Ultrasonic bonding apparatus

Abstract: An improved ultrasonic bonding apparatus for pattern bonding juxtaposed laminae with a pattern of discrete bonds defined by a multiplicity of discrete pattern protuberances disposed on an anvil as the laminae are forwarded in the machine direction while fixedly associated with the discrete pattern protuberances. In such apparatus having the tip of an ultrasonic transducer biased towards its anvil surface, the discrete pattern protuberances are so configured and dis­ posed on the anvil in its machine direction to obviate cobblestoning of the transducer with respect to the anvil as a patterned portion thereof is moved past the transducer tip; and/or the discrete pattern protuberances are so configured and disposed transverse the apparatus to precipitate wear -- preferably even wear -- of the tip of the ultrasonic transducer of the apparatus along the entirety of a line-of-contact portion thereof. The discrete pattern protuberances may be of various plan-view shapes including but not limited to geometrical or random shape areas, lines or closed lina­ ments and/or combination thereof. The anvil is preferably a rotatably mounted and driven anvil cylinder.

Description: Technical field This invention pertains to apparatus for ultrasonically pattern bonding together webs-particularly thin webs-to form a laminate thereof which webs are, corporately, subject to being ultrasonically bonded together. Such webs include for example, fibrous non-wovens of such materials as polyesters, and polypropylene; thermoplastic films such as polyethylene; and elastomeric films comprising such materials as butadiene/styrene copolymers. More particularly, this invention pertains to such apparatus wherein the bonding pattern is discontinuous, and wherein the ultrasonic bonding is effected on-the-fly: that is, while the webs are being forward in juxtaposed relation at a relatively high velocity. Background art Prior ultrasonic bonding apparatuses include apparatuses for convening web or sheet materials into laminates on-the-fly with predetermined patterns of bonded regions. Such apparatuses having discontinuous patterns are disclosed, for example, in U.S. Patents 3,733,238-Long et al; 3,879,256-Rust; 3,993,532-McDonald et al; 4,146,416-Goldman; and 4,311,540-Hill. Also, an ultrasonic laminating apparatus wherein the bonding pattern comprises a continuous line which closes on itself (i.e., a closed lineament) is disclosed in U.S. Patent 3,562,041-Robertson. Further, GB-A-1558401 discloses an ultrasonically bonded non woven fabric in which the bonds comprise discrete rectangular areas disposed in a bilaterally staggered array. The commonly-assigned Published European Application EP-A-84903 filed January 17th 1983 also forms part of the state of the art under Article 54(3) EPC. This discloses an apparatus for effecting discontinuous patterned ultrasonic bonding of laminae, comprising an anvil having a discontinuous patterned surface formed by outwardly facing areas of discrete pattern protuberances, said areas having a common elevation, an ultrasonic bonding transducer having a tip which is configured and disposed to contact said patterned surface along a predetermined line of contact, and drive means for moving the patterned surface of the anvil relative to the transducer tip so as to define a machine direction such that the line of contact extends transverse the machine direction, wherein the discrete pattern protuberances are so configured and disposed in said machine direction that 'cobblestoning' of said transducer tip relative to the pattern surface is obviated. However, the discovered background art has not solved all of the problems associated with such web laminating apparatus particularly with respect to tip wear. One object of the present invention is to so configure patterns of anvil protuberances that wear of the tip is distributed across its entire active width. A further object of the invention is to so configure patterns of anvil protuberances that such wear is preferably substantially evenly distributed across the entire active width of the tip whereby the frequency of needing to redress the tip is substantially reduced. Disclosure of the invention According to the present invention there is provided an apparatus for effecting discontinuous patterned ultrasonic bonding of laminae which apparatus includes an anvil having a discontinuous patterned surface corporately defined by outwardly facing areas of a multiplicity of discrete pattern protuberances and which areas have a common elevation, an ultrasonic bonding transducer having a tip which is configured and disposed to contact said pattern surface along a predetermined line-of-contact, activator means for biasing said transducer tip towards the pattern surface, drive means for moving the pattern surface of the anvil relative to said transducer tip to so define a machine direction that said line-of-contact extends transverse the machine