Web forming device, web forming method, and bag making machine

Abstract

This web forming device comprises: a continuous feeding device that continuously feeds first and second webs; a first tension application mechanism that applies tension to the first web during continuous feeding; a second tension application mechanism that applies tension to the second web during continuous feeding independently of the first tension application mechanism; a guide member that is positioned downstream of the first and second tension application mechanisms and in a continuous feed section and is disposed so as to guide the first and second webs to the downstream while causing the webs to overlap each other; one triangular plate that is positioned downstream of the guide member and in the continuous feed section and is disposed so as to fold the overlapping first and second webs in half to form a multiple web; and a tension adjustment mechanism that controls the continuous feeding device to convert the feed of the multiple web from the continuous feed to the intermittent feed and adjust the tension a the double web.

Description

Web forming device, web forming method, and bag making machine

[0001] The present application relates to a web forming apparatus and a web forming method for forming a folded multi-layer web used in bag making, and also to a bag making machine including the web forming apparatus.

[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 well-finished folded multi-layer web, and a bag making machine including the web forming apparatus.

[0008] This application provides a web forming apparatus for forming a bag-making web folded in half, the web forming apparatus comprising: a continuous feeding device configured to continuously feed the first and second webs in their longitudinal direction; a first tensioning mechanism configured to apply tension to the first web during continuous feeding; a second tensioning mechanism configured to apply tension to the second web during continuous feeding independently of the first tensioning mechanism; a guide member located downstream of the first and second tensioning mechanisms and in a continuous feeding section where the first and second webs are continuously fed by the continuous feeding device, the guide member configured to guide the first and second webs downstream while overlapping each other; a triangular plate located downstream of the guide member and in the continuous feeding section, the triangular plate configured to fold the overlapped first and second webs in half along a fold line extending in the longitudinal direction to form the multiple web; and a tension adjustment mechanism configured to control the continuous feeding device to convert feeding of the multiple webs from continuous to intermittent and to adjust the tension of the multiple webs.

[0009] The continuous feed device may include a pair of drive rollers arranged downstream of the triangular plate for continuously feeding the multiple webs in the longitudinal direction thereof, and the tension adjustment mechanism may include a dancer roller arranged downstream of the pair of drive rollers for engaging with the multiple webs to apply tension to the multiple webs, an actuator for biasing the dancer roller, a sensor for detecting the position of the dancer roller, and a controller for changing the rotational speed of the pair of drive rollers based on the output of the sensor, thereby converting the feeding of the multiple webs from continuous to intermittent feeding and adjusting the tension of the multiple webs.

[0010] The first tension applying mechanism may include a first tension roller that engages with the first web but not the second web, and a first biasing member for biasing the first tension roller against the first web, and the second tension applying mechanism may include a second tension roller that engages with the second web but not the first web, and a second biasing member for biasing the second tension roller against the second web.

[0011] The web forming device may further include a temporary fastening device that is provided downstream of the triangular plate and that temporarily fastens the first web and the second web to each other.

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

[0013] The web forming device may be, for example, a gusset forming device for forming a multi-gusset web having an outer gusset web as the first web and an inner gusset web as the second web as the multi-web.

[0014] The present application also provides a bag making machine for sequentially producing multiple bags, the bag making machine comprising: an intermittent feeding device that intermittently feeds a first multi-cylinder web and a second multi-cylinder web in the longitudinal direction; a pair of overlapping rollers that overlap the first and second multi-cylinder webs; the web forming device that supplies the multi-gusset web so that when the first and second multi-cylinder webs are overlapped at the overlapping roller pair, the multi-gusset web is interposed between the first and second multi-cylinder webs and positioned in the longitudinal direction; a heat sealing device that is located downstream of the overlapping roller pair and heat-seals the first and second multi-cylinder webs and the multi-gusset web with each intermittent feeding; and a cross-cutting device that is located downstream of the heat-sealing device and cross-cuts the first and second multi-cylinder webs and the multi-gusset web in the width direction with each intermittent feeding to form the multiple bag.

