Abstract:
A blasting apparatus includes a first conduit for directing an abrasive stream to a workpiece, and a second conduit for providing a suction force at an outlet of the first conduit and for sucking away particles, the second conduit being disposed substantially surrounding and in parallel to the first conduit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to Singapore Application No. 10201400211U filed on Feb. 26, 2014 and titled Confined Pencil Blasting Apparatus, the disclosure of which is hereby incorporated by reference in its entirety. 
       FIELD 
       [0002]    The present disclosure relates generally to sand-blasting devices, and, more particularly, to a confined pencil-type sand-blasting device. 
       BACKGROUND 
       [0003]    Foreign object damage (FOD) is a significant issue to aircraft engine operation. Damages caused by FOD can directly and indirectly result in costs to engine operators in terms of flight delays, unscheduled maintenance, etc. Furthermore, FOD can also affect flight safety. Foreign objects can come from many sources. One source of FOD may be engine maintenance. During engine maintenance, grit or sand blasting is widely used to remove sulfur corrosion (sulfidation) on surfaces of various engine components. Conventional grit blasting discharges grit from a nozzle at high velocity without containment. The discharged grit scatters to surrounding areas, and may adhere to engine components. During subsequent engine run/test, adhered grit will fall off and cause FOD to the engine. What is desired is a blasting apparatus that can effectively contain discharged grit. There is also desire to overcome one or more drawbacks of conventional blasting. 
       SUMMARY 
       [0004]    Disclosed and claimed herein is a blasting apparatus. In one embodiment, a blasting apparatus includes a first conduit for directing an abrasive stream to a workpiece, and a second conduit for providing a suction force at an outlet of the first conduit and for sucking away particles, the second conduit being disposed substantially surrounding and in parallel to the first conduit. 
         [0005]    In one embodiment, an opening of the second conduit at an end thereof is circumferential to the outlet of the first conduit. 
         [0006]    In one embodiment, the outlet of the first conduit is withdrawn from the opening of the second conduit by a predetermined distance. 
         [0007]    In one embodiment, the opening of the second conduit is an elastic material. 
         [0008]    In one embodiment, the second conduit is concentric to the first conduit. 
         [0009]    In one embodiment, the second conduit has an elongated portion configured for handheld operation. 
         [0010]    In one embodiment, the blasting apparatus includes a stream generator connected to the first conduit for generating the abrasive stream and a dust collector external to the workpiece for providing the suction force to the second conduit and for collecting the particles sucked in by the second conduit. 
         [0011]    In one embodiment, the blasting apparatus includes a valve for adjusting the abrasive stream, so that an in-flow of the abrasive stream is substantially equivalent to an out-flow of collected particles. 
         [0012]    In one embodiment, the blasting apparatus includes a valve for adjusting the suction force of the dust collector, so that an in-flow of the abrasive stream is substantially equivalent to an out-flow of collected particles. 
         [0013]    In one embodiment, the blasting apparatus includes a switch for controlling the abrasive stream. 
         [0014]    One embodiment is directed to a blasting apparatus including a first conduit for directing an abrasive stream to a workpiece and a second conduit for providing a suction force at an outlet of the first conduit and for sucking away particles, wherein the first conduit is disposed inside the second conduit with an opening of the second conduit at an end thereof being circumferential to the outlet of the first conduit, and the first conduit and the second conduit run substantially parallel to each other. 
         [0015]    In one embodiment, the outlet of the first conduit is withdrawn from the opening of the second conduit by a predetermined distance. 
         [0016]    In one embodiment, the opening of the second conduit is an elastic material. 
         [0017]    In one embodiment, the second conduit is concentric to the first conduit. 
         [0018]    In one embodiment, the second conduit has an elongated portion configured for handheld operation. 
         [0019]    In one embodiment, the blasting apparatus includes a stream generator connected to the first conduit for generating the abrasive stream and a dust collector for providing the suction force to the second conduit and for collecting the particles sucked in by the second conduit, wherein the dust collector does not enclose the workpiece. 
         [0020]    In one embodiment, the blasting apparatus includes a valve for adjusting the abrasive stream, so that an in-flow of the abrasive stream is substantially equivalent to an out-flow of collected particles. 
         [0021]    In one embodiment, the blasting apparatus includes a valve for adjusting the suction force of the dust collector, so that an in-flow of the abrasive stream is substantially equivalent to an out-flow of collected particles. 
         [0022]    In one embodiment, the blasting apparatus includes a switch for controlling the abrasive stream. 
         [0023]    The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, the following description and drawings are intended to be exemplary in nature and non-limiting. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    The drawings accompanying and forming part of this specification are included to depict certain aspects of the present disclosure. A clearer conception of the present disclosure, and of the components and operation of systems provided with the present disclosure, will become more readily apparent by referring to the exemplary, and therefore non-limiting, embodiments illustrated in the drawings, wherein like reference numbers (if they occur in more than one view) designate the same elements. The present disclosure may be better understood by reference to one or more of these drawings in combination with the description presented herein. It should be noted that the features illustrated in the drawings are not necessarily drawn to scale. 
           [0025]      FIG. 1  is a cross-sectional view of a blasting apparatus according to one embodiment of the present disclosure. 
           [0026]      FIG. 2  illustrates operation of a blasting apparatus according to one or more embodiments of the present disclosure. 
           [0027]      FIG. 3  is a block diagram illustrating a grit-blasting system according to one or more embodiments of the present disclosure. 
