Continuous plastic porous tube mfr. - pouring thermoplastic granules in heated gap between metal tubes

摘要

A porous plastic tube for filtering and aerating purposes is mfd. by pouring thermoplastic granules into the annular gap between two revolving metal tubes, of which the inner can also be reciprocated axially. A heating zone, surrounded by cooling zones, sinters the granules together to a porous tube. This is a continuous low-cost process for tubes which can be buried without clogging the pores.