U.S. patent application number 11/349841 was filed with the patent office on 2006-09-21 for opening method for packaging bag with fastener.
This patent application is currently assigned to TOYO JIDOKI CO., LTD. Invention is credited to Sumio Fukuda.
Application Number | 20060207225 11/349841 |
Document ID | / |
Family ID | 36169185 |
Filed Date | 2006-09-21 |
United States Patent
Application |
20060207225 |
Kind Code |
A1 |
Fukuda; Sumio |
September 21, 2006 |
Opening method for packaging bag with fastener
Abstract
An opening method for a packaging bag with a fastener enables
the fastener to be surely opened with a simplified arrangement and
by a simple operation as compared to the prior art. A packaging bag
with a fastener is held by being gripped at the laterally opposite
side edges thereof with a pair of grippers. A pair of suction cups
are disposed at respective stand-by positions at both sides of the
bag. The suction cups are moved to respective mutually close
positions and allowed to adhere to both side surfaces of the bag at
respective regions where the fastener is present. The suction cups
adhering to the bag are retracted to respective intermediate
positions. The movement of the suction cups between the mutually
close positions and the intermediate positions is repeated a
plurality of times. Thereafter, the suction cups are returned to
the stand-by positions. The fastener is opened stepwise.
Inventors: |
Fukuda; Sumio; (Iwakuni-shi,
JP) |
Correspondence
Address: |
THOMAS M. GALGANO, ESQ.;GALGANO & BURKE, LLP
SUITE 135
300 RABRO DRIVE
HAUPPAUGE
NY
11788
US
|
Assignee: |
TOYO JIDOKI CO., LTD
|
Family ID: |
36169185 |
Appl. No.: |
11/349841 |
Filed: |
February 8, 2006 |
Current U.S.
Class: |
53/492 ;
53/386.1 |
Current CPC
Class: |
B31B 50/80 20170801;
B65B 43/30 20130101 |
Class at
Publication: |
053/492 ;
053/386.1 |
International
Class: |
B65B 41/00 20060101
B65B041/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 17, 2005 |
JP |
2005-077056 |
Claims
1. A method of opening a packaging bag with a fastener that is
gripped at laterally opposite side edges thereof with a pair of
grippers by using a pair of suction-adhering members disposed at
both sides of said packaging bag in such a manner that said
suction-adhering members are moved toward each other so as to
adhere to both side surfaces of said packaging bag at respective
regions where said fastener is present, and said suction-adhering
members adhering to said packaging bag are moved away from each
other to open said packaging bag, said method comprising: repeating
a plurality of times a reciprocating operation including a series
of operations of moving said suction-adhering members toward each
other, making said suction-adhering members adhere to said
packaging bag, and moving said suction-adhering members adhering to
said packaging bag away from each other.
2. The method of claim 1, wherein before starting said
reciprocating operation, said suction-adhering members are placed
at respective stand-by positions apart from each other by a
predetermined distance, and when moved away from each other during
said reciprocating operation, said suction-adhering members are
moved to respective intermediate positions where they are closer to
each other than at said stand-by positions, except for a final
cycle of said reciprocating operation, which is repeated said
plurality of times.
3. The method of claim 1, wherein said reciprocating operation is
repeated at least three times.
4. The method of claim 2, wherein said reciprocating operation is
repeated at least three times.
5. The method of claim 1, wherein said pair of suction-adhering
members are positioned so that respective centers of
suction-adhering surfaces of said suction-adhering members are
displaced relative to each other in a longitudinal direction of
said fastener.
6. The method of claim 5, wherein said suction-adhering members are
capable of returnably tilting within a plane perpendicular to the
side surfaces of said packaging bag and containing said
fastener.
7. The method of claim 6, wherein said suction-adhering members are
urged toward respective predetermined positions with predetermined
postures by respective resilient members, and when said
suction-adhering members have performed said tilting, they are
returned by said resilient members.
8. The method of claim 1, wherein said suction-adhering members are
disposed so that their respective suction-adhering surfaces face
obliquely upward.
9. The method of claim 5, wherein said suction-adhering members are
disposed so that their respective suction-adhering surfaces face
obliquely upward.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an opening method for
opening a fastener of a packaging bag (hereinafter, a packaging bag
with a fastener will be occasionally referred to as a "zippered
packaging bag"). More particularly, the present invention relates
to a packaging bag opening method suitable for use in an apparatus
that performs automatic packaging of food or the like while moving
a packaging bag by gripping the laterally opposite side edges
thereof with a pair of grippers, wherein a zippered bag is used as
the packaging bag.
[0003] 2. Discussion of Related Art
[0004] There has been used a zippered bag whose mouth is closable
by fitting engagement between a rib and an associated groove that
constitute a fastener. More specifically, the rib is formed to
extend in the width direction on one of the inner surfaces of the
opposite walls of the bag near the upper edge thereof. The groove
is formed to extend widthwise on the other of the inner surfaces of
the bag walls. The zippered bag is usable in automatic packaging of
food or the like. When the zippered bag is used, it has to be
opened before filling of food. A variety of apparatus and methods
for opening the zippered bag have been proposed.
