Slide fastener

[57] ABSTRACT

Each half of a slide fastener having two halves adapted to be sewn onto a carrier ribbon has a plastic thread formed into a series of helical loops defining convolution portions. Each convolution portion is flattened only in a limited region of each loop that overlaps a loop in the other half of the slide fastener and to a width substantially twice the diameter of the thread. These flattened regions form coupling surfaces which serve to inter-engage with the coupling surfaces formed in the other half of the slide fastener. The flattened regions are sharply kinked and the convolution portions adjacent the flattened regions only are disposed in superposed relation contacting each other and merged opposite to the flattened surfaces into oppositely directed, exposed, smooth return bend portions.

Claims, 9 Drawing Figures

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PATENTEDJUN 61972

3,667,089

SHEET 1 OF 3

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Attorney

PATENTEDJUN 61972

SHEET 2 OF 3 &lt;·

3,667,089

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BY

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Attorney

PATENTEDJUN 61972

3,667,089

SHEET 3 OF 3

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7*9- 5

BY

Hans Porepp INVENTOR.

Ού»¹Attorney

3,667,089

SLIDE FASTENER

This application is a division of application Ser. No. 590,080 filed Oct. 27 1966 (now U.S. Pat. No. 3,461,486 issued Aug. 19, 1969.).

BACKGROUND OF THE INVENTION

The invention relates to a slide fastener chain for a slide fastener the two halves of which may be sewed to a support tape or stringer, each consisting of a series of coupling links made of a plastic, or synthetic thread laid in the configuration of a deformed helical spring. The convolution portions of the helical springs extend from the coupling surfaces disposed in superposed relation in planes perpendicular to the longitudinal direction of the slide fastener.

Slide fasteners with series of coupling links made of a thread of plastic material in the form of a deformed helical spring are known, in which the coupling surfaces of one series of links, together with the convolution portions merge therewith, form loops for the engagement of the coupling surfaces of the other series of links. This the winding portions merging with the higher loop are disposed in superposed relation in planes perpendicular to the longitudinal direction of the slide fastener, while the convolution portions having the full pitch and being disposed opposite to the coupling surfaces extend tile-like, i.e., overlapping one over the other.

SUMMARY OF THE INVENTION

The present object of the invention is to provide a slide fastener, or a series of coupling links, in which the entire width of the series of coupling links is kept evenly as flat as possible and having a height which at no point exceeds the double thickness of the thread, thus assuring an extremely rigid coupling engagement;

Accordingly, the invention resides in that, in a slide fastener as described above, the convolution portions extending from the coupling surfaces initially lie snugly together one above the other, then merge opposite to the coupling surfaces into opposed return bends, and that the coupling surfaces, together with the convolution portions extending therefrom and contacting each other, form ears disposed within the height of the two contacting convolution portions and serving as engagement means for the coupling surfaces of the second series of coupling links of the slide fastener. Thus, the height of the series of coupling links of the slide fastener fixed to a carrier ribbon in no case exceeds the double thickness of the plastic material thread used for its manufacture, and, since the coupling surfaces formed by coining flat ears and sharply kinking the same are disposed within the zone of the height of the double thickness of thread, the coupling surfaces of the other series of coupling links engage with full surface contact behind the ears, whereby the safety against tearing-open is improved substantially.

The slide fastener according to the present invention can be manufactured in a particularly simple manner wherein, according to the method of the invention, the procedure is such that two threads of a synthetic material are guided in one plane while being deflected side-by-side in opposite directions by thread guides along a base and are, after complete overlapping of the overlapping thread portions, provided in staggered relation with coupling surfaces by coining, whereupon the threads are sharply kinked at the coupling surfaces engaging behind each other above the approaching thread extension, and are guided back in contacting engagement thereto, and wherein the two convolution portions of the two series of coupling links, which are coupled by the engaging coupling surfaces are shifted forwardly about one pitch of the helical coil and are stabilized in their positions by applying heat.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a top schematic view of the two series of coupling links of a slide fastener according to the invention in coupling engagement in an enlarged scale;

FIG. 2 a cross-sectional view along line II—II of FIG. 1 but to a larger scale than HG. 1;

HG. 3 a cross-sectional view corresponding to FIG. 2, but of a modified embodiment of the coupling links;

HG. 3a is a cross-sectional view taken generally along the line 3a—3aofHG. 3;

HG. 3b is a view of a convolution portion having a transversely serrated, longitudinal groove defined therein, but without a string arranged in the groove;

HG. 4 a partially cross-sectional view of the device for performing the present invention, showing the thread guides and a top view of the cylinder below the thread guides;

HG. 5 a cross-sectional view corresponding to HG. 4, in which the thread guides are in their extreme outward positions;

HG. 6 a top view of the thread guides with the advancing device; and

HG. 7 a side view, partly in section, of the complete device for making the coupled series of coupling links.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The two series of coupling links of a slide fastener consist each of a plastic thread I and 2 shaped to a deformed helical spring, wherein the convolution portions 5, 6 and 7, 8 of both series of coupling links extending outwardly from the coupling surfaces 3 and 4 are disposed in superposed relation snugly contacting each other, merging opposite to the coupling surfaces 3,4 into oppositely directed exposed return bends 9, 10. This shape of the convolution portions permits continuous manufacture, as will be explained later. The coined coupling surfaces 3 and 4, which are flattened widenings of the thread form with the convolution portions 5, 6 and 7, 8, by sharp kinks of the coupling surfaces, a loops disposed within the height of the two contacting convolution portions, into which loop the coupling surfaces of the other series of links engage. Thus the height of the slide fastener above the carrier ribbon does not exceed the double thickness of the thread. The projecting portions of the coupling surfaces formed by flattening of the thread completely engage in abutting relation in the loops, whereby an extremely secure connection, with perfect safety against tearing-open is achieved.

