U.S. patent application number 13/721576 was filed with the patent office on 2014-06-26 for pick for earthworking machine.
This patent application is currently assigned to ESCO Hydra (UK) Limited. The applicant listed for this patent is ESCO HYDRA (UK) LIMITED. Invention is credited to John Joseph Warren.
Application Number | 20140175853 13/721576 |
Document ID | / |
Family ID | 50973799 |
Filed Date | 2014-06-26 |
United States Patent
Application |
20140175853 |
Kind Code |
A1 |
Warren; John Joseph |
June 26, 2014 |
Pick For Earthworking Machine
Abstract
A pick to be used on an earth working roll for mining,
construction and public works machines such as crushers, surface
miners, milling machines and the like. The pick includes a working
end with holes that extend into the pick and inserts are received
into the holes. The inserts during operation impact and fracture a
consolidated material to separate the material. Impacting the
material generates heat in the pick at the working end of the pick
which must be dissipated and attenuated to limit thermal fatigue in
the inserts that occurs at high temperatures. The inserts in the
working end are configured to dissipate the generated thermal
energy from the inserts to the body of the pick.
Inventors: |
Warren; John Joseph;
(Doncaster, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ESCO HYDRA (UK) LIMITED |
Rotherham |
|
GB |
|
|
Assignee: |
ESCO Hydra (UK) Limited
Rotherham
GB
|
Family ID: |
50973799 |
Appl. No.: |
13/721576 |
Filed: |
December 20, 2012 |
Current U.S.
Class: |
299/101 |
Current CPC
Class: |
E21C 35/183
20130101 |
Class at
Publication: |
299/101 |
International
Class: |
E21C 35/183 20060101
E21C035/183 |
Claims
1. A pick for attachment to a driven roll for working a
consolidated material comprising: a head configured to separate the
consolidated material including: a strike face; holes that open at
the strike face; and inserts received in the holes that extend
beyond the strike face to impact the consolidated material; and a
body that contacts the driven roll.
2. The pick of claim 1 where the inserts are equidistant about a
center point of the strike face.
3. The pick of claim 1 where the holes are parallel to each
other.
4. The pick of claim 1 where the angle between any two holes is
between 5 and 40 degrees.
5. The pick of claim 1 where the inserts are made of one or more
material selected from the material group comprising carbide,
steel, diamond and ceramic.
6. The pick of claim 1 where the hardness of at least one of the
inserts is different than the hardness of the other inserts.
7. The pick of claim 1 where the head receives three inserts.
8. The pick of claim 1 where the head receives four inserts.
9. The pick assembly of claim 1 where the holes are all parallel
viewed from a first perspective and the angle between two of the
holes is between 5 and 40 degrees viewed from a perspective
orthogonal to the first perspective.
10. The pick of claim 1 where the pick includes a shank to be
received in an opening of a tool holder secured to the roll.
11. The pick of claim 10 where the pick includes a shoulder
proximate to the shank that abuts the tool holder on fully
receiving the shank in the opening.
12. The pick of claim 10 where the holes extend 30-50
millimeters.
13. A pick assembly to be used on a rotating drum to separate a
consolidated material comprising: a pick including a head with a
strike face; holes that open at the strike face; a holder mounted
on the drum to receive the pick; and a plurality of inserts
received in the holes.
14. The pick assembly of claim 13 where the head includes a
longitudinal axis inclined at an angle between the direction of
rotation of the drum and a radial of the drum and the inserts at
the face are equidistant from the longitudinal axis
15. The pick assembly of claim 13 where the inserts comprise one
material selected from the group of cemented carbide, steel,
diamond and ceramic.
16. The pick assembly of claim 13 where the holes are parallel to
each other.
17. The pick assembly of claim 13 where the holes converge toward
the strike face.
18. The pick assembly of claim 13 where at least one of the holes
is inclined from at least one other hole at an angle between 5 and
40 degrees.
19. The pick assembly of claim 13 where the inserts are parallel to
each other when viewed from a first perspective and the angle
between a first hole and a second hole is between 5 and 40 degrees
viewed from a perspective orthogonal to the first perspective.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a cutter tool, primarily for use
in mineral winning, such as coal mining, but also usable for other
underground purposes such as tunnel or roadway driving, or above
ground for civil engineering works such as road planing and trench
cutting, whether with drums or endless chains, both on land and
underwater.
