GB1578024A

GB1578024A - Fasteners

Info

Publication number: GB1578024A
Application number: GB19513/76A
Authority: GB
Original assignee: ITW Ltd
Current assignee: ITW Ltd
Priority date: 1972-08-29
Filing date: 1976-05-12
Publication date: 1980-10-29
Also published as: GB1430093A; CA977129A; FR2351292B2; SE423757B; FR2351292A2; JPS4985457A; JPS5632487B2; AU5950873A; SE412967B; FR2198561A5; AU469885B2; DE2342681A1; SE7705487L

Description

PATENT SPECIFICATION

( 11) 1 578 024 ( 21) Application No 19513/76 ( 22) Filed 12 May 1976 ( 61) Patent of Addition to No 1430093 dated 24 Aug 1973 ( 23) Complete Specification Filed 12 May 1977 ( 44) Complete Specification Published 29 Oct 1980 ( 51) INT CL 3 GO 9 F 3/03 ( 52) Index at Acceptance B 6 P L 4 B ( 72) Inventor: COLIN WILLIAM FREDERICK CLINCH ( 54) IMPROVEMENTS RELATING TO FASTENERS ( 71) We, ITW LIMITED, a British company, previously of 470-474 Bath Road, Cippenham, Slough SL 1 6 BJ, Berkshire, and now of Darville House, 4 Oxford Road East, Windsor, Berkshire, SL 4 5 DR do hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the

following statement:-

The present invention relates to improvements in tamperproof shackle seals of the kind described and claimed in our British patent no 1 430 093.

According to that invention, a tamperproof shackle seal is a one-piece plastics moulding, and comprises a strap, a plug at one end of the strap and a socket at the other end of the strap; the plug having a leading end and a shoulder which faces away from said leading end; the socket having a sleeve-like wall which is closed at one end and has an open mouth at its other end; a number of resilient fingers fixed at first ends thereof to the wall and extending generally axially away from the mouth so that their remote ends are located in the socket; a first portion of the socket lying adjacent to the mouth, and a portion of the plug which in use co-operates with that first portion, having substantially similar non-circular internal and external outlines respectively, when viewed axially; and at least a part of said internal outline of the first portion lying radially outwards of an internal outline of an immediately adjacent second portion of the socket to define thereby a further shoulder which faces the mouth; whereby insertion of the plug into the socket causes the fingers to be flexed radially outwards until they can spring back for their remote ends to abut the shoulder and hold the plug captive in the socket, insertion of a tool to occasion subsequent flexing of all the fingers being prevented by the further shoulder.

Although seals of the kind defined above have been found to be valuable in many respects, a practical difficulty has been encountered in their manufacture in that the moulds do not always fill, with the result that the seals, particularly at the so-called remote ends of the resilient fingers, are not completely formed Naturally, if this happens the seals are useless and have to be scrapped for recycling An object of the present invention, therefore, is to reduce the rate of spoilage due to "short moulding" to an economically acceptable level.

In accordance with the present invention, a tamperproof shackle seal is a one-piece plastics moulding, and comprises a strap, a plug at one end of the strap and a socket at the other end of the strap; the plug having a leading end and a shoulder which faces away from the said leading end; the socket having a sleeve-like wall which is closed at one end and has an open mouth at its other end; a resiliently deformable and circumferentially continuous latching throat including at least three symmetrically disposed and substantially planar teeth which converge towards one another in the direction axially away from the mouth, a first end of the latching throat being fixed to the wall and free ends of the teeth presenting a polygonal outline for the latching throat, when viewed axially; a first portion of the socket lying adjacent to the mouth, and a portion of the plug which in use co-operates with that first portion, having substantially similar non-circular internal and external outlines respectively when viewed axially; and at least a part of said internal outline of the first portion lying radially outwards of an internal outline of an immediately adjacent second portion of the socket to define thereby a further shoulder which faces the mouth; whereby insertion of the plug into the socket causes the teeth of the latching throat to be flexed until they can spring back for their free ends to abut 00 r 1) tn ( 19) 1 578 024 the shoulder and hold the plug captive in the socket, insertion of a tool to occasion subsequent flexing of all the teeth of the latching throat being prevented by the further shoulder.

A particularly preferred seal embodying the present improvement will now be described, by way of example only, with reference to the accompanying drawings, in which:Figure '1 is a fragmentary plan of an improved seal, the socket being seen in open form as initially moulded; Figure 2 is a fragmentary elevation, the right half including a section taken along the line II-II in Figure 1; Figure 3 is a section taken along the line III-III in Figure 1; Figure 4 is a section taken along the line IV-IV of Figure 2; and, Figure 5 is a fragmentary underneath view of merely the socket as shown in Figure 2.

A presently preferred seal is shown in the accompanying Figures in its as-moulded condition, and consists of a strap 10 having a plug 12 at one end and a socket 14 at the other To lock the shackle, the plug 12 is pushed into the socket 14 after loops to be secured (not shown) have been threaded onto the strap 10 The one-piece seal can advantageously be injection moulded in a high melt material such as nylon 6 6, or in a low melt material such as polypropylene which has been reinforced with suitable fillers to increase its heat distortion temperature, and increase its resistance to rewelding It has been found that various fillers in the polymer present a barrier to heat-re-sealing, and thereby resist rewelding after tampering A currently preferred example of a filler which has been found to be suitable for this purpose is talcum powder To make the seal operative for use a circular flap 16, which is attached by a web 20 to a sleeve-like wall 18 of the socket, is hinged through 180 to overlie the upper end of the socket 14 The remaining circumferential edge of the flap 16, which is a close neat fit over said upper end of the socket, is then securely sealed to the wall 18 by ultrasonic welding.

