METHOD AND DEVICE FOR SEALING GAS IN A GAS COMPARTMENT-EQUIPPED BAG

Abstract

A method and device for sealing gas in a gas compartment-equipped bag, in which pressurized gas discharge outlets are provided in the distal ends of a horn and an anvil of an ultrasonic sealing device, and such horn and anvil used for ultrasonic sealing are also used as gas-discharging nozzles. The distal ends of the horn and the anvil are placed against a cutout of a gas compartment of a bag, a gas is discharged into the gas compartment from the discharge outlets, the films surrounding the cutout are being clamped by the horn and the anvil while gas discharging is in progress, and then the gas compartment is ultrasonically sealed by the horn and the anvil to trap the gas inside.

Claims

1. A method for sealing gas in a bag, the method comprising: intermittently conveying, by a bag conveyance device, a plurality of gas compartment-equipped bags along a predetermined conveyance path to a filling position to be filled and sealed by an ultrasonic filing and sealing device, wherein the gas compartment-equipped bags include a gas compartment and a gas intake opening, and wherein the gas intake opening is formed in films of a gas introduction portion of the gas compartment on both sides of the gas introduction portion; for a particular gas compartment-equipped bag which is stopped at a filling position along the predetermined conveyance path: moving, a horn and an anvil of the ultrasonic filing and sealing device from a retracted position to an extended position, wherein the horn defines a first gas passage having a first inlet configured to be coupled to a pressurized gas supply source and defines a first outlet configured to provide first gas received from the pressurized gas supply source to a particular gas intake opening of the particular gas compartment-equipped bag, and wherein the anvil is disposed opposite the horn and defines a second gas passage having a second inlet configured to be coupled to the pressurized gas supply source and defines a second outlet configured to provide second gas received from the pressurized gas supply source to the particular gas intake opening, wherein the anvil and the horn face each other with the predetermined conveyance path in between; discharging, by the horn and anvil, the first gas and the second gas into a particular gas compartment of the particular gas compartment-equipped bag via the particular gas intake opening of the particular gas compartment-equipped bag; and providing, by an ultrasonic vibration generator coupled to the horn, ultrasonic vibrations to the horn to ultrasonically seal films surrounding the particular gas intake opening of the particular gas compartment-equipped bag by the horn and anvil.

2. The method of claim 1, further comprising moving, the horn and the anvil to the retracted position, and wherein intermittently conveying, by the bag conveyance device, the plurality of gas compartment-equipped bags along the predetermined conveyance path to the filling position includes moving the particular gas compartment-equipped bag away from the filling position after the particular gas compartment-equipped bag is filled and sealed.

3. The method of claim 2, wherein intermittently conveying, by the bag conveyance device, the plurality of gas compartment-equipped bags along the predetermined conveyance path to the filling position further includes moving a second particular gas compartment-equipped bag to the filling position, and further comprising: moving, the horn and the anvil of the device from the retracted position to the extended position; discharging, by the horn and anvil, the first gas and the second gas into a second particular gas compartment of the second particular gas compartment-equipped bag via a second particular gas intake opening of the second particular gas compartment-equipped bag; and providing, by the ultrasonic vibration generator coupled to the horn, second ultrasonic vibrations to the horn to ultrasonically seal films surrounding the second particular gas intake opening of the second particular gas compartment-equipped bag by the horn and anvil.

4. The method of claim 1, wherein providing the ultrasonic vibrations to the horn to ultrasonically seals a bag mouth of the particular gas compartment equipped bag and the films surrounding the particular gas intake opening of the particular gas compartment at a same time.

5. The method of claim 1, wherein providing the ultrasonic vibrations to the horn to ultrasonically seals the gas compartment independent of a bag mouth of the particular gas compartment equipped bag.

6. The method of claim 1, wherein the extended position is an intermediary position, and wherein the intermediary position is a gas filling position.

7. The method of claim 1, wherein the extended position is a fully extended position which clamps the particular gas compartment equipped bag.

8. The method of claim 1, wherein a face of the horn and a face of the anvil each have a plurality of grooves arranged in a lattice-like pattern which define a plurality of openings between the horn and the anvil when the horn and the anvil are in a gas filing position, and wherein the first and second gases are provided to an intake opening of the gas compartment-equipped bag via the plurality of openings.

9. The method of claim 8, wherein the plurality of grooves extend to an exterior surface of the face of the horn and the face of the anvil.

10. The method of claim 1, wherein moving, the horn and the anvil includes moving, by an air cylinder, the horn and the anvil.

11. The method of claim 1, wherein moving, the horn and the anvil includes moving, by a servo motor, the horn and the anvil.

12. A method for sealing gas in a bag, the method comprising: intermittently conveying, by a bag conveyance device, a plurality of gas compartment-equipped bags along a predetermined conveyance path to a filling position to be filled and sealed by an ultrasonic filing and sealing device, wherein the gas compartment-equipped bags include a gas compartment and a gas intake opening, and wherein the gas intake opening is formed in films of a gas introduction portion of the gas compartment on both sides of the gas introduction portion; for a particular gas compartment-equipped bag which is stopped at a filling position along the predetermined conveyance path: moving, a horn and an anvil of the ultrasonic filing and sealing device from a retracted position to a partially-extended position, wherein: at the partially-extended position, distal ends of the horn and the anvil are opposite and face each other at a predetermined distance that is greater than a total thickness of the films on both sides of the gas introduction portion, the horn defines a first gas passage having a first inlet configured to be coupled to a pressurized gas supply source and defines a first outlet configured to provide first gas received from the pressurized gas supply source to a particular gas intake opening, and the anvil is disposed opposite the horn and defines a second gas passage having a second inlet configured to be coupled to the pressurized gas supply source and defines a second outlet configured to provide second gas received from the pressurized gas supply source to the particular gas intake opening, and the anvil and the horn face each other with the predetermined conveyance path in between; discharging, by the horn and anvil at the partially-extended position, the first gas and the second gas into a particular gas compartment of the particular gas compartment-equipped bag via a particular gas intake opening of the particular gas compartment-equipped bag, wherein the partially-extended position is set so that the films on both sides of the gas introduction portion are inflated by the discharging of the first and second gases come in contact with the distal ends of the horn and the anvil and an inflated state of the gas introduction portion is restricted to a flat shape; moving, the horn and the anvil from the partially-extended position to an extended position to clamp the films surrounding the particular gas intake opening; and providing, by an ultrasonic vibration generator coupled to the horn, ultrasonic vibrations to the horn to ultrasonically seal films surrounding the particular gas intake opening of the particular gas compartment-equipped bag by the horn and anvil.

