Multiple path bonding

High speed, continuous processing of product pieces with desirably extended durations of application of bonding or bonding energy.

FIELD OF THE INVENTION
 This invention relates generally to processing involving the bonding
 together of two or more items or sections of a single item and, more
 particularly, to bond processing using multiple paths.
 BACKGROUND OF THE INVENTION
 Disposable absorbent pant-like garments for use as a child's training
 pants, adult incontinence garment and the like have grown in popularity
 and use. For example, Van Gompel et al., U.S. Pat. No. 4,940,464, issued
 Jul. 10, 1990, the disclosure of which is incorporated herein by reference
 in its entirety, discloses such garments and the manufacture thereof.
 FIG. 1 is a perspective view of one embodiment of such a garment or pant,
 generally designated by the reference numeral 10, as it would appear on a
 wearer indicated in dash lines. The garment 10 generally comprises a waste
 containment section 12 and two side panels 14 and 16, respectively,
 defining a waist opening 20 and a pair of leg openings 22 and 24,
 respectively. More particularly, the side panel 14 is composed of a pair
 of stretchable side members 26 and 30 bonded together along or to form a
 seam 32. Similarly, the side panel 16 is composed of a pair of stretchable
 side members 36 and 40 bonded together along or to form a seam 42.
 Various bonding techniques are available to effect bonding of such members
 or other member materials to form such side seams or the like. For
 example, one bonding technique which has found growing application
 involves the application of ultrasonic energy. For example, Neuwirth et
 al., U.S. Pat. 5,096,532, issued Mar. 17, 1992 and Ehlert, U.S. Pat. No.
 5,110,403, issued May 5, 1992, the disclosures of each of which is
 incorporated herein by reference in its entirety, generally relate to
 ultrasonic rotary horns useful in such processing.
 While various techniques are available for the bonding together of side
 members or the like, typically such bonding techniques involve or require
 prolonged bonding or dwell times in order to better ensure the formation
 and maintenance of proper and effective bonding of the side members. For
 example, bond strength is generally a function of dwell time, with
 correspondingly increased dwell times generally resulting in improved or
 stronger bond formation. As will be appreciated, such prolonged bond
 processing times can dramatically limit the rate at which such garments
 can be processed through a conventional process machinery line.
 Thus, there is a need and a demand for processing improvements effective to
 avoid or minimize the rate limiting effects of bonding on the
 manufacturing line processing of such associated products.
 SUMMARY OF THE INVENTION
 A general object of the invention is to provide an improved process for the
 bonding of a series of pieces each to itself.
 A more specific objective of the invention is to overcome one or more of
 the problems described above.
 The general object of the invention can be attained, at least in part,
 through a high speed process for bonding a series of pieces each to
 itself. In accordance with one embodiment of the invention, such a process
 involves splitting a supplied series of pieces to be bonded into first and
 second subseries of pieces to be bonded. The first subseries of pieces to
 be bonded are subsequently bonded to form a first series of bonded pieces.
 Similarly, the second subseries of pieces to be bonded are bonded to form
 a second series of bonded pieces.
 The prior art generally fails to provide methods or processing techniques
 which provide desirably prolonged or extended dwell times, such as may be
 desired for at least certain types of bonding, in the context of high
 speed manufacture or processing. More particularly, the prior art
 generally fails to provide such desirably prolonged or extended dwell
 times relative to such bond formation via the application of ultrasonic or
 thermal energy or the like.
 The invention further comprehends a continuous high speed process for
 ultrasonic bonding a series of pieces each to itself. In accordance with
 one embodiment of the invention, such a process involves alternatingly
 splitting a series of pieces to be bonded into first and second subseries
 of pieces to be bonded. Members of the first subseries of pieces to be
 bonded are folded into bonding relative position. Members of the second
 subseries of pieces to be bonded are folded into bonding relative
 position. The folded first subseries of pieces to be bonded are
 ultrasonically bonded to form a first series of bonded pieces. The folded
 second subseries of pieces to be bonded are ultrasonically bonded to form
 a second series of bonded pieces.
