METHOD AND APPARATUS FOR MAKING A PILE ARTICLE AND THE PRODUCTS THEREOF

The present invention relates to elongated pile articles that are useful as floor and wall covering when aligned with other elongated pile articles and attached to a backing substrate to make up a pile surface structure, and to methods of making an elongated pile article and a mandrel system useful in the process for making the article.

This invention is an improvement over the invention of US-A-5 472 762 which teaches an improvement over existing elongated pile articles and methods of making them.

Conventionally, elongated pile articles have been made for use as a chenille-type yarn, as a pile weatherstripping, or made as part of a carpet-sized x-y array of support strands and pile yarn that emerges from the process as a finished carpet. The chenille-type yarns do not lend themselves to assembly into a carpet structure except by a time consuming expensive weaving process. The weatherstripping articles do not provide individual bundles of bulky yarn along a strand and are not designed to be made by a process using a continuous yarn source, and are not designed with a narrow strand for compact side-by-side assembly. The carpet-sized x-y array process is a complex process where it is difficult to control the process tension and bonding quality of individual pile articles, and it does not produce pile particles that can be used in a carpet to produce a high density of tufts/square inch. The strand width and pitch of the yarn on the strand are large compared to the diameter of the yarn bundle used. The process also does not lend itself to producing an intermediate upstanding pile article that can be packaged and sold as a feed material to carpet makers. The pile articles made by the x-y array process usually employ an adhesive to attach the yarn to the support strand and the pile article to a backing which adds another polymer component to the structure and is messy, difficult to process, and presents problems when the base materials of the article are to be recycled after use.

US-A-5 472 762 corresponding to WO-A 9 419 521 constituting prior art in the sense of Article 54(3) EPC, teaches a low cost elongated pile article comprising bundles of yarn arranged in a high density along an elongated strand. The product can be made by a simple inexpensive method where yam is wrapped over a mandrel guiding the strand and an ultrasonically energized horn is used to continuously compact and bond the yarn to the strand. This product comprises a cut pile article or a loop pile article having a single row of loops associated with each strand. The elongated pile article product can be packaged separately for later use or used directly as a feed material for combining with a backing substrate for making a pile surface structure. (The word "row" is used in a general sense and as suggested on page 26, line 24 and following.)

The invention as claimed seeks to solve the problem of providing a loop pile making process and product for making a higher density elongated loop pile product, and especially one that has more than one row of loops associated with each strand. It also seeks to provide a loop pile making process tat can be easily varied to change the height of the loops, and it seeks to provide a loop pile making process and product for speciality loop pile products.

The pile article of this invention comprises a plurality of yarns comprising filaments attached to a support strand wherein each yam is in the form of a pair of loops bonded to the strand, with one of the pair on each side of the strand. In another embodiment, the loops on one side of the strand are a different length than the loops on the other side of the strand. In still another embodiment, a loop pile article is made from twisted yarn that plies together after looping to make a pair of plied loops on each side of the strand. In a further embodiment, some of the pairs of loops are cut whereby some of the yarns on the tuftstring comprise a pair of loops with one on each side of the strand and some of the yarns comprise cut pile tufts. In yet another embodiment, the yarn comprises a plurality of strands with at least one strand different from the others for a special visual effect, such as when different colored strands are used and a low level of twist occurs in making the product so different colors disappear and reappear in the paired loops.

The invention is also a pile surface structure similar to the pile surface structure of US-A-5 472 762 except the pile articles attached to a backing substrate to make a pile carpet are the novel loop pile articles of this invention.

The invention is also a method of making a loop pile article, comprising contacting a support strand with a plurality of yarns comprising filaments, wherein each yarn comprises a pair of loops with one on each side of the strand; bending the yarns over the strand; and bonding the filaments of each yarn where they contact the strand to form a dense portion in the yarn that has the filaments bonded together and to the strand.

