Portable acoustic apparatus for in-situ monitoring of a weld in a workpiece

An apparatus for in-situ monitoring of a welded joint in a workpiece includes an ultrasonic sending transducer and a receiving transducer. The ultrasonic sending transducer includes a probe head disposed on a plurality of individually-activatable piezoelectric elements, and a plurality of waveguide probes projecting orthogonally from a planar surface. A wave attenuator is disposed between individual ones of the waveguide probes. A receiving transducer is disposed therein. The workpiece is insertable between the waveguide probes of the ultrasonic sending transducer and the receiving transducer. The ultrasonic sending transducer urges the probe head towards the receiving transducer such that the waveguide probes physically contact the welded joint in the workpiece. The piezoelectric elements individually excite the waveguide probe that is in physical contact with the welded joint in the workpiece. The acoustic receiving transducer is disposed to monitor the welded joint in the workpiece.

INTRODUCTION

Evaluation devices and methods may employ ultrasonic or other acoustic signals.

SUMMARY

An apparatus for in-situ monitoring of a welded joint in a workpiece is described, and includes an ultrasonic sending transducer and a receiving transducer. The ultrasonic sending transducer includes a probe head disposed on a plurality of individually-activatable piezoelectric elements. The probe head includes a plurality of waveguide probes projecting orthogonally from a planar surface thereof. A wave attenuator is disposed between individual ones of the waveguide probes. A receiving transducer is disposed therein. The workpiece is insertable between the waveguide probes of the ultrasonic sending transducer and the receiving transducer. The ultrasonic sending transducer is disposed to urge the probe head towards the receiving transducer such that at least one of the waveguide probes physically contacts the welded joint in the workpiece. The piezoelectric elements are controllable to individually excite the at least one waveguide probe that is in physical contact with the welded joint in the workpiece. The acoustic receiving transducer is disposed to monitor the welded joint in the workpiece.

An aspect of the disclosure includes the ultrasonic sending transducer being disposed to urge the probe head towards the receiving transducer such that at least one of the waveguide probes is in physical contact with a bonding area of the welded joint in the workpiece.

Another aspect of the disclosure includes a controller in communication with the individually-activatable piezoelectric elements of the ultrasonic sending transducer and the acoustic receiving transducer, wherein the controller is disposed to command operation of at least one of the individually-activatable piezoelectric elements that is associated with one of the waveguide probes of the ultrasonic sending transducer, and the controller is disposed to monitor the acoustic receiving transducer.

Another aspect of the disclosure includes the plurality of individually-activatable piezoelectric elements being disposed in a rectilinear grid array, wherein each of the piezoelectric elements is associated with only one of the waveguide probes.

Another aspect of the disclosure includes each of the waveguide probes including a tip portion that is configured to be conformable to a bonding area of the welded joint in the workpiece, wherein a dry couplant is attached to the tip portion.

Another aspect of the disclosure includes the dry couplant attached to the tip portion being a polymer.

Another aspect of the disclosure includes the weld joint of the workpiece including a plurality of weld troughs arranged in a pre-defined topography, wherein the plurality of waveguide probes are disposed on the probe head in correspondence to the plurality of weld troughs of the pre-defined topography.

Another aspect of the disclosure includes the acoustic receiving transducer being an acoustography film.

Another aspect of the disclosure includes the acoustic receiving transducer being a multi-element acoustic receiving transducer arranged in a rectilinear array.

Another aspect of the disclosure includes the acoustic receiving transducer being a flat surface.

Another aspect of the disclosure includes the probe head being disposed on the ultrasonic sending transducer including a first configuration of waveguide probes projecting orthogonally from the surface thereof, and the probe head being replaceable with a second probe head having a second configuration of the waveguide probes projecting orthogonally from the surface thereof, wherein the first configuration of waveguide probes has an arrangement that differs from the second configuration of waveguide probes.

Another aspect of the disclosure includes the first configuration of waveguide probes including a plurality of waveguide probes, and the second configuration of waveguide probes including a single waveguide probe.

