U.S. patent number 3,915,077 [Application Number 05/527,524] was granted by the patent office on 1975-10-28 for bag forming apparatus.
Invention is credited to Arnie LaFleur, Lee LaFleur.
United States Patent |
3,915,077 |
LaFleur , et al. |
October 28, 1975 |
Bag forming apparatus
Abstract
A plastic bag forming apparatus through which plastic tubular
stock in a flattened condition is directed. The device includes
guide members for engaging transversely opposed gusset-forming
folds on the stock and heat sealing bars for forming heat sealed
seams between plies of the stock at desired locations to provide a
blank which can be opened into a bag having a reinforced square
bottom.
Inventors: |
LaFleur; Lee (Manistee, MI),
LaFleur; Arnie (Manistee, MI) |
Family
ID: |
24101800 |
Appl.
No.: |
05/527,524 |
Filed: |
November 27, 1974 |
Current U.S.
Class: |
493/194; 156/510;
493/239 |
Current CPC
Class: |
B29C
66/8226 (20130101); B29C 66/004 (20130101); B29C
66/8324 (20130101); B29C 65/745 (20130101); B29C
66/1122 (20130101); B29C 66/43129 (20130101); B29C
66/0044 (20130101); B29C 65/18 (20130101); B29C
66/43121 (20130101); B29C 66/8227 (20130101); B29C
66/8511 (20130101); B29C 66/8122 (20130101); B29C
66/8221 (20130101); B29C 66/8122 (20130101); B29K
2827/18 (20130101); B31B 2155/001 (20170801); Y10T
156/12 (20150115); B29L 2031/7128 (20130101); B31B
2247/00 (20130101); B31B 2155/003 (20170801); B31B
2155/00 (20170801); B31B 2160/20 (20170801) |
Current International
Class: |
B31B
47/04 (20060101); B31B 47/00 (20060101); B31B
37/00 (20060101); B31B 033/02 () |
Field of
Search: |
;93/DIG.1,33H,33R,8R,18,19,20,26,27,35SB ;53/183 ;156/510,583 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lake; Roy
Assistant Examiner: Coan; James F.
Attorney, Agent or Firm: Barnes, Kisselle, Raisch &
Choate
Claims
We claim:
1. Apparatus for forming flattened plastic tubular stock material
having inwardly folded gusseted panels along the opposite
longitudinal edges thereof into bags having a reinforced flat
bottom panel defined by heat sealed seams which comprises, means
for supporting a supply roll of said flattened stock material, a
base having a generally flat supporting surface over which the
leading end of said flattened tube is adapted to be advanced from
said supply roll, a heat sealing mechanism movable vertically
toward and away from said support surface for forming adjacent the
leading end of the flattened tube a straight transverse heat sealed
seam and two diagonal heat sealed seams extending inwardly from
opposite side edges of the stock material to said straight seal, a
guide and feed mechanism on said base which includes a pair of
laterally inwardly extending guides on said base, the lateral inner
longitudinal edges of said guides being spaced apart transversely
and adapted to engage the center fold of each gusseted panel as the
stock material is advanced on said support surface to maintain the
flattened tube in proper alignment with the heat sealing mechanism,
a mechanism for severing said stock material along a line spaced
adjacent and forwardly beyond said straight transversely extending
seam, said guide and feed mechanism also including a longitudinally
reciprocable slide on said base having a portion disposed within
each of said gusseted panels and adapted to engage said straight
seam to advance the flattened tubular stock and means for operating
the apparatus to first lower said heat sealing mechanism to engage
the stock on said support surface and thereby form said heat sealed
seams, sever the stock along said line adjacent and forwardly of
said straight transverse seam, then raise the heat sealing
mechanism and thereafter displace the slide forwardly to engage
said straight transverse seam and advance the stock so that the
leading end thereof is accessible for manual grasping.
