Multiple cavity container with method and apparatus for forming the same

Abstract

A plastic container for liquid or the like has an open top, with exterior threads to receive a cap, opening into a main cavity defined by the wall of the container. An inward depression is formed in the wall of the container and formed with threads so that the outer wall of the main cavity forms the interior wall of a secondary cavity. A threaded cap mates with the threads formed on the secondary cavity to close the secondary cavity. The container is preferably formed by blow molding a parison or a stretched molded tube formed with an exterior thread. One of the blow mold halves includes an interiorly extending rotatable protuberance, formed with threads, which create threads on the interior of the second cavity. As the molds are retracted, the protuberance is rotated to separate from the formed threads on the wall of the secondary cavity.

1 . A multi-cavity container having an outer wall and bottom and an open top, communicating with a main cavity defined by the wall and bottom; 
 a secondary cavity formed by a depression in the outer wall extending inwardly toward the center of the main cavity;    screw threads formed about the perimeter of the depression adjacent the outer wall of the container, and    caps adapted to close off the main cavity and the secondary cavity.    
   
   
       2 . The container of  claim 1  wherein the depression in the side wall of the container forming the secondary cavity is cylindrical.  
   
   
       3 . The container of  claim 1  which is formed by a blow molding process which also forms threads about the perimeter of the depression forming the secondary cavity.  
   
   
       4 . The container of  claim 3  formed by a pair of mold halves including one mold half which has an inwardly extending protrusion rotatably supported within the wall of the mold half, thread producing formations on the sides of the protrusion within the die half, and means for rotating the protrusion relative to the mold half as it is withdrawn from the finished product, so as to release threads formed on the interior of the depression forming the secondary cavity from the thread-producing formations on the exterior of the protrusion.  
   
   
       5 . The container of  claim 1  including a plurality of depressions in the outer wall forming second and subsequent secondary cavities  
   
   
       6 . The method of forming a blow molded, multi-cavity container, having a side wall defining a main cavity, an inwardly directed depression in the side wall defining an interior wall of a secondary cavity, and threads formed about the perimeter of said depression adjacent to the container side wall, comprising: 
 disposing a parison between two halves of an open mold, one half having a cylindrical member rotatably supported in the mold wall and extending into the mold cavity and containing projections on its outer surface capable of forming threads;    closing the mold and introducing gas to the interior of the parison to expand the parison against the mold to form a container having a central cavity and a depression formed by the cylindrical member;    and rotating the cylindrical member as the mold halves are opened to release the cylindrical member from threads formed on the interior of the depression on the side wall of the resulting container.    
   
   
       7 . A blow molding tooling for forming a container having a main cavity enclosed by an outer wall and at least one threaded secondary cavity formed by a depression in the outer wall and extending inwardly toward the center of the main cavity, said tooling including one mold half which has an inwardly extending protrusion rotatably supported within the wall of the mold half to form said depression, and thread-producing formations on an exterior surface of the protrusion within the mold half, said tooling further comprising means for rotating the protrusion relative to the mold half as the mold half is withdrawn from the finished product, so as to release threads formed on the interior of the depression forming the secondary cavity from the thread-producing formations on the exterior of the protrusion.