In a preferred embodiment, the method comprises feeding a continuous length of yarn comprising filaments under tension to an eccentric guide, rotating the guide to wrap the yarn around a fork to form loops of the yarn, with the fork having a plurality of prongs having one end free of support, positioning the prongs on the sides of a mandrel having an elongated ridge on the mandrel between the prongs, feeding a carrier strand for the loops along the mandrel and guiding the carrier strand along the ridge between the loops and the stationary mandrel; said carrier strand optionally being the support strand when the support strand is placed between the loops and the stationary mandrel; transporting the loops under a bonding means aligned with the ridge and the support strand by propelling the carrier strand along the ridge of the stationary mandrel; bending the loops over the ridge; bonding the filaments in the yarn to each other and to the support strand while bent over the ridge to form a loop pile article; forwarding the bonded loops off the free end of the prongs; and forwarding the pile article off the mandrel.

Brief Description of the Drawings

• Figure 1 is a diagrammatic view of the process for making an elongated pile article;
• Figures 2A, 2B and 2C are perspective and different end views of an elongated pile article with cut pile yarns;
• Figures 3A and 3B are end views of an alternate embodiment for the pile article of Figures 2B and 2C, respectively;
• Figure 4 is a diagrammatic illustration of a method of making a carpet from the elongated pile article having a cut or loop pile;
• Figure 5 is a schematic plan view of a loop pile elongated pile article;
• Figure 6 is a perspective view of the loop pile elongated pile article of Figure 5;
• Figure 7 is a diagrammatic view of a process for making the loop pile article of Figure 6;
• Figure 8 is an end view of an alternate embodiment of the loop pile article of Figure 6; and
• Figure 9 is a perspective view of another embodiment of the loop pile elongated pile article.

Detailed Description of Illustrated Embodiments

The process and product made in US-A-5 472 762 are similar in many respects to the present invention especially in the manner of using a yarn wrapper, a mandrel acting as an ultrasonic anvil, a carrier strand and support strand; and in details of the bond between the yarn and support strand. The manner of taking a tuftstring and attaching it to a backing material is the same whether dealing with the tuftstrings in US-A-5 472 762 or the improved loop-pile tuftstrings of this invention. Since many concepts and language to describe this invention are shared with US-A-5 472 762, it is necessary to review below Figures 1-3 and Figure 7 which describe the tuftstring and carpet from US-A-5 472 762.

Referring to Figure 1, a yarn 20 is fed into the process from a source at 22 through tensioner 24. The yarn may typically be a multifilament, crimped, bulky, plied-twisted yarn that has been heat set to retain the ply-twist. The yarn is a thermoplastic polymer, such as nylon, polypropylene, etc. The yarn may be one or several ply-twisted lengths; two lengths are shown. The yarn 20 passes through a hollow guide conduit 26 that is rotated about its center. The conduit is bent to guide the yarn to a position at 28 radially displaced from the center of rotation. A mandrel 30 is supported and held stationary at the center of rotation by fixed support 29 and accepts the yarn which is wound around the mandrel as it is fed from the conduit at 28. A slight twist may be imparted to the yarn as it passes through the rotating conduit so if two strands are used for the yarn source, the strands may have a low pitch wrap about one another as they leave the conduit at 28.

A support strand 32 is fed into the mandrel at 34 and through a passage 36 in the mandrel. The strand exits the passage at 38 where it is guided to the outside of the mandrel along ridge 40. The mandrel may have two, three, four or more such ridges where the yarn wrapping on the mandrel bends at an included angle between 0 and 180 degrees, preferably less than 90 degrees. A star-shaped mandrel with means to guide the yarn down between the peaks may be used to provide more than four ridges with the yarn bent to less than 90 degrees around the ridge. The yarn 20 is wrapped over the strand 32 which is pulled along the mandrel by the windup 41. Additional strands or yarn carriers, such as 134 and 136 propelled by motor driven pulley 135, are used to transport the yarn along the other ridges of the mandrel. It is important for controlled, uniform yarn movement that such transport means are provided for the yarn along each ridge of the mandrel. The yarn is wrapped under some tension so it conforms to the mandrel and is frictionally engaged with the strand and carriers for transporting before and after bonding. Frictional engagement with the strand the yarn is bonded to is not necessary after bonding. The wrapped yarn and strand travel together along the mandrel and under ultrasonic horn 42 where sufficient energy is imparted to the yarn that it is compacted, the multifilaments are fused together, and the yarn is fused to the support strand. When the yarn is bonded while bent around the mandrel, the yarn remains bent at the mandrel angle when removed. This bend is especially noticeable in the bundle filaments adjacent the bond that were pressed directly against the mandrel. The mandrel ridge 40 acts as an ultrasonic anvil surface. The wrapped yarn, now bonded to the strand, continues along the mandrel to cutter 44 (intermediate the mandrel ridges 142 and 150 and inserted in a cutter slot 47 in the mandrel) which severs the yarn to define individual bundles of yarn having opposed ends with each bundle attached to the strand intermediate the ends. The cut bundle is attached to one side of the strand at a location on the periphery of the strand and the ends are bent at acute angles at a base 73 to define two legs or tufts. The acute angles are measured relative to a reference plane 71 tangent to the location along the strand where the bundles are attached. The cut yarn unwraps from the mandrel between ridges 142 and 150 and allows access to the mandrel for mandrel support 29 and to feed in the strand at 34 as discussed. The basic elongated pile article or tuftstring 45 of Fig. 1 is now complete and can be wound up on a reel, piddled into a container, or fed directly to another piece of processing equipment.