 In accordance with another preferred embodiment of the invention, there is
 provided a process for side seam bonding of a disposable pant-like garment
 for absorbing human discharge. The process involves supplying a series of
 planar garment precursor pieces to be bonded. The series of pieces to be
 bonded is alternatingly split into first and second subseries of pieces to
 be bonded. The members of the first and second subseries of pieces to be
 bonded are folded into bonding relative position. The folded members of
 the first subseries of pieces to be bonded are sequentially ultrasonically
 bonded to form a first series of bonded pieces and the folded members of
 the second subseries of pieces to be bonded are sequentially
 ultrasonically bonded to form a second series of bonded pieces in a manner
 wherein a folded member of the first subseries of pieces to be bonded and
 a folded member of the second subseries of pieces to be bonded are bonded
 substantially simultaneously.
 Other objects and advantages will be apparent to those skilled in the art
 from the following detailed description taken in conjunction with the
 appended claims and drawings.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
 The present invention, as is described in more detail below, provides an
 improved process for bonding a series of pieces each to itself.
 While the invention is described below with particular reference to side
 seam bonding, such as by application of ultrasonic energy, of a disposable
 pant-like garment for absorbing human discharge, it is to be understood
 that the invention also has applicability to not only other bonding
 techniques such as thermal bonding, for example, but also can, if desired,
 be used to process other types or kinds of pieces being bonded.
 Referring to the drawings and initially referring particularly to FIG. 2,
 there is illustrated a simplified schematic of a processing assembly,
 generally designated by the reference numeral 100, in accordance with one
 embodiment of the invention. To facilitate discussion and description, the
 opposed sides of the processing assembly 100 are herein generally referred
 to as the drive side and the operator side, as signified by the arrows 102
 and 104, respectively.
 As shown, a continuous web 106 is introduced to the processing assembly 100
 such as via a conveyor belt and has a direction of travel signified by the
 arrow 111. In accordance with one preferred embodiment of the invention,
 the continuous web 106, also commonly referred to as a "sausage," is
 generally composed of various layers of materials such as desired and
 included in the particular product being processed. For example, for a
 disposable pant-like garment for absorbing human discharge herein
 described, such a continuous web or sausage 106 is generally an assembly
 composed of one or more layers of material. While such disposable
 pant-like garment for absorbing human discharge can be variously
 constructed, in practice the pant-like garment will include one or more
 liquid-pervious liners, absorbent inserts, and a liquid impervious outer
 cover such as composed of a cloth-like material. The continuous web 106
 additionally may generally include flaps, waist band elastic, leg
 elastics, etc. or the like such as may serve to facilitate the placement
 and attachment of the final product onto an appropriate individual. In
 practice, the continuous web will have a repeat length which will be
 dependent on the grade or size of the specific garment product being
 manufactured. For example, a children's training pant garment will
 typically be formed using a continuous web having a repeat length of about
 16 to about 32 inches with the specific repeat length again being
 dependent on the grade or size of the training paint garment being formed.
 It will be understood, however, that the broader practice of the invention
 is not limited by the specific construction, shape, form or size of the
 web or the product being processed. For example, if desired, the invention
 can be practiced in conjunction with a web composed of a single material.
 In the processing assembly 100, the continuous web 106 is transferred to a
 vacuum incline conveyor 112. With such a conveyor, a vacuum is created or
 generated, such as is known in the art and such as may serve to hold the
 web 106 to the underside thereof and to pull the web at full web speed.
 For example, such a vacuum can be created by a fan (not shown) pulling air
 (signified by the arrow 113) out through the duct 114 on the operator side
 104. Alternatively or in addition, such a vacuum could be created by
 drawing air from the drive side 102, if desired.
 The vacuum of the conveyor 112 is turned off or released at or about the
 tangent point 116. The web 106 is there transferred onto a vacuum folding
 drum 120 whereat a vacuum is created or generated, such as is known in the
 art and such as may serve to hold the web 106 thereto. The vacuum folding
 drum 120 has a direction of rotation signified by the arrow 121. In the
 illustrated embodiment, the folding drum 120 includes four (4) plates or
 stations 122 (a-d). For example, each such plate or station 122(a-d) may
 be of a vacuum form timed to form or "pull" a vacuum at the transfer
 tangent point 116 with the vacuum incline conveyor 112 and such as to
 effect the transfer of the web 106 thereon. It is to be understood,
 however, that the broader practice of the invention is not limited by the
 number of plates or stations of the folding drum and folding drums. For
 example, folding drums with greater or fewer number of plates or stations
 can, if desired, be used.
