Abstract:
The neck of a container has a smooth seal surface engaged by the inner skirt or plug of a cap. Such surface is free of trim and parting line flaws which are characteristic of blow-molded jars because the surface is formed in such a way that the seal surface is not in contact with mold parting lines and further the trim (excess plastic) of the neck is located away from the sealing surface. In one form of the disclosure, above the sealing surface the neck wall slants outward and then bends upward-inward in a short, tapered stretch about 18 degree to the horizontal which engages the underside of the cap disk to compress against the disk or a liner or foil. Other forms of seal surfaces are disclosed In another form of the invention, above the seal surface the neck extends outward and then upward and then inward in a flange which is trimmed along a line which has a circumference no less than the circumference of the seal surface. The exterior of the neck is formed with shoulders or screw threads which engage over locking beads or threads on the interior of the outer skirt of the cap. Caps suitable for combination with the neck, methods of forming the neck and mold apparatus for forming the neck are also disclosed.

Description:
RELATED APPLICATIONS 
     This application is a Continuation-in-Part of U.S. patent application Ser. No. 09/412,035, filed Oct. 4, 1999 and now abandoned, and a Continuation-in-Part of U.S. patent application Ser. No. 09/365,432, filed Aug. 2, 1999 and now U.S. Pat. No. 6,241,111. 
     Said U.S. patent application Ser. No. 09/412,035 is a Continuation-in-Part of U.S. patent application Ser. No. 08/894,189, filed Jul. 29, 1997 and now U.S. Pat. No. 6,003,699, and a Continuation-in-Part of U.S. patent application Ser. No. 08/847,928, filed Apr. 28, 1997 and now U.S. Pat. No. 5,964,362. 
     Said U.S. patent application Ser. No. 09/365,432 is a Continuation-in-Part of said U.S. patent application Ser. No. 08/894,189, and a Continuation-in-Part of said U.S. patent application Ser. No. 08/847,928. Said U.S. patent application Ser. No. 08/894,189 is a National Stage of International Application No. PCT/US96/00639, filed Jan. 16, 1996 and now International Publication No. WO96/24526. 
     Said U.S. patent application Ser. No. 08/847,928 is a Continuation-in-Part of U.S. patent application Ser. No. 08/385,808, filed Feb. 9, 1995 and now abandoned. 
     Said International Application No. PCT/US96/00639 is a Continuation-in-Part of said U.S. patent application Ser. No. 08/385,808. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a new and improved blow molded neck construction for a bottle or other container, a cap therefor, a method of forming the neck, and molds for forming the neck. More particularly, the present invention relates to a neck finish for a blow molded plastic bottle characterized by the fact that when used with a cap having a plug, for example, an inner skirt, the surface of the neck against which the plug seals is a seal surface without parting lines or parting line defect. A portion of the neck above the seal surface includes an inward directed thin flexible flange and no portion of the neck has a diameter less than that of the seal surface. Hence, the plug seals against a smooth surface and leakage is prevented. 
     Description of Related Art 
     An exemplar of the prior art is U.S. Pat. No. 4,691,834 (“the 834 patent”) which shows an upward inward directed flexible flange sealing against the corner of the intersection of the outer wall of the plug and the underside of the top of the cap. The neck sealing surface is, inherently, somewhat uneven and ragged since the neck is cut or sheared adjacent this sealing surface. In the present invention, however, the neck is trimmed on the edge above and removed from the seal surface, i.e., the trimmed edge is not the portion of the neck which seals against the cap plug. The references cited against the &#39;834 Patent are likewise distinguishable. 
     U.S. Pat. Nos. 4,625,876 and 4,798,301 show curved plug contacting surfaces but these are of substantially the same diameters as the inner edge of the flanges which engage the underside of the top of the cap. 
     U.S. Pat. No. 4,699,286 shows a neck and cap which, in shape, resemble portions of the present invention. The seal surface, however, is between the inwardly extending upper lip of the bottle neck and the a downwardly depending annular plug portion of the cap. Such a sealing surface is, inherently, somewhat uneven and ragged because the neck, like that of the &#39;834 patent above, is cut or sheared adjacent this seal surface. 
     Similarly, the &#39;287 patent also shows a neck and cap which, in shape, resemble portions of the present invention. One seal surface, however, is between the inwardly extending upper lip of the bottle neck and a downwardly depending annular plug portion of the cap. Such a sealing surface is, as noted above, inherently uneven and ragged because the neck is cut or sheared adjacent this sealing surface. 
     SUMMARY OF THE INVENTION 
