U.S. patent application number 10/782334 was filed with the patent office on 2004-10-21 for bag sealing apparatus.
This patent application is currently assigned to Toyo Jidoki Co., Ltd.. Invention is credited to Hiramoto, Shinichi, Tsutsui, Shoji.
Application Number | 20040206049 10/782334 |
Document ID | / |
Family ID | 32767680 |
Filed Date | 2004-10-21 |
United States Patent
Application |
20040206049 |
Kind Code |
A1 |
Hiramoto, Shinichi ; et
al. |
October 21, 2004 |
Bag sealing apparatus
Abstract
A bag sealing apparatus including a receiving member 34 attached
to a fixed plate 31 and a sealing member (heating plate) 33
attached to a movable plate 32 that is disposed beneath the fixed
plate 31. The upward and downward movement of the movable plate 32
is guided by the guide shafts 35. A plurality of rubber tubes 36
are connected between the fixed plate 31 and movable plate 32. The
rubber tubes 36 expand in the radial direction and contract in
length when compressed air is supplied and recover to their
original state when the compressed air is discharged; accordingly,
the movable plate 32 is moved to and from the fixed plate 31, and
at the same time, the heating plates 33 and 34 are separated from
and contacted with each other.
Inventors: |
Hiramoto, Shinichi;
(Iwakuni-shi, JP) ; Tsutsui, Shoji; (Iwakuni-shi,
JP) |
Correspondence
Address: |
KODA & ANDROLIA
2029 CENTURY PARK EAST
SUITE 1430
LOS ANGELES
CA
90067-3024
US
|
Assignee: |
Toyo Jidoki Co., Ltd.
|
Family ID: |
32767680 |
Appl. No.: |
10/782334 |
Filed: |
February 17, 2004 |
Current U.S.
Class: |
53/373.7 |
Current CPC
Class: |
B29C 66/3452 20130101;
B29C 66/43121 20130101; B29C 66/91423 20130101; B29C 66/81457
20130101; B29C 66/8122 20130101; B29C 65/08 20130101; B29C 66/8322
20130101; B29C 65/305 20130101; B29C 65/7882 20130101; B29C
66/91431 20130101; B29C 66/9241 20130101; B29C 66/0342 20130101;
B29C 66/8163 20130101; B29C 66/431 20130101; B29C 65/18 20130101;
B29C 66/91645 20130101; B29C 66/1122 20130101; B29C 66/92611
20130101; B65B 9/08 20130101; B29C 66/849 20130101; B29C 66/8161
20130101; B29C 66/4312 20130101; B29C 66/8167 20130101; B29C 66/244
20130101; B65B 51/225 20130101; B29C 66/8122 20130101; B29K 2883/00
20130101 |
Class at
Publication: |
053/373.7 |
International
Class: |
B65B 051/10 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 17, 2003 |
JP |
2003-37613 |
Claims
1. A bag sealing apparatus comprising: a sealing member and a
receiving member that are provided so as to face each other, said
sealing member and receiving member being able to open and close
and are constantly urged in a direction to open, and a driving
means that closes said sealing member and receiving member; wherein
said driving means is comprised of rubber tubes in which said
rubber tubes expand in a radial direction thereof and contract in
length thereof when compressed air is supplied thereto, and said
rubber tubes recover to its original state when said compressed air
is discharged, and said rubber tubes are connected to said sealing
member and receiving member so that said sealing member and
receiving member close when said rubber tubes contract in length
thereof.
2. A bag sealing apparatus comprising: a pair of plates which are
disposed parallel to each other so as to be separated by a
specified distance, said pair of plates being approachable each
other in relative terms from separated positions and constantly
urged in a direction that separates said pair of plates, a sealing
member and a receiving member which are respectively attached to
said pair of plates so as to face each other, a plurality of guide
shafts which are disposed perpendicular to said pair of plates and
guide a relative approach and separation of said pair of plates,
and a driving means which closes said sealing member and receiving
member by causing said pair of plates to approach each other;
wherein said driving means is comprised of a plurality of rubber
tubes in which said rubber tubes expand in a radial direction
thereof and contract in length thereof when compressed air is
supplied thereto and recover to original states thereof when said
compressed air is discharged, and said rubber tubes are connected
to said pair of plates so that said pair of plates approach each
other when said rubber tubes contract in length.
