Bag making method

Abstract

At least either of a horn or an anvil of the bag manufacturing method of the present application includes a plurality of protrusions protruding from a facing surface thereof. Also, two main body portions are clamped by the horn and the anvil, and a gusset portion folded between the main body portions is pressed. Two portions of the gusset portion are fused to each other by ultrasonic vibration of the horn during the clamping and pressing.

Description

TECHNICAL FIELD

[0001] The present application relates to a bag manufacturing method and a welding method that include welding two portions of a gusset portion folded between two main body portions to each other. BACKGROUND

[0002] A bag such as a plastic bag, a pouch, etc. includes two main body portions facing each other, for example. In order to expand the capacity of the bag, or in order to obtain self-supporting property of the bag, the bag includes a gusset portion folded between the main body portions.

[0003] The gusset portion is a side gusset portion, a bottom gusset portion, or a top gusset portion, for example. The gusset portion is divided into two portions by a bent edge thereof. The two portions are sometimes welded to each other at the end of the bag, for example, to prevent the bag from excessively expanding or to strengthen the self-supporting property of the bag. The reason for strengthening the self-supporting property of the bag is that, when the bag is placed on a placement surface, the two end edges of the gusset portion (the bottom gusset portion) constitute the contact portion of the bag with the placement surface, and, if the bag is filled with contents, the two end edges do not contact the placement surface as a straight line but as the outer edge of a region having a prescribed area.

[0004] Patent Document 1 discloses a method of ultrasonically welding the two portions of the gusset portion to each other. The method of Patent Document 1 is to bring a horn into contact with one of the main body portions, to bring an anvil into contact with the other main body portion, and to press the two main body portions and the gusset portion folded between the two main body portions by the horn and the anvil. Then, the two portions of the gusset portion are welded to each other by ultrasonic vibration of the horn.

[0005] In implementing such ultrasonic welding, the main body portions located between the horn / anvil and the gusset portion become a factor that reduces the transmission efficiency of the vibration energy from the horn to the welding site. Thus, there are cases where the two portions of the gusset portion are not tightly welded to each other.

[0006] An object of the present application is to provide a bag manufacturing method and a welding method that efficiently weld the two portions of the gusset portion.

[0007] PRIOR ART DOCUMENTS

[0008] PATENT DOCUMENTS

[0009] Patent Document 1: Japanese Patent No. 6537979 SUMMARY

[0010] According to an embodiment of the present application, there is provided a bag manufacturing method that includes:

[0011] The bag manufacturing method:

[0012] includes folding a web, and forming a continuous first main body portion, a continuous second main body portion, and a continuous gusset portion from the web, the gusset portion being folded between the first and second main body portions,

[0013] including clamping and pressing the first body portion, the second body portion, and the gusset portion folded between the first body portion and the second body portion by a welding horn and an anvil, the welding horn including a facing surface facing the anvil, the anvil including a facing surface facing the welding horn, at least either one of the welding horn and the anvil including a plurality of protrusions protruding from the facing surface thereof;

[0014] including ultrasonic welding the first portion and the second portion of the gusset portion to each other by the welding horn and the anvil; and

[0015] including cross-cutting the web along a width direction of the web across an ultrasonic welding region where the first portion and the second portion are ultrasonically welded to each other by the welding horn and the anvil, to manufacture a pouch.

[0016] The pouch manufacturing method can include manufacturing the pouch including the ultrasonic welding region having a length dimension in a pouch inner direction larger than a length dimension in a pouch outer direction.

[0017] The pouch manufacturing method can include manufacturing the pouch including the ultrasonic welding region having a trapezoidal shape narrowing toward a pouch outer direction.

[0018] The pouch manufacturing method can include manufacturing the pouch including the gusset portion as a bottom gusset portion.

[0019] The pouch manufacturing method can include manufacturing the pouch having traces of the plurality of protrusions generated when ultrasonically welding by the welding horn and the anvil.

