Stringer Foundation For Slide Fastener

Abstract

A stringer foundation for a slide fastener has a pair of parallel tapes which have been simultaneously formed on a warp-knitting machine with a connecting filament joining their confronting edges. Each tape is formed by a plurality of warp chains laterally interconnected by laid-in weft filaments which span at least three of the wales formed by the chains. The connecting filament can be tensioned tighter than either the warp or weft filaments to form openings adjacent the edge wale. The connecting filament is adapted to be removed after mounting of the coupling elements.

Description

1. FIELD OF THE INVENTION

The preset invention relates to a stringer foundation for a slide fastener.

2. BACKGROUND OF THE INVENTION

Such a foundation is usually made of tapes woven separately on a single loom and then paired prior to attachment of the coupling elements. Since, as the loom operates, the various tensions inevitably change, the tapes always have different characteristics--elasticity, thickness, width, rigidity--throughout their length. Thus, in the finished stringer confronting sections of tape are often different, resulting in a fastener whose tolerances are low and which is difficult to attach to a garment.

It is further quite an expensive process to weave a thin band for such a stringer foundation, while subdividing a uniform wide band is not possible since the support tapes must be neatly selvedged.

In the commonly assigned co-pending application Ser. No. 52,377 filed 2 July 1970 by Alfons Frohlich and Karl Rohn and entitled "METHOD OF AND APPARATUS FOR MAKING SLIDE-FASTENER STRINGERS" now U.S. Pat. No. 3,633,528 a method is disclosed wherein two coils are fed to a sewing apparatus in an interleaved condition, are separated upstream of the sewing station, and are interleaved together again just downstream of this sewing station, i.e., after being sewn onto respective support tapes.

All of these steps are carried out simultaneously and continuously. In such a manner, the spacing between adjacent coil turns is carefully maintained the same since these coils are left interleaved up to the last possible instant before sewing, so that the finished slide-fastener assembly will not buckle or bow. At the same time the full turn is exposed under the sewing needle so that the sewing operation can be carried out at high speed, for high productivity. Immediately after sewing, the two coils are interleaved again to form a finished slide-fastener stringer.

The two coils, according to another feature of that application, can be separated and then fed through a series of guides which keep the interturn spacing the same by tensioning the two coils to the same extent and/or by making them both travel along paths of identical length.

3. OBJECTS OF THE INVENTION

An object of the present invention is an improved slide-fastener stringer foundation.

Another object is to advance the principles set forth in the above-cited patent application.

Yet another object is to provide a stringer foundation to which it is easy to attach a pair of coupling elements, while the tapes are identical in their various characteristics on both sides of these coupling elements.

4. SUMMARY OF THE INVENTION

The above objects are obtained, according to the present invention, by a stringer foundation for a slide fastener comprising a pair of selvedged warp-knit parallel support tapes whose confronting edges are joined together by a removable connecting filament passing back and forth between them.

The tapes are identical in neighboring sections, on each side of the coupling elements, since they are knit simultaneously and are held together by the removable connecting filament. Feeding of the two joined tapes to the sewing station, where they are separated immediately before or after the attachment of the coupling elements, becomes an extremely simple operation since only a single tape, in effect, need be guided.

In accordance with other features of the present invention the edges of the tapes are reinforced, either by doubling or tripling the yarn or by using bulk yarn, to make the tapes as thick at these edges as they are in the center, since some of the laid-in weft filaments much be left out adjacent the tape edges to make a neat selvedge. It is also possible to set partially one of the guide bars of the circular, flat-bed or Raschel knitting machine to leave out weft filaments in the center so that the finished tapes are of regular cross-sectional thickness.

The weft filaments, according to another feature of this invention, are laid in and have a weft reach (the number of wales spanned) of at least three, and preferably four, wales while the connecting filaments have a reach of two or four wales.

