Patent Application
20240286786
This application claims priority to French Application No. 2301859, filed Feb. 28, 2023, the contents of which are incorporated herein by reference in their entirety.
The present invention relates to an assembly for closing a tube, said assembly comprising:
The flexible tubes are known to be equipped with a cap so that they can be closed between two uses. This allows to prevent the contents of the tube from spilling out. This also allows to prevent pollutants from entering the tube. However, a cap of this type alone does not usually guarantee a perfect airtight seal.
To ensure that the tube is airtight before it is used for the first time, it has been known to be sealed with a foil seal that is glued to the open end of the neck. The foil seal allows the product contained in the tube to be kept hermetically sealed during its storage prior to its first use, which represents a very important part of the overall service life of the tube.
To allow a user to peel off the foil seal easily, it has a tab that is not glued to the neck. The tab protrudes radially from the neck to provide a grip for the user.
When the cap is screwed onto the tube for the first time during production, the tab is folded down against the external face of the neck so that it is interposed between an internal thread of the cap and an external thread of the neck.
To make it easy to screw the cap onto the neck, there is a radial clearance between the cap and the neck. This radial clearance also allows to prevent the tab from being too tight between the cap and the neck.
However, it has been observed that, in some cases, one angular sector of the cap ends up tight on one side of the neck, while the diametrically opposite angular sector accumulates all the radial clearance.
This problem is particularly acute when the production rates of the tubes are very high. In this case, the cap is screwed onto the neck at high speed.
When the tab is pinched between the cap and the neck as it is screwed on, it is driven in rotation by the cap. This twisting movement damages the foil seal. In the worst case, the torsion of the foil seal causes it to tear or peel off, and the foil seal can no longer fulfil its sealing function. At best, unsightly creases form in the foil seal. This problem is particularly acute when the production rates of the tubes are very high. The cooling time of the weld between the foil seal and the neck is then insufficient to withstand the torsional stress.
In addition, this uneven distribution of the radial clearance between the cap and the neck means that the cap is generally tilted in relation to the main axis of the neck. The result is an unsightly tube. In addition, when the cap is tilted, this can cause a friction between a shoulder of the tube and an external skirt of the cap. Such rubbing leaves marks on the surfaces that are rubbed, causing aesthetic defects and a detachment of particles that can pollute the environment.
In addition, this uneven distribution of the radial clearance can lead to the cap jamming in the angular sector accumulating all the radial clearance when the screwing torque required to seal the tube is high.
Some containers already comprise a neck and a cap equipped with means for centering the cap in relation to the neck. However, these means for centering only allow the cap to be centered once it has been screwed in. In particular, this does not solve the problem posed by damage to the foil seal during screwing.
The present invention proposes an assembly for closing a tube, said assembly comprising:
characterised in that it comprises means for centering the cap relative to the neck while it is being screwed on, formed by at least one projection which extends from the thread root of one of the external thread or the internal thread and the height of which is less than that of said thread, a residual radial clearance remaining between the cap and the neck at the level of the projections in the screwed position of the cap on the neck.
According to another characteristic of the assembly produced in accordance with the teachings of the invention, the external thread or the internal thread comprises a plurality of projections which are evenly distributed around the main axis.
According to another characteristic of the assembly produced in accordance with the teachings of the invention, there are four projections.
According to another characteristic of the assembly produced in accordance with the teachings of the invention, each projection is arranged on the external thread of the neck.
Another characteristic of the assembly produced in accordance with the teachings of the invention is that the cap and the neck are made of a rigid plastic material, such as HDPE.
According to another characteristic of the assembly produced in accordance with the teachings of the invention, each projection has the same rigidity as the thread crest of the other of the external thread or the internal thread
According to another characteristic of the assembly produced in accordance with the teachings of the invention, each projection is in the form of a rib which axially connects two adjacent turns of the thread.
According to another characteristic of the assembly produced in accordance with the teachings of the invention, at least one of the projections is arranged between the two upper end turns of the thread.
