Concentric mold cooling

Abstract

Title: Concentric mold cooling The present invention relates to a device (1) for molding a container (2) from a preform (3), said device (1) comprising a base (4) and having a central axis (5), said base (4) having a bottom (6), generally centered on the central axis (5) and in which is arranged an imprint (7) against which said preform (3) can be pressed so as to create the base (8) of said container (2), said bottom (6) having an external periphery (9) and comprising a pipe (10) which extends generally transversely to said central axis (5) between the latter and the periphery (9) to circulate therein a temperature control fluid of said device (1).This device is characterized in that the pipe (10) has a first portion (11), which, on the one hand, has a first inlet zone (12) offset from the central axis (5) to receive the fluid and an arc distant from said central axis (5) which follows it, and which, on the other hand, causes said fluid to flow, preferably after said arc, approaching said central axis (5). The invention also relates to an implementation method. Figure for abstract: Fig.1.

Description

Title of the invention: Concentric mold cooling

[0001] Technical field: The present invention relates to the field of blowing plastic containers, particularly PET, polyethylene terephthalate, more particularly from a smaller blank, or preform, which is subjected to expansion within a mold, by the injection of pressurized gas until it takes the shape of a hollow impression provided within the mold. The subject of the invention is a device and a method for manufacturing containers by blow molding.

[0002] State of the art: In the field of container blowing within a mold, it is necessary to control the temperature of said mold. Indeed, the preforms being heated in order to allow their transformation, they transmit to the blow mold a part of their thermal calories. Without evacuation of these calories from the mold, the latter would continue to heat at each blow cycle until reaching a temperature which prevents production, in particular because of prohibitive production defects, such as deformation. It is then necessary to provide a circulation of a cooling liquid within the mold, an exchanger generally being provided to release again the calories from the mold absorbed by the liquid.

[0003] The cooling circuits within the mold are generally dug at least in the bottom of the mold.

[0004] Conventionally, the preform is in the form of a circular cylindrical tube, with, at one end, an open portion with a neck, and, at the other end, a closure which has a generally half-sphere shape. This half-sphere part is therefore stretched to contribute to forming the bottom of the bottle, by pressing against the imprint that the mold base has at this location. Prior to the blowing step, the preform was manufactured by injection and, at the external end of this half-sphere, it generally has the trace of the injection point.

[0005] Patent US7025584 discloses the implementation of a conventional cooling principle, namely the arrangement of a flow circuit in the bottom of the mold. More particularly, this patent proposes, for petaloid bottoms, therefore with humped feet separated by hollow valleys, a circuit which follows the surface of the valleys more closely, thanks to hollow sections elongated in the axial direction, and partitions judiciously arranged in the middle in these longitudinal hollow sections.

[0006] Publication CN202037856 illustrates a coil in the form of a diverging spiral. The coolant enters the base of the mold from the peripheral surface of said base, and also leaves the base at this surface. The coolant enters the cooling pipe at the part central and gradually moves out to the periphery of the mold.

[0007] Finally, CN203381178 discloses a cooling pipe obtained by providing walls in the form of ribs spaced apart from each other.

[0008] Given the thickness and stretching of the central area of ​​the preform, as well as its importance in the mechanical strength of the container subsequently obtained, cooling in the mold of this area is particularly important.

[0009] The invention aims to improve the cooling of the mold base and more particularly to improve the cooling of the base of the container obtained, to improve the mechanical strength of the container obtained and possibly increase production rates.

[0010] Disclosure of the invention: The invention thus provides a molding device and a corresponding method, which better distributes the cooling of the base of the container. To do this, it is proposed that the cooling begins at a crown around the central axis of the mold, continues convergently towards said center, then, after this cooling of the central part, continues with the part beyond said crown, preferably divergently, i.e. towards the periphery of the mold.

[0011] In doing so, by avoiding heating of the cooling liquid which would be caused by an initial circulation near the imprint and towards the central axis, it is ensured that the cooling is maximum, because obtained by the liquid at the beginning of its cycle under the imprint, at the level of this crown zone. The liquid therefore begins its cooling action by circulating at a distance from the central axis, between the central axis and the periphery, along a complete or almost complete crown, then gradually approaches the central axis, then, in a second stage, acts in the part between said crown and the periphery. The cooling power therefore decreases from a crown around the central axis, to the center, then from this crown to the periphery, following a pipe path of corresponding shape.

[0012] Thus, in accordance with the invention, it is proposed to organize, in the bottom of the mold, by means of an appropriate pipe, a circulation of the liquid first from an intermediate zone towards the center of the mold, then between the intermediate zone and the periphery of the mold. Thus, the most intense cooling takes place in an intermediate zone, around and at a distance from the center of the mold, where the top of the preform normally arrives, namely its injection point.

