Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
101~ 7
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Th.s Application is a divislon~oS Canad1an ~ppli~
eation Serial No.~ 314?728, Slled October 30, 1978.
Baekground~and Sum~ary of the Invention
The present invention is used in association with
work transfer de~iees which transSer workpieees earried on
pallets progressively from station to station in a transfer
machine and more particularly to improved pallet 10eatin~8
and clamping meehanisms for use in conjunct1on with~the
transfer device.
In a ~typ1eaI automated transSer maeh1ne~ workpiee~es
are mounted securely on lndividual pal1ets which are moved ;~
progressively in unison from one work station to another.
Each work station is equipped with means Sor positioning `~
or loeating a pallet accurately that has been transferred ~ ;`
into the stat~ion and~for clamping the located pallet
i ::.. ~:,: ::
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108~8~
secure:ly in the located positiorl. Tool ~lec1d~ on the work ~ -
stations thetl advance, perEorm thelr respec~lve operatio~s
on the workpiece~ and then retract preparatory to the next
operating cycle of the machine. In practice, after the tool
heads have retracted, the clamps are released and transfer ~ -
bars are engaged with the pallets to lift the latter off ~ -
the positioning or supporting means and then moved to
advance the pallets to the next work station where they are -~
again lowered onto positioning and supporting means and ~;
clamped and other machining operations are performed on the
workpieces.
The machine operations performed on these workpieces
may involved milling, drilling or a variety of other oper-
ations all of which require that each workpiece not only be
securely held in position during the operation so as to avoid ~ ?~
tool breakage but also that successive workpieces be posi~
! tioned in exactly the same location within the work station
so as to insure that the machining operation is accurately
performed on the workpiece. Further, as such work transfer
" ~
machines are generally employed in high volume production -s~ ~
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lines and may be substantially automatic in operation few, ~`~
if any, of the work stations will be operator attended. It
.
is therefore extremely important that the locating and
.~ ~
clamping mechanisms be extremely reliable in operation.
Further, it is also desirable to minimize the moving parts `
and generally simplify the overall construction of such
transEer machines so as to reduce the required maintenance `~
and repair as well as to reduce downtime required to
accomplish the maintenance and/or repair. Also, as -;~
such work transfer equipment
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is often subject to extreme adverse envlronmental operating
conditions, it ls desirable to avold complex control equip-
ment as much as posslble ln the interests of improving
reliability as well as reducing the complexity and time
required for repairs should an equipment failure be
encountered.
Accordingly, the present invention provides posi- ~
tively acting mechanically actuated and correlated clamping ~ -
mechanisms for use in an economical and efficient work trans-
fer machine having extremely durable passive locating means
and which minimizes the need for auxiliary control equipment `~
while insuring a positively acting? durable and reliable ;~
machine requiring a minimum of ma-Lntenance. The work trans~
fer machine of the present invention may include any desired ~;`
number of work stations each of which will include pallet
locator and clamping means as well as means for raising and
lowering workpiece carrying~pallets into position thereon.
The pallet locator means may include a plurality of V-blocks ;`~
secured in position on a supporting base each of which `;
cooperates with mating grooves provided on the pallets to
position the workpiece precisely with respect to the tool
head as the pallet is lowered into the work statlon. The
clamping mechanism includes clamping members which are dis-
posed along two sides of the pallet and are mechanically '
actuated by and sequence correlated with the pallet transfer
mechanism which raises and lowers the pallets into and out of
en&agement with the locators. The mechanical linkage is des-
igned so as to insure that the pallet has been fully lowered ~
:',, :.
prior to engagement of the clamping members with the pallet -~
as well as to lnsure that the clamping members are released
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Prior to the raising of the pallet for trAnsfer to the next
successive work station. The use of this direct]y coupled,
mechanically ac-tuated clamping mechanism eliminates the need
for complex and costly control mechanisms and insures a
reliable sequence correlation be-tween pallet movements and
engagement of the clampin~ members. Further, the use o the -
V-blocks and mating grooves on the pallet provides an econom-
ical, reliable, and durable means or locating the pallets
which require no moving parts. Also, as the V-blocks provide
a relatively large surface area of engagement with the pallets
all of which actively assists in locating the pallets, the
problems of misalignment of the workpieces caused by wear o
the locatiny mechanism is effectively minimized.
