unit-ii-capstan & turret lathe
TRANSCRIPT
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INTRODUCTION
It is a production lathe used in many industries formass production of identical components
It is a development of engine lathes
It was rst developed in the United States y !rattand "hitney in #$%&
It consists of a ed' all geared headstoc(' and asaddle on which a four station tool post is mounted )
Tailstoc( of an engine is replaced y a he*agonalturret'on the face of which multiple tools may etted and fed into the wor( in proper se+uence)
,dvantage is that several di-erent types ofoperations can e done on a wor( piece without re.setting of wor( or tools)
, numer of identical parts can e produced in the
minimum time)
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Di-erences /w 0ngine lathe
and Capstan/turret lathe Capstan/turret
1athe
2ore tool posts) No tail stoc() 2anual inde*ing) Operational time
is lesser) Semi s(illed laorfor operation)
0ngine 1athe
Only one tool post)
It has tail stoc()
No inde*ing )
Operational time is
more S(illed wor(ers have
to operate)
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No lead screw) 3igh +uality of
accuracy) It is used for mass
production wor() It ta(es lesser time
as changing of
wor( is automatic) 2inimum of #4hp
motor is re+uiredto run the head
stoc() It ta(es more time
in setting up thetool)
as ow accuracy)
It is usedaccording to 5o
order) It ta(es more as
changing of wor( ismanual)
2inimum of 4hpmotor is re+uiredto run the headstoc()
It ta(es less timein setting up tool)
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!RINCI!,1 !,RTS O6
C,!ST,N 7TURR0T 1,T30
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C,!ST,N 1,T30
Capstan lathes are widely used in the precisionauto turned component manufacturer)
8ives a large volume production' high
accuracy' very versatile and maintenance.free) ,ll the machine operations li(e turning'
facing' oring' drilling and tapping can edone oth in ferrous and nonferrous materials)
0ven uns(illed laour can operate this machinevery easily)
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O!0R,TION
It carries the he*agonal turret on a ramor a short slide)
Ram slides longitudinally on a saddlepositioned and clamped on lathe ed
way) This machine is used for machining ar
of smaller diameter) Tools are mounted on the s+uare turret
and si* faces of the he*agonal turret) 6eeding movement is otained whenram moves from left to right)
"hen the ram is moved ac(wards andturret inde*es automatically and thetools mounted on the ne*t face comes
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TURR0T 1,T30
Introduction
It is mounted directly on a saddle and thewhole unit moves ac( 7 forth
Turret lathe is heavier in construction
It is particularly adapted for larger diameterarwor( 7 chuc(ing wor(
2achine can accommodate longer wor(pieces than in a capstan lathe
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O!0R,TION
In a turret lathe' a longitudinally feed ale'he*agon turret replaces the tailstoc()
Turret on which si* tools can e mounted' cane rotated aout a vertical a*is to ring each
tool into operating position) 0ntire unit can e moved longitudinally' eithermanually or y power to provide feed for thetools)
"hen the turret assemly is ac(ed away from
the spindle y means of a capstan wheel' turretinde*es automatically at the end of itsmovement thus ringing each of the si* toolsinto operating position)
S+uare turret on the cross slide can e rotatedmanually aout a vertical a*is to ring each of
the four tools into operating position)
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On most machines' the turret can e movedtransversely' either manually or y power' ymeans of the cross slide' and longitudinally
through power or manual operation of thecarriage) In most cased' a *ed tool holder alsois added to the ac( end of the cross slide9 thisoften carries a parting tool
