Note: Descriptions are shown in the official language in which they were submitted.
CA 02708325 2010-06-22
1
REPLACEABLE WEAR LINER
Field of the Invention
This invention relates to the field of wear liners, and in particular to
replaceable wear
liners.
Background of the Invention
Many industrial processes involve the transport of a workflow material
feedstock along a
channel or trough. The workflow material may often be abrasive. A traditional
approach is to
provide the trough with a liner, whether along a bottom portion thereof of
along side portions as
well as a bottom portion. In the past replaceable sacrificial wear liners,
most typically steel wear
liners, have been used. Very often these wear liners have been held in place
by mechanical
fasteners, such as threaded fasteners, often welded threaded rod studs, that
protrude downwardly
through the chute structure, and that are fastened from the outsides.
Summary of the Invention
In an aspect of the invention there is a a wear member. It has a body having
at least a
first accommodation defined therein. The body has a width, a breadth and a
thickness. Each of
the width and breadth is greater in magnitude than the thickness. There is at
least a first
magnetic member, the first magnetic member being seated in the first
accommodation. The
body has a first portion, a second portion, and a peripheral wall. The first
portion is made of a
first material. The first portion extends predominantly width-wise and breadth-
wise, and
overlies the first magnetic member. The second portion underlies the first
magnetic member.
The peripheral wall extends about the magnetic member. The first material is a
non-
magnetizable, non-brittle, consumable wear material. The first material has a
first modulus of
elasticity. The magnetic material has a modulus of elasticity. The first
modulus of elasticity of
the first material is at least an order of magnitude smaller than the modulus
of elasticity of the
first magnetic member. The second portion is magnetically transparent. The
body defines a
footprint of the wear member for seating on a magnetically attractive
substrate. When in use the
second portion extends between the first magnetic material and the
magnetically attractive
substrate.
CA 02708325 2010-06-22
2
In a feature of that aspect of the invention the second portion established a
stand-off
distance between the first magnetic member and the underlying magnetically
attractive substrate.
In another feature, the first portion is substantially thicker than the second
portion, and the
second portion is substantially thinner than the first magnetic member. In
another feature, the
first portion, the second portion and the first magnetic member, taken
together, have an overall
thickness, and at least one of. (a) the first portion overlying said first
magnetic member is at
least five times as thick as the second portion underlying said magnetic
member; (b) the first
portion is at least one third as thick as the overall thickness; (c) the
second portion underlying
said first magnetic member is less than 1/20 as thick as the overall
thickness; and (d) each of the
length and the breadth is more than 3 times as great as the overall thickness.
In still another
feature, the wear member is one in which at least one of (a) the first portion
is made of a
polymeric material; (b) the second portion is made of a polymeric material;
and (c) the first and
second portions, are made of the same polymeric material.
In still another feature, the first magnetic member and any additional
magnetic members
are encapsulated within the body. In another feature, the first portion, the
second portion, and
the peripheral wall form a unified assembly that is one of (a) a monolithic
polymer based
casting; (b) a vulcanized rubber-based member; (c) an assembly of permanently
fused
polymeric members encapsulating the first magnetic member and any other
magnetic member
thereof. In still another feature, any one of: (a) the second portion is made
of a flexible
polymeric material that defines, in use, a seal against the magnetically
attractive substrate; and
(b) the second portion has a compressible seal member mounted thereto, the
compressible seal
member being operable in use to define a seal against the magnetically
attractive substrate. In
yet another feature, the wear member has the form of a repeating shape for use
in a mosaic of
repeating shapes to extend width-wise and breadth-wise substantially
continuously to cover the
magnetically attractive substrate. In another feature the wear member is held
to the substrate
only by magnetic force.
In another feature, the body includes an array of the accommodations defined
therein. A
plurality of magnetic members is seated in a plurality of accommodations of
the array of
accommodations. The body has a partition matrix therewithin. The partition
matrix maintains
between integers of the plurality of magnetic members, at least one of (a)
breadth-wise spacing;
and (b) width-wise spacing. In a further additional feature, the peripheral
wall has a wall
thickness comparable to the spacing between the integers of the plurality of
magnetic members.
In another further additional feature, the body is more flexible than each
integer of the plurality
CA 02708325 2010-06-22
3
of magnetic members whereby the body permits a measure of flexure between
adjacent integers
of the plurality of magnetic members.
In another aspect of the invention there is the combination of a trough
structure that
includes has a magnetically attractive substrate mentioned above, and a
plurality of wear
members as mentioned above, whether including or not including various ones of
the other,
additional, or further features above numerated. The integers of the plurality
of wear members is
laid side-by-side across and along the trough structure to define a wear liner
pad array positioned
to protect the magnetically attractive substrate from workflow materials
passing along the trough
structure. In another feature the wear members are retained in the trough
structure and are free
of mechanical fastenings. In a still further feature, all of the magnetic
members share a common
orientation of polarity predominantly normal to the second portion.
