Article profile checker

A fastener (100) slides down a tube (12) onto one end of a channel (16) formed in a V-shaped block (14). Movement of the fastener (100) along the channel (16) is retarded by two fingers (20, 26). A blade (38) moves along a slot (18) in the bottom of the channel (16) to push the fastener (100) along the channel (16) past a feeler (56). The feeler (56) is attached to a shaft (60) of a rotary transducer (58) to pivot therewith. A linear transducer (50) is actuated by longitudinal movement of the blade (38). The output of the transducers (50, 58) is compared by a computer to a predetermined output to check the profile of the fastener (100). A carriage (68) is moved to bring the infeed end (72) of a conduit (70) adjacent to the outfeed end of the block (14). The blade (38) pushes the fastener (100) into the conduit (70).

DESCRIPTION 
1. Technical Field 
This invention relates to apparatus for checking the profiles of articles 
and, more particularly, to such apparatus in which an article is 
positioned on a path and is engaged by a push member that actuates a 
linear transducer and pushes the article along the path past a rotary 
transducer actuated by a feeler that contacts the article. 
2. Background Art 
There are a number of situations in which there is a need to check the 
profile of an article to verify its identity and/or orientation. One such 
situation is in a system for automatically retrieving fasteners, 
delivering them to an installation site, and installing them. In such an 
automatic system, it would generally be desirable to verify that each 
fastener is properly oriented and, when more than one type of fastener is 
being delivered, that the fastener is of the correct type. An incorrectly 
oriented fastener or a fastener of a wrong type could cause damage to the 
installation equipment or the workpiece in which the fastener is being 
installed. An automatic means for checking the identity and orientation of 
the fastener would be needed in order to take full advantage of the labor 
saving and cost saving aspects of an automated system and enable the 
system to operate at a maximum speed. 
The patent literature includes numerous examples of systems for inspecting 
workpieces. Systems in which the position of a feeler or probe is sensed 
when it contacts a stationary workpiece are disclosed in U.S. Pat. No. 
3,135,055, granted June 2, 1984, to G. L. Butler et al.; U.S. Pat. No. 
3,681,582, granted Aug. 1, 1972, to K. Kimio et al.; U.S. Pat. No. 
3,805,393, granted Apr. 23, 1974, to J. H. Lemelson; U.S. Pat. No. 
3,869,802, granted Mar. 11, 1975, to H. G. Pirner; U.S. Pat. No. 
3,920,971, granted Nov. 18, 1975, to R. C. Bevis et al.; U.S. Pat. No. 
4,136,458, granted Jan. 30, 1979, to F. K. Bell et al.; and U.S. Pat. No. 
4,167,066, granted Sept. 11, 1979, to L. E. Cooper et al. Systems in which 
movement of a probe or stylus that contacts a workpiece is sensed while 
there is relative movement between the workpiece and the probe or stylus 
carrier are disclosed in U.S. Pat. No. 4,074,438, granted Feb. 21, 1978, 
to Y. Takeda; U.S. Pat. No. 4,084,324, granted Apr. 18, 1978, to D. J. 
Whitehouse; U.S. Pat. No. 4,158,917, granted June 26, 1979, to A. 
Tagliavini; and U.S. Pat. No. 4,356,556, granted Oct. 26, 1982, to A. 
Sterki. 
U.S. Pat. No. 3,371,419, granted Mar. 5, 1968, to H. E. Banks et al. 
discloses a gauge for measuring the diameters and detecting out-of-round 
conditions of cylindrical objects. The object is positioned on a spring 
biased idler arm and is rotated by a fixed drive wheel. Movement of the 
idler arm caused by contact with the rotating object is sensed by a linear 
transducer in contact with the arm. 
U.S. Pat. No. 3,470,739, granted Oct. 7, 1969, to H. Takafuji et al. 
discloses apparatus for measuring the shape of sheet-like members. The 
sheet-like workpiece and sensing apparatus are moved relative to each 
other to move the sensing apparatus along the sheet. Rotary and/or linear 
transducers carried by the sensing apparatus sense the gradient of the 
sheet at discrete intervals, and the sensed gradients are used to 
calculate the waviness of the sheet. 
