Five axis riveter

Riveting apparatus for operation on a workpiece having opposite sides and supported vertically on a horizontal surface comprising a frame having a pair of spaced apart sides movable along the supporting surface and straddling the workpiece, first and second carriages movably mounted on respective sides of the frame and riveting tools on first and second heads on the first and second carriages, respectively, the tools being movable toward and away from the workpiece. The frame travels in a first direction along the supporting surface and along the workpiece, the first and second carriages are movable in a direction substantially perpendicular to the first direction and toward and away from the supporting surface, and the frame is movable in a third direction transverse to the first direction and toward and away from the workpiece. The first and second heads are movable independently about axes substantially parallel to the first direction and to the supporting surface, and both heads are movable independently about axes substantially perpendicular to the first direction and to the supporting surface. The workpiece is supported by a fixture extending along the path of travel of the apparatus and the fixture is supported at spaced locations therealong above the supporting surface by retractable supports separately movable away from the fixture to provide clearance space between the fixture and the supporting surface for travel of a base of the machine. In a riveting system wherein a plurality of such workpieces are supported vertically on a horizontal surface and arranged in spaced apart parallel rows, there is provided a shuttle carriage extending transverse to the workpiece paths and intersecting the paths for receiving the riveting apparatus and transferring it to any of the other workpiece paths in a manner maintaining the same orientation of the apparatus about a vertical axis during the transfer.

BACKGROUND OF THE INVENTION 
This invention relates to the art of automatic drilling and riveting 
machines, and more particularly to a new and improved automatic drilling 
and riveting machine for operation on major subassemblies. 
One area of use of the present invention is in automatic drilling and 
riveting of vertically disposed workpieces, although the principles of the 
present invention can be variously applied. An example of such a workpiece 
is a contoured wing panel rigidly held vertically in a fixture wherein a 
series of closely-spaced, horizontally disposed stringers are to be 
riveted to the wing panel. Because of the large size and weight of such 
major subassemblies, it is desirable to provide an automatic drilling and 
riveting machine which moves along a stationary workpiece while operating 
thereon. In the design of such a machine, an important consideration is 
providing controlled movement of the drilling and riveting tools in a 
significant number of directions. Another important consideration is 
providing an arrangement for supporting the vertically disposed workpiece 
in a manner which does not interfere with movement and operation of the 
drilling and riveting machine. In addition, it would be highly desirable 
to provide a simple yet effective arrangement for transferring the machine 
between a series of such vertically disposed workpieces for operation 
thereon. 
SUMMARY OF THE INVENTION 
It is, therefore, a primary object of this invention to provide a new and 
improved automatic drilling and riveting machine for operation on major 
subassemblies. 
It is a more particular object of this invention to provide such an 
automatic drilling and riverting machine for movement along a stationary 
workpiece comprising a major subassembly while operating thereon. 
It is a further object of this invention to provide such a machine having 
controlled movement of the drilling and riveting tools in a significant 
number of directions. 
It is a further object of this invention to provide for use with such a 
machine an arrangement for supporting the workpiece in a vertical position 
and in a manner which does not interfere with movement and operation of 
the drilling and riveting machine. 
It is a further object of this invention to provide a simple yet effective 
arrangement for transferring such a machine between a series of vertically 
disposed workpieces for operation thereon. 
The present invention provides riveting apparatus for operation on a 
workpiece having opposite sides and supported on a surface with the sides 
disposed substantially perpendicular to the supporting surface, the 
riveting apparatus comprising 
a frame having a pair of spaced apart sides adapted to move along the 
supporting surface and extending along the workpiece in a manner such that 
the frame sides are in straddling relation to the workpiece, first and 
second carriage means movably mounted on respective sides of the frame and 
riveting tools on first and second head means in first and second 
positioning means on the first and second carriage means, respectively, 
the tools being movable toward and away from the workpiece. 
