Mechanical Engineering Design

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(No Transcript)
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Mechanical Engineering Design
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Contents

• Preface 4
• What is a gearbox?5
• Project description..7
• Bulky characteristics of gearbox..8
• Gear design.9
• Shaft design34
• Deflection consideration37
• Bearing selection41
• Computer programming54
• Acknowledgments..55
• References..56

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Preface

• The present work is a class project of mechanical
  engineering design
• on Samands gearbox. The quad did as much as
  possible in order to
• analyze ,collect, calculate and present the
  results. At first we have a
• historical vision on gearbox then all the parts
  of gearboxs
• evaluations (some with more details) will be
  considered. we have
• utilized some CAD soft wares like
  ANSYS,solidworks , catia Mdesign and the
  programming is MATLAB language.
• We are really grateful of Dr.vakili on behalf of
  the recommendations and hope to satisfy him about
  the process.

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? What is a gearbox

• Gears are about as old as any of
• the machinery of mankind. The oldest machine
• is the potter's wheel. At first time over 3000
• years ago primitive gears first meshed
• with each other and transmitted rotary motion .
• Water wheels were used to convert energy of
• moving water into energy that would power
• machines. Wooden gears connected water
• wheels to machines that would grind wheat
• and hammer metals.

• A transmission or gear box provides speed
• and torque conversion and from a rotating
• power source to another device using gear
• ratios. In British English the term
• TRANSMISSION refers to the whole drive
• train, including gearbox, clutch, prop shaft,(
• for rear wheel drive), differential and final
• drive shafts. The most common use is in
• motor vehicals,where the transmission
• adapts the out put of the internal combustion

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• Often, a transmission will have
• multiple gear ratios (or simply
• "gears"), with the ability to switch
• between them as speed varies.
• This switching may be done
• manually (by the operator), or
• automatically. Directional (forward
• and reverse) control may also be
• provided. Single-ratio
• transmissions also exist, which
• simply change the speed and torque (and sometimes
  
• direction) of motor output .

Gearboxes have found use in a wide variety of
differentoften stationaryapplications, such as
wind turbines. Transmissions are also used in
agricultural, industrial, construction, mining
and automotive equipment. In addition to ordinary
transmission equipped with gears, such equipment
makes extensive use of the hydrostatic drive and
electrical adjustable-speed drives.
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Project description

• It is desired to design a gearbox To get this
  we first anaylzed
• the forces and power generated in the internal
  combustion engine
• then according to the inpute data like the
  maximum torque and maximum power gears designed
  Then by considering the shasfts distans and gears
  diameters the critical gear mated during the
  engaging identified Then all diameters of shafts
  were found out It is important to note that we
  used some steps through the shafts inorder to
  reduce the material used in manufacturing
• At last all the bearings were selected for the
  most critical
• condition and all the data and informations were
  wrote besides .the figures

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Bulky characteristics of gearbox
39.15Kg Total weight
420mm length
240mm width
310mm height
0.0312m3 Occupied volume
195 Approximate cost
150(mm) Normal distance of shafts
360mm Upper shaft length
410mm Lower shaft length
40mm Distance of gear 5,4
5mm Distance of gear 4,3
20mm Distance of gear 3,2
5mm Distance of gear 2,REV
60mm Distance of gear REV,1
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Gear design

• There are some important notes to be informed.
  First we calculated the power generated ,from
  some principle physics and fluid mechanics.
  During the engaging of the gears to the higher
  speeds, the power increases and the torque
  reduces. For the rear gear we assumed the
  conditions as well as 1stt gear,inorder to have
  the worst situation. the assumption for the
  overload factor was according to the speed of the
  shaft. when we have low speeds it should be less
  than 1.5 and when the speed increases ,the
  unbalanced forces increases and the overload
  factor shouldnt be less than 2.The gear strength
  for live assumed 108 cycles the reliability
  was set 99.Temperture factor was not considered.
  The surface condition factor was almost 1 because
  of our gear materials. All the gears are from
  steel but different hard nesses.

