FR2934519A1 - PROCESS FOR MANUFACTURING A FIRST CONTAINER OF COSMETIC PRODUCT, MOLD, COLLAR AND RECIPIENT - Google Patents

Abstract

This method comprises introducing a deformable material into a mold cavity (106) of a mold (100). The molding cavity (106) has a shape complementary to that of the neck (22) of the first container in a closed position of the mold (100). The mold (100) includes at least one movable core (130) defining an inner indentation (138) for forming the inner thread (58). The method comprises at least partially solidifying the deformable material to form the neck (22), the movable core (130) extending into the introducer passage (56) defined by the sleeve (54) of the coupling skirt (42). It comprises unmolding the neck (22) by forcefully withdrawing the movable core (130) from the insertion passage (56).

Description

A method of manufacturing a first cosmetic container, mold, neck and container associated therewith The present invention relates to a method of manufacturing a neck for a first container of cosmetic product.

Such a neck is adapted to seal a first container containing a first cosmetic product, on which a second container containing a second cosmetic product is intended to be coupled by screwing. For the purposes of the present invention, the term "cosmetic product" is understood to mean a product as defined in Council Directive 93/35 / EEC dated June 14, 1993. Such containers are used in particular for the preparation of cosmetic compositions containing two cosmetics to be mixed just before they are applied to a user. By way of example, the cosmetic composition is an oxidation dye for the hair. In this case, the first cosmetic product is formed by a dye and the second cosmetic product is formed by an oxidant. These products must be stored separately and not mixed until the application of the dye composition on the hair, especially because of the high reactivity of the oxidant.

To facilitate the preparation of the cosmetic composition, it is known to arrange the first cosmetic product in a first large volume container, for example made of plastic, and to place the second most reactive cosmetic product in a compressible metal tube provided at its end. a dispensing tip.

The first container comprises, at its upper end, a neck of the aforementioned type which has a coupling skirt defining an insertion passage of the second container. The skirt is provided with an internal thread protruding into the insertion passage, for screwing the second container. When the user wishes to prepare the cosmetic composition, he takes the second container and screws its tip inside the coupling skirt of the first container. Then, the user compresses the flexible tube constituting the second container, to pass the second cosmetic product contained in the second container to the inner volume defined by the first container.

Then, the user removes the second container, and mounted on the coupling skirt of the first container a dispensing nozzle. Finally, the user mixes the products in the first container, to apply the cosmetic composition to his hair.

A known preparation device is described for example in the French application FR-A-2,685,301. The first container of this device is provided with a neck having a coupling skirt provided with a continuous internal thread for screwing the tube. . It further comprises a peripheral skirt provided with an external thread for screwing a cap on the first container before insertion of the tube. Such a neck is difficult to manufacture by molding, since the internal thread and the external thread present on the neck create parts against undercut making the mold release tedious. It is therefore necessary to provide a complex mold to allow the release of the internal thread, for example by unscrewing a movable core of the mold. However, such a mold is expensive and does not optimize the productivity of the manufacturing process, since the unscrewing of the mobile core increases the cycle time. An object of the invention is therefore to obtain a method of manufacturing a neck for a first container allowing easy coupling with a second container, the method being easy to implement, while allowing the production of the neck to least cost. For this purpose, the invention relates to a method of the aforementioned type, the neck being of the type comprising: - a base wall; a skirt for coupling a second container of cosmetic product to the first container, the coupling skirt comprising: a substantially tubular sleeve defining a passage for introducing a tip of the second container, the introduction passage; extending along an insertion axis; an internal thread for screwing the tip of the second container into the sleeve, the internal thread protruding into the insertion passage towards the insertion axis from the sleeve, the internal thread being of substantially helical shape at least before first screwing a second container into the first container; the method comprising the following steps: introduction of a deformable material into a molding cavity of a mold, the molding cavity having a shape complementary to that of the neck at least in a closed position of the mold, the mold comprising at least one at least one movable core delimiting an internal cavity intended to form the internal thread; at least partial solidification of the deformable material to form the neck, the movable core extending into the introduction passage defined by the sleeve of the coupling skirt; * Release of the neck, comprising the withdrawal force of the movable core out of the introduction passage. The method according to the invention may comprise one or more of the following characteristics, taken separately or in any technically possible combination: the force withdrawal comprises the displacement in translation of the movable core relative to the sleeve along the axis; introduction without rotation about the insertion axis; it comprises, before the introduction step, the arrangement in the mold of a hollow container having an outer edge disposed in the molding cavity, the deformable material coming into contact with the outer edge to assemble the base wall of the collar on the hollow container during the solidification step; and the internal cavity of the mobile core comprises a plurality of disjoint impression regions, the collar having, after the solidification step, an internal thread comprising a plurality of disjoint threads of complementary shape to the disjoint regions, the disjointed threads being angularly spaced apart from each other about the insertion axis. The invention further relates to a mold for the manufacture of a neck for a first container of cosmetic product, the neck being of the type comprising: - a base wall; a coupling skirt of a second container of cosmetic product on the first container, the coupling skirt comprising: a substantially tubular sleeve defining an insertion passage of a tip of the second container, the introducing passage extending along an insertion axis; an internal thread for screwing the tip of the second container into the sleeve, the internal thread protruding into the insertion passage towards the insertion axis from the sleeve, the internal thread being of substantially helical shape at least before first screwing a second container into the first container; the mold being characterized in that it comprises a first half-mold and a second half-mold, movable relative to each other between an open position of the mold and a closed position of the mold, in which the first half-mold and the second half-mold define a molding cavity of complementary shape to the shape of the neck, the first half-mold comprising a movable core delimiting an internal cavity intended to form the internal thread, the core being mobile when demolding the neck relative to at least one of the first half-mold and the second half-mold between a position inserted in the introduction passage of the coupling skirt and a position extracted from the insertion passage of the coupling skirt for forcibly withdrawing the movable core from the introduction passage.

