Screen securing device

A securing device for securing a screening panel to a support frame of a vibrating screen assembly. The securing device has a body with a securing means at one end and a stub at the lower end. The securing means is shaped to mate with a complementary securing cavity in the screening panel and has a hole that receives a pin located in the securing cavity. The stub may be threaded to engage the support frame.

FIELD OF THE INVENTION

This invention relates to a securing device for holding panels onto a vibrating screen. In particular, it relates to securing resiliently deformable panels suitable for use in a vibrating screen for separating particulate matter, particularly mineral ores.

BACKGROUND TO THE INVENTION

The use of vibrating screens for separating mineral ores is well known. Vibrating screens are used in three related applications: classification; dewatering; and media recovery. Classification is a process of separating feed material into two or more controlled size ranges. Dewatering separates water from the feed material and typically requires a much finer screen than classification. Media recovery is similar to dewatering as the screen is used to recover fluid from the feed material.

In our co-pending international application number PCT/AU2008/000698 titled VIBRATING SCREEN PANEL there is described a novel screen panel that has cross-flow and in-flow slots. In use, the screen panel is secured to a vibrating screen deck. It is preferable for the screen panel to be reversibly secured to the screen deck so that the screen panel can be easily removed and replaced. The screen deck wears out much quicker than any other components of the vibratory machine.

There are various known devices for attaching the screen panels to an underlying support frame. In one prior art system described in U.S. Pat. No. 4,871,288 the screen panels are held in place by elongate securing devices that screw into an underlying sub-frame structure. Each securing device has a head that engages a socket formed by complementary cavities in adjacent screen panels.

Another known arrangement is described in U.S. Pat. No. 6,957,741. Each securing device has a locating protrusion and a securing protrusion that engages a complementary locating recess and securing recess on an overlying screen panel. The combination of the locating protrusions/recesses and securing protrusions/recesses act to hold the screen panel in place on the underlying frame.

Each of the known arrangements have proven to be useful but the performance can be improved.

OBJECTS OF THE INVENTION

It is an object of the present invention to provide a device with improved performance compared to the known prior art, or at least to offer the public a useful alternative.

SUMMARY OF THE INVENTION

In one form, although it need not be the only or indeed the broadest form, the invention resides in a securing device for holding a screening panel to a support frame of a vibrating screen assembly, the securing device comprising:

a body;

a securing means at an upper part of the body for mating with a complementary securing cavity on the screening panel;

a hole formed in the upper part of the body adjacent the securing means for receiving a pin of the screening panel; and

a stub at a lower part of the body for engaging a corresponding socket in the support frame.

Preferably the securing device further comprises a flange intermediate the upper end of the body and the lower end of the body.

The securing means may suitably comprise a ridge.

Preferably, the securing means comprises a tapered neck and an enlarged head at the narrower end of the neck. The head may suitably include a circumferential ridge.

Preferably the hole extends through the body from the upper part to the lower part.

In one aspect of the invention the stub is formed as a blank in which a thread is cut by the action of screwing the securing device into the socket in the frame.

Optionally, the flange is suitably shaped at an outer perimeter to be engaged for tightening, preferably by a tool.

In another form the invention resides in a screening panel for a vibratory screen assembly comprising:

a screen deck with multiple screening apertures;

a perimeter enclosing the screen deck;

at least one securing cavity formed in the perimeter, each securing cavity having a shape adapted to receive a securing means; and

a pin extending from the perimeter into the cavity for engaging a corresponding hole in the securing means.

Preferably, the securing cavity has a shape adapted to receive securing means in the form of a tapered neck having an enlarged head at a narrower end of the neck.

DETAILED DESCRIPTION OF THE INVENTION

In this specification, adjectives such as first and second, left and right, and the like may be used solely to distinguish one element or action from another element or action without necessarily requiring or implying any actual such relationship or order. Words such as “comprises” or “includes” are intended to define a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed, including elements that are inherent to such a process, method, article, or apparatus.

Referring toFIG. 1there is a shown a perspective view of one embodiment of a securing device10. The securing device10is formed from plastics material but in other embodiments may be formed from aluminium or other metals. The securing device10consists of a body11having a securing means12at an upper end13. In the embodiment ofFIG. 1the securing means12consists of a ridge121near the top of the body11that defines a neck122below.

A hole14is formed in the upper end13. The hole extends into the body10for sufficient distance to receive a pin on a screening panel, as described below. In some embodiments the hole14extends through the length of the body10, as shown inFIG. 8.

At a lower end15of the body11is a stub16. As will be described below, the stub engages a corresponding socket on a support frame of a vibrating screen assembly.

