GB2296029A - Padlock with lock unit retained by chamfered plate held in dovetail joint - Google Patents

Abstract

A padlock includes a hardened steel retaining plate 38 with a chamfered peripheral edge which rests on an internal abutment shoulder 40 in a recess 20 and overlies a lock unit 24. The peripheral edge of the recess 20 is forged or deformed to create a lip 42 which securely holds the retaining plate against the shoulder 40, thus defining a dovetail joint. The padlock can be used conventionally or with a fitting 80 comprising a stud 84 with an enlarged head 86 attached to a plate 82, and a second plate 90 having a circular aperture 92 which can be passed over the stud 84. A groove 68, between the studs 58 and 60 of the fastening member 50 of the padlock, passes over the stud 84 when the lock is open. When locked, a curved area at the top of the groove 68 engages against the enlarged head 86 and prevents the lock from being removed. Hence the two plates 82, 90 are locked together. <IMAGE>

Description

LOCK ASSEMBLY This invention relates to a lock assembly and is more particularly concerned with a padlock assembly.

A padlock assembly is known which comprises a lock body; a fastening member in the form of a shackle which is moveable relative to the lock body between a relatively closed position and a relatively open position, and a lock mounted in the lock body and operatively connected with the fastening member for locking the fastener in said relatively closed position. The lock normally comprises a key-operated lock unit which is mounted in a recess extending into the lock body from a surface thereof.

With such an arrangement, a retaining plate having a slot therethrough to receive the key, is disposed so as to overlie the lock unit, and means are provided for securing the retaining plate in position. Such securing means may take the form of rivets or the like which serve to secure the retaining plate to the lock body. However, the use of rivets is undesirable because, if the heads of the rivets are cut away or drilled out, the retaining plate can be removed, thereby enabling the lock unit to be removed and the padlock assembly opened. In another design, the retaining plate is held in position by means of one or more retaining screws which are disposed in shacklereceiving recesses in the lock body. Whilst this design is more secure than the first-mentioned design, it places certain restrictions on the internal design of the lock body.

It is therefore an object of a first aspect of the present invention to provide a lock assembly having an improved means for securing the retaining plate in position.

According to said first aspect of the present invention, there is provided a lock assembly comprising a lock body; a fastening member mounted in the body; a key-operable lock unit which is mounted in a recess extending into the lock body from a surface thereof and which is operatively connected with the lock unit; a retaining plate overlying the lock unit; and means securing the retaining plate to the lock body, wherein the retaining plate has a peripheral edge which is at least partly chamfered so as to flare outwardly away from the surface of the lock body in which the recess is provided, and the securing means comprises a portion of the lock body which (a) defines at least part of the wall of the recess lies against such chamfered peripheral edge.

In this manner, a dovetail joint is defined between the lock body and the retaining plate so that the latter is securely held within the recess and is very resistant to even the most determined attack. This dovetail joint is most preferably provided around substantially the whole of the periphery of the retaining plate.

This type of joint can most advantageously be formed by assembling the retaining plate into the recess (which preferably has a parallel-sided peripheral edge at this stage), and then subjecting the surface of the lock body around the recess to a localised forging or other deforming operation which causes part of the material of the lock body to flow inwardly of the recess so as to cause the peripheral edge of the recess to adopt a correspondingly chamfered form to that of the peripheral edge of the retaining plate so that the plate is firmly clinched in place.

Accordingly, the present invention further resides in a method of manufacturing the lock assembly in which said localised forging or other deforming operation is effected to secure the retaining plate in the recess in the lock body.

Surprisingly, it has been found that this operation can be effected successfully on a previously hardened steel lock body, although the present invention is applicable to lock bodies formed of any other suitable material, eg brass or unhardened steel. Such operation may even be effected on lock bodies which have already been zinc-plated for corrosion resistance without unduly affecting the corrosion-resistance since the very localised deformation operation required to form the joint is insufficient to destroy the integrity of the zinc plating in view of the ductility of the latter.

Preferably, the retaining plate is disposed in the recess so that it is spaced inwardly of the surface of the lock body in which the recess is provided, and the securing means further comprises a lip which is defined by a portion of the lock body and which overlaps part of the retaining plate so as to trap the latter in the recess. Such a lip can be formed during the aforesaid localised forging or other deforming operations.

In a preferred arrangement, the retaining plate is engaged against an abutment shoulder within the recess, said abutment shoulder being defined by part of the lock body.

Preferably also, the extends substantially completely around the recess.

Such a way of securing the retaining plate in the recess is relatively simple to execute and does not require any additional fixing means such as screws, rivets or the like.