[0013] The invention thus relates to a device for molding a container from a preform, said device comprising a base and having a central axis, said base having a bottom, generally centered on the central axis and in which is arranged a imprint against which said preform can be pressed so as to create the base of said container, said bottom having an external periphery and comprising a pipe which extends generally transversely to said central axis between the latter and the periphery to circulate therein a temperature control fluid of said device.

[0014] The pipe 10 extends generally transversely to the central axis 5 at a distance that is sufficiently small to have a significant thermal effect. In the case of a container bottom that is significantly non-flat, the pipe 10 may at least partially follow the profile of the imprint 7 and therefore have parts that are slightly offset from each other along the central axis 5. Overall, the pipe 10 extends within the bottom 6 between two planes perpendicular to the central axis 5 which allow the fluid circulating therein to fulfill its thermal regulation function. Conventionally, the plane furthest from the imprint 7 is approximately five millimeters away from it, while the plane closest to the imprint 7 is approximately two millimeters away from it.

[0015] According to the invention, the pipe 10 has a first portion 11, which, on the one hand, has a first inlet zone 12 offset from the central axis 5 to receive the fluid and an arc distant from said central axis 5 which follows it, and which, on the other hand, causes said fluid to flow, preferably after said arc, approaching said central axis 5, so that the cooling effect is greater at a ring around the central axis 5 than at the central axis 5 itself. The first inlet zone 12 forms the arrival of the cooling liquid in the zone where the cooling takes place, and is located less than approximately four centimeters from the central axis 5, preferably less than three centimeters. The arc in which the fluid then circulates from the start of its action extends over at least three-quarters of a turn or even a full turn, before the part of the pipe 10 which brings the fluid closer to the central axis 5.This arc, which may be an arc of a circle or of a different profile, therefore ensures a first cooling at the level of a crown around the central axis 5, or at least a part of such a crown which represents a significant angular range, of the order of at least half a turn, and preferably at least three-quarters of a turn. It is only after having circulated in this first part around and at a distance from the central axis 5, and thus exerted a first cooling effect on a periphery around and at a distance from the central axis 5, that the pipe 10 directs the fluid towards the central axis 5.

[0016] The first portion 11, where the cooling action of the cooling liquid begins, is therefore convergent towards the central axis 5, after a first part which goes all the way around or at least three-quarters of a turn, at a distance from the central axis 5.

[0017] According to a possible additional characteristic, the pipe 10 has a second portion 13, located between the first portion 11 and the periphery 9, downstream of the first portion 11, so that the fluid flows first in the first portion 11, then in the second portion 13, which makes it possible to provide cooling of the base beyond the crown delimiting the first portion 11. As will be further described later, the second portion 13 is located after the first portion 11 in the direction of flow of the fluid. The second portion 13 therefore extends between the crown within which the first portion 11 is located and the periphery 9 of the bottom 6, that is to say the external surface of the bottom, of essentially cylindrical shape.

[0018] The first portion 11 and the second portion 13 may be in the same plane perpendicular to the central axis 5, or slightly offset, for example if the base of the bottle is not flat.

[0019] According to another possible additional characteristic, the base 4 comprises a distributor 14, arranged against the bottom 6 at the central axis 5 and provided therein with a passage 15 for said fluid, said passage 15 having an inlet mouth 16 for receiving fluid which leaves the first portion 11, and an outlet mouth 17 for supplying the fluid to the second portion 13, in particular at the second inlet zone 19 of the second portion 13 which makes it possible to bring the cooling fluid from the downstream end of the first portion 11 to the upstream end of the second portion 13, further from the central axis 5, with a simple construction. The distributor is thus received in a housing provided for this purpose in the bottom 6 and / or the cover 20. More precisely, the first and second portions, in the form of a groove, create walls between them at the bottom 6.The cover comes into contact with a part of these walls, another part of these walls coming into contact with the distributor at the level of one of these faces, its other face being taken in the cover.

[0020] As will be described later, this circulation moving away from the central axis 5 to beyond the crown where the pipe 10 provides the first cooling, can take place in a plane further from the imprint than that where the first portion 11 of the pipe 10 is located.

[0021] The inlet mouth 16 is therefore located in particular at the central axis 5, opposite the first outlet zone which forms the outlet end of the first portion 11, the fluid passing from the first portion 11 to the distributor in a movement along the central axis 5, the outlet mouth 17 is in particular offset relative to the central axis 5 and distant from it, opposite the second inlet zone 19 from which the fluid circulates in the second portion 13, the circulation of the fluid at the outlet mouth 17 and the second inlet zone 19 taking place generally transversely to the central axis 5.

[0022] The base 4 thus notably takes the form of a stack obtained by, successively, the cover 20, the distributor 14 and the bottom 6.

[0023] According to another possible additional characteristic, the distributor 14 has an axial orifice 18 extending at least partially along the central axis 5, and offset from the latter, said axial orifice 18 opening at the level of the first inlet zone 12 to bring the fluid into the first portion 11, which makes it possible to bring the cooling fluid to the start of the pipe 10. This axial orifice 18 is close to the central axis 5, but slightly distant, and ends at the level of the crown which delimits an interior part cooled after the exterior part.

