Improved Method and Apparatus for Ultrasonic Bonding

Abstract

To provide a system and method for controlling the speed of both a continuous web and a bonding apparatus in order to effectuate stronger bonds in the web.SOLUTION: A bonding system 10 includes: a velocity changing device for increasing and decreasing a velocity of a web 12 in a machine direction; anvils 14A, 14B and corresponding ultrasonic horns 16A, 16B that interact to form ultrasonic bonds on the web; and an anvil actuator configured to control a movement of the anvils. A control system 56 is also included in the bonding system for controlling operation of anvil actuators 52A, 52B, and the velocity changing device, with the control system programmed to decrease a moving velocity of the web from a feed velocity to a bonding velocity as the web passes between the anvils and the ultrasonic horns and control movement of the anvils to synchronize the movement of the anvils with the moving velocity of the web.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to disposable hygiene products, and more specifically, to a method and apparatus for treating disposable hygiene products such as baby diapers, adult diapers, disposable underwear, incontinence products, sanitary napkins, etc. More specifically, the present invention relates to controlling and arranging webs or web portions of disposable diapers and bonding (welding, adhering) them. Various types of automatic manufacturing apparatuses have been developed to produce desired end products with diverse materials and structures.

Background Art

[0002] The present invention disclosed herein relates to a method for controlling elements moving on a manufacturing line, and more specifically, to a bonding system for bonding a plurality of webs. Although the description here relates to diaper manufacturing, the method can be easily adapted to other applications. Although the description here relates to the bonding portion of diapers, the method can be easily adapted to other products, other disposable products, other types of diapers, and other parts of diapers.

[0003] In the manufacture of disposable hygiene products such as diapers, different layers of material, such as two layers of a continuously moving substrate web material, are bonded by compressing the web through a bonding device such as an ultrasonic welding system. The ultrasonic welding system includes an ultrasonic horn and an anvil roll separated by a gap, through which the web material passes in a compressed state, whereby it is recognized that the welding system is a rotary ultrasonic welding system or a blade-type ultrasonic welding system. Typically, the anvil roll includes one or more arrays of raised protrusions configured to bond the web in a predetermined bonding pattern using an ultrasonic horn capable of generating ultrasonic energy on the bonding surface to ultrasonically bond the web as it moves between the ultrasonic horn and the anvil roll. The rotary anvil and the ultrasonic horn cooperate with each other to ultrasonically bond the web layers to each other. During the bonding process, the web layers are exposed to ultrasonic radiation from the horn that increases the vibration of the particles of the web layer. The ultrasonic radiation or ultrasonic energy is focused at specific bonding points where frictional heat fuses the multiple web layers without the need for a consumable adhesive.

[0004] The consistency and quality of ultrasonic bonding depend on the consistency of the force applied to the web by the combination of the anvil roll and the bonding roll, and in particular on the speed of operation, the time during which the web is pressed in the compression nip (i.e., the dwell time), and the type of material being bonded. Also, the consistency and quality of bonding depend on the frequency and amplitude of the vibration of the ultrasonic horn. Of these variables, the dwell time is a major factor that must be properly controlled to form a bond of sufficient quality. Typically, when forming a bond, controlling only the web speed while controlling the web speed to increase the dwell time is not sufficient to form a bond of the desired quality.

[0005] Accordingly, there is a need for an improved apparatus and method for performing bonding on at least one continuously moving web using a bonding apparatus. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] According to one aspect of the present invention, a system for bonding a web comprising at least a pair of web layers includes a speed changing device for increasing or decreasing the speed of the web in the (machine) processing direction, an anvil and a corresponding ultrasonic horn that interact to form an ultrasonic bonding portion on the web, and an anvil actuator configured to control the operation of the anvil. Further, the control system includes an anvil actuator and a bonding system for controlling the operation of the speed changing device, and the control system is programmed to control the operation of the anvil so as to reduce the moving speed of the web from the feed speed to the bonding speed and synchronize the operation of the anvil with the moving speed of the web when the web passes between the anvil and the ultrasonic horn.

[0007] According to another aspect of the present invention, a method for bonding a web having at least a pair of web layers includes moving the web in the processing direction through a feed assembly, the feed assembly being configured to selectively control the speed of the web. The method further includes feeding the web to one or more bonding devices, each of the one or more bonding devices including an anvil, an ultrasonic horn that interacts with the anvil to form an ultrasonic bonding portion on the web, and an anvil actuator configured to control the speed of the anvil. The method further includes controlling the operation of the anvil actuator and the feed assembly to synchronize the speed of the web with the speed of the anvil by reducing the speed of the web and the speed of the anvil to the web bonding speed and the anvil bonding speed when the web passes between the anvil and the ultrasonic horn.

[0008] These and other advantages and features will be more readily understood from the following detailed description of the preferred embodiments of the present invention, provided in connection with the accompanying drawings.

Brief Description of the Drawings

[0009] The drawings illustrate embodiments contemplated for practicing the present invention.

[0010] In the drawings,

[0011]

Figure 1

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Figure 2

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Figure 3

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Figure 4A

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Figure 4B

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Figure 5A

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Figure 5B

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Figure 5C

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Figure 6A

Figure 6B

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Figure 7

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Figure 8A

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Figure 8B

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Figure 9

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Figure 10

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Figure 11

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Figure 12

[0027]

Figure 13

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Figure 14

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Figure 15

[0030]

Figure 16

[0031]

Figure 17

[0032]

Figure 18

DETAILED DESCRIPTION OF THE INVENTION

[0033] Embodiments of the present invention provide a method and apparatus for controlling the speeds of both a continuous web and a bonding apparatus to achieve stronger bonding on the web, including synchronizing and / or coordinating these speeds at a desired bonding time. Further, embodiments of the present invention provide a method and apparatus for selectively controlling the distance between a selected anvil-horn combination and one or more adjacent anvil-horn combinations.

[0034] Referring to FIGS. 1 and 2, a bonding system 10 according to an embodiment of the present invention is disclosed. Embodiments of the present invention are configured to bond a material web 12, which is formed from a first web layer 12A and a second web layer 12B (described below) or from a folded single web structure. The system 10 includes a first anvil 14A, a second anvil 14B, a first ultrasonic horn 16A, and a second ultrasonic horn 16B. The first anvil 14A and the second anvil 14B are horizontally spaced apart by a predetermined distance d1 in a row and in the processing direction 16. The system also includes conveying means 18 for conveying the web 12, whereby the web 12 passes through a first gap between the first anvil 14A and the first ultrasonic horn 16A and then through a second gap between the second anvil 14B and the second ultrasonic horn 16B. As shown, for example, in FIG. 3, to bond each portion of the web 12, the first ultrasonic horn 16A and the second ultrasonic horn 16B simultaneously apply vibrational energy to the web 12 and function in cooperation with the anvils 14A, 14B.

