MOBILE WORK STATION FOR ASSEMBLING AND LAYING REINFORCING BARS

Abstract: A mobile work station, for the assembling and laying of pavement reinforcing bars, comprising a wheeled chassis (6, 7) adapted to travel a route along which a pavement is to be laid and carrying a longitudinal rod guide and spacing means (23) extending transversely of the chassis at or towards the front thereof. The chassis having an open topped magazine (15) adapted to hold a quantity of transverse rods (16) situated aft of said guide and spacing means, and apron means (20, 21) extending rearwardly and downwardly from said magazine over which a reinforcing mesh ribbon may slide for deposition behind the chassis as the chassis moves ahead.

Description: MOBILE WORK STATION FOR ASSEMBLING AND LAYING REINFORCING BARS TECHNICAL FIELD This invention relates to the construction of reinforced concrete roads, and, in particular, to the emplacement of the reinforcing steel in the pavement or surface layer of the road. The invention is well adapted for use in the construction of long roads such as inter-city highways. BACKGROUND Conventionally, roads of the kind in question comprise a foundation layer, the so-called sub-base, usually of un-reinforced concrete, and the pavement or so-called base slab, which is reinforced, and is poured directly onto the sub-base. Typically, the base slab is reinforced by a rectangular grid of steel reinforcing rods comprising a plurality of spaced apart longitudinal rods extending in the direction of the road and a plurality of spaced apart transverse rods extending athwart the longitudinal rods and tied thereto at each crossing point in the mesh. The longitudinal rods are individually fairly short, say 12 metres long, but successive longitudinal rods are spliced together, that is to say, overlapped and tied to each other, to form a continuous ribbon of mesh extending along the road. That ribbon is supported from the sub-base by plastic or other bar chairs to ensure that the reinforcing is at the correct altitude in the finished pavement. Hitherto, the mesh ribbon has been formed in-situ by a gang of steel fixers by hand. This not only involves manhandling all the steel into place and tying the individual rods together while stooped over double, but also requires the preparatory steps of marking the edge of the pavement on the sub-base with a chalk line and spot marking the location of the individual transverse rods with paint to ensure that the fixers install the reinforcement to specification. The work is labourious and time consuming. Typically a gang of twelve workers can put the reinforcement in place for 200 to 250 metres of two lane pavement per day. An object of the present invention is to facilitate the emplacement of the steel rods and largely eliminate the need for preparatory marking of the sub-base. The invention achieves that object by providing a mobile work station that, in its preferred embodiments, enables the ties to be made without stooping to the same extent as before, greatly reduces the manhandling of the rods, and substantially ensures that the final mesh is laid to specification without the need for spot marking the sub-base. SUMMARY OF INVENTION The present invention consists in a mobile work station, for the assembling and laying of pavement reinforcing bars, comprising a wheeled chassis adapted to travel a route along which a pavement is to be laid and carrying a longitudinal rod guide and spacing means extending transversely of the chassis at or towards the front thereof, an open topped magazine adapted to hold a quantity of transverse rods situated aft of said guide and spacing means, and apron means extending rearwardly and downwardly from said magazine over which a reinforcing mesh ribbon may slide for deposition behind the chassis as the chassis moves ahead. Preferably said wheeled chassis is adapted to be towed by a truck or other prime mover or alternatively is an integral part of a self propelled vehicle Preferably a welding station is located aft of said magazine for welding said transverse rods to said reinforcing mesh ribbon. BRIEF DESCRIPTION OF THE DRAWINGS By way of example, an embodiment of the above described invention is described in more detail hereinafter with reference to the accompanying drawings. Figure 1 is a diagrammatic plan view of a mobile work station according to a first embodiment of the invention. Figure 2 is a side elevation of the work station of figure 1 partly sectioned on line 2-2 of figure 1. Figure 3 is a sectional view of the station of figure 1 taken on line 3-3 of that figure. Figure 4 is a detail perspective view of an end portion of a longitudinal rod guide and spacing means, being a component of the station of figure 1. Figure 5 is a diagrammatic plan view of a mobile work station according to a second embodiment of the invention. Figure 6 is a side elevation of the work station of figure 5. Figure 7 is an enlarged side elevation view of the welding station on the work station shown in figure 6. Figure 8 is an enlarged side elevation view of the welding head detail of the welding station shown in figure 7. MODE OF CARRYING OUT INVENTION In a first embodiment of the invention as shown in Figures 1 to 4, the wheeled chassis carrying the other components of the work station is in the form of a trailer adapted to be towed behind a rod supply truck, the rear of which is shown at 5. This is preferred, but in other embodiments the chassis may be an integral part of a self propelled vehicle. The illustrated chassis comprises a steel frame, comprising longitudinal members 