WO2006007645A1

WO2006007645A1 - Concrete extruder

Info

Publication number: WO2006007645A1
Application number: PCT/AU2005/001058
Authority: WO
Inventors: Graham Edward Hallett
Original assignee: Hallett, Jeanette, Erzsebet
Priority date: 2004-07-19
Filing date: 2005-07-19
Publication date: 2006-01-26
Also published as: MY136465A; CN101031688B; CN101031688A

Abstract

A concrete extruder (10) comprising a frame that houses a reciprocating ram (25), a ram driving means, a mould (22) and a hopper (16), wherein concrete mix is received in the hopper and compacted through the mould under the force of the reciprocating ram; the ram driving means being hydraulically operated and including a drive which drives a hydraulic pump (24) to pump fluid to a hydraulic cylinder (32) that is coupled to the ram for reciprocally driving the ram.

Description

CONCRETE EXTRUDER

The present invention relates to a concrete extruder for extruding strips of concrete, for example, in forming kerbs, footpaths, street guttering and the like.

Background to the Invention

Concrete extruding machines for laying strips of concrete on the ground are used to form road finishings such as sidewalks, gutters, median strips, drains, kerbs, etc. These machines generally comprise a chassis having a hopper for receiving a dry mix of ready mixed concrete that is poured into the hopper from a concrete truck. In general terms, kerb concrete mix is drier than concrete mix used in forming concrete slabs, foundations, etc. The hopper is located towards the middle of the machine so that the concrete mix extrudes through a mould box at the rear of the machine. The concrete mix is compacted as it is extruded and forms a finished strip of concrete that is shaped according to the shape dictated by the mould box.

A reciprocating ram driven by an engine powered reduction gearing system is located in the front of the extruder and moves reciprocally to compact the concrete mix against the mould box at the rear of the extruder. Furthermore, the force of the reciprocating ram against the concrete mix systematically moves the entire extruder machine in a forward direction. The machine is steered manually to move in a forward direction to follow a pre¬ set string line path.

Occasionally, the ready mixed concrete pouring into the hopper inadvertently contains foreign objects such as large aggregate, rocks, pieces of timber, steel and the like. This kind of foreign material can cause serious problems, particularly because concrete extruders operate with very close tolerances. On entering the extruder and falling between the ram and mould box, foreign objects can cause the ram to jam and suddenly stop. This can bend and possibly break the rods connected to the ram, bend crankshafts and even damage the gearbox beyond repair. Not only does this result in very expensive repairs and costly downtime but the unpredictable reaction of the extruder can potentially cause injury to machine operators.

A safer concrete extruder is required and particularly one that can cope with and safely compensate against the ingress of foreign objects.

Summary of the Invention

One embodiment of the present invention provides a concrete extruder comprising a frame that houses a reciprocating ram, a ram driving means, a mould and a hopper, wherein concrete mix is received in the hopper and compacted through the mould under the force of the reciprocating ram; the ram driving means being hydraulically operated and including a drive which drives a hydraulic pump to pump fluid to a hydraulic cylinder that is coupled to the ram for reciprocally driving the ram.

The ram preferably includes a swinging plate suspended from the frame. The swinging plate is suspended by two pairs of arms pivotally linked at opposite ends between the frame and the swinging plate.

The hydraulic cylinder is pivotally linked at a fixed end to the frame and at a driving end to the swinging plate. The hydraulic cylinder is preferably a pilot cylinder and includes a pressure relief valve. A control block is preferably provided between the hydraulic cylinder and hydraulic pump to control the direction and flow of fluid to and from the hydraulic cylinder. The control block preferably includes spool valves.

Brief Description of the Drawings

The present invention will now be described with reference to the figures of the accompanying drawings, which illustrate a particular preferred embodiment, wherein:

Figure 1 is a side sectional view of a concrete extruder according to an embodiment of the present invention;

Figure 2 is a cut-away perspective view of a front end of the concrete extruder;

Figure 3 is a perspective view of the rear end of the concrete extruder; and

Figures 4A to 4C illustrate three positions of the reciprocating ram assembly.

