WO1985000145A1

WO1985000145A1 - Paper fastener

Info

Publication number: WO1985000145A1
Application number: PCT/GB1984/000231
Authority: WO
Inventors: Anthony Victor Hardiman
Original assignee: Cartwright Brice & Co Ltd
Current assignee: Cartwright Brice & Co Ltd
Priority date: 1983-06-28
Filing date: 1984-06-28
Publication date: 1985-01-17
Anticipated expiration: 1985-12-28
Also published as: GB8504740D0; GB8317498D0; EP0151592A1; GB2176150A; GB2176150B

Abstract

An all-plastic paper fastener for insertion through standard punch holes (28) at 8 cm spacing (or other spacing of not more than 10 cm) utilises a base (4) with integral prongs (6) a compressor bar (10) and a slider (12) which engages yet is separate from the compressor bar (10). The slider (12) is elongate and can completely conceal the prongs (6) turned down onto the compressor bar (10). It can also slide right off the compressor bar (10) to which it is retained by engaging undercut hooks (14) along side edges of the compressor bar (10).

Description

PAPER FASTENER

FIELD AND BACKGROUND OF THE INVENTION

This invention relates to paper fasteners, of the kind with a base portion from which two prongs extend through a pair of spaced apart holes in the margin of papers, then are bent down onto an upper bar, usually called a compressor bar, and are clipped to it. Such fasteners generally are dimensioned to fasten through holes at a standard spacing of 8cm, although other spacings such as 7cm are known. The compressor bar may have formations such as cut out apertures at its ends to locate it relative to the prongs.

SUMMARY OF THE PRIOR ART

Traditionally such fasteners have been made wholly of metal, and in that form they are of very widespread use. Plastic equivalents to such metal fasteners have been proposed in UK Patents 1525997, 1489223, 1494316, 1368407 and 917356. These proposals have utilised two- part constructions rather than the traditional, four- part metal constructions, in which the prongs are held down by two small metal sliders captive on the compressor bar. In UK 1525997 for example the prongs are held under static parts formed on the compressor bar; in UK 1489223 the prongs turn outwardly and snap into holes at the ends of the compressor bar. SUMMARY OF THE INVENTION

The present invention provides a paper fastener made of plastic, having a construction made with three (or possibly more) parts, namely a base portion with integral prongs extending from it to pass through spaced holes in the papers, a compressor bar, and at least one slider to hold the prongs turned down onto the base portions. In contrast to the traditional metal clips, the slider(s) is (are) elongated in the longitudinal - 2 -

direction-of the compressor bar, and cover a length of the prongs turned down onto the compressor bar.

Preferably the slider(s) is (are) separable from the compressor bar, whereas those of the traditional metal clip are not. Preferably the or each slider is long enough to extend across at least one of the spaced holes, as well as covering a length of turned down prong.

In preferred forms of the fastener some or all of the following features are also employed: i) the prongs are flat plastic strips moulded integrally with a wider flat base portion; ii) each prong is joined to the base through a hinge of relatively reduced stiffness; iii) the compressor bar has an aperture at each end portion, .and the strips pass through these; iv) these apertures are holes set in from the ends of the compressor bar; v) the free portions of the prongs are both held down by means of a single free slider long enough to extend from one aperture in the compressor bar to the other, i.e. long enough to extend the full distance between the points where the prongs are turned down over the compressor bar; vi) engagement of the slide and bar is effected by means of undercut grooves on one of them, preferably the compressor bar, into which the other one engages; vii) the slide lies within the width of the bar, and preferably is narrower than the bar; and viii) the fastener is dimensioned to fasten papers through punched holes at a spacing of 10cm or less, in particular 8cm or 7cm.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of this invention will now be described with reference to the accompanying drawings, in which Figs. 1, 3 and 4 are top views onto the base portion, compressor bar and slide respectively;

Fig. 2 is an enlarged section on the line II-II of Fig. 1 showing a living hinge;

Fig. 5 is an end view of the fastener holding a bundle of papers (shown in phantom);

Fig. 6 is a perspective view of the upper parts of the fastener, with the slide partly pulled out; and

Fig. 7 is a section on line VII-VII of Fig. 5.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The fastener has a first part 2, shown in Fig. 1 and comprising a base portion or bottom strip 4 and a prong 6 joined to each end through a hinge 8. The whole part 2 is moulded from plastic material. Both the bottom strip 4 and the prongs 6 are flat, and of uniform thickness except at the hinges where the thickness is less to give greater flexibility and from a so-called living hinge 8 (Fig. 2 ) .

The fastener also has a compressor bar 10 shown in Fig. 3 and a slider 12 shown in Fig. 4. At each end portion the compressor bar 10 has hooks 14 along its side edges which are undercut (as best seen from Fig. 5). The slider 12 has a top 16 and sides 18 and is dimensioned so that the sides 18 fit into the undercuts and then are held against the bar 10 by the hooks 14. A central channel 20 is defined by the top 16 and sides 18 of the slider and ribs 22.are provided on the top 16 to act as finger grip areas.

