U.S. patent application number 10/086034 was filed with the patent office on 2003-08-28 for continuous motion sealing apparatus for packaging machine.
Invention is credited to Hopkinson, Brian, Odegard, John C., Sorenson, Richard D., Wilson, David T..
Application Number | 20030159401 10/086034 |
Document ID | / |
Family ID | 27753780 |
Filed Date | 2003-08-28 |
United States Patent
Application |
20030159401 |
Kind Code |
A1 |
Sorenson, Richard D. ; et
al. |
August 28, 2003 |
Continuous motion sealing apparatus for packaging machine
Abstract
A sealing apparatus is especially adapted for a packaging
machine which wraps spaced-apart products with a tubular film. The
apparatus includes a frame which provides a path along which the
products are advanced. A sealing support structure is mounted on
the frame for linear reciprocating movement along the path. A crank
arm is rotatably mounted on the frame for reciprocating the sealing
support structure. Upper and lower sealing dies are mounted on the
sealing support structure for linear movement toward and away from
each other in a direction which is generally perpendicular to the
path.
Inventors: |
Sorenson, Richard D.;
(Sheboygan, WI) ; Odegard, John C.; (Green Bay,
WI) ; Wilson, David T.; (Appleton, WI) ;
Hopkinson, Brian; (Green Bay, WI) |
Correspondence
Address: |
John W. Chestnut
GREEN, BURNS & CRAIN, LTD.
Suite 2500
300 South Wacker Drive
Chicago
IL
60606-4002
US
|
Family ID: |
27753780 |
Appl. No.: |
10/086034 |
Filed: |
February 28, 2002 |
Current U.S.
Class: |
53/374.6 |
Current CPC
Class: |
B65B 59/001 20190501;
B29C 66/83543 20130101; B29C 66/8246 20130101; B29C 66/8224
20130101; B29C 66/849 20130101; B65B 25/146 20130101; B65B 51/30
20130101; B29C 65/38 20130101; B29L 2031/7128 20130101; B65B 59/003
20190501; B29C 66/4312 20130101; B29C 66/8223 20130101; B29C 65/224
20130101; B29C 65/745 20130101; B29C 66/1122 20130101 |
Class at
Publication: |
53/374.6 |
International
Class: |
B65B 051/30 |
Claims
I claim:
1. A sealing apparatus for sealing spaced-apart produts which are
enclosed by a film comprising: a frame, the frame providing a path
along which spaced-apart products can move, a sealing support
structure mounted on the frame for movement along said path, upper
and lower sealing units mounted on the sealing support structure
for movement toward and away from each other in a direction which
is generally perpendicular to said path, means for moving the upper
and lower sealing units toward each other to close the sealing
units whereby a film between the sealing units can be sealed and
for moving the upper and lower sealing units away from each to open
the sealing units, and means for reciprocating the sealing support
along said path between first and second positions.
2. The apparatus of claim 1 in which the sealing support structure
is mounted on the frame for linear reciprocating movement along
said path.
3. The apparatus of claim 2 in which the upper and lower sealing
units are mounted on the sealing support structure for linear
movement toward and away from each other.
4. The apparatus of claim 1 in which the upper and lower sealing
units are mounted on the sealing support structure for linear
movement toward and away from each other.
5. The apparatus of claim 1 in which said means for moving the
upper and lower sealing units includes a servo motor.
6. The apparatus of claim 5 in which the means for moving the upper
and lower sealing units includes a belt drive which is driven by
said servo motor.
7. The apparatus of claim 1 in which said means for reciprocating
the sealing support structure includes a crank arm rotatably
mounted on the frame and a link connecting the crank arm and the
sealing support structure.
8. The apparatus of claim 7 including a servo motor for rotating
the crank arm.
9. The apparatus of claim 7 including a linear bearing between the
sealing support structure and the frame for supporting the sealing
support structure for linear movement along said path.
10. The apparatus of claim 9 including a linear guide on the
sealing support structure, the upper and lower sealing units being
mounted on the linear guide for linear movement toward and away
from each other.
