Swing Gear Assembly and Method for Manufacturing the Same

A swing gear set for a large scale or heavy machine can be produced from components of a swing gear set including an internal gear ring assembled from plurality of internal toothed segments and/or an external gear ring assembled from a plurality of external toothed segments. The internal toothed segments and/or the external toothed segments are produced by bisecting a metal block in the shape of a rectangular prism into first and second intermediate blanks. The metal block can be produced by a forging process and the intermediate blanks can be machined by various machining process to produce the finished internal and external toothed segments.

TECHNICAL FIELD

This patent disclosure relates generally to a swing gear assembly to provide a rotatable interface between a rotatable upper structure and a lower base of a large scale or heavy machine, and more particular the disclosure relates to a method of manufacturing gear segments from which the swing gear assembly can be assembled.

BACKGROUND

Large scale and heavy machines like dragline excavators, rope shovels, and rotary cargo container cranes are used in operations like mining, material excavation, and cargo transportation. These machines may include an extended truss assembly from which a work implement can be suspended. For example, a dragline excavator can include a dragline bucket suspended several meters forward of the machine. The dragline bucket can be lowered to the excavation surface and drawn toward the machine via wire ropes or chains so that excavation material is deposited into the dragline bucket. The machines can perform a swing-and-dump maneuver that swings the truss assembly with respect to a vertical axis of the machine to deposit the excavated material or, in the case of a rotary cargo container crane, the cargo container.

To enable the swing-and-dump maneuver, the machine can have a swing assembly including in particular a swing gear assembly that functions as the interface between and joins an upper structure of the machine from which the truss assembly is suspended to a lower base on which the machine is supported on the work surface. The swing gear assembly may include an internal gear ring or an external gear ring that meshes with and can be driven by a round pinon to rotate the upper structure. In the example of these large machines like dragline excavators where the truss assembly may extend a hundred meters or more and the bucket may hold several tons of material, it will be appreciated that the swing gear assembly can be several meters in diameter and can be made from high strength materials like steel or iron. Moreover, because of their size, many types of these heavy machines are configured to be built onsite from components that must be transported to the needed location. Accordingly, to facilitate manufacture and transportation of the swing gear assembly, it may be configured as a segmented gear assembly in which the intermeshing gears are assembled from a plurality of individual gear segments in the form of partial angular arcs that can be combined to provide the entire circular circumference of the swing gear assembly.

The present disclosure is directed to gear segments and methods of producing gear segments as described above for forming a swing gear assembly for a large scale or heavy duty machine like a dragline excavator.

SUMMARY

The disclosure describes, in one aspect, a method of producing a gear set for a large scale or heavy machine. The method involves forging a metal block from raw material that has the shape of a rectangular prism including a first lengthwise face and a second lengthwise face and an upper face and a lower face. The metal block is bisected into a first intermediate blank and a second intermediate blank by a diagonal cut disposed between the upper face and the lower face. A plurality of arranged teeth is milled into the first lengthwise face of the first intermediate blank to produce one of an internal toothed segment and an external toothed segment. Similarly, a plurality of arranged teeth is milled into the second lengthwise face of the second intermediate blank to produce one of an internal toothed segment and an external toothed segment.

In another aspect, the disclosure describes a gear set including a gear ring with a plurality of teeth. The gear ring may include a first toothed segment having a plurality of gear teeth disposed into a first lengthwise face of a first intermediate blank from which one of the plurality of the toothed segments is machined. The gear ring may also include a second toothed segment having a plurality of gear teeth disposed into a second lengthwise face of a second intermediate blank from which the one of the plurality of the toothed segments is machined. The first intermediate blank and the second intermediate blank are commonly bisected from a metal block.

In another aspect, the disclosure describes a gear ring assembled from a plurality of gear segments. Each gear segment includes an upper face and a lower face parallel to and spaced apart from the upper face. Each gear segment further includes a lengthwise face extending between the upper face and the lower face with a plurality of teeth disposed therein. Each gear segment further includes a lengthwise edge parallel to and spaced apart from the lengthwise face and extending partially between the upper face and the lower face. The plurality of teeth is selected from the group comprising internal teeth concavely disposed in the lengthwise face and a plurality of external teeth convexly disposed in the lengthwise face.