3. A bag sealing apparatus comprising: a fixed plate, a movable
plate which is disposed parallel to said fixed plate so that said
movable plate is separated from said fixed plate by a specified
distance, said movable plate being approachable said fixed plate
from a separated position and constantly urged in a direction that
separates said movable plate from said fixed plate, a sealing
member and a receiving member which are respectively attached to
said movable and fixed plates so as to face each other, a plurality
of guide shafts which are disposed perpendicular to said movable
plate and guide a movement of said movable plate, and a driving
means which closes said sealing member and receiving member by
causing said movable plate to approach said fixed plate; wherein
said driving means is comprised of a plurality of rubber tubes in
which said rubber tubes expand in a radial direction thereof and
contract in length thereof when compressed air is supplied thereto
and recover to original states thereof when said compressed air is
discharged, one end of each one of said rubber tubes is connected
to said movable plate side while another end of said one of said
rubber tubes is connected to said fixed plate side, and said
movable plate is caused to approach said fixed plate when said
rubber tubes contract in length.
4. The bag sealing apparatus according to claim 3, wherein said
sealing member and receiving member comprise heating plates of a
heat sealing system, a surface temperature of said heating plate on
said receiving member side is lower than a surface temperature of
said heating plate on said sealing member side, said receiving
member is attached to said fixed plate, and said sealing member is
attached to said movable plate.
5. The bag sealing apparatus according to claim 1, wherein said
sealing member and said receiving member are urged in said
direction to open by a biasing force of a spring.
6. The bag sealing apparatus according to any one of claims 2
through 4, wherein said pair of plates are urged by one of gravity
and a biasing force of a spring in a direction that separates said
plates.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a bag sealing apparatus
such as a bag sealing apparatus in a bag-making machine or a bag
mouth sealing apparatus in a bag-filling packaging machine,
etc.
[0003] 2. Prior Art
[0004] A bag sealing apparatus in bag-making machines and a bag
mouth sealing apparatus in bag-filling packaging machines perform
sealing by holding specified locations on the bag (for example,
both side portions and the bottom in the case of a bag-making
machine, or the bag mouth in the case of a bag-filling packaging
machine) using a pair of sealing means (sealing member and
receiving member) that are disposed facing each other. As is
generally known, the sealing systems used include a heat sealing
system in which bags are held by a pair of heating plates which
contain heaters and are disposed to face each other, an impulse
sealing system in which bags are held by a heater block that
contains heater wires and a receiving block which is disposed
facing the heater block, and an ultrasonic sealing system in which
bags are held by a horn that vibrates ultrasonically and an anvil
that is disposed facing this horn.
[0005] Furthermore, a means that uses an air cylinder and a means
that uses a cam are commonly employed as the driving means used to
cause the sealing member and receiving member to approach and
separate from each other. For example, air cylinders are used in
Japanese Utility Model Registration Nos. 2600077 and 2607484, while
in Japanese Utility Model Registration No. 2605892, the
raising-and-lowering device that raises and lowers the driving
shaft 11 (paragraph 0011 in the same reference) appears to be a cam
that is rotated by the driving source of the bag-filling packaging
machine.
[0006] However, the following problems have been respectively
encountered in sealing apparatuses that use air cylinder and cams
as a driving means:
[0007] (1) From the standpoint of improving productivity, it is
generally desirable that it be possible to increase the operating
speed (opening-and-closing speed) of the sealing means to a high
speed. However, if the drop in performance and decrease in the
useful life caused by wear of the sealing means, and the
deterioration in the working environment caused by the generation
of impact noise, are taken into consideration, it is desirable that
the operating speed at the instant at which the sealing means
closes be on the small side. However, in the case of an air
cylinder, the speed tends to be more or less constant during the
entire stroke, or to rise in the final stage of the stroke, so that
it is difficult to realize the above-described operating
characteristics. Furthermore, if the operating speed is increased,
the impact noise of the air cylinder itself becomes severe.
