U.S. patent application number 13/382917 was filed with the patent office on 2012-06-14 for attack tool assembly.
This patent application is currently assigned to Element Six Holding GMBH. Invention is credited to Gerald Francis Flynn, Karl-Georg Hildebrand, Frank Friedrich Lachmann.
Application Number | 20120146390 13/382917 |
Document ID | / |
Family ID | 41022476 |
Filed Date | 2012-06-14 |
United States Patent
Application |
20120146390 |
Kind Code |
A1 |
Flynn; Gerald Francis ; et
al. |
June 14, 2012 |
ATTACK TOOL ASSEMBLY
Abstract
An attack tool assembly (10) comprising an attack tool having a
shank (23) extending therefrom, the shank (23) having a
longitudinal axis; and a holder having a holder body (31) and a
bore for receiving the shank (23) of the attack tool (10); the
holder being adapted to receive the shank (23) in a configuration
in which it prevents the shank (23) from rotating relative to the
bore when the holder is in an engaged condition, and in which it
allows the shank (23) to be rotatable relative to the bore when the
holder is in a disengaged condition, so as to enable the shank (23)
to be selectively securable to the holder in a required orientation
about the longitudinal axis. The attack tool assembly (10) is
particularly but not exclusively for use in the degradation of rock
or asphalt bodies for formations, such as in soft rock mining and
asphalt milling.
Inventors: |
Flynn; Gerald Francis;
(Ascot, GB) ; Hildebrand; Karl-Georg; (Burghaun,
DE) ; Lachmann; Frank Friedrich; (Burghaun,
DE) |
Assignee: |
Element Six Holding GMBH
Burghaun
DE
|
Family ID: |
41022476 |
Appl. No.: |
13/382917 |
Filed: |
July 12, 2010 |
PCT Filed: |
July 12, 2010 |
PCT NO: |
PCT/EP10/59991 |
371 Date: |
March 1, 2012 |
Current U.S.
Class: |
299/79.1 |
Current CPC
Class: |
E21C 35/19 20130101;
E21C 35/183 20130101 |
Class at
Publication: |
299/79.1 |
International
Class: |
E21C 35/19 20060101
E21C035/19 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 10, 2009 |
GB |
0912022.1 |
Claims
1. An attack tool assembly comprising an attack tool having a shank
extending therefrom, the shank having a longitudinal axis; and a
holder having a bore for receiving the shank of the attack tool;
the holder being adapted to receive the shank in a configuration in
which it prevents the shank from rotating relative to the bore when
the holder is in an engaged condition, and in which it allows the
shank to be rotatable relative to the bore when the holder is in a
disengaged condition, so as to enable the shank to be selectively
securable to the holder in a required orientation about the
longitudinal axis.
2. The attack tool assembly according to claim 1, in which the
holder includes engagement means for securing the shank relative to
the holder, the engagement means engaging the shank when the holder
is in an engaged condition, and being spaced apart from the shank
when the holder is in a disengaged condition.
3. The attack tool assembly according to claim 1, in which the bore
engages the shank when the attack tool assembly is in the engaged
condition, and wherein the disengaged condition is achievable by
heating the holder.
4. The attack tool assembly as claimed in claim 1, in which at
least part of the shank is cylindrical or frustoconical in
shape.
5. The attack tool assembly as claimed in claim 1, in which the
attack tool comprises a superhard tip joined to a cemented carbide
support body.
6. The attack tool assembly as claimed in claim 1, in which the
attack tool comprises a polycrystalline diamond structure bonded to
a cemented carbide substrate.
7. The attack tool assembly as claimed in claim 1, in which the
engagement means is in the form of a protrusion that protrudes into
the bore, the protrusion being displaceable between an engaged
position in which an end of the protrusion abuts the shank, and a
retracted position, in which the end of the protrusion is spaced
apart from the shank.
8. The attack tool assembly according to claim 7 wherein the
protrusion is in the form of a threaded rod extending through a
threaded aperture provided in the holder.
9. The attack tool assembly according to claim 1, in which the
shank includes an engagement zone that is not cylindrically
rotationally symmetric, the engagement zone in use being at least
partially aligned with the threaded aperture in the holder.
10. The attack tool assembly according to claim 9, in which the
engagement zone includes a plurality of substantially planar
surfaces located about a periphery of the shank, in order for the
protrusion in use to abut a selected planar surface when in the
engaged position.