DETAILED DESCRIPTION

This disclosure relates to a swing gear assembly for rotatably joining an upper structure to a lower base on large scale or heavy machines used for earthwork operations, large scale construction operations, or cargo handling. Referring toFIG. 1, wherein like reference numbers refer to like elements, there is illustrated an example of a heavy machine in the embodiment of a dragline excavator100used in earthwork operations such as material excavation and surface mining. Aspects of the disclosure, however, are applicable to other large scale or heavy machines such as rope shovels, cranes, and other types of excavators. The illustrated embodiment of the dragline excavator100includes an upper structure102that is supported on and rotatable with respect to a lower base104. The upper structure102, which may also be referred to as a house or cabin, internally accommodates the motors or engines and the hoist and drag mechanisms for powering the operations of the dragline excavator100and which may include an operator's cab106located at front of the upper structure from where an operator can observe and control operation of the dragline excavator. The lower base104supports the upper structure102and contacts the work surface108or excavation surface.

Joined to and extending from the upper structure102can be a frame or truss assembly110which includes the truss components and rigging that support and maneuver a dragline bucket112. The dragline bucket112may be suspended from a boom114that extends upward and outward from the front of the upper structure102and can be maneuvered by various ropes, cables, or chains. For example, the dragline bucket112can be raised and lowered with respect to the work surface108by a hoist line116that extends along the boom114through a sheave118at the distal end of the boom and connects to a hoist coupler120on the dragline bucket112. The dragline bucket112can also be drawn horizontally over the excavation surface by a drag line122. In operation, for example, to remove overburden that may be located over the material of interest such as coal or other minerals, the dragline bucket112is lowered and penetrates into the work surface108via the hoist line116and drawn toward the upper structure102by the drag line122thereby gathering material in the bucket. The hoist line116and drag line122can be retracted and payed out by appropriate drums located in the upper structure102and which the lines are wound around. To support the boom114during movement of the dragline bucket112, the truss assembly110can also include a vertical brace124that extends upwardly from the upper structure102.

By way of example, the length of the boom114can be a hundred meters or more and the capacity of the bucket112can be a hundred tons or more of material. The loads on the hoist line116and drag line122are significant and can be on the order of hundreds of thousands of foot-pounds of tensile stress. The hoist and drag lines116,122can be made from high strength steels wires twisted into a helix and can have diameters on the order of twelve or more centimeters. Accordingly, to counterbalance hoisting and maneuvering of the dragline bucket112when loaded, the upper structure102that accommodates the hoist and drag machinery can weigh several hundred tons. Correspondingly, the length of the upper structure102can be thirty meters or greater and can have a correspondingly large width.

To traverse and maneuver the dragline excavator100over the work surface108, the lower base104can include appropriate propulsion devices126such as continuous tracks formed from a band of linked track plates that can translate with respect to the lower base104, thereby moving the upper structure102over the work surface108. In other embodiments, the propulsion devices126can be a walker or crawler unit wherein support feet or shoes can be eccentrically lifted and lowered with respect to the work surface108and thereby move the upper structure102forward or rearward over the work surface108. Although the embodiment of a dragline excavator100described herein is a type of mobile machine, aspects of the disclosure may also relate to large scale or heavy stationary or fixed machines, such as cargo cranes and the like.

One step in an excavation operation is a swing and dump operation. In this step, the upper structure102is pivoted with respect to the work surface108to move the dragline bucket112from the location where it has excavated material to a location where the dragline excavator100deposits the material for removal from the excavation site. For example, the material may be deposited on an in-site conveyor or a haul truck. To enable the dragline excavator100to conduct the swing and dump operation, the upper structure102is located on a swing platform128that is rotatably joined to the lower base104by a swing assembly130so that the upper structure102is rotatable relative to the lower base104about a vertical axis line132. The swing assembly130can include a roller bearing134that carries the load of the upper structure102while enabling relative rotational motion between the upper structure102and the lower base104with respect to the axis line132. Due to the size and weight of the upper structure102, it will be appreciated that the swing assembly130supports a significant load, possibly on the order of several hundred tons.