In another aspect of the invention there is a wear pad member for use as one
integer of an
array of wear pads for lining a trough structure, the trough structure
including magnetically
attractive material. The wear pad has a plurality of magnetic members; and a
body, the body
having a first portion, a second portion and a third portion. The third
portion of the body has
accommodations therein for each magnetic member of the plurality of magnetic
members. The
first portion overlies the third portion, the first portion being made of a
consumable polymeric
wear material. The second portion underlies the third portion. The second
portion is
magnetically transparent. The second portion establishes a stand-off distance
between each
magnetic member and the trough structure. The first and second portions have
respective
thicknesses. The thickness of the first portion is greater than the thickness
of the second portion.
In another feature of that aspect of the invention the wear pad member is one
in which
any one of. (a) the first, second, and third portions are made of rubber based
material and are
cured into a single rubber monolith; and (b) the body is made at least
predominantly of molded
polymeric material and the plurality of magnetic members is cast within the
molded polymeric
material. In a further feature the magnetic members of the plurality of
magnetic members are
encapsulated within the body; and the body includes internal spacers
positioned to separate
adjacent integers of the magnetic members side-by-side. In still another
feature, all of the
magnetic members have substantially the same polar orientation predominantly
normal to the
second portion.
In another aspect of the invention there is a magnetically attractive trough
structure and a
plurality of wear pads as described above, which may include the other,
additional or further
CA 02708325 2010-06-22
4
features hereinabove enumerated, the wear pads being mounted in a cross-wise
and lengthwise
tile array to protect the trough structure.
In still another aspect of the invention there is a method of protecting a
structure made of
a magnetically attractive material. The method includes providing a plurality
of magnetically
attractive wear pad members in any of the variations noted above, those wear
pad members
being for use as integers of an array of wear pads; and laying the wear pads
side-by-side in a tile
pattern on a surface of the structure. In a feature of that aspect of the
invention the structure is a
trough.
In a further feature of that method, the method includes removing a pre-
existing steel
wear liner prior to laying the wear pads in the trough. In still another
feature, the trough includes
apertures for mechanical fasteners for attaching the pre-existing steel wear
liner, and the method
includes at least one of: (a) welding the apertures closed; and (b)
positioning the wear pads to
cover locations of the apertures.
In still another aspect of the invention there is a method of making a
magnetic wear pad
for use in a magnetically attractive trough structure. The method includes
placing a thin layer of
magnetically transparent polymeric material in a mold against a first mold
surface; locating a
plurality of magnetic members in the mold in spaced apart positions; filling
the mold with a
balance of polymeric material overlying the magnetic members, that balance of
material
including a layer of polymeric material thicker than the thin layer; and
curing the material.
In a further feature of that method, the polymeric material of the thin layer
and of the
balance is a rubber based material, and the method includes vulcanizing the
rubber based
material hermetically to seal the magnetic members hermetically therewithin.
Brief Description of the Drawings
These and other aspects of the invention may be more readily understood with
the aid of
the illustrative Figures included herein below, showing of an example, or
examples, embodying
the various aspects of the invention, provided by way of illustration, but not
of limitation of the
present invention, and in which:
CA 02708325 2010-06-22
Figure 1 a is a general arrangement view of a trough having an array of wear
pads
mounted therein according to an aspect of the invention, the near side
wall of the trough being omitted for clarity;
Figure lb is a half cross-section of the trough of Figure la;
5 Figure 1c is a half-cross-section of an alternate trough to that of Figure
1b;
Figure ld is a partially sectioned agitation tank showing another application
of
wear pads in an alternate embodiment to that of Figure 1a;
Figure 2a is a perspective view of a wear pad of the array of Figure 1a;
Figure 2b is a top view of the wear pad of Figure 2a;
Figure 2c is a side view of the wear pad of Figure 2a;
Figure 2d is a vertical section of the wear pad of Figure 2b on `2d - 2d';
Figure 2e is an horizontal section of the wear pad of Figure 2c on `2e - 2e'
with
magnetic materials not installed;
Figure 3a is a perspective view of an alternate wear pad to that of Figure 2a;
Figure 3b is a sectional view of the wear pad of Figure 3a taken on `3b - 3b';
Figure 4a is a cross-sectional view similar to Figure 2e of an alternate wear
pad
to that of Figure 2a, again with out magnetic members;
Figure 4b is a section similar to Figure 2d of the wear pad of Figure 4a.
Detailed Description
The description that follows, and the embodiments described therein, are
provided by
way of illustration of an example, or examples, of particular embodiments of
the principles of
the present invention. These examples are provided for the purposes of
explanation, and not of
limitation, of those principles and of the invention. In the description, like
parts are marked
throughout the specification and the drawings with the same respective
reference numerals. The
drawings are substantially to scale, except where noted otherwise, such as in
those instances in
which proportions may have been exaggerated in order more clearly to depict
certain features of
the invention.
