CA2645317A1 - Wear resistant screen plate - Google Patents
Wear resistant screen plate Download PDFInfo
- Publication number
- CA2645317A1 CA2645317A1 CA 2645317 CA2645317A CA2645317A1 CA 2645317 A1 CA2645317 A1 CA 2645317A1 CA 2645317 CA2645317 CA 2645317 CA 2645317 A CA2645317 A CA 2645317A CA 2645317 A1 CA2645317 A1 CA 2645317A1
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- CA
- Canada
- Prior art keywords
- wear
- plate
- carrier plate
- wear resistant
- screen plate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
- B07B1/00—Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like
- B07B1/46—Constructional details of screens in general; Cleaning or heating of screens
- B07B1/4609—Constructional details of screens in general; Cleaning or heating of screens constructional details of screening surfaces or meshes
- B07B1/469—Perforated sheet-like material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
- B07B1/00—Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like
- B07B1/18—Drum screens
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
- B07B1/00—Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like
- B07B1/46—Constructional details of screens in general; Cleaning or heating of screens
- B07B1/4609—Constructional details of screens in general; Cleaning or heating of screens constructional details of screening surfaces or meshes
Landscapes
- Combined Means For Separation Of Solids (AREA)
Abstract
A wear resistant screen plate comprising a carrier plate having a plurality of apertures and a wear resistant layer formed on the carrier plate such that the plurality of apertures remain substantially unobscured. The wear resistant layer comprises a plurality of wear plates arranged such that a plurality of portions of the carrier plate remain exposed.
Description
WEAR RESISTANT SCREEN PLATE
FIELD OF THE INVENTION
The present invention relates to the field of materials processing.
More particularly, this invention relates to a screen plate having a wear resistant layer.
BACKGROUND OF THE INVENTION
Screen plates are commonly employed in the mining and aggregate industries to separate different grades of material based upon their physical size. The screen plates are sometimes used as flat vibratory screens or they may be arcuate and affixed to the interior of a rotating drum.
Screen plates typically comprise a number of apertures which may be of a variety of shapes. During the sorting process materials such as coal, coke, gravel and ore can be directed onto the screen plate. The finer materials are able to pass through the apertures of the screen plate while larger materials such as rocks and boulders are retained.
The constant collision of these larger abrasive materials with the screen plate means that the material from which the plate is constructed must be extremely strong. Often the screen plate will fail due to wear or stress fractures caused by the large number of screening cycles to which they are exposed or the plate framework between apertures is worn away to allow larger materials through and thereby resulting in the sorting efficiency being compromised.
Screens plates can easily reach sizes of approximately two meters square and weigh over one tonne and so, in addition to the manufacturing costs in making frequent replacements, their maintenance and removal is a substantial operation which also necessitates shutting down operations.
To improve their resistance to wear and thereby improve operational lifetime prior art screen plates often have a 2-3 mm deep hard facing of plasma transfer arc welded tungsten carbide applied to the wear surface.
While providing some benefits, in use the impact of larger rocks causes spalling of the hard and brittle tungsten carbide, particularly at the edges of the screen openings, ultimately leading to failure as wear progresses into the plate body itself.
The applicant's prior filing, Canadian patent no. 2 524 540, presented a solution to the above problems by providing for a protective layer of highly wear resistant material which could be applied to the surface of a carrier plate. The disclosure of this document is hereby incorporated by reference in its entirety.
The protective layer of Canadian patent no. 2 524 540 comprised a multiplicity of relatively small abrasion resistant plates of a material such as Domite arranged so as to form a mosaic which covered the entire wear surface of the carrier plate, apart from the apertures formed therein. The plates overlapped slightly with the apertures of the carrier plate to protect the edges defining the apertures from abrasion.
This arrangement provides significant advantages over the prior art.
The Domite provides good abrasion resistance but, importantly, if any of the abrasion resistant plates were damaged then it would be a relatively simple process to replace one of these plates without the need to remove the entire screen plate. This results in more straightforward maintenance, less downtime and reduced costs in less frequent replacement of the large underlying carrier plate structure.
