Structure of coupling head portion for coiled slide fastener element

Abstract: A coiled slide fastener element (1) made of a synthetic resin monofilament (m) has a coupling head portion (6), which has an enlarged width by forming bulging portions (5) so that firm coupling of a slide fastener can be realized.

Description: The present invention relates to a coiled slide fastener element made by bending a monofilament of synthetic resin so as to have an upper leg portion, a coupling head portion, a lower leg portion, and a connecting portion in succession, said coupling head portion including two opposite bulging portions, said bulging portions being relatively thick and having a gently-sloped, non-recessed contour, the slide fastener element further comprising two bent portions, said bent portions being substantially semi-circular in cross section and confronting each other. In a conventional coiled slide fastener element of this type (FR-A-2 094 005) the leg portions include bent portions made by pressing the monofilament vertically with respect to the slide fastener plane. Said bent portions include flat portions being in contact with each other. Said flat portions extend from the connecting portion and terminate short of the coupling head portion of each coupling element. When a pair of such coupling elements are coupled, the coupling head portions have somewhat weak lateral coupling force, and tend to be disengaged if pulled strongly in the lateral direction. With the foregoing problem in view, it is therefore an object of this invention to provide a structure of a coupling head portion for a slide fastener element which is resistant to lateral pulling force. According to the invention a coiled slide fastener element satisfying this requirement is characterized in that said bent portions adjoin said bulging portions and are provided at an inner side of said coupling head portion. This structure makes the shape of a hollow space defined between the upper and lower leg portions stable. Consequently, the most bulging points of the bulging portions are inserted into the hollow spaces of the mating coupling elements deeply and firmly so that the elements are coupled firmly. The bulging portions at the coupling head portion are mount-like with full and round slopes and large in thickness, thereby enlarging the coupling area and increasing the coupling force of the coupling head portion. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a part of a coiled slide fastener coupling element according to one embodiment of this invention; FIG. 2 is a side elevational view of the slide fastener element of FIG. 1; FIG. 3 is an enlarged cross-sectional view taken along line III-III of FIG. 2; FIG. 4 is an enlarged cross-sectional view taken along line IV-IV of FIG. 2; FIG. 5 is a side elevational view showing one example of a fastener stringer using the slide fastener element of this invention; FIGS. 6(A) and 6(B) are cross-sectional views of monofilaments. DETAILED DESCRIPTION One embodiment of this invention will now be described with reference to FIGS. 1 to 4. As shown in FIG. 1, a coiled slide fastener element 1, which is made by bending a monofilament of synthetic resin, comprises an upper leg portion 2, a coupling head portion 6, a lower leg portion 3, and a connecting portion 4, all of which are formed in succession by turning and bending the monofilament. The coupling head portion 6 includes bulging portions 5 and bent portions 8, 9. An inner side of the coupling head portion 6 and the upper and lower leg portions form a hollow space 7 for receiving a mating coupling head portion. The monofilament m composing the coiled slide faster element 1 is either circular or oval in the cross section as shown in FIG. 6(A) or 6(B). The circular or oval monofilament m is turned and bent to form the coupling head portion 6. At the coupling head portion 6, the monofilament becomes substantially semi-circular in the cross section, taken along line III-III in FIG. 2, as shown in FIG. 3, and serve as bent portions 8, 9. The bent portions 8, 9 confront each other via their flat portions 10, 11 which are nearly or actually in contact with each other. The monofilament is pressed at the inner side of the coupling head portion to form bulging portions 5 on opposite sides of the coupling head portion 6. The bulging portions 5 are mount-like with gentle slopes and large in thickness, thereby increasing the coupling area of the coupling head portion to realize firm coupling. The coiled slide fastener element 1 of the foregoing structure may be woven into a fastener tape t1 during weaving as shown in FIG. 2, or may be attached to a slide fastener tape t2 by sewing or by weaving as shown in FIG. 5. According to this invention, the coupling head portion has an enlarged width due to the bulging portions which are gently sloped, so that firm coupling of a slide fastener can be realized. Therefore, the slide fastener can remain coupled even when a strong lateral pulling force is applied thereto.

Claims: A coiled slide fastener element (1) made by bending a monofilament (m) of synthetic resin so as to have an upper leg portion (2), a coupling head portion (6), a lower leg portion (3), and a connecting portion (4) in succession, said coupling head portion (6) including two opposite bulging portions (5), said bulging portions (5) being relatively thick and having a gently-sloped, non-recessed contour, the slide fastener element further comprising two bent portions (8, 9), said bent portions (8, 9) being substantially semi-circular in cross section and confronting each other via flat portions (10, 11) thereof, said flat portions being substantially in contact with each other, characterized in that said bent portions (8, 9) adjoin said bulging portions (5) and are provided at an inner side of said coupling head portion (6).

Inventors: MATSUSHIMA HARU, MATSUSHIMA, HARU
Applicants: YKK CORP, YKK CORPORATION
Application year: 1991
Main classification: A44B19
IPC codes: A44B19