lunry* rro* an eiechie motor to an aircompresscr running at,720 rpm with other speeffieations as follows: A

(i) Material for both. pinion and gear: east.lron Grade 35, Heat Treated with Brinell" Hardness of 230.

(ii) Type of gear transmission being speed redueer, gears being non€round with life ofreohours.

f {t6}

#. Besign a pair of helieal geaffl to trqnsmit gg kw at 1500 rprn of the pinion" The speed/ 'redftstion is 5 and the helix angle is 15CI. Ttle rnaterial of gears is case hardened steel 40 Ni 2 ern Mo 28. The gearing type is spen with nonground geare of Rsckweil Hardness 50, The effective

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Men hflarks:90

Min" Pass:lWnrtes: Zg

lib of frear material ean be taken as 10,000 krours"

PTE

"4{ Design a bevelgeardrive to transmit 1CI kW at 1440 rpm" Gear natio is s and nnatertsl f@

n**tp pioiun and u**, L e-4G sr.eel with Roel$ryetl hadness ot a*0" life being 12,000 hsurs" ltre

gears are used in speeei redueers housed io ,ore, beanngs witir value of ioad eonrentration factor

as 1"2.

{{6}

pf Design a 3600 journal bearirg for a entritugbl punnp to tfre folloruing speeifieations;

ll.5 kN"X"m"t"r of the joumal = ZS mm, Speed ofjoumal ='1f40 rpm, toad on eaehlournal ='Use MeKecs equation for detemination of coefficieht of frie'tion" &sume e = 0"001D. Also find oil

flow thrsugh bearing for seleeted bearing pressure and minimym frlm,thickness for minimum

frietion" :. j : tj.

'.{{ yI Aball bearing is operating on a work qycle consisting of threq parts * a,rad"ra!!93d,of

AOOO N at 1440 rpnn for one quaf,er eyele, a radial load of 500.0 N at 720 rpm Tor one half cyqle,

and a radial load of 2500 N at 1440 rpm for the remaining eyele" The expeeted life of the beadng

is 10,000 hours. ealculate the dynamie load caffig eapacity gJthe,bearing" :'' '' j'i

,{08}

6 e system invoives four" identieal balf bearings each'su$eded'to a radiaib'ad of 2500N.

The reliabiliff of the system, i.e. oRe out of four bearings failing during the lffetimabr fi-vetffiillion

revoiuiiorra, is g2 e/o. Betermine the dyfibmic load ea;rying'' paeity of the bearing so as to seleet

it ftom the manufaeture/s eatalogue based sn 90 o/o reliabill$.

igatI.

8? Detemnine the torque transmitted by eluteh using"

(D Uniform Pressure theor1r ' .

!ii) . Uniformu€artheory ,. ,i . ,, '1"'

, (16)

eg The folloruing data is given for an open-type V-bett drive: diameters of elriving and drlven

, pulleyg = 200 mm & 600 nrm respeetively, groore angle for sheaves * &40, mass of bclt = 0r5

kgm, maxinrum pennissible tension in belt * 500 lrt;'eoeffieient sf ffic{ion = 0"2, contad anglet

and speed of smaller"pulley * trS70 and 1440 rpm, powerto he transnniffied * {0 kW"

Horu many V-betts should be used, assunning eaeh'bett takes ib propodional part of the

load? )

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$"Teeh (stx& semesfer) Exnminatf,on (Aprf,t-frray) z00s eodes &x8CI8611

. i SablW Mn*ine Desf;gru ru-'a :.

Etmehe Ms€hrnlcfll Enginesring

Timc; ThreeHonrs n'fax"hfiarkre S0

nfiia" Pf,sr FIrr*s:2f,NCITE: Attempt al! qaestiow. Asswtc suitable darc if reqaircd

Use af PSG Design dota book is permitted

/4"ffi .Attempt any two parts . ..;..r

(a) Derive fomoula for fastor of safety for fatigue toading of springs" (CIs)

\V Find the wire diameter ad mean coil diameter for a closcd+sil helicai spring of a boiler safe.V

Ydve. Take &e initial eompmEs$ion of the spring as 25 mm ad th lift is limited tc l0 mm. Tb blow offsteam presslre is 2 tvtra and tbc vdve diameter is 50 mm. Take shear stness as 3S0 Mpa and ryring indexas 6"

(e) Mt: the stess, force and defleetion relmionship for multi-leaf springs.

".(a} w"nregry,$ry,p.......@-..gfoi co, m-B!96 g*!g,.g{*rp'ruggps,,,,..

r.:,.,. : .'.,,.(08J

. ' (b) A pair ofr4$!qs,.p,'g,.sess pyt lf.{i+4!{itg$*-#-.gj 10gg.dol.p.,. T, 9 trr€h damereEef rbesmaller gear is 160 mm. If thc qanryflIge4fir-is,3 top,.gf,lsul4e: Glnqnnberof.,@ foreachgear,(ii) adaenqrm, (iii) rvhole depdr, (iv) clearanee, (v) outside diametcrs, (vr) nqot diamerers, (vii) dedendum,(viii) base gir*l* diamete$ and (rx) cheek for interference. , (08)

/oR'

"Ftgn e spur gear drive to hansnnit 1.5 kw at 1440

eompr€ssorrunning at 720 rpm"

(08)

