Sliding clasp fastener

A sliding clasp fastener has a pair of interengageable open-end fittings whereby the fastener stringers may be completely separated one from the other. Each fitting comprises hooking means at each side of a plane parallel to the tapes and transversely opposed surfaces to overlap surfaces of the other fitting.

BACKGROUND OF THE INVENTION 
This invention relates to a sliding clasp fastener of the open-end type. 
The term "open-end type sliding clasp fastener" as used throughout this 
specification means a sliding clasp fastener which comprises two 
stringers, each stringer having a series of coupling elements secured to 
an edge of a carrier tape, the two series of coupling elements being 
interengaged and disengaged by movement of a slider therealong, and a pair 
of interengageable releasably connectable end fittings secured one to each 
of the tapes adjacent the end of its series of elements whereby when the 
slider has been moved to disengage the two series of elements, said 
fittings may be disengaged to separate the stringers completely one from 
the other and then re-engaged to re-assemble the stringers. 
SUMMARY OF THE INVENTION 
According to the present invention, an open-end type sliding clasp fastener 
comprises a pair of interengageable open-end fittings, each fitting 
comprising two hooking means positioned one at each side of a plane which 
is substantially parallel with the plane of the carrier tapes, the hooking 
means of the pair of end fittings being mutually engageable in one 
longitudinal direction, each fitting further comprising transversely 
opposed surfaces to overlap surfaces of the other fitting so that, when 
the two series of coupling elements and the pair of end fittings are 
interengaged, the hooking means prevent separation of the end fittings 
laterally of the tapes, the transversely opposed surfaces of the end 
fittings prevent separation thereof transversely to the plane of the 
tapes, and the interengagement of the coupling elements prevents 
longitudinal separation in the opposite longitudinal direction. 
In one form of the invention the two hooking means of each fitting are 
offset one from the other so that the sides of the two hooking means 
provide the transversely opposed surfaces, the offset in the two fittings 
being in opposite lateral directions when the fittings are interengaged so 
that the sides of the hooking means of one fitting laterally overlap sides 
of the hooking means of the other fitting. 
In another form of the invention, the two hooking means of each fitting are 
transversely aligned and extend beyond transversely opposed sides of a rib 
defined by the fitting towards the other fitting so that, when the 
fittings are interengaged, sides of the two hooking means of each fitting 
laterally overlap the sides of the rib of the other fitting. 
The invention provides open-end fittings which are particularly suitable 
for fasteners having series of individual coupling elements moulded onto 
carrier tapes since the fittings may be moulded in tools which open and 
close in the same direction as tools employed for moulding the coupling 
elements. In fact, the tools for the fittings may be actuated 
simultaneously with the tools for the coupling elements so that the 
fittings are moulded at the same time as the coupling elements, thereby 
avoiding separate and subsequent operations to provide open-end fittings 
on the tapes.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIGS. 1 and 2, a sliding clasp fastener comprises two 
stringers 10 and 11 which each comprise a carrier tape 12 having a series 
of discrete coupling elements 13 moulded onto one of its edges. The series 
of elements of the two stringers are interengageable and disengageable by 
movement of an unshown slider mounted on stringer 11 in well-known manner. 
The lower ends of the stringers 10 and 11 carry respective open-end 
fittings 14 and 15 which are secured to their respective carrier tapes 12 
adjacent the lower ends of the series of coupling elements 13. The 
open-end fittings 14 and 15 may be of plastics or metal, conveniently 
moulded or cast directly onto the carrier tapes 12, but alternatively they 
may be made separately and then secured to the tapes, for instance, by 
welding or clamping. 
The open-end fitting 14 comprises hooking means in the form of two hooking 
portions 16 and 17 which are downwardly directed away from the coupling 
elements 13 and form two recesses 18 and 19. In this embodiment each 
hooking portion occupies half the thickness of the open-end fitting 14. 
The hooking portions 16 and 17 are positioned at each side of a plane 
coincident with the plane of the carrier tapes 12 with the two hooking 
portions offset one from the other laterally of the carrier tape to 
present transversely opposed surfaces 20, 21 and 21a. 
Above the hooking portions 16 and 17, two laterally extending projections 
22 and 23 are appropriately shaped on their upper surfaces to engage with 
the lowermost coupling element 13 on stringer 11 when the stringers 10 and 
11 are assembled. 
