WO2017081462A1

WO2017081462A1 - Channel section for forming a drainage channel and method of rotational moulding a channel section

Info

Publication number: WO2017081462A1
Application number: PCT/GB2016/053506
Authority: WO
Inventors: Christopher Mark LAMB
Original assignee: Marshalls Mono Limited
Priority date: 2015-11-13
Filing date: 2016-11-09
Publication date: 2017-05-18
Also published as: GB2544349B; GB2544332A; GB2544332B; GB201521212D0; GB2544349A; GB201520067D0

Abstract

Improved High Capacity Drainage Channel There is provided a channel section 10 having a plurality of slot apertures 30 that extend from a longitudinally extending pipe section 20 discontinuously, wherein the slot apertures are arranged so that a portion of each adjacent slot aperture is spaced offset perpendicularly across the longitudinal direction of the pipe section. Advantageously therefore, an aperture is formed to collect water across the entire longitudinal length of the channel section, but each slot aperture is discontinuous in the longitudinal direction and spaced from adjacent slot apertures allowing passages for rebar36. Here, the rebar 36 is arranged in the passages at a slanted angle across the pipe section. Channels may be formed in the passages to receive the rebar. Here, the channels may be grooves formed in the outside ofthe pipe section. The channel section may have an end with a double walled section. The double wall section provides a delimited wall having a free end spaced from the distal end of the channel section. Here, the delimited wall is able to be more deformable than the other wall and therefore provides flexibility in the connection. There is also provided a method of rotational moulding a channel section wherein a blank wall that is removed to create the channel section is able to be arranged on a planar face, even when the end has a complex shape.

Description

CHANNEL SECTION FOR FORMING A DRAINAGE CHANNEL AND METHOD OF ROTATIONAL

MOULDING A CHANNEL SECTION

FIELD

[01 ] The present invention relates to an improved drainage channel for draining surface water into a buried channel, and in particular to a component for forming a high capacity drainage channel.

BACKGROUND

[02] High capacity drainage channels are known for draining surface water from large surface areas such as car parks, highways, airports, warehouse loading bays, driveways, or any other large area of hardstanding concrete/tarmac that will generate large amounts of surface water. The water is drained into a buried channel structure sometimes called a slot drain or linear slot drain. Here, the surface typically includes at least one incline so that surface water runs from the surface in a particular direction. The drainage channel is arranged across, and generally perpendicularly across, the incline to collect the surface water and move it away to an appropriate discharge or collection point.

[03] EP1380691 discloses a known high capacity drainage channel formed from a plurality of adjacent channel sections. The channel sections are moulded plastic components and are buried in the substructure of the surface to drain surface water. Each channel section comprises a longitudinally extending pipe section for forming a buried channel into which the surface water is drained. The surface water enters the pipe section through a plurality of projections that interconnect a surface channel with the pipe section. The projections and top channel form a series of arches through which rebar is arranged to support and strengthen the sub structure.

[04] The drainage channel is formed by arranging a plurality of the channel sections within a surface substructure. Each section can be secured to each other and sealed as is known in the art. Appropriate rebar reinforcement is arranged and the surface overlaid to typically level with the top channel. An additional decorative cover can be placed in or over the top channel. Water on the surface is drained through the top channel and moved away to an appropriate discharge location.

[05] The hollow arches formed by the projections and top channel allow apertures for the rebar, whilst also forming a continuous channel in the surface to drain the full width of the surface. However, moulding the arches complicates the moulding process. Furthermore, the top channel also requires sealing to adjacent top channels.

[06] It is an object of the present invention to attempt to overcome at least one of the above or other disadvantages. It is a further aim to provide a channel section that can be more easily moulded or moulded more efficiently. It is a further aim to provide a channel section providing an increased drainage capacity. It is a further aim to provide an alternative to the known high capacity drainage systems.

SUMMARY

[07] According to the present invention there is provided an improved channel section for a high capacity drainage channel and a method of rotationally moulding the same as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows.

[08] In exemplary embodiments there is provided a channel section having an end formed from a double wall section. The double wall section has a first wall and a second wall that are spaced apart from each other. Suitably, the first and second walls are formed to be generally parallel. The first and second walls are connected at a distal end by an end wall. One of the walls forms a part of a main body of the channel section. The other wall extends a delimited extent along the other wall, wherein a distal end of said wall is not joined to the other wall. Advantageously, the delimited wall is able to flex at a join between the two walls. Here, the flexing creates a wall that is more deformable than the other wall that necessarily has to have a degree of rigidity to prevent the channel section collapsing in use. This increased deformability provides an improved connection when a second channel section is connected in a male-female relationship with the double walled end. It will be appreciated that the advantageous double walled-end profile is useable with channel sections with or without incorporating the herein referred to features of the channel section including continuous or discontinuous slots.

