The example to be described in most detail here relates to the manufacture of carpets. Traditionally, carpets are made by textile processes such as weaving or tufting. To obtain economies of scale, they are mass produced in lots on the order of ten to fifteen feet in width and one hundred feet or more in length. Large pieces are then cut from the lots, trimmed and shaped as necessary, and installed where desired.

A new method of constructing carpets, right at the point of installation, is suggested in U.S. Application Serial No. 08/017,162, filed February 22, 1993 and entitled "Method and Apparatus for Making a Pile Article and the Products Thereof," which is incorporated by reference. The application teaches a method for making tuft-strings which comprise continuous, elongated monofilament support strands and U-shaped tufts of yarn ultrasonically bonded to the support strands with the legs of the "U" straddling the support strands. The application suggests that many tuft-strings may be secured in place, to construct a carpet in situ, using hook-type fasteners resembling those described in Fischer, U.S. Patent No. 4,775,310. Fischer teaches a method and apparatus for making a molded hook product for use with hook and loop fasteners. The hook product is made by directing molten plastic resin between a forming roller and a co-acting, pressure applying roller. The forming roller is made up from an alternating stack of molding rings, which have

96/05961 PCMJS95/10649

- 2 - hook-shaped cavities extending inward from their peripheries, and spacer rings, which have no such cavities. The pressure roller forces the molten resin into the cavities to form hook-shaped engaging elements ("hooks") which extend from, and which are molded integrally with, a thin base member. The hooks are aligned in columns with the crook portions of the hooks - - the portions responsible for engagement with loops to effect hook and loop fastening — aligned in the machine direction.

Summary of the Invention In general, the invention features a hook fastener suitable for securing thereto a plurality of elongated elements in parallel, side-by-side fashion. The fastener is formed by the "cut-and-stretch" method wherein a resin preform with upstanding ribs — at least some of which have a hook-form profile — is extruded. The ribs are sliced transverse to the machine direction and the base of the preform is stretched to separate the ribs into discrete hook-form fastening elements. The fastening elements have stems and at least one retaining arm extending from the stem toward the next adjacent rib portion. The hook-form fastening elements are configured and disposed such that the elongated elements may be pushed into the spaces formed between adjacent rows of fastening elements and held therein, and such that the elongated elements are trapped by the retaining arms and prevented from being pulled out of the spaces.

Preferred embodiments can have the following features. The retaining arms can have curved upper surfaces which guide the elongated elements into the spaces. Tips of the retaining arms of transversely adjacent fastening elements can be spaced apart by a distance which is less than the width of the elongated elements. Preferably, the tips of the retaining arms are

spaced apart by a distance which is half the width of the elongated elements or less. The configuration is such that pulling the elongated elements in a direction normal to the base member and away from the spaces causes the elongated elements to engage the tips of the retaining arms and force the tips together. The ribs are sliced at an angle of from about 20° to about 90° relative to the machine direction, with 90° or 45° being preferred. Brief Description of the Drawings Fig. 1 is a diagrammatic perspective view of a tuft-string;

Fig. 2 is a diagrammatic perspective view of a hook fastener according to the invention.

Figs. 3 and 4 are diagrammatic perspective views showing the process by which the hook fastener of the present invention is made.

Fig. 5 is a diagrammatic, partial end view of a carpet made using the hook fastener of Fig. 2.

Figs. 6-10 are diagrammatic, partial end views showing the assembly of the carpet of Fig. 5.

Fig. 11 is a diagrammatic, partial end view showing the attempted removal of a tuft-string from the carpet of Fig. 5.

Fig. 12 is a diagrammatic, partial end view showing relative dimensions of the carpet of Fig. 5.

Figs. 13 and 14 are diagrammatic, partial side views showing the axial spacing of the fastening elements of the hook fastener of the invention.

Fig. 15 is a diagrammatic plan view of an alternative embodiment of the hook fastener of the invention.

Description of the Preferred Embodiments As shown in Fig. 1, which is excerpted from the above referenced U.S. Application Serial No. 08/017,162, a tuft-string 10 comprises a monofilament support strand

12 to which are bonded a multitude, e.g. six or seven per inch, of U-shaped yarn tufts 14 with legs 16, 18 straddling the monofilament support strand. The support strand and yarn tufts are typically high tenacity nylon 66. A multitude of such tuft-strings can be attached to a fastener member, as will be described in more detail below, to construct a carpet or other similar pile product.

As shown in Fig. 2, a fastener member 20 comprises a base 22 and a multitude of umbrella-shaped fastening elements 24 integrally molded with and extending from the base. Each fastening element has a stem 26 and a pair of retaining arms 28 extending out and down from the stem. The fastening elements are aligned in columns running the length of the fastener member such that the curved upper surfaces 30 of the retaining arms form troughs or channels 32 between adjacent columns.

As will be observed in Fig. 2, and as is described in greater detail below, the tips 34 of the retaining arms are quite close together. Furthermore, as will also be explained below, it is desirable to have the retaining arms oriented at an angle, e.g. perpendicular, to the lengthwise direction of the fastener member.

