The present invention relates to a measuring and positioning tool, particularly suitable for use when installing artificial grass.

BACKGROUND TO THE INVENTION

Artificial grass is typically supplied on 4-metre wide rolls, and so to create anything more than a very small artificial lawn, a join between two sections is likely to be required.

Artificial grass typically comprises strands of plastic “grass” yarn, stitched to a substantially flat backing sheet. The strands of grass are stitched in lines onto the backing sheet. When cutting a sheet of artificial grass where it will be joined to another sheet, it is important to ensure that the cut is made in a straight line parallel with the stitch lines, i.e. without cutting across a row of stitching.

To join the sheets of grass to each other, firstly they must be positioned correctly. The cut edges of the sheets to be joined have to be placed a precise distance apart, along the full length of the join. The correct distance ensures that the density of the strands of grass remains consistent and there is no visible join line in the finished installation. If the edges of the sheets are too close to each other, then there will be a higher density of strands along the join line. In the worst case, parts of the backing sheet may even overlap each other creating a ridge. On the other hand, if the edges are too far apart then there will be a visible gap in the finished artificial lawn.

Placing the two sheets of grass at the correct distance allows the appearance of the strands of grass to replicate the gauge between stitch lines, providing a substantially invisible join. The object is to maintain the gauge of the stitch lines across the join.

Once the sheets have been correctly positioned, the edges to be joined are folded over to allow a strip of joining tape to be placed beneath the join line.

Adhesive is spread onto the joining tape. The sheets of grass are then folded back over onto the joining tape, pressed down, and the adhesive is allowed to cure.

Nails can be used to temporarily hold the sheets in position while the sheets are folded over, and the tape is laid and adhesive is being applied. The nails may be driven through the grass sheets, for example along a line running about 30cm behind the join line. After the sheets of grass are folded back over the joining tape, fine adjustments can be made along the join line, for example to ensure that no strands of grass are trapped between the two sheets, and to ensure that the backing sheet is pressed flat against the joining tape all the way along the join line. However, the adhesive will cure quickly and even before the adhesive is cured, it will be extremely difficult if not impossible to correct any error in positioning the sheet as a whole.

Installers currently rely on estimating the correct position by sight. Experienced installers can get good at this so that they will usually achieve at least a good result. However, there is still inconsistency and even experienced installers will sometimes create a join which is less than optimal. It is difficult to teach a trainee this skill and difficult for an inexperienced or “DIY” installer to get a good chance of a good result. Positioning the sheets of grass by sight, along the cut line, relies on the assumption that the cut has been made perfectly straight and exactly parallel with the stitch lines, at a set distance from the stitch lines. However, even for factory produced cuts this assumption may not be entirely correct. A cut is acceptable as long as it is parallel with the stitch lines in the sense that it does not cut across stitch lines. Even if the cut is not perfectly straight a very good join can be made as long as the sheets are spaced the correct distance apart, to maintain the gauge of stitch lines across the join. However, the problem is that if the cut is not straight, or is not a precise distance from the stitch lines, then even an installer who is able to very precisely space the cut edges of the sheet may not succeed in the real object which is to maintain a precise distance between stitch lines on either side of the join.

It is an object of the invention to provide a measuring and positioning tool which allows for reliable positioning of sheets of artificial grass along a join line.

STATEMENT OF INVENTION

According to the present invention there is provided a positioning tool for positioning a sheet of artificial grass along a join line, the positioning tool comprising: a baseplate for placing against a surface of a sheet of artificial grass; a backplate joined to the baseplate and at right-angles to the baseplate, for placing against a corresponding backplate of a similar tool, the positioning tool including means for positioning a stitch line running along the edge of the sheet of artificial grass at a fixed distance from the backplate. When positioning two sheets of artificial grass for a join, at least two similar tools are used. Each tool is placed against a surface of one of the sheets of grass, so there is one tool in place on each of the sheets of grass. The grass is positioned in relation to the tool so that the stitch line running along the edge of the sheet of grass is a fixed distance from the backplate. When the two tools are brought together so that the backplates abut each other, the stitch lines along the edges of the two sheets of grass will be a fixed distance apart. This distance is set to correspond to the gauge of the stitch lines within a single sheet of grass, so that the gauge of the stitch lines is maintained across the join. In this way, grass can be prepared accurately for joining, ensuring an invisible join without ridges, gaps, or inconsistent strand density.

