GB2431692A

GB2431692A - Drawer locking

Info

Publication number: GB2431692A
Application number: GB0621233A
Authority: GB
Inventors: Terry Ronald Hunt
Original assignee: METAL OFFICE EQUIPMENT Ltd
Current assignee: METAL OFFICE EQUIPMENT Ltd
Priority date: 2005-10-25
Filing date: 2006-10-25
Publication date: 2007-05-02
Anticipated expiration: 2026-10-25
Also published as: GB2431692B; GB0621233D0; GB0521695D0

Abstract

A drawer locking system for a drawer assembly utilises an elongate lock bar 22 moulded from a plastics material and having a plurality of bosses 23 on one side thereof for engagement in slots 21 of a drawer assembly 10 whereby the lock bar 22 may slide vertically parallel to a side panel 12 of the assembly. Opposed to each boss 23 is a respective arm 24 and each drawer 17 has a stop member 32 engageable with a respective arm 24 when the lock member 22 is in a locked position thereby to prevent opening of the drawer. Sufficient strength for the arms 24 can be obtained despite the lock bar being moulded from a plastics material by the engagement between the opposed bosses 23 and the slots 21. For interlocking purposes each drawer can be provided with a cam which, when a drawer is opened, moves the lock bar to its locked position so as to prevent the other drawers from being opened.

Description

DRAWER LOCKING

This invention relates to a locking system for the drawers of a drawer assembly including a plurality of drawers and a side plate adjacent the drawers, and to a drawer assembly incorporating a locking system.

It is known to provide an assembly of drawers with a locking arrangement, either to prevent opening of any of the drawers or to prevent the opening of a closed drawer when one drawer has been opened -anti-tilt mechanism. Such locking arrangements are widely used with office furniture such as filing cabinets, so-called desk pedestals with drawers and free-standing drawer pedestals, which are often provided with wheels. An anti-tilt mechanism may be required on a free-standing office drawer assembly for health and safety reasons, so that the opening of only one drawer at a time is permitted.

A widely used locking arrangement of the kind described above has a lock bar mounted to a side plate (such as a side panel or a frame member) of the drawer assembly, for vertical sliding movement along the length of the bar and parallel to the side plate, between free and locked positions. Usually, the lock bar is slidably connected to the side plate at or adjacent the two ends of the bar. The lock bar has, for each drawer, a respective arm which projects laterally from one side of the bar. The arms obstruct opening of the drawers when the bar is in its locked position, but when the bar is in its free position, the drawers may be opened. A key-operated lock mechanism may be provided to slide the lock bar between its locked and free positions, the lock mechanism usually being mounted on a drawer front or on a facia of the drawer assembly.

Further, if a safety interlock is required, each drawer may have a camming profile arranged to slide the lock bar from its free position to its locked position as the drawer is opened, so that the opening of one drawer locks the other drawers against opening.

The lock bar must have sufficient strength to resist the forces to which it may be subjected in use, by someone attempting to open a second drawer when one is already opened, or deliberately trying to force the mechanism should it have been locked with the key mechanism. Pulling on a drawer will exert a force to the arm associated with that drawer which force will apply a turning moment to the lock bar about its length, in turn tending to twist the lock bar away from the side plate on which it is slidably mounted. The lock bar must thus be able to withstand torque and also requires secure slidable connections to the side plate. Further, the arms must be rigidly connected to the bar. To meet these criteria, lock bars are conventionally made of metal and so require several manufacturing steps, leading to considerable expense.

This invention aims at improving the known form of locking system as described above for the drawers of a drawer assembly, by allowing the manufacture of a lock bar which itself has a reduced strength but which nevertheless still has the required functionality, of effectively locking the drawers of the assembly.

According to this invention there is provided a drawer locking system for a drawer assembly including a plurality drawers and a side panel adjacent the drawers, which locking system comprises: -a multiplicity of slots provided in the side panel, there being a respective slot associated with each drawer; -an elongate lock bar having a plurality of bosses on one side thereof, the bosses being engaged in the slots for sliding movement of the lock bar parallel to the side panel between free and locked positions, there being means to retain the bosses engaged with the slots; -a plurality of spaced arms projecting from the other side of the lock bar each substantially opposed to a boss on said one side of the bar, there being a respective arm and boss for each drawer of the drawer assembly; and -a stop member on each drawer engageable with a respective arm when the drawer is closed and the lock bar is in its locked position so as to prevent opening of the drawer, but which stop member may freely pass the arm when the lock bar is in its free position, to allow opening of the drawer.