     The bottle of the present invention is blow molded in a split mold by techniques well known in the art. The surfaces of the mold which define the neck structure cause the neck shape hereinafter described. An upper portion of the parison above the neck is trimmed or cut from the neck according to conventional practice (e.g. pull-up trim, spin trim, ram-down, etc.). In one neck structure, the circle at which the upper portion of the parison is severed from the neck is the inner edge of an inward-upward slanted flange. The other end of the flange merges into a curved surface which extends inward a greater distance than the aforesaid edge to merge with an internal sealing surface of lesser diameter than said edge. The neck structure above the neck sealing surface may have rapidly changing diameters which form a flexible membrane due to parison stretching in the blow molding process. In one form of the invention, below the sealing surface the exterior of the neck structure slants downward-outward to a horizontal shoulder and then extends downwardly and then outwardly to a second or lower shoulder. Other cap engaging means may be used. 
     Many of the illustrated modifications of the present invention include neck finishes and caps of the “snap-on” variety. In accordance with the present invention, however, screw caps wherein the neck and cap skirt have complementary threads are also illustrated. The fact that the same upper neck structure may be used either with a snap-on or a screw-on cap thus becomes apparent. 
     A cap with which the neck is used has a top having a depending central plug or inner skirt. The outer surface of the plug or inner skirt seals tightly against the sealing surface of the neck. The cap can also include an outer skirt having internal sealing beads which engage the upper and lower shoulders of the neck to hold the cap in place. Such an outer skirt is not a necessary feature of the present invention because the primary sealing action takes place between the outer surface of the central plug and the sealing surface of the neck. Such a skirt, however, provides an additional tamper-evident feature. Alternatively, the neck may have threads which are engaged by threads on the cap skirt. The lower portion of the outer cap skirt may be removed by the user engaging and pulling a pull tab which causes the lower part of the skirt to disengage at a circumferential score line. Until such lower skirt is removed, the cap and neck are tamper-evident. Other types of neck engaging means may be employed. 
     Several different ways may be employed to form the neck finishes of the present invention in blow molding operations. One such means employs a conventional blow mold wherein a blow dome is formed above the neck finish with several abrupt bends in the parison between the blow dome and the neck sealing surface. The blow dome is trimmed from the neck in a conventional trimming operation. 
     In another modification of the invention, the shear steel located above the neck finish insert has a projecting extension which is engaged by an outward projection on the blow pin so that when the blow pin is withdrawn, the two extensions shear the parison above the sealing surface of the neck. 
     In still another form of the invention, the shear steels have inward projections, and the blow pin has an enlarged upper diameter so that as the molds come together the shear steel projection cuts the parison by shearing against the enlargement of the blow pin. 
     In still another form of the invention, the shear steel is formed with an outward projection and the blow pin is formed with an outward projection below the level of the shear steel. When the blow pin is raised, the two projections shear the excess parison. In this form of the invention the neck finish is approximately vertical above the sealing surface. 
     The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of a neck portion of a container in accordance with the present invention partially broken away to reveal structure. 
     FIG. 2 is an enlarged sectional view of the neck structure and a portion of a blow dome superimposed thereabove. 
     FIG. 3 is a side elevational view of a snap-on type cap with which the neck of FIG. 1 is used, the cap being partially broken away in section to reveal internal construction. 
     FIG. 4 is an enlarged sectional view of a portion of the cap shown in FIG.  3 . 
     FIG. 5 is a further enlarged fragmentary top plan view of a portion of the cap of FIG. 3 showing a top view of a pull tab. 
     FIG. 6 is a fragmentary sectional view of the portion of the cap of FIG. 3 taken substantially along line  6 — 6  of FIG.  5 . 
     FIG. 7 is an enlarged sectional view schematically showing the seating of the cap of FIG. 3 on the neck of FIG.  1 . 
     FIG. 8 is a view similar to FIG. 7 of a prior art device. 
     FIG. 9 is an enlarged view of a modified neck structure similar to that shown in FIG.  1  and showing an alternate seal area. 
     FIG. 10 is a view similar to FIG. 7 of a modified neck and cap. 
     FIG. 11 is a view similar to FIG. 7 of another modified neck and cap. 
     FIG. 12 is view similar to FIG. 7 of another modified neck and cap. 
     FIG. 13 is a view similar to FIG. 7 showing possible distortion of the cap top if pressure is applied to the container. 
     FIG. 14 is a view similar to FIG. 7 of another modified neck and cap. 