[0020] Further, according to other embodiments of the present application, there is provided a welding method of ultrasonically welding a first portion and a second portion of a gusset portion folded between a first body portion and a second body portion to each other,

[0021] the welding method:

[0022] including clamping and pressing the first body portion, the second body portion, and the gusset portion folded between the first body portion and the second body portion by a welding horn and an anvil, the welding horn including a facing surface facing the anvil, the anvil including a facing surface facing the welding horn, at least either one of the welding horn and the anvil including a plurality of protrusions protruding from the facing surface thereof; and

[0023] ultrasonic vibrations of the horn during a period in which the first main body portion, the second main body portion, and the gusset portion are clamped and pressed by the horn and the anvil, the first portion and the second portion are fused to each other.

[0024] The plurality of protrusions can be pointed.

[0025] The fusion method can include:

[0026] The plurality of protrusions can be pointed.

[0027] The fusion method can include:

[0028] The plurality of protrusions can be pointed.

[0029] The plurality of protrusions can include flat tips.

[0030] The fusion method can include:

[0031] The plurality of protrusions can be pointed.

[0032] The first main body portion, the second main body portion, and the gusset portion can each be a laminate film including a base material layer including a base material and a sealant layer including a sealant having a lower melting point than the base material.

[0033] The fusion method can include:

[0034] The plurality of protrusions can be pointed.

[0035] The fusion method can include:

[0036] The plurality of protrusions can be pointed.

[0037] The first body portion, the second body portion, and the gusset portion can be separate components.

[0038] The plurality of protrusions can be provided on both the facing surfaces of the horn and the anvil. The protrusions of the horn and the protrusions of the anvil can be arranged offset from each other in a direction perpendicular to the facing direction of the horn and the anvil, with the leading ends of the protrusions of the horn and the protrusions of the anvil not facing each other. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1A is a schematic plan view of an example bag making machine, Figure 1B is a front view of Figure 1A is a side view of Figure 1C is a plan view of Figure 1A is a plan view of

[0040] Figure 2A is an enlarged plan view of area S of Figure 1A is a back view of Figure 2B is a plan view of Figure 2A is a plan view of Figure 2C is a plan view of Figure 2A is a plan view of an expansion roller in area T of

[0041] Figure 3 is a view showing an example bag of Figure 1A

[0042] Figure 4 is a cross-sectional view of a folded laminated film.

[0043] Figure 5A shows an example horn and anvil, Figure 5B shows an example arrangement of Figure 5A protrusions.

[0044] Figures 6A-6C shows an example ultrasonic welding.

[0045] Figure 7A shows another example horn and anvil, Figure 7B shows another example arrangement of Figure 7A protrusions.

[0046] Figure 8A shows another example horn and anvil, Figure 8B shows a positional relationship between the leading ends of the horn protrusions and the anvil protrusions.

[0047] Figure 9A , Figure 9B shows another example ultrasonic welding.

[0048] Figure 10A ,​Figure 10B indicates other example protrusions, Figure 10C Figure 10D indicates other example arrangements of protrusions.

[0049] Figures 11A-11C indicates other example ultrasonic welds in the bag.

[0050] Figure 12A is a plan view of the illustrated bag, Figure 12B Figure 12A is an enlarged view of area P of Figure 12C Figure 12B is a Q-Q line sectional view of Figure 12D Figure 12B is an R-R line sectional view of

[0051] Figure 13A indicates example ultrasonic weld areas in the bag, Figure 13B indicates example ultrasonic weld areas in the patch.

[0052] Figure 14A Figure 14B indicates further example ultrasonic weld areas in the bag.

[0053] [Explanation of Symbols]

[0054] 1: patch

[0055] 10: bag

[0056] 11, 12: main body portion

[0057] 13: gusset portion

[0058] 131, 132: gusset portion portions

[0059] 15: ultrasonic weld area

[0060] 30: horn

[0061] 300: facing surface

[0062] 301: protrusion

[0063] 31: anvil

[0064] 310: facing surface

[0065] 311: protrusion DETAILED DESCRIPTION

[0066] Hereinafter, embodiments of the present application will be described with reference to the drawings.