2. Apparatus as called for in claim 1 including a separator film of
material to which the plastic tube material does not firmly adhere
when subjected to heat and pressure and means supporting said
separator film between the folded layers of the gusseted panels in
vertical alignment with the mechanism for forming said two diagonal
heat sealed seams.
3. Apparatus as called for in claim 2 including means on said slide
directly adjacent said separator film for engaging said film and
stripping it from the heat sealed diagonal seams.
4. Apparatus as called for in claim 2 including a frame mounted on
said base, said heat sealing mechanism being mounted on said frame
and comprising a heat sealing bar extending transversely straight
across the forward end portion of the frame and a pair of heat
sealing bars extending diagonally rearwardly from said transverse
heat sealing bar in a laterally outward direction.
5. Apparatus as called for in claim 4 wherein said frame is mounted
on said base for vertical movement toward and away from said
support surface and including a knife bar on said frame spaced
forwardly of said transverse heat sealing bar and cooperating with
a shear bar at the forward end of said base for severing the stock
material along a line spaced forwardly of said straight transverse
seam when said frame is lowered.
6. Apparatus as called for in claim 4 wherein said slide includes a
pair of laterally spaced stripper plates and a pair of laterally
spaced pusher feet which are spaced from and forwardly of said
stripper plates, the forward edges of the stripper plates extending
generally diagonally of said support surface and the forward edges
of said pusher feet extending transversely straight across said
support surface, said forward edges of the stripper plates and the
pusher feet being disposed rearwardly of said diagonally extending
and said transverse heat sealing bars, respectively, when the slide
is retracted and forwardly of said respective bars when the slide
is advanced.
7. Apparatus as called for in claim 6 wherein said forward edges of
the pusher feet are located rearwardly of said transverse heat
sealing bar a greater distance than the forward edges of the
stripper plates are located rearwardly of said diagonally extending
heat sealing bars in the retracted position of the slide so that
the forward edges of the stripper plates engage said separator film
at the diagonal heat sealed seams before the forward edges of the
pusher feet engage the transverse heat sealed seam when the slide
is displaced forwardly from its retracted position.
8. Apparatus as called for in claim 7 wherein the forward edges of
the stripper plates are skewed relative to the diagonally extending
heat sealing bars.
9. Apparatus as called for in claim 8 wherein said forward edges of
the stripper plates are angularly inclined toward the diagonally
extending heat sealing bars in a laterally outward direction.
10. Apparatus as called for in claim 1 wherein said guides comprise
a pair of laterally spaced plates fixed on said base and said
longitudinal slide includes a pair of laterally spaced stripper
plates and a pair of laterally spaced pusher feet, said stripper
plates being slidably disposed between said support surface and
said guide plates.
11. Apparatus as called for in claim 10 wherein said guide plates
have forward edges disposed rearwardly of said diagonally extending
heat sealing bars and including flexible separator strips mounted
on said guide plates and extending forwardly beyond said stripper
plates so as to underlie said diagonally extending heat sealing
bars.
12. Apparatus as called for in claim 11 wherein said separator
strips are secured to the top face of said stripper plates.
13. Apparatus as called for in claim 1 including a support frame on
which said sealing mechanism is mounted, said support frame being
mounted for vertical movement toward and away from said base, a
plurality of rotatable cams on said support frame, means for
rotating said cams simultaneously, said base having a cam follower
fixed thereon and cooperating with one of said cams to raise and
lower said support frame, said slide having a cam follower thereon
cooperating with another of said cams to reciprocate said slide
longitudinally on said base.
14. Apparatus as called for in claim 13 wherein said two cams are
inter-related such that when said support frame is raised said
slide is reciprocated forwardly from a retracted to an advanced
position and then rearwardly from said advanced to said retracted
position.
15. Apparatus as called for in claim 14 wherein said slide is
spring-biased in a forward direction and said last-mentioned cam
cooperates with the cam follower on the slide to drive the slide
rearwardly against the bias of the spring.
