Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
In the past, Signode Corporation, the assignee
of the entire interest of the present invention, has
developed several methods and machines for forming a strap
".
-~ loop aibout a package, tensioning the loop, and joining tihe
overlapping portions of the tensioned loop by friction-fusion
or other means. Such methods and apparatuses are typified
by those disclosed and claimed in the U.S. patent to Sten-
saker et al., No. 3,442,732S to Vilcins, No. 3,442,733~ to
Ericsson, No. 3,442,734s to Stensaker, No. 3,442,735~ to
Kobiella, No. 3,442,203; and to Ericsson, No. 3,58~572.
Some strapping machines, such as the machine
disclosed in the Kobiella U.S. Patent No. 3,442,203, are
of the completely automatic type, i.e., one which automa-
tlcally feeds a thermoplastic strap around a package from
a strsp supply source, grips the leading end of the strap,
!
; withdraws the standing length of the strap to tension the
strap loop, friction-fuses the overlapping portions of the
loop, and severs the loop from the standing length of the
strap. However, this type of automatic strapping machine
has a relatively large, ring-like, rigid chute into which
the package is inserted and in which the strap is fed to
form a closed loop around the package. With therimoplastic
strap, problems have been encountered wherein the strap may
buckle or ~am in the chute as the strap is fed around the
package. ~his is due to the relatively low column strength
of the thermoplastic strap. In addition, a ring-like chute
adds considerable bulk to the machine and requires a work
;~ space, or operating space, large enough to accommodate the
chute and large enough to provide insertion and removal areas
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for the package.
It would be desirable to devise a strapping
method and machine wherein the strap loop could be formed
without the need for a large, ring-like chute into which a
packaqe must be inserted. Use of such a method would re-
quire relatively less space than the present method that
requires a chute. Thus, a method that does not require a
chute could be performed on a work table or desk and could
be used for strapping small packages.
; ; 10 Automatic strapping machines which use ring-
like chutes to form the loop about the package are some-
what inefficient with respect to strapping different size
package~. For example, if a strapping machine is intended
to strap large packages, say three feet in diameter, then
the strap chute must be at least throe feet in diameter.
If, subsequently, the machine is used to strap much smaller
packages, say one foot in diameter, then the strap loop
fonmed around the smaller package is initially three feet
in dlameter and the machine must withdraw a substantial
amount of trailing strap during the tensioning process to
decrease the diameter of the loop and tighten it ~bout the
one-foot diameter package. This is obviously inefficient.
Therefore, it would be desirable to provide a method and
~ . . . .
machine for forming a strap loop of any desired size. Such
a method and machine would advantageously be used in strap-
ping operations where the size of the packages would vary.
Thermoplastic strapping machines currently avail-
able also suffer from some drawbacks relating to the forma-
tion of the friction-fusion weld. In order to form a friction-
fu~ion weld on the overlapped portion of the strap loop, an
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~ 1063501
anvil or bearing member must be inserted between the package
and the strap loop to provide a rigid bearing surface against
which the overlapping strap portions are pressed by an oscil-
lating weld member. The anvil member prevents the strap loop
from lying flat against the surface of the package at that
point and therefore introduces ~lack into the loop. However,
owing to the flexibility of the strap, a tight loop can
usually be obtained with large and slightly resilient pack-
ages. Unfortunately, though, with very ~mall packages and/
or with package~ having relatively rigid, incompressible
surfaces, the amount of slack introduced into the ~trap loop
by the inserted anvil can be significant and can result in
a loose strap loop when the anvil i8 retracted from between
the strap and the package. Accordingly, it is de~irable to
provide a method and apparatus for welding the strap loop in
a manner that does not require the lnsortion of an anvil
member between the strap and the package.
SUMMARY OF THE INVENTION
The method and apparatus of the present invention
utillzes a novel concept of first forming a small, or pri-
mary, strap loop and then expanding the formed primary loop
to a larger predetermlned size. Formation of the primary
loop can be accomplished without the use of a ring-like
chute into which the package to be strapped must be placed.
In the preferred embodiment of the method of the
present invention, the primary strap loop is formed by
feeding a length of strap into a substantially circular
guide or cup 80 that the strap free end is guided around
in a circle by the inner periphery of the cup to form a
loop with the strap free end overlapping a portion of the
,. _ __ _ _ _. _ _ . ,, . _ ... . . .. _ .. . . . . .. .. . .
~: i063501
loop. Next, the formed primary strap loop is held, gripped
or guided to maintain the primary strap loop in the plane
of its original formation and the circular cup is lowered
away from the primary loop in a direction normal to the
plane of the loop. The loop i8 then expanded to a size
large enough to fit around the particular package to be
strapped. More specifically, the strap free end is gripped
or restrained from further movement while the standing length
; of strap is continued to be fed to expand the loop to the
desired size. The package i8 then moved near, or over, a
portion of the expanded loop and the loop is placed about
the package, after which the loop $8 tensioned to tighten
; it about the package. When the loop has been sufficiently
tightened, the strap free end i8 connected or ~oined to an
ad~cent overlapping portion of the loop by appropriate means,
such as by friction fusion, application of an lndependent
seal, or by formation of an interlocking slit type ~oint.
The completed loop can then be severed from the trailing
length of strap.
In the preferred embodiment of the apparatus of
~i; the present invention, a supply of strap is threaded in
guideways in a horizontal ~trap transport zone below a hori-
zontal package support surface. The strap is further threaded
between a traction wheel and an idler wheel, the traction wheel
being driven by an electric motor to advance the strap for-
ward when feeding the strap to form a loop and to withdraw
the strap backwards when tensioning the loop.
A cylindrical cup is provided to receive the free
end of the strap as it is fed forward. The strap enters the
cup through an opening or slot in the cylindrical side of
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the cup and impinges upon the interior surface of the cup
where the strap is further guided in a closed arcuate path
to form a small primary strap loop with the free end over-
lapping a portion of the strap loop. The cup is mounted for
movement between thiis first, strap receiving, position and
a second position beneath the first position. After the
strap loop has been formed, the cup is lowered to the
second position and the formed primary strap loop, being
supported by thie standing length of strap in the strap
transport zone guideways, remains suspended at the elevated
first position above the lowered cup.
A combination cylindrical gripping/welding member
extends through the bottom of the cylindrical cup and up
.~.,
into the inside of the formed primary strap loop. A mov-
able anvil member is provided on the exterior of the formed
strap loop and is movable toward and away from the combina-
tion gripping/welding member. When the cup has been moved
to the lowered position below the fonmed primary strap loop,
the anvil member is moved toward the gripping/welding member
and presses the overlapped portion of the strap loop there-
between. The gripping/welding member has a rough peripheral
gripping surface which engages a side of the strap free end
, .
while the anvil surface contacting the side of the over-
lapped portion of the loop is smooth. Thus, as the strap
continues to be fed, the strap free end is restrained from
movement and the overlapped portion of the loop slides
between the strap free end and the smooth surface of the
anvil to expand the loop to a larger diameter. When a pre-
determined larger diameter has been reached, the feeding
of the strap is terminated.
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- A package, having been placed upon the raised
package support surface adjacent the overlapped portion
of the strap loop, is then ved forward to overhang the
horizontally oriented loop. The operator then grasps the
strap loop and lifts it around the package by twisting the
7'
loop about the restrained overlapping strap area to a
vertical orientation about the package. Reversal of the
traction wheel withdraws the standing portion of the length
of strap to tighten the loop about the package. When the
strap is tensioned to tighten the loop, the gripping/welding
member is still engaged with the strap free end to prevent
its movement and to allow the loop to be tightened.
As the loop is tightened about the package, the
; ~ strap free end and the adjacent overlapped loop portion of
the strsp between the anvil member and the gripping/welding
; j, member are oriented with their sides perpendicular to the
bottom surface of the package and lying in the plane of
the loop about the package. In this configuration, the
strap loop i8 next friction-fusion welded in the overlapping
,
area. The gripping/welding member is rotatably oscillated
at a high frequency to move the strap free end back and
`~ forth relative to the overlapped portion of the strap loop
thereby generating sufficient friction heat to fuse the
strap free end to the overlapped portion of the loop. A
cutter blade is provided to sever the standing length of
: . .
strap from the loop. Next, as the anvil is retracted away
from the gripping/welding member, the twisted, overlapped
portion of the loop twists back to assume the nonmal
orientation lying flat against the package. The package
can then be removed from the apparatus.
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Numerous other advantages and features of the
present invention will become readily apparent from the
following detailed description of the invention and embodi-
ments 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,
Figure 1 is a partial perspective view of a
preferred embodiment of the apparatus of the present
invention;
Figure 2 is a partial perspective view similar
to Figure 1 and showing a package on the apparatus with the
strap cup in raised position7
Figure 3 is a partial perspective view similar
to Figure 2 showing the strap cup in the lowered position
and the strap being expanded to a predetermined larger dia-
meter;
Figure 4 is a partial perspective view similar
to Figure 3 showing the expanded strap loop being located
about the package;
Figure 5 is a partial perspective view similar toFigure 4 showing the strap loop tensioned about the package;
Figure 6 is a partial fragmentary perspective view
of the apparatus shown in Figure l;
Figure 7 is an enlarged, partial, fragmentary top
view of the apparatus shown in Figure 2 with the strap cup
: in raised position and a length of strap formed into a loop
within the cup;
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- Figure 8 is a sectional view taken generally
along the plane 8-8 of Figure 7;
Figure 9 is an enlarged, partial, fragmentary
- top view similar to Figure 7 but with the strap cup in
the lowered position and the strap loop expanded to a larger
. ~ predetermined diameter;
Figure 10 is a sectional view taken generally
along the plane 10-10 of Figure 9;
Figure 11 is a sectional view similar to Figure
. ~ .
