Note: Descriptions are shown in the official language in which they were submitted.
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Back~round and SummarY of the Invention
The present lnvention is used in association with
work transfer de~ices which transfer workpieces carried on
pallets progresslvely from station to station in a transfer
machine and more particularly to improved pallet locating
and clamping mechanisms for use in conjunction with the
transfer device.
In a typical automated transfer machine, workpieces
are mounted securely on individual pallets which are moved
progressively in unison from one work station to another.
Each work station is equipped with means for positioning
or locating a pallet accurately that has been transferred `
into the station and for clamping the located pallet
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securely in the located position. Tool heads on the work
stations then advance, perform their respective operatlons
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
agaln lowe~ed 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
llnes and may be substantially automatic in operation few,
if any, of the work stations will be operator attended. It
iB 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 - -
transfer 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 sub~ect to extreme adverse environmental operating
conditions, it is desirable to avoid complex control equip~
ment as much as possible in the interests of improving
reliability as well as reducing the complexity and time
required for repairs should an equipment failure be encoun-
tered.
Accordingly, the present i.nvention provides an
economical and efficient work transfer machine having
extremely durable passive locating means and positively
acting, mechanically actuated and correlated clamping
mechanisms which minimi~es tne need for auxi;iary control
equipment while insuring a positively acting, durable and
reliable machine requiring a minimum of maintenance. The
work transfer 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 includes 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 station. Clamping members are disposed along two sides
of th~ pallet and are mechanically actuated by and sequence
correlated with the pallet transfer mechanism which raises
and lowets the pallets into and out of engagement with the
locators. ~he mechanical linkage is designed 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 insure that the clamping members are released
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pxior to the rai~sing of the.p~llet fp~ nsfex to the.. neXt
successive work stations. ~he'~se of this di~e.ctly coupled~
mechanically actuatea clamping me~hani~sm eliminates the need
for complex and costly control mechani~sms and ensures a
reliable sequence correlation betwe.çn pallet movements and
engagement of the clamping members. Further, the use of the
V-blocks and mating grooves on the pallet provides an economi-
cal, reliable, and durable means for locating the pallets
which require no moving parts. Also, as the Y-blocks pro~
vide a relatively large surface area of enga,gement with the.
pallets all of wh~ch actively assists in locating the.pallets~
the problems of misalignment of the ~o~kpie.ces caused by ~e~
of the locating mechanism is effectively minim~zed~
In summary of the aboye~ t~e present invent~Qn
provides in a multi-station transfer mach.ine of the type havin~
work carrying pallets, transfer means for-mo.vi~ng the.. pallets
from station to station in the. machine and for lowe~ing and
raising the pallets in the stati~ons, a,nd me.ans. for locating
the pallets precisely vertically and ho~zQnt~lly in the.'
stations, each of the locating me.ans compri:sing, a PluralitY
of spaced, stationary, beveled s.upporting s~urfaces in eac~ of
the stations and a corresponding nu~bq~ of si~i~larlx $p~ced
mating surfaces on each of the pall~tsr the mating surfa,ces of
the pallets being adapted to engage. the stationary beveled
surfaces of the stations when the pallets are ~oved into the
5tations and the stationary b~eyeled surfacçs forming the sole
supporting means for the pallets i`n the stations~ the beveled
and mating surfaces being in such.number and so di-sposed and
arranged that each beveled surface ~n each StatIon acts in
opposition to a plurality of other beveled surfaces in the s~me
station to locate. the pallet on and supported thereby precise-
: ly vertically and also horizontally in at least two dixections~
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Additional adv~nta,ges a,nd fe~tu~es' of thepresent i~nventi~on w~ ecome'appaxent fr~m the following
description of the preferred embodiment taken in conjunction
with the draw~ngs and appended cla~ms,,
BRIEF DESCRIPTION OF ~HE DRAWIN6S
Figure 1 is a top plan view of a work station in
a transfer machine and showing p~llet locating means em~ody-
- ing the present i~nvent~on associated with palle.t clamping
means and a portion of the palle~t tr~nsfer device~ parts
being broken away and shown in s,ectio,n tQ ~llustrate operating
parts of the mechanisms-;
Figure 2 is a bottom plan yiew~ of a pa,llet fo~
', use in conjunction with the pallet lQcators s~own in Figu~e 1;
: Figure 3 is an enlar~e.d~ fragmentaryr side elev~-
tional
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1093494
view of the work station shown in Figure 1 and particularly
illustrating the pallet locating means in operative relation-
ship with the pallet of Figure 2;
Figure 4 is a longitudinal, vertical sectional
view taken on the line 4-4 of Figure 1 and particularly
illustrating the pallet lift mechanism of the transfer
device;
Figure 5 is a transyerse~ vertical sectional view
taken on ehe line 5.5 of Flgure l;
Figure 6 is a transverse, vertical sectional view
taken on the line 6~6 of Figure l;
Figure 7 is an enlarged side elevational view of
the work station with parts broken away to show the --
actuating 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 1, the numeral 10 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 i8 illustrated in Figure 1, a typical transfer
machine has a plurality of work stations and may also
include several idle stations arranged in line along the
length thereof with various work performing apparatus
disposed at the work stations therealong. The specific
number of such stations will depend upon the number of
particular operations to be performed upon a particular
workplece.