[09] In the exemplary embodiments, the end of the channel section having the double walled section has a complex shape. That is, the distal end is not arranged to be a planar face. Preferably, the channel section is elongate, and laid in an end to end fashion wherein the elongate channel sections form an elongate drainage channel. Here, the non-planar ends extend in a generally planar extent in an axial direction, with complex shapes formed in the axial direction such as notches and cut-outs to accommodate parts of the adjacent channel section, and as will be herein described to obtain a constant aesthetic to the installed and joined channel sections.

[10] In the exemplary embodiments, suitably the delimited wall section extends at least the distance of the non-planar end section. That is the double walled section extends from the distal end of the channel section a length at least as far as the distal end remains non-planar. That is at least as far as any notches or cut-outs. Preferably, the first and second walls are only connected to each other at the distal end face of the channel section.

[1 1 ] In the exemplary embodiments, the double walled section is formed on one end of the channel section. However, it may be formed on both ends as appropriate for the situation. The delimited wall may be formed outside the main wall. Here, the distal end would be a male end, wherein a female end of an adjacent channel section fits over the distal end. However, in the exemplary embodiments, the delimited wall is shown as being an inner wall. Here the end forms a female end that receives a male end of an adjacent channel section. In the exemplary embodiments, the delimited wall is arranged to lie adjacent a more rigid wall of an adjacent channel section. A seal is typically arranged between the faces, such as a resilient ring seal. In use, the delimited wall is able to deform to adapt to any imperfections in the shapes of the male or female ends such that an improved connection is realised.

[12] In a further exemplary embodiment there is provided a method of forming a channel section as described above. The method comprises moulding or casting the channel section. Here, the end of the channel section is formed into the desired shape with a blank closing the end of the channel section. The method comprises removing the blank, for instance by cutting or machining. Because the blank is provided spaced from an end of the channel section, wherein the double walled section forms an overhanging ring, the blank can be arranged to be planar. Consequently, the removal of the blank is simplified. Alternatively, the blank would have a complex, non-planar shape, or the notches or cut-outs in the end would have to be machined as a further process.

[13] Although the channel section may be moulded or cast through a number of processes, the method is particularly useful for rotational moulding. Here, a plug mould is used at the double walled end wherein the plug forms the overhang section with the rotational moulding process coating the faces of the plug section as well as the faces of a main mould. An internal end face of the plug mould is planar and forms the blank closing the channel section and that is removed after moulding. Suitably, the method comprises withdrawing the plug mould from the formed channel section before removing the blank.

[14] In exemplary embodiments, the channel section comprises a plurality of slot apertures that extend from a longitudinally extending pipe section discontinuously, wherein the slot apertures are arranged so that a portion of each adjacent slot aperture is spaced offset to another perpendicularly across the longitudinal direction of the pipe section. Here, the longitudinally pipe section forms the main body and a distal end of the pipe section is said end having a double wall. Advantageously therefore, an aperture is formed to collect water across the entire longitudinal length of the channel section, but each slot aperture is discontinuous in the longitudinal direction and spaced from adjacent slot apertures allowing passages for rebar. Here, the rebar is arranged in the passages at a slanted angle across the pipe section. Channels may be formed in the passages to receive the rebar. Here, the channels may be grooves formed in the outside of the pipe section. It will be appreciated that the advantageous slot arrangement is useable with channel sections with or without incorporating the herein referred to features of the double end-wall design. [15] Each of the plurality of slot apertures may comprise a first part integral to the pipe section and a second removable part. The removable part acts a plug to prevent building materials from entering the pipe section during construction of the drainage channel. Once installed, the plug is removed. In one exemplary embodiment, the finished surface is a cementitious product such as concrete or other material able to be cast. Here, the material can be cast around the second removable part as well as the first part. Advantageously, when the plug is removed, the first part may be spaced beneath the top surface of the finished surface so that traffic, such as vehicular traffic, does not contact the channel section directly. This is advantageous because the channel section may not have the required structural characteristics to satisfy loading requirements. The removable part may be designed to cast further shapes, patterns or features into the finished surface. For instance, the removable part may be shaped to provide a flare or rounded corner to the opening of the finished cast substrate. Additionally or alternatively, the removable part of each slot aperture may be joined to adjacent removable parts so that the plugs can be removed as a single piece. Here the joining parts may be adapted to mould features such as a drainage indent between slot apertures. Alternatively, the drainage indent may be cut or machined into the finished surface as a later process.