The apparatus further comprises means on the frame co-operating with means 
on the supporting surface for moving the frame in a first direction along 
the supporting surface and along the workpiece, means on the first and 
second carriage means co-operating with means on respective sides of the 
frame for moving the first and second carriage means in a direction 
substantially perpendicular to the first direction and toward and away 
from the supporting surfaces, and means for moving the frame in a third 
direction transverse to the first direction and toward and away from the 
workpiece. 
The apparatus further comprises means on the first and second head means 
co-operating with means on the first and second positioning means for 
moving the first and second head means independently about axes 
substantially parallel to the first direction and to the supporting 
surface, and means on the first and second positioning means co-operating 
with means on the first and second carriage means for moving the first and 
second head means independently about axes substantially perpendicular to 
the first direction and to the supporting surface. 
In a riveting system wherein the workpiece is supported by a fixture 
extending along the path of movement of the apparatus, the fixture is 
supported at spaced locations therealong above the supporting surface by 
fixture supporting means separately movable away from the fixture to 
provide clearance space between the fixture and the supporting surface for 
travel of a base of the riveting apparatus. 
In a riveting system wherein a plurality of such workpieces are supported 
substantially vertically on a horizontal supporting surface and arranged 
in spaced apart substantially parallel rows, there is provided shuttle 
means extending transverse to the workpiece paths and intersecting the 
paths for receiving the riveting apparatus and transferring it to any of 
the other workpiece paths in a manner maintaining the same orientation of 
the apparatus about a vertical axis during the transfer. 
The foregoing and additional advantages and characterizing features of the 
present invention will become clearly apparent upon a reading of the 
ensuing detailed description together with the included drawing wherein:

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
Referring now to FIGS. 1-3, there is shown riveting apparatus generally 
designated 10 for operation on a workpiece, generally designated 12, 
having opposite sides and supported on a surface generally designated 14 
with the workpiece sides disposed substantially perpendicular to the 
supporting surface. Typically surface 14 is the floor of a building such 
as a factory. In the present illustration, workpiece 12 comprises a 
contoured wing panel rigidly held vertically in a fixture wherein a series 
of closely-spaced, horizontally disposed stringers are to be riveted to 
the wing panel. In particular, as shown in FIG. 1, the wing panel includes 
a wing skin designated 16 which typically comprises a series of sections 
initially joined together in a suitable manner to provide a workpiece of 
significant length. The stringers designated 18 are in closely-spaced 
horizontal relation and held in place prior to riveting the wing skin by a 
series of vertically spaced formers 20 in a manner which will be 
described. The arrangement of wing skin 16, stringers 18 and formers 20 is 
held in a fixtures generally designated 24 in a manner so as to be 
disposed vertically, i.e. such that the opposite sides of the workpiece 
are substantially perpendicular to supporting surface 14. 
The fixture 24 comprises a lower frame member or beam 26 disposed 
substantially parallel to supporting surfaces 14, an upper frame or beam 
28 in spaced, substantially parallel relation to frame 26, and a pair of 
end frame members 30 and 32. In the arrangement shown, the opposite ends 
of fixture 24 are supported on surface 14 by screw jack leveling 
positioners 34 to provide three leveling points on the fixture. In 
accordance with the present invention, fixture 24 also is supported 
intermediate the ends thereof at spaced locations by alignment support and 
correction mechanisms in the form of hydraulic screw jacks 36. Each of the 
retractable supports 36 can be lowered, i.e. moved away from fixture frame 
26 toward surface 14, to provide clearance for travel of riveting machine 
10 along the workpiece in a manner which will be described. A preferred 
form of supports includes an hydraulic cylinder 37 disposed vertically in 
pit 38 extending below surface 14. The workpiece is held in fixture 24 by 
the master tooled header assembly 40 near end 32, by the support members 
generally designated 44 near end 30, and by a series of V-block type 
clamps or holders 46 at spaced locations between the lower and upper 
frames 26 and 28, respectively, and the adjacent edges of the workpiece 
12. Header 40 is made from a master tool so that it will fit its opposite 
header, i.e. to insure that lefthand and righthand counterparts of bulky 
parts such as wing parts fit together. A laser attitude control for 
horizontal/vertical alignment of fixture 24 and workpiece 12 comprises a 
laser light source 50 on frame 26 and a sensor 52 on frame 28, the light 
path therebetween indicated by the broken line 54. 