.,. 10 10 showing the expanded loop located about a package;
`.: Figure 12 is an enlarged, partial top view of
the apparatus shown in Figure 6 showing in detail the
strap tension sensing mechanism;
Figure 13 is a schematic diagram of the pneu-
matic control system for the apparatu~ of the present
inventian;
Figure 14 is a simplified control block diagram
for the apparatus of the present invention;
Figure 15 is a top view similar to Figure 2 of
the strap loop forming area of a second embodiment of an
apparatus for strapping a package according to the method
; of the present invention;
Figure 16 is a view similar to Figure 15 showing
.~ the method of expanding the strap loop to a larger diameters
~: Figure 17 is a cross-sectional view taken generally
;; ~ along the plane 17-17 of Figure 15;
Figure 18 is a view similar to Figure 8 illus-
F trating the strap loop forming area of a third embodiment
: of an apparatus for strapping a package according to the
30 method of the present invention;
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Figure 19 is a cross-sectional view of the
strap loop forming area of a fourth embodiment of an
apparatus for strapping a package according to the method
. i,..~
of the present invention;
Figure 20 is a reduced cross-sectional view taken
generally along the plane 20-20 of Figure 19;
Figure 21 is a top view of the strap loop form-
; ing area of a fifth embodiment of an apparatus for strap-
: ping a package according to the method of tho present
invention;
Figure 22 is a simplified diagrammatic top view
of the strap loop forming area of a sixth embodiment of an
; apparatus for strapping a package according to the method
of the present inventian~
.~ : Figure 23 is a view of the sixth embodiment,
similar to Figure 22, illustrating th- formation of a
primary strap loop;
Figure 24 is a view of the sixth embodiment,
similar to Figure 23, illustrating the formation of an
expanded strap loop;
.;, ~
Figure 25 is a view of the sixth embodiment,
similar to Figure 24 but much reduced in scale, to show an
expanded strap loop pl~ced about a package;
:~ Figure 26 i8 a top view of the strap loop forming
~ area of a seventh embodiment of an apparatus for strapping
};:: a package according to the method of the present invention;
. ~:
Figure 27 is a cross-sectional view taken gener-
ally along the plane 27-27 of Figure 26 showing a primary
-: strap loop being lifted from a guide;
Figure 28 is a top view of the seventh embodiment,
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`1063501
similar to Figure 26, showing an expanded strap loop.
Figure 29, appearing on the same sheet of draw-
ings as Figures 20 and 21, is a cross-sectional view of
the strap loop forming area of an eighth embodiment of an
apparatus for strapping a package according to the method
.~,,~ .
of the present invention;
Figure 30, appearing on the same sheet of draw-
ings as Figures 20 and 21, is a cross-sectional view taken
generally along the plane 30-30 of Figure 29; and
Figure 31, appearing on the same sheet of draw-
ings as Figures 20 and 21, is a simplified, partially
schematic diagram illustrating another form of a primary `
strap loop according to the method of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
While this invention is susceptible of embodiment
in many different forms, there are shown in the drawings
and will herein be described in detail several preferred
embodiments of the invention. It should be understood,
however, 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 embodi-
ments illustrated.
For ease of description, the various embodiments
of the apparatus that may be used for strapping a package
according to the method of this invention will be described
in 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 which is used to effect the
~3~method of this invention may be manufactured, stored,
transported, sold and operated in an orientation other
than the normal operation position described.
The apparatus illustrated herein which may be
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used to effect the method of this invention has certain
conventional drlve mechanisms and control mechanisms which,
though not fully illustrated or described, will be apparent
to those having skill in the art and an understanding of
the necessary functions of such drive mechanisms causing
proper operation of the apparatus as will be explained.
A preferred embodiment of the expanding strap loop
forming and friction fusion apparatus in accordance with the
present invention is designated generally as 20 in Figure 1.
Preferably, the apparatus is of a size suitable for being
placed on a worktable or desk and is advantageously used
to strap rectangular parallelpiped-shaped packages having
dimensions of between 5 and 40 inches on each side. How-
ever, the apparatus can accommodate much larger or smaller
packages and packages of different shapes.
As shown in Figure 2, the apparatus 20 of the
present invention has a package support surface 22 for
supporting a package 24. The apparatus 20 has a lower
surface or shoulder 26 stepped below the elevation of
the package support surface 22.
OUTLINE OF THE MAJOR STEPS OF THE STRAPPING SEQUENCE
To aid in understanding the details of con-
struction of the apparatus 20, a brief outline of the process
of forming and securing a strap loop about a package will
first be given.
As illustrated in Figure 2, a package 24 is
first placed upon the package support surface 22 near
shoulder 26. A cylindrical cup 28 is raised from a posi-
tion below the surface of shoulder 26 to an elevated posi-
tion above the surface of shoulder 26. By a novel means,
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as will be described in detail hereinafter, a length of
strap i8 fed into the cup to form a primary strap loop.
The cup 28 is then lowered to a position below the surface
; of shoulder 26 while the loop i8 maintained at the higher
elevation where it is expanded to a predetermined larger
diameter loop 30 as illustrated in Figure 3. Next, the
operator slides the package 24 forward to overhang shoulder
26 and then places the expanded loop 30 about the package
24 as illustrated in Figure 5. The strap is tonsloned to
draw the loop tight about the package. The entire process
is completed when the tensioned loop is friction fusion
welded to form a connection and then severed from the
.. ~ .: .
~ strap supply.
.. 1 .
., .,;
The speclfic features of the apparatus used to
accomplish the above-described package strapping process
will next be discussed in detail. The ma~or foatures or
mechanisms of the apparatus ares 1) the strap loop form-
ing mochanism; 2) the strap feed and tensioning mechanism;
3) the ~trap loop friction fusion mechanism; 4) the strap
~evering mechanism; 5) the pneumatic actuat$on system, and
6) the electrical control system.
STRAP LOOP FORMING MECHANISM
A novel feature of the present invention is the
mechanism automatically for first forming a primary strap
loop that can be subsequently expanded to any larger size.
The apparatus for forming the primary strap loop is most
clearly shown in Figures 6 through 11.
~ By a strap feed mechanism described hereinafter,
i~ the strap is fed into a guide means. A circular band
~; 30 member, or cup 28, provides a circular guide means for
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~ 1063501
forming the primary strap loop. Cup 28 is a substantially
cylindrical member and may or may not have open ends. In
the preferred embodiment illustrated, cup 28 has a par-
. .
tially closed bottom and an open top. A portion of the
vertical cylindrical wall of the cup 28 is cut away to form
a relatively large opening or slot 34 for receiving a length
of strap 36 as shown in Figure 7. The cup 28 guides the
strap free end 38 in a closed arcuate path whereby the free
end 38 is directed back upon the length of strap 36 to form
the initial primary strap loop with the free end of the strap
overlapping a portion of the formed strap loop.
The cup 28 is movable between an upper, or raised
position, and a lowered position. The mechanism for ralsing
and lowering the cup 28 may be of any appropriate type. As
illustrated in Figure 6, the cup 28 i~ secured to a drive
member 64 which i8 attached to an electric solenoid actuator
66.
The length of strap 36 is oriented with its side
~urfaces perpendicular to the plane of the package support
8urface 22 and is guided beneath the package support surface
22 in a strap transport zone 40 which lies between the pack-
age support surface 22 and the plane of shoulder 26. The
~trap transport zone 40 has a thickness substantially equal
to the width of the length of strap 36 and is essentially
a stratum in which the length of strap 36 is fed, guided,
formed into a primary loop, expanded into a larger loop,
tensioned, friction welded and severed. In the raised posi-
tion tas illustrated in Figure 2), the cup 28 lies in the
.: .
strap transport zone 40. In the lowered position (as
illustrated in Figures 1 and 6), the cup 28 lies below the
~ ` '
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1063501
strap transport zone 40. The length of strap 36 is guided
within the strap transport zone 40 by appropriate guideways
42 as illustrated in Figure 6. The strap is also fed for- -
ward and tensioned backwards through the guideways 42 in zone
40 by appropriate traction drive means as will be described
hereinafter.
During loop formation, the strap free end 38 i9
1) guided into the cup slot 34, 2) maintained within the
,~,. -~ ; ~,
cup 28 by upper and lower guides, and 3) restrained above
cup 28 during lowering of cup 28 and subsequent expansion
of the loop. These guides and strap restraining means will
be described with reference to Figure 7. Adjacent slot
34 is an anvil 44 which is mounted on movable slide 46. A
portion of anvil 44 adjacent the length of strap 36 has a
~mooth-surfaced polyurothane pad 48 ~ecured thereto for
guidlng and contacting length of ~trap 36 as wlll be described
hereinafter. Opposite the polyurethane pad 48 is a cylindri-
cal member, or weld head 52, which uniquely serves two func-
tionss 1) gripping the strap free end 38 and 2) welding the
free end to the overlapped portion of the loop. The welding
function will be described later. At this point, just the
l~ ~ gripping or restraining feature of the weld head will be
discussed. The weld head 52 is mounted on shaft 53 and is
a substantially cylindrical member having a rough, peri-
pheral gripping surface 54 adapted for contacting a side of
the strap free end 38. Both the weld head 52 and the anvil
44 lie in the strap transport zone 40 as illustrated in
~ ,. 1 ,
Figure 8. The anvil 44 is movable, by air cylinder actuator
means to be described later, within the transport zone 40
in a horizontal plane towards and away from the weld head
. I
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1063501
4 52- When the cup 28 is in the raised position as illustrated
in Figures 7 and 8, the anvil 44 can be ved towards the
weld head 52 to a position spaced away from the weld heaa
gripping surface 54 where a portion of the anvil 44 contacts
the cup 28 at abutment surface 56 and remains biased there-
against. In this position there is sufficient clearance
between the weld head gripping surface 54 and the polyure-
thane pad 48 to allow the length of ~trap 36 and the over-
lapping free end 38 to lie therebetween. When the cup 28 is
lower-d below the surface of shoulder 26, the anvil 44, being
biased towards the weld head 52, moves toward the weld head
52 to bring the polyurethane pad 48 into contact with the
length of strap 36 lying therebetween to restrain the over-
lapping strap free end 38 from ~ovement.
