Stringers For Fasteners

Abstract

A plastic fastener comprises two stringers. Each stringer includes a plurality of longitudinally spaced plastic engaging elements. The engaging elements of each stringer are interconnected via a plastic strip in which are embedded threads whereby each stringer is a unitary structure of molded plastic material. Each engaging element of each stringer extends transverse to the axis of the stringer and is provided with teeth or hooks at its both ends for meshing with engaging elements of the other stringer.

Description

THIS invention pertains to fasteners and more particularly to stringers for fasteners using molded plastics.

An object of the invention is to provide an improved fastener wherein it is not necessary to provide hems or flaps on the material to hide the fastener from view.

Another object of the invention is to provide an improved slide fastener wherein stops are not required on the slide fastener per se for the slider.

A further object of the invention is to provide slide fasteners wherein the stringers are sold in strips or rolls which are then cut to the desired length so that it is not necessary to stock standard lengths.

It is yet another object of the invention to provide a slide fastener which is easily attached to a piece of material by using a conventional sewing machine without special feet.

It is a still further object of the invention to provide an improved slide fastener which does not require the usual welted tapes for anchoring the teeth.

Briefly, the invention contemplates a stringer for a fastener. The stringer comprises a plurality of plastic engaging elements. The engaging elements extending in a longitudinally spaced sequence along the length of the stringer. Each engaging element has an upper end with at least one projection for meshing with similar projections of the engaging elements of the other stringer, and has a flat bottom end to rest adjacent to a surface of its associated piece of material. The stringer includes an array of threads extending at least longitudinally and fixed to the bottom ends of the engaging elements. The threads are surrounded by the same plastic material used for the engaging elements so that the stringer is an integral unitary structure of molded plastic material.

OTHER objects, the features and advantages of the invention will be apparent from the following detailed description of the invention when read with the accompanying drawings wherein:

FIG. 1 is a perspective view of one embodiment of a slide fastener for connecting two pieces of material using stringers in accordance with the invention;

FIG. 2 is a top plan view of one of the stringers of the slide fastener of FIG. 1;

FIG. 3 is a sectional view taken along the line 3--3 of FIG. 2;

FIG. 4 is a side view of a portion of the slide fastener of FIG. 1;

FIG. 5 is a front end view of the slider of the slide fastener of FIG. 4;

FIG. 6 is a perspective view of a slide fastener using stringers in accordance with another embodiment of the invention;

FIG. 7 is a side view of a portion of the pair of enmeshed stringers of the fastener of FIG. 6;

FIG. 8 is a bottom view of a portion of the pair of enmeshed stringers of the fastener of FIG. 6;

FIG. 9 is a bottom view of a portion of one of the stringers of FIG. 6;

FIG. 10 is a top view of a portion of one of the stringers of FIG. 6; and

FIG. 11 is a sectional view taken along the line 11--11 of FIG. 10.

IN FIG. 1, there is shown a slide fastener comprising: a first stringer 20 sewn with thread 22 to a first piece of material 24; a second stringer 26 sewn with thread 28 to a second piece of material 30; and a slider 32. Since each stringer is the same only the stringer 20 will be described in detail by making reference to FIGS. 1 to 4.

Stringer 20 comprises a plurality of engaging elements 34 extending in spaced relationship along its length. The engaging elements 34 are held in interspaced positions by interconnecting means 36. A typical element 34 has a base portion 38 with a flat bottom face 40 whose longitudinal ends are provided with notches at 42 to accommodate interconnecting means 36. It should be noted that with respect to the engaging element 34 its bottom is the end adjacent the material 24 and its top is the end remote therefrom as viewed particularly in FIG. 1. In fact, at least a portion of the bottom face 34 abuts flush with the material. Extending from base 38 and integral therewith are outside upright portions 44 and 46 and which span central portion 48. Cut in the faces of outside upright portions 44 and 46 are recesses 50 and 52, respectively. In the face of each recess there is an indentation 54 and 56, respectively. Transversely overhanging and integral with each of the upright portions 44 and 46 are projections or teeth 58 and 60, respectively. Passing through central portion 48 is a longitudinally widened hole 62 whose top edge is chamfered at 64 and cooperates with side chamfers 66 and 68 to provide ridges whose function is hereinafter described.

