This invention relates to apparatus for laying beads of adhesive on a surface to have a covering adhered thereto. In particular, but not exclusively, this invention relates to apparatus for laying beads of tiling adhesive as a step in the process of tiling the surface. Though this invention could be used for applying adhesive beads to a surface other than for securing ceramic or similar tiles thereto, it will hereinafter be described exclusively with reference to that application, though it is to be understood the invention is not limited thereto.

Tiling is undertaken by covering a part of a surface to be tiled with tiling adhesive, whereafter the tiles are pressed into engagement with the adhesive and then left while the adhesive sets, an adjacent area then being similarly treated until the whole surface is tiled. In order to allow the laying of the tiles in a substantially co-planar disposition, the usual practice is for the adhesive to be trowelled on to the next part of the surface to be tiled and then spread out to give a rough coating . The applied adhesive is scraped with a toothed spreader, such that parallel beads of adhesive remain on the surface. The object is to have beads of a uniform thickness and profile, but any minor variations in the beads as well as in the tiles themselves can be accommodated by applying pressure to the tiles so as to spread the beads sideways until the exposed surfaces of the tiles are substantially co-planar.

The laying of the beads of adhesive is both time consuming and a skilled job, since the success of the tiling job depends to a large extent upon the quality of the laying of the beads. In an attempt to enhance the quality and also to reduce the time taken to produce the beads, there have been proposals for machines for laying adhesive beads on the surface to be tiled. Once such proposal is to be found in my own earlier International Patent Publication No. WO 2006/120480. The machine described in that specification has a relatively large reservoir of tiling adhesive connected to a dispensing head having a plurality of outlet nozzles and a ram arrangement for pressurising the adhesive in the reservoir. When pressurised, the machine is wheeled across a surface to be tiled, so depositing on that surface a plurality of parallel beads of adhesive.

Practical trials of the machine of WO 2006/120480 have shown that it is very difficult to achieve beads of a constant profile. This invention stems from further development of that machine, in an attempt both to increase the speed of laying beads of adhesive while achieving a better consistency in the profile, and in particular the height, of the beads laid on the surface.

According to this invention, there is provided apparatus for laying beads of adhesive on a surface to be covered, comprising a wheeled chassis supporting a holder for a reservoir of adhesive, an adhesive dispensing head having a plurality of outlet nozzles for adhesive supplied thereto and supported by the chassis to extend adjacent said surface to be covered, a duct connecting a held reservoir of adhesive to the dispensing head, means to drive adhesive from a held reservoir along the duct to the dispensing head, a power drive arrangement for the wheeled chassis to effect movement of the chassis along said surface, and control means for the power drive arrangement whereby the chassis moves at a substantially constant speed so that each bead of adhesive is of a substantially uniform cross-sectional profile.

In a particularly preferred form of the apparatus, there is provided a ram for driving a piston associated with reservoir, and a drive mechanism for the ram, whereby the ram pressurises the adhesive in the reservoir thereby to drive adhesive therefrom, along the duct to the dispensing head and then out of the outlet nozzles of the head. That drive mechanism advantageously is operated by the control means such that the dispensing of the adhesive is in a controlled manner, as is the driving of the wheeled frame by the power drive arrangement. In the following description, reference will exclusively be made to the tiling of a surface, though the invention is not limited thereto.

It will be appreciated that the machine of this invention differs from that described in WO 2006/120480, in that the movement of the wheeled chassis along the surface to be tiled is precisely controlled and, preferably, so too is the dispensing of the adhesive. By controlling these two factors, it has been found possible to achieve the laying of uniform beads of adhesive over a relatively large area in a relatively short time, as compared to the traditional hand-laying of beads as described hereinbefore or as compared to using the machine described in WO 2006/120480. Preferably, the power drive arrangement comprises an electric motor drivingly coupled to at least one pair of wheels supporting the chassis on the surface to be tiled . In this case, the motor should be controlled to effect driving of said pair of wheels at a substantially constant rate, when energised. Thoug h th at rate may be adj usta bl e to be a suitable value for the characteristics of the adhesive and the required bead profile, it should be held substantially constant for the duration of the laying of beads of adhesive over a given area to be tiled.

