Infrared system inspects coils

Infrared system inspects coils

Today`s PC-based hardware and software are allowing systems integrators to rapidly configure machine-vision systems and reduce development costs. One developer, Concepts In Computing (Beloit, WI), recently used an off-the-shelf camera, a frame grabber, software, and programmable logic controllers (PLCs) to build a system to automatically inspect coils.

According to Jim Saudargas, company president, the vision system was needed to test whether wire leads from the coil were properly bonded to external connecting legs and whether the welds were good, open, or partially bonded. Because the welds are coated, visible-light techniques could not be used to perform the task. But by applying power to the coils, temperature measurements and bond profiles could be made using infrared (IR) techniques.

To do these tests, Saudargas coupled a DT3155 PCI frame grabber from Data Translation (Marlboro, MA) with a Model 760 IR camera from Inframetrics (Billerica, MA). "The system needed to grab 30 frames per second and calculate the joint`s temperature change over a specific time frame," Saudargas says. "Variations in temperature then allowed welds to be classified," he adds.

To inspect every weld joint of the coils, Saudargas developed a Windows-based program using HLImage++--a general-purpose, advanced image-processing software package from Western Vision (Salt Lake City, UT). And, because the system was required to operate on a production line, an automatic set-up procedure was incorporated into the system.

System operation

In operation, a Pentium 166 computer running Microsoft Windows NT displays the camera image continuously in a window centered on the display screen. At the end of each test, the results are displayed in a box below the image with a count of good and bad parts. The complete process is controlled by programmable logic controllers from Allen Bradley (Milwaukee, WI); the controllers signal the computer when to begin the test and, after the test is complete, where the coil is directed on the production line.

HLImage++ was chosen for the application because of its object-oriented programming library application interface. It can be used with Microsoft C++ to produce custom tools and applications. Using HLImage++ with the DT3155, Saudargas could define significant areas of interest before developing any application code. Using HLImage`s ImageObject, ROI Object, and the DT3155 Picture Object, bonded areas could be determined automatically and displayed using an overlay. This method allows a set-up person to see where the joints should be. If necessary, a dialog box can then be invoked, allowing the settings to be modified.

For information, contact Jim Saudargas at [email protected]; for more on the DT3155 and HLImage++, contact Data Translation at (800) 525-8528.