Lathe_131903_MANUFACTURING PROCESS 1.ppt

8/17/2019 Lathe_131903_MANUFACTURING PROCESS 1.ppt

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Copyright © The McGraw-Hill Companies, Inc.Permission required or reproduction or display.

PowerPoint to accompany

Krar • Gill • Smid

Technology o Machine Tools!th "dition

The Lathe

Section 11


2/157

History

• Lathe forerunner of all machine tools

• First application was potter's wheel

– Rotated clay and enabled it to be formed intocylindrical shape

• Very versatile (many attachments)

– Used for turnin! taperin! form turnin! screw

cuttin! facin! drillin! borin! spinnin!

rindin and polishin operations

• "uttin tool fed either parallel or riht anles


3/157

Special Types of Lathes

• #nine lathe – $ot production lathe! found in school shops!

toolrooms! and %obbin shops– Basic to all lathes

• &urret lathe

– Used when many duplicate parts reuired – #uipped with multisided toolpost (turret) to

which several different cuttin tools mounted• #mployed in iven seuence


4/157





Engine Lathe Parts

Unit 45


5/157

Engine Lathe

• ccurate and versatile machine

• perations

– &urnin! taperin! form turnin! threadin!facin! drillin! borin! rindin! and polishin

• &hree common

– &oolroom – *eavy+duty

– ,ap+bed


6/157

Lathe Size and Capacity

• -esinated by larest wor. diameter thatcan be swun over lathe ways and enerally

the ma/imum distance between centers• 0anufactured in wide rane of si1es

– 0ost common2 3+ to 45+ in6 swin with

capacity of 78 in6 to 79 feet between centers – &ypical lathe2 74 in6 swin! 8 ft lon bed! 48 in6

– verae metric lathe2 945+445 mm swin and bed lenth of :55 – 4555 mm


7/157Copyright © The McGraw-Hill Companies, Inc. Permission required or reproduction or display.

Indicated y the swingand the length of the ed

Lathe Size


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Parts of the Lathe


!ed

Headstoc"

#$ic"

Change

Gearo%

Tailstoc"

Carriage


9/157

Copyright © The McGraw-Hill Companies, Inc.

Permission required or reproduction or display.


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11/157

Setting Speeds on a Lathe

• ;peeds measured in revolutions per minute – "haned by stepped pulleys or ear levers

•


12/157

Shear Pins and Slip Cl$tches

• >revents damae to feed mechanism fromoverload or sudden torue

• ;hear pins – 0ade of brass

– Found on feed rod! lead screw! and end ear train

• ;prin+loaded slip clutches – Found only on feed rods – ?hen feed mechanism overloaded! shear pin will

brea. or slip clutch will slip causin feed to stop


13/157



;hear pin in end ear

train prevents damae

to the ears in case

of an overload

;prin+ball clutchwill slip when too

much strain is

applied to feed rod


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Lathe Accessories

Unit 46


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+,-./

Lathe 0ccessories

• -ivided into two cateories

– ?or.+holdin! +supportin! and –drivin devices

• Lathe centers! chuc.s! faceplates

• 0andrels! steady and follower rests

• Lathe dos! drive plates

– "uttin+tool+holdin devices• ;traiht and offset toolholders

• &hreadin toolholders! borin bars

• &urret+type toolposts


16/157

+,-.,

Lathe Centers

• ?or. to be turned between centers musthave center hole drilled in each end

– >rovides bearin surface• ;upport durin cuttin

• 0ost common havesolid 0orse taper shan. 85@ centers! steel with carbide tips

• "are to ad%ust and lubricate occasionally

Copyright © The McGraw-Hill Companies, Inc. Permission required or reproduction or display.


17/157

+,-.1

Ch$c"s

• Used e/tensively for holdin wor. for

machinin operations

– ?or. lare or unusual shape

• 0ost commonly used lathe chuc.s

– &hree+%aw universal

– Four+%aw independent

– "ollet chuc.


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+,-.2

Three-3aw 4ni5ersal Ch$c"

• *olds round and he/aonal wor.

• ,rasps wor. uic.ly and accurate withinfew thousandths=inch

• &hree %aws movesimultaneously whenad%usted by chuc. wrench

– "aused by scroll plate intowhich all three %aws fit

• &wo sets of %aw2 outside chuc.in andinside chuc.in



19/157

+,-.6

7o$r-8aw Independent Ch$c"

• Used to hold round! suare! he/aonal! and

irreularly shaped wor.pieces

• *as four %aws

– #ach can be ad%usted independently by chuc.

wrench

• Aaws can be reversed to hold wor. by inside

diameter


20/157

+,-9:

Headstoc" Spindles


Universal and independent chuc. fitted to

three types of headstoc. spindles

76 &hreaded spindle nose

– ;crews on in a

cloc.wise direction

96 &apered spindle nose – *eld by loc. nut

that tihtens on chuc.


21/157

+,-9.

Headstoc" Spindles

46 "am+loc. spindle nose

• *eld by tihtenin cam+loc.s usin &+wrench

• "huc. alined by taper

on spindle nose


Reistration lines on spindle nose

Reistration lines on cam+loc.

