Abstract:
A system for non-destructively inspecting brazed joints that includes at least one matrix phased array probe that further includes plurality of ultrasonic transducer elements arranged in an array at one end of the probe, wherein the transducer elements are operative to both generate ultrasonic signals and to receive reflections thereof; and at least one tip adapted to be removably mounted over the array of ultrasonic transducer elements, wherein a region of the at least one tip has been shaped to correspond to the geometric characteristics of an item or a specific portion of an item that includes a brazed joint to be inspected; and a processor running software that includes at least one imaging algorithm for processing data received from the at least one matrix phased array probe and generating color coded ultrasonic C-scan images of inspected brazed joints.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/091,869 filed on Dec. 15, 2015 and entitled “Matrix Phased Array System for Inspection of Brazed Welds,” the disclosure of which is hereby incorporated by reference herein in its entirety and made part of the present U.S. utility patent application for all purposes. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates generally to inspection systems for use in assessing the performance of industrial manufacturing processes, and more specifically to a nondestructive inspection system for assessing the quality of brazed joints and fusion or solid state sheet metal joints. 
         [0003]    Sheet metal joining processes are widely used in many industries including the aerospace and automotive industries. Resistance spot welding, seam welding, weld bonding, adhesive joining, soldering, and brazing are used for various applications in different industries. Among these processes, the brazing procedure is used to join metal sheets where good electrical conductivity, as well as mechanical and thermal strength, is required from the joint. The quality control of such joining processes has been recognized as an important issue to manufacturers. The quality of brazed joints is affected by the joining process itself and by the design of the joint. Many factors are considered, including metallurgic reaction conditions; thermal behaviors; chemical composition; starting condition of the base metal; brazing and bonding conditions; and the particular brazing and bonding equipment used during the process. Furthermore, the intricate relationship between these factors makes it difficult to control the quality of the brazed joint and difficult to inspect the weld joint in a nondestructive manner. It is particularly difficult to inspect on-line small areas such as electrical contacts brazed to terminal or arm sheet metal conductors due to the strong geometry and edge effects presented by such items. 
         [0004]    Certain acoustic methods enable nondestructive testing of welded parts that is useful for various inspection applications. Unlike other nondestructive testing methods, acoustic methods provide both surface and internal information about a particular weld joint. Moreover, acoustic methods allow for deeper penetration into test specimens and provide higher sensitivity regarding small discontinuities that may be present in a weld joint. Acoustic methods, however, do have limitations, including the requirement of having a skilled and knowledgeable operator for using a test device and then analyzing acoustic data derived from a test specimen. Accordingly, the field of ultrasonic nondestructive evaluation (NDE) is in need of a reliable process or technique for identifying poor quality brazed joints in a manner that eliminates the requirement of a skilled operator and the subjective interpretation of test data. 
       SUMMARY OF THE INVENTION 
       [0005]    The following provides a summary of certain exemplary embodiments of the present invention. This summary is not an extensive overview and is not intended to identify key or critical aspects or elements of the present invention or to delineate its scope. 
         [0006]    In accordance with one aspect of the present invention, a first system for non-destructively inspecting brazed welds or brazed joints is provided. This system includes at least one matrix phased array probe that further includes a plurality of ultrasonic transducer elements, arranged in an array at one end of the probe, that are operative to both generate ultrasonic signals and to receive reflections thereof; and at least one tip adapted to be removably mounted over the array of ultrasonic transducer elements, wherein a region of the at least one tip has been shaped to correspond to the geometric characteristics of an item or a specific portion of an item that includes a brazed joint to be inspected; and a processor running software that includes at least one imaging algorithm for processing data received from the at least one matrix phased array probe and generating A-scans and color coded C-scan images of inspected brazed joints. 