In known padlock assemblies of the type wherein the fastening member takes the form of a U-shaped shackle which projects from the lock body, it is common practice to use such a padlock for securing fittings known as hasp and staple fittings or hasp and padbar. Such fittings are used for securing two parts together, such as a door to a door frame, a window to a window frame or a lid to a box. The staple is secured so as to project from one of the parts, whilst the hasp or padbar is secured to the other of the parts and is pivotable between a position in which it lies clear of the staple and a position in which the staple projects through an opening in the hasp or pad bar. The U-shaped shackle of the padlock can be passed through the eye of the staple in order to prevent the hasp or padbar from being detached therefrom.However, such a fitting is relatively exposed to attack by a jemmy, saw or bolt croppers. In order to make the padlock more secure, it is known to extend the sides of the lock body upwardly so as to enclose most, and in some cases all, of the shackle when the latter is in the locked position, there being a groove provided in the lock body for receiving the staple. This makes the padlock rather more resistant to attack. However, it is still possible to attack the padlock by forcibly rotating it relative to the staple so that the latter becomes fractured. In order to mitigate this problem, it is known also to provide a staple which is capable of rotation relative to the hasp or padbar. However, it is still possible to attack the padlock using a jemmy or crowbar inserted between the lock body and the part to which the staple is secured.

It is therefore an object of a second aspect of the present invention to provide a lock assembly and combination of lock assembly with staple and hasp or padbar which can provide additional security against attack.

According to said second aspect of the present invention, there is provided a lock assembly comprising a lock body; a fastening member moveable relative to the body between a relatively closed position and a relatively open position; and a lock which is mounted in the lock body and which is operatively connected with the fastening member for locking the fastening member in said relatively closed position, wherein the fastening member has an undercut groove for receiving an undercut element of a fitting to be secured by the lock assembly, the undercut groove opening on to an external surface of the fastening member and having an end extending to an adjacent external surface of the fastening member, said adjacent external surface facing the lock body so that, in said relatively closed position, the lock body cooperates with said adjacent external surface of the fastening member to prevent disengagement of the undercut element from said end of the undercut groove and so that, in said relatively open position, the lock body is spaced from said one end of the groove so as to enable the undercut element to be engaged/disengaged from the undercut groove.

With such a design of lock assembly, not only can the undercut element be completely concealed with the lock assembly, but also there is no need to provide an aperture (such as that provided in a staple) in the undercut element for receiving the fastening member of the lock assembly. Additionally, such a design can be executed in a way which permits free rotation of the lock assembly relative to the undercut element when the latter is retained in the lock assembly with the fastening member in its relatively closed position.

Also in accordance with said second aspect of the present invention, there is provided a lock assembly according to said second aspect of the present invention in combination with a fitting comprising said undercut element and a hasp, padbar or the like having an aperture through which the undercut element passes.

Preferably, the hasp, padbar or the like is of a size such that the lock assembly, when engaged with the undercut element, lies wholly within the area of the hasp, padbar or the like irrespective of the rotary position of the lock assembly relative to the undercut element.

The lock assembly according to said first aspect of the present invention may include the features of the lock assembly according to said second aspect of the present invention or it may have a fastening member in the form of a U-shaped shackle which can be engaged in a conventional way through an eye in a staple or through a link in a chain etc.

An embodiment of both aspects of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig 1 is an axial section through a padlock assembly according to said first and second aspects of the present invention, said section being taken on the line 1-1 of Fig 2, Fig 2 is an axial section taken on the line 2-2 of Fig 1, Fig 3 is an underneath plan view of the padlock assembly of Figs 1 and 2, and Fig 4 is a section through a fitting designed to be used with the padlock assembly of Figs 1 to 3.

Referring now to Figs 1 to 3, the padlock assembly comprises a lock body 10 which is machined from a suitable solid material such as steel or brass. If the lock body is machined from steel, it may then be subjected to a hardening heat-treatment. The lock body 10 has upper and lower ends 12 and 14, respectively. Mutually parallel spaced bores 16 and 18 extend into the lock body 10 from the upper end 12. The bore 16 extends almost completely to the lower end 14, whilst the bore 18 extends for only approximately one third of the depth of the lock body 10. The lock body 10 is also formed with a large recess 20 which extends from the lower end 14 between the bores 16 and 18. The lock body 10 is also provided with a cross-bore 22 which intersects the bore 16 and the recess 20 at right angles so as to open into the bore 18.

A conventional key-operated pin tumbler lock unit 24 is disposed within the recess 20 and has a rotary operating element 26 which is operatively engaged with a rotary cam 28 mounted in a region of the recess 20 which is in alignment with the cross-bore 22. The rotary cam 28 coacts with a pair of balls 30 and 32 which are disposed within the cross-bore 22 and which are respectively associated with the bores 16 and 18. The lock unit 24 also includes a hardened steel rotor plate 34 having a slot 36 therethrough of a size and profile to fit the key (not shown) for operating the lock unit 24. The recess 20 is closed at the lower end 14 of the lock body 10 by means of a hardened steel retaining plate 38 which rests on an internal peripheral abutment shoulder 40 formed in the lock body 10.