[0015] The web forming device may further include a perforating device that forms holes for heat sealing in the multi-gusset web so that the first and second multi-gusset webs are welded to each other through the holes by the heat sealing device.

[0016] Further provided herein is a web forming method for forming a double-folded multi-layer web comprising a first web and a second web for bag making. The web forming method comprises: a continuous feeding device continuously feeding the first and second webs in their longitudinal directions; a first tensioning mechanism applying tension to the first web during continuous feeding; a second tensioning mechanism applying tension to the second web during continuous feeding independently of the application of tension to the first web by the first tensioning mechanism; a guide member guiding the first and second webs downstream while overlapping each other; and a triangular plate folding the first and second webs in half along a fold line extending in the longitudinal direction while overlapping each other, and interposing the folded first web between the folded second webs to form the multi-layered web; the guide member is located downstream of the first and second tensioning mechanisms and in a continuous feeding section where the first and second webs are continuously fed by the continuous feeding device; and the triangular plate is located downstream of the guide member and in the continuous feeding section; and the web forming method further comprises: A tension adjustment mechanism controls the continuous feed device to convert the feeding of the multiple webs from continuous to intermittent and adjust the tension of the multiple webs.

[0017] 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.

[0018] The multiple webs may be, for example, a double web consisting of only the first web and the second web.

[0019] 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 the upstream portion of an exemplary gusset forming device, and FIG. 7B is a partial side view of FIG. 7A. Fig. 8A is a schematic plan view of the downstream portion of the gusset forming device of Fig. 7A, and Fig. 8B is a partial side view of Fig. 8A. Fig. 9A is a view as viewed from the arrow S1 of Fig. 7B, Fig. 9B is a view as viewed from the arrow S2 of Fig. 7B, Fig. 9C is a view as viewed from the arrow F of Fig. 7A, Fig. 9D is an enlarged view as viewed from the arrow J of Fig. 9C, and Fig. 9E is an enlarged view of region G of Fig. 8A. 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.

[0020] 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.

[0021] FIG. 1A shows an exemplary bag 1. This bag is a multiple bag, more specifically, a double bag 1. The double bag 1 includes two double bodies (an example of a multiple body) 10 facing each other. As shown in the partial cross-sectional view of FIG. 1B, each double body 10 is composed of 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.

[0022] The double-walled bag 1 further includes two double gussets (an example of a multiple gusset) 11. The two double gussets 11 form a pair, are folded between the two double-walled bodies 10, and extend along both side edges of the double-walled bodies 10. In other words, the double gussets 11 in this example function as side gussets, and expand the storage space of the bag 1.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] The opposing surfaces of the folded outer gusset portion 110 are not welded together.

[0028] An exemplary bag making machine for sequentially manufacturing the above exemplary double-layered bags 1 will now be described.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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 multiple 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 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.

[0035] 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.

[0036] 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.

[0037] 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 element constituted by webs 20 and 21 may be referred to as a (first) double-layered body web 2 (an example of a first multi-layered body web). Similarly, webs 30 and 31 constitute the second double-layered body 10 of the bag 1. Therefore, hereinafter, the element constituted by webs 30 and 31 may be referred to as a (second) double-layered body web 3 (an example of a second multi-layered body web).

[0038] 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.

[0039] 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 cylinder 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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).

[0045] 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.

[0046] 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.

[0047] These units 511 to 514 themselves are well known, and therefore detailed description thereof will be omitted here.

[0048] 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 ).

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] The bags 1 completed by cross-cutting are transported by a conveyor (not shown).

[0060] 7A-9E, a gusset forming device 6 (an example of a web forming device) and a web forming method for forming and feeding a double-gusset web 4 (an example of a double-folded multiple 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 (not shown) 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.

[0061] 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.

[0062] 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.

[0063] The gusset forming device 6 includes a continuous feed device 60 that continuously feeds the webs 40, 41 (and the double gusset web 4 formed by the webs 40, 41) in the longitudinal direction. The feed device 60 is provided downstream of a triangular plate 65 (described later) and includes a (downstream) drive roller pair 600 that nip the double gusset web 4 (webs 40, 41) and continuously feeds it in the longitudinal direction.

