Applicator for applying a surface treatment

Abstract: An applicator for mounting on a vehicle for applying a surface treatment of tar and/or bituminous binder material reinforced with glass fibres, such an applicator comprising an open bottomed spray bar housing (1), a fan (16) for producing a downdraft in the housing, at least one spray bar (5,19) mounted on said housing and adapted to extend transversely of the direction of movement of the vehicle on which the applicator is mounted, a plurality of nozzles (6,20) spaced longitudinally along the spray bar for spraying binder material, means (10) for controlling said nozzles, a plurality of sources (14, 24-28) for dispensing cut glass fibres through said open bottomed housing to the surface of binder material previously sprayed from the spray bar nozzles during use of the applicator, said sources being mounted at locations spaced along a plane substantially parallel to said spray bar, such that the glass fibres are dispensed substantially evenly onto the surface of binder material previously sprayed from the spray bar nozzles.

Description: This invention relates to an applicator for mounting on a vehicle for applying a surface treatment of tar and/or bituminous binder material reinforced with glass fibres. GB-A-2 081 603 describes a surface dressing comprising a binder which is reinforced with chopped glass fibres with a suitable aggregate then being added to the thus coated substrate to be bound thereto by the same binder as has been reinforced with glass fibres. GB-A-2 121 853, from which the present invention proceeds, describes an applicator for attachment to a vehicle for applying a surface dressing of the type described in GB-A-2 081 603. The applicator comprises an open-bottomed housing containing at least one spray bar mounted to said housing for spraying binder material from a plurality of nozzles placed longitudinally on the spray bar housing to extend transversely of movement of the vehicle when mounted to said housing and means for depositing cut glass fibres from the glass fibre distributor through the open bottomed housing onto the surface of a layer binder material previously sprayed from the spray bar nozzles. See also the preamble of claim 1. A problem associated with the applicator disclosed by GB-A- 2 121 853 is providing an even layer of chopped glass fibres, and controlling the distribution of this layer over a first binder layer provided by a first spray bar. It has been found that the layer of chopped glass fibres is dispensed unevenly and indeed can be deposited on areas where there is no binder material. The unevenness gives a less than satisfactory surface treatment and the glass fibres which do not settle on the strip of binder applied are wasted, which is economically, as well as environmentally inefficient. A further problem with the device of the prior art is the circulation of air caused by the spray of bitumen in the applicator. It is inevitable that within the housing, a certain amount of bitumen spray is circulated in an updraft and attaches to the source of the glass fibre spray, and/or the glass fibre feeders. Without frequent maintenance and cleaning of the glass fibre sources and feeders, the sources and feeders will clog up and operation of the applicator will be halted. The present invention seeks to overcome the problems of the prior art described above. Thus the present invention provides an applicator for mounting on vehicle for applying a surface treatment of tar and/or bituminous binder material reinforced with glass fibers, such an applicator comprising an open bottomed spray bar housing, at least one spray bar mounted on said housing and extending transversely of the intented direction of movement of the applicator when mounted on the vehicle, a plurality of nozzles spaced longitudinally along the spray bar for spraying binder material, means for controlling said nozzles, means for dispensing cut glass fibres through said open bottomed housing to the surface of binder material previously sprayed from the spray bar nozzles during use of the applicator, said dispensing means being located behind the spray bar with regard to the intended direction of movement of the applicator, the means for dispensing the cut glass fibres comprising more than two sources mounted in said housing and mounted at locations spaced along a plane substantially parallel to said spray bar. The applicator is characterized in that it additionally comprises a means for producing a downdraft within the housing. The plane along which the plurality of glass fibre sources are located is preferably a single straight line. Such an arrangement allows the plurality of sources to be powered easily by a single power supply but to operate individually. The plurality of sources for the glass fibre are preferably similar in number, for example ± 1 or 2 of the number of spray bar nozzles. Most preferably, the number of glass fibre sources are identical to the number of spray bar nozzles. Such an arrangement allows the plurality of nozzles and glass fibre sources to be arranged such that each glass fibre source is in substantially the same plane of the applicator in the direction of motion of the vehicle as an associated nozzle. Preferably, each pair of a nozzle and an associated glass fibre source is individually controllable. The applicator optionally contains a second spray bar housing and spray bar mounted thereto mounted behind the source of glass fibre. The second spray bar, which is advantageously controllable independently of the first spray bar will usually have fewer nozzles than the first spray bar, and these nozzles are preferably in interleaving planes in the