U.S. Pat. No. 4,377,911, granted Mar. 29, 1983, to J. Iida et al. discloses 
an instrument for measuring the contour of a workpiece. A stylus on the 
end of a rotatable arm is pressed against the workpiece, and the arm is 
moved axially. Vertical movement of the stylus caused by contact with the 
workpiece is measured by the rotation of the arm. The measured vertical 
movement and the axial movement of the arm are used to calculate the 
contour of the workpiece. 
The above-cited patents and the prior art that is discussed and/or cited 
therein should be studied for the purpose of putting the present invention 
into proper perspective relative to the prior art. 
3. Disclosure of the Invention 
The subject of the invention is apparatus for checking the profile of an 
article. According to an aspect of the invention, the apparatus comprises 
a push member for engaging the aritcle and drive means for moving the push 
member in a linear direction to push the article along a path. A linear 
transducer is actuated by movement of the push member in said linear 
direction. A feeler is mounted to pivot about an axis and has a free end 
positioned to be contacted by the article as the article moves along the 
path. A rotary transducer is actuated by pivotal movement of the feeler 
about the axis caused by contact with the article. 
Preferably, the apparatus further comprises positioning means for 
positioning the article on the path to be engaged by the push member. The 
preferred embodiment of the positioning means includes guide means for 
guiding the article onto the infeed end of the path, and retarding means 
for retarding movement of the article along the path to enable the article 
to be engaged by the push member. The retarding means may comprise a 
pivotably mounted finger having a free end that extends downwardly and in 
an outfeed direction into the channel. The inclusion of positioning means 
in the apparatus of the invention facilitates integration of the apparatus 
into a fully automated system in which the articles to be checked are 
retrieved and fed to the apparatus by automatic means. The preferred form 
of the positioning means allows the speed of the movement of the article 
when it is contacting the feeler to be accurately controlled by the drive 
means which moves the push member. 
The apparatus preferably includes a block having an upwardly facing channel 
that defines the path and a slot extending longitudinally along the bottom 
of the channel. The push member comprises a blade that extends upwardly 
through the slot into the channel and is movable along the slot to push an 
article in the channel along the path. In the preferred embodiment, the 
block is V-shaped, and the channel is upwardly facing and downwardly 
tapering. This preferred configuration has the advantage of readily 
accommodating articles of various sizes, such as cylindrical members of 
differing diameters. 
A preferred feature of the invention is drive means which comprises a 
reciprocating fluid actuated piston rod. The push member is attached to 
the piston rod to move therewith. The linear transducer includes a shaft 
that extends parallel to and is spaced from the piston rod and that is 
also attached to the push member. 
Another preferred feature of the invention is a rotary transducer that 
includes a shaft that defines the axis about which the feeler moves and 
that is attached to the feeler to pivot therewith. The feeler is in the 
form of a finger that extends downwardly and in an outfeed direction from 
the shaft. Preferably, the free end of the finger is biased into the path. 
In order to be compatible with a fully automated system, the apparatus 
preferably includes means for comparing output from the linear transducer 
and the rotary transducer to a predetermined output, and means for 
transporting the article to a location determined by the results of 
comparing such outputs. The preferred embodiment of the means for 
transporting comprises a carriage and a plurality of conduits each of 
which has an infeed end mounted on the carriage. Drive means moves the 
carriage to selectively position one of the infeed ends adjacent to the 
outfeed end of the path. 
The apparatus of the invention provides a quick and accurate means for 
verifying the identity and/or orientation of an article. The apparatus may 
be readily incorporated into a fully automated system and may be used to 
check articles of various sizes and configurations. The structure of the 
apparatus is relatively simple, compact, and durable. The apparatus is 
substantially unaffected by buildup of debris, such as dust and lubricant 
from the articles being processed, and, thus, can be operated for 
relatively long periods of time without requiring maintenance. The 
apparatus is easy and inexpensive to manufacture, calibrate, and maintain. 
In addition, the operation of the apparatus is relatively simple and 
inexpensive to carry out, and the output of the transducers may be readily 
processed at a reasonable cost by use of a reasonably small computer. 
These and other advantages and features will become apparent from a 
detailed description of the best mode for carrying out the invention that 
follows.