[16] The portions of each slot aperture that are spaced offset perpendicularly across the longitudinal direction of the pipe section includes at the extreme, the adjacent slot apertures terminating at the same perpendicular plane across the pipe section. Advantageously however adjacent slot apertures overlap one another. That is, the end of one slot aperture terminates at a perpendicular plane across the pipe section that intersects an adjacent slot aperture. This overlap may be at least 10% or at least 20% of the distance said slot aperture extends in the longitudinal direction. The overlap may be less than 50% or less than 40% of the distance said slot aperture extends in the longitudinal direction.

[17] Preferably, each slot aperture is substantially identical. A consistent and repeatable appearance of apertures is therefore provided in the finished surface. As will be appreciated, the appearance of the aperture in the finished surface will be formed around the slot aperture and can therefore be altered for different aesthetics by altering the profile of the slot apertures. Suitably, each slot aperture comprises an upwardly extending protrusion from the pipe section. The cross-sectional profile of each slot aperture may taper so as to reduce towards a distal end. This helps reduce the risks of blockages. Each slot aperture is sized so as to extend from the pipe section to the top surface of the area being drained. Each slot aperture is substantially identical. The shape of each slot aperture may vary, but in the exemplary embodiments the slot apertures are shown as elongate. Suitably with a rectangular cross section. Rounded corners and usual moulding release features may be incorporated as is known in the art.

[18] Suitably, the channel section is moulded from a plastic material. The discontinuous slot apertures and drainage section can be moulded from a single moulding. The walls of the moulding may have a substantially constant thickness. [19] Preferably, the plurality of slot apertures each extends parallel to the longitudinal axis of pipe section. Here each of the plurality of slot apertures is formed in at least two rows. Each row is off-set to the other. That is, the pitch of the slot apertures in each row is arranged so that the centre between each slot aperture is not aligned with adjacent slots in the other row. Here, the passage for the rebar is formed diagonally across the longitudinal axis of the pipe section wherein the rebar is arranged between the slot apertures.

[20] Alternatively, the plurality of slot apertures extend from a longitudinally extending pipe section arranged at an angle to the longitudinally extending pipe section. The angle slants the respective slot aperture across the longitudinal axis of the pipe section. In the exemplary embodiments, the slot apertures are angled around 45° to the longitudinal axis. However, the slot apertures may be angled between 40° and 50° or between 30° and 60°.

[21 ] Webbing may be provided between adjacent slot apertures. The webbing reinforces the slot apertures. In the exemplary embodiments including retaining channels for the rebar, the channels may be formed by valleys of the webbing.

[22] Preferably, the drainage channel includes reinforcement features. Here the reinforcement features are bands. Each slot aperture may extend between at least two bands.

[23] Advantageously, each slot includes a key portion. Here, the key portion acts to resist the slot collapsing away from the cast material. In the exemplary embodiments, each slot includes a plurality of key portions. Suitably, the plurality of key portions comprise a first and second opposed key portions, wherein the first and second opposed key portions are formed on opposed sides of the slot. Suitably, the key portions extend away from the slots and in a direction angled to the extent of the slot. Each key portion forms a recess for receiving cast surface material, wherein the recess is formed between a part of the key portion and the slot. In one exemplary embodiment, the key portion is a pocket. Here, the pocket is open to a top of the unit. Alternatively, the key portion comprises a hook or barb. Here the hook has a dimension in a direction aligned to the slot, wherein the surface material is cast around the hook or barb.

[24] One end of the drainage channel may comprise a male end and the other a female end. Here, the male and female ends are fitted within each other to connect a plurality of drainage sections to form the drainage system. Each of the male and female ends may include outwardly extending flanges. Upper and lower respective surfaces of the flanges may contact in use to provide support to the joint between the two sections in a downwardly loading direction, wherein the downwardly loading direction corresponds to the loading direction of traffic across the surface to be drained. The flanges may be drilled to receive securing pins or the like.

