Radiant energy – Photocells; circuits and apparatus – With circuit for evaluating a web – strand – strip – or sheet
Reexamination Certificate
1998-11-24
2001-01-09
Allen, Stephone B. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
With circuit for evaluating a web, strand, strip, or sheet
C029S243500, C227S069000, C340S686500
Reexamination Certificate
active
06172374
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a homing sensor, and more particularly, to a laser detector for indicating alignment with an indexing device.
2. Background of the Invention
Traditional manufacturing techniques for assembling components to produce large mechanical structures to a specified contour have relied on fixtured tooling techniques utilizing assembly jigs and templates to locate the parts correctly relative to one another. Unfortunately, this method often yielded parts outside of acceptable tolerance because of imperfections in the templates or changes in the fixtured tooling caused by temperature variations.
To solve the problems encountered by traditional techniques, a system and method for assembling components was developed that utilized spatial relationships between key features of subassemblies as represented by coordination holes drilled into the subassemblies using numerical part definition records. The subassemblies were made intrinsically determinate of the dimensions and contour of the assembly.
The use of key features to determine the dimensions and contour of an airplane fuselage section is shown in FIG.
1
. Here, a skin
20
has a plurality of stringers
22
and a plurality of shear ties
24
riveted thereon. A frame member
30
having a curved contour which is the same as the desired contour of the airplane fuselage is then riveted to the shear ties
24
and stringer clips
26
.
The stringers
22
, the shear ties
24
and the stringer clips
26
must be fastened to the fuselage skin
20
with extreme accuracy and consistency. Accuracy of parts manufacture ensures that the airplane will come together perfectly with no pre-stressed parts and no cosmetic imperfections.
Initially, a computer numerically controlled (CNC) machine tool performs machining operations on the skin
20
. Coordination holes are drilled in the skin
20
and the stringers
22
. Corresponding coordination holes are also drilled in the shear ties
24
and the stringer clips
26
. A final machining operation of edge routing is performed by a high speed routing end-effector to route the edges of the fuselage skin
20
to the correct dimensions, as specified by the original part definition data base, by accurately locating the edges of the skin relative to the coordination holes in the skin.
The stringers
22
are tack fastened to the skin
20
through their aligned coordination holes. Then the shear ties
24
and stringers
22
are drilled and riveted to the skin
20
. The stringer clips
26
are inserted at the correct location and are held in place while drilled and riveted to form a panel
34
.
The skin
20
also has a series of panel-to-panel coordination holes
32
drilled along the edge of the skin
20
. The panel-to-panel coordination holes
32
are used to position the panels
34
relative to each other. The panels
34
are still relatively flexible so the ultimate configuration is determined by the parts and their matched coordination holes.
The panel-to-panel coordination holes
32
are aligned on adjacent holes and sealant is applied between the facing surfaces of the panel edges. The panels
34
are aligned so that the panel-to-panel coordination holes
32
on adjacent panels
34
line up exactly and the two panels are fastened together at their adjacent edges by temporary cleco fasteners through the coordination holes. The panels are then drilled and riveted to permanently fasten them together to form a super panel
36
.
Coordination holes are drilled into the frames
30
and are aligned with the coordination holes in the stringer clips
26
. The frames
30
are fastened and their alignment determines the contour of the super panel
36
. Thus, the contour is independent of any hard tooling. Once the super panel
36
is formed, the temporary cleco fasteners holding the parts in position are replaced by permanent fasteners.
The super panels
36
are temporarily fastened using the panel-to-panel coordination holes
32
to form fuselage quarter panels which are in turn temporarily fastened to form a lower fuselage lobe
38
A and an upper fuselage lobe
38
B, as shown in
FIGS. 2A and 2B
. A floor grid
40
is aligned with the lower lobe
38
A using coordination holes, and is fastened in place. The fixture
44
does not determine the contour or dimensions of the fuselage. Instead, the coordination holes drilled into the floor grid
40
determines the cross-dimensions of the fuselage
42
.
Once the frame members
30
and lobe skin coordination holes
46
are all aligned and temporarily fastened with cleco fasteners, they are drilled to form the final fuselage section
42
, as shown in FIG.
2
B. The fuselage section
42
is then disassembled, de-burred, cleaned, and sealant is added.
After sealing, each super panel
36
is again aligned using the coordination holes. The overlapping portion of the panels
36
, a lap joint
48
, is shown in
FIGS. 2B and 2C
. Each lap joint
48
has a plurality of columns
50
, where each of the columns
50
has
3
rows of rivets
52
A-C. Two rivets of the rows
52
A and
52
C are for rivets that require a countersink as well as drilling.
The super panels
36
could be fastened to form a quarter panel by an assembly device, such as that described in U.S. Pat. No. 4,662,556 (the '556 patent). However, the device described in the '556 patent moves a working unit along a guide beam that is supported by two huge arc-shaped girders, and could not be used to form the lower or upper fuselage lobes
38
A and
38
B, respectively, because of its size and design. Simply put, the unit described in the '556 patent or any variations thereof would not fit within the fuselage lobes
35
A and
38
B, and certainly not the fuselage assembly
42
. Attempts to redesign the assembly device discussed in the '556 patent to handle larger portions of the fuselage assembly
42
have failed because of severe problems with vibration which interfered with the proper seating of fasteners such as rivets. Further, the assembly device discussed in the '556 patent is not versatile and requires an expensive and heavy support structure.
Presently, the fuselage quarter panels
36
and, lower and upper lobes
38
A and
38
B, and the final fuselage assembly
42
are re-tacked into position after being filed, cleaned, and sealed. Then, the panels
36
are riveted together by hand, where one person stands on a platform (not shown) outside the fuselage, inserting and then pneumatically driving a rivet fastener while another person stands inside the fuselage, bracing a large bucking bar against a rivet shank and holding it in place by leaning against the bucking bar with his shoulder. Obviously, such a process presents a risk of injury. Further, the manual process results in rivets that were unevenly deformed, poorly seated, or riveted too close to an edge of the lap joint
48
.
Unfortunately, the manual process is dangerous, time-consuming, expensive and often leads to extensive rework. Consequently, there is a need in the art for a fastening system that speeds up production, ensures riveting and drilling accuracy, eliminates the required step of disassembling the entire fuselage to de-burr, clean and seal, and can be operated within the final fuselage assembly
42
.
SUMMARY OF THE INVENTION
According to one aspect of the invention, a tool position detection assembly aligns a tool relative to a feature within a lap joint of a first panel and a second panel. The detection assembly includes an indexing device engageable to the feature. The indexing device includes a reflecting member having a width. The assembly also includes an end-effector movable along at least one axis parallel to the lap joint for positioning the tool. The end-effector has a dual laser device for detecting when the device is aligned with the reflecting member.
According to another aspect of the invention, a position homing sensor assembly homes a bucking bar module relative to a coordination hole used in the alignment of a lap joint formed by
Banks David P.
Buttrick Jr. James N.
Glaisyer Charles H.
Jones Darrell D.
McCrum Russell C.
Allen Stephone B.
Nelson Lawrence W.
The Boeing Company
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