direction of motion of the vehicle to the nozzles of the first spray bar. Desirably, the invention also comprises an applicator according to the invention which additionally comprises a means such as a fan for producing a downdraft in said applicator to distribute said fibres more evenly into the wet bitumen film. The downdraft created by the fan reduces the circulation of binder spray from the nozzles of the applicator, and thus protects the glass fibre choppers of the applicator from being clogged up with binder. The downdraft may be produced by a fan located above the source of the glass fibres and such a fan may be powered by any suitable means, e.g. electrically. Preferably, the glass fibre source comprises a supply of a tow of glass fibre, means for supplying the tow to a chopper, and means for driving the chopper. The chopper and supply may be of a conventional type, for example a rotary pneumatically powered cutter which drags in the tow of glass fibres which are chopped into short lengths, for example 20 to 30 mm, which then fall perpendicularly onto a layer of binder provided by the first set of spray bar nozzles. However, in a preferred embodiment of the invention, the glass fibre source comprises a novel chopper comprising a cylindrical cutter drum rotatable about its axis on a driveshaft, the drum comprising axially extending cutter blades protruding above the periphery of the drum at circumferentially spaced intervals, and a pressure roll for feeding a tow of glassfibre between said pressure roll and said drum, the cutter drum being continuously rotatable and the pressure roll being mounted on a pivotal arm which is individually pivotal by means of a fluid pressure operated piston and cylinder arrangement onto the surface of the cutter drum. When the applicator of the invention, optionally fitted with a fan to produce a downdraft, contains a plurality of the novel choppers, the cutter drums of said choppers may be mounted on a single driveshaft, which is continuously rotated, and the movement of the individual pressure rolls of said choppers onto and away from the cutter drum may be individually controlled. With such an arrangement, the width of the applicator across which glass fibres are sprayed is controlled by selecting which pressure rollers are positioned onto their corresponding cutter drums, and which are lifted away from said drums. The invention will be further described, by way of example, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a side view of one embodiment of an applicator according to the invention; Figure 2 is a perspective view of an array of choppers for use in the applicator of the invention; Figure 3 is a side view of a chopper of Figure 2; Figure 4 is a plan view of a cutter drum of the chopper of Figure 3; and Figure 5 is a side view of the chopper of Figure 3, from the other side. Referring to Figure 1 there is shown a spray bar housing 1 which has an open bottom and is provided with a plurality of nozzles for ejecting conical sprays of binder onto a surface 2 being dressed. In this embodiment an attachment bar 4 is shown mounted to the forward side of the housing 1 for securement of the applicator to the rear of a vehicle, conventionally a tanker from which liquid binder is supplied. A first spray bar 5 comprising a plurality of longitudinally spaced spray nozzle heads 6, from which conical jets of spray 12 of binder are projected, is mounted in the forward part of the housing 1. The heads 6 are provided with valves 10 individually connected to a supply conduit 8 connected to a binder supply hose. The valves 10 of the individual nozzles control the supply of binder through each spray nozzle. The applicator housing 1, in its central portion, contains a plurality of choppers 14, the choppers 14 each being fed a tow of fibreglass which is chopped to produce short glass fibres, which fall substantially perpendicularly onto the surface 2 which has been coated with a first layer of binder from the nozzle 6. Situated above the plurality of choppers, is a fan 16 for the production of a downdraft of air in the housing 1, in order to reduce upward circulation of the binder spray 12 and evenly to distribute the spray of chopped glass fibres 18 onto the surface. In the preferred embodiment of the invention illustrated by Figure 1, a second spray bar 19 comprising an array of longitudinally spaced nozzles 20 distributes a further layer of binder over the surface 2 which has been sprayed. The nozzles 20 are located in spaced planes (parallel to the direction of movement of the vehicle) between the nozzles 6, thereby producing a more even surface treatment. Figure 2 shows in more detail part of an array of the plurality of choppers 14. A support bracket 24 is mounted to the applicator housing. The said bracket supports a drive shaft 26 onto which several cutter drums 28 are mounted. The choppers and their operation will be better understood by reference to Figure 3. Figure 3 shows the side view of an individual chopper. A support bracket 24 supports the cutter drum 28 as illustrated in Figure 2. The bracket 24 also supports a hinged arm 30 pivoted by a retaining means 32. The arm 30 contains a pressure roll 34 and a feed roll 36. In use, a tow of glass fibres 38, fed through a conduit 40 from a source (not illustrated) is passed into the nip of the pressure roll 34 when it is contact with the drum 28, and feed roll 36. The arm 30 is held in place by a piston and cylinder arrangement 42 fixed to the support bracket 24. The cylinder is connected to a suitable hydraulic or pneumatic supply. Upon actuation, the arm 30 moves about pivot 32 to bring the pressure roll 34 into contact with the