"am+loc.s

"am+loc. matin stud on

chuc. or faceplate


22/157

+,-99

Collet Ch$c"

• 0ost accurate chuc.

• Used for hih+precision wor.

• ;prin collets available to hold round!

suare! or he/aon+shaped wor.pieces

•#ach collet has rane of only fewthousandths of an inch over or under si1e

stamped on collet


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+,-9;


B

Collet Ch$c"

;pecial adapter fitted into taper of headstoc. spindle!and hollow draw bar havin internal thread inserted

in opposite end of headstoc. spindle6 Ct draws collet

into tapered adapter causin collet to tihten on wor.piece6

+, 9+


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+,-9+

Types of Lathe


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+,-9/

Types of Lathe


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+,-9,

Left-Hand =ffset Toolholder


• ffset to the riht

• -esined for machinin wor. close to

chuc. or faceplate and cuttin riht to left

• -esinated by letter L

+, 91


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+,-91

)ight-Hand =ffset Toolholder


• ffset to the left

• -esined for machinin wor. close to the

tailstoc. and cuttin left to riht – lso for facin operations

• -esinated by letter R

+, 92


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+,-92

Straight Toolholder

• ,eneral+purpose type

• Used for ta.in cuts in either direction and

for eneral machinin operations

• -esinated by letter ;


+, 96


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+,-96

Toolholders for Inde%ale

Caride Inserts• *eld in holder by cam action or clamps

• &ypes available – "onventional

– &urret+type

– *eavy+duty toolposts

+, ;:


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+,-;:

C$tting-=ff >Parting? Tools

• Used when wor. must be rooved or parted off

• Lon! thin cuttin+off blade loc.edsecurely in toolholder by either cam loc. orloc.in nut

• &hree types of partin toolholders

– Left+hand

– Riht+hand

– ;traiht

+, ;.


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+,-;.

Threading Toolholder

• -esined to hold special form+relieved

thread+cuttin tool

• *as accurately round 85@ anle

– 0aintained throuhout life of tool

• nly top of cuttin surface sharpened when

becomes dull

+, ;9


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+,-;9

S$per #$ic"-Change Toolpost



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Cutting Speed,Feed, and Depth

of Cut Unit 47

+1-;+


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+1-;+

C$tting Speed

• Rate at which point on wor. circumference

travels past cuttin tool

• lways e/pressed in feet per minute (ft=min)

or meters per minute (m=min)

• Cmportant to use correct speed for material

– &oo hih2 cuttin+tool brea.s down rapidly

– &oo low2 time lost! low production rates

+1-;/


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+1-;/

Lathe C$tting Speeds in 7eet and @eters per

@in$te 4sing High-Speed Steel Toolit

Turning and Boring

Rough CutFinish Cut Threading

Materia ft!"in "!"in ft!"in "!"i

Machine steel 90 27 100 30 35 11

Tool steel 70 21 90 27 30 9

Cast iron 60 1 0 24 25

Bron!e 90 27 100 30 25 "l#$in#$ 200 61 300 93 60 1

+1-;,


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+1-;,

Calc$lating Lathe Spindle Speed

• ,iven in revolutions per minute

• "uttin speed of metal and diameter of

wor. must be .nown• >roper spindle speed set by dividin

"; (in=min) by circumference of wor. (in)

-

D/";

-

79/"; r=min ==π

+1-;1


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+1 ;1

E%ampleA

-

D/";

r=min =

"alculate r=min reuired to rouh+turn 9 in6 diameter

piece of machine steel ("; 35)2

7E59

D/35 r=min ==

-

495/"; r=min =0etric Formula

+1-;2


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+1 ;2

Lathe 7eed

• -istance cuttin tool advances alon lenth

of wor. for every revolution of the spindle

• Feed of enine lathe dependent on speed of

lead screw for feed rod

– ;peed controlled by chane ears in

uic.+chane earbo/

+1-;6


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+1 ;6

Two C$ts 4sed to !ring

urpose to remove e/cess material uic.ly

– "oarse feed2 surface finish not too important

• 6575+ to 657:+in6 (569:+ to 56D+mm)

• Finishin cut

– Used to brin diameter to si1e

– Fine feed2 >roduce ood finish

• 6554+ to 655:+in (565+ to 56579+mm)

+1-+:


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+1 +:

7eeds for (ario$s @aterials

>$sing high-speed steel c$tting tool?

Rough Cuts Finish Cut

Materia in# "" in#

Machine steel %010–%020 0%25–0%5 %003–%010

Tool steel %010–%020 0%25–0%5 %003–%010 0%07–

Cast iron %015–%025 0%4–0%65 %005–%012 0%13–

Bron!e %015–%025 0%4–0%65 %003–%010"l#$in#$ %015–%030 0%4–0%75 %005–%010 0%13–

+1-+.


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+1 +.


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#/ample2 -epth of cut on a lathe

+1-+;


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7actors


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Inch System

• "ircumference of crossfeed and compound

rest screw collars divided into 755+79:

eual divisions – #ach has value of 6557 in6

• &urn crossfeed screw cloc.wise 75 raduations!

cuttin tool moved 6575 in6 toward wor.