[0067] An example bag-making machine is shown in Figures 1A-1C Figure 1A ​​​​​​The material sheet (web) 1 is manufactured sequentially by a bag-making machine. The web 1 is continuously rolled out at a constant speed from the original sheet 1' along its length direction (its continuous direction), and folded in half by a first folding device 50. The first folding device 50 includes a triangular plate 500 and a pair of connecting rollers 501. The web 1 is folded in half along its long side centerline during transport, passing through the triangular plate 500 and the connecting rollers 501. Figure 1A The symbol 100 represents the folded edge produced by folding sheet 1 in half. Figure 1A Symbols 101 and 102 represent the two side edges of sheet 1 that are aligned with each other by folding sheet 1 in half.

[0068] Next, the folded sheet 1 is appropriately switched from continuous to intermittent feeding by a tension adjustment device 51 including tension adjustment rollers. Furthermore, a conveying device 52 including a pair of conveying rollers is provided in the downstream section of the bag-making machine, intermittently conveying the sheet 1 along its length. The conveying direction of the sheet 1 is indicated by the symbol X1.

[0069] Next, the sheet 1 is further folded by the second folding device 53, and two continuous main body parts 11 and 12 and a continuous corner support part 13 folded between these main body parts 11 and 12 are formed by the sheet 1.

[0070] The second folding device 53 includes a pair of expanding rollers 532 disposed downstream of a pair of guide rollers 530 and upstream of a pair of guide rollers 531. Figure 1B The sheet 1 is expanded by the expansion roller 532 in the interval between the guide roller 530 and the guide roller 531, and a space is set between the two layers of the sheet 1.

[0071] like Figure 2A , Figure 2B As shown, the second folding device 53 further includes a first forming plate 533 disposed downstream of the expansion roller 532, and a second forming plate 534 disposed downstream of the first forming plate 533.

[0072] The first forming plate 533 has a trapezoidal shape. The first forming plate 533 is disposed within the space formed by the expansion roller 532 such that it abuts against the portion of the sheet 1 including the bent edge 100 from the inside of the sheet 1. The first forming plate 533 is oriented in a manner that narrows towards the downstream.

[0073] The second forming plate 534 has a triangular shape. The second forming plate 534 is arranged to abut against the portion including the bent edge 100 from the outside. The second forming plate 534 narrows towards the downstream and towards the sheet 1, with one vertex 5340 (…). Figure 2B It becomes the downstream end of the second forming plate 534 and enters the sheet 1, approaching the guide roller 531, and abutting against the bending edge 100 of the sheet 1.

[0074] As sheet 1 is conveyed, the portion including the bent edge 100 is guided to the second forming plate 534 in an expanded state by the first forming plate 533, and then folded back in the opposite direction along the bent edge 100 in such a way that it enters between the two layers of sheet 1 through the second forming plate 534. Then, in the stated state, sheet 1 passes between a pair of guide rollers 531.

[0075] Thus, the portion including the bent edge 100 is folded between the two layers of the sheet 1, resulting in a continuous gusseted portion 13, and the two layers of the sheet 1 become two continuous main body portions 11 and 12. The bent edge 100 becomes the inner edge of the gusseted portion 13. The gusseted portion 13 is divided into two parts 131 and 132 by its inner edge 100 (see reference). Figure 4 ). Figure 2A Symbols 103 and 104 represent the outer edges of the gusset 13, which are also the boundary edges between the gusset 13 and the main body 11 and the main body 12. Hereinafter, the sheet 1 will be conveyed in a folded state as described.

[0076] Furthermore, the dimension by which the vertex 5340 of the second forming plate 534 enters the sheet 1 is the folding dimension of the corner brace 13. Figure 2C Will Figure 2A The expansion roller 532 in region T is shown in magnification. For example... Figure 2C As shown, each expansion roller 532 may include an R-shaped end 5320. Furthermore, the end 5320 may be located on the folded-in side of the sheet 1, contacting the inner surface of the sheet 1, thereby preventing damage to the sheet 1.

[0077] like Figure 1A , Figure 1B As shown, the continuous strip-shaped component 2 ( Figure 1A The material sheet 1 can be inserted between the two layers (i.e., the main body 11 and the main body 12) through the space ensured by the expansion roller 532. The strip member 2 in this embodiment can be a component that allows the bag 10 to be repeatedly opened and closed; specifically, it is a zipper comprising male and female materials that can be detachably fitted together. The zipper 2 is guided by the guide roller 54 to change direction while the male and female materials are fitted together, and is inserted between the main body 11 and the main body 12.

