US 3329295 A
Description (OCR text may contain errors)
July 4, 1967 M R, FlELDS 3,329,295
TAMPER- INDICATING CLOSURE Filed Nov. 29, 1965 Fa'sf? 4 35 United States Patent t 3,329,295 TAMPER-INDICATING CLOSURE Mack R. Fields, Lighthouse Point, Fla., assiguor to Zbislaw M. Roehr, Waterbury, Conn.
Filed Nov. 29, 1965, Ser. No. 510,332 14 Claims. (Cl. 21S-40) This invention relates to container closures, and more particularly to improvements in tamper-indicating closures.
It is an object of the present invention to provide a tamper-indicating closure that is screw-threaded over a container neck and has a resilient skirt that is joined to the remainder of the closure by a frangible zone of weakness. The skirt is sufficiently resilient within its elastic limits to expand and allow a preformed lip thereon to pass over an interfering bead or transfer ring on the container as the `closure is threaded onto the container neck. After the lip passes the bead, the skirt contracts to its original shape. Upon unscrewing of the closure, the axial interference between the lip and bead retains the skirt against laxial movement and the unscrewing torque on the closure ruptures it at the zone of weakness, thereby severing the skirt and indicating that the closure has `been removed from the container.
It is a further object of the present invention to provide a tamper-indicating closure of the type stated which does not require any forming or shaping operation after it has been threaded onto the container.
It is also `an object of the present invention to provide a tamper-indicating closure of the type stated having an all plastic cap body in which the skirt is molded integral therewith and joined thereto by spaced bridges of plastic material that constitute the zone of weakness.
It is a further object of the present invention to provide la closure of the type stated in which the lip on the skirt is axially spaced from the container bead when the closure is fully closed on the container so that the initial unscrewing torque on the closure loosens the grip thereof on the container thread and at the same time moves the lip into contact with the bead whereupon further unscrewing torque ruptures the zone of weakness. Since the torque for rupturing the zone of weakness is applied after the initial or loosening torque rather than simultaneously with the loosening torque, the manual effort required to remove the closure is reduced. Furthermore, by designing the closure so that there is a space between the lip and container bead, it is possible -to insure that the lip will always end up beyond the bead when the closure is screwed onto the container, despite variations in dimensional tolerances in the manufacture of the container and the closure.
It is another object of the present invention to provide a tamper-indicating closure of the type stated in which the zone of weakness has a smaller cross sectional area adjacent to the threaded wall of the closure than adjacent `to the skirt so that the break will tend to be at the threaded wall. Thus the break willtend to be relatively free of sharp edges at the edge of the part of the closure that will there- Vic FIG. 2 is a sectional View similar to FIG. 1 and showing, on an enlarged scale, a portion of the closure after it has been partially threaded onto the container neck;
FIG. 3 is a sectional view similar to FIG. 2 showing the closure in its fully closed position on the container neck;
FIG. 4 is an enlarged sectional view of a portion of FIG. 3 and showing one of the bridges of material that forms the rupturable zone of weakness;
FIGS. 5 and 6 are fragmentary sectional views taken along lines 5 5 and 6-6, respectively, of FIG. 4;
FIG. 7 is a fragmentary longitudinal sectional view showing a method of making the closure of the present invention;
FIG. 8 is a fragmentary sectional View taken along lines 8-3 of FIG. 7;
FIG. 9 is a fragmentary elevational View of the lower end of a modified form of closure constructed in accordance with the present invention;
FIG. l() is a fragmentary sectional view taken along line lil-1t) of FIG. 9; and
FIG. 1l is a fragmentary sectional View of the lower end of another moditied form of closure constructed in accordance with the present invention.
Referring now in more detail to the drawing, 1 indicates a closure having a cap body 3. In the present ernbodiment of the invention, the body 3 may be a one piece member of molded plastic material. A commercial grade of high impact polystyrene is suitable for this purpose.
