[0001] The present invention relates to the field of dispensing and delivering large volumes of fiowabie material to a desired location.

£0002] In one form, the invention relates to chutes for guiding slurries, particularly industrial slurries such as concrete from a concrete mixer to a locus.

[0003] it will be convenient to hereinafter describe the invention in relation to concrete slurries, however it should be appreciated that the present invention is not limited to that use only and can be used, for example, fo other fiowabie materia!.

BACKGROUND ART

[0004] It is to be appreciated that any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the present invention. Further, the discussion throughout this specification comes about due to the realisation of the inventor and/or the identification of certain related ait problems by the inventor. Moreover, any discussion of material such as documents, devices, acts or knowledge in this specification is included to explain the context of the invention in terms of the inventor's knowledge and experience and, accordingly, any such discussion should not be taken as an admission that any of the material forms part of the prior art base or the common general knowledge in the relevant art in Australia, or elsewhere, on or before the priority date of the disclosure and claims herein .

[0005] Concrete for construction sites is typically mixed in a rotating drum of a concrete mixing truck and the freshly mixed concrete is guided into a molding structure such as a set of forms. Concrete mixing trucks are typically charged with the dry components of concrete (cement and aggregate such as sand and gravel) and water with mixing occurring during transport, or they are charged with pre-mixed concrete. The concrete is maintained in a semi-liquid state by rotation of the drum until delivery. A spiral blade within the drum is rotated in one direction to push the concrete deeper into

Substitute Sheet

(Rule 26) RG/AU the drum, and in the opposite direction to discharge, or force the concrete out of the drum.

[0006] Typically, during discharge the concrete is forced from the drum into a collector, then into a chute system. The chutes system typically includes a pivotable main discharge chute, a second fold-out chute and optionally, one or more extension chutes. The chute system is typically manually assembled, disassembled and positioned prior to discharge and disassembled after discharge.

[0007] Freshly mixed concrete is very dense and dispensed from the drum in relatively large volumes, it is also quite abrasive and chemically corrosive. Accordingly the chute is subjected to significant physical stresses and chemical stress.

[0008] In view of these characteristics of concrete, the past, chutes have been manufactured of thick gauge sheet metal. As a result chutes have been very heavy, and difficult to assemble, disassembly and reposition. This reduces work efficiency and increases the likelihood of issues arising in reiation to occupational health and safety of workers.

[0009] Metal is also vulnerable to corrosion by chemical reaction such as oxidation. Over time, abrasive wear and chemical corrosion roughens the inner, guide surface of the chute, preventing smooth flow of the concrete and making it difficult and time consuming to clean. Ultimately they require ongoing maintenance or replacement due to corrosion,

[0010] Accordingly, in the past efforts have been made to overcome these problems. For example US patents 5,184,706 and 5,056,641 relate to a chute assembly having sections comprising fibreglass reinforced polyurethane structural framework, and a polyurethane liner. The structural frame may include any combination of central, side or diagonal ribs. The chute sections can form linkages comprising a hook member that can be received within a complementary shaped recess in a cammed socket housing, and a rounded projection that is received in a socket. However there is often damage and warping at the ends of such chute sections where they abut due to the significant physical stresses on the chute. [0011] international patent application WO 2009006667 and Australian design registrations AU 316178 and AU 317430 in the name of Dahlsher are directed to a chute comprising a frame joined together with a liner, both constructed of a polymeric material such as polyurethane. The frame may include lateral, diagonal or longitudinal stiffening ribs in specific conformations, The invention is directed to overcoming the disadvantages of having separate polymeric liners, and to reduce the weight of chute sections (p.2), However in use, this type of chute is prone to buckling, twisting and failing under load, and tend to open up and fiatten out when filled with a heavy load of wet concrete.

