U.S. patent application number 13/398575 was filed with the patent office on 2012-08-16 for packaging machine.
This patent application is currently assigned to ISHIDA CO., LTD.. Invention is credited to Makoto ICHIKAWA, Masashi KONDO, Hideshi MIYAMOTO.
Application Number | 20120204515 13/398575 |
Document ID | / |
Family ID | 45655970 |
Filed Date | 2012-08-16 |
United States Patent
Application |
20120204515 |
Kind Code |
A1 |
MIYAMOTO; Hideshi ; et
al. |
August 16, 2012 |
PACKAGING MACHINE
Abstract
In a packaging machine, a pair of shutter members holds a
tubular film therebetween and shake the tubular film. Articles on
an upstream side of the shutter members within the tubular film
therefore aggregate toward the side of the shutter members while
the vibration of the shutter members causes the gaps between the
packaged articles to be filled. Since the packaged articles
aggregate by inertia due to the vibration, fragmentation thereof is
less likely than in a case in which the packaged articles are
compressed by direct contact. Merely by the movement of rollers on
a waved surface of a shutter cam, the shutter members are shaken in
accordance with the waved surface.
Inventors: |
MIYAMOTO; Hideshi; (Ritto,
JP) ; KONDO; Masashi; (Ritto, JP) ; ICHIKAWA;
Makoto; (Ritto, JP) |
Assignee: |
ISHIDA CO., LTD.
Kyoto
JP
|
Family ID: |
45655970 |
Appl. No.: |
13/398575 |
Filed: |
February 16, 2012 |
Current U.S.
Class: |
53/266.1 |
Current CPC
Class: |
B65B 9/2007 20130101;
B65B 1/32 20130101; B65B 1/22 20130101; B65B 9/2028 20130101; B65B
9/213 20130101 |
Class at
Publication: |
53/266.1 |
International
Class: |
B65B 3/00 20060101
B65B003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 16, 2011 |
JP |
2011-030642 |
Claims
1. A packaging machine that drops articles into a packaging
material formed in a tubular shape and seals the packaging material
making a bag with the articles packaged therein, said packaging
machine comprising: a pair of sealing jaws that selectively hold
the packaging material therebetween in a direction intersecting a
conveyance direction of the packaging material and that selectively
seal the packaging material; and a pair of shutters that
selectively hold the packaging material therebetween in a direction
intersecting the conveyance direction and temporarily impeding
advancement of the packaged articles, the shutters operating in
synchronization with operation of the sealing jaws such that the
shutters hold the packaging material prior to holding and sealing
by the sealing jaws; wherein upon the shutters holding the
packaging material therebetween, the shutters advance a first
distance in the conveyance direction, and further advance a second
distance in the conveyance direction while shaking the packaging
material in the state in which the packaging material is held
therebetween.
2. The packaging machine according to claim 1, further comprising a
cam that contacts and guides a portion of the shutters such that
the shutters move in accordance with a predetermined path defined
by surface contours of the cam.
3. The packaging machine according to claim 2, wherein the cam
includes a flat surface section and an undulated surface section
that contact the portion of the shutters thereby defining the
predetermined path along the conveyance direction.
4. The packaging machine according to claim 1, wherein said
shutters are coil springs.
5. The packaging machine according to claim 2, wherein the portions
of the shutters that contact the cam are rollers.
6. The packaging machine according to claim 1, wherein the sealing
jaws seal the packaging material while the shutters are advancing
the first distance.
Description
TECHNICAL FIELD
[0001] The present invention relates to a packaging machine, and
particularly relates to a packaging machine in which a conveyed
packaging material is formed into a tubular shape, articles are
dropped into the tubular shape, and the packaging material is then
laterally sealed with the articles packaged therein.
BACKGROUND ART
[0002] Vertical packaging machines are common as devices for
packaging food products or other packaged articles by
simultaneously manufacturing bags and loading packaged articles
into the bags.
[0003] In the pillow packaging machine disclosed in Japanese
Laid-open Patent Publication No. 2004-142806, a sheet packaging
material is formed into a tubular shape by a former and a tube. A
vertical joint of the tubular packaging material is vertically
sealed by a vertical sealing means. The article is then loaded into
the tubular packaging material, and a lateral seal is performed
across the top part of the bag and the bottom part of the
succeeding bag by a lateral sealing mechanism. The center of the
laterally sealed portion is cut by a cutter.
