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8/2/2019 Sample Report - Greeked Text
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Sample report.
Some items of text have been obscured
The Queen's University of Belfast
Mechanical & Manufacturing Engineering
Stage 2 - Gearbox Design Project
2010/2011
David Thornhill
Summary
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Contents Page No.
1 Design overview ..................................................................................................................... 1
1.1 Introduction ...................................................................................................................... 2
1.2 Xoxxo xoxoo .................................................................................................................... 3
1.3 Xxoxoxoo ......................................................................................................................... 5
1.4 Oxoxxo xoxoo.................................................................................................................. 5
1.5 Xooxoxooxo oxoxxox ..................................................................................................... 6
1.6 Solid modelling ................................................................................................................ 7
1.7 Conclusions ..................................................................................................................... 7
Appendix 1 - Design specification ............................................................................................ 8
Appendix 2 - Design spreadsheets........................................................................................ 10
A2.1 Gear stress analysis - Stage 1................................................................................. 11
A2.2 Gear stress analysis - Stage 2................................................................................. 13
A2.3 Gear forces ................................................................................................................. 15
A2.4 Shaft and key size selection ..................................................................................... 16
A2.5 Input shaft loads and bearing selection .................................................................. 17
A2.6 Midshaft loads and bearing selection...................................................................... 18
A2.7 Output shaft loads and bearing selection............................................................... 19
A2.8 Midshaft and output shaft gearwheel press fits ..................................................... 20
Appendix 3 - Marking ............................................................................................................... 21
List of figures
Figure 1: Xxxoxoo oxxx oo xxxooox....................................................................................... 2
Figure 2: Xoxxo xoxoo .............................................................................................................. 3
Figure 3: Xxoxoxoo ................................................................................................................... 4
Figure 4: Oxoxxo xoxoo ........................................................................................................... 5
Figure 5: Xxxooox oxoxxo ........................................................................................................ 6
Figure 6: Xxooxxo xxxoxoo oo xxxo xxxx ooooxxo xxoxx xoo ooxxo xxo oooxx ............ 7
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Page 1 of 23
1 Design overview
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Page 2 of 23
1.1 Introduction
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1.3 Xxoxoxoo
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Figure 6: Xxooxxo xxxoxoo oo xxxo xxxx ooooxxo xxoxx xoo ooxxo xxo oooxx
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1.6 Solid modelling
To the best of my knowledge there were no features of the design that I was unable toachieve because of the limitations of the solid modelling software.
1.7 Conclusions
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Appendix 1 - Design specification
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Gearbox design specification
Senior Designer and Project Engineer: David Thornhill
Introduction:
Although a specific application for the gearbox has yet to be determined it is likely to find
application in the aerospace industry. As such, it is important that the design is optimised to
provide the required power capacity at the minimum weight. It may be assumed that the
installed attitude of the gearbox will remain constant.
Specification:
1. Gearbox to use two gear stages
2. Speed ratio between input and output shafts: 12:1
3. Speed of input shaft: 3000 rev/min4. Power capacity (at input shaft): 14 kW
5. The input shaft and the intermediate shaft are to be vertically above the output shaft.
6. The output shaft is to allow drive to be taken from either side of the gearbox.
7. Direction of input shaft rotation viewed on end is clockwise.
8. Lubrication is to be by oil splash.
9. Gears to have a minimum life of 20000 hrs
10. Minimum gear stress safety factor: 1.2
11. Gears to be of helical form ( 20 - 30 helix angle) to minimise noise, vibration andharshness (NVH)
12. Gears are to be sufficiently wide that the helix causes at least one tooth to be in fullmesh at all times on each gear pair.
13. Individual gear pair ratios to make use of hunting teeth.
14. Bearings should have a life of 10000 hrs with 90% reliability. If, however, it can beproven that the bearings become unacceptably large a reduced service life may bespecified that will allow smaller bearings to be utilised.
15. The input shaft will be subject to a maximum radial load (N) of 10 x the input torque(Nm). This will act vertically downwards on the shaft at a distance of 25 mm from the
outermost surface of the gearbox case.
16. The output shaft is not subjected to any external radial loading.
17. The gearbox is to provide adequate mounting feet to support itself and any reactionsdue to the torque and forces acting on the input and output shafts.