Detailed Description of Preferred Embodiment

The concrete extruder illustrated in the drawings is an improved machine over known extruders because it operates more efficiently and can more effectively deal with unexpected jams while still providing the full ramming force required to compact concrete mix when laying a strip of concrete.

This is achieved by introducing a hydraulic system, including a hydraulic drive means and a hydraulic cylinder, to drive the ram. The present system is capable of withstanding jolts and jams encountered by foreign objects entering the concrete mix.

As illustrated in Figure 1 the concrete extruder 10 has a front portion 11 defined by a front chassis 12 and a rear portion 13 defined by a rear chassis 14. A concrete mix hopper 16 is located between the front and rear portions 11, 13 and directs concrete mix down to a lower end 17 of the machine where the mix is compacted by a ram 25 just above the road surface.

The entire extruder moves forward as a result of the reaction force of the ram 25 ramming against the concrete at the lower end 17 of the hopper 16• Mounted at the front of the front chassis 12 is a pair of wheels 18 and height adjustment cylinders 20. Cylinders 20 are mounted at the front end of the chassis and each provide a mount for a wheel. This allows the height of the front and rear chassis 12, 14 to be adjusted relative to the wheels and ground, thereby adjusting the height of the concrete strip to be formed.

A steering rod 21 connected to the wheels is used to manually steer the extruder. The steering rod 21 is connected to one of the front wheels while the other wheel is attached to the steering rod by way of an assembly comprising a tie arm and two ball joints (not shown) such that both wheels turn with the steering rod 21. A spirit level (not shown) fitted across the front of the machine indicates cross levels to keep the machine level. Machine levelling is regulated by hydraulic height adjustment cylinders 20. A steel pointer (not shown) at the front of the machine is used to follow the string line path to correctly steer the machine in a forward direction. The front portion 11 (see Figure 2) of the concrete extruder 10 houses the power unit and hydraulic pump 24, ram 25 and other componentry required to provide a compacting force against concrete poured into hopper 16 from a concrete truck (not shown) . The rear portion 13 (see Figure 3) has an elongate mould 22 through which the compact concrete passes and forms a strip of concrete having a profile of the mould 22. Figure 3 also illustrates the walls of the hopper 16 held stable by struts 23.

Figures 1 and 2 illustrate the components contained in the front portion 11. A power unit and a hydraulic pump 24 are shown contained within a housing at an upper front end of the front chassis 12. The power unit used to drive the hydraulic pump in this embodiment is a 12 horse power drive engine. The hydraulic fluid used in the system is hydraulic oil.

Oil exits the hydraulic pump 24 from a hydraulic pump outlet 28 and flows through a hydraulic line 29 to an oil distribution control block 30. Control block 30 contains hydraulic spool valves (not shown) that control and alter the flow of oil through the control block 30. Two hydraulic lines 45, 46 communicate oil between the control block 30 and a hydraulic cylinder 32 that actuates ram 25. The hydraulic lines 45, 46 from control block 30 are connected one to each of the front end (hydraulic line 45) and rear end (hydraulic line 46) of the hydraulic cylinder 32. The hydraulic cylinder, which in this embodiment is a pilot actuated cylinder, is caused to extend and contract by introducing greater fluid pressure alternatively to the front and rear ends of the cylinder.

With the ram coupled to the hydraulic cylinder, the hydraulic system, comprising the hydraulic pump, control block, lines and hydraulic cylinder, control the ram to move reciprocally against the concrete mix in the hopper. The hydraulic cylinder 32 is a pilot hydraulic cylinder. A small pilot hole (not shown) in the cylinder is uncovered when the piston reaches the end of its stroke such that oil under pressure escapes out through the pilot hole and along the hydraulic line to the spool γalve where it activates the spool to shift and change oil flow direction. This pushes the ram back in the opposite direction. The ram is thereby moved reciprocally.

Other cylinder/spool valve combinations may be used to drive the ram, for example by way of a pressure sensitive spool valve or an electronic solenoid, however a pilot cylinder/spool valve combination is preferred because it avoids the build up of pressure required to change the direction of motion with the pressure sensitive spool valve and the unreliability of electrical components such as solenoids. A build up of pressure can be dangerous. The pilot cylinder operates in a simple and safe manner under only hydraulic control and does not require electrical signals or switches, which can be unreliable.

