초록 ▼

Plastic containers having internal reinforcing ribs are formed by a molding operation including pre-blow and final-blow steps. The pre-blow step includes inflating a blowable plastic parison into contact with the cavity walls of a first blow mold to form a blown pre-form, the cavity walls of the fir

Plastic containers having internal reinforcing ribs are formed by a molding operation including pre-blow and final-blow steps. The pre-blow step includes inflating a blowable plastic parison into contact with the cavity walls of a first blow mold to form a blown pre-form, the cavity walls of the first blow mold including a plurality of concave grooves to form a pattern of convex or protuberant ribs on the outer-periphery of the pre-form. The final-blow step includes positioning the blown, ribbed pre-form within a second or final blow mold having a cavity defined by substantially smooth wall surfaces conforming to the exterior configuration of the desired container. Next, the pre-form is blown to stretch and expand against the cavity walls of the second mold, during which step the convex ribs on the exterior of the pre-form are flattened, forming concave portions intermediate convex reinforcing ribs on the internal wall surface of the container.

대표청구항 ▼

A container of thermosplastic material comprising a finish at one end, a peripheral wall, and a bottom wall each having a substantially smooth outer configuration, a plurality of integral, closely spaced localized reinforcing plastic ribs on the interior surface only of at least one of said walls, a

A container of thermosplastic material comprising a finish at one end, a peripheral wall, and a bottom wall each having a substantially smooth outer configuration, a plurality of integral, closely spaced localized reinforcing plastic ribs on the interior surface only of at least one of said walls, and intermediate wall portions between each pair of said closely spaced internal ribs, the thickness of said integral ribs being greater than the thickness of the intermediate wall portions between adjacent, closely spaced ribs, and the intermediate wall portions between each pair of said closely spaced ribs being thicker than other non-ribbed portions of the container wall.