| 摘要 |
<p>A method for producing a plastic lined drum using the drum shell as a mold element. The drum shell which is open at the top and at the bottom is positioned in a frame which engages the outer wall of the shell all around. The shell forms a seal a short distance below the open upper end of the shell sealing off the open bottom end of the shell as a bottom wall. A film of thermoplastic material extending across the open end at the top of the shell and a short distance therebeyond is heated to the stretchable stage to form a seal between a portion of the film extending beyond the open end of the shell and the portion of the frame in sealing engagement with the outer wall of the shell below the upper edge. A mold member is displaced vertically downwardly into the interior of the drum towards the open end at the bottom of the shell for a distance less than the length of the shell, to displace the film by expansion into the interior of the shell. A vacuum is created in the space between the interior of the shell and the expanded film and between the frame member and the portion of the film extending beyond the open upper end. This stretches the film into intimate engagement with the interior walls of the shell and the bottom wall, and about the upper edge of the shell and the adjacent outer wall of the shell to the portion engaged by the frame member and downwardly beyond the open end at the bottom of the shell for a distance corresponding to the shrinkage calculated to take place during cooldown of the stretched film. The entire shell which is continuously lined with the plastic material throughout the interior and about the upper edge portion is then removed from the frame, and the bottom wall of the drum is positioned adjacent the open end at the bottom. The lower chime is formed about the edge of the bottom wall to join the bottom wall to the drum with the bottom of the thermoplastic liner resting thereon.</p> |
