Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02914893 2015-12-07
PATENT APPLICATION
DOCKET NO.: NS-548
IMPACT HAMMERS
INVENTORS:
OBAIA, Khaled, TIEU, John, MACNEIL, Daniel, CHIOVELLI,
Stefano
ASSIGNEE:
SYNCRUDE CANADA LTD. In Trust for the Owners of the
Syncrude Project
Field of the invention
[0001]
The present application relates generally to rotary impact crushers
and, more particularly, to impact hammers of rotary impact crushers having
wear
resistant impact surfaces.
Background of the invention
[0002]
Rotary impact crushers are often used for breaking large pieces of
rock-like substances into smaller fragments. For example, rotary impact
crushers have
been used to crush coal lumps and oversize rock for easier conveying.
Generally,
rotary impact crushers comprise a plurality of impact hammers located in a
milling
chamber. The impact hammers are typically attached to a rotor assembly and may
either be fixedly attached or free-swinging.
[0003]
Rotary impact crushers have also been used in the oil sands mining
industry for crushing mined oil sand lumps and rocks. However, oil sand is a
very
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abrasive material and, hence, due to the impact and/or abrasive nature of oil
sand, the
impact hammers wear fairly quickly, resulting in costly downtime of the rotary
impact
crushers for maintenance.
[0004] Accordingly, there is a need for improved impact hammers having
better wear resistance and impact resistance for increased life.
Summary of the invention
[0005] The current application is directed to impact hammers for use
in rotary
impact crushers. More particularly, impact hammers of the present invention
comprise
wear resistant tiles or inserts, which are sized and shaped to provide a hard
impact
surface for extreme wear protection as well as providing an energy absorbing
mass for
extreme impact resistance.
[0006] In order to determine the size, shape, arrangement and
attachment
means of the wear resistant tiles or inserts, one or more of the following
criteria may be
used:
1. The impact load acting on the hammer heads when in operation;
2. The residual stresses resulting from a particular means for attaching the
wear
resistant tiles to the hammer head (also referred to as "fabrication
stresses");
3. The manufacturing technique used to manufacture the impact hammer and the
limitations thereof; and
4. The actual wear profile of hammer heads as measured in the field.
[0007] More particularly, the wear profile or pattern on existing
impact
hammers which do not have wear resistant tiles or inserts can be used to
determine the
surface area that receives the most impact, thus determining the surface area
that
needs to be covered. Further, impact loading will help to determine the
minimum
thickness of the wear resistant tiles or insert necessary to minimize spalling
or breaking.
The practical maximum thickness can also be determined. The length and width
of the
tiles or inserts are determined based on manufacturing constraints and
residual
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stresses. In some embodiments, it is more useful to have a plurality of
smaller tiles
rather than a single, large tile or insert. Further, the separation between
tiles or inserts
reduces the impact load on the tiles or inserts. Thus, the wear resistant
tiles or inserts
are sized, shaped and attached to an impact hammer to provide a balance
between
providing a hard surface for wear protection and providing a tough energy
absorbing
mass for impact resistance.
[0008] Broadly stated, in one aspect of the present invention, a wear
resistant
impact hammer is provided comprising:
= a body block having an impact head, said impact head having a front face,
two
side faces, a back face and a top face;
= a plurality of wear resistant tiles or inserts sized and shaped to cover
at least a
portion of the front face and at least a portion of the top face;
whereby the wear resistant tiles or inserts are sized and shaped to provide
both
wear protection and impact resistance.
In one embodiment, the wear resistant tiles or inserts further cover at least
a portion
of one or both side faces.
[0009] In one embodiment, the body block is manufactured as a single
unit
that is cast or forged from carbon steel, low allow steel or stainless steel.
In one
embodiment, the wear resistant tiles or inserts are made from a hard material
comprising sintered tungsten carbide, ceramics, cermets, a metal matrix
composite
(MMC) or polycrystalline diamond. In one embodiment, the wear resistant tiles
or
inserts are attached to the front face and top face by a brazing material. In
one
embodiment, the brazing material comprises brazing alloys, silver, gold,
copper, nickel
or tri-braze. In one embodiment, the wear resistant tiles are attached to the
front face
and top face by metallurgical attachment such as welding or hot isostatic
pressing. In
one embodiment, the wear resistant tiles or inserts are attached to the front
face and
top face by a bonding material. In one embodiment, the wear resistant tiles or
inserts
are mechanically attached.
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[00010] Additional aspects and advantages of the present invention will
be
apparent in view of the description, which follows. It should be understood,
however,
that the detailed description and the specific examples, while indicating
preferred
embodiments of the invention, are given by way of illustration only, since
various
changes and modifications will become apparent to those skilled in the art
from this
detailed description.
