EP0364474B1

EP0364474B1 - Tiles for playground surfaces

Info

Publication number: EP0364474B1
Application number: EP19880904997
Authority: EP
Inventors: Alan David Browne; Andrew Bryan Yates
Original assignee: SMP Playgrounds Ltd
Current assignee: SMP Playgrounds Ltd
Priority date: 1987-06-16
Filing date: 1988-06-13
Publication date: 1992-09-16
Anticipated expiration: 2008-06-13
Also published as: EP0364474A1; JPH03500311A; DE3874740T2; DE3874740D1; WO1988010339A1; GB8713995D0; AU1938888A; AU611176B2

Abstract

A tile of rubber or the like has hollow cylindrical projections (5) extending from the underside of a sheet (4) and adapted to buckle to cushion impacts against the upper surface of the tile. The tiles, and edge strips (2) which are laid around the tiled area to define a smooth transition between the surfaces of the tiles and the surrounding ground surface, are fixed to the ground by fixing members (15) which tightly embrace the projections on the underside of the tiles and edge strips.

Description

This invention relates to tiles for covering playground surfaces.
In order to reduce risk of injury to falling children it has become usual to cover hard ground surfaces under and around play structures, such as swings, slides, climbing frames, etc. with a layer of material such as rubber having energy absorbing properties. As well as providing cushioning against falls, the surface layer reduces the chances of cuts and abrasions. The surface layer can conveniently be applied in the form of tiles of rectangular, especially square shape. In order to prevent unintentional movement and unauthorised removal of the tiles they are firmly affixed to the underlying surface and to each other by adhesive. This fixing technique has the disadvantages that great care is needed when laying the tiles to ensure that they abut tightly together and no gaps which would collect dirt and form trip points are left. Furthermore, replacement of individual damaged tiles is a difficult problem.
Known in the art are generally flat solid tiles which can be laid on top of a level ground surface. A ramp edge can be laid around the tiled area to provide a smooth gradual transition from the surrounding ground surface to the tile surface. EP-A-117707 discloses a floor mat assembled from a number of tiles of grid like structure. The tiles have edge formations enabling them to be interlocked with each other, ramp strips being provided for the edge of the mat. These tiles provide only limited energy absorption under impact due to their relatively small thickness. An alternative form of tile having better energy absorbing characteristics consists of a flat upper sheet or pad from the lower side of which projects a multiplicity of integral conical studs. DE-A-2614095 discloses a floor tile of resilient material having hollow rectangular elements open at their bottom faces. GB-A-1122009 discloses a tile having a perforated upper sheet provided with cylindrical projections on the underside. Half projections are formed at the edges of the tiles so that adjacent tiles can be securely fastened together by a connector. The length of the projections found in the prior art is several times the thickness of the upper sheet, and the tile as a whole has such a thickness that it is not ideal for laying directly on top of the ground surface, and it is usually necessary to provide a shallow excavation enabling the tiles to be sunk into the ground. This is normally done so that the tile surface is level with the surrounding ground. The need for the ground to be prepared in this way is a drawback, especially if the tiles are to be laid at an already existing playground. The enhanced energy absorption is achieved by the projections which on impact become progressively compressed in the direction of their length.
The present invention has for its broad aim to eliminate, or at least significantly reduce the disadvantages of the known tiles as elucidated above.
According to the present invention there is provided a surface tile, particularly for playground surfaces, the tile being formed of resiliently deformable material and comprising an upper sheet and integral projections in the form of hollow cylinders open at the lower ends thereof extending from the underside of the sheet, the projections being capable of collapsing by buckling under an impact against the upper surface of the sheet thereby to cushion the impact characterised in that the length of the projections is substantially less than the diameter thereof.
By the projections being designed to buckle, the same energy absorption performance can be achieved with projections of much shorter length than the projections used in the prior art tiles, and without forfeiting the support given to the sheet under normal loading.
In a preferred construction the projections are arranged in a regular array with their centers located at the corners of a pattern of squares.
A fixing member may be provided for fixing the tile to an underlying surface, the fixing member comprising a first part adapted to be fixed securely to the ground and a second, annular part for engaging a projection on the underside of the tile to attach the tile securely to the ground.
In a preferred embodiment the tiles have part projections at the edges thereof, and the fixing member is capable of engaging part projections of adjacent tiles for holding the tiles in close abutment as well as fixing them to the ground. The engaging part, and possibly the tile projection can be provided with a locking tooth-like projection. The first part may be adapted, e.g. by the provision of holes, to be fixed to the ground by bolts or other fasteners.
By use of separate fixing members the tiles can be fixed securely in position for normal purposes, but they are easier to replace and easier to lay than tiles stuck down with adhesive.
An edge strip may be provided for use with the surface tile of the invention, the strip being of a similar material to the tile and being arranged to be fixed against a free edge of the tile to provide a transition between the tile and an adjacent ground surface. One feature of the preferred edge strip resides in each end thereof being angled substantially at 135^o to the inner edge of the strip, and having areas of reduced thickness defining lines along which the strip can be cut, said lines extending at angles of substantially 90^o and 45^o, respectively, to the inner edge. With such an edge strip the same strip can be used, by severing the end along a cut line if necessary, to form a straight connection between an internal corner or an external corner with an adjacent edge strip. Another feature of the preferred edge strip resides in an outer edge portion normally projecting beyond the lower face of the strip, whereby the edge portion is stressed into abutment with the ground when the edge strip is fixed to the ground. The stressing of the edge portion helps prevent gaps, e.g. if the ground is not perfectly flat, and to prevent articles being forced under the edge.
A better understanding of the invention will be had from the following description, given with reference to the accompanying drawings, in which:-