direction and so that pattern bonding of the laminae is effected as the laminae are forwarded in the machine direction while fixedly associated with the discontinuous pattern surface, said discrete pattern-protuberances being so configured and disposed in said machine direction that cobblestoning of said transducer tip relative to the pattern surface is obviated, wherein said discrete pattern protuberances comprise bilaterally staggered arrays of protuberances wherein each array comprises rings of protuberances angularly and arcuately skewed to the machine direction and extending generally in the machine direction and rows of protuberances angularly disposed to the cross machine direction, or discrete transversely spaced, arcuate or s-shaped bars extending generally in said machine direction, said arrays or bars being so configured and disposed transverse said anvil that their machine-direction tracks sweep the entirety of the line-of-contact portion of said transducer tip, thereby to substantially evenly distribute wear thereof along said entire line-of-contact. Brief description of the drawings While the specification concludes with the claims particularly pointing out and distinctly claiming the subject matter regarded as forming the present invention. It is believed the invention will be better understood from the following description taken in conjunction with the accompanying drawings in which: Figure 1 is a somewhat schematic, side-elevational view of an ultrasonic laminating apparatus which embodies the present invention. Figure 2 is a fragmentary frontal perspective view showing the relationship between the tip of an ultrasonic transducer and an anvil cylinder of an apparatus of the general configuration shown in Figure 1, the anvil cylinder having an orthogonal array of discrete pattern protuberances on its outwardly facing surface. Figure 3 is a fragmentary side elevational view of an anvil cylinder having the tip of an ultrasonic transducer in contacting relation with the leading edge of one protuberance and with the trailing edge of a second protuberance which is circumferentially spaced from the one protuberance. Figures 4 through 6 are fragmentary plan views of laminates bearing bonding patterns precipitated by patterned anvil cylinders of ultrasonic bonding apparatuses embodying the present invention. Detailed description of the invention An exemplary web laminating apparatus 20 embodying the present invention is shown in Figure 1 to include a frame 21 (only part of which is shown); an ultrasonic transducer 23 having a tip or contact surface 25; a pivotally mounted frame assembly 26 pivoted on bearing 27 and upon which the ultrasonic transducer 23 is adjustably mounted; a rotatably mounted anvil cylinder 29 having relief-type patterned sectors 31, and non-bonding-inducing sectors 32; anvil drive means 34; actuator means 36 for biasing the ultrasonic transducer 23 towards the anvil cylinder 29; camming means 37 for spacing the ultrasonic transducer 23 outwardly from the anvil cylinder 29 in timed relation with the rotation of anvil cylinder 29 so that the tip 25 of the ultrasonic transducer 23 does not contact the non-bond-inducing sectors 32 of the anvil cylinder 29; tension isolating means 40; guide rolls 41, 42 and 43 for guiding three laminae (i.e.. webs 44, 45 and 46 respectively) onto the anvil cylinder 29; and guide roll 47 for guiding the laminated web 50 to downstream ancillary apparatus such as, for instance, reeling means not shown or a disposable diaper converting apparatus, also not shown. The apparatus may further include means for forwarding the infeeding webs under controlled tension, which means are well known to persons of ordinary skill in the art, and which means are accordingly not shown in Figure 1. Briefly, referring to the exemplary apparatus shown in Figure 1 and as will be described more fully hereinafter, the present invention provides relief-type patterned sectors 31 on the anvil cylinder 29 which sectors comprise predetermined patterns of discrete pattern protuberances. The discrete protuberances are configured and disposed to obviate cobblestoning of the tip 25 thereagainst, and to distribute induced wear across the entire line-of-contact portion (i.e., the entire width) of tip 25 to indeed, preferably, to induce substantially even wear thereacross. The line-of-contact portion has a length which extends transverse the anvil surface and is equal to the overall width of the pattern of protuberances on the anvil. This dimension is designated LOC in Figure 2. As used herein, cobblestoning is the type of bumping motion which is induced as a pressure biased member (e.g., the tip 25 of ultrasonic transducer 23) sequentially contacts spaced obstacles (e.g., discrete pattern protuberances on the anvil cylinder 29) which are spaced sufficiently apart in the machine direction that the pressure biased member goes down to a lower elevation between adjacent obstacles, and then bumps