AU697319B2

AU697319B2 - Scraping assembly for belt conveyors

Info

Publication number: AU697319B2
Application number: AU33191/95A
Authority: AU
Inventors: Robert Patrick Gilbert
Original assignee: Mato Australia Pty Ltd
Current assignee: Mato Australia Pty Ltd
Priority date: 1994-10-11
Filing date: 1995-10-11
Publication date: 1998-10-01
Anticipated expiration: 2015-10-11
Also published as: AU3319195A

Description

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AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

4i~ *4 It'I 556 Cll lit 4)1 Name of Applicant: Actual Inventor: Address of Service: MATO AUSTRALIA PTY LTD, A.C.N. 050 057 728 Robert Patrick GILBERT SHELSTON WATERS MARGARET STREET SYDNEY NSW 2000 Invention Title: SCRAPING ASSEMBLY FOR BELT CONVEYORS Details of Associated Provisional Application No. PM8725 dated 1 Itb October, 1994 The following stateme.t is a full description of this invention, including the best method of performing it known to us:i, r

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-2- The present invention relates generally to belt conveyors, and more particularly to a belt scraping apparatus for use with such conveyors.

Belt conveyors are used in a variety of applications for the transportation of particulate or granular material, such as coal, grain, ore, minerals, and the like.

One problem commonly encountered with belt conveyors is the tendency for particulate material to adhere to the surface of the belt. This problem is particularly significant in applications such as underground mining operations and coal transportation, where the mnaterial moving on the belt must continually be sprayed with water to suppress dust. The water mixes with the fine particulate component of the t~ coal or other material, and forms a slurry which is particularly prone to sticking to the r surface of the belt. This phenomenon reduces the transportation efficiency, and increases the running and maintenance costs of the conveyor.

In an attempt to ameliorate these problems, belt scraping devices have been developed to scrape residual debris from the surface of the belt. These are normally positioned near the underside of the conveyor, at or near the head pulley and just past 845115 the intended discharge point, such that the lower run of the belt on its return loop is substantially clean.

However, known scraping devices have several inher-nt disadvantages. The most significant of these relates to the need for the scrapers to accommodate surface irregularities in the belt. Such irregularities most commonly take the form of belt fasteners, which are typically formed from steel and protrude beyond the surface of the belt. These fasteners can cause hardened scraping blades to break, chip or shatter, f 1~1_ I~ I L ~JI p

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-3leading to reduced scraping efficiency and downtime whilst repair operations take place. This can also cause premature failure of the belt fasteners.

In an attempt to avoid these problems, some scraping blades have been formed from relatively soft materials such as polyurethane, polyplopylene and other plastics.

Whilst being better able to accommodate surface irregularities in the belt without breakage, such blades are prone to rapid abrasive wear, and hence require frequent replacement. This is costly, and again often results in undesirable downtime.

A further problem with known scraping devices relates to the need for each of several scraping blades to be individually adjusted to the correct position relative to 1, che belt, and relative to the adjacent blades. This set-up procedure is time consuming, labour intensive and expensive. Moreover, frequent recalibration is normally required in order to accommodate wear of the scraping blades.

It is an object of the present invention to provide a belt scraping assembly which overcomes or substantially ameliorates at least some of these disadvantages of 15 the prior art.

Accordingly, the invention as presently contemplated provides a scraping assembly for use with a belt conveyor, said scraping assembly comprising a first arm adapted to support a first scraping blade, and a second arm adapted to support a second scraping blade, said first and second arms being mounted to a support frame for rotation about respective first and second pivot axes, such that rotation of said arms about said pivot axes effects corresponding positional adjustments of the scraping blades with respect to the belt, the assembly further including actuating means h-' I C1 lid C

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connecting the first and second arms and being operable, in use, simultaneously to urge the scraping blades into scraping engagement with the conveyor belt.

Preferably, the first and second arms are supported for rotation about a common pivot axis in a scissor like configuration, the first and second scraping blades being disposed on opposite sides of the common pivot axis.

Preferably also, the support frame is rigidly mounted to a fixed frame member of the belt conveyor assembly, such that the pivot axis of the first and second arms is also substantially fixed.

The actuating means preferably includes resilient bias means disposed to accommodate a degree of resilient displacement of the first and second arms towards and away from the belt, thereby enabling the scraping blades to traverse surface irregularities in the belt.

In the preferred embodiment, the actuating means comprises an hydraulic or pneumatic cylinder extending effectively between the first and second arms, or 15 extensions thereof. The cylinder is preferably pressurised to urge the scraper blades into operative scraping engagement with the belt, with a predetermined degree of preload force to produce the desired contact pressure. Hydraulic damping is preferably also provided.

In the preferred embodiment, the assembly includes a pair of the first arms, and a pair of the second arms, the arms of each pair being disposed on opposite sides of the belt and connected to move in unison, for enhanced strength and stability. In this embodiment, a pair of actuating cylinders may be provided, each extending between a corresponding first and second arm on a respective side of the belt.