[25] According to the exemplary embodiments there is provided an improved channel section for a high capacity drainage channel, wherein the moulding of the channel section is improved but wherein the entire width of the surface is drained and rebar is able to be arranged across the channel.

[26] There is also provided an improved method of installing a drainage channel. The method comprises installing a first channel section as described above and including a removable plug, forming a surface structure around the channel section and removable plug, removing the removable plug so that the first part of the slot drain is spaced beneath the finished surface level, wherein the removable plug acts as a mould to impose a shape to the surface structure.

[27] Accordingly, in one aspect there is provided a channel section having a double walled end section formed from first and second overlapping walls, wherein the first wall has a free end spaced from a distal end of the channel section such that said first wall is more easily deformed than the second wall. Preferably the first and second walls are connected by a distal end wall, wherein the distal end wall forms the end of the channel section and the first wall is delimited by the free end is not otherwise attached to the second wall. Preferably the end of the channel section has a complex shape including a notch that extends inwardly from the distal end wall and in an axial direction of the channel section. Preferably the delimited first wall is internal to the second wall, and such that the end forms a female connector for receiving a male end of an adjacent channel section. Preferably the other end of the channel section forms a male connector. Preferably the double wall end section encompasses the notch. Preferably both the first wall and the second wall form a substantially continuous band.

[28] Accordingly, in one aspect there is provided a method of rotational moulding a channel section having a double walled end section as claimed in any of claims 1 to 7, the method comprising forming a main mould and inserting a plug mould into one end so that an end face of the plug mould forms a planar blank face spaced from an end of the channel section, carrying out a rotational moulding process, and subsequently removing the planar blank face to create the channel section having a double walled end section formed from first and second overlapping walls, wherein one of the first walls has a free end spaced from a distal end of the channel section such that said first wall is more easily deformed than the other second wall, and wherein one of the first and second walls are formed during the rotational moulding against a face of the main mould and the other of the first and second walls are formed during the rotational moulding against a face of the plug mould. Preferably the end of the channel section includes a complex shape having a notch that extends inwardly from the distal end wall and in an axial direction of the channel section.

[29] Accordingly, in one aspect there is provided a method of forming a drainage channel, the method comprising connecting a first channel section to a second channel section, wherein each channel section is as claimed in any of claims 1 to 7 and wherein the method comprises causing a delimited wall of the double wall section of one of the channel sections to deform in order to accommodate an end of the other channel section. [30] Accordingly, in one aspect there is provided a channel section for forming a drainage channel, the channel section comprising an longitudinal pipe section and a plurality of slot apertures, wherein each slot aperture extends from the pipe section to form a discrete aperture spaced from the pipe section, each slot aperture being discontinuous in the longitudinal direction, with a portion of one adjacent slot aperture being spaced perpendicularly across the longitudinal direction of the pipe section to a portion of the another slot aperture. Preferably each slot aperture is arranged slanted across the longitudinal direction of the pipe section, and each slot aperture is arranged parallel to an adjacent slot aperture and spaced along the longitudinal direction. Preferably an outer surface of the pipe section in a passageway between adjacent slot apertures includes a channel for receiving rebar. Preferably the pipe section includes reinforcing bands, each slot aperture extends across first and second bands, and wherein the channel for receiving the rebar is formed in the band crossing between adjacent slot apertures. Preferably a web is formed between adjacent slot apertures and the web is formed with a valley for locating rebar. Preferably one end of the channel section forms a male end and the other forms a female end, the male end including an insertion section that is suitable for insertion into a female end of a further channel section. Preferably, each end includes a sideways extending flange, and an upper surface of one flange is arranged, when the channel section is coupled to another channel section, to face a lower surface of the corresponding other flange on the other channel section. Preferably a separable plug covering the slot apertures is provided. Preferably the channel section is plastic.

[31 ] Accordingly, in one aspect there is provided a channel formed from a plurality of channel sections wherein each channel section is as herein described. Preferably ends of each channel section includes a sideways extending flange, and an upper surface of one flange is arranged, when the channel section is coupled to another channel section, to face a lower surface of the corresponding other flange on the other channel section.

