Web forming device and forming method, and bag making machine for double bag

Abstract

This web forming device forms a double-folded double web comprising a first web and a second web. The web forming device comprises: a first tension adjustment mechanism that controls the tension of the first web being fed in the longitudinal direction; and a second tension adjustment mechanism that controls the tension of the second web being fed in the longitudinal direction independently of the first tension adjustment mechanism. The web forming device further comprises: a guide member located downstream of the first and second tension adjustment mechanisms and disposed to guide the first web and the second web downstream while overlapping the webs on each other; and a triangular plate located downstream of the guide member and disposed so as to fold in half the first web and the second web overlapped on each other.

Description

Web forming device and forming method, and double-layer bag making machine

[0001] The present application relates to a web forming apparatus and a web forming method for forming a folded double web used in making double-sided bags, such as double-gusset webs.The present application also relates to a bag making machine for sequentially producing double-sided bags.

[0002] Double-walled bags are widely known, as disclosed in, for example, Patent Documents 1 and 2. A double-walled bag includes at least two double-walled bodies facing each other. A storage space is formed between the two double-walled bodies. Each double-walled body is made up of an inner body portion and an outer body portion that are overlapped with each other.

[0003] Furthermore, the double-layered bags disclosed in Patent Documents 1 and 2 include a pair of double-layered gussets. The double-layered gusset also has a double structure and is made up of an outer gusset portion and an inner gusset portion that are folded in half and overlap each other.

[0004] Patent Document 1 discloses a bag making machine for sequentially producing such double-layered bags. The bag making machine includes a gusset forming device that forms a double-gusset web that becomes a double gusset. The gusset forming device unwinds an outer gusset web (for the outer gusset portion) and an inner gusset web (for the inner gusset portion) from their respective rolls and overlaps them. The gusset forming device then folds the overlapped outer gusset web and inner gusset web in half along fold lines extending in the length direction, thereby forming a double-gusset web.

[0005] In Patent Document 1, the overlapping outer gusset web and inner gusset web are folded in half using only one triangular plate. In this configuration, where two webs are folded using a single triangular plate, one of the two webs may sag or meander. Therefore, it is difficult to fold the outer gusset web and inner gusset web in a neat alignment. Poor finishing of the double gusset web naturally results in poor quality of the finished bag.

[0006] JP 2016-141427 A JP 2022-7011 A

[0007] The present application provides a web forming apparatus and a web forming method for forming a double-layered web that is folded in half with good finish, and a bag making machine including the web forming apparatus.

[0008] The present application provides a web forming device for manufacturing double-sided bags, which forms a folded double web comprising a first web and a second web, the web forming device comprising: a first tension adjustment mechanism that controls the tension of the first web being fed in the longitudinal direction; a second tension adjustment mechanism that controls the tension of the second web being fed in the longitudinal direction independently of the first tension adjustment mechanism; a guide member located downstream of the first and second tension adjustment mechanisms and arranged to guide the first web and the second web downstream while overlapping them; and a triangular plate located downstream of the guide member and arranged to fold the first web and the second web, which have been overlapped by the guide member, in half along a fold curve extending in the longitudinal direction.

[0009] The web forming device may be, for example, a gusset forming device for forming a double gusset web having an outer gusset web as the first web and an inner gusset web as the second web.

[0010] The first tension adjustment mechanism may further convert the feeding of the first web from continuous feeding to intermittent feeding, and the second tension adjustment mechanism may further convert the feeding of the second web from continuous feeding to intermittent feeding.

[0011] The first tension adjustment mechanism may be a first dancer mechanism. The second tension adjustment mechanism may be a second dancer mechanism. The first dancer mechanism may include a first dancer roller that engages with the first web to apply tension to the first web. The second dancer mechanism may include a second dancer roller that engages with the second web to apply tension to the second web.

[0012] The guide member may be, for example, a guide roller.

[0013] The web forming device may further include a temporary fastening device provided downstream of the triangular plate for temporarily fastening the first web and the second web to each other.

[0014] The present application also provides a bag making machine for sequentially manufacturing double-sided bags having a first double-sided body, a second double-sided body, and a double gusset. The bag making machine includes: an intermittent feeding device that intermittently feeds a first outer body web, a first inner body web, a second outer body web, and a second inner body web in the longitudinal direction; a pair of overlapping rollers that overlap the first outer body web, the first inner body web, the second inner body web, and the second outer body web in this order; a web forming device as the gusset web forming device that supplies the double gusset web so that when the first outer body web, the first inner body web, the second inner body web, and the second outer body web are overlapped at the position of the overlapping roller pair, the double gusset web is interposed between the first inner body web and the second inner body web and positioned in the longitudinal direction; and at least one heat sealing device that is provided downstream of the overlapping roller pair and heat-seals the first and second outer body webs, the first and second inner body webs, and the double gusset web with each intermittent feeding. and a cross-cutting device that is provided downstream of the heat-sealing device and that cross-cuts the first and second outer body webs, the first and second inner body webs, and the double gusset web in their width direction each time the bag is intermittently fed to form the double bag, wherein the first double body is formed from the first outer body web and the first inner body web, the second double body is formed from the second outer body web and the second inner body web, and the double gusset is formed from the double gusset web.

[0015] The bag making machine may further include a spout attachment device that is provided downstream of the overlapping roller pair and upstream of the heat-sealing device and that attaches spouts to the overlapping first outer body web and first inner body web with each intermittent feed. The spout attachment device may include: a plurality of guide rollers that temporarily separate the second outer body web, the second inner body web, and the double gusset web from the first outer body web and first inner body web to provide a temporary separation section; a temporary fastening unit that is provided in the temporary separation section and temporarily fastens the first outer body web and first inner body web to each other; a hole punching unit that is provided downstream of the temporary fastening unit in the temporary separation section and forms holes for the spouts in the first outer body web and first inner body web; and an attachment unit that is provided downstream of the hole punching unit in the temporary separation section and that inserts the spouts into the holes and attaches the inserted spouts to the first outer body web and first inner body web by heat sealing.

