BAG OPENING APPARATUS AND BAG OPENING METHOD

Abstract

 A bag opening apparatus and a bag opening method capable of efficiently opening a bag body in a short period of time are provided. A bag opening apparatus (10) includes a gap formation unit (11) which bends at least a front wall portion (102), of the front wall portion and a back wall portion (103) that constitute a mouth portion (101) of a bag body (100), so as to form a gap. When a first press drive member (23) presses a first holding unit (25) against the front wall portion, a contact part (31) of the first holding unit is swung against urging force of an urging part (33) of the first holding unit to bend the front wall portion.

Description

TECHNICAL FIELD

[0001] The present invention is related to a bag opening apparatus and a bag opening method.

BACKGROUND ART

[0002] Conventionally, as apparatuses for opening the mouth portion of a bag body, such as a package bag, apparatuses adopting various methods have been proposed. For example, according to a device using a suction cup for opening a bag body, the suction cup is kept in contact with a bag surface over a predetermined time until an appropriate negative pressure is formed between the suction cup and the bag surface, and then, the suction cup is moved together with the bag surface so that the mouth portion is opened.

[0003] On the other hand, Japanese examined utility model (registration) application publication No. 3-22084 discloses an apparatus which opens a flat film tube without using a suction cup. In this apparatus, rollers forming a pair are once moved outward in the width direction in a state of being in contact with a tube surface, and thereafter, the rollers forming a pair are moved inward in the width direction using the elastic force of a spring while the rotation of each of the rollers is restricted. As a result, the tube surface is dragged to the pair of rollers moving inward in the width direction, so that a gap is formed in the mouth portion of the tube.

[0004] Further, Japanese patent application publication No. 2013-82487 discloses an apparatus which opens a package bag made of paper, nonwoven fabric or the like. In this apparatus, a package bag is opened by moving a pair of conveyance claws in a closed state while a part of the package bag is nipped between the closed conveyance claws.

SUMMARY OF INVENTION

Technical Problem

[0005] In an opening device using a suction cup, a period of time for placing the suction cup in a halt state is needed in order to make the suction cup to suck a bag surface as described above. This period of time becomes a bottleneck for speeding up the opening process of a bag body. In particular, when the opening process of a bag body is combined with another process such as a packaging process, the period of time required for the suction of a suction cup can be a major factor impeding improvement of the performance of the whole processing.

[0006] In addition, in the apparatus disclosed in Japanese examined utility model (registration) application publication No. 3-22084, prior to forming a gap in the mouth portion of a tube by moving a pair of rollers inward in the width direction, a preliminary operation which makes the pair of rollers move outward in the width direction is needed. This preliminary operation is also one of the factors hindering the improvement of the processing performance. In particular, when it is necessary to obtain a large gap formed in the mouth portion of a tube as in the case where the tube width is large, it is also necessary to make larger the displacement amount of the tube. In this case, it is necessary to increase the amount of inward movement of the pair of rollers in the width direction; however, for this purpose, it is necessary to increase the amount of outward movement of the pair of rollers in the width direction in the preliminary operation, and thus the time required for the processing is greatly increased. As described above, an apparatus and a method which need to perform the preliminary operation depending on the actual opening operation are not necessarily suitable for high-speed processing.

[0007] Moreover, in the apparatus disclosed in Japanese patent application publication No. 2013-82487, the conveyance claws forming two pairs (that is, four conveyance claws) are alternately arranged in a state where a package bag is positioned therebeteen, and the package bag is bent and folded in accordance with the shape of the conveyance claws. In this case, the package bag is gripped and opened by the conveyance claws in a sharply folded state. Therefore, in a case where a package bag is opened by using the apparatus of Japanese patent application publication No. 2013-82487, depending on the material of the package bag, folding/bending marks remain in the package bag and thus the aesthetic appearance and the quality of the package bag are impaired.

[0008] Furthermore, in the apparatus of Japanese examined utility model (registration) application publication No. 3-22084 and the apparatus of Japanese patent application publication No. 2013-82487 described above, the action direction of the holding members (specifically, a pair of rollers or a pair of conveyance claws) for bringing the holding members into contact with a bag surface and the action direction of the holding members for opening a bag body are opposite to each other. Thus, compared to a case where the action direction of the holding members for bringing the holding members into contact with a bag surface is the same as the action direction of the holding members for opening the bag, the opening operations of the apparatuses disclosed in Japanese examined utility model (registration) application publication No. 3-22084 and the opening of the device of Japanese patent application publication No. 2013-82487 are inefficient.

[0009] The present invention has been contrived in view of the above circumstances, and an object thereof is to provide an apparatus and a method capable of efficiently opening a bag body in a short period of time. Another object of the present invention is to provide an apparatus and a method capable of opening a bag body while preventing folding marks from being formed on the bag body.

Solution to Problem

[0010] One aspect of the present invention is directed to a bag opening apparatus comprising a gap formation unit which bends at least a front wall portion, of the front wall portion and a back wall portion that constitute a mouth portion of a bag body, so as to form a gap between the front wall portion and the back wall portion, wherein: the gap formation unit includes a first holding unit and a first press drive member which moves the first holding unit between a position where the first holding unit is separated from the front wall portion and a position where the first holding unit is pressed against the front wall portion, the first holding unit includes a contact part, a support part which swingably supports the contact part, and an urging part which urges the contact part via the support part, and when the first press drive member presses the first holding unit against the front wall portion, the contact part is swung against urging force of the urging part while the contact part is in contact with the front wall portion so as to bend the front wall portion.

[0011] The gap formation unit may further include a second holding unit; the first press drive member may move not only the first holding unit but also the second holding unit between the position where the first holding unit and the second holding unit are separated from the front wall portion and the position where the first holding unit and the second holding unit are pressed against the front wall portion; and when the first press drive member presses the first holding unit and the second holding unit against the front wall portion, the contact part of the first holding unit may be swung so as to approach the second holding unit while the contact part of the first holding unit is in contact with the front wall portion.

[0012] The second holding unit may include a contact part, a support part which swingably supports this contact part, and an urging part which urges this contact part via the support part; and when the first press drive member presses the first holding unit and the second holding unit against the front wall portion, the contact part of the second holding unit may be swung against urging force of the urging part of the second holding unit so as to approach the contact part of the first holding unit while the contact part of the second holding unit is in contact with the front wall portion.

[0013] The bag opening apparatus may further comprise an air blowing unit which ejects air toward the gap.

[0014] The gap formation unit may further include: a third holding unit and a fourth holding unit; and a second press drive member which moves the third holding unit and the fourth holding unit between a position where the third holding unit and the fourth holding unit are separated from the back wall portion and a position where the third holding unit and the fourth holding unit are pressed against the back wall portion; and in a state where the contact part of the first holding unit and a contact part of the third holding unit are opposed to each other via the front and back wall portions and the contact part of the second holding unit and a contact part of the fourth holding unit are opposed to each other via the front and back wall portions, the first press drive member may press the first holding unit and the second holding unit against the front wall portion, and the second press drive member may press the third holding unit and the fourth holding unit against the back wall portion.

[0015] The gap formation unit may further include a receiving part which are disposed on a side of the back wall portion and has a receiving surface facing the back wall portion; and the first press drive member may press the first holding unit against the front wall portion in a state where the front wall portion and the back wall portion are sandwiched by the first holding unit and the receiving surface.

[0016] The receiving part may include a first elastic member forming the receiving surface.