• Lathe revolves! so 6575 depth of cut ta.en fromentire wor. circumference reducin diameter 6595 in6

• "hec. machine for its' raduations

+1-+/


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=n machines where the wor"piece re5ol5esB

the c$tting tool sho$ld e set in for only half

the amo$nt to e remo5ed from the diameter*

+1-+,


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=n machines where the wor"piece does not

re5ol5eB the c$tting tool sho$ld e set in forthe amo$nt of material to e remo5ed*

+1-+1


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Hints on Grad$ated Collar 4se

76 0a.e sure collar is secure before settin adepth of cut

96 ll depths of cut must be made by feedin

cuttin tool toward wor.piece46 Cf raduated collar turned past desired

settin! must be turned bac.ward half+turnand fed into proper settin to remove

bac.lashD6 $ever hold raduated collar when settin

depth of cut

+1-+2


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:6 ,raduated collar on compound rest can be

used for accurately settin depth of cut• ;houlder turnin• "ompound rest set at 35@ to cross+slide

• Loc. carriae in place

• ;pacin of shoulders to within 6557 in6 accuracy• Facin

• "ompound rest swun to 45@! amount removed fromlenth of wor. G H amount of feed on collar

• 0achinin accurate diameters• ;et compound rest to ED@78' to the cross+slide

• 6557 in movement G 65557+in6 infeed movement

+1-+6


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The compo$nd rest is set at 2+.,D for

ma"ing fine settings*


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Lathe Safet$

Unit 4

+2-/.


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Safety

•


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Safety Preca$tions

• Lathe ha1ardous if not operated properly

• Cmportant to .eep machine and surroundin

area clean and tidy

• ccidents usually caused by carelessness

+2-/;


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Safety Preca$tions

• lways wear approved safety lasses

• Rollup sleeves! remove tie and tuc. in loose

clothin

• $ever wear rin or watch

+2-/+


54/157

Safety Preca$tions

• -o not operate lathe until understand controls

• $ever operate machine if safety uards

removed• ;top lathe before measure wor. or clean! oil

or ad%ust machine

• -o not use ra to clean wor. or machinewhen in operation – Ra can et cauht and dra in hand

+2-//


55/157

Safety Preca$tions

• $ever attempt to stop a lathe chuc. or

driveplate by hand

•


56/157

Safety Preca$tions

• 0ove carriae to farthest position of cut and

revolve lathe spindle one turn by hand

– #nsure all parts clear without %ammin – >revent accident and damae to lathe

• Ieep floor around machine free from rease!

oil! metal cuttins! tools and wor.pieces – il and rease can cause falls

– b%ects on floor become trippin ha1ards

+2-/1


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Safety Preca$tions

• void horseplay at all times

• lways remove chips with brush

– "hips can cause cuts if use hands

– "hips become embedded if use cloths

• lways remove sharp toolbit from

toolholder when polishin! filin! cleanin!or ma.in ad%ustments

P P i t t


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Mounting,Re"o%ing, andAigning Lathe

Centers Unit 49

+6-/6


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&'(ecti%es

& Mo#nt an'(or re$o)e lathe

centers *ro*erl+

& "lign lathe centers ,+ )is#al- trial.

c#t- an' 'ial.in'icator $etho's

+6-,:


60/157

Lathe Centers

• ?or. machined between centers turned for

some portion of lenth! then reversed! and

other end finished• "ritical when machinin wor. between

centers that live center be absolutely true

– "oncentric wor.

+6-,.


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To @o$nt Lathe Centers

• Remove any burrs from lathe spindle!centers! or spindle sleeves

•"lean tapers on lathe centers and inheadstoc. and tailstoc. spindles

• >artially insert cleaned center in lathe spindle

• Force center into spindle

• Follow same procedure when mountintailstoc. center

• "hec. trueness of center

+6-,9


62/157

To )emo5e Lathe Centers

• Live center – Use .noc.out bar pushed throuh headstoc.

spindle (sliht tap)

– Use cloth over center and hold to prevent damae

• -ead center – &urn tailstoc. handwheel to draw spindle bac.

into tailstoc. • #nd of screw contacts end of dead center! forcin it out

of spindle

+6-,;


63/157

0lignment of Lathe Centers

• >arallel diameter produced when lathecenter alined

• &hree common methodsused to alin

76 linin centerlineson bac. of tailstoc.

with each other – nly a visual chec.

and not too accurate


+6-,+


64/157

0lignment of Lathe Centers

96 Usin the trial+cut

method where small

cut ta.en from eachend of wor. and

diameters measured with a micrometer

46 Usin parallel test bar and dial indicator • Fastest and most accurate method


+6-,/


65/157

To 0lign Centers y 0d3$sting

the Tailstoc" 76 Loosen tailstoc. clamp nut or level

96 Loosen on of the ad%ustin screws!

dependin on direction tailstoc. must bemoved and tihten other until line on topalins with line on bottom half

46 &ihten screw to loc. both halves in placeD6 0a.e sure tailstoc. lines still alined

