Note: Descriptions are shown in the official language in which they were submitted.
CA 02543769 1997-10-08
WING PANEL ASSEMBLY
This invention relates to assembly of airplane wing
panels, and more particularly to a method and apparatus for
assembling airplane wing panels with great accuracy and
efficient use of factory floor space.
BACKGROUND OF THE DISCLOSURE
Wing panels for commercial jet transport airplanes are
typically built up from long aluminum "planks" connected
together along longitudinal adjacent edges with splice
stringers and stiffened with parallel stringers extending
longitudinally of the wing. Empannage horizontal stabilizer
panels are also stiffened with stringers. The stringers are
spaced approximately 6"-8" apart chord-wise over the entire
surface of the wing panel and are fastener to the wing planks
by rivets or other fasteners approximately every 1"-2" along
the length of the stringers. A typical commercial jet
transport of about 300 seat capacity will have about 300,000
rivets fastening the stringers and splice stringers to the
wing planks to make up each of the upper and lower wing
panels, so it is imperative for an efficient wing fabrication
facility to high speed accurate equipment for drilling and
fastener installation with a minimum of manually installed
fasteners and rework.
In the classical wing panel fabrication process, the wing
planks are fixtured in position and are temporarily fastened
together with stringers and tack fasteners on an apparatus
similar to that shown in U.S. Patent No. 4,894,903 to Woods. Tack
fasteners are placed about every 20" to hold the wing panel
planks together securely enough to move them to a riveting
machine where the tacked-together wing panel is laid on
horizontal headers which support it at the desired compound
curvature for drilling and rivet installation to permanently
fasten the stringers to the wing planks. Afterward, the
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temporary tack fasteners are removed and replaced with
permanent fasteners.
This classical process is very wasteful of factory floor
space since the wing panel is supported in a stationary
horizontal position during riveting. It also requires large
and expensive equipment to perform the riveting, since the
drilling and riveting machine must be capable of precise
movements in five axes over the entire length and width of the
wing. The panel fixturing and temporary fastening are
typically performed on a panel jig having hard tooling to
locate the stringers and planks. Panel jigs are expensive
tools and are each dedicated to only a single airplane model.
The operations on the panel jig are performed in the vertical
orientation, but the assembled wing panel must then be "flown"
to the wing riveting machine and accurately indexed thereon,
which requires large and expensive crane equipment and takes
an entire shift to accomplish the transfer, during which both
the fixturing jig and the wing riveter are out of production.
During indexing of the assembled wing panel on the headers of
the wing riveter, the expensive wing riveter is sitting idle.
Thus, the existing is labor intensive, slow, and requires an
inefficient use of expensive factory floor space and
equipment.
Several attempts have been made in the past to provide
apparatus that is capable of riveting stringers to wing panels
in a vertical orientation. U.S. Patent No. 4,864,702 to Speller,
Sr. et al. and U.S. Patent No. 5,033,174 to Zieve disclose
apparatus for holding the.wing panel in a stationary vertical
position while a gantry or yoke moves along the wing and moves
tools vertically or chord-wise to perform operations on the
wing panel. These devices accomplish the.desirable saving of
factory floor space but require a complicated and expensive
mechanism for vertically moving the tooling to position it at
the desired rivet installation height chord-wise of the wing
panel. The modern requirements for extreme positioning
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precision of the stringers and ability to record statistical
data regarding hole parameters increases the cost involved in
adding the vertical movement capability into the moving gantry
or yoke.
SUMMARY OF THE INVENTION
Accordingly, it is an object of this invention to provide
a method and apparatus for fixturing wing planks and fastening
stringers to the wing planks using a wing fixture that is
vertically adjustable, thereby making possible the use of a
relatively simple and inexpensive machine tool for drilling,
hole conditioning and fastener installation having only
limited or no vertical travel capability. Another object of
this invention is to provide a method and apparatus for
fixturing wing planks and fastening stringers to the wing
planks wherein the stringers being fastened to the wing plank
assembly are always at a conveniently accessible height for
the workers to position additional stringers and to service
the hole drilling and fastener installation tooling. Still
another object of this invention is to provide an apparatus on
which other panels with different contour can be fabricated
with a quick and effortless changeover for improved cell
efficiency.
