WO1996005586A1

WO1996005586A1 - Lockable seal

Info

Publication number: WO1996005586A1
Application number: PCT/GB1995/001939
Authority: WO
Inventors: Bernard Edwin Taylor; Frank Henry Arthur
Original assignee: Envopak Group Ltd
Current assignee: Envopak Group Ltd
Priority date: 1994-08-16
Filing date: 1995-08-16
Publication date: 1996-02-22
Anticipated expiration: 1997-02-16
Also published as: GB9416482D0; ZA956841B; AU3228495A; JPH0858783A

Abstract

The invention relates to a lockable seal which comprises a bolt (1) and a housing (2). An end portion of the bolt (1) is inserted by sliding into a passage (5, 6) in the housing (2). A resilient U-shaped locking member (9) is positioned in an inner portion (6) of the passage. The locking member (9) engages with the end portion of the bolt (1) to prevent the bolt from being withdrawn from the passage.

Description

LOCKABLE SEAL

This invention relates to a lockable seal.

Lockable seals are used in particular in connection with the transportation of goods, such as in containers. The container is locked immediately after loading, and may then pass through customs without the need for the container to be opened, provided the seal is seen to be intact. Such seals have both indicative and barrier functions. An indicative seal is one which will immediately indicate to an inspector if an unauthorised attempt has been made to break open the seal. A barrier seal is one which is sufficiently robust and strong to deter unauthorised attempts to force it open.

Conventional lockable seals for use with containers and the like consist of a cylindrical bolt and a housing having a passage therein for slidingly receiving the bolt. Locking means are provided within the passage, such that the end of the bolt can be slid into the passage but is thereafter locked and cannot be withdrawn. The forward portion of the bolt is conically tapered towards the end, and the tapered portion is immediately preceded by a circumferential shoulder. The passage is substantially cylindrical for receiving the bolt, and has a circumferential channel between its ends, the channel holding a resilient split ring locking member. As the bolt is inserted into the passage, the forward taper slidingly cooperates with the split ring so as to gradually enlarge the ring in diameter, this enlargement being accommodated within the circumferential channel. Eventually, the broadest part of the taper will pass the split ring, and the ring will then spring back to a smaller diameter and settle behind the shoulder of the bolt. In this position, the outer diameter of the split ring is still greater than the internal diameter of the passage, but the ring is still accommodated within the circumferential channel. However, on attempted withdrawal of the bolt, the split ring abuts against the side of the circumferential channel and the shoulder of the bolt, and thus prevents such withdrawal. The locked seal can then only be opened by physically destroying it, which is normally done by cutting the bolt with heavy duty cutters.

Although such seals are reasonably secure, it has been possible in some cases to "unlock" them in unauthorised fashion. This can sometimes be done by twisting the bolt and winding it out from the housing. Moreover, such seals are relatively complicated to manufacture and hence expensive.

The present invention provides an alternative form of lockable seal which is simpler in construction than the conventional seal, and hence less expensive to manufacture, whilst retaining acceptable robustness and strength. Moreover, the present seal has improved security, in that the bolt cannot be released by twisting.

The present invention thus provides a lockable seal comprising a bolt and a housing having a passage therein for slidably receiving an end portion of the bolt, the end portion of the bolt being slidably insertable into the passage but not thereafter slidably withdrawable therefrom, the end portion of the bolt being tapered towards the end and the tapered portion being followed by a shoulder, characterised in that the passage has an outer portion and a broader inner portion separated from the outer portion by a step, a resilient U-shaped locking member is present in the inner portion of the passage so as to receive the tapered end of the bolt between the limbs of the U, the limbs of the U being resiliently biased towards each other and each having a step on the inner side of the U facing away from the free end, whereby the tapered end of the bolt is insertable through the outer portion of the passage and into the inner portion, whereupon it passes between the free ends of the U-shaped member, the tapered end of the bolt cooperating with the free ends of the U-shaped member to force them apart until the steps on the limbs of the U engage with the shoulder of the bolt, subsequent withdrawal of the bolt then being prevented by abutment between the free ends of the U- shaped member and the step between the inner and outer portions of the passage.

Preferably the bolt is tapered on opposite sides thereof so that it has two shoulders opposite each other. Each shoulder then can interlock with a respective step on the two limbs of the U-shaped member. The bolt is preferably flat rather than cylindrical, with the tapers and shoulders on opposite edges.

Reference is now made to the accompanying drawings, in which:

Figure 1 is a side view showing a bolt and a housing in longitudinal section according to an embodiment of the invention with the bolt not yet inserted into the housing;

Figure 2 corresponds to Figure 1 but shows partial insertion of the bolt;

Figure 3 corresponds to Figures 1 and 2, and shows complete insertion of the bolt,

Figure 4 corresponds to previous figures and shows the arrangement when an attempt is made to withdraw the bolt;

Figure 5 is a transverse section on the line V-V of Figure 4;

Figure 6 shows an alternative embodiment of seal according to the invention, in the locked position; and

Figure 7 is a transverse section on the line VII-VII of Figure 6. Referring first to Figures 1 to 5, the lockable seal includes a bolt 1 and a housing 2. The bolt 1 is of flat rectangular cross section. Its forward end has a tapered portion 3, of arrow head shape, followed immediately by a pair of shoulders 4. These shoulders 4 present a substantially flat face directed towards the rear of the bolt.

