Patent GB-619883-A (GB)
Title: Improvements in or relating to film stock perforating apparatus for cinematograph
IPC: B26F1/00
Filed: 1946-08-12
Abstract: 619,883. Perforating kinematograph films. HARPER, M. Aug. 12, 1946, No. 23869. [Class 31(ii)] Kinematograph filmstock is perforated by holding the film during punching in a gate extending across the film, the gate being provided with a stripper which is slotted longitudinally beyond the punches, a claw feeder operating through such slot in perforations just made by the punches. The film is preferably positioned exactly for effecting further perforations by means of a tapered punch element or elements mounted on the reciprocating punch and which enter perforations already made. As shown in Fig. 2, the flywheel 22 is turned by handle 23, or is electrically driven and rotates shaft 52 which drives friction rollers 48, 49 to draw blank film from the spool 12, perforate it and feed it by sprocket 64 to the takeup spool 13 driven by the flexible shaft 68 and friction drive 69. In Figs. 1 and 3 which show the machine in rear elevation and plan respectively, rotation of the flywheel and shaft 19, which carries a cam 18 bearing against two rollers 20, 21, causes the ram 16 carrying the rollers 20, 21 to reciprocate vertically in the slides 15 and so operates the punch 17. The punch 17 carries five elements, two perforating elements 24, one perforating element 25, and two tapered locating pins 26 which are longer than the perforating elements 24, 25 and enter holes previously punched so as to position the film before the perforating elements punch the next set of holes (see also Fig. 5 for the arrangement of the holes). The shaft 19 drives through skew gears 53, 54 the shaft 52, which through skew gears 51 drives the friction feed rollers 48, 49 which are pressed together by spring 55, the tension being adjustable by knob 57, and which may be separated by manual pressure on the pad 56. The film passes through feed rollers 48, 49 in a loop 50 through the film gate, Fig. 5, comprising a base plate 27 perforated at 29, 30 to receive the punches and at 31 to receive the tapered locating pins, and slotted at 41, 42 to receive the claws of the claw feed mechanism described below. The film is pressed against the side wall 37 by a lateral pressure plate 38 backed by light wire springs 39, and is held down by a stripping plate 40, Fig. 1, similarly perforated and slotted. The film is fed intermittently by the reciprocating claws 71 which are pivoted to a slide 73 and attached at 75 to a crank driven through shaft 72 and bevel gears 78, 77 from the shaft 52. The amount of feed imparted to the film by the claw mechanism is adjustable by 'knob 79 which rotates the member 80 carrying the arm 70 along which the slide 73 reciprccates. The film passes in a loop 65 to the continuously rotated sprccket 64 having presser rollers 66, 67, the sprocket being driven through skew gears 63, 62 from the shaft 52. Underneath the punch is a removable box to'receive the waste, the box being held in posittion by an eccentric clamp on the spindle 35 having a handle 36. The machine is intended for perforation of sensitized sub-standard film with alternating double and single perforations leaving a strip down either side, as described in Specification 508,795, [Group XX], and on which a sound track can be contact printed from 35mm. film; as described in Specification 509,009, [Group XX].