GB2429748A

GB2429748A - Lock cylinder protection assembly

Info

Publication number: GB2429748A
Application number: GB0617253A
Authority: GB
Inventors: John Clifford Charnley
Original assignee: CINTOR Ltd
Current assignee: CINTOR Ltd
Priority date: 2005-09-06
Filing date: 2006-09-01
Publication date: 2007-03-07
Also published as: GB0617253D0

Abstract

In order to prevent removal of the lock cylinder from a door, either forwardly through a handle plate 22 or rearwardly through a lock casing 16, a shroud. 30 is mounted on the lock cylinder 2. The shroud 30 comprises an aperture that is shaped to receive the lock cylinder 2 throughout its length, and the shroud 30 acts as extra material to increase the dimensions of the lock cylinder 2. The shroud 30 comprises bores 32 formed on each side and adapted to receive a screw 34. In order to fit the shroud 30, the shroud 30 is placed over the lock cylinder 2 and a drill or milling tool is used to drill a small blind hole in the side of the lock cylinder 2. Flat ended screws 34 are then screwed into the holes.

Description

Lock Cylinder Protection Assembly The present invention relates to a lock

cylinder shroud member, and relates particularly, but not exclusively, to a S lock cylinder protection assembly including such a shroud member.

Euro profile lock cylinders are widely used in Europe and elsewhere as efficient pin tumbler mechanisms for door locks.

The Euro profile cylinder is attached to a door by a bolt through a corresponding hole in the side of the cylinder.

Most Euro profile cylinders are produced from extruded brass which has a relatively low tensile strength.

Euro profile cylinders are generally mounted in a handle plate that contains an opening for the Euro profile cylinder.

If the cylinder protrudes outside the front of the handle plate it is highly vulnerable to being broken by means of pulling, twisting or snapping with conventional commercially available tools such as pliers and mole grips. Even if the cylinder is flush or slightly recessed behind the front face of the handle plate, the handle plate is generally hollow and can therefore be deformed to allow access to the front of the Euro profile cylinder. The cylinder generally snaps at the weak point where a threaded hole is formed for a bolt, and broken in two such that it can be removed entirely front the lock casing. Removal of the cylinder from the lock casing permits access to the lock mechanism in the lock casing allowing the lock to be disengaged.

German Utility Model no. GM8027038 desciibes a shroud member for a lock cylinder. The shroud member is mounted to the lock cylinder by driving pointed screws through bores formed in the shroud member to deform the outer casing of the lock cylinder. The points of the screws dig into the outer casing of the lock cylinder and hold the shroud on the lock cylinder by the friction between the pointed ends of the screws and the deformed casing of the lock cylinder.

S The assembly described in GM8027038 suffers from the drawback that the screws only grip the walls of the cylinder using friction. The cylinder can be pulled from the shroud if sufficient force is applied to overcome the friction of the screws. Also, the body of the lock cylinder is deformed by the screws, which can cause a malfunction of the cylinder by deforrning the inner surfaces of the cylinder. This can interfere with the pin tumbler mechanism inside the cylinder.

For example, fitting a pointed screw at the bottom of the lock cylinder could cause the blanking pins that retain the lock mechanism to be forced further into the cylinder body.

Fitting the pointed screws on the side walls of the lock cylinder can cause deformation of the vertical holes that contain the driver pins and springs.

Preferred embodiments of the present invention seek to

overcome the disadvantages of the prior art.

According to an aspect of the present invention, there is provided, a lock cylinder protection assembly comprising: a shroud member adapted to engage a lock cylinder to prevent removal of the lock cylinder from a door, the shroud member comprising a body portion adapted to at least partially surround and be mounted to said lock cylinder and at least one bore to enable the shroud member to be mounted to said lock cylinder; and at least one flat ended screw for mounting in at least one said bore to mount the shroud to the lock cylinder.

By providing a shroud member adapted to engage a lock cylinder to prevent removal of the lock cylinder from a door, and at least one flat ended screw for mounting the shroud to the lock cylinder, this provides the advantage of being able S to mount a shroud to a lock cylinder such that it is particularly hard to remove the shroud from the cylinder by a push or a pull attack. For example, a Euro profile lock cylinder was taken and a shroud was mounted to the cylinder with screws having pointed ends (900 point angle screws) such that the screws deformed the outer surface and bit into the surface of the cylinder to hold the shroud in place. A load was then applied to the end of the cylinder by a Dennison tensile test machine and the force required to separate the shroud from the cylinder was found to be 0.53 tonnes.