11. The attack tool assembly as claimed in claim 1, comprising an
attack tool and a holder configured such that the attack tool is
continuously indexable within the holder.
12. A method of releasing an attack tool from a steel holder of an
attack tool assembly the method including the step of heating the
steel holder to expand the bore.
13. A method of using an attack tool assembly as claimed in claim
1, the method including using the attack tool assembly to degrade a
body, putting the holder into the disengaged condition to release
the attack tool, reorienting the attack tool within the holder;
putting the holder into the engaged condition; and further using
the attack tool assembly to degrade a body.
Description
FIELD
[0001] This invention relates to an attack tool assembly, and more
particularly, but not exclusively, to an attack tool assembly
having a superhard working tip for use in the degradation of rock
and asphalt bodies or formations, such as in soft rock mining and
asphalt milling.
BACKGROUND
[0002] In this specification an attack tool assembly shall be
interpreted to mean a high impact resistant and high wear resistant
tool that may be used in milling, mining, degradation and
excavation applications. As used herein, a pick tool is an attack
tool assembly in assembled form. The attack tool assembly may
comprise an attack tool and holder, the attack tool comprising a
working tip at one end and a shank at an opposite end, the holder
being adapted to receive the shank of the attack tool and to hold
it by mechanical means. In some applications, for example road
reconditioning, a plurality of pick tools may be mounted on a
rotatable drum and driven against the body to be degraded as the
drum is rotated against the body.
[0003] In some pick tools, the attack tools are capable of rotating
about their own axis in use ("rotating" tools), and in other pick
tools ("non-rotating" or "fixed" tools) they are held in a fixed
orientation relative to their holders. The non-rotating tool design
is the more widely used design used in conjunction with hard-metal
tips.
[0004] The entire pick tool including the working tip may be made
from a hard metal, such as cemented tungsten carbide, or the
working tip may comprise a superhard material. Superhard materials
have Vickers hardness of greater than about 25 GPa and include
composite materials that incorporate diamond or cubic boron
nitride. In polycrystalline diamond (PCD) material is an example of
a superhard material. PCD material comprises a mass of
substantially inter-grown diamond grains forming a skeletal mass
defining interstices between the diamond grains. PCD material may
comprise at least about 80 volume % diamond and may be made by
subjecting an aggregated mass of diamond grains to an ultra-high
pressure of greater than about 5 GPa, for example, and a
temperature of at least about 1,200 degrees centigrade, for
example. While PCD is much more abrasion resistant than
hard-metals, its strength and impact resistance are generally much
lower. Since rock degradation may be a high impact process, PCD has
not yet become commercially significant in mining or asphalt
processing applications, although recent advances in PCD tool
design have shown potential to extend substantially the working
life of PCD tips in high impact operations. These developments may
increase the use of PCD in attack tool applications. The life of
pick tools comprising a PCD working tip may become determined by
the rate of wear of the other attack tool components and the
support base in particular. For this reason, rotatable tools may be
preferred when using PCD working tips since this allows the tool to
wear more evenly around its central axis, enabling its working life
to be maximised. However, rotating tools may introduce problems
such as jamming, where the rotation becomes prevented or restricted
by fouling of the interface between the tool and holder, or
mechanical distortion. Another serious problem may be the wear of
the shaft and bore surfaces arising from the rotation of the shaft.
U.S. Pat. No. 7,320,505 discloses the use of highly wear resistant
surfaces on the shank and bore to address this problem.
[0005] United States patent application publication number
2008035383 discloses a high impact resistant tool having a
superhard material bonded to a cemented metal carbide substrate,
the cemented metal carbide substrate being bonded to a front end of
a cemented metal carbide segment, which has a stem formed in the
base end, the stem being press fit into a bore of a steel body.
[0006] United States patent application publication number
2008169698 discloses a high impact resistant attack tool comprising
a superhard material bonded to a cemented metal carbide substrate
at a non-planar interface and a stem formed in a base end of a
carbide segment, the carbide stem being press fitted into a bore of
a steel body.
[0007] U.S. Pat. No. 7,396,086 discloses a pick comprising a shank
attached to a base of a steel body, a cemented metal carbide core
press fit into the steel body opposite the shank, and an impact tip
bonded to a first end of the core opposite the shank. The press fit
may comprise an interference of between 1 and 5 thousandths of an
inch proximate the second end of the core.
