DEVICE FOR THE FABRICATION OF TUBES WITH A NON-CIRCULAR SECTION ORIFICE GEOMETRY AND FABRICATION METHOD

The invention concerns in particular a device for moulding an article in which the article is obtained by compression moulding a dose (14) of material in the molten state and comprises at least one orifice (23) after the compression moulding operation, said device comprising at least one die (10), one mandrel (11) cooperating with said die (10) to effect the operation of compression moulding of the dose and one orifice rod (12) sliding in said die (10), said device further comprising a shape endpiece (13) placed between the mandrel (11) and the orifice rod (12) to form the orifice (23) of the article.

CORRESPONDING APPLICATION

The present application claims priority to earlier European application No EP20194767.8 filed on Sep. 7, 2020 in the name of AISAPACK HOLDING SA, the entire content of this earlier application being incorporated by reference in the present application.

TECHNICAL FIELD

The present invention concerns tubes the heads of which are produced by compression moulding, the moulding operation being also used to weld the tubular skirt to the tube head. The present invention enables the production of orifice geometries the section of which is not circular and applies in the packaging field and in particular in that of flexible tubes intended to contain creams or pastes such as toothpaste. The invention also concerns a method for producing that head and a tube with such a head.

PRIOR ART

Tube heads produced by compression-moulding of a dose of resin in the molten state have been known for many years and described for example in the publication WO 2007/125481 the content of which is incorporated by reference in the present application. These tube heads are welded to the skirt of the tube conjointly with the compression moulding operation forming the head from a dose of material. In this method, the welding operation does not necessitate the application of heat other than that of the molten resin used to mould the tube head. The tube obtained by this method has advantageous aesthetic properties in the welding zone. In particular the transition between the skirt and the tube head forms a smooth and continuous surface. In this packaging the transition zone between the skirt of the tube and the tube head is not perceptible by the user, which represents a great benefit for the tubes used in the field of cosmetic products. However, with the known prior art devices it is not possible to produce non-circular section orifices in the tube head.

The invention in particular enables this drawback to be remedied.

Publication FR 2 846 594 discloses a method and a device for manufacturing plastic molded parts, in particular elements forming nozzles on packaging containers, preferably heads for packaging tubes.

SUMMARY AND PRINCIPLE OF THE INVENTION

The invention relates in particular to means and methods for fabricating a tube the head of which is produced by compression moulding and the orifice of which serving to extract the product is of non-circular section and/or oriented and/or of complex section and/or comprises a plurality of orifices of different shapes. The means and methods in accordance with the invention also make it possible to optimize the distribution of the material and to prevent defects in the heads produced.

The invention also relates to a tube the geometry of the orifice of which is for example oriented relative to printing on the skirt or relative to the cap.

The invention also relates to a tube having a complex section orifice geometry or a plurality of orifices of different shapes.

The tube in accordance with the invention is characterized in particular by an upper face of the neck with a central surface and a peripheral surface, the orifice opening in the central surface and the two surfaces being offset relative to one another.

The invention also relates to a tube including a plurality of orifices.

The invention also relates to a method of carrying out the invention.

REFERENCE NUMBERS AND BRIEF DESCRIPTION OF THE DRAWINGS

Prior Art (FIGS.1and2)

FIG.1illustrates a tube produced in accordance with the prior art. This tube1comprises a tube head2, a skirt3overmoulded by compression moulding and a circular section orifice4. The head further comprises fixing means for a cap, for example a screw thread8, and a peripheral surface9. The reference5indicates the transition zone between the head2and the skirt3that forms a smooth and continuous surface thanks to the compression moulding fabrication method.

FIG.2illustrates the prior art tube1in a view from above. In this representation the circular geometry of the orifice4corresponding to the prior art can be seen.

The means and the method for obtaining the tube fromFIGS.1and2are described in the publication WO2007/125481 incorporated by reference in the present application, in particular inFIGS.1to8and the description of those figures.

EMBODIMENTS OF THE INVENTION

FIGS.3to6and18illustrate in section embodiments of devices in accordance with the present invention for producing tube heads and tubes.

