Excavator bucket top assembly

An excavator bucket top assembly can be completed as an assembly before being attached to other components to form an excavator bucket. The top assembly includes a flat bottom plate and a top plate with two bends, each having relatively simple geometry for ease of manufacturing. Two hinge plates penetrate through the top plate and are joined to both the bottom plate and the top plate. The top assembly includes strategically positioned, continuous weld joints to avoid weld starts and stops that create stress risers. The top assembly produces a torque tube which is stiff and resistant to fatigue.

TECHNICAL FIELD

The field of this invention is excavator buckets, and more specifically top assemblies or hinge assemblies for excavator buckets.

BACKGROUND

Excavators, such as the one illustrated in U.S. Pat. No. 6,865,464, can be used in a wide variety of applications: in the construction industry to prepare building sites, in mining to load ore-laden material into trucks or onto conveyors, in road building to make cuts through hillsides for new road beds, in pipe laying and utility work to dig trenches. In all of these operations, excavators employ buckets to penetrate into material in the ground or in a pile, to scoop the material, and then to dump it. The bucket is the implement at the center of performing these tasks.

Excavator buckets are subjected to extreme loads and wear. An excavator bucket on a large excavator could be used to penetrate into extremely hard and dense material such as loosely shot or fractured granite. For this kind of duty, an excavator bucket requires high performance steels and a specialized construction to withstand both the high shock loads, and the extreme abrasive wear. Besides withstanding these maximum load cases and the abrasive environment, an excavator bucket must also be strong enough to endure many thousands, or in some cases, millions of cycles. (A cycle is each repetition of penetrating into the material, scooping, and dumping.) So an excavator bucket also requires resistance to fatigue wear and failure.

If an excavator bucket fails, replacement of the bucket can amount to a great expense in parts and labor. In addition, replacing a bucket will cause the excavator to sit idle and its productivity to decline, resulting in further costs. Besides idling the excavator, a bucket failure can also idle other machines in an integrated operation, such as haul trucks and crushers, further increasing the losses. Thus, a reliable excavator bucket that lasts through many cycles without breaking can be an important requirement for owners of excavator machines.

An excavator bucket can be expensive and difficult to manufacture because of its size and weight and other factors. Excavator buckets are typically constructed as weldments of more than a dozen pieces of plate steel. A bucket for a large, 60 metric ton excavator, for example, can be about 2 meters tall and 2 meters wide, weighing about 5 metric tons. Manipulating these large and heavy pieces of plate steel to align them to one another, and then correctly performing the welds can be a difficult and expensive task. A bucket design which requires a large number of pieces and multiple welds can add to the costs.

Thus, there are many demands affecting the design of an excavator bucket. The design must result in a bucket which exhibits the appropriate performance characteristics of resistance to high loads, abrasion, and fatigue, and which can also be manufactured in an economical manner. To produce a competitive bucket design, a designer must identify design features and techniques to satisfy and balance all of these demands.

SUMMARY

This invention relates to an improved design of a top assembly for an excavator bucket, which satisfies performance and manufacturability demands on the design, resulting in a bucket that is both resistant to failure, and economical to manufacture.

DETAILED DESCRIPTION

FIGS. 1 and 2depict an excavator bucket10having a bottom section20and a curved heel section30. Normal to the bottom section20and heel section30are two side sections40and50. The bottom section20includes a base edge21on which are mounted several adapters, tips, and base edge protectors, which are commonly referred to as ground engaging tools, or GET. One or more steel plates forming a part of the bottom section20may be joined to a wrapper31which forms a part of the heel section30. Each side section40,50includes a side plate41,51, a side bar42,52, and a side wear plate43,53. Different basic bucket elements and structure may be used to form the bucket10, as will be apparent to those of ordinary skill in this art.

Joining the heel section30and the side sections40,50is the top assembly (sometimes called hinge assembly)100. The top assembly includes a top plate110, a bottom plate120, and a pair of hinge plates130,140.

