US3252446A - Friction closure - Google Patents

Description

May 24, 1966 FIG. I

R. F. BATEMAN FRICTION CLOSURE Filed Aug. 15, 1964 INVENTOR ROBERT F. BATEMAN ATTORNEYS United States Patent 3,252,446 FRICTION CLOSURE Robert F. Bateman, Woonsocket, R.I., assignor to The Carters Ink Company, Cambridge, Mass, a corporation of Massachusetts 4 Filed Aug. 13, 1964, Ser. No. 389,328 2 Claims. (Cl. 120-4101) This invention relates generally to closure constructions and more particularly to the construction of closures employing frictional engagement as the operating principle thereof.

With the growing widespread use of new materials, such as plastics, and the current trend toward greater sophistication in packaging, various new closure designs have been produced to satisfy the aesthetic and practical requirements of contemporary commerce. Whereas at an earlier time almost all containers to which removable caps were fitted employed a screw-threaded closure construction with cooperating threads located on the container neck and the cap, numerous different constructions are currently employed. Where the container is to hold a fluid, a dispensing closure is often permanently fitted to the container body and includes a closa'ble aperture through which the contents may be dispensed as desired.

In other instances, typically with respect to writing in: struments, it is necessary to provide a totally removable cap which, when removed, exposes the writing point for use and which, when in place, both protects the Writing point and retains any possible writing fluid which may leak from the body of the container past or through the writing point.

For many years, almost all pens and similar drawing instruments were provided with screw-threaded caps. As new, more economical construction materials were employed for the writing instrument bodies and caps, it was also desired to eliminate the screw-thread closures. To this end, many writing instruments have for some time been provided with a type of friction closure which typically employs a cap having a slightly greater diameter than the body of the writing instrument over which it is fitted. The body, or the cap, is usually provided with some compressible means which frictionally engages the other member and retains the cap upon the body of the writing instrument. Flat springs mounted within the cap and resilient O-rings mounted about the body are commonplace contemporary constructions.

An even more efficient and less expensive frictional closure which is particularly adapted for use with writing instruments and the like, employs a pair of generally mating nesting surfaces, one of which is positioned about the exterior of the container body and the other of which forms an interior wall on the cap. The cap is engaged by nesting the pair of surfaces which have substantially identical diameters. Containers employing this closure construction are substantially less expensive to manufacture since no additional parts, springs, O-rings and the like are required. The construction is also relatively easy to use since the container is securely closed, at least in theory, simply by inserting the cap over the neck ofthe container and pushing it thereon as far as it will go. Despite the attractiveness of this construction, it has not met with substantial acceptance because of a severe limitation with respect to the amount of frictional engagement possible between the container and its cap. The conventional container having an elongated neck over which the friction cap is to be inserted may be securely closed by frictional engagement of the cap with the neck at only a limited portion of the neck area. area of frictional engagement between the nesting surfaces is located adjacent the base of the neck surface;

The

Conventionally, the Walls of the neck surface converge from the common diameter more rapidly than those of the cap thereby defining the lower portions of both the cap and the neck as the area of frictional engagement. The height of this area along the principal axis of the neck and cap need only be sufficient to insure that the frictional engagement will not be destroyed and the cap dislodged by accident. At the same time, however, it is necessary that the area of frictional engagement be small enough that the cap may 'be removed relatively easily by pulling it off of the neck of the container. Substantial difiiculty has been encountered in designing a frictional engagement closure which satisfactorily satisfies both the requirement of secure seating of the cap and that of easy removal. The cap has either been nested so strongly that the frictional engagement is extremely difficult to overcome, or alternatively, the area of frictional engagement has been so small that the cap may he accidentally dislodged or may fail to engage at all after a period of use.

It is, accordingly, a major object of this invention to construct a friction closure which includes sufficient frictional area to securely maintain the parts in engaged relation while permitting easy disengagement thereof when desired.

It is a further object of this invention to construct a friction closure which may be easily and inexpensively manufactured and will be suitable for use with relatively small containers as for example writing instruments and the like.

In the construction of a preferred embodiment of the invention the writing instrument employs a closure having a removable cap which is held "by frictional engagement between its inner surface and the outer surface of a neck on the body of the instrument. The area of frictional engagement between these nesting surfaces is of sufficient size that substantial difficulty is encountered in overcoming the coefficient of friction between the surfaces to dislodge the cap from the writing instrument. In order to provide easy disengagement of the cap when desired, a plurality of cooperating camming surfaces are formed on the cap and the instrument body to cooperate with each other along the line of closure. When it is desired to remove the cap from the closure it is only necessary to rotate the cap about its principal axis in either direction, thereby more easily overcoming the frictional engagement between the parts, which rotation is translated through the cooperating camming surfaces positioned about the line of closure into displacement of the cap longitudinally from the writing instrument.