According to another characteristic of the assembly produced in accordance with the teachings of the invention, it comprises a foil seal closing said neck, the foil seal having a radial gripping tab folded down against the external thread of the neck, the radial tab being received in a nominal radial clearance between the upper end turn of the internal thread and the neck.
According to another characteristic of the assembly produced according to the teachings of the invention, the width of the projection, taken in the orientation of the turn, is less than its height.
According to another characteristic of the assembly produced in accordance with the teachings of the invention, the upper end turn of the internal thread has a decreasing height from bottom to top so that the nominal radial clearance between the thread crest of said end turn and the thread root of the external thread of the cap is greater than the nominal radial clearance between the other turns of the internal thread and the external thread.
According to another characteristic of the assembly produced in accordance with the teachings of the invention, the neck comprises a non-threaded upper end portion, said portion having a frustoconical shape.
The invention also relates to a tube comprising a closure assembly made in accordance with the teachings of the invention.
The invention also relates to a tube head of said assembly.
Further characteristics, purposes and advantages of the invention will be apparent from the following description, which is purely illustrative and not limiting, and which should be read in conjunction with the appended drawings briefly described below.
For the remainder of the description, elements with an identical structure or similar functions will be designated by a same reference.
For the remainder of the description, we shall adopt an axial direction which corresponds in the figures to that of the main axis “A” of the neck of the closure assembly. Radial directions directed orthogonally to the axial direction will also be adopted, radiating from the main axis. Finally, a circumferential direction directed orthogonally to the axial and radial directions will also be adopted.
The closure assembly 16 comprises a tube head 18, more particularly visible in
In the embodiment shown in the figures, the head 18 has a shoulder 28 which allows to connect the neck 20 to the body 12. The neck 20 extends axially from the center of the shoulder 28. By way of illustration, the neck 20 and the shoulder 28 are designed in one-part and are continuous in terms of material.
The neck is preferably made of a rigid plastic material, such as high-density polyethylene (HDPE) or polypropylene (PP).
A user can discharge the content of the tube 10 through the central opening 26 by squeezing the body 12.
The closure assembly 16 also comprises a cap 30, which can be seen in
The neck 20 comprises a helical external thread 32 which projects radially outwards from an external side wall 34 of the neck 20. The external thread 32 is made in one-part with continuity of material with the neck 20.
The neck 20 comprises an unthreaded upper end portion 20A between an upper end turn 32s of the external thread 32, referred to as the last turn 32s, and the upper edge 43.
The cap 30 comprises a cylindrical skirt 36 which extends axially downwards from a top radial wall 38 of the cap 30. An internal helical thread 40 projects radially inwards from an internal wall of the skirt 36. The internal thread 40 complements the external thread 32 to allow the cap 30 to be screwed onto the neck 20.
In this case, the internal thread 40 is made in one-part with continuity of material with the skirt 36.
The skirt 36 is made in one-part from the same material as the top wall 38. More particularly, in the embodiment shown in the figures, the cap 36 is made in one-part with continuity of material.
The cap 30 is preferably made of a rigid plastic material, such as high-density polyethylene (HDPE) or polypropylene (PP).
Preferably, the two threads 32, 40 are made of the same material.
Each thread 32, 40 has between two and three turns, for example 2.5 turns.
The external thread 32 of the neck 20 has a thread root 32A defined as the bottom of the helical groove delimited between two adjacent turns of the external thread 32. The external thread 32 further has a thread crest 32B defined as the free radial end helical ridge of the external thread 32. Finally, a radial height “He” of the external thread 32 is defined as being the radial distance between the thread root 32A and the thread crest 32B.
Similarly, the internal thread 40 of the cap 30 has a thread root 40A defined as the bottom of the helical groove delimited between two adjacent turns of the internal thread 40. The internal thread 40 further has a thread crest 40B defined as the free radial end helical ridge of the internal thread 40. Finally, a radial height “Hi” of the internal thread 40 is defined as being the radial distance between the thread root 40A and the thread crest 40B.
