| 摘要 |
Inside (sectored) mold (1), a support is located, pressing the plastic mass against the wall of mold sections (2, 3, 4) following its introduction. Hollow molding (6) is pressed over its entire height and circumference, producing a thicker, more even wall, free of air inclusions. Drum edges and any insertions are completed simultaneously.- DETAILED DESCRIPTION - The plastic is hardened before the support is reduced in volume or circumference for extraction.- An INDEPENDENT CLAIM is also included for corresponding equipment to make the drum.- Preferred features: The stiff support is wound with cooled sheet plastic mass and additives, surrounded by the mold, and air-pressurized internally. Mold and support are heated. Vacuum is connected to the support for its extraction. A slight variant is described, involving composite laminar construction. The molding is compressed uniformly to a wall thickness of 4 mm, preferably 2 mm. The initial roll of cooled sheet includes resin, additives etc. It is rolled onto the support, before cutting and molding as described. The edge is formed by bending away at an angle, or as a bead, at the same time as the molding is produced
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