The invention according to the parent application
is particularly directed to the aspect of locating the pallets
in the work stations of the machine and in its broadest form
provides a multi~station transfer machine o the type having
work carrying pallets, means for locating the pallets in tlle
stations comprising complemental mating, beveled surfaces in
the stations and on the pallets, each station and each pallet
having a corresponding number of the surfaces and the latter -~
being spaced and arranged and in such number that in use each
pair o mating surfaces in each station acts in opposition
to a plurality of other pairs of mating surfaces in the same `;
station to position the associated pallet precisely vertically
and also horizontally in two directions.
On the other hand the invention according to
the present application is particularly directed to the
aspect of clamping the pallets in the work sta-tions once they
have been located therein, as by the locatin~ means of the
parent application and in its broadest form provides,
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in a palle-t transfer machine of the type having a plurality
of work stations each provided with movable clamping members
engageable with a pallet in said station to hold the same, .
toggle means for moving saicl clamping members into and out of
engagement with said pallets, actuator means for said clamp- :~
ing members, and drive means for transferring motion from
said actuator means to said clamping members, said drive means
including spring operated means disposed adjacent to said
toggle means and being operative by motion of said actuator
10 means in one direction to bring said spring opera~ed means ~
into operative engagement with said toggle means and by ~ ~:
motion of said actuator means in said one direction to extend
said toggle means through said spring operated means to move
said clamping memhers into clamping engagement with said -~ -
pallet.
Additional advantages and features of the present
invention will become apparent from the following description
of the preferred embodiment taken in conjunction with the
drawings and appended claims. ~-
2~ Brief Description of the Drawings .
Figure 1 is a top plan view of a work station ~. .
in a transfer machine and showing pallet locating means - ~:-
associated with pallet clamping means embodying the present
invention and a portion of the pallet transfer device, parts
being broken away and shown in section to illustrate operating
parts of the mechanisms;
Figure 2 is a bottom plan view of a pallet for
use in conjunction with the pallet locators shown in Figure l;
Figure 3 is an enlarged, fragmentary, side -:
elevational
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vlew of the w~rlc ~t~1tlor1 showr1 ln Flg~1re :L an(1 particularly
-lllustrat-lng the pallet locatlng means ln opera1:lve relatlon-
ship with the pelllet of Flg~1re 2;
Flgure 4 ls a longl~udlnal, vertlcal sectional
view taken on the line 4-4 of Figure l and particularly
illustrating the pallet llft mechanism of the transfer
device;
Figure 5 is a transverse~ vertical sectional view
taken on the line 5 5 of Figure li
Figure 6 is a transverse, vertical sectional view
taken on the line 6~6 of Figure l;
~igure 7 is an enldrged side elevational view of
the work station with parts broken away to show the
actuatlng mechanism for the pallet clamps? the latter being
illustrated in the released position; and
Figure 8 is a view similar to Figure 7 but illus-
trating the pallet clamp and its associated actuating
mechanism in the clamped position.
Description of the Preferred Embodiment
Referring now to Figure l, the numeral lO designates
a single representative work station of a transfer machine
embodying the novel features and construction of the present ;~ ~
invention. It should be noted that, while~only a single ,'~ -
work station is illustrated in Figure l, a typical transfer
machine has a plurality of work stations and may also
:Lnclude several id~e stations arranged in line along the -
length thereof wlth various work performing apparatus
disposed at the work stations therealong. The specific
number of such stations will depeDd upon the number of ~ ~ ~
particular operations to be performed upon a particular ~ -
workpiece. ;~
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The work stl~tlon :lO II~EI a baSe l2 whLch for~ns a
support and enclos~lre for the pallet locatlng and clamping
mechanisms, Four generally V-shaped, upwardly opening,
diagonally extending grooves 14, 16, 18 and 20 are formed
in the top of the base 12 at the corners thereof. V-groove,
14 has a small relief groove 21, and an aperture 22 is
provided in the bottom of the groove 21 which accommodates
a bolt such as the one shown at 76 in Figure 3 for securing
a V-block 23 therein. V-grooves 16~ 18 and 20 also have '~
relief grooves 21 and apertures 22 for-the same purpose.