FIGS.7to11illustrate embodiments of heads and tubes and orifice geometries in accordance with the invention in section and in views from above.

FIG.12illustrates a feature of the tubes at the level of the transition zone between the tube head and the skirt.

FIGS.13to17illustrate embodiments of means used in devices in accordance with the present invention.

In embodiments the invention concerns a device for moulding an article in which the article is obtained by compression moulding a dose of material in the molten state and comprises at least one orifice after the compression moulding operation, the device comprising at least one die, one mandrel cooperating with said die to effect the compression moulding operation of the dose and one orifice rod sliding in said die, the device further comprising a shape endpiece placed between the mandrel and the orifice rod to form the orifice of the article.

In embodiments of the invention the shape endpiece may be on the rod or on the mandrel or partly on the rod and partly on the mandrel.

In embodiments of the invention the device comprises at least one means for maintaining the mandrel and the orifice rod in contact via the shape endpiece.

In embodiments of the invention, the means may be a mechanical or pneumatic spring.

In embodiments of the invention, the device comprises a rod exit abutment for adjusting the amplitude of the axial movement of the rod.

In embodiments of the invention, the device comprises a second pressurization element for exerting a high pressure at the end of moulding, said second element being a short travel ram.

In embodiments of the invention, said device comprises a transition abutment for switching from the low pressure exerted by the first pressurization element to the high pressure exerted by the second pressurization element.

In embodiments of the invention, said device comprises a bush for centring the dose.

In embodiments the invention concerns a method for forming an article with an orifice from a dose of material in the molten state, said method using a die cooperating with a mandrel, an orifice rod and a shape endpiece placed between the mandrel and the orifice rod, the article being formed by compression moulding the dose between the die and the mandrel and the orifice of the article being created by the shape endpiece surrounded by material during the compression moulding operation.

In embodiments of the invention, a first pressurization means is used to bring into contact the shape endpiece, the mandrel and the orifice rod during the closing of the mould and a second pressurization means is used to exert a high pressure at the end of moulding.

In embodiments of the invention, a transition abutment is used to switch from the pressure exerted by the first pressurization means to the pressure exerted by the second pressurization means.

In embodiments the invention concerns an article comprising at least one central surface, one peripheral surface and one orifice formed by a shape endpiece, the orifice opening in the central surface and said central and peripheral surfaces being offset relative to one another.

In embodiments of the invention, the offset between the surfaces forms a recess or a protrusion.

In embodiments of the invention, said orifice comprises at least two distinct orifices having the same geometry or a different geometry.

In embodiments of the invention, the article may be a tube head or a tube.

DETAILED DESCRIPTION

FIG.1illustrates a tube produced in accordance with the prior art. This tube1comprises at least one tube head2, one skirt3overmoulded by compression moulding and one orifice4of circular section. The tube head2is fabricated by compression moulding a dose of plastic material in the molten state. The skirt3is assembled to the tube head2during the moulding of the head by a so-called overmoulding operation consisting in positioning the skirt in the mould and using the heat of the moulded plastic material to effect the assembly between the tube head2and the skirt3. The prior art tubes produced in accordance with this method have the advantage of having a perfect transition zone5between the skirt3and the tube head2. For this reason the tubes are often used in the cosmetic field where the aesthetic criteria of the packaging are of prime importance.

FIG.2illustrates the prior art tube1in a view from above. There is seen in particular the geometry of the orifice4that forms a circular section opening. This orifice4is used to extract the product from the packaging.

It is nevertheless required in some cases to fabricate tubes having a head the orifice of which has a different section, that is to say in particular a non-circular section, and for example having any shape or indeed including a plurality of orifices of any shape, either for reasons of practicality or for reasons of marketing or for other reasons, for example stemming from the product contained in the tube and/or its use. The device known from WO2007/125481 not allowing any such freedom, it is modified in accordance with the invention as described hereinafter.

An object of the present invention is therefore to improve the known products and methods.

To be more precise, one object of the present invention is to propose means enabling production by compression moulding of a container in the form of a tube having an orifice of any shape.