The hydraulic cylinder 32 is provided with a relief valve (not shown) which relieves the fluid pressure if the build up in the hydraulic cylinder 32 is excessive. This may occur where the ram encounters an obstruction which produces a sudden large force in the ram components and hydraulic cylinder. The hydraulic cylinder compensates for such a reaction by releasing pressure before the build up in pressure damages the control block, lines or pump. After removal of the obstruction the hydraulic pump returns the fluid pressure to normal and the relief valve, which is spring loaded, resets to close.

As shown in Figure 2 the hydraulic cylinder 32 is pivotally mounted to a bracket 34 that is attached to the internal front chassis 12. The movable stem 33 of hydraulic cylinder 32 is pivotally attached to the ram 25, which comprises a ram swinging plate 27, ram heads 26 and a ram front plate 36 mounted on the ram heads 26. Through its pivotal connection, the hydraulic cylinder can adjust its position relative to the chassis 12 and ram 25 to accommodate ram movement.

Bracket 35 to which the stem 33 of hydraulic cylinder 32 is pivotally attached is welded onto swinging plate 27.

The ram head 26 and ram plate 36 are both securely mounted on swinging plate 27 to swing therewith. The ram heads 26 are attached onto a rear end of the swinging plate 27.

Swinging plate 27 swings from two sets of parallel arms 38 that pivotally attach the swinging plate 27 to rigid cross members 40. Cross members 40 are stably mounted above swinging plate 27 between two inside walls of the front chassis 12. Parallel arms 38 are pinned at an upper end to cross members 40 at pivot points 42 and are pinned at a lower end to swinging plate 27 at pivot points 43.

Accordingly, as the hydraulic cylinder extends and retracts under changing fluid pressure from control block 30, swinging plate 27 moves to and fro in a slightly arcuate motion around pivot points 42 and 43. The swinging action of swinging plate 27 causes the ram head and ram plate 36 to repeatedly move in a ramming motion against and away from the concrete mix at the bottom of hopper 16, thereby compacting the concrete into mould 20.

Figures 4A to 4C illustrate a closer view of the swinging action of ram 25. Figure 4A illustrates the most retracted position of ram 25. Under hydraulic pressure delivered through front hydraulic line 45 to the front of the hydraulic cylinder 32, stem 33 is fully retracted into the cylinder 32. Ram swinging plate 27, suspended from pivot points 42 is pulled by cylinder 32 to the position illustrated in Figure 4A, which is a position furthest away from the concrete.

Figure 4B illustrates an intermediate position where the hydraulic cylinder is extended mid-way and the ram moves with momentum towards the left of the view of Figure 4B. Parallel arms 38 are vertical in this view.

Figure 4C illustrates the most extended position of the hydraulic cylinder at which point the ram plate (not shown in Figures 4A to 4C) applies its greatest force upon the concrete mix. In this figure, stem 33 of hydraulic cylinder 32 is fully extended by virtue of a greater hydraulic pressure being supplied by the rear hydraulic line 46 to the rear of cylinder 32 and behind stem 33. In Figure 4C parallel arms 38 have swung to an inclination angle opposite to that of Figure 4A. After impact, the oil pressure in the hydraulic cylinder 32 is reversed to withdraw ram 25 back through the position illustrated in Figure 4B to resume the fully retracted position illustrated in Figure 4A.

The double acting hydraulic cylinder with pressure controlled at both the front and rear ends allows the ram to operate at high speeds and generates a very good concrete compacting force. The relief valve on hydraulic cylinder 32 operates when the cylinder is subjected to an unexpected and/or an excessive force to release pressure before damage occurs to the extruder rather than causing damage by back pressure to the ram, the hydraulic cylinder and all other driving components. Immediately at the encounter of an obstruction, the two way action of the hydraulic cylinder allows the oil pressure in the ram to be reversed to stop the ram. The obstruction can then be safely removed to allow work to continue. An advantage of the hydraulically powered concrete extruder is that the hydraulic ramming components can be stopped immediately in an emergency situation. Shutdown is much slower in mechanically powered extruders where it takes several seconds before the mechanical components come to a standstill. Emergency stop buttons may be provided at one or more points on the extruder where operators are likely to stand during operation. When activated, the emergency stop buttons bring the ram immediately to a standstill without the mechanical delay experienced by existing extruders.

