The present invention relates to methods and apparatuses for delivery of materials such as but not limited to aggregates and more particularly relates to an improved method for delivery of such aggregates from a spreader assembly and a system for controlling that delivery. The invention further relates to an attachable assembly for fixing to a vehicle having a source of granular material and the like and a control system for controlling the delivery of the material from the assembly.
Aggregates are widely used globally in pavement and road construction either for providing a road or pavement base or a durable wear surface which stands up to heavy traffic wear. One method of road construction involves preparing a sub grade surface, coating that sub grade with a layer of bitumen or the like and spreading gravel, metal aggregate road base or the like over the surface of the bitumen. This process is carried out partly by machine and partly by human labour in conjunction with the machine and has been used globally in road pavement constructions for many years. In large scale surfacing operations, machines are used which include a rear hopper from which is discharged the aggregate for the purpose of the surfacing. Due to the high cost of materials it is important to minimise wastage of pavement materials and particularly aggregates to maintain economies. This has proven to be difficult according to the prior art methods, as the use of manual labour in part of the process leads to inaccuracies in the distribution of the materials. Not only is there a high labour cost component when manual input is employed but also a high wastage component due to human error in material spreading.
In road construction and resurfacing it is highly desirable that the correct design volume of resurfacing aggregate is applied for economic and safety reasons. If too much aggregate is deposited on a surface, apart from the economic waste, there is a safety hazard from gravel mounds which often result from manual spreading. The prior art apparatuses have not, provided an aggregate discharge assembly which can be accurately controlled to deliver an accurate design quantity of material from a hopper and which may be calibrated and adjusted to compensate for assembly and operation parameters which influence discharge rate and quantity.
The present invention provides an improved apparatus and method for the spreading of construction materials such as aggregates in such applications as, but not limited to road pavement construction. More particularly, the invention provides an apparatus and method for the automated and controlled delivery of construction materials particularly in road pavement surfacing. The invention operates to accurately spread granular material such as but not limited to aggregate, according to a predetermined rate on to a surface such as a road pavement or the like. The invention further provides an apparatus which is capable of computer control of both small and large material delivery jobs and which removes the inaccuracies of operation of the known equipment and provides economies by reduction of human labour and elimination of materials losses caused by oversupply per unit area.
In one broad form the present invention comprises:
Preferably the control means is a computer.
In another broad form the present invention comprises:
In another broad form the present invention comprises:
According to a preferred embodiment, the material delivered by said apparatus is road pavement aggregate which is delivered under gravity from said hopper via adjustable gates: which may be adjusted to accommodate a design width for a job and weight per unit area. Preferably, said adjustable gate/s controls the size of an opening from which said aggregate is discharged wherein the size of the opening is adjusted in response to predetermined parameters such as apparatus speed over the ground and quantity of aggregate to be delivered in order to maintain a predetermined volume of aggregate per unit area.
In one broad form of the method aspect, the present invention comprises:
According to a preferred embodiment, the method comprises the further step of converting said input to a mechanical action thereby allowing at least one gate on said hopper to adjust responsive to said at least one input parameter so that said predetermined amount of material is discharged from said apparatus.
According to a preferred embodiment said at east one parameters may include, discharge rate of said material from said hoper in m3/unit area, speed of said apparatus, dimensions of said hopper opening, spread rate in kg/m2.
According to one embodiment the spread rate may be adjusted 0.5 kg per m2 at any time from minimum to maximum settings. Preferably, the apparatus is adapted as an attachment for mounting to the rear of a tipper truck
In another broad form the present invention comprises:
According to a preferred embodiment, said mechanical activity is the adjustment of one or more gates to adjust an opening in a hopper. Preferably the attachment is adapted to attachment to a vehicle such as a truck
In its broadest from the present invention comprises:
In another broad form the present invention comprises:
Preferably the input parameter or parameters are received and processed by a computer.