16. Apparatus as called for in claim 14 including a third cam on
said support frame cooperating with a pressure roller on said base
which is spring biased in a downward direction, said first and
third cams being inter-related such that the pressure roller
engages the third cam to bias the support frame in a downward
direction when the first cam and its associated cam follower
permits the support frame to move downwardly.
17. Apparatus as called for in claim 14 wherein said means for
rotating said cams comprises an electric motor, switch means for
de-energizing said motor and means on one of said cams for
actuating said switch means when the support frame is in the raised
position and said slide has been reciprocated to the retracted
position.
18. Apparatus for forming flattened plastic tubular stock material
having inwardly folded gusseted panels along the opposite
longitudinal edges thereof into bags having a heat sealed seam at
the bottom thereof which comprises, means for supporting a supply
roll of said flattened stock material, a base having a generally
flat support surface over which the leading end of the flattened
tube is adapted to be advanced from the supply roll, a heat sealing
mechanism positioned adjacent the leading end of said base for
forming adjacent the leading end of the flattened tube a heat
sealed seam which extends transversely across the tube, a guide and
feed mechanism on said base which includes a pair of laterally
inwardly extending guides on said base, the lateral inner
longitudinal edges of said guides being spaced apart transversely
and adapted to engage the center fold of each gusseted panel as the
stock material is advanced on said support surface to maintain the
flattened tube in proper alignment with the heat sealing mechanism,
means positioned forwardly beyond said heat sealing mechanism for
severing the stock material along a line spaced adjacent and
forwardly beyond said transverse seam, said guide and feed
mechanism also including a longitudinally reciprocable slide on
said base having a portion disposed within each of said gusseted
panels and adapted when advanced to engage said transverse seam and
thereby advance the flattened tubular stock, and means for
operating said apparatus to first cause the heat sealing mechanism
to engage the stock and thereby form said transversely extending
heat sealed seam, sever the stock along said line adjacent and
forwardly of said transverse seam, and thereafter displace said
slide forwardly from a position rearwardly of said heat sealing
mechanism to engage said transverse seam and advance the stock so
that the leading end thereof is disposed forwardly beyond said
severing means and is accessible for manual grasping.
19. The combination set forth in claim 18 wherein said guides are
mounted on said slide.
20. The combination set forth in claim 19 wherein the portion of
said reciprocable slide adapted to engage said transverse seam
comprises the forward edges of said guides.
Description
This invention relates to an apparatus for forming individual
plastic bags from a continuous roll of flattened tubular stock
material.
While the use of plastic bags for packaging has been growing in
popularity, the storage of such bags, particularly the storage of
various sizes of such bags, has posed a problem from the standpoint
of both the space required to store the bags and the ease of
dispensing such bags.
The present invention has for its object the provision of an
apparatus by means of which plastic bags can be readily formed and
dispensed as needed from a roll of flattened tubular stock
material. Moreover, the apparatus of this invention enables bags of
any selected length to be formed by merely withdrawing the desired
length of stock from the supply roll.
More specifically, the apparatus of the present invention comprises
a mechanism through which tubular stock material from a supply roll
is directed and which, in response to actuation of a suitable
switch after the desired length of stock is withdrawn, severs a
previously formed bag from the supply roll and simultaneously forms
the desired heat sealed seams at the leading end of the stock which
will form the closed or bottom end of the next successive bag.
The present invention is designed to form a bag with a reinforced
square bottom of the type shown in U.S. Pat. No. 3,143,277 wherein
the stock material is in the form of a flattened tubular sleeve
having inwardly extending gusseted panels along the opposite
longitudinal edges thereof.