[32] Accordingly, each aspect is useable on its own or in combination with one or more of the other aspects

BRIEF DESCRIPTION OF DRAWINGS

[33] For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which:

[34] Figure 1 is a perspective view of a channel section according to a first embodiment;

[35] Figures 2a and 2b are top and end views of Figure 1 ;

[36] Figure 3a and 3b show exemplary, alternative configurations for slot apertures; [37] Figure 4 is a perspective view of Figure 1 showing the channel section with rebar installed;

[38] Figure 5 is a perspective view of the channel section of Figure 4 showing an installed top surface;

[39] Figure 6 is a perspective, side and top view of a channel section according to a second embodiment;

[40] Figures 7a and 7b are perspective and side views of a further embodiment;

[41 ] Figure 7 shows a perspective view of a channel section embodiment with laid top surface;

[42] Figure 8 shows a perspective view of a channel section embodiment embedded in a ground structure; and

[43] Figures 10 and 1 1 show top and perspective views of alternative embodiments of a channel section;

[44] Figures 12a and 12b are top and side schematic cross sectional views of a channel section being formed;

[45] Figure 13 is an end view of a de-moulded channel section;

[46] Figure 14 is a cross section view through an end of a channel section; and

[47] Figure 15 is a perspective view of an exemplary slot design.

DESCRIPTION OF EMBODIMENTS

[48] Referring to Figure 1 , a channel section 10 is shown. The channel section 10 comprises a pipe section 20 and a plurality of slot apertures 30. The channel section is installed within a trench so that the channel section is substantially completely buried in the final surface. A sub structure of a ground covering is placed around the channel section and rebar arranged across the top of the pipe section in order to stabilise and spread loading through the sub structure. A final surface is laid over the channel section so that the ends of the slot apertures are substantially level with a top of the end surface. The slot apertures 30 provide drainage from the top surface into the pipe section 20. When installed, a plurality of the channel sections are joined to form a drainage line across the surface. The slot apertures are formed discontinuously along the length of the drainage channel. Here, water urged to drain across the top surface and perpendicular to the drainage line will be caught by a slot aperture. However, an angle slanted to the drainage line can be taken that does not intersect a slot aperture.

[49] Referring still to Figure 1 , the pipe section 20 comprises an enclosed passageway for collecting and transporting the drained surface water. The pipe section has a longitudinal axis defined generally in the length direction of the channel section. The length and general sizing of the pipe section will be dependent on the use and capacity of the moulding process but is generally to be a similar size as is known in the art. The pipe section may have any known cross sectional shape, but is shown in the figures with a semi-circular upper section 12 and a lower section having tapered walls 13 that taper to a rounded end 14. Feet 15 are provided to assist the location of the channel section 10 during installation as is known in the art. The feet 15 are shown suitably arranged spaced from ends of the channel section.

[50] As is shown in Figure 2a, bands 17 or ribs are provided at regular spacing along the longitudinal length of the pipe section 20. These bands comprise outward projections that ring the pipe section. This provides strength to the channel section to withstand the anticipated loading and to prevent the pipe section buckling or deforming under load. The bands 17 are shown as having a consistent wall thickness to intermediate parts 18 between bands.

[51 ] The channel section 10 is shown with longitudinal ends 40, 50. In the exemplary embodiments, the ends 40, 50 are arranged as male and female ends so as to locate with respective opposed male and female ends of other channel sections when connected together to form the drainage system. Referring to Figure 1 , end 40 is shown as a male end and end 50 a female end. Here, two channel sections 10 are connected to each other by inserting a male end into a female end. Suitably, male end 40 includes an insertion section 42 that extends from the end in a longitudinal direction and is sized so as to locate inside the female end (see also Figure 7a). By locating the insertion section inside the female end 50, the joint is supported to act against the two sections becoming misaligned and particularly to assist in maintain the coaxial alignment. Each male and female end is shown as having an outwardly extending flange 44, 54. Suitable, a flange extends from each side of the pipe section 20. The flanges extend outwardly, perpendicularly across the longitudinal direction when viewed in plan. Here, as the two channel sections are connected by relative movement in the longitudinal direction so as to insert the male end into the female end, the respective flanges pass over each other. Therefor an upper and lower surface of each flange on opposed sections abut each other in a downwardly loading direction. The flanges may be mechanically secured together. In use, the abutment between the upper and lower respective surfaces of the flanges, supports the joint and assists in preventing relative movement between the two channel sections.

[52] As will be herein described, the channel sections are suitably moulded plastic sections. Whilst the channel section can be moulded in multiple parts, suitably, the channel section is shown as being a single piece moulding. The exact shape of the moulded channel section may therefore be optimised for the moulding process as is known in the art.