As lllustrated in Figure 6, the movement of anYil
slide 46 18 effected by a pneumatic cylinder actuator 120
whioh acts through a piston rod 122 connected on one end to
the cylinder piston ~not shown) and on the other end to the
. .
slide 46.
Referring now to Figure 7, the detailed formation
of the primary strap loop will now be described. First,
the free end 38 of a length of strap 36 is fed forward in
the strap transport zone 40 between the strap transport
guideways 42 and through aperture 34 of cup 28. The strap
.~
~` free end 38 is guided by polyurethane pad 48 and a portion
of anvil 44 as it enters the interior of cup 28. The strap
free end 38 is guided by the interior surface of cup 28 in
a closed arcuate path to form an initial primary loop with
the free end 38 overlapping a portion of the loop between
-~ 30 the anvil 44 and the weld head 52. By suitable control means
., :
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1063501
as will hereinafter be described, the feeding of the strap
length 36 i8 terminated when the primary loop has been formed
. essentially as illustrated in Figure 7.
^~ ~ It i8 desirable during the primary loop formation
stage, as well as during subsequent tensioning and welding
stages, to maintain the overlapped portion of the strap
length 36 and the free end 38 in the elevation of the strap
- transport zone 40. To this end, appropriate upper and lower
guides are provided. A flange 60 is provided in the lower
:~ 10 ond of the weld head 52 for keeping the overlapped portion
; of the strap length 36 and strap free end 38 from running
below weld head 52. A slide cover 62 is secured to, and
movable with, slide 46 above the strap transport zone 40
to prevent the overlapped portion of tho length of strap 36
and the strap free end 38 from riding above the weld head 52
and the polyurethane pad 48.
After the primary strap loop has been formed, the
cup 28 must be lowered from its elevated position in the
. . i
~i strap transport zone 40 to a second position below the strap
~;' " 20 transport zone 40. As the cup i~ lowered,the formed pri-
mary strap loop does not ride in the cup 28 to the lowered
` position, but rather slides out of the cup and remains at
~.. .
: the upper position. This is due to the combination of the
~ : relatively small diameter of the cup 28, the stiffness of
. . .
the strap, the low coefficient of friction between the strap
and the cup, and the fact that the strap length 36 i8 sup-
~ ; ported on its bottom edge in the strap transport zone guides
~ 42. Consequently, when the cup 28 is lowered, the formed
a; ~ primary strap loop is maintained at the elevation of the
;~ 30 strap transport zone 40 above the top surface of the shoulder
. 26.
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1063501
After the cup 28 is completely lowered away from
the primary strap loop, any tendency of the loop to uncoil
or unwind is resisted. Owing to the proximity of the weld
head 52 and the polyurethane pad 48 on opposite sides of
the overlapping strap portions of the loop, the loop is not
able to unwind and is thus maintained in a loop.
A novel combination of mechanisms is used to
expand the formed primary strap loop to a larger loop of
predetermined diameter. With the cup 28 in the lowered
position as illustrated in Figures 9 and 10, slide cover 62,
anvil 44 and polyurethane pad 48 move clo~er toward weld
head 52 by slide 46 under the influence of a biasing means
described hereinafter. Anvil 44 is moved forward to force
polyurethane pad 48 against the strap loop in a region where
the strap free end 38 overlaps the overlapped portion of
the loop formed by the length of strap 36. The polyurethane
pad 48 then contacts a side of the length of strap 36 to
force both the length of strap 36 and the overlapping
; strap free end 38 against weld head 52. By means that will
be described later, the polyurethane pad 48 is maintained
l against the loop with a relatively small amount of force
; such that the strap free end 38 is restrained from moving
by the weld head roughened peripheral gripping surface 54.
However, the force is low enough (about 2 pounds) to permit
the overlapped length of strap 36 to slide forward between
~i the strap free end 38 and the smooth - surfaced polyurethane
pad 48 when the length of strap 36 is fed to expand the
loop. Preferably, during the expansion of the primary
... . .
strap loop, the surface of shoulder 26 provides the support
for the bottom of the strap loop as it expands.
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- 1063501 :: ~
Though the surface 54 of the weld head 52 is prefer-
ably roughened (espeeially on account of its gripping function
during the subsequent frietion fusion process to be deseribed
- below), it need not necessarily be 80. Insofar as the hoad
52 functions during the loop expansion process, the head 52 need
~ only have some sufficiently relatively greater coefficient of
; sliding frietion than the pad 48. Alternatively, the pad 48
eould be replaeed by a cylindrical roller mechanism which would
rotate about an axis parallel to the weld head shaft 53 to allow
; 10 feeding and tensioning of the strap. The roller could be lockod
against rotation, if neeessary, during tho subsequent frietion
fusion proeess (to be deseribed below).
, After the loop has been expanded to the predetermined
c-~, larger diameter and placed around tho package 24 as shown in
~ Figures 4 and 11, the loop 30 18 tensioned and tightened about
; ~ the paekage 24. The detail~ of th meehanism for applying
l ten~ion to the strap wlll be diseus~-d later. It is fir~t
-~ nece-sary to deseribe the aetion of the polyurethane pad 48
; and the weld head 52 during the tensioning proeess. At the
beginning of the tensioning phase, the strap loop 30 is dis-
posed about the paekage 24 as illustrated in Figure 11. At
I
this timo, the cup 28 is in tho lowerod position below the
~urface of the shoulder 26. The strap loop 30 i8 tensioned about
the paekage 24 to form a tight loop as illustrated in Figure 5.
During tensioning, a tensile foree is transmitted along the
~¦ length of the strap 36 which is eonsiderably higher than the
;~l small eompressive force whieh exi~ts in the portion of the strap." .,
between the strap feed meehanism and the polyurethane pad 48 as
the strap is being fed to form the expanded loop. Consequently,
during tensioning the higher force oceurring in the ~trap would
. ",.~
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1063501
tend to pull the strap free end 38 from its restrained engagement
against weld head 52. To overcome this possibility, the poly-
urethane pad 48 is forced against the strap and weld head 52
during tensioning with a large force to cause strap free end 38
to remain restrained against~the wëld head 52. In the preferred
embodiment o. the present invention, it has been found that a
force of about 30 bo 40 pounds is sufficient to m~intain the strap free
end 38 between the polyurethane pad 48 and the weld head 52 as
~the overlapped length of strap 36 is tensioned. Typically, the
; ~ 10 ~trap loop is tensioned to about 10 to 15 pounds.
; During the tension~ng process, as illustrated in
Figure 11, the upper edge ofthe strap, in the region of the
~trap overlap between the polyurethane pad 48 and the weld
;head 52, ~s nearer the bottom ~urface of the package 24 than
- ;' i8 the bottom edge of the ~trap. Preferably, the strap loop
30 is maintained in the 90 twist orientation illustratea in
Pigure 11 such that both the upper and lower edges of the
strap in the region between the polyurethane pad 48 and the
weld head 52 are located in the plane of the loop as the loop
,~ 20 is tensioned about the package 24. Although the sliding sur-
" ~ . .
face of polyurethane pad 48 and the opposed gripping surface
54 of weld head 52 are shown in Figure 11 as being perpendicula~
to the slide cover 62 and to the bottom of the package 24, such
,. ~
~orientation is not necessarily ~equired. The surfaces on both ~
., .. ~ . ,.
the polyurethane pad 48 and the weld head 52 could be angled
witb respect to the plane of the strap loop 30 about the pack-
age 24. ~ -
During the tensioning process, slide c~ver 62 lies
between the bottom surface of package 24 and the strap loop
30. With some types of soft packages and at certain hish
.
; -21-
, . . .
.
' " ' . . : ' . . ' :
1063501
tension levels, the slide cover 62 serves to prevent the loop
30 from pulling out of engagement from between the polyurethane
pad 48 and the weld head 52. After tensioning, when the slide
cover 62 is removed from between the package 24 and the loop
30 as will be described hereinafter, a certain amount of slack
is thus present in the tightened loop. However, due to the
elasticity of the plastic strap and due to the compressibility
of the package 24, a tight loop is nevertheless achieved when
the slide cover 62 i8 removed. Additionally, the slide cover
.
` 10 62 can be made relatively thin (in the vertical diredtion as
viewed in Figure 11) and can be made relatively narrow with
respect to the package width (as viewed in the horizontal
direction in Figure 2) to minimize the amount of slack formation.
Further, with certain types of packages (such as those
having rather rigid and incompressible surfaces), and with
low loop tension~, the sllde cover 62 Can be eli~inated
; altogether. ~his i8 because, at low tension levels, the strap
; loop has less of a tendency to be pulled out of engagement
from between the polyurethane pad 48 and the weld head 52.
Further, the relative incompressibility of the package 24
would prevent the strap loop 30 from sinking into the package
and pulling away from the polyurethane paa 48 and the weld
,.. . .
head 52.
... . . .
~il ; Although the tensioning process is illustrated in
.
~ Figure 11 as occurring with the overlapped portions of the
. ~ ,
~' strap loop oriented in a plane parallel to the plane of the
strap loop about the package, the loop 30 could be tensioned
in other orientations. With very large packages and with
~.
~-- very small weld head diameters, it would be possible to
~- 30 insert the package into the expanded loop when the loop is ln
-22-
_ . .. ,_,. ._ . . . , _ . , , _ .. _.. _, , .. . _ ,_ " _ .. , ,. ~ , . . .. . ... . . . .
