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(11) | EP 0 499 446 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Joints for use in racking or shelving systems |
| (57) A joint between an upright support (12) and a projecting member (11) such as a shelf
comprises lugs (31,33) on the projecting member for engagement in slots (27) in wall
(20) of the upright member. The lugs have recesses (34,39) so that inserting a lug
into a slot and lowering the projecting member engages the lug in the slot. A wedging
action is provided by tapered edge (36) of recess (34), tapered edge (37) of recess
(39) and by tapered edges in the slots (27), the tapers reducing the width of the
slots and recesses respectively to equal to or less than the thickness of the projecting
member and wall respectively. |
[0001] The invention relates to a joint between an upright support and a projecting member for use in a racking or shelving system.
[0002] One well known kind of joint comprises generally vertical slots in a wall of an upright support and lugs on the projecting member for engagement in the slots, each lug comprising a recess in its underside such that inserting a lug into a slot and lowering the projecting member carrying the lug causes the recess in the lug to engage around the wall at the base of the slot. This kind of joint is entirely satisfactory in many situations. The projecting member may be a shelf and this kind of attachment is normally satisfactory when the self can be supported at both of its ends.
[0003] Display shelving systems in retail outlets normally incorporate a series of uprights positioned along a line corresponding to the rear of the shelves, with shelves cantilevered to the uprights and extending to one or both sides of the row of uprights. Each shelf can be supported at both ends so conventional joints may be used. In double sided shelving units it is also desirable to have shelves extending across the ends of the shelving system. The centre of the rear of the end shelf can be carried on an end upright. This does not normally provide sufficient support for the whole shelf so it is normally necessary to provide additional uprights which have to be positioned at a location where they interfere with free access to the end or side shelves.
[0004] An objective of the invention is to provide an improved joint which is particularly useful for end shelves in a shelving system but which can be used in other situations.
[0005] The invention relates in particular to a joint between an upright support and a projecting member for use in a racking or shelving system, the joint being of the kind comprising generally vertical slots in a wall of an upright support and lugs on the projecting member for engagement in the slots, each lug comprising a recess in its underside so that inserting a lug into a slot and lowering the projecting member carrying the lug causes the recess in the lug to engage around the wall by the base of the slot.
[0006] A joint of this kind is already known from GB A 680327. The lugs in this known arrangement have inclined edges. These inclined edges in conjunction with other parts of the installation provide a wedge action in securing the shelf to the upright. The individual elements providing the wedge action are spaced well apart so that the effectiveness of the wedging is influenced by the inevitable flexibilities of the shelf and upright.
[0007] A further joint of the kind referred to which also has tapered recesses is known from GB A 1455982.
[0008] In accordance with the present invention a joint between an upright support and a projecting member of the kind referred to above is characterised in that either the recess is tapered from a width greater than or equal to the thickness of the wall to a width at the root of the recess which is less than that of the wall or the slot is tapered from a width greater than or equal to the thickness of the lug at the top of the slot to a width less than the thickness of the lug at the bottom of the slot.
[0009] With this arrangement, the wedging action occurs directly at the point of engagement of a lug in a slot, giving a more positive and direct engagement.
[0011] Preferably the projecting member is cantilevered to the upright, upper and lower lugs in a support engage in separate slots, the recess in the upper lug has a vertical inner edge and inclined outer edge and the recess in the lower lug has an inclined inner edge and a vertical outer edge. This arrangement ensures that the angle of the projecting member is set by engagement of vertical surfaces on the lugs while the inclined edges allow wedging action.
[0012] The joint may include a set of at least two lugs, one above the other, to one side of the upright and at least one other lug to the other side of the upright. The projecting member may be a shelf incorporating a torsionally stiff box section member 11 extending across the shelf from the vicinity of the joint. This arrangement helps to provide a stiff well supported shelf structure.
[0013] An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings in which:-
Figure 1 is a perspective view from below of a shelf intended to be supported by a joint according to the invention;
Figure 2 is an end elevation of part of an upright for supporting the shelf;
Figure 3 is a plan view of the upright shown in Figure 2; and
Figure 4 is a side elevation through part of the shelf and part of the upright showing the joint therebetween.
[0014] The shelf shown in Figure 1 is to be supported on an upright 12 at the centre of the rear of the shelf in such a way that no other support is needed. To this end, the shelf itself needs a high degree of strength and rigidity and similarly it needs a firm rigid joint by which it is mounted to the upright.