     FIG. 15 is a view similar to FIG. 7 of another modified neck and cap. 
     FIG  16  is a vertical sectional view through a modified container neck and portions of a mold and a blow pin forming same. 
     FIG. 17 is a view similar to FIG. 16, showing the blow pin in a raised position. 
     FIG. 18 is a fragmentary vertical sectional view through a portion of a mold, a blow pin and parison, with the mold in an open position. 
     FIG. 19 is a view similar to FIG. 18 with the mold in a closed position. 
     FIG. 20 is a view similar to FIG. 19 after air has been blown into the mold. 
     FIG. 21 is a view similar to FIG. 2 of a modified neck wherein screw threads are formed on the exterior of the neck. 
     FIG. 22 is a view similar to FIG. 7 showing the neck of FIG. 21 with a cap applied thereto. 
     FIG. 23 is a fragmentary vertical sectional view through a portion of a modified neck similar to that shown in FIG.  22 . 
     FIG. 24 is an enlarged view of neck structure similar to that shown in FIG.  23 . 
     FIG. 25 is a fragmentary sectional view similar to FIG. 20 of a further modified mold and blow pin assembly with parison after air has been blown into the mold. 
     FIG. 26 is a fragmentary sectional view of a neck formed by the mold and blow pin assembly of FIG. 25 and a cap seated thereon. 
     FIG. 27 is a view similar to FIG. 25 of another modified mold, blow pin and parison showing the blow pin in raised position. 
     FIG. 28 is a view similar to FIG. 27 showing the blow pin in lowered position. 
     FIG. 29 is a view similar to FIG. 7 showing a neck similar to that shown in FIG. 28 with a cap seated thereon. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with the preferred embodiments, it will be understood that they are not intended to limit the invention to those embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. 
     As shown in FIGS. 1-7, neck  11  is formed on a thin-walled jar or other container and has a curved primary seal surface  12  which is very smooth and is distinguished by the absence of parting lines or parting line defects inasmuch as it is formed by air pressure or other mechanical means during the blow molding process. Primary seal surface  12  is not formed by the mold halves and thus does not have a mold parting line or associated parting line defects formed therein. As shown in FIG. 2, the seal surface  12  can be curved. Further, the primary sealing surface has minimal ovality, by reason of the way it is formed. Above surface  12  the neck structure extends outwardly in a outward stretch  13  which terminates in an upward bend  14 . Above bend  14  is a thin, tapered upward-inward extending flange  16 , the inner edge of which is of greater diameter than the diameter of surface  12 . Below surface  12  the neck extends downwardly-outwardly in a slanted stretch  17  which terminates in a short vertical stretch  18 , there being an inward directed substantially horizontal upper shoulder  19  below surface  18 . Vertical stretch  21  extends downwardly from the inner edge of shoulder  19  terminating in an inwardly curved portion  22  which merges with an outward-downward stretch  23 . An approximately vertical short surface  24 , which has a greater diameter than surface  18 , terminates in a second or lower horizontal inward directed shoulder  26 . Vertical stretch  27  depends from the inner edge of shoulder  26 , merging with an outward bend  28  which merges with an outward-downward stretch  29 . The lower end of stretch  29  merges with a downward stretch  30  which, in turn, merges an inward-downward stretch  31 . 
     In accordance with one form of standard blow molding practice, a parison of plastic material from which the container is to be formed is deposited in the split mold. It will be understood that the type plastic used to mold the container and the neck may be any suitable relatively hard plastic such as polyethylene. Air is blown into the parison to expand it to fill the mold. In one form of the present invention, the mold has an insert which shapes the finish of the neck of the container heretofore described and above the neck insert the mold widens out to establish what is known as a blow dome of excess material. In accordance with one form of the present invention, as distinguished from prior neck finishes, the blow mold is severed at the inner edge of flange  16 , as by trimming. Severing the edge of the neck from the blow dome may cause a rough surface. One of the advantages of the present invention is that the edge of flange  16  at which the blow dome is severed is not the primary sealing surface. Instead, primary seal surface  12  is located below and removed from the trimmed edge of flange  16 . 
     The blow dome may be severed or sheared from the neck by such methods as trimming to diameter, or by other methods including a subsequent shearing operation on a separate machine or including the use of shear inserts on the molding apparatus. Other well-known means may shear the blow dome from the neck finish so long as the shear edge is not the primary sealing surface. Likewise, other means may be used for terminating the inner edge of flange because that the inner edge does not engage the cap used therewith in a sealing fashion. 