Another Euro profile cylinder was taken and blind holes were drilled to a depth of 2mm into the cylinder. A shroud was then mounted to the cylinder with flat ended screws (half dog point screws) which were screwed into the 2mm blind holes.

Again, a load was then applied to the end of the cylinder by a Dennison tensile test machine and the force required to separate the shroud from the cylinder was found to be 1.7 tonnes.

In a preferred embodiment, at least one said flat ended screw is a half dog point screw.

This provides the advantage of facilitating alignment between the end of the screw and the blind hole in which the screw is to be mounted.

The assembly may further comprise a drill bit adapted to drill a blind hole in a lock cylinder.

This provides the advantage of assisting a user of the assembly to prepare the lock cylinder for mounting to the shroud.

According to another embodiment of the present invention, there is provided a lock cylinder protection assembly comprising: a shroud member adapted to engage a lock cylinder to prevent removal of the lock cylinder from a door, the shroud member comprising a' body portion adapted to at least partially surround and be mounted to said lock cylinder and at least one bore to enable the shroud member to be mounted to said lock cylinder; and a drill bit adapted to drill a blind hole in a lock cylinder to enable the shroud member to be mounted to the cylinder by at least one flat ended screw.

By providing a shrod member adapted to engaga a lock cylinder to prevent removal of the lock cylinder from a door, and a drill bit adapted to drill a blind hole in a lock cylinder, this provides the advantage of being able to mount a shroud to a lock cylinder such that it is particularly hard to remove the shroud from the cylinder by a push or a pull attack. For example, a Euro profile lock cylinder was taken and a shroud was mounted to the cylinder with screws having pointed ends (9Q0 point angle screws) such that the screws deformed the outer surface and bit into the surface of the cylinder to hold the shroud in place. A load was then applied to the end of the cylinder by a Dennison tensile test machine and the force required to separate the shroud from the cylinder was found to be 0.53 tonnes.

S Again, a load was then applied to the end of the cylinder by a Dennison tensile test machine and the force required to separate the shroud from the cylinder was found to be 1.7 tonnes.

The assembly may further comprise at least one flat ended screw.

At least one said flat ended screw may be a half dog point screw.

The assembly may further comprise a hex wrench for tightening at least one said screw.

In a preferred embodiment, said shroud member further comprises at least one tapered face adapted to be disposed adjacent a face of said lock cylinder.

This provides the advantage that if an attempt is made to pull the lock cylinder through the handle plate, the tapered face of the shroud member disperses the force applied to the handle plate making it harder to pull out the lock cylinder.

The assembly may further comprise a reinforcing member adapted to abut said tapered face and a handle plate in use to prevent deformation of said handle plate.

-J

This provides the advantage of preventing access to the front of the lock cylinder to help prevent removal thereof.

Said shroud member may further comprise at least one protrusion adapted to abut a portion of a handle and/or lock casing in use.

This provides the advantage of making it harder to pull the lock cylinder from the lock casing.

The assembly may further comprise at least one set screw disposed in said protrusion to contact said lock casing.

According to a further aspect of the present invention, there is provided a lock cylinder comprising at least one blind hole formed therein to enable a shroud member to be mounted to the lock cylinder by a flat ended screw.

This provides the advantage of making it easier for a user to mount a shroud to the lock cylinder with a flat ended screw.

Also, by forming a blind hole in the side of a lock cylinder, this provides the advantage that the shroud can be mounted to the cylinder without interfering with the pin tumbler mechanism of the lock cylinder, since lhe outer casing of the lock cylinder is not deformed inwardly.

According to a further aspect of the present invention, there is provided a method of mounting a shroud member to a lock cylinder, the method comprising forming at least one blind hole in a side of the lock cylinder.

By forming a blind hole in the side of a lock cylinder, this provides the advantage that the shroud can be mounted to the cylinder without interfering with the pin tumbler mechanism of the lock cylinder, since the outer casing of the lock cylinder is not deformed inwardly.

In a preferred embodiment, the method further comprises mounting a shroud member having at least one bore formed therein to the lock cylinder by screwing at least one flat ended screw through the respective bore and into said blind hole.

