Note: Descriptions are shown in the official language in which they were submitted.
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1 APPARATUS AND METHOD FOR FORMING TIGHT PACKAGES
TECHNICAL FIELD
The field of this invention generally relates
to packaging systems, and more particularly, relates to
apparatus for forming a tight package from a bag having
a product or substance disposed therein by tying or
applying a closure to the bag in close proximity to the
substance.
BACKGROUND ART
For marketing purposes, it has been found to
be highly desirable to package products, and
particularly produce, in a tight package. ~onsumer
response to a product in a tight package is much more
favorable than to the same quantity of product
contained in a loose package.
Bag tying machines are well known in the art
which include apparatus for forming a throat or neck in
a bag proximate a product in the bag, and apparatus for
applying a closure device, such as a wire, tape or
clip, to the neck to secure the bag in a closed
condition. Such bag typing apparatus often is not
designed to provide for tightening of the bag around
the product or depends upon an initial set-up and
substantially uniform product size to achieve a tight
bag. Typical of such prior art tying machines are the
apparatus of U.S. Patent Nos. 1,738,511, 2,711,278,
2,916,863, 3,919,829, 3,922,834 and 4,291,517.
Manually operable bag tying apparatus have
been devised which will produce tight packages from
bags having product therein. Such bag tying apparatus
are formed to grip the bag near the end, form a throat
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1 or neck in the bag and pull the bag end until the neck
is positioned immediately proximate the product, at
which point a closure device is applied to the bag.
Typical of manual bag tying apparatus which enable the
formation of tight packages are the devices of U.S.
Patent Nos. 2,884,749 and 2,899,785.
Manual bag tying apparatus capable of forming
tight packages, however, have been found to have
several disadvantages which makes automation of the
devices impractical. First, they often require tedious
threading of the bag through a small opening.
Additionally, securement of the bag to enable pulling
of the neck down against the product also is tedious.
Finally, such devices have relied upon the operator's
touch and experience to establish how hard to pull on
the bag.
Automation of bag tying apparatus which
includes a tightening feature has met with limited
success. U.S. Patent No. 4,125,986 to Sheetz discloses
a bagging apparatus with a weighing station, a bag
loading station, a bag transfer station and a bag tying
station. The amount of product to be packaged is
determined by weight. The product is loaded into a bag
which is gripped and suspended by fingers for transfer
to a tying station. As the bag enters the tying
station, the apparatus suspending the bag moves
together to form a neck. The frame of the transfer
station throws a switch, causing the tying machine to
move downward a predetermined distance and then tie the
bag.
The Sheetz apparatus is complex, and the
apparatus for suspending and transferring the filled
bag must be precisely adjusted. The tying operation
occurs after the tying machine moves downward a
predetermined distance toward the product within the
bag; this distance must be adjusted by the operator in
advance. Additionally, the Sheetz apparatus is not
easy to retrofit into existing bagging systems.
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1 U.S. Patent No. 4,446,677 to Kokido discloses
a packaging apparatus for producing a squeezed package.
A predetermined amount of product is loaded into a bag.
When the loading is completed, the weight of the
product within the bag causes the product to narrow
down to a throat above the product. This throat is
positioned between a pair of fixed fingers; the throat
is then further constricted by laterally closing a set
of second fingers. Finally, the typing machine swings
in from the side to apply a tie around the bunched
throat.
The Kokido approach depends on an extremely
complex arrangement of cams, gears and pushrods,
requiring very precise tolerances in both manufacture
and assembly. The relationship between the product in
the bag and the tying machine is fixed; to obtain a
tight package, the precisely correct quantity of
product must be placed in the bag. Because the loading
station and the tying station are integrated into one
apparatus, the apparatus does not lend itself to being
easily retrofitted into existing packaging assemblies.
Also, the apparatus is not self adjusting during the
tying process to accommodate product of varying size,
for example, bundles of carrots of differing lengths.
DISCLOSURE OF INVENTION
This invention overcomes the shortcomings of
previous approaches by providing a bag tying apparatus
which automatically and easily produces tight packages
of product every time.
