Patent Description:
Excavating machines, such as used in mining and construction operations, include buckets that are driven into the ground to gather a load of earthen material. The bucket is generally defined by a rear wall, a bottom wall and sidewalls to define a cavity with an open front for receiving the excavated material. The front edge of the bottom wall is provided with a lip on which ground engaging tools such as teeth, adapters and/or shrouds are generally attached to protect the lip against wear and to better break up the ground during digging. The lips are either formed of plate steel (which are called plate lips) or by a casting process (which are called cast lips). Either style of lip is welded into the bucket, i.e., to the front edge of the bottom wall and to the lower, front corners of each sidewall.

Cast lips are generally used on larger excavating machines such as dragline machines, cable shovels, face shovels, and hydraulic excavators. These lips are large steel structural members able to withstand the impact and other heavy loading experienced as the bucket is driven through the ground, resist undue wearing caused by the high abrasion environment, and securely support and hold the ground engagement tools in place for efficient digging. Accordingly, cast lips tend to be very heavy, which reduces the load each bucket can gather in each digging cycle. That is, excavating machines are designed for certain maximum loads, which include the weight of the excavated material as well as the weight of the bucket.

Existing lips typically have a structure that resists the many loads encountered in a digging operation and tends to carry the cantilevered tooth loads in torsion. The lips, however, tend to be massive and heavy to survive the very large loads and high abrasion environments commonly encountered in a digging operation and particularly in many mines. Mining and other excavating machines are constructed to lift loads up to a certain specified level. The more weight that exists in the lip, wear parts and other components of the bucket, the smaller the maximum payload that can be achieved by the bucket. The great size and weight also tends to increase manufacturing difficulties and cost of cast lips.

The present invention relates to a lip for an excavating bucket according to claim <NUM>.

Thus, the lip of the instant case has a reduced weight that provides the requisite strength and durability needed for satisfactory operation and provides resistance to heavy loading during use. The one or more recesses are designed for an advantageous weight-savings construction.

Thanks to the features of the characterizing portion of claim <NUM>, the lip of the instant case distinguishes over the teaching of <CIT> by its technical effect solving the problem of ensuring an advantageous weight-savings construction.

In another aspect of the invention, the total collective volume of the recesses is at least about <NUM>%, or more, of the total volume of the lip including the volume of the recesses.

The invention also relates to an excavating bucket according to claim <NUM>.

The present invention pertains to a lip for excavating buckets such as used with dragline machines, cable shovels, face shovels, hydraulic excavators and the like. The lip includes a dual beam construction and recessed portions to reduce the lip weight while maintaining the needed strength and resistance to bending and twisting.

A lip <NUM> in <FIG> in accordance with the present invention is welded at a back face <NUM> and along wings or ears <NUM> to bucket body <NUM>. Lip <NUM> has an elongate construction extending between the opposite sidewalls of the bucket body <NUM>. In this application, due to the elongated nature of the lip, the length of the lip is considered the long dimension that extends between the sidewalls of the bucket, even though this dimension is sometimes referred in the industry as the bucket or lip width. The lip includes a set of noses <NUM> spaced along the lip length and extending forward of the main lip structure for mounting ground engaging tools. Lip <NUM> is more fully illustrated in <FIG>.

Lip <NUM> includes a rear side <NUM> with rear face <NUM>, a front side <NUM>, and opposite ends <NUM>, <NUM>. Front side <NUM> defines a mounting portion <NUM>. Mounting portion <NUM> forward of beam <NUM> comprises a series of spaced apart noses <NUM>. Nases <NUM> receive ground engaging tools such as intermediate adapters or points (not shown) that separate material and direct the material into the bucket while protecting the lip. Noses on the mounting portion are separated by mounting areas <NUM> for attaching additional ground engaging tools such as shrouds (not shown). Lip <NUM> is preferably a cast lip, though it could be formed of parts (preferably cast parts) welded together.

In the illustrated embodiment, lip <NUM> is a stepped lip such that the front side <NUM> is stepped forward toward the center so that the noses <NUM> closer to the center of the lip are farther forward than those closer to ends <NUM>, <NUM> with portions between the noses extending generally along the length of the lip. A lip in accordance with the present invention, though, could have a spade configuration with intermediate portions between the noses inclined to the length of the lip, or reversed step or reverse spade configurations. Further, although lip <NUM> is shown as linear in front view, it could be bowed or angled vertically across its length, and/or include ends that curve upward.

A support structure <NUM> of the lip is rearward of and supports mounting portion <NUM>. Support structure <NUM> is formed to resist all kinds of loads and turning and bending forces encountered during a digging operation. In the present invention, members forming the support structure include a front beam <NUM> and a rear beam <NUM> extending along the length of the lip with at least one recess between the two beams. Conventional lips are formed with a single beam structure to resist the very high loads in a digging operation, particularly the large mining machines. While the single beam structure provides adequate strength and support, the lips tend to be massive and heavy. Some existing lips have recesses, but the weight savings is limited due to the mass that has been required to adequately counter the high loads.

