US20010010249A1 - Machine and process for placing and bonding elastic members in a relaxed state to a moving substrate web - Google Patents

Abstract

A machine and process are disclosed for bonding an elastic member to a moving substrate web while the elastic member is in an un-stretched condition. The machine provides for upwardly folding a moving substrate web along a longitudinal centerline while maintaining the side edge regions of the web in a flat un-folded or un-gather condition. An elastic member is applied to the moving web while the elastic member is un-stretched, applying the first and second end regions of the elastic member to the respective first and second side edge regions of the moving web. The end regions of the elastic member are next bonded to the side edges of the web, leaving the remainder of the elastic member un-bonded to the web. The web is then un-folded or un-gathered to its first normal width, stretching the bonded elastic member. At least a portion of the remainder of the elastic member previously un-bonded to the web is then bonded to the web, and the stretched elastic member is allowed to relax.

Description

TECHNICAL FIELD
• This invention relates to machines and to industrial processes. More particularly, the invention concerns a machine and a process for placing and bonding an elastic member to a moving substrate web while the elastic member is in an un-stretched or relaxed state.[0001]
BACKGROUND OF THE INVENTION
• In the manufacture of infant diapers, adult incontinence garments and the like, it is frequently desirable to attach an elastic member to the remainder of the diaper or garment in order to secure the diaper or garment about the legs or waist of the user. Typically, these articles are manufactured by a high-speed process in which individual parts of the diaper or garment are affixed to a moving web of material by adhesive or ultrasonic bonding. U.S. Pat. Nos. 3,987,794: 3,990,450: 3,995,638; 3,995,640; and 4,014.338 to Schaar describe such infant diapers having an elasticized waist band.[0002]
• One problem associated with this process relates to the attachment of the elastic member to the moving web. In prior art machines and processes in which the elastic member is bonded to the substrate web in the stretched condition, there is frequently a tendency for the stretched elastic member to pull away from the substrate web before the bonds become fully annealed. Attempts to solve this problem center around various schemes for attaching the elastic member to the substrate web in an un-stretched condition.[0003]
• U.S. Pat. No. 4,240,866 and its divisional, United States[0004]Patent4,285,747 to Rega describe a process of manufacture whereby an elastic waist member is attached in an un-stretched state to a substrate web in the manufacture of infant diapers.
• U.S. Pat. No. 4,337,771 to Pieniak, et al. describes an infant diaper with an elongated elastic strip secure to at least one margin of the diaper at a central portion of the margin, with a unitary, relatively inelastic reinforced region in a corner of the diaper.[0005]
• U.S. Pat. No. 4,400,227 to Riemersma discloses a method of applying elasticized garment cuffs in a stretched condition to a substrate web.[0006]
SUMMARY OF THE INVENTION
• In accordance with the present invention the is provided, in its principal embodiment, a machine for placing and bonding elastic members in an un-stretched state to a substrate web. The elastic members have first and second ends defining a first un-stretched length, first and second end regions respectively proximate the first and second ends, and the substrate web has a longitudinal axis and first and second edges defining a first width, with first and second side regions respectively proximate the first and second edges.[0007]
• The machine comprises an apparatus for gathering the substrate web to a second width which is less than the first width, and holding the gathered substrate web at this second width while receiving the elastic member in an un-stretched state. The elastic member is received on the substrate web in such an orientation that its length is in a direction transverse to the longitudinal axis of the substrate web.[0008]
• An apparatus of the machine then bonds the first and second end regions of the elastic member to the first and second edge regions of the substrate web while the substrate web is gathered and the elastic member is in an un-stretched state. The bonding of the two ends of the relaxed elastic member to the substrate web leaves the remainder of the length of the elastic member un-bonded to the substrate web.[0009]
• The machine further provides an apparatus for stretching the bonded elastic member while simultaneously un-gathering the substrate web to its first width. An apparatus of the machine then bonds at least a portion of the remainder of the length of the elastic member to the substrate web while the elastic member is in the stretched state.[0010]
• In an alternative embodiment, the present invention provides a process for placing and bonding elastic members in an un-stretched state to a substrate web. The elastic members have first and second ends and a first un-stretched length, with first and second end regions respectively proximate the first and second ends. The substrate web has a longitudinal axis or centerline, first and second side edges defining a first width, and first and second side edge regions respectively proximate the first and second side edges.[0011]
• The process of the invention comprises the steps of first gathering the substrate web to a second width which is less than the first width, and holding the gathered substrate web at this second width. Next, an elastic member is placed in an un-stretched state on the substrate web with the length of the elastic member being transverse to the longitudinal axis of the substrate web.[0012]
• In the next step, the first and second end regions of the elastic member are bonded respectively to the first and second side edge regions of the substrate web while the elastic member is in an un-stretched state, leaving the remainder of the length of the elastic member un-bonded to the substrate web.[0013]
• Next, bonded elastic member is-stretched, simultaneously un-gathering the substrate web to its first width. Finally, at least a portion of the remaining previously un-bonded length of the elastic member is bonded to the substrate web while the elastic member is in the stretched state.[0014]
BRIEF DESCRIPTION OF THE DRAWINGS
