FR3138879A1 - Concentric mold cooling - Google Patents

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 make circulating a temperature control fluid from 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

Concentric mold cooling

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 gas under pressure until it matches the shape of a hollow cavity provided within the mold. The subject of the invention is a device and a method for manufacturing containers by blowing.

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 part of their thermal calories to the blowing mold. Without evacuating these calories from the mold, the latter would continue to heat up with each blowing cycle until reaching a temperature which prevents production, in particular because of crippling production defects, such as deformation. It is then necessary to provide 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.

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

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 generally has a half-sphere shape. . This half-spherical part is therefore stretched to help form the bottom of the bottle, pressing against the impression presented by the bottom of the mold at this location. Prior to the blowing stage, the preform was manufactured by injection and, at the external end of this half-sphere, it generally shows the trace of the injection point.

Patent US7025584 discloses the implementation of a classic 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 more closely follows the surface of the valleys, thanks to hollow sections elongated in the axial direction, and judiciously partitioned arranged in the middle in these hollow longitudinal sections.

Publication CN202037856 illustrates a serpentine in the form of a divergent spiral. The cooling liquid enters the base of the mold from the peripheral surface of said base, and leaves the base also at this surface. The coolant enters the cooling pipe at the central part and gradually spreads to the periphery of the mold.

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

Considering the thickness and stretching of the central zone of the preform, as well as its importance in the mechanical resistance of the container subsequently obtained, the cooling in the mold of this zone is particularly important.

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.

Disclosure of the invention : The invention thus proposes a molding device as well as 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 ring around the central axis of the mold, continues in a convergent manner towards said center, then, after this cooling of the central part, continues with the part above. beyond said crown, preferably in a divergent manner, that is to say in the direction of the periphery of the mold.

In doing so, by avoiding heating of the cooling liquid which would be caused by an initial circulation near the cavity and towards the central axis, we ensure that the cooling is maximum, because obtained by the liquid at the start of its cycle under the imprint, at this crown area. 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 ring, then gradually approaches the central axis, then, in a second time, acts in the part between said crown and the periphery. The cooling power therefore decreases from a ring around the central axis, to the center, then from this ring to the periphery, following a pipe path of corresponding shape.

Thus, in accordance with the invention, it is proposed to organize, in the bottom of the mold, by appropriate pipework, 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 away from the center of the mold, where the top of the preform normally arrives, namely its injection point.

The subject of the invention is thus 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 an 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 for circulating a temperature control fluid therein of said device.

Pipeline 10 extends generally transversely to central axis 5 at a sufficiently short distance to have a significant thermal effect. In the case of a significantly non-flat container bottom, the pipe 10 can at least partially follow the profile of the imprint 7 and therefore have parts which 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 there 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.

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, 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 more important at the level of a crown around the central axis 5 than at the level of the central axis 5 itself. The first inlet zone 12 forms the arrival of the coolant 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 an entire turn, before the part of the pipe 10 which brings the fluid closer to the central axis 5. This arc , which can be an arc of a circle or of different profile, therefore ensures a first cooling at the level of a ring around the central axis 5, or at least part of such a ring 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 exerting a first cooling effect on a perimeter around and at a distance from the central axis 5, that the pipe 10 directs the fluid towards the central axis 5.

The first portion 11, where the start of the cooling action of the coolant occurs, 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 of the central axis 5.

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 into 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 fluid flow. 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.

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

According to another possible additional characteristic, the base 4 comprises a distributor 14, arranged against the bottom 6 at the level of the central axis 5 and provided within it with a passage 15 for said fluid, said passage 15 having a mouth of inlet 16 to receive fluid which leaves the first portion 11, and an outlet mouth 17 to supply the fluid to the second portion 13, in particular at the level of the second inlet zone 19 of the second portion 13 which allows bring the cooling fluid from the downstream end of the first portion 11 to the upstream end of the second portion 13, further away 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 the second portion, in the form of a groove, create walls between them at the level of the bottom 6. The cover comes into contact with a part of these walls, another part of these walls comes into contact with the distributor at one of these faces, its other face being taken into the cover.

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 be done in a plane further from the footprint than is that where the first portion 11 of pipeline 10 is located.

The inlet mouth 16 is therefore located in particular at the level of 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 particularly offset with respect to the central axis 5 and away from it, facing the second zone inlet 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.

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

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 a cooled interior part after the exterior part.

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 towards 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.

