汽车差速器中英文对照外文翻译文献.docx

汽车差速器中英文对照外文翻译文献.docx

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汽车差速器中英文对照外文翻译文献

汽车差速器中英文对照外文翻译文献

Failure

analysis

of

an

automobile

differential

pinion

shaftAbstract

Differential

is

used

to

decrease

the

speed

and

to

provide

moment

increase

for

transmitting

the

movement

coming

from

the

engine

to

the

wheels

by

turning

it

according

to

the

suitable

angle

in

vehicles

and

to

provide

that

inner

and

outer

wheels

turn

differently.

Pinion

gear

and

shaft

at

the

entrance

are

manufactured

as

a

single

part

whereas

they

are

in

different

forms

according

to

automobile

types.

Mirror

gear

which

will

work

with

this

gear

should

become

familiar

before

the

assembly.

In

case

of

any

breakdown,

they

should

be

changed

as

a

pair.

Generally,

in

these

systems

there

are

wear

damages

in

gears.

The

gear

inspected

in

this

study

has

damage

as

a

form

of

shaft

fracture.In

this

study,

failure

analysis

of

the

differential

pinion

shaft

is

carried

out.

Mechanical

characteristics

of

the

material

are

obtained

first.

Then,

the

microstructure

and

chemical

compositions

are

determined.

Some

fractographic

studies

are

2020

Elsevier

Ltd.

All

rights

reserved.Keywords:

Differential;

Fracture;

Power

transfer;

Pinion

shaft

1.

Introduction

The

final-drive

gears

may

be

directly

or

indirectly

driven

from

the

output

gearing

of

the

gearbox.

Directly

driven

final

drives

are

used

when

the

engine

and

transmission

units

are

combined

together

to

form

an

integral

construction.

Indirectly

driven

final

drives

are

used

at

the

rear

of

the

vehicle

being

either

sprung

and

attached

to

the

body

structure

or

unsprung

and

incorporated

in

the

rear-axle

casing.

The

final-drive

gears

are

used

in

the

transmission

system

for

the

following

reasons

[1]:

（a）

to

redirect

the

drive

from

the

gearbox

or

propeller

shaft

through

90°and,（b）

to

provide

a

permanent

gear

reduction

between

the

engine

and

the

driving

road-wheels.

In

vehicles,

differential

is

the

main

part

which

transmits

the

movement

coming

from

the

engine

to

the

wheels

On

a

smooth

road,

the

movement

comes

to

both

wheels

evenly.

The

inner

wheel

should

turn

less

and

the

outer

wheel

should

turn

more

to

do

the

turning

without

lateral

slipping

and

being

flung.

Differential,

which

is

generally

placed

in

the

middle

part

of

the

rear

bridge,

consists

of

pinion

gear,

mirror

gear,

differential

box,

two

axle

gear

and

two

pinion

spider

gears.A

schematic

illustration

of

a

differential

is

given

in

Fig,

1.

The

technical

drawing

of

pinion

the

fractured

pinion

shaft

is

also

given

in

Fig,

2,

Fig.

3

shows

the

photograph

of

the

fractured

pinion

shaft

and

the

fracture

section

is

indicated.In

differentials,

mirror

and

pinion

gear

are

made

to

get

used

to

each

other

during

manufacturing

and

the

same

serial

number

is

given.

Both

of

them

are

changed

on

condition

that

there

are

any

problems.

In

these

systems,

the

common

damage

is

the

wear

of

gears

[2-4].

In

this

study,

the

pinion

shaft

of

the

differential

of

a

minibus

has

been

inspected.

The

minibus

is

a

diesel

vehicle

driven

at

the

rear

axle

and

has

a

passenger

capacity

of

15

people.

Maximum

engine

power

is

90/4000

HP/rpm,

and

maximum

torque

is

205/1600

Nm/rpm.

Its

transmission

box

has

manual

system

（5

forward,

1

back）.

The

damage

was

caused

by

stopping

and

starting

the

minibus

at

a

traffic

lights.

In

this

differential,

entrance

shaft

which

carries

the

pinion

gear

was

broken.

Various

studies

have

been

made

to

determine

the

type

and

possible

reasons

of

the

damage.

These

are:

?

studies

carried

out

to

determine

the

material

of

the

shaft;

?

studies

carried

out

to

determine

the

micro-structure;

?

studies

related

to

the

fracture

surface.

There

is

a

closer

photograph

of

the

fractured

surfaces

and

fracture

area

in

Fig.

4.

The

fracture

was

caused

by

taking

out

circular

mark

gear

seen

in

the

middle

of

surfaces.2.

