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(11) | EP 0 019 020 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Door and method of construction thereof |
| (57) A light weight door for a caravan is made as a sandwich from two panels (20,22) with
an infilling of a wooden frame consisting of rails (36,38) and stiles (32) which are
not jointed together, and with blocks (26) of expanded polystyrene filling the spaces
between the rails and stiles, these blocks being initially thicker than that of the
wooden frame parts, and all of the parts being bonded together so that the blocks
become compressed. The bonding is carried out such that the door is concave convex
at the latch edge but planaratthe hinge edge so that in closing the door the top and
bottom ends of the door abut the door frame first and to bring the latch into registry
with its keeper on the door frame it is necessary to press or pull the middle part
of the door against the frame thus straightening out the concave convex edge This
assures better sealing of the door within its frame and reduces any tendency for the
door to stick. |
[0001] This invention relates to doors particularly for use on caravans, cabin cruisers, portable buildings and similar applications where a relatively inexpensive and lightweight door is required.
[0002] A major problem with such doors is in securing an adequate seal with the surrounding door frame. Owing t.o their lightweight and flimsy nature, such doors have a tendency to warp especially when of jointed construction and undergo deformation when pressed against a sealing member interposed between the door and the frame. Moreover there is a tendency for such doors to stick when fitted to structures which are not entirely rigid. The natural reaction therefore is to restrict the use of such doors to internal uses and to adopt doors of more robust construction for external use.
[0003] The primary object of the present invention is to overcome the aforesaid drawbacks. Other objects are to provide a lightweight door which can be provided with at least one face which can be matched in appearance to that of the wall in which the door is to be mounted, thus minimising any subsequent finishing treatments required, and which can be readily made with either radiussed corners or top and/or bottom edges, which is required both for aesthetic purposes and in order to provide greater strength in the associated door frame without complicating the structure of the same.
[0004] In accordance with a first aspect of the invention we provide an assembly comprising a door and a door frame to one side of which the door is adapted to be hinged, the opposite side of the frame being provided with a keeper for co-operation with a latching member provided at the non-hinged longitudinal edge of the door intermediate the top and bottom ends of the door, characterised in that said non-hinged longitudinal edge is of concave/convex configurationöuch that upon door closure, the top and bottom ends thereof abut the door frame before the intermediate portion at which the latching member is provided and to allow the latching member to engage with the keeper the door must be pressed against the frame to cause said non-hinged longitudinal edge to straighten sufficiently to bring the latching member into registry with the keeper, the non-hinged longitudinal edge returning to its original concave/convex configuration upon disengagement of the latching member from the keeper.
[0005] In accordance with a second aspect of the invention we provide a method of making such a door comprising locating on a first planar panel a plurality of separate wooden edge parts to form an unconnected and unjointed frame, as an optional feature locating separate blocks of expanded plastics material between selected areas of said frame, said blocks (if present) having a thickness greater than that of the wooden edge parts, and locating a second planar panel on the assembly so formed, the frame and the panels being generally rectangular but with at least two adjacent corners optionally of the rectangle radiustsed, and bonding the whole assembly together so that the panels become bonded to opposite faces of said blocks (if present) and edge parts and so that the blocks (if present) are compressed in the direction of their thickness, the bonding being effected so as to impart curvature to the door so that the door is planar at its hinge edge and concave/convex at its non-hinged longitudinal edge.
[0006] lt is preferred to effect the bonding operation between matched dios and it has been found in practice that this can be done with a stack of assemblies, for example with ten doors one above the other located between the upper and lower dies of a press.