[53] The channel section is shown with a plurality of slot apertures 30. The slot apertures extend upwardly from the pipe section 20 to provide a plurality of discrete drainage locations. Each slot aperture is formed from side walls 32 and end walls 34. The walls have a substantially constant thickness. Each aperture has a substantially elongate cross section and is generally shown as being a thin rectangle. The end walls 34 are shown as being rounded. [54] In the exemplary embodiments, the slot apertures 30 are discontinuous in the longitudinal direction of the pipe section 20. As shown in Figure 3a, one exemplary embodiment shows the slot apertures formed in two rows. Each row extends in the longitudinal direction and are spaced from each other. Further, each row of slot apertures 30 comprises a plurality of slot apertures. The slot apertures are suitably regularly spaced. The slot apertures in each row are off-set from each other so that the centre between adjacent slot apertures 30 in one row is not aligned with the centre between adjacent slot apertures in the other row. Thus, as shown by dotted line, a passageway is formed slanted across the channel section for receiving rebar. The passageway is formed by the spaces between adjacent slot apertures in each respective row. As shown in Figure 3a, the slot apertures are discontinuous in the longitudinal direction to thereby define the discrete slot apertures 30. However, the slot apertures are arranged so that a portion of each adjacent slot aperture is spaced offset perpendicularly across the longitudinal direction of the pipe section. Thus water running on the surface perpendicularly to the longitudinal direction will be drained by a slot aperture, but leaving aperture free zones along a slanted path.

[55] Figure 3b shows an alternative configuration wherein each slot aperture 30 is arranged at an angle across the longitudinal direction of the pipe section 20. The drawings show the slot apertures angled at 45° but other angles are envisaged. Each adjacent slot aperture is parallel to the other and regularly spaced so as to provide a uniform appearance. Again, the slot apertures are arranged so that a portion of each adjacent slot aperture is spaced offset perpendicularly across the longitudinal direction of the pipe section. In this case, adjacent slot apertures include an overlap so that in some zones, wherein a zone is defined as an area along the longitudinal direction, include portions of at least two adjacent slot apertures. As shown in Figure 3b, zones Z1 and Z3 includes a portion of one slot aperture, whereas zones Z2 and Z4 include portions of at least two slot apertures. In contrast, Figure 3a shows the extreme situation wherein whilst all zones have a portion of at least one slot aperture zones Z2 and Z4 are linear or put another way the zone is infinitely thin. That is, the ends of adjacent slot apertures are aligned in a perpendicular line across the longitudinal direction. It will be appreciated that the size and spacing of the slot apertures can be altered to achieve the desired aesthetic look and functional capacity. However, whilst overlapping the slot apertures increases the drainage capacity, importantly, in both situations, water draining across the drainage channel will travel across at least one aperture, whilst because the slot apertures are discontinuous in the longitudinal direction, passages for the rebar are also provided without the need for the top drainage slot to be arched or formed over the rebar. A 2% overlap and a 50% overlap are exemplary approximate overlaps relative to the slot length based on general dimensions of known slot drainage sections.

[56] The channel section is installed substantially as the known systems discussed above. A detailed description therefore will be omitted. Nevertheless, when the loading requirements require the fitting of rebar, suitable rebar is laid over the pipe section. As shown in Figure 4, the rebar 36 is arranged in the passages between the adjacent slot apertures 30. Suitably, in order to assist the retaining of the rebar in position during installation, channels 37 are formed in an outside surface of the pipe section between the adjacent slot apertures. In the exemplary embodiments, the pipe section 20 is shown having the reinforcing bands 17 as described above and the slot apertures extend between at least two bands. Here, each channel is formed in the band at the midpoint between each adjacent aperture. The channel 37 is not formed all the way through the pie section so as to maintain the enclosure and so as not to create an opening for debris.

[57] The finished surface is formed around the channel section. Figure 5 shows a concrete floor cast directly around the slot apertures. However, other surface finishes are envisaged. Typically the slot apertures are plugged during installation to prevent debris falling in. Here the plugs are removed after installation. For instance, in Figure 7, plugs 60 are shown in place to cover the openings to the slot apertures.

[58] Referring to Figure 6, a further exemplary embodiment is shown. Here, webs 38 are formed between adjacent slot apertures 30. The webs structurally support the slot apertures. Shown as having a valley appearance, the webs include a valley for receiving the rebar. The valley of the webs therefore acts as the rebar slot at the centre of the passage between adjacent slot apertures. Suitably, as shown in Figure 7c, two webs are provided. Each web is parallel and spaced from each other. A recess 39 is formed or machined in the female end to receive a slot aperture of an adjacent channel section so as to maintain the consistent spacing of the slot apertures in the finished surface.