[0008] U.S. Pat. No. 7,401,863 discloses a pick comprising a shank
attached to a base of a steel body, a cemented metal carbide core
press fit into the steel body opposite the shank, and an impact tip
bonded to a first end of the core opposite the shank. The impact
tip comprises a superhard material. Also disclosed is a method of
reusing a carbide core, the method including removing the used
carbide core from the worn steel body by cutting or grinding away
portions of the steel body of the provided pick, and then press
fitting the used carbide core into a cavity substantially opposite
a shank of a substantially unused steel body of a pick.
[0009] U.S. Pat. No. 7,568,770 discloses a pick comprising a steel
body comprising a formed shank attached to a first end of the body
and generally extending along a central axis of the body. An impact
tip is secured to a second end of the steel body and comprises a
carbide substrate attached to the second end of the steel body
which is bonded to a superhard material. The impact tip may be
brazed to a carbide bolster which is press fit into a bore formed
in the steel body
[0010] There is a need to provide a superhard attack tool assembly
having enhanced working life.
SUMMARY
[0011] According to a first aspect of the invention there is
provided an attack tool assembly comprising an attack tool having a
shank extending therefrom, the shank having a longitudinal axis;
and a holder having a bore for receiving the shank of the attack
tool; the holder being adapted to receive the shank in a
configuration in which it prevents the shank from rotating relative
to the bore when the holder is in an engaged condition, and in
which it allows the shank to be rotatable relative to the bore when
the holder is in a disengaged condition, so as to enable the shank
to be selectively securable to the holder in a required orientation
about the longitudinal axis.
[0012] In one embodiment of the invention, the holder may include
engagement means for securing the shank relative to the holder, the
engagement means engaging the shank when the holder is in an
engaged condition, and being spaced apart from the shank when the
holder is in a disengaged condition.
[0013] In one embodiment of the invention, the engagement means may
be in the form of a protrusion that protrudes into the bore, the
protrusion being displaceable between an engaged position in which
an end of the protrusion abuts the shank, and a retracted position,
in which the end of the protrusion is spaced apart from the
shank.
[0014] In one embodiment of the invention, the protrusion may be in
the form of a threaded rod extending through a threaded aperture
provided in the holder. The threaded rod may be a screw.
[0015] In one embodiment of the invention, the shank may include an
engagement zone that is not cylindrically rotationally symmetric.
In use, the engagement zone may be at least partially aligned with
the threaded aperture in the holder. In one embodiment of the
invention, the engagement zone may include a plurality of
substantially planar surfaces arranged on a periphery of the shank,
to permit the protrusion in use to abut a selected planar surface
when in the engaged position.
[0016] In one embodiment of the invention, at least part of the
shank, or substantially the entire shank may be substantially
cylindrical or frustoconical in shape.
[0017] In one embodiment of the invention, the attack tool assembly
may comprise an attack tool and a holder configured such that the
attack tool is continuously indexable within the holder. In one
embodiment, the attack tool may be infinitely indexable, not being
limited to a predetermined number of orientations.
[0018] In one embodiment of the invention, the bore may engage the
shank when the attack tool assembly is in the engaged condition,
and the disengaged condition may be achievable by heating the
holder, alternatively by cooling the shank.
[0019] In one embodiment of the invention, the attack tool of the
attack tool assembly may include a superhard tip joined to a
cemented carbide support body, and in one embodiment, the superhard
tip may comprise a polycrystalline diamond structure bonded to a
cemented carbide substrate.
[0020] According to an aspect of the invention there is provided a
method of putting the holder in the disengaged condition, the
method including heating the steel holder to expand the bore.
[0021] An aspect of the invention provides a method of using an
embodiment of an attack tool assembly according to the invention,
the method including using the attack tool assembly to degrade a
body, putting the holder into the disengaged condition to release
the attack tool, reorienting the attack tool within the holder;
putting the holder into the engaged condition; and further using
the attack tool assembly to degrade a body.
DRAWINGS
[0022] Non-limiting embodiments will now be described with
reference to the accompanying drawings, of which:
[0023] FIG. 1 is a perspective view of an embodiment of an attack
tool assembly in accordance with the invention;
[0024] FIG. 2 is a side view of the attack tool assembly of FIG.