Figs. 2A, 2B, and 2C show different views of a typical elongated pile article (tuftstring) 45 of the invention. Figure 2A shows a plurality of bundles of yarn 46, 48, 50, etc. bent in a "U" shape and attached to a support strand 32 at the inside of the "U". The bundle is bent to define a pair of upstanding legs or tufts 52 and 54 for bundle 46, the tufts attached at their base 73 to the strand 32. The cut ends 56 and 58 of the tufts 52 and 54 respectively fall in a plane common with the ends of the other tufts, although the ends may fall in different planes for different special effects.

Fig. 2B shows an enlarged partial end view of the tuftstring of Fig. 2A and Figure 2C shows the tufts of Fig. 2B bent down to better study the bonded region; both figures show details of the bond of the bundle 46 to the strand 32. The bundle has, along its length, a compacted region of multifilaments 60 that has a dense portion 62 with the filaments bonded together, and opposed side portions 64 and 66 with surface filaments, such as at 68, set at acute angles 70a and 70b to the reference plane 71 at the base of the tufts.

The opposed side portions 64 and 66 lie next to, and on either side of, the dense portion. The dense portion has a width 72 that approaches the width 74 of the strand 32; the dense portion is bonded to one surface portion 76 of the peripheral surface of the strand 32. The width of the strand is the distance across the strand perpendicular to the strand length and parallel to the reference plane 71.

The strand is shown in the preferred position which is on the inside of the "U" shape, but the strand and bundle can also be attached with the strand on the outside of the "U" shape as is shown in Figs. 3A and 3B. The characteristics of the bonded region remain the same as described with reference to Figs. 2B and 2C. To produce the elongated pile article of Figs. 3A and 3B, strands 32, 134 and 136 would be carrier strands, not bonded to the yarn, which would be made of a material having a higher melting point than the yarn (for instance, Kevlar® aramid fiber by Du Pont used with a yarn such as nylon) and the yarn 20 would be wrapped around the carriers and mandrel 30. A support strand 32a would be fed onto the yarn at the horn 42 and bonded to the yarn. The horn would have a shallow groove in the surface aligned with ridge 40 to guide the strand during the bonding operation.

The bonded region of the bundle has a structural feature that is important to the function of the elongated pile article when a plurality of them are assembled on a backing substrate to form a pile surface structure, or carpet. When a force is applied to a tuft (leg) of the pile article of the invention, the tuft breaks at the edge of the bond to the strand before the tuftstring pulls away from the backing substrate, i.e., the bundle is frangible adjacent each end of the dense portion 62. This is desired so major damage does not occur to the pile surface structure if a single tuft is snagged during use, such as by a vacuum cleaner, household pet, childs toy or the like. Loss of a single tuft would not be noticed in the carpet, but pull-out of a portion of a tuftstring by breaking the attachment to the backing would be very noticeable and would have to be timely repaired to prevent further damage. This feature of the tuftstring of the invention is achieved by proper bonding of the yarn bundle 46 to the strand 32 at the dense portion 62 of the compacted region 60 of the bundle. When done properly, the filaments at the edges of the width 72 of the dense region are thinned out at a frangible portion of the bundle at the base of the tuft, such as at 98 and 100, so the strength of the frangible portion is weaker than the strength of the bundle before bonding. It may also be desirable to have a single tuft pull off of the strand than to have the bundle separate from the strand thereby removing two tufts. When a single tuft on a conventional tufting-machine-made cut pile carpet is pulled, two tufts are removed. This can be avoided on a tuftstring-made carpet by making the frangible portion strength less than the strength of the bond between the bundle and the strand. That is, the tensile strength of the bundle is less than the shear or peel strength of the bond between the bundle and the strand. When one leg, or tuft, of the bundle is pulled it will fail by breaking at the thinned out frangible portion at the tuft base. If the bond is too weak, pulling on a single tuft may break the bond between the bundle 46 and the strand 32 and the entire bundle 46 including both tufts or legs 52 and 54 will come off the strand. This would be more noticeable in the pile surface structure than loss of a single tuft. If the bond is too strong and the bundle is lacking the frangible portion, pulling on one tuft allows the yarn bundle wrapped around the strand to act as a unit that may possibly pull the tuftstring away from the carpet backing.

