CA2445795C - Replaceable wear lip for an excavator bucket - Google Patents

Abstract

A replaceable lip protector is provided for covering the exposed lower edge of a prow-shaped lead of an excavator bucket. The lead attaches to the lower front plate of the excavator bucket and extends the reach of the bucket. The protector comprises multiple segments which are parallelogram in shape, with a horizontal channel recessed into the rear face for tightly fitting into the forward edge of the lead. A mechanical fastening system joins the segments to the lead in a fashion which permits individual segments to be removed and replaced, for example when they are worn. Wear indicator elements indicates to the operator that replacement is needed.

Description

_1_ 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 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 -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 -q.-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.

-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 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.

(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 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.

(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 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 -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 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.

Claims

CLAIM:

1. An excavator bucket assembly comprising a bucket having a lower lip and a replaceable lead assembly for fastening to said lip, said lead assembly comprising a generally prow-shaped base plate having a rear edge for abutting against and fastening to said lower lip a chevron-shaped forward edge comprising angled left and right leading edges meeting in a central tip, and a plurality of replaceable lip protectors for releasable attachment to the leading edge of said base plate in side by side generally abutting relationship, said protectors each having a rear surface having a substantially horizontal channel opening to said rear surface to receive said forward edge of said base plate and mechanical fastening means to releasably connect said protectors to said base plate, said protectors each having a substantially parallelogram shape characterized by non-right angles, and replaceable corner members defining the lateral sides of said assembly, each of said corner members being generally L-shaped in section and including a forwardly-protruding horizontal plate for fitting into a horizontal channel of a corresponding of said protectors, wherein said corresponding protector when engaged to said horizontal plate may overhang said plate laterally.