[0016] The web forming device may further include a hole punching device that forms holes for heat sealing in the double gusset web so that the first and second inner body webs are welded to each other through the holes by the heat sealing device.

[0017] The present application further provides a web forming method for forming a folded double web comprising a first web and a second web for manufacturing double-sided bags, the web forming method comprising: feeding the first web in its longitudinal direction; feeding the second web in its longitudinal direction; controlling the tension of the first web by a first tension adjustment mechanism; controlling the tension of the second web by a second tension adjustment mechanism independently from the control of the tension of the first web by the first tension adjustment mechanism; guiding the first web and the second web downstream while overlapping each other by a guide member located downstream of the first and second tension adjustment mechanisms; and folding the first web and the second web in half along a fold curve extending in the longitudinal direction while overlapping each other by a single triangular plate located downstream of the guide member, so as to interpose the folded first web between the folded second web.

[0018] The first web may include a first surface layer and a second surface layer having a melting point lower than that of the first surface layer, and the second web may have a melting point lower than that of the first surface layer. The first web and the second web may be folded in half along the fold line by the triangular plate so that the second surface layer contacts the second web.

[0019] The first web may be unwound from a first web roll and continuously fed in its longitudinal direction. The second web may be unwound from a second web roll and continuously fed in its longitudinal direction. The feeding of the first web may be converted from continuous feeding to intermittent feeding by the first tension adjustment mechanism. The feeding of the second web may be converted from continuous feeding to intermittent feeding by the second tension adjustment mechanism.

[0020] FIG. 1A shows an exemplary double-sided bag, and FIG. 1B is a partial cross-sectional view of the bag of FIG. 1A. FIG. 2A is a schematic side view of the upstream portion of an exemplary bag making machine, and FIG. 2B is a partial plan view of FIG. 2A. FIG. 3A is a schematic plan view of the midstream portion of an exemplary bag making machine, and FIG. 3B is a side view of FIG. 3A. FIGS. 4A and 4B show an exemplary point seal section, and FIG. 4C shows an exemplary spout attachment. FIG. 5A is a schematic plan view of the downstream portion of an exemplary bag making machine, and FIG. 5B is a side view of FIG. 5A. FIG. 6A shows an exemplary double-sided bag, and FIG. 6B is a partial cross-sectional view of overlapping webs, and FIGS. 6C and 6D show exemplary heat seal bars. FIG. 7A is a schematic plan view of an exemplary gusset forming device, and FIG. 7B is a partial side view of FIG. 7A. FIG. 8 is a detailed view of area Q of FIG. 7. Fig. 9A is a view as viewed from the arrow S1 in Fig. 7B, Fig. 9B is a view as viewed from the arrow S2 in Fig. 7B, Fig. 9C is a view as viewed from the arrow F in Fig. 7A, Fig. 9D is an enlarged view as viewed from the arrow J in Fig. 9C, and Fig. 9E is an enlarged view of region G in Fig. 7A. Fig. 10A is a schematic plan view of a gusset forming device according to the related art, and Fig. 10B is a cross-sectional view of a gusset web according to the related art formed by the gusset forming device of Fig. 10A.

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following is a description of the present application, by way of example only, with reference to the accompanying drawings.

[0022] Fig. 1A shows an exemplary double-walled bag 1. The double-walled bag 1 includes two double bodies 10 facing each other. As shown in the partial cross-sectional view of Fig. 1B, each double body 10 includes an outer body 100 and an inner body 101 that are stacked on top of each other. A storage space is formed between the two double bodies 10. The two inner bodies 101 face each other and are interposed between the two outer bodies 100.

[0023] The double-layered bag 1 further includes two double-layered gussets 11. The two double-layered gussets 11 form a pair, are folded between the two double-layered bodies 10, and extend along both side edges of the double-layered bodies 10. In other words, the double-layered gussets 11 in this example function as side gussets, and expand the storage space of the bag 1.

[0024] 1B, the double gusset 11 is made up of an outer gusset portion 110 and an inner gusset portion 111 that are overlapped with each other. The outer gusset portion 110 is located on the outside of the bag 1, and the inner gusset portion 111 is located on the inside of the bag 1. When the double gusset 11 is folded as shown in FIG. 1B, the outer gusset portion 110, which is folded in half, is interposed between the inner gusset portions 111, which are also folded in half.

[0025] The double bag 1 further includes a spout 12. The spout 12 is attached to one of the double bodies 10. Contents can be filled into or removed from the storage space through the spout 12.

[0026] To ensure airtightness, the double-layered bag 1 has a first seal 13 formed along both side edges of the bag 1 and a second seal 14 formed along the top and bottom edges of the bag 1. In the first seal 13 and the second seal 14, each inner body 101 is welded to the adjacent outer body 100 and inner gusset 111, and the outer gusset 110 and the inner gusset 111 are welded to each other. Furthermore, in the area of ​​the second seal 14 where the double gusset 11 is not present, the two inner body 101 are welded to each other.

[0027] As in Patent Document 2, the double-sided bag 1 further includes a third seal portion 15 that extends at an angle relative to both side edges and top and bottom edges of the bag 1. The third seal portion 15 extends obliquely from the edge of the folded edge (inner edge) of the double gusset 11 to the first seal portion 13. In the third seal portion 15, each inner body portion 101 is also welded to the adjacent outer body portion 100 and inner gusset portion 111, and the outer gusset portion 110 and the inner gusset portion 111 are welded to each other.