11. The apparatus of claim 7 including a linear guide on the
sealing support structure and linear bearings on the upper and
lower sealing units for supporting the sealing units for linear
movement along said path.
12. The apparatus of claim 1 including a linear guide on the frame
and a linear bearing on the sealing support structure for
supporting the sealing support structure for linear movement along
said path.
13. The apparatus of claim 1 in which said means for reciprocating
the sealing support structure includes a belt drive mounted on the
frame and connected to the sealing support structure.
14. The structure of claim 1 including a linear guide on the frame
which extends in the direction of said path and a linear bearing on
the sealing support structure for supporting the sealing support
structure for linear movement along said path.
15. The apparatus of claim 1 including a pair of linear guides on
the sealing support structure which extend generally
perpendicularly to said path, a pair of bearings on each of the
upper and lower sealing units slidably mounted on the linear guides
for linear movement toward and away from each other.
16. The apparatus of claim 15 including upper and lower cross
members connected to said pair of linear guides, and means for
moving said upper and lower cross members and said linear guides in
a direction which is generally perpendicular to said path.
17. The apparatus of claim 16 in which said linear guides are
slidably mounted in said sealing support structure.
18. The apparatus of claim 18 in which said means for moving
includes a threaded shaft connected to one of the upper and lower
cross members and extending through said sealing support structure
whereby rotation of the threaded shaft moves said upper and lower
cross members and said linear guides relative to said sealing
support structure.
19. The apparatus of claim 16 including upper pulleys rotatably
mounted on the upper cross member and lower pulleys rotatably
mounted on the lower cross member, a pair of drive belts extending
over the upper and lower pulleys, and means for rotating the upper
or lower pulleys to move the drive belts, the upper and lower
sealing units being connected to the drive belts for movement with
the drive belts.
20. The apparatus of claim 15 including upper pulleys rotatably
mounted on the upper cross member and lower pulleys rotatably
mounted on the lower cross member, a pair of drive belts extending
over the upper and lower pulleys, and means for rotating the upper
or lower pulleys to move the drive belts, the upper and lower
sealing units being connected to the drive belts for movement with
the drive belts.
Description
BACKGROUND
[0001] This invention relates to a sealing apparatus and, more
particularly, to a sealing apparatus which is particularly suitable
for a packaging machine in which spaced-apart products are enclosed
by a plastic film.
[0002] The invention is an improvement over the sealing apparatus
which is described in U.S. Pat. No. 5,447,012. The '012 patent
describes a packaging machine for packaging bundles or groups of
products such as rolls of bathroom tissue or paper towels. The
rolls are advanced by a conveyor and pull belts, and groups of
rolls are collated into bundles. The bundles are wrapped by a
plastic film, and the longitudinal edges of the film are lapped and
sealed to form an elongated tube.
[0003] The film is sealed between each pair of adjacent bundles by
a sealing assembly. The sealing assembly simultaneously seals the
trailing end of the exiting bundle and the leading edge of the
incoming bundle.
[0004] U.S. Pat. No. 5,753,067 describes a sealer for a bag
maker-packaging machine. Thermoplastic bag-making material is
formed into a vertical tube, and the tube is sealed by a transverse
sealer. The sealer includes a pair of seal jaws which are mounted
on rotary arms which rotate on shafts. The shafts are moved toward
and away from each other by a turn-buckle mechanism. The seal jaws
thereby move along D-shaped trajectories.
[0005] U.S. Pat. Nos. 5,279,098 and 5,347,795 describe specific
mechanisms for moving the shafts of the rotary arms toward and away
from each other.
SUMMARY OF THE INVENTION
[0006] The invention moves upper and lower sealing dies linearly in
two directions while the products to be sealed move continuously to
provide good speed with fewer moving components. The continuous
motion allows the machine to be run at substantially slower speeds
to accomplish the same rate of production as the intermittent
motion of the prior art, thereby allowing reduced costs for the
same output and improved product control. The design also allows
higher production when the machine is kept running at full constant
speeds, providing a substantially faster rate of production without
increasing cost.