To drive rotation of the upper structure102with respect to the lower base104, the swing assembly130can be made from components of a gear set136on which the swing platform128is mounted and that can be operatively associated with a motor accommodated in the upper structure102. Referring toFIG. 2, the gear set136can include an internal gear ring140and/or an external gear ring142. In accordance with the disclosure, the internal and external gear rings140,142can be produced together by a common manufacturing operation and one or the other of the internal or external gear rings can be used in the swing assembly130on the dragline excavator100or similar machine. For reference, the internal gear ring140and the external gear ring are concentrically aligned around the axis line132that corresponds to the axis of rotation of the swing assembly130when installed on the dragline excavator. When assembled, either the internal gear ring140or the external gear ring142is fixed to the lower base104and can mesh with one or more pinions extending from the upper structure102and driven by an electric motor or other power source. The upper structure102therefore rotates around the axis line132so that the upper structure102swings with respect to the lower base104.

The internal gear ring140can be shaped as an annular ring and includes a plurality of radially inward directed internal teeth144and the external gear ring142can also be shaped as an annular ring and includes a plurality of radially outward directed external teeth146. The internal gear ring140and the external gear ring142can be spur gears wherein the internal teeth144and the external teeth146extend over the height of the ring-shaped internal gear ring140and external gear ring142respectively so as to be parallel with the axis line132. Further, the internal teeth144are circumferentially disposed about and spaced apart along the inner circular periphery of the internal gear ring140and the external teeth are circumferential disposed about and spaced apart along the outer circular periphery of the external gear ring142. In the illustrated embodiment, the internal teeth144and the external teeth146can have an involute profile to facilitate intermeshing and sliding contact with respect to the gear teeth on a round pinion that drives rotation of the swing gear assembly130. In other possible embodiments, however, the gear teeth may have other configurations such as helical.

Because of the size of the upper structure102including the truss assembly110, it should be appreciated that the gear set136should have a correspondingly large size. For example, the pitch diameter148of the internal and external gear rings140,142, which is indicated schematically by the arrow and which may represent the diametrical dimension extending between the approximate midpoints within the depth of engagement between diametrically opposite inner and external teeth144,146, can be on the order of twelve meters or more.

To facilitate manufacturing of the internal and external gear rings140,142, and to facilitate transportation in the case where the dragline excavator is assembled onsite, the swing assembly130can be a segmented gear assembly in which the internal gear ring140and the external gear ring142are assembled from a plurality of arcuate gear segments including an internal toothed segment150and an external toothed segment152. The arcuate-shaped internal toothed segments150can correspond to partial arcs that, when assembled together, complete the circumference of the internal gear ring140. Likewise, the arcuate-shaped external toothed segments152can correspond to partial arcs that, when assembled together, complete the circumference of the external gear ring142. The internal toothed segment150and the external toothed segment152can have various angular extensions, for example, 90° so that the internal gear ring140and the external gear ring142are made up of four identical internal toothed segments150and external toothed segments152respectively. However, other angular extensions are contemplated such that the internal gear ring140and the external gear ring142are made up of any suitable number of internal or external toothed segments150,152.

To manufacture the internal toothed segment150and/or the external toothed segment152, multiple segments may be produced from the same metal block via specific cuts and machining steps. For example, referring toFIG. 3, there is illustrated an exemplary metal block160that can be shaped as a rectangular cuboid or rectangular prism from which the segments can be formed. As a rectangular prism, the metal block160has a three-dimensional geometry and can include six quadrilateral faces with adjacent faces intersecting at right angles and arranged perpendicular to each other. The quadrilateral faces can be designated as a first lengthwise face162and a parallel second lengthwise face164that can correspond to the forward and rearward faces of the metal block160, a first end face166and a parallel second end face168that correspond to opposite lengthwise ends of the metal block160and define the width of the metal block between the first and second lengthwise faces162,164, and an upper face170and a parallel lower face172that define the vertical height of the metal block160. To produce internal and external toothed segments suitably sized for a dragline excavator, the metal block160may have a length on the order of two meters or more, a width between the first and second lengthwise faces162,164of one meter or more, and a height between the upper face170and the lower face172of thirty centimeters or more.