The apparatus of the present invention
includes a first gripping means formed for tightly and
non-slidably grasping an open bag proximate the mouth
of the bag. A second gripping means is provided which
is formed for grasping the bag loosely and slidably to
form a neck, when the second gripping means is in a
fully closed position, at a position between the first
gripping means and the product in the open bag. A
displacement means is coupled to the first and second
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1 gripping means and formed to move the same with respect
to each other until the second gripping means is
positioned immediately proximate the product within the
bag. With the second gripping means proximate the
product, a closure applying means operates to apply a
- closure to the bag in close proximity to the product,
to create the final, closed, tight package.
The improvement in the bag tying apparatus is
comprised, briefly, of a bag guiding and support
assembly formed for receipt of the bag and product from
a bag loading apparatus and formed for gravity support
of the bag and product in a position in which the upper
end of the bag can be grlpped by the gripping means.
Support of the bag and product on the support portion
automatically causes a plurality of opposed fingers
comprising the gripping means to move to a closed
position for tightly gripping the bag at the open end
and forming a neck in the bag. After the gripping
sequence, the gripping means are vertically displaced
until a predetermined pressure between the bag with the
product inside and the second gripping means is
reached, at which point the bag is closed and then
released to fall free of the apparatus under the
influence of gravity. An anti-jamming structure is
also provided and prohibits the apparatus from
operating if any one of the first gripping means, or
the second gripping means, or the displacement means is
not fully closed or extended to operate as intended.
If this happens, a bag will simply not be tied;
instead, the bag will drop free and can then be tied by
hand.
BRIEF DESCRIPTION OF THE DRAWING
FIGURE 1 is a perspective view of the rear of
an apparatus constructed according to the present
invention with the first and second gripping assemblies
separated in preparation for tying a bag containing a
substance;
FIGURE 2A is a front elevation view of the
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1 first and second gripping assemblies of the apparatus
of Figure 1 at the beginning of a tying sequence;
FIGURE 2B is a top plan view of the first
gripping assembly with the top cover removed and with
the gripping finger shown in solid lines in the open
positions and in broken lines in the closed position;
FIGURE 2C is a top plan view corresponding to
Figure 2B of the second gripping assembly;
FIGURES 3A-3E show front elevation views of
the apparatus of Figure 1 as shown stepping through the
process for forming a tight package according to the
present invention.
BEST MODE OF CARRYING OUT THE INVENTION
The basic elements of the automatic bag tying
apparatus, generally designated 20, of the present
invention can best be understood by reference to
Figures 1 and 3A. Apparatus 20 is designed for use
with bag loading apparatus, now shown, and includes a
first gripping means or assembly 22 formed to tightly
grip bag 46 proximate open end 54. Positioned below
and proximate gripping assembly 22 is a second gripping
assembly 24 which is formed to loosely grip the bag and
form a neck portion 52 between end 54 and the product
or substance 48 positioned in the bag.
In order to form a tight package, bag tying
apparatus 20 also includes displacement means generally
designated 44, which is coupled to one of the gripping
assemblies 22 and 24, here through rod 42 to gripping
assembly 22, and is formed to vertically displace
gripping assembly 22 once bag end 54 has been gripped
and a neck 52 formed in the bag. As gripping assembly
22 is vertically displaced, bag 46 is pulled through
gripping assembly 24 until product 48 in the bag is
urged against gripping assembly 24 to form a tight
package.
The bag tying apparatus further includes a
closure applying means or assembly 56 which is formed
to apply a bag closure to neck 52 immediately above
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1 second gripping means 24 after displacement vertically
to pull the bag tightly down over the product.
The elements of the bag tying apparatus of
the present invention thus far described are broadly
known in the prior art. In the improved apparatus 20,
however, bag guiding and support means, generally
designated 25, is provided which is formed to receive
bag 46 with product 48 therein from a bag loading
machine and guide the same to support plate 38 so that
upper end 54 of bag 46 is positioned for gripping by
the two gripping assemblies.