(08)

rpm ftom an eleo{rie motsr to an air

(16)

h frgure shorne a 0"?5 kW eleehie motor nms at 30 revls inotroekwisc direstion" as viewed fr,om the posf,tive x-mis" Keyed tCI fumotor shaf is an i8-too& hsliea! pinion having a nomnal pmdssur€ angle

ofZff, a helix anglCI of 3ff, and a nomal mnodule of 2"0 mm" Tbe hand offu btix is shoqnn^ shon'in&oee dimsiond lin€ diagrm tbe fffiading sn the prnion md trG bctring reaetions fic A ad B. The thnls is tobCItakmatA"

# trH-; l; .,.:

/:,"futWa bevel gcar drive te bansmit 4 kW Sp€€d i$do = 4, drivrng sirafr speed ='2ZS p. The

drive is non-reversible" Assume tife of 26,000 hmm;

fA4/ A shaft is supported between two beanngs 0.5 m,apart. It emies a pultry wcighing 1200N at

.:udA"ptu. The'te,nsions in the belts in ttre horizontal direc'tions hre ZSOO.W and 1250 N on dght and slaek

side respeetively. Select the propm bearing for shaft diametm sf 50 mm; There is an axidlqry$ of 2000 N"

tife ofbearing should be 6000 hours at 300 rpno" .

It is required to find rhe load carrying papaEr"fy,,E$g#yeod:mwiejournd,pw.rfuigthiggl€og&6f

jotrnal as 50 mm. Take absolute viseosrty * 20 x.l0€u}.g$,o,Js6al ,6peed =.l.4ag.fu: &@.=rt, rfldml

elearanee = 0.05 mm and minimum fibn thiekness =,o"utrt *-" Also deter4tnp pgwer,llost rn &icdon md

theoiltemperature,ifu&oleoftheheatsanbedi$stpdd.;:.; :.; r ::,..:; ,.: r.r,,

^S ( , :,lii,,t,-,i;*ij: ji.:jieii.}AbJi;ff"3,",,,i:!'.;i,*,. iiii _.*, :_. ,{lO

,/\ F A multiple disk elutcb, steel on b,roaze, N to tranmit,4;kv.,.:.,$,,?50 rsv/1mie The rnne r-adius of r\./: eons*"is.4$*or.esd the oubr radirrs nt dn*T:i$*fG,iqt{

coeffieient of ftietion 0.10. The average altowabie pt ssrqe is 3s0 kli/ez m u*.(r) Howmaay total dislis ofsteel,andbrorizerare r,eduiffi'?.,.' . ;:

:istheaveragepr€ssllrc? " .'' i

"":1i:'''; .-,'' .''

(1u) Wlrt aXial fOrCC iS f-eqUifed ? r*-''rii"'1':'::'lirt ';i:i j.+'l:'' ' ' ': r'';i:r 'r ''r :''

(19 What is the astud mardmrm pressp,? ' i

ORI '. ,;ii.'-r : '

An open leather flatb€lt is required to tranmit z0 kTr fiom a 300 ffir

(1q

:.' f .

nmning at 1440

.rpm to a 750 mm putley" Take eoefifieienrt of frietion for &iver puiley =,0.4, eoefficient of fuetion f,or

&iven pulley = O3, e€'nt€r distanee * 2 m, densiry of,bett rytqld = g?Q,kq/qql, maxsam peruisstifesftess in thc beJt : 1.? ffi. Defiermine the width of rhe b€lt fo; a thiehess- rf iO nn*,

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iI

eode: t)76t)23 NI

B,E,(Sixth Semester) Examination Apr-hday 2007Subjeeft Maehine Design ff

Branchr Mechanrical Engineering

Timcs Three Hours Max Marksl 100foIin Fnss lVlanks:35

o

Note. Attempt all questions. Assume suitnbledata.if required..Drawneat sketehes. Use PSG design data book is permitted"

The following data is given for a pair of spur gears with 200 full depth

involute teeth -Number of teeth on pinion:24

Number of teeth on gear = 56

Speed of pinion = 1200 rpm

Module = 3 mm

Service factor : 1.5

Face widtti = 30 mm

(i) bpam strength '. :i .

(ii) velociry factor, and

(iii) rated power that the gefprs ean transmit without bending failure, ifthe factor of safeff is 1,"5"

i

(a) 5 KW powbr at 720 rpm is supplied to pinion having helical teeth. The

normal module is 5 mm and the normal pressure angle is 200. The pinion has

right hand teeth while the gear has left hand teeth" The helix angle is 300"

The pinion rotates in eloekwise direetion when seen from the right hand

side" Detennine the eomponents of the tooth-force and draw a free-body

diagram showing the forces acting orighe pinion and the gear"

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Using the velocity factor to'aeeougt tbr the d1'namie load, calculate -

P"T.0.

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Q.3

20

20eQ.4

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ryfu,

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,rk6 Derive expression for fastor of safety from fatigue'diagram for spnng design SS- JCI

es given in data book'

,{6 It is required .to desiga a-.he}icaltotsibo,-s$rrng-for a window-=shade-- Tne - - ---:--*

spring is made of patented anetr oold-drawn steel wire of Grade 4. 't'he yield

strength sf the materit'is 607s of the uttimate tensile strengtir, and the factor

of safety iy2" From space considerations, the mean eoil diameter is kept as

K**. Tlie maximum bending moment aeting on the spring is 250 N-hm.

The modulus of clastieity'of the sprini-rnaterial is20V x 103 N/mrnz. The

stiffness of the spring should be 3 N-mmlrad. Detennine the wire diameter

and the pqnlber of aetive eoils"

i)W