18. The input and output shafts are to be equipped with keyways of proportions adequateto transmit the required torque.
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Appendix 2 - Design spreadsheets
The following spreadsheets have been revised from their originally submitted and markedform to reflect changes to the design that were necessary during the solid modelling stage of
the project.
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A2.1 Gear stress analysis - Stage 1
Senior designer David Thornhill
Geometry Comment
Module (mm) 1.50
Facewidth (mm) 20.00
Helix angle (deg) 20.00
No of teeth 19 84
Gear ratio 4.42
Centre distance (mm) 82.21
Reference diameter (mm) 30.33 134.09
Pitch diameter (mm) 30.33 134.09
Tip diameter (mm) 33.33 137.09
Root diameter (mm) 26.58 130.34
Quality Comment
Grade (1-12) 5 5
Surface finish - Flank (micro m Ra) 0.80 0.80
Surface finish - Root (micro m Ra) 3.20 3.20
Material
Material Steel Steel
Quality (A, B or C) B B
UTS (MN/m^2) 2300 2300UTS Core (MN/m^2) 1000 1000
Surface hardness (HV) 700 700
Surface hardening Case hardened
Case depth (mm) 0.30 0.30
Post hardening operation Very light grind
Operation
Gear speed (rev/min) 3000.0 678.6
Required life (hours) 25000
Application factor, KA 1
Kinematic viscosity of lubricant at 40 C (mm^2/s) 115
Power (kW) 14
Notes:
1. Typically the module size of the second stage will be the next size up from the first stage.
Generally, if the permitted stress levels are much higher than the actual stress levels the
module size should be reduced.
2. If the gear face widths are too small the module size should be reduced. Try to keep in
the range 20 30.
3. Face width must be greater than: ( )m/tan , where m is the module and is the helix
angle.
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Contact stress Comment
Speed and lubrication factor, ZL*Zv 0.931
Roughness factor, ZR 0.945
Material quality factor, ZM 0.900 0.900
Work hardening factor, ZW 1.000 1.000Size Factor, ZX 1.000
Life factor, ZN 1.000 1.000
Minimum demand safety factor 1.2 1.2
Casedepth factor, Zc 1.000 1.000
Disc/gear correction factor, ZG 0.838 0.899
Endurance limit for contact stress for discs (MN/m^2) 2130 2130
Endurance limit for contact stress for gears (MN/m^2) 1783.993 1915.021
Permissible contact stress (MN/m^2) 1177.68 1264.176
Zone factor, ZH 2.371
Elasticity factor, ZE 189
Contact ratio factor, Z epsilon 0.804
Dynamic factor, Kv 1.025
Transverse load factor, KH alpha 1.150
Face load factor, KH beta 1.433
Nominal tangential force acting on teeth at ref circle (N) 2939
Actual calculated contact stress (MN/m^2) 1141.739 1141.739
Root bending stress Comment
Life factor, YN 1.0 1.0
Surface condition factor, YR 0.905 0.905
Size factor, YX 1.0 1.0Material quality factor, YM 0.9 0.9
Sensitivity factor, Y delta 1.027 1.033
Minimum demand safety factor 1.2 1.2
Residual stress due to post heat treatment finish (MN/m^2) -400 -400
Basic endurance limit of polished specimen under areversing bending load (MN/m^2)
560 560
Permissible bending stress (MN/m^2) 750.8 755.7
Tooth form factor, YF 1.544 1.320
Stress correction factor, YS 1.837 2.112
Helix angle factor, Y beta 0.833
Transverse load factor, KF alpha 1.150
Face load factor, KF beta 1.350
Actual bending stress (MN/m^2) 368.6187 362.2568
Sub surface bending stress Comment
Residual stress due to post heat treatment finish (MN/m^2) 240 240
Permissible bending stress (MN/m^2) 380 380
OverEng Over Eng
Actual bending stress (MN/m^2) 120.376 102.9011
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A2.2 Gear stress analysis - Stage 2
Senior designer David Thornhill
Geometry Comment
Module (mm) 2.50Facewidth (mm) 24.00
Helix angle (deg) 20.00
No of teeth 21 57
Gear ratio 2.71
Centre distance (mm) 103.76
Reference diameter (mm) 55.87 151.65
Pitch diameter (mm) 55.87 151.65
Tip diameter (mm) 60.87 156.65
Root diameter (mm) 49.62 145.40
Quality Comment
Grade (1-12) 5 5
Surface finish - Flank (micro m Ra) 0.80 0.80
Surface finish - Root (micro m Ra) 3.20 3.20
Material
Material Steel Steel
Quality (A, B or C) B B
UTS (MN/m^2) 2300 2300
UTS Core (MN/m^2) 1000 1000
Surface hardness (HV) 700 700Surface hardening Case hardened
Case depth (mm) 0.40 0.40
Post hardening operation Very light grind
Operation
Gear speed (rev/min) 678.6 250.0
Required life (hours) 25000
Application factor, KA 1
Kinematic viscosity of lubricant at 40 C (mm^2/s) 115
Power (kW) 14
Notes:
1. Typically the module size of the second stage will be the next size up from the first stage.
Generally, if the permitted stress levels are much higher than the actual stress levels the
module size should be reduced.
2. If the gear face widths are too small the module size should be reduced. Try to keep in
the range 20 30.
3. Face width must be greater than: ( )m/tan , where m is the module and is the helixangle.
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Contact stress Comment
Speed and lubrication factor, ZL*Zv 0.904
Roughness factor, ZR 0.945
Material quality factor, ZM 0.900 0.900
Work hardening factor, ZW 1.000 1.000
Size Factor, ZX 1.000
Life factor, ZN 1.000 1.000Minimum demand safety factor 1.2 1.2
Casedepth factor, Zc 1.000 1.000
Disc/gear correction factor, ZG 0.871 0.902
Endurance limit for contact stress for discs (MN/m^2) 2130 2130
Endurance limit for contact stress for gears (MN/m^2) 1854.393 1920.23
Permissible contact stress (MN/m^2) 1188.587 1230.785
Zone factor, ZH 2.371
Elasticity factor, ZE 189
Contact ratio factor, Z epsilon 0.807
Dynamic factor, Kv 1.008
Transverse load factor, KH alpha 1.150
Face load factor, KH beta 1.240
Nominal tangential force acting on teeth at ref circle (N) 7053
Actual calculated contact stress (MN/m^2) 1164.107 1164.107
Root bending stress Comment
Life factor, YN 1.0 1.0
Surface condition factor, YR 0.905 0.905
Size factor, YX 1.0 1.0
Material quality factor, YM 0.9 0.9
Sensitivity factor, Y delta 1.027 1.032Minimum demand safety factor 1.2 1.2
Residual stress due to post heat treatment finish (MN/m^2) -400 -400
Basic endurance limit of polished specimen under areversing bending load (MN/m^2)
560 560
Permissible bending stress (MN/m^2) 751.2 754.6
Tooth form factor, YF 1.523 1.355
Stress correction factor, YS 1.855 2.046
Helix angle factor, Y beta 0.833
Transverse load factor, KF alpha 1.150
Face load factor, KF beta 1.182
Actual bending stress (MN/m^2) 379.1003 371.9306
Sub surface bending stress Comment
Residual stress due to post heat treatment finish (MN/m^2) 240 240
Permissible bending stress (MN/m^2) 380 380 Over Eng
Actual bending stress (MN/m^2) 138.9686 123.6383
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A2.3 Gear forces
Specification
12
3000
14
Gears
Gear Module Helix Number Ref Dia Speed Torque
Angle of teeth mm rev/min N.m
1 1.50 20.00 19 30.33 3000.00 44.56
2 1.50 20.00 84 134.09 678.57 197.02
3 2.50 20.00 21 55.87 678.57 197.02
4 2.50 20.00 57 151.65 250.00 534.76
Gears tooth forcesGear Tangential Separating Axial Acting to
N N N L or R
1 2938.7 1138.2 1069.6 R
2 2938.7 1138.2 1069.6 L
3 7052.8 2731.7 2567.0 R
4 7052.8 2731.7 2567.0 L
Dr D. Thornhill
Power (kW)
Gear ratio
Input speed (rev/min)
Senior designer
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Page 16 of 23
A2.4 Shaft and key size selection
Input shaft size
44.56
205.00
10.35
6.00
6.00
3.50
18.00
Input shaft key size
137.00
275.00
18.00
6.006.00
6.02
6.00
18.00
Output shaft size
534.76
205.00
23.68
10.008.00
5.00
34.00
Output shaft key size
137.00
275.00
34.00
10.00
8.00
22.96
28.60
32.00
26
117
Minimum key length by compression, (mm)