In order to permit easy and automated loading
of bags into apparatus 20 without the need of tedious
threading of bag ends into gripping mechanisms,
gripping assemblies 22 and 24 are formed for movement
between an open position (Figure 3A), permitting
movement as indicated by arrow 50 of the bag and
product from a bag loading apparatus to support plate
38, and a closed position (Figure 1) at which the bag
is tightly gripped and necked-down by the respective
gripping assemblies 22 and 24. Most preferably,
gripping assemblies 22 and 24 include a plurality of
fingers 30, 32, 34 and 36 that, in the open position,
define axially aligned openings 26 and 28 dimensioned
to receive bag 46 with product 48 therethrough.
Openings 26 and 28 are further axially aligned with a
funnel and depending sleeve structure 170 in guiding
and support assembly 25. Thus, it is relatively simple
to drop bag 46 through openings 26 and 28 and into
funnel 170 which centers the bag in openings 26 and 28
for gripping by the gripping assemblies and assures
support of the bag and substance on support plate 38.
Automatic actuation of gripping assemblies 22
and 24 occurs when the bag and product rest on plate 38
which is downwaxdly displaced and changes the state of
switch 40 so as to power the gripping assemblies and
cause movement of fingers 30, 32, 34 and 36 to the
closed gripping position in a manner which will be more
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1 fully described hereinafter. Switch 40 also commences
a timing cycle, which can be interrupted by a limit
switch if various events are not completed, including
vertical displacement of first gripping assembly 22 by
displacement means 44.
Instead of attempting to pre-set a
displacement means 44 includes pressure sensing means
182 which is formed to sense the pressure between
gripping assembly 24 and substance 48 as the bag is
necked down against the substance. When the pressure
sensed by guage 182 reaches a predetermined known
level, which can be adjusted in accordance with the bag
material and thickness, further displacement of first
gripping means 22 is terminated. Thus, variations in
length of product 48 are automatically accounted for,
and tying apparatus 20 will pull the bag end up until
the resistance to further displacement presented by the
substance inside the bag reaches a desired level.
Upon attainment o~ the pre-set pressure,
closure assembly 56 also is automatically actuated. As
shown in the drawing, assembly 56 is a tape applying
device which swings from a retracted position, shown in
Figures 1 and 3A, to a tape applying position, shown in
Figures 3D and 3E. Such closure applying assemblies
are well known in the art and can take the form of
wire, clip or strand applying apparatus.
In operation, therefore, Figures 3A-3E show
one cycle of forming a tight package using automatic
bag tying apparatus 20. Figure 3A shows that an
initially unclosed or unsealed bag 46, loosely holding
a substance 48, is dropped vertically as indicated by
an arrow 50 from bag loading means (not shown) through
openings 26 and 28. At this point, fingers 30, 32, 34
and 36 are positioned at the periphery of openings 26
and 28. Unsealed bag 46 hits pressure plate 38 while a
bag neck 52 and an open bag mouth 54 are in the
vicinity of the fingers. In response to bag impact,
pressure plate 38 contacts and activates switch 40 to
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1 cause cycling of apparatus 20.
Figure 3B shows that fingers 30 and 32 move
together tightly to clamp the bag proximate mouth 54
with enough binding force to hold unsealed bag 46
suspended as pressure plate 38 pivots away to a
retracted position. Simultaneously, fingers 34 and 36
move toward one another but do not come completely
together; they instead stop short of contact to leave a
gap between one another.
In Figure 3C, upper assembly 22 moves
vertically away from lower assembly 24 until substance
48 exerts a predetermined amount of pressure against
lower fingers 34 and 36. When this predetermined
pressure is reached, cylinder 44 stops moving upper
assembly 22. The bag is now tightly stretched over
product 48, and neck 52 extends down to just above the
product.
Figure 3D shows that a pivotally mounted
tying machine 56 swings in from the side to a position
between assemblies 22 and 24, to wrap a tying device,
such as a tape 62, a plastic clip or metal wire, around
throat 52 immediately adjacent lower fingers 34 and 36.