     Directing attention to FIG. 2, a blow dome  33  has an outward-upward slanted stretch  34  merging into a curved stretch  36  which has an inward slanted stretch  37 . The cut line  38  is a circle wherein the stretch  34  is severed from the inner edge of flange  16 . Preferably flange  16  should terminate so that it does not engage the plug of the cap in a sealing fashion. By reason of the almost 180° bend  14 , and the rapid diameter changes within a relatively short vertical distance, flange  16  is thin and flexible. 
     One form of closure or cap  41  used with the present invention is shown in FIGS. 3-7. The closure of FIGS. 3-7 comprises an indented circular top  42  having a short peripheral cylindrical upward extending member  43  from which extends outwardly a stack rim  44 . The outer edge of rim  44  has a depending downward stretch  46  which merges into a vertical, substantially cylindrical upper outer skirt  48 . The lower end of upper outer skirt  48  merges into an outward-downward slanted stretch  55 . Below stretch  55  is a substantially cylindrical lower outer skirt  49 . An internal score line or line of weakness  51  separates stretch  55  from lower skirt  49 . Below lower skirt  49 , cap  41  has an outward-downward slanted flange  52  which, for practical purposes, rests against outward-downward surface  29  of neck  11 . Interrupted upper inner bead sections  53  engage under shoulder  19  of neck  11 . Lower inner bead  54  located at the lower end of skirt portion  49  engages under shoulder  26  of neck  11 . When cap  41  is attached to neck  11 , beads  53  and  54  prevent cap  41  from being removed from neck  11 . In order to enable the user to grip cap  41 , ribs  50  extend outwardly from upper outer skirt member  48  merging with the outer surface of lower skirt portion  49  as best shown in FIG.  7 . Ribs  50  also impart columnar strength to the closure to transfer vertical force and prevent closure collapse during axial application of the closure to the neck finish. 
     At one portion of the circumference of lower skirt  49 , as best shown in FIGS. 5 and 6, spaced outwardly therefrom is a horizontal pull tab  57  having a curved connection  58  to lower skirt  49 . The interior of skirt  49  is formed with a notch  59  where tab  57  joins lower skirt  49 . Notch  59  forms a vertical line of weakness through lower skirt  49 . Enlargement  61  is formed on the distal edge of pull tab  57 . A portion of flange  52  is formed thinner than the rest of flange  52  in a thin area  62  adjacent tab  57 . 
     Cap  41  includes a downward extension of cylindrical member  43  which forms a depending inner skirt extension  66 . The lower inner edge of depending inner skirt extension  66  is formed with a radius  67 . The inner surface of cylindrical member  43  seals against primary seal surface  12 . A vertical position of cap top  42  can be adjusted to provide for compression of surface  12  against the adjacent surface of member  43 . 
     Directing attention to FIG. 7 it will be seen that the surface  12  is the primary sealing surface against the member  43 . As has been noted, the surface  12  is very smooth and hence forms a very effective seal against the member  43 . 
     When the cap is applied, beads  53  and  54  lock under shoulders  19  and  26  to prevent removal of cap  41  from neck  11  and hence are tamper evidencing. When the user wishes to open the container, the user grips the enlargement  61  and bends pull tab  57  outwardly and then pulls circumferentially, tearing lower skirt  49  from upper cap portion, namely, from upper skirt  48 . The user may then grip under surface  55  which, as shown in FIG. 7, is spaced from the bottle neck finish by a considerable gap, and pull upwardly causing the interrupted upper bead segments  53  to disengage from shoulder  19  so that cap  41  may be removed from neck  11 . The ribs  50  rigidify the upper portion of the cap to allow the forces necessary to push the cap onto the bottle from causing the cap to buckle. The portion of the cap above score line  51  constitutes a reclosure cap  41  and may be pressed back on neck  11  after portions of the contents of the jar or container are dispensed as frequently as required. 
     Comparison of FIG. 7 with prior art structure shown in FIG. 8 shows that in the present invention the very smooth surface of primary seal surface  12  causes a tight seal against the exterior of member  43  and flange  16  need not seal at all, whereas in the prior art the cut inner edge of flange  16   a  is a primary seal. The primary seal surface  12  of the present invention has minimum deviation from ovality as compared to FIG. 8 where the prior primary seal  12   a  is coincident with a trim surface of flange  16   a . Bottles of the type of this invention and the prior art were molded. The ovality of the two types was measured. The unexpected result of these experiments was that the current invention produced a significantly more circular primary seal area  12 . Refer to Table A for tabulated results. The stretch occurring on both sides of the primary seal  12  is primarily contributing to the superior ovality and differentiate it from the prior art. 
     