[0008] (2) If the production rate of a bag-making machine or
bag-filling packaging machine is varied, the operating speed of the
sealing means also varies. However, from the standpoint of the
quality of the sealed portions, it is desirable that the time for
which the bags are held or pressed by the sealing means (i.e., the
sealing time) be constant regardless of the operating speed of the
sealing means. In the case of cam driving, however, the sealing
time varies when the operating speed is varied; accordingly,
changes in the production rate of the bag-making machine or
bag-filling packaging machine cannot be adequately handled.
[0009] (3) If an attempt is made to obtain a high sealing pressure
using the sealing means, an increase in the size of the sealing
apparatus is unavoidable. For example, in the case of cam driving,
numerous levers or links are interposed between the driving source
and the sealing means; accordingly, a strong frame structure that
supports these levers or links is required. The structure is also
complicated, and inferior in terms of cost, cleaning
characteristics and maintenance. In the case of air cylinder
driving, a large-diameter cylinder is required.
SUMMARY OF THE INVENTION
[0010] The present invention is to solve such problems encountered
in conventional sealing apparatuses used in bag-making machines or
bag-filling packaging machines.
[0011] The main object of the present invention is: to make it
possible to slow the operating speed at the instant of closing of
the sealing means compared to the operating speed in the stroke up
to this point, even in cases where the overall operating speed of
the sealing means is large, to prevent a drop in performance and
decrease in useful life caused by wear of the sealing means, and a
deterioration in the working environment caused by the generation
of impact noise, and to make it possible to maintain the sealing
time at a constant time even if the production rate of the
bag-making machine or bag-filling packaging machine varies, so that
a high sealing quality is obtained.
[0012] It is a further object of the present invention to make it
possible to realize a high sealing pressure without increasing the
size of the sealing apparatus.
[0013] The above objects are accomplished by the unique structure
of the present invention for a bag sealing apparatus in which the
apparatus comprises a sealing member and receiving member that can
open and close (or can be separated from and come into contact with
each other) and that are constantly urged in the direction to open
(or opposing directions), and a driving means that closes (or
contacts) the sealing member and receiving member; and the above
driving means comprises rubber tubes which expand in the radial
direction and contract in length when compressed air is supplied,
and which recover to its original state when this compressed air is
discharged, and the rubber tubes are connected to the sealing
member and receiving member so that the sealing member and
receiving member close (or come into contact with each other) when
the length of the rubber tubes contracts.
[0014] When compressed air is supplied to the interior of the
rubber tubes, the rubber tubes expand in the radial direction, and
the length of the rubber tubes contracts. In this case, tension is
generated in the axial direction in accordance with the amount of
contraction. However, when the compressed air is discharged so that
the rubber tubes recover to their original state (i.e., when the
rubber tubes contract in the radial direction and the length of the
tubes is extended), there is substantially no generation of any
force in the opposite direction. Accordingly, the tension that is
generated when the length of the rubber tubes contracts can be used
to close (or contact) the sealing member and receiving member;
however, some other biasing force must be used when the sealing
member and receiving member are opened (or separated). A spring
biasing force can generally be used as this biasing force; however,
gravity can also be used as a biasing force.
[0015] Furthermore, the rate at which the length of the rubber
tubes contracts is large while the pressure difference between the
pressure inside the tubes and the pressure of the supplied
compressed air is large and decreases as this pressure difference
decreases (i.e., in the final stage of pressurization).
Accordingly, by appropriately controlling the pressure of the
compressed air, it is possible to obtain operating characteristics
in which the opening-and-closing speed of the sealing member and
receiving member is increased, and this speed is decreased at the
instant of closing. Furthermore, since the timing of the supply and
discharge of compressed air to and from the rubber tubes can be
adjusted independently of the driving source of the bag-making
machine or bag-filling packaging machine, the sealing time can be
maintained at a constant time even when the operating speed is
altered in accordance with changes in the production rate of the
bag-making machine or bag-filling packaging machine.
[0016] Tubes marketed under the commercial name of "Rubber Muscle"
by Festo K. K. can be used as the above-described rubber tubes.