To provide sufficient strength characteristics to the internal and external toothed segments, the metal block160can be made from a suitable metal such as steel or iron. In an embodiment, the metal block160can be produced by a metalworking process and in particular formed from a forging process in which an initial quantity of metal produced as a casting or extruded ingot is compressed into the shape of the rectangular prism illustrated inFIG. 3. During the forging process, the metal is shaped by applied compressive forces, for example, by repeated strikes from a forging hammer or press and dies. The forging process plastically deforms the metal into the desired shape and can impart desirable strength characteristics and microstructural properties to the metal block160. To improve formability where the metal block160is made from steel or iron, the forging process may be hot forging process where the initial casting or ingot is heated to a highly elevated temperature. After the metal block160has been forged, it may be subjected to additional heat treating processes to impart desirable characteristics such as to improve machinability and strength. In addition to the forging process, in other embodiments of the disclosure, other metal forming processes can be used to form the metal block160including, for example, casting and extrusion.

Once the metal block160has been forged or otherwise shaped into the rectangular prism, the metal block is processed through additional machining steps to produce a first intermediate blank174and a second intermediate blank176. Referring toFIGS. 3 and 4, the first intermediate blank174and the second intermediate blank176can be identical in shape and size and can be formed by cutting the metal block160lengthwise between the upper face170and the lower face172. Because the cutting process results in dividing the metal block160into first and second intermediate blanks174,176of equal and congruent shape, size, and mass, it may be referred to as “bisecting” the metal block.

The metal block160can be cut178on a diagonal slant with respect to the first and second end faces166,168to bisect the metal block into the first and second intermediate blanks174,176. However, rather than making the diagonal cut178between the intersection of the first lengthwise face162and the upper face170and the intersection of the second lengthwise face164and the lower face172, the diagonal cut178can be offset rearward of the first lengthwise face162and offset forward of the second lengthwise face164. Accordingly, the diagonal cut178passes though the upper face170and the lower face172.

Because of the substantial size of the metal block160, an appropriate cutting process can be used such as, for example, a band saw or circular blade saw supported on a frame or table that may include rollers or slides to maneuver the metal block with respect to the blade. Other suitable cutting methods include but are not limited to electric discharge machining, laser cutting, and plasma cutting.

In an embodiment, to guide and facilitate the cutting process used to form the diagonal cut178, one or more guide grooves can be formed in the appropriate faces of the metal block160. For example, these may include a pair of lengthwise grooves180extending across the upper and lower faces170,172, respectively, between the first and second end faces166,168and parallel to the first and second lengthwise faces162,164. In addition, a pair of diagonal grooves182can be formed in the first and second end faces166,168, respectively, and that extends between the upper and lower faces170,172. The lengthwise grooves180and diagonal grooves182delineate and can guide the diagonal cut178to be made through the metal block160.

As a result of the diagonal cut178to bisect the metal block160into the first and second intermediate blanks174,176, the intermediate blanks respectively include a first slanted face184and a second slanted face186. The first and second slanted faces184,186made by the diagonal cut178extend at an inclined angle between the upper and lower faces170,172. Because of the angled orientation of the first and second slanted faces184,186, a substantial portion of the upper face170remains as part of the first intermediate blank174and a substantial portion of the lower face172remains part of the second intermediate blank176. The resulting first and second intermediate blanks174,176can be shaped as trapezoidal cuboids or prisms in that the remaining portions of the upper face170and the lower face172are parallel and the remaining portions of the first and second end faces166,168are parallel but the first and second lengthwise faces162,164are nonparallel with respect to the respective first and second slanted faces184,186.

To reduce weight of the finished internal and external toothed segments, excess material can be removed from the first and second intermediate blanks174,176. For example, referring toFIG. 4, triangular cuts188can be made into the metal block160at locations parallel to where the diagonal cuts178intersects the upper and lower faces170,172. The triangular cuts188can extend the length of the metal block160with respect to the first and second lengthwise faces162,164. The triangular cuts188can result in the removal of triangular-shaped wedges190of metal from the metal block160proximate both the upper face170and the lower face172. The triangular-shaped wedges190may become waste or scape metal for recycling.