IN THE DRAWINGS
FIG. 1 is a perspective view illustrating one form of cabinet in
which the apparatus of the present invention is adapted to be
housed;
FIG. 2 is a perspective view of the bag in the flattened condition
as it is dispensed from the apparatus;
FIG. 2A is a sectional view through the bag along line 2A--2A
which, for purposes of illustration, has been slightly
expanded;
FIG. 3 is a perspective view of the bag in the open condition ready
to receive articles to be packaged;
FIGS. 4, 5 and 6 are somewhat diagrammatic views showing the
successive operating sequences of the apparatus;
FIG. 7 is a plan view of the apparatus of the present
invention;
FIG. 8 is a side elevational view of the apparatus of the present
invention with parts broken away;
FIG. 9 is a fragmentary sectional view generally along line 9--9 in
FIG. 7 illustrating the means by which the flattened tubular stock
is guided through the apparatus;
FIG. 10 is a perspective view of the pivoted frame of the apparatus
on which the sequencing cams, the sealing mechanism, and the shear
mechanism are mounted;
FIG. 11 is a perspective view of the reciprocating slide of the
apparatus;
FIG. 12 is a perspective view of the base frame;
FIG. 13 is a plan view of the forward end of the base frame with
the stationary guide removed;
FIG. 14 is a fragmentary sectional view along the line 14--14 in
FIG. 13;
FIG. 15 is a fragmentary view illustrating the manner in which the
slide strips and separates the heat sealed seams between the
gusseted panels and advances the stock to facilitate manual
withdrawal of the desired bag length;
FIG. 16 is a bottom view of a heat sealing mechanism; and
FIG. 17 is an end view of the shear mechanism.
In FIG. 1 there is generally illustrated an upright cabinet 10 on
which a cash register 12 at a checkout counter of a retail
establishment may be mounted. Cabinet 10 has a compartment 14 in
which a supply roll 16 of flattened tubular plastic stock is
rotatably supported. Above compartment 14 the bag-forming mechanism
18 of the present invention is arranged. The finished bag 20 is
arranged to be discharged from the cabinet through a slot 22. The
present invention is directed primarily to the construction and
function of the apparatus 18. As the description proceeds it will
become apparent that cabinet 10 merely houses apparatus 18 and may
differ appreciably from that illustrated.
As pointed out above, the bag adapted to be formed by the present
invention is of the type shown in U.S. Pat. No. 3,143,277; namely,
a bag having a square reinforced bottom panel. The stock material
16 is in the form of a flattened tubular sleeve having top and
bottom panels 24 adapted to form the side panels of the bag and
inwardly extending gusset panels 26 which, when the bag is
assembled, form the end walls of the bag. The gusset panels 26
comprise inwardly folded sections 26a, 26b which terminate in
central fold lines 28 which are spaced apart laterally (FIG. 2A).
The square bottom panel is defined by a heat sealed seam 30
extending straight across one end of the bag blank and diagonal
sealed seams 32 which extend from the side edges of the gusseted
blank inwardly to the straight seam 30. While seam 30 extends
through all of the plies of the blank, the diagonal seals 32 are
actually four in number, two extending between the top panel 24 and
the adjacent gusset panel 26a and the other two extending between
the bottom panel 24 and its adjacent gusset panel 26b. Thus, after
these heat sealed seams are formed and the blank severed from the
supply roll, the blank can be assembled into the bag illustrated in
FIG. 3.
Referring now to FIGS. 7 through 12, the apparatus of this
invention includes a rectangular base frame 34 having a pair of
upstanding brackets 36 on which there is pivotably supported an
upper frame 38. Electrically heated seal-forming bars 37, 39 are
mounted on transversely extending support plates 41 at the forward
end portion of frame 38. Bars 37, 39 have their heat sealing edges
projecting downwardly. As shown in FIG. 16, bar 37 and bars 39 are
positioned to form on the bag the heat sealed seams 30, 32,
respectively. Thus, bar 37 extends transversely straight across the
forward end portion of frame 38 and the two bars 39 extend
diagonally outwardly and rearwardly from bar 37.