This has the effect of forming a tight package 60
because the tying machine seals throat 52 immediately
adjacent substance 48 within the bag. Since the bag
will most usually be formed of a resilient material,
the tying of the bag above fingers 34 and 36 will be
compensated by resilient contraction of the bag and
vertical displacement of bag closure 62 toward
substance 48. Selection of the pressure level at which
displacement is terminated will be based in part on
such resilient contraction after release of the tied
bag.
In Figure 3E, tight package 60 is released by
moving apart upper fingers 30 and 32. Tight package 60
drops free under the influence of gravity. Lower
fingers 34 and 36 may be moved apart at the time of
opening of fingers 30 and 32 or thereafter to resume
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1 their starting positions, and tying machine 56 may also
pivot away from assemblies 22 and 24 at the time of
release of the upper fingers. After release of package
60, cylinder 44 lowers upper assembly 22 back down into
contact with lower assembly 24, and pressure plate 38
pivots back into coaxial alignment with assemblies 22
and 24. With apparatus 20 back to the position shown
in Figure 3A, one cycle is complete and another cycle
can be started.
Figures 2A-2C show additional structural
details of gripping assemblies 22 and 24. Figure 2A
shows schematically that which is shown with
particularity in the top views of Figures 2B and 2C.
The assemblies are in contact with one another along a
respective upper face 64 and a lower face 66.
Figures 2A, 2B and 2C show elongated fingers
30 and 32 retracted to an open position proximate the
periphery of opening 26 in assembly plate 27. In
addition to this first pair of opposed fingers 30 and
32, assembly 22 preferably includes a second pair of
opposed elongated fingers 68 and 70. Fingers 30 and 32
each carry a respective guide bar 72 and 74 attached in
spaced apart relation to fingers 30 and 32 by bolts or
screws 76, to create a space for receiving fingers 68
and 70. Guide bars 72 and 74 insure that the proper
relation is maintained among all four fingers 30, 32,
68 and 70 during pivotal movement of the fingers.
Finger 70 is not visible in Figure 2A because it lies
directly behind fingers 68 and is obscured by it. It
also can be seen that lower assembly 24, in addition to
a pair of opposed elongated fingers 34 and 36, has
another second set of fingers 78 and 80.
In order to simultaneously move the fingers
together for gripping of bag 46, the fingers are
preferably mounted for pivotal movement to a plurality
of sprockets. Thus, finger 68 is pivotally carried by
a sprocket 82 mounted to turn within upper assembly 22.
Sprocket 82 is driven by an arm 84 through pin 86 and
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1 piston shaft 88. It is preferable that the drive means
for the gripping assemblies be pneumatic and that shaft
88 extend to a piston carried within a pneumatic upper
cylinder 90 coupled to extend away from a side of the
first gripping assembly 22.
Within upper assembly 22, the remainder of
fingers 30, 70 and 76 are mounted in an identical
fashion as finger 68 to sprockets. Thus, finger 30 is
pivotally carried by a sprocket 98, finger 70 pivots
about a sprocket 100, and finger 32 moves on a sprocket
102. To effect simultaneous pivoting operation of the
fingers, a chain 103 mechanically connects sprockets
82, 98, 100 and 102.
Fingers 2B and 2C show with solid lines the
fingers 68, 30, 70 and 32 at their open position
ad;acent the sides of upper assembly 22 and the
periphery of opening 26. The broken lines show the
respective fingers when in the fully closed position,
as designated by fingers 68A, 30A, 70A and 32A. By
energizing cylinder 90, shaft 88 moves in the direction
indicated by an arrow 104, causing arm 84 to move in
the same direction away from cylinder 90. Arm 84
pivots sprocket 82 causing finger 68 to pivot inward to
assume the position indicated by dashed finger 68A. By
pivoting, sprocket 82 moves chain 102, which in turn
pivots sprockets 98, 100 and 102 to cause the remaining
fingers to pivot inwardly across opening 26 to assume
the position indicated by fingers 30A, 70A and 32A.
When in the fully closed position, fingers 68, 30, 70
and 32 engage and overlap one another in a contact
region 106.
