Patent ID: 7731886
Filing Date: 2010-06-08
Classification: B01D,B29C,Y10T

Abstract:
1. A method of constructing an internally ribbed injection molded hollow tube for a filter element, the method comprising steps of: providing a generally cylindrical male mold member having longitudinally spaced ribs defining grooves and a free end; providing a female mold member adapted to overlay the male mould member in closely spaced relation and define a tube shaped void between the mold members; injecting molding material into the void, said molding material providing a solid-walled substantially rigid tube when cured; removing the female mold member from the male mold member while the tube is in a green state, the grooves in the male mould member retaining the tube in position on the male mould member; and subsequently forcing the tube from the male mold member while the tube is still in a green state to form an internally ribbed injection molded solid-walled hollow tube having an open end, wherein the grooves are not uniformly spaced on the male mold member and further comprising the step of progressively sliding the tube off the male mold member, so that once the initial release of the tube from all of the grooves takes place, ribs formed in the grooves do not all encounter grooves at the same time.