[0017] The first holding unit may include: a first link which is attached to the first press drive member and swingably supports one side of the support part of the first holding unit, and a second link which is attached to the first press drive member so as to be capable of moving back and forth and swingably supports another side of the support part of the first holding unit; and when the first press drive member presses the first holding unit against the front wall potion, the urging part of the first holding unit may urge the contact part of the first holding unit, via the second link and the support part of the first holding unit, in a direction including a component of a direction opposing a direction in which the contact part of the first holding unit is swung.

[0018] The contact part may include a second elastic member.

[0019]  The bag opening apparatus may further comprise a pair of grippers which holds both side portions of the bag body, wherein before or while the first press drive member presses the first holding unit against the front wall portion to cause the contact part of the first holding unit to swing, at least one of the grippers is moved in such a manner that a distance between the grippers is reduced.

[0020] Another aspect of the present invention is directed to a bag opening method causing a bag opening apparatus to bend at least a front wall portion, of the front wall portion and a back wall portion that constitute a mouth portion of a bag body, so as to form a gap between the front wall portion and the back wall portion, wherein: the bag opening apparatus includes a gap formation unit having: a first holding unit; and a first press drive member which moves the first holding unit between a position where the first holding unit is separated from the front wall portion and a position where the first holding unit is pressed against the front wall portion, the first holding unit includes a contact part, a support part which swingably supports the contact part, and an urging part which urges the contact part via the support part, and the bag opening method includes a step of bending the front wall portion by causing the first press drive member to press the first holding unit against the front wall portion in such a manner that the contact part is swung against urging force of the urging part while the contact part is in contact with the front wall portion.

[0021] According to the present invention, a bag body can be efficiently opened in a short period of time. Further, according to the present invention, a bag body can be opened while folding marks are prevented from being formed on the bag body.

BRIEF DESCRIPTION OF DRAWINGS

[0022] 

Fig. 1 is a plan view illustrating a schematic configuration of a bag opening apparatus according to a first embodiment.

Fig. 2 is a process diagram of a bag opening method according to the first embodiment.

Fig. 3 is a process diagram of a bag opening method according to the first embodiment.

Fig. 4 is a process diagram of a bag opening method according to the first embodiment.

Fig. 5 is a plan view illustrating an example of a state of a bag body which may occur in the apparatus and the method according to the first embodiment.

Fig. 6 is a plan view illustrating a schematic configuration of a bag opening apparatus according to a second embodiment.

Fig. 7 is a process diagram of a bag opening method according to the second embodiment, showing a state in which the bag opening apparatus is viewed from above.

Fig. 8 is a process diagram of the bag opening method according to the second embodiment, showing a state in which the bag opening apparatus is viewed from above.

Fig. 9 is a process diagram of the bag opening method according to the second embodiment, showing a state in which the bag opening apparatus is viewed from above.

Fig. 10 is a process diagram of the bag opening method according to the second embodiment, showing a state in which the bag opening apparatus is viewed from the side.

Fig. 11 is a process diagram of the bag opening method according to the second embodiment, showing a state in which the bag opening apparatus is viewed from the side.

Fig. 12 is a process diagram of the bag opening method according to the second embodiment, showing a state in which the bag opening apparatus is viewed from the side.

Fig. 13 is a process diagram of the bag opening method according to the second embodiment, showing a state in which the bag opening apparatus is viewed from the side.

Fig. 14 is a plan view illustrating a schematic configuration of a bag opening apparatus according to a first modified example.

DESCRIPTION OF EMBODIMENTS

[0023] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0024] In the following embodiments, bag opening apparatuses used in a packaging machine will be described as an example, but the bag opening apparatuses and bag opening methods described below may be applied to any mechanism using a bag body of which the mouth portion is opened. A packaging machine typically includes, in addition to a bag opening apparatus, a device which introduces the contents into a bag body through the opened mouth portion, a device which closes and seals the mouth portion after the contents have been introduced into the bag body, and other devices. The form of the contents to be introduced into a bag body is not limited, and it is possible to introduce contents in the form of gas, liquid, gel or solid or contents having two or more forms, into a bag body.

[0025] In a bag opening apparatus and a bag opening method according to the embodiment described below, first, the close contact between the front wall portion and the back wall portion at the opening portion of a bag body is partially released by forming a gap in the mouth portion, and then the whole of the bag body is opened by blowing compressed air into the inside of the bag body through the gap in the mouth portion. The opening process of a bag body may be performed through a plurality of processes in this way, but may be performed in a single process. Specifically, the process of forming a gap in the mouth portion of a bag body itself also corresponds to the opening process of a bag body in a broad sense. Therefore, if the mouth portion of a bag body can be opened to a desired state only by the process of forming a gap in the mouth portion of the bag body, other processes (for example, a process of blowing compressed air into the inside of the bag body) are not necessarily required to be performed.

[0026] The bag opening apparatus described below comprises: a gap formation unit which bends at least the front wall portion, of the front wall portion and the back wall portion constituting the mouth portion of a bag body, in such a manner that a gap is formed between the front wall portion and the back wall portion at the mouth portion; and an air blowing unit which blows air toward the gap. Specifically, as typical examples of a bag opening apparatus according to the present invention, there are a bag opening apparatus which bends both the front wall portion and the back wall portion of a bag body, and a bag opening apparatus which bends only one of the front wall portion and the back wall portion. In the following first embodiment, a bag opening apparatus that bends each of the front wall portion and the back wall portion of a bag body to form a gap will be exemplified. On the other hand, in the second embodiment below, a bag opening apparatus that bends only the front wall portion, of the front wall portion and the back wall portion of a bag body, to form a gap is exemplified.

[First Embodiment]

[0027] Fig. 1 is a plan view illustrating a schematic configuration of a bag opening apparatus 10 according to a first embodiment.

[0028] The mouth portion 101 of a bag body 100 to be supplied to the bag opening apparatus 10 is closed. Specifically, in a state in which both the side portions (in particular, both the side edge portions) of a bag body 100 are held by a pair of grippers 110 and the front wall portion 102 and the back wall portion 103 of the bag body 100 are in close contact with each other, the bag body 100 is supplied to the bag opening apparatus 10. In particular, each bag body 100 is transferred together with a pair of grippers 110 along a predetermined track extending in the horizontal direction (for example, a straight line track, a circle track, or a track formed by combining a straight line and a curved line) so as to sequentially visit a plurality of stations, and is intermittently stopped at the opening station S1 where the bag opening apparatus 10 is provided. Each bag body 100 is opened by the bag opening apparatus 10 while stopping at the opening station S1. A bag body 100 having the mouth portion 101 opened by the bag opening apparatus 10 is intermittently transferred toward the other stations (a content introduction station, a sealing station, etc.) provided in the subsequent stages.

[0029] A pair of grippers 110 is provided so as to be movable in a direction of the horizontal direction parallel to the extension direction (see the arrow "Y" in Fig. 1) in which a bag body 100 extends. When the bag opening apparatus 10 is brought into contact with a bag body 100 at the opening station S1, the grippers 110 forming a pair are disposed at positions separated relatively from each other, the bag body 100 is strained in the Y direction by the pair of grippers 110, and each of the front wall portion 102 and the back wall portion 103 of the bag body 100 is placed in a stretched state without looseness. On the other hand, when the bag opening apparatus 10 bends the front wall portion 102 and the back wall portion 103 as described later, the grippers 110 forming a pair are disposed in positions relatively close to each other, the tension of the bag body 100 in the Y direction is released, and each of the front wall portion 102 and the back wall portion 103 of the bag body 100 is placed in a slack state.