Brief Description of the Drawings
[00011] FIG. 1 is a cross-sectional diagram of a rotary impact crusher
having a
plurality of impact hammers.
[00012] FIG. 2A is a front view of one embodiment of an impact hammer.
[00013] FIG. 2B is a side view of the impact hammer of FIG. 2.
[00014] FIG. 3A is a perspective view of another embodiment of an
impact
hammer.
[00015] FIG. 3B is a front view of the impact hammer of FIG. 3A.
[00016] FIG. 30 is a side view of the impact hammer of FIG. 3A.
[00017] FIG. 4 is a side view of another embodiment of an impact
hammer.
[00018] FIG. 5 is a side view of another embodiment of an impact
hammer.
[00019] FIG. 6A is a front view of another embodiment of an impact
hammer.
[00020] FIG. 6B is a side view of the impact hammer of FIG. 6A.
Detailed Description of Preferred Embodiments
[00021] The detailed description set forth below in connection with the
appended drawings is intended as a description of various embodiments of the
present
application and is not intended to represent the only embodiments
contemplated. The
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=
detailed description includes specific details for the purpose of providing a
comprehensive understanding of the present application. However, it will be
apparent to
those skilled in the art that the present application may be practised without
these
specific details.
[00022] The present application relates generally to rotary impact
crushers
and, more particularly, to impact hammers of rotary impact crushers having
wear
resistant impact surfaces. An embodiment of an exemplary rotary impact crusher
is
shown in FIG. 1. Impact crusher 50 comprises an inlet 52 for receiving the
feed to be
crushed such as oil sand ore. Impact crusher 50 further comprises at least one
breaker
(impact) plate 54, which can be adjustable by means of setting device 58 as
shown in
FIG. 1. The orientation, geometry and angle of the impact surface influences
the size
and distribution of the aggregate produced.
[00023] Impact crusher 50 further comprises a rotor 56 having at least
one
impact hammer 10 attached around its periphery. As shown in FIG. 1, impact
hammers
are swinging hammers, which swing relative to their pivot points 19. Thus,
when the
rotor 56 rotates, the impact hammers 10 will strike the feed as it travels
down the
breaker plates to reduce the feed size as desired. It is understood, however,
that the
impact hammers may also be fixedly attached to the rotor by methods well known
in the
art. In accordance with the present application, some or all of the impact
hammers 10
may have wear resistant impact surfaces, as will be described in more detail
below.
[00024] With reference now to FIGS. 2A and 2B, FIG. 2A is a front view
of an
impact hammer of the present application and FIG. 2B is a side view of the
impact
hammer in FIG. 2A. In this embodiment, impact hammer 110 comprises a body
block
113 which may be manufactured as a single unit and is preferably cast or
forged from a
carbon steel, stainless steel, low alloy steel, or other material with
suitable properties,
e.g., strength and toughness after processing. Body block 113 comprises a
mounting
post 112 having a tapered neck 114 and an impact head 116. As can be seen more
clearly in FIG. 2B, impact head 116 has a sloped or angled front face 130, a
substantially vertical back face 136, and two substantially vertical side
faces 132, 132'.
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The top face 134 is substantially horizontal. The bottom 120 of the mounting
post 112
may be circular in shape having a hole 122 bored therethrough for attachment
to the
rotor 56 shown in FIG. 1 and to allow the impact hammer 110 to swing.
[00025] Attached to the sloped front face 130 of impact head 116 are a
plurality
of wear resistant tiles 118 which can be made from a hard material such as
sintered
tungsten carbide, ceramics, cermets, polycrystalline diamond and the like. The
wear
resistant tiles 118 are sized and shaped such that the impact head is now
essentially
squared off. In this embodiment, the outer surfaces of wear resistant tiles
118 are
pyramidal in shape, so that the tips of the pyramids protrude outwardly to
provide even
more wear protection from rocks and the like. Without being bound to theory,
it is
believed that the geometry of the tiles may help the tungsten carbide, etc. to
absorb the
impact energy. Further, having protruding tips may help break lumps, rocks,
etc. while
still reducing the impact on the tungsten carbide, etc. tiles. It can also be
seen in FIG.
2B that additional wear resistant tiles 118' are attached to the top face 134
of impact
head 116. Thus, essentially all of the direct and indirect impact areas of
impact head
116 will be protected with wear resistant tiles.
[00026] In one embodiment, the wear resistant tiles 118, 118' can be
attached
to the front face 130 and the top face 134 of the impact head 116 by a brazing
material
known in the art such as brazing alloys, silver, gold, copper, nickel, tri-
braze, etc. An
example of tri-braze would be copper sandwiched between two silver layers. In
another
embodiment, the wear resistant tiles 118, 118' are bonded to the front face
130 and top
face 134 by a bonding material such as an epoxy adhesive. In another
embodiment,
the wear resistant tiles 118, 118' can be mechanically attached to the impact
head 116
by means of bolts, dovetails, and the like. In another embodiment, the tiles
can be
metallurgically attached by welding hot isostatic pressing, etc.