• The operation of the machine and process of the invention can be more readily understood by reference to the drawing figures which form a part of the disclosure of the invention.[0015]
• In The Drawing:[0016]
• FIG. 1 is a schematic perspective representation of one embodiment of the machine of the present invention.[0017]
• FIG. 2 is a perspective view of a “shoe-horn” apparatus of the machine of the invention for folding or gathering the substrate web.[0018]
• FIG. 3 is an exploded perspective view of the shoe-horn apparatus of FIG. 2 showing its component parts.[0019]
• FIG. 4 is a top view of the header plate of the shoe-horn apparatus of FIG. 2.[0020]
• FIG. 5 is a side view of the header plate of the shoe-horn apparatus of FIG. 2.[0021]
• FIG. 6 is an end view of the header plate of the shoe-horn apparatus of FIG. 2.[0022]
• FIG. 7 is a perspective view of one embodiment of the combination roller of the machine of the present invention.[0023]
• FIG. 8 is a perspective view of the main body member of the combination roller of FIG. 7.[0024]
• FIG. 9 is a perspective view of an ultrasonic bonding anvil hold-down shoe for the combination roller of FIG. 7.[0025]
• FIG. 10 is a perspective view of an ultrasonic bonding anvil shoe for the combination roller of FIG. 7.[0026]
• FIG. 11 is a cross-sectional view of the ultrasonic bonding anvil hold-down shoe of FIG. 9 taken along cut line A-A.[0027]
• FIG. 12 is a cross-sectional view of the ultrasonic bonding anvil shoe of FIG. 10 taken along cut line B-B.[0028]
• FIG. 12[0029]bis an enlarged view of the region designated “12b” in FIG. 12.
• FIG. 13 is a front view of the combination roller and rotary cutter sub-assembly of the machine of FIG. 1.[0030]
• FIG. 14 is an end view of the combination roller and rotary cutter sub-assembly of FIG. 13.[0031]
• FIG. 15 is an end view of the rotary cutter of FIG. 13.[0032]
• FIG. 16 is a schematic side-view showing the movement of the substrate web and cut elastic components through the machine of FIG. 1.[0033]
• FIG. 16[0034]bis an enlarged view of the region designated “16b” in FIG. 16.
• FIG. 17 is a cross section of the shoe-horn apparatus, substrate web, elastic component, and a portion of the underlying combination roller taken along cut line C-C of FIG. 16.[0035]
• FIG. 18 is a perspective view of a vacuum take-off for the roller sub-assembly of FIG. 13.[0036]
• FIG. 19 is a cross-sectional view of the vacuum take-off of FIG. 18 taken along cut line E-E.[0037]
• FIG. 20 is a schematic plan view of the progress of the substrate web and attached elastic members as they move through the machine of FIG. 1, with underlying machine parts shown in dashed lines.[0038]
• FIG. 21 is a partial view of the second bonding apparatus of the machine of FIG. 1 showing a cross-sectional view of the stretched elastic member and un-gathered substrate web, taken along cut line D-D of FIG. 18.[0039]
DETAILED DESCRIPTION
• Referring to FIG. 1, a[0040]machine100 of the present invention comprises a “shoe-horn”apparatus200 extending through the center of themachine100, a combination roller androtary cutter sub-assembly300, first rotaryultrasonic bonding apparatus400, and secondultrasonic bonding apparatus500.
• The so-called “shoe-horn”[0041]apparatus200 is designed to receive asubstrate web602 and fold or gather the web to a width less than the original width of the web and to hold the substrate web in this narrower, gathered configuration while astrip610 of un-stretched elastic material is deposited onto the substrate web and bonded to it by means of a firstultrasonic bonding apparatus400. Gathering of thesubstrate web602 to a width narrower than its normal, or un-gathered width, permits depositing and bonding the elastic member on and to the gathered substrate web while the elastic member is in a relaxed or un-stretched state. This feature of the machine and process of the invention insures proper placement of the elastic member on the substrate web and prevents detachment of the elastic member from the web before the bonds holding the elastic member to the substrate web have annealed or healed.
• The manner in which the shoe-[0042]horn apparatus200 receives, gathers, and holds thesubstrate web602 can be more readily seen by reference to FIGS. 2 through 6 which show the apparatus and its components in greater detail. FIG. 2 shows the assembled shoe-horn apparatus, and FIG. 3 shows the apparatus or sub-assembly in an exploded view showing its components parts. FIGS.4-6 show the header plate in top, side, and end views, respectively.
• Referring to FIGS. 2 through 6, the shoe-[0043]horn apparatus200 comprises aheader plate202 for folding or gathering the substrate web, the header plate having anupper surface204, alower surface206, aleading edge208, a trailingedge210, first andsecond side regions207 and209, and first and second side edges212 and214. (Throughout this specification and the appended claims, the terms “leading” and “trailing,” when applied to machine components, refer to the direction of workpiece flow through the machine. “Leading” features of a machine component are up-stream in the machine from “trailing” features.)
• The[0044]header plate202 starts at itsleading edge208 as a flat member and ramps upward at an angle α to the trailingedge210. The angle α is the arc sine h/L of FIGS. 4 and 5. The values of h and L are pre-determined, based upon the initial width of the substrate web and the narrower width to which it is to be gathered or folded during processing for a particular product line to be manufactured.
• As shown in FIG. 6, the[0045]side regions207 and209 of theheader plate202 are folded downwardly, or away from thetop surface204 of the header plate at an angle α, and re-folded upwardly through the same angle β to bring the outermost surfaces of the side regions back into a parallel relationship with thecrown205 of the top surface of the header plate. This upward ramping of the header surface, and downward and outward folding of theside regions207 and209 of theheader plate202 causes the transverse dimension of thetop surface204 of the header plate to be progressively reduced from its leadingedge208 to itstrailing edge210 while theside regions207 and209 are correspondingly progressively increased from theleading edge208 to the trailingedge210. This brings the side edges212 and214 toward one another, narrowing the header plate from its initial width W₁at theleading edge208 to a narrower width W₅at the trailingedge210. At the same time, the
