Apparatus and method for manufacturing elastic composite structures for absorbent sanitary products

Abstract

An apparatus for manufacturing an elastic composite structure for absorbent sanitary products includes an anvil having a welding pattern with at least one anchoring region and at least one passivation region. The anchoring region includes a securement weld that fuses opposing web layers together and forms a secure joint that secures the elastic yarn(s) in place relative to the opposing web layers. The passivation region includes a break bar configured to sever the elastic yarn(s). A method for manufacturing an elastic composite structure includes the steps of: disposing tensioned elastic yarns between web layers; fusing the web layers to form a securement zone that includes a secure joint that fuses the web layers together and secures the tensioned elastic yarn(s) therebetween; and severing the yarns to form a passivation zone between adjacent portions of the securement zone that are free of the tensioned yarns. The method further includes fusing the web layers within the passivation zone. [Selected figure] Figure 2

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This invention claims the benefit of U.S. Provisional Patent Application No. 62 / 623,381, filed January 29, 2018, and U.S. Provisional Patent Application No. 62 / 666,508, filed May 3, 2018, the disclosures of which are incorporated herein by reference in their entireties.

[0002] Embodiments of the present invention relate generally to absorbent sanitary products, and more particularly to improved apparatus and methods for manufacturing elastic composite structures for use in absorbent sanitary products that include elasticized and relatively inelastic regions while minimizing or eliminating the use of consumable adhesives such as glue. [Background technology]

[0003] Absorbent hygienic products, such as disposable diapers, typically include elastic composite structures containing one or more elastic yarns. These elastic composite structures are positioned in various locations throughout the product, including in the waistband and leg cuff regions, as well as all or part of the product's front or back panels. During a typical manufacturing process for elastic composite structures, the elastic yarns are held in tension, and an adhesive is used to secure the elastic yarns between two opposing layers of a nonwoven material or web. The tension on the elastic yarns is then released, causing the web material to wrinkle or fold in the areas containing the bonded elastic yarns. In some applications, it is desirable to provide relatively inelastic regions in the elastic composite structure. To create these distinct regions, adhesive is applied to some areas of the web material and omitted in other areas. The elastic yarns are cut in the adhesive-free areas by a cutting unit, such as a rotary knife unit, and the cut ends of the elastic yarns snap back into the adjacent bonded areas.

[0004] The use of adhesives to bond elastic yarns within elastic composite structures presents numerous disadvantages in both the final product and manufacturing process, including costs associated with consumable materials and undesirable tactile properties (e.g., stiffness) in the final product. While thermal or ultrasonic welding techniques have been proposed as alternatives for bonding and / or severing elastic yarns within elastic composite structures, known ultrasonic techniques for severing elastic yarns tend to create cuts or slits in the web material, thereby reducing web tension in the severed portions of the web and creating undesirable holes in the final product. Another problem with cutting elastic yarns is that the cut ends of the elastic tend to recede beyond the desired boundaries of the elasticized region and land somewhere within the elasticized region, resulting in an incomplete elastic pattern and diminishing the aesthetic and functional properties of the final product.

[0005] Therefore, there is a need for improved apparatus and methods for producing elastic composite structures for absorbent sanitary products that maintain tension in the elastic strands in the elasticized regions of the product and do not cut the web material in the relatively inelastic regions. It would further be desirable for such apparatus and methods to eliminate or minimize the use of consumable adhesives to secure the elastic yarns to opposing web layers. Summary of the Invention [Means for solving the problem]

[0006] According to one aspect of the present invention, a joining apparatus for manufacturing an elastic composite structure having at least one elastic yarn secured between a pair of opposing web layers is disclosed. The joining apparatus includes a rotary anvil having a surface with a weld pattern including at least one anchoring area and at least one passivation area. The at least one anchoring area includes a plurality of securement welds configured to fuse the pair of opposing web layers together and form a secure joint that secures the at least one elastic yarn in place relative to the pair of opposing web layers. The at least one passivation area includes a break bar configured to sever the at least one elastic yarn.

[0007] According to another aspect of the invention, a method of manufacturing an elastic composite structure includes disposing tensioned elastic yarns between a first web layer and a second web layer, and fusing the first web layer to the second web layer to form an anchoring zone having a plurality of discrete anchoring joints fusing the first web layer to the second web layer and securing the tensioned elastic yarns therebetween. The method also includes cutting the tensioned elastic yarns to form an inactive zone of the elastic composite structure free of the tensioned elastic yarns, the inactive zone being located between adjacent portions of the anchoring zone. The method further includes fusing the first web layer to the second web layer within the inactive zone.

[0008] According to another aspect of the present invention, an elastic composite structure includes a tensioning elastic yarn, a first web layer disposed on a first side of the tensioning elastic yarn, a second web layer disposed on a second side of the tensioning elastic yarn, and a pattern of bonds fusing the first web layer to the second web layer. The bond pattern includes an inactive zone including at least one bond pattern, a cut end of a first portion of the tensioning elastic yarn, and a cut end of a second portion of the tensioning elastic yarn. The inactive zone is free of tensioning elastic yarn. The bond pattern also includes anchoring zones separating opposite ends of the inactive zone. The anchoring zone includes a first plurality of bonds in the bond pattern that secure the first portion of the tensioning elastic yarn to the first and second web layers and a second plurality of bonds in the bond pattern that secure the second portion of the tensioning elastic yarn to the second portions of the first and second web layers.

[0009] These and other advantages and features will be more readily understood from the following detailed description of preferred embodiments of the invention, which is provided in connection with the accompanying drawings. [Brief explanation of the drawings]

[0010] The drawings illustrate embodiments presently contemplated for carrying out the invention.

[0011] In the figure,

[0012] [Figure 1]1 is a schematic perspective view of a portion of a manufacturing line for producing elastic composite structures.

[0013] [Figure 2] FIG. 2 is a schematic perspective view of a rotary anvil usable in the manufacturing line of FIG. 1, in accordance with one embodiment of the present invention.

[0014] [Figure 3] 3 is a schematic cross-sectional view of a bonding apparatus including the rotary anvil of FIG. 2 and usable in the manufacturing line of FIG. 1 according to one embodiment of the present invention.

[0015] [Figure 4] FIG. 4 is a detailed view of a portion of the joining apparatus of FIG. 3 showing the horn aligned with a stationary weld on a rotating anvil, according to one embodiment of the present invention.

[0016] [Figure 5] FIG. 4 is a detailed view of a portion of the joining apparatus of FIG. 3 showing a horn aligned with a break bar on a rotating anvil, according to one embodiment of the present invention.

[0017] [Figure 6] FIG. 3 is a top view of a portion of a continuous elastic composite structure produced using the rotary anvil of FIG. 2 in accordance with one embodiment of the present invention.

[0018] [Figure 7] 1 is a schematic top view illustrating the spaced apart relationship between an unsuspended elastic yarn, a pair of fixed joints, a pair of sandwich joints, and a laminated joint according to various embodiments of the present invention.

[0019] [Figure 8] FIG. 2 is a schematic perspective view of a rotary anvil usable in the manufacturing line of FIG. 1 in accordance with another embodiment of the present invention.