Another object of the present invention is to propose a simple and reliable solution that can easily be fitted to machines currently in service. It is therefore necessary to avoid a solution and means that are radically different but rather to propose means that are easily applicable to existing machines.

Thus,FIG.3illustrates one embodiment of a device in accordance with the invention for producing a tube head or a tube in accordance with the invention in which the section of the orifice is not circular. This device comprises a mould comprising at least one die10, one mandrel11, one orifice rod12and a shape endpiece13. The orifice rod12slides in the die10and includes said shape endpiece13at its end.

During the formation of the tube (in the operation of compression moulding the head2on the skirt3, see for example FIGS. 6 and 7 of WO2007/125481) in accordance with the present invention the shape endpiece13is maintained in contact with the mandrel11and is driven by the relative movement between the die10and the mandrel11during the compression moulding operation.

To be more precise, the orifice rod12no longer has a continuous shape (in section) as in WO2007/125481 but comprises at its end in contact with the mandrel11a shape endpiece13that is used to create the geometry of the orifice23of the tube. With this construction it is possible to create any shape of orifice23of the tube (or of the tube head), without significant modification of the rod12. The endpiece13may be formed directly in the material of the rod or be an attached part (for example screwed on, welded on or stuck on, etc.). The material may be the same or a different material.

A force is exerted on the rod12to maintain the contact between the shape endpiece13and the mandrel11during the moulding operation and to prevent the molten material entering between the mandrel11and the endpiece13.

FIG.4illustrates another embodiment in which the shape endpiece13is fixed to the mandrel11(such as for example an attached part fixed by gluing, welding or screwing, etc.) or forms part of the mandrel11. The principle is the same as that described with reference toFIG.3.

In variants, the shape endpiece13may be in several parts, for example in two (or more) parts, at least one of which is on the mandrel11and the other on the rod12.

FIG.5illustrates an embodiment of a device in which the dose of plastic material is deposited on the mandrel11. The operating principle is the same as inFIG.3or4, the device simply being turned through 180°, the mandrel11being at the bottom and the die10at the top. The shape endpiece13may be placed on the mandrel11or on the rod12or in part on one of them and in part on the other of them.

FIG.6illustrates the device fromFIG.3but in another configuration: in thisFIG.6the length of the shape endpiece13along the axis of the rod12is greater than the intended thickness of the tube head at the level of the peripheral surface26so that the shape of the tube head will be different, as explained below.

FIGS.7and8illustrate a tube20in accordance with one embodiment of the invention obtained for example using the device illustrated inFIGS.3to5. This tube20has an orifice23with a rectangular section geometry (seeFIG.8), which is advantageous for delivering a product with a small thickness for example. The tube20in accordance with the invention has on the one hand the advantage of the quality of the transition zone between the skirt22and the tube head21that forms a continuous surface with no asperity stemming from the compression moulding method used and described hereinabove and on the other hand the advantage of having a complex non-circular section orifice geometry better suited to the extraction of the product in the intended application. Generally speaking, the shape endpiece13therefore has a shape corresponding to that of the orifice23in such a manner as to form that geometry during the compression moulding process.

In accordance with this embodiment of a tube in accordance with the invention illustrated inFIGS.7and8the front face of the neck of the tube head21comprises a central surface25and a peripheral surface26that are offset relative to one another. As can be seen inFIGS.7and8the orifice23opens in the central part of the neck at the level of the central surface25in a recess27formed by the relative offset of the surfaces25and26.

FIGS.9and10illustrate another embodiment of a tube in accordance with the invention obtained for example using the device illustrated inFIG.6. In this embodiment the tube1has a shar-shaped geometry of the orifice23that can be used for marketing reasons for example.

In accordance with this embodiment illustrated inFIGS.9and10the front face of the neck of the tube head21comprises a central surface25and a peripheral surface26that are offset relative to one another but in the opposite direction to that inFIGS.3and4. The orifice4opens in the central part of the neck at the level of the central surface25on a protrusion28formed by the offset of the surfaces25and26. The formation of a recess27or of a protrusion28is produced by the length of the endpiece13relative to the intended thickness of the shoulder at the level of the peripheral surface26: as inFIG.7to produce a recess27or as inFIG.9to produce a protrusion28.