Because of the triangular cuts188and removal of the triangular-shaped wedges190, the cross-section of the first and second intermediate blanks174,176can be that of a five-sided polygon in that each includes a lengthwise edge192formed by the triangular cut188. The lengthwise edges192can be parallel to the first and second lengthwise faces162,164and can extend the length of the metal block160between the first and second end faces166,168. Any suitable cutting technique can be used to form the triangular cut188including, for example, torch-cutting using a fuel and oxygen.

Additional machining and metalworking processes can be performed on the first and second intermediate blanks174,176to form the finished parts corresponding to the internal and external toothed segments150,152illustrated inFIGS. 5 and 6. By forming the finished internal and external toothed segments150,152from the intermediate blanks174,176, the finished segments are unitary, integral parts of sufficient strength and rigidity for the intended application.

For example, the plurality of internal teeth144of the internal toothed segment150may be machined into the first and/or second lengthwise faces162,164of the first and/or second intermediate blanks174,176. Likewise, the external teeth146of the external toothed segment142can be machined into the first and/or second lengthwise faces162,164of the first and/or second intermediate blanks174,176. Because the internal toothed segment150is only a partial arc of the circumference of the finished outer gear ring, the internal teeth144are arranged as a plurality of concavely arranged teeth194that curve inward into the internal toothed segment150. Similarly, the external teeth146are arranged as a plurality of convexly arranged teeth196that curve outwardly with respect to the external toothed segment152.

The internal teeth144associated with the plurality of concavely arranged teeth194and the external teeth146associated with the plurality of convexly arranged teeth196can be machine into the first and second lengthwise faces162,164of the respective first and second intermediate blanks174,176by a suitable machining process. For example, while hobbing with a hob cutting tool is a machining process often used to remove metal from a blank to form gear teeth, because of the size of the first and second intermediate blanks174,176and because the finished internal and external toothed segments150,152are only a partial arc of some degrees of the complete internal and external gear rings, other metal removing processes like broaching and milling may be used in addition or instead.

In an embodiment, to further reduce weight of the finished internal and external toothed segments150,152through the removal of excess material, a plurality of pockets198can be machined into the first and second intermediate blanks174,176. For example, a plurality of recesses or pockets198can be machined into the slanted face184of the first intermediate blank174corresponding to the internal toothed segment150generally in the axial direction by a peripheral milling process using a milling cutter. Another plurality of recesses or pockets198can be machined into the slanted face186of the second intermediate blank176corresponding to the external toothed segment152generally in an axial direction with a milling cutter. The plurality of pockets198, for example, in the illustrated embodiment four pockets, can be linearly spaced along the lengthwise edge192generally adjacent to the plurality of concavely arranged or convexly arranged teeth194,196and can have similar or dissimilar shapes.

Machining of the plurality of pockets198may define a plurality of structural supports200that are integrally fixed with respect to the finished internal and external toothed segments150,152and that linearly separate the plurality of pocket198with respect to the lengthwise dimension of the internal and external toothed segments. The structural supports200can extend towards and are generally orthogonal or perpendicular with respect to the lengthwise edge192and generally have a downward sloping configuration The structural supports200, which can be generally orthogonal or perpendicular to the plurality of concavely or convexly arranged teeth194,196, can radially brace the teeth as the inner and outer gear rings intermesh with the pinion that drives the swing assembly. The uppermost extension or surface of the plurality of structural supports200can correspond to the slanted faces184,186created by the diagonal cut178described above. Accordingly, the structural supports200are inclined downwardly as they extend to the lengthwise edge192of the respective internal and external toothed segments150,152. The downwardly sloped structural supports200can serve to direct or transfer forces or loads applied to the concavely or convexly arranged teeth194,196that the structural supports brace to the upper structure or lower base of the dragline excavator.