• As shown in FIG. 3, the[0046]header plate202 is bolted by means ofbolts216, or is otherwise fastened, to the upwardly rampingtop surface224 of acentral spine member220. A downwardly rampingtail plate240 is likewise bolted by means ofbolts248, or otherwise fastened, to the downwardly rampingtop surface226 of thecentral spine220. While the length oftail plate240 is not critical, its width, whenside regions244 and245 are folded downwardly away fromtop surface242 through an angle β, is also equal to W₅.
• When the[0047]header plate202 andtail plate240 are fastened to thecentral spine220. the open space which remains along thetop surface222 ofspine220 between theheader plate202 andtail plate240 is filled by acrown piece230. Thecrown piece230 is attached bybolts237, or other wise fastened, to a slideably adjustable crownpiece mounting member232. The crown piece mounting member is, in turn, bolted bybolts238 tospine220. Theside regions234 and236 ofcrown piece230 are folded downwardly through an angle β to conform to the trailingedge210 ofheader piece202 and theleading edge246 oftail plate240. When the shoe-horn apparatus is assembled, the ends ofcrown piece230 abut respectively the trailingedge210 ofheader plate202 and theleading edge246 oftail plate240. The upwardly rampingheader plate202,crown piece230 and downwardly rampingtail plate240 thus provide a smooth surface over whichsubstrate web602 passes during operation of the machine.
• Laterally or slideably adjustable side web guides[0048]250 and252 are bolted, respectively, bybolts254 and255 to thebottom surface228 ofspine220 directly beneathcrown piece230. First260 and second262 laterally or slideably adjustable tail portion web guides are likewise fastened, respectively bybolts268 and269 tospine220 directly beneathtail plate240. The side edge261 of tailportion web guide260 is fitted with aweb guide rod264 which extends beyond tailportion web guide260 and is bent inwardly, i.e. towards the other tailportion web guide262, at its end furthest from attachment ofrod264 to tailportion web guide262. Likewise, theside edge263 of tailportion web guide262 is fitted with aweb guide rod266 which is also bent at its end furthest from attachment to tailportion web guide262, inwardly towardweb guide rod260.
• The[0049]spine220,crown piece230, crownpiece support member232, and adjustableweb guide members250 and252 may each be of unitary construction, as shown in FIG. 2. In an alternative embodiment, any or all of these members may be split into two or more parts to aid in assembly or maintenance of themachine100.
• The cooperative interaction of the shoe-[0050]horn apparatus200 with other elements of the machine can be seen by reference again to FIG. 1. The machine comprises, in addition to the shoe-horn apparatus200, a combination roller androtary cutter apparatus300 which comprises acombination roller302 and arotary cutter352. The edge of acutting blade354 on the rotary cutter and a cutter anvil bar (306 in FIG. 7) on thecombination roller302 cooperate to cut discreteelastic members610 from the web ofelastic material608 as the web passes between therotary cutter352 and thecombination roller302. Details of the combination roller and rotary cutter are described more fully below. Thecombination roller302 androtary cutter352 are driven to contra-rotate by a meshed 1:1 gear set driven, in turn, by servo-motor380 throughright angle transmission382. The servo-motor380 is controlled byelectronic controller384.
• Servomotors having the requisite torque are commercially available. A suitable servomotor for use in the machine of the present invention is available, for example, from the INDRAMAT Division of Mannesmann Rexroth, 5150 Prairie Stone Parkway, Hoffman Estates, Ill. 60192. The servomotor is controlled by a Model DDS or HDS controller which has been programmed in the manner taught by the manufacturer using the desired speed profile for a given product.[0051]
• The speed profiles for one cycle of a process using the machine of the present invention comprises a lower dwell speed during which the[0052]elastic web608 is received oncombination roller302 and cut intodiscrete components610 by the cooperative action of the cuttingbar354 onrotary cutter352 andcutter anvil bar306 oncombination roller302. This lower constant dwell speed is maintained for a portion, preferably one-fourth, of each revolution of the combination roller and rotary cutter, and is equal to the linear speed of advancingweb608 of elastic material. The cutelastic member610 is held to the working surface of thecombination roller302 by vacuum means while the roller and attachedelastic member610 are accelerated to a second constant dwell speed equal to that of the linear speed of advancingsubstrate web602. The acceleration takes place during a portion of each revolution, preferably one-fourth revolution, of the combination roller. The second constant dwell speed is maintained for a portion, again preferably one-fourth cycle, of each rotation of thecombination roller302 while the elastic member passes through the nips betweencombination roller302 and the two rotaryultrasonic bonding horns402 and404 during which theelastic member610 is bonded to thesubstrate web602 The combination roller is then decelerated, during the final portion, preferably one-fourth cycle, of rotation of the combination roller to the first lower constant dwell speed, completing one rotation cycle.
• A graphical speed profile is constructed for the process using the linear speed of the combination roller as the ordinate of the graph, and a scale from zero to one complete cycle being the abscissa of the graph. For convenience, the four periods of each cycle of rotation (i.e. first lower constant dwell speed, acceleration, second higher constant dwell speed, and deceleration) are divided equally to each form one-fourth rotation cycle. A data table of velocity for n points along the time axis of the speed profile is generated. The resulting data table is used as the data control set for controlling the variable speed of the servomotor during each revolution of the machine rollers. For example, a data table of roller speed at each {fraction (1/2000)} revolution is constructed. These data are fed into the servomotor controller to drive the servomotor, combination roller, and rotary cutter at the desired speeds during each cycle of rotation. To convert the machine to the production of a new product with different configuration, it is merely necessary to generate a new data table for that product to drive the servomotor.[0053]