The mold according to the invention may comprise one or more of the following characteristics, taken in isolation or in any technically possible combination: the mobile core is movable in translation along the axis of introduction relative to the sleeve during the unmolding the neck, without rotation about the axis of introduction; and - the inner cavity of the movable core comprises a plurality of disjoint cavity regions for forming on the neck an internal thread comprising a plurality of disjoint threads angularly spaced apart from each other about the insertion axis.

The invention further relates to a neck for a first container of cosmetic product, the neck being of the type comprising: - a base wall; a coupling skirt of a second container of cosmetic product on the first container, the coupling skirt comprising: a substantially tubular sleeve defining an insertion passage of a tip of the second container, the introducing passage extending along an insertion axis; an internal thread for screwing the tip of the second container into the sleeve, the internal thread protruding into the insertion passage towards the insertion axis from the sleeve, the internal thread being of substantially helical shape at least before first screwing a second container into the first container; characterized in that the thread comprises a plurality of disjoint threads spaced angularly from one another about the insertion axis. The collar according to the invention may comprise one or more of the following characteristics, taken separately or in any technically possible combination: the threads delimit between them at least one axial channel which is clear over the entire height of the thread; - It comprises at least one inner stop blocking the screwing of the second container, the or each abutment protruding towards the insertion axis in the introduction passage; - It comprises a plurality of inner locking stops, each inner locking stop being arranged axially opposite a thread of the thread; the or each stop defines a flat portion extending substantially perpendicularly to the insertion axis; and - it comprises a peripheral skirt extending around the coupling skirt, and a connecting wall connecting the peripheral skirt to the coupling skirt, the peripheral skirt having an external thread protruding radially away from the skirt of coupling. The invention also relates to a container for containing a cosmetic product, characterized in that it comprises a hollow container adapted to receive a cosmetic product and a neck as defined above closing the hollow container.

The invention further relates to a device for preparing a cosmetic composition, characterized in that it comprises a first container as defined above, containing a first cosmetic product, and a second container containing a second cosmetic product. and having a tip of complementary shape to the introduction passage, adapted to be screwed into the introduction passage. The invention furthermore relates to a method for preparing a cosmetic composition, characterized in that it comprises the following steps: - providing a preparation device as defined above, the first container containing a first cosmetic product, the second container containing a second cosmetic product; screwing the tip of the second container into the insertion passage of the first container; - Transfer of the second cosmetic product contained in the second container to the first container. The invention will be better understood on reading the following description, given solely by way of example, and with reference to the appended drawings, in which: FIG. 1 is a diagrammatic side view of a first device for preparing a cosmetic product according to the invention comprising two receptacles intended to be coupled; - Figure 2 is a sectional view along a median vertical plane of the neck of a first container of the device of Figure 1, before mounting the second container; - Figure 3 is a top view of the neck of Figure 2; - Figure 4 is a view similar to Figure 2 when coupling the second container on the first container; - Figure 5 is a view of a detail of Figure 4 illustrating the coupling of the second container on the first container; FIG. 6 is a partial perspective view from above of the neck of FIG. 2; - Figure 7 is a partial schematic sectional view along a median vertical plane of the manufacturing mold of the neck of Figure 2, in a first step of the manufacture of the neck; - Figure 8 is a view similar to Figure 7, during a second step of the manufacture of the neck; - Figure 9 is a view similar to Figure 8 during the release force of the neck; and FIG. 10 is a view similar to FIG. 7 after force demolding of the neck.

