Note: Descriptions are shown in the official language in which they were submitted.
Description
METHOD AND APPARATUS FOR FORMING AND TENSIONING
A STRAP LOOP ABOUT A PACRAGE
Technical Field
This invention relates to the formation of
a loop of flexible binding or strapping material and
to the subsequent securement of the loop about a
package, article or other object.
Background of the Invention
- 10 Typical machines for binding a package with
a loop of flexible strapping material are described
in the U.S. Patent Nos. 1,357,883; 3,146,694;
3,215,064; 3,636,861; 3,691,939; 3,875,855;
3,916,779; and 3,946,659. These types of machines
incorporate strap guide structures of various kinds
to guide the strap in a loop around the package to be
bound.
Disclosures have been made of machines
which first form a small loop in a certain manner and
which then enlarge the loop to fit around the package
to be bound. In the past, Signode Corporation, the
assignee of the entire interest of the present
invention, has developed several processees and
machines for forming a strap loop about a package,
tensioning the loop, and finally joining the over-
lapping portions of the tensioned loop.
Some of these processees and machines, such
as those disclosed in the U.S. Patent Nos~ 4,062,278,
4,077,313, and 4,079,667, involve the initial forma-
tion of a small, primary strap loop in or around acircular guide and then the subsequent expansion of
the primary loop to a larger diameter for fitting
around the package. The process is then completed
by tensioning the loop about the package, joining
the overlapping strap portions, and severing
~4
.
the secured loop from the trailing portion of the strap.
Described herein are a method and apparatus for first
forming and expanding a strap loop in a novel manner and for
finally securing the strap loop tightly around an article.
The method involves pressing a strap against a guide
surface and then moving the pressed strap in a path against
the guide surface to form a loop. The loop is also expanded
during or after formation of the loop. Then, relative movement
is effected between the expanded loop and the article to
locate the expanded loop about the article. The expanded loop
may, if desired, be subsequently tensioned tightly about the
article. Finally, the adjacent overlapping portions of the
strap loop are joined together by suitable means. If desired,
the trailing portion of the strap may be severed from the loop
before, during, or after the adjacent overlapping strap portions
are joined together.
One embodiment of an apparatus for binding an article
in accordance with the teachings of the present invention in-
cludes a package support table having a horizontal guide surface
against which the free end of a length of thermoplastic strap
may be pressed and moved along to form a small, primary strap
loop.
A rotatable, cantilevered anvil is provided on the guide
surface and is vertically reciprocable with respect to the
guide surface along the axis of anvil rotation. The anvil is
lowered to engage the strap and is then rotated to move the
strap free end in a circle on the guide surface to form a small,
primary strap loop.
The portion of the strap trailing the formed loop is
xestrained against twisting so that the strap necessarily
twists within the primary strap loop thereby forcing the loop
3~
into a plane substantially perpendicular to the guide surface.
After the primary strap loop has been formed, rotation
of the anvil is terminated with a segment of the strap free end
restrained from further movement against the guide surface and
with a leading segment of the strap free end positioned
generally above, and in alignment with, the trailing portion
of the strap located below the edge of the guide surface.
The strap is then fed to expand the primary loop to
a larger, predetermined diameter and a
- 2a -
3~fi;
package is inserted into the expanded loop. ~he
trailing portion of the strap is then pulled to
tighten the loop about the package.
The leading segment of the strap is secured
to an adjacent, underlying portion of the strap loop,
as by forcing the adjacent portion of the strap loop
against the overlying strap leading segment between a
vertically reciprocable, vibrating welding member and
the overlying anvil to effect a friction-fusion weld
of the thermoplastic strap.
The strap is severed with a cutter on the
welding member at the beginning of the welding
sequence as the overlapping strap portions are forced
together between the anvil and welding member. After
the friction-fusion weld has been completed and after
it has cooled, lowering of the welding member permits
the strapped package to be removed from the
apparatus.
Numerous other advantages in features of
the present invention will become readily apparent
from the following detailed description of the
invention and an embodiment thereof, from the claims,
and from the accompanying drawings.
Brief Description of the Drawings
In the accompanying drawings forming part
of the specification, and in which like numerals are
employed to designate like parts throughout the same,
Figures 1-6, taken in ascending numerical
order, diagrammatically illustrate the steps of a
method for binding an article in accordance with the
teachings of the present invention;
Figure 7A is a perspective view of a
preferred embodiment of an apparatus for binding an
article in accordance with the teachings of the
present invention and shows an enlarged strap loop
i'736~:;
formed and ready to receive an article to be bound
with the strap;
Figure 7B is an enlarged, fragmentary,
cross-sectional view of a portion of the apparatus of
Figure 7A illustrating the anvil assenbly;
Figures 8-19 are enlarged, fragmentary,
views of the anvil assembly of the apparatus of
Figure 7A with portions of the apparatus removed to
better illustrate interior detail and the views, when
taken in ascending numerical order, show the sequence
of forming a strap loop and binding a package with
the strap loop;
Figure 20 is a greatly enlarged, perspec-
tive view of the apparatus of Figure 7A with the
lS exterior housing removed to better illustrate the
interior mechanisms;
Figure 21 is an even further enlarged,
perspective, exploded view of some of the mechanisms
illustrated in Figure 20 with some of the mechanism
components omitted for clarity;
Figure 22 is a reduced, fragmentary, plan
view of the apparatus interior mechanisms illustrated
in Figure 20;
Figure 23 is a greatly enlarged,
fragmentary, cross-sectional view taken generally
along the plane 23-23 in Figure 22;
Figure 24 is a greatly enlarged,
fragmentary, cross-sectional view taken generally
along the plane 24-24 in Figure 21;
Figure 25 is an enlarged, fragmentary view
of the top rocker guide and control cam of Figure 24;
Figure 26 is an enlarged, cross-sectional
view of the anvil shaft and rocker member of Figure
24;
Figure 27 is an enlarged, fragmentary,
cross-sectional view of the bottoM rocker guide,
pawl, and control cam taken along the plane 27-27 of
Figure 21;
Figure ~8 is a greatly enlarged,
fragmentary, cross-sectional view taken generally
along the plane 28-28 in Figure 22; and
Figure 29 is a fragmentary, cross-sectional
view taken generally along the planes 29-29 in Figure
28.
Description of the Preferred Embodiment
While this invention is susceptible of
embodiment in many different forms, there is shown in
the drawings and will herein be described in detail
specific embodiments of the method and apparatus for
effecting the teachin~s of the invention, with the
understanding that the present disclosure is to be
considered as an exemplification of the principles of
the invention and is not intended to limit the
invention to the embodiments illustrated.
The precise shapes and sizes of the
components herein described are not essential to the
invention unless otherwise indicated, since the
invention is described with reference to embodiments
which are simple and straightforward.
For ease of description, the apparatus
discussed herein will be described in a normal
operating position and terms such as upper, lower,
horizontal, etc., will be used with reference to this
normal operating position. It will be understood,
however, that the apparatus may be manufactured,
stored, transported and sold in an orientation other
than the normal operating position described.