A flange may be formed intermediate the upper end13and the lower end15. In the preferred embodiment the flange is shaped to be engaged by a tightening tool to assist with engaging the securing device10into the corresponding socket. The flange may be round for tightening by hand but it is more suitably shaped, such as hexagonal shape, so it can be engaged by a wrench or a socket. Although the flange is shown as pronounced inFIG. 1it may be more subtle, as shown inFIG. 9. In some embodiments there may not be a requirement for a flange.

Referring toFIG. 3, there is shown a sectional side view of the securing device ofFIG. 1holding adjacent screening panels20. Each screen panel20has a securing cavity21shaped to receive the securing means12(as seen most clearly inFIG. 4). The securing cavity21has a half round shape centred on a pin22. The pin22also has a half round shape such that abutting screening panels form a circular cavity with a central circular pin. The circular pin is sized and shaped to fit within the hole14in the upper end13of the securing device10.

The circular cavity formed by the abutting securing cavities21serves to locate the screen panels20on the securing device10and the circular pin formed by the abutting pins22locates within the cavity14. The combination of the pin and the cavity serves to firmly but removably hold the screen panels20on the securing device10.

It will be appreciated that the securing means12, securing cavity21, hole14and pin22are not limited to the shapes shown in the preferred embodiment. The securing cavity21may have any shape that corresponds to the shape of the securing means12. The shape of the securing means may be, for example, square or hexagonal. Similarly the hole may be square or hexagonal. For ease of manufacture a circular shape is preferred.

The structure of a screen panel20is seen most clearly inFIG. 4. Each screen panel20is formed from plastics material, most commonly polyurethane. The screen deck23includes multiple screening apertures such as24. The screen panel20has a perimeter25that is thicker than the screen deck23. The security cavity21and pin22are formed in the perimeter25at the time of moulding the screen panel.

The securing device10may be connected directly to a frame30or via an adapter31, as shown inFIG. 5. There are various types of screening machines in the market and each has a different arrangement for holding screen panels. In one method of assembly the securing device10is screwed directly in the frame30, as shown inFIG. 6and discussed later. However the dimensions of the securing device10may not match the dimensions of a hole32in the frame30and an adapter31will be needed.

The invention is not limited to any particular screening machine or frame design. By way of example, an adapter31may include a threaded section33that is designed to match with a thread in the hole32in the frame30. Alternatively there may not be a thread and the adapter31may be welded or glued into the hole32. In another embodiment the adapter31may be forced into the hole32and be held by an interference fit. Other attachment techniques will be known to persons skilled in the art.

If an adapter31is used it is preferable that the securing device10is screwed into the adapter31so it can be removed. In one preferred embodiment a thread is cut into the stub16by the action of screwing the securing device10into a threaded hole34in the adapter31. The thread in the threaded hole34is suitably hardened and the stub16is suitably softer so that a thread is cut in much the same way as a die is used to cut a thread on a bolt.

It has been found that D series polymers, such as polyester, polypropylene and polyphenylene sulphide are suitable materials due to their mechanical properties.

If the dimension of the hole32in the frame30matches the dimension of the stub16, the same self-cutting approach can be used to screw the securing device10directly into the frame.

It will be appreciated that a thread161can be pre-cut into the stub16as shown inFIG. 6. The securing device10may be screwed into the adapter31or the frame30. Leaving the stub16without a thread facilitates a broader range of possible fixing options.

To facilitate assembly the securing device10includes a flange17. In the preferred embodiment the flange17is hexagonal like a conventional hex head bolt. The securing device10can be tightened into the hole32with a wrench, although it is more convenient to use a socket and air gun or electric drill. If the securing device is pre-threaded it could be tightened by hand, in which case the flange may be a knurled disc or similar. It will be appreciated that the flange may be any of a broad range of possible structures.

Assembly of screen panels20to a frame30is shown inFIG. 7. Securing devices10are screwed into threaded holes32in the frame30. Securing devices10in the middle beam35of the frame30are of the type described above. On the perimeter beams36of the frame30the securing device10A has a modified shape for termination of the screen deck. As shown the upper end13of the body11is a half shape13A to fit the securing cavity21without an abutting screen panel.

Persons familiar with screening assemblies will appreciate that in most cases it will be suitable to secure the edges of panels by conventional methods using beams and clamps. The modified securing device10A provides an optional alternative.

Assembly involves fitting the securing devices10,10A to holes32in the frame30, with or without adapters31. Panels are then pressed onto the securing means12of each securing device10,10A. The securing cavity21resiliently deforms as the screen panel20is forced over the ridge121until a lower part211of the securing cavity21seats against the neck122and an upper part212of the securing cavity21seats against the ridge121. The process is repeated to position an abutting screen panel.