[0028] The opposing surfaces of the folded outer gusset portion 110 are not welded together.

[0029] An exemplary bag making machine for sequentially manufacturing the above exemplary double-layered bags 1 will now be described.

[0030] 2A is a schematic diagram illustrating the upstream portion of an exemplary bag making machine. Four raw webs 20', 21', 30', and 31' are installed. The raw web 20' is wound with the first outer body web 20 that will form the outer body portion 100 of one double body 10 (first double body) of the bag 1. The raw web 21' is wound with the first inner body web 21 that will form the inner body portion 101 of the first double body 10. The raw web 30' is wound with the second outer body web 30 that will form the outer body portion 100 of the other double body 10 (second double body) of the bag 1. The raw web 31' is wound with the second inner body web 31 that will form the inner body portion 101 of the second double body 10.

[0031] The outer body webs 20, 30 have, for example, a laminate structure. Each of the outer body webs 20, 30 includes a first surface layer, such as a base material layer, and a second surface layer, such as a sealant layer, having a lower melting point than the first surface layer. The inner body webs 21, 31 may be made of a material having a lower melting point than the base material layer (first surface layer) of the outer body webs 20, 30. Other properties (e.g., thickness) of these webs 20-31 are determined depending on the properties of the bag 1 to be manufactured (e.g., bag strength, etc.). This is similar to Patent Document 1.

[0032] The bag making machine includes a pair of overlapping rollers 50 for overlapping the webs 20-31. The webs 20-31 are continuously unwound and fed from their respective rolls 20'-31' in their longitudinal direction at a constant speed, and then guided to the pair of overlapping rollers 50 via a known accumulator and dancer roller (not shown). A dancer roller is provided for each web 20-31, and appropriately converts the feeding of the web 20-31 from continuous feeding to intermittent feeding. Therefore, the webs 20-31 are intermittently fed through the pair of overlapping rollers 50. For this purpose, the bag making machine includes an intermittent feeding device 53 (see FIGS. 5A and 5B) in its downstream portion for intermittently feeding the webs 20-31 in their longitudinal direction. Therefore, the webs 20-31 repeatedly feed and pause.

[0033] 2A , the webs 20-31 are guided to the overlapping roller pair 50 and overlapped with each other at the position of the overlapping roller pair 50. The overlapping order, from top to bottom, is the outer body web 20, the inner body web 21, the inner body web 31, and the outer body web 30. Here, the high-melting-point first surface layer (base layer) of the outer body web 20 faces upward Z1, and the low-melting-point second surface layer (sealant layer) faces downward Z2 and contacts the inner body web 21. The high-melting-point first surface layer of the outer body web 30 faces downward Z2, and the low-melting-point second surface layer faces upward Z1 and contacts the inner body web 31.

[0034] In order to overlap the webs 20-31 in the above-mentioned order and orientation, the original rolls 20', 30' are appropriately selected so that the webs 20, 30 are wound with their first surface layers facing inward or outward, and an appropriate number of guide members such as inclined plates that change the orientation of the webs 20, 30 are installed in appropriate locations.

[0035] The bag making machine further includes a web forming device 6 (FIG. 7A), which will be described in detail later. In this embodiment, the web forming device 6 is a gusset forming device that supplies a double-gusset web 4 (an example of a double-web folded in half) (FIGS. 2A and 2B) between the two inner body webs 21, 31 at a position upstream of the overlapping roller pair 50 so that when the webs 20-31 are overlapped with each other at the overlapping roller pair 50, the gusset web 4 is interposed between the inner body webs 21, 31 and is arranged in the longitudinal direction of the webs 20-31. Hereinafter, in this embodiment, the web forming device 6 will be referred to as a gusset forming device.

[0036] As shown by the two arrows R1 and R2 in Figure 2B, the two double-gusset webs 4 are fed from both sides of the width direction of the web 20-31, turned in the direction X1, and extend along both sides of the web 20-31. Therefore, downstream of the overlapping roller pair 50, the double-gusset web 4 is indexed in the longitudinal direction, i.e., in the direction X1, together with the web 20-31, by the indexing device 53.

[0037] This double gusset web 4 constitutes the double gusset 11 of the bag 1. As shown in FIG. 6B , the double gusset web 4 is composed of an outer gusset web 40 and an inner gusset web 41, which are folded in half and overlap each other. The outer gusset web 40 constitutes the outer gusset portion 111 of the double gusset 11. Like the outer body webs 20 and 30, the outer gusset web 40 has, for example, a laminate structure and includes a first surface layer (base material layer) and a second surface layer (sealant layer) having a melting point lower than that of the first surface layer. The inner gusset web 41 constitutes the inner gusset portion of the double gusset 11. Like the inner body webs 21 and 31, the inner gusset web 41 is made of a material having a melting point lower than that of the outer body webs 20 and 30 and the first surface layer (base material layer) of the outer gusset web 40. As shown in Figures 2B and 6B, the double gusset web 4 is fed so that its open edge 44 is aligned with the side edges of the webs 20-31 and its folded edge 43 is located on the inside.

[0038] 3A and 3B show the midstream portion of an exemplary bag making machine. Webs 20 and 21 constitute the first double-layered body 10 of the bag 1. Therefore, hereinafter, the overlapping webs 20 and 21 may be referred to as the (first) double-layered body web 2. Similarly, the overlapping webs 30 and 31 constitute the second double-layered body 10 of the bag 1, and therefore, hereinafter, the overlapping webs 30 and 31 may be referred to as the (second) double-layered body web 3.

[0039] The bag making machine further includes a spout attachment device 51 that is disposed downstream of the overlapping roller pair 50 and that attaches a spout 12 to the first double cylinder web 2 at each intermittent feed.