V-blocks 23, 24, 26 and 28 are shaped to substantially '`
correspond to the configuration of the V-grooves 14, 16,
18 and 20. This relationship will be described ln greater `~
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detail with reference to Figure 3. '' -, ;
The base 16 also has a vertical actuator for
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raising and lowering the transfer bars 46 and 48 into and ,~
out of engagement with a pallet supported on the V-blocks ,~
which comprise a rocker arm 30 pivotally attached to the '
base member 12 below a cent`rally disposed longitudinally
extending'shaft 32. The rocker arm 3~0 has a pair of spaced
apart substantially parallel outwardly extending arms 34
and 36, each of which has a relatively deep slot 38 and 40,
respectively, provided therein. A pair of supporting
.~
rollers 42 and 44 are rotatably mounted within respective
slots 38 and 40. The shaft 32 has one end thereof in
pivotable and slidable engagement with the rocker arm 30 '~ ~'
and is adapted to pivot the rocker arm 30 to raise and lower ~-~
a pair of spaced-apart transfer bars 46 and 48 (shown in
phantom in Figure l) which move a pallet vertically into
and out of engagement with the locating blocks 23, 24, 26
. .
and 28. The rocker arm 30 and its operation will be des- ~-
cribed in greater detail below with reference to Figures 4
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and 5.
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The b.l~-3e membcr l2 ~IISo h.ls ~ollr vcrtLcQLLy
extending bore~ 51 52, 5~ alld 5fi each of whLch pr~ferflbly
is disposed ad~acc~llt one of th~ V~blocks 23 28, A clamplng
member 58 i5 shown sLldably dlsposed withln the bore 52 and,
when the work station 10 is in operation, the bores 50, 54
and 56 also have substantially identical clamping members
slidably disposed therein, - -
~ transverse shaft 60 is journaled within base ; ~`
member 12 approximately midway between the longitudinal ends ~;
of work station 10 and is adapted to be rotatably driven by
shaft 32 and described in greater detail below, Transverse
shaft 60 has a pinion gear 62 provided on an end portion
thereof which engages a rack 64 longitudinally slidably
disposed with~n base member 12. Rack 64 is adapted to
engage toggles secured between base member 12, cover
member 121 and clamp member 58 so as to ralse and lower
the clamp members as described in greater detail below. ';
A pa:llet ad~apted for use with transfer machine 10
is illustrated as seen from the bottom side of Figure 2 and
indicated generally at 66. Pallet 66, as shown therein, is
square in shape and has à depending peripheral flange
portlon 68, Four diagonally extending generally V-shaped
grooves 70 are provided in the flange portion 68 at the ~ ;
corners of the pallet 66. Each of these V-shaped grooves ``
has a small rectangular relief groove 72 provided at the ~ `
bottom thereof. A plurality of holes 74 are also provided
i~ flange portion 68, disposed one on either side af each
af the V-shaped grooves. ~oles 74 are of a rather large
diameter, extend only a short distance into flange portion 68
and are adapted to receive upwardly projecting pins provided
on the transfer bars to prevent relative movement af the
pallet with~respect to the transfer bars during transfer of
~ the pallet between work stations. It should be noted that while
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38~
pallet 66 is l:llustrntecl as be:ing generally square in
shape, it may be of any desired shape suLtable to a~comm~-
date the desired workpiece, F~lrther7 it may be desirable
to provide additional V-grooveg along Elange portion 68
thereof should the slze of the pallet and wei~ht of the
workpiece require additional support and/or locating
assistance.
The operatlve relationship of V-block 24 and
V~groove 70 is best seen with reference~to Figure 3 in '~
which there is sho~n a portion of a base 12 containing a
V-groove 16 with a V-block 24 secureiy fastened therein by ;
fastener 76 extending upwardly through hole 22 and thread-
ingly engaging block 24, As illustrated therein, V-block
:
24 has a pair of generally horizontal flat surfaces 78 and - -
80 at the upper and lower diagonally disposed corners thereof
-
which cooperate with rellef grooves 21 and 72 to insure
agalnst debris causing pallet 66~to be inaccurstsly located ; `~
thereon. Rach of the other three diagonally disposed
V-blocks cooperates with respective V-grooves~70 provided
.
in pallet 66 in an identical manner to accurately locate
the workpiece longitudinally, trans~versely and vertically
.: -
within the work station.