[0007] The matched dies may additionally effect the aforesaid shaping of the doors so that each door is truly planar at the hinged longitudinal edge which is intended to be provided with hinges, and concave/convex at the non-hinged longitudinal edge. The concavity will be on the internal fact: of the door (in use) and the convexity on the external face, and this may be of the order of say 1 to 2cm out of planarity at each of the top and bottom of a normal 2 metre or thereabouts, high door. The effect of this will be that when the door is closed, assuming that it opens outwards from the for example caravan, the top and bottom corners of the door will register with the door frame initially and continued closing movement by a handle located approximately mid-way up the height of the door will tend to take the door latch into engagement with a keeper provided on the door frame and to flatten the door inwards towards true planarity. In this way pressure can be applied to a seal interposed between door and frame and such pressure will not permanently distort the door because the latter will tend to return to its concave/convex configuration. This flattening operation will also increase the vertical height of the door at the front edge so that it tends to fill the door frame more completely. In opening, when the handle is operated to release the latch from the keeper, the door will tend to return to the concave/ convex shape thus reducing the overall height of the door and freeing the top and bottom corners from the frame, thus avoiding problems with the door sticking to the frame, which problems are particularly prevalent with lightweight doors fitted to structures which are not entirely rigid.
[0008] When the door has been removed from the matched dies after having effectively set in the required position due to the operation of the bunding adhesives, the whole of the periphery of the door may be enclosed in an extruded metal channel section which extends for example from a mid-point at the bottom of the door around the whole of the periphery and with the ends of the extrusion abutted. The extrusion can be held to the wooden frame at a small number of selected points for example by wood screws, and the extrusion also serves Lu mount draught excluder seals, hinges and other door furniture.
[0009] the One ofjpanels may comprise hardboard and the other of the panels may comprise a piece of sheet metal where, for example, the door is to be used for a caravan, and the exterior of the caravan is formed of sheet metal which may be plastics coated, anodised, spray painted or otherwise treated, the sheet metal panel used for the door of the invention may be made of the same finished or treated material so that it will inherently match the caravan wall without subsequent treatment, and hence the sheet metal panel will form the exterior face of the door. Similarly, if the interior of the caravan is lined with hardboard as a wall material, and this is painted, papered or otherwise finished, the hardboard panel used in making the door may be treated in identical fashion, again so that no subsequent treatment is necessary. However, it is also intended to be within the scope of the invention to use two hardboard or like panels, or two sheet metal or like panels instead of one of each.
[0010] The edge parts may comprise rails and probably also stiles generally made of wood of square or rectangular cross section, and there are several possibilities for forming the door with the radiussed corners which enables the door to be used in association with a door frame which is similarly made of a length of extruded metal section of appropriate cross sectional shape, and which can be curved or bent to form the complete door frame, instead of using a plurality of separate pieces jointed at the corners (because the complex and usually extruded section used cannot be folded to a right angle). This greatly simplifies the construction of the door frame whilst making it very much more rigid.
[0011] In one possibility the stiles which form the longitudinal side edges of the door at this stage of the assembly and which may be generally straight will have square cut end::, and two of the rails, which are to form the top and bottom edges of the door at this stage of the assembly and which are also generally straight will have radiussed ends (or vice versa). By radiussed ends it is meant that when these rails are placed flat upon the one panel, their adjacent faces extending normally of the panel will be planar so that the end portion of these faces can abut approximately against the square cut ends of the stiles, but the two faces which are remote from each other will have generally curved ends which sweep in a smooth arc from the outer faces of the stiles to merge into the parallel portions of the outer faces of these rails.
[0012] A second method of providing the radiussed corners is to use generally straight stiles and rails with square cut ends, but which are spaced apart at the "corners" of the panel, with a corner block located at each corner which is to be radiussed, the corner blocks having for example two faces which meet at a right angle towards the interior of the door and which are joined by a smooth curve forming the external "corner".
[0013] A third method, when the whole of the top (or bottom, or both) is to be radiussed is to use a pre-formed curved rail or rails.
[0014] ln general, either the two top corners'of the door (in use) will be radiussed (including the possibility of the two radii having a common locus) or all four corners of the door will be radiussed or so radiussed.
[0015] The stiles, rails and corner blocks if used, are to form an unconnected and unjointed frame. That is to say these wooden components are to be placed together so that they approximately abut, but without any mortice and tenon or other joint formed between the parts, and without any brackets or connecting plates. The importance of this is so that in the event of any warping arising in any one wooden component, this will not be transmitted around the frame by joints and will have minimum effect on the planarity of the door.