[0040] The spout attachment device 51 includes a plurality of guide rollers 510 for separating the second double cylinder web 3 and the double gusset web 4 from the first double web 2 and providing a temporary separation section in which the webs 2, 3, and 4 are temporarily separated. As shown in Figure 3B, in this example, the web 2 to which the spout 12 is attached is fed horizontally as is, and the webs 3 and 4 are temporarily separated in the downward direction Z2. The temporary separation section prevents the webs 3 and 4 from getting in the way when the spout 12 is attached to the web 2.

[0041] The spout attachment device 51 further includes a temporary fixing unit 511, a hole punching unit 512, and an attachment unit 513 in the temporary separation section.

[0042] 4A and 4B illustrate region T in Fig. 3A. The temporary fastening unit 511 temporarily fastens the webs 20 and 21 to each other by heat-sealing them at points each time the intermittent feeding is temporarily stopped, thereby forming point seal portions 16. This prevents the webs 20 and 21 from shifting relative to each other until the spout 12 is attached to the webs 20 and 21 as shown in Fig. 4C.

[0043] The point seal portion 16 is preferably located near the mounting position SA where the spout 12 is mounted. As shown in Fig. 4A, for example, the point seal portion 16 is preferably located near this position SA and within an area CS where a horizontal seal, described below, is applied. Alternatively, as shown in Fig. 4B, an annular point seal portion 16 may be formed along the periphery of the position SA. The position of the point seal portion 16 in Fig. 4B is the position that will be sealed by the mounting unit 513, described below.

[0044] In addition, as described below, the web 2-4 is slit along both side edges thereof, and waste resulting from the slitting is removed. The point seal portion 16 may be formed in the portion that is removed as waste. Unlike the examples shown in Figures 4A and 4B, two or more point seal portions may be provided for one position SA.

[0045] The punching unit 512 is disposed one pitch downstream of the intermittent feed from the temporary fastening unit 511. The punching unit 512 forms holes 17 ( FIG. 4C ) for the spouts 12 at positions SA in the web 2 (i.e., the webs 20, 21 temporarily fastened by the point seal unit 16) every time the intermittent feed stops. The punching unit 512 may form the holes 17 by punching the web 2 with a punch blade. Waste resulting from the formation of the holes 17 is sucked by a suction unit (not shown).

[0046] The attachment unit 513 is positioned downstream of the punching unit 512 by at least one pitch of intermittent feed and attaches the spout 12 to the web 2 each time the intermittent feed stops. As shown in FIG. 4C , a spout 12 with a flange 120 is used. The attachment unit 513 has an annular heat seal block (not shown) that corresponds to the shape of the flange 120. The attachment unit 513 inserts the spout 12 into the hole 17 from below and abuts the heat seal block against the web 20 from above to heat seal the flange 120 to the web 21. At this time, the low-melting second surface layer of the web 20 is in contact with the web 21, so the webs 20 and 21 are also heat-sealed to each other. Therefore, the spout 12, web 20, and web 21 are integrally welded.

[0047] The spout attachment device 51 further includes a spout detection unit 514 provided downstream of the attachment unit 513 within the temporary separation section. The spout detection unit 514 uses a sensor (not shown) (for example, an optical sensor) to determine whether the spout 12 is properly attached to the web 2. The spout detection unit 514 outputs a warning when the spout 12 is not properly attached.

[0048] These units 511 to 514 themselves are well known, and therefore detailed description thereof will be omitted here.

[0049] Thereafter, the webs 2-4 are overlapped with each other again by the downstream guide roller 510. The bag making machine includes a temporary fastening device 52 provided downstream of the spout attachment device 51. The temporary fastening device 52 temporarily fastens the webs 2-4 to each other by heat sealing, preventing the webs 2-4 from shifting position downstream. The temporary fastening position may be within an area where heat sealing will be applied thereafter (for example, area CS in FIG. 4A ).

[0050] 5A and 5B schematically show the downstream portion of an exemplary bag making machine. The bag making machine includes an intermittent feeding device 53 that intermittently feeds the web 2-4 in its longitudinal direction. The intermittent feeding device 53 includes at least one drive roller pair 530. The drive roller pair 530 is rotated intermittently by a servo motor while nipping the web 2-4, thereby intermittently feeding the web 2-4 in its longitudinal direction (direction X1). For example, multiple drive roller pairs 530 may be appropriately arranged.

[0051] The bag making machine further includes at least one heat sealing device 54, 56 that is provided downstream of the temporary fastening device 52 and heat-seals the webs 2-4 at each intermittent feed. In this example, a vertical sealing device 54 and a horizontal sealing device 56 are provided.

[0052] The vertical sealing device 54 heat-seals the web 2-4 in its longitudinal direction each time the intermittent feeding stops, forming first sealed portions 13 (see FIGS. 1A and 6A) along both side edges of the web 2-4. As described above, the webs 21, 31, and 41 are made of a low-melting-point material. Therefore, as is clear from the relative positions of the webs 2-4 in FIG. 6B, the four layers of the webs 20, 21, 40, and 41 are welded together, and the four layers of the webs 30, 31, 40, and 41 are welded together. Meanwhile, the two opposing surfaces of the folded outer gusset web 40 are the first outer layers with a high melting point, and therefore are not welded together. This also applies to the horizontal sealing described below.

[0053] The vertical sealing device 54 may heat-seal the webs 2-4 by pinching them with a heat seal bar. It is preferable to use a heat seal bar that is more than twice the length of the vertical dimension H (FIG. 6A) of the bag 1 (corresponding to the feed pitch of the intermittent feed). This allows the vertical sealing device 54 to heat-seal the same location at least twice.