:6 Loc. tailstoc. clamp nut or lever

+6-,,


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To 0lign Centers y

Trial-C$t @ethod76 &a.e a liht cut (J655: in6) to true

diameter from section at tailstoc. end

for 69:5 in6 lon96 ;top feed and note readin on raduated

collar of crossfeed handle

46 0ove cuttin tool away from wor. withcrossfeed handle

D6


67/157

To 0lign Centers y

Trial-C$t @ethod

:6 Return cuttin tool to same raduated

collar settin as at section 86 "ut a 6:55+in (74 mm) lenth at section <

and stop lathe

6 0easure both diameters with micrometer

+6-,2


68/157

To 0lign Centers y

Trial-C$t @ethodE6 Cf both diameters not same si1e! ad%ust

tailstoc. either toward or away from

cuttin tool H difference of two readins

36 &a.e another liht cut at and < at same

crossfeed raduated collar settin6

0easure diameters and ad%ust tailstoc.6

+6-,6


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To 0lign Centers 4sing


70/157



71/157



72/157






)rinding LatheCutting Toos

Unit 50

/:-1;


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Grinding Lathe C$tting Tool

• ?ide variety of cuttin tools for lathe – ll have certain anles and clearances reardless

of shape

Shape and


74/157

To Grind a

General-P$rpose Toolit76 -ress face of rindin wheel

96 ,rip toolbit firmly! supportin hands on rinder

toolrest46 *old toolbit at proper

anel to rind cuttinede anle

• &ilt bottom of toolbittoward wheel andrind 75@ side relief or clearance anle


/:-1/


75/157

"uttin ede J H Cn lon and e/tendover K width of toolbit

75@ side relief or

clearance anle


/:-1,


76/157

D6 ?hile rindin! move toolbit bac. and

forth across face of wheel• >revents roovin wheel

:6 &oolbit must be cooled freuently durin

rindin• Never overheat toolbit

• Never uench stellite or cemented+carbide

tools• Never rind carbides with aluminum o/ide

wheel

/:-11


77/157

86 ,rind end cuttin ede so it forms anle of

a little less than 35@ with side cuttin ede – *old tool so that end cuttin ede anle and

end relief anle of 7:@ round at same time


1: to 2: Point 0ngle

/:-12


78/157

6 Usin toolbit rindin ae! chec. amount

of end relief when toolbit is in toolholder


/:-16


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E6 *old top of toolbit appro/imately D:@ to

a/is of wheel and rind side ra.e toappro/imately 7D@

– -o not rind below top of toolbit

• "reates a chip trap


Side ra"e gro$nd the length

of the c$tting edge

/:-2:


80/157

36 ,rind sliht radius on point of cuttin

tool! bein sure to maintain same frontand side clearance anle

756 ?ith oilstone! hone cuttin ede of toolbit

slihtly• Lenthen life of toolbit

• #nable it to produce better surface finish on

wor.piece



81/157






MachiningBet*een Centers

Unit 52

/9-29


82/157

@achining !etween Centers

• &rainin prorams (schools) – Remove and replace wor. in lathe many times

before completed

– $eed assurance that machined diameter will runtrue with other diameters

• 0achinin between centers saves time in settin up

• "ommon operations – Facin! rouh and finish+turnin! shoulder

turnin! filin and polishin

/9-2;


83/157

Setting 4p a C$tting Tool

76 0ove toolpost to the left+hand side of the &+slotin thecompoundrest

96 0ount tool+holder intoolpost sosetscrew intoolholder 7 in6

beyond toolpost


/9-2+


84/157


Hea5y C$tsA Set toolholder at right

angles to wor"

/9-2/


85/157

Setting 4p a C$tting ToolA cont*

46 Cnsert proper cuttin tool into toolholder!havin tool e/tend 6:55 in6 beyond

toolholder and never more than twice its

thic.nessD6 ;et cuttin+tool point to center heiht

• "hec. it aainst lathe center point

:6 &ihten toolpost securely to prevent itfrom movin durin a cut

/9-2,


86/157

P$rposes of a Trial C$t

• >roduce accurate turned diameter

– 0easured with micrometer

• ;et cuttin+tool point to the diameter

• ;et crossfeed micrometer collar to the

diameter

/9-21


87/157

Proced$re to Ta"e a Trial C$t

76 ;et up wor.piece and cuttin tool as for

turnin

96 ;et proper speeds and feed to suit material

46 ;tart lathe and position toolbit over wor.

appro/imately 679: in6 from end

D6 &urn compound rest handle cloc.wise K

of a turn to remove any bac.lash

/9-22


88/157

:6 feed toolbit into wor. by turnin crossfeedhandle cloc.wise until liht rin appearsaround entire circumference of wor.

86 -o $& move crossfeed handle settin

6 &urn carriae handwheel until toolbit

clears end of wor.piece by about 6585 in6E6 &urn crossfeed handle cloc.wise about 6

575 in6 and ta.e trial cut 69:5 in6 alon

lenth of wor. 36 -isenae automatic feed and clear toolbit

past end of wor. with carriae handwheel

/9-26


89/157

756 ;top the lathe

776 &est accuracy of micrometer by cleaninand closin measurin faces and then

measure trial+cut diameter

796 "alculate how much material must still be

removed from diameter of wor.