The compressor bar 10 has holes 24 set in slightly from its ends, and whose centres are 8.0cm apart. The distance between the living hinges 8 is also 8.0cm.

For use a bundle of papers 26 to be held together is punched (with a standard two-hole punch) to provide holes 28 which are 8.0cm apart. The prongs 6 are then inserted through these holes 28, and through the holes 24 in the compressor bar 10, until the papers 26 are sandwiched between the compressor bar 10 and the strip 4 as shown in Figs. 5 and 7. The free portions of the prongs are then bent down by hand onto the compressor bar 10, as shown in Fig. 3. ^t XΕEJT Next the slider 12 is inserted under the undercut hooks 14 at one end and slid along over the prongs until it engages under the other pair of hooks 14. The free portions of the prongs are thereby held in place, entirely concealed within the channel 20 of the slider 12.

If the bundle of papers is not too thick the end portions of the prongs 6 will overlap, as shown in Figs. 6 and 7, and the channel 20 isdeep enough to accommodate this. The ends of the slide 12 are slightly rounded, which facilitates insertion under the hooks 14. The slide and the compressor bar are dimensioned so that the hooks 14 grip the slide gently, and hold it in place by friction. The use of plastic for all parts of the fastener means that sharp edges and corners can be avoided.

In use the slider 12 completely conceals the distal parts of the prongs 6 turned down onto the compressor bar. Moreover, the elongate slider not only covers these lengths but also extends across the apertures 24, and the. spaced-apart punched holes 28 in the paper 26.

When the slider 12 is slid to release the prongs, it slides out beyond the region between the holes 28. Because the hooks 14 extend beyond the holes 24 in the compressor bar, the tip of the slider 12 remains slidingly engaged with the undercut hooks 14 even after the prongs are released. However the slider 12 can then be slid completely off the compressor bar 10.

The fastener as shown is effective, avoids the sharp edges often found with pressed metal products is simple to fit and remove, and presents a neat appearance.

All three parts of the fastener are made by injection moulding. The part 2 is preferably made from impact resistant polypropylene homopolymer. A small amount of co-monomer may be tolerated, but polypropylene copolymers are apt to give unsatisfactory hinges 8. The compressor bar 10 is moulded from high-tensile ABS. The slider 12 does not need to have the strength of the other and can be made, from polypropylene homo- or co-polymer,

-OMPI

Claims

We Claim:

1. A paper fastener made wholly of plastic material and comprising: a base portion and a pair of flexible prongs integral with said base portion, said prongs extending from spaced points on said base portion, for passing through a pair of spaced holes in the papers, a compressor bar to extend between the spaced holes, overlying said base portion with the papers sand¬ wiched between the base portion and the compressor bar. at least one slider to hold the distal parts of the prongs down onto the compressor bar said slider being elongate, and the compressor bar and said slider having co-operating shapes which enable said slider to slidingly engage on the compressor bar with the length of the slider extending in the longitudinal direction of the compressor bar,

-the co-operating shapes of the compressor bar and slider defining space for a length of at least one prong between said slider and the compressor bar said at least one slider being slidable along the compressor bar to cover over and hold, or to release lengths of the prongs turned down onto the compressor bar.

2. A paper fastener according to claim 1 wherein said compressor bar has undercut hooks and said slider is slidingly engagable in the undercuts of the hooks.

3. A paper fastener according to claim 1 wherein said slider is slidable outward beyond the region of the compressor bar between the spaced holes, onto which the prongs turn down, so as to slide wholly off of said prongs.

4. A paper fastener according to claim 1 wherein a single slider is dimensioned to extend over both of ^_ ϊ. -__J O I said spaced holes in the papers and between the spaced holes so that said single slider can conceal the turned down distal portions of both said prongs.

5. A paper fastener according to claim 4 wherein 5 the compressor bar has a pair of spaced regions, along which extend undercut hooks, separated by a central region without said hooks, and said single slider is slidingly engagable in the undercuts of the hooks.

6. A paper fastener according to claim 1 wherein ]_0 said slider is arranged to extend across at least one of said spaced holes in the papers, while also covering a length of at least one of said prongs turned down onto the compressor bar.

7. A paper fastener according to claim 1 wherein -_5 said prongs are flat strips, each joined to said base portion through a hinge of greater flexibility than the strip.

8. A paper fastener according to claim 1 wherein said prongs join to said base portion at points spaced

20 apart by no more than 10cm.

9. A paper fastener according to claim 1 wherein said slider is narrower than said compressor bar.

10. A paper fastener according to claim 1 wherein said compressor bar comprises a pair of spaced formations

25 to engage said prongs where the prongs emerge from the holes in the papers, the compressor bar also having undercut hooks along its side edges, proximate the said formations and extending outwardly beyond the region of the compressor bar between the spaced apertures,

30 onto which region the prongs turn down, whereby the slider or sliders are slidable outwardly beyond said regions.