The apparatus illustrated herein has
certain conventional drive mechanisms and control
mechanisms, the details of which, though not fully
l~t;'~
illustrated or described, will be apparent to those
having skill in the art and an understanding of the
necessary functions of such mechanisms.
PACKAGE BINDING METHOD
A basic method for binding an article or
package with a loop of strap in accordance with the
teachings of the present invention is schematically
illustrated in Figures 1-6. Figure 1 shows a guide
surface 100 defining a slot 102 through which a strap
S passes from beneath the guide surface 100. The
strap may be pulled from a suitable source, such as a
reel of strap, and/or may be fed by suitable strap
feeding means.
An anvil 104 is provided above the guide
surface 100 and is adapted to press a leading portion
of the strap S flat against the guide surface 100.
The anvil 104 is preferably mounted for 360 degree
rotation about a shaft 106. The anvil 104 is rotated
in the direction of arrow 108 on top of the guide
surface 100 thereby moving the leading portion of
strap S in a path while the strap is continuously
pressed against the guide surface 100 to form a
primary strap loop Lp as best illustrated in Figure
2.
It is to be noted from Figure 2 that the
strap S has a flat, band-like configuration with a
first or top surface 110 and a second or bottom
surface 112. As the primary strap loop Lp is
formed, the strap S undergoes a twisting at region T
and the primary loop Lp tends to lift off of the
guide surface 100 and become oriented in a
substantially vertical plane normal to the plane of
the guide surface 100. This phenomenon results from,
among other things, the stiffness of the strap S and
the relatively small diameter of the primary strap
loop Lp.
i'73~
Preferably, as the strap S is moved by anvil 104 to
form the primary strap loop Lp, the trailing portion of the strap
S below the guide surface 100 is restrained from twisting,
relative to the leading strap portion above the guide surface
100 so that the twist T in the strap S occurs between the lead-
ing strap portion pressed by the anvil 104 and a trailing portion
of the strap that is spaced from the pressed or leading strap
portion.
Preferably, rotation of the anvil 104 is terminated so
that a portion of the anvil overhangs the slot 102 as illustrated
in Figure 3. Then, while the strap S is pressed against the
guide surface 100 by the anvil 104, the trailing portion of the
strap S is fed to expand the primary loop Lp to an expanded,
final loop LF that has a predetermined larger size. Then, as
best illustrated in Figure 4, an article, such as package P,
is moved into the expanded loop LF.
If the expanded loop LF is relatively large, the loop
LF may sag, collapse, or fall to one side or the other on top of
the guide surface 100. In this case, the strap S could be
guided or lifted as desired, by hand or otherwise, to provide an
internal loop area of a size and shape suitable for receiving
the package P. However, it is to be realized that, depending
upon the strap thickness, a loop may be expanded to various
larger diameters without collapsing. An expanded loop of rela-
tively thick strap may be self-supporting if it is not too large.
Of course, the package P need not necessarily be moved
into the expanded loop LF. Instead, the guide surface 100, and
any associated mechanisms carrying the guide surface 100 and loop
LF, may be moved to position the loop LF around a stationary
p~ckage P.
6'73~,~
In any case, after relative movement has been effected
between the package P and the expanded loop LF so as to locate
the expanded loop LF
- 7a -
1~i'73~6i
about the package P, the loop LF is then tensioned
about the package P and then sealed in the tensioned
state. Specifically, with reference to Fisure 5, the
strap S is withdrawn, in the direction of dashed
arrow 114, to tighten the loop about the package P.
It is to be noted that anvil 104 only partially
overlies the slot 102 and thus does not force the
leading end segment of the strap S against the
trailing portion of the strap S so as to prevent
withdrawal of the strap S for tensioning the loop
about the package P.
In some situations, as when binding
compressed, resilient materials, the strap S need not
necessarily be withdrawn to tension the loop about
the material. For example, a bale of cotton may be
initially highly compressed by suitable auxiliary
means (not illustrated) and then positioned within
the strap loop LF. Next, the compression on the
bale of cotton can be released so that the bale of
cotton expands against the loop LF. f course, the
trailing portion of the strap S would be restrained
by suitable means to prevent movement of the strap S
in response to the outward expansion force of the
cotton.
In any case, after the strap S is in tight
engagement with the article or package that is being
bound, the leading strap portion and an adjacent
overlapped portion of the strap loop are joined to
secure the loop around the article. There are many
methods for joining overlapping strap loop segments.
If metal strap is used, sealless joints, comprising
interlocking slit deformations of the strap, may be
used. Also, sleeve-type seals may be crimped about
the overlapping segments of metal strap.
If thermoplastic strap is used, a "welded"
1~'73~
joint may be effected by heating the overlapping
segments of the strap. One such method of joining
the overlapping segments of plastic strap, with a
friction-fused weld joint, is illustrated in Figure
6. A weld pad 118 is moved upwardly by a suitable
mechanism 120 in the direction of arrow 122 so as to
force the weld pad 118 against the trailing portion
of the strap S. The trailing portion of the strap S
is forced upwardly against the underside of the
overlapping strap free end which is forced against
the portion of anvil 104 that overhangs the slot
102.
A cutting blade 124 may also be carried
upwardly by mechanism 120 to sever the trailing
portion of the strap S from the loop. Of course, the
trailing portion of the strap S should not be severed
by blade 124 until the overlapping strap segments are
securely pressed between the anvil 104 and the weld
pad 118. To this end, anvil 104 may be normally
biased downwardly (by suitable means not illustrated)
toward guide surface 100 and also have the capability
for being moved upwardly a small amount against the
downward bias. Thus, upward movement of the weld pad
118 would initially press the overlapping strap
segments tightly together against the anvil 104.
Further movement of weld pad 118 and cutter 124
upwardly would overcome the downward bias on the
anvil 104 and force the anvil 104 upwardly (in the
direction of arrow 126 in Figure 6). During this
further upward movement, the trailing portion of the
strap S would be severed by the cutter 124.
In the slightly elevated position, the part
of the strap loop around the bottom of the package P
would no longer be in contact with the guide surface
100. Then, rapid oscillatory movement of the anvil
104 (in the directions of double headed arrow 128 in
73jf~
Figure 6) would cause the strap free end to be moved back and
forth with respect to the stationary underlying portion to
generate heat by friction and effect interface melting there-
between. After holding the overlapping strap segments together
for a pexiod of time sufficient to allow cooling of the weld, the
mechanism 120 lowers the weld pad 118 and cutter 124 to permit
the strapped package P to be removed.
Although the guide surface 100 is illustrated in Figures
1-6 as being generally flat, it is to be realized that the
guide surface 100 need not be flat. It may be curved, undulat-
ing frustoconical, etc. In such a case, the anvil 104 may have
to be provided with a compatible shape and/or drive mechanism
so that the anvil 104 tracks properly on non-flat surface.
Also, during the friction welding step (Figure 6),
the anvil 104 need not be raised off of the guide surface 100.