Another aspect of the disclosure includes the apparatus for in-situ monitoring of a welded joint in a workpiece being operable to provide in-situ non-destructive testing and examination of a welded joint in a workpiece absent immersion in a fluidic bath or application of a gel/fluid couplant.

DETAILED DESCRIPTION

The components of the disclosed embodiments, as described and illustrated herein, may be arranged and designed in a variety of different configurations. Thus, the following detailed description is not intended to limit the scope of the disclosure, as claimed, but is merely representative of possible embodiments thereof. In addition, while numerous specific details are set forth in the following description in order to provide a thorough understanding of the embodiments disclosed herein, some embodiments can be practiced without some of these details. Moreover, for the purpose of clarity, certain technical material that is known in the related art has not been described in detail in order to avoid unnecessarily obscuring the disclosure. Furthermore, the drawings are in simplified form and are not to precise scale. For purposes of convenience and clarity only, directional terms such as top, bottom, left, right, up, over, above, below, beneath, rear, and front, may be used with respect to the drawings. These and similar directional terms are not to be construed to limit the scope of the disclosure. Furthermore, the disclosure as illustrated and described herein may be practiced in the absence of an element that is not specifically disclosed herein.

Referring now to the drawings, which are provided for the purpose of illustrating certain exemplary embodiments only and not for the purpose of limiting the same,FIGS. 1, 2, 3, 4 and 5schematically illustrate various elements, perspectives and details of a monitoring apparatus15that is configured to provide in-situ non-destructive testing and examination of a welded joint93in a workpiece90, wherein the monitoring apparatus includes an ultrasonic sending transducer20and an acoustic receiving transducer40that are operated by a controller10. Like numerals indicate like elements in the various illustrations. The welded joint93of the workpiece90is shown as a lap joint that is effected by ultrasonic welding, but the concepts described herein may be applied to other welded joints that are achieved by other welding processes, such as spot welds or bonding. In one embodiment and as shown, the welded joint93of the workpiece90is interposed between the ultrasonic sending transducer20and the acoustic receiving transducer40to effect the in-situ monitoring of the welded joint93. This can be accomplished by moving the workpiece90into a suitable position between the ultrasonic sending transducer20and the acoustic receiving transducer40, or by moving the ultrasonic sending transducer20and the acoustic receiving transducer40into a suitable position around the workpiece90, depending upon the specific configuration. The monitoring apparatus15including the ultrasonic sending transducer20and the acoustic receiving transducer40can be advantageously deployed in a manufacturing setting for in-line weld quality inspection in a production line. The monitoring apparatus15including the ultrasonic sending transducer20and the acoustic receiving transducer40is operable to provide in-situ non-destructive testing and examination of a welded joint93in a workpiece90absent immersion of the apparatus in a fluidic bath or application of a gel/fluid couplant.

In one embodiment and as shown the welded lap joint93of the workpiece90is formed between a first element91and a second element92, wherein the first element91is lapped with the second element92and welded together employing a vibrational welding tool. The first element91and the second element92may be fabricated from suitable composite polymer materials or metal alloys. The process of vibrational welding can generate the welded joint93that includes one or a plurality of bonding areas in the form of weld troughs94that are caused by a combination of compressive load and vibration that are applied by a sonotrode tip (not shown) to the workpiece90during vibrational welding. Other welding processes can result in other forms of bonding areas associated with a welded joint, which can be subjected to in-situ non-destructive testing and examination employing an embodiment of the monitoring apparatus15described herein.