OBJECT OF THE INVENTION
An object of the invention is to overcome or at least alleviate one or more of the above problems or offer the consumer a useful commercial 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 wear resistant screen plate comprising:
(a) a carrier plate having a plurality of apertures; and (b) a wear resistant layer formed on the carrier plate such that the plurality of apertures remain substantially unobscured;
wherein the wear resistant layer comprises a plurality of wear plates arranged such that a plurality of portions of the carrier plate remain exposed.
Suitably, said portions are located between adjacent apertures.
Preferably, each aperture of the carrier plate has at least two such portions adjacent thereto.
Suitably, each wear plate is spaced from adjacent wear plates by a distance of at least 25mm. Preferably, each wear plate is spaced from adjacent wear plates by a distance of about 38mm.
Each wear plate comprises a wear layer and a contact layer.
FIELD OF THE INVENTION
The present invention relates to the field of materials processing.
More particularly, this invention relates to a screen plate having a wear resistant layer.
BACKGROUND OF THE INVENTION
Screen plates are commonly employed in the mining and aggregate industries to separate different grades of material based upon their physical size. The screen plates are sometimes used as flat vibratory screens or they may be arcuate and affixed to the interior of a rotating drum.
Screen plates typically comprise a number of apertures which may be of a variety of shapes. During the sorting process materials such as coal, coke, gravel and ore can be directed onto the screen plate. The finer materials are able to pass through the apertures of the screen plate while larger materials such as rocks and boulders are retained.
The constant collision of these larger abrasive materials with the screen plate means that the material from which the plate is constructed must be extremely strong. Often the screen plate will fail due to wear or stress fractures caused by the large number of screening cycles to which they are exposed or the plate framework between apertures is worn away to allow larger materials through and thereby resulting in the sorting efficiency being compromised.
Screens plates can easily reach sizes of approximately two meters square and weigh over one tonne and so, in addition to the manufacturing costs in making frequent replacements, their maintenance and removal is a substantial operation which also necessitates shutting down operations.
To improve their resistance to wear and thereby improve operational lifetime prior art screen plates often have a 2-3 mm deep hard facing of plasma transfer arc welded tungsten carbide applied to the wear surface.
While providing some benefits, in use the impact of larger rocks causes spalling of the hard and brittle tungsten carbide, particularly at the edges of the screen openings, ultimately leading to failure as wear progresses into the plate body itself.
The applicant's prior filing, Canadian patent no. 2 524 540, presented a solution to the above problems by providing for a protective layer of highly wear resistant material which could be applied to the surface of a carrier plate. The disclosure of this document is hereby incorporated by reference in its entirety.
The protective layer of Canadian patent no. 2 524 540 comprised a multiplicity of relatively small abrasion resistant plates of a material such as Domite arranged so as to form a mosaic which covered the entire wear surface of the carrier plate, apart from the apertures formed therein. The plates overlapped slightly with the apertures of the carrier plate to protect the edges defining the apertures from abrasion.
This arrangement provides significant advantages over the prior art.
The Domite provides good abrasion resistance but, importantly, if any of the abrasion resistant plates were damaged then it would be a relatively simple process to replace one of these plates without the need to remove the entire screen plate. This results in more straightforward maintenance, less downtime and reduced costs in less frequent replacement of the large underlying carrier plate structure.
OBJECT OF THE INVENTION
An object of the invention is to overcome or at least alleviate one or more of the above problems or offer the consumer a useful commercial 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 wear resistant screen plate comprising:
(a) a carrier plate having a plurality of apertures; and (b) a wear resistant layer formed on the carrier plate such that the plurality of apertures remain substantially unobscured;
wherein the wear resistant layer comprises a plurality of wear plates arranged such that a plurality of portions of the carrier plate remain exposed.
Suitably, said portions are located between adjacent apertures.
Preferably, each aperture of the carrier plate has at least two such portions adjacent thereto.
Suitably, each wear plate is spaced from adjacent wear plates by a distance of at least 25mm. Preferably, each wear plate is spaced from adjacent wear plates by a distance of about 38mm.
Each wear plate comprises a wear layer and a contact layer.
Suitably, the wear layer is substantially comprised of an abrasion resistant material. Preferably, the wear layer is substantially comprised of white iron.
The wear plates comprise a white iron alloy brazed to a mild steel backing.
Suitably, the carrier plate is a mild steel plate.
Further features of the present invention will become apparent from the following detailed description.
Throughout this specification, unless the context requires otherwise, the words "comprise", "comprises" and "comprising" will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.