In all that follows, the terms inside and outside mean in relation to the container and the interior volume that it defines. The lower and upper terms are relative in relation to the arrangement of the containers in the Figures, oriented to permit reading of the reference numbers.

A first device 10 for preparing a cosmetic composition according to the invention is illustrated in FIG. 1. This device comprises a first container 12 containing a first cosmetic product, a second container 14 containing a second cosmetic product intended to be mixed with the first cosmetic product, and an applicator tip 16 of the cosmetic composition on a user, this tip being adapted to be attached by screwing to the end of the first container after mixing the products. The applicator tip has a comb shape and has dispensing orifices of the mixed product. The device 10 further comprises a package 17 for storing the containers 12, 14 and the applicator tip 16. The first cosmetic product and the second cosmetic product are intended to be mixed by the user to form the cosmetic composition in the first container 12 just before the application of this composition to the user.

The composition is, for example, an oxidation dye for hair, the first cosmetic product and the second cosmetic product being respectively a dyestuff and an oxidant.

As illustrated by FIGS. 1 and 2, the first container 12 comprises a hollow container 20, a neck 22 according to the invention, attached to the hollow container 20, and a closure plug 24, screwed onto the neck 22 before coupling the second container 14 on the first container 12.

As illustrated in FIG. 1, the container 20 is of generally cylindrical shape. It has a bottom 26, and a side wall 28 which defines an interior volume 30 opening through an upper opening 32 closed by the neck 22. The container 20 is advantageously made in one piece based on a thermoplastic plastic such as a polyolefin such as high density polyethylene. As illustrated in FIG. 2, the neck 22 comprises a frustoconical base wall 40, a central coupling skirt 42 of the second container 14 on the first container 12, a peripheral skirt 44 for screwing the plug 24, and a frustoconical wall 46 of connection between the coupling skirt 42 and the peripheral skirt 44. The base wall 40 has a section, taken in any median vertical plane such as the sectional plane of the figure, converging externally to the skirts 42, 44 away 20. The wall 40 extends between a peripheral lower edge 50, on which is reported the side wall 28 of the container 20, and an upper edge 52, from which the peripheral skirt 44 projects upwards. In this example, and as will be seen below with reference to FIGS. 7 to 10, the base wall 40, the coupling skirt 42, the peripheral skirt 44, and the connecting wall 46 are made in one piece by molding a thermoplastic material such as a polyolefin such as high density polyethylene. Referring to Figure 2, the central skirt 42 comprises a tubular coupling sleeve 54 defining a central passage 56 for introducing the second container 14, and a discontinuous thread 58 projecting radially in the central passage 56. The sleeve 54 protrudes externally from the base wall 40. The coupling skirt 42 further has, under the thread 58, discontinuous stops 60 of immobilization of the second container 14 in the passage 56.

The sleeve 54 protrudes outwardly along and about the axis of introduction AA 'defined by the passage 56, from the connecting wall 46, above the base wall 40, to an outer edge 61. The outer edge 61 of the sleeve 54 defines an axial notch 61A for introducing air into the passage 56. The notch 61A opens upwards and through the sleeve 54. The axis AA 'of the sleeve 54 and the central passage 56 is in this example coaxial with the central vertical axis of the container 20. Alternatively, these axes are shifted transversely.

The introduction passage 56 opens internally downwards into the internal volume 30 through the opening 32 under the base wall 40. It opens outwardly outwardly from the first container 12. As will be seen below, the passage 56 is intended to receive a tip of the second container 14 during its screwing on the first container 12. When the second container 14 is disposed away from the first container 12, the introduction passage 56 allows the mounting of the applicator tip 16 and the extraction of the cosmetic composition contained in the inner volume 30 of the first container 12.