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The work station 10 has a base 12 which forms a
support and enclosure for the pallet locating 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 i'n the bottom of the groove 21 which accommodates
a bolt such as the one shown at 76 in Figure 3 for securing
a Y-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 in greater
detail with reference to Pigure 3.
The base 16 also has a Yertical actuator for ~ :
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 centrally disposed longitudinally
extending shaft 32. The rocker arm 30 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 1) 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
. and 5.
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1093494
The base member 12 also has four vertically
extending bores 50, 52, 54 and 56 each of which preferably
is disposed adjacent one of the V~blocks 23-28. A clamping
member 58 is sllown slidably disposed within 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,
A 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 within 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 raise and lower
the clamp members as described in greater detail below.
A pallet adapted 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 a depending peripheral flange
portion 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
in flange portion 68, disposed one on either side of each
of the V-shaped grooves. Holes 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 of 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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pallet 66 is illustrated as belng generally square in
shape, it may be of any desired shape suitable to accommo-
date the desired workpiece. Fur~her7 it may be desirable
to provide additional V-grooves along flange portion 68
thereof should the size of the pallet and weight of the
workpiece require additional support and/or locating
assistance.
The operatiVe relationship of V-block 24 and
V~groove 70 is best seen with reference to Figure 3 in
which there is shown a portion of a base 12 containing a
V-groove 16 with a V-block 24 securely 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 hori~ontal flat surfaces 78 and
80 at the upper and lower diagonally disposed corners thereof
which cooperate with relief grooves 21 and 72 to insure
against debris causing pallet 66 to be inaccurately located
thereon. Each 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, transversely and vertically
within the work station.
In some machining operations which may be performed
on the workpiece, metal chips, shavings or the like may b-:
produced which could fall onto the pallet engaging and
locating surfaces of the V-blocks during transfer of the
pallets and result in inaccurate positioning of successive
pallets thereon. Accordingly, should it be desirable,
V-block 24 may be provided with air passages 81 and 83
communicating with air passage 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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1093494
V-blocks 23, 26 and 28 may be provided with an air supply
in an identical manner,
The vertical actuator is illustrated and will be
described in detail with reference to Figures 4 and 5. As
shown therein, longitudinal shaft 32 is slidably journaled
within the base 12 and has a pair of slots 82 and 84 pro-
vided on opposite sides thereof adjacent one end in which
blocks 86 and 88 respectively are slidably disposed. The
blocks 86 and 88 are pivotally pinned within the slots 82
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 provided on a
mid-portion thereof which engages a pinion portion 100 of
transverse shaft 60 which is also rotatably journaled
within base 12 immediately above shaft 32, As longitudinal
shaft 32 is cau$ed to slide to the left with respect to
base member 12 as seen in Figure 4, rack 98 will 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
actuator's 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-
ment 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 projection 102 which cooperates with
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1~93~94
holes 74 to prevent movement of pallet 66 with respect to
transfer bar 46 during the transfer operation. Similarly,
transfer bar 48 is also provided with projection 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 arranged so
that two of such projections on each transfer bar engage
each pallet during the transfer operationt
The pallet clamps and associated actuating mechan-
ism are best seen and will be described in detail with
reference to Figures 6? 7 and 8~ .A clamp 106 is shown in
Figure 6 in an operatlve relationship to pallet 66 with
transfer bars 46 and 48 shown in a fully lowered position.
