AIN SHAMS UNIVERSITYFAGULTY OF ENGINEERING

DESIGN & PRODUCTION ENGINEERING DEPARTMENT Aryird Yeor Mecltanical, power Section1'' Semester, 2008-2009 Maximum mark = (1 Time: 3 Hours

Machine Construction and

-@ach!ne

Equlprnento Students nroy -o Constructional drawings shoulcl be fully dimensioned wittt machining

,".:!.::.:':.:::.:'.:::::{I::,:.'::.,:r..':!:,.1,::.,.r...,.,rrr.......,.......,The layout of a two stage reduction unit is shown in the given sketch. 'lhefirst stage is through a helical intemal meshing spur gears. The second stageis a V-belt drive.

The particulars of the drive are as follou-s:Motor speed 1800 qpmGear Center distance 300 mmGear/Pinion teethPressure angleBelt speed ratioBelt size

180/30200

2:l25x16 mm

Belt center distance 900 mmNumber of belts 5Smaller pullci' dram. 300 mi::,Tooth width 80 mm

You are asked to:

1- Specify the materials, class of workrnanship and hardness of the gears tohave the same Power capacity (+20% overload) as that carried by thebelt drive in the second stage. [!e Marksl

2- Calcdate the bearing capacity for the ouput shaft (B) due to belt powercapacity if the expected life is 20000 hr. t30 Marksl

3- Check the strength of the 80 mm diameter output shaft [B] if its materialis St 50. 115 Marksl

4- Drar.v a constructional drawing for the gear unit assernbly. [40 Marksl

Exsminer: Prof./ Heshsm Aly Senbel WA

Mochine Design-fanuary -2009- Third Yeor Mechanical, Power Sy4ro" tplgttlQ

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M achine D esign-January -2 0 09- Third Year Mechanical, Power Section [Page: 3/4J

Useful Data. Pt:ob.b.m.K K=Kr.Kr/Kr.K1. Modified form factor: 0.48 - 12.85 I Zrl. Deformation factor:0't 1 e I lllBr+ 1/E*]

. Lubrication factor : 1.25

. Velocity factor: 3/(3+v)

. Sen,ice factor : 1.8

. Speecl factor :2 vi [1 + u]

. E; : (21x10a MPa) ----- Ecr: (12 xl0a MPa)

o P.n:o.n'kr'b'mn P* : 1.25 Po: k* . kn . b .Drl

"os' Y

" P.: P, tan CI, sec /t Pu : Pltan Y

A:ka.b.cos2y+Pt. p _o* Acos/^d ^t . i*gllJE

V

. Coefficient of friction befweenbelts and pulley :0'2

. - Bearing axial factor (y) : 1

Module series in mm Start 1 4 7

Step 0.25 0.5 1

bno 4 v t6

: Probable elrorModule Commercial Accurate Precision

Up to 4.5 50 25 12

6 60 30 15

7 70 35 t7

8 80 4A 20

t2 100 50 25

25 120 60 30

Permissible (maximum)enor, [Pm]

0: i80o t 2u,

-- 180o + 2 sin'I LD-d / 2c)

max '20 25 30 35 40 50

1 2 3 4 5 6 7 8 9 10 L/. t)e 125 100 9s 86 63 55 50 44 39 38 26 25 t4 13 L2 l1 10 I

. V-Belts Design Eqyations:

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M achin e D esign-J an aary - 2 0 0 9-

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Third Year Mechanicat, Power Section [Page: 4,

Angular contact factor (KrI

Transmitted Power Per Belt. [Kwl

Strength of some materials(Uttimate, Yield Stress and

r,i,

:r'

BrrN), MPal

a'

Minimum Pulley diameter (d*). mm:

b 5 6 8 t0 13 t7 20 22 25 32 40 50

h 3 4 5 6 8 ll t2.5 l4 16 20 25 3L

d- 22 32 45 63 90 t25 180 212 250 355 500 , 710

Beltwidth, mm

5 6 8 10 13 t7 20 ?2 25 32 40 5(

,.D

ooo,>q)

2 0.01 8 0.037 0.074 0.1 40 0.272 05 15 0.736 0-810 1.104 r.766 2.723 4.4

4 0.035 0.074 0.1 40 0:272 0.545 0.957 1.398 1.693 2.208 3.459 5.446 E

6 0.050 0.1t0 0.206 0.405 0.810 1.398 2.061 2.502 3238 5.152 8.096 13.

8 0.063 0.1 40 0.265 0.530 030 1.840 2.723 3:38 4.195 6.771 0.30 16.

10 0.074 0.162 0.3 r6 0.640 251 2.282 3.312 3.901 5.078 8.1 70 2.51 20.

12 0.081- 0.1 84 0.353 0.736 _472 2-650 3.827 4-490 5.888 9.42t 4.72 z).

t4 0.081 0.191 0.383 0.810 .6r9 2.944 4.269 s-152 6.624 10.60 6.r9 26.

16 0.081 0.199 0.412 0.883 766 3.165 4.637 5.520 7.213 I1.56 7.66 28

18 0.074 0.191 0.412 0.883 914 3.386 4.93r 5.888 7.654 t2.22 9.r4 30.

20 0.059 0.177 0.397 0.957 987 3.s33 5.078 6-035 7.875. 12.59 9.87 31

22 0.037 0.1 55 0.361 0.883 .987 3.s33 < I<'.) 6 IOQ 8-07:7,. t2.,77 9.87 32

24 0.1l0 0.309 0.810 .914 3.459 s.005 6-035 7.581 12.51 9.14

26 0.059 0.221 0.736 .840 3.312 4.784 s.741 7.434 11.85 8.40 JU

28 0.132 0.66 .693 3.018 4.416 5226 6.845 10.89 6.93

30 .472 3.650 3.754 4-563 s.888 9.568 14.72,2J

Materialin MPa

Type UTS Yeld BHN

GG18 150-220 1 700

GG26 230-280 2100

GG30 250-300 2204

G538 380 '180

G56O 600 360

st42 420-500 220 1 300

st60 600-700 300 1 800

st70 700-850 340 2200

c15 500-650 300 1400

c22 500-600 300 1 550

c35 600-720 370 1700

c60 750-900 490 240018CrNi8 650-1400 1 900-600(

37MnSi5 600-1 050 1700-300(

Load stress factoi MPa

Material BHN Kw

St/St 1500 / 1500 0.292500 / 1500 0.562000 / 2000 0.6

2500 I 2500 0.953000 / 2500 1.14

3500 / 2500 1.38

4000 / 3000 1.8/ nn ,2Enn+UUU , J.,r.uV: - 2.26000 / 4500 3.6

st/cl6000 / 6000 5.5

1500 / 1800 0.4

2000 / 1800 0.82500 /1600 1.5

cl/cl 1800 / 1800 1.6

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