These and other objects of the invention are attained in a
method and apparatus for fabricating wing panels for airplane
wings at a desired curvature. The wing panels are made up of a
plurality of elongated wing planks attached together with
splice stringers along adjacent longitudinal edges and
stiffened with stiffening stringers parallel to each other and
to the splice stringers. A fixture for holding the planks in
the proper position relative to each other and at the desired
curvature is supported in an elongated pit. The fixture has a
number of headers, one each spaced lengthwise along the length
of the pit at about the spacing of wing ribs in the wing when
it is finally assembled. An elevator supports the fixture in
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the pit for precise adjustment of the fixture and the assembled
wing planks in a generally vertical direction. A stringer
positioning device is mounted alongside one longitudinal edge
of the pit for positioning a stringer loaded thereon against
the assembled wing planks accurately in accordance with the
wing design. A downwardly opening yoke having two arms
depending from a top member is suspended over the pit on a
support structure, such as a gantry spanning the pit, or a
traveling support tower on one side of the pit. The support
structure is supported for longitudinal motion lengthwise of
the pit on a saddle mechanism for moving the support structure
longitudinally of said pit, thereby to position the yoke and
the tools mounted thereon sequentially at fastener positions
spaced along the stringer. Each header may be released
individually frofn the panel and retracted away from the panel
and into the pit to allow the fastening yoke to access the
fastener locations covered by that header. Tools mounted on
opposite arms of the yoke performing clamp-up, drilling and
fastener installation functions to fasten the stringer to the
assembled wing panel planks on the fixture.
Description of the Drawings
The invention and its many attendant objects and advantages
will become more clear upon reading the following description of
the preferred embodiments in conjunction with the following
drawings, wherein:
Fig. 1 is a sectional elevation of a first embodiment of
an apparatus for practicing the method of this invention,
showing a representative wing panel supported on one of a
multitude of headers of a fixture, and being operated upon by
drilling and fastener installation tooling supported on the
depending arms of a yoke which is supported from one side of a
the pit in which the fixture is mounted for generally vertical
motion;
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Fig. 2 is a sectional elevation of a second embodiment of
an apparatus for practicing the method of this invention;
Fig. 3 is an end elevation of a third embodiment of an
apparatus for practicing the method of this invention;
Fig. 4 is a perspective view of the yoke assembly embodiment
shown in Fig. 2, but with two yoke assemblies over a wing panel
pit long enough to accept two wing panels supported end-to-end;
Fig. 5 is a schematic diagram of a control architecture
for controlling the elevators and the fixture, the saddle
mechanism for moving the yoke longitudinally along the pit,
and the tools on the yoke; and
Fig. 6 is an end elevation of a fourth embodiment of an
apparatus for practicing the method of this invention.
DESCRIPTION OF THE PREFERRED E1rIDODIMENTS
Turning now to the drawings, wherein like reference
numerals designate identical or corresponding elements, and
more particularly to Fig. 1 thereof, a yoke assembly is shown
having a 30 and associated supporting and motive structures
for suspending the yoke 30 over an elongated pit 32 containing
an elevator 33 for supporting a fixture 34 on which elements
of a wing panel are held for drilling, hole conditioning and
fastener insertion. The yoke 30 has a top cross member 36 and
two depending arms 38 and 40, at the bottom ends of which are
mounted opposed sets of tools 42 and 44 for hole drilling and
fastener installation.
