WO2002008096A1

WO2002008096A1 - Machine and method for spraying material

Info

Publication number: WO2002008096A1
Application number: PCT/GB2001/003288
Authority: WO
Inventors: Terje Lindberg
Original assignee: Burrows, Anthony, Gregory
Priority date: 2000-07-22
Filing date: 2001-07-23
Publication date: 2002-01-31
Also published as: AU2001277610A1; GB0017957D0

Abstract

A machine (50) for spraying building material comprises a hopper unit (1) readily releasably connected to a wheeled base unit (19) by means of handled nuts (22) clamping horizontal, hook-like brackets fixed to the unit (1) against the base unit (19) and by means of a bayonet lock between a paddle within the hopper unit (1) and a shaft which is mounted on the base unit (19) and to which is fixed a feeder disc. A cover (15) is openable to allow access to the feeder disc and comprises an outer panel, an inner panel detachably mounted on the outer panel, and a rubber seal mounted on the inner panel and partly resting against the feeder disc and partly pressed hard against a stationary metal plate and a stationary rubber plate.

Description

MACHINE AND METHOD FOR SPRAYING MATERIAL

This invention relates to spraying of material, especially building material.

In many countries, it is becoming more and more difficult to find people who are able and willing to carry out the heavy and often unpleasant work which is traditionally required by many of the practices in the building and construction industries. These industries are thus facing a steadily worsening problem to which solutions must be found. A conventional method of applying mortar or concrete is known as the wet spray method in which a pre-mixed wet batch of mortar or concrete is loaded into the spraying machine which sprays the batch onto the relevant surface. Often, it is desirable to have documentation as to the composition of the wet mortar or concrete being sprayed. This is, in effect, done by the batching, since the machine is loaded with a batch, the components of which have been measured.

Another conventional method of applying mortar or concrete, particularly in the concrete repair industry, is known as the dry spray method. One generic type of machine in common use for this method has a hopper from which dry, pre-mixed mortar or concrete flows, via a rotating paddle which keeps the material fluid, into a rotating feeder drum or disc. From here, the dry material is blown by compressed air via a rubber transfer plate through a hose to a mouthpiece. In the mouthpiece, and just prior to ejection from its nozzle, the dry material is mixed with water. The now wet mortar or concrete is thus then sprayed onto the substrate at which the nozzle is aimed. The composition of the wet mortar or concrete depends on the settings of the machine, which in turn depends on the "feel" of the operator. The window for acceptable material composition is quite narrow, because the material cannot vary much in practice since it would otherwise fall off the surface to be sprayed, or run, or be too dry.

US-A-5094403 describes a concrete spraying gun having a rotatable multi-chamber drum, with a top feed hopper for receiving a dry concrete mixture in a chamber, and a bottom outlet pipe for discharging the dry concrete mixture from the chamber, the outlet pipe having a compressed air connector for connection to a compressed air source. The upper surface of the drum adjoins a gasket having one or more openings fixed to a clamping plate. The lower surface of the drum adjoins a gasket which is fixed to a base plate. The hopper and the outlet pipe are spaced such that a chamber which communicates directly with the hopper can be moved so that it no longer communicates with the hopper but communicates with the outlet pipe. The clamping plate has a compressed air connector for blowing the dry mixture out into the outlet pipe. An opening is present for allowing compressed air to escape from the chambers, which opening is located between the position when the chamber communicates with the outlet pipe and the position when it communicates with the hopper outlet. A connection is provided in the upper gasket which connects to at least one chamber empty of concrete and one chamber containing concrete to equalise the pressure between the chambers.

US-A-4376600 describes apparatus for feeding course- grained, lumpy dry materials from a hopper to an outlet chamber into which materials are blown. It has two drums that rotate in unison about a common vertical axis and have circumferentially arranged material chambers that are coaxial with one another. A plate between the two drums has a passage with which the chambers of the drums can be brought into register by rotation. The upper drum has a plurality of air chambers which receive compressed air conducted through the passage from each of the chambers of the lower drum. A connecting channel serves to increase the pressure on the outer side of the chambers of the lower drum. Multiple openings into the atmosphere discharge the chambers of the upper drum. With this arrangement the pressure drop is reduced and the distance between a pressurised drum chamber and an unpressurised one is substantially increased, thereby reducing dust production and wear.

US-A-4462719 describes a concrete gun comprising in combination a drum, a plurality of chambers arranged in the drum in a circular array and extending parallelly to the axis of the drum, sealing plates of elastomeric material engaging the ends of the drum and closing the chambers, a vent orifice comprising a recess in one of the sealing plates, the recess being located to be successively in register with the chambers upon rotation of the drum, an air filter communicating the recess with the surrounding air and a clearing device for the recess including an actuating element extending from the recess to outside the gun. By reason of the external actuating element the vent orifice can be periodically cleaned of deposited residue without danger or having to shut down the machine.