The construction of fingers 78, 34, 80 and 36
within second gripping assembly 24 is substantially
identical to that of the fingers within first gripping
assembly 22; therefore, lower assembly 24 is described
in a somewhat abbreviated fashion. Fingers 78, 34, 80
and 36 are carried to pivot on respective sprockets
108, 110, 112 and 114. When pivoted to a fully closed
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1 position at a contact region 116, the fingers assume
the orientations shown in phantom as fingers 78A, 34A,
80A and 36A. At the fully closed position within
contact region 116, the fingers leave a gap 118
dimensioned to loosely confine, but not tightly grip,
bag 46.
The second set of sprockets are mechanically
coupled together by chain 120, and sprocket 108 is
connected by arm 122 piston shaft 126 which extends
from pneumatic cylinder 128. When cylinder 128 is
energized, the combined movement of shaft 126, arm 122,
sprockets 108, 110, 112, 114 and chain 120 causes
resting arms 78, 34, 24 and 36 to pivot and move across
opening 28, to assume the fully closed position
indicated by phantom lines as fingers 78A, 34A, 80A and
36A.
Referring now to Figure 1, it will be seen
that apparatus 20 includes a frame 136 for supporting
the various parts when assembled. Frame 136 includes a
group of legs 138, 140, 142 and 144. Figures 3A-3E
show frame 136 supported on a floor 146 suspended above
an opening 148 in floor 146. Opening 148 indicates
schematically that tight package 60 is provided enough
room beneath frame 136 to drop free under the influence
of gravity for transport away from apparatus 20.
Tying machine 56 is carried by an arm 150
pivotally connected with a pin 152 which is coupled to
a flange 154 extending from frame leg 138. A portion
156 of arm 150 extends beyond flange 154 and is
pivotally coupled to piston rod 160 extending outwardly
from pneumatic cylinder 162. This cylinder, as with
all the other pneumatic cylinders used with package
forming apparatus 20, is coupled by conventional means
to a compressed air source (not shown), and its
operation is sequenced by controller 188 using
conventional pneumatic logic circuitry. Tying machine
56 in this preferred embodiment is a conventional
machine having a slot 164 through which neck 52 slides
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1 en route to a central opening 166 where a strip of tape
150 (Figure 3A) is securely wrapped around neck 52 to
close bag 46.
Two structures are provided on apparatus 20
for guiding unsealed bag 46, now holding substance 48,
as it enters bag tying apparatus 20. Upper opening 26
of first gripping assembly 22 preferably carries a
flexible disk-like guide 168, formed by cutting lines
radially from the center of a flexible material, such
as plastic or ~ubber, out toward the circumference of
the material. Because the resulting pie shaped
sections of guide 168 are not joined at their center,
but are continuously joined at their circumference,
guide 168 can be fitted into upper opening 126 without
impeding the downward passage of bag 46. Guide 168 has
the effect of centering and loosely gathering bag 46 to
create the somewhat restricted neck 52 to improve the
handling characteristics of the bag.
Mounted in lower assembly 24 is a conically
shaped chute 170 having a wide mouth positioned
adjacent lower opening 28, and tapering inwardly toward
a narrower mouth 172 which stops above pressur~ plate
38. Chute 170 centers bag 46 as it passes through
upper opening 26 and lower opening 28.
Figures 3A-3E schematically show that lower
assembly 24 is immovably secured within frame 136.
However, upper assembly 22 is free to move vertically
up and down within frame 136, as indicated
schematically by a pair of wheels 174 and 176 mounted
to roll on guides 178 and 180. In fact, wheels 174 and
176 are not exposed as shown in Figure 3A. Instead,
they are carried within respective extension portions
184 and 186 of legs 140 and 138. As previously
mentioned, upper assembly 22 is coupled by rod 42 to be
carried by a piston (not visible) carried within
pneumatic cylinder 44.
Support plate 38 is securely coupled to a
shaft 190. This shaft is pivotally mounted within a
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1 collar 192 secure to lower assembly 24 and a collar 194
attached to upper frame member 191. In order to enable
retraction of plate 38 for gravitation of bags from the
tying apparatus, pneumatic cylinder 196 is provided
which has a piston rod 198 coupled to a lever arm 193
extending from shaft 190. Pneumatic cylinder 196 can
pull rod 198 back and forth, causing shaft 190 to
pivot, and therefore pressure plate 38 to pivot into
and out of alignment beneath openings 26 and 28 and
guide funnel 170.
