GEAR DESIGN

STEP 1INPUT:

Blank diameter is 135mm

OPERATION: TURNINGThe Centre Lathe is used to manufacture cylindricalshapes from a range of materials including; steelsand plastics. Many of the components that gotogether to make an engine work have beenmanufactured using lathes. This type of lathe iscontrolled by a person turning the various handleson the top slide and cross slide in order to make aproduct / part.

Power: 3kw Speed: 955 rpm

MACHINE DETAILS: LATHE MACHINE Machine model: Manufactured in

Germany Size : Job swing: 700mm Distance between centres : 3.5

Metres

1. Direct drive 2. Back drive

Feed: Horizontal feed for 1 division is 0.25mm

Transverse motion for 1 division is 0.1mm

Name Plate:

Belt position

A

B

C

D

DIRECTDRIVE 955

515 315

230

BACK DRIVE

199 165

125

99

OUTPUT RESULT:Afterturning operation on lathe the gear blank is

reduces its diameter into required diameter by

giving feed to the gear blank. The blank is reduces

its diameter into 135mm to 125mm. which is outer

diameter of a required spur gear. The output from

lathe machine as follows

Inspection:

The outer diameter of Blank is inspected by using vernier Calliper and is checked whether it is within required tolerance limit.

Digital Vernier calliper

STEP 2

OPERATION: DRILLING

In this step

drilling can be done.

Drilling Process:

Drilling is a process of making hole or

enlarging a hole in an object by forcing a

rotating tool called Drill.

INPUT:

Input for this step is out produced by lathe

machine in our project. The drilling can be done

with 60m of diameter.

Machine specifications:

Range of Spindle speed: 75/1900

rpm

Motors: 2 motors used

Motor 1: Main motor

1.5 HP

Arm elevating motor

0.5 HP

Drilling radius: 440 to 895 mm

Swivel arm L/R side 90 degrees

DRILLING MACHINE

OUTPUT:

The output from the drilling machine as

follows

INSPECTION:

The inspection can be done by Bore gauges, and is checked whether it is within required tolerance limit.

Bore Gauge

STEP 3

INPUT : In this step Gear Hobbing can be done. Input for

this gear hobbing is output of lathe machine that

is 125mm diameter gear blank.

MACHINE SPECIFICATIONS:

Made in: Russia Manufacturer: Komsomolec

Maximum work piece diameter:

1250mm

Maximum Module: 12

Maximum Load: 2000kg

Minimum number of teeth: 20

Motors : total 3 motors used

Motor 1: for cutter bed

3HP

Motor 2: for bed rotation

6HP

Motor 3: for coolant

Material of cutter: Made of High

Speed Steel

Gear hobbing Machine

Gear shaping Machine

Output:After gear hobbing and shaping process the blank

turned into a spur gear as follows

Spur gear

INSPECTION:

Fully automatic measuring cycle with fast

measuring speed. This measuring centre permits

automatic checking of all test items such as

profile, helix and pitch deviations and run out

in one set-up. The measuring cycle is

automatically controlled by microcomputer.

Gear inspection machine

STEP 4

OPERATION: FINISHING OPERATIONS

GEAR GRINDING: Gear grinding is done to impart surface finish to gear teeth

Gear grinding

Grinding machines typically use a wheel that is

made up of one of the manufactured abrasives,

aluminium oxide or silicon carbide.

INPUT:

The input for this grinding is

output from gear shaping or gear hobbing.

Spur gear

MACHINE SPECIFICATIONS:

Machine name: HOFLER H 500 Gear

Grinding Machine

Maximum Diameter of Gear: 500

diameter Mm

Gear Width: 250 mm

Max. Module: 10

Min. Module: 2

Table Diameter: 500 mm

OUTPUT: The output from the gear

grinding is final product which customer requires,

and as per the customer requirements. The final

product is packed and dispatched to the customer.

DESIGN OFGEARSGEARS: As the number of teeth on each

gear is also determined, module and facewidth of

each gear pair is to be determined.

The following requirements must be met in the

design of a gear.

The gear teeth have sufficient strength so

that they will not fail under static load or

dynamic load during normal running conditions.

The gear teeth should have wear

characteristics so that their life is

satisfactory.

The use of space and material should be

economical.

The alignment of gears and deflections of the

shafts must be considered because they effect

on the performance of the gears.

The lubrication of gears must be satisfactory.

Gear tooth strength based on Lewis equation

which is most widely used equation to

calculate tooth bending strength. And the wear

strength of a gear based on Buckingham

equation.