In fact, as the rod12and the mandrel11are always in the same position pressed one against the other, it is possible to form a recess27or a protrusion28exclusively by adjusting the length of the endpiece13relative to the thickness of the shoulder.

In accordance with embodiments of the invention, when the offset between the surfaces25and26forms a recess27(for example as illustrated inFIG.7) the value of the offset between the surfaces25and26is less than 5 mm and preferably less than 0.5 mm.

In accordance with embodiments of the invention, when the offset between the surfaces7and9forms a protrusion28(for example as illustrated inFIG.9) the value of the offset between the surfaces25and26is less than 10 mm and preferably less than 0.5 mm.

In accordance with embodiments of the invention the offset between the surfaces25and26is close to zero. In these embodiments the value of the offset is less than 0.4 mm in both directions (“recess” and “protrusion”) and preferably less than 0.2 mm.

The tubes obtained in accordance with the invention are characterized in particular by the fact that the thickness of the wall of the tube measured at the level of the central surface7over a large number of tubes from the same production run varies very little whereas the thickness measured at the level of the peripheral surface on the same samples varies more.

In accordance with the invention it proves that the thickness measured at the level of the central surface7does not depend on variations in the weight of the dose of resin used to mould the tube head whereas the variation of the thickness of the wall at the level of the surface9does depend on variations in the weight of the dose.

Consequently, either the mould is designed so that the tube head includes a protrusion28with small variations that depend on the variation in the weight of the dose as illustrated inFIG.9and with a device as illustrated inFIG.6or the mould is designed so that the tube head includes a recess27with small variations that depend on the variations in the weight of the dose as illustrated inFIG.7and with the device in the configuration fromFIG.3.

Thus the present invention enables variations in the quantity of material in the dose to be circumvented and to be compensated directly during the compression moulding method in accordance with the invention to produce a product without defects.

FIG.11illustrates another embodiment of the invention. In this embodiment the tube20includes a multiplicity of orifices23a,23b,23cand23d. In this embodiment the orifices23aand23chave a circular section geometry and the orifices23band23dhave a square section geometry. Other configurations may of course be envisaged both with regard to the number of orifices and with regard to their shape or their size. These orifices are formed by the shape endpiece13that may be on the rod13, on the mandrel11or on both. For example, it may be envisaged that the endpiece forming the orifices of one geometry is on one of the rod or the mandrel and that the endpiece forming the orifices with a different geometry are on the other of the rod and the mandrel. Of course, other configurations are possible as a function of circumstances, required shapes, etc.

Any shape may be given to the orifice using the principles of the present invention as described in the present application and the invention is not limited to those illustrated by way of non-limiting example.

FIG.12illustrates a feature of the tubes21produced in accordance with the invention that is also a feature of the prior art tubes in which the head is moulded by compression moulding. These tubes21have a transition zone5of high quality between the skirt3and the head2. These tubes21are characterized by the fact that the external surface6is perfectly continuous and without asperities in the zone5, which is a preferred feature in the context of the present invention for the reasons explained hereinabove.

The tubes may be of circular or oval or elliptical section, for example, or oblong, or square, and the principles of the present invention apply to all tube shapes.

The devices described and illustrated have been simplified to clarify the description. These devices are not represented but are known in principle in the prior art and comprise in particular mould extraction means, opening and closing means, means for cooling the compression moulding means, means for loading and retaining the skirt of the tube, and means for receiving and guiding the dose of plastic material.

FIGS.13to17illustrate embodiments of the means used to implement the device and the method in accordance with the invention. In these examples and for simplicity only the functional parts linked to the invention are represented.