The open-end fitting 15 comprises hooking means in the form of two hooking 
portions 24 and 25 upwardly directed towards the coupling elements and 
forming two recesses 26 and 27. As with the open-end fitting 14, each 
hooking portion 24 and 25 occupies half of the thickness of the open-end 
fitting 15 and lies at a respective side of a plane coincident with the 
plane of the carrier tapes, and the two hooking portions 24 and 25 are 
offset one from the other laterally of the carrier tape 12 to present 
transversely opposed surfaces 28, 28a and 29. The lower end of the 
open-end fitting 15 has transversely extending feet 30 (one only being 
shown) to provide a stop for the slider and prevent it sliding completely 
off the lower end of the stringer 11. As particularly seen from FIG. 1, 
the lower end portion of the open-end fitting 15 has a concave edge 31 to 
provide a clearance 32 from the open-end fitting 14 to enable the lower 
ends of the open-end fittings 14 and 15 to move towards one another when 
the slider is located against the feet 30. The offset arrangement of the 
hooking portions in each open-end fitting, and the shape of the hooking 
portions and their recesses, are designed to enable the two open-end 
fittings 14 and 15 to be interengaged as shown in FIG. 1 with the hooking 
portions 16 and 24 lying at one side of the plane of the carrier tapes 12, 
and the hooking portions 17 and 25 lying at the other side of the plane of 
the carrier tapes. Whilst the hooking portions 16, 17:24, 25 prevent 
separation of the open-end fittings 14 and 15 laterally of the carrier 
tapes 12, the transversely opposed side surfaces 20, 21, 21a:28, 28a, 29 
laterally overlap one another to prevent separation of the open-end 
fittings perpendicularly to the plane of the carrier tapes. 
The above described open-end fittings are particularly suitable for a 
fastener of which the coupling elements are moulded between mould parts 
which move only perpendicularly to the plane of the carrier tapes since 
the open-end fittings 14 and 15 can be similarly moulded and thus lend 
themselves to being formed simultaneously with the coupling elements 13. 
This obviates the need for a separate moulding operation to provide the 
open-end fittings 14 and 15. 
Furthermore, the design of the open-end fittings 14 and 15 enable the 
stringers 10 and 11 to be assembled in use even when the lower ends of the 
stringers are not initially correctly aligned; in other words a greater 
extent of misalignment of the lower ends can be tolerated immediately 
prior to moving a slider from the open-end fittings to assemble the 
stringers when compared with conventional open-end type fasteners. 
In the second embodiment illustrated in FIG. 3, an open-end fitting 31 
comprises two hooking portions 32 and 33 which, in contrast to those of 
the first embodiment, are aligned one with the other in a direction 
perpendicular to the plane of the carrier tape 12 and are spaced-apart by 
the thickness of a rib 34. Parts of the hooking portions 32 and 33 extend 
across and beyond opposite sides of the rib 34 away from the associated 
carrier tape 12 and are positioned at each side of the plane of the 
carrier tape. Similarly, a cooperating open-end fitting 35 comprises two 
hooking portions 36 and 37 aligned one with the other in a direction 
perpendicular to the plane of the carrier tape and spaced-apart by the 
thickness of a rib 38. Parts of the hooking portions 36 and 37 extend 
across and beyond opposite sides of the rib 38 away from the associated 
carrier tape 12 to lie at each side of the plane of the carrier tape. 
When the two open-end fittings 31 and 35 are interengaged, the hooking 
portions of each fitting straddle the rib of the other fitting, and the 
hooking means of both fittings mutually engage at each side of the tapes 
with transversely opposed inner surfaces of the hooking portions of one 
fitting overlapping transversely opposed sides of the rib of the other 
fitting. Consequently, the hooking portions 32, 33, 36 and 37 prevent 
separation of the open-end fittings 31 and 35 laterally of the carrier 
tapes 12, whilst the overlap of the hooking portions 32, 33, 36 and 37 and 
the ribs 34 and 38 prevent separation of the open-end fittings 31 and 35 
perpendicularly to the plane of the carrier tapes 12. 
This second embodiment is particularly appropriate for a fastener 
comprising moulded coupling elements having a slot in their coupling heads 
adapted to receive the edge of the opposite tape when the fastener is 
assembled. The mould arrangement for the elements can thus be adopted to 
provide the space between pairs of hooking portions of each open-end 
fitting. 
In further embodiments not shown in the drawings, the hooking portions of 
each open-end fitting may be positioned at each side of a plane which is 
substantially parallel to but is not coincident with the plane of the 
tapes. Such an arrangement may be employed for example on a fastener of 
which each stringer has a series of coupling elements secured entirely on 
one face of a tape. The transversely opposed surfaces may be mutually 
inclined laterally to the plane of the tapes.