         [0007]    In accordance with another aspect of the present invention a second system for non-destructively inspecting brazed welds or brazed joints is provided. This system includes a phased array control unit; at least one matrix phased array probe connected to the phased array control unit, wherein the matrix phased array probe further includes a plurality of ultrasonic transducer elements, arranged in an array at one end of the probe, that are operative to both generate ultrasonic signals and to receive reflections thereof; and at least one tip adapted to be removably mounted over the array of ultrasonic transducer elements, wherein a region of the at least one tip has been formed or shaped to correspond to the geometric characteristics of an item or a specific portion of an item that includes a brazed joint to be inspected; a processor running software that includes at least one imaging algorithm for processing data received from the at least one matrix phased array probe and generating A-scans and color coded C-scan images of inspected brazed joints; and at least one monitor for visually displaying the A-scans and color coded C-scan images of inspected joints in real time. 
         [0008]    In yet another aspect of this invention, a third system for non-destructively inspecting brazed welds or brazed joints is provided This system includes a phased array control unit; at least one matrix phased array probe connected to the phased array control unit, wherein the matrix phased array probe further includes a plurality of ultrasonic transducer elements arranged in an array at one end of the probe, wherein the transducer elements are operative to both generate ultrasonic signals and to receive reflections thereof; and at least one tip adapted to be removably mounted over the array of ultrasonic transducer elements, wherein a region of the at least one tip has been shaped to correspond to the geometric characteristics of an item or a specific portion of an item that includes a brazed joint to be inspected; an enclosure that may be portable or that may be designed to be placed on a flat surface and that includes at least one input for connecting to the at least one matrix phased array probe; ultrasonic phased array transmitting and receiving circuitry in electrical communication with the at least one input; and at least one external mount for supporting the matrix phased array probe; a processor running software that includes at least one imaging algorithm for processing data received from the at least one matrix phased array probe and generating A-scans and color coded C-scan images of inspected brazed joints; and at least one monitor for visually displaying the A-scans and color coded ultrasonic C-scan images of inspected joints in real time. 
         [0009]    Additional features and aspects of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the exemplary embodiments. As will be appreciated by the skilled artisan, further embodiments of the invention are possible without departing from the scope and spirit of the invention. Accordingly, the drawings and associated descriptions are to be regarded as illustrative and not restrictive in nature. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The accompanying drawings, which are incorporated into and form a part of the specification, schematically illustrate one or more exemplary embodiments of the invention and, together with the general description given above and detailed description given below, serve to explain the principles of the invention, and wherein: 
           [0011]      FIG. 1  is an exploded view of a matrix phased array probe, in accordance with an exemplary embodiment of the present invention; 
           [0012]      FIG. 2  is a side view of the matrix phased array probe of  FIG. 1 , shown in its assembled state; 
           [0013]      FIG. 3  is cross-sectional side view of the a matrix phased array probe of  FIG. 2 ; 
           [0014]      FIG. 4  is a cross-sectional top view of a section of the matrix phased array probe of  FIG. 2  showing the tip and orientation slot aspects of the matrix phased array probe; 
           [0015]      FIG. 5  is a bottom view of an exemplary embodiment of the matrix phased array probe of the present invention showing the layout and appearance of the sensor array; 
           [0016]      FIG. 6  is a schematic of the sensor array of the matrix phased array probe of the present invention illustrating certain relevant dimensions of the array; 
           [0017]      FIG. 7  is a front view of the tip component of the present invention; 
           [0018]      FIG. 8  is a perspective view of the tip component of  FIG. 7 ; 
           [0019]      FIG. 9  rear view of the tip component of  FIG. 7 ; 
           [0020]      FIG. 10  is a side view of the tip component of  FIG. 7 ; 
           [0021]      FIG. 11  is a side view of the matrix phased array probe of  FIG. 2  in contact with a test specimen having a braze weld joint to be analyzed; 
           [0022]      FIG. 12  is a cross-sectional front view of the assembly of  FIG. 11 ; 
           [0023]      FIG. 13  is a drawing of the matrix phased array NDE system of the present invention; 
           [0024]      FIG. 14  is a close-up drawing of the probe and bracket components of the matrix phased array NDE system of  FIG. 13 ; and 
           [0025]      FIG. 15  is a graphic illustration of an acoustic signal on a C-scan (all elements) and an A-scan (single element) selected on the C-scan. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    Exemplary embodiments of the present invention are now described with reference to the Figures. Although the following detailed description contains many specifics for purposes of illustration, a person of ordinary skill in the art will appreciate that many variations and alterations to the following details are within the scope of the invention. Accordingly, the following embodiments of the invention are set forth without any loss of generality to, and without imposing limitations upon, the claimed invention. 