[0020] [Figure 9]2 is a top view of a plurality of non-segmented absorbent sanitary products comprising a continuous elastic composite structure produced using the manufacturing line of FIG. 1 according to one embodiment of the present invention.

[0021] [Figure 10] 10 is a flattened representation of an exemplary anvil pattern that can be used to manufacture the continuous elastic composite structure of FIG. 9, in accordance with one embodiment of the present invention.

[0022] [Figure 10A] FIG. 11 is a detailed view of a portion of the rotary anvil of FIG. 10.

[0023] [Figure 11] FIG. 11 is a top view of a portion of a continuous elastic composite structure fabricated using the rotary anvil of FIG. 10 in accordance with an embodiment of the present invention.

[0024] [Figure 11A] FIG. 11B is a detailed view of a portion of the elastic composite structure of FIG. 11A.

[0025] [Figure 12] 10 is a flattened representation of an exemplary anvil pattern that can be used to manufacture one of the elastic composite structures of FIG. 9, according to another embodiment of the present invention.

[0026] [Figure 13] FIG. 13 is a top view of a portion of a continuous elastic composite structure produced using the rotary anvil of FIG. 12 according to another embodiment of the present invention.

[0027] [Figure 13A] FIG. 14 is a detailed view of a portion of the elastic composite structure of FIG. 13.

[0028] [Figure 14] 10 is a flattened representation of an exemplary anvil pattern that can be used to manufacture the continuous elastic composite structure of FIG. 9 in accordance with another embodiment of the present invention.

[0029] [Figure 15] FIG. 15 is a top view of a portion of a continuous elastic composite structure produced using the rotary anvil of FIG. 14 according to another embodiment of the present invention.

[0030] [Figure 16] 10 is a flattened representation of an exemplary anvil pattern that can be used to manufacture the continuous elastic composite structure of FIG. 9 in accordance with yet another embodiment of the present invention.

[0031] [Figure 17] FIG. 17 is a top view of a portion of a continuous elastic composite structure produced using the rotary anvil of FIG. 16 according to another embodiment of the present invention.

[0032] [Figure 18] 10A-10C illustrate a technique for manufacturing an elastic composite structure according to another embodiment of the present invention.

[0033] [Figure 19] 19 is a flattened representation of an exemplary anvil pattern that can be used to manufacture an elastic composite structure according to the technique of FIG. 18, in accordance with one embodiment of the present invention.

[0034] [Figure 20] 19 is a flattened representation of an exemplary anvil pattern that can be used to manufacture an elastic composite structure according to the technique of FIG. 18, in accordance with one embodiment of the present invention.

[0035] [Figure 21] FIG. 21 is a top view of a portion of an elastic composite structure produced using the rotary anvil of FIGS. 19 and 20 according to another embodiment of the present invention.

[0036] [Figure 22] 10A-10C illustrate a technique for manufacturing an elastic composite structure according to yet another embodiment of the present invention.

[0037] [Figure 23] 10A-10C illustrate a technique for manufacturing an elastic composite structure according to yet another embodiment of the present invention.

[0038] [Figure 24] 24 is a cross-sectional view of a portion of a cutting unit that can be used to manufacture an elastic composite structure according to the technique of FIG. 23, in accordance with one embodiment of the present invention.

[0039] [Figure 25] 10A-10C illustrate a technique for manufacturing an elastic composite structure according to yet another embodiment of the present invention.

[0040] [Figure 26] 26 is a flattened representation of an exemplary anvil pattern on a first rotating anvil that may be used to manufacture an elastic composite structure according to the technique of FIG. 25 , in accordance with one embodiment of the present invention.

[0041] [Figure 27] 26 is a flattened representation of the periphery of a cutting unit that can be used to manufacture elastic composite structures according to the technique of FIG. 25, in accordance with one embodiment of the present invention.

[0042] [Figure 28] 26 is a flattened representation of an exemplary anvil pattern on a second rotating anvil that may be used to manufacture an elastic composite structure according to the technique of FIG. 25 , in accordance with one embodiment of the present invention.

[0043] [Figure 29] 28 is a top view of a portion of a continuous elastic composite structure manufactured using the rotary anvil of FIGS. 26 and 28 and the cutting unit of FIG. 27 according to another embodiment of the present invention.

[0044] [Figure 30] 2 is a schematic cross-sectional view of a bonding device usable in the manufacturing line of FIG. 1 in accordance with an embodiment of the present invention.

[0045] [Figure 31] 31 is a top view of a continuous elastic composite structure manufactured using the bonding apparatus of FIG. 30 according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0046]

[0006] Embodiments of the present invention provide methods and apparatus for producing elastic composite structures that include one or more activated or elasticized zones in which one or more tensioned elastic yarns are fixed or secured in place relative to opposing web layers, and one or more inactive zones that are inelastic relative to the elasticized zones. The resulting elastic composite structures can be used in absorbent hygiene products, such as diapers, disposable adult pants, or feminine care products. As one non-limiting example, the elastic composite structures described herein can be waistbands for diapers that include inactive zones in the areas where the absorbent core is bonded to the waistband.

[0047] Referring now to FIG. 1 , a portion of an exemplary manufacturing line 10 according to one embodiment of the present invention is shown. As shown, a first web layer 12 is fed in a machine direction 14. A second web layer 16 is likewise fed in the machine direction 14. The first web layer 12 and the second web layer 16 are materials capable of fusing together upon application of applied energy that softens or melts one or both of the webs 12, 16 and bonds them together without the use of an intermediate layer of adhesive, such as glue. The pair of opposing web layers 12, 16 may be the same type of material or different materials, according to alternative embodiments. As non-limiting examples, the first and second web layers 12, 16 may comprise nonwoven materials, woven materials, films, foams, and / or composites or laminates of these material types.

[0048] One or more elastic yarns 18 are disposed between the first and second web layers 12, 16. While the following description refers to plural elastic yarns, it should be understood that the methods described herein can be used to manufacture elastic composite structures including a single elastic yarn or any number of multiple elastic yarns. The elastic yarns 18 travel in the machine direction 14 under tension from a creel assembly (not shown) or similar device. The elastic yarns 18 can be composed of any suitable elastic material, including, by way of non-limiting example, sheets, strands, or ribbons of, for example, thermoplastic elastomer, natural or synthetic rubber, or LYCRA. Each elastic yarn 18 can be provided in the form of an individual elastomeric strand, or can be a manufactured multifilament product including many individual elastomeric filaments bonded together, such as by a dry-spinning manufacturing process, to form a single, coalesced elastic yarn 18.

[0049] The elastic yarns 18 may have any suitable cross-sectional shape that facilitates the formation of an elastic composite structure having the desired elasticity, visual aesthetics, and manufacturability. By way of non-limiting example, the elastic yarns 18 may have a round, rectangular, square, or irregular cross-sectional shape, such as when each elastic yarn 18 is a multifilament product.

[0050] 1 and described herein as physically separate components, it is contemplated that alternative embodiments may utilize a folded unitary web structure to capture the elastic yarns 18 between upper and lower layers of the unitary web structure. In such embodiments, the portion of the unitary structure located below the elastic yarns 18 is referred to as the first web layer 12, and the portion of the unitary structure located above the elastic yarns 18 is referred to as the second web layer 16.

