| 摘要 |
The method relates to the measurement of fibrous material, such as ribbons and rovings, by means of ultrasound. A suitable arrangement of sound transmitter (3), sound receiver (8) and fibrous material (6) ensures that all the sound waves reaching the sound receiver (8) have permeated the fibrous material (6). By operating the sound transmitter (3) in a pulsed manner and, accordingly, arranging for the sound receiver (8) to be ready to receive for short periods only, all the lagging interference signals generated by reflections and interferences are suppressed, which ensures that the variable to be measured, i.e. the amount of fibres (6) present at any time in the measuring section, is largely free from interference. This measured variable can be utilised as a value for the cross-sectional uniformity or alternatively as a controlled variable for the production of uniform rovings or ribbons. <IMAGE>
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