BEST MODE FOR CARRYING OUT THE INVENTION 
The drawings show apparatus that is constructed according to the invention 
and that also constitutes the best mode of the invention currently known 
to the applicant. The apparatus shown in the drawings is designed for 
checking the identity and orientation of fasteners, such as the threaded 
countersink fastener 100 shown in FIGS. 3, 6, and 7. It is anticipated 
that the primary use of the apparatus of the invention will be as a 
fastener checker in an automated fastener installation system. However, it 
is of course to be understood that the apparatus of the invention may also 
be used to check the profiles of other types of articles and may be 
adapted to be incorporated into other types of systems. 
The preferred embodiment of the apparatus of the invention shown in the 
drawings includes a frame 4 on which a guide tube 12 is mounted. A 
suitable mechanism (not shown) conveys fasteners into the tube 12 one at a 
time and, preferably, orients the headed fasteners. An example of such a 
mechanism is the device disclosed in the copending United States patent 
application of the applicant and Daniel A. Hendricks, Ser. No. 797,962, 
filed Nov. 14, 1985. Each fastener slides down through the tube 12 and 
onto the infeed end of a V-shaped block 14. Movement of the fastener along 
the block 14 is retarded by fingers 20, 26, and then the fastener is 
pushed along the block 14 by push means 32 to check the profile of the 
fastener and, in the case of a headed fastener, the orientation of the 
fastener. 
The block 14 is mounted on and extends along the forward portion of the 
frame 4. The block 14 has two opposite walls that form an upwardly facing, 
downwardly tapering channel 16 that defines a path along which the 
fastener is pushed during the sensing operation. A slot 18 extends 
longitudinally along the bottom of the channel 16. A push member or blade 
38 extends upwardly through the slot 18 into the channel 16 and is movable 
along the slot 18 to push a fastener along the channel 16. The apparatus 
includes drive means for moving the blade 38 in a linear direction along 
the slot 18 to push the fastener. 
The preferred embodiment of the push means 32 is most clearly shown in 
FIGS. 2 and 5. The push means 32 includes a double acting pneumatic 
cylinder 34 which reciprocates a piston rod 36. The lower portion of the 
blade 38 is attached to the piston rod 36 to reciprocate with the piston 
rod 36. The connection between the piston rod 36 and the blade 38 is 
accomplished by means of a flat push block 40 and a cylinder fitting 42. 
The free end of the piston rod 36 is received into a suitable opening in 
the rear end of the fitting 42, and the front end of the fitting 42 
engages the block 40. The blade 38 is mounted on and extends upwardly from 
the front portion of the block 40. FIGS. 2 and 5 show the piston rod 36 
and the attached blade 38 in a retracted position. When the cylinder 34 is 
activated to move the blade 38 in a forward or outfeed direction to move a 
fastener along the channel 16, the blade 38 slides into and along the slot 
18. The block 40 is attached to a guide member 6 by fastening means 8. The 
guide member 6 slides along the frame 4 beneath the slot 18. 
The longitudinal movement of the piston rod 36 and the attached blade 38 
actuates a linear transducer 50. The output of the transducer 50 provides 
a measure of the axial position of the blade 38 and a fastener being 
pushed thereby. Transducer 50 includes a rod 52 that extends parallel to 
and is spaced below the piston rod 36. The rod 52 is attached to the blade 
38 via a rod fitting 46, a vertical pin 44, and the push block 40 on which 
the blade 38 is mounted. This connection and the connection between the 
piston rod 36 and the block 40 causes reciprocating movement of the piston 
rod 36 to create corresponding movement of the rod 52. The free end of the 
rod 52 is received into a suitable opening in the rod fitting 46. The 
lower threaded end of the pin 44 is threaded into a hole in the rod 
fitting 46 and is secured to the fitting 46 by a nut 48. The upper 
threaded end of the pin 44 threadedly engages the push block 40 and a 
bushing 49. The bushing 49 is received into an opening 43 in the cylinder 
fitting 42 and functions to prevent the fitting 42 from bearing on the 
threads. 