US-A-4440499 describes a method and an apparatus for blowing mortar or concrete on the feeding of compressed air, in which dry-mixed materials are quantitatively jetted from a nozzle at a blowing machine, and liquid is supplied in a determined amount depending on the compressed air current through the nozzle, so that grains of the material are mixed with the liquid while the materials are being fed, and the property of such materials is changed from a dry condition to a wet condition of a pre-determined water-cement ratio, and the wet material is jetted from a nozzle at the end of a hose. In a further known example of a concrete spray machine, a feeder disc is provided which is a thick, metal, horizontal, wheel-like disc which contains a number of cavities recessed into its upper surface and separated by spoke-like divisions. A rubber transfer plate presses against the upper face of the feeder disc and has one aperture to admit air to the feeder disc and another through which the dry mortar or concrete material is blown into the hose leading to the nozzle. The rubber transfer plate is pressed hard against the upper surface of the disc by a hydraulic screw arrangement. The cavities serve as temporary receptacles for the dry mortar or concrete from the hopper. The material in each cavity is transferred to the hose leading to the nozzle by being blown out of each cavity in turn as it passes under the apertures in the rubber transfer plate. Since the rubber transfer plate has to be replaced at intervals, access is provided to allow its replacement. This access is provided through a hatch having a cover which is traditionally fastened by a screw arrangement which is relatively difficult to unfasten, often requiring the use of tools. The hatch opening is provided with a rubber seal which lies in part against the circumference of the feeder disc and which in part is pressed hard against the slightly protruding outer curved edge of the rubber transfer plate. This rubber seal, which is attached to the hatch cover, also wears quite quickly and has to be frequently replaced owing to its being subjected to a sandblasting effect caused by impinging particles in the air stream. Replacement of the rubber seal also involves replacement of the hatch cover to which the seal is attached.

Such conventional concrete spray machines are quite heavy and cumbersome, weighing upwards of 250kg. They also have parts which are subjected to heavy wear and which thus have to be serviced or replaced at frequent intervals. Among the main wearing parts are the rubber transfer plates. Others of the main wearing parts are the feeder drums or discs themselves. In the case where there is a rubber seal which lies in part against the circumference of the feeder disc and in part against the outer curved edge of the rubber transfer plate, this rubber seal also has to be frequently replaced. Concrete spray machines are in popular use, and are often transported from one building site to another. Conventional machines are not easily taken apart after a period of use owing to seizure of the relevant parts, and are therefore usually transported as they stand. This entails the use of a comparatively large van or lorry owing to the height of the machine, and in lifting of the relatively heavy machine.

Several spray machines of the type with feeder discs are commercially available. All of them suffer from various problems. Firstly, access to the feeder disc for inspection, servicing or replacement is cumbersome. Secondly, opening of the access hatch for replacing the rubber transfer plate is cumbersome and often requires the use of tools. Thirdly, replacing of the rubber access hatch seal is cumbersome. Fourthly, dismantling of the machine for transport between sites is difficult and normally avoided. This results in the use of vehicles which are volumetrically larger than would otherwise be necessary. Fifthly, except for the control of the water supply, the controls of the machine are on the machine itself, or are on a console near to the operator. This means that the operator has no control over the nozzle output at the nozzle and must rely on pre-setting of the controls, or must communicate in some manner with another operator at the machine or control console. These arrangements are inefficient, and result in wasted time and material during the reiteration of the adjustments of air, water and material feed needed to produce the required consistency and constancy of the output. The material wasted in adjusting the output needs to be collected, removed from the site, and deposited with the time and expense that this entails. Sixthly, they are heavy and difficult to lift, requiring a crane or several men. They require a relatively heavy vehicle capable of transporting upwards of 250kg. Seventhly, because of the forms of their mechanical drives, they are inefficient in terms of energy consumption, requiring the use of 3-phase power supplies. The provision of a 3-phase supply is very often cumbersome, but sometimes downright difficult or even impossible (in which case generators are needed) .

According to a first aspect of the present invention, there is provided a machine for spraying material, including an interior part to which access is required, and a cover openable to allow access to said interior part, said cover comprising an outer panel and an inner seal detachably connected to said outer panel.

Owing to this aspect of the present invention, it is possible to arrange that the seal is easily replaced when so required.

According to a second aspect of the present invention, there is provided a machine for spraying material, including an interior part to which access is required, and a cover readily openable to allow access to said interior part.