[0051] The manufacturing line 10 includes one or more feed assemblies 20, such as guide rollers, employed to precisely position and (optionally) tension the elastic yarn 18 as it moves in the machine direction 14 toward the bonding device 22. Immediately above the bonding device 22 are one or more assemblies that feed and guide the first and second web layers 12, 16 and the elastic yarn 18 into the bonding device 22. In the illustrated embodiment, these feed assemblies include an upper roller 24, a lower roller 26, and a strand guide roller 28 that guides a composite assembly 30 including the first web layer 12, the second web layer 16, and the elastic yarn 18 into the bonding device 22. It is contemplated that in alternative embodiments, the rollers 24, 26, 28 may be replaced with other known types of feed assemblies and / or may be replaced with a single roller unit or other known types of feed assemblies.

[0052] The bonding apparatus 22, in alternative embodiments, may be any known ultrasonic welding system, including, by way of non-limiting example, a rotary ultrasonic welding system or a blade ultrasonic welding system. In the illustrated embodiment, the bonding apparatus 22 includes a rotating anvil 32 and an ultrasonic fixed-blade horn 34, also known as a sonotrode, which cooperate with each other to bond (i.e., fuse) the first web layer 12 to the second web layer 16. Alternative embodiments may include multiple fixed-blade horns, or one or more rotary horns. During the bonding process, the elastic yarn 18 is secured or fixed in place relative to the first and second web layers 12, 16, as described in detail below.

[0053] The bonding apparatus 22 also includes one or more frames 36 that support and / or house a motor (not shown) that drives the ultrasonic horn 34, a vibration control unit (not shown) that ultrasonically excites the horn 34 to vibrate it, and a second motor (not shown) that drives the anvil 32. The horn 34 and anvil 32 are positioned in a spaced-apart relationship relative to one another to facilitate ultrasonically bonding the first and second web layers 12, 16 to one another while the elastic yarn 18 is held within the space between the horn 34 and the anvil 32. During the bonding process, the first and second web layers 12, 16 are exposed to ultrasonic radiation from the horn 34, which increases the vibration of particles within the first and second web layers 12, 16. The ultrasonic radiation or energy is focused at specific bond points where frictional heat fuses the first and second web layers 12, 16 to one another without the need for a consumable adhesive. Although the bonding apparatus 22 is described herein as an ultrasonic bonding assembly that ultrasonically fuses the first web layer 12 to the second web layer 16, it is contemplated that the techniques described herein may extend to any other known welding or bonding technique that fuses two or more layers of material without the use of adhesives, including sonic, heat, or pressure bonding techniques, and various other forms of welding known in the industry.

[0054] Referring now to FIG. 2 , an anvil according to one embodiment of the present invention is shown. As shown, the anvil 32 includes an arrangement of discrete projections or welds 38 extending outward from the anvil face 40. These welds 38 are constructed to (A) fuse the first and second web layers 12, 16 together and (B) hold or secure the elastic yarn 18 in place relative to the first and second web layers 12, 16 in the resulting elastic composite structure. As explained in more detail below, the securement welds 38 are designed so that an elastic yarn 18 passing between two adjacent securement welds 38 on the face 40 of the anvil 32 is secured in place relative to the first and second web layers 12, 16 by frictional resistance that prevents the elastic yarn 18 from sliding across the resulting pair of joints. The locations of the securement welds 38 define a securement area 42 of the anvil 32.

[0055] The anvil 32 also includes one or more additional protrusions, referred to herein as layup welds 44. Like the restraint or securement welds 38, the layup welds 44 fuse the first and second web layers 12, 16 together. The layup welds 44 differ from the securement welds 38 because they do not secure the elastic yarn 18 in place relative to the first and second web layers 12, 16.

[0056] The anvil 32 also includes one or more edges or break bars 46 extending outward from the anvil face 40. Each break bar 46 is configured to break the tensioned elastic yarn 18 as it passes between the horn 34 and the anvil 32 without cutting or perforating the first or second web layer 12, 16. The pressure or clamping force exerted on a given elastic yarn 18 as it passes between the horn 34 and the break bar 46 imparts stress to the elastic yarn 18 to break the elastic yarn 18. In a preferred embodiment, the break bar(s) 46 are constructed so as not to bond the first and second web layers 12, 16 to one another. In an alternative embodiment, the break bar(s) 46 form a bond between the first and second web layers 12, 16 having a geometry that mirrors the geometry of the working surface of the respective break bar 46. The fixation weld 38 , the build-up weld(s) 44 , and the break bar(s) 46 together define a pattern of projections 48 or weld pattern that extend outward from the face 40 of the anvil 32 .

[0057] In the illustrated embodiment, the break bar 46 has a length equal to or substantially equal to the overall length 50 of the pattern of projections 48. In alternative embodiments, each break bar 46 may be sized to span only a portion of the overall anvil length 50, as described in further detail below. Optionally, the break bar(s) 46 may include one or more grooves 56 (shown in phantom) recessed into the working surface 58 of the break bar(s) 46. In yet another embodiment, the break bar 46 is constructed of a series of distinct but closely spaced projections or pinch welds, so called because the close spacing between two adjacent pinch welds acts as a pinch point to sever the elastic thread 18 passing through the adjacent pinch welds during the joining process. The break bar(s) 46 may be straight and oriented parallel to the axis of rotation 60 of the anvil 32 as shown, oriented at an angle relative to the axis of rotation 60, or have any alternative geometric configuration determined based on design specifications to achieve the desired results of severing the elastic yarn 18.

[0058] The location of the break bars 46 defines a passivation area 62 of the anvil 32, which corresponds to the area of ​​passivated or broken elastic yarns in the produced elastic composite structure, hereafter referred to as the passivation zone. One or more layup welds 44 are also located within the passivation area 62 of the anvil 32. In the illustrated embodiment, the passivation area 62 includes one break bar 46, with layup welds 44 located on both sides of the break bar 46. Alternative embodiments may include multiple break bars 46 within a given passivation area 62, with layup welds 44 located on one or both sides of each break bar 46. In yet another embodiment, layup welds 44 may be omitted entirely from the passivation area 62.

[0059] The particular sizes, shapes, and general arrangements of the fixation welds 38, the layer welds 44, and the break bar 46, as well as the total number of welds 38, 44, and break bar(s) 46 shown in FIG. 2 are intended to represent representative, non-limiting examples of the overall pattern 48 of protrusions on the anvil 32. Alternate embodiments may include any number of welds 38, 44 and break bar(s) 46 arranged in any number of alternative configurations to achieve a desired joint pattern on the final product. The working surfaces of each of the fixation welds 38 and the layer welds 44 may be configured to form joints of similar size and shape, or joints of different sizes and / or shapes in alternate embodiments. By way of non-limiting example, the land surfaces of each of the fixation welds 38 and the layer welds 44 may be circular, rectangular, crescent-shaped, or may have an irregular shape that can be selected to form a desired overall pattern on the final product. As explained above, the resulting bond pattern will include one or more anchoring zones that secure one or more elastic yarns 18 in place under tension relative to the first and second web layers 12, 16, and one or more inactive areas or zones that are free of tensioning elastic yarns 18. Absent tensioning elastic yarns 18, these inactive zones define relatively elastic regions within the resulting elastic composite structure.