[0017] For example, particularly in cases where the above-described
sealing apparatus is applied to a bag-making machine, the sealing
apparatus takes the following configuration: the sealing apparatus
includes a pair of plates which are disposed parallel to each other
so as to be separated by a specified distance, can approach each
other in relative terms from these positions, and are constantly
urged in the direction that separates these plates; a sealing
member and a receiving member which are attached to the pair of
plates so that these members face each other; a plurality of guide
shafts which are disposed perpendicular to the pair of plates and
guide a relative approach and separation of the plates; and a
driving means which closes (or contacts) the sealing member and the
receiving member by way of causing the pair of plates to approach
each other; and in this sealing apparatus, the driving means
comprises a plurality of rubber tubes which expand in the radial
direction and contract in length thereof when compressed air is
supplied thereto and which recover to their original states when
the compressed air is discharged; and further the rubber tubes are
connected to the pair of plates so that the pair of plates approach
each other when the rubber tubes contract in length.
[0018] In the above-described sealing apparatus, both of the pair
of plates can be movable, or one plate can be fixed while the other
plate is movable. In the latter case, for example, the sealing
apparatus can adopt the following configuration: the sealing
apparatus includes a fixed plate; a movable plate which is disposed
parallel to the fixed plate so as to be separated from the fixed
plate by a specified distance, can approach the fixed plate from
this position, and is constantly urged in the direction that
separates this movable plate from the fixed plate; a sealing member
and a receiving member which are attached to the fixed and movable
plates so that these members face each other; a plurality of guide
shafts which are disposed perpendicular to the movable plate and
guide the movement of the movable plate; and a driving means which
closes (or contacts) the sealing member and the receiving member by
way of causing the movable plate to approach the fixed plate; and
in this the sealing apparatus, the driving means comprises a
plurality of rubber tubes which expand in the radial direction and
contract in length thereof when compressed air is supplied thereto
and recovers to their original states when the compressed air is
discharged, one end of each of the rubber tubes is connected to the
movable plate side while the other end of the rubber tube is
connected to the fixed plate side, and the movable plate is caused
to approach the fixed plate when the rubber tubes contract in
length.
[0019] In regard to the above sealing member and receiving member
that constitute the sealing means in the present invention, the
member that mainly performs the sealing action is the sealing
member, and the other member is the receiving member. Accordingly,
in the case of an impulse sealing system, the heater block side is
the sealing member, and the receiving block side is the receiving
member. In the case of an ultrasonic sealing system, the horn side
is the sealing member, and the anvil side is the receiving member.
Furthermore, in the case of a heat sealing system, if the actions
of both heating plates are the same, there is no actual advantage
to be gained from distinguishing between the sealing member and the
receiving member; accordingly, either member can be called the
sealing member or receiving member. However, for example, in cases
where the surface of one of the heating plates is covered by a
heat-resistant elastic material such as a silicone rubber or the
like so that the surface temperature of this heating plate is set
at a lower temperature than that of the other heating plate, then
this first heating plate side is the receiving member. In such
cases, it is desirable that the sealing member (high-temperature
side) be attached to the movable plate and the receiving member
(low-temperature side) be attached to the fixed plate. The reasons
for this will become clear from the description below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a schematic perspective view of a bag-making and
packaging machine in which a bag-making apparatus using the sealing
apparatus of the present invention and a bag-filling packaging
machine are installed together;
[0021] FIG. 2 is a sectional front view of the first sealing
apparatus of the present invention;
[0022] FIG. 3 is a sectional left-side view thereof; and
[0023] FIG. 4 is a sectional left-side view of the second sealing
apparatus of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0024] The sealing apparatus of the present invention will be
concretely described below with reference to FIGS. 1 through 4.
[0025] FIG. 1 is a schematic diagram of a bag-making and packaging
machine in which a bag-making machine 1 and a bag-filling packaging
machine 2 are installed together. The bag-making machine 1 is a
machine that continuously unrolls a film 3 that is rolled up in the
form of a roll, and forms this film into self-standing bags (gusset
bags). This bag-making machine 1 comprises, among others, a
plurality of guide rollers 4, a gatefolding apparatus 5 (forming
roller 5a, forming plate 5b and gatefolding plate 5c), a feed
roller 6 (continuously rotating), a dancer roller 7, a first
sealing apparatus 8, a second sealing apparatus 9, a cooling
apparatus 11, a notch cutter 12, a feed roller 13 (intermittently
rotating), and a side cutter 14.
