| 摘要 |
1308356 Duct H TRUTZSCHLER and H TRUTZSCHLER 2 Oct 1970 [3 Oct 1969] 47018/70 Heading F2P [Also in Division D1] A flock depositing duct has a wall portion provided with apertures for outflow of the conveying gas and its inner surface in the region of the apertures provided with a plastics coating having a coefficient of friction relative to the flock which is substantially smaller than that of a sheet metal surface lacquered in a way that is usual for flock depositing ducts. The perforations are preferably rounded at their edges exposed to the plastics surface and the preferred plastics is polytetrafluorethylene. |
