Posi-Draw Vacuum Roll

The Dusenbery Posi-Draw vacuum roll system evolved out of the need to make high precision coatings on very thin plastic substrates and to transport these webs with minimal damage. Vacuum rolls offered by other suppliers, although allowing the elimination of nipped roll transport, did not provide the fine tension control and flaw-free handling needed for the thinnest and most fragile webs. In slitting, the problems of tension control and protection of fragile coatings on very thin webs was just as severe.

An entirely new approach to vacuum roll design and construction was envisioned. A roll surface of continuity and smoothness solves problems related to dimple marking of thin plastic webs. A controlled use of vacuum force, in the web wrap zone only, provides energy efficiency in addition to fine control of web tension. A separate zone of positive pressure following the vacuum zone is now possible. Clinging of the web to the roll is totally eliminated while continuously purging contaminants from the roll surface.

PRODUCT DESCRIPTION The Dusenbery Posi-Draw roll is constructed of a solid metal cylinder grooved with air channels which are covered by sintered stainless steel bars of controlled porosity. Although the circumferential surface of the roll is of alternating solid metal and sintered stainless bars, precision finishing allows it to act as a smooth, continuous surface.

Stationary structures at each end of the roll containing internal cavities are strategically provided to access the channels located beneath the sintered bars. The roll rotates against a friction bearing seal. Two cavities; exhaust (vacuum) and pressurized air, relating to web wrap position and departure point control the web on the roll surface. Virtually any degree of wrap and web position can be accommodated by the design.

For more information, contact: rmccarthy@parkinsontechnologies.com