Work holders – Holder inserted within work aperture – Inserted holder movable relative to work backup
Reexamination Certificate
2003-02-20
2004-12-07
Wilson, Lee D. (Department: 3723)
Work holders
Holder inserted within work aperture
Inserted holder movable relative to work backup
C269S048100
Reexamination Certificate
active
06827345
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to an improved wedge-lock fastener and associated installation and assembly methods and, in one advantageous embodiment, to a wedge-lock fastener designed such that the tongue of the wedge-lock fastener may be completely disposed within a counterbore defined by a workpiece engaged by the wedge-lock fastener.
BACKGROUND OF THE INVENTION
Wedge-lock fasteners are utilized in a wide variety of applications. In a typical application, one or more wedge-lock fasteners are utilized to temporarily secure two or more workpieces together. While the workpieces are temporarily held together by the wedge-lock fasteners, permanent fasteners, such as rivets or the like, may be installed. Thereafter, the wedge-lock fasteners may be removed and reused.
By way of example, wedge-lock fasteners may be utilized during the assembly of an aircraft fuselage. In a traditional structure, stringers are temporarily affixed to the skin with a plurality of wedge-lock fasteners. The stringers are then riveted to the skin and the wedge-lock fasteners are removed from the skin/stringer assembly. Additionally, shear ties are temporarily secured to frames with a plurality of wedge-lock fasteners. After riveting the shear ties to the frames, these wedge-lock fasteners are also removed. The skin/stringer assembly is then temporarily fastened to the frame/shear tie assembly, such as by means of a plurality of wedge-lock fasteners. The skin/stringer assembly is then riveted to the frame/shear tie assembly, such as by riveting the shear ties to the skin. Thereafter, the wedge-lock fasteners may again be removed. Finally, stringer clips may be temporarily fastened to the frames and the stringers. After riveting the stringer clips to both the stringers and the frames, the wedge-lock fasteners may be removed. Thus, wedge-lock fasteners or other temporary fasteners may be repeatedly utilized during a number of the steps of the conventional process for assembling an aircraft fuselage.
While wedge-lock fasteners work well in a number of situations, a wedge-lock fastener is unsuitable for certain applications, as described below in conjunction with the conventional wedge-lock fastener
10
depicted in FIG.
1
. As shown, a conventional wedge-lock fastener includes a shank
12
that extends lengthwise between a forward end
14
that is adapted to be placed in contact with one of the workpieces
16
to be clamped together, and an opposed rear end
18
. The shank defines a central passage
20
opening through both the forward and rear ends. The wedge-lock fastener also includes a tong assembly extending lengthwise through the passage defined by the shank. The tong assembly includes a pair of tongs
22
extending through the opening defined by the forward end of the shank. In addition, the forward end of each tong includes a barb
24
extending laterally outward and defining a shoulder
26
for engaging a workpiece as described below. A tong assembly also includes a threaded portion
28
disposed rearward of the pair of tongs. The wedge-lock fastener also includes a tong nut
30
secured to the rear end of the shank and adapted to threadably engage the threaded portion of the tong assembly. Thus, the pair of tongs may be controllably advanced and withdrawn relative to the shank by the rotation of the tong nut relative to the shank.
A conventional wedge-lock fastener
10
also includes a grommet
32
that is sized to fit snugly within the passage
20
defined by the shank
12
. The grommet
32
may be shrink-fitted, crimped, or may be an integral part of the tong assembly. In addition, the interior wall of the shank and the exterior surface of the grommet include lengthwise extending ribs and grooves that cooperate to guide the tong assembly in a lengthwise direction within the passage defined by the shank and to prevent rotation of the tong assembly relative to the shank. The grommet and associated grooves vary in shape and may be hexagonal or polygonal as well. The wedge-lock fastener also includes a tongue
34
disposed between the pair of tongs
22
and extending through the opening defined by the forward end
14
of the shank. The wedge-lock fastener typically includes a tongue retainer ring
36
disposed within the passage defined by the shank so as to effectively retain the rear end of the tongue within the shank and, in particular, between the forward end of the shank and the retainer ring.
During installation through the aligned holes defined by two or more workpieces
16
, the tongs
22
are advanced relative to both the shank
12
and the tongue
34
by rotation of the tong nut
30
with respect to the shank. The tongs are extended such that the tongs extend beyond the tongue, thereby permitting the barbed forward ends
24
of the tongs to be collapsed or displaced toward and into contact with one another. The respective forward ends of the tongs and the tongue may then be inserted through the hole, which has a diameter slightly larger than the width of the barbed forward ends of the tongs once the barbed forward ends of the tongs have been collapsed or displaced toward and into contact with one another, but smaller than the width of the barbed forward ends of the tongs once the barbed forward ends of the tongs are separated by the tongue as described below.
In order to clamp a pair of workpieces
16
together, corresponding holes defined by the workpieces are aligned, and the respective forward ends of the tongs
22
and the tongue
34
are inserted through the aligned holes while the barbed forward ends
24
of the tongs are extended beyond the tongue and deflected toward one another. The tong nut
30
is then rotated in the opposite direction relative to the shank
12
so as to retract the tong assembly. The tong assembly is retracted until the workpieces are snugly engaged on one side by the forward end
14
of the shank and on the other side by the respective shoulders
26
defined by the barbed forward ends of the tongs. During the process of retracting the tongs, the barbed forward ends of the tongs draw alongside the tongue so as to spread the barbed forward ends of the tongs apart and into engagement with the workpiece, as shown in FIG.
1
.
While a conventional wedge-lock fastener
10
provides for the secure engagement of two or more workpieces
16
as shown in
FIG. 1
, difficulties arise if one or more additional workpieces must be placed on or otherwise assembled with the workpieces that are clamped together by the wedge-lock fastener. As will be noted in
FIG. 1
, not only do the barbed forward ends
24
of the tongs
22
extend beyond the surface of the workpieces, but the tongue
34
can extend beyond the surface of the workpieces by a significant distance, depending upon the relative thickness of the workpieces. In order to accommodate the protrusion of the barbed forward ends of the tongs and the tongue beyond the surface of the workpieces, the additional workpiece that is to be placed thereupon may also define an opening through which the barbed forward ends of the tongs and the forward end of the tongue may extend. Especially for workpieces of a relatively large size, however, it may be difficult to place the additional workpiece upon the workpieces that are clamped together with the wedge-lock fasteners without scratching the additional workpiece with the protruding tongues of the wedge-lock fasteners.
By way of a more specific example, an alternative process for assembling aircraft fuselages is being developed. In this process, the stringers and frames are first temporarily fastened together with one or more wedge-lock fasteners or other temporary fasteners. In this regard, the frames define a number of mouse-holes in which the throat of the mouse-hole is smaller than the remainder or body of the mouse-hole. Generally T-shaped stringers are positioned relative to the frames so as to extend through respective mouse-holes defined by the frames. The relatively constricted throat of the mouse-holes is too narrow to simultaneously insert
Anderson Matthew L.
Koch William J.
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