[0005] Japanese Patent No. 3429872 discloses an opening apparatus
for a packaging bag with a fastener. In this apparatus, first,
suction cups are operated to act on both side surfaces of the bag
at respective positions above the fastener to open the part of the
bag above the fastener. Then, the upper edges of the opposite walls
of the opened part of the bag are gripped with grippers,
respectively, and the grippers are rotated in opposite directions
to each other about their own axes, thereby partially opening the
fastener. Thereafter, the grippers are moved away from each other
to fully open the fastener, thereby opening the bag. In this case,
the apparatus requires, in addition to suction cups, grippers that
are capable of opening and closing, and mechanisms for rotating the
grippers or moving them toward or away from each other. Thus, the
apparatus has a complicated structure and suffers increased costs.
In addition, it takes a great deal of time to carry out maintenance
or cleaning works. Because the upper edges of the bag are gripped
and pulled with the grippers, the bag mouth may be damaged, causing
the appearance of the bag to be degraded.
[0006] Japanese Patent Application Unexamined Publication (KOKAI)
No. Hei 8-104308 discloses a fastener opening apparatus for a
packaging bag with a fastener. The apparatus includes a set of
driving and driven rollers disposed at both sides of a bag to be
opened. The driving and driven rollers have their axes extending
perpendicular to the extending direction of the bag fastener. The
rotation of the driven roller is forcedly checked at a certain
position against the rotation of the driving roller, thereby
causing the opposite walls of the bag to slide relative to each
other at the fastener part of the bag, and thus partially
disengaging the male and female fastener elements from each other.
This apparatus, however, only provides an automated fastener
opening operation, which has heretofore been carried out by a
manual operation, and is capable of opening the fastener only
partially. To fully open the bag, a device for this purpose is
needed separately. Therefore, the apparatus is difficult to apply
to an automatic packaging machine. The arrangement of the apparatus
will become extremely complicated if it is adapted to be applicable
to an automatic packaging machine. In addition, because the
fastener part of the bag is pressed from both sides to cause the
opposite bag walls to slide relative to each other, the bag mouth
is likely to be deformed, i.e. wrinkled or elongated, or
damaged.
[0007] Japanese Patent Application Unexamined Publication (KOKAI)
No. Hei 10-81313 discloses an opening apparatus for a bag with a
fastener. With the apparatus, suction cups adhering to the opposite
side walls of a bag to be opened are rotated about their own axes
at respective present positions to open a part of the bag above the
fastener. Then, the suction cups are retracted to pull the side
walls of the bag. Meanwhile, a nozzle is lowered into the open part
of the bag while injecting pneumatic pressure thereinto. Thus, the
push-down force of the nozzle and the compressed air pressure are
applied to open the fastener. The operation of the suction cups
takes place in two steps. In addition, the apparatus uses the
nozzle device. Therefore, the arrangement is complicated. Further,
the bag may be deformed or damaged by forcing of the nozzle into
the bag.
[0008] Japanese Patent No. 3578924 discloses a method and apparatus
for opening a fastener at the mouth of a bag. The apparatus is
arranged as follows. After suction cups have been made to adhere to
the opposite side walls of a bag, a frame rotatably supporting one
of the suction cups is lowered to move the suction cup downward
while tilting it, thereby turning over one side wall at the mouth
of the bag to disengage the fastener. Thus, the arrangement is
complicated.
[0009] Japanese Patent Application Unexamined Publication (KOKAI)
No. 2004-17985 discloses an opening apparatus for a bag with a
fastener. The apparatus uses a pair of vacuum cups having different
configurations from each other. One of the vacuum cups is provided
with a trumpet-shaped recess. The other vacuum cup is provided with
a rib so that the cup has a flat suction-adhering surface. The cups
each have a flat suction-adhering surface. A bag to be opened is
held in such a manner that the male profile side of the fastener
faces the cup having the recess, whereby the male profile side of
the fastener is partially distorted during suction, thereby
disengaging a part of the fastener. In this arrangement, suction
cups used in a pair are different in configuration from each other.
Accordingly, the apparatus cannot function as desired if the bag is
held in reverse orientation to that in which the bag is supposed to
be held, in terms of the front and back faces.
[0010] The above-described conventional apparatus are all
complicated in arrangement, which causes problems in terms of
maintenance and cleaning, or problems in application to an
automatic packaging machine. The difference in structure between a
pair of suction cups used in the conventional apparatus presents a
problem that the bag opening operation cannot be performed
independently of the orientation of the bag to be opened. The
above-described prior art is arranged to open the fastener in one
step of opening operation. Particularly, the apparatus disclosed in
the last four of the above-described patent documents use
frictional force between the rollers and the bag walls, the
adhering force of the suction cups, or pneumatic pressure from the
nozzle to open the fastener. Therefore, the force for opening the
fastener cannot be said to be sufficiently strong. If the engaging
force between the male and female fastener elements is strong, the
apparatus may fail to open the fastener.
SUMMARY OF THE INVENTION
[0011] The present invention was made in view of the
above-described problems associated with the prior art.
[0012] Accordingly, an object of the present invention is to
provide an opening method for a packaging bag with a fastener that
can open the bag more easily and surely than by the prior art
method with a simplified arrangement. That is, the present
invention is based on the knowledge the present inventor obtained
in the process of carrying out research and development that a
packaging bag with a fastener can be opened more easily and surely
by repeating a simple opening operation a plurality of times to
thereby carry out the opening process stepwise than by opening the
bag in one step of opening operation.