As noted above, the tube 12 guides a fastener down onto the infeed end of 
the path formed by the V-shaped block 14, and movement of the fastener 
along the path is retarded by two metal fingers 20, 26. The fingers 20, 26 
are most clearly shown in FIGS. 2 and 5. Each finger 20, 26 has an upper 
end that is attached to a shaft 22, 28. Each shaft 22, 28 is pivotably 
mounted on the frame 4 of the apparatus above the V-shaped block 14 and 
extends horizontally perpendicular to the channel 16. The shaft 28 is 
spaced longitudinally in an outfeed direction from the shaft 22. The 
finger 26 is straight and extends downwardly and in an outfeed direction 
from the shaft 28 to position its lower free end in the channel 16 in the 
path of the fastener. The finger 20 extends from the shaft 22 downwardly 
and in an outfeed direction parallel to the finger 26 and then bends to 
extend in a horizontal direction under the shaft 28 toward the finger 26. 
Each shaft 22, 28 is weighted to increase its inertia and provide 
resistance to pivoting of the attached finger 20, 26, to thereby slow 
movement of a fastener contacting the finger 20, 26. In the preferred 
embodiment, the weighting of the shafts 22, 28 is accomlished by securing 
a bolt 24, 30 to each shaft 22, 28. The bolts 24, 30 also serve to return 
the shafts 22, 28 to their equilibrium positions after a fastener clears 
the fingers 20, 26. Stops (not shown) may be provided to limit pivotal 
movement of the finger 20. Preferably, operation of the apparatus is timed 
so that the blade 38 is moved in an outfeed direction to engage a fastener 
as the fastener is being slowed by the fingers 20, 26. Therefore, the 
fingers 20, 26 need only retard movement of the fastener and do not 
necessarily actually stop the fastener. 
The blade 38 engages a fastener that has been slowed by the fingers 20, 26 
and pushes it into contact with and past a feeler or finger 56 which 
pivots in response to contact with the fastener. The pivotal movement of 
the finger 56 actuates a rotary transducer 58. The transducer 58 includes 
a shaft 60 that extends above and laterally across the V-shaped block 14 
parallel to the shafts 22, 28. The upper end of the finger 56 is removably 
secured to the shaft 60 by a suitable fastener 62. The attachment is 
releasable to allow quick and easy replacement of the finger 56 should it 
become worn or damaged. The finger 56 extends downwardly and in an outfeed 
direction from the shaft 60 to position its lower free end in the path 
formed by the channel 16. Pivotal movement of the finger 56 caused by 
contact with a fastener causes a corresponding pivoting of the shaft 60 to 
actuate the transducer 58. The shaft 60 is provided with spring means to 
yieldably resist pivotal movement of the shaft 60 and the finger 56 about 
the axis of the shaft 60 and bias the free end of the finger 56 into the 
path of the fastener. As shown in the drawings, the spring means comprises 
a piano wire spring 64 having one end hooked onto the finger 56 and 
another end attached to a post 66. 
Each of the fingers 26, 56 is preferably in the form of a flat strip of 
steel. The finger 20 is preferably a flat steel strip with an angular bend 
as shown in FIG. 2 and described above. The strips 20, 26 are sufficiently 
rigid to retard the movement of the fastener. The feeler strip 56 is 
sufficiently rigid to resist flexing when it contacts the fastener so that 
pivotal movement of the strip 56 accurately reflects the profile of the 
fastener. 
Preferably, the apparatus of the invention also includes a computer that is 
programmed to compare the output from the linear transducer 50 and the 
rotary transducer 58 to a predetermined output. The predetermined output 
is based on the ideal profile of the type of fastener and fastener 
orientation currently required by the system. If the output from the 
transducers 50, 58 is within preset tolerances of the ideal profile, the 
fastener is transported to a location for further processing. If the 
profile is not within the tolerances, it is removed from the system and 
another fastener is selected and checked. 