However, raising the anvil 104 off of the~surface 100 helps to
ensure that the strap will not be heated by friction against the
guide surface 100 and thus helps to ensure that the melting
of the strap material is confined to the interface of the
overlapping strap segments at the weld joint region.
PACKAGE BINDING APPARATUS
A preferred embodiment of an apparatus for binding an
article in accordance with the teachings of the present in-
vention is illustrated in Figures 7A-29. Figure 7A shows the
apparatus 150 in the form of a relatively small countertop unit
adapted for binding articles or packages with a loop of thermo-
plastic flat strap.
As best illustrated in Figure 7A, the apparatus 150
includes a base 152, a package support table 154, a strap reel
housing 156, and a package-actuated cycle switch cover 158.
The table 154 defines a slot 160 through which the strap S
- 1~-
;'7~
passes from the interior of the apparatus to form the strap
loop. The strap S is fed from a supply or source of strap,
such as reel 162 in the housing 156, by mechanisms explained in
detail hereinafter.
The switch cover 158 may be provided with a pair of
spaced-apart ribs 159 on either side of the slot 160. The ribs
159 project outwardly over the table 154 and can function to
provide lateral support to the expanded loop of strap S to
prevent the loop from falling sideways.
Within the table 154, adjacent the cycle switch cover
158, is an anvil assembly 164 (Figure 7A). As best illustrated
in Figures 7B and 8, the anvil assembly 164 includes a rotatable
anvil 204, a vertically reciprocable lift member or feed pad
205, and a vertically reciprocable weld pad 218.
As best illustrated in Figure 8, the anvil 204 has a
disc-like configuration with an outwardly extending lug 222,
the bottom of which lug 222 is serrated to enhance the gripping
action on the top
. ;~
- lOa -
l.~ti'73~f~
surface of the strap S. Mounted to the top of the
anvil 204 is a cover plate 220 which has a generally
circular configuration and,is larger in diameter than
the disc-like anvil 204. The cover plate 220 is
suitably secured, as by welding or gluing, to the
anvil 204. The connected assembly of the cover plate
220 and anvil 204 are secured by means of an allen
head screw 221 to a shaft 400 (Figure 21).
As best illustrated in Figures 7B and 9,
the anvil 204 and cover plate 220 are received on a
guide surface 224 in a cavity defined by a sloping
sidewall 226 in the table 154. When the anvil 204
and cover plate 220 are mounted within the receiving
cavity above guide surface 224, the top surface of
the cover plate 220 is flush with the surface of the
table 154 and serves to support a package placed
thereon. As can be seen with reference to Figure 7B,
there is a space between the circumference of the
cover plate 220 and the sloping sidewall 226 of the
table 154 to accommodate the strap S. 7~
As best illustrated in Figures ~4~ 8 and 9,
the strap S is carried from the strap reel 162 by the
table 154 in a suitable restraining guide or channel
228. The channel 228 opens, as best illustrated in
Figure 7B, in a vertical face 230 adjacent the weld
pad 218.
The weld pad 218 and feed pad 205 are
disposed between the vertical faldce 230 and an opp~sed
vertical face 232. Both the ~eed pad 218 and ~
pad 205 are vertically reciprocable by mechanisms not
visible in Figures 7A-l9.
Figures 8-19, taken sequentially in ascend-
ing numerical order, illustrate in detail the
sequence of operation of the anvil, feed pad, and
weld pad in binding a package P with a loop of strap
S. After discussing the operation sequence, the
~ 3
-12-
mechanisms for effecting the operation of the anvil,
feed pad, and weld pad will be explained in detail
with reference to Figures 20-29.
SEQUENCE OF OPERATION
Before a package is placed on the apparatus
150, the strap S is formed into a relatively small,
primary strap loop and is then expanded into a
larger, final loop of a predetermined size suitable
for receiving the package to be bound. To form the
small, primary strap loop, the strap S is first fed
through ~ channel 228 over the weld pad 218 and feed
pad 205 as illustrated in Figures 8 and 9. During
this step in the sequence, the weld pad 218 and feed
pad 205 are each maintained in a lowered position
below the level of channel 228 and guide surface
224.
After a predetermined length of strap S has
been fed over the feed pad 205, the feed pad 205 is
raised, as illustrated in Figure 10 in the direction
of arrow 234, so as to push a leading segment of the
strap upwardly to the level of the guide surface
224. At the same time, as illustrated in Figure 11,
the anvil 204 is lowered in the direction of arrow
236 and is initially rotated through a predetermined
arc in the direction of arrow 238 thereby engaging
the strap on the feed pad 205 and moving the engaged
portion of the strap off of the feed pad onto the
guide surface 224. Then, as illustrated in
Figure 12, the feed pad 205 is lowered as indicated
by arrow 240.
The anvil 204 is continued to be rotated on
the guide surface 224, as illustrated in Figures
13-15, to twist the strap at T and form the strap S
into a primary loop. During formation of the primary
loop, the strap S is pulled by the anvil 204 from the
~ ;'7~ ~
strap supply (in the direction of arrow~ 242 in Figure 15).
As illustrated in Figure 15, movement of the strap S into a
loop by the anvil 204 causes the strap loop to flex upwardly
away from the guide surface 224.
Although the primary loop can be suitably formed by
the anvil 204 pulling the strap S from a free-wheeling supply
drum or from a slack length of strap, the strap S may also
simultaneously be positively fed forward by a feeding means
(such as the cooperating traction wheels 274 and 276 described
in detail hereinafter with reference to Figures 20 and 21).
The rotation of anvil 204 is terminated, as illustrated
in Figures 7B and 16, with a portion of the anvil lug 222
overlying the guide surface 224 and with a portion of the lug
222 extending outwardly from face 230 over the weld head 218.
In this manner, a leading segment of the strap S is restrained
from movement by being pressed against the guide surface 224
while the trailing portion of the strap S remains unrestrained
below the anvil 204 and above the lowered weld pad 218.
With the strap free end restrained against further
movement by the anvil 204, the trailing portion of the strap S
is fed in the direction of the arrows 243 as illustrated in
Figure 16. This feeding of the strap S expands the primary
strap loop to a larger size. When the strap loop has been
expanded to the size desired, the package P may be inserted
within the loop as illustrated in Figure 17.
A part of the expanded loop extends between the ribs
159 on the switch cover 158 (Figure 7A). If the loop tends
to fall sideways in either direction, a portion of the strap S
will fall against one of the ribs 159. Depending upon the
thickness of the strap S and the diameter of the expanded loop,
- i~
the one rib may then function as a means for preventing the
expanded loop from falling into a completely horizontal plane
on the table 1540 Thus, the loop may "tilt" somewhat from the
vertical, but it will remain sufficiently upright to facilitate
package insertion. If the loop is so large that it nevertheless
falls past the ribs 159 to the completely horizontal position,
the loop can be manually lifted as necessary to facilitate
package insertion.
