machinery feature | 2016 – Downstream equipment


NDC’s AccuScan 6012 four-axis gauge can measure products up to 12mm


end of the line for fi nal quality control. Directly after the fi rst cooling, the Centerwave 6000 provides precise information about inner and outer diameter, ovality, wall thickness and – in particular – sagging. The millimetre wave technology selected for the measure- ment covers the entire range of plastics, including PE, HDPE, PP, PA6 and PVC. If we assume that a line, where tubes are produced with an outer diameter of 400mm and a wall thickness of 27.5mm, at a line speed of 0.5m/min, the machine operator receives accurate measuring results already after around 10 to 30 minutes. Millimetre wave technology is suitable for the


plastic pipes with diameters above 120mm. The Centerwave 6000 measuring system adapts to


the characteristics of the extruded plastic and does not require calibration by the operator. The technology boosts product quality and ensures signifi cant material and cost saving during extrusion, says Sikora. A number of techniques exist to check the quality of


extruded plastic pipe, including optical and ultrasonic technologies, but these have limitations, says the company. Another technique is to generate terahertz impulses at the pipe: refl ected echoes at the inner and outer boundary layers then determine the wall thicknesses.


Without any information on the properties of the Zumbach’s Profi lemaster


systems form a full cross-sec- tional picture of profi les and pipes


extruded materials or its temperatures, the system measures the outer contour and wall thickness simultaneously, at several positions of the circumfer- ence. Layer thicknesses of multi-layer tubes are also measured precisely. However, the technique cannot yet be used for the measuring the thickness of coatings on cylindrical products. Measurement via millimetre wave technology is based on the FMCW runtime method. Several static or rotating transceiv- ers, arranged around the circum- ference of a tube, continuously send and receive frequency modulated millimetre waves. From the runtime difference, the product dimensions are defi ned. Because product temperature has no infl uence on the result, the system is installed for hot measurement as well as at the cold


44 PIPE & PROFILE EXTRUSION | September 2016


measurement of any kind of plastic tube with a diameter of 120-2,500mm. It can handle either single- or multi-layer tubes. During production, there is a risk that the melt that leaves the tube tool will fl ow under gravity, and negatively affect tube wall thickness distribution. This sagging is picked up by millimetre wave measuring.


In-line control Zumbach will also focus on in-line measurement and control of pipes and hoses. Its Wallmaster ultrasonic system offers application-specifi c solutions for measuring and monitoring eccentricity and wall thickness. It is tailored to measuring and monitoring monolayer synthetic pipes and hoses. The measuring data processor with touch-screen display gathers data and QC automatically. When combined with ultrasonic UMAC scanners,


ODAC diameter measuring gauges and error detectors, the measuring and monitoring scale can be expanded to outside and inside diameter, statistics, SPC and processor communication, says the company. Wallmaster can help manufacturers to cut their


expenditure on raw materials, with a return on investment expected within a few months. Using these systems can also reduce the start-up time. Transducers can be individually or simultaneously


adjusted to the best possible measuring position within seconds. The scanners cover an outside diameter up to 180mm. At the same time, its Profi le-


master systems are an accurate and economical way to measure the dimensions -- including complete cross-sections – of pro- fi les and pipes. All relevant dimensions such as width, height, angle and radii are added together, to form the full cross-sectional picture.


www.pipeandprofile.com


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