[0016] The wooden frame may also include additional components, generally in the form of rails in the sense that they are to extend transversely of the door, although possibly in the form of additional vertically extending components, particularly so that any desired aperture in the door per se which is to be filled by a window, ventilator or the like, will be generally surrounded by a peripheral sub-frame of wood, again in the unjointed and unconnected form.
[0017] In general, each cavity formed between several of the wooden components, other than those where windows or ventilators are to be fitted, will be used to locate a correspondingly shaped block of expanded plastics material, which may be polystyrene, polyurethane or the like. Such material is inherently weak and fragile, but gives substantial strength and rigidity to the assembled door when bonded in place over the whole of the face area of the blocks and when subject to small compression inherent through the use of blocks which are of greater thickness than the wooden components.
[0018] One of the cavities between the wooden members may be used to locate a slab of denser material, for example chipboard, particularly where a door lock is to be assembled and where the chipboard can serve to receive the necessary wood screws. Since the chipboard is less compressible, than the plastics material, it will be of the same thickness as the other wooden compbnents.
[0019] Prior to making the assembly, the panels are coated with an appropriate bonding adhesive, which may be one which is non-tacky to the touch, and which requires to be pressure bonded, and the wooden components, the plastics slabs, and the chipboard if used are coated with the same adhesive on both faces. The assembly of wooden components, plastic:; slabs, and chipbuurd if used is then arranged in appropriate fashion on one panel, and the second panel is superimposed.
[0020] The invention is now more particularly described and illustrated with reference to the accompanying drawings wherein:-
Fig. 1 is a some what dragrammatic elevation of a door;
Fig. 2 is a similar diagrammatic elevation of a second door;
Fig. 3 is a sec-tion taken on the line 3-3 of Fig. 2;
Fig. 4 is a section taken on the line 4--4 of Fig. 2;
Fig. 5 is a section on the line 5--5 of Fig. 2;
Fig. 6 is an enlarged fragmentary and diagrammatic view showing a portion of an assembly partway through'manufacture of the door;
Fig. 7 is a view similar to Fig. 6 showing an alternative;
Fig. 8 is a further diagrammatic view showing the arrangement of parts in a part assembled door;
Fig. 9 is a sectional elevation of a practical embodiment and Figs. 10 and 11 are transverse sections of the door of Fig. 9.
[0021] Turning now to the accompanying drawings and particularly Fig. 1 thereof, the door shown therein is a typical caravan door having upper radiussed corners 12 and lower square corners 14. The side edges of the door are not truly parallel as there is some shaping to give a slight convergence of the side edges towards the top. The door is provided with a window diagrammatically indicated by the reference 16 and a ventilator shown by the reference 18. The door shown in Fig. 2 is generally similar to that in Fig. 1, except for the purposes of illustrating other possibilities it is shown as having parallel side edges and radiussed corners at all four corners of the generally rectangular shape.
[0022] Figs. 3 and 4 show the shaping of the door previously referred to, so that in Fig. 3 the concave-convex shape is seen, and in the chain-dot line this Figure illustrates the slight deformation which takes place when the door is closed and latched. The curvature has been substantially exaggerated in Fig. 3 for the purpose of illustration.
[0023] Fig. 5 shows a typical cross section of an assembly prior to the bonding stage, including a thick panel for example of hardboard shown by the reference numeral 20 assembled with a thin panel for example of sheet metal shown by the reference numeral 22 and sandwiched between the two a number of wooden stiles or rails 24 and a number of thicker blocks of expanded plastics material 26.
[0024] Figs. 6 and 7 show two of the alternative possibilities at the corners, Fig. 6 showing the arrangement with a corner block located between a strle 32 arid a rail 34, and Fig. 7 showing the rail 36 substantially abutting against the stile 32 but with the end portion of the rail being radiussed at 37. It will be noted that in both cases the panel is generally shaped to the radii required prior to assembly, and in both cases the actual clearances are exaggerated.
