Method and Apparatus for Applying Discreet Elastic Strips to a Stationary Web

The present invention relates to a method and apparatus for securing an elastic ribbon in a stretched condition to a relatively stationary backing material or web in the manufacture of garments.

Garments such as disposable diapers include elastic waist or leg bands. The bands are constructed of an elastic ribbon material bonded to a backing material, commonly referred to as a web, such as an elastomeric nonwoven fibrous material. The bonding has been commonly accomplished by either sewing, heat activated coating on the elastic, or by the use of a separate adhesive.

The web material is relatively inelastic compared to the elastic ribbon. Commonly, the elastic material is stretched and then bonded to the web. The following patents relate to methods and apparatus for attaching discreet stretched elastic strands to portions of a web backing material. U.S. Pat. Nos. 4,642,150 to Stemmler, issued Feb. 10, 1987; 4,081,301 to Buell, issued Mar. 28, 1978; 4,504,539 to Petracek et al, issued Mar. 12, 1985; 4,353,762 to Bouda, issued Oct. 12, 1982; 4,364,787 to Radzins, issued Dec. 12, 1982; 4,464,217 to Dickover et al, issued Aug. 7, 1984; 4,479,836 to Dickover et al, issued Oct. 30, 1984; 4,525,229 to Suzuki et al, issued June 25, 1985.

The Stemmler patent shows an applicator including a supply roll for receiving and sizing elastic ribbon drawn from a supply stock. The supply roll holds the elastic tapes by a vacuum mechanism and delivers the tape to an applicator roll where the tape is stretched. The stretched elastic tape which is held on the surface of the applicator roll by a vacuum is then transferred to a web surface for bonding by an adhesive.

The Buell patent discloses the stretching of an elastic ribbon to a desired value by adjusting the speed of the rolls through which the elastic ribbon is guided before proceeding to a bonding station where the stretched elastic is adhesively bonded to a web backing material.

The Petracek et al patent discloses ultrasonic bonding of fibers and yarns to a nonwoven web surface.

Problems arise in effectively transferring a stretched elastic member to a position adjacent the web backing material for bonding. The elastic material must be maintained in a predetermined tensioned state while being positioned relative to and brought in contact with the web for a bonding operation.

It is further desirable to utilize an apparatus that can apply a stretched elastic member to a web backing in either a straight line or in a curved pattern while maintaining the elastic material in the predetermined tensioned state.

It is further preferable to utilize ultrasonic bonding to bond the elastic material to the web backing support. Ultrasonic bonding is capable of delivering a high bonding energy in a shorter period of time with less bond registration variations, resulting in a more accurate and efficient process when compared to thermal bonding. With respect to bonding the preferred materials of the nonwoven fibrous web, ultrasonic bonding enables penetration of the web by the ultrasonically generated frictional heat, melting the polymeric fibers of the web better than thermally generated bonds. Autogenous bonding, that is, ultrasonic or thermal bonding, requires compatible melt temperatures of those polymers comprising the materials sought to bonded together.

The present invention provides an efficient mechanism for ultrasonically bonding a stretched elastic material to a web backing material. The present invention further provides an efficient means for transferring a stretched elastic material to a anvil for ultrasonic bonding while maintaining the elastic material in the stretched condition.

The present invention provides an apparatus for applying an elastic material to a backing material, the apparatus including applicator means for applying a length of the elastic material to a bonding support means, bonding support means for supporting the length of elastic material relative to the backing material for a bonding operation, and bonding means for bonding the length of elastic material to the backing material. The applicator means includes tensioning means for applying a tension to the length of elastic material and retaining means for selectively retaining the length of tensioned elastic material and releasing the length of tensioned elastic material to the bonding support means.

The present invention further provides a method of applying an elastic material to a backing material, the method including the steps of placing the length of elastic material under tension, applying the length of elastic material to a bonding support surface while maintaining the elastic material in tension, and bonding the length of tensioned elastic material to the backing material.

Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is an elevational view of the present invention;

FIG. 2 is an enlarged plan view taken substantially along lines 2--2 of FIG. 1;

FIG. 3 is a cross sectional view taken substantially along lines 3--3 of FIG. 2;

FIG. 4 is a view taken substantially along lines 4--4 of FIG. 2;

FIG. 5 is a fragmentary elevational view of the present invention highlighting the applicator means in the retracted position;

FIG. 5a is an enlargement of the applicator means in the retracted position highlighted in FIG. 5;

FIG. 6 is an elevational view of the present invention highlighting the applicator means applying a length of tensioned elastic material to the bonding support plate;

FIG. 6a is an enlargement of the highlighted portion in FIG. 6;

FIG. 7 is an elevational view highlighting the applicator means fully extended relative to the bonding support plate;

FIG. 7a is the highlighted portion of FIG. 7;