[0060] In a preferred embodiment, the fixation weld 38, the buildup weld 44, and the break bar(s) 46 are formed on the anvil 32 using a machining process that removes bulk material from the anvil 32 to create the desired raised pattern 48 of protrusions against the face 40 of the anvil 32. Alternatively, the fixation weld 38, the buildup weld 44, and / or the break bar(s) 46 may be provided on one or more inserts that are mechanically coupled to the face 40 of the anvil 32.

[0061] 3, the working surface 64 of the horn 34, in one non-limiting embodiment, has a smooth or substantially smooth surface contour. Alternatively, the working surface 64 may include an arrangement of protrusions that match or align with the pattern of protrusions 48 on the anvil 32 to further facilitate fusing the first web layer 12 to the second web layer 16 and securing the elastic yarn 18 in place relative to the first and second web layers 12, 16.

[0062] During the manufacturing process, the first and second web layers 12, 16 are positioned between the face 40 of the anvil 32 and the working surface 64 of the horn 34, as shown in FIG. 3. The elastic yarn 18 is positioned in tension between the first and second web layers 12, 16. As shown generally in FIG. 3 and in more detail in FIG. 4, the working surface 64 of the horn 34 is controlled to maintain a nip gap 66 between the working surface 64 of the horn 34 and the land surfaces 68, 70 of the fixation weld 38 and the layup weld 44, respectively. The size of the nip gap 66 is determined based on manufacturing process parameters to facilitate bonding between the first and second web layers 12, 16. The bonding apparatus 22 may include any known positioning means 67 that applies a force to at least one of the horn 34 and the anvil 32 to maintain the desired nip gap 66 between the horn 34 and the anvil 32. Positioning means 67 may be, by way of non-limiting example, a pneumatic assembly (not shown) or a mechanical camshaft (not shown).

[0063] In alternative embodiments, the fixed weld 38 may have a flat working surface, flat sides, or some mixture of curved and straight working surfaces and sides. In the embodiment shown in FIG. 4 , the land surface 68 of the fixed weld 38 has an arcuate or curved surface profile. This curved profile allows the first and second weld layers 12, 16 to slide against the face 40 of the anvil 32 during the joining process, thereby increasing or decreasing the speed at which the composite assembly 30, including the tensioned elastic strand 18 and the first and second web layers 12, 16, advances toward the joining device 22 relative to the rotational speed of the anvil 32. When the composite web / yarn assembly 30 advances at a speed greater than the speed of the anvil 32, the resulting joints are spaced apart by a distance greater than the radial spacing between adjacent welds 38, 44 on the anvil face 40. Similarly, slowing the feed rate of the composite web / yarn assembly 30 relative to the speed of the anvil 32 results in bonds spaced a distance less than the radial spacing between adjacent welds 38, 44 on the anvil face 40. The speed mismatch or difference between the web speed and the anvil speed can be controlled to accommodate size variations in the final product. As a result, bonding of elastic composites for one size diaper can be performed with little or no slippage, while bonding of elastic composites for larger or smaller diapers can be performed with a greater amount of slippage. Because the same anvil 32 can be used to produce multiple sizes of elastic composite structures for use in different size products, the manufacturing line 10 equipped with the anvil 32 thus provides dynamic sizing without the need to change the tooling settings of the manufacturing line 10.

[0064] 5 is a detailed view of the relationship between the horn 34 and the break bar 46 on the anvil 32. In the illustrated embodiment, the break bar 46 has straight sides 72 and a curved working surface 58 to enable slippage between the anvil 32 and the first and second web layers 12, 16 in a manner similar to that described above with respect to the securement weld 38. Alternatively, the entire working surface 58 of the break bar 46 may have a continuous arcuate profile similar to the securement weld 38 of FIG. 4. In yet other embodiments, the working surface 58 may be flat or planar, the sides 72 may be curved, or the break bar 46 may be configured with any other geometric profile that achieves its intended function of severing the elastic yarn 18 and, optionally, fusing the first and second web layers 12, 16.

[0065] 5, the working surface 64 of the horn 34 is spaced from the working surface 58 of the break bar(s) 46 by a nip gap 76. In one embodiment, the nip gap 76 is equal to or substantially equal to the nip gap 66 between the working surface 64 of the horn 34 and the land surfaces 68, 70 of the fixation or lay-up welds 38, 44. In alternative embodiments, it may be desirable for the break bar(s) 46 to form a bond between the first and second web layers 12, 16 by virtue of the geometry of the break bar(s) 46, the size of the nip gap 76, or a combination thereof.

[0066] 6 shows a portion of an elastic composite structure 78 formed using an anvil 32 having the pattern of projections 48 shown in FIG. 2. The elastic composite structure 78 is shown in a drawn state in which the elastic yarns 18 have been stretched to the point where the first and second web layers 12, 16 are flat or substantially flat. The elastic yarns 18 are located between the first and second web layers 12, 16 and are oriented along a longitudinal axis 80 of the elastic composite structure 78. While the illustrated embodiment includes three (3) elastic yarns 18, it is contemplated that alternative embodiments may include a single elastic yarn 18 or any number of multiple elastic yarns 18, based on the design specifications of the final product.

[0067] The first and second web layers 12, 16 are fused together by securement joints 82 where securement welds 38 (FIG. 2) on the anvil 32 communicate with the web layers 12, 16, and by lamination joints 84 where lamination welds 44 (FIG. 2) on the anvil 32 communicate with the web layers 12, 16. The break bar(s) 46 on the anvil 32 break the elastic yarns 18, flicking them back toward the nearest securement joint 82. When the elastic composite structure 78 is allowed to relax, the elastic yarns 18 attempt to expand or expand to return to an untensioned or relaxed state. As the elastic yarns 18 expand, frictional forces constrain or secure the yarns 18 between adjacent securement joints 82 and the first and second web layers 12, 16. The result is an elastic composite structure 78 that includes one or more elastic or fixed regions or zones 86 corresponding to the fixed regions 86 of the anvil 32 and one or more non-elastic or inactive zones 88 corresponding to the inactive regions 62 of the anvil 32. The length 90 of the fixed zone(s) 86 and the length 92 of the inactive zone(s) 88 are defined by control of the rotational speed and anvil geometry of the anvil 32 relative to the feed rate of the composite web / yarn assembly 30 during the bonding process.

[0068] Referring now to FIG. 7 , in conjunction with FIG. 2 where appropriate, in one embodiment, the proximal edges of adjacent securement welds 38 are spaced apart a distance 94 that is less than the strand diameter 96 of a given elastic yarn 18 in an untensioned state. As used herein, the phrase "strand diameter" refers to the smallest measurable cross-sectional width of the elastic yarn 18 in an untensioned state. In embodiments where the given elastic yarn 18 is of monofilament construction, the strand diameter is the minor diameter or smallest measurable width of the monofilament construction in an untensioned state. In embodiments where the given elastic yarn 18 is of multifilament construction, the phrase "strand diameter" refers to the shortest distance between opposing edges of a profile that defines a generally irregular cross-sectional area. Adjacent fixation welds 38 on the anvil 32 form a pair of adjacent fixation joints 82 that act to secure or fix the elastic yarn 18 because the distance 98 between the proximal edges of adjacent fixation joints 82 is less than the strand diameter 96 of the untensioned elastic yarn 18, as shown in FIG.