Figure 1 shows in plan view a tile layout;
Figure 2 is a perspective view of one tile;
Figure 3 is an underneath view of the tile;
Figure 4 is a section taken along the line IV-IV in Figure 3;
Figure 5 is a plan view of a tile ground fixing member;
Figure 6 is a side view of the fixing member;
Figure 7 is a section taken along the line VII-VII in Figure 5;
Figure 8 is a sectional view showing the engagement of the fixing member with two tiles;
Figures 9, 10 and 11 show in plan, side and end view, respectively, a tile edge strip;
Figure 12 shows in end view an alternative edge strip;
Figure 13 is an underneath view of a modified tile for use in a cavity installation;
Figure 14 is an enlarged view showing a corner part of the tile in Figure 13;
Figures 15, 16 and 17 are sections taken along the lines XV - XV, XVI - XVI and XVII - XVII, respectively, in Figure 14;
Figure 18 is a plan view of a ground fixing member for use with the tile of Figure 13; and
Figures 19, 20 and 21 are sections taken along the lines XIX - XIX, XX - XX and XXI - XXI, respectively, of Figure 18.

Illustrated in Figure 1 is a playground tile layout, the tiles being laid on the top of a level ground surface. As shown there are five tiles 1 of identical construction to each other. Extending around the tiles is a continuous ramp edge or square edge formed from identical edge strips 2 as will be described in more detail below. The tiles and edge strips are fastened securely to the ground by ground fixing members located at the positions indicated by the letters A and B in Figure 1.
Each tile 1 is formed as a rubber moulding and as may be seen from Figures 2 to 4 has a generally flat upper sheet 4 from the underside of which extend projections 5 arranged in a regular array. The projections consist of hollow cylinders open at their lower ends and arranged with their centres at the corners of a pattern of squares. Half-projections are located at the tile edges, with quarter projections at the corners, the arrangement being such that each tile edge has the same appearance as the other three edges. When two tiles are placed together the half-projections combine to form complete cylindrical projections, and when the corners of four tiles are placed together the quarter-projections define a complete cylinder, as will be apparent from Figure 1. The tile may have a thickness of around 50 mm with the upper sheet having a thickness of about $\frac{1}{2}$
to $\frac{1}{3}$
the length of the projections. The diameter of the projections is substantially greater than, e.g. 2 to 3 times, their length. Under normal loads the projections 5 provide firm support for the sheet 4, but the walls of the projections can buckle under a shock loading to cushion the impact and provide gradual energy absorption.
A moulded rubber edge strip 2 is shown in detail in Figures 9 to 11. It includes half cylindrical projections 7 along its inner edge, arranged to register with the half-projections of a tile 1 against which the edge strip is located, and a downwardly sloping side wall 8 for providing a gradual transition from the top surface of the adjacent tile to the surrounding ground surface. Each end of the strip is inclined to the inner edge at 135^o, so that two strips can be positioned against adjacent edges of a tile and define a continuous ramp surface around the external corner e.g. as indicated at positions X in Figure 1. At each end the strip 2 is moulded with V-grooves 9, 10, or the like, extending along lines at 90^o and 45^o to the inner edge. These V-grooves define predetermined cut lines. Two strips cut along grooves 9 can be laid in a straight line, as indicated at positions Y in Figure 1, and two strips cut along grooves 10 can define an internal corner ramp section as indicated at Z in Figure 1. Thus only one form of strip is needed to provide a continuous ramp edge around a tile layout, whatever the perimeter shape.
The side wall 8 includes a wedge shaped free edge portion 12 which projects beyond the lower face of the edge strip 1, so that when the strip is fixed to the ground the portion 12 is stressed and presses down against the ground. This ensures that the edge fits tightly against the ground to prevent ingress of dirt under the edge strip and prevents articles being pushed under the edge strip. If required the undersurface of the edge portion 12 can be affixed to the ground with adhesive.