The wheeled chassis may include a second pair of wheels bearing on the surface to the tiled, the pair of wheels nearer the dispensing head being provided with suspension in order to allow the nozzles of that head closely to follow the surface to be tiled, notwithstanding minor variations or imperfections in the smoothness of that surface. In addition, the height of the dispensing head above the surface to be tiled may be adjustable, either by adjusting relative to the chassis the position of the wheels nearer the head or adjusting the position of the dispensing head relative to the chassis. Moreover, the dispensing head may be releasable from the chassis for replacement by another, such that different bead configurations may be obtained, such as the profile of those beads or the number of beads per metre laterally of the direction of movement of the wheeled chassis. In the preferred form of the apparatus of th is invention , a further electrically-powered drive arrangement is provided for the ram, that drive arrangement also being operated by the control means. In one embodiment, the ram includes a piston , a threaded rod connected to the piston, a nut threaded on the rod and an electric motor drivingly coupled to the nut and operated by the control means. In th is case, the electric motor should be - A -

controlled either to run at a constant speed or to maintain a constant pressure in the adhesive entering the duct.

An alternative drive means for the adhesive may comprise a pneumatic or hydraulic ram for driving a piston associated with the reservoir and a motor- driven pump for supplying fluid under pressure to the ram, thereby to drive adhesive out of the reservoir, along the duct to the dispensing head and then out of the outlet nozzles of the dispensing head . The motor driving the hydraulic or pneumatic pump should be operated by the control means and there may be provided at least one of an adhesive pressure sensor and a motor load sensor connected to the control means, which is arranged to reduce or inhibit drive current to the motor in the event that the output from at least one of the sensors exceeds a predetermined threshold.

It is preferred for there to be a valve in or immediately adjacent the dispensing head, to cut off the supply of adhesive to the dispensing head other than when beads of adhesive are to be laid. Preferably, the valve is electrically operated and is controlled by the control means, such that when motion of the wheeled chassis is stopped, the valve is immediately closed so as to prevent the depositing of a mass of adhesive at the end of a run. In this case, immediately following the closing of the valve (concurrently with the stopping of the electric motor), the motor pressurising the adhesive is briefly reversed, so as to reduce the pressure in the adhesive.

In addition to, or instead of, the electrically operated valve, there may be a manual valve whereby an operator may deliberately inhibit the supply of adhesive to the dispensing head. In the alternative, there may be a manually operable trigger at the dispensing head, which trigger is connected back to the control means such that use of the trigger causes the electrically operated valve to be moved as required, either to allow the flow of adhesive or to inhibit that flow.

The duct connecting a held reservoir of adhesive to the dispensing head may be flexible such that the dispensing head may be removed from the apparatus and used manually, for example for applying beads of adhesive to a wall surface rather than to a floor. For such a case, the dispensing head may include a manually grippable handle arrangement including a trigger controlling both the means to drive adhesive from the reservoir and also the valve adjacent the dispensing head. The nozzles in the dispensing head may be of different sizes, with the nozzles furthest from the duct connected to the head having a greater area than the nozzles nearest the duct. Having regard to the considerable viscosity of tiling adhesive, and so the consequent pressure drop across the width of the dispensing head from the connection thereto of the duct, this allows uniform beads to be laid on the surface to be tiled . An alternative solution to the problem of the viscosity of the tiling adhesive is to provide the dispensing head with a plenum chamber, the duct being connected to the plenum chamber and there being a plurality of outlets from the plenum chamber for feeding a dispensing chamber, with the outlet nozzles leading out of the dispensing chamber.