The body 3 includes an end wall 4 and an integral cylindrical side wall 5 that extends axially from the end wall 4. The side wall 5 is formed with an internal thread 7 for threaded engagement with an external thread 9 on the neck 1@ of a container 11, for instance a glass bottle. Adjacent to the end wall 4l the side wall 5 is molded with an undercut cylindrical groove 13 for receiving a disc-like sealing liner 14 which bears against the rim 8 of the container neck Ill to seal the neck opening 16 when the closure is in closed position on the neck 10.
At the lower or free end of the side wall 5 is a depending cylindrical skirt 17 that is joined to the open end 1S of the side wall 5 by circumferentially spaced fracturable bridges 19 of the plastic body material. In the present embodiment of the invention, there are eight equally spaced bridges, but it will be apparent that a greater or lesse-r number of bridges may be used. As best seen in FIGS. 4-6, the Cross sectional area of each bridge is greater at its junction 19a with the skirt 1'7 than at its junction 19b with the free end 1S of the side wall 5.
At its lower or free end, the skirt 17 is molded with a preformed radially inwardly directed .annular lip 20 which, when the closure is in closed position on the neck 10, radially overlaps an annular bead 22 that is integrally formed on and projects radially outwardly from the neck 10 and is axially spaced from the neck thread 9. The bead 22 progressively incre-ases in diameter in a direction axially away from t-he neck thread 9 to a shoulder 24 thereon and below which the lip 2li is located and with there being a gap 26 between the shoulderI 24 and lip 20, for purposes presently more fully appearing. If the container is a glass bottle, the bead 22 may be the so-called transfer ring used to handle the glass bottle during removal thereof from its mold.
The body 3 may be molded with apparatus `of the type shown in copending application Ser. No. 198,107, led May 28, 1962, now Patent No. 3,247,548, in which I am one of the joint inventors, and to which reference may be had. Sufiice it to say that such molding apparatus includes -mold members 25, 27 and a core 28 that is longitudinally divided into circumferentially spaced expandable and collapsible sections 29, 30 that are held in rm abutting relationship in their expanded positions by a center pin 31. The core sections, when in molding position, dei-ine surfaces that are counterparts of the surfaces of the body 3 to be molded. As is more fully explained in the aforesaid application Ser. No. 198,107, the core sections are designed to be capable of radially inwardly collapsing when the center pin 31 is axially withdrawn from supporting relationship with the sections. The amount of collapse is sufficient to clear the lip 20 and other molded undercuts in the body 3 so that the body 3 may be axially separated from the core 19. For purposes of the present invention, the core sections are formed with longitudinal slots 33 at which the solidified plastic becomes the bridges 19. Thus, when plastic is injected into the mold through the gate 35, the slots 33 form, in effect, secondary gates through which the pl-astic ows to ll the part of the mold -cavity that defines the skirt 17.
The closure is initially threaded onto the neck until the lip 20 makes contact with the bead 22 above the shoulder 24, as shown in FIG. 2. At this time the rim 8 is spaced from the liner 14 and the threads 7, 9 are still in relatively loose engagement. Because the threads 7, 9 lare in loose engagement, an axial force may be applied to the closure to snap the lip 20 past the shoulder 24, whereupon the application of torque tothe closure will then tig-hten threads '7, 9 and seal the rim 8 against the liner 14. During threading of the closure 1 on neck 10, the chuck or other device used for this purpose must grip both the skirt 17 and the portion of the closure thereabove to rotate the two parts as a unit. Otherwise the engagement of the lip 20 with the bead 22 will tend to impede the movement of the skirt 17 with the result that the torque will .rupture the bridges 19. The upper portion of the skirt 17 may have a radial enlargement or flange 37 at which it may be gripped.
The closure must be designed for the tolerances in cap molding as well as those in the manufacture of the container. Commercial glass bottles are made to certain tolerances recognized by glass container manufacturers. The -diameter of the lip 20, the diameter of the bead 22, and the wall thickness of the skirt 17 must be such, throughout the entire range of tolerances of the closure and container, that the skirt 17 flexes radially outwardly within its elastic limits to allow the lip 20 to pass over the bead 22, without causing the skirt 17 to crack. In addition there must be, within these tolerances, sufficient radial overlap between the lip 20 and shoulder 24 to cause the bead 22 to retain the lip 20 when the closure is Unthreaded `and has a torque applied thereto that is several times the torque required to unscrew the closure. Finally, the position of the lip 20 relative to the bridges 19 must be such that the lip 20 will be able to pass over and beyond the bead 22, leaving the gap 26, on a container in which distance from the shoulder 24 to the rim 8 is of maximum tolerance and the distance from the wall 4 to the lip 20 is of minimum tolerance.