• The first[0054]ultrasonic bonding apparatus400 comprises first402 and second404 rotary ultrasonic bonding horns of the type known in the art and disclosed in U.S. Pat. Nos. 5,707,470 and 5,711,847. The horns are shown with theirrespective transducers406 and408. The first and secondultrasonic bonding horns402 and404 rotate at the same linear speec, which is the speed of the advancingsubstrate web602, and are driven byjack shaft408,pulleys410 and412 andgear belts414 and416.Jack shaft408 is, in turn, driven bypulley418 andgear belt420 by a motor, not shown.
• A second[0055]ultrasonic bonding apparatus500 is disposed downstream in the machine from the firstultrasonic bonding apparatus400. The secondultrasonic bonding apparatus500 comprised a stationaryultrasonic bonding horn502,transducer504 and arotary anvil506. The nip between the stationaryultrasonic bonding horn502 working surface and the cooperating working surface of therotary anvil506 is placed laterally between the first cylindricalweb guide rod264 attached to tailportion web guide260 and cylindricalweb guide rod266 attached to tailportion web guide262, and vertically in line with thesubstrate web602 as it advances through themachine100.
• Details of the combination roller of one embodiment of the invention are depicted in FIG. 7 where the roller is shown as[0056]302. The roller comprises ashaft portion308, abody portion304, and two vacuum cap or end plates, one of which,710 is shown. The other of the two vacuum cap or end plates is identical toplate710 and fits overshaft308 at the opposite end of theroller302. In the embodiment depicted in FIG. 8, spaced-apart first310 and second312 ultrasonic bonding anvil shoes are shown flanked, respectively, by ultrasonic bonding anvil hold-downshoes316,318, and320, and322. In a manner described in further detail below, the ultrasonic bonding anvil hold-downshoes316,318,320, and322 are bolted or otherwise fastened to thebody portion304 of the combination roller and hold the ultrasonicbonding anvil shoes310 and312 to theroller body portion304. Also shown in FIG. 7, comprising an element of thecombination roller302, is thecutter anvil bar306 which cooperates with the cutting edge of the cuttingbar354 attached to therotary cutter352 to cutdiscrete components610 from the elastic web.
• FIG. 8 shows the[0057]body portion304 of the roller with the ultrasonic bonding anvil shoes and ultrasonic bonding anvil hold-down shoes removed. Additional features of the combination roller body may be seen including vanes or stand-offs330, and332, the former having threadedholes338 for receiving bolts or other fasteners. The body portion of the combination roller has an outer surface which defines an intermittent or interrupted surface defined by the extremities of the vanes or stand-offs330, and332. While this outer surface may conform to an interrupted cylindrical, hexagonal, octagonal or other similar shape, it is preferred that the interrupted outer surface of the body portion of the roller conform to a cylinder for ease of fabrication of the ultrasonic bonding anvil and ultrasonic bonding anvil hold-down shoes. In any case, the shoes are fabricated to have an inner surface which conforms to and fits closely against the interrupted outer surface of thebody portion304 of the combination roller.
• In a particularly preferred embodiment, the body portion of the combination roller is fabricated by machining grooves, slots, or channels in a hollow cylinder of the appropriate material, preferably steel. These grooves, slots, or channels, typified by grooves or[0058]channels334 in FIG. 9, extend inwardly from the surface of thebody portion304 and run in a longitudinal direction along the length of thebody portion304. Certain of the vanes or stand-offs (for example330) are also machined to form slots orchannels336 running in a transverse direction with respect to the grooves orchannels334. These transverse channels, which may be of a depth equal to, or preferably less than, thelongitudinal channels334, permit air flow laterally between the longitudinal grooves, slots orchannels334.
• The[0059]body304 andshaft308 portions of the combination roller may alternatively be a unitary assembly fabricated by machining a single piece of material to form both the shaft and body portion, but advantages gained by forming the body and shaft portions of the roller as separate pieces make unitary fabrication less desirable. In a preferred embodiment of thecombination roller body304, the body is fabricated from a hollow cylinder which is cut or split into two pieces alonglongitudinal cuts324 and326. The body portion may, of course, be split into more than two sections, but a two-section body portion is preferred. This embodiment has the advantage of permitting affixing the body portion pieces to the combination roller shaft portion after the latter has already been assembled to the machine, thus simplifying machine set-up and maintenance. In the split, two-piece, embodiment of thebody portion304 of the combination roller shown in FIG. 8, the body portion pieces are affixed to theshaft portion308 by bolts or other fasteners passing throughholes339 and the pieces are kept from slipping on the shaft by means of key-way328 cooperating with a key (not shown) onshaft308. Thebody portion304 may be slideably moved along theshaft portion308 of the roller prior to affixing the body portion to the shaft portion. This permits variations in machine set-up to accommodate different product configurations.
• The ultrasonic[0060]bonding anvil shoes310 and312 and ultrasonic bonding anvil hold-downshoes316,318,320, and322 are depicted in greater detail in FIGS.9-12b. Both types of shoes comprise pieces having outer or working surfaces which are sections of a cylindrical surface. While the inside surfaces of both types of shoes are shown in the embodiments depicted in FIGS. 9 and 10 as also comprising sections of a cylindrical surface, the inner surface of the shoes can be of any shape which conforms to and fits closely with the outer surface of the combinationroller body portion304 as described above. Thus, when the shoes are affixed to thebody portion304 of the combination roller, regardless of their inner surface shape, they form a cylindrical outer working surface of thecombination roller302.
• A typical ultrasonic bonding anvil hold-down[0061]shoe316 is shown in FIG. 9 wherevacuum apertures375 are shown forming a pattern in the shoe. Bolt orfastener apertures374 in the hold-down shoe receive bolts or fasteners for attaching the hold-down shoes to the threadedholes338 of vanes or stand-offs such as330 in combinationroller body portion304 as shown in FIG. 8.