[0007] The sealing dies are mounted on mounting bars which are
guided for linear vertical movement. The dies are moved toward each
other to close against the film for sealing and are moved away from
each other to allow the products to pass between the dies. The die
mounting bars are mounted on a reciprocating frame which is
reciprocated linearly in a direction parallel to the direction in
which products move so that the sealing dies move with the film
during the sealing step.
[0008] The sealing dies are opened and closed by a servo motor so
that the length of the sealing region can be varied automatically.
This offers a significant advantage when running packages of
variable length. The ability to automatically vary the length of
the sealing region offers higher rates of operation when running
shorter packages and reduces the acceleration and deceleration
rates required to return the dies to their initial cycle
positions.
[0009] The opening gap between the upper and lower dies can also be
varied automatically. This offers a significant advantage when
running packages of variable height.
[0010] The opening and closing rates of the sealing dies can be
varied without altering the placement of the dies relative to the
product. This offers a significant advantage when extracting air
from between the packages while closing the dies. Another advantage
of this feature is that the sealing time can be maximized by
quickly opening the dies without altering the horizontal placement
of the dies relative to the product.
DESCRIPTION OF THE DRAWING
[0011] The invention will be explained in conjunction with an
illustrative embodiment shown in the accompanying drawing, in
which
[0012] FIGS. 1A and 1B are fragmentary side elevational views of a
packaging machine which includes a sealing apparatus in accordance
with the invention;
[0013] FIG. 2 is an enlarged side elevational view of the sealing
apparatus;
[0014] FIG. 3 is a top plan view of the sealing apparatus;
[0015] FIGS. 4-12 are perspective views which illustrate the
sequence of steps in a sealing cycle;
[0016] FIGS. 13-21 are side views which correspond to FIGS.
4-12;
[0017] FIG. 22 is a transverse view of the sealing section;
[0018] FIG. 23 is an enlarged fragmentary view of a portion of FIG.
22;
[0019] FIG. 24 is an enlarged fragmentary view of one of the linear
guides and bearings;
[0020] FIG. 25 is a front view of the upper die assembly;
[0021] FIG. 26 is a sectional view taken along the line 26-26 of
FIG. 25;
[0022] FIG. 27 is an enlarged fragmentary view of the right end of
the upper die assembly;
[0023] FIG. 28 is a view similar to FIG. 2 of a modified
embodiment; and
[0024] FIG. 29 illustrates one example of the movement of the upper
sealing die.
DESCRIPTION OF SPECIFIC EMBODIMENT
[0025] FIGS. 1A and 1B illustrate a packaging machine 25 of the
general type which is described in U.S. Pat. No. 5,447,012. The
machine is particularly suitable for packaging bundles of rolls of
bathroom tissue or paper towels.
[0026] The machine 25 includes an infeed choke belt section 26, a
product upender section 27, a product collator section 28, a film
feed/lap seal/girth former section 29, a pull belt section 30, a
sealing section 31, and a discharge section 32. Details of those
sections, except for the collator section and the improvements in
the sealing section, are described in U.S. Pat. No. 5,447,012.
[0027] Referring to FIGS. 2 and 3, the packaging machine 25 groups
rolls 35 of bathroom tissue or paper towels into bundles 36. In
FIG. 3, each bundle includes four rolls across the direction in
which the rolls are advanced and four rolls in the machine
direction. In FIG. 4 each bundle includes two rolls across and six
rolls in the machine direction. Many other configurations are
possible. Rolls can also be stacked on top of each other.
[0028] The bundles are advanced in the direction of the arrow A in
FIGS. 2-21 by conveyors and pull belts. Before reaching the sealing
section 31, the bundles are enclosed by a plastic film 38 (FIGS. 2
and 3). As is well known in the art, the longitudinal edges of the
plastic film are overlapped and sealed to provide an elongated tube
which extends in the direction of the arrow A.
[0029] As will be explained hereinafter, the sealing section 31
cuts and seals the plastic tube between each pair of bundles. In
FIG. 3, the leading end 40 of the bundle 36A has already been
sealed. The plastic tube between the handles 36A and 36B is about
to be cut and sealed to provide a sealed trailing end for bundle
36A and a sealed leading end for bundle 36B.