-~-IICIYII(- rl T I .4r The assembly is preferably positioned adjacent the head pulley of the conveyor, with the first scraper blade scraping a region of the belt disposed forwardly of the rotational axis of the head pulley, and the second scraper blade scraping a region of the belt disposed behind the rotational axis of the head pulley.

The points of engagement between each actuating cylinder and the respective first and second arms are preferably variable, to permit adjustment of the proportion of preload applied to the first and second scraping blades.

Unless the context clearly requires otherwise, throughout the description and the claims, the words 'comprise', 'comprising', and the like are to be construed in an inclusive as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to".

A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a diagrammatic side elevation showing a belt scraping assembly mounted to a belt conveyor according to the invention; and Figure 2 is a plan view showing the belt scraping assembly of Figure 1.

Referring firstly to Figure 1, the invention provides a scraping assembly 1 for use with a conveyor 2 comprising an endless flexible belt 3 extending between head pulleys 4. The head pulleys, intermediate rollers, drive mechanisms and associated support structures of conventional belt conveyor assemblies are well known to those skilled in the art, and so will not be described in further detail.

Initially describing one side of the apparatus only for ease of explanation, the 2 scraping assembly 1 comprises a first arm 10 incorporating a first blade holder 11, which 0 C c in turn supports a first scraping blade 12. A second arm 15 incorporates a pair of blade t t 25 holders 16, which similarly support respective scraping blades 17. Optionally, the blade holders 16 may be pivotably connected with the second arm in a free-floating o •configuration, to facilitate alignment with the belt. The first and second qt RA oI- Li CG:l CC

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a Cr rsCC C -6arms 10 and 15 are mounted with a support bracket 19 for rotation about a common transverse pivot axis 20. Each support bracket 19 is fixedly connected to a rigid frame member 21 of the conveyor such that the pivot axis 20 is essentially fixed.

As best seen in Figure 2, it will be appreciated that the assembly in practice includes a pair of first arms 10 and a pair of second arms 15, the arms of each pair being disposed on opposite sides of the belt. The first arms 10 are fixedly interconnected by intermediate connecting tube 23, whilst the second arms 15 are rigidly joined by connecting rod 24. Rod 24 extends coaxially through connecting tube 23, permitting independent relative rotation between the respective pairs of arms 10 and 15, with respect to the support brackets 19, about the common pivot axis It should be appreciated, however, that the interconnecting tube 23 and rod 24 can be omitted, to enable the independent movement of each pair of arms. In some applications, this may be desirable, to accommodate a greater degree of movement of the scraping blades so as to follow more closely the surface contours of the belt.

The assembly further includes actuating means in the form of a pneumatic cylinder 30 extending from a bracket 31 integral with the first arm 10, to the second arm 15, on each side of the conveyor. The lower end of each actuating cylinder 30 is releasably connected to a selected one of a linear array of apertures 32 formed in section 15a of the respective second arm. Similarly, the top end of each rneumatic cylinder is connected to a selected one of a linear array of apertures 33 formed in bracket 31 on the respective first arm.

Thus, it will be appreciated that the first and second arms are supported for rotation about a common pivot axis in a scissor-like configuration, with the pneumatic b 1 r )i ii ii r3i I t I .11 4t 3 Itt -7cylinder 30 extending between the first and second arms on each side of the conveyor.

It will also be noted that the single scraping blade 12 associated with the first arm and the dual scraping blades 17 associated with the second arm 15, are disposed on opposite sides of the pivot axis 21, as well as being disposed on opposite sides of the rotational axis 35 of the head pulley 4.

Turning now to describe the operation of the scraping assembly, the apparatu, is first secured in position beneath the conveyor belt adjacent the head pulley by means of support brackets 19, which are bolted to respective fixed frame members 21 associated with the conveyor. The pneumatic actuators 30 are then connected in position to extend between the respective first and second arms. This position is adjustable, by selecting different apertures from aperture arrays 32 and 33, to achieve the desired force distribution between the first and second arms. In some embodiments, the first and second arms 10 and 15 may be telescopically or otherwise adjustable in length, to provide a greater degree of adjustment over the force distribution, and the positioning, of the associated scraper blades. In this case, the arms are also adjusted to the required length at this stage. The hydraulic actuators are then connected to a supply of pressurised air.

Upon pressurisation, the actuators extend axially to urge the scraping blades associated with the first and second arms simultaneously into operative engagement with the belt. The degree of preload force is adjustable by regulating the supply pressure to achieve the desired contact pressure. Conversely, reducing the supply pressure beyond a predetermined minimum threshold allows the first and second arms B:i

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*r I a Ii ,ii I11 .4 Ia C simultaneously to fall away from the belt, to facilitate adjustment, replacement or repair of the scraping blades.

Because the pneumatic cylinders accommodate a degree of resilient displacement of the first and second arms, towards and away from the belt, this arrangement enables the scraper blades to traverse any surface irregularities in the belt, without damage or excessive wear. This is particularly beneficial in enabling the scraping blades to ride over belt fasteners. Otherwise, these fasteners, protruding from the surface of the belt, can damage the scraping blades or can themselves be damaged by the blades, leading to premature failure of the belt.