SUMMARY OF THE INVENTION
Problems that the Invention is Intended to Solve
[0004] In packaging machines such as the one described above, the
bag size must be reduced and the fill ratio increased in order to
reduce packaging material cost and transportation cost. However,
increasing the fill ratio leads to the risk of the packaged article
fragmenting or becoming trapped in the sealed portion.
[0005] An object of the present invention is to provide a packaging
machine whereby packaged articles can be prevented from fragmenting
and becoming trapped in the sealed portion, and the fill ratio of
packaged articles can be increased.
Means for Solving the Problems
[0006] A packaging machine according to a first aspect of the
present invention is a packaging machine that drops articles into a
packaging material formed in a tubular shape and that seals the
packaging material making a bag. The packaging machine includes a
pair of sealing jaws and a pair of shutters. The pair of sealing
jaws selectively holds the packaging material therebetween in a
direction intersecting the conveyance direction of the packaging
material and selectively seals the packaging material. The pair of
shutters selectively holds the packaging material therebetween in a
direction intersecting the conveyance direction and temporarily
impedes the advancement of the packaged articles. The shutters
operate in synchronization with operation of the sealing jaws such
that the shutters hold the packaging material prior to holding and
sealing by the sealing jaws. Upon the shutters holding the
packaging material therebetween, the shutters advance a first
distance in the conveyance direction, and further advance a second
distance in the conveyance direction while shaking the packaging
material in the state in which the packaging material is held
therebetween.
[0007] In this packaging machine, since the shutters hold the
packaging material therebetween and shake the packaging material,
the packaged articles on the upstream side of the shutters
aggregate toward the shutter side while the vibration of the
shutters causes the gaps between the packaged articles to be
filled. Since the packaged articles aggregate by inertia due to the
vibration, fragmentation thereof is less likely than in a case in
which the packaged articles are compressed by direct contact.
[0008] A packaging machine according to a second aspect of the
present invention is the packaging machine according to the first
aspect, further comprising a cam for contacting and guiding a
portion of the shutters in a predetermined path. A flat surface and
a waved surface are formed in order in the conveyance direction on
a surface of the cam.
[0009] In this packaging machine, merely by the movement of a
portion of the shutters on the waved surface of the cam, the
shutters are shaken in accordance with the waved pattern. This
configuration is achieved by a simple mechanism, and the ability to
easily change the pattern of shaking by changing the waves on the
cam surface gives the design a high degree of freedom.
[0010] A packaging machine according to a third aspect of the
present invention is the packaging machine according to the first
aspect, wherein the shutters are coil springs.
[0011] In this packaging machine, since the pair of shutters
descends while holding the packaging material therebetween and
shaking, the inertial force at reversal of the shaking direction
acts in the direction in which the shutters open. However, the
shutters are coil springs and therefore flex in response to the
acting inertial force, and the shaking is kept from enlarging the
gap between the shutters.
[0012] A packaging machine according to a fourth aspect of the
present invention is the packaging machine according to the second
or third aspect, wherein portions of the shutters that contact the
cam are rollers.
[0013] There is a risk of noise or abrasion at the portion that
contacts the cam surface when the speed at which the shutters
descend increases, but in this packaging machine, contact via
rollers suppresses noise and abrasion.
[0014] A packaging machine according to a fifth aspect of the
present invention is the packaging machine according to any of the
first through third aspects, wherein the sealing jaws seal the
packaging material while the shutters are advancing the first
distance.
[0015] In this packaging machine, since sealing is performed before
the shutters begin shaking, fragments of the packaged articles are
prevented from becoming trapped in the sealed portion even when
fragments drop from the gap between the shutters after the shutters
begin shaking.
