Patent GB-1206959-A (GB)
Title: Fluidic control for leak detection system
IPC: A24C5/34
Filed: 1967-12-12
Abstract: 1,206,959. Testing cigarettes. CORNING GLASS WORKS. 12 Dec., 1967 [13 Dec., 1966], No. 56303/67. Heading A2C. Empty or filled hollow articles, such as cigarettes, are inspected for leaks by a system comprising: sensing means for deriving a fluid inspection signal, the amplitude of which is related to the rate to which fluid leaks from an article under test, fluidic control means responsive to the sensing means for generating a fluid rejection pulse when the inspection signal falls below a predetermined threshold level, means for inhibiting the utilisation of the fluid inspection signal by the control means except for a period of time during which an article is being tested, and means for utilising the rejection pulse to reject an excessively leaky article. Cigarette rod inspection. Double length filter-cigarette rods 2 are held on an inspection drum 1, between grooves of annular bands 3, 4, by suction applied through sets of openings 5. A suction source (not shown) is connected to the openings 5 via a pipe 6, a rotatable coupling 7, a manifold 8 and sets of pipes 9, 10, 11, 12, 13. The drum 1 is intermittently rotated and, during successive pauses in its rotation, nozzles 23, 24 are inserted by the action of cams 25, 26 into successive pairs of holes 21, 22 in drum ends 14, 15 to sealingly contact both ends of each cigarette rod 2 in turn as it reaches a testing position near the bottom of the drum 1. Air pressure is then applied to the cigarette rod 2 being tested through nozzles 23, 24, from a pneumatic source (not shown), via pipes 29, 30, 31. A back pressure control signal A is obtained from a pipe 34, and a timing signal B is provided by a slotted disc 35 facing an impacting air jet issuing from a pipe 39. The disc 35 is mounted for rotation with the drum 1, the phase of the timing signal B being preset by an adjustable mount. Alternatively, the timing signal B may be obtained by mounting the pipe 39 adjacent one of the holes 21 or 22 at a location where no cigarette rod 2 is being supported, phase adjustment being effected by moving the pipe 39 relative to the holes on the drum 1. When the monitored back pressure signal A at the pipe 34 falls below a predetermined threshold value, a pneumatic control circuit produces a pneumatic rejection signal G slightly delayed due to the phase of the timing signal B, and this signal G is fed to a pipe 20 that connects through a hole 19 in a stationary disc 18 with the particular suction pipe 9 supplying holding suction to the cigarette rod 2 under test. The pressure of the delayed signal G is sufficient to overcome the suction in the said pipe 9 and create a pressure of about one p.s.i above atmospheric and so eject the faulty cigarette just after the drum 1 begins to rotate again after the testing operation. The pneumatic control circuit comprises a pneumatic trigger 41, NOR gates 44, 45, a load insensitive fluid flip-flop 46, and a power fluid flip-flop 47. The pneumatic trigger 41 consists of a proportional amplifier 42 and a flip-flop 43. The power input nozzles P of the NOR gates 44, 45 and the flip-flop 46 are directly connected, and the amplifier 42 and flip-flops 43, 47 are connected by restrictors 48, 49, 50 respectively, to a pneumatic power source P O . A valve 51 is adjustable to bias the pneumatic trigger 41 to switch at the required threshold rejection level. Output channels 44A, 45B of the NOR gates vent. to atmosphere at points V. As shown in Fig. 5, the control signal A consists of pulses corresponding to successively tested cigarette rods, the one shown in column 3 falling below the acceptable level and so designating a leaky rod. The timing signal B can be regarded as a positive signal interrupted by negative pulses. The resultant wave forms produced at the bracketed points C, D, E, F in Fig. 4 are also shown. The output G of the final power flip-flop 47 contains a positive output pulse for each defective cigarette rod sensed, see column 3, delayed to start in phase with the timing signal B and lasting until the start of the next timing signal that also corresponds to an acceptable cigarette rod.