[0078] After the zipper 2 is inserted between the main body 11 and the main body 12, it can be irradiated with a laser device (not shown) and fused to the main body 11 and the main body 12. Therefore, the male material can be laser-fused to the inner surface of the main body 11 / 12, and the female material can be laser-fused to the inner surface of the main body 12 / 11. The laser device used for welding can be, for example, the laser device disclosed in Japanese Patent Application Publication No. 2017-47622. A heat sealing method can also be used instead of this laser method.

[0079] If the structure of the bag 10 becomes complicated, the process of assembling or forming additional components such as the belt member, the gusset, the bag opening, and the like is increased. As a result, the entire bag-making process also becomes complicated, and there is a concern that the bag-making speed will decrease. In order to appropriately increase the speed, it is important to seek a balance and avoid a particular process from becoming a bottleneck. For example, in the case of bag-making including a fusion process of the zipper 2 in the heat-seal method, if the fusion of the zipper 2 in the heat-seal method becomes a bottleneck, the fusion of the zipper 2 is performed in the laser method as in the present embodiment, and the bag-making speed is increased.

[0080] After the body portion 11, the body portion 12, and the gusset 13 are formed, the web 1 is conveyed once every time, and the web 1 is heat-sealed once along the width direction of the web 1 by the heat-sealing device 55. Thereby, the heat-sealed region 14 (hereinafter, referred to as a heat-sealed region) is generated on the web 1 at an interval corresponding to the width of the bag 10. Figure 1A The illustration is omitted in the middle, and reference is made to Figure 3 ) (hereinafter, referred to as a heat-sealed region). The heat-sealing device 55 can include a plurality of sealing units 550. In the embodiment, three sealing units 550 are provided, each including a pair of heat-sealing bars that are heated.

[0081] The number of the sealing units 550 can be determined in accordance with the bag-making speed and the like. The plurality of sealing units 550 can heat-seal the same portion sequentially, and can provide high-quality heat-sealing at high speed, or can heat-seal different portions.

[0082] As shown in Figure 4 , the web 1 of the embodiment is a laminate film including a base material layer 16 including a base material, and a sealant layer 17 including a sealant having a lower melting point than the base material. The base material can be, for example, nylon, polyethylene terephthalate (PET), or the like. The sealant can be, for example, polyethylene, polypropylene, or the like. The first surface of the web 1 is formed by the base material layer 16, and the second surface of the web 1 is formed by the sealant layer 17.

[0083] In a manner in which the outer surface of the web 1 (that is, the body portion 11, the body portion 12, and the gusset 13) is formed by the base material layer 16, and the inner surface of the web 1 (that is, the body portion 11, the body portion 12, and the gusset 13) is formed by the sealant layer 17, the web 1 is folded by the folding device 50 and the folding device 53. Then, heat-sealing is performed using the fusion of the sealant of the sealant layer 17.

[0084] Therefore, the heat-sealing device 55 heat-seals the main body portion 11 and the main body portion 12 to each other at regions thereof not facing the gusset portion 13, heat-seals the main body portion 11 and the gusset portion 13 (portion 131) to each other, and heat-seals the main body portion 12 and the gusset portion 13 (portion 132) to each other. On the other hand, the portions 131 and 132 of the gusset portion 13 are not heat-sealed to each other by the heat-sealing device 55 because their outer surfaces (facing surfaces) are formed by the base material layer 16.

[0085] The portions 131 and 132 are ultrasonically welded to each other once every time the web 1 is intermittently conveyed by the ultrasonic welding device 3. Thus, the ultrasonically welded regions 15 (hereinafter, ultrasonic welding regions) are produced on the web 1 at intervals corresponding to the width of the bag 10. Figure 1A The illustration of the intermediate stage is omitted, and reference is made to Figure 3

[0086] In the embodiment, the ultrasonic welding device 3 is disposed downstream of both of the sealing units 550 and upstream of one of the sealing units 550. The web 1 is heat-sealed twice at the same position by the two sealing units 550 upstream of the ultrasonic welding device 3, thereby softening the main body portion 11, the main body portion 12, and the gusset portion 13. The ultrasonic welding device 3 ultrasonically welds the main body portion 11, the main body portion 12, and the gusset portion 13 in a state of being lightly adhered by the softening. The ultrasonic welding device 3 and the welding method using the ultrasonic welding device 3 will be described in detail below.