Owing to this aspect of the invention, the cover is readily openable to allow access to the interior part, to permit inspection, maintenance or replacement of the same. According to a third aspect of the present invention, there is provided a machine for spraying material, comprising a hopper unit, a base unit, and a readily releasable arrangement connecting said hopper unit detachably to said base unit.

According to a fourth aspect of the present invention, there is provided apparatus comprising:- a machine for spraying material, comprising a hopper unit, a wheeled base unit, and a releasable arrangement connecting said hopper unit detachably to said base unit, and a ramp device for use in wheeling said base unit, in a condition detached from said hopper unit, onto a vehicle.

According to a fifth aspect of the present invention, there is provided a method comprising providing a machine for spraying material, detaching a hopper unit of machine from a base unit of said machine, transporting said hopper unit and said base unit in a condition detached from each other, and reattaching said hopper unit to said base unit.

Owing to these aspects of the present invention, it is possible to provide a material spraying machine whereof a hopper unit and a base unit are easily put together or subsequently dismantled, allowing easier maintenance of the machine as well as reducing the vertical height of the machine for ease of transportation. According to a sixth aspect of the present invention, there is provided a machine for spraying building material, including an outflow duct and an actuating arrangement for controlling a plurality of functions of said machine, said actuating arrangement being located exteriorly of said duct in an outlet region of said duct.

Owing to this aspect of the invention, an operator can control a plurality of functions of the machine from his working location, as opposed to the location of the machine. The functions controllable from the working location may be any two of supply of dry material to a nozzle at the working location, supply of air for transporting the dry material to the nozzle, and supply of liquid, particularly water, to mix with the dry material.

According to a seventh aspect of the present invention, there is provided a machine for spraying material, including a handle for use in manually pulling said machine over the ground or floor, said handle having an outer end for grasping by the puller and an inner end mounted for turning about a substantially horizontal axis, and an abutment disposed above said handle at a location outwardly of said inner end and limiting upward turning of said handle in order to allow the puller to lift the inner end of the handle relative to the ground or floor.

Owing to this aspect of the invention, it is possible for the puller to lift the nearer part of the machine in order to be able to lift it over obstacles at the ground or floor. According to an eighth aspect of the present invention, there is provided a machine for spraying material, having any one or more of the following features :- a material-receiving hopper of stainless steel, a synchronous electric motor, an electronic frequency changer arranged to control the speed of said motor, and, optionally, a fixed-ratio gearbox arranged to be driven by said motor, and, optionally, an aluminium base, and an access cover comprised of at least two metal strips disposed face-to-face with each other.

Owing to this aspect of the invention, it is possible for the machine to be of relatively light weight.

According to a ninth aspect of the present invention, there is provided a method of spraying building material, comprising delivering fluid substance, obtaining from said substance being delivered data relating to said substance, and utilising said data.

According to a tenth aspect of the present invention, there is provided a machine for spraying building material, comprising a delivery arrangement for delivering fluid substance, and an obtaining arrangement for obtaining from said substance being delivered data relating to said substance, there being a utilising device serving to utilise said data.

Owing to these two aspects of the invention, it is possible, substantially simultaneously with the spraying itself to obtain and utilise such data. The data obtained may, for example, be the rate of delivery of the substance, whilst the utilising of the data may comprise one or more of displaying the data or information derived from the data, recording the data or information derived therefrom, and using the data to produce an audible and/or visible warning.

In order that the invention be clearly and completely disclosed, reference will now be made, by way of example, to the accompanying drawings in which :-

Figure 1 is a side view of a concrete spraying machine, Figure 2 is a perspective view of part of the machine,

Figure 3 is a diagrammatic, fragmentary view similar to Figure 1 of the machine, but partly in vertical section and with parts omitted for the sake of clarity,

Figure 4 is a detail of Figure 3, Figure 5 is a perspective view of parts of a hopper unit of the machine in a dismantled state,

Figure 6 is a diagrammatic, fragmentary view of an outflow duct of the machine,

Figure 7 shows a diagrammatic horizontal section through an access cover of the machine,

Figure 8 shows a section taken on the line VIII-VIII of Figure 3,

Figure 9 is a perspective view of an outlet end region of the outflow duct and of a control unit of the machine, Figure 10 is a view similar to Figure 1 but with parts of the machine omitted,

Figure 11 is a fragmentary, perspective view of a ramp for use with the machine, Figure 12 is a fragmentary side view illustrating a base unit of the machine being loaded onto a vehicle by way of the ramp, and

Figure 13 is a view similar to Figure 1, but fragmentary and with parts omitted, of a slightly modified version of the machine.