into or onto the next obstacle; i.e., in the manner a wagon wheel bumps over a cobblestone road. As will also be described more fully hereinafter, when the exemplary apparatus 20, Figure 1, is operated, webs 44,45 and 46, which are subject to being ultrasonically bonded together, are forwarded onto the power-rotated anvil cylinder 20 having a circumferential velocity which is preferably from seventy to four-hundred meters per minute so that the webs are juxtaposed and fixedly associated with a sector of the anvil cylinder and pass through a pressure biased, ultrasonic bonding passageway between the tip 25 of ultrasonic transducer 23 and the anvil cylinder 29 where the juxtaposed webs are subjected to ultrasonic vibrational energy whereupon predetermined patterned regions of the webs become bonded regions in laminate 50. The portion of laminate 50 disposed on anvil cylinder 29 is isolated from downstream tension by means 40. Figure 2 is a frontal perspective view of a cylindrical anvil 29b and a fragmentary distal portion of an ultrasonic transducer 23 having its tip 25 biased towards the anvil 29b. Anvil 29b has a multiplicity of exaggerated-size discrete pattern protuberances which are generically designated 51 disposed on its outwardly facing surface 52 in a predetermined pattern which extends about the entire circumference of the anvil cylinder. However apparatus in accordance with the invention would not necessarily need the camming means 37, Figure 1, to lift the ultrasonic transducer as unpatterned sectors of the anvil cylinder passed. This is because the pattern comprise a bilaterally staggered array of protuberances arranged in rows which are angularly disposed with respect to the cross-machine direction (i.e., transverse surface 52) and in helical rings which are angularly and arcuate pitched or skewed with respect to the machine direction (i.e., circumferentially of surface 52). While the ultrasonic transducer 23 is shown to have a tip-width which is equal to the pattern width and designated LOC, in Figure 2, it is not intended to thereby preclude the use of wider ultrasonic transducer tips. The anvil is finished so that all of the surfaces 53 lie in an imaginary right circular cylinder which is coaxial with respect to the axis of rotation of anvil 29a. Figure 2 shows an anvil 29b having an orthogonal array of protuberances 51 disposed on its outwardly facing surface 52; and a fragmentary portion of an ultrasonic transducer 23 having its tip 25 biased towards anvil 29b. Such an orthogonal pattern of discrete protuberances is shown in Figure 4a of U.S. Patent No. 4,311,540 and is considered to be prior art. Such patterns precipitate undesirable grooves in the tips of their respective transducers as the transverse spaced circular rings of protuburances track across the tips. Such patterns also precipitate what has hereinbefore been described as cobblestoning of the tip of an ultrasonic transducer biased towards the protuberances as the anvil rotates. That is, the tip bounces or bumps from one transverse row of protuberances to the next albeit the laminae are disposed therebetween. Figure 3 is a side elevational view of a fragmentary anvil cylinder 29c having an ultrasonic transducer 23 biased against protuberances 51e and 51f. These protuberances and their circumferential spacing are exaggerated to further illustrate and explain the term cobblestoning albeit the term has been defined hereinbefore. Briefly, as shown in Figure 3, tip 25 is in contacting relation with a trailing edge 60 of protuberance 51e, and with a leading edge 61 of protuberance 51f. Thus, tip 25 has moved downwardly the distance designated S since the anvil has rotated from the position where the outwardly facing surface of protuberance 51e was supporting the ultrasonic transducer; and the ultrasonic transducer will be moved upwardly distance S as the anvil rotates to bring the face of protuberance 51f under the ultrasonic transducer. In this manner, the ultrasonic transducer will cyclically move up and down through a stroke S as indicated by the arrow designated 62 as the anvil is rotated on its axis. Such motion precipitates deleterious ramifications with respect to the anvil, the ultrasonic transducer and the materials being laminated (which materials are not shown in Figure 5 in order to more clearly described cobblestoning motion). Figure 4 is a composite plan view of three machine-direction related fragmentary portions of a laminate 50b having discrete bonded regions in accordance with the present invention. The bonded regions were precipitated by a multiplicity of discrete pattern protuberances which, in the plan view, provide bonds having barrel shapes 53h, circular shapes 53j, and elongate lines 53k having longitudinally spaced lands 64. Bonded regions 53h and 53j are disposed in arcuate, longitudinally extending arrays, and bonded regions 53k are arcuate. Also, bonded regions 53h are so spaced in the machine-direction that they