The pair of coupling elements or chains of the slide fastener are attached in the well known manner to respective support tapes or carrier ribbons, as by sewing. As shown in FIG. 2, a narrow cover ribbon 50 may be provided as ironing protection; or it is also possible, according to FIG. 3, to provide the outer side of the convolutions facing away from the carrier ribbon with a longitudinally extending groove or recess 13 in which a string 14, or the like, is placed and sewn together with the coupling elements to the carrier ribbon, thereby forming an ironing protection. By means of this groove 13, the string 14 and also the series of coupling links are prevented from shifting laterally. This security may yet be improved in that longitudinally and/or transversely extending serrations are provided in the groove 13, as shown in HG. 3a and HG. 3b. The production of the pair of series of coupling links of the slide fastener which are in inter-engaging relationship with each other, is as follows:

The threads 1 and 2 which can be of a well-known synthetic resin, are fed from a supply roll and run over thread tighteners or tension devices, (not shown,) traverse the bores 18 and 19 are located opposite the circumferential portions of the cylinder 15 at the outer sides of the beads 22, 23. The thread guides are then moved by a suitable drive (not shown) in a direction towards each other, while the plastic threads are pulled through the bores; the coining projections 20 and 21 urge the threads against the circumferential surface of the cylinder 15, as shown in FIG. 4. The thread guides 16 and 17 then move towards each other, so that the guide bores 18 and 19 pass each other, whereby the plastic threads 1 and 2 overlap each other on the base, or cylinder 15. At this moment, the thread guides 16 and 17 are pressed against the circumference of the cylinder 15 in the direction indicated by the arrow 24, for example by means of a cam drive 24a, as shown in HG. 7, and thereby produce deformations or widenings of the thread.

3,6

According to FIG. 7, thus forming the coupling surfaces. Subsequent to this coining operation, the thread guides 16 and 17 return to their initial positions, whereby the threads 1 and 2 are sharply kinked at the deformations 25 and 26 by the rounded bore edges disposed opposite the coining projections 20 and 21 and the under-surfaces 16α and 17α of the two thread guides. This causes the deformations of the two threads to inter-engage with each other, so that the threads 1 and 2 are flattened in direct contacting engagement during the forward movement. Thus, it is achieved that the two series of coupling links have a height which under no circumstances is higher than twice the thickness of a thread. This extreme position of the thread guide is shown in FIG. 5. It is to be noted that, during the forward movement of the thread guides, the coining projections 20 and 21 are urging the thread tightly against the circumference of the cylinder 15. Due to this pressure, and the provision of the serrated annular beads 22, 23, the longitudinally extending grooves or recesses 13 receiving the strings 14 are formed in the parts of the convolutions of the thread disposed below, as mentioned in connection with FIG. 3.

As soon as the two thread guides move back out of the position shown in FIG. 4 to the position shown in FIG. 5, a slide 27 is actuated. This slide is guided tangentially with respect to the circumference of the cylinder 15 between its circumference and the thread guides. This slide is, as shown in FIG. 6, stopped at the front side corresponding to the shifted position of the two superposed convolution portions of the two series of coupling links, and pushes the convoluted portions forwardly through a distance equal to one pitch spacing of the series of coupling links; the freely rotating cylinder 15 is similarly advanced, and the threads 1 and 2 are pulled through the guide bores 18 and 19, whereby the arcuate shape of the coupling links is achieved, as shown in FIG. 1. Upon renewed forward movement of the thread guides, the slide 27 moves backwardly a corresponding distance by means of the reciprocating slide movement, which is continuously, but with varying speed, regulated by a corresponding control, so as to achieve the arcuate shape of the individual coupling links. Then the several successive operations are repeated.

The slide 27 pushes the formed coupling links, which engage one another, in a directly connected channel 28 surrounding the cylinder 15 in parallel relation, and having a cross-sectional shape adapted to that of the series of coupling links interengaging each other. Within this channel 28 the coupling elements are subjected to a heat treatment in a wellknown manner, so as to remove the inner stresses caused by

57,089 the shaping of the coupling links and to stabilize them. Finally, the series of coupling links, which interengage each other, arrive at the outlet of the channel and are lifted from the cylinder by a wedge 29, and are then attached to carrier rib5 bons in a known manner. As mentioned above, the freely rotatably journalled cylinder 15 rotates at each advance of the slide 27 with the interengaged series of coupling links about one pitch spacing, so that the inter-engaged series of coupling links engage the cylinder 15 without friction, so that only the 10 friction on the outer channel walls must be overcome upon the passage through the channel 28.