[0013] To attain the above-described object, the present invention
provides a method of opening a packaging bag with a fastener that
is gripped at laterally opposite side edges thereof with a pair of
grippers by using a pair of suction-adhering members disposed at
both sides of the packaging bag. The suction-adhering members are
moved to perform a reciprocating operation a plurality of times.
The reciprocating operation includes a series of operations of
moving the suction-adhering members toward each other, making the
suction-adhering members adhere to both side surfaces of the
packaging bag at respective regions where the fastener is present,
and moving the suction-adhering members adhering to the packaging
bag away from each other. With this method, the process of opening
the fastener proceeds gradually, and the fastener can be easily and
surely opened.
[0014] In one embodiment, before starting the reciprocating
operation, the suction-adhering members are placed at respective
stand-by positions apart from each other by a predetermined
distance. When moved away from each other during the reciprocating
operation, the suction-adhering members are moved to respective
intermediate positions where they are closer to each other than at
the stand-by positions, except for the final cycle of the
reciprocating operation, which is repeated a plurality of times.
This arrangement makes it possible to shorten the stroke of the
reciprocating operation and to improve throughput capability.
[0015] In another embodiment, the reciprocating operation is
repeated at least three times. By repeating the reciprocating
operation at least three times, presently used general zippered
packaging bags can be surely opened, and the bag opening operation
is stabilized.
[0016] In still another embodiment, the pair of suction-adhering
members are positioned so that the respective centers of
suction-adhering surfaces of the suction-adhering members are
displaced relative to each other in the longitudinal direction of
the fastener. If the suction-adhering surfaces adhere to both side
surfaces of the bag in a state where the fastener is closed and the
opposite side walls of the bag adhere to each other in such a way
that the suction-adhering surfaces are superimposed over one
another, a negative pressure is created in the bag. The negative
pressure acts to reduce the suction-holding force when the
suction-adhering members move away from each other. By adopting the
above-described arrangement, however, the reduction of the
suction-holding force can be minimized.
[0017] In a further embodiment, the suction-adhering members are
capable of returnably tilting within a plane perpendicular to the
side surfaces of the packaging bag and containing the fastener.
When performing the tilting operation, the suction-adhering members
apply a massage-like action to the portions of the bag to which
they are adhering so as to loosen the fastener, thereby promoting
disengagement of the male and female fastener elements.
[0018] In a still further embodiment, the suction-adhering members
are urged toward respective predetermined positions with
predetermined postures by respective resilient members, and when
the suction-adhering members have performed the tilting operation,
they are returned by the resilient members. With this arrangement,
the positions and postures of the suction-adhering members when
adhering to the bag are kept constant and stabilized, and the bag
opening operation becomes stabilized.
[0019] In a still further embodiment, the suction-adhering members
are disposed so that their respective suction-adhering surfaces
face obliquely upward. With this arrangement, when the
suction-adhering members adhere to the bag, the mouth at the upper
edge of the bag is always opened. Accordingly, once the fastener
has been opened, even partially, air can immediately flow into the
bag, whereby the following fastener opening and bag opening
operations are facilitated.
[0020] According to the present invention, a packaging bag with a
fastener can be opened simply by moving a pair of suction-adhering
members to perform the above-described reciprocating operation.
Therefore, an apparatus for carrying out the opening method is
extremely simplified in arrangement. The opening operation can be
accomplished simply by repeating the reciprocating operation of the
suction-adhering members a plurality of times. Accordingly, the
opening operation can be performed extremely easily, simply and
surely. Further, the process of opening the bag is carried out
stepwise by repeating the reciprocating operation a plurality of
times, unlike the conventional practice of opening the bag in only
one step of opening operation. Therefore, the bag can be surely
opened. Once a part of the fastener has been opened, the rest of it
can be opened very easily. Because the arrangement of the apparatus
is simplified, the apparatus is excellent in maintainability,
cleanability, and so forth.
[0021] Other objects and advantages of the present invention will
become apparent from the following detailed description of
illustrated embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a perspective view showing the conceptual
arrangement of an automatic packaging machine for carrying out a
bag opening method according to a first embodiment of the present
invention.
[0023] FIGS. 2a and 2b are partially-sectioned plan and side views,
respectively, showing suction cups at their respective stand-by
positions.
[0024] FIGS. 3a and 3b are partially-sectioned plan and side views,
respectively, showing the suction cups that have advanced to their
respective positions where they adhere to a bag to be opened.
[0025] FIGS. 4a and 4b are partially-sectioned plan and side views,
respectively, showing the suction cups that have advanced to their
respective final, mutually close positions.
[0026] FIGS. 5a and 5b are partially-sectioned plan and side views,
respectively, showing the suction cups that have returned to their
respective intermediate positions.
[0027] FIGS. 6a and 6b are partially-sectioned plan and side views,
respectively, showing the suction cups that have advanced to their
mutually close positions again.
[0028] FIGS. 7a and 7b are partially-sectioned plan and side views,
respectively, showing the suction cups that have returned to their
respective intermediate positions again.