With the locking system of this invention, immediately in association with each drawer there is provided a slot for mounting the lock bar, the lock bar having a boss slidably engaged with the slot. By having a drawer locking arm projecting from the other side of the bar directly or substantially opposed to the boss associated with the drawer, the arm, boss and slot are able directly to take the force of an attempt to open the drawer when the lock bar is in its locked position. In this way, the bar does not have to withstand a turning moment along its length and so is not significantly stressed between the spaced pairs of arms and bosses. As such the bar does not need to have great strength between the spaced pairs of arms and bosses.

A consequence of the strength requirement of the lock bar used in the drawer locking system of this invention is that the lock bar may be made of a plastics material, rather than metal. The lock bar may thus comprise a relatively simple one-piece plastics material moulding comprising a strip able to take tensile and compressive loads to permit the bar to be slid between its free and locked positions, and having opposed pairs of bosses and arms to each side thereof, at the required spacing for the drawers of the drawer assembly. Such a moulding may be relatively cheap to produce as compared to the cost of manufacturing a conventional metal lock bar fabricated from individual components connected together for example by welding.

A further advantage of the locking system of this invention is that the lock bar for the locking system may be made longer than may be required for any one drawer assembly. The lock bar may then be cut to the required length for a particular cabinet, so optimising the manufacture of the lock bars by obviating the need to provide different bars for a range of drawer assemblies -for example, one length of bar may be provided for two, three and four drawer filing cabinets, the bar then simply being cut to the required length when a cabinet is being assembled. A further lock bar may be provided for desk pedestals and mobile pedestals, and when used for the latter, the bar is simply cut to a shorter length.

The side panel may be in the form of a plate comprising a metal frame member including spaced slots with one slot directly associated with each drawer, respectively. For the case of a wooden assembly (which term is used herein to mean an assembly of solid wood or of wood-derived products such as chipboard and MDF), the side panel may be in the form of a wooden panel having the slots preferably defined by inserts let into recesses in the slide panel, or by a separate vertically extending plate for example of metal or of plastics and secured to the side panel.

Each slot advantageously is enlarged at one end, and preferably the upper end, so as to facilitate the connection thereto of a boss of the lock bar.

For example, each slot may be of key-hole shape whereby a boss may be entered into the enlarged upper end of the slot and then lowered so as slidably to engage with the narrower part of the slot. To this end, each boss preferably has a first portion adjacent the lock bar and which has a width slightly less than the width of the narrower part of the slot whereby the first portion of the boss may slide along the length of the slot, and an enlarged head the shape of which may fit through the upper part of the slot so as thereby to permit the first portion to be engaged with the narrower part of the slot.

The lock bar may be provided with a region of increased thickness, where the boss and arm of each pair connect to the bar. Such a region preferably presents a flat bearing surface to the side panel in which is defined the slot engaged by the boss. The region of increased thickness may serve to increase the bearing surface of the lock bar with the side panel and so minimise the force to which the arm itself is subjected, should the lock bar be in its locked position and an attempt be made to open a drawer.

As mentioned above, each arm projects from the lock bar from said other side thereof, directly or substantially opposed to a boss associated with a drawer. In this way, force applied to an arm on attempting to open a drawer when the lock bar is in its locked position will directly be transferred to the opposed boss and be resisted by the interengagement thereof with the slot, assisted by the flat bearing surface of the region of increased thickness pressing on the side panel.

Each arm preferably is of a rounded cross-sectional profile and projects from the lock bar by a sufficient distance for inter-engagement with a stop member on a respective drawer. The arrangement of such an arm together with the stop member on a drawer may be essentially conventional, whereby the lock bar when in its locked position resists opening of a drawer but when in its free position permits opening of any selected drawer. The stop member itself may be resilient and include a ramp face for co-operation with the arm of the lock bar, should the lock bar be moved to its locked position when a drawer is open. In this way, the drawer may still be closed by resilient deformation of the stop member, but when closed, the drawer will be locked in that position.

The locking system may be provided with a key-operated lock mechanism mounted on a part of the drawer assembly, such as on a drawer front or on a facia panel above or to one side of the drawers. Typically, a rotary lock mechanism is employed with an eccentric peg projecting from the lock barrel, which peg engages with the lock bar so that operation of the lock mechanism moves the lock bar between its free and locked positions.

In addition to the key-operated lock mechanism, or instead of that lock mechanism, the locking system may be configured as an anti-tilt mechanism.