Referring to Figures 1 to 10, a spraying machine 50 has a hopper unit 1 comprised of an upper conical part la into which dry mortar or concrete is poured and a lower non- conical part lb. A rotating paddle 2 helps to ensure that the dry material flows into cavities 3 in a feeder disc 4. Material in the cavities 3 is blown out of the cavities by compressed air which is admitted through an aperture 5 in a rubber transfer plate 6. The rubber transfer plate 6 is pressed against the upper surface of the feeder disc 4 by means of hydraulic pistons 7 operated by screws 7a and pressing against a steel spreader plate 8 provided with two apertures 5' for entry of compressed air and 9' for exit of the material and the compressed air. The compressed air is supplied via a hose 60 leading to the aperture 5¹ from an elbow connector 62 at an aluminium box 64 containing a motor- operated control valve (not shown) for the compressed air which is supplied by a portable compressor machine (not shown) via a hose (not shown) to an elbow connection 66. The non-conical part lb of the wall of the hopper unit 1 is formed with a sectoral recess providing a hatch 13 for access to the disc 4 and the plates 6 and 8. The hydraulic pistons 7 react against an overhang 54 of the hatch 13. The material leaves the cavities through an aperture 9 in the rubber transfer plate 6 and the corresponding aperture 9' in the plate 8 and is blown through an outflow duct consisting of a hose connection 10, an air hose 11 connected to the connection 10, and an outlet nozzle 12 on the hose 11.

The lower edge ^one of the hatch 13 is sealed by means of a hatch cover 15 including a rubber seal 14 which partly rests against the circumference of the upper part of the disc

4, and partly is pressed hard against the correspondingly curved outer edges of the stationary plates 6 and 8. The cover 15 also includes two concentrically curved strip-form metal panels 15a and 15b, which are fastened together by screws 52 or any other convenient means. The rubber seal 14 is fastened, preferably by vulcanising or gluing, to the innermost panel 15b. The cover 15 has a hinge member 16 integral with one end of the outermost panel 15a and is of a curvature which matches that of the edges of the plates 6 and 8 and the disc 4. The other end of the cover 15 is provided with a strong hook 17 on the outer surface of the outer panel 15a designed to receive a locking bar 18 of a heavy-duty snap latch which operates by means of a lever action. This lever action presses the rubber seal 14 hard against the outer curved edges of the stationary plates 6 and 8 and simultaneously brings it to rest against the circumference of the upper part of the disc 4 until such time as the seal is so worn away by impinging material and by the rotation of the disc 4 that it no longer provides a proper seal. When this happens, the hatch cover 15 is simply released at one end by operating the locking bar 18 and swung outwards on its hinge 16. The innermost panel 15b carrying the rubber seal 14 is simply unscrewed from the outermost panel 15a and replaced by another unit consisting of an identical panel 15b and an identical seal 14.

When the rubber transfer plate 6 is so worn that air and material leakage are too great for efficient operation, the plate 6 must be replaced. The hinged hatch cover 15 allows easy access for this purpose since it is easily swung aside without the use of tools. The hatch cover 15 is also considerably lighter in weight than conventional hatch covers.

The hopper unit 1 can be easily separated from the base unit 19 of the machine 50. This results in a much reduced height of the machine and in a division of its total weight, both of which allow the entire machine 50 to be easily transported in a small van or medium-sized estate car. It also allows easy access to the feeder disc 4 and associated parts for servicing and/or replacement. For this purpose, a shaft 20 which simultaneously rotates the feeder disc 4 and the paddle 2 of the machine is provided with a bayonet lock 21 which allows the shaft to transfer load in one rotational direction, but which results in separation of the paddle 2 from the shaft 20 when rotated in the opposite direction. This action disconnects the paddle 2 from the underlying machinery and leaves the entire hopper unit free for removal from the base unit 19 by unscrewing nuts 22 on each of three screws on an upper surface of the base unit 19. The nuts 22 serve the purpose of readily releasably fastening the hopper unit to the base unit 19 and are provided with respective handles 23, which allow them to be operated without tools, and with clamping flanges. The non-conical part lb has its lower edge provided with three flat, hook-like, horizontal brackets 24. To mount the hopper unit on the base unit, the entire hopper unit is rotated about the axis of the shaft 20, so that the hooks of the hook-like brackets 24 embrace the shanks of the screws, the nuts 22 on which are then tightened to bring their clamping flanges down firmly upon those brackets . The machine 50 has a lifting eye 58 attached to the conical part la of the hopper unit 1 so that the machine 50 can be lifted by a crane or hoist. The lifting eye 58 is positioned so that, as the machine 50 is lifted off the ground, the machine does not tilt significantly, so that any material that may still be in the hopper unit 1 does not spill out.