[0024] According to another possible additional characteristic, the second portion 13, on the one hand, has a second inlet zone 19 at which it receives the fluid, and, on the other hand, causes it to flow away from the central axis 5 in the direction of the periphery 9, which makes it possible to cool the part of the impression 7 which molds, for example, the feet of a petaloid base.

[0025] According to another possible additional characteristic, the base 4 comprises a cover 20 in which a path 22 is arranged to bring the fluid towards the pipe 10 by moving it at least partially in the direction of the central axis 5 from an entry point 21, the pipe 10 taking for example the form of a groove hollowed out in the base 4, which the cover 20 closes. The path 22 opens for example at the axial orifice 18 of the distributor 14. If necessary, as shown in Figures 2 and 8, the cover 20 also comprises a discharge channel 23 which is in communication, on the one hand, with the outlet of the pipe 10 to receive the fluid therefrom, and, on the other hand, with the outside of the base 4 to send the liquid out of the molding device. The cover 20 has generally the shape of a cylinder of revolution.

[0026] According to another possible additional characteristic, the molding device 1 further comprises lateral shells which extend along the central axis 5, against which the preform 3 can be pressed so as to create the sides of the container 2 during blowing, which makes it possible to form the final packaging. The arrangement 1 thus comprises not only the base 4 which will define the base of the container 2, but also at least one and preferably two lateral shells, which come opposite each other during blowing, to define the sides of the container 2.

[0027] The invention also relates to a method which implements the device described above. The invention thus relates to a method for manufacturing a plastic container 2 by blowing a preform 3, in which the preform 3 is placed in a molding device 1 having a central axis 5 and comprising a base 4 having a bottom 6, then a pressurized gas is injected into the preform 3 so that it matches the internal contour of said molding device 1 until a container 2 is formed, the method further comprising controlling the temperature of the molding device 1 using a fluid.

[0028] According to the invention, the control The temperature control is achieved by circulating a fluid in the molding device 1 at the base 4, and this along a path generally transverse to the central axis 5, starting, in a first phase, at the level of a crown around the central axis 5, at a distance from the latter as well as from the external surface of the base 4, the fluid for example then moving towards or away from the central axis 5.

[0029] This crown delimits a part which is internal to it, comprising the central axis 5 and a part which is external to it, with the periphery 9. The cooling begins at the level of this crown, then continues in the internal part by approaching the central axis 5 preferably without moving away from it again, then continues from this crown but then in the direction of the periphery 9, therefore in the external part, after a communication between the two parts which takes place in an offset plane, preferably further from the imprint 9 than the first portion 11 of the pipe 10 which extends for the internal part and the second portion 13 of the pipe 10 which extends for the external part.

[0030] According to a possible characteristic of the method, the preform 3 has a top 24, and is placed in the molding device 1 so that its top 24, after stretch blow molding, is generally at the level of the central axis 5, in such a way that the most powerful cooling, that is to say when the fluid is at the start of its circulation in the base 4, takes place not at the level of the top 24 of the preform 3, but at the level of a crown or portion of crown which surrounds the top 24.Unlike usual cooling techniques, the cooling fluid is therefore not heated when it approaches the imprint 7 by advancing along the central axis 5 to the pipe 10, the cooling does not begin with the tip or apex 24 of the preform, therefore the center of the container 2 to gradually move away from it, nor with the periphery 9 to move closer to the central axis 5, but begins with a central crown, before any convergence towards the central axis 5. In the first portion 11, the fluid remains at a distance from the central axis 5 then approaches it, and does not move away from it.

[0031] According to a possible characteristic of the method after the first phase of circulation of the fluid in the base 4, the fluid circulates while approaching the central axis 5. Thus, after the first phase during which the fluid acts on a ring distant from the central axis 5, the latter is sent progressively to the level of the central axis 5. The cooling effect is therefore the most important, because it is the first zone of effective heat exchange, at the level of a ring, then in the direction of the center, therefore of the central axis 5. This circumferential then convergent circulation in the first portion 11 takes place close to the imprint 7, that is to say in particular closer to the imprint than the communication between the first and the second portion.

[0032] According to a possible characteristic of the method, the circulation of the fluid in the base 4 comprises a phase subsequent to the first phase, during which the fluid circulates away from the central axis 5 from beyond the crown, in particular up to the periphery 9 of the base 4. The fluid then circulates in the second portion 13 of the pipe, from the second inlet zone, and moves away from the central axis 5, generally perpendicular to it. The second portion 13 of the pipe 10 can take the form of a spiral traversed in a divergent direction, or simply successive arcs of a circle, joined by radial sections.

