Note: Descriptions are shown in the official language in which they were submitted.
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REPLACE/aBLE UIfEAR LIP FOR ~N E~CCAV~4TOR BUCKET
FIELD OF THE INVENTION
[0001] The invention relates to excavating equipment, and in particular
excavation buckets and replaceable lip protectors for same to permit bucket
renovation after extensive wear.
Ba4CKGROUND OF THE INVENTION
[0002] Excavator buckets such as those used in hard rock mining operations
generally experience a higl-r level of wear on the exposed lower lip,
requiring regular
replacement of the lip protector portion of the bucket. Typically, bucket
renovation is
accomplished by providing a removable lip region which is rigidly fastened to
the
bucket by welding same onto the Power bucket plate. Replacement of the lip
protector component requires cutting of the welded attachment, followed by
welding
a new lip element in place. Optionally other components may be replaced such
as
corner members. In an underground mining environment this requires costly
containment or gas dispersal systems in order to carry out the work safely, or
alternatively that the bucket be carried to the surface in order that the work
may be
carried out in an outside shop located on the surface. The large buckets used
in
modern LHD mining operations may be too large to be carried whole to the
surface,
requiring such buckets to be cut in half before they are brought to the
surface for
maintenance work. The refurbished bucket is then restored after it has been
brought back into the subsurface mine environment. Regardless of how it is
carried
out with conventional equipment, maintenance work of this nature is time
consuming, costly and removes costly mining equipment from operation for a
protracted period.
[0003 Modern underground mining operations often make use of an
excavator bucket system and method referred to as a "Load, Haul, Dump" ("LHD")
machine, in which an excavator machine provided with a relatively large bucket
is
used to haul broken-up ore or rock from a face to a relatively distant chute
or other
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removal location which is within the mine but at some distance from the rock
face.
This system eliminates the use of a temporary subsurface rail line and car
system to
carry the ore over this distance. However, such a method places great reliance
on
large excavator buckets and imposes a heavy wear load on the bucket, in
particular
the bucket lip. This may be addressed by providing replaceable wear protectors
that cover the exposed lip.
[0004] A bucket for L.H.D. use may include a lead, or prow-shaped extension
at the lower bucket lip to protect the bucket shell from wear and enhance its
scooping abilities. Typically, an operator is provided with a choice of
several
different lead configurations for different mining environments. Hence,
multiple lip
wear protectors must be provided in a typical mining operation to accommodate
different lead configurations, including both the front-to-back displacement
of the
lead and the overall side-to-side width of the bucket.
[0005 Conventional bucket lip systems include the "Esco Delta V"TM
prefabricated lip assemblies. These consist of a provr-shaped lead in which
the
exposed leading edge is protected by weld-on replaceable lip wear elements.
Cast
corner pieces are also provided, comprising vertical plates for welding onto
opposed
sides of the assembly. The assembly is intended to be welded onto the lower
plate
of an excavator bucket, with the lip wear elements being periodically replaced
by a
cutting and welding operation as described above. A similar system is sold by
Hensley, which includes forwardly-protruding teeth. f~eplaceable lip
protectors are
also disclosed in U.S. Patent 3,995,384 to Wood, which describes replaceable
bucket lip protectors or teeth. The lip protectors and 'the lower bucket lip
are
provided with mating or interlocking components for r~eleasably fastening the
lip
protectors to the bucket and retaining same in position by means of a
removable
pin.
[0006, In order to avoid the considerable time and expense involved in
replacing conventional welded-on lip wear protectors, it is desirable to
provide lip
protectors which mechanically fasten to the excavator bucket, for example with
bolts
or pins, in order to permit easy and simple replacement of these elements in
the
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subsurface environment. Further, it is desirable to provide a system and
method to
permit the operator to readily assess the wear status of the replaceable
elements in
order to inform him when these elements require replacement.
SUMMARY OF THE INidE~ITIO~I
[0007] In general terms, the present invention comprises replaceable wear
elements which are mounted to an excavator bucket front shell, consisting of a
prow-shaped base plate and an array of mechanically attached lip wear
protectors
for protecting the exposed front lip of the base plate. The base plate has a
forwardly
extending lead terminating in a central tip, thus giving its leading edge a
chevron
shape. The rear edge of the base plate includes a suitable welding surface
such as
a weld preparation ledge for welding the plate onto the lip of the bucket
shell. The
segments each have a parallelogram shape for attaching in side-by-side array,
and
include a horizontal rearward-facing groove (i.e. opening to the rear of the
segment)
to snugly receive the base plate. Mechanical fasteners such as bolts are
provided
to attach the lip wear segments to the base plate. Preferably the lip wear
segments
are generally tapered from front to rear with an arcuate upper surface and a
flat
lower surface which angles downwardiy and rearwardly such that the segment
includes a heel that protrudes below the base plate and the corresponding
bucket
shell for additional wear resistance.