The yoke assembly includes a support structure 46 to which
the yoke 30 is attached by way of a pivot pin 48 extending
through a pair of parallel knuckles at the lower end of the
arm 40. The pivot pin 48 enables the yoke 30 to pivot about an
"A" axis parallel to an "X" axis in the longitudinal direction
of the pit 32. Pivoting of the yoke 30 about the "A" axis
makes it possible to easily and accurately normalize the tools
42 and 44 to the curved surface of the planks of the wing panel
P at the point of drilling and fastener installation.
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The support structure 46 is mounted for rotation about a
vertical axis "B" on a saddle mechanism 52. Airplane wing
panels are curved in the span-wise direction as well as the
chord-wise direction, and rotation of the support structure 46
about the "B" axis enables the yoke 30 to rotate to a vertical
plane that is normal to the wing panel at the point of fastener
installation. Rotation of the support structure 46 on the
saddle mechanism 52 is effected by a bevel gear on the support
structure 46, driven by a servo motor and engaged with a ring
gear 55 on the saddle mechanism 52. Operating the servomotor
in one direction or the other drives the bevel gear and rotates
the support structure 46 about the ring gear 55 on the saddle
mechanism in one direction or the other to rotate the support
structure 46 to the desired vertical plane normal to the wing
panel at the desired point of fastener installation. Thus,
rotation of the yoke 30 about the "A" axis through the pivot
pin 48 and rotation about the "B" axis enables the yoke to be
positioned so that the tools 42 and 44 are normal to the plane
of the wing panel at any desired point of fastener
installation.
Linear motion of the support structure 46 in the "Z"
direction, that is, horizontally and perpendicular to the "X"
direction, is provided by a linear slide 53 by which the support
structure 46 is mounted on the saddle 52. Motion in the "Z"
direction enables the yoke to be translated horizontally in the
direction transverse of the wing panel to account for both
spanwise and chordwise curvature of the wing panel.
The saddle mechanism 52 on which the support structure 46
is mounted is in turn mounted for linear motion in the "X"
direction on tracks 54 extending alongside one longitudinal
edge of the pit 32. A conventional drive mechanism 56 drives
the saddle mechanism 52 along the tracks 54 to position the
yoke 30 at any desired position lengthwise of the wing panel,
and a scale is attached to the edge of the track for reading
by a pickup on the saddle 52 for positional feedback to a
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control system, described below. Examples of such drive
mechanisms abound in the machine tool art and include gear
drives along the edge of the track as in U.S. Patent No. 5,565,242
entitled "Lubrication Applicator" by Buttrick et al.and in U.S.
Patent No. 5,477,595 entitled "Stringer/ Clip Placement and
Drilling" by Peter McCowin. Other such conventional drive mechanisms
could also be used to drive the saddle mechanism 52 along the track
The tilt angle of the yoke 30 about the "A" axis, coincident
with the axis of the pivot pin 48, is controlled by a tilt angle
control mechanism 60, including a ball screw in a sleeve 62
driven by a servo motor 64. This adjustment makes possible the
tilting of the yoke 30 in its vertical plane to normalize the
line of action of the tools on the two arms 38 and 40 of the yoke
30 with the curve of the wing panel at the height of fastener
installation. A jack 66 between the support structure 46 and the
yoke arm 40 provides the capability for adjustment of the yoke in
the direction of the "Y" axis on linear bearings 67 to provide
compensation for vertical displacement caused by rotation of the
yoke 30 around the "A" axis and to provide compensation for
possible vertical inaccuracies in the "X" axis tracks 54.
The fixture 34 includes a series of headers 70 spaced about
two feet apart longitudinally of the pit. Each header 70 has a
curved edge corresponding to the desired outer mold line of the
wing panel P at the position of the header on the fixture 34.
