Note: Descriptions are shown in the official language in which they were submitted.
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NON-ROTATING WASHER FOR TOOL PICK, TOOL AND BLOCK ASSEMBLY,
METHOD TO REDUCE
EROSIVE WEAR AND MATERIAL REMOVAL MACHINE
FIELD
[0001] The present disclosure relates to a rotatable tool pick, particularly
for the
mining, excavating, tunnelling, road planing and/or construction industries.
More
particularly, the present disclosure relates to a rotatable tool pick
incorporating a non-
rotating washer at the interface of a pick shoulder and a corresponding
contact face of
the block or sleeve. A friction fit between a washer bore and a retaining
element on the
pick shank impedes or prevents rotation and the non-rotating washer reduces
the wear
on the contact face of the block or sleeve, which extends the life of the
system. The
disclosure relates to the tool pick with non-rotating washer per se and also
relates to a
block and sleeve assembly incorporating the rotatable tool pick with non-
rotating
washer, a machine incorporating such a block and sleeve assembly, particularly
machines for mining, excavating, tunnelling, road planing and/or construction,
and a
method of mining, excavating, tunnelling, road planing and/or construction
using the
rotatable tool pick with non-rotating washer.
BACKGROUND
[0002] In the discussion of the background that follows, reference is made to
certain
structures and/or methods. However, the following references should not be
construed
as an admission that these structures and/or methods constitute prior art.
Applicant
expressly reserves the right to demonstrate that such structures and/or
methods do not
qualify as prior art.
[0003] All tool picks with washers incorporate some form of a steel shank with
a
ledge to accommodate the washer at installation. As seen in FIG. 1, a
conventional tool
body 10 of a tool pick includes a head end 12 and a shank end 14. The head end
12
includes the seat 16 for receiving a cutting tip 18 therein (a tool pick 20
including the
tool body 10 and a cutting tip 18 is shown in FIGS. 2A and 2B) and a cutting
portion 22
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(here shown with a tapered forward section 22a and a non-tapered section 22b).
After
a puller groove 24, there is a shoulder 26 with a rearward facing surface 28.
Between
the rearward facing surface 28 of the shoulder 26 and an area 30 of the shank
end 14 to
receive a retaining element, there is a ledge 32 defined by a diameter (D)
that is greater
than the diameter of the area 30 that receives the retaining element but is
less than a
diameter of the shoulder 26.
[0004] To protect the contacting surfaces of the tool pick and the body in
which the
tool pick is mounted for rotational motion during operation, for example, a
block and/or a
sleeve, a washer can be included. Conventionally and for shipping and storage
prior to
use, the washer 34 comes assembled onto the shank end 14 of the tool pick 20,
as
shown in FIG. 2A. The washer 34 is placed over the shank end 14 with the
retaining
element 36 in a compressed condition, i.e., with a reduced diameter from the
free state,
which is accommodated by the reduced diameter of the area 30. In the position
in FIG.
2A, the washer 34 is in friction fit contact with the outer surface of the
retaining element
36. FIG. 2B shows the conventional arrangement for the washer 34 on the tool
pick 10
when the tool pick 10 has been installed for use or the washer 34 has
otherwise been
moved axially forward. In FIG. 2B, the washer 34 has been forced axially
forward on
the shank end 14 and contacts the rearward facing surface 28 of the shoulder
26. The
washer 34 is positioned such that the surface of the retaining element 36 is
no longer in
contact with surfaces of the opening in the washer 34 and the washer 34 can
rotate
relative to both the retaining element 36 and the tool pick 10. In practice,
conventional
washers 34 can have some axial movement while positioned on the ledge 32, and
some
portion 38 of the shank, whether the ledge 32 or some other portion, axially
above the
area 30 with the reduced diameter may protrude rearwardly below the washer 34.
[0005] Existing block and sleeve holder systems are prone to failure due to
the
excessive frictional wear between the washer and the contacting surface of the
block or
sleeve. As a tool pick cuts, abrasive fines become trapped between the washer
and the
contacting surface of the block or sleeve. These abrasive fines contribute to
wear and
erosion of the contacting face of the block or sleeve. Such wear can, among
other
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things, shorten the life of the block and sleeve holder system. Furthermore,
such wear
can require premature replacement of the block of the holder system at expense
in
efficiency, time and money.
