GB2051221A - Improvements relating to sliding clasp fasteners. - Google Patents

Abstract

Tag (5) of a locking slider retracts a prong (19) from fastener elements near the base of one arm of the Y- channel. Prong (19) is the end portion of an S-shaped tongue (5) projecting from one end of a channel-shaped cap (6). The cap is a snap fit onto pillars (12, 14) at the ends of upper shield (2) and tongue (8) lies mostly within one cap channel, prong (19) projecting down through aperture (20) in the upper shield offset from the centre line. Curved root (17) spring-urges prong (19) into the locking position. Tag (5) retracts the prong before engaging notches (7) in the side- flanges of cap (6) and moving the slider. Projection of prong (19) is limited by shoulder (22) on the tongue which abuts upper shield (2). <IMAGE>

Description

SPECIFICATION Improvements relating to sliding clasp fasteners This invention reiates to sliding clasp fasteners.

It is concerned with sliding clasp fasteners of the kind having a body comprising upper and lower shields joined by a neck, forming a Y-shaped channel for two sets of interdigitating fastener elements, a cap fitted to the upper shield and having a locking prong projecting through an aperture in that shield, and a pull member or tag coupled to the cap so that when pulled it releases the prong against spring action from locking engagement with the fastener elements.

The fastener elements may be individual fingers or turns of coils. They are normally stitched to or woven integrally into tapes which themselves will be sewn into the garment or other article requiring fastening.

The main requirement from such fasteners is that they should lock securely and positively, or ratchet under strong pressure without damaging the fastener, and yet be easy to release. Other important considerations are that the slider should be made of as few discrete pieces as possible, three being the practical minimum, and each should as far as possible be of simple shape, readily die-cast, stamped or otherwise formed and susceptible to automatic assembly. It is the aim of this invention to provide such a slider.

According to the present invention there is provided a slider for a sliding clasp fastener of the kind described, wherein the locking prong is at the free end of a spring tongue projecting from one end of the cap and bent underneath the cap in a generally S-configuration, the pull member or tag being engaged below an intermediate portion of the tongue to retract the prong when pulled, and the prong and upper shield aperture being offset to one side of the centre longitudinal axis of the slider so that locking engagement will be made with one set of fastener elements in one arm of the Y-shaped channel.

Preferably the junction of the prong with the intermediate portion of the tongue provides a shoulder or abutment which, by engagement with the upper face of the upper shield, limits the penetration of the prong. The root portion of the tongue is conveniently narrower than the intermediate portion to provide a major part of the spring in the tongue. The prong will generally be square to the longitudinal axis of the slider and can be blunt-ended.

Preferably the cap is generally of inverted channel section, having a web and side flanges, with the tongue projecting from one end of the web thereof, notches are formed in the side flanges to receive the pull member or tag, and lugs at the ends of the side flanges are engaged without substantial play in lateral recesses in pillars upstanding from the upper shield towards each end of the slider body, the intermediate portion of the tongue in its relaxed state being laterally visible through said notches so that the pull member or tag, when pulled, engages that intermediate portion before the edges of the notches. At said one end there will generally be two spaced pillars between which the root section of the tongue is located.

Preferably, the upper ends of the side walls of the pillars are chamfered and the aperture has a divergent upwardly facing mouth, the cap being fitted by being pressed substantially perpendicularly to the plane of the upper shield with the lugs being spread by the chamfers and then snapping into said recesses, the divergent aperture mouth facilitating entry of the prong.

For a better understanding of the present invention one embodiment will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side elevation, partly in section, of a slider for a sliding clasp fastener, Figure 2 is a plan view of the body of the slider of Figure 1, Figure 3 is a plan view of a blank from which the cap of the slider of Figure 1 is formed, and Figure 4 is a diagram illustrating the interengagement of coil fastener elements and a locking prong of the slider.

The slider has an integrally formed body 1 including an upper shield 2, a lower shield 3 and a neck 4 joining the shields and forming between them a Y-shaped channel for the interdigitating fastener elements (Figure 4). The fastener action is conventional and will not be described further.

A pull tag 5 is coupled to the body 1 via a cap 6. This cap is pressed from a sheet metal blank as shown in Figure 3 into inverted channel form with notches 7 in its side walls for the pull tag and with a tongue 8 projecting from one end of the channel web. This tongue will be described in more detail below. At the ends of each side wall of the cap there are lugs 9 and 10, and when assembled the lugs 9 engage in recesses 11 in the outer sides of a pair of pillars 12 upstanding from the wider, neck end of the upper shield 2. The lugs 10 similarly engage in lateral recesses 13 in a pillar 14 at the other end of the upper shield. The pillars 12 are mirror images of each other with respect to the longitudinal centre plane A of the fastener body and their outer side walls have chamfers 1 5 at their upper ends.The pillar 14 is also disposed symmetrically with respect to centre plane A and is similarly chamfered at 1 6. The lugs 9 and 10 match the recesses 11 and 13 fairly closely and allow the cap virtually no longitudinal or vertical play.

