U.S. patent application number 12/440692 was filed with the patent office on 2010-02-25 for longitudinal sealing mechanism.
This patent application is currently assigned to ISHIDA CO., LTD.. Invention is credited to Satoshi Hashimoto, Yukio Sasaki, Masahiko Tatsuoka.
Application Number | 20100043352 12/440692 |
Document ID | / |
Family ID | 39282857 |
Filed Date | 2010-02-25 |
United States Patent
Application |
20100043352 |
Kind Code |
A1 |
Hashimoto; Satoshi ; et
al. |
February 25, 2010 |
LONGITUDINAL SEALING MECHANISM
Abstract
A longitudinal sealing mechanism is adapted to seal an
overlapped portion of a packaging material formed into a tubular
shape with the overlapped portion extending along a conveying
direction of the packaging material. The longitudinal sealing
mechanism includes a contact section, a heating section and a
receiving member. The contact section comes into contact with the
overlapped portion of the packaging material. The heating section
heats the contact section to perform longitudinal sealing of the
overlapped portion to form a longitudinal seal portion. The
receiving member abuts against the contact section with the
overlapped portion of the packaging material being disposed
therebetween. The contact section, the heating section, and the
receiving member are arranged such that an amount of heat per unit
time applied to the packaging material from the contact section
decreases in a direction toward both sides of the longitudinal seal
portion.
Inventors: |
Hashimoto; Satoshi; (Shiga,
JP) ; Tatsuoka; Masahiko; (Shiga, JP) ;
Sasaki; Yukio; (Shiga, JP) |
Correspondence
Address: |
GLOBAL IP COUNSELORS, LLP
1233 20TH STREET, NW, SUITE 700
WASHINGTON
DC
20036-2680
US
|
Assignee: |
ISHIDA CO., LTD.
Kyoto
JP
|
Family ID: |
39282857 |
Appl. No.: |
12/440692 |
Filed: |
October 5, 2007 |
PCT Filed: |
October 5, 2007 |
PCT NO: |
PCT/JP2007/069628 |
371 Date: |
March 10, 2009 |
Current U.S.
Class: |
53/375.9 |
Current CPC
Class: |
B29C 66/3472 20130101;
B29C 66/83543 20130101; B29C 66/91212 20130101; B29C 66/849
20130101; B29C 66/91421 20130101; B29C 66/961 20130101; B29C
66/81419 20130101; B29C 66/4322 20130101; B29C 66/112 20130101;
B29C 66/8221 20130101; B65B 51/306 20130101; B65B 9/2021 20130101;
B29C 66/49 20130101; B29C 65/18 20130101; B29C 66/91231 20130101;
B29C 66/83421 20130101; B29C 66/73921 20130101; B29C 66/9192
20130101; B29C 66/135 20130101; B65B 9/207 20130101; B29C 66/8322
20130101; B29C 66/9161 20130101; B65B 51/18 20130101; B29C 66/4312
20130101; B29C 66/81422 20130101; B65B 2051/105 20130101; B29C
66/8222 20130101 |
Class at
Publication: |
53/375.9 |
International
Class: |
B65B 51/10 20060101
B65B051/10 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 13, 2006 |
JP |
2006-280335 |
Claims
1. A longitudinal sealing mechanism adapted to seal an overlapped
portion of a packaging material formed into a tubular shape with
the overlapped portion extending along a conveying direction of the
packaging material, the longitudinal sealing mechanism comprising:
a contact section configured and arranged to come into contact with
the overlapped portion of the packaging material; a heating section
configured and arranged to heat the contact section to perform
longitudinal sealing of the overlapped portion to form a
longitudinal seal portion; and a receiving member configured and
arranged to abut against the contact section with the overlapped
portion of the packaging material being disposed therebetween while
the longitudinal sealing of the overlapped portion; the contact
section, the heating section, and the receiving member being
configured and arranged such that an amount of heat per unit time
applied to the packaging material from the contact section
decreases in a direction toward both sides of the longitudinal seal
portion in a direction perpendicular to the conveying direction of
the packaging material.
2. The longitudinal sealing mechanism according to claim 1, wherein
the heating section and the receiving member each have a width
substantially equal to a width of the longitudinal seal portion
formed on the packaging material, and the contact section has a
width larger than the width of the longitudinal seal portion.
3. The longitudinal sealing mechanism according to claim 1, wherein
the receiving member has a width substantially equal to a width of
the longitudinal seal portion.
4. The longitudinal sealing mechanism according to claim 1, wherein
the receiving member has a convex contact surface configured and
arranged to face the overlapped portion of the packaging material
so that both sides of the receiving member in a width direction are
spaced apart from the contact section.
5. The longitudinal sealing mechanism according to claim 1, wherein
the contact section has a convex surface configured and arranged to
face the overlapped portion of the packaging material so that the
packaging material is spaced apart from the contact section at an
area on an outer side of a contact portion of the contact section
that contacts the longitudinal seal portion.
6. The longitudinal sealing mechanism according to claim 1, wherein
the heating section has a generally T-shape cross sectional shape
in a plane perpendicular to the conveying direction of the
packaging material with a side corresponding to a horizontal line
of the T-shape being disposed adjacently to the contact
section.
7. The longitudinal sealing mechanism according to claim 1, wherein
the contact section has a rotational belt structure that rotates
around the heating section.