The clamp 106 includes a head portion 108 and a generally
cylindrical lower shank portion 110 slidably disposed
within bore 50 provided in base 12, A notched portion 112
is provided in lower shank portlon 110 adjacent the lower
end thereof, A toggle arm 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
portion 118 which communicates with notch 112 and in which
is disposed a second toggle arm 120 pivotally secured to a
cover member 121 by a pin 122. 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 afford access to the clamp actuating mechanism. The
toggle arms 114 and 120 overlap and are pivotally attached
to each other by a pin 124.
As best seen in Figure l? rack 64 is provided with
a laterally inwardly protruding member 126 which has a
longitudinal bore 128 opening outwardly at one end toward
toggle arms 114 and 120 within which is disposed a helical
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coil spring 130 biasing a plunger 132 outwardly from
bore 128. Plunger 132 is adapted to be slidably received
within bore 128 and has a rod portion 134 extending coaxially
through spring 130 and out the opposite 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 20 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. Any 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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1093~94
insure that slight variations bet~een pallets will not
result in an insecure clamping actLon, It should also be
noted that the travel distance for rack 64 and clamp 106
will be designed to insure that rocker arm 30 has fully
lowered pallet 66 onto V-blocks 23, 24, 26.and 28 prior to
the engagement of clamp 106 therewith. Rack 64 has an
identical clamp actuation assembly provided adjacent its
opposite end for actuating clamp 58. Also, transverse
shaft 62 has an identical pinion provided on its opposite
end which actuates two additional clamps disposed in holes
50 and 56 through an identical rack and toggle arms assoc-
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
transferred into the work station and lowered into position
s on the V blocks? the clamps will securely retain the pallet
, in position during the performance of the intended operation
. on the workpiece,
As best seen in Figures 1 and 6~ head portion 108
of clamp 106 has a laterally inwardly extending generally
rectangular-shaped portion 144 having a width substantially
equal to or slightly greater than the width of head portion
108 the bottom edge of which is provided with a shallow
;~ notch 146. The rectangular portion 144 is disposed so as to
overlay the edge of pallet 66 and provides a full face surface
engagement therewith so as to insure that a maximum clamping
; force is exerted on the pallet member.
It should also be noted that the clamp 106 is prefer-
ably pos.Ltioned immediately adjacent to V-block 23 so as to
posltion head portion 108 in a partially overlying relation-
ship to the V-block 23, This positioning allows V-block 23
to directly oppose at least a portion of the force exerted
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1093494
by the clamp 106 thereby insuring that these clamping
forces will not cause distortion of pallet 66. Each of
:` the other three clamps are identical to clamp 106 and are
similarly positioned relative to respectlve V blocks 24,
26 and 28, and further description thereof is believed
unnecessary.
- Once the work operation has been completed, a
power source will 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 will move
'- into engagement wlth 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 the 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 prior 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, projections 102 and 104 will
enter respective holes 74 provided on pallet 66 so as to
prevent movement therebetween. The transfer bars will then
raise pallet 66 up from V-blocks 23, 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 supporting rollers 42 and 44 thereby moving pallet 66
and its associated workpiece into the next work station
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1093494
and the entire cycle is repeated with the transfer bars
being retracted to their original position once the pallets
have been lowered into the next work station.
In a typical installation, a plurality of 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 trans-
fer bars will typically extend the entire length of the
multi-station transfer machine. Further, if desired, a
single power source for the longitudinal shafts 32 may be
provided at one end and the adjacent ends thereof of success-
ive stations mechanically coupled together such as by coupler
14~ 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 totaily
mechanical linkage arrangement which minimizes the need for
auxiliary controls and requires only one or two power sources
at most. Further, as substantially no electrical or electronic
control mechanisms are required in the present invention, less
highly skilled maintenance personnel will be required and any
required adjustments and/or repairs may be made more quickly
and easlly 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 disclosed herein is well calculated toprovide the advantages above set forth, it will be
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appreciated that the invention is susceptible to modifi-
cation, variatlon and change without departing from the
fair meaning or proper scope of the subioined claims.
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