[0054] The horizontal sealing device 56 heat-seals the web 2-4 in the width direction each time the intermittent feeding stops, forming a second sealed portion 14 (see FIGS. 1A and 6A) across the entire width of the web 2-4. At this time, in the region where the web 4 is not present, the inner body webs 21, 31 are welded together.

[0055] This exemplary horizontal sealing device 56 also forms the third sealed portion 15 (see FIGS. 1A and 6A). To this end, the horizontal sealing device 56 may use a generally K-shaped heat seal bar 560, as shown in FIG. 6C. Alternatively, the horizontal sealing device 56 may use a linear heat seal bar 561 for forming the second sealed portion 14 and a bifurcated heat seal bar 562 for forming the third sealed portion 15, as shown in FIG. 6D.

[0056] The root portions of the branches of the heat seal bar 560 and the heat seal bar 562 heat seal the central portion of the webs 2 and 3, and therefore the area where the web 4 is not present. This area has fewer web layers than the surrounding areas, which causes a step. This step may result in a seal failure. Therefore, to prevent a seal failure, an additional point seal may be applied to this area.

[0057] The bag making machine further includes a vertical cooling device 55 located downstream of the vertical sealing device 54 and a horizontal cooling device 57 located downstream of the horizontal sealing device 56. With each intermittent feed, the vertical cooling device 55 cools the first sealed portion 13, and the horizontal cooling device 57 cools the second and third sealed portions 14, 15. This cooling smooths the sealed surface, providing a well-finished sealed surface.

[0058] The bag making machine further includes a slitting device 58, located downstream of the heat sealing devices 54, 56 and the cooling devices 55, 57, that slits the web 2-4 along both side edges of the webs 2, 3. The slitting device 58 includes slitters disposed on both sides of the webs 2, 3. As the web 2-4 is fed, the slitters slit the web 2-4 along both side edges of the webs 2, 3. The waste generated during this process is wound and collected by known means. The new edges of the web 2-4 created by the slitting have high linearity. Therefore, both side edges (edges of the first sealed portion 13) of the manufactured bag 1 have high linearity.

[0059] The bag making machine further includes a cross-cutting device 59 disposed downstream of the slitting device 58, which cross-cuts the web 2-4 in its width direction each time the intermittent feed is stopped to form the double-layered bag 1. Specifically, the cross-cutting device 59 uses a cutter to cross-cut the web 2-4 in its width direction each time the intermittent feed is stopped, thereby obtaining the portion cut out from the web 2-4 as the double-layered bag 1 shown in FIGS. 1A and 6A. The cross-cut position is within the second seal portion 14 on the web 2-4, and more specifically, is the center line of the horizontal seal region CS, as indicated by the symbol CR in FIGS. 4A and 4B.

[0060] The bags 1 completed by cross-cutting are transported by a conveyor (not shown).

[0061] 7A-9E, the configuration of a gusset forming device 6 (an example of a web forming device) for forming and feeding a double-gusset web 4 (an example of a double-folded web) will be described. The illustrated bag making machine includes two gusset forming devices 6. One gusset forming device 6 feeds the web 4 from one side of the webs 20-31, as indicated by arrow R1 in FIG. 2B, while the other gusset forming device (shown in the accompanying drawings) feeds the web 4 from the other side of the webs 20-31, as indicated by arrow R2. The configurations of both gusset forming devices are symmetrical with respect to direction X1. Therefore, only the former gusset forming device 6 will be described, and a description of the latter gusset forming device will be omitted.

[0062] 7A and 7B, two raw webs 40' and 41' are installed. The raw web 40' is wound with an outer gusset web 40 (an example of a first web) that will form the outer gusset portion 110 of the double gusset 11 of the bag 1. The raw web 41' is wound with an inner gusset web 41 (an example of a second web) that will form the inner gusset portion 111.

[0063] The materials and configurations of the outer gusset web 40 and the inner gusset web 41 are as described above. In this example, the raw roll 40′ is formed by winding the laminated web 40 with its first surface layer having a high melting point facing outward and its second surface layer having a low melting point facing inward.

[0064] The gusset forming device 6 includes inclined plates 60 and 61 provided for the webs 40 and 41, respectively. Figures 9A and 9B are views taken along the arrows S1 and S2 in Figure 7A, respectively. The webs 40 and 41 are continuously unwound in their longitudinal directions at a constant speed from the raw webs 40' and 41', respectively, and fed to the inclined plates 60 and 61, where they are redirected from an upward direction Z1 to a horizontal direction Y1 by the inclined plates 60 and 61. The horizontal direction Y1 is a horizontal direction perpendicular to the feeding direction X1 of the webs 20-31 for the double drum 10. For this purpose, the bag making machine (gusset forming device 6) is equipped with first and second continuous feed devices 690, 691 (shown only in FIG. 8 ), which are provided in sections downstream of the inclined plates 60 / 61 and upstream of the first and second fixed rollers 621 / 631 with respect to the web 40 / 41, and continuously feed the web 40 / 41 in its longitudinal direction. Each of the first and second continuous feed devices 690, 691 includes, for example, a pair of drive rollers.

[0065] The gusset forming device 6 further includes a first tension adjustment mechanism 62 for the outer gusset web 40 provided downstream of the inclined plate 60, and a second tension adjustment mechanism 63 for the inner gusset web 41 provided downstream of the inclined plate 61. After the webs 40 and 41 are redirected in the horizontal direction Y1 by the inclined plates 60 and 61, respectively, they pass through the first and second tension adjustment mechanisms 62 and 63.

[0066] The first tension adjustment mechanism 62 converts the feeding of the web 40 from continuous feeding to intermittent feeding and appropriately controls the tension of the web 40 so that the web 40 is fed intermittently without slack or meandering. The second tension adjustment mechanism 63 converts the feeding of the web 41 from continuous feeding to intermittent feeding and appropriately controls the tension of the web 41 so that the web 41 is fed intermittently without slack or meandering. The tension control of the web 40 by the first tension adjustment mechanism 62 and the tension control of the web 41 by the second tension adjustment mechanism 63 are independent of each other.