8. The longitudinal sealing mechanism according to claim 1, wherein
the contact section is integrally formed with the heating section
to form a heater block member.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This national phase application claims priority to Japanese
Patent Application No. 2006-280335 filed on Oct. 13, 2006. The
entire disclosure of Japanese Patent Application No. 2006-280335
are hereby incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to a longitudinal sealing
mechanism mounted on a bag manufacturing and packaging apparatus
and configured to seal an overlapped portion of a packaging
material formed in a tubular shape while the packaging material is
being conveyed.
BACKGROUND ART
[0003] In recent years, there has been provided a bag manufacturing
and packaging apparatus as a device for bag manufacturing and
packaging, which manufactures bags and fills the inside of these
bags with articles to be packaged such as snack foods. For example,
with a longitudinal bag manufacturing and packaging apparatus
called a pillow packaging apparatus, a packaging material that is a
sheet-like film is formed into a tubular shape by a former and a
tube, and overlapped longitudinal ends of the tubular packaging
material are thermally sealed (thermal welding) to be made into a
tubular packaging material by a longitudinal sealing mechanism.
Then, the articles to be packaged are filled from the tube into the
tubular packaging material which ultimately becomes a bag.
Thereafter, a portion across a top end portion of the bag and a
bottom end portion of the next following bag are thermally sealed
by a transverse sealing mechanism disposed blow the tube, and then
the center of the thermal seal portion (transverse seal portion) is
cut by a cutter.
[0004] With this type of longitudinal sealing mechanism mounted on
the bag manufacturing and packaging apparatus described as above, a
sheet-like packaging material is wrapped around the tube to form
the packaging material into a tubular shape. Then, an overlapped
portion of the tubular packaging material is thermally sealed by
causing a heated heater belt to come into contact with the
overlapped portion and applying heat and pressure thereto. At this
time, as a counterpart of the heater belt to sandwich the
overlapped portion of the packaging material therebetween, the tube
that forms the tubular packaging material is provided with a pad
(receiving member) on the surface facing the heater belt.
[0005] For example, Japanese Patent Application Publication No.
2000-72104 A (published on Mar. 7, 2000) discloses a longitudinal
sealing device including a heat generating protrusion provided at a
heater block and a pair of guide rails provided at an outer surface
of a filling tube, in which an overlapped portion of a packing
material, i.e., a seal portion, is resiliently deformed by the heat
generating protrusion and the guide rails and supported at three
points, and heat is applied intensively to the overlapped portion
from the heat generating protrusion in order to heat seal the
overlapped portion.
DISCLOSURE OF THE INVENTION
[0006] However, the above described conventional longitudinal
sealing mechanism has the following problems.
[0007] Specifically, with the longitudinal sealing mechanism
disclosed in the above publication, because a relatively large
amount of heat is applied also to the surrounding area of the seal
portion, there is a risk that not only the seal portion but also
its surrounding becomes contracted, generating wrinkles.
[0008] An object of the present invention is to provide a
longitudinal sealing mechanism capable of reducing generation of
wrinkles, sealing failure, and the like at a surrounding area of a
longitudinal seal portion.
[0009] A longitudinal sealing mechanism according to a first aspect
of the present invention is a longitudinal sealing mechanism
adapted to seal an overlapped portion of a packaging material
formed into a tubular shape with the overlapped portion extending
along a conveying direction of the packaging material. The
longitudinal sealing mechanism includes a contact section, a
heating section, and a receiving member. The contact section is
configured and arranged to come into contact with the overlapped
portion of the packaging material. The heating section is
configured and arranged to heat the contact section to perform
longitudinal sealing of the overlapped portion to form a
longitudinal seal portion. The receiving member is configured and
arranged to abut against the contact section with the overlapped
portion of the packaging material being disposed therebetween while
the longitudinally sealing of the overlapped portion. Further, the
contact section, the heating section, and the receiving member are
configured and arranged such that an amount of heat per unit time
applied to the packaging material from the contact section
decreases in the direction toward the both sides of the
longitudinal seal portion in the direction perpendicular to the
conveying direction of the packaging material.
[0010] Here, in the longitudinal sealing mechanism which forms a
longitudinal seal portion at the overlapped portion in order to
manufacture a bag, the contact section, the heating section, and
the receiving member which form the longitudinal seal portion are
configured and arranged so that the amount of heat applied to the
packaging material from the contact section decreases in the
direction toward the both sides of the longitudinal seal portion in
the width direction. Specifically, in order to prevent excess heat
from being applied to the peripheral area of the longitudinal seal
portion, for example, a temperature gradient is created in which
the temperature decreases in the direction toward the both sides of
the contact section in the width direction.
[0011] Note that the both sides of the longitudinal seal portion in
the direction crossing the conveying direction of the above
described packaging material refer to both end portions of the
longitudinal seal portion in the width direction.
[0012] Typically, with this type of conventional longitudinal
sealing mechanism, the width of the contact section that comes into
direct contact with the packaging material is set larger than the
width of the longitudinal seal portion such that the longitudinal
seal portion can be formed even when the packaging material is
displaced to the left or right during conveyance. Consequently,
with the conventional longitudinal sealing mechanism, the both
sides of the longitudinal seal portion in the width direction are
subjected to the same amount of heat as the longitudinal seal
portion is and become contracted. This has been a factor in
generating wrinkles and sealing failure.
[0013] With the longitudinal sealing mechanism of the present
invention, the contact section, the heating section, and the
receiving member are configured such that the heat will not be
applied more than necessary to the surrounding area of the
longitudinal seal portion when the heat is applied from the contact
section to the packaging material.