       
         
               
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
               
               
             
           
               
                 TABLE A 
               
             
             
               
                   
               
               
                 STD BOTTLE STYLE 
                 PRESENT INVENTION 
               
             
          
           
               
                 Run 
                 Run 
                 Run 
                 Run 
                 Run 
                 Run 
                 Run 
                 Run 
               
               
                 A 
                 B 
                 C 
                 D 
                 A 
                 B 
                 C 
                 D 
               
               
                   
               
             
          
           
               
                 0.055 
                 0.020 
                 0.048 
                 0.028 
                 0.024 
                 0.058 
                 0.002 
                 0.015 
               
               
                 0.053 
                 0.002 
                 0.056 
                 0.015 
                 0.006 
                 0.010 
                 0.106 
                 0.030 
               
               
                 0.062 
                 0.000 
                 0.044 
                 0.010 
                 0.017 
                 0.002 
                 0.013 
                 0.010 
               
               
                 0.043 
                 0.010 
                 0.058 
                 0.003 
                 0.016 
                 0.004 
                 0.005 
                 0.027 
               
               
                 0.058 
                 0.029 
                 0.025 
                 0.009 
                 0.014 
                 0.013 
                 0.005 
                 0.034 
               
               
                 0.064 
                 0.016 
                 0.055 
                 0.003 
                 0.011 
                 0.060 
                 0.017 
                 0.017 
               
               
                 0.011 
                 0.005 
                 0.059 
                 0.002 
                 0.004 
                   
                 0.003 
                 0.017 
               
               
                 0.019 
                 0.013 
                 0.049 
                 0.005 
                 0.007 
               
               
                 0.042 
                 0.006 
                 0.045 
                 0.002 
                 0.013 
               
             
          
           
               
                 Average 0.028 
                 Average 0.016 
               
               
                   
               
             
          
         
       
     