The thread 58 has a helical shape of axis A-A 'extending angularly over more than one turn about the axis A-A', and advantageously over a turn and a half. The thread 58 is helically formed during the molding of the neck 22, before the first screwing of a second container 14 into the neck 22. In the example illustrated by FIGS. 2, 3, 4 and 6, the threading 58 is batchwise. It thus comprises a plurality of continuous threads 62, angularly spaced apart from each other about the axis AA 'while moving along the general helical path of the thread 58. In this example, the threads 62 delimit between them, by themselves. moving axially along an inner surface of the sleeve 54, axial channels 64 disengaged over the entire height of the thread 58. As illustrated in FIG. 3, the threads 62 project radially towards the axis AA 'from a inner surface of the sleeve 54 defining the introduction passage 56.

The threads 62 are distributed in three disjoint angular sectors a1, a2, a3 about the axis A-A ', visible in FIG. 3. Each thread 62 is separated from an adjacent thread 62 by a longitudinal channel 64. Each thread 62 has an angular extent a1, a2, a3 greater than 15 ° and less than strictly 120 °. In the example shown in the figures, each angular sector a1, a2, a3 about the axis A-A 'comprises two threads 62 arranged one above the other facing one another. Each thread 62 comprises an inclined inner flange, directed towards the inner volume 32. The inner flange has a section, taken in an axial plane passing through the axis A-A ', inclined at an angle of less than 50 ° and approximately equal to at 45 ° with respect to the axis A-A ', to facilitate the demolding force of the neck 22, as will be seen below. The maximum radial extent of each thread 62, taken in the insertion passage 56 from the inner surface of the sleeve 54, perpendicular to the axis A-A ', is less than 20%, advantageously less than 10% of the maximum radial extent of the introduction passage 56, taken perpendicular to the axis AA 'in a threadless region 62. The channels 64 are defined axially between lateral ends of each pair of adjacent threads 62. Each channel 64 extends in an angular sector 131, [32, [33, located about the axis AA 'between two angular sectors a1, a2, a3 containing threads 62. Each channel 64 opens upwards and downwards. It has no undercut parts over the entire height of the thread 58 between the threads 62. Thus, the force release of the neck 22 according to the invention is facilitated by the presence of channels 64 in which no part projects radially towards the axis A-A '. In the example shown in Figures 1 to 6, the neck 22 comprises three immobilizing stops 60 distributed angularly in the angular sectors a1, a2, a3. Each stop 60 is thus situated axially inwardly facing a thread 62.

Each stop 60 comprises a flat portion 66 extending perpendicularly to the axis AA 'along the upper edge 68 of the stop 60, towards a thread 62. The flats 66 project radially towards the axis AA' in the passage 56 to define an immobilizing surface of the tip of the second container 14.

In this example, the flats 66 extend exclusively in the angular sectors a1, a2, a3 containing the threads 62. The longitudinal channels 64 released therefore extend between the flats 66. In addition, as illustrated in FIG. nets 62 extends to a flat 66 on which it is based. This configuration makes it possible to create progressive resistance to screwing the second container 14 into the neck 22 before it is immobilized in the passage 56. The peripheral skirt 44 comprises a peripheral sleeve 69 of axis A-A ', which projects outwardly and upwardly parallel to the axis A-A ', from the upper edge 52 of the base wall 40. The peripheral sleeve 69 extends outwardly around and away from the coupling sleeve 54. The peripheral sleeve 69 has an external thread 70 which protrudes radially away from the axis AA 'from an outer surface of the sleeve 69, to enable the screw 24 to be screwed on. The connecting wall 46 has a section, taken in any median vertical plane, converging towards the container 20. It extends radially between a median portion of the peripheral sleeve 69 and the lower edge of the coupling sleeve 54, over the entire periphery of the sleeves 54, 69 around the ax e A-A '. The connecting wall 46 sealingly seals an annular space 72 defined between the respective sleeves 54, 69 of the skirts 42, 44.