[0029] FIGS. 8a and 8b are partially-sectioned plan and side views,
respectively, showing the suction cups that have returned to their
respective stand-by positions after completion of opening the
bag.
[0030] FIGS. 9a and 9b are diagrams showing an essential part of an
apparatus for carrying out a second embodiment of the present
invention, in which FIG. 9a shows suction cups at their respective
stand-by positions, and FIG. 9b shows the suction cups at their
mutually close positions.
[0031] FIG. 10 is a diagram showing a part of a bag opening process
according to a third embodiment of the present invention.
[0032] FIG. 11 is a diagram showing another part of the bag opening
process according to the third embodiment of the present
invention.
[0033] FIG. 12 is a diagram showing another part of the bag opening
process according to the third embodiment of the present
invention.
[0034] FIG. 13 is a diagram showing another part of the bag opening
process according to the third embodiment of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0035] Embodiments of the present invention will be described below
with reference to the accompanying drawings. It should be noted,
however, that the following embodiments are for illustrative
purposes only, and that the scope of the present invention is not
limited to these embodiments.
[0036] FIG. 1 is a perspective view conceptually showing an
automatic packaging machine for food that employs an opening method
for a packaging bag with a fastener according to one embodiment of
the present invention. In the figure, a turntable 2 is secured to a
rotating shaft 3 driven by a driving device (not shown) so that the
turntable 2 is rotatable together with the rotating shaft 3 as one
unit. In this embodiment, the turntable 2 rotates intermittently in
the direction indicated by the arrow in the figure. A pair of
grippers 5 are disposed underneath the turntable 2 near the outer
periphery thereof with a predetermined spacing in the
circumferential direction to grip the laterally opposite side edges
of a bag 4. The grippers 5 receive the bag 4 supplied from the
outside of the turntable 2 and move it in a vertically held
position to various steps successively to perform operations such
as opening the bag, filling the bag with contents, sealing the bag
mouth, and discharging the finished product. For these operations
or arrangements therefor, publicly known techniques can be used
satisfactorily, except a bag opening apparatus (described later).
Therefore, a detailed description thereof is omitted. The
arrangement for securing the grippers 5 to the turntable 2 and the
operation thereof are also publicly known; therefore, a detailed
description thereof is omitted.
[0037] Suction cups 6 and 7 serving as suction-adhering members are
secured to respective arms 8 and 9 and disposed facing each other
across the bag 4. The way in which the suction cups 6 and 7 are
secured to the arms 8 and 9 and the operation of the suction cups 6
and 7 will be detailed later. A driving mechanism 11 for operating
the arms 8 and 9 will be explained first. It should be noted the
driving mechanism 11 is not necessarily limited to the one that is
arranged as stated below, but any driving mechanism capable of
driving the suction cups 6 and 7 to perform an operation that will
be described later.
[0038] A cam 12 is secured to a cam shaft 13 driven to rotate by a
driving device (not shown) so that the cam 12 rotates together with
the cam shaft 13 as one unit. A cam lever 14 is secured to a lever
shaft 16 rotatably supported appropriately so that the cam lever 14
pivots together with the lever shaft 16 as one unit. The cam lever
14 rotatably supports a cam roller 15 at a longitudinally
intermediate position thereon. One end of a return spring 17, which
is a tension coil spring, is attached to the distal end of the cam
lever 14. The other end of the spring 17 is attached to a spring
hook 18 secured to a frame (not shown). Accordingly, the cam lever
14 is constantly urged in a direction in which the cam roller 15
contacts the outer peripheral surface of the cam 12. The outer
profile of the cam 12 has the following portions (not denoted by
reference numerals in the figure): a small diameter portion formed
over a certain angular range with a small diameter from the axis of
the shaft 13; a first displacement portion having a diameter
gradually increasing from one end of the small diameter portion; a
large diameter portion maintaining the length of the diameter at
the terminating end of the first displacement portion over a
certain angular range; and a second displacement portion having a
diameter gradually decreasing from the large diameter portion to
the other end of the small diameter portion.
[0039] A hollow stand 19 is stood on the top of a machine base (not
shown). The stand 19 rotatably supports a driving shaft 20. A
connecting lever 21 is secured at one end thereof to the lower end
of the driving shaft 20 so that the lever 21 is rotatable together
with the driving shaft 20 as one unit. One end of an air cylinder
22 is pivotably attached to the other end of the lever 21. The
other end of the air cylinder 22 is pivotably attached to the cam
lever 14 at a longitudinally intermediate position between the cam
roller 15 and the end thereof to which the spring 17 is attached.
The air cylinder 22 is connected to a compressed air source (not
shown). Compressed air is supplied into and discharged from the air
cylinder 22 under appropriate control, causing a rod 22a to extend
and contract in response to the supply and discharge of compressed
air, thereby moving the suction cups 6 and 7 between their
respective mutually close positions and intermediate positions as
explained hereinafer.
