Excavating – Cable-operated – Scoop or bucket
Reexamination Certificate
1999-12-27
2001-05-29
Shackelford, H. (Department: 3671)
Excavating
Cable-operated
Scoop or bucket
C037S403000
Reexamination Certificate
active
06237260
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to the mining and material excavation arts and, more particularly, to a dragline bucket wherein the basket is releasably secured to the forward ring.
BACKGROUND OF THE INVENTION
Dragline buckets are commonly used as an effective means of excavating overburden and winning coal during surface mining operations. Examples of common types of prior art dragline buckets can be found in U.S. Pat. Nos. 5,575,092 to Smit, 5,307,571 and 4,944,102, both to Behlendorf et al., as well as in now expired U.S. Pat. Nos. 2,584,416 to Boehringer and 1,908,686 to Burke. Each of these dragline buckets generally include a front, or forward, ring-like portion having a plurality of teeth for digging into the ground and a rear, basket-like portion for holding the excavated materials. Typically, the two components are joined to form a unitary bucket using welds, rivets, or other substantially permanent joining techniques. This creates a long lasting, durable bond that ensures that the unitary bucket can withstand the rigors of the excavation process without the components detaching from each other.
While a dragline bucket of unitary construction is effective for its intended purpose, it does suffer from one very significant shortcoming. Specifically, in a dragline bucket of unitary construction, it is difficult to separate the forward ring from the basket in the event that damage occurs to either component during extensive excavation operations, or if one of the components fulfills its useful life prior to the exhaustion of the full service life of the opposite component. In the past, extensive metalworking processes, such as cutting welds or removing a plurality of rivets, have been required to separate the components. It should be appreciated that such operations are very labor intensive and time consuming. This is particularly evident when one considers the size of a typical dragline bucket which has a capacity on the order of 220 cubic yards or more. In many situations, this can lead to significant production downtime for the dragline operation.
Another difficulty with prior art buckets is that the forward ring and basket are commonly made of very thick and heavy sections of durable metal materials, such as steel. Of course, the goal in using such materials is to prolong the service life of the individual components. This is a primary concern when one considers the previously described difficulty encountered when repairing and maintaining a bucket of unitary construction. The use of heavy metal materials, however, is not without its deletarious side effects.
Specifically, these materials greatly increase the weight of the bucket. Of course, the greater the weight of the bucket, the less the weight of material that may be removed by a dragline of given power (i.e. a larger portion of the lifting capacity of the dragline is used to lift the bucket and as a consequence there is less capacity available for lifting material).
If the basket could be easily replaced, it would be possible to use thinner and/or lighter construction materials since component service life would not be the primary design consideration it is at present. When lighter materials are used in the construction of the bucket, a larger portion of the lifting capacity of the dragline is available to lift material won during the mining operation. As such, more material may be won in each pass of the bucket and overall mining efficiency may be greatly enhanced.
Thus, a need is identified for a dragline bucket that overcomes the above-described limitations of the prior art. The bucket would have a basket that is secured to a forward ring in a manner that allows for easy removal and replacement. In addition to improving the efficiency of the repair operation, the simplicity and ease of replacement would permit the use of thinner materials of less overall weight in fabricating the basket. Overall, the improved dragline bucket would result in a significant improvement over baskets formed as a unitary whole using welding, rivets, or other permanent joining techniques.
SUMMARY OF THE INVENTION
Accordingly, it is a primary object of the present invention to provide a dragline bucket having a basket that is releasably secured to the forward ring to permit the quick and efficient (1) attachment of the components to form the bucket, and (2) detachment of the components in the event repair or replacement of any component becomes necessary.
Another object of the present invention is to provide a dragline bucket that avoids the use of welds, rivets, or other types of permanent joining techniques to secure the forward ring to the basket, thereby facilitating the separation of the components forming the bucket for repair or replacement.
Still another object of the present invention is to provide a improved dragline bucket wherein the ease and efficiency of detachment of the releasable forward ring from the basket permits the use of thinner, less durable and, therefore, more light weight materials in fabricating the basket component.
Additional objects, advantages and other novel features of the invention will be set forth in part in the description that follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the foregoing and other objects, and in accordance with the purposes of the present invention as described herein, an improved dragline bucket is provided with a quick change basket. Advantageously, the quick change feature allows for the easy removal of the basket or forward ring if either is damaged during operation or otherwise in need of repair. Another advantage provided by this improvement feature is that the basket component may be fabricated of thinner materials, if desired, thereby resulting in a lighter bucket that effectively reserves a greater proportion of the crane's lifting capacity for the stripping of overburden. This improves the overall efficiency of the excavating operation.
In the preferred embodiment, the dragline bucket includes a forward ring having an arch, a first cheek plate, a second cheek plate, and a bottom wall. Each of the components are joined together using any suitable metal joining techniques, such as by welding. The bottom wall of the forward ring carries a plurality of forwardly projecting teeth for digging into the material being excavated, such as the overburden in a surface mining operation.
The dragline bucket also includes a basket portion. The basket has an open front end and includes a lower wall, a pair of opposed sidewalls, and a rear wall. These walls cooperate to receive and hold the material won during the mining or excavation process.
The cheek plates carry means for receiving the forward margins of the sidewalls of the basket. In the preferred embodiment, the receiving means take the form of one or more pairs of mounting lugs projecting rearwardly from each cheek plate. Each pair of mounting lugs are provided with corresponding apertures. The lug pairs each form a channel for receiving the corresponding portion of the basket sidewall.
In accordance with an important aspect of the invention, the lug pairs on the forward ring allow for the quick attachment and detachment of the basket therefrom. To make the connection between the two components, a mounting lip on the bottom wall of the forward ring is placed in lapping relationship with a forward margin of the lower wall of the basket. The lip and forward margin of the lower wall have corresponding apertures through which releasable fasteners, such as mounting pins or bolts are inserted and locked in place. To complete the connection, the forward margins of the sidewalls are placed between the mounting lugs of the forward ring until apertures formed therein align and register with apertures formed in the reinf
King and Schickli PLLC
Shackelford H.
West Kentucky Steel Construction Company, Inc.
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