The annular space 72 opens outwardly upwards. The second container 14 is advantageously manufactured based on a metal tube of hardness greater than the hardness of the plastic constituting the neck 22. As illustrated in FIG. 1, the second container 14 comprises a deformable hollow body 80 delimiting an interior volume. 82 for receiving the second cosmetic product. The second container further comprises a coupling end 84 to the first container 12, and a closure cap 86 of the inner volume 82.

In this example, the body 80 is a closed tube along its lower edge and opening exclusively through the nozzle 84. As illustrated in Figure 5, the nozzle 84 is of substantially conjugate shape to that of the introduction passage 56. It has an external thread of complementary shape to the internal thread 58. The operation of the first device 10 according to the invention will now be described. Initially, the first container 12 and the second container 14 are provided, for example in their packaging 17.

The first container 12 contains the first cosmetic product in its interior volume 30. The second container 14 contains, in its interior volume 82, the second cosmetic product intended to be mixed with the first cosmetic product to form the cosmetic composition. To prepare the composition, the user removes the cap 24 of the first container 12 and the cap 86 of the second container 14. It returns the second container 14 and brings its tip 84 into contact with the neck 22 of the first container 12. For this purpose, it introduces the tip 84 of the second container 14 into the insertion passage 56 of the coupling skirt 42 by screwing it into the thread 58. Although the thread 58 is discontinuous to facilitate demolding of the neck 22, the engagement of the tip 84 and its screwing on the threads 62 remains easy and reliable. When the lower edge of the endpiece 84 comes into contact with a flat portion 66 on the upper edge 68 of a stop 60, the screwing of the endpiece 84 of the second container 14 becomes more difficult then stops, the flats 66 forming so a hard point.

The presence of the flats 66 forming a hard point prevents the mechanical deterioration of the thread 58 and its thread portions 62. This configuration avoids the drilling of the thread. In this configuration, shown partially in Figure 5, the inner volume 82 of the second container 14 is connected to the inner volume 30 of the first container through the passage 56 of the neck 22. The user then presses the body 80 to pass the second cosmetic product of the inner volume 82 to the inner volume 30 of the first container.

The presence of the longitudinal channels 64 between the threads 62 of the discontinuous threading 58 allows the evacuation of the air contained in the interior volume 30 of the first container 12, which is removed by the introduction of the second cosmetic product. The flow of the second cosmetic product to the interior volume of the first container through the neck 22 is therefore smooth and easy to control. The presence of the notch 61A on the upper edge 61 of the sleeve 54 further allows the complete escape of air from the first container into the atmosphere during the transfer of the product.

In addition, the important clearance between the neck 22 and the tip of the second container also allows the evacuation of air. When the transfer of product is completed, the user unscrews the second container 14 and mixes the first cosmetic product with the second cosmetic product in the first container 12 by shaking the first container previously closed. Then, when the cosmetic composition is ready, it applies this composition using the applicator tip 16 previously screwed onto the first container. As will be seen below, the presence of a first container 12 equipped with a neck 22 according to the invention facilitates the manufacture of the container 12 and its neck 22, while providing a reliable and easy to use a user. The method of manufacturing the first container 12 according to the invention will now be described, with reference to FIGS. 7 to 10, describing the mold 100 for forming and assembling the neck 22 on the hollow container 20. As illustrated by FIGS. 10, the mold 100 comprises a first half-mold forming a die 102, and a second half-die forming a punch 104 movably mounted relative to the die 102 between an open position of the mold, shown in FIG. 7, and a closed position of the mold, shown in Figure 8. In the closed position, the matrix 102 and the punch 104 delimit between them a molding cavity 106 of complementary shape to that of the neck 22. The matrix 102 comprises a peripheral shell 108 and a central rod 110 comprising a movable core in translation along a central axis BB 'of displacement relative to the outer shell 108.

The shell 108 comprises an upper region 112 delimiting an inner shoulder 114 intended to form the base wall 40, and a lower region 116 delimiting a substantially cylindrical inner surface 118 having an outer imprint 120.

The cylindrical surface 118 is intended to delimit the outer surface of the peripheral skirt 44. The external cavity 120 is of shape conjugated to the shape of the external thread 70 of the peripheral skirt 44. The lower region 108 is made of several mold elements angularly distributed around the axis B-B '. The mold members are radially movable relative to the axis BB 'between a closed configuration, in which the region 108 delimits a continuous peripheral surface 118 in the molding cavity 106, and an open configuration shown in Figure 9 in which the different elements have moved radially away from each other and have deviated from the axis BB 'to allow the release of the external thread 70.