1063501
the horizontal position as shown in Figure 3. Then the loop
could be tensioned in that horizontal configuration. Though
the diameter of the weld head 52 would create some amount of
slack in the tensioned loop, with large compressible packages
such slack would be negligible and would not affect the integ-
rity of the tightened loop. If the strap loop was to be ten-
sioned about the package in the horizontal direction, then
the upper surface of shoulder 26 would advantageously be
located at a lower elevation with respect to the weld head
.
, ,,~ 10 52 and the strap transport zone 40 than is shown in,Figure 6.
;' The increased depth would accommodate placement and insertion
; of large packages within the horizontally oriented loop. Of ;,
course, if the loop were to be tensioned in the horizontal
~ direction, provisions could also be made for automatically
,~ withdrawing the weld head 52 from between the strap and the ' '
, package after the tensioning proces~ has been completed.
, ~
', STRAP FEED AND TENSIONING MECHANISM
,' The strap is both fed and tensioned by one traction
,, wheel assembly. A traction wheel 68 and adjacent idler wheel
~ ,-.................................................................... .
70 are mounted for horizontal rotation in the strap transport
,~ ~one 40 as illustrated in Pigure 6. The idler wheel 70 i8
~,'` preferably spring-biased against the traction wheel 68. The ,-
i :
strap 36 is threaded in the guideways 42 and between the trac-
,ion and idler wheel,s C8 and 70, respectively. Traction wheel
68 is mounted on a shaft 72 and is rotatably drivable in either
' ~ direction by an electric motor 76 which is connected to the
, ,~ shaft'by a conventional drive belt 78. The motor can drive
' ~ the traction wheel 68 first clockwise (as viewed in Figure 6)
. . ~
,, to feed the strap to form the loop and then counterclockwise
: .
(as viewed in Figure 6) to tension the loop.
.
."'
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~,' ' .
1063501
A bulk supply of strap is preferably wound on a
conventional self-supporting spool (not shown) which can be
placed near the apparatus 20 and which rotates to deliver
strap in response to the feed force of the traction wheel
pulling on the strap.
On the end of the shaft 72 opposite the traction
wheel is an incremental rotation control unit 74 which signals
the cup solenoid actuator 66 to lower cup 28 after the primary
strap loop has been formed. Contro1 unit 74 is of a convention-
al type which incorporates an electrically actuated clutch.
When the clutch is actuated, a cam member rotates with the
~haft 72 for one revolution, after which the clutch disengages
the cam member from the shaft 72 and locks the cam against
.,; .
further rotation. The cup solenoid actuator 66 i8 de-energized
; to lower the cup 28 by a l~mit switch provided in the control
unit 74 and which is actuated by the rotating cam after one
rotntion of the cam. In order that a single rotation of the
; traction wheel 68 causes the primary ~trap loop to be formed
j~ within the cup 28 with the strap free end overlapping a por-
; 20 tion of the loop, the diameter of the traction wheel 68 is
larger than the diameter of the cup 28.
After formation of the primary strap loop in the
t~ CUp 28, cup 28 is lowered away from the loop allowing the
traction wheel 68 to expand the loop to a pxedetermined size.
Actually, since the cup 28 is lowered quite rapidly by the
solenoid actuator 660 it is not necessary to terminate the
strap feeding process while the cup 28 is being lowered. Thus,
the strap is continuously fed without interruption until the
desired expanded loop diameter is achieved.
- 30 The tensioning process is terminated when the desired
level of loop tension is sensed. A tension sensing assembly
-24-
'~ .
.
1~63501
is provided in the strap transport zone 40 and is illustrated
in Figures 7, 9 and 12. A tension sensing wheel 83 is rotatably
mounted about shaft 84 on arm 86. Arm 86 is pivotally mounted
about shaft 88 to frame plate 90. Spring 92 is secured on one
end to arm 86 and on the other end to an anchor 94 in the frame.
The spring 92 functions to pivot arm 86 counterclockwise about
shaft 88 to bias the tension sensing wheel 83 against the side
wall region 95 in strap transport zone guideway 42. The tension
of spring 92 is adjustable and can be set to permit a given
amount of spring extension at a predetermined strap tension
. .
level. When the strap is under little or no tension, the
strap length 36 is forced by the wheel against the side wall
region 95 in guideway 42 as illustrated in Figures 7 and 9. ;
As the tension increases, the strap length 36 forces wheel 83
out from the wall region 95 because the tensioned strap 36 is
drawn into a straight line between point 96 and point 97 in
guideway 42. The present spring tension ls set 80 that the strap
length 36 is prevented from forming a straight line between
points 96 and 97 until the strap tension reaches the predeter-
mined level. When the predetermined strap level is reached,
the tension sensing wheel 83 is ~orced by the straight portion
of strap length 36 to the position illustrated in Figure 12
where the arm 86 bears against contact arm 98 of a limit switch
100. Actuatic~ of the limit switch 100 in this manner opens
the circuit of motor 76 to terminate the tensioning.
STRAP LOOP FRICTION FUSION MECHANISM
The method and mechanism for connecting the strap
free end 38 to the overlapped portion of the length of strap
36 will now be described. If a plastic or plastic-coated met-
al strap is used,a welded or friction-fused joint can be
achieved by heating the overlapped region of the loop.
: '
-25-
.. . - ~ - .
" .. . : . ' ~ ~ ' ,
`- 1063501
In the preferred embodiment, the fusion heat is
generated by rapidly moving the strap free end 38 against the
overlapped portion of the length of strap 36 to qenerate heat
by friction and effect interface melting therebetween. More
particularly, this is accomplished by oscillating the weld
head 52 with a relatively small angular rotation at a suffi-
ciently high frequency. Weld head 52 is rotatably oscillated
about the shaft 53 80 that the peripheral gripping surface 54,
being engaged with a side of the strap free end 38, causes the
strap free end 38 to be moved back and forth with respect to
the stationary overlapped portion of the length of strap 36.
Typically, the frequency of oscillation is between about 50 and
100 hertz, the total amplitude of circumferential rotation of
the gripping surface 54 is about 0.15 inch, and the oscillation
,,~ .
period lasts from between ~75 to 1.0 ~econd. In order to insure
an adequate weld, the polyurethane pad 48 is pressed against tho
overlapped portion of the longth of strap 36 with a higher force
than is used during the tensioning process. Typically, a force
of about 100 pounds is impressed against the strap during the
friction-fusion process.
The weld head 52 is driven in the oscillatory mode
by motor 80 and a connected oscillating drive transmission 82.
The motor 80, transmission 82, and control means (not shown)
are well known and commerically used in present friction fusion
! ~ strapping machines. A description of such mechanisms can be
found in the U.S. Patent to Ericsson, No. 3,586,572.
The friction fusion joint could be formed with a
different type of anvil apparatus than illustrated. For
example, pad 48 could be replaced with a cylindrical roller
mounted for rotation about an axis parallel to the weld head
-26-
':
~'
1063501
shaft 53 and having a roughened gripping surface. The
rotation of the roller would allow for the feeding and
tensioning of the strap. Then after the loop had been
tensioned, the roller could be oscillated vertically
(along its axis) by a suitable mechanism to vibrate the
strap 36 against the free end 38 to create a fused joint.
After the friction-fusion joint has been com-
pleted, the cup 28 is still maintained in the lowered
position below the surface of shoulder 26 while the weld
head 52 and the polyurethane pad 48 are maintained in com-
pressive engagement on the strap loop so that the strap
loop can be severed from a standing portion of the strap
length 36 as will be next described in detail.
With metal strap, other types of ~oints could be
created through the use of additional, conventional ~oint
forming mechanisms (not illustrated). Such other ~oints
may be, for example, of the independent seal type or of
the interlocking slit type. Descriptions of such seals and
sealing mechanisms can be found in the U.S. patents to Crosby,
No. 2,710,435; to Crosby et al., No. 2,801,558; and to Beach,
No. 3,303,541.
STRAP SEVERING MECHANISM
After the loop has been connected by the friction-
fusion weld, the standing portion of the strap is severed
from the loop by cutter 102 as best illustrated in Figures 6
and 9.
The cutter blade 102 is fixed in a slide block 104
which is slidably mounted for movement toward and away from
strap 37 as best-shown in Figure 9. A cutter block 196 is
provided to guide strap 36 to prevent the strap from deflect-
-27-
- .
1063501
ing away from the cutter blade 102 as it is moved forward
to sever the strap.
The Gutter blade 102 i8 moved through a linkage
,........................................................................... .
by a pneumatic cylinder actuator 109. As illustrated in
Figure 6, link 108 is pivotally mounted about shaft 110
and is pivotally connected to arm 111 on one end and to
cutter block 106 on the other end. Arm 111 i8 connected
to the cutter air cylinder actuator 109 through a conven-
tional cylinder piston rod (not shown). Pressurization of
the cylinder actuator 109 forces the cylinder piston rod
and arm 111 toward the cylinder actuator to pivot link 108
counterclockwise (as viewed in Figure 6) about shaft 110
thereby moving the cutter blade 102 forward to sever the
.i ,
strap. The cylinder actuator is equipped with an internal
~pring to return the piston rod to tho extended position
(and hence the cutter blade 102 to the retracted position)
upon release of cylinder air pressure.
After the strap has been severed, the anvil slide
46 is moved away from the weld head 52 to retract the anvil
44 4nd the slide cover 62. With the anvil 44 retracted,
the fused portion of the strap loop adjacent the weld head
52 is relieved from its 90 twist configuration with respect
to the balance of the loop and lies flat along the bottom
surface of the package. Since the slide cover 62 is also
retracted, the tensioned strap loop tightens further,
under influence of its elasticity, to fit tight around a
, . I
portion of the surface of the package that was previously
in contact with the slide cover 62. The strapped package
- can then be removed from the apparatus.