[0012] US patent 7,578,379 relates to a multi-section chute, each section comprising a non-metallic, preferably polymeric, arcuate chute and longitudinal channel shapes integral with the longitudinal edges, plus a re-enforcing rib to resist longitudinal bending. Additional reinforcing material may be used in the ribs and fastening assembly (col.4, lines 62-65). The sections are linked by a fastening assembly comprising a dual hook and pocket pin arrangement that has positive, gravity locking. The polymeric chute may include a top layer colour coded to indicate wear (col.5, lines 47-55). Each section is typically from about 2 feet to 4 feet in length and can be nested for storage. However the sections are relatively heavy, particularly when concrete adheres and builds up on them they can be a source of repetitive strain injuries and other occupational health issues for workers who must repeatedly lift and shift them.

[0013] US patent application 2003/226737 and patent 6,367,606 relate to a chute having a pair of rail tubes along each side, which can hold a liner in place. The chute is preferably aluminium. The skin of the chute can be an engineered plastic such as polyethylene. Link members are attached to front and rear flanges of the chute and comprise a hook and hook mount respectively. However this type of design is prone to separation of the liner and tubes.

[0014] Other prior art chutes such as those described in US patent application 2004154898 are constructed with replaceable liners. Specifically they include extruded sections which fit together and can slidably receive a liner that is slid into position from one end of the chute. A stiff ener may be used to stabilise the chute. [0015] US patent application 4,054,194 relates to chute having a metal frame comprising longitudinal frame members and at least two arcuate cross members at either end defining a curved trough, plus a replaceable polyurethane liner. Links between chute sections are formed by pintles and fittings on a first section which interlock with complementary fittings on a second section. However, the ongoing need to insert, remove and dispose of replacement liners is expensive in terms of inventory, and man- hours,

SUMMARY OF INVENTION

[0016] An object of the present invention is to provide a chute that is suitably light for manual handling, yet can support significant loads and resist physical stresses.

[0017] A further object of the present invention is to alleviate at least one disadvantage associated with the related art.

[0018] It is an object of the embodiments described herein to overcome or alleviate at least one of the above noted drawbacks of related art systems or to at ieast provide a useful alternative to related art systems.

[0019] A chute for delivery of material to a locus comprising an elongate chute body of poSyurethane-based polymer having a curved cross sectional profile, the chute body being of predetermined thickness for encapsuiating load bearing members adapted to reinforce the chute body to resist bending and twisting forces, wherein the polyurethane- based polymer has any one or any combination of the following characteristics: i. a hardness of between at Ieast 95 Shore A and 85 Shore D; ii. tensile strength of between about 32 and 55 !VJPa, (ASTMD412-61T); iii. elongation at break of less than 200% (AS1683.11 ); iv. tear strength of betweeni 90 and 300 kN/m (ASTM D470); and v. specific gravity of between 1.07 and 1.25.

[0020] Typically the chute is of the type adapted for guiding slurries such as concrete from the discharge end of a concrete mixer truck to a locus. The chute may be suitable for use as a main discharge chute, a foid-out chute or an extension chute. Two or more chutes according to the present invention can be connected to form a longer chute or section of a chute system.

[0021] The chute body of the present invention is typically less than 810 mm in length, more typically 800 to 810mm in length for use with concrete mixing trucks. This compares with a length of about 940mm for chute bodies of the prior art. It will be appreciated that the dimensions of the chute of the present invention can be adapted as required for a particular application. For example, the length of the chute can be reduced for use on small trucks such as those known as 'mini-mix' trucks. Alternatively, or in addition, different length chutes according to the present invention can be connected together. If may be useful to connect a number of chutes of similar length, terminating with a comparatively short chute.

[0022] The cross sectional profile is curved, defined by a concave inner guide surface and a convex outer surface. Any convenient degree of curvature may be used.

[0023] The construction of the chute according to the present invention is also considerably lighter, typically 9 to 11kg, compared with over 10 to 18kg for chutes of the prior art.

[0024] The load bearing members are designed to support a load, while distributing and minimising the twisting, compression and bending forces applied to the chute when it is in operation. The load bearing members also help to hold the chute body in its moulded shape.