FIG. 1depicts the top assembly100in an assembled state and joined with the rest of the bucket10. In this view, the top plate110and hinge plates130,140are visible, but the top plate110obscures the view of the remaining top assembly100structure. InFIG. 2, the top plate110has been removed to reveal the underlying structure.FIG. 3is a sectional view taken through one of the hinge plates130,140.FIG. 4is a sectional view taken through the center of the bucket10.

The hinge plate130includes two bores131and132. Likewise, hinge plate140includes two bores141and142. Bores131and141are axially aligned and will support a stick pin that passes through the stick of the excavator. Bores132and142are axially aligned and will support a linkage pin that passes through the power link of the excavator which causes the bucket's curling motion about the stick pin. Thus, the hinge plates130,140form two sets of two axially aligned bores (131and141form a first set of two axially aligned bores, and132and142form a second set of two axially aligned bores).

Elements of the top assembly100cooperate to form a torque tube150. Torque tube150is designed to transfer torque from its middle section to its ends. The torque tube150functions to transfer “curling” torque about the center of the stick pin created by the power link and linkage pin, to the side sections40,50and the rest of the bucket10. When the bucket base edge21penetrates into material, the force propelling the base edge is transferred to the base edge in part by this torsional force created about the stick pin by the power link. In addition to torque, a variety of other load paths exist through the torque tube150. The torque tube150must be capable of transferring all of these large sustained and shock loads and torques. The torque tube is formed in part through joining the top plate110, bottom plate120, and hinge plates130,140to form a rigid, tube-like structure.

The top plate110defines a top surface111, a bottom surface112, a front edge113, and a rear edge114. The bottom plate120defines a top surface121, a bottom surface122, a front edge123, and a rear edge124. The bottom surface112and the top surface121are part of the inside surfaces of the generally enclosed torque tube150. The top surface111and the bottom surface122are part of the outside surfaces of the torque tube150.

The bottom plate120is formed from flat steel plate stock. For ease of manufacturing, the bottom plate120may not include any bends, nor any relatively complex cuts or shapes formed in it.

The top plate110is also formed from flat steel plate stock. The top plate110may include two bends, with a first bend having an included angle of approximately 105-125°, and more specifically approximately 115°, and a second bend having an included angle of approximately 100-120°, and more specifically approximately 110°. Each bend is approximately parallel to the front edge113of the top plate110. Each of the included angles faces toward the bottom plate120when assembled to help form the enclosed, tube-like structure of torque tube150. The outside surface profile of torque tube150created by these bends in top plate110helps the torque tube to be effectively positioned relative to certain existing, traditional quick couplers which may be used to attach bucket10to an excavator. The top plate110may easily be formed by first cutting its shape from plate stock, and then by creating the bends in a brake press or other type of press. Although the top plate may include two bends, it is still relatively easy to manufacture because it does not require any complex shapes or machining.

The assembly of top assembly100can begin by attaching hinge plates130,140to bottom plate120so that the hinge plates are parallel to one another and normal to the bottom plate. Each of the hinge plates includes a flat bottom edge133,143which butts against and is welded to the top surface121of bottom plate120. One of these weld joints is illustrated inFIG. 4with the reference character A. Each of the flat bottom edges133,143is approximately the same length as the distance between the front edge123to the rear edge124. Thus, the hinge plate130,140to bottom plate120butt joint extends approximately from the front edge123to the rear edge124. Advantageously, the butt joint need not extend beyond the rear edge124(as it does in some prior art designs where the hinge plates130,140also are joined to the wrapper31) in order to permit joining the hinge plates130,140to bottom plate120in an assembly which can be fully completed before being joined to the rest of bucket10.

Optional rib or ribs160may be included between hinge plates130,140and bottom plate120. The rib160may reinforce the connection between the hinge plates130,140and the bottom plate120, add stiffness to the torque tube150, as well as aid in maintaining alignment during welding and assembly. Both the hinge plates130,140and the rib160may include a slot cut in each—a portion of the rib fitting into the slot in each hinge plate, and vise versa—forming an interlocking halved joint therebetween. The rib160may be welded to the hinge plates130,140and to the bottom plate120around the same time as welding between the hinge plates and the bottom plate.

