Abstract:
A video inspection system provides capability to view objects not satisfactorily accessible by direct line of sight. The video inspection system includes a fluid ejection nozzle to clear the workpiece area to be inspected, an adjustable focus camera and connections to remote image data processing equipment. The video inspection system includes a sapphire lens cover to protect the optical lens and a tip protection boot to protect the viewing head from damage by contact with the work being inspected.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates generally to video inspection apparatus, and, in particular, to an apparatus for remote visual inspection of objects not accessible by direct line of sight, for example, objects internal to machinery.  
         [0002]     Thorough inspection of industrial equipment, such as turbomachinery components, requires examination of features and surfaces to which there is no direct line of sight or only a poor line of sight. Many of these features and surfaces are highly-stressed, such as internal oil drain holes, compressor spool inner cavities, and retaining hooks. The part geometries and surface inspections for specified coatings, shotpeen coverage and fluorescent penetrant inspection included in drawing requirements are crucial to component performance and/or life. The area to be inspected may be difficult to illuminate or may be contaminated by debris or dust from a manufacturing, surface finishing or other process. Inspection of remote cavities is often needed, and these cavities often trap machining chips, grinding grit, oils, coolants, or other debris created during manufacturing or finishing processes.  
       BRIEF DESCRIPTION OF THE INVENTION  
       [0003]     The video inspection system includes an optical viewing apparatus which can be positioned to provide video imagery of locations which are visually inaccessible or only partially or poorly accessible. The optical viewing apparatus includes a mechanism for delivery of pressurized fluid to clear the workpiece area to be inspected, a light source to illuminate the area and a video camera to capture optical images, convert the images to digital data and provide image data to electronic image data processing equipment. The camera is supported by an adjustable mount within the apparatus to allow adjustment of the camera focus on the workpiece site to be inspected. The optical viewing apparatus has a head which includes a viewing aperture and protective coverings to make the apparatus robust enough to survive wear and tear from normal use. A fluid spray feature may be included for clearing the surface of the viewing aperture. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]      FIG. 1  is a schematic illustration of one embodiment of a video inspection system of the present invention;  
         [0005]      FIG. 2  is a partial schematic view of the viewing head of the system shown in  FIG. 1 ;  
         [0006]      FIG. 3  is a schematic cross-sectional view of the viewing head shown in  FIG. 2 ;  
         [0007]      FIG. 4  is a schematic cross-sectional view of the video inspection system shown in  FIG. 1 ;  
         [0008]      FIG. 5  is a schematic cross-sectional view showing an alternative embodiment of the invention;  
         [0009]      FIG. 6  is a schematic view showing another alternative embodiment of the invention; and  
         [0010]      FIG. 7  is a schematic showing of one example of an embodiment of an inspection system in use. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0011]     One exemplary embodiment of a video inspection system is shown schematically in  FIG. 1 . The video inspection system  10  includes a first hollow generally cylindrical, elongated tube  12  of a first diameter, a second hollow generally cylindrical, elongated tube  14  having a second diameter larger than the diameter of tube  12 , and a hollow generally frusto-conical tube  16  connected at respective ends thereof to tubes  12  and  14  in coaxial alignment about axis  17  to form a closed tool body  15  of metal or other suitable material. A rotatable collar  18  is threaded to tube  14  and is connected to frusto-conical sleeve  20  which is connected to hollow, cylindrical sleeve  22 . At one end  11  of tube  12  is an viewing aperture  24  through the cylindrical sidewall  26 . The use of a small diameter tube  12  and larger diameter tube  14  are selected to facilitate insertion through small openings into inspection sites and convenient handling by the operator. Other tube diameters may be selected, for example identical diameter tubes may be selected to eliminate the need for frusto-conical tube  16 .  
         [0012]     As shown in  FIGS. 2 and 3  viewing head  28  includes viewing aperture  24 , a light source, such as first illumination aperture  30  and second illumination aperture  32 , and optical lens  34 . A first fluid ejection nozzle  36  is located adjacent the optical lens  34  to direct fluid outward from said tool body toward a workpiece site to be inspected, and second fluid ejection nozzle  38  passes through sidewall  26  in a direction generally aligned with axis  17 , and is located adjacent the viewing aperture  24  to eject fluid generally parallel to axis  17  and along the surface of optical lens  34 .  
         [0013]     As shown in the  FIG. 4  cross section, optical fibers  40  provide a light source to the illumination apertures  30 ,  32  to emit light toward an object in optical alignment with the optical lens  34 . A fluid supply tube  42  extends through sleeve  22  and connects a gas source (not illustrated) to the interior plenum chamber  19  of the tool body  15  and to fluid ejection nozzles  36  and  38 . A light tube  46  is mounted within tool body  15  and is held in fixed axial position relative to cylindrical sidewall  26  within elongated tube  12  by spiders  61 ,  63  to orient angled surface  47  in optical alignment with optical lens  34  to facilitate capture of images of the object to be inspected. A miniature digital camera  44  is mounted in optical alignment with one end  74  of light tube  46  within the tube  12  on camera mount  45 , which is supported by tube  41  and base  49  mounted within sleeve  55  in fixed position relative to frusto-conical sleeve  20 . Base  49  and sleeve  55  are sealed by  0 -ring  57  to allow relative movement between base  49  and sleeve  55  but prevent leakage of fluid into or out of plenum chamber  19 . The tube  14  and rotatable collar  18  are connected by thread  53 . Light tube  46  is adjustable axially by rotation of collar  18 , which moves the elongated tube  12  and light tube  46  axially relative to base  49  and camera  44  to position the end  74  of light tube  46  relative to camera  44 . A translucent boot  50  of rubber or some other suitable material is fitted over the end  11  of tube  12  with cut-out window  52  aligned with port  24 . A sapphire lens cover  56  and mounting strap  58  are secured to end  11  of tube  12  by translucent boot  50 . The translucent boot  50  encloses cover  56  and mounting strap  58  and protects the viewing head  28  from abrasion or other damage.  