PNEUMATIC ACTUATION SYSTEM
:
As previously described, the movement of cutter
-28-
1063501
..
blade 102 and anvil slide 46 is effected by pneumatic
cylinder actuators 109 and 120, respectively. The actua- -
tors are controlled by a pneumatic actuation system illus- -~
trated schematically in Figure 13.
The system is comprised of a supply manifold 124
supplying 90 p8i air to three pressure regulating valves
126, 128, and 130 downstream of which are three-way electri-
cally operated solenoid valves 132, 134, and 136, respectively.
The solenoid valves admit air to a distribution manifold 137
for supplying the cylinder actuators 109 and 120. A check
valve 138 prevents flow from solenoid valves 132 and 134
from pressurizing the cutter cylinder actuator 109. Cylinder
actuator 109 can thus be pressurized only from solenoid valve
136 through a flow control valve 139.
Pressure regulating valves 126, 128, and 130 are
set to control pressure to relative ~low, n nmedium~ n and
~high~ pressure levels, respectively, for purposes to be
explained hereinafter. The solenoid valves 132, 134, and
136 each have three ports (labeled A, B, and C in Figure 13).
Exhaust port C is plugged in valves 134 and 136, but is
unplugged to exhaust to atmosphere in valve 132. In the
de-energized state, the solenoid valves are set to pass
,; .
flow through ports B and C ~except that port C is plugged
on valves 134 and 136) and in the energized state the
~` valves pass flow through ports A and B.
~he actuation of the anvil cylinder actuator 120
will now be considered. When the primary strap loop is
first formed in cup 28, the anvil 44 is moved forward to
contact abutment surface 56 as illustrated in Figure 7.
- 30 With reference now to Figure 13 also, it can be seen that
29
. .......................................................................... .
,:
:. . .
1063501
movement of anvil 44 to this position is accomplished by
~ sctuating air solenoid valve 132 to open ports A and B to
; allow a regulated low air pressure from pressure regulating
.. . . valve 126 to act upon the piston in cylinder actuator 120
~` and force anvil 44 against the cup abutment surface 56 with
; about 2 pounds of force. The 2 pounds of force i8 a nominal
~; amount that is used to insure that the anvil 44 i8 abutting
the cup 28 to provide proper alignment and guiding of the
; strap free end 38 as it is fed forward into aperture 34 and
between polyurethane pad 48 and weld head 52.
After the primary strap loop has been formed in
cup 28, cup 28 is lowered to below the surface of shoulder
26. As cup 28 is being lowered, cup abutment surface 56
slides vertically downward along the front of anv~l 44. As
j soon as cup 28 has cleared the bottom of anvil 44, anvil 44
is urged forward against the strap and weld head 52 by the
2 pounds of force that is still maintained by the anvil air
'I
cylinder actuator 120. The loop is expanded to a larger
~; dlameter with the anvil 44 maintaining the 2 pounds of force
'':", ~ 20 on the strap. Next, after the expanded loop has been located around the package, a higher pressure must be applied to the
overlapped portions to prevent the strap free end 38 from
being drawn out of engagement with weld head 52, during the
! ~ tensioning step. Thus, at this point, solenoid valve 134 is
energized to open port A to provide médium pressure air to
anvil air cylinder actuator 120 to cause the anvil 44 to
exert about 30 to 40 pounds on the strap against the weld
~. 4~ _
head 52. After the tensioning process has been completed,
the solenoid valve 134 is de-energized to close port A.
, ;~ 30 However, since port C is plugged, the cylinder actuator 120
~:
-30-
,. '
~ 1063501
remains pressurized and the anvil 44 remains pressed against
the strap loop.
During the next joint-forming step, the strap must
be held with even more force against the weld head 52 as
the weld head 52 is oscillated at high frequency to form
the friction-fused joint. To accomplish this, the solenoid
valve 136 is energized to open port A to admit higher pres-
sure air to anvil air cylinder actuator 120 to force anvil
44 against the strap and weld head 52 with about 100 pounds
Of force.
The cutter air cylinder actuator 109 is supplied
with high pressure air from high pressure regulator 130 only
through solenoid air valve 136 since check valve 138 pre-
vents air from low and medium pressure regulators 126 and
128 from flowing into the cutter air cylinder actuator 109.
Note that ~olenoid air valve 136 admits air to both the
anvil air cylinder actuator 120 and the cutter air cylinder
; ,:;
actuator 109 simultaneously. However, the action of the
cutter air cylinder actuator 109 is delayed about one-half
second while the high pressure air is admitted to the anvil
air cylinder actuator 120 to hold the strap until comple-
tion of the friction-fusion welding. After the weld is
completed, the cutter air cylinder actuator 109 is permitted
to move the cutter blade to sever the strap. This is accom-
plished by the flow control valve 139 in the air supply line
to cutter air cylinder actuator 109. The flow control valve
.
139 p~ovides a controlled 810W rate of pressurization and,
~ acting through the cutter air cylinder actuator 109, moves
!~.'',~ the cutter blade 102 forward so that it reaches the strap
length 36 (Figure 12) just as the weld sequence is terminated.
-31-
,
:
~ 1063501
After the cutter blade 102 has severed the strap and
reached the full extent of its travel, solenoid valve 136
is de-energized to close port B and solenoid valve 132 i8
de-energized to close port A and open port c to exhaust
air pregsure from both the cutter air cylinder actuator 109
ana the anvil air cylinder actuator 120. The internal
spring return mechanisms in each of the cylinders causes
anvil 44 and cutter blade 102 to return to the fully re-
tracted positions.
ET~CTRICA~ CONTROL 8YSTEM
In order that the ~trap loop be properly formed,
expanded, tensioned, friction-fused, and severed, the se-
quence of operation must be appropriately controlled. The
operation of the apparatus 20 of the present invention can
be made to operate automatically and rapidly by means of a
~uitable electrical control sy~tem. A suitable oontrol sys-
tem is illustrated $n the simplified oontrol block diagram
i l of Figure 14. In the diagram, the neoessary intorlocking
latching relays and switches are omittod. It is assumed
that apparatus is at the beginning of a strapping cycle in
a power-on ready mode with the strap threaded in the guide-
ways 42 up to the cutter block 106. The cup 28 is in the
. ~
rais-d po~ition by the energized solenoid actuator 66.
The solenoid valve 132 is energized to pressurize the anvil
~, cylinder actuator 120 to move the anvil 44 against the cup
28 ~a~ shown in Figure 7) with about 2 pounds of force.
`; The field coils of the traction wheel motor 76 are energized
for motor operation in the direction to feed the strap into
I
the cup 28.
A ~trap feed switch 143 is provided and is pre-
-32-
'
. .
1063501
ferably a foot-operated momentary contact type. When
depressed, the feed switch 143 energizes the armature of
the traction wheel motor 76 to turn the motor in the direc-
tion to feed the strap. The feed switch 143 also actuates
the incremental control unit 74 associated with the traction
wheel shaft 72 to lower the cup 28 after the primary strap
loop is formed. As the cup 28 is lowered, the motor is still
rotating 80 that the strap continues feeding. As the cup
reaches the lower position beneath the surface of the shoul-
der 26, the anvil 44 is urged against the strap to force thestrap against the weld head 52 under the influence of the
low pressure air being supplied to anvil cylinder actuator
through the solenoid valve 132. The anvil 44 bears against
the strap and the weld head 52 with about 2 pounds of force
as the loop continues to expand. Release of the feed switch
143 stops the motor 76 and stops the strap feed. Repressing
of the feed switch 143 continues the feeding of strap and
expansion of the loop.
When the loop is of sufficient size, the operator
releases the feed switch 143. Alternatively, if identically
sized packages are being strapped on a production line
basis the feeding of the strap and expansion of the loop
~; could be controlled by a timer. In any case, the operator
next lifts the loop and places it over the package as
illustrated in Figure 4.
A strap tension switch 148 is provided to reverse
the motor 76 to tension the loop about the package. The
tension switch 148 is preferably a foot-operated momentary
contact type. The tension switch 148 is also connected to
actuate the solenoid valve 134 to admit medium pressure air
-33-
``'
~ : .
~
1063501
to the anvil air cylinder actuator 120 to move the anvil
44 against the strap loop and the weld head 52 with about
40 pounds of force. This holds the strap free end 38
against the weld head 52 while the overlapping portion of
the strap loop is allowed to slide against the anvil 44 as
the loop is tensioned.
When the predetermined strap loop tension level
(about 10 to 15 pounds on small packages) is reached, the
tension sensing switch 100 is actuated to stop the motor
10 76 and rever~e the motor field coils for the next cycle
operation in the feed direction. The tension sensing switch
100 also de-energizes the medium pressure solenoid valve
134 and energizes the solenoid valve 136 supplying the high
pressure to the anvil cylinder actuator 120 and the cutter
air cylinder actuator 109. This causes 1) the anvil actua-
tor 120 to provide the high clamping force (approxlmately
100 pounds) required to hold the overlapped strap portion
of the loop while the friction-fusion joint is made and
2) the cutter actuator 109 to move the cutter blade 102 to
sever the strap after conclusion of the joint weld. The
tension-sensing switch also actuates the weld motor 80 and
the timer 152 which de-energizes the weld motor after the
; weld has been completed ~about 3/4 of a second to 1 second).
The timer 152 also de-energizes the solenoid valve 136
thereby blocking the high pressure air supply and de-ener-
gizes the solenoid valve 132 to exhaust to atmosphere so
that both the cutter air cylinder actuator 109 and the anvil
air cylinder actuator 120 are returned by their internal
spring mechanisms to the positions wherein the cutter
30 blade 120 and the anvil 44 are in the fully retracted posi-
tions.
-34-
` 1063501
To set the apparatus for the next cycle, timer
152 also energizes two additional timers, 154 and 156.