Some tiling adhesives must be mixed immediately before use and when mixed, an exothermic reaction takes place within the adhesive. In order to prolong the useful life of such a mixture, and also to ensure the dispensing of uniform beads of adhesive, the reservoir for the adhesive may be provided with a cooling coil, connected to a source of fluid cooled below room temperature. Such an arrangement may ensure relatively uniform viscosity for the tiling adhesive such that it is possible to lay beads of adhesive having more or less a constant profile.

By way of example only, a specific embodiment of a tiling adhesive bead laying machine of this invention and certain modifications thereof will now be described in detail, reference being made to the accompanying drawings, in which:-

Figure 1 is a general perspective view of the machine, having an adhesive holder arranged with its axis vertical; Figure 2 shows the attachment of the dispensing head to the wheeled chassis of the machine; Figure 3 is a diagrammatic cross-sectional view through the adhesive holder and a held cartridge of adhesive, for the machine of Figure 1 ;

Figure 4 shows a formation at the open end of the reservoir, for locating a cartridge in its holder; Figure 5 is a perspective view of an adhesive laying machine similar to that of Figure 1 but having the adhesive holder arranged with its axis horizontal;

Figure 6 is a diagrammatic cross-sectional view through the adhesive holder and a held cartridge of adhesive, for the machine of Figure 4; Figures 7 and 8 are isometric and plan views on a first dispensing head similar to that of the machines of Figures 1 or 4;

Figure 9 is an isometric view on an alternative dispensing head;

Figure 10 illustrates use of the machine for the manual laying of beads of adhesive; and Figure 1 1 shows a cooling coil for use with the machines of Figures 1 and 4.

Referring initially to Figure 1 , there is shown a tiling adhesive bead laying machine of this invention. This machine comprises a chassis 15 provided with two pairs of ground wheels, wheels 16 being at the front of the chassis (having regard to the normal direction of movement of the chassis shown by arrow A) and being power driven, and wheels 17 being at the rear.

The chassis is in the form of a platform which supports an electric motor 18 which drives the front wheels 16 through a drive train (not shown) contained within housing 19 also mounted on the chassis. The wheels 16 may be on a common driven axle, or the two wheels may be separately driven by individual drive trains, coupled to the two ends of the electric motor 18. The rear wheels

17 are provided with sprung suspension arrangements (not shown) disposed within housings 20 mounted on the chassis, so that the rear wheels may move vertically to accommodate minor variations or imperfections in the smoothness of the surface over which the machine is to run. A cylindrical container 22 for a cartridge of tiling adhesive is mounted on the chassis with its axis vertical, between the front and rear pairs of wheels. The container has a removable lid 23 having a central cover 24 for a connector 25 (Figure 3) to the cartridge of tiling adhesive, the connector being provided on one end of a flexible hose 26 for the tiling adhesive. Mounted at the rear of the chassis is a transverse dispensing head 27 for laying beads 33 of tiling adhesive on the surface on which the chassis runs. The other end of the flexible hose 26 connects into an electrically operated valve 28, the outlet pipe 29 from which connects into a distribution bar 30 having three connections into the dispensing head 27. That head has a plurality of spaced outlet nozzles - not shown, but discussed in more detail with reference to Figures 7 and 8. A support clip 32 for the other end of the flexible hose is arranged on the chassis, between the container 22 and the valve 28.

A control box 34, containing an electronic control circuit, is mounted on the chassis adjacent the electric motor 1 8 and on the opposed side of the chassis there is provided a rechargeable battery (not shown), connected to the control box and also to the electric motor. A generally U-shaped handle 35 is secured to the chassis and, at its upper end, has a control panel including switches 37 and speed control knobs 38. Figure 2 shows in more detail the mounting of the dispensing head 27 to the chassis 1 5. The d ispensing head includes a spring bracket 40 which extends for the width of the chassis across the head, to allow the head to be secured to the chassis by means of a plurality of threaded studs 41 and wing nuts 42. At each end of the dispensing head 27, there is provided a plate 43 carrying a wheel 44 mounted for vertical movement in a slot 45, there being a spring (not shown) urging the wheel downwardly to engage the surface to be tiled and arranged so as to keep the adjacent end region of the dispensing head at the required distance from the surface.