[0014] Accordingly, the amount of heat applied to portions other
than the longitudinally sealed portion of the packaging material
can be reduced compared to the conventional mechanism, and the
necessary amount of heat can be applied only to the longitudinal
seal portion of the packaging material. As a result, it is possible
to prevent the both sides of the longitudinal seal portion from
being excessively heated, and thus generation of problems such as
wrinkles, sealing failure, and the like along the longitudinal seal
portion can be prevented.
[0015] A longitudinal sealing mechanism according to a second
aspect of the present invention is the longitudinal sealing
mechanism according to the first aspect of the present invention,
wherein the heating section and the receiving member each have a
width substantially equal to a width of the longitudinal seal
portion formed on the packaging material. Further, the contact
section has a width larger than the width of the longitudinal seal
portion.
[0016] Here, the widths of the heating section and the receiving
member are made equal to the width of the longitudinal seal
portion, and the width of the contact section is made larger than
the width of the longitudinal seal portion.
[0017] Accordingly, a large amount of heat necessary for
longitudinal sealing is applied to the area of the contact section
where the width is equal to the width of the heating section. At
the same time, the amount of heat is gradually reduced toward the
areas on both sides of the aforementioned area. As a result, the
temperature can be reduced toward the both sides of the contact
section that comes into contact with the packaging material, and
thus it is possible to prevent generation of wrinkles and sealing
failure at the surrounding area of the longitudinal seal
portion.
[0018] A longitudinal sealing mechanism according to a third aspect
of the present invention is the longitudinal sealing mechanism
according to the first aspect of the present invention, wherein the
receiving member has a width substantially equal to the width of
the longitudinal seal portion.
[0019] Here, the width of the receiving member is formed according
to the width of the longitudinal seal portion.
[0020] Accordingly, even when the width of the contact section is
larger than the width of the longitudinal seal portion, only the
longitudinal seal portion is sandwiched between the contact section
and the receiving member and the heat is applied thereto.
Consequently, an outer side of the longitudinal seal portion is
prevented from being directly subjected to a large amount of heat,
and thus generation of wrinkles, sealing failure, and the like
along the longitudinal seal portion can be prevented.
[0021] A longitudinal sealing mechanism according to a fourth
aspect of the present invention is the longitudinal sealing
mechanism according to the first aspect of the present invention,
wherein the receiving member has a convex contact surface
configured and arranged to face the overlapped portion of the
packaging material so that both sides of the receiving member in a
width direction are spaced apart from the contact section.
[0022] Here, the receiving member that sandwiches the packaging
material against the contact section and forms the longitudinal
seal portion is configured such that a contact surface that
contacts the packaging material is formed in a curved shape such
that only the longitudinal seal portion is sandwiched between the
contact section and the receiving member.
[0023] Accordingly, it is possible to reduce the amount of heat
applied to the both sides of the longitudinal seal portion from the
contact section, and the heat can be applied mainly to the
longitudinal seal portion. As a result, it is possible to prevent
excess supply of heat to the surrounding of the longitudinal seal
portion and generation of wrinkles and sealing failure.
[0024] A longitudinal sealing mechanism according to a fifth aspect
of the present invention is the longitudinal sealing mechanism
according to the first aspect of the present invention, wherein the
contact section has a convex surface configured and arranged to
face the overlapped portion of the packaging material so that the
packaging material is spaced apart from the contact section at an
area on an outer side of a contact portion of the contact section
that contacts the longitudinal seal portion.
[0025] Here, the contact section that sandwiches the packaging
material against the receiving member so as to form the
longitudinal seal portion has the curved surface whose distance
from the packaging material increases toward the both side in the
width direction.
[0026] Accordingly, the both sides of the longitudinal seal portion
of the packaging material are prevented from being directly
sandwiched between the contact section and the receiving member. As
a result, it is possible to prevent excess supply of heat to the
surrounding of the longitudinal seal portion and generation of
wrinkles and sealing failure.
[0027] A longitudinal sealing mechanism according to a sixth aspect
of the present invention is the longitudinal sealing mechanism
according to any one of the first through fifth aspects of the
present invention, wherein the heating section has a generally
T-shape cross sectional shape in a plane perpendicular to the
conveying direction of the packaging material with a side
corresponding to a horizontal line of the T-shape being disposed
adjacently to the contact section.
[0028] Here, the contact section is heated by using the heating
section whose cross sectional shape is generally T-shaped. Further,
the contact section is heated by the projection-side surface (the
side corresponding to the horizontal line) of the generally
T-shape.
[0029] Accordingly, in the projecting portion of the generally
T-shaped heating section, because the heat becomes more easily
diffused in the both end portions than in the center portion, it is
possible to create a temperature gradient inclined in the direction
toward the both sides. As a result, it is possible to reduce the
amount of heat applied to the both sides of the longitudinal seal
portion and prevent generation of wrinkles, sealing failure and the
like along both sides of the longitudinal seal portion.
[0030] A longitudinal sealing mechanism according to a seventh
aspect of the present invention is the longitudinal sealing
mechanism according to any one of the first through sixth aspects
of the present invention, wherein the contact section has a
rotational belt structure that rotates around the heating
section.
[0031] Accordingly, it is possible to prevent an excess amount of
heat from being applied to the surrounding of the longitudinal seal
portion from the rotational belt structure, and thus generation of
problems such as wrinkles, sealing failure, and the like along the
longitudinal seal portion can be prevented.