Hinge plates130,140may pass through and divide the top plate110. This allows hinge plates130,140to be welded to the bottom plate120as well as the top plate110, forming a stronger and stiffer torque tube150. Some prior art designs do not have hinge plates which are welded to both a top plate and a bottom plate, having instead hinge plates which are only welded to a top plate, which results in a weaker torque tube. Hinge plates130,140may divide the top plate110into three separate segments110a,110b, and110c. Segments110aand110care outboard of the hinge plates, meaning they are between one of the hinge plates and one of the sides of the bucket10. Segment110bis inboard of the hinge plates, or between the two hinge plates in the middle of the bucket10. The hinge plates120,130and segments110a,110b, and110care welded at a weld joint formed at their intersection and along the top surface111. One of these weld joints is illustrated inFIG. 4with the reference character B.

Top plate110and bottom plate120are joined to each other along a first and a second weld joint. A first weld joint may be formed at the intersection of the rear edge114of top plate110and the bottom plate120, along the top surface121. This weld joint is illustrated inFIG. 4with the reference character C. The bottom plate120may overlap the top plate110(i.e. the bottom plate extends further than the intersection of the top plate and bottom plate, and the top plate terminates at the intersection) to permit this joint. Because the rear edge114is joined to the bottom plate120, and does not extend further to intersect or join with wrapper31, the assembly between the top plate110and bottom plate120can be completed before the top assembly100is joined to the remainder of bucket10.

A second weld joint may be formed at the intersection of the front edge123with the top plate110, along the bottom surface112. This weld joint is illustrated inFIG. 4with the reference character D. In order to make this joint, the top plate110may overlap the bottom plate120. This construction advantageously permits this weld joint to be made with a continuous, non-interrupted welding pass from one end of torque tube150to the other. In other prior art designs where the bottom plate120overlaps the top plate110, this weld joint is formed at this intersection but on the top surface121, and the weld joint is segmented or broken because it is interrupted by the hinge plates. It has been determined by the inventors that the breaks in this second weld joint result in weak areas, or stress risers, which are an important cause of bucket failures. By eliminating the weld starts and stops in this second weld joint, the stress risers are minimized and the bucket is stronger. This second weld joint resides in a high load path region of the torque tube150, so minimizing stress risers in this region is very beneficial.

The foregoing construction of the top assembly100permits it to be completely assembled as an independent module before attaching to the remaining components of the bucket. Constructing the top assembly100as an independent module can present several advantages. The many welds in the top assembly100can all be performed before attaching the remaining components of bucket10. The top assembly100is smaller and lighter than the entire bucket10so the top assembly is easier to move around and position, making these welds simpler to perform.

Bores131,132,141, and142formed in hinge plates130,140, typically require tight tolerances. Traditionally, these bores are formed through machining after the hinge plates have been fixed to the bucket. Because hinge plates130,140are completely assembled into the top assembly100, these bores131,132,141, and142can be machined after top assembly100is assembled, but before top assembly100is joined to the rest of the bucket. Positioning top assembly100on a boring machine for making these bores can be a much simpler task than positioning the entire bucket10on a boring machine, and a smaller boring machine may be used.

For manufacturing workflow, the top assembly100can be completed and then wait for the remaining components to be gathered together for assembly into the final bucket10. The top assembly100can even be designed to work as a top assembly for more than one size and/or type of bucket. So a single top assembly100can be constructed and then fit to different remaining components to form a variety of buckets.

After the top assembly100is assembled, it can be attached to the heel section30and side sections40,50. The wrapper31is welded to the bottom plate120. The side bars42,52include ears44,54, which overlap the ends of the torque tube150. The ends of torque tube150are welded to these ears44,54. A fully assembled bucket10is illustrated inFIG. 1.

INDUSTRIAL APPLICABILITY

The foregoing excavator bucket top assembly may be used in the construction of excavator buckets for use in many industries including construction and mining.