BACKGROUND OF THE INVENTION
[0002] A number of machines involved in mining, construction and
public works use rolls or drums that are driven for the crushing,
mining, milling and the like of earthen materials. These earth
working rolls or drums include an array of pick assemblies to
engage and separate a consolidated material into smaller portions
that can be further separated in subsequent operations. A pick
assembly may include a pick releasably attached to a holder secured
to the drum or roll. The pick includes a head configured to contact
the material and separate it. The picks are wear parts that are
replaced after a certain length of use.
[0003] Conventional mineral cutter picks of the shearer type are
produced as steel forgings and may include a rectangular section
shank whereby the pick is releasably latched in a rectangular
receiving aperture of the tool holder or block secured to the roll.
The head of the pick projects from the tool holder and above the
roll surface.
[0004] The head of the pick is typically notched at its forward end
to provide a seat into which is brazed a hard material (usually
tungsten carbide) as a tip. The tip may be approximate in width to
the head of the pick so as to be capable of cutting clearance for
the head. 50 to 100 picks may be attached to a shearer drum of a
longwall coal, potash etc. cutting machine. This type of machine
has been in use for decades.
[0005] In operation, the impact of the tips can generate
significant heat. Dissipation of this heat is critical as the
carbide tips are subject to thermal fatigue when they consistently
reach or operate at high temperatures. Inefficient operation of the
picks due to damage or wear can also generate excessive heat,
raising the temperature of proximate parts of the drum and
significantly degrading structural properties of components.
[0006] The head of a pick may be damaged by inadvertent collision
with a roof support or by hitting hard inclusions in the ore seam
such as rocks. When this occurs, a portion of the head of the pick
may break away taking the tip with it. The remaining portion of the
pick head, without the hardened tip, continues to impact ore
material as the machine operates and the drum rotates. The damaged
pick then sustains more damage which results in a shortened useful
life and lower machine efficiency.
SUMMARY OF THE INVENTION
[0007] The present invention pertains to an improved pick for use
on an earth working roll for mining, construction and public works
machines such as crushers, surface miners, underground mining
machines, milling machines and the like. The pick includes a head
with multiple tips or inserts in a strike face of the pick that
impact the worked surface. The inserts are positioned in holes of
the pick head that open at a face of the head and the inserts
extend beyond the face. The inserts are configured to impact the
surface of the consolidated material more efficiently and dissipate
generated heat more efficiently to the body of the pick.
[0008] The head of the pick protrudes beyond the tool holder with
the head oriented away from the drum and in the direction of
rotation of the roll. The inserts are a hard material configured in
one construction as elongate rods of any cross-section
approximately the same dimension as the holes in the face. The
inserts may be held frictionally in the hole, brazed in place,
soldered, glued or by any other method that maintains their
position in the hole during operation. Multiple small inserts as
compared to one relatively large carbide tip positioned in the head
presents smaller areas of carbide impacting the target material,
generating less heat.
[0009] The pick is configured so that the inserts initially impact
the earthen material as the drum rotates. Any number of two or more
inserts may be positioned in the head of the pick. Positioning the
inserts in the head of the pick with an appropriate configuration
and separation between the inserts can more efficiently transfer
heat away from the inserts during operation. Where the generated
heat can efficiently flow from the carbide tips to the body of the
pick and the holder, the life of the inserts can be extended and
downtime and expense for replacing the picks can be reduced.
[0010] In a first embodiment, the tips are configured in the head
so that they are spaced apart about a central axis of the strike
face or contact face of the pick and extend beyond the face. The
multiple tips protruding from the face impact the target material
over a smaller contact area and generate less heat than a single
large tip.
[0011] In a second embodiment the elongate inserts are parallel to
each other in the head along their length. Preparing the head of
the pick to accept parallel inserts is a less complex and lower
cost process than other configurations and the closely spaced tips
impacting the material work more efficiently than a single large
tip.
[0012] In a third embodiment the holes with inserts are spaced
apart in the head of the pick and the inserts converge toward the
face to a closely spaced configuration. Heat generated at the tip
of the insert from impacting the target material is more
efficiently transferred to the head and body of the pick in this
embodiment by dissipating the heat over a larger body area than
would occur with the picks in a parallel configuration.
[0013] A pick assembly configured to operate and dissipate heat
more efficiently from the inserts to the head would be advantageous
by reducing insert thermal fatigue, machine downtime and power
consumption.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a depiction of an earth working operation
including a roll drum with picks.