     FIG. 9 illustrates a modified shape of a neck  11   b  wherein seal surface  12   b  is cylindrical rather than curved. As shown in FIG. 9, the seal surface can be vertical, such as seal surface  12   b , or it may be curved, such as seal surface  12  shown in FIG.  2 . 
     Directing attention to FIGS. 10-12, various other modifications may also be made to the neck and cap of the present invention. For example, FIG. 10 discloses an embodiment in which the primary sealing surface is disposed non-vertically and is instead an angled surface, such as seal surface  12   c  shown in FIG.  10 . Upwardly extending member  43   c  of cap  41   c  includes a lower frustoconical portion  45  which depends from top  42   c  at an angle. Neck  11   c  includes a non-vertical, very smooth sealing surface  12   c , an outward bend joining said sealing surface  12   c  to an outward stretch  13   c , an upward bend  14   c  joining outward stretch  13   b  to a flange  16   c . Surface  12   c  is the primary sealing surface against lower portion  45  of member  43   c . The very smooth surface of primary seal surface  12   c  causes a tight seal against the exterior of member  43   c  whereby flange  16   c , which is joined to outward extending stretch  13   c , need not seal at all. The embodiment shown in FIG. 10 includes a further modification in which a lower portion of lower skirt  49   c  frictionally engages vertical stretch  27   c  thus obviating need for an inner bead. An internal score line  51   c  separates lower skirt  49   c  from upper skirt  48   c.    
     FIG. 11 discloses an alternative embodiment of the neck and the cap. Neck  11   d  includes a very smooth sealing surface  12   d , an outward directed stretch  13   d  joining sealing surface  12   d  to an upward directed stretch  130 , and an inward directed stretch  131  joined to upward stretch  130 . Inward stretch  131  terminates in an edge  132  which has a diameter greater than the diameter of seal surface  12   d  and of member  43   d . The very smooth surface  12   d  causes a tight seal against the exterior of member  43   d  whereby edge  132  need not seal at all. The embodiment shown in FIG. 11 includes a further modification in which cap  41   d  includes a skirt  48   d  having an upper inner bead  53   d , and a lower skirt  49   d  having a lower inner bead  54   d . An internal score line  51   d  may separate lower skirt  49   d  from upper skirt  48   d.    
     FIG. 12 discloses an alternative embodiment of the cap without an outer skirt which may be used with the various neck embodiments discussed above. Cap  41   e  includes a top  42   e  having a cylindrical downwardly extending member  43   e  and an outwardly extending stack rim  44   e . Similar to the above embodiments, seal surface  12   e  causes a tight seal against the exterior of member  43   e . Cap  41   e  differs in that outwardly extending rim  44   e  terminates in an outer edge  47  whereby cap  41  has no skirt. As noted above, such an outer skirt is not a necessary feature of the present invention because the primary sealing action takes place between the outer surface of the central plug and the sealing surface of the neck, i.e., between member  43   e  and seal surface  12   e . In the absence of a skirt, other types of tamper-evidencing methods may be employed, for example, shrink-wrapping (not shown). Furthermore, in the absence of a skirt, other methods may also be employed to shield the upper external portion of the neck from debris and contamination. Shrink-wrapping, for example, may again be employed to shield portions of the neck that are otherwise covered by a skirt from dirt. 
     With reference to FIGS. 13-15, if the contents of the container are non-viscous (e.g., brine-packed pickles) or if the walls of the container are easily squeezed during transportation or handling, top  42   f  may be subjected to upward pressure, as indicated by arrow “P” in FIG. 13, causing it to become “domed” (outwardly convex). Such action may cause inner skirt member  43   f  to pivot away from curved primary seal  12   f , resulting in leakage. This effect is illustrated in FIG.  13 . 
     FIG. 14 shows one remedy for such leakage. Contrasting FIG. 14 with FIG. 7 it will be seen that top  42   g  is raised relative to stack rim  44   g  and that the contact of surface  12   g  with inner skirt member  43   g  is more closely opposite top  42   g . FIG. 14 also shows a structure in which top  42   g  is closer to the level of rim  44   g  than in the above embodiments. Surface  12   g  engages the surface of cylinder  43   g  below the level of top  42   g . In addition, reducing the vertical spacing between top  42   g  and stack rim  44   g  reduces the lever arm and corresponding mechanical advantage of the inward force component generated by internal pressure. Hence doming of top  42   g  does not result in pivoting of skirt  66   g  out of sealing contact with surface  12   g . As noted above, FIG. 13 shows how pressure applied to the container (as by squeezing the side wall) may cause top  42   f  to bow upward, pulling plug  66   f  away from such surface  12   f.    
     FIG. 15 shows another remedy for leakage due to doming of surface  42   h . A plurality of angularly spaced, substantially radially gussets  71  are formed at the intersection of top  42   h  and cylindrical member  43   h . Gussets  71  prevent member  43   h  from pivoting away from surface  12   h . A similar result can be achieved by replacing gussets  71  with a continuous reinforcing bead or shoulder at the intersection of the exterior surfaces of top  42   h  and member  43   h.    