Machine 10 comprises a frame having spaced-apart sides and adapted to move 
along workpiece 12 in a manner such that the sides of the frame straddle 
the workpiece 12. The machine sides are perpendicular to supporting 
surface 14 and parallel to the sides of workpiece 12. One of the sides of 
machine 10 is defined by a pair of upright, spaced and parallel columns, 
58 and 60 shown in FIG. 1. As shown in FIGS. 2 and 3, the opposite side of 
the machine frame is defined by a pair of spaced apart upright and 
parallel columns 62,64. The machine frame includes a top 66 disposed 
parallel to supporting surface 14 for joining the frame sides, in 
particular, the columns 58,60,62 and 64 at the upper ends thereof as 
viewed in FIGS. 1-3. The machine frame also includes a base or bottom 68 
disposed parallel to and located near supporting surface 14 and supporting 
the columns 58, 60, 62 and 64 at the lower ends thereof. 
The riveting machine frame is adapted to move along track means on 
supporting surface 14 and extending along workpiece 12. In the arrangement 
shown, there is a pair of spaced apart, parallel track rails 70,72 each 
extending along a corresponding side of the arrangement of workpiece 12 
and fixture 24. Movement of machine 10 is guided along rails 70,72 by 
means of wheels, for example, two of which wheels designated 74,76 in FIG. 
1, which are rotatably connected in a suitable manner to base 68 and 
engage the rails 70, 72. One wheel can be sprung hydraulically so that all 
four wheels carry an equal load even though the tracks may be slightly 
misaligned in elevation, i.e. in the verical direction as viewed in FIGS. 
1 and 3. A third rail 80 shown in FIG. 3 extends outwardly of, close to 
and parallel to one of the rails, for example rail 72 and serves as a 
drive rail and power bus. Machine 10 can be driven along rails 70,72 by 
means of a driven pinion on machine 10 engaging a rack on a rail in a 
manner which will be described in more detail presently. Alternatively, 
the wheels may be driven. 
The riveting machine 10 of the present invention further comprises first 
and second carriage means 84 and 86, respectively, movably mounted on 
respective sides of the machine frame. Carrages 84,86 are movable toward 
and away from supporting surface 14 in directions parallel to the sides of 
the machine frame in a manner which will be described. This direction is 
substantially perpendicular to the above-described direction of movement 
of machine 10 along the tracks. The carriages 84 and 86, in turn, support 
and carry first and second positioners 88 and 89, respectively, which in 
turn support and carry first and second block means or head means 90 and 
92, respectively. The heads 90,92 in turn, carry drilling and riveting 
tools for operation on workpiece 12 and are movable relative to the 
respective carriages 84,86 and positioners 88,89 in a manner which will be 
described. 
The machine 10 also is provided with platforms 96 and 98 which extend out 
from the opposite sides for carrying other components of the machine. For 
example, in the machine shown, platform 96 carries an air compressor 100, 
refrigerator-dryer 102 for treatment of the air and an hydraulic pump and 
fluid cooler 104. Platform 98 carries a hopper 106 for storing rivets and 
cabinet 108,110 for housing various controls. 
FIGS. 4-6 are enlarged views of the riveting machine 10 of FIGS. 1-3. The 
heads or blocks 90,92 carry riveting tools and related instrumentalities. 
A rivet bucking tool 116 is mounted on a fixed axis with respect to upset 
head 90 and is adapted to be reciprocated by an hydraulic cylinder 118. 