[0006] Two existing designs of non-rotating washers, U.S. Patent No. 7,195,321
and
U.S. Patent No. 6,692,083, both use a tab, or other mechanical device, to
prevent the
washer from rotating relative to the contact surface of the block or sleeve.
Furthermore,
neither of these designs completely prevents movement of the washer relative
to the
contact surface as there is always "slack" between the mechanical device and
its
corresponding mating surface. This slack allows some rotational movement of
the
washer relative to the contact surface and even small rotational movement can
erode
the contact surface of the block or sleeve over time to deleterious effect.
SUMMARY
[0007] To reduce erosive wear of a contact face of a block or a contact face
of a
sleeve, a washer is positioned between a shoulder of a tool pick and the
contact face
such that the washer is non-rotatable relative to a retaining element.
Reducing rotation
of the washer reduces the wear on the tool pick and associated parts of the
block (or
block and sleeve) holder system.
[0008] An exemplary embodiment of a rotatable tool pick comprises a head
including
a seat for receiving a cutting tip therein at an axially forward end and a
shoulder section
at an axially rearward end, a shank projecting rearwardly from the shoulder
section of
the head, the shank including a reduced diameter portion having an axial
length, a
retaining element positioned about at least a portion of the reduced diameter
portion of
the shank, and a washer with an inner peripheral surface defining a central
opening,
wherein the washer is mounted on the shank via the central opening and is non-
rotatable relative to the retaining element through a friction fit.
[0009] An exemplary embodiment of a tool and block assembly comprises a block
including a body having a bore extending axially from a first side to a second
side, and a
tool pick rotatably mounted in the bore of the block, the tool pick including
a head
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including a cutting tip mounted therein at an axially forward end and a
shoulder section
at an axially rearward end, a shank projecting rearwardly from the shoulder
section of
the head, the shank including a reduced diameter portion having an axial
length, a
retaining element positioned about at least a portion of the reduced diameter
portion of
the shank, and a washer with an inner peripheral surface defining a central
opening,
wherein the washer is mounted on the shank via the central opening and is non-
rotatable relative to the retaining element through a friction fit.
[0010] Another exemplary embodiment of a tool and block assembly comprises a
block including a body having a bore extending axially from a first side to a
second side,
a sleeve mounted in the bore of the block, the sleeve having a bore extending
axially
from a first end to a second end, and a tool pick rotatably mounted in the
bore of the
sleeve, the tool pick including a head including a cutting tip mounted therein
at an axially
forward end and a shoulder section at an axially rearward end, a shank
projecting
rearwardly from the shoulder section of the head, the shank including a
reduced
diameter portion having an axial length, a retaining element positioned about
at least a
portion of the reduced diameter portion of the shank, and a washer with an
inner
peripheral surface defining a central opening, wherein the washer is mounted
on the
shank via the central opening and is non-rotatable relative to the retaining
element
through a friction fit.
[0011] An exemplary material removal machine comprises a rotatable member, and
one or more rotatable tool picks mounted on the rotatable member, wherein the
rotatable tool pick includes a head including a cutting tip mounted therein at
an axially
forward end and a shoulder section at an axially rearward end, a shank
projecting
rearwardly from the shoulder section of the head, the shank including a
reduced
diameter portion having an axial length, a retaining element positioned about
at least a
portion of the reduced diameter portion of the shank; and a washer with an
inner
peripheral surface defining a central opening, and wherein the washer is
mounted on
the shank via the central opening and is non-rotatable relative to the
retaining element
through a friction fit.
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[0012] An exemplary method to reduce erosive wear of a contact face of a block
or a
contact face of a sleeve comprises placing a washer between a shoulder of a
tool pick
and the contact face, wherein the washer is mounted on a shank of the tool
pick via a
central opening defined by an inner peripheral surface and is non-rotatable
relative to a
retaining element positioned about at least a portion of a reduced diameter
portion of
the shank through a friction fit.
[0013] It is to be understood that both the foregoing general description and
the
following detailed description are exemplary and explanatory and are intended
to
provide further explanation of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The following detailed description can be read in connection with the
accompanying drawings in which like numerals designate like elements and in
which:
[0015] FIG. 1 shows a body of a conventional tool pick.