[0035] System 10 further includes a speed changing device that increases or decreases the moving speed of web 12. In the illustrated embodiment, the speed changing device includes a first web festoon accumulator 20A having a first accumulator roller 22A and a second web festoon accumulator 20B having a second accumulator roller 22B. The first web festoon accumulator 20A receives the web 12 flowing from the upstream side and releases the web in the direction of ultrasonic horns 16A, 16B. On the other hand, the second web festoon accumulator 20B receives the web 12 from the ultrasonic horns 16A, 16B and moves the web 12 downstream. The speed changing device further includes means for synchronously and linearly moving the first accumulator roller 22A and the second accumulator roller 22B, thereby changing the speed V of the received web 12. When the first accumulator roller 22A and the second accumulator roller 22B move in the direction of arrow A, the speed V1 of the web 12 from the upstream shifts to a lower second speed V2, and during the bonding process, the residence time of the web 12 becomes a time suitable for proper bonding. The anvil rolls 14A, 14B are preferably synchronized so that the system performs two bondings simultaneously while at a lower speed V2. When the web 12 is bonded, the first accumulator roller 22A and the second accumulator roller 22B move in a direction opposite to arrow A, and the web 12 moves at a speed V3 and is finally transported downstream at a first speed V1 by the second web festoon accumulator 20B. In another embodiment, the speed changing device may be a vertical accumulator system or a horizontal accumulator system, and either of them may include any number of roll assemblies that selectively control the speed of the web 12.

[0036] Referring to FIGS. 4A, 4B, 5A, 5B, and 5C, further details regarding anvils 14A, 14B according to the present invention are provided. The anvils 14A, 14B may each comprise an anvil insert 24 having a predefined shape. The anvil inserts 24 shown in these figures include a pair of seal surfaces 26 separated by a gap having a recess 28 therebetween, and the seal surfaces 26 are provided with a continuous rectangular pattern, i.e., teeth 32, on their surfaces. The inclined orientation of the rectangular pattern 32 provides coverage of both the trailing and leading edges in a direction intersecting the machining direction. This configuration enables even wear of the horns 16A, 16B that interact with the anvils 14A, 14B, significantly reducing the need for regrinding of the worn horns 16A, 16B and reducing the downtime for maintenance of the horns 16A, 16B. Referring particularly to FIGS. 5B and 5C, the inclined arrangement of the rectangles or teeth 32 creates a bonding pattern that will wear the corresponding ultrasonic horns 16A, 16B evenly. The ends 34 of adjacent teeth 32 are parallel to each other and are inclined at a predetermined angle 36° with respect to the machining direction (FIG. 5B). This angle 36° provides the next tooth 32 to fill the gap G (FIG. 5C) that exists between the preceding teeth 32. Depending on the shape, such as the gap width between rows of teeth 32 or the gap width between teeth 32, the predetermined angle 36° may provide complete coverage of the ultrasonic horns 16A, 16B to achieve the purpose of even wear. The anvil insert 24 in this drawing may be used to bond the ends 38 of adjacent articles simultaneously with the bonding portion 40 in a direction intersecting the machining direction while securing the boundary between the sealing ends for a subsequent cutting operation.

[0037] Another embodiment of the anvil insert A is illustrated in FIGS. 7, 8A, and 8B. The anvil insert 42 includes a seal surface 44 having a plurality of raised seal regions 46 arranged in a pattern inclined at an angle 48° from the machining direction. Alternatively, as shown in FIG. 9, the pattern shown in FIGS. 8A and 8B may be applied to the entire surface of the anvils 14A, 14B.

[0038] Figure 10 shows another configuration of the anvil and the ultrasonic horn. In this embodiment, instead of the single anvils 14A and 14B shown in the previous drawings, a pair of anvils 14A1, 14A2 and 14B1, 14B2 are used. The pair of ultrasonic horns 16A1, 16A2, and 16B1, 16B2 correspond to the pair of anvils 14A1, 14A2 and 14B1, 14B2 and cooperate with the pair of anvils 14A1, 14A2 and 14B1, 14B2.

[0039] Referring again to FIGS. 1 and 2, the predetermined distance d1 between the first anvil 14A and the second anvil 14B may be controlled to define the distance between the resulting bonding portions 40 on the web 12 (FIGS. 6A, 6B), and the resulting bonding portions 40 are located at positions that will be the ends 38 of the individual finished products. Since the distance d1 corresponds to the length of the individual articles, the desired distance d1 may be varied to accommodate finished products of various sizes. Thus, the length of the individual articles may be varied by adjusting the position of the first or second ultrasonic horn 16A, 16B relative to the other ultrasonic horns 16A, 16B.

[0040] As shown in FIGS. 1 and 2, the system 10 changes the distance between the selected anvils 14A, 14B and ultrasonic horns 16A, 16B and the adjacent anvils 14A, 14B and ultrasonic horns 16A, 16B (e.g., changes the distance from d1 to d2) through the operation of a device for the relative linear reciprocating motion of the other anvils 14A, 14B and ultrasonic horns 16A, 16B, and is configured to move in the direction of arrow B using a drive device 50 such as, for example, an electric motor, a pneumatic actuator, or a hydraulic actuator, and a related linear actuator 52 that provides linear reciprocating motion in the embodiments of FIGS. 1 and 2 (see FIG. 2). The combination of the selected anvils 14A, 14B and ultrasonic horns 16A, 16B is preferably slidably attached to the lower structure 54 so as to move linearly. Since the distance between the bonding positions d1 and d2 can be changed by changing the positions of the first ultrasonic horn 16A and the second ultrasonic horn 16B, the present system can easily manufacture individual articles of various sizes. FIG. 2 shows the operation of the second ultrasonic horn 16B, but depending on the requirements of a particular application, the position of the first ultrasonic horn 16A may also be changed, or alternatively, the second ultrasonic horn 16B may be replaced.