BRIEF DESCRIPTION OF THE FIGURES
In order that the invention may be readily understood and put into practical effect, preferred embodiments will now be described by way of example with reference to the accompanying figures wherein like reference numerals refer to like parts and wherein:
FIG I shows a plan view of a carrier plate;
FIG 2 shows a cross sectional view of the carrier plate shown in FIG 1;
FIG 3 shows a plan view of a portion of a wear resistant screen plate according to an embodiment of the invention;
FIG 4 shows a cross sectional view of the wear resistant screen plate shown in FIG 3;
FIG 5 is a representation of a portion of the wear resistant screen plate shown in FIG 3 indicating the typical welding areas for the wear plates;
and FIG 6 shows a cross sectional view of a wear plate suitable for use in 5 the present invention.
DETAILED DESCRIPTION OF THE INVENTION
As shown in FIG 1, which is a plan view of a carrier plate, carrier plate 2 has a plurality of apertures 3 extending through its body which are formed in a predetermined pattern. The pattern shown in FIG 1 would be particularly suited to use in a drum in which case the diagonal area 5, which is not provided with apertures 3, would correspond to an underlying structural component of the drum. Bolt apertures 4 are provided to fix carrier plate 2 onto the underlying support structure.
FIG 2 shows a cross sectional view of the carrier plate 2 shown in FIG
1. The arcuate shape of the embodiment of carrier plate 2 shown is apparent and a number of these plates can be envisaged in contact with one another to form the separation surface of a rotating drum. Apertures 3 are seen to pass through the body of the carrier plate 2, as are bolt apertures 4.
Apertures 3 are sized according to the applicable screening application FIG 3 shows a plan view of a portion of a wear resistant screen plate 1 according to one embodiment of the invention. Wear resistant screen plate 1 comprises carrier plate 2 and a wear resistant layer which is made up of a plurality of separate wear plates 10. The wear plates 10 can be seen to be set out in rows with each row being separated by apertures 3. Adjacent wear plates 10 within each row are separated by a minimum distance X which is discussed in more detail below. This results in a plurality of portions 6 of carrier plate 2 remaining exposed. It can be seen that no two wear plates 10 are in contact. Bolt apertures 4 and a diagonal area 5, which may or may not be present, are not indicated in FIG 3 for the sake of convenience.
FIG 4 shows a cross sectional view of the wear resistant screen plate 1 shown in FIG 3. As in FIG 2, the arcuate shape of the particular embodiment of the wear resistant screen plate 1 represented can be seen.
Each wear plate 10 is shown to be made up of a wear layer 11, the surface of which is in direct contact with the abrasive material being sorted, and a weldable contact layer 12 which is in contact with carrier plate 2. The wear plates 10 are attached to carrier plate 2 by welds 13 which hold contact layer 12 in fixed contact with the surface of carrier plate 2.
FIG 5 is a representation of a portion of the wear resistant screen plate 1 shown in FIG 3 indicating the welding areas for the wear plates 10, in one particular embodiment. The detail of carrier plate 2 and wear plates 10 has not been indicated on FIG 5 to enable the pattern of welds 13 to be more clearly visualised. The welds 13 are situated on each edge of the wear plates 10, as viewed from above, and are highlighted in bold lines.
FIG 6 shows a cross sectional view of a wear plate 10 suitable for use in the present invention. As previously mentioned, the wear plate 10 is made up of a wear layer 11 and a contact layer 12.
Although the embodiment shown in FIG 1 is designed to be applied to a drum separator it will be appreciated that the present invention is equally applicable to a vibratory screen plate wherein the screen plate would be flat and not arcuate. The diagonal area 5 may not be present in embodiments in which there are no underlying structural members passing across the underside of carrier plate 2 and so apertures 3 may be evenly distributed over the entire surface of carrier plate 2. Although in the embodiments shown, apertures 3 are substantially square in shape it will be appreciated that they may be formed in a wide variety of shapes so long as they are able to perform the necessary separation of the various sized materials.
The applicant's prior filing, Canadian patent no. 2 524 540, has been discussed above. While the invention disclosed therein represents an improvement over prior art screen plates it has been found that spacing wear plates 10 from one another provides for significant further advances in the operational lifetime of the screen plate while maintaining the protective function of this layer.