FIG.13illustrates a first embodiment of the means used to carry out the invention. In this embodiment the device includes in particular means that enable the mandrel11and the orifice rod12to be maintained in contact during the compression moulding operation via the shape endpiece13. In particular such means are preferably employed to prevent moulded material being inserted between the shape endpiece13and the mandrel11. A first embodiment illustrated inFIG.13comprises a passive element such as a mechanical or pneumatic spring30to exercise this function. An alternative that is not represented may use an active element such as a preferably pressure-controlled ram. This solution enables adjustment of the axial force on the orifice rod12as a function of the forces employed during moulding. AsFIG.13illustrates, the device also comprises guide means29that allow the axial movement of the orifice rod12and a rod exit abutment32that enables adjustment of the amplitude of the axial movement of the rod12. In the case where the element30is a ram, an end of travel sensor is advantageously used as an end of travel abutment. The device illustrated inFIG.13is advantageously used in the moulding configuration illustrated inFIG.5in which a dose is deposited on the mandrel.

The embodiment illustrated inFIG.14comprises at least one first pressurization element30and one second pressurization element31. This embodiment is advantageously used when the orifice rod12has a long axial stroke. This is the case when the orifice rod12is used to centre the dose in the cavity10during the dosing phase. The first pressurization element30enables the shape endpiece13and the mandrel11to be brought into contact during the closing of the mould. The second pressurization element31enables a high pressure to be exerted at the end of moulding in order to prevent the moulded resin from being inserted between the mandrel11and the shape endpiece13. As the pressure at the end of moulding is high it is necessary to exert a sufficient pressure to prevent blocking the orifice23of the packaging. The first pressurization element30may be a passive element such as a mechanical or pneumatic spring as illustrated inFIG.14. Alternatively, this element may be controlled actively, like a ram. The second pressurization element31is advantageously a short stroke piston as illustrated inFIG.14. A ram of this kind allows easy adjustment of the pressure retaining the orifice rod12as a function of the moulding pressure. Alternatively, this element31may be a passive spring of high stiffness. The device illustrated inFIG.14also comprises a rod exit abutment32that limits the exit stroke of the orifice rod12and a transition abutment33that enables switching from the low pressure exerted by the first pressurization element30to the high pressure exerted by the second pressurization element31. In accordance with the embodiment illustrated inFIG.14, the first pressurization element30is disposed in parallel with the second pressurization element31.

FIG.15illustrates an embodiment similar to that fromFIG.14but in which the first pressurization element30is disposed in series with the second pressurization element31.

FIG.16illustrates an embodiment similar to that fromFIG.15but in which the first pressurization element30and the second pressurization element31are rams the pressure of which can be adjusted.FIG.16illustrates an embodiment in which the first pressurization element30and the second pressurization element31are in series. Another embodiment (not illustrated) may be produced in which the pressurization rams30and31are disposed in parallel.

The embodiments illustrated inFIGS.14,15and16are advantageously associated with the moulding configurations illustrated inFIGS.3,4and6in which the orifice rod is also used to centre the dose during the dosing operation.

The embodiment illustrated inFIG.17is similar to that illustrated inFIG.14but further comprises a bush37used to centre the dose during the dosing operation. The utilization of such a bush37is advantageous when the inside diameter of the dose (which is generally in the shape of a torus) is large compared to the diameter of the orifice rod. The dosing bush is aligned with the cavity of the mould as illustrated inFIG.18. The bush-die alignment abutment36enables this function to be provided. The rod-bush relative position abutments34define the maximum relative movement between the orifice rod32and the bush37. In accordance with the embodiment illustrated inFIG.17, the pressurization elements30and31are disposed in parallel. A similar device (not illustrated) in which the pressurization elements30and31are in series may also be used.

FIG.18illustrates the moulding configuration corresponding to the device illustrated inFIG.17. At the end of moulding the axial position of the bush37is defined by the bush-die alignment at38that enables a head surface to be obtained with no shoulder at the junction of the die10and the bush37.

InFIGS.3to6,7,9and18there have respectively been represented a device for forming a tube head and a tube (that is to say a tube head21attached to a skirt22) but it is obvious that the principle of the present invention applies to the manufacture of a tube head21alone without the skirt and the present invention also covers this aspect of the manufacture of a tube head by compression moulding. The representation of the skirt is therefore a non-limiting embodiment.

The embodiments described are described by way of illustrative examples and must not be considered as limiting on the invention. Other embodiments may call upon means equivalent to those described for example. The embodiments may equally be combined with one another as a function of circumstances or means used in one embodiment may be used in another embodiment.