6 and transverse members 7, supported by two front road wheels 8 and two rear road wheels 9. It is furnished with a short, central towing boom 10 whereby it may be hitched to the truck 5 so as to trail closely behind the truck. The front wheels 8 are free swivelling caster wheels. The rear wheels 9 are also able to swivel, but in their case they may be held at any selected swivel angle by means of trailing links 11 extending from the wheel axles to a steering rod 12 movable longitudinally of itself in bearing mounts 13. The longitudinal position of the steering rod 12 may be adjusted by means of an axially fixed steering wheel having an 15 internally threaded hub engaged with an externally threaded end portion of the rod 12. Thus, adjustment of the steering wheel 14 from time to time, as may be needed, enables the trailer to closely follow the truck 5 as the latter follows the usually gently curving route of a highway or the like. A longitudinal rod guide and spacing means 23 extends athwart the station close to the front thereof. In this instance those means comprise an I beam lying on its side with a series of slots 14 cut into its upwardly projecting flanges. These guide and spacing means 23 ensure that longitudinal rods extending from the supply truck 5 and lodged in the respective slots 14 are thus spaced and positioned as needed to suit the reinforcing ribbon that is to be formed. If desired the spacing of the slots 14 may be considerably less than that required in any instance, so that only selected slots 14 would be used in each instance to suit the particular reinforcement specification. It will also be appreciated that these guide and spacing means may take many other forms, for example they may comprise a linear array of tubes, through each of which a rod may extend, or they may be a comb-like structure with a multiplicity of upstanding fingers. In short, the guide and spacing means may be any device adapted to maintain predetermined spacings between a plurality of rods while allowing the rods to be drawn through or over the device. A magazine 15 is provided immediately behind the guide and spacing means 23 adapted to hold a quantity of transverse reinforcing rods 16. That magazine is merely a recess defined by a fabricated framework of upright posts 17 and floor rails 18. The posts 17, in this instance also serve as struts for the support of the guide and spacing means 23 and the front cross-member 19 of apron means described below. As well as the said cross-member 19, the apron means comprise a plurality of longitudinal members 20 and further cross-members 21 , supported from the chassis by posts 22 of various lengths. The apron means provide an upper surface on which a mesh ribbon may slide. That surface extends rearwardly and downwardly from the rear rim of the magazine recess to near the ground level behind the mobile work station. For the convenience of the steel fixers a platform (not shown) may be provided comprising planks resting on the boom 10 and forwardly projecting cantilevers (not shown) at the front corners of the chassis, and extending from side to side of the work station. Also a bench type seat may be provided extending along and above the guide and spacing means 23. The operation of the first embodiment is as set forth below. At start up, a short length of mesh would be formed by the former normally used manual method so as to overlie the apron means and maybe extend for a short distance behind the trailer. As is customary the ends of the longitudinal rods would be staggered so that all splices do not line up across the width of the pavement. A quantity of transverse rods would be loaded into the magazine recess and a quantity of longitudinal rods may be loosely spread upon the back of the truck 5. A row of fixers standing on the said platform may draw individual longitudinal rods towards them themselves, place them in selected slots 14 and splice them as needed to the longitudinal rods of the previously made mesh ribbon. Then the truck is advanced slowly by an amount equal to the required longitudinal spacing of the transverse rods. The fixers, acting in concert, then lift a transverse rod from the magazine and tie it to the longitudinal rods extending across the mouth of the magazine recess. The truck then moves forward another pitch distance and a further transverse rod is tied in place. So the operation proceeds, with the finished ribbon, having mesh lateral members 3 and mesh stringers 4, being laid upon the sub-base behind the trailer as the apron means move from under the newly formed ribbon on those means. As the newly made ribbon moves slowly downwardly towards the sub-base behind the apron means (there is no horizontal movement between the sub-base and the ribbon as a whole), it is relatively easy for a person or persons to position bar chairs where needed to receive the gently descending mesh In a second embodiment of the invention as shown in Figures 5 to 8, a mobile work station is shown similar to the first embodiment, however with the addition of an automated welding station located on the mobile work station For ease of reference the second embodiment utilises the same reference numerals for like components as the first embodiment The automated welding station comprises of six welding devices 30 positioned in-line athwart the chassis of the mobile work station aft of the spacing means 23 The welding devices 30 may be of any suitable type, such as metal inert gas (MIG) or resistance welding devices The provision of the automated welding station is to eliminate the need of the fixers