Patent Document

This application is a divisional of U.S. patent application Ser. No. 09/440,864 filed Nov. 16, 1999 and now U.S. Pat. No. 6,386,390. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to a neck finish on a container having an anti-thread distortion feature and more particularly relates to a neck finish for a container having a clearance designed into a bottle thread to allow horizontal withdrawal of bottle thread molding surfaces during manufacture. 
     Currently, in the forming of containers of plastic, glass, or other known materials, an extruded parison or injection molded preform is initially formed. In the use of plastics, materials such as polyethylene terephthalate (PET) or High Density Polyethylene (HDPE) are most commonly found. In the blow molding process for a container, the preform is positioned within a mold cavity which is defined by the coming together of two mold halves and the preform is held in place by the neck finish between the mold halves. In the molding process the preform is longitudinally stretched, usually by a push rod, and then laterally expanded by injection of a blowing gas or fluid into the interior of the preform. Upon completion of the molding process the mold halves are moved apart horizontally and in many instances during the separation of the mold surface, and particularly in the neck finish, the molding surfaces pull, tear, or rip the helically-shaped formed bottle container neck threads. A common problem found in the forming of containers utilizing steep-pitch threads is distortion of the threads upon removal of the container from the mold. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a neck finish for a bottle container including an anti-thread distortion feature. 
     It is another object of the present invention to provide a neck finish for a container which includes a clearance designed into a bottle thread to allow horizontal withdrawal of the bottle thread molding surfaces during the molding operation of a container without pulling, tearing, ripping, or otherwise deforming threads on the neck of the container. 
     It is yet another object of the present invention to provide a neck finish for a container which allows for the use of steep-pitch threads. 
     In accordance with the present invention, a blow molded container is formed from a parison. The neck finish of the container has been modified to assist in the separation of the mold upon the completion of the formation of a container without deforming the container thread profile. The neck finish is provided with a pair of recesses on opposed sides of the neck and also of the mold, each recess being disposed within a thread of the neck and in alignment with the direction of movement of the axially moveable mold sections which make up the container forming mold. 
     More particularly, the present invention provides a container with a neck portion having a first open end and an opposed second end opening into a body portion of the container. A helical thread of the type such as a steep-pitch helical thread or the like encircles the neck. The helical thread is provided for engagement with mating threads of a closure or container cap. A pair of recesses are provided within the helical thread wherein the recesses are spaced 180° apart. The recesses are formed by fingers in at least two axially movable mold sections. When the mold sections are joined together they form a mold cavity from which the container is formed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A better understanding of the invention will be bad upon reference to the following description in conjunction with the accompanying drawings in which like numerals refer to like a parts throughout the several views and wherein: 
     FIG. 1 is a perspective view of a neck finish of one preferred embodiment of the present invention; 
     FIG. 2 is a side view of the neck finish of FIG. 1; 
     FIG. 3 is a side view of the embodiment of FIG. 1 wherein the container in FIG. 2 has been rotated 90°; 
     FIG. 4 is a top view of the container of FIG.  1 . 
     FIG. 5 is a top view of the container of FIG. 1 in a split mold; and, 
     FIG. 5A is FIG. 5 with the split mold in a separated condition. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As shown in FIGS. 1-4, a container  10  is made up of a neck portion  12  and a body portion  24 . The neck  12  is provided with an open mouth  16  and an opposed opening into the body portion  24 . Circumscribing the neck portion  12  is a helical thread  14  which is defined by a slot  26  which receives the thread of a closure or container cap (not shown). Disposed within the thread  14  is a pair of recesses  20   a  and  20   b  which are spaced from each other a total of 180°. The recesses  20   a  and  20   b  are in alignment with and formed by the fingers  32   a ,  32   b ,  32   c , and  32   d  as shown in FIG. 5 a . A latching lug  22  may also be provided for engagement with a mating latching lug on a closure (not shown). 
     As shown in FIGS. 5 and 5 a , a mold  30  of the preferred embodiment is comprised of only two sections which are, in fact, halves. One half is identifiable as  30   a  and the other as  30   b . Molds  30   a  and  30   b  are horizontally movable by virtue of the fact that there are but two sections. When three or more sections are used, the mold sections move apart axially instead of horizontally. When the molds are in a closed position, as shown in FIG. 5, they define a cavity (not shown) for the mold of the body portion  24  of the container  10  and grasp the neck portion  12  therein and form the helical threads  14 . Helical thread  14  has a pitch in the range of 0 to 8 threads per inch. As shown in FIG. 5 a , the recessed portions  20   a  and  20   b  in the helical thread  14  are formed by the fingers  32   a ,  32   b ,  32   c  and  32   d  of the mold halves  30   a  and  30   b , respectively. The horizontal recess formed by recessed portions  20   a  and  20   b  comprise a first notch disposed on a first side of the slot and a second notch disposed on a second side of the slot with the first notch juxtaposed relative to the second notch so as to horizontally traverse the slot. 
     In the preferred embodiment, a container  10  with a neck finish  12  of the present invention is formed by placing a parison of a selected moldable material, such as, for example polyethylene terephthalate (PET), or High Density Polyethylene (HDPE), within a cavity of the mold. The preferred embodiment also creates the mold cavity upon the bringing together of the mold halves  30   a  and  30   b , as shown in FIG.  5 . Alternate embodiments using more than two mold sections create a mold cavity when their mold sections are brought together axially. A vertically molded core (not shown) of a molding device is inserted into the cavity thereby engaging with the parison. 
     In a form of compression-molding, the parison is next formed into a preselected configuration defined by the spatial relationship of the core and the cavity in the mold  30  resulting in the formation of a container  10 . Additionally, a blow-molding process can be used to create the container  10 . 
     After the container  10  has been formed, the mold halves  30   a  and  30   b  are then horizontally separated as the mold halves  30   a  and  30   b  move horizontally away from the container. Furthermore, at the initial separation of the mold halves, the fingers  32   a ,  32   b ,  32   c  and  32   d  form the recesses  20   a  and  20   b  in the helical thread  14  in order to allow clearance of the mold from the neck finish and avoid distortion of the helical thread  14 , even if the helical threads  14  are of a steep pitch, as the halves  30   a  and  30   b  separate. 
     The foregoing detailed description is given primarily for clearness of understanding and no unnecessary limitations are to be understood therefrom for modifications will become obvious to those skilled in the art upon reading this disclosure and may be made without departing from the spirit of the invention and scope of the appended claims.

Technology Category: 7