[0030] The gap formation unit 11 of the bag opening apparatus 10 of the present embodiment includes: a first press drive member 23 (a first movement arm) and a second press drive member 24 (a second movement arm); a first holding unit 25 and a second holding unit 26 which are attached to the first press drive member 23; and a third holding unit 27 and a fourth holding unit 28 which are attached to the second press drive member 24.

[0031] A first opening unit 21 includes the first press drive member 23, the first holding unit 25 and the second holding unit 26, and moves in an integrated fashion. Similarly, a second opening unit 22 includes the second press drive member 24, the third holding unit 27 and the fourth holding unit 28, and moves in an integrated fashion. A bag body 100 gripped by the grippers 110 is disposed between the first opening unit 21 and the second opening unit 22, the first opening unit 21 is arranged on the front surface side of the bag body 100, and the second opening unit 22 is arranged on the back surface side of the bag body 100. The first to the fourth holding units 25 to 28 are disposed above the grippers 110 in terms of the vertical direction, and when the first to the fourth holding units 25 to 28 contact the bag body 100, the first to the fourth holding units 25 to 28 contact the bag body 100 at positions close to the mouth portion 101.

[0032] Each of the first press drive member 23 and the second press drive member 24 is provided so as to be driven to be horizontally movable in directions toward and away from each other (see an arrow "X" in Fig. 1) by a drive unit which is not illustrated (such as an air cylinder or a motor), and moves forward and backward relative to the bag body 100.

[0033] The first press drive member 23 moves the first holding unit 25 and the second holding unit 26 between a position where the first holding unit 25 and the second holding unit 26 are distanced from the front wall portion 102 of a bag body 100 and a position where the first holding unit 25 and the second holding unit 26 are pressed against the front wall portion 102. The second press drive member 24 moves the third holding unit 27 and the fourth holding unit 28 between a position where the third holding unit 27 and the fourth holding unit 28 are distanced from the back wall portion 103 of a bag body 100 and a position where the third holding unit 27 and the fourth holding unit 28 are pressed against the back wall portion 103.

[0034] The first holding unit 25 and the second holding unit 26 are provided at positions distanced from each other in the Y direction, and the third holding unit 27 and the fourth holding unit 28 are provided at positions distanced from each other in the Y direction. The first holding unit 25 and the second holding unit 26 are each arranged to protrude from the first press drive member 23 toward the bag body 100. The third holding unit 27 and the fourth holding unit 28 of the second opening unit 22 are each arranged to protrude from the second press drive member 24 toward the bag body 100.

[0035] For example, when the first press drive member 23 is moved in a direction in which the first press drive member 23 approaches the second press drive member 24, the first holding unit 25 and the second holding unit 26 contact areas of the front wall portion 102 of the bag body 100 which are distanced from each other in the Y direction, and the first holding unit 25 and the second holding unit 26 are pressed against the front wall portion 102. Similarly, when the second press drive member 24 is moved in a direction in which the second press drive member 24 approaches the first press drive member 23, the third holding unit 27 and the fourth holding unit 28 contact areas of the back wall portion 103 of the bag body 100 which are distanced from each other in the Y direction, and the third holding unit 27 and the fourth holding unit 28 are pressed against the back wall portion 103.

[0036] Each of the first holding unit 25, the second holding unit 26, the third holding unit 27, and the fourth holding unit 28 includes a contact part 31, a support part 32 that swingably supports the contact part 31, and an urging part 33 which urges the contact part 31 via the support part 32.

[0037] The contact parts 31 of the first holding unit 25 and the second holding unit 26 are regions which directly contact the front wall portion 102 when the first press drive member 23 presses the first holding unit 25 and the second holding unit 26 against the front wall portion 102. Further, the contact parts 31 of the third holding unit 27 and the fourth holding unit 28 are regions which directly contact the back wall portion 103 when the second press drive member 24 presses the third holding unit 27 and the fourth holding unit 28 against the back wall portion 103. The contact parts 31 of the present embodiment include an elastic member (second elastic member). Although the elastic member of the contact parts 31 is not limited, the elastic member of the contact parts 31 is preferably a member having a high friction coefficient and excellent adhesion, and typically silicone or urethane may be used as the elastic member of the contact parts 31. As will be described later, in the bag opening apparatus 10 of the present embodiment, the contact parts 31 of the first holding unit 25 to the fourth holding unit 28 displace the bag surfaces of a bag body 100 (that is, the front wall portion 102 and the back wall portion 103) from each other due to the friction force so as to form a gap in the mouth portion 101 of the bag body 100. Therefore, by configuring the contact parts 31 of the first holding unit 25 to the fourth holding unit 28 with an elastic member as described above, the grip force of the contact parts 31 is secured and thereby the opening process of a bag body 100 is stabilized, and further, it is possible to make a bag body 100 less likely to be damaged by the contact parts 31.

[0038] In the illustrated first holding unit 25, a link mechanism is constituted by a first link 34, a second link 35, and the support part 32. The first link 34 is fixedly attached to the first press drive member 23, protrudes from the first press drive member 23 toward a bag body 100 (specifically, in the horizontal direction (that is, the X direction) perpendicular to the Y direction), and supports one side of the support part 32 via a second support shaft 42 in a swingable manner. A distal end portion on one side of the second link 35 swingably supports the other side of the support part 32 via a first support shaft 41. The other side of the second link 35 is swingably attached to the first press drive member 23 via a third support shaft 43 (a fastening part), and is provided to be movable back and forth in a direction toward the bag body 100 and in a direction away from the bag body 100.

[0039] The illustrated second link 35 has a reduced diameter portion 36 having a small diameter in part between the third support shaft 43 and a connecting portion between the second link 35 and the support part 32 of the first holding unit 25. An urging part 33 constituted by a compressed spring is disposed in this reduced diameter portion 36. The urging part 33 of the first holding unit 25 urges the support part 32 and the second link 35 of the first holding unit 25 toward the connection portion between the second link 35 and the support part 32 of the first holding unit. Specifically, the urging part 33 of the first holding unit 25 urges the contact part 31 of the first holding unit 25, via the support part 32 and the second link 35 of the first holding unit 25, in a direction including a component of the direction opposing a direction in which the contact part 31 of the first holding unit 25 swings when the first press drive member 23 presses the first holding unit 25 against the front wall portion 102. In particular, the urging part 33 of the first holding unit 25 of the present embodiment is combined with the above-described link mechanism to urge the second link 35 and the support part 32 in such a manner that the contact part 31 of the first holding unit 25 is distanced from the contact part 31 of the second holding unit 26.

[0040] The support part 32 of the first holding unit 25 is disposed in a posture tilted with respect to the movement direction (that is, the X direction) of the first opening unit 21 and the second opening unit 22. In particular, the tip of the support part 32 of the first holding unit 25 on the side where the contact part 31 is disposed (specifically, the tip relatively close to the bag body 100) is arranged closer to the second holding unit 26 in the Y direction than the opposite tip (specifically, the tip relatively farther from the bag body 100). Thus, when the first holding unit 25 (in particular, the contact part 31) is pressed against the bag body 100, the support part 32 and the contact part 31 of the first holding unit 25 swing so as to approach the support part 32 and the contact part 31 of the second holding unit 26.