     As shown in FIGS. 16 and 17, another way to achieve the neck structure of the present invention is to employ what is commonly referred to as “pull-up” trim. In this case, the cut line is sheared by having a close diametrical fitting of a blow pin positioned internally within the parison and sets of shear steels mounted on the split mold. Diameters of the blow pin are typically 0.001 inch to 0.004 inch smaller than that diameter defined by the shear steels in closed position. After blowing of the neck and the container, a portion  34   i  of the parison above the cut line is severed from the neck portion below the cut line by upward movement of the blow pin relative to the shear steels as shown in FIG.  17 . 
     The modification shown in FIGS. 16 and 17 illustrates the formation of a modified container neck  11   i . Such a neck may resemble that shown in FIGS. 1 and 2 of U.S. Pat. No. 4,699,287, (“the &#39;287 patent”) with an important modification, as hereinafter explained. In FIG. 16, the parison forming neck  11   i  is shown between a blow pin  86  and shear steel  76  and neck insert  81  as molding is being completed. 
     With continued reference to FIG. 16, shear steel  76  has an inward projection  77  terminating in a vertical inward extending shearing edge  78 . Blow pin  86  has a lower cylindrical portion  87  having an outward extending shearing edge  88  with a groove  89  thereabove. 
     As shown in FIG. 16, blow molding of the parison to the shape of shear steel  76  and neck insert  81  has just been completed. The shape of the parison generally resembles the neck shown in the &#39;287 patent. Edge  88  is located below edge  78 . Air blowing through hole  91  has formed vertical stretch  101  of flange  100  and inward horizontal stretch  102  as well as the portions thereabove. The smooth, vertical, lower cylindrical portion  87  has formed internal primary seal surface  12   i.    
     The blow pin  86  then moves from the position of FIG. 16 to the position of FIG.  17 . The neck structure is sheared between edges  78  and  88 . Inner flange edge  96  of neck  11   i  is formed where the edges  78 ,  88  have sheared the same and the parison sheared-off portion  94  thereabove is discarded. 
     It is noted that edge  96  is of a larger diameter than primary seal surface  12   i . Hence, a hollow plug or inner skirt such as that shown in the &#39;287 patent seated on container neck  11   i  seals against surface  12   i  instead of surface  96 . Since blow pin  86  has no parting line, surface  12   i  has no flash, that is, a parting line or parting line defects. Surface  12   i  is smooth and its diameter is always the same during repetitive molds and hence makes a superior seal with the cap plug. 
     Directing attention to FIGS. 18-20, shear steel  76   j  has an inward directed cutting edge  103 , the inside diameter of which is approximately equal to the enlarged diameter of the upper portion  104  of blow pin  86   j . Below cutting edge  103  is an undercut  105 . Neck insert  81   j  has a seal forming projection  106  which has an inside diameter which is greater than the outside diameter of cylindrical portion  87   j  of blow pin  86   j  by a distance slightly less than the thickness of parison  93   j.    
     When the neck molds are closed, the cutting edge  103  cuts off upper portion  94   j  of the parison by reason of edge  103  engaging enlarged outside diameter portion  104  of blow pin  86   j . Seal forming projection  106  squeezes the parison against blow pin lower portion  87   j  to form a smooth, compressed primary seal surface  12   j.    
     As shown in FIG. 20, when air is blown through the pin  86   j , the parison assumes the shape of neck insert  81   j . Thus, neck  11   j  has a primary seal surface  12   j , an outward stretch  13   j , a bend  14   j , and a cut line  38   j . The inside diameter of cut line  38   j  is slightly greater than the primary seal surface  12   j . In other respects the shape of the neck  11   j  resembles that of FIG.  17 . 
     Directing attention to FIGS. 21 and 22, neck finish  11   k  and the portion above the neck finish formed in blow dome  33   k  resembles that of FIG. 2 except that screw threads  127  are formed on the exterior of upper neck surface  126 . Below threads  127 , the neck has an outward curved portion  28   k  which merges with horizontal shoulder  129  against which shoulder  141  on the bottom edge of cap lower skirt  49   k  rests. Depending from shoulder  129   k  are lower ratchet teeth  128  and below teeth  128  is a remainder  146  of neck  11   k.    
     Vertical stretch  137  of cap  11   k  is formed with internal threads  138  which mesh with threads  127 . On the exterior of upper cap skirt  48   k  are vertical ribs  50   k  and on the lower end of stretch  137  is outward directed shoulder  141  from which depend ratchet teeth  147  which mesh with ratchet teeth  128 . Lower skirt  49   k  is joined to shoulder  141  at juncture  148 . Juncture  148  is frangible so that lower skirt  49   k  and internal ratchet teeth  147  thereof may be removed to permit the cap to be unscrewed from the neck. Fracture of juncture  148  indicates tampering with the contents of the container. Below lower skirt  49   k  is a downward-outward directed flange  149  which is in close proximity to remainder  146  of the neck so as to prevent foreign matter from entering between the ratchet teeth. 
     FIGS. 23 and 24 illustrate a modified neck finish  11   l  similar to that shown above and having external screw threads  127   l  formed on the neck structure to replace the snap-on structure described above with reference to FIG.  11 . FIG. 24 is an enlarged view of a portion of FIG. 23 showing the positioning of ratchet teeth  128   l  which are interengaged by internal ratchet teeth on the lower portion of a cap skirt similar to that shown in FIG.  22 . 