[0064] In addition, the continuous feed device 60 may be provided with a first pair of upstream drive rollers 601a that are provided in a section where the webs 40, 41 are not overlapped with each other (i.e., upstream of the guide member 64 described below) and that nips the web 40 and continuously feeds it in its longitudinal direction, and a second pair of upstream drive rollers 601b that are provided in the same section and nips the web 41 and continuously feeds it in its longitudinal direction.

[0065] The feeding of the double gusset web 4 is converted from continuous feeding to intermittent feeding downstream of the drive roller pair 600, more specifically, by the up and down movement of a dancer roller 690 of a tension adjustment mechanism 69 (described later) located downstream of the drive roller pair 600. Therefore, the section upstream of the dancer roller 690 is a section in which the webs 40, 41 are continuously fed by the continuous feeding device 60. Hereinafter, this section will be referred to as the "continuous feeding section."

[0066] 7B , the gusset forming device 6 includes a guide roller 61a, a first tension applying mechanism 62a, and an inclined plate 63a provided for the web 40 in the continuous feed section. Similarly, the gusset forming device 6 includes a guide roller 61b, a second tension applying mechanism 62b, and an inclined plate 63b provided for the web 41 in the continuous feed section.

[0067] 9A and 9B are views taken along the arrows S1 and S2 in FIG. 7B, respectively. The webs 40 and 41 are continuously unwound in their longitudinal directions at a constant speed from the raw webs 40' and 41' by the continuous feed device 60, fed along guide rollers 61a and 61b, tensioning mechanisms 62a and 62b, and inclined plates 63a and 63b, and redirected from the upward direction Z1 to the horizontal direction Y1 by the inclined plates 63a and 63b. The horizontal direction Y1 is perpendicular to the feed direction X1 of the webs 20-31 for the double drum 10.

[0068] In this example, the first tension applying mechanism 62a is provided downstream of the guide roller 61a and upstream of the inclined plate 63a, and includes a first tension roller 620a that engages with the web 40 but not with the web 41, and a first biasing member (e.g., a cylinder or a spring) 621a that supports the first tension roller 620a and biases it toward the web 40 with a predetermined biasing force in the downward direction Z2 in Figures 7B and 9A. In this way, the first tension applying mechanism 62a applies tension to the web 40 that is being continuously fed at a constant speed, and adjusts the tension of the web 40 to be within a certain range.

[0069] Similarly, in this example, the second tension applying mechanism 62b is provided downstream of the guide roller 61b and upstream of the inclined plate 63b, and includes a second tension roller 620b that engages with the web 41 but not with the web 40, and a biasing member (e.g., a cylinder or a spring) 621b that supports the second tension roller 620b and biases it toward the web 41 with a predetermined biasing force in the downward direction Z2 in Figures 7B and 9B. In this way, the second tension applying mechanism 62b applies tension to the web 41 that is being continuously fed at a constant speed, and adjusts the tension of the web 41 to be within a certain range.

[0070] As is clear from FIGS. 7A and 7B, the application of tension to the web 40 by the first tensioning mechanism 62a and the application of tension to the web 41 by the second tensioning mechanism 62b are independent of each other.

[0071] The gusset forming device 6 further includes a guide member 64, a triangular plate 65, and a crease roller pair 66 in the continuous feed section, more specifically, upstream of the drive roller pair 600. The guide member 64 is a guide roller in this example, and is disposed downstream of the inclined plates 63a and 63b. The triangular plate 65 is disposed immediately downstream of the guide member 64. The crease roller pair 66 is disposed downstream of the triangular plate 65.

[0072] Therefore, the webs 40, 41 are continuously fed and tensioned independently by the first and second tensioning mechanisms 62a, 62b, and then pass through the guide member 64, the triangular plate 65, and the crease roller pair 66 in that order. First, the webs 40, 41 are overlapped with each other at the position of the guide member 64 as they are continuously fed, and are then guided in that 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.