FIG. 8 is an elevational view of the present invention highlighting the bonding support plate brought into proximity of the backing material and the ultrasonic horns brought into contact with the other side of the backing material;

FIG. 8a is an enlarged fragmentary elevational view of the highlighted portion of FIG. 8 highlighting the bonded materials between the anvil and ultrasonic horn;

FIG. 8b is an enlarged fragmentary cross sectional view of the highlighted portion of FIG. 9a;

FIG. 9 is a plan view of the bonding support plate;

FIG. 10 is a fragmentary cross sectional view taken substantially along lines 10--10 of FIG. 8;

FIG. 11 is fragmentary cross sectional view taken substantially along line 11--11 of FIG. 9;

FIG. 12 is a side elevational view of the drive roll of the applicator means in frictional contact with the raised portion of the bonding template; and

FIG. 13 is a plan view showing the applicator means on the raised portion schematically shown as dash lines.

An apparatus for applying an elastic material to a backing material is generally shown at 10 in the Figures. The apparatus 10 generally includes applicator means generally indicated at 12 for applying a length of elastic material 14 to a bonding support plate, bonding support means generally indicated at 16 for supporting the length of elastic material 14 relative to a backing material 18 for a bonding operation, and bonding means generally indicated at 20 for bonding the length of elastic material 14 to the backing material 18.

One aspect of the present invention provides the applicator means 12 with tensioning means for applying a tension to the length of elastic material 14 and retaining means for selectively retaining the length of tensioned elastic material 14 and releasing the length of tensioned elastic material 14 to the bonding support means 16. More specifically, the applicator means 12 includes a pair of roll assemblies 22,24 shown in FIG. 2, for simultaneously applying two lengths of the elastic material 14 to the bonding support means 16. Each of the applicator roll assemblies 22,24 includes a drive roll 26 operatively connected through gears 28 and 30 to a tensioning roll 32.

The tensioning means includes the drive roll 26 which has a predetermined diameter and the tensioning roll 32 operatively driven by the drive roll through the gearing 28,30, the tensioning roll 32 having a smaller diameter than the drive roll 26. The assembly 10 includes stay roll 36 positioned adjacent the tensioning roll 32, the tensioning roll 32 imparting a preselected tension to the elastomeric material 14 held between the tensioning roll 32 and stay roll 36 as the elastic material 14 is drawn by the drive roll 26 as described below.

The assembly 10 further includes a guide roll 39 adjacent the drive roll 26, opposite the tensioning roll 32. The stay roll 30 and guide roll 39 each are rotatable in only one direction, that is, when the applicator roll assembly 12 is operated, the stay roll 36 and guide roll 39 rotate with the clockwise movement of the drive roll 26. The stay roll 36 and guide roll 39 prevent the drive roll 26 from rotating in the counterclockwise direction, thereby keeping the elastic material 14 from backing out of the applicator assembly 12 through which the elastic material 14 is threaded.

The retaining means includes a retainer surface 34 on the drive roll 26. The retaining means further includes a vacuum source 43 in communication with a hollow inner core 38 of the drive roll 26 through manifolds 41. Openings 40 extend from the inner core 38 to the retainer surface 34 for operatively conducting the vacuum to the retainer surface 34.

The drive roll 26 includes release means for releasing the elastic material 14 from the vacuum means. The release means includes a plate member 42 fixedly supported within the core 38 of the drive roll 26. The drive roll 26 is rotatable relative to the fixed plate member 42. The plate member 42 is positioned within the inner core 38 adjacent the inner surface of the rotatable drive roll 26 so that the plate member 42 covers the adjacent ones of the openings 40 as the drive roll rotates, the plate member 42 thereby blocking the vacuum to the ones of the openings 40 to release the elastic material 14 from the respective retaining surface 34. As oriented in the Figures, the openings or vacuum apertures 40 are blocked off by the plate member 42 from about the 12 o'clock to about the 3 o'clock positions, resulting in the vacuum being applied by the drive roll 26 to the elastic material 14 where the openings 40 are not blocked, and releasing the elastic material 14 from the retaining surface 34 where the openings 40 are blocked. Thusly, the vacuum through the openings 40 retains the elastic material in the tensioned condition on the retainer surface 34 and the plate member 42 releases the elastic material 14 from the retainer surface 34. In this manner, the applicator assembly 12 provides means which first places the elastic material 14 in tension and then retains the elastic material in the preselected tension until it is released from the drive roll 26.

The applicator assembly 12 is mounted on a support 44. The applicator assembly 12 applies the discrete length of material 14 onto the bonding template 16 as the applicator assembly 12 is moved between a retracted and an extended position. The assembly 12 includes tracking means for tracking the assembly 12 along a curvalinear path between the two positions as the assembly 12 applies the material 14 along the path. The tracking means is universally adjustable to follow either a curved path or straight line path during the application procedure.