Base frame 34 is of generally rectangular shape and has three
transversely extending support plates 40, 42 and 44 mounted on the
top side thereof. Plate 40 extends across the rear end of base
frame 34; plate 44 extends across the front end of base frame 34;
and plate 42 is located approximately midway between plates 40 and
44. Brackets 36 are supported on plate 40. A pair of longitudinally
extending and transversely spaced outer guide bars 46 have their
forward ends mounted on plate 44 and their rear ends mounted on
plate 42. There is also mounted on plate 42 adjacent the rear ends
of guide bars 46 and spaced laterally inwardly thereof a pair of
short inner guide bars 48. Outer guide bars 46 in combination with
the inner guide bars 48 form guideways for receiving and guiding
the side rails 50 of a rectangular slide frame 52 (FIG. 11). A
stripper plate 54 is mounted on each side rail 50. The inner
longitudinal edges 56 of stripper plates 54 are spaced laterally
apart to correspond with the distance d between the center folds 28
of the gusset panels on the tubular stock material as indicated in
FIG. 2A. The forward edges 58 of the stripper plates 54 extend
diagonally rearwardly in a laterally outward direction. Forwardly
of stripper plates 54 there is also mounted on each side rail 50 of
slide 52 a pusher foot 60. The forward edges 62 of these pusher
feet extend transversely of the longitudinal axis of slide 52 and
the rear edges 64 of these pusher feet extend diagonally in a
laterally outward direction. The edges 58 and 64 of the stripper
plates and pusher feet are spaced apart as shown in FIG. 11 to
correspond generally with the orientation of heat sealing bars 37
on frame 38.
Between the forward ends of outer guide bars 46 there is mounted on
plate 44 a plastic pad 66 which forms a platen for the sealing
mechanism. Pad 66 has rubber strips 68 and 70 embedded therein.
Strip 68 extends transversely across the front end of plate 44 and
strips 70 extend diagonally rearwardly thereof in a laterally
outward direction. Strips 68, 70 are located to register in
position with heat sealing bars 37, 39, respectively, on upper
frame 38. The top surface of the entire pad 66 is overlaid with a
film 72 of a material such as Teflon to which the plastic bag stock
will not firmly adhere when it is subjected to heat and pressure to
form the heat sealed seams 30, 32.
Referring to FIG. 12, it will be noted that there is mounted on the
two guide bars 46 a pair of laterally spaced guide plates 74, the
inner edges 76 of which are spaced apart a distance d corresponding
to the distance between the center folds 28 of the plastic tube
stock. The forward edges 78 of guide plates 74 extend diagonally in
a laterally outward and rearward direction. Separator strips 80 are
secured to the forward edge portions of guide plates 74 on the
upper side thereof so as to extend forwardly beyond the forward
edges 78 thereof. Separator strips 80 are formed of a material such
as Teflon to which the plastic bag stock material will not firmly
adhere when a heat sealed seam is formed thereon against the
separator strips.
The slide frame 52 illustrated in FIG. 11 is arranged on base frame
34 with the side rails 50 thereof arranged between the outer and
inner guide bars 46, 48 on base frame 34. When the slide frame is
so arranged on base frame 34 the stripper plates 54 underlie the
guide plates 74 on base frame 34. In the normal retracted position
of slide frame 52 on base frame 34 the diagonal slots 82 between
each stripper plate 54 and its associated pusher foot 60 underlie
the separator strips 80 on guide plates 74 and overlie the rubber
insert strips 70 of the plastic pad 66 on plate 44 at the front end
of base frame 34. Likewise, in the normal retracted position of
slide frame 52, the forward edges 62 of pusher feet 60 are disposed
slightly rearwardly of the rubber insert strip 68 at the forward
end of plastic pad 66. A pair of tension springs 84 extend
rearwardly from the rear ends of outer guide bars 46 to anchoring
lugs 86 at the rear end of each side rail 50. Springs 84 urge slide
frame 52 forwardly on base frame 34.
In the arrangement illustrated the power for operating the
apparatus comprises an electric motor 88 mounted on upper frame 38.