[0067] The first tension adjustment mechanism 62 of the embodiment is a first dancer mechanism, and includes a first dancer roller 620 that engages with the web 40 to apply tension to the web 40, and two first fixed rollers 621 that are immovably arranged upstream and downstream of the first dancer roller 620 to guide the web 40 into engagement with the first dancer roller 620.

[0068] Furthermore, as shown only in FIG. 8 , which shows area Q in FIG. 7 in detail, the first tension adjustment mechanism 62 includes a first actuator 622 that supports the first dancer roller 620 so that it can move linearly (to the left and right in FIG. 8 ) and that urges the first dancer roller 620 against the web 40, a first sensor 623 that detects the position of the first dancer roller 620, and a first controller 624 (comprised of one or more processors) that controls the first continuous feed device 690.

[0069] The first dancer roller 620 moves left and right in FIG. 8 as the web 40 is intermittently fed by the intermittent feed device 53. At this time, the first sensor 623 detects the position of the first dancer roller 620. The first controller 624 then changes the feed speed of the web 40 by the first continuous feed device 690 (the rotational speed of the pair of drive rollers) based on the detection value of the first sensor 623. Through this series of control, the first controller 624 keeps the movement of the first dancer roller 620 within a predetermined range, and appropriately converts the feeding of the web 40 from continuous to intermittent while adjusting the tension of the web 40.

[0070] The second tension adjustment mechanism 63 of this embodiment is a second dancer mechanism of the same configuration as the first dancer mechanism, and as shown in Figure 8, is equipped with a second dancer roller 630, a second fixed roller 631, a second actuator 632, a second sensor 633, and a second controller 634 (consisting of one or more processors).

[0071] The second sensor 633 detects the position of the second dancer roller 630, which moves as the web 41 is intermittently fed by the intermittent feed device 53. The second controller 634 then changes the feed speed of the web 41 by the second continuous feed device 691 (for example, the rotation speed of the continuous feed roller pair) based on the detection value of the second sensor 633, thereby appropriately converting the feeding of the web 41 from continuous feeding to intermittent feeding while adjusting the tension of the web 41.

[0072] The first and second tension adjustment mechanisms 62, 63 are not limited to dancer mechanisms and may have other configurations. Alternatively, the first and second controllers 624, 634 may be configured as a single controller, and the single controller may control the tensions of the webs 40, 41 independently of each other.

[0073] As described above, the webs 40 and 41 are intermittently fed by the intermittent feeding device 53. In addition, the gusset forming device 6 may be equipped with an intermittent feeding device (not shown) (consisting of an appropriate number of drive roller pairs and a servo motor, configured similarly to the intermittent feeding device 53 of the bag making machine). The feed pitch of the intermittent feeding is indicated by the symbol P in FIG. 7A, which is set equal to the intermittent feeding pitch of the webs 20-31, and therefore corresponds to the vertical dimension H (FIG. 6A) of the bag 1. The timing of the intermittent feeding of both webs is also set equal to each other.

[0074] The gusset forming device 6 further includes a guide member 64 provided downstream of the tension adjustment mechanisms 62, 63, a triangular plate 65 provided immediately downstream of the guide member 64, a pair of crease rollers 66 disposed downstream of the triangular plate 65, a temporary fixing device 67 for the webs 40, 41 provided downstream of the pair of crease rollers 66, and a punching device 68 provided downstream of the temporary fixing device 67. The guide member 64 in this embodiment is a guide roller. These components 64-68 are disposed in the space between the two inner body webs 21, 31 before overlapping, upstream of the pair of overlapping rollers 50 ( FIG. 2A , etc.).

[0075] After passing through tension adjustment mechanisms 62 and 63, the webs 40 and 41 are fed in this order to a guide member 64 and a triangular plate 65. First, as the webs 40 and 41 are fed, the guide member 64 causes the webs 40 and 41 to overlap each other at the position of the guide member 64, and then guides the webs in this state to the triangular plate 65. At this time, the second surface layer of the outer gusset web 40, which has a low melting point, comes into contact with the inner gusset web 41.

[0076] Figure 9C is a view taken along line F in Figure 7A, and Figure 9D is an enlarged view taken along line J in Figure 9C. As shown in Figures 7A, 9C, and 9D, the webs 40 and 41, which have been overlapped by the guide member 64, are folded in half by the triangular plate 65 along the fold line 42 (Figure 9C) extending in the longitudinal direction as they are fed. As shown in Figure 9D, the folded outer gusset web 40 is interposed between the folded inner gusset web 41. The webs 40 and 41 then pass through the crease roller pair 66, which completes the folding and emphasizes the crease. The webs 40 and 41 are redirected from direction Y1 to direction X1 by passing through the guide member 64 and the triangular plate 65.

[0077] In this way, the double gusset web 4 is formed. The fold line 42 coincides with the center line in the width direction of the webs 40, 41. Note that reference numeral 43 in Figures 7A and 9D indicates a folded edge 43 of the double gusset web 4, which is formed at the position of the fold line 42. Reference numeral 44 indicates an open edge of the double gusset web 4. The two opposing surfaces of the folded web 40 become a first surface layer having a high melting point.

[0078] The gusset temporary fastening device 67 temporarily fastens the webs 40, 41 by heat sealing or ultrasonic sealing each time the webs are fed intermittently, thereby forming the point seal portion 18 (see FIG. 9E, an enlarged view of area G in FIG. 7A). This prevents the webs 40, 41 from shifting out of position. The position of the point seal portion 18 is, for example, within the horizontal seal area CS described above.