[0087] The relative positional relationship between the ultrasonic welding device 3 and the heat-sealing device 55 (the sealing units 550) is arbitrary and can be appropriately determined in accordance with the material of the web 1 (the bag 10) or the purpose of welding, and the like. Also, the order of ultrasonic welding and heat-sealing can be appropriately determined in accordance with the material of the web 1 (the bag 10) or the purpose of welding, and the like.

[0088] After the heat-sealing and the ultrasonic welding, the web 1 and the slide fastener 2 are cross-cut once every time the web 1 is intermittently conveyed by the cross-cutting device 56 including a cutter, a receiving table, and the like, across the ultrasonic welding regions 15 at the position of the heat-sealed regions 14 in the width direction of the web 1. Thus, the bags 10 are sequentially manufactured.

[0089] Figure 3 is an enlarged view of the bag 10 of Figure 1A The bag 10 is repeatedly opened and closed by the slide fastener 2. The main body portion 11, the main body portion 12, and the gusset portion 13 are integrally formed from one piece of sheet material cut from the web 1. The opening of the bag 10 is defined by the edges 101 and 102. The gusset portion 13 functions as a bottom gusset portion. The regions 14 and 15 are divided into two portions by the cross-cutting and thus are located on both sides of the bag 10. ​

[0090] The ultrasonic welding device 3 and the method of ultrasonically welding the portions 131 and 132 of the corner brace 13 together using the ultrasonic welding device 3 will be described below.

[0091] like Figure 1B As shown, the ultrasonic welding apparatus 3 includes a welding head 30 and an anvil 31 arranged facing each other. The ultrasonic welding apparatus 3 further includes a driving device 32, which is configured to bring the welding head 30 closer to and further away from the anvil 31 and to cause the welding head 30 to vibrate ultrasonically. The welding head 30 and the anvil 31 face each other vertically across the intermittently conveyed sheet 1. Specifically, the welding head 30 and the anvil 31 face each other across the main body 11, the main body 12, and the corner support 13 folded between them.

[0092] The welding head 30 is brought close to the anvil 31 by the drive device 32, and the main body 11, main body 12, and corner bracket 13 are clamped and pressurized by the welding head 30 and the anvil 31. During the clamping and pressurization, the welding head 30 is vibrated at high frequency by the drive device 32. The energy of the ultrasonic vibration is transferred to the part to be welded (hereinafter referred to as the target part), and is converted into frictional heat at the target part. Then, the temperature rise caused by the frictional heat causes the components to be welded to each other at the target part. Specifically, when the corner bracket 13 is made of a single material such as polyethylene, the opposing surfaces of parts 131 and 132 are welded to each other. On the other hand, when the opposing surfaces of parts 131 and 132 of the corner bracket 13 include a laminate film of a substrate layer, the protrusion 311 of the anvil 31 and / or the protrusion 301 of the welding head 30 (see below) are used to weld the components together. Figure 5A , Figure 7A , Figure 8A (etc.) damage the substrate layer, causing the sealant layer of the laminate to melt out, thereby substantially fusing the opposing surfaces of portions 131 and 132 together.

[0093] The conditions for ultrasonic welding, including frequency, amplitude, vibration time, and applied pressure, can be appropriately selected based on the raw materials of the parts 131 and 132 to be welded, the required welding strength, etc.

[0094] like Figure 5A As shown, the welding head 30 includes a flat facing surface 300 facing the anvil 31. The anvil 31 includes a flat facing surface 310 facing the welding head 30 and a plurality of protrusions 311 protruding from the facing surface 310.

[0095] Protrusion 311 can be pointed. For example... Figure 5B As shown in the plan view, protrusions 311 can be arranged in a two-dimensional manner.