The support 44 is a slide block seated for sliding movement on a pair of rods 47,49. The rods 47,49 are mounted on an end portion 46 of an arm assembly generally indicated at 48. The rods 47,49 are secured to the end portion 46 by fastening portions 50.

The arm assembly 48 provides the assembly 10 with applicator extending and retracting means for extending and retracting the applicator means 12 relative to the bonding support means 16 as the applicator means releases and transfers the length of tensioned elastic material 14 to the bonding support means 16. The extension and retraction can occur over a curved or straight line path.

The extending and retracting means includes a retractable arm assembly comprising a plurality of arms 56 connected at joints 58,60,62 and drive means for moving the arm assembly 48 along an infinite path directing the applicator means 12 on a selected path adjacent the bonding support means 16. The arm assembly 48 is mounted on the assembly support structure generally indicated at 64 and is retractable relative to the support structure 64 to remove the applicator means 12 from between the bonding support means 16 and the bonding means 20.

The support structure 64 includes a plurality of vertically extending support posts 66,68,70,72 and a plurality of horizontally disposed supports 74,76. The arms 56 are guided through a guide housing 78 mounted on a horizontally disposed support beam 80. The housing 78 includes openings 82 therethrough through which the arms 56 extend. As shown in FIG. 2, the arm assembly 48 may include a plurality of arms 56 supporting the applicator 12.

The bonding support means 16 comprises a bonding template 16 connected to a vacuum source 84 through manifold 86. The bonding template 16 is moveable along guides 88,90 in a vertical direction by extension and retraction means 92. The extension and retraction means 92 can be a hydraulic mechanism comprising a fluid cylinder 92 for driving retractable and extendable piston 94 operatively connected to the bonding template 16.

The bonding template 16 includes a pair of raised support paths 96. The support paths 96 may be linear, as shown in FIG. 9 at 96 or may be curvalinear as shown at 96' in FIG. 13. Each support path 96,96' defines a path onto which the length of the tensioned elastic material 14 is transferred.

The tracking means of the applicator means 12 includes follower means for following the paths 96,96' as the elastic material 14 is transferred from the applicator means 12 to the path 96,96'. More specifically, the raised support path 96,96' is a raised surface including holding means for holding the length of the tensioned elastic material 14 in the tensioned condition once it is transferred from the applicator assembly 12. The holding means includes the vacuum source 84 which is in communication with the raised surfaces 96,96' through openings 98. The vacuum selectively holds the length of tensioned elastic material 14 against the raised surfaces 96,96' and maintains the elastic material 14 in the tensioned condition upon transfer from the applicator means 12.

The follower means of the applicator assembly 12 includes the annular recessed surface 34 of the drive roll 26 and annular walls 100,102 on each side of the recessed surface 34 defining an annual channel for rolling mating engagement with the raised portion 96,96'. The mating engagement is shown in FIG. 12.

The tracking means further includes a universal support for supporting the drive roll 26 through simultaneously forward, lateral, and rotational translation thereof relative to the bonding template 16. The drive roll 26 is mounted on an axle 51 operatively connected to the slide block 44 for rotational movement relative thereto. Fasteners 53 and bearings 55,57 connect the axle 51 to the block 44. Spring 59 biases the axle 51 and connected drive roll 26 to a neutral position. In the neutral position, the drive roll 26 is positioned to initially matingly engage the origin of the raised portion 96,96'.

In operation, the arm assembly 48 extends the applicator assembly 12 so that the drive rolls 26 engage the origin of the tracks 96,96'. As shown in the Figures, the applicator assembly 12 includes a pair of drive rolls 26. The drive rolls 26 are in the neutral position, as shown in FIG. 2 wherein the rolls 26 track in a direction substantially perpendicular to the rods 47,49. When the applicator assembly 12 is used with a bonding template 16 as shown in FIG. 9, wherein the template 16 includes straight tracks 96, the recessed portion 34 ride on and engage the raised portions 96 and follow the straight line thereof. As shown in FIG. 13, as the applicator assemblies 12 engage and follow a curved track 96', the applicator assemblies 12 translate laterally as shown by arrows 61,63 along the rods 47,49. The applicator assembly 12 translates in the forward direction, as indicated by arrows 65 by extension of the arm assembly 48. The applicator assemblies 12 translate rotationally as indicated by arrows 67,69 by rotation of the axles 51. Accordingly, the combination of the connection of the applicator assemblies 12 to the rods 47,49, to the axles 51, and to the arm assembly 48 provides for universal forward, lateral, and rotational movement of the applicator assemblies 12 so that they can follow an infinite variety of curvalinear paths. Thus, the present invention provides an applicator assembly which can apply a discrete length of elastic material to a bonding template, and eventually to a backing material, in an infinite variety of forms.