According to another possible additional characteristic, the base 4 comprises a cover 20 in which a path 22 is provided 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 closes the cover 20. The path 22 opens for example at the level of the axial orifice 18 of the distributor 14. If necessary, as show Figures 2 and 8, the cover 20 also comprises an evacuation channel 23 which is in communication, on the one hand, with the outlet of the pipe 10 to receive the fluid, and, on the other hand, with the outside of the base 4 to send the liquid out of the molding device. The cover 20 generally has the shape of a cylinder of revolution.

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 allows the final packaging to be formed. The arrangement 1 thus includes not only the base 4 which will define the base of the container 2, but also at least one and preferably two side shells, which come opposite each other during blowing, to define the sides of the container 2.

The invention also relates to a method which implements the device described above. The subject of the invention is thus a method of 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 gas under pressure is injected into the preform 3 so that it matches the interior contour of said molding device 1 until forming a container 2, the method comprising, in addition, controlling the temperature of the molding device 1 at the same time. using a fluid.

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

This crown delimits a part which is interior to it, comprising the central axis 5 and a part which is exterior to it, with the periphery 9. The cooling begins at the level of this crown, then continues in the interior part approaching the 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 exterior part, after communication between the two parts which takes place in an offset plane, preferably further away from the imprint 9 than are the first portion 11 of the pipe 10 which extends for the interior part and the second portion 13 of the pipe 10 which extends for the exterior part.

According to a possible characteristic of the process, the preform 3 has a vertex 24, and is placed in the molding device 1 so that its vertex 24, after stretching 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 beginning 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 crown portion which surrounds the top 24. Unlike usual cooling techniques, the cooling fluid is therefore not heated as it approaches the cavity 7 by advancing along the central axis 5 up to the pipe 10 , the cooling does not begin either with the tip or summit 24 of the preform, therefore the center of the container 2 to gradually move away from it, nor with the periphery 9 to approach the central axis 5, but begins with a crown central, 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.

According to a possible characteristic of the process after the first phase of circulation of the fluid in the base 4, the fluid circulates approaching the central axis 5. Thus, after the first phase during which the fluid acts on a crown 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 crown , then towards the center, therefore the central axis 5. This circumferential then convergent circulation in the first portion 11 is close to the imprint 7, that is to say in particular closer to the imprint than communication between the first and second portions.

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 to the periphery 9 of the base 4. The fluid then circulates in the second portion 13 of the pipe, from the second entry 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 traveled in a divergent direction, or simply successive arcs of a circle, joined by radial sections.

Brief description of the drawings : Other advantages and characteristics will become clearer from the following description of a single alternative embodiment, given as a non-limiting example, of the device according to the invention, with reference to the attached drawings. on which ones :
shows a sectional view of the molding device, with the stacking of the cover, the distributor and the base
illustrates the cover and the distributor housed therein
represents a section which shows the cover and the distributor
shows, in section, the stacking of the bottom, the distributor and the cover, in a plane offset from the main axis
shows the pipe as dug in the bottom of the base, with two disjointed portions
shows the pipe as dug, with the distributor in its operating position
shows the distributor within the cover, with in particular the groove which allows the fluid to pass from the distributor to the second portion of the pipe
shows a section on a plane perpendicular to the main axis, at the level of the ribs which delimit the pipe, with the distributor taken between them and the cover
shows a preform
shows a container
shows a spiral profile
shows a spiral profile for the distributor

Mode of carrying out the invention :

The molding device 1 according to the invention serves to receive preforms 3 into which a pressurized fluid is injected so as to press them against the impression 7 presented by said molding device 1. This molding device 1 comprises at least a base 4, which serves to form the normally lower part of the future container 2, in other words its bottom, thanks to which the container 2 then rests vertically on a horizontal surface.

The molding device 1 can also include lateral shells, which will form the side surfaces of the container 2. The molding device 1 is therefore at least a mold base but can include other elements which make it a mold of complete blowing.

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; in addition, 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 has been mentioned, which obviously depends on the other components that it may possibly include.

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

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 imprint surface 7 to create the shape of the container 2. On the side opposite the imprint 7, the bottom 6 has a pipe 10, for example in the form of at least one groove. There shows this part of the bottom 6 with a pipe 10 made of two grooves, each in one piece. It is of course possible to imagine more than two distinct gorges. 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 of their own, and, on the other hand, of straight portions, perpendicular to the central axis 5 and allowing the arc of a first ray to be joined to the arc of a second ray. We could also envisage a pipe 10 with at least one spiral, namely a profile whose distance relative to the central axis 5 changes over a circumference less or even greater than a complete turn.

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 shaping.

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 The central axis 5 can generally follow the shape of the cavity 7, to maximize heat exchange.