[0096] like Figure 6A , Figure 6BAs shown, when the main body 11, main body 12, and corner brace 13 are clamped and pressurized using the welding head 30 and anvil 31, the protrusion 311 penetrates at least the outer substrate layer 16 of the sheet material 1 and penetrates into the inner sealant layer 17. More specifically, the protrusion 311 penetrates portions 131 and 132 of the main body 12 and corner brace 13, piercing into the main body 11, main body 12, and portions 131 and 132, until reaching the opposite side of the main body 11. Then, in this state, the welding head 30 is subjected to ultrasonic vibration. Through the ultrasonic vibration, as... Figure 6C As shown, parts 131 and 132 are ultrasonically welded together.

[0097] Because the protrusion 311 enters the stacked portion including the main body 11, the main body 12, and the corner brace 13, the distance between the welding head 30 and the anvil 31 is shortened, thus shortening the distance between the welding head 30 / anvil 31 and the target area. As a result, vibration energy can be efficiently transmitted to the target area, causing the target area to heat up in a short time. Therefore, the efficiency of ultrasonic welding is improved by the protrusion 311.

[0098] Prior to ultrasonic welding, as described above, heat sealing using sealing unit 550 softens sheet 1 (its substrate layer 16). This facilitates the insertion of protrusion 311 into sheet 1, specifically making puncture easier.

[0099] As in the embodiment where a laminated film is used, the protrusions 311 penetrate the substrate layer 16, thus the sealant in the sealant layer 17 melts due to the ultrasonic vibration of the welding head 30, flowing into and filling the through-holes in the substrate layer 16. Figure 6C As shown, a filling portion 18 generates sealant. Through the filling portion 18, the main body portion 11, the main body portion 12, and portions 131 and 132 are integrally fused together, thereby improving the fusion strength of the ultrasonic welding area 15.

[0100] exist Figures 1A-1C In the bag making process, after ultrasonic welding, the downstream sealing unit 550 performs heat sealing again in the heat-sealing area 14 containing the ultrasonic welding area 15. At this time, the heat sealing of the sealant layers 17 is completed. Furthermore, the sealant that seeps out of the ultrasonic welding area 15, i.e., the sealant filling part 18, is further heated, so that although the marks of the protrusion 311 remain in the material sheet 1, i.e., the bag 10, a smooth and high-quality sealing surface can be achieved.

[0101] like Figure 7A , Figure 7B As shown, multiple protrusions 301 can be arranged in two dimensions, protruding from the opposing surface 300 of the welding head 30 rather than the opposing surface 310 of the anvil 31. This also allows the aforementioned effect to be achieved.

[0102] As shown in Figure 8A , Figure 8B , both the horn 30 and the anvil 31 can include protrusions 301, 311. Here, as shown in Figure 8B , the protrusions 301 of the horn 30 and the protrusions 311 of the anvil 31 are arranged offset from each other in a direction orthogonal to the facing direction of the same, so as to avoid the tips of the same facing each other.

[0103] Also, as shown in Figure 9A , Figure 9B , when the body portion 11, the body portion 12, and the gusset portion 13 are clamped and pressed using the horn 30 and the anvil 31, the protrusions 301 / 311 penetrate the body portion 11 / 12, the portions 131, 132 of the gusset portion 13, and puncture the body portion 11, the body portion 12, and the portions 131, 132, until reaching the body portion 12 / 11 on the opposite side. Then, the ultrasonic welding is performed by the ultrasonic vibration of the horn 30 during the clamping and pressing.

[0104] Since both the horn 30 and the anvil 31 include the protrusions 301, 311, more efficient ultrasonic welding can be performed.

[0105] As shown in Figure 5B , Figure 7B , Figure 10A , the protrusions 301 / 311 can be quadrangular hammer shapes. The bottom side of the quadrangular hammer can be a rectangle (including a square) Figure 5B , Figure 7B , a rhombus Figure 10A . The protrusions 301 / 311 can be polygonal hammer shapes other than the quadrangular hammer, respectively. The protrusions 301 / 311 can be conical shapes, as shown in Figure 10B .

[0106] The protrusions 301 / 311 can be regularly arranged in a matrix shape, for example, in the longitudinal and lateral directions, as shown in Figure 5B , Figure 7B , Figure 10C , Figure 10D . The protrusions 301 / 311 can be oriented, for example, in a manner in which the diagonal line of the bottom surface of the protrusions 301 / 311 is inclined with respect to the longitudinal and lateral directions of the arrangement of the protrusions 301 / 311, as shown in Figure 10C , Figure 10D . The plurality of protrusions 301 can have mutually different orientations from each other, and the plurality of protrusions 311 can also have mutually different orientations.