Ribs <NUM> preferably extend between beams <NUM>, <NUM> to better couple the beams and transfer loads from the noses <NUM> to the bucket. The ribs subdivide the space between the beams to define a set of recesses <NUM> between beams <NUM>, <NUM>. Beams <NUM>, <NUM> and ribs <NUM> are of a substantial depth or thickness relative to the lip along recesses <NUM>. Recesses are defined by rear surface <NUM> of front beam <NUM> and front surface <NUM> of rear beam <NUM>, and the side surfaces of ribs <NUM>.

Beams <NUM> and <NUM> are free of substantial or sudden changes in dimension, and are generally continuous between ends <NUM> and <NUM>; though they may terminate prior to the actual ends. Superficial changes in the beam structure are possible so long as the primary bulk of each beam as a generally continuous and uninterrupted extension along the length of the lip. The beam can incorporate curves in extending across the lip. Curves in the beam preferably coincide with the intersection of a rib to compensate for stress concentrations induced by the curve. This generally continuous and uninterrupted construction gives the lip a dual beam construction to resist heaving loads and twisting despite the presence of recesses <NUM>. Various changes in beam configuration are possible without departing from the invention. For example, the depth of beam <NUM> may taper out before the ends. Alternatively, the beams may taper from the ends <NUM>, <NUM> towards the center of the lip. In the illustrated embodiment ends <NUM>, <NUM> have wings <NUM> for welding to sidewalls <NUM> of the bucket at upper surface <NUM> and rear surface <NUM>. Wings <NUM>, in this embodiment, extend above the main portion of the lip.

Preferably, lip <NUM> is generally smooth and continuous along its upper surface <NUM> for unobstructed loading of the earthen material into the bucket. The lower surface <NUM> of the lip is structured for weight savings with the beams <NUM>, <NUM>, recesses <NUM>, and ribs <NUM>. Nevertheless, upper surface <NUM> and lower surface <NUM> could have other configurations. For example, recesses <NUM> are preferably open, but they could be enclosed by a plate welded over the bottom, e.g., between beams <NUM>, <NUM>.

The top surface <NUM> of lip <NUM> can be considered as a panel support structure 28A that couples front beam <NUM> to rear beam <NUM>. Ribs <NUM> also preferably join the beams and resist axial and twisting forces as the bucket moves forward through the excavated material. Additionally, one or more panels <NUM> can be secured to and connect ribs <NUM> and beams <NUM>, <NUM> along the underside of the lip to enclose recesses <NUM> (<FIG>). The panel or panels provide additional stiffness and support to the lip, and absorb side forces applied to the front of the structure as torsion and warping. The lip structure can be considered a honeycomb with square cells and one side of the cells covered by a structural sheet. The structure also resembles a semi-monocoque construction as compared to the massive single beam constructions of existing lips.

In a preferred embodiment, front beam <NUM> is oriented forward in the lip <NUM>, i.e., just rearward of mounting portion <NUM> to provide greater strength and stability to the wear parts. Front surface <NUM> of front beam <NUM> slopes upward from supporting structure <NUM> to define a smooth transition between beam <NUM> and ground engaging tool mounts. The beam <NUM> generally has a greater depth than mounting portion <NUM>. Rear surface <NUM> of front beam <NUM> transitions to recessed portion <NUM>. The bottom surface <NUM> of beam <NUM> also preferably slopes rearward to reduce wearing du ring digging, but could have different orientations.

Since the illustrated embodiment is a stepped lip, front beam <NUM> is preferably laterally bowed such that the central section <NUM> is farther forward than end sections <NUM>, <NUM> (<FIG>). With this construction, the front beam could have a generally continual forward bowing as shown in <FIG>. Alternatively, the front beam could have a pair of broad S-shaped bends to define the central forward bowing of the front beam (not shown). In this variation, the bends are preferably generally in line with the noses and the ribs. Front beam <NUM> can be linear with a straight lip, or bowed in the opposite direction with a reverse spade lip. Front beam <NUM> could have a curved configuration with the ends higher than the center of the lip when viewed from the front. The lip can take on various shapes as desired regardless of the particular kind of lip involved.

Rear beam <NUM> preferably has a reduced depth compared to front beam <NUM> for enhanced weight savings, improved penetration, reduced wearing, and ta match the front of the bucket bottom wall. Rear beam <NUM> has a front surface <NUM> that slopes upward to recessed portion <NUM>. Rear surface <NUM> is generally vertical to match the front of the bucket bottom wall to which it is welded along with the rear face <NUM> of wings <NUM> but can include features such as bevels to receive weld material for attaching the lip to the bucket. Rear beam <NUM> is preferably linear to accommodate the welding to bottom wall, but could be non-linear to facilitate attachments ta other bottom wall configurations.