[0033] Brief description of the drawings: Other advantages and characteristics will emerge more clearly from the following description of a single variant embodiment, given as a non-limiting example, of the device according to the invention, with reference to the appended drawings in which: [Fig.l] shows a sectional view of the molding device, with the stack of the cover, the distributor and the base [Fig.2] illustrates the cover and the distributor housed therein [Fig.3] represents a section showing the cover and the distributor [Fig.4] shows, in section, the stacking of the bottom, the distributor and the cover, in a plane offset from the main axis [Fig.5] shows the pipeline as dug in the bottom of the base, with two separate portions [Fig.6] shows the pipeline as dug, with the distributor in its operating position [Fig.7] shows the distributor within the cover, including the groove which allows the fluid to pass from the distributor to the second portion of the pipe. [Fig.8] shows a section from a plane perpendicular to the main axis, at the level of the ribs which delimit the pipeline, with the distributor taken between them and the cover [Fig.9] shows a preform [Fig. 10] shows a container [Fig. 11] shows a spiral profile [Fig. 12] shows a spiral profile for the distributor

[0034] Embodiment of the invention:

[0035] The molding device 1 according to the invention is used to receive preforms 3 into which a fluid under pressure is injected so as to press them against the imprint 7 presented by said molding device 1. This molding device 1 comprises at least one base 4, which is used to form the normally lower part of the future container 2, in other words its bottom, thanks to which the container 2 then rests ver- tically on a horizontal surface.

[0036] The molding device 1 may also comprise lateral shells, which will form the lateral surfaces of the container 2. The molding device 1 is therefore at least a mold base but may comprise other elements which make it a complete blow mold.

[0037] In any case, the molding device 1 has a central axis 5, which in fact corresponds to the axis along which the container 2 that it forms extends; furthermore, the preform 3 is aligned around this central axis 5 within the molding device 1. The molding device 1 generally has a cylindrical shape around this central axis 5, with a length, as mentioned, which obviously depends on the other components that it may possibly comprise.

[0038] The molding device 1 therefore comprises a base 4, in the extension of which the shells can come, if necessary.

[0039] This base 4 has a stack, along the central axis 5, of a bottom 6, against which the preform 3 will come, and, against this bottom, on the other side, of a cover 20. The bottom 6, which, at its external periphery 9, has a generally cylindrical circumference of revolution around the central axis 5, carries the impression surface 7 to create the shape of the container 2. On the side opposite the impression 7, the bottom 6 has a channel 10, for example in the form of at least one groove. [Fig. 5] shows this part of the bottom 6 with a channel 10 made of two grooves, each in one piece. It is of course possible to imagine more than two separate grooves.The at least one groove, and therefore the pipe 10, has a shape composed, on the one hand, of circular arcs centered on the central axis 5 and having a radius specific to them, and, on the other hand, of straight portions, perpendicular to the central axis 5 and making it possible to join the arc of a first radius to the arc of a second radius. It would also be possible to envisage a pipe 10 with at least one spiral, namely a profile whose distance from the central axis 5 changes over a circumference less than or even greater than a complete turn.

[0040] The pipe 10, in general, is arranged essentially perpendicular to the central axis 5, its function being to receive a cooling fluid, which makes it possible to regulate the temperature of the molding device 1 at this location, by absorbing the thermal calories of the preform 3, previously heated to facilitate its shaping.

[0041] The pipe 10 of the bottom 6, in particular when it is produced in the form of at least one groove, has a rear part, which is therefore the part close to the imprint 7, the position of this rear part along the central axis 5 being able to generally follow the shape of the imprint 7, to maximize the heat exchange.

[0042] The pipeline in the form of at least one groove naturally has walls between the successive sections of groove, in the form of ribs complementary to the grooves, and the cover 20 comes against the end of at least part of these ribs, so as to contribute to thus closing the pipe 10 in a hermetic manner.

[0043] The cover 20 makes it possible, among other things, to bring the fluid which will then have to cool the bottom 6, and therefore to bring the fluid into the pipe 10 which the bottom 6 has. It also possibly makes it possible to evacuate the fluid after it has circulated in the pipe 10. The cover 20 receives the cooling fluid from an element not shown, which is located beyond the cover 20 in the stacking sequence bottom 6 then cover 20 along the central axis 5. A movement of the cooling liquid to be sent into the pipe 10 of the bottom 6 is therefore arranged within the cover 20. For this purpose the cover 20 has a path 22 for circulating the cooling liquid in the direction of the bottom 6, and this path 22 is located near the central part of the molding device 1, that is to say that the path 22 remains less than 5 centimeters from the central axis 5, preferably less than 3 centimeters.This makes it possible in particular to ensure that the liquid entering the bottom 6 does so close to the center, namely the central axis 5, possibly only slightly offset from it as described later, so as to cool more intensely the generally central part of the bottom 6 rather than the part close to the periphery 9, which is the case when the fluid arrives in the bottom 6 close to the periphery 9.