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Gear1(pinion)
2.5 Mn
70mm D
24 N
40mm F
St,grade2 ,550HB Material
3000rpm W
64.5hp H
13128N Wtnd
20 n
30
1 Ko
1.2 SF
1.2 SH
8 Qv
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(more details)
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Gear1(gear)
2.5 Mn
230mm D
80 N
40mm F
St,grade2 ,550HB Material
913rpm W
64.5hp H
13128N Wtnd
20 n
30
1 Ko
1.4 SF
1.3 SH
8 Qv
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(more details)
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Rear gear (pinion)
2.5 Mn
70mm D
28 N
40mm F
St,grade2 Carburized hardened Material
3000rpm W
64.5hp H
13128N Wtnd
20 n
0
1.25 Ko
1.5 SF
1.2 SH
8 Qv
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(more details)
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Rear gear (gear)
2.5 Mn
230mm D
92 N
40mm F
St,grade2 Carburized hardened Material
913rpm W
64.5hp H
13128N Wtnd
20 n
0
1.25 Ko
1.02 SF
1.1 SH
8 Qv
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(More details)
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2nd gear (pinion)
4 Mn
105mm D
22 N
40mm F
St,grade2 Carburized hardened Material
3700rpm W
70hp H
7700N Wtnd
20 n
30
1.5 Ko
2 SF
1.2 SH
8 Qv
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(more details)
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2nd gear (gear)
4 Mn
195mm D
42 N
40mm F
St,grade2 Carburized hardened Material
2000rpm W
70hp H
7700N Wtnd
20 n
30
1.5 Ko
2 SF
1.2 SH
8 Qv
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(More details)
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3rd gear (pinion)
4 Mn
130mm D
30 N
30mm F
St,grade2 450HB Material
4500rpm W
80hp H
5845N Wtnd
20 n
30
1.5 Ko
2 SF
1.12 SH
9 Qv
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(more details)
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3rd gear (gear)
4 Mn
170mm D
40 N
30mm F
St,grade2 450HB Material
3440rpm W
80hp H
5845N Wtnd
20 n
30
1.5 Ko
2 SF
1.12 SH
9 Qv
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(more details)
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4th gear (pinion)
4 Mn
152mm D
33 N
30mm F
St,grade1 300HB Material
5300rpm W
90hp H
4775N Wtnd
20 n
30
2 Ko
1.1 SF
2 SH
9 Qv
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(More details)
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4th gear (gear)
4 Mn
148mm D
32 N
30mm F
St,grade1 300HB Material
5443rpm W
90hp H
4775N Wtnd
20 n
30
2 Ko
1.1 SF
2 SH
9 Qv
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(More details)
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5th gear (pinion)
4 Mn
172mm D
38 N
20mm F
St,grade1 350HB Material
6000rpm W
100hp H
4140N Wtnd
20 n
30
2 Ko
1.1 SF
2.5 SH
9-10 Qv
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(More details)
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5th gear (gear)
4 Mn
128mm D
28 N
20mm F
St,grade1 350HB Material
8062rpm W
100hp H
4140N Wtnd
20 n
30
2.5 Ko
1.1 SF
2.5 SH
9-10 Qv
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(More details)
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Shaft design

• Now it is the time to design the shafts. The most
  important note is the gears weight. For the upper
  shaft, we assumed concentrated weight at the
  center of the gears but at the lower shaft
  because of their large size, we assumed uniform
  distributed force. The other note is the steps.
  During the calculation, we saw that there are
  some parts that can be manufactured with less
  diameters. saw we considered some steps and used
  3mm fillet radius. The fatigue failure was one of
  the important factor. this is stated after
  evaluating the other parameters like critical
  frequency and defelction.the SODERBERG was the
  relation for the fatigue failure. The deflection
  would result in larger diameters, so we used one
  more bearing in each shaft to reduce the
  deflection.
• The calculations resulted in the critical
  condition when engaging the rear or the 1st gear.
  so we examined the gear 4 in order to reject it
  as the bad condition then we solved the problem
  on the base of rear and 1st gear.

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Upper shaft
Critical situation is when rear gear is engaged.
36mm 50mm 45mm Diameters from left to right
1030HR 1030HR 1030HR Material
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Lower shaft
Critical situation is when rear gear is engaged
50mm 47mm 34mm Diameters from left to right
1045 CD 1045 CD 1045 CD Material
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Deflection considerations(ANSYS)
Other gears just vanished.
Modeling
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Showing the fillets of the steps.
Uniform load distribution of the gear.
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Stress distribution. (before middle bearing)
Stress distribution. (after middle bearing)
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Stress distribution. (after middle bearing)
Stress distribution. (after middle bearing)
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Bearing selection

• We were supposed to select 4 bearings ,two for
  the upper shaft and two for the lower shaft. But
  when evaluating the deflections we saw that it is
  worth to try the 3rd bearing for each shaft and
  reduce the undesirable deflection which can cause
  force increased during the engaging. So we did
  it and
• According to the critical forces, we selected the
  suitable bearing from SKF online bearing
  selection for a long life.Ofcourse in bearing
  selection, its diameters ,mass and cost were
  considered.

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Upper shaft (right side)
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Upper shaft (right side)
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Upper shaft (Left side)
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Upper shaft (Left side)
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Upper shaft (middle)
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Upper shaft (middle)
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Lower shaft( right side)
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Lower shaft( right side)
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Lower shaft( left side)
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Lower shaft( left side)
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Lower shaft (middle)
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Lower shaft (middle)
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Computer programming

• In order to computerize the evaluations ,we wrote
  the program which gets some input data like
  m,Np,Ng,Wt,speed and some others and predicts the
  coefficient of safety for pitting and
  bending.Ofcourse we are really grateful of
  Mr.milanchiyan for his prior program which we
  have extended it .There is an animation which
  shows the operation.

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Acknowledgment

• At first we really thanks GOD which provided the
  conditions in order to work on the project as
  much as possible. Then we are really grateful of
  our wise master,Dr.vakili on behalf of the
  recommendations. We really thanks from TAKARAN
  CO(ISACO bureau in TEHARAN) , our dear engineer
  ,Mr.Ghorbani and our classmate Mr.milanchiyan.We
  hope to develop our performance in future
  works.enshalah.

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References

• 1.Budynas,Nisbett,shigleys mechanical
  engineering design,6th,7th,8th edition,Mc graw
  Hill,

2 .???? ???? ????????????? ? ????? ???? ??? ?????
ANSYS
3.????? ?? ANSYS????? ????????????? ??????? ????
??????
4.www.SKF.COM
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The Group