[0015] FIG. 2 is a side cross section view of a pick with inserts
in accordance with the present invention including a tool holder
mounted to a drum.
[0016] FIG. 2A is a side cross section view of an alternative
configuration of a pick with inserts in a carrier received by the
head of the pick.
[0017] FIG. 3A is a perspective view of a pick with three
inserts.
[0018] FIG. 3B is a perspective view of a pick with four
inserts.
[0019] FIG. 4 is a cross- section view of a pick with three inserts
along line 4-4 of FIG. 2.
[0020] FIG. 5 is a side cross section view of a pick with
inserts.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] FIG. 1 depicts an earth working operation including a face
miner with pick assemblies for extracting earthen material such as
coal in a mining operation. The operation is shown as including a
mining machine 4 with a driven drum, roll or cylindrical body 6
mounted with pick assemblies 8 including picks 10 for impacting the
ore seam or consolidated earthen material 12 as drum 6 rotates.
Picks 10 are mechanically attached or secured to rotating drum or
cylindrical body 6. Earthen material 12 to be extracted is
typically in a seam and rotating drum 6 passes across the mine face
so the picks impact the face and dislodge material from the seam in
manageable portions. Picks 10 impinge on the material with adequate
speed and force to fracture the material.
[0022] The spacing of the picks determines the size of the
dislodged material, but also is a factor in stress on individual
picks and heating of components. The mined material is typically
dropped onto a conveyor and transported away to a roll crusher or
other processing. Pick assembly 8 is one of many similar assemblies
attached to drum 6, often in staggered rows.
[0023] In all figures, like components use similar numbering. FIG.
2 is a cross section view of pick assembly 8 mounted to drum 6.
Drum 6 has a direction of rotation R and a radial direction r away
from the axis of drum 6. Pick assembly 8 as shown includes a pick
10 and a tool holder or base 14. Pick 10 has a proximal end 10A and
a distal end 10B. Pick 10 is shown with a shank 18 at proximal end
10A which is the portion of pick 10 received by holder 14. Pick 10
is shown with a head 22 at distal end 10B and a body 16 generally
between shank 18 and head 22.
[0024] Head 22 tapers forward and away from body 16 and is
configured to contact consolidated materials to be separated. In
FIG. 2 head 22, indicated by a dotted line, generally extends away
from the drum and in the direction of rotation R. Head 22 defines a
longitudinal axis 20 and includes a strike face or contact face
22A. The pick body 16 is shown with a pry point 16A at a forward
portion of body 16 configured to receive a pry bar for removing
pick 10 from holder 14. At a rear portion body 16 includes an
opening 16B associated with a water spray system not shown in this
embodiment.
[0025] Head 22 includes face 22A with holes 24 configured to
receive inserts 26. In a preferred embodiment, holes 24 with
inserts 26 are shown inclined to each other and converging toward
face 22A. Each hole 24 and insert 26 may define an axis and the
inclination of the holes may be defined by an angle between the
axis of the hole and the longitudinal axis 20 of head 22,
preferably between 5 and 20 degrees. Alternatively, the inclination
of the holes may be defined by an angle .alpha. between holes in
the head 22. Hole 24 may be inclined an any angle .alpha. that fits
within the envelope of head 22, but preferable is between 5 and 40
degrees.
[0026] In one embodiment, the axes of adjacent holes 24 may be
substantially parallel to the longitudinal axis 20 as shown in FIG.
4. In another embodiment the inserts may be distributed about the
longitudinal axis, each insert 26 with the same inclination to axis
20 as shown in FIG. 2. In another alternative embodiment, inserts
26 may be parallel to each other and axis 20 in one perspective.
Then from an orthogonal perspective one or more inserts 26 are
inclined to axis 20.
[0027] Holes 24 may extend more than a quarter of the distance
between head 22 and the top of shank 18. Preferably, hole 24
extends 30 to 50 millimeters in depth. The length of inserts 26 and
depth of hole 24 affects heat propagation, structural integrity of
the inserts and transfer of impact forces from the inserts to head
22 and body 16 of pick 10. Holes 24 and inserts 26 may be round,
triangular, rectangular or square in cross section or any other
shape and can be manufactured by several processes.
[0028] Holes 24 may not extend substantially into head 22. Holes 24
in an alternative embodiment may be of adequate depth to accept an
insert configured as a tile and to limit transverse movement of the
tile on strike face 22A.