The plurality of pockets198can form a corresponding plurality of recessed bearing surfaces202into the internal and external toothed segments150,152that are generally parallel to the remaining portions of the upper face170and the lower face172. Disposed into the recessed bearing surfaces202can be one or more axial through holes204formed, for example, by drilling and adapted to receive threaded fasteners there through to secure the internal and external toothed segments150,152to the lower base of the dragline excavator. Locating the axial through holes204in the recessed bearing surfaces202created by the pockets198has an advantage of shortening the length of fasteners used to secure the toothed segments to the lower base of the dragline excavator as appropriate. Washers may be used to spread the load of the fasteners over the recessed bearing surfaces202. In addition to the axial through holes204, to facilitate lifting and installation of the internal toothed segment150and external toothed segment152, one or more threaded lifting holes206can be disposed at appropriate locations.

In a possible embodiment, to enable the arc-shaped internal gear segments150and the external gear segments152to be circumferentially aligned in an abutting arrangement and produce a circumferential circles associated with the internal gear ring and the external gear ring respectively, the first and second end faces166or168may be cut or milled at an angle between the lengthwise faces162,164and the lengthwise edge192. The first and second end faces166or168may be milled using an end mill or similar cutting tool.

INDUSTRIAL APPLICABILITY

Referring toFIG. 7, there is illustrated a schematic diagram of a series of metalworking steps and processes that can be conducted to form and finish a plurality of internal toothed segments and external toothed segments that can manufactured together and selected for assembly into a large diameter swing gear assembly. The different steps and processes physically alter the metal material at different stages to produce the finished part. The schematic diagram inFIG. 7is exemplary only, and the order of the individual steps and processes may change and particular steps and processes may be omitted or added. In addition toFIG. 7, the examples of metalworking and manufacturing processes will be explained with reference toFIGS. 3-4illustrating the metal block160andFIGS. 5-6illustrating the finished internal toothed segment150and finished external toothed segment152.

In an initial forming process300, raw metal material such as steel or iron is cast or extruded to form a raw casting or ingot302. Casting and extrusion are considered to be types of bulk forming processes as familiar to persons of skill in the art of metalworking. Casting involves heating the metallic raw material, for example, iron ore or steel, to molten liquid that is poured into a mold or cast and cooled until solid. In extrusion, hot metal may be pushed through a die defining a desired cross-sectional shape to produce an ingot. The solid metal assumes the form of the mold, cast or, in the case of extrusion, assume the cross-section of the die, as indicated by the casting or ingot302inFIG. 7.

In a subsequent forging process304, the casting or ingot302can be formed or worked to produce the metal block160in the shape of a rectangular prism. Forging may be considered a type of metal forming process in which the casting or ingot is further shaped by applying compressive forces to cause mechanical deformation. In forging and similar metal forming processes, the shape and physical properties of the metal work piece may be altered by physical deformation without removal of the metal material. The compressive forces may be applied by placing the casting or ingot in a die defining the desired shape and repeatedly striking the part, for example, with a forge press or power hammer. In an embodiment, the forging process304may be a hot forging process in which the casting or ingot is heated while being compressed to enable the microstructural grains or crystals of the metal to reform or adapt to the imparted shape. In addition to producing a desired shape, forging improves the strength of the metal through work hardening and alignment of molecules on microstructural scale. By way of example, the metal block160produced by the forging process304may be sized two or more meters in length by one or more meter in width by thirty centimeters or more in vertical height.

In an embodiment, the metal block160can undergo a heat treating process306in which the metal block is heated to an elevated temperature for a period of time and cooled. Heat treatment is a type of treatment process that alters the microstructural properties of the metal block160to improve strength, rearrange or reorder the molecular or atomic structure, or to achieve other physical properties. In an embodiment, the heat treating process306can be done to improve machinability of the metal block160, for example, an annealing process that softens the metal block.

The metal block160may thereafter undergo a series of machining steps in which some metal is removed or cut away to product the finished parts. For example, to assist in subsequent machining, a groove forming process308can be conducted in which a plurality of guide grooves is cut into the metal block160. This may include the lengthwise groove180and the diagonal grooves182described above. Cutting the guide grooves can be accomplished by an end mill or similar cutting tool. The lengthwise grooves180and diagonal grooves182may penetrate the respective face of the metal block160only by a few centimeters, but can function as an outline or guide for subsequent cutting processes.