13. The method of claim 12, wherein moving, the horn and the anvil, from the partially-extended position to the extended position to clamp the films surrounding the particular gas intake opening includes moving, by a compression spring, the horn and the anvil.

14. The method of claim 12, wherein moving, the horn and the anvil, from the partially-extended position to the extended position to clamp the films surrounding the particular gas intake opening includes moving, by a servo motor, the horn and the anvil.

15. The method of claim 12, wherein moving, the horn and the anvil, from the partially-extended position to the extended position to clamp the films surrounding the particular gas intake opening includes moving, by an air cylinder, the horn and the anvil.

16. The method of claim 15, wherein discharging, by the horn and anvil, the first gas and the second gas into the particular gas compartment includes providing, by a pressurized gas supply source separate from the air cylinder, the first gas and the second gas to the horn and the anvil.

17. A method for sealing gas in a bag, the method comprising: intermittently conveying, by a bag conveyance device, a plurality of gas compartment-equipped bags along a predetermined conveyance path to a filling position to be filled and sealed by an ultrasonic filing and sealing device, wherein the gas compartment-equipped bags include a gas compartment and a gas intake opening, and wherein the gas intake opening is formed in films of a gas introduction portion of the gas compartment on both sides of the gas introduction portion; for a particular gas compartment-equipped bag which is stopped at a filling position along the predetermined conveyance path: moving, a horn and an anvil of the ultrasonic filing and sealing device from a retracted position to an extended position, wherein: at the extended position, distal ends of the horn and the anvil are opposite and face each other clamping the films surrounding a particular gas intake opening of the particular gas compartment-equipped bag at a specific biasing force, the horn defines a first gas passage having a first inlet configured to be coupled to a pressurized gas supply source and defines a first outlet configured to provide first gas received from the pressurized gas supply source to the particular gas intake opening, and the anvil is disposed opposite the horn and defines a second gas passage having a second inlet configured to be coupled to the pressurized gas supply source and defines a second outlet configured to provide second gas received from the pressurized gas supply source to the particular gas intake opening, and the anvil and the horn face each other with the predetermined conveyance path in between; discharging, by the horn and anvil at the extended position, the first gas and the second gas into a particular gas compartment of the particular gas compartment-equipped bag via the particular gas intake opening of the particular gas compartment-equipped bag, wherein a pressure of the first and second gases discharged from the first and second outlets causes the horn and the anvil to retract from the extended position to a partially-extended positon against the specific biasing force, at the partially-extended positon a distance between the distal ends of the horn and the anvil is widened to a predetermined distance that is greater than a total thickness of the films on both sides of the gas introduction portion, so that the films on both sides of the gas introduction portion inflated by the discharging of the first and second gases come in contact with the distal ends of the horn and the anvil and an inflated state of the gas introduction portion is restricted to a flat shape; moving, the horn and the anvil from the partially-extended position to an extended position to clamp the films surrounding the particular gas intake opening; and providing, by an ultrasonic vibration generator coupled to the horn, ultrasonic vibrations to the horn to ultrasonically seal films surrounding the particular gas intake opening of the particular gas compartment-equipped bag by the horn and anvil.

18. The method of claim 17, wherein the ultrasonic vibration generator is a lateral, torsional, or longitudinal vibrator.

19. The method of claim 17, wherein the bag conveyance device comprises a plurality of pairs of bag conveyance grippers, each pair of bag conveyance grippers configured to grip both side edges of each of the bags vertically and move the bags intermittently.

20. The method of claim 17, wherein the bag conveyance device comprises a plurality of pairs of bag conveyance grippers, each pair of bag conveyance grippers are oriented across the gas compartment horizontally to grip a sealed portion of the bags and move the bags intermittently.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0046] FIG. 1 is a simplified perspective view of a rotary packaging apparatus that includes the gas sealing device according to the present invention.

[0047] FIG. 2 is a side view of the ultrasonic sealing device according to the present invention.

[0048] FIGS. 3A to 3D are side views illustrating the order of steps taken in the gas sealing method according to the present invention.

[0049] FIGS. 4A and 4B are front views illustrating the order of steps taken in the gas sealing method of the present invention.

[0050] FIGS. 5A and 5B are front views illustrating the order of the next steps taken in the gas sealing method of the present invention.

[0051] FIGS. 6A to 6C are enlarged partial views illustrating the gas sealing method of the present invention.

[0052] FIGS. 7A to 7E are side views illustrating the order of steps taken in another manner of the gas sealing method according to the present invention.

[0053] FIGS. 8A and 8B are cross-sectional views of the horn and the anvil when the films surrounding the cutout formed in the gas introduction portion of the gas compartment of a bag are clamped by the horn and the anvil in the gas sealing method shown in FIG. 7, with FIG. 8A being the cross section view representing the state before ultrasonic vibration energy is supplied to the horn, and FIG. 8B representing the state after this supply has started.

[0054] FIGS. 9A to 9C are side views illustrating the order of steps taken in still another manner of the gas sealing method according to the present invention.

[0055] FIG. 10A is a front view of the horn and the anvil used in the gas sealing method shown in FIG. 9, and FIG. 10B is a detailed side view thereof.

