US 3591914 A
Description (OCR text may contain errors)
United States Patent METHOD AND APPARATUS FOR MAKING FLUIDTIGHT SLIDE FASTENER 10 Claims, 8 Drawing Figs.
' US. Cl 29/408, 29/2075, 264/320 Int. Cl 829d 5/00, B2lf45/l8, B21d 53/54 Field 0! Search 29/408,
 References Cited UNITED STATES PATENTS 3,190,779 6/1965 Porepp 156/66 3,270,408 9/1966 Nealis... 264/320 X 3,430,329 3/1969 Ausnit 29/408 Primary Examiner-Thomas H. Eager Attorney-Karl F. Ross ABSTRACT: A method and apparatus for making a slide fastener whose halves consist of continuous filaments, of helicoidal or meandering configuration, by extrusion of a sealing material about the interlocked coupling elements so that they are almost completely imbedded in respective sealing strips of elastomeric material which meet in the plane of symmetry of the fastener and are provided with complementary elongated formations extending over the full length of each strip, these formations yieldably interlocking upon closure of the fastener and being also in mating engagement with a projection and recess, respectively, of an associated slider.
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BY Ow g '1 AttornBY METHOD AND APPARATUS FOR MAKING FLUIDTIGIIT SLIDE FASTENER This application is a division of my application Ser. No. 651,269 filed July I967, now U.S. Pat. No. 3,428,820 and also relates to a fluidtight slide fastener of the type disclosed in my'then-pending application Ser. No. 534,356 filed Mar. 1966 (now US. Pat. No. 3,389,441).
Slide fasteners are frequently used as closure means for garments or other articles (e.g. inflatable rafts, sleeping bags, tents) which are exposed to the weather, used underwater or otherwise employed under conditions requiring an effective seal against fluid penetration.
In my above-identified prior application and patent I have disclosed a fluidtight fastener whose interengageable coupling members, e.g. helicoidal or meandering filaments of thermally set linear polyamide, are permeated by an elastomeric mass of synthetic resin which forms a pair of elongated sealing strips contacting each other in the closed condition of the fastener. The elastomeric material, such as foamed polyurethane, may also envelop the stringer tapes conventionally serving as carriers for the respective slide fastener halves.
The general object of mu present improvement is to provide a method which enhances the sealing effect of the elastomeric strips disclosed in my prior patent mentioned above.
An ancillary object is to provide a method of making a slide fastener with improved endstops effectively coacting with the elastomeric strips to prevent leakage at the extremities of the fastener.
It is also an object of this invention to provide an expeditious method and apparatus for mass-producing such fasteners.
These objects are realized, pursuant to my present invention, by providing mutually complementary, yieldably interlocking formations along confronting longitudinal surfaces of the two elastomeric strips by extrusion of the latter concur rently about the interconnected coupling elements. These formations, advantageously comprising one or more grooves and one or more ribs extending over the full length of the strips, should have sufficient shear strength to resist transverse stresses which otherwise might deform the fastener halves as to create a leakage path. Thus, besides making the assembly truly fluidtight, these formations also serve as effective reinforcements for the coupling members of the fastener.
According to another feature of my invention, a slider coacting with the two fastener halves and straddling the associate elastomeric strips is in positive engagement with the aforementioned formations by being rovided, on opposite sides of its web, with a recess and a projection respectively mating with the male and female portions of the elastomeric seal.
According to still another feature, an endstop for the slider may be formed from the same or similar elastomeric material as the two sealing strips in such manner as to envelop the extremities of the latter, thereby firmly anchoring these strips to the underlying stringer tapes at locations beyond the ends of the coupling members. If the fastener forms a closure for a slit closed at both ends, two such endstops may be provided. In that case, also, the endstop confronting the fastener in the closure position thereof may be formed with a resilient bumper, e.g. of soft rubber or of more porous elastomeric material, interposed between two transversely spaced channels which receive the extremities of the two sealing strips, this bumper engaging the slider (specifically the blunt end of its preferably wedge-shaped web) in its terminal position to prevent undue deformation ofthe strips.
In the manufacture of the slide fastener assembly with its sealing strips by an extrusion process, I prefer to use a profiled blade to form the complementary parts.
The joint extrusion of the strips may be followed by a shaping operation (e.g. between rollers) to which the sealing strips may be individually subjected in a partially cured state after being separated from each other. In accordance with a further development of this technique, pursuant to my present invention, the separation of the extruded strips is accomplished, with the aid of a suitably shaped blade, along a transverse median line having a looped portion which conforms to the cross-sectional outline of the complementary sealing formations.
The invention will be described in greater detail with reference to the accompanying drawing in which:
FIG. I is a cross-sectional view of a closed slide fastener embodying the invention;
FIG. 2 is a view similar to FIG. 1, showing the fastener in its open state;
FIG. 3 is a cross-sectional view of a slider associated with the fastener of FIGS. 1 and 2;
FIG. 4 is a top view of the slider of FIG. 3 along with an adjoining endstop;
FIG. 5 is a cross-sectional view through the endstop, taken on the line V-V of FIG. 3;
FIG. 6 is a view similar to FIG. 4, showing the slider juxtaposed with a second endstop;
FIG. 7 is a perspective view of part of a slide fastener assembly according to the invention, with the sealing strips partly broken away; and
FIG. 8 is a cross-sectional view of the assembly in the process of extrusion.