• As can be seen in FIG. 9 and the cross-sectional view in FIG. 11, taken along cut line A-A of FIG. 9, the edges of the anvil hold-down[0062]shoes316 are provided with inwardly-facingflanges376 and377. The term “inwardly facing” flanges means that the outer or workingsurface370 of the anvil hold-down shoes are under-cut to form the flanges such that theouter surface370 is wider than theinner surface371 of the shoes.
• The ultrasonic bonding anvil shoes are represented by ultrasonic[0063]bonding anvil shoe310 depicted in FIG. 10 and the cross-sectional view of FIG. 12 taken along cut line B-B of FIG. 10. As with the hold-downshoes316, the ultrasonicbonding anvil shoes310 are provided with a pattern of vacuum5apertures384. In addition, the outer or working surfaces of the ultrasonic bonding anvil shoes are provided with a raised pattern of stippling, shown as a pattern ofdots388 in the embodiment depicted in FIGS. 10, 12aand12b. The pattern may take any form which effectively interacts with the working surface of the ultrasonic bonding horn to form bonds between webs of materials passing between the two. The pattern of stippling is typically formed in the outer working surface of the ultrasonic bonding shoes by machining or chemically etching away a portion of the outer surface of the shoes to leave the raised stippling pattern. The resulting raised stipples388 and the etched or machined valleys between389 can be more clearly seen in the magnified view of thetop surface380 of the ultrasonic bonding anvil shoe shown in FIG. 12b. Initially the outside cylinder diameter of the pre-fabricated ultrasonic bonding anvil is a few mils (1 mil 0.0254 mm) greater than the outside diameter of the hold-down shoes. The pattern of stippling which remains on the ultrasonic bonding anvil shoes after machining or etching is thus raised slightly above the surface of the anvil hold-down shoes.
• Unlike the anvil hold-down shoes, however, the ultrasonic bonding anvil shoes are not provided with bolt or fastener holes or apertures. It has been found that when the ultrasonic bonding anvil shoes are, themselves, bolted or otherwise attached with fasteners to the combination roller body, the vibratory energy of the ultrasonic bonding horns tends to loosen or, in some instances, ultimately burn out the fasteners.[0064]
• Instead, the first[0065]382 and second383 edges of the ultrasonic bonding anvil shoes are provided with respective outwardly-facingflanges386 and387. The term “outwardly facing” flanges means that the outer or workingsurface380 of the anvil shoes are over-cut so that the outer or workingsurface380 of the anvil shoes is narrower than theinner surface381. In the assembledcombination roller302, the ultrasonic bonding anvil shoes are thus held firmly to the outer surface of thebody portion304 of the combination roller by flanking pairs of hold-down shoes. The cooperative action of the ultrasonic bonding anvil shoes and the hold-down shoes can be seen by reference to FIG. 17 which shows the shoes in cross-section.
• In assembling the anvil and anvil hold-down shoes to[0066]roller302 of FIG. 7, thefirst edge372 of hold-downshoe316 is placed against thefirst edge382 ofanvil shoe310 on theroller body304 and moved laterally so that the inwardly-facingflange376 of the hold-downshoe316 overlies the outwardly-facingflange386 of theanvil shoe310. The anvil hold-down shoe is then bolted or otherwise fastened to theroller body304. The first edge of a second anvil hold-down shoe is likewise placed against thesecond edge383 of theanvil shoe310 and moved laterally so that the inwardly-facing flange of the second hold-down shoe overlies the outwardly facingflange387 along thesecond edge383 of the anvil shoe. This second anvil hold-down shoe is likewise bolted or otherwise fastened to thebody portion304 of thecombination roller302. In a similar manner, a second ultrasonic bonding shoe is affixed to theroller body304 by flanking pairs of hold-down shoes. The cooperative interaction of the inwardly facing flanges on the bolted hold-down shoes and the outwardly facing flanges of the ultrasonic bonding anvil shoes urges theinside surface381 of anvil shoes against the outside surface of the combinationroller body portion304. In this manner, the ultrasonic bonding anvil shoes are held firmly in place on the roller body. Since the bolts or fasteners holding the anvil hold-down shoes are thus distanced from the rotary ultrasonic bonding horns, the problem alluded to above of vibratory loosening or burning off of the bolts or fasteners is considerably diminished, lengthening the period of usable life of the anvils between required machine maintenance.
• The spacer shoe(s)[0067]314 have the same construction as the anvil shoes with outwardly-facing flanges along each edge of the spacer shoes and a pattern of vacuum apertures. However, unlike the anvil shoes, the spacer shoes have a smooth outer surface and lack the raised stippling of the anvil shoes. In a preferred embodiment, the spacer shoes are made of a material lighter than that making up the anvil and anvil hold-down shoes, such as nylon, ABS plastic, or the like. This reduces the overall mass of the combination roller. The spacer shoes are fabricated in any width to appropriately space the two anvil shoes for the particular work product.
• When the anvil, spacer, and anvil hold-down shoes are thus affixed to the combination roller body, vacuum tubular channels or cavities[0068]390 (FIG. 7) are formed between theinner surfaces371 and381 of the shoes and the walls and floor of grooves, channels, orslots334 in the combinationroller body portion304 as can be seen in FIG. 7. These channels orcavities390 provide means for drawing air in through thevacuum apertures375 and384, respectively, in the anvil hold-downshoes316 and the bonding anvil shoes310. The tubes or channels permit the movement of air along the inside of the assembled combination roller assembly shown in FIG. 7, and slots or grooves335 (cf. FIG. 8) permit lateral movement between adjacent channels or tubes in the assembled combination roller.
• Referring to FIG. 7, the vacuum cap or[0069]end plate710 fits overshaft308, and an identical vacuum cap or end plate (not shown) fits overshaft308 at the opposite end of theroller302. Theplate718 is attached to theroller body304 bybolts318 passing throughbolt holes714 and received into threadedholes716 in theroller body304. Avacuum aperture712 inplate710 and a similar aperture in the plate not shown communicate with the vacuum tubes orchannels390 formed in the assembledroller302.