 In the processing assembly 100, the web 106 on the plate 122a is acted upon
 by a knife roll 124 which has a direction of rotation signified by the
 125. The knife roll 124 includes first and second cuffing edges 126 and
 130, respectively. More specifically, the knife roll cutting edge 126
 contacts a blade cutting surface 132a on the plate 122a or otherwise
 serves to cut the web 106 into discrete, generally planar pieces prior to
 the folding of such pieces. As shown, each of the plates 122(a-d) may
 incorporate or include a corresponding blade cutting surface 132(a-d). As
 will be appreciated, the broader practice of the invention is not limited
 by the number of cutting edges as for example, knife rolls with one or
 more cutting edges can be used. Further, suitable cutting devices other
 than knife rolls and such as known in the art can, if desired, be used.
 The processing assembly 100 then forms or consists of a first or upper
 process line 140 and a second or lower process line 142 such as to
 respectively process first and second subseries of pieces to be bonded.
 The process lines 140 and 142 are generally similar to each other and are
 designed to facilitate the high speed processing of product pieces while
 providing relatively extended bond dwell times for the product pieces
 being processed therethrough.
 The processing assembly 100 includes first and second station pairs of
 folding blade assemblies 150 and 152, respectively, whereby members of the
 first and second subseries of pieces to be bonded are folded into bonding
 relative position. The construction and operation of such folding blades
 are well known in the art and do not form limitations on the broader
 practice of the present invention. In general, each of the pairs of
 folding blades 150 and 152, respectively, are timed and synchronized to
 make one revolution every two product pieces such that in a series of
 product pieces, every other product piece is folded by the first station
 pair of folding blades 150 while each of the alternating product pieces is
 folded by the second pair of folding blades 152. As a result of such
 processing, a series of pieces to be bonded is alternatingly divided into
 first and second subseries of pieces to be bonded.
 Associated with the first and second station pairs of folding blades 150
 and 152 are first and second variable speed conveyor assemblies 160 and
 162, respectively, such as in the form of smooth belt conveyors that can
 act to nip and convey the folded product pieces for subsequent processing
 in accordance with the invention. Associated with each of the first and
 second conveyor assemblies 160 and 162 is a pair of bonders 170 and 171,
 respectively, for the process line 140 and bonders 172 and 173,
 respectively, for the process line 142. The bonders are effective to form
 a bond, specifically a side seam bond such as the side seam bonds 32 and
 42, respectively, shown in the garment 10 in FIG. 1, with each of such
 pairs of bonders forming a side seam bond on the opposed sides of a folded
 product piece processed therethrough. In a preferred embodiment of the
 invention such oppositely disposed side seams are formed substantially
 simultaneously.
 Various bonding techniques are available to effect bonding of such members
 or other member materials such as to form such side seams or the like. For
 example, as identified above, such bonding techniques may involve the
 application of ultrasonic energy. Alternatively, such bonding may take the
 form of thermal bonding such as involving the application of thermal
 energy to the piece or pieces being bonded. As will be appreciated by
 those skilled in the art, other bonding techniques such as known in the
 art may, if desired, be used.
 In accordance with the invention, the conveyors 160 and 162 do not run at a
 constant speed. Rather, the conveyors 160 and 162 run at an operating
 speed which is about 10% faster than the tip velocities of the associated
 folding blades 150 and 152, respectively, during the time period the
 folding blades are interacting with the conveyors. The conveyors 160 and
 162 then run at a reduced speed in conveying product pieces through the
 seam bonder pairs 170 and 171, respectively, and 172 and 173,
 respectively. As will be appreciated, such reduced conveyance speed
 through the bonders is often helpful in providing an extended bond dwell
 time such as may be desired or required to effect bonding of desired
 strength.