Canadian patent no. 2 524 540 taught the use of a protective layer of abrasion resistant plates (ARP's) which cover the entire wear surface of the carrier plate, apart from the screening holes. Individual ARP's abut one other along all of their edges, apart from where they border with a screening hole.
This means that no portions of the carrier plate are left exposed. This continuous, mosaic-like blanket provides good protection for the carrier plate from the abrasive materials being screened.
However, stress analysis work carried out on this design indicated that mechanical loading on the rotating screen plate during normal operation was of a cyclic nature and a degree of flexing of the ARP's would result and thus produce a risk of fatigue failure of the carrier plate at the points where the ARP's abut one another.
The invention described herein provides a solution to this problem by spacing wear plates 10 apart by a critical minimum distance to expose portions 6 of carrier plate 2. In other words no two wear plates 10 are in abutting contact. This spacing, which relates to exposed portions 6, accommodates the natural flexure of wear plates 10 due to the charge load of screening material without placing excessive stress on carrier plate 2.
This results in a significant extension of the operational lifetime of the screen plate and therefore provides considerable savings in repair and screening downtime.
Although certain portions 6 of carrier plate 2 between adjacent wear plates 10 are now exposed, this does not lead to a significant increase in wear on those areas. The spacing between wear plates 10 is such that the larger grade materials which are being screened, and which can potentially cause the most damage, are still prevented from colliding with carrier plate 2 by the surface of wear layer 11 of wear plates 10. This allows only the finer grade materials which do not cause significant stress or abrasion to pass between wear plates 10 and contact the exposed portions 6 of carrier plate 2. The regions of carrier plate 2 which define each aperture 3 are also well protected from abrasion by coarse material by the surrounding wear plates 10.
FIG 3 shows that the portions 6 of carrier plate 2 which are left exposed to the fine material load are located between adjacent apertures 3 and extend further in one dimension than the other such that each aperture of carrier plate 2 has two such exposed portions 6 adjacent thereto.
Thus it can be seen that the present wear resistant screen plate 1 provides two wear zones. The first is the highly wear resistant layer comprising wear plates 10 which encounters high stress abrasion from large rocks and other coarse materials and the second is at the actual surface of carrier plate 2 which is exposed only to low stress abrasion from the flow of fines and consequently has a much lower wear rate.
The actual layout of wear plates 10 and apertures 3 shown in FIG 3 is different to that shown in Canadian patent no. 2 524 540 to accommodate the different design which incorporates the need for a minimum spacing between each wear plate 10.
FIG 3 shows a preferred embodiment of the present wear resistant screening plate 1 wherein adjacent wear plates 10 in a row are separated by a minimum distance X. There are two considerations which must be balanced to determine what value X should take. The first is that the spacing should be sufficient so as to ensure wear plates 10 do not contact one another during flexure to thereby stress the carrier plate 2, as described above. The second consideration is that the distance X should not be so great as to allow larger coarse materials to contact carrier plate 2 and cause abrasive damage. In other words the spaced wear plates 10 still protect the underlying carrier plate 2 from abrasion due to larger grade materials but are spaced enough to allow a normal amount of movement during operation without abuttingly engaging adjacent wear plates 10. The stress concentration on carrier plate 2 in the areas between wear plates 10 is thereby greatly reduced and the likelihood of its failure due to fatigue in these areas is substantially reduced or eliminated.
It has been found that the minimum distance X separating each wear 5 plate 10 should be at least about 25mm. Preferably, each wear plate 10 is spaced apart from the closest adjacent wear plate 10 by a distance of about 38mm.
The actual dimensions of wear plates 10 will vary depending on the size of the carrier plate 2 to be covered. In one embodiment wear plates 10 10 have a length which ranges from about 70 mm to about 155 mm and a width between about 50 mm to about 65 mm, preferably 57 mm.
In FIG 3 the borders of carrier plate 2 are shown as not having been provided with wear plates 10 on their surface. It will be appreciated that, if necessary, these areas may also be provided with spaced wear plates 10 to provide complete protection for carrier plate 2.
FIG 4 shows that wear plates 10 are constructed from two layers.
