Note: Descriptions are shown in the official language in which they were submitted.
1037-7
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TECHNIC~L FIELD OF T~E INVENTION
The present invention relates to excavators such as
draglines and stripping shovels, and more particularly to
a rotatable frame of such excavators for accommodating
internally mounted swing drive units.
B~C~GROUND OF THE INVENTION
In most conventional types of heavy-duty excavating
machines of the dragline or stripping shovel type, there
is usually provided a rotatable frame having a top deck
and a bottom plate. A stationary ring gear is mounted to
a base of a crawler unit or to a tub which is supported
on the ground adjacent to or in a pit of a surface mine.
The rotating frame supports at least one drive unit,
having a pinion drivingly engageable with the ring gear
which operates to swing the rotatable frame.
Traditionally, such swing drive units have been mounted
on the top deck with the pinion shaft thereof extending
through vertical openings in the rotating frame. These
existing designs incorporate a long main rotating shzft
which connects the gear case mounted on the top deck of
the rotating frame to the main rotating pinion located
below the bottom plate of the rotating frame. The long
main rotating shaft is subject to torsional windup which
can cause unbalanced motor load sharing. Severe
vibrational problems can also occur in this condition.
The overhung main rotating pinion loads also cause the
main rotating shaft to deflect i~ bending sufficiently
that the pinion teeth must be heavily crowned to
compensate for this misalignment. Additionally, such
mounting arrangements have been found not to be entirely
satisfactory in that configurations require precise
machining of the rotating frame for mounting the swing
unit and assuring proper alignment of the pinion shaft
with the ring gear. ~
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Large walking dragline machines typically utilize
longitudinal bulkheads to support the machine's major
digging loads from the gantry front and back leg
structures, boom structure, hoist machinery and drag
machinery. Transverse bulkheads are utilized to support
the machine during the machine's propel operation. Both
the longitudinal and transverse bulkheads are blended
together at the roller circle bulkhead to support the
roller circle loads. Typically this bulkhead
configuration consists of an egg crate or waffle type of
construction, designed to resist deflection. Such
designs present a complex loading and stress pattern in
transferring the load from the machinery located on the
deck of a dragline to the dragline frame which results in
an indeterminate and complex structure for analysis and
manufacture.
The precise machining of the rotatable frame and
the alignment of the pinion shaft with the rin~ ge~r
involves a comparatively high manufacturing cost. It is
highly desirable to provide a swing drive unit for an
excavator which can be effectively and economically
installed in the machine in the field and properly
aligned with the ring gear of the machine to provide full
bearing contact between the teeth of the meshing gears
and which provides maximum efficiency in torque
transmission.
A need has thus arisen for a rotating frame
structure for a dragline which will permit the
accommodation of internally mounted swing drive units
while simultaneously providing a more simple and
efficient frame construction having an easily identified
and calculated load paths. A need has further arisen for
a rotating frame for mounting swing drive assemblies
which provides for uniformity of stiffness around a
roller circle and provides uniform distribution of loads
in the roller circle.
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S~MMARY OF T~E INVENTION
In accordance with the present invention, a frame
for an excavating machine having a ring gear and drive
units mounted within the frame for rotating the frame
relative to the ring gear is provided. The frame
includes top and bottom plates. A plurality of
compartments are circularly disposed within the frame and
between the plates for receiving the drive units. A
plurality of bulkheads are disposed within the frame and
between the plates and between the compartments thereby
providing uniformity of stiffness within the frame.
In accordance with another aspect of the present
invention, a frame for an excavating machine having a
ring gear wherein the frame is rotated with respect to
the ring gear is provided. The frame includes top and
bottom plates. A plurality of compartments are
circularly disposed within the frame and between the
plates. A plurality of drive units are provided wherein
each drive unit is mounted within one of the plurality of
compartments below the top plate. The drive units extend
below the bottom plate for driving engagement with the
ring gear. A plurality of radially disposed bulkheads
are located within the frame between the top and bottom
plates and between the plurality of compartments.
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BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the present
invention and for further advantages thereof, reference
is now made to the following Description of the Preferred
Embodiments taken in conjunction with the accompanying
Drawings in which:
FIGURE 1 is a side elevational view of an
excavating machine utilizing swing drive units installed
within compartments of the rotating frame of the present
invention;
FIGURE 2 is an enlarged cross sectional view taken
generally along sectional lines 2-2 of FIGURE 1.