[0073] 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 a fold line 42 (Figure 9C) extending in the longitudinal direction as they are continuously fed, with the folded outer gusset web 40 being interposed between the folded inner gusset web 41. The webs 40 and 41 then pass through a pair of crease rollers 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.

[0074] In this way, the double gusset web 4 is formed. The fold line 42 coincides with the center line of the webs 40, 41 in the width direction. Reference numeral 43 in FIGS. 7A and 9D denotes the folded edge 43 of the double gusset web 4, which is formed at the position of the fold line 42. Reference numeral 44 denotes the open edge of the double gusset web 4. The two opposing surfaces of the folded web 40 become the first surface layers with a high melting point. The double gusset web 4 is continuously fed in its longitudinal direction by the drive roller pair 600 of the continuous feed device described above.

[0075] 7A , the web forming device 6 further includes a tension adjustment mechanism 69. The tension adjustment mechanism 69 converts the feeding of the double gusset web 4 from continuous feeding to intermittent feeding and appropriately adjusts the tension of the double gusset web 4, thereby appropriately adjusting the tension of the webs 40, 41 collectively. As described above, the double gusset web 4 is interposed between the inner body webs 21, 31 and temporarily fastened to the inner body webs 21, 31 by the temporary fastening device 52 ( FIG. 5 ). Therefore, downstream of the tension adjustment mechanism 69, the double gusset web 4 is intermittently fed by the intermittent feeding device 53.

[0076] Fig. 8A is a plan view of the tension adjustment mechanism 69 and the portion downstream thereof, and Fig. 8B is a side view of a portion of Fig. 8A. As shown in Figs. 8A and 8B, the tension adjustment mechanism 69 includes a dancer roller 690 that engages with the double gusset web 4, and two fixed rollers 691 that are immovably provided upstream and downstream of the dancer roller 690 to guide the double gusset web 4 into engagement with the dancer roller 690.

[0077] Furthermore, as shown only in FIG. 8B , the tension adjustment mechanism 69 supports a dancer roller 690, is oriented so that the dancer roller 690 can move in the vertical directions Z1 and Z2 in FIG. 8B , and includes an actuator 692 for urging the dancer roller 690 against the double gusset web 4, a sensor 693 for detecting the position of the dancer roller 690, and a controller 694 (consisting of one or more processors) for controlling the pair of drive rollers 600 of the continuous feed device 60.

[0078] The double gusset web 4 is continuously fed by the continuous feed device 60 upstream of the dancer roller 690, and intermittently fed by the intermittent feed device 53 downstream of the dancer roller 690. The dancer roller 690 is disposed between the two feed devices 60, 53, and moves in the vertical directions Z1 and Z2 in FIG. 8B to accommodate variations in the feed path length of the double gusset web 4. At this time, a sensor 693 detects the position of the dancer roller 690. A controller 694 changes the feed speed of the double gusset web 4 by the drive roller pair 600 (the rotational speed of the drive roller pair 600) based on the output (detected value) of the sensor 693.

[0079] Through this series of controls, the controller 694 keeps the movement of the dancer roller 690 within a predetermined range, and appropriately converts from continuous feeding to intermittent feeding while adjusting the tension of the double gusset web 4 within an appropriate range. The controller 694 performs this series of controls by reading and executing a program stored in a storage medium (not shown).

[0080] As described above, in this embodiment, the tensions of the webs 40, 41 are independently adjusted within a certain range by the tension applying mechanisms 62a, 62b in the continuous feed section (more specifically, upstream of the drive roller pair 600). The webs 40, 41 then become the double gusset web 4, and are collectively adjusted to a substantially constant tension by the tension adjusting mechanism 69, and are converted to intermittent feed.

[0081] 8A , the gusset web forming device 6 further includes a gusset temporary fixing device 67 and a hole punching device 68. These devices 67 and 68 are provided downstream of the dancer roller 690, i.e., in the intermittent feed section where the double gusset web 4 is intermittently fed.