         [0014]     When in use the tool body  15  is positioned by the operator so that viewing aperture  24  is located adjacent to components of a workpiece to be examined. The camera is activated to capture video or still images. The focus of camera  44  may be adjusted by rotation of collar  18  relative to tube  14 , which moves base  49  and camera  44  axially within tube  14  toward or away from the end  74  of light tube  46 . The base  49  is maintained in alignment with axis  17  by pin  92  attached to sleeve  55  and slot  94  in base  49 . This allows precise focus of the camera upon the workpiece surface to be inspected. Images of the workpiece are transmitted by light tube  46  to camera  44 , which translates the images into digital image data and transmits the image data via data cable  48  through tool body  15  to external image processing equipment (not illustrated) for display, storage, image enhancement or other processing at the option of the operator.  
         [0015]     During use of the video viewing apparatus of  FIG. 4 , a gas may be supplied via fluid supply tube  42  to pressurize the plenum chamber  19  to provide a gas stream to first fluid ejection nozzle  36  to clear the workpiece site to be viewed and to simultaneously supply another gas stream to second fluid ejection nozzle  38  to clear dust or other material from the optical lens  34 . The gas may be air or inert gas or another gas compatible with the workpiece site to be examined. The gas may be provided in a single blast or a plurality of blasts prior to, or simultaneously with, optical examination of the workpiece site.  
         [0016]      FIG. 5  schematically illustrates an alternative embodiment of the video inspection system. The tool body  15  is the same as in the embodiment of  FIG. 4 . A first fluid supply tube  82  passes through base  84  and is connected to a fluid supply (not shown) separate from the fluid supply source connected to tube  82  and is connected in flow communication with first fluid ejection nozzle  88 . A controlled flow of fluid is supplied via first fluid supply tube  82  to first fluid ejection nozzle  88  which fluid may be air, inert gas or another gas, or may be water or other liquid, such water having a detergent or other solvent. The operator may activate the flow to nozzle  88  to remove debris, oil, dust or other contaminants from the workpiece area to be viewed. A second fluid supply tube  80  passes through base  84  and is connected to a fluid supply (not shown) and is connected in flow communication with second fluid ejection nozzle  86 . The operator may activate the flow through tube  80  to spray fluid, such as air, inert gas, some other gas, or a liquid, such as water or other liquid including detergent or other solvent to remove debris, dust or other contaminants from the optical lens  34  to ensure a clear view. The other components are as shown in  FIG. 4 . The  FIG. 5  arrangement using separate sources of fluid for the lens spray and the workpiece spray allows the operator to control fluid ejection to clear the workpiece area to be inspected separately from fluid ejection to clear the lens. The operator may select the type of fluid and the number and sequence of steps to spray gas or liquid to clear optical lens  34 . The operator may also select the gas or liquid to be used to clear the workpiece based on the material of the workpiece and of the contaminant to be cleared, which may or may not be identical to the fluid used to clear the workpiece site to be inspected.  
         [0017]      FIG. 6  shows schematically an optical inspection system using an external fluid supply tube  62  for supplying gas or liquid to orifice  90  at the end  11  of the tube  12  to clear the workpiece site to be inspected. The tube  62  is secured to the exterior of the optical viewing apparatus by bands  64 ,  66  and  68 , and boot  50  at the end  11  of the tube  12 . The optical viewing system configuration using the interior plenum chamber  19  configuration of  FIG. 4  with gas blast may be used with external tube  62  to supply supplemental gas or may be used with liquid to clear the workpiece viewing area. This allows the operator to selectively apply a solvent or other cleaning material compatible with the workpiece via external fluid supply tube  62  to a site to be viewed. Alternatively, the optical viewing system configuration shown in  FIG. 5  may use the external tube  62  to provide supplemental site clearing with either gas or liquid. The first fluid supply tube  82  may supply the same fluid as external fluid supply tube  62  or may supply a different fluid simultaneously or separately as needed to clear the workpiece viewing area. This allows the operator to select the fluid to properly clear the area without affecting the internal components of the optical viewing apparatus.  
         [0018]     In use, as shown in  FIG. 7 , the optical viewing system  10  is manually inserted into an aperture  70  to provide access for inspection. The light source is activated to illuminate the area to be inspected, shown as drain hole  72 . Air, inert gas or other suitable gas, or liquid solvent, detergent or other liquid compatible with the material of the workpiece is ejected from the first fluid ejection nozzle  36  and/or nozzle  90  to blow dust, debris or other contaminants from the viewing area. Image data are transmitted from the camera to electronic display systems to store, display, or process the images. The electronic display system typically is used to enlarge, rotate, reverse or otherwise manipulate the image for clear evaluation by the operator. The image may also be stored electronically for immediate or subsequent comparison to a standard image or other images of the same area at separate points in the manufacturing or assembly process of the item being inspected.  
         [0019]     While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.