[0040] A plate-shaped gear holder 23 is secured to the upper end of
the stand 19 as shown in the figure. A pinion 24 is positioned in a
recess (no reference numeral) formed in an approximately central
portion of the gear holder 23 and fixed to the upper end of the
driving shaft 20. Racks 25 and 26 are disposed and guided in
respective slots (no reference numeral) formed on the gear holder
23. The racks 25 and 26 extend parallel to each other across the
pinion 24. As the pinion 24 rotates, the racks 25 and 26 move
opposite to each other in their longitudinal directions. The
above-described arms 8 and 9 are integrally secured to the
respective distal ends of the racks 25 and 26. The arms 8 and 9
both have an L-shape as shown in the figure. The arm 8 associated
with the suction cup 6 is longer than the other arm 9, so that the
suction cups 6 and 7 are positioned facing each other across the
bag 4 as illustrated in the figure. Piping tubes 27 and 28 are
connected to the suction cups 6 and 7, respectively. The tubes 27
and 28 are each connected to a vacuum pump (not shown) through
appropriate members, such as a switching valve and a filter (not
shown). A nozzle 29 is disposed so that an opening end 29a thereof
is positioned slightly above the upper edge of the bag 4. The
nozzle 29 injects air to assist in the operation of opening the bag
4 that is performed by the action of the suction cups 6 and 7.
[0041] The bag 4 is opened as follows. When the cam roller 15 is on
the small diameter portion of the rotating cam 12, the suction cups
6 and 7 are at rest at their respective stand-by positions apart
from each other. When the bag 4 held by the grippers 5 has moved to
and stopped at a bag opening position, the cam roller 15 moves
along the first displacement portion toward the large diameter
portion in response to the rotation of the cam shaft 13. The cam
lever 14 moves in the direction of the arrow in the figure, causing
the suction cups 6 and 7 to move to their mutually close positions
at which the suction cups 6 and 7 abut against each other across
the bag 4. A vacuum is applied to the suction cups 6 and 7 so that
the suction cups 6 and 7 adhere to the outer surfaces of the
opposite side walls of the bag 4. While the cam roller 15 is moving
along the large diameter portion of the cam 12, the cam lever 14
remains at the present position. Meanwhile, the air cylinder 22
operates so that the suction cups 6 and 7 are returned from the
mutually close positions to respective intermediate positions
between the mutually close positions and the stand-by positions and
moved to the mutually close positions again and then returned to
the intermediate positions again. The reciprocating operation of
the suction cups 6 and 7 between the mutually close positions and
the intermediate positions is repeated a plurality of times. When
the suction cups 6 and 7 are finally returned to the mutually close
positions, the cam roller 15 is located at the end of the large
diameter portion opposite to the leading end thereof. Then, the cam
roller 15 moves along the second displacement portion toward the
small diameter portion. Consequently, the cam lever 14 pivots in a
direction opposite to the arrow direction shown in the figure to
return to the previous position. Thus, the suction cups 6 and 7 are
also returned to the stand-by positions. While the cam roller 15 is
moving along the small diameter portion of the cam 12, the bag 4
moves to the subsequent step. The operations of the arms 8 and 9
and the suction cups 6 and 7 in this embodiment will be explained
below in detail with reference to FIGS. 2a and 2b and the following
figures.
[0042] FIGS. 2a and 2b are partially-sectioned plan and side views,
respectively, showing the bag 4 having moved to and stopped at the
bag opening position and the suction cups 6 and 7, together with
the arms 8 and 9, at the stand-by positions. The bag 4 is a
packaging bag with a fastener as stated above. As shown in FIG. 2b,
a fastener 4a is formed on the inner surfaces of the opposite side
walls of the bag 4 at a position slightly away from the upper edge
of the bag 4 to extend in the width direction of the bag 4. The
fastener 4a consists essentially of a male fastener element 4b
formed on the inner surface of one side wall of the bag 4 and a
female fastener element 4c formed on the inner surface of the other
side wall of the bag 4. The arrangement of the fastener 4a is
publicly known. Therefore, a detailed description thereof is
omitted. Regarding the arms 8 and 9, only the bent distal end
portions 8a and 9a thereof are shown in the figures.
[0043] The suction cup 6 has a suction cup body portion 6a having a
suction-adhering surface that is adapted to adhere to the bag 4 by
suction, for which a publicly known arrangement can be employed.
The suction cup 6 further has a shaft portion 6b extending rearward
from the rear end of the body portion 6a, and a flange 6c provided
at the rear end of the shaft portion 6b to extend radially outward
of the shaft portion 6b. The shaft portion 6b is fitted in a slot
8b formed in the bent portion 8a of the arm 8. The slot 8b has a
predetermined length in the width direction of the bag 4. The
suction cup 6 is urged forward, i.e. toward where the bag 4 is
positioned, by a compression spring 10 disposed around the shaft
portion 6b between the body portion 6a and the bent portion 8a. The
suction cup 6 is positioned with the flange 6c abutting on the bent
portion 8a. In this embodiment, the suction cup 6 has the shaft
portion 6b abutting on the upper end of the slot 8b as viewed in
FIG. 2a owing to the way in which the spring 10 is installed. It
should be noted, however, that the illustrated arrangement of the
suction cup 6 is not essential. The arrangement of the other
suction cup 7 and the way in which it is attached to the bent
portion 9a are the same as in the case of the suction cup 6.
Portions of the suction cup 7 corresponding to those of the suction
cup 6 are denoted by adding the same letters of English alphabet as
used for the corresponding portions of the suction cup 6 to
reference numeral 7. It should be noted, however, that the shaft
portion 7b abuts on the lower end of the slot 9b as viewed in FIG.
