GB2305108A - A slotted earring clasp and method of manufacture - Google Patents

Abstract

A butterfly clasp 2 for an earring is provided which has a base 8, a through hole 10 formed in the centre of the base and two resilient scrolls 4 each containing a slot 12, 14 formed parallel to the axis of the centre hole extending from either side of the base and in contact when not in use. An earring shank passes through the hole, is received between the scrolls and is located in the slots. The slots prevent lateral movement of the shank relative to the clasp. The scrolls are created so that there is an elastic deformation prior to the insertion of the earring shank.

Description

IMPROVEMENTS RELATING TO EARRINGS The present invention provides an improved butterfly clasp for earrings and a method of manufacturing said clasp.

It is well known to use butterfly clasps to secure earrings which have an elongate shank to pass through the ear lobe. Known clasps are formed from an elongate pressing of thin sheet metal and comprise a base with a hole to receive the earring's shank and two scrolls, one on each side of the base.

The scrolls resiliently engage the shank of the earring, preventing the shank from falling from the ear lobe.

Such clasps do not tend to grip the earring shank as effectively as desired. A consequence of this sub-optimal gripping is that many earrings are lost due to the clasps falling from the shank, thus releasing the earring.

Various attempts have been made to improve the strength with which the clasp grips the earring shank. For instance it is well known to provide a shallow groove along the longitudinal axis of the scrolls in which the shank lies when the clasp is in place. To provide the groove it is necessary to stamp the sheet metal which forms the scroll, before it is rolled. The groove is an attempt to prevent lateral movement of the shank relative to the clasp which will tend to release the clasp from the shank.

A problem with this solution is that, as will be appreciated by a man skilled in the art, to provide a groove in a sheet of metal makes it difficult to roll the metal to produce the desired scrolls.

Therefore, the groove cannot be as deep as necessary to securely locate the shank and the groove solution is compromised.

It is an aim of the present invention to provide an improved clasp which securely locates the shank of an earring.

According to a first aspect of the invention we provide a clasp to receive an elongate element, such as the shank of an earring, the clasp being formed from one piece of resilient metal and comprising a base having a hole to receive said element, resilient elements positioned on each side of the hole to make frictional engagement with the element when in use, said resilient elements containing slots having parallel portions extending along lines parallel to the axis of said hole such that, in use, the elongate element locates in the parallel portions of the slots and is thereby restrained from lateral movement.

Such a clasp provides better location of the shank of an earring. Lateral movement of the shank relative to the clasp is restrained as the shank is registered more securely in the slots provided in the resilient elements.

Although in the preferred embodiment the resilient elements contain slots, the slots may be replaced with holes. In use, the elongate element will locate in a diameter of the holes in the resilient elements and will then be restrained from lateral movement. Using such holes in the resilient elements is not the desired solution. As will be appreciated, it will be harder to locate the hole on the resilient element, so as to be in a position to engage the elongate element, than it will be to locate a slot.

Preferably the resilient elements comprise arm portions extending from the base in opposite directions that have been rolled into a scroll formation.

A groove may be provided in the shank which cooperates with the slots in the resilient means.

Such a groove will provide secure location of the clasp on the shank in a longitudinal direction relative to the shank.

Preferably the groove in the shank is annular in shape. Thus, the orientation that the clasp is placed onto the shank, so as to engage the groove in the shank and the holes in the resilient means does not matter.

The clasp may be made from sheet metal such as silver or gold.

According to a second aspect we provide a process for the manufacture of a clasp as defined hereinbefore comprising providing an elongate flat strip of metal, forming a hole in the centre thereof and forming slots lying in a common axis on either side of the hole and spaced apart therefrom, rolling the portion of the strips containing the slots toward the centre to form two scrolls, the degree of rolling being such that the slots lie in portions of the scrolls extending along lines parallel to the axis of the centre hole.

The flat strip may comprise an individual element, formed by stamping or other suitable process from a sheet of metal, or may comprise one of an array of such strips, formed in a sheet of metal and separated therefrom after scrolling in a known manner.

Preferably rolling is carried out such that the scrolls, on completion of the rolling, are in contact with each other in a plane extending through a diameter of the hole.

The forming of said scrolls may comprise rolling the elongate portions of said strip consecutively so that it each extends beyond halfway across the base, relative to where said resilient means joins said base of said clasp. An advantage of this is that when both resilient means have been formed they will butt against each other with a force, produced by an elastic displacement of each of the resilient means. It will be appreciated that once both of the resilient means have been formed, neither of the scrolls will be able to extend beyond halfway as described hereinbefore as each of the resilient means will abut the other.

A further advantage of forming the clasp in such a manner is that a shank placed between the resilient means will be gripped more securely as in their rest state the resilient means are already elastically deformed. Therefore an extra displacement caused by inserting the shank between the resilient means, will cause a greater force to be applied to the shank than is usual.

An embodiment of the invention will now be described in detail, by way of example, with reference to the accompanying drawings in which: Figure 1 is a plan view of a prior art solution for locating a shank within a clasp; Figure 2 is a plan view of a clasp according to the present invention secured to the shank of an earring; Figure 3 is a view of a sheet of metal from which some of the stages of manufacture of the clasp of the present invention can be seen; Figure 4 is a side view of the clasp of the present invention after one of two scrolls have been formed; and Figure 5 is a cross sectional view of a clasp for an earring according to the invention.

Figure 1 shows a plan view of a prior art clasp 30 with scrolls 32,34 and a shank 36 inserted between the scrolls 32,34. As can be seen from the plan, shallow flat grooves 36,38 have been formed in the scrolls 32,34. The clasp 30 has a width, indicated by x, of about 2.03mm (0.080") and the shank 36 has a diameter of about 0.686mm (0.027").