The radial height “Hi” of the internal thread 40 is here equal to the radial height “He” of the external thread 32.
As a non-limiting example, the radial height “Hi” of the external thread 40 is equal to 0.8 mm.
The neck 20 is equipped with a foil seal 42 which closes its central opening 24. The foil seal 42 is in the form of a disc, the periphery of which is attached to an upper end edge 43 of the neck 20 forming a periphery of the central opening 24, for example by gluing. The foil seal 42 is for example formed by a sheet of laminate comprising a barrier layer to prevent the passage of air, such as a layer of aluminium. The thickness of the foil seal 42 is very thin, for example less than 100 μm, preferably around 80 μm.
When the cap 30 has been screwed onto the neck 20, a face 44 of the top wall 38 is tightened axially against the free end edge 43 of the neck 20 in order to grip the periphery of the foil seal 42. This allows the foil seal to be held firmly in position to close the central opening 24.
The foil seal 42 further comprises a radial gripping tab 42A which extends radially from an edge of the disc-shaped portion. The radial tab 42A has the same thickness as the disc-shaped portion of the foil seal 42. Before the tube 10 is used, the radial tab 42A is folded down against the external face 34 of the neck 20.
In the embodiment shown in the figures, at least one area of the radial tab 42A covers an angular sector of at least the upper end turn 32s of the external thread 32, as shown in
In a variant of the invention not shown, the axial distance between the upper end edge of the neck and the upper end turn of the external thread is greater than the length of the radial tab. In this way, the radial tab of the foil seal does not come into contact with the external thread when it is folded down.
To allow the cap 30 to be screwed on and off the neck 20 without friction, a nominal radial clearance “j0” is provided between the external thread 32 of the neck 20 and the internal thread 40 of the cap 30. This nominal radial clearance “j0” must be high enough to take into account the manufacturing tolerances of the neck 20 and of the cap 30.
This nominal radial clearance “j0” has a value determined at the level of a free upper end of the neck 20. This nominal radial clearance “j0” is 0.27 mm, for example. This nominal radial clearance “j0” also prevents the radial tab 42A of the foil seal 42 from being pinched between the external thread 32 and the external thread 40 when the cap 30 is screwed onto the neck 20.
A portion of the tab is therefore designed to be received in the nominal radial clearance “j0” between an upper end turn 40s of the external thread 40 and the neck 20.
Ideally, this nominal radial clearance “j0” should be distributed more or less equally around the neck 20. However, it has been found that in some cases, the cap 30 can become so eccentric with respect to the neck 20 that one side of the cap 30 is completely tightened against the neck 20, while the nominal radial clearances “j0+j0” of the two opposite sides, i.e. 0.54 mm in this case, are accumulated on the diametrically opposite side, as shown in
When the tab 42A of the foil seal is completely tightened between the external thread 32 and the internal thread 40 during the screwing operation, it is driven in rotation with the cap 30 by friction. This induces a torsional torque in the foil seal 42, causing it to become damaged and/or detached from the edge 43.
Furthermore, even when the neck 20 is not equipped with a foil seal 42 or the radial tab 42A is not on the tightened side of the cap 30, this configuration causes the cap 30 to tilt, tilting it relative to the main axis “A” of the neck 20.
To solve these problems, the invention proposes equipping the closure assembly 16 with means for centering the cap 30 relative to the neck 20 while it is being screwed on.
The means for centering are formed by at least one projection 46 which extends radially from the thread root of one of the external thread 32 or the internal thread 40 to a free end.
In the embodiment shown in
In a variant of the invention not shown, only the internal thread 40 comprises such projections 46.
According to another variant of the invention, not shown, both the external thread 32 and the internal thread 40 comprise such projections 46.
The external thread 32 comprises a number of projections 46 which are evenly spaced around the main axis “A”. For example, there are at least three and preferably at least four projections 46.
