Control device of the compactness of a strand of fabric, such as a lock fitting of a cigarette filter to or similar.

摘要

1,128,685. Tobacco smoke filters. MOLINS CO. Ltd. and D. W. MOLINS. 17 April, 1967 [18 April, 1966], No. 16923/66. Heading A2C. [Also in Division G3] A filter tow FT is fed and stretched by pairs of rollers 11, 11 and 12, 12, the pair 12, 12 being driven in synchronism with the feed of a continuous paper wrapper 15 to a wrapped-rod forming mechanism 16 and a cut off 17, while the other pair of rollers, 11, 11 are driven at a slower speed which speed is controlled to vary the degree to which the tow FT is stretched in response to detected variations in the density of the filter tow. The airpermeability of the stretched tow FT is determined by suction produced by a fan 22 and applied via an air flow restrictor 21a and a suction chamber 20 that draws air through a section of the moving tow FT that contacts an air-permeable periphery of a suction drum 18. A Beta radiation source 34 and a detector 33 sense variations in the mass per unit length of the wrapped filter rod FR. Short term variations in the permeability of the tow FT and in the mass per unit length of the rod FR are transmitted, via a transducer 24 and an electrical connection 35a respectively, to a memory unit 25 which rejects cut plug lengths F the density of which fall outside the preset limits. An integrating chamber 27 produces a signal dependent on long term variations in the detected air-permeability of the tow FT which signal, via a known hydraulic amplifier 31, a lever 53 and link 49, and a known variable speed reduction gear 49, adjusts the drive speed of the rollers 11 and hence the degree of stretching of the tow FT in response thereto. Similarly, signals corresponding to long term variations in the Beta radiation detected density of the rod FR, forwarded by an integrating device 36, are used to actuate a reversible electric motor 38 that, via a threaded spindle 39 and a nut 40, and the lever 53 and link 49, also control the drive speed of the rollers 11.