[0041] According to one embodiment, the selected anvils 14A, 14B and ultrasonic horns 16A, 16B, and the distances d1, d2 between adjacent anvils 14A, 14B and ultrasonic horns 16A, 16B may be controlled via a closed-loop control system 56. To linearly move the desired pairs of anvils and horns 14A, 14B, 16A, 16B along the lower structure 54, the control system 56 may operate one or more electric motors 50A, 50B in conjunction with a vision (video) system (e.g., a camera) 58 that provides inputs to the control system 56 regarding the positioning / gap setting of the pairs of anvils and horns 14A, 14B, 16A, 16B. During operation, the vision system 58 acquires images of the bonding system 10, specifically, images of the positioning of the anvils 14A, 14B and horns 16A, 16B on the lower structure 54. The vision system 58 provides these images as inputs to the control system 56, and the control system 56 may internally include a processor 60 that analyzes the images to determine the gaps between the anvils 14A, 14B and horns 16A, 16B. Next, the processor 60 compares the gap between the pairs of anvils 14A, 14B and horns 16A, 16B with a predetermined desired gap (set based on the size of the finished product and the gap / position of the bonding portions formed on the product) between the paired anvils and horns. If the gap between the pairs of anvils 14A, 14B and horns 16A, 16B measured from the images acquired by the vision system 58 is the same as the predetermined desired gap, the positions of the pairs of anvils 14A, 14B and horns 16A, 16B are not changed. Conversely, if the gap between the pairs of anvils 14A, 14B and horns 16A, 16B is different from the predetermined desired gap, the positioning of the pairs of anvils 14A, 14B and horns 16A, 16B is changed to adjust that gap. When changing one or more of the pairs of anvils 14A, 14B and horns 16A, 16B, the control system 56 operates the associated linear actuators on one or more electric motors 50A, 50B to linearly move or slide the pairs of anvils 14A, 14B, and horns 16A, 16B along the lower structure 54.When the positioning of the anvils 14A, 14B and the horns 16A, 16B pairs is changed, continuous feedback may be obtained from the vision system 58 until it is determined that the gap between the anvils 14A, 14B and the horns 16A, 16B pairs has matched a predetermined desired gap, at which time the time activation of the electric motors 50A, 50B is interrupted. According to an embodiment of the present invention, the closed-loop control system 56 described above provides adjustment of the distances d1, d2 between the combinations of the anvils 14A, 14B and the horns 16A, 16B at the time of startup of the system 10 and / or during the operation of the system 10.

[0042] In another embodiment other than closed-loop control, the vision system 58 may operate such that the operator manually changes the positioning to obtain an image of the positioning of the anvils 14A, 14B and the horns 16A, 16B pairs to be used later. That is, the vision system 58 provides an image to the processor 60, and the processor 60 analyzes the screen to determine the gap between the anvils 14A, 14B and the horns 16A, 16B pairs, and then provides the determined gap as an output to the operator, such as the display of a numerical output. The operator may then manually control one or more electric motors 50A, 50B to operate the associated linear actuators 52A, 52B to linearly move or slide the anvils 14A, 14B and the horns 16A, 16B pairs along the lower structure to control the gap between the anvils 14A, 14B and the horns 16A, 16B pairs. As an example, the operator may change the positioning of the anvils 14A, 14B and the horns 16A, 16B pairs using the + / − buttons included in the control system 56. In this way, the positioning of the anvils 14A, 14B and the horns 16A, 16B pairs may be incrementally adjusted until it is determined that the gap between the anvils 14A, 14B and the horns 16A, 16B pairs matches a predetermined desired gap by the vision system 58 / control system 56.

[0043] Referring to FIGS. 11 and 12, another embodiment of the bonding system 10 additionally includes a third anvil 14C, which is provided with an anvil insert 24 having the above-described predetermined characteristics and a third ultrasonic horn 16C. The anvils 14A, 14B, 14C are arranged in a row in the processing direction 16 and are laterally spaced apart. In the previous embodiment, the ultrasonic horns 16A, 16B, 16C simultaneously apply vibrational energy to the web 12 in cooperation with each of the anvils 14A, 14B, 14C to bond each portion of the web 12 that will become the end 38 of the individual finished product 12 (FIGS. 6A, 6B). The anvils 14A, 14B, 14C and the corresponding horns 16A, 16B, 16C are spaced apart by a predetermined distance d3 corresponding to the distance between the bonding portions 40 of the finished product 12 (FIGS. 6A, 6B). Thus, the length of the individual product may be changed by adjusting the positions of the first ultrasonic horn 16A, the second ultrasonic horn 16B, and the third ultrasonic horn 16C with respect to the first ultrasonic horn 16A, the second ultrasonic horn 16B, and the third ultrasonic horn 16C. The bonding system 10 may include a combination of fixed and movable ultrasonic horns 16A, 16B, 16C. For example, by way of non-limiting example, one fixed ultrasonic horn and two movable ultrasonic horns, two fixed ultrasonic horns and one movable ultrasonic horn, and three fixed ultrasonic horns and three movable ultrasonic horns may be mentioned.

[0044] Using the possible combinations of the above-described fixed and movable ultrasonic horns 16A, 16B, 16C, one or more selected anvils 14A, 14B, 14C and horns 16A, 16B, 16C may perform a linear reciprocating motion with respect to another anvil 14A, 14B, 14C and horns 16A, 16B, 16C, as indicated by arrow D, thereby changing the distance between the selected anvils 14A, 14B, 14C and horns 16A, 16B, 16C and the adjacent anvils 14A, 14B, 14C and horns 16A, 16B, 16C from d3 to d4 (FIG. 12). Such movement of the anvils 14A, 14B, 14C and horns 16A, 16B, 16C may be controlled via the operation of the electric motor 50 and the associated linear actuator 52 by the control system 52, similar to the above-described method with respect to FIGS. 1 and 2.

[0045] Referring to FIG. 13, a bonding system 62 according to another embodiment is illustrated in which the movement (e.g., rotational speed / velocity) of the anvil is selectively controlled to be synchronized with the speed of the web in order to control the dwell time of the anvil on the web. In connection with ultrasonic bonding systems and ultrasonic bonding techniques using a combination of an anvil and an ultrasonic horn, system 62 (and its operating techniques) are described, but it is contemplated that the following systems / techniques may be extended to other thermal bonding or crimping systems that use an anvil for bonding on a moving web. For example, bonding systems that form a pressure weld through the interaction of a patterned anvil and a smooth roller (instead of an ultrasonic horn) and the use of active or passive thermal heating are considered to be within the scope of the present invention. Further, with respect to the control of a bonding system using two bonding devices (i.e., a horn / anvil combination), system 62 is described below, but system 62 may be implemented with two or more bonding devices or with only one bonding device.