[0069] In embodiments in which the break bar 46 is constructed with separate clamp welds, adjacent clamp welds form a pair of adjacent clamp joints 100 having proximal edges spaced apart by a distance 102 that is less than the strand diameter 96 and the distance 98 between adjacent fixed joints 82.

[0070] In embodiments in which the anvil 32 of FIG. 2 includes multiple adjacent stacked welds 44, the adjacent welds 44 are spaced apart a distance 104 to form a pair of adjacent stacked joints 84 having proximal edges spaced apart by either (A) a distance 106 greater than the strand diameter 96 of a single unsuspended elastic yarn 18, as shown by stacked joint 84A of FIG. 7, or (B) a distance 108 greater than the sum of the strand diameters 96 of two or more unsuspended elastic yarns 18, as shown by stacked joint 84B.

[0071] FIG. 8 illustrates an anvil 32 according to an alternative embodiment of the present invention. The anvil 32 includes a pattern of projections 110 that differs from the pattern of projections 48 described with respect to FIG. 2 in that it includes a narrower break bar 46 and does not include a laminate weld 44. In such an embodiment, the resulting elastic composite structure includes an anchoring zone similar to the anchoring zone 86 shown in FIG. 6 and an inactive zone that includes a bond line formed by the break bar 46 but does not include a laminate joint. In one embodiment, an adhesive may be used to bond the first and second web layers 12, 16 to one another within the inactive zone. Alternatively, a laminate joint similar to the laminate joint 84 of FIG. 6 may be formed within the inactive zone using a second anvil unit positioned downstream of the anvil 32, as described in more detail below.

[0072] In the embodiment described with reference to Figures 2 through 8, the anchoring zone 86 and the inactive zone 88 span a similar width of the resulting elastic composite structure 78 in the cross-machine direction 54 as a result of the particular configuration of the break bar(s) 46, the laminate weld(s) 44 (when used), and the anchoring welds 38 on the anvil 32. Figures 10, 12, 14, and 16 illustrate alternative anvil projection patterns that may be used with the joining apparatus 22 of Figure 1 to form inactive zones 88 that span only a portion of the overall width of the resulting elastic composite structure. These alternative projection patterns may be used to produce continuous elastic composite structures, such as the front and back waist panels 112, 114 shown in Figure 9. As illustrated, the front and back waist panels 112, 114 include anchoring zones 86 that include a plurality of anchoring bonds that secure the elastic yarns 18, and inactive zones 88 that define attachment locations for the respective absorbent cores 116 of the disposable diaper or pant, and in some embodiments may include laminate bonds. Line 118 represents the product cut line. It should be understood that each of Figures 10, 12, 14, and 16 illustrates one exemplary, non-limiting pattern of projections for producing waist panels 112, 114. The concepts described herein may be extended to using anvils having alternative patterns of projections different from those described with respect to Figures 10, 12, 14, and 16 to produce a final product having one or more anchoring zones and one or more inactive zones. Accordingly, it is contemplated that the pattern of projections on the anvil may be varied from that shown herein to create an elastic composite structure including one or more anchoring zones and one or more inactive zones that differ in size and / or location relative to the embodiments specifically shown herein.

[0073] 10 is a flattened representation of the outer peripheral surface 40 of the anvil 32 according to an embodiment in which the anvil 32 includes a pattern of projections 120 that form the passivated zone 88 and the securement zone 86 of FIG. 9. The pattern of projections 120 includes a plurality of securement weld lines 122 spaced apart from one another along a circumferential axis 124 of the anvil face 40. The securement weld lines 122 define a securement region 126 of the pattern of projections 120. The pattern of projections 120 also includes a break bar 128 and a plurality of stacked weld lines 130 that collectively define a passivated region 132.

[0074] 10A, each of the fixation welds 122 includes a plurality of separate fixation welds 38. Similarly, each of the layered welds 130 includes a plurality of separate layered welds 44, which are spaced apart a distance greater than the distance between the fixation welds 38. In alternative embodiments, each layered weld 130 may consist of a single layered weld 44, or the layered welds 130 may be omitted altogether. The break bar 128 may be formed with a continuous working surface, as shown, or may include one or more grooves similar to the grooves 56 of FIG. 2.

[0075] In the illustrated embodiment, the break bar 128, layup weld line 130, and fixation weld line 122 have similar sinusoidal geometries that form a generally sinusoidal pattern across the anvil face 40. In this embodiment, the break bar 128 is constructed to fuse the first and second web layers 12, 16 together and sever the elastic yarn(s) 18 passing between the break bar 128 and the horn 34 ( FIG. 1 ) during the joining process. In alternative embodiments, one or more of the layup weld lines 130 directly adjacent the leading and trailing edges of the passivation region 62 may be omitted. The break bar 128, layup weld line 130, and fixation weld line 122 may be straight, curved, or, in alternative embodiments, otherwise positioned to create a continuous and repeating overall pattern in the final product.

[0076] As shown in Figure 11, the bonding process creates an overall pattern of fixation bond lines 134 and layup bond lines 136 on the resulting elastic composite structure 138 that mirrors the geometry of the fixation weld lines 122 and layup weld lines 130 in the projection pattern 120 of Figure 10. Thus, in embodiments where the weld lines 122, 130 are sinusoidal, the resulting bond lines 134, 136 have a similar sinusoidal pattern. Alternative bond patterns on the elastic composite structure 138 can be achieved by varying the geometry of the corresponding weld lines 122, 130 on the anvil 32. In the illustrated embodiment, a continuous bond line 140 is formed by a break bar 128, which severs the elastic yarn 18. The severed or cut end 142 of the elastic yarn 18 snaps back toward the nearest fixed bond line 134, thereby securing the two segmented portions 18A, 18B of a given cut elastic yarn 18 in place against the first and second web layers 12, 16 under tension. In an alternative embodiment, the break bar 128 may be configured to sever the elastic yarn 18 without fusing the first and second web layers 12, 16. The fixed bond line 134 also bonds the first and second web layers 12, 16 to one another and defines the fixation zone 86. The first and second web layers 12, 16 are joined to one another within the inactive zone 88 by a continuous bond line 140 formed by the break bar 128 and by a lamination bond line 136 formed by the lamination weld line 130 on the anvil 32. As with the above embodiment, the fixed bond lines 134 collectively define the fixation zone 86 on the elastic composite structure 138. The inactive zone 88 defines the lamination bond line 136 and the running bond line 140 (if formed).