2a.
[0044] As shown in FIGS. 2a and 2b, the suction cups 6 and 7 stand
by at respective positions at both sides of the bag 4 a
predetermined distance away from each side of the bag 4 such that
the respective centers of the suction-adhering surfaces 6d and 7d
face approximately the center of the bag 4 in the width direction
thereof at substantially the same position as the fastener 4a of
the bag 4 in the height direction thereof. As will be clear from
FIG. 2a, however, the suction cups 6 and 7 are positioned so that
the respective axes are slightly displaced relative to each other
in the width direction of the bag 4. Further, as will be understood
from FIG. 2b, the suction cups 6 and 7 are disposed so that the
respective axes slightly tilt at the same angle to a horizontal
plane and the suction-adhering surfaces 6d and 7d face slightly
obliquely upward.
[0045] Next, as the cam 12 rotates, the cam roller 15 moves along
the first displacement portion, causing the suction cups 6 and 7 to
move toward each other as far as respective positions where the
suction cups 6 and 7 contact the opposite sides of the bag 4, as
shown in FIGS. 3a and 3b, as has been stated above. In this
embodiment, a vacuum is applied to the suction cups 6 and 7
slightly before the suction cups 6 and 7 reach the above-described
positions. The vacuum is kept applied to the suction cups 6 and 7
until completion of a series of opening operations (described
later). When the suction cups 6 and 7 are moved to the
above-described positions, because the suction-adhering surfaces 6d
and 7d of the suction cups 6 and 7 face obliquely upward as stated
above, the lower portions of the suction cups 6 and 7 abut against
each other across the bag 4, but the upper portions of the suction
cups 6 and 7 are separate from each other. In this case, however,
because the vacuum is acting on the suction cups 6 and 7, side wall
portions of the bag 4 above the fastener 4a, at least near where
the suction cups 6 and 7 are positioned, are opened by being sucked
to the suction cups 6 and 7, as shown in FIG. 3b. The inner
surfaces of side wall portions of the bag 4 below the fastener 4a
also slightly separate from each other, as shown in the figure,
owing to the presence of the fastener 4a in an area where the
suction-adhering surfaces 6d and 7d of the suction cups 6 and 7
overlap each other. It should be noted that in this embodiment the
cam roller 15 has not yet reached the large diameter portion of the
cam 12 even when the suction cups 6 and 7 have reach the
above-described positions.
[0046] As the cam 12 rotates further, the cam roller 15 reaches the
large diameter portion. Thereupon, the suction cups 6 and 7 assume
respective positions as shown in FIGS. 4a and 4b. That is, when in
the positions shown in FIGS. 3a and 3b, the suction cups 6 and 7
have already abutted against each other across the bag 4 at their
lower portions and cannot further advance as a whole. The arms 8
and 9, however, further advance against the forces of the springs
10 from the positions shown in FIGS. 3a and 3b to the respective
positions in FIGS. 4a and 4b, thus separating from the flanges 6c
and 7c, respectively. Meanwhile, the suction cups 6 and 7 have
their axes displaced relative to each other as stated above, and
the shaft portions 6b and 7b are respectively fitted in the slots
8b and 9b of the arms 8 and 9. Therefore, the shaft portions 6b and
7b move within the slots 8b and 9b to abut on the respective ends
thereof opposite to the above as shown in FIG. 4a, causing the
suction cups 6 and 7 to tilt slightly (the tilting action may be
regarded as tilting of the suction cups 6 and 7 within a plane
perpendicular to the side surfaces of the bag 4 and containing the
fastener 4a). Thus, the suction cups 6 and 7 pinching the fastener
4a of the bag 4 from both sides shift from the respective positions
shown in FIGS. 3a and 3b to the positions shown in FIGS. 4a and 4b,
thereby providing a massage-like action to loosen the fastener 4a
at the pinched portion. As a result, the fastener 4a is slightly
elastically deformed. That is, the mouth of the female fastener
element 4c widens a little, making it easy for the male fastener
element 4b to disengage from the female fastener element 4c.
[0047] The large diameter portion of the cam 12 is formed to extend
over a certain angular range, as has been stated above. While the
cam roller 15 is moving along the large diameter portion, the
following operation takes place: When the state shown in FIGS. 4a
and 4b is reached, the above-described air cylinder 22 is activated
at a predetermined timing to withdraw the rod 22a into the air
cylinder 22 by a predetermined length. In response to the
contraction of the rod 22a, the pinion 24 rotates through a
predetermined angle in a direction opposite to the above, causing
the suction cups 6 and 7 to retract to respective. intermediate
positions as shown in FIGS. 5a and 5b. During the retracting
movement to the positions shown in FIGS. 5a and 5b, the suction
cups 6 and 7 are adhering to the opposite side walls of the bag 4.