FIG. 1 shows the preferred means for transporting the fastener to the 
location determined by the results of comparing the predetermined output 
and the output of the transducers 50, 58. A carriage 68 is positioned at 
the outfeed end of the V-shaped block 14. Passageways from the outfeed end 
of the block 14 to the various locations to which the fastener may be sent 
are provided by a plurality of conduits or tubes 70. Each conduit 70 has 
an infeed end 72 mounted on the carriage 68 and opening onto a face of the 
carriage 68. A pneumatic cylinder 74 moves the carriage 68 to selectively 
position one of the infeed ends 72 adjacent to the outfeed end of the 
channel 16 in the V-shaped block 14. A linear transducer 76 senses the 
position of the carriage 68. In the apparatus shown in FIG. 1, there are 
five conduits 70 provided. Four of the conduits lead to stations in the 
installation part of the system, and the fifth conduit leads to a discard 
location. The former four conduits each receive a different kind of 
fastener. For example, separate conduits may be provided for small slug 
rivets, large slug rivets, headed fasteners with threads, and headed 
fasteners without threads, each of which requires different handling in 
the installation process. 
The operation of the apparatus of the invention should be apparent from the 
above description. In summary, a fastener is introduced into and slides 
down the tube 12 into the channel 16 of the V-shaped block 14. While the 
fastener is being delivered to the apparatus, the controller activates the 
cylinder 74 to move the carriage 68 and bring the infeed end 72 of the 
appropriate conduit 70 for the desired fastener type adjacent to the 
outfeed end of the channel 16. Movement of the fastener along the channel 
16 is retarded by the fingers 20, 26. The controller activates the 
cylinder 34 to move the blade 38 to push the fastener along the channel 
16. FIGS. 6 and 7 illustrate the blade 38 pushing a headed fastener 100 
past the feeler 56. Before the fastener reaches the outfeed end of the 
channel 16, the computer compares the output of the linear and rotary 
transducers 50, 58 to the predetermined output to check the profile and 
orientation of the fastener 100. If the fastener is within preset 
tolerances, the cylinder 34 continues to push the fastener 100 into the 
conduit 70. If the sensed output is not within such tolerances, the 
cylinder 34 is deactivated to stop the fastener at the outfeed end of the 
channel 16, the cylinder 74 is activated to reposition the carriage 68 
with the infeed end 72 of the discard conduit 70 adjacent to the channel 
16, and then the cylinder 34 is reactivated to push the fastener into the 
discard conduit 70. After the fastener has been pushed into the 
appropriate conduit 70, the blade 38 is moved back into its retracted 
position, shown in FIGS. 2 and 5, to prepare the apparatus for receiving 
another fastener. FIGS. 8 and 9 are graphs showing the output profiles for 
two different types of fasteners, a 1/4 inch slug rivet and a 5/16 inch 
threaded bolt, respectively. 
FIG. 10 is a simplified schematic diagram of the data processing and 
control portions of the preferred embodiment of the system of the 
invention. The output of the rotary transducer (RVDT) and the linear 
transducer (LVDT) is fed into an analog to digital convertor which 
communicates with the computer via multibus. The computer in turn 
communicates with a programmable controller. Examples of suitable RVDT and 
LVDT devices are the Schaevitz Model R30D rotary variable differential 
transformer and the Schaevitz Model 3000 DC-D linear variable differential 
transformer, respectively. A bushing is positioned on the shaft of the 
Schaevitz RVDT to modify it for mounting the feeler 56. In the preferred 
embodiment, the analog to digital convertor is an Analog Devices Model 
RTI-711 convertor. The computer that processes the converted output of the 
transducers is provided separately from the programmable controller 
because the programmable controller that is included in the preferred 
embodiment of the system lacks sufficient speed to process the data in the 
time required for proper operation of a fully automated system. The 
preferred embodiment of the computer was chosen for its processing speed 
and is the Omnibyte Model 0B68 K1A 68000 single board computer. The 
computer works in conjunction with and is a slave to the programmable 
controller, which in the preferred embodiment is an Allen-Bradley PLC 2/30 
programmable controller. The computer program for processing the 
inspection data is written entirely in 68000 assembly code. The best mode 
of the program currently known to the applicant accompanies this 
application as an Appendix. 
It will be obvious to those skilled in the art to which this invention is 
addressed that the invention may be used to advantage in a variety of 
situations. Therefore, it is also to be understood by those skilled in the 
art that various changes, modifications, and omissions in form and detail 
may be made without departing from the spirit and scope of the invention 
as defined by the following claims. 
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