capstan & turret lathe

7/26/2019 Capstan & Turret Lathe

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Turret Lathe

Figure 23.9 Schematic illustration of the components of a turret lathe.

Note the two turrets: square and hexagonal (main).


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CAPSTAN AND TURRET LATHE

The standard engine lathe is versatile, but it is not a high production

machine. When production requirements are high, more automatedturning machines must be used.

The turret lathe represents the first step from the engine lathe toward

high production turning machines.

The turret lathe is similar to the engine lathe except that tool-holdingturrets replace the tailstock and the tool post-compound assembly.

The skill of the worker is built into these machines, making it

possible for inexperienced operators to reproduce identical parts.

!n contrast, engine lathe requires a skilled operator and requires more

time to produce parts that are dimensionally the same.

The principal characteristic of turret lathes is that the tools for

consecutive operations are set up for use in the proper sequence.

"lthough skill is required to set and ad#ust the tools properly, once they

are correct, less skill is required to operate the turret lathe.


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he features of a turret lathe that ma!e it a quantit" production

machine are:

ools ma" #e set up in the turret in the proper sequence for theoperation.

$ach station is pro%ided with a feed stop or feed trip so that each cut of

a tool is the same as its pre%ious cut.

&ultiple cuts can #e ta!en from the same station at the same time' such

as two or more turning andor #oring cuts.

Advantages of Turret Lathes


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om#ined cuts can #e made* tools on the cross slide can #e

used at the same time that tools on the turret are cutting.

+igidit" in holding wor! and tools is #uilt into the machine to

permit multiple and com#ined cuts.

urret lathes can also ha%e attachments for taper turning'thread chasing and duplicating' and can #e made.

Advantages of Turret Lathes


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he turret , is mounted on the spindle -' which rests on #earing on the

turret saddle. he index plate 2' the #e%el gear 3 and the indexing ratchet are !e"ed

to the spindle -.

Turretindexing mechanism


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The plunger 14 fitted within the housing and mounted on the saddle locks the

index plate by spring pressure 15 and prevents any rotary movement of the turret

as the tool feeds into the work. A pin 13 fitted on the plunger 14 proects out of the housing. An actuating cam 1! and indexing pawl " are attached to the lathe bed # at the

desired position.



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$oth the cam and the pawl are spring loaded. As the turret reaches the backward position % the actuating cam 1! lifts the

plunger 14 out of the groove in the index plate due to the riding of the pin 13 on

the beveled surface of the cam 1! and thus unlocks the index plate &. The spring loaded pawl " which by this time engages with a groove on the

ratchet plate 4 causes the turret to rotate as the turret head moves backward.



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'hen the index plate or the turret rotates through one sixth of revolution% the

pin 13 and plunger 14 drops out of cam 1! and the plunger locks the index plateat the next groove.

The turret is thus index by one sixth of revolution and again locked into the new

position automatically. The turret holding the next tool is now fed forward and the pawl is released from

the ratchet plate by the spring pressure.



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'hen the index plate or the turret rotates through one sixth of revolution% the

pin 13 and plunger 14 drops out of cam 1! and the plunger locks the index plateat the next groove.

The turret is thus index by one sixth of revolution and again locked into the new

position automatically. The turret holding the next tool is now fed forward and the pawl is released from

the ratchet plate by the spring pressure.



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The ratio of the teeth between the pinion and gear are so chosen that when the

tool mounted on the face of the turret is indexed to bring it to the cutting

position% the particular stop rod for controlling the longitudinal travel of the tool

is aligned with stop 1&.



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The setting of the stop rods ( for limiting the feed of each operation may beadusted by unscrewing the lock nuts and rotating the stop rods on the plate.

Thus six stop rods may be adusted for controlling the longitudinal travel of the

tools mounted on the six faces of the turret.



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he planning for /roduction of a hexagonal #olt is gi%en #elow: he capacit" chart is made a%aila#le. he drawing of the finished hexagonal #olt is ta!en into consideration.

37 mm

10 mm

16 mm

Hexagonal Bolt

he tools and equipments such as #ar stop' roller stead" turning tool holder'

roller stead" #ar ending tool holder' self opening die head' chamfering tool'parting tool are collected.

he drawing of the wor! and tools are superimposed on the capacit" chart to

decide the length of tra%el of the tool and the position of stops.

Production of a hexagonal bolt


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TT 1

T! T3

T "

T6

#$%&H'( T)%%'T

%'A%

*+)A%' T)%%'T

,%$-T

*+)A%' T)%%'T

T1 . Bar sto/ T! . %oller stead box turning tool T3 . Bar ending tool

T . *elf2o/ening die head T" . hamfering tool and T6 . Parting tool

/roper speeds and feeds for each operation are next calculated.



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Setting and machining operation are performed in the following order:

*etting of bar sto/s: he #ar stop is placed on the first turret face. he #ar stop is

set at a distance of 01 mm from the collet face. n extra length of ,1 mm than the

#olt length is allowed' mm for parting off and mm clearance of the collet face sothat the parting off tool ma" penetrate deep into wor! without interference.

*etting of the roller stead box turning tool4he roller stead" #ox turning tool is

set on the next turret face for turning a diameter of , mm. he stop for turning tool

is set 21 mm from the collet face.



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*etting of bar ending tool4he #ar ending tool is set on the next turret face and is

#rought into operation after turning the #ar. he stop is ad4usted in position

accordingl".

*etting of self o/ening die head4he self opening die head is mounted on the

next face of the turret and dies are fitted into it to cut a thread of , mm diameter.

he stop is ad4usted in position !eeping in %iew the pulling out length of the die for

self releasing.



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*etting of chamfering tool4 he chamfering tool is mounted on the four station

turret on the cross slide and the extreme longitudinal position of the saddle is

ad4usted #" a stop. he cross feed mo%ement of the cross slide is also ad4usted #"

a stop.

*etting of /arting off tool4he parting off tool is set on the rear tool post on the

cross slide and longitudinal position of the parting tool is ad4usted #" the stop set at

a distance of mm from the turret face.



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Capstan lathe Vs Turret latheDifference between capstan lathe and turret lathe:

S.No Capstan lathe Turret lathe

1 It is a light duty machine It is a heavy duty machine

2

The tuet head is m!unted !n the

am and the am is m!unted !n thesaddle"

The tuet head is diectly

m!unted !n the saddle andthe saddle slides !ve the #ed$ays

%The saddle $ill n!t #e m!ved duing

machining

The saddle is m!ved al!ng$ith the tuet head duingmachining

& The length$ise m!vement !' tuet isless

The length$ise m!vement !'tuet is m!e


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Srno

Capstan lathe Turret lathe

(Sh!t $!) *ieces !nly can #e machined"

L!ng $!) *ieces can #emachined

+It is easy t! m!ve the tuet head as itslides !ve the am

It is di,cult t! m!ve thetuet head al!ng $ithsaddle

- The tuet head cann!t #e m!vedc!ss$ise

The tuet head can ##em!ved c!ss$ise ins!me tuet lathes

.As the c!nstucti!n !' lathe is n!t igid/heavy cut cann!t #e given

As the c!nstucti!n !'lathe is igid/ heavy cut

can #e given

0It is used '! machining $!) *ieces u* t!+mm diamete

It is used '! machining$!) *ieces u* t!2mm diamete

1 C!llet is used t! h!ld the $!) *iecea$ chuc) is used t!

h!ld the $!) *iece

capstan & turret lathe

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