1;
[0025] FIG. 3 is a perspective view of an attack tool of the attack
tool assembly of FIG. 1;
[0026] FIG. 4 is a perspective view of an embodiment of a holder of
the attack tool assembly of FIG. 1;
[0027] FIG. 5 is a partial cross-sectional side view of a part of
the attack tool assembly of FIG. 1;
[0028] FIG. 6 is a partial cross-sectional side view of the attack
tool of FIG. 3;
[0029] FIG. 7(a) shows a schematic partially cut-away side view of
an embodiment of a pick tool;
[0030] FIG. 7(b) shows a schematic side view of the embodiment of
an attack tool; and
[0031] FIG. 7(c) shows a partially cut-away perspective view side
view of an embodiment of a steel holder.
DETAILED DESCRIPTION OF EMBODIMENTS
[0032] As used herein, "superhard" means a Vickers hardness of at
least 25 GPa.
[0033] As used herein, a superhard tool, insert or component means
a tool, insert or component comprising a superhard material.
[0034] Referring to FIG. 1 to FIG. 6, in which like numerals
indicate like features, a non-limiting example of an embodiment of
an attack tool assembly 10 comprises an attack tool 20, which is
secured to a holder 30 that may be connected to a rotatable drum
(not shown) of an excavation, milling, degradation or mining
machine (not shown). The attack tool 20 comprises a base 22 having
at one end a working tip 21 made from or comprising a superhard
material, and a shank 23 extending from the base at an opposite
end. The shank 23 is an integral part of the attack tool and is
bonded to the support base 22 directly or indirectly via an
intermediate portion. The working tip 21 comprises a superhard
material such as PCD, having extremely high abrasive wear
resistance. The working tip 21 may be mounted onto a supporting
base 22 made of a wear-resistant hard metal such as cemented
tungsten carbide or hard steel, or a ceramic material. The working
tip 21 may be attached to the base 22 by brazing, for example, or
other methods known in the art. While the material of the base 22
may be as wear-resistant as possible, it would be significantly
less wear resistant than the superhard material of the tip 21. For
this reason, the base 22 may tend to wear away in use much more
rapidly than the superhard working tip 21 and may limit the working
life of the attack tool 20. The working tip 21 may have a pointed,
domed or chisel shape, and it may be desirable for the integrity of
the working edge or tip to maintain sharpness in order to cut rock
efficiently.
[0035] An article may be defined as having cylindrical rotational
symmetry if there is an axis passing through it such that the
article appears substantially identical from any given perspective
as it is rotated through 360 degrees about that axis. An article
has less than cylindrical rotational symmetry if this condition
cannot be met. With reference to FIG. 2, a principal, central or
longitudinal axis of the attack tool 20 may be defined as the line
B-B passing through a central point on the tip 21 and the centre of
mass of the attack tool 20. As used herein, the term "shank" is
meant to be construed broadly as being the part of the attack tool
20 adapted to be connectable to the holder 30 directly or via an
intermediate sleeve (not shown), which is adapted to accommodate
the shank 23 and to be capable of holding it. With reference to
FIG. 1 to FIG. 6, an embodiment of an attack tool assembly may
comprise an attack tool 20 and holder 30 adapted so that the tool
20 cannot rotate about its principle axis in use, but it is capable
of being detached from the holder 30 and re-attached at a different
orientation about this axis. Throughout the working life of the
tool 20, it may be possible to re-orientate it manually within the
holder 30 in order to distribute the wear more evenly than would be
possible in conventional non-rotating tool assemblies. The
principal benefit is prolonged working life of the tool while
avoiding problems associated with wear and jamming at the
shank-bore interface.
[0036] With reference to FIG. 2, FIG. 3 and FIG. 4, an embodiment
of a holder 30 comprises a body 31 in which is provided a bore 32
suitable for receiving the shank 23 of the attack tool 20. The
shank 23 of the attack tool 20 may include an engagement zone 24
that has less than cylindrical rotational symmetry about the
principal axis B-B. The reduced symmetry may enable the attack tool
20 to be securely held by the holder 30 so that it cannot rotate
about its central axis. The holder 30 may further comprise a
threaded aperture 33 that extends through the body 31 of the holder
30 into the bore 32. The aperture 33 may be substantially
perpendicular to the bore 32 and to the principal axis B-B of the
tool 20. The threaded aperture 33 may permit an engagement means
(not shown), for example in the form of a threaded screw, to abut a
surface 25 of the shank 23 to effect a clamping action once the
shank 23 is inserted into the holder bore 32, and so to exert a
clamping force on the shank 23 in order to hold it secure in use.