cutter drum 28. In operation, the cutter drum 28 will be continuously rotating, thus imparting rotation to pressure roll 34, when it is in contact with the drum 28, and in consequence pulling the tow of glass fibres 38 over the cutter drum, causing the tow of fibres to be chopped by the cutter blades 44. Figure 4 shows a cutter drum in further detail. The drum 28 is mounted on a drive shaft 26. Cutter blades 44 are held in axially extending slots in the surface of the drum. The blade 44 is retained in the slot by a retainer plate 46 and by an inturned rim 48 at one end and a bush 50 with an inturned rim 52 at the other. The bush 50 is fixed to the driveshaft by a retaining screw (not illustrated) which can be loosened, allowing the bush 50 to be moved along the drive shaft, allowing removal and replacement of the blades 44 and plates 46 from the cutter drum without the requirement to remove the drum from the drive shaft. Figure 5 shows the opposite side view to Figure 3 showing piston 42 fixed by fixing means 56 to the arm 30. The Figure also shows a bush 54 mounted on the drive shaft 26 to stop lateral movement of the cutter drum 28 on the opposite side of the bracket 24. In the chopper illustrated, the feed roll 36 is mounted on an eccentric stub shaft 58 on a lockable rotatable support 60, in order that the position of the feed roll 36 may be adjusted relative to the pressure roll 34. The binder as applied in use of the applicator of the invention is a conventional tar or bitumen emulsion binder with tar, bitumen or a tar and bitumen blend being used as convenient. Whereas normally applied hot, for example, using K170 bitumen which is a normal 70% bitumen emulsion, it can also be applied cold, for example, with K160 which contains 60% bitumen. In a particular embodiment, the operation of the spray bars is arranged so that a suitable thickness of bitumen is applied when the vehicle on which the applicator is mounted is moved forwardly at a speed of 1 to 2 km per hour. The invention thus provides an applicator which can lay a more even distribution of glass fibres in a surface treatment than applicators of the prior art. Furthermore, through the use of individually operable spray nozzles and associated glass fibre sources, controlled widths of a surface treatment may be efficiently laid by the applicator.

Claims: An applicator for mounting on a vehicle for applying a surface treatment of tar and/or bituminous binder material reinforced with glass fibers, such an applicator comprising an open bottomed spray bar housing (14), at least one spray bar (5, 19) mounted on said housing and extending transversely of the intended direction of movement of the applicator when mounted on the vehicle, a plurality of nozzles (6, 20) spaced longitudinally along the spray bar for spraying binder material, means (10) for controlling said nozzles, means (4) for dispensing cut glass fibres through said open bottomed housing to the surface of binder material previously sprayed from the spray bar nozzles during use of the applicator, said dispensing means being located behind the spray bar with regard to the intended direction of movement of the applicator, the means for dispensing the cut glass fibers comprising more than two sources (24-60) mounted in said housing (1) at a plurality of locations spaced at intervals across the width of said housing (1) between its extremities, along a plane substantially parallel to said spray bar, characterized in that the applicator additionally comprises a means (16) for producing a downdraft within the housing (1). An applicator according to claim 1 characterized in that the number of sources of glass fibers is equel to the number of spray bar nozzles. An applicator according to claim 2, characterized in that each pair of a nozzle and an associated glass fibre source is individually controllable. An applicator according to any one of the preceding claims characterized in that a second spray bar(19) is mounted on said housing to extend substantially parallel to said dirst spray bar (5) behing the source (14) of glass fibre. An applicator according to claim 4, characterized in that the second spray bar (19) is controllable independently of the first spray bar (5). An applicator according to claim 4 or 5, characterized in that the nozzles (20) of the second spray bar (19) are in interleaving planes in the direction of motion of the vehicle to the nozzles (6) of the first spray. An applicator according to claim 1, characterized in that the downdraft is produced by a fan (16) located above the source of the glass fibres. An applicator according to any one of the preceding claims characterized in that each source of glass fibres is a chopper comprising a cylindrical cutter drum (28) rotatable about its axis on a driveshaft (26), the drum comprising axially extending cutter blades (46) protruding above the periphery of the drum at circumferentially spaced intervals, and a pressure roll (34) for feeding a tow of glassfibre between said pressure roll and said drum, the cutter drum being continuously rotatable and the pressure roll being mounted on a pivotal arm (30) which is individually pivotal by means of a fluid pressure operated piston and cylinder arrangement (42) onto the surface of the cutter drum. An applicator according to claim 8, characterized in that the arm (30) of each chopper additionally comprises a feed roll (36) in a position such that a tow of glassfibre is retainable between the pressure roll (34) and said feed roll.

Inventors: HIGGINSON PHILIP JOHN, HIGGINSON, PHILIP JOHN
Applicants: COLAS SA, COLAS S.A.
Application year: 1991
Main classification: E01C19
IPC codes: E01C19, E01C23, B26D7, B26D1