The height “h” of the projection 46 is less than that of said external thread 32. In particular, this ensures that the projection 46 does not prevent the cap 30 from rotating relative to the neck 20. In particular, this allows the internal thread 40, which does not comprise the projections 46, to be engaged in the external thread 32 comprising the projections 46, so that the thread crest 40B can slide against the projections 46. In this way, the projections 46 act as spacers interposed radially between the two threads 32, 40 to ensure a minimum radial clearance between the cap 30 and the neck 20.
In particular, to prevent the projections 46 from interfering with the screwing stroke of the cap 30, the height “h” of the projections 46 is less than half the nominal radial clearance “j0” between the external thread 32 and the internal thread 40 in the screwed position of the cap 30 on the neck 20. Preferably, there remains a residual radial clearance “j1” between the cap 30 and the projections 46, as shown in
When the neck 20 is equipped with a foil seal 42, the height “h” of a projection 46 is greater than the thickness of the radial tab 42A.
The presence of projections 46 allows to ensure that there is always a minimum radial clearance “j2” equal to the height “h” of a projection 46 between the cap 30 and the neck 20. This minimum radial clearance “j2” is greater than the thickness of the radial tab 42A of the foil seal 42.
Furthermore, in order to reduce the friction surface between the projections 46 and the thread 40 not comprising the projections 46, each projection 46 advantageously has a very small width in the circumferential direction, for example the width of each projection 46 in the circumferential direction is less than its height “h” in the radial direction.
Each projection 46 is in the form of a rib which axially connects two adjacent turns of the thread 32 which it equips. The rib thus extends in a radial axial plane.
In addition, each projection 46 has the same rigidity as the thread crest 40B against which it is intended to foil seal. In particular, the projection 46 is sufficiently rigid not to be significantly deformed when the cap 30 is screwed onto the neck 20.
So that the projections 46 can distribute the nominal radial clearance “j0” around the neck 20 as soon as the cap 30 begins to be screwed on, at least one of the projections 46, preferably at least two, is arranged between the two upper end turns of the external thread 32. All the projections 46 are arranged so as to face the thread crest 40B of the internal thread 40.
According to a first embodiment of the invention shown in
In addition, the height “He” of the external thread 32 remains constant. Thus, the thread crest 32A of the external thread 32 extends over a cylinder of revolution centered on the main axis “A”.
As a result, the nominal radial clearance “j0” with the cap 30 is the same along the entire axial length of the neck 20. This nominal radial clearance “j0” is 0.27 mm.
The radial tab 42A of the foil seal 42 has a thickness of 80 μm. The height “h” of each projection 46 is approximately 0.17 mm, i.e. approximately twice the thickness of the radial tab 42A. This allows sufficient minimum radial clearance “j2” to be maintained between the cap 30 and the neck 20 so that the radial tab 42A can be received without radial tightening between the cap 30 and the neck 20.
In addition, there remains a residual radial clearance “j1” of 0.1 mm between the internal thread 40 and the projections 46 when the cap 30 is in its screwed position on the neck 20.
According to a second embodiment of the invention shown in
For example, the nominal radial clearance “j0” between the thread crest 32B of the last turn 32s of the internal thread 32 and the thread root 40A of the last turn of the external thread 40 of the cap 30 is 0.46 mm, while the nominal radial clearance “j0” between the other turns of the internal thread 32 and the external thread 40 is 0.27 mm.
To accentuate this nominal radial clearance “j0” as the free upper end of the neck is approached, the unthreaded upper end portion 20A of the neck 20 has a frustoconical shape whose diameter reduces from root to top.
Thus, the nominal radial clearance “j0” between the external face 34 of the unthreaded portion and the crest 40B of the thread of the last turn of the internal thread 40 is, for example, equal to 0.37 mm instead of 0.27 mm as would be the case if the external face 34 of the neck 20 were entirely cylindrical.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2301859 | Feb 2023 | FR | national |