Each of the interconnecting means 36 comprises either a plurality of longitudinally extending textile threads or an open woven tape which is encompassable by plastic. During manufacture of the stringer 20 by a plastic molding operation the engaging elements 34 are molded from plastic while the threads are simultaneously encased so that upon setting an integral unitary structure is obtained. In other words, the threads or tape are embedded in a plastic strip.

Stringer 20 is sewn onto one surface of the edge of the material 24 by means of a sewing machine, with a "ramming" or base guide, with the needle thereof passing through either the holes 62 of engaging elements 34 or the space between the elements. The aforementioned ridges and chamfers divert the sewing machine needle to these points.

Slider 32 in FIGS. 4 and 5 is provided with a wedge shaped centerpost 70 extending between plates 72 and 74 having right angle bent edges such as 76. These edges extend inward to form channels to guide the engaging elements 34. A pivotable lever pull 78 is connected to plate 74 and via a connecting means and a spring (not shown) to pins 80 to move the latter inward or outward. When the pins extend inward they will engage indentations 54 (See FIG. 4) to lock slider 32.

In order to enhance the flexibility of the stringers 20 and 26, the interconnecting means 36 can be provided with perforations 37 (FIG. 2).

IN FIG. 6, there is shown a slide fastener comprising: a first stringer 120 sewn with thread 122 to a first piece of material 124; a second stringer 126 sewn with thread 128 to a second piece of material 130; and a slider 132. Since each stringer is the same only one stringer will be described in detail by making reference to FIGS. 7 to 11.

Stringer 120 comprises a plurality of engaging elements 134 extending in spaced relationship along the stringer length. The elements 134 are held in interspaced positions by interconnecting means 136.

A typical engaging element 134 comprises a transversely extending bridge or base portion 138 to the ends of which are connected upright portions 140 and 142. It should be noted that the upright portions do not completely extend along the length of the bridge portion but are set back to provide a recess wall 143 best seen in FIG. 6. In addition, the upright portions are cut back at 141 to provide a track for the slider. The top of each upright portion is provided with a hook portion 144. (See FIG. 7). Hook portion 144 has an inclined top surface 156 and a flat engaging surface 158 which intersect to define the hook edge. The hook portions 144 of an engaging element 134 are separated from each other by a channel 146. The bottom of each upright portion is provided with a flat surface 148 and 150 to rest flush against the material. (See FIG. 9). It should be noted that the upright portions 140 and 142 and bridge portion 138 surround the interconnecting means 136 whose bottom surface 137 (FIG. 11) is level with the bottom surfaces of the upright portions.

The interconnecting means 136 is a plurality of threads or an open woven tape embedded in plastic to provide the backbone for the stringer 120 and to define the positions and spacing of the engaging elements 134.

While the stringer 120 has been described as a plurality of distinct units it is preferably a one piece integrated structure made of plastic and textile threads.

The stringer 120 can be made by an extrusion process, an injection molding process or and such similar processes wherein the fluid plastic used to form the engaging elements also saturates the spaces between the threads or tape. In an injection molding process the threads or tape are placed in the mold and then the fluid plastic introduced. The mold is so designed that the wall of the cavity is flush with the portions of the threads or tape which are between the engaging elements, i.e., the portion 152 of FIG. 9. Thus the stringer remains flexible after the plastic has set. In an extrusion process, the portions 152 are temporarily made brittle and thereafter subject to a bending or similar operation so that the plastic between the threads fractures so that the stringer is flexible when used.

A fastener using the stringers 120 and 122 has several advantages. Relative lateral movement of the stringers is impeded because a side of the hook portions 144 of one stringer abuts against the recesses 143 and the interconnecting means 136 of the other stringer as can be seen in FIG. 7.