An alternative form of edge strip is shown in Figure 12. It differs from that of Figures 9 to 11 in that it has a vertical outer side wall 13 instead of a sloping wall. This strip is intended to be used when the tiles are to be recessed into a cavity and it obviates the need for a surrounding timber or concrete up-stand which would otherwise be required.
The tiles 1 and edge strips 2 are secured to the ground by ground fixing members 15, one of which is shown in Figures 5 to 7. It can be formed as a plastics or hard rubber moulding and consists of an annular base 16 with an upstanding circular rim 17 having an internal diameter to make a tight fit around the tile projections. On the inside of the rim a locking tooth 18 is provided for gripping the projection. The base includes a pair of projecting lugs 19 with holes 20 intended for bolting the member to the ground. After the member 15 has been fixed to the ground a tile projection is forced down into the rim 17 to fasten the tile securely to the around. As many fixing members may be used for each tile (up to the total number of projections 5) as may be considered appropriate, but a few located at suitable positions should be adequate. Some members 15 may be used merely to hold adjacent tiles together, such as that at position B in Figure 1, without being fixed to the ground. The fixing members shown at positions A in Figure 1 are bolted to the ground. They are located at the tile edges and they engage the co-operating part projections of the edge strips and tiles for securing both to the ground. Although the tiles and edge strips are held very securely by the fixing members they can be forced away, e.g. for replacement of a damaged tile. A fixing member is shown in Figure 8 engaged with projections of two abutting tiles. As well as fixing the tiles to the ground the fixing member holds them in tight abutment.
The modified tile illustrated in Figures 13 to 17 differs to that of Figures 2 to 4 in that it has a peripheral skirt 30 depending from the upper sheet, the depth of the skirt being substantially less than the length of the projections, and cruciform webs 31 interconnecting the four projections centred at the corners of each square. The webs stiffen the upper ends of the projections to improve the energy absorbing characteristics and the skirt helps prevent sharp tools being forced between and under the tiles in an unauthorised attempt to remove them. Furthermore, the projections 5 are tapered at their lower ends to facilitate insertion into the gripping members, and are provided with peripheral grooves 33 to assist their locking engagement in these members. Four uniformly spaced notches 34 are provided in the bottom of each projection for accommodating radial spokes 36 of the modified ground fixing member which is shown in Figures 18 to 21. In addition to the base 16 and upstanding rim 17, the fixing member has a frusto-conical hub 37 which is located centrally within the rim and connected to it by the spokes 36. To give extra stiffness to the lugs 19, they are formed with upstanding edges 38 which are joined to the rim 17. When a cylindrical projection 5 is forced down into the annular space defined between the hub 37 and the rim 17, the inner edge of the projection engages the conical surface of the hub, causing the projection to be expanded so that the rim tooth 18 engages securely in the groove 33 to ensure a very firm attachment.
From the foregoing it will be understood that when laying the tiles the fixing members 15 are fixed to the ground by bolts or pins using conventional techniques and then the tiles 1 and edge strips 2 (after appropriate trimming of the strip ends) are simply pressed down into position. No special measures are needed to ensure that the tiles and strips abut tightly at the joints. Because the lugs 19 are confined to one half of the member 15, it is also possible for a fixing member to be anchored to the ground after a tile edge projection has been engaged with the member, which assists location of the member prior to fixing.

