| 摘要 |
A shower of fibrous material is directed against the underside of the lower reach of a foraminous endless belt conveyor so that the fibrous material gathers into a continuous stream which is attracted to the conveyor by suction and is moved longitudinally past a trimming device which removes the surplus. The density of the stream is monitored upstream and downstream of the trimming device, and the corresponding signals are processed in an evaluating circuit into additional signals which are indicative of the quantity of the removed surplus. The removed surplus is weighed and the weighing device generates signals also denoting the quantity of the surplus. Such signals are compared with the additional signals and further signals, which denote the differences between the intensities of the compared signals, are used to modify signals denoting the density of the stream downstream of the trimming device. The thus modified signals are used to adjust the trimming device. This ensures that, if the density monitoring operation is carried out by detectors employing sources of infrared light, signals which are generated by such detectors are not affected by certain variable parameters of the fibrous material, such as by the color of tobacco shreds. |