[0016] FIGS. 2A and 2B show a conventional tool pick with two different
positions of
a washer.
[0017] FIG. 3 shows an exemplary tool body for a rotatable tool pick.
[0018] FIGS. 4A and 4B show exemplary embodiments of a rotatable tool pick
with a
washer in different positions.
[0019] FIGS. 5A and 5B show a cross-sectional view (FIG. 5A) and a plan view
(FIG.
5B) of an exemplary embodiment of a washer.
[0020] FIG. 6 is a magnified, partial view of the area of the washer at the
shank-head
interface.
[0021] FIGS. 7A and 7B show, in cross-section, additional exemplary
embodiments
of a retaining element with different sections having different gauges.
[0022] FIG. 8 shows an exemplary embodiment of a tool and block assembly
incorporating an exemplary embodiment of a rotatable tool pick.
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DETAILED DESCRIPTION
[0023] An exemplary tool body for a rotatable tool pick is shown in FIG. 3.
The
exemplary tool body 100 comprises a head 102 and a shank 104. Axis 106 is
shown
about which the tool body 100 and any tool pick 110 formed with the tool body
100 are
rotatable.
[0024] The head 102 includes a seat 108 for receiving a cutting tip therein at
an
axially forward end. The head 102 has a shoulder section 112 at an axially
rearward
end with a rearward facing surface 114. Between the front surface 116 and the
shoulder section 112, the head 102 includes a side surface 118, extending
axially
rearward from the front surface 116 toward the shoulder section 112. The side
surface
118 can be of various forms from being oriented substantially perpendicular to
a central
axis 106 of the tool body 100 to being oriented at an angle a to the central
axis 106 (the
angle a opening rearward), and combinations thereof and the form of the side
surface
118 can be planar, concave, convex or combinations thereof and can optionally
include
other features, such as a puller groove 120.
[0025] The shank 104 projects rearwardly from the shoulder section 112 of the
head
102. The shank 104 includes a reduced diameter portion 122 having an axial
length
(L,) and a retaining element 124 positioned about at least a portion of the
reduced
diameter portion 122 of the shank 104. The reduced diameter portion 122
accommodates a reduced diameter state of the retaining element 124 (shown in
FIGS.
4A and 4B), for example, while inserting the shank 104 into a bore of a holder
or when a
washer is placed over the retaining element. The shank 104 can include
additional
features, such as an annular recess 126.
[0026] The reduced diameter portion 122 is separated axially from the shoulder
section 112 by a first axial distance (di). This first axial distance is
associated with a
portion 128 of the shank 104 between the rearward facing surface 114 of the
shoulder
section 112 and the reduced diameter portion 122 of the shank 104. This
portion 128,
also called herein a ledge section, has a diameter (DL) that is greater than
the diameter
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(Dr) of the reduced diameter portion 122 but is less than a diameter (Ds) of
the shoulder
section 112.
[0027] Exemplary embodiments of rotatable tool picks include a washer 130.
Although described and shown herein with a washer that is tapered, the
disclosed
arrangement and non-rotating principles can work equally as well with a flat
washer and
washers of any suitable form and shape can be used, including those disclosed
and
described in U.S. Patent Nos. 6,113,195 and 6,702,393; and U.S. Patent
Application
Publication No. 2007/0257545, the entire contents of each of these disclosures
are
incorporated herein by reference.
[0028] FIGS. 5A and 5B show a cross-sectional view (FIG. 5A) and a plan view
(FIG.
513) of an exemplary embodiment of a washer 130. The washer has a front main
surface 132 and a rear main surface 134 that each extend from an outer
peripheral
surface 136 to an inner peripheral surface 138, which defines the central
opening 140 of
the washer 130. The front main surface 132 faces in a first axial direction
consistent,
which, when the washer 130 is mounted on the shank 104, is consistent with an
axially
forward direction, and the rear main surface 134 faces in a second, opposite
axial
direction, which, when the washer 130 is mounted on the shank 104, is
consistent with
an axially rearward direction. In the exemplary embodiment shown, the front
main
surface 132 is at a taper angle, (3, to the plane 142 containing the
intersection of the
outer peripheral surface 138 and the front main surface 132, for example at a
taper
angle of from greater than zero to about S. The washer 130 has an overall
thickness
(T) in the axial direction and a thickness (t) at the inner peripheral
surface. Where one
or more of the ends of the inner peripheral surface 138 are radiused or
chamfered, the
thickness (t) is measured from where the radius or chamfer begins on the front
main
surface 132 and/or the rear main surface 134.