The headers have attachment devices for releasably holding the
wing panel planks against the headers. The attachment devices
include suction cups mounted in a channel between two spaced
plates of the header which pull the panel against solid reference
surfaces of the header. -
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The vertical position of the headers 70 and the wing panel
mounted thereon is controlled by the elevator 33 mounted in the
pit 32. The elevator 33 includes a series of carriers 72 on
which the fixture 34 is mounted. The carriers 72 each have a
series of linear bearings 74 mounted along opposite edges thereof
for connection to guide rails 76 mounted at a steep angle in the
pit 32. A driver, such as a servomotor driven ball screw 80, is
mounted in the pit and is driven by a servomotor 82 for raising
and lowering the carrier 72 by engagement with a ball nut 84
attached to the carrier 72.
The headers 70 may be individually mounted on the carriers
72, one header 70 for each carrier. In this arrangement, the
guide rails 76 would be set at an angle selected to provide
movement of the headers 70 in a direction having a vertical
component and a horizontal component so as to move downwardly
into said pit and horizontally away from the wing panel when the
elevator driver operates the elevator to move the header 70 down
and away from the wing panel to clear the yoke 30 for movement
past the header 70. The angle is slightly greater than the
vertical angle 0 of the tangent to the wing panel P at its
maximum deviation from vertical.
In another form, the carriers 72 would carry a frame on
which the headers 70 would be mounted individually by swing arms
that would allow the headers 70 to swing away from the panel and
down into the pit to clear the way for the yoke 30 to move into
and through the space otherwise occupied by that header 70.
To provide the capability to fixture wing panels of other
configurations, additional headers 70 may be interleaved among
the headers 70 in current use. These other headers would remain
in the retracted position in the pit until required to fixture
another panel shape. Up to six sets of headers 70 for different
wing panel configurations could be accommodated. Additional
flexibility, as might be required to change over to a new model
product, may be accomplished by removing a set of headers 70 from
the fixture and replacing them with new headers.
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A stringer positioning device 88 is mounted alongside one
longitudinal edge of the pit 32 for positioning a stringer S
loaded thereon against the assembled wing planks on the fixture
34 accurately in accordance with the wing design. The stringer
positioning device 88 includes a series of stands 90 arranged in
a row alongside the pit 32 and a gripper device 92 mounted on the
ends of extension arms 94 at the ends of linear actuators 96
connected to the stands 90. The stringer S is clamped to the
gripper device 92 by swivels which enable the stringer to be
tilted slightly to lie flat against the wing panel P regardless
of the chordwise position of the stringer S on the panel P, since
the tangent of the curve described by the wing panel in the
chordwise direction will be different at different positions
around the chord of the wing panel P.
After the stringer S is loaded into the grippers by the
machine vigil attendant MVA, the actuators 96 are energized to
push the stringer S towards the panel P to achieve a firm contact
of the contact surface of the stringer S along the length of the
stringer S.
The tools 42 and 44 on the ends of the yoke arms 38 and 40
can include existing tools and processes used on conventional
fastener installation equipment. Operations contemplated for
this wing panel assembly cell include clamp-up of the stringer
and the wing panel plank at the fastener location, hole drilling
and hole preparation such as coldworking, reaming, countersinking
and hole inspection. Installation of fasteners such as rivets,
bolts, and/or lock bolts can be done with automatic fastener
insertion tools. The inserted fasteners, in the case of rivets,
can be secured by a hydraulic rivet squeezer or electromagnetic
rivet impact apparatus, and in the case bolts and lockbolts, with
nut or collar installation apparatus. One device that could be
adapted for use with this invention is the "Drill/Rivet Device"
shown in U.S. Patent No. 5,231,747. An advanced tooling system that
could be adapted for use with this invention is shown in U.S.
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Patent No. 6,240,332 by Buttrick et al entitled "Tooling Head
Controller".
Because this invention is intended to be used for wing panel
assembly on up to six different wing panel designs, and even more
different designs with exchange of sets of headers 70, a quick
release mechanism 98 is provided on the yoke arms 38 and 40 to
enable the tooling sets 42 and 44 to be quickly removed and
replaced with different sets of fastening tools. This simplifies
the tool design since one tooling set is not needed to perform
the fastener installation for all types of fasteners. The quick
release mechanism 98 also reduces down time of the machine for
maintenance and repair by the use of duplicate tooling which can
be used while the first set of tooling is being serviced.