When the shackle has been applied and the plug has been pushed home into the socket, the plug cannot be rotated relatively to the socket because a portion 22 at its base is oval shaped as seen best by reference to Figure 4 Its length (major axis of the oval) is substantially twice its width, and it fits in a tightly co-operating countersunk entrance portion formed adjacent to the mouth, or open end, 24 of the socket The oval portion 22 thus constitutes a 'co-operating" portion of the plug 12 Shoulders 25 face the open end 24, as shown in Figure 5 and are defined between an oval outlined portion which constitutes a first portion of the socket, and an adjacent portion having a barrel-shaped outline, which constitutes a second portion of the socket and, in use, receives a barrel-shaped portion 23 of the plug.

Three teeth 26 are carried on one end of an axially-extending tube which is separated from the wall 18 for most of its length by an annular groove 28, but is integrally formed with the wall 18 adjacent the pair of shoulders 25 The teeth 26 are symmetrically spaced at an included angle of 600, and converge towards one another in the direction (upwards as shown in Figure 2) axially away from the mouth 24 Although it is preferred that the latching throat includes the tube, which has a tendency to turn inside-out when tampered with, it is envisaged that all of the annular groove 28 can be omitted so that the teeth project directly from the wall 18 into the socket 14 It will be noted that the substantially planar teeth 26 and the tube, or the above-mentioned alternative of just the teeth, constitute a latching throat according to the present invention.

In use, the latching throat snaps into a "locking" position in which its free end, which is of uniform thickness as well as being of triangular outline when viewed axially (see Figure 1), abuts a shoulder 30 of the plug 12 It is not possible to insert a slim tool into the socket to flex all of the teeth away from engagement with the shoulder 30 because of the "further" shoulders 25 referred to above Moreover, even if three flats had been cut in the plug 12, before assembly, it would not be possible to rotate the plug to bring those flats into alignment with the triangular outline of the free ends of the teeth to allow release of the plug.

As a further aid to ensuring that the plug is held captive within the socket, a portion 44 of the plug, extending from the shoulder towards the barrel-shaped portion 23 of the plug, is preferably formed to be of triangular outline so that it has a crosssectional area corresponding to the are defined by the free ends of the teeth 26.

Alternatively, however, the triangular portion 44 could be replaced by an otherwise cylindrical portion having an axiallyextending rib projecting therefrom for lying, in use, between a pair of adjacent teeth 26 in the socket 14 Indeed, the triangular portion 44 could be replaced by any one of many different shapes which would function satisfactorily as well as being conveniently injection moulded.

Many of the additional security features disclosed in our British patent no 1 430 093, and its British patent of addition No.

1515298, to which the reader is hereby directed to refer, can be included in the seal described hereinbefore For example, 1 578 024 although the oval form of the co-operating portion at the open end of the socket is preferred because of the ease with which it can be moulded, non-circular outlines such as rectangular or star are possible within this invention Moreover, the strap 10 can be formed with a stop or collar 40, shown in dotted outline in Figure 2, the effect of which is to limit the effective length of the strap without reducing the available printing area.

It is always to be remembered that the primary purpose of the present tamperproof shackle seals is not that they should lock a container by their strength, but that they should be unopenable except by causing visible damage.

Claims

WHAT WE CLAIM IS:-

1 A tamperproof shackle seal which is a one-piece plastics moulding, and comprises a strap, a plug at one end of the strap and a socket at the other end of the strap; the plug having a leading end and a shoulder which faces away from said leading end; the socket having a sleeve-like wall which is closed at one end and has an open mouth at its other end; a resiliently deformable and circumferentially continuous latching throat including at least three symmetrically disposed and substantially planar teeth which converge towards one another in the direction axially away from the mouth, a first end of the latching throat being fixed to the wall and free ends of the teeth presenting a polygonal outline for the latching throat, when viewed axially; a first portion of the socket lying adjacent to the mouth, and a portion of the plug which in use co-operates with that first portion, having substantially similar non-circular internal and external outlines respectively, when viewed axially; and at least a part of said internal outline of the first portion lying radially outwards of an internal outline of an immediately adjacent second portion of the socket to define thereby a further shoulder which faces the mouth; whereby insertion of the plug into the socket causes the teeth of the latching throat to be flexed until they can spring back for their free ends to abut the shoulder and hold the plug captive in the socket, insertion of a tool to occasion subsequent flexing of all the teeth of the latching throat being prevented by the further shouler.

2 A seal according to claim 1, in which the teeth are carried on one end of an axially-extending tube which is separated from the wall of the socket by an annular groove apart from at the other end of the tube which is fixed to the wall of the socket.

3 A seal according to claim 1 or claim 2, in which there are three teeth.

4 A seal according to claim 3 in which the plug includes a portion of triangular outline, which is located between the shoulder and the co-operating portion of the plug, and which has a cross-sectional area corresponding to the area defined by the free ends of the teeth.

A seal according to claim 1 and substantially as hereinbefore described with reference to the accompanying drawings.

For the Applicants:GILL, JENNINGS & EVERY, Chartered Patent Agents, 53 to 64 Chancery Lane, London WC 2 A 1 HN.

Printed for Her Majesty's Stationery Office, by Croydon Printing Company Limited, Croydon, Surrey, 1980.

Published by The Patent Office, 25 Southampton Buildings, London, WC 2 A LAY, from which copies may be obtained.