[0032] A longitudinal sealing mechanism according to an eighth
aspect of the present invention is the longitudinal sealing
mechanism according to any one of the first through sixth aspects
of the present invention, wherein the contact section is integrally
formed with the heating section to form a heater block member.
[0033] Accordingly, it is possible to prevent an excess amount of
heat from being applied to the surrounding of the longitudinal seal
portion from the heater block member, and thus problems such as
generation of wrinkles, sealing failure, and the like along the
longitudinal seal portion can be prevented.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] FIG. 1 is a schematic perspective view of a bag
manufacturing and packaging apparatus equipped with a longitudinal
sealing mechanism according to an embodiment of the present
invention.
[0035] FIG. 2 is an enlarged view showing the longitudinal sealing
mechanism included in the bag manufacturing and packaging apparatus
in FIG. 1.
[0036] FIG. 3 is a cross sectional view taken along an arrow A-A in
FIG. 2.
[0037] FIG. 4 is a lateral view showing the longitudinal sealing
mechanism in FIG. 2.
[0038] FIG. 5 is an elevational view showing the longitudinal
sealing mechanism in FIG. 2.
[0039] FIG. 6 is an elevation view showing the shape of a pulley
included in the longitudinal sealing mechanism in FIG. 2.
[0040] FIG. 7 is a schematic view showing a transverse sealing
mechanism included in the bag manufacturing and packaging apparatus
in FIG. 1.
[0041] FIG. 8 is a graph showing an example of a widthwise
temperature distribution of a heater belt included in the
longitudinal sealing mechanism in FIG. 2.
[0042] FIG. 9 is a cross sectional view showing a configuration of
a longitudinal sealing mechanism according to another embodiment of
the present invention.
[0043] FIGS. 10(a) and 10(b) are cross sectional views showing the
cross sectional shape of a receiving member included in a
longitudinal sealing mechanism according to yet another embodiment
of the present invention.
[0044] FIG. 11 is a cross sectional view showing the cross
sectional shapes of a heater belt and a heater block included in a
longitudinal sealing mechanism according to yet another embodiment
of the present invention.
[0045] FIG. 12 is a cross sectional view showing the cross
sectional shapes of a heater belt and a heater block included in a
longitudinal sealing mechanism according to yet another embodiment
of the present invention.
[0046] FIG. 13 is a cross sectional view showing the cross
sectional shape of a heater block member included in a longitudinal
sealing mechanism according to yet another embodiment of the
present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0047] A bag manufacturing and packaging apparatus 1 equipped with
a longitudinal sealing mechanism 15 according to an embodiment of
the present invention is described with reference to FIGS. 1
through 8.
Overall Structure of Bag Manufacturing and Packaging Apparatus
1
[0048] As shown in FIG. 1, the bag manufacturing and packaging
apparatus 1 according to an embodiment of the present invention is
an apparatus that encloses articles C (here, potato chips) such as
potato chips in a thermoplastic film (packaging material) F, and
manufactures a bag by transversely and longitudinally sealing the
film F made into a tubular shape.
[0049] In this embodiment, the bag manufacturing and packaging
apparatus 1 is configured and arranged to receive potato chips of a
predetermined amount that is discharged from a weighing device and
the like disposed above the bag manufacturing and packaging
apparatus 1.
[0050] The bag manufacturing and packaging apparatus 1 includes a
bag manufacturing unit 10, a control unit 20, and a film roll
holder (not shown).
Film Roll Holder
[0051] The film roll holder holds a film roll from which a
sheet-like film F is unwound and sent to a former 13a of the later
described bag manufacturing unit 10. The film roll is formed by
winding the long film F. The tension of the film F unwound from
this film roll is maintained in a predetermined range by a dancer
roller or the like in order to prevent loosening and meandering
during conveyance.
[0052] In addition, a film remaining amount detection sensor (not
shown) that detects the remaining amount of the film F wound around
the film roll is disposed in the vicinity of the film roll
holder.
Bag Manufacturing Unit 10
[0053] As shown in FIG. 1, the bag manufacturing unit 10 includes:
a forming mechanism 13 that forms the sheet-like film F sent from
the film roll holder into a tubular shape; a pull-down belt
mechanism 14 that conveys the tube-like film F (hereinafter
referred to as "tubular film") downward; the longitudinal sealing
mechanism 15 that longitudinally seals an overlapped portion of the
tubular film; and a transverse sealing mechanism 17 that
transversely seals the tubular film and thereby seals the upper and
lower ends of a bag B.
Forming Mechanism 13
[0054] The forming mechanism 13 includes a tube 13b, the former
13a, and a surface fastener (receiving member) 13c. Note that,
here, the surface fastener 13c is described as a part of the
forming mechanism 13, however, it can be regarded as a part of the
later described longitudinal sealing mechanism 15.
[0055] The tube 13b is a cylindrical shaped member whose upper and
lower ends are open. The potato chips C weighed by the weighing
device are fed into the opening at the upper end of the tube 13b.
In addition, the tube 13b includes the surface fastener 13c on the
surface facing a heater belt 16a of the later described
longitudinal sealing mechanism 15. Further, an overlapped portion
F2 (see FIG. 3) of the film F is sandwiched between the surface
fastener 13c and the heater belt 16a, and the overlapped portion F2
is thereby sealed.