[0107] For example, instead of the pointed protrusions 301 / 311, protrusions 301 / 311 having flat tips can be used.

[0108] In Figures 11A-11CIn this assembly, both the welding head 30 and the anvil 31 include protrusions 301 and 311 with flat front ends. When the welding head 30 and the anvil 31 clamp the main body 11, the main body 12, and the corner support 13 and apply pressure, the protrusions 301 and 311 embed into the stacked portion including the main body 11, the main body 12, and the corner support 13. Furthermore, ultrasonic welding is performed by ultrasonic vibration of the welding head 30.

[0109] Therefore, since the distance between the welding head 30 and the anvil 31 is also shortened, vibration energy can be transmitted efficiently, thus enabling efficient ultrasonic welding of part 131 and part 132.

[0110] Figure 12A This is a front view of bag 10. After the shape of bag 10 is completed by cross-cutting, a process of filling it with contents is sometimes carried out. The weight of the contents inside bag 10 causes a force F ( Figure 12D The purpose is to pull parts 131 and 132 of the corner brace 13 (the bottom corner brace) apart from each other in the ultrasonic welding area 15. Figure 12B As shown, in the force F, the outward component F1 of the bag 10 is greater than the longitudinal component F2 of the bag 10.

[0111] The ultrasonic welding between parts 131 and 132 resists the force F that pulls these parts 131 and 132 apart. In a cross-section perpendicular to the direction of component F1, the intensity of the ultrasonic welding increases accordingly with the ratio of the welded parts. Therefore, in such a case... Figure 12B In the case of such a semi-circular ultrasonic welding area 15, the ultrasonic welding strength at the position of line M is higher than that at the position of line L.

[0112] From the viewpoint of preventing the weight of the contents inside the bag 10 from acting on the outside of the bag 10 and causing parts 131 and 132 to pull apart, it is preferable to... Figure 13A As shown, the ultrasonic welding area 15 has a larger inner length dimension L1 than the outer length dimension L2 of the bag (L1 > L2). For example... Figure 13A As shown, the ultrasonic welding area 15 of the bag 10 may have a trapezoidal shape that narrows outward toward the bag.

[0113] For example, in setting Figure 12B The ultrasonic welding area 15 and Figure 13A When the area of ​​the ultrasonic welding area 15 is the same, Figure 13A The ultrasonic welding area 15 and Figure 12B In comparison, it is stronger than the pull caused by the weight of the contents themselves.

[0114] In the bag-making process, ultrasonic welding device 3 ( Figure 1A )WillFigure 13B The ultrasonic welding region 15 of the sheet 1 is formed in a manner that determines the shapes of the two facing surfaces 300, 310 of the horn 30 and the anvil 31. The sheet 1 is cross-cut at a cross-cut position 560 by a cross-cutting device 56 Figure 1A ), and the ultrasonic welding region 15 is divided into two parts. Thus, as Figure 13A , a bag 10 including a trapezoidal-shaped ultrasonic welding region 15 is manufactured.

[0115] Further, as Figure 13A , if the ultrasonic welding region 15 has an acute angle, there is a problem that the welding can peel off from the acute angle, and thus, as shown in Figure 14A , Figure 14B , the corners of the ultrasonic welding region 15 can have an R shape. The ultrasonic welding region 15 is not limited to a trapezoid shape as in Figure 14A , but can be a quadrangle having corners with an R shape as in Figure 14B . Figure 14A , Figure 14B The ultrasonic welding region 15 can also be formed by the method described in Figure 13B .

[0116] As described above, the efficiency of ultrasonic welding is improved by the protrusions 301 / 311.

[0117] The welding method can also be applied to the main body portion 11, the main body portion 12, and the gusset portion 13 integrally formed by folding a single sheet, instead of the sheet 1. Further, the welding method can also be applied to the main body portion 11, the main body portion 12, and the gusset portion 13 as separate components.

