Sample Report - Greeked Text

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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1 Design overview


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Page 2 of 23

1.1 Introduction

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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



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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


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



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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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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


19/25

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


20/25

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


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


21/25

Page 19 of 23

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


own values and enter appropriate formulas into

the remaining cells to determine the bearing

reactions and bearing lives

610


22/25

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



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



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


23/25

Page 21 of 23

Appendix 3 - Marking


24/25

Page 22 of 23

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


25/25

Solid Model (50%) Description Penalty

Gross errors

Significant errors

Minor errors

Under definedsketches

Poor modelling

Incorrectly definedstandard parts

Draft

Radii

Chamfers

TOTAL

Special Bonus

Sample Report - Greeked Text

Documents

Transcript of Sample Report - Greeked Text