In operation, the factory receives an order for one or more
wing panels of a certain design. As shown in Fig. 5, the design
of that wing panel is downloaded via a network 99 from a digital
database of an engineering authority for the product to a server
101 and thence to a machine tool controller 100 for controlling
the operations of apparatus and the tools. It is contemplated
that this invention will use the concepts of determinant assembly
taught in U.S. Patent No. 5,560,102 by Micale and Strand entitled
"Panel and Fuselage Assembly",
The wing panel planks are indexed onto the headers 70
using accurately dralled locating holes and index pins on the
headers. After the planks are loaded onto the headers 70, the
controller 100 executes a probe routine that directs the machine
to move a probe held by the tooling 42 to probe for coordination
features such as coordination holes, tool balls mounted in
coordination holes or accurately machined notches or the like
along edges of the wing planks. The probing routine locates the
actual position of the wing panel planks on the headers 70 with a
high degree of accuracy. The part program for the wing panel
product is normalized with the actual position of the wing panel
CA 02543769 1997-10-08
planks of the headers so that the part program now coincides
exactly with the actual position of the planks on the headers 70.
The controller 100 now energizes the elevator servomotors 82
to move the fixture 34 to the correct elevation for attachment of
the first stringer S and cues the attendant MVA to load the first
stringer onto the stringer positioning device 88. Normally, the
attendant will have already loaded a stringer onto the stringer
positioning device 88, so he now energizes the actuators 96 to
push the stringer S into position against the panel P. When the
stringer is in position, the controller 100 executes another
probe routine to locate the actual position of the stringer S
against the panel P, and normalizes the part program with the
actual position coordinates.
The controller 100 energizes the drive mechanism 56 to drive
the saddle 52 to position the yoke 30 at the location of the
first fastener. The servomotor 64 tilts the yoke 30 to normalize
the line of action of the tools 42 and 44 to the tangent of the
panel curve at the point of fastener installation. The elevation
of the panel by the elevator 33 accounted for the change in
elevation of the tools when the yoke tilted to the correct angle,
so no correction is needed. However, any correction in elevation
of the tools that may be needed for any reason can be
accomplished by operating the jack 55 to raise or lower the
support structure 46 by the desired increment. The hardware and
software are now configured to commence fastening the stringer S
to the panel.
The fastening routine in the machine controller 100 is now
executed to cause the tools to clamp up the stringer against the
panel plank, drill the fastener hole, condition the hole, insert
the fastener and secure the fastener. The tooling then unclamps
and the controller directs the drive mechanism 56 to drive the
saddle 52 to position the yoke 30 at the location of the next
fastener where the fastener installation operations are repeated.
No adjustment will normally be required in the vertical direction
since the stringer is positioned parallel to the track 54
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(normally horizontally) so the tools 42 and 44 remain opposed at
the stringer level throughout the entire range of travel of the
yoke 30 from one end of the panel P to the other end.
When the fastener installation has proceeded to the point
that the yoke 30 draws close to a header 70, the controller 100
operates a valve in the vacuum line to the suction cups on the
header to release the header 70 from the panel, and the elevator
70 is withdrawn from the panel P and retracted into the pit to
give access to the fastener positions covered by the header and
to clear the space for the tooling to pass the position of the
header 70. The remaining headers 70 still connected to the panel
P are more than adequate to hold it rigidly in position for the
fastening operations in the vicinity of the retracted header 70.
The mass of the yoke 30 and the attached tooling 42 and 44
will normally tend to cause a certain amount of oscillation when
the drive mechanism 56 starts and stops the saddle 52 to position
the yoke at each hole location in order. Fastener installation
operations must normally wait until the oscillations have damped
to a certain maximum amplitude which can affect cycle time, that
is, the average time to complete the installation of a single
fastener and move to the next position. Because cycle time is an
important factor in assessing machine efficiency, oscillations of
this nature are considered undesirable and to be minimized.
