GB1598650A

GB1598650A - Method and apparatus for fitting a closure to a container

Info

Publication number: GB1598650A
Application number: GB25812/78A
Authority: GB
Original assignee: Metal Box PLC
Current assignee: Crown Packaging UK Ltd
Priority date: 1978-05-31
Filing date: 1978-05-31
Publication date: 1981-09-23
Also published as: ZA792185B

Description

(54) METHOD AND APPARATUS FOR FITTING A CLOSURE TO A CONTAINER (71) We, METAL Box LIMITED, a British Company, of Queens House, Forbury Road, Reading, RGl 3JH, England, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to the fitting of closures on containers, and in particular to a manner of providing a container having an externally screw threaded outlet with a closure having a co-operating screw thread.

One known method of providing a container with a screw threaded closure involves first positioning the closure, which is initially in the form of an unthreaded cylindrical cap, onto the externally threaded opening or neck of a container, e.g. a bottle. The edge of a disc is pressed on the side of the cap, and the disc is rotated around the cap so as to exert pressure on those portions of the cap intermediate the outwardly projecting part of the thread on the neck. The pressure causes the cap to conform to the shape of the neck on which it is fitted, so that the cap is provided with an internal, helical ridge forming a thread co-operating with the thread on the neck.

This method is used on production lines.

A problem arises due to the fact that when the disc is pressed to form a thread the pressure developed occasionally causes a bottle to break, particularly if by accident no cap was fitted on to the neck of the bottle during an earlier stage in the process. Because of the high speeds presently found in production lines, a broken bottle and the consequent necessity of halting the process while the parts are removed from the apparatus, involves a significant reduction in the resulting output of the production line. This problem is particularly prevalent when, instead of aluminium caps, the cheaper alternative of tinplate caps is used, because of the greater pressures required to deform such caps.

Furthermore, aluminium caps have generally been used in the process described above because, although tinplate caps are cheaper, the threads on them could not be formed satisfactorily as their inherent resiliency caused "spring-back", resulting in loosefitting caps.

The invention, basically resides in using, instead of the disc, a helical member which is compressed radially to exert pressure on the closure only at those parts at which the thread is to be formed.

The helical member can be arranged so that it does not impose excessive forces on the bottles, so that the incidence of bottle breakage is substantially reduced. Also, by exerting equal pressures around the closure's circumference, the problems arising from "springback" can be substantially reduced or eliminated.

According to one aspect of the invention, a method of closing a container comprises positioning a generally cylindrical closure on an externally screw threaded outlet of the container, positioning the closure within a thread forming means having a helical engaging surface and compressing the forming means radially so that the engaging surface exerts pressure on the closure between the outwardly projecting portions of the thread on the container outlet, thereby to deform the closure to produce a co-operating thread thereon.

According to another aspect of the invention, apparatus for closing a container comprises a support carrying a thread forming means which has a helical engaging surface and which is arranged to receive therein an externally screw threaded container outlet on which a generally cylindrical closure has been fitted, means being provided to compress the thread forming means radially around the closure thereby to form thereon a thread co-operating with the thread on the outlet.

The term "radially" as used herein in relation to the direction in which the thread forming means is compressed, is intended to refer to a direction transverse to the helix axis of the engaging surface.

The thread forming means may be a helical member and may comprise a spring washer, the internal surface of which is the helical engaging surface. The pitch of the washer will be arranged to correspond with that of the external screw thread on the container to be closed, and the inner edge of the washer is preferably contoured so as to provide the thread on the closure with a desired cross-sectional configuration.

The invention also extends to a container fitted with a closure by means of the method described above.

Arrangements embodying the invention will now be described by way of example, with reference to the accompanying drawings, in which: Figure 1 is a section through a preferred embodiment of the apparatus of the invention, showing the apparatus in two separate positions; Figures 2A and 2B are respectively side and plan views of a component of the apparatus of Figure 1; Figure 3 is a perspective view of a helical forming member used in the apparatus of Figure 1; Figure 4 is a section through the helical forming member of Figure 3; Figure 5 is a vertical section through a further embodiment of an apparatus for closing containers in accordance with the invention; and Figure 6 is a vertical section through another embodiment of the apparatus of the invention.