It is a feature of the invention that the friction bond between the nested cap and container is initially overcome by relative rotary movement therebetween following which the cap is displaced longitudinally from the container neck.

It is a further feature of the invention that a substantial area of frictional engagement may be employed between the cap and the container to insure that the cap may not be accidentally dislodged and further to insure that normal distortion of the cap through use will not destroy the area of frictional engagement.

These and other objects and features of the invention will be more readily understood and appreciated from the following detailed description of a preferred embodiment thereof selected for purposes of illustration and shown in the accompanying drawings, in which:

FIG. 1 is a view in side elevation of a container cap "constructed according to the invention;

FIG. 2 is a view in side elevation of a container constructed to receive the cap of FIG. 1;

FIG. 3 is a section taken on the line 33 of FIG. 1;

FIG. 4 is a section taken on the line 4-4 of FIG. 2;

FIG. 5 is a view in side elevation of thecap of FIG. 1 and the container body of FIG. 2 in nested, engaged relation; and

FIG. 6 is a view in side elevation showing the cap and body of FIG. 5 during disengagement thereof.

In FIGS. 1 and 2 a container body 10 is shown. At the top of the body 10 is a frusto-conical shank or neck 12 from which extends a marking felt 14; and forming, in the preferred embodiment, the body of a generally cylindrical felt tip marker. The body 10 is normally filled with marking fluid which is dispensed by the felt 14.

A cap 16 is provided for engagement on the body 10. The cap 16 includes an internal frusto-conical bore 18 into which the neck 12 of the body 10 may be nested. The exterior configuration of the body 10 and the cap 16 is a matter of design only and forms no portion of this invention.

In FIG. 5 an angular line of closure 20 is shown between the body 10 and the cap 16 when they are fully nested. When the cap 16 is fully engaged on the body 10, the exterior surface of the neck 12 is in frictional engagement with a portion of the bore 18. The area of frictional contact is indicated generally at 22 in FIGS. 1 and 2 respectively. The extent to which the frictional contact area 22 extends upwardly along the neck 12 and upwardly from the open end of the bore 18 will depend in each instance upon the particular application. The proportions shown in FIGS. 1 and 2 are, however, typical. The extent of the frictional contact area 22 is determined by the selection of angles for the nesting surfaces on the neck 12 and the bore 18. Generally speaking, the neck 12 has an angle included between its base and side wall which is smaller than the angle between the base and side wall of the bore 18. The two angles are initially selected of sufiicient size, however, that the nesting surfaces are in frictional contact through an area of sufficient size to provide a secure fit.

In order to disengage the cap 16 from the body 10 a plurality of camming surfaces 24 are provided on the body 10 about the base of the neck 12. The camming surfaces 24 are contiguous spiral segments alternately sloping in opposite axial directions and form a plurality of generally angular upstanding shoulders 26 about the base of the neck 12. The height of the camming surfaces 24 and hence of the shoulders 26 is substantially the same as the height of the area of frictional engagement of the neck 12.

Depending camming surfaces 28 are formed about the base of the cap 16 at the entrance to the bore 18 to cooperate with the camming surfaces 24 on the body 10. The camming surfaces 28 on the cap 16 likewise form a plurality of generally angular depending shoulders 30 positioned about the base of the cap 16. The camming surfaces 28 on the cap 16 mate with the camming surfaces 24 on the body 10 when the cap 16 is inserted over the neck 12 and abut along the angular line of closure 20.

FIG. 6 shows the cooperation of the camming surfaces 24 and 28 to cause the depending shoulders 30 on the cap 16 to ride upwardly upon the upstanding shoulders 26 on the body 10 during relative rotation of the cap 16 with respect to the body 10. It will be noted that since the height of the shoulders 26 and the shoulders 30 is substantially the same as the height of the area of the frictional engagement 22 it is possible to free the cap 16 for easy removal by displacing it axially along the neck 12 a distance equal to the height of either the shoulder 26 or the shoulder 30. Because of the extensive area of frictional engagement 22, as desired to maintain the cap securely in place, it would, however, be extremely difficult to withdraw the cap from the container by simply exerting an axial separating force.

As is well known, the effort required to overcome frictional engagement in the area 22 is substantially greater when a force is applied to separate the surfaces axially than when a force is applied to cause relative rotation between the two parts. Rotation alone will not, however, dislodge the cap 16 from the neck 12 and translation of the rotary motion to axial motion has heretofore required a cessation of rotary motion thereby re-establishing the frictional bond between the cap 16 and the neck 12.