[0056] The former 13a is disposed so as to surround the tube 13b.
The shape of the former 13a is formed such that the sheet-like film
F unwound and sent from the film roll is formed into a tubular
shape when passing through the former 13a and the tube 13b.
[0057] In addition, the tube 13b and the former 13a of the forming
mechanism 13 can be replaced according to the size of the bags to
be manufactured.
[0058] As shown in FIGS. 3 through 5, the surface fastener 13c is
detachably and replaceably attached to a flat portion of the
surface of the tube 13b, in which the flat portion faces the heater
belt 16a of the longitudinal sealing mechanism 15. The surface
fastener 13c is disposed in a prescribed position so that heat and
pressure is applied to the overlapped portion of the film between
the surface fastener 13c and the heater belt 16a and the overlapped
portion is sealed. Note that, in view of improvement of sealing
performance, as the surface fastener 13c, it is preferable to use a
small member such as VELCRO (registered trademark), MAGIC TAPE
(registered trademark), or the like, for example, which has
elasticity in the direction of contact with the film F and whose
contact surface has small frictional resistance. In addition, as
shown in FIG. 3, the surface fastener 13c has a width d1
substantially equal to a width d (see FIG. 2) of a longitudinal
seal portion F1 of the film F in the plane view, and forms the
longitudinal seal portion F1 within this width. Accordingly, when
the longitudinal seal portion F1 is formed on the film F, the
sealing process is performed by sandwiching an overlapped portion
F2 of the film F between the surface fastener 13c having a width
substantially equal to the width d of the longitudinal seal portion
F1 and the heater belt 16a. Thereby, even when a width d2 of the
heater belt 16a is larger than the width d of the longitudinal seal
portion F1, heat can be applied intensively to the longitudinal
seal portion F1 to accomplish the sealing process.
Pull-Down Belt Mechanism 14
[0059] The pull-down belt mechanism 14 is a mechanism that holds
the tubular film wound around the tube 13b by suction-adhesion and
conveys the same downward. As shown in FIGS. 1 and 5, the pull-down
belt mechanism 14 is provided with a belt 14c on each of the left
and right sides of the tube 13b. The pull-down belt mechanism 14
rotates the belts 14c having the suction-adhesion function by a
driving roller 14a and a driven roller 14b and conveys the tubular
film downward. Note that, in FIGS. 1 and 5, the drawing of a roller
driving motor that rotates the driving roller 14a and the like is
omitted.
Longitudinal Sealing Mechanism 15
[0060] As shown in FIG. 1, the longitudinal sealing mechanism 15 is
a mechanism that presses, with a constant amount of pressure, the
overlapped portion F2 (see FIG. 3) of the tubular film F wound
around the tube 13b onto the surface fastener 13c portion attached
to the tube 13b, applies heat and pressure thereto, and thereby
forms the longitudinal seal portion F1 (see FIGS. 1 and 2) along
the longitudinal direction (conveying direction). In addition, the
longitudinal sealing mechanism 15 is disposed on the front side of
the tube 13b, and is connected to the control unit 20. In addition,
as shown in FIG. 2, the longitudinal sealing mechanism 15 includes
the heater belt (contact section, rotational belt structure) 16a, a
heater block (heating section) 16b and a pulley 16c.
[0061] As shown in FIG. 2, the heater belt 16a is an annularly
formed (ring-like) metal belt with a thickness of approximately
0.15 mm. The heater belt 16a is held in a state of maintaining a
substantially constant amount of tensional force by the two pulleys
16c disposed in contact with the inner surface of the heater belt
16a. The heater belt 16a is rotated in the longitudinal direction
when the pulleys 16c rotate. The heater belt 16a comes into contact
with the overlapped portion F2 (see FIG. 3) of the film F in a
manner of sandwiching the tubular film F being conveyed at
substantially the same speed as the rotation speed of the heater
belt 16a between the heater belt 16a and the tube 13b (surface
fastener 13c); applies pressure and heat to the overlapped portion
F2 in the space between the heater belt 16a and the surface
fastener 13c; and thereby longitudinally seals the overlapped
portion F2. In addition, as shown in FIG. 3, the heater belt 16a
has the width d2 larger than the width d1 of the surface fastener
13c and a width d3 of the heater block 16b which are the widths
substantially equal to the width d of the longitudinal seal portion
F1. Consequently, as shown in FIG. 8, on the heater belt 16a that
comes into direct contact with the overlapped portion F2 of the
film F, a temperature gradient is created in which the temperature
decreases from the center portion, where the heater block 16b is
adjacently disposed, toward the both sides. Accordingly, a
sufficient amount of heat and pressure per unit time to perform
sealing can be applied to the longitudinal seal portion F1 of the
film F, whereas a smaller amount of heat and pressure can be
applied to the area surrounding the longitudinal seal portion F1.
As a result, it is possible to prevent an excess amount of heat per
unit time from being applied to the surrounding of the longitudinal
seal portion F1 of the film F due to the contact with the heater
belt 16a, and thus generation of wrinkles and sealing failure along
the longitudinal seal portion F1 can be prevented.