[0077] Figure 12 shows a pattern of projections 144 on anvil 32 according to an alternative embodiment of the present invention. Pattern of projections 144 includes fixation welds 122 arranged similarly to those included in pattern of projections 120 of Figure 10 and including separate fixation welds similar to fixation welds 38 of Figure 10A. Pattern of projections 144 also includes a pair of break bars 128, one located at the leading edge of passivation region 132 and the other located at the trailing edge of passivation region 132. A series of layered welds 130 are positioned between break bars 128, each including separate layered welds similar to layered welds 44 of Figure 10A.

[0078] The pattern of protrusions 144 creates an elastic composite structure 138 that includes the pattern of bonds shown in Figure 13. Because each break bar 128 severs the elastic yarn 18 as the elastic yarn 18 passes over it, the use of two break bars 128 creates two break points in a given elastic yarn 18 passing through the inactivated region 132 of the anvil 32, resulting in severed elastic yarn portions 146 for each of those elastic yarns 18. These severed elastic portions 146 are maintained within the inactivated zone 88 of the resulting elastic composite structure 138, as shown in Figure 13.

[0079] FIG. 14 illustrates an alternative pattern 148 of protrusions on the anvil 32 according to another embodiment of the present invention. The fastening region 126 includes fixed weld lines 122 similar to those in FIGS. 10 and 11. The passivation region 132 includes an alternating pattern of fixed weld lines 122 and break bars 128. In one embodiment, the break bars 128 are constructed so as not to fuse the first and second web layers 12, 16 together. During the bonding process, each elastic yarn 18 passing through the passivation region 132 of the anvil 32 is severed by each of the break bars 128. The result is an elastic composite structure 138, shown in FIG. 15, including a series of severed elastic yarn portions 146 corresponding to each elastic yarn 18 passing through the passivation region 132. These severed elastic yarn portions 146 are secured in place by fixed bond lines 134 in the fastening zone 86.

[0080] Yet another alternative pattern of protrusions 150 is shown in FIG. 16 . In this embodiment, as shown in FIG. 17 , the passivation areas 132 of the pattern 150 include a continuous weld pattern 152 that simultaneously severs the elastic yarns 18 to form a corresponding unbroken bond pattern 154 or geometric design on the resulting elastic composite structure 138. Each elastic yarn 18 passing between the weld pattern 152 and the horn 34 ( FIG. 1 ) during the bonding process may be severed one or more times based on the geometry of the weld pattern 152. In the illustrated embodiment, the weld pattern 152 severs each of the affected elastic yarns 18 two or more times, resulting in many severed elastic yarn portions 146 contained within the bond pattern 154 of the elastic composite structure 138. The continuous weld pattern 152 shown in FIG. 16 should be understood as just one example of a weld pattern geometry that may be implemented within the pattern of protrusions 150. In alternative embodiments, the pattern of protrusions 150 may include a continuous weld pattern 152 that forms any desired pattern, shape, design, logo, etc. on the resulting elastic composite structure 138 .

[0081] The bond patterns depicted on the elastic composite structure 138 of Figures 11, 13, 15, and 17 have been described above as being formed using a single anvil 32 having a pattern of projections that define the locations and boundaries of the stationary and inert zones on the final product. Alternatively, similar final products may be produced using two or more anvils, each containing a portion of the overall pattern of projections. In such embodiments, the anvils are positioned adjacent to one another in the cross-machine direction 54 (i.e., perpendicular to the machine direction 14) and configured to rotate simultaneously about a common axis of rotation.

[0082] In an alternative embodiment, the first and second web layers 12, 16 are fused together using multiple bonding devices arranged in series in the machine direction 14. Referring to FIG. 1 , a first bonding device 22 includes a first anvil 32 including a pattern of protrusions forming a first portion of the overall bonding pattern, and one or more horns 34. A second bonding device 156 is positioned downstream from the first bonding device 22 in the machine direction 14. The second bonding device 156 includes a second horn 158 and a second anvil 160 including a second pattern of protrusions that completes the overall bonding pattern. In alternative embodiments, the second bonding device 156 may include multiple horns and / or multiple anvils.

[0083] FIG. 18 illustrates an exemplary manufacturing method 162 utilizing this two-stage anvil arrangement. The method 162 begins at step 164 by operating the first anvil 32 in combination with the horn 34 to join the first and second web layers 12, 16 together. The anvil 32 includes one or more break bars 46 that cut or sever the elastic yarns 18. The resulting intermediate product 166 is shown in FIG. 18 with the positions of the horn 34 and break bar(s) 46 superimposed on the intermediate product 166 for reference. The intermediate product 166 includes an anchoring zone 86 and an inactive zone 88, which, at this point in the manufacturing process, do not include a laminate joint 84. The anchoring zone 86 includes a anchoring weld line 122, similar to that described with respect to FIGS. 11, 13, 15, and 17, and a anchoring bond line 134 formed by a corresponding anchoring weld 38, similar to any of those described with respect to FIGS. 2, 10, 12, 14, and 16.

[0084] The method 162 continues at step 168 by fusing the first and second web layers 12, 16 within the resulting inert zone(s) 88 via a pattern of lay-up welds or lay-up weld lines similar to any of those described with respect to Figures 2, 10, 12, 14, and 16. The result is an elastic composite structure 138 including one or more anchoring zones 86 and one or more inert zones 88.

[0085] 19 and 20 show flattened representations of the respective outer peripheral surfaces of the first anvil 32 and the second anvil 160 according to one embodiment of the present invention. The first anvil 32 includes a first pattern of protrusions 170 having a securing weld line 122 and a break bar 128. The second anvil 160 includes a second pattern of protrusions 172 including a series of laminate weld lines 130. When the anvils 32, 160 are operated in the manner described with respect to the method 162 of FIG. 18, the first and second patterns of protrusions 170, 172 form the elastic composite structure 138 shown in FIG. 21. In the illustrated embodiment, the break bar 128 shown in FIG. 19 is not configured to form a bond between the first and second web layers 12, 16 of the elastic composite structure 138 (FIG. 21). In an alternative embodiment, the geometry of the break bar 128 may be designed to form a bond line within the inactive zone 88.

[0086] An alternative two-step bonding method 174 is shown in FIG. 22. Similar to method 162 of FIG. 18, technique 174 utilizes a pair of anvils 32, 160 arranged in series in the machine direction 14 to form the overall bond pattern. Methods 162, 174 differ from one another in that they use different patterns of protrusions on the anvils 32, 160. During a first step 176 of method 174, a first portion of the overall bond pattern is formed using a first anvil 32 that includes a pattern of protrusions that form an intermediate product 178. As shown in FIG. 22, intermediate product 178 includes distinct fastening zones 86 that span the width of product 178. The first anvil 32 also includes one or more break bars 46 that separate the elastic to create one or more inactive zones 88.

[0087] During a second step 180 of the method 174, the overall bond pattern is completed using a first anvil 160 including one or more layup weld lines 130 as well as a fixation weld line 122. A second anvil 160 forms one or more layup joints 84 within the inactive zone 88 and one or more additional fixation zones 86, resulting in a resilient composite structure 138.