Following from Phillips v. A WH Corp., definitions provided in the
specification are
intended to supplant any dictionary definition, and to prevent interpretation
in the US Patent
Office (or in any other Patent Office) that strays from the customary and
ordinary meaning of the
terms provided herein.
CA 02708325 2010-06-22
= 6
To commence, Figures 1a is a general arrangement view of a trough having an
array of
wear pads mounted therein, indicated generally as 20. The trough or chute, or
duct, or flume, or
sluice, or channel, however it may be called, has a structure 22, which may
include supports 24
and a wall structure 26 that may include a base wall, or back, or bottom panel
30, and left and
right hand side panels, 32, 34.
Generally speaking, trough 20 is intended to be a transport conduit for some
kind of
workflow. The workflow may tend to be particulate, and may tend to be
abrasive. For example,
the workflow may be crushed aggregate, be it sand, gravel, or crushed rock
ore, whether in a
continuous unsorted stream or sorted according to a maximum (or minimum, or
both) grid size
as through a series of sizing screens. The stream of material may be a
metallic or other ore, or
may be coal. Likewise it may be plastic pellet stock, or grain, or some other
particulate material.
It may be a material feedstock flow of foodstuffs, such as carrots, turnips,
potatoes, or such like.
Typically, if not universally, trough 20 may be inclined, such that the force
of gravity
may tend to urge the workflow material along trough 20 from an inlet end 36 to
an outlet end 38,
inlet end 36 being elevated relative to outlet end 38. The illustration
provided should not be
taken as necessarily being proportionate in the length direction. The length
may be very short, a
few feet perhaps, or may be very long, several hundred or thousand feet long,
depending on the
application. For the purposes of description, the length direction may be
considered to be
potentially infinitely long as compared to the width direction. In respect of
trough 20, the flow
direction may be defined as being the longitudinal or axial or x-direction of
the trough. The
cross-wise or transverse direction may be defined as the y-direction, and the
through thickness
direction may be defined as the z-direction. For the purposes of this
description the width-wise
direction follows the arc of the surface of the trough. I. e., the through
thickness is normal to the
trough wall, whatever the orientation of the particular portion of the trough
wall may be.
Typically, also, the workflow material may have the form of a slurry in which
the solid
particulate may be aided in its travel by a fluid transport medium, whether it
be a liquid, such as
water or oil, or a gas such as might involve a fluidized bed. Without
departing from the
generality of the foregoing, for the purposes of ease of conceptual
understanding the workflow
may be taken as being a waterborne or water-assisted flow of a crushed rock
ore.
Also, typically, the trough may define a flow channel of constant cross-
section. This
need not necessarily be the case. The trough may taper somewhat like a funnel,
or diverge like a
diffuser, as may be appropriate to the process in question.
CA 02708325 2010-06-22
7
The flanks or side panels 32, 34 of trough 20, seen in cross-section, may be
angled at 90
degrees to the main or back or bottom panel as in Figure la, though this need
not be so. Side
panels 32, 34 could be angled at some greater included angle, be it 105
degrees, 120 degrees, 135
(as in Figure lc) degrees or 150 degrees, or such other angle as may be
suitable for the process in
question, such that trough 20 is narrower at bottom panel 30 than at the
distal or upper margins
of side panels 32, 34. It may also be that trough 20 is made of more than
three panels, including
additional wall panels or segments 38, as suggested in Figure ic, and it may
be that trough 20 is
not made of distinct panels, but rather of a continuously bent surface,
whether that surface is a
circular arc or some other arc or combination of arcs or arcs and tangent
portions of the same or
different radii of curvature. It is also typical that trough 20 is straight in
the longitudinal or x-
direction, though in the most general case this need not be so. I. e., trough
20 could be curved, or
could have corners in the path direction. However, for the simplicity of
discussion, it will be
taken that trough 20 is straight in the longitudinal direction.
In each case, however, the containing or base structure 22 of the trough
presents an inner
surface 40 that is suitable for lining with an array 42 of tiles 48, namely
the wear resistant
assemblies or pads 50 described herein. Pads 50 each have a breadth b50, a
width w50, and a
through thickness to. The width and breadth extending in width-wise and
breadthwise
directions that, as installed run lengthwise and cross-wise with respect to
the surface of the
trough, whereas the thickness is generally normal to the trough surface.
Although the present description is cast predominantly in the context of wear
liner pads
for troughs, more generically wear pad assemblies 50 may be used in a variety
of applications in
which a structural member is to be protected from damage by, for example,
abrasive objects or
impact such as may occur when aggregate is dumped upon or against it. For
example, wear pads
50 may be used to line a flat sorting table surface. That table surface may be
neither tilted nor
bounded by upstanding side retaining walls or fences, or it may have such
incline, taper,
sidewalls or guides, and so on, as may be appropriate. By way of another
example, such pads
may be used to line agitation tanks, such as tank 44 shown in partial section
in Figure Id. In
these instances, the square root of the planar or generally surface-wise
breadth and width surface
area may be taken as a dominant or characteristic dimension for comparison
against through
thickness, and in each case the square root of the area may tend to be at
least three times the
overall through-thickness of the pad, and perhaps in the range of 6 times, or
more, than such
through thickness.
