| 摘要 |
A filter having a substantially cylindrical or slightly tapered body design which has a plurality of elongated apertures formed therethrough. Each aperture is defined side to side by a pair of elongated, wedge-like rib members disposed one on each side of each aperture, and top to bottom by a pair of cross members which present a substantially square top side and an angularly declining bottom side. The end effect is a substantially rectangular entry aperture for fluid flow with the exception of the declining bottom side which promotes smooth, low resistance entry flow. The present invention is also directed to a method of manufacture of filters having the above-described characteristics. In particular, the preferred method involves an injection molding process in which a molten plastic (such as high-density polyethylene, HDPE) is injected into a two-part mold. The mold generally comprises a smooth, substantially cylindrical cavity and a notched and grooved core which is inserted into the cavity in a partial surface to surface contact relationship to complete the filter mold. Due to the extremely close tolerances required by such a core and cavity surface to surface relationship, unique mold alignment modifications were also developed.
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