[0008] Preferably, the horizontal groove within the segment tapers inwardly to
snugly receive a base plate having a corresponding bevelled front edge region
for
an improved fit between these elements.
[0009] Corner wing segments are provided on either side of the bucket to
effectively extend the scooping region of the bucket. These segments are L-
shaped
(when seen from a front elevation) with a vertical plate which extends the
side plate
of the bucket and a horizontal plate which merges with the lead. The wing
segments may include replaceable inside wear plates. The horizontal plates of
the
wing segments include a bevelled front edge which is flush with the front edge
of the
base plate and has the same cross-sectional configuration (thereby forming an
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extension of the forward edge) to snugly r eceive a lip wear protector. The
lip wear
protector may overhang the corner segment laterally thus permitting a degree
of
flexibility in selecting the size of the lip wear protectors when assembling
these
elements onto a given bucket which has a base plate and corner members pre-
mounted.
[0010] The invention further includes excavation buckets which include the
components described herein, provided either installed to the bucket or as a
kit.
[0011] Having thus generally described this invention, the invention will now
be described with more particularity by way of a detailed description of an
embodiment and variations thereon.
DETAILED DESCRIPTION OF THE DRAWINGS
[0012] FIGURE 1 is a perspective view of an excavator bucket, lead and lip
wear protector array according to the invention, in an exploded view.
(0013] FIGURE 2 is a side elevational view of the circled portion of the lead
shown in Figure 1.
[0014] FIGURE 3 is a plan view from above of an excavator bucket, lead and
lip protector array.
[0015] FIGURE 4 is a side elevational view from the direction indicated as 4-4
in Figure 3 .
[0016] FIGURE 5 is a sectional view along fine 5-5 of Figure 3.
[0017] Figure 6 is a sectional view along line 6-6 of Figure 3.
[0018] FIGURE 7 is a perspective view of another embodiment of the lip wear
protector according to the present invention.
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DETAILED DESCRIPT10N OF TFiE INVENTION
[0019] Referring to Figure 1, an excavator bucket 10 suitable for use with the
present invention includes a curved back plate 12 joining with generally fiat
upper
and base portions 14 and 16, and sidewalls 18. Typically the bucket 10 is made
of
heavy gauge mild steel. The base16 includes a forward lip or edge 17, which as
discussed below is capped with protective elements. The sidewalls 18 include
generally central apertures 20 for pivotal attachment to a pair of opposed
lateral
hydraulic rams of the mechanical components of the loader, which are not
shown.
A third, central hydraulic ram 22 is also pivotally mounted to the rear face
of the
bucket. The excavating machine (not shown) typically has sufficient power to
force
the bucket into the rubble pile by utilizing the forward momentum and driving
force
developed by the machine engine. The machine will typically include a
levelling
system to maintain the bucket at dead level.
[0020) A prow-shaped base plate 30 is welded to the front edge 17 of the
bucket 10, the plate 30 being characterized by a lead or forward protrusion of
the
middle region relative to the sides. The base plate 30 may be made of mild
steel or
a high carbon steel for improved wear characteristics. As well, the base plate
30
may have a greater thickness than the bucket plate, for improved wear. The
base
plate 30 has a flat upper surface which when the lead plate is fastened to the
bucket
in the intended fashion, is flush with the adjacent innE;r surface of the
bucket. The
leading edge 32 of the base plate 30 is prow or chevron-shaped in plan, with
opposed sides 34 of the leading edge 32 converging towards a central tip 36.
The
lead is thus characterized by a forward displacement of the tip 36 relative to
the
outermost parts of the leading edge. As seen in Figure 2, a region of the base
plate
30 which is immediately aft of the leading edge 32 tapers towards said leading
edge, with the taper being defined by an upwardly angled portion 38 of the
lower
surface of the plate. The tapered portion 38 has a taper of between 0°
and 30° from
the horizontal, with a preferred taper being about 10°. The tapered
portion
terminates with a squared-off leading edge 32.
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(0021] The rear edge 40 of the base plate 30 is welded to the lower portion
16 of the bucket 10. A flush weld line is formed by ~>roviding the rear edge
40 of the
base plate with an upper tapered region, such when the respective surfaces 32
and
40 abut, an upwardly opening channel opening is formed therebetween to receive
a
weld line.