[0044] [Fig. 3] shows the path 22 within the cover 20, with a portion aligned with the central axis 5. This embodiment also illustrates the possibility of a break in the path 22 perpendicular to the central axis 5, then a following section again parallel to the central axis 5, offset relative to this axis. In practice, this break is obtained by drilling from an edge of the device, therefore from the periphery 9, until reaching the portion of the path 22 which is aligned with the central axis 5 and going beyond it to form said break. It is understood that the part of the drilling on the other side of the central axis 5 relative to the step is not used for the circulation of fluid towards the bottom 6, but forms a dead end in the path of the fluid, and is therefore not part of the path 22. In general, the parts of drillings used to create said path 22 but in which the fluid cannot circulate because they form a dead end are not part of the path 22..

[0045] In the embodiment illustrated here, the molding device 1 also comprises a distributor 14. This distributor 14 is mounted sandwiched between, on one side, the bottom 6, and, on the other, the cover 20. As will be explained, this distributor 14 participates in bringing the fluid from the path 22 of the cover 22 into the pipe 10 of the bottom 6 as well as in bringing the fluid between different successive portions of said pipe 10.

[0046] The distributor 14 generally has the shape of a disc or pellet, and is positioned at level of the central axis 5, between the bottom 6 and the cover 20. It allows, on the one hand, to conduct the incoming liquid into the pipe 10, and, on the other hand, to connect two successive portions of the pipe 10 together.

[0047] More precisely, as shown in [Fig. 3] in particular, in one possible embodiment, the distributor 14 has an axial orifice 18, which extends parallel to the central axis 5 but at a distance from it. This axial orifice 18 is located opposite the outlet mouth of the path 22 dug in the cover 20 for the circulation of the liquid towards the pipe 10. This axial orifice 18 is therefore also close to the central axis 5, less than approximately 3 centimeters, and contributes to bringing the incoming liquid as close as possible to the impression 7 thanks to a flow essentially parallel to the central axis 5. This axial orifice 18 allows the cooling liquid to pass through the distributor 14 in the direction of the central axis 5 so that the cooling liquid begins its cooling action close to the central axis 5 but slightly offset from the latter, that is to say closer to the central axis 5 than to the periphery 9.

[0048] The distributor 14 also comprises a passage 15, for circulating the liquid, more particularly from an inlet mouth 16 of said passage 15 which is located at the level of the central axis 5, and to an outlet mouth 17 of said passage 15 which is located away from the central axis 5, see [Fig. 6]. This passage 15 makes it possible to put two successive portions of the pipe 10 into fluid communication, as will be described later. The inlet mouth 16 communicates with the downstream end of a first portion 11 of the pipe 10, by simply being located opposite each other, and the outlet mouth 17 communicates with the upstream end of a second portion 13 of the pipe 10, again by simply being opposite each other.

[0049] The circulation of the fluid is therefore carried out in the following way.

[0050] The fluid is initially received by the cover 20 at the central axis 5, more precisely at the level of a passage hole that the path 22 has which is dug there, see [Fig.3]. This path 22, which allows the fluid to circulate within the cover 20 towards the bottom 6, extends less than 3 centimeters from the central axis 5, which makes it possible to increase the cooling effect at the level of the part of a central disc. Indeed, this path 22 emerges from the cover 20 while being slightly distant from the central axis 5. The fluid thus circulates in this path 22 and leaves the cover 20 without having moved away from the central axis 5 by more than 3 centimeters, or at least by at most 5 centimeters. The fluid then continues into the axial orifice 18 presented by the distributor 14, said orifice being in the extension of the downstream end of the path 22, parallel to the central axis 5.The fluid initially received in the cover 20 in an area close to the central axis 5 therefore advances along the central axis 5, first crossing the path 22 dug in said cover 20 then the axial orifice 18, all closer but not confused with. the central axis 5 than the periphery 9.

[0051] The axial orifice 18 of the distributor 14 is slightly offset from the central axis 5, to bring the fluid into the pipe 10 at the level of a crown which it presents around the central axis 5.