[0062] As shown in FIGS. 2 through 4, the heater block 16b is a
rectangular parallelepiped shaped metal block, and has a built-in
heater bar 16e that generates heat, on the side where the heater
belt 16a and the film F come into contact with each other. Further,
the heater block 16b is adjacently disposed to the inner side of
the heater belt 16a along the surface of the heater belt 16a in the
longitudinal direction, and heats the heater belt 16a to 140 to 150
degrees C. Note that the heater bar 16e is not built in on the back
side of the heater block 16b, but the entire heater block 16b is
made of a metal having a high thermal conductivity, so that the
temperature on the back side is also heated to about 130 degrees C.
In addition, as shown in FIG. 3, similar to the surface fastener
13c, the heater block 16b has the width d3 (.apprxeq.d1)
substantially equal to the width d (see FIG. 2) of the longitudinal
seal portion F1 of the film F in the plane view. Consequently, from
the heater block 16b to the heater belt 16a, a sufficient amount of
heat to perform the sealing process is applied only to the portion
within the width d of the longitudinal seal portion F1. On the
other hand, because the heater block 16b is not adjacently disposed
in the areas on the outer sides of the portion of the heater belt
16a corresponding to the width d of the longitudinal seal portion
F1, the amount of heat applied to the areas on the outer sides is
significantly reduced. Thus, the temperature gradient is created in
which the temperature decreases from the center to the both sides
on the surface of the heater belt 16a (see the graph in FIG.
8).
[0063] As shown in FIGS. 2 and 4, the two pulleys 16c are disposed
on the inner side of the heater belt 16a. The transmitted torque
from a motor (not shown) causes the pulleys 16c to rotate about a
rotation shaft 16f (see FIG. 6), which consequently rotates the
heater belt 1 6a in the longitudinal direction.
[0064] Note that the inner side of the heater belt 16a refers to
the surface inside the endless belt supported by the pulleys 16c,
and the outer side of the heater belt 16a refers to the surface on
the side where longitudinal sealing is performed by being brought
into contact with the film F. In addition, the back side of the
heater block 16b refers to the side opposite to the side where the
heater bar 16e is built in and longitudinal sealing is
performed.
Transverse Sealing Mechanism 17
[0065] The transverse sealing mechanism (transverse seal portion)
17 is disposed below the forming mechanism 13, the pull-down belt
mechanism 14, and the longitudinal sealing mechanism 15. The
transverse sealing mechanism 17 has a pair of sealing jaws 51 each
with a built-in heater (see FIG. 7). One of the pair of sealing
jaws 51 is located at the front side of the tubular film and the
other one at the back side thereof, and as shown in FIG. 7, they
circulate so as to produce generally D-shaped trajectories T that
are front-to-back symmetric. Further, in the course of the
circulatory movement, the tubular film is sandwiched between the
pair of sealing jaws 51 as they push against each other. The
sealing jaws 51 apply pressure and heat to a portion of the tubular
film which becomes the upper and lower ends of a bag in order to
seal the portion. One of the sealing jaws 51 located at the front
side of the tubular film is supported by a shaft 17c so as to
rotate about the shaft 17c. The shaft 17c is rotated via a gear by
the operation of a motor for circulation (not shown) and is also
horizontally moved front to back via a ball screw mechanism (not
shown) by the operation of a motor for movement of the shaft. In
addition, similarly, one of the sealing jaws 51 located at the back
side of the tubular film is also rotated via a gear by the
operation of the motor for circulation and is also horizontally
moved front to back by the operation of the motor for movement of
the shaft. In this way, as the pair of sealing jaws 51 is rotated
and horizontally moved, the generally D shaped trajectories T of
the sealing jaws 51 are produced. In addition, through the torque
control of the motor for movement of the shaft, the pressure at the
time when the pair of sealing jaws 51 sandwiches the tubular film
therebetween is adjusted.
[0066] In addition, a cutter (not shown) is built-in in one of the
pair of sealing jaws 51. This cutter fulfills the role to cut off
the bag B from the following tubular film at the central position
in the height direction of the transverse seal portion formed by
the sealing jaws 51.
Control Unit 20
[0067] As shown in FIG. 1, the control unit 20 is connected to the
longitudinal sealing mechanism 15 and other components of the bag
manufacturing and packaging apparatus 1. Further, the control unit
20 is connected to the heater block 16b (heater bar 16e) included
in the longitudinal sealing mechanism 15. In accordance with a
detection result of a temperature sensor (not shown) that detects
the temperature of the heater block 16b, the control unit 20
adjusts the amount of heat applied to the heater belt 16a from the
heater bar 16e (heater block 16b), in other words, the control unit
20 controls the set temperature of the heater block 16b, and also
controls the operation of the entire bag manufacturing and
packaging apparatus 1.
Characteristics of Bag Manufacturing and Packaging Apparatus 1
[0068] (1) With the bag manufacturing and packaging apparatus 1 in
this embodiment, as shown in FIG. 3 and the like, the heater belt
16a and the heater block 16b which constitute the longitudinal
sealing mechanism 15 and the surface fastener 13c disposed on the
forming mechanism 13 side are disposed such that the amount of heat
per unit time applied to the areas on both outer sides of the
longitudinal seal portion F1 of the film F is reduced.
[0069] Accordingly, while a sufficient amount of heat and pressure
to perform the sealing process are applied to the longitudinal seal
portion F1 of the film F, it is possible to prevent an excess
amount of heat from being applied to the areas on both outer sides
of the longitudinal seal portion F1. As a result, it is possible to
prevent degradation of the appearance of the product caused by
generation of wrinkles and the like along the longitudinal seal
portion F1 which occurs when an amount of heat and pressure per
unit time necessary for the sealing process are applied also to the
surrounding of the longitudinal seal portion F1.