CA 02708325 2010-06-22
= 8
Each tile 48 of array 42, namely each wear liner pad assembly 50, may have
breadth and
width dimensions substantially greater than the through-thickness dimension,
such that their
characterization as being predominantly, or approximating substantially,
planar (or
predominantly trough surface-wise) extending tiles or plates is appropriate.
It will be understood
that more generically, a wear pad 50 need not be of a shape that would
necessarily be reasonably
characterised as a "tile". In most instances the breadth and width may be
taken as being very
substantially greater than the through-thickness, but in any case may be more
than about two and
a half or three times the overall through-thickness. More typically, it may be
in the range of 4 to
times the through-thickness. Pads of different aspect ratios may be made, as
suggested by
10 thinner pad assembly 52 in Figures 3a and 3b.
While tiles 48 may tend to be substantially planar, this need not be so. Where
the inside
surface of trough 20 is curved, the tiles may be formed in such manner as may
be appropriate for
following that curve. An example of such a curved tile is pad assembly 46 of
tank 44, which is
formed on a portion of a cylindrical arc to mate with the cylindrical
containment wall of tank 44
of Figure Id. Further, as explained below, tiles 48, i.e., pad assemblies 50,
may each have an
ability to flex to an extent that may facilitate accommodation of an
underlying curved
embodiment of surface 40 that may tolerate or accommodate local defects or
asperities in
underlying trough structure 22. Without departing from the generality of this
description, from
this point for ease of conceptual understanding the description shall proceed
on the basis of pad
assemblies 50 as approximating flat and planar tiles.
Each of tiles 48 has an outer peripheral shape when viewed on a projection
normal to the
plane of breadth-wise (or transverse) and depth-wise (or longitudinal) extent.
It may be that a
plurality of tiles of one shape, and only one shape, may be employed.
Alternatively, there may
be a pattern of tiles of two or more different shapes (e.g., octagons and
squares; hexagons and
diamonds; hexagons and triangles, and so on, there being many possibilities)
that may be used to
form a mosaic or repeating pattern of wear plates. The shape of each tile 48
does not need to be
a regular polygon. It may, for example, be to some extent arbitrary, and may
be interlocking.
The shape of the pad may be circular as pad assembly 54 in Figure Id, or part
of a pie shaped, or
truncated pie-shaped sector as pad assemblies 56 and 58 also in Figure Id.
However, and
without limiting the generality of the foregoing, it may tend to be convenient
for all of the pads
to be of one regular shape. That shape could be a regular hexagon, but it is
still more convenient
that the shape be a quadrilateral having right-angled corners, whether a
rectangle or a square,
though most conveniently a square, such that a person installing the tiles
need not be concerned
with which direction is lengthwise, and which direction is cross-wise. This
may tend to result in
CA 02708325 2010-06-22
9
a tile having six faces, namely a bottom, a top, left hand, right hand, front
(i.e., upstream) and
rear (i.e., downstream). In the case of a square tile, left, right, front and
rear may be arbitrary.
The structural members of trough 20 may tend to be made of a magnetically
attractive
material, such as mild steel. In the most general case, it may be that this
magnetically attractive
material of trough 20 is itself made of magnetic material or of material upon
which a magnetic
field is imposed externally, as by magnetising the material of making it part
of an
electromagnetic circuit; or, alternatively it may be a material that can be
attracted to a magnet,
such as a ferromagnetic material which may be pure iron or some alloy of iron,
whether
including nickel or chrome or some other alloying element. It may also be that
the walls of the
trough are made of magnetically transparent material backed by magnetically
attractive material.
Without departing from the generality of the foregoing, the material of trough
20 may most
commonly be thought of as an un-magnetized mild steel. In some industries,
such as a food
processing industry, or in a coloured-plastic pellet application in which
colour contamination is
to be avoided, for example, the material may be a grade of stainless steel.
Pad assembly 50 may be employed in either a new trough, or as a replacement
lining
member for an existing trough. To the extent that pads 50 may be used for
retrofit, trough 20
may previously have been lined with different wear liner materials, such as
high hardness steel
plate. It may be noted that in the past these steel wear liner plates have
tended to be large, and
therefore heavy, and have tended to require replacement of the entire wear
liner even where only
a portion, such as a central portion, of the wear liner has worn out. Inasmuch
as wear liners have
tended to have been made of abnormally hard steels, this replacement may have
been relatively
expensive.