Wear layer 11 may be constructed from any highly abrasive resistant material. White iron is a particularly suitable material for construction of wear layer 11. Other such highly abrasion resistant materials are readily available and would be known to those of skill in the art. Contact layer 12 may be constructed from a material such as mild steel which does not present welding problems. The wear layer 11 may be attached to the contact layer 12 by a number of methods which are known in the art. In one embodiment wear layer 11 is vacuum brazed to contact layer 12. Particularly suitable examples of such two-layered materials for use as wear plates 10 are available under the trade marks DOMITE and LAMINITE .
Welds 13 are seen to fix wear plates 10 to carrier plate 2. One particular pattern of welding is exemplified in FIG 5. In this embodiment the welds 13 are stitch welds formed from above the wear surface of carrier plate 2 by welding along the edges of contact between carrier plate 2 and contact surface 12 of wear plates 10, other than in the areas of apertures 3. Carrier plate 2 is generally a steel plate. If a wear plate 10 requires replacement the welds holding it in place can conveniently be ground out and the plate simply replaced. This obviates the need to replace or remove the entire carrier plate 2 due to damage in a small region.
FIG 6 shows the two-layered construction of the wear plates 10. The relatively thick and highly abrasion resistant wear layer 11 provides a longer operational lifetime for the screening plate 1 by providing protection from damage due to collisions from large rocks and the like. The contact layer of mild steel or the like sits on the wear surface of carrier plate 2 and is used to secure it thereto by way of one or more welds.
The present invention provides for an effective wear resistant screening plate which has an improved operational lifetime over those in the prior art. The spacing between the wear plates provided on the surface of the carrier plate stems from recognition that the carrier plate surface does not have to be entirely covered with protective abrasion resistant plates. Rather, if the spacing between adjacent wear plates is selected appropriately then the exposed portions of the carrier plate are still protected from wear by larger grade materials and the problems of localised excessive stress due to abutting wear plates causing failure of the carrier plate are substantially reduced or eliminated.
Throughout the specification the aim has been to describe the preferred embodiments of the invention without limiting the invention to any one embodiment or specific collection of features. It will therefore be appreciated by those of skill in the art that, in light of the instant disclosure, various modifications and changes can be made in the particular embodiments exemplified without departing from the scope of the present invention.
The wear plates comprise a white iron alloy brazed to a mild steel backing.
Suitably, the carrier plate is a mild steel plate.
Further features of the present invention will become apparent from the following detailed description.
Throughout this specification, unless the context requires otherwise, the words "comprise", "comprises" and "comprising" will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.
BRIEF DESCRIPTION OF THE FIGURES
In order that the invention may be readily understood and put into practical effect, preferred embodiments will now be described by way of example with reference to the accompanying figures wherein like reference numerals refer to like parts and wherein:
FIG I shows a plan view of a carrier plate;
FIG 2 shows a cross sectional view of the carrier plate shown in FIG 1;
FIG 3 shows a plan view of a portion of a wear resistant screen plate according to an embodiment of the invention;
FIG 4 shows a cross sectional view of the wear resistant screen plate shown in FIG 3;
FIG 5 is a representation of a portion of the wear resistant screen plate shown in FIG 3 indicating the typical welding areas for the wear plates;
and FIG 6 shows a cross sectional view of a wear plate suitable for use in 5 the present invention.
DETAILED DESCRIPTION OF THE INVENTION
As shown in FIG 1, which is a plan view of a carrier plate, carrier plate 2 has a plurality of apertures 3 extending through its body which are formed in a predetermined pattern. The pattern shown in FIG 1 would be particularly suited to use in a drum in which case the diagonal area 5, which is not provided with apertures 3, would correspond to an underlying structural component of the drum. Bolt apertures 4 are provided to fix carrier plate 2 onto the underlying support structure.
FIG 2 shows a cross sectional view of the carrier plate 2 shown in FIG
1. The arcuate shape of the embodiment of carrier plate 2 shown is apparent and a number of these plates can be envisaged in contact with one another to form the separation surface of a rotating drum. Apertures 3 are seen to pass through the body of the carrier plate 2, as are bolt apertures 4.