746 &urn crossfeed handle cloc.wise H

amount of material to be removed

/9-6:


90/157

7D6 &a.e another trial cut 69:5 in6 lon and

stop the lathe7:6 "lear toolbit over end of wor. with

carriae handwheel

786 0easure diameter and read%ust crossfeed

handle until diameter is correct

76 0achine diameter to lenth

/9-6.


91/157

)o$gh T$rning

• Removes as much metal as possible inshortest lenth of time

•ccuracy and surface finish are notimportant in this operation – 6595+ to 6545+in6 feed recommended

• ?or. rouh+turned to

– ?ithin 6545 in6 of finished si1e when removinup to 6:55 in6 diameter

– ?ithin 6585 in6 when removin M 6:55 in6

/9-69


92/157

Proced$re for )o$gh T$rning

76 ;et lathe to correct speed for type and si1eof material bein cut

96 d%ust uic.+chane earbo/ for a 6575+to 6545+in6 feed

• -epends on depth of cut and condition ofmachine

46 0ove toolholder to left+hand side ofcompound rest and set toolbit heiht tocenter

/9-6;


93/157

D6 &ihten toolpost securely to prevent

toolholder from movin durin machinin:6 &a.e liht trial cut at riht+hand end of

wor. for a 69:5 in6 lenth

86 0easure wor. and ad%ust toolbit for proper depth of cut

6 "ut alon for 69:5 in6! stop lathe! andchec. diameter for si1e

76 -iameter 6545 in6 over finish si1e

E6 Read%ust depth of cut! if necessary

/9-6+


94/157

7inish T$rning

• Follows rouh turnin

• >roduces smooth surface finish and cuts

wor. to an accurate si1e

• Factors affectin type of surface finish

– "ondition of cuttin tool

– Riidity of machine and wor.

– Lathe speeds and feeds

/9-6/


95/157

Proced$re 7or 7inish T$rning

76 0a.e sure cuttin ede of toolbit free

from nic.s! burrs! etc6

96 ;et toolbit on centerN chec. it aainst lathe

center point

46 ;et lathe to recommended speed and feed

/9-6,


96/157

D6 &a.e liht trial cut 69:5 in6 lon at riht+

hand end of wor. • >roduce true diameter

• ;et cuttin tool to diameter

• ;et raduated collar to diameter

:6 ;top lathe and measure diameter

86 ;et depth of cut for half amount ofmaterial to be removed

6 "ut alon for 69:5 in6! stop lathe! chec.

E6 Read%ust depth of cut and finish+turn

/9-61


97/157

7iling in a Lathe

• nly to remove small amount of stoc.!remove burrs! or round off sharp corners

• ?or. should be turned to within 6559 to 6554in6 of si1e

• For safety! file with left hand so arms andhands .ept clear of revolvin chuc.

• Remove toolbit from toolholder before filin

• "over lathe bed with paper before filin

/9-62


98/157

Proced$re to 7ile in a Lathe

76 ;et spindle speed to twice that for turnin

96 0ount wor. between centers! lubricate!

and carefully ad%ust dead center in wor. 46 0ove carriae as far to riht as possible

and remove toolpost

D6 -isenae lead screw and feed rod:6 ;elect 75+ or 79+in6 mill file or lon+anle

lathe file

/9-66


99/157

86 ;tart lathe

6 ,rasp file handle in left hand and supportfile point with finers of riht hand


/9-.::


100/157

E6 pply liht pressure and push file forwardto its full lenthN release pressure onreturn stro.e

36 0ove file about half width of file for eachstro.e and continue filin until finished

• Use 45+D5 stro.es per minute756 ;afety precautions

• Roll sleeves above elbow

• Remove watches and rins

• $ever use file without properly fitted handle• $ever apply too much pressure

• "lean file freuently with file brush

/9-.:.

P d f


101/157

Proced$re forPolishing in a Lathe

76 ;elect correct type and rade of abrasivecloth for finish desired

• >iece about 8 – E in6 lon and 7 in6 wide• Use aluminum o/ide abrasive cloth forferrous metals

• Use silicon carbide abrasive cloth should be

used for nonferrous metals96 ;et lathe to run at hih speed

46 -isenae feed rod and lead screw

/9-.:9


102/157

D6 Remove toolpost and toolholder

:6 Lubricate and ad%ust dead center 86 Roll sleeves up above elbows and tuc. in

any loose clothin

6 ;tart latheE6 *old abrasive cloth on wor.

