Extrusion International 3-2022

49 Extrusion International 3/2022 Processing In the case of mounting the CiTriS on a lance, which is inserted into the bore, the encoder will be mounted directly on the on the lance guide. 3D-measurement By using this additional infor- mation, software can assemble all cross sections with precise depth information to create a point cloud of the inner surface of the bore. The result is a complete 3D-model of the bore. The complete model can be dimensioned and analysed, with the ability to highlight and dimension defects. For the appli- cation of third party external 3D analysis software, STL-export is available. Picture 3 shows a worn extruder bore with local grooves in colour scaled display. Collinearity and straightness determination The collinearity of the extruder elements describes a misalignment between the individual elements. In order to measure such an off- set, CiTriS is mounted on a roller slide peeping out. At the transi- tion between two elements A and B (Picture 4), the centering should take place in element A and the measurement in element B. By ftting a circle to the mea - sured data of CiTriS, an offset can be calculated. This value changes suddenly as soon as the measur- ing plane of CiTriS has been moved from element A to element B. To determine the straightness of an extruder bore, an additional point laser is radiated through the extruder elements from the oppo- site bore opening as a benchmark. CiTriS will be guided slidable and approximately centrical, e.g.mounted on a roller carriage, into the bore opening. A module consisting of a camera and a focusing screen is attached to the front of the CiTriS to detect the directional laser. The laser beam serves as an abso- lutely straight reference line. The de- tection unit ismoved along this refer- ence line in the pipe. Here, the offset to the reference line is continuously measured by the local detection of the laser point on the screen. A possible displacement of the de- tection unit from the center of the bore hole can be corrected using the measurement values from CiTriS. (Picture 5) The result provides the offset of the center point of the respective bore cross-section to the reference line at each measurement position. This corresponds to the straightness of the extruder bore. With this structure, a possible mis- alignment of individual extruder elements in relation to one another becomes visible due to a jump in the coordinates when the roller carriage transits from one extruder element to the next. This corresponds to the collinearity of the extruder elements to each other. Measurement in tubes For tube inspection, 2D analysis software is already available. The In- spectionoutput are radii, ovality, min- imum internal diameter, maximum internal diameter and tolerances. Us- ing an external measurement stand, or a centraliser inserted into the tube, the analysis is possible over the total length of the tube. For 3D inspection of the tube end a special scanner is available which moves the sensor up to 300 mm into the tube and inspects the tube end completely from the in- side (see picture 6). Tube diameter, ovality and dents will be measured. A special feature is the measurement of the pipe end cut geometry and the weld seam profle (cut geometry is important for tubes that will be weld- ed together). For the complete scan of tubes, a crawler with integrated CiTriS is available (see picture 7). The crawler propelled scanner moves through the complete tube and checks the inner surface for defects. Additional features for tube straightness are available. The standard CiTriS sensors have a diameter of 55.9mmand radial mea- surement ranges of 50 mm to 500 mm. The sensor has aUSB-3-interface for 5V-power supply and data inter- face to a computer. The laser class 2M allows applications without any special safety measures. For develop- ers, who would like to integrate the sensor into their own applications, an Application Programming Inter- face (API) is available. GL Messtechnik GmbH Industriestr. 3-5, 55595 Hargesheim, Germany www.gl-messtechnik.de Picture 4: Measurement of the offset from element A to element B with CiTriS Picture 5: Straigtness measurement Picture 6: 3D Crawler Picture 7: 3D Tube inspector