[0082] The gusset temporary fastening device 67 temporarily fastens the double gusset web 4 (and thus the webs 40, 41) by heat sealing or ultrasonic sealing each time the web is fed intermittently, thereby forming the point seal portion 18 (see FIG. 9E, an enlarged view of area G in FIG. 8A). This prevents the webs 40, 41 from shifting out of position. The position of the point seal portion 18 is, for example, within the transverse seal area CS described above.

[0083] 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.

[0084] The hole punching device 68 may form the holes 19 by punching the double gusset 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 double gusset web 4 without being sucked in, and outputs a warning when waste is adhered.

[0085] 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.

[0086] 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.

[0087] The above-mentioned components 64-69 of the gusset forming device are disposed in the space between the two inner cylinder webs 21, 31 before they are overlapped, upstream of the overlapping roller pair 50 (FIG. 2A, etc.).

[0088] However, when the inner gusset web and the outer gusset web are folded in half using a single 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.

[0089] 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.

[0090] 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 applying mechanisms 62a, 62b apply appropriate tensions independently to the webs 40, 41. This ensures that the webs 40, 41 are tightly attached to each other when the webs 40, 41 are folded in half together using the single triangular plate 65, and the gap 45 of the related art described above does not occur.

[0091] Another advantage of the gusset forming device 6 of the present invention is that the webs 40 and 41 pass through the guide member 64 and the triangular plate 65 in a continuous feed. When the webs 40 and 41 pass through the triangular plate 65, the webs 40 slide against the triangular plate 65. Unlike the embodiment, when the webs 40 and 41 pass through the triangular plate 65 in an intermittent feed, sudden tension fluctuations are also applied to the webs 40 and 41. This places a significant load on the webs when webs with low resistance to sliding (e.g., monomaterial webs such as polypropylene and polyethylene) are used. This embodiment, which does not experience such sudden tension fluctuations due to intermittent feed, is particularly effective when webs with low resistance to sliding are used. Even in such cases, the tension applying mechanisms 62a and 62b described above ensure that the webs 40 and 41 are folded in half by the triangular plate 65 while remaining in close contact with each other.

[0092] Furthermore, the tension applying mechanisms 62a, 62b and the continuous feeding described above work together to prevent the webs 40, 41 from sagging or meandering as occurs in the prior art.

[0093] Furthermore, the completed double gusset web 4 is converted to intermittent feed and the tension is adjusted appropriately by the tension adjustment mechanism 69. Therefore, the double gusset web 4 is prevented from slackening or meandering even downstream of the tension adjustment mechanism 69, and processing of the double gusset web 4 in the intermittent feed section (for example, processing by devices 67 and 68) can be performed with high precision.

[0094] 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.

[0095] The double gusset web 4 is essentially four layers, consisting of the webs 40 and 41 folded in half. After being converted to an intermittent feed, the four-layer double gusset web 4 is temporarily fastened to the webs 20, 21, 30, and 31 for the double cylinder 10 by a gusset temporary fastening device 67. This configuration further prevents the webs 40 and 41 from shifting relative to each other when the webs 40 and 41 are made of a monomaterial with low rigidity and high elasticity, such as polyethylene or polypropylene. This allows for more accurate insertion of side gussets, regardless of the material of the webs 40 and 41.

[0096] As described above, the webs 40, 41 are intermittently fed by the intermittent feeding device 53. In addition, the gusset forming device 6 may be provided with an intermittent feeding device (not shown) (an appropriate number of pairs of drive rollers configured similarly to the intermittent feeding device 53 of the bag making machine) downstream of the tension adjustment mechanism 69. The feed pitch of the intermittent feeding is indicated by the symbol P in FIG. 8A, 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 is also set equal to each other.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] In another embodiment, the web forming device 6 may be configured to form a triple gusset web (an example of a multiple gusset web) by using a third web (e.g., a middle gusset web) in addition to the first web 40 (outer gusset web) and the second web 41 (outer gusset web).

