Multi-Source-CT for inline inspection of extruded profiles

The market for extruded profiles for different applications (automotive, construction sector) is a big part of the plastics processing industry. Currently, the whole production process runs almost without quality checks. Only random tests are done to check the profile for its geometry, dimensions and defects. For extruded pipes and other rotation-symmetric products, there are special inline-inspection systems. However, none of these systems is capable of checking the whole inner and outer geometry of an arbitrarily formed profile. Due to this, we evaluate a concept for a multi-source-CT system, which is able to inspect the whole geometry of extruded profiles during the production process. In this work, we evaluate a concept and build a prototype system to validate the functional capability. Considerable attention is paid to the use of commercially available components because of the cost-effectiveness of the whole system. On the whole, the system comprises 16 x-ray-sources and two polygon-shaped detectors. The components are separated into two rings, each with eight x-ray sources and one detector. The rings are arranged around the extrusion line so that extruded profile traverses through the rings during the extrusion. The whole system is semi-static, which means the components are rigid relative to each other, but the system makes an eccentric movement perpendicular to the direction of extrusion. Due to this, the number of projection angles increases from 16 to about 420 projection angles, which is sufficient for reconstruction. To further increase the sampling rate, three x-ray-sources are pulsed simultaneously. Therefore, we are able to do a full 3D scan of extruded profiles with an extrusion feed of up 100 mm/sec.