IN addition the hook portions 144 are contoured with an inclined top surface 156 and a flat engaging surface 158 so that a slider is not needed, if desired. In such a case, the stringers are aligned one on top of the other and pressed together starting at a first end and proceeding to the second end. The hook portions 144 of the engaging elements 134 will snap together because of the yieldability of the material as these elements slide over the surfaces 156. The closure is maintained because of the abutting of the flat surfaces 158. Locking at the second or upper end of the fastener can be accomplished by providing a smaller spacing between several of the engaging elements near the upper end so that the hook portions 144 are subject to more pressure just like in the case of conventional "snap" fasteners.

The contour also permits separation of the stringers by a peeling operation which starts at the second end.

When the stringers 120 and 126 are used with a slider 132 several points should be noted. The end stops for the slider are easily provided by making sure that hook portions 144 of several of the engaging elements at the ends of the slider are permanently set in abutting relationship.

If the fastener is to be used to close two pieces of material which are normally separated, such as a jacket front, the slider can be retained on one of the stringers by making that stringer slightly longer than the other. End stops can be provided in the form described above or by a transverse seam or welt provided on the material at the ends of the stringer.

When the fastener is used to open or close two permanently joined pieces of material, the bottom stop for the fastener is easily obtained by sewing a transverse seam 118 (See FIG. 6) through the overlapping material pieces 124 and 130 at the bottom end of the fastener. Thus the engaging elements at this end remain permanently enmeshed. This procedure can be used for fasteners with sliders as well as those without sliders.

The stringers are easily affixed to the material by a conventional sewing machine which sews along the central portion of the interconnecting means 136 and the bridge portion 138. When the bridge portion is sufficiently thin to be pierced by the needle while sewing, no special guide holes are needed. If the bridge portion is thick then chamfered guide holes such as shown in FIG. 2 can be used.

Claims

WHAT I claim is:

1. A fastener for connecting two pieces of material comprising a pair of stringers, each of said stringers comprising a plurality of engaging elements longitudinally spaced from each other along the axis of the stringer, each of said engaging elements extending in a direction transverse to the axis of said stringer, each of said engaging elements having a bottom surface with a portion of which is substantially flat to rest adjacent a surface of its associated piece of material, a pair of upright portions extending upward from said bottom surface, a bridge portion, each of said upright portions being at a different end or said bridge portion and spaced from each other so that a channel is provided between said upright portions, means for connecting the bridge portions of said engaging elements to the associated pieces of material so that the stringers are fixed to their associated pieces of material, at lease one projection on the end of each of said upright portions for meshing with similar projections on the upright portions of the engaging elements of the other stringer and interconnecting means for interconnecting the engaging elements along the bottom surfaces thereof, said engaging elements and said interconnecting means being made from the same material to form a unitary structure.

2. The fastener of claim 1 wherein said material is a plastic and within said interconnecting means there are embedded threads that extend at least longitudinally along the length of said stringer.

3. The fastener of claim 2 wherein said threads are arrayed in the form of an open woven tape.

4. The fastener of claim 2 wherein the plastic of the interconnecting means is fractured.

5. The fastener of claim 1 wherein said projections are hook elements extending in the longitudinal direction of the stringer, the lateral spacing between the hook elements being such that said hook elements of the engaging elements of one stringer can straddle and abut portions of the sides of the engaging means of the other stringer.

6. The fastener of claim 5 wherein each hook element has a top surface which is inclined with respect to the plane of the stringer and a flat undersurface which is substantially parallel to said plane, said surfaces intersecting at an acute angle.

7. The fastener of claim 1 wherein the spacing between the projections of adjacent engaging elements at at least one end of said stringers is less than the spacing between the other engaging elements of the stringers.

8. The fastener of claim 1 wherein there is at least one indentation in the side of said upright portions for accepting the locking pin of a slider.

9. The fastener of claim 1 wherein the portion of said engaging element between said upright portions is provided with a through passageway for receiving a sewing machine needle.