[0029] As seen, for example, in FIGS. 4A and 4B, the washer 130 is mounted on
the
shank 104 via the central opening 140 and is positioned over the retaining
element 124.
In FIG.4A, the washer 130 is located axially set-back from both of the axial
ends of the
retaining element 124. Here, the retaining element 124 is in a reduced
diameter
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condition limited outwardly by the diameter of the opening 140 in the washer.
The force
of the compressed retaining element 124 produces an outward force that
establishes a
friction fit with the washer 130, which is non-rotatable relative to the
retaining element
124. As previously stated, this is typically the condition of the tool pick
110 when it is
stored or transported. In FIG. 4B, the washer 130 is shown in the position it
will be in
when installed in a block or sleeve. Here, the washer 130 has been pushed
axially
forward into contact with the shoulder section 112, preferably with the
rearward facing
surface 114 of the shoulder section 112. Because the first axial distance
(di), which is
associated with a reduced size or even absence of a ledge section 128 to
accept the
washer 130, is less than an axial thickness (t) of the washer 130 at the inner
peripheral
surface 138, the washer 130 remains in contact with the retaining element 124.
However, the compressed retaining element 124, i.e., compressed radially
relative to its
free state, acts with a radially outward force on the washer 130, establishing
a friction fit
and preventing the washer 130 from rotating relative to the retaining element
124.
However, the washer 130 is free to rotate relative to the shank 104. This
feature
reduces, if not eliminates, frictional wear on contact faces of the block or
sleeve and
thus extends the life of the block or sleeve.
[0030] In exemplary embodiments, with the washer 130 in the installed
position, for
example, as shown in FIG. 4B, the friction fit can be sufficient, by itself,
to prevent the
washer 130 from rotating relative to the retaining element 124. In alternative
exemplary
embodiments, additional rotation preventing features may be used in
combination with
the friction fit to prevent the washer 130 from rotating relative to the
retaining element
124.
[0031] FIG. 6 is a magnified, partial view of the area of the washer 130 at
the shank-
head interface. FIG. 6 helps to illustrate the arrangement of the washer 130,
the
retaining element 124, the rearward facing surface 114 of the shoulder section
112 and
the ledge section 128, if any. As seen in FIG. 6, when a front main surface
132 of the
washer 130 contacts the shoulder section 112, the inner peripheral surface 138
of the
washer 130 is in contact with a surface of the retaining element 124. As seen
in FIG. 6,
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the reduced diameter portion 122 is axially separated from the shoulder
section 114 by
a first axial distance (di). The first axial distance (di) is less than an
axial thickness (t)
of the washer 130 at the inner peripheral surface 138. The difference in
thicknesses is
illustrated in FIG 6 as distance A, where (t - di) = A. The distance A is
occupied by the
retaining element 124, which extends axially forward between the inner
peripheral
surface 138 of the washer 130 and the surface of the reduced diameter portion
122.
The retaining element 124 can extend axially forward completely to the ledge
section
126, or extend axially forward some portion of the distance A, as long as the
inner
peripheral surface 138 of the washer 130 is in contact with some portion of
the radially
outer surface of the retaining element 124. Accordingly, the washer 130 is non-
rotatable relative to the retaining element 124.
[0032] The non-rotation of the washer 130 relative to the retaining element
140 is in
contrast to the conventional tool pick. Referring again to FIG. 2B, the ledge
32 or some
other portion 38 of the shank axially above the area 30 with the reduced
diameter
protrudes rearwardly below the washer 34. Thus, there is no rotation-
inhibiting contact
between the washer 34 and the retaining element 36 and the washer 34 freely
rotates
relative to the retaining element 36.