The package P is properly placed in the loop by pushing
the package into the loop and then back against the cycle
switch cover 158 (Figure 7A) which is movable rearwardly a small
amount. A cycle switch SW is positioned behind the switch
cover 158 (as shown in Figure 18 with the switch cover removed)
and is actuated by the rearward movement of the cover ~1~ 158.
The actuation of the cycle switch SW energi2es the strap
tensioning mechanism (described in detail hereinafter) to with-
draw the trailing portion of the strap S in the direction of
arrow 244, as illustrated in Figure 18, to tension the loop
tightly about the package P.
- 13a -
7~
14-
After the strap S has been drawn tightly
around the package P, the weld pad 218 is moved
upwardly in the direction of arrow 245 (Figure 19) to
press the overlapping loop strap segments between the
weld pad 218 and the anvil 204. The anvil 204 isj~ 5~ac8
preferably spring-biased downwardly toward the ~ ~1
and moves upwardly in response to the upward movement
of the weld pad 218. The anvil 204 may raise the
package upwardly a small amount as the anvil is
forced upwardly. As the weld pad and anvil move
upwardly with the overlapping strap segments pressed
therebetween, a cutter blade 248 (Figures 7B and 19)
severs the trailing portion of the strap from the
strap loop. p~
The weld ~e~*-a44 is raised only a
relatively small amount above the bottom of the strap
guide surface 224--to a height sufficient to enable
the trailing portion of the strap S to be cut by the
cutter blade 248 and to lift the portion of the strap
S below the package P off of the strap guide surface
224. Next, the anvil 204 is oscillated, by a
mechanism to be described in detail hereinafter, to
effect a friction-fusion weld of the strap. With the
particular embodiment of the apparatus described
herein, the feed pad 205 is also raised as the weld
pad is raised. However, the weld pad 218 moves
upwardly a greater amount than the feed pad 205 so
that the overlapping strap segments pressed between
the weld pad 218 and the anvil 204 are clear of the
top of the raised feed pad 205 as well as the bottom
of the cavity 224. Subsequently, both the feed pad
205 and the weld pad 218 are lowered after the
friction-fusion weld has been completed and has
sufficiently cooled.
The anvil 204 is next raised to a slightly
more elevated position by suitable means (described in detail
hereinafter) while the weld pad 218 is lowered so as to provide
adequate clearance for removal of the strapped package from the
apparatus. ThiS further upward movement of the anvil 204 may
lift the package upwardly a slight additional amount.
The novel mechanisms for feeding and tensioning the
strap S, operating the anvil 204, and operating the feed pad
205 and weld pad 218 will next be described in detail with
reference to Figures 20-29.
STRAP FE DING A~D TENSIONING MECHANISM
Figure 20 illustrates the apparatus 150 with the base
152, table 154, and reel housing 156 removed to better show
the in~erior components mounted to a base plate 249. Three
separate motors are provided: a strap feeding and tensioning
motor 250, an anvil rotating and oscillating motor 252, and a
cam drive motor 254.
As best illustrated in Figures 20 and 22, the strap
feeding and tensioning motor 250 is mounted on a plate 256 and
has an output shaft 258 journaled in a vertical support plate
260. The shaft 258 carries a sprocket 262 (Figure 20) around
which is trained a drive chain 264. The drive chain 264 is
also trained around a driven sprocket 266 (Figures 21 and 22)
mounted to a shaft 268 journaled in a support plate 270 (Figures
20 and 21).
On the side of support plate 270 opposite the sprocket
266, the shaft 268 carries another gear 272 and a rotatable,
fixed axis traction wheel or feed wheel 274 (Figure 20) which
rotate with the shaft. Adjacent the fixed-axis feed wheel 274
is a movable traction wheel or feed wheel 276 which is mounted
on and keyed to a shaft 278 that is journaled in a pivotable
support plate 280. The
,~
,, ,~i,;~
- 15 -
3g~ -
-16-
support plate 280 is pivotally mounted through bore
282 (Figure 21) by means of a pin 288 (Figures 20 and
23) to a fixed plate 286.
The shaft 278 of feed wheel 276 carries a
gear 284 for rotation therewith (Figure 20). With
reference to Figure 23, the plate 280 is normally
biased to a first position (to the right by a
suitable spring, not illustrated), in which the gear
284 is engaged with the sprocket 272 associat~d with
feed wheel 274.
Thus, when the gear 284 is engaged with the
gear 272, rotation of the shaft 268 causes rotation
of the gear 272 and hence rotation of the shaft 278.
Both feed wheel 274 and feed wheel 276 are mounted
for rotation with shafts 268 and 278, respectively,
and thus the feed wheels rotate in opposite
directions to frictionally engage and pull the strap
S trained between the two feed wheels. Rotation of
motor 250 in one direction will cause the strap S to
be fed forward into the apparatus while rotation of
the motor 250 in the opposite direction will cause
the strap S to be withdrawn from the apparatus.
The plate 280 can be pivoted to a second
position (to the left in Figure 23), in which the
gear 284 is disengaged from the gear 272. The plate
280 is pivoted to the left by an arm 290 which is
secured to plate 280 by means of screws 292 and 294
and which has, at the opposite end, a roller 296
mounted for rotation about screw 298.
As best illustrated in Figures 20 and 23,
the roller 296 is adapted to be engaged by cam 300
formed on a control cam drum 302 which is mounted for
xotation on a cam shaft 304. Shaft 304 is suitably
journaled in a pair of upstanding support plates 306
;'3~
and 308. When the cam drum 302 rotates cam 300 (by
mechanisms to be described in ~etail hereinafter) to
engage the roller 296 on arm 290, the plate 280 is
pivoted toward the left (as viewed in Figure 23) to
move the feed wheels 274 and 276 apart. Thus, even
through the feed wheel 274 may be continued to be
rotated by motor 250, the strap S would not be
sufficiently frictionally engaged with the feed
wheels to permit continued pulling of the strap S.
The rotating feed wheel 274 would merely slip against
the strap S.
When the cam 300 has rotated past the
roller 296, the plate 280 is urged to the right, as
viewed in Figure 23, by means of the return spring
(not illustrated). The strap S is then pressed in
frictional engagement between the feed wheels and the
gear 284 is re-engaged with gear 272 so that both
feed wheels can rotate together to pull the strap.
CAM DRIVE MECH~NISM
As best illustrated in Figures 20 and 21,
the control cam drum 302 is rotated by means of a cam
drive motor 254. Specifically, motor 254 has an
output sprocket 316 around which is trained a drive
chain 318. Mounted to the cam shaft 304, outboard of
plate 308, is a sprocket 320 around which the chain
318 is also tra3in~ed. Thus, the shaft 304 is driven
through chain ~ by motor 254.
Mounted on shaft 304, between the two
plates 306 and 308, is a switch cam drum 322 which
rotates along with control cam drum 302 on cam shaft
304. The switch cam drum 322 includes a first switch
cam 331, a second switch cam 332 and a third switch
cam 333. Mounted to a base plate 336 are switches
341, 342, and 343, which are associated with, and
~1~j73
-18-
aligned with, the switch cams 331, 332, and 333,
respectively, for actuation thereby. Actuation of
the switches operates the three motors in the proper
sequence.