It will also be noted that a mechanical advantage is achieved in disengaging the cap from the neck since the outside diameter of the cap, which is grasped by the user, is substantially greater than the interior diameter thereof which defines the area of frictional engagement.

By providing the novel camming surfaces 24 and 28 it is possible to translate relative rotary motion between the cap 16 and the neck 12 gradually and without cessation into axial motion tending to displace the two parts. Hence, once the frictional bond is destroyed by relative rotation the cap 16 may be removed without re-establishing the bond through the operation of the co-operating camming surfacescausing the shoulders 26 and 30 to ride against each other thereby displacing the cap 16 axially along the neck 12 beyond the area of frictional engagement 22.

It will thus be noted that through the operation of the camming surfaces and the shoulders of the invention it is possible to first overcome the frictional engagement of two members having partially mating nesting surfaces by the application of a relative rotary motion which is translated through the operation of the camming surfaces and the shoulders into an axially displacing motion. With the construction of this invention it is now possible to provide a substantially greater area of frictional engagement between the nesting surfaces providing a substantially better friction seal thereby permitting the use of this less expensive, more easily fabricated construction for a plurality of containers the caps of which it is important should not he accidentally dislodged.

While in the illustrated preferred embodiment three cooperating shoulders and their adjacent camming surfaces are shown continuously about the line of closure of the container, it will be understood that more or less cooperating shoulders may be employed. However, although a single shoulder and the adjacent pair of camming surfaces on each member-will suffice, seating of the cap 16 upon the body 10 is however facilitated by a continuous array of shoulders and camming surfaces. Since each shoulder is formed of a pair of camming surfaces it will be understood that there will always be an even number of camming surfaces.

Having thus disclosed and illustrated a preferred embodiment of the invention it is my intention to claim all changes and modifications thereof.

What I claim as new and desire -to secure by Letters Patent of the United States is: v

1. In a closable container comprising a body having an opening terminating in a neck and a closure cap having a bore nestable with said neck with at least a portion of said neck being in frictional engagement with a corresponding portion of said bore;

means facilitating the removal of said cap comprising (a) an even number of equal contiguous spiral segments alternately sloping in opposite axial directions to form a series of angular upstanding shoulders on said body and completely surrounding said neck, and

(b) corresponding equal contiguous spiral segments alternately sloping in opposite axial directions to form a corresponding series of angular upstanding shoulders on said closure cap in face to face sliding engagement with the segments on said body whereby twisting said closure cap in either direction results in a camming action between said segments effective to move said cap away from said body.

2. In a closure for a writing instrument which includes a body and a generally frusto-conical neck terminating in a writing tip and a cap having a bore receiving said neck in frictional engagement therewith:

means facilitating the removal of said cap comprising a) an even number of equal contiguous spiral segments alternately sloping in opposite axial directions to form a series of angular upstanding shoulders on said body and completely surrounding said neck, and (b) corresponding equal contiguous spiral segments alternately sloping in opposite axial directions to form a corresponding series of angular upstanding shoulders on said Cap in face to face sliding engagement with the segments on said body,

References Cited by the Examiner UNITED STATES PATENTS Wing 12042 McKelvy 21546 Hoffmann 2i15-46 Ruetz 215-46 JOSEPH R. LECLAIR, Primary Examiner.

R. PESHOCK, Assistant Examiner.

Claims (1)

1. 2. IN A CLOSURE FOR A WRITING INSTRUMENT WHICH INCLUDES A BODY AND A GENERALLY FRUSTO-CONICAL NECK TERMINATING IN A WRITING TIP AND A CAP HAVING A BORE RECEIVING SAID NECK IN FRICTIONAL ENGAGEMENT THEREWITH; MEANS FACILITATING THE REMOVAL OF SAID CAP COMPRISING (A) AN EVEN NUMBER OF EQUAL CONTIGUOUS SPIRAL SEGMENTS ALTERNATELY SLOPPING IN OPPOSITE AXIAL DIRECTIONS TO FORM A SERIES OF ANGULAR UPSTANDING SHOULDERS ON SAID BODY AND COMPLETELY SURROUNDING SAID NECK, AND (B) CORRESPONDING EQUAL CONTIGUOUS SPIRAL SEGMENTS ALTENATELY SLOPPING IN OPPOSITE AXIAL DIRECTIONS TO FORM A CORRESPONDING SERIES OF ANGULAR UPSTANDING SHOULDERS ON SAID CAP IN FACE TO FACE SLIDING ENGAGEMENT WITH THE SEGMENTS ON SAID BODY, WHEREBY TWISTING SAID CAP IN EITHER DIRECTION RESULTS IN A CAMMING ACTION BETWEEN SAID SEGMENTS EFFECTIVE TO MOVE SAID CAP AWAY FROM SAID BODY.

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