Accordingly, when moving the machine from one fastener location
to the next, the controller 100 is programmed to swing the
support structure and yoke 30 about the "B" axis in the direction
of movement of the saddle 52 along the track 54, and then swing
it back again as the saddle 52 reaches its designated position
for the next fastener location. This routine reduces the
oscillation amplitude to the extent that fastener installation
operations can commence immediately and cycle time is
significantly improved.
Turning now to Fig. 2, a second embodiment of the invention
is shown having a yoke 110 suspended on a yoke mount 108 from a
support structure 112 by a pivot 114 which allows the yoke to
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rotate about a horizontal "A" axis, coincident with the axis of
the pivot 114. The.support structure 112 is mounted on a saddle
116 by way of a linear slide mechanism 118 that allows the
support structure to move laterally toward and away from an
elongated pit 120, like the pit 32 in the first embodiment. The
saddle 116 is mounted on a track 122 that extends along one
longitudinal edge of the pit 120 in the "X" direction, parallel
to the "A" axis. A driver 124 is provided for driving the saddle
116 along the track 122, as in the embodiment of Fig. 1.
A tilt control mechanism 126 is attached between the support
structure 112 and the yoke mount 108 for tilting the yoke 110 to
a desired angle about the "A" axis. The tilt control mechanism
126 shown has a ball screw 128 driven by a servomotor 130
pivotally attached to the support structure 112. The ball screw
is engaged with a ball nut 132 pivotally attached to an arm 134
extending from the yoke mount 108. Operation of the servomotor
13 in one direction or the other extends or retracts the ball
screw 128 in the ball nut 132 and rocks the arm 134 and the
attached yoke mount 108 about the pivot 114 to rotate the yoke a
controlled angular displacement about the "A" axis.
The yoke mount 108 includes a rotational joint 136 providing
controlled rotation of the yoke 110 about a vertical "B" axis.
The rotational joint 136 includes a ring gear 138 and a pinion
gear driven by a servomotor 140. An optical scale can be
attached to the ring gear for positional feedback to confirm the
normal feedback from the servomotor to provide independent data
to the controller 100 regarding the angular position of the yoke
110 about the "B" axis.
The pit 120 contains an elevator (not shown) for providing
elevation control of a fixture 142, shown schematically as a
header 70 in broken lines in the retracted position, and shown in
solid lines in two working positions at the upper and lower
extremes of the working positions. The pit and non-illustrated
elevator are shown schematically because they are identical to
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the pit 32 and elevator 33 shown and described for the embodiment
of Fig. 1.
A stringer positioning device 144 is mounted along the
opposite longitudinal edge of the pit 120 from the track 122. It
includes a series of stanchions 146 arranged in a straight line
and a bar 148 pivotally mounted on each stanchion 146. The bars
148 are provided with two detents that selectively index the bars
148 at either of two horizontal positions, 180 apart. A
stringer gripper 150 is mounted on the end of an extension arm
152, in turn attached to a linear actuator 154 mounted in each
end of the bars 148. The double ended stringer positioning
device 144 enables the attendant MVA to load a stringer S onto
the grippers 150 at one end of the bars 148 while a stringer is
held against the panel P by the grippers 150 at the other end of
the bars 148 during fastener installation operations by the
machine.
Operation of the machine shown in Fig. 2 is the same as the
operation of the embodiment of Fig. 1, with the exception that
tilting the yoke 110 about the "A" axis and rotation of the yoke
110 about the "B" axis does not result in significant
displacement of the line of action of the tools 42 and 44.
Operation to minimize oscillation of the yoke during movement of
the machine along the "X" axis between fastener locations
involves over-travel beyond the new fastener location and then a
slight backward movement in the "X" direction to nullify the
momentum imparted into the yoke during initial movement toward
the new fastener location.