The slide fastener shown in the drawing, generally designated 1, comprises a pair of conventional, interengageable coupling members 3a, 3b in the form of helicoidal fila ments, e.g. of nylon, stitched or otherwise fastened to a pair of stringer tapes 2a, 2b. The projecting loop portions or heads of each fastener half 3a, 3b, forming a row of teeth receivable in the gaps between the teeth of the opposite half, may be conventionally deformed (e.g. flattened) so as to exhibit resiliently interlocking projections 3c, 3d (FIG. 8). Each fastener half 3a, 3b is enveloped, except for the immediate vicinity of its teeth 3c, 3d, by an elastomeric sealing strip 50, 5b, preferably of foam plastic. The sealing strips are integrally extended at 4a, 4b to form coatings enveloping the tapes 2a, 2b. A longitudinal seal, generally designated 6, is provided by the interengagement of a longitudinal groove 7 on strip 5a and longitudinal rib 8 on strip 5b, the rib 8 being slightly undercut for a positive but releasable interlocking of these two formations. Formations 7, 8 extend over the entire length of the respective strips.
A slider 15, astride the strips 5a, 5b, is movable along the fastener 1 between a pair of endstops 10', 10'. Upon closure of the fastener slider 15 abuts the endstop 10 as shown in FIGS. 4 and 7; when the fastener is fully opened, the slider rests against the endstop 110" (FIG. 6). Each of these endstops is in the form of an elastomeric cap, e.g. of foamed polyurethane like the strips 5a, Sb, having integral lateral extensions 9b or 9a", 9b" which overlie the elastomeric layers 4a, 4b and are firmly secured thereto, advantageously by thermal bonding. Cap 10' has a pair of transversely spaced channels Illa, lllb receiving the corresponding (upper) extremities of strips 5a and 5b; cap 10' has a single such channel 11 accommodating the opposite (lower") extremities of the strips. Channels 11a and 11b are separated by a web 13 having an elastic pad 14 of soft rubber or plastic secured thereto.
Slider 15 consists as best seen in FIG. 3, of a curved upper plate 16 with depending flanges 16a, 16b, a lower plate 17 and an interconnecting web 18 having recesses 19a, 19b to guide the exposed heads of fastener members 3a, 3b. As best seen in FIG. 4, the web 18 is generally wedge-shaped and converges toward the bottom" endstop 10''; its blunt end bears against the bumper 14 in the terminal position of FIGS. 4 and 7. In addition, web 18 is provided on on side with a riblike projection 21 and on the opposite side with corresponding recess 22 in permanent engagement with groove 7 and the rib 8, respectively, of strips 50 and 5b which are straddled by the flanges 16a, 16b. A handle 20 is integral with the upper plate 16 of the slider.
Although the two sealing strips a, Sb with their extensions 40, 4b could be molded separately around tapes 2a, 2b and filaments 3a, 3b, I prefer to produce them by joint extrusion with the aid of a nozzle 23 as illustrated in FIG. 8. A blade 24, having a looped portion 24a, and a counterblade 25 in line therewith both extending generally along the longitudinal plane of symmetry of the fastener, are mounted in the nozzle 23 to sever the elastomeric mass into its strip portions 50, 5b. The molded strips, emerging from the nozzle along with the coupling members 3a, 3b imbedded therein, can then be further deformed before final hardening, e.g. with constriction of the groove 7 to compensate for the thickness of blade 24.
If the slider should be lost or destroyed, a temporary closure and a certain measure of protection against leakage can still be obtained by forcing the rib 8 into the groove 7 without interlocking of the fastener halves 3a, 3b.
1. A method of making a fluidtight slide fastener assembly, comprising the steps of forming a slide fastener unit from a pair of stringer tapes extending alongside one another and having respective elongated coupling elements affixed to said tapes and interfitting along the confronting edges thereof; continuously advancing said unit while extruding an elastomeric material around the interconnected coupling elements; and severing said material along the interfitted edges into a pair of interfitting profile strips with correspondingly profiled blade.
2. The method defined in claim 1 wherein the extruded material is severed along a transversely median plane at least along one side of the interconnected coupling elements.
3. The method defined in claim 2 wherein said elastomeric material is severed along both sides of the interconnected coupling elements.
4. The method defined in claim 2 wherein the extruded material is severed along said transverse median line which is formed with a looped portion conforming to profiled formations of the elastomeric strips.
5. The method defined in claim 4 wherein said elastomeric material is simultaneously extruded around the stringer tapes at least in the region of said coupling elements.
6. The method defined in claim 5 wherein said stringer tapes are fully embedded in the extruded material along the lengths of said coupling elements.
7. The method defined in claim 6 wherein the severing of the extruded material is terminated short of the length of the coupling elements and stringer tapes to form an endstop member for a slide fastener slider adapted to be received on said strips.
8. The method defined in claim 6 wherein said coupling elements each have a multiplicity of loops transverse to the tapes and forming a row of teeth separated by gaps to receive the teeth of the other coupling element, said elastomeric material being extruded into the interstices of said loops but leaving said teeth and gaps exposed.
9. ln apparatus for carrying out the method of claim 1, the improvement which comprises an extrusion die receiving said unit and adapted to form a shaped body of said elastomeric material therearound, and a thin profiled sheet metal blade in said die for severing said material to form said strips therefrom.
10. T he improvement defined in claim 9 wherein said blade has upper and lower blade portions engaging said material on opposite sides of said coupling elements.