36 ?ith riht hand! press cloth firmly on

wor. while tihtly holdin other end ofabrasive cloth with left hand

756 0ove cloth slowly bac. and forth

/9-.:;


103/157

Sho$lder

• ;houlder2 the chane in diameters! or step!

when turnin more than one diameter on a

piece of wor. • &hree common types of shoulders

– ;uare

– Filleted – nular or &apered



/9-.:+

f S


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Three Types of Sho$lders





105/157





+nuring,)roo%ing,

and For" Turning Unit 53

/;-.:,


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Kn$rling

• >rocess if impressin a diamond+shaped or

straiht+line patter into the surface of the

wor.piece – Cmprove its appearance

– >rovide better rippin surface

– Cncrease wor.piece diameter when press fitreuired

/;-.:1


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Kn$rling

• -iamond+ and

straiht+pattern

rolls available inthree styles

– Fine

– 0edium

– "ourse


/;-.:2


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Kn$rling Tool

• &oolpost+type toolholder on which pair of

hardened+steel rolls mounted

Inurlin tool with

one set of rolls in

self+centerin head

Inurlin tool with

three sets of rolls

in revolvin head


/;-.:6

4 i l K li T l S t


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4ni5ersal Kn$rling Tool System

• -ovetailed shan. and as many as seven

interchaneable .nurlin heads that can

produce wide rane of .nurlin patterns• "ombines in one tool

– Versatility

– Riidity

– #ase of handlin

– ;implicity

/;-..:

P d K l i L h


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Proced$re to Kn$rl in a Lathe

76 0ount wor. between centers and mar.

reuired lenth to be .nurled

•Cf wor. held in chuc. for .nurlin! riht endof wor. should be supported with revolvin

tailstoc. center

96 ;et lathe to run at one+uarter speed

reuired for turnin

46 ;et carriae feed to 657: to 6545 in6

/;-...


111/157

D6 ;et center of floatin head of .nurlin tool

even with dead+center point


:6 ;et .nurlin tool at riht anles to

wor.piece and tihten it securely

/;-..9

8 ; hi d li h l h ll


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86 ;tart machine and lihtly touch rolls

aainst wor. to chec. trac.in6 0ove .nurlin tool to end of wor. so

only half the roll face bears aainst wor.

E6 Force .nurlin tool into wor.appro/imately 659: in6 and start lathe

R

;tart lathe and then force .nurlin tool intowor. until diamond pattern come to point

/;-..;


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36 ;top lathe and e/amine pattern

756 nce pattern correct! enae automaticcarriae feed and apply cuttin fluid to.nurlin rolls

776 Inurl to proper lenth and depth• -o not disenae feed until full lenth has

been .nurledN otherwise! rins will be formedon .nurled pattern

796 Cf .nurlin pattern not to point after lenthhas been .nurled! reverse lathe feed andta.e another pass across wor.

/;-..+


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Groo5ing


S$are

)o$nd

(-shaped

• -one at end of thread to

permit full travel of nut up

to a shoulder or at ede of

shoulder for proper fit• lso called recessin!

undercuttin! or nec.in

• Rounded rooves usedwhere there is strain on

part

/;-../


115/157

Proced$re to C$t a Groo5e

76 ,rind toolbit to desired si1e and shape of

roove reuired

96 Lay out location of roove

46 ;et lathe to half the speed for turnin

D6 0ount wor.piece in lathe

:6 ;et toolbit to center heiht

/;-..,


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86 Locate toolbit on wor. at position whereroove is to be cut

6 ;tart lathe and feed cuttin tool towardwor. usin crossfeed handle until toolbitmar.s wor. lihtly

E6 *old crossfeed handle in position and setraduated collar to 1ero

36 "alculate how far crossfeed screw must be

turned to cut roove to proper depth756 Feed toolbit into wor. slowly usin

crossfeed handle

/;-..1


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776 pply cuttin fluid to point of cuttin tool

• &o ensure cuttin tool will not bind inroove! move carriae slihtly to left and to

riht while roovin

• ;hould chatter develop! reduce spindle speed

796 ;top lathe and chec. depth of roove with

outside calipers or .nife+ede verniers

Safety noteA 0lways wear safety goggles when

groo5ing on a lathe



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Threads andThread Cutting

Unit 55

//-..6


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Threads

• Used for hundreds of years for holdin parts

toether! ma.in ad%ustments! and

transmittin power and motion• rt of producin threads continually

improved

• 0assed+produced by taps! dies! threadrollin! thread millin! and rindin

//-.9:


120/157

Threads

• &hread – *elical ride of uniform section formed on

inside or outside of cylinder or cone

• Used for several purposes2 – Fasten devices such as screws! bolts! studs! and

nuts

– >rovide accurate measurement! as in micrometer – &ransmit motion

– Cncrease force

//-.9.


122/157

Thread Terminology

• ;crew thread

– *elical ride of uniform section formed on

inside or outside of cylinder or cone

• #/ternal thread

– "ut on e/ternal surface or cone

• Cnternal thread – >roduced on inside of cylinder or cone

//-.9;

• 0a%or diameter


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• 0a%or diameter – Larest diameter of e/ternal or internal thread

• 0inor diameter – ;mallest diameter of e/ternal or internal thread

• >itch diameter – -iameter of imainary cylinder that passes

throuh thread at point where roove and threadwidths are eual

– #ual to ma%or diameter minus sinle depth ofthread

– &olerance and allowances iven at pitchdiameter line

//-.9+

• $umber of threads per inch


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• $umber of threads per inch

– $umber of crests or roots per inch of threaded

section (-oes not apply to metric threads)