In unthreading the closure from the neck 10, the initial torque loosens the engaged threads 7, 9. Once loosened, the continued torque is negligible for a small fraction of a revolution, say twenty to thirty degrees, whereupon the lip 20 engages the bead shoulder 24. Upon further unthreading, the bead 22 retains the lip 20 and inhibits axial movement of the skirt 17, and the applied torque on the closure causes the bridges 19 to rupture. Thus, the torque used to break the bridges is applied after the initial `or thread-loosening torque rather than simultaneously therewith. The severed skirt 17 drops downwardly onto the container below the lead 22, thereby indicating that the closure has been wholly or partially Unthreaded from the neck 10. The bridges 19 will tend to rupture at their smallest cr-oss sections 19a so that the break is clean and free of sharp edges at the end 13.
A modified form of closure is shown in FIGS. 9 and l0. Here the skirt 17 may be longitudinally slit as at 39 in one or more places from the lip 20 up to the flange 37.
4 This facilitates exing of the skirt 17 as the lip 20- snaps over the bead 22.
In the form of the invention shown in FIG. 11 the skirt 17 is longitudinally slit in two places which are diametrically opposed. One such slit is shown at 41, and it will be seen that the slit 41 extends completely through the skirt t-o divide the same into two l degree skirt sections 17a, 17b. Each skirt section is suspended from the wall end 18 by a number of the bridges 19. When the bridges 19 are cracked upon unthreading ofthe closure from the neck 10, the two separated skirt sections 17a, 17b will either fall away from the container or may be readily slipped away therefrom.
Glass bottles as now manufactured on automatic machines are subject to small dimensional deviations. On a run of bottles the distance between the surface 8 and the surface 24 will vary somewhat. Plastic and molded caps can be made on automatic machines to a much closer tolerance. The vertical gap 26 of FIG. 3 should preferably be within 0.015 inch and 0.035 inch to prevent leakage between the rim 8 and liner 14 when the cap is unscrewed as far as possible without fracturing the bridges 19. This distance should not be more than twice the mini-mum horizontal distance between Vthe bottle and the bottom of the cap as measured at 45 or 45', whichever is the smaller, to inhibit cocking of the cap when it has been slightly loosened. The numeral 45 is the minimum distance between the cylindrical cap skirt wall 25a and the nearest part of the bead 22, while 45 is the di'stance between the surface 21 of the bottle and the nearest portion of the annular lip 20, in both instances when the cap is in its sealing position illustrated in FIG. 3. This ratio (not more than 2 to 1) is of importance in many instances.
In compliance with the requirements `of the patent statutes I have herein shown and described a preferred embodiment of the invention. It is, however, to be understood that the invention is not limited to the precise construction herein shown, the same being merely illustrative of the principles of the invention.
What is considered new and sought to be secured by Letters Patent is:
1. In combination with a container having a threaded neck, a tamper-indicating closure comprising a body having an annular threaded wall for threading over said threaded neck, said container having a bead adjacent to the thread, and la skirt at an end of said wall and being integrally connected thereto by means forming a rupturaible zone of weakness, said skirt having a lip spaced from said means and projecting radially inwardly toward the axis of said threaded wall, the spacing from said means and the radial extent of projection of the lip being such that when the cl-osure is in its fully closed position on the container neck, the lip will be axially spaced from the bead and will have a radial overlap therewith and with the skirt being sufficiently yieldable within its elastic limits to enable the lip to pass over the bead when the closure is threaded onto the neck to the `fully closed position, a Ipar-tial unscrewing of the closure causing the lip to engage the bead and be retained thereby and further unscrewing of the closure causing rupture of the body at said zone of weakness.