[0070] (2) With the bag manufacturing and packaging apparatus 1 in
this embodiment, as shown in FIG. 3, as the constituent members
that apply the amount of heat and pressure to the longitudinal seal
portion F1 of the film F to perform the sealing process, the
surface fastener 13c and the heater block 16b respectively having
the width d1 and the width d3 substantially equal to the width d of
the longitudinal seal portion F1, and the heater belt 16a having
the width d2 larger than those widths d, d1, and d3 are used.
[0071] Accordingly, on the longitudinal seal portion F1 of the film
F which is sandwiched between the surface fastener 13c and the
heater belt 16a, a large amount of heat and pressure are applied to
the area within the width d1 of the surface fastener 13c. On the
other hand, although the areas on both outer sides of the width d1
come into contact with the heater belt 16a having the width wider
than the surface fastener 13c, the amount of heat and pressure
necessary to perform the sealing process are not applied thereto
because the temperature gradient as shown in FIG. 8 is created on
the heater belt 16a in the width direction and the surface fastener
13c as a counterpart of the heater belt 16a to sandwich the film F
therebetween is not present on the heater belt 16a. In particular,
in the areas on both outer sides of the surface fastener 13c, the
film F wound around the tube 13b whose cross sectional shape is
generally circular comes off from the surface of the heater belt
16a, so that the amount of heat and pressure are prevented from
being excessively applied to the film F.
[0072] As a result, it is possible to prevent generation of
wrinkles and the like along the longitudinal seal portion F1 which
occurs when an excess amount of heat and pressure are applied to
the both outer sides of the longitudinal seal portion F1 from the
heater belt 16a, and thus degradation of the appearance of the
product can be prevented.
[0073] (3) With the bag manufacturing and packaging apparatus 1 in
this embodiment, as shown in FIG. 3, the surface fastener 13c has
the width substantially equal to the width d of the longitudinal
seal portion F1.
[0074] Accordingly, because the surface fastener 13c facing the
heater belt 16a is not present in the areas on both outer sides of
the longitudinal seal portion F1, the amount of heat and pressure
per unit time applied to the film F from the heater belt 16a are
significantly lower in the areas on both outer sides than in the
area of the longitudinal seal portion F1.
[0075] In particular, in the areas on both outer sides of the
surface fastener 13c, the film F wound around the tube 13b whose
cross sectional shape is generally circular comes off from the
surface of the heater belt 16a. Thus, the amount of heat and
pressure are not excessively applied to the film F.
[0076] As a result, it is possible to prevent generation of
wrinkles and the like along the longitudinal seal portion F1 which
occurs when the same amount of heat and pressure that are applied
to perform the sealing process are applied to the both outer sides
of the longitudinal seal portion F1 from the heater belt 16a, and
thus degradation of the appearance of the product can be
prevented.
Other Embodiments
[0077] An embodiment of the present invention has been described as
above, however, the present invention is not limited to the above
embodiment, and various changes and modifications can be made
herein without departing from the scope of the invention.
[0078] (A) The above embodiment is described, as shown in FIG. 3,
taking an example in which the width d1 of the surface fastener 13c
and the width d3 of the heater block 16b are set substantially
equal to the width d (see FIG. 2) of the longitudinal seal portion
F1, and the width d2 of the heater belt 16a is set larger than
these widths d, d1, and d3. However, the present invention is not
limited thereto.
[0079] For example, as shown in FIG. 9, the width d1 of the surface
fastener 13c may be set substantially equal to the width d of the
longitudinal seal portion F1, and the width d2 of the heater belt
16a and a width d4 of a heater block 116b may be set larger than
these widths d and d1.
[0080] Also in this case, because the width d1 of the surface
fastener 13c is set substantially equal to the width d of the
longitudinal seal portion F1, the width of the overlapped portion
F2 sandwiched between the heater belt 16a and the surface fastener
13c is substantially equal to the width d of the longitudinal seal
portion F1. As a result, because the amount of heat is locally
applied to the portion corresponding to the longitudinal seal
portion F1 from the heater belt 16a, generation of problems such as
wrinkles, sealing failure, and the like in the surrounding of the
longitudinal seal portion can be prevented, and thus the same
effect as described above can be obtained.
[0081] However, in view of the fact that creating the above
described temperature gradient on the surface temperature of the
heater belt 16a can prevent the amount of heat per unit time from
being excessively applied to portions other than the longitudinal
seal portion F1, it is preferred that the width d3 of the heater
block is set substantially equal to the width d of the longitudinal
seal portion F1, as is the case with the above embodiment.
[0082] (B) The above embodiment is described taking an example in
which the surface fastener 13c whose contact surface that contacts
the film F is flat is used as the receiving member that sandwiches
the overlapped portion F2 of the film F against the heater belt 16a
and performs the sealing process. However, the present invention is
not limited thereto.
[0083] For example, as shown in FIG. 10(a), a surface 113ca
corresponding to the contact surface that contacts the film may be
formed in a curved convex shape, as the cross sectional shape of a
surface fastener 113c, and the overlapped portion F2 of the film F
may be sandwiched between this curved surface 113ca and the heater
belt 16a for the sealing process. By providing the convex surface,
both sides of the surface fastener 113c is spaced apart from the
heater belt 16a when the surface fastener 113c abuts against the
heater belt 16a with the film F being disposed therebetween.