• >itch

– -istance from point on one thread to

correspondin point on ne/t thread! measured

parallel to a/is

– #/pressed in millimeters for metric threads

• Lead – -istance screw thread advances a/ially in one

revolution (sinle+start thread! lead G pitch)

//-.9/

• Root


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• Root –


126/157

//-.91

• Riht hand thread


127/157

• Riht+hand thread

– *elical ride of uniform cross section onto

which nut is threaded in cloc.wise direction

– ?hen cut on lathe! toolbit

advanced from riht to left

• Left+hand thread

– *elical ride of uniform cross section onto

which nut is threaded in countercloc.wise

direction – ?hen cut on lathe! toolbit

advanced from left to riht



//-.92

Th d 7


128/157

Thread 7orms

• pril! 73: C; came to an areement

coverin standard metric thread profile

– ;pecifies si1es and pitches for various threadsin new C; 0etric &hread ;tandard

– *as 9: thread si1es! rane in diameter from 768

to 755 mm

– Cdentified by letter 0! nominal diameter! and

pitch @ / F :*2

//-.96

0merican &ational Standard Thread


129/157


• -ivided into four main series! all havinsame shape and proportions – $ational "oarse ($")

– $ational Fine ($F) – $ational ;pecial ($;)

– $ational >ipe ($>&)

• *as 85@ anle with root and crest truncatedto 7=Eth the pitch

• Used in fabrication! machine construction

//-.;:



130/157

N P F

N P D

679:or/679:

6874Dor/874D6

=

=



//-.;.

4nified Thread


131/157

4nified Thread

• -eveloped by U6;6!


132/157

N

P F

N P F

N P D

N

69:5or/69:5thread)(internal

679:or/679:thread)(e/ternal

6:D74or/:D746thread)(internal

=

=

=



//-.;;

0merican &ational 0cme Thread


133/157

0merican &ational 0cme Thread

• Replacin suare thread in many cases

• Used for feed screws! %ac.s! and vises D / minimum .500P

/ maximum .500P 0.010

F / .3707P

C / .3707P . .0052 (for maximum depth)



//-.;+

! Sh Th d


134/157

!rown Sharpe orm Thread

• Used to mesh worm ears and transmitmotion between two shafts at riht anles toeach other but not in same plane

D / .6866P

F / .335P

C / .310P



//-.;/

S are Thread


135/157

S$are Thread

•


136/157

International @etric thread

• ;tandardi1ed thread used in #urope

F G 5679: P

R G 565844 P (ma/imum) G 565:D P (minimum)

D G 5654: P (ma/imum)

G 568E:: P (minimum)



//-.;1

Thread 7its and Classifications


137/157

Thread 7its and Classifications

• Fit – Relationship between two matin parts

– -etermined by amount of clearance or

interference when they are assembled

• $ominal si1e – -esination used to identify si1e of part

• ctual si1e – 0easured si1e of thread or part

–


138/157

0llowance

• >ermissible difference between lareste/ternal thread and smallest internal thread

• -ifference produces tihtest fit acceptable

for any iven classification&he allowance for a 7 in6PE U$" "lass 9 and 9< fit is2

0inimum pitch diameter of the

internal thread (9


139/157

Tolerance

• Variation permitted in part si1e

• 0ay be e/pressed as plus! minus! or both

• &otal tolerance is sum of plus and minus tolerances

• Cn Unified and $ational systems! tolerance is pluson e/ternal threads and minus on internal threads

0a/imum pitch diameter of the

e/ternal thread (9) G 6378E in60inimum pitch diameter of the

e/ternal thread (9) G 63755 in6

&olerance G 6558E in6

&he tolerance for a 7 in6PE U$" "lass 9 thread is2

//-.+:

Limits


140/157

Limits

• 0a/imum and minimum dimensions of part

0a/imum pitch diameter of the

e/ternal thread (9) G 6378E in66

0inimum pitch diameter of the

e/ternal thread (9) G 63755 in6

&he limits for a 7 in6PE U$" "lass 9 thread are2

//-.+.

Three Categories of 4nified


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gThread 7its

• #/ternal threads classified as 7! 9! and 4 andinternal threads as 7

• "lasses 7 and 7<

– &hreads for wor. that must be assembled – Loosest fit

• "lasses 9 and 9< – Used for most commercial fasteners

– 0edium or free fit• "lasses 4 and 4<

– Used where more accurate fit and lead reuired

– $o allowance provided

//-.+9

Thread Calc$lationsA E%ample .


142/157

Thread Calc$lationsA E%ample .