The machine 50 is controlled, via an electrical cable 56, from a control box 25 the underside of which is shaped so as to fit over the nozzle 12, as shown in Figure 9. The box 25 is provided with a continuously adjustable air supply control 26, an on/off switch 27 which energises or de- energises the speed control circuitry of an electric motor 44 which drives the feeder disc 4, and a control 28 for continuously adjusting the speed of the electric motor 44 and hence regulating the feeding rate of the dry material to the hose connection 10 and the hose 11 leading to the nozzle 12. The adjustable air supply control 26 operates a motor-driven air valve situated at a convenient location on the machine. The on/off switch 27 controls the supply of electrical current to the electronic speed regulation circuitry (not shown) contained in the box 64. The adjustment of the rotational speed of the motor 44 by the control 28 is achieved by electronically altering the frequency of the alternating current supplying the motor 44 which is a brushless synchronous motor. The speed at which conventional machines operate is controlled by changing gears in a gearbox, or by using a variomatic belt-driven speed changer. Both of these arrangements are bulky, comparatively heavy, and mechanically complicated. The use of electronic frequency changing and a synchronous motor 44 allows a fixed- ratio gearbox 46 of simpler, lighter and more compact construction to be used. Furthermore, the machine 50 can be powered by an ordinary domestic single-phase power supply fitted with a 16 amp fuse.

In addition to these controls 26, 27 and 28 provided on the control box 25, the operator has control over the water supply by operating a stopcock 68 at the nozzle. The total weight of the machine 50 has been greatly reduced compared to conventional machines in a number of ways. Firstly, the material of the hopper is conventionally heavy gauge steel whereas, the present hopper is constructed of stainless steel. Apart from being easier to clean, the increased stiffness of stainless steel allows thinner and lighter gauges to be used. In the conical part la a gauge of 1.2 mm has been found to be sufficient and in the non-conical part lb, a gauge of 4 mm has been found to be sufficient. Secondly, the use of the electronic frequency changer which controls the speed of the motor 44 located in the base unit 19 allows a simple gearbox 46 to be used instead of the much bulkier and heavier speed-changing gear boxes or belt-driven variomats which are conventionally used. Thirdly, the resulting compactness of the motor 44 and the gearbox 46 allows them to be built into a housing 29 of the base unit 19 which can be constructed from an aluminium box 29a and an aluminium plate 29b. The box 29a has been found to be sufficiently strong when constructed from 3mm aluminium plate welded so as to form a box of approximately 750mm x 400mm x 180mm outer dimensions, and closed by a 10 mm thick aluminium plate 29b suitably drilled to accommodate the shaft 20, sundry necessary wires and other fittings, and fitted with two 30 x 50 mm massive aluminium beams 48 to which the electric motor and gearbox are fixed. The plate 29b is fastened to a flange 30 of the box 29a by screws at intervals around the perimeter, or any other suitable means. Fourthly, the hatch cover 15 is lighter in weight than conventional hatch covers and fifthly, the reduced total weight of the machine 50 allows lighter wheels 31 and 32 and axles to be used.

The total reduction in weight achieved by the above- described measures allows the construction of a machine with an output of around 401/min of sprayed concrete, but weighing no more than around 150kg. On detaching the hopper unit 1, the weight of the remaining base unit 19 is around 110kg. When it is desired to transport the machine, the base unit 19 can be easily loaded by one person into or onto a vehicle by rolling it on its wheels 31 and 32 up a ramp 33 shown in Figures 11 and 12 which is made from a single metal sheet bent upwards at its two longitudinal edges so as to provide vertical guide walls 40 suitably spaced apart by a horizontal section 42 to accommodate the width of the machine 50. This avoids the need for lifting equipment or for manual lifts to load the machine into or onto a vehicle for transportation. The length of the ramp to allow one less than averagely strong man, or a strong woman, to roll the wheeled section comfortably through a vertical distance of about 0.5m into or onto a vehicle, is about 1.8m. This length allows the ramp to be easily transported alongside the machine in small vans or medium-sized estate cars.

If is is desired to have data as to the composition of the wet mortar or concrete being sprayed, there is incorporated into the machine 50 instrumentation which allows the amounts of air, water, and dry material passing through the machine to be determined and which gives digital readouts (although analogue read-outs are possible additionally or alternatively) .