The ultrasonic bonding can be controlled for instance, by varying the ultrasonic energy applied to the horn, the pressure between the horn and yarn, and the time a yarn bundle spends squeezed under the ultrasonic horn. Other variables, such as horn tip shape, ultrasonic frequency, and the addition of ultrasonic energy coupling agents (finishes) to the yarn filaments, can also be controlled. The bonding process for a given yarn can be varied to produce different density bonds having different thicknesses to achieve the desired frangibility. The density of the dense region of the bond may approach the density of the yarn polymer as the filaments are tightly squeezed together and heated by the action of the ultrasonic horn. It has been observed in some cases that the proper balance (between the frangible portion strength and the bundle-to-strand bond strength) occurs when there is some polymer "flash" or "debris" evident at the edges of the dense region of the bundle on the side where it contacted the ultrasonic horn. For example, a 2750 dtex (2500 denier) two-ply twisted strand had a frangible strength less than the bond strength when bonded with an ultrasonic driver at 40 KHz freq. and 0.025-0.05mm (1-2 mil)/amplitude for about 1.0 second with a force of about 22.6N (5 pounds) between the horn and yarn. An ultrasonic driver that works well in this application is a Dukane Corp. model 40A351 power supply capable of 350 watts at 40 KHz, connected to a Dukane Corp. 41C28 transducer. A Dukane booster may also be used.

Bonding means other than ultrasonic bonding may be employed on the compacted portion of the bundle to bond the filaments to each other and to the strand. Such means may be solvent bonding or thermal bonding with, for instance, a hot bar; or some combination of solvent, conductive, and ultrasonic bonding.

An embodiment for making loop pile tuftstring is schematically shown in Fig. 5 where the pile yarn 20 is looped and placed over the strand 32. The loops would be bent at an angle over the strand, and the loops and yarn would be passed under an ultrasonic horn that would bond the bent yarn to the strand where the loops cross the strand. This would produce the loop pile tuftstring structure in Fig. 6 having upstanding loop tufts on both sides of the strand, such as the U" shaped bundle that forms a pair of loops 300 and 302, on the right and left sides of strand 32, respectively. The yarn at the base of the "U" shaped, upstanding loop, tufts would have the same characteristics as the cut pile tuftstring structures described above, such as the compacted region of multifilaments that has a dense portion with the filaments bonded together, and opposed side portions with the surface filaments set at acute angles to a reference plane at the base of the tufts. In the cut pile tuftstring, the bundle was defined by the U-shaped length of yarn between the cut ends of two connected tufts. In the case with loop pile where there are no cut ends, the bundle is defined as the U-shaped length of yarn comprising two sequentially formed loops that have the support strand attached intermediate the loops. For instance, two sequential loops are formed as the yarn is wrapped one revolution around a loop forming device such as the fork discussed below.

The pile yarn used to make the loop pile article of Fig. 6 may be a staple yarn or a ply twisted yarn or an entangled yarn or a continuous filament twisted yarn. If a twisted yarn is used that is twisted with several turns per inch, the yarn in the two legs of a single loop may ply together and reduce the twist energy in the yarn. Such a "plied loop" structure would look like Fig. 8 where the tufts 326 and 328 would appear as cut pile tufts, but with a small loop, such as 330, at the top of the tuft instead of a cut end.

