| 摘要 |
A method of and apparatus for uniformly debossing and perforating a ribbon of thermoplastic sheet material or film through the use of vacuum in combination with a flash heating source such as a flow of hot air. The apparatus causes a ribbon of such film to be forwarded from a supply such as a roll of thermoplastic material, then about a circumferentially extending portion of a rotating debossing-perforating cylinder, and then downstream where the debossed and perforated film may be further processed or where it may be wound on a spool to form a roll thereof. The debossing-perforating cylinder comprises a perforated tubular member through which a plurality of independently adjustable levels of vacuum can be applied from within the cylinder to circumferentially spaced sections of the film in contact with the exterior surface of the perforated tubular member. The apparatus further causes a virtual curtain of hot air to be directed radially inwardly towards a predetermined zone of the perforated tubular member. Then vacuum applied from within the cylinder acts in concert with the curtain of hot air which flash heats the film sufficiently to effect debossing and perforating the film running circumferentially about the rotating cylinder. The apparatus may further control tension in the film both upstream and downstream of the debossing cylinder at predetermined constant levels. A method of making the perforated tubular member is also disclosed which entails forming the member inside-out, and then turning it right-side-out by slitting it longitudinally, reverse rolling it into the desired tubular shape, and then seaming it along the slitting formed edges. The tubular member can then be coated with a release enhancing material such as Teflon (registered trademark, E. I. DuPont Co.) on its radially outwardly facing surface to facilitate releasing the thermoplastic film after the film has been debossed and perforated thereon.
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