AU2003264605B2 - Tamper Resistant Lock Bolt - Google Patents

Description

11895AU

ORIGINAL

Complete Specification Applicant: Inovec Pty Ltd Title: Tamper Resistant Lock Bolt Address for Service: LESICAR PERRIN, 49 Wright Street, Adelaide, South Australia 5000, Australia The following statement is a full description of this invention, including the best method of performing it known to me/us: Tamper Resistant Lock Bolt BACKGROUND OF THE INVENTION The present invention relates to an improved strength lock arrangement and in particular to a retractable lock bolt device with enhanced tamper resistance.

Lock bolts traditionally include means for resisting withdrawal of a lock bolt from a door frame when unauthorised force is applied. Such unauthorised force can occur when a jemmy bar or similar device is applied to a lock during forced entry.

Bolts usually contain serrations or grooves designed to bind with a face plate in the door. The grooves must have a tapered lead in and lead out or the serrations must be shallow enough for the lock bolt not to bind during normal operation.

Consequently the resistance they offer when unauthorised force is applied is reduced.

It is an object of the present invention to provide for a lock arrangement that overcomes at least some of the aforementioned problems or provides the public with a useful alternative.

It is a further object of the present invention to provide for a lock arrangement of the type having a tamper resistant lock bolt or tongue that will not bind with the face plate during normal operation.

SUMMARY OF THE INVENTION Therefore in one form of the invention there is proposed a lock bolt for use in a lock arrangement of the type where said bolt is retractable and adapted to extend through a face plate when locked, said bolt including: a top surface, an opposing parallel bottom surface, two side surfaces, a front and a rear surface; and a channel extending across at least one surface of said lock bolt, said channel filled with a insert that in the normal state is flush with said surface.

In preference said insert is constructed of a compressible material.

Preferably said insert includes a collapsible structure.

In preference said insert prevents engagement of said channel with said face plate during normal operation.

Preferably said channel is aligned with a side of said face plate when said bolt is in the locked position.

In preference said insert is compressed and said channel engages with said face plate when pressure is applied to said bolt in a locked position.

Preferably said channel includes a bottom and two longitudinally parallel converging sides.

In preference said insert is retained within said channel.

Preferably said insert is a wedge shaped strip that is slidably inserted into said channel.

In preference said sides of said channel are correspondingly wedge shaped to allow said polymer strip to be held securely.

Preferably said polymer strip is arranged to maintain its shape during normal operation.

In preference said insert is constructed of a composite material.

In a further form of the invention there is proposed a lock bolt for use in a lock arrangement of the type where said bolt is retractable and adapted to extend through a face plate when locked, said bolt including: a top surface, an opposing parallel bottom surface, two side surfaces, a front and a rear surface; a channel extending across at least one surface of said lock bolt; and a layer which covers said channel that in the normal state is flush with said surface.

Preferably said layer which covers said channel is constructed from a thin layer of aluminium.

In preference said layer is compressed and said channel engages with said face plate when pressure is applied to said bolt in a locked position.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an implementation of the invention and, together with the description, serve to explain the advantages and principles of the invention. In the drawings, Figure 1 is an isometric view of a lock bolt and face plate illustrating the present invention; Figure 2 is an isometric view of deformable material of the present invention; Figure 3 is a partial cross sectional view of the bolt of the present invention detailing one embodiment of the deformable material; Figure 4 is a side plan view of the lock bolt of the present invention being forced; and Figure 5 is a cross sectional view of the channel once the deformable material has collapsed illustrating the engagement of the channel wall with the face plate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following detailed description of the invention refers to the accompanying drawings. Although the description includes exemplary embodiments, other embodiments are possible, and changes may be made to the embodiments described without departing from the spirit and scope of the invention. Wherever possible, the same reference numbers will be used throughout the drawings and the following description to refer to the same and like parts.

In one form of the invention and as illustrated in Figure 1 there is proposed a lock bolt 10 for use in a lock arrangement 12 including a top surface 14, an opposing parallel bottom surface 16, two opposing and parallel sides 18 and 20, a front or leading edge 22, and a channel 24 extending across at least one of the surfaces of the bolt 10 containing an insert 26. Typically a channel extends across both of the side surfaces 18 and 20. The insert 26 in the normal state is flush with the surface of the said lock bolt The bolt 10 is retractable and adapted to extend through, or engage a face plate 28 when in a locked position. The face plate 28 contains an aperture 30 of dimensions to allow the bolt 10 to pass therethrough. It should be understood by the reader that the face plate 28 can be of any configuration providing that when the lock bolt 10 is in the locked position the channel 24 is aligned with at least one side of the face plate 28.

The lock arrangement 12 is used in conjunction with a door (not shown) whereby the face plate 28 is securely attached to the door frame. The lock bolt 10 is retractably mounted within the cavity of the door and is supported in a lock case (not shown) as is known in the art.