[0079] With each intermittent feed, the perforation device 68 forms a heat-sealing hole 19 (FIG. 9E) in the double gusset web 4. The hole 19 is located within the horizontal seal region CS. The hole 19 is formed, for example, on both sides of the cross-cut position CR.

[0080] The hole punching device 68 may form the holes 19 by punching the web 4 with a punch blade, for example. Like known hole punching devices, the hole punching device 68 is equipped with a suction unit (not shown) that sucks up waste generated when the holes 19 are formed. The hole punching device 68 also has a waste detection unit (not shown) that uses a sensor to detect whether waste has adhered to the web 4 without being sucked in, and outputs a warning when waste has adhered to the web 4.

[0081] Thereafter, when the webs 20-31 for the double cylinder 10 are overlapped with each other at the position of the overlapping roller pair 50, the double gusset web 4 is interposed between the inner cylinder webs 21, 31, as described above. At this time, as shown in FIG. 2B, the open edge 44 is aligned with the side edges of the webs 20-31, and the folded edge 43 is positioned on the inside, as described above.

[0082] In this example, when the horizontal sealing device 56 heat-seals the web 2-4 in its width direction, the point seal portion 18 is completely contained in the second seal portion 14, becomes one with it, and disappears, and the inner body webs 21, 31 are welded to each other through the holes 19.

[0083] When the inner gusset web and the outer gusset web are folded in half using one triangular plate as in Patent Document 1, one of them usually becomes loose or meanders, which can result in a poor finish of the double gusset web.

[0084] To address this problem, the gusset forming device 7 according to the related art shown in Fig. 10A includes triangular plates 70, 71 provided for each of the webs 40, 41, and a rotatable disk-shaped guide plate 72 provided downstream of the triangular plates 70, 71. The gusset forming device 7 folds the web 40 in half using the triangular plate 70 and the web 41 in half using the triangular plate 71, and then aligns the folded edges of the webs 40, 41 using the guide plate 72. However, the combination of the two triangular plates 70, 71 and the disk-shaped guide plate 72 can cause a gap 45 to form between the webs 40 and 41 as shown in Fig. 10B, which can adversely affect the finish of the double-layered bag 1.

[0085] As described above, the gusset forming device 6 of the present application folds the overlapping webs 40, 41 using a single triangular plate 65, but upstream thereof, first and second tension adjustment mechanisms 62, 63 independently control the tension of the webs 40, 41. Therefore, the problem of the prior art in that the webs 40, 41 become loose or meander when forming the double gusset web 4 does not occur. Furthermore, because the overlapping webs 40, 41 are folded in half together, the gap 45 of the related art described above does not occur.

[0086] Therefore, the gusset forming device 6 of the present application can form a double gusset web 4 with a better finish than the conventional or related art. Therefore, the bag making machine of the present application equipped with this gusset forming device 6 can provide a high-quality double bag 1.

[0087] The above-described double-layered bag 1 may be used as an inner bag of a bag-in-box, for example, as in Patent Document 2.

[0088] Instead of a laminate structure, the webs 20, 30, and 40 may be made of a mono-material film and a medium ink that inhibits heat sealing that is applied partially or entirely to the film. The webs 20-41 may be made of paper as a substrate and a resin that is partially or entirely coated on the paper. It will be obvious to those skilled in the art that the webs 20-41 are not limited to the above-mentioned exemplary configurations and materials, as long as they can be used to form the double-layered bag 1.

[0089] Alternatively, the webs 20 and 30 may be formed by slitting a wide web unwound from a single raw roll. The webs 21 and 31 may also be formed by slitting a wide web unwound from a single raw roll.

[0090] The main role of the overlapping roller pair 50 is to organize the conveyance lines of the webs 2, 3, and 4, not to convey the webs 2, 3, and 4. Therefore, the overlapping roller pair 50 does not necessarily need to nip the webs 2, 3, and 4, and the nipping force may be very weak or even zero. Conversely, if the nipping force is too strong, misalignment may occur between the layers in the laminate of the webs 2, 3, and 4, so care must be taken.

[0091] In the above embodiment, the double-layered web formed by the web forming device 6 is used as a double-gusseted web. In another embodiment, a double-layered web formed by a web forming device 6 having the same configuration as above is used as a double-layered cylinder web folded in half.

[0092] In this other embodiment, a double-layered bag without gussets is manufactured by forming a double-layered web folded in half using a web forming device 6 and then undergoing at least a heat sealing process and a cross-cut process using a bag making machine. This double-layered bag includes an outer body folded in half and an inner body folded in half and interposed between the outer body, with the outer body formed from a second web 41 of the double-layered web and the inner body formed from a first web 40 of the double-layered web. In this other embodiment, to achieve the heat sealing process, a material with a high melting point is used for the outer layer of the second web 41 and a material with a low melting point is used for the inner layer, and a material with a low melting point is used for the first web 40.

[0093] The bag making machine of the present application may manufacture double-sided bags having a zipper instead of or in addition to the spout 12. The bag making machine of the present application may manufacture double-sided bags with double gussets that function as top gussets and bottom gussets instead of the double gusset 11 that functions as a side gusset as exemplified above. In other words, bags may be made using the double gusset web 4 as a top gusset and / or a bottom gusset.