[0046] As shown in FIG. 13, a web of material 64 (formed from a first web layer 64A and a second web layer 64B (described later), or from a folded single web structure) is fed in the processing direction 66. The layers of the web 64 are made of materials that are mutually soluble in the application of applied energy that softens or melts and bonds either or both of the layers 64A, 64B without using an intermediate layer of an adhesive material such as glue. The opposing pair of web layers 64A, 64B may be of the same type of material, but in another embodiment may be of different materials. By way of non-limiting example, the first web layer 64A and the second web layer 64B may be nonwoven materials, woven materials, thin films, foams, and / or composite or laminated materials of any of these material types.

[0047] Bonding system 62 includes a variable speed feed assembly 68 (or more generally, a "variable speed device") that feeds web 12 to one or more bonding devices and controls its speed. Although it is recognized that system 62 may include only a single bonding device, for example, in FIG. 13, one or more bonding devices are used as two bonding devices 70A, 70B. The variable speed device 68 operates to accelerate and decelerate the moving speed of web 64. Although a web festoon accumulator is specifically illustrated in FIG. 13, it is recognized that the variable speed device may comprise either a web festoon accumulator, a vertical accumulator series, or a horizontal accumulator series. According to the illustrated embodiment, the variable speed device 68 has a first web festoon accumulator 72A having a first accumulator roller 74A and a second web festoon accumulator 72B having a second accumulator roller 74B. The first web festoon accumulator 72A receives the incoming web 64 from upstream and releases the web towards the bonding devices 70A, 70B, while the second web festoon accumulator 72B receives the web 64 from the bonding devices 70A, 70B and moves the web 64 downstream. The variable speed device 68 further includes means (e.g., a linear actuator 88) for synchronously moving the first accumulator roller 74A and the second accumulator roller 74B in a linear direction to change the speed of the web 64 received at an initial speed V1 (i.e., "feed speed"). Specifically, the gap between the first accumulator roller 74A and the second accumulator roller 74B may be adjusted to change to a slower second speed V2 (i.e., the bonding speed) for performing the bonding of the web 64 such that the dwell time of the web 64 during the bonding process is sufficient for proper bonding.Before being conveyed again by the second web festoon accumulator 72B at the first speed, when the web 64 is bonded, the gap between the first accumulator roller 74A and the second accumulator roller 74B may be adjusted to change the speed to speed V3.

[0048] The bonding devices 70A, 70B of the bonding system 62 may be known ultrasonic welding systems in alternative embodiments and, by way of non-limiting example, include rotary ultrasonic welding systems or blade ultrasonic welding systems. In the illustrated embodiment, the bonding devices 70A, 70B each include a rotary anvil 76A, 76B and ultrasonic stationary blade horns 78A, 78B, also known as sonotrodes, which cooperate with each other to bond (i.e., fuse) a first web layer 64A to a second web layer 64B. In another embodiment, a plurality of stationary blade horns, or one or more rotary horns, may be included. A motor (not shown) that drives the ultrasonic horns 78A, 78B, and a vibration control unit (not shown) that adds ultrasonic energy to the horns 78A, 78B to vibrate the horns are also included in the bonding devices, and further, anvil actuators 80A, 80B operatively coupled to the anvils 76A, 76B are also included to drive the anvils 76A, 76B. According to one embodiment, the anvil actuators 80A, 80B may be configured as servo motors (and thus are hereinafter referred to as "servo motors 80A, 80B"), but it is recognized that the anvil actuators 80A, 80B may be any suitable device that activates the anvils 76A, 76B. The horns 78A, 78B and the anvils 76A, 76B of each bonding device 70A, 70B are positioned relative to each other with a gap therebetween to facilitate ultrasonic bonding of the first web layer 64A and the second web layer 64B to each other. During the bonding process, the web layers 64A and 64 are exposed to ultrasonic radiation from the horns 78A, 78B that increases the vibration of the particles in the web layers 64A and 64B. The ultrasonic radiation or ultrasonic energy is focused at specific bonding points where frictional heat fuses the web layers 64A and 64B without the need for a consumable adhesive.

[0049] According to an embodiment of the present invention, a bonding system 62 that functions to control the operations of bonding devices 70A, 70B, and a speed changing device 68 includes a control system 82. The control system 82 may include a programmable logic controller 84 operably connected to the bonding devices 70A, 70B, and the speed changing device 68 via wired or wireless communication for communicating signals (inputs, control signals, etc.) with each other. The programmable logic controller 84 includes one or more processors 86 for processing data acquired during the operations of the bonding devices 70A, 70B, and / or generating command signals for controlling the operations of the bonding devices 70A, 70B, and the speed changing device 68.

[0050] The control system 82 is in an operable communication state with the device changing device 68 to selectively control the speed of the web 64 when the web 64 is supplied from the speed changing device 68 to the bonding devices 70A, 70B. In one embodiment, the control system 82 is in an operable communication state with a linear actuator 88 of a web festoon accumulator where the first accumulator roller 74A and the second accumulator roller 74B are located, so as to control the speed of the web 64 by selectively controlling the operation of the linear actuator 88. As described above, the first accumulator roller 74A and the second accumulator roller 74B may be moved to change the speed of the web 64 from an initial speed V1 to a lower second speed V2 during bonding of the web 64, and to a speed V3 before the web 64 is bonded and moved again by the second web festoon accumulator 72B at the first speed V1.

[0051] In addition, the control system 82 is in an operable communication state with the bonding devices 70A and 70B. This is for the purpose of selectively controlling a motor (not shown) that drives the ultrasonic horns 78A and 78B, and a vibration control unit (not shown) that supplies energy to the horns 78A and 78B with ultrasonic waves to vibrate the horns 78A and 78B, and further controlling the servo motors 80A and 80B that drive the anvils 76A and 76B. Regarding the control of the servo motors 80A and 80B that drive the anvils 76A and 76B, the control system 82 transmits a control signal to the servo motors 80A and 80B, and controls the operation of the anvils 76A and 76B by setting, for example, the rotational speed or velocity of the rotary anvils 76A and 76B in the embodiment of FIG. 13. The velocity may be changed so as to affect the residence time of the anvils 76A and 76B (i.e., the anvil insertion portion 90 that can be configured as the insertion portion 24 shown in FIGS. 4A, 4B, 5A, 5B, and 5C, for example) with respect to the web 64. For example, during the bonding process, the rotational speed of the anvils 14A and 14B is changed so that the rotational speed of the anvils 14A and 14B from the upstream side is decreased to a lower second speed so that the residence time of the web 64 is sufficient for proper bonding. When the web 64 is bonded, the anvils 14A and 14B accelerate by increasing the speed and rotate back in the downstream direction at the first speed.

