Abstract:
An ultrasonic transducer holder with a floating head is disclosed. This transducer holder allows the waterpath of the ultrasonic signal to be maintained over a contoured surface. Maintaining a constant waterpath between a transducer and the piece being inspected allows for inspection of surfaces that normally would not be capable of inspection by prior ultrasonic transducer holders.

Description:
STATEMENT OF GOVERNMENT INTEREST 
       [0001]    The United States Government has certain rights in this invention pursuant to contract number 5117182 between the United States Air Force and United Technologies Corporation. 
     
    
     FIELD OF DISCLOSURE 
       [0002]    The present disclosure generally relates to testing equipment, and more specifically relates to the inspection of equipment and materials immersed in a liquid by ultrasonic signals. 
       BACKGROUND 
       [0003]    Ultrasonic testing has become a popular method for flaw detection in new, as well as in-service, materials and equipment. Such testing can determine the size and position of most flaws in the material and equipment. These flaws can be surface cracks, imbedded cracks, voids in the material, non-uniform or non-desirable density, and the like. This information has allowed technicians to determine whether the inspected equipment is still in working condition and potentially how long the equipment will remain in working condition. 
         [0004]    One industry which has benefitted greatly from ultrasonic testing has been aircraft manufacturing and maintenance. Modern aircraft require high accuracy parts to remain intact during operation, both on the outside and the inside. Such parts may include, but are not limited to, compressor fan blades, turbine fan blades, airfoils, and the like. Flaws in the original manufacture, or due to subsequent damage from use, of such parts could result in the parts not functioning properly and damaging themselves or the rest of the aircraft. Ultrasonic testing allows such potentially harmful flaws to be found before they become dangerous to the aircraft. 
         [0005]    Ultrasonic testing begins with a transducer bombarding the object in question with sound waves. When the sound waves come upon a flaw in the object or the opposite side of the object, the wave is reflected. The transducer receives these reflected waves and turns them into an electrical signal. A computer then converts the electrical signals from the transducer into a graph that shows the size and position of the flaw. 
         [0006]    Sound waves are transmitted better in some liquids, such as water, than in air. Thus, to increase the sensitivity of the scans, the object in question can be immersed in a tank of water or other suitable medium. The transducer is also submerged to create a waterpath, a path between the transducer and the object through the water. 
         [0007]    The transducers are typically held by a transducer holder, which is attached to an actuator by a connection rod. This actuator allows for the transducer holder to be moved in a variety of directions, such as, but not limited to, along an axis parallel to the connection rod and along two axes perpendicular to the connection rod. The actuator may be controlled by a computer operating a pre-programmed algorithm. 
         [0008]    While effective, the ultrasonic testing method is limited by the shape of the object being tested. Typically, the object must be relatively planar and not have complicated surface geometry. Additionally, the waterpath needs to remain constant to get consistent readings from the transducers. Clearly a need has arisen for a mechanism that would allow an operator to use ultrasonic testing to scan objects of more complex shape and design, while maintaining a constant waterpath. 
       SUMMARY OF THE DISCLOSURE 
       [0009]    In accordance with one aspect of the disclosure, an ultrasonic scanning assembly having a transducer holder is disclosed. The transducer holder may include: a floating head connected to an actuator by a connection rod; at least one sliding pin slidably mounted to the floating head; a transducer block having at least one transducer mount and connected to the at least one sliding pin and being slidably mounted to the floating head; and a plurality of feet disposed on a bottom surface of the transducer block. 
         [0010]    In a refinement, the transducer block has a rotational frame rotationally connected to the at least one slider pin and has a first rotational axis. 
         [0011]    In a further refinement, the transducer block is rotationally connected to the rotational frame and has a second rotational axis perpendicular to the first rotational axis. 
         [0012]    In another refinement, the transducer holder further comprises at least one transducer, each transducer disposed in a transducer mount. 
         [0013]    In another refinement, the actuator is electronically controlled by a joystick. 
         [0014]    In another refinement, the actuator is electronically controlled by a computer running a pre-programmed algorithm. 
         [0015]    In yet another refinement, the transducer holder is submerged in water in an immersion tank during operation. 
         [0016]    In yet another refinement, the at least one transducer mount is oriented such that when a transducer is mounted, the transducer points towards a smooth finished surface disposed on the transducer block. The smooth finished surface may reflect a sound wave emitted by the transducer at a known angle. 
         [0017]    In accordance with another aspect of the disclosure, a transducer holder is disclosed. The transducer holder comprising a floating head and at least one sliding pin. The sliding pin may be slidably mounted to the floating head. The transducer holder may further include a transducer block having at least one transducer mount and connected to the at least one sliding pin and being slidably mounted to the floating head. The transducer holder may further comprise a plurality of feet disposed on a bottom surface of the transducer block. 