[0041] The second holding unit 26 has a configuration similar to the above-described first holding unit 25. Specifically, the second holding unit 26 includes a first link 34, a second link 35, a reduced diameter portion 36, a first support shaft 41, a second support shaft 42 and a third support shaft 43 in addition to the contact part 31, the support part 32 and the urging part 33. However, the urging part 33 of the second holding unit 26 is combined with the link mechanism constituted by the support part 32, the first link 34 and the second link 35 of the second holding unit 26 to urge the second link 35 and the support part 32 in such a manner that the contact part 31 of the second holding unit 26 is distanced from the contact part 31 of the first holding unit 25. Specifically, the urging part 33 of the second holding unit 26 urges the contact part 31 of the second holding unit 26, via the support part 32 and the second link 35 of the second holding unit 26, in a direction including a component of the direction opposing a direction in which the contact part 31 of the second holding unit 26 swings when the first press drive member 23 presses the second holding unit 26 against the front wall portion 102.

[0042] The third holding unit 27 and the fourth holding unit 28 attached to the second press drive member 24 have configurations similar to the first holding unit 25 and the second holding unit 26 attached to the first press drive member 23, and each include a contact part 31, a support part 32, an urging part 33, a first link 34, a second link 35, a reduced diameter portion 36, a first support shaft 41, a second support shaft 42, and a third support shaft 43.

[0043] In each of the third holding unit 27 and the fourth holding unit 28, the first link 34 is fixedly attached to the second press drive member 24, protrudes from the second press drive member 24 towards the bag body 100 in the X direction, and supports one side of the support part 32 via the second support shaft 42 in a swingable manner. Further, the second link 35 of each of the third holding unit 27 and the fourth holding unit 28 is swingably attached to the second press drive member 24 via the third support shaft 43 (a fastening part), is provided to be movable back and forth in a direction towards the bag body 100 and in a direction away from the bag body 100, and supports the other side of the support part 32 via the first support shaft 41 in a swingable manner.

[0044] The urging part 33 of the third holding unit 27 is combined with the link mechanism constituted by the support part 32, the first link 34 and the second link 35 of the third holding unit 27 to urge the second link 35 and the support part 32 in such a manner that the contact part 31 of the third holding unit 27 is distanced from the contact part 31 of the fourth holding unit 28. Further, the urging part 33 of the fourth holding unit 28 is combined with the link mechanism constituted by the support part 32, the first link 34 and the second link 35 of the fourth holding unit 28 to urge the second link 35 and the support part 32 in such a manner that the contact part 31 of the fourth holding unit 28 is distanced from the contact part 31 of the third holding unit 27.

[0045] As described above, when the first press drive member 23 presses the first holding unit 25 and the second holding unit 26 against the front wall portion 102, the support part 32 and the contact part 31 of the first holding unit 25 swing against the urging force of the urging part 33 of the first holding unit 25 in such a manner that the contact part 31 of the first holding unit 25 approaches the contact part 31 of the second holding unit 26. Specifically, when the first press drive member 23 presses the first holding unit 25 against the front wall portion 102, the contact part 31 of the first holding unit 25 swings against the urging force of the urging part 33 of the first holding unit 25 while contacting the front wall portion 102 and thereby bends the front wall portion 102. In addition, when the first press drive member 23 presses the first holding unit 25 and the second holding unit 26 against the front wall portion 102, the support part 32 and the contact part 31 of the second holding unit 26 swing against the urging force of the urging part 33 of the second holding unit 26 in such a manner that the contact part 31 of the second holding unit 26 approaches the contact part 31 of the first holding unit 25. In this way, when the first press drive member 23 presses the second holding unit 26 against the front wall portion 102, the contact part 31 of the second holding unit 26 swings against the urging force of the urging part 33 of the second holding unit 26 and thereby bends the front wall portion 102. As described above, when the first press drive member 23 presses the first holding unit 25 and the second holding unit 26 against the front wall portion 102, at least one of the contact part 31 of the first holding unit 25 and the contact part 31 of the second holding unit 26 is swung in such a manner that the distance between the contact part 31 of the first holding unit 25 and the contact part 31 of the second holding unit 26 is made smaller, and thereby the front wall portion 102 is bent and a gap can be created in the mouth portion 101.

[0046] In particular, in the present embodiment, in a situation where the contact part 31 of the first holding unit 25 and the contact part 31 of the third holding unit 27 are opposed to each other via the front wall portion 102 and the back wall portion 103 of the bag body 100 while the contact part 31 of the second holding unit 26 and the contact part 31 of the fourth holding unit 28 are opposed to each other via the front wall portion 102 and the back wall portion 103 of the bag body 100, the first press drive member 23 presses the first holding unit 25 and the second holding unit 26 against the front wall portion 102, and the second press drive member 24 presses the third holding unit 27 and the fourth holding unit 28 against the back wall portion 103. Thus, the first holding unit 25 (for example, the contact part 31, the support part 32 and the second link 35) and the third holding unit 27 (for example, the contact part 31, the support part 32 and the second link 35) behave in a symmetric fashion with respect to the bag body 100, and the second holding unit 26 and the fourth holding unit 28 also behave in a symmetric fashion with respect to the bag body 100.

[0047] Meanwhile, the air blowing unit 12 is installed above the mouth portion 101 of a bag body 100 with respect to the vertical direction, and the ejection port 45 of the air blowing unit 12 is directed towards the mouth portion 101 of the bag body 100. The air blowing unit 12 is connected to an air supply source (not shown), and compresses the air from the air supply source and ejects the compressed air from the ejection port 45. Although the illustrated air blowing unit 12 has the ejection port 45 in the form of a nozzle, the air blowing unit 12 and the ejection port 45 may take any form capable of appropriately ejecting compressed air.

[0048] Typically, the ejection port 45 of the air blowing unit 12 is disposed above the center position of the mouth portion 101 of a bag body 100; however, the relative arrangement position and direction of the ejection port 45 with respect to the mouth portion 101 of a bag body 100 are not limited. For example, the ejection port 45 of the air blowing unit 12 may be oriented so as to eject compressed air in an oblique direction with respect to the mouth portion 101 of a bag body 100. Further, the ejection port 45 of the air blowing unit 12 may be oriented so as to eject compressed air toward a position of the mouth portion 101 of a bag body 100 other than the center position.

[0049] Next, a bag opening method according to which a gap is formed between the front wall portion 102 and the back wall portion 103 of a bag body 100 and the bag body 100 is opened will be described.

[0050] A bag opening method performed by using the above-described bag opening apparatus 10 includes: a step of bending both the front wall portion 102 and the back wall portion 103 to form a gap between the front wall portion 102 and the back wall portion 103; and a step of blowing compressed air from the air blowing unit 12 into the gap formed in the bag mouth to spread the inside of the bag body 100 with the compressed air.

[0051] Figs. 2 to 4 are process diagrams of a bag opening method according to the first embodiment.

[0052] First, as shown in Fig. 2, the first opening unit 21 (the first press drive member 23, the first holding unit 25 and the second holding unit 26) and the second opening unit 22 (the second press drive member 24, the third holding unit 27 and the fourth holding unit 28) are arranged at positions separated from a bag body 100 gripped by a pair of grippers 110.

[0053] Then, as shown in Fig. 3, the first opening unit 21 and the second opening unit 22 are moved to approach each other in such a manner that the contact parts 31 of the first holding unit 25 to the fourth holding unit 28 are brought into contact with the bag body 100. As a result, the contact part 31 of the first holding unit 25 and the contact part 31 of the third holding unit 27 are opposed to each other with the bag body 100 interposed therebetween, and the contact part 31 of the second holding unit 26 and the contact part 31 of the fourth holding unit 28 are opposed to each other with the bag body 100 interposed therebetween.