Preferably, there are provided gripping means for immovably gripping the surface of the sheet of artificial grass to the baseplate. The gripping means may including spikes for at least partially piercing the sheet of artificial grass. The gripping means may include a clamp for clamping the sheet of artificial grass against the baseplate.

In use, the sheet of grass may be positioned against the baseplate so that the stitch line running along the edge of the sheet is at a fixed distance from the backplate - i.e. parallel with the backplate at a predetermined distance from the backplate. Then, the sheet may be fixed to the baseplate, for example by clamping against the baseplate, so that the sheet remains in the correct position in relation to the backplate. Once this is done, the sheet of grass with the tool fixed on may be moved, to position the backplate of the tool against a backplate of a similar tool, and hence correctly position two sheets of grass in relation to each other.

The means for positioning the edge of the sheet of grass at a fixed distance from the backplate may be provided in a variety of forms. In one simple embodiment, the stitch line running along the edge of the sheet of grass may be positioned directly to correspond to a reference on the baseplate. However, it has been found preferable to position the stitch line running along the edge of the sheet of grass by means of a reference set in from the edge. Most artificial grass has visible parallelstitch lines running along the bottom of the backing sheet. The stitch line may also be visible from the top of the sheet of grass, with care. By lining up, for example, the third stitch line from the edge with a reference on the baseplate of the tool, the edge can be reliably positioned, even if the cut along the edge is not entirely straight.

Note that, as long as the cut along the edge of the sheet of grass does not cut across a stitch line, a cut which is not entirely straight can be tolerated. Any slight overlap along small parts of the join line caused by this can be corrected by trimming after the grass sheets have been folded over the glued tape. However, a rough cut can make it difficult to estimate the correct distance between sheets by eye in present practice. By using a stitch line set back from the edge, and positioning that in line with a reference on the baseplate, this problem may be overcome.

The reference on the baseplate is preferably a slot. In a preferred embodiment, a top surface of the baseplate is placed against a bottom surface of the sheet of grass, in other words the baseplate is placed underneath the sheet of grass. A particular stitch line, for example the third stitch line from the edge, can be easily positioned in line with the slot by looking through the slot from underneath the tool, and moving the tool until the third stitch line is in place and visible through the slot. The baseplate is then fixed in place in relation to the grass sheet, for example by clamping.

Where the edge is positioned in this way, by reference to a stitch line set back from the edge of the grass, the interface between the baseplate and the backplate is preferably a curved internal corner. This is preferable because the edge of the grass sheet can easily be moved in relation to the reference on the baseplate, and any minor imperfection in the cut along the edge of the sheet will not impede positioning.

A typical gauge of stitch lines in artificial turf is 3/8inch, about 9.5mm. By positioning with reference to the third stitch line from the edge, plenty of space is provided for a gradually curved internal corner, which assists with positioning.

With a curved internal corner, the sheet of grass when in the correct position can in some embodiments ride up the front surface of the backplate slightly. This allows the fixed distance between the cut edges of the sheets of grass, when positioned ready for joining, to be smaller than twice the thickness of the backplate. For some types of grass which need a very small gap on the join line, this is important to allow the backplate to be made thick enough that it is robust and resistant to damage.

The tool may include a handle to allow for easy movement of the tool, and hence positioning of the grass sheet, when the tool is fixed in place in relation to the grass sheet, for example by clamping the grass sheet to the baseplate. The handle may incorporate operating means for the clamping mechanism.

For example, the clamping mechanism may be spring biased into a clamped position, with an operating lever incorporated into the handle that can be squeezed against the spring to release the tool from gripping the grass sheet. The clamping mechanism may comprise a clamping plate which is parallel with the baseplate, and movable from a position spaced from the baseplate to a position close to the baseplate. The clamping plate is preferably spring biased towards the baseplate for clamping the grass sheet. The clamping plate and/or the baseplate may have spikes on a surface facing the other plate to assist with gripping the grass sheet.

The backplate may include means for temporarily joining the backplate to a backplate of a similar tool. For example, the joining means may be magnets.

In some embodiments, the predetermined distance from the stitch line running along the edge of the grass sheet to the backplate is adjustable. This is because different artificial grass products may need to be spaced apart by different predetermined distances (to correspond to the gauge of the stitching) in order to make a good join. In some embodiments, an interchangeable baseplate and/or an backplate may be provided to achieve this - the thickness of the backplate and the position of the slot or other reference on the baseplate define the set distance. However, multiple references (e.g. multiple slots or marks) could be provided on one baseplate, and spacers could be provided for adjusting the effective thickness of the backplate (which does not have to be a uniform thickness, as long as there is an easily preset distance when two backplates are placed against each other).