As shown in Fig. 3, a third embodiment of the invention
includes a support structure in the form of a gantry apparatus
160 having a top cross member 162 supported on two upright
supports 164, each support carried by a saddle 166 mounted on
rails 168 for linear motion in an "X" direction longitudinally of
an elongated pit 32 spanned by the gantry 160. A carrier 172 is
mounted on the top cross member 162 on two parallel rails 174
mounted thereon and supports a yoke orienting system including a
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yoke mount 176 like the yoke mount 108 in Fig. 2. A driver 178
is attached to the carrier 172 for driving the carrier 172 along
the rails 174 laterally of the pit 32. The driver 178 includes a
servomotor operated by the controller 100 for driving a pinion
gear engaged with a gear rack on one of the rails 174 to move the
carrier 172 in the "Z" direction to a selected position on the
cross member 162 over the pit 32.
A yoke 180 is hung from the yoke mount 176 for orienting the
yoke 180 to positions that will orient the line of action of the
tools 42 and 44 normal to the curvature of the panel P at any
designated fastener location. The yoke mount 176 has the
capability of rotation about a vertical "B" axis and for tilting
about a horizontal "A" axis parallel to the "X" axis. Controlled
rotation about the "B" axis under control of the controller 100
is effected by a servomotor 182 driving a pinion gear engaged
with a ring gear 184 on the mount 176 as in the embodiment of
Fig. 2. Tilting of the yoke mount 176 and the yoke 180 is
effected by a tilt control mechanism 184 whose structure and
operation is the same as the tilt control mechanism 126 of the
embodiment shown in Fig. 2, so the description of that mechanism
will not be repeated here.
A stringer positioning mechanism 190 for positioning
stringers at desired positions against the wing panel P includes
a series of upright stanchions 192 mounted on a straight row
alongside one longitudinal edge of the elongated pit 170, and a
series of bars 194 pivotally supported at the tops of the
stanchions 192. The bars 194 have stringer grippers 196 at the
ends of extension bars 198 mounted at the extreme ends of the
bars 194 for securely gripping a stringer S and orienting it
accurately at the designated position against the panel P. A
linear actuator in the bars 194 can be energized to press the
stringer mounted in the grippers against the panel, holding it
firmly against the panel P.
The planks that make up the panel P are loaded onto headers
70 of a fixture supported on an elevator 33, as in the embodiment
CA 02543769 1997-10-08
shown in Fig. 1. The panel planks are oriented on the headers 70
such that the locations at which the stringers are to be attached
are horizontal. The stringer positioning mechanism 190 holds the
stringer horizontally at a precisely known elevation, and the
elevator 33 lifts the headers 70 under control of the controller
100 to position the panel planks for the panel P at the correct
elevation relative to the stringer positioning mechanism 190 so
that the stringer is placed exactly where it belongs on the panel
P in accordance with the design of the wing panel that was
downloaded via the network 99 from the engineering digital
database and converted into a part program for the controller 100
for controlling the operations of elevator 33, the drivers on the
support structure and yoke orienting system, and the tools 42 and
44.
The stringer positioning mechanism 190 has a stringer
gripper 196 at each end so that a stringer can be loaded onto the
gripper at one end while the stringer positioning mechanism 190
is holding a stringer at the other end while the tools 42 and 44
are attaching it to the panel P. The bars 194 are provided with
detents at their connection to the stanchions 192 to index the
bars selectively at an exactly horizontal orientation at either
of two positions 180 apart.
The operation of the embodiment shown in Fig. 3 is the same
as the operation described for the embodiment of Fig. 1, so it
will not be repeated here.