[0094] 1 Double bag 10 Double body 11 Double gusset 12 Spout 17 Spout hole 19 Heat sealing hole 2 First double body web 20 First outer body web 21 First inner body web 3 Second double body web 30 Second outer body web 31 Second inner body web 4 Double gusset web (an example of a double web folded in half) 40 Outer gusset web (an example of a first web) 41 Inner gusset web (an example of a second web) 42 Fold line 50 Pair of overlapping rollers 51 Spout mounting device 510 Guide roller 511 Temporary fastening unit 512 Hole punching unit 513 Mounting unit 53 Intermittent feed device 54 Vertical sealing device (an example of a heat sealing device) 56 Horizontal sealing device (an example of a heat sealing device) 59 Cross cut device 6 Web forming device (gusset forming device) 62 First tension adjustment mechanism (first dancer mechanism) 620: First dancer roller 63: Second tension adjustment mechanism (second dancer mechanism) 630: Second dancer roller 64: Guide member (guide roller) 65: Triangular plate 67: Temporary fixing device

Claims

1. A web forming device for producing double-sided bags, comprising a first tension adjustment mechanism that controls the tension of the first web being fed in the longitudinal direction; a second tension adjustment mechanism that controls the tension of the second web being fed in the longitudinal direction independently of the first tension adjustment mechanism; a guide member located downstream of the first and second tension adjustment mechanisms and arranged to guide the first and second webs downstream while overlapping them; and a triangular plate located downstream of the guide member and arranged to fold the first and second webs, which have been overlapped by the guide member, in half along a fold curve extending in the longitudinal direction.

2. The web forming apparatus according to claim 1, wherein the web forming apparatus is a gusset forming apparatus for forming a double gusset web having an outer gusset web as the first web and an inner gusset web as the second web as the double web.

3. The web forming apparatus of claim 1, wherein the first tension adjustment mechanism further converts the feeding of the first web from continuous feeding to intermittent feeding, and the second tension adjustment mechanism further converts the feeding of the second web from continuous feeding to intermittent feeding.

4. The web forming apparatus of claim 1, wherein the first tension adjustment mechanism is a first dancer mechanism; the second tension adjustment mechanism is a second dancer mechanism; the first dancer mechanism comprises a first dancer roller that engages with the first web to apply tension to the first web; and the second dancer mechanism comprises a second dancer roller that engages with the second web to apply tension to the second web.

5. The web forming apparatus according to claim 1, further comprising a temporary fastening device provided downstream of said triangular plate for temporarily fastening said first web and said second web to each other.

6. The web forming apparatus according to claim 1, wherein the guide member is a guide roller.

7. A bag making machine for sequentially manufacturing double layer bags having a first double body, a second double body, and a double gusset, comprising: an intermittent feed device for intermittently feeding a first outer body web, a first inner body web, a second outer body web, and a second inner body web in a longitudinal direction; a pair of overlapping rollers for overlapping the first outer body web, the first inner body web, the second inner body web, and the second outer body web in this order; and a web forming device according to claim 2, which supplies the double gusset web so that when the first outer body web, the first inner body web, the second inner body web, and the second outer body web are overlapped at the position of the overlapping roller pair, the double gusset web is interposed between the first inner body web and the second inner body web and positioned in the longitudinal direction; and at least one heat sealing device provided downstream of the overlapping roller pair for heat sealing the first and second outer body webs, the first and second inner body webs, and the double gusset web at each intermittent feed. a cross-cutting device that is provided downstream of the heat-sealing device and that cross-cuts the first and second outer body webs, the first and second inner body webs, and the double gusset web in their width direction at each intermittent feed to form the double bag, wherein the first double body is formed from the first outer body web and the first inner body web, the second double body is formed from the second outer body web and the second inner body web, and the double gusset is formed from the double gusset web.

8. The web further comprises a spout attachment device, which is provided downstream of the overlapping roller pair and upstream of the heat sealing device, and which attaches a spout to the overlapped first outer body web and first inner body web at each intermittent feed, the spout attachment device comprising: a plurality of guide rollers for temporarily separating the second outer body web, the second inner body web and the double gusset web from the first outer body web and the first inner body web to provide a temporary separation section; a temporary fastening unit provided in the temporary separation section for temporarily fastening the first outer body web and the first inner body web to each other; a hole punching unit provided downstream of the temporary separation section in the temporary separation section for forming holes for the spouts in the first outer body web and the first inner body web; and an attachment unit provided downstream of the hole punching unit in the temporary separation section for inserting the spout into the hole and attaching the inserted spout to the first outer body web and the first inner body web by heat sealing.

8. The bag making machine according to claim 7.

9. The bag making machine according to claim 7, wherein the web forming device further comprises a hole punching device that forms holes for heat sealing in the double gusset web so that the first and second inner body webs are welded to each other through the holes by the heat sealing device.

10. A web forming method for forming a folded double web comprising a first web and a second web for manufacturing a double bag, comprising: feeding the first web in its longitudinal direction; feeding the second web in its longitudinal direction; controlling the tension of the first web by a first tension adjustment mechanism; controlling the tension of the second web by a second tension adjustment mechanism independently of the tension of the first web controlled by the first tension adjustment mechanism; guiding the first web and the second web downstream while overlapping each other by a guide member located downstream of the first and second tension adjustment mechanisms; folding the first web and the second web in half along a fold curve extending in the longitudinal direction while overlapping each other by a single triangular plate located downstream of the guide member, and interposing the first web folded in half between the second web folded in half.

11. The web forming method described in claim 10, wherein the first web has a first surface layer and a second surface layer having a lower melting point than the first surface layer, the second web having a lower melting point than the first surface layer, and the first web and the second web are folded in half along the fold line by the triangular plate so that the second surface layer contacts the second web.

12. A web forming method as described in claim 10, wherein the first web is unwound from a first roll and continuously fed in its longitudinal direction, the second web is unwound from a second roll and continuously fed in its longitudinal direction, the feeding of the first web is converted from continuous to intermittent feeding by the first tension adjustment mechanism, and the feeding of the second web is converted from continuous to intermittent feeding by the second tension adjustment mechanism.

Images