Previous wear liner materials may have been held in place by, for example,
threaded
studs mounted to protrude from the backside, or bottom, thereof. The structure
of the trough
may have had corresponding apertures formed therein to permit those studs to
protrude, thereby
providing an element for securement with a corresponding threaded nut, washer,
and lock
washer.
Chutes or channels, or tables, or tanks, of this nature tend to be employed in
high
vibration or repetitive shock loading contexts. A common challenge with
existing wear liners
that are bolted to the underlying structure employing threaded studs is the
tendency of those stud
connections to loosen, or to fret, and, eventually, to leak. Where the flow
material is wet, or is
carried along by water, the tendency of the trough to leak at fastening points
may generally be
CA 02708325 2010-06-22
undesirable. Of course, anti-vibration nuts with nylon inserts, or wired
crenelated nuts, may also
have been used. However fastenings of this nature may have a tendency to work
loose, to be
corrosion initiation sites and so on. While fastener apertures may be welded
closed subsequently
with plug welds to fill those holes (and ground flush), it may also be that
the holes remain
5 without being filled.
Pad assembly 50 has a body, 60, that has the shape of a tile 48 as previously
discussed.
Body 60 includes a first layer or first portion 62, a second layer or second
portion 64, and a
peripheral wall 66 . Peripheral wall 66, and hence more generally body 60, has
a cavity, or
10 internal space, or void, or chamber, such as may be designated as a first
accommodation 68
defined therewithin. A magnetic member 70 is seated within this accommodation.
Adopting the
frame of reference of the trough or channel structure, if the bottom of the
channel is considered
to be underneath pad 50, then first layer or first portion 62 may be
considered to be a layer that
overlies accommodation 68 and magnetic member 70, second layer or second
portion 64
underlies accommodation 68 and magnetic member 70. The third portion, being
that of
peripheral wall 66, is then sandwiched between first portion 62 and second
portion 64.
Pad assembly 50 may have a plurality of accommodations 68, and a plurality of
magnetic
members 70. Typically, though not necessarily, the number of magnetic members
70 may be
equal to the number of accommodations 68, although it may be less. To the
extent that there is a
plurality of accommodations 68, those accommodations may be identified as 72,
74, 76, 78, 80
and 82, as shown in Figure 2e. It is not necessary that these accommodations
be of the same
size, or of the same shape, or that they be rectangular. However, it may be
convenient that they
be four-sided polygons with right angled corners, e.g,, rectangular as shown.
The various
magnetic members need not necessarily be the same size and shape as the
accommodations into
which they seat, but, again, it may be convenient that this be so, and that
the magnets fit snuggly
in place. The associated magnetic members may be indicated as 84, 86, 88, 90,
92 and 94.
These accommodations may be separated by spacers, indicated generically as
separators or
spacers 96. Spacers 96 may have the form of standoffs, which may themselves be
partitions 98,
and which may include one or more breadth-wise partitions 100, and one of more
depth-wise
partitions 102. All of these partitions 98 taken together, however few or many
there may be,
may be termed a spider or a matrix, be it a separator matrix, or a partition
matrix 104. It is not
necessary that any of partitions 98, or any portion of matrix 104 be formed as
part of, or even be
in contact with peripheral wall 66. However, it may be convenient that they be
formed as a
single monolithic, integrally formed member.
CA 02708325 2010-06-22
11
The use of multiple chambers, and multiple magnetic members 70 may permit pad
assembly 50 to flex to an extent that it might not otherwise be able to do to
conform to, or seat
upon the underlying chute or trough structure. In the case of a reconditioned
trough, it may
thereby facilitate formation of a seal against the trough structure by the
footprint of the pad
assembly, as may discourage leaking. Further, by accommodating a measure of
flexing, the
matrix may tend to prevent or to reduce the tendency toward cracking of the
magnetic members.
Magnetic members 70 may be made of a magnetic material, be it a magnetized
ferromagnetic or nickel material, be it a rare earth magnet material, or be it
a ceramic or ceramic
composite magnetic material. Many such materials are known. In terms of
physical properties
the magnetic material may have a density of the order of 7850 kg/m3 (or 0.283
lb/cu.in.), and a
Young's modulus of 30,000,000 psi. This is very much higher than the materials
of which body
60 may be made, which may have densities in the order of 900 -1100 kg/m3 (0.04
lb/cu.in) and
Young's moduli of the order of 1500 - 15 000 psi for rubber, or 300,000 -
500,000 psi for nylon,
for example. As such the density of the magnetic materials is very much higher
(roughly an
order of magnitude, i.e., approaching 10 times, or perhaps somewhat more than
ten times,
greater), and the flexibility of those materials is very much less than (two
or three orders of
magnitude or more, i.e., of the order of a hundred or a thousand, or more,
times, less than), the
materials of body 62 in which they are encased. Thus, in this specification,
body 62 is flexible
as compared to the materials metallic or metallic-composite materials of
magnetic members 70,
such that if twisted or pressed, body 62 may stretch or twist or deform rather
than magnetic
members 70, and the term "flexible" may be understood in that context, and of
which a non-
limiting example is the relative flexibility of car or truck tires, or solid
fork-lift tires to, those
magnetic materials.