[0052] According to an exemplary embodiment, the control system 82 controls the operations of the speed changing device 68 and the bonding devices 70A, 70B such that the speed of the web 64 is synchronized with the speed of the anvils 76A, 76B. That is, the control system 82 controls the operations of the speed changing device 68 and the bonding devices 70A, 70B such that an increase in the speed of the web 64 corresponds to an increase in the speed of the anvils 76A, 76B, and similarly, a decrease in the speed of the web 64 corresponds to a decrease in the speed of the anvils 76A, 76B. By synchronizing the speed of the web 64 with the speed of the anvils 76A, 76B, the residence time of the anvils 76A, 76B with respect to the web 64 is selectively controlled, and for example, the residence time is maximized when desired. By controlling the residence time of the anvils 76A, 76B with respect to the web 64, it becomes possible to form a bonding portion of a desired length (in the processing direction 66) on the web 64, and at that time, the bonding length can be selectively controlled based on the product type / size, the web material, and the strength of the required bonding portion. Returning to FIGS. 6A and 6B, the bonding portion 40 is shown in more detail, and in the enlarged view of FIG. 6B, it can be seen that the bonding portion has a length 92 in the processing direction 66. As described above, since the length 92 of each bonding portion 40 in the bonding pattern is determined at least in part by the speed of the web 64 and the speed of the anvils 76A, 76B, it may be selectively controlled based on the residence time of the anvils 76A, 76B with respect to the web 64. Further, by changing the length 92 of the adjacent bonding portions 40, the gap 94 between the bonding portions 40 can also be selectively controlled. According to an embodiment, the length 92 of the bonding portion 40 and / or the gap 94 between the bonding portions 40 can be changed by up to 25% by controlling the residence time of the anvils 76A, 76B with respect to the web 64.

[0053] Figures 14 - 16 illustrate the speed characteristics of web 64 and anvils 76A, 76B controlled by control system 82, which controls speed changer 68 and anvils 76A, 76B to synchronize the speeds of web 64 and anvils 76A, 76B. According to an exemplary embodiment, web speed 96 and anvil (rotational) speed 98 are controlled to have sinusoidal characteristics, and the speeds of web 64 and anvils 76A, 76B are the web bonding speed V W 2 and anvil bonding speed V A 2 shown as the bonding speed / velocity. However, although the characteristics of web speed 96 and anvil speed 98 are depicted as sine curves in FIGS. 14 - 16, in other embodiments, either or both of the speed characteristics may have triangular, sawtooth, or other non - sinusoidal characteristics.

[0054] As shown in FIG. 14, in one embodiment, web speed 96 and anvil speed 98 are synchronized with each other, but during bonding time 100 when forming a bonding portion on web 64, the speeds of web 64 and anvils 76A, 76B are not equal to each other. That is, control system 82 controls speed changer 68 and servo motors 80A, 80B such that web 64 is moved at a bonding speed V A 2 greater than the anvil bonding speed V W 2 at which anvils 76A, 76B rotate. The magnitude of the speed mismatch between the web bonding speed V W 2 and anvil bonding speed V A 2 shown at 102 (partially) determines the bonding length formed on web 64. This length affects the dwell time of the web on the anvil, and the magnitude of this speed mismatch 102 may be selectively controlled by the operator to control the bonding length.

[0055] Referring to FIG. 15, during the bonding time 100, the sizes of the bonding portions are equal or approximately equal (e.g., + / - 5%). When forming the bonding portions on the web 64, during the bonding time 100, the speeds / velocities of the web 64 and the anvils 76A, 76B are synchronized according to an embodiment, and the speed characteristics of the web 64 and the anvils 76A, 76B are shown. In other words, the speed difference between the web speed and the anvil speed is zero or approximately zero. Such synchronization of the web speed 96 and the anvil speed 98 at equal speeds enables the formation of "complete" bonding portions of the web 64 having a desired bonding strength.

[0056] In one particular embodiment of synchronizing the web speed / velocity 96 and the anvil speed / velocity 98 via the control system 82, as shown in FIG. 16, both the web speed 96 and the anvil speed 98 may be decelerated to zero during the bonding time 100 when forming the bonding portions on the web 64 (i.e., "zero speed bonding"). As used herein, the term zero speed bonding means that during the bonding of the web 64, the web speed 96 and the anvil speed 98 are decelerated to zero (i.e., not moving), or during the bonding of the web 64, the web speed 96 and the anvil speed 9 are decelerated to approximately zero, for example, a speed of 0 - 200 m / min. The implementation of zero speed bonding in the bonding system 62 beneficially forms a straight bonding line on the web 64 and is considered desirable from both a strength and an aesthetic point of view.

[0057] Referring to FIG. 13, according to one embodiment, a bonding system is operably coupled to a control system 82 and further includes a vision system, i.e., system 104, for providing feedback regarding a bonding portion formed on web 64. The vision system 104 may include a high-speed camera or other image capture device configured to acquire an image of the bonding portion formed by bonding apparatuses 70A, 70B. To acquire such a bonding image, the vision system 104 may be provided in each bonding apparatus 22. The vision system 104 provides the acquired image to a processor 86 of the control system 82 that analyzes the image to determine the bonding length in the processing direction. The determined length of the bonding portion may be used for many different control purposes. For example, determining that the bonding portion formed by bonding apparatuses 70A, 70B is of a desired length and / or is adjusted to a new bonding length from an existing bonding length, and identifying when the bonding length has been reached, etc.

[0058] According to one embodiment, the control system 82 operates as a closed-loop system that uses the acquired image as an input to selectively control the operation of servo motors 80A, 80B for the purpose of adjusting the rotational speed / velocity of anvils 76A, 76B and thereby controlling the bonding length. The closed-loop control technique implemented by the control system 82 enables on-the-fly adjustment of the bonding system 62, such as correcting specifically identified errors during operation, i.e., in bonding, and / or adjusting the bonding length to a desired value in response to a change in material or a change in product size. Such adjustment can be made without changing the machinery of the bonding system 62 and can instead be achieved by controlling the rotational speed / velocity of the anvils to artificially change the bonding length on web 64.

