Title: Optical inspection system and method of use
Abstract: In a preferred embodiment, an optical inspection machine for fasteners, including: an inspection station; a main dial rotatable through the inspection station and carrying thereon a plurality of fasteners; a reflective surface surrounding each of the plurality of fasteners to permit inspection light to reflect from the reflective surface and permit viewing of an entire outer circumference of a head of each of the plurality of fasteners to detect head cracks and bursts; and a lower surface of each of the plurality of fasteners being raised above the reflective surface. A method of optically inspecting fasteners is also provided.
Patent Number: 6,995,837 Issued on 02/07/2006 to Moir, et al.
| Inventors:
|
Moir; Floyd W. (Seymour, CT);
Cressotti; Karl (Cheshire, CT)
|
| Assignee:
|
Retina Systems Inc. (CT)
|
| Appl. No.:
|
775786 |
| Filed:
|
February 10, 2004 |
| Current U.S. Class: |
356/237.1 |
| Current Intern'l Class: |
G01N 21/00 (20060101) |
| Field of Search: |
356/2371,237.2,237.4,237.5
209/586,929,904,907,922,923,652,228,576
|
References Cited [Referenced By]
U.S. Patent Documents
| 3709328 | Jan., 1973 | Mohr et al.
| |
| 5777246 | Jul., 1998 | Woods et al.
| |
| 5823356 | Oct., 1998 | Goodrich et al.
| |
| 5918727 | Jul., 1999 | Wallace et al.
| |
| 6055329 | Apr., 2000 | Mufti.
| |
| 6072583 | Jun., 2000 | Kellner.
| |
| 6285034 | Sep., 2001 | Hanna et al.
| |
| 6762426 | Jul., 2004 | Gilliam.
| |
| 6787724 | Sep., 2004 | Bennett et al.
| |
| 2004/0114113 | Jun., 2004 | Yamada et al.
| |
| 2005/0094861 | May., 2005 | Prakash et al.
| |
Primary Examiner: Toatley, Jr.; Gregory J.
Assistant Examiner: Allawi; Ali
Attorney, Agent or Firm: Crozier; John H.
Claims
What is claimed is:
1. An optical inspection machine for fasteners, comprising:
(a) an inspection station;
(b) a main dial rotatable through said inspection station and carrying thereon
a plurality of fasteners;
(c) a reflective surface surrounding each of said plurality of fasteners to permit
inspection light to reflect from said reflective surface and permit viewing of
an entire outer circumference of a head of said each of said plurality of fasteners
to detect head cracks and bursts; and
(d) a lower surface of said each of said plurality of fasteners being raised
above said reflective surface.
2. An optical inspection machine for fasteners, as defined in claim 1, further
comprising: masks affixed to upper surfaces of said main dial and to a stationary
in-line guide at said inspection station and surrounding said reflective surface.
3. An optical inspection machine for fasteners, as defined in claim 2, wherein:
said masks are spaced apart from said outer circumference by a minimum of about 0.100-inch.
4. An optical inspection machine for fasteners, as defined in claim 1, wherein:
each of said plurality of fasteners is raised above said reflective surface by
about 0.090-inch.
5. An optical inspection machine for fasteners, as defined in claim 1, wherein
each of said plurality of fasteners is raised above said reflective surface by
a land having a width dimension at least about 20 percent less than a corresponding
width dimension of a head of said fastener.
6. An optical inspection machine for fasteners, as defined in claim 2, further
comprising: a reflective guide plate affixed to an undersurface of said in-line
guide to reflect inspection light past a portion of a head of each of said plurality
of fasteners.
7. An optical inspection machine for fasteners, as defined in claim 6, wherein:
said reflective guide plate underlies said main dial by a minimum of about 0.060-inch.
8. A method of optically inspecting fasteners, comprising:
(a) providing an inspection station;
(b) providing a main dial rotatable through said inspection station and carrying
thereon a plurality of fasteners;
(c) providing a reflective surface surrounding each of said plurality of fasteners
to permit inspection light to reflect from said reflective surface and permit viewing
of an entire outer circumference of a head of each of said plurality of fasteners
to detect head cracks and bursts; and
(d) raising a lower surface of said each of said plurality of fasteners above
said reflective surface.
9. A method of optically inspecting fasteners, as defined in claim 8, further
comprising: affixing masks to upper surfaces of said main dial and to a stationary
in-line guide at said inspection station and surrounding said reflective surface.
10. A method of optically inspecting fasteners, as defined in claim 9, further
comprising: spacing said masks apart from said outer circumference by a minimum
of about 0.100-inch.
11. A method of optically inspecting fasteners, as defined in claim 8, further
comprising: raising each of said plurality of fasteners above said reflective surface
by about 0.090-inch.
12. A method of optically inspecting fasteners, as defined in claim 8, further
comprising: raising each said plurality of fasteners above said reflective surface
with a land having a width dimension at least about 20 percent less than a corresponding
width dimension of a head of said fastener.
13. A method of optically inspecting fasteners, as defined in claim 9, further
comprising: affixing a reflective guide plate to an undersurface of said in-line
guide to reflect inspection light past a portion of a head of each of said plurality
of fasteners.