OPERATION
Figures 1 and 3A-3E can be used in describing
the details of operation which were broadly covered
above. Initially, upper assembly 22 and lower assembly
24 are in contact with each other as shown in Figure
3A. All fingers are in the initially open position
shown in Figures 2A, 28 and 2C, withdrawn against the
sides of assemblies 22 and 24 and positioned at the
periphery of openings 26 and 28.
An unclosed bag 46 is dropped through or
otherwise introduced from a bag loading apparatus or by
hand into guide 168 mounted in opening 26. Unsealed
bag 46 continues its downward journey to encounter
chute 170 to be generally centered within openings 26
and 28 at the time of impact with pressure plate 38.
When hit by bag 46, plate 38 moves downward
slightly, as shown in Figure 3A, to strike switch 40;
this begins the cycle for forming a closed tight
package. The sets of fingers carried in assemblies 22
and 24 move into openings 26 and 28. At their fully
closed position, the first pair of opposed fingers 30
and 32 slightly overlap to firmly grip that portion of
bag neck 52 residing within contact region 106 shown in
Figure 2B. At least one and preferably several of
teeth or serrations 200 are carried on the biting edge
of the fingers to improve the grip exerted on the upper
end of the bag.
Likewise, cylinder 128 moves the sprockets
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1 and chain of lower assembly ~4 to move fingers 70, 34,
80 and 36 into contact region 116 shown in Figure 2C.
The fingers in the lower assembly, however, do not come
into contact with one another in their fully closed
position. Instead, they are separated by gap 118
having a small square cross-sectional area. Gap 118
exists so that portion of neck 52 within gap 118
remains gathered but can slip with respect to the
second gripping assembly.
As shown in Figure 3B, pressure plate 38
pivots away from apparatus 20 to leave unsealed bag 46
suspended by the pinching action of the fingers in the
first bag gripping assembly. As shown in Figure 3C,
cylinder 44 pulls assembly 22 upward vertically away
from lower assembly 24, moving unsealed bag 46 and
substance 48 with it. Substance 48 encounters the
fingers within lower assembly 24 and resists further
upward movement of assembly 22. This resistance causes
a building of pressure within cylinder 44. When a
predetermined and pre-set pressure maximum has been
reached, guage 182 senses this and stops further upward
displacement of gripping assembly 22.
As shown in Figure 3C, substance 48 now
presses firmly against the lower fingers 34 and 36,
neck 52 is pulled taut, and the upper and lower
assemblies 22 and 24 are separated from one another.
If at this point in the cycle any of the fingers have
not assumed their fully closed position, or assemblies
22 and 24 have not separated to be fully extended as
desired, the tying procedure is interrupted. Limit
switches (not visible) carried within assemblies 22 and
24 are thrown as the fingers move, and as the upper and
lower assemblies separate at least to a minimum amount.
If the limit switches are not thrown, the bag tying
procedure is interrupted, the fingers open, and untied
bag 46 drops downward and free of apparatus 20. This
anti-jamming feature stops tying machine ~6 from tying
the bag when it is not properly gripped and distended.
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1 In the event of interrupted operation, the bag drops
free and may be tied by hand.
If everything has gone as intended at this
point, tying machine 56 is pivoted by cylinder 162 and
rod 60 to swing into the tying position ~hown in Figure
3D, where it ties the bag immediately above and
adjacent ~ingers 34 and 36. Because fingers 34 and 36
rest against substance 48, the bag is tied as close to
substance 48 as possible. While tying machine 56 is
still centered between openings 26 and 28, the fingers
separate and the now tight package 60 drops. All the
equipment returns to the starting position shown in
Figure 3A, with tying machine 56 off to the side,
pressure plate 38 beneath assemblies 22 and 24, and
assemblies 22 and 24 in contact with one another with
all fingers retracted ~rom openings 26 and 28. A new
tying cycle can now proceed.