, numer of tools can e set on the machineand then +uic(ly e rought successively intowor(ing position so that a complete part cane machined without the necessity for furtherad5usting' changing tools' or ma(ingmeasurements)
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,D:,NT,80S O6 TURR0T 1,T30S
#) Tools may e set up in the turret in the properse+uence for the operation);) 0ach section is provided with a feed trip so
that each cut of the tool is the same as theprevious cut)
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DIS2I1,RITI0S >0T"00NC,!ST,N 7 TURR0T 1,T30
Turret of capstan lathe is mounted on ashort slides on a saddle) The saddle isclamped on ed ways after ad5ustingthe length of the wor( piece)
In case of turret lathe 'the turret ismounted on the saddle which slidesdirectly on the lathe ed ways) Thistype of construction provides utmost
rigidity to the tool post)
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CAPSTAN AND TURRET LATHE
SLIDE ARRANGEMENT
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In case of capstan lathe as the ram feeds intothe wor(' the overhanging of the ram from thestationary saddle presents a non rigidconstruction)
Turret lathe can operate under severe cuttingconditions ' accommodating heavier wor(pieces with higher cutting speeds)
1arger and heavier chuc(ing wor(s are usuallyhandled on a turret lathe)
Capstan lathe is suitale only for ar wor() Capstan lathes are particularly handy for small
articles which re+uire light and fast cuts) In turret lathes the hand feeding is laorious
process which ma(es it unsuitale for smallarticles)
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1arger and heavier chuc(ing wor(s are usuallyhandled on a turret lathe)
Capstan lathe is suitale only for ar wor() Capstan lathes are particularly handy for small
articles which re+uire light and fast cuts)
In turret lathes the hand feeding is laorious
process which ma(es it unsuitale for smallarticles)
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Drilling machine
Drilling: Operation through which holes are produced in asolid metal by revolving tool (drill). Drills are commonly used in woodworking and
metalworking. Drilling doesnt produce perfectly true hole (Basic operation)
ole is generated by rotating edge of a cutting tool knownas drill which e!erts large force on the work.
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Classifcation o Drills "ccording to type of shank:
#arallel $hank %aper $hank
"ccording to type of flute: &lat'$pade drills %wist Drills #arallel %aper*
"ccording to length:
$hort series drills $tub series drills +ong $eries drills
"ccording to applications: ,ore drills Drills for long hole drilling
,entre drills -asonary drills "ccording to tool material:
igh $peed drills ,arbide tipped drills
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Classification of Drilling Machines
#ortable drilling machine $ensitive or bench drilling machine pright drilling machine /adial drilling machine
-ultiple spindle drilling machine Deep hole drilling machine 0ang drilling machine ori1ontal drilling machine"utomatic drilling machine
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Tools or Drilling
&lat'$pade drills:2t carries a flat section at cutting edge-aterial used is carbon steel '$$2t has been obsolete due to many reasons
$till used for small special works %wist drills:-ost widely used for numerous operations-aterial used is $$"vailable in various si1es
$ub types: %aper shank #arallel shank
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"ccording to 2ndian $tandards3 drills are specified:
Diameters $eries -aterial 2.$. number
%ypes: %ype 4 5 4ormal low carbon steel %ype 5 ard materials %ype $ 5 $oft tough materials
6!: 7.89 2$: 89 $:; %wist drill of 7.8 mm 2$:89refers drill made from igh speed steel 2f material is not specified3 type 4 should be taken.
4ormal si1es: In metric sizes, drill dia range from 0.2mm to100mm
Drill size & specification
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Drilling Machines
#ortable drilling machines:$mall3 compact self; contained with small
electric motor.