[0102] 7A and 7B , the web forming device 6 unwinds the third web from the original roll using a feed mechanism and continuous feed device 60, continuously feeds the third web in its longitudinal direction, and applies tension to the third web independently of the first and second webs 40, 41 using an additional (third) tension applying mechanism. The web forming device 6 then overlaps the first to third webs with each other at the guide member 64 and folds them in half along the fold line 42 using a triangular plate 65, thereby forming a triple-gusset web, which is then sent to a tension adjustment mechanism 69. Therefore, the bag making machine of this embodiment sequentially produces multi-layer bags having triple gussets (an example of multiple gussets).

[0103] The middle web of the triple gusset web is made of a material with a low melting point, and the outer webs can be made of either a material with a high melting point or a material with a low melting point, depending on which components are to be heat-sealed.

[0104] This embodiment also provides a neat finish to the triple-gusset web folded in half.

[0105] The three-layer structure allows a single web (film) to be made thinner. The overall flexibility of the bag is improved, making it sturdy and less likely to tear. Even with the same total amount of resin, the strength of the bag is improved. The strength of the triple gusset makes the bag more self-standing. By using a functional material for the additional web, the bag can be given that function.

[0106] Multiple webs are overlapped, and because this is done in a continuous conveying section, highly accurate overlapping is possible even when the number of webs is increased. Therefore, the web forming device 6 may be provided with a tension applying mechanism for each of the multiple webs, which applies tension to each web independently, overlaps the webs at the guide member 64, and folds the webs along the folding line 42 with the triangular plate 65 to form a multi-gusset web. In other words, the web forming device 6 may be configured to form not only double-gusset webs and triple-gusset webs, but also multi-gusset webs such as quadruple-gusset webs.

[0107] In the above embodiment, the multi-layer web formed by the web forming device 6 is used as a multi-gusset web. In another embodiment, the multi-layer web formed by the web forming device 6 having the same configuration as above is used as a double-folded multi-cylinder web.

[0108] In this alternative embodiment, a multi-layer bag without gussets is manufactured by forming a double-folded multi-body web using the web forming device 6 and then undergoing at least a heat sealing process and a cross-cut process using a bag making machine. This multi-layer bag is made of a plurality of body sections folded in half. To achieve the heat sealing process, a high-melting-point material is used for the outer layer of the outermost second web 41, and a low-melting-point material is used for the inner layer, while a low-melting-point material is used for the innermost first web 40 and a middle layer web (not shown).

[0109] In another embodiment, the bag making machine may be configured to form a first multi-cylinder web by stacking three or more webs instead of the first double-cylinder web 2, and to form a first multi-cylinder of the bag from the first multi-cylinder web. The bag making machine may further be configured to form a second multi-cylinder web by stacking three or more webs instead of the second double-cylinder web 3, and to form a second multi-cylinder of the bag from the second multi-cylinder web. This makes it possible to manufacture multi-layer bags with multiple gussets.

[0110] The bag making machine of the present application may manufacture bags having a zipper instead of or in addition to the spout 12. The bag making machine of the present application may manufacture bags with multiple gussets that function as top gussets and bottom gussets, instead of the multiple gussets 11 that function as side gussets as exemplified above. In other words, bags may be made using the multi-gusset web 4 as the top gusset and / or the bottom gusset.

[0111] 1 Double bag (an example of a multiple bag) 10 Double drum (an example of a multiple drum) 11 Double gusset (an example of a multiple gusset) 19 Hole for heat sealing 2 First double drum web (an example of a first multiple drum web) 20 First outer drum web 21 First inner drum web 3 Second double drum web (an example of a second multiple drum web) 30 Second outer drum web 31 Second inner drum web 4 Double gusset web (an example of a multiple 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 53 Intermittent feeding 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) 60 Continuous feeding device 600 Pair of driving rollers 62a First tension applying mechanism 620a First tension roller 621b First biasing member 62b Second tension applying mechanism 620b Second dancer roller 621b Second biasing member 64 Guide member (guide roller) 65 Triangular plate 67 Temporary fastening device 69 Tension adjusting mechanism 690 Dancer roller 692 Actuator 693 Sensor 694 Controller

