Finish for injection blow molded container

Abstract

An injection molded finish portion of a container preform has an annular wall with an end sealing surface. A set of ratchet teeth are located at a lower end of the annular wall on a flange having upper and lower surfaces including radially inward edges coterminous with the annular wall. A threaded portion is located below the sealing surface and above the ratchet teeth that includes sets of inclined threads extending part way around the annular wall, the threads having crest portions that terminate at planes tangent to the annular wall along parting lines on opposite sides of the finish. Lugs project outward from the annular wall in the vicinity of the parting lines to ensure correct interaction between the ratchet teeth and a cooperating flexible closure.

1 . An injection molded finish portion of a container preform comprising: 
 an annular wall having an outside surface, an end sealing surface on an upper end of the annular wall, a set of ratchet teeth located at a lower end of the annular wall, and a threaded portion located below the sealing surface and above the ratchet teeth, the threaded portion including two sets of inclined threads extending part way around the annular wall, the threads including crest portions terminating at planes tangent to the annular wall along parting lines on opposite sides of the container.    
   
   
       2 . The injection molded finish portion of  claim 1  further comprising lugs projecting outward from the annular wall in the vicinity of the parting lines.  
   
   
       3 . The injection molded finish portion of  claim 2  wherein the lugs extend equally on each side from the parting lines.  
   
   
       4 . The injection molded finish portion of  claim 2  wherein the lugs are aligned with adjacent ends of the threads.  
   
   
       5 . The injection molded finish portion of  claim 4  wherein each lug includes a base portion adjacent to the annular wall defined by a first vertical cross-sectional geometry and a radially outward crown portion defined by a second vertical cross-sectional geometry.  
   
   
       6 . The injection molded finish portion of  claim 5  wherein the first vertical cross-sectional geometry includes arcuate surfaces above and below a midline of the lug, and the second cross-sectional geometry comprises a wedge extending outward from a middle sector of the first geometry arcuate surfaces.  
   
   
       7 . The injection molded finish portion of  claim 4  wherein the lugs comprise an upper lug and a lower lug straddling each parting line, the lower lug crown portion extending radially outward further than the upper lug crown portion.  
   
   
       8 . The injection molded finish portion of any of claims  1 ,  2 ,  3 ,  4 ,  5 ,  6  or  7  wherein the ratchet teeth are disposed on a flange having an upper surface and a lower surface, the flange upper and lower surfaces including radially inward edges meeting with said annular wall.  
   
   
       9 . The injection molded finish portion of  claim 8  wherein the ratchet teeth include a radial surface and an outer surface inclined with respect to the radial surface, outer ends of adjoining radial and outer surfaces being joined by a curved portion and inner ends of adjoining radial and outer surfaces being joined by a segment parallel to said annular wall.  
   
   
       10 . The injection molded finish portion of  claim 9  wherein the outer surface of each ratchet tooth is inclined at about 75° with respect to the radial surface of the same tooth.  
   
   
       11 . The injection molded finish portion of  claim 8  wherein the flange upper and lower surfaces are outwardly tapered so that the flange is thickest at the radially inward edges of the upper and lower surfaces.  
   
   
       12 . The injection molded finish portion of any of claims  1 ,  2 ,  3 ,  4 ,  5 ,  6  or  7  wherein each of the threads is defined by an upper wall and a lower wall, the upper and lower walls extending radially outward from said annular wall, a tapered surface extending downwardly from the upper wall outer extremity, and a curved surface joining the tapered surface to the lower walls, the curved surface defining said thread crest portion.