Non-Contact Measurement of Plastic Extrusions
Ongoing measurements enable immediate product correction
The challenge was to continually capture the precise circumference measurements around a complex, 6in (152 mm) diameter extrusion as it exits a die. Once measured, the system needed to process the measurements immediately to feed back to the extrusion system so that a more consistent product would be generated.
Newton engineers developed a compact unit containing a ring of structured light consisting of four laser line generators and four cameras. The optical hardware is built into a custom, waterproof and self-cleaning enclosure. The cameras track the freshly produced extrusion and modify the coordinate system of the measurements to produce accurate results, regardless of the natural wander of the extruded material on the x-y axis. Each of the four area scan imagers capture an image of the laser stripe on the extrusion at a sampling rate of 30 times per second.
The vision system inspects 360 degrees around the extrusion and extracts measurements that are constantly fed back into the adjacent extrusion machine. The developed vision system is adaptable and trainable to accommodate extrusions that vary in diameter, profile shape, contour and color.