Thus, the suction cups 6 and 7 pull the bag 4 from both sides
thereof and hence act to open the fastener 4a at the portion
thereof where the suction cups 6 and 7 are adhering. Even if the
fastener 4a is not fully opened at that portion by the
above-described action, the male fastener element 4b begins to
disengage from the female fastener element 4c, as shown in FIGS. 5a
and 5b. It should be noted that if the suction cups 6 and 7 were
disposed in such a way that their respective axes coincide with
each other unlike in this embodiment, the following problem might
arise: While the suction cups 6 and 7 are adhering to the bag 4, a
negative pressure is created in the bag 4 at the suction-held
portion below the fastener 4a. Consequently, when the bag 4 is
pulled from both sides thereof, the pulling force is canceled by
the negative pressure, so that the suction holding of the bag 4 by
the suction cups 6 and 7 becomes incomplete. In such a case, the
suction cups 6 and 7 cannot pull the bag 4 sufficiently and may
separate from the bag 4 undesirably. With this embodiment, however,
a sufficiently strong suction-holding force can be maintained.
[0048] Next, the air cylinder 22 is activated in reverse to the
above to extend the rod 22a, causing the suction cups 6 and 7 to
assume respective positions as shown in FIGS. 6a and 6b. More
specifically, the suction cups 6 and 7 move toward the bag 4 again
to adhere to the bag 4 and perform the massaging operation to
loosen the fastener 4a, as has been stated above in connection with
FIGS. 4a and 4b, to reach the respective positions shown in FIGS.
6a and 6b. Then, the rod 22a of the air cylinder 22 contracts
again, causing the suction cups 6 and 7 to retract to the
intermediate positions again. The air cylinder 22 repeats the
contacting-extending operation a predetermined number of times
while the cam roller 15 is moving along the large diameter portion
of the cam 12. During this operation, a part of the fastener 4a is
fully opened, and the extent of the opening of the fastener 4a
gradually extends as shown in FIG. 7a. Once a part of the fastener
4a has been opened, it is easy to open the rest of it. Finally,
with the air cylinder 22 kept extended, the cam roller 15 moves
along the second displacement portion of the cam 12, causing the
suction cups 6 and 7 to return to the respective previous stand-by
positions. Thus, the fastener 4a of the bag 4 is opened over the
entire length thereof, and the bag 4 is fully opened as shown in
FIGS. 8a and 8b.
[0049] It should be noted that air is injected from the nozzle 29
during the above-described opening operation. As has been stated
above, the suction-adhering surfaces 6d and 7d of the suction cups
6 and 7 face obliquely upward so as to act to open the upper edge
portion of the bag 4 at all times. Therefore, once the fastener 4a
has been opened, even partially, flowing of air injected from the
nozzle 29 into the bag 4 is promoted to facilitate and ensure the
opening operation. Eventually, the bag 4 can be fully opened as far
as the bottom thereof. It should be noted that, during the
above-described operation, the grippers 5 gripping the laterally
opposite side edges of the bag 4 move toward each other by a
predetermined distance at a predetermined timing so as not to
interfere with the operation of opening the bag 4. The use of the
air cylinder 22 makes it possible to adopt an arrangement in which
the suction cups 6 and 7 are not retracted beyond the respective
intermediate positions except the final retracting operation.
Consequently, it is possible to shorten the reciprocating stroke of
the suction cups 6 and 7 and to eliminate useless movement of the
suction cups 6 and 7 and hence possible to improve throughput
capability.
[0050] FIGS. 9a and 9b are diagrams showing a second embodiment of
the present invention. FIG. 9a is a plan view corresponding to FIG.
2a. FIG. 9b is a plan view corresponding to FIG. 4a. In this
embodiment, suction cups 41 and 42 are secured to respective
holders 47 and 48 that are pivotably supported to arms 43 and 44
(only partially shown) by shafts 45 and 46, respectively. The
holders 47 and 48 are subjected to forces from tension springs 49
and 50 retained each at one end thereof by spring retainers 51 and
52, and positioned by abutting on respective stoppers 53 and 54.
The operations of the arms 43 and 44 and the suction cups 41 and 42
are substantially the same as in the first embodiment. It should be
noted, however, that the operation of tilting the suction cups 41
and 42 as shown in FIG. 9b is effected by pivoting of the holders
47 and 48 about the respective shafts 45 and 46 against the forces
of the springs 49 and 50. The other operations in this embodiment
will be understood from the description of the first embodiment.
Therefore, a description thereof is omitted. It should be noted
that in this embodiment the suction cups 41 and 42 are placed in
predetermined positions when retracted. Therefore, the suction cups
41 and 42 can surely adhere to the same positions on bags, and the
opening operation can be performed stably.
[0051] Although in the above-described first and second embodiments
the arms and the suction cups move further from the respective
positions shown in FIGS. 3a and 3b to those shown in FIGS. 4a and
4b, it should be noted that the arms and the suction cups may move
from the positions shown in FIGS. 3a and 3b directly to the
intermediate positions, not moving to the positions shown in FIGS.