+ight in weight easily handled."vailable in different si1es capacities
(wider range of holes)
pto ma!imum diameter of
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Sensitive (Bench Drill) Useful for light work Simple construction Consists of iron base(9), ertical column (!),
swiel table("), swiel table clamp(#),electricmotor ($), fee% han%le (),spin%le ('), %rillchuck ()
op of column is proi%e% with %rie consistsof en%less belt running oer *+pulles-
.ne pulle is mounte% on motor shaft & other
on machine spin%le *ertical moement proi%e% b fee% han%lethrough a rack & pinion arrangement-
Drills haing up to /mm %rilling capacit canbe use%-
Drills rotate at er high spee% 0an% fee% enables operator to feel gra%ual
penetration of %rill into work material & eensense obstruction-
1en it can be sense% whether %rill is cuttingproperl
2or these reasons it is known as sensitie%rills
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3a%ial %rilling machine
Useful commonl for its wi%er action
Single spin%le %rilling machines 0as ertical column with ra%ial arm 4rm can swing through $#/%eg Use% for reaming an% tapping Spee% ar from / 5 $"// rpm Consists of iron base, ertical
column, horizontal moing arm, %riespin%le, %rill chuck, interlockingclamping leers etc
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Gang drilling machine
< or more drill heads mounted on same table
6ach spindle has independent set of speed and
depth
-ovement of =obs are fast
#roduction is at faster rate "pplications: -ultiple hole drilling in pipes3 plates
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Multiple spindle drilling machine
Drills several holes simultaneously of differentsi1es
igh production rate "ll spindles have same drive
Drill heads has capacity to drive up to 89spindles simultaneously
$pindles can be placed in different positions toenable drilling of holes at any location
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Upright drilling machine
$everal spindle speed are available
2deally suited for small and big shops
Designed for heavier work
-ounted on a column
$pecified by dist. b'w spindle column
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Deep drilling machines
sed for holes whose length e!ceed >
times the drill si1e
+ike for barrels of guns and tanks
%hey are of vertical and hori1ontal type
igh speed low feed machine tool
?ertical or hori1ontal spindle drive
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Automatic drilling machine
&or high production work Different operations are performed in se@uence at successive
work station "t each workstation3 operation se@uence3 related cutting speeds3
start finish of operation are arranged in synchroni1ed manner.
as inde!ing table and work holding fi!tures as multiple stations as multiple spindles in various orientations $everal operations like drilling3 boring3 tapping3 etc can be
performed
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Drilling operations
Drilling
/eaming
Boring
,ounter boring
,ounter sinking
$pot facing
%apping
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Drilling: 2t is main operation done onthis machine3 producing a hole bymeans of revolving tool (drill)
/eaming: Operation of finishing ahole to bring it to accurate si1e andhave better surface finish (reamer)#roduces straight3 smooth andaccurate hole.
Boring:Operation of enlarging a holeto bring it to re@uired si1e and havebetter finish. "lso used for correctinghole location out of roundness
,ounter boring: Operation ofenlarging only a limited portion ofhole. 2t is performed by means ofcounter boring tool (double toolboring bar)
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,ounter sinking: Operation usedfor enlarging end of hole to give it aconical shape for short distance.
seful in providing a seat forcountersunk heads of screws
$pot facing: Operation used fors@uaring finishing the surfacearound at end of a hole to
provide a smooth true seat tounder seat of bolt heads or collars
%apping: Operation for forminginternal threads by means of tool(tap)
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wistDrills 2t is a cylindrical body carrying two spiral flutes cut on it. 2t consists of two main parts:
$hank (gripped in drill chuck) Body (-ain cutting unit)
$hank carry a tang at end to ensure a firm grip Body consists of flute (removal of chips)3 lips' cutting edges3
point or dead centre3 land (guides drill in hole) relief' body
clearance
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igh eli!: ,arry a heli! angle of >89to A99 a heavy web groove width
is larger than that of usual twist drill (easier @uicker disposal
of chips) +arge employed for deep hole drilling &ast spiral drills*
+ow eli!: ,arry smaller heli! angle are relatively more rigid. ,apable of higher tor@ue heavier feeds slow spiral drills*
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Drilling parameters
,utting $peed: /efers to peripheral speed of a point on the surface of a point on
the surface of drill bit in contact with work. (m'min) ? (>.ACDC4)'999 m'min
&eed (f):
2t is the distance the drill moves into work at each revolution ofdrill spindle (mm'rev)
Depth of cut (t): 2t is e@ual to one half of the diameter. t D'< mm
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Milling
-illing is one of the basic machining processes.-illing is a very versatile process capable of
producing simple two dimensional flat shapes to
comple! three dimensional interlaced surface
configurations. 2ts a machining process in which metal is
removed due to cutting action of a revolving
cutter when work is fed past to it. /evolving cutter is held in spindle'arbor work
is clamped on to machine table.