Ribs <NUM> extend laterally (i.e., front to back) between front beam <NUM> and rear beam <NUM> for increased strength and stiffness of the lip. Ribs <NUM> are relatively thin supports that intersect rear surface <NUM> of front beam <NUM> and front surface <NUM> of rear beam <NUM>. Preferably, ribs <NUM> taper in depth rearward to gradually slope from the greater depth of front beam <NUM> to the lesser depth of rear beam <NUM>. This taper of the ribs reduces weight, improves penetration and lessens wearing. As seen in <FIG>, ribs <NUM> are preferably centered behind noses <NUM> to best transfer the bending moment to the rear beam <NUM>, but they could have other positions or additional ribs in other positions could be provided. Ribs <NUM> can diverge outward toward the lip ends <NUM>, <NUM> as they extend from the front beam to the rear beam, but they could be parallel to each other or converging in a rearward direction. The diverging ribs reduce the stress in the lip as the ribs distribute the applied loads out to the bucket. A transverse axis TA extends from the lip front to the rear of the lip perpendicular to the rear beam <NUM> and the ribs define a longitudinal rib axis RA. In the illustrated embodiment he rib axis inclined to the lip axis at an angle α of at least <NUM> degrees. In an alternative embodiment, a subset of ribs <NUM> diverge outward as they extend from the front beam to the rear beam and the balance of the ribs do net diverge.

The configuration of support structure <NUM> also allows ribs <NUM> to be narrower than the width of the nose <NUM> of mounting portion <NUM>. Conventional lips have substantial ribs with widths exceeding that of the noses they support. Using a narrow rib that can provide adequate support and coupling of the front and rear beams in a way that significantly reduces the mass of the lip. Nevertheless, the ribs could have other orientations (e.g., parallel to the axes of the noses, inclined in opposite directions, and the like) and could have other configurations besides generally linear. Also, in this embodiment, wings <NUM> also extend between beams <NUM>, <NUM> at ends <NUM>, <NUM> and function in part similarly to ribs <NUM>. The wings and ribs are collectively referred to as lateral supports.

Recessed portions <NUM> between beams <NUM> and <NUM> are thinner than adjacent support members and comprise a large portion of the lip. In the illustrated example, the recesses define the entire portion between beams <NUM>, <NUM> except for ribs <NUM> and wings <NUM>. As can be seen, the lip has a substantially reduced thickness (or depth) than either of the beams <NUM>, <NUM>. In this example, the centers of the recesses have depths that are less than <NUM>% of the depth at the center of the front beam <NUM>. Similarly, the thickness (or depth) at the center of the recesses is about <NUM>% of the thickness at the center of the rear beam <NUM>. Of course, other relative thicknesses could be used. Recesses <NUM> can be domed so that they taper in thickness from the edges to the center.

The recesses of support structure <NUM> make up a significant portion of the lip in order to achieve the desired weight savings. In certain preferred embodiments of the present invention, the weight-savings can be maximized beyond prior lips. For example, in these certain preferred embodiments, the total collective volume of the recesses in the lip is at least about <NUM>% of the total volume of the lip including the volume of the recesses. In one preferred embodiment, the volume of the recesses is about <NUM>% of the total volume of the lip. For example, the total volume of the lip is about <NUM> cubic meters, and the total collective volume of the recesses is about <NUM> cubic meters. The inventive lip can, of course, be used in lips of many different sizes and types. As a comparison, in one prior lip of comparable size, the volume of the recesses is about <NUM>% of the total volume of the lip (including the volume of the recesses). For example, the prier lip volume of <NUM> cubic meters, and the volume of the recesses is about <NUM> cubic meters. In other prior lips, the volume of the recesses range from <NUM>% to <NUM>%. The prior lips lack the maximized weight-savings construction of the present invention and requires more mass and less recesses to maintain the desired strength. The invention, though, is not dependent on having a total collective volume of the recesses being at least <NUM>% of the total volume of the lip (including the volume of the recesses). In some uses and sizes, a lip in accordance with the present invention (e.g., a lip with front and rear beams separated by one or more recesses) can have a construction where the total collective volume of the recesses is much less than <NUM>% of the total volume of the lip (including the volume of the recesses).

Claim 1:
A lip (<NUM>) for an excavating bucket (<NUM>) comprising a mounting portion (<NUM>) for mounting ground engaging tools and a supporting portion (<NUM>) rearward of the mounting portion (<NUM>), the supporting portion (<NUM>) including one or more recesses (<NUM>), characterized in that the one or more recesses (<NUM>) are collectively at least about <NUM> percent of the total volume of the lip (<NUM>) including the total collective volume of the recesses (<NUM>) and the lip including, to each side of the one or more recesses (<NUM>), a front beam (<NUM>) and a rear beam (<NUM>) which has a reduced depth compared to the front beam (<NUM>).