The first switch 341 is associated with the
anvil rotating and oscillating motor 252, the second
switch 342 operates the cam drive motor 254, and the
third switch 343 operates the strap feeding and
tensioning motor 250. The actuation of the switches
by the switch cam drum 322 and the resulting
operation of the individual motors will be described
in detail hereinafter.
WELD PAD AND FEED PAD ACTUATING MECHANISMS
The mechanisms for raising and lowering the
weld pad 218 and feed pad 205 will next be described
with reference to Figures 7B, 21, and 28. As best
illustrated in Figure 28, weld pad 218 and feed pad
205 are retained behind plate 286 which has an
elongated slot 351 communicating with the weld pad
218 and an elongated slot 353 communicating with the
feed pad 205.
As best illustrated in Figure 21, a pin 355
passes through the slot 351 and is received in the
weld pad 218. Similarly, a pin 357 passes through
the slot 353 and is received in the feed pad 205. As
best illustrated in Figure 28, pin 355 is carried at
the end of a weld pad actuating arm 359 and extends
beyond the arm 359 an amount sufficient to carry a
roller 361 rotatably mounted thereon. Similarly, pin
357 is carried on the end of an L-shaped feed pad
actuating arm 363. The other end of L-shaped arm 363
carries a pin 365 to which is rotatably mounted a
roller 367.
The weld pad actuating arm 359 is pivotably
3~ -
--19--
mounted by means of a pin 369 to the vertical side
plate 286 as best illustrated in Figure 20 and is
spring biased downwardly against the cam drum 302 by
means of a helical compression spring 371.
The feed pad actuating arm 363 is pivotably
mounted to vertical plate 286 by pin 373. Arm 363 is
biased inwardly to hold the roller 367 against the
cam drum 302 by means of a spring 375 mounted in a
spring support block 377 as best illustrated in
Figure 20. The spring support block 377 is secured
to the vertical support plate 286 by ~eans of a screw
379.
As best illustrated in Figure 20 and 21,
the cam drum 302 has a cam 380 for engaging the
roller 367 of the feed pad actuating arm 363.
Similarly, the cam drum 302 has a cam 382 for
engaging the roller 361 on the weld pad actuating arm
359. Rotation of the cam drum 302 by means of the
cam drive motor 254 will thus effect raising and
lowering of the weld pad 218 and feed pad 205 as
necessary during the strapping cycle.
ANYIL OPERATING MECHANISM
The novel mechanism for operating the anvil
204 will next be described in detail with reference
to Figures 21 and 24-28 in particular.
As best illustrated in Figure 21, the anvil
204 is mounted with cover plate 220 to a shaft 400
with screw 221 for rotation with the shaft. The
shaft 400 is vertically oriented in a bore 402 of a
bearing block 404. The shaft 400 is adapted to
rotate about its longitudinal axis and to be
reciprocated vertically along the axis by mechanisms
described in detail hereinafter.
Vertical movement of the shaft 400 and
anvil 204 is effected by the control cam drum 302
'7~
-20-
through a linkage system acting on the bottom of the
shaft 400. Specifically, an anvil lift cam 406 is
positioned below the bottom of the shaft 400. The
cam 406 is pivotally mounted with a pin 410 æ~otl~
to a fixed block 412 (Figure 29). As best illus-
trated in Figure 28, the upper end of the cam 406
carries a pin 414 to which is rotatably mounted a
roller 416. The roller 416 engages the control cam
drum 302 and is adapted to be cammed outwardly by cam
418 on the drum 302. When the roller 416 is moved
outwardly by the cam 418, the anvil lift cam 406
pivots (counterclockwise as viewed in Figure 28)
about pin 410 to lift the anvil shaft 400 and anvil
204 upwardly.
As best illustrated in Figure 21, a helical
coil compression spring 420 is mounted around the
lower end of the shaft 400. The upper end of the
spring 420 is engaged with the underside of the
bearing block 404 and the bottom end of the spring
420 bears against a ring 422 held on the bottom of
the shaft 400 by means of an adjustable retaining nut
424. Thus, the shaft is normally biased downwardly
by spring 420 against the anvil cam 406 to hold the
roller 416 against the control cam drum 302. In this
lowered position, the anvil 204 is held against the
strap lying thereunder (as illustrated in Figure
10). However, rotation of the control cam drum 302,
in response to the control system to be described
hereinafter, will cause cam 418 to engage the cam
roller 416 and lift the anvil shaft 400 and anvil 204
to an elevated position. The force of spring 420 on
shaft 400 can be adjusted by means of the nut 424.
The anvil is rotated with shaft 400 to form
the primary strap loop and is oscillated to form the
friction-fusion weld by means of motor 252 acting
-21-
through a novel mechanism. Specifically, with
reference to Figures 21 and 24, the motor 252 has a
shaft 430 to which is mounted a pulley 432 for
rotation therewith. A toothed drive belt 434 is
trained around pulley 43~ on one end and around a
pulley 436 at the other end. A shaft 438 is mounted
to the pulley 436 for rotation therewith. The shaft
438 rotates within a pair of bearing support blocks
440 and 442 (illustrated in Figure 24 but omitted for
purposes of clarity from Figure 21).
Projecting from the end of shaft 438 is an
offset or eccentric cylindrical shaft 444. Eccentric
shaft 444 carries thereon a roller 446 which is free
to rotate on eccentric shaft 444. The eccentric
shaft 444 and roller 446 are received within an
opening 448 of a rocker member 450.
The rocker member 450 is mounted on the
anvil shaft 400 and includes a one way clutch for
engaging shaft 400. As best illustrated in Figure
~6, the clutch may be of the type that has the form
of a plurality of inwardly facing clutch teeth 452
which trap cylindrically shaped rollers 454 there-
between and wherein the teeth 452 are shaped to allow
the rocker member 450 to rotate freely in one
direction about shaft 400 (clockwise in Figure 26)
but bind the rollers 454 against the shaft 400 when
the rocker member 450 is rotated in the opposite
direction (counterclockwise in Figure 26) thereby
causing the rocker member 450 and the shaft 400 to
rotate together. Such a clutch mechanism is of a
well-known conventional design and further
description or illustration of such a clutch
mechanism is unnecessary.
The rocker member clutch engages and
disengages as necessary during the rotation of the
3i~
-22-
anvil to form the strap loop and during the subse-
~uent friction-fusion welding oscillation of the
anvil. This operation will be explained in detail
after first describing the rocker guide and pawl
mechanisms that cooperate with the rocker member 450
and with the control cam drum 302 to initially rotate
the anvil through a predetermined arc.