[0025] Preferably the load bearing members include a first U-shaped member located at a first end of the chute, a second U-shaped member located at the second end of the chute. In a particularly preferred embodiment, the load bearing members form a skeleton with at least two, preferably at least three ribs. The ribs may be integral with the U-shaped members. Typically the ribs are parallel to each other and approximately perpendicular to the end members. During molding of the chute body, the ribs may facilitate release of air from the mould.

[0026] Thus in a second aspect of embodiments described, the load bearing members form a skeleton of the chute of the present invention which further comprises: a first U-shaped member located at a first end of the chute body, a second U-shaped member located at a second end of the chute body, at least two, preferably at least three ribs integral with the first and second U- shaped members, and at least two chute connection means located adjacent one or both ends of the chute and integral with the load bearing skeleton.

[0027] The chute connection means may include hook members or two loop members. Preferably two hook members are integra! with the first end of the chute body, and two loop members are integral with the second end of the chute body. Two or more chutes can thus be linked together by attaching the hook and loop of adjacent chute ends.

[0028] The hook and loop may be principally formed by the polymer, or the polymer in combination with the frame. For example, typically the first U-shaped member includes two integral hooks enclosed in the polymer. Typically the second U-shaped member includes two integral pins enclosed in the polymer plus a polymer web to complete the loop. Alternately the load bearing members may include an integral loop enclosed by the polymer.

[0029] in a particularly preferred embodiment the first U-shaped member includes hooks formed by laser cutting a flat section, enclosed in polymer. [0030] Typically the ioad bearing members are stee! rods, such as 10 - 14 mm, preferably 12 mm steel rod. The load bearing members are encapsulated within the polymer body by mechanical fixation and/or chemical bonding.

[0031] The polymer preferably has high abrasion resistance, good impact qualities and is water resistant. The polymer may be hot castabie, but is more preferably cold castab!e. The thickness of the casing can be adjusted to suit the application.

[0032] This is particularly important when the chute is used for transport of concrete slurry. The polymer optimally resists the buiid up of concrete on the body of the chute. This avoids the weight increasing rapidly due to accumulation of concrete and makes the chute easier to clean.

[0033] Many polymers, particularly polyurethane based polymers such as those described in US patent 4,716,210 are known and used as wear-resistant coatings for metal and other surfaces, not all are suitable for the present invention. In particular not ail solid polyurethane elastomers are suitable for casting to form chutes according to the present invention. For example, chemical resistance, the ability to successfully cast the polymer in a mould and other physical: characteristics are very type dependent,

[0034] A typical polyurethane-based polymer suitable for use in the present invention would have the following characteristics:

» a hardness of between at least 95 Shore A, and 85 Shore D:

* tensile strength of between about 32 and 55 MPa, (ASTMD412-61T); » elongation at break of less than 200% (AS1683.11 };

♦ tear strength of between 190 and 300 kN/m (ASTM D470);

• specific gravity of between 1.07 and 1.25. [0035] Typically the polymer is either a PPG (polypropylene glycol) or PTMEG (poiytetramethyiene ether glycol) based polymer. For example, preferably the polymer is chosen from the PPG or PTMEG families of polymers which exhibit excellent load bearing and high abrasion resistance. Pre-polymers with these backbones are known as tough elastomers which have previously been used in a host of applications including wheels, rollers, grain handling equipment, squeegees and gears.

[0036] In another aspect of embodiments described herein there is provided a method for moulding a chute accordtng to the present invention, the method comprising the steps of:

(a) pre-heating an appropriately shaped mould containing the load bearing members,

(b) at least partially degassing a polyurethane prepolymer and curative and combining same to form a mixture,

(c) stirring the mixture,

(d) vibrating the mixture to further at least partially degas the mixture,

(e) pouring the mixture into mould, and

(f) allowing the mixture to form a cured polyurethane based polymer.

[0037] Preferably the polyurethane based polymer is chosen from the group comprising MDI-PPG polymers and TDl-PTMEG polymers and the prepolymer is chosen from PPG and PTMEG, while the curative is chosen from a methylene diphenyl diisocyanate (MDI) or a toluene diisocyanate (TP!) or a dt-(methylthio)toluenediamine (DivlTA) as appropriate. The curative Ethacure 300 LC or Eracure 110 is particularly useful for the method of the present invention.