FIGURE 3 is a top plan view of the rotating frame
of the present invention shown in FIGURE 1 with the top
deck removed;
FIGURE 4 is an enlarged cross sectional view taken
generally along sectional lines 4-4 of FIGURE 3; and
FIGURE 5 is a schematic top plan view of the
rotating frame of the present invention shown in FIGURE 1
illustrating load paths.
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DETAILED DESCRIPTION OF THE INVENTION
Referring simultaneously to FIGURES 1 and 2, a
dragline machine, generally identified by the numeral 10
is illustrated. Dragline machine 10 is illustrated for
stationary operation and is mounted in a tub 12, having a
top plate 12a and bottom plate 12b; however, it is
understood that the present invention can also be
utilized on a dragline machine which incorporates a
crawler unit. Dragline machine 10 includes a live roller
circle, generally identified by the numeral 16 which
supports a rotating frame assembly, in accordance with
the present invention, and is generally identified by the
numeral 20.
Connected to rotating frame assembly 20 is a boom
24 which is supported at its outer end or point by
pendants 26 secured to the upper end of a gantry 28.
Gantry 28 is mounted to rotating frame assembly 20, and
is partially enclosed by a housing 32. Also disposed
within housing 32 and supported on rotating frame
assembly 20 is hoist and drag machinery which operates
hoist lines 34 and drag lines 36. Hoist lines 34 are
wound on a hoist drum 40, extend upwardly, over a set of
sheaves 42 mounted on the front legs of gantry 28, extend
forwardly, over and around a set of boom point sheaves
and extend downwardly to where they are connected to a
drag line bucket (not shown). Drag lines 36 are wound on
a drag line drum 44, extend forwardly and over and around
a set of fairlead sheaves 46 and extend forwardly where
they are operatively connected to the front end of the
drag line bucket.
Dragline machine 10 includes a plurality of swing
drive units, generally identified by the numeral 50.
Swing drive unit 50 is utilized for causing rotation of
rotating frame assembly 20 through engagement with a
stationary ring gear 54 which is mounted to tub 12.
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Rotating frame assembly 20 includes a top deck 20a having
an aperture 56 and a bottom plate 20b.
Referring now to FIGURE 2, the present rotating
frame assembly 20, as previously stated, is supported on
live roller circle 16 at bottom plate 20b. Ring gear 54
is disposed concentrically with live roller circle 16 on
tub 12. Live roller circle 16 includes a lower circular
rail 58 mounted on tub 12, an upper circular rail 60
mounted on the underside of bottom plate 20b of rotating
frame assembly 20 and a plurality of rollers 62. Rollers
62 are supported on shafts 64 by a cage assembly 66.
Rollers 62 are supported on lo~er circular rail 58 and
upper circular rail 60 is supported on rollers 62 so that
rotating frame assembly 20 can be rotated or swung
relative to tub 12 about the vertical central line of
live roller circle 16.
Each of swing drive units 50 are mounted to
rotating frame assembly 20 through aperture 56 and
between top deck 20a and bottom plate 20b. Any suitable
number of swing drive units 50 can be utilized with a
dragline machine 10 determined by the machine size and
required swing torque. Swing drive unit 50 includes a
vertical electric motor 70 mounted on top of a planetary
gear case 72 through a grid coupling 74. Planetary gear
case 72 is mounted on a removable housing 78 which
contains a main rotating pinion 82 mounted on a rotating
shaft 84. Pinion 82 is disposed in driving engagement
with ring gear 54 and extends below bottom plate 20b of
rotating frame assembly 20.
Electric motor 70 is located on a support which is
integral with planetary gear czse 72 by a pilot register
(not shown). A disk brake 96 is mounted on the top of
motor 70. Motor 70 drives an input shaft (not shown) of
planetary gear case 72 through grid coupling 74. Pinion
shaft 84 is supported in housing 78 through antifriction
bearings 100. The output of planetary gear case 72
drives pinion shaft 84 by a spline connection 102.
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Pinion shaft 84 utilizes a top bearing cartridge assembly
106. Housing 78 is located on bottom plate 20b of
rotating frame assembly 20 by a pilot register 110.
