Method of making self-supporting tubular filter

Claim 1

The process of making a self-supporting tubular filter comprising the steps of: (a) providing a sleeve of filter material having a longitudinal line of weakness therealong, (b) providing a core pin having outer dimensions slightly less than the inner dimensions of said sleeve and including a longitudinal channel therealong, (c) inserting said core pin into said sleeve with said longitudinal line of weakness aligned above said channel, (d) providing a first female mold having a cavity complementary to said ensleeved pin, said cavity including a longitudinal groove therealong, (e) enclosing said ensleeved pin inside said first female mold with said line of weakness, said channel and said groove in alignment, (f) injecting a thermoplastic material into said channel of said core pin until said channel becomes filled and said injected thermoplastic material forces outwardly against said sleeve at said longitudinal line of weakness separating said sleeve thereat and filling said groove of said female mold, (g) allowing said thermoplastic material to solidify while in contact with said separated sleeve so that said solidified material in said filled channel and groove form an integral rib splicing said sleeve, said rib being attached to the internal surfaces of said sleeve adjacent to said separation and extending through said separation a predetermined distance external to said sleeve, (h) removing said ensleeved core pin from said first female mold, (i) providing a second female mold having a cavity complementary to said ensleeved pin, said second female mold cavity including a longitudinal groove therealong having the capacity to receive said portion of said rib external to said sleeve, (j) enclosing said ensleeved pin inside said second female mold with said portion of said rib external to said sleeve and said groove of said second female mold cavity in alignment, (k) injecting thermoplastic material into said groove of said second female mold cavity until said groove is filled and allowing said injected thermoplastic material to solidify so that it overlies and attaches to the external surfaces of said sleeve adjacent to said separation, (l) removing said ensleeved pin from said second female mold; and (m) removing said sleeve from said core pin; whereby a self-supporting tubular filter having an integral rib splicing a longitudinal separation of said sleeve both internally and externally is formed.