Claims

1. A web forming apparatus for bag making, for forming a folded multi-layer web comprising a first web and a second web, A continuous feed device configured to continuously feed the first and second webs in their longitudinal direction, A first tensioning mechanism configured to apply tension to the first web during continuous feeding, A second tension-applying mechanism is configured to apply tension to the second web during continuous feeding, independently of the first tension-applying mechanism. A guide member is positioned downstream of the first and second tensioning mechanisms and in a continuous feed section in which the first and second webs are continuously fed by the continuous feed device, and is arranged to guide the first and second webs downstream while overlapping each other. A triangular plate is positioned downstream of the guide member and in the continuous feed section, and is arranged such that the first and second webs, which are superimposed on each other, are folded in half along a fold line extending in the longitudinal direction to form the multi-web, The system includes a tension adjustment mechanism configured to control the continuous feed device to convert the feeding of the multiple webs from continuous to intermittent and to adjust the tension of the multiple webs, The continuous feeding device is, A pair of drive rollers is provided, positioned downstream from the aforementioned triangular plate, to continuously feed the multi-web in its longitudinal direction. The tension adjustment mechanism is, A dancer roller is provided downstream of the drive roller pair and engages with the multi-web to apply tension to the multi-web, An actuator for biasing the aforementioned dancer roller, A sensor for detecting the position of the dancer roller, The system includes a controller that changes the rotational speed of the drive roller pair based on the output of the sensor, converts the feed of the multi-web from continuous feed to intermittent feed, and adjusts the tension of the multi-web. Web forming apparatus.

2. A web forming apparatus for bag making, for forming a folded multi-layer web comprising a first web and a second web, A continuous feed device configured to continuously feed the first and second webs in their longitudinal direction, A first tensioning mechanism configured to apply tension to the first web during continuous feeding, A second tension-applying mechanism is configured to apply tension to the second web during continuous feeding, independently of the first tension-applying mechanism. A guide member is positioned downstream of the first and second tensioning mechanisms and in a continuous feed section in which the first and second webs are continuously fed by the continuous feed device, and is arranged to guide the first and second webs downstream while overlapping each other. A triangular plate is positioned downstream of the guide member and in the continuous feed section, and is arranged such that the first and second webs, which are superimposed on each other, are folded in half along a fold line extending in the longitudinal direction to form the multi-web, A tension adjustment mechanism configured to control the continuous feed device to convert the feed of the multiple webs from continuous feed to intermittent feed and to adjust the tension of the multiple webs, The system includes a temporary fastening device provided downstream of the triangular plate for temporarily fastening the first web and the second web to each other. Web forming apparatus.

3. The first tensioning mechanism is, A first tension roller that engages with the first web but does not engage with the second web, The device comprises a first biasing member for biasing the first tension roller to the first web, The second tension-applying mechanism is, A second tension roller that engages with the second web and does not engage with the first web, The device comprises a second biasing member for biasing the second tension roller against the second web, A web forming apparatus according to claim 1 or claim 2.

4. The aforementioned guide member is a guide roller. A web forming apparatus according to claim 1 or claim 2.

5. A gusset forming apparatus for bag making, for forming a double-folded multi-gusset web comprising an outer gusset web and an inner gusset web, A continuous feed device configured to continuously feed the outer gusset web and the inner gusset web in their longitudinal direction, A first tensioning mechanism configured to apply tension to the outer gusset web during continuous feeding, A second tension-applying mechanism is configured to apply tension to the internal gusset web during continuous feeding, independently of the first tension-applying mechanism. A guide member is positioned downstream of the first and second tensioning mechanisms, and located in a continuous feeding section where the outer gusset web and the inner gusset web are continuously fed by the continuous feeding device, and is arranged to guide the outer gusset web and the inner gusset web downstream while overlapping each other. A triangular plate is positioned downstream of the guide member and in the continuous feed section, and is arranged such that the overlapping outer gusset web and the inner gusset web are folded in half along a fold line extending in the longitudinal direction to form the multi-gusset web, The system includes a tension adjustment mechanism configured to control the continuous feed device to convert the feeding of the multiple gusset web from continuous to intermittent and to adjust the tension of the multiple gusset web, Gusset forming apparatus.