Preferred embodiments of the invention will now be described, by way of example only, and riot in any limitative sense, with reference to the accompanying drawings in which:- Figure 1 is a perspective view of a Euro profile lock cylinder; Figure 2 is a perspective view of the lock cylinder of Figure 1 with the cylinder cam in the open position; Figure 3 is a perspective view of the lock cylinder of Figure 1 disposed in a handle; Figure 4 is a perspective view of the lock cylinder of Figure 1 disposed in a lock casing; Figure 5 is a partial cross sectional side view of the lock cylinder of Figure 1 disposed in a handle and lock casing assembly with a security shroud and handle reinforcing plate mounted on the lock cylinder; and Figure 6 is a partial cross sectional front view of the lock cylinder and shroud of Figure 5; Figure 7 is a cross section through line Ti-A of Figure 5; Figure 8 is a partial cross sectional front view of a shroud of a second embodiment of the present invention; and Figure 9 is a partial cross sectional side view of a lock cylinder protection assembly of a third embodiment of the present invention.

Referring to Figures 1 and 2, a lock cylinder 2 which may be of the Euro profile cylinder type as will be familiar to persons skilled in the art, comprises a barrel 4 having a keyway 6, the barrel 4 being disposed in a two part cylindrical housing 8. A pin tumbler housing 10 holds a pin tumbler mechanism (not shown) for operating the lock. The lock cylinder 2 is formed from extruded brass as will be familiar to persons skilled in the art. A cylinder cam 12 is operated by rotation of the barrel 4 and is shown in the closed position in Figure 1 and the open position in Figure 2. A threaded bore 14 is disposed at the centre of the pin tumbler housing 10 to enable the lock cylinder 2 to be bolted to a lock casing 16 (Figure 4) . The threaded bore 14 is located at the mid point of the lock cylinder below the recess 18 into which the cylinder cam 12 is mounted. This is the weak point of the lock cylinder and generally when a lock cylinder is deformed by pulling and twisting with pliers or the like, the lock cylinder will snap at this mid point.

Referring to Figure 3, the lock cylinder 2 is generally mounted in a handle plate 22 comprising a handle 24 such that the front face 20 of the lock cylinder 2 is exposed through an aperture 26 formed in the handle plate 22. Ideally the front face 20 of the lock cylinder 2 will be flush with the handle plate 22. One method of gaining unauthorised entry to premises is to break the lock cylinder and remove it through the front of the handle plate 22, which permits access to the lock mechanism allowing it to be disengaged. If the front face 20 of the lock cylinder 2 is disposed slightly forwardly of the handle plate 22 then it becomes easier to grip the lock cylinder to break it by means of pulling, twisting or snapping with commercially available tools such as pliers or mole grips. Even if the front face 20 of the lock cylinder 2 is flush or slightly recessed behind the handle plate 22, handle plates are generally hollow and made of relatively weak material such as aluminium or plastics and therefore can easily be deformed backwardly to enable access to the lock cylinder 2.

Referring to Figure 4, when the lock cylinder 2 is disposed in a door (not shown) the front of the lock cylinder 20 will be received in a handle plate 22 (Figure 3) and the cylinder cam 12 (Figure 1 and 2) will be disposed in a lock casing 6.

The lock cylinder 2 is mounted to the lock casing 16 by a bolt (not shown) through threaded bore 14. The cylinder cam 12 is used to operate a bolt 28 in order to bolt and unbolt a door. It will be understood by persons skLlled in the art that the cylinder cam 12 may be used to operate one or more bolts to lock and unlock a door. Another form of attacking a lock cylinder 2 is to drive the lock cylinder 2 rearwardly through the lock casing 16 in order to remove the lock cylinder 2 to allow access to a building, or pull the lock cylinder 2 foiwardly through handle plate 22 (Fig 3) In order to prevent removal of the lock cylinder from a door, either forwardly through a handle plate 22 or rearwardly through the lock casing 16, a shroud 30 formed from an alloy such as brass or steel is mounted on the lock cylinder 2.

The shroud 30 comprises an aperture that is shaped to receive the lock cylinder 2 throughout its length, and the shroud 30 acts as extra material to increase the dimensions of the lock cylinder 2. The shroud 30 comprises bores 32 formed on each side and adapted to receive screws 34. Preferably, screws 34 are flat ended grub screws and may be half dog point screws.

Half dog point screws facilitate alignment between the end of the screw and the hole in which the screw is to be mounted since the end of the half dog point screw will have a smaller diameter than the hole in which it is to be mounted.