[59] Figure 7 shows a further embodiment depicting longer slot apertures for use with deeper sub bases. As mentioned, the length of each slot aperture is dependent on the required use. However, it will be appreciated that the slot apertures are substantially elongate in the upwardly extending direction. Typically the slot apertures might extend at least 3 or at least 5 times the width of the opening to the slot aperture.

[60] Figures 5, 8 and 9 show alternative channel embodiments embedded beneath a finished top surface 100. Figure 5, shows the finished top surface cast around the slot apertures so that the slot apertures are level with a top of the finished surface. However, it is preferable if the slot apertures do not extend to the top of the surface as this avoids forces being applied directly to the slot apertures and allows the structural characteristics of the finished surface to provide the strength to direct contact with traffic. As shown in Figure 8, the slot apertures may be installed with removable plugs. The removable plugs act as a continuation of the slot aperture and allow the surface material to be formed there around. The finished surface may be a cementitious product or other relatively fluid application that hardens. This allows the removable plugs to be removed, leaving an opening in the finished surface leading to the distal end of the slot aperture. Figure 9 depicts the finished surface with the drainage channel completely buried within the surface structures.

[61 ] Figures 10 and 1 1 show alternative embodiments of the drainage channel. The drainage channels are substantially as herein described. However, as can be seen from Figures 10a and 1 1 a, the slot channels are tapered. That is, the slot channel is wider at a base with the drain section than at a distal end. Furthermore, the distal apertures of the slot apertures are shown as having a generally elongate, rectangular profile, whereas the base of the slot aperture has a more round, oval profile. This tapering assists in preventing blockages from debris getting trapped in the slot aperture. It will be appreciated that different sized drainage channel sections are required. Figures 10 and 1 1 show two examples, but others are envisaged. As will be appreciated, the size and shape of the slot aperture defines the appearance of the slot drain in the finished surface and the shape and size may therefore be adapted accordingly.

[62] Referring to Figure 12, a channel section is suitably formed using a moulding or casting process. The preferred process is a rotational moulding process. Here, a material is deposited into a closed mould and the mould is typically simultaneously heated and rotated in order to cause the material to flow and coat the internal surfaces of the closed mould. Rotational moulding is a process known in the art and so a further detailed explanation is omitted. Once the material has coated the internal surfaces, the material sets and is demoulded. To form channel sections a blank formed across the ends of the pipe section need to be removed, typically by a cutting process.

[63] As shown in Figure 12a, a main mould 1 10 forms the mould for the channel section and is sized and shaped according to the desired channel section. It may be formed from a number of parts as is known in the art and in order to de-mould the formed section. A plug mould 120 is inserted into an end of the main mould 1 10, to space the blank face 41 c from a distal end of the channel section. Consequently, the end is formed to have a double walled section having a first wall 41 a and a second wall 41 b. The two walls are show as extending parallel to each other. Each wall forms a substantially continuous ring around the channel and are joined by an end wall 41 d. The inner wall 41 b is closed by blank wall 41 c. The plug mould is moveable to insert and withdraw from the main body and it will be appreciated that the plug mould is therefore withdrawn to allow the de-moulding process from the main mould.

[64] In order to achieve the constant overlapping of the channel sections, in the exemplary embodiment, it is necessary to have a non-planar end. That is the end of the channel section includes a notch or cut-out as shown in dotted line in Figure 12a. Here the plug mould is able to form the cut-out as part of the moulding process by appropriate shaping and as shown in Figure 12b. The double wall section overlaps at least the extent of the cut-out and preferably, as shown past the complex shape in order to maintain an inner rim at all points. Consequently, the blank face 41 c is able to be maintained as a planar face. [65] As shown in Figure 13, the blank face 41 c is required to be cut or otherwise removed to provide the channel section. As the blank face 41 c is planar, the removal process is simplified as compared to the situation where the main mould was shaped without an overlapping double walled section.