The ultrasonic sending transducer20includes a probe head30that is disposed on a plurality of individually-activatable piezoelectric elements22. The probe head30can include a single waveguide probe (shown as element632inFIG. 6) or a plurality of waveguide probes32that project orthogonally from a planar surface of the probe head30. The probe head30is preferably fabricated as a unitary device having a base portion and a plurality of waveguide probes32, as shown. The probe head30can be fabricated using three-dimensional printing, machining or another suitable fabrication method and process. The ultrasonic sending transducer20is preferably configured so that the probe head30is replaceable and interchangeable with various probe head configurations, such as the probe head630that is shown with reference toFIG. 6. Details of the configuration and design for a probe head are selected based upon the specific geometry and arrangement of the welded joint of the workpiece, such as the illustrated probe head30having waveguide probes32that correspond to the weld troughs94of the welded joint93of the workpiece90shown with reference toFIG. 1. In one embodiment, the welded joint93of the workpiece90includes a plurality of weld troughs94that are arranged in a pre-defined topography, e.g., a rectilinear arrangement, and the waveguide probes32are arranged on the probe head30to conform to the pre-defined topography of the plurality of weld troughs94.

Each of the waveguide probes32includes a tip portion34that is configured to be conformable to the weld trough94of the welded joint93in the workpiece90, and a dry couplant36can be attached to the tip portion34such that the dry couplant36is interposed between the tip portion of the waveguide probe32and the weld trough94of the welded joint93during operation. Examples of a dry couplant36include a silicone insert, plastic sheeting, cellophane, a rubberize insert, a polymeric insert, etc. The dry couplant36is employed to facilitate vibrational coupling between the waveguide probe32and the weld trough94. This arrangement eliminates any need for immersing the workpiece90into a liquid to effect the measurement.

A wave attenuator38(shown with reference toFIG. 5) can be interposed between the individual waveguide probes32of the probe head30. The wave attenuator38includes, in one embodiment, a plurality of interlocked elements having corrugated surfaces that are arranged in a rectilinear fashion and interposed between individual ones of the waveguide probes32. The wave attenuator38absorbs vibration energy that may propagate from an activated one of the waveguide probes32across the probe head30. The wave attenuator38vibrationally decouples the individual waveguide probes32when the probe head30with a plurality of waveguide probes32is fabricated as a unitary device. The vibrational decoupling of the wave attenuator38avoids or minimizes unintended wave modes and cross-talk between adjacent waveguides32on the probe head30during operation of the monitoring apparatus15.

The plurality of individually-activatable piezoelectric elements22are preferably arranged in a rectilinear grid, e.g., as shown with reference toFIG. 2. Each of the piezoelectric elements22is in communication with the controller10via communication link14. The controller10includes a control routine12that is executable to command and control individual activation and deactivation of each of the piezoelectric elements22. By way of a non-limiting example, the view of the piezoelectric elements22that is shown with reference toFIG. 2includes nine of the piezoelectric elements, which are shaded and identified by numeral24, indicating that they are selectively activatable, as described hereinbelow.

Continuing to refer toFIG. 2, the nine selectively activated piezoelectric elements24are physically adjacent to and in vibrational communication with one of the waveguide probes, which is indicated by numeral33. In operation, vibration energy that is generated by activation of the piezoelectric elements24is transmitted only to the waveguide probe33of the probe head30. No vibration energy is directly transmitted to the other waveguide probes32of the probe head30via the non-activated piezoelectric elements22. As such, the piezoelectric elements22that are activated are those that align with an appropriate feature of the specific embodiment of the probe head30, for example, only the piezoelectric elements24that are positioned over the selected waveguide probe33will be activated in one case. As such, the piezoelectric elements22can be controlled to individually excite one or a plurality of waveguide probes32that is in physical contact with a weld trough94that is a portion of the welded joint93in the workpiece90. Some of the piezoelectric elements22may not be associated with any of the waveguide probes32. For example, there can be unused elements. Furthermore, more than one of the piezoelectric elements22can be assigned to and in vibrational communication with the same one of the waveguide probes32.

The ultrasonic sending transducer20can be disposed in a device (not shown) that includes one or a plurality of elements that exert a compressive load21to urge the probe head30towards the acoustic receiving transducer40such that at least one of the waveguide probes32physically contacts and preferably applies a compressive load onto the welded joint93in the workpiece90.