       
    
    
     DESCRIPTION 
       [0028]    One aspect of the disclosure relates to a blasting apparatus. In one embodiment, a cylindrical suction channel surrounding a nozzle of the blasting apparatus is provided for collecting discharged grit. Embodiments of the present disclosure will be described hereinafter with reference to the attached drawings. 
         [0029]      FIG. 1  is a cross-sectional view of a nozzle of a blasting apparatus  100  according to an embodiment of the present disclosure. The blasting apparatus  100  is a long pencil-like grit-blasting apparatus, which includes a central tube  102  and a conduit  110  concentric to the central tube  102 . In other aspects the conduit  110  has a different outside geometry (facing away from the central tube  102 ) versus the inner geometry (facing toward the central tube  102 ) when taken across a cross-section perpendicular to the center line of the central tube  102 . In one other aspect a cross-section of inner geometry of the conduit  110  is substantially circular. In another aspect, a cross-section of the outer geometry of the conduit  110  is also substantially circular. In other aspects the conduit  110  may possess other geometric cross sections such as generally square or rectangular or oval. The central tube  102  is a conduit for blasting out grit at an outlet  104  which can be about the diameter of a pencil lead for fine work on engine components. The conduit  110  maintains a hollow space  112  surrounding the central tube  102  for sucking away particles including discharged grit and/or particles from the blasted surface. An opening  115  of the conduit  110  is circumferential to and extends further than the central tube outlet  104 . In certain embodiments, the central tube outlet  104  may be recessed in opening  115  of conduit  110 . 
         [0030]      FIG. 2  illustrates an operation of a blasting apparatus, such as apparatus  100  of  FIG. 1 . An exemplary grit  202  is blasted through the tube  102  as indicated by an arrow  204 . Once hitting a surface  210  of a workpiece, the grit  202  loses its forward momentum, and then is sucked away by a vacuum force in the conduit  110  as indicated by an arrow  225 . The vacuum force in the conduit  110  may be constantly provided. The conduit opening  115  comes into contact with the workpiece surface  210 , and substantially seals off the space surrounding the tube outlet  104 , so that the discharged grit  202  is inhibited from scattering to outside of the blasting apparatus  100 . Thus the conduit  110  and the tube  102  form a confined nozzle of the blasting apparatus  100 . 
         [0031]    For better sealing, conduit  110  may be particularly close to the opening  115  and can be made of an elastic material, such as rubber, so that the conduit opening  115  can better conform to a contour of the workpiece surface  210 . 
         [0032]    As shown in  FIG. 2 , while the conduit opening  115  reaches the workpiece surface  210 , the tube outlet  104  still has a small distance  232  labeled “S” to the surface  210 . The distance  232  is in the range of a few millimeters to allow the discharged grit  202  to scatter away without clogging the tube outlet  104 . The distance  232  can be adjusted by sliding the conduit  110  up or down in relative to the tube  102 . In one embodiment, the conduit  110  and the tube  102  can be fastened to each other by vanes (not shown) placed in the hollow space  112  of  FIG. 1 . 
         [0033]    According to embodiments of the present disclosure, the grit in-flow through the tube  102  and the grit&#39;s out-flow through the conduit  110  are monitored. In case the in-flow outpaces the out-flow, there must be grit left in the conduit  110 , on the workpiece surface  210  or escaped to the environment. In response, more suction force should be applied to the conduit  110 . In case the out-flow outpaces the in-flow, then the blasting effect may be nullified by the suction force. In response, the suction force applied to the conduit  110  should be reduced. In both cases, adjusting blasting force to the tube  102 , instead of the suction force, can also achieve the goal of substantially equalizing the grit in-flow and out-flow. In other embodiments, the blasting force and the suction force are synchronized, e.g., increasing the blasting force will automatically cause a proportional increase of the suction force. 
         [0034]      FIG. 3  is a block diagram illustrating a grit-blasting system  300  that supports the presently disclosed blasting apparatus  100 . In one embodiment, the grit-blasting system  300  includes an air dryer  312 , a stream generator  318 , abrasive media container  320 , the confined blasting apparatus  100  and a dust collector  330 . The air dryer  312  provide dried air to the stream generator  318  for preventing power problems. The stream generator  318  pressurizes dry air and supplies it to the tube  102  (shown in  FIG. 1 ) of the confined blasting apparatus  100 . Before reaching the confined blasting apparatus  100 , the pressurized air picks up grit from abrasive media container  320  to form an abrasive stream to be blasted out through the tube  102  onto a workpiece  210 . The stream generator  318  is equipped with an exemplary pressure control valve  319  for adjusting the grit&#39;s in-flow into the blasting apparatus  100 . The dust collector  330  is connected to the conduit  110  (shown in  FIG. 1 ) of the confined grit blast  100 , for sucking away and collecting the discharged grit. The dust collector  330  is also equipped with an exemplary pressure control valve  331  for adjusting the out-flow of grit. When the pressure control valves  319  and  331  are properly set, the grit&#39;s in-flow and out-flow can be substantially equalized, so that there will not be significant amount of the discharged grit being left on the workpiece surface or escaped to the environment. Because the discharged grit are substantially confined to the blasting apparatus  100  according to the embodiment of the present disclosure, the dust collector  330  does not have to enclose the workpiece  210  and can still maintain a clean working environment. 
         [0035]    In one embodiment, blasting apparatus  100  can be made of flexible materials or a structure so that a shank of the blasting apparatus  100  can be bent so that an abrasive stream can be directed to more restricted areas. The blasting apparatus  100  may also be equipped with an on-and-off switch to be easily controlled by an operator. 
         [0036]    While this disclosure has been particularly shown and described with references to exemplary embodiments thereof, it shall be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit of the claimed embodiments.