Abstract: Filter cartridges may have a core element formed of a non-filtering, self-supporting non-woven mass of indefinite length continuous synthetic polymeric core fibers, and at least one annular filtration zone layer formed of a mass of non-woven indefinite length continuous synthetic polymeric filtration fibers. The non-woven core element is most preferably formed in situ during filter cartridge manufacturing by melt-blowing synthetic polymeric core fiber streams toward a forming mandrel. The non-woven core element is completely solidified prior to the filtration zone fibers being melt-blown thereon so that the core and filtration fibers are predominantly mechanically interlocked with one another, instead of being melt-bonded thereto. Filter cartridges of predetermined length may be cut from an upstream filter cartridge preform of indefinite length by subjecting the preform to forced cooling air to thereby minimize (if not eliminate entirely) significant filter cartridge shrinkage over time.

Abstract: Filter cartridges may have a core element formed of a non-filtering, self-supporting non-woven mass of indefinite length continuous synthetic polymeric core fibers, and at least one annular filtration zone layer formed of a mass of non-woven indefinite length continuous synthetic polymeric filtration fibers. The non-woven core element is most preferably formed in situ during filter cartridge manufacturing by melt-blowing synthetic polymeric core fiber streams toward a forming mandrel. The non-woven core element is completely solidified prior to the filtration zone fibers being melt-blown thereon so that the core and filtration fibers are predominantly mechanically interlocked with one another, instead of being melt-bonded thereto. Filter cartridges of predetermined length may be cut from an upstream filter cartridge preform of indefinite length by subjecting the preform to forced cooling air to thereby minimize (if not eliminate entirely) significant filter cartridge shrinkage over time.

Abstract: Filter cartridges may have a core element formed of a non-filtering, self-supporting non-woven mass of indefinite length continuous synthetic polymeric core fibers, and at least one annular filtration zone layer formed of a mass of non-woven indefinite length continuous synthetic polymeric filtration fibers. The non-woven core element is most preferably formed in situ during filter cartridge manufacturing by melt-blowing synthetic polymeric core fiber streams toward a forming mandrel. The non-woven core element is completely solidified prior to the filtration zone fibers being melt-blown thereon so that the core and filtration fibers are predominantly mechanically interlocked with one another, instead of being melt-bonded thereto. Filter cartridges of predetermined length may be cut from an upstream filter cartridge preform of indefinite length by subjecting the preform to forced cooling air to thereby minimize (if not eliminate entirely) significant filter cartridge shrinkage over time.

Abstract: Filter cartridges may have a core element formed of a non-filtering, self-supporting non-woven mass of indefinite length continuous synthetic polymeric core fibers, and at least one annular filtration zone layer formed of a mass of non-woven indefinite length continuous synthetic polymeric filtration fibers. The non-woven core element is most preferably formed in situ during filter cartridge manufacturing by melt-blowing synthetic polymeric core fiber streams toward a forming mandrel. The non-woven core element is completely solidified prior to the filtration zone fibers being melt-blown thereon so that the core and filtration fibers are predominantly mechanically interlocked with one another, instead of being melt-bonded thereto. Filter cartridges of predetermined length may be cut from an upstream filter cartridge preform of indefinite length by subjecting the preform to forced cooling air to thereby minimize (if not eliminate entirely) significant filter cartridge shrinkage over time.

Abstract: Substantially constant tension is maintained on a melt-blown nonwoven fibrous sheet by mounting the sheet take-up roller for longitudinal movements relative so as to accommodate the increasing diameter of the sheet material being wound convolutely on the take-up roller. Sheet tension during production is thereby maintained substantially constant by virtue of a continual increase in the longitudinal distance (in relation to the machine direction) between the fiber collection mandrel and the take-up roll. Preferably, tension control is achieved by a pneumatic pressure-regulating system which includes at least one rotatable press roller which is longitudinally fixed in position relative to the collection mandrel and is in contact with the sheet material being wound around the take-up roll. The take-up roller is pneumatically advanced toward the press roller by the pneumatic actuation of at least one air cylinder.

Abstract: Substantially constant tension is maintained on a melt-blown nonwoven fibrous sheet by mounting the sheet take-up roller for longitudinal movements relative so as to accommodate the increasing diameter of the sheet material being wound convolutely on the take-up roller. Sheet tension during production is thereby maintained substantially constant by virtue of a continual increase in the longitudinal distance (in relation to the machine direction) between the fiber collection mandrel and the take-up roll. Preferably, tension control is achieved by a pneumatic pressure-regulating system which includes at least one rotatable press roller which is longitudinally fixed in position relative to the collection mandrel and is in contact with the sheet material being wound around the take-up roll. The take-up roller is pneumatically advanced toward the press roller by the pneumatic actuation of at least one air cylinder.