[0026] In this bag-making machine 1, the film 3 is continuously fed
out and is folded in two by the forming roller 5a and forming plate
5b of the gatefolding apparatus 5. At the same time, a gatefold is
formed in the bottom by the gatefolding plate 5c. The film 3 that
is intermittently fed out via the dancer roller 7 is sealed twice
in places corresponding to both side portions and the bottom of the
bag by the first sealing apparatus 8 and second sealing apparatus
9; then, the sealed portions are cooled by the cooling apparatus
11, circular-arc-form cuts are formed in places correspond to both
of the upper-end corners of the bag by the notch cutter 12, and the
film is separated by cutting into individual bags by the side
cutter 14.
[0027] The basic construction of the above-described bag-making
machine 1 is generally known as is described in, for example,
Japanese Patent Application Laid-Open (Kokai) No. 2002-36392.
[0028] The bags W manufactured by the bag-making machine 1 are
suction-chucked and lifted by the suction plates 15a of a bag
supplying apparatus; then, the bag mouths are gripped by gripping
members 15b, and the bags are supplied to the grippers 17 of the
packaging apparatus 2.
[0029] The packaging apparatus 2 is an intermittently rotating
table type packaging apparatus which is itself generally known (for
example, see the above-described Japanese Patent Application
Laid-Open (Kokai) No. 2002-36392). The packaging apparatus 2 is
arranged so that bags W are received from the bag supplying
apparatus in a stopping position I, and both edge portions of the
bags W are gripped by the grippers 17, after which packaging
operations on the bags W are successively performed while the table
intermittently rotates.
[0030] More specifically, printing is performed on the bag surfaces
by a printer 18 during the movement of the bags W from the stopping
position I to a stopping position II, the bag mouths are opened by
suction plates 19a and air nozzles 19b in a stopping position III,
the bags can be filled with solid matter via hoppers 21 in a
stopping position IV, the bags can be filled with liquid matter via
nozzles 22 in a stopping position V, steam is injected into the
interiors of the bags from steam nozzles 23 in a stopping position
VI, so that gas replacement is performed in the interiors of the
bags, the bag mouths are sealed by a first sealing heater 24 in a
stopping position VII, the bag mouths are again sealed by a second
sealing heater 25 in a stopping position VIII, the sealed portions
are cooled by cooling bars 26 in a stopping position IX, and the
grippers 17 are opened in a stopping position X, so that the filled
and sealed bags W are caused to drop onto a discharge conveyor
27.
[0031] The first sealing apparatus 8 and second sealing apparatus 9
of the bag-making machine 1 are the sealing apparatus of the
present invention. First, the first sealing apparatus 8 will be
described with reference to FIGS. 2 and 3.
[0032] The first sealing apparatus 8 comprises a fixed plate 31
which is horizontally disposed above, a movable plate 32 which is
horizontally disposed beneath the fixed plate 31, a sealing member
33 (hereafter referred to as the "heating plate 33") which is
attached to the movable plate 32 so that this heating plate 33
faces upward, a receiving member 34 (hereafter referred to as the
"heating plate 34") which is attached to the fixed plate 31 so that
this heating plate 34 faces downward, two guide shafts 35 which are
disposed in a vertical attitude, and which guide the movement of
the movable plate 32, and two rubber tubes 36 whose upper ends are
connected to the fixed plate 31, and whose lower ends are connected
to the movable plate 32.
[0033] The lower ends of the guide shafts 35 are fastened to a
horizontally disposed lower plate 37, and the upper ends of these
guide shafts 35 are fastened to the fixed plate 31. Slide members
38 are fastened to the undersurface of the lower plate 37; these
slide members 38 are fit over slide rails 41 that are disposed
along the feeding direction of the film 3 on a machine base 39 so
that these slide members 38 are free to slide. The position of the
first sealing apparatus 8 can be adjusted by means of the slide
members 38 and slide rails 41.
[0034] Bearing holders 42 are fastened to the movable plate 32 at
points located in the vicinity of both ends of the movable plate
32. Slide bearings 43 disposed inside these bearing holders 42 fit
around the circumferences of the guide shafts 35. As a result of
this structure, the movable plate 32 can approach and separate from
the fixed plate 31 while maintaining a horizontal attitude.
Furthermore, recovery compression springs 44 which are used to
cause the movable plate 32 to separate from the fixed plate 31 are
attached between the fixed plate 31 and the bearing holders 42.