Moreover, the invention allows the individual scraping blades to be simultaneously retracted from the belt by simply reducing the pressure to the actuators, thereby permitting rapid replacement of warn or damaged blades. By simply repressurising the actuators, the blades are then simultaneously repositioned in a quick and efficient operation, without the need to stop the conveyor.

By adjusting the attachment points for the actuators, the force distribution between the different blades can be precisely adjusted to achieve optimum scraping efficiency, without the need for frequent separate adjustment of individual blades.

Furthermore, because the force applied to the blades by the actuators is dependent upon by the supply pressure, rather than the position of the arms, wear in the scraping blades is automatically compensated for without the need for any adjustment or recalibration. Additionally, the apparatus can readily be retro-fitted to existing conveyors, and can be adapted to suit a variety of scraping blades. In all these i r -9respects the invention represents a commercially significant improvement over the prior art.

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ii 'i j Although the invention as been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms. For example, one or more of the scraping blades may be replaced by rollers, pressure pads, or other means to maintain the scissor action of the arms, if not all scraping blades are required. Also, additional scraping blades may of course be fitted.

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Claims

2. A scraping assembly according to claim 1, wherein the first and second arms are supported for rotation about a common pivot axis in a scissor configuration, the first and second scraping blades being disposed on opposite sides of the pivot axis.
3. A scraping assembly according to claim 1 or claim 2, wherein the support frame is rigidly mounted to a fixed frame member of the belt conveyor, such that the pivot axes of the first and second arms are substantially fixed.
4. A scraping assembly according to any one of the preceding claims, wherein the actuating means includes resilient bias means disposed to accommnodate a degree of independent resilient displacement of the first and second arms, towards and away from the belt, thereby enabling the scraping blades to traverse surface irregularities in the belt. A scraping assembly according to claim 4, wherein the actuating means comprises an hydraulic or pneumatic cylinder extending effectively between the first and second arms, or extensions thereof. *1 fl~ I p -I A 1C~'r. I -11-
6. A scraping assembly according to claim 5, wherein said cylinder is pressurised to urge the scraper blades resiliently into operative scraping engagement with the belt, with a predetermined degree of pre-load force adapted to produce a desired contact pressure.
7. A scraping assembly according to claim 6, wherein the actuating means further includes an hydraulic damping mechanism.
8. A scraping assembly according to any one of the preceding claims, including a pair of said first arms, and a pair of said second arms, the arms of each respective r 'ieing disposed on opposite sides of the belt and connected to move in unison, tor ej ,triced strength and rigidity.
9. A scraping assembly according to claim 8, wherein said actuating means include a pair of actuators, each extending between a respective one of said first and said second arms on a corresi -)nding side of the belt. A scraping assembly according to any one of the preceding claims, wherein said assembly is adapted to be positioned adjacent a head pulley of the conveyor, with the first scraper blade scraping a region of the belt disposed forwardly of a rotational axis of the head pulley, and the second scraper blade scraping a region of the belt disposed behind the rotational axis of the head pulley. c*ttt 11. A scraping assembly according to any one of the preceding claims, wherein the points of engagement between the actuating mechanism and the respective first and 20 second arms are selectively variable, at least in discrete increments, to permit adjustment i of the proportion of preload applied to the first and second scraping blades. a t C J
12- 12. A scraping assembly according to claim 11, wherein a linear array of apertures is formed in each of the first and second arms, each ape-ture of each linear array being adapted for selective engagement by the actuating means.
13. A scraping assembly according to any one of the preceding claims, wherein the assembly is adapted for positioning on the underside of the belt, such that selective de- activation of said actuating means allows simultaneous retraction of the scraping blades from the belt under the influence of gravity, to facilitate blade replacement.
14. A scraping assembly according to any one of the preceding claims, wherein said first or said second arm is adapted to support multiple first or second scraping t10 blades. A scraping assembly substantially as hereinbefore described, with reference to the accompanying drawings. DATED this 10th Day of October, 1995 MATO AUSTRALIA PTY LTD Attorney: STUART M. SMITH Fellow Institute of Patent Attorneys of Australia of SHELSTON WATERS S I L ABSTRACT A scraping assembly for use with a belt conveyor. The scraping assembly comprises a first arm (10) adapted to support a first scraping blade and a second arm (15) adapted to support a second scraping blade The first and second arms (10,15) are mounted to a support frame (19) for rotation about respective first and second pivot axes such that rotation of the arms about the pivot axes effects corresponding positional adjustments of the scraping blades (12,17) with respect to the belt The assembly further includes actuating means connecting the first and second arms (10, 15) and being operable, in use, simultaneously to urge 10 the scraping blades (12,17) into scraping engagement with the conveyor belt erg, II C,,,t *f St I 44 r SI ''St Slt 4441, 8 4rr 145411 ~-i If- C i t