The rod 110 comprises a movable central core 130 intended to form the inner surface of the coupling skirt 42 and a fixed annular sleeve 132 for forming the annular space 72 between the skirts 42, 44. The central core 130 is substantially shaped cylindrical. It has an upper bearing surface 134 on the punch 104, and a peripheral surface 136, of axis B-B ', intended to partially delimit the molding cavity 106 to form the inner surface of the skirt 42. The peripheral surface 136 delimits an internal cavity 138 intended to form the thread 58 and an upper cavity 140 for forming the stops 60 and their flats 66.

The internal cavity 138 is of shape conjugated to that of the thread 58. When the mold 100 is intended to form a neck 22 as illustrated in FIGS. 1 to 6, the impression 138 thus has a plurality of disjoint hollow regions, angularly spaced, of complementary shapes to the different threads 62 of the thread 58.

Alternatively, when the mold 100 is intended to form a neck 22 provided with a continuous thread 58, the internal cavity 138 is formed by a continuous helical cavity extending around the axis B-B '.

The annular liner 132 has an upper projection 142 of shape conjugate to the shape of the annular space 72. The central core 130 is movable along the axis BB 'with respect to the annular liner 132 and with respect to the outer shell 108, between a molded position retracted into the outer shell 108, shown in Figures 7 and 8, to define the molding cavity 106, and an extraction position of the second container 14 out of the mold, shown in Figure 9, wherein the core 130 protrudes externally out of the outer shell 108. The punch 104 is generally cylindrical in shape. It has an outer peripheral surface 150 for supporting the hollow container 20 and a lower sealing surface 152 for the molding cavity 106 disposed opposite the matrix 102. The sealing surface 152 extends substantially transversely with respect to the 'B-B axis'. It comprises a peripheral region 154 of shape conjugate to the inner surface of the base wall 40, and to the inner surface of the connecting wall 46. The sealing surface 152 further has a central region 156 intended to be applied against the upper surface 134 of the core 130 when the punch 104 occupies its closed position of the mold 100.

The molding cavity 106 has a shape substantially conjugate to that of the neck 22 when the punch 104 occupies the closed position of the mold, when the outer shell 108 occupies its closed configuration, and when the core 130 is in its retracted position. The cavity 106 is then delimited by respectively the shoulder 114, the outer surface 118, the upper projection 142 of the annular liner 132, the peripheral surface 136 of the core 130, and the outer region 154 of the lower surface 152 of the punch. In this configuration, the central region 156 of the sealing surface 152 is applied to the upper surface 134. The method of manufacturing the first container 12 comprises a phase of producing the hollow container 20, a forming phase and assembling the collar 22 on the hollow container 20, and a demolding phase in force of the neck 22.

During the production phase of the hollow container 20, the hollow container 20 is manufactured by extrusion of the side wall 28 in the form of a tube and by cutting the tube thus formed. The container 20 is then engaged around the punch 104 to be kept in contact with the outer surface 150. The free outer edge 160 of the side wall 28 projects partially downwards away from the punch 104. Then, during the forming phase and assembly, the punch 104 is brought facing the die 102 in the open position of the mold 100. A dose 158 of partially melted plastic material, capable of being deformed, is introduced between the punch 104 and the matrix 102 in the cavity defined by the outer region 112 of the shell 108 above the rod 110. The dose 158 forms a rod. In this configuration, the core 130 occupies its retracted position. Then, the punch 140 is approached from the die 102 to the closed position of the mold 100. In this position, the mold 100 delimits, as we saw above, a molding cavity 106 of shape complementary to that of the neck 22. The upper edge 160 of the side wall 28 then protrudes into the molding cavity 106.

During this displacement, the dose 158 introduced into the matrix 102 is deformed and fills the molding cavity 106 to form the neck 22 and assemble it on the outer edge 160 of the wall 28. Then, the molten plastic contained in the The cavity 106 at least partially solidifies, for example by cooling the punch 104 and the die 102. The skirts 44, 46 provided with their respective threads 58, 70 are then formed. The core 130 is disposed in the insertion passage 56 of the coupling skirt 42 with its axis B-B 'of displacement coinciding with the axis A-A' of the passage 56. The upper projection 142 occupies the annular space 72.

