GB2026595A - Two-part snap fastener - Google Patents

Abstract

A two-part snap fastener primarily intended for fastening the ends of a necklace has a first box-like part (10) housing a U-shaped leaf spring (13), the ends of which are directed towards an open end of the box-like part and are provided with hook members (19). A second part (11) of the fastener has a pair of arcuate guide edges (22) which engage the hook members and force them inwardly as the first and second parts are pushed together. The resiliently biased hook members (19) then spring apart into fastening engagement with latch parts (23) provided at the ends of the guide surfaces.The hook members can be released by manual pressure on projecting portions (18) of the leaf spring (13). <IMAGE>

Description

SPECIFICATION Two-part snap fastener This invention relates to a two-part snap fastener and although primarily developed as a relativeiy small fastener for use with jewellery, it is also envisaged that the invention may have a wider application to provide a two-part snap fastener for use in many other fields.

According to the invention there is provided a two-part snap fastener comprising a first part and a second part, the first part having a pair of hook members which are resiliently biased in opposite senses, the second part having a pair of latch parts and a pair of guide means which are so shaped as to tend, when the first and second parts are moved towards each other, to move the hook members in opposite directions against their respective latch parts, with which they are caused to engage and retained in fastening engagement by their respective resilient biases.

The hook members may be resiliently biased apart and the guide means will then tend to guide them towards each other as the first and second parts are moved towards each other.

The resilient biasing of the hook means is preferably provided by leaf spring means. Each hook means may be integral with the leaf spring means by which it is resiliently biased.

A single leaf spring of generally U-shape may provide both of said leaf spring means.

The leaf spring means biasing each of the hook members may include a portion usually extending outwardly of the fastener and adapted to be urged inwardly manually, whereby the hook members may be released from the respective latch parts with which they are engaged.

The latch parts may comprise recesses provided in the guide means.

One embodiment of the invention will now be described by way of example only with reference to the accompanying drawings in which: FIGURE 1 is a longitudinal section through a fastener embodying the invention in the fastened or engaged condition, FIGURE 2 is a similar section showing the two parts of the fastener having been separated.

The fastener shown in the drawings may be used as a fastener for a necklace for example and, as shown in the unfastened condition in Figure 2, a first part 10 of the fastening would be attached to one end of the necklace and a second part 11 would be attached to the other end of the necklace. The first part 10 comprises an outer casing 12 having a leaf spring means 13 mounted inside by means of its own resilience. The expression "leaf spring" and "leaf spring means" as used in this description and the appended claims are intended to include any form of spring constructed of resilient strip or wire and are not intended to be limited to such springs when made of metal strip. However, in the example shown in the drawings, the generally U-shaped leaf spring 13 is formed of resilient metal strip.

The leaf spring 13 is housed in a casing 12 which is of box-like formation having large faces 1 5 which are slightly spaced apart and are linked by edge faces 16. Each edge face 16 has a slot 24. The casing 1 2 is completed by an end wall 25, the opposed end of the casing being open at 26.

The leaf spring is held in the casing by its own resilience and includes arcuate intermediate portions 1 8 which project outwardly through the slots 24 of the edge faces 1 6. The limbs 17 of the U-shaped leaf spring abut the walls of the casing towards the end wall 25. The free ends of the leaf spring are curved outwardly to afford hook members 19 which, in Figure 2, can be seen bearing on the interior of the casing at the edge faces 16.

When the fastener is in the condition shown in Figure 2, finger pressure on the arcuate intermediate portions 18 of the leaf spring will force the hook members 19 towards each other against the resilient bias of the spring. When released, the hook members will then be urged apart.

The second part 11 of the fastener is formed from a strip of metal 20 having a turned up thumb piece 14 at one end. The other end is bifurcated to provide a pair of limbs 21 which have inwardly facing curved surfaces. The curved surfaces provide guide means 22, the function of which will later be described. At the inner end of each guide means 22, a recess is provided to form a latch part 23.

The fastener is operated by presenting the strip 20 forming the second part 11 of the fastener to the open end 26 of the first part 1 0. Relative movement of the first and second parts towards each other causes the hook members 1 9 to abut against the ends of the limbs 21 of the second part and subsequently to ride along the guide means 22 until they reach the respective latch parts 23. The resilience of the spring 13 is all the time tending to push the hoole members apart and, on reaching the latch parts, they become engaged with the latch parts and are retained by the resilient bias in fastening engagement.It will be seen from Figure 1 of the drawings that the dimensions of the first and second parts of the fastener are such that the hook members reach the latch parts as the second pert of the fastener is pushed fully home in the first part.

To release the fastener, it is firstly necessary to release the hook members from the latch parts and this is done by manually exerting pressure on the arcuate portions 1 8 of the leaf spring, tending to force the hook members inwardly and disengage them from the latch parts 23. The first and second parts of the fastener can then be separated, for which reason the thumb part 1 4 is provided on the second part of the fastener.

Although, in the example described, the leaf spring is integral with the hook members, this need not necessarily be the case and some other form of biasing means could be provided, either separate from or integral with the hook members.

Each hook member may be biased separately.

Furthermore, it is possible to use a reversed arrangement in which the hook members are normally urged together by the resilient bias and the guide means tend to force them apart and into engagement with latch parts. This arrangement may be suitable in particular where the second part of the fastener has a box-like form which can interfit telescopically with the first part.

Claims (8)

1. A two-part snap fastener comprising a first part and a second part, the first part having a pair of hook members which are resiliently biased in opposite senses, the second part having a pair of latch parts and a pair of guide means which are so shaped as to tend, when the first and second parts are moved towards each other, to move the hook members in opposite directions against their respective resilient biases and to guide them towards respective latch parts, with which they are caused to engage and retained in fastening engagement by their respective resilient biases.

2. A fastener according to Claim 1 wherein the hook members are resiliently biased apart and the guide means tend to guide them towards each other as the first and second parts are moved towards each other.

3. A fastener according to any preceding claim wherein the resilient biasing of the hook means is provided by leaf spring means.

4. A fastener according to Claim 3 wherein each hook means is integral with the leaf spring means by which it is resiliently biased.

5. A fastener according to Claim 4 wherein a single leaf spring of generaliy U-shape provides both of said leaf spring means.

6. A fastener according to any one of Claims 3 to 5 wherein the leaf spring means biasing each of the hook members includes a portion usually extending outwardly of the fastener and adapted to be urged inwardly manually whereby the hook members may be released from the respective latch parts with which they are engaged.

7. A fastener according to any preceding claim wherein the latch parts comprise recesses provided in the guide means.

8. A two-part snap fastener substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.