For this purpose, each drawer should have a camming profile which serves to move the lock bar to its locked setting on opening a drawer, so as thereafter to resist opening of any of the other drawers. Then, on closing the open drawer, the camming profile serves to move the lock bar back to its free position, thereafter permitting either re-opening of the just-closed drawer or opening of any other drawer. For this purpose, the lock bar preferably includes restraining means serving to keep the lock bar either in its free position or in its locked position.

This invention extends to a drawer assembly whenever incorporating a locking system of this invention as described above.

By way of example only, one specific embodiment of drawer locking system for a drawer assembly of this invention will now be described in detail, reference being made to the accompanying drawings in which:-Figure 1 illustrates the carcass of a metal drawer cabinet with one drawer frame fitted thereto; Figure 2 is an enlarged detail view on part A shown in Figure 1 and showing the interengagement of a boss of a lock bar with a slot of the cabinet; Figure 3 is an isometric view of one design of lock bar for use with the cabinet of Figure 1; Figure 4 is an enlarged detail view on part B shown in Figure 3; Figure 5 illustrates the inter-connection of the lock bar with a key-hole slot in a side plate of the cabinet; Figure 6 shows the arm of the lock bar associated with a drawer stop of a drawer; Figure 7 is a detailed view on an enlarged scale, showing the drawer stop used in this embodiment; Figure 8 diagrammatically illustrates a camming profile for use with a drawer, when the locking system is configured as an anti-tilt mechanism; Figure 9 is an enlarged view of part of a modified form of lock bar to replace that shown in Figure 3; and Figure 10 is a side view of the lower part of the modified form of lock bar shown in Figure 9.

Referring initially to Figure 1, there is shown a metal carcass 10 for assembly of drawers suitable for use in an office. The carcass comprises opposed side walls 11,12 a back plane 13 and a base 14. The carcass may be fitted with a top plate (not shown) or may be left open if the carcass is to be mounted for example to the underside of a desk. The carcass is provided internally with side plates 15 extending vertically adjacent the front of the carcass and a reinforcing cross member 16 extends between the upper ends of the two side plates.

In Figure 1, only one drawer 17 is shown, but without its drawer front which will include a handle for opening the drawer. Runners (not shown) of a conventional design are provided between the drawer sides 18 and the side plates 15, the side plates including apertures 19 for the fitting of the runners thereto. Though not shown in Figure 1, carcass rear supports for the runners may also be provided, for example by way of upright members extending within the carcass, against the side walls 11,12.

The side plates 15 are also provided with a plurality of key-hole shaped slots 21, spaced vertically and disposed so that there is one slot immediately adjacent the intended position of each drawer to be fitted to the carcass. In order that the side plates 15 may be used with carcasses having different drawer configurations, more key-hole slots 21 may be provided than are needed for the drawers to be fitted to the carcass, so long as there is a respective slot 21 directly associated with each drawer fitted to the carcass. Each key-hole slot has an upper part of a rounded profile and a lower part of a narrower width than the diameter of the rounded part.

As best seen in Figures 2, 5 and 6, a lock bar 22 is slidably engaged with the slots 21 in the side plates in order to provide the locking function required for the drawers of the finished assembly. The design of lock bar shown in Figure 3 has a plurality of pairs of bosses 23 and arms 24, the pairs being spaced by the separation of the drawers and being disposed on the bar such that the boss 23 of each pair may engage with a respective key-hole slot 21 in the side plate. The bar, at the location of each pair, has an enlargement 25 of increased thickness and which presents a flat surface 26 for bearing against a side plate 15. Projecting from that flat surface is the boss 23, this having a first portion 27 adjacent the flat surface 26 and an enlarged head 28 spaced from the flat surface 26. In this way, a pair of grooves 29 is formed between the flat surface 26 and the enlarged head 28, in which the thickness of the side plate may be accommodated. The distance between the bases of the grooves is slightly smaller than the width of the lower part of the slot 21, so that the boss 23 may freely slide in the lower part of the slot. The profile of the enlarged head 28 is such that it may pass through the upper part of the key-hole slot, thus permitting easy engagement and disengagement of the boss from the slot, through said upper part of the slot.

Essentially directly opposed to each enlargement 25 and boss 23 and projecting from the opposite side of the lock bar 22 is an arm 24. The arm has a generally rounded cross-sectional profile but includes a pair of opposed lobes projecting in the lengthwise direction of the lock bar 22. When the lock bar is engaged with slots 21, each arm projects into the carcass so that its free end lies closely adjacent the external side of the adjacent drawer. That drawer side carries a drawer stop 32 (Figures 6 and 7) for co-operation with an adjacent arm 24. As can be seen from Figure 3, the arms 24 are directly opposed to the respective bosses 23 except for the arm and boss at the end of the lock bar intended to be at the bottom of the drawer carcass -the arm and boss on the right of Figure 3. Here, the arm is substantially opposed to the boss but is offset -10-slightly along the length of the arm in order to allow that arm to lie closely adjacent the carcass base. However, both the arm and the boss lie within the enlargement 25 of increased thickness at this end of the lock bar.