Advantageous Effects of Invention
[0016] In the packaging machine of the present invention, since the
shutters hold the packaging material therebetween and shake the
packaging material, the packaged articles on the upstream side of
the shutters aggregate toward the shutter side while the vibration
of the shutters causes the gaps between the packaged articles to be
filled. Since the packaged articles aggregate by inertia due to the
vibration, fragmentation thereof is less likely than in a case in
which the packaged articles are compressed by direct contact.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a perspective view showing a packaging machine
according to an embodiment of the present invention.
[0018] FIG. 2 is a perspective view showing the overall
configuration of a bag-making and packaging unit of the packaging
machine.
[0019] FIG. 3 is a perspective view showing a vibration-imparting
mechanism of the packaging machine.
[0020] FIG. 4A is a side view showing a shutter mechanism of the
packaging machine immediately before a first state.
[0021] FIG. 4B is a side view showing the shutter mechanism in the
first state.
[0022] FIG. 4C is a side view showing the shutter mechanism in a
second state.
[0023] FIG. 5 is a side view showing a lateral sealing mechanism of
the packaging machine, the lateral sealing mechanism including
sealing jaws.
[0024] FIG. 6 is a side view showing a trajectory of the sealing
jaws.
[0025] FIG. 7 is a plan view showing the area around the sealing
jaws.
[0026] FIG. 8 is an external perspective view showing a lateral
drive mechanism of the sealing jaws.
[0027] FIG. 9 is a chart showing synchronization of movements of
the packaging machine, with the periods of discharge of the
products, opening and closing of brushes of the vibration-imparting
mechanism, opening and closing of the shutter mechanism, and
opening and closing of the sealing jaws being depicted
graphically.
[0028] FIG. 10 is a side view showing a shutter mechanism in a
first state in the packaging machine in accordance with a second
embodiment.
DESCRIPTION OF EMBODIMENT
[0029] Embodiments of the present invention are described below
with reference to the accompanying drawings. The embodiments
described below are specific examples of the present invention and
do not limit the technical scope of the present invention.
[0030] (1) Configuration of the Packaging Machine 1
[0031] FIG. 1 is a perspective view showing a packaging machine
according to an embodiment of the present invention. FIG. 2 is a
perspective view showing the overall configuration of a bag-making
and packaging unit of the packaging machine. In FIGS. 1 and 2, the
packaging machine 1 is provided with a combination weighing device
2, a bag-making and packaging unit 5, and a film feeding unit
6.
[0032] The combination weighing device 2 weighs a packaged article
and discharges a predetermined total weight thereof. The bag-making
and packaging unit 5 is a main component for packing the packaged
articles into bags. The film feeding unit 6 feeds a film F for
forming bags to the bag-making and packaging unit 5.
[0033] Operating switches 7 are provided on a front surface of the
bag-making and packaging unit 5. A touch-panel display 8 for
displaying operating states is positioned so as to be visible to a
worker operating the operating switches 7.
[0034] The combination weighing device 2, the bag-making and
packaging unit 5, and the film feeding unit 6 are controlled in
accordance with operations and settings inputted from the operating
switches 7 and the touch-panel display 8. The operating switches 7
and the touch-panel display 8 are connected to a controller (not
shown in the drawings) composed of a CPU, ROM, RAM, and other
components, and the controller takes in necessary information from
various sensors provided to the combination weighing device 2 and
the bag-making and packaging unit 5 and uses the information in
various types of control.
[0035] (2) Detailed Configuration
[0036] (2-1) Combination Weighing Device 2
[0037] The combination weighing device 2 is disposed on top of the
bag-making and packaging unit 5, and after products C are weighed
in a weighing hopper, the combination weighing device 2 combines
the weighed values to achieve a predetermined total weight and
sequentially discharges the products.
[0038] (2-2) Film Feeding Unit 6
[0039] The film feeding unit 6 is a unit for feeding a sheet film F
to a forming mechanism 13 of the bag-making and packaging unit 5,
and is provided adjacent to the bag-making and packaging unit 5. A
roll on which the film F is wound is set in the film feeding unit
6, and the film F is unwound from the roll.
[0040] (2-3) Bag-Making and Packaging Unit 5
[0041] The bag-making and packaging unit 5 is composed of the
forming mechanism 13, a pull-down belt mechanism 14, a vertical
sealing mechanism 15, a shutter mechanism 16, a lateral sealing
mechanism 17, a vibration-imparting mechanism 19, and a lateral
drive mechanism 55.