[0056] FIG. 11 is a cross section of the horn and the anvil when the films surrounding the cutout formed in the gas introduction portion of the gas compartment are clamped by the horn and the anvil in the gas sealing method shown in FIG. 9.

[0057] FIG. 12A is a detailed cross sectional view showing before gas discharging in a gas sealing method of related art, and FIG. 12B is a detailed cross sectional view thereof during gas discharging.

[0058] FIG. 13A is a detailed cross sectional view during clamping with blocking grippers in the gas sealing method of related art, and FIG. 13B is a detailed cross sectional view thereof after clamping.

DETAILED DESCRIPTION

[0059] Embodiments encompassed by the gas sealing method and device according to the present invention will be described below with reference to FIGS. 1 to 11.

[0060] FIGS. 4A and 4B show a gas compartment-equipped bag 11 which is a bag equipped with a gas compartment formed in a sealed portion of a side edge of the bag (hereinafter referred to simply as the “bag 11”) for which the gas sealing method and device of the present invention is used.

[0061] The bag 11 is a bottom gusset type of self-standing bag. The bag 11 is composed of films on both the front and back sides, and a folded-over bottom film. In the upper region X of the bag 11, the front and back films are bonded together at the side edges, forming sealed portions 12 and 13. The front and back films are not bonded at the upper edge, which becomes the open bag mouth 14. In the lower region Y of the bag 11, the front and back films are bonded together at the side edges with the bottom film sandwiched in between, and the bottom film itself is also bonded at its folded-over inner side. In the middle part, the front and back films are bonded to the bottom film (the bottom film is not bonded to itself), forming a sealed portion 15. The sealed portions 12, 13, and 15 are indicated with hatching lines in FIGS. 4A and 4B.

[0062] The front and back films are not bonded together in part of the sealed portion 12, forming an unbonded portion 16 (or gas compartment 16).

[0063] The gas compartment 16 is where no pressing or sealing is applied in the heat-sealing of the front and back films of the bag (see 17 and 18 in FIG. 6B), and it has a closed contour that extends in a slender shape downward from near the bag mouth 14 (the upper end of the sealed portion 12). In addition, near that upper end, a cross-shaped cutout (or a gas intake opening) 19 that communicates between the outside of the bag and the inside of the gas compartment 16 is formed in the front and back films. The gas compartment 16 comprises a narrow portion (or neck portion) 16b formed over a specific length from a circular gas introduction portion 16a, in the center of which the cutout 19 is formed, and a wider main portion 16c formed under this neck portion 16b.

[0064] FIG. 1 shows a rotary packaging apparatus in which the gas sealing device according to the present invention is included.

[0065] The rotary packaging apparatus shown in FIG. 1 is similar to the rotary packaging apparatus shown in FIG. 5 of Japanese Patent No. 4683899. The rotary packaging apparatus of FIG. 1 includes a bag conveyance device in which a plurality of pairs of left and right bag conveyance grippers 21 and 22 are provide, equidistantly spaced, around an intermittently rotating table. In this bag conveyance device, the bag conveyance grippers 21 and 22 clamp the side edges (the sealed portions 12 and 13) of each of the supplied bags 11 and intermittently convey the hanging bags along a circular conveyance path. At the various stop positions where the bag conveyance grippers 21 and 22 make stops (stop positions I to VIII), after the bags 11 are supplied to the bag conveyance grippers 21 and 22, various packaging steps such as opening up the bag mouth, filling the bag with its contents, and sealing the bag mouth are successively performed on the bags 11 clamped by the bag conveyance grippers 21 and 22, and these bags are also subjected to the gas sealing method of the present invention that includes a step of discharging a gas in the gas compartment 16 and a step of sealing the gas compartment 16.

[0066] The bag conveyance grippers 21 and 22 each consist of a pair of grip pads, with the gripper 21 clamping the neck portion 16b of the gas compartment 16 so that it goes across it horizontally. As shown in FIG. 4A, a shallow groove 24 running in the up and down direction is formed on the inside (the clamping face) of one of the grip pads 23 of the gripper 21; and when the grippers 21 grips the sealed portion 12, the groove 24 superposes the neck portion 16b.

[0067] In the rotary packaging apparatus of FIG. 1, a conveyor magazine type of bag feeder 25 is disposed at the stop position I of the conveyance path, a printer (only a head 26 thereof is shown) is disposed at the stop position II, an opening device (only a pair of suction cups 27 and an opening head 28 thereof are shown) is disposed at the stop position III, a filling device (only a nozzle 29 thereof is shown) is disposed at the stop position IV, the ultrasonic sealing device according to the present invention (only a horn 31 and an anvil 32 thereof are shown) is disposed at the stop position V, a first sealing device that seals the bag mouth (only a pair of hot plates 33 thereof is shown) is disposed at the stop position VI, a second sealing device that seals the bag mouth (only a pair of hot plates 34 thereof is shown) is disposed at the stop position VII, and a cooling device (only a pair of cooling plates 35 thereof is shown) is disposed at the stop position VIII.

[0068] In the above-described rotary packaging apparatus, the bag conveyance device and the ultrasonic sealing device comprises the gas sealing device.

[0069] FIG. 2 shows the ultrasonic sealing device according to the present invention. This ultrasonic sealing device includes the horn 31, the anvil 32, an ultrasonic vibration generator 36 that vibrates the horn 31, and an air cylinder 37 that moves the horn 31 and the anvil 32 back and forth (or move them closer to and away from each other). Attachment members 41 and 42 are fixed to the distal ends of piston rods 38 and 39 of the air cylinder 37, the ultrasonic vibration generator 36 is fixed to the attachment member 41, and the anvil 32 is fixed to the attachment member 42. This ultrasonic sealing device has a cooling means (not shown), and the ultrasonic vibration generator 36, the horn 31, and the anvil 32 are cooled by this cooling means.