[0054] The contact timing of the first holding unit 25 to the fourth holding unit 28 with respect to the bag body 100 is not limited. All of the first holding unit 25 to the fourth holding unit 28 may be brought into contact with the bag body 100 at almost the same time, or one of the set of the first holding unit 25 and the second holding unit 26 (that is, the first opening unit 21) and the set of the third holding unit 27 and the fourth holding unit 28 (that is, the second opening unit 22) may come into contact with the bag body 100 prior to the other.

[0055] Then, as shown in Fig. 4, both the first opening unit 21 and the second opening unit 22 are further moved toward the bag body 100, so that the front wall portion 102 and the back wall portion 103 of the bag body 100 are bent. Specifically, the first press drive member 23 presses the first holding unit 25 and the second holding unit 26 against the front wall portion 102 to force the support part 32 of the first holding unit 25 to swing against the urging force of the urging part 33 of the first holding unit 25 and to force the support part 32 of the second holding unit 26 to swing against the urging force of the urging part 33 of the second holding unit 26 in such a manner that the contact part 31 of the first holding unit 25 and the contact part 31 of the second holding unit 26 approach each other. Similarly, the second press drive member 24 presses the third holding unit 27 and the fourth holding unit 28 against the back wall portion 103 to force the support part 32 of the third holding unit 27 to swing against the urging force of the urging part 33 of the third holding unit 27 and to force the support part 32 of the fourth holding unit 28 to swing against the urging force of the urging part 33 of the fourth holding unit 28 in such a manner that the contact part 31 of the third holding unit 27 and the contact part 31 of the fourth holding unit 28 approach each other.

[0056] In this way, the contact parts 31 of the first holding unit 25 to the fourth holding unit 28 are moved inward in the width direction of the bag body 100 in a state of contacting the bag surfaces of the bag body 100, so that the front wall portion 102 and the back wall portion 103 of the bag body 100 are displaced inward in the width direction. As a result, a gap is formed in the mouth portion 101 and the bag body 100 is opened. In this situation, the grippers 110 forming a pair are moved to approach each other while the grippers 110 grip both side portions (particularly both side edge portions) of the bag body 100, so that the front wall portion 102 and the back wall portion 103 are loosened to the extent that a gap can be formed in the mouth portion 101. It is preferable that this approaching movement of the pair of grippers 110 be carried out after the contact parts 31 of the first holding unit 25 to the fourth holding unit 28 have contacted the bag body 100 (see Fig. 3). Further, it is preferable that the approaching movement of the pair of grippers 110 be carried out before the contact part 31 of the first holding unit 25 and the contact part 31 of the second holding unit 26 come close to each other and before the contact part 31 of the third holding unit 27 and the contact part 31 of fourth holding unit 28 come close to each other. Alternatively, it is preferable that the approaching movement of the pair of grippers 110 be carried out simultaneously with the time when the contact part 31 of the first holding unit 25 and the contact part 31 of the second holding unit 26 come close to each other and simultaneously with the contact part 31 of the third holding unit 27 and the contact part 31 of fourth holding unit 28 come close to each other.

[0057] As described above, before or during swinging of the contact part 31 of the first holding unit 25 by the first press drive member 23 pressing the first holding unit 25 against the front wall portion 102, at least one of the grippers 110 forming a pair (both the grippers 110 in the present embodiment) is moved in such a manner that the distance between the grippers 110 forming a pair becomes smaller.

[0058] Then, compressed air is blown from the air blowing unit 12 (see Fig. 1) toward the gap in the mouth portion 101 of the bag body 100, although the illustration in the drawings is omitted. As a result, the compressed air is supplied to the interior of the bag body 100, which enables the inside of the bag body 100 to spread up to the bag bottom.

[0059] As described above, according to the bag opening apparatus 10 and the bag opening method of the present embodiment, negative pressure suction using a suction cup or the like is not used in the opening process of a bag body 100. Thus, the period of time for forming a negative pressure is not required, the period of time for the opening process can be shortened, and the processing can be performed at high speed.

[0060] In general, a bag opening method using suction cups requires: (1) a step of pressing the suction cups against the front surface and the back surface of a bag body respectively; (2) a step of performing deairing and forming a negative pressure between each suction cup and the bag surface; (3) a step of measuring the pressure between the suction cup and the bag surface after elapse of a predetermined time from the start of the deairing; (4) a step of distancing the suction cups from each other to form a gap in the mouth portion; and (5) a step of blowing compressed air toward the gap. In particular, the above-mentioned "(2) a step for forming a negative pressure" requires a decent period of time, and if a decent time is not secured for "(2) a step for forming a negative pressure", it is not possible for each suction cup to adequately suck the bag surface and thus the bag body cannot be properly opened.

[0061] In contrast, the bag opening method according to the present embodiment includes: (a) a step of bringing the first holding unit 25 to the fourth holding unit 28 into contact with a bag body 100; (b) a step of pressing the first holding unit 25 to the fourth holding unit 28 against the bag body 100 to form a gap in the mouth portion 101; and (c) a step of blowing compressed air into the gap. As described above, according to the above-described embodiment, a step itself of forming a negative pressure is unnecessary, and a gap can be appropriately created in the mouth portion 101 of a bag body 100 by just the actions of pressing the first holding unit 25 to the fourth holding unit 28 against a bag body 100.

[0062] In particular, by moving a pair of holding units (that is, "a set of the first holding unit 25 and the second holding unit 26" or "a set of the third holding unit 27 and the fourth holding unit 28") toward a bag body 100, it is possible not only to bring the contact parts 31 of the pair of holding units into contact with the bag body 100 but also to move the pair of contact parts 31 inward in the width direction of the bag body 100. Specifically, the first holding unit 25 to the fourth holding unit 28 of the present embodiment can be moved inward in the width direction almost simultaneously with the contact with a bag body 100 so that the front wall portion 102 and the back wall portion 103 of the bag body 100 are bent. As described above, "(a) the step of bringing the first holding unit 25 to the fourth holding unit 28 into contact with a bag body 100" and "(b) a step of forming a gap in the mouth portion 101" can be performed in a sequential processing in which the first opening unit 21 and the second opening unit 22 are moved toward a bag body 100, and therefore it is possible to form a gap in the mouth portion 101 very efficiently in a short time.

[0063] By forming a gap in the mouth portion 101 of a bag body 100 in a short time in this way, "(c) a step of blowing compressed air into the gap" performed subsequently can be expedited. As a result, it is possible to allocate a sufficient time to "(c) a step of blowing compressed air into the gap" and thereby open a bag body 100 more reliably with compressed air. Further, it is also possible to shorten the period of time required for the entire opening process including the above (a) to (c) steps.

[0064] Incidentally, when the inventors measured the period of time required for the above-described series of steps (that is, the above-mentioned (a) to (c) steps) using the bag opening apparatus 10 according to the above-described first embodiment, it took approximately 0.15 seconds for one bag body 100. In contrast, when the inventors measured the period of time required for the above-described series of steps (that is, the above-mentioned (1) to (5) steps) using a conventional apparatus with suction cups, it took approximately 0.5 seconds for one bag body 100. As described above, according to the bag opening apparatus 10 of the present embodiment, it is possible to perform the opening process of a bag body 100 at least approximately three times faster than the conventional apparatus.