The screw (not shown) may be selectively disengaged from contact
(i.e. by unscrewing it) so as to permit the attack tool shank 23 to
be withdrawn from the holder bore 32, thereby allowing the attack
tool 20 to be re-orientated and re-installed.
[0037] With reference to FIG. 5 and FIG. 6, the engagement zone 24
may comprise a finite, integer number of substantially planar
surfaces 25 that meet at angles of about 90 degrees or greater. The
engagement zone 24 may have four-fold symmetry about the central
tool axis, with a portion of the shank 23 having four substantially
planar outer surface regions 25. The four planar surfaces 25 are
distinct, have substantially the same surface areas and are
positioned intermediate the extreme ends of the shank 23,
approximately equidistant either end. The planar surfaces 25 are
furthermore substantially parallel to the central axis and meet at
four right angles.
[0038] Many variations of shank configuration and shape may be used
to facilitate the prevention of its rotation within the holder,
while permitting the attack tool to be released from the holder and
re-inserted at a limited number of different orientations about the
principal axis. For example, the shank may comprise substantially
planar surface regions that do not meet at right angles, having
arcuate surface portions between them, for example. They may be
positioned at substantially the same or different axial distances
from either end of the tool. It is also not essential that there be
any substantially planar outer surface regions on the shank at all.
In a further embodiment that may be understood as being the inverse
of the embodiment described above, the shank may include a bore, or
cavity that is open at one end and the holder may include a
protruding member, the shank bore being adapted to receive the
protruding member of the holder.
[0039] In general, the greater the number of different orientations
in which it is possible for the tool to be held by the holder, the
more evenly it may be possible for wear to be distributed on the
body of the tool, but the more difficult it may be for the tool to
be held without rotation in use. The optimum balance between these
factors may depend on the operating conditions, the wear resistance
of the tool components and the base in particular, and the type of
rock or stone formation being worked, since these may affect the
nature, rate and degree of tool wear. The optimum may be determined
by straightforward trial and error.
[0040] In use, the working tip may engage a rock (e.g. coal, potash
or other rock), stone, or asphalt material for example by
repeatedly impacting that material with force in order to degrade
it. It may be desirable that the working tip should retain its
structural integrity as much as possible and for as long as
possible, and that it wears away or fractures as little as possible
in order to prolong the working life of the tool.
[0041] With reference to FIG. 7(a), FIG. 7(b) and FIG. 7(c), an
embodiment of a pick tool 100 comprises an attack tool 110 and a
steel holder 120, in which the attack tool 110 may be infinitely
indexable, the configuration not being limited to a predetermined
number of orientations.
[0042] With reference to FIG. 7(b), an embodiment of an attack tool
110 comprises a superhard tip 112 joined to a cemented carbide
support body 114 at an end 119 of the support body 114, the support
body 114 comprising a shank 116. The superhard tip 112 comprises a
superhard structure 112a bonded to a cemented carbide substrate
112b. The shank 116 has a substantially cylindrical form and a
diameter d that is substantially invariant along its entire length.
The support body 114 includes a tapering portion 115 having a
substantially frustoconical form and an end 119 to which the
superhard tip 112 is brazed. In one embodiment, the superhard
structure 112a comprises PCD and may have a rounded or spherically
blunted conical form having an apex, the longitudinal thickness of
the PCD structure 112a at the apex being in the range from about
5.5 mm to 6 mm.
[0043] With reference to FIG. 7(c), an embodiment of a steel holder
120 has a bore 126 configured to accommodate the shank of a support
body of a superhard attack tool, such as that described above with
reference to FIG. 7(b), and a shaft 124 for mounting the holder
onto a tool carrier (not shown). The shank of the superhard attack
tool or pick insert is secured within the bore 126 of the steel
holder 120 in a manner in which the bore abuts and engages at least
part of the shank when the attack tool assembly is in an engaged
condition. The bore 126 extends through the holder 120, providing a
through-hole having a pair of open ends 128a and 128b. A disengaged
condition may then be achieved by heating the holder, thus allowing
the bore to expand and the shank to be released. The shank can then
be re-orientated inside the holder.
[0044] Embodiments of the invention, particularly embodiments in
which the working tip comprises a superhard material such as PCD,
may have the advantage of having extended working life. Embodiments
may have the advantage that the volume of superhard material is
reduced or even minimised, thereby reducing or minimising the cost
of the attack tool.
* * * * *