Another feature of the invention is that the connecting filament is tensioned tighter than the other filaments so that the edge wales of each tape at their confronting edges are compressed and pulled from the rest of the tapes to enlarge the adjacent valley and form a series of openings through the tapes. These openings serve to accommodate the stitching that holds the coupling elements to the tapes so that it need not pass through and damage other filaments, or the coupling heads of the coils can be simply forced therethrough to anchor them. Cutting of the connecting filament after attachment of the coupling elements causes these openings to shrink and the tapes to fold back.

According to a further feature of this invention, the connecting filament has a lower melting temperature than the other tape-forming filaments so that a subsequent thermofixing process melts it. It can also be made of some material which is dissolvable in a bath.

In our concurrently filed and commonly assigned application Ser. No. 82,327 there is disclosed a slide-fastener stringer comprising a pair of elongated warp-knit support tapes having confronting longitudinal edges, each tape being constituted of a plurality of transversely offset longitudinally extending warp chains and laid-in weft filaments transversely connecting the chains to form a warp-knit foundation, and respective elongated continuous coupling elements interconnectable upon movement of a slider therealong and lying along the confronting edges and secured thereto.

In such a stringer the weft filament is laid in with a 4-4/0-0 pattern and the warp filament is chained in a 0-1/1-0 pattern, or a 2-0/0-2 pattern, or a pair of such warp filaments are provided, one chained in a 0-1/1-0 pattern and the other in a 2-0/0-2 pattern.

The tapes of this stringer are formed with stitching holes for attachment of the coupling elements and its weft filaments are voluminous textured (bulk) yarn.

That application also discloses a method of making a slide-fastener stringer comprising the steps of forming a plurality of transversely offset longitudinally extending warp chains, laying into these chains a plurality of weft filaments to form a pair of warp-knit foundation tapes, securing an elongated coupling element to the confronting edges of the tapes, and thermally fixing the tapes.

Our commonly filed and assigned application Ser. No. 82,326 discloses a slide-fastener stringer comprising a pair of interengageable coupling elements each having a multiplicity of turns, a pair of warp-knit support tapes having wale-forming warp filaments and course-forming weft filaments, and a succession of stitches passing between the turns and through the tapes and securing the elements to the confronting edges of the tapes, the stitches having a stitch length greater than the course width. These stitches pass through the tapes between the wales, and the stitch length is an integral multiple of the course width, e.g., equal to twice the course width. The weft filaments are laid in a 4-4/0-0 pattern and at least some warp filaments are chained in a 0-1/1-0 pattern while other warp filaments are chained in a 2-0/0-2 pattern. The warp and weft filaments are of greater bulk adjacent the edges than remote therefrom. The wales are on one face of the tapes, the other face being smooth and engaging the coupling elements.

Our commonly filed and assigned application Ser. No. 82,325, now U.S. Pat. No. 3,685,474 discloses a method of making a slide-fastener stringer comprising the steps of simultaneously forming a pair of parallel fabric tapes and joining same together at their confronting edges by at least one connecting filament, thereafter simultaneously attaching one of a pair of interengageable coupling elements to each of the confronting edges, and breaking the connecting filament to separate the tapes. These tapes are warp knit by forming a plurality of longitudinally extending wale-forming warp chains from a plurality of warp filaments and laying into the chains a plurality of course-forming weft filaments. The weft filaments are spanned across at least three wales and the tapes are also knit with second warp filaments chained in opposition to the first warp filaments while at least one of the filaments which comes to the edge of the tapes is reinforced.

That application also describes a method as above with the additional step of tensioning the connecting filaments more tightly than the warp and weft filaments to form a succession of openings in the tapes between the wales adjacent the confronting edges, whereby breaking the connecting filament separates the tapes and substantially closes the openings. The elements are attached by sewing with stitches passing through the openings, or the elements are attached to the tapes by passing their coupling heads through the openings. The connecting filament may be spanned over only two courses so that the openings are formed adjacent the edge wales of the tapes. Four such tapes can be knit interconnected by three such connecting filaments, the method then further comprising the step of cutting the central filament prior to attachment of two pairs of interengageable coupling elements to the two joined pairs of tapes thus formed.