Magnetic members 70 need not themselves necessarily be magnetized. That is,
magnetic
members 70 and the underlying trough structure are magnetically attracted. One
or the other, or
both, are magnetic in use. Typically magnetic members 70 are magnetic.
However, it is
possible that the trough structure itself may be magnetized, or may include
magnetized members,
and it is sufficient that members 70 merely be made of a magnetically
attractive material,
susceptible to magnetic attraction.
Where magnetic member 70 is magnetized, one pole of magnetic member 70 faces
toward first portion 62, and the other pole faces toward second portion 64. It
does not matter
which pole, North or South faces toward or away from trough structure 22
provided that all of
magnetic members 70 face in the same direction.
CA 02708325 2010-06-22
12
The lateral spacing of magnetic members 70 from each other is desirable to the
extent
that they may be mutually repulsive. If adjacent magnetic members 70 are
placed too close
together, their mutual repulsion may tend to cause unwanted out-of-plane
deflection in pad
assembly 50. As such the thickness of the elements of matrix 104 may be of
roughly the same
magnitude as the sideways through-thickness of peripheral wall 66, which may,
for example, be
of the order of 1 - 2 cm, (3/8 - 3/4 inch) or thereabout.
First portion 62 may be made of a first material. In contrast to previous
metal wear
plates, first portion 62 may have a non-metallic surface and body. That
material may be a rubber
or synthetic rubber based material, or may be a UHMW material, or a nylon or a
polypropylene,
or other material such as may, in some embodiments, be suitable for use in
food processing
applications. In the case of rubber or other materials it may include one or
more layers of an
embedded woven fabric. It is intended that the material of first portion 62 be
substantially more
flexible than the magnetic materials 70. It is also intended that the first
material be a consumable
material that may be worn away over time. In the example of a consumable
material for use in
transporting rock ores, the material may approximate the hard-rubber texture
and flexibility of a
truck or car tire. That is, the hardness of the material, and its elasticity,
may fall in generally the
same ranges as that for automotive or solid rubber tires, corresponding to
perhaps 30 - 100
Shore A hardness, or 7 - 50 Shore D hardness. The type of material to be used,
and the level of
suitable elasticity and hardness may vary from application to application. In
any case, the
hardness and elasticity of first portion 62 are substantially different from
that of magnetic
members 70. The elasticity may be suitable for absorbing impact energy, to
some extent. The
first material of first portion 62 may be magnetically non-participating, or
magnetically
transparent. The through thickness t62 of first portion 62 may depend on the
application.
Second portion 64 may be made from a second material. That second material may
be a
rubber or synthetic rubber, or rubber based material, or may be an UHMW
material, or a nylon,
or a polypropylene or polyurethane, depending on the application. Again, if
the application is a
food processing application, or one in which chemical contamination is to be
avoided, the
material of second portion 64 may be selected accordingly. The second material
is intended to
be magnetically transparent, i.e., it is non-participating in a magnetic
sense. The second material
may also tend to be flexible, and may be compressible, as may be suitable for
forming a seal
against the underlying trough structure material such as may tend to
discourage the leakage of
water or other liquids through un-blocked fastener apertures or fittings such
as may remain in the
underlying structure. The types of materials, and ranges of elasticity and
Young's modulus
CA 02708325 2010-06-22
13
discuss above or in the context of the first material may also apply to the
second material. The
through thickness t64 of second portion 64 may be chosen to maintain a roughly
constant stand-
off distance between an adjacent panel of trough 20 and magnetic members 70,
and to maintain
magnetic members 70 (or at least the flat or contoured bottom surfaces
thereof) in a substantially
parallel orientation relative to surface 40 of bottom panel 30 in use.
The third portion, namely peripheral wall 66, may likewise be made of any of
the
materials suitable for the first or second materials. It may be that the
first, second and third
materials are all the same material, or substantially the same material,
although they need not
necessarily be.
The through thicknesses of the various members differ, such that while the
assembly may
have a measure of symmetry in the x and y directions when viewed from above,
the assembly
does not have symmetry in the z direction (i.e., above and below any plane to
which the z-axis is
normal). The through thickness t62 of first portion 62 may be of a roughly
comparable general
magnitude as the through thickness of magnetic members 70, whereas the through-
thickness of
second portion 64 may be very much less, and may be expected to be an order of
magnitude less
than the thickness of magnetic member 70 (and, therefore also an order of
magnitude less than
t62). For example, depending on the application, the through thickness of
magnetic members 70
may be in the range of perhaps as little as 3/8 inches (1 cm), or even '/4" in
some embodiments
such as light or lighter duty embodiments, to perhaps as much as 2" (5 cm).
Common sizes
might be approximately half an inch thick and approximately an inch thick.