[0052] Thus, after passing through the axial orifice 18, the fluid continues in a first portion 11 of the pipe 10, to begin its function of cooling the cavity 7. The pipe 10, which extends generally perpendicular to the central axis 5, therefore has an entry point for the incoming fluid which is slightly offset from the central axis 5. This entry point forms a first entry zone 12 for a first portion 11 of the pipe 10, see [Fig. 5]. Once brought by the cover 20 then the distributor 14, the fluid therefore arrives in the cooling pipe 10 slightly away from the central axis 5. The fluid therefore then circulates perpendicular to the central axis 5 in the first portion 11, which begins away from the central axis 5 and ends closer to the central axis 5, preferably at the central axis 5. As shown in [Fig.5], the first portion 11 extends over at least 180 degrees, and preferably comprises an arc of a circle which extends over at least half a turn, or even at least three-quarters of a turn. This arc of a circle may be followed by a radial linear part to bring the fluid to the central axis 5. It is of course possible to envisage a more sophisticated shape for the first portion 11, such as for example a spiral shape, or even several arcs of a circle whose radii are different for each, the arcs being connected by radial parts, etc. It can be seen that the first portion 11 is such that the fluid circulates therein from an area eccentric with respect to the central axis 5 and gradually approaches said central axis 5. It can be envisaged that the end of the first portion 11 is at the level of the central axis 5, as in [Fig.5], in which case the first portion 11 extends over all or part of a disc centered on the central axis 5; it is also possible to envisage that the end of the first portion 11 is also far from the central axis 5, however closer to it than the first inlet zone 12, in which case the first portion 11 extends over all or part of a ring centered on the central axis 5. The first portion 11 preferably extends over 360 degrees, and, at a minimum, extends over three-quarters of a turn or even at least half a turn, and this preferably before approaching the central axis 5. This makes it possible to organize the most powerful cooling, that is to say the first, at the level of a ring progressively concentric around the central axis 5.

[0053] In the embodiment illustrated in Figures 5 and 6, once the fluid has completed its circulation around the central axis 5, converging towards it, in the first portion 11, it will be redirected further from the central axis 5 than is the first inlet zone 12. The fluid then circulates in the distributor 14, within the passage 15 which begins at the level of the central axis 5 with the inlet mouth 16, moves away from the imprint 7 through a hole along the central axis 5, then continues in a divergent part, visible in [Fig.6]. This divergent part begins with a radial section, then an arcuate section, then a section which opens onto the external surface of the distributor 14, for example the lateral surface. The passage 15, which arranges the circulation of the fluid within the distributor 14, therefore contains a part which extends perpendicular to the central axis 5, which allows the fluid to be moved away from the central axis 5 and which is further from the imprint 7 than the part of the first portion 11 which brings the fluid closer to the central axis 5. These two parts are at the level of the central axis 5, but offset from each other along this axis.The passage 15 therefore comprises a channel diverging from the central axis 5, at a distance from the imprint, while the pipe comprises a channel converging towards the central axis 5, closer to the imprint, these two channels being in different planes perpendicular to the central axis 5, so that the convergent is closer to the imprint 7 than the divergent.

[0054] The fluid, after entering the distributor 14 at an inlet mouth 16 opposite the outlet of the first portion 11, at the central axis 5, thus leaves the distributor 14 at an outlet mouth 17, opposite the inlet of the second portion 13 of the pipe 10, that is to say at a second inlet zone 19, located distant from the central axis 5, see [Fig. 7]. Figures 5 and 6 show that the second inlet zone 19 is slightly further from the central axis 5 than is the first inlet zone 12.

[0055] More precisely, as can be seen in Figures 4 and 7, the outlet of the passage 15 is generally perpendicular to the central axis 5. A cavity 25 is hollowed out in the cover 20, to receive therein the fluid leaving the passage 15, and return it to the second inlet zone 19. This cavity 25 therefore forms a fluid junction between the passage 15 within the distributor 14, and the second inlet zone 19, and the fluid circulates therein generally parallel to the central axis 5. Indeed, the outlet of the passage 15 being in a plane slightly further from the imprint 7 than is the pipe 10, the cavity 25 in the cover allows it to rise parallel to the central axis 5 into the pipe 10, at the level of the second inlet zone 19.

[0056] As mentioned above, the circulation of the fluid in the first portion 11 of the pipe 10 is done in a convergent manner in the direction of the central axis 5; in the second portion 13, the circulation of the fluid is done in a divergent manner moving away from the central axis 5 from the second inlet zone 19.

[0057] The second portion 13 then comprises parts in the shape of an arc of a circle and radial parts to connect them. The fluid then meanders, in a zone generally perpendicular to the central axis 5, moving away from the central axis 5, taking into account the profile of the pipe 10. The fluid thus circulates to its position furthest from the central axis 5, then joins a discharge channel 23 provided in the cover 20, which extends parallel to the central axis 5, to move the fluid away again from the zone where the cooling is organized, by a circulation along the central axis 5. It is thus understood that, in general, the cooling is organized in a zone which extends perpendicular to the central axis 5, that the fluid arrives there by following a path close to the central axis 5, then is slightly moved away from the central axis 5 to begin its cooling in the pipe 10 from a zone distant from the central axis 5 and by heading towards it, then, thanks to a circulation at the level of a parallel stage, further from the imprint 7, is sent again further from the central axis 5 as previously, but to then continue cooling from this distant zone but moving away from the central axis 5.There is therefore a first cooling at the level of a crown around the central axis 5, possibly a crown over a complete turn or a large part of a complete turn around the central axis 5, then a cooling of a part included inside this crown, then a part outside this crown.