The housing 2 has a passage therein for receiving the bolt 1, the passage having an outer portion 5 and a broader inner portion 6. There is an intermediate portion 7 of the passage and the boundary between the intermediate portion 7 and the outer portion 5 is marked by a pair of flat steps 8. The outer portion 5 of the passage is dimensioned to receive the bolt 1 including the broadest part of the tapered portion 3.

A resilient U-shaped locking member 9 is positioned in the inner portion 6 of the passage. The U-shaped member is, for example, of spring steel and is formed by bending a flat strip through 180°. The two limbs of the U- shaped member are biased towards each other. Each limb is folded back on itself at the end, to create a pair of steps on the respective inner faces of the U, the steps presenting flat faces directed away from the rounded free ends 11 of the U. The side wall of the inner portion 6 of the passage is shaped to form a ridge 12 which, in the initial position shown in Figure 1, maintains the ends of the U-shaped member spaced somewhat apart, but which does not in any way^" obstruct the passage of the bolt as described below.

To effect locking of the seal, the tapered end 3 of the bolt is inserted into the outer portion 5 of the passage, and through into the inner portion 6 until it engages with the free ends of the U-shaped member, as shown in Figure 2. The sloping faces of the tapered portion 3 then cooperate with the free ends of the U- shaped member, so that the free ends of the U-shaped member are resiliently forced apart as the bolt is inserted further into the passage. Once the steps 10 of the U-shaped member have passed the shoulders 4 of the bolt, the folded-back portions at the ends of the U-shaped member snap into the recess defined immediately behind the shoulders 4 of the bolt, as shown in Figure 3. The dimensions of the bolt and the U-shaped member are such that, in this position, the forward end of the bolt meets the rounded bottom of the U-shaped member. Further forward movement of the bolt is prevented by abutment between the bottom of the U-shaped member and the end wall of the internal portion 6 of the passage.

On attempted withdrawal of the bolt 1 from the housing 2, the U-shaped member remains attached to the bolt, and is dragged into the intermediate portion 7 of the passage. The width of the intermediate portion is such that it can just accommodate the bolt with the U- shaped member clipped around it. The rounded ends 11 of the U-shaped member, which project from the recessed portion of the bolt, abut against the steps 8 at the boundary of the intermediate portion 7 and outer portion 5 of the passage. In view of the corresponding abutment between the shoulders 4 of the bolt and the steps 10 of the U-shaped member, the bolt cannot be withdrawn from the housing. In this position, as shown in Figure 4, the side walls of the intermediate portion 7 of the passage prevent the free ends of the U-shaped member from being opened to release the bolt. Thus, even if an attempt were made to interfere with the locked seal by sliding an instrument into the passage along side the bolt, it would still not be possible to force the ends of the U-shaped member out of engagement with the bolt. The bolt 1 is generally made of mild steel although any other suitably strong material could be used. The housing 2 may suitably be made of a strong plastics material, such as ABS. This facilitates manufacture, in that the housing can be made in two halves, the U-shaped member inserted, and then the two halves joined together by ultrasonic welding. The housing can also be made of other suitably strong materials, such as metal.

The embodiment shown in Figures 6 and 7 is similar to that already described, except for a slightly different design of housing. In this embodiment, the housing is manufactured in two parts. There is an inner part 15, which defines the passage as before. This is encased within an outer sheath 16, which also defines the end wall 17 of the passage. At the opposite end, the sheath is formed to provide sloping side walls 18, leaving an opening sufficient to receive the bolt into the passage.

In a modification (not shown) of the embodiment of Figures 6 and 7, the outer casing may be constructed in two parts, consisting of an end wall and a lateral surrounding wall. This may facilitate construction and does not affect the operating of the internal locking components as described above.

The lockable seal described permits a container or similar article to be locked under secure conditions. The seal is sufficiently robust to deter any unauthorised attempt at interference. If any such attempt is made, then this is immediately apparent from the state of the seal. Once it has been locked, the seal can only be opened by physical destruction thereof. This is normally effected by authorised personnel who will use heavy duty cutters to cut the bolt.

ENVO.POSIBOLT

Claims

1. A lockable seal comprising a bolt and a housing having a passage therein for slidably receiving an end portion of the bolt, the end portion of the bolt being slidably insertable into the passage but not thereafter slidably withdrawable therefrom, the end portion of the bolt being tapered towards the end and the tapered portion being followed by a shoulder, characterised in that the passage has an outer portion and a broader inner portion separated from the outer portion by a step, a resilient U-shaped locking member is present in the inner portion of the passage so as to receive the tapered end of the bolt between the limbs of the U, the limbs of the U being resiliently biased towards each other and each having a step on the inner side of the U facing away from the free end, whereby the tapered end of the bolt is insertable through the outer portion of the passage and into the inner portion, whereupon it passes between the free ends of the U-shaped member, the tapered end of the bolt cooperating with the free ends of the U-shaped member to force them apart until the steps on the limbs of the U engage with the shoulder of the bolt, subsequent withdrawal of the bolt then being prevented by abutment between the free ends of the U-shaped member and the step between the inner and outer portions of the passage.

2. A lockable seal according to Claim 1, in which the bolt is tapered on opposite sides thereof so that it has two shoulders opposite each other.

3. A lockable seal according to Claim 2, in which each shoulder is adapted to interlock with a respective step on the two limbs of the U-shaped locking member.

4. A lockable seal according to Claim 2 or 3, in which the bolt is of flat cross section, with the tapers and shoulders on opposite edges.