Abstract:
The calibration device includes a guide surface and an angle gauge supported relative to the guide surface on a first side of the guide surface. The angle gauge is adjustable to measure a skew angle of the ultrasonic transducer on the guide surface. The angle gauge is slidable along a length of the guide surface. The angle gauge is rotatably supported parallel to the guide surface. A gauge block rotatably supports the angle gauge.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to calibration reference blocks, and more particularly a reference block for calibrating a skew angle of an ultrasonic transducer.  
       BACKGROUND OF THE INVENTION  
       [0002]     An ultrasonic transducer emits an ultrasonic sound beam incident to a material. The ultrasonic beam is reflected back as an echo from a reflector. The echo response can indicate characteristics of the path traveled. The ultrasonic beam can be steered to a desired point in space by programming an induced angle and a skew angle. The ultrasonic transducer emits the ultrasonic beam corresponding to the programmed induced and skew angles.  
         [0003]     The ultrasonic transducer is used to evaluate and inspect non-observable, internal conditions of structures. In some instances, the ultrasonic transducer is used to evaluate wall thickness of piping, weld integrity, stress corrosion and/or cracking. The nuclear energy industry, in particular, implements ultrasonic transducers to evaluate various components of a nuclear reactor. Other industries, such as the petroleum and aerospace industries, implement ultrasonic transducers to inspect components for metal cracking, weld integrity and metal thickness.  
         [0004]     Prior to inspecting a component, the ultrasonic transducer must be calibrated. Calibration is used to program appropriate beam angles and to focus the beam at the desired point in space. Traditional reference blocks enable accurate calibration of induced angles only.  
       SUMMARY OF THE INVENTION  
       [0005]     Accordingly, the present invention provides a calibration device to calibrate an ultrasonic transducer. The calibration device includes a guide surface and an angle gauge supported relative to the guide surface on a first side of the guide surface. The angle gauge is adjustable to measure a skew angle of the ultrasonic transducer on the guide surface.  
         [0006]     In one feature, the angle gauge is slidable along a length of the guide surface.  
         [0007]     In another feature, the angle gauge is rotatably supported parallel to the guide surface. A gauge block rotatably supports the angle gauge.  
         [0008]     In yet another feature, a first calibration surface is formed in the first side of the guide surface. The ultrasonic transducer rests on the guide surface to transmit ultrasonic waves to the first calibration surface.  
         [0009]     In still another feature, a second calibration surface is formed in the first side of the guide surface. The ultrasonic transducer rests on the guide surface to transmit ultrasonic waves to the second calibration surface.  
         [0010]     In another feature, the angle gauge is movable to be supported parallel to the guide surface on a second side of the guide surface. A calibration surface is formed in the second side of the guide surface. The ultrasonic transducer rests on the guide surface to transmit ultrasonic waves to the calibration surface.  
         [0011]     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0013]      FIG. 1  is a front perspective view of a calibration device;  
         [0014]      FIG. 2  is a rear perspective view of the calibration device;  
         [0015]      FIG. 3  is a front elevation of the calibration device;  
         [0016]      FIG. 4  is a rear elevation of the calibration device;  
         [0017]      FIG. 5  is an exploded view of an angle gauge of the calibration device;  
         [0018]      FIG. 6  is the front elevation of  FIG. 3  illustrating the calibration device with the angle gauge removed and an ultrasonic transducer placed on the calibration device; and  
         [0019]      FIG. 7  is a plan view of the calibration device illustrating alignment of the angle gauge with the ultrasonic transducer. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]     The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0021]     Referring now to  FIGS. 1 through 4 , a calibration device  10  is shown. The calibration device  10  includes a calibration block  12  and an angle gauge  14  slidably attached thereto. The calibration block  12  includes a top guide surface  16 , a bottom guide surface  18 , a front face  20  and a back face  22 . In accordance with one configuration, the angle gauge  14  is mounted to a groove  21  and is slidable across the front face  20  (see  FIG. 1 ). In accordance with another configuration, the angle gauge  14  is mounted to a groove  23  and slidable across the back face  22  (see  FIG. 2 ).  
         [0022]     The calibration block  12  further includes a plurality of calibration or reflector surfaces. The reflector surfaces are arcuate in form, each having a defined radius. Although the reflector surfaces are arcuate, it is appreciated that the reference surfaces can each be formed in other shapes based on the geometry of a component to be inspected.  