[0065] Further, in the bag opening apparatus 10 of the present embodiment, a negative pressure forming means, such as a vacuum pump, is unnecessary, and there is no need to control such a negative pressure forming means. In particular, in a conventional apparatus using suction cups, a common negative pressure forming means, such as a pump, is typically connected to a plurality of suction cups in many cases, and in such a conventional apparatus, there is concern that a problem occurring in one suction cup may affect another suction cup. In contrast, in the bag opening apparatus 10 of the present embodiment, there is no concern of such propagation of problem.

[0066] In the present embodiment, the opening process of a bag body 100 is performed by combining a step of moving the first opening unit 21 (in particular, the first press drive member 23) and the second opening unit 22 (in particular, the second press drive member 24), a step of moving the pair of grippers 110, and a step of blowing air from the air blowing unit 12. The driving of these elements may be controlled by a control unit (not shown) according to the driving state of one another, or may be performed based on predetermined timing. For example, the control unit may monitor the movement amounts and the arrangement positions of the first press drive member 23 and the second press drive member 24, and may move the grippers 110 or may cause the air blowing unit 12 to eject compressed air according to these movement amounts and arrangement positions. Further, the time when the movement of the first press drive member 23 and the second press drive member 24 is performed, the time when the movement of the grippers 110 is performed, and the time when the air ejection of the air blowing unit 12 is performed, may be determined in advance within the time period when a bag body 100 is intermittently stopped and stays at the opening station S1. Further, the movement of the first press drive member 23 and the second press drive member 24, the movement of the grippers 110, and the air ejection of the air blowing unit 12 may be performed by combining the control based on the drive states and the driving based on the time determined in advance.

[Second Embodiment]

[0067] In a bag opening apparatus 10 of the present embodiment, elements which are the same as or similar to those of the above-described bag opening apparatus 10 of the first embodiment are denoted by the same reference numerals, and the detailed description thereof will be omitted.

[0068] Fig. 5 is a plan view illustrating an example of a state of a bag body 100 which may occur in the apparatus and the method according to the first embodiment. According to the bag opening apparatus 10 and the bag opening method according to the above-described first embodiment, when the front wall portion 102 and the back wall portion 103 of a bag body 100 bend in mutually different directions in terms of the X direction as shown in Fig. 4, a desired gap can be formed in the mouth portion 101 of the bag body 100. On the other hand, when the front wall portion 102 and the back wall portion 103 of a bag body 100 bend in the same direction with respect to the X direction as shown in Fig. 5, a desired gap is not formed in the mouth portion 101 of the bag body 100.

[0069] A bag opening apparatus 10 and a bag opening method according to the present embodiment can effectively avoid the trouble shown in Fig. 5, and can form a gap between the front wall portion 102 and the back wall portion 103 more reliably so that the bag body 100 can be properly opened.

[0070] Fig. 6 is a plan view illustrating a schematic configuration of a bag opening apparatus 10 according to the second embodiment.

[0071] In the bag opening apparatus 10 according to the present embodiment, the first opening unit 21 has almost the same configuration as that of the above-described first embodiment, but the second opening unit 22 has a receiving part 50 instead of the third holding unit 27 and the fourth holding unit 28. Specifically, the gap formation unit 11 according to the present embodiment includes a receiving part 50 (i.e., a receiving plate in the illustrated example) disposed on the back wall portion 103 side, and the receiving part 50 has a receiving surface 51. The receiving surface 51 extends in parallel with the extension direction (that is, the Y direction) of the back wall portion 103 of a bag body 100 gripped by a pair of grippers 110, and is disposed above the grippers 110 with respect to the vertical direction. The receiving part 50 includes an elastic member 52 (first elastic member) that forms the receiving surface 51, and the elastic member 52 is typically silicone or urethane.

[0072] The second press drive member 24 to which the receiving part 50 is attached can be moved in the same manner as in the above-described first embodiment, and can advance and retreat the receiving surface 51 of the receiving part 50 with respect to the bag body 100 (in particular, the back wall portion 103). While the second press drive member 24 of the present embodiment brings the receiving surface 51 of the receiving part 50 into contact with the back wall portion 103 of the bag body 100, the second press drive member 24 basically does not press the receiving part 50 (receiving surface 51) against the back wall portion 103. The receiving surface 51 of the receiving part 50 acts as a pressing surface for the first holding unit 25 and the second holding unit 26 when the first holding unit 25 and the second holding unit 26 are caused to be swung. When the first holding unit 25 and the second holding unit 26 are pressed against the front wall portion 102 of a bag body 100, the receiving surface 51 is fixedly arranged, and pushes back the first holding unit 25 and the second holding unit 26 while supporting the back wall portion 103. As a result, when the first holding unit 25 and the second holding unit 26 are pressed against the front wall portion 102 of a bag body 100, the back wall portion 103 of the bag body 100 is held on the receiving surface 51 and basically keeps its almost planar state at the same position, and only the front wall portion 102 is bent by the first holding unit 25 and the second holding unit 26. However, the second press drive member 24 may press the receiving part 50 (receiving surface 51) against the back wall portion 103. In this case, the back wall portion 103 may be tensioned by the force received from the receiving surface 51 of the receiving part 50 while an excessive load is not applied to the bag body 100 (in particular, the back wall portion 103) from the receiving surface 51 of the receiving part 50 and the flat state of the back wall portion 103 along the receiving surface 51 is maintained.

[0073] The other configuration is almost the same as that of the above-described first embodiment.

[0074] The bag opening method using the bag opening apparatus 10 of the present embodiment described above includes: a step of bending the front wall portion 102 of a bag body 100 to form a gap between the front wall portion 102 and the back wall portion 103; and a step of blowing compressed air from the air blowing unit 12 toward the gap formed in the bag mouth to spread the interior of the bag body 100 with the compressed air. The back wall portion 103 of the bag body 100 is supported by the receiving surface 51 of the receiving part 50 and basically maintains a state of extending linearly in the Y direction.

[0075] Figs. 7 to 9 are process diagrams of a bag opening method according to the second embodiment, showing states in which the bag opening apparatus is viewed from above. Figs. 10 to 13 are process diagrams of the bag opening method according to the second embodiment, showing states in which the bag opening apparatus is viewed from the side. In Figs. 10 to 13, the arrow marked with "Z" corresponds to the vertical direction.

[0076] First, as shown in Figs. 7 and 10, the first opening unit 21 (the first press drive member 23, the first holding unit 25 and the second holding unit 26) and the second opening unit 22 (the second press drive member 24 and the receiving part 50) are arranged at positions separated from a bag body 100 gripped by a pair of grippers 110 in the horizontal direction (in particular, the X direction).

[0077] Then, as shown in Figs. 8 and 11, the first opening unit 21 and the second opening unit 22 are moved to approach each other in such a manner that the first holding unit 25 and the second holding unit 26 are brought into contact with the front wall portion 102 of the bag body 100 and the receiving surface 51 of the receiving part 50 is brought into contact with the back wall portion 103 of the bag body 100. As a result, the first holding unit 25 and the second holding unit 26 are opposed to the receiving surface 51 of the receiving part 50 via the bag body 100.

[0078] The contact timing of the first holding unit 25, the second holding unit 26 and the receiving surface 51 of the receiving part 50 with respect to the bag body 100 is not limited. All of the first holding unit 25, the second holding unit 26 and the receiving part 50 may be brought into contact with the bag body 100 at almost the same time, or one of the receiving part 50 (that is, the second opening unit 22) and a set of the first holding unit 25 and the second holding unit 26 (that is, the first opening unit 21) may come into contact with the bag body 100 prior to the other. For example, by bringing the receiving part 50 into contact with the bag body 100 (specifically, the back wall portion 103) prior to the first holding unit 25 and the second holding unit 26, the first holding unit 25 and the second holding unit 26 can subsequently perform the contact operation and the pressing operation with respect to the bag body 100 (specifically, the front wall portion 102) in a continuous manner without stopping.