The pipe 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 to contribute to thus closing the pipe 10 hermetically.

The cover 20 allows, 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 presents. It also possibly allows the fluid to be evacuated 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 towards 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 is close to the center, namely the central axis 5, possibly only slightly offset from it as described below, 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.

There shows the path 22 within the cover 20, with a part aligned with the central axis 5. This embodiment also illustrates the possibility of a separation of the path 22 perpendicular to the central axis 5, then a following section parallel again to the central axis 5, offset relative to this axis. In practice, this recess is obtained by drilling from one edge of the device, therefore from the periphery 9, until reaching the part of the path 22 which is aligned with the central axis 5 and passing it to form said recess. We understand that the part of the drilling on the other side of the central axis 5 with respect to the recess is not used for the circulation of fluid towards the bottom 6, but forms a dead end in the path of the fluid, and therefore does not part of the path 22. Generally speaking, the parts of the holes used to create said path 22 but in which the fluid cannot circulate are not part of the path 22 because they form an impasse.

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 it 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.

The distributor 14 generally has the shape of a disc or pellet, and is positioned at the 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 pipe 10 together.

More precisely, as shown in in particular, in a 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 in the direction of 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 cavity 7 thanks to a flow essentially parallel to the central axis 5. This axial orifice 18 allows the cooling liquid to cross 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 the periphery 9.

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 far from the central axis 5, see . This passage 15 makes it possible to put two successive portions of pipe 10 in 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, simply being located opposite, and the outlet mouth 17 communicates with the upstream end of a second portion 13 of pipe 10, again simply facing each other.

The circulation of the fluid is therefore done as follows.

The fluid is initially received by the cover 20 at the level of the central axis 5, more precisely at the level of a passage hole presented by the path 22 which is dug there, see . 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 disk. Indeed, this path 22 emerges from the cover 20 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 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 a zone close to the central axis 5 therefore advances along the central axis 5 by first crossing the path 22 dug in said cover 20 then the axial orifice 18, all closer but not confused with the axis central 5 than periphery 9.

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 ring which it presents around the central axis 5.

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 axis central 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 . Once brought by the cover 20 then the distributor 14, the fluid therefore arrives in the cooling pipe 10 slightly distant from the central axis 5. The fluid therefore then circulates perpendicular to the central axis 5 in the first portion 11 , which starts away from the central axis 5 and ends closer to the central axis 5 preferably at the level of the central axis 5. As shown in the , 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 circular arc can be followed by a radial linear part to bring the fluid to the central axis 5. We can of course envisage a more sophisticated shape for the first portion 11, such as for example a spiral shape, or several more 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 there from a zone 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 the , in which case the first portion 11 extends over all or part of a disc centered on the central axis 5; we can also envisage that the end of the first portion 11 is also distant from the central axis 5, however closer to it than is the first entry zone 12, in which case the first portion 11 extends over all or part of a crown 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 .

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 of the imprint 7 through a hole along the central axis 5, then continues in a divergent part, visible at the . 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 makes it possible to move the fluid away from the central axis 5 and which is located more away 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 one is closer to the imprint 7 than the divergent one.

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

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 dug in the cover 20, to then receive the fluid leaving the passage 15. , and return it to the second entry zone 19. This cavity 25 therefore forms a fluid junction between the passage 15 within the distributor 14, and the second entry zone 19, and the fluid circulates there generally parallel to the central axis 5. In fact, the outlet of the passage 15 being in a plane slightly further from the cavity 7 than is the pipe 10, the cavity 25 in the cover allows it to be raised parallel to the central axis 5 as far as pipeline 10, at the level of the second entry zone 19.

As mentioned above, the circulation of the fluid in the first portion 11 of the pipe 10 takes place in a convergent manner in the direction of the central axis 5; in the second portion 13, the circulation of the fluid takes place in a divergent manner moving away from the central axis 5 from the second entry zone 19.

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 an evacuation channel 23 provided in the cover 20, which extends parallel to the central axis 5, to again move the fluid away from the zone where the cooling is organized, by circulation the along the central axis 5. We thus understand 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 axis central 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 moving towards it, then, thanks to circulation at the level of a floor parallel, further from the footprint 7, is returned 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. It occurs therefore a first cooling at the level of a crown around the central axis 5, possibly a crown over a complete revolution or a large part of a complete revolution around the central axis 5, then a cooling of a part included inside this crown, then part outside this crown.

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

The invention thus implements a process which can be described as follows.

