Metal working – Method of mechanical manufacture – Assembling or joining
Reexamination Certificate
1998-10-29
2001-11-20
Hughes, S. Thomas (Department: 3726)
Metal working
Method of mechanical manufacture
Assembling or joining
C029S897300
Reexamination Certificate
active
06317957
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to large earth excavators, and more particularly to a method of fabricating the base of an excavator at the site at which the excavator is to be used.
Certain excavators have large circular bases that support a rotating mechanism for an upper works and the drive mechanisms for rotating the upper works. Such bases have been built in diameters up to 105 feet. Such bases can have internal diaphragms located in a circumferential, radial, rectangular, or triangular pattern, or combinations thereof. Excavator bases have been constructed in factories. Because of their size, the bases must be built in segments or sections. Sometimes these segments or sections are assembled in the factory to check for fit, disassembled, and then the segments or sections are shipped piece by piece to the job site at which the base will be assembled. The base segments or sections are then reassembled and welded together, machined as required, and then assembled to the excavator.
FIGS. 1
,
2
, and
3
of the drawings illustrate one example of an excavator base designed for fabrication in a factory. This excavator base is characterized by being formed from a series of outer segments A (FIG.
1
), inner segments B (FIGS.
1
and
3
), central segments C (FIG.
1
), and a base center D (FIG.
1
). Each of the elements A, B, C and D are separately built and assembled together in the factory. The elements are subsequently disassembled and placed on flat bed trailers or railroad cars for transportation to the site. The size of such trailers or railroad cars dictate the maximum size of the individual elements. The maximum size of the individual elements also dictates the design of the interior diaphragms. When segments are used as in
FIGS. 1-3
, radial diaphragms and tangential diaphragms of many sizes and shapes are dictated.
This invention provides a method for the on-site fabrication of an excavator base allowing for optimization of design without concern for shipping constraints of large sections.
SUMMARY OF THE INVENTION
According to the invention, an excavator base is fabricated by first erecting a substructure. Large flat plates are then laid upon the substructure and are welded together at their edges. The welded plates are then cut to define a perimeter of a floor plate. Vertical interior diaphragms and edge plates are mounted on the floor plate in various patterns and welded to the floor plate and to each other. A second series of large plates are assembled and welded together at their edges to form a top plate which is welded to the interior diaphragms and edge plates. The top plate is also cut to define the outer perimeter. The completed base can be removed from the substructure.
Preferably, the base includes a base center that is prefabricated and stress relieved. The base center is mounted on and welded to the floor plate before the diaphragm and edge plates are assembled. The top plate may be assembled, welded, and cut in place on the assembled diaphragms and edge plates. Alternately, the top plate may be assembled, welded, and cut directly on the superstructure, and then removed and set aside for later attachment.
A system of brackets and wedges may be used to level adjacent flat plates for welding.
A building structure or a tent can be erected over the foundation. Modern welding, cutting, and inspection equipment can be used at the site.
The substructure may be mounted on upright structural shapes that are mounted in the foundation. The substructure can also be supported on upright jacks.
The method allows the use of the largest flat plates that can be shipped to the fabrication site. The method also allows for the use of repetitive sizes and shapes for the top plates, bottom plates, and interior diaphragms. Both factors contribute to reducing labor and material requirements in addition to the transportation costs that are saved compared to factory-built bases.
An excavator base fabricated using the method of the invention has flatness comparable to a base assembled from factory built sections or segments.
The foregoing and other objects and advantages of the invention will appear in the detailed description which follows. In the description, reference is made to the accompanying drawings which illustrate a preferred embodiment of the invention.
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patent: 3064770 (1962-11-01), Andrews
patent: 3073573 (1963-01-01), Haskins
patent: 3237295 (1966-03-01), Konzak
patent: 3239927 (1966-03-01), Hazak
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patent: 3956816 (1976-05-01), Short
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patent: 4121747 (1978-10-01), McFatter
patent: 4142284 (1979-03-01), Steuber
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Austin David S.
Gregor Robert A.
Bucyrus International, Inc.
Hughes S. Thomas
Nguyen T.
Quarles & Brady LLP
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