to tie transverse rods to the longitudinal rods A load ramp 31 allows for transverse rods to be fed from magazine 15 into conveyor 32 which is adapted to carry the transverse rods to the welding station The conveyor 32 is of an endless belt type provided with carrier members 33 for carrying the transverse rods to the welding station Each welding device 30 has welding head 34 which is mounted to a carriage assembly 35 by means of an actuator(or ram) 36 The carriage assembly 35 allows for restricted positional movement of the welding head 34 both longitudinally and transversely with respect to the chassis of mobile work station The ram 36 allows for welding head 34 to be operably moved upwards and downwards The operation of the second embodiment is as set forth below At start up as in the first embodiment, a short length of mesh would be formed by the former normally used manual method so as to overlie the apron means and maybe extend for a short distance behind the trailer As is customary the ends of the longitudinal rods would be staggered so that all splices do not line up across the width of the pavement A quantity of transverse rods would be loaded into the magazine recess and a quantity of longitudinal rods may be loosely spread upon the back of the truck 5. One or more fixers standing on the said platform (same as in the first embodiment) may draw individual longitudinal rods towards them themselves, place them in selected slots 14 and splice them as needed to the longitudinal rods of the previously made mesh ribbon. Then the truck is advanced slowly by an amount equal to the required longitudinal spacing of the transverse rods. A transverse rod from the magazine 15 is carried by conveyor 32 to a position above the in-line welding heads 34. The rams 36 of each welding head 34 would then raise upwardly thereby raising both the welding head 34 and lifting bracket 37 which projects therefrom. Lifting bracket 37 engaging and supporting the transverse rod such that it may be welded to the longitudinal rods. Subsequent to this welding operation the ram 36 and therefore the welding head 34 is lowered to allow positioning of the next transverse rod. The truck 5 then moves forward another pitch distance and a further transverse rod is conveyed by conveyor 32 into place above the welding heads 34 prior to being welded. In use, it may preferably be that all six welding heads are used in-line to weld a transverse rod to the longitudinal rods. Alternatively, it may be that only three welding heads (ie every second welding head) is used for one transverse rod, and the alternate three welding heads are used for the next transverse rod and so on. Control and sensing means (not shown) may be used to control the operation of the conveyor 32 and the welding devices 30 as transverse rods are brought into position for welding . Preferably such control and sensing means may be in the form of a personal computer, program logic control unit or the like operably linked to the various components. The transverse spacing of welding heads 34 and their longitudinal positioning can be adjusted by movement of carriage assemblies 35 in order to suit different mesh ribbon sizes and operating conditions. Each carriage assembly 35 comprising a longitudinal carriage 39 for movement in a longitudinal direction of the chassis, and a transverse carriage 40 for transverse movement. Positioning of the carriage assemblies 35 may be manual or alternatively may be automated by incorporation of a drive means (not shown) which preferably is connected to the earlier described control means. The use of the automated welding station in this second embodiment would reduce the number of fixers required for operation as compared to the first embodiment of the present invention. Power requirements for the automated welding station and control and sensing means may be supplied by an electrical power generator (not shown) situated on the chassis or alternatively on truck 5. In a further not shown embodiment additional welding devices may be employed on the mobile work station to butt weld lengths of successive longitudinal rods together as they are placed in selected slots 14 of the guide and spacing means 23, thereby replacing the manual splicing method.

Claims: CLAIMS 1 A mobile work station, for the assembling and laying of pavement reinforcing bars, comprising a wheeled chassis adapted to travel a route along which a pavement is to be laid and carrying a longitudinal rod guide and spacing means extending transversely of the chassis at or towards the front thereof, an open topped magazine adapted to hold a quantity of transverse rods situated aft of said guide and spacing means, and apron means extending rearwardly and downwardly from said magazine over which a reinforcing mesh ribbon may slide for deposition behind the chassis as the chassis moves ahead 2 A mobile work station as claimed in claim 1 , wherein said wheeled chassis is adapted to be towed by a truck or other prime mover 3 A mobile work station as claimed in claim 1, wherein said wheeled chassis is an integral part of a self propelled vehicle A mobile work station as claimed in claim 1 , wherein a welding station is located aft of said magazine for welding said transverse rods to said reinforcing mesh ribbon A mobile work station as claimed in claim 4, wherein said welding station comprises a plurality of welding devices

Inventors: BEYERS LEONARD FRANCIS, BEYERS, LEONARD, FRANCIS
Applicants: BEYERS LEONARD FRANCIS, BEYERS, LEONARD, FRANCIS
Application year: 1997
Main classification: E01C23
IPC codes: E01C23