[0038] The chute according to the present invention may be used for example, as a main discharge chute, a fold-out chute or an extension chute to form a discharge system for material such as concrete slurry, directing its fiow from the revolving drum of a concrete mixing truck to a locus such as a form for setting concrete.

[0039] In another aspect of embodiments described herein there is provided a method for delivering concrete slurry to a locus including the steps of attaching one or more chutes according to the present invention to a concrete mixing truck and discharging concrete from a revolving drum of the mixing truck to the one or more chutes.

[0040] In yet a further aspect of embodiments described herein there is provided a system for delivering concrete slurry to a locus, the system comprising main discharge chute, a fold-out chute or an extension chute according to the present invention.

[0041] Other aspects and preferred forms are disclosed in the specification and/or defined in the appended claims, forming a part of the description of the invention.

[0042] In essence, embodiments of the present invention stem from the realization that a ioad bearing members can be combined with a body made of a specific polymer to work together enables absorption of the twisting, bending and compressive stresses applied, the polymer additionally being suitable for use with abrasive materials. The tensile and elongation properties of the polymer together with the conformation of the load bearing members give the chute its shape, stability, integrity and durability, while increasing its ability to be manually handled.

[0043] Advantages provided by the present invention comprise the following:

• shorter length and lighter weight compared with prior art chutes, reducing occupational health and safety handling issues,

• reduced concrete adherence and build up, readily cleaned down with water,

• resistance to degradation by chemical reaction, ♦ reduced maintenance and increased useful lifespan,

♦ compatibly with conventional, industry accepted fixing systems and thus interchangeable with existing chute designs,

* discharge edge does not wear to a feather edge; no cutting edges,

• easier to assemble and disassemble,

« no assembly required; conventional chutes require outer steel frame and liner to be assembled prior to use.

• resists chute failure due to buckling, twisting and opening under load, and

• resists deformation and warping at the abutting ends of linked chutes.,

[0044] Further scope of applicability of embodiments of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosure herein will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Further disclosure, objects, advantages and aspects of preferred and other embodiments of the present application may be better understood by those skilled in the relevant art by reference to the following description of embodiments taken in conjunction with the accompanying drawings, which are given by way of illustration only, and thus are not limitative of the disclosure herein, and in which:

* Figure 1 illustrates in perspective view, load bearing members of a chute according to the present invention; ♦ Figure 2 illustrates in perspective view, a chute according to the present invention comprising the load bearing members of Figure 1 enclosed within a poiymer chute body; and

• Figure 3 illustrates a cross sectional view of the chute of Fig.2 across AA' of Fig.2.

DETAILED DESCRIPTION

[0046] Preferably the chute as depicted in Figure 2 is a unitary moulding of durable, rigid, high abrasion resistant polyurethane (1 ) such as a tough elastomeric po!yurethane polymer chosen from the PPG or PTMEG family of polymers. The polymer fully encloses a steel load bearing members forming a skeleton (15) as depicted in Fig.1. In this embodiment the steel load bearing skeleton (15) is fui!y welded, fabricated from mild steel, such as 12 mm mild steei rod. Preferably the chute has a length of about 800 mm, and a weight of about 11 kg or less which is significantly less length and weight than chutes of the prior art.

[0047] In this embodiment the chute includes hooks (3a,3b) which comprise metal hooks (9a,9b) integral with a first end of the toad bearing skeleton (11 ), which are encased by polymer (3a, 3b). At the other end of the load bearing skeleton (11) are pins (7a,7b) which are encased in polymer and provide reinforcement for loops which include polymer outrigger webs (6a,6b).

[0048] The hooks (3a,3b) of one chute can be linked to corresponding loops (5a,5b) of an adjacent chute. Thus individual chutes can thus be linked together to form a system of chutes for transfer concrete or similar slurry material over a desired distance. The chute body formed of poiymer includes features such as a web (4a, 4b) which in combination with the metal hook (9a,9b) supports the chute (1 ) and resists the twisting and tension forces applied at the hooks (3a,3b) when the chute (1 ) is under load.