Figure 1 shows a preferred embodiment of the apparatus of the invention. The apparatus 2 includes a main body 4 carried by an upwardly extending rod 6, which is movable vertically by means (not shown) to effect operation of the apparatus.

The main body 4 is generally in the form of a hollow cylinder having a closed upper end.

A generally cylindrical element 8 is vertically slidable within the main body 4. The element 8 comprises a hollow cylindrical portion 10 positioned coaxially within the body 4, and a cap retaining portion 12 which closes the lower end of the portion 10. The portion 12 has a lower end which is profiled as indicated at 14 so as closely to fit over a cap on a bottle presented to the apparatus.

A cylindrical sleeve 16 surrounds the cylindrical portion 10 and is made of a material which is adapted to ensure that there is little friction as the element 8 slides vertically within the main body 4. The extent of the sliding motion is limited by screws 18 which project inwardly to the interior of the main body 4 and through aligned apertures in the sleeve 16 and cylindrical portion 10 of the element 8.

The element 8 is biassed by a pair of coaxial coil springs 20 to its lower position as shown on the right of Figure 1.

Four arcuate segments 22 (see Figures 2A and 2B surround the lower end of the cap retaining portion 12. These segments 22, which are held together by a resilient retaining ring 24 for ease in assembly of the apparatus, together define a frusto-conical outer surface 26, which abuts against a corresponding surface 28 on the interior of the lower end of the main body 4. The segments each have an inwardly-projecting lip 30 which engages in an annular recess 32 surrounding the cap retaining portion 12, so as to retain the segments in position.

A spring washer 34 (see also Figure 3) is positioned within the segments 22 and under the cap retaining portion 12. The spring washer 34 is held in position by means of an inwardly-projecting lip 36 on the lower end of each of the segments 22. The inner edge 38 of the spring washer 34 has a profile as indicated in Figure 4.

With the apparatus in its normal position as shown on the right of Figure 1, a bottle having a cylindrical cap fitted over its neck is presented with the upper end of the cap abutting against the lower end of the cap retaining portion 12, and so that the spring washer 34 surrounds the cap.

The rod 6, and hence the main body 4, is then pushed downwardly to achieve the position shown on the left to Figure 1. This causes the portion 12 to press down on the cap, and the main body 4 to move with respect to the segments 22 so that the co-operating frusto-conical surfaces 26 and 28 on these members cause the segments to move inwardly. This in turn causes the spring washer 34 to be squeezed radially, thereby to deform the cap between the outwardly projecting parts of the thread on the bottle neck, and produce a co-operating inner thread on the cap.

Passages 40 are provided to connect the interior of the main body 4 with the exterior so that air can escape from the interior when the main body 4 is pushed downwardly, and the volume of air in the interior between the upper end of the main body 4 and the cap retaining portion 12 decreases.

As shown in Figure 3, the spring washer 34 may be provided with an outwardly extending protrusion 41, to be received in an upwardly extending groove (not shown) in the inner surface of one of the segments 22, to prevent rotation of the washer 34.

Various alternative means may be used to cause the spring washer to be compressed radially. For example, the ends of the washer may be pulled tangentially to cause the diameter of the washer to decrease.

Means are provided for ensuring that the bottle is presented to the apparatus 2 with the thread on its neck oriented within a pre determined range to ensure that the spring washer engages the cap at the correct position.

Figure 5 shows an alternative embodiment in which a main body 44 of the apparatus 42 is generally cylindrical and has a central bore 46 extending vertically therethrough. The bore 46 is divided into an upper and lower portion by an annular rim 48 the inner edge of which defines a hole 50.

A vertical rod 52 extends through the hole, and a nut 54 is screwed onto the upper end of the rod, which is threaded for this purpose, to act as a stop. The lower end of the rod 52 has an outwardly extending rim 56 from which a cylindrical flange 58 depends downwardly. A coil spring 60 surrounds the rod 52 and extends between the upper surface of the rim 56 and the lower surface of the rim 48. The rod 52 is thereby biased downwardly by the spring 60 but slidable upwardly through the hole 50 against the bias of the spring 60.

