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.

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.