         [0027]    The present invention provides a matrix phased array (MPA) inspection system for non-destructive (NDE) evaluation of brazed weld joint and other types of weld joints. The exemplary embodiment of this inspection system shown in the Figures and described herein uses high frequency (12 MHz) ultrasonic energy to determine the area of lack of braze (LOB) in flat brazed contacts. This system typically includes the following basic components; (i) a matrix phased array probe; (ii) one or more removable tips that are mounted on the probe during weld joint analysis; (iii) a phased array unit to which the probe is connected; (iv) a processor connected to the phased array unit and running specific software for processing and analyzing data generated by the phased array unit; and (v) a monitor for visualizing A-scans and C-scans generated by the software. The phased array unit and other system components associated with the phased array unit may be assembled in an enclosure that includes a fixed bracket for holding the matrix phased array probe during the evaluation of test specimens. 
         [0028]      FIGS. 1-4  provide various illustrative views of a matrix phased array probe, in accordance with an exemplary embodiment of the present invention. Matrix phased array (MPA) probe  20  includes cylindrical probe housing  22 , threaded region  24 , sensor array  26 , and orientation pin  28 . With reference to  FIGS. 5-6 , in this embodiment, MPA probe  20  includes two-dimensional (2-D) matrix array  26  having the following characteristics: (i) number of channels (Nx×Ny): 14×9 elements; (ii) pitch in primary axis (Px): 0.8 mm; (iii) pitch in secondary axis (Py): 1.0 mm; (iv) inter-element spacing (IEx): 0.1 mm; (v) inter-element spacing (IEy): 0.1 mm; (vi) element height: 0.9 mm; (vii) element width 0.7 mm; (viii) total active area (Lx×Ly): 11.1×8.9 mm 2 ; (ix) center frequency: 12 MHz; and (x) acoustical impedance matching (for tip 40): thermoset cross-linked styrene copolymer tip (e.g., Rexolite®). In other embodiments, the inter element spacing for IEx and IEy is about 0.5 mm. 
         [0029]    As shown in  FIGS. 10 , an exemplary embodiment of plastic cylindrical tip  40  includes base  42 ; orientation slot  44 , which cooperates with orientation pin  28  for properly aligning tip  40  on the end of MPA probe  20 ; tip body  46 , upon which various identifying indicia may be placed; and recess  48 , the geometry of which has been adapted to match or closely cooperate with the shape of a specific flat terminal contact that has been braze welded to a terminal body. As shown in  FIGS. 11-12 , an exemplary part to be inspected  100  includes terminal body  102  and terminal contact  104 , which has a specific geometry that corresponds to the geometry of recessed area  48  in tip  40 . During evaluation, probe  20  is inverted and mounted within bracket  66 , which is typically mounted on one side of enclosure  60 , as shown in  FIGS. 13-14 . Sensor array  26  is coated with acoustic couplant gel, tip  40  is placed over sensor array  26  on MPA probe  20 , and locking member (nut)  50  is tightened onto threaded region  24  to secure tip  40  to the tip of MPA probe  20 . Part  100  is then positioned such that terminal contact  104  is seated within recessed area  48  of tip  40 . Phased array unit (PAU)  61  and sensor array  26  are then activated for the purpose evaluating the braze weld between terminal body  102  and terminal contact  104 . Tip  40 , and particular the shape and other geometric characteristics of recessed area  48 , which is formed in body  46  of tip  40 , may be modified to fit any number of different contacts (or other structures) that a brazed welded to terminal bodies or other items. Accordingly, a great many variants of tip  40  are possible. 