Minimum key length by shear, (mm)
Minimum key length by compression, (mm)
Key allowable shear stress, ( )
Key height, h (mm)
Key allowable compressive stress, ( )
Shaft outside diameter at keyway, d (mm)
Torque (N.m)
Shaft allowable shear stress, ( )
Shaft diameter under key, (mm)
Shaft outside diameter, d (mm)
Key width, b (mm)Key height, h (mm)
Shaft and key size
Key height, h (mm)
Key depth in shaft, (mm)
Shaft outside diameter at keyway, d (mm)
Key width, b (mm)
Midshaft size, d (mm)
Torque (N.m)
Shaft allowable shear stress, ( )
Shaft diameter under key, (mm)
Key allowable shear stress, ( )
Fill in the cells highlighted in beige with your own values or values from tables, as appropriate,
and enter appropriate formulas into the remaining cells to determine the shaft sizes and key
lenths.
Standard key length (mm)
Key width, b (mm)Key height, h (mm)
Key depth in shaft, (mm)
Standard key length (mm)
Minimum key length by shear, (mm)
Shaft outside diameter, d (mm)
Key width, b (mm)
Key allowable compressive stress, ( )
a
ukd
1t
a
a
sl
cl
2mm/N
2mm/N2mm/N
a
ukd
1t
a
a
sl
cl
2mm/N
2mm/N2mm/N
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Page 17 of 23
A2.5 Input shaft loads and bearing selection
Variables
a 19 mm Gear width 24
b 74.25 mm Left gap 3
c 51 mm Right gap 40
Reactions
R1 R2
(N) (N)
Vertical 123.2 -815.8
Horizontal 2186.7 752.0
Combined 2190.1 1109.5
Bearings
Left (A) Right (B)
Part No. 32005X 32205B
C 27000 35800
a 11 16
T 15 19.25
e 0.43 0.57
Y 1.4 1.05
Fr/Y 1564.4 1056.7
Test
Ax Force 782.2 1851.8
Fa/Fr 0.357 1.669
P 2190.1 2388.2 117L10 ( ) 4328.1 8306.0
Hours 24045.2 46144.4
% 240.5 461.4
New C ? 20752 22628
-253.9
Fill in the cells highlighted in beige with your
own values and enter appropriate formulas
into the remaining cells to determine the
bearing reactions and bearing lives
Input shaft loads and bearing selection
b
a
R1v
R2v
r1
Fs1
Fa1
c
10xTI
b
a
R 1h R2h
Ft1
c
610
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Page 18 of 23
A2.6 Midshaft loads and bearing selection
Variables
a 19.25 mm Gear width 20
b 45.25 mm Pinion width 32
c 70.5 mm Left gap 3
Right gap 3
Reactions
R3 R4 Rightward
(N) (N) (N)
Vertical 1883.3 -3476.8
Horizontal -4662.3 -5329.2 1497.4179
Combined 5028.3 6363.1
Bearings
Left (A) Right (B)
Part No. 32206 32206
C 50100 50100
a 15 15
T 21.25 21.25
e 0.37 0.37
Y 1.6 1.6
Fr/Y 3142.7 3976.9
Test
Ax Force 1571.3 3068.8
Fa/Fr 0.313 0.482
P 5028.3 7455.2L10 ( ) 2128.4 572.7 117
Hours 52277.6 14066.1
% 522.8 140.7
New C ? 30503 45226
417.1
Fill in the cells highlighted in beige with your
own values and enter appropriate formulas
into the remaining cells to determine the
bearing reactions and bearing lives
Midshaft loads and bearing selection
b
c
R 3v R4v
r2
Fs2
Fa3
aF
s3
r3
Fa2
b
c
R3h
R4h
Ft2
aFt3
610
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A2.7 Output shaft loads and bearing selection
Output shaft loads and bearing selection
b
R5v R6v
r4
Fs4
Fa4
a
b
R5h R6h
Ft4
a
Variables
a 19 mm Gear width 24
b 58.0 mm Gap 0
Bearing gap 20
Reactions
R5 R6
(N) (N)
Vertical 6982.4 -4250.7
Horizontal 9363.2 -2310.4
Combined 11680.0 4838.0
Bearings