This axis is the central operating axis, i.e. the drilling and riveting 
axis of machine 10. Movement of bucking tool 116 is toward and away from 
the workpiece, i.e. along a path extending in a direction through the 
sides of the workpiece. The drill/buck/shave or head 92 carries, drilling, 
riveting and shaving tool assemblies. For example the tools can be carried 
on a transfer plate (not shown) adapted to be moved in a direction normal 
to the above-identified operational axis to selectively place the tools in 
alignment with that axis. In the illustration of FIG. 4, the tool shown is 
a shaving tool 120 for smoothing the rivet heads after upset. For a more 
detailed description of an arrangement of linearly spaced drilling and 
riveting tools on a reciprocating transfer plate, reference may be made to 
U.S. Pat. No. 3,534,896 issued Oct. 20, 1970 entitled "Riveting Machine" 
and assigned to the assignee of the present invention, the disclosure of 
which is hereby incorporated by reference. 
The tools carried by the transfer plate are moved by suitable means, such 
as by hydraulic cylinders, toward and away from the workpiece along paths 
which extend in a direction through the sides of the workpiece. A pressure 
foot bushing 124 also is carried by block 92 by means of spaced apart 
pneumatic cylinders 126,128. The bushing 124 is adapted to contact the 
workpiece around the location to be drilled and riveted, and the drilling 
and riveting tools move through a central opening in the bushing for 
contacting the workpiece. For a more detailed description of a pressure 
foot bushing and operation in drilling and riveting apparatus, reference 
may be made to U.S. Pat. No. 3,557,442 issued Jan. 26, 1971 entitled "Slug 
Riveting Method And Apparatus" and assigned to the assignee of the present 
invention, the disclosure of which is hereby incorporated by reference. 
Movement of riveting machine 10 along tracks or rails 70,72 and 80 and 
hence along workpiece 12 in fixture 24 is provided in the present 
illustration by a rack and pinion drive. A gear box 130 carried by base 68 
of the machine frame is driven by a servo motor 132. A pinion 134 on the 
output of gear box 130 meshes with a rack 136 on one of the rails, for 
example rail 72. For a more detailed description of a rack and pinion 
drive for a large riveting machine along a track, reference may be made to 
the aforementioned U.S. Pat. No. 3,534,896. The movement of machine 10 
along the rails and along workpiece 12 is in a direction also designated 
the X axis. The exact location of machine 10 along the X axis is known at 
all times as derived from encoder feedback to the machine control. 
Alternatively, the wheels can be driven directly with periodic 
verification of position. 
Carriages 84, 86 are movable in opposite directions along paths 
perpendicular to the supporting surface 14. These paths are perpendicular 
to the X axis and are identified also as the Y axis. There is provided 
means on the carriage means 84,86 cooperating with means on the respective 
sides of the machine frame for moving carriages 84,86 in the foregoing 
manner. In particular, a pair of ball screws 140 and 142 are provided, one 
on each side of the machine frame and rotatably connected at opposite 
ends, for example, in brackets 144 and 146, respectively, fixed to frame 
top 66 and suitable means (not shown) adjacent frame bottom 68. Nut 
members 148 and 150 are threaded on screws 144 and 146, respectively, and 
engage extensions 152 and 154, respectively, on carriages 84 and 86, 
respectively. Each ball screw and nut assembly is driven by a right angle 
gear box powered by single servo motor, for example the drive indicated 
158 in FIG. 6. The ball screw and nut assembly are matched and preloaded, 
and the carriages 84,86 are synchronously indexed along the Y axis, with 
encoder feedback to the machine control for monitoring the location. The 
arrangement also includes suitable means for counterbalancingthe weight. 
Movement of carriages 84,86 is guided by engagement between rollers 159 on 
carriages 84,86 which ride along tracks 160 on the frame columns. 