The lower end of the bore 46 is tapered outwardly as indicated at 62 to provide a frusto-conical surface.

A thread forming means in the form of a spring washer 64, which may be similar to the washer 34 of Figure 3, is positioned with its axis vertical and within the lower end of the bore 46, and retained therein by a removable annular member 66 fixed to the bottom of the main body 44.

In use of the apparatus a bottle such as that indicated at 68 having an externally threaded neck 70, is provided with a cylindrical cap 72 which is fitted over the neck 70.

The neck and cap are then located in the lower end of the bore 46, with the upper end of the cap engaging the lower end of the rod 52 within the cylindrical flange 58. The spring washer 64 is situated around the cap 72.

Means (not shown) are provided to push the main body 44 downwardly with respect to the bottle 68. This causes the bottle to exert pressure on the rod 52, and thereby slide the latter upwardly. The rod therefore presses downwardly on the top of the cap 72 with a force determined by the resiliency of the spring 60.

At the same time, the frusto-conical surface 62 causes an increasing compression force to be applied to the spring washer 64, thereby causing the latter to be squeezed in a radial direction against the cap 72. As can be seen from Figure 5, the pitch of the washer 64 corresponds with that of the thread of the neck 70, and the washer is so positioned with respect to this thread that the cap is deformed at the groove between adjacent outwardlyprojecting parts of the thread.

Thus, the cap 72 is deformed so that an internal thread is provided thereon, and very little pressure is exerted on the outwardlyprojecting portions of the thread on the neck 70 of the container 58, so that there is little risk of breaking the latter.

In the modification shown in Figure 6, the main body 44 is fixedly positioned, and the frusto-conical surface 62 is provided on a separate member 74 which has a pair of extensions 76 extending into the main body and carrying an annular piston 78 which is slidable within a bore 80 which surrounds the central bore 46. Passages 82 connect the central bore 46 with the bore 80.

In this case, the surface 62 is tapered inwardly towards its lower end. When pressurised fluid is delivered to the bore 46, the member 74 is lifted upwardly by the pressure acting on the lower surfaces of the piston 78, sa that the surface 62 causes the spring washer to be compressed radially. The washer 64 is connected by means of a member 84 to the main body 44, so as to maintain the washer in the correct vertical position.

The pressure in the bore 46 also acts to bias the rod 52 downwardly so that the spring 60 of the embodiment of Figure 5 is no longer required.

It will be appreciated that the thread forming means need not provide the closure with a continuous helical thread. Instead, the thread forming means may be provided with inwardly extending projections so that the helical engaging surface is discontinuous and the thread which is formed comprises a discontinuous helical line of inwardly extending deformations in the cap.

WHAT WE CLAIM IS:- 1. A method of closing a container comprising positioning a generally cylindrical closure on an externally screw threaded outlet of the container, positioning the closure within a thread forming means having a helical engaging surface and compressing the forming means radially so that the engaging surface exerts pressure on the closure between the outwardly projecting portions of the thread on the container outlet, thereby to deform the closure to produce a co-operating thread thereon.

2. Apparatus for closing a container comprising a support carrying a thread forming means which has a helical engaging surface and which is arranged to receive therein an externally screw threaded container outlet on which a generally cylindrical closure has been fitted, means being provided to compress the thread forming means radially around the closure thereby to form thereon a thread co-operating with a thread on the outlet.

3. Apparatus as claimed in claim 2, wherein the compressing means comprises a tapered surface engageable with the forming means or an element in contact therewith, and means to cause relative movement between the tapered surface and the forming