         [0018]    In a refinement, the transducer block has a rotational frame rotationally connected to the at least one slider pin and has a first rotational axis. 
         [0019]    In a further refinement, the transducer block is rotationally connected to the rotational frame and has a second rotational axis perpendicular to the first rotational axis. 
         [0020]    In another refinement, there are exactly three feet disposed on the bottom surface of the transducer block. 
         [0021]    In another refinement, the transducer holder further comprises at least one transducer, each transducer disposed in a transducer mount. 
         [0022]    In yet another refinement, the transducer holder is submerged in a tank of water during operation. 
         [0023]    In yet another refinement, the at least one transducer mount is oriented such that when a transducer is mounted, the transducer points towards a smooth finished surface disposed on the transducer block. The smooth finished surface may further reflect a sound wave emitted by the transducer at a known angle. 
         [0024]    In yet another aspect of the disclosure, a method of ultrasonically testing an airfoil is disclosed. The method may comprise the steps of mounting an airfoil to a mount disposed inside an immersion tank; filling the immersion tank with a liquid medium, the immersion tank constructed such that a liquid may be held within the tank and around the equipment mount and having a top surface of the tank open; controlling an actuator, the actuator comprising a connection rod, by a joystick electronically connected to the actuator; and positioning a transducer holder such that a plurality of feet are in physical contact with a surface of the airfoil. The transducer holder may comprise a floating head connected to the connection rod; at least one sliding pin, slidably mounted to the floating head; a transducer block having at least one transducer mount and connected to the at least one sliding pin and being slidably mounted to the floating head; the plurality of feet disposed on a bottom surface of the transducer block; and at least one transducer, each transducer disposed in a transducer mount. The method of ultrasonically testing an airfoil may further comprise moving the transducer holder across the surface of the airfoil such that the plurality of feet are in contact with the surface of the airfoil and a constant waterpath from the at least one transducer to the surface of the airfoil is maintained; and emitting sound waves from the at least one transducer and receiving the sound waves reflected by a flaw and/or surface of the airfoil by the at least one transducer. 
         [0025]    In a refinement, the transducer block has a rotational frame rotationally connected to the at least one slider pin and has a first rotational axis. 
         [0026]    In a further refinement, the transducer block is rotationally connected to the rotational frame and has a second rotational axis perpendicular to the first rotational axis. 
         [0027]    In another refinement, the actuator is controlled by a pre-programmed algorithm run on a computer electronically connected to the actuator. 
         [0028]    In yet another refinement, the emitted sound waves are directed to the airfoil by a smooth finished surface disposed on the transducer block. The emitted sound waves are reflected by the smooth finished surface at a known angle towards the airfoil. 
         [0029]    These and other aspects and features of the present disclosure will be better understood in light of the following detailed description when read in light of the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]      FIG. 1  is a perspective view of an airfoil being ultrasonically tested by a transducer mounted in a transducer holder constructed in accordance with the present disclosure. 
           [0031]      FIG. 2  is a cut-away side view of a transducer holder constructed in accordance with the present disclosure in contact with an airfoil showing the path of an emitted sound wave. 
           [0032]      FIG. 3  is a perspective view of an immersion tank constructed in accordance with the present disclosure. 
           [0033]      FIG. 4  is a front view of a transducer holder constructed in accordance with the present disclosure. 
           [0034]      FIG. 5  is a perspective view of the transducer holder of  FIG. 5 . 
           [0035]      FIG. 6  is a bottom view of the transducer holder of  FIGS. 5 and 6 . 
       
    
    
       [0036]    It should be understood that the drawings are not necessarily to scale and that the disclosed embodiments are sometimes illustrated diagrammatically and in partial views. In certain instances, details which are not necessary for an understanding of this disclosure or which render other details difficult to perceive may have been omitted. It should be understood, of course, that this disclosure is not limited to the particular embodiments illustrated herein. 
       DETAILED DESCRIPTION 
       [0037]    Referring now to the drawings, and with specific reference to  FIG. 1 , a perspective view of an ultrasonic scan of a piece of equipment, specifically an airfoil  10 , in progress by a transducer  12  mounted in a transducer holder  14  is shown. The airfoil  10  is supported by a mounting  16  inside an immersion tank  18 . The immersion tank  18  can be filled with water or another suitable medium which will allow for a better transmission of sound waves than in air. 
         [0038]    As shown in  FIG. 2 , when an emitted sound wave  22  comes in contact with a flaw/defect  24  the sound wave  22  may be reflected back towards the transducer  12 . The transducer  12  may pick up the reflected sound wave  23  and may convert the wave into a signal which may be transmitted to a computer to be displayed as a graph. 
         [0039]    The graph may be marked with distance marking which correspond to the distance the sound wave  22  traveled before being reflected as well as the horizontal displacement from a designated starting point. Thus, the graph may allow an operator to determine the size and position of the flaw/defect  24  in the airfoil  10 . 