[0029] In a preferred process, holes 24 are drilled into head 22
and inserts 26 inserted into the drilled holes. Round holes are
most easily drilled, but square and other cross-sectioned blind
holes can be produced using more sophisticated machining
processes.
[0030] In another embodiment pick 10 includes a carrier for inserts
26 as shown in FIG. 2A. FIG. 2A includes a pick 10 with a shank 18
and a head 22 similar to the pick of FIG. 2. In this embodiment
pick 10 further includes a carrier 30 and a carrier opening 32.
Holes 24 are machined in carrier 30 and inserts 26 are positioned
into each hole 24. Head 22 then receives carrier 30 with the
inserts in carrier opening 32. As an example, a square hole can be
configured in carrier 30 by square swaging through the carrier to
configure the hole and a square insert 26 positioned in the swaged
square hole 24. Carrier 30 can then be mounted to head 22 by any of
various means including threading the carrier and carrier opening,
brazing or welding. Swaging a hole in carrier 30 is a lower cost
process than other forms of machining for some hole
configurations.
[0031] In still another embodiment, carrier 30 of FIG. 2A could be
formed around inserts 26. Inserts 26 could be held in position in a
carrier mold or in a carrier opening 32 in head 22. A casting
material such as bronze, aluminum, epoxy or other compatible
material is then poured around inserts 26. If a carrier mold is
used, the carrier 30 is separated from the mold and received by
carrier opening 32 of head 22.
[0032] Casting around inserts 26 would provide for any shape of
insert 26 to be used, as well as inserts that vary in cross section
along their length. Heat transfer characteristics, wear and
structural properties in head 22 can be modified by appropriate
selection of casting materials.
[0033] Returning to FIG. 2, tool holder 14 is shown with an
aperture or opening 14A configured to receive shank 18. Shank 18 is
preferably rectangular in cross-section, but may be oval or round
or any other shape which is compatible with the holder. Holder or
base 14 is secured to the surface of drum 6 or in a depression or
indentation for a lower profile by any means that reliably retains
the holder such as welding or bolting. Pick 10 may further include
a shoulder 14B. With shank 18 fully inserted in opening 14A,
shoulder 14B abuts an edge of opening 14A limiting the depth of
insertion.
[0034] Pick assembly 8 is shown with a resilient retention feature
28 in shank 18. Retention feature 28 may be a button inserted into
a hole of shank 18 and configured to work cooperatively with a
feature of holder 14 to retain pick 10 in holder 14. Shank 18 may
be inserted and extracted from tool holder 14 along radial
direction r. Longitudinal axis 20 may be may have an angle of
inclination between the direction of rotation R and the drum radial
direction r so that is it is inclined in the direction of rotation.
Pick 10 may not have a shank. Pick assembly 8 may be secured to
roll 6 by another means such as welding or bolting holder 14 or
pick base 16 to roll 6.
[0035] The portion of head 22 proximate to face 22A may be
configured with a narrower cross section, acutely angled surfaces,
sharper edges and smaller radii of curvature than sections of pick
10 and head 22 farther from face 22A. This forward area is also
more exposed to impact from material separated by inserts 26. This
makes the area around face 22A more prone to fatigue cracking,
chipping and fracture. Having the end of insert 26 abut the body of
pick 10 at the bottom end of hole 24 farther from face 22A, allows
impact forces to be transmitted to an area of pick 10 less prone to
damage. This reduces stress in the area proximate to face 22A and
increases service life of pick 10.
[0036] When pick 10 is damaged, a portion of head 22 may be broken
off from pick 10. With multiple inserts, a remaining portion of
head 22 may retain one or more inserts that continue to efficiently
impact earthen materials 12. In previous configurations with a
single large tip, any damage to head 22 tended to separate the tip
from the head, severely reducing the efficiency of the pick.
[0037] Pick 10 and tool holder 14 may be composed of iron, steel or
any other material that is durable enough to withstand continuous
impacting and abrading of the surface by the fractured materials.
Inserts 26 are selected to be a much harder material than pick 10
and are preferably cemented carbide, diamond or ceramic, but other
materials can be used. The inserts may vary in hardness. One insert
may have a different hardness than the other picks in the same pick
head.
[0038] Carbide may have twice the thermal conductivity of steel.
With the higher thermal conductivity, insert 26 acts as a radiator
and the entire length of the insert will tend to stay at a higher
temperature than the surrounding steel. This temperature
differential in turn drives a higher rate of heat transfer or heat
flux along the entire surface of the insert.