[0059] Referring to FIG. 17, there is provided a flow diagram showing a closed-loop control technique 110 implemented by a control system 82 for controlling the operation / speed of web 64 and anvils 76A, 76B, according to an embodiment of the present invention. Although technique 110 is described hereinafter in connection with the control of a bonding system using a plurality of bonding devices 70A, 70B (i.e., horn / anvil combinations), it is recognized that this technique may also be used to control a system using a single bonding device. As shown in FIG. 17, technique 110 starts at step 112 where an input is provided to control system 82 regarding a predetermined bonding length (in the processing direction) formed in web 64 for bonding layers 64A, 64B of the web together. The input may be provided to control system 82, for example, via an operator input, and may also be based on the size of the absorbent article to be produced and / or the material composition and thickness of the web material. As shown in step 114, upon input of the predetermined bonding length, control system 82 generates a command to move web 64 and anvils 76A, 76B according to initial speed characteristics, and operates to transmit the command signal to speed changer 68 and bonding devices 70A, 70B (i.e., servo motors 80A, 80B). As described above, web speed 96 and anvil (rotational) speed 98 may be controlled to have sinusoidal characteristics, where the speeds of web 64 and anvils 76A, 76B are synchronized with each other and have varying speeds during bonding time and non-bonding time. In one embodiment, web speed 96 and anvil speed 98 are in phase with each other, but are not the same during bonding time when a bonding portion is formed on web 64. On the other hand, in another embodiment, web speed 96 and anvil speed 98 are synchronized (i.e., equal) with each other during bonding time.

[0060] Under the initial settings executed by the control system 82, when the bonding system 62 starts operating, at step 116, the technique is that the vision system 104 acquires an image of the bonding portion formed by the bonding devices 70A, 70B, and then provides the image as input / feedback to the control system 82 and continues. The processor 86 of the control system 82 determines the bonding length in the processing direction and analyzes the image at step 118 to determine whether the bonding length matches the length set by the operator. As shown at 120, if it is determined that the bonding length does not match the length set by the operator, then at step 122, the technique is that the control system 82 sends a modified control signal to the servo motors 80A, 80B that drive the anvils 76A, 76B to change the motion / rotation speed and continues. The modified control signal causes an adjustment of the motion / rotation speed of the anvils 76A, 76B during at least the bonding time of the web 64 so that the speed mismatch between the web 64 and the anvils 76A, 76B is also corrected. The correction of the speed mismatch causes a corresponding change in the bonding length formed on the web 64. When step 122 is completed, then the technique 110 is that the vision system 104 acquires an image of the bonding portion, sends the image of the bonding portion to the control system 82 as input / feedback, and the control system 82 loops back to steps 116 and 118 to determine whether the bonding length matches the length set by the operator.

[0061] As shown at 124, if it is determined in step 118 that the bonding length matches the bonding length set by the operator, then the technique continues in step 126 with the control system 82 monitoring / determining whether a correction to the initial input has been received. The corrected input may be, for example, in the form of an input provided to the control system 82 via an operator input, and may be based on a change in the size / type of the product being processed by the bonding system 62, a change in the web material, and / or a change in the desired length / strength of the bonding portion formed on the web 64. The corrected input is considered to necessarily involve a change in the bonding length formed by the bonding apparatus.

[0062] As shown at 128, if it is determined in step 126 that a corrected input has been provided to the control system 82, then the technique continues in step 130 with the control system 82 sending modified control signals to the servo motors 80A, 80B that drive the anvils 76A, 76B (and optionally the speed changer 68) to change the motion / rotation speed in accordance with the corrected input. The modified control signals cause an adjustment of the motion / rotation speed of the anvils 76A, 76B (and the web 64) for at least the bonding time of the web 64 so that the speed mismatch between the web 64 and the anvils 76A, 76B is also corrected. The correction of the speed mismatch causes a corresponding change in the bonding length formed on the web 64. When step 130 is complete, the technique then loops back to steps 116 and 118 where the vision system 104 acquires an image of the bonding portion, transmits the image of the bonding portion to the control system 82 as input / feedback, and the control system 82 determines whether the bonding length matches the length set by the operator.

[0063] As shown by 132, if it is determined in step 126 that the corrected input has not been provided to the control system 82, then the technique is that the vision system 104 acquires an image of the bonding part, transmits the image of the bonding part to the control system 82 as input / feedback, and then the control system 82 loops back to steps 116 and 118 to determine whether the bonding length matches the length set by the operator. That is, the control system 82 monitors the operation of the bonding system to confirm that the bonding part formed on the web 64 continues to match the desired bonding part in the initial input settings provided to the control system 82.

[0064] Referring to FIG. 18, another embodiment of a bonding system 136 is illustrated that includes one or more cammed, i.e., "wobble," anvils that follow a predefined cyclical speed characteristic. Instead of the rotary anvils 76A, 76B depicted in FIG. 13, cammed anvils 138A, 138B may be used in the bonding system 136, which advantageously provide a faster cycle time and / or enable low speed operation (i.e., low web speed and anvil motion / speed) of the bonding system 136. Each cammed anvil 138A, 138B includes a cam wheel 140 having a cam track or cam surface 142 formed therein, a cam member 144 that moves within / around the cam track 142 as the cam wheel rotates, and an anvil body 146 attached to the cam member 144 so as to move with the cam member 144, the anvil body 146 showing a surface that interacts with horns 78A, 78B to enable the formation of ultrasonic bonding portions on the web 64. The cam track 142 may include an irregular, i.e., elliptical, track on which the cam member 144 rides. Since the cam member 144 rides along the cam track 142, the anvil bodies 146 are caused to operate together, and the operation of the anvil bodies 146 in this case includes both vertical (up and down) and horizontal motion. When forming a bonding portion on the web 64 moving at the web speed in the processing direction, some horizontal motion in the processing direction 66 of the anvil body 64 is required, and thus the horizontal motion occurs in the processing direction when the anvil body 146 is close to the horns 78A, 78B and a bonding portion is formed on the web 64 through the interaction between the anvil body and the horns. In another embodiment, when zero speed bonding is implemented, it is recognized that in such an embodiment, the horizontal motion / rotation of the anvil body 146 is not required, and thus the anvil body 146 may exhibit only vertical motion.

[0065] In the process of the bonding system 136, servo motors 80A, 80B operably connected to the cam anvils 138A, 138B rotate the wheel 140, whereby the cam member 144 rides on the cam track 142, generating a periodic movement of the anvil body 146 relative to the horns 78A, 78B at a desired period and speed. In the process of the bonding apparatuses 70A, 70B, the control system 82 controls the operation of the servo motors 80A, 80B to synchronize the movement / rotation speed of the cam anvils 138A, 138B with the movement / rotation speed of the web 64. The speed characteristics of the web 64 and the anvils 138A, 138B may be controlled by the control system 82 to match any characteristics shown, for example, in FIGS. 14 - 16, and thus may be controlled as synchronized movement / speed, as synchronous movement / speed, or according to speed zero bonding control.