As best illustrated in Figures 21, 24, and
25 a top rocker guide 456 is secured to shaft 400 by
means of pin 458 and has an outwardly projecting lug
460 adapted to be engaged by a cam 462 on control cam
drum 302. The ~g 462 is carried on the end face of
control cam drum 302 and thus rotates in a circle
oriented in the vertical plane parallel to the
longitudinal axis of the anvil shaft 400. When the
cam 462 is rotated into engagement with the lug 460,
the shaft 400 and anvil 204 are rotated together
through a predetermined angle as the cam 462 is
carried past the lug 460. This effects the movement
of the strap from the feed pad 205 onto the guide
surface 224 as best illustrated in Figure 11.
A bottom rocker guide 464 is secured to
shaft 400 below the rocker member 450 by means of a
pin 466. As best illustrated in Figure 27, the
bottom rocker guide 464 defines a notch or detent 468
along its outer circumference for receiving and being
engaged by a pawl 470. As best illustrated in Figure
24, the pawl 470 is mounted adjacent the bottom
rocker guide 464 by means of a pin 472 to the bottom
of a lug 474 projecting outwardly from the rocker
member 450.
The end of the pawl 470 opposite the bottom
rocker guide notch 468 defines a bore 476 in which is
received a helical compression spring 478. The
spring 478 extends out of the bore 476 and bears
against the side of the rocker member 450 to bias the
pawl 470 (clockwise as viewed in Figures 24 and 27)
into engagement with the n,otch 4S8 of the bottom
rocker guide 464.
With continued reference to Figures 21, 24
and 27, the control cam drum 302 is seen to include
an additional cam 480 on the end surface thereof for
engaging the distal end of the pawl 470. The cam
480, like cam 462, rotates in a circle in a vertical
plane parallel to the longitudinal axis of the anvil
shaft 400. Thus, rotation of control cam drum 302
will bring cam 480 into engagement with pawl 470 to
thereby disengage the pawl 470 from the notch 468 of
the bottom rocker guide 464.
When the pawl 470 is moved by the control
cam lug 480 to disengage from the notch 468 of the
bottom rocker guide 464, the rocker member 450 is
free to rotate on the anvil shaft 400 in the
clockwise rotation direction as viewed in Figure 24.
In this case, rotation of the eccentric shaft 444
within the rocker member opening 448 will cause
incremental, but uni-directional, rotation of the
anvil shaft 400 about its longitudinal axis. That
is, when the eccentric shaft 444 has rotated to the
position illustrated in Figure 24, the roller 446
carried on the eccentric shaft 444 engages the
left-hand side of the opening 448 of the rocker
member 450. This tends to rotate the rocker member
450 (in the counterclockwise direction as viewed in
Figure 24). However, the clutch rollers 454 are
bound between the rocker member 450 and the anvil
shaft 400 so that the shaft 400 necessarily rotates
counterclockwise with the initial incremental
rotation of the rocker member 450.
As the eccentric shaft 444 continues to
-24-
~otate within the opening 448 of the rocker member
450, the roller 446 on the eccentric shaft 444 begins
to engage the opposite side of the rocker member 450
and thus rotates the rocker member in the opposite
direction. In this direction of rotation, the clutch
rollers 454 are freed and there is no driving of the
anvil shaft 400 in that direction by the rocker
member 450. Consequently, the anvil shaft 400 is
stationary during one half of the rotation cycle of
eccentric shaft 444. The anvil shaft 400 is thus
driven in half cycle increments in only the
counterclockwise direction, as viewed in Figure 24,
to rotate the anvil in a circular arc. This
corresponds to the anvil movement illustrated in
Figures 12-16.
~hen the control cam 302 has rotated to
,~ move the ~ 480 completely past the pawl 470, the
pawl 470 is returned by bias spring 478 back against
the circumference of the bottom rocker guide 464.
However, since the bottom rocker guide 464 turns with
the anvil shaft 400, the pawl 470 does not engage the
notch 468 until the anvil has made a complete
revolution. After anvil has been rotated around to
its original position, pawl 470 re-engages the notch
468 of bottom rocker guide 464.
When the pawl 470 is re-engaged with the
notch 468 on the bottom rocker guide 464, the half
cycle rotation of the rocker member 450 in the
clockwise direction by eccentric shaft 444, as viewed
in Figure 24, will cause the pawl 470 to rotate the
anvil shaft 400 through a small arc in the clockwise
direction. On the other hand, the half cycle
rotation of the rocker member 450 in the counter-
clockwise direction will cause ~he anvil shaft 400 to
rotate through a small arc in the counterclockwise
-25-
direction because of the clutch engagement. In
effect, the rocker member 450 is locked against
movement relative to the shaft 400. Thus, when the
pawl 470 is engaged, rotation of the eccentric shaft
444 within the rocker member opening 448 will cause
the rocker member 450 and anvil shaft 400 to
oscillate about the longitudinal axis of anvil shaft
400. This movement is used during the friction-
fusion weld sequence to join the overlapping strap
segments.
APPARATUS OPERATING SEQUENCE
The sequence of operation of one complete
strapping cycle will next be described. A strapping
sequence begins with an enlarged strap loop having
already been formed just before termination of the
end of the previous cycle. The enlarged strap loop
has the orientation substantially as shown in Figure
7A.
To initiate the strapping cycle, a package
is placed within the enlarged strap loop of the
apparatus 150 (Figure 7A) and against the cycle
switch cover 158. The cycle switch (switch SW in
Figure 18) is actuated by the inward movement of the
cycle switch cover 158.
The cycle switch energizes the strap
feeding and tensioning motor 250 which rotates in the
strap tensioning direction to rotate the pressed-
together strap feed wheels 274 and 276 to tighten the
loop about the package. When the strap has been
pulled to a predetermined tension, the strap feeding
and tensioning motor 250 stalls.
A suitable conventional electrical control
circuit senses the stalling of motor 250 and
energizes the cam drive motor 254 to begin rotation
of the switch cam drum 322 and control cam drum 302
with cam shaft 304. Simultaneously, the strap
feeding and tensioning motor 250 is de-energized and
an electrical brake (not illustrated) associated with
motor 250 is actuated to hold the strap tension
around the package.
The cam drive motor 254 rotates to drive
the cam shaft 304 in the clockwise direction as
viewed in Figure 28. The sequence of the apparatus
operation is effected within a single 360 degree
revolution of the cam shaft 304 as explained in
detail hereinafter.
For discussion purposes, the rotation of
the cam shaft 304 is designated as having a 0 degree
rotation reference position at the beginning of the
last half of the previous strapping cycle. In the
last half of the previous strapping cycle, the cam
shaft 304 had rotated from the 0 degree reference
position to 150 degrees of a complete revolution
during the formation of the new, expanded strap loop
as illustrated in Figure 7A.
With the cam shaft 304 rotated 150 degrees,
wherein the expanded loop is ~eady to receive a
package, the cam shaft 304 is said to be at the "home
position" and the apparatus is ready to begin a new
packaging cycle. When the new package is placed
within the loop to actuate the cam drive motor 254,
the cam shaft 304 begins rotating from the 150 degree
n home position."