Apertures 3 are sized according to the applicable screening application FIG 3 shows a plan view of a portion of a wear resistant screen plate 1 according to one embodiment of the invention. Wear resistant screen plate 1 comprises carrier plate 2 and a wear resistant layer which is made up of a plurality of separate wear plates 10. The wear plates 10 can be seen to be set out in rows with each row being separated by apertures 3. Adjacent wear plates 10 within each row are separated by a minimum distance X which is discussed in more detail below. This results in a plurality of portions 6 of carrier plate 2 remaining exposed. It can be seen that no two wear plates 10 are in contact. Bolt apertures 4 and a diagonal area 5, which may or may not be present, are not indicated in FIG 3 for the sake of convenience.
FIG 4 shows a cross sectional view of the wear resistant screen plate 1 shown in FIG 3. As in FIG 2, the arcuate shape of the particular embodiment of the wear resistant screen plate 1 represented can be seen.
Each wear plate 10 is shown to be made up of a wear layer 11, the surface of which is in direct contact with the abrasive material being sorted, and a weldable contact layer 12 which is in contact with carrier plate 2. The wear plates 10 are attached to carrier plate 2 by welds 13 which hold contact layer 12 in fixed contact with the surface of carrier plate 2.
FIG 5 is a representation of a portion of the wear resistant screen plate 1 shown in FIG 3 indicating the welding areas for the wear plates 10, in one particular embodiment. The detail of carrier plate 2 and wear plates 10 has not been indicated on FIG 5 to enable the pattern of welds 13 to be more clearly visualised. The welds 13 are situated on each edge of the wear plates 10, as viewed from above, and are highlighted in bold lines.
FIG 6 shows a cross sectional view of a wear plate 10 suitable for use in the present invention. As previously mentioned, the wear plate 10 is made up of a wear layer 11 and a contact layer 12.
Although the embodiment shown in FIG 1 is designed to be applied to a drum separator it will be appreciated that the present invention is equally applicable to a vibratory screen plate wherein the screen plate would be flat and not arcuate. The diagonal area 5 may not be present in embodiments in which there are no underlying structural members passing across the underside of carrier plate 2 and so apertures 3 may be evenly distributed over the entire surface of carrier plate 2. Although in the embodiments shown, apertures 3 are substantially square in shape it will be appreciated that they may be formed in a wide variety of shapes so long as they are able to perform the necessary separation of the various sized materials.
The applicant's prior filing, Canadian patent no. 2 524 540, has been discussed above. While the invention disclosed therein represents an improvement over prior art screen plates it has been found that spacing wear plates 10 from one another provides for significant further advances in the operational lifetime of the screen plate while maintaining the protective function of this layer.
Canadian patent no. 2 524 540 taught the use of a protective layer of abrasion resistant plates (ARP's) which cover the entire wear surface of the carrier plate, apart from the screening holes. Individual ARP's abut one other along all of their edges, apart from where they border with a screening hole.
This means that no portions of the carrier plate are left exposed. This continuous, mosaic-like blanket provides good protection for the carrier plate from the abrasive materials being screened.
However, stress analysis work carried out on this design indicated that mechanical loading on the rotating screen plate during normal operation was of a cyclic nature and a degree of flexing of the ARP's would result and thus produce a risk of fatigue failure of the carrier plate at the points where the ARP's abut one another.
The invention described herein provides a solution to this problem by spacing wear plates 10 apart by a critical minimum distance to expose portions 6 of carrier plate 2. In other words no two wear plates 10 are in abutting contact. This spacing, which relates to exposed portions 6, accommodates the natural flexure of wear plates 10 due to the charge load of screening material without placing excessive stress on carrier plate 2.
This results in a significant extension of the operational lifetime of the screen plate and therefore provides considerable savings in repair and screening downtime.
Although certain portions 6 of carrier plate 2 between adjacent wear plates 10 are now exposed, this does not lead to a significant increase in wear on those areas. The spacing between wear plates 10 is such that the larger grade materials which are being screened, and which can potentially cause the most damage, are still prevented from colliding with carrier plate 2 by the surface of wear layer 11 of wear plates 10. This allows only the finer grade materials which do not cause significant stress or abrasion to pass between wear plates 10 and contact the exposed portions 6 of carrier plate 2. The regions of carrier plate 2 which define each aperture 3 are also well protected from abrasion by coarse material by the surrounding wear plates 10.
FIG 3 shows that the portions 6 of carrier plate 2 which are left exposed to the fine material load are located between adjacent apertures 3 and extend further in one dimension than the other such that each aperture of carrier plate 2 has two such exposed portions 6 adjacent thereto.
