Paper-clips

Abstract

The present invention discloses and claims a paper-clip which is injection moulded in one piece from resilient plastics material. The clip has outer clamping limbs and an inner clamping member which lie in substantially the same plane when in an unstressed state, the inner clamping member comprising two clamping portions which are interconnected at one end by a connecting portion which is resistant to bending, the clamping portions having a low resistance to torsion and having smaller cross section than bridge portions which extend transversely, one from each of the other adjacent ends of the clamping portions, the ends of the transverse bridge portions remote from each other being interconnected by the outer clamping limbs which extend around the inner clamping member, the inner clamping member having, contiguous to its end remote from the transverse bridge portions, a support member which lies substantially in the plane of the inner clamping member and which extends into the vicinity of the transverse bridge portions, the transverse bridge portions being resistant to bending and the support member together with the connecting portion forming a unit which is resistant to bending in its central region and less resistant to bending in its outer regions.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a paper-clip having outer clamping limbs and an inner clamping member which lie substantially in the same plane when in the unstressed state, the inner clamping member being connected to the outer clamping limbs by two transverse bridge portions of greater length. Also, the end of the inner clamping member remote from the transverse bridge portions has contiguous thereto a support member which lies substantially in the plane of the inner clamping member and which extends into the vicinity of the transverse bridge portions.

Such a paper-clip, made from wire or sheet metal, is known. However, in this paper-clip, all the parts have the same cross sections and the inner clamping members are separated from one another. The known paper-clip does not provide an adequate clamping force and, when clamping together thick documents, tends to spring away from the latter. Furthermore, it is very susceptible to breakage and is expensive to manufacture.

Furthermore, the applicant's German Pat. Specification No. 1,221,608 discloses a paper-clip made from plastics material. It is relatively narrow, so that only a relatively narrow gap is formed between the inner clamping limb and the outer clamping limbs. Only a relatively small number of sheets can be clamped together by means of such paper-clips. It has transpired that the thickness of the pad of sheets to be clamped to one another has to be sufficiently small for the pad to bend between the inner and outer clamping limbs. If the clip is used on a thicker pad of sheets, the free ends of the clamping limbs stand off from the pad of sheets and there is the risk of the paper-clip sliding off.

So-called "butterfly clips" are known for the purpose of clamping together thicker documents. These butterfly clips are relatively complicated structures made from steel wire and have two inter-crossing clamping portions which grip the pad of sheets from both sides. These clips are expensive, susceptible to corrosion, and, owing to their sharp ends, tend to damage the documents. Furthermore, they are extremely disadvantageous when sent by post, and some of them are no longer permitted to be sent by post.

The object of the invention is to provide a paper-clip which is suitable for clamping together very thick bundles of sheets. It is to be simple to manufacture and readily applied and must not damage the bundles of sheets or other articles which come into contact with it.

SUMMARY OF THE INVENTION

In according with the present invention, this object is achieved in that the paper-clip is injection moulded in one piece from resilient plastics material, and comprises an inner clamping member, outer clamping limbs, a support member and bridge portions, two clamping portions defining said inner clamping member with a connecting portion interconnecting said clamping portions at one end thereof, the clamping portions having a low resistance to torsion and the connecting portion having a high resistance to bending, said bridge portions which have a larger cross section than the clamping portions, extending transversely one from each of the other adjacent ends of the clamping portions and said outer clamping limbs extending between the ends of the transverse bridge portions remote from each other, around said inner clamping member, the support member extending from the end region of the clamping portions remote from the transverse bridge portions towards the transverse bridge portions, the support member together with the connecting portion forming a unit which is resistant to bending in its central region and less resistant to bending at its outer regions and the outer clamping limbs, bridge portion, inner clamping member and support member all lying substantially in the same plane when in an unstressed state whereby the inner clamping member can be displaced from the outer clamping limbs to grip sheets therebetween.

The paper-clip constructed in accordance with the present invention may be manufactured in a particularly simple manner in the form of a part which is injection moulded from plastics material. A powerful clamping effect is produced between the support member and the outer clamping limbs when the paper-clip is applied to a pad of documents. The long transverse bridge portions assume a sloping position without bending to any substantial degree. The clamping effect is produced by torsion of the clamping portions and by combined torsion and bending in the outer clamping limbs. It is important for the support portions to have support points which are located relatively near to the transverse bridge portions and thus hold the pad of documents in the edge region thereof. However, the support member should be connected to the rest of the clip only in the region of the connecting portion resistant to bending, so that the torsion of the clamping portions is not hindered and the support member does not bend away from the pad of documents. As a result of these measures, the clip constructed in accordance with the present invention abuts firmly against both sides of the pad of documents without standing off from the pad of documents in the region remote from the edge thereof.