[0058] Of course, several such sequences can be imagined: several convergent coolings and / or several divergent coolings.

[0059] The invention thus implements a method which can be described as follows.

[0060] The cooling of the molding device 1 is done by bringing the cooling liquid dissement, generally water or glycol, in a pipe 10 in the form of a coil, arranged, that is to say dug at a short distance from the imprint 7, against which the preform 3 will come previously heated. Cooling is therefore done by circulating the liquid close to the imprint 2, and, beforehand, the fluid is brought close to the imprint by circulating along the central axis 5, close to it. Thus, in the cooling sequence, the fluid begins to cool the base 4 at a distance slightly away from the central axis 5, circulates around the central axis 5 then approaches it until eventually reaching it.After this first cooling step, which is carried out using the first portion 11 of the pipe 10, the cooling fluid continues its cooling from a zone which is approximately as far from the central axis 5 as the zone at the start of cooling was, and in the direction of the periphery 9, therefore the external contour of the molding device 1. The pipe 10 allows cooling which is therefore organized on either side of a circle centered on the central axis 5. Initially, by circulating in the first portion 11 arranged inside this circle, the fluid cools the inside of this circle, starting with a part which forms at least a large part of the periphery of this circle, then continuing towards the central axis 5. Then the fluid, by circulating in the second portion 13, cools the outside of this circle, starting . close to said circle and gradually moving away from it towards the periphery. This circle, which therefore delimits the first cooling period, on the inside, and the second cooling period, on the outside, is located between the central axis 5 and the periphery 9. By first circulating along the circumference of the circle for at least half or even three-quarters of a turn before heading towards the central axis 5, the cooling therefore begins with a crown or ring at a distance from the central axis 5, before continuing inwards to the central axis 5. In the inner part of the circle, the fluid has no movement directed from the center towards the outside, which guarantees that the area of ​​the impression 7 at the periphery of this circle is indeed the area which undergoes the most significant cooling.

[0061] In particular, in the case where the imprint 7 has a petaloid shape, therefore with hollows generally of radial extension and distributed along the circumference, around a central part from which these hollows extend, the circle which delimits the first portion 11 on the inside and the second portion 13 on the outside is close to the transition zone between the central part and the hollows for the petaloid bottom. This circle, and therefore the first cooling ring defined by its circumference, is therefore such that the petaloid formation hollows are located largely outside the circle. A ring is therefore first cooled beyond which are the end of the hollows then forming the base of a petaloid bottom. The cooling of the petaloid part is done after the cooling of the central part, itself taking place after the cooling of an entire loop or almost.Cooling is therefore done on a ring, then in a convergent manner, then in a divergent manner from the same ring.

[0062] When blowing the preform 3, the top 24 is stretched at least in a direction perpendicular to the central axis 5, since both the diameter and the length of the preform 3 are significantly smaller than for the container 2. The base 8 of the container 2 then has an amorphous central zone, which is not stretched much, which is followed radially by an oriented peripheral zone, which has itself undergone a much greater stretching. Advantageously, the circle which delimits the first portion 11 on the inside and the second portion 13 on the outside is located at the transition between the amorphous central zone and the oriented peripheral zone of the base 8 of the container 2 then obtained. The impression 7 is therefore cooled first at the end of the amorphous central zone and the start of the oriented peripheral zone, rather than at the central axis 5 or the periphery 9.

[0063] Thus, advantageously, the first portion 11 can extend inside a circle whose radius is between one third and half the distance, relative to the central axis 5, of the lowest point of the impression 7, which therefore contributes to forming the seat of the container 2 at the level of its base 8. The arc of the first portion 11 is therefore pos possibly, relative to the central axis 5, at a distance which is between one third and half the distance, relative to the central axis 5, of the deepest points of the impression 7, these points subsequently forming the base of the container 2.

[0064] Figures 11 and 12 show spiral-type profiles. [Fig. 11] thus shows a bottom 6 of which the first portion 11 of the pipe 10 has a spiral shape. Said first portion 11 therefore begins at the level of the first inlet zone 12 which is distant from the central axis 5, as has already been explained, then gradually approaches the central axis 5. Here, the arc of the first portion 11 therefore also gradually approaches the central axis 5. In other words, in general, the arc of the first portion 11 can also make the fluid approach the central axis 5 while rotating around said central axis 5. As shown in this figure, the downstream end of the first portion 11, therefore the inlet mouth 16, is also at the level of the central axis 5.Generally, the first portion 11, from its upstream end, therefore the inlet zone 12, turns around and at a distance from the central axis 5 over at least a half-turn or even three-quarters of a turn or even more than one turn in the case of a spiral, before arriving at the level of said central axis 5 at its downstream end, therefore at the level of the inlet mouth 16.

[0065] [Fig. 12] shows a distributor 14 whose passage 15 has a spiral shape, traveled by the liquid in a divergent direction. By analogy, the fluid circulates convergently in the first portion 11 in the form of a spiral of [Fig.l 1].