Thus it can be seen that the present wear resistant screen plate 1 provides two wear zones. The first is the highly wear resistant layer comprising wear plates 10 which encounters high stress abrasion from large rocks and other coarse materials and the second is at the actual surface of carrier plate 2 which is exposed only to low stress abrasion from the flow of fines and consequently has a much lower wear rate.
The actual layout of wear plates 10 and apertures 3 shown in FIG 3 is different to that shown in Canadian patent no. 2 524 540 to accommodate the different design which incorporates the need for a minimum spacing between each wear plate 10.
FIG 3 shows a preferred embodiment of the present wear resistant screening plate 1 wherein adjacent wear plates 10 in a row are separated by a minimum distance X. There are two considerations which must be balanced to determine what value X should take. The first is that the spacing should be sufficient so as to ensure wear plates 10 do not contact one another during flexure to thereby stress the carrier plate 2, as described above. The second consideration is that the distance X should not be so great as to allow larger coarse materials to contact carrier plate 2 and cause abrasive damage. In other words the spaced wear plates 10 still protect the underlying carrier plate 2 from abrasion due to larger grade materials but are spaced enough to allow a normal amount of movement during operation without abuttingly engaging adjacent wear plates 10. The stress concentration on carrier plate 2 in the areas between wear plates 10 is thereby greatly reduced and the likelihood of its failure due to fatigue in these areas is substantially reduced or eliminated.
It has been found that the minimum distance X separating each wear 5 plate 10 should be at least about 25mm. Preferably, each wear plate 10 is spaced apart from the closest adjacent wear plate 10 by a distance of about 38mm.
The actual dimensions of wear plates 10 will vary depending on the size of the carrier plate 2 to be covered. In one embodiment wear plates 10 10 have a length which ranges from about 70 mm to about 155 mm and a width between about 50 mm to about 65 mm, preferably 57 mm.
In FIG 3 the borders of carrier plate 2 are shown as not having been provided with wear plates 10 on their surface. It will be appreciated that, if necessary, these areas may also be provided with spaced wear plates 10 to provide complete protection for carrier plate 2.
FIG 4 shows that wear plates 10 are constructed from two layers.
Wear layer 11 may be constructed from any highly abrasive resistant material. White iron is a particularly suitable material for construction of wear layer 11. Other such highly abrasion resistant materials are readily available and would be known to those of skill in the art. Contact layer 12 may be constructed from a material such as mild steel which does not present welding problems. The wear layer 11 may be attached to the contact layer 12 by a number of methods which are known in the art. In one embodiment wear layer 11 is vacuum brazed to contact layer 12. Particularly suitable examples of such two-layered materials for use as wear plates 10 are available under the trade marks DOMITE and LAMINITE .
Welds 13 are seen to fix wear plates 10 to carrier plate 2. One particular pattern of welding is exemplified in FIG 5. In this embodiment the welds 13 are stitch welds formed from above the wear surface of carrier plate 2 by welding along the edges of contact between carrier plate 2 and contact surface 12 of wear plates 10, other than in the areas of apertures 3. Carrier plate 2 is generally a steel plate. If a wear plate 10 requires replacement the welds holding it in place can conveniently be ground out and the plate simply replaced. This obviates the need to replace or remove the entire carrier plate 2 due to damage in a small region.
FIG 6 shows the two-layered construction of the wear plates 10. The relatively thick and highly abrasion resistant wear layer 11 provides a longer operational lifetime for the screening plate 1 by providing protection from damage due to collisions from large rocks and the like. The contact layer of mild steel or the like sits on the wear surface of carrier plate 2 and is used to secure it thereto by way of one or more welds.
The present invention provides for an effective wear resistant screening plate which has an improved operational lifetime over those in the prior art. The spacing between the wear plates provided on the surface of the carrier plate stems from recognition that the carrier plate surface does not have to be entirely covered with protective abrasion resistant plates. Rather, if the spacing between adjacent wear plates is selected appropriately then the exposed portions of the carrier plate are still protected from wear by larger grade materials and the problems of localised excessive stress due to abutting wear plates causing failure of the carrier plate are substantially reduced or eliminated.
Throughout the specification the aim has been to describe the preferred embodiments of the invention without limiting the invention to any one embodiment or specific collection of features. It will therefore be appreciated by those of skill in the art that, in light of the instant disclosure, various modifications and changes can be made in the particular embodiments exemplified without departing from the scope of the present invention.