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or!ing principle
ork is rigidly clamped onto table' held b'w centers -ulti;teeth cutter mounted onto spindle. ,utter revolves at fairly high speed work is fed slowly
past the cutter. "s work advances3 cutter;teeth remove the metal from
work surface.
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The Process
%he milling process:%ypically uses a multi;tooth
cutter
ork is fed into the rotatingcutter
,apable of high -//
ell suited for mass
production applications,utting tools for this process
are called milling cutters
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Classifcation o milling process
#eripheral millingp milling
Down -illing
&ace -illing
6nd -illing
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Classifcation o milling process
#eripheral millingp milling
Down -illing
&ace -illing
6nd -illing
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Up"milling (Conventional milling)
#rocess of removing metal by a cutter which is
rotated against the direction of travel of work piece.
,hip thickness is min at beginning of the cut and itreaches to ma! when cut terminates.
,utting force increases from 1ero to ma! per tooth
movement of cutter.
,utting force is directed upwards and tends to liftwork from table.
$urface milled appears to be wavy.
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Up+milling
Down+milling
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Down+milling (Climb milling)E #rocess of removing metal by a cutter which is rotated
in same direction of travel of work piece.
E ,hip thickness is ma! at beginning of the cut and it
reduces to min when cut terminates.
E
,utting force decreases from ma! to min per toothmovement of cutter.
E ,utting force is directed downwards and tends to seat
the work firmly onto the table.
E$urface finish is improved.
E 2t is to be performed only on rigid machines provided
with backlash eliminator.
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2ace MillingE Operation performed by milling
cutter to produce flat surface
perpendicular to a!is of rotation of
cutter.
E #eripheral cutting edge does actual
cutting face cutting edges does
finishing operation.E During one half cutter rotation3
direction of movement of cutter tooth
is opposite to direction of feed
during rest half3 direction reverses.
E ,hip thickness is min in beginning and ma! when work passes
through centre;line of cutter.
E -illed surface contains tooth circular marks.
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1n% MillingE ,ombination of peripheral face milling operation.
E ,utter has teeth both on end face periphery.
E Direction of rotation direction of heli! of cutter should be
same 5 end cutting edges.
E Direction of rotation direction of heli! of cutter should be
opposite 5 peripheral cutting edges.
Milling Machines
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Milling MachinesE ,olumn knee type milling machine.
hand
?ertical ori1ontal'plain
niversal
Omniversal
E &i!ed bed type milling machine. $imple!'plain(having single hori1ontal spindle)
Duple! head(having two hori1ontal spindles)
%riple! head(having < hori1ontal and vertical
spindle)
E #laner type milling machine.E $pecial type milling machine.
/otary table
Drum
#lanetary
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0orizontal67lain Milling Machine
E ?ertical column houses
electrical3 main drive3 spindlesetc mounted onto heavy base.
E Fnee acts as support for
saddle3 worktable other
accessories 5inde!ing head
etc.
E Over arm supports yoke and
free end of arbor.
E"rbor carries cutter which
rotates about hori1ontal a!is.
E %able can move in
longitudinal3 cross vertical
directions.
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*ertical Milling MachineE ?ertical column houses electrical3 main drive
mounted onto heavy base.
E Fnee acts as support for saddle3 worktable other
accessories 5inde!ing head etc.
E Over arm is integral part with column and carries a
housing at its front.
E ousing (ead) can be of fi!ed'swiveling type .
E &i!ed type 5 ead containing spindle is always vertical
and can be ad=usted up down.E $wiveling type 5ead can be swiveled to any desired
angle.
E ,utter is held into spindle which rotates about its a!is.