Claims

A surface tile (1), particularly for playground surfaces, the tile being formed of resiliently deformable material and comprising an upper sheet (4) and integral projections (5) in the form of hollow cylinders open at the lower ends thereof extending from the underside of the sheet, the projections being capable of collapsing by buckling under an impact against the upper surface of the sheet thereby to cushion the impact characterised in that the length of the projections (5) is substantially less than the diameter thereof.
A tile according to claim 1, wherein the length of the projections (5) is 2 to 3 times the thickness of the sheet (4).
A tile according to claim 1 or 2, wherein the projections (5) are arranged in a regular array with their centres located at the corners of a pattern of squares, the distance between the centres of adjacent projections (5) being several times smaller than the length of the tile edges.
A tile according to any one of the preceding claims, wherein integral reinforcing webs (31) interconnect the projections (5) at the upper portions thereof.
A tile according to any one of the preceding claims, wherein an integral skirt (30) depends from the sheet (4) around the peripheral edge of the tile, the depth of the skirt being substantially less than the length of the projections.
A tile according to any one of claims 1 to 5, in combination with a fixing member (15) for fastening the tile to an underlying surface, said member having means (19, 20) for fixing the member securely to said surface, and a substantially annular part (17) for engaging a projection (5) of said tile to attach the tile securely to the ground.
A tile according to claim 6, wherein said substantially annular part is dimensioned to embrace tightly the projection and is provided with means (18) for gripping the projection.
A tile according to claim 7, wherein said gripping means comprises a locking tooth (18) and the projection has a peripheral groove (33) for cooperation with said tooth.
A tile according to claim 7 or 8, wherein the fixing member includes a hub portion (37) arranged to enter the tile projection (5) and to hold the projection in firm engagement with said gripping means (18).
A tile according to any one of claims 6 to 9, wherein the lower end of the projection (5) is tapered to facilitate insertion into the fixing member.
A tile according to any one of claims 6 to 10, wherein said substantially annular part (17) of the fixing member is integral with an annular base (16), and the fixing means comprises at least one lug (19) projecting from the base (16) and having a hole (20) for securing the lug to the underlying surface with a fastener, such as a bolt, inserted through the hole.
A tile according to any one of claims 6 to 11, wherein the tile is formed with part projections (5) at the edges thereof, and the fixing member (15) is engagable with part projections of two such tiles laid side-by-side for holding said tiles in close abutment and for fixing said tiles to said underlying surface.
A tile according to any one of the preceding claims wherein a separate edge strip (2) is provided in combination therewith and is positionable alongside the tile to form a transition between the upper surface of the tile and an adjacent ground surface, the edge strip being made of resiliently deformable material.
A tile according to claim 13, wherein the ends of the edge strip are at an angle of substantially 135^o to the inner edge thereof, and each end can be cut off at an angle of 90^o or 45^o to said inner edge, if required.
A tile according to claim 14, wherein the edge strip is provided with means (9; 10) to indicate the lines of cut at 90^o and 45^o.
A tile according to any one of claims 13 to 15, wherein the edge strip defines a ramp surface (8), the lower edge portion (12) projecting beyond the underface of the edge strip whereby the edge portion is stressed to abut firmly against an underlying surface when the edge strip is fixed to said surface.
A tile according to any one of claims 13 to 16, wherein the tile has part projections (5) located at the side edges thereof, and the edge strip is provided with complementary part projections (7) at the inner edge of said strip and arranged to register with the part projections of the tile, whereby a fixing member (15) may embrace said part projections (5, 7) to hold the tile and edge strip in close abutment and for securing them to an underlying surface.
A tile system for a playground surface, comprising several tiles (1) each as claimed in claim 1, and laid edge-to-edge to form a continuous surface and being secured to the ground, and a border arranged to extend continuously around the tiled area to form a transition from the tiled surface and the surrounding ground surface, characterised in that semi-cylindrical projections are formed at the edges of the tiles, said border is formed from identical edge strips (2) laid alongside the free edges of the tiles, the edge strips being of similar resiliently deformable material to that of the tiles and also being provided with semi-cylindrical projections (7) registering with respective semi-cylindrical projections of the tiles adjacent thereto, and said edge strips (2) and adjacent tiles are secured to each other by fixing members (15) embracing tightly pairs of registering semi-cylindrical projections and optionally fastened to the ground.