     Directing attention now to FIG. 25, a different shape neck is produced by the mold parts therein illustrated. Blow pin  86   m  has a lower tapered portion  111  at the upper end of which is a vertical cylindrical surface  115  which is smooth and terminates at its upper end in a shear corner  114 . Above corner  114  is a cut-away  116 . Blow pin  86   m  may be made of two parts in order to facilitate fabrication. As shown in FIG. 25, lower portion  86   m  is attached to upper blow pin portion  113  and radial grooves or channels  112  are cut in the top surface of blow pin  86   m , the channels  112  being connected to vertical air holes  91   m . Thus when air is blown into blow pin  86   m  air travels up holes  91   g  and out channels  112 . The lower corner of upper blow pin  113  is formed with a cut-away  117  which merges with cut-away  116  to clear inward shearing edge  78   m  of inward extension  77   m  of shear steel  76   m . The upper end of neck insert  81   m  is formed with seal forming projection  106   m  which presses the parison against surface  115 . The neck formed in neck insert  81   m  has external threads and hence grooves  118  for such threads are formed therein. Below the threaded portion of the neck, the bottle may assume any desired shape and hence the details of neck insert  81   m  which form the same are not specifically set forth. 
     After the neck has been blown, as shown in FIG. 25, the blow pin  86   m  is raised and hence the shear corner  114  shears off the parison by shearing action against edge  78   m . Thus the neck has a straight upward section  122  which is a smooth sealing surface characterized by the absence of mold parting lines and also characterized by the absence of rough edges. 
     Directing attention to FIG. 26, the neck  11   m  formed in the mold parts shown in FIG. 25 is illustrated with a cap  41   m  snapped thereon. Thus neck  11   m  has an upper lip  121  below which is a vertical, smooth, seamless seal surface  122  with an enlarged diameter portion  123   m  therebelow. On the outside of the neck  11   m  there is an upper, vertical, straight surface  126   m  below which are external threads  127   m . Below the threads is an outward curved portion  28   m  which merges with an horizontal shoulder  129   m . Below the shoulder  129   m  are outward extending vertical ratchet teeth  128   m , and below the teeth  128   m  is remainder  146   m  of the neck. 
     Cap  41   m  has a top  42   m  with a vertical outer skirt  48   m  depending from the outer edge thereof. Upper skirt  48   m  is connected to lower skirt  49   n  as hereinafter appears. The upper edge of skirt  48   m  is connected to top  42   m  by corner  136 , and below corner  136  is a substantially vertical stretch  137   m , the inner surface of which is formed with internal threads  138   m  which mate with external threads  127   m  of neck  11   m . On the exterior of upper skirt  48   m  are vertical ribs  59   m  which assist the user in unscrewing the cap. An inner filet  140  is formed at the juncture of the underside of top  42   m  and the inside of upper skirt  48   m . The purpose of fillet  141  is to exert pressure against the upper portion of the neck  11   m  to force seal surface  122   m  outwardly. The inner surface of lower skirt  49   m  is formed with ratchet teeth  147   m  which mate with teeth  128   m . The upper inner corners of teeth  128   m  are joined to shoulder  141   m  on the lower end of upper skirt  48   m  at frangible juncture points  148   m . Below lower skirt  49   m  is an outward, downward slanted flange  149   m  which engages the outside of skirt portion  29   m.    
     Depending from top  42   m  is a plug or inner skirt  66   m  having a radius  67   m  at its lower, outer corner. When the neck  11   m  is forced outwardly by fillet  140 , it tightly engages the outside surface of plug  66   m  to form a liquid tight seal. 
     It will be seen that the cap shown in FIG. 26 is tamper-evidencing. When the cap  41   m  is unscrewed, the junctures  148   m  fracture, permitting the cap to be unscrewed but so long as the junctures  148   m  are intact, evidence that the cap has not been opened appears. 
     Directing attention to FIGS. 27-28, a neck similar to that of FIG. 26 is produced. The molding process used is generally known as “ram down” molding in that the blow pin  86   n  is forced down on striker plate  156 . Blow pin  86   n  has an upper cylindrical portion  104   n , a reduced diameter portion  87   n  below portion  104   n , and a curved portion  157  intermediate portions  87   n  and  104   n . A corner  88   n  at the juncture of curved portion  157  and upper portion  104   n  comprises a cutting edge. Neck insert  81   n  resembles that of FIG.  25 . Above neck insert  81   n  is a striker plate  156  having a rounded point  158  which is opposite curved portion  157  when blow pin  86   n  is in down position, as shown in FIG.  28 . The spacing between point  158  and curved portion  157  is slightly less than the thickness of parison  93   n . As shown in FIG. 28, when pin  81   n  is in down position, cutting edge  88   n  engages striker plate point  158  thereby shearing off parison portion  94   n . The parison  93   n  is squeezed between point  158  and curved portion  157 , thereby creating primary seal surface  12   n.    
     FIG. 29 shows the neck structure  11   p  of FIG. 24 with a cap  41   p  seated thereon. Thus it will be seen that the outward stretch  13   p  of neck  11   p  does not engage either the underside of cap top  42   p  nor the plug  66   p  nor the upper skirt  48   p.    
     It will be understood that different neck shapes are shown formed by the various types of molds and molding methods illustrated in the drawings and described herein. However the neck shapes and molding techniques may be interchangeable, as will occur to one skilled in the art. 
     In FIGS. 8-28 the same reference numerals are used for parts corresponding to those elsewhere mentioned, followed by subscripts a, b, c, d, e, f g, h, i, j, k,  1 , m, n and p, respectively. 
     The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.