| 摘要 |
<p>Inside the drum and towards the exit end are helical rails which are shaped and aligned so they drive the castings towards the drum outlet; and gaps are provided between the rails and the inner wall of the drum so the sand can travel through the gaps. The rails are pref. made from round bars or tubes, and the radial gap for the sand pref. increases in size towards the exit end of the drum. The rails are pref. bent in a curve travelling inwards and then bent so the rails have a sawtooth profile. The pref. drum has a tapering cone at its outlet end, followed by a perforated section, the sand falling through the perforations. The path taken by both the castings and the sand is sufficiently long to ensure that both are adequately cooled before leaving the drum.</p> |