First portion 62 may
have a suitable corresponding thickness, be it'/2" inch thick, %" thick, an
inch thick 1-'/2 inches
or 2 inches thick, or possibly thicker. Again the thickness may vary according
to the application
and the material used in that application. In any case'/2 and 1 inch
thicknesses might be typical
thicknesses used for either magnetic member 70 or first portion 62, and it
might not be atypical
for magnetic member 70 and first portion 62 to be of roughly the same or
similar thickness such
that a ratio of t62:t70 might typically lie in the range of 2/5 to 5/2, and
might be about 1:1.
By contrast, second portion 64 may be substantially thinner than either first
portion 62 or
magnetic members 70. For example, second portion 64 may be 1/8" thickness, or
1/16" in
thickness, or less. In one embodiment it may be about 1/32" thickness, and so
therefore an order
of magnitude less than the thickness of either magnetic members 70 or first
portion 62. The
optimum thickness may vary from application to application. In each case
however, the thicker
side of the encapsulating casing is the side that faces toward the workflow of
material, and the
thinner side faces toward trough structure 22.
CA 02708325 2010-06-22
14
The context and use of pad assembly 50 may be understood in terms of overall
size and
weight. While it may be as small as 3" x 3" x 1 ", it may typically have a
total size in the order of
8" x 8" to 30 - 36" x 30 - 36" in surface area by perhaps'/4 to an inch to 2 -
2 1/2 inches or even
3 inches in thickness, giving a weight between about 20 lbs (approx 10 kg) and
100 Lbs (about
50 kg), tending to be closer to 50 lbs, or less such that they are portable by
a single person, and
may be installed or removed by a single person. For larger, heavier assemblies
beyond about
100 lbs, installation and removal may be by machine. One size may be about 12"
x 12" x 2"
overall and 20 - 30 lbs. Pad assemblies 50 are of substantial size, and are
intended for industrial
use. They are large enough to cover a significant area, but may tend not to be
so large or heavy
as to prevent installation and removal by hand. Larger assemblies may be
installed by, or with
the aid of, machinery.
Pad assembly 50 may be manufactured in a mold. Second portion 64 may be laid
in the
mold first, against a flat bottom panel of the mold. This may tend to maintain
second portion 64
flat (or, more generically, conforming to the desired surface contour of the
bottom panel of the
mold, which may in some, or many, embodiments be flat). Peripheral wall 66 may
be placed in
the mold, as may separator matrix 104. The various magnetic members 70 may be
placed in
their associated accommodations. First portion 62 may then be placed in the
mold, and the mold
may be closed. To the extent that each of first portion 62, second portion 64
and peripheral wall
66 is in the form of a "green", or uncured, polymeric material, such as
uncured rubber. The
material may then be heated and cured in the mold, at which time the material
of the various
portions may fuse or cross-link, or vulcanize in the case of rubber based
materials. The resulting
assembly includes encapsulated magnetic material, with the cured polymer then
constituting an
encapsulant. In the normal course the magnetic materials may be fully
surrounded by, and
hermetically sealed within, the encapsulant. This need not necessarily be the
case. Second
portion 64 may have the form of a grid or matrix or grating, or perforated
panel or skin that,
nonetheless, functions as a standoff to maintain the appropriate spacing
distance of magnetic
members 70 from the underlying trough panel, be it 30, 32 or 34.
Alternatively, after placing second portion 64 in the mold, and after
positioning magnetic
members 70 in the mold in the manner of cores or inserts, the remaining
material of body 22
may be injection moulded. In a further alternative, the various components may
be assembled
and attached with suitable bonding agents. Typically pad assembly 50 may be
entirely black in
colour, and to the extent that the predominant material is rubber or rubber
based, carbon black
may be added. The use of a polymer, such as rubber, in this application may
also tend to provide
CA 02708325 2010-06-22
a damping, or absorbing effect both with respect to physical impact and with
respect to noise.
That is, the materials of pad assembly 50 noted above may each tend to have
high anelasticity as
compared to metals such as the steel wear plates previously used - they are
sound deadeners, not
amplifyers.
5
Typically, in use the magnetic material may become visible when the pad is
worn
through, or an operator may make periodic measurements with a gauge to
determine the extent
of wear and whether replacement is required. In alternate embodiments, pad
assembly 50 may
include a wear indicator encapsulated within the assembly, whether a layer or
material plugs of a
10 different (i.e., bright and contrasting) colour or some other means.
In a further alternate embodiment, the underside of second portion 62 may have
a groove
or seat formed therein to accommodate one or more compressible O-rings 120.
The groove may
extend about the peripheral margins of second portion 62, and the O-ring
seated therein may
15 define a footprint, such as might otherwise be defined by the contact area
of the surface of
second portion 62 bearing against the underlying structure. The compression of
the seal may
then determine the stand-off distance. Alternatively, a protruding bead 122
may extend
peripherally about second portion 62, bead 122 being somewhat compressible to
yield a seal.