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Fig. 2 Schematic illustration of milling machines
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Uniersal Milling MachineE $imilar to plain milling machine.
E %able can be swiveled about saddle in hori1ontal
plane.
E ,ircular guide ways are provided on saddle along
which it can be swiveled.
E Over;arm can be pushed back or removed vertical
milling head can replace arbor (?ertical milling
machine).
E
-ost used machine after lathe 3as most of operationscan be performed.
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2i8e% be% tpe plain milling Machine
Simple8
&i!ed bed replaces saddle and knee
and table has only longitudinal
travel only.
pwards3 downwards3 crosswise
movement is restricted. ?ertical column carries parallel
vertical ways on which ad=ustable
spindle head'spindle carrier is
mounted.
$pindle head carries spindle to which arbor is fitted to carry
cutter.
,arrier can be moved up down along the column ways to
ad=ust the tool to work.
3 t t bl Milli M hi
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3otar table Milling MachineE "lso known as continuous milling
machine.
E 2t is used in mass production.
E ,onsists of heavy sturdy
column.
E $pindle carrier mounted on column
carries two vertical spindles each spindle carries a cutter at its
bottom.E $pindle carrier can be moved up down.
E ,onsists of heavy rotating circular table mounted on base.
E &i!tures mounted onto table carries no. of components to be
machined.
E #rocess is continuous.
D t Milli M hi
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Drum tpe Milling MachineE 2t is heavy duty production where two
end faces are machined
simultaneously.
E ,onsists of two vertical columns
mounted on sturdy base.
E eavy drum mounted centrally.
E -illing heads mounted onto columns.E eads carry spindles can be ad=usted
in vertical direction (A;spindles)
E pper < spindles are roughening
cuttersE +ower < spindles are finishing cutters
E &i!tures mounted on periphery of drum
carry =ob.E Drum rotates continuously brining =ob in contact with upper
cutter first finishing cutter latter
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7lain (Slab) Milling
E %o produce flat3 plain3 hori1ontal surface parallel to a!is ofrotation of cutter.
E Operation is carried out on plain machine.
E Depth of cut is ad=usted by rotation of vertical feed screw of
table
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2ace Milling
E %o produce flat3 plain surface parallel to a!is of rotation of cutter.E Operation is carried out in plain machine.
E Depth of cut is ad=usted by rotation of cross feed screw of table
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Si%e6Stra%%le Milling
E %o produce flat vertical surface on the side of work piece using aside milling cutter.
E Depth of cut is ad=usted by rotating vertical feed screw of table.
E hen the machining is re@uired on both sides of work piece3 two
side milling cutter is used mounted on same arbor ($traddle 5
milling)
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4ngular Milling
E%o produce flat surface at an angle3 other than right angle to a!isof revolution of cutter.
E ,utter can be single'double angle cutter depending upon whether
a single surface to be machined or two mutually inclined surfaces
simultaneously.
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:ang MillingE Operation of machining several surfaces of a work piece
simultaneously by feeding table against no. of cutters havingsame'different diameters mounted on a common arbor of
machine.
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1n% MillingE $urfaces produced may be hori1ontal3 vertical or inclined with
respect to top of machine table.E &or hori1ontal surface3 a!is of rotation should be hori1ontal
same for vertical for inclined.
Milli ; 6 6 l t
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Milling ;ewas6grooes6slot
E ses plain milling cutter of
various shapes si1es.E Open slot can be cut by #lain
milling cutter3 side milling
cutter.
E ,losed slot by using end mill.E %;slot'dove tail by using
re@uired shape.
E Fey slot by using end mill or
side mill cutter
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Milling Cutter Characteristics
,utter ,haracteristicsarder than metal being machined
$trong enough to withstand cutting pressures
%ough to resist shock resulting from contact/esist heat and abrasion of cutting
"vailable in various si1es and shapes
Milling cutter
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Milling cuttermaterials.igh carbon steel.$tellite
A.,emented carbides8.,eramics.