As will be appreciated such grooves 36,38 offer little or no improvement over a clasp with no grooves. Both a clasp with no grooves and a clasp 30 with flat grooves have two points of contact 40.1,40.2 with the shank 36. With only two points of contact it is easy to rotate the clasp 30 relatively to the shank 36 about an axis perpendicular to the longitudinal axis of the shank 36 and thus release the clasp from the shank, consequently releasing the earring from the ear lobe.

Figure 5 shows the clasp 2 according to the present invention, in which resilient elements or scrolls 4,6 attach to a base 8 and meet along a plane above the centre of the base 8. At the centre of the base 8, also in the plane along which the scrolls contact, is a hole 10 which is adapted to receive a shank of an earring (not shown) . Two slots 12,14 are present, one in each of the scrolls 4,6, toward the end portion of the scrolls 4,6 away from the base and are positioned so that they are at the point of contact of the scrolls 4,6.

Figure 2 shows the clasp 2 of Figure 5 viewed in plan. The holes 12,14 are visible in the scrolls 4,6. The shank 16 of an earring (not shown) contacts the scrolls 4, at four points 18-1 to 18-4, providing superior location of the shank 16 within the clasp 2 when compared with clasps of the prior art as described hereinbefore. It will be appreciated that contacting the shank at four points will assist in preventing lateral movement, or rotation, of the clasp 2 relative to the shank 16.

Prior to insertion of the shank 16 into the clasp 2, the scrolls 4,6 are arranged as viewed in Figure 5, that is the scrolls touch along a plane.

As the shank 16 is passed through the hole 10, in the base 8, the scrolls 4,6 are forced apart. The elastic deformation produced, as the scrolls 4,6 are forced apart, causes the shank 16 to be gripped with a greater force than previous designs. As can be seen in Figure 2, once the shank 16 is between the scrolls 4,6, the scrolls 4,6 no longer touch.

Providing an annular groove (not shown) in the shank 16 at the point where the scrolls 4,6 contact the shank 16 increases the location of the shank 16 within the clasp.

Figures 3 to 5 show some of the stages of manufacture of the clasp according to the present invention.

Figure 3 shows a strip of metal 42 from which the scroll is formed. The left of the Figure shows the metal with no processes performed on it and the right of the Figure shows the metal once nets, that is 2 dimensional strips from which the 3 dimensional clasps are formed, for the clasp have been removed.

Firstly the hole 44 in the centre of the base of the net is punched. Then as the strip progresses through the machine slots 46, corresponding to the slots 12,14 of Figure 1, are punched in. Finally the net for the clasp is removed as can be seen from the hole 48.

Once the net has been removed the elongate portions 50,52 are formed into the scrolls 4,6 of Figure 5 by rolling inwards.

In this embodiment one scroll of each net, scroll 6, is rolled before the other. As will be seen from Figure 6, scroll 6 has been rolled so that it extends for more than half of the base of the clasp. Scroll 4 is then rolled in a similar manner to scroll 6, that is, so that if scroll 4 were the only scroll it would extend for more than half of the base. However, as best seen in Figure 5, with both scrolls 4,6 formed an interaction occurs causing each scroll 4,6 to extend over only half of the base. The interaction being caused by reactive forces set up in the two scrolls 4,6.

The scrolls 4,6 already have an elastic deformation caused by the interaction between them, but further deformation to the scrolls 4,6 is caused by inserting the shank 16 between them. This further deformations requires a greater force than if there were no initial elastic deformation. As a result the shank is gripped more securely than if both scrolls are merely bent inwards so that they meet above the centre of the base, with no elastic deformation present in the scrolls prior to insertion of the shank.

Claims (13)

1. A clasp to receive an elongate element wherein the clasp is formed from a single piece of resilient metal and comprises a base having a hole to receive said element, resilient elements integral with the base positioned on each side of the hole to make frictional engagement with the element when in use, said resilient elements containing slots having parallel portions extending along lines parallel to the axis of said hole such that, in use, the elongate element locates in the parallel portions of the slots and is thereby restrained from lateral movement.

2. A clasp according to claim 1 in which the resilient elements comprise arm portions extending from the base in opposite directions and wherein each arm portion is in the form of a scroll.

3. A clasp according to claim 1 or claim 2 in which, in use, the clasp co-operates with a circumferential groove in the elongate element.

4. A clasp according to any preceding claim fabricated from sheet metal.

5. A clasp according to claim 4 fabricated from silver or gold.

6. A process for the manufacture of a clasp according to claims 1 to 5 comprising providing an elongate flat strip of metal, forming a hole in the centre thereof and forming slots lying along a common axis on either side of the hole and spaced apart therefrom, rolling the portion of the strips containing the slots toward the centre to form two scrolls, the degree of rolling being such that the slots lie in portions of the scrolls extending along lines parallel to the axis of the centre hole.

7. A process according to claim 6 in which the flat strip comprises an individual element, formed by stamping or other suitable process from a sheet of metal.

8. A process according to claim 6 in which the flat strip comprises one of an array of such strips, formed in a sheet of metal and separated therefrom after scrolling.

9. A process according to any of claims 6 to 8 in which the scrolls, on completion of the rolling, are in contact with each other.

10. A process according to claim 9 in which the scrolls are in contact in a plane extending through a diameter of the hole.

11. A process according to any of claims 6 to 10 in which the forming of the scrolls comprises rolling the elongate portions of said strip consecutively so that each extends beyond the centre hole.

12. A clasp substantially described herein with reference to Figures 2 to 5.

13. A process for the manufacture of an earring clasp substantially as described herein.