• The combination roller and rotary cutter sub-assembly is shown in front view in FIG. 13.[0070]Machine frame340 supports the uppercombination roller shaft308 onbearings342 and344 and the lowerrotary cutter shaft341 onbearings343 and345. The ultrasonicbonding anvil shoes310 and312 are shown oncombination roller302 flanked by and held in place by hold-downshoes316,318,320, and322 in the manner described above, and the combination roller is flanked at each end byvacuum commutators702 and704. First402 and second404 rotary ultrasonic horns are shown in partial cut-away above thecombination roller302.
• The combination roller and[0071]rotary cutter sub-assembly300 is shown in end view in FIG. 14. In addition to features described above, and assigned the same reference numerals, the end view shows a cutterblade oiler assembly902 and cutterblade oiler roller904.Gear housing808 has been removed in this view to show intermeshed 1:1 gears810 and812 driving, respectively, the uppercombination roller shaft308 and lowerrotary cutter shaft341.
• FIG. 15 shows an end view of one embodiment of the[0072]rotary cutter352. The body of the rotary cutter has been machined to have one or more flats; the embodiment shown in FIG. 19 showing four such flats, indicated as356,358,360, and362. The number of flats may vary from one to four, with one or three flats being preferred. More than four flats is theoretically possible on the rotary cutter, but such an arrangement becomes increasingly crowded.
• In FIG. 15, one of these flats,[0073]356 is shown occupied by a cutting bar apparatus which comprises a base plate364 a cuttingbar354, a cuttingbar retainer366, and retainer bolt orfastener368. The other three flats are shown unoccupied, with “ghost” cutter bar elements shown in dotted outline. As can best be seen in FIG. 16b, this arrangement permits the cuttingbar354 to strike the cuttinganvil bar306 on thecombination roller302 at an angle. This arrangement has two distinct advantages. First, the edge of the cuttingbar354 which strikes the cuttinganvil bar306, and serves as the cutting edge, is only one of four such edges on the cuttingbar354. When this edge becomes dulled or nicked during operation of the machine, it is a simple matter to turn the cutting bar to begin using a new edge. Second, the cuttingbar354 strikes theanvil bar306 at an angle and can thus flex, somewhat in the manner of a spring-board or diving board at a swimming pool. This eliminates the need for careful or precise placement of the cutting bar on the rotary cutter during machine set-up and operation.
• Details of the[0074]vacuum commutators702 and704 shown in the combination roller sub-assembly of FIG. 13 are shown in FIGS. 18 and 19 which showvacuum commutator702 in perspective and cross-sectional views, respectively. Thecommutator702 has acentral opening716 which accommodates theshaft portion308 of thecombination roller302, and a vacuum take-offtube706. Anarcuate groove712 is machined into oneface710 of thecommutator702, which subtends an arc δ. Thegroove712 is machined into theface710 of the commutator, but does not extend completely though the commutator to the other face. Thegroove712 continues inside the commutator to communicate with theopening714 in the vacuum take-offtube706 as can be seen in the cross-sectional view of commutator in FIG. 19 taken along cut line E-E of FIG. 18. As shown in FIG. 13,commutator702 abuts the end- or cap-plate fastened to the left-hand end ofcombination roller302. In a similar manner,vacuum commutator704, which is the mirror image ofcommutator702 abuts end- or cap-plate718, fastened to the right-hand end ofcombination roller302. (The designations “right-” and “left-hand” with regard tocombination roller302 refer to the front view of the roller sub-assembly shown in FIG. 13.) As the machine is operated, the cap or endplates rotate slideably, with the roller to which they are attached, againstvacuum commutators702 and704. The aperture in the cap or end-plates (for example,aperture726 in FIG. 7) communicates with the slots (for example712 in FIGS. 18 and 19) in thecommutators702 and704 during that portion of each rotation of the combination roller while the apertures are adjacent that portion of thevacuum commutator slot712 subtended by the arc δ. During this portion of each rotation, suction, externally applied to the vacuum commutators throughopenings706 and708 draw air in through the vacuum openings in the ultrasonic bonding anvil shoes, the anvil hold-down shoes, and the spacer shoe(s) making up the outer working surface of the combination roller. This air passes, internal to the combination roller, through thechannels390 in the combination roller, and out of the roller through thevacuum aperture726 in the roller vacuum cap or end-plate. During the remainder of the portion of each rotation, when theaperture726 in each cap or end-plate is adjacent to the non-slotted face of vacuum commutators, the aperture is closed off and no air can be drawn from the combination roller or commutator. In this manner, by selecting the appropriate arc δ, theweb608 of elastic material anddiscrete pieces610 cut therefrom can be held to or released from the working surface of thecombination roller302 during each any desired portion of each cycle of its rotation.
• Having thus described the principle features of the[0075]machine100 up-stream in the process of the invention, the functioning of these parts of the machine in the process will now be described. The process and machine of the invention are optimized for making articles of manufacture having an elastic member attached to a substrate web. Such articles include, for example, infant diapers and adult incontinence garments having an elastic waist band. Typically these articles comprise a moisture impervious or barrier layer which is worn nearest the garment of the user, a moisture pervious layer worn nearest the body of the user, and an absorbent layer for receiving and retaining body fluids sandwiched between. The moisture impervious or barrier layer, and the moisture pervious lay are generally wider than that of the absorbent layer. The barrier layer and moisture pervious layer are typically bonded together at each side edge to sandwich the absorbent layer between. This combination of elements, in a continuous web used in the manufacture of infant diapers and adult incontinence garments, is often termed a web “sausage” from which the individual diapers or garments are eventually cut. Such diaper or incontinence garments are also typically provided with one or more elastic waist band elements and waist tabs which serve to hold the diaper or garment to the user's body.