To facilitate the slipping-on of the clip, the support member is of preferably arrow-shaped configuration in the direction in which the paper-clip is slipped on. For the same reason, the outer clamping limbs may converge in a V-shape from the outer ends of the transverse bridge portions. This construction is also particularly suitable, spatially, to an arrow-shaped configuration of the support member, since pressure and counter-pressure are exerted in adjacent regions on both sides of the pad of documents. Alternatively, the outer clamping limbs may form a V-shape semi-circular shape or any other suitable shape to interconnect the remote ends of the transverse bridge portions.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be further described by way of example, with reference to the accompanying drawings in which:

FIG. 1 is a frontal view of one embodiment of a paper-clip constructed in accordance with the present invention,

FIG. 2 is a side elevation of a pad of documents with the paper-clip illustrated in FIG. 1, slipped thereon, as seen in the direction of the arrow II in FIG. 3,

FIG. 3 is a view seen in the direction of the arrow III in FIG. 2, and

FIG. 4 is a section taken on the line IV--IV in FIG. 2.

DESCRIPTION

FIG. 1 shows a paper-clip which is constructed in accordance with the present invention and which is injection moulded from a relatively resilient plastics material. The paper-clip 11 is manufactured in the form of a predominantly closed loop of substantially triangular configuration. Its dimensions in the transverse direction are substantially equal to the dimensions which appear as perpendicular dimensions in FIG. 1.

In detail, the paper-clip 11 has two outer clamping limbs 12, 13 which converge in the center in the form of a V. They meet at a junction 14 at which the paper-clip has a widened portion. As will be explained later, this is advantageous in order to ensure satisfactory joining and coagulation of the plastics material during injection moulding. The outer clamping limbs 12, 13 have their smallest width contiguous to the junction 14 and widen from this point. The ends of the outer clamping limbs remote from the junction 14 merge into transverse bridge portions 15, 16 which are of relatively great width. The junction between the outer clamping limbs 12, 13 and the transverse bridge portions 15, 16 is provided with outer and inner chamfered portions.

Na inner clamping limb 17 extends at right angles to the transverse bridge portions 15, 16 in the interior space formed in the paper-clip 11 between the outer clamping limbs 12, 13 and the transverse bridge portions 15, 16. The transverse bridge portions 15, 16 are in alignment with each other when in the unstressed state and are separated by a slot 18 which extends to a relatively great distance into the inner clamping limb 17 in the center thereof, so that the inner clamping limb 17 is divided into two clamping portions 19, 20.

Compared to the other dimensions of the paper-clip, these clamping portions are relatively thin and non-resistant to torsion. For this purpose, they have a cross section whose width dimensions are not substantially greater than the dimensions lying at right angles to the drawing plane in FIG. 1. In the present embodiment they have a relatively square cross section. Alternatively, however, they could have a circular cross-sectional construction.

The ends of the two clamping portions 19, 20 directed towards the junction converge in a connecting portion 21. The connecting portion 21 is relatively long in the direction of the clamping limb 17 and is the full width of the two clamping portions, but does not have the slot 18. It is resistant to bending, so that its shape is not impaired by the torsional forces acting upon the clamping portions. A support member is formed on the connecting portion 21 in the lower region thereof and has two arms 22, 23 which extend in an arrow-shaped or V-shaped configuration towards the junction between the transverse bridge portions and the outer clamping limbs. In other words, the support member 22, 23 forms a V which lies in the same position within the V formed by the outer clamping limbs 12, 13 but subtends a greater angle. The ends of the arms 22, 23 form support points 24, 25 which, in the illustrated embodiment, are in the form of circular thickened portions. For the rest, the arms 22, 23 become somewhat narrower towards the support points. The support member comprising the two arms 22, 23, which are interconnected by way of the connecting portion 21 resistant to bending, forms a relatively stiff, self-contained unit. However, in the present embodiment, the outer regions of the arms 22, 23 are somewhat resilient, in order to ensure uniform contact pressure along the entire length of the arms. For this purpose, in addition to the slightly converging configuration of the arms, the thickness of the material of the arms can be reduced somewhat towards the ends thereof. For the rest, the entire paper-clip may have a uniform thickness of material and a substantially rectangular cross section, this being important for the manufacture and particularly for the configuration of the casting mould.

Advantageously, in a manner known per se, the dead head, i.e. the injecting of the plastics material into the mould, can be effected in the region of the connecting portions. Thus, it is located in a reinforced portion subjected to low material stress, so that no detrimental effects are caused by irregularities in the material which are particularly prevalent at this point. The same applies to the connection point 14 where the material can satisfactorily coalesce in the widened portion.