In another broad form the present invention comprises;
In a further broad form of a method aspect the present invention comprises:
The present invention will now be described in more detail according to a preferred but non limiting embodiment and with reference to the accompanying illustrations; wherein,
The invention will now be described in detail according to one embodiment, in its application to controlled spreading of road and pavement surfacing. It will however, be appreciated by persons skilled in the art that the spreader apparatus, control system and method of operation may be adapted to applications other than road and pavement surfacing.
In a typical road surfacing operation, a spreader, which will normally include a hopper for receiving and holding a road or pavement construction material such as an aggregate, will be preferably detachably attached to the rear of a tuck or other source of material supply by means of pin connections, bolts or nuts or alternative form of connection. The truck will be pre loaded with a supply of a flowable material such as but not limited to road base, aggregate (such as used in road surfacing operations) or other paving material. The material will be required to flow upon elevation of a tipper so granular materials are preferred such as aggregates, road bases sands and the like. The material to be spread as road base or on a pavement surface will be typically funnelled from a tipper into the hopper. The hopper receives and retains material delivered from the tipper for discharge via the spreader box.
Referring to
An operator will stand on platform 4 (as shown in
Assembly 1 further comprises a gate assembly 9 which is preferably air actuated but could be hydraulically operated. Gate assembly 9 may comprises a single gate or an array of separate gates individually operable. As shown in
Referring to
Gate 37 which is pivotally attached at hinge 39. Gate 37 is operably connected to adjustable air actuated cylinder 40 to enable alteration of the size of a discharge opening 38 through which a material such as aggregate 32 fed into hopper 31 thence spreader box 33 will be discharged from assembly 30. Cylinder 28 is preferably an air operated actuator or electric actuator. Alternatively, the cylinder may be hydraulically operated. Gate 37 is actuated by means of pneumatic rams 41 which is responsive to an output from PLC which in turn responds to an input parameter as will be described in more detail below. Ram 41 is either directly or indirectly linked to gate 37. As shown in
Assembly 30 further comprises a screeding assembly 47 comprising a downwardly depending strut 48 connected at one end to pivoting hinge 49 via pin 50. Arm 51 is also pivotally attached at one end to hinge 49 and at the other end to electrically actuated cylinder 53 via pin connection 52. Electrically actuated cylinder 53 is also linked to the PLC. Cylinder 53 includes ram 55 capable of movement in the direction of arrows 56 and 57. When ram 55 moves in the direction of arrow 56 strut 48 moves about pin 50 causing screeding assembly 47 to move in the general direction of arrow 58. Screeding assembly 47 can therefore move forwards or backwards. This enables the depth of the layer of discharged material to be adjusted.
In the case where bitumen is laid and is covered with gravel/aggregate/road base, to ensure that the vehicle does not travel over the freshly laid bitumen the vehicle may discharge the surfacing gravel/aggregate/road base, as it reverses in the direction of arrow 60a This ensures that the vehicle travels only on the discharged gravel/aggregate/road base, and not on the bitumen.
Screeding assembly 47 trails discharge chute opening 38 and maintains aggregate 32 at a predetermined thickness. The clearance distance d between screeding assembly 47 and ground surface 58 will dictate the thickness of the material 32.
The second program allows setting of truck parameters. Road speed is the critical parameter which is a function of the product of tyre circumference, differential ratio and road speed pulses/pulses per revolution. A third program allows for gate calibration which is required daily to establish if the spread rate delivered is commensurate with the spread rate prescribed. This is carried out by performing spread rate and mat tests prior to commencing a job. A fourth program allows loading of truck operation parameters. An aggregate size parameter is loaded by an operator. This parameter will be the staring point for determination of the remaining operating parameters which must accommodate aggregate size. The operation program is loaded with parameters which correspond to aggregate size. The spread rate weight is selected by the operator and converted to a raw proportional gate position. This result is then compensated for by the tilt feedback value. The proportional gate tilt compensated position is then calculated by a ratio of the raw proportional gate position and the truck tilt angle. The road speed compensated value is then calculated by a ratio of the proportional gate tilt compensated position and the calculated road speed. This result provides the operating set value for the proportional gate position. The set value then provides an accurate repeatable spread rate of aggregate on the ground.
