Tamper indicating screw cap

A threaded one piece closure having a tamper indicating ring attached to the lower end of the cap skirt by shear webs which fracture upon the initial opening of the closure leaving the detached ring on the container indicating the initial opening or tampering. The inner surface of the ring has a retaining bead which engages an annular flange on the container which restrains movement of the ring in the opening process. Cooperating drive means on the cap skirt and ring allow initial closure application to the container without fracture of the shear webs.

This invention relates to tamper indicating closures and more specifically 
to closures in which a cap and ring are formed as a single piece and 
separate from each other upon an attempt to open the container, the 
separated ring giving evidence that the container has been opened or that 
an attempt has been made to open it. 
Tamper indicating closures of the type having a separable ring which 
remains with the container upon opening of the container to indicate 
tampering by way of separation of the ring and the remainder of the 
closure have been provided in various forms. In one form, the closure must 
be applied in at least two steps, one of which requires the application of 
heat after the closure has been applied to a filled container to deform a 
skirt portion to lock into position relative to the container. In another 
form of one-piece tamper indicating closure, the closure and separable 
ring must be axially aligned to transmit capping or closing forces to 
prevent premature separation of the ring and the closure. Such 
constructions, however, are extremely difficult to mold and require 
complex molds and molding procedures. Still other of such one-piece tamper 
indicating closures require modification of the container to insure proper 
separation of the tamper indicating ring and the remainder of the closure. 
In accordance with the present invention, a one-piece tamper indicating 
closure has been provided in which the closure can be applied to a 
container in a single step operation and in which the closure is made up 
of a cap and a separable ring in which the ring is concentric with the cap 
so that it is radially spaced outwardly therefrom. The cap and ring are 
provided with driving and driven surfaces which engage each other to 
transmit both circumferential and axial loads preventing premature 
breakage and separation of the ring from the remainder of the closure. 
Such a construction permits more simplified molding techniques and molds 
while at the same time accomplishing all of the advantages of a tamper 
indicating closure in which a ring separates from the cap portion and 
remains with the container to indicate that there has been prior opening 
of the container.

A tamper indicating closure embodying the invention is designated generally 
at 10 is formed in a single piece and is intended for use on a container 
12 having external threads 14 on a neck 16 which is formed with an annular 
flange 18 disposed below the external threads 14. 
The closure 10 includes an upper cap portion 20 having an end wall 22 and a 
cylindrical side wall 24 with an internally threaded portion having 
internal threads 26 engageable with the external threads 14 to hold the 
closure 10 in closed position on the container 12. The closure 10 also 
includes a ring element 30 which is disposed concentrically with the 
cylindrical skirt 24 and is disposed in slightly radially outwardly spaced 
relation relative thereto. The ring element 30 is joined to the cap 
portion 20 by a plurality of circumferentially spaced web elements 32. As 
indicated in FIG. 1, eight equally spaced shear webs 32 can be used. The 
ring element 30 is also provided with a radially inwardly projecting 
annular bead 34 engageable with the lower surface 36 of the annular flange 
18. 
The cap portion 20 and ring element 30 are molded as an integral unit in 
one piece and the problem to be solved is the application of the closure 
10 to the container 12 without fracturing the web elements 32 prematurely. 
For this purpose, the lower exterior surface 36 of the cylindrical skirt 
24 is provided with drive lugs 38 which in the as-molded condition of the 
tamper indicating closure 10 are slightly spaced from driven lugs 40 
formed on the top surface of the ring element 30. A load transmitting land 
means 42 is formed on the ring element 30 between the drive and driven 
lugs 38 and 40. The underside of the drive lug 39 forms additional load 
transmitting land means 44 which during application of the tamper 
indicating closure 10 to the container 12 come into contact with the land 
means 42. As indicated in FIG. 1, eight equally spaced pairs of 
cooperating drive and driven lugs and cooperating land means can be 
located between adjacent shear webs. 
The radial spacing between the concentrically disposed ring element 30 and 
cylindrical skirt 24 defines an open area 28 between adjacent shear webs 
32 into which area drive lug 38 extends radially outward from lower skirt 
surface 36 and driven lug 40 extends radially inward from the top of ring 
30 for engagement with each other in a vertical plane. Horizontally 
disposed land means 42 is contiguous and extends inward with driven lug 40 
from the top of ring 30. Horizontally disposed land means 44 is formed on 
the underside of drive lug 38 for cooperation with land means 42. 
Upon application of the tamper indicating closure 10 to the container 12, 
the cap portion 20 is held in capping equipment which is capable of 
applying a rotational or closing torque while at the same time moving the 
closure 10 downwardly realtive to the container 12. During such a capping 
operation, the lower surface of the bead 34 will come into engagement with 
the top surface of the annular flange 18 to offer frictional resistance to 
rotation of the ring element 30 relative to the container 12. This causes 
relative rotation between the ring element 30 and the cap portion 20 which 
deflects the web elements 32 (see FIG. 4) sufficiently so that the drive 
lugs 38 come into face-to-face engagement with the driven lugs 40. 
Similarly, the land means 44 at the underside of the drive lug 38 will 
come into alignment with the land means 42 on the ring element 30. 
Subsequent application of capping torque to the cap element 20 causes 
engagement of the external container threads 14 with internal container 
threads 26 causing axial downward movement of the tamper indicating 
closure 10 relative to the container 12. During such rotational and axial 
movement, the ring element 30 remains stationary relative to the cap 
portion 20 with the drive and driven lugs 38 and 40 and the land means 42, 
44 in engagement with each other. This holds the ring element 30 
stationary relative to the cap portion so that both rotational and axial 
loads can be transmitted without subjecting the web elements 32 to 
additional loads which might otherwise fracture them. During the 
application of the rotational and axial forces, the bead 34 is forced over 
the annular flange 18 so that the bead snaps into position and locks the 
closure 10 relative to the container 12. 
In order to open the container 12, it is necessary to remove the cap 
portion 20 which can only be accomplished by separating the ring element 
30 and the cap portion 20. Such separation requires severing of the web 
elements 32. This is accomplished by unscrewing the cap portion 20 
relative to the container 12. This brings the top surface of the bead 34 
into tight engagement with the underside of the annular flange 18 and as 
the unthreading action continues, the web elements 32 are deflected 
sufficiently to fracture them so that the cap portion 20 can be completely 
unthreaded from the container 12 but the ring element 30 is retained by 
the inner action of the bead 34 and flange 18. Such separation of the ring 
30 from the cap portion 20 gives an indication that there has been a prior 
opening of the container 12 and therefore, possible tampering. 
After first opening of the container 12, the cap portion 20 can be 
reapplied to the container 12 to close the container 12 against spillage 
of its contents during which time the ring element 30 is retained in 
position on the container 12, not only to prevent litering but also to 
give the indication of tampering or initial opening.