| 摘要 |
<p>747,285. Feeding webs. POWERS CHEMCO, Inc. Feb. 15, 1954 [May 14, 1953], No. 4417/54. Class 100 (1). A web feed mechanism includes a hollow perforated roller over which web material is passed, means for maintaining the web material in contact with the hollow perforated roller by suction applied through the apertures, and means for reducing or substantially eliminating suction through those apertures not covered by the material. As shown, a hollow, cylindrical feed roller 10, Fig. 1, has a shell 11 provided with apertures 12 arranged in groups, such that a web 40 passing around the roller 10 is caused to adhere to the roller 10 by suction. The apertures are preferably arranged in groups of four apertures, in which case each group communicates with a chamber 16, Fig. 4, formed by recessed strips 14 attached to the inner surface of the shell. Each chamber 16 has a passage 18 leading to the interior of the roller which communicates with a source of suction. The passage 18 is closed by a reed 20, such as a metallic leaf spring, when the corresponding apertures 12 are uncovered by reason of the large initial flow of air through the passage 18. A bleed hole 22 in the reed 20 permits a very restricted flow of air into the roller, causing the reed 20 to spring away from the passage 18 when the corresponding aperture 12 becomes covered by the web. Alternatively, the bleed hole 22 may be replaced by grooves in the seating surface of the reed 20 or the strip 14 to provide bleed passageways.</p> |