         [0030]    As shown in  FIGS. 13-14 , ultrasonic multi-channel cable  62  with Ipex connector  63  is used for connecting MPA probe  20  to phased array unit  61  (32/128: Advanced OEM Solutions), which is housed within enclosure  60 . Suitable enclosures include Carlon® types 1 and 2, and other components included in the enclosure typically include a cooling fan (e.g., 4″ AC Brushless, 115 VAC, Rotation Speed 2100 RPM, Airflow 65 CFM, 119×119×38 mm, Mounting holes 4.2 mm.); a switch mode power supply (e.g., Model—ETSA240270UD; P/N—ETSA240270UDC-P5P-SZ; Input—100-240V˜, 50-60 Hz, 1.5 A; Output—24V 2.7 A); and a relocatable power tap (e.g., model UTPB 1115 (YLPT-22A); Maximum Load—15 A, 125 VAC, 60 Hz). Serial cable  64  is used to connect phased array unit  61  to processor  70 , which is typically a laptop or desktop computer that is connected to a monitor  90 . Processor  70  runs software that that includes at least one imaging algorithm for processing data received from MPA probe  20  and generating color coded ultrasonic C-scan images of characterized brazed weld, as well as other drivers to control phased array unit  61  and the data acquisition process. An example of suitable imaging software is SpotSight®, which is available from EWI, Inc. (Columbus, Ohio). 
         [0031]    When inspection system  10  is in use, recessed area  48  centers terminal contact  104  with respect to the rectangular area coverage of sensor array  26 . Recessed area  48  permits slight movements along the length and width thereof to maximize LOB indications, if present. If an LOB indication is present that exceeds a predetermined threshold on the A-scan, it will be imaged in red color on the C-scan (see  FIG. 15 ). Indications with amplitude smaller than the predetermined threshold are imaged in blue or other colors. The threshold is adjusted so that only the area of the brazed joint  106  between terminal contact  104  and terminal body  102  is tested and imaged. The elements of MPA probe  20  are interrogated in a predetermined sequence to cover the entire area under the probe. The areas where the signal is larger than the threshold are summed to determine the total LOB area. It is displayed as absolute value in mm 2  and relative percent (%) of the region of interest (see  FIG. 15 ). An area or region of interest is specified for each terminal contact  104  as shown on the C-scan. The MPA area coverage is designed for the largest contact area. Other contacts  104  that are smaller in size are tested by selecting an appropriate tip  40  and recessed area  48  that fits the contact and adjusting the region of interest on the C-scan so that the same probe can be used to test all contact sizes. A single percentage LOB acceptance criterion can be specified for all contacts  104  regardless of their size. The C-scan image with measured LOB is captured and stored for reporting purposes. A determination of weld integrity is based on whether sound passes through the brazed weld or not. Algorithms included in the SpotSight® software assist in generating both an A-scan and a color (red/green/yellow) representation of the welded region, which is a C-scan (see  FIG. 15 ). Each part to be inspected  100  typically receives a custom tip  40  and some applications of this invention utilize a flexible probe membrane. 
         [0032]    Advantageously, exemplary embodiments of the system of the present invention includes (i) a fixed sensor; (ii) numerous tips with recessed areas or slots to guide and center various contacts; (iii) regions of interest are specified on a C-scan; (iv) a single sensor may be used for all contact sizes; (v) a region of interest can also be used when several elements of the MPA probe are grouped to focus and steer the ultrasonic beam for contacts that have curved surfaces as opposed to flat contacts. 
         [0033]    While the present invention has been illustrated by the description of exemplary embodiments thereof, and while the embodiments have been described in certain detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to any of the specific details, representative devices and methods, and/or illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant&#39;s general inventive concept.