4a and 4b, and finally retract to the stand-by positions. That is,
the interlocking force of the fastener depends on the arrangement
thereof. In a case where the interlocking force of the fastener is
relatively small so that the fastener can be opened without
performing the above-described massaging operation, it is
unnecessary to carry out the massaging operation. In the first and
second embodiments, the fastener opening operation is performed
twice in total. That is, the operation of returning the suction
cups to the respective intermediate positions while pulling the bag
from both sides thereof is performed once. In the second suction
cup returning operation, the suction cups are returned to the
respective stand-by positions. The present applicant confirmed that
ordinary zippered packaging bags presently used in automatic
packaging can be surely opened by performing the above-described
opening operation at least three times. The number of times of
repeating the opening operation, however, is not necessarily
limited to the above but may be determined according to the
specifications of bags to be used. Whether or not to perform the
massaging operation may also be determined according to need. In
the first and second embodiments, the operation of moving the
suction cups between the mutually close positions and the
intermediate positions is performed by using an air cylinder. It
is, however, also possible to effect the operation by using the cam
itself, for example. If the cam alone is used to perform all the
operations of moving the suction cups between the stand-by
positions and the mutually close positions and moving them between
the mutually close positions and the intermediate positions,
however, the cam has to be changed when the number of times of
repeating the opening operation is changed. In the case of the
foregoing embodiments, however, the number of times of repeating
the opening operation can be readily changed simply by controlling
the air cylinder.
[0052] In the foregoing first and second embodiments, the table of
the automatic packaging machine intermittently rotates, and the
above-described opening operation is performed while the bag is at
rest at the first step of the automatic packaging process. Japanese
Patent Application Unexamined Publication (KOKAI) No. 2002-255119,
for example, discloses a bag mouth opening apparatus for a bag with
no fastener that is conveyed continuously. It is useful for
realizing a high-speed automatic packaging machine that various
operations are performed on a bag being moved continuously as
disclosed in the JP(A) publication. The present invention is also
applicable in a case where a bag with a fastener is moved not
intermittently but continuously as in the above-described JP(A)
publication. More specifically, in Japanese Patent Application
Unexamined Publication (KOKAI) No. 2002-255119, one apparatus for
opening the bag mouth is provided along the bag conveying path.
When the present invention is applied to an automatic packaging
process in which a bag with a fastener is moved continuously,
however, a plurality, for example, two, of bag mouth opening
apparatuses are disposed along the bag conveying path. With the
plurality of apparatuses, the opening operation is repeated a
plurality of times, whereby a packaging bag with a fastener can be
surely opened. The opening operation will be explained below
briefly with reference to FIGS. 10 to 13.
[0053] An opening apparatus 71 used in this example may be the same
as disclosed in Japanese Patent Application Unexamined Publication
(KOKAI) No. 2002-255119. A pair of suction cups 74 and 75 are
disposed facing each other across a bag 72 held with grippers 73
and moved continuously. The suction cups 74 and 75 are positioned
in symmetry with respect to the travel line (shown by arrows in the
figure) of the bag 72. The suction cups 74 and 75 rotate in
opposite directions to each other about their respective axes 76
and 77 extending perpendicular to the plane of the figure. During
the rotation of the suction cups 74 and 75, the suction-adhering
surfaces thereof constantly face the bag 72. During the movement of
the suction cups 74 and 75, their positions are kept symmetric with
respect to the travel line of the bag 72 at all times. A second
opening apparatus 81 placed next to the first opening apparatus 71
has the same arrangement and performs the same operation as the
first opening apparatus 71.
[0054] Numerals shown in the right-top corners in two rectangular
frames in each of FIGS. 10 to 13 indicate the order in which the
suction cups 74 and 75 move to open the bag 72. Regarding the first
apparatus 71, the suction cups 74 and 75 gradually move toward each
other and toward the bag 72 from position "1" to "2" and further to
"3" while rotating in opposite directions to each other. At
position "4", the suction cups 74 and 75 come closest to each other
and abut against each other across the bag 72. Thus, the suction
cups 74 and 75 adhere to the respective outer surfaces of the
opposite side walls of the bag 72 at the fastener (not shown). It
should be noted that the peripheral velocity of the suction cups 74
and 75 at the positions of the suction-adhering surfaces when the
suction cups 74 and 75 rotate about their axes 76 and 77 coincides
with the travel speed of the bag 72. Therefore, there is no
discrepancy between the movement of the suction cups 74 and 75 and
that of the bag 72. Thus, the suction-adhering operation takes
place smoothly. Then, the suction cups 74 and 75 move toward
position "5" while continuing to rotate and moving away from each
other, thereby pulling the bag 72 from both sides thereof. When
they reach position "6", the suction cups 74 and 75 separate from
the bag 72. At this time, a part of the fastener has been
disengaged or has begun to disengage. Then, the suction cups 74 and
75 move from position "7" to "8" where they are remotest from each
other, and then return to position "1". Meanwhile, the bag 72 that
has been treated by the apparatus 71 moves to the position of the
second opening apparatus 81, and a subsequent bag 72 is fed to the
position of the first apparatus 71. The operation of the second
apparatus 81 is the same as that of the apparatus 71. Therefore, a
description thereof is omitted. It should be noted, however, that
the fastener has been partially opened by the first apparatus 71,
or at least a part of the fastener has begun to open. Therefore,
the fastener is fully opened easily and thus the bag 72 is fully
opened by the second apparatus 82 as shown at "7" in FIG. 13. In
this embodiment also, the fastener opening operation and hence the
bag opening operation can be facilitated and ensured effectively by
employing the nozzle used in the first embodiment.
[0055] It should be noted that the present invention is not limited
to the foregoing embodiments but can be modified in a variety of
ways.
* * * * *