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Case Studies

Assembly of Parking Distance Sensors Using Robots

Stäubli Robotics

A high-precision task

The production of around 200,000 parking distance sensors daily represents an exceptional challenge for automation. In particular, assembly of the contact pins and associated integrated quality control requires the utmost precision whilst maintaining high-speed duty cycles.

At prestigious systems manufacturer Kutzschbach Electronic, the decision was made to go for a rotary machine in this instance, with the aim of satisfying the twin criteria of small footprint and high output. There are currently almost twenty Kutzschbach installations producing around a dozen different versions of the sensor on machines that are almost identical in layout at production sites in Germany, in Europe and around the world.

Assembly always follows the same sequence. A linear unit takes care of feeding and positioning the piezo sensor housing on the rotary plate. At the first station, a simple quality check is carried out in which the piezo element is subjected to measurement of its electrical resistance and capacitance.
Robots: Precision and high speed in demand

Walter Wüst, Head of Software Development at Kutzschbach, summarizes why the choice came down to a Stäubli TX60: “The TX60 meets our requirements to perfection. However, the unique feature of this Stäubli robot is its incredible accuracy and repeatability, characteristics that a standard robot can barely attain and which are crucial for this application.”

The TX60 takes one of two contact pins directly from an associated punching station; picking up the pins with the delicate miniature grippers is an extremely difficult process in itself. Maximum precision is then required in inserting the contact pin into the sensor housing. In the thin-walled injection molding sits a guide that is barely visible to the naked eye, in which the six-axis robot positions the pin securely, quickly and accurately. To complete assembly, the Stäubli machine then picks the second pin and repeats the process.

After successful installation by the robot, the rotary table revolves round to a hydraulic power unit where the pins are pressed into their final position, an operation that the robot itself cannot perform with its refined miniature grippers due to the force required. The final step in the rotary indexing plant consists of connecting the pins by means of laser soldering. After one last quality check, the sensor housings with their pins now connected are ejected and continue via the transfer system to further stages in the manufacturing process.

“The fact that we have already built nearly twenty such plants for our customers emphasizes the productivity and profitability of this automated solution,” says Roland Schmid, Head of Software Assessment Management at Kutzschbach. “The short cycle times and the required process stability in the intricate assembly task would certainly not be possible without the Stäubli robots.” 
Automated Imaging Association Motion Control Association