In some machining; operations which may be performed `
. :
on the workpiece, metal chips, shavings or the like may be ;~ ,
produced which could f all~onto the pallet engaging and ` ; `
locat:Lng surEaces of ths V-blocks during transfer of the
pallets and result ln inaccurate positioning of successive ;
pallets thereon. Accordingly, should it be desirable,
, V-block 24 may be provided with air passages 81 and 83
communicsting wlth air psssags 85 in support 12 and an air ~`
supply which will allow an air blast to be applied to the ~ ~-
locating surfaces to remove any such debris. The other - -
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V-bl~ck~ 23, 26 and 28 may be provided wlth nn air ~upply
in an identical manner,
The v~rtical ac~uator is :lllustrated and will be
described ln detail wlth reference to Figures 4 and 5. As
shown t7nerein, longitudinal shaft 32 is slidably ~ournaled ::
within the base 12 and has a pair of slots 82 and 84 pro~
vided on opposite sides thereo~ adjacent one end in which
blocks 86 and 88 respectlvely are slidably disposed. The .~ ;
blocks 86 and 88 are pivotally pinned within the slots 82 i
and 84 on rocker arm 30 by pins 90 and 92 respectively.
The rocker arm 30 is also pivotally pinned to the base 12
by pins 94 and 96 at a point below the point of attachment
to shaft 32. The shaft 32 also has a rack 98 provlded on a .
mid-portion thereof which engages a pinion portion 100 oE
transverse shaft oO which is also rotatably journaled .
within base 12 immediatelY above shaft 32, As longitudlnal
shaft 32 is cau$ed to slide to the left with respect to
base member 12 as seen in Figure b, rack 98 wlll impart a
clockwise rotation to pinion 100 and transverse shaft 60. -~
The shaft 32 will also cause the supporting rollers 42 and ~ ;
44, rotatably mounted on the arms 34 and 36 of-the rocker
arm 30, to move upwardly in a counterclockwise direction
from the full line position to the broken line position . -. . ;
illustrated in Figure 4. This motion along with the ..
identical and simultaneous motion of other vertical .
actuators located at each station of the transfer machine
causes transfer bars 46 and 48 which extend the entire
length of the transfer machine to move upwardly into engage~
men-t with a pallet located in the work station and to raise . :~
the pallet off the supporting and locating V-blocks, As ~-
.
seen in Figure 5, transfer bar 46 is provided with an
upwardly extending pFojectlon 102 whlch cooperate5 with
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ho~e~ 74 to prevent movemen~ oE p~llet 66 wLth rc1pect to
transfer bar 46 during ~he tran~fcr operatlon. Simllarly,
transfer bar 48 i9 also provlded with pro~ection 104 for
engaging another hole 74 on pallet 66, Additional projec- ,:
tions are provided on both transfer bars 46 and 48 in a
spaced-apart arrangement and will typically be ~rranged so
that two of such projections on each transfer bar engage
each pallet d~lring the transfer operation, ~
The pallet clamps and associated actûating mechan~ - :
ism are best seen and will be described in detail with
reference to Flgures 6, 7 and 8. A clamp 106 is shown in
Figure 6 in an operative relationship to pallet 66 with ~ -
tran5fer ~ars 46 and 48 shown in a fully lowered position.
