Patent GB-687865-A (GB)
Title: Improvements in or relating to electronic inspection apparatus
IPC: B07C5/342
Filed: 1950-05-11
Abstract: 687,865. Packeting machines. INTERNATIONAL CELLUCOTTON PRODUCTS CO. May 11, 1950 [June 28, 1949], No. 11768/50. Class 94(i) [Also in Groups XXX and XL(b)] In a machine for manufacturing textile articles, e.g. sanitary napkins, from a continuous web of material, the finished articles are normally assembled for disposal in batches of a predetermined number, which are successively stored in a plurality of compartments. and are normally discharged successively by a cyclically operating electrical control device into a plurality of buckets of a conveyer. A photoelectric inspection apparatus viewing the incoming material operates an electronic control on the occurrence of a colour abnormality to energise a predetermined " memory relay set, which, after a time interval during which the abnormal material passes through the machine and is manufactured into articles, operates electrical rejecting means to discard the batch or batches comprising the abnormal material. Figs. 1a, 1b show a machine for manufacturing sanitary napkins wherein a continuous strip of gauze 2 is drawn by rollers 4. over a table 1 of a pad making machine A, to which a continuous web of wadding (not shown) is transversely fed. A reciprocating cutter unit 5 divides the wadding into pads and deposits them in succession along the centre line of the gauze, which travels on to a rotary cutter C where a knife 7 severs the gauze between the pads, which then travel by a conveyer 8 to a folding machine D where the gauze envelopes are folded over the pads. The complete napkins travel by a conveyer 10 to a stacking machine E, which groups the napkins horizontally into batches of a dozen, accommodated alternatively in one or other of the storage compartments 11, 12. A conveyer passing under the storage compartments comprises a chain of buckets 13, each of which carries a cam trigger 13a operating in passing a switch member 13b, which closes contacts 15 to operate a slave relay 14 energising a solenoid 18 to open the bottom gate 19 of the appropriate compartment and discharge the batch therein to the conveyer. Imperfections in the incoming gauze are colour marked in manufacture, and the moving web is inspected therefor by an inspection unit B comprising a lamp 43 and a high vacuum photocell 22 associated with an amplifier unit 23 (Fig. 3) and a self contained selenium rectifier bias and anode supply unit 25, energised from a 110v. A.C. supply line. The cell anode is positively energised, and its cathode load is capacity coupled to the grid of a variably positively biased normally conductive pentode amplifier 47 whose anode circuit is resistance capacity coupled to the grid of a thyratron 48, normally biased to cut-off, whose anode circuit is connected over lines 56, 57 to sequentially operate four similar memory relay sets 24a,24b, 24c, 24d (Fig. 4). A neon indicator lamp 55 across lines 56, 57 indicates striking of the thyratron. A timing arrangement 70 Figs. 5a, 5b (not shown) comprising a cam shaft 71 driven through a reduction gear 72 from the drive of the napkinmaking machine is synchronised to revolve once during the manufacture of each four batches of a dozen, and operates a plurality of hereinafter specified micro-switches in accordance with a predetermined sequence. Cams 75, 101 operate switches 63, 64, 65, 66 to connect lines 56, 57 to the operating coils of the mechanically locked memory relays 80, 115, 90, 125 of relay sets 24a, 24b, 24c, 24d in a sequence corresponding to the manufacture of e.g. the first, second, third, and fourth batch of napkins. If the incoming gauze is satisfactory, the thyratron remains nonconductive, no relay operates, and manufacture and stacking in batches proceeds normally. On arrival of a colour marked defect in the gauze, at the inspection unit, the photocell is darkened, and the thyratron is triggered. The pulse corresponding to defective material for the first dozen batch is switched by cam 75 and contact 63 to operate memory relay 80, which locks, closes contact 82 to prepare a circuit through the reject relay 85, and opens contact 81 in circuit with the release winding 85 R of relay 85. The thyratron is immediately de-energised by the reduction of its plate voltage below striking level by the shock excited oscillation of the series resonant circuit comprising condenser 58a, resistance 59, and the operating winding of the relay 80. After a time interval corresponding to the manufacture of a dozen batch, the cam shaft 71 reaches the midpoint of its cycle and cam 102 momentarily closes contact 95 to operate and lock the reject relay 85, open contact 86 in the operating circuit of the slave relay 14, and close contact 87 in the circuit of the signal lamp 130. After a brief interval. cam 103 closes contact 88 to energise the release winding of the memory relay 80, which unlocks and opens contact 82 in circuit with the reject relay 85, which remains locked operated. Shortly afterwards the conveyer bucket cam trigger 13a closes contact 15, but the slave relay 14 is disabled by the open contact 86 and the faulty batch remains undischarged in the compartment 11. The next succeeding batch entering the compartment (e.g. the third) ejects the faulty batch to a reject chute 21. Shortly after the cam shaft commences its second cycle, cam 102 closes contact 89 to energise the release winding 85 R of the reject relay 85, thus opening contact 86, closing contact 87, and conditioning the apparatus for the next cycle. Cam 101 similarly switches the pulse corresponding to faulty material for the second batch to operate the relay set 24b comprising the memory relay 115, which locks, operates reject relay 120 and releases while relay 120 locks, disables the operation of the slave relay 14a controlling the solenoid 18a opening gate 19a of compartment 12, and finally unlocks, after which the apparatus is reset. The contacts 64, 110, 109, are successively operated by the cam shaft during its second cycle of rotation. Faulty material for the third or fourth batches respectively disable the operation of gates 19 or 19a over the relay sets 24c, 24d comprising the memory relays 90, 125 and reject relays 85, 120, the cycling being controlled by contacts 65, 94, 89 or 66, 111, 112 operated by the cam shaft in a similar manner to that previously described. An operative overlap between cams 75 and 101 ensures that a defect in the material at the dividing point between successive dozens causes the rejection of both batches. Synchronisation may be tested by comparing a signal lamp 134 illuminated on each closure of contact 95 with a lamp 135 illuminated on accumulation of each dozen batch in the stacking machine. The lamps should light simultaneously at the halfway point of each inspection cycle.