Sensors 70 and 72 to measure the rates of air and water supplies are inserted in the respective lines. Preferably, the sensor 70 measuring the rate of air flow to the openinig 5' is located proximal to the opening 5' and the sensor 72 for measuring the rate of water flow is located in the machine 50. The sensors 70 and 72 are in the form of windmill like devices in housings, and are rotated by the streams of fluids passing through them. The speeds of rotation of the windmills are converted electronically to provide a digital display of the measurements of the amounts of fluids passing through the machine per unit of time. To this end, the water stream is made to pass through a conduit 71 in the machine solely for measuring purposes, as this is otherwise unnecessary, the water supply to the conduit 71 being through a hose 73 and the water stream passing from the conduit 71 to the stopcock 68 through a hose 75.

The amount of dry material passing through the machine 50 is derived from the volume of the cavities 3 in the feeder disc 4 and the frequency of the power being supplied to the electric motor 44. Since the volume and number of the cavities 3 is fixed in any one machine, the feeding rate of dry material to the hose connection 10 depends virtually only on the speed of rotation of the feeder disc 4 which bears a direct relationship to the control frequency of the supply to the motor 44.

The amount of air being used has no bearing on the composition of the wet mixture sprayed, but it is a useful parameter in judging the force of the ejected mixture hitting the surface. It is also extremely useful for reproducing previous spray work.

All of the measured values are displayed on a device 74 mounted on top of the machine 50 and including a housing 76 provided with a transparent window 78 which allows digital meters of the device 74 to be easily seen and read. The actual placement of the display device 74 on the machine 50 is not critical, and is more a matter of convenience.

The machine 50 is provided with a handle 34 for moving the machine along the ground and to allow lifting of the castor wheel 31 over obstacles. The handle 34 is constructed from two pieces of strong pipe welded or otherwise joined together so as to form a T. The lower end of the T is drilled to accept a hinge bolt 35 which also passes through two parallel sides of an inverted channel piece 36 welded or otherwise fastened to the hopper wall. In its lowered position shown in Figure 1, the handle 34 hangs down at the front of the machine. When the handle is swung upwards, the base of the channel limits the movement of the handle so that the handle acquires a near horizontal position conducive to pulling or pushing the machine 50 and to lifting the castor wheel 31 over obstacles. In a modification shown in Figure 13, a sufficiently strong third horizontal lug 36a is provided immediately above two vertical lugs 36b so that, when the handle 34 is swung upwards, the third lug 37 limits the movement. The hinging of this handle considerably reduces the overall length of the machine, which is of importance when transporting it in or on a vehicle. The improvements described with reference to the drawings result in building material spraying machines which are considerably less bulky and lighter in weight than conventional machines, more easily transported, operated and serviced than conventional machines, and give considerable cost savings in that wear is reduced, and in that time, materials and energy are saved. In addition, personnel costs are reduced since the machines are easily operated and transported by one person with higher efficiency than conventional machines. In particular, there is:-

(i) easy access to the feeder disc 4 for its removal and replacement, and easy removal and replacement of the rubber transfer plate 6 and the rubber hatch seal 14, these being achieved particularly by the provision and construction of the devices 7, 7a and the hatch cover 15; (ii) easy division of the machine for transport and servicing purposes, this being achieved by the provision and construction of the bayonet lock 21 and the devices 22 to 24; (iii) the ramp 33 for easy loading of the machine 50 into or onto a vehicle, the ramp being usable because of the relatively low weight of the machine 50;

(iv) the provision of machine controls at the nozzle 12 itself, which gives the spray operator total control over: a) opening and closing of the air supply, which is provided by a separate compressor machine b) starting and stopping of the spray machine motor 44 c) the amount of air supplied to the machine 50 d) the rotational speed of the feeder disc 4, and hence the amount of dry material being supplied to the nozzle 12 e) opening and closing of the water supply f) the amount of water being supplied.

(v) the arrangement of the handle 34 so that it is collapsible, which reduces the overall length of the machine 50 and abuts a stop 36 or 36a, which enables lifting of the front of the machine 50;

(vi) the powering of the machine 50 by an ordinary domestic single-phase power supply, whereas conventional machines of similar capacity require a

3-phase supply because of their mechanical drives; (vii) the determination of the supply rates of the air, water and dry material and the display of these rates at the display device 74.

Claims

£ M£

1. A machine for spraying material, including an interior part to which access is required, and a cover openable to allow access to said interior part, said cover comprising an outer panel and an inner seal detachably connected to said outer panel.

2. A machine according to claim 1, wherein said cover further comprises an inner panel to which said inner seal is attached.

3. A machine according to claim 2, wherein said inner seal and said inner panel are detachably connected to said outer panel.

4. A machine according to any preceding claim, wherein said cover is readily openable to allow access to said interior part.