Machine 10 further comprises means for moving the frame in a transverse 
direction with respect to the workpiece to move the frame sides toward and 
away from the workpiece. The frame sides are movable in unison in this 
direction, which also is transverse to the direction of the rails 70,72 
and which is designated the Z axis. The combination of columns 58, 60, 62 
and 64 fixed to and depending from top 66 comprises a tied column 
structure. This structure is movably supported on the frame base or bottom 
68 in the following manner. Columns 58, 60, 62 and 64 are provided with 
wheels 162, 164, 166 and 168, respectively, rotatably connected to the 
lower ends of the corresponding columns and contacting supporting surfaces 
on platforms in the form of slides 170, 172, 174 and 176, respectively, in 
frame base 68. The wheel axles are oriented to allow the above-identified 
transverse movement of the tied column structure. The structure is moved 
or indexed by a ball screw and nut assembly driven by a servo generally 
designated 180 in FIG. 4 wherein the ball screw is rotatably connected in 
frame base 68 and the nut member engages a surface of the tied column 
struhcture in a manner similar to that of the Y axis carriage drive. In 
the apparatus shown, the nut member of Z axis drive 180 operatively 
engages the lower end of column 64. Similar Z axis drive arrangements can 
be provided adjacent to the lower ends of the other three columns. 
Machine 10 further comprises means on the first and second head means 90 
and 92, respectively, co-operating with means on the first and second 
positioners 88 and 89, respectively, for moving the first and second head 
means 90,92 independently about axes substantially parallel to supporting 
surface 14 and the X axis. This direction is also designated the a axis 
and is normal to the plane of the paper as viewed in FIG. 4. Thus, each of 
heads 90,92 is pivotal about an axis, i.e. the a axis, generally parallel 
to the X axis. Movement of heads 90,92 is provided by rack and pinion 
drive arrangements in the heads and corresponding positioners. For 
example, as shown in FIG. 4, an arcuate rack 184 on head 90 is in meshing 
engagement with a pinion 186 rotatably mounted on positioner 88 and driven 
by a motorized gearbox 188 on positioner 88. Movement of head 90,92 about 
the a axis in positioners 88,89 is guided by co-operative engagement 
between bearings 190 and arcuate tracks 192 on both of the respective 
components. Only the arrangement on head 90 is shown in FIG. 4 for 
convenience. The gearboxes for both head preferably are driven by servo 
motors which drive the gear segments within established travel limitations 
determined by appropriate sensors, and the a axis travel of each head 
90,92 can be matched through axis calibration at the machine control. 
Machine 10 further comprises means on the first and second positioners 88 
and 89, respectively, co-operating with means on the first and second 
carriage means 84 and 86, respectively, for moving the first and second 
positioners and with them the first and second head means independently 
about axes substantially perpendicular to supporting surface 14 and 
substantially parallel to the Y axis. This direction is also designated 
the b axis and is normal to the plane of the paper as viewed in FIG. 5. 
Thus, each of the positioners 88 and 89 and corresponding one of the heads 
90,92 is pivotal about an axis, i.e. the b axis, generally parallel to the 
Y axis. The positioners 88 and 89, and therefore the heads 90 and 92, are 
supported by trunnions mounted within the carriage 84 and 86, 
respectively, and each positioner 88,89 is driven within the b axis travel 
limits by a d.c. servo motor and ballscrew and nut assembly. In 
particular, as shown in FIGS. 7 and 8, a servo motor 200 is held by a 
trunnion bracket 202 connected to a b axis support beam 203 fixed to 
carriage 86. A ball screw assembly 204 driven by motor 200 is operatively 
associated with a trunnion assembly 206 connected by a bracket 208 to 
positioner 89. An identical arrangement of servo motor 200', trunnion 
bracket 202' , b axis support beam 203 ballscrew assembly 204', trunnion 
assembly 206', and bracket 208' is provided for positioner 88 and carriage 
84. For convenience, only the arrangement for positioner 89 and carriage 
86 will be described in further detail, it being understood that the 
arrangement for positioner 88 and carriage 84 is identical in structure 
and operation. 
FIGS. 9 and 10 are enlarged views showing in further detail the operative 
relationship between ball screw assembly 204 and trunnion assembly 206. A 
nut member 210 on screw 204 has one end within trunnion assembly 206 and 
is housed within a ball nut guard 212. The end of screw 204 opposite motor 
200 is supported within an arrangement of radial bearing 214 and bearing 
housing 216 which can be supported on carriage 86. Trunnion assembly 206 
includes a trunnion plate 220 to which the end of nut 210 is fixed and 
through which screw 204 rotatably extends and a pair of diametrically 
opposed trunnion pins 222 and pin bushings 224 for mounting t5trunnion 
plate 220 within a trunnion ring 226. Another pair of diametrically 
opposed trunnion pins 228 and pin bushings 230, spaced ninety degrees from 
the other pins and bushings, connect trunnion ring 226 to bracket 208. 