[0066] Thus, embodiments of the present invention advantageously provide an apparatus and method for controlling the speeds of both a continuous web and a bonding apparatus to achieve a stronger bonding portion on the web while including synchronizing and / or matching speeds at a desired bonding time. The anvils in each of the one or more anvil / horn combinations are selectively driven by servo motors such that their movement / speed is synchronized with the movement / speed of the web being bonded. By synchronizing the speed / speed of the web with the speed / speed of the anvil in the bonding system, the dwell time of the anvil relative to the web can be selectively controlled, and for example, the dwell time can be maximized as needed. By controlling the dwell time of the anvil relative to the web, it becomes possible to form a bonding portion of a desired length (in the processing direction) on the web, and the bonding length can be selectively controlled based on the product type / size, web material, and the strength of the required bonding portion.

[0067] Also, embodiments of the present invention advantageously provide a system for selectively controlling the distance between a selected anvil and horn and adjacent anvils and horns. A vision system can acquire data regarding the distance between adjacent anvil-horn combinations, and this data is used in a closed-loop control system. In this closed-loop control system, the control system causes a motor and associated linear actuator to selectively adjust the position of one or more anvil-horn combinations, or enables an operator to actively control the motor and associated linear actuator, based on data provided to the operator, to selectively adjust the position of one or more anvil-horn combinations.

[0068] Accordingly, according to one embodiment of the present invention, a system for bonding a web comprising at least a pair of web layers includes a speed-changing device for increasing or decreasing the speed of the web in the (machine) processing direction, an anvil and a corresponding ultrasonic horn that interact to form an ultrasonic bonding portion on the web, and an anvil actuator configured to control the operation of the anvil. The control system also includes a bonding system that controls the operation of the anvil actuator and the speed-changing device, and the control system is programmed to control the operation of the anvil such that when the web passes between the anvil and the ultrasonic horn, the moving speed of the web is decreased from the feed speed to the bonding speed and the operation of the anvil is synchronized with the moving speed of the web.

[0069] In another embodiment of the present invention, a method of bonding a web having at least a pair of web layers includes moving the web in a processing direction via a feed assembly, the feed assembly being configured to selectively control the speed of the web. The method also includes conveying the web to one or more bonding devices, each of the one or more bonding devices comprising an anvil, a ultrasonic horn that interacts with the anvil to form an ultrasonic bonding portion on the web, and an anvil actuator configured to control the speed of the anvil. The method further includes controlling the operation of the anvil actuator and the feed assembly to synchronize the speed of the web with the speed of the anvil by dropping the speed of the web and the speed of the anvil to a web bonding speed and an anvil bonding speed when the web passes between the anvil and the ultrasonic horn.

[0070] The present invention has been described in detail only with respect to a limited number of embodiments, but it will be readily understood that the present invention is not limited to such disclosed embodiments. Rather, the present invention can be modified by incorporating a number of changes, variations, substitutions, or equivalent configurations that are not described herein but are equivalent to the claims of the present invention. Further, although various embodiments of the present invention have been described, it should also be understood that aspects of the present invention may include only a portion of the described embodiments. Thus, the present invention is not considered to be limited by the foregoing description and is defined by the claims.

Claims

1. A bonding system (62, 136) for bonding a web (64) comprising at least a pair of web layers (64A, 64B), a speed changing device (68) for increasing or decreasing the speed of the web (64) in the processing direction, an anvil (76A, 76B, 138A, 138B) and a corresponding ultrasonic horn (78A, 78B) that interact to form an ultrasonic bonding portion on the web (64), an anvil actuator (80A, 80B) configured to control the movement of the anvil (76A, 76B, 138A, 138B), and a control system (82) for controlling the operation of the anvil actuator (80A, 80B) and the speed changing device (68), wherein the control system (82) when the web (64) passes between the anvil (76A, 76B, 138A, 138B) and the ultrasonic horn (78A, 78B), reduces the moving speed of the web (64) from the feed speed (V1) to the bonding speed (V2), controls the operation of the anvil (76A, 76B, 138A, 138B) so that a change in the moving speed of the anvil (76A, 76B, 138A, 138B) is synchronized with a change in the moving speed of the web (64), is programmed to be like this, the interaction between the anvil (76A, 76B, 138A, 138B) and the ultrasonic horn (78A, 78B) forms the ultrasonic bonding portion having the bonding length in the processing direction, and the control system (82) selectively controls the residence time of the anvil (76A, 76B, 138A, 138B) on the web (64), thereby controlling the bonding length of the ultrasonic bonding portion in the processing direction. A bonding system (62, 136) characterized in that it is programmed to control the magnitude of the speed mismatch between the moving speed of the anvil (76A, 76B, 138A, 138B) and the bonding speed (V2) of the web (64).

2. The anvil (76A, 76B, 138A, 138B) includes a rotary anvil (76A, 76B), and the control system (82) operates the anvil actuator (80A, 80B) to control the rotation speed of the rotary anvil (76A, 76B). The bonding system (62, 136) according to claim 1, characterized in that.

3. The control system (82) is configured such that when the web (64) moves at the bonding speed (V2) while passing between the anvil (76A, 76B, 138A, 138B) and the ultrasonic horn (78A, 78B), the change in the rotation speed of the rotary anvil (76A, 76B) is synchronized with the change in the moving speed of the web (64). The bonding system (62, 136) according to claim 2, characterized in that the anvil actuator (80A, 80B) is programmed to operate.

4. The control system (82) is programmed to control the anvil actuator (80A, 80B) such that the change in the rotation speed of the rotary anvil (76A, 76B) is synchronized with the change in the moving speed of the web (64), and the rotation speed of the rotary anvil (76A, 76B) and the bonding speed (V2) of the web (64) The bonding system (62, 136) according to claim 2, characterized in that there is a speed mismatch between them.

5. The control system (82) is programmed to operate each of the speed changing device (68) and the anvil actuator (80A, 80B) such that the bonding speed (V2) of the web (64) and the rotation speed of the rotary anvil (76A, 76B) are 0 - 200 m / min to provide bonding with zero speed of the web (64). The bonding system (62, 136) according to claim 2, characterized in that.

6. The anvil (76A, 76B, 138A, 138B) includes a swing anvil (138A, 138B), and the control system (82) controls the rotation speed of the swing anvil (138A, 138B) to control its operations in the vertical direction and the processing direction. The bonding system (62, 136) according to claim 1, characterized in that.