During the demolding phase, the mold elements of the lower region 116 of the outer shell 108 then open radially towards the open configuration illustrated in FIG. 9, to disengage the external thread 70 and allow it to be extracted from the die 102.

The punch 104 is pulled out of the container 20. The core 130 has then moved from its retracted position to its deployed position, as shown in FIG. 9. This moves the neck 22 and the container 20 upwards away from the During this movement, the upper projection 142 leaves the annular space 72 between the skirts 42, 44, which is then disengaged. Then, in the force demolding step, the container 20 and the neck 22 are held stationary along the axis B-B 'by a holding means (not shown). The core 130 is moved again along the axis BB 'to its retracted position in the die 102, causing its force extraction out of the insertion passage 56 from the connecting wall 46 to the outer edge 61, to unmold the internal thread 58. The inclined shape of the inner pan of the or each thread 62, the dimensions, and if necessary, the discontinuities of the thread 58 facilitate this demolding force. In addition, the sleeve 54 of the coupling skirt 42 deforms radially in the annular space 72 to promote the passage of the core 130 between the or each thread 62 of the thread 58. During demolding, the relative movement of the central core 130 relative to at the coupling skirt 42 is a translation movement along the axis AA 'without rotation about this axis A-A', which allows rapid demolding using a mold 100 little complex and therefore little expensive to make. The first container 12 is then detached from the mold and the production of another container can be started, with a very short cycle time. The method described above, comprising a step of force release of the internal thread 58, is implemented indifferently to manufacture collars 22 provided with a discontinuous internal thread 58 as shown in Figures 1 to 6, or collars 22 provided with a continuous internal thread 58 comprising a single continuous thread 62. The neck 22 is thus manufactured in one piece in a simple and inexpensive manner, in a manner suitable for mass production.

Claims (1)