Figure 3 is a cross-section through the container 22 of the machine of Figure 1 . As can be seen, a cartridge 47 is disposed within the container, the lower open end 48 of the cartridge resting on a ledge 49 formed within the container. The container has an end wall 50 with a central neck 51 out of which adhesive (not shown) held within the cartridge is dispensed, by upward movement of a piston 52, towards the end wall 50. Annular barb-shaped ribs 53 and 54 are formed within the cartridge, rib 53 serving to prevent removal of the piston out of the lower open end 48 of the cartridge and rib 54 serving to hold the piston adjacent the end wall 50, when the piston has been moved to that end wall on dispensing substantially all of the adhesive within the cartridge. A mechanism 55 is disposed in the lower region of the container 22, for forcing the piston upwardly towards the end wall 50, that mechanism including an electric motor 56 drivingly connected to a telescopic screw- threaded ram assembly 57 furnished with a pressure plate 58 at the upper free end thereof, for bearing on the piston 52. The motor 56 is connected to the control box 34, for operation thereby.

Also shown in Figure 3 is the removable lid 23, screw-threaded to threads formed externally on the upper end of the container 22. The lid has a central opening 59 through which extends the connector 25, for coupling the flexible hose 26 to the neck 51 of the cartridge 47 located within the container. The cartridge 47 is restrained against rotation with respect to the container 22 by way of a projection 60 (Figure 4) extending into a notch 61 formed in the cartridge wall at the lower open end 48 thereof. Figure 3 further shows a port 62 in the piston 52, to allow the escape of air from within the cartridge as the piston is fitted thereto, following the filling of the cartridge with adhesive. Once the piston has been fitted into the cartridge, the port is closed by a plug 63.

Figures 5 and 6 show a modification of the machine of Figures 1 to 4, where the container for the adhesive cartridge is mounted on the chassis with its axis horizontal. Like parts with those of Figures 1 to 4 are given the same reference numerals in Figures 5 and 6 and will not be described again here. The container 65 is of a significantly lesser axial length than container 22 as no space need be provided for accommodating the ram assembly 57 of the machine described above. With the arrangement of Figure 5, the piston 52 of the cartridge 47 is driven by a ram assembly 67 mounted on the container lid 68, that ram assembly having a pressure plate 69 carried on the end of a threaded rod 70 supported in bearings 71 on the lid 68. A nut 72 is threaded onto the rod 70, the nut being provided with teeth around its periphery and engaged by a worm 73 driven by an electric motor 74. As with the previous arrangement, the motor 74 is connected to the control box 34, for operation thereby. A cover plate 75 is bolted to the lid 68 and extends over the ram assembly 67 but has a central opening for the threaded rod 70 to project therethrough.

In other respects, the arrangement of Figures 5 and 6 is essentially the same as that of Figures 1 to 4 and is used in the same manner; no further description will here be given of the arrangement of Figures 5 and 6.

Figures 7 and 8 show a dispensing head suitable for use with the adhesive dispensing machines described above, but with the plates 43 removed, for clarity. The dispensing head 76 has a main body 77 having a through-bore 78 closed at its opposed ends by threaded caps 79. A boss 80 is provided on the front (having regard to the normal direction of travel shown by arrow A on Figure 1 ) of the body 77, a hole being formed through that boss to communicate with the through-bore 78. A coupler 81 for the flexible hose 26 is mounted on the boss 80. The rear of the body has a plurality of outlet nozzles 82 arranged at a common pitch across the width of the dispensing head but the effective area of each nozzle varies across the width of the dispensing head. In the central region of the head, the nozzles have the smallest effective area and that effective area of the nozzles gradually increases towards the side edges of the head. In this way, beads of adhesive of substantially uniform cross-section will be dispensed by the head, having regard to the relatively viscose nature of tiling adhesive being fed centrally into the through-bore 78.