[0079] Then, as shown in Figs. 9 and 12, the first opening unit 21 is further moved toward the bag body 100 so that the front wall portion 102 of the bag body 100 is bent. Specifically, the first holding unit 25 and the second holding unit 26 are pressed against the front wall portion 102 by the first press drive member 23, and thereby the support part 32 of the first holding unit 25 is swung against the urging force of the urging part 33 of the first holding unit 25 and the support part 32 of the second holding unit 26 is swung against the urging force of the urging part 33 of the second holding unit 26 so that the contact part 31 of the first holding unit 25 and the contact part 31 of the second holding unit 26 approach each other.

[0080] On the other hand, while the contact part 31 of the first holding unit 25 and the contact part 31 of the second holding unit 26 approach each other, the receiving part 50 is stopped in a state of being in contact with the back wall portion 103 of the bag body 100, and the back wall portion 103 is supported on the receiving surface 51 of the receiving part 50 and is kept almost parallel to the Y direction.

[0081] As described above, in a state where the front wall portion 102 and the back wall portion 103 are sandwiched between the receiving surface 51 and each of the first holding unit 25 and the second holding unit 26, the first press drive member 23 further presses the first holding unit 25 and the second holding unit 26 against the front wall portion 102. As a result, the first holding unit 25 and the second holding unit 26 move inward in the width direction of the bag body 100 while being pressed against the front wall portion 102 of the bag body 100. In this way, by moving the contact part 31 of the first holding unit 25 and the contact part 31 of the second holding unit 26 placed in contact with the front wall portion 102 inward in the width direction of the bag body 100, the front wall portion 102 of the bag body 100 is displaced inward in the width direction. As a result, a gap is formed in the mouth portion 101 of the bag body 100.

[0082] Then, as shown in Fig. 13, compressed air is blown from the air blowing unit 12 toward the gap in the mouth portion 101 of the bag body 100. As a result, the compressed air enters into the bag body 100, enabling the inside of the bag body 100 to spread to the bag bottom.

[0083] As described above, according to the bag opening apparatus 10 and the bag opening method of the present embodiment, a bag body 100 can be opened. In particular, since the opening process of a bag body 100 is performed in a state where the back wall portion 103 of the bag body 100 is supported by the receiving part 50, the problem that the front wall portion 102 and the back wall portion 103 of the bag body 100 are bent in the same direction as each other (see Fig. 5) can be effectively avoided.

[Modified Examples]

[0084] The present invention is not limited to the above-described embodiments and modified examples. For example, various modifications may be made to each element of the embodiments and the modified examples described above.

[First Modified Example]

[0085] Fig. 14 is a plan view illustrating a schematic configuration of a bag opening apparatus 10 according to a first modified example.

[0086] In the first holding unit 25 to the fourth holding unit 28 of the above-described embodiments, the first link 34 is fixedly provided with respect to the first press drive member 23 or the second press drive member 24; however, the first link 34 may be provided so as to be capable of swinging with respect to the first press drive member 23 or the second press drive member 24.

[0087] The first links 34 of the first holding unit 25 and the second holding unit 26 according to the present modified example shown in Fig. 14 each have an end on one side connected swingably to the first press drive member 23 via the third support shaft 43, and each have an end on the other side connected swingably to one side of the support part 32 via the second support shaft 42. The other configuration is almost the same as that of the bag opening apparatus 10 of the above-described second embodiment.

[0088] In this modified example, the first link 34, the second link 35 and the support part 32 of each of the first holding unit 25 and the second holding unit 26 constitute a link mechanism. The urging part 33 of the first holding unit 25 is combined with this link mechanism to urge the support part 32 and the second link 35 of the first holding unit 25 in such a manner that the contact part 31 of the first holding unit 25 is distanced from the contact part 31 of the second holding unit 26. Further, the urging part 33 of the second holding unit 26 is combined with this link mechanism to urge the support part 32 and the second link 35 of the second holding unit 26 in such a manner that the contact part 31 of the second holding unit 26 is distanced from the contact part 31 of the first holding unit 25. Thus, by causing the first press drive member 23 to press the contact part 31 of the first holding unit 25 and the contact part 31 of the second holding unit 26 against the front wall portion 102 of a bag body in a state in which the back wall portion 103 of the bag body 100 is supported by the receiving surface 51 of the receiving part 50, the front wall portion 102 can be bent to form a gap in the mouth portion 101.

[0089] While Fig. 14 shows an example in which a first link 34 provided swingably is applied to the above-described second embodiment, this first link 34 may be applied to the above-described first embodiment. Specifically, not only in the first holding unit 25 and the second holding unit 26 but also in the third holding unit 27 and the fourth holding unit 28, the end of one side of a first link 34 may be swingably attached to the second press drive member 24 via the third support shaft 43, and the end of the other side of the first link 34 is swingably attached to one side of the support part 32 via the second support shaft 42.

[Other Modified Examples]

[0090] For example, the bag opening apparatus 10 may supplementarily utilize a suction cup. As a specific example, a suction cup is provided between the first holding unit 25 and the second holding unit 26, and when the front wall portion 102 of a bag body 100 is bent by the first holding unit 25 and the second holding unit 26, the front wall portion 102 may be sucked by the suction cup. In this case, by moving the suction cup, the front wall portion 102 can be moved to open the bag body 100. In this way, it is possible to open a bag body 100 without blowing air into the mouth portion 101 of the bag body 100, and therefore, the above-described air blowing unit 12 may not be provided.

[0091] Further, in the embodiments and the modified examples described above, when the first holding unit 25 and the second holding unit 26 are pressed against the front wall portion 102 of a bag body 100, both the contact part 31 of the first holding unit 25 and the contact part 31 of the second holding unit 26 are moved in the Y direction (that is, the extension direction of the bag body 100); however, only one of the contact parts 31 of the first holding unit 25 and the second holding unit 26 may be moved in the Y direction. Similarly, when the third holding unit 27 and the fourth holding unit 28 are pressed against the back wall portion 103 of a bag body 100, only one of the contact parts 31 of the third holding unit 27 and the fourth holding unit 28 may be moved in the Y direction.

[0092]  Further, in the bag opening apparatus 10 of the second embodiment shown in Figs. 6 to 13, the receiving surface 51 of the receiving part 50 may have any structure capable of appropriately supporting the back wall portion 103 of a bag body 100. For example, one or more of suction holes may be formed in the receiving surface 51, and in a state in which the back wall portion 103 of a bag body 100 is in contact with the receiving surface 51 of the receiving part 50, the suction may be performed through the one or more of suction holes. In this case, the back wall portion 103 of a bag body 100 can be sucked by the receiving part 50, and the back wall portion 103 can be effectively prevented from deflecting when the front wall portion 102 of the bag body 100 is bent by the first holding unit 25 and the second holding unit 26.