[0039] Three smaller inserts 26 with a larger surface area will
dissipate the heat more readily than the single larger tip. For the
purpose of illustration only and as an example, insert 26 may be
round with a diameter of 1 millimeter (mm) and a length of 10 mm.
The total circumference of 3 tips, each with a diameter of 1 mm is
9.4 mm and a typical single large tip may have a diameter of 1.85
mm inserted in the head for a circumference of 5.8 mm. The inserts
significantly increase surface area for transfer of heat from the
insert to the steel body. Making insert 26 longer than a standard
single tip also significantly increases the surface area for heat
transfer to the steel body. Drilling insert holes 24 so they
diverge from face 22A into the head of pick 10 provides a further
advantage in dissipating the heat over a greater volume of pick
10.
[0040] A pick operates over a wide range of temperatures and
mismatch of thermal expansion between components can cause internal
stresses. The coefficient of expansion of the carbide, 5.times.10-6
m/m-K, is less than that of steel which is 13.times.10-6 m/m-K.
Using three smaller diameter tips results in less tension between
the steel and carbide as the contact area is greater. The brazing
and soldering materials also act as an interface between the
inserts and the head and compensate for mismatch at the
interface.
[0041] The service life of a pick is a function of the volume of
carbide removed during operation (wear rate) as well as the
susceptibility of insert 26 falling out of pick 10. When the
portion of insert 26 remaining in the head is small, it is more
susceptible to leverage from side impacts that can extract the
insert from head 22 and face 22A. The smaller diameter insert is
less likely to be extracted by side forces because of the
mechanical advantage that it has over the larger tip. For example,
when both tips wear down to 5 mm long, there is a higher extracting
force exerted by side or angled impacts on the large tip than the
smaller insert because of its larger diameter.
[0042] A large single tip is usually sized to the same general
width as head 22 to limit wear to the head. The smaller diameter
inserts 26 leave the head 22 of pick 10 more exposed to the
abrasive materials even though inserts 26 make the primary impact
on the consolidated materials to separate it. This results in more
wear of head 22. Insert 26, a much harder material than head 22 and
body 16 of pick 10, has a lower wear rate.
[0043] With an optimal tip length (the portion of insert 26
extending beyond the face 22A), wear and erosion of head 22 and
insert 26 are minimized. If insert 26 extends beyond head 22 too
far, it is susceptible to lateral forces and portions of the insert
tend to break off. Where exposed tip lengths of inserts 26 are
short, head 22 wears at a higher rate, exposing the inserts. Pick
10 can continue in service as long as inserts 26 are retained in
head 22 with an adequate tip length.
[0044] FIG. 3A is a perspective view of an embodiment of pick 10
with three inserts 26 and longitudinal axis 20 passing through the
center of head 22 of pick 10. The three inserts are distributed
about longitudinal axis 20 with 120 degrees between each
insert.
[0045] FIG. 3B is a perspective view of an alternative embodiment
of pick 10 shown with four inserts 26 and longitudinal axis 20.
Inserts 26 are distributed about longitudinal axis 20 with 90
degrees between each insert. There can be any number of two or more
inserts 26 in head 22 and in any configuration. The two
configurations shown are examples for illustration.
[0046] FIG. 4 shows an alternative configuration of pick 10. Pick
10 in FIG. 4 is a section view from FIG. 2 showing a top view of
inserts 26 and longitudinal axis 20. In this embodiment in this
perspective inserts 26 are parallel to longitudinal axis 20 while
from the orthogonal perspective of FIG. 2 each insert is inclined
to longitudinal axis 20 at the same angle.
[0047] FIG. 5 is a side view of an alternative pick 10 in cross
section, again showing three inserts 26. In this view, orthogonal
to a top view such as FIG. 4, and in contrast to FIG. 2, one or
more inserts are inclined to axis 20 with other inserts parallel to
axis 20.
[0048] The present invention pertains to picks for an earth working
roll or roller such as used in roll crushers, surface miners,
milling machines and the like. The use of relative terms such as
forward, front, rear or sides or the use of specific shapes is not
intended to be limiting, but rather to more clearly illustrate the
invention. Also, picks as described here are shown primarily in the
context of mining machines. Nevertheless, the invention is not
limited to this operation. Picks in accordance with the invention
are also suitable for use in conjunction with other earth working
machines involving the use of driven rolls with picks such as
single roll crushers, scroll crushers, surface miners, underground
mining machines, milling machines and the like.
* * * * *