According to a second aspect of the invention, there is provided a method of joining two sheets of artificial grass, wherein each sheet of grass has parallel stitch lines, and a cut edge substantially parallel to the stitch lines, and the method using multiple similar tools which each comprises a backplate and a baseplate, the backplate joined to the baseplate substantially at right angles, and the method comprising the steps of: placing the baseplate of one of the tools against a surface of one of the sheets of grass, and positioning the sheet of grass in relation to the tool so that the stitch line running along the cut edge of the sheet of grass is at a predetermined distance from a surface of the backplate, and fixing the sheet of grass in position on the baseplate; placing the baseplate of another of the tools against a surface of the other sheet of grass, and positioning the sheet of grass in relation to the tool so that the stitch line running along the cut edge of the sheet of grass is at a predetermined distance from a surface of the backplate, and fixing the sheet of grass in position on the baseplate; placing the backplates of the tools together to position the two sheets of grass in relation to each other with their respective stitch lines running along cut edges set at a fixed distance apart; and removing the tools from the sheets of grass and fixing the two sheets of grass together in position.

Further preferable details of the method will be apparent from discussion of the features of the tool. In particular, the cut edge is substantially parallel to the stitch lines, in that it does not cut any stitch line. However, the cut edge does not have to be, and is not likely to be, perfectly straight. Preferably the grass sheets are positioned on the tools by reference to a stitch line spaced from the cut edge, for example, the third stitch line from the edge.

Multiple tools may be fixed to each grass sheet. For example, tools could be placed along the cut edge, and fixed in position, at intervals of about 1-2 metres along the entire length of the join. By fixing the tools in place in relation to their respective sheets of grass, and then moving the tools and hence the sheets of grass so that the backplates abut each other, the two sheets of grass - which could be large and heavy - are reliably placed in position ready for joining. Preferably, the tools whose backplates abut each other can be temporarily fixed together, for example by magnets.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made by way of example only to the accompanying drawings, in which:

Figure 1 is a perspective view of a tool according to the first aspect of the invention;

Figure 2 is a perspective view of the tool of Figure 1 , showing a baseplate and backplate assembly detached from a handle;

Figure 3 is a perspective view of two identical tools, each tool like the tool of Figure 1 ; and

Figure 4 is a perspective view of the two tools of Figure 3, with the backplates of the tools abutting each other.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring firstly to Figure 1 , a measuring and positioning tool for use in installation of artificial grass is indicated generally at 10.

The tool comprises a backplate 12 and a baseplate 11. The backplate 12 and baseplate 11 are each made of sheet metal, of substantially uniform thickness.

The backplate and baseplate are disposed at right angles to each other.

In this embodiment, the backplate and baseplate are formed from a single sheet, bent into an “L” shape.

The internal corner 14 between the backplate 12 and baseplate 11 is curved, rather than a sharp right-angle corner. In this embodiment, a sheet of artificial grass is placed with the underside of the sheet against the upper surface of the baseplate 11 . As such, the cut edge of the sheet of grass will sit in the internal corner 14 between the backplate 12 and the baseplate 11. The curvature of the corner prevents any roughness of the cut edge from butting up to a sharp corner, and hence a cut which is not perfectly straight can be tolerated, as long as the cut is parallel with the stitch lines of the grass sheet to the extent that the cut does not cut across any stitch lines.

A slot 16 is provided along nearly the whole width of the baseplate 11 . The slot 16 is provided in the baseplate 11 parallel with the plane of the backplate 12. The slot 16 is a fixed distance from the backplate 12, all the way along the length of the slot. The slot is as long as it can be without compromising the robustness of the baseplate 11.

In use, one sheet of artificial grass is placed on top of the upper surface of the baseplate 11. Typically, the artificial grass has stitch lines which are easily visible on the underside of the grass sheet. The sheet of artificial grass is positioned on the baseplate 11 so that the third stitch line in from the cut edge of the grass sheet is visible through the slot.

Clamping plate 18 is movable from a position spaced from the baseplate 11 (see Figure 1) to a position close to or against baseplate 11 (see Figure 3, left hand side). The clamping plate is substantially parallel with the baseplate 11. The clamping plate has a plurality of spikes on the side of the clamping plate 18 facing the baseplate 11 . The spikes assist with gripping a sheet of artificial grass.