[0049] At either end of the chute (1 ) are U-shaped steel reinforcing rods (11,12) enclosed in polyurethane (14) which resist opening up of the chute under load. These U- shaped end members (11 ,12) resist the twisting and opening forces applied to the chute (1) when a load is applied. The longitudinal top edges of the chute (1 ) are defined by ribs (8a ,8b). An additional compression member (2) comprising a longitudinal rib (10) enclosed in poiymer is located intermediate the other two ribs {8a, 8b). The ribs (8a,8b _} 2) resist bending and buckling and of the chute and add stiffness to resist twisting.

Experimental

[0050] A number of attempts were made to optimise the present invention and this identified a number of polymers, including polyurethane polymers which were not suitable. For example, in one attempt, a fiberglass prototype mould of a chute body was made to length of 840mm and the mould was heated to temperatures between 65 and 80°C. A variety of materials from the following suppliers of polyurethane were used in trial mouldings of the body, including products from Chemtura (Adiprene® LF753D a polyurethane elastomer known for its abrasion resistance and strength), Rebain (Zthane™ a two component polyoi/MDI isocyanate polyurethane) and Era Polymers (ETL69D, ETX76D, Eracast 76D, Eracast 72D, ETX80D, EHP95A and ETL100AS - a range of castab!e polyurethanes).

[0051] The trial mouldings revealed that a significant number of polymers were not suitable. In particular, some failed because it was not possible to vent the moving pockets of air that were caught in the sides or top of the mould during the pouring of the polymers. Furthermore several of the chosen polymers, such as Eracast and EXT80D were too brittle and shattered during the moulding trials.

[0052] For example, the polymer from Chemtura was machine poured into the mould. The trial failed because it was not possible to eliminate air bubbles from the polymer.

[0053] MDi -PPG polymer P20 (Zthane®) was successfully hand cast into a mould. The mould was heated to 25°. The prepolymer and curative were degassed for 1 minute and mixed together at room temp (10 to 15 °C) for 1 minute. This is crucial to extend the potlife of the material which enables the material to fill up the mould before commencing the curing reaction. The mould was placed on a vibration table which was vibrated with an air pressure of 2 to 3 psi. The combination of the extended potlife of the material and the vibration of the mould eliminated entrapment of the moving pockets of air thus resulting in a successful casting. The product was demoulded after 1 hour. Full curing typically takes place after 24 hours at room temperature.

[0054] A TDI -PTMEG polymer L-EXT77D was been successfully machine poured and hand poured into a mould. The polymer was heated to 70°C and the curative remained at room temperature. The mould was heated to 70°C . Both the curative and polymer were degassed until the air was removed. Again the mouid was placed on a vibration table which was vibrated using an air pressure of 2-3 psL The mould was placed in an oven for 16 hours to allow the product to be cured.

[0055] While this invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modification{s). This application is intended to cover any variations uses or adaptations of the invention following in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth.

[0056] As the present invention may be embodied in several forms without departing from the spirit of the essential characteristics of the invention, it should be understood that the above described embodiments are not to limit the present invention unless otherwise specified, but rather should be construed broadly within the spirit and scope of the invention as defined in the appended claims. The described embodiments are to be considered in all respects as illustrative only and not restrictive.

[0057] Various modifications and equivalent arrangements are intended to be included within the spirit and scope of the invention and appended claims. Therefore, the specific embodiments are to be understood to be illustrative of the many ways in which the principles of the present invention may be practiced. In the following claims, means-plus-function clauses are intended to cover structures as performing the defined function and not only structural equivalents, but also equivalent structures.

[0058] "Comprises/comprising" and Includes/including" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preciude the presence or addition of one or more other features, integers, steps, components or groups thereof. Thus, unless the context clearly requires otherwise, throughout the description and the claims, the words 'comprise', 'comprising', Includes', including' and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to".