5. A machine according to claim 4, wherein said outer panel, at an edge thereof, is hingedly connected to an exterior surface of said machine.

6. A machine according to claim 4, wherein said outer panel, at an opposite edge thereof, is releasably attached to said exterior surface by means of a lever-action, snap latch.

7. A machine according to any preceding claim and further comprising a substantially horizontal feeder disc mounted so as to be rotatable about its own axis, cavities formed in an upper surface of said feeder disc and distributed around said axis for receiving said material, a stationary plate extending over part of said upper surface and formed with an entry aperture for conveying fluid and an exit aperture for the conveying fluid and the material conveyed thereby, said inner seal resting against part of the circumferance of the feeder disc and bearing firmly against a radially outer surface of said stationary plate.

8. A machine according to claim 7, and further comprising, between said stationary plate and said feeder disc, a stationary sealing plate of elastomeric material, said inner seal bearing firmly against a radially outer surface of said stationary sealing plate.

9. A machine according to any preceding claim, and further including a hatch allowing access to said interior part.

10. A machine according to claim 9, wherein a lower edge zone of said hatch is sealed by said cover.

11. A machine according to any preceding claim, and having a hopper unit, a base unit, and a readily releasable arrangement connecting said hopper unit detachably to said base unit.

12. A machine according to claim 11, wherein said hopper unit is of stainless steel.

13. A machine according to claim 11 or 12, wherein said base unit comprises an aluminium box.

14. A machine according to claim 11, 12 or 13 wherein said readily releasable arrangement comprises, on one of said base unit and said hopper unit, screws, on the other of said base unit and said hopper unit, brackets to co-operate with said screws, and nuts to co-operate with said screws.

15. A machine according to claim 14, wherein said nuts are provided with manually operable handles and clamping flanges .

16. A machine according to claim 14 or 15, wherein said brackets are flat, hook-like, horizontal brackets.

17. A machine according to any one of claims 11 to 16 as appended to claim 7, wherein said base unit includes a rotating shaft to which said feeder disc is fixed and which extends vertically upwards from said base unit into said hopper unit .

18. A machine according to claim 17, wherein said readily releasable arrangement includes a bayonet lock effective between said shaft and a rotary paddle retaining said hopper unit .

19. A machine according to any one of claims 11 to 18, wherein the overall height of said machine is greater than the height of said base unit and is greater than the height of said hopper unit.

20. A machine according to any preceding claim, and further comprising an outflow duct, and an actuating arrangement for controlling a plurality of functions of said machine, said actuating arrangement being located exteriorly of said duct in an outlet region of said duct.

21. A machine according to claim 20, wherein said plurality of functions includes supply of compressed air to said machine.

22. A machine according to claim 20 or 21, wherein said plurality of functions includes driving an electric motor.

23. A machine according to claim 22, wherein said electric motor is a synchronous electric motor.

24. A machine according to claim 23, wherein said synchronous electric motor is controlled by a frequency changer controlled by said actuating arrangement.

25. A machine according to any one of claims 22 to 24 as appended to claim 17, wherein said electric motor controls the speed of rotation of said shaft.

26. A machine according to claim 25, and further comprising a fixed-ratio gearbox interposed between said motor and said shaft .

27. A machine according to any one of claims 20 to 26 and further including an obtaining arrangement for obtaining data relating to said plurality of functions, there being a utilising device serving to utilise said data.

28. A machine according to claim 27, wherein said utilising device comprises a display device serving to display said data.

29. A machine according to any preceding claim, and further comprising a handle for use in manually pulling said machine over the ground or floor, said handle having an outer end for grasping by the puller and an inner end mounted for turning about a substantially horizontal axis, and an abutment disposed above said handle at a location outwardly of said inner end and limiting upward turning of said handle in order to allow the puller to lift the inner end of the handle relative to the ground or floor.

30. Apparatus comprising:- a machine as claimed in any one of claims 11 to 19 or any one of claims 20 to 29 as appended to claim 11, said base unit being wheeled, and a ramp device for use in wheeling said base unit, in a condition detached from said hopper unit, onto a vehicle.

31. A machine according to claim 30, wherein said ramp device includes, at its longitudinal edges, upwardly projecting guide walls preventing said base unit from falling off said ramp device.

32. A method comprising providing a machine for spraying material, detaching a hopper unit of said machine from a base unit of said machine, transporting said hopper unit and said base unit in a condition detached from each other, and reattaching said hopper unit to said base unit.

33. A method according to claim 32, wherein said detaching and said reattaching is performed manually without the use of a tool.

34. A method according to claim 32 or 33 and further comprising delivering fluid substance, obtaining from said substance being delivered data relating to said substance, and utilising said data.