The bonding means 20 includes a pair of ultrasonic horns 104,106, each horn 104,106 supported on a hydraulic actuator 108,110, respectively for actuating vertical movement of the horns 104,106. The raised surfaces 96,96' include metallic projections 112 defining anvil means for cooperating with the ultrasonic horns 104,106 to bond the tensioned elastic material 14 to the backing material 18 by ultrasonic bonding as discussed below.

The support structure includes roll supports 114,116 for supporting rolls of backing material sheets 18 on a path between the bonding template 16 and the ultrasonic horns 104,106. The support structure 64 supports the bonding support means 16 and ultrasonic horns 104,106 for reciprocating movement towards and away from the path of the sheet of backing material 18 when the applicator means 12 retracted to thereby sandwich the backing material 18 between the bonding template 16 holding the length of tensioned elastic material 14 and the ultrasonic horns 104,106.

The backing material 18 is an elastomeric nonwoven fibrous material, carried either on a tentered frame or a vacuum belt which supports the backing material under minimal tension along the opposed margins thereof and in the stationary position relative to the bonding template 16 and ultrasonic horns 104,106.

The present invention further provides a method of applying the elastic material 14 to the backing material 18, the method generally including the steps of placing the length of elastic material 14 under a predetermined tension, applying a length of elastic material 14 to the bonding support surface 16 while maintaining the elastic material 14 in tension, and bonding the length of tensioned elastic material 14 to the backing material 18.

More specifically, and as illustrated through the sequential drawings in FIGS. 2 through 8a, the elastic material 14 is threaded from a source (not shown in the drawings) through between the tensioning roll 32 and stay roll 36, around the drive roll 26 between the guide roll 39 and held on the drive roll 26 beyond the guide roll 39 by the vacuum mechanism 43 through the manifold 41.

The arm assembly 48 extends the applicator assembly 12 so that the drive roll 26 is moved adjacent to the raised portion 96 on the bonding support surface 16. The elastic material 14 which is in the tensioned condition as it is threaded around the drive roll 26 and maintained thereby by the vacuum communicated through the openings 40 is sandwiched between the drive roll 26 and raised surface 96,96'. The drive mechanism of the arm assembly 48 moves the applicator assembly 12 so that the frictional engagement of the drive roll 26 against the bonding support surface 16 rotates the drive roll 26. As the drive roll 26 rotates the elastic material 14 is drawn from between the tension roll 32 and stay roll 36 and about the drive roll 26 and fed onto the raised surface 96,96'. As shown in FIG. 6a, the elastic material 14 is held on the drive roll 26 by the vacuum through the openings 40 until the elastic material is both in contact with the raised portion 96 and the adjacent opening 40 is covered by the plate member 42. At this point, there is no longer a vacuum holding the elastic material 14 on the drive roll 26 and the vacuum communicated through the openings 98 maintains the tensioned elastic material 14 on the raised portion 96 in the tensioned condition. In other words, the transfer of the tensioned elastic material is perfected through the combination of the vacuum means through the drive roll 26 being excommunicated by the plate member 42 coincidently with the tensioned elastic material 14 coming into contact with the vacuum effected through the openings 98 in the raised surface 96 of the template surface 16.

As the applicator assembly 12 reaches the end of the raised portion 96, a knife mechanism 124 cuts the length of elastic material 14 thereby leaving on the raised portion 96 a predetermined length of elastic material 14 which is in a tensioned condition and in a predetermined configuration.

As shown in FIGS. 8 and 8a, the applicator assembly 12 is retracted to a position which is no longer between the bonding support means 16 and the bonding means 20. The backing material 18 is led from roll 114 to 116 and is held relatively stationary relative to the disposed tensioned elastic material 14. In order to bond the tensioned elastic material to the backing material 18, the hydraulic mechanism 92 lowers the bonding support plate 16 so that the tensioned elastic material comes in contact with the backing material 18. Concurrently, the hydraulic mechanisms 108,110 raise the ultrasonic horns 104,106, respectively, to contact the backing material 18 from the opposite side. The raised projections 112 function as an ultrasonic bonding anvil when the tensioned elastic material 14 is held poised on the projections 112 and brought into contact with the stationary elastomeric backing material 18 during activation of the ultrasonic horns 104,106. After the materials 14 and 18 are bonded together, the ultrasonic horns 104,106 are lowered. The bonding template 16 is raised leaving the tensioned elastic material on the backing material. The rollers 114,116 are moved to dispose a new length of backing material 18 between the bonding template 16 and ultrasonic horns 104,106 and the process is repeated.

The invention has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims wherein reference numerals are merely for convenience and are not to be in any way limiting, the invention may be practiced otherwise than as specifically described.