The clamp 106 includes a head portion 108 and a generally
cylindrical lower s~ank portion llO slidably disposed
within bore 50 provided in base 12, A notched portion 112;: ~ -
is provided ~n lower shank po~tion 110 adjacent the lower
end thereof, ~ toggle ar~ 114 is pivotally secured to
- : : . ; ~ , : ' ,
shank portion 110 by pin 116 near the lower end of notched -~
portion 112, The base 12 is also provided with a notched
poreion 118 which communicates with notch 112 and~in which
is disposed a second toggle arm 120 pivotaIly secured to a :
.: .
cover member 121 by:a~pin l22. Cover member 121 overlies
and is secured to base 12 in any convenient manner such as
by a plurality of bolts which enable it to be easily removed ~ ::
.~ .
to aEford access to the clamp actuating mechanism, The
toggle ar~s 1l4 and 120 overlap and are pivotally attached
to each other by a pin 124
: ~
As best seen in Figure 1~ rack 64 is provided with
30 a laterally inwardly protruding member 126 which has a
longitudinal bore 128 opening outwardly at one end toward
toggle àrms 114 and 120 within which is disposed a helical
b ~ 10 ~
8~7
coil xpring l30 b:Las:ln~ a p:Lllng~r l32 ou~wartlly from
bore 128. Plunger ].32 :ls adap~e(l to he sl:Ldably recelved
withln bore 128 and llas a rod portion 134 extending coaxially
through spring 130 and out the opposlte end of extension 126.
A stop means 136 is provided on the outer portion of rod 134
so as to prevent spring 130 from ejecting plunger 132 from :
bore 128, Stop means 136 will preferably be in the form of ~;
a nut threadingly engaging the outer end portion of rod 134.
A laterally inwardly extending pin 138 is also secured to -.
rack 64 adjacent its outer terminal end~
When a pallet has been moved into position by ;~
transfer bars 46 and 48, a power source will cause shaft 32
to move in the direction of arrow 140 of Figure 1 which in ~ ~ ~
turn causes rocker arm 30 to lower pallet 66 into position : ;~ .
on the four diagonally disposed V-blocks 23, 24, 26 and 28.
Rocker arm 30 will continue to lower transfer bars 46 and 48 : :
below and out of engagement with pallet 66 to prevent any
possible interference with the positioning of pallet 66 on
the V-blocks 23, 24, 26 and 28, The longitudinal movement
of shaft 32 will also impart a counterclockwise rotation to `
transverse shaft 60 through the cooperation of rack 98 and ~ ,
pinion 100. Pinion 62 on shaft 60 will:then cause rack 64 ~ '
to move in the direction of arrow 142 of Figures 1, 7 and 8
thereby moving plunger 132 into engagement with toggle arms
114 and 120. As rack 64 continues its longitudinal movement,
plunger 132 will cause toggle arms 114 and 120 to pivot about
pins 116, 122 and 124 thereby moving clamp 106 vertically
downward with respect to base 12 and bringing head portion
108 into clamping relationship with pallet 66 as best seen :~
:,,
in Figure 8. ADY over-travel of rack 64 will be absorbed by -~
the retraction of plunger 132 into bore 128 compressing the
helical compression spring~130. This slight over-travel will
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8~3~37
insure tllat sllght var:latlons be~ween pl1Let~ wlll not
result ln an insecure clamping act:Lon. It should al90 be
noted that the travel distance for rack 64 and clamp 106
will be des:lgned to insure that rocker arm 30 has fully
lowered pallet 66 onto V-blocks 23, 2~, 26','and 28 prior to
the engagement oE cl~mp 106 therewith. Kack 64 has an
identical clamp actuation assembly provided adjacent lts
opposite end for actuating clamp 58, Also, transverse
shaft 62 has an identical pinion provided on its opposite '
10 - -end wh'ich actuates two additional clamps disposed in holes , ,
50 and 56 through an identlcal rack and toggle arms ass'oc~
iated therewith in an identical manner and simultaneously
with the actuation of clamps 106 and 58. Thus, one pallet ~ ;
66 having a workpiece securely mounted thereon has been '~
tran:ferred into the work station and lowered lnto position ,-',~
` on the V~block:~ the clamps will ::curely retain the pallet ,'~
in posltion during the performance of the intended operation ,','~
on the workpiece.