[0070] A hole 43 (gas passage) is formed in the horn 31. One end of the hole 43 opens in a side face of the horn 31 and is connected to a pressurized gas supply source 46 via a connector 44, a pipe 45, a shutoff valve (not shown), etc. The other end of the hole 43 opens in the distal end of the horn 31 and serves as a discharge outlet 47 for the pressurized gas. A hole 48 (gas passage) is formed in the anvil 32. One end of the hole 48 opens in the rear end of the anvil 32 and is connected to the pressurized gas supply source 46 via a connector 49 and a pipe 51. The other end of the hole 48 opens in the distal end of the anvil 32 and serves as a discharge outlet 52 for the pressurized gas.

[0071] With the structures above, the horn 31 and the anvil 32 also serve as gas-discharging nozzles (in addition to a ultrasonic sealing means).

[0072] The horn 31 and the anvil 32 are disposed opposite and face each other with the conveyance path of the bag 11 in between, and they are moved forward (toward the conveyance path) or backward (away from the conveyance path) between their extended positions and the retracted positions, respectively, symmetrically and perpendicular to the bag 11, by the air cylinder 37. When the horn 31 and the anvil 32 are both in the retracted positions (see FIG. 3A), the horn 31 and the anvil 32 are farthest away from the conveyance path (and from each other), and this avoids interference with the bags 11 being conveyed along the conveyance path. When the horn 31 and the anvil 32 have come to their extended positions (see FIG. 3C), the horn 31 and the anvil 32 are closest to the conveyance path (and to each other), and the horn 31 and the anvil 32 clamp the bag 11 with their distal ends. At this time (when the horn 31 and the anvil 32 are at their extended positions and closest to the conveyance path and to each other), the distance between the distal ends of the horn 31 and the anvil 32 is equal to the thickness of the films on both sides of the gas introduction portion 16a of the gas compartment 16.

[0073] The air cylinder 37 is a three-position type, allowing the horn 31 and the anvil 32 to stop at an intermediate position thereof between the retracted positions and the extended positions. The intermediate position (hereinafter also referred to as a “discharging position”) is a position that is extremely close to the extended position (see FIG. 3B and FIGS. 6A to 6C) of each of the horn and anvil, and a gas is discharged into the gas compartment 16 by the horn 31 and the anvil 32 that are stopped at their intermediate positions.

[0074] An example of a packaging method (including a gas sealing method) employed in the rotary packaging apparatus shown in FIG. 1 will be described with reference to FIGS. 1 to 6C.

[0075] (1) At the stop position I (bag feeding position), bags 11 are supplied from the conveyor magazine type of bag feeder 25 to the grippers 21 and 22, and the grippers 21 and 22 grip the sealed portions 12 and 13 at predetermined positions on both the front and back sides. The gas compartment 16 at this point is gripped at its neck portion 16b by the gripper 21. This state is shown in FIG. 4A.

[0076] (2) At the stop position II (printing position), the bag face is printed by a printer.

[0077] (3) At the stop position III (opening position), the bag is opened by an opening device. More specifically, the pair of suction cups 27 of the opening device are moved back and forth toward the bag 11, and when moved forward they grab the films on both sides of the bag 11, and then when moved backward they open the bag mouth 14. The opening head 28 moves up and down above the bag 11; and when it has descended, its lower end moves through the bag mouth 14 into the bag and discharges gas into the bag.

[0078] (4) At the stop position IV (content filling position), the opened bag is filled with, for instance, liquid contents by a filling device (see the contents 53 in FIG. 4B). The nozzle 29 of the filling device is movable up and down above the bag 11; and when it has descended, it goes through the bag mouth 14 into the bag and fills the bag with liquid.

[0079] (5) At the stop position V (gas discharging and sealing position), the ultrasonic sealing device shown in FIG. 2 is disposed near the conveyance path for the bag 11, and a gas discharging step that discharge a gas into the gas compartment 16 of the bag 11 and a sealing step that seals the films surrounding the cutout 19 are performed.

[0080] When the bag 11 is stopped at the stop position V, as shown in FIG. 3A, the horn 31 and the anvil 32 are at their retracted positions. The air cylinder 37 is then actuated and, as shown in FIGS. 3B and 6A, the horn 31 and the anvil 32 are moved forward and stop at positions (the discharging positions) just short of their extended positions. The distal ends of the horn 31 and the anvil 32 at this point are opposite and face each other and at a distance D that is slightly greater than the thickness of the films on both sides of the gas introduction portion 16a. As seen from FIG. 4B, the inside diameter (the diameter) of the discharge outlets 47 and 52 of the horn 31 and the anvil 32, respectively, is set to be less than the diameter of the gas introduction portion 16a of the gas compartment 16. Consequently, the gas discharged from the discharge outlets 47 and 52 collects in the gas introduction portion 16a, allowing the gas to be discharged into the gas compartment 16 more efficiently. If the gas introduction portion 16a is not circular, the inside diameter of the discharge outlets 47 and 52 can be set smaller than the width (which is in the bag width direction) of the gas introduction portion.

[0081] The discharging of the pressurized gas from the discharge outlets 47 and 52 is started either simultaneously with the stopping of the horn 31 and the anvil 32 at the discharging position or at a suitable point before or after that. When gas is discharged from the discharge outlets 47 and 52 through the cutout 19 and into the gas introduction portion 16a of the gas compartment 16, the films 17 and 18 on both sides of the gas introduction portion 16a inflate and, as shown in FIG. 6B, the films come in close contact with the flat distal end faces 54 and 55 of the horn 31 and the anvil 32, respectively (see FIG. 2). Therefore, the gas introduction portion 16a cannot inflate any further, and its inflation state is restricted to a thin, flat shape when viewed from above. The above-described distance D is set so that the inflation state of the gas introduction portion 16a becomes flat in shape.