[0035] Upper-side tube holding members 47 which have air supply and
discharge holes 45 formed inside are fastened to the upper ends of
the rubber tubes 36. Furthermore, shaft supporting blocks 49 are
fastened to the upper surface of the fixed plate 31, and supporting
shafts 51 are fastened to these shaft supporting blocks 49. The
upper-side tube holding members 47 are fit over the supporting
shafts 51 so that these tube holding members 47 are free to pivot.
Furthermore, lower-side tube holding members 48 which have air
supply and discharge holes 46 formed inside are fastened to the
lower ends of the rubber tubes 36; and holding holes 32a which have
the shape of a truncated circular cone are formed by the movable
plate 32 and holding blocks 52 that are fastened to the outside of
the movable plate 32. The upper end portions 48a of the truncated
circular cone shapes of the lower-side tube holding members 48 are
fit into the holding holes 32a, and step parts 48b on the
lower-side tube holding members 48 engage with the outer
circumferential parts on undersurface sides of the holding holes
32a.
[0036] The above-described air supply and discharge holes 45 and 46
communicate with a pressurization and discharge means (not shown)
that includes a switching valve, regulator and compressor; and the
opening and closing of the switching valve is controlled by a
control device (not shown).
[0037] A heating plate attachment block 53 is fastened to the
surface of the movable plate 32, a heating plate attachment member
54 is fastened to this heating plate attachment block 53, and a
metal heating plate 33 is fastened to the heating plate attachment
member 54. A protruding portion (sealing portion) 33a, which is
used to seal locations corresponding to both side portions and the
bottom of the bags, is formed on the surface of the heating plate
33. Heater attachment holes 33b are formed inside the heating plate
33, and heater rods 56 are inserted into these holes so that the
heating plate 33 is heated.
[0038] A heating plate attachment block 58 is attached to the tip
ends of sealing initial stage pressure setting bolts 57 on the
fixed plate 31 side; a heating plate attachment member 59 is
fastened to this heating plate attachment block 58, and a heating
plate 34 is fastened to the heating plate attachment member 59. The
heating plate 34 includes a metal base portion 34a (with the same
material and structure as those of the heating plate 33) and a
silicone rubber plate 34b that covers this metal base portion 34a.
The surface of this silicone rubber plate 34b is flat. Furthermore,
heater attachment holes 34c are formed in the base portion 34a of
the heating plate 34, and heater rods 62 are inserted into these
holes, so that the heating plate 34 is heated. The surface
temperature of the heating plate 34 is set at a lower temperature
than the surface temperature of the heating plate 33.
[0039] The silicone rubber plate 34b that covers the surface of the
heating plate 34 has the action of evening out the contact between
the protruding portion 33a of the heating plate 33 and the heating
plate 34 when the film 3 is held between this silicone rubber plate
34b and the metal heating plate 33.
[0040] Spring receiving recessed portions 53a and 37a are
respectively formed in the undersurface side of the heating plate
attachment block 53 and the upper surface side of the lower plate
37, and a compression spring 63 is disposed in these recessed
portions 53a and 37a via a through-hole 32b formed in the movable
plate 32. This compression spring 63 acts in conjunction with the
recovery compression springs 44 to suppress vibration of the
movable plate 32 when the movable plate 32 is lowered.
[0041] Final sealing pressure adjustment hollow bolts 64 are
screw-engaged in screw holes formed in the fixed plate 31 and
protrude downward. The sealing initial pressure setting bolts 57
are screw-engaged with the internal screws of these final sealing
pressure adjustment hollow bolts 64 and protrude further downward.
Lock nuts 65 are screw-engaged with the final sealing pressure
adjustment hollow bolts 64, and lock nuts 66 are screw-engaged with
the sealing initial pressure setting bolts 57, above the fixed
plate 31. The heating plate attachment block 58 is engaged with
heads 57a on the lower ends of the sealing initial pressure setting
bolts 57, and compression springs 69 are mounted between the tip
ends of the final sealing pressure adjustment hollow bolts 64 and
the upper surface of the heating plate attachment block 58 with
washers 67 and 68 interposed. The final sealing pressure adjustment
hollow bolts 64 also act to adjust the degree of parallel
orientation of the facing sealing surfaces of the two heating
plates 33 and 34.