Upon timing out, timer 154 energizes solenoid actuator 66
to raise cup 28 and timer 156 energizes solenoid valve 132
to move the anvil 44 forward to abut the cup 28. Timer 154
is set to provide a certain time period for removal of the
strapped package before raising the cup 28. Timer 156 is
set to provide a period longer than timer 154 to assure
; that the cup 28 will be in the raised position when the
anvil 44 is moved forward.
.; ALTERNATE ENBODINENTS OF APPARATUS FOR EFFECTING THE METHOD
~j OF THE PRESENT INVENTION
,, ~ .
Formation of the strap loop with the apparatus
illustrated in Figures 1 through 14 and heretofore described
involves the use of a movable, circular guide ~cup 28).
The strap loop formation step of the method of the pres~nt
invention can also be performed in a number of other ways.
In each of the embodiments, certain mechan~sms,
though not always illustrated, will be understood to exi~t
and function analogously to those mechanisms heretofore
described for the embodiment illustrated in Figures 1-14.
~ ~ Exa~ples of such mechanisms are the strap tran~port zone
.5:~ : guidos 42, the traction wheel 68, the idler wheel 70, and
; the cutter blade 71, as well as the necessary drive means,
' controls, and support structures. In all of the alternate
:;:
embodiments an anvil and associated slide mechanism are
,~. :
provided ~as schematically illustrated and designated 144
and 146, 244 and 246, 344 and 346, 444 and 446, 544 and 546,
and 644 and 646 in Figures 15-17; 18; 19 and 20; 21;
22-25; and 26-28, respectively). The anvil and slide in
these alternate embodiments are understood to perform the
.
.
-35-
- 1063501
same functions as the anvil 44 and slide 46 of the embodi-
ment illustrated in Figures 1 through ~ and as heretofore
described.
Figures 15 through 17 schematically illustrate
another way of performing the step of forming a primary
strap loop and expanding the strap loop to a larger dia-
meter by use of an alternate, or second embodiment of a
strap loop forming mechanism. The mechanism illustrated
would be used in a strapping apparatus, such as the strap-
ping apparatus 20 illustrated in Figures 1 through 14,
and would be located in the strap loop forming area of the
apparatus (the strap loop forming area of apparatus 20 i8
illustrated in Figures 8-9). Specifically, in place of
the weld head 52, a loop forming wheel 112 is provided and
functions as an inner guide for the length of strap 36 as
the strap free end 38 is fed tangentially with the peri-
meter of the wheel.
, Surrounding the wheel 112, and spaced from it,
are a number of pivotable guide plates 114 which are spring-
biased to a vertical position and provide a strap guide on
the loop exterior side of the length of strap 36. Figure
17 shows one of the pivotable guide plates 114 biased to
the vertical direction by an appropriate spring mechanism
116 and further shows a portion of the strap 36 adjacent
, . ~
one side of the plate 114 as the strap is guided thereagainst.
The guide plates can be of varying size and number. In the
embodiment illustrated, there are four guide plates forming
a roughly polygonal shape, or more specifically, 4/6 of a
hexagon. A fifth side of the hexagon is formed by a sta-
tionary guide plate 115 and a sixth side of the hexagon is
, -36-
~ "
1063S01
formed by a smooth-surfaced pad or anvil 144 which i8
movable towards and away from the wheel 112 by an appro-
priate slide mechanism 146.
During the stage of initial loop formation, the
~A', strap free end 38 is fed into the strap loop forming area
between the wheel 112 and the anvil 144 and is guided by
.. ..
the wheel 112 and the guide plates 114 and 115 to form a
loop therebetween. After the strap has been fed in a circle
slightly greater than 2~ radians to form the loop with a
portion overlapped by the strap free end 38, the anvil 144
. . .
i8 moved closer towards the wheel 112 to apply a predeter-
mined amount of force against the overlapped portions of
the strap loop between the anvil and the wheel 80 that the
overlapped portions are lightly held together. The wheel
112 preferably has a rough peripheral surface for contacting
a side of the strap free end 38. The strap is contlnued to
be fed against the guide plate~ 114 and the ~trap free end
,. ...
38 is restrained, against the wheel 112, from further move-
ment. With an appropriate choice of the strength of the
spring 116 used to bias the guide plates 114 to the vertical
position, the plates 114 will be forced to pivot outwardly
~.~,^ ,. ~ .
and down by the force of the expanding strap loop to assume
the position shown in dashed lines in Figure 17. This will
~ permit the strap loop to expand to a larger size 30 as illus-
's, .
i~ trated in Figure 16.
., ~
When the loop has been expanded to the proper
predetermined size, the strap feeding process i8 terminated.
Next, a package can be located over a portion of the loop
and the loop can be twisted 90 (out of the plane of Figures
15 and 16) to place it around the package for subsequent
, .
; .
,. ..
~ 37
,,"'
1063S01
; tensioning in the manner previously described for the
embodiment illustrated in Figure 4. The wheel 112 may be
relatively small, say between 1 and 2 inches in diameter,
or may be much larger. Regardless, if plastic strap or
plastic-coated metal strap is used, the wheel 112 can be
oscillated with a small angular rotation at a sufficiently
high frequency to form a friction-fused joint in the manner
analogous to that described for the preferred embodiment
.~; of the weld head 52 previously described with reference to
Figures 1 through 14.
Severance of the strap loop from the trailing
length of strap can be effected by a suitable strap sever-
ing mechanism, not illustrated, such as the cutter blade
71 previously described for the preferred embodiment and
j illustrated in Figure 7.
A third embodiment of the strap loop forming
:; mechanism of an apparatus for strapping a package according
: to the method of the present invention is illustrated in
Figure 18 and is similar to the strap loop forming mech-
,: "'" ' 20 anism of the first embodiment illustrated in Figures 1
through 14. A cup 228 is provided to receive the length
of strap 36 and to guide the strap free end 38 on the
inner periphery thereof to form a primary strap loop. A
weld head 252 is provided inside the cup 228 and has a
. , .
lower guide flange 260 to maintain the plane of strap 36 at
the proper elevation within the cup 228. An anvil 244 and
~;. movable slide mechanism 246 are illustrated schematically
and function in a manner anælogous to the anvil 44 and
: ~ movable slide mechanism 46 of the first embodiment illus-
trated in Figures 1 through 14. However, in the case of
,~;, ~, ..
.~., . ~ .
~. -38- :-
6350~ ~
;; ~ ..,
the embodiment illustrated in Pigure 18, the cup 228 is
hinged, or pivotally mounted, on pin 262 for movement to
a tilted position (shown in dashed lines in Figure 18)
after the primary strap loop has been formed. This provides
clearance around the periphery of the primary strap loop to
allow subsequent expansion thereof. The cup 228 is moved
to the tilted position by any suitable drive means or actu-
ator means (not illustrated). With the strap having an
appropriate combination of thickness, width, and flexibility,
any movement or tilting of the cup is not even necessarily
required. That is, the cup, with a properly shaped wall,
could remain stationary after formation of the primary
strap loop. Then continued feeding of the strap into the
cup will cause the strap to buckle out of the cup 80 that
it can expand to a larger size.
Figures 19 and 20 illustrate a fourth ~mbodiment
of the strap loop forming mechanism of an apparatus for
strapping a package according to the method of the present
inv ntion. In this embodiment, a strap loop is formed in
a plane perpendicular to a package support surface 322 on
a strapping apparatus. Initially, the package 324 is placed
upon the package support surface 322 adjacent the loop
forming area. A length of strap 36 is then fed between,
.
and guided by, two axially aligned adjacent guide rings
326 and 328. The guide rings 326 and 328 are pivotally
mounted on pins 330 and 332 respectively, which are mounted
~` in recessed channels 334 and 336, respectively. The guide
p~ ~
rings 326 and 328 can thus be rotated 90 degrees to a
position below, and parallel to, the package support sur-
face 322. To this end, guide ring cavities 338 and 340
. ,: .
.....
~''.' ' .
-39-
.
1063501
are provided to receive the guide rings 326 and 328,
respectively. The strap 36 can be fed into a slot (not
shown) between the guide rings 326 and 328 by an appropriate
traction wheel mechanism.
In a manner analogous to that described for the
embodiment illustrated in Figures 1 through 14, a plastic
strap or plastic coated metal strap can be formed into a
primary strap loop and then gripped between a weld head 352
and an anvil 344 for the subsequent loop expansion, loop
tensioning, and friction fusion steps. In Figure 19, the
anvil 344 is schematically illustrated as being movable
towards and away from the strap 36 and weld head 352 by
slide mechanism 346 and the weld head 352 i8 shown mounted
on shaft 353 and driven by an appropriate drive means or
motor 355.
By appropriate control means, the length of strap
l 36 i~ fed between the guide rings 326 and 328 until a pri-
;j mary strap loop is formed with the strap free end 38 over-
lapping a portion of the loop. At this point, the anvil 344
is urged against the overlapping strap portions and the guide
rings are moved, by a suitable means, to the horizontal
.
position below the package support surface 322 to provide
i. ... .
clearance around the periphery of the loop. The loop is
then expanded by continued feeding of the length of strap
until the desired larger diameter is reached. The package
is then moved into the loop and the loop is subsequently
tightened, tensioned, and severed in a manner similar to
that described for the embodiment illustrated in Figures 1
through 14. However, with the apparatus illustrated in
Figures 19 and 20, the loop does not have to be twisted ~
., :
-40-
~063SO~
90 degrees to be placed around the package since the loop
is formed initially in the plane perpendicular to the pack-
age support surface 322 and since the package 324 can be
placed therein without requiring the loop to be twisted
in any manner.