2. A combination according to claim 1 in which the zone of weakness is formed by bridges of the `body material that are spaced circumferentially about the skirt.
3. A combination according to :claim 1 in which the skirt has at least one longitudinal slit that extends from the lip partially over the length of the skirt to enhance the flexibility thereof.
4. A combination according to claim 2 in which the skirt has a plurality of circumferentially spaced slits that are located between bridges and extend for lthe full length of the skirt to form circumferentially spaced skirt segments each of which is joined to said annular Wall by at least one bridge.
5. A combination according to claim 1 in which the cross sectional area of the zone of weakness adjacent to the annular Wall is greater than the cross sectional area adjacent to the skirt.
6. In combination with a container having a member that forms an opening into the container, a tamper-indieating closure member, cooperating means on said members for mounting the closure member on the container member and removing `the closure `member therefrom =by rotational `and axial movement of one member relative to the other member, said closure member having a wall disposed a'bout said container member, a skirt connected to said Wall 'by means forming a rupturable zone of Weakness, said skirt having a lip that radially overlaps and is axially spaced from a part of the container that is between said lip and said zone of weakness and with the radial overlap `causing sufficient axial interference to prevent removal ofthe closure member from said container member without rupturing said Zone of weakness, said skirt being suiciently yieldable within its elastic limits to enable the lip to pass over said container part when the closure member is mounted onto said container member, an initial rotational and axial movement of one member relative to the other member causing said lip and said container part to abut and thereby inhibit axial movement of the skirt, and further rotational and axial movement of one member relative to the other member causing the closure to rupture at said zone of weakness.
7. A combination according to claim 6 in which said initial rotational movement is a fraction of a revolution.
8. A combination according to claim 6 in which said axial spacing is not more than -twice the minimum radial distance between the skirt and the adjacent surface of the container.
9. A combination according to claim 6 including means forming a seal across said opening when the closure is in closed position on the container, said axial spacing being such that the seal prevents leakage of contents from the container when the closure and container are axially shifted relative to one another as far as possible wit-hout rupturing said zone of weakness.
10. In combination with a container having a threaded neck that forms an opening into the container, a radially outwardly projecting bead that is axially spaced from the thread, the bead having a shoulder that is presented in a generally axial direction away from the opening and with the amount of radial projection of the bead decreasing from said shoulder in a direction towards said opening, a tamper-indicating cl-osure threaded over said neck, said closure including a one-piece body member having an annular wall disposed about said neck and a skirt integrally connected to an end of said wall that is remote from said opening by body member material that forms a rupturable zone of weakness, said skirt having a radially inwardly projecting lip radially overlapping and axially spaced from said shoulder and with `the shoulder being axially between the lip and said opening, the radial overtlapl causing suicient axial interference between the lip and skirt to prevent unthreading removal of the closure from the neck without rupturing said zone of weakness, said skirt Ibeing suiciently yieldable within its elastic limits to enable the lip to pass over said bead when the closure is threaded onto said neck, an initial unthreading of the closure causing said lip to abut said shoulder and thereby inhibit axial movement ofthe skirt, and further unthreading of the closure causing the closure to rupture at said zone of weakness.
11. A combination according to claim 10 in which the zone of weakness is formed by spaced bridges of the body member material.
12. A combination according to claim 1t) in which the skirt has at least one longitudinal slit that extends from the lip partially over the length of the skirt to enhance the flexing thereof as the lip passes over the bead during mounting of the closure onto the container.
13. A combination according to claim 10 in which the skirt is circumiferentially slit from the lip to the zone of weakness in such manner that after rupture of said Zone of weakness and separation of the skirt from said annular wall, the skirt may be separated from the container.
1d. A combination according to claim 10 in which the cross sectional area of the zone of weakness adjacent to the annular wall is greater than the cross sectional area adjacent to the skirt.
References Cited UNITED STATES PATENTS 2,162,712 6/1939 Hamberger 215-42 2,367,317 1/1945 Thomas 215-42 X 3,259,233 7/ 1966 Beeman 220-27 JOSEPH R. LECLAIR, Primary Examiner. D. F. NORTON, Assistant Examiner.