7. The control system (82) is programmed to operate the anvil actuators (80A, 80B) such that when the web (64) moves at the bonding speed (V2) while passing between the anvil and the ultrasonic horns (78A, 78B), a change in the speed of the operation of the rocking anvils (138A, 138B) in the processing direction is synchronized with a change in the moving speed of the web (64). The bonding system (62, 136) according to claim 6, characterized in that.

8. The control system (82) is programmed to operate the anvil actuators (80A, 80B) such that a change in the moving speed of the rocking anvils (138A, 138B) in the processing direction is synchronized with a change in the moving speed of the web (64), and there is a speed mismatch between the moving speed in the processing direction and the bonding speed (V2) of the web (64). The bonding system (62, 136) according to claim 6, characterized in that.

9. The control system (82) is programmed to operate each of the speed changing device (68) and the anvil actuators (80A, 80B) such that the bonding speed (V2) of the web (64) and the rotational speed of the rocking anvils (138A, 138B) are 0 - 200 m / min to provide zero bonding of the web (64). The bonding system (62, 136) according to claim 6, characterized in that.

10. The bonding system (62, 136) according to claim 1, further comprising a vision system (104) operably communicated with the control system (82) to monitor the bonding length of the ultrasonic bonding portion and configured to acquire an image of the ultrasonic bonding portion.

11. The control system (82) receives the image from the vision system (104), identifies the bonding length of the ultrasonic bonding portion based on the image, compares the identified bonding length with a predetermined bonding length desired, If the specified bonding length does not match the desired specific bonding length, the anvil actuators (80A, 80B) are programmed to control the operation of the anvils (76A, 76B, 138A, 138B) so that the bonding length matches the desired predetermined bonding length. The bonding system (62, 136) according to claim 10, characterized in that.

12. The anvils (76A, 76B, 138A, 138B) include a first anvil (76A, 138A), the ultrasonic horns (78A, 78B) include a first ultrasonic horn (78A), and the anvil actuators (80A, 80B) include a first anvil actuator (80A). The bonding system (62, 136) further includes a second anvil (76B, 138B) and a corresponding second ultrasonic horn (78B) that interact to form the ultrasonic bonding portion on the web (64). The second anvil (76B, 138B) and the second ultrasonic horn (78B) are spaced apart from the first anvil (76A, 138A) and the first ultrasonic horn (78A) in the processing direction. The second anvil (76B, 138B) has a second anvil actuator (80A) operably coupled to control the movement of the second anvil (76B, 138B). The control system (82) controls the operation of the second anvil actuator (80B) so that the moving speed of the second anvil (76B, 138B) matches the moving speed of the first anvil (76A, 138A). The bonding system (62, 136) according to claim 1, characterized in that.

13. The bonding system further includes a third anvil (14C) and a corresponding third ultrasonic horn (16C) that interact to form the ultrasonic bonding portion on the web (64). The third anvil (14C) and the third ultrasonic horn are spaced apart from the first anvil and the first ultrasonic horn in the processing direction by a gap. The third anvil (14C) has a third anvil actuator operably coupled to control the operation of the third anvil (14C). The bonding system (62, 136) according to claim 12, wherein the control system (82) controls the operation of the third anvil actuator such that the moving speed of the third anvil (14C) matches the moving speeds of the first anvil (76A, 138A) and the second anvil (76B, 138B).

14. A method of bonding a web (64) having at least a pair of web layers (64A, 64B), comprising: Moving the web (64) in a processing direction via a feed assembly (68), the feed assembly (68) being configured to selectively control the speed of the web (64); Conveying the web (64) to one or more bonding devices (70A, 70B), each of the one or more bonding devices (70A, 70B) including an anvil (76A, 76B, 138A, 138B), A ultrasonic horn (78A, 78B) that interacts with the anvil (76A, 76B, 138A, 138B) to form an ultrasonic bonding portion on the web (64), An anvil actuator (80A, 80B) configured to control the speed of the anvil (76A, 76B, 138A, 138B); Controlling the operations of the anvil actuator (80A, 80B) and the feed assembly (68) such that when the web (64) passes between the anvil (76A, 76B, 138A, 138B) and the ultrasonic horn (78A, 78B), the speed of the web (64) and the speed of the anvil (76A, 76B, 138A, 138B) are reduced to a web bonding speed (VW2) and an anvil bonding speed (VA2), thereby synchronizing the change in the speed of the web (64) with the change in the speed of the anvil (76A, 76B, 138A, 138B); Selectively controlling the residence time of the web (64) on the anvil (76A, 76B, 138A, 138B), thereby selectively controlling the magnitude of the speed mismatch between the web bonding speed (VW2) and the anvil bonding speed (VA2) so as to control the bonding length of the ultrasonic bonding portion in the processing direction.

15. obtaining an image of the ultrasonic bonding portion via the vision system (104); determining a bonding length of the ultrasonic bonding portion based on the obtained image; comparing the determined bonding length with a predetermined bonding length desired; controlling the anvil actuator (80A, 80B) to adjust the speed of the anvil (76A, 76B, 138A, 138B) such that the determined bonding length matches the predetermined bonding length desired if the determined bonding length does not match the predetermined bonding length desired. The method according to claim 14, characterized by comprising:

16. The method according to claim 14, further comprising synchronizing a change in the web bonding speed (VW2) and a change in the anvil bonding speed (VA2) such that the speed difference becomes zero.

17. The method according to claim 16, further comprising performing bonding with a zero speed of the web (64) by controlling the web bonding speed (VW2) and the anvil bonding speed (VA2) to be 0 - 200 m / min.

18. The anvil (76A, 76B, 138A, 138B) comprises a rotary anvil (76A, 76B, 138A, 138B), and the method comprises controlling the rotational speed of the rotary anvil (76A, 76B) via the anvil actuator (80A, 80B) such that a change in the speed of the web (64) synchronizes with a change in the rotational speed of the rotary anvil (76A, 76B). The method according to claim 14, characterized by comprising:

19. The anvil (76A, 76B, 138A, 138B) comprises a rocking anvil (138A, 138B), and the method comprises controlling the speed of the rocking anvil (138A, 138B) via the anvil actuator (80A, 80B) to synchronize a change in the speed of the web (64) with a change in the speed of the rocking anvil (138A, 138B), and controlling operations of the rocking anvil in the vertical direction and the processing direction. The method according to claim 14, characterized by comprising:

Images