[66] Referring to Figure 14, once the blank face is removed the channel section is provided. Here, the channel section has an end having a double wall section. The double wall section is joined at the distal end by end wall 41 d. Here, because a free end is created at the termination, of the wall delimited by the removed blank face 41 c, the delimited wall is more easily deformable that the other wall that is required to be rigid to prevent collapse during use. The delimited wall flexes about the join at the distal end face 41 d. Consequently, an improved join is provided as when a male end is inserted into the female end having the double walled section, the delimited wall is able to deform to accommodate imperfections in the size and shape of the parts. Typically a seal would be applied between the two sections for instance a bead of silicone or a ring seal as is known in the art.

[67] Figure 15 shows an exemplary profile of a slot 300 design. It has been found that due to shrinkage of the cast ground material, which as explained above is typically a cementitious material such as concrete, the concrete compresses the slot whilst curing. Because of the elongate slot shape design, the effect of the shrinkage is most pronounced in the elongate direction. Therefore, it has been found that as the concrete shrinks, because the slot is constrained the side walls 320 tend to buckle or pull away from the cast concrete walls. Consequently, as shown in Figure 15, a key portion 350 is provided. The key portion 350 acts to lock the side wall 320 of the slot to the concrete when cast. Consequently, the key portion acts to restrain the side walls from pulling away from the concrete as the concrete cures and shrinks.

[68] In figure 15, the key portion is shown as a pocket, having an open top. The outer edge of the pocket forms a hook or barb that allows concrete to be cast between the pocket edge and the side wall of the slot allowing the slot to be hooked within the concrete. However, the key portion could be formed in other ways, for example a hook or barbed projections may be provided that extend away from the or each side wall of the slot, which when encapsulated by a cast surface layer, the hook or barbs are captured by the concrete wherein the hook or barb are arranged to restrict the hook or barb being pulled through the material towards the aperture.

[69] Advantageously, there is provided an alternative drainage system. Moreover, the channel section can be moulded efficiently.

[70] Although preferred embodiments) of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made without departing from the scope of the invention as defined in the claims.

Claims

1 . A channel section for forming a drainage channel, the channel section comprising an longitudinal pipe section and a plurality of slot apertures, wherein each slot aperture extends from the pipe section to form a discrete aperture spaced from the pipe section, each slot aperture being discontinuous in the longitudinal direction, with a portion of one adjacent slot aperture being spaced perpendicularly across the longitudinal direction of the pipe section to a portion of the another slot aperture

2. The channel section of claim 1 , wherein each slot aperture is arranged slanted across the longitudinal direction of the pipe section, and each slot aperture is arranged parallel to an adjacent slot aperture and spaced along the longitudinal direction.

3. The channel section of any preceding claim wherein an outer surface of the pipe section in a passageway between adjacent slot apertures includes a channel for receiving rebar.

4. The channel section of claim 3, wherein the pipe section includes reinforcing bands, each slot aperture extends across first and second bands, and wherein the channel for receiving the rebar is formed in the band crossing between adjacent slot apertures.

5. The channel section of claim 1 wherein a web is formed between adjacent slot apertures and the web is formed with a valley for locating rebar.

6. The channel section of claim 5, wherein first and second webs are formed.

7. The channel section of any preceding claim wherein one end of the channel section forms a male end and the other forms a female end, the male end including an insertion section that is suitable for insertion into a female end of a further channel section.

8. The channel section of claim 7, wherein each end includes a sideways extending flange, and an upper surface of one flange is arranged, when the channel section is coupled to another channel section, to face a lower surface of the corresponding other flange on the other channel section.

9. The channel section of any preceding claim including a separable plug covering the slot apertures.

10. The channel section of any preceding claim wherein the channel section is plastic.

1 1 . The channel section of any proceeding claim having a double walled end section formed from first and second overlapping walls, wherein one of the walls has a free end spaced from a distal end of the channel section such that said wall is more easily deformed than the other wall.

12. The channel section of claim 1 1 , wherein the first and second walls are connected by a distal end wall, wherein the distal end wall forms the end of the channel section and the wall delimited by the free end is not otherwise attached to the other wall.

13. A drainage channel formed from a plurality of channel sections wherein each channel section is as claimed in any preceding claim.

14. The drainage channel of claim 13, wherein ends of each channel section includes a sideways extending flange, and an upper surface of one flange is arranged, when the channel section is coupled to another channel section, to face a lower surface of the corresponding other flange on the other channel section.

15. A method of rotational moulding a channel section, the method comprising forming a main mould and inserting a plug mould into one end so that an end face of the plug mould forms a planar blank face spaced from an end of the channel section, carrying out a rotational moulding process, and subsequently removing the planar blank face to create the channel section.