[0118] The gusset portion 13 can also function as a top gusset portion instead of a bottom gusset portion. The welding method can be applied to a side gusset portion that is folded into the main body portion 11, the main body portion 12, as in Patent Document 1.

[0119] As a raw material for the main body portion 11, the main body portion 12, and the gusset portion 13, in addition to a laminate film including a base material layer 16 and a sealant layer 17 as in the embodiments, a raw material having thermoplasticity can be widely used. For example, a single-material raw material excellent in recyclability can be used. Further, a raw material that can reduce the amount of waste resin, such as a raw material including paper as a base material and a resin coated on the paper, can be used. Further, a biodegradable raw material can be used.

Claims

1. A bag making method characterized by: folding a web to form a continuous first body portion, a continuous second body portion, and a continuous gusset portion folded between the first body portion and the second body portion from the web; clamping and pressing the first body portion, the second body portion, and the gusset portion folded between the first body portion and the second body portion with a horn and an anvil, the horn including a facing surface facing the anvil, the anvil including a facing surface facing the horn, at least either one of the horn and the anvil including a plurality of protrusions protruding from the facing surface thereof; welding a first portion and a second portion of the gusset portion to each other by ultrasonic vibration of the horn during the clamping and pressing of the first body portion, the second body portion, and the gusset portion folded between the first body portion and the second body portion with the horn and the anvil; and manufacturing a bag by cross-cutting the web along a width direction of the web across an ultrasonic weld region in which the first portion and the second portion are ultrasonically welded to each other with the horn and the anvil, heat-sealing the web by a sealing unit including a pair of heat-seal bars and softening the first body portion, the second body portion, and the gusset portion before the ultrasonic welding of the first portion and the second portion to each other with the horn and the anvil, the ultrasonic welding being performed in a softened state of the first body portion, the second body portion, and the gusset portion, sequentially to the ultrasonic welding, heat-sealing the ultrasonic weld region by a sealing unit including a pair of heat-seal bars to smooth a sealing surface of the ultrasonic weld region.

2. The bag making method according to claim 1, characterized by: manufacturing the bag including the ultrasonic weld region having a length dimension in an inside direction of the bag larger than a length dimension in an outside direction of the bag.

3. The bag making method according to claim 2, characterized by: manufacturing the bag including the ultrasonic weld region in a trapezoidal shape tapered toward the outside direction of the bag.

4. The bag making method according to claim 1, characterized by: manufacturing the bag having traces of the plurality of protrusions generated at the time of the ultrasonic welding with the horn and the anvil.

5. The bag making method according to claim 1, wherein the plurality of protrusions are pointed, the bag making method includes: piercing the plurality of protrusions into the first body portion or the second body portion and the gusset portion in a manner penetrating the first body portion or the second body portion at the time of clamping and pressing the first body portion, the second body portion, and the gusset portion with the horn and the anvil.

6. The bag making method according to claim 5, wherein the bag making method includes: The plurality of protrusions are pierced into the first body portion, the second body portion, the first portion, and the second portion in a manner that penetrates through the first body portion, the first portion, and the second portion when the first body portion, the second body portion, and the gusset portion are clamped and pressed by the welding horn and the anvil.

7. The bag making method according to claim 1, wherein the plurality of protrusions include flat front ends, the bag making method includes: the plurality of protrusions are embedded in a laminated portion including the first body portion, the second body portion, the first portion, and the second portion when the first body portion, the second body portion, and the gusset portion are clamped and pressed by the welding horn and the anvil.

8. The bag making method according to claim 5, wherein the first body portion, the second body portion, and the gusset portion are each a laminate film including a base material layer containing a base material and a sealant layer containing a sealant having a lower melting point than the base material, the bag making method includes: the sealant is melted by ultrasonic vibration of the welding horn, and the first body portion, the second body portion, the first portion, and the second portion are integrally fused using the sealant.

9. The bag making method according to claim 5, wherein the plurality of protrusions are provided to both the facing surface of the welding horn and the facing surface of the anvil, the protrusions of the welding horn and the protrusions of the anvil are arranged offset from each other in a direction that is at right angles to the facing direction of the welding horn and the anvil in a manner that the front ends of the protrusions of the welding horn and the protrusions of the anvil do not face each other.

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