When the loop is tensioned about the package 324,
the small weld head 352 is necessarily located between the
package and the strap loop which causes the loop to be
slightly larger than the periphery of the package. After
the loop has been tensioned, friction-fused ~or the over-
lapped ends otherwise suitably ~oined), and severed from
the trailing length of strap, the weld head 352 must be
, . . .
removed from between the package and the strap loop. This
can be accomplished by moving the combined assembly of weld
head 352, shaft 353 and motor 355 away from the package (in
a direotion to the right as viewed in Figure 19) by appro-
priate mechanisms (whlch are not illustrated). With very
large packages and with very small weld head diameters,
... .
the creation of a slightly larger diameter loop about the
package resulting from the weld head being disposed between
th loop and the package is negligible. Further, if the
large package was slightly resilient, the package would
;~ expand slightly to a larger diameter (and the strap itself
would contract to a slightly smaller diameter) to effect a
tight loop about the package.
~ Figure 21 illustrates a fifth way of performing
fy~,,, ?~
~, the step of forming a primary strap loop and expanding the
,i~ - strap loop to a larger diameter. The mechanism illustrated
in Figure 21 would be used in a strapping apparatus, such
as the strapping apparatus 20 illustrated in Figures 1
~.~
,.
~ ~ .
-41-
~ 0~;3501
through i4, and would be located in the strap loop forming
area of the apparatus (the strap loop forming area of
apparatus 20 is illustrated in Figures 8-10). Specifically,
in place of the guide cup 28 and the weld head 52 in
apparatus 20, there is provided a flexible guide band 428
and a strap free end stop block 452, respectively. Opposite
the stop block 452 is an anvil 444 which is movable toward
and away from the stop block 452 by a slide mechanism 446.
The length of strap 36 is introduced to the inner periphery
of the flexible guide band 428 between the anvil 444 and
stop block 452. The strap free end 38 18 guided in a circle
by the inner periphery of the flexible guide band 428, and
after traveling in a circle for slightly greater than 2
radians, impinges upon the stop block 4æ thus forming a
primary strap loop with a portion of the loop overlapped
by the strap free end 38.
The flexible guide band 428 can be of any suit-
,
ably flexible material such as polyethylene or rubber, or
even thln metal. In the loop forming position, the band
428 extends from an anchor point 454 in a circular locus
with a free end 455 in abutment with the anvil 444. On
the free end 455 of the flexible guide band i8 a guide pin
or prong 457 which projects from the bottom of the flexible
guide band 428 and into an arcuate slot or track 458 in
the shoulder surface 26 of the apparatus. As illustrated
in Figure 21, the shape of the track 458 is an involute
of the circle formed by the flexible guide band 428 when
the band is in the position illustrated in Figure 21 for
forming the primary strap loop. After the primary strap
loop has been formed, the free end 455 of the band 428 is
,' .
; '
-42-
~0 6 ~ ~
moved in the locus of the track 458. To this end, by
appropriate drive means not illustrated, the pin 457 on
the free end 455 of the band 428 is driven in the track
458 to point B so that the flexible guide band 428 assumes
a substantially straight line orientation illustrated by
dashed lines and labeled 428'. In the straight line orien-
tation, the flexible guide band 428' is thus spaced away
from the formed primary strap loop to provide clearance
; about the periphery of the loop. Next, the anvil 444 is
moved closer towards the loop to apply a relatively small
force against the overlapped portions of the strap loop to
restrain the strap free end 38 from disengaging from the
stop block 452. Subsequently, by appropriate feed drive
means, the length of strap 36 can continue to be fed to
j expand the loop to the desired larger diameter. A package
".. .. .
can then be placed over a portion of the loop and the loop
can be twisted about the package. The loop can then be
ten~ioned and tightened about the package in a manner simi-
`''
lar to that previousl~ described for the embodiment illus-
trated in Figures 1 through 14. The overlapping portions
~i of the strap loop can be joined by appropriate means,
~1 '
;'; such as by a friction-fusion, application of an independent
~,;. .,
' seal, or formation of an interlocking slit joint. Creation
of a friction-fusion joint would require the stop block 452
i, to be oscillated or vibrated sufficiently rapidly to generate
heat by friction and effect interface melting therebetween.
Mechanisms for applying an independent seal or for forming
-i an interlocking slit joint to metal strap would be of a
r
conventional nature and associated with anvil 444 and stop
block 452 as may be necessary or desired.
-43-
`
~ .~ .. .. .
~063501
Figures 22 through 25 illustrate another way
of performing the step for forming a primary strap loop
and expanding the strap loop to a larger diameter by use
of a sixth embodiment of a strap loop forming mechanism.
The mechanism illustrated would be used in a strapping
apparatus, such as the strapping apparatus 20 illustrated
in Figures 1 through 14and previously described. The strap
loop forming mechanism would be located in the strap loop
forming area of the apparatus (the strap loop forming area
of apparatus 20 is illustrated in Figures 8-10).
In this sixth embodiment, a strap guide is not
required. Instead, a wheel 552 is provided ~in place of
the weld head 52 of the first embodiment illustrated in
Figures 8-10) which has a slot 554 for receiving the strap
free end 38 of a length of strap 36. As the strap is fed
by appropriate traction wheel feed means ~not illustrated),
,; the strap free end 38 enters the slot 554, abuts the end of
the slot in the wheel 552 and the wheel is rotated (counter-
clockwise as viewed in Figures 22 to 24). The length of
strap 36 is fed until the wheel 552 has rotated slightly
greater than 2~ radians so that a primary strap loop is
formed with a portion of the loop overlapped by the free
i end 38. After the primary strap loop has been formed, the
wheel 552 can be locked again6t further rotation whlle the
strap length 36 is continued to be fed. An anvil 544 i8
provided adjacent the wheel 552 and is movable toward and
away from the wheel by a slide mechanism 546 (schematically
illustrated in Figures 22 through 25). The anvil 544 is
brought into contact with the exterior side of the length
of strap 36 in the area of the overlapped portion of the
',~ '
-44-
"
,.................................. . ~ :
'' . " ' -.' : ' ' . - ,.,' ' ' ' ~: ,
- - . , ~ . , .
~063501
. .
loop to restrain the strap against movement away from
wheel 552 at that point. With the wheel 552 prevented
from rotating, the primary strap loop expands from around
~ the periphery of the wheel 552 to form a loop 30 of any
-~ desired larger size as illustrated in Figure 24.
With a relatively small wheel 552 and a relatively
~i large package 24, the package 24 can be inserted into the
expanded loop as shown in Figure 25. By means previously
described for the other embodiments, the loop can then be
~;, 10 tensioned about the package. Subseguently, the wheel 552
'1'''' ':'
;- ~ could also function analogously to the weld head 52, des-
crlbed for the embodiment illustrated in Figures 1 through
; 14, by producing a friction-fused joint. Following formation
, ~,
~ of the friction-fused joint, the wheel 552 is withdrawn from
; betweon the package and the loop.
, . ...................................................................... .
Alternatively, instoad of inserting the package
24 into the expanded loop as illustrated in Figure 25,
the expanded loop could be first twisted 90 degrees ~out of
the plane of Figure 25) and the package could then be inserted
into the loop above the wheel 552 and anvil 544. Such a 90
degree twist orientation of the loop is identical to that
effected in the process step performed by the previously
described preferred embodiment and illustrated in Figure 11.
Further, with metal strap, the overlapping por-
tions of the strap loop could be joined by conventional
independent seals or interlocking slit joints, The mech-
.,;
~ anisms for effecting such conventional joints are not
.
~ illustrated in Figure 25 but could be located adjacent the
s;i; ~ wheel 552 and anvil 544 around the overlapped portion of
~ 30 the strap loop.
~ .
~ . , .
~ -45-
,~ '
;'
r - `
~063s0~
A seventh.embodiment of a strap loop forming
mechanism i8 illuætrated in Figures 26 through 28. The
mechanism illustrated therein would be used in a strapping
apparatus, such as the strapping apparatus 20 illustrated
in Figures 1 through 14, and would be located in the strap
loop forming area of the apparatus (the strap loop forming
area of apparatus 20 is illustrated in Figures 8-10).
A substsntially circular guide 628 is provided
in the surface of the apparatus for receiving the length
of strap 36. In place of a weld head (such as weld head
52 illustrated in Figures 6 through 10) a stop block 652
i8 provided near the periphory of the circular guide 628.
Opposite the stop block 652 is an anvil 644 which is mova-
~le toward ~nd away from tho stop block by a slide mechanism
646 which is schematically lllustratod in the Plgures 26 :~
and 27.
,i . .
,: Initially, when the length of strap 36 is fed
into the guide 628, the strap free end 38 passes between
the stop block 652 and the anvil 644 which has been spaced
20 away from the stop block 652 to allow passage therebetween.
The strap free end 38 is then guided around the periphery
of the guide 628 until it has completed a circular motion
of a slightly greater than 2~ radians 80 that a strap loop
is formed with a portion of the loop being overlapped by
strap free end 38 and 80 that the strap free end 38 has
. .~ .
impinged upon stop block 652~
Next, the anvil 644 is moved to press against
the overlapped portion of the loop with a relatively small
~ force and the formed primary strap loop is partially
.,.~ 30 lifted out of the guide 628 to allow expansion of the loop.
.~,.
~ . .
,~ --46--
f~
1063S01
To this end, a liPt lever 650 is provided below the formed
primary strap loop and the bottom of the guide 628. Lift
lever 650 is pivotally mounted on pin 651 below guide 628
; and is pivotally connected on one end to rod 657 which is
,, ,
secured to actuator 659. Actuator 659 moves rod 657 in a
vertical reciprocal tion as viewed in Figure 27 to lower
and raise, respectively, the lift finger 650.
When the lift finger 650 has been raised to the
; ~ position shown in Figure 27, the length of strap 36 can
continue to be fed 80 that the loop 30 expands to any
desired larger diameter as illustrated in Figure 28. A
package to be strapped is then placed over the stop guide
/~ block 652 and anvil 644 and the expanded loop is twisted
upwardly and around the package in a manner analogous to
that for the preferred embodiment illustrated in Figure 11.