Fig. 4 shows a method to make carpet using the tuftstring of the invention. A drum 78 is set up for rotation with a backing material 80 attached, for instance, by clamping the ends 82 and 84 of the backing in a slot 86 in the drum. The surface 87 of the backing facing outward would be coated with an adhesive coating, such as a thermoplastic adhesive. A block 88 is set to traverse along the rotational axis of the drum and carry a tuftstring guide 90 and a heating means 92 to locally soften the thermoplastic adhesive just before or coincident with contact with the tuftstring; such heating means may be a hot air jet, radiant heater, flame, or the like. The tuftstring 45 could be supplied from a reel 94 or directly from mandrel 30 of Fig. 1. As drum 80 is rotated clockwise, the tuftstring is pulled through guide 90, and heating means 92 locally heats the adhesive surface 87 on the backing 80. The tuftstring contacts the hot adhesive and is bonded to the backing. The block slowly traverses along the drum axis and lays down a spiral array of tuftstring to the backing surface, with adjacent runs of the spiral closely spaced so the just-applied tuftstring lies close to the previously-applied tuftstring in the array to define a pile surface structure. After the tuftstring has been traversed the length of the drum axis, the winding is stopped, and the assembly of tuftstring and backing is cut along the drum axis, such as at line 96 where the two backing ends come together at slot 86. In this embodiment shown, only the tuftstring need be cut at 96 and the backing ends released to remove the assembly. The assembly can then be removed from the drum and laid flat to form a pile surface structure or carpet. The carpet product made by this method has the feature that the adjacent rows of tuftstring come from different elongated portions of the same tuftstring which eliminates yarn lot variations within the carpet. For instance, a carpet having about 1kg/m² (3.3 oz/ft²) of yarn can be produced by first making a tuftstring from 2585 dtex (2350 denier), two strand, ply twisted yarn wrapped along the strand at 6 wraps/cm (15 wraps/inch) and 1.6 cm (5/8 inch) tuft length, and then mounting the tuftstring on the backing at a pitch of 2 tuftstrings/cm (5 tuftstrings/inch). Very little yarn is wasted since most of the yarn appears above the strand. For instance, with a 1.4 mm (0.055 inch) wide strand, the length of "wasted" yarn is only that which is wrapped around the strand, which for this example is about 1.59 mm (1/16 inch) out of a bundle length of 3.33 cm (21/16 inch), or about 4.7%. This makes more efficient use of the yarn compared to a conventional tufted carpet that for this case would have about 7.4% of the yarn below the backing.

Other means of making a tuftstring carpet structure are possible. For instance, a thermoplastic backing may be provided and the tuftstring attached using an ultrasonic bonding process. A plurality of groups of tuftstrings can be spirally wound on a drum simultaneously and arranged to come together laterally and circumferentially to complete the carpet in only a few revolutions of the drum. Alternatively, a complete carpet wide array of tuftstrings can be arranged to be attached to a continuous backing substrate as a warp to make a continuous length of carpet. A plurality of single ultrasonic horns can be used to bond a plurality of tuftstrings at a time to the backing either from the top side of the backing or from the back side of the backing. Such systems for making tuftstring carpets are described in US-A-5 804 008.

The backing substrate useful in the ultrasonic process is preferably a composite fabric of nonwoven nylon and fiberglass scrim as described in US-A-5 470 648. Preferably, the composite fabric is a moisture stable backing substrate. The support strand is preferably a structure comprising a core of a multifilament bundle of fiberglass coated with a sheath of nylon surrounding the core to provide a moisture-stable, structural adhesive strand as described in US-A-5 470 656.

The tuftstring carpet structure is preferably a moisture stable carpet structure as described in WO-A-96/06685, entitled Moisture Stable Tuftstring Carpet. The multifilament yarns used as the tuft yarns, or face yarns, may be manufactured by various methods known in the art. These yarns preferably contain filaments (fibers) prepared from synthetic thermoplastic polymers such as polyamides, polyesters, polyolefins, and acrylonitriles, and copolymers or blends thereof. Natural fibers, such as wool, may also be used. In a preferred embodiment, the tuft yarns are solution-dyed nylon yarns where the pigments or dyes are incorporated into the polymer melt or solution prior to extruding the blend through the spinneret. In a carpet context, these may also be referred to as pre-dyed nylon yarns since the color is put in the yarn before the carpet is tufted or otherwise formed.