[0042] The forming mechanism 13 forms the film F conveyed in the
form of a sheet into a tubular shape. The pull-down belt mechanism
14 conveys the tubular film F (hereinafter referred to as the
tubular film Fm) downward. The vertical sealing mechanism 15 seals
overlapping portions (joints) of the tubular film Fm in the
vertical direction.
[0043] The shutter mechanism 16 holds the top part of the tubular
film Fm therebetween to prevent the packaged article from being
trapped in the sealed part before the sealed part is sealed by the
lateral sealing mechanism 17, and the shutter mechanism 16
oscillates with the tubular film Fm in the clamped state.
[0044] The lateral sealing mechanism 17 seals the top and bottom
ends of the bag closed by sealing the tubular film Fm in the
lateral direction. The vibration-imparting mechanism 19 imparts
vibration to the tubular film Fm. The lateral drive mechanism 55
causes the shutter mechanism 16 and the lateral sealing mechanism
17 to move in reciprocating fashion.
[0045] These mechanisms are supported by a support frame 12. The
area surrounding the support frame 12 is covered by a casing 9.
[0046] (2-3-1) Forming Mechanism 13
[0047] The forming mechanism 13 has a former 13a and a tube 13b,
and the combination of these two is generally referred to as a
former. The tube 13b is a member extending in the vertical
direction, a portion of the tube 13b being formed in a tubular
shape, and the top and bottom ends thereof are open. The products C
weighed by the combination weighing device 2 are placed in the
opening at the top end of the tube 13b. The former 13a is provided
so as to surround the tube 13b. The sheet film F unwound from the
film roll is formed into a tubular shape as the sheet film F passes
between the former 13a and the tube 13b. The former 13a and tube
13b of the forming mechanism 13 can be replaced according to the
size of the bags to be manufactured.
[0048] (2-3-2) Pull-Down Belt Mechanism 14
[0049] As shown in FIG. 2, the pull-down belt mechanism 14 is a
mechanism for adhering to the tubular film Fm wrapped around the
tube 13b and continuously conveying the tubular film Fm downward,
and is provided with belts 14c on the left and right sides of the
tube 13b. In the pull-down belt mechanism 14, belts 14c having
adhesive capability are rotated by drive rollers 14a and following
rollers 14b, and the tubular film Fm is thereby carried downward.
In FIG. 2, a roller drive motor for rotating the drive rollers 14a
and the like are not shown.
[0050] (2-3-3) Vertical Sealing Mechanism 15
[0051] The vertical sealing mechanism 15 is a mechanism for
vertically sealing the overlapping portion of the tubular film Fm
wrapped around the tube 13b by heating the overlapping portion
while pushing the overlapping portion against the tube 13b with a
certain pressure. The vertical sealing mechanism 15 is positioned
in front of the tube 13b, and has a heater and a heater belt that
is heated by the heater and placed in contact with the overlapping
portion of the tubular film Fm. The vertical sealing mechanism 15
is also provided with a drive device (not shown in the drawings)
for moving the heater belt toward and away from the tube 13b.
[0052] (2-3-4) Vibration-Imparting Mechanism 19
[0053] As shown in FIG. 2, the vibration-imparting mechanism 19 is
positioned above the shutter mechanism 16 and the lateral sealing
mechanism 17. FIG. 3 is a perspective view showing the
vibration-imparting mechanism. In FIG. 3, the vibration-imparting
mechanism 19 is composed of a pair of cylindrical brushes 191, a
motor 193 for rotating the brushes 191, and an air cylinder 195 for
moving the brushes 191 horizontally.
[0054] The pair of brushes 191 face each other and hold the tubular
film Fm therebetween. The brushes 191 are formed by embedding resin
bristles 191b in a cylindrical core 191a. The core 191a is attached
to a rotary shaft of the motor 193 via a joint 192. Each of the
brushes 191 defines a central axis. The rotary shaft of the motor
193 defines a rotational axis. The brushes 191 are attached so that
the rotary shaft of the motor 193 (the rotational axis) and the
central axis of the core 191a are spaced apart from one another by
a predetermined distance, and the pair of brushes 191 are rotated
by the driving of the motor 193 while being moved toward or apart
from each other. Since the brushes 191 and the tubular film Fm are
in contact with each other, the tubular film Fm is vibrated by the
rotation of the brushes 191.