FIGS. 2 to 4 show the paper-clip 11 after it has been applied to a bundle of documents. It will be seen that the bundle of documents may be very thick relative to the size of the paper-clip 11. Thus, a bundle of documents comprising more than 100 sheets (about 1 cm) can be clamped together by, for example, a paper-clip having dimensions of about 5 cm in both length and width, without the paper-clip being subjected to inadmissible stresses and without parts of the clip e.g. points 14 and 21 standing off from the end regions of the bundle of sheets or tending to slip therefrom. As may be seen from FIGS. 2 to 4, the outer clamping limbs 12, 13 abut satisfactorily against the underside of the bundle of sheets. The outer clamping limbs 12, 13 thus act as combined torsion and bending springs by virtue of the fact that they endeavor to return the transverse bridge portions 15, 16 from their oblique position, shown particularly in FIG. 3, into the position in which all parts of the paper-clip are located in one plane. The transverse bridge portions 15, 16 are positioned obliquely across the edge of the bundle 26 of sheets without bending to any substantial extent. Thus, as may be seen particularly in FIG. 4, the clamping portions 19, 20 in particular are very greatly torsioned. Thus, it is essential for the clamping portions 19, 20 to have a low resistance to torsion, since their torsional length is very small in comparison to the outer clamping limbs. These portions (19, 20) form the critical point, and their low-resistance to torsion enables the clip to be used with a thick bundle of sheets without breaking. This is remarkable, since one would assume that the critical point would have to be of particularly strong construction. However, relatively great resistance to bending should be maintained transversely of the main plane of the paper-clip, since otherwise the inner clamping limb could bend so that it could tend to "spread apart", i.e. to stand off from the bundle of sheets. The support member does not hinder the torsion, since it engages the bundle only in the region of the connecting portion 21. Nevertheless, its support points 24, 25 are located in the vicinity of the edge 27 of the bundle of sheets (FIG. 2), so that "spreading apart" is also prevented. By virtue of the bending resistance of the connecting portion 21, the arms 22, 23 of the support member remain substantially flat, and the entire length of the support portion can exert a good clamping effect upon the top of the bundle of sheets. Owing to the configuration of the support member, a force is produced which opposes the "spreading apart" of the clip and which at the same time ensures that the outer clamping limbs 12, 13 abut satisfactorily against the underside of the bundle of sheets. The slipping-on of the paper-clip is considerably facilitated by the special configuration of the illustrated and described paper-clip in the form of two V-shaped members. When the paper-clip is applied to the edge 27, i.e. when only the regions of the junction 14 and the connecting portion 21 engage the bundle of sheets, spreading-apart occurs which, however, diminishes as the paper-clip is pushed further onto the bundle of sheets until good abutment across the entire region is ensured when the paper-clip has been slipped fully onto the bundle of sheets.

It may be mentioned that the described paper-clip is of fully symmetrical construction, so that it may be used in both directions, for example in the position which would result if, in FIG. 3, the inner clamping limb 17 were located below the bundle of sheets and the outer clamping limbs 12, 13 were located above the bundle of sheets. This is impossible in the case of the known "butterfly clips" for thick bundles of sheets. Once such a clip has been used on a thick bundle of sheets, a permanent set gap is formed between the upper and lower clamping limb, so that a thinner bundle of sheets can no longer be clamped in a satisfactory manner. This disadvantage is entirely avoided in the present invention since, on the one hand, such permanent deformation rarely occurs by virtue of the advantageous configuration and, on the other hand, if such deformation occurs, the clip could be used in the reverse direction in which case the clamping effect is then particularly great. Many modifications of the illustrated and described embodiment are possible within the scope of the invention. Thus, for example, the clip could have a U-shaped or semi-circular configuration, although the illustrated V-shape is particularly advantageous.

Claims

I claim:

1. A paper-clip which is injection moulded in one piece from resilient plastics material, said clip comprising an inner clamping member, outer clamping limbs, a support member and bridge portions, two clamping portions defining said inner clamping member with a connecting portion interconnecting said clamping portions at one end thereof, the clamping portions having a low resistance to torsion and the connecting portion having a high resistance to bending, said bridge portions which have a larger cross section than the clamping portions, extending transversely one from each of the other adjacent ends of the clamping portions and said outer clamping limbs extending between the ends of the transverse bridge portions remote from each other, around said inner clamping member, the support member extending from the end region of the clamping portions remote from the transverse bridge portions towards the transverse bridge portions, the support member together with the connecting portion forming a unit which is resistant to bending in its central region and less resistant to bending at its outer regions and the outer clamping limbs, bridge portion, inner clamping member and support member all lying substantially in the same plane when in an unstressed state whereby the inner clamping member can be displaced from the outer clamping limbs to grip sheets therebetween.

2. A paper-clip according to claim 1, wherein the support member is of arrow-shaped configuration in the direction in which the paper-clip is to be slipped on.

3. A paper-clip according to claim 2 wherein the support member has two limbs which taper from the connecting portion towards their ends, on which ends are located thickened portions.

4. A paper-clip according to claim 1, wherein the outer clamping limbs converge in a V-shape from the said remote ends of the transverse bridge portions to a junction.

5. A paper-clip according to claim 4, wherein the outer clamping limbs, taper from the said remote ends of the transverse bridge portions towards their junction.

6. A paper-clip according to claim 4 wherein in a manner known per se, the junction of the outer clamping limbs is widened during manufacture of the paper-clip from injection-moulded plastics material, so that the junction is wider than adjacent portions of the outer clamping limbs.

7. A paper-clip according to claim 1, wherein the width of the paper-clip measured in the direction of the transverse bridge portions corresponds substantially to its dimensions at right angles thereto.

8. A paper-clip according to claim 1 wherein the clamping portions have a cross section with substantially equal dimensions in both directions.