[0082] The pressurized gas that enters the gas introduction portion 16a spreads open the front and back films of the neck portion 16b clamped by the gripper 21 by an amount equal to the depth of the groove 24, flows through the gap created between the films into the main portion 16c, and inflates the main portion 16c. A state in which the main portion 16c has inflated is shown in FIG. 6C.

[0083] The air cylinder 37 is again actuated at a specific timing after the horn 31 and the anvil 32 stop at their discharging positions, so that the horn 31 and the anvil 32 are moved forward and immediately reach their extended positions and, as shown in FIG. 3C, the distal ends of the horn 31 and the anvil 32 clamp the gas introduction portion 16a (the films surrounding the cutout 19) of the gas compartment 16. At this point, the inflation state of the gas introduction portion 16a is a thin, flat shape, so that no wrinkles (see winkles 8 of FIG. 13) are produced, and the gas introduction portion 16a can be completely flattened out.

[0084] Next, ultrasonic vibration is generated from the ultrasonic vibration generator 36, and vibration energy is supplied to the horn 31. As shown in FIG. 5A, a ring-shaped ultrasonically sealed portion 56 (the ring-shaped area that is hatched) is formed coinciding with the shape of the area (clamped part) clamped by the horn 31 and the anvil 32 (reflecting the shape of the distal end face 54 of the horn 31). Although all or most of the cutout 19 of the gas introduction portion 16a is not sealed, the films surrounding the cutout 19 are sealed, so that the gas inside the gas compartment 16 is sealed (or trapped) inside, without leaking out through the cutout 19.

[0085] When the ultrasonic sealing is completed (when the generation of ultrasonic waves ends), there is no more frictional heat generated by ultrasonic vibration, and as a result the ultrasonically sealed portion 56 clamped by the distal ends of the horn 31 and the anvil 32 is immediately cooled by the horn 31 and the anvil 32. After the ultrasonic sealing ends, the air cylinder 37 is operated in reverse at a suitable timing, thus retracting the horn 31 and the anvil 32 until they stop at their retracted positions as shown in FIG. 3D.

[0086] The discharging of the pressurized gas from the discharge outlets 47 and 52 of the horn 31 and the anvil 32, respectively, is preferably continued until just before the horn 31 and the anvil 32 reach their extended positions and clamp the gas introduction portion 16a. Also, the discharging of the pressurized gas is preferably stopped at a suitable timing before the horn 31 and the anvil 32 start to retract.

[0087] (6) At the stop position VI (first sealing position), the pair of hot plates 33 clamp the bag mouth 14 and heat-seal it, fowling a sealed portion 57 (see FIG. 5B). There is no need to clamp the site of the cutout 19 with the hot plates 33 at this point, since the sealing of the gas compartment 16 has already been completed.

[0088] (7) At the stop position VII (second sealing position), the pair of hot plates 34 again clamp the sealed portion 57 for a second round of heat sealing.

[0089] (8) At the stop position VIII (sealed portion cooling and discharge step), the pair of cooling plates 35 clamp and cool the sealed portion 57. Then, the grippers 21 and 22 are opened during cooling, then the cooling plates 35 are also opened, allowing the bag 11 (finished bag) to drop and be discharged through a chute 50 to outside the device.

[0090] In the first embodiment above, the air cylinder 37 of the ultrasonic sealing device is a three-position type, and the horn 31 and the anvil 32 are stopped at three positions: the extended positions, the discharging positions, and the retracted positions. However, the air cylinder 37 can be a two-position type, so that the thrust that moves the horn 31 and the anvil 32 forward (which is the air pressure used) can be switched. With this two-position type cylinder as well, the discharging of the gas into the gas compartment 16 and the sealing of the gas compartment 16 (the gas introduction portion 16a) can be performed in the same manner as in the first embodiment above.

[0091] In this second embodiment that employs a two-position type cylinder, the discharging of the gas into the gas compartment 16 and the sealing of the gas compartment 16 are performed as follows, for example.

[0092] The horn 31 and the anvil 32 are moved forward under the operation of the air cylinder 37 until they reach their extended positions, so that the horn 31 and the anvil 32 clamp, with their distal ends, the gas introduction portion 16a of the gas compartment 16 (or the films surrounding the cutout 19) at a biasing force corresponding to the thrust of the air cylinder (the initial thrust).

[0093] When the horn 31 and the anvil 32 discharge pressurized gas from their discharge outlets 47 and 52, since the discharge outlets 47 and 52 are blocked by the film of the gas introduction portion 16a, the pressure of the gas rises, the horn 31 and the anvil 32 are retracted from their extended positions against the thrust of the air cylinder 37 (the biasing force that clamps the gas introduction portion 16a of the gas compartment 16), and the distance between the distal ends of the horn 31 and the anvil 32 is widened until it is slightly greater than the thickness of the films on both sides of the gas introduction portion 16a of the gas compartment 16. This distance may be about the same as the distance D described in the first embodiment of the gas sealing method above. In other words, the initial thrust of the air cylinder 37 is set so that the horn 31 and the anvil 32 are retracted under the pressure of the gas they themselves discharge, and the distance between the distal ends of the retracted horn 31 and anvil 32 is about the same as the above-described distance D.

[0094] The widening of the distance between the distal ends of the horn 31 and the anvil 32 causes the gas to be discharged through the cutout 19 into the gas introduction portion 16a, which inflates the films 17 and 18 on both sides of the gas introduction portion 16a and creates a gap between the films, and the gas flows into the neck portion 16b, and then into the main portion 16c, which inflates the main portion 16c. The films on both sides of the gas introduction portion 16a are brought into close contact with the flat distal end faces 54 and 55 of the horn 31 and the anvil 32 (see FIG. 6B), and the inflation state of the gas introduction portion 16a is restricted to a thin, flat shape.