[0055] The air cylinder 195 moves the brushes 191 and the motor 193
integrally with each other. The pair of brushes 191 can be moved by
the air cylinder 195 in repeated reciprocal motion so as to
alternate between moving toward each other in the direction of
holding the tubular film Fm therebetween and moving in the
direction away from each other.
[0056] The predetermined quantity of packaged articles dropped from
above the tube 13b generally passes into the tubular film Fm as a
vertical stream, and is therefore prone to become bulky in the
vertical direction. However, when the packaged articles are dropped
while the tubular film Fm is being held between the brushes 191,
the advancement of the leading end of the vertical stream of
packaged articles is impeded, and the distance between the leading
end and the trailing end is reduced. The vibration created by the
rotation of the brushes 191 is also transmitted to the packaged
articles, the gaps between packaged articles are filled, and an
aggregation is formed in which the occupied space is further
reduced.
[0057] Since the rotation and reciprocal movement of the brushes
191 creates a rotation which sends articles in the conveyance
direction while vibrating the point of contact of the brushes 191
and the tubular film Fm, the articles are sent toward the lateral
sealing mechanism 17 when the brushes 191 move apart from each
other.
[0058] (2-3-5) Shutter Mechanism 16
[0059] The shutter mechanism 16 holds the top of the sealed portion
of the tubular film Fm therebetween immediately in front of the
lateral seal and stops the packaged articles so that packaged
articles or fragments thereof are not trapped in the seal part
during lateral sealing of the tubular film Fm. The shutter
mechanism 16 repeatedly alternates between a first state of holding
the tubular film Fm therebetween and descending, and a second state
of moving away from the tubular film Fm until again holding the
tubular film Fm therebetween.
[0060] FIG. 4A is a side view showing the shutter mechanism
immediately before the first state. FIG. 4B is a side view showing
the shutter mechanism in the first state. FIG. 4C is a side view
showing the shutter mechanism in the second state. In FIGS. 4A, 4B,
and 4C, sealing jaws are indicated by dashed-dotted lines to
facilitate understanding of the relationship between the shutter
mechanism 16 and the lateral sealing mechanism 17.
[0061] As shown in FIG. 4A, the shutter mechanism 16 is composed of
a shutter cam 170 and a pair of mechanisms 160 which move along a
cam surface of the shutter cam 170. The mechanisms 160 are each
composed of a supporting member 161, a linking member 163, a roller
165, a shutter member 167, and a spring member 169.
[0062] The shutter cam 170 has a cam surface 171 which includes a
flat surface 171a and a waved surface 171b, over which the roller
165 is driven.
[0063] The supporting members 161 are members for supporting
sealing jaws 51a, 51b, and the supporting members 161 also support
the linking members 163 so as to allow the linking member 163 to
rotate.
[0064] In each linking member 163, a long link 163a and a short
link 163b are connected in a V shape, and a connecting part 163c
thereof is rotatably supported by the supporting member 161. A
roller 165 and a shutter member 167 are attached to a distal end of
each long link 163a. One end of each spring member 169 is also
connected to a distal end of a short link 163b, and the other end
of each spring member 169 is fixed to a supporting member 161.
Consequently, the linking member 163 is urged by the urging force
of the spring member 169 in the direction in which the distal ends
of the pair of long links 163a approach each other.
[0065] The rollers 165 are attached so as to be able to rotate at
the distal ends of the long links 163a of the linking members 163.
The rollers 165 roll along the cam surface 171 of the shutter cam
170 during the period before and after lateral sealing. The cam
surface 171 includes a flat surface 171a that extends a first
distance in the conveyance direction of the tubular film Fm, and a
waved surface 171b that extends a second distance after the flat
surface 171a.
[0066] When the rollers 165 roll over the flat surface 171a, the
pair of shutter members 167 descend the first distance vertically
while holding the tubular film Fm therebetween. When the rollers
165 roll over the waved surface 171b, the pair of shutter members
167 descend the second distance while oscillating and holding the
tubular film Fm therebetween.