Preferably, the bores are blind holes. In order to fit the shroud 30 on the lock cylinder 2, the shroud 30 is placed over the lock cylinder 2 and a drill or milling tool (not shown) is used to drill a small blind hole in the side of the lock cylinder 2. Preferably, the blind hole is drilled to a maximum depth of 2 mm in order to prevent damage to the pin tumbler mechanism disposed in the pin tumbler housing 10.

Alternatively, the lock cylinder may be manufactured with bores 32 already in place.

It has been found that flat ended grub screws screwed into blind holes provide greater resistance to pulling off of the shroud 30 from the lock cylinder 2 than a screw with a tapered end. For example, a Euro profile lock cylinder was taken and a shroud 30 was mounted to the cylinder with screws having pointed ends (9Q0 point angle screws). No blind holes were drilled into the surface of the cylinder and the 90 point angle screws were screwed such that they deformed the outer surface and bit into the surface of the cylinder to hold the shroud in place. A load was then applied to the end of the cylinder by a Dennison tensile test machine and the force required to separate the shroud from the cylinder was found.to be 0.53 tonnes.

Another Euro profile cylinder was taken and blind holes were drilled to a depth of 2mm into the cylinder. A shroud 30 was then mounted to the cylinder with flat ended screws (half dog point screws), which were screwed into the 2mm blind holes.

Again, a load was then applied to the end of the cylinder by a Dennison tensile test machine and the force requiied Lo separate the shroud from the cylinder was found to be 1.7 tonnes.

It can therefore be seen that drilling blind holes into the shroud and using flat ended screws forms an assembly that requires far more force to separate than an assembly using pointed screws biting into the cylinder alone. This is because when the pointed screws are pulled, the load tends to be taken by their tips which have a small surface area causing the brass body of the cylinder wall to be deformed.

On the other hand, the load taken by the flat ended screws is spread out over a larger area making the assembly with flat ended screws and blind holes more resilient to attack.

The shroud 30 further comprises a tapered face 36. The function of the tapered face 36 is to disperse a pulling force outwardly to make it harder to pull the shroud 30 through a handle plate 22.

As mentioned above, some handle plates 22 may be hollow and therefore vulnerable to being deformed inwardly to provide access to the lock cylinder 2. In this case, a reinforcement plate 38 which has an aperture designed to receive the lock cylinder 2 is placed between the handle plate 22 and the shroud 30. The reinforcement plate 38 prevents deformation of the handle plate 22. The reinforcement plate 38 is preferably formed from steel, and has a tapered portion 44 adapted to abut the tapered face 36 of the shroud 30 to disperse pulling forces.

A protrusion 40 is formed integrally with the shroud 30 and * is adapted to abut the lock casing 16 to help prevent forcing the lock cylinder 2 rearwardly through the lock casing 16 by virtue of abutment of protrusion 40 against the lock casing 16. A drilled and tapped hole 42 may be formed in the (I protrusion 40 into which a set screw (not shown) is disposed to contact lock casing 16. The set screw (not shown) also makes it more difficult to deform handle plate 22 to provide access to the lock cylinder 2. Alternatively, packing shims (not shown) could be used instead of a set screw between the shroud 2 and the lock casing 16.

A shroud 130 of a second embodiment of the invention is shown in Figure 8, with parts common to the embodiment of Figures 5 to 7 shown with like reference numerals but increased by 100.

Referring to Figure 8, shroud 130 comprises four bores 132, two formed on either side of the shroud 130. A method of fitting shroud 130 is to drill at least one blind hole in lock cylinder 2, locate the shroud 130 over the blind hole and then screw the shroud 130 to the lock cylinder 2 with a flat ended grub screw. If the blind hole is drilled in the wrong place such that the blind hole and one of the bores 132 do not line up, then by providing two bores 132 on either side of the shroud 130 a second hole can be drilled to line up with the second bore so that the shroud 130 can still be fitted to the lock cylinder 2, without having to replace either the shroud 130 or the lock cylinder 2. Alternatively, the shroud 130 may be manufactured with the bores 132 already in place.

A lock cylinder protection assembly of a third embodiment of the invention is shown in Figure 9, with parts common to the embodiments of Figures 1 to 7 shown with like reference numerals but increased by 200.

