摘要 |
A mold for the interior surfaces of one or more spirals is rotated and heated to a temperature sufficient to melt a weldable plastic such as LLDP or HDP plastic in a predetermined amount deposited thereon. Plastic powder not melted is recovered and redeposited until all the plastic powder is melted. The mold or molds are then actively cooled and the formed spiral is removed. An insulation layer is used to improve heating and cooling efficiency, and to control the areas where plastic is deposited. A cover closes the back of the mold.
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