Our concurrently filed and commonly assigned patent application Ser. No. 82,324 discloses a slide-fastener stringer comprising a pair of inter-engageable coupling elements, a pair of parallel warp-knit support tapes each having longitudinally extending parallel wales including at least one wale defining a band along the edge of the tape separated from the rest of the wales by a valley, and respective rows of stitching each engaging over one of the elements and passing through the respective tape only in its valley for securing the elements to the tapes. In such a stringer the edge band is formed by a single wale constituted largely from a reinforced warp filament, or it can be formed by a pair of wales. The stringer of that application can have a connecting filament extending between the edge bands of the pair of tapes and tensioned to broaden the valleys, thereby facilitating stitching of the elements to the tapes. The tapes each have a smooth face, with the elements attached to the smooth faces.

5. DESCRIPTION OF THE DRAWINGS

The above and other objects, features, and advantages will become apparent from the following description, reference being made to the drawing, in which:

FIGS. 1, 2 and 3 show the combined notation for three embodiments of the knit according to the present invention;

FIG. 4A is a diagram showing the guide-bar movement for producing the knits of FIGS. 1 and 3;

FIG. 4B is a diagram showing the threading of a knitting-machine guides for producing the knits of FIG. 1;

FIGS. 5 and 6 show the combined notation of fourth and fifth embodiments of the knit according to the present invention;

FIG. 7 is a cross section through a slide-fastener stringer according to the present invention; and

FIG. 8 is a sixth embodiment of the knit according to the present invention .

6. SPECIFIC DESCRIPTION

To fully appreciate the structure of the knits, it is necessary to understand the notation of FIGS. 1 - 6 and 8.

FIGS. 1, 2, 3, 5, and 6 and 8 represent standard tricot point paper notation wherein each dot stands for a needle. The vertical rows of dots symbolize the wales and the horizontal rows symbolize the courses. The lines passing around the dots represent the paths of the guides during knitting and, therefore, the pattern of the yarns carried by these guides. FIG. 4A shows the paths of the individual guides, and FIG. 4B shows which of the guides are threaded for each row of needles.

Thus, for the knits of interest here two types will be seen. The guide bar can move from one space to another during each knitting cycle, i.e., the formation of each course, and then move back during the next raising and lowering of the needles. For example, the figure notation for a guide which moves from space 0 to space 1 during one knitting cycle then back from space 1 to space 0 during the next cycle is 0-1/1-0, with the slash mark (/) separating the two cycles.

The other type of guide movement of interest is that of laying-in. In this case the guides do not move in front of the needles (overlap) but merely shog back and forth behind the needle hooks between cycles. The notation here is similar, so that 4-4/0-0 is the figure notation for a guide which, as the needles move up and down for one course, stands in space 4, and then moves to space 0 where it remains as the next course is knit. In other words, the first two digits signify the two positions between which the guide reciprocates during one knitting cycle and the second two digits indicate the end positions for the next cycle. After every two cycles the movements are repeated. Since for laying-in the guides do not move during the knitting cycles, but between them, on each side of the slash mark both numbers are the same.

For a more detailed discussion of the above forms of notation reference can be made to the book Advanced Knitting Principles edited by Charles Reichman (National Knitted Outerwear Association: 1964), chapters 26 and 30.

As seen in FIG. 1, a slide-fastener stringer comprises a fabric 1 constituted by a pair of tapes 7 and 8 each adapted to carry a nylon coupling coil 2 (see FIG. 7). Each tape 7, 8 consists of warp yarns 4 and 5 and weft yarns 6, and the tapes are temporarily linked at their confronting edges by a connecting filament 9.

The short-reach warp yarns 4, as shown in FIG. 4A, are chained by the fourth or front guide bar in a 0-1/1-0 pattern, whereas the long-reach warp yarns 5 are chained by one of the middle guide bars in opposition thereto with a 2-0/0-2 pattern. The connecting filaments 9 are breakable and are laid in with a 2-2/0-0 pattern by one of the back guide bars whereas the weft filaments 6 are laid in parallel thereto with a 4-4/0-0 pattern. The finished tapes, thus, have wales 3 separated by valleys or troughs 1 and courses 15. FIG. 4B shows that the frontmost guide bar is fully set, while the other bars are not, so that two tapes will be selvedged and separate when produced on the same knitting machine as is the case here. The band 1 thus can be subdivided into a pair of neat selvedged tapes 7 and 8, while the fabric characteristics will automatically be identical all through the same course 16, that is, on both sides of the tape's center.

