US 3455478 A
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i y 15, 1969 M. R. FIELDS L TAMPER-INDICATING CLOSURE Filed July 21, 1967 0 IT .5 2 E7.
. S. 2 3 4 s v 4 4 Q 5 M6 Mum l l l 5 T A A Fm F W m F w w in R L I N m mmm. 2 5 B L M Q MZG v M 9 7 a .1 M H II i H l| 5 H9 3,455,478 TAMPER-INDICATING CLOSURE Mack R. Fields, Lighthouse Point, and Zbislaw M. Roehr,
Miami, Fla., and Glenn L. Beall, Wiltlwood, 11]., assignors to Roehr Metals & Plastics Company, a limited partnership of Connecticut Filed July 21, 1967, Ser. No. 655,225 Int. Cl. B65d 55/02, 41/34 U.S. Cl. 215-7 8 Claims ABSTRACT OF THE DISCLOSURE A screw-threaded plastic cap has a tamper-indicating skirt that is joined to the cap sidewall by frangible bridges of cap plastic. The bridges are disposed so that they are placed in compression to resist rupture caused by the torque due to frictional drag between the skirt and a container head when the closure is mounted in place. Upon unscrewing the closure, the engagement of the bead and skirt cause the bridges to be placed in tension and easily ruptures at their weakest points, which are in recesses at the bottom of the cap sidewall.
This invention relates to improvements in tam er-indicating closures for bottles and like containers.
The tamper-indicating closure of the type with which the present invention is concerned comprises an annular body that may be screw-threaded over a container neck. A resilient skirt is integrally joined to the lower end of the body by a frangible zone of weakness that may be formed by thin sections or bridges of the closure material. The skirt is so constructed that when the closure is in its closed position, the skirt has a part that radially overlaps with the bead or transfer ring of the container such that upon unscrewing of the closure from the container for the first time, the engagement of the bead and skirt results in retention of the skirt. The unscrewing torque thus causes rupture of the zone of weakness, which indicates that the closure has been removed or that there has been tampering with the same.
Because the skirt and container bead are dimensioned to have an overlap, it is necessary, when the closure is capped onto the container neck, that the skirt resiliently expand in order that its interfering part may pass over the bead. Unless the skirt and cap body are held together by a capping chuck that grips both, the frictional drag resulting from the engagement of the aforesaid skirt part and bottle bead may cause suflicient torque to be applied to the skirt to rupture the zone of weakness.
It is an object of this invention to provide a tamperindicating closure of the type stated in which the zone of weakness is so constructed as to have a rupture strength to resist torque caused by the frictional drag between the skirt and container bead when the closure is being threaded onto the container, but which has an insufiicient strength to resist an equal or even lesser torque that will be applied in the opposite direction by a person unscrewing the closure. The capping chuck may thus be of a type used for ordinary nontamper-indicating screw-threaded closures since the chuck need not be designed for gripping the tamper-indicating skirt.
It is a further and more specific object of this invention to provide a closure of the type stated in which the bridges of material forming the zone of weakness are at acute angles to the adjacent edges of the cap body wall and skirt such that in screw-threading the closure onto the container neck, the frangible bridges will 'be placed in compression by the torque resulting from the frictional drag between the skirt and container bead. However, when torque is applied tending to remove the closure, the
nited States Patent ice 3,455,478 Patented July 15, 1969 bridges will be placed in tension. The bridges are Weaker in tension than in compression with the result that they will not break due to the torque encountered upon mounting the closure in place but will rupture upon application of a relatively lower unscrewing torque.
It is a still further object of this invention to provide a closure of the type stated in which the lower end of the cap body wall has recesses in which the tamper-indicating bridges are attached to said body wall. Each bridge is made weakest at the portion thereof that is in the recess so that upon rupture of the bridges at the weakest portions, the raw edges remaining on the cap body will lie in the recesses and will not project axially beyond the lower edge of the cap but will, in effect, be shielded thereby.
The attainment of the above and further objects of this invention will be apparent from the following detailed description, reference being made to the accompanying drawing forming a part thereof.
In the drawing:
FIG. 1 is a sectional view taken along line 11 of FIG. 2, partially broken away and on an enlarged scale, and showing a tamper-indicating closure of this invention mounted on a container neck;
FIG. 2 is a fragmentary sectional view taken along line 22 of FIG. 1;
FIG. 3 is an enlargement of the broken-away portion of FIG. 1 showing the closure in the region of one of the frangible bridges;
FIG. 4 is a fragmentary sectional view taken along line 44 of FIG. 3;
FIG. 5 is a fragmentary sectional view, on an enlarged scale, taken along line 55 of FIG. 1, and
FIG. 6 is a fragmentary elevational view of a portion of FIG. 3 and showing a part of the lower end of the cap side wall after rupture of the frangible tamper-indicating bridges.