The lock bar 22 is slidable between free and locked positions with the bosses 23 disposed towards the lower end of the respective slots 21 when the bar is in its free position. When the lock bar is raised to its locked position shown in Figure 6, the drawer stop 32 of each drawer will engage the adjacent arm 24 and so prevent the drawer from opening. A key-operated cylinder lock mechanism (not shown, though of conventional form) may be provided either on a drawer front or on a facia panel for the drawer assembly, for co-operation with the lock bar 22 to effect sliding movement thereof. The lock mechanism may have a pin projecting parallel to the axis of the cylinder but offset to one side and engaged between a pair of pegs projecting from the lock bar, in much the same manner as the arms 24. As shown in Figure 3, there are two such pairs of pegs 34, the pin of the lock mechanism engaging between the appropriate pair having regard to the position of the lock mechanism either on a drawer front or on a facial panel of the carcass.

Figure 7 shows in more detail the drawer stop 32 used in this embodiment. The drawer has a horizontal side rail 35 which is provided with a slot 36. A spring blade 37 having the profile shown in Figure 7 is engaged in that slot so as to project forwardly to the front of the drawer. That blade 37 has a ramp surface 38 and a stop surface 39 extending generally vertically at the forward end of the ramp surface, the stop surface being turned rearwardly to provide a lip 40 which may engage the side rail 35. Also shown in Figure 7 is the arm 24 of the lock bar in its free and locked positions.

When the lock bar is in its lower, free position, the drawer may be opened without restriction, by moving to the right in Figure 7. If the lock bar is in its upper, locked position, then arm 24 will restrain opening of the drawer, lithe drawer is open when the lock bar is moved to its locked position, the drawer may still be closed as the ramp surface 38 will engage the raised arm 24 and lift the stop surface 39 sufficiently to allow closing of the drawer. Once closed, the arm will return to its unstressed condition, with the stop surface engaging the arm 24 and preventing subsequent re-opening.

If an anti-tilt mechanism is required for the drawers, by way of an interlock arrangement which prevents the opening of any closed drawer once one drawer has been opened, a camming profile may be provided on each drawer so as to lift the lock bar from its free position to its locked position as any one drawer is opened. Such a camming profile may take the form of a plastics material moulding 42 attached to a drawer side, that profile defining a stop surface 43 and a slot 44 which ramps upwardly in the rearward direction, having regard to the direction of opening of a drawer. Arm 24 is shown in its locked position, so restraining opening of the drawer by being engaged by stop surface 43. When the lock bar 22 is in its free position, the drawer may be opened and on doing this, arm 24 will enter slot 44 and then be raised so as to move the lock bar to its locked position. In turn, this will restrain the opening of any of the other drawers until the lock bar is returned to its free position, by closing the open drawer.

If an anti-tilt mechanism is provided as described above, then the key mechanism must be arranged to permit the movement of the lock bar between its locked and free positions, by the opening and closing of a drawer. Further, -12 -means must be provided to restrain the lock bar in its locked position after arm 24 has come free of the rearward end of slot 44. For this purpose, a rounded protrusion 45 is provided on the lock bar 22, to co-operate with an aperture (not shown) in the side plate of the carcass, when the lock bar is in its raised position.

Should an attempt be made to open a drawer when the lock bar is in its locked position, the drawer stop 32 engages the adjacent arm 24 and applies a turning moment to that arm. This is resisted by the enlarged head 28 of the boss 23 opposed to that arm, in conjunction with the enlargement 25 on the lock bar in the region of that boss and arm, bearing on the side plate 15. This arrangement allows the opening force to be resisted solely by the arm 24, enlargement 25 and boss 23 in conjunction with the slot 21 engaged by that boss, without subjecting the lock bar 22 as a whole to significant torsional forces. As a consequence, the region of the lock bar between the pairs of bosses and arms need not have any great strength, and merely be sufficient to accommodate the tensile and compressive forces of moving the bar between its free and locked positions.