Rotation of screw 204 in either direction moves nut 210 to the left or 
right in FIG. 10 to pivot trunnion 206 and bracket to pivot positioner 89 
and with it head 92 about the b axis. 
Movement of heads 90,92 about the b axis in carriages 84,86 is guided by 
co-operative engagement between bearings 234 and arcuate tracks 236 on the 
respective components. Movement of head 90,92 about the b axis can be 
under closed loop sensor control and the travel of each positioners 88,89 
and with them head can be matched through axis calibration at the machine 
control. 
FIG. 11 illustrates in further detail one of the formers 20 in the 
arrangement of FIG. 1. It comprises an elongated board 240 having one side 
242 curved to on conform to the surface of the workpiece, i.e. wing skins 
16, and provided with a series of spaced notches or recesses 244 to 
receive stringers 18. The opposite side of board 240 can be straight. A 
clamp 246 secures skin 16 to board 240 at the upper end of the arrangement 
of FIG. 11 and a V-block member 248 further supports wing skin 16 at the 
lower end. 
FIG. 12 illustrates an alternative arrangement for use in some riveting 
applications wherein the combination of former board 240, wing skin 16 and 
stringers 18 is fastened to a strongback 254 which, in turn, is tightly 
held between upper and lower frames 28' and 26', respectively of a 
fixture. Strongback 254 is in the form of an elongated board having a 
curved side 256 confirming to the curvature of skin 16 and having a 
straight opposite side. Former board 240 is connected to strongback 254 by 
suitable fasteners 258. The overall width of the arrangement of FIG. 12 is 
greater than that of FIG. 11 and is considered in providing the movement 
capability of machine 10 in the Z axis direction. 
Riveting machine 10 of the present invention operaes in the following 
manner. The machine 10 travels along workpiece 12 and fixture 24 in the X 
axis direction as shown in FIG. 1 to move successively to various 
locations on workpiece 12 to be drilled and riveted. During movement of 
machine 10 in this direction, the individual retractable supporting 
cylinders 36 move downward, one-by-one, to surface 14 or below if a recess 
is provided to allow riveter 10 to move to the next location. As the 
machine 10 passes, the particilar cylinder 36 rises to support the 
workpiece once again. In conjunction with movement of machine 10 along the 
X axis, carriages 84,86 are movable along he Y axis to reach additional 
locations to be drilled and riveted. In addition, movement of heads 90 and 
92 about the a and b axes accommodate the surface contour of the workpiece 
12. At each location of fastening, machine 10 goes through the typical 
sequence of drilling the workpiece, rivet insertion and upset, and rivet 
head shaving. Pressure foot bushing 124 and bucking ram 116 contact 
opposite sides of the workpiece 12 and each of the tools is movale into 
alignment with the drilling and riveting axis, toward and away from the 
workpiece and out of alignment with the axis. The foregoing operations are 
well known to those skilled in the art, and for a more detailed 
description thereof, reference may be made to the above-referenced patents 
3,534,896 and 3,557,442. 
By way of example, where workpiece 12 comprises the vertical wing skin 16 
and horizontal stringers 18 shown in FIG. 1, the axis motions of machine 
10 are as follows: X is travel along the wing span, Y is travel along the 
chord length, Z is travel to compensate for chord height, a is rotation 
about the X axis and b is rotation about the Y axis. The X, Y, Z, a and b 
motions allow machine 10 to align the riveting process normal to any point 
on the workpiece within an established work envelope. The X and Y axes can 
be programmable and addressable axes. The Z, a and b motions can be 
controlled by a closed loop normality sensor servo system which traces the 
aerodynamic surface of the workpiece. 