To obtain such spacing and orientation, the fastener member is produced by the method referred to in the art as "cut-and-stretch." In this method, as illustrated in Figs. 3 and 4, resin such as polyvinyl chloride is extruded through an appropriately shaped die to produce a sheet form 36 consisting of a base form 38 with rib-like fastening element forms 38 extending therefrom. The width of the sheet form is typically on the order of four to six inches or less, but is essentially continuous in the lengthwise or machine direction, indicated by arrow 40, i.e., the direction in which the sheet form is extruded. The fastening element

forms are sliced at an angle — typically 90° — to the machine direction and the base member is stretched in the machine direction to separate the fastening element forms into the individual, discrete fastening elements, as shown in Fig. 2.

Referring to Fig. 5, a pile product such as a carpet is constructed by pressing the support strands 12 of many individual tuft-strings 10 into the channels 32 between columns of fastening elements 24. As noted above, it is preferable to have the retaining arms oriented at an angle, e.g. perpendicular, to the lengthwise direction of the fastener member, such that the channels are oriented along the length of the fastener member. This is because the fastener member, although as long as desired, is just a few inches wide. For efficiency and neat appearance of the final carpet, it is preferable to use, e.g., ten or twelve fastener members of the appropriate length laid side by side with the channels and tuft-strings running along the length of the member. Laying on the order of forty or more fastener members side by side with the channels running across the length of the fastener member, in contrast, is more labor intensive and necessitates having the tuft- strings jog back and forth somewhat as they cross each successive fastener member. This can give the finished carpet an appearance which is not neat.

The insertion process is shown in detail in Figs. 6-10. As the monofilament support strand 12 of a tuft- string 10 is inserted into a channel 32, and the legs of the yarn tuft contact the upper surfaces 30 of the fastening elements (Fig. 6) , the legs of the yarn tuft are squeezed together and the retaining arms 28 begin to be pushed apart (Fig. 7) . Continued downward force causes the retaining arms to be pushed even further apart (Fig. 8) until the support strand bypasses the tips 34 of

the retaining arms (Fig. 9) . The retaining arms then flex back to their original positions, owing to the resilience of the resin from which the fastener member is made, and the support strand is thereby secured (Fig. 10) , with the yarn tufts extending upward between the retaining arms of columnwise adjacent fastening elements. As shown in Fig. 11, if an attempt is made to pull a yarn tuft out of the fastener member, the support strand engages the tips of the retaining arms and forces them together, thereby blocking travel of the support.

In this manner, adjacent fastening elements provide a one way valve-type action, permitting relatively easy insertion of the tuft-string but making removal relatively difficult. (If necessary for repair of the carpet, it is possible to pull the tuft-string out from between engaging elements by pulling on an end of the monofilament. Shearing the yarn tufts at a level close to the upper surfaces of the retaining arms facilitates removal.) With regard to dimensions, as shown in Fig. 12, a typical tuft-string has an oval support strand 12 of width W, e.g. 0.0316 inches, and thickness T, e.g. 0.013 inches. In order to obtain the one-way securing action described above, the tips of the retaining arms must be spaced apart by a distance which is less than the width W of the support strand. A distance of one-half W or less, e.g. 0.0135 inches, is presently preferred. The retaining arms curve downward, as described above, such that the tips are at a distance above the base member of about three times T. The tuft-string is held secure, however, despite the space between the support strand and the tips of the retaining arms, by entanglement of the tips in the fibers which make up the yarn tufts. The thickness of the fastening elements, which is set by the cutting step of the cut-and-stretch process, should be

small enough to ensure flexibility of the retaining arms and to permit good penetration of the retaining arms into the yarn tufts.

In terms of spacing between fastening elements within a given column, a bit more variation is allowable. The spacing between fastening elements within a given column is set by the amount by which the base form is stretched during the "cut-and-stretch" process; it may range from an amount on the order of twice the thickness t of the fastening elements, as shown in Fig. 13, to five times the thickness t, as shown in Fig. 14. The fastening elements should not be so close together that the yarn tufts can not fit between them and "bloom out," as that would leave the columns of fastening elements visible at the base of the carpet. On the other hand, the fastening elements should not be spaced so far apart that the tuft-strings are not held securely.

As shown in Fig. 15, the retaining arms of the fastening elements can be oriented at an angle other than 90° to the machine direction. This is achieved by slicing the fastening element forms, during the cutting step of the cut-and-stretch process, at the desired angle. In the embodiment shown in Fig. 15, that angle is about 45°. The benefit of having the retaining arms oriented at angles of less than 90° to the machine direction is that the tuft-strings can be redirected — such as within the border of a carpet which is a different color than the rest of the carpet — from running in the lengthwise direction to running in the widthwise direction, yet still be held secure by the overlying retaining arms.

It will be appreciated that the hook fastener of the present invention may be used to secure elongated elements other than tuft-strings. For example, it is contemplated that strands of brush bristles can be

secured in similar fashion. Furthermore, the hook fastener of the present invention may be used to install electrical wiring or bundles of fiber optics. Other embodiments are within the scope of the following claims.