[0088] Yet another alternative method 182 for forming an elastic composite structure 138 is shown in FIG. 23. The method 182 utilizes a manufacturing line 10 including a first anvil 32, a cutting unit 184 positioned downstream from the first anvil 32 as shown in FIG. 1, and a second anvil 160 positioned downstream from the cutting unit 184. A detailed view of a portion of the cutting unit 184, according to one embodiment of the present invention, is provided in FIG. 24. The cutting unit 184 includes a rotary knife roll 186 aligned with a rotary anvil 188. Knives 190 are positioned within inserts 192 on the rotary knife roll 186. Anvil insert 194 is inserted into the rotary anvil 188. The cutting unit 184 may include a single knife 190 and corresponding anvil insert 194, or multiple knife 190 / anvil insert 194 pairs spaced apart around the respective faces of the knife unit 186 and rotary anvil 188. Each rotary knife roll 186 and corresponding rotary anvil 188 is spaced a distance apart that defines a nip gap 196 between the knives 190 and an operative surface 198 of the anvil insert 194. In a preferred embodiment, the nip gap 196 is defined so that the force of the knives 190 against the anvil insert 194 is sufficient to sever the elastic yarn 18 without severing or creating slits in the first and second web layers 12, 16.

[0089] In the illustrated embodiment, the working surface 198 of the anvil insert 194 is sloped between its leading edge 200 and trailing edge 202. The sloped configuration of the working surface 198 allows the size of the nip gap 196 to be adjusted by adjusting the phase or relative rotational position between the knife 190 and the anvil insert 194. In alternative embodiments, the working surface 198 may be flat, curved, or any other geometric shape to facilitate the desired cutting function. The anvil insert 194 may be omitted entirely in another embodiment. The cutting unit 184 is described herein as a crush-cut unit. In another embodiment, the cutting unit 184 may be replaced with alternative types of cutting units known in the art, including units with rotating or non-rotating configurations and laser systems.

[0090] 23 , in combination with FIGS. 1-3 as appropriate, method 182 begins with step 204, in which a first anvil 32 is used to form a discrete fixed bond zone 86 on an intermediate product 206. In one embodiment, the anvil 32 includes a uniform pattern of fixed welds 38 extending around the outer circumferential surface 40 of the anvil 32. The horn 34 oscillates up and down in the direction of arrows 208, 210 ( FIG. 3 ) between raised and lowered positions during the joining process. This oscillation may be accomplished using a mechanical camshaft assembly coupled to the horn 34 or other known position control mechanism 67. When the horn 34 is in its lowered position, a fixed bond 82 is formed within the desired fixed bond zone 86. When the horn 34 is in its raised position, the horn 34 is out of communication with the anvil 32, and a bond-free region 212 is formed within the intermediate product 206. In step 214, the partially bonded intermediate product 206 passes through a cutting unit 184, thereby severing one or more of the elastic yarns 18 and forming one or more inactive zones 88 to result in an intermediate product 216. The intermediate product 216 passes through a second anvil 160 in step 218, which includes a pattern of protrusions including fixation weld lines and lay-up weld lines that complete the bond pattern on the elastic composite structure 138.

[0091] FIG. 25 illustrates an alternative method 220 for forming an elastic composite structure 138 using the optional cutting unit 184 and dual bonding apparatus 22, 156 arrangement of FIG. 1. In this method 220, the bonding apparatus 22 includes at least two horns 34A, 34B and an anvil 32 having a uniform pattern of securing welds 38 across the outer circumferential surface 40 of the anvil 32. During a first step 222 of the method 220, an intermediate product 224 is formed by oscillating the horn 34B between raised and lowered positions in the manner described with respect to step 204 of the method 182 ( FIG. 22 ) to create a bond-free area 226. In step 228, the knife(s) 190 sever one or more of the elastic yarns 18 to form one or more inactive zones 88 in the resulting intermediate product 230. In step 232, the second anvil 160 forms one or more laminate bonds within the inactive zones 88 to complete the elastic composite structure 138.

[0092] Advantageously, method 220 can be implemented to produce different size final products without tooling changes by controlling the time intervals that the vibrating horn 34B is held in the raised and lowered positions during step 222, and by controlling the web speed relative to the rotational speed of the second anvil 160 during step 232. More specifically, the vibrating horn 34B is held in the raised position for longer time intervals for larger size products relative to smaller size products to produce longer bond-free regions 226. During step 232, the relative speed of the web to the anvil is controlled to form a laminate bond pattern that extends the resulting bond-free region 226 by a desired amount.

[0093] 26, 27, and 28 are exemplary planarized representations of respective faces of the first anvil 32, knife unit 186 (of the cutting unit 184—FIG. 1), and second anvil 160 according to another embodiment in which the first anvil 32, knife unit 186, and second anvil 160 are arranged in the tandem arrangement shown in FIG. 1 and operated according to the method of producing the resilient composite structure 138 shown in FIG. 29. The first anvil 32 includes a first pattern 234 of protrusions including the secure weld lines 122 that create the secure joint line 134 of FIG. 29. In the illustrated embodiment, the knife unit 186 includes two knives 190 oriented at an angle relative to the axis of rotation of the knife unit 186. In such a case, the corresponding anvil insert 194 (FIG. 24) may be arranged at a similar angle relative to the axis of rotation of the rotating anvil 188 (FIG. 24). The knife 190 of the knife unit 186 cuts the elastic yarn 18 to form the inactive zone 88 of the elastic composite structure 138. The second anvil 160 (FIG. 28) includes a second pattern of protrusions 236 having a series of lamination weld lines 130 that form a series of lamination bond lines 136 (FIG. 29) within the inactive zone 88.

[0094] FIG. 30 illustrates a bonding apparatus 238 that may be used in manufacturing line 10 in place of bonding apparatus 22 to create an elastic composite structure 240 as shown in FIG. 31. In one embodiment, bonding apparatus 238 includes a horn 34 as described above and an anvil 32 including at least one break bar 242 that spans the length of the pattern of secure welds 38 on the anvil 32, similar to break bar 46 (FIG. 2), or that spans only a portion of the entire length, similar to break bar 128 (FIG. 10). First and second web layers 12, 16 and one or more tensioning elastic yarns 18 are oriented onto face 40 of anvil 32 and into gap 66 between anvil 32 and horn 34 by either a common guide roller 244 or multiple rollers similar to that shown in FIG. 3. As one or more elastic yarns 18 pass between break bar 242 and horn 34, the yarn(s) 18 are severed. Immediately after cutting, the tensioning device 246 increases the tension on the cutting yarn(s) 18 so that the cutting yarn(s) 18 are pulled backward (upstream) across the face 40 of the anvil 32 toward the common guide roller 244. Friction between the cut elastic yarn(s) 18 and the first and second web layers 12, 16 prevents the cut elastic yarn(s) 18 from retracting to a position upstream of the guide roller(s) 244. Once the cutting yarn(s) 18 have retracted through the tensioning device 246 a distance equal to the desired length 248 of the inactive zone 88, the anvil 32 continues to rotate in the direction 250, forming a secure joint 82 fusing the first and second web layers 12, 16 together as the horn 34 engages the secure weld 38 on the face 40 of the anvil 32. The inactive zone 88 shown in FIG. 31 is formed during the period when the tensioning device 246 holds the cutting yarn(s) 18 in the retracted position.