14. A method of optically inspecting fasteners, as defined in claim 13, further
comprising: placing said reflective guide plate under said main dial by a minimum
of about 0.060-inch.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to optical inspection systems generally and, more
particularly, but not by way of limitation, to a novel optical inspection system
that permits bright 360 degree inspection of the perimeter of the head of a fastener
being inspected and a method of use thereof.
2. Background Art
A problem with conventional optical inspection machines is that, although the
main
dial and the in-line guide are constructed of a reflective material such as delrin
plastic, the inspection light is not reflected well. Furthermore, there is a black
band that tends to interfere with complete inspection of the head of the fastener.
Accordingly, it is a principal object of the present invention to provide
an optical inspection system and method of use that affords a bright 360 degree
view of the perimeter of the head of a fastener being inspected.
It is a further object of the present invention to provide such a system and
method
that is easily and economically implemented.
Other objects of the present invention, as well as particular features, elements,
and advantages thereof, will be elucidated in, or be apparent from, the following
description and the accompanying drawing figures.
SUMMARY OF THE INVENTION
The present invention achieves the above objects, among others, by providing,
in a preferred embodiment, an optical inspection machine for fasteners, comprising:
an inspection station; a main dial rotatable through said inspection station and
carrying thereon a plurality of fasteners; a reflective surface surrounding each
of said plurality of fasteners to permit inspection light to reflect from said
reflective surface and permit viewing of an entire outer circumference of a head
of said each of said plurality of fasteners to detect head cracks and bursts; and
a lower surface of said each of said plurality of fasteners being raised above
said reflective surface. A method of optically inspecting fasteners is also provided.
BRIEF DESCRIPTION OF THE DRAWING
Understanding of the present invention and the various aspects thereof
will be facilitated by reference to the accompanying drawing figures, provided
for purposes of illustration only and not intended to define the scope of the invention,
on which:
FIG. 1 is a top plan view of a fastener as seen on the monitor screen of a conventional
optical inspection machine.
FIG. 2 is a top plan view of a fastener as seen on the monitor screen of an
optical inspection machine constructed according to the present invention.
FIG. 3 is a top plan view of a portion of a conventional optical inspection machine.
FIG. 4 is a top plan view of a portion of an optical inspection machine constructed
according to the present invention.
FIG. 5 is an exploded isometric view of the construction of a portion of an
optical inspection machine constructed according to the present invention.
FIG. 6 is an isometric view of the construction of a portion of an optical inspection
machine constructed according to the present invention.
FIG. 7 is a fragmentary isometric view of part of the fastener holding portion
of a conventional optical inspection machine.
FIG. 8 is a fragmentary isometric view of part of the fastener holding portion
of an optical inspection machine constructed according to the present invention.
FIG. 9 is an exploded isometric view showing the construction of the fastener
holding portion of an optical inspection machine constructed according to the present
invention and showing how a stationary in-line guide fits adjacent the main dial.
FIG. 10 is an isometric view shown the construction of the fastener holding
portion of an optical inspection machine constructed according to the present invention
and showing how an in-line guide fits adjacent the main dial.
FIG. 11 is an isometric view of the in-line guide of a conventional optical
inspection machine.
FIG. 12 is an exploded isometric view of the in-line guide of an optical inspection
machine constructed according to the present invention.
FIG. 13 is a side elevational view, partially in cross-section, of a fastener
in a conventional optical inspection machine.
FIG. 14 is a side elevational view, partially in cross-section, of a fastener
in an optical inspection machine constructed according to the present invention,
the view being taken along line "14—14" of FIG. 10.
FIG. 15 is a side elevational view, partially in cross-section, of a fastener
disposed in an optical inspection machine constructed according to the present
invention and showing the paths of inspection light.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
While the present invention is described with reference to a fastener with
a round head, the present invention is applicable as well to fasteners having any
configuration of head, hexagonal, square, etc., with appropriate changes being
made to the construction of the optical inspection machine.
Reference should now be made to the drawing figures on which similar or
identical elements are given consistent identifying numerals throughout the various
figures thereof, and on which parenthetical references to figure numbers, when
used, direct the reader to the view(s) on which the element(s) being described
is (are) best seen, although the element(s) may be seen on other figures also.
FIG. 1 illustrates a monitor screen
20 on which is shown in top plan
view the head of a fastener
22, the perimeter of the head of the fastener
being inspected for head cracks and bursts. Fastener
22 is suspended from
an opening defined in a circular rotating main dial
30, with the underside
surface of the head resting against the surface of the main dial, and as the fastener
passes through the inspection station, it passes a stationary in-line guide
32
that is disposed close to the main dial
30.
It will be understood that a number of fasteners are so disposed in main dial
30 having been fed thereon by a conventional feeder. If a burst or crack
is detected in the head of fastener
22, the fastener is sent to a reject
bin; otherwise, it is considered to be "good" and is sent to another bin.
A problem with conventional optical inspection machines noted above is that,
although
main dial
30 and in-line guide
32 are constructed of a reflective
material such as delrin plastic, the inspection light is not reflected well. Furthermore,
there is a black band between main dial
30 and in-line guide
32 that
tends to interfere with complete inspection of the head of fastener
22.
