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all scribe-sheets, peelcoated films and general negative are punched
before the contact process. The devised punching machine pro
duces four oblong holes in the margins of the sheets, depending on
the sheet size.
Fig. i. The punching machine consists of: i. a solid steel base-plate
940x800x25 mm; 2. a solid steel upper plate, 904x800x15 mm;
3. 4 cylinders of a pneumatic system; 4. iron studs to ensure good
positioning of the sheets to be punched; 5. knobs to push down the
punches, 6. holes in base plate just beneath the punches; 7. register
studs to ensure good position of upper plate on case plate; 8. tube
for air of 2J atm.9. the cock of the pneumatic system.
To have a sheet punched one firstly has to open the cock so that
press-air (2J atm.) can enter the cylinders. The air-pressure causes
that the plungers in the cylinders move upwards and lift up the
upper plate. The air enters the apparatus through a central pneu
matic system and from the central air-room the four cylinders
receive the pressure through four conduit pipes. This ensures
simultaneous raising of the four plungers.
Secondly one puts the sensitive polyester sheet in the apparatus
e.g. one places the sheet on the base plate with two edges against
little register pins, screwed in the base plate.
Thirdly one closes the cock in the air-conduit and by the weight
of the upper plate the plungers go down and the upper plate tends
to reach the base plate.
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