(0022] The lead, or forward protrusion of the tip 33 relative to the side
edges
of the base plate 30, provides an improved scooping operation of the assembled
excavator bucket when in use. The lead distance is designated in Figure 1 as
a,
which represents the forward displacement of the tip 33 relative to the
fonrvard side
corners of the base plate 30. The amount of lead a will be selected in part by
the
expected conditions to be encountered by the bucket in the particular mining
operation. Hence, the present invention contemplates a range of lead
distances.
Without intending to be restricted to any particular range of lead distances,
a
convenient range for distance a is between 8 and 12 inches. However, it will
be
seen that the actual lead amount will vary depending on the bucket width and
the
expected use of the bucket.
(0023) Opposed wing segments 44 at each lower side corner of the assembly
are provided to provide improved scooping ability. The wing segments 44, seen
in
Figures 1 and 4, each are generally L-shaped in front: elevation, comprising a
triangle-shaped vertical side plate 46 and a horizontal floor plate 48. The
vertical
plate 46 forms a gusset-like extension of the vertical :~idewall18 of the
bucket 10 to
effectively increase the bucket carrying capacity. ThE; floor plate 48 has a
cross
sectional front to rear configuration identical or substantially identical to
the base
plate including a tapered forward edge 45 to snugly receive a lip wear segment
60,
described below. The forward edge 45 protrudes forvvardly of the side plate,
in
order to permit the lip wear segment 60 to protrude or overhang laterally
beyond the
edge of the wing segment 44. This permits use of a variety of sizes of wear
segments 60 without being required to precisely fit between the opposed wing
segments 44. A rearward-facing edge 50 of the wing 44 is bevelled for welding
to
the corresponding lower corner of the bucket 10. The floor plate 48 is
generally
rectangular in plan view, but with its inside rear corner 51 being at an angle
to abut
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with an outwardly flared region 53 of the base plate 30. The inside edge 54 of
the
plate 48 abuts the outer side edge 55 of the base plate 30 and is welded
thereto for
a rigid attachment. When these two plates are joined, they effectively form a
monolithic plate with flush upper and lower surfaces and a continuous bevelled
front
edge. Hence, the bucket 10, base plate 30 and wing segments 44 when welded
together effectively form a rigid monolithic unit. They corners are protected
from
wear by replaceable corner wear shrouds 57 which are bolted over the side
plates
46 of the wing segments 44. The exposed upper edge 54 of the segments 44 may
be bevelled.
[0024] The wing segments 44 include reinforced exterior corners 59 which
protrude downwardly and laterally outwardly from the base plate thereby
providing
further wear protection.
[0025] The base plate 30 includes an array of unthreaded holes 56 for
receiving fastening bolts 58 for the lip wear elements 60, as will be
described below
with reference to Figures 1, 3 and 6.
[0026] The leading edge of the base plate 30 i.s protected against wear by an
array of lip wear segments 60 that are removably fasv~tened 'to the base
plate. The lip
segments 60 have a parallelogram shape {with non-right corner angles) when
seen
in plan. Each segment 60 is generally planar, comprising upper and lower
surfaces
61 (a) and (b), opposed lateral edges 63 and leading and trailing edges f5(a)
and
(b). The parallelogram shape corresponds with the angle of the leading edge 32
of
the corresponding base plate 30 such that when mounted the lateral edges 63
are
aligned with the main axis of the excavator and the leading and trailing edges
65 (a)
and (b) are parallel to the leading edge of the base plate 30. Thus, it is
contemplated that the corner angles of the lip segments 60 will range from
90° (i.e.
for use with a base plate with no lead) to about 20° (i.e. for use with
a base plate
having a width of about 54 inches and a lead of about 10 inches. However, it
will be
readily seen that this range is merely an example and the segments 60 may
exceed
this range.
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(0027) The segments 60 are preferably mounted in a side-by side array such
that neighbouring segments nearly abut each other leaving a narrow gap to
present
a nearly continuous exposed surface with narrow uniform gaps between the
segments. Alternatively, the segments 60 may be rr~ounted in an abutting
gapless
array.
[0028] As seen in Figure 3, the segment array comprises left and right hand
segments 60(a) and 60(b) for mounting on opposed sides of the base plate 30.