[0093] Further, in the above-described embodiments and modified examples, a case where a bag body 100 is intermittently transferred with grippers 110 and the bag body 100 is opened by the bag opening apparatus 10 while the bag body 100 is stopped is described, but the bag opening apparatus 10 may open a bag body 100 which is in a moving state. For example, by configuring the bag opening apparatus 10 to be movable and by providing the bag opening apparatus 10 so as to follow a moving bag body 100 in a part of the transfer path of the bag body 100, it is possible for the bag opening apparatus 10 to open the bag body 100 without stopping the bag body 100. Therefore, bag opening apparatuses and bag opening methods according to the present invention can be applied not only to apparatuses adopting an intermittent transport system as described above but also to apparatuses which continuously transport a bag body 100 without intermittently stopping the bag body 100. Further, it is possible that, in an intermittent transfer type apparatus, a bag body 100 is opened by the bag opening apparatus 10 while the bag body 100 is intermittently moving.

[0094] The embodiments of the present invention include embodiments which each include a constituent element and/or a method other than the above-described constituent elements and/or methods. Also, embodiments in which some of the above-described constituent elements and/or methods are not included may also be included in the embodiments of the present invention. Further, embodiments which each include some constituent elements and/or methods included in a certain embodiment of the present invention and some constituent elements and/or methods included in another embodiment of the present invention may also be included in the embodiments of the present invention. Therefore, constituent elements and/or methods included in the embodiments and modified examples described above and embodiments of the present invention which are not described above may be combined with one another, and an embodiment based on such combination may also be included in the embodiments of the present invention. Further, the effects brought about by the present invention are not limited to the above-described effects, and particular effects depending on the specific configuration of each embodiment can be exerted. As described above, various additions, modifications and partial deletions may be made to each element described in the claims, the description, the abstract and the drawings without departing from the technical idea and gist of the present invention.

Claims

1. A bag opening apparatus (10) comprising a gap formation unit (11) which bends at least a front wall portion (102), of the front wall portion (102) and a back wall portion (103) that constitute a mouth portion (101) of a bag body (100), so as to form a gap between the front wall portion (102) and the back wall portion (103), wherein:

the gap formation unit (11) includes a first holding unit (25) and a first press drive member (23) which moves the first holding unit (25) between a position where the first holding unit (25) is separated from the front wall portion (102) and a position where the first holding unit (25) is pressed against the front wall portion (102),

the first holding unit (25) includes a contact part (31), a support part (32) which swingably supports the contact part (31), and an urging part (33) which urges the contact part (31) via the support part (32), and

when the first press drive member (23) presses the first holding unit (25) against the front wall portion (102), the contact part (31) is swung against urging force of the urging part (33) while the contact part (31) is in contact with the front wall portion (102) so as to bend the front wall portion (102).

2. The bag opening apparatus (10) as defined in claim 1, wherein:

the gap formation unit (11) further includes a second holding unit (27),

the first press drive member (23) moves not only the first holding unit (25) but also the second holding unit (27) between the position where the first holding unit (25) and the second holding unit (27) are separated from the front wall portion (102) and the position where the first holding unit (25) and the second holding unit (27) are pressed against the front wall portion (102), and

when the first press drive member (23) presses the first holding unit (25) and the second holding unit (27) against the front wall portion (102), the contact part (31) of the first holding unit (25) is swung so as to approach the second holding unit (27) while the contact part (31) of the first holding unit (25) is in contact with the front wall portion (102).

3. The bag opening apparatus (10) as defined in claim 2, wherein:

the second holding unit (27) includes a contact part (31), a support part (32) which swingably supports this contact part (31), and an urging part (33) which urges this contact part (31) via the support part (32), and

when the first press drive member (23) presses the first holding unit (25) and the second holding unit (27) against the front wall portion (102), the contact part (31) of the second holding unit (27) is swung against urging force of the urging part (33) of the second holding unit (27) so as to approach the contact part (31) of the first holding unit (25) while the contact part (31) of the second holding unit (27) is in contact with the front wall portion (102).

4. The bag opening apparatus (10) as defined in any one of claims 1 to 3, further comprising an air blowing unit (12) which ejects air toward the gap.

5. The bag opening apparatus (10) as defined in claim 3, wherein:

the gap formation unit (11) further includes: a third holding unit (27) and a fourth holding unit (28); and a second press drive member (24) which moves the third holding unit (27) and the fourth holding unit (28) between a position where the third holding unit (27) and the fourth holding unit (28) are separated from the back wall portion (103) and a position where the third holding unit (27) and the fourth holding unit (28) are pressed against the back wall portion (103), and

in a state where the contact part (31) of the first holding unit (25) and a contact part (31) of the third holding unit (27) are opposed to each other via the front and back wall portions (102, 103) and the contact part (31) of the second holding unit (27) and a contact part (31) of the fourth holding unit (28) are opposed to each other via the front and back wall portions (102, 103), the first press drive member (23) presses the first holding unit (25) and the second holding unit (27) against the front wall portion (102), and the second press drive member (24) presses the third holding unit (27) and the fourth holding unit (28) against the back wall portion (103).

6. The bag opening apparatus (10) as defined in any one of claims 1 to 4, wherein:

the gap formation unit (11) further includes a receiving part (50) which are disposed on a side of the back wall portion (103) and has a receiving surface (51) facing the back wall portion (103), and

the first press drive member (23) presses the first holding unit (25) against the front wall portion (102) in a state where the front wall portion (102) and the back wall portion (103) are sandwiched by the first holding unit (25) and the receiving surface (51).

7. The bag opening apparatus (10) as defined in claim 6, wherein the receiving part (50) includes a first elastic member (52) forming the receiving surface (51).

8. The bag opening apparatus (10) as defined in any one of claims 1 to 7, wherein:

the first holding unit (25) includes:

a first link (34) which is attached to the first press drive member (23) and swingably supports one side of the support part (32) of the first holding unit (25), and

a second link (35) which is attached to the first press drive member (23) so as to be capable of moving back and forth and swingably supports another side of the support part (32) of the first holding unit (25), and

when the first press drive member (23) presses the first holding unit (25) against the front wall potion, the urging part (33) of the first holding unit (25) urges the contact part (31) of the first holding unit (25), via the second link (35) and the support part (32) of the first holding unit (25), in a direction including a component of a direction opposing a direction in which the contact part (31) of the first holding unit (25) is swung.

9. The bag opening apparatus (10) as defined in any one of claims 1 to 8, wherein the contact part (31) includes a second elastic member.

10. The bag opening apparatus (10) as defined in any one of claims 1 to 9, further comprising a pair of grippers (110) which holds both side portions of the bag body (100),
wherein before or while the first press drive member (23) presses the first holding unit (25) against the front wall portion (102) to cause the contact part (31) of the first holding unit (25) to swing, at least one of the grippers (110) is moved in such a manner that a distance between the grippers (110) is reduced.

11. A bag opening method causing a bag opening apparatus (10) to bend at least a front wall portion (102), of the front wall portion (102) and a back wall portion (103) that constitute a mouth portion (101) of a bag body (100), so as to form a gap between the front wall portion (102) and the back wall portion (103), wherein:

the bag opening apparatus (10) includes a gap formation unit (11) having: a first holding unit (25); and a first press drive member (23) which moves the first holding unit (25) between a position where the first holding unit (25) is separated from the front wall portion (102) and a position where the first holding unit (25) is pressed against the front wall portion (102),

the first holding unit (25) includes a contact part (31), a support part (32) which swingably supports the contact part (31), and an urging part (33) which urges the contact part (31) via the support part (32), and

the bag opening method includes a step of bending the front wall portion (102) by causing the first press drive member (23) to press the first holding unit (25) against the front wall portion (102) in such a manner that the contact part (31) is swung against urging force of the urging part (33) while the contact part (31) is in contact with the front wall portion (102).

Drawing