Referring now in more detail and by reference char acters to the drawing, which illustrates a preferred embodiment of this invention, 1 designates a closure comprising a cap body 2 which may be a one-piece molded plastic member. Polyethylene or a commercial grade of high impact strength polystyrene may be used for molding the cap body 2. The body 2 includes an end wall 3 and an annular sidewall 5 which is externally knurled to facilitate gripping thereof. Internally thereof, the sidewall 5 is molded with a thread 6 for threaded engagement with the external thread 7 that is formed on the neck 9 of a container 10, for instance a glass bottle. Adjacent to the thread 6 the sidewall 5 is molded with an inwardly projecting annular lip 11 which cooperates with the end wall 3 to provide a groove for receiving a sealing disc 13 which bears against the rim of the neck 9 to seal the opening thereat when the closure is in closed position on the neck 9.
Adjacent to the lower or free edge 14 of the sidewall 5 is an axially extending annular skirt 15 that is joined to the sidewall 5 by circumferentially spaced frangible bridges 17 of the plastic material out of which the'cap is molded. In the present form of the invention, there are six equally spaced identical bridges 17.
The sidewall 5 is formed with circumferentially spaced recesses 18 which open at the lower edge 14. One such recess 18 is shown in FIGS. 1, 3, 4 and 6, it being understood that the others are identical. The upper end 19 of the bridge 17 is joined to the sidewall 5 in the recess 18 and is, therefore, axially upwardly from the lower edge 14. The lower end 21 of the bridge 17 is joined to the upper edge 22 of the skirt 15. It will be noted that the bridges are disposed at an acute angle to the edges 14, 22, since the bridge junctures at 19, 21 are circumferentially offset. In a typical cap of the nominal 28 mm. size, this angle may be of the order of thirty degrees. The angular disposition of the bridge 17 is such that upon threading of cap 1 onto the' container neck 9, the juncture at 21 will be the leading end of the bridge 17, as respects the direction of rotation of the cap 1, and for purposes presently more fully appearing. The bridges 17 are thinher in cross section than the sidewall 5 and are also tapered so that they are thinnest and weakest at their upper end junctures 19, which are in the recesses 18.
At its lower end, the skirt 15 is molded with a radially inwardly directed annular lip 23 which, when the cap is in closed position on the container neck 9, radially overlaps an annular head 25 that is integrally formed on and projects radially outwardly from the neck 9 and is axially spaced from the thread 7. This bead 25 progressively increases in diameter axially away from the neck thread to a shoulder 26 thereon and below which the lip 23 is located. A small gap 27 may be present between the shoulder 26 and lip 23 for reasons pointed out in the Patent No. 3,329,295 of Mack P. Fields, one of the joint inventors herein, and to which reference may be had. If the container 10 is a glass bottle, the: bead 25 may be the so-called transfer ring used to handle the bottle during removal thereof from its mold.
In initially mounting the cap 1 onto the container 10, the cap is threaded onto the neck 9 until the lip 23 interferes with the bead 25 some place above the shoulder 26. Further rotation of the cap 1 will cause further axial movement thereof and, in turn, cause the skirt to fiex outwardly elastically as the lip 23 moves further and further along the bead 25. Finally, the lip 23 snaps past the shoulder 26 and continued torque on the cap seals the disc 13 against the rim of the neck 9.
The cap 1 may be initially mounted onto the container by conventional capping machinery that includes a chuck for gripping the cap body 2. When the lip 23 of the rotating cap first engages the bead there will be a small frictional drag therebetween. This frictional drag will increase as the cap thereafter moves axially due to the fact that the part of the bead 25 that is engaged by the lip 23 is of progressively increasing diameter. The greatest drag will be just before the lip 23 passes over the peak diameter of the bead 25. This frictional drag causes a torque to be applied to the skirt 15 which is resisted by the bridges 17. Since the bridge junction 19 is on the cap wall 5 and this junction 19 is the trailing end of the bridge, the junction 19 tends to be relatively displaced slightly, within elastic limits, toward the junction 21, thus placing the bridges 17 in compression. The bridges should, therefore, be designed so that they will resist the maximum expected compressive forces. However, the plastic of the cap has a greater rupture strength in compression than in tension. Accordingly, when the bridges are designed to resist the torque that produces the maximum anticipated compression stresses, the bridges can be fractured with a lesser torque applied in the opposite direction and tending to unscrew the cap 1 from the neck 9. Thus, the construction and arrangement of the bridges 17 have the unique advantage in that they will not rupture during capping by conventional machinery, but yet will rupture by a relatively low unscrewing torque on the cap.