The
upper surface 51 (a) of each segment includes a concave arcuate (arc-shaped)
leading portion 64. The Power surface 61 (b) includes a forward region 66
opposed
to the arcuate portion 64, which is substantially flat and upwardly forwardly
sloping,
thereby forming a tapered forward region ~o the segment 60 in which the upper
surface 64 is arcuate and the lower surface 66 is generally flat. The leading
edge
65(a) of the segment 60 is squared off. The rearward portion of the segment 60
is
substantially thicker than the forward portion and includes spaced apart
horizontal
upper and lower flanges 72 and 74, which form the upper and lower walls of a
horizontal channel 76 opening rearwardly. The lower' filange 74 protrudes
further
rearwardly than the upper flange 72 and is substantially thicker in cross
section than
the upper flange to provide a "heel" to the assembly vvhich provides
additional wear
protection at the exposed lower surface of the segments 60 which typically
experience a high degree of wear from bucket contact on rough surfaces. The
bucket itself (which is very costly relative to the replaceable elements
described
above) is thus more protected from wear. The internal horizontal channel 76
has a
tapered innermost region 80 terminating in a squared floor 90, corresponding
with
the tapered leading edge 38 of the base plate 30. The respective male and
female
components are machined for a tight fit to prevent urnvanted movement of the
lip
elements.
[0029] The lip segments 60 are releasable fastened to the lead plate 30 by
mechanical fastening elements, which in the illustrated example comprise bolts
58
extending through aligned apertures 56 within the wear elements 60 and base
plate
30. A recessed region 80 within the lower flange of the lip element permits
the bold
head to be fully recessed. Preferably, the bolts 58 are tightened against a
nut such
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as a StoverTM lockout 88 to resist back-off in adverse conditions which may be
experienced by the device. A reasonably precise fit between the lip wear
elements
60 and the base plate 30, together with a suitable fastener such as a bolt and
nut,
provides for an essentially rigid connection between components which reduces
metal fatigue and reduces bolt shear stresses. The resulting connection is of
similar
strength to a welded connection, but with the advantage of easy replacement of
the
lip wear segments 60 by unbolting the worn segments and bolting on new or
refurbished segments in their place.
[0030] Each segment 60 includes at least one wear-indicating hole 90 to
indicate the extent of wear and signal the operator to replace the lip wear
segments
at a suitable time to avoid damaging or wearing into the base plate. The wear-
indicating hole 90 comprises a relatively small aperture extending through or
partially through the lip segment 60 at a suitable position forwardly of the
horizontal
channel 76. For example, the hole 90 may be positioned near the rearward edge
of
the arcuate upper surface of the wear element. The hole 90 includes a visual
indicator 92 which becomes visible when the wear element has worn to a
predetermined level. For example, the visual indicator 92 may comprise a
texture or
color transition within the interior of the hole which becomes visible when
the
surrounding metal has worn to a predetermined extent or a different hole
diameter
which becomes visible at this time.
[0031] The cross sectional configuration of the lip wear segments 60 makes
them at least partially-self-sharpening. The arcuate upper surface 64 tends to
wear
at a generally even rate, resulting in the segment maintaining a substantially
constant profile for much of its useful life.
[0032] The lower flanges of the lip wear segments 60 preferably include shoe
elements 94 to provide additional resistance to wear. These shoes 94 comprise
thickened portions of the lower flange, which may be conveniently provided at
the
bolt hole positions 56. As seen in Figures 4 and 6, the shoes 94 protrude
downwardly from the bucket to elevate the lip segments 60 above the ground to
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minimize wear of the base plate 30 and other system components including the
bucket.
[0033] The lip wear segments 60 are provided in varying widths to
accommodate buckets of different sizes, As well, the segments maybe provided
in
different parallelogram shapes, including rectangular, to accommodate
different lead
lengths of the base plate associated with the segments. The segments may
protrude laterally outwardly from the wing segments 44, thus permitting the
use of
standard size segments 60 to accommodate a wide range of bucket sizes, as the
segments 60 do not have to precisely fit the bucket width.
(0034j It is contemplated that base plates 30 v~rith wing segments 44 welded
in place, along with multiple lip wear segments 60, may be provided to mine
operators for attachment by welding and bolting as required to their existing
buckets. The assembly of these elements may be carried out at the mine site.
[0035] Figure 7 illustrates another version of the lip wear segment 60. In
this
version, the upper surface of the segment includes broad scallop-shaped
recesses
100 which extend longitudinally from the front edge of the segment 60. The
scalloped recesses 100 are rectangular in plan view, and have a curved bottom
102.
The recesses 100 provide an enhanced scooping action which is useful in some
applications.
[0036] The present invention has been described by way of a detailed
description of an embodiment thereof. However, it will be seen by those
skilled in
the art to which this invention relates that numerous and varied departures
from the
embodiment described herein may be made, without departing from the scope and
essential nature of the present invention, including without limitation any
mechanical
and functional equivalent of any component, element or part described herein.