A tandem arrangement of the invention is shown in Fig. 4
using the type of support structure shown in Fig. 2. Two
separate elongated pits 120 and 120' are shown, although a single
pit of the equivalent length could be used. Two support
structures 112 and 112' are mounted on saddles 116 and 116' on an
elongated rail 122' for linear movement longitudinally of the
pits 120 and 120'. Yokes 110 and 110' are supported on the
support structures 112 and 112' in the same manner as described
for the embodiment of Fig. 2. The operation of each support
structure and yoke is the same as that described for Fig. 2.
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The tandem arrangement shown in Fig. 4 provides a
production capacity that is more than twice the capacity of a
single yoke apparatus because the panel P mounted on the set
of headers 70 can be operated upon by two yokes 110 and 110'
while planks are loaded onto the headers 70' or while the
fixture or elevator in either pit is being serviced or
changed, thereby eliminating idle time for either yoke system.
Turning now to Fig. 6, a yoke 200 includes two legs 202
and 204 depending from an upper cross member 206. Each arm
202 and 204 has a set of tools 208 and 210 attached by a
connector mechanism, that may provide quick change capability
for easy detachment and replacement for tool maintenance and
change of tools for different wing designs and sizes. The
tool sets 208 and 210 operate on the wing panel at a tool
point 212 approximately midway between them..
The yoke arm 204 has a curved abutment 215 on its outer
surface 217 that has a cylindrical convex curve with a radius
of curvature equal to the distance R from the surface 217 to
the tool point 212. The yoke is supported on a support member
220 having a cylindrical concave surface 222 also having the
same radius of curvature R. A pair of curved tracks (not
shown) is mounted on the concave surface 222 of the support
member 220, and a pair of linear bearings (not shown) is
mounted on the convex curved surface 217 of the yoke arm
abutment 215, engaged with the tracks on the surface 222.
Curved track linear bearings of this type are known
generically as "goniometric bearings" and are commercially
available, for example, from THK designated as R Guide Type
HCR.
Since the yoke 200 swivels about the tool point 212,
there is no change in the vertical position of the tool point
when the yoke tilts, as there is in the embodiments of Figs.
1,2 and 3 when the yoke tilts. Therefore, there is no need to
provide vertical adjustment capability to accomodate a change
in the vertical position of the tool point as the yoke tilts.
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CA 02543769 1997-10-08
However, if a small vertical adjustment capability is desired,
it can be provided with a small jack in the support member 220
or the elevator mechanism 33 can be provided with a fine
adjustment for micro-adjustament of the vertical position of
the wing panel on the fixture 34 in the pit 32.
Adjustment of the tilt angle of the yoke 200 is effected
by an adjustment mechanism including a ball screw 225 driven
by a servomotor 228 pivotally connected to the support
structure 220 at a pivot 229. A ball nut 230 is engaged with
the ball screw 225 and is pivotally connected to an arm 232
attached to the curved abutment 215. Operation of the
servomotor 228 in either direction causes the ball nut 230 to
translate linearly along the ball screw 225 and the arm 232 to
tilt and rotate the curved abutment 215 on the curved tracks
The yoke 200 and the support member 220 are supported
alongside the pit 32 in the same manner as the embodiments of
Figs. 1 and 2, and their operation is the same as those
embodiments except that there is no need to adjust the
vertical position of the tool point 212 when the tilt angle of
the yoke is changed to accomodate the curvature of the wing
pane. Therefore, there is not need to repeat the description
of their structure and operation.
The wing panel assembly method and apparatus described
above can be used advantageously to fasten stiffening
stringers to wing planks that are to be assembled as full wing
panels on another larger machine. This efficiently makes use
of a small machine to do most of the work and makes possible
the purchase of fewer large (and expensive) machines to do the
splice stringer fastening which requires a greater span in the
case of large airplane wing panels.
Obviously, numerous modifications and variations of the
preferred embodiments described above are possible and will
occur to those skilled in the art in light of this
specification. Accordingly, it is expressly to be understood
that these variations and modification, and the equivalents
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thereof, are to be considered within the spirit and scope of
this invention, as defined in the following claims, wherein I
claim:
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