[0025] Fig. 8 shows a typical arrangement of parts on one panel, prior to locating a second panel in place and press bonding the complete door, including a pair of stiles 32 located at the opposite longitudinal edges of the door, a pair of rails 36 located at the top and bottom of the door, a series of transverse rails, which serve with the other rails and stiles to define a series of cavities, ones of which such as 40 42 are approximately filled with blocks of expanded plastics material, a further one of which 44 locates a block of chipboard for securing a lock, and another of which 46 is to define the general area of a window or the like aperture.
[0026] Turning now to Figs. 9 and 11, which are different sections through a typical door in accordance with the invention, it will be seen that this is made in two parts, comprising an upper portion shown by the reference numeral 50 and a lower portion 52, these being arranged so that the upper portion can be opened alone (for maximum ventilation) or the two portions can be opened together. Such a door is sometimes called a "stable door". The two portions can be collectively assembled and manufactured completely as a single unit, prior to the addition of the extruded metal sections around the peripheries of the respective-parts.
[0027] The upper part comprises wooden rails 54 56, additional transversely extending wooden rails 58, blocks of the plastics foamed material 60, a window unit comprising a glass pane 62 assembled in a rubber or like plastics sealing ring 64 within an extruded metal frame 66 which is fixed in place by screws 68 with an interposed gasket 70, and with the heads of the screws hidden by a snap-in plastics strip 72 engaged in a dovetail channel provided for the purpose in the extrusion. It will be noted that the screws here go directly into the wood. In an alternative (not shown) the window is double glazed. In either case the frame may be of plastics or rubber, with or without a metal frame.
[0028] In the case of the lower portion, a ventilator is provided with louvres 74 formed in to the sheet metal panel 76 which covers the exterior face of the door, and here a portion of the panel 76 is bent at 78 in the case of the lower part of the door and at 80 in the case of the upper part of the door to extend over the adjacent edge parts of the two door portions. The ventilator is completed by an assembly 82 fixed to the hardboard or like (for example plywood) panel 84 which forms the inner skin of the door, that is the face adjacent the interior of the portable building or the like where the door is used.
[0029] The longitudinal edges of the door and also the top and bottom are enclosed in channels of extruded metal, each of which is of generally U shape, with the limbs of the U embracing the side edges, these extrusions being generally indicated by the reference numeral 86.
[0030] These extrusions are held in place by further screws 18 which engage in the rails and stiles respectively as seen in Figs. 9, 10 and 11. The upper edge of the lower door portion is provided with an additional extrusion 90 which is formed with an integral ribbed flange 92 of "barbed arrow" cross-section uo as to be a press-fit into a slot provided for the purpose in the rail at that edge of the door portion, and this extrusion also has an additional flange 94 which forms an abutment for the upper portion of the door when the two portions are generally co-planar.
[0031] It will be appreciated that in this arrangement of a split door, a latch is provided, conveniently on the upper door portion, and Fig.lO shows a typical transverse cross section clear of the latch. In addition to the latch, the door will be provided with locking means, such as a turnbuckle arrangement for locking the door portions together so that they swing together as a single door, and a second locking means, e.g. a turnbuckle arrangement, for lastening the lower door portion to the frame when the top portion only is to be opened. It will be noted that the extrusion 86 is formed with a hollow box-like flange 98 to anchor a rubber or like plastics sealing strip generally indicated at 100 which includes a portion of hollow box-like section 101 which can be compressed and deformed between the extrusion 86 and a co-operating inclined portion 102 of the door frame extrusion 104. The rubber or like strip 100 includes a flap 103 to seat on the door as a draught- excluding seal. The strip 100 extends around the whole of the door. The extrusion 104 has a similar dovetail channel and sealing strip 72 as used in the case of the window frame, to enable the door frame to be secured to the surrounding structure by wood screws, and the heads of the screws to be hidden. The typical latch construction 106 includes a conventional pivoted internal and external lever handles 108 and 150 and a latch belt 110.