[0095] The thrust of the air cylinder 37 is switched at a suitable timing (switched to a thrust that is greater than the initial thrust), so that the horn 31 and the anvil 32 are moved forward and again reach their extended positions, and the gas introduction portion 16a of the gas compartment 16 (the films surrounding the cutout 19) is clamped by the horn 31 and the anvil 32. Ultrasonic vibration is then generated from the ultrasonic vibration generator 36, and ultrasonic sealing is performed, forming the ring-shaped ultrasonically sealed portion 56 (see FIG. 5A).

[0096] After the ultrasonic sealing is finished, the air cylinder 37 is operated in reverse at a suitable timing, and the horn 31 and the anvil 32 are retracted and stop at the retracted positions.

[0097] The timing at which the discharging of the pressurized gas from the discharge outlets 47 and 52 is stopped can be the same as that in the first embodiment above.

[0098] In the second embodiment above, when ultrasonic sealing is performed, the thrust of the air cylinder 37 is switched to a higher thrust, so that the horn 31 and the anvil 32 are moved forward again, and the gas introduction portion 16a of the gas compartment 16 is clamped. However, if the discharging of the pressurized gas is halted instead of switching the thrust in that way, the horn 31 and the anvil 32 can be likewise moved forward again so that the gas introduction portion 16a of the gas compartment 16 is clamped thereby.

[0099] If the discharging of the pressurized gas is halted, the thrust of the air cylinder 37 immediately moves the horn 31 and the anvil 32 forward so that they clamp the gas introduction portion 16a, and leakage of the gas form the cutout 19 stops. Also, since the neck portion 16b is formed in the gas compartment 16, and the distance is narrow between the films on both sides of the neck portion 16b (widening only to the depth of the groove 24 of the gripper 21), the leakage of gas inside the main portion 16c does not proceed all at once. Accordingly, the gas can be sealed inside the gas compartment 16 by ultrasonically sealing the gas introduction portion 16a. The pressure of the gas may be also reduced instead of halting the discharging of the pressurized gas.

[0100] In the third embodiment above, the air cylinder 37 is used as the drive source for moving the horn 31 and the anvil 32 back and forth, and the thrust thereof is applied to the biasing force for clamping the gas introduction portion 16a of the gas compartment 16. Nonetheless, a compression spring (see the nozzle 17 and the compression spring 19 of Japanese Patent No. 4683899, for example) can be provided for biasing the horn 31 and the anvil 32 forward, thus applying the resilient force of this compression spring to the biasing force. In this case, the drive source for moving the horn 31 and the anvil 32 back and forth need not to be an air cylinder.

[0101] In this arrangement, the horn 31 and the anvil 32 are moved forward by the resilient force of the compression spring when the discharging of pressurized gas from the horn and the anvil is stopped, or the pressure of the pressurized gas is reduced.

[0102] In the first embodiment described above, the air cylinder 37 of the ultrasonic sealing device is a three-position type; and when the gas is discharged into the gas compartment 16, the horn 31 and the anvil 32 are stopped at their discharging positions, at which point their distal ends are opposite and face each other at a predetermined distance (the distance D, which is slightly greater than the thickness of the films on both sides of the gas introduction portion 16a). In the fifth embodiment below, however, the horn 31 and the anvil 32 are stopped only at the extended positions and the retracted positions, and not at the discharging positions (positions just short of the extended positions). Therefore, the air cylinder 37 can be a two-position type. Also, in this fifth embodiment, longitudinal vibration energy (vibration perpendicular to the welding face) is supplied to the horn 31. The fifth embodiment is described below in specific terms with reference to FIGS. 7A through 8B (and also FIGS. 1 and 2).

[0103] When the bag 11 stops at the stop position V (see FIG. 1), the horn 31 and the anvil 32 are at their retracted positions as shown in FIG. 7A.

[0104] Then, the air cylinder 37 (see FIG. 2) is actuated to move the horn 31 and the anvil 32 forward from their retracted positions, and midway through this movement the discharging of the gas from the discharge outlets 47 and 52 in the distal ends of the horn 31 and the anvil 32 is begun.

[0105] As shown in FIG. 7B, as the horn 31 and the anvil 32 approach their extended positions, gas flows through the cutout 19 into the gas compartment 16, and inflates the gas compartment 16.

[0106] Then, as shown in FIGS. 7C and 8A, the horn 31 and the anvil 32 are moved to reach their extended positions, and their distal end faces 54 and 55 (see FIG. 2) clamp the films surrounding the cutout 19. Although the discharging of gas from the discharge outlets 47 and 52 continues, the flow of gas into the gas compartment 16 stops at this point. The horn 31 and the anvil 32 reach their extended positions from their retracted positions in an extremely short time, during which not enough of the gas is discharged into the gas compartment 16, and the gas compartment 16 is not sufficiently inflated at the point when the horn 31 and the anvil 32 reach their extended positions.

[0107] Next, ultrasonic longitudinal vibration energy is supplied to the horn 31. The horn 31 vibrates (moves back and forth with respect to the anvil 32) at a very small amplitude (from a few dozen to a few hundred microns (.mu.m)) and a high frequency, and ultrasonic sealing is commenced. The vibration direction of the horn 31 is shown by the arrow in FIG. 8B. When the horn 31 has been retracted by the amount of the above-described amplitude and the distance between the horn 31 and the anvil 32 has widened, then the pressure of the gas discharged from the discharge outlets 47 and 52 pushes apart the films on both sides of the clamped part (the site clamped by the distal end faces 54 and 55 of the horn 31 and the anvil 32) and creates a very small gap, and at that instant the gas flows through this gap into the gas compartment 16.