The tongue 8 is formed into a generally Sconfiguration largely within the channel of the cap 6. It has a curved spring root portion 1 7 located between the twin pillars 12, a wider, considerably less springy, middle portion 1 8 which slopes upwardly towards the pillar 14 and then curves downwardly, in lateral view through the notches 7, towards the upper shield 2, and an extremity 1 9 which forms a blunt-ended prong. This prong projects through an aperture 20 in the upper shield and is square to the longitudinal axis of the slider. The portions 17 and 18 are symmetrically bisected by the longitudinal centre plane A, but the prong 19, and consequently the aperture 20, are offset to one side.The junction between portions 17 and 18 provides shoulders 21 which, although they do not necessarily abut the pillars 12, are wider than the gap between them and would act as stops against undue distortion. The junction between the portion 18 and the prong 19 provides a wide, downwardly facing shoulder 22 which normally abuts the upper face of the shield 2 and limits downward penetration of the prong.

The middle portion 18 goes through an aperture in the pull tag 5, which also embraces the cap 6, and since in the normal relaxed state the curved upper part of the middle portion 18 is below the apex of each notch 7, a pull on the tag will first act on the tongue 8 and withdraw the prong 19 from projecting below the upper shield 2. When the tag 5 engages the notches 7, the slider will be free to move. As soon as the tag is released, the spring action of the root portion 17 restores the prong 19 to the projecting position.

The aperture 20 has a V-shaped mouth 23, divergent to the upper face of the shield 2 to facilitate entry of the prong. Below this there is a throat 24 whose side 25, facing away from the neck and along the stem of the Y-channel, provides an abutment against which the prong 19 is urged when the fastener is subject to a release force generated by a pulling apart of the portions of the tapes with disengaged fastener elements.

In the relaxed state there may be a spacing x (see Figure 4) between the prong 19 and the abutment 25, and its extent determines the release force required to generate ratcheting. This is the term applied to the jumping of the prong from one element to the next when a strong separating or release force is applied to the tapes.

If x is zero so that the prong slides over the face 25, there will be total lock. The prong will have no scope to distort. As x increases, so the prong 1 9 has more room to flex before being arrested.

When it flexes, its penetration between fastener elements is reduced and correspondingly the force needed to release the fastener. By suitable choice of x a pre-ordained release force can be achieved.

The engagement of the prong 1 9 with the fastener elements is towards the root of one arm of the Y-shaped channel. The prong co-operates with one coil only and the gap between turns allows it positive and deep penetration, but limited by the shoulder 22.

For assembly of the fastener, the cap 6 is shaped and, with the pull tag 5 in position, is arranged directly above the upper shield 2. It is then pressed vertically downwards, the prong 19 penetrating the aperture 20 and the lugs 9 and 10 meeting the chamfers 1 5 and 1 6 to spread the side walls of the cap slightly before they snap into the recesses 11 and 13.

It will be understood that the side to which the prong and upper shield aperture are offset is arbitrary: the lock is as effective one side as the other.

Claims (9)

1. A slider for a sliding clasp fastener of the kind described, wherein the locking prong is at the free end of a spring tongue projecting from one end of the cap and bent underneath the cap in a generally S-configuration, the pull member or tag being engaged below an intermediate portion of the tongue to retract the prong when pulled, and the prong and upper shield aperture being offset to one side of the centre longitudinal axis of the slider so that locking engagement will be made with one set of fastener elements in one arm of the Y-shaped channel.

2. A slider as claimed in claim 1 , wherein the junction of the prong with the intermediate portion of the tongue provides a shoulder or abutment which, by engagement with the upper face of the upper shield, limits the penetration of the prong.

3. A slider as claimed in claim 1 or 2, wherein the root portion of the tongue is narrower than the intermediate portion to provide the major part of the spring in the tongue.

4. A slider as claimed in claim 1, 2 or 3, wherein the prong is square to the longitudinal axis of the slider and is blunt-ended.

5. A slider as claimed in any of the preceding claims, wherein the cap is generally of inverted channel section, having a web and side flanges, with the tongue projecting from one end of the web, notches are formed in the side flanges to receive the pull member or tag, and lugs at the ends of the side flanges are engaged without substantial play in lateral recesses in pillars upstanding from the upper shield towards each end of the slider body, the intermediate portion of the tongue in its relaxed state being laterally visible through said notches so that the pull member or tag, when pulled, engages that intermediate portion before the edges of the notches.

6. A slider as claimed in claim 5, wherein at said one end there are two laterally spaced pillars between which the root section of the tongue is located.

7. A slider as claimed in claim 6, wherein the upper ends of the side walls of the pillars are chamfered and the aperture has a divergent upwardly facing mouth, the cap being fitted by being pressed substantially perpendicularly to the plane of the upper shield with the lugs being spread by the chamfers and then snapping into said recesses, the divergent aperture mouth facilitating entry of the prong.

8. A slider substantially as hereinbefore described with reference to the accompanying drawings.

9. A sliding clasp fastener with a slider as claimed in any preceding claim.