[00027] The wear resistant tiles 118, 118' are of a size and shape to
provide
coverage of the most wear-prone regions of the impact hammer 110 and, thus,
improved wear resistance. In the embodiment shown in FIGS. 2A and 2B, the
tiles are
between about 1/4 inch to about 2 inches thick. It is understood that the
length, width
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and depth of the wear resistant tiles are influence by physical dimensions of
the
hammer 160 and the impact loading generated by the impact hammer. As mentioned
above, in this particular embodiment, the tiles are pyramidal in shape to
provide optimal
wear resistance and impact resistance. The tiles are also spaced apart so that
they can
deform under impact. If the tiles are constrained, they may crack more
readily. Thus, in
this embodiment, the tiles are very strong in compression and weak in tension.
(000281 FIG. 3A is a perspective view of another embodiment of an
impact
hammer 210 of the present application, FIG. 3B is a front view of impact
hammer 210
and FIG. 3C is a side view of impact hammer 210. In this embodiment, impact
hammer
210 comprises a body block 213 which may be manufactured as a single unit and
is
preferably cast or forged from a carbon steel, stainless steel, low alloy
steel, or other
material with suitable properties, e.g., strength and toughness after
processing. Body
block 213 comprises a mounting post 212 having a tapered neck 214 and an
impact
head 216. Mounting post 212 may further comprise hole 222 for attachment. In
this
embodiment, a plurality of wear resistant tiles 218, which can be made from a
hard
material such as sintered tungsten carbide, ceramics, cermets, polycrystalline
diamond
and the like, are first affixed (e.g., welded, glued (epoxy), brazed, etc.) to
a substrate
230 such as chrome white iron, carbon steel, stainless steel, low alloy steel
or other
material with suitable properties, e.g., strength and toughness after
processing. Thus,
the wear resistant tiles 218 do not need to be attached directly to impact
head 216 of
body block 213.
[00029] In some instances, when wear resistant tiles are directly
brazed to an
impact head of a body block, or when hot isostatic pressing (HIP) is used, it
may affect
the properties of the entirety of the body block. Brazing and HIP must be
performed at
very high temperatures and, thus, the entire body block may need to be heated.
This
may compromise the integrity of the body block. However, because substrate 230
is
generally made from weldable-grade steel, carbon steel low alloy steel and the
like, the
wear resistant tiles 218 can be first attached to the substrate 230. Then,
substrate 230
having wear resistant tiles 218 attached thereto can be welded to the impact
head 216
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of body block 213. Thus, the integrity of the body block 213 will not be
compromised by
thermal processing during tile attachment.
[00030] In some instances, it may be desirable to bolt a substrate
having wear
resistant tiles to the head of the impact hammer. FIG. 4 illustrates substrate
330 having
wear resistant tiles 318 attached at one end of substrate 330 and a mounting
post 332
attached at the opposite end of substrate 330. The impact head 316 of impact
hammer
310 has a bolt 334 imbedded therein and a cavity 340 machined therein for
receiving
the mounting post 332. The mounting post 322 is adapted to attach to bolt 334.
[00031] FIG. 5 illustrates another embodiment where substrate 430 has
wear
resistant tiles 418 attached at one end and is dove-tailed at the other end.
The dovetail
436 can be inserted into a matching cavity 440, which has been machined into
impact
head 416 and secured by welding. Optionally, a bolt 438 can be used to secure
dovetail 436 in cavity 440. In the alternative, dovetail 436 can simply be
welded into
cavity 440.
[00032] In one embodiment, shown in FIGS. 6A and 6B, the impact head
616
of the impact hammer 610 can machined or milled to include a plurality of
cavities 640
for inserting wear resistant tiles/plugs 618 therein. The tiles/plugs 618 can
be any
shape, for example, square or rectangular. The wear resistant plugs are of a
size and
shape to provide coverage of the most wear-prone regions of the impact hammer
612
and, thus, improved wear resistance. The tiles/plugs can be secured in the
cavities 640
by brazing, welding, epoxy, diffusion bonding, etc. or can be cast in place by
infiltration
casting. In this embodiment, the tiles/plugs are constrained, taking advantage
of the
high compressive strength of tungsten carbide, and, hence, are strong in
compression
but weak in tension.
[00033] The scope of the claims should not be limited by the preferred
embodiments set forth in the examples, but should be given the broadest
interpretation
consistent with the description as a whole.
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