The dispensing head 27 shown in Figures 1 and 5 differs from head 76 in that the head 27 includes a distribution pipe 30 having a coupler for the flexible hose 26. That distribution pipe has three exit tubes to the through bore 78 of the dispensing head, so as to distribute adhesive across the width of that through bore. In turn, this reduces the requirement for having nozzles of increasing areas from the central region to the sides of the head, and may wholly eliminate the need for nozzles of different sizes.

Figure 9 shows an alternative arrangement for distributing adhesive into the through-bore 78, to ensure beads of a uniform size are extruded from the nozzles 82. Here, a separate plenum chamber 85 is provided with a coupler 86 for the flexible hose 26, that plenum chamber having three exit tubes 87 each communicating with a respective boss 88 on the body 89 of the dispensing head. Each of those bosses has a hole leading to the through-bore 90 of the dispensing head thereby reducing the effect of the viscosity of the tiling adhesive.

The machines of Figures 1 and 5 are used in the same way, once the containers thereof have been loaded with a cartridge of tiling adhesive. The speed control knobs 38 on the control panel are set to appropriate values to give the required translational speed of the chassis 15 by the motor 18 and the required adhesive dispensing rate by the motor 56 (or 74). Then, when the laying of beads of adhesive is to commence, one switch 37 is depressed so that the control box supplies current to the motors 18 and 56 (or 74), causing the chassis to move at a constant rate over the surface to be tiled and valve 28 to open, allowing the dispensing of a plurality of parallel beads 33 of adhesive out of the head 27, onto the surface over which the machine runs. Provided that the controls have been appropriately set, the beads 33 will all have substantially the same cross-sectional area, for as long as the chassis continues to move.

At the end of a pass, the switch 37 is released so that movement of the chassis ceases and the valve 28 is closed , stopping the dispensing of adhesive. The machine may immediately be turned round to perform another pass, by operating the switch 37 once more. If the machine is not immediately to perform another pass, then the other switch on the control panel 36 is operated, to cause a brief reversal of the motor 56 (or 74) of the ram assembly, thereby to remove pressure from the piston 52 of the cartridge and so relieve the adhesive of pressure. The tiling adhesive bead-laying machines of Figures 1 and 5 may be used to lay beads of tiling adhesive on a wall, without having the machine power-driven along a surface. The flexible hose 26 and valve 28 are removed from the support clip 32 and a handle assembly 92 (Figure 10) is mounted on the hose, adjacent the valve. That handle assembly includes a trigger switch 93 and a push button 94 both connected back to the control box 34, the trigger switch 93 serving to control operation of the valve 28 (via the control box) and the push button to effect reversal of the motor 56 associated with the ram assembly 57, or the motor 74 of the ram assembly 67 in the case of the embodiment of Figure 5. The wheel plates 43 may be removed from the dispensing head (as shown) or may be left in place, and the head is manually moved over the wall surface, to lay beads of adhesive thereon.

At the end of a pass of the head 27 across a surface to be tiled, the trigger switch 23 is released so inhibiting the exuding of beads of adhesive from the head and if another pass is not immediately to be performed, the push button 24 should be pressed so causing the motor 56 (or 74) to reverse briefly, thus relieving pressure on the adhesive in the cartridge.

Some tiling adhesives must be mixed shortly before use. Many of those adhesives undergo an exothermic reaction when mixed, which may produce considerable heat. This heat reduces both the useful life of the mixed adhesive and also reduces the viscosity thereof. In turn, the reduced viscosity is likely to give rise to beads of adhesive having smaller cross-sectional areas than with cold adhesive, from the same nozzles. In order to minimise the effect of this, the container 22 may be encircled by a helical coil 96 (Figure 1 1 ) through which is circulated chilled thermal transfer fluid, such as a refrigerant supplied from a cooling plant (not shown). In the case of a relatively large container, where very considerable heat may be generated, a flexible cooling coil (not shown) may also extend around the flexible hose 26. Advantageously, the cooling plant may also be mounted on the chassis 15.