FIG. 2 is the same view as FIG. 1, but of a machine constructed according to
the present invention. Here, the perimeter of the circumference of the head of
fastener
22 appears to be seamlessly illuminated through 360 degrees. This
is accomplished as shown on some of the drawing figures described below by raising
the head of fastener
22 above main dial
30 and by adding a reflective
guide plate
50, preferably of the same material as the main dial (neither
the raising of the head or the reflective guide plate shown or clearly shown on
FIG. 2). Black delrin plastic masks
60 and
62 are screwed, respectively,
to main dial
30 and in-line guide
32 (FIG. 1) to limit the amount
of reflected light in the inspection area surrounding the head to increase image
contrast and to create a "back light" appearance of the image.
FIG. 3 is the same as FIG. 1, without fastener
22, and shows opening
70 defined through main dial
30. As seen on FIG. 3 and as seen on
some other figures described below and showing a conventional optical inspection
machine and an optical inspection machine constructed according to the present
invention, the leading edge of opening
70 is rounded to permit fastener
22 (FIG. 1, not shown on FIG. 3) to more easily enter the opening.
FIG. 4 is the same as FIG. 2, without fastener
22, and shows opening
70 defined through main dial
30 and also shows more clearly reflective
guide plate
50 screwed to the bottom of in-line guide plate
32. A
raised arcuate land
80 is provided on which the head of fastener
22
(FIG. 2) rests. Land has a height above the upper surface of main dial
30
of approximately 0.090-inch and has a diameter about twenty percent or more less
than the diameter of the head.
FIGS. 5 and 6 illustrate the construction of mask
60 and main dial
30.
Main dial
30 may be conveniently manufactured in segments, as shown. It
will be understood, however, that the segments of main dial
30 extend 360
degrees in a complete circle.
FIGS. 7 and 8 illustrate in more detail some of the elements shown on FIGS.
3 and 4, respectively.
FIGS. 9 and 10 illustrate in more detail how stationary in-line guide
32,
with reflective guide plate
50 disposed underneath the in-line guide, fits
adjacent main dial
30.
FIG. 11 illustrates in-line guide
32 of a conventional optical inspection
machine and shows that the in-line guide is of solid one-piece construction.
FIG. 12 illustrates in-line
32 of the present invention and shows how
mask
62 and reflective guide plate
50 are screwed to the in-line guide.
FIG. 13 illustrates a portion of a conventional optical inspection machine and
shows fastener
22 with the underside of its head resting on main dial
30
and stationary in-line guide
32.
FIG. 14 illustrates a portion of an optical inspection machine constructed according
to the present invention and shows the inside portion of the underside of fastener
22 resting on land
80 and elevated above the upper surface of main
dial
30. It will be seen from FIG. 14 that the outside portion of the underside
of the fastener does not rest on anything. Reflective guide plate
50 underlies
main dial
30 by about 0.060-inch minimum as shown.
FIG. 15 is identical to FIG. 14, except that FIG. 15 indicates some of the paths
of inspection light and how it is reflected, thus affording a 360 degree bright
view of the perimeter of the head of fastener
22. Rays
90 indicate
the paths of light that illuminate the perimeter of the head of fastener
22
to highlight cracks or bursts therein. Of course, rays
90 combine with similar
rays (not shown on FIG. 15) to illuminate the entire 360-degree perimeter of the
head of fastener
22.
Main dial
30 and in-line guide
32 (FIG. 1) are constructed of
steel for machinability, but light up the same as aluminum when illuminated with
the inspection light.
Masks
60 and
62 (FIG. 2) are constructed of black delrin plastic
for white balance within the monitoring camera. The back of the delrin actually
shows up somewhat darker that the delrin used on a conventional optical inspection
machine. Main dial
30 (FIG. 2) is preferably constructed of Armoloy plated
steel, a chromium plating, but can as well be constructed of white delrin plastic,
or various steel and stainless steel materials. Whatever the material of construction,
the surface should be smooth and shiny to reflect inspection light and preferable
has a surface of RMS 15 or greater.
In the embodiments of the present invention described above, it will be recognized
that individual elements and/or features thereof are not necessarily limited to
a particular embodiment but, where applicable, are interchangeable and can be used
in any selected embodiment even though such may not be specifically shown.
Spatially orienting terms such as "above", "below", "upper", "lower", "inner",
"outer", "inwardly", "outwardly", "vertical", "horizontal", and the like, when
used herein, refer to the positions of the respective elements shown on the accompanying
drawing figures and the present invention is not necessarily limited to such positions.
It will thus be seen that the objects set forth above, among those elucidated
in, or made apparent from, the preceding description, are efficiently attained
and, since certain changes may be made in the above construction without departing
from the scope of the invention, it is intended that all matter contained in the
above description or shown on the accompanying drawing figures shall be interpreted
as illustrative only and not in a limiting sense.
It is also to be understood that the following claims are intended to cover all
of the generic and specific features of the invention herein described and all
statements of the scope of the invention which, as a matter of language, might
be said to fall therebetween.
*