Referring to Figure 9, a door 246 comprises front and rear handle plates 222a and 222b in which a lock cylinder 202 and a lock casing 216 are fitted. A first shroud 230a is mounted on the lock cylinder 202 by means of at least one flat ended grub screw (not shown) disposed in at least one bore 232a on either side of the shroud 230a. The first shroud 230a abuts a rear face of the front handle plate 222a to prevent removal of the lock cylinder 202 through the front handle plate 222a.

A second shroud 230b is mounted on the lock cylinder 202 by means of at least one flat ended grub screw (not shown) disposed in at least one bore 232b on either side of the shroud 230b. The second shroud 230b abuts the lock casing 216 to prevent removal of the lock cylinder 202 through the lock casing 216.

As a result of having two shrouds 230a and 230b, if one shroud is broken off, then the other shroud remains in place to prevent removal of the lock cylinder 202. Also, the amount of grub screws holding the shrouds to the lock cylinder is increased, and the force needed to remove the lock cylinder 202 is therefore also increased.

A kit of parts may be provided to upgrade existing lcck cylinders. The kit of parts may comprise a shroud 30, flat ended screws 34, a drill bit (not shown) for forming a 2mm blind hole and a hex wrench (not shown) for tightening the flat ended screws. Alternatively, kits comprising any combination of the above items may he provided.

It will be appreciated by persons skilled in the art that the above embodiments have been described by way of example only and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the invention as defined by the appended claims. In particular, it will be appreciated that the shroud 30 can be retrospectively fitted to existing lock installations, or fitted as new lock assemblies are manufactured. Lock cyliners may also be manufactured with pre-formed blind holes. Also, the shroud described is not restricted to use with Euro profile cylinders, and may be used with other types of lock cylinder. The shrouds described completely surround the lock cylinder, although other shroud shapes may be used that only partially surround the cylinder.

Claims

CLMMS

1. A lock cylinder protection assembly comprising: a shroud member adapted to engage a lock cylinder to prevent removal of the lock cylinder from a door, the shroud member comprising a body portion adapted to at least partially surround and be mounted to said lock cylinder and at least one bore to enable the shroud member to be mounted to said lock cylinder; and at least one flat ended screw for mounting in at least one said bore to mount the shroud to the lock cylinder.

2. An assembly according to claim 1, wherein at least one said flat ended screw is a half dog point screw.

3. An assembly according to claim 1 or 2, further comprising a drill bit adapted to drill a blind hole in a lock cylinder.

4. A lock cylinder protection assembly comprising: a shroud member adapted to engage a lock cylinder to prevent removal of the lock cylinder from a door, the shroud member comprising a body portion adapted to at least partially surround and be mounted to said lock cylinder and at least one bore to enable the shroud member to be mounted to said lock cylinder; and a dril*l bit adapted to drill a blind hole in a lock cylinder to enable the shroud member to be mounted to the cylinder by at least one flat ended screw.

5. An assembly according to claim 4, further comprising at least one flat ended screw.

6. An assembly according to claim 5, wherein at least one said flat ended screw is a half dog point screw.

7. An assembly according to any one of the preceding claims, further comprising a hex wrench for tightening at least one said screw.

B. An assembly according to any one of the preceding claims, wherein said shroud member further comprises at least one tapered face adapted to be disposed adjacent a face of said lock cylinder.

9. An assembly according to claim 8, further corrtprising a reinforcing member adapted to abut said tapered face and a handle plate in use to prevent deformation of said handle plate.

10. An assembly according to any one of the preceding claims, wherein said shroud member further comprises at least one protrusion adapted to abut a portion of a handle and/or lock casing in use.

11. An assembly according to claim 101 further comprising at least one set screw disposed in said protrusion to contact said lock casing.

12. An assembly substantially as hereinbefore described with reference to the accompanying drawings.

13. A lock cylinder comprising at least one blind hole formed therein to enable a shroud member to be mounted to the lock cylinder by a flat ended screw.

14. A lock cylinder substantially as hereinbefore described with reference to the accompanying drawings.

15. A method of mounting a shroud member to a lock cylinder, the method comprising forming at least one blind hole in a side of the lock cylinder.

16. A method according to claim 15, further comprising mounting a shroud member having at least one bore formed therein to the lock cylinder by screwing at least one flat ended screw through the respective bore and into said blind hole.

17. A method of mounting a shroud member to a lock cylinder substantially as hereinbefore described with reference to the accompanying drawings.