To grip a sheet of artificial grass in position against the baseplate 11 , the clamping plate 18 is moved to the position close to the baseplate 11 (or as far as it will go, when there is a sheet of grass in place). This clamps the sheet of grass between the clamping plate 18 and the baseplate 11.

A U-shaped handle 20 is provided. The handle 20 is useful for manoeuvring the tool 10, including when a sheet of grass is clamped in place. Additionally, the handle incorporates a trigger 22 for controlling movement of the clamping plate 18.

The clamping plate 18 is fixed to a pair of sliding shafts 24. The sliding shafts 24 slide within opposing arms of the U-shaped handle 20 to allow movement of the clamping plate 18 while it remains parallel with the baseplate 11. Springs (not visible in the drawings) are disposed inside the handle 20 for biasing the clamping plate 18 in the position close to the baseplate 18 (i.e. in the clamped position).

To release the clamp and allow the sheet of grass to be positioned in the tool, repositioned, or removed from the tool, the trigger 22 is squeezed. This moves the clamping plate 18 away from the baseplate 11 , against the action of the spring. When the trigger is released the clamping action is engaged.

Figure 2 shows how the baseplate 11 and backplate 12, which in this embodiment are formed as one piece, can be detached from the handle 20. The backplate 12 is simply screwed onto the handle by four screws 26. The backplate 12 can easily be removed and replaced with a different backplate. In this way, different backplates can be provided for use with different types of artificial grass. Typically, the gauge of the stitch lines (i.e. the distance between the lines of stitching) will define how far apart two sheets of grass need to be to make a good join. Different grass sheets have different gauges and as such, multiple backplates can be provided for use with different grasses. The combined baseplate 11 and backplate 12 is a simple part and as such multiple sizes can be provided at low cost. The clamping mechanism including the plate 18, shafts 24, springs, and trigger 22 are all incorporated into the handle, so that only one handle with clamping mechanism needs to be provided to fit many different sizes of backplate.

Also visible in Figure 2 are a pair of magnets 28. The magnets are preferably capable of around a 10N pull when abutting similar magnets on a similar tool. The magnets assist with positioning two tools together, and holding them in position.

One of the magnets 28 is positioned with its north pole facing outwards from the back of the backplate 12, the other with the south pole facing outwards. Hence when two similar tools are abutting each other back to back, opposite poles will be in corresponding positions and will attract.

Figure 3 shows a kit comprising two tools 10. Each of the tools 10 in Figure 3 is identical. In Figure 3 the tools are being brought together, noting that magnets 28 are in corresponding positions, with opposite poles facing each other. In Figure 4 the backplates 12 of the two tools abut each other and the magnets are holding the tools in place in relation to each other.

The tools are used with positioning two sheets of artificial grass in relation to each other, ready for joining. At least two tools are used, one for each sheet of grass, but preferably multiple tools are positioned along the cut edge of each sheet of grass, for example at intervals of about 1 m. The edge may be many metres long, and the cut edge of one sheet of grass needs to be lined up at a set distance from the cut edge of the other sheet of grass, all the way along the proposed join. By using multiple tools on each sheet, handling the sheet of grass and moving it into the correct position becomes considerably easier.

The use of the tools allows for the cut edges of two sheets to be precisely lined up, so that the stitch lines of the two sheets of grass run exactly parallel, with the gauge of the stitch lines being maintained consistently across the join. Even if the cut line is rough, as long as it does not cut across a stitch line a very good join can be achieved. Once the sheets of grass are in position, they can be temporarily fixed with nails, folded over, glued onto a joining tape and finished according to known practice.

Figure 5 shows an alternative embodiment of a tool 10’. The alternative embodiment 10’ differs from embodiment (10, Figures 1-4) only in the form of the slot in the baseplate. The alternative embodiment 10’ has a slot 16a extending along a large part of the width of the baseplate, and in addition notches 16b which are in line with the slot 16a, and are cut into the sides of the baseplate. The notches in the sides of the baseplate allow for an “effective slot length” which is the full width of the tool, in that the stitch line on the base of the sheet of grass can be positioned in line with a reference at maximally spaced positions along the stitch line. This assists with precise alignment of the stitch line to the reference, making sure the tool is exactly parallel with the stich line. The embodiments described above are provided by way of example only, and various changes and modifications will be apparent to persons skilled in the art without departing from the scope of the present invention as defined by the appended claims.