For tool-to-tool alignment, along the drilling and riveting axis, heads 
90,92 can be mechanically geared together vertically through matched ball 
screws, matched right angle gear boxes and a single drive 
motor-gear-reducer-hydraulic counterbalance arrangement. A axis angle 
control can be through a simultaneous signal feed to two servo drives, 
each having an axis calibration supplied by the machine control so that 
slight deviation from the true position can be corrected. B axis angle 
control likewise can be through a second set of servo drives, again 
provided with axis calibration. The a and b axis originate at the work 
outer surface. The origins are held to that point by a Z axis movement 
sensor and associated servo motor and feedback loop. This is so that a 
minor deviation in the a or b attitude will have no effect on the X or Y 
position. 
Machine 10 can move along workpiece 12 in fixture 24 several ways to 
accommodate the presence of formers 20. For example, machine 10 can move 
in the X direction for riveting up to a former, then in the Z direction 
around the former and then in the X direction for continued riveting up to 
the next former and so as along the workpiece 12. The machine 10 can 
return to allow riveting in its location as machine 10 proceeds in the 
return direction. After machine 10 rivets and proceeds away from the 
location of a removed former it is replaced. The removal and replacement 
of formers 20 can be done manually or automatically by machine, either 
under control of riveter 10 or in response to a central control. 
Alternatively, machine 10 can move in a forward X direction for riveting 
up to a former, move in the reverse X direction a small distance to allow 
removal of the former either manually or by machine, then proceed in the 
forward X direction to rivet in the location of the former and beyond 
whereupon the former is returned to its position. 
FIGS. 13 and 14 are diagrammatic views of a riveting system according to 
the present invention including a plurality of riveters identical to 
riveter 10 and a plurality of workpieces and fixtures similar to workpiece 
12 and fixture 24. In the system shown, there are eight workpieces 12a-12h 
supported in eight fixtures 24a-24h. The workpiece and supporting fixtures 
are arranged in four spaced-apart, mutually parallel rows comprising a 
first set, and another, four spaced-apart, mutually parallel rows in 
longitudinal alignment with the first four rows and comprising a second 
set. The workpiece and corresponding fixtures are disposed perpendicular 
to, i.e. vertically, a supporting surface 14'. In the system shown there 
are four riveters 10a, 10b, 10c and 10d each of the type like riveter 10 
of FIGS. 1-10 including a frame having a pair of spaced apart sides 
adapted to move along track means on the supporting surface extending 
along a workpiece in a manner such that the frame sides are in straddling 
relation to the workpiece and carry drilling and riveting tools that are 
movable toward and away from the workpiece. In the present illustration of 
riveting stringers to wing skins, the eight workpieces 12a-12h can 
comprise the left wing rear lower skin, left wing rear upper skin, left 
wing front lower skin, left wing front upper skin, right wing rear lower 
skin, right wing rear upper skin, right wing front lower skin, and right 
wing front upper skin, respectively. The travel path for each riveter 
along each workpiece and fixture is defined by spaced-apart, parallel 
tracks 70a, 72a-70h, 72h. In addition, the tracks of aligned rows are also 
aligned i.e. tracks 70a,72a are in longitudinal alignment with tracks 
70e,72e and so on through the entire arrangement. Along each row there is 
an X axis drive power bars and track 270a-270h, and tracks of aligned or 
opposite rows are aligned, for example tracks 270a and 270e. 
In the illustrative arrangement shown riveters 10a-10d are located on the 
paths containing workpieces 12a-12d, respectively. The system of the 
present invention enables any riveter to be moved to any workpiece and 
fixture area in the arrangement of FIGS. 13 and 14 or to an out of service 
location for maintenance. To this end there is provided shuttle carriage 
means adapted to receive and carry any riveter and movable along means 
defining a shuttle path extending in a direction transverse to and in 
communication with, i.e. intersecting, the workpiece paths. As the riveter 
is received and carried by the shuttle carriage its orientation about the 
Y axis is not changed, and when the destination is reached the riveter 
simply can move off the carriage without changing position and is 
immediately ready for travel along the row where it is left by the shuttle 
carriage. 