Stan%ar% Milling c tters
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Stan%ar% Milling cuttersE 7lain Milling cutter
E uilt+up face
E
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#lain Milling Cutters
Once widely used ,ylinder of high;speed steel with teeth cut
on periphery
sed to produce flat surface $everal types
+ight;duty+ight;duty helical
eavy;dutyigh;heli!
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$ight"Dut% #lain Milling Cutter
+ess than H in. wide3 straight teeth
sed for light milling operations
%hose over H in have heli! angle of
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&eav%"Dut% #lain Milling Cutters
ave fewer teeth than light;duty type#rovide for better chip clearance
eli! angle varies up to A8I
#roduces smoother surface because ofshearing action and reduced chatter
+ess power re@uired
i h li l i illi
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&igh"&eli' #lain MillingCutters
ave heli! angles from A8I to over J9I
$uited to milling of wide and intermittent
surfaces on contour and profile milling$ometimes shank;mounted
with pilot on end and used
for milling elongated slots
St d d Sh ! T & li l
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Standard Shan!"T%pe &elicalMilling Cutters
,alled arbor;type cutters sed for
-illing forms from solid metal/emoving inner sections from solids
2nserted through previously drilled holeand supported at outer end with type "
arbor support
id illi
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Side Milling Cutters
,omparatively narrow cylindrical millingcutters with teeth on each side and onperiphery
sed for cutting slots andfor face and straddle millingoperations
&ree cutting action at high
speeds and feeds $uited for milling deep3
narrow slots
&al"Side Milling
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&al Side MillingCutters sed when only one side of cutter
re@uired
"lso make with interlocking faces so two
cutter may be placed side by side for slotmilling
ave considerable
rake "ble to take heavy
cuts
Milli C
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ace Milling Cutters
0enerally over J in. in diameterave inserted teeth made of high;speed
steel held in place by wedging device
-ost cutting action occursat beveled corners and
periphery of cutter
-akes roughing and
finishing cuts in one pass
A l C
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Angular Cutters
%eeth neither parallel nor perpendicular to
cutting a!is
sed for milling angular surfaces
0rooves3 serrations3 chamfers and reamer teeth Divided into two groups
$ingle;angle milling cutters
Double;angle milling cutters
A l C tt
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Angular Cutters
$ingle;angle%eeth on angular surface-ay or may not have teeth on flat
A8I or J9I Double;angle
%wo intersecting angular surfaceswith cutting teeth on both
6@ual angles on both side of lineat right angle to a!is
d C tt
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ormed Cutters
2ncorporate e!act shape of part to be produced seful for production of small parts 6ach tooth identical in shape
$harpened by grinding tooth face (may havepositive3 1ero or negative rake)2mportant to maintain original rakeDifficult to sharpen
T%pes o ormed
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T%pes o ormedCutters
Concae Cone8 :ear ooth
M t l Slitti S
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Metal"Slitting Sas
Basically thin plain milling cutters with sidesrelieved or KdishedK to prevent rubbing orbinding when used
idths from '>< to >'J in. Operated at appro!imately 'A to 'L of feed
per tooth used for other cutters 4ot advisable to key saw to milling arbor
Backlash eliminator should be engaged
M t l Slitti S
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Metal"Slitting Sas
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Sh ll * d Mill
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Shell *nd Mills
&ace milling cuttersunder J inch
$olid3 multiple;tooth
cutters with teeth onface and periphery
eld on stub arbor
-ay be threaded or usekey in shank to drive
cutter
T Sl t C tt
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T"Slot Cutter
sed to cut wide hori1ontal groove atbottom of %;slot"fter narrow vertical groove machined with
end mill or side milling cutter
,onsists of small side milling cutter withteeth on both sides and integral shank formounting
D t il C tt
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Dovetail Cutter
$imilar to single;angle milling cutter withintegral shank
sed to form sides of dovetail after tongue
or groove machined Obtained with A8I3 89I3 88I3 or J9I angles
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I d i /Di idi H d
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Indexing/Dividing Head
#lain dividing head niversal dividing head
Optical dividing head
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Plain dividing head simple indexing
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2t carries a cast body3 carrying spindle.