The feature of frangible tuft strength of the tuftstring of the invention, as already discussed, may be useful for producing a "failsafe" carpet structure where the bond of the bundle to the strand can be tailored so that the pullout strength of a single tuft is less than the strength of a bundle of filaments before bonding. This allows the tuft pullout force to be adjusted so the tuft fails before the tuftstring structure pulls away from the carpet backing. At the low end, the tuft pullout force should exceed the normal requirements for carpet usage established by HUD (Housing and Urban Development product standards for carpet) and ASTM (American Society for Testing and Materials). It is also desirable that the pullout strength of a single tuft is less than the bond strength for the yarn bundle so the bundle does not separate from the strand thereby removing two tufts from the carpet. This is a unique feature that allows: 1) the tufts to withstand normal wear and tear, and 2) minimizes the damage caused by unusual forces pulling on the tufts. In conventional cut pile carpets made on a tufting machine, excess force on a single tuft causes a bundle, which includes two tufts, to pullout. With the frangible tuft feature of the invention, excess force on a single tuft may only cause that one tuft to pullout, thereby minimizing the damage to the carpet. In pile surface structures where this feature is not desirable, the bond can be tailored using the process of the invention so the tuft strength is increased to equal or exceed the bundle bond strength, but still be less than the strength of the bundle filaments before bonding. To summarize:$$\text{TUFT STRENGTH < YARN STRENGTH prefer: MIN PULLOUT < TUFT STRENGTH < BOND STRENGTH}$$

The yarn used in the elongated pile article may be a multifilament strand where the filaments are "connected" to one another. The filaments may be twisted at a level of at least about 0.4 turn/cm (1 turn/inch) to provide filament crossovers that enhance bonding (especially ultrasonic bonding), or the filaments may be entangled to provide crossovers. The yarn may comprise two or more strands of multifilaments that are ply-twisted together. The ply-twisting may be a "true" S or Z strand and ply twist or a reverse twist where the S and Z strand and ply twist alternate and there is a bond in the ply and strand twist reversal. Preferably the reverse twisted yarn has a bond in the plied yarn before reversing the twist as described in US-A-5 012 636. The yarn is preferably made from a thermoplastic polymer having the same composition as the strand so the yarn and strand can be bonded without the use of adhesives. The yarn is preferably made from crimped, bulky, heat-treated filaments commonly used as carpet yarns. The filaments of the yarn may have a variety of cross-sections which may be hollow and contain antistatic agents or the like. The yarn may have a finish applied that aids in ultrasonic bonding. The yarn is preferably a nylon polymer. The yarn may be a poly (aryletherketone) or a polyaramid or meta-aramid that is bondable with solvents, ultrasonics, or heat.

The strand useful in the elongated pile article may have a variety of cross-sectional shapes, such as square, rectangular, elliptical, oblong, round, triangular, multi-lobal, flat ribbon-like, etc. The strand must be bondable to the yarn and have sufficient elongational stability so the bonds are not over-stressed due to stretching of the strand. The strand must provide sufficient stability to the article that it can be handled for its intended use, such as attachment to a backing substrate. The strand may be a monofilament, a composite structure, a sheath/core structure, a reinforced structure, or a twisted multifilament structure. The strand is preferably made from a thermoplastic polymer having the same composition as the attached yarn so the yarn and strand can be bonded without use of adhesives. The strand is preferably a polymer having a molecular structure oriented in the elongated direction, and having a low dimensional change in the direction of orientation due to moisture gain or loss or modest temperature changes. The support strand is preferably a nylon polymer, such as Hyten® made by E. I. du Pont de Nemours and Company.

The aspect ratio (height/width) of the strand should be less than 1 so the tuftstring is stable and will not tend to tip over when mounted in a carpet and subjected to heavy loading due to furniture or high heeled shoes. Also, in the ultrasonic bonding process, a thick strand may absorb more energy than a thin strand so the ultrasonic process is less efficient. The thickness of the strand should not be so thin, however, that it becomes difficult to handle in subsequent processing steps needed to make a carpet. An aspect ratio of between .1 and 1.0 should work well for a strand used in the invention. A 1.42 mm (56 mils) wide strand that is 0.475 mm (19 mils) thick, giving an aspect ratio of 0.34, worked well assembled in a carpet sample made with the tuftstring of the invention.