As illustrated in Figure 2 the insert 26 has two longitudinally parallel converging sides 32 and 34. Correspondingly, and as illustrated in Figure 3, the channel 24 includes two inwardly tapered walls 36 and 38. The tapered walls 36 and 38 of the channel 24 enable the insert 26 to be securely wedged therein. The surface 40 of the insert 26 in the normal state is flush with the surface 42 of the bolt and therefore any contact between the face plate 28 and the bolt 10 during normal operation results in the two surfaces sliding over one another without resistance.

This is a distinct advantage over conventional bolts that contain serrations or grooves designed to bind with a face plate in the door as these can catch during normal operation. The depth of the channels does not have to be shallow in the present invention to reduce the chances of the bolt binding since it is covered during normal operation.

The insert 26 can take the form of a wedge shaped strip that can be slidably mounted within the channel 24, however, the reader should understand that the insert is not limited to this type of configuration. The insert 26 can be made of a solid material that is compressed or deformed when pressure is applied. The insert may be a collapsible structure such as that illustrated in Figure 3, whereby the structure collapses when pressure is applied. Alternatively, the channel 24 could be covered by a layer of material such as a thin aluminium sheet which prevents the channel 24 engaging with the face plate 28 during normal operation.

It should also be understood that tapering of sides of the insert 26 and the channel 24 to facilitate fastening is only one method of fixing the insert 26 to the lock bolt 10. Any fixing means including adhesive could be used to secure the insert 26 within the channel 24. However as the reader should appreciated an insert 26 configured to slide within a receiving channel 24 of similar dimensions would provide a cost effective and easily replicable option if the material is damaged during tampering.

If unauthorised tampering occurs, as illustrated in Figure 4, and force is applied to the leading edge 22 of the lock bolt 10 as ensues when a lock is jemmied the insert 26 is pressed against the edge of the aperture 30 in the face plate 28 in the direction of arrow 44. This force causes the insert 26 to collapse in the direction of arrow 46. Therefore as the bolt 10 is driven back through the aperture 30 by the pressure applied by the jemmy bar 48 the wall 38 of the channel 24 engages the face plate 28. As further illustrated in Figure 5, when the insert 26 collapses the wall 38 of the channel 24 abuts the face plate 28. The lock bolt 10 is thereby prevented from being driven back through the aperture 30 because of the resistance of the wall 38 against the face plate 28.

As the reader can now appreciate the depth of the channel 24 is not limited as in conventional bolts since the channel 24 is covered during normal operation.

Only when force is applied such as occurs during forced entry, can one of the walls of the channel 24 engage the face plate 28. This therefore means that the channel 24 can be a suitable depth to increase the strength of the locking apparatus 12 against unauthorised force.

Further advantages and improvements may very well be made to the present invention without deviating from its scope. Although the invention has been shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope and spirit of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus.

In any claims that follow and in the summary of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprising" is used in the sense of "including", i.e. the features specified may be associated with further features in various embodiments of the invention.

Dated this Thursday, November 27, 2003 Inovec Pty Ltd By his Patent Attorneys LESICAR PERRIN

Claims (18)

1. A lock bolt for use in a lock arrangement of the type where said bolt is retractable and adapted to extend through a face plate when locked, said bolt including: a top surface, an opposing parallel bottom surface, two side surfaces, a front and a rear surface; and a channel extending across at least one surface of said lock bolt, said channel filled with a insert that in the normal state is flush with said surface.

2. A lock bolt as in claim 1 wherein said insert is constructed of a compressible material.

3. A lock bolt as in claim 1 wherein said insert includes a collapsible structure.

4. A lock bolt as in claim 1 wherein said insert prevents engagement of said channel with said face plate during normal operation.

A lock bolt as in claim 1 wherein said channel is aligned with a side of said face plate when said bolt is in the locked position.

6. A lock bolt as in claim 1 wherein said insert is compressed and said channel engages with said face plate when pressure is applied to said bolt in a locked position.

7. A lock bolt as in claim 1 wherein said channel includes a bottom and two longitudinally parallel converging sides.

8. A lock bolt as in claim 1 wherein said insert is retained within said channel.

9. A lock bolt as in claim 1 wherein said insert is a wedge shaped strip that is slidably inserted into said channel.

A lock bolt as in claim 1 wherein said sides of said channel are correspondingly wedge shaped to allow said polymer strip to be held securely.

11. A lock bolt as in claim 1 wherein said polymer strip is arranged to maintain its shape during normal operation.

12. A lock bolt as in claim 1 wherein said insert is constructed of a composite material.

13. A lock bolt for use in a lock arrangement of the type where said bolt is retractable and adapted to extend through a face plate when locked, said bolt including: a top surface, an opposing parallel bottom surface, two side surfaces, a front and a rear surface; a channel extending across at least one surface of said lock bolt; and a layer which covers said channel layer that in the normal state is flush with said surface.

14. A lock bolt as in claim 13 wherein said layer is collapsible.

A lock bolt as in claim 14 wherein said layer which covers said channel is constructed from a thin layer of aluminium.

16. A lock bolt as in claim 13 whereby said channel engages with said face plate when pressure is applied to said bolt in a locked position.

17. An apparatus substantially as herein before described and claimed and as illustrated in Figures 1, 2, 4 and

18. An apparatus substantially as herein before described and claimed and as illustrated in Figure 3.