• In manufacturing infant diapers or adult incontinence garments using the machine and process of the present invention, a[0076]substrate sausage web602 enters the machine from the left (process up-stream side) of the machine shown in FIG. 1, passing over thelip211 of theleading edge208 of the shoe-horn header plate202 with the barrier layer of theweb sausage602 lying atop the upper surface ofheader plate202. As the web sausage moves up thesurface204 of theheader piece202, the side regions of the sausage web conform to the downwardly foldedside regions207 and209 of theheader plate202 and are, themselves, similarly downwardly folded. This folding of theweb sausage602 brings the side edges604 and606 of theweb sausage602 toward one another, resulting in the width of thesubstrate web602 being lessened compared with its original width as it comes off thesupply roller603. The dimensions of the shoe-horn header plate202 are pre-determined so that the narrowest folded or gathered width of the substrate web sausage is the same as or less than the width of the web ofelastic material608. During machine set-up, the rotaryultrasonic bonding horns402 and404 are adjusted on their bearing shaft so that the outer surfaces of the respective horns are spaced apart by a distance equal to the narrowest or folded width of the substrate web. The laterally adjustableweb guide members250 and252 on the shoe-horn folding apparatus200 are likewise adjusted so that they leave a small gap between their respective outer edges and the inside surfaces of the rotary ultrasonic bonding horns. (This arrangement can best be seen in the detail of FIG. 17.
• FIG. 17 is cross-sectional view from the down-stream process end of the machine, taken along cut line C-C of FIG. 16. The figure shows a vertical cross-section of the[0077]substrate sausage web602, cutelastic piece610, portions of the rotaryultrasonic bonding horns402 and404 the web-supportingcentral spine220 andcrown piece230 of the shoe-horn apparatus, and the anvil shoes310 and312, with their hold-downshoes316,318,320, and322 andspacer shoe314 attached to the underlying combination roller. This cross-sectional view is taken at the point where thesubstrate web602 is passing directly beneath the rotaryultrasonic bonding horns402 and404, and where a cutelastic piece610, held to the working surface ofcombination roller302, has been presented to thesubstrate web602 for bonding.
• In FIG. 17, the folded width of[0078]substrate web602 fromedge604 to edge606 is shown to be about the same as the length of the un-stretchedelastic member610 measured fromedge612 to edge614. That is to say,edge604 ofsubstrate web602 and edge612 of un-stretchedelastic member610 are matched up; similarly,edge606 ofsubstrate web602 and edge614 of un-stretchedelastic member610 are likewise matched up.
• The[0079]edge portion605 ofweb sausage602 and theend region613 ofelastic member610 are shown pressed in the nip betweenultrasonic bonding horn402 and ultrasonicbonding anvil shoe310 of the combination roller. Vibratory energy applied to thehorn402, acting against theanvil310 forms a weld or bond between theedge portion604 of thesubstrate web602 and theend region613 of the elastic member. In a similar fashion,edge region607 ofsubstrate web602 is pressed, together with theend portion615 ofelastic member610 in the nip between rotaryultrasonic bonding horn404 andanvil shoe312 and are ultrasonically bonded one to the other. This edge/end bonding of thesubstrate web602 toelastic member610 is thus carried out wileelastic member610 is in a relaxed or un-stretched state, and permits the ultrasonic bonds to anneal or heal while no stress is placed to either thesubstrate web602 or the bonded, un-stretchedelastic member616.
• In FIG. 20, the substrate web and two attached elastic members can be seen moving through the machine and process of the invention. In the region designated “A” of FIG. 20, the[0080]substrate web602 is shown after it emerges from the nips between the rotary ultrasonic bonding horns and the combination roller. with un-stretchedelastic member616 bonded tosubstrate web602 by means of first and second ultrasonic welds orbonds624 and625. At this stage of the process,substrate web602 is folded over the top ofcrown piece230, while the attached un-stretchedelastic member616 lies underweb guide members250 and252 of the shoe-horn apparatus200. This can be seen more readily by reference to FIG. 17.
• As the[0081]substrate web620 and attachedelastic member616 move into stage “B” of the machine and process depicted in FIG. 20, the substrate web moves down the upper surface oftail plate240, and tail portion webguide rod members260 and262 begin to spread the substrate web flat, stretching the attachedelastic member618 between them. At this point, the flattened, un-folded orun-gathered substrate web602 and attached, stretchedelastic member618 pass into the nip between the secondultrasonic bonding horn502 androtary anvil506. This arrangement is seen in partial cross-section in FIG. 21. As the working surface ofrotating anvil506 meets and forms a nip with stationary secondultrasonic bonding horn502, an ultrasonic weld orbond627 is formed betweensubstrate web602 and stretchedelastic member618. This weld orbond627 is formed along the length of stretched transverseelastic member618 in the region of the elastic member lying between tail portionweb guide rod264 and tail portionweb guide rod266.
• In the final stage of the process, designated region “C” in FIG. 20, the[0082]elastic member618, now fully bonded to thesubstrate web602 by both edge bonds orwelds624 and625 and central bond orweld627. is allowed to relax back to its un-stretched state by the inwardly curving ends of tail portionweb guide rods264 and266. Thesubstrate web602 with attachedelastic member618 is then subjected to further processes not forming a part of this invention, to produce the finished infant diaper or adult incontinence garment. However, it should be noted that in the embodiment shown in FIG. 20, the length of un-stretchedelastic member616 is shown to be wider than the folded width ofsubstrate web602 in order to provideside tabs620 and622. In this alternative embodiment,tabs620 and622 can be fitted in subsequent operations with mechanical or adhesive elements to function as means for fastening the diaper or garment around the waist of the user.
• While there have been shown and described what are believed to be the preferred embodiments of the invention, one skilled in the art will appreciate that various modifications may be made in the machine and process described without departing from the scope of the invention as it is defined by the appended claims.[0083]