[0067] For convenience in the description, the zone in which the
rollers 165 roll over the flat surface 171a is referred to as the
first zone, and the zone in which the rollers 165 roll over the
waved surface 171b is referred to as the second zone. Lateral
sealing of the tubular film Fm is performed when the pair of
rollers 165 is in the first zone. When the pair of rollers 165 is
in the second zone, the tubular film Fm oscillates in a direction
which intersects with the conveyance direction and the lateral
direction.
[0068] The shutter members 167 are longer than the width of the
tubular film Fm, and both ends thereof are fixed at the distal ends
of the long links 163a of the linking members 163. The pair of
shutter members 167 hold the tubular film Fm therebetween earlier
than the sealing jaws 51, and prevent the products C from falling
above the sealed portion during lateral sealing of the tubular film
Fm. At least the portion of the shutter members 167 that holds the
tubular film Fm therebetween is a coil spring.
[0069] (2-3-6) Lateral Sealing Mechanism 17
[0070] FIG. 5 is a side view showing the lateral sealing mechanism.
FIG. 6 is a side view showing the trajectory of the sealing jaws.
As shown in FIG. 5, the lateral sealing mechanism 17 has a first
sealing mechanism 50a and a second sealing mechanism 50b. The
sealing mechanism positioned to the left of the tubular film Fm in
FIG. 5 is the first sealing mechanism 50a, and the sealing
mechanism positioned to the right of the tubular film Fm is the
second sealing mechanism 50b.
[0071] The first sealing mechanism 50a and second sealing mechanism
50b hold the tubular film Fm therebetween while causing the sealing
jaws 51, 52, respectively, to turn in a D shape (see, for example,
the trajectory of the sealing jaws indicated by dotted lines in
FIG. 6).
[0072] The sealing jaws 51, 52 have heaters in the inside thereof.
Sealing surfaces of the sealing jaws 51, 52 are heated by the
heaters, and a portion of the tubular film Fm held between the
sealing jaws 51, 52 is thereby sealed.
[0073] For convenience in this description, the sealing jaw 51 on
the side of the first sealing mechanism 50a is referred to as the
first sealing jaw 51a, and the sealing jaw 51 on the side of the
second sealing mechanism 50b is referred to as the second sealing
jaw 51b. The first sealing jaw 51a and the second sealing jaw 51b
hold the tubular film Fm therebetween and press against each other
to form a seal.
[0074] In the same manner, the sealing jaw 52 on the side of the
first sealing mechanism 50a is referred to as the first sealing jaw
52a, and the sealing jaw 52 on the side of the second sealing
mechanism 50b is referred to as the second sealing jaw 52b. The
first sealing jaw 52a and the second sealing jaw 52b hold the
tubular film Fm therebetween and press against each other to form a
seal.
[0075] The term "sealing jaws 51, 52" is used when referring to
components that are common to both sealing jaws.
[0076] The sealing jaws 51, 52 are rotated about axes C1, C2 by a
drive motor (not shown). Specifically, the first sealing jaws 51a,
52a are rotated about the axis C1, and the second sealing jaws 51b,
52b are rotated about the axis C2.
[0077] FIG. 7 is a plan view showing the area around the sealing
jaws. In FIG. 7, heaters 71 and a cutting mechanism 72 are built
into the sealing jaws 51. The heaters 71 are inserted two each into
the first sealing jaw 51a and the second sealing jaw 51b in the
longitudinal direction thereof. The heaters 71 receive electrical
power from electrical wiring 76a to generate heat, and heat the
first sealing jaw 51a and second sealing jaw 51b to a sealing
temperature that corresponds to the tubular film Fm.
[0078] The cutting mechanism 72 is provided to the first sealing
jaw 51a on the side of the first sealing mechanism 50a, and has a
cutter 72a and a cutter driving mechanism 72b. In accordance with
the sealing timing of the tubular film Fm, the cutter 72a is
advanced by the cutter driving mechanism 72b toward the second
sealing jaw 51b from inside a slide space formed in the first
sealing jaw 51a.