In unthreading the cap from the container neck 9, the initial unscrewing torque loosens the threads and rotation of the cap a fraction of a revolution results in engagement of the lip 23 with the shoulder 26. Further unthreading of the cap 1 causes the skirt 15 to-be retained by the bead 25 and results in tension being applied to the bridges 17. The bridges 17 will rupture at their weakest regions 19 and this rupture will result in a raw edge at each bridge, as shown at 19a in FIG. 6 with respect to one of the bridges. This raw edge 19a is within the recess 18, and therefore the bottom edge 14 of the wall 5 does not present a series of raw edges resulting from the broken bridges. The broken bridges 17 will indicate that the cap has been removed or loosened an amount sufiicient to break the seal at the disc 13. If the radial clearance between the skirt 15 and the bead 25 upwardly of the lip 23 is suflicient, the skirt 15 will drop downwardly onto the part of the bottle 10 below the bead 25.
The precise construction herein shown is merely illustrative of the principles of the invention. What is considered new and sought to be secured by Letters Patent 1. A tamper-indicating closure comprising a body with an annular wall having means for threaded engagement with a container neck, an arcuate skirt joined to an end of said wall by means comprising a bridge of material, said bridge being joined to an axially presented edge of said skirt that is adjacent to said wall and at a region thereof that is circumferentially offset from the region of juncture of the bridge and said wall, said bridge having a rupturable region and extending from the region of juncture with said wall to the region of juncture with said skirt edge along an axial path that is at an acute angle to said end and said edge to place said rupturable region in compression when the closure is threaded onto the container neck, said rupturable region having a greater resistance to rupture by compression than by tension.
2. A closure according to claim 1 in which said wall has a recess at said end, the juncture of the bridge and wall is in said recess, and said rupturable region is in said recess and is shielded by the part of the skirt that defines said recess upon rupture of said region.
3. A tamper-indicating closure comprising a body with an annular wall having means for threaded engagement with a container neck, an arcuate skirt joined to an end of said wall by means comprising a frangible bridge of material, the end of said wall having a recess and the junction of said bridge and said wall being in said recess, said bridge being Weakest at the part thereof that is in said recess and is shielded by the part of the skirt that defines said recess upon rupture of said bridge at said Weakest part.
4. A tamper-indicating closure in combination with a container having a member that forms an opening into the container, cooperating means on said member 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 about said container member, and a skirt connected to said wall by means forming a rupturable zone of weakness, said skirt and said container member having cooperating means for preventing removal of the closure member from the container member without rupturing said means forming the zone of weakness, said skirt and container member interfering when the closure member is being mounted on said container member and by said interference causing a torque to be applied to said skirt tending to twist it relative to said wall, said means forming the zone of weakness having a rupture strength sufficient to resist said torque but insufficient to resist a torque of equal magnitude tending to remove the closure member from the container member.
5. A structure according to claim 4 in which said means forming the Zone of weakness includes a bridge material that is placed under compression by said torque applied during mounting the closure member and is placed under tension by the torque tending to remove said closure member.
6. A structure according to claim 4 in which said means forming the zone of Weakness has circumferentially spaced bridges each joined to the skirt and wall, the juncture of each bridge and the wall being circumferentially offset from the juncture of the bridge and the skirt and with the juncture at said skirt being the leading end of the bridge when the closure member is mounted onto the container member.
7. A structure according to claim 5 in which the skirt is adjacent to an axially presented edge of said wall at one end thereof, said wall has recesses opening at said edge, each bridge projects into a recess and is joined to the wall in said recess, and each bridge having its Weakest portion in said recess.
8. A structure according to claim 4 in which the container member has a radially outwardly projecting bead and said skirt has a radially inwardly projecting lip, said head and lip causing said interference between the skirt and container member and also forming said secondmentioned cooperating means, said skirt being sufficiently yieldable within its elastic limits to enable said lip to pass over said head when the two members are assembled, and said means forming the Zone of weakness includes a bridge of closure material that is joined to said wall and skirt at circumferentially offset regions.
References Cited UNITED STATES PATENTS 3,162,329 12/1964 Gregory 22027 X 3,249,247 5/1966 Babiol 215-42 3,259,233 7/1966 Beeman 215-42 10 GEORGE E. LOWRANCE, Primary Examiner US. Cl. X.R. 215-42; 22027