Fig. 7 shows one means for making the loop pile tuftstring of Fig. 6. This apparatus is a variation of the apparatus of Fig. 1; like reference numerals are used where appropriate. One difference is that there is a fork 304 with a shaft 306 that is supported by a rotating bearing 308 that is attached to hollow guide conduit 26; the rotary bearing also restrains the fork against axial movement. The fork 304 has prongs 310 and 312 that extend on either side of mandrel 30' and provide supports for the yarn 20 that is wound onto the fork as loops 313 when conduit 26 rotates and feeds yarn from the conduit at 28. A support strand 32 is fed into the mandrel 30' at the far end of the mandrel and is guided through passage 36 and exits at 38. The strand 32 is guided to the outside of the mandrel and along ridge 40. The prongs 310 and 312 are close to the mandrel 30' and contact moving belts 314 and 316, respectively, that are guided around pulleys, such as pulleys 318 and 320 that are rotatably supported by frame 322 that may be attached to mandrel 30' or attached to an external support (not shown). Contact of the prongs with the belts acts to prevent rotation of fork 304, or fork 304 could be magnetically coupled to rotary support 27 to resist rotation; bent conduit 26 would pass through the magnetic field as it rotates without disturbing the magnetic coupling of the fork. Buildup of the yarn on the forks urges the yarn toward the belts 314 and 316 that move to assist the travel of the loops of yarn along the fork toward the mandrel. The prongs of the fork could also converge slightly to assist the initial movement of the yarn loops along the fork. Alternatively, the prongs of the fork could be parallel to one another and the individual prongs could be tapered from a first diameter where the yarn is wrapped on to a smaller second diameter where the yarn leaves the prongs. The yarn should also be wound under some tension to cause contraction of the yarn on the converged or tapered prongs and assist this initial movement along the prongs. As the loops 313 encounter the mandrel, they also contact the moving strand 32 that assists in moving the loops along the mandrel and under ultrasonic horn 42. The mandrel 30' has a ramped surface 326 that guides the support strand 32 onto a grooved surface on ridge 40 and into contact with the yarn. Preferably, the horn 42 is positioned along ridge 40 so the leading edge 42a of the horn is over the location where the ramped surface 326 meets the ridge 40. This bonds the yarn to the strand as soon as possible after they come together so the strand can assist in positively propelling the yarn. The horn bonds the loops of pile yarn to the surface of the strand 32 at about the midpoint of the loops to provide two upstanding loop tufts of equal length, one on each side of the strand. After the loops pass the horn 42, the loop tufts slide off the ends of the fork prongs, such as end 324, and the tuftstring can be removed from the mandrel 30'.

It is also possible to form a pair of loops where the loops are offset relative to the support strand 32 so the strand is bonded offset from the midpoint of the loops to create a special effect loop pile tuftstring. In this case, referring to Fig. 9, loop 300' on the right side of the strand would, for instance, be shorter by distance 328 (and, therefore, at a lower elevation) than loop 302' on the left side of the strand 32. When this type tuftstring is attached to a backing side-by-side with like tuftstrings in a carpet, the overall effect is similar to a cordurory fabric or sisal carpet style; there are alternating high and low rows of loop pile tufts. Such a hi-lo loop pile tuftstring structure can be made by shifting the rotary support 27 slightly off alignment with the ridge 40 on mandrel 30' in the direction of arrow 330. Since the prongs of the fork are ultimately attached to support 27 (through shaft 306, bearing 308, and conduit 26), this will move the prongs off alignment as well so that now one loop coming off the prongs will be longer that the other of the pair relative to the ridge that guides support strand 32 and the yarn under the bonding horn 42. Belts 314 and 316 may also have to be shifted as well to stay in good contact with the yarn on the prongs.

Means other than belts 314 and 316 may be used to assist movement of the yarn along the fork prongs. The above-mentioned yarn tension and convergence of the prongs may be sufficient means for some yarns and operating conditions. Other such means may be the incorporation of screw elements for the prongs where the screws are rotated by gearing to the shaft 306 and the rotating bearing 308. Still other means may be rotating brushes that gently engage the wrapped yarn on the prongs, or belts mounted within the mandrel that engage the wrapped yarn at the space between the prongs and the mandrel ridge.