To bisect the metal block160into the first and second intermediate blanks174,176described above, a diagonal cut178can be made via a diagonal cutting process310in which a cutting tool like a band saw or blade saw is directed lengthwise through the metal block160. Alternatively, the diagonal cutting process310can be conducted using a laser or a plasma torch or electrical discharge machining. The diagonal cutting process310produces the first and second intermediate blanks174,176shaped as trapezoidal cuboids or prisms that have six opposing faces in which at least two opposing faces are non-parallel.

Another cutting process, in particular, a triangular cutting process312to produce the triangular cut188described above, can be conducted either before or after the first and second intermediate blanks174,176have been separated from the metal block160. The triangular cutting process312removes the triangular-shaped wedges190described above so that the resulting shape of the first and second intermediate blanks has the cross-section of a five-sided polygon. The triangular cutting process312can be accomplished with a plasma torch or a fuel-oxygen torch.

To produce the finished part from the first and second intermediate blanks174,176, further machining and, in particular, milling may be conducted to remove additional metal and produce the final shape. To produce the plurality of concavely arranged internal teeth194associated with the internal toothed segment150, a gear milling process314or gear hobbing process can be conducted. The gear milling process314can be conducted by penetrating the lengthwise face162of the first intermediate blank174with a mill or hob to remove metal and shape the vertically arranged individual teeth. Similarly, the gear milling process314can be conducted on the lengthwise face164of the second intermediate blank176with a mill or hob to shape the plurality of convexly arranged teeth196associated with the external toothed segment152. In an embodiment, either or both of the first and/or second intermediate blanks174,176can be used to produce either or both of the internal toothed segment150and/or external toothed segment152.

To reduce the weight of the internal and external toothed segments150,152while producing the structural supports200, a recessed milling process316can be conducted in which the plurality of pocket198are milled into the slanted faces184,186of the first and second intermediate blanks174,176. The recessed milling process316can be conducted using an end mill or similar cutting tool. Because the resulting structural supports200are generally oriented orthogonally with respect to the pluralities of concavely and convexly arranged teeth194,196, the structural support200may brace and support applied loads during meshing of swing gear assembly and the pinion that drives rotation of the swing assembly.

To facilitate installation of the internal toothed segment150and the external toothed segment152, a drilling process318an be conducted in which the plurality of axial through holes204are drilled with a drill bit into the recessed bearing surfaces202formed by the plurality of pockets198. Additional metalworking processes can be conducted to produce the finished parts corresponding to the internal toothed segment150and external toothed segment152such as, for example, further heat treatment such as direct hardening, induction hardening or carburizing to improve strength, wear resistance, etc.

A final step may be an assembly process320in which the internal toothed segments150and external toothed segments152are transported and delivered to an excavation site for assembly into the swing assembly130. A plurality of internal toothed segments150can be arranged and aligned to produce the circumference of the internal gear ring140that is concentrically located about the axis line132of machine rotation. Similarly, the plurality of external tooth segments152can be arranged to produce the circumference of the external gear ring142concentrically aligned about the axis line132of machine rotation. The internal and external toothed segments150,152, can be joined to adjacent segments by, for example, fasteners or welding. One of the assembled internal gear rings140or external gear rings142can be selected for assembly into the swing assembly of a dragline excavator or similar machine.

The disclosure therefore provides a swing gear assembly for large scale or heavy machinery which is assembled from a plurality of external and/or internal toothed segments. The external and internal toothed segments are manufactured via a series of metalworking processes intended to increase efficiency and reduce cost of manufacturing and to provide structural elements that may improve load-transfer ability and strength of the gear segments. These and other possible advantages and features of the disclosure are apparent to a person of skill in the art from the foregoing description and accompanying drawings.

The use of the terms “a” and “an” and “the” and “at least one” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term “at least one” followed by a list of one or more items (for example, “at least one of A and B”) is to be construed to mean one item selected from the listed items (A or B) or any combination of two or more of the listed items (A and B), unless otherwise indicated herein or clearly contradicted by context.