A transverse rod 90 at the rear end of frame 38 is journalled in
brackets 36 so that frame 38 is pivotably supported for movement
toward and away from base frame 34. A sprocket 92 fixed to a rotary
shaft 93 extending transversely of frame 38 is connected by a chain
94 with a drive sprocket 96 on the output shaft of motor 88. Shaft
93 supports a plurality of cams which are arranged in pairs. The
first pair of cams, designated 98, is fixed on shaft 93 inwardly of
the side rails of frame 38. Cams 98 lie in the same vertical plane
as and slightly forwardly of a pair of cam followers 100 supported
on the side rails 50 of slide frame 52. The second pair of cams,
designated 102, on shaft 93 are locates slightly outboard of the
side rails of frame 38 and are located directly above a pair of cam
followers 104 which are mounted on an upwardly extending inverted
U-shaped bracket 106 (FIG. 12) on base frame 34. Semi-circular cams
107 are mounted on the outer faces of cams 102. Cams 107 are
adapted to be engaged by pressure rollers 108 which are also
mounted on bracket 106. Rollers 108 are supported by vertically
slidable studs 110 and are urged downwardly by springs 112. Cam
followers 104 and rollers 108 are adapted to engage diametrically
opposite edge portions of cams 98. On the side rail of frame 38
adjacent one of the cams 102 there is mounted a micro-switch 114
having a forwardly projecting finger 116 which is adapted to be
momentarily tripped by a pin 118 (FIG. 7) projecting laterally
inwardly from the inner face of the adjacent cam 102.
The configuration of the various cams described are such that, when
a manual switch 120 (FIG. 1) on cabinet 10 is actuated, motor 88 is
energized to rotate shaft 93 in the clockwise direction as viewed
in FIGS. 8 and 10. With the motor de-energized frame 38 is in the
elevated position; that is, the high sides of cams 102 are bearing
downwardly upon cam followers 104 as shown in FIG. 8. At the same
time, the radial steps 122 on cams 98 are engaged with cam
followers 100 on slide frame 52 to retain the slide in a retracted
position against the bias of springs 84. When the motor is
energized the radial steps 124 on cams 102 ride over cam followers
104 and cause frame 38 to pivot downwardly while slide 52 is
retained in the retracted position by the radial steps 122 on cams
98. As slide 52 pivots downwardly the pressure rollers 108 engage
cams 107 to maintain the frame in the downwardly pivoted position
for a predetermined period of time (for example, 5 seconds).
Thereafter, as the cams continue to rotate, cam followers 104
engage the heel portions 126 of cams 102 and pressure rollers 108
ride off cams 107 so as to pivot frame 38 upwardly. As frame 38
pivots upwardly the radial steps 122 on cams 98 disengage cam
followers 100 and slide 52 shifts forwardly under the bias of
springs 84. The extent to which slide 52 can shift forwardly is
limited by rubber bumpers 128 at the forward end of base frame 34
which are engaged by the forward ends of the side rails 50 of frame
52. Eventually the cam followers 104 again engage the high sides of
cams 102 to pivot frame 38 upwardly and the radial steps 122 on
cams 98 again engage cam followers 100 to retract the slide until
such time as pin 118 momentarily trips finger 116 to de-energize
motor 88 and thereby retain all of the components in the at rest
position shown in FIG. 8. As indicated previously, when motor 88 is
de-energized between cycles upper frame 38 is in the raised
position and slide 52 is in the retracted position.
When frame 38 is pivoted downwardly a knife blade 130 at the
forward end thereof cooperates with a knife bar 132 at the forward
end of base frame 34 to shear the plastic therebetween across the
full width thereof. Likewise, when slide 52 is in the retracted
position and, more specifically, when frame 38 pivots downwardly,
the heat sealing bars 39 are aligned vertically with slots 82
between stripper plates 54 and pusher feet 60. The forward straight
edges 62 of pushser feet 60 are disposed slightly rearwardly of the
straight transverse heat sealing bar 37.