[0030] Referring to FIGS. 2 and 3, the sealing section or apparatus
31 includes a stationary frame 42 which includes vertical posts
43-46 and horizontal beams 47-52. Driven pull belts 53 and 54 (FIG.
3) for conveying the bundles is mounted on the horizontal
beams.
[0031] A traversing or reciprocating frame 58 is mounted on the
stationary frame 42 for forward and backward linear reciprocating
movement in directions which are parallel to the direction of the
product movement. The reciprocating frame 58 includes a pair of
vertical bars 60 and 61 (FIG. 4) and upper and lower cross bars 62
and 63. Laterally extending brackets 65 and 66 (FIG. 3) are
attached to the vertical bars 60 and 61, and a channel shaped
bearing 68 (FIGS. 2, 22, and 24) is mounted below each of the
brackets. The bearings 68 ride on a linear guides or rails 70 which
are mounted on the horizontal beams 51 and 52 of the stationary
frame.
[0032] In the embodiment illustrated in FIGS. 2 and 3 the frame 58
is reciprocated by a pair of crank arms 72 and 73 which are fixedly
mounted on a shaft 74 which is rotatably mounted on the stationary
frame 42. The shaft 74 is rotated by a servo motor 76 on the
stationary frame. The crank arms 72 and 73 are connected to the
brackets 65 and 66 on the reciprocating frame 58 by links 78 and
79. The ends of the links are pivotally connected to the crank arms
and the brackets.
[0033] FIG. 2 illustrates the reciprocating frame 58 in its most
upstream or left position with respect to the direction A of
product flow. As the shaft 74 rotates 180.degree. from its FIG. 2
position, the crank arms 72 and 73 and the links 78 and 79 move the
frame linearly to the right in the direction of product flow. The
linear movement of the frame is guided by the linear guides 70.
[0034] The stroke or length of movement of the reciprocating frame
is indicated in FIG. 2 by dimension B. The most downstream position
or right position of the frame corresponds to the right end of
dimension B.
[0035] As the shaft 74 continues to rotate from 180.degree. through
360.degree., the crank arms and links move the reciprocating frame
opposite to the direction of product flow to return the frame to
the FIG. 2 position.
[0036] Referring to FIGS. 22 and 23, upper and lower sealing die
assemblies 81 and 82 are attached to mounting bars 83 and 84 which
are attached to upper and lower linear bearings 85 and 86. The
linear bearings 85 and 86 are vertically slidable on vertical
shafts 87 and 88.
[0037] Upper and lower cross members 89 and 90 are clamped to the
vertical shafts 87 and 88. Upper and lower pulleys 91 and 92 are
mounted on cross shafts 93 and 94 which are attached to the cross
members 89 and 90. Right and left drive belts 95 and 96 travel over
the upper and lower pulleys 91 and 92.
[0038] The upper mounting bar 83 is connected to the rear portions
of the drive belts 95 and 96 by clamps 97 (FIG. 23). The lower
mounting bar 84 is connected to the front portions of the drive
belts by clamps 98. The lower cross shaft 94 and the lower pulleys
92 are driven by a servo motor 99.
[0039] The mounting bars 83 and 84 for the sealing dies are mounted
for vertical reciprocating movement on the vertical shafts 87 and
88. When the servo 99 rotates the lower pulleys 92
counterclockwise, the rear loops of the drive belts 95 and 96 move
downward, carrying the upper die 81 downward, while the front loops
of the belts 95 and 96 move upward, carrying the lower die 82
upward. The simultaneous movements close the dies. Rotating the
servo clockwise then opens the dies.
[0040] Referring to FIGS. 25 and 26, the upper die assembly 81
includes a pair of conventional impulse sealing ribbons 120 and 121
and a serrated cut-off knife 1222 mounted between the sealing
ribbons. The sealing ribbon 120 seals the trailing end of the
exiting bundle, and the sealing ribbon 121 seals the leading end of
the incoming bundle. A layer of Teflon.RTM. fabric insulates the
ribbons and prevents molten plastic from adhering to the ribbons. A
pair of film grippers 123 straddle the sealing ribbons and are
resiliently biased by gripper springs 124. As the upper and lower
dies close, the film grippers grip the film, the knife 122 cuts the
film, and the sealing ribbons seal the film.