[0015] The shelf incorporates a central torsionally stiff fabricated box-section member 11 cantilevered to upright 12 in a manner to be described subsequently. At its outer end, member 11 carries a box-section transverse member 13. At its inner end it carries two transverse brackets 14. Two further shelf edge members 15 join the outer ends of brackets 14 and box member 13. Diagonal stiffening brackets 16 and 17 are also provided. The shelf surface is provided by a flat sheet member 18. The whole shelf structure is fabricated from sheet steel elements which are welded together to form the whole structure.
[0016] A typical upright 12 is shown in greater detail in Figures 2 and 3. The upright is a box-section steel member formed by welding together two separate folded U-shape components along the two weld lines 21 and 22. The upright itself has to be supported as part of a shelving system for a retail shop of a kind known as a gondola. A typical gondola is in effect a free standing upright wall with shelves projecting to both sides from the wall and with further shelves across the ends of the wall. Upright 12 is at one end of the main wall of the gondola. The upright is suitably braced within the wall to withstand force applied to it by the shelving loads placed upon it. The upright incorporates various series of slots 23, 24, 25 and 26 which are intended for joining the upright to other parts of the structure with which the present invention is not concerned. The upright also incorporates a series of slots 27 which are intended for mounting the shelf of Figure 2. Each slot 27 is generally vertical and the upper part of each slot is parallel sided. Each slot 27 is intended to receive a lug such as 33 of the shelf 17 and its parallel region is wider than or possibly equal to the thickness of one of these lugs. Towards its lower end, the slot tapers to a width which is less than the thickness of a lug 33. In this example, approximately fifty percent of the outer edge of each lug is inclined and approximately twenty percent of the corresponding inner edge of the lug is inclined. The angle of inclination in this example is seven and a half degrees giving a total taper angle of fifteen degrees near the bottom of the slot.
[0017] There are two rows of slots 27, with each row placed as far out as possible on one of the major faces which forms a wall 20 so that the material close to the slot is supported by a fold in the material. A large number of these slots are spaced out at equal pitch along a major part of the length of the upright 12 to provide spaced attachment points for the shelf and to allow for alternative shelf height positions.
[0018] If slots 27 are formed before the sheet material is folded, the slots would probably distort. To avoid this distortion, the slots are provided after the folding operation by laser cutting or by a suitable mechanical punching operation.
[0019] Figure 4 shows part of the bracket 11 of Figure 1 and also gives details of lugs by which the shelf is mounted on or joined to the upright 12. Each sheet metal side member 30 of the box-section bracket 11 incorporates three generally rectangular lugs 31, 32 and 33. Lug 31 incorporates a recess 34 in its underside at its root where it joins the rest of member 31. The recess has a vertical inner edge 35 and an inclined outer edge 36.
[0020] The taper of the recess in this example is at an angle of fifteen degrees and is such that the bottom of the recess is wider than or possibly equal to the thickness of the front wall 20 of the upright but the recess tapers to a width which is less than the thickness of the wall 20. Lug 32 corresponds to lug 31 except that the recess is untapered. Lug 33 corresponds with lug 31 except that the inner edge 37 as opposed to the outer edge 38 of the recess 39 is inclined. Only one side member 30 is shown but there are two such side members, one to each side of the box-section member 11. Lug 32 has a parallel sided recess 41.
[0021] In order to mount the shelf shown in Figure 1 on the upright shown in Figures 2 and 3, the shelf is offered up to the upright and all six lugs are inserted in corresponding slots 27. The shelf is then lowered so that the recesses in the undersides of the lugs engage in the material of wall 20 near the bottom of a slot. This engagement of slots and lugs results in a double wedging action for lugs 31 and 33. In particular, the thickness of wall 20 of the upright wedges in the tapered recesses associated with lugs 31 and 33. Similarly, the lugs themselves wedge in the tapered lower part of the slots. During assembly, the shelf is firmly pushed down to establish a firm wedging action at each interconnection of a lug in a slot.
[0022] The shelf is loaded as a cantilever and the cantilever couple is reacted by an outward force on the lower end of the bracket in the region of lug 33 and inward forces on the outer edges of the recesses in lugs 31 and 32. It is for this reason that tapered recess 34 of lug 31 has a flat inner edge and that two lugs 31 and 32 are provided near the top of the bracket to spread the load over a region of two slots. At the lower end, the vertical line corresponding to the outer edge of the recess in the lug extends both above and below the lug to provide a spread out bearing surface. Because the upper and lower bearing surfaces are vertical, the shelf does not tend to tilt as the wedging action is increased.