[0084] In this case, a sufficient amount of heat and pressure per
unit time are applied to the film F in the area near the center
portion corresponding to the width d of the longitudinal seal
portion F1, and at the same time, it is possible to reduce the
pressure applied to the areas on the outer side of the longitudinal
seal portion F1. As a result, it is possible to prevent an excess
amount of heat and pressure from being applied to the surrounding
areas of the longitudinal seal portion F1 of the film F by the
shape of the surface fastener 113c, regardless of the width of the
heater belt and the heater block that the surface fastener 113c
faces. Thus, generation of wrinkles and sealing failure in the
surrounding of the longitudinal seal portion can be easily
prevented by a simple configuration.
[0085] Further, as the convex cross sectional shape of the
receiving member, as shown in FIG. 10(b), the center portion of the
curved surface 113ca of the surface fastener 113c may be formed as
a flat surface 213ca, and curved surfaces 213cb may be formed on
both sides of the flat surface 213ca.
[0086] In this case, the amount of heat and pressure can be evenly
applied to the area having a width corresponding to the
longitudinal seal portion F1, and at the same time, the amount of
heat and pressure applied to the surrounding areas on both sides
can be reduced. Thus, generation of wrinkles and sealing failure in
the surrounding of the longitudinal seal portion can be easily
prevented by a simple configuration.
[0087] (C) The above embodiment is described taking an example in
which a generally rectangular parallelepiped heating element is
used as the heater block 16b disposed adjacently to the heater belt
16a. However, the present invention is not limited thereto.
[0088] For example, as shown in FIG. 11, a heater block 116c whose
cross sectional shape is generally T-shaped may be used, and a
portion 116ca whose width of the generally T-shape is wider (i.e.,
the side corresponding to the horizontal like of the T-shape) may
be disposed adjacent to the heater belt 16a on the side that comes
into contact with the overlapped portion F2 of the film F.
[0089] In this case, with the portion 116ca whose width is wider,
the temperature at both ends that are not continuous with a portion
116cb on the narrow width side tends to be lower than the
temperature at the center portion. Consequently, a temperature
gradient in which the temperature is reduced from the center
portion to the both ends can be created on the generally T-shaped
heater block 116c. As a result, generation of wrinkles, sealing
failure, and the like in the surrounding of the longitudinal seal
portion can be easily prevented by a simple configuration.
[0090] (D) The above embodiment is described taking an example in
which the heater belt whose contact surface that contacts the film
F is flat is used as the heater belt 16a that sandwiches the
overlapped portion F2 of the film F against the surface fastener
13c as the receiving member and performs the sealing process.
However, the present invention is not limited thereto.
[0091] For example, as shown in FIG. 12, the heater belt 16a whose
surface on the side that comes into contact with the overlapped
portion F2 of the film F is formed as a curved surface 116aa may be
used.
[0092] In this case, the amount of heat and pressure per unit time
applied to the film F from the center portion of the curved surface
116aa can be made larger than the amount of heat and pressure
applied to the both ends thereof. As a result, by positioning the
center portion of the longitudinal seal portion based on the center
portion of the curved surface 116aa, while a sufficient amount of
heat and pressure are applied to the longitudinal seal portion,
such sufficient amount of pressure can be prevented from being
applied to the surrounding areas at both ends of the longitudinal
seal portion.
[0093] Further, as is the case with a surface fastener 213c in FIG.
10(b), the heater belt 16a having a flat surface formed in the
vicinity of the center portion of the curved surface may also be
used.
[0094] (E) The above embodiment is described taking an example in
which the sealing process is performed in a manner that the
overlapped portion F2 of the film F is sandwiched between the
surface fastener 13c and the heater block 16b. However, the present
invention is not limited thereto.
[0095] As a mode to perform the sealing process, for example, the
sealing process may be performed in a manner that the seal portion
is sandwiched by fins. Also, as the overlapped portion, a portion
where films simply overlap with each other without having a folded
portion formed thereon may be subjected to the sealing process.
[0096] (F) The above embodiment is described taking an example in
which the surface fastener 13c that sandwiches the overlapped
portion F2 of the film F against the beater belt 16a is disposed on
the forming mechanism 13 side instead of the longitudinal sealing
mechanism 15 side. However, the present invention is not limited
thereto.
[0097] Because the surface fastener is an element used during the
longitudinal sealing process according to the illustrated
embodiments, it can be considered as a part of the longitudinal
sealing mechanism 15.
[0098] (G) The above embodiment is described taking an example in
which the heater belt 16a is used as the contact section that comes
into contact with the longitudinal seal portion of the film F and
thermally seals the portion. However, the present invention is not
limited thereto.
[0099] For example, as shown in FIG. 13, it may be a type of
longitudinal sealing mechanism in which a heater block member 216b
integrally formed with the heating section of the heater and the
like is intermittently operated in a manner that a contact surface
(contact section) formed on the heater block member 216b is pressed
against the overlapped portion F2 of the film F so as to
longitudinally seal the portion.
[0100] The longitudinal sealing mechanism according to the
illustrated embodiments is capable of preventing the both sides of
the longitudinal seal portion from being excessively heated, so
that the effect of preventing generation of problems such as
wrinkles, sealing failure, and the like along the longitudinal seal
portion is obtained. Thus, the longitudinal sealing mechanism
according to the illustrated embodiments is widely applicable to
various types of sealing devices that perform sealing while
conveying packaging materials.
* * * * *