As can be seen from Fig 3, the retaining plate 38 is of race-course shape in plan view and the recess 20 at its end which opens onto the lower ends 12 of the body 10 is of similar shape. The retaining plate 38 fits wholly within the open end of the recess 20 so that it is spaced inwardly of the lower end 14 of the lock body 10. As can be seen from Figs. 1 and 2, the peripheral edge of the retaining plate 38 is chamfered so that it flares outwardly away from the lower end 14. For ease of understanding, the degree of chamfering has been exaggerated in the drawings. In its as-machined state, the peripheral edge of the recess 20 around its open end is parallel-sided.After assembling the retaining plate into the recess 20, the lower end 14 of the lock body 10 around the recess 20 is subjected to a localised forging operation which causes part of the material of the lock body 10 to flow inwardly of the recess 20 so as to form a lip 42 which overlaps the edge of the retaining plate 38 and to cause the peripheral edge of the recess 20 to adopt a correspondingly chamfered form to that of the peripheral edge of the retaining plate 38. In this manner, the retaining plate 38 is firmly clinched in place by means of a dovetail joint extending completely around the retaining plate 38. The lip 42 extends completely around the open end of the recess 20. As a result of the flow of material during the localised forging operation, a shallow groove 44 is defined around the lip 42.This way of securing the retaining plate 38 in position is very secure and easy to execute. It is very difficult to attack the lip 42 successfully to enable the retaining plate 38 to be removed without so damaging the latter that it becomes irremovably trapped in the recess 20.

The padlock assembly further comprises a fastening member indicated by arrow 50. The fastening member 50 comprises a cap 52 which is machined out of the same material of construction as the lock body 10.

The cap 52 has a pair of bores 54 and 56 which are machined through the cap 52 from the top to the bottom thereof and which receive respective studs 58 and 60 cooperating with the respective bores 16 and 18 in the lock body 10. Each of the studs 58, 60 is firmly anchored in its respective bore 54, 56 and has a respective transverse groove 62, 64 formed therein at a location which is aligned with the cross-bore 22 when the fastening member 50 is in a closed position (as illustrated in Figs 1 and 2). In such closed position, the lower end of the cap 52 abuts the upper end 12 of the lock body 10. In Fig 1, the rotary cam 28 is illustrated in a rotary position in which it has forced the balls 30 and 32 outwardly so as to engage in the respective grooves 62 and 64 of the studs 58 and 60, thereby retaining the fastening member 50 in its closed position.However, when the correct key is inserted into the lock unit 24 through an aperture 39 in the plate 38 and rotated, the cam 28 is rotated into a position in which it is spaced inwardly of the balls 30 and 32 by a distance sufficient to enable the latter to move inwardly so as to lie clear of the grooves 62 and 64. Thus, lifting of the fastening member 50 enables it to be moved away from the lock body 10 until an enlarged lug 64 on the lower end of the longer stud 58 abuts against the ball 30 to prevent complete detachment of the fastening member 50 from the lock body 10. In this condition, the fastening member 50 is in an open position.

The cap 52 is machined with a large undercut groove 68 therein which lies between the bores 54 and 56. The undercut groove 68 extends inwardly from one of the faces 70 of the cap 52 and extends to the lower end of the cap 50, i.e that end which faces the upper end 12 of the lock body 10. The relatively narrow entry 68a of the undercut groove 68 also extends to said lower end of the cap 52. The upper end of the undercut groove 68 is of semi-circular shape in plan view (as viewed in Fig 1) and is likewise undercut (as can be seen from Fig 2).

The above-described padlock assembly is intended to be used with a fitting 80 as illustrated in Fig 4. The fitting 80 comprises a first plate 82 which is intended to be bolted or otherwise secured to one part to be fastened by the fitting 80. The first plate 82 has a stud 84 firmly secured thereto so as to extend from one surface thereof. The stud 84 is of circular cross-section and is furnished with an enlarged head 86 which is supported by a reduced-diameter shank portion 88.

The fitting 80 further comprises a padbar defined by a second plate 90 which is pivotally secured to a second part (not shown) intended to be secured to the first part (i.e. that to which the first plate 82 is secured).

The second plate 90 has a circular aperture 92 therethrough which is of a size to enable it to be passed over the enlarged head 86 of the stud 84.

