EP0061338A2

EP0061338A2 - Improvements in sealing machines for applying closures to containers

Info

Publication number: EP0061338A2
Application number: EP82301472A
Authority: EP
Inventors: James Frederick Herbert
Original assignee: Metal Closures Ltd
Current assignee: Arconic Closure Systems International UK Ltd
Priority date: 1981-03-24
Filing date: 1982-03-22
Publication date: 1982-09-29
Also published as: DE61338T1; EP0061338A3; ES264071Y; JPS57175593A; ZA821861B; AU8171382A; ES264071U; AU544804B2

Abstract

In a sealing machine for application of a metallic tamper-proof closure blank to a screw-threaded container having an abutment shoulder for engagement by the security band of the closure and a separate support shoulder beneath it comprising at least one head set for applying a blank to a container, each head is provided with an associated support member for the container support shoulder. The support member has an upstanding lip which fits under the support shoulder and has an extemal diameter less than the diameter of the path of the innermost edge of the tuck-under roller(s) of the head set in the retracted position. The upper surface of the support member outwardly of the lip is at a level lower than the level reached by the tuck-under roller(s) of the head set in the event of over-run in the absence of a container.

Description

The present invention relates to the application of closures to externally screw-threaded containers, such as screw-necked bottles, and in particular it relates to apparatus for applying closures to containers having crushable bodies, such as containers formed of plastics materials and to which a closure may be applied by placing an unthreaded metal closure blank over the mouth of the container and engaging such closure with the screw thread of the container in a thread-rolling operation.
Apparatus has been devised and widely used for applying unthreaded metal, usually aluminium, closure blanks to screw-threaded containers, in which the skirts of the closure blanks are brought into conformity with external thread on the container neck by a thread-rolling operation. In such apparatus the closure blank is subjected to heavy downward pressure during the thread-rolling operation. Such pressure is required for the formation of a seal between the container and the gasket or sealing material within the closure blank to be maintained after completion of the thread-rolling operation.
A normal glass bottle or jar has sufficient rigidity to withstand the applied vertical or "head" pressure, but a plastic bottle, such as may be produced from polyvinylchloride by blow moulding, may collapse to a considerable extent as a result of the axial head pressure, although the externally screw-threaded neck has sufficient strength to resist the radial pressure of the thread rollers. Because of the method of production of blow-moulded bottles, the wall thickness of the large diameter body portion of the bottle is far less than the wall thickness in the neck, which is particularly reinforced by the thread formations.
In our British Patent No. 1,244,653 we disclosed a sealing machine wherein the head pressure necessary for applying conventional aluminium closure blanks by thread rolling is transmitted through the relatively short, thick neck of the bottle to a support member arranged in supporting engagement with an abutment on the bottle neck below the bottle thread during the application of the closure to the bottle.
When a tamper-proof type metal closure is applied to a bottle, the free edge of the security band at the bottom end of the closure skirt is tucked under an abutment shoulder on the neck immediately below the thread. When the body of the bottle is not adequately resistant to axial pressure.a separate support shoulder may be provided on the bottle neck for engagement by a support member on the sealing machine because the bottle cannot be supported on the abutment shoulder under which the security band is to be tucked by roller action.
A conventional sealing machine for applying a tamperproof closure to a container includes a head set which is rotatable about a vertical axis and which is vertically movable in relation to a support for the container, the head set including a pressure block, which applies vertical pressure to the closure and is free to rotate about the axis of the head set,and one or more thread forming rollers and one or more tuck-under rollers, said rollers being movable radially in relation to the axis of the head set from an outward retracted position to an inward operating position when the pressure block meets resistance to its downward movement. A head set of this type is later referred'to herein as a head set of the type described.
In existing plastic bottles adapted to receive tamperproof closures the support shoulder is arranged close to the abutment shoulder for the security band to minimise the amount of material required for the production of the bottle.
A problem which has arisen when employing a support member shaped as shown in British Patent No. 1,244,653 is that under certain circumstances the tuck-under roller(s) may foul the support member. In particular these circumstances arise when the head set including the tuck-under roller(s), is set in operation above a support member which, perhaps due to an interruption of flow of bottles to the sealing machine, does not have a bottle supported therein. The head set will then "over-stroke", causing the tuck-under roller to be moved down so far as to foul the support member.
However in such circumstances since the head set does not meet any resistance to its downwardly moving pressure block, inward movement of the tuck-under roller(s) and the thread roller(s) towards the closure blank is not triggered and each tuck-under roller remains in its retracted position.
According to the invention there is provided a sealing machine for the application of an unthreaded metallic tamper-proof closure blank to an externally screw-threaded container having an abutment shoulder for engagement by the security band of said closure and a separate support shoulder beneath said abutment shoulder and adapted to rest on a support member of said sealing machine during application of a blank to said container, said machine comprising at least one head set of the type described having an associated support member to receive said support shoulder characterised in that the support member has an upstanding lip for supporting the support shoulder of a container, said lip having an external diameter less than the diameter of the path of the innermost edge of the tuck-under roller(s) in the retracted position and said support member having an upper surface radially outwardly from said lip at a level lower than the level reached by the tuck-under roller(s) in the event of over run in the absence of a container from the support member. The upper surface of the support member may be flat, but it is convenient if it slopes up slightly to the lip, from an outer portion by which the support member may be secured in the sealing machine. Usually the sealing machine will be a multi-head machine, with a support member arranged at each head set station.
To help understanding of the invention, a specific embodiment thereof will now be described with reference to the accompanying drawings, in which:-