[0042] The order of adjustment is performed as follows: first, the
lock nuts 66 are loosened, and the sealing initial pressure setting
bolts 57 are rotated so that the compression springs 69 are
compressed, thus setting the force that acts when the compression
springs 69 begin to be compressed during sealing, i.e., the
pressure in the initial stage of sealing. Then, the lock nuts 66
are tightened. Next, the lock nuts 65 are loosened, and the final
sealing pressure adjustment hollow bolts 64 are rotated so that the
heating plate 34 is moved upward or downward, thus setting the
final amount of compression of the compression springs 69, i.e.,
the final sealing pressure. Then, if necessary, one of the final
sealing pressure adjustment hollow bolts 64 is slightly rotated so
that the inclination of the heating plate 34 is corrected, thus
placing the facing sealing surfaces of the two heating plates 33
and 34 in a parallel orientation. The lock nuts 65 are then
tightened.
[0043] The rubber tubes 36 used as the driving means for the
movable plate 32 in the first sealing apparatus 8 expand in the
radial direction and contract in length when compressed air is
supplied to the interiors of these rubber tubes, so that the
movable plate 32 is raised and approaches the fixed plate 31. As a
result, the heating plate 33 is moved toward the heating plate 34,
so that these two heating plates 33 and 34 come into contact with
each other to close and thus hold and seal specified locations on
the gatefolded film 3. The rate of contraction of the length of the
rubber tubes 36 is large while the pressure difference between the
pressure inside the tubes and the compressed air is large and
decreases as this pressure difference decreases (i.e., in the final
stage of pressurization). Accordingly, by adjusting the air
pressure, it is possible to obtain operating characteristics which
are such that the speed at which the heating plate 33 and heating
plate 34 close (or contact) is large, and the speed at the instant
of closing is small.
[0044] When the compressed air is discharged from the rubber tubes
36, the rubber tubes 36 themselves return to their original length;
at the same time, the movable plate 32 is lowered by the biasing
force of the recovery compression springs 44. In cases where the
movable plate 32 is located below as in the first sealing apparatus
8, the movable plate 32 can also be lowered by gravity;
accordingly, the recovery compression springs 44 are not
essential.
[0045] Furthermore, in cases where the opening and closing (or the
separating and contacting) action of the heating plate 33 and
heating plate 34 is accomplished by the movement of only one of the
heating plates (33) as in the first sealing apparatus 8, the film 3
is fed near the heating plate 34 on the fixed plate 31 side in
order to prevent upward and downward movement of the film 3
accompanying the movement of the heating plate 33. In the first
sealing apparatus 8, since the heating plate 33 on the movable
plate 32 side is heated to a higher temperature, the film 3 is fed
through a position that is separated from this heating plate 33
that is heated to a higher temperature. As result, heating caused
by heat radiating from the heating plate 33 is suppressed, so that
wrinkling of the film 3 is prevented. Furthermore, overheating of
the film 3 when the bag-making machine 2 is stopped is
prevented.
[0046] FIG. 4 shows the second sealing apparatus 9.
[0047] In FIG. 4, members labeled with the same numbers as in the
first sealing apparatus 8 are substantially the same as the members
with these numbers in the first sealing apparatus 8.
[0048] The second sealing apparatus 9 differs from the first
sealing apparatus 8 in that the heating plate 33 that has a high
surface temperature is positioned on the upper side, and the
heating plate 34 that has a low surface temperature is positioned
on the lower side. In addition, the following points are the main
points of difference between the second sealing apparatus 9 and the
first sealing apparatus 8: in the second sealing apparatus 9, (1)
the movable plate 32 is disposed above, and the fixed plate 31 is
disposed below, (2) the fixed plate 31 is fastened to the lower
plate 37, (3) the upper ends of the guide shafts 35 are connected
and fastened by an upper plate 71, (4) the members used for sealing
pressure and sealing position adjustment (i.e., the sealing
position adjustment bolts 57, etc.) belong to the movable plate 32
side, and (5) no part corresponding the compression spring 63 is
installed.
[0049] However, the above structures (1) through (4) are merely
alterations that result from the fact that the heating plate 33
with a high surface temperature is positioned on the upper side and
the heating plate 34 with a low surface temperature is positioned
on the lower side, and (5) is not essential even in the first
sealing apparatus.