The arrangement is such that the diameter of the enlarged head 86 of the stud 84 is marginally less than the width of the main region of the undercut groove 68 as viewed in Fig 1, whilst the diameter of the shank portion 88 of the stud 84 is marginally less than the width of the reduced entry region 68a of the groove 68. Furthermore, the diameter of the enlarged head 86 is such that it can be engaged in the open end of the groove 68 when the fastening member 50 is in its relatively open position. Thus, under these conditions, the stud 84 can slide into the undercut groove 68 until it engages against the semi-circular upper end of the latter. When the fastening member 50 is moved into its closed position as illustrated in Fig 1, the lower end of the cap 52 engages against the upper end 12 of the lock body 10 and thereby firmly retains the stud 84 in position within the groove 68.Operation of the key into a locking position moves the rotary cam 28 so that the balls 30 and 32 are caused to be moved outwardly to engage in the respective grooves 62 and 64 whereby to lock the fastening member 50 in its closed position. In this condition, the lock body 10 and the cap 52 lie very closely against the second plate 90 because the distance d (see Fig 4) between the second plate 90 and the enlarged head 86 is only marginally greater than the depth of the reduced size entry 68a of the undercut groove 68. It will also be appreciated that the lock body 10 together with cap 52 can be rotated freely about the longitudinal axis of the stud 84 when the fastening member 50 is in the locked position.

Furthermore, the size of the first and second plates 82 and 90 in plan view is such that the hole of the lock assembly lies within the profile of the fitting 80 irrespective of its rotary position about the axis of stud 84.

This means that the whole of the padlock assembly lies closely against the second plate 90, thereby making it very difficult to attack the lock by inserting a jemmy, crowbar or the like between the padlock assembly and the second plate 90.

It is also to be appreciated that the aboveclescribed design of lock body with internal lock unit 24 and retaining plate 38 can be used with a conventional U-shaped shackle instead of the fastening element 50 described above. This considerably simplifies the manufacture of both types of padlock assembly.

Claims (11)

1. A lock assembly comprising a lock body; a fastening member mounted in the body; a key-operable lock unit which is mounted in a recess extending into the lock body from a surface thereof and which is operatively connected with the fastening member; a retaining plate overlying the lock unit; and means securing the retaining plate to the lock body, wherein the retaining plate has a peripheral edge which is at least partly chamfered so as to flare outwardly away from the surface of the lock body in which the recess is provided, and the securing means comprises a portion of the lock body which (a) defines at least part of the wall of the recess and (b) lies against such chamfered peripheral edge.

2. A lock assembly as claimed in claim 1, wherein the dovetail joint defined between the lock body and the retaining plate is provided around substantially the whole of the periphery of the retaining plate.

3. A method of manufacturing a lock assembly as claimed in claim 1 or 2, comprising the steps of assembling the retaining plate into the recess, and then subjecting the surface of the lock body around the recess to a localised forging or other deforming operation which causes part of the material of the lock body to flow inwardly of the recess so as to cause the peripheral edge of the recess to adopt a correspondingly chamfered form to that of the peripheral edge of the retaining plate so that the plate is firmly clinched in place.

4. A method as claimed in claim 3 wherein the recess has a parallel-sided peripheral edge at the assembly step.

5. A lock assembly as claimed in claim 1 or 2, wherein the retaining plate is disposed in the recess so that it is spaced inwardly of the surface of the lock body in which the recess is provided, and the securing means further comprises a lip which is defined by a portion of the lock body and which overlaps part of the retaining plate so as to trap the latter in the recess.

6. A lock assembly as claimed in claim 1, 2 or 5, wherein the retaining plate is engaged against an abutment shoulder within the recess, said abutment shoulder being defined by part of the lock body.

7. A lock assembly as claimed in claim 5, wherein the lip extends substantially completely around the recess.

8. A lock assembly comprising a lock body; a fastening member moveable relative to the body between a relatively closed position and a relatively open position; and a lock which is mounted in the lock body and which is operatively connected with the fastening member for locking the fastening member in said relatively closed position, wherein the fastening member has an undercut groove for receiving an undercut element of a fitting to be secured by the lock assembly, the undercut groove opening on to an external surface of the fastening member and having an end extending to an adjacent external surface of the fastening member, said adjacent external surface facing the lock body so that, in said relatively closed position, the lock body cooperates with said adjacent external surface of the fastening member to prevent disengagement of the undercut element from said end of the undercut groove and so that, in said relatively open position, the lock body is spaced from said one end of the groove so as to enable the undercut element to be engaged/disengaged from the undercut groove.

9. A lock assembly as claimed in claim 8, in combination with a fitting comprising said undercut element and a hasp, padbar or the like having an aperture through which the undercut element passes.

10. A combination as claimed in claim 9, wherein the hasp, padbar or the like is of a size such that the lock assembly, when engaged with the undercut element, lies wholly within the area of the hasp, padbar or the like irrespective of the rotary position of the lock assembly relative to the undercut element.

11. A lock assembly as claimed in claim 1 and/or claim 8 substantially as hereinbefore described, with reference to the accompanying drawing.