[0041] In one specific embodiment the servo motor 99 was a 71 in-lb
(8 Nm) A/C servo motor which included a 20:1 planetary gear
box.
[0042] The servo motor 99 adjusts the open dimension between dies
to accommodate format height changes. The closed location of the
dies is adjustable by a hand wheel 100 (FIG. 22). The cross members
89 and 90 and the vertical shafts 87 and 88 form a vertically
movable assembly which includes the pulleys 91 and 93, drive belts
95 and 96, and mounting bars 82 and 83. The handwheel 100 is
threadedly connected to a threaded shaft 101. The threaded shaft
passes through upper beam 62 and is rotatably connected to the
cross member 89. When the hand wheel is rotated, the threaded shaft
101 moves the vertically movable assembly up or down as indicated
by the arrows 102. The vertical shafts 87 and 88 slide within
linear guides 103 and 104 on the upper and lower beams 62 and 63 to
permit the up and down movement of the vertically movable
assembly.
[0043] The hand wheel is used to raise or lower the sealing die
assembly so that when the dies are closed, they are at half the
height of the product to be sealed, or at the center of the
package.
[0044] The threaded shaft can also be rotated by a servo motor or
other mechanical or electrical driving means. Further, the
vertically movable assembly could be raised or lowered by
mechanisms other than a threaded shaft, for example, a belt
drive.
[0045] The reciprocating die frame 58 reciprocates horizontally,
propelled by the crank arms 72 and 73 to match the speed of the
plastic film while severing and sealing the film tube. The crank
arms 72 and 73 advantageously provide two pivot locations 105 and
106 (FIG. 2) for the crank arms 72 and 73 to change the amount of
horizontal die movement. In one specific embodiment the two pivot
locations provided 12 inches and 16 inches of horizontal die
movement. The pivot location is set manually depending on the
product format.
[0046] One alternative method of reciprocating the die frame 58 is
illustrated in FIG. 28. The reciprocating die frame 58 is attached
to a belt drive 107 which travels over pulleys 108 and 109. The
pulley 108 is driven by servo motor 76. Rotation of the belt drive
in one direction moves the reciprocating die frame to the right,
and rotation of the belt drive in the opposite direction moves the
die frame to the left.
[0047] In one specific embodiment the servo motor 76 for the crank
mechanism was a 105 in-lb (12 Nm) A/C servo motor driving the die
crank mechanism through a 50:1 gear box. The servo motors and pull
belts were controlled by a controller 111 (FIG. 2), such as a
Giddings & Lewis MMC4PC with a remote I/O.
[0048] FIGS. 4 and 13 illustrate the first step in the sealing
cycle. The leading end of the exiting bundle 36A has already been
sealed. The upper and lower die mounting bars 83 and 84 are in
their open positions to allow the exiting bundle 36A to move past
the sealing dies. As described in U.S. Pat. No. 5,447,012, the
movement of the bundles is controlled by pull belts which are
entrained over upper and lower rollers 110-115. Side pull belts may
also be used. The crank arms 72 and 73 are positioned so that the
reciprocating frame 58 is at the beginning of its forward movement
in the direction A of product movement.
[0049] FIGS. 5 and 14 illustrate the sealing dies in the process of
closing between bundles 36A and 36B. As the dies move toward each
other, the reciprocating frame 58 is moved forwardly by the crank
arms 72 and 73. The rate at which the dies are closed can be varied
to allow the incoming bundle 36B to collapse the gap with the
existing bundle 36A. The rate of die closing is coordinated with
the rate of the die traverse for optimal sealing and end gussets.
The discharge pull belt assemblies and side discharge pull belt
assemblies can be separated in order to release the bundles
contained therebetween so that the downward movement of the sealing
dies against the plastic film tube can collapse the film tube and
move adjacent bundles together. Alternatively, the discharge pull
belts could be driven in reverse to accomplish the same results, or
the bundle can be allowed to slide across the discharge pull belt
on rollers 110 and 111 as the dies close.