Screen panels20are removed from the securing device10by leveraging the screen panel20away from the securing device10. If a securing device10is damaged it is removed and replaced.

The securing device described in detail above is only one possible embodiment. A number of alternate embodiments are shown inFIG. 8. The embodiment80ofFIG. 8Ais similar to the embodiment ofFIG. 1but with the addition of a securing ridge81on the flange17. The securing ridge mates with a corresponding recess on the underside of a screen panel to provide additional holding strength.

InFIG. 8Bthe embodiment82employs a recess83instead of a ridge121. There will be a corresponding ridge on the inside of the securing cavity21in a screen panel20. The securing means84of embodiment85inFIG. 8Chas a donut profile. A corresponding shape of the securing cavity21in a screen panel20will provide suitable holding strength. Also shown in the embodiment84ofFIG. 8Cis a tapered stub86that may be forced into a hole32in a frame30or a hole34in an adapter31with interference fit. A flange may not be necessary for the embodiment ofFIG. 8Csince the tapered stub86can be forced into hole32or hole34by direct pressure on the upper end13of the body11.

Referring toFIGS. 9 to 11, there is a shown a perspective view of another embodiment of a securing device10. The securing device10consists of a body11having a securing means12at an upper end13. In the embodiment ofFIG. 9, the securing means12consists of an enlarged head91on top of a tapered neck92below. The head91has a circumferential ridge93. The head91is substantially frusto-conical between the ridge93and the upper end of the head91. The frusto-conical section of the head91tapers at an angle of nominally thirty to thirty five degrees. The neck92tapers at an angle of nominally ten to fifteen degrees. The neck92extends from a collar94.

A hole14is formed in the upper end13. The hole14extends through the body11to receive a pin on a screening panel, as described below.

At a lower end15of the body11is a stub16that has pre-cut threads161. As will be described below, the stub16engages a corresponding socket on a support frame of a vibrating screen assembly. Intermediate the upper end13and the lower end15is a flange17. The flange may be round for tightening by hand (as shown inFIG. 9).

Referring toFIG. 12, there is shown a sectional side view of the securing device ofFIG. 9holding adjacent screening panels20. Each screen panel20has a securing cavity21shaped to receive the head91and neck92of the securing means12. The securing cavity21has a half round shape centred on a pin22. The pin22also has a half round shape such that abutting screening panels form a circular cavity with a central circular pin. The circular pin is sized and shaped to fit within the hole14in the upper end13of the securing device10. The relative length and thickness of the pins22allow for ease of capture of the pins22within the hole14.

The circular cavity formed by the abutting securing cavities21serves to locate the screen panels20on the securing device10and the circular pin formed by the abutting pins22locates within the hole14. The combination of the pin and the cavity serves to firmly but removably hold the screen panels20on the securing device10. The shape and configuration of the head91and neck92of the securing means allows for ease of insertion of the securing means12into the circular cavity. The relative thickness and the size of the taper of the head91and neck92are specific for ease of insertion of the securing means12into the circular cavity.

It will be appreciated that the securing means12, securing cavity21, hole14and pin22are not limited to the shapes shown in the preferred embodiment. The securing cavity21may have any shape that corresponds to the shape of the securing means12. The shape of the securing means may be, for example, square or hexagonal. Similarly the hole14may be square or hexagonal. For ease of manufacture a circular shape is preferred.

The structure of a screen panel20is seen most clearly inFIG. 13. Each screen panel20is formed from plastics material, most commonly polyurethane. The screen deck23includes multiple screening apertures such as24. The screen panel20has a perimeter25that is thicker than the screen deck23. The securing cavity21and pin22are formed in the perimeter25at the time of moulding the screen panel.

Assembly involves the same process as described by reference toFIG. 7. Panels20are pressed onto the securing means12of each securing device10. The securing cavity21resiliently deforms as the screen panel20is forced over the ridge93until a seat213of the securing cavity21sits against the collar94, a lower part211of the security cavity21seats against the neck92and an upper part212of the securing cavity21seats against the head91. The process is repeated to position an abutting screen panel.

Screen panels20are removed from the securing device10by leveraging the screen panel20away from the securing device10. If a securing device10is damaged it is removed and replaced.

FIG. 14shows an embodiment of the securing device10in which a thread has not been pre-cut into the stub16. It will be appreciated that a thread can be pre-cut into the stub16for screwing the securing device10into a frame or an adaptor for the frame. Leaving the stub16without a thread facilitates a broader range of possible fixing options.