         [0040]    Referring now to  FIG. 3 , an ultrasonic scanning assembly constructed in accordance with the teachings of the present disclosure is shown and generally referred to by reference numeral  36 . As shown, the ultrasonic scanning assembly  36  may be used in conjunction with the immersion tank  18 . The ultrasonic scanning assembly  36  may include an actuator  38  having three degrees of motion for positioning the transducer holder  14  inside the immersion tank  18 . The actuator  38  may have a connection rod  40  which may connect to the transducer holder  14  by a connection thread  42 . 
         [0041]    As shown in  FIG. 4  and  FIG. 5 , the connection thread  42  may be attached to a floating head  44 . The floating head  44  may have a pair of slider holes  46  which may be used by a pair of slider pins  48  connected to a rotation frame  50 . The slider pins  48  may allow the rotation frame  50  to be slidably connected to the floating head  44 . The slider pins  48  may each have a slider cap  52  threadably attached at a top end  54 . The slider pins  48  may further have a bottom end  56  which may each have a hinge  58  connected to the rotation frame  50 . The rotation frame  50  may have free rotation provided by the hinges  58  around a first axis  60  between the pair of slider pins  48 . The rotation frame  50  may further include a second pair of hinges  59  which may connect to a transducer block  62 . Thus, the transducer block  62  may have limited rotation provided by the hinges  58  inside the rotation frame  50  and around a second axis  64  which may be perpendicular to the first axis  60 . The rotation of the transducer block  62  around the second axis  64  is limited by the rotation frame  50 . 
         [0042]    The transducer block  62  may further have at least one mount  66  for at least one transducer  12 . Each transducer  12  may transmit sound waves through the transducer block  62 , through a body of water or other suitable medium, and into the material or equipment being scanned. 
         [0043]    The underside of the transducer block  62  may have a plurality of feet  68  as shown in  FIG. 6 . The feet  68  may keep the transducer block  62  from coming into direct contact with the material or equipment being scanned, such as the airfoil  10 . In one embodiment there are three such feet  68  disposed on the underside of the transducer block  62 . The tree feet  68  define a plane which may provide a stable base for the transducer block  62  when placed onto a surface, such as a surface  70  of the airfoil  10 . While three such feet  68  are shown, this is only exemplary, and any number or shape of feet may be employed. 
         [0044]    In operation, the floating head  44  may be positioned above the surface  70  of the airfoil  10  such that the feet  68  are in contact with the surface  70 . As the transducer holder  14  is moved across the surface  70  by the actuator  38  the sliding pins  48  may allow the transducer block  62  to move up and down with the contour of the airfoil  10  without the need to raise or lower the floating head  44 . The rotational hinges  58  and  59  may allow the transducer block  62  to rotate to the same incline as the surface  70  as the transducer holder  14  moves. Thus, with such rotational and vertical freedom, the transducer holder  14  may be moved across the surface  70  of the airfoil  10  with the feet  68  remaining on the surface, thereby allowing the waterpath between the transducers  12  and the surface  70  to remain constant. 
         [0045]    The actuator  38  may be controlled through a computer by an operator manipulating a joystick. The joystick may give the operator control of the actuator&#39;s three axis motion. Alternatively, the actuator  38  may be controlled by a software program programmed to follow the contours of the airfoil  10  and run on the computer. 
         [0046]    In one embodiment, shown in  FIG. 2 , the transducer mounts  66  may be oriented such that when the transducers  12  are mounted, one in each transducer mount  66 , the sound wave  22  is reflected off of a smooth finished surface  72  at a known calculated angle. The sound wave  22  may be reflected into the surface  70 . The known angle may allow for increased accuracy when interpreting the data collected by the transducers  12  and displayed by the computer. 
       INDUSTRIAL APPLICABILITY 
       [0047]    From the foregoing, it can be seen that the technology disclosed herein has industrial applicability in a variety of settings such as, but not limited to ultrasonic testing of new and in-service equipment and materials. Specifically, the testing of airfoils for use in aircraft is particularly advantageous. The present disclosure may allow the testing of airfoils and other parts with shapes or contours which were previously not possible with prior art testing apparatus. Moreover, the accuracy of the tests is increased by allowing a set of transducers to follow the contour of the airfoil, thereby allowing the transducers to maintain a constant waterpath. 
         [0048]    The transducer block is placed in contact with the surface of the airfoil. When the transducer holder moves over the surface of the airfoil the holder is able to rotate in two directions as well as rise and fall with the contours of the surface to stay in constant contact with the surface of the airfoil. Thus, a constant waterpath between the transducers and the surface of the airfoil is maintained, allowing for more accurate data to be collected by the transducers as well as allowing for testing airfoils with more complicated geometry.