Left (B) Right (A)
Part No. 33109 33109
C 84200.00 84200.00
a 19.00 19.00
T 26.00 26.00
e 0.37 0.37
Y 1.60 1.60
Fr/Y 7300.0 3023.8
TestAx Force 3650.0 6217.0
Fa/Fr 0.313 1.285
P 11680.0 11882.4L10 ( ) 723.7 683.4 117
Hours 48246.7 45561.5
% 482.5 455.6
New C ? 52514 53424
-2138.1
Fill in the cells highlighted in beige with your
own values and enter appropriate formulas into
the remaining cells to determine the bearing
reactions and bearing lives
610
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Page 20 of 23
A2.8 Midshaft and output shaft gearwheel press fits
Midshaft
130.34
31.00
20.00
205.00
200.00
188.69
211.31
-188.69
0.060
31.025
31.000
31.06031.044
0.019
59.27
894.7
4.54
Output Shaft
145.40
46.00
24.00
205.00
200.00
179.98
220.02
-179.98
0.090
46.025
46.000
46.090
46.074
0.049
98.26
3919.03
7.328566 117
Contact pressure based on min interference ( )
Torque capacity of joint (N.m)
Safety factor
Shaft
diameter
Upper limit of size (mm)
Lower limit of size (mm)
Minimum interference on diameter, (mm)
Radial stress, ( )
Maximum interference on diameter, (mm)
Hole in
gearwheel
Upper limit of size (mm)
Lower limit of size (mm)
Young' modulus for gear ( )
Allowable shear stress for gear ( )
Contact pressure based on shear stress ( )
Hoop stress, ( )
Gear tooth root diameter, D (mm)
Shaft nominal diameter at press fit, d (mm)
Length of press fit, l (mm)
Minimum interference on diameter, (mm)
Contact pressure based on min interference ( )
Torque capacity of joint (N.m)
Safety factor
Upper limit of size (mm)Lower limit of size (mm)
Hole in
gearwheel
Shaftdiameter
Upper limit of size (mm)
Lower limit of size (mm)
Midshaft and output shaft gear wheel press fits
Contact pressure based on shear stress ( )
Hoop stress, ( )
Radial stress, ( )
Maximum interference on diameter, (mm)
Gear tooth root diameter, D (mm)
Shaft nominal diameter at press fit, d (mm)
Young' modulus for gear ( )
Allowable shear stress for gear ( )
Length of press fit, l (mm)
2mm/N2mm/N
2mm/Nh
r
MAX
MIN
2mm/N
2mm/N2mm/N
2mm/N2mm/Nr
MAX
MIN
2mm/N
2mm/kN
2mm/kN
2mm/N
h
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Page 21 of 23
Appendix 3 - Marking
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Report (10%) Poor Adequate Good V. Good Excellent Exceptional
0 - 39 40 - 49 50 - 59 60 - 69 70 - 84 85 - 100
Overall Presentation
Quality of Figures
Quality of Discussion
TOTAL
Gearcase Drawing (15%)Mark Comment
Are all views correct and relevant (0 - 3%)
Datums properly defined (0 - 4%)
Geometric tolerances (0 - 2%)
Dims to correct datums (0 2%)
All dimensions available (0 2%)
Are notes free from errors (0 2%)
TOTAL
Penalty marks (-7% Max)Penalty Comment
Improper submission of solid model (0 - 4%)
Incorrect binding of report (0 - 3%)
Incorrect folding or trimming of drawing (0 - 2%)
Missing marking sheets (0 - 2%)
TOTAL
Late WorkDays Late Comment
Solid Model
Report
Gearcase Drawing
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Solid Model (50%) Description Penalty
Gross errors
Significant errors
Minor errors
Under definedsketches
Poor modelling
Incorrectly definedstandard parts
Draft
Radii
Chamfers
TOTAL
Special Bonus