[0066] [Fig. 12] shows the arrangement, with a spiral configuration, of the outlet mouth 17 at the periphery of the distributor 14, the inlet mouth 16 at the central axis 5, and the axial orifice 18 offset from the central axis. The spiral configuration of the passage 15 allows the fluid or coolant to flow continuously from the inlet mouth 16 to the outlet mouth 17, while avoiding flow disturbances that would otherwise be caused by right angles.

[0067] Preferably, the directions of flow of the fluid are reversed between, on the one hand, the essentially convergent flow which takes place in the first portion 11, and, on the other hand, the essentially divergent flow which takes place in the passage 15, and whether the profiles are curved and continuous as with spirals or rather discontinuous as with right angles. More precisely, the first portion 11 can cause the fluid to approach the central axis 5 by circulating around it in a clockwise direction, while the passage 15 can cause the fluid to move away from the central axis 5 by circulating around it in a clockwise direction. It is preferable that the directions be reversed between, on the one hand, the path close to footprint 7, in the first portion 11, and, on the other hand, the path on a floor further from footprint 7, where passage 15 is located, because this allows better distribution of the cooling effort.

[0068] Although the invention has been described with reference to preferred embodiments, it is conceivable to combine together all or part of their characteristics identified here.

Claims

Claims

1. Device (1) for molding a container (2) from a preform (3), said device (1) comprising a base (4) and having a central axis (5), said base (4) having a bottom (6), generally centered on the central axis (5) and in which is arranged an imprint (7) against which said preform (3) can be pressed so as to create the base (8) of said container (2), said bottom (6) having an external periphery (9) and comprising a pipe (10) which extends generally transversely to said central axis (5) between the latter and the periphery (9) to circulate therein a temperature control fluid of said device (1), Device characterized in that the pipe (10) has a first portion (11), which, on the one hand, has a first inlet zone (12) offset from the central axis (5) to receive the fluid and an arc distant from said central axis (5) which follows it, and which, on the other hand part, causes said fluid to flow while approaching said central axis (5),preferably after said arc.,

2. Device according to the preceding claim, characterized in that the pipe (10) has a second portion (13), located between the first portion (11) and the periphery (9), downstream of the first portion (11), so that the fluid flows first in the first portion (11), then in the second portion (13).

3. Device according to claim 2, characterized in that the base (4) comprises a distributor (14), arranged against the bottom (6) at the level of the central axis (5) and provided therein with a passage (15) for said fluid, said passage (15) having an inlet mouth (16) for receiving fluid which leaves the first portion (11), and an outlet mouth (17) for supplying the fluid to the second portion (13).

4. Device according to claim 3, characterized in that the distributor (14) has an axial orifice (18) extending at least partially along the central axis (5), and offset from the latter, said axial orifice (18) opening at the level of the first inlet zone (12) to bring the fluid into the first portion (11).

5. Device according to any one of claims 2 to 4, characterized in that the second portion (13), on the one hand, has a second inlet zone (19) at which it receives the fluid, and, on the other hand, causes it to flow away from the central axis (5) towards the periphery (9).

6. Device according to any one of claims 1 to 5, characterized in that the base (4) comprises a cover (20) in which a path (22) is arranged to bring the fluid towards the pipe (10) by moving it at least partially in the direction of the central axis (5) from an entry point (21), the pipe (10) taking for example the form of a groove dug in the base (4), which the cover (20) closes.

7. Device according to any one of claims 1 to 6, characterized in that the molding device (1) further comprises side shells which extend along the central axis (5), against which the preform (3) can be pressed so as to create the sides of the container (2) during blowing.

8. Method for manufacturing a plastic container (2) by blowing a preform (3), in which the preform (3) is placed in a molding device (1) having a central axis (5) and comprising a base (4) having a bottom (6), then a pressurized gas is injected into the preform (3) so that it follows the internal contour of said molding device (1) until a container (2) is formed, the method further comprising controlling the temperature of the molding device (1) using a fluid, a method characterized in that the temperature control is carried out by circulating a fluid in the molding device (1) at the base (4), and this along a path generally transverse to the central axis (5), starting, in a first phase, at a ring around the central axis (5), at a distance from the latter and from the external surface of the base (4),the fluid then moving towards or away from the central axis (5).,

9. Molding method according to claim 8, characterized in that the preform (3) has a top (24), and is placed in the molding device (1) so that its top (24), after stretch blow molding, is generally at the level of the central axis (5).

10. Method according to claim 8 or 9, characterized in that after the first phase of circulation of the fluid in the base (4), the fluid circulates approaching the central axis (5).

11. Method according to any one of claims 8 to 10, characterized in that the circulation of the fluid in the base (4) comprises a phase subsequent to the first phase, during which the fluid circulates away from the central axis (5) from beyond the crown.

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