Pallet locator and clamping assembly

There is disclosed herein improved pallet locating and clamping mechanisms for use in conjunction with the work transfer device in a transfer machine. The pallet locating and clamping means comprise a plurality of inverted V-blocks accurately positioned in the work stations of the machine which are adapted to cooperate with complementary V-grooves provided in the undersides of the pallets for automatically positioning and supporting such pallets precisely in the work stations perparatory to machining or other work operations to be performed on workpieces carried by the pallets. The clamping means for the pallets preferably are mechanically actuated and correlated with the pallet transfer device to clamp the pallets securely on the locating and supporting V-blocks.

BACKGROUND AND SUMMARY OF THE INVENTION 
The present invention is used in association with work transfer devices 
which transfer workpieces carried on pallets progressively 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 securely in the located 
position. Tool heads on the work stations then advance, perform their 
respective operations 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 involve milling, 
drilling or a variety of other operations 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 positioned 
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 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 
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 is often subject to extreme 
adverse environmental operating conditions, it is desirable to avoid 
complex control equipment 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 encountered. 
Accordingly, the present invention provides an economical and efficient 
work transfer machine having extremely durable passive locating means and 
positively acting, mechanically actuated and correlated clamping 
mechanisms which minimizes the need for auxiliary 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 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 engagement with the locators. The 
mechanical linkage is designed so as to insure that the pallets 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 prior to the 
raising of the pallet for transfer to the next successive work station. 
The use of this directly coupled, mechanically actuated clamping mechanism 
eliminates the need for complex and costly control mechanisms and insures 
a reliable sequence correlation between pallet movements and engagement of 
the clamping members. Further, the use of the V-blocks and mating grooves 
on the pallet provides an economical, reliable, and durable means for 
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 of the locating mechanism is 
effectively minimized. 
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.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIG. 1, th 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 is illustrated in FIG. 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 workpiece. 
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 in the bottom of 
the groove 21 which accommodates a bolt such as the one shown at 76 in 
FIG. 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 in 
greater detail with reference to FIG. 3. 
The base 16 also has a vertical 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 
FIG. 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 described in greater detail below with reference to FIGS. 4 and 5. 
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 shown 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 as 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 in FIG. 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 pallet 66 is illustrated as 
being generally square in shape, it may be of any desired shape suitable 
to accommodate the desired workpiece. Further, 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 FIG. 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 threadingly 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 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 operatins which may be performed on the workpiece, metal 
chips, shavings or the like may be 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 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 FIGS. 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 
provided 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 caused to slide to the left with respect to base 
member 12 as seen in FIG. 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 FIG. 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 engagement with a pallet located in the work 
station and to raise the pallet off the supporting and locating V-blocks. 
As seen in FIG. 5, transfer bar 46 is provided with an upwardly extending 
projection 102 which cooperates with 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 projections 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 operation. 
The pallet clamps and associated actuating mechanism are best seen and will 
be described in detail with reference to FIGS. 6, 7, and 8. A clamp 106 is 
shown in FIG. 6 in an operative 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 portion 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 FIG. 1, 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 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 
FIG. 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 26 on 
shaft 60 will then cause rack 64 to move in the direction of arrow 142 of 
FIGS. 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 FIG. 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 insure that slight 
variations between pallets will not result in an insecure clamping action. 
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 associated therewith in an identical manner and 
simultaneously with the actuation of clamps 106 and 58. Thus, once pallet 
66 having a workpiece securely mounted thereon has been transferred into 
the work station and lowered into position 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 FIGS. 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 preferably positioned 
immediately adjacent to V-block 23 so as to position head portion 108 in a 
partially overlying relationship to the V-block 23. This positioning 
allows V-block 23 to directly oppose at least a portion of the force 
exerted 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 respective 
V-blocks 24, 26 108 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 with toggle arms 114 and 120 thereby causing them to 
release and raise clamp 106 out of engagement with pallet 66. As transfer 
bars 46 and 48 are spaced below pallet 66 during the performance of the 
work operation 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 will pallet 
66. 
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 preparation 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 
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 opposite end for removal of the completed workpiece. The transfer 
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 
successive stations mechanically coupled together such as by coupler 148 
of FIG. 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 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 easily 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 embodiment of the invention 
disclosed herein is well calculated to provide the advantages above set 
forth, it will be appreciated that the invention is susceptible to 
modification, variation and change without departing from the fair meaning 
or proper scope of the subjoined claims.