CLAIMS 1. A method of manufacturing a neck (22) for a first container (12) of cosmetic product, the neck (22) being of the type comprising: a base wall (40); a skirt (42) for coupling a second container (14) of cosmetic product to the first container (12), the coupling skirt (42) comprising: a substantially tubular sleeve (54) defining a passage (56) introducing a tip (84) of the second container (14), the introducing passage (56) extending along an insertion axis (A-A '); an internal thread (58) for screwing the end piece (84) of the second container (14) into the sleeve (54), the internal thread (58) projecting into the insertion passage (56) towards the axis d introducing (A-A ') from the sleeve (54), the internal thread (58) being of substantially helical shape at least before the first screwing of a second container (14) into the first container (12); the method comprising the steps of: introducing a deformable material into a mold cavity (106) of a mold (100), the mold cavity (106) having a shape complementary to that of the neck (22) at least in a closed position of the mold (100), the mold (100) comprising at least one movable core (130) defining an internal cavity (138) for forming the internal thread (58); at least partial solidification of the deformable material to form the neck (22), the movable core (130) extending in the insertion passage (56) defined by the sleeve (54) of the coupling skirt (42) ; demolding of the neck (22), comprising forcibly removing the movable core (130) from the introduction passage (56). 2. A method according to claim 1, characterized in that the force withdrawal comprises the displacement in translation of the movable core (130) relative to the sleeve (54) along the insertion axis (A-A '). without rotation about the insertion axis (A-A '). 3. A process according to one of claims 1 or 2, characterized in that it comprises, before the introduction step, the arrangement in the mold (100) of a hollow container (20) having an outer edge (160) disposed in the mold cavity (106), the deformable material contacting the outer edge (160) to assemble the base wall (40) of the neck (22) on the hollow container (20) when the step of solidification. 4. A method according to any one of the preceding claims, characterized in that the inner cavity (138) of the movable core (130) comprises a plurality of disjoint impression regions, the neck (22) having, after the solidification step, an internal thread (58) comprising a plurality of disjoint threads (62) of complementary shape to the disjoint regions, the disjoint threads (62) being spaced apart angularly from each other about the insertion axis (A- AT'). 5. Mold (100) for the manufacture of a neck (22) for a first container (12) of cosmetic product, the neck (22) being of the type comprising: - a base wall (40); a skirt (42) for coupling a second container (14) of cosmetic product to the first container (12), the coupling skirt (42) comprising: a substantially tubular sleeve (54) defining a passage (56) introducing a tip (84) of the second container (14), the introducing passage (56) extending along an insertion axis (A-A '); an internal thread (58) for screwing the end piece (84) of the second container (14) into the sleeve (54), the internal thread (58) projecting into the insertion passage (56) towards the axis d introduction (A-A ') from the sleeve (54), the internal thread (58) being of substantially helical shape at least before the first screwing of a second container (14) into the first container (12), the mold (100) being characterized in that it comprises a first half-mold (102) and a second half-mold (104), movable relative to each other between a mold opening position (100) and a mold closing position (100), wherein the first half-mold (102) and the second half-mold (104) define a mold cavity (106) of complementary shape to the neck (22) , the first half-mold (102) comprising a movable core (130) delimiting an internal cavity (138) for forming the internal thread (58), the core (130) both movable when demolding the neck (22) relative to at least one of the first half-mold (102) and the second half-mold (104) between a position inserted in the insertion passage (56) of the coupling skirt (42) and a position extracted from the insertion passage (56) of the coupling skirt (42) for forcibly withdrawing the movable core (130) from the insertion passage (56). 6. Mold (100) according to claim 5, characterized in that the movable core (130) is displaceable in translation along the insertion axis (A-A ') relative to the sleeve (54) during the demolding of the neck (22), without rotation about the axis of introduction (A-A '). 7. Mold (100) according to any one of the preceding claims, characterized in that the inner cavity (138) of the movable core (130) comprises a plurality of disjoint impression regions, intended to form on the neck ( 22) an internal thread (58) comprising a plurality of disjoint threads (62) spaced angularly from each other about the insertion axis (A-A '). 8. Col (22) for a first container (12) of cosmetic product, the neck (22) being of the type comprising: - a base wall (40); a skirt (42) for coupling a second cosmetic container (14) to the first container (12), the coupling skirt (42) comprising: a substantially tubular sleeve (54) defining an introduction passage ( 56) of a nozzle (84) of the second container (14), the introducing passage (56) extending along an insertion axis (A-A '); an internal thread (58) for screwing the end piece (84) of the second container (14) into the sleeve (56), the internal thread (58) protruding into the insertion passage (56) towards the axis d introducing (A-A ') from the sleeve (56), the internal thread (58) being of substantially helical shape at least before the first screwing of a second container (14) into the first container (12); characterized in that the thread (58) comprises a plurality of disjoint threads (62) spaced angularly from one another about the insertion axis (A-A '). 9. Col (22) according to claim 8, characterized in that the threads (62) define between them at least one axial channel (64) clear over the entire height of the thread (58). 10. Col (22) according to any one of claims 8 to 9, characterized in that it comprises at least one inner stop (60) for locking the screwing second tier (14), the or each stop (60) protruding towards the insertion axis (A-A ') in the insertion passage (56). 11. Col (22) according to claim 10, characterized in that it comprises a plurality of stops (60) inner locking, each stop (60) inner blocking being arranged axially opposite a thread (62) threading (58). 12. Col (22) according to any one of claims 10 or 11, characterized in that the or each abutment (60) defines a flat (66) extending substantially perpendicularly to the axis of introduction (A- AT'). 13.- neck (22) according to any one of claims 8 to 12, characterized in that it comprises a peripheral skirt (44) extending around the coupling skirt (42), and a connecting wall ( 46) connecting the peripheral skirt (44) to the coupling skirt (42), the peripheral skirt (44) having an external thread (70) projecting radially away from the coupling skirt (42). 14.- Container (12) intended to contain a cosmetic product, characterized in that it comprises a hollow container (20) adapted to receive a cosmetic product and a neck (22) according to any one of claims 8 to 12 shut off the hollow container (20). 15.- Device (10) for preparing a cosmetic composition, characterized in that it comprises a first container (12) according to claim 14, containing a first cosmetic product, and a second container (14) containing a second product. cosmetic and having a tip (84) of complementary shape to the insertion passage (56), adapted to be screwed into the insertion passage (56). 16. A process for preparing a cosmetic composition, characterized in that it comprises the following steps: - providing a preparation device (10) according to claim 15, the first container (12) containing a first cosmetic product the second container (14) containing a second cosmetic product; - Screwing the tip (84) of the second container (14) into the introduction passage (56) of the first container (12); - Transfer of the second cosmetic product contained in the second container (14) to the first container (12).