[0033] To maximize the forces between the washer 130 and the retaining element
124 contributing to non-rotation, the engagement between the washer 130 and
the
retaining element 124 can be maximized. For example, the distance A can be
maximized and the retaining element 124 can occupy the reduced diameter
section 122
all the way forward to the ledge section 128, thus maximizing the axial length
of
retaining element 124 in contact with the inner peripheral surface 138 of the
washer
130. However, too much engagement can detract from the retention force exerted
by
the retaining element on the surface of the bore when mounted in the block or
sleeve.
Further, too little retention force and the tool pick will be thrown from the
holder. It has
been found that a holding force in the range of about 0.7 kNewtons to about
1.0
kNewtons is suitable. One can adjust the holding force by any suitable means.
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[0034] For example, one can increase the free state of the retaining element
124.
Increasing the free state of the retaining element 124 will not only increase
the radially
outward force applied by the retaining element 124 to the inner peripheral
surface 138
of the washer 130 (and thus contribute to relative non-rotation between the
washer 130
and the retaining element 124), but also will increase the radially outward
force applied
by the retaining element 124 to the bore when mounted in the block or sleeve
(and thus
contribute to increased retention forces for the tool pick within the block or
sleeve).
[0035] In another example, when the retaining element 124 is formed from
metal, a
first section 150 of the retaining element 124 contacting the inner peripheral
surface 138
of the washer 130 has a first gauge and a second section 152 of the retaining
element
124 not in contact with the inner peripheral surface 138 of the washer 130 has
a second
gauge. The first gauge is less than the second gauge so that the first gauge
can
establish sufficient outward force to the inner peripheral surface 138 of the
washer 130
to make the washer 130 non-rotatable relative to the retaining element 124 and
the
second gauge can establish sufficient outward force to the surface of the bore
when
mounted in the block or sleeve to make the retaining element 124 non-rotatable
relative
to the bore.
[0036] In one exemplary embodiment and as shown in FIG. 7A, the retaining
element can have two sections of different gauge with a distinct area of the
change in
gauge. An axial length (L2) of the first section 150 can vary depending on how
much of
the length (L2) will be in contact with the inner peripheral surface 138 of
the washer 130
and can vary to balance the outward forces of the two sections. For example,
since the
amount of holding power is a function of both radial outward force and the
length of
contact between surfaces, varying the length of the sections can be used to
achieve
desired holding power between the washer 130 and retaining element 124 on the
one
hand and between the bore and the retaining element on the other hand. An
example
of a suitable length (L2) is at least as long as the distance A.
[0037] In another exemplary embodiment and as shown in FIG. 7B, the retaining
element 124 can have a continuous or near continuous gauge change from a first
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section 170 at a first end 172 to a second section 174 at a second end 176.
The axial
length (L3) of the continuous or near continuous gauge change can be
coterminous with
the first end 172 and/or second end 176, or the location on the retaining
element 124
where the continuous or near continuous gauge change begins or ends can be at
a
distance separated from the first end 172 and/or second end 176, with the
remaining
axial length (LR) of the retaining element 124 having a near constant gauge.
As an
example and for illustrative purposes, FIG. 7B shows a continuous or near
continuous
gauge change coterminous with the first end 172, while the second end 176
includes a
remaining length having a near constant gauge. The relative lengths of L3 and
LR can
vary, as similarly described herein for axial length L2.
[0038] When a cutting tip 150 is mounted in the seat 106 of the tool body 100,
a tool
pick 110 is formed, as shown in exemplary form in FIGS. 3A and 3B. An
exemplary
cutting tip 160 is made from a hard material. A suitable hard material for the
cutting tip
112 is cemented carbide. An exemplary composition of the cemented carbide
includes
6-12 wt. % Co with balance WC. The tool body 100 can be formed, for example,
of
hardened steel.
[0039] The retaining element 124 can be made of, for example, hardened steel.
Other features that may be included on the retaining element 124 include, for
example,
one or more annular projections 162 that fit into the annular recess 124 to
secure the
retaining element 124 onto the shank 104.