35. A method according to claim 34, wherein said utilising comprises displaying said data.

36. A method according to claim 34 or 35, wherein said substance comprises dry material.

37. A method according to any one of claims 34 to 36, wherein said substance comprises compressed air.

38. A method according to any one of claims 34 to 37, wherein said substance comprises water.

39. A machine for spraying material, including an interior part to which access is required, and a cover readily openable to allow access to said interior part.

40. A machine according to claim 39, wherein said cover, at an edge thereof, is hingedly connected to an exterior surface of said machine.

41. A machine according to claim 40, wherein said cover, at an opposite edge thereof, is releasably attached to said exterior surface by means of a lever-action, snap latch.

42. A machine according to any one of claims 39 to 41, and further including a hatch allowing access to said interior part .

43. A machine according to claim 42, wherein a lower edge zone of said hatch is sealed by said cover.

44. A machine for spraying material, comprising a hopper unit, a base unit, and a readily releasable arrangement connecting said hopper unit detachably to said base unit.

45. A machine according to claim 44, wherein said hopper unit is of stainless steel.

46. A machine according to claim 44 or 45, wherein said base unit comprises an aluminium box.

47. A machine according to claim 44, 45 or 46, wherein said readily releasable arrangement comprises, on one of said base unit and said hopper unit, screws, on the other of said base unit and said hopper unit, brackets to co-operate with said screws, and nuts to co-operate with said screws.

48. A machine according to claim 47, wherein said nuts are provided with manually operable handles and clamping flanges.

49. A machine according to claim 47 or 48, wherein said brackets are flat, hook-like, horizontal brackets.

50. A machine according to any one of claims 44 to 49, wherein said base unit includes a rotating shaft to which a feeder disc is fixed and which extends vertically upwards from said base unit into said hopper unit.

51. A machine according to claim 50, wherein said readily releasable arrangement includes a bayonet lock effective between said shaft and a rotary paddle retaining said hopper unit .

52. A machine according to any one of claims 44 to 51, wherein the overall height of said machine is greater than the height of said base unit and is greater than the height of said hopper unit.

53. Apparatus comprising: - a machine for spraying material, comprising a hopper unit, a wheeled base unit, and a releasable arrangement connecting said hopper unit detachably to said base unit, and a ramp device for use in wheeling said base unit, in a condition detached from said hopper unit, onto a vehicle.

54. A machine according to claim 53, wherein said ramp device includes, at its longitudinal edges, upwardly projecting guide walls preventing said base unit from falling off said ramp device.

55. A machine for spraying building material, including an outflow duct and an actuating arrangement for controlling a plurality of functions of said machine, said actuating arrangement being located exteriorly of said duct in an outlet region of said duct.

56. A machine according to claim 55, wherein said plurality of functions includes supply of compressed air to said machine.

57. A machine according to claim 55 or 56, wherein said plurality of functions includes driving an electric motor.

58. A machine according to claim 57, wherein said electric motor is a synchronous electric motor.

59. A machine according to claim 58, wherein said synchronous electric motor is controlled by a frequency changer controlled by said actuating arrangement.

60. A machine according to claim 58 or 59, and further comprising a fixed-ratio gearbox interposed between said motor and a shaft.

61. A machine for spraying material, including a handle for use in manually pulling said machine over the ground or floor, said handle having an outer end for grasping by the puller and an inner end mounted for turning about a substantially horizontal axis, and an abutment disposed above said handle at a location outwardly of said inner end and limiting upward turning of said handle in order to allow the puller to lift the inner end of the handle relative to the ground or floor.

62. A machine for spraying material, having any one or more of the following features :- a material-receiving hopper of stainless steel, a synchronous electric motor, an electronic frequency changer arranged to control the speed of said motor, and, optionally, a fixed-ratio gearbox arranged to be driven by said motor, and, optionally, an aluminium base, and an access cover comprised of at least two metal strips disposed face-to-face with each other.

63. A method of spraying building material, comprising delivering fluid substance, obtaining from said substance being delivered data relating to said substance, and utilising said data.

64. A method according to claim 63, wherein said utilising comprises displaying said data.

65. A method according to claim 63 or 64, wherein said substance comprises dry material.

66. A method according to any one of claims 63 to 65, wherein said substance comprises compressed air.

67. A method according to any one of claims 63 to 66, wherein said substance comprises water.

68. A machine for spraying building material, comprising a delivery arrangement for delivering fluid substance, and an obtaining arrangement for obtaining from said substance being delivered data relating to said substance, there being a utilising device serving to utilise said data.

69. A machine according to claim 68, wherein said utilising device comprises a display device serving to display said data.