[0079] An air cylinder is employed in the cutter driving mechanism
72b to reciprocally move the cutter 72a in a predetermined
direction. Therefore, between the first sealing jaw 51a and the
second sealing jaw 51b, or between the first sealing jaw 52a and
the second sealing jaw 52b, the cutter 72a presses on the position
of the sealed portion substantially at the center in the width
direction thereof, and the sealed portion is cut. As a result, one
bag at a time is separated off and discharged to a chute conveyor
23 (refer to FIG. 1).
[0080] (2-3-7) Lateral Drive Mechanism 55
[0081] FIG. 8 is an external perspective view showing the lateral
drive mechanism of the sealing jaws. In FIG. 8, the first sealing
mechanism 50a is supported by a first horizontal movement plate
61a, and the second sealing mechanism 50b is supported by a second
horizontal movement plate 61b. The first horizontal movement plate
61a and the second horizontal movement plate 61b are moved
horizontally by the lateral drive mechanism 55 shown in FIG. 8.
[0082] As shown in FIG. 8, the lateral drive mechanism 55 has a
drive mechanism 65 for moving the first horizontal movement plate
61a and the second horizontal movement plate 61b toward or away
from each other.
[0083] The drive mechanism 65 has a ball screw 80a, a first nut 81,
a second nut 82, a first connecting rod 83, a second connecting rod
84, third connecting rods 85, and a fourth connecting rod 86.
[0084] The ball screw 80a is rotated by a servo motor 80 (refer to
FIG. 3). The first nut 81 and the second nut 82 are screwed onto
the ball screw 80a. The first connecting rod 83 and the second
connecting rod 84 are provided so as to be orthogonal to the ball
screw 80a in the horizontal direction. The pair of third connecting
rods 85 are provided in the direction of movement of the first
horizontal movement plate 61a and the second horizontal movement
plate 61b. The fourth connecting rod 86 is provided parallel to the
third connecting rods 85.
[0085] The first connecting rod 83 is connected to the third
connecting rods 85 via a joint 87, and distal ends of the third
connecting rods 85 are fixed to a lateral end surface of the second
horizontal movement plate 61b. The third connecting rods 85 are
passed through the first horizontal movement plate 61a so as to be
able to slide.
[0086] The second connecting rod 84 is connected to the fourth
connecting rod 86 via a joint 88, and a distal end of the fourth
connecting rod 86 is fixed to a lateral end surface of the first
horizontal movement plate 61a.
[0087] The portion of the ball screw 80a on which the first nut 81
is screwed and the portion of the ball screw 80a on which the
second nut 82 is screwed are threaded in opposite directions each
other.
[0088] Through the drive mechanism 65 described above, the first
horizontal movement plate 61a and the second horizontal movement
plate 61b can be moved toward or away from each other by rotation
of the ball screw 80a.
[0089] (3) Operation of the Packaging Machine 1
[0090] The sequence of operations of the packaging machine 1 will
next be described. Packaged articles (hereinafter referred to as
products C) weighed by the combination weighing device 2 are
sequentially dropped into the top open end of the tube 13b. At this
time, the outer periphery of the tube 13b is covered by the tubular
film Fm for packaging the products C.
[0091] The products C pass through the tube 13b, and are discharged
from the bottom open end of the tube 13b. Below the bottom open
end, the pair of brushes 191 hold the tubular film Fm therebetween
and temporarily block the passage of the products C.
[0092] FIG. 9 is a chart showing synchronized operation of the
periods of discharge of the products C, opening and closing of the
brushes, opening and closing of the shutter, and opening and
closing of the sealing jaws. Here, "closed" means that the tubular
film Fm is held closed so that products C are not allowed to pass
through, and "open" means that the closing off of the tubular film
Fm is released and products C are allowed to pass through.
[0093] In FIG. 9, the brushes 191 are closed from before the
products C are dropped, and the brushes 191 begin to open when the
controller receives a signal (discharge completion signal)
indicating that products C have been discharged from the
combination weighing device 2. Therefore, the period during which
advancement of the products C is stopped by the brushes 191 is
short. During this short period, the distance between the leading
end and the trailing end of the products C advancing as a vertical
stream is reduced, vibration created by rotation of the brushes 191
is transmitted to the packaged articles, and the gaps between
products C are filled. The brushes 191 move apart from each other
and send out the products C while vibrating the tubular film Fm by
the rotation and reciprocal movement.