[0023] The mounting for the shelf provided by the wedge action of the lugs in the slots results in a sufficiently stable shelf 11 to enable the shelf to be loaded asymmetrically with merchandise without causing it to tilt. The shelf itself may even be longer on one side than the other. The shelf may also be inclined in any direction.
[0024] As an alternative in some situations, sufficient wedging action and accuracy of location may be arrived at by tapered lug recesses and parallel slots or with parallel slots and tapered lug recesses. However, it is preferred to taper both slots and recesses to provide a more secure wedging action.
[0025] The shelving system may be modified by varying the number of lugs in engagement. Two lugs may be sufficient in some cases, the number being chosen to give adequate support for anticipated loads. Normally two equal sets of lugs are provided, one to each side of the upright but a satisfactory arrangement can be achieved with two lugs one above the other to one side of the upright and a further lug to the other side of the upright.
[0026] Throughout this specification we have referred to member 12 as an upright. However, it is not necessary for the upright to be truly vertical. Assembly under gravitational loads and resulting wedge action could be effective with the so called upright set at an angle so the term "upright" is intended to refer also to a member which has some inclination to the vertical.
[0027] Joints of this kind may be used in several other situations. For example, the projecting member could be supported at both ends instead of being cantilevered although the positive joint provided by the present invention is not then normally necessary. Similarly the projecting member need not be a shelf; for example it could be a bracket on which merchandise is to be hung or could be a structural member in a framework.
[0028] Also the upright is not necessarily a box-section member. It could be any structure with a wall of sufficient strength and rigidity to support the projecting member.
[0029] Although it is preferable for both the slots in the upright and the recesses in the lugs to be tapered effective joints can be achieved with wedge action from only one taper. Similarly, the slot may taper down to the actual thickness of the lugs to prevent lateral free play, leaving all or most of the wedging action to be achieved by the taper of the recesses.
[0030] The preferred fifteen degrees taper angles are not critical. Angles as low as eight degrees or as high as forty degrees may prove to be satisfactory.
[0031] Close tolerances are needed in the dimensions and positions of the slots and recesses. These can be achieved by laser cutting or by press tool methods. The material of the members is normally mild steel which deforms slightly on establishment of the wedge action. This deformation also accommodates slight inaccuracies in the dimensions or positions of slots or recesses.
1. A joint between an upright support (12) and a projecting member (11) for use in a
racking or shelving system, the joint comprising generally vertical slots (27) in
a wall of an upright support and lugs (31,33) on the projecting member for engagement
in the slots, each lug comprising a recess (34,39) in its underside so that inserting
a lug into a slot and lowering the projecting member carrying the lug causes the recess
in the lug to engage around the wall (20) by the base of the slot, characterised in
that either the recess (34 or 39) is tapered from a width greater than the thickness
of the wall to a width at the root of the recess which is equal to or less than that
of the wall or the slot (27) is tapered from a width greater than the thickness of
the lug at the top of the slot to a width equal to or less than that of the lug at
the bottom of the slot, whereby the lug can be wedged in the slot.
2. A joint as claimed in Claim 1 characterised in that both the slot and the recess are
tapered as specified in Claim 1.
3. A joint as claimed in Claim 2 characterised in that the projecting member (11) is
cantilevered to the upright (12), and incorporates upper and lower lugs (31,33) engaged
in separate slots (27), a recess (34) in an upper lug (31) has a vertical inner edge
(35) and inclined outer edge (36) and a recess (39) of a lower lug (33) incorporates
an inclined inner edge (37) and a vertical outer edge (39).
4. A joint as claimed in Claim 3 characterised by at least one further lug (32) having
a parallel sided recess (41).
5. A joint as claimed in any one of the preceding claims characterised by a set of at
least two lugs, one above the other, to one side of the upright and at least one lug
to the other side of the upright.
6. A joint as claimed in Claim 5 wherein the projecting member is a shelf incorporating
a torsionally stiff box section member (11) extending across the shelf from the vicinity
of the joint.
7. A joint as claimed in Claim 6 further comprising a transverse member (13) at the outer
end of the box section member.