FIG. 1 shows how bulk filaments 6' are used instead of the filaments 6 where these run to the edge of the tapes. Instead of simply using a bulky or textured yarn, it is also possible to double-thread the respective guide bar. In this manner the tapes are of regular thickness across their entire width so that handling of them later presents little difficulty.

In FIG. 2, a connecting filament 9' is shown which is chained in a 2-0/0-2 pattern, rather than simply being laid in. Such a structure makes for a very stable band 1, which here is shown to consist of more than two tapes 7 and 8. Reinforced warp filaments 4' and 5' are also used here where these come to the tape edge.

FIG. 3 shows a pair of tapes 7 and 8 wherein only reinforced warp filaments 4' and weft filaments 6' are bulkier than the other filaments, in order that the finished tapes have regular cross-sectional thickness. In addition, the connecting filament 9" is laid in with a 4-4/0-0 pattern.

In FIG. 5 all filaments which come to the edge of the tapes 7 and 8 are reinforced for greatest strength, much as in FIG. 2, except that the connecting filament is here laid in with a 2-2/0-0 pattern.

A single tape 7 is shown in FIG. 6 which in its central region does not have a separate weft filament 6 for each warp filament 4 or 5. In this manner, the central thickness of the tape 7 is reduced. This effect is achieved by only half setting each of the guides of the first guide bar toward the center of each tape.

FIG. 7 shows how the tapes of FIG. 6 are connected to Nylon coil-type coupling elements 2. The valley 11' directly adjacent the edge of the tapes 7 and 8 receives stitching 12. The edge wale 3 is thickened, as shown at 10, on account of the reinforced filaments used in its formation. The edge valley 11' is of relatively large width since the connecting filament 9 for these tapes 7 and 8 is tensioned more tightly than the other filaments and therefore pulls the two edge wales 10 away from the rest of their tapes.

In FIG. 8 there are shown a pair of tapes 7 and 8 each of which is formed in two portions 13 and 14, separated by a space formed by leaving out one of the long-reach warps 5 and the short-reach warp 4 one wale in from this edge. In this manner are formed openings 15 adapted to receive the coupling heads of a slide-fastener coupling element 2 which is therefore fastened to the tape without stitching. The connecting filament 9 is also tensioned tightly in this case so that, after it has been severed, the holes 15 close up somewhat around the elements.

The connecting filaments 9, 9' and 9" are made of an easily dissolvable material such as polyvinyl alcohol, so that their removal can be readily carried out in a bath of water. It is also possible to provide connecting filaments which have a melting temperature much lower than that of the other filaments and the coupling elements so that after mounting of the coupling elements the connecting filament can be melted out by a heat-treating or thermofixing process.

Claims

We claim:

1. A textile web comprising two unitarily and integrally knit longitudinally extending slide-fastener support tapes each consisting of a plurality of longitudinally extending wales formed by at least two warp threads, a laid-in weft thread, and at least one connecting filament extending back and forth between the proximal wales of said tapes and destructible to separate said tapes, at least one of said threads being of greater thickness than others of said threads and said filament for reinforcing the confronting edges of said tapes along said proximal wales, whereby said confronting edges are thicker than the remainder of said tapes, said connecting filament being tensioned tighter than said threads to produce a respective valley adjacent each proximal wale which is substantially broader than the valleys separating their remaining wales.

2. The web defined in claim 1 wherein said laid-in thread extends across at least three wales.

3. The web defined in claim 2 wherein said warp threads are laid in a 1-0/0-1 pattern.

4. The web defined in claim 3 wherein said connecting filament is laid in a 4-4/0-0 pattern.

5. The web defined in claim 3 wherein said connecting filament follows a 2-0/0-2 pattern.