 Various means and techniques, such as known in the art, are available
 whereby the conveyance speed of the conveyors 160 and 162 can be variably
 controlled. For example, such take away conveyors can desirably be
 controlled such as by elliptical gearing or servo motors such that the
 conveyors travel at full web speed during folding but slow down to a speed
 of about one-fourth of full web speed as the respective pieces to be
 bonded are passed through the corresponding bonder.
 In practice, it will be appreciated that through such processing
 arrangement, each of the process lines 140 and 142, respectively, need
 process (e.g., bond) a respective subseries of pieces to be bonded at a
 speed of no more than about one-half and, desirably, at about one-fourth
 the speed at which pieces to be bonded are discharged or produced with the
 folding drum 120. As will be appreciated, such bond processing speeds can
 be further correspondingly reduced such as through the inclusion of
 additional similar such processing lines.
 While the use of variable speed conveyor assemblies such as the
 above-described conveyor assemblies 160 and 162 are one preferred
 arrangement for providing the desired extended processing times through
 associated bonders, it will be understood that the broader practice of the
 invention is not necessarily so limited. For example, if desired, the
 invention can alternatively be practiced with a process line composed of a
 combination of a first constant speed conveyor to initially accept folded
 product pieces from the respective station folding blades, followed by a
 processing conveyor to process the folded product pieces through an
 associated bonder. In practice, such first constant speed conveyors will
 preferably run or operate at a conveyance speed of about 0 to 10% faster
 than the speed at which pieces to be bonded are discharged or produced
 with the associated folding drum such as to avoid undesired processing
 backups. The following processing conveyors can, in turn, desirably
 operate at a conveyance speed of no more than about one-half and,
 desirably, at about one-fourth the speed at which pieces to be bonded are
 discharged or produced with the associated folding drum in order to
 provide desired extended processing times through an associated bonder.
 Each of the process lines 140 and 142 may additionally include post-bonding
 processing apparatuses such as shear slitters 180 and 182 such as may be
 desired to assist in the removal of excess material from the bonded
 product pieces.
 The bonded pieces can then be subjected to various particular processing
 operations, such as known in the art. For example, such bonded pieces can
 be subsequently processed such as through tucking, stacking and packaging
 sections, such as known in the art.
 In accordance with certain preferred embodiments of the invention and as
 shown in FIG. 3, the resulting bonded product pieces of the first and
 second processing lines 140 and 142, respectively, such as supplied by the
 conveyors 160 and 162, respectively, can be further processed separately
 such as via the conveyors 184 and 186, respectively.
 Alternatively, in accordance with one preferred embodiment of the invention
 and as shown in FIG. 4, the resulting bonded product pieces of the first
 processing line 140 such as supplied by the conveyors 160 (such product
 pieces here designated with the reference numeral 188) and the resulting
 bonded product pieces of the second processing line 142 such as supplied
 by the conveyors 162 (such product pieces here designated with the
 reference numeral 189) can be recombined such as by means of recombining
 conveyors 190 and 192 to form a single product stream 194. The product
 stream 194 can then be conveyed by a product conveyor 196. Such combining
 of the resulting product pieces of the separate processing lines 140 and
 142 for subsequent processing (e.g., tucking, stacking, packaging, etc.)
 can dramatically reduce equipment costs and operating efficiencies by
 processing the bonded product pieces through the same processing
 equipment.
 In view of the above, it will be appreciated that methods or processing
 techniques of the present invention generally provide or result in
 desirably prolonged or extended dwell times, such as may be desired for at
 least certain types of bonding, in the context of high speed manufacture
 or processing. More particularly, the invention generally provides such
 desirably prolonged or extended dwell times relative to such bond
 formation via the application of ultrasonic or thermal energy or the like.
 The invention illustratively disclosed herein suitably may be practiced in
 the absence of any element, part, step, component, or ingredient which is
 not specifically disclosed herein.
 While in the foregoing detailed description this invention has been
 described in relation to certain preferred embodiments thereof, and many
 details have been set forth for purposes of illustration, it will be
 apparent to those skilled in the art that the invention is susceptible to
 additional embodiments and that certain of the details described herein
 can be varied considerably without departing from the basic principles of
 the invention.