Although the loop pile tuftstring invention has been described as it is made on an automated device such as the device of Fig. 7, it is contemplated that the invention can also be made by manual means or any other suitable means. For instance, the yarn can be wrapped by hand around a pair of parallel rods and laid across a ridge (edge) on a thin rectangular mandrel having a support strand taped along the ridge (similar to Fig. 18 in US-A-5 472 762). The rods would be placed on the sides of the mandrel, and the yarn would be bent over the ridge. An ultrasonic horn can be passed along the yarn where it is bent over the strand to bond the yarn to the strand. The rods can then be removed, and the loop pile tuftstring separated from the mandrel.

The strand is shown in the preferred position which is on the inside of the "U" shape, but the strand and bundle can also be attached with the strand on the outside of the "U" shape similarly to the cut pile article shown in Fig. 3A. To produce the loop pile article with the strand on the outside of the "U" shaped bundle, strand 32 in Fig. 7 would be a carrier strand, not bonded to the yarn, and a support strand, such as that shown in phantom at 32a, would be provided and bonded to the yarn as discussed in US-A-5 472 762 in reference to this alternate embodiment of Fig. 1 for a cut tuftstring.

The method just described using a fork for making a loop pile tuftstring can also be used to make a cut pile or a cut and loop pile tuftstring when means are provided for cutting the pile yarn loops, such as while they are still being transported along the prongs. If all of the loops are cut, a cut pile tuftstring results; if only some of the loops are cut, a cut and loop pile tuftstring results. One means for cutting would be to add an angled razor blade to the end of the prong after pulley 320, so as each loop is transported along the prong and over the blade, it will be cut by the blade. Alternatively, a slot could be provided in the prong or the mandrel opposite a rotary cutter similar to the slot 47 in the anvil 30 opposite cutter 44 in Fig. 1. The cutter could be moved in or out of the slot to alternately cut and not cut the loops. The cut could be in the middle of the loop or not for special pile height variations in the cut pile.

There are other styling variations possible using the paired loop process and apparatus of the invention. Variations in the yarn fed to the process can produce some interesting tuftstring carpet styles. Since the yarn is not cut as in a cut pile tuftstring, the feed yarn does not need to be consolidated to insure cohesive bundles of yarn remain after cutting for good tuft definition. For loop pile tuftstring, yarn can be used which has only been loosely entangled for good handling in stripping off a package and for guiding without snagging. For instance, a single entangled multifilament yarn strand with a very low twist level produces a bulky textured look in a tuftstring loop pile carpet structure, particularly if the yarn is a heather type yarn with variegated color pattern along its length. A further variation can be obtained if multiple yarn strands are fed to the wrapping conduit where at least one of the strands has a different appearance than the rest. The different appearance may be a different color, lustre, twist level, entanglement, space dye, heather, a ply twist versus no ply twist, etc. For instance, each strand may be a different color of solution-dyed yarn, or one out of five strands may be a different color of solution-dyed yarn. As the multiple yarn strands are wrapped, the wrapping process introduces a low level of twist to the group of multiple strands so periodic hiding of one color and then a different color occurs in the paired loops of yarn to obtain a look related to a heather or space-dyed yarn. This can be achieved without going through the additional steps preparing the feed yarn required for a heather or space-dyed yarn. This look also results in distinct color flashes that cannot be achieved with the heather or space-dyed feed yarns. Other variations can be contemplated by those practicing the invention. Another style can be achieved when using an alternate twist plied yarn as the feed yarn to the paired loop process. In this case, a different look is noticeable in the loops depending on whether the loops contain S-ply or Z-ply yarn. Where the yarn contains repeating segments of about 5 feet of S-ply and 5 feet of Z-ply, the loop pile tuftstring has about 3 inches of S-ply loops followed by about 3 inches of Z-ply loops. Where these are laid side-by-side to make a loop pile tuftstring carpet, a moire-type pattern can be seen by the eye where the S-ply loops periodically align with adjacent S-ply loops and the Z-ply loops periodically align with adjacent Z-ply loops.