' ,As b,est seen in Figures 1 and 6? head portion 108
of clamp 106 has a laterally inwardly extending generally ',~
rectan8ular-shaped portion 144 ha~ing a~width sub:tantially
equal to or slightly greater than the width of head portion
lO8 the bottom edge of which is provlded wi~h a shallow '
notch 146. The rectangular portion 144 i:,'disposed so as ~o ~ ~
overlay the edge of pallet 66 and provides a full face surface ~ -'
engagement ther:with so as to insure~that a maximum clamping
force i9 exerted on the pallet member~
~ It should also be noted that the clamp 106 is prefer~
abiy pos~tioned immedlarely ad~a~cent to V-block 23 so as to ' `~
position head portion 108 in a partially overlying relation-
.. , ... ~
ship to the ~-block 23, This positioning allows V-block 23
to directly oppose at least a portion of the force exerted
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by the c].amp :L06 ther~by :Lnsl~r:lng tha~ these clampln~
force8 wlll not cause ~llstort:Lon of pallet 66. E~ch of :
the other three clamps are lclentlcal to clamp 106 and are
slmllarly posltionecl relatlve to respective V-blocks 24, - ;
26 and 28, and further description thereof ls belleved ~ -
unnecessary. ..
Once the work operation has been completed, a
power source wlll be actuated causing shaft 32 to move
longitudinally in a direction opposite that indicated by
arrow 140 thereby causing the rocker arm 30 to raise
transfer bars 46 and 48 and simultaneously to rotate the ~ ~`
transverse shaft 60 in a clockwise direction to move rack
64 in a direction opposite that indicated by arrow 142. ..
As the rack 64 retracts, pin 138 mounted thereon wlll move
into engagement with toggle arms 114 and 120 thereby :.
causing them to release and raise~clamp 106 out of engage~
ment with pallet 66. As~transfer bars 46 and 48 are spaced
below pallet 66 during the performance:of th~e work opera~
tion and in that only a short travel distance is required
to bring pin 138 into engagement with toggle arms.114 and
120, this mechanical linkage arrangement will insure~that .
the clamps have been released pri~r~to the engagement of
transfer bars 46 and 48 with pallet 46.
As rocker arm 30 raises transfer bars 46 and 48 into :~
engagement with pallet 66, pro~ections 102 and 104 will
. . ..
enter respective holes 74 provided on p.allet 66 so as to
prevent movement therebetween. The transfer bars will then :
raise pallet 66 up from V-blocks 23 9 24, 26 and 28 in pre-
paration for advancement to the next successive work station.
,
A power source will then advance transfer.bars 46 and 48
:
along suppor~ing rollers 42 and 44 thereby moving pallet 66
and~ its associated workpiece into the next work station
.
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1~888~7
and th~ ent-lre cycle is repeate~ wLth the tran~Jf~r bar~
being retracted to their orlgLnal posltlon oncc the pallets
have been lowered lnto the next work 9tat:Lon.
In a typ-lcal in~tallatlon, a plurality oE work
stations will be arranged end to end with a loading station
provided at one end in which a new workpiece and pallet will
be positioned and an unloading station provided at the oppo-
site end for removal of the completed workpiece. The tran9-
fer bars will typically extend the entire length of the
multi-station transfer machine~ Further, lf desired, a
single power source for the longitudinal shafts 32 may be -; ` -
, ,: .. ~:
provided at one end and the adjacent ends thereof oE success-
ive stations mechanically coupled together such as by coupler
148 of Figure 1. Alternatively, the ends of shafts 32 may be
:-~
merely butted together and separate power sources provided at ; ~;`
opposite ends or at intermediate locations as~along the
transfer machine~ In either event, it is apparent that the
transfer machine of the present invention provides a totally
mechanical linkage arrangement which minimizes the need for
auxiliary controls and require9 only one or two power sources ~ `~
at most. Further,~as substantially no electrical or electronic
control mechanisms are required ln the present invention, less
highly skilled maintenance personnel will be required and any ~ i `
~,
required adjuatments and/or repairs may be made-more~quickly
and ea9ily thereby reducing both maintenance costs and machine ~ ;
downtime. Also, the use of direct mechanical linkage insures
- . ~ ;
positive and simultaneous actuation of the entire transfer
machine.
` While it will be apparent that the preferred embodi- - `
ment of the invention dieclosed herein is aell calculated to ~ ;
provide the advaDtages above set ~f orth, it will be ~` `
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appreciated that the Lnvent:lon l.s susc~pt:Lb:L~ to modlfl~
catlon, var:latlon and change wlthout departlng from the
fair meaning or proper scope of the subJolned claims.
`~
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