[0050] The second sealing apparatus 9 is the same as the first
sealing apparatus 8 in that the heating plate 33 with a high
surface temperature is attached on the movable plate 32 side and
the heating plate 34 with a low surface temperature is attached on
the fixed plate 31 side. Furthermore, the second sealing apparatus
9 is also the same as the first sealing apparatus 8 in that the
rubber tubes 36 are connected between the movable plate 32 and
fixed plate 31. However, in the second sealing apparatus 9, the
recovery compression springs 44 are essential.
[0051] In the second sealing apparatus 9 as well, the film 3 is fed
through a position that is distant from the heating plate 33 that
is heated to a higher temperature.
[0052] The respective operations of the first sealing apparatus 8
and second sealing apparatus 9 can be briefly described as
follows:
[0053] (1) In the first sealing apparatus 8, when compressed air is
supplied to the interiors of the rubber tubes 36 from the air
supply and discharge holes 45 and 46 with the two heating plates 33
and 34 in an open (separated) state (see FIGS. 2 and 3), the rubber
tubes 36 contract in length so that the movable plate 32 is raised,
and the heating plate 33 is moved toward the heating plate 34 so
that the two heating plates 33 and 34 come into contact with each
other to close, thus holding and sealing specified locations on the
gatefolded film 3. In this case, since the heating plate 33 on the
high-temperature side is located below, the film 3 is particularly
heated and sealed from below.
[0054] (2) When compressed air inside the rubber tubes 36 is
discharged from the air supply and discharge holes 45 and 46 after
the specified sealing time has elapsed, the rubber tubes 36 extend
in length so that the movable plate 32 is lowered, thus causing the
heating plate 33 to separate from the heating plate 34, so that the
two heating plates 33 and 34 open. Then, the film 3 is fed by 1
pitch.
[0055] (3) The film 3 that is fed into the second sealing apparatus
9 is sealed in the same manner as in the first sealing apparatus 8.
In this case, however, since the heating plate 33 on the
high-temperature side is located above, the film 3 is particularly
heated and sealed from above (in a manner that is the opposite of
the heating and sealing in the first sealing apparatus 8). Thus,
since the same locations on the film 3 are sealed twice from
opposite directions by the first sealing apparatus 8 and second
sealing apparatus 9, sealing defects tend not to occur.
[0056] (4) After the specified sealing time has elapsed, the two
heating plates 33 and 34 are opened (separated) in the same manner
as in the first sealing apparatus 8, and the film 3 is then fed by
one pitch.
[0057] In the above description, one of the pair of plates is
fixed, while the other plate is made movable. However, it is also
possible to design so that both of the plates are moved at the same
time. Furthermore, the above-described sealing apparatus is
especially suitable for use in a bag-making machine; however, the
present invention is also applicable to sealing apparatuses for a
bag-filling packaging machine. In such a case, for example, the
driving source used in the sealing apparatuses described in the
above-described Japanese Utility Model Registration Nos. 2607484
and 2605892 can be replaced with rubber tubes.
[0058] As seen from the above, according to the present invention,
since rubber tubes are used as the driving source of the sealing
apparatus, such operating characteristics are obtained that the
opening-and-closing speed of the sealing member and receiving
member increases, and the speed at the instant of closing slows
down. Accordingly, a drop in performance and decrease in useful
life caused by the wear of the sealing member and receiving member,
and deterioration in the working environment caused by the
generation of impact noise, can be prevented. Furthermore, since
the rubber tubes themselves generate no impact noise, the working
environment does not deteriorate.
[0059] In addition, since the timing of the supply and discharge of
compressed air to and from the rubber tubes is adjusted
independently of the driving source of the bag-making machine or
bag-filling packaging machine, the sealing time is maintained at a
constant time, and a high sealing quality is obtained, even in
cases where the operating speed is altered in accordance with
changes in the production rate of the bag-making machine or
bag-filling packaging machine.
[0060] Furthermore, since the rubber tubes produce the same output
as air cylinders with tubes of a smaller diameter, the size of the
sealing apparatus can be reduced. Moreover, the structure is
simple, it is superior in terms of coast, cleaning characteristics
and maintenance.
* * * * *