[0040] FIG. 8 shows an exemplary embodiment of a tool and block assembly
incorporating an exemplary embodiment of a rotatable tool pick. An exemplary
embodiment of a tool and block assembly 200 comprises a block 202 including a
body
204 having a bore 206 extending axially from a first side 208 to a second side
210. An
exemplary embodiment of a tool pick 110 as disclosed and described herein, for
example in connection with FIGS. 3 to 7B, is rotatably mounted in the bore 206
of the
block 202.
[0041] The washer 130 is non-rotatable relative to the retaining element 124
and the
retaining element 124 is rotatable relative to the shank 104. In addition, in
one
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embodiment, when the tool pick 110 is mounted in the bore 206 of the tool and
block
assembly 200, the washer 130 is non-rotatable relative to the contact face,
which is the
first side 208 of the body 204 of the holder 202. During use, the tool pick
110 rotates.
However, the washer 130 may rotate relative to the contact face at a first
rate and the
head 102 of the tool pick 110 may rotate relative to the contact face at a
second rate,
where the first rate is lower than the second rate.
[0042] In another exemplary embodiment, a sleeve is first positioned in the
bore 206
of a tool and block assembly 200 and the tool pick 110 is mounted in the bore
of the
sleeve, as is known in the art. In this instance, the contact face is the
axially forward
surface of the sleeve and the washer 130 is non-rotatable relative to this
contact face.
Here again, during use the tool pick 110 rotates. However, the washer 130 may
rotate
relative to this contact face at a first rate and the head 102 of the tool
pick 110 may
rotate relative to this contact face at a second rate, where the first rate is
lower than the
second rate.
[0043] Note that when mounted in the block or sleeve, the retaining element
may
flair radially outward in an area of the washer 130, as compared to the in the
area of the
bore, as the retaining element 124 expands to the limits of the central
opening 140 in
the washer 130.
[0044] The tool and block assembly can subsequently be mounted on a machine
for
use. A base portion 212 of the block 202 is adapted for mounting to a rotating
element
of a mining machine, construction machine, tunneling machining or trenching
machine,
such as Sandvik model MT720 tunneling machine or Voest-Alpine's Alpine Bolter
Miner
ABM 25. An exemplary mining machine comprises a rotating element in the form
of a
rotatable drum, and one or more blocks mounted on the rotatable drum, for
example, by
bolts and or welds. Exemplary embodiments of the tool pick 110 can be mounted
in the
bore of the blocks, with our without the use of a sleeve.
[0045] EXAMPLE: The distance from the shoulder of the tool pick to the area of
the
tool pick that accepts the retaining element is less than the thickness of the
washer. In
this example, the washer thickness is 0.198 to 0.190 inches, and the
corresponding
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area on the shank, i.e., d1, is 0.090 to 0.075 inches. This allows for an
engagement of
0.123 inches maximum and 0.100 inches minimum. The distance, i.e., d1, is
preferably
about 0.083 inches, but it can be as much as 0.189, e.g., minimal engagement,
and as
little 0.000, e.g., maximal engagement. That is, the ledge section 128 can be
omitted
for maximum engagement of the washer 130 on the retaining element 124.
However,
too much engagement can detract from the retention force exerted by the
retaining
element 124 on the surface of the bore 206 of the block or sleeve; too little
retention
force and the tool pick 110 risks being thrown from the holder.
[0046] The disclosed design utilizes a standard washer with a diameter of the
central
opening 140 in the washer 130 about equal to or as much as, for example, about
0.012
inches larger than the bore diameter of the block or sleeve into which the
tool pick will
be inserted. When the central opening is about equal to the bore diameter,
there should
be sufficient retaining force between the retaining element 124 and the bore
of the block
or sleeve to hold the tool pick during installation. When the central opening
140 in the
washer 130 is as much as, for example, about 0.012 inches larger than the bore
diameter, the retaining element 124 is not overly limited in its radial
expansion by the
bore diameter so that a minimal friction force exists between the washer 130
and the
retaining element 140 to have the washer 130 be non-rotating relative to each
other.
[0047] Although described in connection with preferred embodiments thereof, it
will
be appreciated by those skilled in the art that additions, deletions,
modifications, and
substitutions not specifically described may be made without department from
the spirit
and scope of the invention as defined in the appended claims.
[0048] The disclosures in U.S. provisional patent application No. 61/231,095,
from
which this application claims priority, are incorporated herein by reference.
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