As the shaft 304 rotates from the "home
position", the control cam drum 302 and the switch
cam drum 322 both rotate with the shaft. After the
control cam drum 302 has rotated to 160 degrees of
full rotation (i.e., 160 degrees from the reference
position~, the downwardly curved end of cam 380
tFigures 21 and 28) begins to move past the roller
367 on the feed pad actuating arm 363. The actuating
i'73~
-27-
arm spring 375 then rotates the arm 363 about its
pivot pin 373 to raise the feed pad 205 to the
elevated position. ~t 174 degrees of cam shaft
rotation from the reference position, the feed pad
205 is fully elevated. Also at 174 degrees of cam
shaft rotation, the cam 382 begins to engage the
roller 361 for raising the weld pad 218. At 195
degrees of cam shaft rotation from the reference
position, the weld pad 218 has been raised to the
maximum elevation. At this maximum elevation, the
top of the weld pad 218 is higher than the top of the
feed pad 205 and has forced the overlapping strap
segments upwardly against the underside of the anvil
204 as illustrated in Figure 19.
In addition, the upward movement of the
weld pad 218 raises the anvil 204 a slight amount
~against the bias of the compression spring 420 at
the bottom of the anvil shaft 400). The upward
movement of the anvil 204 permits the overlapping
strap segments to be raised off of the strap cavity
guide surface 224. Dur~n~ the upward movement of the
~; weld pad 218 and anvil ~4 together, the cutter blade
248 severs the trailing portion of the strap.
At 195 degrees of cam shaft rotation,
switch 341 is actuated by its associated cam 331
(Figure 20) to energize the anvil rotating and
oscillating motor 252 to weld the loop overlapping
strap segments together. In this welding position,
the pawl 470 is engaged with the bottom rocker guide
notch 468 (Figures 24 and 27) so that the rocker
member 450 is locked to the anvil shaft 400 as a
result of the combined restraints of the pawl and
rocker member clutch. Hence, as explained in detail
above, rotation of the eccentric shaft 444 within the
rocker member 450 by the motor 252 will cause
3 ~6
-28-
oscillation the shaft 400 and the anvil 204 connected
thereto to effect the friction-fwsion weld. As the
weld is being formed, the anvil 204 and weld pad 218
are in the position illustrated generally in Figure
19.
The amplitude of the anvil oscillation is
preferably about l/8th inch and the frequency of the
oscillation is preferably between 5000 and 6~00
Hertz. Under these conditions, the shaft and anvil
are preferably oscillated for about 0.25 seconds to
effect the friction-fùsion weld of the overlapping
strap segments.
As switch cam 331 passes switch 341 at 295
degrees of cam shaft rotation, the switch 341 is
released (i.e., reset) to de-energize the anvil
rotating and oscillating motor 252. Though the anvil
204 is no longer oscillated, the weld pad 218 and
anvil 204 are maintai ~ d in their elevated positions
~ f~ S~.~m~S
with the overlapping ~ps pressed therebetween
while the weld cools. This holding period is
preferably about 0.1 second.
At 315 degrees of cam shaft rotation, the
weld pad 218 is urged downwardly away from the welded
strap. Specifically, cam 382 is carried past the
roller 361 to allow the roller 361 to be urged
inwardly against the cam drum 302 by the spring 371
(Figure 20). This pulls the weld pad 218 downwardly
toward the lowered position. The weld pad reaches
the lowermost position after the control cam drum 302
has rotated 330 degrees from the reference position.
When the weld pad 218 is beginning to move
to the lowered position, at 315 degrees of full cam
shaft rotation, the anvil 204 begins to move further
above the strap guide surface 224. Specifically, cam
418 begins to engage roller 416 and push it
1~i'736~
-29-
outwardly. This causes the anvil lift cam 406 to
pivot upwardly and push the anvil shaft 400
upwardly. This carries the anvil 204 upwardly
(further compressing the shaft spring 420) to provide
even more clearance for removal of the strapped
package. The anvil reaches its maximum elevation
when the cam shaft 304 has rotated 330 degrees from
the reference position.
At 330 degrees of cam shaft rotation, the
feed pad 205 begins to descend. To this end, the cam
380 engages the roller 367 on the feed pad actuating
arm 363 to pivot the arm ~counterclockwise as viewed
in Figure 28) to move the feed pad 205 downwardly.
At 350 degrees of cam shaft rotation, the feed pad
205 has been moved to its downwardmost position.
At 345 degrees of cam shaft rotation, the
switch 342 is actuated by cvn~ol switch cam 332
(Figures 20 and 21) to de-energize the cam drive
motor 254. The motor 254 coasts to a stop with the
cam shaft 304 at 360 degrees of full rotation (i.e.,
back to the initial reference position). At this
point, the strapped package would typically be
removed. However, the package may be removed anytime
after the anvil is raised to its maximum elevation
(330 degrees of cam shaft rotation).
When the strapped package is removed from
the table of the strapping apparatus 150, the cycle
switch cover 158 (Figure 7A) is permitted to be
biased outwardly to its normal position by the cycle
switch (SW Figure 18) and/or suitable bias means as
the internally biased cycle switch resets.
The resetting of the cycle switch re-starts
the cam drive motor 254. This occurs with the cam
shaft at the reference position (0 degrees of full
cam shaft rotation). At 15 degrees of cam shaft
6'7~
-30-
rotation, the switch 343 is actuated by switch cam
333 (Figure 20) to energize the strap feeding and
tensioning motor 250 in the strap feeding direction.
The strap feeding and tensioning motor 250 is
energized through contacts in a conventional
off-delay timer (not illustrated), which contacts are
closed through a suitable relay when switch 343 is
actuated by the cam 333. As explained hereinafter in
detail, the timer later operates to de-energize the
motor 250 at the desired time.
When the motor 250 is energized as
explained above, the feed wheels 274 and 276 rotate
in the directions to feed the strap S forward into
the apparatus as illustrated in Figure 9.
Specifically, with reference to Figure 21, feed wheel
274 is rotated in the clockwise direction as
indicated by arrow 490 while feed wheel 276 is
rotated in the counterclockwise direction as
indicated by arrow 492. It is to be realized that at
this step in the sequence, the pivotally mounted
plate 280, which carries the feed wheel 276 and its
gear 284, is biased (to the right as viewed in
Figures 21 and 23) by a suitable spring (not
illustrated) against the strap S and the adjacent
feed wheel 274.
At 32 degrees of cam shaft rotation,
control cam 380 has passed the roller 367 on the feed
pad actuating arm 363, to allow the spring 375 to
rotate the arm 363 in the clockwise direction as
viewed in Figure 28, to raise the feed pad 205.
Simultaneously, the control cam 300 engages the
roller 296 on arm 290 attached to the pivotally
mounted feed wheel support plate 280. This pivots
plate 280 (to the left as viewed in Figure 23) to
- 35 separate the feed wheel 276 from the feed wheel 274,
-31-
thus terminating the feeding of the strap. The motor
250 continues to run, however.