Figure 1 is a diagrammatic elevation of one head set of a multi-head sealing machine; and
Figure 2 is a plan view of the neck support member shown in Figure 1.

In Figure 1 the bottle 1 is shown immediately prior to the commencement of the application of a tamper-proof closure. In the application of the blank to the bottle 1 thread is rolled into the skirt 2a of the blank and the security band 2b is tucked under the abutment shoulder by the roller 4. The head set, which carries thread rollers 3 and tuck-under rollers 4, has been lowered to cause its pressure block 5 to press the blank 2 down against the top of the bottle neck. The pressure block 5 is spring- or fluid-loaded and is vertically movable in relation to the rotating head set spindle 5a. When the pressure block encounters sufficient resistance to downward movement, it moves upward in relation to the spindle 5a and this triggers the inward movement of the rollers 3 and 4. At the position shown the rollers 3 and 4 are still in their retracted position and their movement towards their operating position, in which they act on the closure blank 2 has not yet commenced.
The bottle 1 is supported in the machine by a support member 6. The support member 6 and the head set rotate about a common axis in the conventional manner for a multi-head application machine.
In accordance with the present invention the support member 6 is provided with an upstanding lip 8 which defines an essentially semi-circular recess to receive the neck of the bottle 1. A support shoulder 9 on the neck of the bottle rests on the semi-circular lip 8 in support of the bottle. The underside of the support member is preferably curved to conformity with the shape of the bottle to hold the bottle against tilting.
In the absence of a bottle the head set over-strokes, bringing the tuck-under roller 4 approximately to a level 14 below the level 12 at which a bottle, via its support shoulder is normally supported on the upstanding support lip 8. However the tuck-under roller does not foul the support member 6 since its inclined upper surface 7 is at a sufficiently low level compared to level 14.
When the pressure block 5 encounters normal resistance to its downward movement the roller 4 hinges inwardly to act on the lower margin of the security band 2b.
As may be seen in Figure 2, the lip 8 defines, in plan, a semi-circular recess 15 for accommodating the neck of the bottle. To provide for free entry and exit of bottles into the recess 15, it cannot have a circumferential extent of more than a semi-circle where the radius of curvature of the recess is such as to closely fit the necks of the bottles. However the lip 8 does have wings 16 which continue beyond the margins 17 of a semi-circle. The wings 16 are slightly diverging from each other. The wings 16 assist in stably supporting a bottle if the pressure head acts slightly eccentrically or if irregularities in the bottle should cause the neck to tilt under pressure from the pressure block.
The wings may be essentially parallel, instead of being slightly divergent as shown. In some instances the wings, whether parallel or divergent, may be curved in the same sense as each other. This is convenient where the bottle is transferred to a support member 6 carried by one star wheel from a recess in an adjacent star wheel.

Claims

1. A sealing machine for the application of an unthreaded metallic tamper-proof closure blank to an externally screw-threaded container having an abutment shoulder for engagement by the security band of said closure and a separate support shoulder beneath said abutment shoulder and adapted to rest on a support member of said sealing machine during application of a blank to said container, said machine comprising at least one head set of the type described having an associated support member to receive said support shoulder characterised in that the support member has an upstanding lip for supporting the support shoulder of a container, said lip having an external diameter less than the diameter of the path of the innermost edge of the tuck-under roller(s) in the retracted position and said support member having an upper surface radially outwardly from said lip at a level lower than the level reached by the tuck-under roller(s) in the event of over run in the absence of a container from the support member.

2. A sealing machine according to claim 1 further characterised in that the upper surface of said support member slopes downwardly from said lip.

3. A sealing machine according to claim 1 or 2 in which said lip is substantially semi-circular and terminates in parallel or slightly diverging wings at its ends.