[0050] As described in U.S. Pat. No. 5,447,012, gusset plates form
gussets in the sides of the plastic tube as the tube is collapsed
by the sealing dies, and a vacuum lance evacuates the tube before
it is sealed as described in U.S. Pat. No. 6,050,056. Mechanical
tuckers 117 (FIG. 22) can be used to assist the forming of the
gussets on large packages. FIGS. 6 and 15 illustrate the sealing
dies in the closed position at the start of the sealing step. The
plastic tube is clamped between the sealing dies so that the
sealing ribbons can begin sealing the plastic. The cut-off knife
severs the plastic between the spaced-apart sealing ribbons.
[0051] FIGS. 7 and 16 illustrate the end of the sealing step. The
sealing dies remain clamped against the plastic film as the crank
arms 72 and 73 move the reciprocating frame 58 downstream at the
same speed as the speed at which the plastic film is advanced. The
horizontal movement of the sealing dies with the plastic film
provides sufficient time for the sealing dies to seal the film.
[0052] FIGS. 8 and 17 illustrate the opening of the dies toward the
end of the forward movement of the reciprocating frame 58. The
sealing dies are opened to permit the reverse movement of the
reciprocating frame 58 past the second bundle 36B.
[0053] FIGS. 9 and 18 illustrate the reciprocating frame 58 at the
end of its forward stroke. The sealing dies are open, and continued
rotation of the crank arms 72 and 73 will begin the backward motion
of the reciprocating frame.
[0054] FIGS. 10 and 19 illustrate the reciprocating frame in the
process of returning to its original position. The sealing dies
remain open.
[0055] FIGS. 11 and 20 illustrate the reciprocating frame 58 near
the end of its reverse stroke. The sealing dies are beginning to
close as soon as they clear the exiting bundle 36B.
[0056] FIGS. 12 and 21 correspond to FIGS. 4 and 13 and illustrate
the reciprocating frame 58 at the end of its reverse stroke and at
the beginning of its forward stroke. The sealing dies are in the
process of closing.
[0057] FIG. 29 illustrates one example of the path P of the
movement of the upper sealing die which is caused by the
combination of the linear horizontal reciprocating movement of the
reciprocating frame 58 and the linear vertical reciprocating
movement of the mounting bar 83. The same path P is superimposed on
FIG. 2. The path of movement of the lower sealing die is the mirror
image of the path P of FIG. 29.
[0058] Position 204 on path P corresponds to FIG. 4. The sealing
dies are open, and the reciprocating frame 58 is in its FIG. 2
position.
[0059] The curved portion 205 of path P represents the movement of
the upper sealing die as the sealing apparatus moves from its FIG.
4 position to its FIG. 6 position. The upper and lower sealing dies
move toward each other as the reciprocating frame moves to the
right.
[0060] Position 206 corresponds to FIG. 6. The dies are closed
against the plastic film and the sealing portion of the cycle
begins. Sealing continues until point 207, which corresponds to
FIG. 7.
[0061] Between points 207 and 208, the dies open as the
reciprocating frame continues to move to the right. At point 208,
corresponding to FIG. 8, the dies are fully open.
[0062] Between points 208 and 209, the reciprocating frame 58 moves
to the left to return the sealing dies toward their starting
positions. Between points 209 and 204, the sealing dies begin to
close as the reciprocating frame moves to its most upstream
position.
[0063] In the preferred embodiments, the reciprocating frame 58 is
reciprocated by a crank mechanism or by a belt drive. However,
other means can be used for moving the frame back and forth along
the path on which the products move.
[0064] Similarly, the preferred means for opening and closing the
sealing dies includes belt drives. However, other means can be
used.
[0065] While in the foregoing specification a detailed description
of a specific embodiment of the invention was set forth, it will be
understood that many of the details hereingiven may be varied
considerably by those skilled in the art without departing from the
spirit and scope of the invention.
* * * * *