[0108] As time passes, the amount of gas flowing into the gas compartment 16 increases, and the gas compartment 16 inflates accordingly (see FIGS. 7D and 8B), and then the sealant on the inner layer of the films is melted by frictional heat and fills in the gap (at which point the flow of gas into the gas compartment 16 again stops), so that the films on both sides of the clamped part are sealed. The ultrasonic vibration energy is supplied to the horn 31 for only a very short time (no more than 1.0 second, and usually about 0.2 to 0.4 second), and both the discharging of gas into the gas compartment 16 and the ultrasonic sealing of the gas compartment 16 are achieved during that time, and the gas is sealed inside the gas compartment 16. After this ultrasonic sealing, the discharging of gas from the discharge outlets 47 and 52 is stopped. The ultrasonically sealed portion is in the same ring shape as the shape of the distal end face 54 of the horn 31, just like that of the ultrasonically sealed portion 56 shown in FIG. 5A.

[0109] When the supply of vibration energy to the horn 31 is stopped and ultrasonic sealing is finished, no more frictional heat is generated in the ultrasonically sealed portion of the films. As a result, the ultrasonically sealed portion clamped by the distal ends of the horn 31 and the anvil 32 is immediately cooled by the horn 31 and the anvil 32. After the ultrasonic sealing thus ends, the air cylinder 37 is operated in reverse at a suitable timing, thus retracting the horn 31 and the anvil 32 until they stop at the retracted positions as shown in FIG. 7E.

[0110] Because the ultrasonic sealing generally lasts only an extremely short period of time, not much gas flows into the gas compartment 16 during this time. However, as described above, a certain amount of gas, although insufficient, is discharged into the gas compartment 16 before the films surrounding the cutout 19 are clamped by the horn 31 and the anvil 32; accordingly, in total a sufficient amount of gas is discharged into the gas compartment 16, and the gas compartment 16 can be sufficiently inflated.

[0111] With this fifth embodiment, the inflation state of the gas introduction portion 16a at the point when the gas introduction portion 16a is clamped by the horn 31 and the anvil 32 is in a flat shape (not inflated very much). Accordingly, the vertical wrinkles (such as winkles 8 illustrated in FIG. 13A) are prevented from occurring.

[0112] If the duration of the ultrasonic sealing can be extended for a relatively long time, a sufficient amount of gas is discharged into the gas compartment 16, and the gas compartment 16 can be sufficiently inflated during only the ultrasonic sealing period. In this case, the discharging of the gas from the discharge outlets 47 and 52 can be performed in the first half of the period from the start of ultrasonic sealing to the end (until the flow of gas into the gas compartment 16 stops). For example, the discharging of gas can be started to match (be simultaneous with) the timing of the start of ultrasonic sealing and ended before the end of the ultrasonic sealing. However, as described above, since the ultrasonic sealing generally lasts only an extremely short time, it is practical to start the discharging of the gas at a suitable point before the films surrounding the cutout 19 are clamped by the horn 31 and the anvil 32, and leave it to continue until the ultrasonic sealing ends.

[0113] In the fifth embodiment above, the distal end faces 54 and 55 of the horn 31 and the anvil 32 are flat. In the sixth embodiment below, fine grooves are formed in the distal end faces 54 and/or 55 of the horn 31 and/or the anvil 32. The sixth embodiment will be described below in specific terms with reference to FIGS. 9A through 11.

[0114] As shown in FIGS. 10 and 11, fine, lattice-like grooves 58 and 59 whose ends open to the inner periphery (the discharge outlets 47 and 52) and/or the outer periphery of the distal end faces 54 and 55 of the horn 31 and the anvil 32 are formed over the entire surface of the distal end faces 54 and 55 (the groove 58 are on the end surface 54 of the horn 31, and the grooves 59 are on the end surface 55 of the anvil 32). The discharging of the gas into the gas compartment 16 and the ultrasonic sealing of the gas compartment 16 using the horn 31 and the anvil 32 are performed as follows, for example.

[0115] When the bag 11 stops at the stop position V (see FIG. 1), as shown in FIG. 9A, the horn 31 and the anvil 32 are retracted to the retracted positions.

[0116] The air cylinder 37 is actuated (see FIG. 2), and the horn 31 and the anvil 32 are moved forward (or toward each other) from their retracted positions and reach the extended positions and, as shown in FIG. 9B, their distal ends clamp the films surrounding the cutout 19 formed in the gas introduction portion 16a of the gas compartment 16, and then gas is discharged from the discharge outlets 47 and 52 in the distal ends of the horn 31 and the anvil 32, respectively.

[0117] The gas that goes through the cutout 19 into the gas introduction portion 16a pushes apart the films of the gas introduction portion 16a within the grooves 58 and 59, creating numerous small gaps between the films on both sides. The gas flows through these gaps into the neck portion 16b that lies ahead of the gas introduction portion 16a then flows further into the main portion 16c, inflating the gas compartment 16. However, the films surrounding the cutout 19 are not inflated while still clamped by the distal ends of the horn 31 and the anvil 32 and are only pushed apart slightly within the grooves 58 and 59.

[0118] Next, ultrasonic vibration is generated from the ultrasonic vibration generator 36 at a specific timing, and the ultrasonic vibration energy is supplied to the horn 31, and the films on both sides of the site clamped by the distal ends of the horn 31 and the anvil 32 (the area around the cutout 19) are ultrasonically sealed. In this ultrasonic sealing, there are small gaps between the films on both sides on the inside of the grooves 58 and 59; as a result, no frictional heat is generated and the sealant of the inner layer does not melt. Nonetheless, the nearby molten sealant fills in these gaps (at which point the flow of gas into the gas compartment 16 stops), and sealing is performed, including the films inside of the grooves 58 and 59, which seals or traps the gas inside the gas compartment 16. If the vibration energy supplied to the horn 31 is longitudinal vibration energy, the action discussed in the fifth embodiment above (whereby vibration of the horn 31 forms minute gaps between the films on both sides of the clamped part, and the gas flows through these gaps into the gas compartment 16) is also obtained at the same time.

[0119] As seen from FIG. 10, the width w and depth d of the grooves 58 and 59 formed in the distal end faces 54 and 55 of the horn 31 and the anvil 32 are set so that the above-described gaps are formed when gas is discharged into the gas compartment 16, and these gaps are filled in by the surrounding molten sealant during ultrasonic sealing.