The operator console screen displays operating parameters, truck operating status, selected aggregate recipe and weight, recipe details and error or fault messages.
The proportional gate position is controlled by the calculated set value compared to the position feedback signal. The comparison result will activate either an open or close command signal for the gates. Gates 11-19 are each activated by individual selector open and close switches which actuate solenoids connected to each drive cylinders for each gate. Timed pulse open signal opens solenoid valves for each material gate.
In use, the operator stands on the operator platform and selects the required amount of aggregate. Next, gate assemblies are opened in accordance with a corresponding input parameter or parameters. The operator console is preferably push button digital operation. Once the gate assemblies are set with reference to the kglm2 discharge rate set for a particular job, aggregate is fed into the hopper and eventually onto a road surface. A speed sensor linked to a tail shaft of the vehicle will precipitate a response parameter which may adjust the opening of gate assemblies which in turn adjusts the discharge of aggregate to maintain the design discharge rate for a particular job. The function of sensor is to detect the number of pulses determined by rotation of the tail shaft and relay this information to the PLC for appropriate adjustment of the gate assembly. According to one embodiment the sensor includes a cog on the tail shaft which reads pulses commensurate with the degree of travel of a vehicle wheel. The PLC, knowing the number of pulses can calculate the distance of travel of the wheel or horizontal speed and adjusts the gate assembly to either increase or decrease discharge of the material to be spread according to the design spread rate for a particular job. In an alternative embodiment, the PLC may make the gate assembly adjustments with reference to an alternative parameter such as wheel revolutions. The assembly may further comprise an incline meter to determine the angel of a truck body and an absolute linear displacement sensor which determines the precise position of the spread rate screeding assembly.
According to one embodiment there are nine individual gate assemblies, which are opened and closed by separate individual air actuated pneumatic rams. These may alternatively be hydraulically or electrically actuated. This enables an adjustment of the width of aggregate discharge opening. Gate arms may be forced open by pneumatic air and the aggregate in the hopper. The spread rate screeding rack controls the amount of gravel spread onto the road surface via an electric actuator. The range and degree of movement that the actuator controls forward or reverse movement is predetermined by the PLC. The computer receives it operating data from such parameters as road speed, angle of truck body, and an absolute linear displacement which determines the precise position of the spread rate. The PLC program will calculate from the input parameters the job discharge rate requirements and adjust the gate assembly accordingly, to ensure correct kg/m2 discharge or spread rate.
The present invention herein described according to a preferred embodiment has numerous advantages over the prior art Firstly, the computer control eliminates the human error which prevails in the prior art methods and apparatuses by allowing accurate control of the discharges of material by adjusting in the event of vehicle stoppages or slow down. The computer accurately controls the material spread rate in each and al operations and leaves the operator free to assume a monitoring role which includes watching for obstructions such as power lines. It is a mandatory requirement in road surfacing in which aggregate is spread from a hopper to employ an observer with a 5099 ticket whose mandate is to watch for power lines to ensure no snagging. This activity requires at least one individual but where a computer controlled assembly is employed in accordance with the invention, the operator of the assembly can also function safely as an observer due to the automation provided by the logic computer. The invention being adaptable as an attachment to a vehicle frees a tipper when not attached to the box spreader to be employed elsewhere. It also enables adaption to relatively small spreading jobs. For example jobs as small as 300 mm wide to 900 mm wide may be performed. The computer controlled apparatus can be used in spreading up and down hills or around corners and may be transported on public roads day or night. The spreader assembly may be switched from manual to automatic (computer driven) operation or from computer to manual operation.
It will be recognised by persons skilled in the art that numerous variations and modifications may be made to the invention as broadly described herein without departing from the overall spirit and scope of the invention. Examples of such variations include use of a single gate or plurality of gates to close the hopper opening, use of a hydraulic cylinder rather than an air actuated ram.
Number | Date | Country | Kind |
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PR 6220 | Jul 2001 | AU | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/AU02/00912 | 7/5/2002 | WO | 2/14/2005 |