Claims (16)

What is claimed is:

1. A machine for placing and bonding elastic members in an un-stretched state to a substrate web, said elastic members having first and second ends defining a first un-stretched length, first and second end regions respectively proximate said first and second ends; said substrate web having a longitudinal axis, first second edges defining a first width, and first and second edge regions proximate said first and second edges; said machine comprising:

a) apparatus for folding the substrate web to a second width less than said first width, and holding the gathered substrate web at said second width to receive said elastic member in an un-stretched state with the length of said elastic member being transverse to said longitudinal axis of said substrate web,

b) apparatus for bonding said first and second end regions of said elastic member respectively to said first and second edge regions of the folded substrate web while said elastic member is in an un-stretched state, leaving the remainder of said length of said elastic member un-bonded to said substrate web:

c) apparatus for stretching said bonded elastic member and un-gathering said substrate web to its first width: and

d) apparatus for bonding a portion of said remainder of the previously un-bonded length of the elastic member to said substrate web while said elastic member is in the stretched state.

2. The machine of

claim 1

wherein said apparatus for folding the substrate web comprises a header portion for folding the substrate web, a tail portion for restoring said substrate web to an un-folded condition and stretching the bonded elastic member, and a central portion disposed between said header portion and said tail portion for supporting and guiding the folded web.

3. The machine of

claim 2

wherein said header portion comprises an upwardly-ramping header plate having an upper surface, a leading edge, a trailing edge, first and second side edges, and first and second side regions respectively proximate said sides edges, said first and second side regions being folded downwardly such that the upper surface of said header plate is progressively reduced in transverse dimension from said leading edge to said trailing edge and said side regions correspondingly progressively increase in transverse dimension from said leading edge to said trailing edge.

4. The machine of

claim 2

wherein said center portion of said apparatus for folding the substrate web comprises a spine comprising a vertical element having an upper surface and a lower surface, a first end and a second end, said upper surface of said spine proximate said first end being upwardly sloped to receive said header portion of said apparatus and said upper surface of said spine proximate said second end being downwardly sloped to receive said tail portion of said apparatus, remainder of said upper surface of said spine receiving a crown for supporting said substrate web along said longitudinal centerline of said substrate web, and web guide members attached to the lower surface of said spine.

5. The machine of

claim 4

wherein said web guide members are laterally adjustable with respect to said longitudinal centerline of said substrate web.

6. The machine of

claim 2

wherein said tail portion comprises a downwardly-ramping tail plate having an upper surface, a leading edge, a trailing edge, first and second side edges, and first and second side regions respectively proximate said sides edges, said first and second side regions being folded downwardly such that the upper surface of said tail plate increases in transverse dimension from said leading edge to said trailing edge and said side regions correspondingly decrease in transverse dimension from said leading edge to said trailing edge.

7. The machine of

claim 6

wherein said tail portion further comprises first and second outwardly depending web guide members for restoring said folded substrate web and for stretching an elastic member bonded at its first and second ends to said respective first and second edge regions of said substrate web.

8. The machine of

claim 1

wherein said apparatus for bonding said first and second end regions of said elastic member respectively to said first and second edge regions of the folded substrate web comprises first and second spaced-apart ultrasonic bonding horns, a combination roller, and a rotary cutter, said first and second rotary ultrasonic bonding horns having respective first and second outer working surfaces acting cooperatively with the working surface of said ultrasonic bonding anvils on said combination roller.

9. The machine of

claim 8

wherein said machine further comprises ultrasonic bonding apparatus for bonding to said substrate web at least a portion of the remainder of said elastic member not previously bonded to said web.

10. A process for placing and bonding elastic members in an un-stretched state to a substrate web, said elastic members having first and second ends defining a first un-stretched length, first and second end regions respectively proximate said first and second ends, and said substrate web having a longitudinal centerline, first and second edges defining a first width, and first and second edge regions respectively proximate said first and second edges, said process comprising the steps of:

a) gathering the substrate web to a second width less than said first width, and holding the gathered substrate web at said second width;

b) placing an elastic member in an un-stretched state on said substrate web with the length of said elastic member being transverse to said longitudinal axis of said substrate web,

c) bonding said first and second ends of said elastic member to said substrate web adjacent the respective first and second edges of said substrate web while said elastic member is in an un-stretched state, leaving the remainder of said length of said elastic member un-bonded to said substrate web;

d) stretching said bonded elastic member and un-gathering said substrate web to its first width; and

e) bonding at least a portion of said remainder of the previously un-bonded length of said elastic member to said substrate web while said elastic member is in the stretched state.

11. The process of

claim 10

wherein said step of gathering the substrate web comprises upwardly folding said web substantially along said longitudinal centerline, thus drawing said first and second edges toward one another to gather said substrate web to said second width.

12. The process of

claim 11

wherein said first and second edge regions of said substrate web are maintained in a flat, un-folded condition while the remainder of said substrate web is upwardly folded.

13. The process of

claim 12

wherein said first and second end regions of said elastic member are placed respectively on said first and second flat un-folded edge regions of said substrate web.

14. The process of

claim 13

wherein said first and second end regions of said elastic member are bonded to said first and second flat un-folded edge regions of said substrate web while said elastic member is in a- substantially un-stretched state.

15. A process for placing and bonding elastic members in an un-stretched state to a substrate web, said elastic members having first and second ends defining a first un-stretched length, first and second end regions respectively proximate said first and second ends, and said substrate web having a longitudinal centerline, first and second edges defining a first width, and first and second edge regions respectively proximate said first and second edges, said process comprising the steps of:

a) upwardly folding said web substantially along said longitudinal centerline, thus drawing said first and second edges toward one another to gather said substrate web to said second width less than said first width, and holding the gathered substrate web at said second width;

b) placing said first and second end regions of said elastic member in an un-stretched state respectively on said first and second flat unfolded edge regions of said substrate web with the length of said elastic member being transverse to said longitudinal axis of said substrate web,

c) bonding said first and second end portions of said elastic member to said substrate web adjacent the respective first and second edges of said substrate web while said elastic member is in an un-stretched state, leaving the remainder of said length of said elastic member un-bonded to said substrate web;

d) un-gathering said substrate web and stretching said elastic member bonded at the first and second end regions thereof to said web; and

e) bonding at least a portion of said remainder of the previously un-bonded length of said elastic member to said substrate web while said elastic member is in the stretched state.

16. The process of

claim 15

wherein said first and second edge regions of said substrate web are maintained in a flat, un-folded condition while the remainder of said substrate web is upwardly folded.

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