[0120] The ultrasonically sealed portion thus produced is in the same ring shape as the shape of the distal end face 54 of the horn 31, just like that of the ultrasonically sealed portion 56 shown in FIG. 5A.

[0121] When the ultrasonic sealing ends (when the generation of ultrasonic waves ends), there is no more frictional heat generated by ultrasonic vibration, and the ultrasonically sealed portion clamped by the distal ends of the horn 31 and the anvil 32 is immediately cooled by the horn 31 and the anvil 32. After the ultrasonic sealing thus ends, the air cylinder 37 is operated in reverse at a suitable timing, which retracts the horn 31 and the anvil 32 until they stop at their retracted positions as shown in FIG. 9C. The discharging of gas from the discharge outlets 47 and 52 can be ended before the ultrasonic sealing ends, as described for the fifth embodiment above; however, it is practical to keep it continue until the ultrasonic sealing ends.

[0122] With this sixth embodiment, the gas compartment 16 that has not yet been inflated is clamped by the horn 31 and the anvil 32, gas is discharged into the gas compartment while it is still being clamped, and ultrasonic sealing is performed in this state. Accordingly, there is no way for the vertical wrinkles 8 illustrated in FIG. 12A to occur.

[0123] Also, in this sixth embodiment, unlike in the fifth embodiment above, the ultrasonic vibration energy supplied to the horn 31 may be some other vibration mode, such as lateral vibration or torsional vibration, rather than longitudinal vibration. This is also applicable to the first to fourth embodiments above.

[0124] In this sixth embodiment, the discharging of gas from the discharge outlets 47 and 52 can be, as in the fifth embodiment, started at a suitable timing before the film surrounding the cutout 19 is clamped by the horn 31 and the anvil 32.

[0125] Although the first to sixth embodiments of the present invention are described above with reference to FIGS. 1 to 11, the present invention can be embodied in different manners as below:

[0126] (1) In the above description, both the horn 31 and the anvil 32 also serve as gas-discharging nozzles in addition to as sealing means. However, when the gas is discharged into the gas compartment 16, only one of these can be used as a nozzle (to discharge gas), with the other being used as a receiver (that does not discharge gas and only receives and holds the gas compartment 16) (see, for instance, the receiver 12 described in Japanese Patent No. 4771785). Also, the gas passage (including discharge outlets) need not to be formed on the horn 31 or the anvil 32 that serves as the receiver.

[0127] When either one of the horn 31 and the anvil 32 is used as the receiver in the structure of the First Embodiment, the one that serves as the receiver is set to be movable forward to its extended position (the position closest to the conveyance path) from the very start of the discharging step, so that it is kept positioned in the extended position during the discharging step and the sealing step. Also, in the Second to Fourth Embodiments above, if the horn 31 or the anvil 32 is used as the receiver, the one that serves as the receiver can be kept positioned in the extended position during the discharging step and the sealing step, without being retracted from the extended position (the position closest to the conveyance path) that is set in the discharging step.

[0128] (2) In the above description, the bag (gas compartment-equipped bag) 11 has the cutout 19 which is formed in the films 17 and 18 on the front and back sides of the gas compartment 16. Nonetheless, a gas compartment-equipped bag in which the cutout 19 is formed in only one of the films can be processed by the present invention. In this case, when the gas is discharged into the gas compartment 16, out of the horn 31 and the anvil 32, the one disposed on the cutout 19 side is used as the nozzle, and the other one is used as the receiver (see (1) above).

[0129] (3) In the above description, the cutout 19 is formed in the upper end of the gas compartment 16; however, the cutout 19 can be formed somewhere else instead, and a hole (or a gas intake opening) can be also formed instead of the cutout 19.

[0130] (4) In the above description, the neck portion 16b is formed in the gas compartment 16. Nonetheless, the entire gas compartment 16 may have the same width as in the gas compartment-equipped bag discussed in Japanese Patent Nos. 4683899 and 4771785.

[0131] (5) In the above description, the gripper 21 that grips the sealed portion 12, in which the gas compartment 16 is formed, grips the sealed portion 12 so that the gripper goes across the gas compartment 16 horizontally. However, the gripper 21 can be formed so as instead to grip only the outside of the gas compartment 16 as in the bag conveyance gripper discussed in Japanese Patent Nos. 4683899 and 4771785.

[0132] (6) In the above description, only the gas compartment 16 is sealed by the ultrasonic sealing device. It, however, can be designed so that the bag mouth 14 is also clamped at the same time by the horn 31 and the anvil 32, so that the gas compartment 16 and the bag mouth 14 are sealed at the same time.

[0133] (7) In the above description, the air cylinder 37 is the drive source for moving the horn 31 and the anvil 32 of the ultrasonic sealing device forward and backward. A servo motor can be used instead as the drive source.

[0134] (8) In the above description, the gas sealing method and device constitutes part of a packaging method and a packaging device; however, the gas sealing method and device of the present invention can instead be configured as an independent gas sealing method or gas sealing device, being separated from the opening of the bag mouth and the filling of the bag with its contents. In this case, a suction cup that grabs the bag 11 at the bag face, a chuck that grasps the bag mouth, or the like can be used instead of the pair of left and right bag conveyance grippers 21 and 22 as the conveyance member for conveying the bag 11.

[0135] (9) In the above description, the gas sealing method and device according to the present invention are applied to a case that gas compartment-equipped bags are intermittently conveyed. The present invention can be also applied to a case that gas compartment-equipped bags are continuously conveyed at a steady rate (see, for instance, Japanese Laid-Open Patent Application 2009-161230). When a gas compartment-equipped bags are continuously conveyed, the ultrasonic sealing device, for instance, follows the movement of the gas compartment-equipped bags, and then returns, follows the next bag, and performs the required processing in the course of such movement.