&o cut a correct thread on a lathe! it is necessary first to ma.ecalculations so thread will have the proper dimensions6

D / single depth of thread

P / pitch

in665876755/6874D4

/874D46

in67556

75

77

==

=

===

P Dtpi

P

"alculate pitch! depth! minor diameter! and width of flat

for a QP75 U$" thread6

in6579:6

75

7 /

E

7

E flatof ?idth

in689E6

6587)(6587+6:

)(+dia0a%ordia0inor

=

==

=

+=

+=

P

D D

//-.+;

Thread Calc$lationsA E%ample 9


143/157

Thread Calc$lationsA E%ample 9

P / pitch = 1 mm

D / 0.54127 x 1

= 0.54 mm

?hat are the pitch! depth! minor diameter! width of crest

and width of root for an 0 864 7 threadS

mm79:65

7/79:65

/679:5crestof ?idth

mm996:

6:D)(6:D+864

)(+dia0a%ordia0inor

=

=

=

=

+=

+=

P

D D

mm9:65

7/569:

/9:65rootof ?idth

=

=

= P

//-.++

Proced$re to Set the #$ic"-


144/157

#Change Gearo% for Threading

76 "hec. drawin for thread pitch reuired

96 From chart on uic.+chane earbo/! find

whole number that represents pitch inthreads per inch or in millimeters

46 ?ith lathe stopped! enae tumbler lever

in hole! which is in line with the pitchD6 ;et top lever in proper position as

indicated on chart

//-.+/

: # lidi i t i d


145/157

:6 #nae slidin ear in or out as reuired

86 &urn lathe spindle by hand to ensure thatlead screw revolves

6 Rechec. lever settins to avoid errors

//-.+,

Thread-Chasing dial


146/157

Thread Chasing dial

• Lathe spindle andlead screw must bein same relative

position for each cut

– &hread+chasin dialattached to carriae for this purpose

• -ial has eiht divisions – #ven threads use any division

– dd threads either numberedor unnumbered2 not both



//-.+1

Thread C$tting


147/157

Thread C$tting

• >roduces a helical ride of uniform section

on wor.piece

• >erformed by ta.in successive cuts withthreadin toolbit of same shape as thread

form reuired

• ?or. may be held between centers or inchuc.

//-.+2

Proced$re to Set 4p a Lathe for


148/157

Threading >,: Thread?

76 ;et lathe speed to K speed used for turnin

96 ;et uic.+chane earbo/ for reuired pitch

in threads per inch or in millimeters46 #nae lead screw

D6 ;ecure 85@ threadin toolbit and chec.

anle usin thread center ae:6 ;et compound rest at 93@ to rihtN set to left

for left+hand thread

//-.+6

8 ;et cuttin tool to heiht of lathe center


149/157

86 ;et cuttin tool to heiht of lathe center

point6 0ount wor. between centers

• 0a.e sure lathe do is tiht on wor.

• Cf wor. mounted in chuc.! it must be heldtihtly

E6 ;et toolbit at riht anles to wor.! usin

thread center ae

36 rrane apron controls to allow split+nut

lever to be enaed

//-./:

Thread-C$tting =peration


150/157

Thread-C$tting =peration

Proced$re to c$t a ,: thread

76 "hec. ma%or diameter of wor. for si1e

96 ;tart lathe and chamfer end of wor.piecewith side of threadin tool to %ust below

minor diameter of thread

46 0ar. lenth to be threaded by cuttinliht roove at this point with threadin

tool while lathe revolvin

//-./.

D6 0ove carriae until point of threadin tool


151/157

p

near riht+hand end of wor.

:6 &urn crossfeed handle until threadin tool

close to diameter! but stop when handle is at

4 o'cloc. position86 *old crossfeed handle in this position and

set raduated collar to 1ero

6 &urn compound rest handle until threadintool lihtly mar.s wor.

//-./9

E6 0ove carriae to riht until toolbit clears


152/157

E6 ove ca ae to t u t too b t c ea s

end of wor. 36 Feed compound rest cloc.wise about 6554 in6

756 #nae split+nut lever on correct line of

thread+chasin dial and ta.e trial cut alonlenth to be threaded

776 t end of cut! turn crossfeed handle

countercloc.wise to move toolbit away from

wor. and disenae split+nut lever

//-./;

796 ;top lathe and chec. number of tpi with


153/157

p p

thread pitch ae! rule! or center ae746 fter each cut! turn carriae handwheel to

brin toolbit to start of thread and return

crossfeed handle to 1ero7D6 ;et depth of all threadin cuts with

compound rest handle

• ;ee &able ::69 and &able ::64

//-./+

hen tool is fed in at 96B most of the c$tting

i i f i


154/157

is done y the leading edge of toolit*



//-.//

Ta'e 55#- Depth settings forcutting ./0 nationa for"


155/157

cutting ./ nationa for"

threadsCo"pound Rest Settingtpi /0 2/0 -30

24 %027 %031 %030

20 %0325%0375%0371 %036 %0417%041

16 %0405%046%046

14 %0465%0537%0525

13 %050 %0577%057

11 %059 %06 %0674

Portion of tale ta"en

from te%too"

//-./,

7:6 pply cuttin fluid and ta.e successive


156/157

pp y

cuts until top (crest) and bottom (root) ofthread are same width

786 Remove burrs from top of thread with file

76 "hec. thread with master nut and ta.efurther cuts

//-./1

Si% ays to Chec" Threads


157/157

Si% ays to Chec" Threads

• -epends on accuracy reuired2

76 0aster nut or screw

96 &hread micrometer 46 &hree wires

D6 &hread roll or snap ae

:6 &hread rin or plu ae8 i l

Lathe_131903_MANUFACTURING PROCESS 1.ppt

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Transcript of Lathe_131903_MANUFACTURING PROCESS 1.ppt