Generally with the help of Lewis equation , module

and face width of a gear are kept as variables in

terms of module and substituting all other terms in

the equation , module is obtained by trail and

error method such that the gear can transmit the

required load.

Equations are available to calculate the static

strength, dynamic load and wear strength of gear

tooth. The static strength of the gear should be

greater than the1.25 to 1.5 times the dynamic

strength based on the type of load and the wear

strength should be greater than the dynamic loads.

If the gear with the calculated module and face

width passes these checks, then it is considered to

be safe.

In any spur or helical pair made of same

material, the smaller gear or the pinion is the

weaker of the two. Hence design should be based on

the pinion

The design Equations for spur gear are as follows

Lewis Equation

Where = tangential load induced on the gear tooth

The values of velocity factor as given below

In the above expression, v is the pitch line velocity in m/s

b = face width of a gear in mm

m = module in mm

y = Lewis factor based on form of teeth

Static load or Endurance strength:

WS = Static load that a gear tooth can be endure

Flexural endurance limit of the material

For safety, against tooth breakage, the static

tooth load (Ws) should be greater than the dynamic

load (WD). Buckingham suggests the following

relationship between Ws and WD

For steel, the Flexural endurance limit ( ) may be obtained by using the following relation:

Dynamic loads:

= Dynamic load on teeth acting while working

v = pitch line velocity in m/s

C = deformation factor N/mm

It depends upon the error in action between teeth,

the class of cut of the gears, the tooth from and

the material of gears, the following table shows

the values of deformation factor ( C ) for checking

the dynamic load on gears.

Wear Tooth Load:

The maximum load that gear teeth

can carry, without premature of wear, depends upon

the radii of curvature of tooth profiles and the

elasticity and surface fatigue limits of the

materials. The maximum or the limiting load

satisfactory wear of the gear teeth, is obtained by

using the following Buckingham equation.

The load stress factor depends upon the maximum

fatigue limit of compressive stress, the pressure

angle and the modulus of elasticity of material of

gears. According to the Buckingham , the load

stress factor is given by the following relation:

Surface endurance limit values of

different materials

For agear to transmit power safely without bending

failure and with satisfactory life, the following

conditions must be satisfied.

≥ , to avoid tooth breakage

≥ , to have a satisfactory life

Design of spur and helical gears are very similar

and helical gears are stronger than spur gears due

to the fact that the teeth are inclined more than

on tooth are in contact at any given instant.

SPUR GEAR DESIGN

The design calculations for the selected spur gear

system are given below

Input data is

Power to be transmitted P = 50 KW

Hardness of material = 320 BHN

Flexural Endurance strength ( ) = 560 M Pa

Allowable bending stress ( ) =

350 M Pa

Surface Endurance Limit ( ) = 826

M Pa

Velocity ratio is 2

Centre distance L = 600 mm

Pinion rpm = 400 r.p.m

Centre distance L = (Dp/2 + DG/2 )

600 = ( Dp/2 + 2Dp/2 )

1200 = 3Dp

400 = Dp

Therefore DG = 800

The gears are made of same material hence,

therefore pinion is weaker

Pitch line velocity of the pinion

v = (π Dp*Np)/60

= ( π*0.4*400)/60

= 30.15

Since v greater than 12 m/s , the velocity factor

is

Cv=6/(6+30.15)

= 0.166

We know that number of teeth on pinion

Tooth form factor for pinion

Yp = 0.1750.0021 m

Assuming the service load factor is 1

We know that design tangential tooth

load,

WT = (50000/30.15)*1

=1658.37 N

We know that tangential tooth load (WT )

1658.37 =

= ( 350*0.166 )*9m*π*m*(0.1750.0021 m )

= 287.33 3.4480

Solving the above equation

m =2.44 say 3mm

Facewidth:b = 9*m

=27 mm

Number of teeth in gear:

Number of teeth on pinion

Tp =Dp/ m

= 400/ 3

=133.33 say 134Number of teeth on gear TG = DG/ m = 800/3 = 267.66 say 268

Checking the gears for Dynamic and wear load: We know that dynamic load ,

On substituting respective values intothe equation we get

WD = 1658.37+3478.84

= 5137.21 N

Tooth factor:

yP= 0.1750.0021 m = 0.175 –0.0021*3

= 0.1687

The static load or endurance strength of tooth

= 560*27*π*3*0.1687

= 24028 N

Ratio factor

= ( 2*2 )/(2+1)

= 1.33

Maximum or limiting load factor

= 400*27*1.33*1.47

=21115.08 N

ConclusionSince both WS and WW are greater than WD, therefore design is safe.