[0095] After a predetermined period of time during which the cut yarn(s) 18 are retracted to the trailing edge of the inactive zone 88, the tensioning device 246 adjusts the tension of the cut elastic yarn(s) 18 back to its original tensioned state, causing the cut elastic yarn(s) 18 to resume movement downstream toward the horn 34. After the severed end(s) of the cut elastic yarn(s) 18 reach the horn 34, they are effectively rethreaded and secured in place relative to the first and second web layers 12, 16 by the subsequently formed securement joints.

[0096] In an alternative embodiment, the horn 34 is replaced by a cutting knife(s), e.g., cutting unit 184 of FIG. 24 , with the horn 252 positioned downstream of the cutting knife. One or more elastic yarns 18 are severed using the cutting knife and then slid back toward the guide roller(s) 244 by the tensioning device 246 in a manner similar to that described above. Once the cut elastic yarn(s) 18 have slipped a distance equal to the desired inactive zone length, the tensioning device 246 adjusts the tension of the cut elastic yarn(s) 18 so that the cut elastic yarn(s) 18 resume movement across the anvil face 40 between the first and second web layers 12, 16. The interaction between the horn 252 and the secure weld 38 creates a secure joint 82 on the resulting elastic composite structure 240.

[0097] In yet another alternative embodiment, tensioning device 246 is omitted, and guide roller 244 is replaced with an eccentric roller tensioner (not shown) that rotates to increase or decrease the tension in composite web / yarn assembly 30 according to a timing pattern that synchronizes when elastic yarn(s) 18 break. More specifically, the eccentric roller tensioner is controlled to decrease the tension in composite web / yarn assembly 30 when or shortly after elastic yarn(s) 18 break. Decreasing the tension in composite web / yarn assembly 30 decreases friction between the broken elastic yarn(s) 18 and the first and second web layers 12, 16, thereby allowing the broken elastic yarn(s) 18 to snap back toward the eccentric roller tensioner. Once the cut elastic yarn(s) 18 have slipped a distance equal to the desired inactive zone length, the eccentric roller tensioner is controlled to rotate to increase tension in the composite web / yarn assembly 30, thereby increasing friction between the cut elastic yarn(s) 18 and the first and second web layers 12, 16. The increased friction causes the cut elastic yarn(s) 18 to resume traveling with the first and second web layers 12, 16 across the anvil face 40. An inactive zone 88 ( FIG. 31 ), free of the elastic yarn(s) 18 but including junctions spaced at a distance similar to the fixed junctions 82, is formed on the resulting elastic composite structure 240 during the time interval between when the cut elastic yarn(s) 18 are cut and when they are subsequently rethreaded.

[0098] The apparatus and methods described herein can be used to create elastic composite structures in the waist, under-waist, and / or leg cuff regions of one-piece or three-piece diapers, by way of non-limiting example, without the use of glue. By eliminating the use of glue, the resulting elastic composite is softer to the touch and has a more uniform ripple pattern in the cross-machine direction. The apparatus and methods described herein also provide various means for forming distinct elastic (i.e., anchored) and inelastic (i.e., inert) zones in the resulting elastic composite without creating cuts or slits in the web layers. Thus, the embodiments of the invention disclosed herein enable a manufacturing process that creates a final product that is structurally more robust than prior art approaches and that is visually and tactilely more pleasing to the end customer.

[0099] Thus, according to one embodiment of the present invention, a joining apparatus for manufacturing an elastic composite structure having at least one elastic yarn secured between a pair of opposing web layers is disclosed. The joining apparatus includes a rotary anvil having a surface with a weld pattern including at least one anchoring region and at least one passivation region. The at least one anchoring region includes a plurality of anchoring welds configured to fuse the pair of opposing web layers together and form a secure joint that secures the at least one elastic yarn in place relative to the pair of opposing web layers. The at least one passivation region includes a break bar configured to sever the at least one elastic yarn.

[0100] According to another embodiment of the present invention, a method of manufacturing an elastic composite structure includes disposing tensioned elastic yarns between a first web layer and a second web layer, and fusing the first web layer to the second web layer to form an anchoring zone comprising a plurality of discrete anchoring joints fusing the first web layer to the second web layer and securing the tensioned elastic yarns therebetween. The method also includes cutting the tensioned elastic yarns to form an inactive zone of the elastic composite structure free of the tensioned elastic yarns, the inactive zone being located between adjacent portions of the anchoring zone. The method further includes fusing the first web layer to the second web layer within the inactive zone.

[0101] According to yet another embodiment of the present invention, an elastic composite structure includes a tensioning elastic yarn, a first web layer disposed on a first side of the tensioning elastic yarn, a second web layer disposed on a second side of the tensioning elastic yarn, and a pattern of bonds fusing the first web layer to the second web layer. The bond pattern includes an inactive zone including at least one bond pattern, a cut end of a first portion of the tensioning elastic yarn, and a cut end of a second portion of the tensioning elastic yarn. The inactive zone is free of tensioning elastic yarn. The bond pattern also includes anchoring zones separating opposite ends of the inactive zone. The anchoring zone includes a first plurality of bonds in the bond pattern that secure the first portion of the tensioning elastic yarn to the first and second web layers and a second plurality of bonds in the bond pattern that secure the second portion of the tensioning elastic yarn to second portions of the first and second web layers.

[0102] While the present invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions, or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it should be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the present invention should not be deemed limited by the above description, but is limited only by the appended claims.

Claims

1. A joining device, comprising: a rotary anvil that rotates around a rotation axis; The rotating anvil a plurality of fixation protrusions disposed in a fixation region of the rotary anvil, the fixation protrusions being constructed such that adjacent fixation protrusions fuse a pair of opposing web layers together at pairs of adjacent fixation joints that fix an elastic thread passing between the adjacent fixation joints in position relative to the pair of opposing web layers, the fixation protrusions being arranged in a plurality of fixation weld lines spaced along a circumferential axis of a face of the rotary anvil; a continuous welding projection extending outward from a face of the rotary anvil in a passivated area of ​​the rotary anvil, the continuous welding projection simultaneously severing the elastic yarn and forming an unbroken bond pattern to fuse the pair of opposing web layers together; the passivation region extends across a portion of the entire width of the rotary anvil along the rotation axis, and the continuous weld projection extends in a direction of a circumferential axis of the face of the rotary anvil so as to extend across the plurality of fixed weld lines.

2. The joining apparatus of claim 1 , further comprising a horn having an action surface spaced apart from an action surface of the continuous weld projection and spaced apart from land surfaces of the plurality of fixation projections.

3. 3. The joining apparatus of claim 2, further comprising a mechanical camshaft assembly coupled to the horn, the mechanical camshaft assembly configured to oscillate the horn between a lowered position in which the horn communicates with the rotary anvil to form a fixed joint, and a raised position in which the horn is spaced apart from the rotary anvil a distance that prevents the formation of a fixed joint.

4. 2. The joining device of claim 1, further comprising a tensioning device configured to selectively repel the elastic yarn severed by the continuous welding projection back in an upstream direction relative to the downstream movement of the pair of opposing web layers, and resume downstream movement between the pair of opposing web layers after a predetermined period of time.

Images