In operating the machine the plastic stock is threaded through the
apparatus so that the center folds 28 engage and extend around the
inner edges 76 of guide plates 74 and the inner edges 56 of the
underlying stripper plates 54 as shown in FIG. 9. Thus, the lower
panel 24 and gusset panels 26b of stock material are located
between stripper plates 54 and the Teflon film 72 which overlies
the plastic pad 66. The upper panel 24 and gusset panels 26a of
stock material are disposed between guide plates 74 and a sheet of
Teflon 134 which extends across and over the front end portion of
base frame 34. Thus, when upper frame 38 is pivoted downwardly, the
heat sealing bars 37, 39, which are maintained at an elevated
temperature, are pressed down on the vertically stacked layers of
the tubular stock material to form seams 30, 32. Since the heat
sealing bar 37 presses down against the upper and lower plastic
layers between the Teflon sheet 134 and the Teflon film 72, a
continuous seam is formed along the leading edge of the stock. At
the central portion seam 30 is of dual thickness whereas at the
laterally outer portions thereof seam 30 includes four layers of
plastic material by reason of the gusseted panels 26. However, at
slots 82 of slide 52 the two upper layers of the stock are
separated from the two lower layers of stock by the Teflon
separator strips 80 at the forward ends of guide plates 74. Thus,
each heat sealing bar 39 actually forms two vertically registering
seams, one between the two upper layers of the stock at the
gusseted panels and one between the two lower layers of stock at
the gusseted panels.
Referring to FIG. 15, several important features of the present
invention are illustrated. For example, it will be observed that
the forward edges 58 of stripper plates 54 are angularly related to
seams 32 formed by the heat sealing bars 39. More specifically, the
laterally outer portions of edges 58 are spaced closer to seam 32
than the laterally inner portions of edges 58. Likewise, it will be
observed that edges 58, at least at their outer ends, are spaced
rearwardly of the adjacent portion of seam 32 a distance x while
the forward edges 62 of pusher feet 60 are spaced rearwardly of
seam 30 by a greater distance y. Thus, after seams 30, 32 are heat
sealed, slide 52 is shifted forwardly so that edges 58 of stripper
plates 54 progressively strip or peel the heat sealed seams for the
separator strips 80 on guide plates 74. This progressive stripping
action also separates the lower seam 32 from the Teflon film 72 and
the upper seam 32 from the Teflon sheet 134. It will also be
observed from FIG. 15 that after seals 32 have been stripped the
forward edges 62 of pusher feet 60 engage the laterally outer
portions of the straight seam 30 to advance the stock forwardly a
distance corresponding to the amount of forward travel of slide 52.
For example, in FIG. 11 it will be noted that pusher feet 60 extend
forwardly beyond the forward ends of side rails 50 so that when the
forward ends of side rails 50 engage rubber bumpers 128 the forward
edges 52 of pusher feet 60 project forwardly beyond the knife bar
132. This enables the forward end of the stock to be readily
grasped so that the operator can pull the stock forwardly and
extend it an amount corresponding to the desired length of the bag
required before actuating manual switch 120.
The operation of the apparatus can be briefly summarized by
reference to FIGS. 4 through 6. In FIG. 4 the apparatus is shown in
the condition wherein the operator pulls out the desired length of
stock after the heat seals 30, 32 have been formed during the
previous cycle of the apparatus. In this position the upper frame
38 is in the raised position and slide 52 is retracted. At this
point the operator actuates switch 120 so that the upper frame 38
pivots downwardly to form seams 30, 32 at the forward end portion
of the stock within the apparatus and to shear off the desired
length to form the bag 20. As pointed out previously, after the
upper frame 38 has been in the lowered position for approximately
five seconds, it is again elevated by cams 102 and slide 52 is
reciprocated by cams 98 to project the leading end of the stock
with the seals formed thereon outwardly beyond the knife blade
structure.
* * * * *