The acoustic receiving transducer40can be an acoustography sensing system that includes acoustography film, camera, light source, etc. in one embodiment. The acoustography sensing system includes a film that reacts to ultrasound, thus enabling capture of acoustic scan signals without scanning. Alternatively, the acoustic receiving transducer40may be a scanning type application, such as a rectilinear array that is subjected to a phased array scan, an amplitude/time scan, or a paint brush-type scan device. Preferably the acoustic receiving transducer40is disposed as a flat surface.

The controller10is in communication with the individually-activatable piezoelectric elements22of the ultrasonic sending transducer20and with the acoustic receiving transducer40. In operation, the controller10can command operation of the ultrasonic sending transducer20to apply compressive force21to a sample workpiece90. This permits each of the waveguide probes32to have intimate contact with one of the weld troughs94of the welded joint93, affording a precise measurement that is focused only on the area of interest, i.e., the weld trough94.

The controller10can command operation of at least one of the individually-activatable piezoelectric elements22that is associated with one of the waveguide probes32of the ultrasonic sending transducer20, with such operation being in the form of a voltage or force amplitude-time scan (A scan). The controller10further monitors signal outputs from the acoustic receiving transducer40, which are subject to signal processing to evaluate one or a plurality of the weld troughs94of the welded joint93. This operation can execute to step through and sequentially activate the piezoelectric elements22and monitor the output with the acoustic receiving transducer40, in one embodiment. Alternatively, this operation can execute to step through and sequentially activate subsets of the piezoelectric elements22and monitor the output with the acoustic receiving transducer40. Alternatively, this operation can execute to simultaneously activate the piezoelectric elements22and monitor the output with the acoustic receiving transducer40. Such operations can be reduced to algorithmic code that is executed as the control routine12that preferably stored in an executable in the controller10.

FIG. 6illustrates an ultrasonic sending transducer620including a probe head630having a single waveguide probe632that includes a tip portion634with a dry couplant636attached thereto, which may be designed and employed to monitor a spot weld, a bead weld, a rivet, an ultrasonic weld, or another bonding geometry. As such, the probe head is customizable and reconfigurable.

The term “controller” and related terms such as control module, module, control, control unit, processor and similar terms refer to one or various combinations of Application Specific Integrated Circuit(s) (ASIC), electronic circuit(s), central processing unit(s), e.g., microprocessor(s) and associated non-transitory memory component(s) in the form of memory and storage devices (read only, programmable read only, random access, hard drive, etc.). The non-transitory memory component is capable of storing machine readable instructions in the form of one or more software or firmware programs or routines, combinational logic circuit(s), input/output circuit(s) and devices, signal conditioning and buffer circuitry and other components that can be accessed by one or more processors to provide a described functionality. Input/output circuit(s) and devices include analog/digital converters and related devices that monitor inputs from sensors, with such inputs monitored at a preset sampling frequency or in response to a triggering event. Software, firmware, programs, instructions, control routines, code, algorithms and similar terms mean controller-executable instruction sets including calibrations and look-up tables. Each controller executes control routine(s) to provide desired functions. Routines may be executed at regular intervals, for example each 100 microseconds during ongoing operation. Alternatively, routines may be executed in response to occurrence of a triggering event. Communication between controllers, and communication between controllers, actuators and/or sensors may be accomplished using a direct wired point-to-point link, a networked communication bus link, a wireless link or another suitable communication link, and is indicated by line14. Communication includes exchanging data signals in suitable form, including, for example, electrical signals via a conductive medium, electromagnetic signals via air, optical signals via optical waveguides, and the like. The data signals may include discrete, analog or digitized analog signals representing inputs from sensors, actuator commands, and communication between controllers. The term “signal” refers to a physically discernible indicator that conveys information, and may be a suitable waveform (e.g., electrical, optical, magnetic, mechanical or electromagnetic), such as DC, AC, sinusoidal-wave, triangular-wave, square-wave, vibration, and the like, that is capable of traveling through a medium.