have a continuity of overlap in the machine direction with each other and with the ends of the elongate bonded regions 53k. The machine direction overlap evidences that the anvil protuberances were configured and disposed to obviate cobblestoning of the ultrasonic transducer; and the arcuate arrays and shapes evidence that the anvil protuberances were configured and disposed to distribute wear across the entire active width of the tip of the ultrasonic transducer. The three-fragment composite of Figure 4 shows the total curvature of the arcuate arrays of bonded regions and lines albeit their radiuses are large, and their curvatures are not readily discernable from looking at any one fragment. Such patterns have been found to be very desirable for such uses as elasticized side marginal portions of disposable diapers. These and other ultrasonic bond patterns wherein barely perceptible skewing and staggering of discrete bonded regions cause little or no functional or aesthetic problems enable the use of the present invention to obviate cobblestoning of the ultrasonic transducer, and greatly reduced rate of wear of the tip of the ultrasonic traducer. In one exemplary embodiment of the invention for making a product having a bond pattern of the configuration shown in Figure 4 the elongate anvil protuberances which precipitate bonds 53k have radii of one-hundred-thirty-two inches (3.35 meters) and machine direction lengths of eleven-and-one-half inches (29.2 cm.); the protuberances which precipitate bonds 53h have machine direction lengths of seventy-five-thousandths inches (1.9 mm.) and cross-machine direction widths of 0.1 inches (2.5 mm.); and the anvil protubernces which precipitate the circular bonds 53j have diameters of sixty-thousandths inches (1.5 mm.) and are disposed in an arcuate array having a radius of one-hundred-ninety-four inches (4.93 meters). Figure 5 and 6 are plan views of fragmentary portions of ultrasonically bonded laminates 50f, and 50g, respectively, which laminates manifest additional alternate embodiments of the present invention. Figure 5 shows a pattern of arcuate-shape-bar bonds 53r wherein arcuate-shape-bar bonds 53r are so transversely spaced relative to their curvatures that the cord of each bar bond having another bar bond disposed to its left is tangent the bar bond to its left. In a similar manner, the pattern of bar bonds 53s on laminate 50g, Figure 6 comprises S-shape bar bonds having similar cord/tangent relationships. Such relationships precipitate wear across the entire active widths of the respective ultrasonic transducers through the use of which the bond patterns were effected.

Claims: An apparatus (20) for effecting discontinuous patterned ultrasonic bonding of laminae (44, 45, 46) which apparatus includes an anvil (29, 29a) having a discontinuous patterned surface (52) corporately defined by outwardly facing areas (53) of a multiplicity of discrete pattern protuberances (31, 51) and which areas have a common elevation, an ultrasonic bonding transducer (23) having a tip (25) which is configured and disposed to contact said pattern surface along a predetermined line-of-contact, activator means (36) for biasing said transducer tip (25) towards the pattern surface, drive means (34) for moving the pattern surface of the anvil relative to said transducer tip to so define a machine direction that said line-of-contact extends transverse the machine direction and so that pattern bonding of the laminae is effected as the laminae are forwarded in the machine direction while fixedly associated with the discontinuous pattern surface, said discrete pattern-protuberances (31, 51) being so configured and disposed in said machine direction that cobblestoning of said transducer tip (25) relative to the pattern surface is obviated, wherein said discrete pattern protuberances (51) comprise bilaterally staggered arrays of protuberances wherein each array comprises rings of protuberances angularly and arcuately skewed to the machine direction and extending generally in the machine direction and rows of protuberances angularly disposed to the cross machine direction, or discrete transversely spaced, arcuate or s-shaped bars extending generally in said machine direction, said arrays or bars being so configured and disposed transverse said anvil that their machine-direction tracks sweep the entirety of the line-of-contact portion of said transducer tip (25), thereby to substantially evenly distribute wear thereof along said entire line-of-contact. An apparatus according to Claim 1 wherein said anvil (29a) is a cylinder which is rotably mounted on an axis of rotation so that said machine direction extends circumferentially about said anvil, and so that said transverse direction extends parallel to said axis of rotation.

Inventors: SCHAEFER JEAN EDWARD, SCHAEFER, JEAN EDWARD
Applicants: PROCTER & GAMBLE, THE PROCTER & GAMBLE COMPANY
Application year: 1983
Main classification: B29C65
IPC codes: B29C65