As shown in FIG. 14, the shuttle carriage means comprises a carriage 274 of 
welded steel construction which travels within a shallow pit 276 extending 
tranverse to track 70a,72a-72h, to any of the four interface locations 
shown in FIG. 13. For convenience, these four interface location are 
indicated by the representation of shuttle carriage 274 and riveter 10 
shown in broken lines. Carriage 274 is supported by wheel track assemblies 
280 of sufficient size to support the weight of the riveter and be 
electrically driven. To this end, rails 282,284 extend along the bottom of 
pit 276. The top 286 of shuttle carriage 274 is substantially flush with 
supporting surface 14 and is provided with track assemnblies 290,292 and a 
power trolley matching those utilized to facilitate riveter X axis travel. 
The tracks 290,292 are aligned with the tracks 70,72 at each intersection 
point allowing the riveter X axis drive to power directly onto the shuttle 
carriage 274. The carriage 274 has its own controller and operator. As 
shown in FIG. 13, pit 276 extends beyond the rows containing workpiece 
12d, 12h to an out of service shunt location 296 for maintenance or 
storage. If desired, shunt side tracks at location 296 can be provided, 
extending perpendicular to pit 276, for temporary removal of a riveter 
from th shuttle carraige. 
Thus, one riveter can be taken out of service by moving it to the shunt 
section 296, and by replacement of a fixture in place with a workpiece, 
the appropriate riveter can be brought out of the shunt section and moved 
on line using the shuttle carriage 274 to move the riveter to the assembly 
area where used. Although the shuttle or traverse carriage 274 is used 
primarily to move riveters to and from assembly areas and to and from out 
of service or maintenance areas, when empty the shuttle carriage 274 can 
serve as a bridge over the shuttle or traverse pit 276. 
FIGS. 15 and 16 are enlarged views showing in further detail the shuttle or 
traverse carriage 274 and pit 276. As shown in FIG. 15, on the top surface 
286 of carriage 274 is provided with a pair of spaced apart rails 290,292 
onto which a riveter 10 is moved and supported for conveyance by carriage 
274 along the transverse path defined by pit 276. As shown in FIG. 16, 
shuttle carriage is driven by a rack and pinion arrangement including a 
rack 300 on one of the tracks in pit 276, for example track 284, which is 
engaged by a pinion 302 driven by a motorized gear box 304 on carriage 
274. Electric power is supplied by a rail 308. Alternatively, the shuttle 
carriage wheels can be driven directly. 
As previously mentioned, one of the four wheels providing movement of 
fastening machine 10 in the X direction is sprung by flexible supporting 
means, preferably fluid operated, so that the wheel carries its share of 
the load independent of vertical position over a short travel. For 
accurate placement of fasteners, it is of utmost importance that the two 
tracks along which machine 10 travels be parallel in both plan and 
elevation. As shown in FIG. 15, one of the wheels, for example wheel 76, 
is hydraulically sprung so that all four wheels of machine 10 carry an 
equal load even though the tracks 70,72 may be slightly misaligned in 
elevation. Such vertical misalignment can occur over the large extent of 
surface 14 travelling along the length of the workpiece 12. As shown in 
FIG. 15, the wheel bearing assembly and axle 310 are carried by block 
means 312 having a pair of arm-like side members joined by a web to 
provide a fork-like structure which rides up and down between gibs 314 
which are fixed to be stationary with respect to the machine frame. The 
flexible supporting means is in the form of an hydraulic cylinder 316 the 
housing of which is fixed to the machine frame and the piston rod of which 
is connected to block means 312. Cylinder 316 is provided with controlled 
pressure to provide a maximum stroke in the vertical direction of about 
one-quarter inch. 
It is a therefore apparent that the present invention accomplishes its 
intended objects. While embodiments of the present invention have been 
described in detail, that is for the purpose of illustration, not 
limitation.