Where such a bead or O-ring, or the like, is employed to yield a seal, the
larger, cross-wise and
breadth-wise extending portions of second portion 62 may tend nonetheless to
define a minimum
standoff distance between magnetic member 70 and the underlying trough or
other structure,
whatever the compression of the seal or bead may be, and whatever the
deflection of the
peripheral margin of first portion 62 may be. The bead or seal need not be
under, or only under,
the peripheral margin of item 62. There could be more than one such bead or
seal, and a separate
bead or seal might be placed under each individual magnetic member, as may be.
In a still further alternate embodiment, a pad assembly 150 may be provided
with an
array of accommodations 170, being individually accommodations 172, 174, 176,
178, 180, and
182. As can be seen, these accommodations are arranged about the peripheral
margin of pad
assembly 150, the more central region 184 being left without magnetic
elements. In using this
peripheral array, the outside edge of pad assembly 150 is held in place.
In use, trough structure 22 is lined with an array of tiles such as pad
members 50 as
described. The tiles do not need to be perfectly tightly positioned against
each other, although it
may be desirable. To the extent that the workflow material may include
"fines", those fine
materials will, soon after installation, tend to fill any remaining
interstitial cracks. The weight of
CA 02708325 2010-06-22
16
pad assembly 50; the magnetic force between pad assembly 50 and trough
structure 20; and the
closely adjacent presence of other pad assemblies 50 preventing lateral
movement or migration,
may all tend to work to retain each pad 50 in its desired place. The magnetic
force, alone, may
tend to hold pad assembly 50 in place.
Over time, the impact of falling or bouncing workflow materials on the various
tiles, and
the passage of the workflow particulate over the tiles may tend to abrade and
then wear away the
sacrificial or consumable material of first portion 62. Subject to appropriate
periodic
monitoring, at some time the wear on at least some tiles will have reached the
point where
replacement is required. At that point maintenance workers with hand pries not
unlike un-
sharpened'/4" or 1" chisels, may progressively pry up and remove tiles,
working inward from an
edge (typically an uppermost edge) of array 40 toward those tiles to be
removed. In other
circumstances, pad assembly 50 may be removed, such as in an automated
process, by the use of
magnets developing a stronger magnetic force than that attracting pad assembly
50 to the
underlying substrate, that stronger magnetic force possibly being that of an
electromagnet on a
removal tool or boom.
In contrast to previous monolithic hardened steel wear plates, only those of
pad
assemblies 50 that are worn need be replaced by exchanging them for new tiles.
Furthermore,
and alternatively, to the extent that a single size of tile is used, or a
small number of sizes and
shapes of tiles are used, it may be that worn tiles taken from near the
longitudinal centerline of
trough 20 may be exchanged with less-worn tiles from, for example, the upper
edges of the
flanks of trough 20 to promote more even wear prior to a need for replacement.
Pad assembly 50 may tend to provide an abrasion and impact resistant surface
to
industrial equipment. In the view of the inventor it is quite dissimilar from
known alternatives.
While there are products that use magnetic force to attract, for example, iron
particles from an
ore mix to yield an "iron" wear surface, these magnets are installed
mechanically and their
purpose is not to hold the wear members in place but rather to attract the
iron particles. Various
embodiments shown and described herein provide wear liners that "fasten" to
the underlying
structure using magnetic force alone. Those pads tend to remain in place under
the influence of
magnetic force while being subjected to impact and abrasion.
The embodiments above include embodiments in which the seating of the
footprint of the
wear pad may tend to create a water resistant seal on the face of the surface
of the underlying
equipment. The pads permit small areas of worn pads, or even a single worn
pad, to be
CA 02708325 2010-06-22
17
exchanged out without removing the whole lining, or substantially the whole
lining. As
illustrated in Figure Id, for example, the wear pads can be made to suit a
variety of geometric
requirements. As indicated, the pads may be made to a multitude of different
thicknesses. The
pads are not intended to, nor do they, rely on direct contact between the
magnetic members and
Underlying ferromagnetic materials, and they are not intended to be used, as
"patches" for
existing metal surfaces. Nor are the pad assemblies used as anchor fittings
for holding other
ferrous metal wear members in place. Rather, various embodiments illustrated
and described
herein are stand alone units.
Several embodiments of wear pad members have been described and illustrated.
For
brevity of description it may be understood that the features of those various
embodiments may
be "mixed and matched" in many different permutations and combinations,
without each specific
combination being described and illustrated individually herein.
The principles of the present invention are not limited to these specific
examples, which
are given by way of illustration. It is possible to make other embodiments
that employ the
principles of the invention and that fall within its spirit and scope of the
invention. Since
changes in and or additions to the above-described embodiments may be made
without departing
from the nature, spirit or scope of the invention, the invention is not to be
limited to those details,
but only by the appended claims.