Figures 9 and 10 show parts of a modified form of lock bar, as compared to that shown in Figure 3. With this modified form of bar 49, it can be seen that there are two pairs of pegs 50, one of the pegs of each pair having a rounded profile remote from the bar 49. Generally opposed to each pair of pegs 50 is a respective L-shaped catch member 51 engageable in a slot provided in the side plate 15 of the carcass 10, to give support to the lock bar when being slid by a lock mechanism. The lock bar 22 has only one such L-shaped catch member opposed to one pair of pegs 34, a boss 23 being provided opposed to the other -13-pair of pegs 34. However, for convenience of fitting the modified bar 49, two such L-shaped catch members 51 are provided, as each of those requires the provision of a narrower slot in the side plate 15 of the carcass.

As shown in Figure 9, there are two shallow transverse grooves 52 formed across the lock bar 49 in the region of each of the pairs of pegs 50. As best seen in Figure 10, the arm 24 at the lowermost end of the lock bar is displaced slightly towards the end of the lock bar 49 from the opposed boss, to allow accommodation of the drawer-engaging mechanism. Also, a protrusion 53 is provided on the bar 49 which protrusion has a slightly modified shape as compared to protrusion 45 on lock bar 22.

Having regard to the strength requirements of the lock bar, either form can be made as a one-piece plastics material moulding. An advantage of this is that one moulding may serve for a number of different drawer assemblies, simply by cutting the moulding to the required length.

Claims

-14 -

CLAIMS

1. A drawer locking system for a drawer assembly including a plurality drawers and a side panel adjacent the drawers, which locking system comprises: -a multiplicity of slots provided in the side panel, there being a respective slot associated with each drawer; -an elongate lock bar having a plurality of bosses on one side thereof, the bosses being engaged in the slots for sliding movement of the lock bar parallel to the side panel between free and locked positions, there being means to retain the bosses engaged with the slots; -a plurality of spaced arms projecting from the other side of the lock bar each substantially opposed to a boss on said one side of the bar, there being a respective arm and boss for each drawer of the drawer assembly; and -a stop member on each drawer engageable with a respective arm when the drawer is closed and the lock bar is in its locked position so as to prevent opening of the drawer, but which stop member may freely pass the arm when the lock bar is in its free position, to allow opening of the drawer.

2. A drawer locking system as claimed in claim 1, wherein the lock bar is made of a plastics material, as a one-piece moulding.

3. A drawer locking system as claimed in claim I or claim 2, wherein each side panel comprises a metal plate or frame member of a carcass for the drawer assembly.

4. A drawer locking system as claimed in claim I or claim 2, wherein each side panel comprises an insert fitted into a solid wood or wood-derived panel forming a part of a carcass for the drawer assembly.

5. A drawer locking system as claimed in claim 1 or claim 2, wherein each side panel comprises a vertically extending plate secured to a solid wood or wood-derived panel forming a part of a carcass for the drawer assembly.

6. A drawer locking system as claimed in any of the preceding claims, wherein each slot is enlarged at one end, to facilitate the connection thereto of a boss of the lock bar.

7. A drawer locking system as claimed in claim 6, wherein each slot is of a key-hole shape whereby a boss may be entered into the enlarged end of the slot and then slid to engage the narrower part of the slot.

8. A drawer locking system as claimed in claim 6 or claim 7, wherein each boss has a first portion adjacent the lock bar and which has a width slightly less than the width of the narrower part of the slot and an enlarged head the shape of which may fit through the enlarged end of the slot.

9. A drawer locking system as claimed in any of the preceding claims, wherein there is provided a region of increased thickness on the lock bar where a boss and opposed arm connect therewith, which region presents a flat bearing surface to the side panel in which is defined the slot engaged by the boss.

10. A drawer locking system as claimed in any of the preceding claims, wherein a key-operated lock mechanism is arranged to effect movement of the lock bar between its free and locked positions.

11. A drawer locking system as claimed in claim 10, wherein the lock bar is provided with a pair of spaced pegs for co-operation with a pin projecting from the barrel of a cylinder lock mechanism, whereby operation of the lock -16 -mechanism effects sliding movement of the lock bar between its free and locked positions.

12. A drawer locking system as claimed in any of the preceding claims, wherein the lock bar is movable between its free and locked positions by means of a camming profile provided on each drawer and co-operable with the arm associated with that drawer, on moving the drawer between closed and open positions.

13. A drawer locking system as claimed in claim 12, wherein a detent arrangement is provided to maintain the lock bar in its locked position when moved there by the opening of a drawer.

14. A drawer locking system for a drawer assembly including a plurality drawers and a side plate adjacent the drawers and substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings.

15. A drawer assembly whenever incorporating a drawer locking system as claimed in any of the preceding claims.