[0032] Fig. 10 shows the latch side of the door, and Fig. 11 shows the hinge side, the hinge comprising leaves 112 113 fixed respectively to the extrusion 86 which is fixed to the door and to the door frame 102. It will be noted that the door frame includes the channel 114 extending along its length, which has inturned edges 115 used to anchor a flexible strip 116 along the hinge edge of the door, and which can seat on the flap 10; at 118 and on the adjacent edge of the wall at 120 as a secondary draught excluder, and similarly at the latch edge of the door. It will be appreciated that in Fig, 10, the door opens in the direction of the arrow A. The strip 116 has a portion of "arrow head" cross section which can be pushed into the box-section 114 and recover to hold the strip in position.
1. An assembly comprising a dour und a door frump tu one side of which the door is
adapted to be hinged, the opposite side of the frame being provided with a keeper
for co-operation with a latching member provided at the non-hinged longitudinal edge
of the door intermediate the top and bottom ends of the door, characterised in that
said non-hinged longitudinal edge is of concave/convex configuration, such that, upon
door closure, the top and bottom ends thereof abut the door frame before the intermediate
portion at which the latching member is provided and to allow the latching member
to engage with the keeper the door must be pressed against the frame to cause said
non-hinged longitudinal edge to straighten sufficiently to bring the latching member
into registry with the keeper, the non-hinged longitudinal edge returning to its original
concave/convex configuration upon disengagement of the latching member from the keeper.
2. A modification of the assembly claimed in Claim 1 or 2 characterised in that which
there are two door parts, a top door part and a bottom door part, which are separately
hingedly connectible to said one side of the door frame and are adapted to be releasably
coupled so as to hinge together as a single door whose non-hinged longitudinal edge
is of concave/convex configuration as aforesaid, one of said door parts being provided
with a latching member as aforesaid for co-operation with said keeper.
3. The door of Claim 1 or 2 characterised in that the door comprises a pair of generally
planar panels with a wooden frame located between the panels, said frame comprising
a number of stiles and rails which are not jointed together thereby avoiding any stresses
that would otherwise arise in joints between the rails and the stile disposed at said
non-hinged longitudinal edge.
4. The door of Claim 3 characterise in that blocks of expanded plastics material are
located between selected ones of the stiles and rails, said blocks being compressed
in the direction of the thickness of the door.
5. The door of Claim 4 characterised in that said stiles and rails are adhesively
bonded to said panels.
6. The door of Claim 3, 4 or 5 characterised in that at least two of its adjacent
corners are radiussed.
7. The door of Claim 3, 4, 5 or 6 characterised in that its hinged marginal edge is
truly planar.
8. A method of making the door of Claim 3 comprising locating on a first planar panel
a plurality of separate wooden edge parts to form an unconnected and unjointed frame,
as an optional feature locating separate blocks of expanded plastics material between
selected areas of said frame, said blocks (if present) having a thickness greater
than that of the wooden edge parts, and locating a second planar panel on the assembly
so formed, the frame and the panels being generally rectangular but with optionally
at least two adjacent corners of the rectangle radiussed, and bonding the whole assembly
together so that the panels become bonded to opposite faces of said blocks (if present)
and edge parts and so that the blocks (if present) are compressed in the direction
of their thickness, the bonding being affected so as to impart curvature to the door
so that the door is planar at its hinge edge and concave/convex at its non-hinged
longitudinal edge.
9. The method claimed in Claim 8 wherein the bonding is effected between matched dies
and a stack of doors, each comprising planar panels and edge parts as aforesaid, are
bonded in one operation between the upper and lower dies.
10. An assembly as claim d in any om of Claims 1 - 3 characterised in that the frame
is radiussed at at least two corners thereof and the corresponding door corners arc
correspondingly radiussed, the frame being constituted by a continuous length of extruded
metal curved or bent at said corners.