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. determined range to ensure that the spring washer engages the cap at the correct position. Figure 5 shows an alternative embodiment in which a main body 44 of the apparatus 42 is generally cylindrical and has a central bore 46 extending vertically therethrough. The bore 46 is divided into an upper and lower portion by an annular rim 48 the inner edge of which defines a hole 50. A vertical rod 52 extends through the hole, and a nut 54 is screwed onto the upper end of the rod, which is threaded for this purpose, to act as a stop. The lower end of the rod 52 has an outwardly extending rim 56 from which a cylindrical flange 58 depends downwardly. A coil spring 60 surrounds the rod 52 and extends between the upper surface of the rim 56 and the lower surface of the rim 48. The rod 52 is thereby biased downwardly by the spring 60 but slidable upwardly through the hole 50 against the bias of the spring 60. The lower end of the bore 46 is tapered outwardly as indicated at 62 to provide a frusto-conical surface. A thread forming means in the form of a spring washer 64, which may be similar to the washer 34 of Figure 3, is positioned with its axis vertical and within the lower end of the bore 46, and retained therein by a removable annular member 66 fixed to the bottom of the main body 44. In use of the apparatus a bottle such as that indicated at 68 having an externally threaded neck 70, is provided with a cylindrical cap 72 which is fitted over the neck 70. The neck and cap are then located in the lower end of the bore 46, with the upper end of the cap engaging the lower end of the rod 52 within the cylindrical flange 58. The spring washer 64 is situated around the cap 72. Means (not shown) are provided to push the main body 44 downwardly with respect to the bottle 68. This causes the bottle to exert pressure on the rod 52, and thereby slide the latter upwardly. The rod therefore presses downwardly on the top of the cap 72 with a force determined by the resiliency of the spring 60. At the same time, the frusto-conical surface 62 causes an increasing compression force to be applied to the spring washer 64, thereby causing the latter to be squeezed in a radial direction against the cap 72. As can be seen from Figure 5, the pitch of the washer 64 corresponds with that of the thread of the neck 70, and the washer is so positioned with respect to this thread that the cap is deformed at the groove between adjacent outwardlyprojecting parts of the thread. Thus, the cap 72 is deformed so that an internal thread is provided thereon, and very little pressure is exerted on the outwardlyprojecting portions of the thread on the neck 70 of the container 58, so that there is little risk of breaking the latter. In the modification shown in Figure 6, the main body 44 is fixedly positioned, and the frusto-conical surface 62 is provided on a separate member 74 which has a pair of extensions 76 extending into the main body and carrying an annular piston 78 which is slidable within a bore 80 which surrounds the central bore 46. Passages 82 connect the central bore 46 with the bore 80. In this case, the surface 62 is tapered inwardly towards its lower end. When pressurised fluid is delivered to the bore 46, the member 74 is lifted upwardly by the pressure acting on the lower surfaces of the piston 78, sa that the surface 62 causes the spring washer to be compressed radially. The washer 64 is connected by means of a member 84 to the main body 44, so as to maintain the washer in the correct vertical position. The pressure in the bore 46 also acts to bias the rod 52 downwardly so that the spring 60 of the embodiment of Figure 5 is no longer required. It will be appreciated that the thread forming means need not provide the closure with a continuous helical thread. Instead, the thread forming means may be provided with inwardly extending projections so that the helical engaging surface is discontinuous and the thread which is formed comprises a discontinuous helical line of inwardly extending deformations in the cap. WHAT WE CLAIM IS:-

1. A method of closing a container comprising positioning a generally cylindrical closure on an externally screw threaded outlet of the container, positioning the closure within a thread forming means having a helical engaging surface and compressing the forming means radially so that the engaging surface exerts pressure on the closure between the outwardly projecting portions of the thread on the container outlet, thereby to deform the closure to produce a co-operating thread thereon.

means or element thereby to compress the forming means.

4. Apparatus as claimed in claim 2 or 3, wherein the thread forming means comprises a spring washer.

5. Apparatus as claimed in any one of claims 2 to 4 further including a closure retaining member and means operable in use to bias the retaining member into engagement with the closure thereby firmly to hold the closure on the container outlet while the thread is formed on the closure.

6. A method of closing a container substantially as herein described.

7. Apparatus for closing a container substantially as herein described with reference to Figures 1 to 4, or Figure 5, or Figure 6 of the accompanying drawings.

8. A container when fitted with a closure by a method as claimed in claim 1 or claim 6.

9. A container when fitted with a closure by means of apparatus as claimed in any one of claims 2 to 5 and 7.