CA2914893A1 - Impact hammers - Google Patents

Abstract

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; and 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 wear protection and impact resistance.

Description

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 WS Legal% 053707 \00008'µ 12453839v 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 WSLega1\053707\00008\12453839v1 2 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.
WSLegal\ 053707 \ 00008 \ 12453839v1 3

[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 WSLega1\053707 \00008 124538390 4 =
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'.
WSLegal 053707\00008\1245383M 5 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 WSLegal\ 053707 \ 000081124538390 6 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 WSLegah 053707 \ 00008 \12453839v1 7 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 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 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.
WSL ega1,053707 00008 2451819µ1 8

Claims (9)

CLAIMS:

1. A wear resistant impact hammer, 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; and 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 wear protection and impact resistance.

2. The impact hammer as claimed in claim 1, wherein the body block is manufactured as a single unit that is cast or forged from carbon steel, low allow steel or stainless steel.

3. The impact hammer as claimed in claim 1, wherein the wear resistant tiles or inserts are made from a hard material comprising sintered tungsten carbide, ceramics, cermets, or polycrystalline diamond.

4. The impact hammer as claimed in claim 1, wherein the wear resistant tiles or inserts are attached to the front face and top face by a brazing material.

5. The impact hammer as claimed in claim 1, wherein the brazing material comprises brazing alloys, silver, gold, copper, nickel or tri-braze.

6. The impact hammer as claimed in claim 1, wherein the wear resistant tiles are attached to the front face and top face by metallurgical attachment such as welding, diffusion bonding or hot isostatic pressing.

7. The impact hammer as claimed in claim 1, wherein the wear resistant tiles or inserts are attached to the front face and top face by a bonding material.

8. The impact hammer as claimed in claim 1, wherein the wear resistant tiles or inserts are mechanically attached.

9. The impact hammer as claimed in claim 1, wherein the wear resistant tiles or inserts are cast in place by infiltration casting.