         [0023]     A first reflector surface  24  is defined by a first radius (r 1 ) and a second reflector surface  26  is define by a second radius (r 2 ). A front edge  28  of the top guide surface  16 , a front edge  30  of the bottom guide surface  18  and edges  32 , 34  of the first and second reflector surfaces  24 , 26 , respectively, define boundaries of the front face  20 . A third reflector surface  36  is defined by a third radius (r 3 ) and a fourth reflector surface  38  is defined by a fourth radius. A fifth reflector surface  40  is defined by a fifth radius (r 5 ). A back edge  42  of the top guide surface  16 , a back edge  44  of the bottom guide surface  18  and edges  46 , 48 , 50 , of the third, fourth and fifth reflector surfaces  36 , 38 , 40 , respectively, define boundaries of the back face  22 .  
         [0024]     With reference to the front face  20 , a first scribed line  52  indicates the center point of the first radius. A second scribed line  54  indicates the center point of the second radius. A first index hole  56  is bored in the front face  20  adjacent the second reflector surface  26 . A series of scribed angle lines  58  extend at varying angles from the first index hole  56  to the front edge  28 . A first angle line extends at 40°, a second angle line extends at 50° and a third angle line extends at 60°, each relative to vertical. It is appreciated, however, that the particular angles of the scribed angle lines  58  can vary as design requirements dictate.  
         [0025]     With reference to the back face  22 , a third scribed line  60  indicates the center point of the third radius and a fourth scribed line  62  indicates the center point of the fourth radius. A fifth scribed line  64  indicates the center point of the fifth radius. A second index hole  66  is bored into the back face  22  adjacent the third reflector surface  36 .  
         [0026]     Referring now to  FIG. 5 , the angle gauge  14  includes a slide plate  70  to which a dovetail rail  72  and a support  74  are attached. The dovetail rail  72  seats within a groove  76  of the slide plate  70  and is fixed therein by fasteners  78 . The support  74  is fixed adjacent to a face  80  of the slide plate  70  by fasteners  82 . The support  74  includes a bore  84  and an indicator arm  86  having a scribed line  88 . An angle plate  90  is rotatably supported on the support  74 . A flared side of the dovetail rail  72  seats within either of the grooves  21 ,  23  to enable sliding of the angle gauge  14  across the front and back faces  20 ,  22 , respectively.  
         [0027]     A fastener  92  is received through a belleville or spring washer  94  and a hole  96  formed through the angle plate  90 . The fastener  92  is threaded into the bore  84  to secure the angle plate  90  to the support  74 . The spring washer  94  applies sufficient force against the angle plate  90  to prevent undesired rotation of the angle plate  90  about the fastener  92 . When rotation of the angle plate  90  is desired, an operator applies upward force against that of the spring washer  94  and rotates the angle plate  90  about the fastener  92 . The particular angle to which the angle plate  90  is rotated is determined by alignment of the line  88  with angle markers  96  scribed into the angle plate  90 . The angle plate further includes an alignment edge  97  that is aligned parallel to an object for which the angle of is to be determined.  
         [0028]     Referring now to  FIGS. 6 and 7 , use of the calibration device  10  will be described. An ultrasonic transducer  100  is initially programmed with a desired induced angle (α) and a desired skew angle (β) to focus the beam at a point in space. The ultrasonic transducer  100  is set on one of the top or bottom guide surfaces  16 , 18  depending on the particular reflector surface required. The reflector surface is selected based on the geometry of the component. For example, if the component is a pipe with a 2 inch outside diameter, a reflector surface having a 4 inch radius is selected.  
         [0029]     In the exemplary embodiment of  FIGS. 6 and 7 , the ultrasonic transducer  100  is set on the top guide surface  16 . The beam of the ultrasonic transducer  100  is directed toward the second reflector surface  26 . The ultrasonic transducer  100  is slid across and rotated in place on the top guide surface  16  until a desired amplitude response is achieved. The desired amplitude response may be a maximum amplitude response. However, it is appreciated that an amplitude response that is less than the maximum amplitude response may be sufficient for the particular material analysis. In such a case, the desired amplitude response is defined as a sufficient amplitude response. As an example, for an induced angle of 45°, the desired amplitude response is achieved when the ultrasonic transducer  100  is at a 45° angle to the second reflector service  26 . For 45°, the ultrasonic transducer  100  would be approximately aligned with the center point of the radius or the second scribed line  54 .  
         [0030]     Once the desired amplitude response is achieved, the induced angle (α) and the skew angle (β) are confirmed. The induced angle is confirmed using the first index hole  56 . The index holes are perfect reflectors. As a result, the desired amplitude response is easily discerned with the beam directed at the first index hole  56 . The induced angle is confirmed by comparing the position of the ultrasonic transducer  100  with respect to the angle lines  58 . The skew angle is confirmed by aligning the angle gauge  14  with the ultrasonic transducer  100 . The angle plate  90  is rotated until the alignment edge  97  is adjacent and parallel to the ultrasonic transducer  100 . The skew angle is determined by observing the particular angle marker  96  to which the line  88  indicates.  
         [0031]     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.