Downward movement of the anvil 204 is also
initiated at 32 degrees of cam shaft rotation.
Specifically, control cam 418 passes the roller 416
on the anvil lift cam 406. This permits the anvil
shaft 400, under the influence of the spring 420, to
move downwardly. The roller 416 on anvil lift cam
406 is forced inwardly against ~he control cam drum
302 by the spring 420. At 34 degrees of cam shaft
rotation, the anvil 204 has been returned to the
downwardmost position.
At 35 degrees of cam shaft rotation, feed
wheel 276 has been moved to its furthest position
away from feed wheel 274. ~a~
At 44 degrees of cam'rotation, the feed pad
205 has been raised to the maximum elevation as
illustrated in Figure 10.
At 44 degrees of rotation of control cam
drum 302 from the reference position, cam 480
(Figures 24 and 27) on the end face of control cam
drum 302 engages pawl 470. By 79 degrees of cam
shaft rotation, the pawl 470 has been moved to the
extreme disengaged position (illustrated in dashed
lines in Figure 27) to allow the anvil shaft 400 to
rotate in a counterclockwise direction relative to
the rocker member 450.
Also at 79 degrees of cam shaft rotation,
cam 462 on the end face of control cam drum 302
engages lug 460 on the top rocker guide 456 to rotate
the anvil shaft 400 and the anvil 204 mounted thereon
so as to move the strap free end off of the elevated
feed pad 205 and onto the cavity guide surface 224 a~
illustrated in Figures 10 and 11. Figure 10 shows
the initial position of the anvil and feed pad where
;7~
the anvil 204 is in its downwardmost position and the
feed pad 205 is in the elevated position with the
free end of the strap lying on the feed pad 205. In
Figure 11, the anvil 204 has been rotated (by the
control cam 462 acting on the bottom rocker guide 464
to rotate the anvil shaft and anvil) so as to bring
the strap free end onto the cavity guide surface
224.
Additionally, at 79 degrees of cam shaft
rotation, switch cam 331 actuates switch 341 (Figure
20) to energize the anvil rotating and oscillating
motor 252. The eccentric shaft 444 (Figure 24) is
thus rotated within the rocker member 450. As
explained in detail above, oscillation of the rocker
member 450 by the eccentric shaft 444 intermittently
drives, through the rocker member clutch, the shaft
400 (in a clockwise direction as viewed in Figure 24)
to rotate the anvil 204 around the cavity guide
surface 224 as illustrated in Figures 12-16. Since
the strap feed wheel 276 is being held spaced away
from the feed wheel 274, the strap may be pulled as
necessary by the anvil 204 through the apparatus,
from the strap reel 162 while forming the primary
strap loop illustrated in Figure 16.
At 95 degrees of cam shaft rotation, switch
cam 331 has passed switch 341 which then resets to
de-energize the anvil rotating motor 252. The strap
is restrained by the anvil 204 which partially
overhangs the front face 230 (Figure 7B).
At 95 degrees of cam shaft rotation, the
cam 380 on the control cam drum 302 begins to engage
the feed pad actuation arm roller 367 to pivot the
arm 363 (counterclockwise as viewed in Figure 2a) to
move the feed pad 205 toward the lowered position.
Between 79 and 95 degrees of cam shaft
rotation, the control cam 480 on the end of control
~ ~73~
-33~-
cam drum 302 moves past and clears the pawl 470
(Figure 27), thus permitting the pawl return spring
478 to urge the pawl ~70 against the circumference of
the bottom rocker guide 464. However, since the
anvil shaft and bottom rocker guide have been rotated
to carry the notch 468 past the pawl 470, the pawl
does not engage the bottom rocker guide notch 468
until the anvil 204 has been rotated all the way
around to the position illustrated in Figure 16
corresponding to 95 degrees cam shaft rotation.
At 104 degrees of cam shaft rotation,
control cam 300 is positioned such that the roller
296 on arm 290 begins to move inwardly towards the
control cam drum 302 thus permitting the feed wheel
276 to move inwardly (under the influence of a
suitable spring, not illustrated) toward the feed
wheel 274 to press the strap S therebetween. At 112
degrees of cam shaft rotation, the feed wheel 276 has
completed its movement against the feed wheel 274 in
preparation for frictionally engaging the strap S to
feed the strap forward to expand the loop.
Also, at 112 degrees of cam shaft rotation,
the control cam 380 has fully engaged roller 367 to
rotate arm 363 to mcve the feed pad 205 to the
lowermost position.
The motor 250 ~s~ ~till energized and
`~ rotating the feed wheel ~44 in the strap feeding
direction. Consequently, when the feed wheel 276 is
moved back against feed wheel 274 with the strap S
therebetween, the strap S is immediately fed forward
through the apparatus to expand the loop. At this
point, the anvil 204 is still positioned to hold the
overlapping strap free end on the guide surface 224
as illustrated in Figure 16.
The strap feeding motor 250 continues to
~ ~i'736~
-34-
run to feed the strap to enlarge the loop for a
predetermined length of time so as to provide an
enlarged loop of the desired size. This is
determined by the previousl~ discussed off-delay
timer ~not illustrated) which is suitably connected
in the control circuit for motor 250.
It is to be recalled that the off-delay
timer contacts are initially closed to energize the
motor 250. The timer contact closure was effected
through a suitable relay in response to actuation of
the switch 343 by the cam 333 at 15 degrees of cam
shaft rotation. Now, after the formation of the new
primary strap loop, the motor 250 continues to run to
enlarge the strap loop while the cam shaft continues
to rotate.
At 134 degrees of cam shaft rotation, the
cam 333 has passed the switch 343 which then resets.
Resetting of the switch 343 also initiates the timing
sequence of the off-delay timer. The timing sequence
continues to maintain the timer contacts in the motor
circuit closed for a pre-set time period. Thus, the
energization of the motor 250 continues and the strap
loop is further enlarged. At the end of the pre-set
time period, the off-delay timer contacts open to
de-energize the motor 250 and thus terminate the
expansion of the strap loop at ~he desired size.
Also at 134 degrees of cam shaft rotation,
switch cam 332 moves past switch 342 thus resetting
switch 342 and de-energizes the cam drive motor 254.
The cam drive motor 254 coasts to a stop at 150
degrees of cam shaft rotation. At this point, the
cam shaft 304, and the switch cam drum 322 and the
control cam drum 302 carried thereon, are at the home
position. The enlarged strap loop is ready to
receive a new package and the apparatus has the
-35-
appearance as illustrated in Figure 7A. In this
state, the machine is now ready to begin the next
strapping cycle by insertion of the next package into
~he loop and against the cycle switch (as illustrated
in Figures 17 and 18).
From the foregoing, it will be observed
that numerous variations and modifications may be
effected without departing from the true spirit and
scope of the novel concept of the invention. It is
to be understood that no limitation with respect to
the specific apparatus and method illustrated herein
is intended or should be inferred. It is, of course,
intended to cover by the appended claims all such
modifications as fall within the scope of the
claims.