6. A bag-making machine for sequentially manufacturing multi-layered bags, An intermittent feeding device for intermittently feeding the first multi-cylinder web and the second multi-cylinder web in their longitudinal direction, A pair of overlapping rollers for overlapping the first and second multi-layered webs, A gusset forming apparatus according to claim 5, wherein the multi-layer gusset web is supplied such that when the first and second multi-layer drum webs are superimposed on each other at the position of the overlapping roller pair, the multi-layer gusset web is interposed between the first multi-layer drum web and the second multi-layer drum web and arranged in the longitudinal direction, A heat sealing device is provided downstream of the aforementioned pair of overlapping rollers, and heat seals the first and second multi-layered drum webs and the multi-layered gusset webs with each intermittent feed, The system includes a cross-cutting device provided downstream of the heat sealing device, which, with each intermittent feed, cross-cuts the first and second multi-layered body webs and the multi-layered gusset webs in the width direction to form the multi-layered bag. Bag making machine.

7. The gusset forming apparatus further includes a hole-punching device that forms holes for heat sealing in the multi-layer gusset web so that the first and second multi-layer body webs are welded to each other through the holes by the heat sealing device. The bag-making machine according to claim 6.

8. A web forming method for forming a folded multi-layer web having a first web and a second web for bag making, The continuous feed device continuously feeds the first and second webs in their longitudinal direction. The first tension-applying mechanism applies tension to the first web during continuous feeding. The second tension-applying mechanism applies tension to the second web during continuous feeding, independently of the tension-applying of the first web by the first tension-applying mechanism. The guide member guides the first and second webs downstream while overlapping them, and The method involves using a single triangular plate to fold the first and second webs in half along a fold line extending in the longitudinal direction, with the folded first web interposed between the folded second webs, thereby forming the multi-layered web. The guide member is positioned downstream of the first and second tensioning mechanisms and in a continuous feed section in which the first and second webs are continuously fed by the continuous feed device. The triangular plate is positioned downstream of the guide member and within the continuous feed section. The aforementioned web forming method further includes, The tension adjustment mechanism controls the continuous feed device to convert the feeding of the multiple webs from continuous to intermittent, and adjusts the tension of the multiple webs, and The first web and the second web are temporarily fastened to each other downstream of the triangular plate. Web formation method.

9. The first web comprises a first surface layer and a second surface layer having a lower melting point than the first surface layer, and the second web has a lower melting point than the first surface layer. The first web and the second web are folded in half along the fold line by the triangular plate such that the second surface layer is in contact with the second web. The web forming method according to claim 8.

10. The aforementioned multiple web is a dual web consisting only of the first web and the second web. The web forming method according to claim 8.

11. A method for forming a gusset for bag making, comprising an outer gusset web and an inner gusset web, wherein The continuous feeding device continuously feeds the outer gusset web and the inner gusset web in their longitudinal direction. The first tension-applying mechanism applies tension to the outer gusset web during continuous feeding. The second tension-applying mechanism applies tension to the inner gusset web during continuous feeding, independently of the tension-applying of the outer gusset web by the first tension-applying mechanism. The guide member guides the outer gusset web and the inner gusset web downstream while overlapping each other, and The method involves using a single triangular plate to fold the outer gusset web and the inner gusset web in half along a fold line extending in the longitudinal direction, with the folded outer gusset web interposed between the folded inner gusset webs, thereby forming the multi-gusset web. The guide member is positioned downstream of the first and second tensioning mechanisms, and in a continuous feed section in which the outer gusset web and the inner gusset web are continuously fed by the continuous feed device. The triangular plate is positioned downstream of the guide member and within the continuous feed section. The gusset formation method further includes, The tension adjustment mechanism includes controlling the continuous feed device to convert the feed of the multiple gusset web from continuous feed to intermittent feed and adjusting the tension of the multiple gusset web. Method for forming a gusset.