Patent GB-885858-A (GB)
Title: Machine for applying leaves to bases
IPC: H01J9/06
Filed: 1959-06-17
Abstract: 885,858. Coating surfaces with pre-formed sheets. SYLVANIA ELECTRIC PRODUCTS Inc. June 17, 1959 [June 20, 1958], No. 20857/59. Class 93 [Also in Group XXX] A machine for coating a cathode base with a leaf of electron-emissive material having a soluble binder therein comprises means for wetting the base with a solvent for the binder, means for bringing the wetted base and the leaf initially in juxtaposition to each other but out of contact, and further means for bringing the base and leaf into contact along a line of contact from which the leaf can subsequently be caused to wrap around the base. The electron-emissive cathode material may comprise mixed barium, strontium and calcium carbonates in a nitrocellulose binder, the solvent may be a mixture of amyl acetates, and the base may be a hollow metal sleeve of circular, oval or rectangular crosssection. As shown in Fig. 1, the strip 73 of electron-emissive material is fed from a roll 76 mounted in a bracket on a movable carriage 52 also carrying a shoot 54 having cam-controlled clamping mechanism 72 for intermittently clamping and releasing the strip 73. The carriage 52 is reciprocated by cam mechanism in the longitudinal direction of the shoot 54, the strip 73 being clamped prior to forward movement and released prior to backward movement so that it is fed intermittently forward. Cam-controlled punching mechanism 100 stamps out leaves 101, Fig. 9, from the strip 73. The shoot is provided with a slot 107 under which the die 106 moves upwardly to contact the strip 73, then the combined stripper pad and clamp 108 clamps the strip against the die, and finally the punch 104 descends to punch out a leaf 101 and deposit it on a plate 179 on an indexible turret 150. When the punch 104 rises, the clamp 108 continues to hold the strip 73 by virtue of the spring connection 124 between the plunger 122 and the support block 114 until the rising block strikes the head 126. The punched-out surplus strip material 73 is conducted over a driven roller 149, Fig. 1, to a waste receptacle. The top of the turret 150, Fig. 2, is provided with eight pairs of depressions 174 between which are slightly raised perforated lands on which are fitted plates 179 provided with two rows of apertures 179A, 179B, Fig. 28. Underneath the top disc of the turret is a valve disc which has portions ensuring that at positions A and B, Fig. 2, suction is applied to the apertures 179A, 179B, while at position C an air blast is applied. The sleeves 205, Fig. 17, which are oval in crosssection, are fed from a hopper 210 (see also Fig. 1) down which they slide to a delivery slot of thickness slightly greater than the minor axis of the sleeve oval. A vibrating tapper 215, Fig. 1, is provided to assist downward movement of the sleeves. Beneath the hopper is a camcontrolled reciprocating slide 216 provided with a slot 218 deep enough to receive a sleeve with major cross-sectional axis vertical and wide enough to accommodate a sleeve with major axis horizontal. As the slide 216 moves to the right in Fig. 17, the lug 220 flexes the leaf spring 222 to move the gate bar 224 to release a sleeve 205 to the top of the slide, and on the return movement of the slide 216 the sleeve falls into the slot 218. A dog 228 pressed down by a spring 232 rides in the shallower cross-slot 226 and engages the sleeve to rotate it to the position with the major axis horizontal, the sleeve being held in this position by suction applied through the passageway 234 and port 236. After the sleeve passes the dog 228, the slide is retracted to the 2nd position shown, and is again advanced to the 3rd position so that the dog acts on the sleeve for the second time. At the 3rd position, the sleeve is picked up by fingers 260, Fig. 1, and 261 on a rotatable and verticallyreciprocatable turret 262, the finger 260 being fixed and the finger 261 being pivoted and spring-urged towards finger 260. With some forms of sleeves, holding recesses may be provided near the ends of the fingers. As shown in Fig 2, at station L the fingers are opened by engagement of the roller 308 on finger 261 with cam-controlled lever 310, and pick up a sleeve 205 from slide 216. The fingers close, pass to an idle station M, and then to a station N where the lowered sleeve contacts a felt pad over which a stream of solvent is pumped. At station O, the sleeve is vertically aligned with a leaf on the plate 179 at station C of the lower turret, air being blown through nozzle 338 to distribute the solvent along the sleeve. -As shown in Fig. 28, air blown through perforations 179A, 179B blows the leaf 101 up into contact with the underside of the sleeve 205, and the action of the solvent causes the leaf to wrap round the sleeve. At stations P to T, the sleeves are partially dried by hot air from an arcuate tuyere 340. After passage through the idling station U, the coated sleeves are removed at station V, the following station W being another idling station. At station V, the fingers are opened by co-operation of the roller 308 with a cam-controlled lever 362, and the sleeves drop into buckets 344, Fig. 33, having arcuate bottoms to prevent contact of the sleeve coatings with the buckets and mounted on right-angle pieces 346 shaped to form chain links of a conveyer. The chain passes over an idler sprocket 350 and a driving sprocket supported in an extensible frame 354 for tightening the chain. The shaft 360 of the driven sprocket carries a ratchet wheel 370 engaged by a pawl 372 on an arm 374 connected by a link 376 to a cam-operated lever. The conveyer is enclosed by a heat shield 390 containing infra-red lamps 392, and the sleeves finally drop into a tray 394. Specifications 639,048 and 787,926 are referred to.