[0094] In FIG. 9, since the shutter members 167 are closed from
before the brushes 191 begin to open, the products C are stopped
between the brushes 191 and the shutter members 167, and during
this time, the products C are vibrated by the rotation of the
brushes 191 so that the gaps between the products C are further
filled. The shutter members 167 descend the first distance
vertically in the closed state, and then descend the second
distance while oscillating. The oscillation of the shutter members
167 is transmitted to the products C, and the gaps between the
products C are further filled.
[0095] In FIG. 9, while the shutter members 167 are closed, the
first sealing jaw 51a and the second sealing jaw 51b hold and
laterally seal the tubular film Fm therebetween, the tubular film
Fm being positioned below the shutter members 167. Lateral sealing
is performed while the shutter members 167 descend the first
distance, the top part of a bag and the bottom part of the
succeeding bag are formed, the center of the sealed part is
simultaneously cut, and a bag packed with products C is
completed.
[0096] (4) Characteristic Features
[0097] (4-1)
[0098] In the packaging machine 1, since the pair of shutter
members 167 holds the tubular film Fm therebetween and shakes the
tubular film Fm, the packaged articles on the upstream side of the
shutter members 167 aggregate toward the side of the shutter
members 167 while the vibration of the shutter members 167 causes
the gaps between the packaged articles to be filled. Since the
packaged articles aggregate by inertia due to the vibration,
fragmentation thereof is less likely than in a case in which the
packaged articles are compressed by direct contact.
[0099] (4-2)
[0100] In the packaging machine 1, merely by the movement of the
rollers 165 on the waved surface 171b of the shutter cam 170, the
shutter members 167 are shaken in accordance with the waved surface
171b. This configuration is achieved by a simple mechanism, and the
ability to easily change the pattern of shaking by changing the
waves on the cam surface gives the design a high degree of freedom.
Since the portions that contact the shutter cam 170 are rollers
165, noise and abrasion are suppressed.
[0101] (4-3)
[0102] In the packaging machine 1, since the pair of shutter
members 167 descends while holding the tubular film Fm therebetween
and shaking, the inertial force at reversal of the shaking
direction acts in the direction in which the shutters open.
However, the shutter members 167 are coil springs and therefore
flex in response to the acting inertial force, and the shaking is
therefore kept from enlarging the gap between the shutter members
167.
[0103] (4-4)
[0104] In the packaging machine 1, the sealing jaws 51 seal the
tubular film Fm while the pair of shutter members 167 is advancing
the first distance. Specifically, since sealing is performed before
the shutter members 167 begin shaking, fragments of the packaged
articles are prevented from becoming trapped in the sealed portion
even when fragments drop from the gap between the shutter members
167 after the shutter members 167 begin shaking.
[0105] (5) Modifications
[0106] In the embodiment described above, the cam surface 171 of
the shutter cam 170 is not left-right symmetrical about the central
axis thereof in the longitudinal direction, but this configuration
is not limiting, and the cam surface 171 may be left-right
symmetrical.
[0107] FIG. 10 is a side view showing the shutter mechanism in the
first state in the packaging machine according to a modification.
In FIG. 10, the cam surface 171 is left-right symmetrical about the
central axis CO. Consequently, when the pair of rollers 165
descends at the same height position, the shutter members 167 are
opened by the peaks of the waved surface. Since the shutter members
167 are thereby unable to cause the tubular film Fm to oscillate,
the height position is varied so that when one of the pair of
rollers 165 is facing a peak, the other is facing a valley. As a
result, the shutter members 167 can oscillate while closing the
tubular film Fm.
INDUSTRIAL APPLICABILITY
[0108] Through the present invention, the amount of packaging
material used can be reduced while fragmentation of packaged
articles and trapping of fragments of packaged articles in the
sealed portion are suppressed. The present invention is therefore
useful in packaging machines in general.
* * * * *