~,.....
; Subseguently, the loop can be tew ion~d by a suitable trao-
tion wheel mechanism, such as that described for the pre-
,;,.:
ferred embodiment of the apparatus 20 illustrated in Figures
1 through 14.
After tensioning, a conventional independent seal
or slit joint can be applied to the overlapped portion of
, . ~ .
; i the strap loop by mechanisms not illustrated. Alternately,
~ ~ the stop block 652 could be rapidly oscillated or vibrated
. ,
to effect a friction fusion joint on a plastic or plastic-
coated metal strap. Instead of a stop block 652, a weld
head similar to the weld head 52 illustrated in Figures 6-10,
could be provided. It is not necessary that the strap free
" ~ .
~ end 38 abut a stop block or similar member upon completion
. ~
;~ of forming the primary strap loop. This is because the
strap feeding can be governed by suitable automatic rotation
-47-
~.
.
:
1063501
indexing controls to terminate the feeding of the length
of strap 36 after the primary strap loop has been created
with the desired amount of overlap.
An eighth embodiment of a strap loop forming
mechanism is illustrated in Figures 29 and 30. The mech-
; anism illustrated therein would be u~ed in a strapping
apparatus, such as the strapping apparatus 20 illustrated
in Figures 1 through 14, and would be located in the strap
loop forming area of the apparatus (the strap loop forming
area of apparatus 20 is illustrated in Figures 8-10). This
eighth embodiment is somewhat similar to the fourth embodi-
ment illustrated in Figures 19 and 20 and described above.
In this eighth embodiment, strap guide rings 726 and 728
are pivotally mounted for movement into a cavity 738 below
the package support surface 722. However, the gulde rings
726 and 728 pivot about axes 727 and 729 respectively, which
are perpendicular to the plane of the primary loop fonmation
; whereas the guide rings 326 and 328 of the fourth embodi-
ment pivot about axes that are parallel to the plane of
primary strap loop formation. The guide rings 726 and 728
each have identical cross sections that are substantially
H-shaped. As illustrated for guide ring 728 in Figure 21,
the H-shaped cross section provides an interior channel
comprising sidewalls 731 and 733 and a perpendicular arcuate
guide wall 735, all of which function to contain and guide
the strap as the primary loop is being formed.
!' i . .
Unlike the fourth embodiment, the eighth embodi-
ment does not have a weld head mounted within the central
portion of the guide rings. Rather, an anvil 744 is pivot-
ally mounted about shaft 745 and has 1) a top surface flush
':
-48-
: 1063501
. ' : .
with the package support surface 722 and 2) a strap bearing
surface opposite, and facing, a combination feed/tension/
weld head wheel 752. After completion of the strapping
process, the anvil 744 can be pivoted out from between the -
package and the strap loop by an appropriate actuator and
linkage mechanism 747.
The strap 36 is threaded between the anvil 744
and feed/tension/weld head wheel 752 and is fed by rotation
of the wheel 752 in a clockwise direction (as viewed in
~.
Figure 29) around the inner periphery of the vertically
oriented guide rings 726 and 728 until the strap free end
38 overlaps a portion of the loop. In order for the loop to
be expanded, the guide rinqs 726 and 728 mu~t be pivoted
about axes 727 and 729 respectively, to the lower position
illustrated by dashed lines in Figure 29. This, of course,
provides an unobstructed expansion area around the peri-
meter of the primary loop to allow expansion thereof to
a predetermined larger diameter. The pivotal movement of
the guide rings 726 and 728 is effected by an appropriate
actuator mechanism such as an electric solenoid or air-
operated cylinder actuator 765 connected to linkage members
766, 767, and 769.
As illustrated in Figure 30, wheel 752 is mounted
on shaft 753 to motor 755. Motor 755 is mounted on carriage
.
~ 757 which can move the motor, shaft, and wheel in a vertical
- direction by suitable drive means ~not shown). The weld
head 752 is generally cylindrical and presents a peripheral
strap gripping surface. As the primary loop is being formed,
and during subsequent operations, the weld head 752 is
aligned with the strap 36 as illustrated in Figure 30. By
-49-
1063501
appropriate movement of the carriage 757, the weld head 752
can be impressed upon strap 36 so that the strap free end
38 is maintained in frictional engagement with anvil 744
while strap length 36 can continue to be fed forward into
the guide rings 726 and 728, sliding against the adjacent
strap free end 38, to expand the loop.
After the loop has been expanded, the rotation of
wheel 752 is reversed to tension the loop about a package
that has been inserted therein. If necessary, by appro-
priate upward movement of the carriage 757, a higher force
- can be applied to the overlapping strap lengths 36 and 38
by the wheel 752 during the tensioning process to hold the
strap free end 38 in place.
After the tensioning is complete, a connection can
be formed between the strap free end 38 and the overlapped
strap length 36, such as by friction fusion wherein the
wheel 752 is rapidly oscillated or vibrated to form a fric-
j tion fusion joint on plastic or plastic-coated metal strap.
Alternatively, a friction fusion joint could be formed by
rapidly vibrating the anvil 744. In either ca~e, the fre-
quency and amplitude parameters relating to the formation
of such a joint would be the same as has been described
above under the section entitled ~STRAP LOOP FRICTION
FUSION MECHANISM. n
s It i8 posgible to form a loop that has an over-
lapping joint area different than those discussed so far.
Figure 31 schematically illustrates such a formed primary
strap loop. A length of strap 36 is fed in a closed path
; to form a primary strap loop with a portion of the strap
loop overlapped by the strap free end 38. Note that in
, .. . .
--50--
... : : . : . . .
.~ ' 1063S01
this loop, the surface of the strap which is on the "inside~
of the loop is maintained in an orientation such that, in
- the region of the overlap 812, the "inside~ surfaces of the
~ strap are in a facing relationship. The loop can be thus
~,,
'~$ ~. formed by hand or mechanically (which can include feeding
the ~trap 36 in a closed path to form this type of loop).
Following formation of the primary strap loop, the strap
free end 38 i8 restrained from vement while the standing
length of strap is fed to expand the loop to a predetermined
size. Then a package can be inserted into the expanded loop,
after which the loop is tensioned i~bout the package. The
,:
strap free end 38 is then joined, by appropriate means,
to the overlapped portion of the strap length 36 to form a
connection and secure the loop about the package.
During expansion of the loop, the strap free end
38 may be restrained from movement by pressing it, with a
first member 814, against the overlapped portion to the
., ~
i strap 36 in the region of overlap 812. A second member 816,
opposite the first member and presenting relatively less
sliding resistance to strap movement, is pressed against
,,,,~ ,
;~ the strap 36. Specifically, members 814 and 816 could, for
example, comprise respectively, a weld head and an anvil,
similar to weld head 52 and anvil 44 described for the pre-
' k~ ferred embodiment previou~ly described and illustrated in
Figures 1 through 14. It should be noted that once a loop
such as illustrated in Figure 31 has been expanded, the
overlapping portions can be joined by any appropriate
means, including friction fusion, formation of interlocking
slits, or application of an independent seal. Most impor-
tantly, the joint can be formed, as by members 814 and 816
-51-
~.
`.~
: ` :
1063501 ~
(or other members located adjacent thereto), without
requiring that any member, or portion thereof, be placed
inside the loop between the strap and the package. This
has the advantage of increasing residual tension in the
loop since the loop when tensioned, can be drawn tighter
around the package. Further, it should be noted that the
strap loop does not necessarily have to be "twisted"
to be placed about the package. The loop can be formed
and expanded in one plane and the package then moved per-
pendicular to that plane and into the loop.
The method of the present inven~ion can be
advantageously used with compressible articles, bundles,
or bales. In one case, preformed metal or plastic strap
i~
segments, ~e.g., bale ties) could be stacked and loaded
in a magazine of an appropriate apparatus for sequential
feeding (one at a time) to 1) form an lnitial primary
. '!
strap loop and 2) subsequently form an expanded loop.
Thi~ could be accompll~hed, in part, with apparatus simi-
lar to those described above for the various illustrated
embodiments. After the loop ha~ been expanded to a larger
predetermined size, the overlapping ends of the loop could
be joined by any appropriate means. Next, a compressed
bale could be inserted into the strap loop and allowed to
expand against the strap, thus forming a tied bale.
Alternatively, the formed and joined strap loop could be
removed from the strap loop forming apparatus and placed
; ~: . i i
. "1 around a compressed bale which is then allowed to expand
to form a tied bundle.
Instead of using separate preformed strap segments,
a compressed bale could be tied with a loop formed from a
-52-
.... . . ~ .
. . - . ~ .
` - 1063501
continuous length of strap. Apparatus similar to that
illustrated in Figure~ 1 through 14 could be used to form
an expanded loop. But, instead of tensioning the loop about
the bale, just the joint could be formed in the loop. Then
the compressed bale could be placed in the loop and allowed
to expand to form the tied bale. ~lternatively, the formed
and joined loop could be removed from the apparatus and
then placed around the bale.
With respect to bindinq a compressed bale as
de~cribed above, it is important to note that tension need
not nece~sarily be drawn on the expanded strap loop. With
certain types of bales, it can be sufficient to allow the
compressed bale to expand lnto binding engagemont with a
formed and ~oined strap loop.
~i From the foregoing, it will be obsorvod that
,, .
numorous variations and modifications may be effected
without doparting from the true spirit and scope of the
novel conc-pt of the invention. It is to be understood
that no limitation with respect to the specific apparatus
illustrated herein is intended or should be inferred. It
is, of course, intended to cover by the appended claims
i all such modifications as fall within the scope of the
~. .
l ~ claims.
,:
.. ..
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