Experimental

procedureSpecimens

extracted

from

the

shaft

were

subjected

to

various

tests

including

hardness

tests

and

metallographic

and

scanning

electron

microscopy

as

well

as

the

determination

of

chemical

composition.

All

tests

were

carried

out

at

room

temperature.2.1

Chemical

and

metallurgical

analysis

Chemical

analysis

of

the

fractured

differential

material

was

carried

out

using

a

spectrometer.

The

chemical

composition

of

the

material

is

given

in

Table

1.

Chemical

composition

shows

that

the

material

is

a

lowalloy

carburizing

steel

of

the

AISI

8620

type.Hardenability

of

this

steel

is

very

low

because

of

low

carbon

proportion.

Therefore,

surface

area

becomes

hard

and

highly

enduring,

and

inner

areas

becomes

tough

by

increasing

carbon

proportion

on

the

surface

area

with

cementation

operation.

This

is

the

kind

of

steel

which

is

generally

used

in

mechanical

parts

subjected

do

torsion

and

bending.

High

resistance

is

obtained

on

the

surface

and

high

fatigue

endurance

value

can

be

obtained

with

compressive

residual

stress

by

making

the

surface

harder

[5-7].In

which

alloy

elements

distribute

themselves

in

carbon

steels

depends

primarily

on

the

compound

and

carbide

forming

tendencies

of

each

element.

Nickel

dissolves

in

the

α

ferrite

of

the

steel

since

it

has

less

tendency

to

form

carbides

than

iron

Silicon

combines

to

a

limited

extent

with

the

oxygen

present

in

the

steel

to

form

nonmetallic

inclusions

but

otherwise

dissolves

in

the

ferrite.

Most

of

the

manganese

added

to

carbon

steels

dissolves

in

the

ferrite.

Chromium,

which

has

a

somewhat

stronger

carbide-forming

depends

on

the

iron,

partitions

between

the

ferrite

and

carbide

phases.

The

distribution

of

chromium

depends

on

the

amount

of

carbon

present

and

if

other

stronger

carbide-forming

elements

such

as

titanium

and

columbium

amount

of

carbon

present

and

if

other

stronger

carbide-forming

elements

such

as

titanium

and

columbium

are

absent.

Tungsten

and

molybdenum

combine

with

carbon

to

form

carbides

is

there

is

sufficient

carbon

present

and

if

other

stronger

carbide-forming

elements

such

da

titanium

and

columbium

are

absent.

Manganese

and

nickel

lower

the

eutectoid

temperature

[8].Preliminary

micro

structural

examination

of

the

failed

differential

material

is

shown

in

Fig.

5.

It

can

be

seen

that

the

material

has

a

mixed

structure

in

which

some

ferrite

exist

probably

as

a

result

of

slow

cooling

and

high

Si

content.

High

Si

content

in

this

type

of

steel

improves

the

heat

treatment

susceptibility

as

well

asan

improvement

of

yield

strength

and

maximum

stress

without

any

reduction

of

ductility

[9].

If

the

micro-structure

cannot

be

inverted

to

martensite

by

quenching,

a

reduction

of

fatigue

limit

is

observed.There

are

areas

with

carbon

phase

in

Fig.

5（a）.

There

is

the

transition

boundary

of

carburization

in

Fig.

5（b）

and

（c）

shows

the

matrix

region

without

carburization.

As

far

as

it

is

seen

in

there

photographs,

the

piece

was

first

carburized,

then

the

quenching

operation

was

done

than

tempered.

This

situation

can

be

understood

from

blind

martensite

plates.2.2

Hardness

tests

The

hardness

measurements

are

carried

out

by

a

MetTest-HT

type

computer

integrated

hardness

tester.

The

load

is

1471

N.

The

medium

hardness

value

of

the

interior

regions

is

obtained

as

obtained

as

43

HRC.

Micro

hard-ness

measurements

have

been

made

to

determine

the

chance

of

hardness

values

along

cross-section

be-cause

of

the

hardening

of

surface

area

due

to

carburization.

The

results

of

Vickers

hardness

measurement

under

a

load

of

4.903

N

are

illustrated

in

Table

2.2.3

Inspection

of

the

fracture

The

direct

observations

of

the

piece

with

fractured

surfaces

and

SEM

analyses

are

given

in

this

chapter.

The

crack

started

because

of

a

possible

problem

in

the

bottom

of

notch

caused

the

shaft

to

be

broken

completely.

The

crack

started

on

the

outer

part,

after

some

time

it

continued

beyond

the

centre

and

there