Claims (11)
1. A wear resistant screen plate comprising:
(a) a carrier plate having a plurality of apertures; and (b) a wear resistant layer formed on the carrier plate such that the plurality of apertures remain substantially unobscured;
wherein the wear resistant layer comprises a plurality of wear plates arranged such that a plurality of portions of the carrier plate remain exposed.
(a) a carrier plate having a plurality of apertures; and (b) a wear resistant layer formed on the carrier plate such that the plurality of apertures remain substantially unobscured;
wherein the wear resistant layer comprises a plurality of wear plates arranged such that a plurality of portions of the carrier plate remain exposed.
2. The wear resistant screen plate of claim 1 wherein said portions are located between adjacent apertures.
3. The wear resistant screen plate of claim 1 or claim 2 wherein each aperture of the carrier plate has at least two such portions adjacent thereto.
4. The wear resistant screen plate of claim 1 wherein each wear plate is spaced from adjacent wear plates by a distance of at least 25mm.
5. The wear resistant screen plate of claim 4 wherein each wear plate is spaced from adjacent wear plates by a distance of about 38mm.
6. The wear resistant screen plate of claim 1 wherein each wear plate comprises a wear layer and a contact layer.
7. The wear resistant screen plate of claim 6 wherein the wear layer is substantially comprised of an abrasion resistant material.
8. The wear resistant screen plate of claim 6 wherein the wear layer is substantially comprised of white iron.
9. The wear resistant screen plate of claim 6 wherein the contact layer is substantially comprised of mild steel.
10. The wear resistant screen plate of claim 6 wherein the wear layer is brazed onto the contact layer.
11. The wear resistant screen plate of claim 1 wherein the carrier plate is a mild steel carrier plate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2645317A CA2645317C (en) | 2008-11-27 | 2008-11-27 | Wear resistant screen plate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2645317A CA2645317C (en) | 2008-11-27 | 2008-11-27 | Wear resistant screen plate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2645317A1 true CA2645317A1 (en) | 2010-05-27 |
| CA2645317C CA2645317C (en) | 2014-07-22 |
Family
ID=42211997
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2645317A Active CA2645317C (en) | 2008-11-27 | 2008-11-27 | Wear resistant screen plate |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2645317C (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8919567B2 (en) | 2011-10-12 | 2014-12-30 | Syncrude Canada Ltd. | Screen cloth for vibrating or stationary screens |
| WO2017009288A1 (en) * | 2015-07-16 | 2017-01-19 | Thyssenkrupp Industrial Solutions Ag | Screen segment comprising wear-resistant elements |
| US9724732B2 (en) | 2014-08-05 | 2017-08-08 | Syncrude Canada Ltd. | Screen cloth for vibrating, rotating or stationary screens |
| CN110813688A (en) * | 2019-11-27 | 2020-02-21 | 徐州佳禾农业科技有限公司 | Seed production is with classified screening device |
| CN111185378A (en) * | 2019-12-10 | 2020-05-22 | 日昌升建筑新材料设计研究院有限公司 | Block type double-layer composite wear-resistant sieve plate and manufacturing process thereof |
-
2008
- 2008-11-27 CA CA2645317A patent/CA2645317C/en active Active
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8919567B2 (en) | 2011-10-12 | 2014-12-30 | Syncrude Canada Ltd. | Screen cloth for vibrating or stationary screens |
| US9724732B2 (en) | 2014-08-05 | 2017-08-08 | Syncrude Canada Ltd. | Screen cloth for vibrating, rotating or stationary screens |
| WO2017009288A1 (en) * | 2015-07-16 | 2017-01-19 | Thyssenkrupp Industrial Solutions Ag | Screen segment comprising wear-resistant elements |
| CN110813688A (en) * | 2019-11-27 | 2020-02-21 | 徐州佳禾农业科技有限公司 | Seed production is with classified screening device |
| CN111185378A (en) * | 2019-12-10 | 2020-05-22 | 日昌升建筑新材料设计研究院有限公司 | Block type double-layer composite wear-resistant sieve plate and manufacturing process thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CA2645317C (en) | 2014-07-22 |
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| EEER | Examination request |
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