Planetary gear case 72, housing 78 and bottom plate 20b
of rotating frame assembly 20 are interconnected by
tensioned fasteners 114. Actuation of motor 70 causes
driving engagement of pinion 82 with ring gear 54 to
cause rotating frame assembly 20 to rotate relative to
tub 12 in a conventional manner in order to swing
rotating frame assembly 20.
Because swing drive unit 50 is mounted between top
deck 20a and bottom plate 20b of rotating frame assembly
20, the length of pinion shaft ~4 can be significan.ly
decreased resulting in a compact swing drive unit 50
thereby minimizing torsional windup. Swing drive unit 50
being mounted to bottom plate 20b of rotating frame
assembly 20 through housing 78 and straddle bearings 100
significantly eliminates the bending deflection of pinion
shaft 84. Any misalignment between pinion 82 and ring
gear 54 becomes a function of the stiffness of bottom
plate 20b of rotating frame assembly 20. The modular
arrangement of swing drive unit 50 including planetary
gear case 72 and housing 78 provides for easy maintenance
in the field. For example, planetary gear case 72 can be
quickly replaced by a completely assembled spare
planetary gear case 72 which is more economical to stock
than previously existing entire larger parallel shaft
gear cases. With the use of planetary gear case 72, it
is possible to place more total swing horsepower on
rotating frame assembly 20. With the increased total
swing horsepower provided by swing drive unit 50, the
dragline machine 10 can be productive even when less than
all the swing drive units are in operation.
The use of planetary gear case 72 in swing drive
unit 50 allows drive units 50 to be smaller in size and
weight than prior such drive units. Because drive units
50 are smaller, and have a smaller combined footprin', a
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greater number of units can be utilized with dragline
machine 10 which results in several advantages achieved
by the present invention. One advantage is that the face
width of ring gear 54 can be decreased. Further, because
there are more meshing points at reduced loads between
pinion 82 and ring gear S4, the size of the teeth of ring
gear 54 can be made smaller.
Referring simultaneously to FIGURES 3 and 4,
wherein like numerals are utilized for like and
corresponding components previously identified with
respect to FIGURES 1 and 2, the present rotating frame
assembly 20 will now be described. FIGURES 3 and 4 are
illustrated with top deck 20a removed for clarity of
illustration. Rotating frame assembly 20 includes a
circular bulkhead 120 positioned over live roller circle
16 (FIGURE 1). Swing drive units 50 are
circumferentially disposed around circular bulkhead 120
and, may include, for example sixteen, for operation of
dragline machine 10. Thus, the swing drive loads acting
on rotating frame assembly 20 are balanced resulting in a
zero net reaction at the center journal due to swing
drive loads when rotating frame assembly is swinging.
An important aspect of the present invention is the
use of radially disposed bulkheads positioned between top
deck 20a and bottom plate 20b and located between swing
drive units 50. Bulkheads 130-156 are approximately
radially disposed with respect to circular bulkhead 120
and provide for uniformity of stiffness around live
roller circle 16. Bottom plate 20b of rotating frame
assembly 20 is of sufficient thickness for minimizing the
stress and deflection around swing drive units S0.
FIGURE 5 illustrates the bulkheads which define the
load paths associated with dragline machine 10. Path 160
defines the boom load path; path 162 defines the mast and
gantry load path; path 164 defines the fair lead and tri-
structure backleg load path; ani patn 166 defines the
propel load paths.
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It therefore can be seen that the present invention
provides for an improved rotating frame assembly for use
with internally mounted swing drive units for a dragline
machine in which the swing drive units are mounted
between the top deck and bottom plate of a rotating frame
assembly. In this manner, the swing drive assembly
including gear case and the motor is installed inside the
compartment of a rotating frame to clear the top deck.
The entire gear case assembly can be lifted up through an
opening in the top deck plate o~ the rotating frame
assembly thus minimizing down time for gear case repair
or replacement. The rotating frame assembly of the
present invention utilizes approximately radially placed
bulkheads between the swing drive assemblies for
uniformity of stiffness around the roller circle.
Whereas the present invention has been described
with respect to specific embodiments thereof, it will be
understood that various changes and modifications will be
suggested to one skilled in the art and it is intended to
encompass such changes and modifications as fall within
the scope of the appended claims.