&ront end is mounted with carrier center.
/ear end has inde! plate (diff. hole circles on its face teeth on periphery. #late is rotated through worm by handle.
,rank mounted on bolt can be swung to any desired position to bring pin
in front of desired hole.
#lates with > circles of J3A< J9 or 9 >J holes are provided on
heads.
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Dividing head -working
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Dividing head working
$upports the =ob hold it in
position rotates it through adesired angle after each cut is
over.
2nde! crank rotates the =ob
and inde! plate enables this
rotation through desiredangle.
4ormally inde!ing plates
are provided with no. of
circles on each face.
>rown an% Sharpe tpe7late = + $!, $", $?, $#, $9, / holes
7late + $, ', ?, 9, '$, '' holes
7late ' + '?, '9, $, ', ?, 9 holes
Indexing methods
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Indexing methods
Direct;inde!ing #lain or simple inde!ing
,ompound inde!ing
Differential inde!ing "ngular inde!ing
Direct Indexing
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Direct Indexing
2t is simplest case of inde!ing using plain dividing head.
2nde! plate is mounted on spindle rotated by hand. #referably used when no. of divisions to be obtained is a
multiple of no. of slots on periphery of inde! plate.
2nde!ing ratio 4'n
4 4o. of slots on periphery of inde! plate.
n 4o. of divisions re@uired to be obtained.
6!: ,ircumference of =ob is to be divided into J divisions
inde! plate has
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2t is simplest case of inde!ing using plain dividing head'universal
dividing head.
sed when direct method of inde!ing cant be used for obtainingre@uired no. of divisions on work.
%his method involves use of crank3 worm3 wheel and inde! plate.
orm is single start worm wheel has A9 teeth.
$tandard inde!ing plates like Brown $harpe are used.
/ules for inde!ing: 2nde! crank movement A9'4 (4 no. of divisions re@uired)
2f whole no. is obtained3 inde! crank should rotate through a complete no. of
turns obtained.
2f fraction no. is obtained3 numerator denominator of fraction is simplified by
multiplying by a common no. 4ew 4umerator no. of holes to be moved by inde! crank.
4ew Denominator no. of holes in inde! plate circle.
6!: >9 teeth on spur gear 5 2nde! crank movement A9'>9 .'>.'>CP'P.P'
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p gE sed when no. of divisions re@uired is outside the range that cant be
obtained by simple inde!ing.
E
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E 6!: 2nde! J7 divisions
. J7 C>
>
>. >>; 9
A. 9
9
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E #rinciple is similar to that of compound inde!ing.
E ,arried out in < stages:
!" trning the crank a de#ne amont in certain direction$
!" trning index plate and crank %oth& either in same direction or reversedirection$
E -ovement of inde! plate is accomplished by moving plate by means of a train of
gears3 connecting dividing head spindle to worm spindle.
E Differential gears are furnished with change of gears as shown below.
E 4o. of possible teeth:
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' ( no$ o) divisions re*ired
1 ( selected no$ which can %e indexed
E 2n gear ratio obtained3 numerator of fractiondriving gears on
inde! spindle head denominator driven gears on inde! plate.
E 2nde! crank movement A9'"
E 2nde! crank inde! plate should move in same direction or
opposite to each other depending upon gear ratio.
E 2f ";4 is Q3 inde! plate crank rotate in same directionE 2f ";4 is ; 3 inde! plate crank rotate in opposite direction
E $imple gear train ";4 is Q3 : idle gear used
E ,ompound gear train ";4 is Q3 no idle gear used
E $imple gear train ";4 is ; 3
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. 2nde! crank movement A9'L> (#lain inde!ing 5 not possible)
. sing formula: 0./ (L9;L>)CA9'L9 ;>'