The cooling of the molding device 1 is done by bringing the cooling liquid, generally water or glycol, into a pipe 10 in the form of a serpentine, arranged, that is to say dug a short distance from the the imprint 7, against which the previously heated preform 3 will come. Cooling is therefore done by circulating the liquid close to the cavity 2, and, beforehand, the fluid is brought close to the cavity 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 distant 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 done thanks to the first portion 11 of the pipe 10, the cooling fluid continues its cooling from a zone which is approximately as distant from the central axis 5 as was the zone of the start of cooling, 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 interior 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, then circulating in the second portion 13, cools the exterior of this circle, starting near said circle and gradually moving away from it towards the periphery . This circle, which therefore delimits the first cooling period, inside, and the second cooling period, 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 moving towards the central axis 5, the cooling therefore begins with a crown or ring at a distance from the central axis 5, before continuing towards the 'interior up to the central axis 5. In the interior part of the circle, the fluid has no movement directed from the center to the exterior, which guarantees that the area of the indentation 7 at the level of the periphery of this circle is indeed the zone which undergoes the most significant cooling.

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 located close to the transition zone between the central part and the hollows for the petaloid bottom. This circle, and therefore the crown of first cooling defined by its circumference, is therefore such that the petaloid formation hollows are largely outside the circle. We therefore first cool a crown beyond which are the ends of the hollows then forming the base of a petaloid base. The cooling of the petaloid part takes place after the cooling of the central part, itself taking place after the cooling of an entire or almost entire loop. The cooling therefore takes place on a ring, then in a convergent manner, then in a divergent manner from the same ring.

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, little stretched, which is followed radially by an oriented peripheral zone, which has itself undergone 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 level of the transition between the amorphous central zone and the oriented peripheral zone of the base 8 of the container 2 then got. We therefore cool the cavity 7 first at the end of the amorphous central zone and the beginning of the oriented peripheral zone, rather than at the central axis 5 or the periphery 9.

Thus, advantageously, the first portion 11 can extend inside a circle whose radius is between a third and half of the distance, relative to the central axis 5, of the lowest point of the imprint 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 possibly located, relative to the central axis 5, at a distance which is between a third and a half of the distance, relative to the central axis 5, of the deepest points of the imprint 7, these points subsequently forming the base of the container 2.

Figures 11 and 12 show spiral type profiles. There 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 entry 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 cause the fluid to 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 here also at the level of the central axis 5. Generally speaking, the first portion 11, from its upstream end, therefore the entry zone 12, rotates around and at a distance from the central axis 5 over at least half a 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.

There shows a distributor 14 whose passage 15 has a spiral shape, through which the liquid passes in a divergent direction. By analogy, the fluid circulates convergently in the first spiral-shaped portion 11 of the .

There shows the arrangement, with a spiral configuration, of the outlet mouth 17 at the periphery of the distributor 14, of the inlet mouth 16 at the level of the central axis 5, and of the offset axial orifice 18 relative to 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 which would otherwise be caused by right angles.

Preferably, the directions of flow of the fluid are inverse 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 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. central axis 5 by circulating around it clockwise. It is preferable that the directions are reversed between, on the one hand, the path close to the footprint 7, in the first portion 11, and, on the other hand, the path on a floor further away from the footprint 7, where passage 15 is located, because this allows better distribution of the cooling effort.

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

Claims (11)

Device for molding (1) a container (2) from 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 remote from said central axis (5) which follows it, and which, on the other hand, causes said fluid to flow approaching said central axis (5), preferably after said arc. 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 into the first portion (11), then in the second portion (13). 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 within it with a passage (15) for said fluid, said passage (15) having an inlet mouth (16) for receiving fluid exiting the first portion (11), and an outlet mouth (17) for supplying fluid to the second portion (13). 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 zone of inlet (12) to bring the fluid into the first portion (11). 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, makes it flow away from the central axis (5) towards the periphery (9). 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 provided for bringing the fluid towards the pipe (10) by moving it at least partially in the direction of the central axis (5) from a point inlet (21), the pipe (10) taking for example the shape of a groove dug in the base (4), which is closed by the cover (20). 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 ) when blowing. Method of 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 forming a container (2), the method comprising, in addition, controlling the temperature of the molding device (1) using a fluid, method characterized in that,
temperature control is achieved by circulating a fluid in the molding device (1) at the level of 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 ring around the central axis (5), at a distance from the latter as well as from the exterior surface of the base (4), the fluid for example then moving towards or moving away from the central axis (5). Molding process 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 stretching blow molding, is generally at the level of the central axis (5). 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). 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.