Fluid flow in the hydraulic system can be instantaneously varied and redirected. This allows for the advantage of infinitely adjusting the speed and swing of the ram, which may be desirable in confined areas.

Furthermore, replacing the known reduced gearing and crank system with the present hydraulic system significantly reduces the minimum size of the front portion of the machine. The present system does away with long rods and cranks and is on the whole more compact. Accordingly, this allows the concrete extruder to operate in tighter areas and with a smaller turning circle.

Under hydraulic control, the extruder can be set at any desired speed setting. This allows for more accurate work to be carried out in tight and confined spaces.

It will be understood to persons skilled in the art of the invention that many modifications may be made without departing from the spirit and scope of the invention.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A concrete extruder comprising a frame that houses a reciprocating ram, a ram driving means, a mould and a hopper, wherein concrete mix is received in the hopper and compacted through the mould under the force of the reciprocating ram; the ram driving means being hydraulically operated and including a drive which drives a hydraulic pump to pump fluid to a hydraulic cylinder that is coupled to the ram for reciprocally driving the ram.

2. The concrete extruder claimed in claim 1, wherein the hydraulic cylinder is pivotally linked at a fixed end to the frame and the driving end to the ram.

3. The concrete extruder claimed in claim 2, wherein the hydraulic cylinder is a pilot cylinder having hydraulic lines communicating with a forward end and a rear end of the cylinder.

4. The concrete extruder claimed in claim 3, wherein the hydraulic cylinder comprises a pressure relief valve.

5. The concrete extruder claimed in any one of the preceding claims, wherein the ram includes a swinging plate suspended from the frame.

6. The concrete extruder claimed in claim 5, wherein the swinging plate is suspended by two pairs of arms pivotally linked at opposite ends between the frame and the swinging plate.

7. The concrete extruder claimed in any one of the preceding claims, wherein a control block is provided between the hydraulic cylinder and hydraulic pump to control the direction and flow of fluid to and from the hydraulic cylinder.

8. The concrete extruder claimed in claim 7, wherein the control block includes spool valves.

9. The concrete extruder claimed in any one of the preceding claims, wherein the drive is a twelve horse power drive engine.

10. The concrete extruder claimed in any one of the preceding claims, wherein a pair of wheels is provided at the front of the frame.

11. The concrete extruder claimed in claim 10, wherein the wheels are mounted on height adjustable cylinders for adjusting the height of the frame relative to the ground.

12. The concrete extruder claimed in any one of the preceding claims, wherein an emergency stop is provided on the exterior of the concrete extruder to manually enable operation of the extruder to be stopped.

13. A method of extruding a strip of concrete comprising: supplying a hopper in a concrete extruder with concrete mix; and compacting the concrete mix through a mould in the concrete extruder to produce a strip of concrete by hydraulically driving a reciprocating ram against the concrete mix and forcing the concrete mix through the mould, whereby the ram is driven by a hydraulic pump that pumps fluid to a hydraulic cylinder that is coupled to the ram.

14. The method claimed in claim 13, wherein the hydraulic cylinder is a pilot cylinder whereby fluid is alternatively supplied and removed from a forward end and from a rear end of the cylinder by way of hydraulic lines.

15. The method claimed in claim 13 or 14, including driving the hydraulic pump by way of an engine.

16. The method claimed in any one of claims 13 to 15, whereby excessive pressure in the hydraulic cylinder as a result of a large force on the ram is released through a relief valve in the hydraulic cylinder.

17. The method claimed in any one of claims 13 to 16, include changing fluid pressure in the hydraulic cylinder by way of a control block hydraulically connected between the hydraulic cylinder and the hydraulic pump.

18. The method claimed in any one of claims 13 to 17, including immediately stopping motion of the reciprocating ram by way of a manually operated emergency stop provided on the exterior of the concrete extruder.