Examiner: Profc' Hesham Aly Sonbol

T: True F: Falls

Question 2: [6 Marks]

A bevel gear assembly as shown in Figure (2) working under the following conditions:Bearings A and B: 60x130x31x34 (C=61KN), Bearing C: 70x170x5l (C=132KN). The thrustarising from the straight bevel gear of diameter 80 mm and rotating at 1200 rpm is 6KN.Specifications of threaded end of shaft: rv148x4! core diameter -= 41.] rnm, height of nut =-3Rmm.

Gear Center distance 200 mmPressure angle 20°Belt center distance 400 111mTooth width 20 111m

Motor output speed 1800 rpmGear/Pinion teeth 150/50Belt speed ratio 3: 1Smaller pulley diarn 100 rnmCoefficient of friction 0.2

You arc asked to:1- rind the size and number of the V-belts based on the motor capacity [6 Marks]2- Find the helical gears material based 011 static strength only [6 Marks]3- Calculate the bearing capacity for the output shaft for the gear unit if the expected life

is 20000 hr (6 Marks]4- Check the strength of the 40 mm diameter output gear unit shaft if its material is St 42 . [6 Marks]5- Draw a constructional drawing for the gear unit assembly [10 Marks]

Question 1: [105 Marks]The attached sketch, Figure (1), shows the layout of a Helical Spur Gear Reducerwhich it has to be installed up-side for a special application in factory. Power issupplied to the unit through an electric motor of 3Kw and a V-bclt drive. The outputof the unit is finally delivered to a conveyor through a system of flat belt.

The particulars of the drive are as follows:

• Students may assume any missing data.lOt Constructional drawings should he fully dimensioned with machining

symbols and classes of fits clearly indicated.

~=--==:=:.--;=:=====:=:============.--===============-~-==.-==-:-=.~--=-==--=:.;._-==-=:.~Mechanical Engineering Design II MANF 353

The exam consists of Five questions in Four pages----------------------------------------

AIN SHAMS UNIVERSITYFACULTY OF ENGINEERINGNew Programs - [2011-2012]MANUFACTURING ENGINEERING PROGRAMFinal Exam - Maximum marks [40] - Time allowed: 3 hr

r---'I 2/4 IL__ ._.1

[ Figure_2j

ear

'. Flat belt Pulley

. Output Shaft//

"'-. T C··, op eilinq

f//////////////I J .......

elt , ~ ~ ----~1; V ~r , ........r-v

<, .

~-~.~~,11 )] r G

\ Pinion

It<,

+ Motor---- --

I \I

1/ / / / / / / / / / / / / / A

Figure 1

Mech anical Engineering Design II ilt!ANF 353 - January -2011-/Page: 214/

ema:-; : Permissible (maximum)error, [urn]Iv~-I- 2-'3T41516'7'8'9TTO'l2T'5120T2530'3514050~~,·:.j·'25±ioot 95 j86~3 ~5150144 !~~blJ.~_!_!j 13 ! 12rr{i 10~9 ~

o V-Belts Design Equations:0= 1800 ± :2 sin" [D-d 12C]

F, ~ltO-.- = e[2

• Coefficient of friction between belts and pulley = 0.2• Bearing axial factor (y) = 1

A =KI . b - cos2 Y + PI

• Pell = (Yen • k, . b . m• pw = 1.25 PJ = k., . k, . b . D, / COS2 7• Pr = PI tan o. sec r• P a -= P t tan re p =p +_ ~ cos, _

d t 1+0_1~)Av

ECI= (12 xlO" MPa)

$ PI = Gb· b . m . K K = K". K, ; K, .K,• Modified form factor = O.4R - r2.85 !Zd• Deformation factor = 150 'N/mm• Lubrication factor = 1.25• Velocity factor = 3i(3+v)• Service factor = 1.2• Speed factor =:: 2 u / [1 + u I., Est= (21 xl O'~MPa) -----

Useful Data

Mechanical Engineering Design II 111AiVF 353 - January -2011- [Page: 3/4/===:=:====================~==:=====::======:;:=====================:======~=::=====:=============~~~====~

Stl St 1500 1 15002500/1500----2000/2000---2500/2500---_.3000/2500------3500/2500----4000/3000

--+.._:4~000I 35006000/4500--6000/6000150011800'.-- --- ---2000/1800----.-.-2500/1600-.--

CII CI 1800/1800

Material in MPaType UTS Yield BHNGG18 150-220 ---- 1700GGi6 230-280 2100

_----

GG30-- ~50-300~ - -~200 __J;S38 - -.-- --.

380 180--- -36JL '-.-----GS60 600--.--

~O-500 1,220-::0..1)1300-'-St42_---,-~00-700 300- 1800'-St60._---~00-8S0- ~O ---.-

St70 2200C1S-- 1-500-650 300 1400rc22 -'- 500-600 300 ~550-..--- --- '-370 - 1----'-C35 600-720 1700.-- - f---.-.-._ 1-._:- ---C60 750-900 490 24001sCrNi8 - 1-650-1400 1900-6000---- ---- -- 1--.-.-.-37MnSi5 600-1050 1700-3000

Strength of some materials(Ultimate, Yield Stress and BHN), "!\1Pa

Transmittcd Power per Belt, IKw"

~~-~--~-~------~---~-~--_--I 0, + 180-+ 17Q__!J..60~+-:1SO_I ~Q_J 13Q_j _!_?~_!_!_~Q_I.l OO~E_Q_4- 80 ).. 70 Il~ul_O_lO.9! 1_Q·9).L0.9~ O.821_Q:__8~..2JUQ}!_I_Q·7_j Lil·68_LO.O_)_l0.581

Nlinimum Pullcy diameter (dm). mm:

'·b1S'6l._S:]O-1 13T17T20-1 22J_-25 132'140' 50-11h_~.-I·-3-1-4 ~ 5 -t- 6 f 8 T II TI2.5_l 14_1 16 I 20 i 25 I 32~~d", S221_]~,_4S~_61_ L9JL_L!25[_]_8Q_j 212 _L250_1 355_L sOQ_J 7 IQ_J

Angular contact factor (Kit

Useful Data

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